掺杂LiFePO_4第一性原理计算和超交换作用研究
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摘要
LiFePO_4是当前锂离子电池新一代正极材料的研究热点之一。本文采用高温固相法合成了Fe位和Li位掺杂的样品,采用XRD(X-ray radial diffraction,X射线衍射分析)、SEM(Scanning electron microscope,扫描电子显微镜观察)、充放电试验等测试手段,从合成方法、结构特征、表面形貌、电化学性能等方面进行了研究,确定了不同掺杂元素的最佳配比。
结合第一性原理计算方法,对掺杂磁性原子含量为0.25的结构进行了计算,发现掺杂磁性原子后能带结构变得复杂化,而且更密集。总的电子态密度分布基本没有变化,变化主要集中在费米能级附近的磁性原子3d轨道上,掺入的磁性原子对最近邻的Fe原子的电子分布影响比较大。
本文还进一步计算了LiFePO_4脱嵌前后的电子结构,结果表明脱嵌前后的能带结构和电子态密度存在差异,为后续对LiFePO_4材料进行系统的结构分析奠定了基础。
LiFePO_4 is promising candidates of cathode materials for lithium ion batteries. The Fe-doping and Li-doping LiFePO_4 were prepared by high temperature solid-phase synthesization. A study on the synthesis method, structure and electrochemical performance of LiFePO_4 as cathode materials for lithium ion batteries had been carried out systemically and in detail through test measures such as XRD, SEM, and CV and so on in this dissertation. The test results showed the best doping contents in the samples.
An ab initio method with pseudo potentials had been used to calculate the 0.25 doping content in the cathode material LiFePO_4 in Lithium batteries. The results showed that the band structure of doped was more complicated and dense than undoped LiFePO_4. There ware no significant changes in the total DOS. On the contrary, the changes had taken placed in the 3d orbit of the magnetic atoms at the Fermi level. The electron density distrutions of the nearest Fe atom were significantly influenced by the doping magnetic atoms.
The first-principles calculations were also performed in the FePO_4. The calculated conclusions were revealed that there were differences in the band structure and electrons density between LiFePO_4 and FePO_4. Therefore, the basis had been prepared for the deep systemic structural analysis in LiFePO_4.
结合第一性原理计算方法,对掺杂磁性原子含量为0.25的结构进行了计算,发现掺杂磁性原子后能带结构变得复杂化,而且更密集。总的电子态密度分布基本没有变化,变化主要集中在费米能级附近的磁性原子3d轨道上,掺入的磁性原子对最近邻的Fe原子的电子分布影响比较大。
本文还进一步计算了LiFePO_4脱嵌前后的电子结构,结果表明脱嵌前后的能带结构和电子态密度存在差异,为后续对LiFePO_4材料进行系统的结构分析奠定了基础。
LiFePO_4 is promising candidates of cathode materials for lithium ion batteries. The Fe-doping and Li-doping LiFePO_4 were prepared by high temperature solid-phase synthesization. A study on the synthesis method, structure and electrochemical performance of LiFePO_4 as cathode materials for lithium ion batteries had been carried out systemically and in detail through test measures such as XRD, SEM, and CV and so on in this dissertation. The test results showed the best doping contents in the samples.
An ab initio method with pseudo potentials had been used to calculate the 0.25 doping content in the cathode material LiFePO_4 in Lithium batteries. The results showed that the band structure of doped was more complicated and dense than undoped LiFePO_4. There ware no significant changes in the total DOS. On the contrary, the changes had taken placed in the 3d orbit of the magnetic atoms at the Fermi level. The electron density distrutions of the nearest Fe atom were significantly influenced by the doping magnetic atoms.
The first-principles calculations were also performed in the FePO_4. The calculated conclusions were revealed that there were differences in the band structure and electrons density between LiFePO_4 and FePO_4. Therefore, the basis had been prepared for the deep systemic structural analysis in LiFePO_4.
引文
1. Masataka W. Recent development in lithium ion battery [J], Materials Science and Engineering, 2001,33: 109-134
2. Han K N, Seo H M, Kim J K, et al. Development of a plastic Li-ion battery cell for EV applications [J], J Power Sources, 2001, 101(2): 196-200
3. Nishi Y. Lithium ion secondary batteries: Past 10 years and the future [J], J. Power Sources, 2001,100 (1-2): 101-106
4. Ceder G, Chiang Y-M, Sadoway D R, et al. Identification of cathode materials for lithium batteries guided by first-principles calculations [J], Nature (London), 1998, 392: 694-696
5. Baker J, Saidi M Y, Swoyer J L. Lithium iron( II )phospho-olivines prepared by a novel carbonthermal reduction methods [J], Electrochem. Solid-State lett, 2003, 6(3): A53-A55
6. Kohn W. Nobel lecture: electronic structure of matter -wave functions and density functional [J], Rev. Mod. Phys. 1999, 71: 1253-1266
7. Dreizler R M, Gross E K U. Density Functional Theory[M]. Berlin: Springer-Vertag,1990
8. Pickett W E, Singh D J. Magneto electronic and Magneto structural Coupling in the La_(1-x)Ca_xMnO_3 System [J], Europhys. Lett, 1995, 32(9): 759-764
9. Satpathy S, Popovic Z S, Vukajlovic F R. Electronic structure of the perovskite oxides:La_(1-x)Ca_xMnO_3 [J], Phys. Rev. Lett., 1996, 76: 960-963
10. Van Der Ven A, Aydinol M K, Ceder G, et al. First-principles investigation of phase stability in Li_xCoO_2 [J], Phys. Rev. B, 1998, 58: 2975-2987
11. Shi S Q, Wang D S, Meng S, et al. First-Principles studies on cation-doped spinel LiMn_2O_4 for lithium ion batteries [J], Phys. Rev. B, 2003, 67: 115130
12. Jin S, Tiefel T H. McCormack M, et al. Thousandfold change in resistivity in magnetoresistive La-Ca-Mn-O films [J], Science, 1994, 264(5157): 413-415
13. Sarma D D, Shanthi N, Barman S R, et al. Band theory for ground-state properties and excitation spectra of perovskite LaMO_3(M=Mn,Fe,Co,Ni) [J], Phys Rev Lett., 1995, 75:1126-1129
14. Solovyev I, Hamada N. Terakura K. Crucial role of the lattice distortion in the magnetism of LaMnO_3 [J], Phys. Rev. Lett., 1996, 76: 4825-4828
15. Pickett W E, Singh D J. Electronic structure and half-metallic transport in the La_(1-x)Ca_xMnO_3 system [J], Phys. Rev. B, 1996, 53: 1146-1160
16. Winter M, Besenhard J O, Spahr M E, et al. Insertion electrode materials for rechargeable lithium batteries [J], Advanced Materials, 10(10): 725-763
17. Mizushima K, Jones P C, Wiseman P J, et al. Li_xCoO_2(0
18. Reimers J N, Dahn J R. Electrochemical and in situ X-ray diffraction studies of lithium intercalation in Li_xCoO_2 [J], Electrochem. Soc. 139: 2091-2097
19. Ohzuku T, Ueda A. J A. Solid-state redox reactions of LiCoO_2 (R_(3m))for 4 volt stecondary lithium cells[J], Electrochem.Soc, 1994, 141: 2972-2978
20. Li W, Currie J C.Morphology effects on the electrochemical performance of LiCo_(1-x)Ni_xO_2 [J], J.Electrochem Soc, 1997, 144(8): 2773-2779
21. Yamada A, Kudo Y, Liu K Y. Reaction mechanism of the olivine-type Li_x(Mn_(0.6)Fe_(0.4)) PO_4(0≤x≤1) [J], J. Electrochem. Soc, 2001,148(7): A747-A754
22. Andersson A S, Thomas J O, Kalska B, et al. Thermal Stability of LiFePO_4-Based Cathodes [J], Electrochem. Solid State Lett, 2000, 3(2): 66-68
23. Yamada A, Chung S C. Optimized LiFePO_4 for Lithium Battery Cathodes [J],J.Electrochem. Soc, 2001, 148(3): A224-A229
24. Chung S Y, Bloking J T, Chiang Y-M. Electronically conductive phospho-olivine as lithium storage electrodes [J], Nat. Mater, 2002, 1: 123-128
25. Shi S Q , Liu L J, Ouyang C Y ,et al. Enhancement of electronic conductivity of LiFePO_4 by Cr doping and its identification by first-principles calculations [J], Phys. Rev. B, 2003,68:195108
26. Wang D, Li H, Shi S , et al. Improving the rate performance of LiFePO_4 by Fe-site doping [J], Electrochimica Acta, 2005, 50: 2955-2958
27. Rousse G, Carvajal J R, Patoux S, et al. Magnetic structures of the triphylite LiFePO_4 and of its delithiated form FePO_4 [J], Chem. Mater., 2003, 15: 4082-4090
28. Shi S Q , Ouyang C Y , Xiong Z H , et al. First-principles investigation of the structural, magnetic, and electronic properties of olivine LiFePO_4 [J], Phys. Rev. B, 2005, 71:144404.
29. Tang P, Holzwarth N A W. Electronic structure of FePO_4, LiFePO_4, and related materials [J], Phys. Rev. B, 2003, 68: 165107
30. 姜寿亭,李卫.凝聚态磁性物理[M].北京:科学出版社, 2003, 35-36
31. Yamada A, Chung S C. Crystal Chemistry of the Olivine-Type Li(Mn_yFe_(1-y))PO_4 and (Mn_yFe_(1-y))PO_4 as Possible 4 V Cathode Materials for Lithium Batteries [J], J.Electrochem. Soc, 2001, 148(8): A960-A967
32. Tarascon J M, Armand M. Issues and challenges facing rechargeable lithium bateries [J],Nature, 2001,414:359-367
33. Padhi A K, Nanjundawawy K S, Goodenough J B. Effect of structure on the Fe~(3+)/Fe~(2+) redox couple in iron phosphates [J], J Electrochem Soc, 1997,144(5): 1609-1613
34. Hunt A, Ching W-Y, Chiang Y-M, et al. Electronic structures of LiFePO_4 and FePO_4 studied using resonant inelastic x-ray scattering [J], Phys. Rev. B, 2006, 73: 205120
35. Zhou F, Kang K, Maxisch T, et al. The electronic structure and band gap of LiFePO_4 and LiMnPO_4 [J], Solid State Commun, 2004,132: 181-186
36. Zhou F, Marianetti C A, Cococcioni M, et al. Phase separation in Li_xFePO_4 induced by correlation effects [J], Phys. Rev. B, 2004, 69: 201101(R)
37. Xu Y-N, Chung S-Y, Bloking J T, et al. Electronic structure and electrical conductivity of undoped LiFePO_4 [J], Electrochemical and Solid-State Letters,2004, 7(6): A131-A134
38. Zhou F, Cococcioni M, Marianetti C A , et al. First-principles prediction of redox potentials in transition-metal compounds with LDA+U [J], Phys. Rev. B, 2004, 70:235121
39. Ravet N, Abouimrane A, Armand M. On the electronic conductivity of phospho-olivines as lithium storage electrodes [J], Nat. Mater., 2003,2, 702:3
40. Maxisch T, Zhou F, Ceder G. Ab Initio Study of the Migration of Small Polarons in Olivine Li_xFePO_4 and their Association with Lithium Ions and Vacancies [J], Phys. Rev.B,2006,73:104301
41. Ouyang C Y, Shi S Q, Chen L Q, et al. First principles study of Li ion diffusion in LiFePO_4 [J], Phys. Rev. B, 2004, 69: 104303
42.Deb A,Bergmann U.Cairns E J,et al.Structural Investigations of LiFePO_4 Electrodes by Fe[J],Phys.Chem.B.108.12-Mar.,2004:7046-7051
43.Penazzi N,Arrabito M,Piana M,et al.Mixed lithium phosphates as cathode materials for Li-Ion cells[J],Journal of the European Ceramic Society,2004(24):1381-1384
44.王恩通,刘根庆,任引哲.锂离子电池正极材料LiFePO_4在Fe位掺杂的研究进展[J],化学研究,2007,18(1):93-97
45.Huang H,Yin S C,Nazar L F.Approaching theoretical capacity of LiFePO_4 at room temperature at high rates[J],Electrochem.Solid-State Lett.,2001,4(10):A170-A172
46.Prosini P P,Carewska M,Scaccia S,et al.A new synthetic route for preparing LiFePO_4with enhanced electrochemical performance[J],Journal of the Electrochemical Society,2002,149(7):A886-A890
47.吴宇平,万春荣,姜长印.锂离子二次电池[M].北京:化学工业出版社,2002,57
48.王晓琼,李新海,王志兴等.LiFePO_4掺镍的改性研究[J],电池,2005,35(5):371-373
49.胡成林,代建清,戴永年等.Ti离子掺杂对LiFePO_4材料性能的影响[J],材料导报,2007,21(7):147-149
50.马礼敦.近代X射线多晶体衍射-实验技术与数据分析[M].北京:化学工业出版社,2004
51.Padhi A K,Nanjundaswamy K S,Goodenough J B.Phospho-olivines as positive electrode materials for rechargeable lithium battery[J],J Electrochem Soc,1997,144(4):1188
52.甘晖.LiFePO_4/C的合成及表征及电化学性能研究[D].福州:福建师范大学,2003
53.陈学军,赵新兵等.一步固相合成Nb掺杂LiFePO_4/C及其电化学性能[J],中国有色金属学报,2006,16(10):1665-1671
54.Strel'tsov V A,Belokoneva E L,Tsirel'son,et al.Multipole analysis of the electron density in triphylite LiFePO_4 using X-ray diffraction data[J],Acta Crystallographica B (39,1983-1993),49:147-153
55.阎守胜.固体物理基础[M].北京:北京大学出版社,2002:150-200
56.R.霍夫曼.固体与表面[M].北京:化学工业出版社,1996:1-56
57.Amatucci G G,Tarascon J M,Klein L C,CoO_2,the end member of the Li_xCoO_2 solid solution[J],J.Electrochem.Soc.,1996:1114-1123
58.黄祖飞.LiMnO_2体系结构与性能的第一性原理研究[D],吉林:吉林大学,2006
59.Andersson A S,Kalska B,Haggstrom L,et al.Lithium extraction/insertion in LiFePO_4:an X-ray diffraction and Mossbauer spectroscopy study[J],Solid State Ionics,2000,130:41-52
2. Han K N, Seo H M, Kim J K, et al. Development of a plastic Li-ion battery cell for EV applications [J], J Power Sources, 2001, 101(2): 196-200
3. Nishi Y. Lithium ion secondary batteries: Past 10 years and the future [J], J. Power Sources, 2001,100 (1-2): 101-106
4. Ceder G, Chiang Y-M, Sadoway D R, et al. Identification of cathode materials for lithium batteries guided by first-principles calculations [J], Nature (London), 1998, 392: 694-696
5. Baker J, Saidi M Y, Swoyer J L. Lithium iron( II )phospho-olivines prepared by a novel carbonthermal reduction methods [J], Electrochem. Solid-State lett, 2003, 6(3): A53-A55
6. Kohn W. Nobel lecture: electronic structure of matter -wave functions and density functional [J], Rev. Mod. Phys. 1999, 71: 1253-1266
7. Dreizler R M, Gross E K U. Density Functional Theory[M]. Berlin: Springer-Vertag,1990
8. Pickett W E, Singh D J. Magneto electronic and Magneto structural Coupling in the La_(1-x)Ca_xMnO_3 System [J], Europhys. Lett, 1995, 32(9): 759-764
9. Satpathy S, Popovic Z S, Vukajlovic F R. Electronic structure of the perovskite oxides:La_(1-x)Ca_xMnO_3 [J], Phys. Rev. Lett., 1996, 76: 960-963
10. Van Der Ven A, Aydinol M K, Ceder G, et al. First-principles investigation of phase stability in Li_xCoO_2 [J], Phys. Rev. B, 1998, 58: 2975-2987
11. Shi S Q, Wang D S, Meng S, et al. First-Principles studies on cation-doped spinel LiMn_2O_4 for lithium ion batteries [J], Phys. Rev. B, 2003, 67: 115130
12. Jin S, Tiefel T H. McCormack M, et al. Thousandfold change in resistivity in magnetoresistive La-Ca-Mn-O films [J], Science, 1994, 264(5157): 413-415
13. Sarma D D, Shanthi N, Barman S R, et al. Band theory for ground-state properties and excitation spectra of perovskite LaMO_3(M=Mn,Fe,Co,Ni) [J], Phys Rev Lett., 1995, 75:1126-1129
14. Solovyev I, Hamada N. Terakura K. Crucial role of the lattice distortion in the magnetism of LaMnO_3 [J], Phys. Rev. Lett., 1996, 76: 4825-4828
15. Pickett W E, Singh D J. Electronic structure and half-metallic transport in the La_(1-x)Ca_xMnO_3 system [J], Phys. Rev. B, 1996, 53: 1146-1160
16. Winter M, Besenhard J O, Spahr M E, et al. Insertion electrode materials for rechargeable lithium batteries [J], Advanced Materials, 10(10): 725-763
17. Mizushima K, Jones P C, Wiseman P J, et al. Li_xCoO_2(0
18. Reimers J N, Dahn J R. Electrochemical and in situ X-ray diffraction studies of lithium intercalation in Li_xCoO_2 [J], Electrochem. Soc. 139: 2091-2097
19. Ohzuku T, Ueda A. J A. Solid-state redox reactions of LiCoO_2 (R_(3m))for 4 volt stecondary lithium cells[J], Electrochem.Soc, 1994, 141: 2972-2978
20. Li W, Currie J C.Morphology effects on the electrochemical performance of LiCo_(1-x)Ni_xO_2 [J], J.Electrochem Soc, 1997, 144(8): 2773-2779
21. Yamada A, Kudo Y, Liu K Y. Reaction mechanism of the olivine-type Li_x(Mn_(0.6)Fe_(0.4)) PO_4(0≤x≤1) [J], J. Electrochem. Soc, 2001,148(7): A747-A754
22. Andersson A S, Thomas J O, Kalska B, et al. Thermal Stability of LiFePO_4-Based Cathodes [J], Electrochem. Solid State Lett, 2000, 3(2): 66-68
23. Yamada A, Chung S C. Optimized LiFePO_4 for Lithium Battery Cathodes [J],J.Electrochem. Soc, 2001, 148(3): A224-A229
24. Chung S Y, Bloking J T, Chiang Y-M. Electronically conductive phospho-olivine as lithium storage electrodes [J], Nat. Mater, 2002, 1: 123-128
25. Shi S Q , Liu L J, Ouyang C Y ,et al. Enhancement of electronic conductivity of LiFePO_4 by Cr doping and its identification by first-principles calculations [J], Phys. Rev. B, 2003,68:195108
26. Wang D, Li H, Shi S , et al. Improving the rate performance of LiFePO_4 by Fe-site doping [J], Electrochimica Acta, 2005, 50: 2955-2958
27. Rousse G, Carvajal J R, Patoux S, et al. Magnetic structures of the triphylite LiFePO_4 and of its delithiated form FePO_4 [J], Chem. Mater., 2003, 15: 4082-4090
28. Shi S Q , Ouyang C Y , Xiong Z H , et al. First-principles investigation of the structural, magnetic, and electronic properties of olivine LiFePO_4 [J], Phys. Rev. B, 2005, 71:144404.
29. Tang P, Holzwarth N A W. Electronic structure of FePO_4, LiFePO_4, and related materials [J], Phys. Rev. B, 2003, 68: 165107
30. 姜寿亭,李卫.凝聚态磁性物理[M].北京:科学出版社, 2003, 35-36
31. Yamada A, Chung S C. Crystal Chemistry of the Olivine-Type Li(Mn_yFe_(1-y))PO_4 and (Mn_yFe_(1-y))PO_4 as Possible 4 V Cathode Materials for Lithium Batteries [J], J.Electrochem. Soc, 2001, 148(8): A960-A967
32. Tarascon J M, Armand M. Issues and challenges facing rechargeable lithium bateries [J],Nature, 2001,414:359-367
33. Padhi A K, Nanjundawawy K S, Goodenough J B. Effect of structure on the Fe~(3+)/Fe~(2+) redox couple in iron phosphates [J], J Electrochem Soc, 1997,144(5): 1609-1613
34. Hunt A, Ching W-Y, Chiang Y-M, et al. Electronic structures of LiFePO_4 and FePO_4 studied using resonant inelastic x-ray scattering [J], Phys. Rev. B, 2006, 73: 205120
35. Zhou F, Kang K, Maxisch T, et al. The electronic structure and band gap of LiFePO_4 and LiMnPO_4 [J], Solid State Commun, 2004,132: 181-186
36. Zhou F, Marianetti C A, Cococcioni M, et al. Phase separation in Li_xFePO_4 induced by correlation effects [J], Phys. Rev. B, 2004, 69: 201101(R)
37. Xu Y-N, Chung S-Y, Bloking J T, et al. Electronic structure and electrical conductivity of undoped LiFePO_4 [J], Electrochemical and Solid-State Letters,2004, 7(6): A131-A134
38. Zhou F, Cococcioni M, Marianetti C A , et al. First-principles prediction of redox potentials in transition-metal compounds with LDA+U [J], Phys. Rev. B, 2004, 70:235121
39. Ravet N, Abouimrane A, Armand M. On the electronic conductivity of phospho-olivines as lithium storage electrodes [J], Nat. Mater., 2003,2, 702:3
40. Maxisch T, Zhou F, Ceder G. Ab Initio Study of the Migration of Small Polarons in Olivine Li_xFePO_4 and their Association with Lithium Ions and Vacancies [J], Phys. Rev.B,2006,73:104301
41. Ouyang C Y, Shi S Q, Chen L Q, et al. First principles study of Li ion diffusion in LiFePO_4 [J], Phys. Rev. B, 2004, 69: 104303
42.Deb A,Bergmann U.Cairns E J,et al.Structural Investigations of LiFePO_4 Electrodes by Fe[J],Phys.Chem.B.108.12-Mar.,2004:7046-7051
43.Penazzi N,Arrabito M,Piana M,et al.Mixed lithium phosphates as cathode materials for Li-Ion cells[J],Journal of the European Ceramic Society,2004(24):1381-1384
44.王恩通,刘根庆,任引哲.锂离子电池正极材料LiFePO_4在Fe位掺杂的研究进展[J],化学研究,2007,18(1):93-97
45.Huang H,Yin S C,Nazar L F.Approaching theoretical capacity of LiFePO_4 at room temperature at high rates[J],Electrochem.Solid-State Lett.,2001,4(10):A170-A172
46.Prosini P P,Carewska M,Scaccia S,et al.A new synthetic route for preparing LiFePO_4with enhanced electrochemical performance[J],Journal of the Electrochemical Society,2002,149(7):A886-A890
47.吴宇平,万春荣,姜长印.锂离子二次电池[M].北京:化学工业出版社,2002,57
48.王晓琼,李新海,王志兴等.LiFePO_4掺镍的改性研究[J],电池,2005,35(5):371-373
49.胡成林,代建清,戴永年等.Ti离子掺杂对LiFePO_4材料性能的影响[J],材料导报,2007,21(7):147-149
50.马礼敦.近代X射线多晶体衍射-实验技术与数据分析[M].北京:化学工业出版社,2004
51.Padhi A K,Nanjundaswamy K S,Goodenough J B.Phospho-olivines as positive electrode materials for rechargeable lithium battery[J],J Electrochem Soc,1997,144(4):1188
52.甘晖.LiFePO_4/C的合成及表征及电化学性能研究[D].福州:福建师范大学,2003
53.陈学军,赵新兵等.一步固相合成Nb掺杂LiFePO_4/C及其电化学性能[J],中国有色金属学报,2006,16(10):1665-1671
54.Strel'tsov V A,Belokoneva E L,Tsirel'son,et al.Multipole analysis of the electron density in triphylite LiFePO_4 using X-ray diffraction data[J],Acta Crystallographica B (39,1983-1993),49:147-153
55.阎守胜.固体物理基础[M].北京:北京大学出版社,2002:150-200
56.R.霍夫曼.固体与表面[M].北京:化学工业出版社,1996:1-56
57.Amatucci G G,Tarascon J M,Klein L C,CoO_2,the end member of the Li_xCoO_2 solid solution[J],J.Electrochem.Soc.,1996:1114-1123
58.黄祖飞.LiMnO_2体系结构与性能的第一性原理研究[D],吉林:吉林大学,2006
59.Andersson A S,Kalska B,Haggstrom L,et al.Lithium extraction/insertion in LiFePO_4:an X-ray diffraction and Mossbauer spectroscopy study[J],Solid State Ionics,2000,130:41-52