Optimization The Properties Of LSM Oxygen Electrode For Reversible Solid Oxide Cell

Hydrogen with its advantages of high efficiency,clean and renewable could be a powerful alternative for fossil fuels.Reversible solid oxide cell（RSOC）can transform hydrogen into electricity helpful to build diversified energy supply system,or use electricity and heat to electrolyze water and CO₂ into syngas,alleviate the pressure of the greenhouse effect and energy supply.Therefore,RSOC has become a hot research direction.In this paper,oxygen electrode of RSOC was taken as the research object.On the basis of LSM oxygen electrode,infiltration and structural modification method were exerted to optimize the electrochemical performance and stability of LSM.Sm_0.5Sr_0.5O_3-δ（SSC）-Sm_0.2Ce_0.8O_1.9（SDC）was infiltrated into the LSM electrode by co-infiltration method.The influence mechanism of single infiltration SSC and co-infiltration SSC-SDC on the polarization performance of LSM was explored.At800℃,the polarization resistance of the LSM-SSC/SDC oxygen electrode was only0.07Ω·cm²,which was 3.2%of the uninfiltrated LSM oxygen electrode.The performance of Ni-YSZ/YSZ/LSM-SSC/SDC cell was under SOFC and SOEC modes were investigated.At 800°C,the maximum power density and maximum electrolysis current density of the single cell were 826 m W·cm^-2 and-1377 m A·cm^-2,respectively,which was 4.19 times and 3 times of the the single cell with LSM as the oxygen electrode.The testing results showed that the co-infiltration SSC and SDC had a significant enhancement effect on the SOFC performance and SOEC performance of the LSM oxygen electrode.SSC and SDC nanoparticles were infiltrated alternately into LSM oxygen electrode by alternating infiltration.The different mechanisms of alternately infiltrated SSC/SDC nanoparticles and single-infiltrated SSC and SDC nanoparticles on LSM properties were investigated.At 800℃,the polarization resistance of the LSM-SSC/SDC oxygen electrode was only 0.08Ω·cm²,which was 3.8%of the uninfiltrated LSM oxygen electrode.The polarization stability of the SSC/SDC-LSM oxygen electrode was explored,the result showed that the degradation rate of the SSC/SDC-LSM oxygen electrode was only 0.5‰V/h.At 800℃,the maximum power density and maximum electrolysis current density of Ni-YSZ/YSZ/SSC/SDC-LSM were 1206 m W·cm^-2 and-1620 m A·cm^-2,respectively,which was 6.1 times and 3.5times of the the single cell with LSM as the oxygen electrode,indicating that Ni-YSZ/YSZ/SSC/SDC-LSM had good reversible output performance.LSM-LSCF oxygen electrode with layered structure was designed and prepared by structural optimization method.At 800℃,the polarization resistance of the LSM-LSCF oxygen electrode was only 0.73Ω·cm²,which was 32.9%of the LSM oxygen electrode.The infiltration method was used to further optimize the electrochemical performance of LSM-LSCF electrode.The influence of infiltration of SDC solution on the microstructure and polarization impedance of LSM-LSCF was explored.SDC nanoparticles were uniformly disturbuted on the LSM-LSCF oxygen electrode,increased the electrochemical reaction active sites of LSM-LSCF oxygen electrode,improving the performance of the LSM-LSCF oxygen electrode.At 800℃,the polarization resistance of the LSM-LSCF-SDC oxygen electrode was only 0.2Ω·cm²,which was 26.7%and 9%of the LSM-LSCF oxygen electrode and LSM oxygen electrode,respectively.The prepared Ni-YSZ/YSZ/SSC/LSM-LSCF-SDC single cell showed good electrochemical performance in SOFC and SOEC mode,indicating that the LSM-LSCF-SDC oxygen electrode had excellent ORR and OER catalysis activity.