Gas diffusion layer and preparation method thereof, membrane electrode assembly and fuel cell

Abstract

The invention discloses a gas diffusion layer which is of a multi-layer microporous structure. The gas diffusion layer comprises a flow channel interface layer, a buffer layer, a fluid guide layer and an ultra-microporous layer which are sequentially stacked and arranged in the flow guide direction of reaction gas in a fuel cell, wherein the porosity of the flow channel interface layer is smaller than the porosity of the fluid guide layer and larger than the porosity of the ultra-micropores, and the buffer layer is provided with a porosity gradient with the porosity gradually increased in the first direction. According to the invention, the buffer layer with porosity gradient is arranged, so that water generated by the fuel cell during electrochemical reaction is dredged out in a relatively soft form, the problem of 'dry membrane' is effectively avoided, and meanwhile, through the combined porosity gradient arranged by the ultra-microporous layer, the fluid guide layer, the buffer layer and the flow channel interface layer, when the problem of 'dry membrane' of the fuel cell is avoided, the problem of water flooding is avoided, the water balance of the fuel cell is effectively maintained, and the performance of the fuel cell is improved.

Description

technical field [0001] The invention relates to the technical field of hydrogen fuel cells, in particular to a gas diffusion layer and a preparation method thereof, a membrane electrode assembly and a fuel cell. Background technique [0002] Fuel cell, also known as proton exchange membrane fuel cell, is currently recognized as one of the low-emission or zero-emission energy conversion devices. Its working principle is to convert the chemical energy of hydrogen and oxygen into It has the advantages of low operating temperature, fast start-up, high energy conversion efficiency, environmental friendliness, simple structure, and convenient operation. It is recognized as the preferred energy source for electric vehicles and has become the current fuel cell vehicle. mainstream power source. [0003] The core component of the fuel cell is the membrane electrode material, which is compounded and synthesized by the proton exchange membrane, catalyst layer and gas diffusion layer th...

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Problems solved by technology

[0004] However, the current design of the gas diffusion layer is relatively simple. For example, the invention patent with the application number 201010524791.X discloses a gas diffusion layer with a gradient pore structure and its preparation and application. The gas diffusion layer is made of macroporous carbon The support body and the microporous layer are superimposed, and the constituent materials of the microporous layer are inlaid into the carbon-based support body from the side of the macroporous carbon-based support far away from the battery flow field to form a transitional pore layer. The gas diffusion layer The curvature of the reaction gas transfer from the side adjacent to the flow field to the side adjacent to the catalytic layer shows a gradient increase trend. This simplified structure effectively increases the water and gas in the gas diffusion layer. The mass transfer curvature is beneficial to maintain the liquid water inside the battery, but it cannot guarantee the water balance in the fuel cell, which can easily cause the "flooding" of the fuel cell and reduce the performance of the fuel cell

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