Polyvinyl Butyral/SiO2 Nanoparticles Composite Coating on Poly(vinylidene fluoride) Separators for Lithium-Ion Batteries

Polyvinyl butyral (PVB) with high viscosity was employed as a polymeric binder to stick SiO2 nanoparticles onto the surfaces of poly(vinylidene fluoride) (PVDF) separators prepared by a phase inversion method for Li-ion batteries. The morphology, wettability, thermal stability, ionic conductivity and electrochemical properties of the composite separators were analyzed. These results indicated that the SiO2 nanoparticles were firmly attached by the PVB binder and uniformly dispersed on the surfaces of the PVDF separator, so the SiO2-PVB coated PVDF separator exhibited significantly improved hydrophilicity and electrolyte wettability, and better thermal stability and ionic conductivity than those composed of PVDF only enhance. More importantly, the cell using the SiO2-PVB coated PVDF separator displayed a better cycling performance and higher discharge capacity rate capability, which indicated the SiO2-PVB coating could enhance the physical and electrochemical performance of PVDF separators used in Li-ion batteries.