Publications

@article{nokey,

title = {Synthesis, Structural Analysis, and Degradation Behaviour of Potassium Tin Chloride as Chloride-Ion Batteries Conversion Electrode Material},

author = {Soutam Panja; Yidong Miao; Johannes Döhn; Jaehoon Choi; Simon Fleischmann; Shivaraju Guddehalli Chandrappa; Thomas Diemant; Axel Groß; Guruprakash Karkera; Maximilian Fichtner},

doi = {10.1002/adfm.202413489},

year  = {2024},

date = {2024-09-09},

journal = {Advanced Functional Materials},

pages = {2413489},

abstract = {Chloride–ion batteries (CIBs) offer a compelling alternative to conventional battery systems, particularly in applications demanding cost-effectiveness and resource sustainability. However, the development of tailored electrode materials remains a critical bottleneck for CIB advancement. In this study, an untapped class of perovskite-based material, potassium hexachlorostannate (K2SnCl6, denoted as KSC) is synthesized via a facile mechanochemical route for the first time. The prepared KSC is subjected to various characterization techniques to confirm its crystal structure and morphology. Herein, KSC exhibits intriguing electrochemical performance in a non-aqueous CIB configuration, utilizing a lithium metal counter electrode. Furthermore, ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis, reveal a conversion reaction mechanism involving chloride ion shuttling and provide insights into structural evolution during cycling. Moreover, the density functional theory (DFT) studies support additional degradation products that can potentially limit the performance of these materials as potential battery electrodes in CIBs.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {High-Rate Polymeric Redox in MXene-Based Superlattice-Like Heterostructure for Ammonium Ion Storage},

author = {Chaofan Chen; Glenn Quek; Hongjun Liu; Lars Bannenberg; Ruipeng Li; Jaehoon Choi; Dingding Ren; Ricardo Javier Vázquez; Bart Boshuizen; Bjørn‐Ove Fimland; Simon Fleischmann; Marnix Wagemaker; De‐en Jiang; Guillermo Carlos Bazan; Xuehang Wang},

doi = {10.1002/aenm.202402715},

year  = {2024},

date = {2024-09-03},

urldate = {2024-09-03},

journal = {Advanced Energy Materials},

pages = {2402715},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Controlling structure and morphology of MoS2 via sulfur precursor for optimized pseudocapacitive lithium intercalation hosts},

author = {Maciej Tobis and Mennatalla Elmanzalawy and Jaehoon Choi and Elżbieta Frąckowiak and Simon Fleischmann},

doi = {10.1002/batt.202400277},

year  = {2024},

date = {2024-07-02},

urldate = {2024-04-24},

journal = {Batteries & Supercaps},

pages = {e202400277},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Unifying electrolyte formulation and electrode nanoconfinement design to enable new ion–solvent cointercalation chemistries},

author = {Haocheng Guo and Mennatalla Elmanzalawy and Prashanth Sivakumar and Simon Fleischmann},

doi = {10.1039/D3EE04350A },

year  = {2024},

date = {2024-02-13},

urldate = {2024-02-13},

journal = {Energy & Environmental Science},

volume = {17},

pages = {2100-2116},

abstract = {Electrochemical ion intercalation is a multi-step process typically involving transport of solvated ions through the liquid electrolyte phase, desolvation of ions at the electrochemical liquid/solid interface, and solid-state diffusion of bare ions within the host electrode. Instead of stripping solvent molecules at the interface during the desolvation step, ions can also intercalate together with a (partially) intact solvation sheath into the host electrode, giving rise to cointercalation chemistries. The thermodynamics and kinetics of ion–solvent cointercalation processes are fundamentally different from the more common case of bare ion intercalation. They offer the possibilities of improved kinetics, modified redox potentials, and enabling intercalation chemistries that are thermodynamically inhibited for bare ions. Thus achieving, identifying, and controlling electrochemical ion–solvent cointercalation are of importance to the field of electrochemical energy storage, particularly, in order to enable post-lithium cell chemistries. Herein, we analyze current efforts of electrolyte formulation and electrode nanoconfinement design to control (achieve or inhibit) cointercalation. Analytical tools to unambiguously identify cointercalation phenomena are discussed. While most current efforts singularly focus on the electrolyte formulation, we propose a unified approach of matching electrolytes with the host's nanoconfinement environment to broaden the range and increase the effectiveness of ion–solvent cointercalation chemistries for use in multivalent ion intercalation, low-temperature batteries, supercapacitors, or dual-ion batteries.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Simultaneous control of crystallite size and interlayer spacing of MoS2 to achieve pseudocapacitive lithium intercalation},

author = {Jaehoon Choi and Hyein Moon and Simon Fleischmann},

doi = {10.1016/j.electacta.2024.143774},

year  = {2024},

date = {2024-01-04},

urldate = {2024-01-04},

journal = {Electrochimica Acta},

volume = {476},

pages = {143774},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Quantifying defects in carbon nanotubes undergoing prolonged electrochemical cycling with Raman phase map},

author = {Sirshendu Dinda and Tobias Braun and Frank D Pammer and Jaehoon Choi and Simon Fleischmann and Maximilian Fichtner},

doi = {10.1016/j.carbon.2023.118753},

year  = {2023},

date = {2023-12-22},

journal = {Carbon},

volume = {218},

pages = {118753},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Hydronium Intercalation Enables High Rate in Hexagonal Molybdate Single Crystals},

author = {Haocheng Guo and Sicheng Wu and Wen Chen and Zhen Su and Qing Wang and Neeraj Sharma and Chengli Rong and Simon Fleischmann and Zhaoping Liu and Chuan Zhao},

doi = {10.1002/adma.202307118},

year  = {2023},

date = {2023-11-28},

urldate = {2023-11-28},

journal = {Advanced Materials},

volume = {36},

pages = {2307118},

abstract = {Rapid proton transport in solid-hosts promotes a new chemistry in achieving high-rate Faradaic electrodes. Exploring the possibility of hydronium intercalation is essential for advancing proton-based charge storage. Nevertheless, this is yet to be revealed. Herein, a new host is reported of hexagonal molybdates, (A2O)x·MoO3·(H2O)y (A = Na+, NH4+), and hydronium (de)intercalation is demonstrated with experiments. Hexagonal molybdates show a battery-type initial reduction followed by intercalation pseudocapacitance. Fast rate of 200 C (40 A g−1) and long lifespan of 30 000 cycles are achieved in electrodes of monocrystals even over 200 µm. Solid-state nuclear magnetic resonance confirms hydronium intercalations, and operando measurements using electrochemical quartz crystal microbalance and synchrotron X-ray diffraction disclose distinct intercalation behaviours in different electrolyte concentrations. Remarkably, characterizations of the cycled electrodes show nearly identical structures and suggest equilibrium products are minimally influenced by the extent of proton solvation. These results offer new insights into proton electrochemistry and will advance correlated high-power batteries and beyond.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Elmanzalawy2023,

title = {Mechanistic understanding of microstructure formation during synthesis of metal oxide/carbon nanocomposites},

author = {Mennatalla Elmanzalawy and Alessandro Innocenti and Maider Zarrabeitia and Nicolas J. Peter and Stefano Passerini and Veronica Augustyn and Simon Fleischmann},

doi = {10.1039/D3TA01230A},

year  = {2023},

date = {2023-06-12},

urldate = {2023-06-12},

journal = {Journal of Materials Chemistry A},

abstract = {Nanocomposite materials consisting of metal oxide and carbon are of interest as electrode materials for both high rate intercalation-type and high capacity conversion-type charge storage processes. Facile synthesis processes like the pyrolysis of an organic carbon-source can yield a well-dispersed carbon phase within the metal oxide structure. Detailed understanding of the carbon formation process is required to tailor the resulting material microstructure. Herein, both the formation and the final microstructure of a molybdenum oxide/carbon nanocomposite are studied in detail. Octylamine assembled in the interlayer space of layered MoO3 serves as a carbon source. The structural changes during pyrolysis are characterized using a combination of in situ heating X-ray diffraction with simultaneous FTIR- and mass spectroscopy-coupled thermogravimetric analysis experiments. These reveal mobility and partial desorption of octylamine and interlayer water at low temperatures, octylamine decomposition and loss of long-range order at intermediate temperatures, and carbothermic reduction of molybdenum oxide at high temperatures during pyrolysis. The resulting nanocomposite mainly contains nanocrystalline MoO2 domains surrounded by a well-dispersed carbon phase, as observed with scanning transmission electron microscopy of focus-ion beam prepared cross-sectional lamellae. The electrochemical behavior is evaluated in organic, lithium-containing electrolyte for both intercalation and conversion-type reactions, showing good intercalation kinetics and a high first cycle efficiency for the conversion-type reaction.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Shin2022,

title = {Cryogenic electron microscopy workflows for the characterization of electrochemical interfaces and interphases in batteries},

author = {Yuyoung Shin and Dominik Stepien and Marco Hepp and Benjamin Butz and Dominic Bresser and Simon Fleischmann},

doi = {10.1016/j.jpowsour.2022.232515},

year  = {2023},

date = {2023-02-01},

urldate = {2023-02-01},

journal = {Journal of Power Sources},

volume = {556},

pages = {232515},

abstract = {Fundamental understanding of (electro-)chemical processes occurring in batteries down to an atomic level is essential to further improve the performance of commercialized battery technologies and to establish novel cell chemistries. Transmission electron microscopy techniques are well-suited for highly localized structural and chemical analysis, but many electrode materials and their corresponding electrode/electrolyte interfaces and interphases are sensitive towards ambient conditions and/or the high energy electron beam. This necessitates cryogenic cooling of the specimen during sample preparation, transfer, and/or imaging. Here, we highlight the major experimental workflows derived from sample-specific requirements, which vary in complexity and infrastructural requirements. The purpose of this Perspective is to give a comprehensive guideline on both the opportunities and requirements of cryogenic (transmission) electron microscopy to analyze materials/phenomenon-specific questions relevant to battery research.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann(*)2022,

title = {Continuous transition from double-layer to Faradaic charge storage in confined electrolytes},

author = {Simon Fleischmann and Yuan Zhang and Xuepeng Wang and Peter T Cummings and Jianzhong Wu and Patrice Simon and Yury Gogotsi and Volker Presser and Veronica Augustyn},

doi = {10.1038/s41560-022-00993-z},

year  = {2022},

date = {2022-03-17},

urldate = {2022-03-17},

journal = {Nature Energy},

volume = {7},

pages = { 222-228},

abstract = {The capacitance of the electrochemical interface has traditionally been separated into two distinct types: non-Faradaic electric double-layer capacitance, which involves charge induction, and Faradaic pseudocapacitance, which involves charge transfer. However, the electrochemical interface in most energy technologies is not planar but involves porous and layered materials that offer varying degrees of electrolyte confinement. We suggest that understanding electrosorption under confinement in porous and layered materials requires a more nuanced view of the capacitive mechanism than that at a planar interface. In particular, we consider the crucial role of the electrolyte confinement in these systems to reconcile different viewpoints on electrochemical capacitance. We propose that there is a continuum between double-layer capacitance and Faradaic intercalation that is dependent on the specific confinement microenvironment. We also discuss open questions regarding electrochemical capacitance in porous and layered materials and how these lead to opportunities for future energy technologies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann(*)2021,

title = {Electrochemically-induced Deformation Determines the Rate of Lithium Intercalation in Bulk-TiS2},

author = {Simon Fleischmann and Hui Shao and Pierre-Louis Taberna and Patrick Rozier and Patrice Simon},

doi = {10.1021/acsenergylett.1c01934},

year  = {2021},

date = {2021-11-01},

urldate = {2021-11-01},

journal = {ACS Energy Lett.},

volume = {6},

pages = {4173–4178},

abstract = {Understanding the kinetic limitations of intercalation reactions is essential to create high-power intercalation host materials. In this Letter, we show the existence of both diffusion-limited and non-diffusion-limited lithiation regimes in the model material bulk TiS2. The regions can be clearly identified by electrochemical impedance spectroscopy. A decreasing charge-transfer resistance is observed with increasing electrode polarization in the diffusion-limited region, whereas it remains constant when the electrochemical process is non-diffusion-limited. We highlight how TiS2 interlayer deformation is closely tied to the intercalation kinetics. While regions of TiS2 interlayer expansion/contraction are correlated with diffusion limitations, lithiation occurring under constant interlayer spacing is non-diffusion-limited: the material exhibits pseudocapacitive behavior. Larger TiS2 interlayer spacing results in faster ionic transport. The study sheds light on the close ties between deformation, interlayer distance, and intercalation kinetics in a model layered host material.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Liang2021,

title = {Engineering the Interlayer Spacing by Pre‐Intercalation for High Performance Supercapacitor MXene Electrodes in Room Temperature Ionic Liquid},

author = {Kun Liang and Ray A Matsumoto and Wei Zhao and Naresh C Osti and Ivan Popov and Bishnu P Thapaliya and Simon Fleischmann and Sudhajit Misra and Kaitlyn Prenger and Madhusudan Tyagi and Eugene Mamontov and Veronica Augustyn and Raymond R Unocic and Alexei P Sokolov and Sheng Dai and Peter T Cummings and Michael Naguib},

doi = {10.1002/adfm.202104007},

year  = {2021},

date = {2021-08-16},

journal = {Adv. Funct. Mater.},

volume = {31},

issue = {33},

pages = {2104007},

abstract = {MXenes exhibit excellent capacitance at high scan rates in sulfuric acid aqueous electrolytes, but the narrow potential window of aqueous electrolytes limits the energy density. Organic electrolytes and room-temperature ionic liquids (RTILs) can provide higher potential windows, leading to higher energy density. The large cation size of RTIL hinders its intercalation in-between the layers of MXene limiting the specific capacitance in comparison to aqueous electrolytes. In this work, different chain lengths alkylammonium (AA) cations are intercalated into Ti3C2Tx, producing variation of MXene interlayer spacings (d-spacing). AA-cation-intercalated Ti3C2Tx (AA-Ti3C2), exhibits higher specific capacitances, and cycling stabilities than pristine Ti3C2Tx in 1 m 1-ethly-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMIMTFSI) in acetonitrile and neat EMIMTFSI RTIL electrolytes. Pre-intercalated MXene with an interlayer spacing of ≈2.2 nm, can deliver a large specific capacitance of 257 F g−1 (1428 mF cm−2 and 492 F cm−3) in neat EMIMTFSI electrolyte leading to high energy density. Quasi elastic neutron scattering and electrochemical impedance spectroscopy are used to study the dynamics of confined RTIL in pre-intercalated MXene. Molecular dynamics simulations suggest significant differences in the structures of RTIL ions and AA cations inside the Ti3C2Tx interlayer, providing insights into the differences in the observed electrochemical behavior.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Wang2021,

title = {Fast Proton Insertion in Layered H2W2O7 via Selective Etching of an Aurivillius Phase},

author = {Ruocun Wang and Yangyunli Sun and Alexander Brady and Simon Fleischmann and Tim B. Eldred and Wenpei Gao and Hsiu-Wen Wang and De-en Jiang and Veronica Augustyn},

doi = {10.1002/aenm.202003335},

year  = {2021},

date = {2021-01-02},

journal = {Advanced Engineering Materials},

volume = {11},

pages = {2003335},

abstract = {H2W2O7, a metastable material synthesized via selective etching of the Aurivillius-related Bi2W2O9, is demonstrated as an electrode for high power proton-based energy storage. Comprehensive structural characterization is performed to obtain a high-fidelity crystal structure of H2W2O7 using an iterative approach that combines X-ray diffraction, neutron pair distribution function, scanning transmission electron microscopy, Raman spectroscopy, and density functional theory modeling. Electrochemical characterization shows a capacity retention of ≈80% at 1000 mV s–1 (1.5-s charge/discharge time) as compared to 1 mV s–1 (≈16-min charge/discharge time) with cyclability for over 100 000 cycles. Energetics from density functional theory calculations indicate that proton storage occurs at the terminal oxygen sites within the hydrated interlayer. Last, optical micrographs collected during in situ Raman spectroscopy show reversible, multicolor electrochromism, with color changes from pale yellow to blue, purple, and last, orange as a function of proton content. These results highlight the use of selective etching of layered perovskites for the synthesis of metastable transition metal oxide materials and the use of H2W2O7 as an anode material for proton-based energy storage or electrochromic applications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Frank2020,

title = {Structural and chemical characterization of MoO2/MoS2 triple-hybrid materials using electron microscopy in up to three dimensions},

author = {Anna Frank and Thomas Gänsler and Stefan Hieke and Simon Fleischmann and Samantha Husmann and Volker Presser and Christina Scheu},

doi = {10.1039/D0NA00806K},

year  = {2020},

date = {2020-12-29},

journal = {Nanoscale Advances},

volume = {3},

issue = {4},

pages = {1067-1076},

abstract = {This work presents the synthesis of MoO2/MoS2 core/shell nanoparticles within a carbon nanotube network and their detailed electron microscopy investigation in up to three dimensions. The triple-hybrid core/shell material was prepared by atomic layer deposition of molybdenum oxide onto carbon nanotube networks, followed by annealing in a sulfur-containing gas atmosphere. High-resolution transmission electron microscopy together with electron diffraction, supported by chemical analysis via energy dispersive X-ray and electron energy loss spectroscopy, gave proof of a MoO2 core covered by few layers of a MoS2 shell within an entangled network of carbon nanotubes. To gain further insights into this complex material, the analysis was completed with 3D electron tomography. By using Z-contrast imaging, distinct reconstruction of core and shell material was possible, enabling the analysis of the 3D structure of the material. These investigations showed imperfections in the nanoparticles which can impact material performance, i.e. for faradaic charge storage or electrocatalysis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2020c,

title = {Pseudocapacitance: From Fundamental Understanding to High Power Energy Storage Materials},

author = {Simon Fleischmann and James B Mitchell and Ruocun Wang and Cheng Zhan and De-en Jiang and Volker Presser and Veronica Augustyn},

doi = {10.1021/acs.chemrev.0c00170},

year  = {2020},

date = {2020-06-28},

journal = {Chem. Rev.},

volume = {120},

pages = {6738–6782},

abstract = {There is an urgent global need for electrochemical energy storage that includes materials that can provide simultaneous high power and high energy density. One strategy to achieve this goal is with pseudocapacitive materials that take advantage of reversible surface or near-surface Faradaic reactions to store charge. This allows them to surpass the capacity limitations of electrical double-layer capacitors and the mass transfer limitations of batteries. The past decade has seen tremendous growth in the understanding of pseudocapacitance as well as materials that exhibit this phenomenon. The purpose of this Review is to examine the fundamental development of the concept of pseudocapacitance and how it came to prominence in electrochemical energy storage as well as to describe new classes of materials whose electrochemical energy storage behavior can be described as pseudocapacitive.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2020b,

title = {Electrochemical Reactivity under Confinement Enabled by Molecularly Pillared 2D and Layered Materials},

author = {Simon Fleischmann and Michael A Spencer and Veronica Augustyn},

doi = {10.1021/acs.chemmater.0c00648},

year  = {2020},

date = {2020-03-31},

journal = {Chemistry of Materials},

volume = {32},

pages = {3325–3334},

abstract = {This perspective presents an overview of how confinement can be used to tune electrochemical reactivity and the concept of using molecularly pillared 2D and layered materials to experimentally study this phenomenon. Many theoretical and computational studies have shown that the confinement of liquid-phase reactants to nano- or subnanometer spaces influences their electrochemical reactivity. While confinement is ubiquitous in various high surface area materials used as electrodes, experimental studies of this effect are scarce due to the challenge of deconvoluting the many competing influences on the measured electrochemical signal. This creates an exciting opportunity for the synthesis of well-defined materials platforms capable of confining liquid electrolytes and reactants for understanding electrochemical reactivity under confinement. In particular, a precise confinement geometry can be achieved with the use of 2D and layered materials whose interlayers have been tuned with the use of molecular pillars.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2020,

title = {Interlayer Separation in Hydrogen Titanates Enables Electrochemical Proton Intercalation},

author = {Simon Fleischmann and Yangyunli Sun and Naresh C Osti and Ruocun Wang and Eugene Mamontov and De-en Jiang and Veronica Augustyn},

doi = {10.1039/C9TA11098D},

year  = {2020},

date = {2020-01-01},

journal = {Journal of Materials Chemistry A},

volume = {8},

pages = {412-421},

abstract = {Electrochemical proton intercalation into titanium oxides is typically limited to the near-surface region, necessitating the use of nanostructured high surface area materials to obtain high capacities. Here, we investigate the role of materials structure to extend intercalation beyond the near-surface region. Employing a series of hydrogen titanates (HTOs), we find that electrochemical protonation capacity significantly increases with interlayer structural protonation. The maximum capacity of ∼80 mA h g−1 is achieved with H2Ti3O7, which also undergoes reversible structural and optical changes during the de/intercalation process. Using quasi-elastic neutron scattering, we show that structural protons are highly confined in the HTO interlayer with only localized, but not translational, dynamics. Electrochemical protonation leads to a contraction of the H2Ti3O7 interlayer without causing significant strain in the two-dimensional titanate layers. Density functional theory calculations indicate more favorable adsorption energy for intercalated protons in H2Ti3O7 as compared to HTOs with fewer structural protons. We hypothesize that interlayer structural protons are the structural feature responsible for the high electrochemical protonation capacity in H2Ti3O7 because they effectively decrease the interconnections between the titanate layers. This enables facile compensation of the electrochemically introduced strain via one-dimensional interlayer contraction. These results demonstrate the special structural requirements for bulk proton intercalation in titanium oxides, and offer a new materials design strategy for high energy density aqueous energy storage.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Mitchell2019,

title = {Confined Interlayer Water Promotes Structural Stability for High-Rate Electrochemical Proton Intercalation in Tungsten Oxide Hydrates},

author = {James B Mitchell and Natalie R Geise and Alisa R Paterson and Naresh C Osti and Yangyunli Sun and Simon Fleischmann and Rui Zhang and Louis A Madsen and Michael F Toney and De-en Jiang and Alexander I Kolesnikov and Eugene Mamontov and Veronica Augustyn},

doi = {10.1021/acsenergylett.9b02040},

year  = {2019},

date = {2019-10-29},

journal = {ACS Energy Lett.},

volume = {4},

pages = {2805–2812},

abstract = {There is widespread interest in determining the structural features of redox-active electrochemical energy storage materials that enable simultaneous high power and high energy density. Here, we present the discovery that confined interlayer water in crystalline tungsten oxide hydrates, WO3·nH2O, enables highly reversible proton intercalation at subsecond time scales. By comparing the structural transformation kinetics and confined water dynamics of the hydrates with anhydrous WO3, we determine that the rapid electrochemical proton intercalation is due to the ability of the confined water layers to isolate structural transformations to two dimensions while stabilizing the structure along the third dimension. As a result, these water layers provide both structural flexibility and stability to accommodate intercalation-driven bonding changes. This provides an alternative explanation for the fast energy storage kinetics of materials that incorporate structural water and provides a new strategy for enabling high power and high energy density with redox-active layered materials containing confined fluids.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2019c,

title = {Gyroidal Niobium Sulfide/Carbon Hybrid Monoliths for Electrochemical Energy Storage},

author = {Simon Fleischmann and Tobias S. Dörr and Anna Frank and Stefan W. Hieke and David Doblas-Jimenez and Christina Scheu and Peter W. de Oliveira and Tobias Kraus and Volker Presser},

doi = {10.1002/batt.201900035},

year  = {2019},

date = {2019-06-01},

journal = {Batteries & Supercaps},

volume = {2},

issue = {8},

pages = {668-672},

abstract = {Transition metal dichalcogenides are attractive two-dimensional electrode materials for electrochemical energy storage devices due to their high reversible charge storage capacity. Hybridization of these materials with carbon promises enhanced performance by facilitating the access to reactive sites and extended mechanical stabilization. Herein, we introduce a NbS2/C hybrid material exhibiting a gyroidal microstructure synthesized through macromolecular co-assembly of a tailored block copolymer and an organometallic niobium precursor and subsequent sulfidation. Our synthesis allows the preparation of mechanically stable monoliths with NbS2 nanocrystals engulfed in a highly porous carbon shell. Due to the curvature of the gyroidal structure, abundant reactive sites are exposed that lead to an attractive performance in a lithium-containing electrolyte with a capacity of up to 400 mAh/g.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2019b,

title = {Understanding Interlayer Deprotonation of Hydrogen Titanium Oxide for High-Power Electrochemical Energy Storage},

author = {Simon Fleischmann and Kristina Pfeifer and Mathias Widmaier and Hwirim Shim and Öznil Budak and Volker Presser},

doi = {10.1021/acsaem.9b00363},

year  = {2019},

date = {2019-05-28},

journal = {ACS Appl. Energy Mater.},

volume = {2},

pages = {3633–3641},

abstract = {Negative electrode materials that possess fast lithium insertion kinetics are in high demand for high power lithium-ion batteries and hybrid supercapacitor applications. In this work, hydrogen titanium oxides are synthesized by a proton exchange reaction with sodium titanium oxide, resulting in the H2Ti3O7 phase. We show that a gradual water release in four steps yields intermediate phases of hydrogen titanate with different degrees of interlayer protonation. In addition, a synthesis route using zinc nitrate is explored yielding H2Ti3O7 with a high rutile content. This material dehydrates already at a lower temperature, resulting in a lamellar rutile titania phase. The hydrogen titanate materials with partially protonated interlayers are tested as negative electrodes in a lithium-ion battery and hybrid supercapacitor setup, showing an improved performance compared to the fully protonated phases. The performance in half-cells reaches around 168 mAh/g, with high retention of 42 mAh/g at 10 A/g. This translates to an energy of 88 Wh/kg for a full-cell with a maximum power of 9.2 kW/kg and high cycling stability over 1000 cycles.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Shim2019,

title = {Nanosized Titanium Niobium Oxide/Carbon Electrodes for Lithium-Ion Energy Storage Applications},

author = {Hwirim Shim and Eunho Lim and Simon Fleischmann and Antje Quade and Aura Tolosa and Volker Presser},

doi = {10.1039/C9SE00166B},

year  = {2019},

date = {2019-05-20},

journal = {Sustainable Energy & Fuels},

volume = {3},

issue = {7},

pages = {1776-1789},

abstract = {High demand for safer and more stable lithium-ion batteries brings up the challenge for finding better electrode materials. In this work, we study the functionalities of titanium niobium oxide (TNO)/carbon hybrid materials using carbon onions (OLC) and carbon nanohorns (NS), which are synthesized by well-controlled sol–gel chemistry, for anodes in lithium-ion batteries. We used two different molar ratios of titanium to niobium (1 : 2 and 1 : 5), and we compared the TNO–OLC and TNO–NS hybrid materials to conventional composite electrodes using physically admixed carbon. TNO–OLC-1:2 and TNO–OLC-1:5 nanohybrid materials displayed good electrochemical performance, with initial capacity values of 284 mA h g−1 and 290 mA h g−1, respectively, normalized to the metal oxide mass. Moreover, they maintained 68% (TNO–OLC-1:2) and 69% (TNO–OLC-1:5) of the initial capacity at 1 A g−1, outperforming the carbon nanohorn hybridized and composited electrode which maintained less than 50%. The long-term cycling stability of 800 cycles presents good capacity retention of 73% (TNO–OLC-1:2) and 76% (TNO–OLC-1:5), while the TNO–NS-1:2 hybrid material yields better capacity retention of 90% despite its low capacity. Our study demonstrates that the combination of TNO with appropriate carbon substrates enables good electrochemical performance but requires careful evaluation of the interplay of crystal structure, phase content, and particle morphology.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{and Pattarachaiand Auraand Simonand Juhanand Stefanand Annaand Christinaand VolkerPresser2019,

title = {Vanadium (III) Oxide/Carbon Core/Shell Hybrids as an Anode for Lithium‐Ion Batteries},

author = {Öznil Budak and Pattarachai Srimuk and Aura Tolosa and Simon Fleischmann and Juhan Lee and Stefan W. Hieke and Anna Frank and Christina Scheu and Volker Presser},

doi = {10.1002/batt.201800115},

year  = {2019},

date = {2019-01-04},

journal = {Batteries & Supercaps},

volume = {2},

issue = {1},

pages = {74-82},

abstract = {We present a facile two-step synthesis of vanadium (III) oxide/carbon core/shell hybrid material for application as lithium-ion battery electrode. The first step is a thermal treatment of a mixture of vanadium carbide (VC) and NiCl2 ⋅ 6H2O at 700 °C in an inert gas atmosphere. Elemental nickel obtained from decomposing NiCl2 ⋅ 6H2O served as a catalyst to trigger the local formation of graphitic carbon. In a second step, residual nickel was removed by washing the material in aqueous HCl. By replacing NiCl2 ⋅ 6H2O with anhydrous NiCl2, we obtained a hybrid material of vanadium carbide-derived carbon and a vanadium carbide core. Material characterization revealed a needle-like morphology of the rhombohedral V2O3 along with two carbon species with a different degree of graphitic ordering. We varied the NiCl2 ⋅ 6H2O-to-VC ratio, and the optimized material yielded a capacity of 110 mAh ⋅ g−1 at 2.5 A ⋅ g−1 which increased to 225 mAh ⋅ g−1 at 0.1 A ⋅ g−1 after 500 cycles in the potential range of 0.01-3.00 V vs. Li/Li+. This enhanced performance is in stark contrast to the loss of lithium uptake capacity when using commercially available V2O3 mixed with carbon black, where 93 % of the initial capacity was lost after 50 cycles.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2019,

title = {High voltage asymmetric hybrid supercapacitors using lithium- and sodium-containing ionic liquids},

author = {Simon Fleischmann and Mathias Widmaier and Anna Schreiber and Hwirim Shim and Frank M. Stiemke and Thomas J.S. Schubert and Volker Presser},

doi = {10.1016/j.ensm.2018.06.011},

year  = {2019},

date = {2019-01-03},

journal = {Energy Storage Materials},

volume = {16},

pages = {391-399},

abstract = {Asymmetric hybrid supercapacitors (AHSCs) combine high specific energy and power by merging two electrodes with capacitive and Faradaic charge storage mechanisms. In this study, we introduce AHSC cells that use lithium titanate and activated carbon electrodes in an alkali-ion containing ionic liquid electrolyte. With this cell concept, it is possible to operate the activated carbon electrode in a higher potential window. Consequently, higher cell voltages and a reduced carbon electrode mass can be used, resulting in significantly increased energy compared to aqueous or organic electrolytes. We demonstrate the feasibility of this cell concept for both lithium- and sodium-ion intercalation, underlining the general validity of our approach. Our prototype cells already reach high specific energies of 100 W h/kg, while maintaining a specific power of up to 2 kW/kg and cycling stability of over 1500 cycles. Owing to the IL electrolyte, stable cycling of an AHSC at 80 °C is demonstrated for the first time.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Lee2018,

title = {Redox-electrolytes for non-flow electrochemical energy storage: A critical review and best practice},

author = {Juhan Lee and Pattarachai Srimuk and Simon Fleischmann and Xiao Su and T. Alan Hatton and Volker Presser},

doi = {10.1016/j.pmatsci.2018.10.005},

year  = {2018},

date = {2018-12-11},

urldate = {2022-12-02},

journal = {Progress in Materials Science},

volume = {101},

pages = {46-89},

abstract = {Over recent decades, a new type of electric energy storage system has emerged with the principle that the electric charge can be stored not only at the interface between the electrode and the electrolyte but also in the bulk electrolyte by redox activities of the electrolyte itself. Those redox electrolytes are promising for non-flow hybrid energy storage systems, or redox electrolyte-aided hybrid energy storage (REHES) systems; particularly, when they are combined with highly porous carbon electrodes. In this review paper, critical design considerations for the REHES systems are discussed as well as the effective electrochemical characterization techniques. Appropriate evaluation of the electrochemical performance is discussed thoroughly, including advanced analytical techniques for the determination of the electrochemical stability of the redox electrolytes and self-discharge rate. Additionally, critical summary tables for the recent progress on REHES systems are provided. Furthermore, the unique synergistic combination of porous carbon materials and redox electrolytes is introduced in terms of the diffusion, adsorption, and electrochemical kinetics modulating energy storage in REHES systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Tolosa2018,

title = {Electrospun Hybrid Vanadium Oxide/Carbon Fiber Mats for Lithium- and Sodium-Ion Battery Electrodes},

author = {Aura Tolosa and Simon Fleischmann and Ingrid Grobelsek and Volker Presser},

doi = {10.1021/acsaem.8b00572},

year  = {2018},

date = {2018-12-01},

journal = {ACS Appl. Energy Mater.},

volume = {1},

pages = {3790–3801},

abstract = {Vanadium oxide nanostructures are constantly being researched and developed for cathodes in lithium- and sodium-ion batteries. To improve the internal resistance and the discharge capacity, this study explores the synthesis and characterization of continuous one-dimensional hybrid nanostructures. Starting from a sol–gel synthesis, followed by electrospinning and controlled thermal treatment, we obtained hybrid fibers consisting of metal oxide crystals (orthorhombic V2O5 and monoclinic VO2) engulfed in conductive carbon. For use as Li-ion battery cathode, a higher amount of carbon yields a more stable performance and an improved capacity. Monoclinic VO2/C fibers present a specific capacity of 269 mAh·gVOx–1 and maintain 66% of the initial capacity at a rate of 0.5 A·g–1. Orthorhombic V2O5/C presents a higher specific capacity of 316 mAh·gVOx–1, but a more limited lithium diffusion, leading to a less favorable rate handling. Tested as cathodes for Na-ion batteries, we confirmed the importance of a conductive carbon network and nanostructures for improved electrochemical performance. Orthorhombic V2O5/C hybrid fibers presented very low specific capacity while monoclinic VO2/C fibers presented an improved specific capacity and rate performance with a capacity of 126 mAh·gVOx–1.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2018,

title = {Atomic layer deposited molybdenum oxide / carbon nanotube hybrid electrodes: Influence of crystal structure on lithium-ion capacitor performance},

author = {Simon Fleischmann and Marco Zeiger and Antje Quade and Angela Kruth and Volker Presser},

doi = {10.1021/acsami.8b03233},

year  = {2018},

date = {2018-11-30},

journal = {ACS Appl Mater Interfaces},

volume = {10},

pages = {18675-18684},

abstract = {Merging of supercapacitors and batteries promises the creation of electrochemical energy storage devices that combine high specific energy, power, and cycling stability. For that purpose, lithium-ion capacitors (LICs) that store energy by lithiation reactions at the negative electrode and double-layer formation at the positive electrode are currently investigated. In this study, we explore the suitability of molybdenum oxide as a negative electrode material in LICs for the first time. Molybdenum oxide-carbon nanotube hybrid materials were synthesized via atomic layer deposition, and different crystal structures and morphologies were obtained by post-deposition annealing. These model materials are first structurally characterized and electrochemically evaluated in half-cells. Benchmarking in LIC full-cells revealed the influences of crystal structure, half-cell capacity, and rate handling on the actual device level performance metrics. The energy efficiency, specific energy, and power are mainly influenced by the overpotential and kinetics of the lithiation reaction during charging. Optimized LIC cells show a maximum specific energy of about 70 W·h·kg-1 and a high specific power of 4 kW·kg-1 at 34 W·h·kg-1. The longevity of the LIC cells is drastically increased without significantly reducing the energy by preventing a deep cell discharge, hindering the negative electrode from crossing its anodic potential limit.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{and Hwirimand SimonFleischmann2018,

title = {Fast and stable lithium-ion storage kinetics of anatase titanium dioxide/carbon onion hybrid electrodes},

author = {Eunho Lim and Hwirim Shim and Simon Fleischmann and Volker Presser},

doi = {10.1039/C8TA02293C},

year  = {2018},

date = {2018-11-12},

journal = {Journal of Materials Chemistry A},

volume = {6},

pages = {9480-9488},

abstract = {Research on alternatives to replace conventional graphite anodes is needed to advance lithium-ion battery technology. In this work, an anatase nano-TiO2/carbon onion hybrid material (nano-TiO2–C) is introduced as a rapid and stable lithium storage anode material, synthesized by a simple synthetic route using tailored sol–gel chemistry. The nano-TiO2–C hybrid material provides highly reversible capacity (166 mA h g−1 at 0.02 A g−1), promising rate capability (61 mA h g−1 at 5 A g−1), and long-term cycle stability (capacity retention: 94% at 1 A g−1 for 1000 cycles). We demonstrate that hybridization of nano-TiO2 with carbon onions improves the high rate performance significantly.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Srimuk2018,

title = {Potential-Dependent, Switchable Ion Selectivity in Aqueous Media Using Titanium Disulfide},

author = {Pattarachai Srimuk and Juhan Lee and Simon Fleischmann and Mesut Aslan and Choonsoo Kim and Volker Presser},

doi = {10.1002/cssc.201800452},

year  = {2018},

date = {2018-11-11},

journal = {ChemSusChem},

volume = {11},

issue = {13},

pages = {2091-2100},

abstract = {The selective removal of ions by an electrochemical process is a promising approach to enable various water-treatment applications such as water softening or heavy-metal removal. Ion intercalation materials have been investigated for their intrinsic ability to prefer one specific ion over others, showing a preference for (small) monovalent ions over multivalent species. In this work, we present a fundamentally different approach: tunable ion selectivity not by modifying the electrode material, but by changing the operational voltage. We used titanium disulfide, which shows distinctly different potentials for the intercalation of different cations and formed binder-free composite electrodes with carbon nanotubes. Capitalizing on this potential difference, we demonstrated controllable cation selectivity by online monitoring the effluent stream during electrochemical operation by inductively coupled plasma optical emission spectrometry of aqueous 50 mm CsCl and MgCl2. We obtained a molar selectivity of Mg2+ over Cs+ of 31 (strong Mg preference) in the potential range between −396 mV and −220 mV versus Ag/AgCl. By adjusting the operational potential window from −219 mV to +26 mV versus Ag/AgCl, Cs+ was preferred over Mg2+ by 1.7 times (Cs preference).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2022b,

title = {Design of Carbon/Metal Oxide Hybrids for Electrochemical Energy Storage},

author = {Simon Fleischmann and Aura Tolosa and Volker Presser},

doi = {10.1002/chem.201800772},

year  = {2018},

date = {2018-11-09},

urldate = {2018-08-22},

journal = {Chem. Eur. J.},

volume = {24},

pages = {12143-12153},

abstract = {Next generation electrochemical energy storage materials that enable a combination of high specific energy, specific power, and cycling stability can be obtained by a hybridization approach. This involves electrode materials that contain carbon and metal oxide phases linked on a nanoscopic level and combine characteristics of supercapacitors and batteries. The combination of the components requires careful design to create synergistic effects for an increased electrochemical performance. Improved understanding of the role of carbon as a substrate has advanced the power handling and cycling stability of hybrid materials significantly in recent years. This Concept outlines different design strategies for the design of hybrid electrode materials: (1) the deposition of metal oxides on readily existing carbon substrates and (2) co-synthesizing both carbon and metal oxide phase during the synthesis procedure. The implications of carbon properties on the hybrid material's structure and performance will be assessed and the impact of the hybrid electrode architecture will be analyzed. The advantages and disadvantages of all approaches are highlighted and strategies to overcome the latter will be proposed.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Dörr2017,

title = {Ordered Mesoporous Titania/Carbon Hybrid Monoliths for Lithium‐ion Battery Anodes with High Areal and Volumetric Capacity},

author = {Tobias S. Dörr and Simon Fleischmann and Marco Zeiger and Ingrid Grobelsek and Peter W. de Oliveira and Volker Presser},

doi = {10.1002/chem.201801099},

year  = {2018},

date = {2018-11-06},

urldate = {2018-03-06},

journal = {Chem. Eur. J.},

volume = {24},

issue = {24},

pages = {6358-6363},

abstract = {Free-standing, binder-free, and conductive additive-free mesoporous titanium dioxide/carbon hybrid electrodes were prepared from co-assembly of a poly(isoprene)-block-poly(styrene)-block-poly(ethylene oxide) block copolymer and a titanium alkoxide. By tailoring an optimized morphology, we prepared macroscopic mechanically stable 300 μm thick monoliths that were directly employed as lithium-ion battery electrodes. High areal mass loading of up to 26.4 mg cm−2 and a high bulk density of 0.88 g cm−3 were obtained. This resulted in a highly increased volumetric capacity of 155 mAh cm−3, compared to cast thin film electrodes. Further, the areal capacity of 4.5 mAh cm−2 represented a 9-fold increase compared to conventionally cast electrodes. These attractive performance metrics are related to the superior electrolyte transport and shortened diffusion lengths provided by the interconnected mesoporous nature of the monolith material, assuring superior rate handling, even at high cycling rates.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Rosenkranz2018,

title = {Tip-enhanced Raman spectroscopy studies of nanodiamonds and carbon onions},

author = {Andreas Rosenkranz and Lindsay Freeman and Simon Fleischmann and Federico Lasserre and Yeshaiahu Fainman and Frank E. Talke},

doi = {10.1016/j.carbon.2018.02.088},

year  = {2018},

date = {2018-11-04},

urldate = {2018-06-01},

journal = {Carbon},

volume = {132},

pages = {495-502},

abstract = {Nanodiamond powder was annealed at temperatures ranging between 700 and 1700 °C and deposited by electrophoretic deposition on steel substrates. Far-field Raman spectroscopy and tip-enhanced Raman spectroscopy were used to investigate structural changes after the transformation from nanodiamonds to carbon onions as a function of the annealing temperature. Enhancement of the Raman signal was observed for all samples irrespective of the hybridization state. The largest enhancement on the order of 105 was found for non-annealed nanodiamonds. Far-field Raman spectroscopy and tip-enhanced Raman spectroscopy showed similar results as a function of the annealing temperature for peak position and width of the D- and G-peaks, intensity ratio ID/IG, and area integrated intensity ratio AD/AG.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Tolosa2017,

title = {Binder‐Free Hybrid Titanium–Niobium Oxide/Carbon Nanofiber Mats for Lithium‐Ion Battery Electrodes},

author = {Aura Tolosa and Simon Fleischmann and Ingrid Grobelsek and Antje Quade and Eunho Lim and Volker Presser},

doi = {10.1002/cssc.201701927},

year  = {2018},

date = {2018-11-03},

urldate = {2017-11-03},

journal = {ChemSusChem},

volume = {11},

pages = {159-170},

abstract = {Do not break the fiber mats! This study introduces a one-pot synthesis for free-standing electrodes consisting of electrospun tetragonal niobium oxide/carbon, and monoclinic titanium–niobium oxide/carbon hybrid fibers. The fiber mats are used as polymer-binder- and conductive-additive-free electrodes for Li-ion batteries, with high conductivity and high rate handling performance.

Free-standing, binder-free, titanium–niobium oxide/carbon hybrid nanofibers are prepared for Li-ion battery applications. A one-pot synthesis offers a significant reduction of processing steps and avoids the use of environmentally unfriendly binder materials, making the approach highly sustainable. Tetragonal Nb2O5/C and monoclinic Ti2Nb10O29/C hybrid nanofibers synthesized at 1000 °C displayed the highest electrochemical performance, with capacity values of 243 and 267 mAh g−1, respectively, normalized to the electrode mass. At 5 A g−1, the Nb2O5/C and Ti2Nb10O29/C hybrid fibers maintained 78 % and 53 % of the initial capacity, respectively. The higher rate performance and stability of tetragonal Nb2O5 compared to that of monoclinic Ti2Nb10O29 is related to the low energy barriers for Li+ transport in its crystal structure, with no phase transformation. The improved rate performance resulted from the excellent charge propagation in the continuous nanofiber network.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Choudhury2017,

title = {Carbon onion/sulfur hybrid cathodes via inverse vulcanization for lithium–sulfur batteries},

author = {Soumyadip Choudhury and Pattarachai Srimuk and Kumar Raju and Aura Tolosa and Simon Fleischmann and Marco Zeiger and Kenneth I. Ozoemena and Lars Borchardt and Volker Presser},

doi = {10.1039/C7SE00452D},

year  = {2018},

date = {2018-10-31},

urldate = {2017-10-31},

journal = {Sustainable Energy & Fuels},

volume = {2},

pages = {133-146},

abstract = {A sulfur–1,3-diisopropenylbenzene copolymer was synthesized by ring-opening radical polymerization and hybridized with carbon onions at different loading levels. The carbon onion mixing was assisted by shear in a two-roll mill to capitalize on the softened state of the copolymer. The sulfur copolymer and the hybrids were thoroughly characterized in structure and chemical composition, and finally tested by electrochemical benchmarking. An enhancement of specific capacity was observed over 140 cycles at higher content of carbon onions in the hybrid electrodes. The copolymer hybrids demonstrate a maximum initial specific capacity of 1150 mA h gsulfur−1 (850 mA h gelectrode−1) and a low decay of capacity to reach 790 mA h gsulfur−1 (585 mA h gelectrode−1) after 140 charge/discharge cycles. All carbon onion/sulfur copolymer hybrid electrodes yielded high chemical stability, stable electrochemical performance superior to conventional melt-infiltrated reference samples having similar sulfur and carbon onion content. The amount of carbon onions embedded in the sulfur copolymer has a strong influence on the specific capacity, as they effectively stabilize the sulfur copolymer and sterically hinder the recombination of sulfur species to the S8 configuration.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2022,

title = {Tailored Mesoporous Carbon/Vanadium Pentoxide Hybrid Electrodes for High Power Pseudocapacitive Lithium and Sodium Intercalation},

author = {Simon Fleischmann and Desirée Leistenschneider and Valeria Lemkova and Benjamin Krüner and Marco Zeiger and Lars Borchardt and Volker Presser},

doi = {10.1021/acs.chemmater.7b02533},

year  = {2017},

date = {2017-10-13},

urldate = {2022-10-13},

journal = {Chemistry of Materials},

volume = {29},

pages = {8653–8662},

abstract = {In this study, atomic layer deposition (ALD) is employed to synthesize hybrid electrode materials of especially tailored mesoporous carbon and vanadium oxide. The highly conformal and precise character of ALD allowed for depositing up to 65 mass % of vanadium oxide inside the 5–20 nm mesopores of the carbon particles, without substantially obstructing internal surface area. The deposited phase was identified as orthorhombic V2O5, and an increasing crystalline order was detected for higher mass loadings. Employing the hybrid material as lithium and sodium intercalation hosts at a rate of 0.5C yielded specific capacities of 310 and 250 mAh/g per V2O5, respectively, while showing predominantly pseudocapacitive behavior, that is, capacitor-like voltage profiles. C-rate benchmarking revealed a retention of about 50% of the maximum capacity for both lithium and sodium at a high rate of 100C. When testing for longevity in lithium-containing electrolyte, a steadily increasing capacity was observed to 116% of the initial value after 2000 cycles. In sodium electrolyte, the capacity faded to 75% after 2000 cycles, which represents one of the most stable performances for sodium intercalation in the literature. Homogeneously distributed vanadium oxide that is locally confined in the tailored carbon mesopores was identified as the reason for enhanced cyclability and rate behavior of the hybrid material.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Faradaic deionization of brackish and sea water via pseudocapacitive cation and anion intercalation into few-layered molybdenum disulfide},

author = {Pattarachai Srimuk and Juhan Lee and Simon Fleischmann and Soumyadip Choudhury and Nicolas Jäckel and Marco Zeiger and Choonsoo Kim and Mesut Aslan and Volker Presser},

doi = {10.1039/C7TA03120C},

year  = {2017},

date = {2017-10-03},

journal = {Journal of Materials Chemistry A},

volume = {5},

pages = {15640-15649},

abstract = {This work establishes molybdenum disulfide/carbon nanotube electrodes for the desalination of high molar saline water. Capitalizing on the two-dimensional layered structure of MoS2, both cations and anions can be effectively removed from a feed water stream by faradaic ion intercalation. The approach is based on the setup of capacitive deionization (CDI), where an effluent water stream is desalinated via the formation of an electrical double-layer at two oppositely polarized carbon electrodes. Yet, CDI can only be effectively applied to low concentrated solutions due to the intrinsic limitation of the electrosorption mechanism. By replacing the conventional porous carbon with MoS2/CNT binder-free electrodes, deionization of sodium and chloride ions was achieved by ion intercalation instead of ion electrosorption. This enabled stable desalination performance over 25 cycles in various molar concentrations, with salt adsorption capacities of 10, 13, 18, and 25 mg g−1 in 5, 25, 100, and 500 mM NaCl aqueous solutions, respectively. This novel approach of faradaic deionization (FDI) paves the way towards a more energy-efficient desalination of brackish water and even sea water.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kim2017,

title = {Influence of pore structure and cell voltage of activated carbon cloth as a versatile electrode material for capacitive deionization},

author = {Choonsoo Kim and Pattarachai Srimuk and Juhan Lee and Simon Fleischmann and Mesut Aslan and Volker Presser},

doi = {10.1016/j.carbon.2017.06.077},

year  = {2017},

date = {2017-10-02},

urldate = {2017-10-02},

journal = {Carbon},

volume = {122},

pages = {329-335},

abstract = {Activated carbon cloth is a promising electrode material for capacitive deionization to accomplish energy efficient desalination of water. The most attractive feature is the combination of high porosity and the ability to shape binder-free electrodes by simple cutting. The macroporous inter-fiber space also assists facile flow of the aqueous medium. Our work presents a thorough benchmarking of activated carbon cloth materials with different pore structures which show different potentials at zero charge. The studied activated carbon cloth textiles possess a large microporosity with an average pore size of 0.7–1.3 nm and stable electrochemical performance in aqueous media with specific capacitance of up to 125 F/g. In aqueous 5 mM NaCl, the electrodes achieve up to 16 mg/g salt adsorption capacity with charge efficiency of 80% at cell voltage of 1.2 V. Further on, we investigated cell voltages between 0.6 V and 1.2 V and applied our predictive salt adsorption tool that is based on the pore structure to the entire voltage window range. Our work also shows that activated carbon cloth can even be operated without a current collector.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Lee2017b,

title = {Nanoconfinement of redox reactions enables rapid zinc iodide energy storage with high efficiency},

author = {Juhan Lee and Pattarachai Srimuk and Simon Fleischmann and Alexander Ridder and Marco Zeiger and Volker Presser},

doi = {10.1039/C7TA03589F},

year  = {2017},

date = {2017-06-01},

urldate = {2017-06-01},

journal = {Journal of Materials Chemistry A},

volume = {5},

pages = {12520-12527},

abstract = {A key challenge for present-day electric energy storage systems, such as supercapacitors and batteries, is to meet the world's growing demand for high performances, low cost, and environmental-friendliness. Here, we introduce a hybrid energy storage system combining zinc iodide (ZnI2) as redox electrolyte with a nanoporous activated carbon fiber (ACF) cathode and a zinc disk anode. We found that the nanopores (<1 nm) of ACF lead to a strong adsorption behavior of iodide and triiodide. Hence, this system exhibits low self-discharge rates without applying an ion exchange membrane. The high power performance (20.0 kW kg−1) originates from the enhanced redox kinetics of the iodide system as evidenced by electrochemical analysis. Considering the high specific energy (226 W h kg−1), the ACF/Zn ZnI2 battery represents an alternative for lead acid, Ni–Zn, and Ni–Cd batteries, while providing a supercapacitor-like power performance in the range of seconds to minutes charging times.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2017b,

title = {Tuning pseudocapacitive and battery-like lithium intercalation in vanadium dioxide/carbon onion hybrids for asymmetric supercapacitor anodes},

author = {Simon Fleischmann and Marco Zeiger and Nicolas Jäckel and Benjamin Krüner and Valeria Lemkova and Mathias Widmaier and Volker Presser},

doi = {10.1039/C7TA02564E},

year  = {2017},

date = {2017-05-31},

urldate = {2017-05-31},

journal = {Journal of Materials Chemistry A},

volume = {5},

pages = {13039-13051},

abstract = {The study presents the synthesis of vanadium oxide/carbon onion hybrid materials. Flower-like vanadium oxide nanostructures nucleate on carbon onion nanoparticles under hydrothermal conditions, forming a highly intertwined network. By varying the amount of added carbon onions during the synthesis, the number of possible nucleation sites can be adjusted, resulting in the preferential growth of vanadium dioxide in either P21/c or C2/m space group. When employed as a lithium intercalation electrode, P21/c VO2 exhibits capacitor-like (pseudocapacitive) lithium intercalation, whereas C2/m VO2 shows battery-like intercalation peaks with a maximum capacity of 127 mA h g−1. By selecting an optimum ratio and thereby combining both intercalation mechanisms, enhanced kinetics with discharge capacities of 45 mA h g−1 and 29 mA h g−1 at high rates of 50 A g−1 and 100 A g−1 (equal to 394C and 788C) are obtained. This behavior can be translated to a device level by using the material as anodes in asymmetric supercapacitors with activated carbon cathodes, yielding a maximum specific energy of 45 W h kg−1 and a high power of 58 kW kg−1, while longevity over 5000 charge/discharge cycles is demonstrated.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Krüner2017,

title = { Hydrogen-treated, sub-micrometer carbon beads for fast capacitive deionization with high performance stability},

author = {Benjamin Krüner and Pattarachai Srimuk and Simon Fleischmann and Marco Zeiger and Anna Schreiber and Mesut Aslan and Antje Quade and Volker Presser},

doi = {10.1016/j.carbon.2017.02.054},

year  = {2017},

date = {2017-05-26},

urldate = {2017-06-01},

journal = {Carbon},

volume = {117},

pages = {46-54},

abstract = {Novolac is a low-cost carbon precursor which can be used to derive nanoporous carbon beads in sub-micrometer size. In this study, we introduce this material as a novel electrode material for capacitive deionization (CDI) with high performance stability and superior desalination rate. The polymer beads were synthesized employing a self-emulsifying system in an autoclave, pyrolyzed under argon, and activated with CO2, yielding a specific surface area of 1905 m2 g−1 with a high total pore volume of 1.26 cm3 g−1. After CO2 activation, the material shows a salt sorption capacity of ∼8 mg g−1, but the performance is highly influenced by functional groups, causing an inversion peak and fast performance decay. However, de-functionalization via hydrogen treatment is outlined as an effective strategy to improve the CDI performance. After hydrogen treatment of novolac-derived carbon beads, we obtained a salt sorption capacity of 11.5 mg g−1 with a charge efficiency of more than 80% and a performance stability of around 90% over more than 100 cycles. Particularly attractive for practical application is the very high average salt adsorption rate of 0.104 mg g−1 s−1, outperforming commercial activated carbons, which are commonly used for CDI, by at least a factor of two.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Lee2017,

title = {Asymmetric tin–vanadium redox electrolyte for hybrid energy storage with nanoporous carbon electrodes},

author = {Juhan Lee and Aura Tolosa and Benjamin Krüner and Nicolas Jäckel and Simon Fleischmann and Marco Zeiger and Daekyu Kim and Volker Presser},

doi = {10.1039/C6SE00062B},

year  = {2017},

date = {2017-01-29},

journal = {Sustainable Energy & Fuels},

volume = {1},

pages = {299-307},

abstract = {In recent decades, redox-active electrolytes have been applied in stationary energy storage systems, benefitting from Faradaic reactions of the electrolyte instead of the electrode material. One of the challenging tasks is to balance the redox activities between the negative and positive electrode. As a possible solution, a mixed electrolyte with vanadyl and tin sulfate was previously suggested; however, a low power performance is a great challenge to be overcome. Here, we found that the origin of the poor power performance in the mixture electrolyte system (vanadium complex and tin solution) is the reduction of the pore volume at the positive electrode via irreversible tin dioxide formation. To prevent the latter, we introduce a hybrid energy storage system exhibiting both battery-like and supercapacitor-like features via asymmetric redox electrolytes at the microporous activated carbon electrodes; SnF2 solution as anolyte and VOSO4 as catholyte. By employing an anion exchange membrane, the irreversible SnO2 formation at the positive electrode is effectively suppressed; thus, an asymmetric 1 M SnF2|3 M VOSO4 system provides a high maximum specific power (3.8 kW kg−1 or 1.5 kW L−1), while still exhibiting a high maximum specific energy up to 58.4 W h kg−1 (23.4 W h L−1) and a high cycling stability over 6500 cycles.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Carbon onion–sulfur hybrid cathodes for lithium–sulfur batteries},

author = {Soumyadip Choudhury and Marco Zeiger and Pau Massuti-Ballester and Simon Fleischmann and Petr Formanek and Lars Borchardt and Volker Presser},

doi = {10.1039/C6SE00034G},

year  = {2017},

date = {2017-01-24},

urldate = {2017-01-17},

journal = {Sustainable Energy & Fuels},

volume = {1},

pages = {84-94},

abstract = {In this study, we explore carbon onions (diameter below 10 nm), for the first time, as a substrate material for lithium sulfur cathodes. We introduce several scalable synthesis routes to fabricate carbon onion–sulfur hybrids by adopting in situ and melt diffusion strategies with sulfur fractions up to 68 mass%. The conducting skeleton of agglomerated carbon onions proved to be responsible for keeping active sulfur always in close vicinity to the conducting matrix. Therefore, the hybrids are found to be efficient cathodes for Li–S batteries, yielding 97–98% Coulombic efficiency over 150 cycles with a slow fading of the specific capacity (ca. 660 mA h g−1 after 150 cycles) in long term cycle test and rate capability experiments.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fleischmann2017,

title = {Vanadia–titania multilayer nanodecoration of carbon onions via atomic layer deposition for high performance electrochemical energy storage},

author = {Simon Fleischmann and Aura Tolosa and Marco Zeiger and Benjamin Krüner and Nicolas J. Peter and Ingrid Grobelsek and Antje Quade and Angela Kruth and Volker Presser},

doi = {10.1039/C6TA09890H},

year  = {2017},

date = {2017-01-17},

journal = {Journal of Materials Chemistry A},

volume = {5},

pages = {2792-2801},

abstract = {Atomic layer deposition has proven to be a particularly attractive approach for decorating mesoporous carbon substrates with redox active metal oxides for electrochemical energy storage. This study, for the first time, capitalizes on the cyclic character of atomic layer deposition to obtain highly conformal and atomically controlled decoration of carbon onions with alternating stacks of vanadia and titania. The addition of 25 mass% TiO2 leads to expansion of the VO2 unit cell, thus greatly enhancing lithium intercalation capacity and kinetics. Electrochemical characterization revealed an ultrahigh discharge capacity of up to 382 mA h g−1 of the composite electrode (554 mA h g−1 per metal oxide) with an impressive capacity retention of 82 mA h g−1 (120 mA h g−1 per metal oxide) at a high discharge rate of 20 A g−1 or 52C. Stability benchmarking showed stability over 3000 cycles when discharging to a reduced potential of −1.8 V vs. carbon. These capacity values are among the highest reported for any metal oxide system, while in addition, supercapacitor-like power performance and longevity are achieved. At a device level, high specific energy and power of up to 110 W h kg−1 and 6 kW kg−1, respectively, were achieved when employing the hybrid material as anode versus activated carbon cathode.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Srimuk2017,

title = {Enhanced performance stability of carbon/titania hybrid electrodes during capacitive deionization of oxygen saturated saline water},

author = {Pattarachai Srimuk and Marco Zeiger and Nicolas Jäckel and Aura Tolosa and Benjamin Krüner and Simon Fleischmann and Ingrid Grobelsek and Mesut Aslan and Boris Shvartsev and Matthew E. Suss and Volker Presser},

doi = {10.1016/j.electacta.2016.12.060},

year  = {2017},

date = {2017-01-10},

journal = {Electrochimica Acta},

volume = {224},

pages = {314-328},

abstract = {Capacitive deionization (CDI) is a promising technology for the desalination of brackish water due to its potentially high energy efficiency and its relatively low costs. One of the most challenging issues limiting current CDI cell performance is poor cycling stability. CDI can show highly reproducible salt adsorption capacities (SACs) for hundreds of cycles in oxygen-free electrolyte, but by contrast poor stability when oxygen is present due to a gradual oxidation of the carbon anode. This oxidation leads to increased concentration of oxygen-containing surface functional groups within the micropores of the carbon anode, increasing parasitic co-ion current and decreasing SAC. In this work, activated carbon (AC) was chemically modified with titania to achieve additional catalytic activity for oxygen-reduction reactions on the electrodes, preventing oxygen from participating in carbon oxidation. Using this approach, we show that the SAC can be increased and the cycling stability prolonged in electrochemically highly demanding oxygen-saturated saline media (5 mM NaCl). The electrochemical oxygen reduction reaction (ORR) occurring in our CDI cell was evaluated by the number of electron transfers during charging and discharging. It was found that, depending on the amount of titania, different ORR pathways take place. A loading of 15 mass% titania presents the best CDI performance and also demonstrates a favorable three-electron transfer ORR.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Lee2016,

title = {Porous carbon as a quasi-reference electrode in aqueous electrolytes},

author = {Juhan Lee and Nicolas Jäckel and Daekyu Kim and Mathias Widmaier and S. Sathyamoorthi and Pattarachai Srimuk and Choonsoo Kim and Simon Fleischmann and Marco Zeiger and Volker Presser},

doi = {10.1016/j.electacta.2016.11.148},

year  = {2016},

date = {2016-11-26},

journal = {Electrochimica Acta},

volume = {222},

pages = {1800-1805},

abstract = {This study examines the performance of porous carbon as quasi-reference electrode (QRE) in aqueous media and evaluates their suitability. The performance of activated carbon and carbon black as QRE was investigated in acidic (H2SO4) and neutral (Na2SO4, NaCl, Li2SO4) solutions and compared to platinum metal wire and Ag/AgCl reference electrode. In neutral and acidic electrolyte, the porous carbon based QREs exhibited a notable stability and reliability with low level of potential drift (1 mV per day) and potential deviation of less than 10 mV. These results can contribute to the further development in porous carbon based QREs leading to novel opportunities in electrochemical analysis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Widmaier2016,

title = {Carbon as Quasi-Reference Electrode in Unconventional Lithium-Salt Containing Electrolytes for Hybrid Battery/Supercapacitor Devices},

author = {Mathias Widmaier and Benjamin Krüner and Nicolas Jäckel and Mesut Aslan and Simon Fleischmann and C. Engel and Volker Presser},

doi = {10.1149/2.0421614jes},

year  = {2016},

date = {2016-11-04},

journal = {Journal of The Electrochemical Society},

volume = {163},

number = {14},

pages = {A2956-A2964},

abstract = {Metallic lithium is the most widespread reference electrode in lithium ion battery research, but its high reactivity limits the usage primarily to conventional carbonate based electrolytes. Novel high power concepts, like hybrid supercapacitors, require lithium containing electrolytes with high ionic conductivity (e.g., acetonitrile), which are not always stable versus lithium. In the current work we face this issue by refining activated carbon as a quasi-reference electrode originally employed for conventional supercapacitors. Different commercially available carbon powders were examined as reference electrode materials and calibrated in lithium-salt containing acetonitrile versus Li+ intercalation/de-intercalation reaction of nanoparticulate Li4Ti5O12. The stability of the activated carbon reference electrode is highly affected by the salt employed and decreases in the following order: LiTFSI > LiClO4 > LiPF6 > LiBF4. Only a negligible impact of electrolyte solvent, pore size distribution and reference electrode binder was observed. Furthermore, activated carbon was functionalized (HNO3 treated) and de-functionalized (thermal annealing in vacuum or hydrogen) to investigate the impact of carbon functionalization on the reference electrode stability. Nitrogen and oxygen containing surface groups have been found to drastically improve long-term stability of activated carbon quasi-reference electrodes. Even after 15 days exposed to the electrolyte, the potential of HNO3 treated activated carbon is marginally altered by 10 mV.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Srimuk2016b,

title = {MXene as a novel intercalation-type pseudocapacitive cathode and anode for capacitive deionization},

author = {Pattarachai Srimuk and Friedrich Kaasik and Benjamin Krüner and Aura Tolosa and Simon Fleischmann and Nicolas Jäckel and Mehmet C. Tekeli and Mesut Aslan and Matthew E. Suss and Volker Presser},

doi = {10.1039/C6TA07833H},

year  = {2016},

date = {2016-11-02},

urldate = {2016-11-02},

journal = {Journal of Materials Chemistry A},

volume = {4},

pages = {18265-18271},

abstract = {In this proof-of-concept study, we introduce and demonstrate MXene as a novel type of intercalation electrode for desalination via capacitive deionization (CDI). Traditional CDI cells employ nanoporous carbon electrodes with significant pore volume to achieve a large desalination capacity via ion electrosorption. By contrast, MXene stores charge by ion intercalation between the sheets of its two-dimensional nanolamellar structure. By this virtue, it behaves as an ideal pseudocapacitor, that is, showing capacitive electric response while intercalating both anions and cations. We synthesized Ti3C2-MXene by the conventional process of etching ternary titanium aluminum carbide i.e., the MAX phase (Ti3AlC2) with hydrofluoric acid. The MXene material was cast directly onto the porous separator of the CDI cell without added binder, and exhibited very stable performance over 30 CDI cycles with an average salt adsorption capacity of 13 ± 2 mg g−1.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Srimuk2016,

title = {High performance stability of titania decorated carbon for desalination with capacitive deionization in oxygenated water},

author = {Pattarachai Srimuk and Lucie Ries and Marco Zeiger and Simon Fleischmann and Nicolas Jäckel and Aura Tolosa and Benjamin Krüner and Mesut Aslan and Volker Presser},

doi = {10.1039/C6RA22800C},

year  = {2016},

date = {2016-11-01},

urldate = {2016-11-01},

journal = {RSC Advances},

volume = {6},

pages = {106081-106089},

abstract = {Performance stability in capacitive deionization (CDI) is particularly challenging in systems with a high amount of dissolved oxygen due to rapid oxidation of the carbon anode and peroxide formation. For example, carbon electrodes show a fast performance decay, leading to just 15% of the initial performance after 50 CDI cycles in oxygenated saline solution (5 mM NaCl). We present a novel strategy to overcome this severe limitation by employing nanocarbon particles hybridized with sol–gel-derived titania. In our proof-of-concept study, we demonstrate very stable performance in low molar saline electrolyte (5 mM NaCl) with saturated oxygen for the carbon/metal oxide hybrid (90% of the initial salt adsorption capacity after 100 cycles). The electrochemical analysis using a rotating disk electrode (RDE) confirms the oxygen reduction reaction (ORR) catalytic effect of FW200/TiO2, preventing local peroxide formation by locally modifying the oxygen reduction reaction.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}