Battery and preparation method thereof and electronic product

Abstract

This invention provides a battery, its manufacturing method, and an electronic product. The battery includes a casing and a cell housed within the casing. The cell includes electrodes and tabs. The electrodes include a current collector and an active material layer. The current collector includes a coated area coated with the active material layer and an uncoated foil area. One end of the tab overlaps the uncoated foil area, and the tab and the uncoated foil area are fixedly connected by laser welding. The side of the uncoated foil area opposite to the tab has multiple spaced dot-shaped solder marks, each including a recess and an annular protrusion surrounding the recess. The side of the tab opposite to the uncoated foil area has no solder marks. The annular protrusion of this invention has a relatively large contact area with the separator between the positive and negative electrodes, making it less likely to puncture the separator and thus preventing short circuits, which is beneficial for improving the quality and safety performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and more particularly to a battery, its preparation method, and electronic products. Background Technology

[0002] With the development of science and technology, electronic products are increasingly entering all aspects of people's lives. The normal use of electronic products is inseparable from batteries. Among them, lithium-ion batteries have been widely used in electronic products in various fields due to their advantages such as high energy density and environmental friendliness. Furthermore, with the development of electric vehicle technology, the application of lithium-ion batteries in the field of electric vehicles has also attracted much attention.

[0003] With the increasingly widespread application of lithium-ion batteries, their quality and safety performance have received increasing attention. In existing lithium-ion batteries, the electrode and tab are connected together by ultrasonic welding. Specifically, the welding head contacts the tab side and applies pressure and vibration to weld the tab to the electrode.

[0004] However, after ultrasonic welding is completed, a structure like this will form on the electrode side. Figure 1 The needle-like welding protrusion shown can easily pierce the diaphragm between the positive and negative electrodes, causing a short circuit between the positive and negative electrodes, which may lead to serious safety problems. Summary of the Invention

[0005] This invention provides a battery, a method for manufacturing the same, and an electronic product thereof. The protrusions formed after welding the electrodes and tabs of the battery are less likely to puncture the separator between the positive and negative electrodes, thereby preventing short circuits and improving the quality and safety performance of the battery.

[0006] In a first aspect, the present invention provides a battery comprising a casing and a battery cell housed within the casing. The battery cell includes an electrode and a tab. The electrode includes a current collector and an active material layer. The current collector includes a coated area coated with the active material layer and an empty foil area uncoated with the active material layer. One end of the tab overlaps the empty foil area, and the tab and the empty foil area are fixedly connected by laser welding. The side of the empty foil area opposite to the tab has a plurality of spaced dot-shaped solder marks, each dot-shaped solder mark including a recess and an annular protrusion surrounding the recess. The side of the tab opposite to the empty foil area has no solder marks.

[0007] The battery of the present invention includes a casing and a cell housed within the casing. The cell includes electrodes and tabs. The electrodes include a current collector and an active material layer. The current collector includes a coated area coated with the active material layer and an empty foil area uncoated with the active material layer. By overlapping one end of the tab with the empty foil area and fixing the tab and the empty foil area together by laser welding, the battery performance can be avoided due to wear of the welding head causing poor or over-welded connections, and the work of replacing the welding head is eliminated. After laser welding, multiple spaced dot-shaped weld marks are formed on the side of the empty foil area away from the tab. The dot-shaped weld marks include recesses and annular protrusions surrounding the recesses. Since the contact area between the annular protrusions and the separator is larger than that of the needle-shaped welding protrusions in the prior art, the pressure between the annular protrusions and the separator is smaller. Therefore, the annular protrusions are less likely to puncture the separator between the positive and negative electrodes, thereby preventing short circuits and improving the quality and safety performance of the battery. Furthermore, there is no solder mark on the side of the tab away from the empty foil area. This means that the side of the tab away from the empty foil area can maintain the original flatness of the tab during the welding process, thereby avoiding the formation of a structure that is detrimental to the separator during the welding process, which in turn helps to improve the quality and reliability of the battery.

[0008] In the battery described above, optionally, the height of the annular protrusion is less than 30 micrometers; the depth of the recess is less than the sum of the thickness of the empty foil area and the tab.

[0009] In the battery described above, optionally, the depth of the recess is between 20 micrometers and 70 micrometers.

[0010] As described above, the sidewalls of the recessed portion may optionally have at least a partially cylindrical or frustum-shaped wall surface.

[0011] In the battery described above, optionally, the diameter of the dotted solder marks is between 50 micrometers and 300 micrometers; and / or, the spacing between two adjacent dotted solder marks is not less than 100 micrometers.

[0012] As described above, the battery may optionally have multiple dot-matrix arrays arranged; and / or the number of dot-matrix arrays may be between 150 and 800.

[0013] In the battery described above, optionally, the minimum distance between the dotted solder mark and the coating area is greater than 1 mm; and / or, the empty foil area is located in the middle of the electrode sheet.

[0014] Optionally, in the battery described above, the bottom surface of the recess has a central protrusion, the height of which is less than the depth of the recess.

[0015] Secondly, the present invention provides a method for manufacturing a battery, comprising: providing an electrode sheet, a tab, and a separator, wherein the electrode sheet has a coated area and a blank foil area; attaching the blank foil area to the tab; performing pulse spot welding from the side surface of the blank foil area away from the tab using a laser welding device to form a plurality of spaced dot-shaped weld marks; the dot-shaped weld marks include a recessed portion and an annular protrusion surrounding the recessed portion; the side surface of the tab away from the blank foil area has no weld marks; processing the electrode sheet with the tab welded thereto and the separator together to form a battery cell; and assembling the battery cell into a casing to form a battery.

[0016] The battery preparation method of the present invention involves attaching the empty foil area of ​​the electrode sheet to the tab, and then using a laser welding device to perform pulse spot welding from the surface of the empty foil area away from the tab to form multiple spaced dot-shaped weld marks. Using laser welding avoids the impact on battery performance caused by weld head wear leading to incomplete or over-welded connections, and also eliminates the need to replace the weld head. Furthermore, the dot-shaped weld marks formed by laser welding include recesses and annular protrusions surrounding the recesses. Since the contact area between the annular protrusions and the separator is larger than that of the needle-shaped welding protrusions in existing technologies, the pressure between the annular protrusions and the separator is lower. This makes it less likely for the annular protrusions to puncture the separator between the positive and negative electrode sheets, thereby preventing short circuits and improving battery quality and safety performance. Furthermore, there is no solder mark on the side of the tab away from the empty foil area. This means that the side of the tab away from the empty foil area can maintain the original flatness of the tab during the welding process, thereby avoiding the formation of a structure that is detrimental to the separator during the welding process, which in turn helps to improve the quality and reliability of the battery.

[0017] Thirdly, the present invention provides an electronic product including the battery described above.

[0018] The electronic product of this invention includes a battery, which includes a casing and a cell housed within the casing. The cell includes electrodes and tabs. The electrodes include a current collector and an active material layer. The current collector includes a coated area coated with the active material layer and an empty foil area uncoated with the active material layer. By overlapping one end of the tab with the empty foil area and fixing the tab and the empty foil area together by laser welding, it is possible to avoid the battery performance being affected by poor or excessive soldering due to wear of the welding head, and to eliminate the need to replace the welding head. After laser welding, multiple spaced dot-shaped solder marks are formed on the side of the empty foil area away from the tab. The dot-shaped solder marks include recesses and annular protrusions surrounding the recesses. Since the contact area between the annular protrusions and the separator is larger than that of the needle-shaped welding protrusions in the prior art, the pressure between the annular protrusions and the separator is smaller. This makes it less likely for the annular protrusions to puncture the separator between the positive and negative electrodes, thereby preventing short circuits and improving the quality and safety performance of the battery. Furthermore, there is no solder mark on the side of the tab away from the empty foil area. This means that the side of the tab away from the empty foil area can maintain the original flatness of the tab during the welding process, thereby avoiding the formation of a structure that is detrimental to the separator during the welding process, which in turn helps to improve the quality and reliability of the battery. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a microscope image of the needle-like welding protrusions formed on the electrode side after ultrasonic welding in the prior art.

[0021] Figure 2 This is a cross-sectional view of the dotted solder marks formed after the electrode and tab of the battery cell are welded together, according to Embodiment 1 of the present invention.

[0022] Figure 3 This is a schematic diagram of the structure of the electrode side of the battery cell after the electrode and the tab are welded together, according to Embodiment 1 of the present invention.

[0023] Figure 4 This is a schematic diagram of the electrode side of the battery cell after the electrode sheet and electrode tab are welded together, according to Embodiment 1 of the present invention.

[0024] Figure 5 This is a microscope image of the dotted solder marks formed after the electrode and tab of the battery cell are welded together, as provided in Embodiment 1 of the present invention.

[0025] Explanation of reference numerals in the attached figures:

[0026] 20-electrode film;

[0027] 21- Dotted solder marks;

[0028] 211 - Depression;

[0029] 212 - Annular protrusion;

[0030] 213 - Central protrusion;

[0031] 30-Ear. Detailed Implementation

[0032] In existing technologies, the tabs and electrodes of a battery cell are usually connected by ultrasonic welding. Ultrasonic welding requires the welding head to contact the tab side and apply pressure and vibration to weld the tab and electrode together. During this process, the welding head will wear out. On the one hand, this can easily lead to problems such as poor welding or over-welding between the tab and electrode, which will affect the performance of the battery. On the other hand, the welding head needs to be replaced regularly, which increases the workload.

[0033] At the same time, ultrasonic welding will form a shape on the electrode side such as Figure 1 The needle-shaped welding protrusion shown has a contact area with the separator between the positive and negative electrode plates that is only the size of the area at the tip of the needle-shaped welding protrusion. This results in a relatively high pressure between the needle-shaped welding protrusion and the separator, making it easier for the needle-shaped welding protrusion to pierce the separator, causing a short circuit between the positive and negative electrode plates, which may lead to serious safety problems.

[0034] To address the aforementioned technical problems, this invention provides a battery in which the electrode and tab are fixedly connected by laser welding. Laser welding utilizes a high-energy-density laser beam as a heat source to weld the electrode and tab from the electrode side. Laser welding eliminates the problem of welding head wear, thus avoiding issues like incomplete or over-welded connections caused by welding head wear, and also eliminating the need to replace welding heads, which increases workload. Furthermore, the contact area between the annular protrusion formed after laser welding and the separator is the entire apex of the annular protrusion, significantly larger than the contact area between the needle-shaped welding protrusion and the separator in existing technologies. Therefore, the pressure between the annular protrusion and the separator is relatively low, making it less likely for the annular protrusion to puncture the separator between the positive and negative electrodes, leading to a short circuit. This, in turn, improves the battery's quality and safety performance.

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] Figure 2 This is a cross-sectional view of the dotted solder marks formed after the electrode and tab of the battery cell are welded together, according to Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of the structure of the electrode side of the battery cell after the electrode and the tab are welded together, according to Embodiment 1 of the present invention. Figure 4 This is a schematic diagram of the electrode side of the battery cell after the electrode sheet and electrode tab are welded together, according to Embodiment 1 of the present invention. Figure 5 This is a microscope image of the dotted solder marks formed after the electrode and tab of the battery cell are welded together, as provided in Embodiment 1 of the present invention.

[0038] Reference Figures 2 to 5 As shown, this embodiment provides a battery, which includes a casing and a battery cell housed within the casing. The battery cell includes an electrode 20 and a tab 30. The electrode 20 includes a current collector and an active material layer. The current collector includes a coated area coated with the active material layer and an empty foil area uncoated with the active material layer. One end of the tab 30 overlaps with the empty foil area, and the tab 30 and the empty foil area are fixedly connected by laser welding.

[0039] The battery cell can be either a wound cell or a laminated cell; the electrode can be either a positive electrode or a negative electrode. The electrode includes a current collector and an active material layer coated on the surface of the current collector. To weld the tab to the current collector of the electrode, an uncoated foil area needs to be left on the surface of the current collector, or the active material layer in a portion of the current collector surface needs to be removed to expose the current collector. The exposed current collector surface is the uncoated foil area, and the area covered by the active material layer is the coated area. Typically, the current collector for the positive electrode is aluminum foil, and the current collector for the negative electrode is copper foil.

[0040] Specifically, a wound cell includes a positive electrode, a negative electrode, and a separator that separates the positive and negative electrodes; a positive tab is welded onto the positive electrode, and a negative tab is welded onto the negative electrode; during the winding process, the positive electrode, the separator, and the negative electrode are wound in the same direction from the beginning of the winding and finally form a wound cell.

[0041] A laminated battery cell includes a positive electrode, a negative electrode, and a separator that separates the positive and negative electrodes. A positive electrode tab is welded onto the positive electrode, and a negative electrode tab is welded onto the negative electrode. During the manufacturing process, the positive and negative electrodes are alternately stacked, and a separator is stacked between two adjacent positive and negative electrodes to finally form a laminated battery cell.

[0042] Normally, laser welding is performed on the tab 30 and the tab 20 from the side of the electrode 20. After laser welding is completed, multiple spaced dot-shaped weld marks 21, such as round dot-shaped weld marks, will be formed on the surface of the empty foil area away from the tab. Specifically, the dot-shaped weld marks 21 include a recess 211 and an annular protrusion 212 surrounding the recess 211.

[0043] In this embodiment, there are no solder marks on the side of the tab 30 facing away from the empty foil area. Since laser welding is performed on the side of the empty foil area facing away from the tab 30, the dotted solder marks 21 are only formed on the side of the empty foil area facing away from the tab 30. The side of the tab 30 facing away from the empty foil area retains its original surface. In other words, the original flatness of the side of the tab 30 facing away from the empty foil area will not be affected by welding, thereby avoiding the formation of a structure that is detrimental to the diaphragm on the surface of the tab 30 during the welding process.

[0044] In practice, firstly, one end of the tab 30 is overlapped and bonded to the empty foil area of ​​the electrode 20. For example, a pressure clamp or an adsorption clamp can be used to ensure a tight bond between the empty foil area of ​​the electrode 20 and the tab 30, preventing the electrode 20 from being welded through due to insufficient bonding. Then, after setting the process parameters of the laser welding equipment, the laser welding equipment performs pulse spot welding on the tab 30 and the electrode 20 from the side of the empty foil area away from the tab 30, forming a dot-shaped weld mark 21 on the side of the empty foil area away from the tab 30, while there is no weld mark on the side of the tab 30 away from the empty foil area. The dot-shaped weld mark 21 includes a recessed portion 211 and an annular protrusion 212 surrounding the recessed portion 211. The recessed portion 211 can be, for example, a circular pit, and the annular protrusion 212 is the annular protrusion surrounding the circular pit.

[0045] The battery in this embodiment includes a casing and a cell housed within the casing. The cell includes an electrode 20 and a tab 30. The electrode 20 includes a current collector and an active material layer. The current collector includes a coated area with the active material layer and an empty foil area without the active material layer. By overlapping one end of the tab 30 with the empty foil area and fixing the tab 30 to the empty foil area of ​​the electrode 20 by laser welding, it is possible to avoid the battery performance being affected by poor welding or over-welding due to wear of the welding head, and to eliminate the need to replace the welding head. After laser welding is completed, multiple spaced dot-shaped weld marks 21 will be formed on the surface of the empty foil area of ​​the electrode 20 away from the tab. The dot-shaped weld marks 21 include a recessed portion 211 and an annular protrusion 212 surrounding the recessed portion 211. Because the contact area between the annular protrusion 212 and the separator is larger than that of the needle-shaped welding protrusion in the prior art, the pressure between the annular protrusion 212 and the separator is relatively small. This makes it less likely for the annular protrusion 212 to puncture the separator between the positive and negative electrodes, thus preventing short circuits and improving battery quality and safety. Furthermore, the side of the tab 30 facing away from the empty foil area has no solder marks. This means that the side of the tab 30 facing away from the empty foil area can maintain its original flatness during welding, preventing the formation of structures detrimental to the separator and further improving battery quality and reliability.

[0046] Specifically, in this embodiment, after laser welding, the height of the annular protrusion 212 of the dotted weld mark 21 formed on the electrode 20 side is less than 30 micrometers; while in the prior art, the height of the needle-shaped weld protrusion formed on the electrode side after ultrasonic welding reaches more than 80 micrometers. It can be seen that the height of the annular protrusion 212 in this embodiment is relatively low, which makes it less likely to puncture the separator between the positive and negative electrode sheets, thereby preventing short circuits and improving the quality and safety performance of the battery.

[0047] Normally, the separator located on the tab 30 side is relatively close to the tab 30, so it is easier to puncture the separator if a protrusion is formed on the tab 30 side. However, the depth of the recess 211 in this embodiment is less than the sum of the thickness of the empty foil area of ​​the electrode 20 and the thickness of the tab 30. In other words, the recess 211 of the dot-shaped solder mark 21 will not form a protrusion on the tab 30 side, thereby avoiding puncturing the separator on the tab 30 side and causing a short circuit, which is beneficial to improving the quality and safety performance of the battery.

[0048] Furthermore, the depth of the recess 211 is between 20 micrometers and 70 micrometers. Typically, the thickness of the current collector of the electrode is between 5 micrometers and 15 micrometers, and the thickness of the tab is between 30 micrometers and 100 micrometers. In practice, the laser energy can be adjusted according to actual needs to make the depth of the recess 211 between 20 micrometers and 70 micrometers, as long as it can be ensured that the recess 211 does not form a protrusion on the side of the tab 30, or that the electrode 20 and the tab 30 are not soldered through.

[0049] Reference Figure 2 As shown, the sidewall of the recess 211 in this embodiment has at least a partially cylindrical or frustum-shaped wall surface. In other implementations, the sidewall of the recess 211 may also be formed as a frustum-shaped wall surface, and the end of the frustum-shaped wall surface near the bottom surface of the recess 211 is smaller than the end of the frustum-shaped wall surface away from the bottom surface of the recess 211.

[0050] In this embodiment, the diameter of the dot-shaped solder mark 21 is between 50 micrometers and 300 micrometers. In practice, when the diameter of the dot-shaped solder mark 21 is too small, it is easy to cause poor welding effect between the electrode 20 and the tab 30; when the diameter of the dot-shaped solder mark 21 is too large, it is not conducive to the arrangement of the dot-shaped solder mark 21 on the electrode 20.

[0051] In this embodiment, the spacing between two adjacent dot-shaped solder marks 21 is not less than 100 micrometers. When the spacing between two adjacent dot-shaped solder marks 21 is too small, the heat dissipation during the welding process will be poor, which will lead to heat accumulation and further cause the electrode 20 to oxidize and turn black or even perforate. This will affect the welding effect between the electrode 20 and the tab 30, and will also be detrimental to the quality and safety performance of the battery.

[0052] In one implementation, refer to Figure 3 As shown, multiple dot-shaped solder marks 21 are arranged in an array on the side of the electrode 20. In specific implementation, the number of rows and columns of the dot-shaped solder marks 21 can be set according to actual needs, as long as the electrode 20 and the tab 30 can be firmly welded together and the power transfer effect between the electrode 20 and the tab 30 is good. No specific restrictions are imposed here.

[0053] In other implementations, the arrangement of multiple dot-shaped solder marks 21 on the electrode 20 side can also be adjusted according to actual needs, as long as it meets the requirements of this embodiment, which will not be elaborated here.

[0054] Furthermore, in this embodiment, the number of dot-shaped weld marks 21 is between 150 and 800, which on the one hand ensures that the welding pull between the electrode 20 and the tab 30 meets the requirements, and on the other hand ensures the efficiency of laser welding.

[0055] To prevent the laser used for welding from impacting the coating area of ​​the electrode 20 and affecting the active material layer of the electrode 20 during the laser welding process, this embodiment sets the minimum distance between the dotted weld mark 21 and the coating area of ​​the electrode 20 to be greater than 1 mm. This can prevent accidental damage to the active material layer of the electrode during the welding process, thereby helping to ensure that the quality of the battery is not affected.

[0056] Normally, the empty foil area is located at the head or tail of the current collector in the electrode sheet. When the tab 30 is welded to the empty foil area of ​​the electrode sheet 20, the tab 30 is located at the head or tail of the electrode sheet 20. To ensure the efficiency of power transfer between the electrode sheet 20 and the tab 30, the empty foil area of ​​the electrode sheet 20 can also be set in the middle of the electrode sheet 20. This can be achieved by removing part of the active material layer in the middle of the electrode sheet 20. For example, in a wound cell, the empty foil area can be set in the middle of the electrode sheet along its length; or in a laminated cell, the empty foil area can extend outward from the middle of the electrode sheet. In this case, when the tab 30 is welded to the empty foil area of ​​the electrode sheet 20, the tab 30 is located in the middle of the electrode sheet 20, which helps to improve the efficiency of power transfer between the tab 30 and the electrode sheet 20.

[0057] Reference Figure 2 As shown, the bottom surface of the recessed portion 211 in this embodiment has a central protrusion 213, and the height of the central protrusion 213 is less than the depth of the recessed portion 211. In specific implementation, since the height of the central protrusion 213 is less than the depth of the recessed portion 211, the central protrusion 213 does not contact the separator between the positive and negative electrode plates. In other words, the central protrusion 213 will not affect the separator between the positive and negative electrode plates.

[0058] This embodiment also provides a method for preparing a battery, including:

[0059] The system provides electrodes, tabs, and a separator. The electrodes have a coated area and a blank foil area. The blank foil area is bonded to the tab. A laser welding device performs pulsed spot welding on the surface of the blank foil area away from the tab to form multiple spaced dot-shaped weld marks. Each dot-shaped weld mark includes a recess and annular protrusions surrounding the recess. The surface of the tab away from the blank foil area has no weld marks. The electrodes with welded tabs and the separator are processed together to form a battery cell. The battery cell is then assembled into a casing to form a battery.

[0060] In practice, the electrode includes a positive electrode and a negative electrode, and the tab includes a positive tab and a negative tab. First, the empty foil area of ​​the positive electrode can be attached to the positive tab. For example, a pressure clamp or an adsorption clamp can be used to make the empty foil area of ​​the positive electrode tightly attached to the positive tab. Then, the parameters of the laser welding equipment are set. For example, the pulse frequency can be set to be greater than 500Hz and the pulse width to be less than 5ms. The laser welding equipment performs pulse spot welding on the positive tab and the positive electrode from one side of the positive electrode. The total welding time does not exceed 1 second, which will form multiple spaced dot-shaped weld marks on the surface of the positive electrode. Among them, the dot-shaped weld marks include a recessed part and an annular protrusion surrounding the recessed part. At the same time, there is no weld mark on the side of the tab away from the empty foil area.

[0061] Similarly, the empty foil area of ​​the negative electrode sheet can be attached to the negative electrode tab, and then the laser welding equipment can perform pulse spot welding on the negative electrode tab and the negative electrode sheet from one side of the negative electrode sheet. The total welding time does not exceed 1 second, which will form multiple spaced dot-shaped weld marks on the surface of the negative electrode sheet. Among them, the dot-shaped weld marks include the recessed part and the annular protrusion surrounding the recessed part. At the same time, there is no weld mark on the side of the electrode tab away from the empty foil area.

[0062] Finally, the positive electrode sheet with the positive tab welded on, the negative electrode sheet with the negative tab welded on, and the separator are processed together to form a battery cell. For example, it can be wound to form a wound battery cell or stacked to form a stacked battery cell.

[0063] In this embodiment, after the electrode sheet and the tab are welded together by laser welding, the welding pull force between the positive electrode sheet and the positive tab is measured to be greater than 25N, and the welding pull force between the negative electrode sheet and the negative tab is greater than 8N. Furthermore, after the pull force is applied to break the tab and the electrode sheet, the area of ​​the electrode sheet current collector remaining on the tab accounts for more than 50% of the entire welding area.

[0064] The procedure for measuring the welding pull force between the tab and the electrode using a tensile tester is as follows: First, use tape to stick the welding area to the side of the electrode; then, clamp the top of the tab with the upper part of the tensile tester and the bottom of the aluminum foil with the lower part of the tensile tester. At the same time, adjust the tensile force display mode to the peak display mode and set the tensile tester to zero to start the measurement: Press the "Up" button to pull 180° until the tab and the electrode separate; finally, read and record the value displayed on the tensile tester. Meanwhile, remove the tab and measure the ratio of the area of ​​the current collector remaining on the tab to the total area of ​​the welding area.

[0065] Example 2

[0066] This embodiment provides an electronic product, which includes a battery.

[0067] The battery in this embodiment has the same structure as the battery provided in Embodiment 1 and can bring the same or similar technical effects. It will not be described in detail here. For details, please refer to the description of the above embodiments.

[0068] In the description of this invention, it should be understood that the terms "top", "bottom", "upper", "lower" (if present) indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0069] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0070] The terms "first" and "second" in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery, characterized by, Includes a housing and a battery cell housed within the housing; The battery cell includes an electrode sheet and a tab. The electrode sheet includes a current collector and an active material layer. The current collector includes a coated area coated with the active material layer and an empty foil area uncoated with the active material layer. One end of the tab overlaps the empty foil area, and the tab is fixedly connected to the empty foil area. The side of the empty foil area facing away from the tab has a plurality of spaced dot-shaped solder marks, the dot-shaped solder marks including a recessed portion and an annular protrusion surrounding the periphery of the recessed portion. The side of the electrode tab opposite to the empty foil area has no solder marks; The spacing between two adjacent dot-shaped solder marks shall not be less than 100 micrometers; The tab is located in the middle of the electrode plate.

2. The battery of claim 1, wherein, The height of the annular protrusion is less than 30 micrometers; The depth of the recess is less than the sum of the thickness of the empty foil area and the tab.

3. The battery of claim 2, wherein, The depth of the recess is between 20 micrometers and 70 micrometers.

4. The battery according to any one of claims 1 to 3, characterized in that, The sidewall of the recess has at least a partially cylindrical or frustum-shaped wall surface.

5. The battery according to any one of claims 1 to 3, wherein The diameter of the dotted solder marks is between 50 micrometers and 300 micrometers.

6. The battery according to any one of claims 1 to 3, wherein Multiple dotted solder pad arrays are arranged in a single configuration; and / or, The number of the dotted solder marks is between 150 and 800.

7. The battery of any one of claims 1-3, wherein, The minimum distance between the dotted solder mark and the coated area is greater than 1 mm; and / or, The empty foil area is located in the middle of the electrode sheet.

8. The battery according to any one of claims 1-3, characterized in that, The bottom surface of the recess has a central protrusion, the height of which is less than the depth of the recess.

9. A method of producing a battery, characterized by, include: The system provides an electrode sheet, electrode tabs, and a diaphragm, wherein the electrode sheet has a coated area and an empty foil area; The empty foil area is attached to the electrode tab; The laser welding equipment performs pulse spot welding on the side surface of the empty foil area away from the electrode tab to form multiple spaced spot weld marks; the spot weld marks include a recessed portion and an annular protrusion surrounding the recessed portion; the side surface of the electrode tab away from the empty foil area has no weld marks. The spacing between two adjacent dot-shaped solder marks is not less than 100 micrometers; the tab is located in the middle of the electrode sheet; The electrode sheet with the above-mentioned welded tabs is processed together with the diaphragm to form a battery cell; The battery cells are assembled into the casing to form a battery.

10. An electronic product, characterized by comprising: Includes the battery as described in any one of claims 1-8.

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