The formation of solid electrolyte interphase on graphite anodes plays a key role in the efficiency of Li-ion batteries. However, to date, fundamental understanding of the formation of LiF as one of the main solid electrolyte interphase components in hexafluorophosphate-based electrolytes remains elusive. Here, we present experimental and theoretical evidence that LiF formation is an electrocatalytic process that is controlled by the electrochemical transformation of HF impurity to LiF and H₂. Although the kinetics of HF dissociation and the concomitant production of LiF and H₂ is dependent on the structure and nature of surface atoms, the underlying electrochemistry is the same. The morphology, and thus the role, of the LiF formed is strongly dependent on the nature of the substrate and HF inventory, leading to either complete or partial passivation of the interface. Our finding is of general importance and may lead to new opportunities for the improvement of existing, and design of new, Li-ion technologies.

在石墨阳极上形成固态电解质中间相对锂离子电池的效率起着关键作用。然而，迄今为止，对于六氟磷酸酯类电解质中作为主要固体电解质中间相组分之一的LiF形成的基本了解仍然难以捉摸。在这里，我们提供实验和理论证据，表明LiF的形成是一种电催化过程，受HF杂质电化学转化为LiF和H _2的控制。尽管HF分解的动力学以及LiF和H ₂的伴随产生取决于表面原子的结构和性质，其潜在的电化学是相同的。形成的LiF的形态和作用，在很大程度上取决于底物和HF库存的性质，从而导致界面完全或部分钝化。我们的发现具有普遍意义，并可能为改进现有锂离子技术和设计新的锂离子技术带来新的机会。