Activated metal-organic frameworks (a-MIL-100 (Fe)) as fillers in polymer electrolyte for high-performance all-solid-state lithium metal batteries

As a common filler in polymer electrolytes, Metal-organic frameworks (MOFs) has been studied extensively in recent years. In this study, we propose a novel solid composite electrolytes (SCEs) based on PEO/LiTFSI/a-MIL-100 (Fe)/PVDF by using a straightforward solution-casting method. Unactivated and activated MIL-100 (Fe) (a-MIL-100 (Fe)) as the fillers were compared, and the interactions of functional groups of unactivated MIL-100 (Fe) and a-MIL-100 (Fe) with anions of electrolyte salts through Lewis acid-base interaction are studied with density functional theory (DFT) calculations. The influences of different a-MIL-100 (Fe) contents on electrochemical performances were also examined. The Li/SCEs/LiFePO4 cell displayed high average discharge capacities of 161.8 mAh g−1, 166.8 mAh g−1, 158.9 mAh g−1, 146.2 mAh g−1 and 92.6 mAh g−1 at the rate of 0.1, 0.2, 0.5, 1 and 2 C at 60 ℃, respectively, without liquid electrolytes. This work might provide new insight into the role of activated MOFs fillers in polymer electrolytes.