{"title":"共掺杂 LIFex-1MxPyNy-1O4(M=Co/Mn,NS/Si)锂离子电池正极材料的电子结构和锂离子扩散特性的第一性原理研究","authors":"","doi":"10.1016/j.micrna.2024.207988","DOIUrl":null,"url":null,"abstract":"<div><p>In this work, a first-principles method based on density functional theory was systematically employed to investigate the stability, electronic properties, lithium-ion migration rates, and capacity-voltage curves of the LiFe<sub>x-1</sub>M<sub>x</sub>P<sub>y</sub>N<sub>y-1</sub>O<sub>4</sub> (M = Co/Mn, N<img>S/Si) system. The results indicate that the lattice constants of the LiFe<sub>x-1</sub>M<sub>x</sub>P<sub>y</sub>N<sub>y-1</sub>O<sub>4</sub> (M = Co/Mn, N<img>S/Si) system show little variation, and the system exhibits low formation and binding energies. Among the investigated systems, LFP-Mn/S demonstrates the best structural and thermodynamic stability. The bandgap of the doped systems decreases, leading to enhanced electronic conductivity. The LiFe<sub>0.875</sub>Co<sub>0.125</sub>P<sub>0.875</sub>Si<sub>0.125</sub>O<sub>4</sub> and LiFe<sub>0.875</sub>Mn<sub>0.125</sub>P<sub>0.875</sub>Si<sub>0.125</sub>O<sub>4</sub> systems remain semiconductors, while the LiFe<sub>0.875</sub>Co<sub>0.125</sub>P<sub>0.875</sub>S<sub>0.125</sub>O<sub>4</sub> and LiFe<sub>0.875</sub>Mn<sub>0.125</sub>P<sub>0.875</sub>S<sub>0.125</sub>O<sub>4</sub> systems exhibit semi-metallic properties due to the introduction of sulfur. Differential charge density calculations reveal changes in the covalent bond strength of the doped systems, with the introduction of Si and S respectively increasing and decreasing the covalency of their bonds with surrounding oxygen atoms. Additionally, doping reduces the Li-ion diffusion energy barriers, with the LiFe<sub>0.875</sub>Co<sub>0.125</sub>P<sub>0.875</sub>Si<sub>0.125</sub>O<sub>4</sub> system exhibiting the lowest migration energy barrier. The Li-ion diffusion rate is four orders of magnitude faster than that of the intrinsic system. This is attributed to changes in the average lengths of Li–O, Co–O, and Fe–O bonds. Finally, doping also alters the de-lithiation voltage, with values ranging from 2.69 V to 3.65 V for the doped systems, and the LiFe<sub>0.875</sub>Co<sub>0.125</sub>P<sub>0.875</sub>Si<sub>0.125</sub>O<sub>4</sub> system shows the highest complete de-lithiation voltage of 3.65 V. The overall performance improvements of the doped system have significant implications for enhancing the performance of Li-ion batteries.</p></div>","PeriodicalId":100923,"journal":{"name":"Micro and Nanostructures","volume":null,"pages":null},"PeriodicalIF":2.7000,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"First principles study of the electronic structure and Li-ion diffusion properties of co-doped LIFex-1MxPyNy-1O4 (M=Co/Mn, NS/Si) Li-ion battery cathode materials\",\"authors\":\"\",\"doi\":\"10.1016/j.micrna.2024.207988\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>In this work, a first-principles method based on density functional theory was systematically employed to investigate the stability, electronic properties, lithium-ion migration rates, and capacity-voltage curves of the LiFe<sub>x-1</sub>M<sub>x</sub>P<sub>y</sub>N<sub>y-1</sub>O<sub>4</sub> (M = Co/Mn, N<img>S/Si) system. The results indicate that the lattice constants of the LiFe<sub>x-1</sub>M<sub>x</sub>P<sub>y</sub>N<sub>y-1</sub>O<sub>4</sub> (M = Co/Mn, N<img>S/Si) system show little variation, and the system exhibits low formation and binding energies. Among the investigated systems, LFP-Mn/S demonstrates the best structural and thermodynamic stability. The bandgap of the doped systems decreases, leading to enhanced electronic conductivity. The LiFe<sub>0.875</sub>Co<sub>0.125</sub>P<sub>0.875</sub>Si<sub>0.125</sub>O<sub>4</sub> and LiFe<sub>0.875</sub>Mn<sub>0.125</sub>P<sub>0.875</sub>Si<sub>0.125</sub>O<sub>4</sub> systems remain semiconductors, while the LiFe<sub>0.875</sub>Co<sub>0.125</sub>P<sub>0.875</sub>S<sub>0.125</sub>O<sub>4</sub> and LiFe<sub>0.875</sub>Mn<sub>0.125</sub>P<sub>0.875</sub>S<sub>0.125</sub>O<sub>4</sub> systems exhibit semi-metallic properties due to the introduction of sulfur. Differential charge density calculations reveal changes in the covalent bond strength of the doped systems, with the introduction of Si and S respectively increasing and decreasing the covalency of their bonds with surrounding oxygen atoms. Additionally, doping reduces the Li-ion diffusion energy barriers, with the LiFe<sub>0.875</sub>Co<sub>0.125</sub>P<sub>0.875</sub>Si<sub>0.125</sub>O<sub>4</sub> system exhibiting the lowest migration energy barrier. The Li-ion diffusion rate is four orders of magnitude faster than that of the intrinsic system. This is attributed to changes in the average lengths of Li–O, Co–O, and Fe–O bonds. Finally, doping also alters the de-lithiation voltage, with values ranging from 2.69 V to 3.65 V for the doped systems, and the LiFe<sub>0.875</sub>Co<sub>0.125</sub>P<sub>0.875</sub>Si<sub>0.125</sub>O<sub>4</sub> system shows the highest complete de-lithiation voltage of 3.65 V. The overall performance improvements of the doped system have significant implications for enhancing the performance of Li-ion batteries.</p></div>\",\"PeriodicalId\":100923,\"journal\":{\"name\":\"Micro and Nanostructures\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.7000,\"publicationDate\":\"2024-09-11\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Micro and Nanostructures\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S2773012324002371\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"PHYSICS, CONDENSED MATTER\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Micro and Nanostructures","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2773012324002371","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"PHYSICS, CONDENSED MATTER","Score":null,"Total":0}
First principles study of the electronic structure and Li-ion diffusion properties of co-doped LIFex-1MxPyNy-1O4 (M=Co/Mn, NS/Si) Li-ion battery cathode materials
In this work, a first-principles method based on density functional theory was systematically employed to investigate the stability, electronic properties, lithium-ion migration rates, and capacity-voltage curves of the LiFex-1MxPyNy-1O4 (M = Co/Mn, NS/Si) system. The results indicate that the lattice constants of the LiFex-1MxPyNy-1O4 (M = Co/Mn, NS/Si) system show little variation, and the system exhibits low formation and binding energies. Among the investigated systems, LFP-Mn/S demonstrates the best structural and thermodynamic stability. The bandgap of the doped systems decreases, leading to enhanced electronic conductivity. The LiFe0.875Co0.125P0.875Si0.125O4 and LiFe0.875Mn0.125P0.875Si0.125O4 systems remain semiconductors, while the LiFe0.875Co0.125P0.875S0.125O4 and LiFe0.875Mn0.125P0.875S0.125O4 systems exhibit semi-metallic properties due to the introduction of sulfur. Differential charge density calculations reveal changes in the covalent bond strength of the doped systems, with the introduction of Si and S respectively increasing and decreasing the covalency of their bonds with surrounding oxygen atoms. Additionally, doping reduces the Li-ion diffusion energy barriers, with the LiFe0.875Co0.125P0.875Si0.125O4 system exhibiting the lowest migration energy barrier. The Li-ion diffusion rate is four orders of magnitude faster than that of the intrinsic system. This is attributed to changes in the average lengths of Li–O, Co–O, and Fe–O bonds. Finally, doping also alters the de-lithiation voltage, with values ranging from 2.69 V to 3.65 V for the doped systems, and the LiFe0.875Co0.125P0.875Si0.125O4 system shows the highest complete de-lithiation voltage of 3.65 V. The overall performance improvements of the doped system have significant implications for enhancing the performance of Li-ion batteries.