Cylindrical battery, battery pack and electronic device

Abstract

The embodiment of the utility model provides a cylindrical battery, a battery pack and an electronic device, the cylindrical battery comprises: a shell, the end wall of which is provided with a pole mounting hole; the electrode assembly is positioned in the shell; the pole penetrates through the pole mounting hole and is insulated from the end wall, and the first tab and the second tab are electrically connected with the pole and the shell respectively; the sealing nail covers the hole of the pole in a sealing manner and is welded with the pole to form a welding mark; the orthographic projection of the welding mark in the height direction is located outside the pole mounting hole, the sealing nail is provided with a first effective welding area used for being connected with the first connecting part of the busbar in a welded mode, and the maximum diameter of the first effective welding area is smaller than or equal to the maximum diameter of the pole mounting hole. The side, away from the electrode assembly, of the end wall is provided with a second effective welding area used for being in welded connection with the second connecting part of the busbar. According to the technical scheme, at least the reliability of the welding process window of the cylindrical battery and the busbar and the cylindrical battery cell in the battery pack can be improved.

Description

Technical Field

[0001] This utility model relates to the field of batteries, and more specifically, to a cylindrical battery, a battery pack, and an electronic device. Background Technology

[0002] In the field of new energy power batteries, the application of rechargeable batteries is becoming increasingly widespread. These batteries (such as lithium-ion batteries) can be used in vehicles, energy storage, mobile phones, tablets, wearable devices, power banks, e-cigarettes, digital products, power tools, power units, and other electronic devices. One type of rechargeable battery is the cylindrical battery, which includes a casing and electrode assemblies. The electrode assemblies consist of a positive electrode, a first separator, a negative electrode, and a second separator, which are stacked sequentially and wound to form the electrode assembly, which is then encapsulated within the casing. To increase battery capacity, multiple cells are typically connected in series and parallel. Currently, this series-parallel connection of cylindrical batteries is generally achieved by welding a busbar to the cylindrical battery. Therefore, optimizing existing cylindrical batteries and welding processes is a key technical challenge for the further development and overcoming of cylindrical battery cells. Utility Model Content

[0003] In view of the problems existing in the related technologies, the purpose of this utility model is to provide a cylindrical battery, battery pack and electronic device, so as to at least improve the process window for welding cylindrical batteries to busbars and the reliability of cylindrical cells in battery packs.

[0004] To achieve the above objectives, embodiments of this application provide a cylindrical battery comprising: a housing including an end wall and a side wall surrounding the end wall, the end wall having an electrode mounting hole; an electrode assembly located within the housing, the electrode assembly having a first tab and a second tab on opposite sides along the height direction of the cylindrical battery; an electrode post passing through the electrode mounting hole and insulated from the end wall, the first tab and the second tab being electrically connected to the electrode post and the housing respectively, the side of the electrode post opposite to the electrode assembly having a hole recessed toward the electrode assembly; and a sealing pin covering the hole and welded to the electrode post to form a solder mark; wherein the orthographic projection of the solder mark in the height direction of the cylindrical battery is located outside the electrode mounting hole, the sealing pin having a first effective welding area for welding connection with a first connection portion of a busbar, the maximum diameter of the first effective welding area being less than or equal to the maximum diameter of the electrode mounting hole, and the side of the end wall opposite to the electrode assembly having a second effective welding area for welding connection with a second connection portion of the busbar.

[0005] In some embodiments, the minimum area difference x between the projected area of ​​the pole mounting hole along the height direction and the bottom surface area of ​​the hole satisfies: y ≥ 5x - 5mm 2 Where y represents the area corresponding to the maximum diameter of the first effective welding region, and the units of x and y are both mm. 2 .

[0006] In some embodiments, the ratio of the maximum diameter of the first effective welding area to the maximum outer diameter of the housing ranges from 0.2 to 0.5.

[0007] In some embodiments, the cylindrical battery further includes an upper plastic layer disposed on the side of the end wall away from the electrode assembly, and at least a portion of the upper plastic layer is located between the end wall and the electrode post along the height direction; wherein the upper plastic layer includes a main body and a heat-resistant layer covering the main body, and the melting point of the heat-resistant layer is greater than the melting point of the main body.

[0008] In some embodiments, the cylindrical battery further includes a lower plastic layer disposed on the side of the end wall facing the electrode assembly, and the orthographic projection of the second effective welding area along the height direction lies within the area formed by the lower plastic layer.

[0009] In some embodiments, the material of the lower plastic is any one of polypropylene, polyphenylene sulfide, and soluble polytetrafluoroethylene, and the material of the main body of the upper plastic is any one of polypropylene, polyphenylene sulfide, and soluble polytetrafluoroethylene.

[0010] In some embodiments, the lower plastic includes an upper lower plastic layer and a lower lower plastic layer, wherein the upper lower plastic layer is at least partially located between the end wall and the lower lower plastic layer in the height direction of the cylindrical battery.

[0011] In some embodiments, the thickness of the end wall having the second effective welding area ranges from 0.6 mm to 1.2 mm; the aforementioned hole in the pole is a blind hole.

[0012] Embodiments of this application also provide a battery pack comprising any of the cylindrical batteries described above.

[0013] Embodiments of this application also provide an electronic device that includes the battery pack described above.

[0014] The beneficial technical effects of this utility model are as follows:

[0015] A weld mark is formed by welding the sealing pin to the terminal post at the location. The orthogonal projection of the weld mark in the height direction is located outside the terminal post mounting hole, which allows the maximum diameter of the first effective welding area for welding to the busbar to be increased and less than or equal to the maximum diameter of the terminal post mounting hole. This increases the area of ​​the first effective welding area, enlarges the welding window, and optimizes the reliability of welding to the busbar and the reliability of the cylindrical battery in the battery pack. Attached Figure Description

[0016] 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.

[0017] Figure 1 A perspective view of a cylindrical battery according to an embodiment of this application is shown.

[0018] Figure 2 A cross-sectional view of a cylindrical battery according to an embodiment of this application is shown.

[0019] Figure 3 This is a partially enlarged schematic diagram of the terminal of a cylindrical battery according to some embodiments.

[0020] Figure 4 This is a partially enlarged schematic diagram of the terminal of a cylindrical battery according to some embodiments.

[0021] Figure 5 This is a partially enlarged schematic diagram of the second effective welding area where the end wall is welded to the busbar according to some embodiments.

[0022] Figure 6 A schematic diagram is shown when the electronic device according to an embodiment of this application is a vehicle. Detailed Implementation

[0023] To better understand the spirit of the embodiments of this application, the following description is based on some preferred embodiments of this application.

[0024] 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.

[0025] As used herein, the terms “approximately,” “substantially,” “substantially,” and “about” are used to describe and indicate minor variations. When used in conjunction with an event or situation, the 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.

[0026] 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.

[0027] 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.

[0028] Cylindrical batteries (such as 46mm diameter cylindrical batteries) have emerged in recent years. Cylindrical batteries (also known as cells) combined with CTC (Cell to Chassis) technology can significantly improve the energy density of the entire battery pack. Because CTC technology requires a steel casing for cylindrical batteries, resulting in a relatively large overall structural weight, 46mm series large cylindrical batteries often require high-energy-density positive and negative electrode materials to increase energy density. In this context, improving the safety performance of cylindrical batteries is particularly important. CTC structural design is especially crucial for the electrical connections of cylindrical batteries; optimizing the busbar welding interface and its efficiency is paramount in existing cylindrical battery designs.

[0029] Figure 1 A perspective view of a cylindrical battery 100 according to some embodiments is shown. Figure 2 A cross-sectional view of a cylindrical battery 100 according to an embodiment of this application is shown. (In conjunction with...) Figures 1 to 2As shown, the cylindrical battery 100 includes a casing, which comprises a housing 200 and a cover plate 220. Specifically, the housing 200 includes a peripheral sidewall 109 and an end wall 111 connected to one end of the peripheral sidewall 109. An opening 205 is provided at the other end of the peripheral sidewall 109 opposite to the end wall 111, and the cover plate 220 covers the opening 205 of the housing 200. The cover plate 220 can be used to encapsulate the electrode assembly 120 and the electrolyte together with the housing 200. The material of the housing 200 can be any of a variety of available materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. The housing 200 can be cylindrical and define a receiving cavity in which the electrode assembly 120 is disposed. The outer diameter of the housing 200 can be determined according to the specific diameter of the electrode assembly 120; for example, the outer diameter of the housing 200 can be, for example, 18 mm, 21 mm, 46 mm, etc. In some embodiments, the cylindrical battery 100 may be a 4680 cylindrical battery (outer diameter 46mm, height 80mm), or a 4695 cylindrical battery (outer diameter 46mm, height 95mm), or a 46120 cylindrical battery (outer diameter 46mm, height 120mm).

[0030] The electrode assembly 120 can be formed primarily by sequentially stacking and winding a positive electrode sheet, a negative electrode sheet, and a separator located between the positive and negative electrode sheets. The positive electrode sheet, negative electrode sheet, and separator can be wound around an axis Lc. Furthermore, the electrode assembly 120 also has a winding center hole 120c, and the axis Lc can be the axis of the winding center hole 120c. The wound electrode assembly 120 can have a winding center hole 120c. In some embodiments, the positive electrode sheet may include a positive current collector and a positive active material layer, the positive active material layer being coated on a portion of the surface of the positive current collector. The uncoated area of ​​the positive current collector not covered by the positive electrode coating area is used to form a positive electrode tab 125. The negative electrode sheet may include a negative current collector and a negative active material layer, the negative active material layer being coated on a portion of the surface of the negative current collector. The uncoated area of ​​the negative current collector not covered by the negative electrode coating area is used to form a negative electrode tab 124.

[0031] In some embodiments, 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 can include a positive electrode active material, such as lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. For high-nickel ternary lithium batteries, the positive electrode active material can be a ternary material composed of nickel, cobalt, and manganese (or aluminum), with a relatively high nickel content, typically above 60%. Similarly, the negative electrode can include a negative electrode current collector and a negative electrode active material layer coated on both sides of the negative electrode current collector. The portion of the negative electrode current collector not coated with the negative electrode active material layer constitutes the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material layer can include a negative electrode active material, such as carbon or silicon.

[0032] An inwardly protruding groove 113 (also referred to as a crimping portion) is formed on the peripheral sidewall of the housing 200 near the opening 205. An electrode assembly 120 is disposed between the end wall 111 and the groove 113, and the groove 113 restricts the movement of the electrode assembly 120 in the Z direction and its opposite direction between the end wall 111 and the groove 113. The direction from the opening 205 to the end wall 111 is the axial direction of the electrode assembly 120 and the height direction Z of the cylindrical battery. The end of the peripheral sidewall 109 of the housing 200 on the opening 205 side can be configured as a rolled edge 32, which extends radially inward into the housing 200, perpendicular to the Z direction. The rolled edge 32 and the groove 113 are spaced apart in the Z direction, and the groove 113 and the rolled edge 32 can together clamp the cover plate 220. The cover plate 220 can be electrically insulated from the housing 200.

[0033] The cover plate 220 may have a weak part. When the battery experiences thermal runaway, the high-temperature and high-pressure emissions inside can be discharged to the outside through the weak part on the cover plate 220 after breaking through the bottom of the battery, thereby achieving good discharge of the emissions.

[0034] The negative electrode tab 124 of the electrode assembly 120 faces the opening 205 and can be electrically connected to the housing 200 via a negative electrode current collector 201 located between the cover plate 220 and the electrode assembly 120, thereby making the housing 200 negatively charged. The negative electrode current collector 201 can be welded to the housing 200 by laser welding. Specifically, the welding position of the negative electrode current collector 201 to the housing 200 is located on the side of the groove 113 facing the electrode assembly 120.

[0035] The cylindrical battery 100 may further include a terminal post 160 that passes through and is insulated from the end wall 111. The terminal post 160 can be electrically connected to the positive electrode tab 125 of the electrode assembly 120 via a positive current collector 202 located between the terminal post 160 and the electrode assembly 120, thereby making the terminal post 160 positively charged. In some embodiments, the terminal post 160 can be welded to the positive current collector 202 by laser penetration welding.

[0036] In one example of the cylindrical battery 100 of the present invention, the method for manufacturing the cylindrical battery 100 of the present invention includes the following steps:

[0037] Winding: A winding structure formed by stacking and winding negative electrode sheet, separator and positive electrode sheet, the uncoated part of the negative current collector of negative electrode sheet and the positive current collector of positive electrode sheet is used as positive electrode tab 125 and negative electrode tab 124, and the positive electrode tab 125 and negative electrode tab 124 are bent along the radial direction of electrode assembly 120.

[0038] Welding of current collectors to electrode assemblies: The positive current collector 202 and the negative current collector 201 are welded to the surface areas of the bent positive electrode tab 125 and the negative electrode tab 124, respectively.

[0039] Installation into the housing: The electrode assembly 120, which has been welded to the negative current collector 201 and the positive current collector 202, is installed into the housing 200 through the opening 205. The method of installing the electrode assembly 120 in this step is not limited. For example, it can be installed manually or by a robot.

[0040] Install pole 160.

[0041] Electrolyte injection: The method of electrolyte injection is not limited, and injection can be carried out through opening 205. In this embodiment, electrolyte is injected through opening 205, which reduces the step of opening an injection hole in the end wall 111. The existing opening 205 can be used directly for injection, simplifying the process and reducing costs.

[0042] Sealing: The cover plate 220 is sealed and installed on the opening 205. There are various sealing methods, and this is not limited to one. In some embodiments, a rolling groove 113 recessed towards the center of the housing 200 is first formed on the outer periphery of the housing 200 to restrict the movement of the electrode assembly 120 in the Z direction. Then, a mechanical sealing process is used to press and seal the cover plate 220 to form a rolled edge 32, thereby sealing and installing the cover plate 220 on the opening 205 of the housing 200. This step is a mature process, low in cost, and highly efficient.

[0043] The current design of cylindrical battery terminals typically employs a riveted structure, assembling the terminal, upper plastic casing, lower plastic casing, and a housing with terminal mounting holes. During busbar welding, the terminal and housing are the primary welding points, but the welding window is relatively small, significantly impacting cell reliability. Therefore, it is necessary to optimize the cylindrical battery structure and welding process.

[0044] Figure 3 This is a partially enlarged schematic diagram of the terminals of a cylindrical battery according to some embodiments. See also Figure 3As shown, the end wall 111 of the housing 200 has a pole mounting hole 108. A pole 160 passes through the pole mounting hole 108 and is insulated from the end wall 111. The pole 160 has a hole 117 recessed towards the electrode assembly on the side opposite to the electrode assembly. A sealing pin 211 covers the hole 117 and is welded to the pole 160 to form a solder mark at position 502. In some embodiments, such as Figure 3 As shown, hole 117 is a blind hole.

[0045] exist Figure 3 In this configuration, the electrode post 160 and sealing pin 211 are used for welding to the first connection portion (e.g., the positive electrode connection portion) of the busbar. The first effective welding area for welding to the busbar is located on the side of the electrode post 160 and sealing pin 211 facing away from the electrode assembly. The first effective welding area may have a circular shape, and the maximum diameter of the first effective welding area is d'. The maximum diameter d' of the first effective welding area is consistent with the diameter of the portion of the electrode post passing through the electrode post mounting hole 108 (the difference between the two is within the range of manufacturing tolerances).

[0046] Figure 4 This is a partially enlarged schematic diagram of the terminals of a cylindrical battery according to some embodiments. See also Figure 4 As shown, the terminal post 160 passes through the terminal post mounting hole 108 of the end wall 111. The terminal post 160 is insulated from the end wall 111 by the lower plastic 60 and the upper plastic 70, respectively, and the terminal post mounting hole 108 is sealed by the sealing element 90. The terminal post 160 can be assembled with the housing by riveting. In the height direction Z of the cylindrical battery, the upper plastic 70 is at least partially clamped between the outer flange of the terminal post 160 and the end wall 111, and the lower plastic 60 is at least partially clamped between the inner flange of the terminal post 160 and the end wall 111.

[0047] The lower plastic 60 is disposed on the side of the end wall 111 facing the electrode assembly and can extend into the post mounting hole 108, thereby isolating the post 160 from the side of the end wall 111 facing the electrode assembly. The upper plastic 70 is disposed on the side of the end wall 111 away from the electrode assembly, thereby isolating the post 160 from the side of the end wall 111 away from the electrode assembly.

[0048] exist Figure 4 In the illustrated embodiment, a sealing pin 211 covers the hole 117, and the sealing pin 211 is welded to the electrode post 160 at position 502 to form a weld mark. The orthogonal projection of the weld mark in the height direction Z lies outside the electrode post mounting hole 108. In this embodiment, the sealing pin has a first effective welding area 901 for welding connection with the first connection portion (positive electrode connection portion) of the busbar. The maximum diameter d1 of the first effective welding area 901 is less than or equal to the maximum diameter of the electrode post mounting hole 108 (the difference between the two is within the range of process tolerance). Figure 4The figure shows that the maximum diameter d1 is equal to the maximum diameter of the pole mounting hole 108, as an example.

[0049] On the other hand, the side of the end wall 111 facing away from the electrode assembly has a second effective welding area for welding connection with the second connection portion (negative electrode connection portion) of the busbar. In this way, the positive terminal (terminal) and negative terminal (casing) of the cylindrical battery are connected to the positive and negative electrode connection portions of the busbar, respectively.

[0050] The above-described technical solution of this application forms a weld mark by welding the sealing pin 211 to the terminal post 160 at position 502. The orthogonal projection of the weld mark in the height direction Z is located outside the terminal post mounting hole 108, which avoids the welding area of ​​the first effective welding area 901 being too small. If the welding area is too small, it will affect the welding of the busbar, resulting in a low process window and compromised welding efficiency. The weld mark being located outside the terminal post mounting hole 108 allows the maximum diameter d1 of the first effective welding area 901 used for welding with the busbar to be increased and made smaller than or equal to the maximum diameter of the terminal post mounting hole 108. This increases the area of ​​the first effective welding area, enlarges the welding window, and optimizes the reliability of welding with the busbar and the reliability of the cylindrical battery in the battery pack.

[0051] The ratio of d1 to the maximum outer diameter of the housing ranges from 0.2 to 0.5. Since d1 is increased to match the maximum diameter of the pole mounting hole 108, the proportion of d1 to the maximum outer diameter of the housing can be increased to a range of 0.2-0.5. This increases the welding window and optimizes the reliability of welding to the busbar.

[0052] In some embodiments, the first effective welding area 901 includes multiple weld lines, the trajectory shape of which is typically spiral or linear. A spiral shape is preferred to avoid insufficient area for dotted weld lines. The area of ​​the weld in the first effective welding area 901 is related to the current requirement of the battery cell, and the relationship between the minimum effective welding area of ​​the first effective welding area 901 and the current requirement should satisfy the following formula: Y = 8X - 5mm 2 Where X is the minimum effective welding area of ​​the first effective welding zone, and Y is the overcurrent requirement. The units of X and Y are both mm. 2 .

[0053] Furthermore, it is typically necessary to design the diameter difference dc between the maximum diameter d1 of the first effective welding area 901 and the bottom diameter dn of the hole 117 to meet the actual current carrying capacity requirements of the battery. The minimum area difference x between the annular area formed by dc and the projected area of ​​the terminal mounting hole 118 along the height direction Z and the bottom area of ​​the hole 117 should satisfy: y ≥ 5x - 5mm 2 y represents the area corresponding to the maximum diameter d1 of the first effective welding area 901, and the units of x and y are both mm.2 In other words, the area of ​​the annulus formed by dc cannot be less than x determined by this relationship. In some embodiments, y can be calculated using the following formula: y = 3.14 × (d1 / 2) 2 .

[0054] In some embodiments, the electrode post 160 is made of aluminum, such as 1-series or 3-series aluminum, preferably 1-series aluminum. The upper plastic 70 can be made of any one of PP (polypropylene), PPS, or PFA, preferably PFA. In some embodiments, the upper plastic 70 may include a main body and a heat-resistant layer covering the main body. The melting point of the heat-resistant layer is higher than that of the main body. The material of the heat-resistant layer is a material with a melting point higher than that of the main body. By coating the upper plastic with a heat-resistant layer, heat resistance can be improved, damage to the upper plastic due to welding fluctuations can be avoided, welding reliability can be improved, and the airtightness and insulation of the battery can be ensured. In some preferred embodiments, the material of the heat-resistant layer can be polytetrafluoroethylene (PTFE), and the material of the main body can be PP (polypropylene). This is because PP is inexpensive, reducing costs, and PTFE provides excellent sealing and heat resistance. In other embodiments, the material of the main body can be any one of PPS (polyphenylene sulfide) or PFA (soluble polytetrafluoroethylene). The heat-resistant coating material can be PI (polyimide) or Al2O3. In some embodiments, the thickness of the heat-resistant layer can be 2μm-5μm, preferably 5μm, and the heat-resistant layer material can achieve insulation and heat resistance for the upper plastic. From a cost perspective, the heat-resistant layer material is preferably Al2O3.

[0055] Figure 5 This is a partially enlarged schematic diagram of the second effective welding area at the end wall and busbar welding according to some embodiments. (Reference) Figure 5 As shown, the end wall 111 has a second effective welding area 902 for welding to the second connection portion (negative electrode connection portion) of the busbar. The orthographic projection of the second effective welding area 902 along the height direction Z lies within the area formed by the lower plastic 60. That is, the entire area of ​​the second effective welding area 902 is located above the lower plastic 60, and it is not permissible for the lower plastic 60 not to be provided below the second effective welding area 902, so as to isolate the welding heat from affecting the internal components of the housing through the lower plastic 60.

[0056] The thickness of the housing 200 can range from 0.6 mm to 1.2 mm, so that the thickness of the end wall 111, where the second effective welding area 902 is provided, also ranges from 0.6 mm to 1.2 mm. The thickness of the end wall 111 is preferably 0.7 mm. The material of the housing 200 can be SPCC steel / SPCE steel or stainless steel, preferably SPCC steel. The outer surface of the housing 200 is typically covered with a 2 μm-5 μm (preferably 3 μm) nickel plating layer to ensure the reliability of external welding.

[0057] In some embodiments, the material of the lower plastic layer 60 can be any of PP, PPS, and PFA, preferably PFA. In some embodiments, the lower plastic layer 60 can be a two-piece design. Specifically, the lower plastic layer 60 includes an upper lower plastic layer 61 and a lower lower plastic layer 62. The upper lower plastic layer 61 is at least partially located between the end wall 111 and the lower lower plastic layer 62 in the height direction Z. The two-piece design can reduce costs while ensuring that it is not affected by the heat of the second effective welding area 902. The upper lower plastic layer 61 needs to provide insulation and heat resistance, and is usually preferably made of PFA, which has good heat resistance among PP, PPS, and PFA, or PP material with a PI / Al2O3 coating (i.e., a heat-resistant layer). The material of the lower lower plastic layer 62 can be any of PP, PPS, and PFA, preferably PP material with lower cost. The above design of the upper plastic layer 61 and the lower plastic layer 62 can improve heat resistance, avoid damage to the lower plastic layer 60 due to welding fluctuations, improve welding reliability, and ensure that the battery's airtightness and insulation are not compromised.

[0058] See Figure 6This application also provides an electronic device 1000. For ease of explanation, the following embodiments use a vehicle as an example. A battery pack 1002 is installed inside the vehicle. The battery pack 1002 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. The working part of the electronic device 1000 is electrically connected to the battery pack 1002 to obtain electrical power. The vehicle 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 movement 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, power tool, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; the working unit can obtain electrical energy from the battery pack 1002 and perform corresponding work, such as the fan blade rotation unit of a fan, the vacuuming unit of a vacuum cleaner, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship 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 embodiment does not impose special limitations on the above-described electronic device 1000. The battery pack 1002 may include multiple of the above-described secondary batteries, such as cylindrical batteries.

[0059] 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 cylindrical battery, characterized in that, include: The housing includes an end wall and a side wall surrounding the end wall, the end wall having a pole mounting hole; An electrode assembly is located inside the housing, and the electrode assembly has a first tab and a second tab on opposite sides along the height direction of the cylindrical battery, respectively. The electrode post passes through the electrode post mounting hole and is insulated from the end wall. The first electrode tab and the second electrode tab are electrically connected to the electrode post and the housing, respectively. The side of the electrode post facing away from the electrode assembly has a hole recessed towards the electrode assembly. A sealing pin is placed over the hole and welded to the pole post to form a weld mark; Wherein, the orthographic projection of the solder mark in the height direction of the cylindrical battery is located outside the terminal mounting hole, and the sealing pin has a first effective welding area for welding connection with the busbar, the maximum diameter of the first effective welding area being less than or equal to the maximum diameter of the terminal mounting hole. The side of the end wall opposite to the electrode assembly has a second effective welding area for welding connection with the second connection portion of the busbar.

2. The cylindrical battery according to claim 1, characterized in that, The minimum area difference x between the projected area of ​​the pole mounting hole along the height direction and the bottom area of ​​the hole satisfies: y ≥ 5x - 5mm 2 Where y represents the area corresponding to the maximum diameter of the first effective welding region, and the units of x and y are both mm. 2 .

3. The cylindrical battery according to claim 1, characterized in that, The ratio of the maximum diameter of the first effective welding area to the maximum outer diameter of the shell is in the range of 0.2-0.

5.

4. The cylindrical battery according to claim 1, characterized in that, Also includes: An upper plastic is disposed on the side of the end wall opposite to the electrode assembly, and at least a portion of the upper plastic is located between the end wall and the electrode post along the height direction; The upper plastic includes a main body and a heat-resistant layer covering the main body, wherein the melting point of the heat-resistant layer is greater than the melting point of the main body.

5. The cylindrical battery according to claim 4, characterized in that, Also includes: The lower plastic is disposed on the side of the end wall facing the electrode assembly, and the orthographic projection of the second effective welding area along the height direction lies within the area formed by the lower plastic.

6. The cylindrical battery according to claim 5, characterized in that, The material of the lower plastic is any one of polypropylene, polyphenylene sulfide, and soluble polytetrafluoroethylene. The material of the main body of the upper plastic is any one of polypropylene, polyphenylene sulfide, and soluble polytetrafluoroethylene.

7. The cylindrical battery according to claim 5, characterized in that, The lower plastic includes an upper lower plastic layer and a lower lower plastic layer, wherein the upper lower plastic layer is at least partially located between the end wall and the lower lower plastic layer in the height direction of the cylindrical battery.

8. The cylindrical battery according to claim 1, characterized in that, The thickness of the end wall where the second effective welding area is provided ranges from 0.6 mm to 1.2 mm; The hole is a blind hole.

9. A battery pack, characterized in that, The cylindrical 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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