Approaching capacity limit: A comprehensive structural and electrochemical study of capacity enhancement in Co3O4 nanoparticles

Abstract

Metal oxides are considered promising candidates for supercapacitor applications. Cobalt oxide (Co₃O₄) with its high theoretical capacitance (3650 Fg⁻¹) has garnered significant research interest in this context. However, achieving this high theoretical specific capacitance experimentally is still a challenge due to various factors. In the presented work, we have employed various complementary structural and electrochemical techniques for quantitative and qualitative analysis of the factors that result in performance degradation in Co₃O₄ nanostructure electrode. Our nominated Co₃O₄ electrode, with its superior nanostructure design has achieved an impressive experimental specific capacitance of 1685 Fg⁻¹ in 2 M NaOH electrolyte at 5 mV/s and has delivered an energy density of 84.25 Wh kg⁻¹ at a prominent power density of 356.8 W kg⁻¹. Moreover, 89 % of specific capacitance has been retained after 4000 cycle operations at 4 Ag⁻¹. This work amply establishes the importance of optimizing the identified factors for enhancing the kinetics of charge transportation in electrode and at solid/electrolyte interface, thereby bridging the gap between experimental and theoretical energy storage capacity of cobalt oxide-based materials.