A Self-contained Direct Methanol Fuel Cell with Surface Tension Fuel Delivery

Direct methanol fuel cells (DMFCs) are now becoming the leading candidate of next-generation power source especially for portable electronics due to their high power density, high energy conversion efficiency and less pollution advantages. However, so far almost all DMFCs are fed with diluted methanol solution and supplied by the active pump attached in the DMFC system. This active component brings additional power consumption and extra physical space. It lowers the entire system efficiency. In this paper, a simple fuel delivery structure driven by surface tension is designed and assembled for the DMFC system. Due to the different surface tension of methanol and water, the methanol is expected to diffuse smoothly through the capillaries inside Teflon PTFE membrane into water side to form diluted fuel, whereas water is prevented from leaking to the methanol side. The experimental results demonstrated that the DMFC kit with the passive fuel delivery structure can achieve a largely extended operating time period compare to the one fed by diluted fuel. Meanwhile, the DMFC also exhibit higher fuel efficiency as power consumption is saved from active fuel delivery. Therefore, such passive fuel delivery component is believed more applicable for micro scale DMFCs developing for portable electronics.