Dual-filler reinforced PVDF-HFP based polymer electrolyte enabling high-safety design of lithium metal batteries

Despite the high energy density of lithium metal batteries (LMBs), their application in rechargeable batteries is still hampered due to insufficient safety. Here, we present a novel flame-retardant solid-state electrolyte based on polyvinylidene fluoridehexafluoropropylene (PVDF-HFP) with nano SiO2 aerogel as an inert filler but Li6.4La3Zr1.4Ta0.6O12 (LLZTO) as an auxiliary component to enhance the ion conductivity. The introduction of SiO2 aerogels imparts the polymer electrolyte with exceptional thermal stability and flame retardancy. Simultaneously, the interaction between hydroxyl groups of SiO2 particles and PVDF-HFP creates a strong cross-linking structure, enhancing the mechanical strength and stability of the electrolyte. Furthermore, the presence of SiO2 aerogel and LLZTO facilitates the dissociation of lithium salts through Lewis acid-base interactions, resulting in a high ionic conductivity of 1.01 × 10−3 S·cm−1 and a wide electrochemical window of ∼ 5.0 V at room temperature for the prepared electrolytes. Remarkably, the assembled Li|Li cell demonstrates the excellent resistance to lithium dendrite and runs stablly for over 1500 h at a current density of 0.25 mA·cm−2. Thus, we prepare a pouch cell with high safety, which can work normally after short-circuiting under the external folding and cutting.