Battery

Abstract

The utility model provides a battery which comprises a battery cell body and a packaging body for packaging the battery cell body, the packaging body comprises a top sealing edge, and the top sealing edge comprises a sealing area and an outer unsealed area arranged on the outer side of the sealing area in the extending direction of a 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 end part of the metal layer of the first packaging film in the outer unsealed region respectively exceeds the end part of the outer protective layer of the first packaging film and the end part of the inner polymer layer of the first packaging film in the extension direction of the tab to form a metal layer exposed region; and / or, along the extension direction of the tabs, the end part of the metal layer of the second packaging film in the outer unsealed region respectively exceeds the end parts of the outer protective layer of the second packaging film and the inner polymer layer of the second packaging film to form a metal layer exposed region, so that the overall height of the battery is reduced, and the volume energy density and the production yield of the battery are 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] Existing encapsulation films are generally three-layered structures consisting of a protective layer, a metal layer, and a polymer layer. During lithium battery packing, to prevent short circuits caused by contact between the metal layer of the top-sealing encapsulation film and the tabs or protection board, a protective film is typically wrapped around the top-sealing encapsulation film to cover it. During the adhesive application process, testing instruments are needed to identify and locate the areas on the battery where adhesive needs to be applied. However, the protective layer on the surface of the encapsulation film has low reflectivity to the light emitted by the testing instruments. Under this light, the battery head boundary is not clearly visible, making positioning during the encapsulation process difficult and prone to defects such as misalignment or incomplete application, resulting in yield losses. Utility Model Content

[0004] The purpose of this invention is to provide a battery in which both the end of the first encapsulation film and the end of the second encapsulation film in the unsealed area have exposed metal layers, making the boundary of the top seal edge more obvious, facilitating edge finding and positioning, reducing issues such as misaligned or improperly positioned adhesive tape, and effectively improving 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 from the top seal edge in a first direction beyond the top seal edge; the top seal edge includes a sealing area and an unsealed area located outside the sealing area in the direction of extension of the electrode tab.

[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 end of the metal layer of the first encapsulation film in the unsealed area extends beyond the end of the outer protective layer of the first encapsulation film and the end of the inner polymer layer of the first encapsulation film to form an exposed metal layer area.

[0009] And / or, along the direction in which the tab extends, the end portion of the metal layer of the second encapsulation film in the outer unsealed area respectively exceeds the end portion of the outer protective layer of the second encapsulation film and the end portion of the inner polymer layer of the second encapsulation film to form a metal layer exposed area.

[0010] In one embodiment, the length of the outer unsealed area satisfies: 0.2mm≤L≤0.5mm, where L is the length of the outer unsealed area along the direction in which the tab extends.

[0011] In one embodiment, the length of the outer unsealed area and the thickness of the first encapsulation film or the second encapsulation film along the second direction satisfy: 2T<L<6T, where L is the length of the outer unsealed area along the direction in which the tab 2 extends, and T is the thickness of the first encapsulation film or the second encapsulation film along the second direction.

[0012] And / or, the thickness of the first encapsulation film or the second encapsulation film along the second direction satisfies: 70um≤T≤160um, where T is the thickness of the first encapsulation film or the second encapsulation film along the second direction.

[0013] In one embodiment, the metal layer exposed area includes a first metal layer exposed area and a second metal layer exposed area respectively arranged on the two sides of the metal layer, the first metal layer exposed area is arranged on the side of the metal layer attached to the outer protective layer, and the second metal layer exposed area is arranged on the side of the metal layer attached to the inner polymer layer.

[0014] The length of the first metal layer exposed area satisfies: 50um≤L1≤150um, where L1 is the length of the first metal layer exposed area.

[0015] And / or,

[0016] The length of the second metal layer exposed area satisfies: L2<L1, and / or, 20um≤L2<50um, where L1 is the length of the first metal layer exposed area, and L2 is the length of the second metal layer exposed area.

[0017] In one embodiment, the sealing area includes a first part close to the end of the outer unsealed area along the direction in which the tab extends.

[0018] Both the first encapsulation film and the second encapsulation film are bonded with the first part, and the first encapsulation film and the second encapsulation film of the outer unsealed area each include an unsealed section, one end of the unsealed section being connected to the first part along the extension direction of the first encapsulation film or the second encapsulation film.

[0019] The extension length of the unsealed section and the single-sided thickness of the first part along the second direction satisfy: L3 / H1<0.8, where L3 is the extension length of the unsealed section along the extension direction of the first encapsulation film or the second encapsulation film, and H1 is the single-sided thickness of the first part along the second direction.

[0020] In one embodiment, the first encapsulation film and the second encapsulation film of the top seal edge end portion extend in a second direction away from the direction in which the tab extends; and the included angle formed between the first encapsulation film and the second encapsulation film of the top seal edge end portion satisfies: 30°≤θ≤50°, wherein θ is the included angle formed between the first encapsulation film and the second encapsulation film of the top seal edge end portion.

[0021] In one embodiment, the tab is covered with tab adhesive that is not bonded to the outer unsealed area, and the projection length of the unsealed section on the tab adhesive and the length of the tab adhesive in the extension direction of the tab satisfy: L4>L5, wherein L4 is the projection length of the unsealed section on the tab adhesive, and L5 is the length of the tab adhesive in the extension direction of the tab.

[0022] In one embodiment, the exposed area of the metal layer on the side of the inner polymer layer forms a bare projection area on the tab adhesive, the tab adhesive is provided with a non-contact area that does not contact the inner polymer layer, and the bare projection area is completely within the non-contact area.

[0023] In one embodiment, the length of the bare projection area and the thickness of the tab adhesive in the non-contact area satisfy: L6<T1, wherein L6 is the length of the bare projection area, and T1 is the thickness of the tab adhesive in the non-contact area.

[0024] In one embodiment, the exposed area of the metal layer forms a burr;

[0025] The height of the burr in the third direction: M1<20um, wherein M1 is the height of the burr in the third direction;

[0026] The height of the burr in the extension direction of the tab: M2<50um, wherein M2 is the height of the burr in the extension direction of the tab.

[0027] Compared with the prior art, the battery in the utility model, comprising a battery core body and a packaging body for packaging the battery core body, the battery core body comprises a tab; the packaging body comprises a top seal edge, and the tab extends out of the packaging body in a first direction from the top seal edge; the top seal edge comprises a seal area and an outer unsealed area arranged outside the seal area in the direction in which the tab extends; the packaging body comprises oppositely arranged first and second encapsulation films, and the first and second encapsulation films each comprise an outer protective layer, an inner polymer layer, and a metal layer between the outer protective layer and the inner polymer layer.

[0028] The end of the metal layer of the first encapsulation film in the outer unsealed area exceeds the end of the outer protective layer of the first encapsulation film and / or the end of the inner polymer layer to form a metal layer exposed area along the extension direction of the tab; and / or, the end of the metal layer of the second encapsulation film in the outer unsealed area exceeds the end of the outer protective layer of the second encapsulation film along the extension direction of the tab and / or the end of the inner polymer layer to form a metal layer exposed area along the extension direction of the tab. The setting of the metal layer exposed area can improve the efficiency of the top sealing edge overcoat waistcoat glue and the yield of the overcoat glue during the battery PACK process, because the reflectivity of the metal layer exposed area to visible light is 80% to 90%, and the reflectivity of the rest of the outer unsealed area of the top sealing edge to visible light is less than 70%. The light and dark difference between the metal layer exposed area and the rest of the outer unsealed area is large, the metal layer exposed area makes the boundary of the top sealing edge more obvious, which is beneficial to edge finding and positioning in the subsequent processing process, and is beneficial to ensuring that the position of the waistcoat glue in the area of the top sealing edge of the battery is appropriate, reducing the situation that the waistcoat glue is skewed or improperly positioned, and improving the production yield. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and those skilled in the art can obtain other drawings according to the provided drawings without creative labor.

[0030] Figure 1 The side view of the top sealing edge of the battery provided by the embodiments of the present application;

[0031] Figure 2 The front view of Figure 1 ;

[0032] Figure 3 The structure diagram of the top sealing edge in Figure 1 ;

[0033] Figure 4 The reflection contrast diagram of the metal layer exposed area and the rest of the outer unsealed area in Figure 1 ;

[0034] Figure 5 The structure diagram of the first encapsulation film or the second encapsulation film in Figure 1 ;

[0035] Figure 6 The schematic diagram of the first encapsulation film and the second encapsulation film in Figure 1 ;

[0036] Figure 7 The schematic diagram of the sealing area, the first encapsulation film and the second encapsulation film in Figure 1 ;

[0037] Figure 8 for Figure 1 Fig. 2 is a schematic view of the sealing area, the tab, the tab adhesive and the first encapsulation film;

[0038] Figure 9 for Figure 7 Fig. 3 is a schematic view of the connection between the tab and the circuit board;

[0039] Figure 10 for Figure 7 Fig. 4 is another schematic view of the connection between the tab and the circuit board;

[0040] Figure 11 Fig. 5 is a schematic view of the burr of the metal layer exposed area.

[0041] The reference signs are as follows:

[0042] The encapsulation body 1, the tab 2, the tab adhesive 3 and the circuit board 4;

[0043] The top sealing edge 10, the sealing area 11, the outer unsealed area 12 and the inner unsealed area 13;

[0044] The first part 110;

[0045] The waistcoat adhesive paper 120, the first encapsulation film 121 and the second encapsulation film 122;

[0046] The outer protective layer 1201, the metal layer 1202, the inner polymer layer 1203, the metal layer exposed area 1204 and the unsealed section 1205;

[0047] The first metal layer exposed area 1204-1, the second metal layer exposed area 1204-2 and the burr 1204-3;

[0048] The exposed projection area 31 and the non-contact area 32. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0050] In order to enable those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0051] The embodiments of the present application provide an electric core, as shown in Fig. 1. Figure 1 and 2As shown, the battery top sealing edge 10 is encapsulated by two layers of aluminum plastic film, the sealing area 11 includes two layers of aluminum plastic film, the inner polymer layer 1203 of the two layers of aluminum plastic film is fused and partially adheres to the tab adhesive 3 on the tab 2, ensuring that the battery has good sealing performance. It should be noted that the tab adhesive 3 can also be a polypropylene layer.

[0052] The encapsulating body 1 includes a first encapsulating film 121 and a second encapsulating film 122 arranged opposite to each other, both the first encapsulating film 121 and the second encapsulating film 122 include 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. Among them, the outer protective layer 1201 can be a nylon layer, the metal layer 1202 can be an aluminum foil layer, and the inner polymer layer 1203 can be a polypropylene layer. Both the first encapsulating film 121 and the second encapsulating film 122 are single-layer aluminum plastic films.

[0053] As an embodiment, as shown in the accompanying drawings, Figure 3 As shown, the top sealing edge 10 is encapsulated by two layers of aluminum plastic film, the sealing area 11 includes two layers of aluminum plastic film, the inner polymer layer 1203 of the two layers of aluminum plastic film is fused and partially adheres to the tab adhesive 3 on the tab 2, ensuring that the battery has good sealing performance. It should be noted that the tab adhesive 3 can also be a polypropylene layer.

[0054] Along the extension direction of the tab 2, the end of the metal layer 1202 of the first encapsulating film 121 in the outer unsealed area 12 respectively exceeds the end of the outer protective layer 1201 of the first encapsulating film 121 and the end of the inner polymer layer 1203 of the first encapsulating film 121 to form a metal layer exposed area 1204; and / or, along the extension direction of the tab 2, the end of the metal layer 1202 of the second encapsulating film 122 in the outer unsealed area 12 respectively exceeds the end of the outer protective layer 1201 of the second encapsulating film 122 and the end of the inner polymer layer 1203 of the second encapsulating film 122 to form a metal layer exposed area 1204.

[0055] In an embodiment of the present application, the outer unsealed area 12 of the battery top sealing edge 10 is subjected to cutting treatment, and the cutting method is not limited, for example, laser cutting can be used. After laser cutting processing, the end of the metal layer 1202 of the first encapsulating film 121 and the second encapsulating film 122 of the battery top sealing edge 10 is exposed, so that the end of the metal layer 1202 respectively exceeds the end of the outer protective layer 1201 and the inner polymer layer 1203, and the metal layer 1202 is exposed on both sides of the end to form a metal layer exposed area 1204, which can improve the efficiency and yield of the top sealing edge covering the jacket adhesive during the battery PACK process. As shown in the accompanying drawings, Figure 5 The metal layer exposed area 1204 is an aluminum leakage area.

[0056] On the one hand, after the top sealing edge 10 of the battery is cut, the exposed area 1204 of the metal layer becomes shorter, thus reducing the length of the unsealed area 12 of the top sealing edge 10, thereby lowering the overall height of the battery and effectively reducing its total height, thus increasing its volumetric energy density. On the other hand, since the metal layer 1202 has a visible light reflectance of 80%~90%, while the remaining part of the unsealed area 12 has a visible light reflectance of <70%, the exposed area 1204 of the metal layer has a significant difference in brightness compared to the remaining part of the 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, reducing the possibility of the heat spreader being misaligned or improperly positioned, and improving the production yield.

[0057] It should be noted that reflectance can be measured by methods such as the reflected light intensity ratio method, the reflectance spectrum method, the reflection angle method, and the reflectance ratio method.

[0058] Apart from sealed zone 11 and unsealed zone 12, see attached. Figure 1 and 2 As shown, the top sealing edge 10 also has an inner unsealed area 13, which is located on the side of the sealing area 11 away from the outer unsealed area 12.

[0059] In some embodiments, as shown in the appendix Figure 3 As shown, the length of the unsealed area 12 satisfies: 0.2mm ≤ L ≤ 0.5mm, where L is the length of the unsealed area 12 along the extension direction of the tab 2. This avoids damage to the sealing area 11 when cutting the unsealed area 12 of the top sealing edge 10 due to the unsealed area 12 being too small, which would also generate heat during laser cutting and affect the encapsulation reliability of the sealing area 11. On the other hand, it also avoids increasing the overall ineffective height of the battery due to the unsealed area 12 being too long, which would reduce the volumetric energy density of the battery. Ensuring that the length of the unsealed area 12 is appropriate makes it easy to capture the exposed metal layer area 1204 during edge finding and positioning, effectively improving the production yield of the battery. It should be noted that the length of the unsealed area 12 refers to the distance between the end of the sealing area 11 and the end of the unsealed area 12 in the extension direction of the tab 2.

[0060] In some embodiments, as shown in the appendix Figure 3As shown, the length of the outer unsealed area 12 and the thickness of the first encapsulation film 121 or the second encapsulation film 122 in the second direction satisfy: 2T < L < 6T, where L is the length of the outer unsealed area 12 in the direction of the tab 2, and T is the thickness of the first encapsulation film 121 or the second encapsulation film 122 in the second direction; and / or, the thickness of the first encapsulation film 121 or the second encapsulation film 122 in the second direction satisfies: 70um ≤ T ≤ 160um, where T is the thickness of the first encapsulation film 121 or the second encapsulation film 122 in the second direction. In this way, heat generated in the process of forming the metal layer exposed area 1204 by laser cutting can be prevented from being conducted to the sealing area 11 of the top sealing edge 10, so as to reduce the bonding force between the inner polymer layer 1203 of the sealing area 11 or the inner polymer layer 1203 and the tab adhesive 3 on the tab 2, and ensure more reliable encapsulation of the sealing area 11. The second direction in the text refers to the thickness direction of the first encapsulation film 121 or the second encapsulation film 122, that is, the thickness direction of the battery, and the second direction is perpendicular to the first direction.

[0061] As shown in the accompanying drawings, Figure 5 As shown, the metal layer exposed area 1204 includes a first metal layer exposed area 1204-1 and a second metal layer exposed area 1204-2 respectively arranged on the two sides of the metal layer 1202, the first metal layer exposed area 1204-1 is arranged on the side of the metal layer 1202 attached to the outer protective layer 1201; and the second metal layer exposed area 1204-2 is arranged on the side of the metal layer 1202 attached to the inner polymer layer 1203. It should be noted that the metal layer exposed area 1204 in the present application can be formed by laser cutting, or other methods, as long as the effect of the present application can be achieved, which is not limited herein.

[0062] The length of the exposed area 1204-1 of the first metal layer satisfies: 50um ≤ L1 ≤ 150um, where L1 is the length of the exposed area 1204-1 of the first metal layer; this can avoid the situation where the exposed area 1204-1 of the first metal layer is too small, resulting in an unclear boundary contour of the battery cell and excessive difficulty in edge searching and positioning; at the same time, it can also avoid the situation where the exposed area 1204-1 of the first metal layer is too large, leading to a large contact between the exposed area of the metal layer and other components of the battery, increasing the risk of corrosion or short circuit. For example, the exposed area 1204-1 of the first metal layer may come into contact with the negative electrode tab of the battery and cause a short circuit, resulting in battery failure. It can also avoid the situation where the exposed area 1204-1 of the first metal layer is too large and affects the appearance and cutting consistency of the battery cell. And / or, the length of the exposed area 1204-2 of the second metal layer satisfies: L2 < L1, and / or, 20 ≤ L2 < 50um, where L1 is the length of the exposed area 1204-1 of the first metal layer and L2 is the length of the exposed area 1204-2 of the second metal layer. On the one hand, L2 is the length of the exposed area 1204-2 of the metal layer on the side where the metal layer 1202 is attached to the inner polymer layer 1203. The exposed area 1204-2 on this side has a greater risk of direct contact with the electrode tab 2. Defining L2 < L1 can尽可能 reduce the length of the exposed area 1204-2 of the metal layer on the side of the inner polymer layer 1203 and reduce the risk of its contact with the electrode tab 2. On the other hand, if L2 is too large, the heat generated during cutting will cause the inner polymer layer 1203 to melt, causing the inner polymer layer 1203 to accumulate at the edge of the outer unsealed area 12 and reducing the thickness flatness of the edge of the top seal 10, resulting in poor appearance of the battery cell. Therefore, it is necessary to ensure that the length of the exposed area 1204-2 of the second metal layer is appropriate.

[0063] As shown in the Figure 7 attachment, the sealing area 11 includes a first part 110 along the extending direction of the electrode tab 2 and close to the end of the outer unsealed area 12. The first encapsulation film 121 and the second encapsulation film 122 of the outer unsealed area 12 are respectively bonded to the first part 110; both the first encapsulation film 121 and the second encapsulation film 122 include an unsealed segment 1205. Along the extending direction of the first encapsulation film 121 or the second encapsulation film 122, one end of the unsealed segment 1205 is connected to the first part 110.

[0064] The extension length of the unsealed section 1205 and the thickness of the first portion 110 on one side along the second direction satisfy the following condition: L3 / H1 < 0.8, where L3 is the extension length of the unsealed section 1205 in the extension direction of the first encapsulation film 121 or the second encapsulation film 122, and H1 is the thickness of the first portion 110 on one side along the second direction. This arrangement prevents the exposed metal layer area 1204 from short-circuiting due to bending and contact with the tab 2, thereby improving battery safety. It can be understood that the unsealed section 1205 belongs to the outer unsealed area, and the extension direction of the first encapsulation film 121 or the second encapsulation film 122 can form a certain angle with the extension direction of the tab 2. That is, the angle formed by the extension direction of the first encapsulation film 121 or the second encapsulation film 122 and the extension direction of the tab 2 can be half of the angle θ formed between the first encapsulation film 121 and the second encapsulation film 122 at the end of the top sealing edge 10.

[0065] It should be noted that due to the problem of adhesive overflow at the end of the sealing area 11, the outer contour of the first part 110 is an irregular surface, including a raised section extending towards the first encapsulation film 121 or the second encapsulation film 122 and a recessed section smoothly connected to both sides of the raised section. The bonding points of the first encapsulation film 121 and the second encapsulation film 122 with the first part 110 are located at the highest point of the raised section. Therefore, H1 in the text is the maximum single-sided thickness of the first part 110 along the second direction.

[0066] As attached Figure 6 As shown, the first encapsulation film 121 and the second encapsulation film 122 at the end of the top sealing edge 10 extend away from the tab 2 in the second direction; the included angle formed between the first encapsulation film 121 and the second encapsulation film 122 at the end of the top sealing edge 10 satisfies: 30°≤θ≤50°, where θ is the included angle formed between the first encapsulation film 121 and the second encapsulation film 122 at the end of the top sealing edge 10.

[0067] Because the unsealed area 11 of the top sealing edge 10 is not bound by the inner polymer layer 1203, it will form an opening at a certain angle. If the included angle θ is too large, after the top sealing edge 10 of the cell is covered with adhesive, the adhesive will easily be subjected to an outward force, resulting in poor adhesive coverage or even the adhesive paper not adhering tightly to the top sealing edge 10 and falling off first. In the battery PACK process, a PCB board needs to be placed on the top sealing edge 10 of the battery. If the included angle θ is too large, it will cause the PCB board located on the top sealing edge 10 of the battery to exceed the total thickness of the battery after bending. By controlling the range of the included angle θ, the phenomenon of excessive height after bending of the PCB board can be improved, and the production yield can be increased.

[0068] As attached Figure 8As shown in the drawings, the tab 2 is partially covered by the tab adhesive 3 which is not bonded to the outer unsealed area 12. The projection length of the unsealed section 1205 on the tab adhesive 3 and the length of the tab adhesive 3 along the extension direction of the tab 2 satisfy: L4>L5, where L4 is the projection length of the unsealed section 1205 on the tab adhesive 3, and L5 is the length of the tab adhesive 3 along the extension direction of the tab 2. The projection of the metal layer exposed area 1204 in the extension direction of the tab 2 can completely fall on the tab adhesive 3, avoiding short circuit caused by the contact between the metal layer exposed area 1204 and the tab 2, and improving the safety of the battery.

[0069] As shown in the drawings, Figure 7 and 8 As shown in the drawings, the metal layer exposed area 1204 on the side of the inner polymer layer 1203 forms a bare projection area 31 on the tab adhesive 3. The tab adhesive 3 is provided with a non-contact area 32 which does not contact the inner polymer layer 1203. The bare projection area 31 completely falls within the non-contact area 32, ensuring that the metal layer exposed area 1204 does not contact the tab 2 after laser cutting of the outer unsealed area 12, avoiding short circuit caused by the contact between the first packaging film 121 and / or the second packaging film 122 and the tab 2, and improving the safety of the battery.

[0070] The length of the bare projection area 31 and the thickness of the tab adhesive 3 in the non-contact area 32 satisfy: L6<T1, where L6 is the length of the bare projection area 31, and T1 is the thickness of the tab adhesive 3 in the non-contact area 32. This prevents the size of the metal layer exposed area 1204 on the side of the inner polymer layer 1203 from being too large, which would cause the tab adhesive 3 to be squeezed during the subsequent folding and sealing process, resulting in the risk of short circuit caused by the contact between the metal layer 1202 and the tab 2, and improving the safety of the battery. It should be noted that the non-contact area 32 is defined as the area formed by floating 1mm left and right from the projection point of the end of the first packaging film 121 and / or the second packaging film 122 on the tab adhesive 3.

[0071] As shown in the drawings, Figure 11 The metal layer exposed area 1204 forms a burr 1204-3. The height of the burr 1204-3 along the third direction satisfies: M1<20um, where M1 is the height of the burr 1204-3 along the third direction. The height of the burr 1204-3 along the extension direction of the tab 2 satisfies: M2<50um, where M2 is the height of the burr 1204-3 along the extension direction of the tab 2. This ensures that the height of the burr 1204-3 is appropriate, avoiding short circuit caused by the contact between the burr 1204-3 of the metal layer exposed area 1204 and the tab 2, and improving the safety of the battery. It should be noted that the third direction is perpendicular to the second direction and the first direction.

[0072] As shown in the drawings, Figure 9As shown, in one specific embodiment, the end of the tab 2 away from the sealing area 11 is bent to the top sealing edge 10 until it is electrically connected to the circuit board 4. With this structure, after the outer unsealed area 12 is laser-cut, the included angle height of the outer unsealed area 12 can be indirectly reduced, avoiding the risk of the circuit board 4 being bent due to the excessively large included angle of the outer unsealed area 12, and effectively improving the production yield.

[0073] As attached Figure 10 As shown, in another specific embodiment, the end of the tab 2 away from the sealing area 11 extends in a straight line until it is electrically connected to the circuit board 4. This structure of the tab 2 is suitable for thinner batteries. After the outer unsealed area 12 is laser-treated, the length of the outer unsealed area 12 is reduced, the overall height of the battery is reduced, and the volumetric energy density of the battery is effectively improved.

[0074] As a preferred embodiment, the battery preparation process of this invention is as follows:

[0075] (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.

[0076] (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.

[0077] (3) Battery preparation: The positive and negative tabs are welded into the positive and negative electrode sheets in steps (1) and (2) respectively. Both sides of the positive and negative tabs are provided with tab adhesive 3. The positive electrode sheet, polyethylene separator and negative electrode sheet prepared in step (1) are wound to form a core. The battery cell is placed in the encapsulation film for primary encapsulation. After electrolyte injection, the battery is formed, resealed, sorted and OCV tested to obtain the battery. The thickness of the tab adhesive 3 on one side is 80 μm, the thickness of the first encapsulation film 121 (i.e., the thickness of the encapsulation film on one side) is 88 μm, and the thickness of the sealing area 1 along the extension direction of the tab 2 near the first end of the unsealed area 12 along the second direction is 115 μm. Figure 7 (H1 in the diagram); the battery height is 89.4mm, the battery width is 33mm, the battery thickness is 5.5mm, the battery capacity is 2650mAh, the battery voltage is 4.4V, and the battery volumetric energy density is 718.59Wh / L. The volumetric energy density is calculated using the following formula: Energy density = Battery capacity * Voltage / Battery volume.

[0078] Comparative example: The battery prepared in step (3) was not cut, and the size of the unsealed area 12 was 0.7 mm.

[0079] Example: The unsealed area 12 of the battery encapsulation film prepared in step (3) is laser-cut. After laser cutting, a cutting line is formed on the tab adhesive 3. After cutting, the size of the unsealed area 12 is 0.2 mm. The projection length of the unsealed area 12 on the tab adhesive 3 is ( Figure 8 L5) is 0.1mm; along the extension direction of tab 2, the length of tab adhesive 3 in the non-sealing area ( Figure 8 L4) is 0.8 mm; along the extension direction of tab 2, the end of the metal layer 1202 of the first encapsulation film 121 in the outer unsealed area 12 extends beyond the end of the outer protective layer 1201 of the first encapsulation film 121 to form a metal layer exposed area 1204 with a size L1 of 78 μm. The end of the metal layer 1202 of the first encapsulation film 121 in the outer unsealed area 12 extends beyond the end of the inner polymer layer 1203 of the first encapsulation film 121 to form a metal layer exposed area 1204. The dimension L2 of the electrode tab 2 is 35 μm; along the extension direction of the tab 2, the dimension L1 of the metal layer 1202 of the second encapsulation film 122 in the unsealed area 12 extending beyond the outer protective layer 1201 of the second encapsulation film 122 is 85 μm; along the extension direction of the tab 2, the dimension L2 of the metal layer exposed area 1204 formed by the end of the metal layer 1202 of the second encapsulation film 122 extending beyond the end of the inner polymer layer 1203 of the second encapsulation film 122 is 32 μm. After cutting, the battery width and thickness remain unchanged, the height is reduced to 88.9 mm, and the battery volumetric energy density is increased to 722.64 Wh / L. Compared with before cutting, the battery volumetric energy density is increased by 0.56% after cutting.

[0080] 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.

[0081] 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 includes a cell body and a package body (1) encapsulating the cell body, the cell body includes a tab (2); The package body (1) includes a top sealing edge (10), the tab (2) extends out of the top sealing edge (10) in a first direction; the top sealing edge (10) includes a sealing area (11) and an outer unsealed area (12) outside the sealing area (11) in the direction of the tab (2); The package body (1) includes oppositely arranged first and second encapsulation films (121) and (122), 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 end of the metal layer (1202) of the first encapsulation film (121) in the outer unsealed area (12) respectively exceeds the end of the outer protective layer (1201) and the end of the inner polymer layer (1203) of the first encapsulation film (121) to form a metal layer exposed area (1204); And / or, in the direction of the tab (2), the end of the metal layer (1202) of the second encapsulation film (122) in the outer unsealed area (12) respectively exceeds the end of the outer protective layer (1201) and the end of the inner polymer layer (1203) of the second encapsulation film (122) to form the metal layer exposed area (1204).

2. The battery of claim 1, wherein, The length of the outer unsealed area (12) satisfies: 0.2mm≤L≤0.5mm, where L is the length of the outer unsealed area (12) in the direction of the tab (2).

3. The battery of claim 2, wherein, The length of the outer unsealed area (12) and the thickness of the first or second encapsulation film (121) or (122) in a second direction satisfy: 2T<L<6T, where L is the length of the outer unsealed area (12) in the direction of the tab (2), and T is the thickness of the first or second encapsulation film (121) or (122) in the second direction; And / or, the thickness of the first or second encapsulation film (121) or (122) in the second direction satisfies: 70um≤T≤160um, where T is the thickness of the first or second encapsulation film (121) or (122) in the second direction.

4. The battery of claim 3, wherein, The metal layer exposed area (1204) includes first and second metal layer exposed areas (1204-1) and (1204-2) oppositely arranged on both sides of the metal layer (1202), respectively, the first metal layer exposed area (1204-1) is arranged on the side of the metal layer (1202) attached to the outer protective layer (1201); the second metal layer exposed area (1204-2) is arranged on the side of the metal layer (1202) attached to the inner polymer layer (1203); The length of the first metal layer exposed area (1204-1) satisfies: 50um≤L1≤150um, wherein L1 is the length of the first metal layer exposed area (1204-1); And / or, The length of the second metal layer exposed area (1204-2) satisfies: L2 5. The battery of claim 4, wherein, The sealing area (11) comprises a first part (110) near the end of the outer unsealed area (12) along the extension direction of the tab (2); The first encapsulation film (121) and the second encapsulation film (122) are respectively bonded to the first part (110); the first encapsulation film (121) and the second encapsulation film (122) of the outer unsealed area (12) each comprise an unsealed section (1205), one end of the unsealed section (1205) being connected to the first part (110) along the extension direction of the first encapsulation film (121) or the second encapsulation film (122); The extension length of the unsealed section (1205) and the one-side thickness of the first part (110) along the second direction satisfy: L3 / H1<0.8, wherein L3 is the extension length of the unsealed section (1205) along the extension direction of the first encapsulation film (121) or the second encapsulation film (122), and H1 is the one-side thickness of the first part (110) along the second direction.

6. The battery of claim 5, wherein, The first encapsulation film (121) and the second encapsulation film (122) at the end of the top sealing edge (10) extend away from the tab (2) along the second direction; the included angle formed between the first encapsulation film (121) and the second encapsulation film (122) at the end of the top sealing edge (10) satisfies: 30°≤θ≤50°, wherein θ is the included angle formed between the first encapsulation film (121) and the second encapsulation film (122) at the end of the top sealing edge (10).

7. The battery of claim 6, wherein, The tab (2) is partially coated with a tab adhesive (3) that is not bonded to the outer unsealed area (12); the projection length of the unsealed section (1205) on the tab adhesive (3) and the length of the tab adhesive (3) along the extension direction of the tab (2) satisfy: L4>L5, wherein L4 is the projection length of the unsealed section (1205) on the tab adhesive (3), and L5 is the length of the tab adhesive (3) along the extension direction of the tab (2).

8. The battery of claim 7, wherein, The metal layer exposed area (1204) on one side of the inner polymer layer (1203) forms a bare projection area (31) on the tab adhesive (3); the tab adhesive (3) is provided with a non-contact area (32) that does not contact the inner polymer layer (1203); the bare projection area (31) is completely located in the non-contact area (32).

9. The battery of claim 8, wherein, The length of the exposed projection area (31) and the thickness of the tab rubber (3) in the non-contact area (32) satisfy: L6 < T1, wherein L6 is the length of the exposed projection area (31), and T1 is the thickness of the tab rubber (3) in the non-contact area (32).

10. The battery of claim 8, wherein, The metal layer exposed area (1204) is formed with a burr (1204-3); The height of the burr (1204-3) along the third direction: M1 < 20um, wherein M1 is the height of the burr (1204-3) along the third direction; The height of the burr (1204-3) along the extension direction of the tab (2): M2 < 50um, wherein M2 is the height of the burr (1204-3) along the extension direction of the tab (2).

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