Wenqing Wang, Xiangyang Li, Zheshuai Lin, Ying Li, Jianhua Cao, Dayong Wu
Abstract Coating the separator surface of high‐energy‐density lithium batteries with a solid‐state inorganic ion conductor can enhance the ionic conductivity and lithium‐ion transference number, while improving interfacial contact between the separator and electrodes. However, during battery cycling, high‐valence metal ions in the solid‐state ion conductor are prone to reduction by metallic lithium, leading to performance degradation. In this study, the applicability of inorganic solid‐state electrolytes, such as Li 1 . 3 Al 0 . 3 Ti 1 . 7 (PO 4 ) 3 (LATP), compounded with Ag‐MOF on the lithium metal anode side is investigated. Experimental results demonstrate that a composite separator with an Ag‐MOF:LATP mass ratio of 8:92, when assembled in Li||Li symmetric cells, exhibits stable cycling for over 1200 h at 0.5 mA cm −2 . Furthermore, in NCM811||Li batteries, after 300 cycles at 0.5C and 500 cycles at 5C, the capacity retention rates remain at 70.9% and 76.1%, respectively. The functional mechanism of Ag‐MOF involves formation of an Ag‐Li alloy during cycling, which suppresses Ti⁴⁺ reduction and enhances cycling stability. The most significant finding is that the disassembled composite separator can be reused for two additional charge‐discharge cycles after battery cycling, exhibiting outstanding reusability with a capacity retention rate consistently exceeding 70% after 500 cycles at 5C rate.