Direct In situ Observation of Li2O Evolution on Li-Rich High-Capacity Cathode Material, Li[NixLi(1-2x)/3Mn(2-x)/3]O2 (0 ≤ x ≤ 0.5)
Direct In situ Observation of Li2O Evolution on Li-Rich High-Capacity Cathode Material, Li[NixLi(1-2x)/3Mn(2-x)/3]O2 (0 ≤ x ≤ 0.5)
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DOI：
10.1021/ja410137s
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发表时间：
2014-01-22
影响因子：
15
通讯作者：
Hwang, Bing Joe
中科院分区：
文献类型：
--
作者：
Hy, Sunny;Felix, Felix;Hwang, Bing Joe
高容量层状富锂氧化物正极显示出用作可充电锂离子电池正极材料的巨大前景。了解电化学循环过程中氧活化反应对阴极表面的影响可以提高稳定性和性能。我们使用原位表面增强拉曼光谱（SERS）来观察富锂正极电化学循环过程中发生的与氧相关的表面反应。在这里，我们展示了在延长平台期间直接观察 Li2O 形成的情况，并讨论了其形成对阴极和阳极的影响。阴极上形成的 Li2O 会导致与 H2O 和 LiOH 一起生成相关的物质的形成，以及电解质内的变化，最终导致性能下降。为了帮助实现高容量正极材料（LiCoO2 为 270 mAhg(-1) 与 140 mAhg(-1)）在实际应用中的潜力，必须防止或减轻两个电极上这种破坏性的表面反应。
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's 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 Li2O formation during the extended plateau and discuss the consequences of its formation on the cathode and anode. The formation of Li2O on the cathode leads to the formation of species related to the generation of H2O 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(-1) versus 140 mAhg(-1) for LiCoO2) for practical applications.