Diaphragm, battery cell and hot pressing tool

Abstract

The utility model discloses a diaphragm, cell and hot-pressing frock, diaphragm includes: base membrane, the same surface of base membrane has first area and second area, two first area are respectively provided the edge of base membrane opposite both ends, the second area is provided between the two first area, the first area is provided with the first area, the second area is provided with the second area, the second area is provided with the first area, the second area is provided with the second area, the second area is provided with the second area. And the adhesive heat-resistant layer is arranged in the first area. According to the diaphragm, the adhesive heat-resistant layers are arranged in the first regions at the edges of the two ends, and the area of the diaphragm coated with the adhesive heat-resistant layers is reduced, so that the use amount of the adhesive heat-resistant layers is saved, the material cost is saved, the manufacturing time of the diaphragm is also saved, and the production cost is reduced. The edges of the two ends of the diaphragm are provided with the adhesive heat-resistant layers, so that the positive pole piece and the negative pole piece can be bonded and compounded into a whole, the edges of the lamination bodies are locked, the lamination bodies are prevented from being staggered, the bonding strength of the edges of the lamination bodies is improved, and the safety and reliability of the battery cell are improved; and the overlock effect is further improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a diaphragm, a battery core and a hot pressing tool. Background Art

[0002] The booming electric vehicle market is driving power battery companies to continuously improve product performance, seek market competitiveness of their own products, and thus occupy market share. The development of electric vehicles has forced battery companies to reduce the production cost of battery cells and increase their own profit margins. The battery cell includes an anode pole piece, a diaphragm and a cathode pole piece. The diaphragm is located between the anode pole piece and the cathode pole piece. The diaphragm separates the anode pole piece and the cathode pole piece to prevent the positive and negative poles from directly contacting each other and causing internal short circuits. Both sides of the existing diaphragm are coated with an inorganic ceramic layer and a PVDF (polyvinylidene fluoride) layer to prevent thermal shrinkage in a high temperature environment, which in turn causes the positive and negative poles to directly contact each other and cause internal short circuits. This solution in which the diaphragm is completely coated with an inorganic ceramic layer and a PVDF layer is very uneconomical, and its manufacturing process is also complicated. During production, an inorganic ceramic layer is first coated on both sides of the base film, and then the PVDF layer is sprayed. This multi-step process also has high equipment requirements and time investment costs. Utility Model Content

[0003] The technical problem to be solved by the utility model is to overcome the uneconomical defect of the diaphragm in the prior art and to provide a diaphragm, a battery core and a hot pressing tool.

[0004] The utility model solves the above technical problems through the following technical solutions:

[0005] A diaphragm, comprising:

[0006] A base film, wherein the same surface of the base film has a first region and a second region, the two first regions are respectively arranged at edges of opposite ends of the base film, and the second region is arranged between the two first regions;

[0007] The viscose heat-resistant layer is arranged in the first area.

[0008] In this solution, the diaphragm is provided with a viscose heat-resistant layer in the first area at both ends of the edge. The reduction in the area of ​​the diaphragm coated with the viscose heat-resistant layer saves the amount of viscose heat-resistant layer, saves material costs, and also saves the production time of the diaphragm, reducing production costs. The viscose heat-resistant layer is provided at both ends of the diaphragm to bond the positive pole piece and the negative pole piece into one body, lock the edge of the laminate body, prevent the laminate body from being misaligned, increase the bonding strength of the edge of the laminate body, and increase the safety and reliability of the battery cell. Preferably, the viscose heat-resistant layers of adjacent diaphragms can be integrated to further improve the locking effect. The viscose heat-resistant layer is provided at both ends of the diaphragm to compensate for the thickness of the thinning area of ​​the positive pole piece and the thinning area of ​​the negative pole piece, making up for the process difficulty that the traditional hot pressing heating plate cannot fit the thinning area, and improving the yield of the battery cell.

[0009] Preferably, the second area is not provided with the viscose heat-resistant layer.

[0010] In this solution, by not setting a viscose heat-resistant layer in the second area, the amount of viscose heat-resistant layer is saved, and the material cost is saved. At the same time, when manufacturing the battery cell, since no viscose heat-resistant layer is set in the second area, the process is simplified, the manufacturing cost of the battery cell is reduced, and the economic benefit is improved.

[0011] Preferably, the first region and the second region are provided on two opposite surfaces of the base film along the thickness direction.

[0012] In this solution, the first region and the second region are arranged on both sides of the diaphragm in the thickness direction, so that the adhesive heat-resistant layer on both sides of the diaphragm can bond the adjacent pole pieces (positive pole pieces or negative pole pieces) into one body to prevent misalignment. At the same time, since no adhesive heat-resistant layer is arranged in the second region, the adjacent pole pieces are separated by the base film of the diaphragm, and a heat dissipation gap is retained between the base film and the pole pieces to improve the heat dissipation effect.

[0013] Preferably, the adhesive heat-resistant layer comprises a mixture of adhesive and ceramic.

[0014] In this solution, the adhesive mainly provides bonding force to bond the diaphragm to the pole pieces on both sides to prevent the stack from being misaligned and to prevent the diaphragm from shrinking, which would cause the positive and negative poles to short-circuit and reduce the safety of the battery cell. Ceramics are mainly used to prevent the diaphragm from shrinking in high temperature environments. The adhesive heat-resistant layer is a mixed coating. Before making the diaphragm, a mixture of adhesive and ceramic is applied to the base film at one time. Compared with the process of multiple coatings in the prior art, this simplifies the process and improves the efficiency of diaphragm production.

[0015] A battery cell, the battery cell comprising a positive electrode sheet, a negative electrode sheet, a separator as described above, and at least two tabs, the separator being arranged between the positive electrode sheet and the negative electrode sheet, the tabs being arranged on the positive electrode sheet and the negative electrode sheet respectively, the positive electrode sheet comprising a positive electrode collector and a first positive electrode coating coated on at least one side of the positive electrode collector, the negative electrode sheet comprising a negative electrode collector and a first negative electrode coating coated on at least one side of the negative electrode collector, the end of the separator being aligned with or extending outward at least relative to the end of the first negative electrode coating, the end of the first negative electrode coating being aligned with or extending outward at least relative to the end of the first positive electrode coating, the adhesive heat-resistant layer of the separator covering the area from the end of the first positive electrode coating to the end of the separator, and the adhesive heat-resistant layer and the tabs being located on the same side of the battery cell, the positive electrode sheet, the separator and the negative electrode sheet being bonded and composited into one by the adhesive heat-resistant layer of the separator.

[0016] In this embodiment, the first positive electrode coating generally includes a positive electrode active material, and the first negative electrode coating includes a negative electrode active material. The end of the diaphragm is aligned with or extended outward at least relative to the end of the first negative electrode coating, forming an overhang structure of the diaphragm to the negative electrode (referred to as S / A OH), thereby improving the separation effect and preventing internal short circuit. The end of the first negative electrode coating is aligned with or extended outward at least relative to the end of the first positive electrode coating, forming an overhang structure of the negative electrode to the positive electrode (referred to as A / C OH), thereby preventing the expansion of the electrode sheet during charging and discharging from causing internal short circuit, and preventing the thermal contraction of the diaphragm from causing internal short circuit between the positive and negative electrodes. Among them, the overhang structure refers to the portion of the negative electrode sheet that is longer and wider than the positive electrode sheet, or the portion of the diaphragm that is longer and wider than the negative electrode sheet.

[0017] The viscose heat-resistant layer of the diaphragm covers the area from the end of the first positive electrode coating to the end of the diaphragm. The viscose heat-resistant layer of the diaphragm compensates for the thickness of the electrode sheet without active material, and can also fuse adjacent diaphragms into one, preventing the stack from being misaligned, improving the edge sealing effect of the stack, and thereby avoiding short contact between the positive and negative electrodes.

[0018] Preferably, the first positive electrode coating at the end of the positive electrode current collector gradually becomes thinner in thickness from the middle to the edge to form a positive electrode thinning area, and the positive electrode current collector extends outward relative to the positive electrode thinning area to form a positive electrode current collector extension portion;

[0019] The first negative electrode coating at the end of the negative electrode current collector gradually becomes thinner from the middle to the edge to form a negative electrode thinning area, and the negative electrode current collector extends outward relative to the negative electrode thinning area to form a negative electrode current collector extension part.

[0020] In this solution, due to the tension during the coating process of the positive or negative electrode sheet, the slurry has a tendency to flow outward from the middle. If the coating gasket is not provided with a turbulent flow, the slurry discharge amount is uniform, which will cause the slurry to "pile up" at the edge of the electrode sheet. Therefore, a turbulent flow is required to gradually reduce the thickness of the first positive electrode coating at the end of the positive current collector from the middle to the edge to form a positive electrode thinning zone, so that the first positive electrode coating in the middle of the positive current collector is uniform, and the first positive electrode coating slurry at the edge of the positive electrode sheet is avoided. "Pile up" leads to the thickening of the edge of the first positive electrode coating, which affects the volume ratio of the electrode sheet. The positive current collector extends outward relative to the positive electrode thinning zone to form a positive current collector extension, which is convenient for setting a positive electrode ear on the positive current collector extension.

[0021] The thickness of the first negative electrode coating at the end of the negative electrode current collector gradually decreases from the middle to the edge to form a negative electrode thinning area, so that the first negative electrode coating in the middle of the negative electrode current collector is uniform, and the first negative electrode coating slurry at the edge of the negative electrode sheet is avoided, resulting in the thickening of the edge of the first negative electrode coating and affecting the volume ratio of the electrode sheet. The negative electrode current collector extends outward relative to the negative electrode thinning area to form a negative electrode current collector extension portion, which is convenient for setting a negative electrode tab on the negative electrode current collector extension portion.

[0022] Preferably, the first region covers part or all of the positive electrode thinning area and the negative electrode thinning area.

[0023] In the present solution, since the first region is provided with a viscose heat-resistant layer, the first region covers part or all of the positive electrode thinning area and the negative electrode thinning area, so that the viscose heat-resistant layer can compensate for the thickness of the positive electrode thinning area and the negative electrode thinning area, thereby making up for the process difficulty that the traditional hot pressing heating plate cannot fit the thinning area, thereby improving the yield of the battery cell.

[0024] Preferably, at least one side of the positive electrode current collector extension is coated with a second coating, and the thickness of the second coating is equal to or less than the minimum thickness of the first positive electrode coating.

[0025] In this solution, the second coating is an inactive substance, which is used to prevent the battery core from internal short circuits caused by sharp discharge during the charging and discharging process and under extreme conditions such as needle puncture and extrusion, thereby improving the safety of the battery core. Preferably, the second coating includes a ceramic layer or an insulating layer.

[0026] Preferably, the edges of adjacent diaphragms are bonded by the adhesive heat-resistant layer.

[0027] In this solution, the edges of adjacent diaphragms are bonded by a heat-resistant adhesive layer to form a diaphragm locking structure. The diaphragm locking structure is a structure in which the diaphragms on all sides are melted into one. After locking, the stack body will not tilt during the subsequent transfer process, the stack body into the shell, and the battery cell performance test, thereby preventing the battery cell short circuit caused by the misalignment of the overhang area.

[0028] A hot pressing tool, the hot pressing tool is used to make the battery core as described above, the hot pressing tool comprises:

[0029] Two paired heating plates, the heating plates comprising a heating zone and a non-heating zone, the non-heating zone being arranged in the middle of the heating plate, the heating zone being arranged around the non-heating zone to form a U-shaped structure, the width of the heating zone being equal to the width of the first zone, the heating zone being at least partially arranged corresponding to the first zone, and the non-heating zone being arranged corresponding to the second zone.

[0030] In this solution, the hot pressing tooling is divided into a heating zone and a non-heating zone, and the heating zone is at least partially arranged corresponding to the first zone, and the heating zone heats the viscose heat-resistant layer arranged in the first zone. Since the viscose heat-resistant layer is not arranged in the second zone, there is no need to heat it. Compared with the tooling for heating the entire surface in the corresponding technology, the heating area is small and the energy consumption is lower. In addition, a U-shaped heating plate is used for heating, so that the entire edge of the diaphragm is evenly compressed, so that the area with the viscose heat-resistant layer and the area without the viscose heat-resistant layer on the base film will maintain a thickness difference, which is used to compensate for the thickness of the positive electrode thinning area and the negative electrode thinning area, thereby achieving the effect of thickness compensation.

[0031] On the basis of conforming to the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present utility model.

[0032] The positive and progressive effect of the utility model is that the diaphragm is provided with a viscose heat-resistant layer in the first area at both ends of the edge. The reduction in the area of ​​the diaphragm coated with the viscose heat-resistant layer saves the amount of viscose heat-resistant layer, saves material costs, and also saves the production time of the diaphragm, reducing production costs. The viscose heat-resistant layer is provided at both ends of the diaphragm to bond the positive pole piece and the negative pole piece into one body, lock the edge of the laminate body, prevent the laminate body from being misaligned, increase the bonding strength of the edge of the laminate body, and increase the safety and reliability of the battery cell. Preferably, the viscose heat-resistant layers of adjacent diaphragms can be integrated to further improve the locking effect. The viscose heat-resistant layer is provided at both ends of the diaphragm to compensate for the thickness of the thinning area of ​​the positive pole piece and the thinning area of ​​the negative pole piece, making up for the process difficulty that the traditional hot pressing heating plate cannot fit the thinning area, and improving the yield of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic structural diagram of a diaphragm according to a preferred embodiment of the utility model.

[0034] Figure 2 The structure of the laminated body of a preferred embodiment of the utility model is shown in FIG. Figure 1 .

[0035] Figure 3 for Figure 2Enlarged view of part A.

[0036] Figure 4 for Figure 2 Enlarged view of part B.

[0037] Figure 5 The structure of the laminated body of a preferred embodiment of the utility model is shown in FIG. Figure 2 .

[0038] Figure 6 for Figure 5 Magnified view of part C.

[0039] Figure 7 for Figure 5 Enlarged view of part D.

[0040] Figure 8 The structure of the laminated body of a preferred embodiment of the utility model is shown in FIG. Figure 3 .

[0041] Fig. 9 The figure is a schematic structural diagram of a heating plate according to a preferred embodiment of the present invention.

[0042] Fig.10 The figure is a schematic structural diagram of a hot pressing tool and a laminated body according to a preferred embodiment of the utility model.

[0043] Description of reference numerals:

[0044] Diaphragm 1

[0045] Basement membrane 11

[0046] First Area 111

[0047] Second area 112

[0048] Positive electrode 2

[0049] Positive electrode current collector 21

[0050] Positive electrode current collector extension 211

[0051] First positive electrode coating 22

[0052] Positive electrode thinning area 221

[0053] Second coating 23

[0054] Negative plate 3

[0055] Negative electrode current collector 31

[0056] Negative electrode current collector extension 311

[0057] First negative electrode coating 32

[0058] Negative electrode thinning area 321

[0059] Overhang structure of separator to negative electrode S / A OH

[0060] Overhang structure of negative electrode to positive electrode A / C OH

[0061] Positive electrode tab 41

[0062] Negative electrode tab 42

[0063] Heating plate 5

[0064] Heating zone 51

[0065] Non-heating zone 52 DETAILED DESCRIPTION

[0066] The present invention will be described more clearly and completely below by way of embodiments in conjunction with the accompanying drawings, but the present invention is not limited to the scope of the embodiments.

[0067] like Figure 1-Figure 8 As shown, this embodiment discloses a diaphragm and its battery cell, and hot pressing tooling, specifically, as Figure 1 As shown, the diaphragm 1 includes a base film 11 and a viscose heat-resistant layer. The same surface of the base film 11 has a first area 111 and a second area 112. The two first areas 111 are respectively arranged at the edges of the opposite ends of the base film 11, the second area 112 is arranged between the two first areas 111, and the viscose heat-resistant layer is arranged in the first area 111. By arranging the viscose heat-resistant layer in the first area 111 at the edges of both ends of the diaphragm 1, the area of ​​the viscose heat-resistant layer coated on the diaphragm 1 is reduced, the amount of viscose heat-resistant layer is saved, the material cost is saved, and the production time of the diaphragm 1 is also saved, and the production cost is reduced. In the subsequent process of assembling the battery cell, the viscose heat-resistant layer is arranged at the edges of both ends of the diaphragm 1 to bond the positive electrode sheet and the negative electrode sheet into one, lock the edge of the laminate body, prevent the laminate body from being misaligned, increase the bonding strength of the edge of the laminate body, and increase the safety and reliability of the battery cell. Preferably, the viscose heat-resistant layers of adjacent diaphragms 1 can be integrated to further improve the locking effect. Based on the viscose heat-resistant layers set at the two end edges of the diaphragm 1, there is a thickness difference on the overall surface of the diaphragm 1. Relying on this thickness difference, the thickness gap caused by the existence of S / A OH, A / C OH, positive electrode sheet thinning area, and negative electrode sheet thinning area in the overall thickness direction of the battery cell can be compensated, which makes up for the problem that the diaphragm and the positive and negative electrodes in the thinning area in the thickness direction of the traditional battery cell structure cannot be tightly fitted, so that the overall thickness of the battery cell tends to be stable and consistent, effectively improving the yield of the battery cell.

[0068] like Figure 1As shown, preferably, the second region 112 is not provided with a viscose heat-resistant layer, which saves the usage of the viscose heat-resistant layer and saves material costs. At the same time, when manufacturing the battery cell, since the second region 112 is not provided with a viscose heat-resistant layer, the process is simplified, the manufacturing cost of the battery cell is reduced, and the economic benefits are improved.

[0069] The first region 111 and the second region 112 are provided on two surfaces opposite to each other in the thickness direction of the base film 11. By providing the first region 111 and the second region 112 on both sides of the diaphragm 1 in the thickness direction, it is convenient for the adhesive heat-resistant layer on both sides of the diaphragm 1 to bond and composite the adjacent pole pieces into one body to prevent misalignment. At the same time, since the adhesive heat-resistant layer is not provided in the second region 112, the adjacent pole pieces are separated by the base film 11 of the diaphragm 1, and a heat dissipation gap is retained between the base film 11 and the pole piece, thereby improving the heat dissipation effect.

[0070] In this embodiment, the viscose heat-resistant layer includes a mixture of adhesive and ceramic. The adhesive mainly provides bonding force, which is used to bond the diaphragm 1 to the pole pieces on both sides to prevent the stack from being misaligned, and also to prevent the diaphragm 1 from shrinking, resulting in short contact between the positive and negative poles, and reducing the safety of the battery cell. Ceramics are mainly used to prevent the diaphragm 1 from thermal shrinkage in a high temperature environment. The viscose heat-resistant layer is a mixed coating. Before making the diaphragm 1, a mixture of adhesive and ceramic is applied to the base film 11 at one time. Compared with the process of multiple coatings in the prior art, the process is simplified and the production efficiency of the diaphragm 1 is improved. Preferably, the viscose heat-resistant layer is a mixed layer of PVDF (polyvinylidene fluoride) and Al2O3 ceramic.

[0071] like Figure 5 and Figure 6 As shown, this embodiment also discloses a battery cell, which includes a positive electrode sheet 2, a negative electrode sheet 3, a separator 1 as described above, and at least two tabs. The separator 1 is arranged between the positive electrode sheet 2 and the negative electrode sheet 3, and the tabs are arranged on the positive electrode sheet 2 and the negative electrode sheet 3, respectively. The positive electrode sheet 2 includes a positive electrode collector 21 and a first positive electrode coating 22 coated on at least one side of the positive electrode collector 21, and the negative electrode sheet 3 includes a negative electrode collector 31 and a first negative electrode coating 32 coated on at least one side of the negative electrode collector 31. The first positive electrode coating 22 includes a positive electrode active material, and the first negative electrode coating 32 includes a negative electrode active material. The end of the separator 1 is aligned with or extended outward at least relative to the end of the first negative electrode coating 32, forming an overhang structure (abbreviated as S / AOH) of the separator 1 to the negative electrode, which improves the separation effect and prevents internal shorting. The end of the first negative electrode coating 32 is at least aligned with or extended outward relative to the end of the first positive electrode coating 22 to form an overhang structure of the negative electrode to the positive electrode (abbreviated as A / C OH), which prevents the expansion of the electrode sheet during charging and discharging to cause an internal short circuit, and also prevents the positive and negative electrodes from contacting each other due to thermal shrinkage of the diaphragm 1, resulting in an internal short circuit.

[0072] Among them, the overhang structure refers to the part of the negative electrode sheet (with a first negative electrode coating) that exceeds the positive electrode sheet (with a first positive electrode coating) in length and width, or the part of the diaphragm 1 that exceeds the negative electrode sheet (with a first negative electrode coating) in length and width.

[0073] like Figure 2-Figure 8 As shown, the adhesive heat-resistant layer of the separator 1 covers the area from the end of the first positive electrode coating 22 to the end of the separator 1, and the adhesive heat-resistant layer and the pole ear are located on the same side of the battery cell, and the positive electrode sheet 2, the separator 1 and the negative electrode sheet 3 are bonded and compounded into one body through the adhesive heat-resistant layer of the separator 1 to form a laminated body. The adhesive heat-resistant layer of the separator 1 compensates the thickness of the pole sheet without active material, and can also fuse adjacent separators 1 into one body, prevent the laminated body from being misaligned, improve the edge sealing effect of the laminated body, and thus avoid the positive and negative electrodes from contacting each other.

[0074] like Figure 5-Figure 7 As shown, during the coating process of the positive electrode sheet or the negative electrode sheet, due to the tension, the slurry has a tendency to flow outward from the middle. If the coating gasket is not provided with a turbulent flow, the slurry discharge amount is uniform, which will cause the slurry to "pile up" at the edge of the electrode sheet, so turbulence is required. The thickness of the first positive electrode coating 22 at the end of the positive electrode collector 21 gradually decreases from the middle to the edge to form a positive electrode thinning area 221, avoiding the "pile up" of the first positive electrode coating 22 slurry at the edge of the positive electrode sheet 2, resulting in the thickening of the edge of the first positive electrode coating 22, so that the first positive electrode coating 22 in the middle of the positive electrode collector 21 is uniform, and the volume ratio of the electrode sheet is improved.

[0075] like Figure 5-Figure 7 As shown, the positive electrode current collector 21 extends outward relative to the positive electrode thinned area 221 to form a positive electrode current collector extension portion 211 , which facilitates the arrangement of the positive electrode tab 41 on the positive electrode current collector extension portion 211 .

[0076] like Figure 5-Figure 7 As shown, the thickness of the first negative electrode coating 32 at the end of the negative electrode current collector 31 gradually decreases from the middle to the edge to form a negative electrode thinning area 321, so that the first negative electrode coating 32 in the middle of the negative electrode current collector 31 is uniform, and the "accumulation" of the first negative electrode coating 32 slurry at the edge of the negative electrode sheet 3 is avoided, which leads to the thickening of the edge of the first negative electrode coating 32 and affects the volume ratio of the electrode sheet.

[0077] like Figure 5-Figure 7 As shown, the negative electrode current collector 31 extends outward relative to the negative electrode thinned area 321 to form a negative electrode current collector extension portion 311 , which facilitates the arrangement of the negative electrode tab 42 on the negative electrode current collector extension portion 311 .

[0078] like Figure 5-Figure 7As shown, the first region 111 covers part or all of the positive electrode thinning area 221 and the negative electrode thinning area 321. Since the first region 111 is provided with a viscose heat-resistant layer, the viscose heat-resistant layer can compensate for the thickness of the positive electrode sheet thinning area and the negative electrode sheet thinning area by covering part or all of the positive electrode sheet thinning area 221 and the negative electrode sheet thinning area 321 by the first region 111, making up for the process difficulty that the traditional hot pressing heating plate 5 cannot fit the thinning area, thereby improving the yield rate of the battery cell.

[0079] like Figure 5-Figure 7 As shown, at least one side of the positive current collector extension 211 is coated with a second coating 23, and the thickness of the second coating 23 is equal to or less than the minimum thickness of the first positive electrode coating 22. The second coating 23 is an inactive substance, which is used to prevent the battery cell from causing internal short circuits due to sharp discharge during the charge and discharge process and under extreme conditions such as needle puncture and extrusion, thereby improving the safety of the battery cell. Preferably, the second coating 23 includes a ceramic layer.

[0080] The edges of adjacent diaphragms 1 are bonded by adhesive heat-resistant layers. By bonding the edges of adjacent diaphragms 1 by adhesive heat-resistant layers, a diaphragm 1 locking structure is formed. The diaphragm 1 locking structure is that the diaphragms 1 and diaphragms 1 on all sides are melted into one. After locking, the laminated body will not tilt during the subsequent transfer process, the laminated body into the shell, and the battery performance test process, preventing the battery short circuit caused by the overhang area misalignment.

[0081] like Fig. 9 and Fig.10 As shown, this embodiment also discloses a hot pressing tooling, which is used to make the battery cell as described above, and the hot pressing tooling includes two paired heating plates 5. The heating plate 5 includes a heating area 51 and a non-heating area 52, the non-heating area 52 is arranged in the middle of the heating plate 5, and the heating area 51 is arranged around the non-heating area 52 to form a U-shaped structure. The width of the heating area 51 is equal to the width of the first area 111, and the heating area 51 is at least partially arranged corresponding to the first area 111, and the non-heating area 52 is arranged corresponding to the second area 112. By dividing the hot pressing tooling into a heating area 51 and a non-heating area 52, and the heating area 51 is at least partially arranged corresponding to the first area 111, the heating area 51 heats the viscose heat-resistant layer arranged in the first area 111. Since the second area 112 is not provided with a viscose heat-resistant layer, it does not need to be heated. Compared with the tooling for heating the entire surface in the corresponding technology, the heating area is small and the energy consumption is lower. In addition, a U-shaped heating plate 5 is used for heating, so that the edge of the entire diaphragm 1 is evenly compressed, so that the area with the adhesive heat-resistant layer and the area without the adhesive heat-resistant layer on the base film 11 will maintain a thickness difference, which is used to compensate for the thickness of the positive electrode thinning area 221 and the negative electrode thinning area 321, thereby achieving the effect of thickness compensation. At the same time, the edge of the second area 112 of the diaphragm 1 is also heat-pressed and bonded, so that the entire battery cell forms a stable locked edge structure.

[0082] The following introduces different embodiments of designing and manufacturing the diaphragm and hot pressing tooling containing the utility model.

[0083] Embodiment 1:

[0084] A design of a diaphragm and a hot pressing auxiliary tooling, the design scheme includes the following steps:

[0085] 1. Taking the short-side tabs on both sides of the soft-pack battery as an example, the diaphragm length is designed according to the pole piece size and OH (Overhang) specifications. The negative electrode film length is 504mm, and the OH of the negative electrode to the short side of the diaphragm is 2.75mm. Therefore, the minimum film length required for the diaphragm is 509.5mm. Considering the thermal shrinkage of the diaphragm, the diaphragm film length in this example is customized to 511.5mm;

[0086] 2. Customize the heating area of ​​the U-shaped heating plate according to the size of the electrode and the OH specification. The short side OH of the negative electrode to the diaphragm is 1.2mm, the long side OH is 1.0mm, the negative electrode film is 504mm long and 98.5mm wide. Therefore, the short side width of the heating area of ​​the heating plate is 1.2mm, the long side width is 1.0mm, and the non-heating area of ​​the hot plate is 504mm long and 98.5mm wide.

[0087] 3. The lamination adopts "Z-shaped" stacking process, using hot pressing tooling and low-temperature long-time heating method. The heating zone of the heating plate is controlled at 95°C, the hot pressing time is 300s, and the hot pressing pressure is 10.0t;

[0088] 4. The subsequent packaging and chemical formation process of the stacked body is no different from the traditional process.

[0089] Embodiment 2:

[0090] A design of a diaphragm and a hot pressing auxiliary tooling, the design scheme includes the following steps:

[0091] 1. Taking the short side tabs on both sides of the soft-pack battery as an example, the diaphragm film length and diaphragm glue width are designed according to the pole piece size and OH specifications. The negative electrode film length is 504mm, and the negative electrode is 2.75mm on the short side of the diaphragm. In this case, the non-glue area of ​​the diaphragm is customized to be 504mm, and the glue-enhanced areas on both sides are sprayed with 1g / cm 2 The PVDF and Al2O3 ceramic mixed layer is cut off from the excess edge glue-increasing area. Considering the thermal shrinkage of the diaphragm, the glue-increasing width is kept at 4.75mm in this example.

[0092] 2. Customize the heating area of ​​the U-shaped heating plate according to the size of the electrode and the OH specification. The short side OH of the negative electrode to the diaphragm is 1.2mm, the long side OH is 1.0mm, the negative electrode film is 504mm long and 98.5mm wide. Therefore, the short side width of the heating area of ​​the heating plate is 1.2mm, the long side width is 1.0mm, and the non-heating area of ​​the heating plate is 504mm long and 98.5mm wide.

[0093] 3. The stacking of the lamination body adopts the "Z-shaped" process, and the diaphragm uses an edge-added diaphragm, and the added glue area corresponds to the OH side of the short side of the negative electrode diaphragm;

[0094] 4. Use hot pressing auxiliary device and low temperature long time heating method, the heating zone of the heating plate is controlled at 95℃, the hot pressing time is 300s, and the hot pressing pressure is 10.0t;

[0095] 5. The subsequent packaging and chemical formation process of the stacked body is no different from the traditional process.

[0096] Embodiment 3:

[0097] A design of a diaphragm and a hot pressing auxiliary tooling, the design scheme includes the following steps:

[0098] 1. Taking the short-side tabs on both sides of the soft-pack battery as an example, the diaphragm length is designed according to the pole piece size and OH specifications. The negative electrode film length is 504mm, and the OH of the short side of the negative electrode to the diaphragm is 2.75mm. Therefore, the minimum required diaphragm film length is 509.5mm. Considering the thermal shrinkage of the diaphragm, the diaphragm film length in this example is customized to 511.5mm;

[0099] 2. Customize the heating area of ​​the U-shaped heating plate according to the size of the electrode and the OH specification. The short side OH of the negative electrode to the diaphragm is 1.2mm, the long side OH is 1.0mm, the negative electrode film is 504mm long and 98.5mm wide. Therefore, the short side width of the heating area of ​​the heating plate is 1.2mm, the long side width is 1.0mm, and the non-heating area of ​​the heating plate is 504mm long and 98.5mm wide.

[0100] 3. The lamination adopts "Z-shaped" stacking process, using hot pressing auxiliary device and high temperature short-time heating method. The heating zone of the heating plate is controlled at 150°C, the hot pressing time is 60s, and the hot pressing pressure is 10.0t;

[0101] 4. The subsequent packaging and chemical formation process of the stacked body is no different from the traditional process.

[0102] Embodiment 4:

[0103] A design of a diaphragm and a hot pressing auxiliary tooling, the design scheme includes the following steps:

[0104] 1. Taking the short side tabs on both sides of the soft-pack battery as an example, the diaphragm film length and diaphragm glue width are designed according to the pole piece size and OH specifications. The negative electrode film length is 504mm, and the negative electrode is 2.75mm on the short side of the diaphragm. In this case, the non-glue area of ​​the diaphragm is customized to be 504mm, and the glue-enhanced areas on both sides are sprayed with 1g / cm 2 The PVDF and Al2O3 ceramic mixed layer is cut off from the excess edge glue-increasing area. Considering the thermal shrinkage of the diaphragm, the glue-increasing width is kept at 4.75mm in this example.

[0105] 2. Customize the heating area of ​​the U-shaped heating plate according to the size of the electrode and the OH specification. The short side OH of the negative electrode to the diaphragm is 1.2mm, the long side OH is 1.0mm, the negative electrode film is 504mm long and 98.5mm wide. Therefore, the short side width of the heating area of ​​the heating plate is 1.2mm, the long side width is 1.0mm, and the non-heating area of ​​the heating plate is 504mm long and 98.5mm wide.

[0106] 3. The stacking of the lamination body adopts the "Z-shaped" process, and the diaphragm uses an edge-added diaphragm, and the added glue area corresponds to the OH side of the short side of the negative electrode diaphragm;

[0107] 4. Use hot pressing auxiliary device and high temperature short-time heating method, the heating zone of the heating plate is controlled at 150°C, the hot pressing time is 60s, and the hot pressing pressure is 10.0t;

[0108] 5. The subsequent packaging and chemical formation process of the stacked body is no different from the traditional process.

[0109] The effects of the above-mentioned embodiments 1 to 5 are compared and are shown in the following table.

[0110]

[0111] In the table, JR is the abbreviation for bare cell, and OH is the abbreviation for Overhang.

[0112] The following additional examples and comparative examples are provided to illustrate that the technical effect of edge locking can be achieved when the temperature is controlled within 92°C-170°C, while a temperature lower than or higher than 92°C-170°C will bring about negative effects.

[0113] Embodiment 1:

[0114] 1. Taking the short-side tabs on both sides of the soft-pack battery as an example, the diaphragm length is designed according to the pole piece size and OH specifications. The negative electrode film length is 504mm, and the OH of the short side of the negative electrode to the diaphragm is 2.75mm. Therefore, the minimum required diaphragm film length is 509.5mm. Considering the thermal shrinkage of the diaphragm, the diaphragm film length in this example is customized to 511.5mm;

[0115] 2. Customize the heating area of ​​the U-shaped heating plate according to the size of the electrode and the OH specification. The short side OH of the negative electrode to the diaphragm is 1.2mm, the long side OH is 1.0mm, the negative electrode film is 504mm long and 98.5mm wide. Therefore, the short side width of the heating area of ​​the heating plate is 1.2mm, the long side width is 1.0mm, and the non-heating area of ​​the heating plate is 504mm long and 98.5mm wide.

[0116] 3. The lamination adopts "Z-shaped" stacking process, using hot pressing auxiliary device and low-temperature long-time heating method. The heating zone of the heating plate is controlled at 95°C, the hot pressing time is 300s, and the hot pressing pressure is 10.0t;

[0117] 4. The subsequent packaging and chemical formation process of the stacked body is no different from the traditional process.

[0118] Embodiment 2:

[0119] 1. Taking the short-side tabs on both sides of the soft-pack battery as an example, the diaphragm length is designed according to the pole piece size and OH specifications. The negative electrode film length is 504mm, and the OH of the short side of the negative electrode to the diaphragm is 2.75mm. Therefore, the minimum required diaphragm film length is 509.5mm. Considering the thermal shrinkage of the diaphragm, the diaphragm film length in this example is customized to 511.5mm;

[0120] 2. Customize the heating area of ​​the U-shaped heating plate according to the size of the electrode and the OH specification. The short side OH of the negative electrode to the diaphragm is 1.2mm, the long side OH is 1.0mm, the negative electrode film is 504mm long and 98.5mm wide. Therefore, the short side width of the heating area of ​​the heating plate is 1.2mm, the long side width is 1.0mm, and the non-heating area of ​​the heating plate is 504mm long and 98.5mm wide.

[0121] 3. The lamination adopts "Z-shaped" stacking process, using hot pressing auxiliary device, the heating zone of the heating plate is controlled at 60°C, the hot pressing time is 300s, and the hot pressing pressure is 10.0t;

[0122] 4. The subsequent packaging and chemical formation process of the stacked body is no different from the traditional process.

[0123] Embodiment 3:

[0124] 1. Taking the short-side tabs on both sides of the soft-pack battery as an example, the diaphragm length is designed according to the pole piece size and OH specifications. The negative electrode film length is 504mm, and the OH of the short side of the negative electrode to the diaphragm is 2.75mm. Therefore, the minimum required diaphragm film length is 509.5mm. Considering the thermal shrinkage of the diaphragm, the diaphragm film length in this example is customized to 511.5mm;

[0125] 2. Customize the heating area of ​​the U-shaped heating plate according to the size of the electrode and the OH specification. The short side OH of the negative electrode to the diaphragm is 1.2mm, the long side OH is 1.0mm, the negative electrode film is 504mm long and 98.5mm wide. Therefore, the short side width of the heating area of ​​the heating plate is 1.2mm, the long side width is 1.0mm, and the non-heating area of ​​the heating plate is 504mm long and 98.5mm wide.

[0126] 3. The lamination adopts "Z-shaped" stacking process, using hot pressing auxiliary device, the heating zone of the heating plate is controlled at 200℃, the hot pressing time is 300s, and the hot pressing pressure is 10.0t;

[0127] 4. The subsequent packaging and chemical formation process of the stacked body is no different from the traditional process.

[0128] The effects of the above-mentioned embodiments 1 to 3 are compared and shown in the following table.

[0129]

[0130] In the table, JR is the abbreviation for bare cell, and OH is the abbreviation for Overhang.

[0131] In the description of this article, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0132] Although the specific implementations of the utility model are described above, those skilled in the art should understand that this is only an example, and the protection scope of the utility model is defined by the attached claims. Those skilled in the art can make various changes or modifications to these implementations without departing from the principle and essence of the utility model, but these changes and modifications fall within the protection scope of the utility model.

Claims

1. A diaphragm, characterized in that: The diaphragm comprises: A base film, wherein the same surface of the base film has a first region and a second region, the two first regions are respectively arranged at edges of opposite ends of the base film, and the second region is arranged between the two first regions; The viscose heat-resistant layer is arranged in the first area.

2. The diaphragm according to claim 1, characterized in that The second region is not provided with the viscose heat-resistant layer.

3. The diaphragm according to claim 2, characterized in that The first region and the second region are disposed on two surfaces of the base film that are opposite to each other in the thickness direction.

4. The diaphragm according to claim 1, characterized in that The adhesive heat-resistant layer comprises a mixture of adhesive and ceramic.

5. A battery cell, characterized in that: The battery cell comprises a positive electrode sheet, a negative electrode sheet, a separator as described in any one of claims 1 to 4, and at least two pole tabs, the separator is arranged between the positive electrode sheet and the negative electrode sheet, and the pole tabs are arranged on the positive electrode sheet and the negative electrode sheet respectively, the positive electrode sheet comprises a positive electrode collector and a first positive electrode coating coated on at least one side of the positive electrode collector, the negative electrode sheet comprises a negative electrode collector and a first negative electrode coating coated on at least one side of the negative electrode collector, the end of the separator is at least aligned with or extended outward relative to the end of the first negative electrode coating, the end of the first negative electrode coating is at least aligned with or extended outward relative to the end of the first positive electrode coating, the adhesive heat-resistant layer of the separator covers the area from the end of the first positive electrode coating to the end of the separator, and the adhesive heat-resistant layer and the pole tab are located on the same side of the battery cell, and the positive electrode sheet, the separator and the negative electrode sheet are bonded and composited into one by the adhesive heat-resistant layer of the separator.

6. The battery cell according to claim 5, characterized in that: The first positive electrode coating at the end of the positive electrode current collector gradually becomes thinner from the middle to the edge to form a positive electrode thinning area, and the positive electrode current collector extends outward relative to the positive electrode thinning area to form a positive electrode current collector extension part; The first negative electrode coating at the end of the negative electrode current collector gradually becomes thinner from the middle to the edge to form a negative electrode thinning area, and the negative electrode current collector extends outward relative to the negative electrode thinning area to form a negative electrode current collector extension part.

7. The battery cell according to claim 6, characterized in that: The first region covers part or all of the positive electrode thinning area and the negative electrode thinning area.

8. The battery cell according to claim 6, characterized in that: At least one side of the positive electrode current collector extension is coated with a second coating layer, and the thickness of the second coating layer is equal to or less than the minimum thickness of the first positive electrode coating layer.

9. The battery cell according to claim 5, characterized in that: The edges of the adjacent diaphragms are bonded by the adhesive heat-resistant layer.

10. A hot pressing tool, characterized in that: The hot pressing tool is used to manufacture the battery cell according to any one of claims 5 to 9, and the hot pressing tool comprises: Two paired heating plates, the heating plates comprising a heating zone and a non-heating zone, the non-heating zone being arranged in the middle of the heating plate, the heating zone being arranged around the non-heating zone to form a U-shaped structure, the width of the heating zone being equal to the width of the first zone, the heating zone being at least partially arranged corresponding to the first zone, and the non-heating zone being arranged corresponding to the second zone.

Images