Liquid flow batteries are considered one of the most promising energy storage technologies at present due to their excellent safety, high energy storage capacity, long cycle life, and lower cost. At present, in order to solve the problem of wind and solar power curtailment caused by excess wind and solar power generation, one effective way to solve this problem is to install corresponding energy storage stations in new energy technology power stations. Among them, liquid flow batteries can adapt well to the discontinuous and intermittent characteristics of solar and wind power generation. In the field of flow battery technology, all vanadium flow battery technology has developed the most maturely with continuous technological innovation in recent years. Currently, all vanadium flow battery energy storage stations have also entered the stage of large-scale commercial operation. Governments across the country have also introduced relevant industrial layouts to promote the continuous development of all vanadium flow battery technology energy storage.

The concept of all vanadium flow battery was first proposed in the 1980s by the Maria Skyllas Kazacos team at the University of New South Wales in Australia [1]. They first proposed using VO2+/VO2+as the positive electrode active substance and V2+/V3+as the negative electrode active substance of all vanadium flow battery. Through the oxidation-reduction reaction of positive and negative electrode active substances, electricity is generated, achieving the conversion of chemical energy. The schematic diagram of the structure of all vanadium flow battery is shown in the following figure.

picture
Schematic diagram of all vanadium flow battery structure [2]

In all vanadium flow batteries, electrode materials located on both sides of the ion exchange membrane are one of the core components, and the electrode surface is the site where redox reactions occur in all vanadium flow batteries. The electrodes of all vanadium batteries are different from other battery systems in that their electrode materials do not directly participate in the reaction as reactants, but only provide a place for electron exchange and ion conversion. Therefore, as electrodes, their general requirements often include the following aspects:

(1) Excellent conductivity: The excellent electrical performance corresponding to high conductivity has a significant impact on the overall operational efficiency and power output of the battery system. In all vanadium flow batteries, the resistance of the electrode materials used should be as small as possible to reduce their degree of Ohmic polarization during the reaction process and improve the overall efficiency of the battery system;

(2) Outstanding mechanical performance: High mechanical strength is conducive to achieving good catalyst loading and ensuring the structural stability of all vanadium flow batteries during operation, in order to avoid the collapse of the internal structure of the battery, which can lead to the collapse of the battery system;

(3) Having good structural characteristics: A stable and good electrode material structure will facilitate effective contact between the reactive substance and the catalyst loaded on the electrode, promoting efficient redox reactions in the electrolyte;

(4) Cost advantage and environmentally friendly characteristics: On the basis of meeting the requirements of conductivity, mechanical performance, and structural characteristics, electrode costs should be minimized as much as possible to minimize the impact on the environment, in order to achieve the widespread application of all vanadium flow batteries.

At present, research on vanadium battery electrode materials at home and abroad mainly focuses on metal electrodes and carbon electrodes [3]. The widely studied materials in metal electrodes include gold, lead, titanium, titanium based platinum, and titanium based iridium oxide. However, so far, the electrochemical performance of batteries demonstrated by gold, lead, and titanium is relatively poor. Although titanium based platinum and titanium based iridium oxide can better meet the requirements of the first three points for electrode materials, their cost is high and it is difficult to achieve large-scale and widespread application. Therefore, more attention has been paid to carbon electrode materials with significant cost advantages.

Carbon electrode materials mainly include carbon fiber materials such as glassy carbon, carbon paper, graphite felt, and carbon felt. Among them, graphite felt and carbon felt are used as the main electrode materials for vanadium flow batteries due to their relatively low cost, good stability, outstanding conductivity, and high specific surface area. At present, the main commercial preparation method is to use polyacrylonitrile based (PAN) precursor as raw material, obtain high carbon content inorganic carbon fibers (carbon content greater than 92%) through a series of heat treatment steps, and then make electrodes. This process is also known as the carbonization and graphitization process in the production of graphite felt electrodes. The mechanism of the oxidation-reduction reaction between graphite felt electrodes and vanadium ions is shown in the figure [5]. At present, the main production companies of PAN based carbon fiber in foreign countries include Japan's Toray, Tobon, Mitsubishi Rayon Company, the American companies Hockley and Amok, and Germany's SGL Company. However, at present, there are still certain limitations in the electrochemical activity and poor hydrophilicity of graphite felt electrodes, and the modification of their electrodes is constantly being promoted and developed to better improve the operational efficiency of vanadium batteries.

picture
picture
The mechanism of the redox reaction between graphite felt electrodes and vanadium ions is shown in the figure [5]

At present, according to the reported relevant patents, it is generally necessary to further process the produced carbon electrodes to obtain carbon electrode materials with high electrochemical activity, few side reactions, and stable cycling performance. This article reviews and analyzes the main patents applied for in the past five years regarding the preparation of electrodes for all vanadium flow batteries.

Professor Zhang Huamin and others from Dalian Institute of Physics and Chemistry have reported on the preparation and optimization of vanadium flow battery electrode materials in their patents [7]. The method and idea is to load catalysts onto activated carbon matrix materials through relevant processes to achieve efficient electrode preparation. The raw materials for its carbon electrode are carbon paper, carbon cloth, or carbon felt, and then carbon supported oxides (tungsten oxide, molybdenum oxide, ruthenium oxide) are impregnated or coated on the activated electrode. And carbon nanotubes, carbon nanofibers, or carbon spherical particles are selected as carbon carriers for electrocatalysts to achieve better electrode performance. The assembled flow battery was tested for charge and discharge at a current density of 40mA/cm2, and the current efficiency, voltage efficiency, and energy efficiency of the all vanadium flow energy storage battery were 90.7%, 91.7%, and 83.5%, respectively.

Professor Liu Suqin and others from Central South University proposed a method for preparing negative electrodes for all vanadium flow batteries in their patent, in order to obtain negative electrodes for all vanadium flow batteries with high electrochemical activity, good kinetic reversibility, and high stability. The preparation method can be summarized as the following steps [6]:

(1) Activation of carbon electrode substrate: The activation method involves soaking the carbon electrode substrate in high concentration sulfuric acid, heating it (at 70-90 ℃), followed by washing and drying steps to complete the activation and obtain the activated carbon electrode substrate;

(2) Catalyst ultrasonic loading and carbon electrode substrate: The catalyst solution is prepared by a complex of organic solvents (N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, ethanol or acetone, etc.) with metals (nickel, bismuth, tungsten, etc.) and ethylenediaminetetraacetic acid. Subsequently, the activated carbon substrate is added to the catalyst solution for ultrasonic loading and drying to obtain a negative electrode for all vanadium flow batteries with high electrochemical activity, good kinetic reversibility, and high stability. After 300 cycles of charge and discharge, the energy efficiency of the battery assembled with the loaded catalyst electrode decreased from the initial 71.4% to 70.9%, a decrease of 0.7%; The energy efficiency of the battery assembled with unmodified electrodes decreased from the initial 64.1% to 58.8%, a decrease of 8.3%. The stability of the modified electrodes was greatly improved.

Li Fan and others from the University of Electronic Science and Technology of China proposed a method for modifying graphite felt electrodes for all vanadium flow batteries in their patent [8]. The steps reported can be summarized as follows: first, immerse the graphite felt in an acid composed of sulfuric acid and/or nitric acid for ultrasonic treatment to increase its hydrophilicity and activate it. Then, prepare an aniline solution and use cyclic voltammetry to electropolymerize polyaniline on the surface of the graphite felt. Finally, heat and carbonize the graphite felt in a tube furnace under a protective atmosphere, and finally prepare a modified electrode for all vanadium flow batteries. The charge and discharge current density of the modified graphite felt electrode after assembly in an all vanadium flow battery is 80mA/cm2. The voltage efficiency of the graphite felt electrode in the all vanadium flow battery is 83.8%, and the energy efficiency is 81.5%.

Liu Tao et al. from Dalian Institute of Physics and Chemistry reported in their patent a highly active electrode for all vanadium flow batteries made from a carbon based material modified on the surface of an aluminum oxide electrocatalyst [9]. Its all vanadium flow battery uses α - Al2O3 modified carbon felt as the electrode. When operating at a current density of 40mA/cm2, the voltage efficiency and energy efficiency are 93.9% and 86.2%, respectively; When the current density is increased to 120mA/cm2, the voltage efficiency and energy efficiency still remain at 84.7% and 80.8%. In addition, in another patent, Liu Tao et al. also reported the preparation of an electrode material for all vanadium flow batteries [12]. The electrode material prepared was a carbon fiber felt containing polyacrylonitrile based carbon fibers and asphalt based carbon fibers, which can effectively reduce electrode costs. And using the prepared activated carbon felt as the electrode, the voltage efficiency and energy efficiency of the all vanadium flow battery were 91.4% and 86.1%, respectively, at a current density of 80mA/cm2; When the current density is increased to 120mA/cm2, the voltage efficiency and energy efficiency remain at 85.8% and 81.8%, respectively. In another patent, Liu Tao et al. also reported a method for preparing positive electrode materials for all vanadium flow batteries [19]. The reported positive electrode material is a mixed carbon fiber felt composed of porous polyacrylonitrile based carbon fibers and porous asphalt based carbon fibers, which is prepared by sequentially carbonization, activation, and graphitization treatment. The positive electrode was loaded into an all vanadium flow battery for charge discharge testing. At a current density of 80mA/cm2, the Coulombic efficiency, voltage efficiency, and energy efficiency were 95.1%, 89.8%, and 85.4%, respectively; When the current density is increased to 120mA/cm2, the Coulombic efficiency, voltage efficiency, and energy efficiency remain at 96.3%, 84.2%, and 81.1%, indicating a significant improvement in battery performance. In addition, Liu Tao et al. also developed a paper-based all vanadium flow battery electrode. It is prepared by acid washing, alkali washing, high-temperature heat treatment, and activation treatment of industrial filter paper. As it replaces polyacrylonitrile based carbon fiber felt, the cost of its electrode material can be greatly reduced [23].

Huang Yi from Suzhou Shuguangxiu New Energy Technology Co., Ltd. reported in his patent a high-performance electrode preparation process for all vanadium flow batteries [10]. The process steps can be summarized as follows: first, disinfect and clean the carbon felt raw material, then place it in a sodium carbonate solution for ultrasonic vibration, pulse treat the mixed solution, and then filter and separate to obtain a precipitate. The obtained precipitate is wet ball milled, and the ball abrasive is heated to obtain electrode material. After annealing and cooling, carbon nanotube suspension is sprayed on the surface and dried in an oven to obtain the final electrode. The electrode produced by this process has good corrosion resistance and strong oxidation resistance, and is not prone to passivation. The number of charge and discharge cycles in all vanadium flow batteries can reach more than 10000. This process has also been similarly reported in another patent [11], which focuses on using carbon felt as raw material and micro etching the surface of carbon felt through high-frequency voltage pulses to achieve high-performance electrode preparation, but only corresponding reports have been made on the cycle life.

Wu Xiongwei of Hunan Agricultural University and others reported in their patent a preparation method of electrode material for all vanadium liquid flow battery constructed by boron doped aerogel [12]. The electrode material is made of linear polymer (polyvinyl alcohol, polyethylene oxide, polyvinylidene fluoride, polyvinyl butyral and polyvinyl pyrrolidone) as the skeleton, boric acid or borate as the crosslinking agent, and boron doped aerogel network is generated in situ in carbon based materials (carbon felt, carbon cloth, carbon paper and graphite felt). By conducting charge discharge tests on the all vanadium flow battery assembled with its electrodes, the voltage efficiency and energy efficiency of the all vanadium flow battery were 73.3% and 71.2% at a current density of 200mA/cm2.

Chen Fuyu and others from Shenyang Agricultural University also reported in their patent a method for preparing electrode materials for all vanadium flow batteries [13]. The preparation method can be summarized as follows: using alkaline lignin as raw material, using the phenolic hydroxyl active functional group contained in its structure, under the action of catalyst, hydroxymethylated alkaline lignin partially replaces resorcinol and formaldehyde to synthesize organic gel, using this gel as precursor, prepare the precursor spinning solution required for the experiment, prepare the fiber precursor electrode material by electrospinning, use vacuum/atmosphere furnace to pre oxidize the electrode precursor, carbonize in inert atmosphere, and obtain carbon fiber electrode material. However, there is not much specific mention in the patent regarding the performance of the prepared electrode.

Ren Zhongshan and others from Qinghai Baineng Huitong New Energy Technology Co., Ltd. reported in their patent a method for preparing composite end electrodes for all vanadium flow batteries [14]. The composite end electrodes prepared mainly include carbon felt, electrode sheets, insulation board outer frame sheets, and copper electrode sheets. The preparation process can be summarized as: cutting and preparing the end electrode blank component; End electrode blank hot pressing forming; End electrode blank machining; Weld the carbon felt layer to produce a composite end electrode. The patent claims that the composite end electrode can effectively reduce surface contact resistance, thereby improving the voltage efficiency of all vanadium flow batteries, but there is no specific data to support it.

The method for preparing electrode materials for all vanadium flow batteries disclosed by Fan Shunhua of Guangzhou Shangwan Technology Co., Ltd. in its patent is to stir and mix graphene and dopamine in a certain proportion (1:1.5-2.3) to obtain a solution, heat treat the cut graphite felt in an oven for 3 hours, immerse it in the above solution, and add a buffer (citric acid, carbonic acid, barbituric acid or trimethylaminomethane) to adjust the pH value of the solution so that dopamine begins to self polymerize. Then, it is naturally dried and placed in a tube furnace for carbonization under inert gas conditions to obtain the graphite felt electrode material [15]. The electrode preparation method reported by it showed a decrease of over 40% in the body resistance during battery testing after assembly, but its battery performance data has not been reported.

Wei Da and others from Hunan Dewup New Energy Co., Ltd. also proposed a method for preparing composite electrode materials for all vanadium flow batteries in their patents [16]. The composite electrode includes a substrate layer and a covering layer, using a carbon substrate as the substrate layer and covering with phosphorus doped carbon nanotubes to improve the electrochemical activity, conductivity, and specific surface area of the electrode. The current efficiency of the vanadium flow battery assembled with the composite electrode it produces is 96%~98%, the voltage efficiency is 86%~90%, and the energy efficiency is 83%~86%.

Cui Guanglei, from the Chinese Academy of Sciences Qingdao Institute of Bioenergy and Process, and others also reported in their patents a composite electrode for all vanadium redox flow batteries [17]. The electrode includes active materials, auxiliary active additives (graphite oxide, graphene oxide, carbon nanotubes oxide, carbon fibers oxide), and binders. The preparation method can adopt the "direct mixing and rolling" method, which directly forms a slurry by stirring and mixing the active material, auxiliary active additives, and binders in proportion, forms a film by scraping and coating, and then dries, rolls, forms, and cuts to obtain a composite electrode; Alternatively, the "mixed solution suction filtration+roller pressing" method involves thoroughly ultrasonic stirring and mixing the active materials, auxiliary active additives, and binders in proportion in the aqueous solution. The membrane is formed using the suction filtration method, and then dried, roller pressed, formed, and cut to obtain a composite electrode. It was assembled into an all vanadium ion battery for charging and discharging experiments. At a current density of 20mA/cm2, the voltage efficiency of the prepared composite electrode was about 95%.

Tang Hongli and others from Hunan Yinfeng New Energy Co., Ltd. proposed a modification method for carbon felt electrodes used in all vanadium flow batteries [18]. The main steps are: ultrasonic treatment of carbon felt in anhydrous ethanol or acetone, followed by washing and drying, followed by heating nitric acid in a closed container to produce high-temperature and high-pressure nitric acid vapor for gas-phase oxidation treatment of carbon felt, cooling and washing, and then drying to obtain modified carbon felt. The current efficiency of the modified carbon felt at a charge and discharge current density of 100 mA/cm2 exceeds 97%, the voltage efficiency is about 83%, and the energy efficiency is about 82%, all of which have been improved to a certain extent.

Zhang Suojiang, et al. from the Institute of Process Engineering, Chinese Academy of Sciences, put forward a preparation method of cathode material for liquid flow battery in their patent [20]. The main steps of preparing sulfur Koqin black graphene composite materials include: adding Koqin black to water, then adding Na2S2O3 · 5H2O, and finally adding concentrated hydrochloric acid to mix evenly to obtain a mixture; Add graphene oxide suspension to the prepared mixture, mix evenly, solid-liquid separation, wash and dry. The liquid flow battery made from it has a specific capacity of 1210mAh g-1 under static conditions, a discharge specific capacity of 263Wh L-1, and a discharge specific capacity of 251Wh L-1 under intermittent flow conditions.

Zhang Jin and others from Beihang University proposed a modified electrode preparation method for all vanadium flow batteries in their patent [21]. The preparation process can be summarized as follows: using tin chloride, antimony chloride, and isopropanol to prepare a precursor solution, then immersing carbon paper or carbon felt in the solution, using the pull-up method to attach nanoparticles from its relevant solution to the surface of carbon paper or carbon felt fibers, drying, and then calcining the carbon paper in a tubular furnace to complete the preparation of modified electrodes, achieving the attachment of antimony doped tin dioxide nanoparticles to the surface of the substrate material (carbon paper or carbon felt fibers). The all vanadium flow battery assembled with its prepared electrodes was subjected to charge and discharge tests under 90mA/cm2 conditions, with a Coulombic efficiency of 98.5%, a voltage efficiency of 73.3%, and an energy efficiency of 72.2%.

Sun Hong and others from Shenyang Jianzhu University reported a method for preparing high-performance graphite felt electrodes for all vanadium flow batteries [22]. The preparation method can be summarized as follows: first, wash and dry the polyacrylonitrile graphite felt electrode, then deposit polydopamine layer by layer on the graphite felt electrode through electrochemical deposition, and finally wash and dry the electrode to obtain. It claims to improve the overall performance of all vanadium flow batteries, but no relevant comparative data is listed.

Many companies are also continuously optimizing and improving the production and processing technology of vanadium flow battery electrodes. We have also paid attention to Liaoning Jingu Carbon Materials Co., Ltd. and analyzed its three patents. In 2013, Liu Dongying et al. published a production method for graphite felt for vanadium batteries in their patent [24]. They proposed a method of connecting a continuous sintering furnace and a continuous activation furnace in series to achieve the conversion from pre oxidation felt to graphite felt, thereby improving its production efficiency and product quality. The first 2/3 of the sintering furnace achieves a gradual temperature rise from room temperature to 1600 ℃, the last 1/3 achieves a gradual temperature drop, while the first 72% of the activation furnace achieves a temperature rise from room temperature to 960 ℃, and the last 28% achieves a gradual temperature drop. In 2018, it once again announced the production method of graphite felt for high-performance vanadium batteries, which is a continuation and improvement of the method proposed in 2013 [25]. Its production still involves connecting a continuous sintering furnace and a continuous activation furnace. During the sintering furnace production process, using a ferrocene catalyst under inert gas protection, carbon nanotubes can be formed on the surface of the carbon felt by reacting with carbon sources such as short chain hydrocarbons and amorphous carbon emitted from the raw material felt, resulting in modified graphite felt. Then, steam or other gases are introduced into the continuous activation furnace to activate the modified graphite felt, resulting in high-performance graphite felt products. The highest sintering temperature range during the production process is improved to 1500-1800 ℃, and the highest activation temperature is adjusted to 800-950 ℃. The voltage efficiency of carbon nanotube modified graphite felt fluctuates between 90.2% and 90.46%, which is better than the voltage efficiency of unmodified graphite felt (85.75% -86.78%). In 2019, Li Bo et al. proposed a production method for modified vanadium battery porous electrode graphite felt [26]. Based on the previous process of pre oxidation felt entering the continuous sintering furnace sintering (low-temperature carbonization zone and high-temperature graphitization zone) and continuous activation furnace activation treatment, catalyst bismuth nitrate powder was uniformly sprinkled before the graphite felt activation treatment, which not only achieved the construction of nanoscale microporous structure on the surface of the oxide felt to increase the specific surface area, but also the surface deposition of bismuth nitrate decomposition products further modified the surface of the carbon felt.

The preparation of carbon electrodes with high electrochemical activity, high battery kinetic reversibility, high wettability, and high stability is undoubtedly one of the key factors for improving the operational efficiency of all vanadium flow batteries. Currently, many studies have made good experimental progress by modifying carbon electrode materials, and the experimental results have also been continuously applied in commercial production. We believe that with the continuous support of national policies, the electrodes used in all vanadium flow batteries will continue to achieve further development and breakthroughs. Moreover, with the carbon based electrodes used in all vanadium flow batteries ensuring efficient operation of the battery, the significant reduction in costs brought to the battery system will contribute to the further development and commercial application of all vanadium flow batteries in the field of electrochemical energy storage.



Main reference materials:

[1] SKYLLAS-KAZACOS M, RYCHCIK M, ROBINS R G, et al. New All Vanadium Redox Flow Cell [J] Journal of the Electrochem Society, 1986, 133 (5): 1057-1058

[2] Jing Xin, Li Xia, Han Wenjia. Research progress on electrodes and proton exchange membranes for all vanadium flow batteries [J]. Polymer Bulletin, 2021 (05): 1-13 DOI:10.14028/j.cnki.1003-3726.2021.05.001.

[3] Zhang Wenze, Wang Yue, Wu Xianwen, Luo Fei, Cheng Gang, He Zhangxing. Research progress on electrode materials for all vanadium flow batteries [J]. Journal of Jishou University (Natural Science Edition), 2016,37 (04): 61-66

[4] Su Xiuli, Yang Linlin, Zhou Yu, Lin Youbin, Yu Shuyuan. Research progress on electrodes of all vanadium flow batteries [J]. Energy Storage Science and Technology, 2019,8 (01): 65-74

[5] Zeng Yan, Lv Zaosheng, Liu Yuchen, Zhou Ying, Liang Feng. Modification of graphite felt electrodes in all vanadium flow batteries [J]. Electroplating and Fine Decoration, 2019, 41 (01): 15-21

[6] Liu Suqin, Liu Bingjun, Yuan Xiugui A negative electrode for all vanadium flow batteries and its preparation method, as well as all vanadium flow batteries [P] Hunan Province: CN108461758B, 2020-12-29

[7] Zhang Huamin, Yao Chuan, Wang Xiaoli An electrode material for all vanadium flow energy storage batteries and its application [P] Liaoning Province: CN102867967B, 2015-08-19

[8] Li Fan, Zhang Shu, Wu Mengqiang, Feng Tingting Graphite felt electrodes and modification methods for all vanadium flow batteries [P] Sichuan Province: CN113054203A, 2021-06-29

[9] Liu Tao, Li Xianfeng, Zhang Huamin An electrode material and its application in all vanadium flow batteries [P] Liaoning Province: CN112952115A, 2021-06-11

[10] Huang Yi An electrode preparation process based on high-performance all vanadium flow batteries [P] Jiangsu: CN108598513A, 2018-09-28

[11] Huang Yi A method for preparing electrodes for all vanadium flow batteries [P] Jiangsu: CN108539212A, 2018-09-14

[12] Liu Tao, Li Xianfeng, Zhang Huamin, Yin Hongtao An electrode material for all vanadium flow batteries and its preparation and application [P] Liaoning Province: CN109841851A, 2019-06-04

[13] Chen Fuyu, Ma Qingbang, Liu Qingyu, Jin Hong A preparation method for electrode materials of all vanadium flow batteries [P] Liaoning Province: CN107039659B, 2019-12-06

[14] Ren Zhongshan, Li Sensen, Jia Dongran, Liu Xuejun, Meng Lin, Lu Ke A composite end electrode for all vanadium flow batteries and its preparation method [P] Qinghai Province: CN110600750A, 2019-12-20

[15] Fan Shunhua A method for preparing electrode materials for all vanadium flow batteries [P] Guangdong Province: CN113809338A, 2021-12-17

[16] Wei Da, Liu Zushe, Liu Jie A composite electrode material for all vanadium flow batteries and its preparation method, as well as all vanadium flow batteries [P] Hunan: CN108172877A, 2018-06-15

[17] Cui Guanglei, Han Pengxian, Yao Jianhua A composite electrode for all vanadium flow batteries and an all vanadium flow battery using this electrode [P] Shandong Province: CN107768686B, 2020-03-24

[18] Tang Hongli, Yin Xingrong, Wu Xuewen, Wu Xiongwei, Liu Jun, Xu Hui, Sun Xiaosheng, Xiang Xiaojuan, Zhang Jie, Peng Li, Hu Yongqing A modification method for carbon felt electrodes used in all vanadium flow batteries [P] Hunan: CN108091888A, 2018-05-29

[19] Liu Tao, Li Xianfeng, Zhang Huamin, Yin Hongtao A positive electrode material for all vanadium flow batteries and its preparation and application [P] Liaoning Province: CN109841850A, 2019-06-04

[20] Zhang Suojiang, Xu Song, Zhang Lan, Zhang Xiangping, Cai Yingjun A positive electrode material for liquid flow batteries and its preparation method [P] Beijing: CN108666582B, January 15, 2021

[21] Zhang Jin, Yang Chunmei, Liu Yiyang, Lu Shanfu, Xiang Yan, Lv Yang A modified electrode and its preparation method for all vanadium flow batteries [P] Beijing: CN107221681A, 2017-09-29

[22] Sun Hong, Li Qiang, Bai Juyu A high-performance graphite felt electrode and its preparation method for all vanadium flow batteries [P] Liaoning Province: CN110197903A, 2019-09-03

[23] Liu Tao, Li Xianfeng, Zhang Huamin, Yin Hongtao A paper-based all vanadium flow battery electrode material and its preparation and application [P] Liaoning Province: CN111261881A, 2020-06-09

[24] Liu Dongying, Li Bo, Zhang Ronglu, He Lixin, Yue Bin, Sun Zhentao The production method of graphite felt for vanadium batteries [P] Liaoning Province: CN103151537B, 2014-11-26

[25] Liu Dongying, Li Bo, Xing Yangyang, Zhang Ronglu, Li Xiangdong, Dong Yue, Li Xiaosong The production method of graphite felt for high-performance vanadium batteries [P] Liaoning: CN108598500A, 2018-09-28

[26] Li Bo, Liu Dongying, Xing Yangyang, Dong Yue, Sun Qi, Li Peng A production method of modified vanadium battery porous electrode graphite felt [P] Liaoning Province: CN110518260A, 2019-11-29



More articles

Comparative analysis of safety risks between liquid flow batteries and lithium-ion batteries

Analysis of the trillion dollar long-term energy storage market and technology

Technical analysis and case study of mixed energy storage stations for all vanadium flow batteries and lithium batteries