Bio-Inspired Bidirectional Proton Regulatory Mechanisms by Anhydride-Based Hydrogel Electrolytes for High-Performance Aqueous Zinc-Ion Batteries.

Abstract

Aqueous zinc-ion batteries (AZIBs) employing hydrogel electrolytes offer significant advantages in mitigating short-circuit and electrolyte leakage risks. Nevertheless, the sluggish transport kinetics of Zn2 + and severe interfacial instability of zinc anodes still severely restrict their further development. Herein, a bio-inspired hydrogel electrolyte based on poly(acrylamide-co-maleic anhydride) (P(AM-co-MA)) copolymer is fabricated to construct a dual-functional polymer network. The dynamic acid-base equilibrium between carboxyl and amide groups enables reversible bidirectional proton buffering, which effectively suppresses the hydrogen evolution reaction and anode corrosion. Meanwhile, the synergistic Zn2 + hopping sites constituted of carboxylate and amide groups optimize the ion-transport microenvironment and accelerate Zn2 + migration kinetics synchronously, realizing the coordinated regulation of proton activity and Zn2 + transport. Thus, the optimized P(AM-co-MA) hydrogel electrolyte delivers a high Zn2 + transference number of 0.66 and an ionic conductivity of 16 mS cm-1. The assembled Zn||Zn symmetric cells achieve ultra-long and stable cycling for over 2700 h at 1 mA cm-1. Furthermore, the pouch-type Zn||NaV3O8 full cells based on this hydrogel electrolyte exhibit a high specific capacity of 254 mAh g-1 at 1 A g-1, with a capacity retention of 80% after 120 cycles, verifying the great application potential of this rational design for flexible energy storage devices.