In Situ Fabricated Non‐Flammable Quasi‐Solid Electrolytes for Li‐Metal Batteries

Lithium metal batteries (LMBs) are viewed as one of the most promising high energy density battery systems, but their practical application is hindered by significant fire hazards and fast performance degradation due to the lack of a safe and compatible configuration. Herein, nonflammable quasi-solid electrolytes (NQSEs) are designed and fabricated by using the in situ polymerization method, in which 1,3,2-dioxathiolan-2,2-oxide is used as both initiator to trigger the in situ polymerization of solvents and interphase formation agent to construct robust interface layers to protect the electrodes, and triethyl phosphate as a fire-retardant agent. The NQSEs show a high ionic conductivity of 0.38 mS cm^-1 at room temperature and enable intimate solid-electrolyte interphases, and demonstrate excellent performance with stable plating/striping of Li metal anode, and high voltage (4.5 V) and high temperature (>60 °C) survivability. The findings provide an effective strategy to build high-temperature, high-energy density, and safe quasi-solid LMBs.