Research On Zinc Ion Battery Electrolyte Based On Deep Eutectic Solven

Zinc-ion batteries have the advantages of high energy density,good safety,and low cost,which have become the most promising secondary batteries.However,the problems such as poor stability of electrolytes,serious dendrite growth,and formation of ZnO passivated films seriously hinder their industrial application.Therefore,in this paper,a low eutectic solvent with excellent electrical and electrochemical properties was used as the electrolyte to study the influence of zinc salts（ZnSO₄,ZnCl₂,Zn（CF₃SO₃）₂）on its electrochemical performance and battery performance,in order to develop zinc ion battery electrolyte with excellent electrochemical performance.Specific research contents are as follows:（1）The effect of zinc salt on the electrochemical and electrodeposition behavior of zinc in ChCl-urea DES was studied.The results show that the reduction of Zn²⁺is a quasi-reversible process in all DES electrolytes,but the effect of zinc salts on the electrochemical behavior of zinc is significant.The effect of zinc anion and Zn²⁺to form a complex is as follows:chloride ion>sulfate>trifluoromethyl sulfonate.In addition,zinc salt also has an obvious influence on the morphology and crystal orientation of zinc sediments.Among them,the electrolyte formed by Zn（CF₃SO₃）₂ or ZnSO₄ dissolved in ChCl-urea DES is easy to obtain uniform,smooth,and dendrite-free zinc coating,which is a very ideal zinc ion battery electrolyte.（2）Three zinc salts（ZnSO₄,ZnCl₂,Zn（CF₃SO₃）₂）were added to ChCl-urea as electrolytes for the zinc ion battery cycle performance test.Test results show that in ChCl-urea-ZnSO₄ DES as battery electrolyte Zn||Znhalf-cell performance than other two kinds of electrolytes as battery electrolyte performance is good.（3）The effect of water content on the electrochemical performance of the ChCl-urea-ZnSO₄ DES system was studied.It was found that with the increase in water content,the diffusion rate of zinc ions increased,and the zinc coating gradually became smooth and uniform.When the water content was more than 10%,the zinc deposition quality began to deteriorate,indicating that the electrolyte performance was the best when the water content was 10%.And different water content ChCl-urea-ZnSO₄ DES solution assembled into Zn||Znhalf-cell test.The results also show that when the water content is10%,the battery cycle performance is the best.