Synthesis of mesoporous cobalt-doped manganese oxides for high-performance supercapacitors

Abstract

The mesoporous nanostructures of cobalt-doped (Co-doped) manganese oxides (MnOx) with controllable compositions are successfully synthesized by a facile inverse micelle sol-gel method. It can be found that with the addition of cobalt ions, the Mn-Co two-element spinel structure oxide is formed. Moreover, as the amount of cobalt ions increases, the shape of the agglomeration changes from rod to approximately spherical particles, and its average pore size decreases gradually, which is conducive to improve the specific surface area of the as-prepared product. The electrochemical measurements show that the specific capacitance of as-prepared mesoporous samples increases with the rise of Co-doped content. In particular, when the molar ratio of Mn/Co is 10:5, the synthesized mesoporous CoMn2O4 nanoparticles exhibit a high specific capacitance of 614.8 F g−1 at 1 A g−1. The final capacitance can still maintain 82.4% of the initial capacitance at 5 A g−1 after 5000 cycles. Furthermore, asymmetric supercapacitor assembled by CoMn2O4 and activated carbon also exhibits high energy density (29.5 Wh kg−1 at 799.7 W kg−1), high power density (8.0 kW kg−1 at 3.2 Wh kg−1) and excellent cycle stability (84.3% capacitance retention rate after 5000 cycles). The mesoporous CoMn2O4 with superior electrochemical performance has great potential in the application of high-performance supercapacitors.