Evaluation of rare earth (Yb, La) doped (Sm3Fe5O12) garnet ferrite membrane for LT-SOFC

• Rare earth element doping is a popular methodology for improving the electrical and electrochemical properties of materials. Inspired by this ideology, garnet ferrite material Sm3Fe5O12 (SFO) doped by rare earth (Yb, La) metal ions to form Sm3-0.5Yb0.5Fe5O12 (SYFO) and Sm3-0.5La0·5Fe5O12 (SLFO). The samples are synthesized by sol gel auto combustion and have been applied as electrolyte membrane for the first time in low temperature solid oxide fuel cell (LT-SOFC). The results indicate that the as-prepared materials have triple charge transport (H+/O−2/e−) carrier which promotes the hydrogen oxidation reaction (HOR) and oxygen reduction reactions (ORR) in SOFC at triple phase boundary region (TPB). Electrochemical impedance spectroscopy (EIS) reveals that the polarization resistance of SLFO membrane significantly reduces from 0.92 Ω-cm2 to 0.45 Ω-cm2 and the power output improve from 310 mW/cm2 to 650 mW/cm2 at 550 °C temperature in comparison with that of SYFO and SFO electrolyte supported cells. UV-vis diffused spectroscopy explains the semiconducting nature of the prepared materials due to the existence of optical bandgap in the semiconductor region. The further investigation also verifies the protonic conduction of SLFO membrane by constructing oxygen ion blocking fuel cell with configuration of Ni-NCAL/BZCY/SLFO/BZCY/Ni-NCAL having 427.94 mW/Cm2 fuel cell performance with 1.03 OCV at 550 °C temperature. 

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Energiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Energy Engineering (hsv//eng)

Nyckelord

Fuel cell

Garnet ferrite

Ionic transportation

Triple phase boundary

Carrier transport

Electrochemical impedance spectroscopy

Electrolytic reduction

Ferrite

Fuel cells

Garnets

Iron compounds

Lanthanum compounds

Metal ions

Metals

Oxygen

Oxygen reduction reaction

Rare earths

Samarium compounds

Semiconductor doping

Sol-gels

Solid electrolytes

Temperature

Ytterbium compounds

Electrolyte-supported cells

Fuel cell performance

Hydrogen oxidation reaction

Low temperature solid oxide fuel cells

Polarization resistances

Rare-earth element doping

Sol-gel auto-combustion

Solid oxide fuel cells (SOFC)

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