CN107887612B - Processing method of graphite bipolar plate of fuel cell - Google Patents

Abstract

The invention discloses a novel processing method of a graphite bipolar plate of a fuel cell. The main raw materials comprise petroleum coke, coal tar pitch and mesocarbon microbeads, and the fuel cell bipolar plate is prepared by sequentially carrying out the process steps of pressing, roasting, dipping, secondary roasting, graphitization, machining and the like. The graphite bipolar plate of the fuel cell solves the problems of low mechanical strength, high machining difficulty, poor air tightness and the like of the bipolar plate made of a pure graphite plate because the coal pitch and the mesocarbon microbeads are used for impregnation processing, and the problems of influenced conductivity and corrosion resistance and the like of the bipolar plate made of the pure graphite plate can be solved because no resin binder is used.

Description

Processing method of graphite bipolar plate of fuel cell

Technical Field

The invention relates to a processing method of a graphite plate, in particular to a processing method of a graphite bipolar plate of a fuel cell.

Background

A fuel Cell (PEMFC) is a power generation device that directly converts chemical energy in a fuel and an oxidant into electrical energy through an electrocatalytic reaction at an electrode. The fuel cell bipolar plate is an important component in a fuel cell stack, the power generation performance of the fuel cell is directly influenced by the quality of the bipolar plate, and the bipolar plate accounts for higher cost which generally accounts for 60-70% of the cost of the fuel cell.

The ideal bipolar plate should be a good conductor of electricity and heat, and has the characteristics of good mechanical property, good gas barrier property, lower density, good corrosion resistance and the like. In a conventional PEMFC, the flow field and the electrode plate may be integrated or separated. The research and application of the current bipolar plates mainly focus on metal material plates, molded material plates and graphite material plates, and the three bipolar plates have the advantages that: 1. the metal material bipolar plate has high mechanical strength, good conductivity and good impermeability, and has the weak point of poor corrosion resistance; 2. the molding material bipolar plate has large one-time investment in the early stage and needs to be selected between the conductivity and the strength; 3. the graphite bipolar plate has good conductivity and corrosion resistance, and has the defects of low strength and pores, so that the strength of the graphite material needs to be improved, and the inherent irregular pores of the graphite material need to be filled, so that the use requirement of a fuel cell stack is met.

The traditional graphite plate machining is still the most common scheme in the current fuel cell bipolar plate, and the graphite material has the characteristics of porosity, air permeability, brittleness and the like, so that the graphite bipolar plate is adopted

Proton exchange membrane fuel cell stacks are very costly and have relatively low reliability. In the occasions with low volume and weight requirements on the fuel cell, the traditional graphite plate machining method still plays an important role.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a novel method for processing a graphite bipolar plate of a fuel cell.

The invention adopts impregnant to carry out vacuum pressure impregnation on the fuel cell bipolar plate obtained by pressing, molding and roasting petroleum coke powder, then carries out secondary roasting treatment on the impregnated fuel cell bipolar plate, carries out graphitization treatment on the product after the secondary roasting, and then carries out machining on the fuel cell graphite bipolar plate.

The impregnant is a mixture of coal pitch and mesocarbon microbeads, and the mixing ratio is coal pitch: the mesocarbon microbeads =10:1 to 100: 1.

The vacuum pressurization dipping processing comprises the steps of heating the bipolar plate, putting the bipolar plate into a dipping tank, vacuumizing to-0.07 MPa to-0.1 MPa, adding the impregnant to completely submerge the bipolar plate, and pressurizing the dipping tank for 1-24 hours.

The granularity of the mesocarbon microbeads is 0.5-30 mu m.

The heating of the bipolar plate is to heat the bipolar plate to 200-400 ℃.

The pressure for pressurizing the impregnation tank is 1MPa to 20 MPa.

The invention has the following beneficial effects:

the processing of the graphite bipolar plate of the fuel cell adopts the novel impregnant and the special impregnation method, so that the graphite bipolar plate of the fuel cell has excellent conductivity and corrosion resistance, higher mechanical strength and good gas tightness, and can completely meet the use requirements of the fuel cell.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

Detailed Description

The following further illustrates embodiments of the invention with reference to specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Examples

Petroleum coke powder with different granularities is used as a raw material, graded according to different proportions according to a formula, and after fully stirring and kneading, the raw material is placed in a forming machine for forming.

And secondly, after the formed product is fully cooled, roasting the product according to a preset temperature rise curve.

Preparing needed impregnant, wherein the impregnant comprises coal pitch: the mesocarbon microbeads =50:1, and the particle size range of the mesocarbon microbeads is 1-5 μm.

Fourthly, heating the roasted product, wherein the final heating temperature is 320 ℃.

Fifthly, putting the heated product into an impregnation tank, vacuumizing the impregnation tank, keeping the vacuum degree at-0.08 MPa for 30 minutes.

Sixthly, injecting the prepared impregnant into an impregnation tank to completely submerge products to be impregnated.

Seventhly, pressurizing the impregnation tank, wherein the pressurizing pressure is 5MPa, and the impregnation time under the pressurizing is 4 hours.

And eighthly, roasting the soaked product according to a preset temperature rise curve.

Ninthly, graphitizing the product after roasting.

And (c) performing corresponding machining on the graphitized product.

Claims (3)

1. A processing method of a graphite bipolar plate of a fuel cell is characterized by comprising the following steps: adopting impregnant to carry out vacuum pressurization impregnation on the fuel cell bipolar plate obtained by pressing, molding and roasting the petroleum coke powder, carrying out secondary roasting treatment on the impregnated fuel cell bipolar plate, carrying out graphitization treatment on the product after the secondary roasting, and then machining the fuel cell graphite bipolar plate;

the impregnant is a mixture of coal pitch and mesocarbon microbeads, and the mixing ratio is coal pitch: the mesocarbon microbeads are 10:1-100: 1;

the vacuum pressure impregnation comprises the following steps:

heating the bipolar plate at 200-400 deg.c, vacuum pumping to-0.07-0.1 MPa, adding impregnant to submerge the bipolar plate completely, and pressurizing the impregnating tank at 1-20 MPa for 1-24 hr.

2. The method of processing a graphite bipolar plate for a fuel cell according to claim 1, wherein: the granularity of the mesocarbon microbeads of said impregnant is 0.5-30 microns.

3. The method of processing a graphite bipolar plate for a fuel cell according to claim 1 or 2, wherein: the processing method comprises the following steps:

petroleum coke powder with different granularities is taken as a raw material, and is molded after being fully stirred, kneaded and kneaded;

secondly, after the formed product is fully cooled, roasting treatment is carried out;

preparing impregnant, wherein the impregnant comprises coal pitch: the intermediate phase carbon microsphere is 50:1, and the granularity of the intermediate phase carbon microsphere is 1-5 mu m;

fourthly, heating the roasted product, wherein the final heating temperature is 320 ℃;

putting the heated product into an impregnation tank, vacuumizing the impregnation tank, keeping the vacuum degree at-0.08 MPa for 30 minutes;

sixthly, injecting the prepared impregnant into an impregnation tank, and completely submerging products to be impregnated;

seventhly, pressurizing the dipping tank, wherein the pressurizing pressure is 5MPa, and the dipping time under the pressurizing is 4 hours;

eighthly, roasting the soaked product;

ninthly, graphitizing the product after roasting;

and (c) performing corresponding machining on the graphitized product.

Images