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- ItemTime‐Dependent Cation Selectivity of Titanium Carbide MXene in Aqueous Solution(Weinheim : Wiley-VCH, 2022) Wang, Lei; Torkamanzadeh, Mohammad; Majed, Ahmad; Zhang, Yuan; Wang, Qingsong; Breitung, Ben; Feng, Guang; Naguib, Michael; Presser, VolkerElectrochemical ion separation is a promising technology to recover valuable ionic species from water. Pseudocapacitive materials, especially 2D materials, are up-and-coming electrodes for electrochemical ion separation. For implementation, it is essential to understand the interplay of the intrinsic preference of a specific ion (by charge/size), kinetic ion preference (by mobility), and crystal structure changes. Ti3C2Tz MXene is chosen here to investigate its selective behavior toward alkali and alkaline earth cations. Utilizing an online inductively coupled plasma system, it is found that Ti3C2Tz shows a time-dependent selectivity feature. In the early stage of charging (up to about 50 min), K+ is preferred, while ultimately Ca2+ and Mg2+ uptake dominate; this unique phenomenon is related to dehydration energy barriers and the ion exchange effect between divalent and monovalent cations. Given the wide variety of MXenes, this work opens the door to a new avenue where selective ion-separation with MXene can be further engineered and optimized.
- ItemMechanically Stable, Binder‐Free, and Free‐Standing Vanadium Trioxide/Carbon Hybrid Fiber Electrodes for Lithium‐Ion Batteries(Weinheim : Wiley-VCH, 2023) Bornamehr, Behnoosh; Gallei, Markus; Husmann, Samantha; Presser, VolkerBinder is a crucial component in present-day battery electrodes but commonly contains fluorine and requires coating processing using organic (often toxic) solvents. Preparing binder-free electrodes is an attractive strategy to make battery electrode production and its end-of-use waste greener and safer. Herein, electrospinning is employed to prepare binder-free and self-standing electrodes. Such electrodes often suffer from low flexibility, and the correlation between performance and flexibility is usually overlooked. Processing parameters affect the mechanical properties of the electrodes, and for the first time it is reported that mechanical flexibility directly influences the electrochemical performance of the electrode. The importance is highlighted when processing parameters advantageous to powder materials, such as a higher heat treatment temperature, harm self-standing electrodes due to deterioration of fiber flexibility. Other strategies, such as conductive carbon addition, can be employed to improve the cell performance, but their effect on the mechanical properties of the electrodes must be considered. Rapid heat treatment achieves self-standing V2O3 with a capacity of 250 mAh g−1 at 250 mA g−1 and 390 mAh g−1 at 10 mA g−1
- ItemMixed Cu-Fe Sulfides Derived from Polydopamine-Coated Prussian Blue Analogue as a Lithium-Ion Battery Electrode(Washington, DC : ACS Publications, 2022) Bornamehr, Behnoosh; Presser, Volker; Husmann, SamanthaBatteries employing transition-metal sulfides enable high-charge storage capacities, but polysulfide shuttling and volume expansion cause structural disintegration and early capacity fading. The design of heterostructures combining metal sulfides and carbon with an optimized morphology can effectively address these issues. Our work introduces dopamine-coated copper Prussian blue (CuPB) analogue as a template to prepare nanostructured mixed copper-iron sulfide electrodes. The material was prepared by coprecipitation of CuPB with in situ dopamine polymerization, followed by thermal sulfidation. Dopamine controls the particle size and favors K-rich CuPB due to its polymerization mechanism. While the presence of the coating prevents particle agglomeration during thermal sulfidation, its thickness demonstrates a key effect on the electrochemical performance of the derived sulfides. After a two-step activation process during cycling, the C-coated KCuFeS2electrodes showed capacities up to 800 mAh/g at 10 mA/g with nearly 100% capacity recovery after rate handling and a capacity of 380 mAh/g at 250 mA/g after 500 cycles.
- ItemSelf-Activation of Inorganic-Organic Hybrids Derived through Continuous Synthesis of Polyoxomolybdate and para-Phenylenediamine Enables Very High Lithium-Ion Storage Capacity(Weinheim : Wiley-VCH, 2023) Mohamed, Mana Abdirahman; Arnold, Stefanie; Janka, Oliver; Quade, Antje; Presser, Volker; Kickelbick, GuidoInorganic-organic hybrid materials with redox-active components were prepared by an aqueous precipitation reaction of ammonium heptamolybdate (AHM) with para-phenylenediamine (PPD). A scalable and low-energy continuous wet chemical synthesis process, known as the microjet process, was used to prepare particles with large surface area in the submicrometer range with high purity and reproducibility on a large scale. Two different crystalline hybrid products were formed depending on the ratio of molybdate to organic ligand and pH. A ratio of para-phenylenediamine to ammonium heptamolybdate from 1 : 1 to 5 : 1 resulted in the compound [C6H10N2]2[Mo8O26] ⋅ 6 H2O, while higher PPD ratios from 9 : 1 to 30 : 1 yielded a composition of [C6H9N2]4[NH4]2[Mo7O24] ⋅ 3 H2O. The electrochemical behavior of the two products was tested in a battery cell environment. Only the second of the two hybrid materials showed an exceptionally high capacity of 1084 mAh g−1 at 100 mA g−1 after 150 cycles. The maximum capacity was reached after an induction phase, which can be explained by a combination of a conversion reaction with lithium to Li2MoO4 and an additional in situ polymerization of PPD. The final hybrid material is a promising material for lithium-ion battery (LIB) applications.
- ItemIonophobicity of carbon sub-nanometer pores enables efficient desalination at high salinity(Maryland Heights, MO : Cell Press, 2022) Zhang, Yuan; Prehal, Christian; Jiang, Huili; Liu, Yang; Feng, Guang; Presser, VolkerElectrochemical seawater desalination has drawn significant attention as an energy-efficient technique to address the global issue of water remediation. Microporous carbons, that is, carbons with pore sizes smaller than 2 nm, are commonly used for capacitive deionization. However, micropores are ineffective for capacitive deionization at high molar strength because of their inability to permselectively uptake ions. In our work, we combine experimental work with molecular dynamics simulation and reveal the ability of sub-nanometer pores (ultramicropores) to effectively desalinate aqueous media at seawater-like molar strength. This is done without any ion-exchange membrane. The desalination capacity in 600 mM reaches 12 mg/g, with a charge efficiency of 94% and high cycling stability over 200 cycles (97% of charge efficiency retention). Using molecular dynamic simulations and providing experimental data, our work makes it possible both to understand and to calculate desalination capacity and charge efficiency at high molar strength as a function of pore size.
- ItemBest practice for electrochemical water desalination data generation and analysis(Maryland Heights, MO : Cell Press, 2023) Torkamanzadeh, Mohammad; Kök, Cansu; Burger, Peter Rolf; Ren, Panyu; Zhang, Yuan; Lee, Juhan; Kim, Choonsoo; Presser, VolkerElectrochemical desalination shows promise for ion-selective, energy-efficient water desalination. This work reviews performance metrics commonly used for electrochemical desalination. We provide a step-by-step guide on acquiring, processing, and calculating raw desalination data, emphasizing informative and reliable figures of merit. A typical experiment uses calibrated conductivity probes to relate measured conductivity to concentration. Using a standard electrochemical desalination cell with activated carbon electrodes, we demonstrate the calculation of desalination capacity, charge efficiency, energy consumption, and ion selectivity metrics. We address potential pitfalls in performance metric calculations, including leakage current (charge) considerations and aging of conductivity probes, which can lead to inaccurate results. The relationships between pH, temperature, and conductivity are explored, highlighting their influence on final concentrations. Finally, we provide a checklist for calculating performance metrics and planning electrochemical desalination tests to ensure accuracy and reliability. Additionally, we offer simplified spreadsheet tools to aid data processing, system design, estimations, and upscaling.
- ItemThermo-Responsive Ultrafiltration Block Copolymer Membranes Based on Polystyrene-block-poly(diethyl acrylamide)(Weinheim : Wiley-VCH GmbH, 2023) Frieß, Florian V.; Hartmann, Frank; Gemmer, Lea; Pieschel, Jens; Niebuur, Bart‐Jan; Faust, Matthias; Kraus, Tobias; Presser, Volker; Gallei, MarkusWithin the present work, a thermo-responsive ultrafiltration membrane is manufactured based on a polystyrene-block-poly(diethyl acrylamide) block copolymer (BCP). The poly(diethyl acrylamide) block segment features a lower critical solution temperature (LCST) in water, similar to the well-known poly(N-isopropylacrylamide), but having increased biocompatibility and without exhibiting a hysteresis of the thermally induced switching behavior. The BCP is synthesized via sequential “living” anionic polymerization protocols and analyzed by 1H-NMR spectroscopy, size exclusion chromatography, and differential scanning calorimetry. The resulting morphology in the bulk state is investigated by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) revealing the intended hexagonal cylindrical morphology. The BCPs form micelles in a binary mixture of tetrahydrofuran and dimethylformamide, where BCP composition and solvent affinities are discussed in light of the expected structure of these micelles and the resulting BCP membrane formation. The membranes are manufactured using the non-solvent induced phase separation (NIPS) process and are characterized via scanning electron microscopy (SEM) and water permeation measurements. The latter are carried out at room temperature and at 50 °C revealing up to a 23-fold increase of the permeance, when crossing the LCST of the poly(diethyl acrylamide) block segment in water.
- ItemP2-type layered high-entropy oxides as sodium-ion cathode materials(Bristol : IOP Science, 2022) Wang, Junbo; Dreyer, Sören L; Wang, Kai; Ding, Ziming; Diemant, Thomas; Karkera, Guruprakash; Ma, Yanjiao; Sarkar, Abhishek; Zhou, Bei; Gorbunov, Mikhail V; Omar, Ahmad; Mikhailova, Daria; Presser, Volker; Fichtner, Maximilian; Hahn, Horst; Brezesinski, Torsten; Breitung, Ben; Wang, QingsongP2-type layered oxides with the general Na-deficient composition NaxTMO2 (x < 1, TM: transition metal) are a promising class of cathode materials for sodium-ion batteries. The open Na+ transport pathways present in the structure lead to low diffusion barriers and enable high charge/discharge rates. However, a phase transition from P2 to O2 structure occurring above 4.2 V and metal dissolution at low potentials upon discharge results in rapid capacity degradation. In this work, we demonstrate the positive effect of configurational entropy on the stability of the crystal structure during battery operation. Three different compositions of layered P2-type oxides were synthesized by solid-state chemistry, Na0.67(Mn0.55Ni0.21Co0.24)O2, Na0.67(Mn0.45Ni0.18Co0.24Ti0.1Mg0.03)O2 and Na0.67(Mn0.45Ni0.18Co0.18Ti0.1Mg0.03Al0.04Fe0.02)O2 with low, medium and high configurational entropy, respectively. The high-entropy cathode material shows lower structural transformation and Mn dissolution upon cycling in a wide voltage range from 1.5 to 4.6 V. Advanced operando techniques and post-mortem analysis were used to probe the underlying reaction mechanism thoroughly. Overall, the high-entropy strategy is a promising route for improving the electrochemical performance of P2 layered oxide cathodes for advanced sodium-ion battery applications.
- ItemSelective Pb2+ removal and electrochemical regeneration of fresh and recycled FeOOH([Erscheinungsort nicht ermittelbar] : Tsinghua Press, 2023) Wang, Lei; Deligniere, Lexane; Husmann, Samantha; Leiner, Regina; Bahr, Carsten; Zhang, Shengjie; Dun, Chaochao; Montemore, Matthew M.; Gallei, Markus; Urban, Jeffrey J.; Kim, Choonsoo; Presser, VolkerHeavy metal pollution is a key environmental problem. Selectively extracting heavy metals could accomplish water purification and resource recycling simultaneously. Adsorption is a promising approach with a facile process, adaptability for the broad concentration of feed water, and high selectivity. However, the adsorption method faces challenges in synthesizing high-performance sorbents and regenerating adsorbents effectively. FeOOH is an environmentally friendly sorbent with low-cost production on a large scale. Nevertheless, the selectivity behavior and regeneration of FeOOH are seldom studied. Therefore, we investigated the selectivity of FeOOH in a mixed solution of Co2+, Ni2+, and Pb2+ and proposed to enhance the capacity of FeOOH and regenerate it by using external charges. Without charge, the FeOOH electrode shows a Pb2+ uptake capacity of 20 mg/g. After applying a voltage of −0.2/+0.8 V, the uptake capacity increases to a maximum of 42 mg/g and the desorption ratio is 70%–80%. In 35 cycles, FeOOH shows a superior selectivity towards Pb2+ compared with Co2+ and Ni2+, with a purity of 97% ± 3% in the extracts. The high selectivity is attributed to the lower activation energy for Pb2+ sorption. The capacity retentions at the 5th and the 35th cycles are ca. 80% and ca. 50%, respectively, comparable to the chemical regeneration method. With industrially exhausted granular ferric hydroxide as the electrode material, the system exhibits a Pb2+ uptake capacity of 37.4 mg/g with high selectivity. Our work demonstrates the feasibility of regenerating FeOOH by charge and provides a new approach for recycling and upcycling FeOOH sorbent. [Figure not available: see fulltext.]
- ItemDesign of high-performance antimony/MXene hybrid electrodes for sodium-ion batteries(London [u.a.] : RSC, 2022) Arnold, Stefanie; Gentile, Antonio; Li, Yunjie; Wang, Qingsong; Marchionna, Stefano; Ruffo, Riccardo; Presser, VolkerDue to their versatile properties and excellent electrical conductivity, MXenes have become attractive materials for alkali metal-ion batteries. However, as the capacity is limited to lower values due to the intercalation mechanism, these materials can hardly keep up in the ever-fast-growing community of battery research. Antimony has a promisingly high theoretical sodiation capacity characterized by an alloying reaction. The main drawback of this type of battery material is related to the high volume changes during cycling, often leading to electrode cracking and pulverization, resulting in poor electrochemical performance. A synergistic effect of combing antimony and MXene can be expected to obtain an optimized electrochemical system to overcome capacity fading of antimony while taking advantage of MXene charge storage ability. In this work, variation of the synthesis parameters and material design strategy have been dedicated to achieving the optimized antimony/MXene hybrid electrodes for high-performance sodium-ion batteries. The optimized performance does not align with the highest amount of antimony, the smallest nanoparticles, or the largest interlayer distance of MXene but with the most homogeneous distribution of antimony and MXene while both components remain electrochemically addressable. As a result, the electrode with 40 mass% MXene, not previously expanded, etched with 5 mass% HF and 60% antimony synthesized on the surfaces of MXene emerged as the best electrode. We obtained a high reversible capacity of 450 mA h g−1 at 0.1 A g−1 with a capacity retention of around 96% after 100 cycles with this hybrid material. Besides the successful cycling stability, this material also exhibits high rate capability with a capacity of 365 mA h g−1 at 4 A g−1. In situ XRD measurements and post mortem analysis were used to investigate the reaction mechanism.