Stabilizing a Zn Anode by an Ionic Amphiphilic Copolymer Electrolyte Additive for Long-Life Aqueous Zn-Ion Batteries

The rampant growth of zinc dendrites and severe uncontrollable reactions have largely limited the industrialization of aqueous Zn-ion batteries. Electrolyte additive engineering was found to be a facile yet effective strategy in addressing these issues; however, traditional organic small molecule additives raise additional safety and health risks and thus compromise the intrinsic advantage of aqueous batteries. In this study, we report a polyacrylonitrile-co-poly(2-acrylamido-2-methylpropanesulfonic acid) (PAN-co-PAMPS) copolymer with ionic and hydrophilicity PAMPS and non-ionic PAN, which acts as an electrolyte additive to regulate the Zn deposition in aqueous Zn-ion batteries. The hydrophilicity of PAMPS is designed to meet water solubility. Moreover, ionic PAMPS reacts with a Zn anode surface, chemically peels the surface, leaves a pre-polished anode surface, and removes heterogeneity and impurity of the metal surface. All these effects are beneficial for homogeneous zinc ion deposition and long-life battery. The PAN segments act as a water-shielding layer on a Zn anode to prevent its direct contact with H2O. Consequently, the Zn|Zn symmetric cells with additive-containing electrolytes have a much longer life than those without additives (up to eight times) at a current density of 1 mA cm−2 and a capacity of 1 mA h cm−2. The assembled Zn|Cu cells and the Zn|V2O5 full batteries also display prominent electrochemical reversibility. The reactively acidic amphiphilic polymer provides not only an alternative strategy for the design of multi-functional electrolyte additives, but also constitutes an easy-to-operate way for advancing commercialization of aqueous zinc-storage devices.