Direct In situ Observation of Li2O Evolution on Li-Rich High-Capacity Cathode Material, Li[NixLi(1–2x)/3Mn(2–x)/3]O2

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• 作者：Sunny Hy ; Felix Felix ; John Rick ; Wei-Nien Su ; Bing Joe Hwang
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：January 22, 2014
• 年：2014
• 卷：136
• 期：3
• 页码：999-1007
• 全文大小：783K
• ISSN：1520-5126

文摘

High-capacity layered, lithium-rich oxide cathodes show great promise for use as positive electrode materials for rechargeable lithium ion batteries. Understanding the effects of oxygen activating reactions on the cathode鈥檚 surface during electrochemical cycling can lead to improvements in stability and performance. We used in situ surfaced-enhanced Raman spectroscopy (SERS) to observe the oxygen-related surface reactions that occur during electrochemical cycling on lithium-rich cathodes. Here, we demonstrate the direct observation of Li<sub>2sub>O formation during the extended plateau and discuss the consequences of its formation on the cathode and anode. The formation of Li<sub>2sub>O on the cathode leads to the formation of species related to the generation of H<sub>2sub>O together with LiOH and to changes within the electrolyte, which eventually result in diminished performance. Protection from, or mitigation of, such devastating surface reactions on both electrodes will be necessary to help realize the potential of high-capacity cathode materials (270 mAhg<sup>鈥?sup> versus 140 mAhg<sup>鈥?sup> for LiCoO<sub>2sub>) for practical applications.