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CN-122000372-A - Preparation method of phosphoric acid fuel cell electrode

CN122000372ACN 122000372 ACN122000372 ACN 122000372ACN-122000372-A

Abstract

The application relates to the technical field of fuel cell manufacturing and discloses a preparation method of a phosphoric acid fuel cell electrode. The electrode is prepared from a hydrophobic carbon paper substrate and slurry containing a modified graphene oxide thickener, a platinum carbon catalyst and polytetrafluoroethylene. The preparation method comprises the steps of collecting the weight of a substrate in real time before coating and calculating an area density deviation coefficient, performing feedforward control based on the coefficient during coating, adjusting the feed flow or lip gap in real time by utilizing a permeation compensation algorithm to actively compensate local difference of the liquid absorption amount of the substrate, and dynamically adjusting the laser power to carry out trimming by utilizing a visual positioning correction path and based on local thickness data after curing. According to the application, by establishing the real-time feedforward control loop of the physical parameters of the substrate and the coating process, the influence of the non-uniformity of the substrate on the product quality is effectively eliminated, and meanwhile, the modified functional slurry and the precise post-treatment process are combined, so that the internal resistance of the electrode is reduced, and the integrity of the edge microstructure is ensured.

Inventors

  • LU CONG

Assignees

  • 中科润谷智慧能源科技(佛山)有限公司

Dates

Publication Date
20260508
Application Date
20260210

Claims (10)

  1. 1. The phosphoric acid fuel cell electrode is characterized by comprising the following raw materials of a hydrophobic carbon paper base material and a catalyst slurry, wherein the catalyst slurry comprises a solvent and a solid component dispersed in the solvent, the solid component comprises a platinum carbon catalyst, polytetrafluoroethylene and a modified thickener, the total solid content of the catalyst slurry is 15-35 wt%, the dry weight ratio of the platinum carbon catalyst to the polytetrafluoroethylene is 6:4-8:2, the addition amount of the modified thickener is 0.1-0.5% of the total weight of the catalyst slurry, the modified thickener is methoxy polyethylene glycol amine grafted graphene oxide, and the preparation method comprises the steps of activating carboxyl groups by using 1-3-dimethylaminopropyl-3-ethyl carbodiimide hydrochloride and N-hydroxysuccinimide in a graphene oxide dispersion liquid, then adding methoxy polyethylene glycol amine with the number average molecular weight of 1000-5000, reacting at the pH value of 8.0 and the temperature of 60 ℃, and carrying out dialysis and drying.
  2. 2. The method for producing a phosphoric acid fuel cell electrode according to claim 1, comprising the steps of: s1, preparing catalyst slurry, namely dispersing the platinum carbon catalyst, polytetrafluoroethylene dispersion liquid and a modified thickener in a solvent to prepare the catalyst slurry; S2, substrate feeding and data acquisition, namely conveying the hydrophobic carbon paper substrate, acquiring the real-time weight of the substrate in real time, and calculating the surface density deviation coefficient of the current substrate region according to the set reference surface density; S3, surface cleaning pretreatment, namely cleaning and drying the surface of the substrate; S4, self-adaptive dynamic coating, namely coating catalyst slurry on the surface of a substrate, wherein a control system executes feedforward control according to the surface density deviation coefficient in the step 2, and adjusts the flow rate of a coating feed pump or lip gap of a coating head in real time; S5, gradient high-temperature curing, namely sequentially carrying out heat treatment on the coated wet electrode through a solvent volatilizing area, a surfactant removing area and a sintering curing area; s6, laser trimming, namely cutting the cured electrode by utilizing laser.
  3. 3. The method for preparing a phosphoric acid fuel cell electrode according to claim 2, wherein in step 1, the catalyst slurry is prepared by mixing and premixing the components, performing high shear dispersion at a rotation speed of 2000 rpm to 5000 rpm for 30 minutes to 45 minutes, and then performing vacuum defoaming treatment under a negative pressure condition.
  4. 4. The preparation method of the phosphoric acid fuel cell electrode according to claim 2, wherein in the step 3, the surface cleaning pretreatment mode is that deionized water is adopted for atomization spray cleaning, then air knife is adopted for dewatering and infrared drying, the temperature of an infrared drying area is 95-105 ℃, and the water content of a base material before coating is lower than 0.1%.
  5. 5. The method for preparing a phosphoric acid fuel cell electrode according to claim 2, wherein in the step 3, the surface cleaning pretreatment is performed by using a normal pressure plasma cleaning machine to bombard with a mixed gas of argon and oxygen.
  6. 6. The method for preparing the electrode of the phosphoric acid fuel cell according to claim 2, wherein in the step 4, the specific mode of feedforward control is that a basic flow and a permeability compensation coefficient are set, a target flow is calculated by utilizing a permeability compensation algorithm, and a pump speed is regulated, wherein the value range of the permeability compensation coefficient is 0.1-0.5, and the surface density deviation coefficient is the ratio of the real-time surface density of a substrate to the reference surface density.
  7. 7. The method for preparing a phosphoric acid fuel cell electrode according to claim 2, wherein in step 4, the lip gap of the coating head is set to be 60 to 250 micrometers and the wet film thickness is controlled to be 65 to 300 micrometers during the self-adaptive dynamic coating.
  8. 8. The method for preparing a phosphoric acid fuel cell electrode according to claim 2, wherein in step 5, the temperature of the gradient high-temperature curing is set to 80-120 ℃ in a solvent volatilization zone, 240-280 ℃ in a surfactant removal zone and 330-360 ℃ in a sintering curing zone.
  9. 9. The method for preparing a phosphoric acid fuel cell electrode according to claim 2, wherein in step 6, the specific mode of laser trimming includes identifying marked points on the electrode by a vision system, extracting actual coordinates by using Otsu algorithm and performing affine transformation to obtain a corrected cutting path.
  10. 10. The method for preparing an electrode for a phosphoric acid fuel cell according to claim 2, wherein in step 6, local thickness data of the electrode is obtained simultaneously during the laser trimming process, and when the local thickness exceeds 5% of the average value, the laser power is increased by 3%.

Description

Preparation method of phosphoric acid fuel cell electrode Technical Field The invention relates to the technical field of fuel cell manufacturing, in particular to a preparation method of a phosphoric acid fuel cell electrode. Background Phosphoric acid fuel cells are used as a mature power generation technology, and the pore diffusion electrode of the core component is usually formed by compounding hydrophobic carbon paper or carbon cloth base materials with a catalytic functional layer. In the large-scale manufacturing process of the electrode, how to ensure the consistency of the catalyst loading, reduce the internal resistance of the electrode and ensure the machining precision is a key factor for determining the performance and the service life of the cell stack. In existing continuous coating production, the coating equipment typically performs slurry coating at a preset constant feed flow rate and head gap. However, hydrophobic carbon paper or carbon cloth as a substrate belongs to a porous material, and is limited by its own manufacturing process, whose areal density and porosity objectively fluctuate between batches and even different regions of the same web. The traditional fixed parameter coating mode cannot respond to local changes of physical properties of the substrate, and when the porosity or gram weight of the substrate changes, the liquid absorption capacity of the substrate fluctuates, so that the load capacity of the electrode catalyst finally formed deviates. The uneven loading increases the waste of noble metal platinum, and can lead to uneven voltage distribution of the single cells in the cell stack, thereby affecting the overall output performance. In addition, in order to meet the requirements of precise processes such as slot extrusion coating on the rheological properties of the slurry, a thickening agent or a rheological aid, such as cellulose derivatives such as sodium carboxymethyl cellulose or hydroxypropyl methyl cellulose, is generally required to be added to the slurry formulation. Most of such polymer aids belong to electrical insulators, and ash residues or non-conductive carbides are easily formed during high temperature sintering of the electrode, which can block electron transport channels inside the catalytic layer, resulting in an increase of ohmic resistance of the electrode. Meanwhile, high-concentration platinum carbon catalyst particles are easy to agglomerate in slurry, and if a dispersion system lacks effective steric hindrance support, the effective reaction area of a three-phase interface can be reduced by the agglomeration of the catalyst, so that the electrochemical activity of an electrode is limited. In the post-treatment stage of electrode preparation, the cured coiled electrode is typically slit and trimmed by a laser cutting technique. Because the electrode material has certain flexibility, micro-stretching or deflection is easy to generate in the long-distance roller-to-roller conveying process, the traditional mechanical stop block positioning or simple photoelectric alignment mode is difficult to ensure the accurate matching of the cutting path and the actual coating area, and the dimension deviation is easy to cause. On the other hand, the absolute thickness uniformity is difficult to achieve in the prior coating process, and when the cutting is carried out by adopting laser with constant power, the difficulty is faced in that in the thinner coating area, excessive laser energy can cause serious edge carbonization, the heat affected zone is enlarged and even base material fibers are damaged, and in the thicker coating area, the same energy can not be completely cut through, so that the product is difficult to separate or burrs are generated, and the microstructure integrity and the subsequent sealing reliability of the electrode edge are seriously affected. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a preparation method of a phosphoric acid fuel cell electrode, which solves the technical problems that in the prior art, catalyst loading uniformity is poor due to fluctuation of physical characteristics of a hydrophobic carbon paper substrate, electrode internal resistance is increased due to residue of a traditional insulating thickener, and the dimensional accuracy and the edge microscopic quality are difficult to be compatible in the conventional laser cutting process. In order to achieve the above purpose, the invention is realized by the following technical scheme: in a first aspect, the invention provides a phosphoric acid fuel cell electrode prepared from raw materials including a hydrophobic carbon paper substrate and a catalyst slurry. The catalyst slurry comprises a solvent and a solid component dispersed in the solvent, wherein the solid component comprises a platinum carbon catalyst, polytetrafluoroethylene and a modified thickener. The total solid content of the catalyst slurry is controlled to