Designing Compatible Ceramic/Polymer Composite Solid‐State Electrolyte for Stable Silicon Nanosheet Anodes

Abstract The commercialization of silicon anode for lithium‐ion batteries has been hindered by severe structure fracture and continuous interfacial reaction against liquid electrolytes, which can be mitigated by solid‐state electrolytes. However, rigid ceramic electrolyte suffers from large electrolyte/electrode interfacial resistance, and polymer electrolyte undergoes poor ionic conductivity, both of which are worsened by volume expansion of silicon. Herein, by dispersing Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) into poly(vinylidene fluoride)‐hexafluoropropylene (PVDF‐HFP) and poly(ethylene oxide) (PEO) matrix, the PVDF‐HFP/PEO/LATP (PHP‐L) solid‐state electrolyte with high ionic conductivity (1.40 × 10 −3 S cm −1 ), high tensile strength and flexibility is designed, achieving brilliant compatibility with silicon nanosheets. The chemical interactions between PVDF‐HFP and PEO, LATP increase amorphous degree of polymer, accelerating Li + transfer. Good flexibility of the PHP‐L contributes to adaptive structure variation of electrolyte with silicon expansion/shrinkage, ensuring swift interfacial ions transfer. Moreover, the solid membrane with high tensile limits electrode structural degradation and eliminates continuous interfacial growth to form stable 2D solid electrolyte interface (SEI) film, achieving superior cyclic performance to liquid electrolytes. The Si//PHP‐L15//LiFePO 4 solid‐state full‐cell exhibits stable lithium storage with 81% capacity retention after 100 cycles. This work demonstrates the effectiveness of composite solid electrolyte in addressing fundamental interfacial and performance challenges of silicon anodes.