Spinel lithium titanium oxide Li4Ti5O12 (LTO), is an intriguing anode material due to its high cycling stability resulting in a long life time for batteries. However, its use is still limited due to its low intrinsic electronic conductivity. One way to overcome this drawback, is to introduce defects during sintering in a reductive atmosphere. Up to now, only little is known about the real nature of those defects and their exact influence on material properties. We performed positron annihilation spectroscopy (PAS) and coincident Doppler broadening spectroscopy (CDBS) measurements combined with rst-principles calculations within the framework of two-component density functional theory (TCDFT) to reveal the nature of these defects and their distribution. The measurements exhibit a pronounced influence of the annealing time on the measured oxygen defect concentration. In particular, the recorded depth pro le shows a gradient of defects, decreasing from the surface to the bulk. This can be used to tailor the optimum surface to bulk to defect to optimize the conductivity for the LTO used as an anode material. Overall, we present a tight combination of theory and experiments that is strictly required for a successful interpretation of positron measurements of complex disordered materials such as LTO.

Li4Ti5O12 (LTO) antimatter meets defects: Combined theoretical and experimental approach

2019 Fall National Meeting

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