Sea-Urchin-Like Copper–Cobalt Carbonate Hydroxides for Solid-State Asymmetrical Supercapacitors

Supercapacitors, in particular, are gaining popularity in electronic devices, electric vehicles, and emergency power supplies due to their safe operation, rapid charge/discharge rates, high power density, and extended lifespan compared with batteries and fuel cells. However, to further enhance the energy density, widening the operating voltage window through the design of asymmetric supercapacitors and increasing the capacitance of electrode materials have been explored. This study focuses on the development of a sea-urchin-like morphology composed of bimetallic copper–cobalt carbonate hydroxides (CCCOHs) by using a hydrothermal method to optimize the surface morphology and improve energy storage capabilities. The synthesized CCCOH-24 sample demonstrated an impressive specific capacitance of 675 C g –1 at a current density of 15 A g –1 and maintained 87% stability at 30 A g –1 . When assembled into an asymmetric solid-state supercapacitor with activated carbon, the device achieved an energy density of 63 Wh kg –1 and a power density of 10.2 kW kg –1, retaining over 88% capacitance after 10000 cycles. This study highlights the potential of CCCOHs with tailored morphologies for advanced supercapacitor applications, offering a pathway to enhance the energy storage performance and stability.