Zhang Huiyu, Li Jian, Shen Tongyang, Liu Jian, Wu Tong, Feng Kewei, Huang Taomei, Tang Haoyu, Deng Chengming, Xiong Lizhi, Wu Xianwen, Xiang Yanhong
College of Physics and Electromechanical Engineering, Jishou University, Jishou, Hunan, 416000, China.
School of Pharmaceutical Sciences, Jishou University, Jishou, Hunan, 416000, China.
Small. 2025 Jun;21(22):e2411775. doi: 10.1002/smll.202411775. Epub 2025 May 2.
Sodium manganese oxide NaMnO has become a promising cathode material for sodium ion batteries due to its stable tunnel structure, but its low Na content and Mn induced Jahn Teller (JT) distortion pose challenges to its practical application. This study constructs a tunnel-layered hybrid material that combines the advantage of two structures through co-doping with Mg and Co ions. The Mg/Co co-substitution effect is crucial in regulating the hybrid crystal structure, as it compresses the TM-O layer (transition metal oxide plates) and expands the Na layer spacing, enhancing Na diffusion kinetics. This modification also mitigates lattice distortion from the JT effect, improving structural stability. Electrochemical studies reveal that the NaMnMgCoO cathode in sodium-ion batteries demonstrates a higher initial specific capacity (135.8 mAh g, 0.5C) and improved cycle stability. Density functional theory (DFT) calculations further confirm that Mg and Co ions reduce the band gap, enhance electronic conductivity, and improve rate performance. Additionally, the increased O 2p state density near the Fermi level favors oxygen redox reactions. This research provides a new method for the design of energy storage materials. Besides, the investigation into the mechanism of Mg and Co dual substitution offers a promising strategy for optimizing sodium-ion batteries.
钠锰氧化物NaMnO因其稳定的隧道结构而成为一种有前景的钠离子电池正极材料，但其低钠含量和锰诱导的 Jahn-Teller（JT）畸变对其实际应用构成了挑战。本研究通过镁离子和钴离子共掺杂构建了一种结合两种结构优势的隧道-层状混合材料。镁/钴共取代效应在调节混合晶体结构方面至关重要，因为它压缩了TM-O层（过渡金属氧化物板）并扩大了钠层间距，增强了钠扩散动力学。这种改性还减轻了JT效应引起的晶格畸变，提高了结构稳定性。电化学研究表明，钠离子电池中的NaMnMgCoO正极表现出更高的初始比容量（135.8 mAh g，0.5C）和改善的循环稳定性。密度泛函理论（DFT）计算进一步证实，镁离子和钴离子降低了带隙，提高了电子导电性，并改善了倍率性能。此外，费米能级附近增加的O 2p态密度有利于氧氧化还原反应。本研究为储能材料的设计提供了一种新方法。此外，对镁和钴双重取代机制的研究为优化钠离子电池提供了一种有前景的策略。
