Recently, Li Xianfeng, Research Fellow of the Department of Energy Storage Technology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhang Huamin’s research team has made new progress in the research of high energy density, long-lived zinc-iodine flow batteries. Research results as 'Very Important Paper' online Published on Angew. Chem. Int. Ed.
Large-scale energy storage technology is a key core technology for achieving the universal application of renewable energy. Because of its high safety, large-scale energy storage, high efficiency, and long life, flow batteries have good applications in large-scale energy storage applications. Prospects: Zinc-iodine flow batteries have good electrochemical activity, high electrolyte solubility, high energy density (theoretical energy density up to 250.59Wh/L), and have good research and application prospects. However, current zinc-iodine flow batteries There is a problem of short cycle life and low power density.
To solve the above problems, the research team proposed replacing the expensive perfluorinated sulfonic acid ion exchange membrane with a cheap polyolefin porous membrane (15 US dollars/m2), which greatly reduced the cost of the battery. In addition, the system uses a mixed solution of KI and ZnBr2. As the positive and negative electrode electrolyte of the battery, the conductivity and stability of the electrolyte in the neutral environment are greatly improved. Since the porous structure of the polyolefin porous film exhibits excellent ion conductivity in a neutral environment, the working current density of the battery is high. Increased amplitude. The experimental results show that the energy efficiency of a single cell reaches 82% at 80mA/cm2, which is 8 times higher than that of the previously reported zinc iodide system, and the energy density reaches 80Wh/L. Under the 180mA/cm2 operating condition, the battery The energy efficiency of more than 70% shows good power characteristics. More importantly, the porous electrolyte structure I3-, which is filled with an oxidation state, reacts with zinc dendrite to solve the problem of the battery due to zinc dendrite. The problem of poor cycle life. Even if the battery is short-circuited due to zinc dendrite, the battery performance can also be self-healing through the dissolution of I3- on the zinc dendrites in the film pores. The system cell is at 80m. More than 1000 cycles of continuous operation under A/cm2, no significant degradation in performance, showed a good stability. To further confirm the practicality of the system, the research team successfully integrated kW class reactor, the stack at 80mA/cm2 With more than 300 cycles of stable operation, the energy efficiency is stable at 80%, showing excellent reliability. The battery is still in the initial stage of research and needs to further improve its reliability under high current density, and promote its practical and industrialization. .
The above work provides a good reference for the development of a new generation of high performance liquid flow battery systems, and also provides new ideas for the development of other zinc-based flow batteries.
