Understanding the effect of Co3+substitution on the electrochemical properties of lithium-rich layered oxide cathodes for lithium-ion batteries
Understanding the effect of Co3+substitution on the electrochemical properties of lithium-rich layered oxide cathodes for lithium-ion batteries
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DOI：
10.1021/jp506731v
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发表时间：
2014-09
影响因子：
3.7
通讯作者：
X. Xiang;James C. Knight;Weishan Li;A. Manthiram
中科院分区：
文献类型：
--
作者：
X. Xiang;James C. Knight;Weishan Li;A. Manthiram
本文系统地研究了Co ~（3+）等量替代富锂层状氧化物正极材料Li[Li_（0.2）Ni_（0.2-x）/2 Mn_（0.6-x）/2Cox] O_2（0 ≤ x ≤ 0.24）中Mn ~（4+）和Ni ~（2+）的效果。在锂离子电池中的电化学充电/放电测量表明，在第一次充电期间从晶格中的氧损失是动力学缓慢的过程，但是由于Co 3 +/4+：t2 g带与O2-：2 p带的顶部的重叠以及金属-氧共价的增加，可以通过Co 3+的取代来改善氧损失。虽然随着Co 3+取代的增加而增加的氧损失导致更高的可逆容量，但是由于在第一次放电期间产生的较高浓度的Mn 3+离子，第一次循环放电电压略微降低。然而，容量衰减和电压衰减增加，在延长的循环过程中，由于增加过渡金属离子的迁移到锂层，这是由更高的数目促进的Co 3+取代增加。
The effect of the substitution of Co3+ for equal amounts of Mn4+ and Ni2+ in the lithium-rich layered oxide cathode Li[Li0.2Ni0.2–x/2Mn0.6–x/2Cox]O2 (0 ≤ x ≤ 0.24) has been investigated systematically. Electrochemical charge/discharge measurements in lithium-ion cells indicate that the oxygen loss from the lattice during the first charge is a kinetically slow process, but it can be improved by the substitution of Co3+ due to an overlap of the Co3+/4+:t2g band with the top of the O2–:2p band and an increase in metal–oxygen covalence. Although the increased oxygen loss with increasing Co3+ substitution leads to a higher reversible capacity, the first cycle discharge voltage decreases slightly due to the higher concentration of Mn3+ ions created during the first discharge. However, both the capacity fade and the voltage decay increase during extended cycling with increasing Co3+ substitution due to an increasing migration of the transition-metal ions to the lithium layer, which is promoted by the higher numb...