Synthesis and characterization of MnCo₂O₄ cuboidal microcrystals as a high performance psuedocapacitor electrode

Manganese cobaltite (MnCo₂O₄) is currently under screening as a high performance supercapacitor electrode owing to its high theoretical capacitance, improved electrical conductivity and long term cyclic stability. Herein, we report synthesis of MnCo₂O₄ cuboidal microcrystals using hydrothermal method and compare its performance with its flakes prepared by solid combustion process. Crystal structure, surface properties, and electrochemical properties of the flakes are studied using X-ray diffraction, gas adsorption, field emission scanning electron microscopy, cyclic voltammetry, galvanostatic charge–discharge cycling, and electrochemical impedance spectroscopy. The electrochemical properties of MnCo₂O₄ flakes synthesized using hydrothermal synthesis are superior to that synthesized using the solid combustion process. Electrochemical properties of the cuboidal microcrystals (∼specific capacitance, C_S ∼600 F g⁻¹ @ 0.5 A g⁻¹) are superior to those synthesized by the combustion process (C_S ∼128 F g⁻¹) due to improved faradic utilization of active surface area, layered cuboidal morphology, faster OH⁻ ion penetration owing to higher diffusion coefficient, and larger voltage range available for electrochemical reaction. - Highlights: • MnCo₂O₄ cuboidal microcrystals synthesized for the first time using hydrothermal synthesis. • Properties of the microcrystal is compared with combustion synthesized MnCo₂O₄ nanoflakes. • The microcrystals have 5 × higher surface area and wider pores than the flakes. • The microcrystals have 4 × higher capacitance than the nanoflakes. • ∼126% of capacitance retention after 3000 cycles.