Co2(OH)3Cl nanoparticles as new-type electrode material with high electrochemical performance for application in supercapacitor

In this work, we report the preparation of Co 2 (OH) 3 Cl nanoparticles with average size of ∼20   nm and well-defined cubic shape at room temperature by an epoxide precipitation route. It was found that the as-prepared Co 2 (OH) 3 Cl nanoparticles could be used as a promising new electrode material for application in redox supercapacitors due to its high electrochemical performance. It presented superior specific capacitance of 783   F   g −1 at low current density of 2.8   A   g −1 , while it had a high value of 604   F   g −1 at high current density of 56.6   A   g −1 , proving its excellent high rate performance. Its 75% capacitance retention after 10,000 cycles of charge–discharge demonstrated its long-life span. According to characterization results, the possible mechanism for the electrochemical process that Co 2 (OH) 3 Cl nanoparticles underwent was proposed as a process of Co 2 (OH) 3 Cl   →   β-Co(OH) 2   →   CoOOH   ↔   Co 3 O 4 .