Interface Modulation and Lithium Dendrite Suppression of LLTO via Synergistic KH560-PDA Co-Grafting for PVDF-HFP Composite Solid Electrolytes.

Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer electrolytes suffer from low ionic strength and poor mechanical performance. Meanwhile, lithium lanthanum titanate (LLTO) fillers exhibit severe agglomeration and weak interfacial compatibility with the polymer matrix. To solve these problems, 3-glycidoxypropyltrimethoxysilane (KH560) at four different concentrations (1 wt%, 2 wt%, 3 wt%, 4 wt%) was loaded onto polydopamine-modified LLTO (PDA@LLTO). The modified materials were mixed with PVDF-HFP, and composite solid electrolytes were fabricated by the solution casting method. The epoxy groups in KH560 undergo ring-opening reactions with amino and hydroxyl moieties on PDA, while its trimethoxysilane groups crosslink with the polymer matrix, forming a robust "LLTO-PDA-KH560-polymer" interfacial structure. This dual modification markedly improves the dispersion of PDA@LLTO, strengthens interfacial adhesion, and enhances the mechanical and electrochemical properties of the composite electrolyte. All KH560 loadings suppress LLTO agglomeration, and the 3 wt% grafting ratio yields the optimal performance: a uniform and dense microstructure, a room-temperature ionic conductivity of 5.92 × 10