Fast and reversible redox reaction of MgCo₂O₄ nanoneedles on porous β-polytype silicon carbide as high performance electrodes for electrochemical supercapacitors

MgCo₂O₄ nanoneedles were deposited onto micro and mesoporous silicon carbide flakes (SiCF) to synthesize hybrid electrode materials with high capacitive performance for use as supercapacitors. These SiCF/MgCo₂O₄ electrodes were fabricated at different MgCo₂O₄ feeding ratios to determine the optimal MgCo₂O₄ amount for both total surface area coverage and a suitable redox reaction rate by maximizing the synergy between the electric double layer capacitive effects of SiCF and the Faradic reaction of MgCo₂O₄ nanoneedles. The SiCF/MgCo₂O₄ electrode formed at a MgCo₂O₄/SiCF feeding ratio of 1.8:1 (SiCF/MgCo₂O₄(1.8)) had a specific surface area of 1069 m² g⁻¹. This surface featured the highest specific stored charge capacity of 310.02 C g^-1 at a scan rate of 5 mV s^-1 with 83.2% rate performance when the scan rate was increased from 5 to 500 mV s^-1 in a 1 M KOH electrolyte. The outstanding electrochemical performance of the SiCF/MgCo₂O₄(1.8) electrode can be attributed to the ideal electrode material design, considering both the electric double-layer capacitive contribution of SiCF and the battery-type electrochemical behavior of the MgCo₂O₄ nanoneedles on the SiCF surface. For high capacity electrode materials, this hybrid material strategy introduces possibilities for combinations of porous silicon carbide with other battery-type binary metal oxide materials.