Stabilities and electronic properties of lithium titanium oxide anode material for lithium ion battery

• Published in: Journal of power sources 2012-01, Vol.198, p.318-321
• Main Authors: Yi, Ting-Feng, Xie, Ying, Zhu, Yan-Rong, Shu, J., Zhou, An-Na, Qiao, Hong-Bin
• Format: Article
• Language: English
• Subjects: Anodes; Applied sciences; Covalent bonds; Density functional theory; Direct energy conversion and energy accumulation; Ductility; Elastic constants; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electronic properties; Exact sciences and technology; Formations; Lithium titanium oxide; Lithium-ion batteries; Stability; Thermodynamics
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2011.10.014

► The formation enthalpy for LiTi 2O 4 is calculated for the first time. ► LiTi 2O 4 is mechanically stable. ► The G/ B ratio of 0.584 indicates the ductility of LiTi 2O 4 is excellent. A theoretical study of the structural, elastic and electronic properties of spinel LiTi 2O 4 anode has been performed by density functional theory (DFT) plane-wave pseudopotential method. The independent elastic constants, shear modulus ( G), bulk modulus ( B), and Young's modulus ( E) are evaluated, respectively. The results suggest that cubic LiTi 2O 4 is mechanically stable. The G/ B ratio of 0.584 indicates the ductility of LiTi 2O 4 is good. The electron density difference of LiTi 2O 4 shows that the O 2p orbits overlap effectively with Ti 3d ones, confirming the formations of strong covalent bonds between them, while Li is fully ionized in the lattice. The formation enthalpy for LiTi 2O 4 is calculated to be −2070.723 ± 1.6 kJ mol −1. The strong covalent bonds between O and Ti atoms are not only responsible for the excellent mechanical stabilities but also very crucial for the thermodynamic stability of LiTi 2O 4 compound. Furthermore, in Li 2Ti 2O 4 compound, the full occupation of 16(c) sites by Li + not only leads to a smaller C 12 value but also leads to a much larger C 44 one. Therefore, the plasticity and ductility of the Li 2Ti 2O 4 become poor in comparison to LiTi 2O 4, while the thermodynamic stability of Li 2Ti 2O 4 can be further improved after the Li + intercalation of LiTi 2O 4.