The effect of electrolyte temperature on the passivity of solid electrolyte interphase formed on a graphite electrode
The effect of electrolyte temperature on the passivity of solid electrolyte interphase formed on a graphite electrode
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DOI：
10.1016/s0008-6223(02)00144-6
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发表时间：
2002
期刊：
影响因子：
10.9
通讯作者：
Seung-Bok Lee;S. Pyun
中科院分区：
文献类型：
--
作者：
Seung-Bok Lee;S. Pyun
在1 M LiPF 6-碳酸亚乙酯/碳酸二乙酯（50：50 vol. %）中研究了电解质温度对固体电解质界面（SEI）钝化性的影响。电解质，采用恒电流充放电实验，交流阻抗谱结合傅里叶变换红外光谱，和高分辨率透射电子显微镜（HRTEM）。在20°C下的恒电流充放电曲线证明，电化学循环期间的不可逆容量损失随着SEI形成温度从0 ° C升高到40°C而显著增加。这意味着SEI形成温度越高，石墨电极暴露于结构损伤的越多。根据随着SEI形成温度的升高，Li 2CO 3相对于ROCO 2Li的相对量增加，以及通过SEI层的锂传输的阻力降低，可以合理地认为，由于在ROCO 2Li向Li 2CO 3的转化过程中增强的气体析出反应，升高的SEI形成温度增加了SEI层中缺陷位点的数量。从HRTEM图像的分析，在充电-放电循环后，未观察到块状石墨层中的显著结构破坏。这意味着溶剂化的锂离子通过SEI中的缺陷位点最多嵌入到石墨层的表面区域中。
The effect of electrolyte temperature on the passivity of solid electrolyte interphase (SEI) was investigated in 1 M LiPF6-ethylene carbonate/diethyl carbonate (50:50 vol.%) electrolyte, using galvanostatic charge–discharge experiment, and ac-impedance spectroscopy combined with Fourier transform infra-red spectroscopy, and high resolution transmission electron microscopy (HRTEM). The galvanostatic charge–discharge curves at 20°C evidenced that the irreversible capacity loss during electrochemical cycling was markedly increased with rising SEI formation temperature from 0 to 40°C. This implies that the higher the SEI formation temperature, the more were the graphite electrodes exposed to structural damages. From both increase of the relative amount of Li2CO3to ROCO2Li and decrease of resistance to the lithium transport through the SEI layer with increasing SEI formation temperature, it is reasonable to claim that, due to the enhanced gas evolution reactions during transformation of ROCO2Li to Li2CO3, the rising SEI formation temperature increased the number of defect sites in the SEI layer. From the analysis of HRTEM images, no significant structural destruction in bulk graphite layer was observed after charge–discharge cycles. This means that solvated lithium ions were intercalated through the defect sites in the SEI, at most, into the surface region of the graphite layer.