Formation device

Abstract

The utility model provides a formation device, and relates to the technical field of battery production. The formation device comprises a base and at least two clamping plates arranged on the base, a battery cell is placed between every two adjacent clamping plates, two opposite plate surfaces of every two adjacent clamping plates are used for directly facing two large surfaces of the battery cell respectively, and buffer material layers are arranged on the two opposite plate surfaces of every two adjacent clamping plates. The buffer material layer is used for being attached to the large surface of the battery cell, the elastic modulus of the buffer material layer is 0.001-0.6 GPa, and the buffer material layer can reduce the restraining force on the battery cell to a certain extent.

Description

Technical Field

[0001] The present application relates to the technical field of battery production, and in particular to a formation device. Background Art

[0002] The gaps in the commonly used formation fixtures are large, and there is no clear limit on the expansion of the battery cells. During the formation and gas production process of lithium-supplemented batteries, the battery cells have a large space for expansion, and gas is easily retained between the electrodes, resulting in poor battery cell thickness and black spots on the interface.

[0003] To help gas discharge, a certain amount of pressure can be applied to the large surface of the cell by the clamp during the constrained formation process to maintain smooth contact between the pole pieces, limit excessive expansion of the cell, help control the consistency of the cell thickness, and help avoid interface defects such as black spots. However, during the full charge process of the lithium-supplemented cell, as the charging SOC increases, the thickness of the cell will gradually increase, and the pressure (constraint force) of the clamp on the large surface of the cell will also increase accordingly. Under the restraint of excessive restraint, the gap between the pole pieces is compressed, and the electrolyte storage space is reduced, which will eventually lead to insufficient pole piece infiltration and lithium deposition on the large surface of the cell. Utility Model Content

[0004] The purpose of the present application includes, for example, providing a formation device that can reduce the restraining force on the battery cell to a certain extent.

[0005] The embodiments of the present application can be implemented as follows:

[0006] An embodiment of the present application provides a formation device, which includes a base and at least two clamps arranged on the base, wherein the space between two adjacent clamps is used to place battery cells, and the two opposite plate surfaces of the two adjacent clamps are respectively used to face the two large surfaces of the battery cells, and a buffer material layer is provided on the two opposite plate surfaces of the two adjacent clamps, and the buffer material layer is used to fit with the large surface of the battery cell, and the elastic modulus of the buffer material layer is 0.001-0.6GPa.

[0007] Optionally, the buffer material layer is made of one of polytetrafluoroethylene, polyethylene foam, polypropylene foam, silicone pad, and polyurethane foam.

[0008] Optionally, the elastic modulus of the buffer material layer made of polytetrafluoroethylene is 0.4-0.6 GPa;

[0009] The elastic modulus of the buffer material layer made of polyethylene foam is 0.01-0.1 GPa;

[0010] The elastic modulus of the buffer material layer made of polypropylene foam is 0.02-0.1 GPa;

[0011] The elastic modulus of the buffer material layer made of silicone pad is 0.001-0.01 GPa;

[0012] The elastic modulus of the buffer material layer made of polyurethane foam is 0.02-0.08 GPa.

[0013] Optionally, the buffer material layer is made of 15-fold expanded polypropylene foam, and the thickness of the buffer material layer is 0.2-0.4 mm; or, the buffer material layer is made of 10-fold expanded polypropylene foam, and the thickness of the buffer material layer is 0.4-0.6 mm.

[0014] Optionally, the buffer material layer is made of a silicone pad, and the thickness of the buffer material layer is 0.8-1.2 mm.

[0015] Optionally, the thickness of the buffer material layer is 0.1-10 mm.

[0016] Optionally, the formation device further comprises a driving mechanism, which is disposed on the base and connected to at least one of the splints to drive the splint to move toward or away from another adjacent splint.

[0017] Optionally, a slide groove is provided on the base, and the extension direction of the slide groove is consistent with the connection direction of the two adjacent clamps. A slider is provided on the clamp connected to the driving mechanism, and the slider is slidably engaged with the slide groove.

[0018] Optionally, a limit block is provided in the slide groove, and the limit block is located between two adjacent clamping plates and is used to limit the distance between the two adjacent clamping plates.

[0019] Optionally, the driving mechanism includes a screw, which is rotatably disposed on the base and engages with a thread of at least one of the clamping plates to drive the clamping plate to move toward another adjacent clamping plate.

[0020] The beneficial effects of the formation device provided by the embodiments of the present application include, for example: in order to reduce the restraining force on the battery cell to a certain extent, a formation device is designed, which includes a base and at least two clamps arranged on the base, the battery cell is placed between two adjacent clamps, the two opposite plate surfaces of the two adjacent clamps are respectively used to face the two large surfaces of the battery cell, and a buffer material layer is provided on the two opposite plate surfaces of the two adjacent clamps, the buffer material layer is used to fit with the large surface of the battery cell, and the elastic modulus of the buffer material layer is 0.001-0.6GPa. During the battery cell formation process, the battery cell is placed between two adjacent clamps, and the buffer material layers provided on the two clamps are both in contact with the large surface of the battery cell. The expansion of the battery cell squeezes the buffer material layers on both sides thereof. By limiting the elastic modulus of the buffer material layer to 0.001-0.6GPa, the buffer material layer with an elastic modulus within the range of 0.001-0.6GPa can absorb part of the squeezing force of the clamps to a certain extent. When the battery cell is restrained at all times, the restraining force on the battery cell is reduced to avoid the occurrence of lithium deposition on a large surface of the battery cell due to excessive restraining force. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 This is a schematic diagram of a formation device in an embodiment of the present application;

[0023] Figure 2 Schematic diagram of the overcharge constraint force curve in the embodiment of the present application.

[0024] Icon: 1-base; 2-plywood; 21-buffer material layer; 3-battery cell. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0027] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0028] In the description of this application, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the utility model product is usually placed when in use. It is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on this application.

[0029] In addition, the terms "first", "second", etc., if used, are merely used to distinguish and describe, and should not be understood as indicating or implying relative importance.

[0030] It should be noted that, in the absence of conflict, the features in the embodiments of this application can be combined with each other.

[0031] The inventors of this application discovered that during the formation and full charge process of a lithium-supplemented battery cell, as the charging SOC increases, the thickness of the battery cell gradually increases. At this time, the pressure (restraint) of the clamp on the large surface of the battery cell also increases accordingly. Under excessive restraint, the gap between the electrode pieces is compressed, and the electrolyte storage space is reduced, which ultimately leads to insufficient electrode wetting and lithium deposition on the large surface of the battery cell. The embodiments of this application provide a formation device that is at least used to solve this technical problem.

[0032] Please refer to Figure 1 The formation device provided in the embodiment of the present application includes a base 1 and at least two plywoods 2 arranged on the base 1, and the battery cell 3 is placed between the two adjacent plywoods 2. The two opposite plate surfaces of the two adjacent plywoods 2 are respectively used to face the two large surfaces of the battery cell 3. A buffer material layer 21 is provided on the two opposite plate surfaces of the two adjacent plywoods 2. The buffer material layer 21 is used to fit with the large surface of the battery cell 3, and the elastic modulus of the buffer material layer 21 is 0.001-0.6GPa.

[0033] It should be pointed out that the spacing between two adjacent plywood plates 2 matches the thickness of the battery cell 3. The thickness of the battery cell 3 is the distance between the two large surfaces of the battery cell 3. One battery cell 3 is placed between any two adjacent plywood plates 2. The two buffer material layers 21 arranged on the two opposite surfaces of the two adjacent plywood plates 2 are respectively bonded to the two large surfaces of the battery cell 3, and the area of ​​the buffer material layer 21 covers the large surface area of ​​the battery cell 3.

[0034] The number of splints 2 can be determined according to actual working conditions. For example, five splints 2 are provided on the base 1, and a battery cell 3 is placed between two adjacent splints 2. The two large surfaces of the battery cell 3 are respectively attached to the two buffer material layers 21 on the two adjacent splints 2.

[0035] During the process of fully charging the battery cell 3, the battery cell 3 expands and squeezes the buffer material layer 21. According to Hooke's law, the force exerted by the buffer material layer 21 on the battery cell 3, that is, the restraint force, satisfies: F = -k*Δx, where k is the elastic modulus of the material and Δx is the extrusion deformation of the buffer material layer 21.

[0036] During the formation process, a single battery cell 3 is placed between two adjacent plywood plates 2, and the buffer material layers 21 provided on the two plywood plates 2 are both in contact with the two large surfaces of the battery cell 3. When the battery cell 3 expands, the buffer material layers 21 on both sides thereof are squeezed. By limiting the elastic modulus of the buffer material layer 21 to 0.001-0.6GPa, the buffer material layer 21 with an elastic modulus within the range of 0.001-0.6GPa can absorb part of the squeezing force of the plywood plates 2 to a certain extent. When the battery cell 3 is restrained at all times, the restraining force on the battery cell 3 is reduced to avoid the occurrence of lithium deposition on a large surface of the battery cell 3 due to excessive restraining force.

[0037] In some embodiments, the buffer material layer 21 is made of one of polytetrafluoroethylene, polyethylene foam, polypropylene foam, silicone pad, and polyurethane foam.

[0038] Selecting materials with different elastic moduli produces different restraining forces on the battery cell 3 under the same extrusion deformation. Suitable materials can be selected for the buffer material layer 21 based on the gas generation and thickness expansion characteristics of the lithium-supplemented battery cell 3. In this embodiment, the buffer material layer 21 is made of one of polytetrafluoroethylene, polyethylene foam, polypropylene foam, silicone pad, and polyurethane foam. The elastic modulus of the buffer material layer 21 is within the range of 0.001-0.6 GPa, which can absorb some of the extrusion force of the clamping plate 2 to a certain extent, thereby reducing the restraining force on the battery cell 3 when the battery cell 3 is constantly restrained.

[0039] The elastic modulus of the buffer material layer 21 made of polytetrafluoroethylene is 0.4-0.6GPa; the elastic modulus of the buffer material layer 21 made of polyethylene foam is 0.01-0.1GPa; the elastic modulus of the buffer material layer 21 made of polypropylene foam is 0.02-0.1GPa; the elastic modulus of the buffer material layer 21 made of silicone pad is 0.001-0.01GPa; the elastic modulus of the buffer material layer 21 made of polyurethane foam is 0.02-0.08GPa.

[0040] Illustratively, the elastic modulus of the buffer material layer 21 made of polytetrafluoroethylene is 0.4 GPa, 0.5 GPa or 0.6 GPa; the elastic modulus of the buffer material layer 21 made of polyethylene foam is 0.01 GPa, 0.05 GPa, 0.08 GPa or 0.1 GPa; the elastic modulus of the buffer material layer 21 made of polypropylene foam is 0.02 GPa, 0.05 GPa, 0.08 GPa or 0.1 GPa; the elastic modulus of the buffer material layer 21 made of silicone pad is 0.001 GPa, 0.005 GPa, 0.008 GPa or 0.01 GPa; the elastic modulus of the buffer material layer 21 made of polyurethane foam is 0.02 GPa, 0.05 GPa or 0.08 GPa.

[0041] It is understandable that the elastic modulus of the buffer material layer 21 made of one of polytetrafluoroethylene, polyethylene foam, polypropylene foam, silicone pad, and polyurethane foam can be selected within the above range according to actual working conditions.

[0042] Figure 2 A formation overcharge restraint force curve is shown, where the horizontal axis is the charging SOC and the vertical axis is the restraint force on the battery cell 3. No buffer material refers to direct contact with the battery cell through the splint. Buffer material A is polytetrafluoroethylene, buffer material B is polyethylene foam, and buffer material C is a silicone pad. At the same charging SOC, the restraint force of no buffer material, buffer material A, buffer material B and buffer material C on the battery cell 3 decreases in turn.

[0043] In some embodiments, the thickness of the buffer material layer 21 is 0.1-10 mm.

[0044] The thickness direction of the buffer material layer 21 is consistent with the connecting direction of the two adjacent splints 2. According to the actual working conditions, the thickness of the buffer material layer 21 can be selected within the range of 0.1-10mm. For example, the thickness of the buffer material layer 21 is 0.1mm, 0.5mm, 1mm, 3mm, 5mm, 8mm or 10mm.

[0045] In some embodiments, the formation device further includes a driving mechanism, which is disposed on the base 1 and connected to at least one splint 2 to drive the splint 2 to move toward or away from another adjacent splint 2 .

[0046] It should be noted that, for two adjacent splints 2, the driving mechanism can be connected to one of the splints 2 to drive the splint 2 to move toward or away from the other adjacent splint 2, or, the driving mechanism can be connected to two adjacent splints 2 at the same time to drive the two adjacent splints 2 to move toward or away from each other. As long as the spacing between the two adjacent splints 2 is adjusted to match the thickness of the battery cell 3, the convenience of operating the formation device is improved.

[0047] In some embodiments, a slide groove is provided on the base 1, and the extension direction of the slide groove is consistent with the connection direction of two adjacent splints 2. A slider is provided on the splint 2 connected to the driving mechanism, and the slider slides in cooperation with the slide groove.

[0048] By providing a sliding groove on the base 1 and arranging a slider on the splint 2, the slider and the sliding groove slide together, so that the movement process of the splint 2 relative to the base 1 can be made more stable.

[0049] Furthermore, a limit block is provided in the slide groove, and the limit block is located between two adjacent clamping plates 2 and is used to limit the distance between the two adjacent clamping plates 2.

[0050] For two adjacent splints 2, if the driving mechanism is only connected to one of the splints 2 to drive the splint 2 to move toward or away from the other adjacent splint 2, the other splint 2 is fixed to the base 1. When the splint 2 moves toward the other splint 2 until the slider abuts the limit block, the distance between the two adjacent splints 2 is fixed, which plays the role of a fixed gap. At this time, the two buffer material layers 21 on the two adjacent splints 2 just fit the two large surfaces of the battery cell 3.

[0051] If the driving mechanism is connected to two adjacent splints 2 at the same time to drive the two adjacent splints 2 to move toward or away from each other, two limit blocks are correspondingly provided in the slide groove. When the two splints 2 move toward each other until the two sliders respectively abut against the two limit blocks, the distance between the two adjacent splints 2 is fixed, which plays the role of a fixed gap. At this time, the two buffer material layers 21 on the two adjacent splints 2 just fit the two large surfaces of the battery cell 3.

[0052] In other embodiments, a slide rail is provided on the base 1, and a slide groove is provided on the splint 2 connected to the driving mechanism. The slide groove on each splint 2 slides with the slide rail, which can also make the movement process of the splint 2 relative to the base 1 more stable.

[0053] In some embodiments, the driving mechanism includes a screw, which is rotatably disposed on the base 1 and threadably engaged with at least one clamping plate 2 to drive the clamping plate 2 to move toward another adjacent clamping plate 2 .

[0054] The screw extends in the same direction as the line connecting the two adjacent splints 2. The screw can be rotated manually or driven by a motor, without limitation. The number of screws can be determined based on the actual working conditions, as long as it can cause one of the two adjacent splints 2 to move toward or away from the other splint 2, or the two splints 2 to move toward or away from each other. When the screw drives the two splints 2 to move toward or away from each other, the screw can be a bidirectional screw.

[0055] The following is further described with reference to Examples and Comparative Examples:

[0056] Example 1:

[0057] The buffer material layer 21 is made of 15 times expanded polypropylene foam, and the thickness of the buffer material layer 21 is 0.2-0.4 mm, wherein the thickness of the buffer material layer 21 can be selected to be 0.3 mm. The screw drives the splint 2 to move so that the two buffer material layers 21 on the two adjacent splints 2 are bonded to the two large surfaces of the battery core 3.

[0058] Example 2:

[0059] The buffer material layer 21 is made of 10 times expanded polypropylene foam, and the thickness of the buffer material layer 21 is 0.4-0.6 mm, wherein the thickness of the buffer material layer 21 can be selected to be 0.5 mm. The screw drives the splint 2 to move so that the two buffer material layers 21 on the two adjacent splints 2 are bonded to the two large surfaces of the battery core 3.

[0060] Example 3:

[0061] The buffer material layer 21 is made of a silicone pad, and the thickness of the buffer material layer 21 is 0.8-1.2 mm. The thickness of the buffer material layer 21 can be optionally 1 mm. The screw drives the splint 2 to move so that the two buffer material layers 21 on the two adjacent splints 2 fit with the two large surfaces of the battery cell 3.

[0062] Comparative Example 1:

[0063] A conventional formation fixture is used, and no clamping plates 2 are set on both sides of the battery cell 3. A plurality of placement slots for placing the battery cells 3 are set in the fixture. When the battery cells 3 are placed in the placement slots, there is a gap between the large surface of the battery cells 3 and the inner wall of the placement slot. The gap between two adjacent battery cells 3 is about 10 mm.

[0064] Comparative Example 2:

[0065] No buffer material layer 21 is provided on the clamping plates 2 , and the battery cell 3 is directly clamped by two adjacent clamping plates 2 , and the clamping plates 2 are driven to move by screws so that the plate surfaces of the two adjacent clamping plates 2 are directly in contact with the two large surfaces of the battery cell 3 .

[0066] By respectively implementing the above embodiments and comparative examples, embodiments 1-3 all adopt fixed-gap constrained formation, and a buffer material layer 21 is provided on the plate surface of the clamping plate 2 facing the battery cell 3. During the formation and full charge expansion of the lithium-supplemented battery cell 3, the elastic properties of the buffer material layer 21 are utilized to absorb part of the squeezing force of the clamping plate 2. On the one hand, the large surface of the battery cell 3 is kept in a constrained state at all times, which can help to discharge the gas generated during the formation process. On the other hand, excessive restraint force is avoided, which improves lithium deposition on the large surface of the battery cell 3. In addition, by selecting different buffer materials, the restraint force during the formation process can be adjusted, which can adapt to material systems with different lithium supplement agent addition amounts and different expansion coefficients.

[0067] Compared with Examples 1-3, the conventional formation fixture used in Comparative Example 1 has no restraining force on the battery cell 3, resulting in the battery cell 3 being unable to smoothly discharge the gas generated during the formation process. In Comparative Example 2, directly bonding the splint 2 to the large surface of the battery cell 3 will cause excessive restraining force, thereby causing lithium deposition on the large surface of the battery cell 3.

[0068] In summary, the embodiment of the present application provides a formation device. During the formation process of the battery cell 3, a single battery cell 3 is placed between two adjacent plywood 2, and the buffer material layers 21 provided on the two plywood 2 are both in contact with the two large surfaces of the battery cell 3. When the battery cell 3 expands, the buffer material layers 21 on both sides thereof are squeezed. By limiting the elastic modulus of the buffer material layer 21 to a certain range, the buffer material layer 21 can absorb part of the squeezing force of the plywood 2 to a certain extent. When the battery cell 3 is restrained at all times, the restraining force on the battery cell 3 is reduced to avoid the occurrence of lithium deposition on the large surface of the battery cell 3 due to excessive restraining force.

[0069] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A chemical formation device, characterized in that: It includes a base and at least two clamps arranged on the base, the space between two adjacent clamps is used to place battery cells, the two opposite plate surfaces of the two adjacent clamps are respectively used to face the two large surfaces of the battery cells, and a buffer material layer is provided on the two opposite plate surfaces of the two adjacent clamps, the buffer material layer is used to fit with the large surface of the battery cell, and the elastic modulus of the buffer material layer is 0.001-0.6GPa.

2. The chemical formation device according to claim 1, characterized in that The buffer material layer is made of one of polytetrafluoroethylene, polyethylene foam, polypropylene foam, silicone pad, and polyurethane foam.

3. The chemical formation device according to claim 2, characterized in that The elastic modulus of the buffer material layer made of polytetrafluoroethylene is 0.4-0.6 GPa; The elastic modulus of the buffer material layer made of polyethylene foam is 0.01-0.1 GPa; The elastic modulus of the buffer material layer made of polypropylene foam is 0.02-0.1 GPa; The elastic modulus of the buffer material layer made of silicone pad is 0.001-0.01 GPa; The elastic modulus of the buffer material layer made of polyurethane foam is 0.02-0.08 GPa.

4. The chemical formation device according to claim 2, characterized in that The buffer material layer is made of 15-fold expanded polypropylene foam, and the thickness of the buffer material layer is 0.2-0.4 mm; or, the buffer material layer is made of 10-fold expanded polypropylene foam, and the thickness of the buffer material layer is 0.4-0.6 mm.

5. The chemical formation device according to claim 2, characterized in that The buffer material layer is made of a silica gel pad, and the thickness of the buffer material layer is 0.8-1.2 mm.

6. The chemical formation device according to claim 1, characterized in that The thickness of the buffer material layer is 0.1-10 mm.

7. The chemical formation device according to claim 1, characterized in that The formation device further includes a driving mechanism, which is disposed on the base and connected to at least one of the clamping plates to drive the clamping plate to move toward or away from another adjacent clamping plate.

8. The chemical formation device according to claim 7, characterized in that A sliding groove is provided on the base, and the extending direction of the sliding groove is consistent with the connecting direction of two adjacent clamping plates. A sliding block is provided on the clamping plate connected to the driving mechanism, and the sliding block is slidably matched with the sliding groove.

9. The chemical formation device according to claim 8, characterized in that: A limiting block is provided in the slide groove, and the limiting block is located between two adjacent clamping plates and is used to limit the distance between the two adjacent clamping plates.

10. The chemical formation device according to claim 7, characterized in that: The driving mechanism includes a screw rod, which is rotatably disposed on the base and is threadably engaged with at least one of the clamping plates to drive the clamping plate to move toward another adjacent clamping plate.

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