In Situ Dual Crosslinked Composite Quasi‐Solid Electrolytes Enable Multiple Continuous Ion Transport Channels for Ultra‐Long Cycle and High Load Lithium Metal Batteries

Composite quasi‐solid electrolytes (CQSEs) have emerged as promising candidates for solid‐state lithium metal batteries (SSLMBs) through synergistic integration of inorganic fillers and polymer matrices. However, intrinsic interfacial incompatibility between organic/inorganic phases impedes continuous Li⁺ migration pathways, leading to compromised ionic dynamics and cycling stability. In this work, surface‐modifiable lithiated zeolite (LiZSM‐5) is utilized for functional group grafting and designing a hemiacetal‐amine polymer (Trimer) with fast ion conduction. A dual‐crosslinked CQSE with multiple continuous Li+ transport channels through integrated zeolite frameworks and polymeric conduction networks has been obtained by in situ polymerization. Combined experimental and computational analyses reveal that the abundant copolymer chain segments synergistically interact with Lewis acid sites on LiZSM‐5, optimizing Li⁺ transport pathways to achieve exceptional ionic conductivity (3.7 mS cm−1) and Li⁺ transference number (0.89). The optimized CQSE enables ultralong cycling stability exceeding 11 000 h in Li symmetric cells and sustains 800 cycles in LiNi0.8Co0.1Mn0.1O2|CQSE|Li full cells at 0.5 C with high active material loading. Remarkably, 1 Ah soft‐pack battery displays excellent cycling stability alongside excellent safety characteristics under mechanical abuse tests. This interfacial engineering strategy provides fundamental insights into constructing continuous ion‐transport networks through organic/inorganic phase coordination, suggesting promising avenues for a scalable high‐energy‐density battery.