A bipolar passive DMFC stack for portable applications.

A bipolar passive direct methanol fuel cell (DMFC) stack for portable applications is designed, fabricated and tested. Stainless steel sheet is chosen to fabricate the current collectors by using the traditional wire cutting and laser beam cutting techniques. A 3.5 μm Au layer is deposited on the current collectors using electroplating method to prevent electrochemical corrosion. A novel design of the current collectors is proposed, which makes internal and external electrical connections be seamlessly integrated so that the resistance loss can be reduced. The maximum power density of the passive stack is 18.7 mW cm −2 at 3 M methanol concentration. The effect of the passive DMFC stack placement mode is studied. The results indicate that the passive DMFC stack in mode B (vertical cathode air channels) exhibits better and more stable performance than its counterpart in mode A (parallel cathode air channels) in discharging of high currents. Finally, the bipolar passive DMFC stack proves its good performance in powering the experimental fan in 100 days while performance deterioration behaviour is also detected. [ABSTRACT FROM AUTHOR]