Graphene enhanced hydrogel electrolyte boost flexible zinc ion battery stability

Abstract

Conventional aqueous zinc-ion batteries face challenges such as hydrogen evolution and dendrite growth, leading to poor cycling stability. To address these issues, we develop a composite hydrogel electrolyte (PCNG) with a water-poor solvation structure by integrating graphene oxide (GO) and sodium carboxymethyl cellulose (CMC–Na) into a polyacrylamide (PAM) matrix. The PCNG electrolyte utilizes a multi-hydrogen-bond network to effectively confine free water molecules, significantly suppressing zinc anode corrosion and side reactions while achieving high ionic conductivity (45.5 mS cm⁻¹). The Zn||Zn symmetric cell employing PCNG demonstrates exceptional stability over 1000 hours at 0.2 mA cm⁻². Furthermore, the three-dimensional cross-linked structure of PCNG endows it with outstanding mechanical flexibility. When paired with a graphene oxide/sodium vanadate (G@NVO) cathode, the flexible pouch cell retains a high capacity of 167.8 mAh g⁻¹ after 800 cycles at 1.0 A g⁻¹ and maintains functionality under extreme mechanical stress (e.g., bending and puncture), highlighting its potential for flexible energy storage applications. This work proposes an innovative design strategy for flexible zinc-ion batteries that harmonizes high ionic conductivity, interfacial stability, and dendrite suppression.