The incorporation of cobalt ions into hydroxyapatite nanostructure for a novel range of electrochemical energy storage applications.

Supercapacitors (SCs) have garnered extensive attention for their notable advantages, including extended cycle life, high energy density, and cost-effectiveness. Due to their large energy storage capacity and high output power, the development of pseudocapacitive materials for energy-oriented applications has been of great importance. The integration of nanoscale active materials in batteries results in faster redox kinetics. Consequently, alters the material's electrochemical characteristics from battery-like to pseudocapacitive-like behavior driven by enhanced surface area and reduced diffusion routes. This study aims to investigate the efficacy of pure hydroxyapatite and Co2+-doped hydroxyapatite (HAP) nanoparticles as electrode materials for SCs. The pure HAP and Co2+-doped HAP nanoparticles were synthesized via the Sol-Gel method. Electrochemical techniques such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were utilized to investigate the electrochemical behavior of the developed electrode. The highest values of specific capacitance (Csp) and energy density for the SC with Co2+-doped HAP nanoparticles electrode were obtained at 324 F g−1 and 145.8 Wh kg−1, respectively, at a current density of 1.2 A g−1. According to the data above, Co2+-doped HAP nanoparticles can be used as a substitute to improve electrochemical performance in energy storage applications. • Synthesis of pure HAP and Co2+-doped HAP nanoparticles via Sol-Gel method. • The max energy density 129.6 Wh kg−1 was obtained for SC with Co2+-doped HAP nanoparticles. • The cycling stability with a capacitance retention of 92.47 % after 5000 cycles for Co2+-doped HAP nanoparticles was obtained. [ABSTRACT FROM AUTHOR]