Effects of soluble products decomposed from chelato-borate additives on formation of solid electrolyte interface layers.

The prevailing account attributes the positive effects of boron-based additives on solid electrolyte interface (SEI) layers to its solid products by prior decomposition. However, this study proves the BOF2− anion, a soluble product of film formation additive of lithium difluoro(oxalato)borate, plays a crucial role in improving the SEI layer. Specifically, BOF2− suppresses the excessive decomposition of salt anions by aggregating on the electrode surface. Meanwhile, it catalyzes the reduction of ethylene carbonate, leading to improving the stability of the interface. In the end, ultrasound shaking is used to generate more BOF2− anion and increase the cycle performance of cells at a high rate as excepted. This work helps to understand the effects of soluble products on the SEI forming process and provides new insights for improving the stability of electrode electrolyte interfaces. [Display omitted] • An effect mechanism of SEI formation is proved from the view of soluble product. • The soluble product of LiDFOB prevents its excessive decomposition. • The soluble product catalyzes the reduction of EC. [ABSTRACT FROM AUTHOR]