Effect of the Electrolyte Composition on SEI Reactions at Si Anodes of Li-Ion Batteries
Effect of the Electrolyte Composition on SEI Reactions at Si Anodes of Li-Ion Batteries
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DOI：
10.1021/acs.jpcc.5b01228
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发表时间：
2015-04-02
影响因子：
3.7
通讯作者：
Balbuena, Perla B.
中科院分区：
文献类型：
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作者：
de la Hoz, Julibeth M. Martinez;Soto, Fernando A.;Balbuena, Perla B.
由于电解质组分的还原分解而在硅阳极表面形成的固体电解质界面（SEI）层是对电池性能产生负面影响的不可逆容量损失的部分原因。我们使用从头算分子动力学模拟研究如何电解质组合物，包括有机碳酸酯和LiPF 6影响这样的反应。溶剂极性定义了盐的解离，并且在盐和溶剂/添加剂解离之间存在竞争。盐阴离子分解，产生一个PF 3基团和三个F阴离子。PF 3基团相对稳定，但在一段时间后，它分解成LiF在阳极表面上成核。在阴离子分解过程中，P原子逐渐减少，最终与表面原子或溶剂/添加剂分解的片段偶联，所述溶剂/添加剂分解在盐分解之前或与盐分解同时发生。发现了碳酸亚乙烯酯与表面反应生成CO2和锂氧化物前体成核的新途径。
Solid-electrolyte interphase (SEI) layers formed at the surface of silicon anodes due to reductive decomposition of the electrolyte components are partially responsible of the irreversible capacity loss that negatively affects battery performance. We use ab initio molecular dynamics simulations to investigate how the electrolyte composition including organic carbonates and LiPF6 affects such reactions. Solvent polarity defines salt dissociation, and there is a competition between salt and solvent/additive dissociation. The salt anion decomposes, yielding a PF3 group and three F anions. The PF3 group is relatively stable, but after some time, it decomposes nucleating on the anode surface as LiF. During anion decomposition the P atom progressively reduces finally becoming coupled to a surface atom or to fragments of the solvent/additive decomposition that takes place prior or simultaneously with the salt decomposition. New pathways are found for formation of CO2 from vinylene carbonate reaction with the surface and for nucleation of Li oxide precursors.