Structure stability, electronic property and voltage profile of LiFe1−nNnP1−mMmO4 olivine cathode material

First-principles computational studies under density functional theory (DFT) framework were used to investigate the structural stability, conductivity and voltage profile of LiFe 1− n N n P 1− m M m O 4 (N, M = Si or S) electrode materials. It is found that the LiFeP 7/8 Si 1/8 O 4 system has the mo...

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Published inRare metals Vol. 40; no. 12; pp. 3512 - 3519
Main Authors Cui, Zhi-Hong, Lu, Xue-Feng, Luo, Jian-Hua, Guo, Xin, Xue, Hong-Tao, Tang, Fu-Ling
Format Journal Article
LanguageEnglish
Published Beijing Nonferrous Metals Society of China 01.12.2021
Springer Nature B.V
Subjects
Biomaterials
Charge density
Chemistry and Materials Science
Density functional theory
Doping
Electric potential
Electrode materials
Energy
Energy gap
First principles
Intercalation
Lithium
Materials Engineering
Materials Science
Metallic Materials
N-type semiconductors
Nanoscale Science and Technology
Olivine
Original Article
P-type semiconductors
Physical Chemistry
Structural stability
Voltage
First principles
LiFePO
Electronic properties
Energy storage materials
Battery cathode
Doping
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Summary:First-principles computational studies under density functional theory (DFT) framework were used to investigate the structural stability, conductivity and voltage profile of LiFe 1− n N n P 1− m M m O 4 (N, M = Si or S) electrode materials. It is found that the LiFeP 7/8 Si 1/8 O 4 system has the most stable structure. After doping, the band gap values of the systems decrease gradually, and LiFe 7/8 S 1/8 PO 4 system has a minimum band gap of 1.553 eV, attributed to the hybridization of the Fe-d and S-p orbital electrons. The LiFeP 7/8 S 1/8 O 4 system demonstrates the characteristic of n-type semiconductor, and other doping systems have the feature of p-type semiconductor. Charge density difference maps show that the covalent property of Si–O bond is enhanced in the LiFeP 7/8 Si 1/8 O 4 system. The average distance of Li and O atoms in the S doping systems increases from 0.21026 to 0.21486 and 0.21129 nm, respectively, indicating that doping broadens significantly the channel of Li ion de-intercalation in LiFe 7/8 S 1/8 PO 4 and LiFeP 7/8 S 1/8 O 4 . Additionally, the results of lithium intercalation potential imply that the voltages of the doping systems fall into the range of 2.23–2.86 V. Graphic abstract
ISSN:1001-0521
1867-7185
DOI:10.1007/s12598-020-01689-7