Method for starting galvanic pile at low temperature and galvanic pile system
By detecting and responding to the internal temperature and voltage of the stack in real time, hydrogen is introduced into the stack and purged, which accelerates the low-temperature startup speed, solving the problem of difficulty in starting the fuel cell system in a low-temperature environment, and achieving more efficient stack heating and hydrogen utilization.
Patent Information
- Application Number
- CN202510404248.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-01
- Publication Date
- 2025-07-01
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The difficulty in starting fuel cell systems in low-temperature environments has led to limited application promotion in low-temperature areas in the north.
By detecting the internal temperature and voltage of the stack in real time, hydrogen is sent to the anode and cathode of the stack in response to low temperature conditions, and the purge unit is turned on to react to the hydrogen with air; when the temperature reaches the preset value, the discharge step and hydrogen supply strategy are adjusted, and the recovered exhaust heat is used for heating.
The low-temperature starting speed of the stack is accelerated, the cathode potential and open circuit voltage are reduced, the high potential damage to the stack is avoided, the hydrogen utilization rate is improved, and the energy efficiency of the system is improved.
Smart Images
Figure CN120237238A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the technical field of fuel cells, and more particularly, to a method for low-temperature startup of a stack and a stack system. Background Art
[0002] As a clean energy source, fuel cells have received increasing attention in recent years. In particular, the environmental adaptability research of fuel cells, and the low-temperature environmental adaptability of hydrogen fuel cell systems is an extremely important factor, which determines whether they can be applied and promoted in northern low-temperature regions. Therefore, low-temperature startup is a technical problem that must be overcome in the development process of fuel cell systems. Summary of the Invention
[0003] The purpose of the present disclosure is to provide a method for low-temperature startup of a stack and a stack system for the technical problems in the related art. The specific solutions are as follows:
[0004] A first aspect of an embodiment of the present disclosure provides a method for low-temperature startup of a stack, including: detecting the internal temperature and voltage of the stack in real time; in response to the stack temperature being lower than a first preset temperature, introducing hydrogen into the anode and cathode of the stack, and at the same time turning on a purge unit to react hydrogen with the air in the stack; in response to the stack temperature reaching a second preset temperature, stopping supplying hydrogen to the cathode of the stack; before stopping supplying hydrogen to the cathode of the stack, running a first preset discharge step to load the current density of the stack to a first current density; in response to the stack temperature reaching a third preset temperature, running a second preset discharge step to load the current density of the stack to a second current density; in response to the stack temperature reaching a fourth preset temperature, recovering the heat of the stack exhaust gas to heat the stack.
[0005] In some embodiments, in response to the stack temperature reaching the first preset temperature, turning on an electric heater to raise the temperature of the stack.
[0006] In some embodiments, in response to the current density of the stack reaching a fourth current density, turning off the electric heater.
[0007] In some embodiments, based on the stack temperature reaching the second preset temperature, if the current voltage value is lower than a first preset voltage, the load current is reduced within a preset waiting time to unload the actual current density to the first current density.
[0008] In some embodiments, based on the stack temperature reaching the third preset temperature, if the current voltage value is lower than a second preset voltage, the load current is reduced within the preset waiting time to unload the actual current density to the second current density.
[0009] In some embodiments, the first preset temperature is -5°C; and / or the second preset temperature is 0°C; and / or; the third preset temperature is 15°C; and / or the fourth preset temperature is 30°C.
[0010] In some embodiments, the first current density is 0.1 - 0.2 A / cm 2 ; and / or the second current density is 0.4 A / cm 2 -0.5 A / cm 2 .
[0011] In some embodiments, the first minimum voltage value is 0.3 V; and / or the second minimum voltage value is 0.5 V; and / or the third minimum voltage value is 0.6 V.
[0012] In some embodiments, the preset waiting time is 30 seconds.
[0013] A first aspect of the embodiments of the present disclosure provides a stack system, which executes the method for low-temperature startup of the stack provided in the first aspect of the embodiments of the present disclosure, including: a stack, provided with an electric heater, configured to accelerate the low-temperature startup of the stack; a recovery tank, communicated with the stack, configured to recover unreacted hydrogen in the stack; a purge unit, used to purge the cathode and anode of the stack.
[0014] The above solution of the embodiments of the present disclosure has at least the following beneficial effects compared with the related art:
[0015] By heating the stack through multiple channels, the low-temperature startup speed of the stack is accelerated; the heat generation during the purge process is increased, the cathode potential is reduced, the open-circuit voltage of the stack is reduced, and the damage to the stack caused by high potential is avoided; by using the recovered hydrogen for purging, the utilization rate of hydrogen can also be improved, and the energy efficiency of the system can be enhanced.
[0016] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the following drawings in the description are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts. In the drawings:
[0018] Figure 1 A schematic structural diagram of a stack system shown according to an exemplary embodiment.
[0019] Figure 2Flowchart of a method for low-temperature startup of an electric stack shown according to an exemplary embodiment.
[0020] Figure 3 Flowchart of the temperature-rising stage of a method for low-temperature startup of an electric stack shown according to an exemplary embodiment
[0021] Reference numerals:
[0022] Electric stack 100, temperature detection module 101, voltage detection module 102, electric heater 110, lithium battery 120;
[0023] Hydrogen storage tank 200, heat exchanger 300, heat exchange control valve 310, recovery tank 400, purge unit 500. Detailed implementation manners
[0024] In order to make the objectives, technical solutions and advantages of the present disclosure clearer, the present disclosure will be further described in detail below with reference to the accompanying drawings. Apparently, the described embodiments are only a part rather than all of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.
[0025] The terms used in the embodiments of the present disclosure are only for the purpose of describing specific embodiments, and are not intended to limit the present disclosure. The singular forms "a", "the" and "said" used in the embodiments of the present disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. "Plural" generally includes at least two, and other quantifiers are similar.
[0026] It should be understood that although the terms first, second, third, etc. may be used in the embodiments of the present disclosure to describe, these descriptions should not be limited to these terms. These terms are only used to distinguish the described objects. For example, without departing from the scope of the embodiments of the present disclosure, the first may also be referred to as the second, and similarly, the second may also be referred to as the first. In addition, the terms "first", "second", "third", etc. are only for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0027] It should be understood that the term " / and / " used herein is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after. The singular forms "a", "the" and "said" are also intended to include the plural forms unless the context clearly indicates otherwise.
[0028] It can be further understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "front", "rear", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this embodiment and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present invention.
[0029] In the description of the present disclosure, it should be noted that, unless otherwise clearly specified and defined, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0030] Depending on the context, the words "if" and "when" as used herein may be interpreted as "when" or "while" or "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrases "if determined" or "if detecting (stated condition or event)" may be interpreted as "when determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)".
[0031] It should also be noted that the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, such that a commodity or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such commodity or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the presence of additional identical elements in the commodity or device comprising said element.
[0032] In the related art of this field, a single channel is often used for stack heating, and during the low-temperature start-up purge or electric heating stage, the fuel cell stack will be in an open-circuit voltage state, and irreversible damage will be caused to the stack under such high-potential conditions.
[0033] The object of the present invention is to overcome the deficiencies of the prior art and provide a method and a stack system for low-temperature start-up of a stack, including: detecting the internal temperature and voltage of the stack in real time; in response to the stack temperature being lower than a first preset temperature, introducing hydrogen into the anode and cathode of the stack, and at the same time turning on a purge unit to make hydrogen react with the air in the stack; in response to the stack temperature reaching a second preset temperature, stopping supplying hydrogen to the cathode of the stack; before stopping supplying hydrogen to the cathode of the stack, running a first preset discharge step to load the current density of the stack to a first current density; in response to the stack temperature reaching a third preset temperature, running a second preset discharge step to load the current density of the stack to a second current density; in response to the stack temperature reaching a fourth preset temperature, recovering the heat of the stack exhaust gas to heat the stack.
[0034] The method for low-temperature start-up of the stack provided by the present disclosure heats the stack through multiple channels, accelerating the low-temperature start-up speed of the stack; increasing the heat generation during the purge process, reducing the cathode potential, reducing the open-circuit voltage of the stack, and avoiding damage to the stack caused by high potential; using recycled hydrogen for purging can also improve the utilization rate of hydrogen and enhance the energy efficiency of the system.
[0035] The optional embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.
[0036] A method and a stack system 1000 for low-temperature start-up of a stack 100 provided by the present invention are as Figure 1 shown. The stack system 1000 includes a stack 100 and its test control system. The test control system includes a temperature detection module 101 and a voltage detection module 102 disposed inside the stack 100, which are used to detect the real-time temperature and voltage inside the stack 100 to accurately control the stages during the low-temperature start-up of the stack 100 and keep the internal state of the stack 100 relatively stable.
[0037] In some embodiments, the test control system further includes an electric heating module. The electric heating module includes an electric heater 110 and a lithium battery 120. At least a part of the electric heater 110 is disposed inside the stack 100. The input end of the lithium battery 120 is connected to the stack 100, and the output end of the lithium battery 120 is connected to the electric heater 110. In response to the lithium battery 120 supplying power to the electric heater 110, the temperature of the electric heater 110 rises to increase the internal temperature of the stack 100, shortening the low-temperature start-up time of the stack 100.
[0038] In some embodiments, the fuel cell stack 100 has a first intake port and a first exhaust port. The first intake port is used to deliver hydrogen into the fuel cell stack 100, and the first exhaust port is used to discharge the waste gas generated by the fuel cell stack 100 from the fuel cell stack 100. The fuel cell system 1000 further includes a hydrogen storage tank, which is connected to the first intake port of the fuel cell stack 100. That is, the hydrogen storage tank supplies hydrogen to the fuel cell stack 100 through the first intake port.
[0039] In some embodiments, a heat exchanger 300 is provided between the hydrogen storage tank and the first intake port, which is used to control the temperature of the hydrogen supplied from the hydrogen storage tank into the fuel cell stack 100. During the process of the hydrogen storage tank supplying hydrogen to the fuel cell stack 100, in response to the heat exchanger 300 being in an open state, the temperature of the hydrogen supplied from the hydrogen storage tank to the fuel cell stack 100 increases, which can accelerate the reaction rate inside the fuel cell stack 100 and rapidly increase the temperature inside the fuel cell stack 100.
[0040] In some embodiments, the fuel cell system 1000 further includes a heat exchange control valve 310. The heat exchange control valve 310 can be a three-way component, which is respectively connected to the first exhaust port, the heat exchanger 300, and the outside of the fuel cell system 1000. In response to the waste gas inside the fuel cell stack 100 being discharged from the first exhaust port, the heat exchange control valve 310 can be adjusted to control the waste gas to be delivered to the heat exchanger 300, or the outside of the fuel cell system 1000, or both the heat exchanger 300 and the outside of the fuel cell system 1000. The heat exchange control valve 310 is a one-way control valve, that is, the fluid passing through the heat exchange control valve 310 can only flow from the first exhaust port towards the heat exchanger 300 and the outside of the fuel cell system 1000.
[0041] In some embodiments, the fuel cell stack 100 has a second intake port and a second exhaust port. The fuel cell system 1000 further includes a recovery tank 400, which is respectively connected to the second intake port and the second exhaust port of the fuel cell stack 100, and is configured to recover the unreacted hydrogen in the fuel cell stack 100. The temperature of the hydrogen collected in the recovery tank 400 is significantly higher than the temperature of the hydrogen in the hydrogen storage tank. Therefore, when using the hydrogen in the recovery tank 400 to supply fuel to the fuel cell stack 100, it can also provide a certain amount of heat energy for the fuel cell stack 100, improving the hydrogen utilization rate while accelerating the low-temperature startup of the fuel cell stack 100.
[0042] In some embodiments, the stack system 1000 further includes a purging unit 500 configured to purge the cathode, or the anode, or both the cathode and the anode of the stack 100. By means of the purging unit 500, a small amount of hydrogen can be maintained in the anode of the stack 100 to increase the heat generation during the purging process, reduce the cathode potential of the stack 100, lower the open-circuit voltage of the stack 100, and avoid damage to the stack 100 caused by high potential. If the recycled hydrogen in the recovery tank 400 is used for purging, the utilization rate of hydrogen can be further improved and the energy efficiency of the system can be enhanced.
[0043] Specifically, when the stack 100 is operating normally, the hydrogen in the anode undergoes an oxidation reaction, releasing electrons and protons. The electrons flow through the external circuit to the cathode, and the protons reach the cathode through the proton exchange membrane and react with oxygen to undergo a reduction reaction. When purging is carried out, if there is no hydrogen in the anode, other reactions (such as carbon corrosion and water electrolysis) may occur in the anode to generate protons and electrons to maintain charge balance. The potentials of these reactions are relatively high, which will increase the anode potential, and correspondingly, the cathode potential will also increase. However, when there is hydrogen in the anode, the hydrogen oxidation reaction proceeds normally, providing a low-potential electron source, keeping the anode potential at a relatively low level, thereby maintaining the potential balance of the entire stack 100, reducing the cathode potential, and maintaining the charge balance inside the stack 100.
[0044] The stack system 1000 provided by the present disclosure is applicable to the low-temperature startup method of the stack 100 provided by the present disclosure, such as Figure 2 The low-temperature startup method of the stack 100 shown includes the following steps:
[0045] S100. Real-time detect the internal temperature and voltage of the stack 100.
[0046] The stack 100 in this embodiment is a stack 100 composed of fuel cells, and the entire startup process of the stack 100 is assisted by the test control system. Therefore, in this step, it is necessary to detect the temperature and voltage at each stage of the startup of the stack 100 through the test control system.
[0047] S200. In response to the temperature of the stack 100 being lower than a first preset temperature, introduce hydrogen into the anode and cathode of the stack 100, and at the same time, turn on the purging unit 500 to cause the hydrogen to react with the air in the stack 100;
[0048] The method provided by the present disclosure is applied to the startup of the stack 100 in a low-temperature environment. Therefore, this method is only enabled when the temperature of the stack 100 is lower than the first preset temperature. When the temperature of the stack 100 is lower than the first preset temperature, the test control system controls the hydrogen storage bottle to introduce hydrogen into the anode and cathode of the stack 100, and at the same time, turns on the purging unit 500 to cause the hydrogen to react with the air in the stack 100.
[0049] During the low-temperature start-up purging stage, the hydrogen fuel cell stack 100 will be in an open-circuit voltage state. Under such high-potential conditions, irreversible damage will be caused to the stack 100. In the present disclosure, by introducing a small amount of hydrogen into the cathode during this stage, the heat generation during the purging process can be increased; the cathode potential of the stack 100 can be reduced, the open-circuit voltage of the stack 100 can be reduced, and damage to the stack 100 caused by high potential can be avoided. Its working principle has been described in the foregoing text and will not be elaborated here. When purging the cathode and anode of the stack 100, it is necessary to control characteristics such as the gas flow rate, temperature, and purging duration through a test control system to ensure the purging effect.
[0050] In some embodiments, the first preset temperature is -5°C. Different types of stacks 100 have different temperature requirements for low-temperature start-up. Generally speaking, most stacks 100 can be started in an environment of -20°C to -30°C. For example, some proton exchange membrane fuel cell stacks 100 are usually designed to have a low-temperature start-up temperature of about -20°C. In the present method, the first preset temperature is set to -5°C, that is, regardless of the type of stack 100 applied, as long as the temperature of the stack 100 is lower than -5°C, this method can be used for rapid start-up of the stack 100 at low temperature.
[0051] In some embodiments, in the step of introducing hydrogen into the anode and cathode of the stack 100, the oxygen introduced into the stack 100 can be sourced from a hydrogen storage tank or a recovery tank 400. If the recycled hydrogen is used for purging, the utilization rate of hydrogen can be further improved and the system energy efficiency can be enhanced.
[0052] In some embodiments, in response to the temperature of the stack 100 reaching the first preset temperature, the electric heater 110 is turned on to raise the temperature of the stack 100.
[0053] For the stack system 1000 containing liquid water, the electric heater 110 can prevent water from freezing at low temperatures. Since the volume of water expands after freezing, it may damage the internal structure of the stack 100, such as causing the membrane electrode to rupture or the flow channel to be blocked. The electric heater 110 maintains the temperature above the freezing point, effectively avoiding such a situation.
[0054] During the operation of the stack 100, the electric heater 110 can finely adjust the temperature according to the actual situation, compensate for the heat loss of the stack 100, and keep the temperature of the stack 100 within a stable range, avoiding adverse effects on the performance and lifespan of the stack 100 due to temperature fluctuations.
[0055] S201. Before stopping the hydrogen supply to the cathode of the stack 100, perform a first preset discharging step to load the current density of the stack 100 to a first current density.
[0056] In some embodiments, a first preset voltage is set in step S201, and the first preset voltage is the minimum voltage of this step. In response to the temperature of the battery stack 100 reaching the second preset temperature, the test control system detects the internal voltage of the battery stack 100. If the current voltage value is lower than the first preset voltage, the loading current is reduced within the preset waiting time to unload the actual current density to the first current density. The first preset voltage is 0.3-0.35V. The first current density is 0.1A / cm 2 -0.2A / cm 2 .
[0057] S300. In response to the temperature of the fuel cell stack 100 reaching a second preset temperature, stop supplying hydrogen to the cathode of the fuel cell stack 100.
[0058] In some embodiments, the second preset temperature is 0°C. Because the head and tail of the stack 100 are easier to dissipate heat, in a low temperature environment, water is more likely to condense or even freeze at the head and tail, blocking the pores of the gas diffusion layer and the channels of the bipolar plate. The ice inside the stack 100 can be melted through the above steps. At this time, the ice layer attached to the inner wall of the stack 100 has been removed. If hydrogen continues to be introduced, not only will the hydrogen be unable to be effectively utilized, but it may also cause damage or poisoning of the electrode material, destroy the chemical balance inside the fuel cell, and cause the stack 100 to fail to work normally, reducing the performance and life of the stack 100. Therefore, it is necessary to stop supplying hydrogen to the cathode of the stack 100.
[0059] S400. In response to the temperature of the fuel cell stack 100 reaching a third preset temperature, executing a second preset discharge step to load the current density of the fuel cell stack 100 to a second current density.
[0060] In some embodiments, a second preset voltage is set in step S400, and the second preset voltage is the minimum voltage of this step. In response to the temperature of the fuel cell stack 100 reaching a third preset temperature, the test control system detects the internal voltage of the fuel cell stack 100. If the current voltage value is lower than the second preset voltage, the loading current is reduced within the preset waiting time to unload the actual current density to the second current density.
[0061] In some embodiments, the third preset temperature is 15°C; the second current density is 0.4A / cm 2 -0.5A / cm 2 ; The second preset voltage is 0.5-0.6V.
[0062] S401 . In response to the temperature of the fuel cell stack 100 reaching a fourth preset temperature, recover the heat of the exhaust gas of the fuel cell stack 100 to heat the fuel cell stack 100 .
[0063] In some embodiments, the fourth preset temperature is 30 °C. In response to the temperature of the fuel cell stack 100 reaching 30 °C, the heat exchange control valve 310 is opened, so that the exhaust gas of the fuel cell stack 100 flows through the heat exchanger 300 via the first exhaust port of the fuel cell stack 100 and re-enters the interior of the fuel cell stack 100. In this step, a third preset voltage is set, and the third preset voltage is the lowest voltage in this step. In response to the temperature of the fuel cell stack 100 reaching the fourth preset temperature, the test control system detects the voltage inside the fuel cell stack 100. If the current voltage value is greater than or equal to the third preset voltage, the fuel cell stack 100 normally loads current; if the current voltage value is lower than the third preset voltage, the load current is reduced within a preset waiting time to unload the actual current density to the second current density. The third preset voltage is 0.6 V.
[0064] In some embodiments, the preset waiting time is 30 seconds.
[0065] In some embodiments, in response to the current density of the fuel cell stack 100 reaching the fourth current density, the fuel cell stack 100 can be normally started and operated, and at this time, the electric heater 110 can be turned off.
[0066] The fuel cell stack system 1000 provided by the present disclosure can first purge the cathode and anode of the fuel cell stack 100 simultaneously; and in different stages of the low-temperature start of the fuel cell stack 100, various methods such as recycling hydrogen, the electric heater 110, and the heat exchanger 300 are respectively used to heat the fuel cell stack 100, accelerate the low-temperature start speed of the fuel cell stack 100, increase the heat generation during the purging process, reduce the cathode potential, reduce the open-circuit voltage of the fuel cell stack 100, and avoid damage to the fuel cell stack 100 caused by high potential; using recycled hydrogen for purging can also improve the utilization rate of hydrogen and enhance the energy efficiency of the system.
[0067] For the method for low-temperature start of the fuel cell stack 100 and the specific structure, working principle, and beneficial effects of the fuel cell stack system 1000 provided by the embodiments of the present disclosure, reference can be made to the method for low-temperature start of the fuel cell stack 100 and the fuel cell stack system 1000 described in any of the above embodiments, and details are not described herein again.
[0068] Finally, it should be noted that the embodiments in this specification are described in a progressive manner, and the key points of each embodiment are the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the system or device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.
[0069] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit it; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the present disclosure in each embodiment.
Claims
1. A method for low temperature startup of a fuel cell stack, characterized in that: include: Real-time detection of internal temperature and voltage of the battery stack; In response to the temperature of the fuel cell stack being lower than a first preset temperature, hydrogen is introduced into the anode and cathode of the fuel cell stack, and a purge unit is simultaneously started to allow the hydrogen to react with air in the fuel cell stack; In response to the temperature of the fuel cell stack reaching a second preset temperature, stopping supplying hydrogen to the cathode of the fuel cell stack; Before stopping supplying hydrogen to the cathode of the stack, running a first preset discharge step to load the current density of the stack to a first current density; In response to the temperature of the battery stack reaching a third preset temperature, executing a second preset discharge step to load the current density of the battery stack to a second current density; In response to the temperature of the fuel cell stack reaching a fourth preset temperature, heat from the fuel cell stack exhaust is recovered to heat the fuel cell stack.
2. The method for low temperature startup of a fuel cell stack according to claim 1, characterized in that: In response to the temperature of the fuel cell stack reaching a first preset temperature, the electric heater is turned on to increase the temperature of the fuel cell stack.
3. The method for low temperature startup of a fuel cell stack according to claim 2, characterized in that: In response to the current density of the fuel cell stack reaching a fourth current density, the electric heater is turned off.
4. The method for low temperature startup of a fuel cell stack according to claim 1, characterized in that: Based on the temperature of the battery stack reaching the second preset temperature, if the current voltage value is lower than the first preset voltage, the loading current is reduced within the preset waiting time to unload the actual current density to the first current density.
5. The method for low temperature startup of a fuel cell stack according to claim 1, characterized in that: Based on the temperature of the battery stack reaching the third preset temperature, if the current voltage value is lower than the second preset voltage, the loading current is reduced within the preset waiting time to unload the actual current density to the second current density.
6. The method for low temperature startup of a fuel cell stack according to claim 1, characterized in that: The first preset temperature is -5°C; and / or The second preset temperature is 0°C; and / or The third preset temperature is 15°C; and / or The fourth preset temperature is 30°C.
7. The method for low temperature startup of a fuel cell stack according to claim 1, characterized in that: The first current density is 0.1-0.2A / cm 2 ; and / or The second current density is 0.4A / cm 2 -0.5A / cm 2 .
8. The method for low temperature startup of a fuel cell stack according to claim 1, characterized in that: The first minimum voltage value is 0.3V; and / or The second minimum voltage value is 0.5V; and / or The third lowest voltage value is 0.6V.
9. The method for low temperature startup of a fuel cell stack according to claim 4 or 5, characterized in that: The preset waiting time is 30 seconds.
10. A battery stack system, characterized in that: The method for executing low temperature startup of a fuel cell stack according to any one of claims 1 to 9 comprises: The stack is provided with an electric heater configured to accelerate the low-temperature start-up of the stack; A recovery tank, in communication with the fuel cell stack, configured to recover incompletely reacted hydrogen in the fuel cell stack; A purge unit is used to purge the cathode and anode of the fuel cell stack.