Structure of the Li4Ti5O12 anode during charge-discharge cycling

Abstract

The structural evolution of the zero-strain Li4Ti5O12 anode within a functioning Li-ion battery during charge-discharge cycling was studied using in situ neutron powder-diffraction, allowing correlation of the anode structure to the measured charge-discharge profile. While the overall lattice response controls the zero-strain property, the oxygen atom is the only variable in the atomic structure and responds to the oxidation state of the titanium, resulting in distortion of the TiO6 octahedron and contributing to the anode's stability upon lithiation/delithiation. Interestingly, the trend of the octahedral distortion on charge-discharge does not reflect that of the lattice parameter, with the latter thought to be influenced by the interplay of lithium location and quantity. Here we report the details of the TiO6 octahedral distortion in terms of the O-Ti-O bond angle that ranges from 83.7(3)° to 85.4(5)°.