High-performance asymmetric supercapacitors assembled with novel disc-like MnCo2O4 microstructures as advanced cathode material

Herein, porous MnCo2O4 with disc-like (MnCo2O4-discs) and ring-like (MnCo2O4-rings) microstructures were respectively synthesized using an initial hydrothermal method at different temperatures and a calcination treatment in air. The electrochemical properties of these MnCo2O4 materials were investigated in three-electrode and two-electrode systems, and as such, MnCo2O4 presented a battery-like electrochemical response. The specific capacity of MnCo2O4-discs was determined to be 296.1C/g at 1 A/g, superior to 246.3C/g for MnCo2O4-rings. An asymmetric supercapacitor (ASC) was assembled with MnCo2O4 as the cathode and activated carbon (AC) as the anode to evaluate the potential for practical application. The MnCo2O4-discs//AC ASC exhibited an energy density (Ed) of 35.8 W h kg-1 at a power density (Pd) of 927.5 W kg-1. For the MnCo2O4-rings//AC ASC, an inferior Ed of 31.4 W h kg-1 under 890.9 W kg-1 was achieved. Furthermore, the two ASCs presented outstanding cyclic performance after 5000 cycles at 6 A/g. The exceptional properties of MnCo2O4 microstructures can be applied to the assembly of ASC devices, which can have promising potential for application in electrochemical energy storage. This synthetic method is straightforward, cost-effective, and can be extended to fabricate similar electrode materials with superior electrochemical performance.