Design and synthesis of dendritic Co3O4@Co2(CO3)(OH)2 nanoarrays on carbon cloth for high-performance supercapacitors

Cobalt carbonate hydroxide possesses interesting capacitive properties due to the unique crystal structure. Herein, the hierarchical Co3O4@Co2(CO3)(OH)2 dendritic structure was fabricated on carbon cloth with Co3O4 nanoneedles as the inner core to enhance the conductivity. The loading efficiency of Co2(CO3)(OH)2 nanowhiskers had improved obviously, and the nanowires provided more electrochemical sites to facilitate the superior electrochemical energy storage capacity of supercapacitor. The dendritic electrode with the core–shell structure had a high area-specific capacitance (1541 mF cm−2 at 1 mA cm−2), good rate capacitance (only 18.1% specific capacitance lost when the current density increased to 5 mA cm−2), as well as better electrochemical cycle stability (a capacitance retention of 72.1% after 5000 cycles at a high current density of 5 mA cm−2). The dendritic Co3O4@Co2(CO3)(OH)2 and activated carbon as cathode and anode, respectively, were used to assemble an asymmetric supercapacitor, possessing the better area-specific capacitance of 87 mF cm−2 as well as well-deserved longevity retaining approximately 97.3% of initial capacitance even after 10,000 cycles at 1 mA cm−2. The excellent properties stemmed from electro-active sites galore, strong adhesion between the core and shell, superior conductivity, as well as excellent ion transfer. The novel materials and feasible strategy are promising for next-generation hybrid supercapacitor with high performance.