A surface-supporting method for an anode material of Li4Ti5O12 via an epitaxial thin film approach

High-speed rechargeability is essential for next-generation secondary batteries. We previously reported that a surface-supporting material deposited on a cathode material accelerates Li-ion motions between an electrode−electrolyte interface by an electric field concentration at a supporting material–cathode–electrolyte (triple-phase) interface (TPI). In addition, a high relative permittivity material was found to be a promising supporting material with which to reinforce the electric field concentration at TPIs. However, the TPI's effects on anode materials remains to be revealed. To demonstrate those effects, we prepared CeO2 or BaTiO3 micropads deposited on Li4Ti5O12 epitaxial thin films. Compared with the cathodes, CeO2 micropads deposited on Li4Ti5O12 film showed the best performance at a high C-rate. Because the rate-determining step of Li4Ti5O12 epitaxial thin films is inner diffusion, reinforcing the surface electric field by the deposition of a low relative permittivity materials could promote high C-rate performance even in anode materials.