Synthesis and electrochemical properties of Li-excess Li_1+x[Ni_0.5Co_0.2Mn_0.3]O₂ cathode materials using ammonia-free chelating agent

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• 作者：Ji-Zhou Kong ; Xiao-Yan Yang ; Hai-Fa Zhai ; Chong Ren ; Hui Li ; Jun-Xiu Li ; Zhou Tang ; Fei Zhou
• 关键词：Li-ion battery ; Cathode material ; Li-excess Li1+x(Ni0.5Co0.2Mn0.3)O2 ; Cation mixing ; Electrochemical property
• 刊名：Journal of Alloys and Compounds
• 出版年：2013
• 出版时间：15 December, 2013
• 年：2013
• 卷：580
• 期：Complete
• 页码：491-496
• 全文大小：1266 K

文摘

Hydroxide precursor Ni_0.5Co_0.2Mn_0.3(OH)₂ with average particle size of about 9.88 ¦Ìm was prepared via co-precipitation method using oxalic acid as an ammonia-free chelating agent. Well-ordered layer-structured LiNi_0.5Co_0.2Mn_0.3O₂ was synthesized with controlling the Li/(Ni + Co + Mn) molar ratio by calcining the uniform metal hydroxide with Li₂CO₃ at 850 ¡ãC. The effect of excessive Li on the structural and electrochemical properties of the final compounds Li_1+x(Ni_0.5Co_0.2Mn_0.3)O₂ (0 ? x ? 0.2) was deeply investigated. Excessive Li is favorable to suppress the degree of cation mixing and improve the hexagonal ordering, indicated by the improved value of I_(1 0 3)/I_(1 0 4) and the decreased value of (I_(0 0 6) + I_(1 0 2))/I_(1 0 1). Higher discharge capacity, as well as better cyclability and rate capability, was achieved for the Li-excess Li_1+x(Ni_0.5Co_0.2Mn_0.3)O₂ compounds, especially the sample of Li_1.1(Ni_0.5Co_0.2Mn_0.3)O₂, compared with that of Li(Ni_0.5Co_0.2Mn_0.3)O₂. It is believed that such enhanced electrochemical performances are related to the improved physical and structural properties of the Li-excess samples.