Graphene oxide induced high dielectricity in CS/PMMA solid polymer electrolytes and the enhanced specific capacitance with Ag decorated MnCoFeO4 nanoparticles anchored graphene sheets in hybrid solid-state supercapacitors

•A hybrid supercapacitor fabricated with Ag-MnCoFeO4@rGO electrode and GO grafted CS/PMMA SPNE.•Anomalous diffusion rate and dielectric constant enhanced with GO nanofiller.•Relaxation phenomenon is dependent on the GO doping compositions in the SPNE.•Melting temperature and crystallinity reduced in GO grafted solid electrolytes.•An effective specific capacitance of 294 Fg−1 attained with Ag-MnCoFeO4@rGO nanocomposite electrode.