P2-Na2/3MnO2 by Co Incorporation: As a Cathode Material of High Capacity and Long Cycle Life for Sodium-Ion Batteries
P2-Na2/3MnO2 by Co Incorporation: As a Cathode Material of High Capacity and Long Cycle Life for Sodium-Ion Batteries
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DOI：
10.1021/acsami.9b09317
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发表时间：
2019-08-14
影响因子：
9.5
通讯作者：
Myung, Seung-Taek
中科院分区：
文献类型：
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作者：
Konarov, Aishuak;Kim, Hee Jae;Myung, Seung-Taek
P2-Na 2/3 MnO 2化合物由于其高的初始容量和自然界中丰富的Na和Mn元素而成为钠离子电池的有吸引力的阴极之一。然而，Mn 3 + Jahn-Teller离子的存在阻碍了电极的长期性能。在此，我们挑战通过在P2-Na-2/3[Mn 1-xCox]O-2（x = 0-0.3）中用Co 3+取代Mn 3+来最小化由Mn 3+在结构中引起的Jahn-Teller畸变的影响。P2-Na-2/3[Mn 0.8Co 0.2]O-2化合物证实了其电化学性能，其容量为约175 mAh g（-1）（26 mA g（-1）），并且在0.1 C（26 mA g（-1））和10 C（2.6 A g（-1））下300次循环保持其初始容量的90%以上。操作性X射线衍射研究表明，单相反应与钠离子插入到结构中有关，伴随着约3%的小体积变化。此外，非原位X射线衍射和高分辨率透射电子显微镜的结果表明，在300个连续循环后，晶体结构保持不变。据信，这种良好的电极性能归因于晶体结构中存在的Co 3+所辅助的结构稳定。我们的发现提供了一种利用低成本的钠离子电池正极材料的方法。
The P2-Na2/3MnO2 compound is one of the attractive cathodes for sodium-ion batteries due to its high initial capacity and abundance of Na and Mn elements in nature. The existence of Mn3+ Jahn-Teller ion, however, impedes electrode performance for long term. Here, we challenge to minimize the effect of the Jahn-Teller distortion caused by Mn3+ in the structure, via substitution of Mn3+ by Co3+ in P2-Na-2/3[Mn1-xCox]O-2 (x = 0-0.3). The P2-Na-2/3[Mn0.8Co0.2]O-2 compound substantializes the electrochemical performance with a capacity of about 175 mAh g(-1) (26 mA g(-1)) and retained over 90% of its initial capacity for 300 cycles at 0.1 C (26 mA g(-1)) and 10 C (2.6 A g(-1)). The operando X-ray diffraction study indicates that a single-phase reaction is associated with the insertion of sodium ions into the structure, accompanied by a small volume change of approximately 3%. Furthermore, ex situ X-ray diffraction and high-resolution transmission electron microscopy results show that the crystal structure remained after 300 continuous cycles. It is believed that such good electrode performances attribute to the structural stabilization assisted by the presence of Co3+ in the crystal structure. Our finding provides a way to take advantage of low-cost Mn-rich cathode materials for sodium-ion batteries.