Data_Sheet_1_Cathode Optimization for an Inert-Substrate-Supported Tubular Solid Oxide Fuel Cell.doc

Inert-substrate-supported tubular solid oxide fuel cells with multi-functional layers were fabricated in this work. The tubular single cells consisted of a porous yttria-stabilized zirconia inert-substrate supporting layer, a Ni anode current collecting layer, a Ni-Ce0.8Sm0.2O1.9 anode electrochemical layer, an yttria-stabilized zirconia/Ce0.8Sm0.2O1.9 bi-layer electrolyte, and a La0.6Sr0.4Co0.2Fe0.8O3−δ cathode. Thickness of the La0.6Sr0.4Co0.2Fe0.8O3−δ cathode layer could be varied from 2.5 to 25.0 μm by controlling the number of dip-coatings in the single cell fabrication process. Electrochemical performance of the tubular single cells was investigated as a function of cathode thickness. Area specific resistance and maximum power density of the single cell were significantly affected by the thickness of the cathode. Increasing the cathode thickness to 15 μm was effective in reducing the sheet resistance of the layer and the area specific resistance of the single cell. Further increasing the cathode thickness induced a higher electrode polarization loss, which originated from insufficient gas diffusion and transport processes. Therefore, the optimum thickness of the La0.6Sr0.4Co0.2Fe0.8O3−δ cathode layer was determined to be 15 μm. At 800°C, the tubular single cell with the optimum cathode thickness displayed the highest observed maximum power density of 559 mWcm−2 under the hydrogen/air operation mode. Additionally, the tubular single cell exhibited good thermal cycling stability between 800 and 25°C for five cycles. These results illustrate the advantages of this system for future applications of the inert-substrate-supported tubular single cells in repeated startup and shut down conditions.

本研究制备了搭载多功能层的惰性载体支撑型管式固体氧化物燃料电池（solid oxide fuel cell, SOFC）。该管式单电池由多孔氧化钇稳定氧化锆（yttria-stabilized zirconia, YSZ）惰性载体支撑层、镍基阳极集流层、Ni-Ce0.8Sm0.2O1.9阳极电化学层、氧化钇稳定氧化锆/Ce0.8Sm0.2O1.9双层电解质层以及镧锶钴铁氧化物（La0.6Sr0.4Co0.2Fe0.8O3−δ, LSCF）阴极组成。通过调控单电池制备过程中的浸涂次数，可将该LSCF阴极层的厚度调控在2.5~25.0 μm范围内。本研究探究了管式单电池的电化学性能随阴极厚度的变化规律。单电池的比面积阻抗与最大功率密度均受阴极厚度的显著影响。将阴极厚度提升至15 μm时，可有效降低该层的面电阻与单电池的比面积阻抗。若继续增大阴极厚度，则会因气体扩散与传输过程不充分，引发更严重的电极极化损耗。因此，本研究确定该LSCF阴极层的最优厚度为15 μm。在800 ℃下，采用最优阴极厚度的管式单电池在氢/空气运行模式下，测得的最大功率密度可达559 mW·cm⁻²。此外，该管式单电池在800 ℃至25 ℃的温度区间内经过5次热循环后，仍表现出优异的热循环稳定性。上述研究结果表明，该惰性载体支撑管式单电池体系在反复启停工况下具备良好的应用前景。