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

Novel MnCo 2 O 4 -discs and MnCo 2 O 4 -rings were respectively prepared through a facile hydrothermal approach with a post annealing treatment. These MnCo 2 O 4 -discs exhibited battery-type electrochemical response with a high capacity of 296.1C/g at 1 A/g in 2 M of KOH electrolyte. The assembled MnCo 2 O 4 -discs//AC asymmetric supercapacitor delivered a high energy density of 35.8 W h kg−1 at the power density of 927.5 W kg−1. [Display omitted] • Novel MnCo 2 O 4 -discs were hydrothermally prepared with a post annealing treatment. • A high specific capacity of 296.1C/g at 1 A/g was delivered. • Just a little capacity decay over 5000 cycles at a high current density of 6 A/g. • The ASC device delivered an energy density of 35.8 W h kg−1 at 927.5 W kg−1. Herein, porous MnCo 2 O 4 with disc-like (MnCo 2 O 4 -discs) and ring-like (MnCo 2 O 4 -rings) microstructures were respectively synthesized using an initial hydrothermal method at different temperatures and a calcination treatment in air. The electrochemical properties of these MnCo 2 O 4 materials were investigated in three-electrode and two-electrode systems, and as such, MnCo 2 O 4 presented a battery-like electrochemical response. The specific capacity of MnCo 2 O 4 -discs was determined to be 296.1C/g at 1 A/g, superior to 246.3C/g for MnCo 2 O 4 -rings. An asymmetric supercapacitor (ASC) was assembled with MnCo 2 O 4 as the cathode and activated carbon (AC) as the anode to evaluate the potential for practical application. The MnCo 2 O 4 -discs//AC ASC exhibited an energy density (E d) of 35.8 W h kg−1 at a power density (P d) of 927.5 W kg−1. For the MnCo 2 O 4 -rings//AC ASC, an inferior E d 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 MnCo 2 O 4 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. [ABSTRACT FROM AUTHOR]