Research Of Solid Oxygen Electrolysis Cell With Spinel MnCo₂O₄ Electrode

Solid oxide electrolysis cell?SOEC?is an advanced electrochemical energy conversion device with high conversion efficiency and energy efficiency.With intermittent renewable clean energy as electric energy and industrial waste heat as heat energy,SOEC can convert H₂O or CO₂ into H₂ or CO.It contributes to CO₂ conversion and utilization and eliminates greenhouse effects.Furthermore,the effective energy storage device is beneficial to development of new energy technologies.In addition,combination with conversion devices like solid oxide fuel cells?SOFC?makes it possible to utilize energy more effective,which can alleviate the energy crisis during the transitional period.As for H₂O or CO₂ electrolysis,high temperature operation is the better choice for cost and efficiency.Therefore,solid oxide cells are commonly operated at medium temperature and high temperature?600¹000°C?.Being regarded as the reverse process of SOFC,the traditional SOEC is used to have many similar requirements in device structure with SOFC.Apart from perovskite oxide materials,spinel oxides with considerable electrical conductivity,remarkable oxidation resistance,suitable structural stability and high reaction activityre also regard as hopeful materials for electrodes.The poor stability at high temperature of most spinel materials limits their development as electrodes in SOEC.In this paper,MnCo₂O₄ spinel material is researched as symmetrical electrodes in SSOEC and oxygen electrode in RSOC for its high temperature stability,good OER and ORR activity.The main research conclusions of this paper are as follows:?1?MnCo₂O₄-GDC composite electrodes was prepared on YSZ electrolyte by impregnation method,and the electrochemical performance of pure CO₂ electrolysis were measured with the structure of MnCo₂O₄-GDC|YSZ|GDC-MnCo₂O₄.Polarization resistance is 1.43?cm² under OCV at 800°C,and current density can reach 750 mA cm^-2 with applied voltage of 1.5 V.The cell also shows very stable performance a constant current density of 200 mA cm^-2 for 84 h,of which degradation rate is about7.23×10^-4 Vh^-1.In the paper,the cell shows high electrochemical performance and good long-term stability.?2?MnCo₂O₄-GDC composite electrode was researched as the oxygen electrode of RSOC.Electrochemical performance and stability are measured both in SOFC and SOEC modes.In SOFC mode,power density can reach 906 mW cm^-2 at 800°C,and polarization resistance is 0.293?cm².In SOEC mode,polarization resistance is 0.262?cm² under OCV at 800°C,and current density can reach 712 mA cm^-2 with applied voltage of 1.5 V.RSOC with MnCo₂O₄-GDC composite oxygen electrode shows high power density in SOFC mode and good performance in SOEC mode.It indicates that the composite oxygen electrode is of good reversibility and stability.