Competitive coordination enhancing the thermal stability of PDOL electrolytes for safe solid-state lithium metal batteries

Poly(1,3-dioxolane) (PDOL)-based solid electrolytes hold great potential for solid-state lithium (Li) metal batteries due to their superior ionic conductivity at room temperature. However, traditional PDOL electrolytes suffer from inferior thermal stability, which has hampered their practical application. In this work, a competitive coordination mechanism is proposed to strengthen vulnerable ether oxygen bonds in PDOL chains, thereby improving the thermal stability of PDOL electrolytes. The strong coordination of Lewis base ligands on Li_6.75La₃Zr_1.75Ta_0.25O₁₂ (LLZTO) surface with Li ions weakens the ionic-dipolar interactions between PDOL chains and Li ions, conversely reinforcing the bond energy of ether oxygen bonds. Incorporating LLZTO into PDOL electrolytes effectively enhances the thermal decomposition temperature from 110 to 302 °C. Li||LiFePO₄ full cell with a 12 μm ultrathin PDOL hybrid electrolyte delivers enhanced discharge capacity and extended cycling life for 100 cycles at an elevated temperature of 60 °C. This work provides critical insights into the development of thermally stable PDOL electrolytes for safe solid-state Li metal batteries.