A novel PVdF-based composite gel polymer electrolyte doped with ionomer modified graphene oxide

In this paper, a novel composite gel polymer electrolyte (CGPE) was prepared by doping ionomer-modified-graphene (IMGO) into poly(vinylidenefluoride) (PVdF) according to a phase separation technique. As to the doped IMGO, the original sp2 equipotential network of the GO component can be damaged with the grafted ionomer, while, due to the sheet-like morphology, the prepared IMGO can act as the ion-conducting channel in the final CGPE system. The effect of IMGO on the morphology, mechanical and electrochemical performance of the prepared CGPE were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), a differential scanning calorimeter (DSC) and thermogravimetry (TGA), a mechanical tensile test, AC-impedance, linear sweep voltammetry (LSV), and so on. When the relative content of IMGO was at 10 wt%, the prepared CGPE showed the highest ionic conductivity (3.35 × 10−3 S cm−1), and the electrochemical window could be stable up to 4.8 V. The assembled polymer lithium-ion batteries based on it delivered the highest charge–discharge capacity (168.4 mA h g−1) and the capacity retention of the cells (LiCoO2/CGPE/Li) could be maintained by up to 90% after 50 cycles.