Square-shell lithium ion storage battery shelving gas production detection method for space

Abstract

The invention relates to a space square-shell lithium ion storage battery shelving gas production detection method, and belongs to the technical field of lithium ion storage batteries. The method comprises the following steps: charging a formed and aged square-shell lithium ion storage battery to a full-charge state, taking out an electric pile, separating positive and negative electrodes, reassembling into three flexible package batteries, and shelving in the full-charge state; during the shelving period, the gas production condition is respectively detected through ultrasonic scanning, so that the problem that the aluminum shell battery is difficult to carry out visual gas production detection by directly using ultrasonic waves is solved, and meanwhile, the gas production source during the full-electric-state shelving period can be clearly identified, and different gas production behaviors caused by positive and negative electrodes are distinguished; and evaluating actual effects of electrolyte components, formation and aging processes of the square-shell lithium ion storage battery for the rapid space on inhibition of gas production during a full-electric-state shelving period according to the actual effects of the electrolyte components, the formation process and the aging process.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a method for detecting gas generation of a square-shell lithium ion battery for space use. Background Art

[0002] Lithium-ion batteries have the characteristics of high specific energy, high specific power and long cycle life, and have become an internationally recognized space energy storage power source. However, lithium-ion batteries produce a large amount of gas during the formation, storage and cycle process, which causes the contact between the positive and negative electrodes to deteriorate, the electrochemical reaction is insufficient, and the side reactions on the electrode surface are aggravated, thereby reducing the electrochemical performance of lithium-ion batteries; in addition, if the generated gas accumulates inside the battery cell, it will also cause lithium precipitation at the edge of the bubble, posing a safety hazard. The continuous gas production of lithium-ion batteries is mainly attributed to the unstable electrode / electrolyte interface, which is directly related to the electrolyte composition, formation and aging process system.

[0003] Lithium-ion batteries for space use are usually stored after the full period of illumination. At this time, the positive electrode is in a deep delithiation state and the negative electrode is in a deep lithium insertion state, both of which have high electrochemical catalytic activity. If a stable electrode / electrolyte interface is not constructed at this time, the occurrence of interfacial side reactions will be accelerated, causing the monomers to frequently produce gas during the storage period.

[0004] Existing lithium-ion batteries for space use use a sealed structure with an inner electrode group and an outer metal shell. The electrode groups with square shells are mostly stacked. Limited by the gas collection method and the lack of detection and analysis means, it is impossible to visualize the gas production of square-shell lithium-ion batteries for space use.

[0005] Chinese invention patent CN 115902648 A discloses a method and device for in-situ detection of gas production of soft-packaged batteries, which realizes in-situ detection of soft-packaged batteries by sealing the soft-packaged batteries in an in-situ mold and connecting the charge and discharge test system. However, this patent is only applicable to gas production detection of soft-packaged batteries, and cannot distinguish the gas production behavior of positive and negative electrodes. Summary of the invention

[0006] The purpose of the present invention is to provide a method for detecting gas production during storage of square-shell lithium-ion batteries for space use. The method separates the positive and negative electrodes and reassembles them into three soft-package batteries for fully charged storage. The gas production is detected separately by ultrasonic scanning, thereby overcoming the difficulty that it is difficult to directly use ultrasound to visually detect gas production of aluminum shell batteries. At the same time, the gas production source during storage can be clearly identified, and the different gas production behaviors caused by the positive and negative electrodes can be distinguished. Based on this, the actual effect of the electrolyte composition, formation and aging process of the rapid space square-shell lithium-ion battery on suppressing gas production during storage can be evaluated.

[0007] The above-mentioned purpose of the present invention is mainly achieved through the following technical solutions:

[0008] A method for detecting gas generation of a space-use square-shell lithium-ion battery when it is stored, comprising the following steps:

[0009] (1) Inject electrolyte into the test lithium-ion battery for formation aging;

[0010] (2) charging the lithium-ion storage battery obtained in step (1) to a fully charged state;

[0011] (3) placing the fully charged lithium-ion battery obtained in step (2) in a drying room, cutting open the battery casing, and taking out the battery stack;

[0012] (4) removing the separator of the lithium-ion battery obtained in step (3), taking out N positive electrodes and N+1 negative electrodes respectively, and leaving N positive electrodes and N+1 negative electrodes;

[0013] (5) The N positive electrodes, N+1 negative electrodes, and the remaining N positive electrodes and N+1 negative electrodes obtained in step (4) are reassembled into three types of soft-package batteries: N positive electrodes are assembled into a positive electrode stack soft package, N+1 negative electrodes are assembled into a negative electrode stack soft package, and N positive electrodes and N+1 negative electrodes are assembled into a full battery stack soft package;

[0014] (6) Injecting the electrolyte remaining in the lithium-ion battery shell into the three soft-package batteries respectively;

[0015] (7) The three soft-package batteries were stored under the same storage conditions as the square-shell lithium-ion batteries for space use;

[0016] (8) Detect the gas production of the three soft-package batteries obtained in step (7).

[0017] In the step (1), the electrolyte injected is 5 to 7 g / Ah, and the amount of electrolyte injected is 2 to 2.5 times the original amount of electrolyte injected.

[0018] In the step (2), the preset voltage of the full-power state is 4.1V to 4.4V.

[0019] In step (3), the dew point temperature of the drying room is ≤-30°C.

[0020] The number of pole pieces N is ≥10.

[0021] The thickness of the soft package battery is 3 mm to 15 mm.

[0022] The storage environment temperature is 20℃±5℃, and the relative humidity is 30%~70%.

[0023] The number of days of shelving is ≥ 28 days.

[0024] In the step (6), the ratios of the liquid injection amounts of the three soft-package batteries are 0.8-1.2: 0.8-1.2: 1.8-2.5, respectively.

[0025] In the step (8), the gas production detection method is as follows: three types of soft-packaged batteries are placed in silicone oil, an ultrasonic signal is applied to one side of the battery, and the ultrasonic detection signal is received on the other side after penetrating the battery; an HSV image can be visualized according to the intensity of the ultrasonic transmission, and the gas production of the soft-packaged battery can be judged according to the color change of the image.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] The present invention discloses a method for detecting gas generation during storage of square-shell lithium-ion batteries for space use, which overcomes the difficulty of visually detecting gas generation of aluminum-shell batteries by direct ultrasound. Meanwhile, the method can clearly identify the source of gas generation during storage, distinguish different gas generation behaviors caused by positive and negative electrodes, and evaluate the actual effect of electrolyte composition, formation and aging process of rapid square-shell lithium-ion batteries for space use on suppressing gas generation during storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of the method for detecting gas generation when a square-shell lithium-ion battery for space use is stored;

[0029] Figure 2 This is a visualization image of ultrasonic detection of the soft-package battery of the full-cell stack of Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0031] Figure 1 The present invention is a flow chart of a method for detecting gas generation when a square-shell lithium-ion battery for space is placed on standby, and the method for detecting gas generation when a square-shell lithium-ion battery for space is placed on standby comprises:

[0032] A method for detecting gas generation of a space-use square-shell lithium-ion battery when it is stored, characterized in that it comprises the following steps:

[0033] (1) Inject electrolyte into the test lithium-ion battery for formation aging;

[0034] (2) charging the lithium-ion storage battery obtained in step (1) to a fully charged state;

[0035] (3) placing the fully charged lithium-ion battery obtained in step (2) in a drying room, cutting open the battery casing, and taking out the battery stack;

[0036] (4) removing the separator of the lithium-ion battery obtained in step (3), taking out N positive electrodes and N+1 negative electrodes respectively, and leaving N positive electrodes and N+1 negative electrodes;

[0037] (5) The N positive electrodes, N+1 negative electrodes, and the remaining N positive electrodes and N+1 negative electrodes obtained in step (4) are reassembled into three types of soft-package batteries: N positive electrodes are assembled into a positive electrode stack soft package, N+1 negative electrodes are assembled into a negative electrode stack soft package, and N positive electrodes and N+1 negative electrodes are assembled into a full battery stack soft package;

[0038] (6) Injecting the electrolyte remaining in the lithium-ion battery shell into the three soft-package batteries respectively;

[0039] (7) The three soft-package batteries were stored under the same storage conditions as the square-shell lithium-ion batteries for space use;

[0040] (8) Detect the gas production of the three soft-package batteries obtained in step (7).

[0041] In the step (1), the electrolyte injected is 5 to 7 g / Ah, and the electrolyte injection amount is 2 to 2.5 times the normal injection amount.

[0042] The fully charged state preset voltage in step (2) is 4.1V to 4.4V.

[0043] The dew point temperature of the drying room in step (3) is ≤ –30°C.

[0044] The number of pole pieces N is ≥10.

[0045] The thickness of the soft package battery is 3 mm to 15 mm.

[0046] The storage environment temperature is 20℃±5℃, and the relative humidity is 30%~70%.

[0047] The number of days of storage is ≥ 28 days.

[0048] The gas production detection method described in step (8) is as follows: three soft-package batteries are placed in silicone oil, and ultrasonic signals are applied to one side of the battery. The ultrasonic detection signal is received on the other side after penetrating the battery; an HSV image can be visualized according to the intensity of ultrasonic transmission, and the gas production of the soft-package battery can be judged according to the color change of the image. When the ultrasonic transmission is strong, it proves that there is no gas production inside the soft-package battery; when the ultrasonic transmission is weak, it proves that there is gas production inside the soft-package battery. The gas production of the positive electrode, negative electrode and full battery can be clearly distinguished, thereby reflecting the gas production behavior of the square shell lithium-ion battery.

[0049] Example 1

[0050] Figure 2The figure shows a visualization image of ultrasonic detection of a soft-packaged battery of a full battery stack in this embodiment. This embodiment provides a method for detecting gas generation of a square-shell lithium-ion battery for space use, comprising the following steps:

[0051] (1) Charge the lithium-ion battery after formation and aging to 4.1V;

[0052] (2) Place the fully charged lithium-ion battery in a drying room with a dew point temperature of –45°C, use a laser cutting machine to cut the battery casing along a preset path, and take out the battery stack;

[0053] (3) Take out 10 positive electrodes and 11 negative electrodes respectively;

[0054] (4) The separated 10 positive electrode sheets, 11 negative electrode sheets, and the remaining 10 positive electrode sheets and 11 negative electrode sheets were reassembled into three different types of aluminum-plastic film soft-package batteries: positive electrode stack soft-package (10 positive electrode sheets), negative electrode stack soft-package (11 negative electrode sheets), and full battery stack soft-package (10 positive electrode sheets and 11 negative electrode sheets), with thicknesses of 4.97 mm, 6.92 mm, and 12.26 mm, respectively.

[0055] (5) The three soft-package batteries were stored under the same storage conditions as the square-shell lithium-ion batteries for space use, with an ambient temperature of 22.3°C, a relative humidity of 54%, and a storage period of 28 days.

[0056] (6) Ultrasonic testing was used to conduct a visual analysis of the gas production of three types of soft-package batteries at different storage days.

[0057] Ultrasonic tests were performed during the 0-day, 5-day, 10-day, 15-day and 28-day periods.

[0058] from Figure 2 It can be seen that the visualization image of the ultrasonic inspection of the soft package after 28 days of storage shows that the low transmission intensity area of ​​the positive electrode stack soft package is larger than that of the negative electrode stack soft package, indicating that the aluminum shell battery continues to produce gas during the storage period, and the gas production of the positive electrode is greater than that of the negative electrode, which further shows that the electrolyte composition, formation and aging process have not formed a stable positive electrode / electrolyte interface.

[0059] The above description is only the best specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

[0060] The contents not described in detail in the specification of the present invention belong to the common knowledge of professionals in the field.

Claims

1. A method for detecting gas generation of a space-use square-shell lithium-ion battery when it is stored, characterized in that: The following steps are involved: (1) Inject electrolyte into the test lithium-ion battery for formation aging; (2) charging the lithium-ion storage battery obtained in step (1) to a fully charged state; (3) placing the fully charged lithium-ion battery obtained in step (2) in a drying room, cutting open the battery casing, and taking out the battery stack; (4) removing the separator of the lithium-ion battery obtained in step (3), taking out N positive electrodes and N+1 negative electrodes respectively, and leaving N positive electrodes and N+1 negative electrodes; (5) The N positive electrodes, N+1 negative electrodes, and the remaining N positive electrodes and N+1 negative electrodes obtained in step (4) are reassembled into three types of soft-package batteries: N positive electrodes are assembled into a positive electrode stack soft package, N+1 negative electrodes are assembled into a negative electrode stack soft package, and N positive electrodes and N+1 negative electrodes are assembled into a full battery stack soft package; (6) Injecting the electrolyte remaining in the lithium-ion battery shell into the three soft-package batteries respectively; (7) The three soft-package batteries were stored under the same storage conditions as the square-shell lithium-ion batteries for space use; (8) Detect the gas production of the three soft-package batteries obtained in step (7).

2. A method for detecting gas generation of a square-shell lithium-ion battery for space use according to claim 1, characterized in that: In the step (1), the electrolyte injected is 5 to 7 g / Ah, and the amount of electrolyte injected is 2 to 2.5 times the original amount of electrolyte injected.

3. A method for detecting gas generation of a square-shell lithium-ion battery for space use according to claim 1, characterized in that: In the step (2), the preset voltage of the full-power state is 4.1V to 4.4V.

4. A method for detecting gas generation of a square-shell lithium-ion battery for space use according to claim 1, characterized in that: In the step (3), the dew point temperature of the drying room is ≤ -30°C.

5. A method for detecting gas generation of a space-use square-shell lithium-ion battery when stored as claimed in claim 1, characterized in that: The number of pole pieces N is ≥10.

6. A method for detecting gas generation of a space-use square-shell lithium-ion battery when stored as claimed in claim 1, characterized in that: The thickness of the soft package battery is 3 mm to 15 mm.

7. A method for detecting gas generation of a square-shell lithium-ion battery for space use according to claim 1, characterized in that: The storage environment temperature is 20℃±5℃, and the relative humidity is 30%~70%.

8. The method for detecting gas generation of a square-shell lithium-ion battery for space use according to claim 1, characterized in that: The number of days of shelving is ≥ 28 days.

9. A method for detecting gas generation of a square-shell lithium-ion battery for space use according to claim 1, characterized in that: In the step (6), the ratios of the liquid injection amounts of the three soft-package batteries are 0.8-1.2: 0.8-1.2: 1.8-2.5, respectively.

10. A method for detecting gas generation of a space-use square-shell lithium-ion battery when stored as claimed in claim 1, characterized in that: In the step (8), the gas production detection method is as follows: three types of soft-packaged batteries are placed in silicone oil, an ultrasonic signal is applied to one side of the battery, and the ultrasonic detection signal is received on the other side after penetrating the battery; an HSV image can be visualized according to the intensity of the ultrasonic transmission, and the gas production of the soft-packaged battery can be judged according to the color change of the image.

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