Development of Ni1-xCoxO as the cathode/interconnect contact for solid oxide fuel cells

A new type of material, Ni1-xCoxO, was developed for solid oxide fuel cell (SOFC) cathode/interconnect contact applications. The phase structure, coefficient of thermal expansion, sintering behavior, electrical properties, and mechanical bonding strength of these materials were evaluated against the requirements of the SOFC cathode/interconnect contact. A dense cathode/interconnect contact layer was developed through reaction sintering from Ni and Co metal powders. An area specific resistance (ASR) as low as 5.5 mΩ cm2 was observed after 1200 h exposure in air at 800 °C for the LSM/Ni0.33Co0.67O/AISI441 assembly. Average mechanical strengths of 6.8 and 5.0 MPa were obtained for the cathode/contact/cathode and interconnect/contact/interconnect structures, respectively. The significantly low ASR was probably due to the dense structure and therefore improved electrical conductivity of the Ni0.33Co0.67O contact and the good bonding of the interfaces between the contact and the cathode, and between the contact and the interconnect.

Research highlights
► A new type of material, Ni1-xCoxO, was investigated for solid oxide fuel cell (SOFC) cathode/interconnect contact applications.
► A dense cathode/interconnect contact layer was developed through reaction sintering from Ni and Co metal powders. An area specific resistance (ASR) as low as 5.5 mΩ.cm2 was observed after 1200 h exposure in air at 800 °C.
► Average mechanical strengths of 6.8 and 5.0 MPa were obtained for the cathode/contact/cathode and interconnect/contact/interconnect structures, respectively.