[Co(salen)] derived Co/Co3O4 nanoparticle@carbon matrix as high-performance electrode for energy storage applications

Abstract Cobalt/cobalt oxide nanoparticle-embedded in a carbon matrix was synthesized by one spot pyrolysis of cobalt salen complex [Co(salen)] at 800 °C in an argon atmosphere. The X-ray diffraction studies confirmed the presence of Co and Co 3 O 4 in the carbon matrix. The SEM and TEM observations showed the homogeneous distribution of the Co/Co 3 O 4 grains on the carbon matrix. Cyclic voltammograms and galvanostatic charge-discharge studies done on the CR2032 coin cell confirmed that the Co/Co 3 O 4 @carbon matrix was electrochemically active. A stable specific capacity as high as 1000 mA h g −1 has been observed over 50 charge-discharge cycles at C/5 rate. It is believed that the carbon matrix acted both as a spacer to accommodate volume changes during Li intercalation-deintercalation process and also as conductive network leading to the excellent electrochemical performance of the Co/Co 3 O 4 @carbon matrix. Further, supercapacitor studies revealed that a specific capacitance of 615 F g −1 at 1 A g −1  has been exhibited by the Co/Co 3 O 4 @carbon matrix electrode in 1 M KOH with high Coulombic efficiency (92%) as well as excellent cycling stability for 5000 cycles.