Design of aloe vera-shaped spinel copper cobalt sulfide nanostructures for advanced asymmetric supercapacitor applications

Recent advances in ternary metal sulfide nanostructures have highlighted their immense potential for outstanding-performance energy storage, due to their tunable morphologies, narrow bandgaps, and superior redox activity. Among these, CuCo₂S₄ has emerged as a promising candidate; however, its practical application has been hindered by limitations in structural stability and electrochemical efficiency. Herein, we report a facile synthesis of CuCo₂S₄ nanoparticles featuring a unique aloe vera-like architecture, engineered to enhance charge transport and active site accessibility. The obtained CuCo₂S₄ nanoparticles delivers a remarkable specific capacitance of 864.4 F g⁻¹ and maintains 89% capacitance retention over 5000 cycles, underscoring its prolonged cyclic stability. To evaluate its practical applicability, an solid-state electrochemical capacitor with an asymmetric design was assembled, achieving a high specific capacitance of 48.4 F g⁻¹, an energy density of 66.1 Whkg⁻¹, and a power density of 1445 W kg⁻¹, with 94% retention after 10,000 cycles. The enhanced electrochemical performance is associated to cobalt-induced surface activation and the introduction of oxygen vacancies, along with the synergistic effects of copper and cobalt within a highly accessible nanostructured framework. This work not only establishes aloe vera-inspired CuCo₂S₄ nanostructures as efficient electrodes for advanced supercapacitors but also opens new avenues for bio-inspired materials design in next-generation energy storage technologies.