Secondary battery and electronic device

Abstract

The invention discloses a secondary battery and an electronic device. The secondary battery comprises a packaging bag, an electrode assembly and a bonding assembly. A cavity is formed in the packaging bag, and the electrode assembly is arranged in the cavity. Along the thickness direction of the electrode assembly, the electrode assembly comprises a first surface and a second surface which are opposite. The electrode assembly has two opposite side portions in a width direction of the electrode assembly. The bonding assembly comprises two first bonding pieces, and each first bonding piece is correspondingly arranged on one side portion and partially bonded to the first face and the second face of the corresponding side portion. The side, opposite to the first face and the second face, of the first bonding piece is bonded to the inner wall of the packaging bag, and the thickness D of the secondary battery is larger than or equal to 1.5 mm and smaller than or equal to 3.2 mm. The secondary battery provided by the invention can improve the bulge problem during edge folding and forming of the packaging bag, is beneficial to reducing the thickness of the secondary battery, and improves the volume energy density of the secondary battery.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a secondary battery and an electronic device. Background Art

[0002] With the rapid development of electronic devices such as foldable screen mobile phones, the demand for ultra-thin laminated cells is increasing. When laminated cells are placed in battery packaging bags, a certain amount of space is reserved between the two opposite sides of the laminated cells in the width direction and the packaging bag. When the packaging bag is sealed and folded, it is squeezed by external force during the folding process. The space on the opposite sides of the sealing position of the packaging bag in the thickness direction of the cell is deformed, forming a bulge that exceeds the thickness of the cell body, thereby increasing the overall thickness of the cell and reducing the volume energy density of the secondary battery.

[0003] In the related art, after the battery cell is formed, it is shaped by rolling it with a rubber roller. This shaping method is beneficial to reducing the thickness of the battery cell, but there is a problem of thickness rebound after the battery cell is shaped. Summary of the invention

[0004] In view of this, it is necessary to provide a secondary battery that can improve the bulge problem during folding and forming of the packaging bag after sealing, which is beneficial to reducing the thickness of the secondary battery and improving the volume energy density of the secondary battery.

[0005] An embodiment of the first aspect of the present application provides a secondary battery, the secondary battery comprising: a packaging bag, an electrode assembly and an adhesive assembly. The packaging bag is formed with a chamber, and the electrode assembly is arranged in the chamber. Along the thickness direction of the electrode assembly, the electrode assembly includes a first surface and a second surface opposite to each other. Along the width direction of the electrode assembly, the electrode assembly has two opposite side portions. The adhesive assembly includes two first adhesive members, each of which is correspondingly arranged at one of the side portions, and partially bonded to the first surface and the second surface of the corresponding side portion; the side of the first adhesive member facing away from the first surface and the second surface is bonded to the inner wall of the packaging bag, and the thickness of the secondary battery is D, satisfying 1.5mm≤D≤3.2mm.

[0006] In the above-mentioned secondary battery, the two side portions of the electrode assembly are fixed to the inner wall of the packaging bag through an adhesive assembly, and the first adhesive member bonds the packaging bag and the electrode assembly to each other, so that the packaging bag is restricted by the first adhesive member when it is squeezed and deformed, thereby reducing the bulge in the thickness direction when the packaging bag is squeezed and deformed. The thickness D of the finished secondary battery can be limited to the range of 1.5mm≤D≤3.2mm, which improves the problem of overall thickening of the secondary battery caused by deformation of the packaging bag, improves the thickness consistency of each position, is conducive to improving the volume energy density, and improves the application of secondary batteries in the field of ultra-thin batteries.

[0007] In one or more of the above embodiments, the first adhesive member includes a first adhesive portion, a second adhesive portion and a connecting portion, the connecting portion is connected between the first adhesive portion and the second adhesive portion, the first adhesive portion is bonded between the first surface and the inner wall of the packaging bag, and the second adhesive portion is bonded between the second surface and the inner wall of the packaging bag.

[0008] In the above embodiment, the adhesive is connected as a whole by the connecting portion, which facilitates the adhesive to be pasted on the first surface and the second surface of the side at the same time, thereby improving production efficiency compared with the steps of pasting the adhesive on the first surface and the second surface separately.

[0009] In one or more of the above embodiments, along the width direction of the electrode assembly, the width of the electrode assembly is W1, and the width of the first bonding portion on the first surface is W2, satisfying 0.1W1≤W2≤0.18W1; and / or, along the width direction of the electrode assembly, the width of the second bonding portion on the second surface is W3, satisfying 0.1W1≤W3≤0.18W1.

[0010] In the above embodiment, when W2≥0.1W1, and / or W3≥0.1W1, the width of the first adhesive portion and the second adhesive portion is not easy to be too narrow, thereby ensuring the bonding stability of the first adhesive portion and the second adhesive portion on the inner wall of the packaging tape and the electrode assembly. When W2≤0.18W1, and / or W3≤0.18W1, it is beneficial to improve the problem of bulges in the packaging bag without using too much first adhesive.

[0011] In one or more of the above embodiments, along the width direction of the electrode assembly, the electrode assembly has a third surface and a fourth surface relative to each other, wherein a connecting portion of one first adhesive is bonded between the third surface and the inner wall of the packaging bag, and a connecting portion of another first adhesive is bonded between the fourth surface and the inner wall of the packaging bag.

[0012] In the above embodiment, the connecting portion can bond and fix the inner wall of the packaging bag to the third and fourth surfaces of the electrode assembly, so that when the packaging bag is folded and formed after sealing, when the two sides of the packaging bag in the width direction are squeezed, it is not easy to produce deformation bulges on both sides of the width direction of the electrode assembly under the restriction of the connecting portion, and it is not easy to increase the size of the secondary battery in the width direction, which is beneficial to reduce the loss of volume energy density of the secondary battery.

[0013] In one or more of the above embodiments, the adhesive assembly further includes a second adhesive member, which is adhered to both ends of the electrode assembly in the length direction and is wrapped around the outer circumference of the electrode assembly.

[0014] In the above embodiment, the provision of the second adhesive member is beneficial to fixing the electrode assembly, reducing the dislocation of the electrode assembly during the falling process, and improving the falling performance of the secondary battery.

[0015] In one or more of the above embodiments, the length of the electrode assembly is h1, and along the length direction of the electrode assembly, the length of the first adhesive is h2, satisfying: 0.6h1≤h2≤0.85h1.

[0016] In the above embodiment, when h2≤0.85h1, it is beneficial for the first adhesive to avoid the second adhesive at both ends of the electrode assembly in the length direction, reducing the possibility of the first adhesive and the second adhesive overlapping each other, thereby further reducing the overall thickness of the secondary battery. When h2≥0.6h1, it is beneficial to ensure that the first adhesive has a sufficient bonding area with the inner wall of the packaging bag, so that the packaging bag is not prone to deformation bulges.

[0017] In one or more of the above embodiments, 0.75h1≤h2≤0.8h1.

[0018] In the above embodiment, when 0.75h1≤h2≤0.8h1 is satisfied, the possibility of the first adhesive and the second adhesive overlapping each other is further reduced while reducing the deformation bulge of the packaging bag, and the overall thickness of the secondary battery is not easily increased.

[0019] In one or more of the above embodiments, the first adhesive member includes a first adhesive layer, a substrate layer and a second adhesive layer, the first adhesive layer is bonded to the inner wall of the packaging bag, the second adhesive layer is bonded to the electrode assembly, the first adhesive layer is a hot melt adhesive layer, and the second adhesive layer is a pressure-sensitive adhesive layer.

[0020] In the above embodiment, the first adhesive can improve the problem of the electrode assembly entering the packaging bag. Specifically, the hot melt adhesive layer is activated to have viscosity after high temperature and high pressure. This arrangement allows the first adhesive to be first bonded to the electrode assembly through the pressure-sensitive adhesive layer when assembling the secondary battery, and then the electrode assembly is placed in the packaging bag. Finally, the viscosity of the hot melt adhesive layer is activated by high temperature and high pressure to bond the hot melt adhesive layer to the packaging bag. During the process of the electrode assembly being placed in the packaging bag, the viscosity of the hot melt adhesive layer is not activated, so that the first adhesive is not easy to bond to the packaging bag during the process of the electrode assembly being placed in the packaging bag, which facilitates the placement of the electrode assembly in the packaging bag.

[0021] In one or more of the above embodiments, the adhesive assembly further includes a third adhesive member, the third adhesive member is connected between the two first adhesive members, and the third adhesive member is bonded between the inner wall of the packaging bag and the first surface or the second surface.

[0022] In the above embodiment, the provision of the third adhesive member can further improve the stability of the bonding between the electrode assembly and the packaging bag.

[0023] In one or more of the above embodiments, the first adhesive member and the third adhesive member are integrally provided.

[0024] In the above embodiment, compared with the scheme of only setting the first adhesive component, the pasting steps are reduced without increasing the thickness of the electrode assembly, and the bonding area of ​​the adhesive component to the packaging bag and the electrode assembly is increased, thereby improving the bonding stability between the electrode assembly and the packaging bag.

[0025] In one or more of the above embodiments, the packaging bag includes a first part and a second part, and the first part and the second part are connected along the thickness direction of the electrode assembly; along the thickness direction of the electrode assembly, the depth of the first part is greater than the depth of the second part, and the third adhesive is bonded between the inner wall of the first part and the first surface.

[0026] In the above embodiment, relative to the second part, the first part can cover more parts of the adhesive assembly, thereby improving the stability of the electrode assembly installed in the first part, making it difficult for the adhesive assembly to move relative to the packaging bag and the electrode assembly to shake relative to the packaging bag.

[0027] An embodiment of a second aspect of the present application provides an electronic device, comprising the secondary battery in any one of the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a three-dimensional diagram of a secondary battery in one embodiment of the present application.

[0029] Figure 2 It is a three-dimensional diagram of a packaging bag in an embodiment of the present application in an unfolded state.

[0030] Figure 3 is a schematic diagram of an electrode assembly in one embodiment of the present application.

[0031] Figure 4 is a cross-sectional view of a secondary battery in one embodiment of the present application.

[0032] Figure 5 is a top view of an electrode assembly in one embodiment of the present application.

[0033] Figure 6 is a top view of an electrode assembly in one embodiment of the present application.

[0034] Figure 7 is a cross-sectional view of a secondary battery in one embodiment of the present application.

[0035] Figure 8 It is a partial cross-sectional view of a first adhesive member in one embodiment of the present application.

[0036] Fig. 9 is a schematic diagram of an electronic device in one embodiment of the present application.

[0037] Main component symbols 1000, electronic device; 100, secondary battery; 10, electrode assembly; 101, side portion; 101a, first side portion; 101b, second side portion; 102, middle portion; 11, first pole piece; 12, second pole piece; 13, diaphragm; 14, pole ear; 141, first pole ear; 142, second pole ear; 10a, first side; 10b, second side; 10c, third side; 10d, fourth side; 20, packaging bag; 20a, first portion; 20b, second portion Two parts; 21, chamber; 22, folding area; 30, adhesive assembly; 31, first adhesive member; 311, first adhesive portion; 312, second adhesive portion; 313, connecting portion; 314, first adhesive layer; 315, substrate layer; 316, second adhesive layer; 32, second adhesive member; 321, third adhesive portion; 322, fourth adhesive portion; 33, third adhesive member; 40, protrusion; 200, device body; X, first direction; Y, second direction; Z, third direction.

[0038] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0040] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a centrally disposed element at the same time. When an element is considered to be "disposed on" another element, it may be directly disposed on the other element or there may be a centrally disposed element at the same time.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" in the specification, claims and accompanying drawings of this application are open expressions rather than closed expressions.

[0042] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0043] With the rapid development of electronic devices such as foldable screen mobile phones, the demand for ultra-thin laminated cells is increasing. When laminated cells are placed in battery packaging bags, a certain space is reserved between the two opposite sides of the laminated cells in the width direction and the packaging bag. When the packaging bag is sealed and folded, it is squeezed by external force, and the sealing position of the packaging bag is deformed toward the space on the opposite sides of the cell, forming a bulge that exceeds the thickness of the cell body, thereby increasing the overall thickness of the cell and reducing the volume energy density of the secondary battery.

[0044] In the related art, after the battery cell is formed, it is shaped by rolling it with a rubber roller. This shaping method is beneficial to reducing the thickness of the battery cell, but there is a problem of thickness rebound after the battery cell is shaped.

[0045] An embodiment of the present application provides a secondary battery and an electronic device, wherein the thickness of the secondary battery is D, satisfying 1.5 mm ≤ D ≤ 3.2 mm, and the secondary battery comprises: a packaging bag, an electrode assembly and an adhesive assembly. The packaging bag is formed with a chamber, and the electrode assembly is arranged in the chamber. Along the thickness direction of the electrode assembly, the electrode assembly comprises a first surface and a second surface. Along the width direction of the electrode assembly, the electrode assembly has two opposite side portions. The adhesive assembly comprises two first adhesive members, each of which is correspondingly arranged at one of the side portions; each first adhesive member is bonded to the first surface and the second surface of the corresponding side portion; and the side of the first adhesive member facing away from the first surface and the second surface is bonded to the inner wall of the packaging bag.

[0046] In the above-mentioned secondary battery, the two side portions of the electrode assembly are fixed to the inner wall of the packaging bag through an adhesive assembly, and the first adhesive member bonds the packaging bag and the electrode assembly to each other, so that the packaging bag is restricted by the first adhesive member when it is squeezed and deformed, thereby reducing the bulge in the thickness direction when the packaging bag is squeezed and deformed. The thickness D of the finished secondary battery can be limited to the range of 1.5mm≤D≤3.2mm, which improves the problem of overall thickening of the secondary battery caused by deformation of the packaging bag, improves the thickness consistency of each position, is conducive to improving the volume energy density, and improves the application of secondary batteries in the field of ultra-thin batteries.

[0047] The following is combined with Figures 1 to 9 , the embodiments of the present application are further described.

[0048] like Figure 1 and Figure 2 As shown, an embodiment of the present application provides a secondary battery 100 , which includes an electrode assembly 10 and a packaging bag 20 . The packaging bag 20 is formed with a chamber 21 , and the electrode assembly 10 is accommodated in the chamber 21 .

[0049] See also Figure 3The electrode assembly 10 includes a first electrode piece 11 , a second electrode piece 12 and a diaphragm 13 . The diaphragm 13 is disposed between the first electrode piece 11 and the second electrode piece 12 . The diaphragm 13 is used to isolate the first electrode piece 11 from the second electrode piece 12 .

[0050] In some embodiments, the packaging bag 20 is a flexible packaging bag 20, such as an aluminum-plastic film. In other embodiments, the packaging bag 20 is a hard shell, such as a plastic shell, or a metal shell including at least one of steel alloy, aluminum alloy, and copper alloy.

[0051] In some embodiments, the packaging bag 20 includes a first layer, a second layer, and a third layer stacked in sequence, the first layer is located at the outermost layer of the packaging bag 20, and the second layer is a metal layer.

[0052] In some embodiments, the first layer is a nylon layer.

[0053] In some embodiments, the second metal layer is an aluminum material.

[0054] In some embodiments, the third layer is a PP (Polypropylene) layer.

[0055] See also Figure 2 and Figure 4 In some embodiments, the packaging bag 20 includes a first portion 20a and a second portion 20b, and the first portion 20a and the second portion 20b are connected along the thickness direction of the electrode assembly 10. The edges of the first portion 20a and the second portion 20b overlap each other and are folded and gathered toward the electrode assembly 10 to form a folded edge region 22.

[0056] In some embodiments, the packaging bag 20 is injected with an electrolyte (not shown), and the electrolyte components include a solvent, an electrolyte salt, and an additive.

[0057] In some embodiments, the electrolyte salt includes at least one of an organic lithium salt or an inorganic lithium salt.

[0058] In some embodiments, the electrolyte salt includes but is not limited to at least one of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide LiN(CF3SO2)2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO2F)2) (LiFSI), lithium hexafluorocesium oxide (LiCsF6), lithium perchlorate (LiClO4) or lithium trifluoromethanesulfonate (LiCF3SO3).

[0059] In some embodiments, the polarities of the first electrode 11 and the second electrode 12 are different. For example, the first electrode 11 is a negative electrode, and the second electrode 12 is a positive electrode. For another example, the first electrode 11 is a positive electrode, and the second electrode 12 is a negative electrode.

[0060] In some embodiments, the first pole piece 11 includes a first current collector and a first active material layer, the first active material layer is disposed on at least one surface of the first current collector along the thickness direction of the first current collector, and the diaphragm 13 is disposed between the first pole piece 11 and the second pole piece 12. For example, the first active material layer is disposed on both surfaces of the first current collector along the thickness direction of the first current collector.

[0061] In some embodiments, the second pole piece 12 includes a second current collector and a second active material layer, and the second active material layer is disposed on at least one surface of the second current collector along the thickness direction of the second current collector. For example, the second active material layer is disposed on both surfaces of the second current collector along the thickness direction of the second current collector.

[0062] See also Figure 1 and Figure 2 In some embodiments, the electrode assembly 10 includes a pole tab 14 , and the pole tab 14 includes a first pole tab 141 and a second pole tab 142 . The first pole tab 141 is welded to the first current collector, and the second pole tab 142 is welded to the second current collector.

[0063] Taking the first electrode sheet 11 as a negative electrode sheet and the second electrode sheet 12 as a positive electrode sheet as an example, the first current collector and the second current collector may be metal layers. The first current collector may be a metal layer including at least one of copper, nickel, tantalum, titanium, etc., such as copper foil. The second current collector may be a metal layer including at least one of aluminum, nickel, tantalum, titanium, etc., such as aluminum foil.

[0064] Taking the first electrode sheet 11 as a negative electrode sheet and the second electrode sheet 12 as a positive electrode sheet as an example, the polarity of the first active material layer is negative electrode, the first active material layer includes negative electrode active materials, and the negative electrode active materials may include at least one of graphite, hard carbon, soft carbon, silicon, silicon oxygen material, silicon carbon material, etc. The polarity of the second active material layer is positive electrode, the second active material layer includes positive electrode active materials, and the positive electrode active materials may include at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese iron phosphate or lithium manganese oxide, etc.

[0065] See also Figure 3 In some embodiments, the first pole piece 11, the diaphragm 13 and the second pole piece 12 are stacked in sequence to form a stacked structure.

[0066] In some embodiments, the first pole piece 11 , the diaphragm 13 , and the second pole piece 12 are stacked and wound to form a wound structure.

[0067] See also Figure 4In some embodiments, the thickness of the secondary battery 100 is D, which satisfies 1.5 mm ≤ D ≤ 3.2 mm. The thickness of the secondary battery 100 is within this range, which is beneficial to improving the application of the secondary battery 100 in the field of ultra-thin batteries. For example, when the secondary battery 100 is applied to mobile phones, tablets and other devices, it is beneficial to further reduce the thickness of mobile phones, tablets and other devices.

[0068] In some embodiments, the length direction of the secondary battery 100 is consistent with the length direction of the electrode assembly 10, both of which are the first direction X shown in the figure; the width direction of the secondary battery 100 is consistent with the width direction of the electrode assembly 10, both of which are the second direction Y shown in the figure; the thickness direction of the secondary battery 100 is consistent with the thickness direction of the electrode assembly 10, both of which are the third direction Z shown in the figure.

[0069] In the related art of the ultra-thin secondary battery 100, the packaging bag 20 of the secondary battery 100 is relatively thin and flexible. When the edge of the packaging bag 20 is folded and deformed to form the folded edge area 22, the packaging bag 20 is squeezed by an external force, and protrusions 40 (such as Figure 4 The thickness of the secondary battery 100 is increased and the volume energy density of the secondary battery 100 is reduced.

[0070] like Figure 4 and Figure 5 As shown, in some embodiments, along the thickness direction of the electrode assembly 10, the electrode assembly 10 includes a first surface 10a and a second surface 10b. Along the width direction of the electrode assembly 10, the electrode assembly 10 has two opposite side portions 101. Specifically, the electrode assembly 10 also includes a middle portion 102, and the middle portion 102 is located between the two side portions 101. Figure 5 As shown in Figure 5 The dotted line in is used to indicate the dividing line between the two side portions 101 and the middle portion 102 .

[0071] The secondary battery 100 includes an adhesive assembly 30, and the adhesive assembly 30 includes two first adhesive members 31. Each first adhesive member 31 is correspondingly arranged on one of the side portions 101; each first adhesive member 31 is partially bonded to the first surface 10a and the second surface 10b of the corresponding side portion 101; and the side of the first adhesive member 31 facing away from the first surface 10a and the second surface 10b is bonded to the inner wall of the packaging bag 20.

[0072] The two side portions 101 of the electrode assembly 10 are fixed to the inner wall of the packaging bag 20 through the adhesive assembly 30, and the first adhesive component 31 bonds the packaging bag 20 and the electrode assembly 10 to each other, so that the packaging bag 20 is restricted by the first adhesive component 31 when it is squeezed and deformed, thereby reducing the bulge 40 generated in the thickness direction when the packaging bag 20 is squeezed and deformed. The thickness D of the finished secondary battery 100 can be limited to the range of 1.5mm≤D≤3.2mm, which improves the problem of overall thickening of the secondary battery 100 caused by deformation of the packaging bag 20, improves the thickness consistency of each position, and is beneficial to improving the volume energy density.

[0073] See also Figure 4 In some embodiments, the first adhesive member 31 includes a first adhesive portion 311, a second adhesive portion 312 and a connecting portion 313, the connecting portion 313 is connected between the first adhesive portion 311 and the second adhesive portion 312, the first adhesive portion 311 is bonded between the first surface 10a and the inner wall of the packaging bag 20, and the second adhesive portion 312 is bonded between the second surface 10b and the inner wall of the packaging bag 20.

[0074] The adhesive is connected as a whole by the connecting portion 313, so that the adhesive can be pasted on the first surface 10a and the second surface 10b of the side portion 101 at the same time. Compared with the steps of pasting the adhesive on the first surface 10a and the second surface 10b separately, the production efficiency is improved.

[0075] See also Figure 4 and Figure 5 In some embodiments, along the width direction of the electrode assembly 10, the electrode assembly 10 has a third surface 10c and a fourth surface 10d relative to each other, and the two side portions 101 of the electrode assembly 10 are respectively a first side portion 101a and a second side portion 101b, the first side portion 101a includes the third surface 10c, and the second side portion 101b includes the fourth surface 10d.

[0076] The connection portion 313 of one of the first adhesive members 31 is bonded between the third surface 10 c and the inner wall of the packaging bag 20 , and the connection portion 313 of the other first adhesive member 31 is bonded between the fourth surface 10 d and the inner wall of the packaging bag 20 .

[0077] The connecting portion 313 can bond and fix the inner wall of the packaging bag 20 to the third surface 10c and the fourth surface 10d of the electrode assembly 10, so that when the packaging bag 20 is folded and formed, when both sides of the packaging bag 20 in the width direction are squeezed, under the restriction of the connecting portion 313, it is not easy to generate deformation protrusions 40 on both sides of the width direction of the electrode assembly 10, and it is not easy to increase the size of the secondary battery 100 in the width direction, which is beneficial to reduce the loss of volume energy density of the secondary battery 100.

[0078] See also Figure 4 and Figure 5In some embodiments, along the width direction of the electrode assembly 10, the width of the electrode assembly 10 is W1, and the width of the first bonding portion 311 on the first surface 10a is W2, satisfying 0.1W1≤W2≤0.18W1; and / or, along the width direction of the electrode assembly 10, the width of the second bonding portion 312 on the second surface 10b is W3, satisfying 0.1W1≤W3≤0.18W1.

[0079] When W2≥0.1W1, or W3≥0.1W1, the width of the first adhesive portion 311 and the second adhesive portion 312 is not too narrow, thereby ensuring the bonding stability of the first adhesive portion 311 and the second adhesive portion 312 on the inner wall of the packaging tape and the electrode assembly 10. When W2≤0.18W1, or W3≤0.18W1, it is beneficial to improve the problem of bulges 40 in the packaging bag 20 without using too much first adhesive 31.

[0080] In some embodiments, the width W1 of the electrode assembly 10 is 50 mm, then: 5 mm≤W2≤9 mm, 5 mm≤W3≤9 mm.

[0081] In the winding process, the edge of the electrode assembly 10 in the width direction will form an arc region, and the width W1 of the electrode assembly 10 refers to the width of the entire electrode assembly 10, including the arc region of the electrode assembly 10. The first surface 10a and the second surface 10b also include an arc region, and the width of the first surface 10a refers to the straight-line distance from one end of the electrode assembly 10 in the width direction to the other end of the first surface 10a, and the width of the second surface 10b refers to the straight-line distance from one end of the electrode assembly 10 in the width direction to the other end of the second surface 10b.

[0082] See also Figure 6 In some embodiments, the adhesive assembly 30 further includes a second adhesive member 32 , which is bonded to both ends of the electrode assembly 10 in the length direction and is wrapped around the outer circumference of the electrode assembly 10 .

[0083] The provision of the second adhesive member 32 is beneficial to fixing the electrode assembly 10 , reducing the dislocation of the electrode assembly 10 during the falling process, and improving the falling performance of the secondary battery 100 .

[0084] See also Figure 6 In some embodiments, the tab 14 extends out from one end of the electrode assembly 10 in the length direction. The second adhesive member 32 includes a third adhesive portion 321 and a fourth adhesive portion 322. The third adhesive portion 321 is wound around and bonded to the end of the electrode assembly 10 in the length direction where the tab 14 is provided, and the fourth adhesive portion 322 is wound around and bonded to the end of the electrode assembly 10 in the length direction where the tab 14 is not provided.

[0085] See also Figure 6In some embodiments, the length of the electrode assembly 10 is h1, and the length of the first adhesive member 31 along the length direction of the electrode assembly 10 is h2, which satisfies: 0.6h1≤h2≤0.85h1. For example, the length of the electrode assembly 10 is h1 is 90 mm, then: 54 mm≤h2≤76.5 mm.

[0086] When h2≤0.85h1, it is beneficial for the first adhesive 31 to avoid the second adhesive 32 at both ends of the electrode assembly 10 in the length direction, reducing the possibility of the first adhesive 31 and the second adhesive 32 overlapping each other, thereby facilitating further reducing the overall thickness of the secondary battery 100. When h2≥0.6h1, it is beneficial to ensure that the first adhesive 31 and the inner wall of the packaging bag 20 have sufficient bonding area, thereby making it difficult for the packaging bag 20 to generate deformation bulges 40.

[0087] In some embodiments, 0.75h1≤h2≤0.8h1. For example, the length of the electrode assembly 10 is h1, which is 90 mm, then: 67.5 mm≤h2≤72 mm.

[0088] When 0.75h1≤h2≤0.8h1 is satisfied, the possibility of the first adhesive 31 and the second adhesive 32 overlapping each other is further reduced while reducing the deformation protrusion 40 of the packaging bag 20, and the overall thickness of the secondary battery 100 is not easily increased.

[0089] See also Figure 7 In some embodiments, the bonding assembly 30 further includes a third bonding member 33, the third bonding member 33 is connected between the two first bonding members 31, and the third bonding member 33 is bonded between the inner wall of the packaging bag 20 and the first surface 10a or the second surface 10b. The provision of the third bonding member 33 can further improve the bonding stability between the electrode assembly 10 and the packaging bag 20.

[0090] In some embodiments, the first adhesive member 31 and the third adhesive member 33 are integrally provided. Compared with the solution of providing only the first adhesive member 31, the pasting steps are reduced without increasing the thickness of the electrode assembly 10, and the bonding area of ​​the adhesive assembly 30 to the packaging bag 20 and the electrode assembly 10 is increased, thereby improving the bonding stability between the electrode assembly 10 and the packaging bag 20.

[0091] See also Figure 8 In some embodiments, the first adhesive member 31 includes a first adhesive layer 314, a substrate layer 315 and a second adhesive layer 316. The first adhesive layer 314 is bonded to the inner wall of the packaging bag 20, and the second adhesive layer 316 is bonded to the electrode assembly 10. The first adhesive layer 314 is a hot melt adhesive layer, and the second adhesive layer 316 is a pressure sensitive adhesive layer.

[0092] The first adhesive 31 can improve the problem of the electrode assembly 10 entering the packaging bag 20. Specifically, the hot melt adhesive layer is activated to have viscosity after high temperature and high pressure. This arrangement allows the first adhesive 31 to be firstly bonded to the electrode assembly 10 through the pressure-sensitive adhesive layer when assembling the secondary battery 100, and then the electrode assembly 10 is placed in the packaging bag 20, and finally the viscosity of the hot melt adhesive layer is activated by high temperature and high pressure, so that the hot melt adhesive layer is bonded to the packaging bag 20. During the process of the electrode assembly 10 being placed in the packaging bag 20, the viscosity of the hot melt adhesive layer is not activated, so that the first adhesive 31 and the packaging bag 20 are not easily bonded during the process of the electrode assembly 10 being placed in the packaging bag 20, which facilitates the electrode assembly 10 to be placed in the packaging bag 20.

[0093] See also Figure 4 In some embodiments, along the thickness direction of the electrode assembly 10, the depth of the first portion 20a is greater than the depth of the second portion 20b, and the third adhesive 33 is bonded between the inner wall of the first portion 20a and the first surface 10a.

[0094] Compared with the second part 20b, the first part 20a can cover more parts of the adhesive component 30, thereby improving the stability of the electrode assembly 10 installed in the first part 20a, making it difficult for the adhesive component 30 to move relative to the packaging bag 20, and the electrode assembly 10 is difficult to shake relative to the packaging bag 20.

[0095] In some embodiments, the third adhesive member 33 is made of the same material as the first adhesive member 31 .

[0096] See also Fig. 9 , an embodiment of the present application further provides an electronic device 1000, which includes the secondary battery 100 in any of the above embodiments.

[0097] In some embodiments, the electronic device 1000 may be a mobile phone, a laptop computer, a tablet computer, a drone, a power tool, an electric toy, a game console, a video recorder, a portable recorder, a radio, or a smart watch, etc., which are not listed one by one here.

[0098] In some embodiments, the electronic device 1000 further includes a device body 200, and the secondary battery 100 is installed in the device body 200. Since the electronic device 1000 adopts the technical solution of the secondary battery 100 in any of the above embodiments, it has at least the beneficial effects brought by the technical solution of any of the above embodiments of the secondary battery 100, which will not be described one by one here.

[0099] In order to verify the effect of the adhesive assembly 30 on the performance of the secondary battery 100, the following experiment was conducted: 1. Drop test: pre-treat the secondary battery 100 at 25°C, let it stand for 60 minutes at room temperature, and then test the voltage of the secondary battery 100 before the drop test; load the secondary battery 100 into a fixture, and use a drop device to drop freely from a position 1.5m from the ground (using a metal drop floor) in the following order: six faces of the secondary battery 100 and the right corner of the head, the right corner of the tail, the left corner of the head, and the left corner of the tail (angle: 45±15°), and repeat 6 rounds. After the drop, let it stand for 24 hours at room temperature, measure and record the voltage of the secondary battery 100, and check the appearance of the lithium-ion battery before and after the test and take pictures. The drop test pass judgment criteria: no smoke, no leakage, and voltage drop <50mV. 50 secondary batteries 100 were tested in each group of embodiments and comparative examples, and the number of batteries that passed the test was m, and the test pass rate was m / 50.

[0100] 2. Secondary battery 100 thickness test method: The thickness of the secondary battery 100 was measured using a flat thickness gauge (PPG) under a force of 600 g. The thickness of 50 finished secondary batteries 100 was tested for each set of embodiments and comparative examples, and the average thickness of the secondary battery 100 was taken as the thickness of the secondary battery 100 in each set of embodiments or comparative examples. The thickness gain in Table 1 refers to the thickness reduction of the secondary battery 100 in each embodiment compared with the secondary battery 100 in Comparative Example 1.

[0101] The specific settings in each embodiment and comparative example in the experiment are described in detail below.

[0102] Embodiment and comparative example: (1) Preparation of positive electrode sheet: Active materials lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), CNT (carbon nanotube), polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:0.5:0.5:1.5, N-methylpyrrolidone (NMP) is added as a solvent, and a positive electrode active material with a solid content of 75wt% is prepared, and stirred evenly for use. Aluminum foil with a thickness of 10μm is used as the positive electrode collector. The above positive electrode active material is evenly coated on one side of the positive electrode collector using a slit coater, and then dried at 90°C to obtain a positive electrode sheet coated with a positive electrode active material on one side. Then repeat the above coating steps on the other side of the positive electrode collector. Then the coated positive electrode sheet is cold pressed. Then the positive electrode ear is welded to the part of the positive electrode collector that is not covered by the positive electrode active material layer.

[0103] (2) Preparation of negative electrode sheet: Active materials artificial graphite, conductive carbon black (Super P), styrene-butadiene rubber (SBR), CMC (sodium carboxymethyl cellulose) are mixed in a weight ratio of 97:0.5:1.3:1.2, deionized water is added as a solvent, and a weight percentage of 50wt% of negative electrode active material is prepared, and the mixture is stirred evenly for use. A copper foil with a thickness of 10μm is used as a negative electrode current collector. The above negative electrode active material is evenly coated on one side of the negative electrode current collector using a slit coater, and then dried at 110°C to obtain a negative electrode sheet coated with a negative electrode active material layer on one side. Then the above steps are repeated on the other side of the negative electrode current collector to obtain a negative electrode sheet coated with a negative electrode active material layer on both sides. Then the coated negative electrode sheet is cold pressed. Thereafter, the negative electrode ear is welded to the portion of the negative electrode current collector that is not covered by the negative electrode active material layer.

[0104] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF6) was added to the basic organic solvent to dissolve and mix well to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0105] (4) Preparation of separator: A 7 μm thick polyethylene porous polymer film was used as the separator 13.

[0106] (5) Preparation of electrode assembly: The positive electrode sheet, the separator and the negative electrode sheet are stacked and wound along the thickness direction of the negative electrode sheet to obtain an electrode assembly. The length h1 of the electrode assembly is 90 mm and the width W1 is 50 mm.

[0107] (6) Preparation of bonding components: First adhesive component 31: The first adhesive layer 314 is a hot melt adhesive layer, and the second adhesive layer 316 is a pressure sensitive adhesive layer. The hot melt adhesive layer, the base material layer 315 and the pressure sensitive adhesive layer are stacked to form an adhesive component.

[0108] The second adhesive member 32 is a tape with a width of 8 mm as the third adhesive portion 321 and the fourth adhesive portion 322 . The width direction of the third adhesive portion 321 and the fourth adhesive portion 322 is consistent with the length direction of the electrode assembly 10 .

[0109] (7) Preparation of packaging bag: A single piece of packaging bag 20 material is punched and formed to form a first portion 20a and a second portion 20b. The packaging bag 20 material includes a nylon layer, an aluminum metal layer and a PP layer.

[0110] (8) Assembly of secondary battery: The third adhesive part 321 and the fourth adhesive part 322 are bonded and wrapped around the two ends of the electrode assembly 10 in the length direction, and the two first adhesive members 31 are bonded to the two side parts 101 of the electrode assembly 10; the punched packaging bag 20 is placed in the assembly fixture, with the first part 20a facing upward, and the electrode assembly 10 is placed in the first part 20a, and external force is applied to press it. Then, the second part 20b is covered on the electrode assembly 10 with the pit surface facing downward, and the three edges of the first part 20a and the second part 20b are heat-sealed by hot pressing. The unsealed edge is the side where the negative electrode ear and the positive electrode ear extend out of the packaging bag 20. Then, the electrolyte is injected through the unsealed edge, and the folded edge area 22 is formed by vacuum packaging. After standing, hot pressing, forming and other processes, the secondary battery 100 is obtained.

[0111] The difference between the secondary battery in Comparative Example 1 and the secondary battery in each embodiment is that the secondary battery in Comparative Example 1 is not provided with the first adhesive member 31 .

[0112] The experimental parameters and experimental results of each embodiment and comparative example are shown in Table 1.

[0113] Table 1 Note: 1. In each embodiment, W3=W2.

[0114] 2. “ / ” means no value.

[0115] Combining Comparative Example 1 with Examples 1 to 6, it can be seen that compared with the secondary battery 100 in Comparative Example 1 in which the first adhesive 31 is not provided, the thickness D of the secondary battery 100 in Examples 1 to 6 in which the first adhesive 31 is provided is smaller. It can be deduced that the provision of the first adhesive 31 is beneficial to improving the problem of the bulge 40 generated in the packaging bag 20.

[0116] It can be seen from the combination of Examples 1 to 6 that when 0.18W1≥W2≥0.1W1, not only can the bonding stability of the first bonding portion 311 and the second bonding portion 312 on the inner wall of the packaging bag 20 and the electrode assembly 10 be ensured, but also the problem of the bulge 40 generated in the packaging bag 20 can be improved without using too much first adhesive 31. In addition, as W2 increases, it is also beneficial to improve the drop pass rate of the secondary battery 100.

[0117] By comparing Example 1, Example 6 with Example 2 to Example 5, it can be seen that when W2≤0.1W1 or W2≥0.18W1, there is no obvious thickness gain.

[0118] It can be seen from Examples 7 to 13 that when h2≤0.6h1, the bonding firmness between the secondary battery 100 and the inner wall of the packaging bag 20 is insufficient, which may easily cause a drop failure and affect the drop pass rate. When h2≥0.85h1, the first adhesive 31 is likely to overlap with the second adhesive 32, resulting in a small thickness gain, which is not conducive to reducing the thickness of the secondary battery 100. When 0.6h1≤h2≤0.85h1 is satisfied, the possibility of the first adhesive 31 and the second adhesive 32 overlapping each other can be reduced while reducing the deformation protrusion 40 of the packaging bag 20, thereby increasing the thickness gain and not easily increasing the overall thickness of the secondary battery 100.

[0119] In addition, those skilled in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to be limiting of the present application. As long as they are within the spirit and scope of the present application, appropriate changes and modifications to the above embodiments are within the scope of the present application.

Claims

1. A secondary battery, characterized in that: The secondary battery comprises: a packaging bag, wherein the packaging bag is formed with a chamber; An electrode assembly is disposed in the chamber; along the thickness direction of the electrode assembly, the electrode assembly includes a first surface and a second surface opposite to each other; along the width direction of the electrode assembly, the electrode assembly has two opposite side portions; An adhesive assembly, the adhesive assembly comprising two first adhesive members; each of the first adhesive members is correspondingly arranged on one of the side portions, and partially bonded to the first surface and the second surface of the corresponding side portion; the side of the first adhesive member facing away from the first surface and the second surface is bonded to the inner wall of the packaging bag, and the thickness of the secondary battery is D, satisfying 1.5mm≤D≤3.2mm.

2. The secondary battery according to claim 1, wherein: The first adhesive member includes a first adhesive portion, a second adhesive portion and a connecting portion, the connecting portion is connected between the first adhesive portion and the second adhesive portion, the first adhesive portion is bonded between the first surface and the inner wall of the packaging bag, and the second adhesive portion is bonded between the second surface and the inner wall of the packaging bag.

3. The secondary battery according to claim 2, characterized in that: Along the width direction of the electrode assembly, the width of the electrode assembly is W1, the width of the first bonding portion on the first surface is W2, and 0.1W1≤W2≤0.18W1 is satisfied; And / or, along the width direction of the electrode assembly, the width of the second bonding portion on the second surface is W3, satisfying 0.1W1≤W3≤0.18W1.

4. The secondary battery according to claim 2, characterized in that: Along the width direction of the electrode assembly, the electrode assembly has a third surface and a fourth surface relative to each other, wherein the connecting portion of one of the first adhesive members is bonded between the third surface and the inner wall of the packaging bag, and the connecting portion of the other first adhesive member is bonded between the fourth surface and the inner wall of the packaging bag.

5. The secondary battery according to claim 1, wherein: The bonding assembly further includes a second bonding member, which is bonded to both ends of the electrode assembly in a length direction and is wound around the outer circumference of the electrode assembly.

6. The secondary battery according to claim 5, characterized in that: The length of the electrode assembly is h1, and along the length direction of the electrode assembly, the length of the first adhesive is h2, satisfying: 0.6h1≤h2≤0.85h1.

7. The secondary battery according to claim 6, characterized in that: 0.75h1≤h2≤0.8h1.

8. The secondary battery according to claim 1, wherein: The first adhesive component includes a first adhesive layer, a base material layer and a second adhesive layer, the first adhesive layer is bonded to the inner wall of the packaging bag, the second adhesive layer is bonded to the electrode assembly, the first adhesive layer is a hot melt adhesive layer, and the second adhesive layer is a pressure sensitive adhesive layer.

9. The secondary battery according to claim 1, wherein: The adhesive assembly further includes a third adhesive member, wherein the third adhesive member is connected between the two first adhesive members, and the third adhesive member is bonded between the inner wall of the packaging bag and the first surface or the second surface.

10. The secondary battery according to claim 9, characterized in that The first adhesive component and the third adhesive component are integrally arranged.

11. The secondary battery according to claim 9, wherein The packaging bag includes a first part and a second part, the first part and the second part are connected along the thickness direction of the electrode assembly; along the thickness direction of the electrode assembly, the depth of the first part is greater than the depth of the second part, and the third adhesive is bonded between the inner wall of the first part and the first surface.

12. An electronic device, characterized in that: Comprising the secondary battery according to any one of claims 1 to 11.

Images