Exhaust structure and system for battery formation and formation method

Abstract

The invention discloses an exhaust structure and system for battery formation and a formation method, the exhaust structure comprises: a connecting pipe, one end of which is arranged at the edge of a sealed battery pack, so that the space in the sealed battery pack is communicated with the connecting pipe; and the one-way valve is positioned outside the sealed battery pack and is communicated with the other end of the connecting pipe. The formation method comprises the following steps: (1) when the aluminum-plastic film is subjected to first heat sealing, one end of the connecting pipe with the exhaust structure is fixedly connected with the edge of the aluminum-plastic film in a heat sealing manner to form a sealed battery pack with the exhaust structure, and the connecting pipe is far away from a battery cell area; (2) placing the sealed battery pack in formation equipment, and connecting an exhaust structure with negative pressure equipment; (3) performing formation on the battery cells in the sealed battery pack, and extracting gas in the sealed battery pack through an exhaust structure in the formation process until formation is completed; (4) performing second heat sealing on the sealed battery pack, taking an area between the first heat sealing and the second heat sealing as a redundant part, and communicating the exhaust structure with the redundant part; and (5) cutting off the redundant part to obtain a soft package battery product. The method is compatible with the existing soft package battery formation process, the packaging operation is simple, the use of an aluminum plastic film is reduced, and the production cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion battery formation, and in particular relates to an exhaust structure, system and formation method for battery formation. Background Art

[0002] Soft-pack lithium battery refers to a lithium battery whose outer shell is encapsulated by aluminum-plastic composite film. In the production process of lithium-ion batteries, there is a battery formation stage, which is the first charging link of the battery cell after injection. Its purpose is to activate the active substances in the battery, especially to form the SEI film, so that the battery performance is more stable.

[0003] Due to the characteristics of lithium-ion battery materials, gas will be generated during the formation stage. Therefore, the aluminum-plastic film of soft-pack lithium batteries is divided into one-sealing and two-sealing operations. In the first sealing, space is reserved to store the gas generated during the formation. After the formation is completed, the second sealing is performed to seal the battery area. The excess gas exists in the sealed area formed by the two seals. The sealed area is cut off to separate the battery from the gas.

[0004] Conventional lithium-ion battery formation reserves a certain area to store gas, which requires the consumption of a large amount of aluminum-plastic film, especially when producing large soft-pack batteries, which requires more aluminum-plastic film materials to accommodate gas. The price of aluminum-plastic film is relatively high, and the aluminum-plastic film used to store gas is directly consumed. If lithium supplements, such as lithium squarate, are added to the lithium-ion battery, more gas will be generated during the formation stage, and the use of aluminum-plastic film will increase significantly. Reducing the use of aluminum-plastic film during the formation stage has become a common goal of the industry. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide an exhaust structure, system and formation method for battery formation, which are compatible with the existing soft-pack battery formation process, have simple packaging operation, are conducive to reducing the use of aluminum-plastic film, and reduce production costs.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect of the present invention, the present invention provides an exhaust structure for battery formation, connected to a sealed battery pack formed by an aluminum-plastic film, the exhaust structure comprising:

[0008] A connecting tube, one end of which is arranged at the edge of the sealed battery pack, so that the space inside the sealed battery pack is connected to the connecting tube.

[0009] The one-way valve is located outside the sealed battery pack and is connected to the other end of the connecting tube, allowing gas to be discharged from the sealed battery pack and restricting gas from entering the sealed battery pack.

[0010] Preferably, a tab glue layer is provided on the side of one end of the connecting tube connected to the sealed battery pack, and is fixedly connected to the aluminum-plastic film when the aluminum-plastic film is heat-sealed.

[0011] Preferably, the connecting tube is a plastic part, and more preferably, the connecting tube is a plastic part that can withstand the heat-sealing temperature of the aluminum-plastic film.

[0012] Preferably, the one-way valve is a plastic part.

[0013] Preferably, the connecting pipe is detachably connected to the one-way valve.

[0014] Preferably, the connecting tube includes a front tube and a rear tube, one end of the front tube is fixedly connected to the sealed battery pack, the other end of the front tube away from the sealed battery pack is sealed, the rear tube is connected to the one-way valve, an exhaust needle is provided at one end of the rear tube away from the one-way valve, and the exhaust needle of the rear tube is inserted into the end face of the front tube to connect the front tube with the rear tube.

[0015] More preferably, the end of the front tube away from the connecting tube is recessed inward to form an engaging groove, and the end of the rear tube away from the one-way valve is interference fit with the engaging groove of the front tube, so that the front tube and the rear tube are tightly connected.

[0016] In a second aspect of the present invention, the present invention further provides a system for battery formation, comprising a formation device and a negative pressure device, wherein the negative pressure device is connected to the exhaust structure.

[0017] In the third aspect of the present invention, the present invention also proposes a formation method, comprising:

[0018] (1) When the aluminum-plastic film is heat-sealed for the first time, one end of the connecting tube of the exhaust structure is heat-sealed and fixed to the edge of the aluminum-plastic film to form a sealed battery pack with an exhaust structure, and the connecting tube is away from the battery cell area;

[0019] (2) placing the sealed battery pack in a formation device, and connecting the exhaust structure to the negative pressure device;

[0020] (3) forming the battery cells in the sealed battery pack, and during the formation process, extracting the gas in the sealed battery pack through the exhaust structure until the formation is completed;

[0021] (4) performing a second heat seal on the sealed battery pack, with the area between the first heat seal and the second heat seal serving as a redundant portion, and the exhaust structure being connected to the redundant portion;

[0022] (5) The redundant part is cut off to obtain a soft-pack battery product.

[0023] Preferably, in step (3), after the formation is completed, the portion of the connecting tube outside the sealed battery pack is heat-sealed.

[0024] Beneficial effects:

[0025] The present invention is applicable to the existing formation process, and only requires adding an exhaust device to the sealed battery pack formed by the aluminum-plastic film, connecting the one-way valve to the negative pressure device, and the gas generated during the formation process is discharged through the one-way valve along the connecting pipe. Therefore, the area used to retain the gas in the sealed battery pack can be greatly reduced, thereby reducing the amount of aluminum-plastic film used and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Shown is a schematic diagram of the use of the present invention;

[0027] Figure 2 Shown is a schematic diagram of an embodiment of the present invention;

[0028] Figure 3 Shown is a schematic diagram of another embodiment of the present invention;

[0029] Figure 4 Shown is a schematic diagram of the formation process of the present invention.

[0030] Reference numerals: 1-exhaust structure, 2-battery cell, 3-aluminum-plastic film, 4-sealed battery pack, 5-ear, 6-gas storage area;

[0031] 11-connecting pipe, 12-check valve, 13-ear rubber layer, 14-front pipe, 15-rear pipe, 16-exhaust needle, 17-fitting groove. DETAILED DESCRIPTION

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0033] like Figure 1-4 As shown, the present invention proposes an exhaust structure for battery formation, which is connected to the sealed battery pack 4 formed by the aluminum-plastic film 3 to form a new sealed space. When the exhaust structure 1 is provided, the gas generated during the formation stage of the battery cell 2 can be directly discharged, and since a special space for storing gas is no longer required, the amount of the aluminum-plastic film 3 can be greatly reduced.

[0034] The exhaust structure 1 includes a connecting pipe 11 and a one-way valve 12. Specifically, one end of the connecting pipe 11 is arranged at the edge of the sealed battery pack 4 so that the space inside the sealed battery pack 4 is connected to the connecting pipe 11, and the other end of the connecting pipe 11 is connected to the one-way valve 12, and the one-way valve 12 is outside the sealed battery pack 4.

[0035] In the exhaust structure 1, the function of the connecting tube 11 is to form an exhaust channel so that the sealed battery pack 4 is connected to the outside. It should be noted that "connected to the outside" does not mean that the sealed battery pack 4 is not in a sealed state, but refers to the connecting function of the connecting tube 11. The function of the connecting tube 11 is to extend the exhaust channel. The one-way valve 12 allows gas to be discharged from the sealed battery pack 4 and restricts gas from entering the sealed battery pack 4.

[0036] Generally speaking, after the first sealing of the aluminum-plastic film 3 is completed, the internal battery cell 2 needs to be completely isolated from the outside world, especially during the formation process, the battery cell 2 must be prevented from contacting the outside atmosphere. The exhaust structure 1 is formed as a whole with the sealed battery pack 4. It should be noted that part or all of the exhaust structure 1 forms a whole with the sealed battery pack 4, as long as the sealed battery pack 4 is kept in a sealed state.

[0037] The conventional sealed battery pack 4 is formed by placing the battery cell 2 on the aluminum-plastic film 3, turning up one side of the aluminum-plastic film 3 to cover the battery, and heat-sealing the two layers of the aluminum-plastic film 3 along the edge, that is, Figure 1 The aluminum-plastic film 3 is heat-sealed at the middle seal, side seal and top seal positions, thereby forming a sealed space between the two layers of aluminum-plastic film 3. During heat sealing, the pole ear 5 is placed at the edge of the two layers of aluminum-plastic film 3 and heat-sealed together. This is the first sealing or heat sealing. Since the heat sealing of the aluminum-plastic film 3 and the setting of the pole ear 5 are common steps in existing soft-pack lithium batteries, the present invention will not repeat them. In the prior art, the sealed space is filled with battery components such as positive electrode, negative electrode, diaphragm, electrolyte, etc., and a gas storage area 6 is reserved. After the formation is completed, the second sealing is performed in the middle position of the sealed package, that is, along the Figure 1 The aluminum-plastic film 3 is heat-sealed at the middle second sealing position to separate the battery storage space from the gas storage area 6. The portion of the sealed package 4 corresponding to the gas storage area 6 is cut off, and the remaining sealed package is the soft-pack lithium battery.

[0038] A pole ear glue layer 13 is arranged on the side of one end of the connecting tube 11 connected to the sealed battery pack 4, and is fixedly connected to the aluminum-plastic film 3 when the aluminum-plastic film 3 is heat-sealed. The present invention is applicable to the existing heat-sealing process of the sealed battery pack 4. When sealing, the connecting tube 11 is placed on the edge of the aluminum-plastic film 3 and heat-sealed together, so that the connecting tube 11 is connected to the sealed battery pack 4 as a whole. The present invention is also applicable to the existing formation equipment, so as to optimize the formation process at the lowest cost. Based on this, the present invention also proposes a system for battery formation, including the existing formation equipment, and also including a negative pressure device, the negative pressure device is connected to the one-way valve 12 of the exhaust structure 1, and the gas generated in the sealed battery pack 4 is extracted during the formation process. In the existing formation process, only one negative pressure device is added, the negative pressure device is connected to the exhaust structure 1, and the gas is continuously or intermittently exhausted during the formation process to extract the generated gas. Since the exhaust structure 1 is provided with a one-way valve 12, the state of the battery cell 2 being isolated from the outside world can still be maintained in the gap where the negative pressure device is not exhausted.

[0039] It is easy to understand that the exhaust structure 1 of the present invention is to reduce the volume of the gas storage area 6 in the sealed battery pack 4, that is, to reduce the amount of aluminum-plastic film 3, but it does not completely eliminate the gas storage area 6 of the sealed battery pack 4. After the formation is completed, the sealed battery pack 4 still needs to be sealed twice, and the aluminum-plastic film 3 between the first and second seals is cut off. Therefore, the exhaust structure 1 is arranged on one side of the gas storage area 6 of the sealed battery pack 4. When cutting, the exhaust structure 1 is removed, and the remaining part is a soft-pack battery product.

[0040] Since part or all of the exhaust structure 1 needs to be cut off and discarded, in order to reduce the material cost of the exhaust structure 1, preferably, the connecting tube 11 is made of plastic material, and more preferably, the connecting tube 11 is made of high temperature resistant plastic, for example, the connecting tube 11 is a plastic part that can withstand the heat sealing temperature of the aluminum-plastic film 3 to avoid deformation during the heat sealing process. It should be noted that the heat sealing temperature of the aluminum-plastic film 3 is generally 120-180°C. For the connecting tube 11, when a higher temperature is used to contact the connecting tube 11, the connecting tube 11 itself can also be heat-sealed.

[0041] Preferably, the one-way valve 12 is also made of plastic. For example, the one-way valve 12 can be an existing medical one-way valve 12 .

[0042] The connecting pipe 11 and the one-way valve 12 made of plastic not only reduce the production cost, but also have the advantages of lightness and stability.

[0043] The connecting tube 11 serves as an intermediate component connecting the sealed battery pack 4 and the one-way valve 12. It can be a hard tube or a hose. Since the one-way valve 12 needs to be connected to the negative pressure equipment, the connecting tube 11 is preferably a hose to facilitate the adjustment of the position between the sealed battery pack 4 and the negative pressure equipment and the formation equipment.

[0044] The present invention does not impose any restriction on the diameter of the connecting tube 11. It is easy to understand that the main function of the connecting tube 11 is exhaust. As long as the diameter of the connecting tube 11 can meet the free flow of gas in the connecting tube 11, preferably, the diameter of the connecting tube 11 outside the sealed battery pack 4 is less than or equal to the diameter of the connecting part of the connecting tube 11 and the sealed battery pack 4.

[0045] Based on the setting of the exhaust structure 1, the present invention also improves the existing chemical formation method and proposes a new chemical formation method, including the following steps:

[0046] (1) When the aluminum-plastic film 3 is heat-sealed for the first time, one end of the connecting tube 11 of the exhaust structure 1 is heat-sealed and fixed to the edge of the aluminum-plastic film 3 to form a sealed battery pack 4 with the exhaust structure 1, and the connecting tube 11 is away from the battery cell 2 area;

[0047] (2) placing the sealed battery pack 4 in the formation equipment, and connecting the exhaust structure 1 to the negative pressure equipment;

[0048] (3) forming the battery cells 2 in the sealed battery pack 4. During the forming process, the gas in the sealed battery pack 4 is extracted through the exhaust structure 1 until the forming is completed;

[0049] (4) performing a second heat seal on the sealed battery pack 4, with the area between the first heat seal and the second heat seal serving as a redundant portion, and the exhaust structure 1 being connected to the redundant portion;

[0050] (5) The redundant part is cut off to obtain a soft-pack battery product.

[0051] Preferably, in step (3), after formation is completed, the portion of the connecting tube 11 outside the sealed battery pack 4 is heat-sealed. This operation is conducive to ensuring the airtight state of the sealed battery pack 4, and no longer relies on the one-way valve 12 to maintain the sealed state of the sealed battery pack 4. After separation from the negative pressure equipment, the one-way valve 12 can be recovered. It should be noted that the heat-sealing temperature of the connecting tube 11 itself is higher than the heat-sealing temperature of the aluminum-plastic film 3. When the aluminum-plastic film 3 is heat-sealed, the connecting tube 11 does not deform. When the connecting tube 11 is heat-sealed, the connecting tube 11 is contacted and melted at the part that contacts the high temperature.

[0052] In the present invention, the exhaust structure 1 can be an integrated structure, that is, the connecting pipe 11 and the one-way valve 12 are fixedly connected. The exhaust structure 1 of the integrated structure is connected to the sealed battery pack 4 as a whole, that is, each sealed battery pack 4 is connected to one exhaust structure 1, and the one-way valve 12 isolates the space inside the sealed battery pack 4 from the outside.

[0053] For the integrated exhaust structure 1, in step (1), the exhaust structure 1 is connected to the sealed battery pack 4 as a whole, and in step (5), the exhaust structure 1 is cut off along with the redundant parts and separated from the soft-pack battery product.

[0054] In the present invention, the exhaust structure 1 may also be a split structure to achieve the recycling and reuse of some parts, which is beneficial to further reduce the cost of the exhaust structure 1.

[0055] The split exhaust structure 1 includes but is not limited to the following two types:

[0056] Structure 1: Figure 2 As shown, the connecting pipe 11 is detachably connected to the one-way valve 12 , for example, the end of the connecting pipe 11 is interference fit with the one-way valve 12 , or the end of the connecting pipe 11 is threadedly connected to the one-way valve 12 .

[0057] In step (1), after the connection tube 11 and the aluminum-plastic film 3 are fixed, the one-way valve 12 is connected to the connection tube 11. At this time, the one-way valve 12 forms a sealed space between the sealed battery pack 4 and the connection tube 11. In step (3), after the formation is completed, the middle part of the connection tube 11 is heat-sealed, and then the one-way valve 12 is separated from the connection tube 11 and the one-way valve 12 is recovered. After the redundant part is cut off, only the connection tube 11 is discarded with the redundant part, and the one-way valve 12 can be returned to step (1) for reuse.

[0058] Structure 2: Figure 3 As shown, the structure of the connecting tube 11 is further improved. The connecting tube 11 includes a front tube 14 and a rear tube 15. One end of the front tube 14 is fixedly connected to the sealed battery pack 4, and the other end of the front tube 14 away from the sealed battery pack 4 is sealed. The rear tube 15 is connected to the one-way valve 12, and an exhaust needle 16 is provided at one end of the rear tube 15 away from the one-way valve 12. The exhaust needle 16 of the rear tube 15 is inserted into the end face of the front tube 14 to connect the front tube 14 with the rear tube 15.

[0059] The structure of the connecting tube 11 is divided into two parts, which is easy to understand. Before the front tube 14 and the rear tube 15 are connected, the front tube 14 and the sealed battery pack 4 are actually in a sealed state.

[0060] Based on structure 2, in step (1), after the front tube 14 and the aluminum-plastic film 3 are fixed, the sealed battery pack 4 is connected to the front tube 14 to maintain a sealed state; in step (2), the one-way valve 12 is connected to the negative pressure device, and the exhaust needle 16 of the rear tube 15 is inserted into the end face of the front tube 14 to achieve communication between the front tube 14 and the rear tube 15; in step (3), after the formation is completed, the front tube 14 is heat-sealed, and then the front tube 14 and the rear tube 15 are separated, and the one-way valve 12 and the rear tube 15 remain connected to the negative pressure device.

[0061] For structure 2, the one-way valve 12 remains connected to the negative pressure device and is only connected to the sealed battery pack 4 through the front pipe 14 and the rear pipe 15 during the formation stage, so that the one-way valve 12 can be reused. The exhaust structure 1 part that is always connected to the sealed battery pack 4 is the front pipe 14 part of the connecting pipe 11, which has low cost and is easy to separate from the redundant part, which is conducive to the recycling of the redundant part.

[0062] For structure 2, further, the end of the front tube 14 away from the connecting tube 11 is recessed inward to form an interlocking groove 17, and the end of the rear tube 15 away from the one-way valve 12 is interference-fitted with the interlocking groove 17 of the front tube 14, so that the front tube 14 is tightly connected with the rear tube 15. Preferably, the exhaust needle 16 is made of metal material, and one end of the rear tube 15 where the exhaust needle 16 is provided is a hard part, which is convenient for interference-fit connection with the interlocking groove 17.

[0063] The first and second structures of the split exhaust structure 1 are two solutions for the recovery of the one-way valve 12. In the first structure, the one-way valve 12 needs to follow the sealed battery pack 4, and in the second structure, the one-way valve 12 does not need to follow the sealed battery pack 4. Furthermore, the first structure and the second structure can also be combined, that is, the connecting pipe 11 can also be set as a structure of a front pipe 14 and a rear pipe 15, and the rear pipe 15 and the one-way valve 12 adopt a detachable structure. The appropriate exhaust structure 1 can be selected according to the actual situation.

[0064] The embodiments provided by the present invention are described in detail above. Specific examples are used herein to describe the principles and implementation methods of the present invention, and the description of the above embodiments is only used to help understand the core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. An exhaust structure for battery formation, characterized in that: Connected to a sealed battery pack (4) formed by an aluminum-plastic film (3), the exhaust structure (1) comprises: A connecting tube (11) has one end disposed at the edge of the sealed battery pack (4) so ​​that the space inside the sealed battery pack (4) is connected to the connecting tube (11). The one-way valve (12) is located outside the sealed battery pack (4) and is connected to the other end of the connecting tube (11), allowing gas to be discharged from the sealed battery pack (4) and restricting gas from entering the sealed battery pack (4).

2. The exhaust structure for battery formation according to claim 1, characterized in that: A tab rubber layer (13) is provided on the side surface of one end of the connecting tube (11) connected to the sealed battery pack (4), and is fixedly connected to the aluminum-plastic film (3) when the aluminum-plastic film (3) is heat-sealed.

3. The exhaust structure for battery formation according to claim 1, characterized in that: The connecting tube (11) is a plastic part. Preferably, the connecting tube (11) is a plastic part that can withstand the heat-sealing temperature of the aluminum-plastic film (3).

4. The exhaust structure for battery formation according to claim 1, characterized in that: The one-way valve (12) is a plastic part.

5. The exhaust structure for battery formation according to claim 1, characterized in that: The connecting pipe (11) is detachably connected to the one-way valve (12).

6. The exhaust structure for battery formation according to any one of claims 1 to 5, characterized in that: The connecting tube (11) comprises a front tube (14) and a rear tube (15); one end of the front tube (14) is fixedly connected to the sealed battery pack (4); the other end of the front tube (14) away from the sealed battery pack (4) is sealed; the rear tube (15) is connected to the one-way valve (12); an exhaust needle (16) is provided at one end of the rear tube (15) away from the one-way valve (12); the exhaust needle (16) of the rear tube (15) is inserted into the end surface of the front tube (14), so that the front tube (14) and the rear tube (15) are connected.

7. The exhaust structure for battery formation according to claim 6, characterized in that: The end of the front tube (14) away from the connecting tube (11) is recessed inward to form an engaging groove (17), and the end of the rear tube (15) away from the one-way valve (12) is interference-fitted with the engaging groove (17) of the front tube (14), so that the front tube (14) and the rear tube (15) are tightly connected.

8. A system for battery formation, comprising a formation device, characterized in that: It also includes a negative pressure device, which is connected to the exhaust structure for battery formation according to any one of claims 1-7.

9. A chemical formation method, characterized in that: Using the exhaust structure (1) for battery formation according to any one of claims 1 to 7, the formation method comprises: (1) When the aluminum-plastic film (3) is heat-sealed for the first time, one end of the connecting tube (11) of the exhaust structure (1) is heat-sealed and fixed to the edge of the aluminum-plastic film (3) to form a sealed battery pack (4) with the exhaust structure (1), and the connecting tube (11) is away from the battery cell (2) area; (2) placing the sealed battery pack (4) in a formation device, and connecting the exhaust structure (1) to a negative pressure device; (3) forming the battery cell (2) in the sealed battery pack (4), and during the forming process, extracting the gas in the sealed battery pack (4) through the exhaust structure (1) until the forming is completed; (4) performing a second heat seal on the sealed battery pack (4), with the area between the first heat seal and the second heat seal serving as a redundant portion, and the exhaust structure (1) being connected to the redundant portion; (5) The redundant part is cut off to obtain a soft-pack battery product.

10. The chemical formation method according to claim 9, characterized in that: In step (3), after the formation is completed, the portion of the connecting tube (11) outside the sealed battery pack (4) is heat-sealed.

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