Preparation of spherical hierarchical LiNi0.5Mn1.5O4 with high electrochemical performances by a novel composite co-precipitation method for 5 V lithium ion secondary batteries
Preparation of spherical hierarchical LiNi0.5Mn1.5O4 with high electrochemical performances by a novel composite co-precipitation method for 5 V lithium ion secondary batteries
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DOI：
10.1016/j.electacta.2013.10.167
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发表时间：
2014-04
影响因子：
6.6
通讯作者：
Zhi Zhu;Qilu;Ding Zhang;Haiying Yu
中科院分区：
文献类型：
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作者：
Zhi Zhu;Qilu;Ding Zhang;Haiying Yu
提出了一种新型的复合共沉淀法制备高性能LiNi0.5Mn1.5O4。结合水热处理，得到了精确化学计量比的LiNi0.5Mn1.5O4。产品具有典型的Fd3m结构，同时对Mn 3+的含量有严格限制。此外，所制备的LiNi0.5Mn1.5O4具有由纳米或亚微米级初级颗粒组成的球形分级形貌。与传统方法相比，所制备的LiNi0.5Mn1.5O4具有优异的电化学性能。它提供了144.9 mAh g− 1的高容量和98.1%的高初始库仑效率，重要的是在4.7 V平台下98.2%的容量放电。在0.3C、1C和3C下循环200次后，材料的容量分别保持96.3%、94.4%和91.1%。化学和电化学测试表明，尖晶石中Mn 3+的消除是LiNi 0.5Mn 1.5O4在4.7V高压下放电容量高的原因。球形分级形态以及保留的Fd3m结构有效地有利于速率性能。此外，这种分级形态在提高阴极材料的振实密度方面也起着重要作用。
A novel composite co-precipitation method is developed to prepare high performance LiNi0.5Mn1.5O4. Combined with a facile hydrothermal treatment, a precise stoichiometric LiNi0.5Mn1.5O4is obtained. The product has classic Fd3m structure, and meanwhile the content of Mn3+is strictly limited. Additionally, the as-prepared LiNi0.5Mn1.5O4has a spherical hierarchical morphology, composed of nano or submicron primary particles. Compared to traditional methods, the obtained LiNi0.5Mn1.5O4shows superlative electrochemical performances. It delivers a high capacity of 144.9 mAh g−1and a high initial columbic efficiency of 98.1%, importantly 98.2% of the capacity discharges at 4.7 V plateau. After 200 cycles under 0.3 C, 1 C and 3 C, the material retains 96.3%, 94.4% and 91.1% of the original capacities, respectively. Chemical and electrochemical measurements indicate that it is the elimination of Mn3+in the spinel that leads to the high capacity of LiNi0.5Mn1.5O4discharging at 4.7 V high voltage. The spherical hierarchical morphology as well as the retained Fd3m structure effectively favors the rates performance. In addition, this hierarchical morphology also plays a significant role in improving the tap density of the cathode material.