Moisture-resistant and long-life fiber-shaped zinc-air batteries via electrolyte engineering
Fiber-shaped zinc-air batteries (FZABs) with aqueous electrolytes combine intrinsic safety, high energy density (1086 Wh kg−1), and environmental compatibility, making them attractive for wearable applications. However, free water in the electrolyte induces severe anode degradation while being a critical reactant for cathode redox, presenting a dilemma between anode stability and cathode functionality. The semi-open structure of FZABs allows airborne water to permeate and migrate to the anode, causing interfacial instability, while high surface area accelerates solvent evaporation, leading to increased internal resistance and salt crystallization. Consequently, typical cycle life is limited to <50 h. To overcome these challenges, we report a polymer electrolyte that captures atmospheric water as a solvent through the semi-open structure, achieved by introducing acetamide (AA), identified via unsupervised clustering algorithms, into the poly(vinylidene fluoride-hexafluoropropylene)/zinc trifluoromethanesulfonate (PVDF-HFP/Zn(OTf)2) system. AA incorporation preserves solvent-retention capability while reconstructing the Zn2+ coordination structure, promoting salt dissociation and polymer-segment mobility. Low adsorption energy of AA on zinc surfaces suppresses parasitic reactions from ambient moisture, and preferential adsorption across zinc crystal planes directs Zn2+ deposition along the (002) face, leading to uniform plating morphology. The exogenous aqueous polymer electrolyte exhibits superior mechanical properties, enabling stable output even after compression by a 1.7-t vehicle. As proof-of-concept, FZABs integrated with fiber solar cells and sensors in clothing enabled real-time health monitoring and sustainable energy utilization, demonstrating promising practical applications.