A porous carbon felt is being used for the electrode of a redox-flow battery. The felt is 2.5 mm thick with an apparent density of 256 kg m3; the true density of the carbon is 2170 kg m3. The felt is made up of fibers with an 18-m diameter.

1. Calculate the porosity, , and specific interfacial area, a.

2. Considering an apparent current density of 1000 Am2, if at 60 C the exchange-current density is 95 Am2, how much is the reaction kinetic polarization reduced because of the porous electrode? Assume a = c = 0.5.