Delicate preparation of in-situ biochar zirconium dioxide using the one-step method of repairing tailings with Pennisetum Hydridum: electrode study of symmetrical (snap-on) supercapacitor.

Utilizing plant-derived electrode materials with natural multi-channel structure for supercapacitors is an effective approach for developing sustainable energy and innovatively utilizing agricultural waste. In this study, based on the green synthesis strategy of recycling waste resources, Pennisetum Hydridum loaded zirconium dioxide composite electrode materials were prepared by low-temperature annealing under argon protection using the natively grown Pennisetum Hydridum in rare earth tailings as precursors. The process accomplished the recovery of carbon resources while realizing the ecological restoration of tailings. It was found that the 800 °C annealing condition not only optimized the crystallinity of zirconium dioxide, but also its mild heat treatment parameters significantly reduced the carbon footprint of the process. At a current density of 1 A/g, this material exhibited an excellent specific capacitance of 152 F/g, which was 2.85 times higher than that of graphene loaded zirconium dioxide. After 5000 cycles, the capacity retention rate reached 88 %, demonstrating its long-term cycling stability. This enabled effective extension of equipment lifespan and reduced resource consumption caused by electrode material replacement. The symmetric energy storage device constructed based on this material had a cycle capacity retention rate as high as 91.3 % and maintained a coulombic efficiency of 100 %, providing a theoretical basis for the technical paradigm of coordinated development of mine area ecological restoration and low-carbon energy storage. By integrating the elements of biomass carbon sequestration, waste recycling and low-temperature clean preparation, this study demonstrated a new way of thinking for the design of carbon neutral target functional materials.