Enhancing energy density in planar micro-supercapacitors: The role of few-layer graphite /carbon black/NiCo₂O₄ composite materials

The advancement of planar micro-supercapacitors (PMSCs) for micro-electromechanical systems (MEMS) has been significantly hindered by the challenge of achieving high energy and power densities. This study addresses this issue by leveraging screen-printing technology to fabricate high-performance PMSCs using innovative composite ink. The ink, a synergistic blend of few-layer graphene (Gt), carbon black (CB), and NiCo₂O₄, was meticulously mixed to form a conductive and robust coating that enhanced the capacitive performance of the PMSCs. The optimized ink formulation and printing process result in a micro-supercapacitor with an exceptional areal capacitance of 18.95 mF/cm² and an areal energy density of 2.63 µWh/cm² at a current density of 0.05 mA/cm², along with an areal power density of 0.025 mW/cm². The devices demonstrated impressive durability with a capacitance retention rate of 94.7% after a stringent 20000-cycle test, demonstrating their potential for long-term applications. Moreover, the PMSCs displayed excellent mechanical flexibility, with a capacitance decrease of only 3.43% after 5000 bending cycles, highlighting their suitability for flexible electronic devices. The ease of integrating these PMSCs into series and parallel configurations for customized power further underscores their practicality for integrated power supply solutions in various technologies.