Development of direct methanol fuel cell using a novel electrolyte membrane for automobiles

直接甲醇固体聚合物燃料电池（DMFC）由于燃料本身是液体，对负载波动的响应快，系统重量轻，有望作为汽车的动力源。然而，以下问题也得到了解决。甲醇通过电解质膜运输而氧化而不产生电能。由于电解液的热耐久性，使得催化反应的操作温度过低。当一种具有高质子导电性、对甲醇的阻隔性和耐高温至200℃的聚电解质膜被开发出来后，DMFC系统将应用于电动汽车电源。本研究开发了一种新型的DMFC聚电解质膜，并对该膜作为一种新型燃料电池系统作为电动汽车的动力进行了性能评价。采用等离子体接枝聚合法制备了新型孔隙填充型固体电解质。孔隙填充电解质使更多的聚合物与衬底孔表面共价结合，衬底基质在高温下保持膜的结构，衬底基质抑制了填充聚合物对进料的膨胀。抑制膨胀导致对甲醇运输的阻隔性。聚合物的形态和性能一直保持到其热分解的温度。在耐热性高的多孔聚四氟乙烯衬底上聚合丙烯酸和乙烯基磺酸钠，合成电解质膜。接枝聚合物在基体孔隙中形成，通过改变等离子体处理和接枝条件可以控制接枝聚合物的形成轮廓。为了在电解质接枝聚合物中引入磺酸基，必须降低电荷斥力。在单体溶液中加入盐，盐有效地降低了斥力效应，加入盐可以得到具有较高磺酸基密度的聚电解质。制备的膜具有较高的质子电导率。最后，孔洞填充型聚电解质在200℃左右的高温下表现出甲醇的耐输运性。少

Direct methanol solid polymer fuel cell (DMFC).is expected as a power source for automobiles, because fuel itself is liquid and response against load fluctuation win be fast, and weight of system will be light. However, following problems have also been addressed. Methanol transport through the electrolyte membrane and oxidized without make electrical energy. The operation temperature is too low for the catalytic reaction because of electrolyte thermal durability. When a polyelectrolyte membrane which shows high proton conductance, barrier property against methanol and high temperature durability till 200℃, is developed, DMFC system will be applied for electric automobile power source. In this study, a new polyelectrolyte membrane for DMFC was developed, and the membrane performances were evaluated as a new fuel cell system as a power for electric automobile. Using plasma-graft polymerization method, the new pore filling type solid electrolyte was prepared. The pore filling electrolyte … More polymer was covalently bonded to the pore surface of the substrate, and the substrate matrix maintains the structure of the membrane under high temperature, and the substrata matrix suppress the filling polymer swelling against the feed. The swelling suppression leads to barrier property against methanol transport. The polymer morphology and properties were maintained till the temperature that it thermally decomposed. Acrylic acid and sodium vinylsulfonate were polymerized in the porous polytetrafluoroethylene substrate of which the heat-resistance is high, and an electrolyte film was synthesized. The grafted polymer was formed in the substrate pores, and the grafted polymer formation profile can be controlled by changing plasma treatment and grafting conditions.To introduce sulfonate group in the electrolyte grafted polymer, the electric charge repulsion must be decreased. Salt was added in the monomer solution, and the salt effectively decrease the repulsion effect, and polyelectrolyte with relatively high sulfonate group density can be obtained with the salt addition. Prepared membrane showed relatively high proton conductance. Finally, the pore filling polyelectrolyte showed the methanol transport resistance at high temperature around 200℃. Less