Origin of voltage decay in high-capacity layered oxide electrodes
Origin of voltage decay in high-capacity layered oxide electrodes
复制标题
DOI：
10.1038/nmat4137
复制
发表时间：
2015-02-01
期刊：
影响因子：
41.2
通讯作者：
Tarascon, J-M.
中科院分区：
文献类型：
--
作者：
Sathiya, M.;Abakumov, A. M.;Tarascon, J-M.
尽管富Li层状氧化物（Li 1 + xNiyCozMn 1-x-y-zO 2> 250 mAhg（-1））是有吸引力的电极材料，其提供的能量密度比当今商业化的Li离子电池高15%以上，但是它们在循环时遭受电压衰减。为了阐明这种现象的起源，我们采用化学取代结构相关的Li 2 RuO 3化合物。富锂层状Li_2Ru_1-yTiyO_3相的容量接近240 mAhg（-1），循环时表现出特征电压衰减。透射电子显微镜和X-射线光电子能谱研究的组合揭示了金属层和Li层之间的阳离子迁移是充放电过程的固有特征，其增加了金属离子在间隙四面体位点中的捕获。通过将研究扩展到Li 2 Ru 1-ySnyO 3和Li 2 RuO 3，建立了这些捕获离子与电压衰减之间的相关性;具有最大离子半径的阳离子衰减最慢。这种效应是强大的，这一发现为开发高容量层状电极提供了新的化学探索，以避免电压衰减。
Although Li-rich layered oxides (Li1+xNiyCozMn1-x-y-zO2 > 250 mAhg(-1)) are attractive electrode materials providing energy densities more than 15% higher than today's commercial Li-ion cells, they suffer from voltage decay on cycling. To elucidate the origin of this phenomenon, we employ chemical substitution in structurally related Li2RuO3 compounds. Li-rich layered Li2Ru1-yTiyO3 phases with capacities of similar to 240mAhg(-1) exhibit the characteristic voltage decay on cycling. A combination of transmission electron microscopy and X-ray photoelectron spectroscopy studies reveals that the migration of cations between metal layers and Li layers is an intrinsic feature of the charge-discharge process that increases the trapping of metal ions in interstitial tetrahedral sites. A correlation between these trapped ions and the voltage decay is established by expanding the study to both Li2Ru1-ySnyO3 and Li2RuO3; the slowest decay occurs for the cations with the largest ionic radii. This effect is robust, and the finding provides insights into new chemistry to be explored for developing high-capacity layered electrodes that evade voltage decay.