Research On Preparation And Application Of Microchannel Electrode Supported Solid Oxide Cell

Solid oxide cells（SOCs）have the ability to efficiently generate electricity from fuel without being limited by the Carnot cycle.Additionally,they can convert electricity into fuel without the use of precious metals in producing hydrogen through water electrolysis.The integration of SOCs with renewable energy sources is expected to accelerate the achievement of the goals of"carbon neutrality"and"carbon balance".At present,Ni-（Y2O3）0.08Zr0.92O2（YSZ）porous support electrodes have excellent performance in terms of conductivity,catalytic activity,and material stability.However,traditional high tortuosity porous structures have slow mass transfer,and prepared cells are prone to concentration polarization.Ni is prone to carbon deposition by directly utilizing hydrocarbon fuels.Moreover,catalyst is cannot well transport to the electrode/electrolyte effective reaction area of the porous support electrode.The undesirable result is it is difficult for the SOCs to achieve high performance and good stability when using hydrocarbon fuels.This article focuses on optimizing the pore structure of the support electrode to improve mass transfer,and achieving direct utilization of hydrocarbon fuel methane and ethanol through a coupled electrode microreactor.The specific work carried out using hydrocarbon fuels methane and ethanol to generate electricity in SOFCs and assist in electrolyzing steam in SOECs is as follows.Comparing with finger shaped pore structures and traditional porous structure support electrodes,the dendritic microchannel structure support electrode which is prepared by mesh assisted phase inversion exhibits better mass transfer effects.SOFCs not only reducing concentration polarization,but also improving the maximum power density（MPD）.The PD-Gd_0.1Ce_0.9O₂（GDC）nanocatalyst prepared by impregnation method improves the catalytic activity of the electrode for methane,which profit from the catalyst can be well distributed to the effective area of the electrode/electrolyte interface in the microchannel pore structure extends straight and continuously to the electrolyte interface.The MPD of the SOFCs is 943m W cm^-2 at 800℃which is the highest performance by impregnating the catalyst 3 times.Compared with the SOFCs without the catalyst,the SOFCs with the catalyst more stable and the cell operated stably for 114 h.A Ru-GDC fiber catalyst is loaded into the micropores which is dendritic microchannel electrode channels to prepare electrode microreactors of SOFCs for direct application of ethanol fuel.The internal reforming increased the MPD from 388.4 to 944.5 m W cm^-2 at 800℃and a low ethanol concentration of 6.5%,which is the highest-recorded MPD of oxygen ion-conducting SOFCs using ethanol fuel.The MPD increased with operation temperature and ethanol concentration while high ethanol concentration reduced ethanol conversion and potentially promoted carbon deposition.Adding steam with ethanol like conventional ethanol-fueled SOFCs greatly decreased MPD due to fuel dilution and the reduced OCV.The direct ethanol SFOCs with internal reformers demonstrated stable power generation at a current density of 1.0 A cm^-2 for 236 h at 800℃.Quasi-symmetrical SOECs with Ni-based electrodes were prepared in one step by co-sintering three layers of electrode/electrolyte/electrode,which have a dendritic microchannel electrode.Co-sintering improve the performance and stability of the SOEC at high current as the binding force of the electrode/electrolyte interface on both sides are increased.In this paper,first application of ethanol assisted electrolysis of steam in SOEC reduces OCV and the thermal energy consumption compared to traditional ethanol steam reforming for hydrogen production.Such as the electrolysis voltage of 0.36 V can achieve thermal neutral electrolysis.Most hydrogen is generated in the cathode chamber,avoiding the oxygen separation process.SOEC with coupled microreactor hence electrolysis efficiency and ethanol utilization resulting in efficient and stable steam electrolysis at a record high current density of 3.0 A cm^-2 for 209 h at 800℃.Therefore,the ethanol-assisted steam electrolysis has achieved efficient hydrogen production over the integrated SOEC reactors.Base on the SOEC coupled to micro-reactors,methane assisted steam electrolysis to produce hydrogen and synthesis gas（H₂+CO）are investigated.SOEC achieves a higher electrolytic current density of 3.96 A cm^-2 than ethanol assisted water electrolysis at an electrolytic voltage of 1.3 V at 800℃.Unfortunately,the partial oxidation of methane to assist in electrolysis of steam requires to consume heat energy.A large amount of heat is consumed at high electrolytic current density result in cell cracking due to excessive stress.A new SOC testing system has been independently designed and developed which has many advantages such as simple design,good sealing performance,and more reasonable intake design.It can flexibly regulate the atmosphere of the gas chambers while achieving gasification,quantitative control,and stable transportation of water and ethanol liquid fuels.Experiments have verified the feasibility of the SOC test system.