Performance of polymer electrolyte fuel cell under wet/dry conditions with hydrophilic and hydrophobic electrospun microporous layers
Xin Li, Ruiliang Liu, Ming Yao, Jianbo Zhang, Yong Liu, Yong Liu
Abstract
The electrospinning method is used to fabricate the microporous layers (MPL). The hydrophobic and hydrophilic electrospun MPLs (E-MPLs) are realized by using acetylene black and pigmented carbon black in the electrospinning ink, respectively. Scanning electron microscope shows that the E-MPLs have three-dimensional inter-connected pore structure formed by disordered nanofibers . Mercury intrusion porosimetry results indicate that the E-MPLs have larger porosity (more than 85%) and wider pore size distribution (0.8–4 μm) compared with the commercial MPL (from SGL 29BC). Hydrophobic E-MPL exhibits lower mass transport resistance at 100% relative humidity (RH) due to its larger pore size and better water drainage capability, while the hydrophilic E-MPL shows lower ohmic resistance at 40% RH due to its higher water retention capability. Fuel cell with a double-layer E-MPL, an integrated MPL containing a hydrophilic layer and a hydrophobic layer, is found to perform well under wider RH range . The fuel cell with double-layer E-MPL is found to have a better dynamic response to a current step, in that it has lower amplitude of voltage undershoot and overshoot, and reaches a steady state more quickly.