Electronic Properties of LiLaTiO4 Compound

Abstract

Solid Electrolytes (SEs) are materials containing charges and ions, which are known as ionic conductions. This feature is different with materials such as semiconductor or metals, where electrons or charges is transported alone [1]. SEs possess potential safety solutions compared to those that result from flammable liquid electrolyte components. Furthermore, significant advantages of SEs such as wide electrochemical windows and flexible temperature ranges make certain attention of researchers. On the other hand, low conductivity in 3D compounds needs to improve further. There are many SEs compounds used as electrolytes in batteries; however, compounds of lithium-ion are the most widely used, especially, compounds with transition metal and rare-earth elements of lithium-ion are new compounds that are researched recently. In which, transition metal and rare earth are groups of elements possessing valence electrons distributed in orbitals d or f. The transition metal is a collection of elements that are arranged mostly right between the rows on the table, from the group (IIIB) with column 3 on the left side to the group (IIB) with column 12 on the right-side periodic table of elements. These elements have valence electrons in the two outermost shells that can participate in the form of chemical bondings [2]. Besides, the rare-earth elements contain 15 Lanthanide elements in the periodic table, from atomic number Z = 57 (Lanthanum – La) to Z = 71 (Lutetium – Lu) and Scandium – Sc (Z = 21) & Yttrium – Y (Z = 39) in group IIIB, they are called because most of these elements were separated from minerals as oxides around the 18th and 19th centuries. Because of their reactivity, these rare earth elements are difficult to refine into pure metals. Also, separation procedures were not developed until the 20th century due to the similarity in chemical properties of rare-earth elements [3]. With the lithium- and/or oxygen-based main-stream materials such as single-element crystal, binary and ternary compounds, the quaternary LiLaTiO4 compound includes rare-earth element lanthanum (La) and transition metal element titanium (Ti) that have unique electronic properties due to the interaction between the f-orbital of the rare-earth and the d-orbital of the transition metal elements. Therefore, the quaternary LiLaTiO4 compound is a candidate for solid electrolytes materials of lithium-ion batteries. The geometric structure as well as the electron properties of LiLaTiO4 which have been calculated by the first-principles calculation will be presented and discussed in this chapter.