High energy density all-solid-state aqueous supercapattery: synergic effect of CuO nanosheets and polymer gel-electrolyte

Supercapatteries are hybrid energy storage devices that combine the high energy density of battery-type materials with the fast charge-discharge capability and high-power density of supercapacitors, making them promising power sources for implantable medical devices. In this study, battery-type CuO nanosheets were synthesized via two distinct routes‒traditional co-precipitation and rapid co-precipitation. In this study, battery-type CuO nanosheets were synthesized via two distinct routes‒ traditional co-precipitation and rapid co-precipitation. The crystal structure, morphology, and the electrochemical properties of CuO synthesized through two different techniques and at different time periods are systematically compared. In-vitro cytotoxic studies conducted on the best performing samples confirmed excellent biocompatibility. The CuO nanosheets obtained from traditional co-precipitation (CuO24h_TP) was tested in three-electrode configuration using 1M KOH electrolyte, delivering a remarkable specific capacity of 780 mAh g -1 at 4 A g -1 current density. To fabricate a complete biocompatible supercapattery Na 2 SO 4 /CMC gel electrolyte is employed which operates at a wide potential window of 3V. The assembled biocompatible supercapattery achieves a specific capacity of 46.7 mA h g -1 with an ultra-high energy density of 140.2 W h kg -1 at 3 kW kg -1 power density. Moreover, the supercapattery retained 91% of its capacitance even after 10,000 charge-discharge cycles, confirming its long-term stability. Therefore, the fabricated supercapattery with aqueous gel-electrolyte yields a high performance, biocompatible power source, for next-generation sustainable and biomedical energy storage devices.