Secondary battery, battery pack, and electronic device

Abstract

The present application provides a secondary battery, comprising: a housing having a side wall, an opening being formed in the side wall, and a rolling groove protruding inward being formed in a position of the side wall adjacent to the opening; the electrode assembly is contained in the shell, and the rolling groove limits movement of the electrode assembly in the central axis direction of the shell; the first current collecting disc is at least partially arranged between the electrode assembly and the rolling groove, the first current collecting disc comprises a current collecting body and a connecting piece on the periphery of the current collecting body, the current collecting body is electrically connected with the electrode assembly, and the connecting piece is connected with the shell in a welded mode to form a plurality of welding areas; a plane perpendicular to the central axis at the same height of the secondary battery intersects with the inner surface of the shell to form a ring, the ring comprises a welding area and a non-welding area, in the ring, the curvature of the welding area on the ring is C1, the curvature of the non-welding area on the ring is C2, and C1 is smaller than C2. The secondary battery provided by the utility model at least can improve the welding reliability of the first collector plate and the shell.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of secondary battery, battery pack and electronic device. BACKGROUND

[0002] In the field of new energy power battery, the application of secondary battery is more and more widely, such as secondary battery (for example, lithium ion battery) can be applied to car, energy storage, mobile phone, tablet computer, wearable device, mobile power supply, electronic cigarette, digital product, electric tool, power device, energy storage device and other electronic devices. One of the secondary battery is cylindrical battery, which includes a shell and an electrode assembly, the electrode assembly includes a positive electrode sheet, a first separator, a negative electrode sheet and a second separator, which are sequentially stacked and then wound into an electrode assembly, and then packaged in the shell. However, the existing secondary battery still needs to be further improved in some aspects. SUMMARY

[0003] In view of the problems in the related art, the purpose of the utility model is to provide a secondary battery, a battery pack and an electronic device, so as to at least solve the problem of how to increase the welding reliability of the first current collector and the shell.

[0004] To achieve the above-mentioned purpose, the embodiment of the present application provides a secondary battery, which comprises: a shell having a side wall, the side wall being formed with an opening, the side wall being provided with a roll groove protruding inward at a position adjacent to the opening; an electrode assembly accommodated in the shell, the roll groove limiting the movement of the electrode assembly in the direction of the central axis of the shell; a first current collector at least partially arranged between the electrode assembly and the roll groove, wherein the first current collector comprises a current collector body and a connecting piece at the periphery of the current collector body, the current collector body is electrically connected with the electrode assembly, the connecting piece is welded with the shell to form a plurality of welding areas, a plane perpendicular to the central axis at the same height of the secondary battery intersects with the inner surface of the shell to form an annular shape, the annular shape comprises welding areas and non-welding areas, and in the annular shape, the curvature of the welding areas on the annular shape is C1, and the curvature of the non-welding areas on the annular shape is C2, C1

[0005] In the above technical solution, in the annular shape defined by the plane at the same height of the secondary battery and the inner surface of the shell, the curvature C1 of the welding areas on the annular shape is less than the curvature C2 of the non-welding areas on the annular shape. The welding area with a smaller degree of bending than the non-welding area of the shell can at least increase the welding reliability of the first current collector and the shell, and further can reduce the occurrence of welding light leakage.

[0006] In some embodiments, any welding area forms a welding mark on the outer surface of the shell.

[0007] In some embodiments, any welding area forms a welding mark on the inner surface of the connecting piece facing the electrode assembly.

[0008] In some embodiments, the number of the welds is four groups, and the four groups of welds are equally spaced along the circumference of the shell.

[0009] In some embodiments, at the plane of the same height, the two end points of the intersection line between the outer surface of the annular weld area and the plane are R2 and R3 away from the center axis of the shell, and the straight line distance between any point between the two end points and the center axis is R1, R1 < R2 = R3.

[0010] In some embodiments, at the plane of the same height, the curvature C1 of any weld area on the annular is 0.

[0011] In some embodiments, the width direction of any weld is parallel to the center axis and perpendicular to the length direction of the weld, wherein the length of the weld is L mm, L is in the range of 4-7, and the width of the weld is W mm, W is in the range of 0.4-0.8.

[0012] In some embodiments, the side wall has a curled edge extending radially inwardly from the shell on the side of the roll groove away from the electrode assembly, and the shell extension length from the half of the width of the weld to the edge of the curled edge is B mm, B is in the range of 9.5-10.5, and the secondary battery is a cylindrical battery.

[0013] Embodiments of the present application also provide a battery pack comprising the secondary battery of any one of the above.

[0014] Embodiments of the present application also provide an electronic device comprising the secondary battery of any one of the above.

[0015] The beneficial technical effects of the present application include:

[0016] In the annular defined by the plane of the same height of the secondary battery and the inner surface of the shell, the curvature C1 of the weld area on the annular is less than the curvature C2 of the non-weld area on the annular, and the weld area with smaller curvature than the non-weld area of the shell at least increases the welding reliability of the first current collector and the shell. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0018] Figure 1 A schematic diagram of the electronic device of the embodiment of the present application is shown when the electronic device is a vehicle.

[0019] Figure 2 A perspective view of a secondary battery according to embodiments of the present application is shown.

[0020] Figure 3 A front view of a secondary battery according to embodiments of the present application is shown.

[0021] Figure 4 A partial cross-sectional view of a secondary battery after insertion of a cover plate into an opening according to embodiments of the present application is shown.

[0022] Figure 5 A schematic view of a plane at a height of a secondary battery according to embodiments of the present application and a defined annulus of a housing is shown.

[0023] Figure 6 A partial cross-sectional view of a secondary battery according to embodiments of the present application before formation of a raceway is shown. DETAILED DESCRIPTION

[0024] For a better understanding of the spirit of embodiments of the present application, reference will be made to the following portions of the present application in conjunction with embodiments thereof.

[0025] Embodiments of the present application will be described in detail below. Throughout the specification, like or similar components and components having like or similar functions are denoted by like reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative in nature, diagrammatic in nature, and are provided to give an overall understanding of the present application. The embodiments of the present application should not be construed as limiting the present application.

[0026] As used herein, the terms "approximately," "substantially," "about," and "generally" are used to describe and account for small variations. When utilized in connection with an event or circumstance, such terms can refer to instances in which the event or circumstance occurs exactly, as well as instances in which the event or circumstance occurs with a minor approximation.

[0027] In this specification, relative terms such as "central," "longitudinal," "lateral," "forward," "rearward," "rightward," "leftward," "internal," "external," "lower," "upper," "horizontal," "vertical," "above," "below," "top," "bottom," and derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the present application be constructed or operated in a particular orientation.

[0028] For ease of description, "first," "second," "third," and the like can be used herein to distinguish between different components of one figure or series of figures. "First," "second," "third," and the like are not intended to describe corresponding components.

[0029] The utility model provides a kind of electronic device 1000, and electronic device 1000 includes battery pack 1002.Electronic device 1000 is electrically connected with battery pack 1002 to obtain electric energy support.As an example, electronic device 1000 is vehicle, and vehicle can be fuel automobile, gas automobile or new energy automobile, and new energy automobile can be pure electric vehicle, hybrid vehicle or range extended vehicle, but not limited thereto.Working part is vehicle body, and battery pack 1002 is arranged at the bottom of vehicle body, and provides electric energy support for the running of vehicle or the operation of electrical element in vehicle.However, in other some embodiments, electronic device 1000 can also be mobile phone, portable device, notebook computer, ship, spacecraft, electric toy and electric tool and the like.Spacecraft includes airplane, rocket, space shuttle and spacecraft and the like;Working part can obtain the electric energy of battery pack 1002, and makes corresponding working unit component, for example, fan blade rotating unit of fan, dust absorption working unit of dust collector and the like.Electric toy includes fixed or mobile electric toy, for example, game machine, electric car toy, electric ship toy and electric plane toy and the like;Electric tool includes metal cutting electric tool, grinding electric tool, assembly electric tool and railway electric tool, for example, electric drill, electric grinder, electric wrench, electric screwdriver, electric hammer, impact drill, concrete vibrator and electric planer and the like.The above-mentioned electronic device 1000 is not specially limited in the embodiment of the application.

[0030] The following embodiments are described for convenience with electronic device 1000 as vehicle as an example.Referring to Figure 1 , the inside of vehicle is provided with battery pack 1002, and battery pack 1002 can be arranged at the bottom or head or tail of vehicle body 1001.Battery pack 1002 can be used for power supply of vehicle, for example, battery pack 1002 can be used as operating power supply of vehicle. Figure 2 A perspective view of a secondary battery 100 according to an embodiment of the application is shown.

[0031] In the secondary battery example of the utility model, the electrode assembly 120 is sealedly installed in the shell 200, along the height direction H of the secondary battery 100, the electrode assembly 120 is arranged between the end wall 111 and the rolling groove 113, and the rolling groove 113 can limit the axial movement of the electrode assembly 120 between the end wall 111 and the rolling groove 113. The electrode assembly 120 is respectively provided with a first tab and a second tab at both ends in the height direction H of the secondary battery 100, and the polarity of the first tab and the second tab is opposite, wherein the first tab faces the opening side, and the first tab is a negative tab. It should be noted that in other embodiments, the first tab can also be a positive tab, and the second tab is a negative tab.

[0032] Figure 3 A front view of the secondary battery 100 according to an embodiment of the application is shown. Figure 4 A partial sectional view of the secondary battery 100 after the cover plate 250 is inserted into the opening 122 is shown. Referring to Figure 3 And Figure 4 Preferably, the secondary battery 100 can be a cylindrical battery. The shell 200 of the secondary battery 100 can be cylindrical. The shell 200 can have a central axis 300, which is a straight line passing through the centers of the two bases of the cylinder formed by the shell 200. The shell 200 of the secondary battery 100 can have a circular ring-shaped cross section in a plane perpendicular to the central axis 300 of the shell 200, and the centers of the inner and outer circles of the circular ring are both the intersection of the central axis 300 and the cross section. At one end of the side wall 119 of the shell 200 away from the end wall 111, a rolling groove 113 protruding into the shell 200 is provided at the position adjacent to the opening 122 of the side wall 119, and the connecting piece 115 is located on the side of the rolling groove 113 facing the electrode assembly 120. It can be understood that the rolling groove 113 can be electrically connected with the plurality of connecting pieces 115 of the first current collector 124, and preferably the number of connecting pieces 115 is four. The electrode assembly 120 is accommodated in the shell 100, the rolling groove 113 limits the movement of the electrode assembly 120 on the central axis 300 of the shell, the first current collector 124 is at least partially arranged between the electrode assembly 120 and the rolling groove 113, the first current collector 124 includes a current collector body and a connecting piece 115 at the periphery of the current collector body, the current collector body is electrically connected with the electrode assembly 120, the connecting piece 115 is bent towards the central axis 300 of the shell and is welded with the surface of the rolling groove 113 facing the electrode assembly 120, and the shell 200 and the connecting piece 115 are welded to form a plurality of welding areas 117.

[0033] The electrode assembly 120 of the secondary battery 100 is mainly formed by winding the positive electrode tab and the negative electrode tab, and a first separator and a second separator are usually arranged between the positive electrode tab and the negative electrode tab. The positive electrode tab comprises a positive electrode current collector and a positive electrode active material layer coated on the surface of the positive electrode current collector; the positive electrode current collector comprises a positive electrode coating area coated with the positive electrode active material layer and a positive electrode tab not coated with the positive electrode active material layer. The negative electrode tab comprises a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector; the negative electrode current collector comprises a negative electrode coating area coated with the negative electrode active material layer and a negative electrode tab not coated with the negative electrode active material layer. Taking a lithium ion battery as an example, the material of the positive electrode current collector can be aluminum, the positive electrode active material layer comprises a positive electrode active material, and the positive electrode active material can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate, etc. The material of the negative electrode current collector can be copper, the negative electrode active material layer comprises a negative electrode active material, and the negative electrode active material can be carbon or silicon, etc. The material of the first separator and the second separator can be PP (polypropylene) or PE (polyethylene), etc. In order to protect and insulate the electrode assembly 120, an insulating film can also be wrapped outside the electrode assembly 120, and the insulating film can be synthesized by PP, PE, PET (polyethylene terephthalate), PVC (polyvinyl chloride) or other high molecular polymer materials.

[0034] Reference is made to Figure 4 As shown, the cover plate 250 is inserted into the opening 122, and the opening 122 is not closed, and the opening 122 is defined by the side wall 119 of the shell 200. The first current collecting disc 124 is arranged on the end of the electrode assembly 120 accommodated in the shell 200 and facing the opening 122, and the first current collecting disc 124 comprises a current collecting body and a connecting sheet 115 at the periphery of the current collecting body. The shell 200 is welded to the connecting sheet 115 to form a plurality of welding areas 117.

[0035] Reference is made to Figure 4 and Figure 5 At the same height of the secondary battery 100, a plane perpendicular to the central axis 300 intersects the inner surface of the shell 200 to form an annular area 117R. Figure 5 The point where the plane intersects the central axis 300 is the center point. The annular area 117R comprises the welding areas 117 and the non-welding area 2001, that is, the annular area 117R passes through the non-welding area 2001 and the welding areas 117. Figure 5Here, a welded area 117 is used as an example. The curvature of welded area 117 within ring 117R is C1, while the curvature of non-welded area 2001 within ring 117R is C2, with C1 being smaller than C2. For example, welded area 117 forms line segment 117A within ring 117R, and line segment 117A has a curvature of C1. The non-welded area forms line segment 117B within ring 117R, and line segment 117B has a curvature of C2. Line segments 117A and 117B together form a closed ring 117R.

[0036] It is understood that curvature can reflect the degree of bending. That is, if C1 is less than C2, it means that the curvature of the welded area 117 is less than that of the non-welded area 2001 of the housing. A welded area 117 with a smaller curvature than the non-welded area 2001 can at least increase the welding reliability between the first current collecting plate 124 and the housing 200, and further reduce the occurrence of welding light leakage.

[0037] As previously mentioned, the secondary battery 100 can be a cylindrical battery. The housing 200 of the secondary battery 100 can have a circular cross-section on a plane perpendicular to the housing's central axis 300. In some embodiments, the surface of the non-welding region 2001 of the housing is an arcuate surface, while the surface of the welding region 117 is a non-arc surface. This non-arc surface is less curved than the arcuate surface, for example, it can be a flat surface. This can improve the weld reliability between the first current collecting plate and the cylindrical housing of the cylindrical battery.

[0038] In some embodiments, as Figure 5 As shown, in the ring 117R, the curvature C1 of the welding area 117 on the ring 117R can be 0, that is, the line segment 117A can be a straight line segment. In this way, the welding area 117 is a flat surface, which can further optimize the welding reliability.

[0039] Preferably, the connection piece 115 of the first current collecting plate 124 and the housing 200 are welded using laser penetration welding. During a jump weld, the housing 200 remains stationary while the laser moves. In some embodiments, the housing 200 is made of materials such as copper, iron, aluminum, steel, or aluminum alloys, preferably steel (e.g., SPCC, cold-rolled steel) for its higher strength. To prevent rusting during long-term use, the housing 200 may be coated with a rust-resistant material such as nickel. The electrode assembly 120 is sealed within the housing 200.

[0040] Continue in Figure 5In FIG, the distances from the two endpoints of the line segment 117A formed by the welding area 117 to the center point are R2 and R3 respectively, that is, the straight-line distances from the two endpoints of the line segment 117A to the central axis 300 are R2 and R3 respectively, and the distance from any point between the two endpoints of the line segment 117A to the center point is R1, and R1<R2=R3. In other words, in Figure 5 In FIG, compared with the two end points of the line segment 117A, the portion between the two end points of the line segment 117A is closer to the center point, that is, the straight line distance to the axis 300 is closer. Figure 5 In the embodiment, the line segment 117B formed by the non-welding area 2001 is a circular arc line segment. In some embodiments, for example, when the outer surface of the housing is a cylindrical surface with a radius of R, R2=R3=R.

[0041] In some embodiments where line segment 117A is a straight line segment, the midpoint of line segment 117A may have the shortest distance from axis 300, and the distance between points on line segment 117A and axis 300 becomes increasingly closer from any endpoint of line segment 117A to the midpoint of line segment 117A.

[0042] Figure 6 FIG. 2 shows a partial cross-sectional view of a secondary battery 200 according to an embodiment of the present application before the rolling groove 113 is formed. Figure 6 As shown, any welding area 117 forms a welding mark 128 on the inner surface of the connecting piece 115 facing the electrode assembly 120. Figure 6 , the weld mark 128 is a rectangular plane. It can be understood that if the connecting piece 115 of the first collecting plate 124 and the shell 200 are welded from the inside to the outside of the shell 200 to form the welding area 117, then Figure 6 As shown, the weld mark 128 will appear on the inner surface of the connecting piece 115 facing the electrode assembly 120, that is, it will appear inside the shell 200; if the connecting piece 115 of the first collecting plate 124 and the shell 200 are welded from the outside to the inside of the shell 200 to form the welding area 117, the weld mark 128 will appear on the outer surface of the side wall 119 of the shell 200, that is, the weld mark 128 will appear on the outside of the shell 200. Preferably, the first collecting plate 124 and the shell 200 can be welded by penetration welding. In some embodiments, there are four groups of weld marks 128, and the four groups of weld marks 128 are spaced at equal intervals along the circumference of the shell 200. That is: when the weld mark 128 is on the outer surface of the shell 200 as shown in FIG. Figure 3 The four groups of weld marks 128 are evenly distributed along the circumference of the housing 200. When the weld marks 128 are on the inner surface of the connecting sheet 115 facing the electrode assembly 120, the four groups of weld marks 128 are evenly distributed along the circumference of the housing 200 on the four groups of adapter sheets 115. Roll grooves 113 are formed on the sidewall 119 of the housing 200 and protrude toward the interior of the housing.

[0043] The length direction of the weld 128 is perpendicular to the center axis 300 of the case 200, the width direction of the weld 128 is parallel to the center axis 300 and perpendicular to the length direction of the weld 128, the length of the weld 128 is L mm, L is in the range of 4-7, and the width of the weld 128 is W mm, W is in the range of 0.4-0.8. In some embodiments, the side wall 119 of the case 200 has a curled edge portion extending radially inwardly of the case 200 at the side of the groove 113 facing away from the electrode assembly 120. For the sake of illustration, Figure 6 The middle side wall 119 is not curled, but it can be understood that after the curled edge portion is formed, Figure 6 The edge 200A of the side wall 119 at the opening 122 is also shown, which is the edge of the curled edge portion. The case extension length from the middle of the width of the weld 128 to the edge 200A of the case 200 at the opening 122 is B mm, B is in the range of 9.5-10.5. If B is out of the above range, the formation of the groove 113 is likely to cause the case 200 to crack, resulting in liquid leakage.

[0044] Now referring to Figure 4 the case after the groove 113 is formed, and Figure 6 the case before the groove 113 is formed, it can be understood that the case extension length from the middle of the width of the weld 128 to the edge 200A of the case 200 at the opening 122 is equal before and after the formation of the groove 113, for example, also in the range of 9.5 mm to 10.5 mm. The above refers to Figure 6 the arrangement position of the weld 128 in the circumferential direction of the case, and the shape, size of the weld 128, and the case extension length from the middle of the width of the weld 128. Figure 3 The weld 128 visible on the outer surface of the case 200.

[0045] Embodiments of the present application also provide a battery pack, such as the battery pack 1002 described above, which can include the secondary battery 100 of any of the embodiments described above, and which can have the beneficial effects described above with respect to the secondary battery 100.

[0046] Embodiments of the present application also provide an electronic device, which can include the secondary battery 100 of any of the embodiments described above, and which can have the beneficial effects described above with respect to the secondary battery 100.

[0047] The above merely provides the preferred embodiments of the present application, but is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A secondary battery characterized by comprising: The secondary battery comprises: a shell having a side wall formed with an opening, the side wall being provided with a roll groove protruding inwardly at a position adjacent to the opening; an electrode assembly accommodated in the shell, the roll groove limiting movement of the electrode assembly in a direction of a central axis of the shell; and a first current collector plate at least partially provided between the electrode assembly and the roll groove, wherein the first current collector plate comprises a current collector body and a connecting tab at a peripheral edge of the current collector body, the current collector body being electrically connected to the electrode assembly, and the connecting tab being welded to the shell to form a plurality of welded areas, a plane perpendicular to the central axis at a same height of the secondary battery intersects with an inner surface of the shell to form an annular shape, the annular shape comprising the welded areas and non-welded areas, in the annular shape, a curvature of the welded areas on the annular shape is C1, and a curvature of the non-welded areas on the annular shape is C2, C1 < C2. Any of the welded areas forms a welding mark on an outer surface of the shell.

2. The secondary battery according to claim 1, characterized by Any of the welded areas forms a welding mark on an inner surface of the connecting tab facing the electrode assembly.

3. The secondary battery according to claim 1, characterized by The number of the welding marks is four groups, and the four groups of the welding marks are equally spaced apart along a circumferential direction of the shell.

4. The secondary battery according to claim 2 or 3, characterized by 5. The secondary battery of claim 1, wherein at the plane at the same height, a straight-line distance of two end points of the welded areas on the annular shape from the central axis is R2 and R3 respectively, and a straight-line distance of any point between the two end points from the central axis is R1, R1 < R2 = R3. At the plane at the same height, the curvature C1 of any of the welded areas on the annular shape is 0.

6. The secondary battery according to claim 1, characterized by 7. The secondary battery of claim 2 or 3, wherein a width direction of any of the welding marks is parallel to the central axis and perpendicular to a length direction of the welding mark, wherein a length of the welding mark is L mm, the L is in a range of 4-7, and a width of the welding mark is W mm, the W is in a range of 0.4-0.

8.

8. The secondary battery of claim 7, wherein the side wall has a curled edge extending radially inwardly of the shell at a side of the roll groove away from the electrode assembly, a shell extension length from a half of the width of the welding mark to an edge of the curled edge is B mm, the B is in a range of 9.5-10.5; and the secondary battery is a cylindrical battery. The secondary battery of any of claims 1-8.

9. A battery pack characterized by comprising: The secondary battery of any of claims 1-8.

10. An electronic device, comprising: ​

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