MOF-derived multifunctional filler reinforced polymer electrolyte for solid-state lithium batteries

Solid-state lithium batteries (SSLBs) have attracted great interest from researchers due to their inherent high energy density and high safety performance. In order to develop SSLBs, the following two key problems should be solved: (1) Improving the lithium ion conductivity of solid electrolyte at room temperature; and (2) improving the interface between the electrode and the electrolyte. Herein, we propose a new multifunctional filler for reinforcing polymer electrolytes. The composite solid electrolytes (CSEs) mainly contain a MOF-derived Co-doped hollow porous carbon nanocage, which absorbs Li⁺ containing ionic liquid (Li-ILs@HPCN), polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imide. By optimizing the composition of the CSEs, the CSEs membrane with high ionic conductivity (1.91 × 10⁻⁴ S cm⁻¹ at 30 °C), wide electrochemical stability (5.2 V) and high mobility of lithium ion (0.5) was obtained. Even at a current density of 0.2 mA cm⁻², the PILH electrolyte possesses excellent interfacial stability against Li metal in Li symmetrical batteries exceeds 1600 h. Finally, the SSLBs (LFP/PILH/Li) showed excellent cycle stability, and the capacity was maintained at 152.9 and 140.0 mA h g⁻¹ after 150 cycles at a current density of 0.2C and 0.5C. This work proposes a completely new strategy for building high-performance SSLBs.