Controlled transformation of V-doped Co(OH)2 hexagonal nanosheets towards enhanced electrochemical performance

Abstract

To meet the energy demands, development of efficient electrode materials or structures for electrochemical energy storage systems are highly desired. Hence, novel hexagonal nanosheets of vanadium doped Co(OH)2 have been synthesized by cost effective hydrothermal-method, which exhibited excellent electrochemical performance. The structural characterizations were performed by XRD, FESEM, EDS and TEM tools, which confirmed the phases purity and perfect hexagonal based nanosheets. It was also revealed that with the increase in doping concentration of vanadium, the morphology was gradually transformed from hierarchical structures to hexagonal nanosheets. CV results exhibited that the specific capacitance was increased on vanadium doping and maximum capacitance of 1357 F/g was obtained for 15% V-doped Co(OH)2 sample, which is almost two times greater than undoped-Co(OH)2. Furthermore, this sample has shown a very high capacitance retention of 89% over 3000 CV cycles. These improvements are attributed to the optimized hexagonal nanosheets based morphology and appropriate doping value of redox active element i.e. vanadium into Co(OH)2. This V-doping affected the shape of nano structures along with changes in redox reactions of Co(OH)2.