The Role of Sodium in LiNi0.8Co0.15Al0.05O2 Cathode Material and Its Electrochemical Behaviors

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• 作者：Hongbin Xie ; Ke Du ; Guorong Hu ; Zhongdong Peng ; Yanbing Cao
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：February 18, 2016
• 年：2016
• 卷：120
• 期：6
• 页码：3235-3241
• 全文大小：551K
• ISSN：1932-7455

文摘

Sodium is first introduced to modify Ni-rich LiNi_0.8Co_0.15Al_0.05O₂ cathode material in this work, and Li_1–xNa_xNi_0.8Co_0.15Al_0.05O₂ (x = 0, 0.01, 0.02, 0.05) is successfully synthesized by using Na₂CO₃ as sodium resource through coprecipitation and solid state calcination route. The morphology of the samples analyzed with SEM, EDS. and TEM show that all the samples maintain sphere-like morphology and the main elements are uniformly distributed. X-ray diffraction (XRD) results show that all the synthesized materials have typical hexagonal structure without impurities. The lattice parameters calculated from the XRD data are also refined by Rietveld refinement methods, confirming that the position of Na in the NCA is occupying the Li slab as designed. Despite a slight decrease in the initial discharge capacities, the sodium doped materials display improved capacity retention as well as superior performance at high rates. The Li_0.99Na_0.01Ni_0.8Co_0.15Al_0.05O₂ exhibits an initial discharge specific capacity of 184.6 mAh g^–1 at 0.1 C and a capacity retention of 90.71% after 200 cycles when cycled at 1 C between 2.8 and 4.3 V, which is greatly superior to the pristine one, owing to the enlarged Li layer spacing, decreased Li⁺ migration activation energy, the low cation mixing, and enhanced structural stability brought by sodium treatment.