The Perparation And Performance Of The Electrode Materials For Symmetric Solid Oxide Fuel Cells

Solid Oxide Fuel Cells(SOFCs)have attracted significant attention as a clean power source that can efficiently convert chemical energy to electrical energy since the increasing serious energy and environmental crisis.The decrease of operation temperature of SOFCs to 500-800?,which can greatly reduce the fabrication and operation costs,thus is very beneficial for the application of SOFCs.As we all know,the different materials are normally selected for the anode and cathode in conventional SOFCs for their different operation conditions,Ni/YSZ cermet is the state-of hydrocarbon fuels due to the fatal problems,including carbon deposition and sulphur poisoning.Thus,the symmetrical SOFCs,for which the same material was used as both anode and cathode,have been attracted increasing attention.Moreover,the symmetrical SOFCs will reduce the fabrication and operation costs for widespread SOFCs commercialization.But there are still many problems for perovskite anode materials,including poor electrocatalytic activity,low ionic conductivity,structural instability toward redox cycling and insufficient power output.To adress these issues,systematical investigations were carried out in this work.Firstly,we designed and prepared a novel electrode material La0.6Ca0.4Fe1-xNixO3-?(x=0.2,0.4,0.6,0.8),which shows high redox stability,great electrical conductivity,excellent electrochemical performance and a high chemical compatibility with SDC.The electrical conductivity of LCFN0.2 electrode is more than 200S cm-1,which can fully meet the standard of anode.The electrode material also have excellent ORR performacne that the polarization resistance(Rp)of LCFN0.2|SDC|LCFN0.2 is 0.22?cm2.We also try to enchance the ionic conductivity and the area of triple phase boundary(TPB)by compositing SDC.The Rp of LCFN0.2-30SDC is 0.145?cm2 at 800?,which declare that composting SDC can increasing enchance the electrochemical performance of the electrode material LCFN.In a electrolyte supproted single cell,the LCFN0.2-30SDC electrode demonstrates excellent cell performance with maximum power density of 141 mW cm-2,which indicate that the designed LCFN0.2-30SDC is proven to be an attractive anode candidate for SOFCs.To further study the mechanism of in situ for anode,the additional peaks at 44.3°,51.6° and 76.1° appeared on the XRD pattern of reduced LCFN,are well matched with that of FeNi3 alloy,indicating the Ni and Fe ions has been reduced to(yFe,Ni)after H2 reduction at 800?,which can enhance the catalytic performance for H2 of anode.Meanwhile,in order to get higher performance,we designed the electrode material 30SDC-infiltrated LCFN.In a electrolyte supproted single cell,the 30SDC-infiltrated LCFN electrode demonstrates excellent cell performance with maximum power density of 302 mW cm-2 and a high stability in 140h long term testing and H2-air circling atmosphere as well.Finally,we study the structure and properties of electrode material P2NiO4(PNO)for symmatrical SOFCs,which shows high redox stability,great electrical conductivity,excellent electrochemical performance.The study of XRD,EDS and SEM reveals that PNO exsolve catalytic active metallic Ni nanoparticles on its particle surface under redox atmosphere.In a electrolyte supproted single cell,the 40SDC-infiltrated PNO electrode demonstrates excellent cell performance with maximum power density of 356 mW cm-2 and a high stability in 168h long term testing and H2-N2 circling atmosphere as well.Meanwhile,which shows that the designed 40SDC-infiltrated PNO is proven to be an attractive anode candidate for SOFCs.