Battery cell casing and battery cell

Abstract

The present invention relates to the field of battery technology, and in particular to a battery cell shell and a battery cell. The battery cell shell comprises: a liquid injection hole is opened in the shell; a cover is welded to the liquid injection hole to form a welding part, and the welding part comprises a connecting section and a bursting section. When the gas pressure inside the battery cell breaks through the cover, part of the bursting section bursts first and then drives the bursting section to tear as a whole, so that the cover is connected to the shell via the connecting section when it is opened; the length dimension of the connecting section is Y, and the dimension of the welding part in the length direction of the connecting section is D, 1mm≤Y≤2D / 3mm. The present invention uses the liquid injection hole on the shell as an auxiliary pressure relief channel that can connect the inside and outside of the battery cell when the battery cell is thermally runaway, so that the gas inside the battery cell can be discharged from the liquid injection hole and the hole after the explosion-proof valve is opened, thereby increasing the area of ​​the shell for pressure relief and exhaust without changing the opening area on the shell, so that the pressure inside the battery cell shell is quickly released, ensuring the safety of the battery cell.

Description

Technical Field

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

[0002] Lithium-ion power batteries generally include an internal battery structure and an external battery structure. The internal battery structure mainly includes a battery cell pole group, and the external battery structure mainly includes a battery cell cover and a battery cell shell. The battery cell shell provides a storage space for the battery cell pole group, and the battery cell cover and the battery cell shell are welded together to fix the pole group in the storage space.

[0003] An explosion-proof valve is installed on the battery cover so that when the battery cell loses control and its internal chemical reaction intensifies to produce gas, the explosion-proof valve will break through under a certain pressure to release energy, thereby alleviating the loss of control of the battery cell. Due to the influence of space and battery cell force, the size of the explosion-proof valve is limited, so its layout on the battery cell cover has certain limitations. Therefore, even if the explosion-proof valve is in the open state, the opening area is small, and the pressure inside the battery cell shell cannot be guaranteed to be released quickly. Therefore, thermal runaway due to untimely pressure relief will still bring safety risks. Summary of the invention

[0004] In view of this, the purpose of the present application is to provide a battery cell casing and a battery cell to solve the problem that the existing explosion-proof valve structure is affected by the space and the force on the battery cell, and the opening area of ​​the explosion-proof valve cannot ensure the rapid release of the internal pressure of the battery cell casing. Therefore, even if the explosion-proof valve is opened smoothly, there is still a safety risk.

[0005] A first aspect of the present invention provides a battery cell casing, wherein the battery cell casing comprises:

[0006] A shell having a liquid injection hole, wherein the shell comprises a shell body and a cover plate, and the liquid injection hole is arranged on the shell body and / or the cover plate;

[0007] A cover is welded to the injection hole to form a welding portion between the cover and the hole wall of the injection hole, wherein the welding portion includes a connecting section and a bursting section. When the gas pressure inside the battery cell breaks through the cover, part of the bursting section first bursts and then drives the entire bursting section to tear, so that the cover is connected to the housing via the connecting section when it is opened;

[0008] The length dimension of the connecting section is Y, the dimension of the welding portion in the length direction of the connecting section is D, and 1mm≤Y≤2D / 3mm.

[0009] Preferably, the size of the melt width w1 of the blasting section is smaller than the size of the melt width w2 of the connecting section;

[0010] And / or, the melting depth h1 of the blasting section is smaller than the melting depth h2 of the connecting section.

[0011] Preferably, the size of the melt width w1 of the blasting section is w1=0.5mm~0.7mm;

[0012] And / or, the melting depth h1 of the blasting section is h1=0.5mm~0.7mm.

[0013] Preferably, the size of the weld width w2 of the connecting section is w2 ≥ 0.8 mm;

[0014] And / or, the fusion depth h2 of the connecting section is 0.8 mm ≤ h2 ≤ (t-0.3) mm, t is the thickness of the portion of the housing where the injection hole is provided, and 1 mm ≤ t ≤ 5 mm.

[0015] Preferably, a thickness dimension b of the cover in the second direction is ≥ 0.1 mm.

[0016] Preferably, in the second direction, a distance d between a side of the housing facing the outside of the battery cell and the cover is -0.15 mm to 0.15 mm.

[0017] Preferably, a redundant area is formed on the shell and is arranged circumferentially around the injection hole, and the maximum dimension F of the redundant area in the first direction is ≥ (D+w2+2e+0.1) mm, e is the maximum gap between the hole wall of the injection hole and the cover in the first direction, and e=0.05mm~0.95mm.

[0018] Preferably, the edge of the sealing cover is bent to form a flange portion extending toward the outside of the battery cell, and the dimension of the flange portion in the first direction is c≥w2 / 2+0.2 mm.

[0019] Preferably, the dimension of the flange portion in the second direction is a, h2≤a≤5mm.

[0020] A second aspect of the present invention provides a battery cell, comprising the battery cell casing described in any one of the above technical solutions.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] In the battery cell shell of the present invention, the cover is welded to the injection hole to form a welding part between the cover and the hole wall of the injection hole, and the welding part includes a bursting section and a connecting section. When the gas pressure inside the battery cell breaks through the cover, part of the bursting section bursts first and then drives the entire bursting section to tear, so that the cover is connected to the shell through the connecting section when it is opened, so that the injection hole on the shell is used as an auxiliary pressure relief channel that can connect the inside and outside of the battery cell when the battery cell is thermally runaway, so that the gas inside the battery cell can be discharged from the injection hole and the hole after the explosion-proof valve is opened, thereby increasing the area of ​​the shell for pressure relief and exhaust without changing the opening area on the shell, so that the pressure inside the battery cell shell is quickly released to ensure the safety of the battery cell. In addition, it is also limited that the length dimension of the connecting section and the dimension of the welding part in the length direction of the connecting section meet 1mm≤Y≤2D / 3mm, so as to ensure that the cover can be opened smoothly and can be in a connected state with the shell when it is opened, and avoid the situation where the cover falls off and causes short circuit and loss of control.

[0023] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic diagram of the structure of a battery cell casing provided by an embodiment of the present invention;

[0026] Figure 2 for Figure 1 A schematic diagram of the enlarged structure at B in the middle;

[0027] Figure 3 For along Figure 1 The cross-sectional view taken along line AA;

[0028] Figure 4 for Figure 3 Schematic diagram of the enlarged structure at C in the middle;

[0029] Figure 5 A schematic diagram of the structure of a welding portion in a battery cell housing provided by an embodiment of the present invention;

[0030] Figure 6 For along Figure 1 The cross-sectional view of the EE section;

[0031] Figure 7A schematic diagram of the structure of a battery cell provided in an embodiment of the present invention.

[0032] Icons: 10-housing; 11-liquid injection hole; 20-sealing cover; 21-flanged portion; 30-welding portion; 31-blasting section; 32-connecting section; 33-redundant area; 40-sealing plug; 50-insulating part; 60-pressure relief assembly; 70-pole; 80-shell; 81-cover plate; 90-pole group; D1-first direction; D2-second direction. DETAILED DESCRIPTION

[0033] The following specific embodiments are provided to help the reader obtain a comprehensive understanding of the methods, devices and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be apparent. For example, the order of operations described herein is merely an example, and is not limited to the order set forth herein, but in addition to the operations that must occur in a particular order, changes that will be apparent after understanding the disclosure of the present application may be made. In addition, in order to improve clarity and brevity, descriptions of features known in the art may be omitted.

[0034] The features described herein may be implemented in different forms and should not be interpreted as being limited to the examples described herein. Rather, the examples described herein have been provided only to illustrate some of the many possible ways of implementing the methods, devices and / or systems described herein that will be apparent after understanding the disclosure of the present application.

[0035] Throughout the specification, when an element (such as a layer, a region, or a substrate) is described as being “on”, “connected to”, “bound to”, “over”, or “covering” another element, it may be directly “on”, “connected to”, “bound to”, “over”, or “covering” another element, or one or more other elements may be present between them. In contrast, when an element is described as being “directly on”, “directly connected to”, “directly bound to”, “directly over”, or “directly covering” another element, there may be no other elements present between them.

[0036] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0037] Although terms such as "first," "second," and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions are not limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Therefore, without departing from the teachings of the examples described herein, the first member, component, region, layer, or portion referred to may also be referred to as the second member, component, region, layer, or portion.

[0038] For ease of description, spatial relational terms such as "above", "upper", "below", and "lower" may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. Such spatial relational terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, an element described as being "above" or "upper" relative to another element will subsequently be "below" or "lower" relative to the other element. Therefore, the term "above" includes both "above" and "below" orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relational terms used herein will be interpreted accordingly.

[0039] The terms used herein are only used to describe various examples and are not used to limit the present disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "include", "comprise" and "have" list the stated features, quantities, operations, components, elements and / or their combinations that exist, but do not exclude the existence or addition of one or more other features, quantities, operations, components, elements and / or their combinations.

[0040] Variations in the shapes shown in the drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include variations in shapes that occur during manufacturing.

[0041] The features of the examples described herein may be combined in various ways that will be apparent after understanding the disclosure of the present application. In addition, although the examples described herein have various configurations, other configurations are possible as will be apparent after understanding the disclosure of the present application.

[0042] According to a first aspect of the present invention, a battery cell casing is provided, which specifically includes a casing 10 and a cover 20 .

[0043] Hereinafter, a specific structure of the cell case according to the present embodiment will be described.

[0044] In this embodiment, if Figure 1 and Figure 3 As shown, a liquid injection hole 11 is provided on the shell 10, and the shell 10 includes a shell and a cover plate. A receiving cavity for installing the pole group is formed inside the shell, and at least one end of the shell is provided with an opening connected to the receiving cavity. The cover plate is arranged at the opening to close the receiving cavity, thereby forming a sealed shell 10 structure.

[0045] Specifically, the cover plate can be formed into a rectangular or circular plate-like structure. When the cover plate is formed into a rectangular plate-like structure, the length direction of the cover plate is the first direction D1. The injection hole 11 is provided on the shell and / or the cover plate, that is, when the number of the injection hole 11 is one, the injection hole 11 can be opened on the shell or the cover plate; when there are multiple injection holes 11, in the first optional embodiment, all the injection holes 11 are provided on the cover plate, in the second optional embodiment, all the injection holes 11 are provided on the shell, and in the third optional embodiment, the injection holes 11 are provided on both the cover plate and the shell.

[0046] The injection hole 11 is a through hole structure penetrating the shell 10. The injection hole 11 is used to inject electrolyte into the shell from the outside of the battery shell. The injection hole 11 can be a circular or rectangular hole structure as long as it can connect the inside and outside of the battery.

[0047] In this embodiment, if Figure 1 and Figure 3 As shown, a pressure relief assembly 60 is provided on the battery cell housing, and the pressure relief assembly 60 includes an explosion-proof valve and an explosion-proof valve patch. The explosion-proof valve can be opened under a preset pressure, so that the inside and outside of the battery cell are connected to release the pressure inside the battery cell. The explosion-proof valve patch is arranged on the side of the explosion-proof valve facing the outside of the battery cell to protect the explosion-proof valve and prevent the explosion-proof valve from opening prematurely.

[0048] like Figures 1 to 6 As shown, the cover 20 is welded to the injection hole 11 to form a welding portion 30 between the cover 20 and the housing 10. The welding portion 30 is formed by a welding process and can be understood as a weld with a deep penetration and a wide penetration formed by the welding process. The welding portion 30 is formed into a closed annular structure; specifically, as shown in FIG. Figure 2As shown, the welding portion 30 includes a connecting section 32 and a bursting section 31, the fusion depth includes a fusion depth h2 of the connecting section 32 and a fusion depth h1 of the bursting section 31, and the fusion width includes a fusion width w2 of the connecting section 32 and a fusion width w1 of the bursting section 31. When the connecting portion is formed into a circular ring shape, the connecting section 32 and the bursting section 31 are both formed into an arc structure on a plane where a side of the shell 10 where the injection hole 11 is provided is located. The arc-shaped connecting section 32 and the bursting section 31 are connected to form the welding portion 30 of the closed annular structure as described above. The air pressure inside the battery cell can break through the cover 20. When the air pressure inside the battery cell breaks through the cover 20, part of the bursting section 3 1 first explodes (i.e. the explosion section 31 partially cracks so that the cover 20 is separated from the shell 10) and then drives the explosion section 31 to tear as a whole, so that when the cover 20 is opened toward the outside of the battery cell, it is connected to the shell 10 via the connecting section 32. In this way, the injection hole 11 on the shell 10 is used as an auxiliary pressure relief channel that can connect the inside and outside of the battery cell when the battery cell is thermally runaway, so that the gas inside the battery cell can be discharged from the injection hole 11 and the hole after the explosion-proof valve is opened, thereby increasing the area of ​​the shell 10 for pressure relief and exhaust without changing the opening area on the shell 10, so that the pressure inside the battery cell shell is quickly released, ensuring the safety of the battery cell. It should be noted that the process of opening the cover 20 is similar to the opening method of the push-type pull ring on the can, but the push-type pull ring is opened toward the inside of the can, so the opening direction is different.

[0049] Furthermore, in this embodiment, if Figure 2 As shown, the length dimension of the connecting section 32 is Y, and the dimension of the welding portion 30 in the length direction of the connecting section 32 is D, 1mm≤Y≤2D / 3mm, so as to ensure that the cover 20 can be opened smoothly and can be connected with the outer shell 10 when opened, to avoid the cover 20 falling off from the outer shell 10 and overlapping with other positions of the battery pack to cause the battery pack to short-circuit and lose control, and to avoid the size of Y being too large, which makes it difficult to open the cover 20 when opening.

[0050] It should be noted that, in the present embodiment, the length direction of the connecting section 32 is the extension direction of the line between the two end points of the connecting section 32. When the welding portion 30 is formed into a circular ring, the connecting section 32 is an arc-shaped structure on the circular ring-shaped welding portion 30. The length direction of the connecting section 32 is the extension direction of the line between the two end points of the arc-shaped connecting section 32. The dimension of the circular ring-shaped welding portion 30 in the length direction of the connecting section 32 is the diameter dimension of the outer wall of the welding portion 30. In an optional embodiment, the extension direction of the line between the two end points of the connecting section 32 may be the first direction D1 as described above, but is not limited thereto, as long as it can ensure that the cover 20 can be in a connected state with the housing 10 when opened.

[0051] To ensure that the internal pressure of the battery cell increases so that the outer shell 10 and the cover 20 can be separated in the bursting section 31 when the cover 20 is opened and the outer shell 10 and the cover 20 remain connected in the connecting section 32, in this embodiment, the size of the melt width w1 of the bursting section 31 is smaller than the size w2 of the melt width w2 of the connecting section 32; and / or the size of the melt depth h1 of the bursting section 31 is smaller than the size h2 of the melt depth h2 of the connecting section 32.

[0052] In a preferred embodiment, the melt width w1 of the blasting section 31 is w1=0.5mm~0.7mm, and / or the melt depth h1 of the blasting section 31 is h1=0.5mm~0.7mm, so as to ensure that the cover 20 is firmly connected to the shell 10 to avoid leakage of electrolyte when the battery cell is working normally, and ensure that the blasting section 31 is smoothly torn and broken when the internal pressure of the shell reaches a certain level, thereby ensuring that the cover 20 can be stably opened.

[0053] In a preferred embodiment, the weld width w2 of the connecting section 32 is w2≥0.8mm; and / or the weld depth h2 of the connecting section 32 is 0.8mm≤h2≤(t-0.3)mm, t is the thickness of the portion of the outer shell 10 where the injection hole 11 is provided, 1mm≤t≤5mm; if h2 is too small, the connection strength and reliability between the cover 20 and the outer shell 10 will be affected, thereby failing to ensure that the cover 20 can be effectively connected to the outer shell 10 via the connection portion when it is opened; if h2 is too large, the outer shell 10 will be melted through, and even molten beads may easily drip into the battery cell, resulting in an increase in the defective rate of the battery cell; if t is too small, the strength of the outer shell 10 is insufficient, and the battery cell outer shell is easily deformed under force; if t is too large, material is wasted and the weight is too heavy.

[0054] In this embodiment, the second direction D2 is perpendicular to the first direction D1.

[0055] Furthermore, in this embodiment, if Figure 4 As shown, the cover 20 is formed into a sheet structure, and the thickness dimension b of the cover 20 in the second direction D2 is ≥ 0.1 mm, so as to ensure the structural strength of the cover 20 and avoid the situation where the bursting section 31 does not crack but the main body of the cover 20 itself cracks.

[0056] Furthermore, in this embodiment, if Figure 4 As shown, the circumferential edge of the cover 20 is bent to form a flange portion 21 extending toward the outside of the battery cell, and the dimension of the flange portion 21 in the first direction D1 is c≥w2 / 2+0.2mm, thereby ensuring the welding quality of the welding portion 30 and avoiding defects such as welding explosion points.

[0057] In this embodiment, if Figure 4As shown, the dimension of the flange portion 21 in the second direction D2 is a, h2≤a≤5 mm, thereby avoiding the occurrence of melting through and material waste, thus saving costs.

[0058] In addition, in this embodiment, Figure 4 As shown, in the second direction D2 , the distance d between the side of the housing 10 facing the outside of the battery cell and the cover 20 is −0.15 mm to 0.15 mm, thereby improving the welding yield and ensuring the quality of the welding portion 30 .

[0059] In a preferred embodiment, Figure 2 As shown, a redundant area 33 is formed on the shell 10 around the injection hole 11. Except for the cover 20 and the insulating member 50 facing the inside of the battery cell and the sealing plug 40 closing the injection hole 11 as described below, other structures on the battery cell shell are not arranged in the redundant area 33, so as to ensure the quality of the welding part 30 and avoid the yield of the battery cell being reduced due to the influence of the welding process; specifically, the maximum size F of the redundant area 33 in the first direction D1 is ≥ (D + w2 + 2e + 0.1) mm, e is the maximum gap between the hole wall of the injection hole 11 and the cover 20 in the first direction D1, e = 0.05mm ~ 0.95mm, so that the welding yield can be improved and the quality of the welding part 30 can be ensured. Preferably, the injection hole 11 is arranged at the center of the redundant area 33. It should be noted that when the redundant area 33 is formed into a circle, the size F of the redundant area 33 in the first direction D1 is the diameter size of the redundant area 33. The redundant area 33 can also be formed into other shapes other than a circle, such as a polygon.

[0060] It should be noted that the hole wall of the injection hole 11 and the cover 20 can be arranged parallel to each other or at a preset angle to each other, so e is the maximum gap between the hole wall of the injection hole 11 and the cover 20 in the first direction D1.

[0061] In addition, in this embodiment, Figures 1 to 6 As shown, the battery cell housing also includes a pole 70, an insulating member 50 and a sealing plug 40. The injection hole 11 can be formed as a countersunk hole structure. The cover 20 is arranged on the side of the injection hole 11 facing the outside of the battery cell, and the sealing plug 40 is arranged on the side facing the inside of the battery cell. The sealing plug 40 can be made of rubber material to achieve sealing of the injection hole 11 when the battery cell is working normally to avoid the electrolyte inside the battery cell from contacting with the cover 20, thereby avoiding the impact of the electrolyte on the cover 20. When the battery cell fails and the pressure inside the battery cell increases, the sealing plug 40 can be pushed outward. The sealing plug 40 and the air pressure inside the battery cell act together on the cover 20, so that the bursting section 31 of the welding portion 30 explodes under a preset pressure, thereby opening the cover 20 to achieve pressure relief.

[0062] The pole 70 is installed on the shell 10 and connected to the pole ear on the pole group located inside the battery cell. The number of poles 70 on the shell 10 can be one or more; the insulating member 50 is arranged on the shell 10, and there are multiple insulating members 50, wherein some of the insulating members 50 are arranged on the side of the shell 10 facing the inside of the battery cell, and are used to separate the shell 10 from the inside of the battery cell, and some of the insulating members 50 are arranged on the side of the shell 10 facing the outside of the battery cell and are surrounded by the circumferential side wall of the pole 70, and are used to separate the shell 10 and the pole 70 to play an insulating role. The insulating member 50 can be a plastic member.

[0063] In order to verify that the housing 10 of the present invention can better complete the pressure relief work after being assembled with the cover 20, the cover 20 explosion test is carried out on the battery housing with different b, c, e, Y, D, h1, h2, w1 and w2 parameter sizes. The safe opening pressure set in this experiment is 0.6±0.2MPa. The specific experimental parameters are shown in the following table:

[0064]

[0065] Note: "NG" in the table indicates that the bursting test is unqualified, and "OK" indicates that the bursting test is qualified. The bursting pressure of the cover 20 is " / " because the cover 20 cannot be assembled with the injection hole 11 and therefore cannot be tested.

[0066] As can be seen from the above table, in Example 1, the size of the fusion depth h1 of the blasting section 31 is smaller than the limited range of 0.6±0.1 mm, and after the outer shell 10 and the cover 20 are welded, the blasting pressure of the cover 20 is lower than 0.4 MPa, and the test fails; in Example 7, the size of the fusion depth h1 of the blasting section 31 is larger than the limited range of 0.6±0.1 mm, and after the outer shell 10 and the cover 20 are welded, the blasting pressure of the cover 20 is higher than 0.8 MPa, and the test fails.

[0067] In Example 3, the size of the weld width w1 of the blasting section 31 is smaller than the limited range of 0.6±0.1mm. After the outer shell 10 and the cover 20 are welded, the bursting pressure of the cover 20 is lower than 0.4MPa, and the test fails. In Example 8, the size of the weld width w1 of the blasting section 31 is larger than the limited range of 0.6±0.1mm. After the outer shell 10 and the cover 20 are welded, the bursting pressure of the cover 20 is higher than 0.8MPa, and the test fails.

[0068] In Examples 4 and 9, the thickness dimension b of the cover 20 in the second direction D2 is less than 0.1 mm. After the outer shell 10 and the cover 20 are welded, the bursting pressure of the cover 20 is lower than 0.4 MPa, and the test fails. When the appearance of the battery cell outer shell is observed, cracks are found on the surface of the cover 20 instead of exploding from the bursting section 31, and the opening area is small.

[0069] In Example 12, h2 is less than 0.8 mm, which is not within the limited range of 0.8 mm ≤ h2 ≤ (t-0.3) mm. After the outer shell 10 and the cover 20 are welded, the cover 20 splashes during the pressure release and explosion, causing the battery pack to be overlapped by metal, increasing the risk of short circuit and loss of control of the battery pack.

[0070] In Example 13, the weld width w2 of the connecting section 32 is not within the limited range of w2 ≥ 0.8 mm. After the outer shell 10 and the cover 20 are welded, the cover 20 splashes during the pressure release and explosion, causing the battery pack to be overlapped by metal, increasing the risk of short circuit and loss of control of the battery pack.

[0071] In Example 17, the maximum gap e between the hole wall of the liquid injection hole 11 and the cover 20 in the first direction D1 is smaller than the limited range of e=0.05mm~0.95mm, and the cover 20 cannot be installed; in Example 18, the maximum gap e between the hole wall of the liquid injection hole 11 and the cover 20 in the first direction D1 is larger than the limited range of e=0.05mm~0.95mm, and after the outer shell 10 and the cover 20 are welded, the welding part 30 has explosion points and sand hole defects, and fails to detonate normally during stamping, resulting in premature air leakage.

[0072] In Example 19, the dimension c of the flange portion 21 in the first direction D1 does not satisfy the limiting condition of c≥w2 / 2+0.2mm. After the outer shell 10 and the cover 20 are welded, the weld portion 30 has explosion points and sand hole defects, and fails to detonate normally during stamping, resulting in premature air leakage.

[0073] In Example 11, the length dimension Y of the connecting section 32 is less than 1 mm, which does not meet the limiting condition of 1mm≤Y≤2D / 3mm. After the outer shell 10 and the cover 20 are welded, the cover 20 splashes during the pressure release and explosion, causing the battery pack to be overlapped by metal, increasing the risk of short circuit and loss of control of the battery pack. In Example 15, the dimension Y of the connecting section 32 in the length direction of the connecting section 32 exceeds the limiting condition of 1mm≤Y≤2D / 3mm. After the outer shell 10 and the cover 20 are welded, the bursting pressure of the cover 20 is higher than 0.8MPa, and the test fails.

[0074] In Examples 2, 5, 6, 9, 10, 14, 16, 20 and 21, the bursting pressure of the cover 20 is within the set safe opening pressure range of 0.6±0.2MPa, and observation of the appearance of the battery cell casing shows that they all explode from the bursting section 31, and the inspection is qualified, thereby ensuring the safety of the battery cell.

[0075] According to a battery cell shell provided by the present invention, the cover is welded to the injection hole to form a welding part between the cover and the shell, and the welding part includes a bursting section and a connecting section. When the gas pressure inside the battery cell breaks through the cover, part of the bursting section first bursts and then drives the entire bursting section to tear, so that the cover is connected to the shell through the connecting section when it is opened, so that the injection hole on the shell is used as an auxiliary pressure relief channel that can connect the inside and outside of the battery cell when the battery cell is thermally runaway, so that the gas inside the battery cell can be discharged from the injection hole and the hole after the explosion-proof valve is opened, thereby increasing the area of ​​the shell for pressure relief and exhaust without changing the opening area on the shell, so that the pressure inside the battery cell shell is quickly released, ensuring the safety of the battery cell. In addition, it is also limited that the length dimension of the connecting section and the dimension of the welding part in the length direction of the connecting section meet 1mm≤Y≤2D / 3mm, so as to ensure that the cover can be opened smoothly and can be in a connected state with the shell when it is opened, avoiding the situation of short circuit and loss of control caused by the cover falling off.

[0076] A second aspect of the present invention provides a battery cell, comprising the battery cell casing and an electrode group 90 as described above.

[0077] In this embodiment, if Figure 7 As shown, the pole 70 and the pressure relief assembly 60 are both arranged on the cover plate 81, the pole group 90 is assembled in the shell 80, the pole ear on the pole group 90 is welded to the pole 70, and the cover plate 81 is welded to the shell 80, so that the pole group 90 is enclosed in the shell 80 and the cover plate 81 to form a closed cavity. After the cover plate 81, the pole group 90 and the shell 80 are assembled, the electrolyte is injected into the shell 80 through the injection hole on the shell 10, and after completion, the sealing plug 40 is inserted into the injection hole, and finally the cover 20 is welded at the injection hole 11. When the internal pressure of the battery cell fails and increases to the safe opening pressure of the battery cell, the pressure relief assembly 60 and the cover 20 can be opened at the same time, so that the gas inside the battery cell can be discharged through the pressure relief assembly 60 and the injection hole 11, thereby improving the pressure relief efficiency and improving the safety of the battery cell.

[0078] According to a battery cell provided by the present invention, the liquid injection hole serves as an auxiliary pressure relief channel that can connect the inside and outside of the battery cell when the battery cell thermal runaways, so that the gas inside the battery cell can be discharged from the hole after the liquid injection hole and the pressure relief component are opened, thereby increasing the area on the outer shell for pressure relief and exhaust without changing the opening area on the outer shell, so that the pressure inside the battery cell shell is quickly released, ensuring the safe use of the battery cell.

[0079] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A battery cell casing, characterized in that: The battery cell housing comprises: A shell having a liquid injection hole, wherein the shell comprises a shell body and a cover plate, and the liquid injection hole is arranged on the shell body and / or the cover plate; A cover is welded to the injection hole to form a welding portion between the cover and the hole wall of the injection hole, wherein the welding portion includes a connecting section and a bursting section. When the gas pressure inside the battery cell breaks through the cover, part of the bursting section first bursts and then drives the entire bursting section to tear, so that the cover is connected to the housing via the connecting section when it is opened; The connecting section is an arc, the length of the connecting section is Y, and the length of the connecting section is the length of the line between the two end points of the arc; the dimension of the welding portion in the length direction of the connecting section is D, 1mm≤Y≤2D / 3mm, and the length direction of the connecting section is the extension direction of the line between the two end points of the arc; The pressure relief component is arranged on the shell, and the pressure relief component includes an explosion-proof valve and an explosion-proof valve patch.

2. The battery cell casing according to claim 1, characterized in that: The size of the melt width w1 of the blasting section is smaller than the size of the melt width w2 of the connecting section; And / or, the melting depth h1 of the blasting section is smaller than the melting depth h2 of the connecting section.

3. The battery cell casing according to claim 1, characterized in that: The size of the melt width w1 of the blasting section is w1=0.5mm~0.7mm; And / or, the melting depth h1 of the blasting section is h1=0.5mm~0.7mm.

4. The battery cell casing according to claim 1, characterized in that: The size of the weld width w2 of the connecting section is w2 ≥ 0.8 mm; And / or, the fusion depth h2 of the connecting section is 0.8 mm ≤ h2 ≤ (t-0.3) mm, t is the thickness of the portion of the housing where the injection hole is provided, and 1 mm ≤ t ≤ 5 mm.

5. The battery cell casing according to claim 1, characterized in that: The thickness dimension b of the cover in the second direction is ≥0.1 mm, and the second direction is the axial direction of the liquid injection hole.

6. The battery cell casing according to claim 1, characterized in that: In the second direction, the distance d between the side of the housing facing the outside of the battery core and the cover is -0.15 mm to 0.15 mm, and the second direction is the axial direction of the injection hole.

7. The battery cell casing according to claim 4, characterized in that: A redundant area is formed on the shell and is arranged circumferentially around the injection hole. The maximum dimension F of the redundant area in the first direction is ≥ (D+w2+2e+0.1) mm, e is the maximum gap between the hole wall of the injection hole and the cover in the first direction, e=0.05mm~0.95mm, and the first direction is the length direction of the cover plate.

8. The battery cell casing according to claim 4, characterized in that: The edge of the sealing cover is bent to form a flange portion extending toward the outside of the battery cell, and the dimension of the flange portion in a first direction c≥w2 / 2+0.2mm, and the first direction is the length direction of the cover plate.

9. The battery cell casing according to claim 8, characterized in that: The dimension of the flange portion in the second direction is a, h2≤a≤5 mm, and the second direction is the axial direction of the injection hole.

10. A battery cell, characterized in that: A battery cell casing comprising any one of claims 1 to 9.

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