Preparation method for three-dimensional network structure membrane electrode for direct methanol fuel cell

Abstract

The invention discloses a preparation method for a three-dimensional network structure membrane electrode for a direct methanol fuel cell, belonging to the technical field of the structure and the manufacture of the efficient membrane electrode assembly of the direct methanol fuel cell. A catalysis layer in the membrane electrode prepared by the temperature controlling ultrasound spraying processis adopted to realize the three-dimensional network structure of the catalysis layer; the amount of active sites exposed on a three-phase interface, of the catalyst, is added to provide a path for gas and liquid transmission; a carbon cloth subjected to hydrophobicity processing serves as a diffusion layer; an Nafion membrane serves as a proton exchange membrane; Pt black and PtRu black serve as catalysts, and propyl alcohol serves as a diffusion agent; a Nafion solution serves as a binder in the catalysis layer, and a PTFE (polytetrafluoroethylene) membrane or tinfoil serves as a transferring medium; the catalysis layer is transferred and pressed on two sides of the proton exchange membrane from the transferring medium; and finally, the diffusion layer is arranged on the catalysis layer by hot pressing. The formed laminar combination is the membrane electrode. The membrane electrode prepared with the method has the three-dimensional network structure and has the advantages of evenly distributed pores and centralized pore diameter, the active area of the catalysis layer is obviously enlarged, and the output power density of the cell is obviously improved.

Description

technical field [0001] The invention relates to a preparation method of a direct methanol fuel cell material, and belongs to the technical field of high-efficiency membrane electrode assembly structure and manufacture of a direct methanol fuel cell. Background technique [0002] Direct methanol fuel cell (DMFC) is a power generation device that directly converts chemical energy stored in fuel (methanol) and oxidant (oxygen or air) into electrical energy. The density is high, the fuel is directly fed when the battery is working, no reforming treatment is required, the structure is simple, the response time is short, the operation is convenient, easy to carry and store, and it is an ideal power source for portable electronic devices, mobile phones, cameras and electric vehicles. Applications considered most likely to be commercialized. [0003] Membrane electrode (MEA) is the only place for electrochemical reaction in the fuel cell, and it is the core component to ensure the ...

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Problems solved by technology

There are patents, such as CN 101626084A and CN 101276919A, etc., the above method will cause the catalyst to remain on the transfer medium in the hot pressing process, reducing the utilization rate of the catalyst. Therefore, they disclose that the catalyst slurry is directly sprayed onto the proton in a heated state. On the exchange membrane, the purpose of heating is to make the proton exchange membrane such as Nafion better stretch and flatten under negative pressure

The method of directly heating and spraying on the proton exchange membrane will cause the catalytic layer to peel off from the proton exchange membrane due to the different shrinkage rates of the catalytic layer and the proton exchange membrane when the temperature drops, and the heating and spraying process will cause MEA to lose water. When the battery is installed and operated, due to the different expansion coefficients of the catalytic layer and the proton exchange membrane, it is bound to cause peeling as the water content increases.

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