Abstract:
Fuel cells are devices that convert the chemical energy of the fuel directly in to electrical
energy and heat by electrochemical reactions. Interest in fuel cells started growing steadily
with the question of how to provide electrical energy to support the growing energy economy
in the world without the risk of pollution. Today’s fuel cells have provided answer to all the
question and have an immiscible potential to supply partially supply world energy needs in
the future in case of oil crises. Among the different types of fuel cells, solid oxide fuel cell
(SOFC) with perovskite structure are mostly applied and studied. LaMnO
3
is recently one of
the most intensively studied cathode materials for SOFC. In the present study, LaMnO3-
,
La0.8
Sr0.1Co0.1MnO3-
and La
0.8
Sr 0.1
Fe0.1MnO3- cathode materials were synthesized by
combustion method. The effect of substitution of Sr and Co/Fe cations for La cations on
thermal, structure, electrical and electrochemical properties of the so lid e lectrolytes were
investigate. TGA/DTA analysis confirms that the calcination temperature (1000
O
C) used is
the appropriate temperature for the preparation of all these materials using La (NO3
)
3.6H
2
O,
MnSO4.H
2
O, Co(NO3
)
2.6H
2O, Fe(NO3
)
3.9H
2O and C6H8O7
.H2
O precursors. The XRD
results of all materials reveal the formation of the hexagonal structure with R-3C space group
Fd- 3m. SEM characterization shows that the prepared samples have slightly porous structure
with agglomerated particles. The EDS analysis also confirms the presence of La, Mn, Sr, Co,
Fe and O elements in all synthesized materials. From the FTIR analysis, t he most significant
absorption bands located at 1629.8cm
-1
and 589.9cm
-1
wave numbers are identified. The
room temperature conductivity o f all samples is found to be 6.3 × 10
-3
, 8.7 × 10
- 3
and 5.8 ×
10
-3
S.cm
-1
for LaMnO
3
, La
0.8
Sr0.1Co0.1MnO3-
and La
0.8
Sr 0.1
Fe0.1MnO3-
of cathode
materials, respectively. From the diel ectric constant ε′ as a function of frequency study, it is
observed that value of ε′ maximum at lower frequencies and it begins to drop and becomes
constant at higher frequencies.
