Laminar composite solid electrolyte with succinonitrile-penetrating metal-organic framework (MOF) for stable anode interface in solid-state lithium metal battery

Succinonitrile (SN) plastic crystal electrolyte holds great promise for high-performance solid-state lithium metal batteries due to its high ionic conduction. However, the serious side reaction between SN and lithium anode always causes large interfacial resistance, deteriorating the battery capacity. Herein, we penetrated LiTFSI-SN (LSN) electrolyte into the interlayer channels of laminar metal-organic framework (MOF), then an ultra-thin and stable laminar LiTFSI–SN–MOF composite solid-state electrolyte (LSN-MOF CSE) was obtained. We demonstrate that the interlayer nanochannels for LSN electrolyte storage without sacrificing the mobility of SN molecules. Meanwhile, the unsaturated coordination of MOF, induced by Co/Ni metal sites, causes a horizontal arrangement of SN. Therefore, this electrolyte offers a remarkable ionic conductivity of 7.41 × 10−4 S cm−1 at 25 °C. Moreover, the interlayer nanochannels and covalent interaction of MOF synergistically suppress the migration of SN to lithium anode, thus improving the interface stability of lithium anode. Importantly, the assembled Li symmetrical cell performs stable operation over 800 h under 0.2 mA cm−2, and the LiFePO4/Li cell delivers excellent cycling stability of 148.2 mAh g−1 with a low capacity decay of 0.048% per cycle after 200 cycles under 0.2C and 25 °C.