A 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 138.87 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 enable 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.