Abstract
It is well known that previous penetration of phosphoric acid into wet proofed catalyst layer of phosphoric acid fuel cells is necessary for initial stable operation at high current density.
In order to accelerate the penetration and improve the electrode performance, five methods are tested such as ultrasonic vibration, vacuum impregnation, alcohol addition, acid concentration and electric capillarity. External pushing forces such as ultrasonic vibration or vacuum impregnation are not so effective for accelarating the penetration, whereas interfacial forces affected by alcohol addition, acid concentration or electric capillarity are much effective.
Though electrode performance increases with increasing penetrated acid volume, performance of acid penetrated electrode by alcohol addition is low compared with that by acid concentration or electric capillarity at same penetrated acid volume.
Acid penetrating mechanism, mechanism of unstable phenomena on initial operation at high current density, a diagnostic method for insufficient acid penetrated cells and accelerating methods for acid penetration into catalyst layer are proposed.
