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.

Automated summary

In this study, a solid-state electrolyte was developed to overcome the severe dendrites formation and side reactions of zinc metal anodes in aqueous zinc ion batteries. By improving the interface kinetics and ion transferability, the researchers successfully achieved controllable deposition of zinc onto dendrite-free zinc anodes, leading to ultra-stable zinc deposition/stripping behaviors with a lifespan over 1,000 hours. The results demonstrate that the developed hydrogel electrolyte is a promising approach for aqueous zinc ion batteries under various conditions.