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Metal/Oxide Heterojunction Boosts Fuel Cell Cathode Reaction at Low Temperatures

机译:金属/氧化物异质结在低温下促进燃料电池阴极反应

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Among several types of low-temperature solid oxide fuel cells, hydrogen-permeable metal-supported fuel cells (HMFCs) are devices that can achieve outputs of approximately 1.0 W cm(-2) at 400 degrees C. This work clarifies the mechanism for promoting the cathode reaction on proton-conducting ceramics at such low temperatures. Combined numerical and electrochemical analyses demonstrate that blocking minor oxide ion conduction at metal/oxide heterojunctions promotes proton transfer at the cathode/electrolyte interfaces, thereby enhancing the turnover frequency of the cathode reaction at the triple-phase boundary. The electrolyte membrane in HMFCs is forced to gain extra protons to compensate for the charge of oxide ions that accumulate because of the blocking, resulting in an increment of the proton concentration gradients near the cathode/electrolyte interfaces so as to eject the excess amount of proton. The interfacial proton concentration gradient increases and thus the cathode polarization resistance of HMFCs decrease with the cell bias. An HMFC with a highly oxygen-deficient BaZr0.5Sc0.5O3-delta electrolyte accumulates a large amount of oxide ions, thereby developing large concentration gradients. Thus, it achieves a cathode reaction resistance of 0.54 omega cm(2) at 400 degrees C with conventional cathode materials, La0.6Sr0.4Co0.2Fe0.8O3-delta. These findings demonstrate that HMFCs can efficiently utilize overpotential.
机译:在几种类型的低温固体氧化物燃料电池中,氢可渗透的金属负载燃料电池(HMFC)是在400摄氏度下可以实现约1.0W(-2)的输出的装置。这项工作阐明了促进机制在这种低温下对质子导电陶瓷的阴极反应。组合的数值和电化学分析表明,在金属/氧化物异质梗阻下阻断少量氧化离子导通促使阴极/电解质界面处的质子转移,从而提高了三相边界处的阴极反应的周转频率。 HMFC中的电解质膜被迫获得额外的质子以补偿由于阻断而累积的氧化物离子的电荷,导致阴极/电解质界面附近的质子浓度梯度的增量,以弹出过量的质子量。界面质子浓度梯度增加,因此HMFC的阴极偏振电阻随着细胞偏置而降低。具有高氧缺陷的BAZR0.5SC0.5O3-DERTA电解液的HMFC积累了大量的氧化物离子,从而显影大的浓度梯度。因此,在400摄氏度下,在400℃下,在400℃下,在常规阴极材料,LA0.6SR0.4CO0.2FE0.8O3-DELTA,实现了0.54ωcm(2)的阴极反应电阻。这些发现表明HMFC可以有效地利用过势。

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