Research Of New Nafion Composite Proton Exchange Membrane Used In Fuel Cells

Proton exchange membrane fuel cell (PEMFC) has attracted extensive attention in recent years, as its high efficiency in energy conversion and zero emission. As one of key materials in direct methanol fuel cell (DMFC), proton exchange membrane can affect the overall performance and lifetime of DMFC. Currently, modification of Nafion is one of the important ways to improve the property of proton exchange membrane.In this thesis, to inhibit high methanol permeability of Nafion in DMFC, porous MnO2, Co3O4 nano-particles, sulphonated PPS (SPPS) particles or sulphonated polyether sulphone (SPES) have been prepared and added in Nafion resin solution to make composite membranes by casting method. The basic properties of the Nafion composite membranes were assasyed as well. The detailed contents are given as follows.1. Porous nano MnO2 particle was synthesized, characterized and doped in Nafion to prepare the corresponding composite membranes. The results indicate that the methanol permeability of the composite membranes could be greatly inhibited with the increase of MnO2 content. However, the proton conductivity of the composite membranes greatly dropped as well, and the ratio between proton conductivity and methanol permeability of MnO2/Nafion composite membrane is lower than that of Nafion membrane.2. Porous nano Co3O4 particle was synthesized, characterized and doped in Nafion to prepare Co3O4/Nafion composite membranes. The results show that the methanol permeability of the composite membranes could be greatly inhibited with the increase of Co3O4 content. To some extents, the proton conductivity of the composite membranes dropped as well, but the ratio between pronton conductivity and methanol permeability of Co3O4/Nafion composite membrane is similar to that of recasting Nafion membrane when the weight content of Co3O4 is 1%.3. SPPS resin has been synthesized and been doped in Nafion resin solution to prepare SPPS/Nafion composite membranes. The results show that the methanol permeability of the composite membranes could be greatly inhibited with the increase of SPPS content. The proton conductivity of SPPS/Nafion composite membranes increases with increasing sulphonation degree of SPPS. When 5wt% SPPS (sulphonation degree is 50%) doped in Nafion resin solution, the ratio between proton conductivity and methanol permeability of SPPS/Nafion composite membrane is 40% higher than that of Nafion recasting membranes.4. SPES has been synthesized and characterized as well, and doped in Nafion solution to prepare SPES/Nafion composite membranes. The results show that the methanol permeability of the composite membranes could be greatly inhibited with the increase of SPES content. The proton conductivity of SPES/Nafion composite membranes increases with increasing content of SPES. When 1wt% SPES doped in Nafion solution, the ratio between proton conductivity and methanol permeability of SPPS/Nafion composite membrane is 30% higher than that of Nafion recasting membranes.