Bi 2 O 3 -based composite cathodes of solid oxide fuel cells are generally sintered at a low temperature of 750–800 °C, but the detailed information regarding the generation of electrode/electrolyte interface and its effect on the polarization performance are scarcely known. Here we assemble nanostructured 10–40 wt% Er 0.4 Bi 1.6 O 3 decorated Sm 0.95 CoO 3-δ (ESB-SmC) composite cathodes on 8 mol% yttria-stabilized zirconia electrolyte without sintering at high temperatures and the best performance is obtained on 20 wt% ESB decorated SmC, achieving a peak power density of 1.66 W cm −2 at 750 °C. We adopt a stepwise annealing approach under open circuit and polarization conditions, so as to in situ evaluate the extent of electrode/electrolyte interface generation. The results show that under open circuit conditions, the electrode/electrolyte interface of 20 wt% ESB decorated SmC electrode can be generated by annealing at 750 °C and higher, but the polarization remarkably accelerates the interface generation at lower temperatures of 600–700 °C. The present study provides new insights into the electrode/electrolyte interface generation and polarization performance of bismuth oxide based composite cathodes under the operating conditions of solid oxide fuel cells.
The reduced operating temperature is requisite for the wide application of the solid oxide fuel cells owing to the lower cost and longer lifetime. Nevertheless, in the intermediate temperature range, the significantly increased polarization loss appears in the solid oxide fuel cells, reducing the final performance. In order to solve this issue, here we report the one-dimensional CuCo2O4–Er0.4Bi1.6O3 composite fibers, which are synthesized via electrospun method and utilized as cathodes of intermediate-temperature solid oxide fuel cells. The optimal Er0.4Bi1.6O3 mass ratio of 35 wt % has been ascertained, possessing the lowest cathode polarization resistance of 0.021 Ω cm2 at 800 °C, which is 3.3 times lower than those of the CuCo2O4–Er0.4Bi1.6O3 nanoparticle-structured composite cathode. All of the results demonstrate the potential of the CuCo2O4–Er0.4Bi1.6O3 composite nanofiber serving as an efficient cathode for the intermediate temperature solid oxide fuel cells.
Zhenwei Wang,Haibin Sun,Jiao Li,Xue Guo,Qiangqiang Hu,Zanzhong Yang,Fangyong Yu,Guochang Li
Aiming to lower the activation energy and expedite the oxygen reduction reaction (ORR) process of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) cathodes for application in intermediate-temperature solid oxide fuel cells (IT-SOFCs), Er 0.4 Bi 1.6 O 3 (ESB) modified LSCF was prepared by infiltrating using organic solvents . The infiltration of ESB dramatically reduces the polarization resistances of LSCF cathodes (from 0.27 to 0.11 Ω cm 2 at 700 °C, from 0.58 to 0.25 Ω cm 2 at 650 °C), and lowers their activation energy (from 100.28 to 97.15 kJ mol −1 ). Also, ESB makes the rate-limiting step of LSCF cathodes at high frequency change from the charge transfer process on the cathode to the adsorption and diffusion of oxygen on cathode surface . The single cell with ESB infiltrated LSCF cathodes shows a peak power density of 469 mW cm −2 at 700 °C using humid hydrogen and air as fuels and oxidants, respectively, as well as a good short-term stability for 50 h.
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