Hybrid MnO2@NiCo2O4 nanosheets for high performance asymmetric supercapacitors

Abstract

NiCo₂O₄ is a promising material for supercapacitors because of its high theoretical capacity. However, this material often suffers from low cycling stability. In this work, hybrid MnO₂@NiCo₂O₄ nanosheets grown on Ni foam have been synthesized through a facile hydrothermal approach. The MnO₂@NiCo₂O₄ electrode delivers a high specific capacitance of 3086 mF cm⁻² at a current density of 2 mA cm⁻², and the as-assembled asymmetric supercapacitors yield a high energy density of 72.1 W h kg⁻¹ and an excellent cycle life with a 97.3% capacitance retention after 6000 cycles. The outstanding electrochemical performance could be attributed to the unique hybrid structures of the electrode materials. This shows that the MnO₂@NiCo₂O₄ hybrid structures as the electrode materials might be potentially useful for next generation high performance supercapacitors.