Biowaste assisted preparation of self-nitrogen-doped nanoflakes carbon framework for highly efficient solid-state supercapacitor application

Porous carbon materials synthesized from renewable and biowaste resources are receiving a lot of interest due to their various applications, economic benefit, and proper waste management. Recently, a variety of biological precursors have been utilized to create self-heteroatom-doped carbon materials. Mangifera indica is known as one of the world's most significant tropical fresh fruits in total global production. Peels are a by-product and account for around 20 % of the total fruit weight whose removal has become a major issue. In this study, the selfheteroatom-doped porous carbon (H-PC) skeleton has been synthesized using simple KOH activation and pyrolysis process. Different characterizations are applied to evaluate the effects of temperatures and stoichiometric amounts of KOH on the morphology, pore structure, and content of heteroatom in carbon skeleton. Moreover, it shows a maximum specific capacitance (Csp) of 402 F g-1 with 1 A g-1 in acidic electrolytes and also it works in neutral electrolytes. The fabricated solid-state symmetric supercapacitor (SS-SC) device demonstrates excellent durability up to 10,000 cycles with the highest energy density (47 Wh kg-1) and a power density (14.3 kW kg-1) even in acidic electrolytes. This study shows new relationships between environmental improvement by waste management, biowaste conversion, and proper use of renewable energy.