Fuel cell membrane electrode sealing frame

Abstract

The invention relates to a sealing frame of a fuel cell, in particular to a membrane electrode sealing frame of the fuel cell, which is used in the fuel cell, the fuel cell comprises a CCM membrane, a membrane electrode sealing frame, carbon paper and a bipolar plate, and the sealing frame comprises a sub-sealing frame and a support frame; the two sides of the CCM membrane are respectively and sequentially provided with a sub-sealing frame, a supporting frame and a bipolar plate; the carbon paper is embedded in the membrane electrode sealing frame and covers an active area of the CCM membrane; and the total thickness of the sub-sealing frame and the supporting frame on the single side of the CCM membrane is equal to the total thickness of the compressed carbon paper on the single side of the CCM membrane. Compared with the prior art, the membrane electrode bee frame can play a role in supporting and preventing overpressure, and effectively prevents the carbon paper and the catalyst layer from being damaged due to overhigh stack pressure; and meanwhile, the precision requirement of a bipolar plate sealing glue line can be reduced, so that the electric pile is efficiently matched and assembled.

Description

technical field [0001] The invention relates to a fuel cell sealing frame, in particular to a fuel cell membrane electrode sealing frame. Background technique [0002] A proton exchange membrane fuel cell usually refers to a stack composed of membrane electrodes and bipolar plates stacked alternately, with collector plates and end plate sets at both ends, assembled in series. The inner core component of the device is the membrane electrode (MEA). MEA is composed of proton exchange membrane, catalytic layer, carbon paper and sealing frame. The carbon-supported platinum catalyst is evenly distributed on both sides of the proton exchange membrane by spraying, transfer printing and other technical means to form CCM. The diffusion layer is usually composed of carbon paper or carbon cloth, which is attached to both sides of the active area of ​​the CCM. The sealing frame is attached to the periphery of both sides of the proton exchange membrane to play a sealing role. On both s...

AI Technical Summary

Problems solved by technology

If the membrane electrode is not well sealed, two leakage situations may occur: one situation is that the fuel gas and oxidant gas are mixed inside the stack (internal leakage), and under the action of the anode or cathode catalyst, a thermochemical recombination reaction occurs rapidly, A large amount of heat is released, causing the electrolyte membrane (proton exchange membrane) to melt through, losing the function of isolating fuel gas and oxidizing gas, causing an explosion or a large area of ​​membrane electrode burning, and causing the stack to fail rapidly; another situation is fuel gas Or the oxidant gas leaks to the outside of the stack (outside leakage), which will reduce the energy utilization efficiency of the fuel cell

If the stack works in a closed or poorly ventilated space, the hydrogen concentration of the leaked fuel will continue to accumulate in the surrounding space, which will also cause an explosion, which will pose a threat to the surrounding personnel and equipment.

[0007] Even if the membrane electrode does not leak, when assembling the stack, due to the compression deformation of the carbon paper of the membrane electrode, the force on the single section of the membrane electrode in the stack will be uneven, resulting in poor performance consistency and affecting the overall performance of the stack. Power generation performance; the uneven stress on a single section of the membrane electrode may be caused by the thickness accuracy of the membrane electrode itself, the accuracy of the sealing line of the bipolar plate, and the misalignment during the assembly process

During the long-term operation of the stack, the membrane electrodes are under pressure for a long time, and in the conventional sealing structure, the sealing frame is much thinner than carbon paper, so it is difficult to ensure that hundreds of membrane electrodes are in a consistent state, resulting in Some membrane-saving electrodes have overvoltage or low performance. This wooden barrel effect has to make abnormal maintenance of the stack, which greatly increases the operation and maintenance cost.

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