Battery pack, assembling method and disassembling method thereof, and electric device

Abstract

The present application relates to a battery pack (1), comprising: a box body (2) having an accommodating cavity (24); the battery core (3) is positioned in the accommodating cavity (24); the first insulating film (9) is adhered to the outer surface of the battery cell (3), and the first insulating film (9) at least covers the bottom surface of the battery cell (3); and the first adhesive layer (8) is positioned between the first insulating film (9) and the inner wall of the accommodating cavity (24).

Description

Battery pack, assembly method, disassembly method and power-consuming device thereof Technical Field

[0001] The present application relates to the technical field of energy storage devices, and in particular to a battery pack, an assembly method, a disassembly method, and an electrical device thereof. Background Art

[0002] To meet the insulation requirements of battery cells, they are typically coated with an insulating film. In a CTP (Cell to Pack) battery pack, the cells are bonded to the casing, eliminating the need for modular assembly. This reduces component count and increases the pack's energy density. However, the bonding strength between the insulating film on the cell's outer surface and the structural adhesive is low, failing to meet practical requirements. Improving the strength and reliability of the cells in the battery pack is a pressing issue in battery technology.

[0003] Summary of the Invention

[0004] Based on this, the present application provides a battery pack, its assembly method, disassembly method, and electrical device. In this battery pack, a first insulating film is bonded to the outer surface of the battery cell, and the first insulating film at least covers the bottom surface of the battery cell, thereby improving the bonding strength between the first insulating film and the battery cell, and between the first insulating film and the first adhesive layer, thereby improving the strength and reliability of the battery cell in the box.

[0005] In a first aspect of the present application, a battery pack is provided, comprising:

[0006] A box body having a receiving cavity;

[0007] A battery cell is located in the accommodating cavity;

[0008] a first insulating film adhered to the outer surface of the battery cell, and the first insulating film at least covers the bottom surface of the battery cell; and

[0009] The first adhesive layer is located between the first insulating film and the inner wall of the accommodating cavity.

[0010] In some embodiments, the first insulating film includes unsaturated polyester.

[0011] In some embodiments, the unsaturated polyester includes one or more of rosin-modified unsaturated polyester, para-terephthalate unsaturated polyester, bisphenol A unsaturated polyester, and vinyl unsaturated polyester.

[0012] In some embodiments, at room temperature, the interfacial bonding strength of the first insulating film is ≥7 MPa.

[0013] In some embodiments, at 60° C., the interfacial bonding strength of the first insulating film is ≥4 MPa.

[0014] In some embodiments, at 80° C., the interfacial bonding strength of the first insulating film is ≤0.3 MPa.

[0015] In some embodiments, the outer shell of the battery cell is an aluminum shell.

[0016] In some embodiments, at 80° C., the tensile elastic modulus of the first insulating film is ≤0.2 MPa.

[0017] In some embodiments, the dielectric strength of the first insulating film is ≥20 kV / mm.

[0018] In some embodiments, the thickness of the first insulating film is 25 μm to 75 μm, and can be optionally 30 μm to 50 μm.

[0019] In some embodiments, the first insulating film covers the bottom and side surfaces of the battery cell, and the first insulating film extends to the top surface of the battery cell.

[0020] In some embodiments, the maximum width of the first insulating film on the top surface of the battery cell is 3 mm to 5 mm.

[0021] In some embodiments, at room temperature, the interfacial bonding strength of the first adhesive layer is ≥7 MPa.

[0022] In some embodiments, the first adhesive layer includes structural adhesive.

[0023] In some optional embodiments, the structural adhesive includes one or more of a thermally conductive structural adhesive and a non-thermal conductive structural adhesive.

[0024] In some embodiments, the battery pack further includes an insulating cover, wherein the insulating cover is located between the battery cell and a side wall of the accommodating cavity.

[0025] In some embodiments, there are a plurality of battery cells, and adjacent battery cells, as well as the insulating cover and the battery cells, are bonded together by a second adhesive layer.

[0026] In some embodiments, the second adhesive layer includes one or more of a pressure-sensitive adhesive and a structural adhesive.

[0027] In some embodiments, the battery pack further includes an end plate, and the end plate is located on a side of the insulating cover close to the side wall of the accommodating cavity.

[0028] In some embodiments, the end plate and the insulating cover are bonded together by a third adhesive layer;

[0029] In some embodiments, the third adhesive layer includes one or more of a pressure-sensitive adhesive and a structural adhesive.

[0030] In some embodiments, the box body includes an upper box body and a lower box body, the upper box body cover is provided on the lower box body, and the upper box body and the lower box body cooperate to form the accommodating cavity.

[0031] In some embodiments, the lower housing comprises a metal material.

[0032] In some optional embodiments, the metal material includes one or more of steel and aluminum alloy.

[0033] A second aspect of the present application provides a method for assembling the battery pack according to the first aspect of the present application, comprising the following steps:

[0034] Covering the outer surface of the battery cell with the first insulating film;

[0035] The battery core covered with the first insulating film is bonded to the inner wall through the first adhesive layer.

[0036] In some embodiments, the first insulating film is coated on the outer surface of the battery cell by hot pressing.

[0037] In some embodiments, the hot pressing process conditions include: hot pressing temperature of 80° C. to 100° C., hot pressing pressure of 0.05 MPa to 0.2 MPa, and hot pressing time of 2 min to 6 min.

[0038] A third aspect of the present application provides a method for disassembling the battery pack according to the first aspect of the present application, comprising the following steps:

[0039] heating and keeping the battery pack warm;

[0040] Apply external force to the battery pack after heat preservation.

[0041] In some embodiments, the heating temperature is 70° C. to 100° C., and the insulation time is ≥15 min.

[0042] In some embodiments, the direction of applying the external force is perpendicular to the bottom surface of the battery cell.

[0043] In a fourth aspect of the present application, an electrical device is provided, which includes the battery pack described in the first aspect of the present application.

[0044] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0046] FIG1 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0047] FIG2 is a schematic diagram of a box according to an embodiment of the present application.

[0048] FIG3 is a schematic diagram of a battery cell according to an embodiment of the present application.

[0049] FIG. 4 is a schematic diagram of a first insulating film according to an embodiment of the present application.

[0050] FIG5 is a schematic diagram of a first insulating film and a second insulating film according to another embodiment of the present application.

[0051] FIG6 is a schematic diagram of a first insulating film and a second insulating film according to yet another embodiment of the present application.

[0052] FIG7 is a schematic diagram of an electrical device using a battery pack as a power source according to an embodiment of the present application.

[0053] Explanation of the accompanying numbers: 1-battery pack; 2-box; 21-upper box; 22-lower box; 23-bottom wall; 24-accommodation cavity; 3-battery cell; 4-second adhesive layer; 5-insulating cover; 6-third adhesive layer; 7-end plate; 8-first adhesive layer; 9-first insulating film; 10-second insulating film; 11-electrical device. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0055] Numerical value " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and selected lower limit and upper limit define the boundary of special range. The scope that this mode limits can be to include end value or not include end value, and any end value can be included or not included independently, and can be arbitrarily combined, and promptly any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 listed, and if also listing the maximum range value 3,4 and 5, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for a combination of these values. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", this is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0056] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0057] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, and may preferably be performed sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0058] Unless otherwise specified, the terms "having," "including," "containing," and "comprising" used in this application may each independently represent open or closed forms. For example, "including" and "comprising" may also represent other components or temporal features not listed, or may only represent the listed components or temporal features. Examples of components include materials or components, structures, elements, and instruments; non-limiting examples of temporal features include actions, conditions for the occurrence of actions, timing, and states.

[0059] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." Furthermore, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0060] In this application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0061] In this application, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more relevant listed items, and also include any and all combinations of the relevant listed items, wherein the arbitrary and all combinations include any two relevant listed items, any more relevant listed items, or a combination of all relevant listed items. For example, "A and / or B" means a group consisting of A, B, and "a combination of A and B." Among them, "including A and / or B" can mean "including A, including B, and including A and B", and can also mean "including A, including B, or including A and B", which can be appropriately understood according to the sentence in which it is located.

[0062] In this application, "a plurality of" or "a plurality of" refers to a number greater than or equal to 2 unless otherwise specified. For example, "one or more" means one or more than or equal to two.

[0063] In this application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0064] In this application, the terms "first," "second," "third," "fourth," etc. in "the first aspect," "the second aspect," "the third aspect," "the fourth aspect," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the indicated technical features. Furthermore, "first," "second," "third," "fourth," etc. serve only as non-exhaustive enumeration and description, and should be understood not to constitute a closed-ended limitation on quantity.

[0065] In this application, the horizontal direction is the direction parallel to the horizontal plane, which can be either the above-mentioned length direction or the above-mentioned width direction. In addition, the horizontal direction not only includes the direction absolutely parallel to the horizontal plane, but also includes the direction roughly parallel to the horizontal plane conventionally recognized in engineering. The vertical direction is the direction perpendicular to the horizontal plane, which can be either the above-mentioned length direction or the above-mentioned width direction. In addition, the directional words such as "upper", "lower", "top", and "bottom" described in this application are all understood relative to the vertical direction.

[0066] Herein, unless otherwise specified, "room temperature" refers to 25°C ± 3°C.

[0067] In a battery pack with a CTP structure, when the battery cell coated with an insulating film is connected to the casing through structural adhesive, the bonding strength between the insulating film on the outer surface of the battery cell and the structural adhesive is low and cannot meet the strength requirements. In order to improve the bonding strength between the battery cell and the casing, a window design is usually performed on the insulating film at the bottom of the battery cell, that is, a portion of the bottom area of ​​the battery cell is exposed so that the outer shell of the exposed battery cell contacts the structural adhesive, and the outer shell of the battery cell is bonded to the casing through the structural adhesive, thereby improving the bonding strength between the battery cell and the casing. However, the window design of the insulating film not only increases the preparation process, but also the effective contact area between the structural adhesive and the battery cell casing is small, resulting in insufficient bonding strength between the two, and further resulting in insufficient bonding strength of the battery cell in the casing.

[0068] In order to solve the above problems, the present application designs a battery pack, including a box body, a battery cell, an insulating film, and a first adhesive layer located between the first insulating film and the inner wall of the box body. The first insulating film of the battery pack at least covers the bottom surface of the battery cell, increasing the effective bonding area between the first insulating film and the structural adhesive. Without the need for a window design on the first insulating film, the first insulating film and the first adhesive layer can still have a high bonding strength, thereby improving the strength and reliability of the battery cell in the battery pack.

[0069] battery pack

[0070] Referring to Figures 1 and 2, an embodiment of the present application provides a battery pack 1, which includes:

[0071] The box body 2 has a receiving cavity 24;

[0072] The battery cell 3 is located in the accommodating cavity 24;

[0073] A first insulating film 9 is bonded to the outer surface of the battery cell 3, and the first insulating film 9 at least covers the bottom surface of the battery cell 3; and

[0074] The first adhesive layer 8 is located between the first insulating film 9 and the inner wall of the accommodating cavity 24 .

[0075] In this embodiment, the first insulating film 9 at least covers the bottom surface of the battery cell 3, increasing the effective bonding area between the first insulating film 9 and the structural adhesive. This ensures a high bonding strength between the first insulating film 9 and the first adhesive layer 8, without requiring a window design in the first insulating film 9. This improves the strength and reliability of the battery cell 3 in the casing 2. It should be understood that "the bottom surface of the battery cell 3" refers to the side away from the electrode terminals of the battery cell 3, and "the first insulating film 9 at least covers the bottom surface of the battery cell 3" means that the first insulating film 9 at least completely covers the bottom surface of the battery cell 3. The inner wall of the accommodating cavity 24 is also the inner wall of the casing 2. In the casing 2, there are multiple battery cells 3, and the multiple battery cells 3 can be arranged along the X direction. In all figures of this application, the direction indicated by arrow X is the direction in which the multiple battery cells 3 are arranged sequentially, the direction indicated by arrow Z is perpendicular to the bottom surface of the battery cell 3 covered by the first insulating film 9, and the direction indicated by arrow Y is perpendicular to the plane formed by the X and Z directions. Of course, the battery cells 3 can also be arranged in any other manner.

[0076] The present application has no particular limitation on the shape of the battery cell, which can be cylindrical, square, or any other shape. For example, FIG3 shows a battery cell 3 with a square structure as an example.

[0077] It should be noted that the battery cell 3 is also called a single cell, which can be a secondary battery. Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the battery charge and discharge process, active ions are embedded and extracted back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0078] In some embodiments, the first insulating film 9 includes unsaturated polyester.

[0079] The first insulating film 9 comprises unsaturated polyester, thereby improving the bonding strength between the first insulating film 9 and the battery cell 3 and further improving the bonding strength between the first insulating film 9 and the first adhesive layer 8 without providing a window design to the first insulating film 9 .

[0080] In some embodiments, the unsaturated polyester includes one or more of rosin-modified unsaturated polyester, para-terephthalic unsaturated polyester, bisphenol A unsaturated polyester, and vinyl unsaturated polyester.

[0081] In some optional embodiments, the first insulating film 9 can be a pure adhesive film or an adhesive film with a substrate. Specifically, the material of the substrate includes polyester. Further, the polyester can include one or more of polyethylene terephthalate (PET) and polycarbonate (PC).

[0082] In some embodiments, at room temperature, the interfacial bonding strength of the first insulating film 9 is ≥7MPa. The interfacial bonding strength of the first insulating film 9 ≥7MPa means that the interfacial bonding strength between the first insulating film 9 and other layers is ≥7MPa. In this article, at room temperature, the interfacial bonding strength of the first insulating film 9 ≥7MPa means that the interfacial bonding strength between the first insulating film 9 and the battery cell 3, and the interfacial bonding strength between the first insulating film 9 and the first adhesive layer 8 are both ≥7MPa. The following is similar. As a result, the bonding strength between the first insulating film 9 and the battery cell 3, and the bonding strength between the first insulating film 9 and the first adhesive layer 8 at room temperature are further improved. In addition, in traditional battery packs, the bonding strength between the insulating film and the battery cell is relatively small, and it is usually necessary to provide an insulating layer on the inner wall of the box to ensure that the battery cell is insulated from the box. Exemplarily, the above-mentioned insulating layer can be an insulating coating or an insulating electrophoretic layer. In this embodiment, the first insulating film 9 has a high room temperature interface bonding strength, and the inner wall of the box body 2 does not need to be provided with an insulating layer and can still ensure that the battery cell 3 and the box body 2 are insulated, thereby saving production processes and optimizing the structure of the battery pack 1.

[0083] In some embodiments, at 60°C, the interfacial bonding strength of the first insulating film 9 is ≥4MPa. As a result, the bonding strength between the first insulating film 9 and the battery cell 3 at 60°C, as well as the bonding strength between the first insulating film 9 and the first adhesive layer 8, is further improved. Normally, the normal operating temperature of the battery cell 3 does not exceed 60°C, for example, it can be -30°C to 60°C. Within the normal operating temperature range of the battery cell 3, the first insulating film 9 can maintain a relatively high interfacial bonding strength. In addition, in traditional battery packs, the bonding strength between the insulating film and the battery cell is relatively low, and an insulating layer is usually required on the inner wall of the box to ensure insulation between the battery cell and the box. For example, the insulating layer can be an insulating coating or an insulating electrophoretic layer. In this embodiment, the first insulating film 9 still has a relatively high interfacial bonding strength at 60°C, and the inner wall of the box 2 does not need to be provided with an insulating layer to still ensure insulation between the battery cell 3 and the box 2, thereby optimizing the structure of the battery pack 1, saving the production process of the battery pack 1, reducing production costs, and improving production efficiency.

[0084] In some embodiments, at 80°C, the interfacial bonding strength of the first insulating film 9 is ≤0.3 MPa. Under these temperature conditions, the bonding strength between the first insulating film 9 and the battery cell 3, as well as the bonding strength between the first insulating film 9 and the first adhesive layer 8, is relatively low. Thus, the battery pack 1 can be heated to raise the temperature of the first insulating film 9, thereby disassembling the battery cell 3, first insulating film 9, and first adhesive layer 8 in the battery pack 1. This reduces the likelihood of the first insulating film 9 and first adhesive layer 8 remaining on the outer surface of the battery cell 3, thereby improving disassembly efficiency.

[0085] In some embodiments, the outer shell of the battery cell 3 can be a hard shell, such as a steel shell, an aluminum shell, or a hard plastic shell. Optionally, the outer shell of the battery cell 3 is an aluminum shell. This further improves the bonding strength between the battery cell 3 and the first insulating film 9.

[0086] In some embodiments, the tensile elastic modulus of the first insulating film 9 is ≤0.2 MPa at 80°C. The tensile elastic modulus can represent the stiffness of the first insulating film 9. At 80°C, the tensile elastic modulus of the first insulating film 9 is small, that is, the stiffness of the first insulating film 9 is small, and the first insulating film 9 is easily detached from the surface of the battery cell 3 and the surface of the first adhesive layer 8, thereby facilitating the removal of the first insulating film 9 from the battery cell 3 and the first adhesive layer 8.

[0087] In some embodiments, the dielectric strength of the first insulating film 9 is ≥ 20 kV / mm. Therefore, the first insulating film 9 has good voltage resistance.

[0088] In some embodiments, the thickness of the first insulating film 9 is 25 μm to 75 μm, and can be 30 μm to 50 μm. Although the thickness of the first insulating film 9 is relatively thin, it can still insulate the battery cell 3 .

[0089] The battery pack 1 of the present application includes but is not limited to the following embodiments:

[0090] 3 and 4 , in some embodiments, the first insulating film 9 is coated on the bottom and side surfaces of the battery cell 3, and the first insulating film 9 extends to the top surface of the battery cell 3. Specifically, the top surface of the battery cell 3 is arranged opposite to its bottom surface, and the area connecting the top and bottom surfaces of the battery cell 3 is the side surface of the battery cell 3. In this embodiment, the first insulating film 9 fully coats the bottom and side surfaces of the battery cell 3. The first insulating film 9 extends to the top surface of the battery cell 3 to achieve insulation of the bottom and side surfaces of the battery cell 3. The top patch set on the top surface of the traditional battery cell 3 can be omitted. The side plates in the traditional battery pack and the adhesive film between the side plates and the battery cell 3 can also be omitted, thereby further optimizing the structure of the battery pack 1, saving the production process of the battery pack 1, reducing production costs, and improving production efficiency.

[0091] In some embodiments, the maximum width of the first insulating film 9 on the top surface of the battery cell 3 is 3 mm to 5 mm. This maximum width should be understood as the maximum extension distance of the first insulating film 9 on the top surface of the battery cell 3. Although the maximum width is only 3 mm to 5 mm, the high bonding strength between the first insulating film 9 and the top surface of the battery cell 3 prevents the first insulating film 9 from warping on the top surface of the battery cell 3. It is understood that the maximum width includes, but is not limited to, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm.

[0092] In conjunction with Figures 3 and 5 , in other embodiments, the first insulating film 9 covers the bottom surface of the battery cell 3 and extends to the side surfaces of the battery cell 3. It can be understood that in this embodiment, the first insulating film 9 fully covers the bottom surface of the battery cell 3 and partially covers the side surfaces of the battery cell 3. The first insulating film 9 is bonded to the bottom of the battery cell 3 and the first adhesive layer 8. This increases the effective bonding area between the first insulating film 9 and the first adhesive layer 8, further improving the strength and reliability of the battery cell 3 and reducing the difficulty of removing the battery cell 3 from the first insulating film 9.

[0093] In conjunction with Figures 3 and 6 , in other embodiments, the first insulating film 9 covers the bottom surface of the battery cell 3, but does not cover the side and top surfaces of the battery cell 3. Understandably, in this embodiment, the first insulating film 9 only fully covers the bottom surface of the battery cell 3. This increases the effective bonding area between the first insulating film 9 and the first adhesive layer 8, further improving the strength and reliability of the battery cell 3 and reducing the difficulty of removing the battery cell 3 from the first insulating film 9.

[0094] In conjunction with Figures 3 and 5-6, in some specific embodiments, the battery pack 1 further includes a second insulating film 10. The second insulating film 10 covers the side surfaces of the battery cell 3 and extends to the top surface of the battery cell 3. The second insulating film 10 contacts the first insulating film 9. It can be understood that the second insulating film 10 and the first insulating film 9 together cover the battery cell 3 to provide insulation. The second insulating film 10 contacts the first insulating film 9, and the second insulating film 10 and the first insulating film 9 may abut or intersect.

[0095] In some embodiments, the maximum width of the second insulating film 10 on the top surface of the battery cell 3 is 3 mm to 5 mm. Thus, the second insulating film 10 and the first insulating film 9 can fully cover the bottom and side surfaces of the battery cell 3, thereby achieving insulation of the bottom and side surfaces of the battery cell 3.

[0096] In some embodiments, the second insulating film 10 includes one or more of polyethylene terephthalate, polyethylene, and polycarbonate. The second insulating film 10 and the first insulating film 9 may be made of different materials. The first insulating film 9 has a higher interface bonding strength than the second insulating film 10.

[0097] In some embodiments, at room temperature, the interfacial bonding strength of the first adhesive layer 8 is ≥7 MPa. The interfacial bonding strength of the first adhesive layer 8 ≥7 MPa means that the interfacial bonding strengths between the first adhesive layer 8 and other layers are both ≥7 MPa. Herein, at room temperature, the interfacial bonding strength of the first adhesive layer 8 ≥7 MPa means that the interfacial bonding strengths between the first adhesive layer 8 and the first insulating film 9, and the interfacial bonding strengths between the first adhesive layer 8 and the inner wall of the casing 2 are both ≥7 MPa. Setting the interfacial bonding strength of the first adhesive layer 8 to the above value at room temperature improves the strength and reliability between the battery cell 3 and the inner wall of the casing 2.

[0098] In some optional embodiments, other structural parts are further provided between the first adhesive layer 8 and the inner wall of the box body 2. In this case, the bonding interface of the first adhesive layer 8 refers to the interface where the first adhesive layer 8 contacts the first insulating film 9, and the interface where the first adhesive layer 8 contacts other structural parts. The interfacial bonding strength of the first adhesive layer 8 ≥7MPa should be understood as the interfacial bonding strength between the first adhesive layer 8 and the first insulating film 9, and the interfacial bonding strength between the first adhesive layer 8 and other structural parts are both ≥7MPa. The above-mentioned other structural parts may be, for example, integrated water-cooling structural parts or non-integrated water-cooling structural parts, etc., or other commonly used structural parts in this technical field, and those skilled in the art may make their selections based on specific practical needs.

[0099] In some embodiments, the first adhesive layer 8 includes a structural adhesive, which may be, for example, a polyurethane structural adhesive or a commonly used structural adhesive in the art.

[0100] In some embodiments, the structural adhesive includes one or more of a thermally conductive structural adhesive and a non-thermal conductive structural adhesive.

[0101] In some embodiments, the battery pack 1 further includes an insulating cover 5, which is located between the battery cell 3 and the sidewall of the accommodating cavity 24. The insulating cover 5 is used for secondary insulation, isolating the battery cell 3 near the sidewall of the accommodating cavity 24 from the sidewall of the accommodating cavity 24, and preventing the battery cell 3 from contacting the sidewall of the accommodating cavity 24 and causing a short circuit.

[0102] In some optional embodiments, there are multiple battery cells 3, and adjacent battery cells 3, as well as the insulating cover 5 and the battery cells 3, are bonded together by a second adhesive layer 4. Within the housing 2, the battery cells 3 may be arranged sequentially along the X direction. Of course, the multiple battery cells 3 may also be arranged in any other manner.

[0103] In some embodiments, the second adhesive layer 4 includes one or more of a pressure-sensitive adhesive and a structural adhesive. The pressure-sensitive adhesive may be, for example, an acrylic double-sided adhesive, or a commonly used pressure-sensitive adhesive in the art. The structural adhesive may be, for example, a polyurethane structural adhesive, or a commonly used structural adhesive in the art.

[0104] In some embodiments, the battery pack 1 further includes an end plate 7 , which is located on a side of the insulating cover 5 close to the side wall of the accommodating cavity 24 .

[0105] In some embodiments, the end plate 7 and the insulating cover 5 are bonded together by a third adhesive layer 6 .

[0106] In some embodiments, the third adhesive layer 6 includes one or more of a pressure-sensitive adhesive and a structural adhesive. The pressure-sensitive adhesive may be, for example, an acrylic double-sided adhesive, or a commonly used pressure-sensitive adhesive in the art. The structural adhesive may be, for example, a polyurethane structural adhesive, or a commonly used structural adhesive in the art.

[0107] Referring to Figure 2 , in some embodiments, the housing 2 includes an upper housing 21 and a lower housing 22. The upper housing 21 is positioned over the lower housing 22, and the upper and lower housings 21 and 22 cooperate to form a receiving cavity 24. Specifically, the bottom surface of the battery cell 3 can face the bottom wall 23 of the lower housing 22. This further improves the strength and reliability of the battery cell.

[0108] In some embodiments, the lower box body 22 includes a metal material. Thus, sufficient structural strength is provided to the lower box body 22. Optionally, the lower box body 22 can be an integrated water-cooling design or a non-integrated water-cooling design. Optionally, the above-mentioned metal material includes one or more of steel and aluminum alloy. The steel refers to an iron-carbon alloy with a carbon content of between 0.02% and 2.11% by mass. Specifically, the steel may include but is not limited to cold-rolled steel. The aluminum alloy may include but is not limited to 6 series aluminum alloys. The 6 series aluminum alloy refers to an aluminum alloy with magnesium and silicon as the main alloying elements and Mg2Si phase as the strengthening phase, such as: 6 series aluminum alloys with grades 6061 and 6063.

[0109] In some embodiments, the upper housing 21 comprises one or more of a metal material, a composite material, and a plastic. Composite materials are optional. For example, the upper housing 21 can be made of sheet metal. The metal material can be an aluminum alloy. The composite material can be a carbon fiber composite material (CFRP). The carbon fiber composite material can be molded using at least one of SMC, PCM, and RTM. The plastic can be one or more of polypropylene (PP) and polycarbonate (PC).

[0110] Another embodiment of the present application provides an assembly method of the battery pack 1, which includes the following steps:

[0111] The outer surface of the battery cell 3 is covered with a first insulating film 9;

[0112] The battery core 3 covered with the first insulating film 9 is bonded to the inner wall through the first adhesive layer 8 .

[0113] Compared with the traditional battery pack assembly method, the assembly method in this embodiment is simpler and more efficient.

[0114] In some embodiments, the first insulating film 9 is coated on the outer surface of the battery cell 3 by hot pressing. Thus, the first insulating film 9 can be coated on the outer surface of the battery cell 3 more simply.

[0115] In some embodiments, the hot pressing process conditions include: hot pressing temperature of 80°C to 100°C, hot pressing pressure of 0.05MPa to 0.2MPa, and hot pressing time of 2min to 6min. Traditional battery packs are provided with side panels, and the adhesive film between the side panels and the battery cells is formed by hot pressing. On the one hand, this embodiment can omit the hot pressing film or insulating coating on the side panels in traditional battery packs. On the other hand, compared with the hot pressing process conditions of the hot pressing film on the side panels, the hot pressing temperature, hot pressing pressure and hot pressing time in this embodiment are lower. In addition, the above hot pressing process conditions ensure that the interface bonding strength between the first insulating film 9 and the battery cell 3 is high, which reduces the difficulty of operation, saves time, improves production efficiency and reduces production costs. It can be understood that the hot pressing temperature can be, for example, 80°C, 85°C, 90°C, 95°C or 100°C, the hot pressing pressure can be, for example, 0.05MPa, 0.1MPa, 0.15MPa or 0.2MPa, and the hot pressing time can be, for example, 2min, 3min, 4min, 5min or 6min.

[0116] Another embodiment of the present application further provides a method for disassembling the battery pack 1, which comprises the following steps:

[0117] Heating and keeping the battery pack 1 warm;

[0118] An external force is applied to the battery pack 1 after being kept warm.

[0119] The above disassembly method has the advantages of high disassembly efficiency and no deformation of the battery cell 3. In addition, the first adhesive layer 8 and the first insulating film 9 will not remain on the battery cell 3. There is no need to clean the residue on the battery cell 3, and the battery cell 3 can be reused.

[0120] In some embodiments, the heating temperature is 70° C. to 100° C., and the holding time is ≥ 15 minutes, thereby further improving the disassembly efficiency of the battery pack 1 .

[0121] In some optional embodiments, the heating temperature is 80° C. to 100° C., and the holding time is ≥ 15 minutes, thereby further improving the disassembly efficiency of the battery pack 1 .

[0122] In some embodiments, the direction of applying the external force is perpendicular to the bottom surface of the battery cell 3. The direction perpendicular to the bottom surface of the battery cell 3 is the Z direction. By applying the external force in the Z direction, the battery cell 3 can be quickly disassembled without deforming the battery cell 3, thereby achieving a secondary use of the battery cell 3 and further improving the disassembly efficiency of the battery pack 1.

[0123] Another embodiment of the present application further provides an electrical device, which includes the above-mentioned battery pack 1.

[0124] The battery pack 1 can be used as a power source or energy storage unit for the aforementioned electrical devices. These devices may include, but are not limited to, mobile devices, electric vehicles, electric trains, ships, satellites, and energy storage systems. Examples of mobile devices include, but are not limited to, mobile phones and laptops; and examples of electric vehicles include, but are not limited to, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, and electric trucks.

[0125] Fig. 7 shows an example of an electric device 11. The electric device 11 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0126] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0127] Example 1

[0128] The battery pack in this embodiment includes an upper case, a lower case, a battery cell, a first insulating film, and a first adhesive layer. The battery cell is located in a receiving cavity formed by the upper and lower cases. The first insulating film fully covers the bottom and side surfaces of the battery cell and extends to the top surface of the battery cell. The battery cell is bonded to the bottom wall of the lower case. The first adhesive layer is in contact with the first insulating film and the bottom wall of the lower case. Adjacent battery cells are bonded by a second adhesive layer, which is in contact with the first insulating film.

[0129] Among them, the first insulating film is a film layer formed by rosin-modified unsaturated polyester (manufacturer: ExxonMobil, model: K-950). The thickness of the first insulating film is 50μm. The first insulating film is bonded to the outer surface of the battery cell by hot pressing. The hot pressing process conditions include: hot pressing pressure 0.1MPa, hot pressing temperature 90℃, and holding time 3min; the first adhesive layer uses polyurethane structural adhesive, and the second adhesive layer uses acrylic double-sided adhesive. The outer shell of the battery cell is an aluminum shell, and the lower box is made of aluminum alloy.

[0130] Example 2

[0131] The method is basically the same as that of Example 1, except that the first insulating film is a film layer formed of para-terephthalic unsaturated polyester (manufacturer: Yanglin New Materials Co., Ltd., model: Swancor 963).

[0132] Example 3

[0133] Basically the same as Example 1, except that the thickness of the first insulating film is 25 μm.

[0134] Example 4

[0135] Basically the same as Example 1, except that the thickness of the first insulating film is 75 μm.

[0136] Comparative Example 1

[0137] The battery pack in this comparative example has a substantially identical structure to that of Example 1, except that the first insulating film does not cover the bottom surface of the battery cell; the battery cell is bonded to the bottom wall of the lower case; the first adhesive layer contacts the battery cell and the bottom wall of the lower case; adjacent battery cells are bonded by a second adhesive layer, which contacts the first insulating film;

[0138] The first insulating film is composed of a PET layer and a pressure-sensitive acrylate adhesive layer. The thickness of the PET layer and the pressure-sensitive acrylate adhesive layer are both 50 μm. The PET layer is bonded to the outer surface of the battery cell through the pressure-sensitive acrylate adhesive layer.

[0139] Performance Testing

[0140] (1) Test method for glass transition temperature (Tg): The Tg value of the first insulating film of each embodiment and comparative example, and the Tg value of the first adhesive layer and the second adhesive layer of Example 1 were obtained by DSC differential scanning calorimetry. During the test, the temperature was increased from 25°C to 100°C at a heating rate of 10°C / min.

[0141] (2) Test method for tensile elastic modulus: The tensile elastic modulus of the first insulating film of each embodiment and comparative example at different temperatures, and the tensile elastic modulus of the first adhesive layer and the second adhesive layer of Example 1 were obtained by testing using an ISO 6721-4:2019 DMA dynamic mechanical analyzer. The dimensions of the tested first insulating film, first adhesive layer, and second adhesive layer were all 8*4*0.05 mm, the test frequency was 0.1 Hz, the amplitude was 4 μm, and the tensile elastic modulus at different temperatures (25°C, 80°C) was collected using a fixed-frequency temperature sweep.

[0142] (3) Dielectric strength test method: Dielectric strength was tested under the conditions of a frequency of 50 Hz and a voltage rise rate of 500 V / s in accordance with GB / T1408.1.

[0143] (4) The interfacial bonding strength can be characterized by the shear strength and tensile strength between the interfaces. If both the shear strength and the tensile strength between the interfaces are ≥ B, then the interfacial bonding strength is ≥ B.

[0144] (4.1) Testing Method for Shear Strength at Different Interfaces: In accordance with GB / T 7124, the shear strength (T1) between the first insulating film and the aluminum shell of the battery cell, the shear strength (T2) between the first insulating film and the first adhesive layer, and the shear strength (T3) between the aluminum shell of the battery cell and the first adhesive layer were tested for each Example and Comparative Example. Since the pressure-sensitive acrylate adhesive layer in Comparative Example 1 is in direct contact with the aluminum shell of the battery cell, the shear strength (T1) between the first insulating film and the aluminum shell of the battery cell in Comparative Example 1 tests the shear strength between the pressure-sensitive acrylate adhesive layer and the aluminum shell of the battery cell.

[0145] Specifically, the shear specimens are bonded with adhesives, the base material of the adhesive bonding area adopts the material of the actual interface, the size of the shear specimen is 100*25mm, the size of the bonding area is 12.5*25mm, the size of the adhesive layer formed by the adhesive in the bonding area is 12.5*25*0.25mm (that is, the thickness of the adhesive layer is 0.25mm), the thickness of a single shear specimen is 1.6mm, and the test speed is 5mm / min.

[0146] Taking shear strength T1 as an example, the specific test method is: the first insulating film is bonded to a 100*25mm aluminum sheet under the conditions of hot pressing pressure of 0.1MPa, hot pressing temperature of 90℃, and holding time of 3min to form a first insulating film interface, and then the polyurethane structural adhesive is applied to an area of ​​12.5*25mm on the first insulating film interface, and then another 100*25mm aluminum sheet is overlapped on the coated polyurethane structural adhesive. After curing at room temperature for 7 days, the polyurethane structural adhesive is completely cured. Then the shear strength is tested under different temperature conditions (such as constant temperature conditions of 25℃, 60℃, 70℃, and 80℃), the test speed is 5mm / min, and the maximum force value is recorded. Shear strength = maximum force value / bonding area of ​​polyurethane structural adhesive.

[0147] (4.2) Testing Method for Tensile Strength of Different Interfaces: In accordance with GB / T 6329, the tensile strength (M1) between the first insulating film and the aluminum shell of the battery cell, the tensile strength (M2) between the first insulating film and the first adhesive layer, and the tensile strength (M3) between the aluminum shell of the battery cell and the first adhesive layer were tested for each Example and Comparative Example. Since the pressure-sensitive acrylate adhesive layer in Comparative Example 1 is in direct contact with the aluminum shell of the battery cell, the tensile strength (M1) between the first insulating film and the aluminum shell of the battery cell in Comparative Example 1 tests the tensile strength between the pressure-sensitive acrylate adhesive layer and the aluminum shell of the battery cell.

[0148] Specifically, the tensile strength of different interfaces is tested by bonding two cylindrical rods with a diameter of 15 mm together with an adhesive and then curing. The test speed is 5 mm / min. The base material of the adhesive bonding area adopts the material of the actual interface. The size of the adhesive layer formed by the adhesive in the bonding area is 15*15*1 mm (i.e., the diameter of the adhesive layer is 15 mm and the thickness is 1 mm).

[0149] Taking the tensile strength M1 as an example, the specific testing method is: hot-press bonding the first insulating film to a cylindrical rod with a diameter of 15 mm, and the bonding area is the interface area with a diameter of 15 mm on the cylindrical rod. Then, the polyurethane structural adhesive is applied to the interface area of ​​the above-mentioned cylindrical rod on the interface of the first insulating film, and then an aluminum cylindrical rod with a diameter of 15 mm is overlapped on the adhesive, and the overlap diameter is 15 mm. After curing at room temperature for 7 days, the polyurethane structural adhesive is completely cured. Then, the tensile strength is tested under different temperature conditions such as 25°C, 60°C, 70°C, and 80°C. The test speed is 5 mm / min, and the maximum force value is recorded. The tensile strength = maximum force value / bonding area of ​​the polyurethane structural adhesive.

[0150] The test results of the above-mentioned glass transition temperature, tensile elastic modulus, dielectric strength, shear strength and tensile strength are shown in Table 1-2.

[0151] Table 1

[0152] Table 2

[0153] As can be seen from Table 1-2:

[0154] The dielectric strength of the first insulating film of Examples 1-4 is higher than that of Comparative Example 1, indicating that the first insulating film of Examples 1-4 has superior voltage resistance. The Tg and tensile elastic modulus of the first insulating film of Examples 1-4 at 25°C are higher than those of the pressure-sensitive acrylate adhesive layer of Comparative Example 1. Furthermore, T1 and M1 at 25°C and 60°C are significantly higher than those of Comparative Example 1 under the corresponding conditions, indicating that the bonding strength between the first insulating film of Examples 1-4 and the aluminum shell of the battery cell is significantly higher. At 25°C, T1 and M1 of Comparative Example 1 are only approximately 2 MPa; at 60°C, T1 and M1 of Comparative Example 1 are only approximately 0.70 MPa. Therefore, when the bonding area between the first insulating film of Comparative Example 1 and the battery cell is small, the first insulating film may warp. At 25°C and 60°C, T1 and M1 of Examples 1-4 are much higher than those of Comparative Example 1 under the corresponding conditions, and the first insulating film of Examples 1-4 will not warp when bonded to the battery cell.

[0155] Under the conditions of 25°C and 60°C, T2 and M2 of Examples 1-4 are higher than T3 and M3 of the corresponding Comparative Example 1, indicating that the interfacial bonding strength between the first insulating film and the first adhesive layer in Examples 1-4 is high, sufficient to ensure the strength reliability between the first insulating film and the first adhesive layer, and the first insulating film in Examples 1-4 does not require the window design in Comparative Example 1, thereby optimizing the structure of the battery pack, saving the production process of the battery pack, reducing production costs, and improving production efficiency.

[0156] Battery pack disassembly

[0157] The battery packs of the embodiments and comparative examples were stored in an oven at 80° C. for 15 min and impacted three times in the Z direction with a load of 2 g and 10 ms. The interface disassembly of the battery cells in the battery packs was observed. The results are shown in Table 3.

[0158] Table 3 Disassembly results

[0159] As can be seen from Table 1-3:

[0160] The tensile modulus of the first insulating film of Examples 1-4 at 80°C was relatively low, as were T1, M1, T2, and M2. Combined with the disassembly of the battery packs of Examples 1-4 in Table 3, it can be seen that the battery cells of Examples 1-4 were not deformed, and disassembly between the battery cells and the first insulating film, and between the first insulating film and the first adhesive layer, was relatively easy. However, disassembly of the battery cell from the first adhesive layer in Comparative Example 1 was more difficult.

[0161] In summary, compared with Comparative Example 1, the first insulating film in Examples 1-4 does not require a window design, and there is excellent interface bonding strength between the battery cell and the first insulating film, and between the first insulating film and the first adhesive layer, which improves the strength and reliability of each component in the battery pack and reduces the difficulty of disassembling the battery pack. The battery cell is very easy to disassemble, the battery cell is not deformed, and can be reused.

[0162] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0163] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A battery pack, comprising: A box body having a containing cavity; A battery cell, located in the accommodating cavity; A first insulating film is bonded to the outer surface of the battery cell, and the first insulating film at least covers the bottom surface of the battery cell; and The first adhesive layer is located between the first insulating film and the inner wall of the accommodating cavity.

2. The battery pack according to claim 1, wherein: The first insulating film comprises unsaturated polyester; Optionally, the unsaturated polyester includes one or more of rosin-modified unsaturated polyester, terephthalate unsaturated polyester, bisphenol A unsaturated polyester and vinyl unsaturated polyester.

3. The battery pack according to claim 1 or 2, wherein: Under room temperature conditions, the interfacial bonding strength of the first insulating film is ≥7MPa; Optionally, at 60° C., the interface bonding strength of the first insulating film is ≥4 MPa; Optionally, at 80° C., the interface bonding strength of the first insulating film is ≤0.3 MPa; Optionally, the outer shell of the battery cell is an aluminum shell.

4. The battery pack according to any one of claims 1 to 3, wherein: At 80° C., the tensile elastic modulus of the first insulating film is ≤0.2 MPa.

5. The battery pack according to any one of claims 1 to 4, wherein: The dielectric strength of the first insulating film is ≥20 kV / mm.

6. The battery pack according to claim 1 or 5, wherein: The thickness of the first insulating film is 25 μm to 75 μm, and can be optionally 30 μm to 50 μm.

7. The battery pack according to any one of claims 1 to 6, wherein: The first insulating film covers the bottom surface and the side surface of the battery cell, and the first insulating film extends to the top surface of the battery cell; Optionally, the maximum width of the first insulating film on the top surface of the battery cell is 3 mm to 5 mm.

8. The battery pack according to any one of claims 1 to 7, wherein: At room temperature, the interfacial bonding strength of the first adhesive layer is ≥7MPa; Optionally, the first adhesive layer includes structural adhesive; more optionally, the structural adhesive includes one or more of thermally conductive structural adhesive and non-thermally conductive structural adhesive.

9. The battery pack according to any one of claims 1 to 8, wherein: The battery pack further comprises an insulating cover, wherein the insulating cover is located between the battery cell and the side wall of the accommodating cavity; Optionally, there are multiple battery cells, and adjacent battery cells, as well as the insulating cover and the battery cells, are bonded together by a second adhesive layer; Optionally, the second adhesive layer includes one or more of a pressure-sensitive adhesive and a structural adhesive.

10. The battery pack according to claim 9, wherein: The battery pack further includes an end plate, the end plate being located on a side of the insulating cover close to a side wall of the accommodating cavity; Optionally, the end plate and the insulating cover are bonded together by a third adhesive layer; Optionally, the third adhesive layer includes one or more of a pressure-sensitive adhesive and a structural adhesive.

11. The battery pack according to any one of claims 1 to 10, wherein: The box body comprises an upper box body and a lower box body, the upper box body cover is arranged on the lower box body, and the upper box body and the lower box body cooperate to form the accommodating cavity; Optionally, the lower box body includes a metal material; more optionally, the metal material includes one or more of steel and aluminum alloy.

12. The method for assembling a battery pack according to any one of claims 1 to 11, comprising the following steps: Covering the outer surface of the battery cell with the first insulating film; The battery core covered with the first insulating film is bonded to the inner wall through the first adhesive layer.

13. The assembly method according to claim 12, wherein: The first insulating film is coated on the outer surface of the battery cell by hot pressing; Optionally, the process conditions of the hot pressing include: hot pressing temperature of 80° C. to 100° C., hot pressing pressure of 0.05 MPa to 0.2 MPa, and hot pressing time of 2 min to 6 min.

14. The method for disassembling a battery pack according to any one of claims 1 to 11, comprising the following steps: Heating and keeping the battery pack warm; Apply external force to the battery pack after heat preservation.

15. The disassembly method according to claim 14, wherein: The heating temperature is 70° C. to 100° C., and the insulation time is ≥15 min.

16. The disassembly method according to claim 14 or 15, wherein: The direction of applying the external force is a direction perpendicular to the bottom surface of the battery cell.

17. An electrical device comprising the battery pack according to any one of claims 1 to 11.

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