ALD Protection of Li-Metal Anode Surfaces – Quantifying and Preventing Chemical and Electrochemical Corrosion in Organic Solvent

Chemical and electrochemical instability of the Li metal interface with organic solvent has been a major impediment to use of Li-metal anodes for next-generation batteries. Here the character of Li surface degradation and the application of atomic layer deposition (ALD) as a protection layer to suppress the degradation are addressed. Using standard Li foil samples in organic solvent with and without in situ deposited ALD Al₂O₃ protective layers, results from in situ atomic force microscopy, mass spectrometry (including differential electrochemical mass spectrometry), X-ray Photoelectron Spectroscopy (XPS), and ex situ scanning electron microscopy/energy dispersive X-ray spectroscopy are reported. Despite the presence of a thin oxide/hydroxide/carbonate layer on the Li foil surface, degradation readily occurs in organic solvent, particularly at surface features such as ridges. Introduction of the ALD protective layer – deposited directly on this Li foil surface – dramatically suppresses the degradation.