Solid electrolyte interphase: Can faster formation at lower potentials yield better performance?
Solid electrolyte interphase: Can faster formation at lower potentials yield better performance?
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DOI：
10.1016/j.electacta.2018.03.007
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发表时间：
2018-04-10
影响因子：
6.6
通讯作者：
Hoster, Harry Ernst
中科院分区：
文献类型：
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作者：
Antonopoulos, Byron Konstantinos;Stock, Christoph;Hoster, Harry Ernst
为了使锂离子电池 (LIB) 在多次循环中可靠地充电，其石墨基负极需要固体电解质中间相 (SEI) 作为保护层。 SEI 是通过制造 LIB 后的第一个充电循环中电解质成分的化学副反应（特别是电化学副反应）形成的。 SEI 理想地有两个目的：(i) 充当可渗透锂离子但不能渗透其他电解质成分的筛子；(ii) 钝化电极以防止电解质进一步分解。传统 SEI 形成的核心要素是漫长的低电流恒电流充电步骤，由于其时间消耗，该步骤极大地增加了电池制造成本。在这里，我们受到最近光滑模型电极实验结果的启发，报告了复合碳电极的一些非常规 SEI 形成方案。认识到 SEI 的形成分为两个主要步骤，分别发生在高电势区域和低电势区域，我们证明在高电势区域花费的时间较少不仅可以使过程更快，甚至可以产生具有优异动力学特性的 SEI。我们通过薄膜生长的基本规则和晶界对离子传输的作用初步解释了这一点。我们还报告了高电位和低电位地层之间应用的多频电位调制的积极影响。鉴于原则上任何新的细胞化学都需要其自己定制的形成过程，未来LIB电池的技术成功将受益于系统化、易于理解的形成方案工具箱。本文只是第一步，强调了潜在的唾手可得的成果，但也标志着对模型系统和商业制造的细胞进行进一步系统研究的需求。 (C) 2018 Elsevier Ltd. 保留所有权利。
To make a Lithium Ion Battery (LIB) reliably rechargeable over many cycles, its graphite-based negative electrode requires the solid electrolyte interphase (SEI) as a protection layer. The SEI is formed through chemical and particularly electrochemical side reactions of electrolyte components in the first charging cycle(s) after manufacturing of a LIB. The SEI ideally serves two purposes: (i) act as a sieve permeable to Li ions but not to other electrolyte components and (ii) passivate the electrode against further electrolyte decomposition. Core element of conventional SEI formation is a lengthy, low-current galvanostatic charging step, which due to its time consumption contributes heavily to cell manufacturing costs. Here, we report on some non-conventional SEI formation protocols for composite carbon electrodes, inspired by recent experimental findings at smooth model electrodes. Acknowledging that the SEI forms in two main steps, taking place in a high-potential and a low-potential region, respectively, we demonstrate that less time spent in the high-potential region not only makes the process faster but even yields SEIs with superior kinetic properties. We tentatively explain this via basic rules of thin film growth and the role of grain boundaries for ion transport. We also report on the positive influence of multi-frequency potential modulations applied between high-potential and low-potential formation. Given that any new cell chemistry in principle requires its own tailor-made formation process, technologic success of future LIB cells will benefit from a systematic, well-understood toolbox of formation protocols. This paper is meant as a first step, highlighting potentially low-hanging fruits, but also flagging the demand for further systematic studies on model systems and on commercially manufactured cells. (C) 2018 Elsevier Ltd. All rights reserved.