Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a kind of secondary battery, battery pack and electronic device, secondary battery includes: shell, including the first side wall of encirclement, and the at least one end of first side wall forms opening;Electrode assembly is set in shell;Cover plate is closed on opening, cover plate has with the outer periphery of opening welding, and with the support portion of outer periphery interface, support portion is set as protruding towards electrode assembly, and the outer surface of support portion away from electrode assembly is recessed;Current collector is set between cover plate and electrode assembly;Wherein, the bottom wall of recess is welded with current collector and forms welding portion, wherein, along the radial bottom wall of shell has center line;In radial, the distance between welding portion and first side wall is D1, the distance between center line and first side wall is D2, D1>D2.The utility model at least reduces the heat effect of cover plate and current collector welding to the opening of shell, avoid the deformation of the opening of shell.

Description

Technical Field

[0001] This utility model relates to a secondary battery, a battery pack, and an electronic device. Background Technology

[0002] In the field of new energy batteries, the application of rechargeable batteries is becoming increasingly widespread. These batteries (such as lithium-ion batteries) can be used in electronic devices such as vehicles, energy storage, mobile phones, tablets, wearable devices, power banks, e-cigarettes, digital products, power tools, power units, and energy storage devices. A rechargeable battery typically consists of a casing and electrode assemblies. The electrode assembly includes a positive electrode, a first separator, a negative electrode, and a second separator. These are stacked sequentially to form a wound electrode assembly or a stacked electrode assembly, which is then placed inside the casing and sealed with a cover that closes the casing opening.

[0003] The cover plate needs to be welded to the opening of the secondary battery casing in the circumferential direction, and the cover plate also needs to be welded to the current collector of the electrical connection electrode assembly. However, welding the cover plate to the current collector will have a thermal effect on the opening of the casing, causing the opening to deform. Utility Model Content

[0004] In view of the problems existing in the related technologies, the purpose of this utility model is to provide a secondary battery, battery pack and electronic device, so as to at least reduce the thermal impact of the welding of the cover plate and the current collector on the opening of the shell and avoid deformation of the opening of the shell.

[0005] To achieve the above objectives, this utility model provides a secondary battery, comprising: a housing including a surrounding first sidewall, at least one end of the first sidewall forming an opening; an electrode assembly disposed in the housing; a cover plate covering the opening, the cover plate having an outer periphery welded to the opening and a support portion connected to the outer periphery, the support portion being configured to protrude toward the electrode assembly, and the support portion having a groove on the outer surface away from the electrode assembly; a current collector disposed between the cover plate and the electrode assembly; wherein the bottom wall of the groove is welded to the current collector to form a welded portion; a centerline is provided along the radial bottom wall of the housing; in the radial direction, the distance between the welded portion and the first sidewall is D1, and the distance between the centerline and the first sidewall is D2, where D1 > D2.

[0006] In some embodiments, the electrode assembly is a wound member having a winding center hole, the current collector is provided with a weak portion, the projection of the weak portion along the axis of the housing at least partially coincides with the winding center hole, the weak portion is configured to tear in the event of thermal runaway of the secondary battery, the current collector includes a first connection portion welded to a support portion, and the weak portion is offset toward the cover plate relative to the first connection portion.

[0007] In some embodiments, a rounded transition region is provided between at least one second sidewall of the groove and the bottom wall; in the radial direction, the distance between the rounded transition region located radially inside the weld and the weld is W1 mm, where W1 ≥ 0.1.

[0008] In some embodiments, the width of the welded portion in the radial direction is W2mm; the distance between the opposite second sidewalls of the groove in the radial direction is W3mm, wherein 0.13≤W2 / W3≤0.5.

[0009] In some embodiments, the cover plate is provided with a plurality of supports arranged circumferentially around the axis of the housing, and an exhaust channel extending radially along the housing is formed between each pair of adjacent supports.

[0010] The total length of the bottom wall of each support component extending in the circumferential direction is P1, the plane on which the bottom wall is located is the reference plane, each exhaust channel has a cross-section on the reference plane, and the total length of each cross-section extending in the circumferential direction is P2, 0.12≤P2 / P1≤0.7.

[0011] In some embodiments, the cover plate is provided with grooves configured to crack to release pressure in the event of thermal runaway of the secondary battery; wherein, in the radial direction, the grooves are closer to the axis than the support portion.

[0012] In some embodiments, the radial distance between the notch and the support is f mm, where 2 ≤ f ≤ 8.

[0013] In some embodiments, the projection of the support portion along the axis of the housing is arc-shaped, and the weld portion is an arc-shaped weld line.

[0014] Embodiments of this application also provide a battery pack, including any of the above-described secondary batteries.

[0015] Embodiments of this application also provide an electronic device including a battery pack of any of the above.

[0016] The beneficial technical effects of this utility model are at least as follows:

[0017] The embodiments of this application at least reduce the thermal impact of welding the cover plate and the manifold on the opening of the housing, and avoid deformation of the opening of the housing. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of an electronic device, using a vehicle as an example, is shown.

[0020] Figure 2 A perspective view of a secondary battery according to an embodiment of this application is shown.

[0021] Figure 3 A top view schematic diagram of a secondary battery according to an embodiment of this application is shown.

[0022] Figure 4 It shows along Figure 3 A schematic diagram of a cross-section taken from the CC section.

[0023] Figure 5 A top view schematic diagram of a secondary battery according to an embodiment of this application is shown.

[0024] Figure 6 It shows along Figure 5 A schematic diagram of a cross-section taken from the DD section.

[0025] Figure 7 It shows Figure 6 A magnified view of a portion of region A in the middle.

[0026] Figure 8 It shows Figure 4 Enlarged schematic diagram of region B in the middle.

[0027] Figure 9 and Figure 10 A three-dimensional schematic diagram of a cover plate according to some embodiments of this application is shown. Detailed Implementation

[0028] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0029] Embodiments of this application will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are indicated by similar reference numerals. The embodiments described herein with reference to the accompanying drawings are illustrative and diagrammatic in nature and are intended to provide a basic understanding of this application. The embodiments of this application should not be construed as limiting this application.

[0030] As used herein, the terms “approximately,” “generally,” “substantially,” and “about” are used to describe and indicate minor variations. When used in conjunction with an event or situation, these terms may refer to examples in which the event or situation occurred precisely or in examples in which the event or situation occurred very approximately.

[0031] In this specification, unless otherwise specified or limited, relative terms such as “central,” “longitudinal,” “lateral,” “front,” “rear,” “right,” “left,” “inner,” “outer,” “lower,” “higher,” “horizontal,” “vertical,” “above,” “below,” “above,” “below,” “top,” “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to the directions described in the discussion or depicted in the accompanying drawings. These relative terms are used for descriptive convenience only and do not require that this application be constructed or operated in a particular orientation.

[0032] For ease of description, "first," "second," "third," etc., can be used in this article to distinguish different components of a figure or a series of figures. "First," "second," "third," etc., are not intended to describe the corresponding components.

[0033] See Figure 1 This utility model provides an electronic device 1000, which includes a battery pack 1002. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain electrical power. As an example, the electronic device 1000 is a vehicle, which can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, but are not limited thereto. The working part is the vehicle body, and the battery pack 1002 is located at the bottom of the vehicle body, providing electrical power for the vehicle's operation or the operation of its internal electrical components. However, in other embodiments, the electronic device 1000 can also be a mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working part can obtain electrical power from the battery pack 1002 and perform corresponding functions, such as a fan blade rotation unit or a vacuum cleaner suction unit. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the aforementioned electronic device 1000.

[0034] For ease of explanation, the following embodiments use a vehicle as an example to illustrate the concept of electronic device 1000. See also Figure 1The vehicle is equipped with a battery pack 1002, which can be located at the bottom, front, or rear of the vehicle body 1001. The battery pack 1002 can be used to power the vehicle; for example, it can serve as the vehicle's operating power source. Figure 2 A perspective view of a secondary battery 100 according to an embodiment of this application is shown.

[0035] Figure 3 A top view schematic diagram of a secondary battery 100 according to an embodiment of this application is shown. Figure 4 It shows along Figure 3 A cross-sectional view taken from the CC section. See also the example of the secondary battery of this utility model. Figure 2 , Figure 3 as well as Figure 4 The electrode assembly 120 is sealed and installed within the housing 200. The electrode assembly 120 has a first electrode tab and a second electrode tab at both ends of the secondary battery 100 along its height direction, and the first and second electrode tabs have opposite polarities, with the first electrode tab facing the opening side and being the negative electrode tab. It should be noted that in other embodiments, the first electrode tab can also be the positive electrode tab, and the second electrode tab can be the negative electrode tab.

[0036] The electrode assembly 120 of the secondary battery 100 is mainly formed by winding and placing a positive electrode sheet and a negative electrode sheet, and typically a first separator and a second separator are provided between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive current collector and a positive active material layer, the positive active material layer being coated on the surface of the positive current collector; the positive current collector includes a positive electrode coating area and a positive electrode tab connected to the positive electrode coating area, the positive electrode coating area being coated with the positive active material layer, and the positive electrode tab not being coated with the positive active material layer. The negative electrode sheet includes a negative current collector and a negative active material layer, the negative active material layer being coated on the surface of the negative current collector; the negative current collector includes a negative electrode coating area and a negative electrode tab connected to the negative electrode coating area, the negative electrode coating area being coated with the negative active material layer, and the negative electrode tab not being coated with the negative active material layer. Taking a lithium-ion battery as an example, the positive electrode current collector can be made of aluminum, and the positive electrode active material layer includes positive electrode active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode current collector can be made of copper, and the negative electrode active material layer includes negative electrode active material, which can be carbon or silicon, etc. The first and second separators can be made of PP or PE, etc. To protect and insulate the electrode assembly 120, an insulating film can be wrapped around the outside of the electrode assembly 120. The insulating film can be synthesized from PP, PE, PET, PVC, or other polymer materials.

[0037] In some embodiments, the housing 200 is made of materials such as copper, iron, aluminum, steel, or aluminum alloy, preferably steel (e.g., SPCC) for higher strength. To prevent the housing 200 from rusting during long-term use, a rust-preventive material such as metallic nickel can be plated on the surface of the housing 200. The electrode assembly 120 is sealed and installed inside the housing 200.

[0038] Figure 5 A top view schematic diagram of a secondary battery 100 according to an embodiment of this application is shown. Figure 6 It shows along Figure 5 A schematic diagram of a cross-section taken from the DD section. Further, Figure 7 It shows Figure 6 A magnified view of a portion of region A in the middle. Figure 7 For ease of understanding, a sectional view will be used as an example. See also... Figure 5 , Figure 6 ,as well as Figure 7According to an embodiment of this application, the secondary battery 100 includes: a housing 200, the housing 200 having a surrounding first sidewall 112, at least one end of the first sidewall 112 being an opening 201; an electrode assembly 120 disposed in the housing 200; and a cover plate 300 covering the opening, the cover plate 300 having an outer peripheral edge 301 welded to the opening 201, and a support portion 302 connected to the outer peripheral edge 301, the support portion 302 being configured to protrude toward the electrode assembly 120 and to move away from the electrode assembly 120. The cover plate 300 has a groove on its outer surface; the collector plate 400 is disposed between the cover plate 300 and the electrode assembly 120; wherein the bottom wall 3021 of the groove is welded to the collector plate 400 to form a welded part 500, wherein the bottom wall 3021 has a center line G along the radial X of the housing 200, the center line G bisects the bottom wall 3021 in the radial X, and the distance between the welded part 500 and the first side wall 112 in the radial X is D1, and the distance between the center line G and the first side wall 112 is D2, D1>D2. It is understandable that when assembling the cover plate 300 to the housing 200, if the cover plate 300 is first welded to the manifold 400 and then welded to the first side wall 112 of the housing 200, the opening 201 of the housing 200 will be deformed by the heat of welding when the cover plate 300 and the manifold 400 are welded to form the welded part 500. This will make it difficult to weld the cover plate 300 and the first side wall 112 due to heat deformation, resulting in a reduced welding yield. If the cover plate 300 is first welded to the first side wall 112 of the housing 200 and then welded to the manifold 400, the heat from the subsequent welding of the cover plate 300 and the manifold 400 may cause the weld between the cover plate 300 and the first side wall 112 of the housing 200 to break or fail. To prevent the welding of the support portion 302 of the cover plate 300 to the collector plate 400 from having a thermal impact on the opening 201 of the housing 200, the welding point of the support portion 302 and the collector plate 400 is set to be offset from the center line G towards the first side wall 112 away from the housing 200. Specifically, the distance D1 between the welding portion 500 and the first side wall 112 is set to be greater than the distance D2 between the center line G and the first side wall 112, thereby preventing the opening 201 of the housing 200 from being deformed due to thermal impact.

[0039] It can also be understood that the centerline G can be the centerline G between the two second sidewalls 3022 of the groove. The current collector 400 includes a first connecting portion 402 welded to the support portion 302, and a second connecting portion 403 connected to and surrounded by the first connecting portion 402. The second connecting portion 403 is configured to be welded to the tab of the electrode assembly 120. In some embodiments, the electrode assembly 120 is a wound member having a winding center hole 121, and the current collector 400 is provided with a weak portion 401 at a position corresponding to the winding center hole 121. The weak portion 401 is configured to tear in the event of thermal runaway of the secondary battery 200. The weak portion 401 can be a thinned portion of the current collector 400, and the projection of the weak portion 401 along the axis H of the housing 200 at least partially coincides with the winding center hole 121. The second connecting part 403 is offset towards the cover plate 300 compared to the first connecting part 402, thus making the current collector 400 as a whole funnel shape, which facilitates the timely tearing of the weak part 401 in the event of thermal runaway of the secondary battery 100. Of course, the weak part 401 can also be... Figure 7 The example shown is an opening in the current collector 400 corresponding to the portion of the winding center hole 121. The opening can be rectangular, cross-shaped, or have other reasonable configurations. By providing a weak portion 401, it is easier for the current collector 400 to be torn apart in the event of thermal runaway of the secondary battery 100. Furthermore, the second connecting portion 403 is offset towards the cover plate 300 compared to the first connecting portion 402, resulting in a smaller gap between the inner side of the first connecting portion 402 and the cover plate 300. This facilitates the welding of the bottom wall 3021 of the groove to the current collector 400 at a position away from the first side wall 112 of the housing 200 to form a weld portion 500.

[0040] In some embodiments, a rounded transition region 3023 is provided between at least one second sidewall 3022 of the groove and the bottom wall 3021. In the radial direction X, the distance between the rounded transition region 3023 located radially inside the weld portion 500 and the weld portion 500 is W1 mm, where W1 ≥ 0.1. If the distance W1 mm ​​is set to be small, for example, W1 < 0.1, the rounded transition region 3023 will also be affected by thermal deformation, resulting in a further weakening of the structural strength of the rounded transition region 3023.

[0041] Furthermore, in the radial direction X, the width of the welded portion 500 is W2mm; the distance between the opposite second sidewalls 3022 of the groove in the radial direction X is W3mm, preferably 0.13≤W2 / W3≤0.5. When the cover plate 300 is assembled into the housing 200, the tooling presses against the groove, so that the outer periphery 301 of the cover plate 300 abuts against the first sidewall 112 of the housing 200, and the support portion of the cover plate 300 abuts against the collector plate 400. If the ratio is small, for example 0.13>W2 / W3, the weld strength of the welded portion 500 is low, and the welded portion 500 is easy to break under force; if the ratio is large, for example W2 / W3>0.5, the formed groove is narrower, and during the process of the tooling extending into the groove to press the outer periphery 301 of the cover plate 300 against the housing opening, the contact area between the tooling and the cover plate 300 is too small, avoiding damage to the groove when the tooling provides extrusion force. In some embodiments, the projection of the support portion 302 along the axis H of the housing 200 is arc-shaped, and the welding portion 500 is an arc-shaped weld line.

[0042] Figure 8 It shows Figure 4 A magnified view of region B in the middle. See also... Figure 3 , Figure 4 , Figure 5 as well as Figure 8 In some embodiments, the cover plate 300 is provided with a plurality of support portions 302 arranged circumferentially around the axis H of the housing 200. An exhaust channel 303 extending radially along the housing is formed between each pair of adjacent support portions 302. The support portion 302 has a groove on its outer surface facing away from the electrode assembly 20. The projection of the support portion 302 along the axis a of the housing is arc-shaped. The bottom wall 3021 of the groove facing the electrode assembly 120 is welded to the collector plate 120 to form an arc-shaped weld line. The total length of the bottom wall 3021 of each support portion 302 extending in the circumferential direction is P1. The plane containing the bottom wall 3021 is a reference plane. Each exhaust channel has a cross-section on the reference plane, and the total length of each cross-section extending in the circumferential direction is P2, where 0.12 ≤ P2 / P1 ≤ 0.7. If the proportion of the support portion 302 is small, for example, the ratio of P2 to P1 is greater than 0.7, then the total length of the support portion 302 extending in the circumferential direction is reduced, and correspondingly, the extendable length of the weld portion 500 on the support portion 302 is smaller, resulting in a weaker connection strength between the support portion 302 and the current collector 400. If the proportion of the support portion 302 is too large, for example, the ratio of P2 to P1 is less than 0.12, then the cross-sectional area of ​​the exhaust channel 303 is small, and when the secondary battery experiences thermal runaway, the gas generated by the electrode plates around the electrode assembly 120 is difficult to exhaust to the space near the notch 304 of the cover plate 300. It can be seen that... Figure 5 The illustration shows the length L1 of the cross-section of a single exhaust passage 303 extending in the circumferential direction and the length L2 of the bottom wall 3021 of a single support 302 extending in the circumferential direction.

[0043] See also Figure 6 and Figure 7 In some embodiments, the cover plate 300 is further provided with a notch 304, which is configured to crack to relieve pressure in the event of thermal runaway of the secondary battery 100. The notch 304 can be a circle circumferentially surrounding the axis H of the housing 200, or it can be multiple arcs arranged circumferentially around the axis H of the housing 200, or even arranged on the same circumference. The notch 304 in this embodiment is not limited to this, and the notch 304 can have any shape to facilitate cracking to relieve pressure in the event of thermal runaway of the secondary battery 100. In the radial direction X, the notch 304 is closer to the axis H than the support portion 302. Setting the notch 304 closer to the axis H in the radial direction X than the support portion 302 can prevent the tooling fixture from directly pressing the notch 304 when it is inserted into the groove of the support portion 302.

[0044] In the radial direction X, the distance between the notch 304 and the support 302 is f mm, where 2 ≤ f ≤ 8. If f is too small, for example, f < 2, the notch 304 is prone to deformation when the tooling presses against the groove, affecting the valve pressure. If f is too large, for example, f > 8, the area of ​​the notch will be too small, resulting in insufficient venting area under thermal runaway conditions, making the housing 200 prone to bursting or the terminal of the secondary battery 100 prone to flying out. The collector plate 400 may include a body 404 and a transition ring 405 welded to the surface of the body 404 facing the cover plate 300. The bottom wall 3021 of the groove is welded to the transition ring 405. Furthermore, the material of the body 404 may be copper, and the material of the transition ring 405 may be steel. Of course, it can also be understood that the first connecting part 402 welded to the support 302 is either the part where the body 404 and the transition ring 405 are welded to the support 302, or it may be the part where the transition ring 405 is welded to the support 302.

[0045] Figure 9 and Figure 10 A three-dimensional schematic diagram of a cover plate 300 according to some embodiments of this application is shown.

[0046] Figure 9 The example shown is the side of the cover plate 300 facing outwards from the housing 200 when it is assembled into the housing 200.

[0047] Figure 10 The example shown is the side of the cover plate 300 facing inwards from the housing 200 when it is assembled into the housing 200.

[0048] Embodiments of this application also provide a battery pack 1002, including a secondary battery 100 of any of the above-described embodiments, and the battery pack 1002 may have the beneficial effects described above with respect to the secondary battery 100.

[0049] Embodiments of this application also provide an electronic device 1000, which includes a battery pack 1002 of any of the above-mentioned components, and the electronic device 1000 may have the beneficial effects described above with respect to the secondary battery 100.

[0050] The technical solution provided in this application reduces the thermal impact of welding the cover plate and the manifold on the opening of the housing, and avoids deformation of the opening of the housing.

[0051] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A secondary battery, characterized in that, include: The housing includes a surrounding first sidewall, at least one end of which forms an opening; Electrode assembly, disposed within the housing; A cover plate that covers the opening, the cover plate having an outer periphery welded to the opening and a support portion connected to the outer periphery, the support portion being configured to protrude toward the electrode assembly and having a groove on the outer surface of the support portion away from the electrode assembly; A collector plate is disposed between the cover plate and the electrode assembly; The bottom wall of the groove is welded to the collector plate to form a welded part; the bottom wall has a center line along the radial direction of the shell; in the radial direction, the distance between the welded part and the first side wall is D1, and the distance between the center line and the first side wall is D2, where D1 > D2.

2. The secondary battery according to claim 1, characterized in that, The electrode assembly is a wound component with a central winding hole. The current collector has a weak portion, the projection of which along the axis of the housing at least partially coincides with the central winding hole. The weak portion is configured to tear in the event of thermal runaway of the secondary battery. The collector plate includes a first connecting portion welded to the support portion, and the weak portion is offset toward the cover plate relative to the first connecting portion.

3. The secondary battery according to claim 1, characterized in that, A rounded transition area is provided between at least one second sidewall of the groove and the bottom wall; In the radial direction, the distance between the rounded transition area located radially inside the weld and the weld is W1 mm, where W1 ≥ 0.

1.

4. The secondary battery according to claim 1, characterized in that, In the radial direction, the width of the welded portion is W2mm; the distance between the opposite second sidewalls of the groove in the radial direction is W3mm, wherein 0.13≤W2 / W3≤0.

5.

5. The secondary battery according to claim 1, characterized in that, The cover plate is provided with a plurality of support portions arranged circumferentially around the axis of the housing, and an exhaust channel extending radially along the housing is formed between each pair of adjacent support portions. Wherein, the total length of the bottom wall of each of the support parts extending in the circumferential direction is P1, the plane in which the bottom wall is located is a reference plane, each of the exhaust channels has a cross-section on the reference plane, and the total length of each of the cross-sections extending in the circumferential direction is P2, 0.12≤P2 / P1≤0.

7.

6. The secondary battery according to claim 2, characterized in that, The cover plate is provided with grooves, which are configured to crack to release pressure in the event of thermal runaway of the secondary battery. In the radial direction, the groove is closer to the axis than the support portion.

7. The secondary battery according to claim 6, characterized in that, In the radial direction, the distance between the groove and the support is f mm, where 2 ≤ f ≤ 8.

8. The secondary battery according to any one of claims 1 to 7, characterized in that, The projection of the support part along the axis of the shell is arc-shaped, and the welding part is an arc-shaped weld line.

9. A battery pack, characterized in that, The secondary battery includes any one of claims 1 to 8.

10. An electronic device, characterized in that, Includes the battery pack as described in claim 9.

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