High-performance intercalated composite solid electrolytes for lithium metal battery

Composite solid electrolytes (CSEs) combining the advantages of both inorganic and organic solid-state electrolytes, are expected to become the most promising solid electrolyte owning to their favorable interfaces with electrodes. However, low room-temperature ionic conductivity restricts the application of CSEs in lithium metal batteries. Herein, we design an intercalated CSE based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Kaolin (2SiO2-Al2O3-2H2O), employed as an oxidative flame retardant, imparts nonflammability to the material. The polar molecule dimethyl sulfoxide (DMSO) is inserted between the kaolin layers as the preintercalation treatment, serving as an organic additive within the PVDF-HFP based SPE. The intercalated structure of CSE provides rapid Li+ transport channels, resulting in a high ionic conductivity (8.58 x 10-4 S cm- 1) and large Li+ transference number at room temperature. The Li||Li symmetrical cell with prepared CSE exhibits outstanding cyclic stability of over 1400 h at a current density of 0.2 mA cm-2 for the capacity of 0.2 mAh cm-2. Moreover, the assembled Li||LiFePO4 cell delivers a high initial capacity of 140.5 mAh g-1 with a capacity retention of 81.2 % after 800 cycles at 0.5 C. In this paper, we present a novel approach for constructing high-performance solid-state lithium metal batteries.