Melamine Foam-Scaffolded LDHs@PVA Gel Electrolyte with High Ionic Conductivity and Water Retention Capability for Flexible Zinc-Air Batteries

Abstract

Flexible zinc-air batteries (FZABs) are hindered by complex interfacial challenges among the zinc anode, air cathode, and solid-state electrolyte, particularly structural instability and sluggish charge transfer kinetics that severely compromise their operational durability and energy efficiency. Herein, we propose a rationally designed three-dimensional integrated architecture featuring a melamine foam (MF)-supported CoNi-layered double hydroxide (LDH) scaffold embedded within a polyvinyl alcohol (PVA) gel polymer electrolyte (MF-LDHs@PVA GPE). The highly oriented, hydrophilic CoNi-LDH arrays are in situ integrated within the porous MF framework, providing fast ionic diffusion channels and resulting in an exceptional ionic conductivity of 68.3 mS cm-1. Simultaneously, covalent crosslinking between LDH hydroxyl groups and MF/PVA chains through hydrogen bonding endows the GPE with mechanical flexibility and water retention capability. The layered architecture of LDHs/MF facilitates electrode–GPE interfacial compatibility and charge homogeneity, partially suppressing zinc dendrite formation. These outstanding characteristics enables the MF-LDHs@PVA-based FZAB to achieve a 36-hour cycle life and a high power density of 61.4 mW cm-2. Moreover, the assembled sandwich-type battery demonstrates robust performance under extreme working conditions without significant electrochemical degradation, highlighting its significant potential for flexible wearable devices.