The Influence of Oxygen Dissolved in the Liquid Electrolyte on Lithium Metal Anodes

Abstract

Due to the need for high-energy-density storage, Li-O2 batteries and Li metal anodes (LMA) are a focus of extensive research. As safe operation of the LMA is yet not possible, more knowledge about factors influencing the stability of the solid electrolyte interphase (SEI) is necessary to utilize the LMA. Especially concerning the influence of O2 dissolved in the electrolyte, there are still many unanswered questions, and there are conflicting opinions reported. Here, plating/stripping experiments were used to show that the Coulomb efficiency is increased by dissolving O2 in the electrolyte. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis of the SEI shows that reaction of the conducting salt with Li metal is the cause of poor reversibility of the LMA in cells without O2. The improved stability in the presence of O2 can be attributed to a protective Li2O and Li2CO3 rich SEI that prevents degradation. In addition, the SEI on freshly deposited Li is compared to that on a commercial Li foil. The reactivity of the native passivation layer formed on the Li foil during storage differs significantly from that of plated Li regarding the influence of O2, which can explain the different results and conclusions in literature.

Insights into the LiI Redox Mediation in Aprotic Li–O2 Batteries: Solvation Effects and Singlet Oxygen Evolution

“…It is likely that also a contribution from Li 2 SO 3 is present, as a result of LiTFSI degradation, in agreement with previous findings. 43 The EDX elemental analysis reported in Table 2 indicates high quantities of sulfur and fluorine, confirming the predominance of LiTFSI fragments in SEI composition. Overall, the effect of DMSO solvation on LiI redox mediation has a detrimental impact on the stability of cell changes occur in the G4 solution.…”

In Situ Spectroscopic Probing of Oxygen Crossover Effects on Solid Electrolyte Interphase in Aprotic Lithium‐Oxygen Batteries

“…Conversely, some other works reported that the SEI layer is more stable in the oxygenated electrolyte than the pristine electrolyte. [ 20–23 ] For instance, Zhou et al. [ 23 ] and Haas et al.…”

“…[ 23 ] and Haas et al. [ 20 ] reported that the oxygen can preferentially react with LMA to form an inorganic‐rich SEI layer (e.g., Li 2 O, Li 2 O 2 , and Li 2 CO 3 ), to prevent the further degradation of LMA. Grey et al.…”

“…Conversely, some other works reported that the SEI layer is more stable in the oxygenated electrolyte than the pristine electrolyte. [20][21][22][23] For instance, Zhou et al [23] and Haas et al [20] reported that the oxygen can preferentially react with LMA to form an inorganic-rich SEI layer (e.g., Li 2 O, Li 2 O 2 , and Li 2 CO 3 ), to prevent the further degradation of LMA. Grey et al [22] found that oxygen could participate in electrolyte reduction to form a homogeneous SEI in TEGDME-based electrolytes.…”

Lithium magnesium alloys: a framework for investigating lithium alloy anodes for solid state batteries

“…Fig. 3D-F [39,40], oxide, hydroxide and others. All 338 three alloy passivation layers consist of a combination 339 of magnesium oxide and lithium compounds, but the 340 relative fractions vary.…”