2D ultrathin basic cobalt carbonate nanosheets grown on nickel foam as high-performance electrode materials for asymmetric supercapacitors

[Display omitted] •2D ultrathin basic cobalt carbonate nanosheets were successfully fabricated;•The obtained product exhibited an ultrahigh areal capacitance of 4.7 F/cm2;•The corresponding asymmetric supercapacitor exhibited a high energy density;•The obtained sample could be a promising candidate for supercapacitors. In this work, high density 2D ultrathin basic cobalt carbonate nanosheets supported by Ni foam(NF) had been successfully fabricated via a one-step hydrothermal route. Owing to the presence of ultrathin 2D structure and opening channels among nanosheets were beneficial to increase the electron transmission rate and the ion diffusion rate, the resulted basic cobalt carbonate based electrode expressed an ultrahigh areal capacitance of 4.7 F/cm2 at 6 mA/cm2 and a good capacitance retention of 91 % even after 5000 cycles, which was superior than those of previously reported basic cobalt carbonate based materials. Besides, the corresponding asymmetric supercapacitor was assembled and exhibited a high energy density of 0.68 mWh/cm2 at a power density of 4.23 mW/cm2. It can be anticipated that the obtained 2D ultrathin basic cobalt carbonate nanosheets could be a promising candidate for high-performance supercapacitors.