Changbo Lee

Cathode Properties of SmxSr1−x(Co,Fe,Ni)O3−δ/Sm0.2Ce0.8O1.9 Composite Material for Intermediate Temperature-Operating Solid Oxide Fuel Cell

Perovskite-structured cathode material containing samarium (Sm) has been recognized as a promising electrode material due to its high electrocatalytic property for intermediate temperature-operating solid oxide fuel cell (IT-SOFC). This research investigated the optimized composition of Sm x Sr 1―x (Co,Fe,Ni)O 3―δ /Sm 0.2 Ce 0.8 O 1.9 on the Sm 0.2 Ce 0.8 O 1.9 electrolyte and the possible use of an optimized composite material for the IT-SOFC system. The electrochemical and thermal properties of Sm x Sr 1―x Co,Fe,Ni)O 3―8 and its composite material with the Sm 0.2 Ce 0.8 O 1.9 electrolyte were investigated in terms of area specific resistance (ASR) and thermal expansion coefficient at various temperature conditions. Durability of the selected materials was verified by thermal cycling and long-term degradation tests. Sm 0.5 Sr 0.5 CoO 3―δ and the Sm 0.5 Sr 0.5 CoO 3―δ /Sm 0.2 Ce 0.8 O 1.9 (6:4) composite cathode showed a very low ASR of 0.87 Ωcm 2 and 0.30 Ωcm 2 at 600°C, respectively. The composite type cathode for the Sm 0.5 Sr 0.5 CoO 3―δ material was more attractive due to its thermal expansion compatibility with neighboring cell components.

Study of Optimization and Characteristics of PSCF3737(Pr 0.3 Sr 0.7 Co 0.3 Fe 0.7 O 3 ) for IT-SOFC

[ ] is a good candidate cathode material for IT-SOFC(intermediate temperature solid oxide fuel cell) because of high MIEC(mixed ionic electronic conductor) conductivity. In this study, the characteristics of PSCF3737 was investigated and optimizations of sintering temperature and thickness for was carried out. Impedance responses were divided into two parts by frequency region. Middle frequency part () was concerned with oxygen reduction reaction on surface and low frequency part () was related with oxygen diffusion. The reasonable sintering temperature and thickness of cathode were and about with regard to EIS(electrochemical impedance spectroscopy). ASR(areas specific resistance) of optimized cathode is at .

La0.8Sr0.2Co1−xMnxO3 Cathode and Its Application to Metal-Supported Solid Oxide Fuel Cells

Cathode properties of La 0.8 Sr 0.2 Co 1-x Mn x O 3 (LSCM) perovskite oxides were investigated for their application to metal-supported solid oxide fuel cells (SOFCs). La 0.8 Sr 0.2 C 0.4 Mn 0.6 O 3 (LSCM-8246) had the lowest impedance on Zr 0.85 Y 0.15 O 2 (YSZ) electrolyte among various compositions because the properties of the cathodic reaction kinetics, thermal expansion compatibility, and chemical reactivity were optimized. A Ce 0.9 Gd 0.1 O 2 (CGO) interlayer was introduced between LSCM and YSZ to inhibit the formation of resistive phases at the interface. The cathode impedance was decreased to about 113 of the noninterlayer samples. The study of the partial oxygen pressure dependence and activation energy of LSCM-8246 on CGO-layered YSZ showed that the ionization of the adsorbed oxygen is the rate-determining step of the cathode reaction at the general operation condition of SOFCs. Metal-supported single cell SOFCs with LSCM-8246 cathode were fabricated and characterized. The single cell impedance was much greater than values expected from the half cell test because the cathode in the single cell was sintered in situ during the measurement. The effect of cathode sintering was observed by measuring the current-voltage (I-V) curves and impedance spectra with time.