Dissertation > Excellent graduate degree dissertation topics show

Study on Synthesis and Performance of FeF3and LiTi2(PO4)3as Electrode Materials for Lithium-ion Batteries

Author: ZhouMeng
Tutor: LiuLi
School: Xiangtan University
Course: Physical and chemical
Keywords: Iron fluoride cobalt doping LiTi2(PO4)3 composite Lithium-ionbatteries
CLC: TM912
Type: Master's thesis
Year: 2013
Downloads: 66
Quote: 0
Read: Download Dissertation


FeF3, which based on conversion reaction, has an attractive theoretical specificcapacity of712mAh/g. But the high ionicity, large bandgap and poor electronicconductivity result in the low actual capacity and fast capacity fading, which holdback the commercial applications. The Nasicon-type LiTi2(PO43has an openthree-dimensional framework, in which Li+ions can move easily, thus has high ionconduction. However, the poor rate capability due to its low intrinsic electronicconductivity, preventing it from being widely used in large-scale applications. Thisthesis is focused on improving the electronic conductivity and electrochemicalperformance of FeF3and LiTi2(PO43, especially the rate performance.FeF3·3H2O, FeF3·0.33H2O and anhydrous FeF3were synthesized via lowtemperature liquid-phase method followed by heat-treatment at different temperatures.The results showed that FeF3·0.33H2O with orthorhombic structure had the bestelectrochemical performance. To improve their electronic conductivity, a ball millingprocess with acetylene black powders has been used to form FeF3·nH2O/C (n=3,0.33,0) nanocomposites. Though they have different crystalline structures, they canachieve the identical reversible electrochemical conversion reaction from Fe3+to Fe0in the wide voltage range of1.04.5V. FeF3·0.33H2O/C delivered an initial dischargecapacity of177.6and105.1mAh/g at0.1C and5C (1C corresponding to237mA/g)in the voltage range of2.04.5V, and the capacity retentions remain as high as83.8%and83.3%after100cycles.The Fe1-xCoxF3·0.33H2O/C (x=0,0.03,0.05,0.07) nanocomposites wereobtained by Co cation doping and ball milling with conductive acetylene blackpowders. It was found that the Co cation had been doped into the Fe site, andCo-doping significantly improved the rate capability and cycle stability.Fe0.95Co0.05F3·0.33H2O/C exhibited excellent electrochemical performance with thedischarge capacity of151.7,136.4and127.6mAh/g at rates of1C,2C and5C in thevoltage range of2.04.5V, and its capacity retentions remain as high as92.0%,92.2%and91.7%after100cycles, respectively.LiTi2(PO43/C nanocomposite was synthesized by polyethylene glycol (PEG)assisted sol-gel method at a relative low temperature followed by ball milling withacetylene black. The effect of calcination tempreture on crystal structure and properties of LiTi2(PO43was discussed in detail. The results showed that LiTi2(PO43was synthesized at850°C had the best electrochemical properties, and carbon coatingcould improve the electronic conductivity, decrease electrochemical polarization, thusinhibiting the capacity attenuation. LiTi2(PO43/C composites exhibited excellentelectrochemical performance with the maximum discharge capacity of139.9,126.4,115.8,106.0,97.1and91.3mAh/g at rates of0.1C,0.5C,1C,2C,5C and10C (1C corresponding to140mA/g) in the voltage range of1.53.5V, respectively, and thecapcity retation reached81.5%after100cycles at10C rate.

Related Dissertations

  1. The Preparation and Thermoelectric Properties of Rare Earth Subsituted Ag Composite Ca3Co4O9-Based Oxides,TQ174.1
  2. Synthesis, Structure and Properties of PBO/SWNT Composite Fibres,TQ340.64
  3. Study on Properties of Thermal Shock and Ablation Resistance for Gr/Al-Mg Composites,TB332
  4. Study on Theory and Experiment of Wire Drawing with Composite Ultrasonic Vibration,TG663
  5. Technology of Filling Clearance and Optimizing the Bonds during Ultrasonic Brazing,TG454
  6. Study of Tin Alloy Carbon Composite Used for Lithium Ion Battery,TM912.9
  7. Research on Control System and Head of 7-Axis NC Fiber Placement Machine,TG659
  8. Study on Preparation of Composite Cross-linked Modified Modified Potato Starch,TS236.9
  9. Municipal tourism land use planning environmental impact assessment,X820.3
  10. The Combined Effect of Several Environmental Factor on Fertilization, Hatching and Juvenile Growth of Nile Tilapia,S917.4
  11. Research on the Theory of the Transmission-line Metamaterials and Their Applications,O441.6
  12. Preparation and Characteration of Composite Microspheres with Dual-, Triple- Responsive Properties,O631.3
  13. Preparation, Characterization and Application of Prussian Blue Composite Nanomaterials,TB383.1
  14. Development of Functional Automotive Interior Textiles,TS106.6
  15. Nano LaFeO 3 Controllable Synthesis and TiO 2 bridged construct composite photocatalyst,O643.36
  16. Any area on the uniform design and construct,TQ460.1
  17. Study on Modification of ZnO-TiO2 Composite Catalyst and Its Photocatalytic,X703
  18. Study on the Synthesis、Preparation and Properties of Modification Phenolic Resin/NBR Composite Adhesive,TQ433
  19. Particle Size Effect of the Nickel/Silicone Rubber Conductive Composites,TB333
  20. A Study on Properties of Composite Films from Wheat Gluten and Cornstarch,TS231
  21. Develop and Performance Study of Fabrics with New Composite Yarns,TS105.1

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