Prussian blue analogue Co3(Co(CN)6)2 cuboids as an electrode material for high-performance supercapacitor

Prussian blue analogue Co3(Co(CN)6)2 (CoHCC) cuboids were directly synthesized on Ni-foam from a single cobalt source precursor via a facile solvothermal method, and the effect of annealing temperature on the physical and electrochemical properties were studied. CoHCC:Ni-foam annealed at 150 °C was free from zeolitic water content and exhibited a maximum specific capacity of 1118C g−1 at a current density of 1 A g−1 and an excellent cycling stability over 5000 cycles with 89% retention in capacity. It was found that the maximum specific capacity is a result of contributions from the capacitive contribution (originating from the electric double layer capacitance and pseudo capacitance) and diffusion capacitance (originating from insertion/desertion of K+ ions in the CoHCC framework). Moreover, an asymmetric supercapacitor constructed from CoHCC:Ni-foam and activated carbon delivered specific energies of 22.5 Whkg−1and 17 Whkg−1at the specific powers of 990 Wkg−1 and 2464 Wkg−1, respectively, and exhibited excellent cycling stability over 5000 cycles. The excellent electrochemical performance of CoHCC:Ni-foam electrodes suggests a promising future for practical applications.