Structural and morphological characterization of lithium titanate: application to lithium batteries

M. OTERO; E.P.M. LEIVA; F. OLIVA; M. C. VALENTINUZZI; S. CHAUQUE; F. VACA CHAVEZ; D. BARRACO; G. A. MONTI

The Hague

Congreso; 67 annual metting of the international society of electrochemistry; 2016

The use of renewable energy and efficient storage systems are topics of current interest. The use of portable electronic devices has been feasible thanks to the technology of lithium-ion batteries (LIB). The energy storage at an average voltage of 3.8 V is 5 times higher than lead-acid batteries. They have the advantage of lower weight, higher energy density and faster charge and discharge rates, compared to other similar technologies. Since graphite has a fragile structure and incorporates lithium at a potential around lithium metal deposition, the use of better and safer anodes is necessary. Lithium titanate, Li4Ti5O12 (LTO), is one of the best candidates for anode materials at the moment for safer LIB because of many reasons: the lithium insertion process takes place at a higher potential than graphite, minimizing the decomposition of the solvent employed and consequently the formation of solid electrolyte interface (SEI). Also, it is a ?zero-strain? material with only a 0.2% of change in cell volume when Li+ ions are intercalated/de-intercalated. In this work, Li4Ti5O12 was synthesized by solid state reaction and the starting material had post-treated at different times of ball-milling process. The obtained materials were structural and morphologycally characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The XRD pattern reveals a face-centered cubic structure indicating that the Li+ ion can be inserted in any direction, showing an anisotropic effect that could result in an increase of the storage capacity. According to the SEM images, the post-treatment of the starting material determines the fianl size of the particles, which is important since an appropiate particle size could improve the Li+ ion insertion in the host matrix.It is known that Nuclear Magnetic Resonance (NMR) is a powerful and widely used tool to probe the structural changes that occur in electrode materials on electrochemical cycling [1,2]. Here, by NMR detailed local structural information of the LTO was obtained. Namely, LTO was characterized and the successive stages of Li ions during electrochemical insertion were compared. The static 7Li 1D NMR spectra were performed with a Bruker Avance II 300 spectrometer (Bo=7.05 T) operating at 116.64 MHz for 7Li.