High-adhesion anionic copolymer as solid-state electrolyte for dendrite-free Zn-ion battery

To conquer severe dendrites formation and side reactions of zinc metal anodes, which are serious obstacles for the practical applications of aqueous zinc ion battery (ZIB), herein, we develop a sodium allysulfonate (SAS) and acrylamide (AM) copolymer by radical polymerization process (crosslinking of C=C) as solid-state electrolyte. The interface kinetics is improved remarkably due to the high adhesion and excellent ion transferability of AM-SAS (AS) copolymers. Especially the sulfonic acid group in the hydrogel electrolyte can enhance the internal ionic conductivity effectively benefiting from its high affinity to Zn²⁺. Also, polymer chains realize re-regulation to Zn²⁺ flow in atomic-scale, thus leading to controllable deposition of Zn onto the dendrite-free Zn anodes. Consequently, the AS-1.5 electrolyte achieves ultra-stable Zn deposition/stripping behaviors with the lifespan over 1,000 h via the suppression of side-reactions and paralleled Zn deposition. High performances of Zn/Mn-doped V₂O₅ (MnVO) (over 500 cycles) and Zn/diquinoxalino [2,3-a:2',3'-c] phenazine (HATN) (over 2,500 cycles) full cells demonstrate that the AS hydrogel electrolyte is a common approach for ZIBs under various conditions. This molecular regulation engineering opens a novel route for hydrogel electrolyte fabrication, where sulfonic groups perform as media of Zn²⁺ transfer. Therefore, high bulk ionic conductivity as well as excellent interface ion diffusion ability is obtained.