A secondary packaging method for a soft-pack battery and the soft-pack battery itself.

Abstract

This invention discloses a secondary packaging method for a pouch battery and the pouch battery itself, relating to the field of pouch battery packaging technology. The method includes the following steps: removing the outer aluminum-plastic film of the original pouch battery, leaving only the tab connection portion exposed, revealing the bare cell body; completely wrapping the bare cell with a new aluminum-plastic film according to the specifications required for cell modification; heat-sealing the aluminum-plastic film to the reserved tab portion using a multi-layer heat-sealing adhesive structure on one side of the tab; cooling after heat sealing; and performing a sealing check after cooling to determine if there is a risk of leakage. This invention avoids packaging defects caused by electrolyte residue during the secondary packaging process of the pouch battery and also eliminates the impact of the original disposable tab adhesive being non-reusable.

Description

Technical Field

[0001] This invention relates to the field of pouch battery packaging technology, and more particularly to a secondary packaging method for pouch batteries and a pouch battery. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Currently, batteries are categorized into cylindrical, prismatic, and pouch batteries based on their surface morphology and packaging methods. Pouch batteries, to prevent cracking during gas expansion and thus avoid further damage such as explosions, utilize an aluminum-plastic film encapsulation. This reduces weight by at least 20% compared to other battery types with aluminum or steel casings. Furthermore, pouch batteries exhibit less self-discharge and a longer cycle life. Therefore, compared to other battery types, pouch batteries offer higher energy density, lighter weight, lower internal resistance, and better cycle performance and safety. They also offer high flexibility in terms of appearance, allowing for the development of products in various sizes to meet different requirements, making them a promising candidate for the rapidly growing new energy power and energy storage market.

[0004] A crucial step in determining the quality of pouch batteries lies in their packaging. Currently, the main reason hindering the growth of pouch battery shipments is the limitation of packaging manufacturing technology, leading to reduced battery reliability and even a probability of leakage. If the packaging adhesion and sealing are insufficient, cracks can easily appear at the seal when the cell expands due to abnormal conditions, resulting in leakage. Even for products that have passed factory inspection, when anomalies occur and problem localization is needed, the battery needs to be disassembled to verify the internal failure mechanism. If issues such as electrolyte shortage, abnormal bonding, or casing abnormalities are found, the internal problems need to be addressed and the battery restored to its original state for testing. This verifies the reliability of theoretical predictions, accurately locates the problem point, and also verifies whether the internal failure damage of the battery is reversible. Due to the high space utilization of pouch batteries, it is difficult to use injection methods to replenish electrolyte when shortages occur. When researching new systems and controlling the amount of electrolyte, it is also necessary to add electrolyte to the pouch battery, repackage it, and restore it to its original state for exploratory testing. In the above scenarios, disassembling and repackaging a pre-packaged soft-pack battery can result in electrolyte residue, leading to bonding failure. Furthermore, the used tab adhesive is irreversible, and the seal cannot be guaranteed.

[0005] Existing innovations in soft-pack packaging technology mainly focus on improvements in soft-pack hot-pressing structures, packaging shell structures, and packaging equipment. For example, Chinese utility model patent CN214254553U, entitled "A Packaging Structure for a Soft-Pack Battery and a Soft-Pack Battery Using the Same," provides a packaging method that reinforces the angled area between the top and side sealing areas of the soft-pack battery, forming a sealed cell housing cavity inside the aluminum-plastic film. This solves the problem of leakage that may occur in the battery body during cell expansion. Another Chinese utility model patent, CN215816059U, entitled "A Packaging Structure and a Soft-Pack Battery," forms a packaging shell with transitional sidewalls by stamping the packaging film, thereby avoiding stress concentration and mitigating the problem of easy deformation of sharp corner structures. However, current technologies rarely consider secondary packaging, failing to overcome the packaging defects caused by electrolyte residue during secondary packaging and the non-reusability of the original disposable tab adhesive. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a secondary packaging method for soft-pack batteries and a soft-pack battery, overcoming the problems that arise in the disassembly and repackaging of soft-pack batteries in existing failure analysis and system development. This method can avoid poor packaging caused by electrolyte residue and also eliminate the impact of the original disposable tab adhesive being non-reusable.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] The first aspect of this invention provides a secondary packaging method for a pouch battery, comprising the following steps:

[0009] The original soft-pack battery's outer aluminum-plastic film was removed, leaving only the tab connection part exposed to reveal the bare cell body.

[0010] The bare battery cells were completely wrapped with new aluminum-plastic film according to the specifications required for the battery cell modification.

[0011] On one side of the electrode tab, a multi-layer heat-sealing adhesive structure is used to heat-seal and bond the aluminum-plastic film to the reserved electrode tab portion.

[0012] After heat sealing, the mixture is cooled. Once the bonding effect is achieved after cooling, a sealing test is performed to determine if there is any risk of leakage.

[0013] Furthermore, the original soft-pack battery's outer aluminum-plastic film was removed in a waterless vacuum glove box environment.

[0014] Furthermore, the multilayer heat-sealing adhesive structure includes three uniform layers: upper, middle, and lower. The upper and lower layers are both made of high-molecular-weight polyester materials, while the middle layer is used for support and is made of metal or modified resin film materials.

[0015] Furthermore, the thickness of the upper or lower layer ranges from 30 to 50 μm.

[0016] Furthermore, the intermediate layer is made of one of copper, nickel, or aluminum, and its thickness ranges from 10 to 40 μm.

[0017] Furthermore, the overall thickness of the multilayer heat-sealing adhesive structure ranges from 100 to 150 μm.

[0018] Furthermore, the specific steps for heat-sealing and bonding the aluminum-plastic film to the pre-reserved electrode tab portion using a multi-layer heat-sealing adhesive structure on one side include:

[0019] The heat sealing machine is preheated, and the temperature of the heat sealing machine is waited for it to reach the preset temperature and stabilize.

[0020] The multi-layer heat-sealing adhesive structure is cut into narrow strips;

[0021] A multi-layer heat-sealing adhesive structure is applied to the tab connection area, and a new aluminum-plastic film is applied on top. The covered soft-pack battery is then placed under a preheated heat-sealing machine for heat sealing.

[0022] Repeated heat sealing ensures that the PP layer on the aluminum-plastic film surface and the tab connection part can be tightly bonded to the upper and lower surfaces of the multi-layer heat-sealing adhesive structure.

[0023] Furthermore, the heat sealing machine temperature is set to 180-260℃, and the heat sealing time is 3-5 seconds per cycle.

[0024] Furthermore, after heat sealing, allow it to cool for 15-30 minutes.

[0025] The second aspect of the present invention provides a pouch battery, which is manufactured by encapsulating the pouch battery using the secondary encapsulation method described in the first aspect.

[0026] The above one or more technical solutions have the following beneficial effects:

[0027] This invention discloses a secondary packaging method for a soft-pack battery and the soft-pack battery. The method does not damage the original tabs when replacing the aluminum-plastic film, and the internal core is not damaged during the secondary packaging process, thus achieving non-destructive liquid replenishment.

[0028] The secondary encapsulation method of the present invention has no impact on the encapsulation process when residual electrolyte is present; the multi-layer heat-sealing adhesive structure replaces the adhesive on the tabs, which is green and environmentally friendly and will not affect the battery performance.

[0029] The encapsulation process of this invention is simple to operate and has a wide range of applications. It can be used not only in the secondary encapsulation process, but also in the primary encapsulation process of battery production. A multi-layer heat-sealing adhesive structure can be used to replace the adhesive on the tabs, so as to achieve a tight fit between the metal interface and the aluminum-plastic film outer packaging and reduce the probability of leakage.

[0030] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 This is a schematic diagram of the secondary packaging process of the soft-pack battery in Embodiment 1 of the present invention;

[0033] Figure 2 This is a schematic diagram of the multilayer heat-sealing adhesive structure in Embodiment 1 of the present invention;

[0034] Figure 3 This is a test diagram of the electrical performance of the soft-pack battery after secondary packaging in Embodiment 1 of the present invention;

[0035] Among them, 1. upper layer, 2. middle layer, 3. original aluminum-plastic film, 4. tab, 5. original tab adhesive, 6. new aluminum-plastic film, 7. cavity for battery cell, 8. multi-layer heat-sealing adhesive structure. Detailed Implementation

[0036] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] Example 1:

[0039] Soft-pack batteries possess advantages such as high space utilization, high battery capacity, and good cycle performance, but they also suffer from insufficient battery strength and weak impact resistance. Existing packaging processes typically involve dry cell packaging before electrolyte injection, where adhesives fixed to the tabs are bonded to an aluminum-plastic film at high temperatures. However, in some non-dry cell packaging cases, the viscosity of the tab adhesive in contact with the electrolyte significantly decreases, limiting the applicability of this method. Based on the aforementioned shortcomings of existing packaging technologies, this invention innovates a repackaging technology for soft-pack batteries. The aim is to overcome the problems encountered in disassembling and repackaging soft-pack batteries during existing failure analysis and system development. This technology avoids packaging defects caused by electrolyte residue and eliminates the impact of the original single-use tab adhesive being non-reusable. Furthermore, the multi-layer heat-sealing adhesive structure of this invention can be used for packaging any tab without attached adhesive, and for packaging three-electrode reference electrodes, etc.

[0040] Embodiment 1 of this invention provides a secondary encapsulation method for pouch batteries. In a vacuum glove box, the original pouch battery to be analyzed or replenished is covered with an aluminum-plastic film, leaving the interface between the tabs and the aluminum-plastic film exposed. During re-encapsulation, the multi-layer heat-sealing adhesive structure of this invention is inserted. This multi-layer heat-sealing adhesive re-encapsulation technology uses a novel three-layer structure for bonding the tabs to the aluminum-plastic film. The top and bottom layers of this structure are made of polyester material, with a metal support layer in the middle, and the materials used are compatible with both the metal and the aluminum-plastic film. Finally, the new aluminum-plastic film and the tabs are repeatedly heat-sealed at a preset heat-sealing machine temperature to check for sealing performance and leakage risks.

[0041] Specifically, the following steps are included:

[0042] Step 1: Remove the outer aluminum-plastic film of the original soft-pack battery, leaving only the tab connection part exposed to reveal the bare battery cell body.

[0043] In this embodiment, the outer aluminum-plastic film of the original soft-pack battery is removed in an anhydrous vacuum glove box environment.

[0044] Step 2: Completely wrap the bare battery cell with new aluminum-plastic film according to the specifications required for the battery cell modification.

[0045] Step 3: Use a multi-layer heat-sealing adhesive structure to heat-seal and bond the aluminum-plastic film to the reserved tab portion on one side of the electrode.

[0046] like Figure 2As shown, the multilayer heat-sealing adhesive structure comprises three uniform layers, resembling a "sandwich." The top and bottom layers are bonded together by heat fusion, with a support layer in the middle, secured by the mutual pressure between the layers. The top and bottom layers are both made of high-molecular-weight polyester material, while the middle layer 2 provides support and is made of metal or modified resin film material. The overall thickness of the multilayer heat-sealing adhesive structure ranges from 100-150 μm. The top and bottom layers have the same thickness, ranging from 30-50 μm. When the middle layer is made of a metal material, it is one of copper, nickel, or aluminum, and is coated with an insulating resin material; the thickness of the middle layer ranges from 10-40 μm. This embodiment of the multilayer heat-sealing adhesive structure exhibits good insulation at room temperature. In electrolyte resistance tests, whether bonded to metal or aluminum-plastic film connectors or as standalone connectors, it demonstrates a tight bond without delamination or detachment.

[0047] On one side of the electrode tab, the aluminum-plastic film is heat-sealed to the reserved electrode tab using a multi-layer heat-sealing adhesive structure. The specific steps include:

[0048] (1) Set the heat sealing machine temperature to 180-260℃, preheat the heat sealing machine, and wait for the heat sealing machine temperature to reach the preset temperature and stabilize.

[0049] (2) Cut the multi-layer heat-sealing adhesive structure into narrow strips, with the specific dimensions varying according to the size of the soft-pack battery.

[0050] (3) Cover the tab connection with a multi-layer heat-sealing adhesive structure, cover the top with a new aluminum-plastic film, and place the covered soft-pack battery under a preheated heat-sealing machine for heat sealing.

[0051] (4) Repeat the heat sealing process multiple times, with each heat sealing time being 3-5 seconds, so that the PP layer on the surface of the aluminum-plastic film and the electrode tab connection part can be tightly bonded to the upper and lower surfaces of the multi-layer heat-sealing adhesive structure.

[0052] The multilayer heat-sealing adhesive of this embodiment can re-encapsulate the battery after disassembly using a special high-molecular polyester material. This material has a high degree of adhesion to metals and PP, excellent thermoplasticity, and can greatly reduce the impact of electrolyte on the encapsulation, making it superior to other heat-sealing adhesives.

[0053] Step 4: After heat sealing, allow to cool for 15-30 minutes. Once cooling is complete and the bonding effect is achieved, perform a sealing check to determine if there is any risk of leakage.

[0054] To better understand the encapsulation method described in the embodiments, the encapsulation process of placing conductive materials such as nickel strips, copper strips, and alloys within a three-electrode system as reference electrode substrates into a soft-pack battery, and the re-encapsulation process of a failed battery based on electrical performance testing and analysis, are used as examples to illustrate the encapsulation experiment.

[0055] Packaging Experiment 1:

[0056] In a three-electrode system, conductive materials such as nickel strips, copper strips, and alloys serve as the reference electrode substrate within a pouch cell. The pouch cell tabs themselves have tab adhesive for initial encapsulation, but the substrate for the subsequently added reference electrode typically lacks a sealing adhesive structure. The multilayer heat-sealing adhesive structure of this embodiment solves the above problem. The specific steps are as follows:

[0057] (1) After a series of operations such as die cutting, stacking, and punching of soft-pack batteries, a reference electrode coated with active material is added between the electrodes of the stacked cells.

[0058] (2) Fix the reference electrode on the PVDF film between the electrode plates. The placement position is located at the midpoint of the straight distance between the positive and negative electrode tabs. Ensure that the upper layer of the reference electrode is covered to prevent the stacked shape from being restored after short circuit.

[0059] (3) Cut the multi-layer heat sealant structure into narrow strips. In this embodiment, the nickel strip used has a width of 0.5cm, a heat sealant thickness of 100μm, and a size of 1×1cm.

[0060] (4) Place a multi-layer heat-sealing adhesive structure at the junction of the reference electrode and the aluminum-plastic film, set the temperature of the heat sealer to 180°C, and wait for the temperature to reach the preset temperature and stabilize.

[0061] (5) Then, heat seal the tabs together with the normal packaging process. The heat sealing time is 3-6 seconds. In this embodiment, 5 seconds is used, and the heat sealing is repeated twice.

[0062] (6) After removing the product from the heat sealing machine and cooling it for 15 minutes, a leak test was performed on the finished product. The results showed that the sealing performance was good, indicating that the solution ensured the quality of the encapsulation.

[0063] Packaging Test 2:

[0064] The battery to be analyzed was disassembled in a vacuum glove box. Based on the electrical performance test analysis and preliminary disassembly, the failed battery has electrolyte loss and electrolyte shortage issues. To verify the hypothesis, electrolyte replenishment and repackaging are required.

[0065] The specific operating procedures are as follows: Figure 1 As shown:

[0066] (1) Cut the original soft-pack battery at the connection between the tab 4 and the aluminum-plastic film, remove the original aluminum-plastic film 3 outer packaging, expose the inner core, and leave only the part of the tab 4 in contact with the film.

[0067] (2) Take a new aluminum-plastic film 6 to accommodate the cell punching hole 7, and wrap the removed bare core with the new aluminum-plastic film.

[0068] (3) A multi-layer heat-sealing adhesive structure 8 is applied to the junction of the separated battery cell tabs and the aluminum-plastic film. This multi-layer heat-sealing adhesive structure 8 can be applied continuously to the entire boundary, or it can be cut into two pieces with a width exceeding 1 cm from both ends of the positive and negative tabs and placed on the sealing edges of the two tabs respectively. During the application of the multi-layer heat-sealing adhesive structure, the original tab adhesive can be retained.

[0069] (4) During the bonding process, the heat sealing machine temperature is set to 200℃ for high-temperature heat melting.

[0070] (5) Heat sealing time is 4 seconds, and the heat pressing is repeated twice.

[0071] (6) After the tab is sealed, the remaining sides are heat-sealed and liquid is added. After the predetermined amount of liquid is added, the injection port is sealed to obtain a brand new repackaged soft pack battery.

[0072] (7) The capacity was restored after a cyclic test, which shows that the technology has a good application effect.

[0073] Example 2:

[0074] Embodiment 2 of the present invention provides a soft-pack battery, which is manufactured by encapsulating the soft-pack battery using the secondary encapsulation method described in Embodiment 1.

[0075] The above Example 2 corresponds to Example 1. For specific implementation details, please refer to the relevant description section of Example 1.

[0076] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for secondary packaging of a soft-pack battery, characterized in that, Includes the following steps: The original soft-pack battery's outer aluminum-plastic film was removed, leaving only the tab connection part exposed to reveal the bare cell body. The bare battery cells were completely wrapped with new aluminum-plastic film according to the specifications required for the battery cell modification. On one side of the electrode tab, a multi-layer heat-sealing adhesive structure is used to heat-seal and bond the aluminum-plastic film to the reserved electrode tab portion. The specific steps include: The heat sealing machine is preheated, and the temperature of the heat sealing machine is waited for it to reach the preset temperature and stabilize. The multi-layer heat-sealing adhesive structure is cut into narrow strips; A multi-layer heat-sealing adhesive structure is applied to the tab connection area, and a new aluminum-plastic film is applied on top. The covered soft-pack battery is then placed under a preheated heat-sealing machine for heat sealing. Repeated heat sealing ensures that the PP layer on the aluminum-plastic film surface and the tab connection part can be tightly bonded to the upper and lower surfaces of the multi-layer heat-sealing adhesive structure; The multilayer heat-sealing adhesive structure includes three uniform layers: upper, middle, and lower. The upper and lower layers are both made of high-molecular polyester materials, while the middle layer is used for support and is made of metal or modified resin film materials. After heat sealing, the mixture is cooled. Once the bonding effect is achieved after cooling, a sealing test is performed to determine if there is any risk of leakage.

2. The secondary packaging method for a soft-pack battery as described in claim 1, characterized in that, Remove the outer aluminum-plastic film of the original soft-pack battery in an anhydrous vacuum glove box environment.

3. The secondary packaging method for a soft-pack battery as described in claim 1, characterized in that, The thickness of the upper or lower layer ranges from 30 to 50 μm.

4. The secondary packaging method for a soft-pack battery as described in claim 1, characterized in that, The intermediate layer is made of one of the following metal materials: copper, nickel, or aluminum, and its thickness ranges from 10 to 40 μm.

5. The secondary packaging method for a soft-pack battery as described in claim 1, characterized in that, The overall thickness of the multi-layer heat-sealing adhesive structure ranges from 100 to 150 μm.

6. The secondary packaging method for a soft-pack battery as described in claim 1, characterized in that, Set the heat sealing machine temperature to 180-260℃, and the heat sealing time for each operation is 3-5 seconds.

7. The secondary packaging method for a soft-pack battery as described in claim 1, characterized in that, After heat sealing, allow to cool for 15-30 minutes.

8. A pouch battery, manufactured by encapsulating the pouch battery using the secondary encapsulation method according to any one of claims 1-7.

Images