Porous NiCo2O4 nanowires supported on carbon cloth for flexible asymmetric supercapacitor with high energy density

Abstract

Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays structure design can effectively enhance the utilization of active material. In this article, we synthesis a porous NiCo2O4 nanowires arrays, which were intimate contact with flexible carbon cloth (CC) by a facile hydrothermal reaction and calcination treatment. The rational array structures of NiCo2O4 facilitate the diffusion of electrolyte and effectively increase the utilization of active material. The as-obtained NiCo2O4@CC electrode exhibits a high capacitance of 1183 mF cm−2 and an outstanding capacitance retention of 90.4% after 3000 cycles. Furthermore, a flexible asymmetric supercapacitor (ASC) using NiCo2O4@CC as positive electrode and activated carbon cloth (ACC) as negative electrode was fabricated, which delivers a large capacitance of 750 mF cm−2 (12.5 F cm−3), a high energy density of 0.24 mWh cm−2 (3.91 mWh cm−3), as well as excellent cycle stability under different bending states. These remarkable results suggest that as-assembled NiCo2O4@CC//ACC ASC is a promising candidate in flexible energy storage applications.