阴极
材料科学
溶解
化学工程
结构精修
中子衍射
容量损失
氧化物
电化学
化学
结晶学
电极
冶金
晶体结构
工程类
物理化学
作者
Muhammad Mominur Rahman,Jing Mao,Wang Hay Kan,Chengjun Sun,Luxi Li,Yan Zhang,Maxim Avdeev,Xi‐Wen Du,Feng Lin
出处
期刊:ACS materials letters
[American Chemical Society]
日期:2019-10-16
卷期号:1 (5): 573-581
被引量:35
标识
DOI:10.1021/acsmaterialslett.9b00347
摘要
Developing stable cathode materials represents a crucial step toward long-life sodium-ion batteries. P2-type layered oxides are important as cathodes for their reversibility, but their long-term performance in full cells remains a key challenge. Herein, we report Na0.75Co0.125Cu0.125Fe0.125Ni0.125Mn0.5O2 with an intergrowth of ordered P2 and P3 phases, studied by neutron diffraction and Rietveld refinement. A stable electrochemical performance is achieved in Na half cells with 100% capacity retention at a rate of C/10 after 100 cycles (initial capacity of 90 mAh/g), 96% capacity retention at a rate of 1 C after 500 cycles (initial capacity of 70 mAh/g), and 85% capacity retention at a rate of 5 C after 1000 cycles (initial capacity of 55 mAh/g). Stable full cell performance is achieved with 84.2% capacity retention after 1000 cycles at a rate of 1 C. Synchrotron X-ray diffraction, spectroscopy, and imaging are applied to elucidate the relationship between chemical/structural evolution and battery performance. A reversible local and global structural evolution is observed during initial cycles. Meanwhile, the challenges with enabling prolonged cycling (beyond 1000 cycles) may be associated with Fe dissolution and formation of a copper oxide phase. This study implies that cathodes with complex chemical and structural formations may stabilize electrochemical performance and highlights the importance of decoupling the contribution of each transition metal to performance degradation.
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