Self-assembled novel dandelion-like NiCo2O4 microspheres@nanomeshes with superior electrochemical performance for supercapacitors and lithium-ion batteries

Abstract

Binary metal oxides have been regarded as potential electrode materials for supercapacitors and lithium-ion batteries, which can ameliorate and compensate the deficiency of electrochemical performance of single metal oxides, such as reversible capacitance/capacity, structural stability and electronic conductivity. In this work, we report a facile solvothermal method to synthesize hierarchical dandelion-like NiCo₂O₄ microspheres@nanomeshes (NCO-M@N) with a high surface area (105.2 m² g⁻¹), which exhibit superior pseudocapacitive performance with high specific capacitance (2184 F g⁻¹), remarkable rate capability and excellent cycling performance (94.2% retention after 4000 cycles), meanwhile, displaying excellent energy storage properties for lithium-ion batteries, such as admirable rate performance (785 mA h g⁻¹ at a current density of 2000 mA g⁻¹) and an outstanding capacity retention of 88% after 100 cycles. Most importantly, when the NCO-M@N//AC asymmetric supercapacitor is prepared, it exhibits the highest energy density (45.3 W h kg⁻¹) at a power density of 533.3 W kg⁻¹ and good cycling stability (89% of the initial capacitance retention at 5 A g⁻¹ over 4000 cycles), indicating its potential applications for next-generation high power supercapacitors and lithium-ion batteries. The strategy is simple but very effective, and thus it can be extended to other high-capacity metal oxide materials.