直接甲醇燃料电池高性能双催化层阳极的研究

Studies of high performance double catalytic layer anode for direct methanol fuel cell

提出了一种直接甲醇燃料电池(DMFC)双催化层阳极结构,该双层结构由担载型Pt-Ru/C和非担载型Pt-Ru催化层组成。测定了电池的放电性能并以扫描电镜(SEM)和能谱分析(EDX)对电池的结构进行了研究,同时,以交流阻抗法和伏安法对电极进行了表征。结果表明,在双催化层结构中,形成了催化剂浓度和孔道大小的梯度分布,改善了物料传递、质子传递、电子传递状况,提高了贵金属催化剂利用率和电池性能。在金属含量相同的条件下,同单催化层电极结构相比,双催化层电极结构的电池比功率明显提高,由135mW·m-2增加到217mW·cm-2。此外,该双催化层结构电极还能够有效地降低甲醇渗透,提高燃料利用率。

A novel double catalytic layer anode for direct methanol fuel cell (DMF C) was developed and a better performance was obtained compared with that of sin gle layer anode. A double catalytic layer anode is composed of an outer catalyst layer with 45% Pt-Ru/C and an inner catalyst layer with Pt-Ru black. The novel- structured anodes were characterized and investigated with physical and electroc hemical methods. The microstructure of the anodes were analyzed by SEM and EDX, which showed that, in the double catalytic layer anode, there existed a catalyst concentration gradient and porosity gradient, resulting in good mass transfer, proton and electron conductivity. Electrochemical impedance spectroscopy (EIS) s upplied information of smaller charge transfer resistance, whereas higher electr ochemical active area for the methanol electro-oxidation could be characterized by cyclic voltammetry (CV). With the same Pt-Ru content, the double catalytic la yer anode showed lower methanol permeation current and higher power density comp ared with that of single layer anode. The power density was increased from 135 m W·cm-2 of single layer anode to 217 mW·cm-2 of double layer anode.