Single-Ion Conducting Hydrogel Electrolytes based on Slide-ring Pseudo-polyrotaxane for Ultra-long Cycling Flexible Zinc-Ion Batteries.

Abstract

Flexible zinc-ion batteries (ZIBs) with high capacity and long cycle stability are essential for wearable electronic devices. Hydrogel electrolytes have been developed to provide ion transfer channels while maintaining the integrity of ZIBs under mechanical strains. However, hydrogel matrices are typically swollen with aqueous salt solutions to increase ionic conductivity, which can hinder intimate contact with electrodes and reduce mechanical properties. To address this, we developed a single-Zn-ion conducting hydrogel electrolyte (SIHE) by integrating polyacrylamide (PAM) network and pseudo-polyrotane (PPR) structure. The SIHE exhibits a high Zn2+ transference number of 0.923 and a high ionic conductivity of 22.4 mS cm-1 at room temperature. Symmetric batteries with SIHE demonstrate stable Zn plating/stripping performance for over 160 hours, with a homogenous and smooth Zn deposition layer. Full cells with La-V2 O5 cathodes exhibit a high capacity of 439 mA h g-1 at 0.1 A g-1 and excellent capacity retention of 90.2% after 3500 cycles at 5 A g-1 . Moreover, the flexible ZIBs display stable electrochemical performance under harsh conditions, such as bending, cutting, puncturing, and soaking. This work provides a simple design strategy for single-ion conducting hydrogel electrolytes, which could pave the way for long-life aqueous batteries. This article is protected by copyright. All rights reserved.