High-temperature solid electrolyte interphases (SEI) in graphite electrodes
High-temperature solid electrolyte interphases (SEI) in graphite electrodes
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DOI：
10.1016/j.jpowsour.2018.01.070
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发表时间：
2018-03-31
影响因子：
9.2
通讯作者：
Ajayan, Pulickel M.
中科院分区：
文献类型：
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作者：
Rodrigues, Marco-Tulio F.;Sayed, Farheen N.;Ajayan, Pulickel M.
固体电解质界面（SEI）的热脆性是石墨阳极性能衰减的主要来源，并且克服极端环境给锂离子电池带来的问题的努力取得了有限的成功。在这里，我们证明了SEI可以通过在升高的温度下进行形成周期来广泛增强。在这些条件下，电解质中存在的离子液体的分解有利于形成更厚和更保护的层。其中固体电解质中间相在90 ° C下浇铸的电池在暴露于高温时显著不太容易发生自放电，对形成的SEI没有明显的损害。这种额外的弹性是以牺牲速率能力为代价的，因为电荷转移在这些系统中变得越来越低效。然而，在较慢的速率下，在90 ° C下经历SEI形成的电池表现出上级的性能，这是由于改善了Li+通过SEI的传输，以及电解质对石墨的最佳润湿。这项工作分析了不同的石墨基质和离子液体，表明这种效应比预期的更普遍，并提供了独特的视角，即对于某些系统，温度实际上可以成为钝化的一种资产。
Thermal fragility of the solid electrolyte interphase (SEI) is a major source of performance decay in graphite anodes, and efforts to overcome the issues offered by extreme environments to Li-ion batteries have had limited success. Here, we demonstrate that the SEI can be extensively reinforced by carrying the formation cycles at elevated temperatures. Under these conditions, decomposition of the ionic liquid present in the electrolyte favored the formation of a thicker and more protective layer. Cells in which the solid electrolyte interphase was cast at 90 degrees C were significantly less prone to self-discharge when exposed to high temperature, with no obvious damages to the formed SEI. This additional resilience was accomplished at the expense of rate capability, as charge transfer became growingly inefficient in these systems. At slower rates, however, cells that underwent SEI formation at 90 degrees C presented superior performances, as a result of improved Li+ transport through the SEI, and optimal wetting of graphite by the electrolyte. This work analyzes different graphite hosts and ionic liquids, showing that this effect is more pervasive than anticipated, and offering the unique perspective that, for certain systems, temperature can actually be an asset for passivation.