Studies On Passive-Micro Direct Methanol Fuel Cell

Fuel cells are the devices which continually convert the chemical energy of the fuel and oxidant into electrical through the electrochemical reation directly. Because of their high efficiency and environmentally safe, they have increasing attention from the governments ang enterprises all over the world. In particular, a direct methanol fuel cell(DMFC) has a lot of advantages such as high efficiency, simple configuration, no capacity degradation with reuse and recharging. Hence, they are regared as one of the most promising candidates to replace the conventional batteres for portable electronic devices. But the conventional active DMFC use the pump to supply the fuel and gas, the external devices will cause parasitic energy losses and system complexity; therefore, the elimination external devices's passive DMFC are concerned gradually.A model of anode of passive DMFC is developed, The studied domain consists of an anode current collector, an anode gas diffusion layer, an anode catalyst layer and a polymer electrolyte membrane. Than using similation the methanol distribution and gas saturation of anode porosity and open ratio, as well as the shape of inlet channel. And the result show that increasing the porosity and open ratio of anode current collector will promote transportation of methanol and CO2 removal out of cell, which result in higher work current density; and the shapes of inlet channel produce little influence on the transportation of methanol and CO2, as well as the performance of fuel cell.Using the model's parameter, membrance electrode assembly and stainless stell processed cell's plate package into a passive DMFC, with the active area is 8mm×8mm, Test and discuss the methanol concentration, cathode plate open and temperature effects the cell's performance, result show that, at room temperature, the discharge performance of cell increases at the beginning that drops with increasing the methanol concentration, and get optimal performance at 2mol/L methanol, and the cell's optimal power density is 5.6mW/cm2 ,within a certain range change the open ratio of cell ,found that the cell's performance also improve, the athode plate open ratio increasing, a reation area and oxygen change big, which help to improve cell'performance, but at the same time the internal resistance of the cell increasing, so the performance will decrease, they constraint the cell'performance. This paper received the best cathode open ratio is 50%; the performance of cell improve when increasing temperature, at a temperature of 60oC the maximum power debsity increase by nearly 60% than 20oC.