Article
Chemistry, Physical
Jungyeon Ji, Chanho Noh, Mingyu Shin, Seunghye Oh, Yongjin Chung, Yongchai Kwon, Do-Heyoung Kim
Summary: A new and economical mesoporous nitrogen-doped carbon structure was prepared using sodium citrate and urea precursors and doped onto graphite felt electrodes. The catalytic properties of the doped electrode were compared with pristine graphite felt and sodium citrate-doped graphite felt electrodes. The results showed that the SC/U-GF electrode exhibited excellent catalytic activity and improved reactivity and reversibility of redox reactions.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Song-Yu Chen, Yu-Lin Kuo, Yao-Ming Wang, Wei-Mau Hsu, Tzu-Hsuan Chien, Chiu-Feng Lin, Cheng-Hsien Kuo, Akitoshi Okino, Tai-Chin Chiang
Summary: Commercial graphite felt (GF) is used as electrodes and coated with a polydopamine catalyst to enhance the electrocatalytic activity for the redox reaction of vanadium ions in vanadium redox flow battery (VRFB). Through a facile coating using atmospheric pressure plasma jet (APPJ), the surface superhydrophilicity is altered and more active sites are provided on the modified electrodes, leading to improved electrochemical performance. The technique of APPJ coating offers oxygen-containing functional groups on the substrate surface for hydrogen bonding with grafted polymeric materials.
Article
Chemistry, Physical
Justyna Piwek, Gabriel Gonzalez, Pekka Peljo, Elzbieta Frackowiak
Summary: In this study, carbon felt electrodes were chemically treated with an alkali metal salt to improve their electrochemical performance. The results showed that the chemically treated electrodes exhibited better performance with lower overpotentials and higher efficiencies. Additionally, the oxidation time of the electrodes could be significantly reduced by using a nitrate salt oxidation method.
Article
Chemistry, Physical
Minseong Kim, Jeongmok Park, Gyuchan Yeo, Minseong Ko, Haeseong Jang
Summary: In this study, a novel strategy was proposed for uniformly implanting multiwall carbon nanotubes in electrode materials such as graphite felt, to develop efficient electron-networked electrodes. The weed root-like morphology of the electrode improved the charge transfer ability and minimized the increase in overpotential even after 1000 cycles of stability test. Therefore, the proposed CNT implanted electrode can be used as an alternative design in practically feasible vanadium redox flow batteries, exhibiting sustainable electrochemical performance.
Article
Materials Science, Multidisciplinary
Qing-Chun Jiang, Jin Li, Yu-Jie Yang, Yu-Jie Ren, Lei Dai, Jia-Yi Gao, Ling Wang, Jia-Ye Ye, Zhang-Xing He
Summary: SnO2 with controllable structure is uniformly distributed on the surface of graphite felt by hydrothermal method and thermal treatment using Sn-MOF as precursor. This composite electrode provides stable active centers for redox reactions, resulting in high energy efficiency and good cycle stability in vanadium redox flow battery.
Article
Chemistry, Physical
Seong Eun Park, So Yeon Yang, Ki Jae Kim
Summary: Boron-doped carbon felt is proposed as a promising electrode for vanadium redox flow batteries, with enhanced affinity with electrolytes and improved energy efficiency attributed to its enhanced electrocatalytic properties towards redox reactions.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
Hongwei Li, Huina Wang, Yueyang Xie, Yukun Wang, Guanghong Yan, Bin Wang, Fei Xue
Summary: In this study, oxygen and nitrogen doping in graphite felt (GF) was achieved through Fe etching and nitrogen functionalization using K2FeO4 and NH3. The modified GF showed enhanced disordered structure and increased oxygen and nitrogen functional groups. The energy efficiency of the modified GF electrode remained at 81.8% after 50 charge-discharge cycles, indicating improved performance of the VRFB.
Article
Chemistry, Physical
Andrea Trovo, Walter Zamboni, Massimo Guarnieri
Summary: An original multichannel Electrochemical Impedance Spectroscopy (EIS) system suitable for high-power Vanadium Redox Flow Batteries (VRFBs) was presented, with a dynamic Thévenin equivalent circuit identified for each cell in the stack. The resistance of the RC loop was found to be strongly affected by mass transport, indicating potential for advanced online state of health monitoring of industrial flow batteries.
JOURNAL OF POWER SOURCES
(2021)
Article
Chemistry, Physical
Ting Long, Yong Long, Mei Ding, Zhizhao Xu, Jian Xu, Yiqiong Zhang, Mingliang Bai, Qijun Sun, Gen Chen, Chuankun Jia
Summary: In this study, a large area graphene modified carbon felt electrode was successfully prepared by chemical vapor deposition, which significantly improved the electrochemical performance of vanadium redox flow batteries. The graphene decoration provided abundant active sites for redox reactions, resulting in enhanced voltage efficiency and energy efficiency compared to pristine carbon felt electrodes. Additionally, the high retention value over 600 cycles demonstrates the promising potential of this electrode for next-generation VRFBs.
Article
Chemistry, Physical
Sieun Jeon, Heeyeon An, Chanho Noh, Yongchai Kwon, Yongjin Chung
Summary: The MTMO (modified TEMPO mediated oxidation) process was used to increase the carboxylic acid group (COOH) content on the surface of lower crystallinity carbon materials (LCCMs), resulting in improved hydrophilicity without defects. The process is environmentally friendly and has advantages such as a recyclable oxidizing agent and room-temperature aqueous treatment. The MTMO-GF electrodes showed improved performance in vanadium ion redox reaction and vanadium redox flow battery tests, with higher current densities and lower charge transfer resistance compared to CH-GF electrodes.
APPLIED SURFACE SCIENCE
(2023)
Review
Energy & Fuels
Nana Zhao, Alison Platt, Harry Riley, Ruoxi Qiao, Roberto Neagu, Zhiqing Shi
Summary: Vanadium redox flow batteries (VRFBs) are the most promising and commercially exploited flow batteries for stationary electrical energy storage. However, there is a lack of ion exchange membranes (IEMs) with higher ion selectivity in the market. This review evaluates the requirements and various modification strategies for IEMs in VRFBs and provides recommendations for future exploration and optimization.
JOURNAL OF ENERGY STORAGE
(2023)
Article
Chemistry, Physical
Wen-Fei Liu, Kue-Ho Kim, Hyo-Jin Ahn
Summary: In recent years, vanadium redox flow batteries (VRFBs) have gained global attention due to their advantages of large scale, high safety, and long-term cyclability. However, the unsatisfactory kinetics of carbon-based anodes, especially graphite felt (GF), hinders the commercial application of VRFBs. To address this issue, a lamination layer of Nb-doped TiO2 (NTO) is introduced to a heat-treated graphite felt (HGF), which improves the surface properties of GF anodes and enables superior energy storage performance compared with other electrodes. The NTO-HGF anode demonstrates a higher energy efficiency of 82.03% compared to pristine GF.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Engineering, Environmental
Zhengyu Hu, Zhiqiang Miao, Zhizhao Xu, Xiaobo Zhu, Fangfang Zhong, Mei Ding, Jianhui Wang, Xiaoyin Xie, Chuankun Jia, Jinlong Liu
Summary: Researchers propose a strategy to improve the electrochemical performance of carbon felt (CF) electrodes by modifying them with cost-effective biomass materials. The optimized biomass-modified CF electrode showed high energy efficiency and outstanding cycling stability in vanadium redox flow batteries (VRFBs).
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Chemistry, Physical
Yi-Hung Wang, I-Ming Hung, Cheng-Yeou Wu
Summary: This study explored a new method of preparing an electrode for a vanadium redox flow battery by depositing vanadium precursor on the surface of graphite felt and calcining vanadium oxide. After testing, it was found that the activated graphite felt showed good capacity utilization and capacity retention in the battery.
Article
Chemistry, Physical
Daniel Manaye Kabtamu, Yu-Zhen Li, Anteneh Wodaje Bayeh, Yun-Ting Ou, Zih-Jhong Huang, Tai-Chin Chiang, Hsin-Chih Huang, Chen-Hao Wang
Summary: This paper presents the successful fabrication of a low-cost platelike bismuth vanadate (BiVO4) material through a simple hydrothermal route, which is used as an electrocatalyst for the negative electrode in vanadium redox flow batteries (VRFBs). The BiVO4-decorated graphite felt (GF) electrode exhibits optimal electrocatalytic activity and reversibility for the redox reactions. The VRFB cell assembled with BiVO4-GF as the negative electrode demonstrates higher energy efficiency and stability compared to the cell with a heat-treated graphite felt (HT-GF) electrode.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Chemistry, Physical
Ijaz Ul Mohsin, Luca Schneider, Marcel Haeringer, Carlos Ziebert, Magnus Rohde, Werner Bauer, Helmut Ehrenberg, Hans Jueergen Seifert
Summary: In this study, Na3V2(PO4)3/C cathode and commercial hard carbon anode materials were coated on an aluminum current collector using a roll-to-roll coater. The degradation mechanism, cycle stability, morphology of cycle-aged material, and aging influence on heat generation during cycling were investigated. The results provide valuable insights for the development of sodium-ion batteries.
JOURNAL OF POWER SOURCES
(2022)
Article
Chemistry, Multidisciplinary
Jinniu Chen, Yang Yang, Yushu Tang, Yifan Wang, Hang Li, Xianghui Xiao, Suning Wang, Mariyam Susana Dewi Darma, Martin Etter, Alexander Missyul, Akhil Tayal, Michael Knapp, Helmut Ehrenberg, Sylvio Indris, Weibo Hua
Summary: The provided lithium content can create a self-protective disordered surface which alleviates oxygen loss and suppresses detrimental phase transitions.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Inorganic & Nuclear
Sunil Kumar, Selvakumar Arumugam, Bjoern Schwarz, Helmut Ehrenberg, Kartik Chandra Mondal
Summary: A representative Co(II) based single ion magnet (SIM) with N2O2 donor set and distorted pseudo-tetrahedral geometry has been synthesized and characterized. The atomic and electronic structure have been studied through DC magnetometry, ab-initio multi-reference CASSCF calculations, and qualitative ligand field theory. AC magnetometry has been used for the investigation of spin-lattice relaxation with temperature and magnetic field variations.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Engineering, Chemical
Chizoom N. Onwucha, Samuel O. Ajayi, Mareen Schaefer, Sylvio Indris, Helmut Ehrenberg, Cyril O. Ehi-Eromosele
Summary: Uncatalyzed neutral hydrolysis of waste PET bottles can completely depolymerize them to produce high purity TPA without any complex separation or purification steps. The effects of hydrolysis time, addition of ethylene glycol cosolvent, and PET/water ratio on TPA yield and purity were investigated. The results showed that a long hydrolysis time, in the absence of any catalyst and a very high PET/water ratio, favored increased TPA yield, selectivity, and purity.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Multidisciplinary Sciences
Kai Wang, Weibo Hua, Xiaohui Huang, David Stenzel, Junbo Wang, Ziming Ding, Yanyan Cui, Qingsong Wang, Helmut Ehrenberg, Ben Breitung, Christian Kuebel, Xiaoke Mu
Summary: High entropy oxides (HEOs) with chemically disordered multi-cation structure have attracted significant attention as negative electrode materials for batteries. However, the mechanisms behind their outstanding electrochemical performance and the so-called 'cocktail effect' have not been fully understood. In this study, the authors investigate the behavior of each element in the HEO Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O during electrochemical reaction and connect it to the nanoscale structure, revealing the multi-cations synergy and explaining the 'cocktail effect'. The findings demonstrate the importance of elemental diversity in optimizing multi-cation electrode materials for batteries.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Nazar Pavlyuk, Grygoriy Dmytriv, Volodymyr Pavlyuk, Wojciech Ciesielski, Beata Rozdzynska-Kielbik, Sylvio Indris, Helmut Ehrenberg
Summary: Crystal structures of MgCoGa, Mg0.74CoGa0.52, and Mg0.49CoGa0.15 phases from the Mg-Co-Ga system were investigated. These structures belong to the Laves phase family. MgCoGa crystallizes as a disordered phase in the MgZn2 structure type. Mg0.74CoGa0.52 has an orthorhombic structure related to MgZn2 and URe2, demonstrated by a Barnighausen formalism group-subgroup transformation scheme. The trigonal phase Mg0.49CoGa0.15 is strongly disordered, with two subcells obtained in a ratio of 9:1, and subcell A is closely related to MgZn2.
ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE CRYSTAL ENGINEERING AND MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Oleksandr Dolotko, Niclas Gehrke, Triantafillia Malliaridou, Raphael Sieweck, Laura Herrmann, Bettina Hunzinger, Michael Knapp, Helmut Ehrenberg
Summary: The authors report a highly efficient mechanochemically induced acid-free recycling method for lithium from different cathode materials, including LiCoO2, LiMn2O4, Li(CoNiMn)O-2, and LiFePO4. The technology uses aluminum as a reducing agent to regenerate lithium and transform it into pure Li2CO3. With a recovery rate of up to 70%, this method does not require corrosive reagents or high temperatures.
COMMUNICATIONS CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Asma'u I. Gebi, Oleksandr Dolokto, Liuda Mereacre, Udo Geckle, Hannes Radinger, Michael Knapp, Helmut Ehrenberg
Summary: There is growing interest in solid-state electrolytes due to their promising properties, making them key to the future of battery technology. This study investigates a time efficient alternative processing route for the synthesis of a promising sodium solid electrolyte, and demonstrates its stability and high conductivity.
Article
Chemistry, Multidisciplinary
Fatemehsadat Rahide, Krishnaveni Palanisamy, Jackson K. Flowers, Junjie Hao, Helge S. Stein, Christine Kranz, Helmut Ehrenberg, Sonia Dsoke
Summary: The naturally occurring amorphous Al2O3 film on an Al substrate poses a challenge for the performance of rechargeable Al batteries. This insulating Al oxide slows down electrode activation and hinders Al plating/stripping. The two sides of Al foils have different surface properties, with the non-shiny side having higher roughness and greater concentration of active sites. Various immersion pretreatments can modify the surface properties and create an interphase layer rich in Al, Cl, and N.
Article
Chemistry, Multidisciplinary
Qiang Fu, Bingrui Guo, Weibo Hua, Angelina Sarapulova, Lihua Zhu, Peter G. G. Weidler, Alexander Missyul, Michael Knapp, Helmut Ehrenberg, Sonia Dsoke
Summary: In this study, the electrochemical properties and reaction mechanism of Li3-2xCaxV2(PO4)(3)/C as negative electrode materials for sodium-ion/potassium-ion batteries were investigated. It was found that the Ca content influenced the diffusion-controlled and pseudocapacitive-type processes in the batteries. Li3V2(PO4)(3)/C showed the highest reversible capacity, while Ca1.5V2(PO4)(3)/C exhibited the best rate performance. It was also discovered that the specific capacity of the material did not increase with Ca-content, but the stability and performance at high C-rate improved by replacing Li+ with Ca2+.
Article
Chemistry, Physical
Clarissa Glaser, Zhixuan Wei, Sylvio Indris, Philip Klement, Sangam Chatterjee, Helmut Ehrenberg, Zhirong Zhao-Karger, Marcus Rohnke, Juergen Janek
Summary: Magnesium batteries have promising potential as next-generation sustainable energy-storage solutions. This study confirms magnesium-ion transport in MgSc2Se4 using two independent electrochemical methods and provides an effective approach for accurately measuring the ionic conductivity.
ADVANCED ENERGY MATERIALS
(2023)
Article
Electrochemistry
Margot Guidat, Fatemehsadat Rahide, Mario Loew, Jongmin Kim, Helmut Ehrenberg, Sonia Dsoke, Matthias M. May
Summary: This study reported the use of reflection anisotropy spectroscopy (RAS) as an in situ characterization technique for non-aqueous battery systems, specifically AlBs. It demonstrated the changes in the solid-electrolyte interface structure during operation conditions and showed the applicability of RAS in monitoring phenomena such as plating/stripping and surface passivation in real-time.
BATTERIES & SUPERCAPS
(2023)
Article
Materials Science, Multidisciplinary
Bjoern Schwarz, Julian Hansen, Anna-Lena Hansen, Eugen Zemlyanushin, Helmut Ehrenberg
Summary: The magnetic properties of tetragonal α-Mn3O4 spinel, its metastable high-pressure modification γ-Mn3O4, and a defect-rich α-Mn3O4 modification were investigated. The unintentional formation of defect-rich α-Mn3O4 phase instead of desired γ-Mn3O4 occurred after high-pressure treatment. The results provide clarification for contradictory reports on the magnetic properties of γ-Mn3O4 in the literature. In addition, in situ low-temperature X-ray diffraction and X-ray absorption spectroscopy experiments did not observe any structural transition coupled with the magnetic transition at 210 K, contradicting previous conclusions based on powder neutron diffraction.
Article
Chemistry, Physical
Francesco Colombo, Marcus Mueller, Andreas Weber, Noah Keim, Fabian Jeschull, Werner Bauer, Helmut Ehrenberg
Summary: This study demonstrates the use of lithium electrolyte salts as slurry additives to achieve high solid content slurries and control slurry gelation. By studying different types of additives and their affinity towards the NMC622 surface, it was found that LiTFA has the best gelation controlling capabilities, while LiTFSI has enhanced long-term capacity retention among the additives.
Article
Chemistry, Multidisciplinary
Adrian Lindner, Hannes Radinger, Frieder Scheiba, Helmut Ehrenberg
Summary: Thermal activation of graphite felts is a valuable technique for improving the reaction kinetics of electrodes in vanadium flow batteries. This study presents a novel approach to describe the morphological, microstructural, and chemical changes that occur during the activation process and emphasizes the importance of structural defects in surface chemistry.
