Core pack, battery and battery pack

Abstract

The invention provides a core pack, a battery and a battery pack, the core pack comprises a pole piece assembly, the pole piece assembly comprises a plurality of pole pieces, and each pole piece comprises a tab; wherein the plurality of tabs are welded to form a welding printing area, the height of the folded tabs is H1, and the height of the welding printing area is H2; the core package is further provided with two opposite side faces in the thickness direction, the distance between the welding printing area and the side faces is D, the thickness of the core package is d, and 0.42 < = arctan ((H1-H2) / (d-D)) / arctan ((H1-H2) / D) < = 1.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a core pack, a battery and a battery pack. Background Art

[0002] The battery includes a core pack, the core pack includes a pole piece assembly, the pole piece assembly includes multiple pole pieces, each pole piece is provided with a pole ear, and multiple pole pieces correspond to multiple pole ears. The multiple pole ears are connected together by ultrasonic welding. In the process of ultrasonic welding of multiple pole ears, defects such as cold welding and leaking welding may occur, thereby affecting the welding effect and welding tension, and further causing the pole ear to break and reducing the safety performance of the battery cell. Summary of the invention

[0003] The embodiments of the present invention provide a battery core pack, a battery and a battery pack, which can improve the technical problem of insufficient tension in the welding of the tabs.

[0004] In a first aspect, an embodiment of the present invention provides a core pack for a battery, the core pack comprising: a pole piece assembly, the pole piece assembly comprising a plurality of pole pieces, each of the pole pieces comprising a pole ear; wherein a plurality of the pole ears are welded to form a weld print area, the height of the pole ear after folding is H1, and the height of the weld print area is H2; the core pack further comprises two side surfaces opposite to each other in a thickness direction, the distance between the weld print area and the side surfaces is D, and the thickness of the core pack is d, wherein 0.42≤arctan((H1-H2) / (dD)) / arctan((H1-H2) / D)≤1

[0005] In one embodiment, H1-H2≤d / 2.

[0006] In one embodiment, the height of the pole piece assembly is H, and the ratio of H1 to H is 0.08-0.28; and / or H1 satisfies: 14 mm ≤ H1 ≤ 22 mm.

[0007] In one embodiment, the height of the pole piece assembly is H, and the ratio of H2 to H is 0.02-0.13; and / or H2 satisfies: 4mm≤H2≤10mm.

[0008] In one embodiment, 4≤dD≤22.

[0009] In one embodiment, the ratio of D to d is 0.15-0.5; and / or, d satisfies: 17 mm≤d≤26 mm; and / or, D satisfies: 4 mm≤D≤13 mm.

[0010] In one embodiment, a portion of the tabs are welded to form a first weld print area, and another portion of the tabs are welded to form a second weld print area, and the first weld print area and the second weld print area are spaced apart.

[0011] In one embodiment, the core pack includes a first core pack and a second core pack connected in parallel, and the battery includes a connecting piece, one end of which is connected to the pole lug of the first core pack, and the other end of which is connected to the pole lug of the second core pack.

[0012] In a second aspect, an embodiment of the present invention provides a battery, comprising: a shell; a core pack disposed in the shell, and the core pack is configured as the core pack described above.

[0013] In a third aspect, an embodiment of the present invention provides a battery pack, comprising a box and a plurality of batteries, wherein the plurality of batteries are arranged in the box, and the batteries are arranged as the above-mentioned batteries.

[0014] Beneficial effects of the embodiments of the present invention:

[0015] In an embodiment of the present invention, by controlling the height H1 of the multiple tabs of the core package after folding, the thickness d of the core package, the height H2 of the welding mark area of ​​the tab, and the distance D between the welding mark area and one side of the core package, the following conditions are satisfied: 0.42≤arctan((H1-H2) / (dD)) / arctan((H1-H2) / D)≤1. By performing a tensile test on the tabs of the core package, it is found that the tabs of the core package meet the tensile requirements. By performing a drop test on the battery composed of the core package, it is found that the battery meets the drop test requirements. This allows the battery to improve its safety performance while improving the welding strength of the tabs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 is a top view of a stacked single pole piece assembly unit provided by an embodiment of the present invention;

[0018] Figure 2 yes Figure 1 A partial enlarged view of

[0019] Figure 3 is a side view of a core package provided by one embodiment of the present invention;

[0020] Figure 4 is a front view of a core package provided by an embodiment of the present invention;

[0021] Figure 5 is a front view of two core packages connected according to an embodiment of the present invention;

[0022] Figure 6 is a side view of two core packages connected according to an embodiment of the present invention;

[0023] Figure Number:

[0024] 100, core package; 101, first core package; 102, second core package; 110, side surface;

[0025] 1. Pole piece assembly; 10. Pole piece; 11. Positive pole piece; 12. Negative pole piece; 13. Diaphragm;

[0026] 2. Pole ear; 21. Welding area; 211. First welding area; 212. Second welding area; 22. Positive pole ear; 23. Negative pole ear;

[0027] 3. Connecting piece; DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. In the present invention, unless otherwise specified, the directional words used, such as "upper" and "lower", generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the drawings; while "inside" and "outside" refer to the outline of the device.

[0029] An embodiment of the present application provides a battery, the battery comprising a housing assembly and a core pack. The battery may be a cylindrical battery or a square battery.

[0030] The shell assembly of the battery includes a shell and a top cover, and the top cover is welded to the open end of the shell. A pole is also arranged on the top cover, and the pole can be a positive pole or a negative pole or a positive pole and a negative pole.

[0031] like Figures 1 to 3As shown, the core package 100 includes a pole piece assembly 1, and the pole piece assembly 1 includes a plurality of pole piece group units, and the plurality of pole piece group units are combined to form a core package by stacking or winding. Each pole piece group unit includes a positive pole piece 11, a negative pole piece 12 and a diaphragm 13, and the diaphragm 13 is located between the positive pole piece 11 and the negative pole piece 12 and is used to separate the positive pole piece 11 and the negative pole piece 12. Each positive pole piece 11 includes a positive pole ear 22, and each negative pole piece 12 includes a negative pole ear 23. After stacking the plurality of pole piece group units, the plurality of positive pole ears 22 are folded and connected as a whole by ultrasonic welding, and the plurality of negative pole ears 23 are connected as a whole by ultrasonic welding. Among them, a plurality of positive pole ears 22 or a plurality of negative pole ears 23 are welded to form a weld mark area 21.

[0032] like Figure 1 and Figure 2 As shown, the size of each positive electrode sheet 11 is smaller than the size of each negative electrode sheet 12 and smaller than the size of the separator 13. In a specific implementation, taking a square battery as an example, each positive electrode sheet 11, each negative electrode sheet 12 and each separator 13 are all set to be square, wherein the length difference L1 between each negative electrode sheet 12 and each positive electrode sheet 11 is 0.5mm-1.5mm, and the width difference w1 between each negative electrode sheet 12 and each positive electrode sheet 11 is 0.5mm-2.5mm. The length difference L2 between each separator 13 and each negative electrode sheet 12 is 0.5mm-1.5mm, and the width difference w2 between each separator 13 and each negative electrode sheet 12 is 1mm-2mm. The size of the separator 13 is larger than the size of the negative electrode sheet 12 and the size of the positive electrode sheet 11, which can effectively isolate the positive electrode sheet 11 and the negative electrode sheet 12, thereby preventing short circuit. Among them, if the size of the positive electrode plate 11 is larger than the size of the negative electrode plate 12, the excess lithium ions in the positive electrode plate 11 will not be able to enter the negative electrode plate 12 when the battery is charged, which will cause the positive electrode lithium ions to be deposited on the surface of the negative electrode plate 12, making the battery cycle performance worse. Setting the size of the negative electrode plate 12 to be larger than the size of the positive electrode plate 11 can effectively improve the surface lithium deposition of the negative electrode plate 12.

[0033] The embodiments of the present application also provide a method for preparing a lithium-ion battery, the method for preparing the battery includes: preparing a positive electrode sheet, preparing a negative electrode sheet, core package assembly, tab welding and lithium-ion battery assembly.

[0034] The method for preparing the positive electrode sheet includes: dispersing the positive electrode active material, the conductive agent, and the binder in a solvent NMP (N-methylpyrrolidone), and stirring evenly to obtain a slurry, coating the slurry on the positive electrode collector, and preparing the positive electrode sheet through drying, cold pressing, die cutting, cutting and other processes, wherein the suitable positive electrode active material includes one or more of lithium iron phosphate, lithium iron manganese phosphate or ternary lithium cobalt oxide. The mass ratio of the positive electrode active material: the mass ratio of the conductive agent: the mass ratio of the binder is (94.5% to 97%): (1.5% to 3%): (1.5% to 2.5%).

[0035] The preparation method of the negative electrode plate includes: dispersing the negative electrode active material, the conductive agent, and the binder in a solvent according to a certain proportion, stirring evenly to obtain a slurry, coating the slurry on the negative electrode collector, and obtaining the negative electrode plate through processes such as drying, cold pressing, die cutting, and cutting.

[0036] The core package assembly method includes: stacking the negative electrode sheet, the diaphragm, the positive electrode sheet and the diaphragm in a reciprocating order, and then hot pressing and shaping.

[0037] Tab welding: The tabs of the core pack are usually stacked with multiple layers of foil. Tab welding is to connect the multiple layers of foil into one by ultrasonic welding. Then the tabs are welded to the battery poles by laser welding, or the tabs are welded to the connecting pieces by laser welding, and then the connecting pieces are electrically connected to the poles.

[0038] Lithium-ion battery assembly: Place the core pack into the shell, weld the cover plate at one end of the shell, inject electrolyte, form, and divide the capacity to complete the battery assembly.

[0039] In the related art, during the ultrasonic welding of multiple tabs, poor welding such as cold welding and leaking welding may occur, thereby affecting the welding effect and welding tension, and further causing the tabs to break and reducing the safety performance of the battery cell.

[0040] In the embodiments of the present application, Figure 3 and Figure 4 As shown, the core package 100 includes two side surfaces 110 opposite to each other along its thickness direction. Figure 3The x direction is shown. The height of the tab after folding is set to H1, the height of the weld mark area 21 formed by welding the multiple tabs 2 is set to H2, the distance between the weld mark area 21 and one side of the core package 100 is D, and the thickness of the core package 100 is d, wherein the design parameters of the core package 100 satisfy the expression 1: 0.42≤arctan((H1-H2) / (dD)) / arctan((H1-H2) / D)≤1. In a specific implementation, the ratio of arctan((H1-H2) / (dD)) / arctan((H1-H2) / D) can be 0.42, 0.45, 0.48, 0.5, 0.52, 0.55, 0.58, 0.6, 0.62, 0.65, 0.68, 0.7, 0.72, 0.75, 0.78, 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95, 0.98, 1.0, or a value between any two of the above values, or a range between any two of the above values.

[0041] The height of the weld print area 21 is the height of the bulge of the weld print area 21 in the direction perpendicular to the plane of the tab. The height H2 of the weld print area 21 is measured by taking the unwelded tab surface as a reference plane and using precision measuring tools, such as a micrometer or a height gauge, to measure the vertical distance from the reference plane to the highest point of the weld print area 21. This distance is the height of the weld print area 21.

[0042] In some embodiments, the design parameters of the core pack 100 satisfy the relationship 2: H1-H2≤d / 2. While improving the welding strength of the tab, by limiting the position of the weld mark area, it is beneficial to improve the volume utilization of the battery, thereby improving the energy density of the battery.

[0043] In the embodiments of the present application, a core package embodiment that satisfies both Expression 1 and Expression 2, as well as a core package comparison example that does not satisfy Expression 1 or Expression 2, are designed, and the core packages of the relevant embodiments and the comparison example are prepared into batteries for performing welding tensile tests on the battery tabs and battery drop tests.

[0044] The embodiment of the present application also provides a method for testing the welding tension of a battery tab, the testing method comprising the following steps:

[0045] 1. Install the sample: Fix one end of the battery tab in the upper fixture of the tensile testing machine, and the other end of the tab in the lower fixture, and make sure that the tab is accurately positioned in the angle of the tensile testing machine, and the clamping force is moderate, so that the tab will not loosen or be damaged;

[0046] 2. Set the test parameters: according to the specifications of the battery tabs and the test requirements, set the loading speed, maximum tensile value and other parameters of the tensile testing machine;

[0047] 3. Conduct the test: Start the tensile testing machine and begin to slowly load the battery's tabs. During the loading process, the tensile testing machine records the changes in the tensile value and the deformation of the tabs in real time. The loading continues until the tab weld area breaks or the set maximum tensile value is reached.

[0048] 4. Repeat the test: Take 10 pcs of batteries for each implementation case or comparison case for verification, record the maximum tensile force value of the battery's pole ear, and calculate the average welding tensile force value of the battery's pole ear in each test case. At the same time, observe whether the weld mark area of ​​the battery's pole ear is torn. If torn, record the corresponding welding tensile force value.

[0049] Among them, the welding tensile force standard of the tab is ≥60N.

[0050] The embodiment of the present application also provides a test method for a battery drop test, the reference standard of the test method is GB31485-2015, and the test method includes:

[0051] 1. When the battery is charged at a constant current of 1C to the specified termination voltage of the battery, it is switched to constant voltage charging until the charging current drops to 0.05C and then stops charging;

[0052] 2. The positive and negative terminals of the battery fall freely downward from a height of 1.2m onto the concrete floor;

[0053] 3. Observe for 1 hour;

[0054] 4. Repeat the test: For each implementation case or comparison case, take 10 pcs of batteries for verification and record the pass rate of the battery drop test.

[0055] The present invention provides six battery embodiments that meet both expression 1 and expression 2 and seven battery comparison examples that do not meet one or both of expression 1 and expression 2 to perform a tension test on the battery tabs and a battery drop test and record the test results.

[0056] The parameters of the batteries of the six embodiments and seven comparative examples as well as the results of the tensile test and the battery drop test are shown in Tables 1 and 2 below.

[0057] Table 1. Test case data Table 1

[0058]

[0059] Table 2. Test case data Table 2

[0060]

[0061] It can be seen from the test data of Example 1, Example 2, Example 3, Example 4, Example 5 and Example 6 in Table 1 and Table 2 that when the above-mentioned design parameters of the core package: the height H1 of the tab 2, the height H2 of the weld print area, the thickness d of the core package, and the distance D between the weld print area 21 and the side 110 of the core package simultaneously satisfy Relationship 1 and Relationship 2, the welding tensile force of the tab 2 of the core package meets the standard, and the drop test pass rate of the battery is 100%.

[0062] It should be noted that the above design parameters of the core pack of Example 2 satisfy Relationships 1 and 2, and there is no risk in the welding tensile test of the core pack's pole lugs and the drop test of the battery, but the height of the weld print area is too high, which leads to a low volume utilization rate inside the battery, thereby affecting the energy density of the battery. The above design parameters of the core pack of Example 3 satisfy Relationships 1 and 2, and there is no risk in the welder tensile test of the core pack's pole lugs and the drop test of the battery, but the thickness d of the core pack is too thick, which will cause the length of the pole lug of the pole piece 10 to be too long, making the volume utilization rate of the battery low, thereby reducing the energy density of the battery.

[0063] It can be seen from the test data of comparative example 1 in Table 1 that when the above-mentioned design parameters of the core package do not satisfy relational expression 1 and relational expression 2, the welding tensile force of the pole ear of the battery cell will not meet the standard, which will lead to a high risk of tearing of the pole ear, and will also lead to the battery drop test not meeting the standard, thereby affecting the safety performance of the battery. It can be seen from the test data of comparative example 3 in Table 1 that when the above-mentioned design parameters of the core package do not satisfy relational expression 2, and the height H2 of the weld print area is too small, the welding tensile force of the pole ear of the battery cell will not meet the standard, which will lead to a high risk of tearing of the pole ear, and will also lead to the battery drop test not meeting the standard, thereby affecting the safety performance of the battery. It should be noted that the above-mentioned design parameters of the battery cell provided in comparative example 2 do not satisfy relational expression 2, but satisfy relational expression 1, and the height H1 of the pole ear after folding is significantly higher, while the height of the pole ear weld print area remains basically unchanged. Although it can pass the test of the welding tensile force of the pole ear and the drop test of the battery, the height H1 of the pole ear after folding is too high, which will lead to too much redundant space inside the battery and cause the volume energy density to be uncompetitive.

[0064] It can be seen from the test data of Comparative Example 4 and Comparative Example 5 in Table 2 that when the design parameters of the core package do not satisfy Expression 1, the battery pole lugs will fail to pass the tensile test and the battery will fail to pass the drop test. It can be seen from the test data of Comparative Example 6 in Table 2 that when the design parameters of the battery cell do not satisfy Expression 1 and Expression 2, the battery pole lugs will fail to pass the tensile test and the battery will fail to pass the drop test. It can be seen from the test data of Comparative Example 7 in Table 2 that although the design parameters of the core package do not satisfy Expression 1 and Expression 2, the tensile test of the battery pole lugs and the drop test of the battery are both passed. After analysis, it is found that the height H1 of the pole lug of Comparative Example 7 is too large, and the volume utilization rate of the core package is low, which is not conducive to improving the energy density of the battery.

[0065] In some embodiments, continue to refer to Figure 3 , the height of the pole piece assembly 1 is H, and the ratio of the height H1 of the pole tab 2 after folding to the height H of the pole piece assembly 1 is 0.02 to 0.13. In one embodiment, the height H of the pole piece assembly 1 is 80 mm to 180 mm, and the height H1 of the pole tab after folding is 14 mm to 22 mm.

[0066] The height H of the pole piece assembly 1 can be designed to be 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, or a value or range between any two of the above values ​​according to the capacity of the battery.

[0067] The inventors have found through research that when the height H1 of the folded tab is less than 14 mm, the area of ​​the weld mark area where the tab is located will be smaller, thereby affecting the welding strength of the tab. When the height of the folded tab is greater than 22 mm, the space utilization rate of the battery will be low, thereby affecting the energy density of the battery. In a specific implementation, H1 can be 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, and a value between any two of the above values, or a range between any two of the above values.

[0068] In a specific implementation, the ratio between H1 and H can be 0.08, 0.10, 0.12, 0.14, 0.16, 0.20, 0.24, 0.28, and a value between any two of the above values, or a range between any two of the above values, which is beneficial for the battery to maintain a higher energy density while enhancing the welding strength of the tab.

[0069] In some embodiments, the ratio of the height H2 of the weld mark area 21 of the pole tab 2 to the height H of the pole piece assembly 1 is 0.02 to 0.13. In one embodiment, the height H of the pole piece assembly 1 is 80 mm to 180 mm, and the height H2 of the weld mark area is 4 mm to 10 mm.

[0070] In a specific implementation, H2 can be 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or a value between any two of the above values, or a range between any two of the above values. The inventors have found through research that when H2 is less than 4mm, the weld print area will be too small, and the welding strength of the tab will be insufficient. When H2 is greater than 10mm, the height H1 of the tab will increase, resulting in a lower space utilization rate of the battery.

[0071] In a specific implementation, the ratio of H2 to H can be 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, and a value between any two of the above values, or a range between any two of the above values, which is beneficial for the battery to maintain a higher energy density while enhancing the welding strength of the tab.

[0072] In some embodiments, dD is 4 mm to 22 mm, wherein the thickness d of the core package is 17 mm to 26 mm, and the distance D between the welding mark area of ​​the tab and the side surface 110 of the core package is 4 mm to 13 mm.

[0073] In a specific implementation, dD can be 4mm, 6mm, 8mm, 10mm, 12mm, 15mm, 17mm, 19mm, 21mm, 22mm, or a value between any two of the above values ​​or a range between any two of the above values. By limiting dD to 4mm to 22mm, the welding strength of the tab can be maintained while maintaining a high volume utilization of the battery.

[0074] In some embodiments, the ratio of the thickness d of the core package to the distance D from the welding mark area of ​​the tab to the side 110 of the core package is 0.15 to 0.5. The thickness d of the core package is 17 mm to 26 mm, and the distance D from the welding mark area of ​​the tab to the side 110 of the core package is 4 mm to 13 mm.

[0075] In a specific embodiment, d can be 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, and a value between any two of the above values, or a range between any two of the above values. The inventors have found through research that when d is set to be less than 17mm, the capacity of the battery will be relatively small, thereby affecting the energy density of the battery. When d is set to be greater than 26mm, the capacity of the battery will be too high, which will make the battery prone to thermal runaway, thereby making the battery more dangerous.

[0076] In a specific embodiment, the distance D between the welding mark area of ​​the pole ear and the side surface 110 of the core package is 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, and a value between any two of the above values ​​or a range between any two of the above values. The inventor found through research that when the distance D between the welding mark area of ​​the pole ear and the side surface 110 of the core package is less than 4mm, for example, the distance D between the left pole ear and the side surface 110 of the core package is less than 4mm, when the thickness of the core package remains unchanged, the length of the right pole ear will be relatively long, which will lead to a smaller coating area of ​​the pole piece 10 corresponding to the right pole ear, thereby reducing the capacity of the battery. When the distance D between the welding mark area of ​​the pole ear and the side surface 110 of the core package is greater than 13mm, it will affect the volume utilization of the battery.

[0077] In a specific implementation, the ratio of the thickness d of the core package to the distance D from the welding mark area of ​​the pole tab to the side surface 110 of the core package is 0.15, 0.18, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, and a value between any two of the above values ​​or a range between any two of the above values. When the ratio of the thickness d of the core package to the distance D from the welding mark area of ​​the pole tab to the side surface 110 of the core package meets the above range, it is beneficial to improve the energy density of the battery while improving the welding strength of the pole tab and improving the safety performance of the battery.

[0078] In some embodiments, a portion of the positive electrode tab 22 or the negative electrode tab 23 is welded to form a first weld print area 211, and another portion of the positive electrode tab 22 or the negative electrode tab 23 is welded to form a second weld print area 212, wherein the first weld print area 211 and the second weld print area 212 are arranged at intervals. The electrode tab has two weld print areas, corresponding to discontinuous welding. If only one weld print area is set, it corresponds to continuously welding all the positive electrode tabs 22 or the negative electrode tabs 23 on the same weld print area. During the continuous welding process, the welding heat will continue to rise, and then it is easy to cause welding explosion, that is, the weld print area breaks or explodes. By setting the weld print area to two or more, corresponding to first welding a portion of the tabs to form the first weld print area 211, and then welding another portion of the tabs to form the second weld print area 212, it can effectively avoid excessive heat generated by continuous welding.

[0079] In some embodiments, Figure 5 and Figure 6As shown, the core package 100 includes a first core package 101 and a second core package 102 connected in parallel, and the battery includes a connecting piece 3, one end of the connecting piece 3 is connected to the pole ear of the first core package 101, and the other end of the connecting piece 3 is connected to the pole ear of the second core package 102, and the two core packages are connected in parallel through the connecting piece 3. The core package of the battery is designed as two core packages connected in parallel, which can enhance the current output capacity of the battery and improve the reliability while increasing the capacity of the battery. For example, when one of the core packages fails, the other core package can continue to work.

[0080] In a specific implementation, Figure 6 As shown, the first core package 101 and the second core package 102 are stacked along the thickness direction thereof, wherein the core-joining direction of the first core package 101 and the second core package 102 is as shown in FIG. Figure 6 In the y direction shown, the distance L between the connecting piece 3 and the side surface 110 of the first core package 101 or the second core package 102 is 7.5 mm to 9.0 mm, which is beneficial to improve the welding strength between the connecting piece 3 and the tabs of the first core package 101 or the second core package 102 and improve the volume utilization of the battery.

[0081] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A core pack for a battery, characterized in that: The core package comprises: A pole piece assembly, the pole piece assembly comprising a plurality of pole pieces, each of the pole pieces comprising a pole ear; Among them, after welding the multiple tabs, a weld mark area is formed, the height of the tab after folding is H1, and the height of the weld mark area is H2; the core package also has two side surfaces opposite to each other along the thickness direction, the distance between the weld mark area and the side surfaces is D, and the thickness of the core package is d, wherein 0.42≤arctan((H1-H2) / (dD)) / arctan((H1-H2) / D)≤1.

2. The core package according to claim 1, characterized in that: H1-H2≤d / 2.

3. The core package according to claim 2, characterized in that: The height of the pole piece assembly is H, and the ratio of H1 to H is 0.08-0.28; and / or H1 satisfies: 14mm≤H1≤22mm.

4. The core package according to claim 2, characterized in that: The height of the pole piece assembly is H, and the ratio of H2 to H is 0.02-0.13; and / or H2 satisfies: 4mm≤H2≤10mm.

5. The core package according to claim 1, characterized in that: 4≤dD≤22.

6. The core package according to claim 5, characterized in that: The ratio between D and d is 0.15 to 0.5; and / or, d satisfies: 17 mm ≤ d ≤ 26 mm; and / or, D satisfies: 4 mm ≤ D ≤ 13 mm.

7. The core package according to claim 1, characterized in that: A portion of the tabs is welded to form a first weld print area, and another portion of the tabs is welded to form a second weld print area, and the first weld print area and the second weld print area are arranged at intervals.

8. The core package according to claim 1, characterized in that: The core pack includes a first core pack and a second core pack connected in parallel, and the battery includes a connecting piece, one end of the connecting piece is connected to the pole lug of the first core pack, and the other end of the connecting piece is connected to the pole lug of the second core pack.

9. A battery, characterized in that: The battery comprises: case; A core package is arranged in the shell, and the core package is set as the core package according to any one of claims 1 to 8.

10. A battery pack, characterized in that: The battery pack comprises: Box; A plurality of batteries are arranged in the box, and the batteries are arranged as described in claim 9.

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