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.