Development of a compact high-power density air-cooled proton exchange membrane fuel cell stack with ultrathin steel bipolar plates

Air-cooled fuel cells used in portable stacks are required to reduce the size and weight while ensuring a high-power output. In this study, the 0.1 mm stainless steel sheet was used to form the ultrathin bipolar plates (BPs), by the reasonable flow field design and material selection, the mass of single bipolar plate is as low as 44.6 g and the thickness is only 1.9 mm with 180 cm2 active area. The 2.8 kW air-cooled stack has efficient heat dissipation, small voltage over/undershoot, rapid temperature dynamic response, and compact structure, moreover, the mass of the stack core is 3203 g and the volume of the stack is 3.36 L. The designed stack has an excellent voltage consistency, fast temperature response, and high power density. The maximum voltage overshoot is 0.035 V with a current step/drop of 10 A. The maximum temperature drop rate reaches 0.12 K s−1 in a 10% fan duty cycle step when the load current is 72 A. At 50% fan duty cycle, the temperature increase rate reaches its peak of 0.27 K s−1 when the load current steps from 70 A to 80 A. The mass power density of the designed air-cooled 56-cell stack is 0.885 kW kg−1 and the volumetric power density is 0.751 kW L−1. •Single cell thickness is 2.05 mm using ultra-thin gold coating BPs.•Mass power density of the designed stack is 0.885 kW kg−1•Volumetric power density of the designed stack is 0.751 kW L−1•The maximum temperature increase rate reaches 0.27 k s−1.