Flame-Retardant Quasi-Solid-State Electrolytes From Self-Assembled Azolate Hybrid Frameworks for Highly Safe Lithium Batteries.

Achieving quasi-solid-state electrolytes (QSSEs) that simultaneously deliver fast ion transport and intrinsic thermal safety remains a central challenge for lithium batteries, as improvements in ionic conductivity are often coupled with increased flammability and interfacial instability. Here, we present a spray-assisted in situ assembly strategy to construct azolate hybrid frameworks (AHFs) directly on glass fiber substrates, followed by thermal polymerization to yield a chemically integrated QSSE. The heterocyclic AHF provides ordered lithium-philic coordination sites and continuous ion-transport pathways, enabling efficient Li+ migration while maintaining high thermal robustness. As a result, the resulting LiFePO4|FP10v-GF|Li cell sustains stable cycling for over 500 cycles at 25°C and 100 cycles at 60°C. Notably, the framework architecture enables molecular level confinement of triethyl phosphate (TEP) as a flame-retardant component, establishing a nitrogen phosphorus synergistic flame-retardant mechanism without compromising electrochemical compatibility. Consequently, high-loading Li||LiFePO4 cells exhibit stable cycling under practical conditions (E/C = 0.56 g Ah-1, N/p = 3.27) and successfully withstand accelerated rate calorimetry tests from 25°C to 300°C without thermal runaway. This work demonstrates how framework chemistry and molecular confinement can be synergistically integrated to decouple ionic conductivity from flammability, providing a general design principle for intrinsically safe, high-energy quasi-solid-state lithium batteries.