Secondary battery and automobile

Abstract

The application relates to the technical field of energy storage devices, in particular to a secondary battery and a car. The insulating sheet comprises a top portion and two side portions, the top portion is located between the two side portions, wherein the side portions comprise a transverse cladding portion and a longitudinal cladding portion, and the transverse cladding portion and the longitudinal cladding portion are respectively used for cladding the transverse edges and the longitudinal edges of an electrode assembly. When the electrode assembly is placed in a shell, since the edges of the electrode assembly are cladded by the insulating sheet, the edges of the electrode assembly can be prevented from directly contacting the shell, the scratches of the edges of the electrode assembly at the opening of the shell are minimized as much as possible, the conduction between the negative electrode sheet and the positive electrode sheet of the electrode assembly is prevented, and the reliability of the secondary battery is improved.

Description

[0001] This application is a divisional application based on the invention patent application with application number 201810004917.7, application date January 3, 2018, applicant CATL, entitled "Secondary Battery and Automobile". Technical Field

[0002] This application relates to the field of energy storage device technology, and in particular to a secondary battery and an automobile. Background Technology

[0003] Currently, secondary batteries, especially lithium-ion batteries, have advantages such as high energy density, high power density, many cycles, and long storage time. They are widely used in portable electronic devices such as mobile phones, digital cameras, and laptops, and have broad application prospects in electric vehicles, electric bicycles, and other electric vehicles, as well as energy storage facilities and other large and medium-sized electric equipment. Secondary batteries have become a key to solving global problems such as the energy crisis and environmental pollution.

[0004] The insulation of the positive and negative electrodes is a crucial issue to consider during the manufacturing and use of secondary batteries. Automotive batteries consist of a casing and electrode assemblies. Because the casing is made of rigid metal and has burrs from the stamping process, the opening in the casing may scratch the thin separator of the electrode assembly when it is installed. This can expose the positive and negative electrode plates, or even cause them to overlap with the casing, resulting in a short circuit. Furthermore, the tabs on the positive and negative electrodes are thin and easily deformed. If the tabs are excessively long after the electrode assembly is installed in the casing, they may also overlap with the casing, causing a short circuit. Summary of the Invention

[0005] This application provides a secondary battery and a car that can solve the above-mentioned problems.

[0006] The first aspect of this application provides a secondary battery, comprising:

[0007] case;

[0008] Electrode assembly, the electrode assembly being housed within the housing; and

[0009] An insulating sheet, which covers the outside of the electrode assembly and is housed within the housing.

[0010] The insulating sheet includes a top and two sides, with the top located between the two sides. Each side includes a lateral covering and a longitudinal covering, which respectively cover the lateral edge and the longitudinal edge of the electrode assembly.

[0011] The inner wall of the housing is a square structure, and the electrode assembly is a wound structure with a longitudinally extending arc surface. Each longitudinal covering part covers part of the arc surface and is disposed on one side of the electrode assembly along the thickness direction.

[0012] Optionally, the transverse covering portions located on the two sides are arranged opposite each other in the thickness direction and do not overlap; the longitudinal covering portions located on the two sides are arranged opposite each other in the thickness direction and do not overlap.

[0013] Optionally, the transverse covering portions located on the two sides have gaps along the thickness direction; the longitudinal covering portions located on the two sides have gaps along the thickness direction.

[0014] Optionally, the width of the lateral covering portion is smaller than the width of the longitudinal covering portion.

[0015] Optionally, the portion of the electrode assembly opposite to the longitudinal covering portion is the side surface, and the portion of the electrode assembly opposite to the transverse covering portion is the bottom surface. The ratio of the exposed portion of the side surface to the total area of ​​the side surface is the side surface ratio, and the ratio of the exposed portion of the bottom surface to the total area of ​​the bottom surface is the bottom surface ratio. The side surface ratio is less than the bottom surface ratio.

[0016] Optionally, the width of the lateral covering portion is not greater than one-seventh of the thickness of the electrode assembly.

[0017] Optionally, each of the longitudinal covering portions is disposed on one side of the starting layer of the electrode assembly along the thickness direction, wherein the starting layer is the starting end portion of the innermost ring of the electrode assembly.

[0018] Optionally, the width of the longitudinal covering portion is not greater than one-quarter of the thickness of the electrode assembly.

[0019] Optionally, it also includes adhesive tape, wherein the portion of the electrode assembly opposite to the longitudinal covering portion is a side surface, and the adhesive tape adheres to the side surface and the longitudinal covering portion to bond and fix the electrode assembly to the longitudinal covering portions located on the two sides respectively.

[0020] Optionally, it also includes an adhesive film that wraps around the side, the adhesive tape, and the insulating sheet.

[0021] Optionally, the side portion further includes a main covering portion connected to both the longitudinal covering portion and the transverse covering portion, wherein the adhesive tape extends from one of the main covering portions through the two longitudinal covering portions to the other main covering portion.

[0022] Optionally, the portion of the electrode assembly opposite to the lateral covering portion is the bottom surface, and the portion opposite to the bottom surface is the top surface, with the adhesive tape provided at least at two locations near the top surface and the bottom surface.

[0023] Optionally, in one of the sides, the edge of the lateral covering portion transitions to the edge of the longitudinal covering portion in an arc shape.

[0024] A second aspect of this application provides a vehicle including a secondary battery as described in any of the preceding claims.

[0025] The technical solution provided in this application can achieve the following beneficial effects:

[0026] The insulating sheet provided in this application has a lateral covering portion and a longitudinal covering portion. Before the electrode assembly is placed into the housing, the insulating sheet covers the electrode assembly, so that the lateral covering portion and the longitudinal covering portion cover the lateral edge and the longitudinal edge of the electrode assembly, respectively. In this way, when the electrode assembly is placed in the housing, since each edge of the electrode assembly is covered by the insulating sheet, it can prevent the edges of the electrode assembly from directly contacting the housing, thereby reducing the scraping of the edges of the electrode assembly at the opening of the housing, preventing the positive electrode plate and the negative electrode plate of the electrode assembly from conducting, and improving the safety of the secondary battery.

[0027] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0028] Figure 1 A schematic diagram of the structure of a secondary battery according to a specific embodiment of this application;

[0029] Figure 2 An exploded view of a secondary battery according to a specific embodiment provided in this application;

[0030] Figure 3 A cross-sectional view of an embodiment of this application after an insulating sheet covers two electrode assemblies and is installed in a housing;

[0031] Figure 4 for Figure 3 A magnified view of a portion of point I in the middle;

[0032] Figure 5 A plan view of an insulating sheet after unfolding according to a specific embodiment provided in this application;

[0033] Figure 6 An isometric view from a rear view of an embodiment of the insulating sheet covering two electrode assemblies provided in this application;

[0034] Figure 7A front view of an embodiment of this application showing an insulating sheet covering two electrode assemblies;

[0035] Figure 8 A side view of an embodiment of this application showing an insulating sheet covering two electrode assemblies;

[0036] Figure 9 An isometric view from another perspective of an insulating sheet covering two electrode assemblies according to a specific embodiment provided in this application;

[0037] Figure 10 A cross-sectional view of an electrode assembly in a specific embodiment of the secondary battery provided in this application.

[0038] Figure label:

[0039] 10 - Shell;

[0040] 11-Cavity;

[0041] 20 - Electrode assembly;

[0042] 21-Transverse edge;

[0043] 22-Longitudinal edge;

[0044] 23-Main surface;

[0045] 24-Side view;

[0046] 241 - Top;

[0047] 25-Top surface;

[0048] 26-Bottom;

[0049] 27-First electrode;

[0050] 271 - Initial Layer;

[0051] 28 - Second pole piece;

[0052] 29-Diaphragm;

[0053] 30 - Insulating sheet;

[0054] 31 - Top;

[0055] 311 - Hollowed-out area;

[0056] 32-Side;

[0057] 321 - Lateral covering part;

[0058] 322 - Longitudinal covering portion;

[0059] 323 - Horizontal crease;

[0060] 324 - Vertical crease;

[0061] 325 - Top crease;

[0062] 326 - Main covering part;

[0063] 40 - Top cover;

[0064] 50 - Adhesive tape.

[0065] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0066] The present application will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0067] by Figure 6 The placement of the secondary battery shown is the object, with the height direction of the secondary battery as the height direction Z, the length direction of the secondary battery as the length direction X, and the thickness direction of the secondary battery as the thickness direction Y.

[0068] like Figure 1-9 As shown, this application embodiment provides a secondary battery, including a housing 10, a top cover 40, an electrode assembly 20, and an insulating sheet 30. The electrode assembly 20 is housed within the housing 10; the insulating sheet 30 covers the outside of the electrode assembly 20 and is housed within the housing 10. The top cover 40 closes the housing 10 to encapsulate the electrode assembly 20 and the insulating sheet 30 within the housing 10.

[0069] like Figure 3-9 As shown, the insulating sheet 30 includes a top 31 and two sides 32. The top 31 is located between the two sides 32. The side 32 includes a transverse covering part 321 and a longitudinal covering part 322. The transverse covering part 321 and the longitudinal covering part 322 are used to cover the transverse edge 21 and the longitudinal edge 22 of the electrode assembly 20, respectively. That is, when the insulating sheet 30 wraps the electrode assembly 20, the transverse covering part 321 covers the transverse edge 21 and the longitudinal covering part 322 covers the longitudinal edge 22.

[0070] The aforementioned insulating sheet 30 is provided with a transverse covering portion 321 and a longitudinal covering portion 322. First, the insulating sheet 30 is fixed to one side of the top cover 40, and then the insulating sheet 30 is bent so that it covers the electrode assembly 20. The transverse covering portion 321 covers the transverse edge 21 of the electrode assembly 20, and the longitudinal covering portion 322 covers the longitudinal edge 22 of the electrode assembly 20. In this way, when the electrode assembly 20 is placed inside the housing 10, since each edge of the electrode assembly 20 is covered by the insulating sheet 30, it can prevent each edge of the electrode assembly 20 from directly contacting the housing 10, thereby minimizing the scraping of each edge of the electrode assembly 20 at the opening of the housing 10, preventing the positive electrode plate and the negative electrode plate of the electrode assembly 20 from conducting, and improving the safety of the secondary battery.

[0071] In this design, the edge extending along the height direction Z of the electrode assembly 20 is the longitudinal edge 22, and the edge extending along the length direction X is the transverse edge 21. (Refer to...) Figure 2 The electrode assembly 20 includes two main surfaces 23 arranged opposite each other along the thickness direction Y, a side surface 24 connecting the two main surfaces 23, a top surface 25 connecting the main surfaces 23 and the side surface 24, and a bottom surface 26 arranged opposite to the top surface 25 along the height direction Z. A transverse edge 21 is formed at the intersection of the main surfaces 23 and the bottom surface 26, and a longitudinal edge 22 is formed at the intersection of the main surfaces 23 and the side surface 24. Accordingly, after the insulating sheet 30 wraps around the electrode assembly 20, as... Figure 3-9 As shown, the side surface 24 of the electrode assembly 20 is opposite to the longitudinal covering portion 322, and the bottom surface 26 of the electrode assembly 20 is opposite to the transverse covering portion 321. That is, the transverse covering portion 321 of the insulating sheet 30 is arranged along the length direction X, and the longitudinal covering portion 322 is arranged along the height direction Z.

[0072] Electrode assembly 20 can be provided as one or multiple, such as Figure 9 As shown, there are two electrode assemblies 20. At this time, the insulating sheet 30 simultaneously wraps the two electrode assemblies 20. The longitudinal covering part 322 wraps the outermost longitudinal edge 22 of the two electrode assemblies 20, and the transverse covering part 321 wraps the outermost transverse edge 21 of the two electrode assemblies 20.

[0073] Understandably, the insulating sheet 30 has an unfolded state and a wrapped state, as shown in the reference. Figure 5 The diagram shown is a structural schematic of the insulating sheet 30 in its unfolded state. Figure 6-9 This is a schematic diagram of the insulating sheet 30 in the wrapped state. The side 32 is bent along the transverse crease 323 to form the transverse covering part 321, and bent along the longitudinal crease 324 to form the longitudinal covering part 322.

[0074] Optionally, the top 31 is connected to the two sides 32, and the insulating sheet 30 has an approximately rectangular structure when unfolded, such as... Figure 5As shown, with this structure, the substrate can be directly cut along two directions to form each insulating sheet 30, without the need to cut the notches. The relatively irregular structure is easy to manufacture and reduces production costs.

[0075] When the insulating sheet 30 wraps the electrode assembly 20, the top 31 wraps the top surface 25 of the electrode assembly 20, that is, it is located between the top cover 40 and the electrode assembly 20. When the insulating sheet 30 wraps the electrode assembly 20, the side portion 32 can be bent along the top crease 325 to wrap the main body surface 23 of the electrode assembly 20. That is, the side portion 32 also includes a main covering portion 326. The main covering portion 326 connects the longitudinal covering portion 322 and the transverse covering portion 321. The main covering portion 326 wraps the main body surface 23 of the electrode assembly 20.

[0076] It should be noted that a hollow area 311 is provided on the top 31, such as... Figure 5 As shown, this corresponds to the injection hole, explosion-proof valve hole, and through hole for setting the pole on the top cover 40.

[0077] Each side portion 32 is provided with two longitudinal covering portions 322 to cover each of the transverse edges 21 and longitudinal edges 22 of the electrode assembly 20.

[0078] In one embodiment, when the insulating sheet 30 wraps the electrode assembly 20, along the thickness direction Y, the two longitudinal covering portions 322 have overlapping areas, and the two transverse covering portions 321 have overlapping areas; that is, the two longitudinal covering portions 322 on the same side are stacked, and the two transverse covering portions 321 are stacked. In this way, the overall structure formed after the insulating sheet 30 wraps the electrode assembly 20 increases the thickness of the electrode assembly 20 by four layers along the length direction X and by two layers along the height direction Z, which reduces the energy density of the secondary battery.

[0079] In this application, the insulating sheet 30 has two transverse covering portions 321 located on the two sides 32, which are arranged opposite each other along the thickness direction Y and do not overlap. Figure 3 As shown; the longitudinal covering portions 322 located on the two sides 32 are arranged opposite each other along the thickness direction Y and do not overlap, as... Figure 8 As shown. That is, the two transverse covering portions 321 do not overlap each other, and the two longitudinal covering portions 322 on the same side do not overlap each other, as shown. Figure 9 As shown; and the width D1 of the transverse covering portion 321 is smaller than the width D2 of the longitudinal covering portion 322, as... Figure 5As shown, the widths mentioned above refer to the dimensions along the thickness direction Y after the secondary battery is assembled. With this arrangement, the overall structure formed after the insulating sheet 30 wraps around the electrode assembly 20 only requires two layers of insulating sheet 30 thickness in the length direction X and only one layer in the height direction Z of the secondary battery. Clearly, this reduces the space occupied by the insulating sheet 30 inside the secondary battery, thereby increasing the energy density of the secondary battery. Furthermore, with the two lateral covering portions 321 positioned opposite each other, after the electrode assembly 20 is installed in the housing 10, the electrolyte inside the secondary battery can pass through the gap between the two lateral covering portions 321, directly from the outside of the insulating sheet 30 and through the gap between the two lateral covering portions 321 into the electrode assembly 20. This makes it easier for the electrolyte to enter the electrode assembly 20, increasing the wettability of the positive and negative electrodes and improving the electrochemical performance of the secondary battery. This solves the problem of scratching when the electrode assembly is placed in the housing 10, while also improving the energy density and electrochemical performance of the secondary battery. Furthermore, when the electrode assembly 20 is placed into the housing 10, the transverse edge 21 enters the opening of the housing 10 first and then no longer contacts the opening, while the longitudinal edge 22 needs to be in constant contact with the opening during the process of placing the electrode assembly 20 into the housing 10. Therefore, the longitudinal edge 22 is easily scratched, while the transverse edge 21 is less likely to be scratched than the longitudinal edge 22. Moreover, after the longitudinal edge 22 is scratched, the resulting burrs may continuously contact the housing 10 and other components during the entire process of placing the electrode assembly 20 into the housing 10, causing varying degrees of deformation and resulting in serious damage to the electrode assembly 20, leading to unpredictable safety issues. In this application, the width D1 of the transverse covering portion 321 is set to be smaller than the width of the longitudinal covering portion 322 to ensure that the longitudinal covering portion 322 has sufficient coverage area. Even if it is touched by the opening, the longitudinal edge 22 will not be exposed, thereby ensuring the reliability of the insulating sheet 30's wrapping of the electrode assembly 20 during the entire process of placing it into the housing 10, and thus improving the safety performance of the secondary battery.

[0080] Furthermore, a gap is left between the two transverse covering portions 321 to provide a channel for the electrolyte to enter the electrode assembly 20. That is, the electrolyte can enter the electrode assembly through this gap, reducing the difficulty of contact between the electrolyte and the electrode assembly 20, so that the electrolyte can more fully wet the positive and negative electrode plates of the electrode assembly, and better improve the electrochemical performance of the secondary battery.

[0081] If the edges of the two longitudinal covering portions 322 on the same side are fitted together but do not overlap, the edge requirements of the insulating sheet 30 are relatively high, which increases the manufacturing cost of the insulating sheet 30 and the overall material used for the insulating sheet 30 is relatively large. In one embodiment of this application, a gap is left between the two longitudinal covering portions 322 on the same side, so that even if the edges of the insulating sheet 30 are not smooth, it will not cause interference between the two insulating sheets 30.

[0082] Optionally, after the insulating sheet 30 wraps around the electrode assembly 20, the insulating sheet 30 is partially exposed on the side 24 and partially exposed on the bottom surface 26. The ratio of the exposed portion of the side 24 to the total area of ​​the side 24 is called the side ratio, and the ratio of the exposed portion of the bottom surface 26 to the total area of ​​the bottom surface 26 is called the bottom ratio. The side ratio is less than the bottom ratio, meaning that the exposed portion of the side 24 is less than the total area of ​​the side 24, which can further prevent the longitudinal edge 22 from being scratched when the electrode assembly 20 is placed into the housing 10.

[0083] Among them, such as Figure 5-6 As shown, the width D1 of the lateral covering portion 321 is no greater than one-seventh of the thickness D3 of the electrode assembly 20, such as D1 = 1 / 7D3, or D1 = 1 / 8D3, or D1 = 1 / 9D3. This ensures that the electrode assembly 20 will not rub against the lateral edge 21 after the insulating sheet 30 is wrapped around it, while allowing the bottom surface 26 of the electrode assembly 20 to be exposed as much as possible to provide a sufficiently large channel for the electrolyte to enter the electrode assembly 20, thereby allowing the electrolyte to fully wet the positive and negative electrode plates and improve the electrochemical performance of the secondary battery.

[0084] Understandably, the inner wall of the housing 10 has a square structure, meaning that the inner wall of the housing 10 has a narrow side facing the side 24 of the electrode assembly 20 and a wide side facing the main covering portion 326. The two narrow sides and the two wide sides form a square structure, and the connection between the narrow side and the wide side can be a straight line or a chamfered structure. The electrode assembly 20 can be a wound structure and has a longitudinally extending arc surface. That is, the electrode assembly 20 is formed by winding, and each electrode assembly 20 forms an arc surface on its side 24, such as... Figure 3 As shown, each longitudinal covering portion 322 covers a portion of the arcuate surface of the electrode assembly 20 and is disposed on one side of the electrode assembly 20 along the thickness direction Y. Preferably, each longitudinal covering portion 322 covers a portion of the arcuate surface of the electrode assembly 20 and is disposed on one side of the starting layer of the electrode assembly 20 along the thickness direction Y. Figure 3 As shown. After the electrode assembly 20 is installed into the housing 10, a cavity 11 will be formed between the arcuate surface and the housing 10, as... Figure 3 , 4As shown, since each longitudinal covering portion 322 covers a portion of the arcuate surface of the electrode assembly 20 and is disposed on one side of the electrode assembly 20 along the thickness direction, the longitudinal covering portion 322 is located within the cavity 11, and will not occupy the space in the length direction X between the electrode assembly 20 and the narrow surface of the housing (especially the area closest to the narrow side of the housing 10 in the arcuate surface) due to the presence of the longitudinal covering portion 322. In other words, compared to the existing insulating sheet (the existing insulating sheet has two longitudinal covering portions 322 on the same side stacked), That is, at least one longitudinal covering portion 322 will extend beyond the starting layer of the electrode assembly 20 along the thickness direction Y. There is a larger gap between the arcuate surface of the electrode assembly 20 and the narrow side surface of the housing 10, allowing the electrode assembly 20 to have greater expansion space in the length direction X. This prevents the arcuate surface of the electrode assembly 20 (especially the area closest to the narrow side surface of the housing 10) from excessively compressing the narrow side surface of the housing 10 during expansion and thus avoiding a large reaction force, thereby preventing the electrode (positive or negative electrode) from breaking at the arcuate surface. The starting layer is the starting end portion of the innermost ring of the electrode assembly 20, such as... Figure 10 As shown, the electrode assembly consists of a first electrode 27, a second electrode 28, and a diaphragm 29 disposed between the first electrode 27 and the second electrode 28. The innermost ring of the electrode assembly 20 is the first electrode 27, and the starting layer 271 is the starting end portion of the first electrode 27, without tabs. It should be noted that the first electrode 27 can be a positive electrode and the second electrode 28 a negative electrode; alternatively, the first electrode 27 can be a negative electrode and the second electrode 28 a positive electrode. Preferably, the width of the longitudinal covering portion 322 is no greater than one-quarter of the thickness of the electrode assembly 20.

[0085] Understandably, along the length direction X, the top edge 241 of the arc surface is closest to the housing 10. If the longitudinal covering portion 322 extends to a position near the top edge 241, the edge of the longitudinal covering portion 322 will form a burr. When the electrode assembly 20 is placed into the housing 10, the edge of the longitudinal covering portion 322 is very prone to warping or even wrinkling, increasing the overall size of the electrode assembly 20 and the insulating sheet 30, thereby reducing the energy density of the secondary battery. To solve this problem, such as Figure 5-6 As shown, the width D2 of the two longitudinal covering portions 322 located on the same side is not greater than one-quarter of the thickness D3 of the electrode assembly 20, such as D2 = 1 / 4D3, D2 = 1 / 5D3, D2 = 1 / 6D3.

[0086] In one embodiment, such as Figure 5 As shown, in one side portion 32, the edge of the transverse covering portion 321 transitions to the edge of the longitudinal covering portion 322 in an arc shape. (Reference) Figure 9After the insulating sheet 30 wraps the electrode assembly 20, the longitudinal covering part 322 and the transverse covering part 321 form a folded structure at the bottom surface 26 of the electrode assembly 20. The edge of the transverse covering part 321 and the edge of the longitudinal covering part 322 are arc-shaped, which can reduce the folded area of ​​the two, thereby making it easier to fix the insulating sheet 30 at the bottom surface 26.

[0087] After the insulating sheet 30 wraps around the electrode assembly 20, it is in a wrapped state and tends to unfold. During the process of placing the electrode assembly 20 into the housing 10, the longitudinal covering portion 322 easily touches the housing 10, thus easily causing warping or even wrinkling of the longitudinal covering portion. In one embodiment, the secondary battery also includes adhesive tape 50, which adheres to the side surface 24 of the electrode assembly 20 and the longitudinal covering portion 322 to bond and fix the electrode assembly 20 to the longitudinal covering portions 322 located on the two side surfaces 32, such as... Figure 6 As shown, this can prevent the insulating sheet 30 from unfolding when the electrode assembly 20 is placed into the housing 10, thereby avoiding warping and wrinkling of the longitudinal covering portion 322.

[0088] Specifically, the adhesive tape 50 extends from one main covering portion 326 through two longitudinal covering portions 322 to another main covering portion 326, that is, the adhesive tape 50 bypasses one side 24 of the electrode assembly 20 to better fix the longitudinal covering portion 322 to the electrode assembly 20 and prevent the longitudinal covering portion 322 from warping and wrinkling during the process of inserting the electrode assembly 20 into the housing 10.

[0089] The adhesive tape 50 can be provided in one or multiple ways. When multiple tapes are provided, the adhesive tape 50 is provided at least at two positions: near the top surface 25 of the electrode assembly 20 and near the bottom surface 26 of the electrode assembly 20. Since the side portion 32 and the top portion 31 of the insulating sheet 30 are bent near the top surface 25, and the transverse covering portion 321 and the longitudinal covering portion 322 are folded together near the bottom surface 26, the insulating sheet 30 tends to unfold more at these two positions than at other positions. Providing the adhesive tape 50 at these positions can better fix the insulating sheet 30.

[0090] Furthermore, the secondary battery also includes an adhesive film (not shown in the figure), which wraps the side surface, adhesive tape 50, and insulating sheet 30. That is, the insulating sheet 30 is wrapped around the entire circumference of one side surface 24, one main surface 23, and the other side surface 24 to the other main surface 23 of the electrode assembly 20. At the same time, an adhesive film can also be wrapped on the bottom surface 26 side of the electrode assembly 20. In this way, the electrode assembly 20 and the insulating sheet 30 form a whole. When it is placed into the housing, the warping and wrinkling of the insulating sheet 30 can be better prevented, thereby better ensuring the integrity and safety of the electrode assembly 20.

[0091] Of course, when an adhesive film is provided on the bottom surface 26, multiple through holes can be provided on the adhesive film to provide a channel for the electrolyte to flow into the electrode assembly 20, so that the electrolyte can better wet the positive electrode and the negative electrode.

[0092] In addition, this application also provides a vehicle including a secondary battery as described in any of the above embodiments.

[0093] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A secondary battery, characterized in that, include: case; An electrode assembly, wherein the electrode assembly is housed within the housing; and An insulating sheet, which covers the outside of the electrode assembly and is housed within the housing. The insulating sheet includes a top and two sides, with the top located between the two sides. Each side includes a lateral covering and a longitudinal covering, which respectively cover the lateral edge and the longitudinal edge of the electrode assembly. The inner wall of the housing has a square structure, and the electrode assembly has a wound structure with a longitudinally extending arc surface. Each longitudinal covering part covers part of the arc surface and is disposed on one side of the electrode assembly along the thickness direction. The transverse covering portions located on the two sides are arranged opposite each other along the thickness direction and do not overlap; the longitudinal covering portions located on the two sides are arranged opposite each other along the thickness direction and do not overlap. The transverse covering portions located on the two sides have gaps along the thickness direction; the longitudinal covering portions located on the two sides have gaps along the thickness direction.

2. The secondary battery according to claim 1, characterized in that, The width of the lateral covering part is smaller than the width of the longitudinal covering part.

3. The secondary battery according to claim 1, characterized in that, The portion of the electrode assembly opposite to the longitudinal covering portion is the side surface, and the portion of the electrode assembly opposite to the transverse covering portion is the bottom surface. The ratio of the exposed portion of the side surface to the total area of ​​the side surface is the side surface ratio, and the ratio of the exposed portion of the bottom surface to the total area of ​​the bottom surface is the bottom surface ratio. The side surface ratio is less than the bottom surface ratio.

4. The secondary battery according to claim 1, characterized in that, The width of the lateral covering portion is no greater than one-seventh of the thickness of the electrode assembly.

5. The secondary battery according to any one of claims 1-4, characterized in that, Each of the longitudinal covering portions is disposed on one side of the starting layer of the electrode assembly along the thickness direction, the starting layer being the starting end portion of the innermost ring of the electrode assembly.

6. The secondary battery according to any one of claims 1-4, characterized in that, The width of the longitudinal covering portion is no greater than one-quarter of the thickness of the electrode assembly.

7. The secondary battery according to any one of claims 1-4, characterized in that, It also includes adhesive tape, wherein the portion of the electrode assembly opposite to the longitudinal covering portion is a side surface, and the adhesive tape is used to bond the side surface and the longitudinal covering portion to bond and fix the electrode assembly to the two longitudinal covering portions located on the two sides respectively.

8. The secondary battery according to claim 7, characterized in that, It also includes an adhesive film that wraps around the side, the adhesive tape, and the insulating sheet.

9. The secondary battery according to claim 7, characterized in that, The side portion also includes a main covering portion connected to both the longitudinal covering portion and the transverse covering portion, and the adhesive tape extends from one of the main covering portions through the two longitudinal covering portions to the other main covering portion.

10. The secondary battery according to claim 9, characterized in that, The portion of the electrode assembly opposite to the lateral covering portion is the bottom surface, and the portion opposite to the bottom surface is the top surface. The adhesive tape is provided at least at two locations near the top surface and the bottom surface.

11. The secondary battery according to any one of claims 1-4, characterized in that, In one of the side portions, the edge of the lateral covering portion transitions to the edge of the longitudinal covering portion in an arc shape.

12. A car, characterized in that, Includes the secondary battery as described in any one of claims 1-11.

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