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

ABSTRACT

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 LiFePO ₄ |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||LiFePO ₄ 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.