“Cyano group bridge”-based enabling high zinc-ion transference number and cycling stability of aqueous zinc-ion batteries

Abstract

To reduce zinc dendrites and side reactions, improving the cycling performance of aqueous zinc-ion batteries (AZIBs), we designed an acrylamide–acrylonitrile copolymer by introducing a small quantity of acrylonitrile that has strong coordination with Zn²⁺ into the hydrophilic acrylamide. Due to the association of cyano groups between macromolecular clews, a “cyano bridge” can be constructed, which provides a fast transference pathway for Zn²⁺, significantly increasing the transference number of Zn²⁺ and improving the cycling stability of AZIBs. The copolymer can regulate the solvation structure of Zn²⁺ and adsorb on the Zn anode surface to form a dynamic protective layer. When the acrylonitrile content is 5%, at a contact concentration of 0.10 wt%, the Zn–Zn symmetric cell using trace copolymer can stably cycle for 1840 hours at a current density of 5 mA cm⁻². The Zn–Cu asymmetric cell has an average coulombic efficiency of 99.23% after 500 cycles. In practical application, the Zn–NVO full battery retains a high capacity retention of 95.45% after 4100 cycles and exhibits good rate performance. This work provides a new approach for the development of economical high-performance aqueous metal-ion batteries.