Fabrication and electrochemical performance analysis of nanocomposite for low-temperature SOFC

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School of Science | Doctoral thesis (article-based) | Defence date: 2017-09-29
Degree programme
81 + app. 47
Aalto University publication series DOCTORAL DISSERTATIONS, 138/2017
Low-temperature solid oxide fuel cell (LTSOFC) offers a promising new energy conversion technology, which converts chemical energy into electrical energy. The benefits of LTSOFC technology include a low operating temperature, relatively high energy conversion efficiency, and potentially low costs. One of the key challenges with LTSOFC, however, is the power density and the ionic conductivity of the electrolyte, which still needs improvement. In this work, several different synthetic and fabrication processes, such as co-precipitation synthesis, freeze-drying synthesis, and spark plasma sintering (SPS) techniques were employed to enhance the performance of the composite electrolyte for the LTSOFC fuel cell. As the base electrolyte material, samarium-doped ceria (SDC) was employed, which was also modified by adding a carbonate element (CSDC). A LiNiCuZn electrode composite was utilized, which was synthesized using the slurry method. The ionic conductivity of the electrolyte could be improved via the freeze-drying and SPS methods as opposed to the co-precipitation method. The cold-pressing and hot-pressing methods were separately applied to prepare laboratory unit cells of the LTSOFC with the following results. The highest power density obtained was 1 W/cm2 at 470 oC. The best ionic conductivities were obtained by freeze-drying and the SPS, which exceeded 0.4 S/cm. In a carbonate-SDC electrolyte, adding CO2 to the air oxidant clearly improved the power density and the open circuit voltage of the fuel cell. The power density was improved by 30–100% and the OCV by 0.1–0.2 V compared to using pure air as an oxidant.
Supervising professor
Lund, Peter D., Prof., Aalto University, Department of Applied Physics, Finland
Thesis advisor
Zhu, Bin, Prof., Royal Institute of Technology KTH, Sweden and Hubei University, China
fuel cells, low-temperature SOFC, nanocomposite, ionic conductivity, hydrogen
Other note
  • [Publication 1]: Jing Y., Ma Y., Patakangas J., Zhu B., Johnsson M., Erkin C. M., Lund P. Enhanced conductivity of SDC-based nano-composite electrolyte by spark plasma sintering. International Journal of Hydrogen Energy, 39, 14391–14396 (2014).
    DOI: 10.1016/j.ijhydene.2014.02.126 View at publisher
  • [Publication 2]: Jing Y., Patakangas J., Lund P., Zhu B. An improved synthesis method of ceria-carbonate based composite electrolytes for low-temperature SOFC fuel cells. International Journal of Hydrogen Energy, 38, 16532-16538 (2013).
    DOI: 10.1016/j.ijhydene.2013.05.136 View at publisher
  • [Publication 3]: Jing Y., Qin H., Liu Q., Singh M., Zhu B., Synthesis and electrochemical performances of LiNiCuZn oxides as anode and cathode catalyst for low temperature solid oxide fuel cell. Journal of Nanoscience and Nanotechnology, 12, 1-5 (2012).
    DOI: 10.1166/jnn.2012.4940 View at publisher
  • [Publication 4]: Jing Y., Lund P. Effect of alkali carbonate in SDC electrolyte for nano-composite fuel cell. Nano Energy Systems, 1(1), 22-28 (2017).
  • [Publication 5]: Patakangas J., Jing Y., Asghar, M.I., Lund P. Investigation of LiNiCuZn-oxide electrodes prepared by different methods: synthesis, characterization and properties for nanocomposite fuel cells. International Journal of Hydrogen Energy, 41(18), 7609–7613 (2016).
    DOI: 10.1016/j.ijhydene.2015.10.133 View at publisher