Role of AlF3 Coating on LiCoO2 Particles during Cycling to Cutoff Voltage above 4.5 V
Role of AlF3 Coating on LiCoO2 Particles during Cycling to Cutoff Voltage above 4.5 V
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DOI：
10.1149/1.3236501
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发表时间：
2009-01-01
影响因子：
3.9
通讯作者：
Amine, Khalil
中科院分区：
文献类型：
--
作者：
Sun, Yang-Kook;Yoon, Chong Seung;Amine, Khalil
电池测试表明，使用AlF3涂层可以使LiCoO2电极在4.54 V的最高截止电压下提供更高的放电容量（208 mAh g(-1)）。循环50次后，其容量保留率约为94%，而在4.5 V电压下，原始LiCoO2的容量保留率仅为60%。AlF3涂层改善了电化学性能，这是由于循环过程中LiCoO2结构降解的延迟。对循环LiCoO2电极的结构分析表明，在循环过程中，原始LiCoO2通过Co的逐步化学浸出引发的中间相转变为立方尖晶石相。AlF3涂层保护LiCoO2不受HF的化学侵蚀，从而有助于延缓最终的尖晶石相转变。通过延缓这一转变，AlF3涂层在4.5 V以上循环时能够降低电荷转移电阻并保持结构稳定性。(C) 2009电化学学会。[DOI: 10.1149/1.3236501]版权所有。
Cell tests demonstrated that the use of an AlF3 coating enabled a LiCoO2 electrode to deliver a higher discharge capacity (208 mAh g(-1)) at an upper cutoff voltage of 4.54 V. About 94% of the initial capacity was retained after 50 cycles, while the capacity retention of pristine LiCoO2 was only 60% at 4.5 V. The improved electrochemical performance with the AlF3 coating was attributed to the delay of structural degradation of LiCoO2 during cycling. A structural analysis of the cycled LiCoO2 electrode revealed that the pristine LiCoO2 transforms to a cubic spinel phase via an intermediate phase triggered by progressive chemical leaching of Co during cycling. The AlF3 coating protected LiCoO2 from the chemical attack by HF and thus helped to delay the eventual phase transformation to a spinel phase. By delaying this transformation, the AlF3 coating was able to reduce the charge-transfer resistance and maintain the structural stability when cycled above 4.5 V. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3236501] All rights reserved.