Fracture prevention device for use in the rolling process of lithium-ion battery pole pieces

Abstract

A fracture prevention device for use in the rolling process of lithium-ion battery pole pieces is provided. [Solution] The breakage prevention device includes a V-shaped roll 1, a concave-convex roll 2, a floating roll 3, a tension roll 4 and a pinch roll 5 arranged in order on a rack 9 along the transport direction of the pole piece 7, the concave surface of the concave-convex roll corresponds to the coating area of ​​the pole piece, and the convex surface of the concave-convex roll corresponds to the foil material area of ​​the pole piece, and further includes a heating assembly 6 arranged adjacent to the concave-convex roll in front of the concave-convex roll, and the heating end of the heating assembly is located below the foil material area of ​​the pole piece. By adding a heating assembly to heat the foil material area before pulling, the original cold pulling is changed to hot pulling, and the pulling tension can be reduced by 70%, preventing the foil material area from breaking due to the large tension, and ensuring that the pole piece can be continuously wound without breaking.

Description

[Technical field]

[0001] This utility model belongs to the technical field of lithium ion battery production, and specifically relates to a fracture prevention device used in the rolling process of lithium ion battery pole pieces. [Background technology]

[0002] Rolling of the pole pieces is an important step in the production process of lithium-ion batteries. It can strengthen the adhesion strength between the active material and the foil pieces to prevent them from falling off during immersion in the electrolyte and during use of the battery, and can also increase the energy density and power density of the lithium-ion battery and optimize the electrochemical performance.

[0003] The thickness of the coating area of ​​the pole piece is much larger than that of the foil material area, so when the pole piece is rolled, the coating area is stretched by rolling, but the foil material area is not stretched. This causes a problem that there is a difference in the stretch rate between the coating area and the foil material area after the pole piece is rolled. In order to solve the difference in the stretch rate, the current solution in the industry is to cold stretch the foil material area. However, because of the cold stretching, the tension of the pole piece is large, and large tensile stress is generated in the foil material area. In addition, the foil material itself has fine defects such as pinholes and edge cracks during the manufacturing process, so the foil material area is easily broken when it is cold stretched. Summary of the Invention [Problem to be solved by the invention]

[0004] In order to solve the above-mentioned shortcomings in the prior art, the present utility model provides a breakage prevention device for use in the rolling process of lithium ion battery pole pieces, so as to realize continuous winding of the pole pieces while solving the stretching problem of the foil material area of ​​the pole pieces, and further achieve the purpose of improving production efficiency and reducing the waste of the pole pieces. [Means for solving the problem]

[0005] In order to achieve the above object, the technical solution adopted in this utility model is as follows: The breakage prevention device used in the rolling process of lithium ion battery pole pieces according to this utility model includes a V-shaped roll, a concave-convex roll, a floating roll, a tension roll and a pinch roll, which are arranged in order on a rack along the transport direction of the pole pieces, the concave surface of the concave-convex roll corresponds to the coating area of ​​the pole pieces, the convex surface of the concave-convex roll corresponds to the foil material area of ​​the pole pieces, and further includes a heating assembly arranged adjacent to the concave-convex roll before the concave-convex roll, and a heating end of the heating assembly is located below the foil material area of ​​the pole pieces.

[0006] A limitation of the present invention further includes a temperature sensor disposed in correspondence with the foil area of ​​the pole piece.

[0007] As a further limitation of this invention, the heating assembly is mounted to the rack by a three-axis slide table to provide adjustability in three directions: X, Y, and Z.

[0008] As a further limitation of this utility model, the concave-convex roll includes a flat roll and Teflon tape attached to an outer surface of the flat roll to form a convex surface, and a portion of the flat roll to which the Teflon tape is not attached forms a concave surface.

[0009] As a further limitation of the present utility model, it further includes a cooling fan that cools the uneven roll so that the blowing outlet faces the uneven roll.

[0010] As a further limitation of the present invention, the flat roll is provided with internal passages for the circulation of a coolant.

[0011] As another limitation of the present invention, the V-shaped rolls are provided on both sides of the pole piece, one pair for laterally flattening the pole piece. Effect of the Invention

[0012] By adopting the above technical solution, the beneficial effects obtained by this utility model compared with the prior art are as follows: (1) This utility model provides a new means to solve the problem of stretching the foil material area of ​​the pole piece (the problem of the difference in stretch rate between the coating area and the foil material area after rolling the pole piece). Specifically, by adding a heating assembly to heat the foil material area before stretching, the original cold stretching is changed to hot stretching, so that the foil material has a reduced elastic modulus in the hot state and a reduced deformation resistance. At the same time, the thermal expansion of the foil material has already been significantly stretched, so that only a small pulling tension is needed to make the foil material reach the desired stretch rate, and the tension can be reduced by 70% compared with traditional cold stretching. The reduced pulling tension reduces the stress concentration in the foil material area, which can prevent the foil material area from being broken by large tension and reduce the risk of breakage. Regardless of the elongation rate of about 7‰ for normal pole pieces, or the high elongation rate of 15‰ or more for high-pressure dense pole pieces, this utility model can complete all of these, enabling the pole pieces to be wound continuously without breakage, thereby improving production efficiency and significantly reducing pole piece waste. (2) The temperature sensor located in this utility model can monitor the temperature of the foil area in real time, and the temperature feedback can further allow automatic adjustment of the output power by the heating assembly to ensure that the heating temperature required for the process can be met. (3) The heating assembly in this utility model is assembled to the rack via a three-axis sliding table, thereby providing three-way adjustment of X, Y, and Z directions, and can meet different configuration requirements of different processes. (4) The concave-convex roll of the present utility model is the first roll through which the pole piece passes after it leaves the rolling mill, and can prevent wrinkles and breakage of the pole piece when it is wound onto the roll due to the mismatch in the elongation rate between the coating area and the foil material area of ​​the pole piece. The concave-convex roll of the present utility model is configured by attaching Teflon tape to a flat roll, and the amount of the concave-convex can be adjusted according to the needs of the process. Note that the concave-convex roll of the present utility model is a cold roll, and has a cooling function (realized by flowing a refrigerant inside or blowing cold air outside), which can cold fix the elongation of the foil material area after the pole piece enters the concave-convex roll, and further prevents the foil material area from cold shrinking and decreasing the elongation rate after the pole piece leaves the concave-convex roll. By adjusting parameters such as the magnitude of tension, heating temperature, and thickness of the Teflon tape, the stretch rate of the foil area after the pole piece exits the uneven roll can be made equal to or slightly greater than the stretch rate of the coated area. (5) In this utility model, the V-shaped rolls provided on both sides of the pole piece can flatten the pole piece laterally, thereby effectively improving wrinkles in the pole piece. [Brief description of the drawings]

[0013] The present invention will now be described in more detail with reference to the accompanying drawings and specific embodiments. [Figure 1] FIG. 2 is a structural schematic diagram of an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. It should be understood that the preferred embodiments described in this specification are only used to explain and understand the present invention, and do not limit the present invention.

[0015] Example: Fracture prevention device used in the rolling process of lithium-ion battery pole pieces As shown in FIG. 1, this embodiment includes a V-shaped roll 1, a concave-convex roll 2, a floating roll 3, a tension roll 4, and a pinch roll 5 arranged in this order on a rack 9 along the transport direction of the pole piece 7.

[0016] In this embodiment, the V-shaped roll 1, the floating roll 3, the tension roll 4 and the pinch roll 5 are all of existing structures. Here, the V-shaped roll 1 is located at the forefront, and is provided in a pair on both sides of the pole piece 7. Before entering the concave-convex roll 2, the pole piece 7 is first flattened laterally by the V-shaped roll 1, so that the wrinkles of the pole piece 7 can be effectively improved. The floating roll 3 is provided behind the concave-convex roll 2 and is used to adjust the tension around the pole piece 7. The tension roll 4 is provided behind the floating roll 3 and is used to monitor the tension in real time. The pinch roll 5 is provided behind the tension roll 4 and is used to adjust the speed to ensure the stability of the pole piece 7 during transportation.

[0017] The uneven roll 2 is used to prevent the pole piece 7 from breaking when being wound around the roll due to the difference in the elongation rate between the coating area and the foil material area after the pole piece 7 leaves the rolling roll 8. In this embodiment, the uneven roll 2 includes a flat roll and multiple stages of Teflon tape attached to the outer surface of the flat roll. Each stage of Teflon tape runs around the outer surface of the flat roll in the circumferential direction of the flat roll, and the thickness formed by running around can be adjusted according to the needs of the actual process. The multiple stages of Teflon tape are arranged at equal intervals in the axial direction of the flat roll to form the convex surface of the uneven roll 2. The area of ​​the flat roll to which the Teflon tape is not attached forms the concave surface of the uneven roll 2.

[0018] When the pole piece 7 is wound onto the roll, the coating area corresponds to the concave surface of the uneven roll 2 and the foil area corresponds to the convex surface of the uneven roll 2 .

[0019] Furthermore, this embodiment further includes a heating assembly 6 disposed adjacent to the uneven roll 2 provided between the V-shaped roll 1 and the uneven roll 2. The heating assembly 6 employs an existing electromagnetic heating assembly 6 in which an electromagnetic heating coil (i.e., a heating end) is located below the foil material area of ​​the pole piece 7. Note that since the pole piece 7 has a plurality of foil material areas along the lateral direction, a plurality of heating assemblies 6 are usually provided to correspond to the respective foil material areas.

[0020] In this embodiment, the heating assembly 6 is assembled on the rack 9 through a three-axis slide table, so that it has the adjustment function in three directions of X, Y, and Z, and the position of the heating end of the heating assembly 6 can be flexibly adjusted, and the different configuration requirements of different processes can be met. Of course, the heating assembly 6 can also be assembled in other ways to have the adjustment function in three directions of X, Y, and Z. For example, after assembling three guide rails to form a structure that can move in three directions of X, Y, and Z, the position of the slider on the guide rail can be manually adjusted and fixed, or the position of the slider on the guide rail can be adjusted and fixed through a cylinder. The heating assembly 6 is assembled on the guide rail in the Z direction.

[0021] In order to monitor the temperature of the foil area of ​​the pole piece 7, this embodiment also has a temperature sensor arranged on the rack 9 which corresponds to the foil area of ​​the pole piece 7.

[0022] More specifically, the uneven roll 2 in this embodiment is a cold roll, and is used to prevent a decrease in the elongation rate due to cold shrinkage after the pole pieces 7 leave the uneven roll 2. The cold roll can be realized by any of the following methods. One is a method in which an additional air cooler is installed so that its outlet faces the uneven roll 2, and cold air is blown from the outside to give the uneven roll 2 a cooling function. The other is a method in which an internal passage is provided in the flat roll of the uneven roll 2, and a refrigerant is passed through the internal passage to give the uneven roll 2 a cooling function.

[0023] This embodiment can be installed at the entrance or exit of a rolling mill as an independent mechanism, and the center distance between the uneven roll 2 and the rolling roll 8 in the rolling mill is usually within 50 cm. In this embodiment, the installation at the exit of the rolling mill is taken as an example to introduce the usage process. After the pole piece 7 leaves the rolling roll 8, it is first flattened laterally through the V-shaped roll 1, then the foil material area of ​​the pole piece 7 is heated through the heating assembly 6, and the foil material area of ​​the pole piece 7 enters the concave-convex roll 2 in a heated state. After the pole piece 7 enters the concave-convex roller 2, its foil material area corresponds to the convex surface of the concave-convex roller 2, and the coating area corresponds to the concave surface of the concave-convex roller 2, and the foil material area is stretched through the convex surface. After the foil material area of ​​the pole piece 7 is stretched and cold-fixed by the concave-convex roller 2, it passes through the floating roll 3, tension roll 4, and pinch roll 5 in that order, and is finally wound up.

[0024] It should be noted that the above are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the above embodiments, those skilled in the art may modify the technical solutions described in the above embodiments or equivalently replace some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model. [Explanation of symbols]

[0025] 1. U-shaped roll, 2. uneven roll, 3. floating roll, 4. tension roll, 5. pinch roll, 6. heating assembly, 7. pole piece, 8. rolling roll, 9. rack.

Claims

1. The apparatus includes a V-shaped roll, a concave-convex roll, a floating roll, a tension roll, and a pinch roll, which are arranged in order on a rack along the transport direction of the pole pieces, The concave surface of the concave roll corresponds to a coating area of ​​the pole piece, and the convex surface of the concave roll corresponds to a foil material area of ​​the pole piece; further comprising a heating assembly disposed adjacent to the uneven roll prior to the uneven roll; a heating end of the heating assembly located below the foil area of ​​the pole piece; A breakage prevention device used in the rolling process of lithium ion battery pole pieces, characterized in that

2. Further comprising a temperature sensor provided corresponding to the foil material area of ​​the pole piece.

2. The breakage prevention device for use in the rolling process of lithium ion battery pole pieces according to claim 1.

3. The heating assembly is mounted to the rack by a three-axis slide table to provide adjustment in three directions: X, Y, and Z.

2. The breakage prevention device for use in the rolling process of lithium ion battery pole pieces according to claim 1.

4. The uneven roll includes a flat roll and a Teflon tape attached to an outer surface of the flat roll so as to form a convex surface; A portion of the flat roll to which the Teflon tape is not applied forms a concave surface. The breakage prevention device for use in the rolling process of lithium ion battery pole pieces according to claim 3.

5. Further comprising a cooling fan for cooling the uneven roll so that the blowing port faces the uneven roll; The breakage prevention device for use in the rolling process of lithium ion battery pole pieces according to claim 4.

6. The flat roll is provided with internal passages for the circulation of the coolant. The breakage prevention device for use in the rolling process of lithium ion battery pole pieces according to claim 4.

7. A pair of V-shaped rolls are provided on each side of the pole piece to flatten the pole piece laterally. A fracture prevention device for use in a rolling process of a lithium ion battery electrode piece according to any one of claims 1 to 6.

Images