Preparation Of Cathode Supported Solid Oxide Fuel Cells By Phase Inversion Method

With the rapid development of society,the massive fossil energy consumption has led to severe environmental problems.Finding new and cleaner energy to solve environmental and energy problems is a common challenge for all the fields of science.Solid oxide fuel cell?SOFC?is an all solid-state energy conversion device,has attracted increasing attention of people because of its high electrical conversion efficiency,low environmental impact and wide fuel flexibility.Now,there have been lots of researches on SOFCs with thin electrolyte films supported on porous anode or cathode substrates.This kind of design of SOFC could reduce the production cost of SOFCs and lower its working temperature.Compared to the anode-supported SOFCs,the cathode-supported SOFCs have received less attention because of its lower electrochemical performance.However,cathode-supported SOFCs with thinner anodes are more stable due to substantially reduced deleterious impact from the volume contraction and expansion within the anode redox cycles.Now,the main objective of cathode-supported SOFCs researchers is to improve its electrochemical performance.Except for optimizing the electrolyte or electrode materials,tailoring the microstructure of cathode substrates is also could be an effective way to enhance the performance of cathode-supported SOFCs.In this paper,we use the phase inversion tape-casting method to optimize the microstructure of cathode substrates,and then test the electrochemical performance of cathode-supported SOFCs.Chapter one gives a brief introduction of the research background,working principle and the key component of solid oxide fuel cells.And then propose the research objectives and methods of this paper.In chapter two,two kinds of La_0.8Sr_0.2MnO_3-?-Y_0.15Zr_0.85O_2-??LSM-YSZ?cathode substrates are prepared.One with finger-like straight open pores by the phase inversion tape casting,and the other with randomly distributed pores by the conventional tape casting.Though those two kinds of cathodes have similar porosity,the former one has rather better gas permeability than the latter.To obtain LSM-YSZ|YSZ|NiO-YSZ single cell,the YSZ electrolyte layer and NiO-YSZ anode layer were fabricated on the cathode substrates by dip-coating and screen printing method,respectively.The electrochemical performance of the fuel cells was measured using H₂ as fuels and air as oxidants.The cell supported on phase-inversion derived cathode showed a maximum power density of 362 mW cm-2 at 850 ?,while only 149 mW cm-2 for the cell supported on the cathode formed by the conventional method.This difference demonstrates that phase inversion tape casting method is an effective way to optimize the microstructure of cathode and improve the electrochemical performance of cell.Furthermore,the steam electrolysis performances of two cells were measured at 800 ? with different vapor pressure.Chapter three focuses on the means to lower the working temperature of cathode supported solid oxide fuel cells.La_0.6Sr_0.4FeO_3-?-Gd_0.1Ce_0.9O_1.95-??LSF-GDC?cathode substrate were prepared using phase inversion tape casting.Then also fabricate the GDC electrolyte layer and NiO-GDC anode layer on the cathode substrate by dip-coating and screen printing method,respectively.Considering the LSF and GDC both have high electric conductivity in intermediate temperature?600-800 ??,the LSF-GDC|GDC|NiO-GDC single cell is expected to have more satisfactory electrochemical performance at 600-800 ?.Chapter 5 is a brief summary of all the work in this paper and presents some suggestions for future work of cathode supported solid oxide fuel cells.