Packaging film and battery

Abstract

The utility model discloses a packaging film and a battery. The packaging film is composed of a first organic matter film layer and a second organic matter film layer, the first organic film layer comprises a wear-resistant layer; the second organic matter film layer comprises a hot melting layer; the first organic matter film layer and / or the second organic matter film layer comprise / comprises a non-metal waterproof layer. The packaging film is composed of a first organic matter film layer and a second organic matter film layer, the structural composition of the first organic matter film layer and the second organic matter film layer is optimized, and at least one of the first organic matter film layer and the second organic matter film layer is provided with a waterproof non-metal layer, so that the packaging film has an enough waterproof effect; the packaging film omits a middle metal layer with relatively high density, so that the ultrathin arrangement of the packaging film is realized, and the overall energy density of the battery is effectively improved; and due to the lack of the middle metal layer, the defect of heat conduction is avoided, the loss and waste of heat sealing energy are avoided, and the risk that the battery packaging film is corroded is avoided.

Description

Technical Field

[0001] This application relates to the technical field of rechargeable batteries, and more specifically, to a packaging film, and also to a battery including the above packaging film. Background Art

[0002] Traditional battery soft packaging films usually use aluminum-plastic packaging films. The aluminum-plastic packaging film mainly consists of three layers: an inner polypropylene film layer (CPP layer) / an intermediate aluminum foil layer (Al) / an outer nylon film layer (Nylon layer), which jointly ensure the long-term sealing performance of the battery. Among them, the functions of the three main materials of the aluminum-plastic film are as follows: CPP layer: resistant to electrolyte corrosion, avoiding contact between the Al layer and the electrolyte, and having a melting sealing function; Al layer: preventing water vapor from penetrating into the core of the battery; Nylon layer has a certain puncture resistance and a protective function.

[0003] Among them, due to the heat conduction of the Al layer, the heat sealing temperature of the traditional aluminum-plastic packaging film is higher than the melting temperature of the inner layer, resulting in losses of process energy and higher requirements for the encapsulation of the battery packaging film; in addition, the presence of the Al layer not only makes the soft-packaged battery using the aluminum-plastic film always have a risk of corrosion, but also the presence of the Al layer also reduces the overall energy density of the battery to a certain extent. Summary of the Utility Model

[0004] In view of this, this application provides a packaging film, and also provides a battery including the above packaging film, which solves the problems of excessive heat sealing temperature of traditional aluminum-plastic packaging films, corrosion risks of batteries, and low energy density of batteries.

[0005] In order to achieve the above object, this application provides the following technical solutions:

[0006] A packaging film, which consists of a first organic film layer and a second organic film layer;

[0007] The first organic film layer includes an abrasion-resistant layer;

[0008] The second organic film layer includes a heat-melt layer;

[0009] The first organic film layer and / or the second organic film layer includes a non-metallic waterproof layer.

[0010] Optionally, in the above packaging film,

[0011] The abrasion-resistant layer includes any one of nylon, polychlorotrifluoroethylene, polyethylene terephthalate, saturated polyester, and fluorinated ethylene propylene copolymer; and / or,

[0012] At least one surface of the abrasion-resistant layer is provided with a polymer coating, and the polymer coating forms the non-metallic waterproof layer.

[0013] Optionally, in the above packaging film,

[0014] the polymer coating is a parylene coating; and / or,

[0015] the thickness of the polymer coating is H2, where 10 nm ≤ H2 ≤ 1000 nm.

[0016] Optionally, in the above packaging film, the second organic film layer is composed of a first layer, a non-metallic waterproof layer, and a second layer stacked in sequence;

[0017] both the first layer and the second layer are the heat-melt layers;

[0018] the non-metallic waterproof layer includes a water-swellable functional polymer.

[0019] Optionally, in the above packaging film,

[0020] both the first layer and the second layer are polyacrylic acid-styrene copolymers; and / or,

[0021] the thickness of the second organic film layer is H3, where 20 μm ≤ H3 ≤ 50 μm; and / or,

[0022] the heat-melt temperature of the second organic film layer is T3, where 165 °C ≤ T3 ≤ 170 °C.

[0023] Optionally, in the above packaging film,

[0024] the thickness of the wear-resistant layer is H1, where 10 μm ≤ H1 ≤ 30 μm; and / or,

[0025] the melting temperature of the wear-resistant layer is T1, where 170 °C ≤ T1 ≤ 300 °C.

[0026] Optionally, in the above packaging film,

[0027] the water vapor transmission rate of the packaging film is ≤ 0.2 g / (m2·d); and / or,

[0028] the thickness of the packaging film is ≤ 50 μm.

[0029] Optionally, in the above packaging film, an adhesive is provided between the first organic film layer and the second organic film layer; the thickness of the adhesive is H4, where 1 μm ≤ H4 ≤ 9 μm.

[0030] A battery includes an electric core and a packaging film for encapsulating the electric core, and the packaging film is the packaging film described above; the heat-sealing temperature of the packaging film is T, the heat-sealing thickness is H, the heat-sealing air pressure is P, and the heat-sealing time is t, where:

[0031] T3 + T3×(H1 + H3) / (0.68P×1.12t) ≤ T ≤ T1; and / or,

[0032] H1×(1 - 0.02P) + H3×(1 - 0.3P*T) + H2 + H4 ≤ H ≤ H1 + H2 + H3 + H4; and / or,

[0033] T3 ≤ T ≤ T1; and / or,

[0034] H ≤ 50μm.

[0035] Optionally, in the above battery, the packaging film includes a top seal portion and a side seal portion; the battery cell includes a tab extending out of the top seal portion, and along the thickness direction of the battery cell, tab adhesives are bonded to both surfaces of the tab, and the tab adhesives are heat-sealed to the top seal portion, where:

[0036] Along the center of the battery cell to the edge of the battery cell, the width of the top seal portion is W1, 1.5 mm ≤ W1 ≤ 4 mm; and / or,

[0037] Along the center of the battery cell to the edge of the battery cell, the width of the side seal portion is W2, 1.5 mm ≤ W2 ≤ 4 mm; and / or,

[0038] The top seal heat-sealing strength of the top seal portion is S1, S1 ≥ 35 N / 15 m; and / or,

[0039] The side seal heat-sealing strength of the side seal portion is S2, S2 ≥ 35 N / 15 m; and / or,

[0040] Along the extending direction of the top seal portion, the width of the tab is W3, 2.5 mm ≤ W3 ≤ 3.5 mm; and / or,

[0041] Along the thickness direction of the battery cell, the thickness of the tab is D1, 0.05 mm ≤ D1 ≤ 0.1 mm; and / or,

[0042] Along the extending direction of the top seal portion, the width of the tab adhesive is W4, 3.5 mm ≤ W4 ≤ 4.5 mm; and / or,

[0043] Along the extending direction of the tab, the length of the tab adhesive is L, 2 mm ≤ L ≤ 5 mm; and / or,

[0044] Along the thickness direction of the battery cell, the thickness of the tab adhesive is D2, 0.045 mm ≤ D2 ≤ 0.065 mm.

[0045] In the packaging film and battery provided by the present application, the packaging film is composed of a first organic film layer and a second organic film layer, and the structural compositions of the first organic film layer and the second organic film layer are optimized so that at least one of them is provided with a waterproof non-metal layer to make it have sufficient waterproof effect; the packaging film omits the intermediate metal layer with a relatively large density, so the ultra-thin setting of the packaging film is realized, effectively improving the overall energy density of the battery; moreover, due to the absence of the intermediate metal layer, the disadvantage of heat conduction no longer exists, avoiding the loss and waste of heat-sealing energy, and the battery packaging film no longer has the risk of being corroded. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] 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 required to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0047] Figure 1 It is a schematic structural diagram of the packaging film of the present application;

[0048] Figure 2 It is a schematic structural diagram of the packaging film of the present application;

[0049] Figure 3 It is a schematic diagram of the packaging film of the present application before top sealing;

[0050] Figure 4 It is a schematic diagram of the packaging film of the present application after top sealing;

[0051] Figure 5 It is a schematic diagram of the packaging film of the present application before side sealing;

[0052] Figure 6 It is a schematic diagram of the packaging film of the present application after side sealing.

[0053] Figures 1 - 6 Wherein:

[0054] 1. First organic film layer; 2. Second organic film layer; 3. Adhesive; 4. Packaging film; 5. Tab; 6. Tab glue;

[0055] 11. Wear-resistant layer; 12. Polymer coating;

[0056] 21. First layer; 22. Intermediate layer; 23. Second layer;

[0057] 41. Top sealing part; 42. Side sealing part. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0058] The present application provides a packaging film and also provides a battery including the above-mentioned packaging film.

[0059] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a 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 of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0060] As Figures 1 - 6 shown, a packaging film is composed of a total of two functional film layers, namely a first organic film layer 1 and a second organic film layer 2. The first organic film layer 1 includes an abrasion-resistant layer 11. The second organic film layer 2 includes a heat-melt layer. The first organic film layer 1 and / or the second organic film layer 2 includes a non-metallic waterproof layer.

[0061] It should be noted that the packaging film is composed of two functional film layers, where the first organic film layer 1 is located on the outside and the second organic film layer 2 is located on the inside. The packaging film is used as the outer packaging film of the battery cell to hermetically wrap the battery cell. The wrapping process is as follows: Cut out a packaging film of an appropriate size according to the size of the battery cell. The packaging film includes a first packaging film and a second packaging film that can be folded in half, and ensure that both are sufficient to completely wrap the battery cell and leave enough edges for heat sealing; Place the battery cell inside the cut first packaging film, and then fold the second packaging film to the first packaging film to wrap the battery cell, and ensure that the positive and negative electrode tabs of the battery cell extend outside the packaging film; Use a heat-sealing device to perform top sealing and side sealing on the first packaging film and the second packaging film to completely seal the battery cell in the packaging film.

[0062] It should be further noted that a non-metallic waterproof layer stacked with the abrasion-resistant layer 11 can be provided only in the first organic film layer 1; a non-metallic waterproof layer stacked with the heat-melt layer can be provided only in the second organic film layer 2; Of course, a non-metallic waterproof layer stacked with the abrasion-resistant layer 11 can be provided in the first organic film layer 1, and a non-metallic waterproof layer stacked with the heat-melt layer can also be provided in the second organic film layer 2.

[0063] The packaging film is only composed of two organic films, namely the first organic film layer 1 and the second organic film layer 2. The structural compositions of the first organic film layer 1 and the second organic film layer 2 are optimized, and at least one of them is provided with a waterproof non-metal layer to achieve sufficient waterproof effect; the whole packaging film is composed of organic substances, eliminating the intermediate metal layer with a relatively large density, thus realizing the ultra-thin setting of the packaging film and effectively improving the overall energy density of the battery; moreover, due to the absence of the intermediate metal layer, the disadvantage of heat conduction no longer exists, avoiding the loss and waste of heat-sealing energy. The top-sealing / side-sealing requirements of the packaging film are low, resulting in high heat-sealing strength and good effect; furthermore, there are no metal elements in the packaging film, avoiding the risk of battery corrosion.

[0064] In some embodiments of the present application, the wear-resistant layer 11 includes one or more of nylon, polychlorotrifluoroethylene, polyethylene terephthalate, saturated polyester, and fluorinated ethylene propylene copolymer. Preferably, the wear-resistant layer 11 is polychlorotrifluoroethylene and polyethylene terephthalate.

[0065] The wear-resistant layer 11 of the above components enhances the friction and abrasion resistance of the outer surface of the packaging film, and can effectively prevent the film material damage of the packaging film caused by friction and scratching during production and use, thereby protecting the internal battery core from external influences.

[0066] In some embodiments, a polymer coating layer 12 is provided on at least one surface of the wear-resistant layer 11, and the polymer coating layer 12 forms a non-metal waterproof layer.

[0067] On one side surface or both side surfaces of the wear-resistant layer 11, one or two dense polymer coating layers 12 are obtained by vacuum evaporation plating; the polymer coating layer 12 has the advantages of precisely controllable coating thickness, dense and uniform coating, and strong surface adhesion. As the non-metal waterproof layer formed on the first organic film layer 1, the polymer coating layer 12 increases the waterproof performance of the first organic film layer 1, and thus can replace the metal layer provided in the packaging film, realizing the overall organic composition of the packaging film.

[0068] In some embodiments of the present application, the polymer coating layer 12 is a parylene coating.

[0069] Furthermore, the polymer coating layer 12 is one or more of various types of parylene coatings such as N-type, C-type, D-type, F-type, and HT-type. As above, the type of the polymer coating layer 12 can be flexibly set according to actual needs, with strong flexibility and applicability. The parylene coating is very thin and uniform, almost free of any pinholes, providing excellent moisture and dust protection for the first organic film layer 1; at the same time, its thickness can range from the nanometer level to dozens of micrometers, suitable for occasions with strict requirements for weight and space, ensuring that the thickness and weight of the first organic film layer 1 will not increase too much, and thus effectively ensuring the energy density of the battery.

[0070] In some embodiments of the present application, the thickness of the polymer coating 12 is H2, where 10 nm ≤ H2 ≤ 1000 nm. For example, H2 can be any one of 10 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm. Preferably, H2 is 500 nm.

[0071] As described above, the thickness of the polymer coating 12 has been thinned. On the premise of ensuring its excellent waterproof performance, it is ensured that the thickness dimension of the finally formed first organic film layer 1 will not increase too much, thereby effectively ensuring the energy density of the battery.

[0072] In some embodiments of the present application, the second organic film layer 2 is composed of a first layer 21, a non-metallic waterproof layer, and a second layer 23 stacked in sequence. The first layer 21 and the second layer 23 are hot-melt layers; the non-metallic waterproof layer includes a water-swellable functional polymer.

[0073] In some embodiments, both the first layer 21 and the second layer 23 are poly(acrylic acid-styrene) copolymers.

[0074] It should be noted that the second organic film layer 2 is a polypropylene film layer; the polypropylene film layer is produced by a three-layer co-extrusion process to obtain the stacked first layer 21, intermediate layer 22, and second layer 23; the first layer 21 and the second layer 23 are copolymers formed by the polymerization of acrylic acid and styrene, namely poly(acrylic acid-styrene) copolymers, which serve as the hot-melt layers of the second organic film layer 2; the intermediate layer 22 is polyacrylic acid doped with a water-swellable functional polymer, forming a non-metallic waterproof layer, which increases the water absorption performance of the second organic film layer 2, so that the water passing through the first organic film layer 1 can be adsorbed by the non-metallic waterproof layer, thereby preventing water from passing through the second organic film layer 2 and entering the inside of the packaging film to affect the battery core, enabling the second organic film layer 2 to absorb and fix water, and thus achieving good waterproof performance. Therefore, the metal layer provided in the packaging film can be cancelled, realizing the overall organic composition of the packaging film.

[0075] Furthermore, the water-swellable functional polymer is insoluble in water and hardly soluble in organic solvents; the molecular chain of the water-swellable functional polymer contains one or more hydrophilic groups -OH, -COOH, -CONH2, -SO3H.

[0076] Preferably, the water-swellable functional polymer is one or more of polyvinyl alcohol polymers, polyacrylate polymers, and acrylamide-acrylate copolymer crosslinks. As described above, the non-metal waterproof layer can be ensured to have excellent water absorption and water retention properties, thereby achieving a waterproof effect, ensuring the waterproof seal of the packaging film, and realizing the waterproof protection of the internal battery cell.

[0077] Please refer to the appendix Figure 1 , in some embodiments, only the middle layer 22 of the second organic film layer 2 is doped with a water-swellable functional polymer, and the middle layer 22 is a non-metal water-absorbing layer, thereby forming a protective non-metal waterproof layer; and no polymer coating is vapor-deposited on the surface of the wear-resistant layer 11 of the first organic film layer 1, and it no longer has waterproof performance.

[0078] Please refer to the appendix Figure 2 , in some embodiments, only a polymer coating 12 is vapor-deposited on the surface of the wear-resistant layer 11 of the first organic film layer 1 to form a protective non-metal waterproof layer; and the first layer 21 and the second layer 23 of the second organic film layer 2 are copolymers formed by polymerizing polyacrylic acid and styrene, and the middle layer 22 of the second organic film layer 2 is a homopolymer of polyacrylic acid, and the middle layer 22 is a non-waterproof layer.

[0079] Please refer to the appendix Figure 2 , in some embodiments, a polymer coating 12 is vapor-deposited on the surface of the wear-resistant layer 11 of the first organic film layer 1 to form a first protective non-metal waterproof layer, and a water-absorbing polymer is doped in the middle layer 22 of the second organic film layer 2 to form a second protective non-metal waterproof layer; as described above, the effect of blocking water vapor permeation of the first organic film layer 1 and the water retention effect of the second organic film layer 2 are achieved, and the water vapor permeation rate of the packaging film is reduced under the dual strategy.

[0080] In some embodiments of the present application, the thickness of the second organic film layer 2 is H3, 20 μm ≤ H3 ≤ 50 μm. For example, H3 can be any one of 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, and 50 μm. Preferably, H3 is 30 μm.

[0081] As described above, on the premise of ensuring the heat-sealing performance and water absorption and water retention performance of the second organic film layer 2, the thickness dimension of the second organic film layer 2 is ensured not to be too large, and the energy density of the battery is ensured.

[0082] In some embodiments, the hot-melt temperature of the second organic film layer 2 is T3, 165 °C ≤ T3 ≤ 170 °C. For example, T3 can be any one of 165 °C, 166 °C, 167 °C, 168 °C, 169 °C, and 170 °C.

[0083] When the packaging film is heat-sealed, the heat-sealing temperature will be slightly higher than the melting temperature of the second organic film layer 2. Limiting the melting temperature of the second organic film layer 2 within the above range can just cause sufficient chemical and physical reactions between the second organic film layer 2 and the electrode surface material to form a stable sealing interface.

[0084] In some embodiments of the present application, the weight percentage of the water-swellable functional polymer in the second organic film layer 2 is A, 5wt% ≤ A ≤ 10wt%. For example, A can be any one of 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%. Preferably, A is 9wt%.

[0085] As above, on the premise of ensuring that the intermediate layer 22 of the second organic film layer 2 has sufficient water absorption and water retention performance, ensure that the thickness dimension of the second organic film layer 2 is not too large to ensure the energy density of the battery.

[0086] In some embodiments of the present application, the thickness of the wear-resistant layer 11 is H1, 10μm ≤ H1 ≤ 30μm. For example, H1 can be any one of 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, 30μm. Preferably, H1 is 12μm.

[0087] As above, on the premise of ensuring that the wear-resistant layer 11 has sufficient anti-friction performance, avoid its thickness dimension being too large and affecting the energy density of the battery.

[0088] In some embodiments, the melting temperature of the wear-resistant layer 11 is T1, 170°C ≤ T1 ≤ 300°C. For example, T1 can be any one of 170°C, 200°C, 230°C, 250°C, 260°C, 280°C, 300°C. Preferably, 200°C ≤ T1 ≤ 260°C.

[0089] As above, ensure that the wear-resistant layer 11 has a relatively high melting temperature, which is higher than the heat-sealing temperature of the aluminum-plastic film, avoid melting the wear-resistant layer 11 during heat-sealing, ensure that the wear-resistant layer 11 is not damaged, and ensure its mechanical strength, wear resistance, and tear resistance.

[0090] In some embodiments of the present application, the water vapor transmission rate of the packaging film ≤ 0.2g / (m2·d).

[0091] Furthermore, the thickness of the packaging film ≤ 50μm.

[0092] By evaporating and depositing a polymer coating layer 12 on the surface of the wear-resistant layer 11 of the first organic film layer 1, the effect of the first organic film layer 1 blocking the permeation of water vapor is achieved, forming a first non-metal waterproof layer for the first protection; by doping a water-absorbing polymer in the intermediate layer 22 of the second organic film layer 2, the water absorption and water fixation effects of the second organic film layer 2 are achieved, forming a second non-metal waterproof layer for the second protection. Under the dual strategy, the water vapor transmission rate of the packaging film can be maintained within a lower range, improving the waterproof performance of the packaging film.

[0093] Furthermore, due to the setting of the non-metal waterproof layer, the metal layer provided in the packaging film is removed, realizing the overall organic composition of the packaging film, which is soft in texture and can maintain the thickness of the first organic film layer 1 within a smaller size range, ensuring the energy density of the battery.

[0094] In some embodiments of the present application, an adhesive 3 is provided between the first organic film layer 1 and the second organic film layer 2; the thickness of the adhesive 3 is H4, and 1μm ≤ H4 ≤ 9μm. For example, H4 can be any one of 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm. Preferably, H4 is 3μm.

[0095] It should be noted that the adhesive 3 includes one or more of acrylate adhesives, polyurethane adhesives, vinyl alcohol adhesives, and polyolefin adhesives.

[0096] Through the adhesive 3, the reliable bonding and fixing effect between the first organic film layer 1 and the second organic film layer 2 is achieved, avoiding the occurrence of fault cracking during use and ensuring the consistency of the packaging film structure.

[0097] Limiting the thickness of the adhesive 3 within the above range can ensure that the thickness dimension of the adhesive 3 is not too large on the premise of ensuring the reliable bonding between the first organic film layer 1 and the second organic film layer 2, ensuring the energy density of the battery.

[0098] In summary, the present application also provides a battery, which includes a battery cell and a packaging film 4 for encapsulating the battery cell, and the packaging film 4 is the packaging film described above.

[0099] It should be noted that the battery cell is a wound cell or a stacked cell. The battery cell includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet. The packaging film 4 is top-sealed and side-sealed through a high-temperature hot pressing process to hermetically package the battery cell.

[0100] It should be further noted that the battery is a rechargeable battery, preferably a lithium-ion battery; in addition to lithium-ion batteries, it can also be a sodium-ion battery, a potassium-ion battery, a semi-solid battery, a solid-state battery, etc. When the battery is a non-solid-state battery, an electrolyte needs to be filled in the packaging film 4, and the electrolyte and the battery cell are both hermetically packaged in the packaging film 4.

[0101] Since the battery of the present application has the packaging film 4 described above, for the beneficial effects brought by the packaging film 4 to the battery, please refer to the above, and will not be elaborated here.

[0102] In some embodiments of the present application, the heat-sealing temperature of the packaging film 4 is T (unit: °C), the heat-sealing thickness of the packaging film 4 is H (unit: μm), the heat-sealing air pressure is P (unit: MPa), and the heat-sealing time is t (unit: s). The heat-sealing temperature T of the packaging film 4 is mainly related to the heat-sealing air pressure P and the heat-sealing time t, and satisfies the following formula:

[0103] T3 + T3×(H1 + H3) / (0.68P×1.12t) ≤ T ≤ T1.

[0104] Further, T3 ≤ T ≤ T1.

[0105] The upper limit value of the heat-sealing temperature T of the packaging film 4 is less than the melting temperature T1 of the wear-resistant layer 11, and the lower limit value of the heat-sealing temperature T is greater than the melting temperature T3 of the second organic film layer 2; more precisely, the lower limit value of the heat-sealing temperature T is jointly determined by the melting temperature T3 of the second organic film layer 2, the thickness H1 of the wear-resistant layer 11, the thickness H3 of the second organic film layer 2, the heat-sealing air pressure P, and the heat-sealing time t. Therefore, according to the changes of the above parameters, the actual heat-sealing temperature T of the packaging film 4 can be reasonably adjusted to meet the heat-sealing requirements and ensure the heat-sealing effect.

[0106] In some embodiments, the heat-sealing thickness H of the packaging film 4 is mainly related to the heat-sealing air pressure P and the heat-sealing temperature T, and satisfies the following formula:

[0107] H1×(1 - 0.02P) + H3×(1 - 0.3P*T) + H2 + H4 ≤ H ≤ H1 + H2 + H3 + H4.

[0108] Further, H ≤ 50 μm.

[0109] It should be noted that the heat-sealing thickness H of the packaging film 4 is calculated as the thickness of the single-layer packaging film 4 after heat-sealing, that is, half of the thickness of the double-layer packaging film folded after heat-sealing.

[0110] The upper limit value of the heat-sealing thickness H of the packaging film 4 is less than the sum of the thickness H1 of the wear-resistant layer 11, the thickness H2 of the polymer coating layer 12, the thickness H3 of the second organic film layer 2, and the thickness H4 of the adhesive 3; the lower limit value of the heat-sealing thickness H is jointly determined by the thickness H1 of the wear-resistant layer 11, the thickness H3 of the organic film layer 2, the heat-sealing air pressure P, and the heat-sealing temperature T. Therefore, according to the energy density that the battery needs to meet, by adjusting the above parameters, the packaging film 4 can have an appropriate heat-sealing thickness to meet the requirements of battery performance.

[0111] In some embodiments of the present application, the packaging film 4 includes a top seal portion 41 and a side seal portion 42. The battery cell includes tabs 5 extending out of the top seal portion 41. Along the thickness direction of the battery cell, tab adhesives 6 are bonded to both side surfaces of the tab 5, and the tab adhesives 6 are heat-sealed to the top seal portion 41.

[0112] It should be noted that the thickness direction of the battery cell is the direction indicated by the arrow in the attachment. The top seal portion 41 of the packaging film 4 is obtained by top-sealing through a high-temperature hot-pressing process, and the side seal portion 42 of the packaging film 4 is obtained by side-sealing through a high-temperature hot-pressing process. The top seal portion 41 and the side seal portion 42 within a unit sample are subjected to a peel strength test to obtain the encapsulation strength. Figure 4 Please refer to the attachment, which is a schematic structural diagram of the heat-sealing of the top seal portion 41. Along the center of the battery cell to the edge of the battery cell, the width of the top seal portion 41 is W1, and 1.5 mm ≤ W1 ≤ 4 mm. For example, W1 can be any one of 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, and 4 mm.

[0113] Please refer to the attachment Figures 3 - 4 which is a schematic structural diagram of the heat-sealing of the top seal portion 41. Along the center of the battery cell to the edge of the battery cell, the width of the top seal portion 41 is W1, and 1.5 mm ≤ W1 ≤ 4 mm. For example, W1 can be any one of 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, and 4 mm.

[0114] It should be noted that on the side where the top seal portion 41 is located, along the direction from the center of the battery cell to the edge of the battery cell, that is, the direction perpendicular to the plane of the attachment Figure 4 where it is located.

[0115] Please refer to the attachment Figures 5 - 6 which shows that further, along the center of the battery cell to the edge of the battery cell, the width of the side seal portion 42 is W2, and 1.5 mm ≤ W2 ≤ 4 mm. For example, W2 can be any one of 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, and 4 mm.

[0116] It should be noted that on the side where the side seal portion 42 is located, along the direction from the center of the battery cell to the edge of the battery cell, that is, the direction perpendicular to the plane of the attachment Figure 6 where it is located.

[0117] Furthermore, the top-sealing heat-sealing strength of the top seal portion 41 is S1, and S1 ≥ 35 N / 15 m.

[0118] Furthermore, the side-sealing heat-sealing strength of the side seal portion 42 is S2, and S2 ≥ 35 N / 15 m.

[0119] As described above, it is ensured that both the top seal portion 41 and the side seal portion 42 have sufficient heat-sealing width dimensions, and further, it is ensured that both the top seal portion 41 and the side seal portion 42 have sufficient heat-sealing strength, ensuring that during the charging and discharging process of the battery and under conditions such as transportation and storage, the packaging film can effectively protect the internal structure of the battery, prevent electrolyte leakage, moisture and oxygen penetration, and ensure the performance and safety of the battery.

[0120] Please refer to the attachment Figure 4, in some embodiments, along the extending direction of the top sealing part 41, the width of the tab 5 is W3, where 3.5 mm ≤ W3 ≤ 4 mm. For example, W3 can be any one of 2.5 mm, 2.7 mm, 3 mm, 3.3 mm, and 3.5 mm.

[0121] It should be noted that the extending direction of the top sealing part 41 is the direction indicated by the arrow in the Figure 4 drawing.

[0122] Furthermore, along the thickness direction of the battery cell, the thickness of the tab 5 is D1, where 0.05 mm ≤ D1 ≤ 0.1 mm. For example, D1 can be any one of 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, and 0.1 mm.

[0123] As described above, limiting the size of the tab 5 within the above range can ensure the current-carrying capacity of the tab 5 to meet the usage performance of the battery.

[0124] Please refer to the Figure 4 drawing. In some embodiments, along the extending direction of the top sealing part 41, the width of the tab glue 6 is W4, where 3.5 mm ≤ W4 ≤ 4.5 mm. For example, W4 can be any one of 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm, and 4 mm.

[0125] It should be noted that the tab glue 6 is modified polypropylene.

[0126] Limiting the width of the tab glue 6 within the above range can ensure that the width W4 of the tab glue 6 is greater than the width W3 of the tab 5, so as to achieve the full coverage effect of the tab glue 6 on the tab 5 in the width direction, and further ensure the tight sealing effect of the tab 5 on the top sealing part 41.

[0127] Furthermore, along the extending direction of the tab 5, the length of the tab glue 6 is L, where 2 mm ≤ L ≤ 5 mm. For example, L can be any one of 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, and 5 mm.

[0128] It should be noted that please refer to the Figure 4 drawing. The extending direction of the tab 5 is perpendicular to the thickness direction of the battery cell and the extending direction of the top sealing part 41 respectively.

[0129] Limiting the length of the tab glue 6 within the above range can ensure that the length L of the tab glue 6 is greater than the width W1 of the top sealing part 41, and further ensure the full sealing effect of the tab glue 6 within the top sealing part 41.

[0130] Further, in the thickness direction of the battery cell, the thickness of the tab glue 6 is D2, where 0.045 mm ≤ D2 ≤ 0.065 mm. For example, D2 can be any one of 0.045 mm, 0.050 mm, 0.055 mm, 0.060 mm, and 0.065 mm.

[0131] By limiting the thickness of the tab glue 6 within the above range, on the premise of ensuring a firm bonding effect between the tab glue 6 and the tab 5 at the top sealing part 41, the thickness dimension of the tab glue 6 is prevented from being too large, ensuring the energy density of the battery.

[0132] Preferably, the width W1 of the top sealing part 41 is 4 mm.

[0133] Preferably, the width W3 of the tab 5 is 3 mm, and the thickness of the tab 5 is 0.8 mm.

[0134] Preferably, the width W4 of the tab glue 6 is 4 mm, the length L is 1.5 mm, and the thickness D2 of a single tab glue 6 is 0.055 mm.

[0135] As described above, the tab glue 6 can not only be firmly connected to the tab 5, but also form a wide heat-sealing area on the surface in contact with the top sealing part 41, enhancing the sealing effect of the package and preventing the leakage of the electrolyte and the entry of external impurities into the battery interior.

[0136] It should be noted that the preparation process of the packaging film 4 is as follows:

[0137] 1. Prepare the first organic film layer 1 with different thicknesses and materials through a compression molding process, an injection molding process, or a coextrusion molding process; prepare the second organic film layer 2 through a three-layer coextrusion molding process;

[0138] 2. The surfaces of the first organic film layer 1 that need to contact the adhesive 3 and the surfaces of the second organic film layer 2 that need to contact the adhesive 3 are subjected to a corona treatment;

[0139] 3. Coat the adhesive 3 between the corona-treated surface of the first organic film layer 1 and the corona-treated surface of the second organic film layer 2. After baking at 65 °C, the adhesive 3 firmly bonds the first organic film layer 1 and the second organic film layer 2 together.

[0140] Among them, the preparation process of the first organic film layer 1 is as follows:

[0141] ① The solid raw material (xylene polymer) evaporates and sublimes into a dimer gas at a temperature of 140 °C, and is further heated to 650 °C to crack the dimer to generate stable active monomers;

[0142] ② Keep the container equipped with the wear-resistant layer 11 under reduced pressure to create a vacuum, thereby sucking out the gaseous active monomers in step ① and feeding them into the deposition chamber;

[0143] ③ The active monomers enter the deposition chamber and undergo polymerization deposition at room temperature, instantaneously adsorbing on the surface of the wear-resistant layer 11 and polymerizing into a parylene coating (poly-p-xylene film).

[0144] Among them, the preparation process of the second organic film layer 2 is as follows:

[0145] ① The second organic film layer 2 is a three-layer co-extruded polyacrylic acid (CPP) film, and its three-layer structure is respectively named the first layer 21, the middle layer 22, and the second layer 23; the mass percentage is the first layer 21: the middle layer 22: the second layer 23 = 1:3:1; the slurries of the first layer 21 and the second layer 23 are both copolymers formed by polymerizing polyacrylic acid and styrene; the middle layer 22 can be a non-water-absorbing layer or a non-metal water-absorbing layer;

[0146] ② The slurry of the non-water-absorbing layer is a polyacrylic acid homopolymer;

[0147] ③ Preparation method of the slurry of the non-metal water-absorbing layer: Granulate the water-absorbing polymer: CPP = 1:1, and then melt the granulated particles: CPP = 3:7.

[0148] Battery preparation:

[0149] Prepare a conventional lithium cobalt oxide soft-pack battery using the packaging film 4 of the embodiment;

[0150] 1. Stir the positive electrode active material, conductive agent, binder, and solvent evenly and mix them, then coat them on the surface of the positive electrode substrate to obtain a positive electrode sheet; among them, the specification of the positive electrode substrate is 8μm aluminum foil; dry and roll the prepared electrode sheet to obtain a positive electrode sheet; Stir the negative electrode active material graphite, conductive agent, binder, and solvent evenly and mix them, then coat them on the surface of the negative electrode substrate to obtain a negative electrode sheet; among them, the specification of the negative electrode substrate is 6μm copper foil; dry and roll the prepared electrode sheet to obtain a negative electrode sheet;

[0151] 2. Weld the positive electrode tab at the empty foil of the aluminum foil and the negative electrode tab at the empty foil of the copper foil, and wind them together with the separator to obtain a wound core; among them, the specifications of the positive / negative electrode tabs are that the tab width is 3mm and the thickness is 0.08mm. The tab comes with a tab adhesive, and the tab adhesive is a modified polypropylene with a specification of a width of 4mm, a length of 4.5mm, and a single-sided adhesive thickness of 0.055mm.

[0152] 3. Place the prepared multiple wound cores into the packaging films prepared in the above embodiments and the packaging films of the comparative examples respectively, and then obtain lithium-ion batteries with a voltage of 4.45V and a capacity of 403mAh through processes such as liquid injection, sealing, aging, formation, second sealing, and OCV.

[0153] Water vapor transmission rate test:

[0154] The packaging films obtained in Examples 1-3 and the packaging films of Comparative Examples 1-2 were subjected to water vapor transmission rate test in accordance with GB / T 1037-1988 "Test Method for Water Vapor Transmission of Plastic Films and Sheets - Cup Method" (referring to WPT-301B water vapor transmission rate tester, using the weighing method of moisture permeation cup as the test principle). The specific operation steps were as follows: At 38 °C and a relative humidity of 90%, a specific humidity difference was formed on both sides of the specimen. Water vapor passed through the specimen in the moisture permeation cup into the dry side, and by measuring the change in the weight of the moisture permeation cup over time, parameters such as the water vapor transmission rate of the specimen were obtained.

[0155] Cell drop test:

[0156] The packaging films obtained in Examples 1-3 and the packaging films of Comparative Examples 1-2 were used to prepare conventional lithium cobalt oxide soft-pack batteries and subjected to a 1.2-meter drop test in accordance with SJ / T 11169-1998 "Lithium Battery Standard Drop Test" and GB 31241-2014 "Drop Test". The purpose of the 1.2-meter drop test for lithium-ion batteries was mainly to consider the impact resistance of lithium-ion batteries when subjected to external forces during transportation and carrying.

[0157] Example 1

[0158] As Figure 1 shown, in the first organic film layer 1, the wear-resistant layer 11 is a polychlorotrifluoroethylene film (PCTFE film) with a thickness of 15 μm.

[0159] The second organic film layer 2 is a three-layer co-extruded polypropylene film (CPP film). The first layer 21 and the second layer 23 are copolymers formed by the polymerization of polyacrylic acid and styrene, and the middle layer 22 is a non-metallic water-absorbing layer, which is polyacrylic acid added with 9 wt% acrylamide-acrylate copolymer cross-linking agent. The total thickness of the three layers is 30 μm.

[0160] In the packaging film 4, the PCTFE film layer and the CPP film layer are adhered and fixed with the adhesive 3. The adhesive 3 is a polyurethane-based adhesive with a thickness of 3 μm.

[0161] The initial thickness of the packaging film 4 is 48 μm, and it is subjected to heat sealing treatment at a gradient temperature of 165 °C - 180 °C, a pressure of 0.2 MPa - 0.5 MPa, and a time of 2 s - 5 s.

[0162] Example 2

[0163] As Figure 2 shown, in the first organic film layer 1, the wear-resistant layer 11 is a polychlorotrifluoroethylene film (PCTFE film) with a thickness of 15 μm. The polymer coating 12 is a dense parylene coating vacuum-evaporated on the outer surface of PCTFE with a thickness of 500 nm.

[0164] The second organic film layer 2 is a three-layer co-extruded polypropylene film (CPP film). The first layer 21 and the second layer 23 are copolymers formed by the polymerization of polyacrylic acid and styrene. The middle layer 22 is a non-water-absorbing layer, which is a homopolymer of polyacrylic acid. The total thickness of the three layers is 30 μm.

[0165] In the packaging film 4, the PCTFE film layer and the CPP film layer are adhered to each other and fixed with an adhesive 3. The adhesive 3 is a polyurethane-based adhesive with a thickness of 3 μm.

[0166] The initial thickness of the packaging film 4 is 48.5 μm, and it is subjected to heat sealing treatment at a gradient temperature of 165 °C - 180 °C, a pressure of 0.2 MPa - 0.5 MPa, and a time of 2 s - 5 s.

[0167] Example 3

[0168] As Figure 2 shown, in the first organic film layer 1, the wear-resistant layer 11 is a polychlorotrifluoroethylene film (PCTFE film) with a thickness of 15 μm. The polymer coating layer 12 is a dense parylene coating deposited by vacuum evaporation on the outer surface of PCTFE, with a thickness of 500 nm.

[0169] The second organic film layer 2 is a three-layer co-extruded polypropylene film (CPP film). The first layer 21 and the second layer 23 are copolymers formed by the polymerization of polyacrylic acid and styrene. The middle layer 22 is a non-metallic water-absorbing layer, which is polyacrylic acid added with 9 wt% acrylamide-acrylate copolymer crosslinking agent. The total thickness of the three layers is 30 μm.

[0170] In the packaging film 4, the PCTFE film layer and the CPP film layer are adhered to each other and fixed with an adhesive 3. The adhesive 3 is a polyurethane-based adhesive with a thickness of 3 μm.

[0171] The initial thickness of the packaging film 4 is 48.5 μm, and it is subjected to heat sealing treatment at a gradient temperature of 165 °C - 180 °C, a pressure of 0.2 MPa - 0.5 MPa, and a time of 2 s - 5 s.

[0172] Comparative Example 1

[0173] In the first organic film layer 1, the wear-resistant layer 11 is a polychlorotrifluoroethylene film (PCTFE film) with a thickness of 15 μm.

[0174] The second organic film layer 2 is a three-layer co-extruded polypropylene film (CPP film). The first layer 21 and the second layer 23 are copolymers formed by the polymerization of polyacrylic acid and styrene. The middle layer 22 is a non-water-absorbing layer, which is a homopolymer of polyacrylic acid. The total thickness of the three layers is 30 μm.

[0175] In the packaging film 4, the PCTFE film layer and the CPP film layer are attached to each other and fixed with the adhesive 3, and the adhesive 3 is a polyurethane-based adhesive with a thickness of 3μm.

[0176] The initial thickness of the packaging film 4 is 48μm, and it is subjected to heat sealing treatment at a gradient temperature of 165°C - 180°C, a pressure of 0.2MPa - 0.5MPa, and a time of 2s - 5s.

[0177] Comparative Example 2

[0178] The comparative example is an aluminum-plastic film with a thickness of 86μm, and its structures from the outside to the inside are: a nylon layer of 15μm, an adhesive layer of 3μm, an aluminum foil layer of 35μm, an adhesive layer of 3μm, and a polypropylene layer of 30μm.

[0179] Table 1 Detection results of water vapor transmission rate and battery drop in each example and comparative example

[0180] Group Water vapor transmission rate Battery drop Example 1 <![CDATA[0.17 g / (m 2 ·d)]]> Qualified Example 2 <![CDATA[0.13g / (m 2 ·d)]]> Qualified Example 3 <![CDATA[0.11g / (m 2 ·d)]]> Qualified Comparative Example 1 <![CDATA[0.34g / (m 2 ·d)]]> Qualified Comparative Example 2 <![CDATA[0.14g / (m 2 ·d)]]> Qualified

[0181] From the test results in Table 1, for the packaging films of Examples 1 - 3 of the present application, compared with the packaging film without a non-metallic waterproof layer in Comparative Example 1, the water vapor transmission rate is lower, and it has more excellent waterproof performance. For the packaging films of Examples 1 - 3 of the present application, compared with the aluminum-plastic film in Comparative Example 2, the water vapor transmission rate and the battery drop performance are comparable, meeting the performance requirements for the outer packaging film of the sealed packaged battery core.

[0182] As Figures 3 - 6 shown, the packaging films of the examples and comparative examples are respectively subjected to side sealing and top sealing of the battery core using the same heat sealing equipment, where the heat sealing width is uniformly 3mm, the heat sealing pressure is uniformly 0.3Mpa, and the heat sealing time is uniformly 3s. Among them, the heat sealing thickness of the packaging film is the thickness of the single-layer packaging film, that is, half of the thickness of the double-layer packaging film after heat sealing.

[0183] Table 2 Performance detection of packaging films at different temperatures in each example and comparative example

[0184]

[0185] Table 3 Performance detection of packaging films under different hot pressing intensities in each example and control example

[0186]

[0187] Please refer to the data in Examples 1-3 and Comparative Example 2. The packaging films of Examples 1-3 of the present application can achieve greater encapsulation strength (encapsulation strength ≥ 57 N / 15 mm, and the tensile strength of the packaging film itself is 57 N / 15 mm) under the conditions of a relatively low temperature (about 175 °C), a relatively short time (2 s), and a relatively low hot pressing air pressure (0.2 MPa) compared with the aluminum-plastic film of Comparative Example 2. The packaging films of Examples 1-3 of the present application have an initial overall thickness ≤ 50 μm and a heat-sealing thickness ≤ 45 μm compared with the aluminum-plastic film of Comparative Example 2. This significantly reduces the thickness and surface density of the battery packaging film, and the thickness of the packaging film can be further reduced after heat-sealing. As described above, the energy density of the battery can be significantly improved.

[0188] In addition, when the side-sealing and top-sealing processes are performed on the packaging film, compared with the aluminum-plastic film of Comparative Example 2, the packaging film of the present application is an overall flexible organic film, and its requirements for heat-sealing temperature, heat-sealing pressure, and heat-sealing time are lower. Further, since the packaging film of the present application is an overall flexible organic film, the fitting effect between the packaging film and the tab glue during top-sealing is better, and the tensile strength of the top-sealing part is large.

[0189] The components and devices involved in the present application are only illustrative examples and do not intend to require or imply that they must be connected, arranged, and configured in the manner shown in the drawings. As those skilled in the art will recognize, these components and devices can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open-ended words, meaning "including but not limited to", and can be used interchangeably with each other. The words "or" and "and" used herein refer to the word "and / or", and can be used interchangeably with each other unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to", and can be used interchangeably with each other.

[0190] It should also be noted that in the device of the present application, each component can be disassembled and / or recombined. These disassembly and / or recombination should be regarded as equivalent solutions of the present application.

[0191] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects are very obvious to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but to the broadest scope consistent with the principles and novel features disclosed herein.

[0192] The foregoing description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

[0193] The foregoing is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the present application shall be included within the protection scope of the present application.

Claims

1. A packaging film, characterized in that, It is composed of a first organic film layer (1) and a second organic film layer (2); The first organic film layer (1) includes a wear-resistant layer (11); The second organic film layer (2) includes a heat-melt layer; Both the first organic film layer (1) and the second organic film layer (2) include a non-metallic waterproof layer; the non-metallic waterproof layer of the second organic film layer (2) can adsorb the moisture passing through the first organic film layer (1) to prevent the moisture from passing through the second organic film layer (2).

2. The packaging film according to claim 1, wherein The wear-resistant layer (11) includes any one of nylon, polychlorotrifluoroethylene, polyethylene terephthalate, saturated polyester, and fluorinated ethylene propylene copolymer; and / or, At least one surface of the wear-resistant layer (11) is provided with a polymer coating (12), and the polymer coating (12) forms the non-metallic waterproof layer.

3. The packaging film according to claim 2, wherein The polymer coating (12) is a parylene coating; and / or, The thickness of the polymer coating (12) is H2, and 10 nm ≤ H2 ≤ 1000 nm.

4. The packaging film according to claim 1, characterized in that, The second organic film layer (2) is composed of a first layer (21), a non-metallic waterproof layer, and a second layer (23) stacked in sequence; Both the first layer (21) and the second layer (23) are the heat-melt layers; The non-metallic waterproof layer includes a water-swellable functional polymer.

5. The packaging film according to claim 4, wherein Both the first layer (21) and the second layer (23) are polyacrylic acid-styrene copolymers; and / or, The thickness of the second organic film layer (2) is H3, and 20 μm ≤ H3 ≤ 50 μm; and / or, The heat-melt temperature of the second organic film layer (2) is T3, and 165 °C ≤ T3 ≤ 170 °C.

6. The packaging film according to claim 1, wherein The thickness of the wear-resistant layer (11) is H1, and 10 μm ≤ H1 ≤ 30 μm; and / or, The melting temperature of the wear-resistant layer (11) is T1, and 170 °C ≤ T1 ≤ 300 °C.

7. The packaging film according to claim 1, wherein The water vapor transmission rate of the packaging film ≤ 0.2 g / (m 2 .d); and / or, The thickness of the packaging film ≤ 50 μm.

8. The packaging film according to claim 1, wherein, A bonding agent (3) is provided between the first organic film layer (1) and the second organic film layer (2); the thickness of the bonding agent (3) is H4, and 1 μm ≤ H4 ≤ 9 μm.

9. A battery, characterized in that, It includes an electric core and a packaging film (4) for encapsulating the electric core. The packaging film (4) is the packaging film according to any one of claims 1-8; the heat-sealing temperature of the packaging film (4) is T, the heat-sealing thickness of the packaging film (4) is H, the heat-sealing air pressure is P, and the heat-sealing time is t, where: T3 + T3×(H1 + H3) / (0.68P×1.12t) ≤ T ≤ T1; and / or, H1×(1 - 0.02P) + H3×(1 - 0.3P*T) + H2 + H4 ≤ H ≤ H1 + H2 + H3 + H4; and / or, T3 ≤ T ≤ T1; and / or, H ≤ 50 μm.

10. The battery according to claim 9, characterized in that, The packaging film (4) includes a top seal portion (41) and a side seal portion (42); the battery cell includes tab ears (5) extending out of the top seal portion (41). Along the thickness direction of the battery cell, tab ear adhesives (6) are adhered to both side surfaces of the tab ears (5), and the tab ear adhesives (6) are heat-sealed to the top seal portion (41), where: Along the center of the battery cell to the edge of the battery cell, the width of the top seal portion (41) is W1, and 1.5 mm ≤ W1 ≤ 4 mm; and / or, Along the center of the battery cell to the edge of the battery cell, the width of the side seal portion (42) is W2, and 1.5 mm ≤ W2 ≤ 4 mm; and / or, The top seal heat-sealing strength of the top seal portion (41) is S1, and S1 ≥ 35 N / 15 m; and / or, The side seal heat-sealing strength of the side seal portion (42) is S2, and S2 ≥ 35 N / 15 m; and / or, Along the extension direction of the top seal portion (41), the width of the tab ear (5) is W3, and 2.5 mm ≤ W3 ≤ 3.5 mm; and / or, Along the thickness direction of the battery cell, the thickness of the tab ear (5) is D1, and 0.05 mm ≤ D1 ≤ 0.1 mm; and / or, Along the extension direction of the top seal portion (41), the width of the tab ear adhesive (6) is W4, and 3.5 mm ≤ W4 ≤ 4.5 mm; and / or, Along the extension direction of the tab ear (5), the length of the tab ear adhesive (6) is L, and 2 mm ≤ L ≤ 5 mm; and / or, Along the thickness direction of the battery cell, the thickness of the tab ear adhesive (6) is D2, and 0.045 mm ≤ D2 ≤ 0.065 mm.

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