A High-Performance Polymer Electrolyte Membrane Enhanced By Graphene Oxide Doped By Redox Species

A high-performance electrolyte membrane was synthesized by combining poly (vinylidene fluoride)/Lithium bis(trifluoromethanesulfonyl)imide (PVDF)/LITFSI electrolyte with graphene oxide (GO), and the lithium salt of tungstosilicic acid (SiWLi). The impact of the addition of GO/SiWLi on the microstructure, crystallinity, and morphology were characterized by Fourier transform infrared spectra (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was found that homogeneously distributed GO contributed to a reduction of the pore size and crystallinity of polymer electrolyte membrane. The addition of GO/SiWLi to a conventional polymer electrolyte membrane not only resulted in an increased ionic conductivity from 0.93x10-2 S cm-1 to 3.12x10-2 S cm-1, but also an increased lithium ion transference number from 0.549 to 0.895. The membranes with and without GO/SiWLi were used to fabricate planar all solid-state supercapacitors (SCs) and Li-ion batteries. The all-solid-state SCs fabricated with the membrane containing GO/SiWLi displayed a much lower internal resistance than those fabricated with the membrane without GO/SiWLi. As a result of the reduced resistance, the specific capacitance of the SCs with the membrane containing GO/SiWLi was 30% greater than that of the SCs without GO/SiWLi. When evaluated in a Li-ion battery configuration, the high-performance electrolyte membrane led to a two-fold increase in the achievable capacity utilizing galvanostatic conditions ranging from a 5 C-rate to 20 C-rate.