Ab-initio design of novel cathode material LiFeP1-xSixO4 for rechargeable Li-ion batteries. (1st August 2019)

• Record Type: Journal Article
• Authors: Yi, Sangkoan; Moon, Janghyuk; Cho, Maenghyo; Cho, Kyeongjae
• Is Part Of: Electrochimica acta. Volume 313(2019)
• Page Start: 70
• Page End: 78
• Publication Date: 2019-08-01
• Subjects: Lithium ion battery -- Ab initio method -- LiFePO4 -- LiFeP1-xSixO4; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2019.04.146
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: In this study, newly designed cathode material LiFeP1-x Six O4, with silicon mixed in LiFePO4 is investigated using the density functional theory. Its most optimized structure is the olivine structure of the Pnma space group. Bonding length show the anti-site defect which hinders Li diffusivity is prevented in the LiFeP1-x Six O4 . Lithium migration energy barriers in the (010) path of LiFeP1-x Six O4 (x = 0, 0.5, and 1) are calculated by using nudged elastic band calculations, and the average values are determined as 0.180, 0.245, and 0.280 eV for LiFePO4, LiFeP0.5 Si0.5 O4, and LiFeSiO4, respectively. This signifies that the Li ionic diffusivity is degraded thermodynamically, which is contrary to that indicates by the calculated bonding length, however, the difference is negligibly small. Furthermore, the intercalation voltage increases up to 4.97 V, depending on the Si ratio to P, and is much higher than that of the pristine cathode materials LiFePO4 (∼3.47 V) enabling voltage optimization by Si substitution. The energy density is proportional to the intercalation voltage, hence the energy density is increased, respectively. Finally, the Total density of states show that the electronic conductivity of LiFeP1-x Six O4 (x = 0–1) is better than that of LiFePO4 . Highlights: Novel cathode material LiFeP1-x Six O4 is detail designed using ab-initio study. Optimized LiFeP1-x Six O4 crystal structure is olivine structure Pnma space group. LiFeP1-x Six O4 cathode material diminishes anti-site defect and enhances electronic conductivity. LiFeP1-x Six O4 cathode material overcome low intercalation voltage and control the voltage. LiFeP1-x Six O4 cathode material improves volumetric energy density.