In situ synthesis of gel polymer electrolyte for lithium-metal anodes with a sulfide-enhanced interface via thiol–ene click chemistry

The high theoretical capacity of Li-metal batteries (LMBs) makes them promising alternatives to Li-ion batteries to meet the increasing demand for advanced energy storage devices. However, high-energy-density LMBs with liquid electrolytes (LEs) are affected by dendrites produced during the inhomogeneous electrochemical deposition of Li. Herein, a novel S-containing gel polymer electrolyte (GPE) is synthesized in situ via thiol–ene click chemistry. The prepared S-containing GPE enables uniform Li deposition, and the resulting Li/Li symmetric cell can show cyclic stability for more than 500 h at a current density of 1 mA cm⁻². Furthermore, the fabricated GPE-based LiFePO₄/Li cells exhibit capacity retention of up to 91% after 500 cycles at 0.5C, indicating satisfactory stability compared to LE-based cells. The high electrochemical performance of the cells with GPE can be attributed to the formation of a sulfide and organo (poly)sulfide-reinforced hybrid solid electrolyte interface layer, which effectively stabilizes the interface and inhibits the formation of Li dendrites.