Gas-liquid mass transfer characteristics of a novel three-dimensional flow field bipolar plate for laser additive manufacturing of proton exchange membrane fuel cell

Compared with the conventional two-dimensional flow field, the novel three-dimensional flow field can rely on the slope to force the reaction gas into the catalytic layer (CL), which effectively improves the performance of the proton exchange membrane fuel cell (PEMFC). Three novel three-dimensional flow field bipolar plates (3D-I, 3DII, 3D-III) composed of hollow slope units were designed and prepared by selective laser melting (SLM) technology in this study. The characteristics of gas-liquid mass transfer in different flow fields are compared by experiments and numerical simulations, and the effects of through-holes on the slope on the performance of PEMFC are discussed in depth. The results showed that the maximum power density generated by 3D-III was 451.4 mW/cm2, which is 21.2% and 3% higher than that of 3D-I and 3D-II, respectively. 3D-III was better than 3D-II in terms of oxygen concentration distribution, water distribution and uniformity of current density distribution. This is due to the through-holes on the main slope of 3D - III can not only facilitate the discharge of product water and reduce the water delivered to CL but also makes full use of the hollow part of the slope unit, expanding the space in which the gas can flow.