Research Of La_0.75Sr_0.25Cr_0.5Mn_0.5O_3-δ-based Electrode Solid Oxide Electrolysis Cell Of High Temperature Electrolysis Of CO₂

Fossil fuels extensive used had led to the increasing of CO2emissions, resulting ina series of serious environmental problems of global warming, ocean acidification, etc.CO2emissions, recycling and conversion issue had caused widespread concern aroundthe world. CO2could be electrolyzed into CO and O2by solid oxide electrolysiscell(SOEC) technic, in order to achieve CO2reduction and energy of recycling, butthere was relatively little research on CO2electrolysis with SOEC. Simultaneously, thetraditional SOEC electrochemical decomposition of CO2generally had to mix with aproportion of reducing gas (H2, CO, etc.), increasing the complexity of its use. Thispaper focused on La0.75Sr0.25Cr0.5Mn0.5O3-δ-based electrode for SOEC, without a flow ofreducing gas to achieve the electrochemical decomposition of CO2.This paper studied the electrochemical performance of LSCM, LSCM/YSZ andLSCM/SDC electrode respectively in air and CO2, in order to research the oxygenelectrode and CO2electrode of LSCM-based electrode for SOEC during the electrolysisprocess. The result showed, the electrochemical performance of symmetry cell of thesame electrode materials in air was significantly better than in CO2. The electrodecurrent density in air was much larger than the current density in CO2at the samepolarization voltage; the polarization resistance of symmetric cell in air was muchsmaller than in CO2, and the polarization resistance in air is far less than it in CO2.The polarization resistance of symmetry cells decreased rapidly with the load ofpolarization voltage increased,and this phenomenon is particularly evident in a CO2atmosphere. it indicated that under a load of a greater polarization voltage, CO2whichtook place electrochemical reaction of the cell became feasible.LSCM-based material was as the electrode for SOEC,in order to decompose CO2.The results shows LSCM、 LSCM/YSZ and LSCM/SDC SOEC all canelectrochemically decompose CO2, LSCM/SDC SOEC got the best performance,LSCM/YSZ followed, the electrolysis performance of LSCM/SDC compositeelectrode SOEC was about5to10times better than LSCM electrode SOEC. The ACimpedance spectra of the LSCM/YSZ symmetric cell showed that the polarizationresistance was respectively0.73and0.46Ω·cm2under applied2.5V and2.7Vpolarization voltages at800℃, and its resistance relative to2V (3.33Ω·cm2) werereduced by78%and86.2%. As for LSCM and LSCM/YSZ symmetry cell, temperature elevated made the electrode polarization resistance and electrolyte Ohm resistancedecrease rapidly, which significantly enhanced the performance of the electrolysis ofSOEC. But for LSCM/SDC symmetry cell,when the temperature is higher than800℃,the polarization resistance of the electrode changed slowly with the temperature, andelectrolysis efficiency of the cell no longer increased with temperature elevated.