Effects of Atmospheric Gases on Li Metal Cyclability and Solid-Electrolyte Interphase Formation

High Resolution Image Download MS PowerPoint Slide For Li–air batteries, dissolved gas can cross over from the air electrode to the Li metal anode and affect the solid-electrolyte interphase (SEI) formation, a phenomenon that has not been fully characterized. In this work, the impact of atmospheric gases on the SEI properties is studied using electrochemical methods and ex situ characterization techniques, including X-ray photoelectron spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The presence of O 2 significantly improved the lithium cyclability; less lithium is consumed to form the SEI or is lost because of electrical disconnects. However, the SEI resistivity and plating overpotentials increased. Lithium cycled in an “air-like” mixed O 2 /N 2 environment also demonstrated improved cycling efficiency, suggesting that dissolved O 2 participates in electrolyte reduction, forming a homogeneous SEI, even at low concentrations. The impact of gas environments on Li metal plating and SEI formation represents an additional parameter in designing future Li-metal batteries.