Dissertation > Excellent graduate degree dissertation topics show

Synthesis, Structure and Performance of LiFePO4/Li1.3Al 0.3Ti1.7（PO4）3 /C

Author: HeXiaoWei
Tutor: ZhouZhenTao
School: South China University of Technology
Course: Materials Physics and Chemistry
Keywords: Ion conductor Li1.3Al0.3Ti1.7 PO4 3 Doping LiFePO4 Specific capacity
CLC: TM912
Type: Master's thesis
Year: 2010
Downloads: 140
Quote: 0
Read: Download Dissertation

Abstract


Olivine-type lithium iron phosphate (LiFePO 4 ) cathode material with high specific capacity, cyclic reversibility, rich in raw materials and easy to get, cheap, high safety performance outstanding advantages, the most promising lithium ion battery cathode material (power) one. However, there are two aspects of the shortcomings hinder the industrialization process of the lithium iron phosphate. (1) the tap density is low, its volume is lower than the energy. (2) electronic conductivity and ion conduction rate was lower, resulting in lower discharge capacity, rate performance is poor. Currently, in the improvement of the LiFePO 4 of tap density and electronic conductivity has been made great progress, but little effective method to improve the ionic conductivity. The doped the Li of the ion conductor by two methods (one-step and two-step method) 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 to improve lithium iron phosphate lithium-ion conductivity and electrical properties. Preparation Conditions on the discharge characteristics and structure of the material has an important influence, the paper through a series of synthesis conditions such as sintering temperature, the ion conductor doping amount and sintering time to improve the electrical properties of the material. Obtained the following conclusions: (1) The sintering temperature, the the ion conductor doping amount of Li 1.3 Al 0.3 Ti 1.7 (PO < sub> 4 ) and sintering time on the one-step preparation of material properties and structure, but also on the properties and structure of the material obtained under the optimum conditions of the one-step further research. The results show that with the increase of the sintering temperature, the doping amount of the ion conductor, or the sintering time, the discharge capacity of the sample is increased Esen reduced; wherein the sintering temperature is 650 ° C, and the doping amount of ion conductor for the 3 wt% and sintering time of maximum discharge capacity of the material prepared in 25h, 143.3mAh / g; crystal structure analysis shows that the crystal structure of the samples obtained in the one-step optimum conditions complete; infrared spectroscopy showed that the ion conductor Li < sub> 1.3 Al 0.3, Ti , 1.7 (PO 4 ) 3 of doping has no effect on phosphate IR spectra of lithium iron; SEM and TEM morphology analysis showed that the material was mainly spherical or almost spherical particles, the particle diameter of about 60nm, reunion caking phenomenon; discharge tests show 1.0C rate discharge, discharge capacity of 122.7 mAh · g-1; After 25 cycles, 1C discharge capacity of 118.9 mAh · g-1, the capacity retention rate was 96.8%. (2) The sintering temperature, the ion conductor doping amount of Li 1.3 Al 0.3 Ti 1.7 (the PO 4 ) 3 and sintering time on the performance and structure of the materials prepared by two-step method, further research on the properties and structure of the material obtained under the optimum conditions of the two-step method. The results show that the discharge capacity of the sample with the sintering temperature, ionic conductor doping amount or increase in the sintering time, Esen increases and then decreases. Wherein the sintering temperature is 650 ° C, the ion conductor doping amount of 2 wt%, and the sintering time for 25h when it was prepared first discharge of the material than the maximum capacity, for the 157.7mAh / g. The crystal structure analysis shows that the crystal structure of the two-step method under the optimum conditions of the samples is complete; infrared spectroscopy showed that the ion conductor Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 of doping has no effect on the infrared spectra of lithium iron phosphate; SEM and TEM image analysis showed that the materials are mainly spherical or class spherical particles, the particle size of about 50nm, reunion agglomeration; discharge tests show that the the 1.0C rate discharge, the discharge capacity of 137.9 mAh g -1 ; After 25 cycles , 1C discharge capacity of 135 mAh · g -1 , the capacity retention rate of 97.9%. (3) comparative study of the structure and properties of the samples obtained under the optimum conditions for one-step and two-step method. Structure test results show no significant difference in the crystal structure, IR and morphology of the two-step and one-step sample preparation, but the two-step method of sample preparation reunion agglomeration; electrical performance tests show that the two footwork sample preparation discharge capacity than the one-step sample preparation 0.1C and 1C rate discharge conditions, the discharge capacity increased by 10% and 12.4%, respectively, the discharge platform were increased by 0.02V and 0.2V; prepared by the two-step method samples 1C and 2C loop 25 times the capacity retention rate than the one-step sample preparation 1C and 2C capacity retention rate increased by 1.1 and 0.8 percentage points.

Related Dissertations

  1. Preparation and Photocatalytic Properties for Water Decomposition of Titanate Photocatalyst,O643.36
  2. The Study of Preparation and Photocatalytic Activity of TiO2 by Electrospinning,O614.411
  3. First- principles calculations of doped anatase titanium dioxide photocatalytic properties,O643.36
  4. Preparation of One-dimensional Nano TiO2 and Study on the Decolorization of Dyeing Wastewater,TB383.1
  5. Influence of Doping Effect on Zinc Oxide by First Principles Studies,O614.241
  6. Doped Modification and Application of Titania Photocatalyst,O643.36
  7. Preparation and Properties of Crystalline Glaze for Low Temperature and Fast Firing,TQ174.65
  8. Preparation of Zeolite Doping Nano-TiO2 and Research of the Photocatalytic Properties,TB383.1
  9. Preparation and Characterization of Doped BiFeO3 Nanocrystals,TB383.1
  10. Preparation and Properties of ZnO-based Diluted Magnetic Semiconductors,TN304.21
  11. Guide lithium polymer electrolyte membrane preparation and application,TB383.2
  12. Preparation and Research Electrochemical Properties of LiFePO4 for Cathode Material of Lithium-ion Batteries,TM912
  13. Study of SiN x -Doped SbTe Phase-Change Materials for Phase-Change Random Access Memory,TP333
  14. Doped cobalt ferrite composites and their properties,TB383.1
  15. GaAlAs / GaAs photocathode assembly mechanism of material,TN304.2
  16. Typical odor substances in raw water Photocatalytic Degradation,O643.32
  17. Titanium-based metal oxide coating preparation and application of the electrodes,X703
  18. Synthesis and Characterization of ZnO Films by Ultrasonic Spray Pyrolysis,TB43
  19. Preparation and Physical Properties of Mn and Co-doped SiC Diluted Magnetic Semiconductor Films,TN304.055
  20. Study on the Hydrothermal Synthesis of Spinel-type Lithium Ion-sieve and Ni-Cr Doping,P579
  21. Fabrication of Ag~+ Doping Titania Film on 304 Stainless Steel Substrates and Anti-corrosion Properties Research,TG174.4

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