| 摘要 |
The invention relates to a membrane electrode unit (12) and to a fuel cell (100) comprising such a unit. The membrane electrode unit (12) comprises: a polymer electrode membrane PEM (20), two catalytic electrodes (30, 31) making contact with the PEM (20) on both sides, namely an anode (30) and a cathode (31), and two gas diffusion layers (40, 41), adjoining the electrodes (30, 31) directly or indirectly, namely an anode-side gas diffusion layer (40) and a cathode-side gas diffusion layer (41), wherein at least one of the gas diffusion layers (40, 41) can optionally have a microporous layer (46, 47) facing the PEM (20). According to the invention in the layer sequence, comprising anode-side gas diffusion layer (40) / anode-side microporous layer (46) / anode (30) / PEM (20) / cathode (31) / cathode-side microporous layer (47) / cathode-side gas diffusion layer (41): a relative hydrophobicity of at least two of these components and/or a hydrophobicity variation within at least one of these components and/or a relative pore structure, comprising pore size and/or porosity, of at least two of these components and/or a variation of the pore structure within at least one of these components. Here, it is also possible for only the PEM (20) to have a hydrophobicity variation as a result of the layers (21, 22) applied to a supporting structure (23), e.g. as a result of different concentrations of ionic groups of the two polymer layers (21) and (22). The described arrangements effect an improvement in the water balance within the cell by means of structural support for the passive water transport. |
