DFT Modelling of Li6SiO4Cl2 Electrolyte Material for Li-Ion Batteries

Abstract

There is significant interest in finding a promising lithium-containing oxide that can act as a solid electrolyte in a rechargeable lithium-ion battery. Li6SiO4Cl2 is a candidate electrolyte material which was recently characterized using both experimental and computational techniques. In this study, density functional theory simulation was used to examine the intrinsic defects, solution of promising isovalent and aliovalent dopants, possible reaction routes for the formation of Li6SiO4Cl2, and the feasibility of incorporating additional Li in this material. The results revealed that the O–Cl anti-site cluster was the lowest energy defect in this material. The LiCl Schottky was the second lowest energy defect process, and the Li Frenkel was higher—only by 0.06 eV—than the LiCl Schottky. The candidate dopants on the Li, Si and Cl were Na, Ge and F, respectively. Substituting Al on the Si site was an efficient way of increasing the amount of Li in this material. Incorporation of extra Li (up to three) was considered and this process was endothermic. Different chemical reaction routes were constructed and their reaction energies were calculated to predict the feasibility of the formation of Li6SiO4Cl2. The formation of Li6SiO4Cl2 from constituent elements (Li, Si O2 and Cl2) is thermodynamically feasible.