Fundamental Research on Increasing Output Power Density of Phosphoric Acid Fuel Cel

磷酸燃料电池在高功率运行时性能不稳定。本研究的目的是解释这些现象，并开发新的方法来提高输出功率密度。主要结果如下：（1）阴极催化层防潮性强时，在高功率密度运行初期会出现不稳定现象。操作前必须使磷酸渗透到催化剂层中。(2)为了加速酸的渗透，试验了真空浸渍法、超声波渗透法、加醇渗透法、电毛细渗透法和冷凝酸渗透法等5种方法。前两种利用机械外力的方法效果不佳，后三种利用毛细管力的方法效果较好，实用性强。(3)不稳定现象具有氧耗散电极面积传播的特征。通过使用贫氧气体，可以进行酸渗透的诊断试验。(4)酸浓度的周期性变化假设负载变化或启停操作影响电池性能衰减。

Unstable performance of phosphoric acid fuel cells was found at high output power operation. Purposes of this research are to explicate these phenomena and to develop new methods for increasing the output power density. Main rsults are as follows,(1) Unstable phenomena occur early in operation of high output power density when a strong wet-proofed catalyst layr of a cathode is used. It is neccessary to penetrate phosphoric acid into the catalyst layr before operation.(2) In order to accelerate the penetration of the acid, five methods are tested such as vacuum impregnation, super-sonic penetration, alcohol-added penetration, electric capillary penetration and condenced acid penetration. Former two methods using external mechanical force are not so effective, whereas the latter three methods related to capillary force are effective and practical.(3) Unstable phenomena have features of propagation of oxgen dissipated electrode area. Diagnostic tests for acid penetration are possible by using oxgen poor gas.(4) Periodic change of acid concentration assuming load change or start-stop operation affect cell performance decay.