Porous Sr-doped lanthanum manganite–yttria stabilized zirconia(LSM–YSZ)oxygen electrode is prepared by an infiltration process for a reversible solid oxide fuel cell(RSOFC).X-ray diffraction and SEM analysis display that perovskite phase LSM submicro particles are evenly distributed in the porous YSZ matrix.Polarization curves and electrochemical impedance spectra are conducted for the RSOFC at 800 and 850C under both SOFC and SOEC modes.At 850℃,the single cell has the maximum power density of~726 mW/cm^(2)under SOFC mode,and electrolysis voltage of 1.35 V at 1 A/cm^(2)under SOEC mode.Fuel cell/water electrolysis cycle shows the cell has good performance stability during 6 cycles,which exhibits the LSM–YSZ oxygen electrode has high electrochemical performance and good stability.The results suggest that netw ork-like LSM–YSZ electrode made by infiltration process could be a promising oxygen electrode for high temperature RSOFCs.
The authors proposed an integrated gasification fuel cell zero-emission system.The coal char gasification is discussed using high temperature and concentration of CO_(2) produced by solid oxide fuel cells and oxy-fuel combustion.The gasification is simulated by Aspen plus based on Gibbs free energy minimization method.Gasification model of pulverized coal char is computed and analyzed.Effects of gas flow rate,pressure,preheating temperature,heat losses on syngas composition,reaction temperature,lower heating value and carbon conversion are studied.Results and parameters are determined as following.The optimum O_(2) flow rate is 20 kg/h.The reaction temperature decreases from 1645 to 1329℃when the CO_(2)flow rate increases from 0 to 5 kg/h,the CO_(2) flow rate should be operated reasonably;lower heating value reduces and reaction temperature increases as the pressure increases;compared to the CO_(2) preheating,O_(2) preheating has greater influence on reaction temperature and lower heating value.
Fluidized bed reactor is widely used in coal char-CO_2 gasification. In this work, the production of syngas by using a fluidized bed gasification technique was first investigated and then the effect of the produced syngas on the performance of the solid oxide fuel cell with a configuration of La_(0.4)Sr_(0.6) Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ)//La_(0.8)Sr_(0.2)Ga_(0.83)Mg_(0.17)O_(3-δ)//La_(0.4)Sr_(0.6) Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ)(LSCFN//LSGM//LSCFN)was studied. During the syngas production, we found that the volume fraction of CO increased with the increment of gasification temperature, and it reached a maximum value of 88.8%, corresponding to a composition of 0.76% H_2, 88.8% CO, and 10.44% CO_2, when the ratio of oxygen mass flow rate to that of coal char(MO2/Mchar) increased to 0.29. In the following utilization of the produced syngas in solid oxide fuel cells, it was found that the increasing CO volume fraction in the syngas results in a gradual increase of the peak power density of the LSCFN//LSGM//LSCFN cell. The maximum peak power density of 410 m W/cm^2 was achieved for the syngas produced at 0.29 of M_(O2)/M_(char). In the stability test, the cell voltage decreased by 4% at a constant current density of 0.475 A/cm^2 after 54 h when fueled with the syngas with the composition of 0.76% H2, 88.8% CO, and 10.44% CO_2.It reveals that a carbon deposition with the content of 13.66% in the anode is attributed to the cell performance degradation.
Hai-Bin LiNa XuYi-Hua FangHui FanZe LeiMin-Fang Han
