Study On The Oxygen Reduction Reaction And The Anti-CO₂ Toxicity Of Perovskite Cathode

Solid oxide fuel cell(SOFC)is an energy conversion device with safety,high energy conversion and environmentally friendly.However,the commercial SOFC operating temperature is relatively high(800?1000 OC),excessive high operating temperature will seriously affect the performance of the material,thereby reducing the battery life and limiting the promotion and application of SOFC.Therefore,researchers are committed to reducing the operating temperature of SOFC.However,reducing the operating temperature will lead to the degradation of oxygen reduction reaction(ORR)activity of cathode,and the toxicity of CO2 will also cause the degradation.Therefore,based on the above two considerations,this paper systematically studies the catalytic activity of the cathode and the anti-CO2 toxicity of the cathode.1.The introduction of Sr2+ deficiency in perovskite oxides can alter the crystal structure,oxygen stoichiometry and other physiochemical properties.It was found that the Sr0.95Co0.8Nb0.1Ta0.1O3-?(S095CNT)perovskite oxides displayed a higher oxygen vacancy concentration than that of SrCo0.8Nb0.1Ta0.1O3-?(S100CNT).The decreased average bonding energy(ABE)and the increased critical radius(rc)of S095CNT could be responsible for the decreased activation energy for oxygen ions transfer.Consequently,the S095CNT cathode shows an area specific resistance of 0.07 ? cm2 at 650?,which was only about 63%of S100CNT.The electrolyte supported single cell by S095CNT as cathode had maximum power density of 332 mWcm-2.In addition,no obvious deterioration has been found in the stability test for 100 h,showing good chemical stability.2.The CO2 tolerance of S100CNT,S095CNT and Ba0.5Sr0.5Co0.8Fe0.2O3-?(BSCF)cathode materials was characterized and evaluated.Moreover,the S100CNT and S095CNT displayed excellen crystal stability and better CO2 tolarence than that of BSCF because of doping relatively high valence and high acidity Nb5+ and Ta5+ ions and less alkaline earth metal element.Compared with the S100CN cathode,S095CNT with a lower the average metal-oxygen bond energy(<-ABE>)and more surface adsorption sites,which is easier to adsorb CO2 molecules and to generate carbonate,showing a higher performance degradation.Therefore,the polarization impedance of S095CNT,S100CNT and BSCF increased 3.04,2.43 and 8.96 times respectively in the atmosphere of 10%CO2 at 600?.Therefore,the anti-CO2 properties of the three samples are as follows:S100CNT>S095CNT>BSCF.3.The electrochemical catalytic activity of S100CNT was improved by impregnating La2NiO4(LNO)with a chemical solution.With the increase of LNO impregnation to 10 wt%,the oxygen adsorption and transport properties of cathode materials increase,and the polarization impedance of cathode decreases The SIOOCNT-IOLNO composite cathode exhibited the best ORR activity.The polarization impedance of the SIOOCNT-IOLNO composite cathode was 0.582,0.285,0.12 and 0.106 ? cm2 at 500-650?,respectively.In addition,the polarization impedance degenerate rate of SIOOCNT-IOLNO cathode is 5.95×10-4 cm2/mi at 500?,which is one order of magnitude lower than that of S100CNT cathode under the same conditions.Therefore,the S100CNT-LNO composite cathode prepared by chemical solution impregnation shows better ORR activity and good anti-CO2 poisoning.