Rare earth ions-reinforced polycationic gel polymer electrolytes for enhancing ionic conductivity and zinc anode interface stability in flexible zinc-air batteries

Abstract

Flexible zinc-air batteries (FZABs) stand out as strong candidates for future high-performance flexible energy storage devices, owing to their high safety, high energy density and low cost. However, the electrochemical performance of FZABs is hampered by the lack of gel polymer electrolytes (GPEs) with efficient ion transport and the presence of zinc dendrite growth issues in an alkaline environment. Herein, by incorporating rare earth ions of La³⁺ and Ce³⁺ into the polycationic gel polymer frameworks, a novel cationic CPAM-LC GPE with enhanced ion transport is constructed through the dynamic competitive coupling mechanism to achieve rapid transport of hydroxide ions. The CPAM-LC GPE exhibits prime ionic conductivity (327 mS cm⁻¹), excellent mechanical properties and interfacial adhesion. Moreover, the FZAB with CPAM-LC GPE shows superior performance, achieving a maximum power density of 203.4 mW cm⁻² and over 1300 charge–discharge cycles. Most importantly, the synergistic effect of La³⁺ and Ce³⁺ with polycationic chains in the CPAM-LC GPE can effectively regulate the deposition behavior of Zn(OH)₄²⁻, thereby significantly enhancing the reversibility of the zinc anode. Thus, this strategy using rare earth ions in polycationic GPEs offers a valuable reference for developing high-performance, interfacial stable FZABs in strong alkaline electrolytes.