In Situ Detection of Lithium Plating on Graphite Electrodes by Electrochemical Calorimetry
In Situ Detection of Lithium Plating on Graphite Electrodes by Electrochemical Calorimetry
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DOI：
10.1149/2.049304jes
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发表时间：
2013-01-01
影响因子：
3.9
通讯作者：
Dahn, J. R.
中科院分区：
文献类型：
--
作者：
Downie, L. E.;Krause, L. J.;Dahn, J. R.
在充电条件下测量的石墨/NMC锂离子电池的热流显示出一个在石墨电极上镀锂开始时的特征和容易识别的信号：热流的显著下降标志着石墨主体的完全锂化。这个信号的起源被证明是由熵和细胞过电势的综合效应引起的。这一信号允许准确测量主体中可能的最大锂嵌入量。在热流开始下降后，金属锂沉积开始在5-7mAh/g范围内。检测了两种不同类型的石墨：G25和MCMB。测得G25石墨和MCMB石墨的初始镀锂时间分别为336mAhg和297mAhg，分别得到Li0.888C6和Li0.804C6的经验公式。通过库仑效率、寄生热能和电池容量衰减的精确测量，考察了镀锂对电极/电解液反应性的影响。通过这些测量，可以计算出在石墨表面镀锂的效率：025和MCMB石墨的电镀效率分别为0.98和0.97。(C)2013年电化学会。[DOI：10.1149/2.049304jes]版权所有。
The measured heat flow of graphite/NMC lithium ion cells under charging conditions show a characteristic and easily identifiable signal at the onset of lithium plating on the graphite electrode: A marked decrease in heat flow signals the full lithiation of the graphite host. The origin of this signal is shown to arise from the combined effects of entropy and cell over potentials. This signal allows for an accurate measure Of the maximum amount of lithium intercalation possible in the host. Metallic lithium deposition begins within 5-7 mAh/g after the heat flow begins to decrease. Two different types of graphite were examined; G25 and MCMB. The onset of lithium plating was detected at 336 mAh/g for the G25 graphite and 297 mAh/g for the MCMB graphite, yielding empirical formulas of Li0.888C6 and Li0.804C6, respectively. The effect of plated lithium on the electrode/electrolyte reactivity was also examined by precise measurement of the coulombic efficiency, parasitic thermal energy and cell capacity fade. These measurements then allowed for the calculation of the efficiency of lithium plating on the graphite surface: 0.98 and 0.97 for 025 and MCMB graphites, respectively. (C) 2013 The Electrochemical Society. [DOI: 10.1149/2.049304jes] All rights reserved.