CuFe0.4Mn1.6O4-MWCNT composites synthesized by solvothermal method as high-performance asymmetric supercapacitors

Supercapacitor has become a promising energy storage device because of its unique advantages, and the selection of appropriate electrode materials is the key to improve the performance of supercapacitor. A series of CuFexMn2−xO4-MWCNT-y (x = 0, 0.2, 0.4, 0.6, 0.8; y = 0, 2, 3, 4) spinel composites was successfully prepared by solvothermal method. Galvanostatic charge-discharge test confirmed that CuFe0.4Mn1.6O4-MWCNT-3 modified electrode exhibited maximum specific capacitance of 656.7 F·g−1 at the current density of 1.0 A·g−1, and had good cycling stability with the capacitance retention rate of 80.6% after 5000 cycles at the current density of 8.0 A·g−1. Furthermore, the assembled CuFe0.4Mn1.6O4-MWCNT-3//activated carbon (AC) asymmetric supercapacitor possesses higher capacitance of 104.0 F·g−1 at 1.0 A·g−1 and the maximum energy density of 30.43 Wh·kg−1 and power density of 3500 W·kg−1. The outstanding conductivity and capacitative performance of CuFe0.4Mn1.6O4-MWCNT-3 may be attributed to the fact that 2D CuFe0.4Mn1.6O4 is entangled by tubular MWCNTs, thus facilitating the rapid transport of electrolyte ions, and Ni doping in CuMn2O4 leads to increased defect sites of oxygen and increased ratio of Mn4+ to Mn2+. It also indicates that CuFe0.4Mn1.6O4-MWCNT-3 composite has a potential application prospect in energy storage devices.