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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]

A “4-cell” modular passive DMFC (direct methanol fuel cell) stack, which can be freely combined and applied to various electronic devices, is designed, fabricated and tested. Two PCB (printed circuit board) based accessories are designed and fabricated for electrically connecting and mechanically assembling the “4-cell” modules. The maximum power density of the “4-cell” module is 27 mW cm −2 at 5 M methanol concentration. The steady-state performances of the modular stacks with different numbers of modules are tested. The extra power loss of the multiple module stacks due to inter-module electrical connections is predicted by mathematical fitting method. The fitting results indicate that the efficiencies of the multiple module stacks are all above 90% up to 10 modules. The dynamic performances of the modular stacks are also investigated for portable applications. The results show that the modular stacks exhibit good responsiveness and reproducibility at high loading current (>100 mA). Finally, the modular stacks are successfully applied to drive the experimental fan and charge the mobile phone. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a 6-cells direct methanol fuel cell (DMFC) stack with the volume of only 13.25 cm3 and the weight of 24.075 g is designed, fabricated and tested. First, the material characterization of the Au-coated Al current collector is investigated to exhibit superior characteristics in electric conductivity, weight and electrochemical corrosion resistance. And then the steady-state performance of the stack is tested, the maximum power output of the stack reaches 568.4 mW at room temperature. The dynamic performance and durability of the stack are also investigated in consideration of practical conditions. Results indicate that stack performance represents good responding and reproducible ability. Finally, the DMFC stack proves its good performance in powering experimental fan two times in 30 days successfully. [Copyright &y& Elsevier]