Characterizations of carbonized electrospun mats as diffusion layers for direct methanol fuel cells

This work attempts to evaluate the application of carbonized electrospun mats as the diffusion layers (DL) for direct methanol fuel cells (DMFC). A series of in-house fabricated polyacrylonitrile (PAN) based fibrous mats are systematically investigated in terms of physical morphology, pore size distribution, wettability, permeability, resistivity and DMFC performance. It is found that a higher PAN concentration leads to a larger fiber diameter, mean pore size, permeability and a lower through-plane areal resistance, which contribute to a higher DMFC performance due to enhancement in reactant and electron transport. To create additional pores in the fibrous mat, polylactic acid (PLA) or silicon dioxide (SiO2) are used as the pore formers and results show that the PAN/SiO2 mat is more effective on improving the DMFC performance than the PAN/PLA mat. The employment of the carbonized electrospun mats as the anode DL results in a relatively small variation in performance as compared with those as the cathode DL, suggesting the oxygen transport issue is more severe than that of methanol. The present work is anticipated to help gain understanding and guide further optimization of the carbonized electrospun mats for fuel cells and other related application fields, including flow batteries, lithium/sodium-ion batteries and supercapacitors. •Application of electrospun mats as the diffusion layers of DMFCs is evaluated.•Morphology, pore size, permeability, resistivity and DMFC performance are studied.•A higher PAN content leads to a higher permeability, conductivity and performance.•Performance variation is low for anode electrospun mats but high for cathode ones.•Though resistivity is high, PAN/SiO2 mat enhances performance by water management.