Performance And Stability Optimisation Of Methane Fueled Solid Oxide Cells

Solid oxide electrochemical cell（SOC）is a highly promising alternative for power generation（fuel cell mode）,CO ₂ conversion and H₂ production（electrolysis mode）due to its high efficiency and low emission.It is crucial to promote the real application of the well-developed SOC technology.Yet the performance and stability of the widely used Ni/YSZ supported SOC in varied operation modes remain to be the concerns.In this work,Ni/YSZ supported SOC was produced by multi-layer co-sintering technology with infiltration of nano perovskite electrode.On the one hand,the electrodes of the cell will be optimized to enhance its stability in complex operation condition;and on the other hand,several other operation modes of the cell will be explored.First,to improve the carbon deposition resistance in CH₄ fuels,from a point view of low-cost cell preparation process,Ni/YSZ has been modified by La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ（LSCF）、La_0.8Sr_0.2Fe O_3-δ（LSF）andtap（GDC）using infiltration method.The effects of the modification on the performance and stability of Ni/YSZ has been investigated.Results suggest that the three oxides can efficiently enhance the Ni/YSZ stability.LSF and LSCF prevent the rupture of the electrode by inhibiting the carbon deposition on the Ni grains.As a contrast to LSF and LSCF,GDC can also improve Ni/YSZ performance due to its high ionic conductivity,which extends the three phase boundary of electrode.Second,the feasibility of the optimized cell in CH₄ assisted SOEC mode have also been demonstrated.Meanwhile,a current density output of-0.4 A/cm²@0.4 V-750℃has been obtained,higher than that of the symmetric cell in other studies.As compared with typical SOEC,it can reduce the electric consumption,increase the electrolysis efficiency and make full use of the by-produced O₂.Based on the above results,an energy storage concept with CO₂ reduction and syngas production by switching the cathode gas has been proposed.Experiments suggest that the cell presents well durability for 400 hours under different operation modes.It is found that the addition of GDC can enhance the redox stability of LSF in CO₂ and air atmosphere during the cycling test in different operation modes.Moreover,the thermodynamic calculations indicate the cell can realize a high energy conversion efficiency.Last,the cell structure has been further optimized by introducing of 3 mol%Y₂O₃-Zr O₂（TZP）to the anode of SOFC.The cell performance and stability has been tested.The work will provide contributions to the structure design,electrodes optimization and operation modes of a single SOC device,which will lay a foundation for the real application of the technology.