Diaphragm with positioning mark and secondary battery

Abstract

The utility model provides a diaphragm with a positioning mark and a secondary battery, and belongs to the technical field of secondary batteries. According to the diaphragm with the positioning mark, the carbon black positioning mark is arranged on the surface of at least one side of the diaphragm, the diaphragm with the positioning mark is provided with the carbon black positioning mark, and the carbon black positioning mark can be used for positioning the residual amount of the diaphragm when a battery cell is prepared, so that the optimal rate of an assembly process of a secondary battery is improved; the diaphragm waste during roll replacement is reduced, the effects of reducing cost and improving efficiency are achieved, and the carbon black positioning marks do not cause negative effects on the battery performance and can stably exist in the battery.

Description

Technical Field

[0001] The utility model belongs to the technical field of secondary batteries, and in particular relates to a diaphragm with positioning marks and a secondary battery. Background Art

[0002] Currently, the production capacity of secondary batteries is constantly expanding, and the manufacturing cost is constantly decreasing. The production speed is also required to be accelerated and the utilization rate of raw materials needs to be increased as much as possible. Therefore, continuous improvements are needed in the secondary battery manufacturing process to match the rapid production needs.

[0003] The secondary battery assembly process is a key point that restricts the rapid preparation of batteries. Among them, the identification of the remaining amount of diaphragms and the replacement of diaphragm rolls during the preparation of battery cells are time-consuming and wasteful links in the preparation process. The current industry usually uses distance recognition devices or operator experience to judge the remaining amount of diaphragms. Due to differences in the support rolls of the diaphragms and the diaphragm winding tension, the remaining amount is difficult to accurately identify, which often results in insufficient diaphragms during the use of battery cells, resulting in unqualified battery cells being scrapped, or replacing the rolls when there is still a lot of diaphragms remaining to ensure that fewer battery cells are scrapped, thereby increasing production costs.

[0004] Some secondary battery manufacturers have observed this demand and use colored pigments to mark the diaphragms for differentiation. However, the colored pigment marked part may be rolled into the battery cell, and the colored pigment will dissolve in the electrolyte after injection, thus significantly affecting the battery performance. Therefore, setting an identifiable mark on the diaphragm end that will not affect the battery performance for remaining quantity and roll replacement warnings has positive significance for the rapid and low-cost manufacturing of battery cells. Utility Model Content

[0005] The utility model aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the embodiment of the utility model provides a diaphragm with a positioning mark and a secondary battery.

[0006] The utility model provides a diaphragm with a positioning mark, wherein a carbon black positioning mark is arranged on at least one side surface of the diaphragm.

[0007] The advantages and technical effects brought by the diaphragm of the utility model are:

[0008] (1) The diaphragm of the utility model has a carbon black positioning mark, which can be used to locate the remaining amount of the diaphragm during the preparation of the battery cell, thereby improving the efficiency of the secondary battery assembly process, reducing the waste of the diaphragm during the roll change, and playing a role in reducing costs and increasing efficiency.

[0009] (2) The diaphragm of the utility model has a carbon black positioning mark, which will not have a negative impact on battery performance and can exist stably in the battery.

[0010] In some embodiments, the distance between the carbon black positioning mark and the tail of the separator is L1, the length of the separator on one side of the battery cell is L2, and L2 ≤ L1 ≤ 1.5L2. Preferably, L2 ≤ L1 ≤ 1.1L2. More preferably, L1 = L2.

[0011] In some embodiments, the distance between the positioning carbon black mark and the tail of the separator is L1, the length of the separator on one side of the battery cell is L2, and 0 < L1 < 0.5L2. Preferably, 0 < L1 < 0.1L2.

[0012] In some embodiments, the shape of the carbon black positioning mark is at least one of a rectangle, a square, a triangle, and a circle.

[0013] In some embodiments, the area of the carbon black positioning mark is 0.5 - 100 square millimeters.

[0014] In some embodiments, the entire carbon black positioning mark is black, or only the outline of the carbon black positioning mark is black.

[0015] In some embodiments, the carbon black positioning mark is disposed at a position close to the edge of the separator in the width direction of the separator.

[0016] A secondary battery, characterized in that the battery cell of the secondary battery includes the separator of the present invention. In addition, the present invention also provides a secondary battery, and the battery cell of this secondary battery includes the separator of the present invention.

[0017] The advantages and technical effects brought by the secondary battery of the present invention are as follows:

[0018] Due to the use of the separator with a positioning mark of the present invention, the production costs of the battery cell and the secondary battery are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of the separator according to Embodiment 1 of the present invention;

[0020] Figure 2 is a schematic structural diagram of the separator according to Embodiment 6 of the present invention;

[0021] Figure 3 is a schematic structural diagram of the separator according to Embodiment 10 of the present invention.

[0022] Description of the reference numerals: 1 - separator; 101 - separator base film; 102 - separator coating; 2 - carbon black positioning mark. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] Embodiments of the present utility model will be described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present utility model and should not be construed as a limitation to the present utility model.

[0024] The present utility model provides a diaphragm with positioning marks, as Figures 1-3 shown, carbon black positioning marks 2 are provided on at least one side surface of the diaphragm 1.

[0025] The diaphragm of the present utility model has carbon black positioning marks. Since the diaphragm is generally white and the carbon black positioning marks are black, there is an obvious color difference between the two. Therefore, the carbon black positioning marks can be used for remaining amount and roll change warning. Moreover, since carbon black is contained in the battery electrode sheet itself, the carbon black positioning marks will not have a negative impact on the battery performance and can stably exist in the battery.

[0026] It should be noted that a visual recognition instrument can be used to recognize the carbon black positioning marks, or the positioning marks can be recognized by manual observation.

[0027] In some embodiments, the distance between the carbon black positioning mark and the tail of the diaphragm is L1, and the length of the single-sided diaphragm of the battery cell is L2, where L2 ≤ L1 ≤ 1.5L2. For example, L1 is equal to L2, 1.01L2, 1.05L2, 1.1L2, 1.2L2, 1.3L2, 1.4L2, 1.5L2, etc. When the carbon black positioning mark is detected, the remaining diaphragm amount can meet the usage amount of the single-sided diaphragm of one battery cell. Therefore, after the carbon black positioning mark is recognized, the roll change operation can be performed after the battery cell is prepared. Preferably, L2 ≤ L1 ≤ 1.1L2. The purpose of this setting is to perform roll change when there is less remaining diaphragm, thereby reducing the production cost. More preferably, L1 = L2. This is the most ideal situation, which can maximize the reduction of the production cost of the battery cell.

[0028] In some embodiments, the distance between the carbon black positioning mark and the tail of the diaphragm is L1, and the length of the single-sided diaphragm of the battery cell is L2, where 0 < L1 < 0.5L2. For example, L1 is equal to 0.01L2, 0.05L2, 0.1L2, 0.2L2, 0.3L2, 0.4L2, 0.5L2, etc. In this case, when the carbon black positioning mark is detected, the remaining diaphragm amount is not enough to meet the usage amount of the single-sided diaphragm of one battery cell. Therefore, after the carbon black positioning mark is recognized, the roll change operation needs to be performed immediately by stopping the preparation of the battery cell. Preferably, 0 < L1 < 0.1L2. The purpose of this setting is to perform roll change when there is less remaining diaphragm, thereby reducing the production cost.

[0029] The shape of the carbon black positioning mark on the diaphragm of the present utility model is not particularly limited and can be any shape. For example, the shape of the carbon black positioning mark can be at least one of a rectangle, a square, a triangle, and a circle, or can also be other irregular shapes. The carbon black positioning mark can be entirely covered with a carbon black-containing material to form a positioning mark filled with a black color block as shown in Figures 1-2 ; or it can also be that only the outline of the positioning mark is outlined with a carbon black-containing material to form a carbon black positioning mark with a black outline as shown in Figure 3 .

[0030] The size of the carbon black positioning mark on the diaphragm of the present utility model is not particularly limited, as long as it can be monitored by a visual recognition instrument or observed manually. For example, the area of the carbon black positioning mark can be 0.5 - 100 square millimeters, such as 0.5 square millimeters, 1 square millimeter, 5 square millimeters, 10 square millimeters, 20 square millimeters, 30 square millimeters, 40 square millimeters, 50 square millimeters, 60 square millimeters, 70 square millimeters, 80 square millimeters, 90 square millimeters, 100 square millimeters, etc. It can be understood that on the basis that the carbon black positioning mark can be recognized, the smaller the area of the carbon black positioning mark, the better. For example, when using a visual recognition instrument to monitor the carbon black positioning mark, since the accuracy and automation degree are relatively high, a carbon black positioning mark with a smaller area can be set. And if manual observation is used to monitor the carbon black positioning mark, a carbon black positioning mark with a larger area can be selected to avoid missing it during manual observation.

[0031] In the diaphragm of the present utility model, the number of carbon black positioning marks provided on one side of the diaphragm is at least 1, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. It can be understood that on the basis that the carbon black positioning mark can be recognized, the fewer the number of carbon black positioning marks, the better. For example, when using a visual recognition instrument to monitor the carbon black positioning mark, since the accuracy and automation degree are relatively high, setting 1 carbon black positioning mark is sufficient. And if manual observation is used to monitor the carbon black positioning mark, several more carbon black positioning marks can be selected to avoid missing it during manual observation.

[0032] In some embodiments, the carbon black positioning mark is provided at a position close to the edge of the diaphragm in the width direction of the diaphragm. In this case, it is beneficial for the visual recognition instrument or manual observation to recognize the carbon black positioning mark.

[0033] The structure of the diaphragm of the present utility model is not particularly limited. For example, it can only have a diaphragm base film 101, or as shown in Figure 1 , it includes a diaphragm base film 101 and a diaphragm coating 102.

[0034] In addition, the present utility model also provides a method for preparing a diaphragm with positioning marks, comprising the following steps:

[0035] S1. Diaphragm preparation: Prepare the diaphragm according to production requirements;

[0036] S2. Preparation of carbon black marking slurry: Mix carbon black, binder and solvent according to the designed ratio to form a uniform and stable carbon black positioning marking slurry, and load the carbon black positioning marking slurry into the marking brushing equipment;

[0037] S3. Diaphragm slitting: Slit the diaphragm according to the required specifications (diaphragm width) of the diaphragm and wind it into small rolls, and at the same time start length measurement;

[0038] S4. Brushing of carbon black positioning marking slurry: Brush the carbon black positioning marking slurry on the diaphragm at a position with a length of L1 from the tail of the diaphragm according to the requirements of the diaphragm user;

[0039] S5. Curing and drying: After drying the diaphragm brushed with the carbon black positioning marking slurry, a diaphragm with carbon black positioning marks is obtained.

[0040] This preparation method transfers the carbon black positioning marking slurry from being brushed on the set position of the diaphragm to the diaphragm, and then the carbon black positioning marks are fixed on the surface of the diaphragm through drying. This method is simple and easy to operate and is suitable for industrial production.

[0041] This preparation method can simply obtain a diaphragm with carbon black positioning marks, which is used for positioning during use, improves the excellent rate of the secondary battery assembly process, reduces the waste of the diaphragm during roll change, and plays a role in cost reduction and efficiency improvement;

[0042] This preparation method innovatively uses carbon black positioning marking slurry as the marking raw material. Because carbon black is contained in the electrode sheet itself and the carbon black particles are generally small, even if it is dispersed into the electrolyte during the subsequent use of the battery cell, it will not have a negative impact on the battery performance and can stably exist in the battery. At the same time, the preparation and use of the slurry are simple and the cost is low.

[0043] There is no particular limitation on the type of diaphragm used in step S1 of this preparation method. In some embodiments, in step S1, the diaphragm may include a diaphragm base film and optionally a diaphragm coating. The diaphragm base film may be at least one of a polyolefin film, an aramid film, a polyimide film and a non-woven film; the functional particles contained in the diaphragm coating may be at least one of PVDF particles, ceramic particles, boehmite, polymethyl methacrylate (PMMA) or the particles used for the surface coating of the base film in the prior art.

[0044] In step S2 of the preparation method, the carbon black positioning and marking slurry includes carbon black, a binder, and a solvent. Additionally, the carbon black positioning and marking slurry may further include a dispersant and / or a stabilizer. In some embodiments, the carbon black positioning and marking slurry may include the following components: 0.1 - 10 parts by weight of carbon black, 0.1 - 2 parts by weight of binder, 0 - 2 parts by weight of dispersant, 0 - 2 parts by weight of stabilizer, and 85 - 99 parts by weight of solvent.

[0045] In some embodiments, the carbon black used in the carbon black positioning and marking slurry in step S2 may include at least one of pigment carbon black, rubber carbon black, reinforcing carbon black, conductive carbon black, and wear-resistant carbon black, preferably battery-grade conductive carbon black.

[0046] In some embodiments, the binder used in the carbon black positioning and marking slurry in step S2 may include at least one of polyacrylates, polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), nitrile rubber, and natural rubber, preferably polyacrylates.

[0047] In some embodiments, the dispersant used in the carbon black positioning and marking slurry in step S2 may include at least one of polymeric dispersants, non-ionic dispersants, anionic wetting dispersants, electro-neutral wetting dispersants, and surfactant-based dispersants.

[0048] In some embodiments, the stabilizer used in the carbon black positioning and marking slurry in step S2 may include at least one of carboxymethyl cellulose-based, polyacrylamide-based, and polyvinyl alcohol.

[0049] In some embodiments, the solvent used in the carbon black positioning and marking slurry in step S2 may include at least one of water, N-methylpyrrolidone (NMP), ethanol, and common organic solvents.

[0050] In step S4 of the preparation method, the shape, area, and setting position of the carbon black positioning and marking can all be customized according to the requirements of the user. The preparation method of the present utility model has no particular limitation on the coating process. For example, it may include carrier contact transfer methods such as spraying and printing to transfer the above slurry to the surface of the separator, forming a black mark with the required shape and size specification at the set position, and then drying to obtain a stably existing carbon black positioning and marking.

[0051] In step S5 of the preparation method, there is no particular limitation on the drying method. For example, it may include methods such as heating, air blowing, and infrared radiation that can quickly volatilize the solvent.

[0052] Additionally, the present utility model provides another preparation method for a separator with a positioning mark, including the following steps: using a carbon black pen to draw a carbon black positioning and marking at a position on the separator that is at a length of L1 from the tail of the separator to obtain the separator with the carbon black positioning and marking.

[0053] In addition, the present utility model also provides a secondary battery, and the battery cell of the secondary battery includes the separator of the present utility model.

[0054] Due to the adoption of the separator with positioning marks of the present utility model, the production costs of the battery cell and the secondary battery are reduced.

[0055] The present utility model will be described in detail below in conjunction with embodiments and the accompanying drawings.

[0056] Embodiment 1

[0057] A separator with positioning marks, as Figure 1 shown, the separator 1 is composed of a separator base film 101 and a separator coating 102 provided on one side of the separator base film 101, and a carbon black positioning mark 2 is provided on the surface of one side of the separator base film 101. The distance between the carbon black positioning mark 2 and the tail of the separator is L1, and L1 is equal to the length L2 of the single-side separator of the battery cell. The carbon black positioning mark 2 is located at the edge position in the width direction of the separator. The shape of the carbon black positioning mark is an isosceles triangle, and the specification is that the bottom side length is 4 mm and the waist length is 5 mm.

[0058] The preparation method of the separator with positioning marks includes the following steps:

[0059] S1. Separator preparation: Prepare the separator according to production requirements.

[0060] S2. Carbon black marking slurry preparation: The mass ratio of carbon black: binder: dispersant: stabilizer: solvent in the carbon black marking slurry is 3:1:0.2:2:93.8. Mix the above raw materials according to the designed ratio and mechanically stir for 5 hours to form a uniform and stable carbon black positioning mark slurry. Load the carbon black positioning mark slurry into the marking brushing device.

[0061] S3. Separator slitting: Slit the separator according to the width of the separator and wind it into small rolls, and start length measurement at the same time.

[0062] S4. Carbon black positioning mark slurry brushing: Brush the carbon black positioning mark slurry on the separator at a position with a length of L1 from the tail of the separator according to the requirements of the separator user. Specifically, adopt the process of stamp-type transfer printing, and use a specified triangular mold. After dipping in the carbon black positioning mark slurry, print and coat it at the specified position of the separator.

[0063] S5. Curing and drying: Use the drying method of blowing hot air vertically downward to dry the separator after brushing the carbon black positioning mark slurry for 30 seconds to obtain a separator with a carbon black positioning mark.

[0064] Embodiment 2

[0065] This embodiment is the same as Embodiment 1, except that L1 is 1.1 times the length L2 of the separator on one side of the battery cell.

[0066] Embodiment 3

[0067] This embodiment is the same as Embodiment 1, except that L1 is 1.5 times the length L2 of the separator on one side of the battery cell.

[0068] Embodiment 4

[0069] This embodiment is the same as Embodiment 1, except that L1 is 0.5 times the length L2 of the separator on one side of the battery cell.

[0070] Embodiment 5

[0071] This embodiment is the same as Embodiment 1, except that L1 is 0.1 times the length L2 of the separator on one side of the battery cell.

[0072] Embodiment 6

[0073] This embodiment is the same as Embodiment 1, except that, as Figure 2 shown, the number of carbon black positioning marks provided on one side of the separator is two, one of the carbon black positioning marks is located at one edge position in the width direction of the separator, and the other carbon black positioning mark is located at the other edge position in the width direction of the separator, and the two carbon black positioning marks are on a straight line.

[0074] Embodiment 7

[0075] This embodiment is the same as Embodiment 1, except that the shape of the carbon black positioning mark is rectangular, with a length of 4 mm and a width of 5 mm.

[0076] Embodiment 8

[0077] This embodiment is the same as Embodiment 1, except that the shape of the carbon black positioning mark is circular, with a diameter of 6 mm.

[0078] Embodiment 9

[0079] This embodiment is the same as Embodiment 1, except that the shape of the carbon black positioning mark is star-shaped, with an area of 50 square millimeters.

[0080] Embodiment 10

[0081] This embodiment is the same as Embodiment 1, except that the method for preparing the separator includes the following steps:

[0082] S1. Separator preparation: Prepare the separator according to production requirements.

[0083] S2. Separator slitting: Slit the separator according to the width of the separator and wind it into small rolls, and start length measurement at the same time.

[0084] S3. Carbon black positioning mark production: Use a carbon black pen to draw an isosceles triangle contour on the separator at a position with a length of L1 from the tail of the separator, forming a carbon black positioning mark as shown in Figure 3 to obtain a separator with a carbon black positioning mark.

[0085] In the present utility model, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0086] Although the embodiments of the present utility model have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present utility model. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present utility model.

Claims

1. A diaphragm with positioning marks, characterized in that, A carbon black positioning mark is provided on at least one side surface of the separator; the carbon black positioning mark is entirely black, or only the outline of the carbon black positioning mark is black; the carbon black positioning mark is provided at a position close to the edge of the separator in the width direction of the separator.

2. The diaphragm with positioning marks according to claim 1, wherein The distance between the carbon black positioning mark and the tail of the separator is L1, and the length of the single-sided separator of the battery cell is L2, where L2 ≤ L1 ≤ 1.5L2.

3. The diaphragm with positioning marks according to claim 2, characterized in that, L2 ≤ L1 ≤ 1.1L2.

4. The diaphragm with positioning marks according to claim 3, characterized in that, L1 = L2.

5. The diaphragm with positioning marks according to claim 1, characterized in that, The distance between the carbon black positioning mark and the tail of the separator is L1, and the length of the single-sided separator of the battery cell is L2, where 0 < L1 < 0.5L2.

6. The diaphragm with positioning marks according to claim 5, characterized in that 0 < L1 < 0.1L2.

7. The diaphragm with positioning marks according to any one of claims 1-6, characterized in that, The shape of the carbon black positioning mark is at least one of a rectangle, a square, a triangle, and a circle; and / or the area of the carbon black positioning mark is 0.5 - 100 square millimeters.

8. A secondary battery, characterized in that, The battery cell of the secondary battery includes the separator according to any one of claims 1 - 7.

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