Planar array stack design aided by rapid prototyping in development of air-breathing PEMFC

Abstract

The polymer electrolyte membrane fuel cell (PEMFC) is one of the most important research topics in the new and clean energy area. The middle or high power PEMFCs can be applied to the transportation or the distributed power system. But for the small power application, it is needed to match the power requirement of the product generally. On the other hand, the direct methanol fuel cell (DMFC) is one of the most common type that researchers are interested in, but recently the miniature or the micro-PEMFCs attract more attention due to their advantages of high open circuit voltage and high power density. The objective of this study is to develop a new air-breathing planar array fuel cell stacked from 10 cells made by rapid prototyping technology which has potential for fast commercial design, low cost manufacturing, and even without converters/inverters for the system. In this paper, the main material of flow field plates is acrylonitrile–butadiene–styrene (ABS) which allows the fuel cell be mass-manufactured by plastic injection molding technology. The rapid prototyping technology is applied to construct the prototype and verify the practicability of the proposed stack design. A 10-cell air-breathing miniature PEMFC stack with a volume of 6 cm × 6 cm × 0.9 cm is developed and tested. Its segmented membrane electrode assembly (MEA) is designed with the active surface area of 1.3 cm × 1.3 cm in each individual MEA. The platinum loading at anode and cathode are 0.2 mg cm −2 and 0.4 mg cm −2, respectively. Results show that the peak power densities of the parallel connected and serial connected stack are 99 mW cm −2 at 0.425 V and 92 mW cm −2 at 4.25 V, respectively under the conditions of 70 °C relative saturated humidity ( i.e., dew point temperature), ambient temperature and free convection air. Besides, the stack performance is increased under forced convection. If the cell surface air is blown by an electric fan, the peak power densities of parallel connected and serial connected stack are improved to 123 mW cm −2 at 0.425 V and 105 mW cm −2 at 5.25 V, respectively. The forced convection air can not only increases the oxygen diffusion rate at the air-breathing surface, but also enhance the uniformity of output voltage distribution. The performance obtained in this work reaches to the state-of-the-air of air-breathing planar PEMFC stack comparing to recent literatures. In this study, the different behavior of output performance at water-rich region and water-lean region is also discussed.