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)具有燃料本身为液体、对负载波动响应快、系统重量轻等优点，有望成为汽车动力源。然而，也解决了以下问题。甲醇通过电解质膜传输并氧化，不产生电能。由于电解液的耐热性，催化反应的操作温度太低。当开发出具有高质子电导率、对甲醇的阻隔性和耐高温至200℃的聚电解质膜时，直接甲醇燃料电池系统将应用于电动汽车电源。本研究开发了一种用于DMFC的新型聚电解质膜，并对其作为电动汽车动力的新型燃料电池系统的性能进行了评价。采用等离子体接枝聚合法制备了新型填孔型固体电解质。孔洞填充电解液…更多的聚合物共价键合到基材的孔表面，基材基质在高温下保持了膜的结构，基材基质抑制了填充聚合物对进料的溶胀。溶胀抑制导致了对甲醇传输的阻隔性能。聚合物的形态和性能一直保持到它热分解的温度。将丙烯酸和乙烯基磺酸钠在耐热性能较好的多孔聚四氟乙烯基板上聚合，合成了电解液薄膜。接枝聚合物是在基质孔中形成的，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，在电解质接枝聚合物中引入磺酸盐基团必须降低电荷斥力。在单体溶液中加入盐，盐的加入有效地降低了排斥作用，可以得到磺酸盐基团密度较高的聚电解质。制得的膜具有较高的质子电导。最后，填充孔道的聚电解质在200℃左右的高温下表现出对甲醇的传输阻力。较少

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