Background technology
Fuel cell (Proton Exchange Membrane fuel Cell, abbreviation: PEMFC) be a kind of Blast Furnace Top Gas Recovery Turbine Unit (TRT) that chemical energy in fuel and the oxidant is converted into electric energy by the electrocatalytic reaction on the electrode.Fuel battery double plates is one of fuel cell critical component, and generally it is made up of pole plate and flow field.Ideal bipolar plates should possess the good conductor of electricity, heat, the favorable mechanical performance, and good gas barrier properties, than low-density, characteristics such as good corrosion resistance.In common PEMFC, flow field and pole plate can be one, also can be splits.Research of bipolar plates at present and application mainly concentrate on metallic plate and the graphite powder adhesive mixes on the graphite cake that is pressed into.Adopt research that flexible graphite prepares the bipolar plates that fuel cell uses seldom, and the characteristics of flexible graphite own have determined that it is a kind of material that is suitable as very much fuel battery double plates, main representational document is as follows at present:
Mention the employing flexible graphite plate among the WO0041260 and prepared bipolar plates, this bipolar plates is an earlier molded back encapsulating, adhesive mainly is a polyvinylidene fluoride, preparation technology does not mention in detail, emphasis is in the influence of bipolar plate structure to resistance, bipolar plates adopts double-layer structure, be that hydrogen flow-field plate and water cavity are as a plate, the oxygen flow field plate is as a plate, the two is bonded to and constitutes a bipolar plates together, and shortcoming is the pressing process complexity, and the hydrogen plate is because the flow field, two sides causes difficult forming, fragile, cause the percent defective height like this.
The patent WO0064808 that is declared by Ballard company discloses a kind of dual polar plates of proton exchange membrane fuel cell preparation method, prepared dual polar plates of proton exchange membrane fuel cell can satisfy performance requirement aspect resistance characteristic and the mechanical strength, bipolar plates also is to adopt double-layer structure, be applied to the MK900 of Ballard company series battery, but this patent is poor operability in the sheet material preparation, and unstable properties, main defective is the mode of sheet material impregnating resin, it is under normal pressure, the sheet material of certain density sunk in the resin with certain speed flood, because the porosity of the inhomogeneities of sheet material itself and the difference of particle surface and sheet material is different, cause the inhomogeneities of resin diffusion and absorption easily, and the gas permeability of bipolar plates is higher relatively, must increase the hydrogen system that disappears when causing this bipolar plates to be applied to fuel battery engines like this, so just increase the complexity and the unsteadiness of system.
Summary of the invention
The purpose of this invention is to provide the diffusion of a kind of resin evenly, adsorbability is good, to the good airproof performance of gas, with the bipolar board for new proton exchange film fuel battery preparation technology that contact resistance is little, mechanical performance might as well, be easy to produce in batches of Proton Exchange Membrane Fuel Cells diffusion layer carbon paper.
The technical solution adopted for the present invention to solve the technical problems is as follows:
With the graphite ore is raw material, through acidification, reach 150~350ml/g at 800 ℃~1000 ℃ high temperature down to volume, makes expansible graphite; By weight percentage, in expansible graphite, evenly mix the needlestone powder of 7~10wt%, the expanded graphite that is mixed with the needlestone powder is carried out roll-in, make low-density sheet material; Be to flood under-0.08~0.1Mpa the low-density expanded graphite cake by the thermosetting resin mixed liquor, in vacuum degree again; Expanded graphite behind the dipping dried by the fire 2~5 hours under 90 ℃~100 ℃ bake out temperature, and the sheet material of oven dry is through roll-in, and obtaining density is 1.0~1.4g/cm
3Thin graphite flat board; After processing of cutting, mold pressing or roll-forming and settable cementitious processing form bipolar plates;
Described two described needlestone powder can be tremolite powder, calcite in powder or wollastonite in powder, and its granularity is 80~100 orders; Described thermosetting resin mixed liquor is got 1~20wt% phenolic aldehyde, epoxy, furans and/or urea aldehyde, is solvent with 80~99wt% ethanol; Wherein: phenolic aldehyde can be 1~20wt% for 5~20wt%, epoxy resin, and furans can be 5~20wt%, and urea aldehyde can be 5~20wt%; Described fuel battery double plates can be 2 layers to 7 layers structure;
Described 7 layers of structure bipolar plates are by anode flow field, cathode flow field, the anode seal frame, the anode frame pad, anode is cut apart plate, the water plate, negative electrode is cut apart plate, negative electrode frame pad, negative electrode sealing frame is formed, the anode seal frame, the anode frame pad constitutes cavity, negative electrode frame pad, negative electrode sealing frame constitutes cavity, anode flow field, cathode flow field is embedded in the anode seal frame respectively, cavity and negative electrode frame pad that the anode frame pad is formed, in the cavity that negative electrode sealing frame is formed, the anode seal frame, the anode frame pad, anode is cut apart plate, the water plate, negative electrode is cut apart plate, negative electrode frame pad, negative electrode sealing frame sets gradually; Described 6 layers of structure bipolar plates technology are water plate and negative electrode to be cut apart plate or water plate and anode cut apart plate or the water plate is cut apart plate, negative electrode with anode respectively in two and cut apart plate and lump together with a slice plate and realize that all the other plates remain unchanged, and constitute 6 laminates; Described 5 layers of structure bipolar plates technology are that anode seal frame and anode frame pad and negative electrode frame pad and negative electrode sealing frame are realized with a slice plate that respectively same seven laminates of other plate are the same, constitute 5 laminates; Described 4 layers of structure bipolar plates technology are to be about to water plate and negative electrode cut apart plate or water plate and anode and cut apart plate or the water plate is cut apart plate, negative electrode with anode respectively in two and cut apart plate and lump together with a slice plate and realize, anode seal frame and anode frame pad and negative electrode frame pad and negative electrode sealing frame are realized with a slice plate respectively, 4 laminates are bonded to together get final product; Described 3-tier architecture bipolar plates technology is anode seal frame, anode frame pad, anode to be cut apart plate and negative electrode cut apart plate, negative electrode frame pad, negative electrode sealing frame and be incorporated into respectively together, is bonded to together in the water plate then; Anode seal frame, anode frame pad, anode are cut apart plate and are incorporated into and become the hydrogen plate together, and negative electrode is cut apart plate, negative electrode frame pad, negative electrode sealing frame and is incorporated into and becomes the oxygen plate together; Described 2 layers of structure bipolar plates technology are that water plate and hydrogen plate are incorporated into together, stick together with the oxygen plate then; Or water plate and oxygen plate be incorporated into together, stick together with the hydrogen plate then.
The present invention has following beneficial effect:
1. technology is simple.In expansible graphite, mix the needlestone powder, mix, easy to operate, and adopt mold pressing or roll-forming, technology is simple.
2. the resin diffusion is even, and adsorbability is good.Because the present invention adopts phenolic aldehyde, epoxy resin and ethanol hybrid resin, dipping low-density expanded graphite cake, institute is so that resin spreads in the graphite cake hole evenly, and adsorbability is good, and the intensity of plate and gas permeability all have significantly to be improved.
3. good mechanical property.Evenly mix 7~10% needlestone powder in the expansible graphite, destroy the layer structure of graphite cake, its physical property is improved.
4. be evenly distributed.The present invention adopts the vacuum method impregnating resin, and its resin weightening finish is stablized, is evenly distributed.
5. to the good airproof performance of gas.The present invention adopts drawing method to prepare flexible graphite sheet material, and its sealing property to gas is improved greatly, and is little with the contact resistance of Proton Exchange Membrane Fuel Cells diffusion layer carbon paper.
6. has the industrialization meaning.The present invention makes dual polar plates of proton exchange membrane fuel cell, can be 2~7 layers of different structure, and its impregnating resin is selected the mixed solution between thermosetting resin cheaply and these resins for use, can reduce cost; The low-density expanded graphite cake is made the required bipolar plates of fuel cell, and operating equipment is simple, easily large-scale production.
Embodiment
Below in conjunction with drawings and Examples the present invention is described in further detail.
Embodiment 1
The production technology that the present invention adopts adopts the natural flake graphite raw material as shown in Figure 1, makes expansible graphite through conventional acidification, and expansible graphite is instantaneous expansion in 800 ℃ high temperature furnace, reaches 350ml/g to allowance for expansion; Evenly mixed needlestone powder (present embodiment employing tremolite powder) in expansible graphite, its ratio is 10%, and the particle mean size of needlestone powder is 100 orders, and the expanded graphite that is mixed with the needlestone powder is carried out roll-in (known technology), system 0.25g/cm
3Low-density sheet material (low-density refers generally to be lower than 1.0), sheet metal thickness is determined according to the requirement of bipolar plates, generally between 3~10mm (present embodiment is 10mm), rolling equipment adopts general flexible graphite paper production line; The low-density expanded graphite cake is flooded again, impregnating resin is selected thermosetting resin for use, as resin and their mixed solutions according to a certain percentage such as phenolic aldehyde, epoxy, furans, urea aldehyde, (present embodiment adopts phenolic aldehyde 20wt%, ethanol 80wt% to mix the mixed liquor that forms, be immersed in the special-purpose vacuum impregnation case and carry out, dipping vacuum degree is-0.08Mpa that the expanded graphite behind the dipping dried by the fire 2 hours under 90 ℃ bake out temperature, the sheet material of oven dry is through roll-in, and obtaining density is 1.4g/cm
3Thin graphite cake.The water flow field of bipolar plates then adopts this flat board to carry out processing of cutting; The hydrogen-oxygen flow-field plate also utilizes this plate through mold pressing or roll-forming, and the sheet material after the moulding is through 150 ℃ cured, and the sheet material after the curing sticks with glue agent again or glued membrane is bonded to together, becomes the complete bipolar plates of a slice.
The present invention has simplified production technology owing to adopted mold pressing or roll-forming; Adopt phenolic aldehyde, epoxy resin and ethanol hybrid resin, both increased the intensity of bipolar plates, reduced the permeability of gas again, and reduced cost.Wherein hot strength can reach more than the 30MPa, and bending strength can reach more than the 50MPa; Air permenbility is less than 10
-6Cm
3/ cm
2.s, can satisfy the needs of fuel cell fully.
Fuel battery double plates is by 2 layers to 7 layers different structure, (see accompanying drawing 2, present embodiment is 7 layers of structure);
By anode flow field a, cathode flow field b, anode seal frame 1, anode frame pad 2, anode is cut apart plate 3, water plate 4, negative electrode is cut apart plate 5, negative electrode frame pad 6, negative electrode sealing frame 7 is formed, anode seal frame 1, anode frame pad 2 constitutes cavity, negative electrode frame pad 6, negative electrode sealing frame 7 constitutes cavity, anode flow field a, cathode flow field b is embedded in anode seal frame 1 respectively, cavity and negative electrode frame pad 6 that anode frame pad 2 is formed, in the cavity that negative electrode sealing frame 7 is formed, anode seal frame 1, anode frame pad 2, anode is cut apart plate 3, water plate 4, negative electrode is cut apart plate 5, negative electrode frame pad 6, negative electrode sealing frame 7 bonds together successively.
Can select different structures as required, in general, consider the ability and the expense of equipment, mainly be the pressure limit of forcing press or roll squeezer, if the area of required bipolar plates is at 500cm
2Below, select 2 or 3 veneer structures for use, the flow field with cut apart plate, sealed frame and frame pad and be integral; If required bipolar plates area surpasses 500cm
2, generally select 4~7 layers of structure for use, the flow field is preparation separately.
By the foregoing invention design, having designed with the flexible graphite is flow-field plate multikilowatt H
2/ air Proton Exchange Membrane Fuel Cells group, phenolic aldehyde (5wt%), epoxy resin (1wt%) and ethanol (94wt%) proportionally, the parallel groove flow field is adopted in the flow field, 7 layers of structure, electrode area is 573cm
2, battery is 2 joints, catalyst Pt load amount 0.4mg/cm
2Battery average behavior curve and is contrasted with the performance of the battery pack that adopts the copper bipolar plates as shown in Figure 3.
Embodiment 2
Difference from Example 1 is:
Expansible graphite is instantaneous expansion in 1000 ℃ high temperature furnace, reaches 150ml/g to allowance for expansion; Evenly mixed needlestone powder (present embodiment employing calcite in powder) in expansible graphite, its ratio is 7%, and the particle mean size of needlestone powder is 8 orders, and the expanded graphite that is mixed with the needlestone powder is carried out roll-in, makes 0.18g/cm
3Low-density sheet material, sheet metal thickness determines that according to the requirement of bipolar plates present embodiment is 3mm; Impregnating resin selects for use thermosetting resin to adopt phenolic aldehyde (5wt%), alcohol 95 wt% to mix the mixed liquor that forms, dipping vacuum degree is 0.1Mpa, expanded graphite behind the dipping dried by the fire 5 hours under 100 ℃ bake out temperature, and the sheet material of oven dry is through roll-in, and obtaining density is 1.0g/cm
3Thin graphite cake.Sheet material after the moulding is through 200 ℃ cured.
As shown in Figure 4, present embodiment is the H of flow-field plate 3-tier architecture with the flexible graphite
2/ Air Proton Exchange Membrane Fuel Cells group is an example.Its 3 veneer structure is anode seal frame 1, anode frame pad 2, anode to be cut apart plate 3 and negative electrode cut apart plate 5, negative electrode frame pad 6, negative electrode sealing frame 7 and be incorporated into respectively together, is bonded to together in water plate 4 then; Anode seal frame 1, anode frame pad 2, anode are cut apart plate 3 and are incorporated into and become the hydrogen plate together, and negative electrode is cut apart plate 5, negative electrode frame pad 6, negative electrode sealing frame 7 and is incorporated into and becomes the oxygen plate together; With the flexible graphite is the H of flow-field plate 3-tier architecture
2/ Air Proton Exchange Membrane Fuel Cells group, phenolic aldehyde (10wt%), epoxy resin (10wt%) and ethanol (80wt%) proportionally, the parallel groove flow field is adopted in the flow field, utilance>40%, electrode area are 350cm
2, battery is 4 joints, catalyst Pt load amount 0.4mg/cm
2Battery average behavior curve as shown in Figure 4.And contrast with the performance of the battery pack that adopts the copper bipolar plates.
Embodiment 3
Difference from Example 1 is:
Expansible graphite is instantaneous expansion in 900 ℃ high temperature furnace, reaches 200ml/g to allowance for expansion; Evenly mix needlestone powder (present embodiment employing wollastonite in powder) in expansible graphite, its ratio is 8%, and particle mean size is 90 orders, and the expanded graphite that is mixed with the needlestone powder is carried out making 0.2g/cm after the roll-in
3Low-density sheet material, sheet metal thickness 7mm; Impregnating resin selects for use thermosetting resin to adopt 1wt%, epoxy resin, ethanol 99wt% mixes the mixed liquor that forms, dipping vacuum degree is 0.05Mpa, and the expanded graphite behind the dipping dried by the fire 4 hours under 95 ℃ bake out temperature, and it is 1.2g/cm that the sheet material of oven dry obtains density through roll-in
3Thin graphite cake.Sheet material after the moulding is through 180 ℃ cured.
As shown in Figure 5, present embodiment is 2 veneer structures, and it is that water plate 4 and hydrogen plate are incorporated into together, sticks together with the oxygen plate then; Or water plate 4 and oxygen plate be incorporated into together, stick together with the hydrogen plate then; Or water plate 4 lumped together with oxygen plate, hydrogen plate respectively in two.With the flexible graphite is the H of 2 layers of structure of flow-field plate
2/ Air Proton Exchange Membrane Fuel Cells group, phenolic aldehyde (20wt%), epoxy resin (20wt%) and ethanol (60wt%) proportionally, the parallel groove flow field is adopted in the flow field, utilance>40%, electrode area are 128cm
2, battery is 4 joints, catalyst Pt load amount 0.4mg/cm
2, made life experiment, stable operation is 400h nearly, and decay does not significantly appear in battery performance, has confirmed that further this plate can meet the demands fully.Curve is seen Fig. 5.
Embodiment 4
Difference from Example 1 is:
Evenly mix needlestone powder (present embodiment employing wollastonite in powder) in expansible graphite, its ratio is 9%, and particle mean size is 95 orders, and the expanded graphite that is mixed with the needlestone powder is carried out making 0.22g/cm after the roll-in
3Low-density sheet material, sheet metal thickness 8mm; Impregnating resin selects for use thermosetting resin to adopt 15wt% furans, ethanol 85wt% to mix the mixed liquor that forms.
Water plate 4 and negative electrode are cut apart plate 5 or water plate 4 and anode cut apart plate 3 or water plate 4 is cut apart plate 3, negative electrode with anode respectively in two and cut apart plate 5 and lump together with a slice plate and realize that all the other plates remain unchanged, constitute 6 laminates.
Embodiment 5
Difference from Example 1 is:
Evenly mix needlestone powder (present embodiment employing wollastonite in powder) in expansible graphite, its ratio is 9%, and particle mean size is 95 orders, and the expanded graphite that is mixed with the needlestone powder is carried out making 0.22g/cm after the roll-in
3Low-density sheet material, sheet metal thickness 8mm; Impregnating resin selects for use thermosetting resin to adopt the 10t% furans, and ethanol 90wt% mixes the mixed liquor that forms.Anode seal frame 1 and anode frame pad 2 and negative electrode frame pad 6 and negative electrode sealing frame 7 are realized with a slice plate that respectively same 7 laminates of other plate are the same, constitute 5 laminates.
Embodiment 6
Difference from Example 1 is:
Evenly mix needlestone powder (present embodiment employing wollastonite in powder) in expansible graphite, its ratio is 9%, and particle mean size is 95 orders, and the expanded graphite that is mixed with the needlestone powder is carried out making 0.22g/cm after the roll-in
3Low-density sheet material, sheet metal thickness 8mm; Impregnating resin selects for use thermosetting resin to adopt 20wt% urea aldehyde, and ethanol 80wt% mixes the mixed liquor that forms.
Present embodiment is 4 veneer structures, it is with the realization that combines of 6 laminates and 5 veneer structures, being about to water plate 4 and negative electrode cuts apart plate 5 or water plate 4 and anode and cuts apart plate 3 or water plate 4 is cut apart plate 3, negative electrode with anode respectively in two and cut apart plate 5 and lump together with a slice plate and realize, anode seal frame 1 and anode frame pad 2 and negative electrode frame pad 6 and negative electrode sealing frame 7 are realized with a slice plate respectively, four layers are done to be bonded to together getting final product.