Boosting the cycling stability of all-solid-state lithium metal batteries through MOF-based polymeric protective layers

Solid-state electrolytes (SSEs) play a pivotal role in advancing next-generation lithium metal battery technology. However, they commonly encounter substantial interfacial resistance and poor stability when interfacing with lithium metal, hindering practical applications. Herein, we introduce a flexible metal−organic framework (MOF: NUS-6)-incorporated polymeric layer, denoted as NP, designed to protect the sodium superionic conductor (NASICON)-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolyte from Li metal anodes. The NP matrix establishes a soft interface with the LATP surface, effectively reducing voids and gaps that may arise between the LATP electrolyte and Li metal. Moreover, the MOF component in NP enhances ionic conductivity, offers abundant Li+ transport sites, and provides hierarchical ion channels, ensuring a homogeneous Li+ flow and thus effectively inhibiting Li dendrite formation. Utilizing NP, we fabricate Li symmetrical cells cycled for over 1600 h at 0.2 mA cm−2 and all-solid-state Li|NP-LATP|LiFePO4 batteries, achieving a remarkable 99.3% capacity retention after 200 cycles at 0.2 C. This work outlines a general strategy for designing long-lasting and stable solid-state Li metal batteries.