Ni–Cu–Mn based hybrid supercapacitor with high flexibility and strength for wearable electronics

Abstract

Flexible supercapacitors are gaining huge attention as energy storage devices for wearable and portable electronics, owing to their lightweight nature, mechanical flexibility, high power output, and long operational lifespan. Their ability to maintain performance under bending and deformation makes them highly suitable for integration into next-generation flexible systems. However, flexible supercapacitor devices based on conventional polymers often struggle to maintain a balanced performance between flexibility and energy storage capability. Herein, we report the excellent performance of a NiCuMn oxide (NCM/O) based highly flexible hybrid supercapacitor (FHS). NCM/O powders were produced using a facile dealloying approach, resulting in a flaky nanoporous structure. The FHS showed a high areal capacitance of 414.6 mF cm⁻² at 1 mA cm⁻² and retained more than 75% of its capacitance even at a high current density of 6 mA cm⁻². The fabricated symmetric FHS demonstrated a notable energy density of 129.58 µWh cm⁻² at a power density of 750 µW cm⁻². It also exhibited outstanding long-term stability, retaining 94.7% of its initial capacitance after 10 000 charge–discharge cycles. Additionally, the device maintained stable electrochemical performance under various bending conditions, confirming its mechanical flexibility. Owing to these promising results, the in-house developed large flexible supercapacitor was used as a wristwatch strap, where it functioned reliably for several consecutive days.