Exploration, of magnetic sesquioxide nanocomposite as a potential electrode material for the fabrication of high energy density asymmetric supercapacitors

•Fe2O3-Cr2O3 Nanocomposite was synthesized by facile hydrothermal method.•Fe2O3-Cr2O3 NC has spherical shaped morphology.•Fe2O3-Cr2O3 NC delivers high specific capacitance of 906.9F/g.•Fe2O3-Cr2O3 NC exhibits capacitive retention of about 79.2% for 5000 charge–discharge cycles.•Fe2O3-Cr2O3//AC ASC delivers the energy density of 77.17 Wh/kg corresponding to the power density of 650 W/kg.