A Research On The Influence Of Cathode/Electrolyte Interface Structure Evolution On Electrical Performance Of IT-SOFC

The larger internal resistance is a restrictive factor for the commercialization and functionalization of IT-SOFC(Intermediate Temperature Solid Oxide Fuel Cells).According to the previous research,the contact resistance between the electrodes and electrolyte is the decisively restrictive factor for SOFC electrical performance.In order to reduce the contact resistance,the anode and the electrolyte were co-sintered in this dissertation to minimize the contact resistance between the anode and the electrolyte.Besides,the contact resistance between the cathode and the electrolyte can be greatly diminished by introducing a denser interlayer of cathode formed by sintering of cathode powder which is ball-milled for long time.In addition,it was found that the weaken effect of contact resistance can be strengthen by co-sintering the double layer cathode(the denser layer and the looser layer).The results show that the ratio of contact resistance to the total polarization resistance can be reduced from approx.90% to approx.50% just by prolonging the ball-milling time from 0.5 h to 48 h.If the denser interlayer of cathode was introduced,the ratio of contact resistance to the total polarization resistance would be further reduced to about 20%.As a result,the electrical performance of the SOFC at 650°C can be elevated from 0.1114 W/cm~2 to 0.2841 W/cm~2.At last,the cathode was synthesized by another method,i.e.molten salts method.The optimal synthesis conditions were investigated and the phase impurity and morphology were examined by XRD and SEM.The influence of different ball-milling time on the contact conditions was compared on the basis of cathode powder synthesized by molten salts method.It was found that the contact resistance is decreased and the electrical performance was elevated after prolonging the ball-milling time.The reason is to be found that the cathode powder undergoing long-time ball-milling would produce large number of small particles which endow the powder with excellent sintering activity.As a result,a partially dense layer forms on the surface of electrolyte.Therefore the contact resistance between the cathode and electrolyte can be reduced effectively.