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.

Solid-state lithium batteries with solid electrolytes are expected to enhance the battery safety and energy density as one of the most promising next-generation batteries. Among various solid-state electrolytes, sulfide solid electrolyte is considered as promising candidate due to its ultra-high ionic conductivity. However, its large-scale production is restricted due to its fragility and difficulty in processing, which affects its application in solid-state batteries. Recent work indicates that the flexibility of solid electrolytes can be realized via introducing flexible polymers or supporting frameworks in solid electrolytes membranes, constituting a solution to the embrittlement challenge in large-scale and thin-film electrolyte preparations. Therefore, developing flexible solid electrolytes is one of the important strategies to promote the industrialization of solid-state batteries. This review introduced the physical/chemical properties and development of sulfide solid electrolytes, summarized the related research work on polymer self-supporting method and flexible skeleton-supporting method in the flexibility of solid electrolytes, and discussed the technical characteristics and advantages/disadvantages of wet/dry processes in the flexible sulfide solid electrolyte preparation, respectively. In addition, the future development aspects were also given to promote the practical application of solid-state lithium batteries.