Effect of Electrolyte Additives on Li 4 Ti 5 O 12 Cycling Performance and Gas Evolution

Abstract

Batteries consisting of Li4Ti5O12 (LTO) anodes do not require the formation of a solid electrolyte interface to deliver robust high-rate performance at room temperature, however performance suffers at elevated temperatures due to gas evolution. Research has linked gas evolution to the instability of the electrolyte on the surface of charged LTO at elevated temperatures. If this is the case, a passivation layer, which prevents the electrolyte from coming into contact with the charged surface of LTO, should inhibit gas evolution. Several classes of electrolyte additives have been investigated in Li4Ti5O12/LiMn2O4 coin cells and pouch cells. ATR-IR and X-ray photoelectron spectroscopy has been used to gain an understanding of the surface films formed with different additives while in-situ gas measurements based on Archimedes’ principle and gas chromatography have given insight into how the implementation of these additives affects gassing. The results from this study enable the selective design of surface films for LTO anodes, which reduces gassing at elevated temperatures without sacrificing performance.