Study on Performance of Membrane Electrode Assembly for Proton Exchange Membrane Fuel Cells

Abstract: Proton exchange membrane fuel cell (PEMFC) has significant advantages such as high power density, low operating temperature and excellent stability. PEMFC has a bright future in areas such as astronavigation, submarine and electric vehicles. In order to bring the commercialization of PEMFC into reality, researchers all over the world are endeavoring to develop relative materials to decrease the cost and improve the performance of PEMFC.This paper presents the optimum preparing condition of membrane electrode assembly (MEA) with 1135 membrane. A new MEA used in proton exchange membrane fuel cell (PEMFC) was specially designed and prepared. A novel water management layer (WML) was inserted between the traditional gas diffusion layer and the catalyst layer in the MEA. Effects of the constitution and composition of WML including PTFE content and distribution, the species and loading of carbon on the performance of MEA were investigated; factors such as the application of glycerol, the sintering temperature and time which were involved in the preparation process of WML were also studied. The polarization characteristic of MEA was evaluated using the polarization plot of a single PEMFC. Experiment indicated that the optimum preparing condition of WML was Vulcan XC-72 ,350℃, 3 mg carbon/cm2 and 20% content of PTFE,and a power density as high as 0.62W/cm2 was achieved without humidification.The addition of pore former into the WML of PEMFC can improve the constitution of pores; thereby the transport resistance of reactants can be decreased. Two kinds of new pore-forming agents, NH4HCO3 which has a low decomposition temperature and a medium solubility, and (NH4)2SO4 which has a high decomposition temperature and a medium solubility, were investigated. The results showed that the electrochemical performance of MEA with suitable amount of (NH4)2SO4 additive was improved, especially for air and oxygen operations. The pore structure of WML in a MEA was investigated by the environmental scanning electron microscopy (ESEM) method, and the measurement results showed that higher porosities were obtainedThis paper also researched the effects of different platinum content in Pt/C catalyst on the performance of membrane electrode assembly (MEA).The results of XRD, CV and the polarization plots of MEA demonstrated that MEA with the catalyst of platinum content of 40% performed slightly better than that of platinum content of 20%…
Key words: PEMFC; MEA; water manage layer; pore-former

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