Rapid Self-Healing Gel Electrolyte Based on Deep Eutectic Solvents for Solid-State Lithium Batteries

A deep eutectic solvent (DES) is a promising electrolyte choice for lithium metal batteries. However, the DES liquid electrolyte causes safety concerns and side reactions with the lithium anode. Therefore, it is necessary to solidify the DES-based electrolyte and enhance its electrochemical stability. Herein, we present a novel DES-based rapid self-healing gel electrolyte, which is able to self-smooth its surface cracks in only 30 min. The electrolyte exhibits noncombustibility (SET = 4 s g^-1), high ionic conductivity (1.1 × 10^-3 S cm^-1 at 25 °C), and a wide electrochemical voltage window (4.5 V vs Li/Li⁺). As a result, the solid-state lithium batteries coupling the gel electrolyte with the Li anode and LiFePO₄ cathode deliver a high specific capacity of 135.4 mA h g^-1 with durable cyclic stability (>1200 h). This work provides valuable insights for design of fire-resistant and high-energy solid-state lithium batteries.