IMPROVED MEMBRANE ELECTRODE UNITS

摘要

Membrane electrode unit comprises: at least one phosphoric acid containing polymer electrolyte membrane; and at least one gas diffusion electrode comprising (i) at least one catalyst layer and (ii) at least one gas diffusion medium comprising at least two gas diffusion layers, where the first and the second gas diffusion layers comprise an electrically conductive macroporous layer in which the pores exhibit an average pore diameter of 10-30 mu m and the gas diffusion medium contains polytetrafluoroethylene. Membrane electrode unit comprises: at least one phosphoric acid containing polymer electrolyte membrane; and at least one gas diffusion electrode comprising (i) at least one catalyst layer and (ii) at least one gas diffusion medium comprising at least two gas diffusion layers, where the first and the second gas diffusion layers comprise an electrically conductive macroporous layer in which the pores exhibit an average pore diameter of 10-30 mu m and the gas diffusion medium contains polytetrafluoroethylene. The first gas diffusion layer exhibits a high polytetrafluoroethylene concentration than the second gas diffusion layer. An independent claim is also included for preparing the membrane electrode unit, comprising: (a) adding polytetrafluoroethylene to a gas diffusion medium which comprises an electrically conductive macroporous layer in which the pores exhibit an average pore diameter of 10-30 mu m, (b) annealing the gas diffusion medium of (a) at a temperature of greater than 100[deg] C, and (c) adding a catalyst material to the gas diffusion medium of step (b).