Hydrogel electrolyte membrane with regulated pore effect to stabilize zinc anode in aqueous zinc-ion batteries

The unregulated dendrite growth and deleterious derivative reactions at Zn anodes lie in the path of research and industrialization of aqueous Zn-ion batteries (AZBs). The pore of the separator is a natural sieve for ion diffusion, but the high energy barrier for transmembrane transport can cause the “bridging” effect of ion congestion at the pore entrance, and induce the incubation of dendrites instead. In this work, a continuous, stable and fast ion transport channel is constructed by in-situ guided cross-linking of zinc alginate (ZA) hydrogels through the porous membrane to conquer the negative pore effect. The homogeneity and continuity of the channel structure, as well as the high ionic conductivity and zincophilicity of the ZA, can homogenize the electric field and reduce the energy barrier for ion transport. In battery systems, the physical ion shunting effect of a homogeneous pore structure, combined with the chemical/electrochemical effects of ZA guiding the diffusion of Zn2+ and binding free water, combat zinc dendrites and interfacial side reactions. The novel electrolyte membrane enables a highly reversible Zn plating/stripping to stabilize the Zn anode. This work provides illuminating insights into the regulation and application of pore effects in porous electrolyte membranes in metal-based batteries.