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CN-122025690-A - Composite modified material of high-toughness graphite bipolar plate and preparation method thereof

CN122025690ACN 122025690 ACN122025690 ACN 122025690ACN-122025690-A

Abstract

The invention relates to the technical field of automobile batteries, in particular to a composite modified material of a high-toughness graphite bipolar plate and a preparation method thereof, wherein intercalation modified graphite is used as a matrix, and a composite reinforcing phase, a toughness modifier, a composite binder and auxiliary additives are added, wherein the components comprise, by weight, 70-85 parts of the intercalation modified graphite matrix, 5-15 parts of the composite reinforcing phase, 3-8 parts of the toughness modifier, 2-6 parts of the composite binder and 0.5-2 parts of the auxiliary additives, and the sum of the components is 100 parts. According to the invention, the composite reinforcing phase and the toughness modifier are used for synergistic effect, the modified nano carbon fiber can form a three-dimensional network structure in the intercalation modified graphite matrix, impact stress is dispersed, the modified ZrO 2 /Al 2 O 3 -graphite microchip composite particles play a role of dispersion strengthening, and the toughness modifier can form an elastic network to absorb impact energy.

Inventors

  • CUI JIN
  • CUI LI
  • ZHANG YU
  • ZHU XIAOLI

Assignees

  • 青岛高等密封制品有限公司

Dates

Publication Date
20260512
Application Date
20260317

Claims (10)

  1. 1. The composite modified material of the high-toughness graphite bipolar plate is characterized in that intercalation modified graphite is taken as a matrix, and a composite reinforcing phase, a toughness modifier, a composite binder and an auxiliary aid are added, wherein the components are, by weight, 70-85 parts of the intercalation modified graphite matrix, 5-15 parts of the composite reinforcing phase, 3-8 parts of the toughness modifier, 2-6 parts of the composite binder and 0.5-2 parts of the auxiliary aid, and the sum of the components is 100 parts; The intercalation modified graphite matrix is formed by mixing ionic liquid intercalation modified natural crystalline flake graphite and modified expandable graphite according to a weight ratio of (3-5): 1; The composite reinforcing phase is formed by mixing silane coupling agent modified carbon nanofiber and dopamine modified ZrO 2 /Al 2 O 3 -graphite microchip composite particles according to the weight ratio of (2-4) to 1; The toughness modifier is prepared by mixing hydroxyl-terminated polybutadiene-polyimide copolymer and polyethylene glycol-catechol phenylborate-polyglutamic acid graft according to the weight ratio of (3-5) to 1; The composite adhesive consists of modified phenolic resin, modified epoxy resin and tetraisobutyl titanate coupling agent, wherein the weight ratio of the modified phenolic resin to the modified epoxy resin is (1.9-2.2): 1, and the tetraisobutyl titanate coupling agent accounts for 0.5-1% of the total mass of the composite adhesive.
  2. 2. The composite modified material of the high-toughness graphite bipolar plate according to claim 1, wherein the particle size of the ionic liquid intercalation modified natural crystalline flake graphite is 50-200 microns, the expansion multiple of the modified expandable graphite is 200-300 times, and the particle size is 100-300 microns.
  3. 3. The composite modified material of the high-toughness graphite bipolar plate according to claim 1, wherein the silane coupling agent modified carbon nanofiber is prepared by ultrasonic modification of a silane coupling agent-ethanol solution with the mass fraction of 5% -10% and has the diameter of 50-100 nm and the length of 5-10 μm; The particle size of the dopamine modified ZrO 2 /Al 2 O 3 -graphite microchip composite particle is 50-100 nm, the weight ratio of ZrO 2 to Al 2 O 3 is 1:1, and the graphite microchip accounts for 10% -15% of the total mass of the composite particle.
  4. 4. The composite modified material of high-toughness graphite bipolar plate according to claim 1, wherein the weight ratio of hydroxyl-terminated polybutadiene to polyimide in the hydroxyl-terminated polybutadiene-polyimide copolymer is (1-2): 1.
  5. 5. The composite modified material of the high-toughness graphite bipolar plate according to claim 1, wherein the modified phenolic resin is a polymer modified by polymerizing 3-ethyleneoxy propylamine and acrolein, and the modified epoxy resin is prepared by polymerizing epoxy resin with 2-methylene-1, 3-propanediol according to a mass ratio of 1 (0.4-0.7) after acrylic acid grafting double bonds.
  6. 6. The composite modified material of the high-toughness graphite bipolar plate according to claim 1, wherein the auxiliary agent comprises a dispersing agent, a defoaming agent, an antioxidant and conductive lubricant graphite micropowder according to the weight ratio of (2-3) (1-2) (1:1); The dispersing agent is polyethylene glycol-400, the defoaming agent is an organosilicon defoaming agent, the antioxidant is 2, 6-di-tert-butyl-p-cresol, and the particle size of the graphite micropowder of the conductive lubricant is 10-20 mu m.
  7. 7. A method for preparing the composite modified material of the high-toughness graphite bipolar plate according to any one of claims 1 to 5, which is characterized by comprising the following steps: S1, preparing an intercalation modified graphite matrix S110, mixing natural crystalline flake graphite with potassium permanganate, performing ultrasonic treatment, dropwise adding a mixed solution of a phosphoric acid aqueous solution and 2-methylacetanilide-citric acid ionic liquid, continuing ultrasonic treatment after dropwise adding, and then washing and drying to obtain ionic liquid intercalated modified natural crystalline flake graphite; S120, preparing modified expandable graphite, namely adding ordinary expandable graphite into a composite impregnating solution for impregnation, filtering and drying to obtain modified expandable graphite; s130, compounding a graphite matrix, namely mixing and drying ionic liquid intercalation modified natural crystalline flake graphite and modified expandable graphite, adding ethanol as a dispersion medium, performing ball milling, and drying to remove ethanol to obtain intercalation modified graphite matrix powder; S2, preparing a composite reinforcing phase S210, preparing modified carbon nanofiber, namely placing the carbon nanofiber into a silane coupling agent-ethanol solution, performing ultrasonic dispersion, stirring reaction, centrifugally separating, washing with ethanol for 3-4 times, and performing vacuum drying for 2-3 hours to obtain the modified carbon nanofiber; S220, preparing a dopamine modified ZrO 2 /Al 2 O 3 -graphite microchip composite particle, namely preparing a Tris-HCl buffer solution, mixing ZrO 2 、Al 2 O 3 with graphite microchip, adding the buffer solution for ultrasonic treatment, adding dopamine powder into the dispersion liquid for stirring reaction, centrifuging, washing with deionized water to be neutral, and drying to obtain the dopamine modified ZrO 2 /Al 2 O 3 -graphite microchip composite particle; S230, mixing the composite reinforcing phase, namely mixing the modified nano carbon fiber and the dopamine modified ZrO 2 /Al 2 O 3 -graphite microchip composite particles according to the weight ratio of (2-4) to 1, and obtaining the composite reinforcing phase after high-speed mixing; S3, preparing a toughness modifier Mixing hydroxyl-terminated polybutadiene-polyimide copolymer and polyethylene glycol-phenylboronic acid catechol ester-polyglutamic acid graft in a weight ratio of (3-5): 1, and stirring for 1-2 hours at room temperature until the mixture is uniform to obtain a toughness modifier; S4, preparing the composite binder 1, Weighing modified phenolic resin and modified epoxy resin according to the weight ratio of (1.9-2.2), adding a tetraisobutyl titanate coupling agent accounting for 0.5-1% of the total mass of the modified phenolic resin and the modified epoxy resin, and stirring the mixture at room temperature until the mixture is uniform to obtain a composite binder; S5, preparing mixed slurry Mixing intercalation modified graphite matrix powder, a composite reinforcing phase, a toughness modifier, a composite binder and auxiliary agents, adding deionized water accounting for 20% -30% of the total weight of each solid component as a dispersion medium, and mixing to obtain mixed slurry; S6, compression molding Preheating a special die for the bipolar plate, pouring mixed slurry, performing compression molding, cooling and demolding to obtain a bipolar plate green body; s7, curing treatment Placing the bipolar plate green body into a vacuum curing furnace, adopting a gradient heating curing process, and cooling to obtain a cured bipolar plate; S8, post-treatment Polishing, trimming and drying the cured bipolar plate to obtain a high-toughness graphite bipolar plate finished product.
  8. 8. The preparation method of the composite modified material of the high-toughness graphite bipolar plate according to claim 7, wherein in the step S110, the mass ratio of the natural crystalline flake graphite to the potassium permanganate is 1 (0.1-0.2), the concentration of the phosphoric acid aqueous solution is 74-90 wt%, and the mass ratio of the phosphoric acid aqueous solution to the 2-methylacetanilide-citric acid ionic liquid is (1.8-2): 1.
  9. 9. The preparation method of the composite modified material of the high-toughness graphite bipolar plate, which is characterized in that in the step S120, the composite impregnating solution comprises, by mass, 2% -4% of phosphoric acid, 2% -3% of modified polyethylene glycol-phenylboronic acid catechol ester-polyglutamic acid, 0.5% -1% of boric acid, 6% -8% of metal ion liquid and the balance of water; The metal ionic liquid is a product of complexing 1-hydroxyethyl-3-methylimidazole chloride salt with diethyl phosphoacetic acid after reacting with ferric chloride; The solid-liquid ratio of the ordinary expandable graphite to the composite impregnating solution is 1g (0.8-1) L.
  10. 10. The method for preparing the composite modified material of the high-toughness graphite bipolar plate according to claim 7, wherein in the step S220, the concentration of the mixture of ZrO 2 、Al 2 O 3 and graphite microplates in the dispersion is 5-8 g/L, and the concentration of dopamine powder in the dispersion is 2-3 g/L; In the step S7, the gradient heating curing process is that the room temperature is heated to 100 ℃, the heating rate is 5 ℃ per minute, the temperature is kept for 1h, the temperature is further heated to 150 ℃, the heating rate is 3 ℃ per minute, the temperature is kept for 2h, the temperature is finally heated to 200 ℃, the heating rate is 2 ℃ per minute, and the temperature is kept for 3h.

Description

Composite modified material of high-toughness graphite bipolar plate and preparation method thereof Technical Field The invention relates to the technical field of automobile batteries, in particular to a composite modified material of a high-toughness graphite bipolar plate and a preparation method thereof. Background The Proton Exchange Membrane Fuel Cell (PEMFC) is used as one of the core power sources of the new energy automobile, has the advantages of high efficiency, cleanness, zero emission and the like, wherein the bipolar plate is a key component of the fuel cell stack and bears important functions of separating reaction gas, collecting and transmitting current, conducting heat, supporting membrane electrodes and the like, and the performance of the bipolar plate directly determines the efficiency, service life and safety of the fuel cell stack. Currently, bipolar plates of automotive fuel cells are mainly classified into two major categories, namely metal bipolar plates and graphite bipolar plates. The metal bipolar plate has the advantages of high mechanical strength, good processing formability and the like, but has the problems of poor corrosion resistance, high interface contact resistance, higher cost and the like, the production difficulty and the cost are increased by modifying through a complex coating process, and the graphite bipolar plate (comprising compact graphite and flexible graphite) has the advantages of good chemical stability, low interface contact resistance, excellent corrosion resistance, relatively low cost and the like, and is one of the main stream choices of the current fuel cell bipolar plate of the new energy automobile. However, the conventional graphite bipolar plate has the inherent defects of large brittleness and poor toughness of graphite, easy cracking and breakage phenomena under the action of vibration and impact in the running process of an automobile and external force in the assembling and carrying processes, gas leakage, serious influence on the normal operation of a fuel cell stack and even potential safety hazard initiation, and meanwhile, the bending resistance of a pure graphite material is insufficient, so that the novel energy automobile is difficult to adapt to the design requirements of light weight and miniaturization of the novel energy automobile, and the application of the novel energy automobile in high-performance automobile fuel cells is limited. In order to solve the above problems, various modification methods are adopted in the prior art to improve the toughness of the graphite bipolar plate, such as adding resin binder, carbon fiber reinforcement, and the like. However, the prior modification technology still has the defects that the brittleness of the partially modified resin is high after the partially modified resin is cured, although the bonding force can be improved to a certain extent, the impact resistance and the bending resistance of the graphite bipolar plate cannot be effectively improved, even the conductivity of the material can be reduced, the carbon fiber reinforcement modification can improve the toughness, the compatibility of the carbon fiber and a graphite matrix is poor, the agglomeration phenomenon is easy to occur, the modification effect is unstable, the preparation process is complex, the production cost is high, and in addition, the corrosion resistance and the sealing performance of the graphite bipolar plate can be sacrificed by the partial modification method, so that the long-term operation requirement of an automobile fuel cell under the acidic, wet and hot working condition can not be met. For example, the flexible graphite bipolar plate disclosed in patent CN114566669B adopts a resin vacuum impregnation process to improve compactness, but the brittleness of the resin is larger after the resin is solidified, so that the bipolar plate has poor bending resistance and uneven stress, and the flexible graphite bipolar plate disclosed in patent CN117410513B improves bending performance through high-temperature puffing modification of graphite staple fibers, but does not perform intercalation treatment on graphite, so that the sealing performance of the bipolar plate is poor. Meanwhile, the prior art lacks a graphite bipolar plate composite modified material which can give consideration to high toughness, high conductivity, excellent corrosion resistance and sealing property, has simple preparation process and controllable cost, and is suitable for large-scale production of automobiles, and a preparation method thereof. Therefore, aiming at the technical pain points that the existing graphite bipolar plate is insufficient in toughness and easy to crack and the performance is difficult to balance in the modification process, the high-toughness graphite bipolar plate composite modified material suitable for the automobile field and the preparation method thereof are developed, and the high-toughness graphite bipolar