ELECTRODE FOR SOLID ELECTROLYTE TYPE ELECTROCHEMICAL CELL

PROBLEM TO BE SOLVED: To reduce strains occurring at the time of temperature rise and temperature drop, and improve electrical conductivity by using a material from a mixture of NiAL2 O3 and NiO for a solid electrolyte, and keeping the coefficient of the thermal expansion of an electrode at a value near the coefficient of the thermal expansion of other components. SOLUTION: The coefficient of thermal expansion of a fuel electrode is kept at a value near the coefficients of thermal expansion of other components (in particular, YSZ: coefficient of thermal expansion = 10×10 /K), so as to prevent damages to a cell at the time of a temperature rise or drop. For this purpose, NiAl2 O3 and NiO are mixed, and NiO acts to maintain electron conductivity and cause the oxidizing reaction of oxygen. Thus, NiO is essential as an electrode, but the coefficient of the thermal expansion thereof is extremely high, as 14×10 /K. On the other hand, NiAl2 O3 functions as YSZ and is used for the mixture, so as to keep the same coefficient of thermal expansion as the other components. The coefficient of thermal expansion for NiAl2 O3 is 7.6×10 /K and low. Also, a crack occurs when the amount of NiAl2 O3 to be added is less than 20vol%, while conductivity drops when the amount exceeds 60vol%, due to the small amount of NiO. Thus, the amount of NiAl2 O3 to be added is kept at a value between 20vol% and 60vol%. The deterioration rate is thereby greatly reduced, and high conductivity is provided.