Solid‐state lithium metal batteries hold great promise for high‐energy‐density storage, but their practical application is hindered by the low ionic conductivity, limited Li + transference number, and unstable electrode/electrolyte interfaces inherent to composite solid electrolytes. Here, we report a highly plasticized composite solid electrolyte (denoted as PVLS) fabricated via the in situ polymerization of vinylene carbonate (PVCA), integrating succinonitrile (SN)‐LiTFSI plasticizer, and Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) nanoparticles. LLZTO surface Lewis acidity, together with cooperative SN‐PVCA solvation, promotes salt dissociation and diversified Li + coordination, while in situ curing ensures intimate interfacial contact. The optimized PVLS exhibits a room‐temperature ionic conductivity of 6.2 × 10 −4 S cm −1 , a high Li + transference number of 0.72, and an expanded oxidative stability window of 4.8 V vs Li + /Li. Spectroscopic analyses reveal enhanced populations of free TFSI ‐ anions and the formation of organic‐rich outer layers with LiF‐rich inner structures in both the CEI and SEI, which effectively regulate Li + flux. As a result, PVLS enables stable Li||Li cycling for over 1000 h and delivers superior full‐cell performance with LiFePO 4 , LiCoO 2 , and LiNi 0.9 Co 0.05 Mn 0.05 O 2 cathodes. This work presents a multiscale strategy for simultaneously balancing ionic conductivity, interfacial stability, and safety in solid‐state batteries.
Zhang et al. (Sun,) studied this question.