Ion-selective interphases engineered with vermiculite nanolayers in poly(vinylidene fluoride-co-hexafluoropropylene) electrolytes for stable solid-state lithium batteries

The advancement of lithium metal batteries is critically limited by the inherent constraints of liquid electrolytes in terms of energy density and safety, driving the pursuit of high-performance solid polymer electrolytes. Herein, a composite polymer electrolyte based on poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) matrix and two-dimensional (2D) layered vermiculite nanosheets (VS) fillers is proposed. PVDF-HFP could integrate into the interlayer spaces of VS, and build the chemical bond to create an active interface for rapid Li + transport. The negatively charged surface and high cation exchange capacity of VS augment the amount of free Li + , and endow the PVDF-HFP/VS composite electrolyte with high ionic conductivity (0.42 mS cm −1 ), large Li + transference number (0.45) at room temperature, and an expanded electrochemical window (∼5.2 V). Consequently, the corresponding Li|LiMn 0.6 Fe 0.4 PO 4 (LMFP) solid-state battery achieves a high capacity of 101.3 mAh g −1 at 5C, and the Li|LiFePO 4 (LFP) solid-state battery maintains a reversible capacity of 122 mAh g −1 even after 500 cycles at 1C, which further highlights the active role of 2D clay nanomaterials in constituting high-performance polymer electrolyte for solid-state Li battery.