High-performance flexible zinc–air batteries enabled by carboxymethyl cellulose/graphene oxide composite hydrogel electrolytes

Abstract

Flexible zinc–air batteries (ZABs) have emerged as promising power sources for wearable electronics due to their high theoretical energy density (1086 W h kg⁻¹), environmental compatibility, and cost-effectiveness. However, their practical implementation is hindered by two critical challenges: uncontrolled zinc dendrite growth and electrolyte dehydration, which severely compromise cycling stability. This study proposes a novel ternary composite hydrogel electrolyte design based on carboxymethyl cellulose (CMC)/polyacrylamide (PAM)/graphene oxide (GO). The three-dimensional interpenetrating network architecture is constructed through synergistic chemical crosslinking and hydrogen bonding between oxygen-containing functional groups (–OH/–COOH) on GO nanosheets and polymer chains. When implemented in alkaline KI electrolyte, the optimized ZAB demonstrates enhanced electrochemical stability, achieving a power density of 68.7 mW cm⁻² with stable operation for 24 h at an overpotential of 0.37 V. Mechanical characterization reveals significant improvements in tensile strength (68.1 kPa) and strain (350%) compared to conventional hydrogels, while the exceptional water retention capacity (871.6% swelling ratio) effectively mitigates electrolyte dehydration. Extended evaluation in near-neutral KCl environment further confirms the hydrogel's versatility, enabling extended cycling stability exceeding 30 h. This work provides a strategic materials engineering approach for developing robust flexible energy storage systems.