Dissertation > Excellent graduate degree dissertation topics show

Study on Synthesis and Modified of LiFePO4 as Cathode Materials

Author: TuZhiGe
Tutor: ChiBo
School: Huazhong University of Science and Technology
Course: Materials Science
Keywords: lithium-ion battery LiFePO4 Heat Treatment LiFe0.98Ni0.02PO4
CLC: TM912
Type: Master's thesis
Year: 2011
Downloads: 11
Quote: 0
Read: Download Dissertation

Abstract


With the high specific capacity, low cost, environment friendly, the excellent cycling performance and the fine safety, LiFePO4 was considered to be the first alternative to as cathode material of the next generation of lithium-ion battery. However, the conductivity (electronic conductivity and ionic conductivity, the Li+ diffusion rate, and the high rate charge and discharge performances of LiFePO4 were so poor. All of the problems of LiFePO4 obstructed the way for the commercialization.Because the hydrothermal temperature and the hydrothermal time were the two most important parameters for hydrothermal reaction, LiFePO4 with good crystalline and high purity was prepared by suitable hydrothermal temperature and hydrothermal time via hydrothermal in this thesis. The performances of LiFePO4 were studied and analyzed by XRD, FSEM, and EDAX. The best crystalline and purity of LiFePO4 was got under 180℃and 3h by hydrothermal reaction. The synthesis mechanism and the growth mechanism were further investigated under the different hydrothermal temperature and the different hydrothermal temperature time.In order to improve the conductivity, the diffusion rate of Li+, and the high rate charge and discharge performance on LiFePO4, heat treatment and doping Ni were adopted.The impact of heat treatment on LiFePO4 was researched in this thesis. The optimal heat treatment temperature was determined by TG analysis. The heat treatment temperature was 900℃. The protective gas was N2. The heat treatment time was 5h.Compared with the LiFePO4 not, the LiFePO4 which was heat treated had good crystalline and small particle size by XRD, FSEM. Special groups of LiFePO4 were measured and analysis by FTIR. The reasons that the special absorption peak occurred were explained. It is clear that the PO4 group was the major polyanion part of LiFePO4. The increasing of discharge capacity and the improvement of cycling performance of LiFePO4 were got a reasonable explanation by electrochemical testing and analysis. The Li+ migration rate of LiFePO4 was calculated and the improvement of the proliferation of LiFePO4 was explained. A series of LiFe1-xNixPO4 （x = 1.0%, 2.0%, 5.0%, 10.0%, 20.0%, 30.0%, 40.0%） was prepared by hydrothermal and heat treatment in this thesis. LiFe0.98Ni0.02PO4 had the best crystalline, the highest purity and the smallest particle by XRD, FSEM and EDAX analysis. LiFe0.98Ni0.02PO4 electrochemical properties were system analyzed. It is clear that Ni doping didn’t cause the potential influence of LiFe0.98Ni0.02PO4, but Ni doping made the distortion of lattice of LiFe0.98Ni0.02PO4, and the migration paths of Li+ was unobstructed. Comparing to LiFePO4, the first discharge capacity was increased 7mAh/g and the cycle performance was better for LiFe0.98Ni0.02PO4. The diffusion coefficient of Li+ was calculated by CV analysis. Comparing to LiFePO4, the diffusion coefficient of Li+ was increased by 22.2%, and the improvement of the diffusion coefficient of Li+ of LiFePO4 was explained.

Related Dissertations

  1. Preparation and Properties of Silicon Carbon Anode for Lithium Ion Battery,TM912.9
  2. Study on the Subsurface Crack of Supporting Roller Made of Austempered Ductile Iron,TG156.3
  3. The Design and Implementation of Control System for Wire-steel Heat Treatment Direct-fired Furnace,TP273
  4. Study on the Spinnability of Semi-Aromatic Polyamide,TQ340.1
  5. Guide lithium polymer electrolyte membrane preparation and application,TB383.2
  6. Heat Treatment of Cast Al-Cu-Ti-(La) alloy microstructure and mechanical properties of,TG166.3
  7. Semi-solid / hot extruded hypereutectic Al-Fe alloy heat Mechanism,TG166.3
  8. Hot extruded Mg-Zn-Zr-Gd alloy microstructure and mechanical properties,TG379
  9. Mg-Zn alloy microstructure and mechanical properties,TG146.22
  10. Ultrasonic deposition of spray forming blank Quality,TF124.39
  11. A508-3 nuclear power transformation plasticity of steel forgings and Numerical Simulation,TL341
  12. ZG06Cr13Ni4Mo Steel Heat Treatment on Microstructure and Properties of,TG161
  13. ZA35 alloy elements Zr on Microstructure and Properties,TG131
  14. Heat Treatment on biodegradable PBST elastic fibers and degradation properties,TQ340.1
  15. TC4 alloy pulsed laser deposition of hydroxyapatite microstructure and properties of,TG146.23
  16. Based on the configuration king and Matlab trolley furnace control system design,TP277
  17. Graphite anode low temperature performance influencing factors and improving research,TM912
  18. New lithium -ion battery anode material Li 4 Ti 5 O 12 Preparation and Modification,TM912
  19. Study of the Annealing Treatments of Electrodeposited CuInSe2 and Cu（In,Ga）Se2 Thin Films,TB43
  20. The Effect of Direct Electric Resistance Heat Treatment on the Mechanical Properties of Orthodontic NiTi Archwires,R783.5

CLC: > Industrial Technology > Electrotechnical > Independent power supply technology (direct power) > Battery
© 2012 www.DissertationTopic.Net  Mobile