Flexible mixed metal oxide hollow spheres/RGO hybrid lamellar films for high performance supercapacitors

Abstract

Mixed metal oxide hollow spheres (NiCo2O4, ZnCo2O4 and CoMn2O4)/RGO hybrid lamellar films are constructed by the method of vacuum filtration. After a simple assembling process, the mixed metal oxides are interspersed between the RGO nanosheets, which can effectively increase interlayer spacing, improve electrolyte ions penetration and fast electron diffusion. The NiCo2O4/2RGO, ZnCo2O4/2RGO and CoMn2O4/4RGO hybrid lamellar films exhibit superior electrochemical performances (1414.7 F g−1, 1075.4 F g−1 and 992.9 F g−1 at 1 A g−1) and remarkable cycling retention (90.2 %, 89.3 % and 91.2 %). Meanwhile, the asymmetric supercapacitor (ASCs) was assembled with active carbon and NiCo2O4/2RGO, which deliver maximal specific capacitance of 97.4 F g−1 (1 A g−1) and a high energy density of 34.6 Wh k g−1 at a power density of 799.0 W kg−1. Moreover, a white LED can be lit by two ASCs in series.