Side Reactions on Zn Anode: What We Know and How We Deal with Them

Aqueous Zn-ion batteries (AZIBs) have been widely regarded as promising alternations to Li-ion batteries (LIBs) owning to their intrinsic safety and cost-effectiveness. Nonetheless, spontaneous side reactions on Zn anode dominated platelet packing mode of Zn plating/stripping, thus undermining the reversibility of Zn anode. To encompass the future development of AZIBs, the undesirable side reactions on Zn anode need to be fully unveiled to enable intrinsic Zn plating/stripping processes. This review offers innovative and comprehensive approaches on the side reactions of Zn anode that haven't been reported. It commences with the profound understanding about the Zn redox chemistry with side reactions involved. Subsequently, the main initiators of side reactions are discussed, and the mainstream strategies in previous reports to decouple main/side reactions are deeply collected and analyzed from the angle of thermodynamics and kinetics on the strength of different mechanisms, with the summary of cutting-edge research breakthroughs. Additionally, advanced characterization technologies are expounded, equipping readers with measures to intuitively detect side reactions. Finally, current challenges relating to side reactions are presented, accompanied by proposed feasible solutions to inspire readers for the development of future AZIBs.