Effects of Solid Electrolyte Interphase Components on the Reduction of LiFSI over Lithium Metal

The use of a lithium metal anode still presents a challenging chemistry and engineering problem that holds back next generation lithium battery technology. One of the issues facing lithium metal is the presence of the solid electrolyte interphase (SEI) layer that forms on the electrode creating a variety of chemical species that change the properties of the electrode and is closely related to the formation and growth of lithium dendrites. In order to advance the scientific progress of lithium metal more must be understood about the fundamentals of the SEI. One property of the SEI that is particularly critical is the passivating behavior of the different SEI components. This property is critical to the continued formation of SEI and stability of the electrolyte and electrode. Here we report the investigation of the passivation behavior of Li2O, Li2CO3, LiF and LiOH with the lithium salt LiFSI. We used large computational chemistry models that are able to capture the lithium/SEI interface as well as the SEI/electrolyte interface. We determined that LiF and Li2CO3 are the most passivating of the SEI layers, followed by LiOH and Li2O. These results match previous studies of other Li salts and provide further examination of LiFSI reduction. A solid electrolyte interphase forms by electron transfer from the Li metal anode to the electrolyte. The physical and chemical properties of the components (LiF, LiOH, Li2O, Li2CO3) induce different passivity behaviors for the decomposition of the salt anion (LiFSI).