Fabrication of hybrid Co3O4/NiCo2O4 nanosheets sandwiched by nanoneedles for high-performance supercapacitors using a novel electrochemical ion exchange电化学离子交换法辅助制备可用作高性能超级电容器电极的Co3O4/NiCo2O4纳米复合材料

Electrochemical ion exchange has been used to tailor the composition of transition metal oxides (Co3O4) electrode with enhanced capacity while maintaining its crystal structure and morphology. Specifically, Ni ions were incorporated to Co3O4 nanosheets sandwiched by nanoneedles to form Co3O4/NiCo2O4 composite. As positive electrode for supercapacitors, the Co3O4/NiCo2O4 composite presents a high areal capacitance of 3.2 F cm−2(1060 F g−1) at a current density of 5 mA cm−2 and outstanding rate capability as well as long cycle stability. Moreover, the assembled aqueous asymmetric supercapacitor based on Co3O4/NiCo2O4//carbon cloth electrodes delivers a considerable energy density of 3.0 mW h cm−3 at power density of 136 mW cm−3, and high rate capability (85% retention at a current density of 30 mA cm−2). A safety light composed of ten green LEDs in parallel was lit for ∼360 s using two identical supercapacitors in series, indicating a promising practical application.