hanguo Ji, Hao Luo, Shuo Qin, Xinyue Zhang, Yuanyuan Hu, Weiwei Zhang, Jianchao Sun, Jing Xu, Haijiao Xie, Zhenhua Yan, Kai Yang

Abstract

The active H2O and slow ion kinetics behavior deteriorate the performance of aqueous zinc-ion batteries at a wide temperature range, even in hydrogel electrolyte. Herein, a component fluctuation modulated gelation effect is applied to optimize Zn2+ solvation structure, realizing a balance between H2O activity limitation and Zn2+ kinetics retention. The as-prepared hydrogel electrolyte via in situ copolymerization of [2-(methacryloyloxy)ethyl] dimethyl-(3-sulfopropyl) and acrylamide in the electrolyte salt matrix facilitates stable overall performance at both normal and low temperatures. Theoretical calculations and experimental results attest that polymer functional groups exhibit a higher efficacy in substituting bound water in the Zn2+ solvated shell with the polymer content increasement, thereby alleviating water-associated parasitic reactions. Furthermore, the hydrogel with abundant zwitterionic groups not only interacts with H2O to limit hydrolysis, but also constructs separated ionic migration channels to promote uniform and fast Zn2+ transport. As a result, the hydrogel electrolytes promote stable Zn2+ plating/stripping behaviors over 1050 h and 3000 h at 25 and −20 °C, respectively. The full batteries achieve a capacity retention of 98.8% over 2000 cycles at 25 °C and stably cycle for 600 times at −20 °C. This work yields novel insights into the development and design of hydrogel electrolytes.

Paper Linkage: https://onlinelibrary.wiley.com/doi/full/10.1002/aenm.202400063