Modification And Stability Of Nickel Based Anode Material For Solid Oxide Fuel Cells

Solid Oxide Fuel Cell?SOFC?as an energy device that can directly converts chemical energy into electric power,which has been attracted widespread attention due to its high efficiency,low emission and flexibility of fuels.SOFC operates directly with hydrocarbon fuels such as methane is widely expected to be an important objective for power generation in the future.However,for hydrocarbon-fueled SOFC,carbon deposition occurs mainly on conventional Ni-YSZ mental cermet anode surface,resulting in the deactivation and damage of anode,causing a notable degradation of the cell performance,as well as restrain SOFC commercial application.Therefore,this paper aims to improve the performance and ability of inhibition of carbon deposition for Ni-YSZ anode by optimizing and modifying microstructure and composition of anode when methane used as the fuel for SOFCs.?1?The modification of conventional Ni-YSZ anode was investigated from the original composition and the addition of anode pro-former,as well as the adding type of agents.The cell displayed a better performance of 271.338 m W·cm-2 under hydrogen at 800?,when the mass ratio of NiO,YSZ and starch was 6:4:0.7.On basis of this,different types of oxide such as CeO₂,Ti O₂ and Al2O3 were adopted to add in Ni-YSZ anode,and its results showed that the addition of CeO₂ could enhance the cell performance to reach 286.930 mW·cm-2.The unit cell with Ni-CeO₂-YSZ anode achieved a maximum power density of 169.819 mW·cm-2 under dry methane,which is higher of Ni-YSZ anode?139.139 mW·cm-2?.Moreover,the deactivate degree of Ni-CeO₂-YSZ anode was relative smaller on that of Ni-YSZ anode after operation 30 minutes under dry methane.?2?The reactions characteristics mechanism of low concentration?3.85% and 7.41%?dry methane on the Ni-CeO₂-YSZ anode were are investigated detailedly by measured the anode exhaust gases with on-line chromatography.For 3.85% dry methane,the addition of CeO₂ in Ni-CeO₂-YSZ anode changed the anodic catalysis selectivity to CO₂ and H2 O,or influence the generation process of CO₂ and H2 O.Also,CeO₂ can enhance the stability of transferring and storing oxygen for Ni-CeO₂-YSZ,leading to the oxidation reaction of methane and its decomposed products in anode,as well as the alleviation of carbon deposition.?3?A new type of high performance BaO/Ni_0.5Cu_0.5O_x-YSZ anode was prepared by hard template method combined with wet impregnation method.The tubular YSZ with the stereo structure was firstly prepared by hard template method to form a three dimensionally porous anode framework,and then BaO/Ni_0.5Cu_0.5O_x as catalysts was impregnated into YSZ skeleton to fabricate BaO/Ni_0.5Cu_0.5O_x composite anode material.SEM observation displayed that many tiny particles attached on tubular YSZ scaffolds,contributing to enhance anode catalytic activity and enlarge electrochemical reaction sites.YSZ electrolyte-supported unit cell with BaO/Ni_0.5Cu_0.5O_x anode was fabricated for the power generation performance test under methane and the long-term stability test with a low constant current density under dry methane at 800?.The maximum power densities were 442.730,253.860 and 322.517 mW·cm-2 at when H2,wet CH4?3%H2O?and dry CH4 were used as fuel,respectively.After 100 h operation,the voltage drop was only 2.12%,indicating that the cell performance was kept stability essentially.SEM and EDS results of tested anode confirmed that the porous anode structure was quite steady,as well as less carbon was formed in the anode,suggesting that the as-prepared BaO/Ni_0.5Cu_0.5O_x anode material had better ability for suppressing carbon deposition.