PVdF-HFP/exfoliated graphene oxide nanosheet hybrid separators for thermally stable Li-ion batteries

We report novel poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)/graphene oxide (GO) nanocomposite separators for lithium secondary batteries. During phase inversion of PVdF-HFP which is the origin of pore generation, GO nanosheets can be incorporated into the PVdF-HFP skeleton. The battery performances of the cells with the PVdF-HFP/GO nanocomposite separators were greatly improved compared to the pure PVdF-HFP based one. In addition, the thermal stability of the nanocomposite separators is also greatly enhanced by the addition of GO, in which the battery cells with composite separators that are thermally annealed at 150 and 180 °C function well. The inclusion of 2-dimensional GO nanosheets could also enhance the tensile strength of neat PVdF-HFP separators, leading to mechanically stable polymer separators.