Membrane electrode assembly, fuel cell monomer, fuel cell and vehicle

Abstract

The present invention relates to the field of fuel cells, and provides a membrane electrode assembly, a fuel cell monomer, a fuel cell and a vehicle. The membrane electrode assembly comprises a main body part and a flow channel layer located on the outer side of the main body part, a flow channel field is formed on the flow channel layer, and the flow channel layer is provided with a support body; and the fuel cell monomer comprises the membrane electrode assembly, the fuel cell comprises the fuel cell monomer, and the vehicle comprises the fuel cell. The membrane electrode assembly is provided with the flow channel layer, the flow channel field is formed on the flow channel layer, water formed in the membrane electrode assembly can be directly discharged through the flow channel field on the flow channel layer, and the drainage problem of the membrane electrode assembly is solved; and when the membrane electrode assembly is applied to the fuel cell, the fuel cell has the advantages of small size, good drainage performance and low cost.

Description

technical field [0001] The invention relates to the technical field of fuel cells, in particular to a membrane electrode assembly, a fuel cell unit, a fuel cell and a vehicle. Background technique [0002] A fuel cell is a high-efficiency energy conversion power generation device that uses hydrogen as the best fuel and directly converts the chemical energy in the fuel and oxidant into electrical energy by means of an electrochemical reaction without a combustion process. It does not go through the heat engine process and is not limited by the Carnot cycle, and the actual energy conversion efficiency is as high as 50% to 80%. Proton exchange membrane fuel cell is the fifth-generation fuel cell developed after alkaline fuel cell, phosphoric acid fuel cell, molten carbonate fuel cell and solid oxide fuel cell. It has low operating temperature and short start-up time. , High power density, fast load response, no electrolyte loss, etc. [0003] In automobiles and other vehicles...

AI Technical Summary

Problems solved by technology

[0003] In automobiles and other vehicles, fuel cells are used as power sources, and fuel cell stacks are used as the main power source of fuel cell vehicles. The theoretical thermodynamic single cell voltage is maintained at about 1.23 volts. The hindrance to the diffusion gas and the increase of the fuel consumption of the stack under high-power operating conditions lead to diffusion-based diffusion loss; at the same time, a large amount of water will be generated in the cathode of the proton exchange membrane fuel cell under high power, A large amount of water will be filled in the MEA diffusion layer, affecting the entry of reaction gases, making the diffusion polarization loss more obvious under high power. At the same time, due to the large operating temperature span of the fuel cell, generally between -30 ° C and 80 ° C, When the temperature in the stack is lower than the freezing point of 0°C, it will freeze, and the water that is not discharged after shutdown will freeze and adhere to the surface and inside of the catalytic layer and gas diffusion layer, obstructing the flow of gas and reducing gas permeability. It also reduces the effective activation area of ​​the catalytic layer, which affects the performance and start-up of the battery

[0004] In order to solve this problem, it mainly depends on setting up the gas diversion structure. The current gas diversion structure mainly uses the gas channel on the metal bipolar plate to transmit the gas and the cooling channel to transmit the cooling liquid. Flow channels are respectively formed on the opposite surfaces. Since the flow channels have a certain depth and the rigidity of the bipolar plate needs to be ensured, the bipolar plate needs to have sufficient thickness, which leads to a large volume of the stack formed by the final stacking. It is difficult to mount it as a power source in a vehicle

In addition, in view of the above problems, there is still a solution to the problem by using ultra-thin bipolar plates, setting shallow-depth flow channels on both sides of the bipolar plates, and then adopting a large air intake metering ratio and purging method, but the ultra-thin bipolar plates are harmful to Stiffness and strength requirements are high, and stamping and forming requirements are high, which leads to an increase in the final manufacturing cost of the battery; moreover, the shallow-depth flow channel will block the flow channel after the carbon paper is eroded and affect the gas flow; the large air intake metering ratio poses higher requirements for the BOP system. In addition, excessive purging will easily cause the proton exchange membrane to dry up, and if the purging is not thorough, the water cannot be discharged and the next startup will be affected. icing problem

Images