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

Abstract

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 m(2) 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. (C) 2017 Elsevier B.V. All rights reserved.