Battery

Abstract

The utility model provides a battery which comprises a battery cell and a high-molecular polymer membrane shell, the high-molecular polymer membrane shell comprises a body part and an edge sealing part connected to at least one side of the body part, a closed cavity is formed in the body part, and the battery cell is contained in the closed cavity; in the thickness direction of the body part, the distance between the joint of the edge sealing part and the body part and the edge of any side of the body part is A, the thickness of the body part is B, and A and B meet the condition that A / B is larger than or equal to 0.25 and smaller than or equal to 0.75. The edge sealing part of the high-molecular polymer film shell is arranged at the specific position in the thickness direction of the battery cell, so that the residual volume of the battery cell wrapped by the battery packaging film can be reduced to the maximum extent, and the ED of the battery is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of battery devices, and in particular to a battery. Background Art

[0002] Traditional soft-pack lithium-ion battery packaging film usually uses aluminum-plastic film, which is mainly composed of a three-layer structure of organic anti-friction layer / metal aluminum foil layer / organic heat-sealing layer. The method of encapsulating battery cells is, in order, punching holes, discharging cells, applying hot melt adhesive to the cell surface, top / side heat sealing, and folding edges. Among them, the aluminum-plastic film with a metal aluminum foil layer is prone to corner breakage during the punching and cell encapsulation process, especially in high-expansion battery types (such as silicon negative electrode lithium-ion batteries, lithium-sulfur batteries, etc.), and the punching of the aluminum-plastic film often leaves a large volume margin to allow the battery cell to be placed in the punching hole of the aluminum-plastic film, but this also leads to a decrease in the battery's volume energy density (ED). In addition, the aluminum foil layer in the aluminum-plastic film not only has the risk of corrosion, but the presence of the aluminum foil layer also makes it impossible to excessively thin the aluminum-plastic film, which also greatly reduces the battery's ED. Utility Model Content

[0003] The present application provides a battery, in which the edge sealing portion of the polymer film shell of the battery is located at a specific position in the thickness direction of the battery cell, reducing the remaining volume of the battery packaging film wrapped around the battery cell, thereby reducing the battery ED loss.

[0004] In detail, the present application provides a battery comprising a battery cell and a polymer membrane shell, wherein the polymer membrane shell comprises a main body portion and an edge sealing portion connected to at least one side of the main body portion, a sealed cavity is formed inside the main body portion, and the battery cell is accommodated in the sealed cavity;

[0005] Along the thickness direction of the main body, the distance between the connection between the edge sealing portion and the main body and any side edge of the main body is A, and the thickness of the main body is B, wherein A and B satisfy: 0.25≤A / B≤0.75.

[0006] In an optional implementation manner, A and B satisfy: A / B=0.5.

[0007] In an optional embodiment, the polymer membrane shell includes a straight section and an arc section adapted to the surface of the battery cell, and the two arc sections are located on both sides of the straight section;

[0008] Along the thickness direction of the main body, the arc length of the arc segment is C, and the width of the edge sealing portion is D, wherein C and D satisfy: D≤0.5C.

[0009] In an optional embodiment, the polymer film shell includes an anti-friction layer, an insulation layer, and a heat-sealing layer stacked in sequence;

[0010] The anti-friction layer is located on a side of the heat sealing layer facing away from the battery core.

[0011] In an optional embodiment, the thickness of the anti-friction layer is greater than or equal to 12 μm and less than or equal to 50 μm; and / or

[0012] The thickness of the insulating layer is greater than or equal to 12 μm and less than or equal to 30 μm; and / or,

[0013] The thickness of the heat-sealing layer is greater than or equal to 10 μm and less than or equal to 50 μm.

[0014] In an optional embodiment, an adhesive layer is provided between the anti-friction layer and the insulating layer, and an adhesive layer is also provided between the insulating layer and the heat-sealing layer, and the thickness of the adhesive layer is greater than or equal to 2 μm and less than or equal to 10 μm; and / or,

[0015] The peel strength between the anti-friction layer and the insulating layer and the peel strength between the insulating layer and the heat-sealing layer are greater than or equal to 1.5 N / 15 mm.

[0016] In an optional embodiment, the water vapor transmission rate of the polymer membrane shell is ≤0.1 g / (m 2 ·d).

[0017] In an optional embodiment, the edge sealing portion is attached to a side surface of the main body portion; and / or,

[0018] The battery further includes an adhesive layer. The edge sealing portion is attached to a side surface of the main body portion. The adhesive layer is respectively bonded to the edge sealing portion and the main body portion.

[0019] In an optional embodiment, a hot melt adhesive layer is provided between the battery core and the polymer membrane shell, the thickness of the hot melt adhesive layer is h, and the thickness of the polymer membrane shell is H, wherein H and h satisfy: 0.1H≤h≤0.5H.

[0020] In an optional embodiment, the thickness of the high molecular polymer membrane shell is H, wherein H satisfies: H≤75 μm.

[0021] In this application, a polymer film shell is used instead of the traditional aluminum-plastic film. Since the polymer has greater elasticity than the aluminum-plastic film, the residual volume of the packaging film wrapped around the battery cell can be reduced to the greatest extent, thereby helping to reduce the ED loss of the battery. Moreover, the polymer film layer can effectively isolate moisture and has better corrosion resistance, which can solve the problem of easy corrosion of the aluminum layer in the battery aluminum-plastic film packaging film shell in the prior art. In addition, this application also stipulates that the connection between the edge sealing part and the main body is set at a specific position in the thickness direction of the battery cell, which can further reduce the residual volume of the battery packaging film after wrapping the battery cell, thereby further reducing the ED loss of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0023] Figure 1 This is a schematic structural diagram of a battery according to a specific embodiment of the present application;

[0024] In the figure, 1: sealed cavity, 2: main body, 3: edge sealing, 4: hot melt adhesive layer, A: distance between the connection between the edge sealing and the main body and any side edge of the main body, B: thickness of the main body, C: position of the arc segment of the polymer membrane shell, D: width of the edge sealing;

[0025] Figure 2 This is a schematic structural diagram of a battery according to a specific embodiment of the present application before the edge sealing portion is folded;

[0026] In the figure, 1: sealed cavity, 2: main body, 3: edge sealing, 4: hot melt adhesive layer, C: location of the arc segment of the polymer membrane shell, D: width of the edge sealing;

[0027] Figure 3 A schematic structural diagram of a battery according to a specific embodiment of the present application;

[0028] In the figure, 1: sealed cavity, 2: main body, 3: edge sealing, 4: hot melt adhesive layer, a: semi-major axis of the battery cell arc, b: semi-minor axis of the battery cell arc;

[0029] Figure 4 These are SEM images of the polymer membrane shell of Example 1 of the present application; (a) is an SEM image of the main body of the polymer membrane shell before hot pressing, and (b) is an SEM image of the edge sealing portion of the polymer membrane shell after hot pressing;

[0030] Figure 5 Schematic diagram of the structure of the battery of Comparative Example 1;

[0031] In the figure, 3: edge sealing part, 4: hot melt adhesive layer;

[0032] Figure 6 This is a schematic structural diagram of the battery of Comparative Example 1 before the edge sealing portion is folded;

[0033] In the figure, 1: sealed cavity, 2: main body, 3: edge sealing part, 4: hot melt adhesive layer.

[0034] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be understood that the following embodiments are only illustrative illustrations and explanations of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above contents of the present invention are included in the scope that the present invention is intended to protect. In the drawings, parts with the same structure are represented by the same numerical labels, and components with similar structures or functions are represented by similar numerical labels. The size and thickness of each component shown in the drawings are shown arbitrarily, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of the components is appropriately exaggerated in some places in the drawings.

[0036] The same or similar numbers in the drawings of the embodiments of the present application correspond to the same or similar parts; in the description of the present application, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. This is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or component referred to must have a specific direction. It is constructed and operated in a specific direction. Therefore, the terms describing the positional relationships in the drawings are only used for illustrative purposes and cannot be understood as limiting the present application. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0037] The present application provides a battery, Figure 1 This is a schematic diagram of a battery structure according to a specific embodiment of the present application, comprising a battery cell and a polymer membrane shell. The polymer membrane shell comprises a main body 2 and an edge sealing portion 3 connected to at least one side of the main body. A sealed cavity 1 is formed inside the main body, and the battery cell is accommodated in the sealed cavity.

[0038] Along the thickness direction of the main body, the distance between the connection between the edge sealing portion and the main body and any side edge of the main body is A, and the thickness of the main body is B, wherein A and B satisfy: 0.25≤A / B≤0.75.

[0039] To address the problem of reduced battery ED (Energy Efficiency) caused by the use of aluminum-plastic film in traditional soft-pack lithium-ion battery packaging films, this application uses a polymer film shell in place of aluminum-plastic film. Compared to conventional aluminum-plastic film, polymers have greater elasticity, which can minimize the residual volume of the packaging film after wrapping the battery cell, thereby reducing battery ED loss. Furthermore, the polymer film layer effectively isolates moisture and offers improved corrosion resistance, resolving the issue of aluminum layer corrosion susceptibility in existing battery aluminum-plastic films. Furthermore, this application further reduces the residual volume of the battery packaging film after wrapping the battery cell by limiting the distance A between the junction of the edge seal and the main body and the edge of either side of the main body to B, with the thickness of the main body being 0.25 ≤ A / B ≤ 0.75, thereby further helping to reduce battery ED loss.

[0040] The connection between the edge seal and the main body is located in the middle of the thickness of the main body, which can minimize the remaining volume of the main body after the battery packaging film wraps the battery cell. Therefore, in order to further reduce the ED loss of the battery, in some embodiments, A and B satisfy: A / B=0.5. The connection position relationship between the edge seal and the main body of these embodiments can be specifically referred to. Figure 2 ,Depend on Figure 2 It can be clearly seen that the edge sealing portion connects the main body portion at the middle position in the thickness direction of the battery cell.

[0041] In some embodiments, the polymer film shell of the present application can be formed by folding a transparent film around the battery cell, and has three edge seals, namely, two side edge seals and a bottom edge seal. In this case, the connection between the edge seals and the main body refers to the connection between the two side edge seals and the main body.

[0042] In other embodiments, the polymer membrane shell of the present application is formed by stacking two transparent films on top of each other, and in this case, it has four edge seals, namely, the connection between the edge seals and the main body. In this case, the connection between the edge seals and the main body refers to the connection between the two side edge seals and the main body.

[0043] In some embodiments, the polymer membrane shell includes a straight section and an arc section adapted to the surface of the battery cell, and the two arc sections are located on both sides of the straight section;

[0044] Along the thickness direction of the main body, the arc length of the arc segment is C, and the width of the edge sealing portion is D, wherein C and D satisfy: D≤0.5C.

[0045] Among them, the periphery of the battery cell is composed of a straight section and a part of an arc section similar to an ellipse or a circle. Therefore, the polymer film shell correspondingly includes a straight section and an arc section adapted to the surface of the battery cell. Along the thickness direction of the main body, the arc length of the arc section is C, and the width of the edge sealing portion is D. C and D satisfy: D≤0.5C, which can reduce the remaining volume after the battery cell is wrapped by the battery packaging film to a certain extent, thereby helping to further reduce the ED loss of the battery.

[0046] In one embodiment, the arc segment of the cell periphery is similar to a portion of an ellipse. Figure 3 At this time, the arc length of the arc segment of the polymer membrane shell is C=(π·b)+2(ab), where a is the semi-major axis of the cell arc, that is, the vertical distance from the vertex of the cell arc to the cell body, unit: μm, and b is the semi-minor axis of the cell arc, that is, half of the cell thickness.

[0047] For example, when the cell thickness is ≤10 mm, 0<b≤5 mm. Specifically, b is 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, etc.

[0048] In another specific embodiment, the arc segment of the battery cell periphery is similar to a portion of a circle. In this case, the arc length of the arc segment is C=π·r, where r is the axial length of the battery cell arc, which is numerically equal to the thickness B of the main body.

[0049] In some embodiments, the polymer film shell includes an anti-friction layer, an insulation layer, and a heat-sealing layer stacked in sequence;

[0050] The anti-friction layer is located on a side of the heat sealing layer facing away from the battery core.

[0051] Among them, the anti-friction layer mainly plays a role in high wear resistance and high corrosion resistance of the battery. In a specific embodiment, the material of the anti-friction layer includes one or more of polyamide polymers, polyvinyl fluoride polymers, saturated polyester polymers, and fluorinated ethylene propylene copolymers.

[0052] The insulating layer mainly plays the role of high corrosion resistance and barrier to moisture / electrolyte. In a specific embodiment, the material of the insulating layer includes one or more of polyvinyl fluoride polymers, polyvinyl chloride polymers, and enol polymers.

[0053] The heat-sealing layer mainly plays a role in high resistance to battery electrolyte corrosion and easy welding. In a specific embodiment, the material of the heat-sealing layer includes polypropylene and / or modified polypropylene.

[0054] In some embodiments, the thickness of the anti-friction layer is greater than or equal to 12 μm and less than or equal to 50 μm; and / or,

[0055] The thickness of the insulating layer is greater than or equal to 12 μm and less than or equal to 30 μm; and / or,

[0056] The thickness of the heat-sealing layer is greater than or equal to 10 μm and less than or equal to 50 μm.

[0057] Among them, the thickness of the anti-friction layer is greater than or equal to 12μm, which can provide basic wear resistance and corrosion resistance protection, making the polymer membrane shell suitable for more harsh use environments, while the thickness of the anti-friction layer is less than or equal to 50μm, which can maintain the flexibility of the membrane shell, reduce material usage, and reduce manufacturing costs; the thickness of the insulation layer is greater than or equal to 12μm, which can more effectively isolate the chemical substances inside the battery, prevent unnecessary chemical reactions, and provide better electrical insulation performance, prevent internal short circuits in the battery, and improve safety. However, if the insulation layer is too thick, it will occupy the space inside the battery, reduce the volume of active materials, and thus reduce the energy of the battery. Density, therefore, the thickness of the insulation layer is less than or equal to 30μm, which can better balance the relationship between battery safety and energy density; the thickness of the heat sealing layer is greater than or equal to 10μm, which can provide stronger sealing performance, ensure the air tightness and liquid tightness of the battery, prevent electrolyte leakage, and provide better adhesion and strength during the heat sealing process to ensure the firmness of the seal; however, if the thickness of the heat sealing layer is too thick, higher heat sealing temperature and pressure may be required, which increases the complexity and difficulty of the heat sealing process. Therefore, the thickness of the heat sealing layer is less than or equal to 50μm, which can ensure the heat sealing performance of the heat sealing layer while avoiding the negative impact of the excessive thickness of the heat sealing layer.

[0058] Exemplarily, the thickness of the anti-friction layer is 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, etc.; and / or the thickness of the insulating layer is 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, etc.; the thickness of the heat sealing layer is 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, etc.

[0059] In some embodiments, an adhesive layer is provided between the anti-friction layer and the insulating layer, and an adhesive layer is also provided between the insulating layer and the heat-sealing layer, and the thickness of the adhesive layer is greater than or equal to 2 μm and less than or equal to 10 μm; and / or,

[0060] The peel strength between the anti-friction layer and the insulating layer and the peel strength between the insulating layer and the heat-sealing layer are greater than or equal to 1.5 N / 15 mm.

[0061] The main function of the above-mentioned adhesive layer is to enhance the thickness of the adhesive layer to be greater than or equal to 2 μm and less than or equal to 10 μm, which can provide better adhesion and buffering effect between the friction layer and the insulation layer, and between the insulation layer and the heat sealing layer. Among them, better adhesion can ensure that the anti-friction layer and the insulation layer, and between the insulation layer and the heat sealing layer will not separate during use, and the buffering effect can absorb and disperse external stress, and play a role in protecting the anti-friction layer, the insulation layer and the heat sealing layer; when the peel strength between the anti-friction layer and the insulation layer and the peel strength between the insulation layer and the heat sealing layer are greater than or equal to 1.5 N / 15 mm, the durability of the polymer membrane shell can be further improved to ensure its reliability in practical applications.

[0062] In one specific embodiment, the battery of the present application is a spiral wound battery, which includes a battery core, a polymer film shell encapsulating the battery core, and an electrolyte. The battery core is formed by winding or stacking a positive electrode sheet, a separator, and a negative electrode sheet in sequence. More specifically, the preparation process of the battery core is described using a 462030Q-380mAh / 1.486Wh soft-pack lithium-ion battery as an example:

[0063] 1) The positive electrode active material, conductive agent, binder and solvent are mixed uniformly and then coated on the surface of the positive electrode substrate to obtain a positive electrode sheet; wherein the specification of the positive electrode substrate is selected as 8 μm aluminum foil; the prepared electrode sheet is dried and roll-pressed to obtain a positive electrode sheet; the negative electrode active material graphite, conductive agent, binder and solvent are mixed uniformly and then coated on the surface of the negative electrode substrate to obtain a negative electrode sheet; wherein the specification of the negative electrode substrate is selected as 6 μm copper foil; the prepared electrode sheet is dried and roll-pressed to obtain a negative electrode sheet;

[0064] 2) Weld the positive electrode tab to the empty aluminum foil and the negative electrode tab to the empty copper foil, and wind them together with the separator to obtain the battery core.

[0065] As for the above-mentioned high molecular polymer film shell, it can be packaged and wrapped with battery core and electrolyte through a high temperature hot pressing process. The specific packaging method is in the following order: placing the battery core, sticking hot melt glue on the core surface, top / side heat sealing, liquid injection, aging, formation, secondary sealing, and folding (bending). That is, the high molecular polymer film shell of this application does not need to be punched in advance, and the battery cell can be directly packaged in a non-formed center. The packaging process is a hot pressing packaging process; wherein, the sealing edge and the packaging film can be fixed by a dispensing process.

[0066] In some embodiments, the water vapor transmission rate of the polymer membrane shell is ≤0.1 g / (m 2 d). The high molecular polymer membrane shell with high water vapor transmission rate can prevent external water vapor from penetrating into the battery, thereby ensuring the normal use of the battery cell.

[0067] In some embodiments, the edge sealing portion is attached to a side surface of the main body portion; and / or,

[0068] The battery further includes an adhesive layer. The edge sealing portion is attached to a side surface of the main body portion. The adhesive layer is respectively bonded to the edge sealing portion and the main body portion.

[0069] The polymer membrane shell of the present application, its film forming process includes but is not limited to one or more of compression molding, injection molding, and extrusion molding. Exemplarily, the film is formed by a method including the following process:

[0070] 1) Anti-friction layers, insulation layers, and heat-sealing layers of different thicknesses and materials can be prepared through compression molding, injection molding, or co-extrusion molding processes;

[0071] 2) The surfaces of each layer contacting the adhesive are subjected to corona treatment;

[0072] 3) Applying an adhesive between the adjacent film layers obtained above, and baking at 65° C. to obtain the polymer film shell.

[0073] In order to further make the polymer film shell fit the battery cell to meet the battery drop test, in some embodiments, a hot melt adhesive layer is provided between the battery cell and the polymer film shell, the thickness of the hot melt adhesive layer is h, and the thickness of the polymer film shell is H, wherein H and h satisfy: 0.1H≤h≤0.5H.

[0074] As for the material of the hot melt adhesive layer, this application does not make any special limitation. For example, the material of the hot melt adhesive layer is one or more of ethylene-vinyl acetate copolymer, moisture-reactive polyurethane hot melt adhesive, polyolefin, and styrene block copolymer.

[0075] The thickness of the battery polymer membrane shell is relatively thin, which is beneficial to further improve the battery ED. In a specific embodiment, the thickness of the polymer membrane shell is H, where H satisfies: H≤75μm.

[0076] The present application is further described below with reference to specific embodiments:

[0077] Example 1

[0078] This example provides a battery, the structural diagram of which is shown in Figure 1, comprising a battery cell and a polymer membrane shell, the polymer membrane shell comprising a main body 2 and an edge sealing portion 3 connected to both sides of the main body, a closed cavity 1 is formed inside the main body, and the battery cell is accommodated in the closed cavity; along the thickness direction of the main body, the distance between the connection between the edge sealing portion and the main body and the edge of any side of the main body is A, and the thickness of the main body is B, wherein A and B satisfy: A / B=0.5 (see Figure 2 ), the polymer membrane shell includes a straight section and an arc section adapted to the surface of the battery cell, and the two arc sections are located on both sides of the straight section; the semi-major axis dimension a of the battery cell arc section is 2.2 mm, and the semi-minor axis length b of the battery cell arc section is 2 mm; along the thickness direction of the main body, the arc length of the arc section is C, C=6.68 mm, and the width of the edge sealing portion is D, D=1.5 mm; the battery also includes an adhesive layer, the edge sealing portion is attached to one side surface of the main body, and the adhesive layer respectively bonds the edge sealing portion and the main body;

[0079] The polymer membrane shell is stacked from the outside to the inside with an anti-friction layer with a thickness of 12μm (polytrifluorochloroethylene film), an insulating layer (polyethylene terephthalate) with a thickness of 15μm, and a heat-sealing layer (polypropylene film) with a thickness of 30μm; each two layers are fixed by an adhesive layer (polyurethane adhesive with a thickness of 4.5μm). The thickness of the main body of the polymer membrane shell is 52.5μm, and the thickness of the edge sealing part is 0.105mm. A hot melt adhesive layer 4 is provided between the battery cell and the polymer membrane shell, and the thickness of the hot melt adhesive layer 4 is 12μm.

[0080] The battery preparation process includes: preparing a 462030Q-380mAh / 1.486Wh model soft-pack lithium-ion battery cell, placing the cell on the main body of the polymer film shell, applying hot melt adhesive ethylene-vinyl acetate copolymer to the cell surface, top / side heat sealing, liquid injection, aging, formation, secondary sealing, and folding steps, and finally obtaining a 462030Q-380mAh / 1.486Wh lithium-ion battery with a voltage of 4.5V. In the top / side heat sealing process, the hot pressing temperature is 180°C, the hot pressing pressure is 0.3MPa, and the hot pressing time is 3s. The initial polymer film shell thickness is 66μm, and the microscopic picture is shown in FIG. Figure 4 In (a), two layers of polymer film shells are hot-pressed when encapsulating the battery cell. The thickness of the edge is 132μm. The thickness of the edge after hot pressing is 0.105mm (see the microscopic picture). Figure 4 In (b), the thickness of the polymer membrane shell body after hot pressing is 52.5 μm. The width of the hot pressing packaging, that is, the width of the edge sealing part, is less than half the length of the battery cell arc. The edge sealing part and the battery polymer membrane shell are fixed by a dispensing process.

[0081] Comparative Example 1

[0082] This example provides a battery, the structural diagram of which is shown in Figure 4 , including a battery cell and a thick Showa aluminum-plastic film shell, the thick Showa aluminum-plastic film shell includes a main body and a sealing edge 3 connected to one side of the main body 2, a sealed cavity 1 is formed inside the main body, and the battery cell is accommodated in the sealed cavity; the battery also includes an adhesive layer, the sealing edge is attached to one side surface of the main body, and the adhesive layer respectively bonds the sealing edge and the main body. Figure 6 Schematic diagram of the structure of the edge sealing portion of the aluminum-plastic film packaging film before being attached; wherein, the width of the edge sealing portion, the semi-major axis dimension a of the battery cell arc, and the semi-minor axis length b of the battery cell arc are the same as those in Example 1, the folding edge thickness is 0.155 mm, and the thickness of the aluminum-plastic film packaging film is 86 μm;

[0083] The aluminum-plastic film packaging film is composed of an anti-friction layer with a thickness of 17 μm (polytrifluorochloroethylene film), an aluminum foil layer with a thickness of 30 μm, and a heat-sealing layer (polypropylene film) with a thickness of 30 μm from the outside to the inside; each two film layers are fixed by an adhesive layer (polyurethane adhesive with a thickness of 4.5 μm), and a hot melt adhesive layer 4 with a thickness of 12 μm is also provided between the battery cell and the aluminum-plastic film packaging film.

[0084] The preparation process of the battery includes: preparing a 462030Q-380mAh / 1.486Wh model soft-pack lithium-ion battery cell consistent with Example 1, punching, discharging the cell, applying hot melt adhesive to the cell surface, top / side heat sealing, liquid injection, aging, formation, secondary sealing, and folding, and then obtaining a model 462030Q-380mAh / 1.486Wh lithium-ion battery with a voltage of 4.5V. The aluminum-plastic film wraps the cell and adopts punching packaging. During the packaging process, there is a lot of free volume between the aluminum-plastic film and the cell. In order to consider the impact resistance of the battery in response to external forces during transportation and carrying, the thickness of the hot melt adhesive attached to the cell surface is selected to be 28μm; in the process of hot-pressing the cell with aluminum-plastic film, the hot-pressing temperature is 180°C, the hot-pressing air pressure is 0.3MPa, the hot-pressing time is 3s, and the folding thickness is 0.155mm. The width of the hot-pressing packaging, that is, the width of the battery sealing edge is less than the battery thickness, such as Figure 5 The edge sealing part is attached to the main body of the aluminum-plastic film, and the edge sealing part and the main body are fixed by using a dispensing process.

[0085] Comparative Example 2

[0086] The same as Comparative Example 1, except that: a 113 μm thick aluminum-plastic packaging film is selected, and the thickness of the sealed edge is 0.212 mm; the aluminum-plastic packaging film is sequentially stacked from the outside to the inside with an anti-friction layer with a thickness of 24 μm (polytrifluorochloroethylene film), an aluminum foil layer with a thickness of 50 μm, and a heat-sealing layer (polypropylene film) with a thickness of 30 μm; each two film layers are fixed by an adhesive layer (polyurethane adhesive, 4.5 μm); the battery preparation process refers to Comparative Example 1.

[0087] The thickness changes of the edge sealing parts of the above Example 1 and Comparative Examples 1 and 2 during the hot pressing process are summarized in Table 1.

[0088] Table 1:

[0089]

[0090] As can be seen from Table 1, the polymer film shell of Example 1 and the aluminum-plastic films of Comparative Examples 1 and 2 will both be hot-melted and thinned during the heat sealing process. Compared with the aluminum-plastic films of Comparative Examples 1 and 2, since the polymer film shell of Example 1 does not contain an aluminum foil layer, it will not cause a large difference in the temperature of the head and the organic heat-sealing layer due to metal heat conduction during hot pressing packaging, so that the organic polymer heat-sealing layer of the polymer film shell has a better hot-melt effect and the packaging film layer is thinned more.

[0091] Battery drop test:

[0092] The conventional lithium cobalt oxide soft-pack batteries prepared in Example 1 and Comparative Example 1 were subjected to a 1.2-meter drop test in accordance with the standards SJ / T 11169-1998 "Standard Drop Test for Lithium Batteries" and GB 31241-2014 "Drop Test" to examine the impact resistance of the lithium-ion batteries in response to external forces during transportation and carrying. The results are summarized in Table 2.

[0093] Table 2:

[0094]

[0095] As can be seen from Table 2, the batteries of Example 1 and the comparative example both meet the battery drop test, but the hot melt adhesive used in Example 1 is thinner.

[0096] Battery volume energy density test:

[0097] Volume energy density (Wh / L) = battery capacity (mAh) × discharge platform voltage (V) / (thickness (cm) Width (cm) Length (cm)). The battery capacity and discharge platform voltage in the embodiment and the comparative example are the same. Therefore, only the difference in battery volume is considered. The test results are summarized in Table 3:

[0098] Table 3:

[0099]

[0100] It can be seen from Table 3 that, compared with Comparative Examples 1 and 2, the battery of Example 1 can minimize the remaining volume of the battery cell wrapped by the battery packaging film, thereby further improving the ED of the battery.

[0101] It should be understood that the present application is not limited to the exact structure described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A battery, characterized in that: The battery cell comprises a battery cell and a polymer membrane shell, wherein the polymer membrane shell comprises a main body and an edge sealing portion connected to at least one side of the main body, a sealed cavity is formed inside the main body, and the battery cell is accommodated in the sealed cavity; Along the thickness direction of the main body, the distance between the connection between the edge sealing portion and the main body and any side edge of the main body is A, and the thickness of the main body is B, wherein A and B satisfy: 0.25≤A / B≤0.

75.

2. The battery according to claim 1, characterized in that A and B satisfy: A / B=0.

5.

3. The battery according to claim 1, characterized in that The polymer membrane shell includes a straight section and an arc section adapted to the surface of the battery cell, and the two arc sections are located on both sides of the straight section; Along the thickness direction of the main body, the arc length of the arc segment is C, and the width of the edge sealing portion is D, wherein C and D satisfy: D≤0.5C.

4. The battery according to claim 1, characterized in that The polymer film shell comprises an anti-friction layer, an insulating layer and a heat-sealing layer stacked in sequence; The anti-friction layer is located on a side of the heat sealing layer facing away from the battery core.

5. The battery according to claim 4, characterized in that The thickness of the anti-friction layer is greater than or equal to 12 μm and less than or equal to 50 μm; and / or, The thickness of the insulating layer is greater than or equal to 12 μm and less than or equal to 30 μm; and / or, The thickness of the heat-sealing layer is greater than or equal to 10 μm and less than or equal to 50 μm.

6. The battery according to claim 4, characterized in that An adhesive layer is provided between the anti-friction layer and the insulating layer, and an adhesive layer is also provided between the insulating layer and the heat-sealing layer, and the thickness of the adhesive layer is greater than or equal to 2 μm and less than or equal to 10 μm; and / or, The peel strength between the anti-friction layer and the insulating layer and the peel strength between the insulating layer and the heat-sealing layer are greater than or equal to 1.5N / 15mm.

7. The battery according to claim 1, characterized in that The water vapor permeability of the polymer membrane shell is ≤0.1g / (m 2 ·d).

8. The battery according to claim 1, characterized in that The edge sealing portion is attached to a side surface of the main body portion; and / or, The battery further includes an adhesive layer. The edge sealing portion is attached to a side surface of the main body portion. The adhesive layer is respectively bonded to the edge sealing portion and the main body portion.

9. The battery according to any one of claims 1 to 8, characterized in that: A hot melt adhesive layer is provided between the battery core and the polymer membrane shell. The thickness of the hot melt adhesive layer is h, and the thickness of the polymer membrane shell is H. H and h satisfy: 0.1H≤h≤0.5H.

10. The battery according to any one of claims 1 to 8, characterized in that: The thickness of the high molecular polymer membrane shell is H, wherein H satisfies: H≤75 μm.

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