Direct electrolysis of CO2 using an oxygen-ion conducting solid oxide electrolyzer based on La0.75Sr0.25Cr0.5Mn0.5O3 − δ electrode
Direct electrolysis of CO2 using an oxygen-ion conducting solid oxide electrolyzer based on La0.75Sr0.25Cr0.5Mn0.5O3 − δ electrode
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DOI：
10.1016/j.jpowsour.2012.12.068
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发表时间：
2013-05
影响因子：
9.2
通讯作者：
Shanshan Xu;Shisong Li;Weitang Yao;D. Dong;Kui Xie
中科院分区：
文献类型：
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作者：
Shanshan Xu;Shisong Li;Weitang Yao;D. Dong;Kui Xie
基于氧化还原可逆La0.75Sr0.25Cr0.5Mn0.5O3和−-δ(LSCM)的复合燃料电极可以在没有还原气体的情况下工作。采用LSCM-SDC/YSZ/LSCM-SDC结构的对称固体氧化物电解槽，在800℃下对CO2进行了高效电解。研究了LSCM-SDC/YSZ/LSCM-SDC在空气中的电导率与温度和氧分压的关系，并与对称槽中的电极极化进行了关联。在800℃(0.325Ω/cm2)的空气中，液晶硅电极表现出较低的电极极化，当通过电流激活液晶硅电极时，电极极化可以进一步降低到0.25xΩ/cm2。而CO2中对称电池的电极极化在开路循环和小电流条件下达到5-10Ω/cm2。然而，在大电流(例如100-200mA/cmΩ−2)下，电极活化的电流降至0.5x/cm2。交流阻抗谱和I-V测试结果表明，LSCM燃料电极在低电压下的电化学还原和高电压下CO2的电解是两个主要过程。在800℃下，1.0、1.5和2.0伏的电流效率分别达到69%、58%和56%。
Composite fuel electrode based on redox-reversible La0.75Sr0.25Cr0.5Mn0.5O3 − δ(LSCM) can be operated without a flow of reducing gas. We demonstrate the efficient electrolysis of CO2using a symmetric solid oxide electrolyzer with a configuration of LSCM–SDC/YSZ/LSCM–SDC at 800 °C. The temperature dependence of LSCM conductivity in air and the oxygen partial pressure dependence are investigated and correlated to electrode polarization in the symmetric cell. The LSCM electrode exhibits low electrode polarization in air at 800 °C (0.325 Ω cm2), and the electrode polarization can be further reduced to 0.25 Ω cm2when passing current to activate LSCM electrodes. In contrast, the electrode polarization of the symmetric cell in CO2reached 5–10 Ω cm2under OCV and low current. However, it is decreased to 0.5 Ω cm2at large currents (e.g. 100–200 mA cm−2) for electrode activation. The results of AC impedance spectroscopy and I–V tests indicate two main processes: the electrochemical reduction of LSCM fuel electrode at low voltages and the electrolysis of CO2at high voltages. The current efficiency reaches 69%, 58% and 56% at 1.0, 1.5 and 2.0 V for the electrolysis of CO2at 800 °C, respectively.