In the "post-lithium ion" battery system, the application value of the aqueous zinc battery is large, and it has received new attention in recent years. A variety of cathode materials have been reported to be compatible with zinc anodes in order to produce breakthroughs in performance. Unlike traditional inorganic cathode materials, the weak intermolecular interactions of the main body of organic materials are more suitable for the storage of multivalent ions, and the highly adjustable organic structure gives it a new ion reaction mechanism. However, the current aqueous zinc electrolytes still have great shortcomings. For example, hydrated [Zn(OH2)6]2+ has high ion activity, which can cause serious side reactions and uneven zinc deposition, and the polarity of discharge products of organic electrodes is relatively high. High, easily dissolved by free water, causing capacity attenuation.
Recently, Cui Guanglei, associate researcher Zhao Jingwen, and associate researcher Zhao Jingwen of the Qingdao Institute of Bioenergy and Process Research, Chinese Academy of Sciences, and Zhang Qichun, a professor at Nanyang Technological University, used a simple, low-cost formulation of hydrated zinc salt plus neutral ligands to propose a method based on succinonitrile ( SN) and zinc perchlorate hexahydrate Zn(ClO4)2·6H2O hydrated molten salt zinc-based electrolyte, which effectively solves the problem of side reactions and irreversible dissolution of zinc negative electrode and organic positive electrode in aqueous electrolyte. Electrochemical tests have found that this hydrated molten salt zinc-based electrolyte effectively suppresses the dendrites and side reactions of the metal zinc anode, and achieves the long-term cycle stability of the zinc anode. Spectral characterization and theoretical calculations revealed that succinonitrile destroyed the [Zn(OH2)6]2+ solvation structure and participated in the solvation of zinc ions. In addition, the water molecules replaced by succinonitrile are still bound by the solvated layer of zinc ions and the unique eutectic structure network of the electrolyte, and exist in a "bound" state similar to bound water. When a sulfur-containing quinone polymer poly(2,3-dithio-1,4-p-benzoquinone) (PDB) is used as the positive electrode of a zinc ion battery, the hydrated molten salt effectively reduces the organic positive electrode Dissolve. Under the condition of 0.3C, the battery was cycled 3600 times, and the capacity retention rate was 85.4%. In addition, when the temperature is successively lowered to -10℃ and -20℃, the battery still shows excellent cycle stability and can output capacities of about 70 mAh g-1 and 40mAh g-1, indicating that this hydrated molten salt electrolyte is promising Used in low temperature environment. This research provides new ideas for the development of new aqueous electrolytes and the development of zinc-organic batteries.
The relevant results were published in Joule. The first authors of the paper were Yang Wuhai from Qingdao University of Science and Technology and Du Xiaofan from Qingdao Energy Institute. The research was supported by the National Natural Science Foundation of China, the Youth Promotion Association of the Chinese Academy of Sciences, and the Dalian Chemical Institute-Qingdao Energy Institute Fusion Fund.
Schematic comparison of the solvation structure of hydrated molten salt electrolyte and traditional aqueous electrolyte
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