Fabrication And Application Of Solid Oxide Fuel Cell By Tape Casting With Electrochemical Performance And Partial Oxidation Of Methane

Solid oxide fuel cell（SOFC）,as a clean power generation device,can operate at 600～1000℃ and realize high temperature reforming of some fuels（such as CH₄）.In this paper,the technology of tape casting SOFC was studied,and the electrochemical partial oxidation of methane was realized by SOFC,in order to explore the feasibility of gas electricity cogeneration.Tape casting is a kind of ceramic molding process with simple operation and high production efficiency,which can be used to prepare flat support and flat membrane.Yttrium stabilized zirconia（YSZ）was used as electrolyte material,and the mixture of Ag and GDC was used as cathode and anode material.The green body of electrolyte film prepared by tape casting method is more uniform,so the number of lamination layers can be increased or decreased as needed,so as to control the thickness of electrolyte layer more accurately.In the experiment,12 and 8 layers of electrolyte films were stacked together and coated with electrode materials to prepare single cell.SEM showed that the thickness of 12 layers was about 224μm.The thickness of 8-layer laminated electrolyte film is about 140μm.Its electrochemical performance was tested at 800℃ with humidified hydrogen（containing 3 vol.%）.The maximum output power density is 264 mW cm^-2 for 12-layers-cell and 327 mW cm^-2 for 8-layers-cell.The results show that reducing the thickness of the electrolyte layer can improve the performance of the cell.However,in order to make the cell have enough support strength,the electrolyte thickness is limited and can’t be too thin.Therefore,only by reducing the electrolyte thickness to improve the output performance of the cell is limited.Compared with electrolyte supported SOFC,anode supported SOFC has thinner electrolyte layer,which is less than 30μm.It can effectively reduce the ohmic impedance of the cell.The anode structure with enough strength and reasonable pore distribution can greatly improve the output performance of the cell.To prepare anode slurry by tape casting method,the interaction between organic additives and powders should be considered,so as to prepare stable slurry.Zeta potential can reflect the stability of slurry system.NiO and YSZ were used as anode powders,and their mass ratio was 1:1,adding 15%of the total mass of graphite as pore forming agent.We add the dispersant TEA,binder PVB,plasticizer DOP and PEG as 8%,12%,6%and 6%of the total mass of the powder（NiO,YSZ and graphite）,respectively.At this time,the slurry has the highest zeta potential,indicating that the slurry has good stability.The Cell a was prepared with the unimproved slurry and ball milling process,and the Cell b was prepared with the improved slurry and unimproved ball milling process.Cell c was prepared by improved slurry and improved ball milling process.The maximum output power densities of Cell a,Cell b and Cell c were 455 mW cm^-2,581 mW mW cm^-2 and 887 mW cm^-2 respectively at the hydrogen flow rate of 50 ml min^-1 and 800℃.The results showed that the improved slurry and ball milling process greatly improved the output performance of the cell,reaching nearly 100%.A large electrolyte supported SOFC was prepared with an effective cathode area of 1.33cm2 and electrolyte thickness of about 210μm.Ni-YSZ was used as anode and Ag-GDC was used as cathode.At 800℃,the performance of hydrogen and methane as fuel was tested,and the maximum output power density was 156 mW cm^-2 and 131 mW cm^-2,respectively.It is found that H₂/CO changes regularly by analyzing the tail gas products of methane at different temperatures and different current densities.At the same temperature,H₂/CO decreases with the increase of power density.When the current density is the same,H₂/CO increases with increasing temperature.The proportion of syngas can be adjusted accordingly to produce corresponding chemical products.And at the current density of 700℃,135 mA cm^-2,syngas with H₂/CO ratio of 1 is obtained,which can produce carbonyl compounds in industry.The above results show that it is feasible to use SOFC to achieve methane gas and power generation.