Competitive Anion Anchoring and Hydrogen Bonding in Multiscale‐Coupling Composite Quasi‐Solid Electrolytes for Fire‐Safety and Long‐Life Lithium Metal Batteries

Composite solid-state electrolytes (CSEs) using Li_1+xAl_xTi_2-x(PO₄)₃ (LATP) as active fillers offer promising prospects for large-scale lithium metal batteries (LMBs) applications due to their high environmental stability, cost-effectiveness, and improved safety. However, the challenges persist owing to high interfacial resistance with electrodes and instability with lithium metal. Herein, self-assembly nanofiber/polymers/LATP composite quasi-solid electrolytes (SL-CQSEs) are reported through in situ polymerization of precursor solution containing vinylene carbonate (VC), fluoroethylene carbonate (FEC), lithium bis(trifluoromethanesulfonic) imide (LiTFSI) in a porous and flexible self-supporting skeleton (SSK) consisting of 2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate (UPyMA)'s self-assembly nanofiber (SAF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and LATP. Anion-anchoring/hydrogen-bonding competition and intercomponent multiscale-coupling effects on SL-CQSEs are found, which contribute to their incombustibility, excellent room-temperature ionic conductivity (1.03 mS cm^-1), wide electrochemical window (5.1 V), good interfacial compatibility, and lasting inhibition of lithium dendrites. LiFePO₄/Li cells with SL-CQSEs not only exhibit high-rate performance and long-term cycling stability, with a capacity retention of 90.4% at 1C and 87% even at 4C after 1000 cycles, but also can resist fire and mechanical abuse, highlighting the potential applications of SL-CQSEs for high-performance and safety LMBs.