Polymer matrix-assisted commercial-level mass loading of porous cobalt manganese nitride towards high-performance binder-free electrodes for hybrid supercapacitors

Abstract

Supercapacitors (SCs) have a long lifespan and a fast rate of charging and discharging, making them a viable option for the energy source system of the future. However, the primary obstacle for the commercialization of SCs is the large discrepancy between lab-scale research and commercial-scale requirement. In this regard, the present work focuses on the synthesis of a customized high mass-loaded electrode without compromising electrochemical properties, i.e., a binder-free electrode with commercial-level mass-loaded porous cobalt manganese nitride via the assistance of a polyvinylpyrrolidone (PVP) matrix. The various weight percentages of PVP are studied in the growth solution to obtain the porous structure. A mass loading of 16 mg cm⁻² is obtained for the optimized PCMN electrode. The electrode exhibits excellent electrochemical properties with an areal capacitance of 12 764 mF cm⁻² at 4 mA cm⁻² and a cycling stability of 86% of the initial capacitance and a coulombic efficiency of 89% over 10 000 galvanostatic charge–discharge (GCD) cycles. Next, the electrochemical properties of tellurium-coated bio-carbon derived from radish synthesized via pyrolysis are investigated. A polyvinyl alcohol-potassium hydroxide gel electrolyte-assisted quasi-solid-state hybrid SC (QHSC) device using the above-prepared electrodes is fabricated. The QHSC device demonstrates excellent power and energy densities of 18 mW cm⁻² and 0.32 mW h cm⁻², respectively, with significant capacitance retention and coulombic efficiency of 89% and 98%, respectively, over 10 000 GCD cycles. The fabricated device is attached to a solar panel-integrated helmet for powering various electronic gadgets in real-life applications.