Papers by Keyword: LaGaO₃ Electrolyte

Abstract: The combination of solid oxide fuel cell technology with Fe-air battery concept was proposed by using H₂/H₂O as a redox mediator and LaGaO₃ based oxide for electrolyte. Since large internal resistance and large degradation during charge and discharge cycles are observed on anode, improvement in discharge potential and cycle stability are strongly required by improving stability of anode. In this study, cermet anode consisting of Ni-Fe alloy combined with oxide ion conductor was investigated. It was found that by using cermet anode of Ni-Fe combined with Ce_0.6Mn_0.3Fe_0.1O₂ (CMF), the observed energy density of the cell is improved to be 1109 Wh/Kg-Fe at 10 mA/cm², 873 K, which is about 92% of the theoretical energy density assuming the formation of Fe₃O₄ (1290 Wh/Kg-Fe). Cycle stability was also much improved on the cell using Ni-Fe-CMF anode comparing with that of Ni-Fe metal because of suppressed aggregation of Ni by mixing with CMF. Electrochemical charge-discharge measurement at 773 K showed excellent cycle stability over 30 cycles with high energy density (Round trip efficiency is higher than 80 %). The excellent performance and stability with operating at lower temperature promise this Fe-air solid oxide battery as the next generation energy storage device for averaging electricity and electric vehicle.

Abstract: Cermet anode of NiFe(9:1)-La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) (90:10 weight ratio) was studied for direct CH4 fueled SOFC operating at intermediate temperature. In case of NiFe bimetal anode, power density of the cell decreased drastically after operation under CH4 feeding condition. On the other hand, mixing Sm doped CeO2, MgO, or LSGM is effective for improving the long term stability. The cell with NiFe-LSGM anode exhibited much stable power density under CH4 feeding condition. Deposition of coke was also studied by Raman spectroscopy and no coke deposition was observed after 15 h operation. Since the surface activity of this anode is high, power density was hardly dependent on PCH4.It was found that NiFe-LSGM10 shows a high tolerance against the coke deposition under CH4 feeding condition.

Abstract: Effects of various additives to Ni anode on SOFC using La0.9Sr0.1Ga0.8Mg0.2O3 based oxide were investigated in this study. Among the examined additives, it was found that the addition of small amount of Fe is highly effective for increasing the anodic activity. When 5 wt% Fe was added to Ni anode, the anodic overpotential was as small as 34 mV at 873 K, 0.1A/cm2, which is almost half of pure Ni anode. Since the estimated activation energy for anodic reaction decreased, addition of Fe to Ni seems to be effective for increasing the activity of Ni for anodic reaction. XRD measurement after power generating property suggests that added Fe was formed alloy with Ni. SEM observation shows the high dispersion of Ni metal was sustained by addition of small amount of Fe. Consequently, this study reveals that Ni-Fe bimetal is highly active for anodic reaction of SOFCs at decreased temperature.