Chemical Vapor Treatment to Develop Solid-Electrolyte-Interphase and Remove Residual Lithium Compounds

Abstract

Lithium metal anode (LMA) is considered a promising material for next-generation lithium metal batteries (LMBs). The poor cycling performance of LMBs is due to the presence of residual lithium compounds (RLCs) on the LMA surface, unstable solid-electrolyte interphase (SEI), and lithium dendrite growth. In this study, an atomic layer deposition(ALD)-like process, chemical vapor treatment (CVT) has been utilized to remove RLCs such as LiOH and Li2CO3 from the surface of LMA and develop stable & robust SEI. The XPS investigation shows the conversion of LiOH and Li2CO3 surface contaminants into Li3PO4 via self-limiting surface chemical reactions. Chemical vapor-treated lithium (CVTL) symmetrical cells, and CVTL paired with high capacity/voltage cathodes demonstrated stable cycling, lower voltage hysteresis, and higher-rate capability compared to the bare LMA during electrochemical cycling. The removal of RLCs improves the Li-ion transport and the formation of robust SEI inhibits the continuous side reaction and suppresses the Li dendrite growth. Keywords: chemical vapor treatment, lithium metal anode, solid-electrolyte-interphase, residual lithium compounds, fast charging.