Dalian Institute of Physics and Chemistry has developed a zinc battery that can 'self-recover' even after a short circuit

Lithium Grid News: Recently, the research team led by Li Xianfeng and Zhang Huamin, researchers of the Energy Storage Technology Research Department of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, has made new progress in the research of high-energy density and long-life zinc-iodine flow batteries. The research results were published online as 'Very Important Paper' in 'Angew. Chem. Int. Ed.'.

　　 Large-scale energy storage technology is the key core technology to realize the popularization and application of renewable energy. Flow battery has high safety, large-scale energy storage, high efficiency and long life. It has good application prospects in the field of large-scale energy storage. The zinc-iodine flow battery has good research and application prospects due to its good electrochemical activity, high electrolyte solubility, and high energy density (theoretical energy density can reach 250.59Wh/L). However, the current zinc-iodine flow battery has the problems of short cycle life and low power density.

　　 In order to solve the above problems, the research team proposed to replace the expensive perfluorosulfonic acid ion exchange membrane with a cheap polyolefin porous membrane (15 US dollars/m2), which greatly reduces Battery cost. In addition, the system uses a mixed solution of KI and ZnBr2 as the battery's positive and negative electrolytes, which greatly improves the conductivity and stability of the electrolyte in a neutral environment. Since the porous structure of the polyolefin porous membrane exhibits excellent ion conductivity in a neutral environment, the operating current density of the battery is greatly improved.

The experimental results show that operating at 80mA/cm2, the single cell energy efficiency reaches 82%, which is 8 times higher than the previously reported zinc-iodine system, and the energy density reaches 80Wh/ L; Under the operating condition of 180mA/cm2, the energy efficiency of the battery exceeds 70%, showing good power characteristics. More importantly, the oxidized electrolyte I3- filled in the polyolefin porous structure can react with zinc dendrites, which solves the problem of poor battery cycle life caused by zinc dendrites. Even if the battery is short-circuited due to zinc dendrites, the battery performance can be self-healing through the dissolution of zinc dendrites by I3- in the membrane pores. The single cell of this system runs continuously for more than 1000 cycles under 80mA/cm2, and its performance has no obvious degradation, showing good stability. In order to further confirm the practicability of the system, the research team successfully integrated a kW-class stack, which runs stably for more than 300 cycles at 80mA/cm2, and the energy efficiency is stable at 80%, showing very good reliability. The battery is still in the initial stage of research, and it is necessary 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 flow battery new system, and also provides new ideas for the research and development of other zinc-based flow batteries .