Effects of doping on electronic structure and ion diffusion of Li <sub>2</sub> FeSiO <sub>4</sub>
Jianan Wang, Zhiqiang Li, YongZheng Zhu, Yao Liang, Yan Cui, Hualong Tao, Bo Song, А. И. Никифоров, Zhihua Zhang
Abstract
Abstract First‐principles calculations were performed to study the crystal structure, electronic structure, and ion diffusion of sulfur‐doped Li 2 FeSiO 4 . The sulfur atoms preferred to substitute oxygen atoms around different iron atoms and the most stable configurations were chosen for each Li 16 Fe 8 Si 8 O 32‐ x S x ( x = 1, 2, 3, 4) system to study the influence of sulfur concentration. Moreover, the configuration of the Li 16 Fe 8 Si 8 O 29 S 3 had the least band gap (2.456 eV), which indicated the best electronic conductivity. The results of mean square displacement confirmed that lithium ions could diffuse in a two‐dimensional path in Li 2 FeSiO 4 and S‐doped Li 2 FeSiO 4 along the a ‐axis and c ‐axis. Doping sulfur was able to reduce the energy barrier for diffusion to improve the diffusion of lithium ions. The diffusion coefficient of lithium‐ion was 8 orders of magnitude larger and the diffusion rate was 7 orders of magnitude larger than that of the intrinsic system at most.