Battery

Abstract

The utility model discloses a battery, which relates to the technical field of batteries, and comprises a battery cell body and a packaging body for packaging the battery cell body, and the battery cell body comprises tabs; the packaging body comprises a top sealing edge, and the tab extends out of the packaging body from the top sealing edge along a first direction; the top sealing edge comprises an inner unsealed area and a sealing area arranged on one side of the inner unsealed area in the extending direction of the tab; the packaging body comprises a first packaging film and a second packaging film which are oppositely arranged, and each of the first packaging film and the second packaging film comprises an outer protection layer, an inner polymer layer and a metal layer located between the outer protection layer and the inner polymer layer; the included angle theta formed between the first packaging film and the second packaging film at the end part of the top sealing edge in the extension direction of the tab meets the formula: theta < lt >; 30 degrees. Due to the fact that the included angle of the original outer unsealed area is large, the included angle theta formed between the first packaging film and the second packaging film of the sealed area after cutting is reduced, the tension on the top sealing outer layer protection gummed paper is reduced, the problem that due to the fact that the included angle theta is too large, rubber coating is poor is solved, and the production yield of the battery is improved.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a battery. Background Technology

[0002] Taking pouch lithium-ion batteries as an example, lightweight encapsulation films (such as aluminum-plastic films) are used as battery casing materials. The battery is sealed by heating and melting the polypropylene layer inside the aluminum-plastic film. Therefore, pouch lithium-ion batteries have advantages such as high energy density, high safety performance and high capacity, and are widely used in the consumer electronics field.

[0003] In the production of pouch lithium-ion batteries, sealing the battery edges to ensure its airtightness is a crucial step. To prevent adhesive overflow from contaminating the sealing head after sealing, an unsealed area is usually set outside the sealing area. However, due to the heat and pressure during encapsulation, this unsealed area opens up into a flared shape after battery encapsulation. At the battery pack end, to prevent short circuits between the metal layer at the end of the top sealing film area and the tabs or protection board, adhesive tape is usually applied to the unsealed area of ​​the top sealing edge to cover it. Currently, the angle between the two layers of sealing film in the top sealing area of ​​batteries is too large. This causes significant rebound tension on the outer adhesive tape when applying it to the top sealing edge, easily leading to defects such as misaligned tape application and insufficient tape coverage of the top sealing area, resulting in low production yield during battery production. Utility Model Content

[0004] The purpose of this invention is to provide a battery that improves the problem of poor adhesive tape covering the top sealing edge caused by an excessively large included angle between the first and second sealing films on the top sealing edge, thereby increasing the battery production yield.

[0005] To achieve the above objectives, this utility model provides a battery, including a cell body and a package for encapsulating the cell body, wherein the cell body includes tabs;

[0006] The package includes a top seal edge, and an electrode tab extends out of the package body from the top seal edge along a first direction; the top seal edge includes an inner unsealed area and a sealing area disposed outside the inner unsealed area along the direction in which the electrode tab extends.

[0007] The encapsulation body includes a first encapsulation film and a second encapsulation film disposed opposite to each other. Both the first encapsulation film and the second encapsulation film include an outer protective layer, an inner polymer layer, and a metal layer located between the outer protective layer and the inner polymer layer.

[0008] Along the extension direction of the tab, the included angle θ formed between the first encapsulation film and the second encapsulation film at the top sealing edge end satisfies: θ < 30°.

[0009] In some embodiments, the length of the top sealing edge along the extension direction of the tab satisfies the following: X is in the range of 0.7mm-2.5mm, preferably 1.0mm-1.8mm; where X is the length of the top sealing edge.

[0010] In some embodiments, along the extension direction of the tab, the length of the inner unsealed area and the length of the top seal edge satisfy the following condition: Y / X ranges from 0.1 to 0.8, where X is the length of the top seal edge and Y is the length of the inner unsealed area.

[0011] In some embodiments, the length of the sealing area along the extension direction of the tab satisfies the following: L is in the range of 0.5mm-1.8mm, preferably 0.6mm-1.5mm; wherein L is the length of the sealing area along the extension direction of the tab.

[0012] In some embodiments, the tab is provided with tab adhesive, and the sealing area includes a first segment along a second direction. The first segment includes a first part and a second part. In the first part, the inner polymer layer of the first encapsulation film and the inner polymer layer of the second encapsulation film are bonded together. In the second part, the inner polymer layer of the first encapsulation film and / or the inner polymer layer of the second encapsulation film are bonded to the tab adhesive. The sealing area also includes a second segment along the extension direction of the tab. The second part is connected to the second segment, and the second direction is perpendicular to the extension direction of the tab.

[0013] Along the extension direction of the tab, the distance between the side edge of the second segment near the second part and the end edge of the first part satisfies: |H|≤0.3mm, where |H| is the absolute difference between the side edge of the second segment near the second part and the end edge of the first part.

[0014] In some embodiments, along the extension direction of the electrode tab, the length of the second segment and the length of the first portion satisfy the following: the ratio of Z / L0 is in the range of 10%-70%; where Z is the length of the second segment along the extension direction of the electrode tab; and L0 is the length of the first portion along the extension direction of the electrode tab.

[0015] And / or, along the extension direction of the tab, the length of the second segment satisfies: Z is in the range of 0.3mm-1mm, where Z is the length of the second segment along the extension direction of the tab.

[0016] In some embodiments, the second segment includes a first region, a second region, and a third region sequentially arranged along the extension direction of the electrode tab; or, the second segment includes a second region and a third region sequentially arranged along the extension direction of the electrode tab.

[0017] Along the extension direction of the tab, the first region is connected to the second part; along the third direction, the thickness of the second region is greater than the thickness of the first region, and / or, the thickness of the second region is greater than the thickness of the third region;

[0018] And / or, in the extending direction of the tab, the length of the third region: A≤0.2 mm, where A is the length of the third region in the extending direction of the tab;

[0019] And / or, in the extending direction of the tab, the length of the second region: B≤0.2 mm, where B is the length of the second region in the extending direction of the tab.

[0020] In some embodiments, an ear glue that is not in contact with the inner polymer layer of the first encapsulation film and / or the second encapsulation film is provided on the portion of the tab extending outside the sealing region, and the ear glue is connected to the second segment;

[0021] Along the third direction, the following is satisfied between the thickness of the second region and the thickness of the ear glue: C≥D, where C is the thickness of the second region and D is the thickness of the ear glue provided on the portion of the tab extending outside the sealing region and not in contact with the inner polymer layer of the first encapsulation film and / or the second encapsulation film;

[0022] And / or, along the third direction, the thickness of the second region satisfies: the range of C is 0.05 mm - 1 mm, preferably 0.08 mm - 0.8 mm; where C is the thickness of the second region.

[0023] In some embodiments, in the second direction, the absolute difference between the length of the second segment and the length of the second portion satisfies: |L1 - L2| < 0.2 mm; where L1 is the length of the second segment in the second direction and L2 is the length of the second portion in the second direction.

[0024] In some embodiments, a first metal layer exposed region is provided at one end of the metal layer of the first encapsulation film facing the outer protective layer;

[0025] And / or, a second metal layer exposed region is provided at one end of the metal layer of the second encapsulation film facing the outer protective layer;

[0026] In the extending direction of the tab, the following is satisfied for the first metal layer exposed region and the second metal layer exposed region: L4 < L3; where L3 is the length of the first metal layer exposed region in the extending direction of the tab; L4 is the length of the second metal layer exposed region in the extending direction of the tab;

[0027] And / or, the length of the second metal layer exposed region in the extending direction of the tab satisfies: L4 < 100 um, where L4 is the length of the second metal layer exposed region in the extending direction of the tab.

[0028] In some embodiments, a third metal layer exposed region is provided at one end of the sealing region away from the inner unsealed region;

[0029] Along the extension direction of the tab, the exposed area of ​​the third metal layer satisfies: L5 < 50 μm; where L5 is the length of the exposed area of ​​the third metal layer in the extension direction of the tab.

[0030] In some embodiments, the first metal layer exposed area and / or the second metal layer exposed area and / or the third metal layer exposed area are provided with burrs;

[0031] The width of the burr along the second direction: M1 < 20um, where M1 is the width of the burr along the second direction;

[0032] And / or, the height of the burr along the extension direction of the tab: M2 < 50 μm, where M2 is the height of the burr along the extension direction of the tab.

[0033] Compared to the prior art, this utility model provides a battery, which includes a cell body and a package body for encapsulating the cell body. The cell body includes tabs; the package body includes a first encapsulation film and a second encapsulation film disposed opposite to each other. Both the first and second encapsulation films include an outer protective layer, an inner polymer layer, and a metal layer located between the outer protective layer and the inner polymer layer; the package body includes a top sealing edge, and the tabs extend out of the package body from the top sealing edge along a first direction; the top sealing edge includes an inner unsealed area and a sealing area located inside the inner unsealed area along the direction of extension of the tabs; the included angle θ formed between the first and second encapsulation films satisfies: θ < 30°; the battery provided by this utility model solves the problem of poor top sealing edge encapsulation in subsequent production processes caused by the excessively large opening angle of the encapsulation films on both sides of the top sealing edge area in the prior art. The included angle θ formed between the first and second encapsulation films in the sealing area provided by this utility model is smaller, thereby reducing the rebound force on the outer protective adhesive paper of the top seal, reducing the problem of poor top sealing edge encapsulation caused by the excessively large included angle θ, and improving the production yield of the battery. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0035] Figure 1 A schematic diagram of the top sealing edge of the battery provided in an embodiment of this utility model;

[0036] Figure 2 for Figure 1 A schematic diagram of the unsealed and sealed areas within the central region;

[0037] Figure 3 for Figure 2A schematic diagram of the central sealing area after being subjected to the laser thermal effect;

[0038] Figure 4 for Figure 1 A schematic diagram showing the connection between the central sealing area, the electrode tabs, and the electrode tab adhesive;

[0039] Figure 5 for Figure 4 A diagram of the second section;

[0040] Figure 6 for Figure 4 Another diagram of the second section;

[0041] Figure 7 This is a schematic diagram of the processing flow of the top sealing edge of the battery provided in an embodiment of the present utility model;

[0042] Figure 8 for Figure 7 A magnified view of part E in the image;

[0043] Figure 9 for Figure 1 A schematic diagram of the burrs on the top edge of the seal.

[0044] The attached figures are labeled as follows:

[0045] Package 1, tab 2, and tab adhesive 3;

[0046] Top edge sealing 10, inner unsealed area 11 and sealed area 12;

[0047] First encapsulation film 121, second encapsulation film 122, first segment 123, second segment 124, first metal layer exposed area 125, second metal layer exposed area 126, third metal layer exposed area 127, and burr 128;

[0048] Outer protective layer 1201, metal layer 1202 and inner polymer layer 1203;

[0049] Part 1 1231 and Part 2 1232

[0050] Zone 1: 1241; Zone 2: 1242; Zone 3: 1243. Detailed Implementation

[0051] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0052] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] This utility model discloses a battery, as shown in the attached figure. Figure 1 As shown, the package includes a battery cell body and a package 1 that encapsulates the battery cell body. The battery cell body includes tabs 2. The package 1 includes a top sealing edge 10, and the tabs 2 extend from the top sealing edge 10 out of the package 1 along a first direction. The first direction in this document refers to the direction in which the tabs 2 extend. The top sealing edge 10 includes an inner unsealed area 11 and a sealing area 12 disposed on one side of the inner unsealed area 11 along the direction in which the tabs 2 extend.

[0054] The package 1 includes a first encapsulation film 121 and a second encapsulation film 122 disposed opposite to each other. Both the first encapsulation film 121 and the second encapsulation film 122 include an outer protective layer 1201, an inner polymer layer 1203, and a metal layer 1202 located between the outer protective layer 1201 and the inner polymer layer 1203. The outer protective layer 1201 may be a nylon layer, the inner polymer layer 1203 may be a polypropylene layer, and the metal layer 1202 may be an aluminum foil layer. Both the first encapsulation film 121 and the second encapsulation film 122 are single-layer aluminum-plastic films.

[0055] As attached Figure 2As shown, along the extension direction of the tab 2, the included angle θ formed between the first encapsulation film 121 and the second encapsulation film 122 at the end of the top sealing edge 10 satisfies: θ < 30°; preferably, the included angle θ ≤ 20°; more preferably, the included angle θ ≤ 15°; along the extension direction of the tab 2, the included angle θ formed between the first encapsulation film 121 and the second encapsulation film 122 at the end of the top sealing edge 10 satisfies: θ < 30°; preferably, the included angle θ ≤ 25°; more preferably, the included angle θ ≤ 15°; for example, the included angle θ can be 0°, 5°, 8°, 10°, 15°, 20°, 25°, 27°, or 28°. Wherein θ is the included angle between the two rays formed by the first encapsulation film 121 and the second encapsulation film 122 at the end of the top sealing edge 10 along the extension direction of the tab 2. In one embodiment of this utility model, the top sealing edge of the battery can be cut and cleaned to reduce the included angle between the two layers of encapsulation film in the top sealing edge area of ​​the battery, so that the included angle θ formed between the first encapsulation film 121 and the second encapsulation film 122 satisfies: θ<30°, thereby improving the yield of top sealing edge adhesive during the battery PACK process. In existing batteries, the top seal edge has an unsealed area. While the encapsulation films in the sealing area of ​​the top seal edge are bonded together, the inner polymer layers between the two encapsulation films on either side of the unsealed area are not bonded together. Therefore, there is no binding force between the two inner polymer layers, resulting in a large angle between them. In one embodiment of this invention, laser cutting is used on the sealing area of ​​the top seal edge to remove the unsealed area. In some embodiments, besides laser cutting to remove the unsealed area, laser cleaning can be used to treat the unsealed area at the tab position, since cutting at the tab position can easily damage it. This results in a battery with the unsealed area removed. In other words, in one embodiment, the top seal edge of the battery provided by this solution consists of an inner unsealed area and a sealing area. This not only reduces the angle between the two encapsulation films in the top seal edge area, improving the top seal encapsulation yield, but also increases and reduces the ineffective height of the battery, thereby increasing the volumetric energy density. It should be noted that this solution does not limit the cutting and cleaning methods; for example, laser cutting and laser cleaning can be used.

[0056] It should be further explained that the included angle θ is measured as follows: The top sealing edge area of ​​the battery is cut along the extension direction of the tab 2, and a cross-sectional sample is prepared by cutting with a cutter or grinding with crystal glue. The cross-sectional sample is observed under a 3D microscope, and the specific value of the included angle θ between the first encapsulation film 121 and the second encapsulation film 122 is measured using the angle measurement tool built into the microscope software.

[0057] As attached Figure 1As shown, after laser cutting, the length of the top sealing edge 10 along the extension direction of the tab 2 satisfies the following: X is in the range of 0.7mm-2.5mm, preferably 1.0mm-1.8mm; where X is the length of the top sealing edge 10. By limiting the length range of the top sealing edge 10, the battery height is minimized and the volumetric energy density of the battery is increased by removing the large flared angle formed by the unsealed area while ensuring the battery's sealing performance.

[0058] As attached Figure 1 As shown, along the extension direction of the tab 2, the length of the inner unsealed area 11 and the length of the top sealing edge 10 satisfy the following: the range of Y / X is 0.1-0.8, where X is the length of the top sealing edge 10 and Y is the length of the inner unsealed area 11. Ensuring that the length of the inner unsealed area 11 is appropriate can, on the one hand, prevent gas from easily entering and causing the battery to bulge due to the excessive length of the inner unsealed area 11; on the other hand, it can also prevent the cell from shifting due to insufficient space and causing the battery to expand due to the insufficient length of the inner unsealed area 11; thus effectively improving the safety of the battery.

[0059] As attached Figure 2 As shown, the length of the sealing area 12 along the extension direction of the tab 2 satisfies the following: L is in the range of 0.5mm-1.8mm, preferably 0.6mm-1.5mm, where L is the length of the sealing area 12 along the extension direction of the tab 2. Keeping the length of the sealing area 12 appropriate ensures good battery sealing while ensuring that the included angle between the two layers of encapsulation film at the top edge 10 of the battery is less than 30°. This prevents external moisture from entering the cell and causing side reactions inside the battery, leading to cell failure and improving the battery production yield.

[0060] As attached Figure 8 As shown, tab 2 is provided with tab adhesive 3, and sealing area 12 includes a first segment 123. Along the second direction, the first segment 123 includes a first part 1231 and a second part 1232, with the first part 1231 wrapping around the outside of the second part 1232. The second direction in the text refers to the width direction of the battery.

[0061] In the first part 1231, the inner polymer layer 1203 of the first encapsulation film 121 and the inner polymer layer 1203 of the second encapsulation film 122 are bonded together. In the second part 1232, the inner polymer layer 1203 of the first encapsulation film 121 and / or the inner polymer layer 1203 of the second encapsulation film 122 are bonded together with the tab adhesive 3.

[0062] The sealing area 12 also includes a second segment 124. Along the extension direction of the tab 2, the second part 1232 is connected to the second segment 124, and the second direction is perpendicular to the extension direction of the tab 2. Along the extension direction of the tab 2, the distance between the edge of the second segment 124 near the second part 1232 and the end edge of the first part 1231 satisfies: |H|≤0.3mm, where |H| is the absolute difference between the edge of the second segment 124 near the second part 1232 and the end edge of the first part 1231, so that the second segment 124 and the cell maintain an appropriate distance, avoid the thermal effect generated during laser cleaning from damaging the inside of the cell, and improve the production yield of the battery.

[0063] Specifically, along the extension direction of the tab 2, the side edge of the second segment 124 near the second part 1232 may be higher than the end edge of the first part 1231; or, the side edge of the second segment 124 near the second part 1232 may be lower than the end edge of the first part 1231.

[0064] As attached Figure 8 As shown, along the extension direction of the tab 2, the length of the second segment 124 and the length of the first part 1231 satisfy the following: the ratio of Z / L0 is in the range of 10%-70%; where Z is the length of the second segment 124 along the extension direction of the tab 2; and L0 is the length of the first part 1231 along the extension direction of the tab 2. By limiting the length of the second segment 124, the length of the second segment 124 is prevented from being too large, thus preventing the high heat generated during the cleaning process from causing the polymer layer of the sealing area to melt, thereby affecting the encapsulation reliability of the sealing area 12 and improving the safety of the battery.

[0065] As attached Figure 8 As shown, along the extension direction of the tab 2, the length of the second segment 124 satisfies the following: Z is in the range of 0.3mm-1mm, where Z is the length of the second segment 124 along the extension direction of the tab 2. This avoids the second segment 124 being too large, which would cause the sealing area 12 to overheat due to excessive energy consumption during the cleaning process, thus avoiding affecting the strength of the sealing area 12 at high temperatures and ensuring the sealing reliability of the sealing area 12. At the same time, it is also necessary to ensure that the overall height of the battery cannot be effectively reduced if the second segment 124 is too small.

[0066] After laser cutting the top sealing edge 10, since the tab 2 of the top sealing edge 10 cannot be cut, the tab 2 position is laser cleaned. After laser cleaning, in one embodiment, the second segment 124 can be understood as the cleaning segment. The second segment 124 includes a first region 1241, a second region 1242, and a third region 1243 arranged sequentially along the extension direction of the tab 2, as shown in the attached figure. Figure 5 As shown; or, the second segment 124 includes a second region 1242 and a third region 1243 arranged sequentially along the extension direction of the tab 2, as shown in the attached figure. Figure 6 As shown. It should be noted that, in one embodiment, the third region 1243 can be approximately considered as the area of ​​tab adhesive that is not bonded to the inner polymer layer 1203. The thickness of the third region 1243 can be understood as the thickness of the tab adhesive on one side of the tab 2. Of course, in another embodiment, the third region 1243 may include not only the area of ​​tab adhesive that is not bonded to the inner polymer layer 1203, but also residual inner polymer layer. The residual inner polymer layer belongs to the inner polymer layer 1203 of the first encapsulation film 121 and / or the second encapsulation film 122 of the sealing region 12. The residual inner polymer layer included in the third region 1243 is bonded and fused together with the tab adhesive layer on the tab 2. However, since this region is small, the thickness of the third region 1243 can be approximately understood as the thickness of the tab adhesive on one side of the tab 2 that is not bonded to the inner polymer layer.

[0067] As attached Figure 8 As shown, along the extension direction of the tab, the first region 1241 is connected to the second part 1232; along the third direction, the thickness of the second region 1242 is greater than the thickness of the first region 1241, and the thickness of the second region 1242 is greater than the thickness of the third region 1243. In one embodiment, during battery encapsulation, the tab adhesive 3 and the inner polymer layer 1203 of the encapsulation film need to be heated and pressed together by the sealing head to achieve a certain temperature. During the hot pressing process, overflow may occur in the area where the tab adhesive 3 and the inner polymer layer 1203 of the encapsulation film are bonded. Therefore, the sealing area 12 of the top sealing edge 10 includes the fusion area where the tab adhesive layer and the inner polymer layer of the encapsulation film are bonded together, as well as the overflow area generated after fusion. The first area 1241 can be understood as the fusion area, and the second area 1242 can be understood as the overflow area. In the overflow area, the adhesive layer is squeezed and accumulated in a region with a larger thickness. Therefore, the thickness of the second area 1242 is greater than the thickness of the first area 1241. That is, the thickest part of the overflow area is greater than the thickest part of the fusion area. It should be further noted that the area of ​​the cleaning section can be flexibly set according to the actual situation, and may include or exclude the first area 1241.

[0068] And / or, in the extension direction of the tab 2, the length of the third region 1243 is: A ≤ 0.2 mm, where A is the length of the third region 1243 in the extension direction of the tab 2; and / or, in the extension direction of the tab 2, the length of the second region 1242 is: B ≤ 0.2 mm, where B is the length of the second region 1242 in the extension direction of the tab 2. By limiting the lengths of the second region 1242 and the third region 1243, the appropriate length of the second segment 124 is ensured.

[0069] As attached Figure 4As shown, the portion of the tab 2 extending outside the sealing area 12 is provided with tab adhesive 3 that does not contact the inner polymer layer 1203 of the first encapsulation film 121 and / or the second encapsulation film 122. The tab adhesive 3 is connected to the second segment 124. Along the third direction, the thickness of the second region 1242 and the thickness of the tab adhesive 3 satisfy the following condition: C ≥ D, where C is the thickness of the second region 1242 and D is the thickness of the tab adhesive 3 that does not contact the inner polymer layer 1203 of the first encapsulation film 121 and / or the second encapsulation film 122 on the portion of the tab 2 extending outside the sealing area 12. And / or, along the third direction, the thickness of the second region 1242 satisfies the following condition: C is in the range of 0.05mm-1mm, preferably 0.08mm-0.8mm; where C is the thickness of the second region 1242. To ensure that tab 2 retains sufficient strength after bending, excessive cleaning should be avoided to prevent the base of tab 2 from exposing itself to the top seal edge 10, thus preventing a short circuit between tab 2 and the top seal edge 10 and ensuring high battery safety. The third direction mentioned in this text refers to the thickness direction of tab 2, which is perpendicular to the first and second directions.

[0070] As attached Figure 8 As shown, in the second direction, the absolute difference between the length of the second segment 124 and the length of the second part 1232 satisfies: |L1-L2|<0.2mm; where L1 is the length of the second segment 124 in the second direction, and L2 is the length of the second part 1232 in the second direction; the length of the tab 2 exposed outside the second segment 124 is sufficient to ensure that the tab 2 can be effectively bent during packaging; and the second segment 124 has sufficient length to provide stable support for the root of the tab 2.

[0071] As attached Figure 3 As shown, due to the thermal effect of laser cutting, during laser processing, the outer protective layer 1201 of the first encapsulation film 121 and the outer protective layer 1201 of the second encapsulation film 122 will shrink inward due to heat. A first metal layer exposed area 125 is provided at the end of the metal layer 1202 of the first encapsulation film 121 facing the outer protective layer 1201; and / or, a second metal layer exposed area 126 is provided at the end of the metal layer 1202 of the second encapsulation film 122 facing the outer protective layer 1201. This directly exposes the ends of the metal layers 1202 of the first encapsulation film 121 and the second encapsulation film 122, forming exposed metal layer areas. Since the metal layer has a visible light reflectance of 80%~90%, while the remaining unsealed area has a visible light reflectance of <70%, the exposed metal layer area 1204 has a significant difference in brightness compared to the remaining unsealed area 12, as shown in the attached figure. Figure 4 As shown, the exposed metal layer area 1204 makes the boundary of the top sealing edge 10 more obvious, which is beneficial for edge finding and positioning in subsequent processing. It also helps to ensure that the position of the heat spreader in the area of ​​the top sealing edge of the battery is appropriate, reduces the leakage of the heat spreader, and improves the production yield.

[0072] In the extending direction of the tab 2, the first metal layer exposed area 125 and the second metal layer exposed area 126 satisfy: L4 < L3, and / or, L4 < 100 um; where L3 is the length of the first metal layer exposed area 125 in the extending direction of the tab 2; L4 is the length of the second metal layer exposed area 126 in the extending direction of the tab 2; ensuring that the lengths of both the first metal layer exposed area 125 and the second metal layer exposed area 126 are appropriate, and avoiding the influence of laser processing on the appearance of the battery.

[0073] As atta Figure 3 As shown, during laser cutting, affected by the laser thermal effect, a third metal layer exposed area 127 is recessed at one end of the sealing area 12 away from the unsealed area 11, so that the end portions of the metal layer 1202 of the first encapsulation film 121 facing the inner polymer layer 1203 and the end portions of the metal layer 1202 of the second encapsulation film 122 facing the inner polymer layer 1203 of the inner polymer layer 1203 are both exposed.

[0074] The third metal layer exposed area 127 is the metal layer exposed area provided at the end portion of the metal layer 1202 of the first encapsulation film 121 facing the inner polymer layer 1203 of the first encapsulation film 121; and / or, the third metal layer exposed area 127 is the metal layer exposed area provided at the end portion of the metal layer 1202 of the second encapsulation film 121 facing the inner polymer layer 1203; that is, L5 can specifically be the distance between the end of the third metal layer exposed area 127 and the end of the sealing area 12 away from the unsealed area 11.

[0075] In the extending direction of the tab 2, the third metal layer exposed area 127 satisfies: L5 < 50 um; where L5 is the length of the third metal layer exposed area 127 in the extending direction of the tab 2, ensuring that the length of the third metal layer exposed area 127 is appropriate, which can effectively isolate the moisture outside the battery, and can also avoid excessive inward depression of the polymer layer 1203 and the tab adhesive layer of the sealing area 12 caused by the excessive third metal layer exposed area 127, thereby reducing the packaging reliability.

[0076] As atta Figure 9 As shown, burrs 128 are provided on the first metal layer exposed area 125, the second metal layer exposed area 126 and / or the third metal layer exposed area 127; the width of the burrs 128 in the second direction: M1 < 20 um, where M1 is the width of the burrs 128 in the second direction; the height of the burrs 128 in the extending direction of the tab 2: M2 < 50 um, where M2 is the height of the burrs 128 in the extending direction of the tab 2, ensuring that the height of the burrs 128 is appropriate, avoiding the burrs 128 piercing the insulating paper and causing a short circuit inside the battery cell, and improving the safety of the battery.

[0077] As a preferred embodiment, taking a certain wound battery cell as an example, its preparation process is as follows:

[0078] (1) Preparation of positive electrode sheet: The positive electrode active material, binder polyvinylidene fluoride and conductive agent carbon black are mixed in a specific ratio according to the mass percentage, and an appropriate amount of N-methylpyrrolidone is added as a solvent. The mixture is stirred evenly to make an electrode slurry. The prepared positive electrode slurry is evenly coated on aluminum foil and rolled and cut to form a positive electrode sheet.

[0079] (2) Preparation of negative electrode sheet: The negative electrode active material, styrene-butadiene rubber and conductive carbon black are mixed evenly in a specific ratio, and deionized water is added to make a negative electrode active coating slurry. The above negative electrode active coating slurry is evenly coated on both sides of the copper foil, and after drying and compaction by a roller press, a negative electrode sheet is obtained.

[0080] (3) Battery preparation: The positive electrode tab and the negative electrode tab are welded into the positive electrode sheet and the negative electrode sheet in step (1) and step (2) respectively. The positive electrode tab and the negative electrode tab are provided with tab adhesive on both sides. The positive electrode sheet, the polyethylene separator and the negative electrode sheet prepared in step (1) are wound together to form a core. The battery cell is placed in the encapsulation film for primary encapsulation. Then, after electrolyte injection, the battery is formed, resealed, sorted and OCV tested to obtain the battery.

[0081] (4) Laser cutting and cleaning: The battery prepared in step (3) is cut and cleaned at the top sealing edge 10, as shown in the attached figure. Figure 7 As shown. The formula for calculating the battery volumetric energy density is as follows: Energy density = Battery capacity * Voltage / Battery volume.

[0082] Comparative Example: The battery prepared in step (3) was not subjected to laser cutting and cleaning. Before cutting, the size of the top seal 10 was 2.7 mm, of which the length of the inner unsealed area 11 of the top seal edge 10 was 0.5 mm; and the angle θ between the first encapsulation film 121 and the second encapsulation film 122 at the outer unsealed area of ​​the top seal edge 10 was 35°. During the process, the battery height was 90 mm, the battery width was 54 mm, the battery thickness was 5.9 mm, the battery capacity was 4540 mAh, the battery voltage system was 4.4 V, and the battery volumetric energy density was 696.66 Wh / L.

[0083] Example: The unsealed areas of the first encapsulation film 121 and the second encapsulation film 122 of the battery prepared in step (3) are cut and cleaned. After cutting, the unsealed area of ​​the top sealing edge 10 in the battery of the example is removed, and the length Y of the inner unsealed area 11 of the top sealing edge 10 is 0.5 mm; the length of the sealing area 12 is 1.4 mm; after cutting and cleaning, the angle θ between the first encapsulation film 121 and the second encapsulation film 122 at the position of the top sealing edge 10 is 10°, and the exposed areas of the first metal layer 125 and the second metal layer are exposed. The dimensions of the exposed area 126 of the metal layer and the exposed area 127 of the third metal layer are 77um, 35um, and 10um, respectively; along the extension direction of the tab 2, the dimension of the second segment 124 is 0.8mm; along the width direction of the cell, the length of the second segment 124 is equal to the length of the tab adhesive 3, and the thickness B of the second area 1242 is 120um; the part of the tab 2 extending out of the sealing area 12 is provided with a tab adhesive 3 with a thickness of 80um that does not contact the inner polymer layer 1203 of the first encapsulation film 121 and / or the second encapsulation film 122;

[0084] In this embodiment, the included angle θ between the first encapsulation film 121 and the second encapsulation film 122 on the top sealing edge 10 is significantly smaller than that in the comparative example. Therefore, the tension of the first encapsulation film 121 and the second encapsulation film 122 on the adhesive tape set on the top sealing edge 10 during PACK encapsulation can be reduced. Compared to the battery PACK encapsulation in the comparative example, the battery PACK encapsulation yield in this embodiment is improved by 10%. After cleaning by the cutting machine, the top sealing width of the battery is reduced to 1.9 mm, and the battery height is reduced to 89.2 mm. After cutting, the battery volumetric energy density increases to 702.91 Wh / L. Compared to the battery in the comparative example, the volumetric energy density of the battery increases by 0.9% after cutting.

[0085] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0086] This article uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A battery, characterized by, The battery cell body includes a tab (2), and a package (1) encapsulating the battery cell body; The package (1) includes a top sealing edge (10), and the tab (2) extends out of the package (1) in a first direction from the top sealing edge (10); the top sealing edge (10) includes an inner unsealed area (11) and a sealing area (12) outside the inner unsealed area (11) in the direction of the tab (2); The package (1) includes oppositely arranged first and second encapsulation films (121 and 122), and each of the first and second encapsulation films (121 and 122) includes an outer protective layer (1201), an inner polymer layer (1203), and a metal layer (1202) between the outer protective layer (1201) and the inner polymer layer (1203); In the direction of the tab (2), the included angle θ between the first and second encapsulation films (121 and 122) at the end of the top sealing edge (10) satisfies θ < 30°.

2. The battery of claim 1, wherein, In the direction of the tab (2), the length of the top sealing edge (10) satisfies X in the range of 0.7 mm-2.5 mm; wherein X is the length of the top sealing edge (10).

3. The battery of claim 2, wherein, In the direction of the tab (2), the length of the top sealing edge (10) satisfies X in the range of 1.0 mm-1.8 mm; wherein X is the length of the top sealing edge (10).

4. The battery of claim 2, wherein, In the direction of the tab (2), the length of the top sealing edge (10) satisfies X in the range of 1.0 mm-1.8 mm; wherein X is the length of the top sealing edge (10).

5. The battery of claim 2, wherein, In the direction of the tab (2), the length of the top sealing edge (10) satisfies X in the range of 1.0 mm-1.8 mm; wherein X is the length of the top sealing edge (10).

6. The battery of claim 5, wherein, In the direction of the tab (2), the length of the top sealing edge (10) satisfies X in the range of 1.0 mm-1.8 mm; wherein X is the length of the top sealing edge (10). In the direction of the tab (2), the length of the top sealing edge (10) satisfies X in the range of 1.0 mm-1.8 mm; wherein X is the length of the top sealing edge (10).

7. The battery according to any one of claims 1 to 6, characterized in that, The tab (2) is provided with a tab adhesive (3), the sealing area (12) includes a first section (123), along a second direction, the first section (123) includes a first part (1231) and a second part (1232), in the first part (1231), the inner polymer layer (1203) of the first packaging film (121) and the inner polymer layer (1203) of the second packaging film (122) are bonded, in the second part (1232), the inner polymer layer (1203) of the first packaging film (121) and / or the inner polymer layer (1203) of the second packaging film (122) are bonded with the tab adhesive (3); the sealing area (12) further includes a second section (124), along the extension direction of the tab (2), the second part (1232) is connected with the second section (124), the second direction is perpendicular to the extension direction of the tab (2); In the extension direction of the tab (2), the distance between the side edge of the second section (124) close to the second part (1232) and the end edge of the first part (1231) satisfies: |H|≤0.3mm, wherein |H| is the absolute difference between the side edge of the second section (124) close to the second part (1232) and the end edge of the first part (1231).

8. The battery of claim 7, wherein, In the extension direction of the tab (2), the length of the second section (124) and the length of the first part (1231) satisfy: the ratio of Z / L0 ranges from 10% to 70%; wherein Z is the length of the second section (124) in the extension direction of the tab (2); L0 is the length of the first part (1231) in the extension direction of the tab (2); And / or, in the extension direction of the tab (2), the length of the second section (124) satisfies: Z ranges from 0.3mm to 1mm, wherein Z is the length of the second section (124) in the extension direction of the tab (2).

9. The battery of claim 8, wherein, The second section (124) includes a first area (1241), a second area (1242) and a third area (1243) arranged in sequence along the extension direction of the tab (2); or, the second section (124) includes a second area (1242) and a third area (1243) arranged in sequence along the extension direction of the tab (2); Along the extension direction of the tab (2), the first area (1241) is connected with the second part (1232); along a third direction, the thickness of the second area (1242) is greater than the thickness of the first area (1241), and / or the thickness of the second area (1242) is greater than the thickness of the third area (1243); And / or, in the extension direction of the tab (2), the length of the third area (1243) is: A≤0.2mm, wherein A is the length of the third area (1243) in the extension direction of the tab (2). And / or, in the extending direction of the tab (2), the length of the second area (1242): B≤0.2mm, wherein B is the length of the second area (1242) in the extending direction of the tab (2).

10. The battery of claim 9, wherein, The part of the tab (2) extending out of the sealing area (12) is provided with a tab adhesive (3) not in contact with the inner polymer layer (1203) of the first packaging film (121) and / or the second packaging film (122), the tab adhesive (3) being connected with the second section (124); In the third direction, the thickness of the second area (1242) and the thickness of the tab adhesive (3) satisfy: C≥D, wherein C is the thickness of the second area (1242), and D is the thickness of the part of the tab (2) extending out of the sealing area (12) and provided with the tab adhesive (3) not in contact with the inner polymer layer (1203) of the first packaging film (121) and / or the second packaging film (122); And / or, in the third direction, the thickness of the second area (1242) satisfies: C is in the range of 0.05mm-1mm; wherein C is the thickness of the second area (1242).

11. The battery of claim 10, wherein, In the third direction, the thickness of the second area (1242) satisfies: C is in the range of 0.08mm-0.8mm; wherein C is the thickness of the second area (1242).

12. The battery of claim 10, wherein, In the second direction, the absolute difference between the length of the second section (124) and the length of the second part (1232) satisfies: |L1-L2|<0.2mm; wherein L1 is the length of the second section (124) in the second direction, and L2 is the length of the second part (1232) in the second direction.

13. The battery of claim 7, wherein, The side end of the metal layer (1202) of the first packaging film (121) towards the outer protective layer (1201) is provided with a first metal layer exposed area (125); And / or, the side end of the metal layer (1202) of the second packaging film (122) towards the outer protective layer (1201) is provided with a second metal layer exposed area (126); In the extending direction of the tab (2), the first metal layer exposed area (125) and the second metal layer exposed area (126) satisfy: L4<L3; wherein L3 is the length of the first metal layer exposed area (125) in the extending direction of the tab (2); and L4 is the length of the second metal layer exposed area (126) in the extending direction of the tab (2); And / or, the length of the second metal layer exposed area (126) in the extending direction of the tab (2) satisfies: L4<100um, wherein L4 is the length of the second metal layer exposed area (126) in the extending direction of the tab (2).

14. The battery of claim 13, wherein, The end of the sealing area (12) away from the inner unsealed area (11) is provided with a third metal layer exposed area (127); In the extension direction of the tab (2), the third metal layer exposed area (127) satisfies: L5<50um; wherein L5 is the length of the third metal layer exposed area (127) in the extension direction of the tab (2).

15. The battery of claim 14, wherein, The first metal layer exposed area (125) and / or the second metal layer exposed area (126) and / or the third metal layer exposed area (127) is provided with a burr (128); The width of the burr (128) along the second direction: M1<20um, wherein M1 is the width of the burr (128) along the second direction; And / or, the height of the burr (128) along the extension direction of the tab (2): M2<50um, wherein M2 is the height of the burr (128) along the extension direction of the tab (2).

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