npj：锂离子电池（LIB）阳极固体电解质界面——想要模拟？
海归学者发起的公益学术平台
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交流学术，偶尔风月
可再充式锂离子电池（LIB）给我们的工作和生活掀起了巨大的波澜，推动了小型电子产品、航空领域电器的变革：因其更高的能量密度而逐渐取代了传统的碱性电池、镍镉电池和铅酸电池等。自1991年索尼公司首次将LIB商业化以来，仅二十多年的时间，锂离子电池的能量密度逐年增加（~5 Wh/kg /Year），现在已达160 Wh/kg，但仍不能满足汽车电气化的要求（500 - 700 Wh/kg）。固体电解质界面（SEI）是由电解质的分解产物在电极表面上形成的钝化层，允许Li +传输但阻挡电子通过，可防止电解质进一步分解，确保电化学反应能够持续。该领域有可能成为LIB的下一个技术突破点。由于SEI纳米膜结构复杂，加之可靠的原位实验技术缺乏，其形成和生长机理均未完全明了。计算方法方面的重大进展使SEI形成机制的预测性模拟成为可能。来自上海大学的施思齐教授和美国密西根州立大学的齐月教授，综述了SEI计算模拟领域的最新研究进展，涉及电子结构计算到介观尺度模型，涵盖电解质还原反应的热力学和动力学、SEI形成、通过电解质设计来改性、SEI特性与电池性能间的关联，以及人工SEI的设计；总结了多尺度模拟，比较了模拟结果与实验结果；讨论了SEI基本性质的计算细节，如：电子隧道效应、锂离子传输、块体SEI和电极/(SEI/)电解质界面的化学/机械稳定性等。综述最后展望了计算方法在SEI性质解析和人工SEI设计中的应用前景，并相信计算模拟与实验相结合可以相互补充，从而更好地了解SEI的复杂特性，以利将来开发出更高效的电池。
Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries
Aiping Wang, Sanket Kadam, Hong Li,
Siqi Shi & Yue Qi
A passivation layer called the solid electrolyte interphase (SEI) is formed on electrode surfaces from decomposition products of electrolytes. The SEI allows Li+ transport and blocks electrons in order to prevent further electrolyte decomposition and ensure continued electrochemical reactions. The formation and growth mechanism of the nanometer thick SEI films are yet to be completely understood owing to their complex structure and lack of reliable in situ experimental techniques. Significant advances in computational methods have made it possible to predictively model the fundamentals of SEI. This review aims to give an overview of state-of-the-art modeling progress in the investigation of SEI films on the anodes, ranging from electronic structure calculations to mesoscale modeling, covering the thermodynamics and kinetics of electrolyte reduction reactions, SEI formation, modification through electrolyte design, correlation of SEI properties with battery performance, and the artificial SEI design. Multi-scale simulations have been summarized and compared with each other as well as with experiments. Computational details of the fundamental properties of SEI, such as electron tunneling, Li-ion transport, chemical /mechanical stability of the bulk SEI and electrode/(SEI/) electrolyte interfaces have been discussed. This review shows the potential of computational approaches in the deconvolution of SEI properties and design of artificial SEI. We believe that computational modeling can be integrated with experiments to complement each other and lead to a better understanding of the complex SEI for the development of a highly efficient battery in the future.
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