Chlorine-doped carbonated cobalt hydroxide for supercapacitors with enormously high pseudocapacitive performance and energy density

Development of supercapacitors which exhibit high energy density without much compromise on power density is a great challenge. Although the pseudocapacitors are very promising in this regard but only surface redox reactions are not sufficient to solve future energy demands. Thus the involvement of the entire electrode materials in Faradaic redox reaction is necessary for excellent results. Here, we have synthesized well-defined and self-stabilized chlorine-doped carbonated cobalt hydroxide (Co(CO₃)_0.35Cl_0.20(OH)_1.10) nanowires (NWs) composed of discrete particles (which allow the involvment of entire NW) via a facile hydothermal method for supercapacitors to introduce the concept of deep Faradaic redox reaction. The engineered structure and unique composition along with define porosity, existence of structure stabilizer counter anions and hydrophilic nature of NWs allow deep diffusion of electrolyte ions. The NWs have shown extraordinary capacitance (9893.75F/g at 0.5A/g) and excellent energy density (220Wh/kg) along with high rate capability and stability for 10,000 cycles. We believe that higher energy density devices can be developed using our concept of deep Faradaic redox reactions which will help the practical realization of supercapacitors.