Study On Performance Of Solid Oxide Fuel Cell With Hollow And Symmetric Structure For Ammonia As Fuel

Solid oxide fuel cells are widely concerned because of its advantages such as high efficiency,clean and wide fuel alternatives.The traditional SOFCs with ultrathin anodesupported planar structure is common application in commercialization,which have great output electronic properties.However,this type SOFCs are easy to warp because of the mismatch of thermal expansion coefficient between its components,causing low tolerance of redox and short lifetime.The output performance of SOFCs with hollow and symmetrical structure based on the traditional SOFCs was researched,and the durability and applicability of ammonia were also studied.(1)The microstructure and electrical performance of SOFCs with hollow and symmetrical structure prepared by dry press molding and extrusion molding methods were characterized.The results showed that the anodes prepared by extrusion molding had a better pore network structure and higher porosity than that of press molding,which was consistent with the performance.Long-term constant current discharge test and thermal cycle performance were also studied.The results showed that the voltage decayed rapidly after a certain period of operation.The decay rates of the two cells prepared by dry press molding were 12.3% and 12.7%.The SEM results showed that the microstructure of the cell were intact,and there was no peeling or destruction on the interface between each functional layer.The thermal cycle research showed that the open circuit voltage of the cell was stable under the working condition,and the output performance had a certain decay,indicating that the cell has a package and its own airtight stability,while the influence of thermal cycling on performance was still obvious.(2)The redox tolerance characteristic of SOFCs with hollow and symmetrical structure was investigated.The results showed electrical performance of the cell began to decline when it was oxidized for 20 minutes under the discharge current of 1A(that is,when the oxidation depth was 0.44%);After continuously oxidized for 45 minutes in open circuit,electrical performance of the cell began to decline.In additional,Ni growth phenomenon was found in the pores of the supported anode near the side of the active anode prepared by extrusion molding method.The growth of Ni was independent on the number of oxidation cycles but the depth of oxidation.(3)The applicability of ammonia fuel for extrusion molding cells with better performance was studied.The results showed that the ammonia fuel cell had electrical performance similar to those of the hydrogen fuel cell,and the performance was improved as ammonia flow rate and temperature increasing.In addition,conversion rate in the ammonia were compared when SOFCs used internal reforming,external reforming,and direct ammonia fuel gas.The results showed that the external reforming conversion rate reached 100% at the working temperature,while the internal reforming conversion rate was 94%,and the direct ammonia conversion rate was 70%.