Characterization of Nano-Sized Epitaxial Li4Ti5O12(110) Film Electrode for Lithium Batteries

Electrochemical properties and structure changes of nano-sized Li4Ti5O12 during lithium (de)intercalation were investigated using a two-dimensional thin film electrode. Li4Ti5O12 thin films were deposited on a Nb:SrTiO3(110) substrate by a pulsed laser deposition technique. X-ray diffraction and reflectometry measurements confirmed the epitaxial growth of 27.6-nm-thick Li4Ti5O12(110) films. Galvanostatic charge-discharge curves showed a large discharge capacity of 217 mAh g−1 at the initial discharge cycle, although the reversible capacity decreased in subsequent cycles. In situ X-ray diffraction measurements clarified the drastic structural changes of the Li4Ti5O12 film upon soaking in the electrolyte and during the first intercalation and deintercalation processes. The surface region of Li4Ti5O12 had a different structure from the bulk during electrochemical cycling and could cause the nano-sized Li4Ti5O12 electrodes to have high capacities and poor stabilities.