Recycling waste tires as an economical carbon source for developing high-value hard carbon anodes for potassium/sodium-ion batteries

The large-scale improper disposal of organic solid waste poses significant environmental challenges. Converting this waste into high-value carbon-based materials provides a sustainable solution for energy applications. In this study, we propose the development of a nitrogen/oxygen-enriched hard carbon material derived from low-cost, environmentally detrimental waste tires through a two-step pre-oxidation and nitriding process. The resulting material exhibits exceptional electrochemical performance as an anode in potassium-ion batteries (PIBs) and sodium-ion batteries (SIBs). In PIBs, it achieves a high reversible capacity of 363 mAh g- 1 after 200 cycles at 100 mA g- 1 and demonstrates excellent cycling stability, maintaining 328.9 mAh g- 1 after 1000 cycles at 1000 mA g- 1. In SIBs, it maintains a discharge capacity of 406.7 mAh g- 1 after 100 cycles at a high current density of 1000 mA g- 1. The material's outstanding performance is attributed to its high surface area and abundant heteroatom doping, which create numerous active sites for potassium and sodium ion storage, enhancing rapid ion transport and electron flow. This work presents a simple, environmentally friendly, and sustainable approach to upcycling waste tires into high-performance hard carbon materials, offering a promising anode solution for advanced PIBs/SIBs.