A novel approach for the quantification of inhomogeneous 3D current distribution in fuel cell electrodes
A novel approach for the quantification of inhomogeneous 3D current distribution in fuel cell electrodes
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DOI：
10.1016/j.jpowsour.2018.06.029
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发表时间：
2018-08-31
影响因子：
9.2
通讯作者：
Brandon, N. P.
中科院分区：
文献类型：
--
作者：
Bertei, A.;Yufit, V.;Brandon, N. P.
电极的微观结构特性显著影响包括固体氧化物燃料电池在内的许多电化学装置的效率和耐久性。尽管在真实的三维微观结构中模拟电化学现象是可能的，但是这种三维微观结构信息的潜力尚未被充分利用。我们在这里介绍了一个全新的方法，先进的表征不均匀的电流分布的基础上的微观结构内的每个粒子的电流的统计分析。我们量化了局部电流分布的大变化，并将其与颗粒尺寸分散相联系，表明颗粒粗化如何引发进一步的降解。我们确定了两类粒子：那些传输比平均值更多的电流，这表明10-40%更多的粒子-粒子接触，和那些产生比平均值更多的电流，其特征在于类似于2.5倍大的三相边界长度每单位体积。这两类颗粒是相互排斥的，这意味着功能层内高达30%的电极体积未被充分利用。这一基本见解远远超出了连续体建模的预测，使我们能够重新审视有关安全操作条件的现行标准，并提出基于纳米粒子渗透、模板辅助合成和增材制造的替代策略，以设计更耐用的电极。
The electrode microstructural properties significantly influence the efficiency and durability of many electrochemical devices including solid oxide fuel cells. Despite the possibility of simulating the electrochemical phenomena within real three-dimensional microstructures, the potential of such 3D microstructural information has not yet been fully exploited. We introduce here a completely new methodology for the advanced characterization of inhomogeneous current distribution based on a statistical analysis of the current of each particle within the microstructure. We quantify the large variation in local current distribution and link it to the particle size dispersion, indicating how particle coarsening can trigger further degradation. We identify two classes of particles: those transferring more current than average, which show 10-40% more particle-particle contacts, and those producing more current than average, characterized by similar to 2.5 times larger three-phase boundary length per unit volume. These two classes of particles are mutually exclusive, which implies that up to the 30% of the electrode volume within the functional layer is underutilized. This fundamental insight goes well beyond the predictions of continuum modeling, allowing us to revisit the current standards regarding safe operating conditions and to suggest alternative strategies based on nanoparticle infiltration, template-assisted synthesis and additive manufacturing for designing more durable electrodes.