Li Weiyi, He Bijiao, Zhang Fang, Xin Yan, Cai Shen, Tian Huajun
Beijing Laboratory of New Energy Storage Technology and Key Laboratory of Power Station Energy Transfer Conversion and System of Ministry of Education, School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing, 102206, China.
Small. 2025 May;21(19):e2500271. doi: 10.1002/smll.202500271. Epub 2025 Mar 25.
NaFe(SO) (NFSO) is a promising cathode material for sodium-ion batteries (SIBs) due to its low cost and high operating potential (≈3.8 V). However, poor intrinsic electronic conductivity and sluggish kinetics are major drawbacks to its practical application. Herein, magnesium doped NaFe(SO) microspheres (Na(FeMg)(SO)) are synthesized via a designed spray-drying process. The optimized cathode material (NFSO@C-Mg0.02) possesses excellent rate performance up to 50C (50.8 mAh g at 50C) and long-cycle stability (capacity retention of 78.3% even after 9000 cycles at 10C). Despite an increase in the mass loading to 10 mg cm, the electrode continues to represent a reversible capacity of 72.1 mAh g at 3C. Furthermore, NFSO@C-Mg0.02║HC full cell demonstrates superior cycling stability (80% capacity retention over 8000 cycles at 5C) and high energy density (≈310 Wh kg, based on the cathode). In situ X-ray diffraction (XRD) results reveal that the Mg doping strategy successfully mitigates the variation in lattice volume. The density functional theory (DFT) calculations verify that the prominent rate performance is attributed to the enhanced Na diffusion kinetics and low ionic-migration energy barrier. This work provides an effective strategy and a fundamental understanding to enhance the electrochemical performance of cathode materials for SIBs.
NaFe(SO)（NFSO）由于其低成本和高工作电位（约3.8 V），是一种很有前景的钠离子电池（SIBs）正极材料。然而，其固有的电子导电性差和动力学迟缓是其实际应用的主要缺点。在此，通过设计的喷雾干燥工艺合成了镁掺杂的NaFe(SO)微球（Na(FeMg)(SO)）。优化后的正极材料（NFSO@C-Mg0.02）具有高达50C的优异倍率性能（50C时为50.8 mAh g）和长循环稳定性（即使在10C下循环9000次后容量保持率仍为78.3%）。尽管质量负载增加到10 mg cm，但该电极在3C时仍具有72.1 mAh g的可逆容量。此外，NFSO@C-Mg0.02║HC全电池表现出优异的循环稳定性（5C下8000次循环后容量保持率为80%）和高能量密度（基于正极约为310 Wh kg）。原位X射线衍射（XRD）结果表明，镁掺杂策略成功减轻了晶格体积的变化。密度泛函理论（DFT）计算证实，优异的倍率性能归因于增强的Na扩散动力学和低离子迁移能垒。这项工作为提高SIBs正极材料的电化学性能提供了一种有效策略和基本认识。
