Nickel Based Anode Material And Single Layer Solid Oxide Fuel Cell

The effective ways to promote the development of solid oxide fuel cell(SOFC)include lowering operation temperature and using hydrocarbon as fuel.The development of anode materials that possess high catalytic activity in the intermediate temperature range and keep high stability with hydrocarbon fuels is critical.Ni-based cermet is quite a competitive anode material with high electronic conductivity,excellent catalytic activity,and low price.However,Ni-based anode is prone to coking when the hydrocarbon is supplied as fuel.Besides,when the anode sintering temperature is low,the anode conductivity is low.Aiming to these defects,Ni-based anode is prepared through a new synthesis method to improve its electrical conductivity and is modified to enhance its coking resistance.Nano-sized NiO-Ce_0.8Sm_0.2O_1.9(SDC)anode material with excellent sintering ability is synthesized through a one-step hydrothermal method.The average size of the particles in the anode material is about 10 nm.Different phases distribute uniformly in the composite.The anode calcined at 700? exhibits an electrical conductivity of above100 S cm^-1,three orders of magnitude higher than that of a similar solid-mixed composite anode with the same composition.An SDC-carbonate composite electrolyte-supported single cell with the composite anode exhibits a maximum power density of738 m W cm^-2 at 700? with H₂ as fuel,much higher than that of a similar cell with a solid-mixed anode.The cell also exhibits promising stability with methanol as fuel.In order to increase the anode coking resistance,Nb Ox is introduced into Ni-SDC anode by the incipient wetness impregnation method.Nb Ox-Ni-SDC material is applied as anode material in SOFC fueled with methanol.Nb(IV)and Nb(V)coexist in the reduced anode material.At 700?,the cell with 5Nb Ox-Ni-SDC as anode and SDC-carbonate as electrolyte achieves a maximum power density of 687 m W cm^-2.The addition of Nb increases the electronic cloud density of Ni,indicationg the existence of Nb-Ni interaction,which facilites the anode material captures and adsorbs more methanol molecules.It promotes the oxidation of methanol molecules,improving the electrochemical performance.The output voltage of the cell with 5Nb Ox-Ni-SDC material as anode only drops 4.5%during 8 h discharge.It is found that the water produced on the anode side in the electrochemical reaction is adsorbed by the Nb species and forms hydroxide,which oxidizes the carbon deposited on the Ni surface.The oxided carbon expelles from the anode side in the form of carbon dioxide.The improved stability of the single cell is achieved.The Fe-Ni alloy composite anode material Ni-La_0.8Sr_0.2Fe O₃(LSF)is synthesized with the strategy of transition metal exsolution in perovskite B-site.The anode material is applied to intermediate temperature SOFC with syngas as fuel.In reduction atmosphere,the increase of Ni content promotes the exsolution of Fe and increases the reaction site of Fe-Ni bimetallic alloy.The maximum power density of the cell with10Ni-LSF as the anode is 550 m W cm^-2 fueled with syngas at 700?.The formed Fe-Ni bimetallic alloy optimizes the local electronic structure of the active sites,and the generation of more oxygen vacancies in the oxide substrate,which synergistically improves the electrochemical performance of the cell.The cell performance does not decrease significantly during the 10 h discharge.It is found that the Fe-Ni alloy embedded in the oxide substrate helps to inhibit the sintering of alloy particles and the formation of carbon deposits,which improves the stability of the cell.Besides,in order to simplify the configuration of intermediate temperature SOFC,single layer fuel cell(SLFC)is developed.In this work,the Li_0.15Ni_0.45Zn_0.4O(LNZ)-Gd_0.1Ce_0.9O_1.9(GDC)-(Na_0.43Li_0.32K_0.25)₂CO₃(NLKC)nanocomposite is constructed,which couples the conductive properties of the semiconductor material LNZ and the ionic conductor material GDC-NLKC.The conductivity of the composite material achieves balance by optimizing the electronic conductivity and ionic conductivity,significantly improving the performance of the SLFC.The maximum power density of the SLFC composed of LNZ-GDC-NLKC material at 600°C is 582 m W cm^-2.Compared with the cell composed of the GDC-NLKC material,the cell composed of the LNZ-GDC-NLKC composite material possesses better electronic conduction and lower electrode polarization resistance,resulting in the SLFC achieving excellent cell performance.