Preparation of a spinel Li4Ti5O12 (111) surface from a rutile TiO2 single crystal

Abstract Spinel Li 4 Ti 5 O 12 is a very promising material for electrodes in a wide range of Li-ion battery applications because of its unique Li-insertion/extraction properties. Although the bulk properties of Li 4 Ti 5 O 12 have been studied intensively, there have been few reports about the structure and properties of Li 4 Ti 5 O 12 surfaces in spite of the importance of solid/electrolyte interfaces. This is because of the difficulty in preparing Li 4 Ti 5 O 12 samples with accessible flat surfaces suitable for scanning probe microscopy study. To address this, we have successfully prepared a flat Li 4 Ti 5 O 12 crystal surface by solid state reaction from a rutile TiO 2 (1 1 1) wafer with LiOH·H 2 O powder. Out-of-plane X-ray diffraction (XRD) and transmission electron microscopy revealed that a highly oriented and crystallized Li 4 Ti 5 O 12 (1 1 1) film was formed on the TiO 2 (1 1 1) wafer. Atomic force microscopy observations revealed that an atomically flat Li 4 Ti 5 O 12 (1 1 1) surface was formed on the film with terraces of 200–300 nm width and steps of a {1 1 1} interplanar height. The formed thin films were also investigated by cyclic voltammetry and galvanostatic experiments, revealing that the films have electrochemical activity as battery electrodes.