Enabling high-performance Zn–I2 batteries with a solvation-regulating, ion-selective, and flexible sulfonic acid-water reducer gel electrolyte

RWTH Publications (RWTH Aachen)

Abstract

Rechargeable aqueous Zn-I 2 batteries face challenges from zinc anode degradation (dendrites, corrosion) and polyiodide (I 3 -/I 5 -) shuttling at the cathode, limiting cycle life.To address these issues simultaneously, a novel ion-selective, solvationregulating, and flexible sulfonic acid-based water reducer gel electrolyte (polyacrylamide (PAM)polynaphthalene sulphonate (FDN)-carboxylated chitosan (CCS)/zinc sulfate (ZSO)) is designed in this work.This electrolyte features a three-dimensional (3D) porous structure and abundant polar groups enabling efficient Zn 2+ transport and solvation structure regulation, promoting uniform zinc deposition and suppressing water-related side reactions (e.g., hydrogen evolution) at the anode.Crucially, the strongly negatively charged sulfonic acid groups impart exceptional ion selectivity: They electrostatically repel polyiodide anion, effectively blocking their shuttle to the anode and minimizing active iodine loss, while permitting unimpeded Zn 2+ diffusion.Consequently, Zn-I 2 full cells employing this multifunctional gel electrolyte achieve outstanding cycling stability, retaining 118.5 mAh•g -1 after 9000 cycles at 5 A•g -1 .This work achieves the synergistic optimization of interface issues in Zn-I 2 batteries by constructing an ion-selective multifunctional gel electrolyte, significantly enhancing their overall electrochemical performance.

Authors 11

1. Long Huang
2. Zhiyi Huang
3. Yi Xiong
4. Xiaoqiang Cai
5. Ya-Xiong Wang
6. Yan Gao
7. Jinlong Ge
8. Jie M. Zhang
9. Shuang Ma
10. Huan Wang
11. Xingxing Gu