Vitrified Metal–Organic Framework Composite Electrolyte Enabling Dendrite-Free and Long-Lifespan Solid-State Lithium Metal Batteries

Solid-state lithium metal batteries (LMBs) are still plagued with low ionic conductivity and inferior interfacial contact, which hinder their practical implementation. Herein, a quasi-solid-state composite electrolyte, poly­(1,3-dioxolane) (PDOL)/glassy ZIF-62 (PGZ) with fast ion transport and intimate interface contact, is fabricated via in situ polymerization. The in situ polymerization of DOL in an electrolyte matrix not only improves the exterior interface between electrolyte/electrode but also optimizes the inner interfaces among glassy particles, rendering PGZ as an uninterrupted ionic conductor. Moreover, PGZ inherits the superior ionic conductivity and the robust dendrite prohibition of glassy MOFs originating from their grain-boundary-free nature, isotropy, and abundant groups containing N species. As expected, our proposed PGZ exhibits a prominent ionic conductivity of 6.3 × 10–4 S cm–1 at 20 °C. Li|PGZ|LiFePO4 delivers an outstanding rate performance (103 mAh g–1 at 4C) and a stable cycling capacity (118 mAh g–1 at 1C over 1000 cycles). PGZ also presents excellent low-temperature cycling performance with 75 mAh g–1 for 480 cycles at −20 °C and excellent flame retardance. Even at a high loading of 12.1 mg cm–2, it can still discharge at 140 mAh g–1 for 100 cycles. Hence, PGZ prepared via in situ polymerization holds enormous prospects as a solid-state electrolyte for high-performance and safe LMBs.