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Detailed Program
Paper Number : FU-P02
Time Frame : 12:00~13:30
Presentation Date : Thursday, 27, November
Session Name : Fuel cells and Batteries
Session Chair 1# : -
Session Chair 2# : -
Fabrication and characterization of spherical Li3V2(PO4)3/C cathode material by hydrothermal method
Mr. Jungin Moon
PaiChai University
The Li-ion batteries have been widely used for portable electronic devices and hybrid electric vehicles because of their high energy densities. Among the known cathode materials, most commercial Li-ion secondary batteries use either LiCoO2 or LiMnO2 with layered structure. These materials are industry standard, but appear short lifetime, low energy density, expensive, and possible safety hazards. Therefore, the above mentions and the low thermal stability of Li metal oxides hinder large-scale application in electric vehicles. Currently, the monoclinic Li3V2(PO4)3 (LVP) material is of particular interest because it has good ion mobility, high operate voltage, high theoretical capacity (197 mAh g-1) and good thermal stability. However, the LVP has lower ionic conductivity due to the polarization of V–O bond, which greatly restricts its practical application for Li-ion batteries. Its lower conductance has been better solved to some extent by doping metal and coating the material with a carbon layer. Spherical Li3V2(PO4)3 (LVP) and carbon-coated LVP (LVP/C) with a monoclinic phase for the cathode materials are synthesized by a hydrothermal method using N2H4 as the reducer and saccharose as the carbon source. The structure, composition, morphology, and electro-chemical performance were compared between carbon-coated LVP and pure LVP. The results show that single phase LVP without impurity phases such as LiV(P2O7), Li(VO)(PO4) and Li3(PO4) can be obtained after calcination at 800 oC for 4 h. SEM and TEM images show that the particle sizes are 0.5–2 µm and the thickness of the amorphous carbon layer is approximately 3–4 nm. The CV curves for the test cell are recorded in the potential ranges 3.0–4.3 V and 3.0–4.8 V at a scan rate of 0.01 mV s-1 and at room temperature. At potentials between 3.0 and 4.8 V, the third Li+ ions from the LVP can be completely extracted, at voltages close to 4.51 V. Cycling tests are carried out at charge-discharge rates of 0.2 to 5 C between 3.0 and 4.3 V.
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