Fabrication of Anatase TiO2 Nanofibers and the investigation of the Electrochemical properties work

1
Fabrication of Anatase TiO2 Nanofibers and the
investigation of the Electrochemical
properties(work in process)

• By Ke Sun

2
1General procedure for fabrication of TiO2
nanofibers by electrospinning

• 1Preparation of precursor sol
• Ti(OiPr)4 PVP Et(OH)CH3COOH
• 2Electrospinning
• The as-spun fibers should be left in
  high-humidity environment for no less than 5
  hours for the completion of hydrolysis
• 3Annealing
• 30??100 ? (30min) 100 ? ?200 ? (30min)
• 200 ? ?300 ? (30min) 300 ? ?400 ? (30min)
• 400 ? ?500 ? (30min) 500 ? (120min)

3
2The aim of this research

• --Investigating the general law by which the
  electrochemical properties of TiO2 fibers
  change with the diameters of the fibers
• --The way to change the diameters of the
  fibers Altering the concentration of the PVP
• Ti(OiPr)4 Et(OH)CH3COOH

0.25 0.3 0.35 0.4
g PVP
4
3 Characterization of annealed fibers

• 1 XRD

• 2 SAED

5
4 Morphology of annealed fibers

• 1TEM

• 2SEM(anealed)

6
5 The controlling of diameters of fibers
The diameter of fibers rises along with the
concentration of PVP
7
6 The compare of the cycling properties of
different fibers

• 1 The charging and discharging in rate 1C

8
6????

• 2 The charging and discharging in rate 3C

9
6????

• 2 The charging and discharging in rate 8C

10
7 The morphology of fibers after cycling
700-800nm
11
Summary

• 1 The diameter of the TiO2 fibers rise along with
  the concentration of PVP
• 2 The fibers with average 250nm instead of 100nm
  has the best cycling performance. This phenomenon
  indicates it is not the thinner the better for
  nanofiber thin-film to serve as electrodes for
  Lithium ion batteries. Although smaller diameter
  enhances the efficiency of diffusion of Li, the
  larger aspect ratio also gives rise to larger
  surface energy and cause the crack of the fibers
  during the electrochemical reaction.
• 3 To verify this conclusion, the research on
  thinner fibers would be tried in future work.