Balancing Graphitic Nanodomains and Heteroatom Doping in Hard Carbons Toward High Capacity and Durable Potassium‐Ion Battery Anodes

Abstract Hard carbons (HCs) have emerged as promising candidates for commercial anodes in potassium‐ion batteries (PIBs). However, a thorny challenge remains in achieving high reversible capacities at high charge/discharge rates, which significantly hinders the development of HCs for PIBs. Here, a temperature‐controlled strategy is proposed to effectively balance graphitic nanodomains and heteroatom doping content in HCs, resulting in widened carbon layer spacing, high conductivity, and abundant K‐ion intercalation sites. The optimized NO‐HC₆₀₀ electrode exhibits a high reversible capacity of 315.0 mAh g⁻¹ at 0.2 A g⁻¹, and exceptional cyclic stability (235.0 mAh g⁻¹ after 1200 cycles at 2.0 A g⁻¹ with a capacity retention rate of 98.82%). Furthermore, systematic in /ex situ experiments unveil a highly reversible “adsorption–intercalation” mechanism governing potassium‐ion storage, confirming the origin of the superior performance. This work offers valuable insights into the facile preparation of HC anodes with high reversible capacity and fast charge/discharge capability for PIBs.