N/O Dual-Doped Environment-Friendly Hard Carbon as Advanced Anode for Potassium-Ion Batteries

Potassium-ion batteries (PIBs) are considered as promising candidates for lithium-ion batteries due to the abundant reserve and lower cost of K resources. However, K⁺ exhibits a larger radius than that of Li⁺, which may impede the intercalation of K⁺ into the electrode, thus resulting in poor cycling stability of PIBs. Here, an N/O dual-doped hard carbon (NOHC) is constructed by carbonizing the renewable piths of sorghum stalks. As a PIB anode, NOHC presents a high reversible capacity (304.6 mAh g^-1 at 0.1 A g^-1 after 100 cycles) and superior cycling stability (189.5 mAh g^-1 at 1 A g^-1 after 5000 cycles). The impressive electrochemical performances can be ascribed to the super-stable porous structure, expanded interlayer space, and N/O dual-doping. More importantly, the NOHC can be prepared in large scale in a concise way, showing great potential for commercialization applications. This work may impel the development of low-cost and sustainable carbon-based materials for PIBs and other advanced energy storage devices.