Kuai Dacheng, Balbuena Perla B
Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, United States.
Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States.
J Phys Chem C Nanomater Interfaces. 2023 Jan 23;127(4):1744-1751. doi: 10.1021/acs.jpcc.2c07838. eCollection 2023 Feb 2.
Solid electrolyte interphase (SEI) engineering is an efficient approach to enhancing the cycling performance of lithium metal batteries. Lithium hexafluorophosphate (LiPF) is a popular electrolyte salt. Mechanistic insights into its degradation pathways near the lithium metal anode are critical in modifying the battery electrolyte and SEI. In this work, we elucidate plausible reaction pathways in multiple representative electrolyte systems. Through ab initio molecular dynamics simulations, lithiation and electron transfer are identified as the triggering factors for LiPF degradation. Meanwhile, we find that lithium morphology and charge distribution substantially impact the interfacial dissociation pathways. Thermodynamic evaluation of the solvation effects shows that higher electrolyte dielectric constant and lithiation extent profoundly assist the LiPF decomposition. These findings offer quantitative thermodynamic and electronic structure information, which promotes rational SEI engineering and electrolyte tuning for lithium metal anode performance enhancement.
固态电解质界面（SEI）工程是提高锂金属电池循环性能的有效方法。六氟磷酸锂（LiPF）是一种常用的电解质盐。深入了解其在锂金属阳极附近的降解途径对于改进电池电解质和SEI至关重要。在这项工作中，我们阐明了多种代表性电解质体系中可能的反应途径。通过从头算分子动力学模拟，锂化和电子转移被确定为LiPF降解的触发因素。同时，我们发现锂的形态和电荷分布对界面解离途径有显著影响。溶剂化效应的热力学评估表明，较高的电解质介电常数和锂化程度极大地促进了LiPF的分解。这些发现提供了定量的热力学和电子结构信息，有助于合理设计SEI和调整电解质，以提高锂金属阳极的性能。
