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

• Published in: Journal of the Electrochemical Society 2022-11, Vol.169 (11), p.110527
• Main Authors: Haas, Ronja, Janek, Jürgen
• Format: Article
• Language: English
• Subjects: Li-O2 battery; lithium metal anode; native passivation layer; O2 crossover; solid electrolyte interphase
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1945-7111/ac9d6b

Due to the need for high energy density storage, Li–O 2 batteries and Li metal anodes (LMA) are in the focus of 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 O 2 dissolved in the electrolyte, there are still many unanswered questions, and there are conflicting opinions reported. In this work, plating/stripping experiments are used to show that the Coulomb efficiency is increased by dissolving O 2 in the electrolyte. SEM and XPS analysis of the SEI shows that reaction of the conducting salt with Li metal is the cause of the poor reversibility of the LMA in cells without O 2 . The improved stability in the presence of O 2 can be attributed to a protective Li 2 O and Li 2 CO 3 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 O 2 , which can explain the different results and conclusions in literature.