Zinc Acetate Electrolyte Regulation And Performance Of Zinc-ion Batteries

Zinc-ion batteries（ZIBs）have shown great potential as a new type of secondary battery because of the advantages of high theoretical capacity,low redox potential,and good safety.However,some problems such as dendrites,corrosion,hydrogen evolution,and deformation are suffered by Zn anodes,which can cause battery short-circuits and severely limit the cycling stability of ZIBs.Therefore,improving the anode/electrolyte interface（AEI）is of great significance to solve the above problems.In this work,from the perspective of electrolyte regulation,the zinc acetate electrolytes were modified by adding tea polyphenol additives or constructing gel electrolyte with polymer,so as to improve the deposition behavior of zinc anode and improve the overall performance of zinc ion battery.The main research contents are as follows:（1）A trace amount of tea polyphenols（TP）were introduced into the zinc acetate electrolyte as an additive to protect the zinc anode from corrosion and promote the uniform deposition of Zn²⁺,thereby realizing a dendrite-free zinc anode.IR,Raman,NMR,and the related means were used to reveal the influence of TP molecules on zinc acetate electrolyte.In situ synchrotron radiation X-ray imaging technique was used to reveal the active role of TP molecules in the uniform deposition of zinc.The TP molecules induce the formation of a stable AEI,which effectively suppresses hydrogen evolution and related side reactions,and improves the cycling coulombic efficiency of the battery.The Zn||Zn symmetric battery using the hybrid electrolyte can continuously cycle for more than 720 hours at 0.5 m A cm^-2 and 0.5 m Ah cm^-2.The Zn/Na₃V₂（PO₄）₃ assembled using this electrolyte stably cycle for more than 300 times at a current density of0.2 C with a capacity retention rate of 78%.（2）Using polyvinyl alcohol（PVA）and Zn（CH₃COO）₂（Zn（Ac）₂）as raw materials,a hybrid gel electrolyte with three-dimensional network structure was prepared by a freezing/thawing method.The effects of PVA content and Zn（Ac）₂ concentration on the structure and stability of gel electrolyte were investigated by water absorption performance test,FT-IR,Raman,electrochemical test,and scanning electron microscope.In situ synchrotron radiation X-ray imaging was carried out to elucidate the positive effects of gel electrolyte in enhancing corrosion resistance and inhibiting dendrite growth.When the mixed gel electrolyte was preprared with the optimized condition of 30 wt.%PVA and 1 mol L^-1 Zn（Ac）₂,the electrolyte absorption capacity and ionic conductivity of this mixed gel electrolyte can increase to 233.3%and 5.9 m S cm^-1,respectively.The Zn||Zn symmetric battery assembled with the gel electrolyte can achieve a cycle life of 2200 hours at a current density of 0.25 m A cm^-2.The assembled Zn/Na₃V₂（PO₄）₃ flexible battery can survive 200 cycles at a current density of 0.2 C and has a specific capacity of 107 m Ah g^-1with a capacity retention rate of 73%.In addition,the flexible ZIBs still exhibit high stability after 100 cycles under the conditions such as bending and stretching.This paper includes 46 figures,6 tables and 157 references.