Sustainable synthesis of hierarchical nitrogen-doped porous carbons from polyolefin waste for high-performance supercapacitors

The recycling of widely used plastic wastes into high-valued carbon materials for electrochemical energy storage is promising but still challenging. In this study, we demonstrate a sustainable strategy for recycling polyolefin wastes into hierarchical nitrogen-doped porous carbon by utilizing the synergistic interaction between melamine and zinc chloride. The synergistic interaction not only facilitates the formation of thermally stable structure, achieving a high carbon yield (similar to 34.3 %) and a high nitrogen doping level (11.2 at.%), but also generates abundant meso-/micropores with a high specific surface area (1031.7 m(2)g(-1)). These merits endow the nitrogen-doped porous carbon electrode with an ultrahigh capacitance of 224.8 F g(-1) at 1 A g(-1) and 91.2 % retention after 50,000 cycles. Consequently, the assembled symmetrical supercapacitor exhibits a high energy density of 43.8 Wh kg(-1) at a power density of 750 W kg(-1) and outstanding electrochemical stability of similar to 87 % after 10,000 cycles in a TEABF(4)/AN electrolyte. In addition, the applicability of our strategy to other polyolefin-based plastic wastes such as polypropylene and polystyrene proves its versatility. Our study provides a promising approach for recycling polyolefin wastes into high-value products to alleviate environmental problems and opens a new horizon for the production of high-performance electrode materials for electrochemical energy storage.