Enabling plateau-dominated sodium storage in dual-doped hard carbon via industrial-scale engineering

Abstract

Hard carbon (HC) has emerged as a key anode for sodium-ion batteries (SIBs) due to its unique microcrystalline graphite regions and nanocavity structures. However, its relatively low plateau reversible capacity limits the energy density of SIBs. While conventional heteroatom doping can improve capacity, it often leads to low initial coulombic efficiency (ICE) and shifts the high capacity to the slope region. To overcome this, we develop a novel industrial-level heteroatom dual-doped strategy. By optimizing the dual-doped structure, we significantly enhance the Na+ ions adsorption and migration in the plateau region, leading to high reversible capacity (394 mAh/g) and high ICE (89%). We further reveal a coupled sodium storage mechanism during plateau sodiation. This mechanism involves both pore filling and interlayer embedding. The coexistence of these two processes explains the improved plateau capacity. The kilogram-scale HC shows stable performance over a wide temperature range in cylindrical full cells. Life cycle assessment shows a lower environmental impact than conventional graphite. Techno-economic analysis confirms competitive cost and good economic potential. This work provides a practical route toward high-energy, sustainable, and cost-effective SIBs for wide-temperature applications.