Fractal micro-channel bipolar plate used in proton exchange membrane fuel cell and processing method thereof

Abstract

The invention discloses a fractal micro-channel bipolar plate used in a proton exchange membrane fuel cell and a processing method thereof. The fractal micro-channel bipolar plate comprises a cathode flow field plate (10), an anode flow field plate (11), a proton exchange membrane (8), a cathode diffusion layer (7) and an anode diffusion layer (9); an upper flow field plate (1) and a lower flow field plate (5) are equipped with fractal micro-channels each of which is provided with two branches in the next channel; bifurcation angle phi of single branch shape of the fractal micro-channel flow field structure equals pi. The fractal micro-channel structure is processed by an etching technology, and through holes on the separation membrane are processed by a laser technology. The fractal micro-channel bipolar plate used in the proton exchange membrane fuel cell can ensure that reaction gas is distributed to every part of an electrode, the fractal micro-channel structure can ensure uniform temperature distribution in the cell and small pressure drop, keep a certain linear velocity of the reaction gas in the flow field, effectively discharge the water which is generated by the electrochemical reaction, and enhance the efficiency of the fuel cell.

Description

technical field [0001] The invention relates to a fuel cell bipolar plate, in particular to a fractal microchannel bipolar plate for a proton exchange membrane fuel cell and a preparation method thereof. Background technique [0002] A fuel cell is a power generation device that can efficiently convert fuel and oxidant directly into electrical energy through electrode reactions. Proton exchange membrane fuel cell (PEMFC) is a fuel cell with perfluorosulfonic acid proton exchange membrane as electrolyte, hydrogen or methanol as fuel, and air or oxygen as oxidant. The core of the PEMFC is the membrane MEA and the bipolar plate. The membrane MEA is the place for electrochemical reactions. The bipolar plate realizes the uniform distribution of gas and the collection of current. In order to complete the two tasks of gas distribution and collection of current, the bipolar plate usually needs to have a good Excellent electrical conductivity, good thermal conductivity, resistance t...

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Problems solved by technology

The reactants cross flow in the flow field, which can improve the uniform distribution of the stack pressure load between the individual cells and the distribution of the reactants on the electrode surface. The disadvantage of the serpentine flow field is that the pressure drop is larger than that of the parallel flow field. If the flow channel is too long and the gas is gradually consumed along the flow direction, the concentration of the reaction gas will be greatly reduced, and the reaction near the outlet end will be insufficient due to the decrease in concentration, resulting in increased concentration polarization and insufficient use of the catalyst.

In order to make the proton membrane fuel cell in a high-performance working state, it is obviously very important to maintain the uniform distribution of the contact points between the membrane electrode and the bipolar plate. The inconsistency of the gas distribution in the serpentine flow field leads to the various reactions of the membrane electrode. The actual performance of the region is uneven

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