Modifier-assisted co-thermal carbonization of lignite for hard carbon with enriched pseudo-graphitic domains and closed pores toward enhanced sodium storage

作者：Huihui Zeng, Huiyang Sun, Baolin Xing, Xiahui Gui, Qin Xu, G.S. Huang, Chuanxiang Zhang, Yuanfeng Wu, Yichao Wang, Zhengfei Chen · 发表于：Carbon · 年份：2025 · DOI：10.1016/j.carbon.2025.120694 · 被引用次数：14 · 研究领域：Coal Properties and Utilization、Coal and Its By-products、Thermal and Kinetic Analysis

Lignite, characterized by disordered aromatic lamellae, natural pores and microfractures, and surface-active functional groups, has emerged as a high-quality precursor for advanced hard carbon anodes in sodium-ion batteries (SIBs). In this work, we propose a modifier-assisted co-thermal carbonization strategy to precisely tailor the pseudo-graphitic domains and closed pores in lignite-derived hard carbons (LHC), aiming to enhance their Na + storage capabilities. Through incorporating urea during carbonization, the resulting nitrogen-doped lignite-based hard carbon (N-LHC) possesses a high content of pseudo-graphitic domains (43.6%), an optimized interlayer distance (0.373 nm), and a greater number of closed pores interconnected by short-range ordered microcrystals. Benefiting from these structural and chemical modifications, the N-LHC anode delivers a high reversible capacity of 380 mAh·g -1 , with the plateau capacity of 207 mA·g -1 and an improved initial Coulombic efficiency (ICE) of 79.1%. When paired with a NaFe 1/3 Ni 1/3 Mn 1/3 O 2 cathode, the full-cell achieves a notable energy density of 240.8 Wh·kg -1 at 20 mA·g -1 and retains 157.5 Wh·kg -1 at 200 mA·g -1 with a power density of 230.7 W·kg -1 . Electrochemical kinetics combined with ex-situ X-ray diffraction analyses reveal a synergistic sodium storage mechanism involving adsorption, intercalation, and pore filling. DFT calculations further confirm the critical role of heteroatoms doping in enhancing Na + adsorpti...