Reinforcing electrolyte skeleton via in-situ cross-link enhancement for solid-state lithium metal batteries

Owing to excellent compatibility with lithium metal anodes, ether-based polymer electrolytes have attracted considerable attention. Nevertheless, their narrow electrochemical stability window leads to a severe mismatch with high cut-off voltage operating conditions, restricting their further application in high-energy-density batteries. Herein, a novel cross-linked polyether solid electrolyte TPDOL is proposed, where N,N-diglycidyl-4-glycidyloxyaniline (TGAP) is introduced during the in-situ polymerization of 1,3-dioxolane (DOL). With the augmentation of cross-link sites induced by TGAP, a three-dimensional network architecture of TPDOL is well designed and provides stable channels for Li⁺ transport, while its oxidative stability is much improved (>4.6 V). Notably, TPDOL favors an anion-rich solvation environment, promoting a uniform and LiF/Li₃N-rich solid electrolyte interphase (SEI) generation. Hence, Li|TPDOL|LiFePO₄ cells enable excellent cycling performance, with significantly enhanced capacity retention of 87% after 400 cycles at 1C, and Li|TPDOL|LiNi_0.8Co_0.1Mn_0.1O₂ cells ensure greatly improved compatibility under high cut-off voltage, with capacity retention of 82% after 200 cycles at 0.5C within 3.0–4.3 V. This work introduces a promising polymer electrolyte system for developing high-energy-density and safe lithium metal batteries.