Cylindrical battery and electronic device

Abstract

The present application relates to a cylindrical battery and an electronic device. The cylindrical battery comprises a housing and an electrode assembly. In the axial direction of the electrode assembly, the housing is provided with a first end portion, the electrode assembly is arranged within the housing, the first end portion is provided with a first surface facing away from the electrode assembly, and the first surface is provided with at least one soldering position. The cylindrical battery further comprises a protective piece. The protective piece is arranged on the housing and covers part of the first surface, and at least part of the soldering position is exposed on the protective piece. The protective piece is arranged on the housing and covers part of the first surface, so as to partially protect the first surface, and at least part of the soldering position is exposed on the protective piece, so as to reduce the interference of the soldering position on the protective piece, and reduce the increase in length of the cylindrical battery caused by the protective piece covering the soldering position, which not only improves the ease of mounting the cylindrical battery on the electronic device, but also increases the energy density of the cylindrical battery.

Description

Cylindrical battery and electronic device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application No. 202410895136.7, filed on July 04, 2024, and entitled “Cylindrical battery and electronic device”, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of battery, in particular to a cylindrical battery and an electronic device. BACKGROUND

[0004] In the cylindrical battery, laser penetration welding is usually needed to be performed on the bottom of the shell of the cylindrical battery, so as to electrically connect the shell and the internal electrode assembly. However, the laser penetration welding will leave a welding site on the bottom of the shell. When the heat shrink film is wrapped on the cylindrical battery, the heat shrink film is prone to interfere with the welding site, and the heat shrink film is prone to be stacked with the welding site, which will cause the size of the cylindrical battery to increase, which is not conducive to the installation of the cylindrical battery on the electronic device, and also affects the energy density of the cylindrical battery. SUMMARY

[0005] The purpose of the present application is to provide a cylindrical battery and an electronic device, which aims to solve the technical problem that the welding site interferes with the protective member and affects the energy density of the cylindrical battery.

[0006] According to a first aspect of the present application, a cylindrical battery is provided, comprising a shell and an electrode assembly. Along the axial direction of the electrode assembly, the shell has a first end portion, and the electrode assembly is arranged in the shell. The first end portion has a first surface facing away from the electrode assembly, and the first surface is provided with at least one welding site. The cylindrical battery further comprises a protective member arranged on the shell and covering part of the first surface, and at least part of the welding site is exposed to the protective member.

[0007] In the above technical solution, the protective member is arranged on the shell and covers part of the first surface, which can partially protect the first surface. At least part of the welding site is exposed to the protective member, which can reduce the interference of the welding site with the protective member and reduce the increase in the length size of the cylindrical battery caused by the protective member covering the welding site. Not only can the installation convenience of the cylindrical battery on the electronic device be improved, but also the energy density of the cylindrical battery can be improved.

[0008] In some preferred embodiments, the minimum distance between the center of the first surface and the outer periphery of the first end is R, the distance between the welding site and the center of the first surface is L, and 0.5R≤L≤0.95R. Defining L≥0.5R allows the welding site to be arranged away from the center of the first surface, which can reduce the interference of the welding site with the probe and facilitate the testing of the probe. Moreover, arranging the welding site away from the center of the first surface can prevent the probe from sliding off the first surface, thereby facilitating the formation voltage test, and reducing the interference of the protective member with the busbar connection. Defining L≤0.95R can reduce the influence of the chamfer on welding, and reduce the problems of virtual welding and insufficient welding tension caused by the chamfer.

[0009] In some preferred embodiments, the protective member covers part of the welding site, the distance between the inner edge of the welding site and the center of the first surface is L1, the distance between the outer edge of the welding site and the center of the first surface is L2, the distance between the inner edge of the protective member and the center of the first surface is L3, and 0

[0010] In some preferred embodiments, the welding site is arc-shaped, which can facilitate the increase of the coverage area of the protective member on the welding site, reduce the corrosion of the welding site, and reduce the overlap between the protective member and the highest part of the center of the welding site.

[0011] In some preferred embodiments, the protective member does not cover the welding site, and the distance between the inner edge of the protective member and the outer edge of the welding site is L4, which satisfies 0≤L4≤0.5R. This allows the welding site to have sufficient distance from the center of the first surface for welding connection with external circuits and facilitates the contact test of the probe. In some embodiments, the shape of the welding site can be arc-shaped, trapezoidal, wavy, irregular, etc. as viewed along the axial direction of the battery.

[0012] In some preferred embodiments, 0≤L4≤0.2R, which further improves the convenience of welding the first surface with external circuits and the convenience of contacting the first surface with the probe.

[0013] In some preferred embodiments, the outer surface of the welding site is further provided with a protective layer, which can reduce the erosion of the welding site by external water vapor, dust, etc. and reduce the rusting of the welding site.

[0014] In some preferred embodiments, in the RFU mode of the fluorescence detector, the fluorescence intensity of the protective layer at the welding site is Q, and 5≤Q≤600, which can reduce the rusting of the welding site while facilitating the welding connection of the first surface with external circuits and improving the connection strength.

[0015] In some preferred embodiments, the sum of the projected areas of all the welding sites on the first surface is S, 0.2mm 2 ≤S≤0.8mm 2 Not only the overcurrent temperature rise requirement of the cylindrical battery is met, but also the welding strength requirement is met, and meanwhile the interference with the external circuit welding and the probe can be reduced.

[0016] In some preferred embodiments, at least two welding sites are arranged around the center of the first surface. By arranging the welding sites around the first end portion, the contact area of the welding can be increased, and the strength and stability of the welding can be improved. The cylindrical battery can better withstand the vibration and impact during use, and the risk of cracks or looseness at the welding site can be reduced. Moreover, the welding site is arranged around, which can make the current more uniformly distributed at the first end portion, which helps to reduce the current concentration in a local area and reduce the resistance and heat generation.

[0017] In some preferred embodiments, at least one welding site is arranged at least one circle around the center of the first surface. Such a structure can also improve the welding strength. Moreover, when one welding site is used, the welding operation can be continuous without interruption, and the welding efficiency can be improved.

[0018] In some preferred embodiments, a current collecting plate is further included, the current collecting plate is arranged in the shell and electrically connected between the electrode assembly and the first end portion, and the welding site is configured to be welded to the current collecting plate. The welding site extends from the first surface to the current collecting plate, and the welding site includes a first portion located at the current collecting plate. In the direction from the first end portion to the current collecting plate, the thickness of the first portion is T1, and the thickness of the current collecting plate is T2, 2μm≤T1

[0019] In a second aspect, the application further provides an electronic device, which comprises the cylindrical battery according to any one of the embodiments of the first aspect.

[0020] Additional aspects and advantages of the embodiments will be described in part in the description that follows, and will be shown in part by the description of the embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0021] One or more embodiments are illustrated by way of example in the accompanying drawings, which are not necessarily drawn to scale, and which, if simple, are not limiting of the embodiments. Identical reference numbers in different drawings identify similar elements.

[0022] FIG. 1 is an exploded view of a cylindrical battery according to some embodiments of the application;

[0023] FIG. 2 is a full cross-sectional view of a shell according to some embodiments of the application;

[0024] Fig. 3 is a full cross-sectional view of a cylindrical battery according to some embodiments of the present application;

[0025] Fig. 4 is a structural schematic view of a first end portion according to some embodiments of the present application;

[0026] Fig. 5 is a structural schematic view of a cylindrical battery according to some embodiments of the present application;

[0027] Fig. 6 is a structural schematic view of a first end portion according to some embodiments of the present application;

[0028] Fig. 7 is a structural schematic view of a first end portion according to some embodiments of the present application;

[0029] Fig. 8 is a structural schematic view of a first end portion according to some embodiments of the present application;

[0030] Fig. 9 is a structural schematic view of a first end portion according to some embodiments of the present application;

[0031] Fig. 10 is a structural schematic view of a first end portion according to some embodiments of the present application;

[0032] Fig. 11 is an exploded view of a cylindrical battery according to some embodiments of the present application;

[0033] Fig. 12 is a full cross-sectional view of a cylindrical battery according to some embodiments of the present application;

[0034] Fig. 13 is a full cross-sectional view of a first end portion according to some embodiments of the present application.

[0035] BRIEF DESCRIPTION OF DRAWINGS DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions, and advantages of the embodiments of the present application clearer, the following will be used to clearly describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application.

[0037] Reference to "an embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another.

[0038] In the description of the embodiments of the present application, the technical terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified.

[0039] In the description of the embodiments of the present application, the term "and / or" is only used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are in an "or" relationship.

[0040] The technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict between them.

[0041] In a first aspect, the present application proposes a cylindrical battery 100, please refer to FIG. 1, the cylindrical battery 100 includes a shell 10, an electrode assembly 20 and a protective piece 30, the electrode assembly 20 is arranged in the shell 10 to perform electrochemical reaction in the shell 10, and the protective piece 30 is arranged outside the shell 10 to protect the shell 10.

[0042] For the above-mentioned shell 10, the shell 10 is used to accommodate the above-mentioned electrode assembly 20 and electrolyte, the electrolyte infiltrates the electrode assembly 20 in the shell 10, so that electrochemical reaction occurs. Please refer to FIG. 1 and FIG. 2, the shell 10 can adopt a columnar shape, the shell 10 includes a main body part 11, a first end part 12 and a second end part 13, along the axial direction X of the shell 10, the first end part 12 and the second end part 13 are respectively located at both ends of the shell 10. Optionally, the main body part 11 can adopt the form of two open ends 111, the electrode assembly 20 can be directly put into the main body part 11 through the open end 111, and then the open end 111 is sealed through the first end part 12 and the second end part 13 to form a complete shell 10. In some other embodiments, the main body part 11 can also adopt the form of one end being sealed and the other end being open 111, that is, the first end part 12 or the second end part 13 is integrally formed and arranged with the main body part 11. In some other embodiments, the first end part 12 and the second end part 13 can also be arranged separately with the main body part 11, that is, they are independent of each other before assembly, and then the first end part 12 and the second end part 13 are connected with the main body part 11 by welding or gluing.

[0043] In the embodiments of the present application, the shell 10 can be formed by punching a metal sheet, and the thickness of the metal sheet can be set to 0.1-0.4 mm to improve the punching strength of the shell 10. The metal sheet can be made of conductive metal materials such as aluminum, steel, stainless steel, nickel, copper, or magnesium alloy, so that the shell 10 can lead out a certain polarity of the cylindrical battery 100, for example, the shell 10 itself can be used as the positive or negative electrode of the cylindrical battery 100.

[0044] For the electrode assembly 20, the electrode assembly 20 includes a first electrode tab (not shown in the figure), a separator (not shown in the figure), and a second electrode tab (not shown in the figure), and the separator, the first electrode tab, the separator, and the second electrode tab are sequentially stacked and wound to form a cylindrical wound electrode assembly 20. The polarities of the first electrode tab and the second electrode tab are opposite, and the separator is arranged between the first electrode tab and the second electrode tab to insulate and separate them. Referring to FIG. 3, the electrode assembly 20 is adapted to the shell 10, and the electrode assembly 20 is accommodated in the shell 10. In other embodiments, the first electrode tab, the separator, the second electrode tab, and the separator are sequentially stacked and wound to form a cylindrical wound electrode assembly 20.

[0045] Optionally, the negative electrode of the electrode assembly 20 is electrically connected to the first end portion 12 of the shell 10, and the positive electrode of the electrode assembly 20 is electrically connected to the second end portion 13.

[0046] For example, the negative electrode tab of the electrode assembly 20 is connected to a plurality of negative electrode tabs (not shown in the figure) or an empty foil area (not shown in the figure) without a material layer, the negative electrode tabs face the first end portion 12, and the negative electrode tabs or the empty foil area are flattened to form a negative electrode flattened surface. The first end portion 12 is directly electrically connected to the negative electrode flattened surface by penetration welding, and then the negative electrode is led out through the first end portion 12.

[0047] The positive electrode of the electrode assembly 20 can also be similarly arranged, and the positive electrode tabs or the empty foil area (not shown in the figure) without a material layer of the positive electrode tab are flattened to form a positive electrode flattened surface, and the second end portion 13 is electrically connected to the positive electrode flattened surface to lead out the positive electrode through the second end portion 13. Alternatively, the second end portion 13 is in the form of a pole 131, and the pole 131 is electrically connected to the positive electrode flattened surface. Since the polarities of the second end portion 13 and the first end portion 12 are opposite, the second end portion 13 and the main body portion 11 can be connected in an insulating manner, for example, an insulating member is arranged between the second end portion 13 and the main body portion 11.

[0048] In other embodiments, the first end portion 12 can lead out the positive electrode, and the second end portion 13 can lead out the negative electrode, which is not limited in the present application.

[0049] Referring to FIG. 3, the protective member 30 is sleeved outside the shell 10 and extends partially to the outer surface of the first end portion 12. The protective member 30 can effectively prevent moisture and humidity from entering the cylindrical battery 100, thereby protecting the chemical materials of the cylindrical battery 100 from being dampened and maintaining the stability of the battery performance. In addition, the protective member 30 provides a certain degree of physical protection for the cylindrical battery 100, thereby reducing the damage caused by external mechanical forces such as collision and extrusion to the cylindrical battery 100. The relevant information of the cylindrical battery 100, such as brand, model, and parameters, can also be printed on the protective member 30, which facilitates identification and management and makes the cylindrical battery 100 more neat and beautiful in appearance.

[0050] In some embodiments, the protective member 30 can be a heat-shrinkable film. After the heat-shrinkable film is sleeved outside the shell 10, the heat-shrinkable film can be tightly attached to the outer surface of the shell 10 by heating. In other embodiments, the protective member 30 can also be a plastic shell (such as a hard plastic shell made of polycarbonate, polypropylene, etc.), an insulating tape (such as a polyester film tape, a polyimide tape, etc.), and a composite film (such as a composite film of polyethylene terephthalate (PET) and aluminum foil), etc.

[0051] Referring to FIGS. 3 and 4, the first end portion 12 has a first surface 121 facing away from the electrode assembly 20, which is used for conduction with an external circuit. The first end portion 12 can be electrically connected to the electrode assembly 20 by penetration welding, which forms at least one welding site 122 on the outer surface of the first end portion 12. In the embodiments of the present application, the protective member 30 is arranged on the shell 10 and covers part of the first surface 121, thereby partially protecting the first surface 121. At least part of the welding site 122 is exposed to the protective member 30, which can reduce the interference of the welding site 122 with the protective member 30 and reduce the increase in the length of the cylindrical battery 100 caused by the protective member 30 covering the welding site 122. This not only facilitates the installation of the cylindrical battery 100 on electronic devices, but also improves the energy density of the cylindrical battery 100.

[0052] And, when the cylindrical battery 100 is undergoing formation or voltage test, the uncovered portion of the welding site 122 can limit the probe, which can effectively reduce the probe from falling off the first surface 121. While the protector 30 itself is soft, when the probe contacts the first surface 121, the slight extrusion of the probe to the edge of the protector 30 can cause the edge of the protector 30 to deform, and the probe is also prone to slide from the first surface 121 to the outer surface of the protector 30. While the protector 30 is made of insulating material, this can directly cause the probe to be disconnected from the contact test of the first surface during formation or voltage test, affecting the test efficiency. Compared with limiting the probe through the protector 30, the uncovered portion of the welding site 112 is used to limit the probe in the present application, and the welding site 112 has higher strength and can conduct electricity, which can facilitate the smooth progress of the formation or voltage test.

[0053] In the above, the welding site 122 can be a welding point, a welding line, or a combination of a welding point and a welding line.

[0054] In some embodiments, referring to FIG. 4, the welding site 122 is arranged away from the center of the first surface 121, the minimum distance between the center of the first surface 121 and the outer periphery of the first end 12 is R, the distance between the center of the welding site 122 and the center of the first surface 121 is L, and 0.5R≤L≤0.95R. When a single welding site 122 is only a welding line with a relatively narrow width, the distance between the center of the welding line and the center of the first surface is L. It can be understood that the highest point of the welding site 122 is usually located at the center of the welding site 122, and by limiting the center of the welding site 122 to 0.5R≤L≤0.95R, the interference of the highest point of the welding site 122 to the probe can be reduced. It should be noted that the center of the welding site 122 can be the center in the length direction and / or the center in the width direction of the welding site 122.

[0055] In some embodiments, when there are multiple welding lines, and the multiple welding lines are arranged in sequence from the center to the outer periphery, or the multiple welding lines are arranged around the center of the first surface 121, the minimum distance between the center of the welding site 122 (i.e., a certain welding line) and the center of the first surface 121 is greater than 0.5R, and the maximum distance between the center of the welding site 122 (i.e., another welding line) and the center of the first surface 121 is less than 0.95R. In other embodiments, all welding sites 122 can also be directly limited within the range of 0.5R to 0.95R, that is, the highest point of the center of the welding site 122 is located within the range of 0.5R to 0.95R.

[0056] In the embodiments of the present application, L≥0.5R is defined so that the welding sites 122 are arranged away from the center of the first surface 121. The center of the first surface 121 is free of the welding sites 122, and when the cylindrical battery 100 is subjected to formation or voltage testing, the probe can be used to perform contact testing on the first end portion 12 at the center of the first surface 121, which can reduce the interference of the welding sites 122 or the highest welding sites 122 on the probe and facilitate the testing of the probe. Moreover, the welding sites 122 or the highest welding sites 122 are arranged away from the center of the first surface 121, which can prevent the probe from sliding off the first surface 121 and facilitate the formation or voltage testing.

[0057] Furthermore, when the cylindrical battery 100 is electrically connected to an external circuit, for example, is welded to a bus bar (not shown in the figure), the bus bar can be directly welded and electrically connected to the center of the first surface 121, which can reduce the interference of the welding sites 122 on the connection of the bus bar. Since the protective member 30 does not cover all the welding sites 122, the protective member 30 is also arranged away from the center of the first surface 121, which can reduce the interference of the protective member 30 on the connection of the bus bar.

[0058] In addition, referring further to FIG. 5, the first end portion 12 of the cylindrical battery 100 is usually provided with a chamfer 123, which is smoothly connected to the main body portion 11. The chamfer 123 can make the stress distribution of the cylindrical battery 100 more uniform, reduce the stress concentration at the chamfer 123 of the first end portion 12, and reduce the risk of damage of the cylindrical battery 100 due to excessive stress. When the cylindrical battery 100 is installed in an electronic device, the chamfer 123 can make the cylindrical battery 100 more easily inserted or clamped into the corresponding position, improving the convenience of installation. Moreover, the provision of the chamfer 123 can make the structure of the first end portion 12 of the cylindrical battery 100 more stable and reduce the structural deformation caused by shape mutation.

[0059] Usually, the width of the chamfer 123 is less than 0.05R to ensure the energy density of the cylindrical battery 100. In the embodiments of the present application, L≤0.95R is defined, which can reduce the influence of the chamfer 123 on welding, and reduce the problems of false welding and insufficient welding tension caused by the chamfer 123.

[0060] In the embodiments of the present application, at least part of the welding sites 122 are exposed to the protective member 30.

[0061] Please refer to FIG. 6, when the protective member 30 covers part of the welding site 122, the distance between the inner edge of the welding site 122 and the center of the first surface 121 is L1, the distance between the outer edge of the welding site 122 and the center of the first surface 121 is L2, the distance between the inner edge of the protective member 30 and the center of the first surface 121 is L3, and 0

[0062] In some embodiments, the welding site 122 is arc-shaped, which is more convenient for the protective member 30 to cover. For example, along the width direction of the welding site 122, the center of the welding site 122 divides the welding site 122 into two parts, one part is close to the center of the first surface 121, and the other part is far away from the center of the first surface 121. The protective member 30 encloses a circle on the first surface 121, which can facilitate covering the part of the welding site 122 far away from the center of the first surface 121. On the one hand, it can increase the coverage area of the protective member 30 on the welding site 122, reduce the corrosion of the welding site 122, and on the other hand, it can reduce the overlap between the protective member 30 and the highest part of the center of the welding site 122. Optionally, the distance between the center of the arc-shaped welding site 122 and the center of the first surface 121 is 0mm to 1mm, or the curvature of the welding site 122 is similar to the curvature of the protective member 30 on the first surface 121, which is more conducive to increasing the coverage area of the protective member 30 on the welding site 122 and reducing the overlap between the protective member 30 and the highest part of the center of the welding site 122.

[0063] Please refer to FIG. 7, when the protective member 30 does not cover the welding site 122, the distance between the inner edge of the protective member 30 and the outer edge of the welding site 122 is L4, which satisfies 0≤L4≤0.5R, so that the welding site 122 has enough distance from the center of the first surface 121 for welding connection with external circuits and convenient contact test by probes. Preferably, 0≤L4≤0.2R, which further improves the convenience of welding the first surface 121 with external circuits and the convenience of contact of the probes with the first surface 121.

[0064] In some embodiments, referring further to FIG. 8, the outer surface of the welding sites 122 is provided with a protective layer 50 (the part of the welding sites 122 covered by the protective layer 50 is shown by the dashed line in the figure). Since part of the welding sites 122 is exposed to the protective member 30, the protective member 30 cannot effectively protect this part of the welding sites 122, and rust may occur on the welding sites 122 after long-term use. By providing the protective layer 50, the erosion of the welding sites 122 by external water vapor, dust, etc. can be reduced, and rust on the welding sites 122 can be reduced. The protective layer 50 can be an oil-soluble rust inhibitor (such as petroleum barium sulfonate, lanolin and its derivatives, etc.), a water-soluble rust inhibitor (such as nitrite, phosphate, silicate, etc.), a hard film rust inhibitor (such as silicone resin, acrylic resin, etc.), and a wax film rust inhibitor (such as paraffin wax, microcrystalline wax, etc.), etc.

[0065] The dosage of the protective layer 50 can be confirmed by testing the fluorescence intensity Q of the protective layer 50 in the welding site 122 area in the RFU mode of the fluorescence detector, which is used to represent the dosage of the protective layer 50. If the dosage of the protective layer 50 is too small, it is easy to cause rust on the welding sites 122, and if the dosage of the protective layer 50 is too large, it will affect the welding connection between the first surface 121 and the external circuit. In some embodiments, the fluorescence intensity of the protective layer 50 at the welding sites 122 is Q, 5≤Q≤600, which can reduce rust on the welding sites 122 while facilitating the welding connection between the first surface 121 and the external circuit, and improving the connection strength.

[0066] The inventors of the present application have found that the area of the welding sites 122 affects the overcurrent temperature rise of the first end portion 12, and when the total area of the welding sites 122 is less than 0.2mm 2 , the overcurrent area is insufficient, local heating is serious, and the overall temperature rise of the cylindrical battery 100 is high. When the total area of the welding sites 122 is greater than 0.8mm 2 , it will affect the welding connection between the first end portion 12 and the external circuit, and will interfere with the probe.

[0067] In some embodiments, as observed along the axial direction X of the cylindrical battery 100, the sum of the projection areas of all the welding sites 122 on the first surface 121 is S, 0.2mm 2 ≤S≤0.8mm 2 , which not only meets the overcurrent temperature rise requirement of the cylindrical battery 100 (temperature rise <60℃), but also meets the welding strength requirement (welding tensile strength specification >10N), and also reduces the interference with the external circuit welding and the probe.

[0068] In some embodiments, at least two welding sites 122 are arranged around the center of the first surface 121, such that each welding site 122 is arranged around the first surface 121 at least once. By arranging the welding sites 122 around the first end 12, the contact area of the welding can be increased, and the strength and stability of the welding can be improved. The cylindrical battery 100 can better withstand vibrations and impacts during use, and the risk of cracks or looseness at the welding site can be reduced. Moreover, the arrangement of the welding sites 122 around the first end 12 can make the current more uniformly distributed, which can help reduce the concentration of current in a local area, reduce the resistance, and reduce heat generation.

[0069] In other embodiments, at least one welding site 122 can also be arranged around the center of the first surface 121 at least once. Please refer to FIG. 9 and FIG. 10, wherein FIG. 9 shows a structure in which one welding site 122 is arranged around once, and FIG. 10 shows a structure in which one welding site 122 is arranged around multiple times. Such structures can also improve the strength of the welding, and when one welding site 122 is used, the welding operation can be continuous and uninterrupted, and the welding efficiency can be improved.

[0070] In some embodiments, please refer to FIG. 11 and FIG. 12, the cylindrical battery 100 further includes a current collector 40, which is arranged in the housing 10 and is electrically connected between the electrode assembly 20 and the first end 12. The above-mentioned welding site 122 is configured to be welded to the current collector 40.

[0071] The above-mentioned negative tab is directly electrically connected to the current collector 40, or a plurality of negative tabs or an empty foil area without a material layer are flattened to form a negative flattened surface, and then the current collector 40 is electrically connected to the negative flattened surface. Then, the first end 12 and the current collector 40 are welded by laser penetration welding, so that the first end 12 leads out the negative electrode.

[0072] The collector plate 40 can effectively collect the current generated inside the cylindrical battery 100 and conduct the current to the external circuit uniformly and efficiently, ensuring that the current can be stably and smoothly output, and improving the performance and efficiency of the cylindrical battery 100. For example, in high discharge rate applications, the collector plate 40 can quickly collect and deliver a large amount of current, meeting the demand for large rate charging and discharging of the cylindrical battery 100. Moreover, the collector plate 40 can reduce the transmission resistance of the current inside the cylindrical battery 100, reducing energy loss. The collector plate 40 can be made of a highly conductive material, such as copper or aluminum, which can effectively reduce resistance and improve the output power of the cylindrical battery 100. Moreover, the collector plate 40 can provide mechanical support for the electrode assembly 20, increasing the overall structural strength and stability of the cylindrical battery 100. When the cylindrical battery 100 is subjected to external forces such as vibration and impact, the collector plate 40 can reduce the deformation and damage of the electrode assembly 20. At the same time, the collector plate 40 provides a more convenient connection point, making the connection of the electrode assembly 20 and the first end portion 12 simpler and more reliable.

[0073] In the present application, the welding site 122 can be extended from the first surface 121 to the collector plate 40 by laser penetration welding, wherein the welding site 122 includes a first portion 1221 located on the collector plate 40. In the direction from the first end portion 12 to the collector plate 40, the thickness of the first portion 1221 is T1, and the thickness of the collector plate 40 is T2, 2 μm ≤ T1 < T2, which improves the welding strength of the collector plate 40 and the first end portion 12. For example, by laser penetration welding, the laser melts the first end portion 12 and melts part of the collector plate 40, and the melting depth on the collector plate 40 is T1. After solidification, the first portion 1221 is formed, so that the first end portion 12 is connected to the collector plate 40.

[0074] In other embodiments, the collector plate 40 can also be provided between the electrode assembly 20 and the second end portion 13, for example, the positive tab of the electrode assembly 20 is welded to the collector plate 40, and then the collector plate 40 is welded to the second end portion 13, so that the second end portion 13 leads out the positive electrode. This can further improve the current carrying capacity of the cylindrical battery 100 and meet the large rate charging and discharging requirements of the cylindrical battery 100.

[0075] The second aspect of the present application also provides an electronic device comprising the cylindrical battery 100 according to any one of the embodiments of the first aspect described above, wherein the cylindrical battery 100 is used to power the electronic device. The electronic device according to the embodiments of the present application is not particularly limited and can be any electronic device known in the art. For example, the electronic device includes but is not limited to a Bluetooth headset, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric car, an electric vehicle, a ship, a spacecraft, an energy storage device, etc. Among them, the electric toy can include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, an electric plane toy, etc., and the spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0076] Experiment 1: Preparation of lithium ion cylindrical battery

[0077] Example 1

[0078] <Preparation of positive electrode sheet>:

[0079] The positive electrode active material lithium iron phosphate, the positive electrode conductive agent acetylene black, and the positive electrode binder polyvinylidene fluoride (PVDF, weight average molecular weight 5 x 10 5 ) in a mass ratio of 94:3:3 were mixed, N-methyl pyrrolidone (NMP) was added as a solvent, a positive electrode slurry with a solid content of 75wt% was prepared, and the positive electrode slurry was stirred uniformly in a vacuum stirrer. An aluminum foil with a thickness of 10μm was selected as the positive electrode current collector, the positive electrode slurry was uniformly coated on one surface of the positive electrode current collector aluminum foil, and a blank area of the aluminum foil where no positive electrode slurry was coated was reserved, and the aluminum foil was dried at 110°C to obtain a positive electrode sheet with a single-sided positive electrode active material layer. Then, the above steps were repeated on the other surface of the aluminum foil to obtain a positive electrode sheet with a double-sided positive electrode active material layer. The coating weight of the positive electrode sheet was 22.33mg / cm 2 .

[0080] <Preparation of negative electrode sheet>

[0081] The negative electrode active material graphite powder, the conductive agent conductive carbon black (Super P), and the binder styrene butadiene rubber (SBR) were mixed in a weight ratio of 97.5:1:1.5, deionized water was then added as a solvent, a negative electrode slurry with a solid content of 50wt% was prepared, and the negative electrode slurry was stirred uniformly. A copper foil with a thickness of 6μm was selected as the negative electrode current collector, the negative electrode slurry was uniformly coated on one surface of the negative electrode current collector copper foil, and a blank area of the copper foil where no negative electrode slurry was coated was reserved, and the copper foil was dried at 90°C to obtain a single-sided negative electrode sheet. After the above steps were completed, the single-sided coating of the negative electrode sheet was completed. Then, the above steps were repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet with a double-sided negative electrode active material layer. The coating weight of the negative electrode sheet was 6.64mg / cm 2.

[0082] <Preparation of the separator film>

[0083] A porous polyethylene (PE) film with a thickness of 8 μm was used as the separator film.

[0084] <Preparation of the electrolyte>

[0085] In a dry argon atmosphere, ethylene carbonate, methyl ethyl carbonate and diethyl carbonate were mixed in a mass ratio of 30:50:20 to obtain an organic solution, then lithium salt lithium hexafluorophosphate was added to the organic solvent to dissolve and mix uniformly, to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0086] <Preparation of the lithium ion battery>

[0087] The separator film, the positive electrode sheet, the separator film, and the negative electrode sheet prepared above were stacked in order and wound to obtain an electrode assembly. The electrode assembly was subjected to hot pressing (pressure 5 MPa, temperature 65°C, pressure maintaining time 10 s). The positive electrode empty foil area was rubbed flat to form a positive electrode rubbing plane, and the negative electrode empty foil area was rubbed flat to form a negative electrode rubbing plane. The electrode assembly was placed in a cylindrical steel shell, and the positive electrode rubbing plane and the negative electrode rubbing plane were respectively welded to the current collector plates in the shell. The first end portion was laser penetration welded to the current collector plate of the negative electrode, thereby leading out the negative electrode terminal. The distance between the center of the first end portion and the outer periphery of the first end portion was R = 10 mm, and the distance from the welding position to the center of the first end portion was L = 5 mm, L / R = 0.5. The second end portion was directly welded to the current collector plate of the positive electrode, thereby leading out the positive electrode terminal. After removing the water at 80°C, the electrolyte was injected and a protective member was provided, which was partially located at the first end portion and did not cover the welding position of the laser penetration welding. The total area of the welding position was 0.5 mm 2 A rust-proof oil was applied to the exposed welding position, and the dosage of the rust-proof oil was represented by a fluorescence value Q, Q = 162.

[0088] Probe test: the first end portion of the cylindrical battery prepared above was placed upward, one end of a probe was placed in contact with the first end portion, a force of 2 N was applied to the probe towards the cylindrical battery, and whether the electrical connection between the probe and the cylindrical battery was disconnected was observed. Disconnection was regarded as test failure.

[0089] Fluorescence test: the SITA instrument was adjusted to RUF mode, the welding position area was measured, and the average value was taken as the fluorescence value Q of the cylindrical battery in RUF mode.

[0090] Salt spray test: test chamber temperature: 35±1℃; salt water concentration: 5%±0.1%(m / m); salt solution pH: 7.0; after 24H, observe the corrosion(yellowing) degree of the welding position.

[0091] The relevant test data of Examples 1 to 2 and Comparative Example 1 are shown in Table 1 below.

[0092] Table 1

[0093] According to Table 1 above, in combination with Examples 1 to 9 and Comparative Example 1, when the protective piece covers the welding position, the probe can be effectively prevented from sliding off the first end portion, which may be because the protective piece itself is soft, and when the probe contacts the first end portion, slight extrusion of the probe on the edge of the protective piece can cause the edge of the protective piece to deform, and the probe is also prone to sliding off the first end portion to the outer surface of the protective piece. Furthermore, the protective piece itself is ultra-thin, and after covering the welding position entirely, it is difficult to effectively limit the probe by relying on the protective piece alone. Moreover, the protective piece is made of insulating material, and the probe is prone to sliding onto the protective piece, causing the electrical connection between the probe and the first end portion to fail, affecting the test efficiency. Compared with limiting the probe by the protective piece, in Examples 1 to 9, the probe is limited by the uncovered part of the welding position, and the welding position has higher strength and can conduct electricity, which can facilitate the smooth performance of the formation or voltage test. In addition, the influence of the welding position on the protective piece can also be reduced, the length of the cylindrical battery caused by the overlap of the welding position and the protective piece can be reduced, and the energy density of the cylindrical battery can be improved.

[0094] The probe failure rate of Examples 3 to 9 is lower than that of Example 2. In Example 2, L / R is small, which can make the welding position closer to the center of the first end portion, and can make the test area defined by the first end portion smaller, so that the welding position is prone to interfere with the probe. Moreover, during the probe test, the probe can directly pierce the rust-proof oil, causing the welding position to be exposed, and during the salt spray test, the welding mark can appear yellow. In Example 9, the welding position is close to the edge of the first end portion, and due to the influence of the chamfer, not only is the welding inconvenient, but also the welding is prone to be not firm. Moreover, due to the proximity to the edge, the probe can directly slide off the first end portion. Therefore, in the present application, 0.5≤L / R≤0.95 is preferred.

[0095] It should be noted that due to errors in the test process, the Q values of the above Examples 1 to 9 and Comparative Example 1 can not be consistent, and within the allowable error range(10 or less) can be acceptable.

[0096] Unlike Example 3, the relevant test data of Examples 10 to 15 are shown in Table 2 below.

[0097] Table 2

[0098] According to the above Table 2, the yellowing degree of Examples 11 to 22 is less than that of Example 3, which can be due to the insufficient coating amount of the rust inhibitor in Example 3, which is prone to rust corrosion of the welding site. The present application can select the cleanliness fluorescence value as 5≤Q≤600, which can reduce the rust corrosion of the welding site. In Examples 11 to 13, there is still slight yellowing, and in Examples 20 to 22, the excessive amount of rust inhibitor can cause the cylindrical battery to be difficult to weld with the busbar, and cause waste of the rust inhibitor. In the present application, in combination with Examples 14 to 19, 102≤Q≤367 is preferred, which can further reduce the rust corrosion of the welding site, and can reduce the amount of rust inhibitor, facilitating the welding of the cylindrical battery with the busbar.

[0099] The total area of the welding site is calculated as follows: according to the different appearances of the welding site, such as the same multiple straight line welding sites, i.e. total area = nMK, where n is the number of welding sites, M is the length of a single welding site, and K is the width of a single welding site; if it is the same multiple arc welding sites, i.e. total area = nθπ(R 2 -r 2 ) / 360, where θ is the angle corresponding to the arc welding site, R is the outer arc radius of the arc welding site, and r is the inner arc radius of the arc welding site, and if it is the remaining non-circular arc line segment, the actual length * actual width of the welding site is measured by the point drawing function of the CAD software, and the sum of the areas of all non-circular arc line segments is added to obtain the total area.

[0100] Welding tensile test: the bottom of the welded steel shell and the current collector plate are cut off as a sample, a multifunctional tensile testing machine is used, one end clamps the steel shell and the other end clamps the current collector plate (a special clamp is needed), the stretching speed is 50 mm / min, and the test is carried out, when the sample is broken, the breaking tensile value F is obtained, i.e. the welding strength.

[0101] Temperature rise test: the cylindrical battery is placed in a constant temperature furnace at 25℃, and a temperature sensing line is attached to the center position of the surface of the cylindrical battery (i.e. along the axial X, the center position of the side wall of the shell), and the temperature data is tested under 2C discharge, and the obtained temperature data is subtracted by 25℃, i.e. the corresponding temperature rise data is obtained.

[0102] The relevant test data of Examples 23 to 29 are shown in Table 3 below.

[0103] Table 3

[0104] According to Table 3 above, in combination with Examples 23-29, the welding strength in Examples 24-29 is higher than that in Example 23, because the larger the welding area, the higher the connection strength, and the more stable the connection of the current collecting plate and the shell. Moreover, in Examples 24-29, the temperature rise is smaller than that in Example 23, because the larger the welding area, the larger the excess area, and the stronger the current carrying capacity, which can alleviate the temperature rise. In Example 29, the total welding area is too large, which affects the energy density, and the welding mark may also interfere with the installation of the cylindrical battery when the cylindrical battery is installed in an electronic device. Therefore, in the present application, 0.2mm 2 ≤ S ≤ 0.8mm 2 .

[0105] The above description is only an example of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A cylindrical battery comprising a housing and an electrode assembly, the housing having a first end portion with a first surface facing away from the electrode assembly along an axial direction of the electrode assembly, the electrode assembly being disposed in the housing, the first end portion having at least one welding site provided on the first surface, characterized in that, the cylindrical battery further comprises a protective member disposed on the housing and covering part of the first surface, and at least part of the welding site is exposed to the protective member.

2. The cylindrical battery according to claim 1, characterized by A minimum distance between a center of the first surface and an outer periphery of the first end portion is R, a distance between a center of the welding site and the center of the first surface is L, and 0.5R≤L≤0.95R.

3. The cylindrical battery according to claim 1, wherein The protective member covers part of the welding site, a distance between an inner edge of the welding site and the center of the first surface is L1, a distance between an outer edge of the welding site and the center of the first surface is L2, a distance between an inner edge of the protective member and the center of the first surface is L3, and 0 4. The cylindrical battery according to claim 3, characterized by The welding site is in an arc shape.

5. The cylindrical battery of claim 2, wherein, The protective member does not cover the welding site, a distance between an inner edge of the protective member and an outer edge of the welding site is L4, and 0≤L4≤0.5R is satisfied.

6. The cylindrical battery of claim 5, wherein, 0≤L4≤0.2R.

7. The cylindrical battery of claim 1, wherein, An outer surface of the welding site is further provided with a protective layer.

8. The cylindrical battery of claim 7, wherein, In an RFU mode of a fluorescence detector, a fluorescence intensity of the protective layer at the welding site is Q, and 5≤Q≤600.

9. The cylindrical battery of claim 1, wherein, The sum of the projected areas of all the weld sites on the first surface, as viewed along the axial direction, is S, 0.2mm 2 ≤ S ≤ 0.8mm 2 .

10. The cylindrical battery of claim 1, wherein, The at least one welding site surrounds the center of the first surface by at least one turn.

11. The cylindrical battery of claim 1, wherein, At least two welding sites are arranged around the center of the first surface.

12. The cylindrical battery according to any one of claims 1 to 11, characterized by, Further comprising a current collector plate disposed in the housing and electrically connected between the electrode assembly and the first end portion, the welding site is configured to be welded to the current collector plate; The welding site extends from the first surface to the current collector plate, and the welding site includes a first portion located on the current collector plate; In a direction from the first end portion to the current collector plate, a thickness of the first portion is T1, and a thickness of the current collector plate is T2, and 2μm≤T1 13. An electronic device, comprising: The cylindrical battery as claimed in any one of claims 1 to 12 is used to power the electronic device.

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