Metal foams as flow field and gas diffusion layer in direct methanol fuel cells

Metal foams are routinely used in structures to enhance stiffness and reduce weight over a range of platforms. In direct methanol fuel cells, the controlled porosity and high electrical conductivity of metal foams provide additional benefits. Performance studies were conducted with direct methanol fuel cells incorporating metal foams as the flow field. The influence of the foam pore size and density on cell performance was investigated. The performance of similar density metal foams but with different pore sizes was non-monotonic due to the opposing trends of electrical contact and CO2 removal with pore size. In contrast, for metal foams with the same in-plane pore size, the performance improved with increasing density. Because the cell operates in a diffusion-dominated regime, its performance showed a strong dependence on methanol concentration and a moderate dependence on methanol flow rate. The feasibility of using metal foams as a gas diffusion layer (GDL) was also explored.