Scalable complete conversion of MgCo2O4 by mechanochemistry for high-performance supercapacitors

Abstract

MgCo2O4, a cobalt-based binary oxide, has garnered increasing attention as a promising active material for supercapacitor electrodes due to its enhanced conductivity and high theoretical capacitance. In this study, a novel mechanochemistry approach was developed to convert stoichiometric MgO and Co2O3 into MgCo2O4. This innovative synthesis involved a one-step ball milling process that integrates two reaction steps. Initially, MgO reacted with water to form Mg(OH)2, followed by migration of Mg ions from Mg(OH)2 into Co2O3 lattice to generate MgCo2O4. The milling parameters were optimized to enhance the conversion efficiency of MgCo2O4 through X-ray Diffraction analysis. Complete conversion of MgCo2O4 was achieved with a single batch production capacity of 100 g, using a ratio of water volume to reactant weight of 2.0 mL/g, a ball-to-powder ratio of 10:1, a revolution speed of 350 rpm, and a milling time of 80 hours. The synthesis mechanism was elucidated using X-ray Photoelectron Spectroscopy. The synthesized MgCo2O4 particles exhibited a small particle size of 117.8 nm and a high specific surface area of 63.3 m²/g, based on these properties, the electrode exhibited a notable specific capacitance of 665.8 F/g at 0.1 A/g, highlighting its potential as an excellent active material for supercapacitor electrodes. This study demonstrates a facile, green, cost-effective, and scalable production method for MgCo2O4, promoting its application in electrochemical energy storage.