Early fault identification method for immersed liquid cooling energy storage system

Abstract

The invention discloses an early fault identification method for an immersed liquid-cooled energy storage system. The method comprises the following steps: step 1, taking a certain volume of cooling liquid from a sampling port of the immersed liquid-cooled energy storage system and storing the cooling liquid in an injector; 2, a certain volume of argon is injected into an injector, and constant-temperature oscillation is carried out to enable cooling liquid-gas two phases to reach gas-liquid balance; 3, detecting the content of each thermal runaway characteristic gas in the gas; and 4, recognizing early thermal runaway faults of the energy storage battery and the system according to the characteristic gas. According to the method, the dissolved gas component in the cooling liquid of the immersed liquid-cooled energy storage system is used for carrying out early fault identification on the energy storage battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of immersion liquid-cooled energy storage, and in particular relates to an early fault identification method for an immersion liquid-cooled energy storage system. Background Art

[0002] With the continuous improvement of the energy consumption structure, the energy storage battery industry has shown explosive development, and the safety and stability of energy storage systems have attracted more and more attention. In the field of battery cooling technology, immersion liquid cooling has emerged. This method immerses the energy storage battery in a special insulating coolant (with high thermal conductivity and specific heat capacity), which can more effectively absorb and conduct heat faster, improving the heat dissipation efficiency of the system. Compared with traditional air-cooled heat dissipation and liquid cold plate heat dissipation technology, immersion liquid cooling technology can make the temperature field in the battery pack more uniform, ensuring that the battery operates within the optimal temperature range, thereby extending the battery system service life, while avoiding local high temperature and improving the safety performance of the energy storage system.

[0003] Different from the current air-cooled and liquid-cooled energy storage systems, which have cluster-level or package-level fire gas sensor arrangements and trigger fire warnings when combustible gas or thermal runaway is detected, the submerged liquid cooling system uses a sealed liquid-filled structure, and only sets a fire detector on the top of the battery compartment as a fire warning signal, and only detects carbon monoxide, hydrogen, smoke, VOC, temperature and other information. There is a problem that it cannot identify and warn when there is an early fault in the battery, and it is impossible to intervene as early as possible. Therefore, an early fault identification method for an submerged liquid-cooled energy storage system is provided to solve the problem that the existing submerged liquid-cooled energy storage system cannot intervene in thermal runaway as early as possible. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for early fault identification of an immersion liquid-cooled energy storage system.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions, including.

[0008] Take a certain volume of coolant from the sampling port of the immersion liquid-cooled energy storage system and store it in a syringe;

[0009] Inject a certain volume of argon into the syringe, oscillate at a constant temperature to make the coolant-gas two phases reach gas-liquid equilibrium, and remove the characteristic gas dissolved in the coolant;

[0010] Detect the content of thermal runaway characteristic gases in the gas;

[0011] Identify early thermal runaway failures of energy storage batteries and systems based on characteristic gases.

[0012] As a preferred solution of the method for early fault identification of the submerged liquid-cooled energy storage system of the present invention, the volume ratio of the coolant to the argon gas is 3 to 5:1.

[0013] As a preferred solution of the method for early fault identification of the submerged liquid-cooled energy storage system described in the present invention, the thermal runaway characteristic gases include hydrogen, carbon monoxide, carbon dioxide, ethylene, butane, and fluoromethane.

[0014] As a preferred scheme of the early fault identification method of the immersion liquid-cooled energy storage system described in the present invention, the constant temperature oscillation, wherein the oscillation frequency is 250 to 300 times / minute, the oscillation amplitude is 30 to 40 mm, the temperature is 35 to 50°C, and the total oscillation time is 20 to 50 minutes.

[0015] As a preferred solution of the method for early fault identification of the submerged liquid-cooled energy storage system of the present invention, the constant temperature oscillation is continuous oscillation for 10 to 50 minutes and rest for 5 to 15 minutes.

[0016] As a preferred solution of the method for early fault identification of the submerged liquid-cooled energy storage system of the present invention, the content of the thermal runaway characteristic gas is measured by gas chromatography.

[0017] As a preferred scheme of the method for early fault identification of the submerged liquid-cooled energy storage system described in the present invention, the chromatographic column of the gas chromatography is selected from a silica gel column, a mixed stationary phase PorapkT column, a PLOT Q capillary column or other chromatographic columns that can separate gases such as hydrogen, carbon monoxide, carbon dioxide, ethylene, butane, and fluoromethane.

[0018] As a preferred scheme of the early fault identification method of the immersion liquid-cooled energy storage system described in the present invention, the detector of the gas chromatography is selected from TCD, FID, MS or other detectors that respond to gases such as hydrogen, carbon monoxide, carbon dioxide, ethylene, butane, and fluoromethane.

[0019] As a preferred solution of the method for early fault identification of the submerged liquid-cooled energy storage system of the present invention, wherein: the thermal runaway fault is identified by the type of characteristic gas;

[0020] When the characteristic gas is ethylene or carbon dioxide, the fault type is the decomposition reaction of the solid electrolyte interface (SEI) film;

[0021] When the characteristic gas is ethylene or propane, the fault type is a reaction between the negative electrode and the electrolyte;

[0022] When the characteristic gas is hydrogen, the fault type is the reaction between the negative electrode and the binder PVDF or the early overcharge or overdischarge of the battery;

[0023] When the characteristic gas is carbon dioxide or carbon monoxide, the fault type is a reaction between the positive electrode and the electrolyte;

[0024] When the characteristic gas is fluoromethane, the fault type is decomposition reaction of the electrolyte.

[0025] As a preferred scheme of the early fault identification method of the immersion liquid-cooled energy storage system described in the present invention, when the characteristic gas is ethylene, the composition of the electrolyte reacting with the negative electrode is ethylene carbonate (EC) + diethyl carbonate (DEC); when the characteristic gas is propane, the composition of the electrolyte reacting with the negative electrode is EC + dimethyl carbonate (DMC).

[0026] Beneficial effects of the present invention:

[0027] The present invention provides an early fault identification method for an immersion liquid-cooled energy storage system, which identifies early thermal runaway faults of energy storage batteries and systems by detecting specific gas components dissolved in the coolant and their content. This method realizes early identification of thermal runaway faults of immersion liquid-cooled systems, can detect potential faults earlier, and thus take preventive measures before the fault occurs, thereby improving the safety and reliability of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0029] Figure 1 Schematic diagram of the preparation of an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0033] The raw materials used in the present invention are all commercially available unless otherwise specified.

[0034] The gas chromatograph model used in the present invention is Agilent 7890.

[0035] Example 1

[0036] Reference Figure 1 The coolant detected in this embodiment is taken from the immersion liquid-cooled battery fault simulation system. A 280Ah lithium iron phosphate battery is overcharged to 5V at a constant voltage, with a cut-off current of 0.2mA. After the battery surface temperature rises, 40ml of coolant is taken, 10ml of argon is injected, and the mixture is shaken at 40°C for 10min, and then left to stand for 10min. This cycle of constant temperature shaking is repeated for 30min to allow the coolant-gas phase to reach gas-liquid equilibrium. A gas chromatograph is then used, with the detector configured as TCD+FID and the chromatographic column using a molecular sieve column + silica gel column to detect the dissolved gas components. The results are shown in the following table.

[0037] Table 1

[0038]

[0039] Example 2

[0040] The coolant detected in this embodiment was taken from an immersion liquid-cooled battery fault simulation system. A 280Ah lithium iron phosphate battery (the electrolyte adopts a mixed solvent of EC+DEC) was heated to thermal runaway with a heating power of 100W. After detecting that the battery surface temperature has risen, 40ml of coolant was taken, 10ml of argon gas was injected, and the mixture was shaken at 35°C for 10min and left to stand for 10min. This cycle of constant temperature shaking was repeated for 30min to allow the coolant-gas phase to reach gas-liquid equilibrium. A gas chromatograph was used with an MS detector configuration and a PorapkT column as the chromatographic column to detect the dissolved gas components. The results are shown in the following table.

[0041] Table 2

[0042]

[0043] Example 3

[0044] The coolant detected in this embodiment was taken from an immersion liquid-cooled battery fault simulation system. A 280Ah lithium iron phosphate battery (the electrolyte adopts a mixed solvent of EC+DMC) was heated to thermal runaway with a heating power of 100W. After the battery surface temperature was detected to have risen, 40ml of coolant was taken, 10ml of argon gas was injected, and the mixture was shaken at 35°C for 10min and left to stand for 10min. The cycle of constant temperature shaking was repeated for 30min to allow the coolant-gas phase to reach gas-liquid equilibrium. A gas chromatograph was used with an MS detector configuration and a PorapkT column as the chromatographic column to detect the dissolved gas components. The results are shown in the following table.

[0045] Table 3

[0046]

[0047] Example 4

[0048] The coolant detected in this embodiment was taken from an immersion liquid-cooled battery fault simulation system. A 280Ah lithium iron phosphate battery was heated to thermal runaway with a heating power of 750W. It was detected that the battery surface temperature rose rapidly to above 235°C. 40ml of coolant was taken, 10ml of argon gas was injected, and the mixture was shaken at 35°C for 10min and left to stand for 10min. The mixture was cycled and shaken at a constant temperature for 30min to allow the coolant-gas phase to reach gas-liquid equilibrium. A gas chromatograph was used with an MS detector configuration and a PorapkT column as the chromatographic column to detect the dissolved gas components. The results are shown in the following table.

[0049] Table 4

[0050] 250℃ Gas composition Large amounts of hydrogen and small amounts of ethylene, propane, and carbon dioxide

[0051] The fire sensors of the simulation devices in all the above embodiments did not respond.

[0052] In summary, by early identification of thermal runaway characteristic gases, this method can provide earlier fault warning for the energy storage system, allowing maintenance and repair work to be carried out before the fault occurs, reducing unexpected downtime and potential safety risks caused by the fault.

[0053] This method can not only identify the existence of early faults, but also determine the specific cause of the fault by analyzing the type and content of specific gases, such as SEI film decomposition, negative electrode and electrolyte reaction, etc., providing a basis for accurate diagnosis and targeted repair of faults.

[0054] By promptly identifying and handling early faults, this method helps maintain the temperature balance and operating stability of the energy storage system, extend the battery life, and reduce battery damage and performance degradation caused by thermal runaway.

[0055] By enabling early detection and treatment of faults, this approach helps reduce the cost of large-scale repairs or battery replacements due to failures, thereby reducing overall maintenance costs.

[0056] In summary, the innovative method of this patent not only improves the safety and stability of the energy storage system, but also helps to reduce maintenance costs and environmental impacts, while enhancing users' trust in energy storage technology. It has important practical value and social significance.

[0057] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for early fault identification of an immersion liquid-cooled energy storage system, characterized in that: include, Take coolant from a sampling port of the immersion liquid-cooled energy storage system and store it in a syringe; Inject argon into the syringe and oscillate at a constant temperature to make the coolant-gas two phases reach gas-liquid equilibrium, and remove the characteristic gas dissolved in the coolant; Detect the content of thermal runaway characteristic gases in the gas; Identify early thermal runaway failures of energy storage batteries and systems based on characteristic gases.

2. The method for early fault identification of an immersion liquid-cooled energy storage system according to claim 1, characterized in that: The volume ratio of the cooling liquid to the argon gas is 3-5:

1.

3. The method for early fault identification of an immersion liquid-cooled energy storage system according to claim 1, characterized in that: The thermal runaway characteristic gases include hydrogen, carbon monoxide, carbon dioxide, ethylene, butane, and fluoromethane.

4. The method for early fault identification of an immersion liquid-cooled energy storage system according to claim 1, characterized in that: The constant temperature oscillation has an oscillation frequency of 250 to 300 times / min, an oscillation amplitude of 30 to 40 mm, a temperature of 35 to 50° C., and a total oscillation time of 20 to 50 min.

5. The method for early fault identification of an immersion liquid-cooled energy storage system according to claim 4, characterized in that: The constant temperature oscillation is continuous oscillation for 10 to 50 minutes and rest for 5 to 15 minutes.

6. The method for early fault identification of an immersion liquid-cooled energy storage system according to claim 1, characterized in that: The thermal runaway characteristic gas content is measured by gas chromatography.

7. The method for early fault identification of an immersion liquid-cooled energy storage system according to claim 6, characterized in that: The chromatographic column of the gas chromatography is selected from a silica gel column, a mixed stationary phase PorapkT column, a PLOT Q capillary column or other chromatographic columns capable of separating gases such as hydrogen, carbon monoxide, carbon dioxide, ethylene, butane, and fluoromethane.

8. The method for early fault identification of an immersion liquid-cooled energy storage system according to claim 6, characterized in that: The detector of the gas chromatography is selected from TCD, FID, MS or other detectors that respond to gases such as hydrogen, carbon monoxide, carbon dioxide, ethylene, butane, and fluoromethane.

9. The method for early fault identification of an immersion liquid-cooled energy storage system according to claim 1, characterized in that: The thermal runaway fault is identified by the type of characteristic gas; When the characteristic gas is ethylene or carbon dioxide, the fault type is the decomposition reaction of the SEI film at the solid electrolyte interface; When the characteristic gas is ethylene or propane, the fault type is a reaction between the negative electrode and the electrolyte; When the characteristic gas is hydrogen, the fault type is the reaction between the negative electrode and the binder PVDF or the early overcharge or overdischarge of the battery; When the characteristic gas is carbon dioxide or carbon monoxide, the fault type is a reaction between the positive electrode and the electrolyte; When the characteristic gas is fluoromethane, the fault type is decomposition reaction of the electrolyte.

10. The method for early fault identification of an immersion liquid-cooled energy storage system according to claim 9, characterized in that: When the characteristic gas is ethylene, the components of the electrolyte that reacts with the negative electrode are ethylene carbonate and diethyl carbonate; when the characteristic gas is propane, the components of the electrolyte that reacts with the negative electrode are ethylene carbonate and dimethyl carbonate.

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