First-principles investigation of Li ion diffusion in Li2FeSiO4

• Published in: Solid state ionics 2013-10, Vol.247-248, p.8-14
• Main Authors: Araujo, Rafael B., Scheicher, Ralph H., de Almeida, J.S., Ferreira da Silva, A., Ahuja, Rajeev
• Format: Article
• Language: English
• Subjects: Batteries; DFT; Lithium diffusion
• ISSN: 0167-2738; 1872-7689; 1872-7689
• DOI: 10.1016/j.ssi.2013.05.020

We have studied the Li-ion migration and the electrochemical performance of Li2FeSiO4 in the monoclinic crystal structure with P21 symmetry and the related delithiated system LiFeSiO4. For this purpose, the framework of the density functional theory within the generalized gradient approximation in conjunction with the climbing image nudged elastic band method was used. Addition of the Hubbard term was also considered in the Kohn–Sham Hamiltonian to better model the d electrons of the metal ions in this material. The calculated activation energies for Li ion migration are found to decrease by around 20% with the Hubbard term inclusion in the chosen diffusion pathways of Li2FeSiO4. Regarding the delithiated structure, the activation energies were found to be sensitive to the Hubbard term addition, however no general behavior such as in the lithiated structure was found. Furthermore, the diffusion coefficients were calculated considering temperatures of 300K, 500K, and 700K. •Report of the influence of the Hubbard term on the magnetic states of Li2FeSiO4.•Theoretical study of the diffusion mechanisms in Li2FeSiO4.•Lithium coefficient diffusion calculation in Li2FeSiO4 for different temperatures.