Performance recovery method of steel belt fastening type fuel cell
By adjusting the torque of the steel belt bolts and performing under-oxygen activation treatment, the problem of degradation of the durability of the steel belt fastening fuel cell is solved, the mechanical stability and electrochemical performance of the stack are restored, and the use of the stack is extended life.
Patent Information
- Application Number
- CN202411400137.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-09
- Publication Date
- 2025-01-03
AI Technical Summary
The durability of steel belt fastening fuel cells decreases with the increase in use, and it needs to restore its mechanical stability and electrochemical properties.
The durability of the stack is restored by determining the target torque of the steel strip bolt and adjusting it to a uniform actual torque, combined with the preset process of under-oxygen activation and gas metering ratio.
The consistency of the bolt torques of each steel belt fastening fuel cell is achieved, the mechanical stability and electrochemical performance of the stack is restored, the risk of crushing the membrane electrode is reduced, and the service life of the stack is extended.
Smart Images
Figure CN119253014A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of fuel cells, and in particular to a performance recovery method for a steel belt fastened fuel cell. Background Art
[0002] In a steel-belt-fastened fuel cell, the stack is tightly bound together with steel belts on the outside, and each steel belt is fixed with bolts at both ends. Currently, the durability of steel-belt-fastened fuel cells decreases with the increase of usage time, and it is necessary to consider the issue of restoring their durability. Summary of the invention
[0003] The present invention solves the technical problem of how to restore the durability performance of a steel belt fastened type fuel cell by providing a performance recovery method of the steel belt fastened type fuel cell.
[0004] The present invention provides the following technical solutions:
[0005] A method for restoring the performance of a steel belt fastened fuel cell, comprising:
[0006] Determine the target torque of the steel band bolts in the steel band fastened fuel cell;
[0007] The actual torque of each of the steel strip bolts is adjusted to the target torque.
[0008] Optionally, the target torque is lower than the initial torque of the steel strip bolt.
[0009] Optionally, the target torque is higher than the actual torque of the steel strip bolt.
[0010] Optionally, determining the target torque of the steel belt bolts in the steel belt fastened fuel cell includes:
[0011] Determining the service life of the steel belt fastened fuel cell;
[0012] Based on the principle that the target torque is negatively correlated with the usage time, the target torque is determined according to the usage time.
[0013] Optionally, determining the target torque according to the usage time includes:
[0014] The target torque is calculated according to the formula F=AB*t / 1000, where F is the target torque, t is the usage time, A is the initial torque of the steel strip bolt, and B is the constant corresponding to the initial torque.
[0015] Optionally, A=8N·m, B=0.2N·m.
[0016] Optionally, after adjusting the actual torque of each of the steel strip bolts to the target torque, the method further includes:
[0017] Setting the cathode gas stoichiometric ratio of the fuel cell stack of the steel belt fastened fuel cell to a first stoichiometric ratio, performing oxygen-deficient activation on the fuel cell stack and cyclically performing a preset process until the cathode gas stoichiometric ratio drops to a second stoichiometric ratio or the average single-cell voltage of the fuel cell stack reaches a target voltage;
[0018] Wherein, the preset process includes: activating the fuel cell stack with oxygen deficiency for a first preset time; and after the first preset time, reducing the cathode gas stoichiometric ratio.
[0019] Optionally, the target voltage is 0.3V.
[0020] Optionally, the cathode gas stoichiometric ratio of the steel belt fastened fuel cell stack is set to a first stoichiometric ratio, the stack is subjected to oxygen-deficient activation, and a preset process is cyclically performed until the cathode gas stoichiometric ratio drops to a second stoichiometric ratio or the average single-cell voltage of the stack reaches a target voltage, and the method further comprises:
[0021] If the average single-cell voltage of the stack reaches the target voltage, the stack continues to be oxygen-deficiently activated for a second preset time period based on the current cathode gas stoichiometry.
[0022] Optionally, the cathode gas stoichiometric ratio of the steel belt fastened fuel cell stack is set to a first stoichiometric ratio, the stack is subjected to oxygen-deficient activation, and a preset process is cyclically performed until the cathode gas stoichiometric ratio drops to a second stoichiometric ratio or the average single-cell voltage of the stack reaches a target voltage, and the method further comprises:
[0023] The anode gas stoichiometric ratio of the fuel cell stack is set to a preset stoichiometric ratio, the anode gas back pressure and the cathode gas back pressure of the fuel cell stack are both set to preset pressures, the cooling water inlet temperature of the fuel cell stack is set to a preset temperature, the current density of the fuel cell stack is set to a preset density, and the anode gas and cathode gas of the fuel cell stack are both humidified at a preset ratio.
[0024] One or more technical solutions provided by the present invention have at least the following technical effects or advantages:
[0025] The present invention determines the target torque of the steel belt bolts in the steel belt fastened fuel cell, and adjusts the actual torque of each steel belt bolt to the target torque, which is equivalent to adjusting the actual torque of each steel belt bolt of the steel belt fastened fuel cell to be consistent, so that each steel belt applies a uniform binding force to the fuel cell stack, thereby restoring the durability of the fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.
[0027] Figure 1 Schematic diagram of the structure of a steel belt fastened fuel cell in an embodiment of the present invention;
[0028] Figure 2 This is a schematic diagram of the structure of the steel belt and the bolt in the embodiment of the present invention;
[0029] Figure 3 Flow chart of the performance recovery method of the steel belt fastened fuel cell in an embodiment of the present invention.
[0030] Description of reference numerals:
[0031] 10-battery stack, 20-end plate, 30-steel belt, 40-bolt. DETAILED DESCRIPTION
[0032] The embodiment of the present invention solves the technical problem of how to restore the durability performance of a steel belt fastened type fuel cell by providing a performance recovery method of a steel belt fastened type fuel cell.
[0033] In order to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.
[0034] The fuel cell stack of the steel belt fastened type is composed of multiple single cells stacked together, each of which includes a membrane electrode assembly and a bipolar plate. Figure 1 As shown, end plates that are in close contact with the stack are installed at both ends of the stack, and there are multiple parallel steel belts outside the end plates for binding the end plates. Figure 2 As shown, the head and tail ends of each steel belt are fixedly connected with bolts. During the stacking process, the initial torque of each bolt is a uniform constant value, for example, 8N·m, so that each steel belt can apply a uniform binding force to the stack, so that the pressure inside the stack is evenly distributed and the deformation of the stack end plate is reduced, which can not only improve the mechanical stability of the stack, but also reduce the durability degradation caused by uneven pressure.
[0035] In practice, it is found that as the use time of the fuel cell stack increases, the torque of the bolts will decrease due to their inherent characteristics, and the residual torque of each bolt will be different, that is, the torque of each bolt is different. This leads to differences in the binding force of the steel belts at different positions, resulting in uneven stress on the membrane electrode and bipolar plate inside the fuel cell stack, thereby reducing the overall durability of the fuel cell stack.
[0036] To restore the durability of the stack, Figure 3 As shown, the performance recovery method of the steel belt fastened fuel cell in the embodiment of the present invention comprises:
[0037] Step S1, determining a target torque of a steel belt bolt in a steel belt fastened fuel cell;
[0038] Step S2, adjusting the actual torque of each steel strip bolt to the target torque.
[0039] Considering that the reduction in durability of the fuel cell stack is caused by the different torques of each bolt, the durability of the fuel cell stack can be restored to a certain extent as long as the torques of each bolt are kept the same.
[0040] In some embodiments, the target torque may be greater than the initial torque of the bolt. In some embodiments, the target torque may be equal to the initial torque of the bolt, that is, the actual torque of each bolt is restored to the initial state. In some embodiments, the target torque may also be less than the initial torque of the bolt.
[0041] Step S2 adjusts the actual torque of each steel strip bolt to the target torque, which is equivalent to adjusting the actual torque of each bolt to be consistent, thereby restoring the durability of the fuel cell stack.
[0042] In practice, it is also found that as the battery stack is used for a longer time, the membrane electrode inside the battery stack will undergo plastic deformation under the pressure of the steel belt. If the torque of the bolt is restored to the initial torque or greater than the initial torque, the membrane electrode will have a high risk of collapse. To reduce the risk of membrane electrode collapse, in some embodiments, the target torque can be lower than the initial torque of the steel belt bolt. For example, if the initial torque is 8N·m, the target torque can be 7N·m, thereby reducing the risk of membrane electrode collapse due to plastic deformation.
[0043] The embodiment of the present invention collects statistics on the change of the torque of each bolt with the use time, as shown in Table 1.
[0044] Table 1
[0045]
[0046] It can be seen that the torque of each bolt decreases significantly after every 1000 hours of use. If the torque of the bolt is adjusted to be smaller than the current actual torque of the bolt, the mechanical stability of the stack will be greatly reduced. To ensure the mechanical stability of the stack, in some embodiments, the target torque can be higher than the actual torque of the steel strip bolt. For example, for Table 1, the torque of each bolt can be restored to 7 N·m at 1000 hours.
[0047] It is understandable that, considering that the longer the battery stack is used, the stronger the plastic deformation of the membrane electrode may be, if the target torque is set too large when the battery stack is used for a long time, it will lead to a high risk of collapse of the membrane electrode; if the target torque is too small, it will lead to poor mechanical stability of the battery stack. In order to better balance the risk of collapse of the membrane electrode and the mechanical stability of the battery stack, in some embodiments, step S1 may include: determining the service life of the steel belt fastened fuel cell; based on the principle that the target torque is negatively correlated with the service life of the fuel cell, determining the target torque according to the service life of the fuel cell. In some embodiments, the target torque can be 7N·m when the service life is 0-1000h, the target torque can be 6N·m when the service life is 1000-2000h, and the target torque can be 5N·m when the service life is 2000-3000h.
[0048] In some embodiments, the target torque is determined according to the use time of the fuel cell, which may include: calculating the target torque according to the formula F = AB*t / 1000, where F is the target torque, t is the use time, A is the initial torque of the steel strip bolt, and B is the constant corresponding to the initial torque. It is found in practice that when the initial torque of the bolt is 8N·m, reducing the torque of the bolt by 0.2N·m every 1000h can best reduce the risk of collapse of the membrane electrode and improve the mechanical stability of the stack, that is, in some embodiments, A = 8N·m, B = 0.2N·m. Considering that it is not realistic to adjust the bolt torque frequently, the bolt torque can be restored once every 1000h in practice. However, the bolt torque cannot be reduced indefinitely, and the minimum needs to be above 2N·m.
[0049] In some embodiments, the stack needs to be activated regularly to increase the activity of the catalyst in the stack, thereby improving the electrochemical performance of the fuel cell. Oxygen deficiency activation is one of the activation methods, which can remove oxides on the surface of the catalyst and improve the activity of the catalyst. In some embodiments, the cathode gas stoichiometric ratio during the oxygen deficiency activation process is always a constant value, but a higher cathode gas stoichiometric ratio will result in a higher average single-chip voltage of the stack and a slower rate of oxygen deficiency activation; a lower cathode gas stoichiometric ratio may cause the stack to suddenly be in a state of cathode gas deficiency, resulting in the anode voltage of the battery being higher than the cathode voltage, that is, a voltage reversal phenomenon occurs, which may lead to a decrease in battery performance and material damage.
[0050] In order to increase the speed of oxygen deficiency activation and avoid voltage reversal phenomenon, in some embodiments, after step S2, the performance recovery method of the steel belt fastened fuel cell may further include:
[0051] The cathode gas stoichiometric ratio of the steel belt fastened fuel cell stack is set to a first stoichiometric ratio, the stack is activated by oxygen deficiency and a preset process is repeated until the cathode gas stoichiometric ratio drops to a second stoichiometric ratio or the average single-cell voltage of the stack reaches a target voltage; wherein the preset process includes: activating the stack by oxygen deficiency for a first preset time; and reducing the cathode gas stoichiometric ratio after the first preset time.
[0052] The larger the gas stoichiometric ratio and the more sufficient the gas supply, the lower the average monolithic voltage of the stack will be when the cathode is underoxygenated. In some embodiments, the first stoichiometric ratio may be 1.8. In some embodiments, the first preset duration may be 3 minutes. In some embodiments, the preset condition may not exist, and the end condition of undervoltage activation is only when the average monolithic voltage of the stack reaches the target voltage. Considering that the lower the average monolithic voltage of the stack and the faster the activation speed, the greater the possibility of voltage reversal in the stack after the average monolithic voltage of the stack is lower than 0.3V, in some embodiments, the target voltage may be 0.3V, which can ensure rapid activation and avoid voltage reversal. In some embodiments, the second stoichiometric ratio may be 1. In some embodiments, the cathode gas stoichiometric ratio can be gradually reduced according to the change trend of 1.8-1.6-1.4-1.3-1.2-1.1-1, so that the cathode gas stoichiometric ratio that can make the average monolithic voltage of the stack reach 0.3V can be gradually found.
[0053] In order to fully activate the stack when the stack activation speed is fast, in some embodiments, the cathode gas stoichiometric ratio of the stack of the steel belt fastened fuel cell is set to a first stoichiometric ratio, the stack is activated under oxygen, and the preset process is cyclically performed until the cathode gas stoichiometric ratio drops to a second stoichiometric ratio or the average single-chip voltage of the stack reaches the target voltage. The performance recovery method of the steel belt fastened fuel cell may also include: if the average single-chip voltage of the stack reaches the target voltage, the stack is continued to be activated under oxygen for a second preset time at the current cathode gas stoichiometric ratio. In some embodiments, the second preset time can be 10 minutes. For example, if the average single-chip voltage of the stack reaches 0.3V when the cathode gas stoichiometric ratio is 1.1, the under oxygen activation is continued for 10 minutes under the condition that the cathode gas stoichiometric ratio is 1.1.
[0054] In some embodiments, the cathode gas stoichiometric ratio of the steel belt fastened fuel cell stack is set to a first stoichiometric ratio, the stack is activated by oxygen deficiency, and a preset process is cycled until the cathode gas stoichiometric ratio drops to a second stoichiometric ratio or the average single-cell voltage of the stack reaches a target voltage. The performance recovery method of the steel belt fastened fuel cell may also include: setting the anode gas stoichiometric ratio of the stack to a preset stoichiometric ratio, the anode gas back pressure and the cathode gas back pressure of the stack to preset pressures, the cooling water inlet temperature of the stack to a preset temperature, the current density of the stack to a preset density, and humidifying the anode gas and cathode gas of the stack at a preset ratio.
[0055] Among them, the anode gas and cathode gas of the stack are humidified to keep the proton exchange membrane moist and ensure the effective conduction of protons; the gas back pressure helps to improve the diffusion and reaction rate of the gas; the temperature of the cooling water entering the stack directly affects the working temperature of the stack, and a higher temperature of the cooling water entering the stack helps to improve the reaction rate. Considering that insufficient supply of anode hydrogen may lead to an increase in anode potential, a decrease in battery voltage, and even water electrolysis and carbon corrosion, and low gas back pressure may lead to insufficient gas flow rate, insufficient reaction, and decreased battery performance, in some embodiments, the preset metering ratio can be 2, the preset pressure can be 170kPa, the preset temperature can be 78°C, the preset density can be the rated electrical density, and the preset ratio can be 40%, which can optimize the performance of the fuel cell and prevent flooding.
[0056] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.
[0057] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.
Claims
1. A method for restoring the performance of a steel belt fastened fuel cell, characterized in that: include: Determine the target torque of the steel band bolts in the steel band fastened fuel cell; The actual torque of each of the steel strip bolts is adjusted to the target torque.
2. The method for restoring the performance of a steel belt fastened fuel cell according to claim 1, characterized in that: The target torque is lower than the initial torque of the steel strip bolt.
3. The method for restoring the performance of a steel belt fastened fuel cell according to claim 1, characterized in that: The target torque is higher than the actual torque of the steel strip bolt.
4. The method for restoring the performance of a steel belt fastened fuel cell according to claim 1, characterized in that: The method of determining a target torque of a steel belt bolt in a steel belt fastened fuel cell comprises: Determining the service life of the steel belt fastened fuel cell; Based on the principle that the target torque is negatively correlated with the usage time, the target torque is determined according to the usage time.
5. The method for restoring the performance of a steel belt fastened fuel cell according to claim 4, characterized in that: The determining the target torque according to the usage time includes: The target torque is calculated according to the formula F=AB*t / 1000, where F is the target torque, t is the usage time, A is the initial torque of the steel strip bolt, and B is the constant corresponding to the initial torque.
6. The method for restoring the performance of a steel belt fastened fuel cell according to claim 5, characterized in that: A=8N·m, B=0.2N·m.
7. The method for restoring the performance of a steel belt fastened fuel cell according to claim 1, characterized in that: After the actual torque of each of the steel strip bolts is adjusted to the target torque, the method further comprises: Setting the cathode gas stoichiometric ratio of the fuel cell stack of the steel belt fastened fuel cell to a first stoichiometric ratio, performing oxygen-deficient activation on the fuel cell stack and cyclically performing a preset process until the cathode gas stoichiometric ratio drops to a second stoichiometric ratio or the average single-cell voltage of the fuel cell stack reaches a target voltage; Wherein, the preset process includes: activating the fuel cell stack with oxygen deficiency for a first preset time; and after the first preset time, reducing the cathode gas stoichiometric ratio.
8. The method for restoring the performance of a steel belt fastened fuel cell according to claim 7, characterized in that: The target voltage is 0.3V.
9. The method for restoring the performance of a steel belt fastened fuel cell according to claim 7, characterized in that: The method further comprises setting the cathode gas stoichiometric ratio of the steel belt fastened fuel cell stack to a first stoichiometric ratio, performing oxygen-deficient activation on the stack, and cyclically performing a preset process until the cathode gas stoichiometric ratio drops to a second stoichiometric ratio or the average single-cell voltage of the stack reaches a target voltage: If the average single-cell voltage of the stack reaches the target voltage, the stack continues to be oxygen-deficiently activated for a second preset time period based on the current cathode gas stoichiometry.
10. The method for restoring the performance of a steel belt fastened fuel cell according to claim 7, characterized in that: The method further comprises setting the cathode gas stoichiometric ratio of the steel belt fastened fuel cell stack to a first stoichiometric ratio, performing oxygen-deficient activation on the stack, and cyclically performing a preset process until the cathode gas stoichiometric ratio drops to a second stoichiometric ratio or the average single-cell voltage of the stack reaches a target voltage: The anode gas stoichiometric ratio of the fuel cell stack is set to a preset stoichiometric ratio, the anode gas back pressure and the cathode gas back pressure of the fuel cell stack are both set to preset pressures, the cooling water inlet temperature of the fuel cell stack is set to a preset temperature, the current density of the fuel cell stack is set to a preset density, and the anode gas and cathode gas of the fuel cell stack are both humidified at a preset ratio.