  Numerical modeling of proton exchange membrane fuel cells is at the verge of
becoming predictive. A crucial requisite for this, though, is that material
properties of the membrane-electrode assembly and their functional dependence
on the conditions of operation are known with high precision. In this bipartite
paper series we determine the most critical transport parameters for which
accurate experimental characterization is required in order to enable the
simulation of fuel cell operation with sufficient confidence from small to
large current densities. In Part II, we employ the two-phase model developed in
Part I to carry out extensive forward uncertainty propagation analyses. These
include the study of local parameter sensitivity in the vicinity of a baseline
parameter set, and a global sensitivity analysis in which a broad range of
operating conditions and material properties is covered. A comprehensive
ranking list of model parameters is presented, sorted by impact on predicted
fuel cell properties such as the current-voltage characteristics and water
balance. The top five in this list are, in this order: The membrane hydration
isotherm, the electro-osmotic drag coefficient, the membrane thickness, the
water diffusivity in the ionomer and its ionic conductivity.
