Fabrication of porous MgCo2O4 nanoneedle arrays/Ni foam as an advanced electrode material for asymmetric supercapacitors

The porous MgCo2O4 nanoneedle arrays/Ni foam (MCNA@NF ) fabricated using the two-step method. Porous MgCo2O4 nanoneedle arrays have a regular diameter of 40-70 nm, and the nanoneedle is composed of numerous nanoparticles. Nitrogen adsorption-desorption surface area of the porous MgCo2O4 is about 25.6 m(2) g(-1), the volume of pores is 0.164 cm(3) g(-1). The MCNA@NF as the electrode material display 804 F g(-1) (at 1 A g(-1)). After 2000 cycles, the pours MgCo2O4 maintains 87% of initial capacitance (725 F g(-1), 6 A g(-1)). The electrochemical performances of the MCNA@NF are further investigated in an asymmetric supercapacitor (ASC). This asymmetric supercapacitor (MgCo2O4//rGO) device up to 81 Wh kg(-1) at 1350 W kg(-1). At 6750 W kg(-1), the MgCo2O4//rGO ASC device still kept 59 Wh kg(-1) (0 -1.5 V). These good ASC device performances can be attributed to the spinel structure and its high surface areas, which is beneficial for the rich redox reaction sites growth. The MCNA@NF have a good potential application in ASC devices. (C) 2018 Elsevier B.V. All rights reserved.