Battery housing and power battery

Abstract

A battery housing and a power battery. The battery housing comprises cover plates and a casing (4). The casing (4) is of a hollow structure having openings, the cover plates are provided with connecting bosses (3), and the connecting bosses (3) are inserted into the openings of the casing (4), so that the cover plates close the casing (4) to form an accommodating cavity (8). A weld seam (9) is formed at the junction of the casing (4) and each cover plate, the weld seam (9) has a weld width n, the thickness of the area of the cover plate in which the connecting boss (3) is provided is a, and a weld width ratio is X=n / a, with a range of 0.16≤X≤1.

Description

Battery casing and power battery

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 24, 2024, with application number 202410096162.3, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, for example, to a battery casing and a power battery. Background Art

[0003] Lithium-ion power batteries generally consist of an internal structure and an external structure. The internal structure primarily consists of the cell electrode group, while the external structure primarily consists of the cell cover and cell casing. The cell casing provides space for the cell electrode group. The cell cover and cell casing are welded together to form an enclosed space, thereby forming a complete lithium-ion battery structure. The cell casing and cell cover are typically laser welded together to form the external structure. The casing has openings on both sides that are welded to the cell cover. Summary of the Invention

[0004] The present application provides a battery casing and a power battery with firm welding, good welding airtightness and high safety in use.

[0005] On the one hand, an embodiment of the present application provides a battery housing, comprising a cover plate and a shell, wherein the shell is a hollow structure with an opening, and the cover plate is provided with a connecting boss, wherein the connecting boss is inserted into the opening of the shell, so that the cover plate closes the shell to form a receiving cavity;

[0006] A weld is provided at the connection between the shell and the cover plate, and the weld includes a weld width dimension n. The thickness dimension a of the cover plate in the area where the connecting boss is provided is, and the weld width ratio is X=n / a. The range of the weld width ratio is: 0.16≤X≤1.

[0007] In some embodiments, the weld further includes a penetration dimension m, the wall thickness dimension of the shell is b, the penetration ratio is Y=m / b, and the range of the penetration ratio is: 1≤Y≤7.5.

[0008] In some embodiments, the thickness dimension a is greater than the weld width dimension n, and the wall thickness dimension b is less than the weld depth dimension m.

[0009] In some embodiments, the size information of the battery housing includes at least one of the following: the size range of the weld width dimension n is: 500 μm ≤ n ≤ 2000 μm, or the size range of the thickness dimension a is: 1.5 mm ≤ a ≤ 3 mm.

[0010] In some embodiments, the size information of the battery housing includes at least one of the following: the size range of the penetration dimension m is: 500 μm ≤ m ≤ 1500 μm, or the size range of the wall thickness dimension b is: 0.2 mm ≤ b ≤ 1.5 mm.

[0011] In some embodiments, after the cover plate is welded to the shell, a first protruding structure is formed on the top surface of the cover plate, and a height dimension C1 of the first protruding structure is in the range of C1<200 microns.

[0012] In some embodiments, after the cover plate is welded to the shell, a second protruding structure is formed on the side surfaces of the cover plate and the shell, and a height dimension C2 of the second protruding structure is in the range of C2<200 microns.

[0013] In some embodiments, a guide slope is provided on a side of the connecting boss facing the housing.

[0014] In some embodiments, the cover plate is connected to the housing by laser welding.

[0015] On the other hand, an embodiment of the present application provides a power battery, which includes a battery casing as described in any one of the above items, and the power battery also includes a battery cell electrode group, which is arranged in the accommodating cavity. The length dimension of the power battery is L, and the size range of the length dimension L is 100 mm ≤ L ≤ 600 mm or 600 mm ≤ L ≤ 1500 mm. The width dimension of the power battery is B, and the size range of the width dimension B is 50 mm ≤ B ≤ 250 mm. The height dimension of the power battery is H, and the size range of the height dimension H is 10 mm ≤ H ≤ 100 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a schematic diagram of the structure of a blade lithium-ion power battery in some implementations of the present application;

[0017] FIG2 is a schematic diagram showing the connection between the positive electrode cover and the shell of the battery housing of a blade lithium-ion power battery in some implementations of the present application;

[0018] FIG3 is a metallographic image of the positive electrode cover and the shell of the battery casing of the blade lithium-ion power battery after welding in some implementations of the present application;

[0019] FIG4 is a top view of a square-shell lithium-ion power battery in some implementations of the present application;

[0020] FIG5 is a cross-sectional view taken along the AA direction in FIG4;

[0021] FIG6 is a schematic diagram showing the connection between the top cover and the shell of a battery housing in a square-shell lithium-ion power battery in some implementations of the present application;

[0022] FIG7 is a metallographic image of the top cover and the shell of the battery casing of a square-shell lithium-ion power battery after welding in some implementations of the present application;

[0023] FIG8 is a table of experimental data of thirteen groups of weld width dimensions n ranging from 500 μm to 2000 μm and weld depth dimensions m ranging from 500 μm to 1500 μm selected in this application;

[0024] FIG9 is a table of test data for twelve groups of weld width dimensions n outside the range of 500 μm to 2000 μm and weld depth dimensions m outside the range of 500 μm to 1500 μm selected in this application;

[0025] FIG10 is a schematic diagram of the external dimensions of a power battery in some embodiments of the present application.

[0026] In the figure: 100, battery cell electrode group; 1, positive electrode cover; 2, negative electrode cover; 3, connecting boss; 31, guide slope; 4, shell; 5, first protrusion structure; 6, second protrusion structure; 7, top cover; 8, accommodating cavity; 9, weld. DETAILED DESCRIPTION

[0027] The present application is described below in conjunction with the accompanying drawings and embodiments. The embodiments described herein are used to explain the present application. For ease of description, only some structures related to the present application are shown in the accompanying drawings.

[0028] In the description of this application, unless otherwise specified or limited, the terms "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal connections between two components or interactions between two components. A person of ordinary skill in the art will understand the meanings of the above terms in this application as appropriate.

[0029] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first feature being in direct contact with the second feature, or may include the first feature being in contact with the second feature through another feature between them instead of being in direct contact. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may indicate that the first feature is at a higher level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may indicate that the first feature is at a lower level than the second feature.

[0030] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are used to refer to positions or locations based on those shown in the accompanying drawings. These terms are intended solely to facilitate description and simplify operation, and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Furthermore, the terms "first" and "second" are used for descriptive purposes only and do not have any special meanings.

[0031] In the related art, the battery cell electrode group is first installed inside the battery cell shell, and then the opening is sealed with a battery cell cover, and the battery cell cover is welded to the opening by laser gap welding. However, during the current sealing welding, there are no constraints on the parameters such as the weld depth and weld width of the battery cell shell and the battery cell cover after welding, which leads to the welding connection between the battery cell cover and the battery cell shell not being strong enough and prone to cracking and damage. Especially when the battery generates gas during the charging and discharging process, the internal air pressure will form shear force at the welding gap, and the weld is prone to cracking. The poor welding airtightness causes the battery to leak, resulting in battery failure and safety accidents.

[0032] In order to ensure that the battery housing has sufficient welding strength and welding airtightness, this embodiment provides a battery housing.

[0033] As shown in Figures 1 to 3, the battery casing includes a cover plate and a shell 4. The shell 4 is a hollow structure with an opening. The cover plate is provided with a connecting boss 3. The connecting boss 3 is inserted into the opening of the shell 4 so that the cover plate closes the shell 4 to form an accommodating cavity 8. A weld 9 is provided at the connection between the shell 4 and the cover plate. The weld 9 includes a weld width dimension n. The thickness dimension of the area where the cover plate is provided with the connecting boss 3 is a. The weld width ratio is X=n / a, and the range of the weld width ratio is: 0.16≤X≤1.

[0034] By providing a connecting boss 3 on the cover plate, when connecting the cover plate and the shell 4, the connecting boss 3 is plugged into the open part of the shell, so that the connection between the cover plate and the shell 4 is more firmly connected and welding is facilitated. In addition, the range of the weld width ratio X composed of the weld width dimension n of the weld seam 9 at the connection between the shell 4 and the cover plate and the thickness dimension a of the area of ​​the cover plate where the connecting boss 3 is provided is set, so that when the weld width ratio range is between 0.16≤X≤1, the battery shell has sufficient welding strength and welding airtightness.

[0035] The structure of the battery shell and the range of the weld width ratio X are limited, and can be used in various types of power batteries. However, in this embodiment, the battery shell is a battery shell of a blade lithium-ion power battery. The positive and negative tabs of the blade lithium-ion power battery are located on both sides of the battery cell. Therefore, the shell 4 is a hollow structure with two open sides, and two cover plates are provided correspondingly, namely the positive cover plate 1 and the negative cover plate 2. The positive cover plate 1 and the negative cover plate 2 are respectively provided at the open positions on both sides of the shell 4. After the cover plate and the shell 4 are welded, the strength and airtightness of the weld are tested by strength testing and helium testing. When the welded cover plate and the shell 4 are subjected to a strength test, a pressure greater than 1.2 megapascals (Mpa) is applied to the welded cover plate and the shell 4. If no air leakage occurs under this condition, it is reversely proved that the weld will only be broken when the pressure inside the cover plate and the shell 4 is much greater than 1.2Mpa, so the welding strength of the weld meets the requirements. When the helium test is performed on the welded cover plate and the shell 4, if the helium test leakage rate after the cover plate and the shell 4 are welded is less than 1×10 -7 Pascal cubic meter per second (Pa·m 3 The helium test refers to the use of a helium mass spectrometer to perform airtightness testing on the battery after the cover plate and the housing 4 are welded.

[0036] Optionally, the weld 9 further includes a penetration dimension m, the wall thickness dimension b of the shell 4, a penetration ratio Y = m / b, and a range of the penetration ratio: 1 ≤ Y ≤ 7.5. By setting the range of the penetration ratio Y, which is formed by the penetration dimension m of the weld 9 at the connection between the shell 4 and the cover plate and the wall thickness dimension b of the shell 4, when the penetration ratio range is between 1 ≤ Y ≤ 7.5, it cooperates with the weld width ratio range of 0.16 ≤ X ≤ 1, so that the battery housing has sufficient welding strength and welding airtightness.

[0037] Optionally, the thickness dimension a is greater than the weld width dimension n, and the wall thickness dimension b is less than the penetration dimension m. By making the thickness dimension a greater than the weld width dimension n, the formation of weld beads during welding is avoided, improving welding yield, avoiding rework, and increasing production costs. By making the penetration dimension m greater than the wall thickness dimension b of the housing 4, the welding between the housing 4 and the cover plate is more thorough, resulting in higher weld strength and airtightness.

[0038] In some embodiments, the weld width dimension n is in the range of 500 micrometers (μm) ≤ n ≤ 2000 micrometers (μm), and / or the thickness dimension a is in the range of 1.5 millimeters (mm) ≤ a ≤ 3 millimeters (mm). For example, the thickness dimension a of the cover plate can be any value between 1.5 mm and 3 mm, or a range defined by any two values ​​within this range, such as 1.5 mm, 2 mm, 2.5 mm, or 3 mm. In this embodiment, the exemplary value of the thickness dimension a of the cover plate is 2 mm.

[0039] When the thickness dimension a is the maximum value of 3mm, since the thickness dimension a needs to be greater than the weld width dimension n, the size range of the weld width dimension n is 500μm≤n≤2000μm, and when the weld width dimension n is 500μm, the weld width ratio is the minimum value of 0.16;

[0040] When the thickness dimension a is the minimum value of 1.5, since the thickness dimension a needs to be greater than the weld width dimension n, the size range of the weld width dimension n is 500μm≤n≤1500μm. When the weld width dimension n is 1500μm, the weld width ratio is the maximum value of 1.

[0041] In some embodiments, the penetration dimension m is in the range of 500 μm ≤ m ≤ 1500 μm, and / or the wall thickness dimension b is in the range of 0.2 mm ≤ b ≤ 1.5 mm. For example, the wall thickness dimension b of the shell 4 can be any value between 0.2 mm and 1.5 mm, or a range determined by any two values ​​within this range, such as 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1.0 mm, or 1.5 mm. In this embodiment, the wall thickness dimension b of the shell 4 is 0.35 mm.

[0042] When the wall thickness dimension b is the maximum value of 1.5mm, since the wall thickness dimension b is smaller than the penetration dimension m, the penetration dimension m can only be 1500μm. At this time, the penetration ratio is the minimum value of 1;

[0043] When the wall thickness dimension b is the minimum value of 0.2 mm, since the wall thickness dimension b is smaller than the penetration dimension m, the size range of the penetration dimension m is 500 μm≤m≤1500 μm. When the penetration dimension m is 1500 μm, the penetration ratio is the maximum value of 7.5.

[0044] Optionally, after the cover plate is welded to the housing 4, a first raised structure 5 is formed on the top surface of the cover plate. The height dimension C1 of the first raised structure 5 is within the range of C1 < 200 μm. Because the high temperature of welding affects the metallographic structure inside the cover plate, the first raised structure 5 is formed on the top of the cover plate. By limiting the height dimension C1 of the first raised structure 5, it is prevented that the insulating protective sheet is warped when it is attached to the top surface of the cover plate, thereby affecting the surface flatness of the battery housing.

[0045] Optionally, after the cover plate and housing 4 are welded, a second raised structure 6 is formed on the side surfaces of the cover plate and housing 4. The height dimension C2 of the second raised structure 6 is within the range of C2 < 200 μm. Because the high temperature of welding affects the metallographic structure inside the cover plate and housing 4, the second raised structure 6 is formed on the side surfaces of the cover plate and housing 4. By limiting the height dimension C2 of the second raised structure 6, it is prevented that the insulating protective sheet attached to the side surfaces of the cover plate and housing 4 will warp, thereby affecting the surface flatness of the battery housing.

[0046] When the weld width n of the weld seam 9 after the cover plate and the shell 4 are welded is in the range of 500 μm ≤ n ≤ 2000 μm, and the weld depth m is in the range of 500 μm ≤ m ≤ 1500 μm, the burst pressure after the cover plate and the shell 4 are welded is greater than 1.2 MPa and the helium test leakage rate is less than 1×10 -7 Pa·m 3 / s, meeting the strength requirements and air tightness requirements after welding, and making the height dimension C1 of the first protruding structure 5 after welding less than 200μm, and the height dimension C2 of the second protruding structure 6 less than 200μm, meeting the flatness requirements after welding.

[0047] As shown in the table in FIG8 , thirteen groups of embodiments in which the weld width n is between 500 μm and 2000 μm and the weld depth m is between 500 μm and 1500 μm are selected for illustration.

[0048] In Example 1, the weld width n is set to 500 μm, and the weld depth m is set to 500 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 114 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 98 μm, which is less than 200 μm, thereby meeting the flatness requirement after welding. Helium test and strength test are carried out after welding. The results show that the leakage rate measured by helium test is 2.1×10 -8 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.26Mpa, which is greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0049] In Example 2, the weld width n is set to 700 μm, and the weld depth m is set to 600 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 136 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 121 μm, which is less than 200 μm, thereby meeting the flatness requirements after welding. Helium testing and strength testing are carried out after welding, and the helium test results show that the actual leakage rate is 3.4×10-9 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.30Mpa greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0050] In Example 3, the weld width n is set to 900 μm, and the weld depth m is set to 700 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 84 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 92 μm, which is less than 200 μm, thereby meeting the flatness requirement after welding. Helium test and strength test are carried out after welding. The results show that the leakage rate measured by helium test is 6.6×10 -8 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.23Mpa, which is greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0051] In Example 4, the weld width n is set to 1100 μm, and the weld depth m is set to 800 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 157 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 123 μm, which is less than 200 μm, thereby meeting the flatness requirements after welding. Helium testing and strength testing are carried out after welding, and the helium test results show that the actual leakage rate is 3.7×10 -9 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.28Mpa, which is greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0052] In Example 5, the weld width n is set to 1300 μm, and the weld depth m is set to 900 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 113 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 169 μm, which is less than 200 μm, thereby meeting the flatness requirement after welding. Helium test and strength test are carried out after welding. The results show that the leakage rate measured by helium test is 2.7×10 -8 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.36Mpa, which is greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0053] In Example 6, the weld width n is set to 1500 μm, and the weld depth m is set to 950 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 125 μm and less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 119 μm and less than 200 μm, thereby meeting the flatness requirements after welding. Helium test and strength test are carried out after welding, and the helium test leak rate is 4.8×10 -9 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.27Mpa, which is greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0054] In Example 7, the weld width n is set to 1700 μm, and the weld depth m is set to 1050 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 107 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 158 μm, which is less than 200 μm, thereby meeting the flatness requirement after welding. Helium test and strength test are carried out after welding. The results show that the leakage rate measured by helium test is 7.7×10 -8 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.34Mpa, which is greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0055] In Example 8, the weld width n is set to 1900 μm, and the weld depth m is set to 1150 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 136 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 147 μm, which is less than 200 μm, thereby meeting the flatness requirements after welding. Helium testing and strength testing are carried out after welding, and the helium test results show that the actual leakage rate is 1.6×10 -8 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.29Mpa, which is greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0056] In Example 9, the weld width n is set to 800 μm, and the weld depth m is set to 1200 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 174 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 153 μm, which is less than 200 μm, thereby meeting the flatness requirement after welding. Helium test and strength test are carried out after welding. The results show that the leakage rate measured by helium test is 5.7×10 -9 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.30Mpa greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0057] In Example 10, the weld width n is set to 1200 μm, and the weld depth m is set to 1250 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 149 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 163 μm, which is less than 200 μm, thereby meeting the flatness requirement after welding. Helium test and strength test are carried out after welding, and the helium test leakage rate is 7.9×10 -9 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.27Mpa, which is greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0058] In Example 11, the weld width n is set to 1400 μm, and the weld depth m is set to 1300 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 122 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 136 μm, which is less than 200 μm, thereby meeting the flatness requirements after welding. Helium testing and strength testing are carried out after welding, and the helium test results show that the actual leakage rate is 6.5×10 -8 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.31Mpa, greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0059] In Example 12, the weld width n is set to 1800 μm, and the weld depth m is set to 1400 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 128 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 115 μm, which is less than 200 μm, thereby meeting the flatness requirement after welding. Helium test and strength test are carried out after welding, and the helium test leakage rate is 3.9×10 -9 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.23Mpa, which is greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0060] In Example 13, the weld width n is set to 2000 μm, and the weld depth m is set to 1500 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 179 μm, which is less than 200 μm, and the height dimension C2 of the second protruding structure 6 is 157 μm, which is less than 200 μm, thereby meeting the flatness requirement after welding. Helium test and strength test are carried out after welding. The results show that the leakage rate measured by helium test is 5.1×10 -8 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, meeting the air tightness requirements after welding, the bursting pressure is 1.33Mpa, which is greater than 1.2Mpa, meeting the welding strength requirements after welding.

[0061] From Examples 1 to 13, it can be seen that when the weld width n of the weld seam 9 after the cover plate and the shell 4 are welded is in the range of 500 μm ≤ n ≤ 2000 μm, and the weld depth m is in the range of 500 μm ≤ m ≤ 1500 μm, the helium test data after the cover plate and the shell 4 are welded are all less than 1×10 -7 Pa·m 3 / s, meeting the airtightness requirements; the battery explosion pressure is greater than 1.2Mpa, meeting the strength requirements; the height dimension C1 of the first protruding structure 5 is less than 200μm; the height dimension C2 of the second protruding structure 6 is less than 200μm; the cover plate and the shell 4 are attached with an insulating protective sheet without warping, and the flatness meets the requirements.

[0062] As shown in the table in Figure 9, in order to more clearly illustrate the influence of the weld width dimension n and the weld depth dimension m on the welding strength, air tightness and surface flatness after welding, twelve groups of comparison examples in which the weld width dimension n is outside the range of 500μm to 2000μm and the weld depth dimension m is outside the range of 500μm to 1500μm are selected as examples. Among them, Comparative Examples 1 to Comparative Examples 6 are those in which the weld width dimension n is less than 500μm and the weld depth dimension m is less than 500μm, while Comparative Examples 7 to Comparative Examples 12 are those in which the weld width dimension n is greater than 2000μm and the weld depth dimension m is greater than 1500μm.

[0063] In Comparative Example 1, the weld width n is set to 50 μm and the weld depth m is set to 80 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 246 μm, which is greater than 200 μm, and the height dimension C2 of the second protruding structure 6 is 235 μm, which is greater than 200 μm. Therefore, the flatness requirement after welding is not met. Helium test and strength test are performed after welding. The results show that the leakage rate measured by helium test is 1.4×10 -9 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, which meets the air tightness requirements after welding, and the bursting pressure is 0.85Mpa, which is less than 1.2Mpa, and does not meet the welding strength requirements after welding.

[0064] In Comparative Example 2, the weld width n was set to 150 μm and the weld depth m was set to 160 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 were welded was 254 μm, which was greater than 200 μm, and the height dimension C2 of the second protruding structure 6 was 237 μm, which was greater than 200 μm. Therefore, the flatness requirement after welding was not met. After welding, helium test and strength test were performed. The results showed that the leakage rate measured by helium test was 1.4×10 -9 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, which meets the air tightness requirements after welding. The bursting pressure is 0.89Mpa, which is less than 1.2Mpa, and does not meet the welding strength requirements after welding.

[0065] In Comparative Example 3, the weld width n is set to 250 μm, and the weld depth m is set to 240 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 243 μm, which is greater than 200 μm, and the height dimension C2 of the second protruding structure 6 is 278 μm, which is greater than 200 μm. Therefore, the flatness requirement after welding is not met. Helium test and strength test are performed after welding. The results show that the leakage rate measured by helium test is 2.7×10 -9 Pa·m3 / s is less than 1×10 -7 Pa·m 3 / s, which meets the air tightness requirements after welding. The bursting pressure is 0.92Mpa, which is less than 1.2Mpa, and does not meet the welding strength requirements after welding.

[0066] In Comparative Example 4, the weld width n was set to 300 μm and the weld depth m was set to 320 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 were welded was 226 μm, which was greater than 200 μm, and the height dimension C2 of the second protruding structure 6 was 251 μm, which was greater than 200 μm. Therefore, the flatness requirement after welding was not met. Helium test and strength test were performed after welding. The results showed that the leakage rate measured by helium test was 9.6×10 -9 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, which meets the air tightness requirements after welding. The bursting pressure is 0.88Mpa, which is less than 1.2Mpa, and does not meet the welding strength requirements after welding.

[0067] In Comparative Example 5, the weld width n is set to 350 μm and the weld depth m is set to 400 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 219 μm, which is greater than 200 μm, and the height dimension C2 of the second protruding structure 6 is 269 μm, which is greater than 200 μm. Therefore, the flatness requirement after welding is not met. Helium test and strength test are performed after welding. The results show that the leakage rate measured by helium test is 6.7×10 -8 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, which meets the air tightness requirements after welding. The bursting pressure is 0.91Mpa, which is less than 1.2Mpa, and does not meet the welding strength requirements after welding.

[0068] In Comparative Example 6, the weld width n is set to 450 μm, and the weld depth m is set to 450 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 are welded is 226 μm, which is greater than 200 μm, and the height dimension C2 of the second protruding structure 6 is 272 μm, which is greater than 200 μm. Therefore, the flatness requirement after welding is not met. Helium test and strength test are performed after welding. The results show that the leakage rate measured by helium test is 3.4×10 -9 Pa·m 3 / s is less than 1×10 -7 Pa·m 3 / s, which meets the air tightness requirements after welding. The bursting pressure is 1.09Mpa, which is less than 1.2Mpa, and does not meet the welding strength requirements after welding.

[0069] From Comparative Examples 1 to 6, it can be seen that when the weld width n of the weld seam 9 after the cover plate and the shell 4 are welded is less than 500 μm and the weld depth m is less than 500 μm, the helium test data after the cover plate and the shell 4 are welded are all less than 1×10 -7 Pa·m 3 / s, meeting the airtightness requirements; however, the battery explosion pressure is less than 1.2Mpa, which does not meet the strength requirements; the height dimension C1 of the first protruding structure 5 is greater than 200μm; the height dimension C2 of the second protruding structure 6 is greater than 200μm; the insulating protection sheet attached to the cover plate and the shell 4 is warped, and the non-planarity does not meet the requirements.

[0070] In Comparative Example 7, the weld width n was set to 2100 μm and the weld depth m was set to 1600 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 were welded was 297 μm, which was greater than 200 μm, and the height dimension C2 of the second protruding structure 6 was 286 μm, which was greater than 200 μm. Therefore, the flatness requirement after welding was not met. Helium test and strength test were performed after welding. The results showed that the leakage rate measured by helium test was 7.7×10 -5 Pa·m 3 / s is greater than 1×10 -7 Pa·m 3 / s, which does not meet the air tightness requirements after welding, and the bursting pressure is 0.75Mpa, which is less than 1.2Mpa, which does not meet the welding strength requirements after welding.

[0071] In Comparative Example 8, the weld width n was set to 2150 μm and the weld depth m was set to 1700 μm. At this time, the height C1 of the first protruding structure 5 formed after the cover plate and the shell 4 were welded was 302 μm, which was greater than 200 μm, and the height C2 of the second protruding structure 6 was 297 μm, which was greater than 200 μm. Therefore, the flatness requirement after welding was not met. Helium testing and strength testing were performed after welding. The results showed that the leakage rate measured by the helium test was 4.9×10 -6 Pa·m 3 / s is greater than 1×10 -7 Pa·m 3 / s, which does not meet the air tightness requirements after welding, and the bursting pressure is 0.67Mpa, which is less than 1.2Mpa, which does not meet the welding strength requirements after welding.

[0072] In Comparative Example 9, the weld width n was set to 2200 μm and the weld depth m was set to 1800 μm. At this time, the height C1 of the first protruding structure 5 formed after the cover plate and the shell 4 were welded was 320 μm, which was greater than 200 μm, and the height C2 of the second protruding structure 6 was 335 μm, which was greater than 200 μm. Therefore, the flatness requirement after welding was not met. After welding, helium testing and strength testing were performed. The results showed that the leakage rate measured by the helium test was 4.6×10 -6 Pa·m 3 / s is greater than 1×10 -7 Pa·m 3 / s, which does not meet the air tightness requirements after welding, and the bursting pressure is 0.78Mpa, which is less than 1.2Mpa, which does not meet the welding strength requirements after welding.

[0073] In Comparative Example 10, the weld width n was set to 2250 μm and the weld depth m was set to 1900 μm. At this time, the height C1 of the first protruding structure 5 formed after the cover plate and the shell 4 were welded was 327 μm, which was greater than 200 μm, and the height C2 of the second protruding structure 6 was 357 μm, which was greater than 200 μm. Therefore, the flatness requirement after welding was not met. After welding, helium testing and strength testing were performed. The results showed that the leakage rate measured by the helium test was 5.7×10 -4 Pa·m 3 / s is greater than 1×10 -7 Pa·m 3 / s, which does not meet the air tightness requirements after welding, and the bursting pressure is 0.56Mpa, which is less than 1.2Mpa, which does not meet the welding strength requirements after welding.

[0074] In Comparative Example 11, the weld width n was set to 2300 μm and the weld depth m was set to 2000 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 were welded was 356 μm, which was greater than 200 μm, and the height dimension C2 of the second protruding structure 6 was 386 μm, which was greater than 200 μm. Therefore, the flatness requirement after welding was not met. Helium test and strength test were performed after welding. The results showed that the leakage rate measured by helium test was 7.2×10 -5 Pa·m 3 / s is greater than 1×10 -7 Pa·m 3 / s, which does not meet the air tightness requirements after welding, and the bursting pressure is 0.88Mpa, which is less than 1.2Mpa, which does not meet the welding strength requirements after welding.

[0075] In Comparative Example 12, the weld width n was set to 2400 μm and the weld depth m was set to 2200 μm. At this time, the height dimension C1 of the first protruding structure 5 formed after the cover plate and the shell 4 were welded was 396 μm, which was greater than 200 μm, and the height dimension C2 of the second protruding structure 6 was 378 μm, which was greater than 200 μm. Therefore, the flatness requirement after welding was not met. Helium test and strength test were performed after welding. The results showed that the leakage rate measured by helium test was 4.9×10 -6 Pa·m 3 / s is greater than 1×10 -7 Pa·m 3 / s, which does not meet the air tightness requirements after welding, and the bursting pressure is 0.64Mpa, which is less than 1.2Mpa, which does not meet the welding strength requirements after welding.

[0076] From Comparative Examples 7 to 12, it can be seen that when the weld width n of the weld seam 9 after the cover plate and the shell 4 are welded is less than 500 μm and the weld depth m is less than 500 μm, the helium test data after the cover plate and the shell 4 are welded are all greater than 1×10 -7 Pa·m 3 / s, which does not meet the air tightness requirements; the battery explosion pressure is less than 1.2Mpa, which does not meet the strength requirements; the height dimension C1 of the first protruding structure 5 is greater than 200μm; the height dimension C2 of the second protruding structure 6 is greater than 200μm; the insulating protection sheet attached to the cover plate and the shell 4 is warped, and the non-planarity does not meet the requirements.

[0077] Optionally, a guide slope 31 is provided on the side of the connecting boss 3 facing the housing 4. By providing the guide slope 31 on the side of the connecting boss 3 facing the housing 4, the cover plate is guided to be plugged into the housing 4, thereby facilitating the assembly of the cover plate and the housing 4 and improving assembly efficiency.

[0078] Optionally, the cover plate is connected to the shell 4 by laser welding. Connecting the cover plate and the shell 4 by laser welding makes the welding have higher welding precision and welding accuracy, thereby improving the yield rate of the battery shell after welding.

[0079] Figures 4 to 7 illustrate an embodiment of a prismatic lithium-ion power battery. Components identical or corresponding to the prismatic lithium-ion power battery embodiment are denoted by reference numerals corresponding to the blade lithium-ion power battery embodiment. For simplicity, only the differences between the two lithium-ion power batteries will be described.

[0080] The difference is that this battery casing is that of a prismatic lithium-ion power battery. The positive and negative tabs of a prismatic lithium-ion power battery are located on the same side of the cell. Therefore, the housing 4 is a hollow structure with a single-side opening and is provided with a corresponding cover plate, in this case a top cover 7. The positive and negative tabs of the cell are connected to the same top cover 7, which is located over the opening of the housing 4. In this embodiment, the dimensional restrictions on the weld width ratio X, weld depth ratio Y, the thickness dimension a of the cover plate area with the connecting boss, the wall thickness dimension b of the housing 4, the weld width dimension n, and the weld depth dimension m apply.

[0081] In some embodiments, a power battery is also provided, which includes a battery casing of any of the above items, and the power battery also includes a cell electrode group 100, and the cell electrode group 100 is arranged in the accommodating cavity 8. The length dimension of the power battery is L, and the size range of the length dimension L is 100mm≤L≤600mm or 600mm≤L≤1500mm. The width dimension of the power battery is B, and the size range of the width dimension B is 50mm≤B≤250mm. The height dimension of the power battery is H, and the size range of the height dimension H is 10mm≤H≤100mm. By applying the above-mentioned battery casing, the power battery can effectively avoid cracking and leakage, which may lead to power battery failure, thereby improving the safety of the power battery. The power battery can be a blade lithium-ion power battery as shown in Figure 1, or it can be a square shell lithium-ion power battery as shown in Figure 4.

[0082] As shown in FIG10 , the figure shows the length dimension L, width dimension B and height dimension H of the power battery in some implementations of the present application.

Claims

1. A battery housing, the battery housing comprising a cover plate and a housing, the housing being a hollow structure with an opening, the cover plate being provided with a connecting boss, the connecting boss being inserted into the opening of the housing so that the cover plate closes the housing to form a receiving cavity; A weld seam is provided at the connection between the housing and the cover plate, the weld seam including a weld width dimension n, the thickness dimension of the area of the cover plate where the connecting boss is provided being a, and the weld width ratio being X = n / a, and the range of the weld width ratio is: 0.16 ≤ X ≤ 1.

2. The battery housing according to claim 1, wherein, The weld seam further includes a penetration depth dimension m, the wall thickness dimension of the housing being b, and the penetration depth ratio being Y = m / b, and the range of the penetration depth ratio is: 1 ≤ Y ≤ 7.

5.

3. The battery housing according to claim 2, wherein, The thickness dimension a is greater than the weld width dimension n, and the wall thickness dimension b is less than the penetration depth dimension m.

4. The battery housing according to claim 3, wherein, The dimensional information of the battery housing includes at least one of the following: the dimensional range of the weld width dimension n is: 500 microns ≤ n ≤ 2000 microns, or, the dimensional range of the thickness dimension a is: 1.5 mm ≤ a ≤ 3 mm.

5. The battery housing according to claim 3, wherein, The dimensional information of the battery housing includes at least one of the following: the dimensional range of the penetration depth dimension m is: 500 microns ≤ m ≤ 1500 microns, or, the dimensional range of the wall thickness dimension b is: 0.2 mm ≤ b ≤ 1.5 mm.

6. The battery housing according to claim 1, wherein, After the cover plate is welded to the housing, a first convex structure is formed on the top surface of the cover plate, and the dimensional range of the height dimension C1 of the first convex structure is: C1 < 200 microns.

7. The battery housing according to claim 1, wherein, After the cover plate is welded to the housing, a second convex structure is formed on the side surface of the cover plate and the housing, and the dimensional range of the height dimension C2 of the second convex structure is: C2 < 200 microns.

8. The battery housing according to claim 1, wherein, A guiding inclined surface is provided on the side of the connecting boss facing the housing.

9. The battery housing according to claim 1, wherein, The cover plate is connected to the housing by laser welding.

10. A power battery, the power battery comprising the battery housing according to any one of claims 1-9, the power battery further comprising an electrode group of the battery cell, the electrode group of the battery cell being arranged in the receiving cavity, the length dimension of the power battery being L, the dimensional range of the length dimension L being 100 mm ≤ L ≤ 600 mm or 600 mm ≤ L ≤ 1500 mm, the width dimension of the power battery being B, the dimensional range of the width dimension B being 50 mm ≤ B ≤ 250 mm, and the height dimension of the power battery being H, the dimensional range of the height dimension H being 10 mm ≤ H ≤ 100 mm.

Images