A stretchable and self-healing polymer-in-salt all-solid electrolyte for wearable zinc-ion batteries

In developing solid polymer electrolytes (SPEs), polymer-in-salt configuration is valued for their high ionic conductivity and energy density. Nevertheless, an overabundance of salt may weaken the mechanical strength of electrolyte and affect the safety of battery, improving their mechanical endurance is crucial for gaining wider acceptance in the market. In this context, we have developed a novel elastic polystyrene-block-polyisoprene (SIS) electrolyte with an 80% loading of Zn(TFSI)₂,  termed as 80%-Zn(TFSI)₂-SIS, where polyisoprene (PI) segments can effectively combine with Zn(TFSI)₂, the polystyrene (PS) segments act as connectors, conferring the solid-state electrolyte with robust mechanical properties capable. The 80%-Zn(TFSI)₂-SIS exhibits commendable ionic conductivity of 1.89×10^-4 S cm^-1 at room temperature, a high ion transference number of 0.83, exceptional elongation at break of 842% and thermally activated self-healing capabilities. Crucially, all-solid-state zinc-ion batteries (ZIBs) utilizing the 80%-Zn(TFSI)₂-SIS electrolyte exhibit exceptional cycle stability, maintaining 106 mAh g^-1 after 400 cycles, and retain performance up to 70°C. Meanwhile, the assembled cell with 80%-Zn(TFSI)₂-SIS electrolyte can demonstrate exceptional robustness and safety even under extreme conditions, including cutting, bending, stretching and water immersion, which underscores their potential for applications in wearable zinc-ion batteries (ZIBs).