Metal/Oxide Heterojunction Boosts Fuel Cell Cathode Reaction at Low Temperatures
Metal/Oxide Heterojunction Boosts Fuel Cell Cathode Reaction at Low Temperatures
复制标题
DOI：
10.1002/aenm.202102025
复制
发表时间：
2021-08-26
影响因子：
27.8
通讯作者：
Aoki, Yoshitaka
中科院分区：
文献类型：
--
作者：
Jeong, SeongWoo;Wang, Ning;Aoki, Yoshitaka
在几种类型的低温固体氧化物燃料电池中，氢渗透金属支撑燃料电池（HMFC）是在400摄氏度下可实现约1.0 W cm(-2)输出的装置。这项工作阐明了在如此低的温度下促进质子传导陶瓷上的阴极反应的机制。结合数值和电化学分析表明，阻断金属/氧化物异质结处的少量氧化物离子传导促进了阴极/电解质界面处的质子转移，从而提高了三相边界处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来补偿因阻挡而积累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增加，从而排出过量的质子。随着电池偏压的增加，界面质子浓度梯度增大，因此 HMFC 的阴极极化电阻减小。具有高度缺氧的 BaZr0.5Sc0.5O3-delta 电解质的 HMFC 会积累大量的氧化物离子，从而形成大的浓度梯度。因此，与传统正极材料La0.6Sr0.4Co0.2Fe0.8O3-delta相比，其在400℃下的阴极反应电阻达到0.54Ωcm(2)。这些发现表明 HMFC 可以有效地利用超电势。
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.