以活性炭为燃料的固体氧化物燃料电池(英文)

采用注浆成型法制备了管状电解质支撑的固体氧化物燃料电池(SOFC),电解质材料为YSZ,阳极和阴极材料都采用银.将活性炭不加任何气体直接用作电池的燃料.电池的有效面积为2.5cm2,在800℃时给出最大功率为16mW,其开路电压随温度的变化与理论结果一致.此电池在30mA的恒电流下连续稳定运行了37h,通过电化学反应消耗了加入电池中碳燃料的42%(w),证明了电池的工作是可以自维持的.与使用石墨燃料的SOFC相比,此电池的运行稳定性得到了明显的提高,因为活性炭比石墨具有大得多的微孔率和表面积.电池运行37h后很快衰减,燃料烧结和燃料量减少造成碳表面积减小可能是衰减的主要原因.电化学阻抗谱测试结果表明电池的极化电阻在电池的总损耗中占主导.通过对电池反应机理进行分析,认为发生在阳极/电解质界面的CO电化学氧化反应和发生在碳燃料表面的Boudouard反应构成的循环维持了电池的运行,因此通过添加促进上述两个反应的催化剂,可提高电池的性能.

Fueling Solid Oxide Fuel Cells with Activated Carbon

A tubular electrolyte-supporting solid oxide fuel cell (SOFC) was fabricated by a slip casting technique. Yttrium stabilized zirconia (YSZ) was used as the electrolyte and silver was used as both of the anode and cathode materials. Activated carbon was directly used to fuel the cell without any gas feeding. The cell, with an effective area of 2.5 cm2, gave a maximum power of 16 mW at 800 ℃. The relationship of the open circuit voltage vs temperature was consistent with the theoretical expectation. Operating the cell continuously and stably for 37 h at a constant current of 30 mA resulted in more than 42% (w) of the carbon fuel consumed, demonstrating that the cell was self-sustainable. Compared with the SOFCs with graphite fuel, the operation stability has been improved significantly and this is attributed to the greater microporosity and larger surface area of the activated carbon. The performance degraded rapidly after 37 h. A decrease in the active surface area of the carbon fuel, arising from carbon sintering and a reduction in the amount of fuel during the operation was assumed to be the main reason for the degradation. An electrochemical impedance measurement revealed that polarization resistance dominated the total loss of the cell. By analyzing the mechanisms of the cell reaction, we recognized that the cycle of the two reactions, i.e., the electrochemical oxidation of CO on the anode/electrolyte interface and the Boudouard reaction on the surface of the carbon fuel, maintained the cell operation. We suggest that a significant improvement in cell performance can be expected by using catalysts that promote these two reactions.