| Summary: | Improving electrical conductivity of LiFePO4 as cathode material for secondary
lithium battery had been reached by employing carbon coating and TiO2 doping.
Synthesis and the coating process are conducted in two stages of heating by the
sol-gel method. The starting materials for forming of LiFePO4 are the powder of
Li2CO3, NH4H2PO4 and FeC2O4.H2O. Citric Acid and Polyetyleneglycol are used
as the agent for creating porosity in active cathode material LiFePO4. Beside that,
Citric Acid is also used as the carbon source for LiFe1-xTixPO4/C. Meanwhile
Titanium dioxide is used as the doping element. Applied temperature of the
synthesis prosess and amount of doping element are varied, respectively 700, 800
and 900°C for 12 hours and 0, 2 and 4 % wt TiO2. Temperature and time of
carbon coating process is fixed at 700°C for 10 hour, amount of carbon coating is
4 wt %. This is done to observe their effects on the electrical conductivity of the
cathode material. The phase composition of the synthesized active material is
analyzed by XRD. This analysis indicates that the expected phase was formed as
LiFePO4. Ti ions were sufficiently doped in LiFePO4 and did not alter its crystal
structure. The morphology and distribution of carbon in the material LiFe1-
xTixPO4/C were analyzed by SEM/EDX. Increasing the synthesis temperature will
increase the particle size and create less porosity. It was decreased the electrical
conductivity of LiFe1-xTixPO4/C. Electrical conductivity of LiFe1-xTixPO4/C was
tested by the Electrochemichal Impedance Spectroscopy (EIS). This test showed
that the electrical conductivity of LiFe1-xTixPO4/C increased by the decreasing of
LiFePO4 sintering temperature and the decreasing of the dopant quantity. Carbon
coating and doping TiO2 have been successfully improving electrical conductivity
of LiFe1-xTixPO4/C. The highest conductivity of LiFe1-xTixPO4/C is obtained by
heating at 700ºC and 2% wt TiO2, i.e. in the order of 10-2S/cm.
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