Manufacture of a non-stoichiometric LSM cathode SOFC material by aqueous tape casting

This work deals with the manufacture of non-stoichiometric strontium-doped lanthanum manganite (LSM) as a cathode material by aqueous colloidal processing. This requires some knowledge of the processability and sinterability of this material. The stability of aqueous suspensions of a fine non-stoichiometric LSM powder was studied by measuring the zeta potential as a function of pH and deflocculant content. Concentrated suspensions were prepared to solids loadings as high as 50 vol.%. The best dispersing conditions and the influence of binders and tape casting performance were determined by means of rheological measurements. LSM cathode tapes were characterized in the green state and after sintering at 1500 °C/2 h, leading to high density compacts. Maximum sintering rate is achieved at 1350 °C. Once the sintering behavior is known a porous material can be easily designed using a sintering temperature compatible with the other components of the semi-cell.