Li4Ti5O12 as an anode material for Li ion batteries in situ XRD and XPS studies

Abstract: This thesis examines parts of the kinetics and performance in Li-battery cells using lithium titanate anodes and lithium manganese oxide cathodes. Lithium titanate (Li4Ti5O12) is a candidate for battery applications in automotive vehicles due to its long lifetime and its suggested zero-strain ability. The zero-strain ability, meaning no volume changes in the material during cycling, would allow for the high charge/discharge rates required in electric vehicles. Two approaches of analysis have been performed. In situ XRD-analysis was used to verify the zero-strain ability of lithium titanate and XPS studies were used to analyze the surface chemistry of lithium titanate after cycling. It is known that lithium titanate/lithium manganeseoxide battery cells suffer from abnormal gas evolution and power degradation, and it is therefore of interest to find ways to prevent this. To be able to find methods of preventing the performance degradation deeper understanding of the kinetics are needed, since the mechanism behind this is not fully understood. The results in this thesis strengthen the understanding of lithium titanate as a zero-strain material. Furthermore, it is seen that the performance degradation possibly can be avoided or postponed by ALD deposition of aluminium oxide on the surface of the lithium manganese oxide electrode.