CN116706147A - Method for activating fuel cell stack - Google Patents
Method for activating fuel cell stack Download PDFInfo
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- CN116706147A CN116706147A CN202310914877.0A CN202310914877A CN116706147A CN 116706147 A CN116706147 A CN 116706147A CN 202310914877 A CN202310914877 A CN 202310914877A CN 116706147 A CN116706147 A CN 116706147A
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- 238000000034 method Methods 0.000 title claims abstract description 39
- 239000000446 fuel Substances 0.000 title claims abstract description 34
- 230000003213 activating effect Effects 0.000 title claims description 10
- 230000004913 activation Effects 0.000 claims abstract description 98
- 230000008859 change Effects 0.000 claims description 32
- 230000002829 reductive effect Effects 0.000 claims description 22
- 230000008569 process Effects 0.000 claims description 10
- 230000009467 reduction Effects 0.000 claims description 6
- 230000000087 stabilizing effect Effects 0.000 claims description 5
- 230000003247 decreasing effect Effects 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 abstract description 17
- 229910052739 hydrogen Inorganic materials 0.000 abstract description 17
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 16
- 238000001994 activation Methods 0.000 description 94
- 238000006243 chemical reaction Methods 0.000 description 22
- 239000003054 catalyst Substances 0.000 description 17
- 239000007789 gas Substances 0.000 description 16
- 230000000694 effects Effects 0.000 description 11
- 239000012528 membrane Substances 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000006722 reduction reaction Methods 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- MUMZUERVLWJKNR-UHFFFAOYSA-N oxoplatinum Chemical compound [Pt]=O MUMZUERVLWJKNR-UHFFFAOYSA-N 0.000 description 2
- 229910003446 platinum oxide Inorganic materials 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000002484 cyclic voltammetry Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- -1 hydrogen ions Chemical class 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M8/00—Fuel cells; Manufacture thereof
- H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
- H01M8/04223—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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- Sustainable Energy (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Fuel Cell (AREA)
Abstract
The application provides a stack activation method of a fuel cell, which belongs to the field of fuel cells and specifically comprises a plurality of activation cycles, wherein when the difference of voltage record data of two adjacent cycles is smaller than a preset voltage difference value, the completion of activation is judged, each cycle comprises the steps of starting, changing load, outputting large current and stopping, and each activation cycle is once, and the first current density value, the second current density value and the fourth current density value are all larger than the values of the last activation cycle. By adopting the treatment scheme of the application, the activation time of the galvanic pile can be effectively shortened, and the hydrogen consumption can be saved.
Description
Technical Field
The application relates to the field of fuel cells, in particular to a stack activation method of a fuel cell.
Background
At present, the existing fuel cell electric pile (hereinafter referred to as electric pile) activation method mostly adopts a constant voltage or constant current natural activation mode, and the electric pile is wetted by the water produced by the electric pile. This activation is time consuming and is not conducive to rapid activation and mass production. If the stack is activated by cyclic voltammetry, a humidified gas is provided: the method is long in time consumption, increases the complexity of operation and increases the overall cost. In addition, in the current electric pile activation method, an activation strategy for realizing self-adjustment aiming at different electric piles is not available, and the phenomenon of insufficient activation or waste of test resources is often caused.
Disclosure of Invention
Therefore, in order to overcome the disadvantages of the prior art, the present application provides a method for activating a fuel cell stack, which can effectively shorten the stack activation time, save the hydrogen consumption, effectively save the cost and improve the stack activation efficiency of the fuel cell.
In order to achieve the above object, the present application provides a stack activation method of a fuel cell, including a plurality of activation cycles, in which when a difference between voltage record data of two adjacent cycles is smaller than a preset voltage difference value, it is determined that activation is completed, each activation cycle including the steps of: step one, starting a galvanic pile of a fuel cell, loading current to enable the density of the galvanic pile to reach an initial preset value, wherein the change rate of the loaded current is 0.05A/(cm x s) to 0.15A/(cm x s); after the current is stabilized, the current density is increased from the initial preset value to a first current density value, the load current density change rate is 0.10A/(cm & lts & gt) to 0.30A/(cm & lts & gt), then the load current density is reduced to a second current density value, the load reduction current density change rate is 0.20A/(cm & lts & gt to 0.40A/(cm & lts & gt), and the first current density value is more than the second current density value is more than the initial preset value; step three, the current density is increased from the second current density value to the first current density value, the load current density change rate is 0.10A/(cm, s) to 0.30A/(cm, s), then the load current density is reduced to the second current density value, the load reduction current density change rate is 0.20A/(cm, s) to 0.40A/(cm, s), and the repetition number of the second current density loaded to the first current density value and then reduced to the second current density is 2 to 4. Step four, increasing the current density from the second current density value to the first current density value, wherein the load current density change rate is 0.10A/(cm & lts & gt) to 0.30A/(cm & lts & gt), and then reducing the load current density from the first current density value to a third current density value, and the load shedding current density change rate is 0.20A/(cm & lts & gt) to 0.40A/(cm & lts & gt). Repeating the following steps for 1-3 times: increasing the current density from the third current density value to the first current density value, then decreasing the current density to the second current density value, and repeating the processes from the third step to the fourth step; step six, after the current density is increased from the third current density value to the fourth current density value, the load current density change rate is 0.10A/(cm < n >. S) to 0.30A/(cm < n >) and the current is stabilized for a preset time, and the voltage value at the moment is recorded; and step seven, reducing the current density from the fourth current density value to the third current density value, then closing air supply at the cathode side, and shutting down, wherein each activation cycle is performed once, and the first current density value, the second current density value and the fourth current density value are all larger than the value of the last activation cycle.
In one embodiment, the test conditions in the cycle are controlled prior to each activation cycle, the test conditions including fuel cell temperature, gas pressure and/or gas humidity, the fuel cell temperature range being 75-85 ℃, the gas relative humidity range being 60% -90%, and the gas pressure control range being 100 kpa-200 kpa.
In one embodiment, the initial preset value is 0.1-0.6A/cm, the first current density value is 1.6-2.2A/cm, the second current density value is 1.0-1.6A/cm, the third current density value is 0.2-0.8A/cm, and the fourth current density value is 2.0-3.0A/cm.
In one embodiment, the air supply to the cathode side is turned off, a small current is applied for an additional few seconds, not more than 30 seconds, and the current density of the small current is preferably in the range of 0.02 to 0.1A/cm, and then the shutdown is performed.
In one embodiment, the preset voltage difference is 3-10 mV.
In one embodiment, the current preset time is 30-300 s.
In one embodiment, in the second step, after the current is stabilized, the current is stabilized for a period of several seconds, and the range of the stabilizing period is 30 s-500 s.
Compared with the prior art, the application has the advantages that: the catalyst which does not participate in the reaction can be activated and the structure of the catalytic electrode can be optimized; and the electrolyte in the membrane electrode is fully hydrated, so that the resistance of mass transfer is reduced; reducing the platinum oxide attached to the cathode surface by a shutdown strategy that stops the cathode side air supply; meanwhile, air is consumed, and oxidation reaction after shutdown is blocked; by judging the fixed point voltage, the number of times of pile activation is self-adaptive, so that the cost can be effectively saved and the activation effect can be improved. The activation strategy of the application can effectively shorten the activation time of the galvanic pile and save the hydrogen consumption; the self-adaption of different electric pile activation time and times can be realized, the cost can be effectively saved, and the effect of activating the fuel cell electric pile can be improved; meanwhile, the activation process comprises a start-stop strategy, so that the oxide on the cathode side can be effectively removed.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a current density variation diagram of a stack activation method of a fuel cell in an embodiment of the application;
FIG. 2 is a flow chart of a method of stack activation of a fuel cell in an embodiment of the application;
FIG. 3 is a graph comparing voltage and power before and after stack activation of a fuel cell in an embodiment of the application;
FIG. 4 is a graph of activation efficiency after multiple cycles of a stack of fuel cells in an embodiment of the application;
fig. 5 is a current density variation diagram of a stack activation method of a fuel cell in another embodiment of the present application.
Detailed Description
Embodiments of the present application will be described in detail below with reference to the accompanying drawings.
Other advantages and effects of the present application will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present application with reference to specific examples. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. The application may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present application. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, apparatus may be implemented and/or methods practiced using any number and aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
It should also be noted that the illustrations provided in the following embodiments merely illustrate the basic concept of the present application by way of illustration, and only the components related to the present application are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.
In addition, in the following description, specific details are provided in order to provide a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.
As shown in fig. 1, an embodiment of the present application provides a stack activation method for a fuel cell, including a plurality of activation cycles, each cycle including a start-up, a load-change, a high current output, and a shutdown step.
And in the multiple cycles, when the difference between the voltage record data of two adjacent cycles is smaller than a preset voltage difference value, judging that the activation is completed, ending the activation flow, avoiding excessive activation, reducing the activation time, saving the test resources and reducing the hydrogen loss. The degree of activation is automatically judged and the number of activation cycles is determined by comparing and analyzing the performance of the fixed point in each activation cycle. And whether the activation is completed or not is flexibly judged according to the difference of voltage record data of two adjacent cycles, so that the application scene of the galvanic pile activation method is widened.
The first current density value, the second current density value and the fourth current density value are all larger than the value of the previous cycle once. When the electric pile is not activated or is insufficiently activated, the forced output current can cause poor consistency of each voltage of the electric pile, and when serious, the electric pile can cause local counter electrode and local battery damage. The current density of activation is gradually increased by turns, so that the situation that the electric pile is forced to output fixed power when not activated or when not activated sufficiently can be avoided, and the electric pile is ensured not to be damaged; on the other hand, the activation density point (activated current density) gradually approaches to a fixed working point, the activation efficiency is accelerated, the activation time and the hydrogen loss are reduced, and the final performance of the electric pile is optimized.
Each activation cycle took about 15 minutes, and each activation cycle included the following steps:
step one, starting a cell stack of the fuel cell, loading current to enable the density of the cell stack to reach an initial preset value, wherein the change rate of the loaded current is 0.05A/(cm x s) to 0.15A/(cm x s).
And secondly, after the current is stabilized, the current density is increased to a first current density value from an initial preset value, the load current density change rate is 0.10A/(cm & lts) & gt to 0.30A/(cm & lts) & gt, then the current is reduced to a second current density value, the load shedding current density change rate is 0.20A/(cm & lts) & gt to 0.40A/(cm & lts) & gt, and the first current density value is larger than the second current density value and larger than the initial preset value.
And thirdly, increasing the current density from the second current density value to the first current density value, wherein the load current density change rate is 0.10A/(cm & ltth & gt, s) & lt 0.30 & gt A/(cm & ltth & gt, then reducing the current density to the second current density value, the load shedding current density change rate is 0.20A/(cm & ltth & gt, s) & lt 0.40 & lt A & gt/(cm & ltth & gt), and the repetition number of loading the second current density to the first current density value and then reducing the load to the second current density is 2-4 times.
The second and third steps adopt to reduce and raise its output power fast, make water and temperature of its catalyst surface detain in the reaction interface on the one hand, can't follow the output power and change in time, the reaction takes place under high temperature, high humidity, increase its reaction rate, make its activating effect more fully; on the other hand, the whole activation process time can be shortened and the production efficiency can be improved by a specific rapid load and unload mode. Under high output power, the heat and water production rate of the electric pile is obviously improved. On one hand, the output power of the catalyst is rapidly reduced, so that water and temperature on the surface of the catalyst are retained at a reaction interface and cannot be converted in time along with the output power. At the moment, under the condition of low output power, the electric pile does not need to perform the process of low-medium-high density gradual activation, shortens the activation time under lower density and the time for waiting for the condition of the electric pile reaction to reach, and realizes rapid temperature rise and humidification. The reaction is carried out under the conditions of high temperature and high humidity, the reaction efficiency is improved, the proton exchange membrane is fully hydrated, and the mass transfer resistance is reduced; on the other hand, through the fast reduction and rising electric pile output, avoid the electric pile when not activating and the activation is incomplete, force the long-time output heavy current under higher power, lead to the electric pile uniformity poor, cause local antipole, battery damage's condition to take place when serious. And the situation that the galvanic pile runs for a long time under the conditions of high humidity and low power to form flooding and undergassing is avoided, and carbon corrosion is seriously caused. Meanwhile, by the specific rapid loading and unloading mode, the electric pile can rapidly circulate among different electric potentials, the catalyst which does not participate in the reaction is rapidly activated, the structure of the catalytic electrode is optimized, the whole activation process is shortened, and the production efficiency is improved.
And step four, increasing the current density from the second current density value to the first current density value, wherein the load current density change rate is 0.10A/(cm & lts & gt) to 0.30A/(cm & lts & gt), and then reducing the load current density from the first current density value to the third current density value, and the load reduction current density change rate is 0.20A/(cm & lts & gt) to 0.40A/(cm & lts & gt.
Repeating the following steps for 1-3 times: and (3) increasing the current density from the third current density value to the first current density value, then reducing the current density to the second current density value, and repeating the processes from the third step to the fourth step.
One completion is to increase the current density from the third current density value to the first current density value and then decrease to the second current density value and repeat steps three through four. In the fifth step, 1-3 completed processes can exist. And step two and step three realize high, medium and low potential circulation through large variable load and small variable load circulation, activate the catalyst activity and activate the catalyst which does not participate in the reaction.
Step six, after the current density is increased from the third current density value to the fourth current density value, the load current density change rate is 0.10A/(cm < x s >) to 0.30A/(cm < x s >), the current is stabilized for a preset time, and the voltage value at the moment is recorded. Through the output of large current, a large amount of water is generated to wet the proton exchange membrane. And step six, further stabilizing the activated catalyst, controlling the stable operation of the reactor, and providing reference voltage for the follow-up activation.
And step seven, reducing the current density from the fourth current density value to the third current density value, controlling the duration of the current density staying at the third current density value within 5-60 s, and then closing the air supply at the cathode side to shut down. By stopping the shutdown strategy of air supply only at the cathode side, hydrogen at the anode side is still supplied, when the air supply is closed, the oxidant is lost, so that the reaction process in the electric pile is lagged behind the gas supply, the whole electric pile system is still in the reaction process, the hydrogen is oxidized at the anode side to form ions to pass through a membrane, the ions are reduced again to hydrogen at the cathode side, the generated hydrogen reacts with an oxide layer on the electrode surface to reduce the oxide on the surface, the catalyst activity is improved, the hydrogen is decomposed into hydrogen ions through a membrane electrode to react with the oxide on the cathode side, the oxide layer on the surface of the electrode is reduced, and the redundant air on the air side is consumed, so that the cathode side is in a nitrogen protection state. By the arrangement, not only is the cathode oxide consumed, but also the number of the catalysts participating in the electrochemical reaction is increased, so that the effect of activating the galvanic pile is accelerated, and the efficiency of activating the galvanic pile is improved.
Although the current density loading density change rate is 0.10A/(cm < s >) to 0.30A/(cm < s >) and the load shedding density change rate is 0.20A/(cm < s >) to 0.40A/(cm < s >), the specific value of the current density loading density change rate can be adjusted according to the technological condition in the steps two to six, and the value can be consistent or inconsistent. The current lifting process can be uniform lifting or variable-speed lifting.
In fig. 1, in the first to fifth steps, if not specifically noted, after reaching each peak value or valley value, the current can be controlled to be stable for 1 to 3 seconds, so that time can be saved, and the active point can be ensured to be activated smoothly. When the current density is the first current density value, a larger value may be selected from the range of values, i.e. the larger the current density, the longer the waiting time may be.
In the method, the activation time can be effectively shortened by a specific rapid loading and unloading mode, and the activation time is less than 1h; in addition, the high, medium and low potential circulation is adopted, so that the catalyst which does not participate in the reaction can be activated, and the structure of the catalytic electrode can be optimized; and the electrolyte in the membrane electrode is fully hydrated, so that the resistance of mass transfer is reduced; reducing the platinum oxide attached to the cathode surface by a shutdown strategy that stops the cathode side air supply; meanwhile, air is consumed, and oxidation reaction after shutdown is blocked; by judging the fixed point voltage, the number of times of pile activation is self-adaptive, so that the cost can be effectively saved and the activation effect can be improved. The activation strategy of the application can effectively shorten the activation time of the galvanic pile and save the hydrogen consumption; the self-adaption of different electric pile activation time and times can be realized, the cost can be effectively saved, and the effect of activating the fuel cell electric pile can be improved; meanwhile, the activation process comprises a start-stop strategy, so that the oxide on the cathode side can be effectively removed.
In one embodiment, the initial preset value is 0.1-0.6A/cm, the first current density value is 1.6-2.2A/cm, the second current density value is 1.0-1.6A/cm, the third current density value is 0.2-0.8A/cm, and the fourth current density value is 2.0-3.0A/cm.
In one embodiment, the predetermined voltage difference is selected to be 3-10 mV.
In one embodiment, the current preset time is 30-300 s.
In one embodiment, test conditions in the cycle are controlled prior to each activation cycle, including fuel cell temperature, gas pressure, and/or gas humidity. Test conditions in the activation process of the fuel cell can be set, for example, the temperature range of the fuel cell is controlled to be 75-85 ℃, the relative humidity range of the gas is controlled to be 60-90%, and the pressure control range of the gas is controlled to be 100-200 kPa.
Suitable values may be selected from a range of temperatures based on the material, drainage requirements, or power characteristics of the stack catalyst, for example, when the stack is at a higher power, the temperature may be selected to be a higher value, such as 85 ℃.
The method can screen proper values from the relative humidity range of gas according to the characteristics of materials, drainage requirements or power of a galvanic pile catalyst, 100% humidification is not recommended, under the condition of 100% humidification, the gas is easy to excessively humidify, liquid water can be generated in the internal reaction of the galvanic pile, the excessive humidification can cause the liquid water to gather on the surface of the catalyst, a gas transmission channel is blocked, external performance is attenuated, local undergassing is further caused, carbon corrosion is generated, and irreversible attenuation is caused to the galvanic pile. So that the relative humidity of the gas is 60% -90%.
Whether the galvanic pile is pressurized or not can be selected according to the drainage rate, and the purpose of pressurization and activation can strengthen the partial pressure of gas on one hand and promote the forward reaction; on the other hand, drainage of the pile can be enhanced.
Example 1
As shown in fig. 1 and 2, the stack activation method of the fuel cell includes the steps of:
step 1, starting a galvanic pile of the fuel cell, wherein the loading speed is 0.10A/(cm < s >), and loading current to enable the density to reach an initial preset value C0, wherein C0 is 0.2A/cm.
And 2, after the current is stabilized, the current stabilizing time is 120s. The current density is increased from the initial preset value to a first current density value C1. C1 is 1.8A/cm, and the loading rate is 0.20A/(cm. Times.s). Preferably, after the C1 value is reached, the current may be controlled to stabilize for a period of several seconds, for example 3s.
And 3, reducing the current density to a second current density value C2, wherein C2 is 1.2A/cm, the load shedding rate is 0.30A/(cm < s >), and the first current density value C1 is larger than the second current density value C2 and larger than an initial preset value C0. At this time, the number of times the current density reaches the peak first current density value C1 is 1, and the counter 1 counts the number of times the current density reaches the peak first current density value C1.
And 4, judging whether the number of times that the counter 1 has counted that the current density reaches the peak value first current density value C1 reaches the repetition number N1, wherein the preferable number of times of N1 is 2-4. When the data of the counter 1 is less than N1, step 2 is entered, and at the moment, the current density is increased from the second current density value to the first current density value, the load current density change rate is 0.10A/(cm x s) to 0.30A/(cm x s), then the load current density is reduced to the second current density value, and the load current density change rate is 0.20A/(cm x s) to 0.40A/(cm x s); when it is determined that the data of the counter 1 is not smaller than N1, the process proceeds to step 5.
And 5, loading the current density to a first current density value C1, wherein C1 is 1.8A/cm, and the loading rate is 0.20A/(cm < x s >).
And 6, reducing the current density to a third current density value C3, wherein C3 is 0.2A/cm, and the load shedding rate is 0.30A/(cm < s >). At this time, the number of times the current density reaches the third current density value C3 is 1, and the counter 2 counts the number of times the current density reaches the valley third current density value C3.
And 7, judging whether the count of the counter 2 for counting the times that the current density reaches the third current density value C3 of the valley value reaches the repetition times N2, wherein the optimal selection times of the N2 are 1-2 times. When the data of the counter 2 is less than N2, step 2 is entered, and at this time, the current density is increased from the second current density value to the first current density value, the load current density change rate is 0.10A/(cm x s) to 0.30A/(cm x s), then the load current density is decreased to the second current density value, and the load current density change rate is 0.20A/(cm x s) to 0.40A/(cm x s); when it is determined that the data of the counter 2 is not smaller than N2, the process proceeds to step 8. Repeating the steps 1-3 times to increase the current density from the third current density value to the first current density value, then reducing the current density to the second current density value, and repeating the steps 2-6. In fig. 1, the number of repetitions is two. In the step 2-7, the output power is reduced and increased rapidly, on one hand, the water and the temperature on the surface of the catalyst are retained at a reaction interface and cannot be converted in time along with the output power, and the reaction occurs at high temperature and high humidity, so that the reaction rate is increased, and the activation effect is more sufficient; on the other hand, the whole activation process time is shortened and the production efficiency is improved by a specific rapid load and unload mode, and the load and unload strategy is not equal to that of the normal load and then load is relieved and repeated for a plurality of times.
Step 8, increasing the current density from the third current density value C3 to a fourth current density value C4, wherein C4 is 2.0A/cm, and the loading rate is 0.20A/(cm×s). The current adopts large current output, so that on one hand, the voltage of the electric pile is reduced, the reduction reaction is enhanced, the oxide layer on the surface of the catalyst is reduced, and the effective reaction area is increased; on the other hand, the proton exchange membrane is wetted by a large amount of generated water, so that the proton conductivity of the proton exchange membrane is enhanced.
And 9, stabilizing the current density at a fourth current density value C4 within a current preset time T1, wherein C4 is 2.0A/cm, and recording the voltage value at the moment, wherein the voltage value is the fixed point voltage. The current preset time T1 is 30-300 s. The number of times the voltage value is recorded at this time is 1, and the counter 3 counts the number of times the voltage value is recorded.
Step 10, it is determined whether the number of times the statistical voltage value of the counter 3 is recorded is greater than 2. When judging that the current density is smaller than 2, reducing the current density from a fourth current density value C4 to a third current density value C3, then closing air supply, stopping the machine, and after stopping the machine for a plurality of seconds, entering a step 11, wherein the stopping time can be controlled within 5-30 seconds; c3 is 0.2A/cm, and the load shedding rate is 0.30A/(cm < s >). The air supply is closed, so that the oxidant is lost, the reaction process is lagged and still in the reaction process, the hydrogen is oxidized on the anode side to form ions to pass through the membrane, the ions are reduced to hydrogen again on the cathode side, the generated hydrogen reacts with the oxide layer on the surface of the electrode, the oxide on the surface is reduced, and the activity of the catalyst is improved. When the voltage is not less than 2, judging whether the difference between the voltage record data of two adjacent cycles is less than a preset voltage difference V1. If yes, the routine proceeds to step 14, where it is determined that activation is completed, and the activation flow is terminated. When no is determined, the same flow is adopted as when no is determined in step 10.
Step 11, restarting the galvanic pile, loading to the current density C0, wherein the loading speed is 0.10A/(cm < s >), and loading the current to enable the density to reach the initial preset value C0, wherein the C0 is 0.2A/cm.
Step 12, reassigning C1, C2 and C4 to be D1 of 2.2A/cm, D2 of 1.6A/cm and D4 of 0.6A/cm respectively;
step 13, repeating the steps 2-9 until the difference between the two adjacent voltage record data in the step 9 is smaller than V1 (preferably 3-10 mV);
and 14, stopping the machine, and completing activation.
The whole activation process can be controlled within 1h, each cycle takes about 15min, and three cycles take 45min in total. The whole activation process of the steps 1-14 can be controlled within 1h, so that the hydrogen consumption is greatly reduced.
As shown in fig. 3, the overall performance of the fuel cell stack after activation is obviously improved compared with that before activation, the average voltage drop after activation is far smaller than that before activation, the power after activation is also larger than that before activation, and the activated fuel cell stack can stably operate under high current and has good performance. As can be seen from fig. 3: on the one hand, under the same current density, the performance is obviously improved, when the current density is 2.2A/cm, the voltage is improved by about 51.5%, and the overall power is improved by 51.5%; on the other hand, the working interval is increased, the maximum current density of stable operation is only 2.2A/cm, the density of the activated electric density can be increased to more than 2.5A/cm, and the working interval is increased by more than 13.6%.
As shown in fig. 4, the performance of the fuel cell stack gradually increases as the number of activations increases. The performance of the activation method is close to the optimal performance of a galvanic pile after about three times of activation. It should be noted that the time and cost required for the galvanic pile activation increase with the number of activation times, so here, three activation rounds are taken as an example, and the activation method in the present application includes, but is not limited to, three activation rounds.
In one embodiment, as shown in fig. 5, to enhance the reaction of hydrogen with the oxide layer on the electrode surface, the air supply on the cathode side may be turned off in step seven, a small current for several seconds may be applied, and then shutdown may be performed. The preferred range of the current density of the small current is 0.02-0.1A/cm. As shown in FIG. 5, the current density of the small current was 0.05A/cm. Preferably, the duration of several seconds does not exceed 30s.
Comparative example 1
The comparative example 1 activated stack and example 1 activated stack were of the same type and had substantially the same basic performance parameters. This comparative example 1 uses an activation mode of fixed activation current density step loading:
controlling the temperature of the galvanic pile at 80 ℃, the gas pressure at 100kPa and the humidity at 95%;
the step loading fixed activation current density is 0.1A/cm, 0.5A/cm, 1.0A/cm, 1.5A/cm, and the rest is 3min under different activation current densities; and then rapidly reducing load, and stopping the discharge process normally.
Repeating the steps to complete the multi-round activation method.
In comparison with the activation pattern in comparative example 1, the activation effect in this scheme is shown in the following table:
as can be seen from the above table, compared with comparative example 1, the inventive example 1 not only improves the activation efficiency, but also saves time; on the other hand, excessive load pulling is prevented, the power exceeding the current performance is forced to be output by the electric pile, and the damage of the electric pile is avoided. Meanwhile, in the process of gradually improving the activation current density, the embodiment 1 of the application continuously approaches the optimal performance of the galvanic pile, thereby improving the activation performance of the galvanic pile.
The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present application should be included in the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.
Claims (7)
1. A stack activation method of fuel cell is characterized by comprising a plurality of activation cycles, wherein when the difference between the voltage record data of two adjacent cycles is smaller than the preset voltage difference value, the completion of activation is judged,
each activation cycle comprises the steps of:
step one, starting a galvanic pile of a fuel cell, loading current to enable the density of the galvanic pile to reach an initial preset value, and loading the change rate of the current to be 0.05A/(cm < s >) to be 0.15A/(cm < s >);
after the current is stabilized, the current density is increased from the initial preset value to a first current density value, the load current density change rate is 0.10A/(cm & lts & gt) to 0.30A/(cm & lts & gt), then the load current density is reduced to a second current density value, the load reduction current density change rate is 0.20A/(cm & lts & gt to 0.40A/(cm & lts & gt), and the first current density value is more than the second current density value is more than the initial preset value;
step three, the current density is increased from the second current density value to the first current density value, the load current density change rate is 0.10A/(cm, s) to 0.30A/(cm, s), then the load current density is reduced to the second current density value, the load reduction current density change rate is 0.20A/(cm, s) to 0.40A/(cm, s), and the repetition number of the second current density loaded to the first current density value and then reduced to the second current density is 2 to 4.
Step four, increasing the current density from the second current density value to the first current density value, wherein the load current density change rate is 0.10A/(cm & lts & gt) to 0.30A/(cm & lts & gt), and then reducing the load current density from the first current density value to a third current density value, and the load shedding current density change rate is 0.20A/(cm & lts & gt) to 0.40A/(cm & lts & gt).
Repeating the following steps for 1-3 times: increasing the current density from the third current density value to the first current density value, then decreasing the current density to the second current density value, and repeating the processes from the third step to the fourth step;
step six, after the current density is increased from the third current density value to the fourth current density value, the load current density change rate is 0.10A/(cm < n >. S) to 0.30A/(cm < n >) and the current is stabilized for a preset time, and the voltage value at the moment is recorded;
step seven, the current density is reduced from the fourth current density value to the third current density value, then the air supply on the cathode side is closed, the shutdown is carried out,
the first current density value, the second current density value and the fourth current density value are all larger than the value of the last activation cycle once.
2. The method according to claim 1, wherein the test conditions in the cycle are controlled before each activation cycle, the test conditions including a fuel cell temperature, a gas pressure and/or a gas humidity, the fuel cell temperature is in the range of 75 to 85 ℃, the gas relative humidity is in the range of 60 to 90%, and the gas pressure is controlled in the range of 100 to 200kpa.
3. The method according to claim 1, wherein the initial preset value is 0.1-0.6 a/cm, the first current density value is 1.6-2.2 a/cm, the second current density value is 1.0-1.6 a/cm, the third current density value is 0.2-0.8 a/cm, and the fourth current density value is 2.0-3.0 a/cm.
4. The method of activating a galvanic pile according to claim 1, wherein the air supply to the cathode side is turned off, a small current is additionally applied for several seconds, the current density of the small current is preferably in the range of 0.02 to 0.1a/cm for several seconds not more than 30 seconds, and then shutdown is performed.
5. The method of claim 1, wherein the predetermined voltage difference is 3-10 mv.
6. The method of claim 1, wherein the current preset time is 30-300 s.
7. The method according to claim 1, wherein in the second step, after the current is stabilized, the current is stabilized for a period of several seconds, and the stabilizing period ranges from 30s to 500s.
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| CN117766810A (en) * | 2024-02-22 | 2024-03-26 | 上海氢晨新能源科技有限公司 | activation method of fuel cell, electronic equipment and electric equipment |
| CN117766810B (en) * | 2024-02-22 | 2024-04-23 | 上海氢晨新能源科技有限公司 | Activation method of fuel cell, electronic equipment and electric equipment |
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