Electrochemical characterization of Li-ion conducting polyvinylidene fluoride/sulfonated graphene oxide nanocomposite polymer electrolyte membranes for lithium ion batteries

Abstract

In this study, Li-ion conducting poly (vinylidene fluoride) (PVDF)/sulfonated graphene oxide (SGO) nanocomposite polymer electrolytes (PE) are prepared, and the influences of SGO content on the physical and electrochemical properties of PE composites are investigated using multi-techniques. SGO is synthesized using a modified Hummers' method followed by sulfonation using sulfanilic acid as a precursor. Results reveal that the morphology, tensile strength, ionic conductivity, Li-ion transference number, and electrochemical stability of the prepared PE composites are significantly altered by changing SGO content. PVDF/SGO-based PE containing 0.004 wt% SGO shows the best physicochemical and electrochemical characteristics and provides excellent ionic conductivity of 6.20 mS cm−1 and Li-ion transference number close to unity, at room temperature. The electrochemical behavior of the best PVDF/SGO PE in the LiMnO2/PE/Li cell is compared with bare PVDF- and PVDF/GO-based cells prepared at the same conditions. PVDF/SGO-based cell exhibits a high discharge capacity of 204 mAh g−1 at 0.1 C, which is considerably higher than those obtained from other cells. This cell shows capacitance retention of about 98.5% and columbic efficiency of about 97.4% after 100 cycles and delivers an energy density of about 512.0 Wh kg−1 at a power density of 56.6 W kg−1.