Novel composite separator for high power density lithium-ion battery

Abstract

High power density is essential for next-generation lithium-ion batteries. However, it is a great challenge to achieve high-power density and safety lithium-ion batteries due to the lack of reliable separators with uniform porosity, strong mechanical flexibility, and superior electrolyte uptake. Herein, a poly (vinylidene fluoride-co-hexafluoropropylene)/graphene oxide separator with uniform porosity, strong mechanical flexibility, and superior electrolyte uptake is prepared. The incorporation of graphene oxide into a poly (vinylidene fluoride-co-hexafluoropropylene) separator provides a large number of uniform diffusion channels for lithium ions to pass through by reducing the degree of crystallinity and increasing the pore uniformity of separator. In addition, the separator has superior mechanical property and thermal stability in comparison to commercial Celgard 2325 and pure poly (vinylidene fluoride-co-hexafluoropropylene) separators. This LiFePO4/Li cell with the prepared poly (vinylidene fluoride-co-hexafluoropropylene)/graphene oxide separator delivers a high capacity up to 160 mAh g−1 at 0.5C at room temperature and can be fully charged/discharged in 6 min (10C).