Optimization of Layered Cathode Material with Full Concentration Gradient for Lithium-Ion Batteries

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• 作者：Jin-Wook Ju ; Eung-Ju Lee ; Chong S. Yoon ; Seung-Taek Myung ; Yang-Kook Sun
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：January 9, 2014
• 年：2014
• 卷：118
• 期：1
• 页码：175-182
• 全文大小：579K
• ISSN：1932-7455

文摘

Li[Ni_xCo_yMn_{1鈥?i>x鈥?i>y}]O₂ cathode materials were synthesized with varying concentration gradients of Ni and Co ions from the particle center (0.62鈥?.74 mol % for Ni and 0.05 mol % for Co) to the surface (0.48鈥?.62 mol % for Ni and 0.18 mol % for Co), i.e., full concentration gradient (FCG) with fixed Mn concentrations. In particular, the Mn concentration (20, 25, and 33 mol %) was controlled to optimize electrode performance. The average chemical compositions of lithiated products were Li[Ni_xCo_0.16Mn_0.84鈥?i>x]O₂ (x = 0.64, 0.59, 0.51). These cathode materials with concentration gradients followed the general performance trend of conventional layered materials; an increase in Ni content improved the capacity, whereas a higher amount of Mn delivered better capacity retention and thermal properties at the expense of capacity. As a result, we determined an optimal level of Mn concentration among the tested FCG cathodes, which maximized the discharge capacity of 188 mAh g^鈥? and had an excellent capacity retention of 96% over 100 cycles operated up to 4.3 V at 25 掳C, with a composition of FCG Li[Ni_0.59Co_0.16Mn_0.25]O₂.