Abstract:Aqueous zinc-ion batteries (AZIBs) have emerged as a promising new generation of electrochemical energy storage devices due to their high specific capacity, excellent safety, and economic advantages. However, the ZnSO4 electrolyte system is plagued by issues such as a narrow voltage window, poor ionic conductivity, high water activity leading to zinc anode corrosion and dendrite growth, which significantly hinders the performance improvement and industrial application of AZIBs. Many researchers have attempted to modify the ZnSO4 electrolyte by introducing additives. The introduction of organic additives (such as chitosan, D-xylose, tetrahydrofurfuryl alcohol, etc.) into the electrolyte can effectively enhance the battery s cycle life and ionic conductivity through mechanisms such as forming a dynamic interface protective layer, reconfiguring the solvation structure, and suppressing side reactions. Some modified batteries can achieve thousands of hours of cycling. The addition of inorganic additives (such as vanadium sulfate, potassium tripolyphosphate, europium chloride, etc.) can achieve uniform zinc deposition and electrode protection by leveraging the ion synergy effect, inducing crystal orientation growth, and in-situ forming a dense SEI layer, significantly improving the battery s capacity and rate performance. The introduction of ionic additives (such as ammonium hexadecyltrimethyl sulfate, ammonium bicarbonate, ammonium salicylate, etc.) can effectively inhibit zinc dendrite growth and hydrogen evolution reactions, and broaden the electrochemical window of the electrolyte through electrostatic shielding, pH buffering, and optimizing the interface charge distribution. The addition of polymer additives (such as polyacrylic acid, polyethyleneimine, carbonized polymers, etc.) can optimize the electrode/electrolyte interface environment through selective adsorption, regulating the interface electric field, and reducing the desolvation barrier, significantly enhancing the battery s cycle stability and reversibility. Although the introduction of additives in the electrolyte has targeted solutions to some key problems of the ZnSO4 electrolyte, there are still issues such as the unclear mechanism of action of various additives and the difficulty of a single additive to simultaneously address all defects of the electrolyte. Moreover, the long-term cycle stability and scalability of AZIBs still need further verification. In the future, in-depth research is needed in areas such as developing multifunctional additives (zinc deposition regulation, dual-interface passivation, solvation structure reconstruction) and composite additives (multi-component hybrid synergy, composition/concentration optimization) to enhance the performance of AZIBs and promote their industrial application.
