Porous NixCo2-x(OH)3Cl nanoparticles as cathode materials for hybrid supercapacitor

•NixCo2-x(OH)3Cl nanoparticles were synthesized in the urea/choline chloride DES solution.•Porous NiXCo2-x(OH)3Cl nanoparticles have large specific surface area of 67.9 m2g − 1.•Ni0.5Co1.5(OH)3Cl // AC provides power density (17 kW kg−1) with energy density (50 Wh kg−1). Nanostructures are widely used in energy storage because they can effectively shorten ion transport distance and increase the density of active site. In this paper, the porous NixCo2-x(OH)3Cl nanoparticles were successfully synthesized by one step deep eutectic solvent assisted coprecipitation method with sodium dodecyl sulfate as a template. The NixCo2-x(OH)3Cl nanoparticles with optimal Ni/Co ratio exhibit superior electron transfer dynamics. Further, constructing porous hollow structure enables shortening the length of ion conveying between the electrolyte and NixCo2-x(OH)3Cl materials. The electrochemical properties of Ni0.5Co1.5(OH)3Cl electrode were superior in LiOH electrolyte compared with in NaOH and KOH solution. The Ni0.5Co1.5(OH)3Cl electrode shows high specific capacity that reaches 1351.8 F g − 1 at the current density of 1 A g − 1 and 876.6 F g − 1 at 20 A g − 1. In addition, it exhibits the 64% capacity reservation ratio after 5000 cycles at 5 A g − 1. Furthermore, an aqueous hybrid capacitor, assembled with the porous NixCo2-x(OH)3Cl nanoparticles as the cathode, delivers high energy density and power density (50.62 Wh kg−1 at 850 W kg−1), and retention rate of the capacitor is 75.3% after 10,000 cycles. The unique structure and excellent electrochemical properties reveal much potential for application in electronic devices. [Display omitted]