{"title":"通过掺杂 Na+ 提高锂离子电池用 LiMn0.6Fe0.4PO4/C 负极材料的高倍率能力和循环稳定性","authors":"Jiahao Xu, Kangwei Hou, Xiaolin Li, Yuhan Bian, Yaping Wang, Li Wang, Guangchuan Liang","doi":"10.1021/acsaem.4c01659","DOIUrl":null,"url":null,"abstract":"The practical applications of lithium manganese iron phosphate (LMFP) are severely circumvented by the inferior electronic conductivity and electrochemical reaction kinetics. In this work, a Na<sup>+</sup>-doping method is adopted to prepare Li<sub>1–<i>x</i></sub>Na<sub><i>x</i></sub>Mn<sub>0.6</sub>Fe<sub>0.4</sub>PO<sub>4</sub>/C (<i>x</i> = 0, 0.01, 0.02, 0.03) materials by spray drying combined with the carbothermal reduction method. It is found that appropriate Na<sup>+</sup> doping enhances the crystallinity, reduces Li–Fe antisite defects, decreases the primary particle size, and homogenizes the size distribution of the LMFP material. Moreover, the inferior rate and cycling performance of LMFP are mainly ascribed to the slower Li<sup>+</sup> diffusion kinetics of Mn redox. A combination of experiments and DFT calculations shows that Na<sup>+</sup> doping can increase the Li–O bond length, widen the Li<sup>+</sup> diffusion channel, and decrease Li<sup>+</sup> diffusion energy barriers, which can accelerate the Li<sup>+</sup> diffusion rate and Mn redox kinetics, thereby improving the high-rate capability and cycling stability of Na<sup>+</sup>-doped samples. Besides, doped Na<sup>+</sup> can not only act as pillars to stabilize the structure but also reduce Mn<sup>3+</sup> content and Mn–Mn interactions to alleviate the Jahn–Teller effect, which also helps to improve the cycling performance of Na<sup>+</sup>-doped samples, wherein the Li<sub>0.98</sub>Na<sub>0.02</sub>Mn<sub>0.6</sub>Fe<sub>0.4</sub>PO<sub>4</sub>/C sample exhibits optimal rate and cycling performances. Its specific discharge capacity is 125.0 mAh g<sup>–1</sup> at 5 C, and the capacity retention rate reaches 96.7% after 100 cycles at 1 C. Therefore, the Na<sup>+</sup>-doping strategy is believed to be an effective modification means to ameliorate the high-rate and cycling capabilities of olivine-based cathode materials.","PeriodicalId":4,"journal":{"name":"ACS Applied Energy Materials","volume":null,"pages":null},"PeriodicalIF":5.4000,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Enhancing the High-Rate Capability and Cycling Stability of LiMn0.6Fe0.4PO4/C Cathode Materials for Lithium-Ion Batteries by Na+ Doping\",\"authors\":\"Jiahao Xu, Kangwei Hou, Xiaolin Li, Yuhan Bian, Yaping Wang, Li Wang, Guangchuan Liang\",\"doi\":\"10.1021/acsaem.4c01659\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The practical applications of lithium manganese iron phosphate (LMFP) are severely circumvented by the inferior electronic conductivity and electrochemical reaction kinetics. In this work, a Na<sup>+</sup>-doping method is adopted to prepare Li<sub>1–<i>x</i></sub>Na<sub><i>x</i></sub>Mn<sub>0.6</sub>Fe<sub>0.4</sub>PO<sub>4</sub>/C (<i>x</i> = 0, 0.01, 0.02, 0.03) materials by spray drying combined with the carbothermal reduction method. It is found that appropriate Na<sup>+</sup> doping enhances the crystallinity, reduces Li–Fe antisite defects, decreases the primary particle size, and homogenizes the size distribution of the LMFP material. Moreover, the inferior rate and cycling performance of LMFP are mainly ascribed to the slower Li<sup>+</sup> diffusion kinetics of Mn redox. A combination of experiments and DFT calculations shows that Na<sup>+</sup> doping can increase the Li–O bond length, widen the Li<sup>+</sup> diffusion channel, and decrease Li<sup>+</sup> diffusion energy barriers, which can accelerate the Li<sup>+</sup> diffusion rate and Mn redox kinetics, thereby improving the high-rate capability and cycling stability of Na<sup>+</sup>-doped samples. Besides, doped Na<sup>+</sup> can not only act as pillars to stabilize the structure but also reduce Mn<sup>3+</sup> content and Mn–Mn interactions to alleviate the Jahn–Teller effect, which also helps to improve the cycling performance of Na<sup>+</sup>-doped samples, wherein the Li<sub>0.98</sub>Na<sub>0.02</sub>Mn<sub>0.6</sub>Fe<sub>0.4</sub>PO<sub>4</sub>/C sample exhibits optimal rate and cycling performances. Its specific discharge capacity is 125.0 mAh g<sup>–1</sup> at 5 C, and the capacity retention rate reaches 96.7% after 100 cycles at 1 C. Therefore, the Na<sup>+</sup>-doping strategy is believed to be an effective modification means to ameliorate the high-rate and cycling capabilities of olivine-based cathode materials.\",\"PeriodicalId\":4,\"journal\":{\"name\":\"ACS Applied Energy Materials\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":5.4000,\"publicationDate\":\"2024-09-13\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"ACS Applied Energy Materials\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://doi.org/10.1021/acsaem.4c01659\",\"RegionNum\":3,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Applied Energy Materials","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1021/acsaem.4c01659","RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
Enhancing the High-Rate Capability and Cycling Stability of LiMn0.6Fe0.4PO4/C Cathode Materials for Lithium-Ion Batteries by Na+ Doping
The practical applications of lithium manganese iron phosphate (LMFP) are severely circumvented by the inferior electronic conductivity and electrochemical reaction kinetics. In this work, a Na+-doping method is adopted to prepare Li1–xNaxMn0.6Fe0.4PO4/C (x = 0, 0.01, 0.02, 0.03) materials by spray drying combined with the carbothermal reduction method. It is found that appropriate Na+ doping enhances the crystallinity, reduces Li–Fe antisite defects, decreases the primary particle size, and homogenizes the size distribution of the LMFP material. Moreover, the inferior rate and cycling performance of LMFP are mainly ascribed to the slower Li+ diffusion kinetics of Mn redox. A combination of experiments and DFT calculations shows that Na+ doping can increase the Li–O bond length, widen the Li+ diffusion channel, and decrease Li+ diffusion energy barriers, which can accelerate the Li+ diffusion rate and Mn redox kinetics, thereby improving the high-rate capability and cycling stability of Na+-doped samples. Besides, doped Na+ can not only act as pillars to stabilize the structure but also reduce Mn3+ content and Mn–Mn interactions to alleviate the Jahn–Teller effect, which also helps to improve the cycling performance of Na+-doped samples, wherein the Li0.98Na0.02Mn0.6Fe0.4PO4/C sample exhibits optimal rate and cycling performances. Its specific discharge capacity is 125.0 mAh g–1 at 5 C, and the capacity retention rate reaches 96.7% after 100 cycles at 1 C. Therefore, the Na+-doping strategy is believed to be an effective modification means to ameliorate the high-rate and cycling capabilities of olivine-based cathode materials.
期刊介绍:
ACS Applied Energy Materials is an interdisciplinary journal publishing original research covering all aspects of materials, engineering, chemistry, physics and biology relevant to energy conversion and storage. The journal is devoted to reports of new and original experimental and theoretical research of an applied nature that integrate knowledge in the areas of materials, engineering, physics, bioscience, and chemistry into important energy applications.