Secondary battery, battery pack and electronic device

Abstract

The utility model provides a secondary battery, a battery pack and an electronic device, the secondary battery comprises a shell and an electrode assembly, the shell comprises a side wall with an opening at one end and a cover plate assembly covering the opening; the electrode assembly is arranged in the shell; the cover plate assembly comprises a first cover plate, a second cover plate and a sealing plate. The first cover plate covers the opening and comprises a through hole; the second cover plate is connected to the first cover plate and comprises a liquid injection hole and a convex part, the convex part surrounds the periphery of the liquid injection hole, and the convex part comprises an annular platform exposed from the interior of the through hole; the outer periphery of the sealing plate is lapped on the annular platform, and is welded with the first cover plate and / or the second cover plate to cover and seal the liquid injection hole; the inner periphery of the annular platform forms a step section, and the surface of the side, away from the electrode assembly, of the sealing plate is lower than the surface of the side, away from the electrode assembly, of the first cover plate. The secondary battery can improve the technical problem that the cover plate assembly of the existing secondary battery is easy to deform under the action of internal pressure to influence the installation of the secondary battery.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field, concretely relates to a secondary battery, battery pack and electronic device. BACKGROUND

[0002] The existing secondary battery is generally provided with a cover plate assembly at the open end of the shell, and the open end is sealed by the cover plate assembly. The current cover plate assembly is insufficient in strength, and is prone to deformation under the action of welding or internal pressure of the secondary battery, which affects the installation or placement of the secondary battery. Therefore, a secondary battery, battery pack and electronic device are needed to solve the above problems. SUMMARY

[0003] The utility model provides a secondary battery, battery pack and electronic device to improve the technical problem that the cover plate assembly of the existing secondary battery is prone to deformation under the action of internal pressure and affects the installation of the secondary battery.

[0004] To achieve the above object and other related objects, the utility model provides a secondary battery, which comprises a shell and an electrode assembly, the shell comprises a side wall with one end being open and a cover plate assembly covering the opening, the electrode assembly is arranged in the shell, and the cover plate assembly comprises a first cover plate, a second cover plate and a sealing plate. The first cover plate covers the opening and is sealingly connected with the side wall, the first cover plate comprises a through hole, the second cover plate is connected to one side of the first cover plate close to the electrode assembly and comprises a liquid injection hole and a protruding part formed by stamping, the protruding part surrounds the outer periphery of the liquid injection hole and protrudes to one side of the first cover plate, the protruding part comprises an annular platform exposed from the through hole, and the outer periphery of the sealing plate is lapped on the annular platform and is welded with the first cover plate and / or the second cover plate to cover the liquid injection hole; wherein the inner periphery of the annular platform is bent and extended to form a stage on one side of the electrode assembly, and the surface of the sealing plate on the side away from the electrode assembly is lower than the surface of the first cover plate on the side away from the electrode assembly.

[0005] In an embodiment of the secondary battery of the utility model, the second cover plate is welded or riveted to one side of the first cover plate close to the electrode assembly.

[0006] In an embodiment of the secondary battery of the utility model, the sealing plate and the first cover plate are connected by first welding marks, and the first welding marks are arranged between the outer periphery of the sealing plate and the side wall of the through hole.

[0007] In the secondary battery embodiment of the utility model, the sealing plate and the second cover plate are connected through the second welding mark welding, the second welding mark is arranged in the overlapping area of the sealing plate and the annular platform, the molten pool opening of the second welding mark is located on the sealing plate, and the molten pool depth of the second welding mark in the overlapping area is less than the total thickness of the second cover plate and the sealing plate at the position of the second welding mark.

[0008] In the secondary battery embodiment of the utility model, the sealing plate is disc-shaped, the annular platform is also a circular ring coaxially arranged with the sealing plate, the overlapping width of the sealing plate and the annular platform is W1, and the diameter of the sealing plate is M, wherein the value of W1 / M is between 10% and 20%.

[0009] In the secondary battery embodiment of the utility model, the second cover plate is welded to the first cover plate through the third welding mark, the molten pool opening of the third welding mark is located on the second cover plate or the first cover plate, and the molten pool depth of the third welding mark is less than the total thickness of the first cover plate and the second cover plate at the position of the third welding mark.

[0010] In the secondary battery embodiment of the utility model, the thickness of the second cover plate at the position corresponding to the third welding mark is 0.3mm to 0.8mm, and the thickness of the first cover plate is 0.3mm to 0.8mm.

[0011] In the secondary battery embodiment of the utility model, the second cover plate and the first cover plate are riveted, one of the second cover plate and the first cover plate is provided with a riveting groove, the other of the second cover plate and the first cover plate is provided with a riveting boss, the riveting boss corresponds to the riveting groove and is deformed and clamped into the riveting groove after riveting.

[0012] In the secondary battery embodiment of the utility model, the width of the riveting groove is 0.2mm to 3mm, and the depth is 0.05mm to 0.4mm.

[0013] In the secondary battery embodiment of the utility model, the side wall of the through hole close to one side of the electrode assembly is provided with a notch capable of partially containing molten metal, and the notch is one or a combination of a groove, a chamfer and a round corner.

[0014] In the secondary battery embodiment of the utility model, the notch is a groove, the width W2 of the groove ranges from 0.1mm to 2.0mm, and the depth H1 of the groove ranges from 0.1mm to 0.4mm.

[0015] In the secondary battery embodiment of the utility model, the notch is a chamfer, the width W3 of the chamfer along the radial direction is 0.1mm to 0.5mm; the height H2 along the height direction of the shell is 0.1mm to 0.5mm.

[0016] In the secondary battery embodiment of the utility model, the notch is a chamfer, the width W3 of the chamfer along the radial direction is 0.1mm to 0.5mm; the height H2 along the height direction of the shell is 0.1mm to 0.5mm.

[0017] In the secondary battery embodiment of the utility model, the through hole is circular, the sealing plate is disc-shaped, and the diameter of the sealing plate is 5mm to 20mm.

[0018] The utility model also provides a battery pack, the battery pack includes the secondary battery in any example above.

[0019] The utility model provides an electronic device, the electronic device includes the battery pack.

[0020] The utility model discloses a secondary battery's cover plate subassembly includes the first cover plate and second cover plate of split setting, and the second cover plate is connected to the first cover plate and provides the support platform for sealing plate, has increased the overall strength of cover plate subassembly.Simultaneously, the inner edge of the convex part on the second cover plate forms the stage, can increase the overall strength of the lap joint position of sealing plate, can prevent the deformation of sealing plate part.In addition, the surface of the sealing plate side away from the electrode assembly is lower than the surface of the first cover plate side away from the electrode assembly in the utility model, can reduce the contact area between secondary battery and tray in the process of installing or placing secondary battery, has improved the reliability of installation connection. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description, obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other embodiments can also be obtained according to these drawings without creating creative labor.

[0022] Figure 1 It is the overall structure sectional view of the secondary battery embodiment of the utility model;

[0023] Figure 2 It is the local enlarged view of region I in the secondary battery embodiment of the utility model; Figure 1

[0024] Figure 3 It is the local enlarged view of region I in another secondary battery embodiment of the utility model; Figure 1 ​​

[0025] Figure 4 This is an exploded view of the first cover plate and the second cover plate in one embodiment of the secondary battery of this utility model;

[0026] Figure 5 This is a top view of the first cover plate and the second cover plate combined together in one embodiment of the secondary battery of this utility model.

[0027] Figure 6 This is a partial enlarged view of one side of the center line after the first cover plate and the second cover plate are riveted together in one embodiment of the secondary battery of this utility model.

[0028] Figure 7 for Figure 6 A magnified view of the riveting location;

[0029] Figure 8 This is a cross-sectional view of the first cover plate and the second cover plate combined in one embodiment of the secondary battery of this utility model;

[0030] Figure 9 for Figure 8 A magnified view of a portion of region II;

[0031] Figure 10 This is a cross-sectional view of the first cover plate and the second cover plate combined in another embodiment of the secondary battery of this utility model;

[0032] Figure 11 for Figure 10 A magnified view of a portion of region III;

[0033] Figure 12 This is a schematic diagram of the overall structure of a battery pack according to an embodiment of the present invention;

[0034] Figure 13 This is a schematic diagram of the battery pack of this utility model installed on a vehicle.

[0035] Component designation explanation

[0036] 100, secondary battery; 110, housing; 111, side wall; 112, opening; 113, end wall; 120, electrode assembly; 121, first tab; 122, second tab; 130, cover plate assembly; 131, first cover plate; 1311, through hole; 1312, notch; 1313, riveting groove; 1314, second protrusion; 132, second cover plate; 1321, first protrusion; 1322, annular platform; 1323, stage; 1324, third protrusion; 1325, liquid injection hole; 1326, riveting boss; 133, sealing plate; 140, electrode terminal; 150a, first solder print; 150b, second solder print; 160a / 160b, third solder print; 170, current collecting member; 200, battery pack; 210, box body; 211, first box body part; 212, second box body part; 300, electronic device; 310, working part. DETAILED DESCRIPTION

[0037] The above and other advantages and effects of the present application will become readily apparent to those of ordinary skill in the art from the following description thereof, taken in conjunction with the accompanying drawings. The present application can be carried out in other specific ways than those set forth herein without departing from the spirit and essential characteristics of the present application. Embodiments disclosed in this specification are intended to be illustrative only and the true scope of the present application should be determined by reference to the appended claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The present application can be implemented using any method, apparatus, material similar or equivalent to those described in the embodiments of the present application.

[0038] When the embodiments give numerical ranges, it should be understood that, unless the present application indicates otherwise, each numerical range has two endpoints and any number between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The present application can be implemented using any method, apparatus, material similar or equivalent to those described in the embodiments of the present application.

[0039] It should be noted that the terms such as "upper", "lower", "left", "right", "middle", and "one" used in the specification are only for the convenience of clear description, and are not intended to limit the scope of the present application. Changes or adjustments of the relative relationship without substantial changes in the technical content are also considered as the scope of the present application.

[0040] Please refer to Figures 1 to 13The utility model provides a kind of secondary battery 100, battery pack 200 and electronic device 300, the secondary battery 100 can improve the technical problem that cover plate assembly 130 of existing secondary battery 100 is easily deformed under the action of internal pressure and influences the installation of secondary battery 100.

[0041] In the utility model, secondary battery 100 can include lithium ion battery, lithium-sulfur battery, sodium lithium ion battery, sodium ion battery or magnesium ion battery etc., the embodiment in the utility model is not limited to this.Further describe the structure of secondary battery 100, the secondary battery 100 includes: shell 110 and electrode assembly 120.

[0042] Shell 110 is formed with installation cavity inside, for installing electrode assembly 120, electrolyte (not shown) and other components.Specifically, the size of shell 110 can be determined according to the specific size of electrode assembly 120, for example diameter is 46mm, height is 80mm, 95mm, 120mm etc.standard.Great shell 110 can be multiple shapes, for example, cylinder, prism etc.Great shell 110 can also be multiple materials, such as copper, iron, aluminum, steel, aluminum alloy etc., to prevent rusting of shell 110 when long-term use, shell 110 can also be plated with a layer of anti-rust material on its surface, such as metal nickel etc.

[0043] Please refer to Figure 1 And Figure 2 In an embodiment of the utility model secondary battery 100, shell 110 is cylindrical structure, shell 110 includes end wall 113, side wall 111 around end wall 113 and cover plate assembly 130.Along the height direction of shell 110, one end (lower end) of side wall 111 is fixedly connected with end wall 113, forms closed end, and the other end (upper end) of side wall 111 is provided with opening 112.Cover plate assembly 130 is arranged at opening 112, and opening 112 is connected and sealed with side wall 111.

[0044] Please refer to Figure 1 And Figure 3 Electrode assembly 120 is arranged inside shell 110, and electrode assembly 120 is the component that electrochemical reaction occurs in secondary battery 100.Shell 110 can contain one or more electrode assemblies 120.Electrode assembly 120 includes pole piece and diaphragm, and pole piece and diaphragm are wound to form winding structure.Specifically, in the embodiment, electrode assembly 120 includes positive pole piece, diaphragm and negative pole piece wound axially around shell 110.

[0045] In general, the positive electrode tab includes a positive electrode current collector and a positive electrode active material layer coated on the positive electrode current collector, and the positive electrode current collector has a first coated area coated with the positive electrode active material layer and a first uncoated area not coated with the positive electrode active material layer, the first coated area and the first uncoated area are arranged axially along the shell 110, and the first uncoated area extends to the outside of the diaphragm at one end of the height direction of the secondary battery 100 and is bent to the axis of the shell 110 to form a stacked positive electrode tab. The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer coated on the negative electrode current collector, and the negative electrode current collector has a second coated area coated with the negative electrode active material layer and a second uncoated area not coated with the negative electrode active material layer, the second coated area and the second uncoated area are arranged axially along the shell 110, and the second uncoated area extends to the outside of the diaphragm at the other end of the height direction of the secondary battery 100 and is bent to the axis of the shell 110 to form a stacked negative electrode tab. The diaphragm is arranged between the positive electrode tab and the negative electrode tab to separate the positive electrode active material layer and the negative electrode active material layer. Taking the lithium ion secondary battery 100 as an example, the material of the positive electrode current collector can be aluminum, the positive electrode active material layer includes 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 includes a negative electrode active material, and the negative electrode active material can be carbon or silicon, etc. The base material of the diaphragm can be polypropylene (PP) or polyethylene (PE), 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, polyethylene terephthalate (PET), polyvinyl chloride (PVC) or other high molecular polymer materials.

[0046] Please continue to see Figure 1 and Figure 2 In an example of the secondary battery 100 of the utility model, the electrode assembly 120 is sealedly installed in the shell 110. The electrode assembly 120 is provided with the first tab 121 and the second tab 122 at both ends in the height direction of the secondary battery 100 respectively, and the polarity of the first tab 121 and the second tab 122 is opposite, wherein the first tab 121 faces the opening 112 of the shell 110, and the first tab 121 is a negative electrode tab. It should be noted that in other embodiments, the first tab 121 can also be a positive electrode tab, and the second tab 122 is a negative electrode tab.

[0047] Please see Figure 1In the secondary battery 100 example, a through terminal mounting hole is formed in the end wall 113 of the shell 110, and the electrode terminal 140 is sealingly and insulatingly fitted in the terminal mounting hole, as long as the sealing insulation between the electrode terminal 140 and the end wall 113 can be achieved, the mounting mode of the electrode terminal 140 on the end wall 113 is not limited. The side of the electrode assembly 120 facing the end wall 113 has a second tab 122, and one end of the electrode terminal 140 can be directly welded to the second tab 122, or can be electrically connected to the second tab 122 through a current collecting member, and no specific limitation is made thereto.

[0048] Please refer to Figures 2 to 4 The cover plate assembly 130 includes a first cover plate 131, a second cover plate 132, and a sealing plate 133. The first cover plate 131 covers the opening 112, and the outer edge of the first cover plate 131 is sealingly connected to the side wall 111 of the shell 110. The sealing connection mode can be various, such as welding sealing, mechanical pressure sealing, etc. The first cover plate 131 includes a through hole 1311, which can be located in the central region of the first cover plate 131, or can be offset from the central region. The shape of the through hole 1311 can also be various, such as a square hole, a round hole or other special-shaped hole, etc. Preferably, in order to facilitate the machining and positioning of the through hole 1311 on the first cover plate 131, in the embodiment, the first cover plate 131 is a disc-shaped structure, the through hole 1311 is a round hole structure, and the through hole 1311 is coaxially arranged with the first cover plate 131.

[0049] Please refer to Figure 2 and Figure 4 The second cover plate 132 is connected to the side of the first cover plate 131 close to the electrode assembly 120, and includes a liquid injection hole 1325 and a protrusion formed by stamping, which is marked as a first protrusion 1321 for convenience of description. The second cover plate 132 is connected to the first cover plate 131, and the connection mode can be welding connection, riveting connection, etc. The second cover plate 132 can be a disc shape matched with the through hole 1311, or can be other shapes capable of at least partially shielding the through hole 1311, such as a rectangular plate, a polygonal plate, etc. Preferably, in the embodiment, the second cover plate 132 is also a disc-shaped structure, and is coaxially arranged with the through hole 1311. In this way, the positioning and installation between the second cover plate 132 and the first cover plate 131 can be facilitated, which is beneficial to improving the assembly efficiency between the second cover plate 132 and the first cover plate 131. The liquid injection hole 1325 can be located in the central region of the second cover plate 132, or can be located in the region offset from the center of the second cover plate 132, so as to meet the liquid injection requirement of the electrode assembly 120. The first protrusion 1321 surrounds the outer periphery of the liquid injection hole 1325 and protrudes towards the first cover plate 131 side, and the first protrusion 1321 includes an annular platform 1322 exposed from the through hole 1311.

[0050] Please continue to see Figure 2 and Figure 4 , the inner periphery of the annular platform 1322 is bent and extends to form a stage 1323 on the side of the electrode assembly 120, and the surface of the sealing plate 133 away from the side of the electrode assembly 120 is lower than the surface of the first cover plate 131 away from the side of the electrode assembly 120. In the utility model, the second cover plate 132 is connected to the first cover plate 131 and provides a support platform for the sealing plate 133, thereby increasing the overall strength of the cover plate assembly 130. At the same time, the inner edge of the first protruding part 1321 on the second cover plate 132 forms a stage 1323, which can increase the overall strength of the lapping position of the sealing plate 133 and prevent deformation of the sealing plate 133. In addition, in the utility model, the surface of the sealing plate 133 away from the side of the electrode assembly 120 is lower than the surface of the first cover plate 131 away from the side of the electrode assembly 120, which can reduce the contact area between the secondary battery 100 and the tray during installation or placement of the secondary battery 100, thereby improving the reliability of the installation connection.

[0051] Please see Figure 2 , the side of the first cover plate 131 facing the electrode assembly 120 also includes a protruding part, which is marked as a second protruding part 1314 for ease of description. The second protruding part 1314 protrudes toward the side of the electrode assembly 120 and supports the first tab 121. It should be noted that the second protruding part 1314 can directly support the first tab 121, or indirectly support the first tab 121 through a conductive member such as a current collecting member. Figure 2 , the secondary battery 100 also includes a current collecting member 170, which is arranged in the housing 110 and located on the side of the electrode assembly 120 facing the cover plate assembly 130. The current collecting member 170 is welded to the first tab 121 and the housing 110 to achieve electrical connection. The second protruding part 1314 can be a ring structure arranged around, or a plurality of protruding structures arranged at intervals, or any structure that can support the first tab 121. The current collecting member 170 can be welded to the cover plate assembly 130, or to the side wall 111, or to both the cover plate assembly 130 and the side wall 111. The specific position and welding area of the current collecting member 170 welded to the first tab 121 are not limited, as long as it can achieve stable electrical connection between the current collecting member 170 and the first tab 121. The side of the second protruding part 1314 facing the electrode assembly 120 abuts against the current collecting member 170, and the current collecting member 170 abuts against the first tab 121 below, thereby indirectly supporting the second protruding part 1314 and the first tab 121.

[0052] In this utility model, the connection method between the second cover plate 132 and the first cover plate 131 can be any method that can achieve a fixed connection between the first cover plate 131 and the second cover plate 132, such as welding or riveting. Please refer to [link to relevant documentation]. Figure 2 , Figure 3 In some embodiments of the secondary battery 100 of this utility model, the second cover plate 132 is welded to the side of the first cover plate 131 near the electrode assembly 120. Please refer to [link / reference]. Figure 6 , Figure 7 In some other embodiments of the secondary battery 100 of this utility model, the second cover plate 132 is riveted to the side of the first cover plate 131 near the electrode assembly 120.

[0053] In this utility model, the sealing plate 133 can be welded to the first cover plate 131, or to the second cover plate 132, or simultaneously to both the first cover plate 131 and the second cover plate 132. (See also...) Figure 2 In one embodiment of the secondary battery 100 of this utility model, the sealing plate 133 and the first cover plate 131 are welded together by a first weld mark 150a. The first weld mark 150a is disposed between the outer periphery of the sealing plate 133 and the side wall of the through hole 1311. Specifically, the first weld bead surrounds the outer periphery of the sealing plate 133 and forms a molten pool between the sealing plate 133 and the side wall of the through hole 1311. In this case, if the molten pool is shallow and does not reach the second cover plate 132, the sealing plate 133 is only welded and fixed to the first cover plate 131. If the molten pool is deep and the melting depth is greater than the thickness of the first cover plate 131 at the corresponding position of the first protrusion 1321, the sealing plate 133 is welded and fixed to both the first cover plate 131 and the second cover plate 132.

[0054] Please see Figure 3 ,and Figure 2 Unlike the previous embodiment, in another embodiment of the secondary battery 100 of this utility model, the sealing plate 133 and the second cover plate 132 are welded together by a second weld mark 150b. The second weld mark 150b is disposed in the overlapping area of ​​the sealing plate 133 and the annular platform 1322. During welding, welding is performed from one side of the sealing plate 133. The molten pool opening of the second weld mark 150b is formed on the sealing plate 133, and the depth of the molten pool of the second weld mark 150b is less than the sum of the thicknesses of the sealing plate 133 and the second cover plate 132 at the location of the second weld mark 150b. Distributing the molten pool opening on the sealing plate 133 facilitates laser welding after liquid injection. Furthermore, setting the depth of the second weld mark 150b to be less than the total thickness of the overlapping area at the location of the second weld mark 150b (i.e., the sum of the thicknesses of the first cover plate 131 and the second cover plate 132 corresponding to the location of the second weld mark 150b) prevents weld slag from entering the battery interior, thereby improving battery safety.

[0055] Please see Figure 2 andFigure 4 In the embodiment of the secondary battery 100 of the utility model, the through hole 1311 is circular, the sealing plate 133 is disc-shaped, the annular platform 1322 is also circular ring-shaped coaxially arranged with the sealing plate 133, the lap width of the sealing plate 133 and the annular platform 1322 is W1 (namely the overlapping width of the sealing plate 133 and the annular platform 1322 along the radial direction), the diameter of the sealing plate 133 is M, wherein the value of W1 / M is between 10% and 20%, for example, can be 10%, 15% or 20% and any value between 10% and 20%. Specifically, considering the existing specification series of the secondary battery 100, the diameter of the sealing plate 133 is 5mm to 20mm, and the width of W1 is between 0.5mm and 4mm. By limiting the ratio of W1 and M, on the one hand, sufficient space can be provided to obtain a larger liquid injection hole 1325 size, and on the other hand, due to the shielding of the second cover plate 132, the sealing plate 133 can also have a smaller internal pressure acting area, which can reduce the deformation force on the second cover plate 132, and effectively reduce the deformation of the sealing plate 133 under the action of internal pressure.

[0056] Please refer to Figure 2 In the embodiment of the secondary battery 100 of the utility model, the second cover plate 132 is welded to the first cover plate 131 through the third welding mark 160a, the molten pool opening of the third welding mark 160a is located on the second cover plate 132, and the molten pool depth of the third welding mark 160a is less than the total thickness of the first cover plate 131 and the second cover plate 132 at the position of the third welding mark 160a. Please refer to Figure 3 In another embodiment of the secondary battery 100 of the utility model, the second cover plate 132 is welded to the first cover plate 131 through the third welding mark 160b, the molten pool opening of the third welding mark 160b is located on the first cover plate 131, and the molten pool depth of the third welding mark 160b is less than the total thickness of the first cover plate 131 and the second cover plate 132 at the position of the third welding mark 160b. In the two schemes, the second cover plate 132 and the first cover plate 131 can be integrated and welded together before the first cover plate 131 and the side wall 111 of the shell 110 are welded, which can reduce the process flow after the electrode assembly 120 is loaded into the shell 110, and can effectively reduce the foreign matter entering the inside of the shell 110 caused by welding after the electrode assembly 120 is loaded into the shell 110. Please refer to Figure 2 When the molten pool opening of the third welding mark is on the first cover plate 131, welding needs to be performed from the first cover plate 131 at this time, and by making the molten pool depth less than the total thickness of the first cover plate 131 and the second cover plate 132 at the position of the third welding mark 160a, the third welding mark 160a can not be exposed to the surface of the second cover plate 132 towards the electrode assembly 120, which can reduce the corrosion of the electrolyte on the third welding mark 160a. Please refer to Figure 3When the molten pool opening of the third welding mark 160b is on the second cover plate 132, welding needs to be performed from the side of the second cover plate 132, and by making the molten pool depth less than the total thickness of the first cover plate 131 and the second cover plate 132 at the position where the third welding mark 160b is located, the third welding mark 160b can be prevented from being exposed to the surface of the side of the first cover plate 131 away from the electrode assembly 120, and the corrosion of the third welding mark 160b by water vapor in the atmospheric environment or working environment can be reduced.

[0057] In view of the conventional size series of the existing secondary battery 100 and the requirement that the third welding mark not be welded through, preferably, referring to Figure 2 In an embodiment of the secondary battery 100 of the utility model, the second cover plate is provided with a third protruding portion 1324, the third protruding portion 1324 is arranged around the first protruding portion 1321, the third welding mark 160a is arranged in the contact area between the third protruding portion 1324 and the first cover plate 131, the thickness D of the second cover plate 132 (at the third protruding portion 1324) at the corresponding position of the third welding mark 160a is 0.3 mm to 0.8 mm, for example, can be 0.3 mm, 0.5 mm or 0.8 mm or any value between 0.3 mm and 0.8 mm; the thickness C of the first cover plate 131 at the corresponding position of the third welding mark 160a is 0.3 mm to 0.8 mm, for example, can be 0.3 mm, 0.5 mm or 0.8 mm or any value between 0.3 mm and 0.8 mm. Limiting the thickness of the first cover plate 131 and the second cover plate 132 at the third welding mark to 0.3 mm to 0.8 mm can appropriately increase the process window of laser welding, and reduce the difficulty of laser welding.

[0058] It should be noted that the first cover plate 131 and the second cover plate 132 in the utility model can also be connected together by other means, for example, referring to Figure 6 、 Figure 7 In an embodiment of the secondary battery 100 of the utility model, the second cover plate 132 and the first cover plate 131 are rivetedly connected, one of the second cover plate 132 and the first cover plate 131 is provided with a riveting groove 1313, the other of the second cover plate 132 and the first cover plate 131 is provided with a riveting boss 1326, the riveting boss 1326 corresponds to the riveting groove 1313 and is deformed and clamped into the riveting groove 1313 after riveting. Specifically, in the embodiment, the first cover plate 131 is provided with the riveting groove 1313, the second cover plate 132 is provided with the riveting boss 1326, the position of the riveting boss 1326 corresponds to the riveting groove 1313 and is deformed and clamped into the riveting groove 1313 after riveting. However, as can be understood by those skilled in the art, the second cover plate 132 can also be provided with the riveting groove 1313, and the first cover plate 131 can be provided with the riveting boss 1326, the position of the riveting boss 1326 corresponds to the riveting groove 1313 and is deformed and clamped into the riveting groove 1313 after riveting.

[0059] Please refer to Figure 6 、 Figure 7 In an embodiment of the secondary battery 100 of the utility model, the thickness of the first cover plate 131 and the second cover plate 132 at the riveting position is 0.3mm to 0.8mm, the width of the riveting groove 1313 is 0.2mm to 3mm, for example, it can be 0.2mm, 1mm, 2mm or 3mm or any value between 0.2mm and 3mm; The depth is 0.05mm to 0.4mm, for example, it can be 0.05mm, 0.1mm, 0.3mm or 0.4mm or any value between 0.05mm and 0.4mm, which can improve the stability of riveting of the first cover plate 131 and the second cover plate 132 in the thin thickness range, can prevent the riveting groove 1313 from being too shallow to cause insufficient riveting strength, and can prevent the riveting groove 1313 from being too deep to cause the riveting boss to break through the bottom of the riveting groove 1313 during the riveting process.

[0060] Please refer to Figure 9 、 Figure 11 In an embodiment of the utility model secondary battery 100, the side wall of the through hole 1311 close to the electrode assembly 120 is provided with a gap 1312 capable of partially containing molten metal, and the gap 1312 is one or a combination of groove, chamfer, round corner. The gap 1312 can absorb the molten metal material, on the one hand, it can reduce the probability of the welding mark protruding to the surface of the first cover plate 131, on the other hand, it can accommodate the molten metal material, increase the area of the first cover plate 131, the sealing plate 133 and the molten pool corresponding combination, can increase the stability of the welding between the first cover plate 131 and the sealing plate 133.

[0061] Please refer to Figure 8 and Figure 9In the secondary battery 100 of the embodiment of the utility model, the notch 1312 is a groove, the width W2 of the groove ranges from 0.1mm to 2.0mm, and the depth H1 of the groove ranges from 0.1mm to 0.4mm. Specifically, the groove is a circular ring shape and is arranged on one side of the side wall of the through hole 1311 close to the electrode assembly 120 in a radial direction. The width W2 of the groove can be 0.1mm, 0.5mm, 1mm or 2.0mm, etc. any value between 0.1mm and 2.0mm, and the depth H1 of the groove can be 0.1mm, 0.3mm or 0.4mm, etc. any value between 0.1mm and 0.4mm. Under this groove shape, the depth range and the width range can not only ensure enough space to accommodate the molten metal, but also ensure that the side wall of the through hole 1311 above the groove has enough strength to provide strong welding strength for the cover plate.

[0062] Please refer to Figure 10 and Figure 11 In another embodiment of the secondary battery 100 of the utility model, the notch 1312 is a chamfer, the width W3 of the chamfer in the radial direction ranges from 0.1mm to 0.5mm, and the height H2 in the height direction of the shell 110 ranges from 0.1mm to 0.5mm. Specifically, W3 can be 0.1mm, 0.3mm, 0.5mm, etc. any value between 0.1mm and 0.5mm, and H2 can be 0.1mm, 0.3mm, 0.5mm, etc. any value between 0.1mm and 0.5mm. Under the shape of the chamfer, the width and height can not only ensure that the chamfer position has enough space to accommodate the molten metal, but also ensure that the side wall of the through hole 1311 above the chamfer has enough strength to provide strong welding strength for the cover plate.

[0063] It should be noted that in other embodiments of the secondary battery 100 of the utility model, the notch 1312 can also be a round corner, and the radius of the round corner is 0.1mm to 0.5mm. Specifically, it can be 0.1mm, 0.3mm, 0.5mm, etc. any value between 0.1mm and 0.5mm. Under the shape of the round corner, the width and height can not only ensure that the chamfer position has enough space to accommodate the molten metal, but also ensure that the side wall of the through hole 1311 above the chamfer has enough strength to provide strong welding strength for the cover plate.

[0064] Please refer to Figure 12In an embodiment of the battery pack 200, the battery pack 200 comprises a box body 210 and at least one secondary battery 100; the box body 210 comprises a first box body part 211 and a second box body part 212, the first box body part 211 and the second box body part 212 are mutually covered to form an accommodating space, a plurality of secondary batteries 100 are accommodated in the accommodating space, and the plurality of secondary batteries 100 can be connected in series and / or in parallel. The battery pack 200 may, for example, be a battery module, a battery pack, etc.

[0065] Please refer to Figure 13 In an example of the electronic device 300, the electronic device 300 comprises a working part 310 and a battery pack 200, and the working part 310 is electrically connected with the battery pack 200 to obtain power support. The working part 310 can be a unit component capable of obtaining the power of the battery pack 200 and making corresponding work, such as a fan blade rotating unit, a dust suction working unit of a dust collector, a wheel driving unit in an electric vehicle, etc. The electronic device 300 can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle can be a fuel automobile, a gas automobile or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile or a range extended automobile, etc.; the spacecraft comprises an airplane, a rocket, a space shuttle and a spacecraft, etc.; the electric toy comprises a fixed or mobile electric toy, such as a game machine, an electric automobile toy, an electric ship toy and an electric airplane toy, etc.; the electric tool comprises a metal cutting electric tool, a grinding electric tool, an assembling electric tool and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator and an electric planer, etc. The electronic device 300 is not specially limited in the embodiments of the present application. In an embodiment of the electronic device 300, the electronic device 300 is a vehicle, the working part 310 is a vehicle body, and the battery pack 200 is fixedly installed on the vehicle body, thereby providing driving force for the vehicle and realizing the running of the vehicle.

[0066] In summary, the cover plate assembly of the secondary battery comprises the first cover plate and the second cover plate arranged in a split manner, the second cover plate is connected to the first cover plate and provides a support platform for the sealing plate, and the overall strength of the cover plate assembly is increased. Meanwhile, the inner edge of the convex part on the second cover plate is formed with a stage, which can increase the overall strength of the lap joint position of the sealing plate and prevent the deformation of the sealing plate part. In addition, the surface of the sealing plate away from the electrode assembly is lower than the surface of the first cover plate away from the electrode assembly, which can reduce the contact area between the secondary battery and the tray during the installation or placement of the secondary battery, and improve the reliability of the installation connection. Therefore, the present application effectively overcomes some practical problems in the prior art and has high utilization value and use significance.

[0067] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A secondary battery characterized by comprising: The application relates to a battery case. The battery case comprises: a case body comprising a side wall with an open end and a cover plate assembly covering the opening; an electrode assembly arranged in the case body; the cover plate assembly comprises: a first cover plate covering the opening and being in sealing connection with the side wall, the first cover plate comprising a through hole; a second cover plate connected to the first cover plate on the side close to the electrode assembly and comprising a liquid injection hole and a stamped protrusion, the protrusion being annularly arranged around the liquid injection hole and protruding towards the first cover plate, the protrusion comprising an annular platform exposed from the through hole; a sealing plate, the outer periphery of the sealing plate being overlapped on the annular platform and being welded to the first cover plate and / or the second cover plate to seal the liquid injection hole; 2. The secondary battery according to claim 1, characterized by wherein the inner periphery of the annular platform is bent to extend towards the electrode assembly to form a stage, and the surface of the sealing plate away from the electrode assembly is lower than the surface of the first cover plate away from the electrode assembly.

3. The secondary battery according to claim 1, characterized by The second cover plate is welded or riveted to the first cover plate on the side close to the electrode assembly.

4. The secondary battery according to claim 1, characterized by The sealing plate and the first cover plate are welded by a first welding mark arranged between the outer periphery of the sealing plate and the side wall of the through hole.

5. The secondary battery according to claim 1, characterized by The sealing plate and the second cover plate are welded by a second welding mark arranged in the overlapping area of the sealing plate and the annular platform, the molten pool opening of the second welding mark being located on the sealing plate, and the molten pool depth of the second welding mark in the overlapping area being smaller than the total thickness of the second cover plate and the sealing plate at the position of the second welding mark.

6. The secondary battery according to claim 1, characterized by The sealing plate is disc-shaped, the annular platform is also annular and coaxially arranged with the sealing plate, the overlapping width of the sealing plate and the annular platform is W1, and the diameter of the sealing plate is M, wherein the value of W1 / M is between 10% and 20%.

7. The secondary battery according to claim 6, characterized by The second cover plate is welded to the first cover plate by a third welding mark, the molten pool opening of the third welding mark being located on the second cover plate or the first cover plate, and the molten pool depth of the third welding mark being smaller than the total thickness of the first cover plate and the second cover plate at the position of the third welding mark.

8. The secondary battery according to claim 1, characterized by The thickness of the second cover plate at the position corresponding to the third welding mark is 0.3mm to 0.8mm, and the thickness of the first cover plate is 0.3mm to 0.8mm.

9. The secondary battery according to claim 8, characterized by The second cover plate and the first cover plate are riveted, one of the second cover plate and the first cover plate is provided with a riveting groove, and the other of the second cover plate and the first cover plate is provided with a riveting boss corresponding to the riveting groove and deformed to be clamped in the riveting groove after riveting.

10. The secondary battery according to claim 1, characterized by The width of the riveting groove is 0.2mm to 3mm, and the depth is 0.05mm to 0.4mm.

11. The secondary battery according to claim 10, characterized by The side wall of the through hole on the side close to the electrode assembly is provided with a notch capable of partially containing molten metal, the notch being one or a combination of a groove, a chamfer and a round corner. The notch is a groove, the width W2 of the groove ranges from 0.1mm to 2.0mm, and the depth H1 of the groove ranges from 0.1mm to 0.4mm.

12. The secondary battery according to claim 10, characterized by The notch is a chamfer, and a width W3 of the chamfer along the radial direction is 0.1 mm to 0.5 mm, and a height H2 in the height direction of the housing is 0.1 mm to 0.5 mm.

13. The secondary battery according to claim 10, characterized by The notch is a round corner, and a radius of the round corner is 0.1 mm to 0.5 mm.

14. A battery pack, characterized by A secondary battery including any one of claims 1 to 13.

15. An electronic device, comprising: A battery pack including claim 14.

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