Housing assembly, battery cell, battery pack, and battery device

Abstract

The application relates to the new energy technology field and discloses a shell assembly, a battery monomer, a battery pack and a battery device. The shell assembly comprises a shell, the shell comprises a shell body and a cover plate, the cover plate is welded and fixed with the shell body and forms a first welding line; the shell body comprises a shell main body and a protruding part, the protruding part is arranged on the side of the shell main body facing a containing cavity, the protruding part is arranged on one end of the shell body close to the opening, and the protruding part is arranged in protrusion relative to the shell main body; along the wall thickness direction of the shell body, the size of the protruding part protruding from the shell main body is D mm; a gas hole is formed in the first welding line, along the fusion depth direction of the first welding line, the ratio of the aperture of the gas hole to the maximum fusion depth of the first welding line is A; and the following condition is met: 0.17 <= D / A <= 29. The shell assembly provided by the application guarantees the strength of the first welding line, avoids the cracking of the first welding line, and simultaneously avoids the internal insulation failure of the battery cell.

Description

Technical Field

[0001] This application relates to the field of new energy technology, specifically to a housing component, a battery cell, a battery pack, and a battery device. Background Technology

[0002] The battery casing includes a housing and a cover plate, which are fixed together by welding to encapsulate the battery cell inside the battery casing.

[0003] In related technologies, during battery cycling or when the battery experiences thermal runaway, changes in internal air pressure can cause the weld lines between the casing and the cover plate to crack due to insufficient connection strength, leading to the cover plate flying off. This increases the contact area between the battery cell and the outside environment, posing a safety risk of battery fire and explosion. Summary of the Invention

[0004] In view of this, this application provides a housing assembly, a battery cell, a battery pack, and a battery device to solve the problem that the weld lines between the housing and the cover plate are prone to cracking under pressure.

[0005] In a first aspect, this application provides a housing assembly, including: The housing has a receiving cavity formed inside; the housing includes a housing having an opening at at least one end along a first direction, and a cover plate that closes to the opening, the cover plate being welded to the housing to form a first weld line; The shell includes a shell body and a protrusion. The protrusion is located on the side of the shell body facing the receiving cavity, and the protrusion is located at the end of the shell near the opening. The protrusion protrudes from the shell body by a dimension D mm along the wall thickness direction of the shell. The first weld wire has pores inside, and the ratio of the pore diameter to the maximum weld depth of the first weld wire along the direction of the weld depth is A. It satisfies: 0.17≤D / A≤29.

[0006] Beneficial effects: This embodiment comprehensively controls the ratio A of the pore diameter of the pores along the melting depth direction of the first weld wire to the maximum melting depth of the first weld wire, and the size D mm of the protrusion of the protrusion of the protrusion from the shell body along the wall thickness direction of the shell, so that D / A meets the limited range, ensuring the strength of the first weld wire, avoiding cracking of the first weld wire, and avoiding internal insulation failure of the battery cell. When the D / A ratio is too large, resulting in an excessively large D value and / or an excessively small A value, the protrusion may be too thick or the porosity too low. This can lead to the protrusion on the casing being too close to the battery cell. During the first welding process, the welding heat can easily affect the battery cell, causing the cell diaphragm to shrink and the internal insulation of the battery cell to fail. Alternatively, in order to reduce the ratio of the porosity to the first welding depth, the welding speed may need to be reduced or a laser oscillation mode may be used for welding, resulting in excessively high welding heat input. The cell diaphragm may melt due to overheating, easily causing the internal insulation of the battery cell to fail. Conversely, when the D / A ratio is too small, resulting in an excessively small D value and / or an excessively large A value, the protrusion may be too thin or the porosity too high. This can easily lead to insufficient welding depth or low strength of the first welding line, making it prone to cracking during repeated use and causing leakage or short circuit risks.

[0007] Secondly, this application also provides a battery cell, comprising: As described above, the housing components; The battery cell is housed within the casing assembly.

[0008] Since the battery cell includes the casing assembly and has the same effect as the casing assembly, it will not be elaborated here.

[0009] Thirdly, this application also provides a battery pack, comprising: The housing; and multiple battery cells as described above housed within the housing; The enclosure includes a bottom wall, and individual battery cells are fixedly mounted on the bottom wall.

[0010] Since the battery pack includes individual battery cells and has the same effect as individual battery cells, it will not be elaborated on here.

[0011] Fourthly, this application also provides a battery device, comprising: One or more battery packs as described above.

[0012] Since the battery device includes a battery pack and has the same effect as a battery pack, it will not be described in detail here. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a single battery cell in this application; Figure 2 This is an exploded view of a single battery cell in this application; Figure 3 This is a top view of a single battery cell in this application; Figure 4 for Figure 3 Schematic diagram of section AA; Figure 5 for Figure 4 A magnified view of a portion of the image; Figure 6 This is a partially enlarged view of the shell and cover plate being welded together via the first weld line in this application. Figure 7 This is another enlarged view of the shell and cover plate welded together by the first weld line in this application; Figure 8 This is a partial enlarged view of the shell and cover plate of this application; Figure 9 This is another enlarged view of the housing and cover plate of this application; Figure 10 for Figure 2 Enlarged view of point B in the middle; Figure 11 This is a schematic diagram of the battery device of this application being used in a vehicle; Figure 12 This is an exploded view of the battery pack in this application.

[0015] Explanation of reference numerals in the attached figures: 10. Outer shell; 1. Shell body; 11. Shell body; 12. Protrusion; 121. First protruding end; 122. Second protruding end; 123. Straight section; 124. Transition section; 101. First sidewall; 102. Second sidewall; 103. Transition wall; 109. Shell bottom surface; 13. Second protrusion; 14. Receiving cavity; 2. Cover plate; 21. Body part; 22. Extension part; 201. First end face; 3. First weld line; 31. Porosity; 4. Battery cell; 5. Insulating components; 6. Terminal assembly; 900, Vehicle; 800, Battery unit; 810, Battery pack; 811, Housing; 812, Cover; 813, Battery group; 700, Controller. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0018] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0019] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0020] The battery casing includes a housing and a cover plate, which are fixed together by welding to encapsulate the battery cell inside the battery casing. In related technologies, during battery cycling or in the event of battery thermal runaway, due to changes in internal air pressure, the weld lines between the housing and the cover plate are prone to cracking due to insufficient connection strength, causing the cover plate to fly off, increasing the contact area between the battery cell and the outside environment, and posing a safety risk of battery fire and explosion.

[0021] Research has found that the main reason for cracking of the weld lines between the battery casing and the cover plate is that during the welding process, the high-temperature gases generated cannot be quickly discharged from the weld pool, resulting in porosity inside the weld line and severely reducing its strength. Consequently, when subjected to significant forces, the weld lines between the battery casing and the cover plate are prone to cracking, and there is even a risk of the cover plate detaching, causing severe thermal runaway of the battery and affecting its safety.

[0022] Existing welding processes are difficult to completely eliminate porosity. However, the inventors of this application have discovered through extensive experiments that by optimizing the weld structure design and adjusting welding parameters, the distribution location and size of porosity can be artificially controlled, so that the porosity is distributed in the non-critical load-bearing areas of the weld wire, thereby improving the overall structural strength and reliability of the weld wire.

[0023] To facilitate understanding of the technical solution of this application, the following explanations are provided for several technical terms that may be involved in this application: Battery cell: A battery cell is the basic unit that makes up a battery. It stores chemical energy and converts it into electrical energy in a controllable manner. In recyclable battery cells, the active materials can be reactivated by charging after discharge, allowing them to continue to be used. Battery cells can be further combined into battery packs. A battery pack contains multiple battery cells, the specific number of which can be adjusted according to the actual application scenario and capacity requirements.

[0024] A single battery cell includes a casing, a cell housed inside the casing, and an electrolyte. The casing has at least one positive terminal and at least one negative terminal.

[0025] In this application, the geometry of the battery cell can be square, or, as a variation, cylindrical or other arbitrary shapes.

[0026] Outer shell 10: An enclosure is a component used to provide a space to house the battery cell and other components and isolate them from the outside environment. An enclosure generally includes a housing with an opening at at least one end and a cover plate. The opening of the housing can be closed by the cover plate, sealing and isolating the internal environment of the battery cell from the external environment. The housing and cover plate are fixed together by welding.

[0027] The outer casing is made of at least one of the following materials: copper, iron, aluminum, stainless steel, and aluminum alloy.

[0028] Cell 4: A battery cell is the component in a battery where electrochemical reactions occur; it is the smallest unit in a battery capable of carrying out electrochemical reactions such as charging and discharging. A battery cell typically consists of a positive electrode, a negative electrode, and a separator located between the positive and negative electrodes. Battery cells can be either wound or stacked. The main shapes of battery cells are cylindrical and cuboid.

[0029] A lithium-ion battery cell mainly consists of a positive electrode, a negative electrode, and a separator located between adjacent positive and negative electrode plates.

[0030] Positive electrode tablets: It is one of the core components in a battery that carries the positive electrode active material. During charging, metal ions (such as lithium ions) are released from the positive electrode active material (oxidation reaction), migrate through the electrolyte, and intercalate into the negative electrode. During discharging, metal ions (such as lithium ions in a lithium battery) are released from the negative electrode and intercalated into the positive electrode active material (reduction reaction), thus realizing the storage and release of lithium ions.

[0031] A positive electrode generally includes a positive current collector and a positive active material layer. The positive active material layer is coated on at least one surface of the positive current collector and includes: a positive active material and a conductive agent. The positive active material includes, but is not limited to, at least one of the following: lithium phosphates, lithium transition metal oxides and their respective modified compounds, or other conventional materials that can be used as positive active materials for batteries. These positive active materials can be used alone or in combination. The lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, at least one of lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt aluminum oxides, lithium nickel cobalt manganese oxides, and their modified compounds. Lithium nickel cobalt manganese oxides satisfy the general chemical formula LiNi. x Co y Mn z M f O2, where 0.1 < x < 1, 0.1 < y < 1, 0.1 < z < 1, and x + y + z + f = 1, M is a dopant element, and M includes at least one of Al, Mg, Ti, Zr, B, P, Nb, Ta, W, Zr, and V.

[0032] The positive electrode current collector includes a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The positive electrode current collector can also include a composite current collector, which may include a polymer material substrate and a metal layer. Composite current collectors are formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0033] The positive electrode conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, conductive carbon black (SuperP) etc.), carbon nanotubes, graphene and carbon nanofibers.

[0034] The positive electrode binder includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0035] Negative electrode plate: The device includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The negative electrode current collector may also include a composite current collector, which may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0036] The negative electrode active layer includes the negative electrode active material, conductive components, and binders. The negative electrode active material can be carbon-based materials such as graphite, porous carbon, hard carbon, soft carbon, and mesophase carbon microspheres, or silicon-based materials such as elemental silicon, silicon oxides, silicon-carbon composites, and silicon-ammonia composites. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0037] Diaphragm: A separator is disposed between the positive and negative electrode plates to separate them and prevent short circuits caused by contact. The separator can be at least one of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride. A coating can also be applied to the surface of the separator. The coating can be an inorganic coating and / or an organic coating. The inorganic coating material includes at least one of alumina, silicon oxide, titanium oxide, magnesium oxide, zirconium oxide, and boehmite; the organic coating includes at least one of aramid coating and polyvinylidene fluoride (PVDF) coating.

[0038] Polar ear: The battery cell also includes tabs, which are located on one side of the positive / negative current collector and are either separate from or integrally formed with the current collector. The tabs are electrically connected to the current collector to conduct current through it. When the tabs and current collector are separate, they can be connected by welding. The tabs are made of a highly conductive metal material (such as copper, aluminum, or nickel).

[0039] Electrolytes: The electrolyte is located between the positive and negative electrodes, serving to conduct ions between them. Electrolytes include liquid electrolytes, gel polymer electrolytes, and solid electrolytes; among them, liquid electrolytes refer to electrolytes that are in a liquid state, possessing the function of conducting ions while isolating electrons; liquid electrolytes are composed of chemical substances such as solvents, electrolyte salts, and additives; solvents can be carbonates, carboxylic esters, or ethers, etc.; electrolyte salts can be lithium salts, sodium salts, or zinc salts; additives can be ethylene carbonate, fluoroethylene carbonate, propylene sulfite, ethylene sulfite, etc.

[0040] Pole assembly 6: The terminal assembly is used to electrically connect the electrode assembly (cell) located inside the housing to external devices (adjacent batteries or other electrical equipment) located outside the housing. The battery can discharge to external devices through the cell output terminal (tab) and the terminal assembly, and an external power source can charge the battery through the terminals and the cell output terminal (tab). The terminal assembly can be directly electrically connected to the cell tab, or it can be electrically connected to the tab through an adapter.

[0041] The materials for the pole assembly include, but are not limited to, metals such as copper, aluminum, aluminum alloy, and copper-aluminum alloy.

[0042] The terminal assembly is usually set on the cover plate, which facilitates the manufacturing process and improves manufacturing efficiency. Of course, the terminal assembly can also be set on other surfaces of the housing other than the cover plate.

[0043] Adapter: One end of the adapter is used to electrically connect to the output end (tab) of the battery cell, and the other end is used to electrically connect to the terminal assembly, so that the tab and the terminal form a current conduction.

[0044] The adapter plate is made of at least one of the following conductive metals: aluminum, copper, and aluminum alloy. The specific material of the adapter plate is selected based on the materials of the battery's terminals and tabs.

[0045] Explosion-proof valve: An explosion-proof valve is a component or part that can be actuated to release internal pressure or temperature when the internal pressure or temperature of a battery cell reaches a predetermined threshold.

[0046] During battery use, explosion-proof valves are mainly used to prevent excessive pressure buildup inside the battery, which could cause deformation or explosion, by allowing gas to escape and reducing the internal pressure of the battery in the event of thermal runaway or other situations.

[0047] The materials used for explosion-proof valves are not limited, including but not limited to aluminum, steel, and alloys. The shapes of explosion-proof valves are not limited, such as square, oblong, elliptical, racetrack-shaped, etc. The types of explosion-proof valves are not limited, such as scored explosion-proof valves, where the scores include grooves, which can be formed by stamping or laser etching.

[0048] Explosion-proof valves include integrated explosion-proof valves or split explosion-proof valves. When the explosion-proof valve is an integrated explosion-proof valve, the explosion-proof valve and the shell are an integral structure. When the explosion-proof valve is a split explosion-proof valve, the shell is provided with a through hole. The explosion-proof valve includes an explosion-proof disc, which is welded to the shell to seal the through hole. The explosion-proof disc is made of materials such as aluminum alloy, titanium, iron, stainless steel, and copper.

[0049] Explosion-proof valves are usually mounted on a cover plate, which facilitates manufacturing and reduces costs.

[0050] Insulating protective layer: The battery also includes an insulating protective layer, which is disposed between the cell and the protrusion to insulate the cell from the protrusion. The insulating protective layer can be an integral part of the separator or a separate structure. When it is a separate structure, the insulating protective layer can be bonded to the surface of the cell or fixed to the protrusion. When fixed to the protrusion, the fixing method can include bonding, spraying, etc. The material of the insulating protective layer can include polypropylene, polyimide, polyethylene terephthalate (PET), polyacrylate, silicone, polyurethane, etc. The following describes... Figures 1 to 12 This describes an embodiment of the present application.

[0051] According to embodiments of this application, in one aspect, a housing assembly is provided, comprising: The outer casing 10 has a receiving cavity 14 formed inside it. The outer casing 10 includes a housing 1 with an opening at least one end along a first direction, and a cover plate 2 that covers the opening. The cover plate 2 is welded to the housing 1 to form a first weld line 3. The housing 1 includes a housing body 11 and a protrusion 12. The protrusion 12 is disposed on the side of the housing body 11 facing the receiving cavity 14, and the protrusion 12 is disposed at the end of the housing 1 with an opening. The protrusion 12 protrudes from the housing body 11 by a dimension D mm along the wall thickness direction of the housing 1. A pore 31 is formed inside the first weld line 3. Along the melting depth direction of the first weld line 3, the ratio of the pore diameter of the pore 31 to the maximum melting depth of the first weld line 3 is A. It satisfies: 0.17≤D / A≤29.

[0052] It should be noted that the first direction can specifically be the height direction of the battery. For ease of description, this application further defines the second direction as the width direction of the cover plate 2, which is also the thickness direction of the battery, that is, the arrangement direction of multiple batteries along the thickness direction; the third direction is the length direction of the cover plate 2, which is also the length direction of the battery.

[0053] It should be noted that the direction of the molten depth of the first weld line 3 refers to the direction from the large molten end of the first weld line 3 to the small molten end. In this embodiment, it can specifically be the wall thickness direction of the shell 1, or it can be understood as the direction from the outside of the shell 1 to the inside.

[0054] It should be noted that the surface of the housing 1 facing the receiving cavity 14 is the inner wall surface, and the surface of the housing 1 away from the receiving cavity 14 is the outer wall surface. The protrusion 12 can be provided on the inner wall surface of the housing 1, or the protrusion 12 can be provided on both the inner wall surface and the outer wall surface of the housing 1.

[0055] In this embodiment, a receiving cavity 14 is formed inside the outer shell 10, and the battery cell 4 is disposed in the receiving cavity 14. The outer shell 10 includes a shell 1 and a cover plate 2. The shell 1 has an opening at at least one end along the first direction. For example, the shell 1 may have openings at both ends along the first direction, and the number of cover plates 2 may be two, which correspondingly block the openings at both ends of the shell 1 along the first direction. Alternatively, the shell 1 may have an opening at only one end along the first direction, and the number of cover plates 2 may be one, which blocks the opening.

[0056] In this embodiment, the shell 1 is constructed with a non-uniform wall thickness. Specifically, the shell 1 includes a shell body 11 and a protrusion 12 formed by a portion of the shell body 11 extending along the wall thickness direction of the shell 1. The wall thickness of the area of ​​the shell 1 where the protrusion 12 forms is greater than the thickness of the area of ​​the shell body 11 outside the protrusion 12. The protrusion 12 is located at the end of the shell body 11 near the opening, thereby enhancing the structural strength around the opening. Furthermore, during subsequent welding, the increased thickness of the protrusion 12 can meet the requirements of higher welding power, improving the welding stability between the shell 1 and the cover plate 2, and enhancing the connection strength between the shell 1 and the cover plate 2.

[0057] The cover plate 2 and the shell 1 are welded together near the opening to form the first weld line 3. The first weld line 3 refers to the weld structure formed between the cover plate 2 and the shell 1. The first weld line 3 can be achieved by laser welding. By focusing the laser beam on the interface between the shell 1 and the cover plate 2, the local material melts and solidifies rapidly to form a dense weld structure, thereby achieving a reliable connection between the cover plate 2 and the shell 1.

[0058] The first weld line 3 has pores 31 inside. During the welding process, the high-temperature gas generated during welding cannot be quickly discharged from the weld pool, thus forming pores 31 inside the first weld line 3. The presence of pores 31 weakens the overall density and mechanical continuity of the weld, which will lead to a decrease in weld strength. When the pores are larger, the weld strength attenuation is more significant. Therefore, the size of pores 31 should be controlled as much as possible and their number should be reduced.

[0059] Furthermore, since the cover plate 2 and the housing 1 need to be continuously welded near the opening to ensure sealing and structural strength, the first weld line 3 is arranged in a closed loop around the opening. The extension direction of the first weld line 3 is consistent with the peripheral extension direction of the cover plate 2; that is, the extension direction of the first weld line 3 follows the trajectory of the closed loop weld. It should be noted that along the extension direction of the first weld line 3, there may be multiple spaced pores 31 inside the first weld line 3. The distribution of these pores 31 is not random but highly related to process parameters such as welding speed, laser power, and shielding gas flow rate. Precise control can be achieved by optimizing the combination of these parameters.

[0060] Furthermore, in this embodiment, the aperture of the pore 31 specifically refers to the maximum circumscribed circle diameter of the pore 31 within a cross-section perpendicular to the extension direction of the first weld line 3. Correspondingly, the maximum penetration depth of the first weld line 3 refers to the maximum extension depth of the weld molten zone along the penetration depth direction within that cross-section. Further, when there are multiple pores 31 along the penetration depth direction on a cross-section, the aperture of the pore 31 refers to the sum of the sizes of the multiple pores 31; when there is only one pore along the penetration depth direction on a cross-section, the aperture of the pore 31 refers to the size of the single pore 31.

[0061] To reduce the aperture of pore 31, a slower welding rate is required. That is, a lower welding rate results in a smaller aperture. However, an excessively low welding rate leads to higher welding heat, which can cause the cell separator inside the battery to deform or melt due to heat, potentially leading to insulation failure and posing a safety hazard. Therefore, a dynamic balance needs to be struck between pore control and welding efficiency, taking into account both weld strength and insulation safety.

[0062] Because the separator of the battery cell is located between the positive and negative electrodes to separate them, and after winding or stacking, the separator will at least partially cover the outermost side to prevent the battery cell from directly contacting or short-circuiting with the inner wall of the casing 1. If the welding heat input is too high, the heat will be conducted to the interior through the casing, which can easily cause the separator to shrink locally or even melt, thereby damaging the insulating function of the separator.

[0063] This embodiment comprehensively controls the ratio A of the aperture of the pore 31 along the melting depth direction of the first weld line 3 to the maximum melting depth of the first weld line 3, and the size D mm of the protrusion 12 protruding from the shell body 11 along the wall thickness direction of the shell 1, so that D / A meets the limited range, ensuring the strength of the first weld line 3, avoiding cracking of the first weld line 3, and avoiding internal insulation failure of the battery cell.

[0064] Specifically, by providing a protrusion 12 at the end of the shell body 11 near the opening, the local wall thickness of the shell 1 at the opening is increased, ensuring sufficient forming space for the first welding line 3, guaranteeing the welding strength between the shell 1 and the cover plate 2, and reducing the risk of cracking of the welding line between the shell 1 and the cover plate 2. Along the wall thickness direction of the shell 1, when the protrusion 12 protrudes too small (D mm) from the shell body 11, it cannot provide sufficient molten pool space for the first welding line 3, easily leading to insufficient penetration depth, and consequently, insufficient welding strength between the shell 1 and the cover plate 2. When D mm is too large, the excessively thick protrusion 12 will compress the internal space of the cell, causing the shell 1 and the cell 4 to be closer together, making it easier for welding heat to be conducted to the separator, exacerbating the risk of thermal damage to the separator, and increasing the risk of insulation failure.

[0065] Specifically, along the melting depth direction of the first weld line 3, when the ratio A of the aperture of the pore 31 to the maximum melting depth of the first weld line 3 is too large, the aperture of the pore 31 along the melting depth direction accounts for too high a proportion of the melting depth of the first weld line, and the strength of the first weld line 3 is difficult to guarantee; while when A is too small, although the strength of the weld line can be improved, the welding heat input increases significantly, which can easily cause the diaphragm to melt due to heat, resulting in a decrease in insulation performance or even complete failure, posing a significant safety hazard.

[0066] When A is large, the diameter of the pore 31 along the penetration depth direction is larger than the penetration depth of the first weld wire. To ensure welding strength, the thickness D of the protrusion 12 needs to be appropriately increased. When A is small, a slower welding speed is required to reduce the diameter of the pore 31, which leads to greater welding heat. To avoid the thickness D of the protrusion 12 being too large and compressing the internal space of the battery cell, and to avoid the weld wire being closer to the battery cell and more easily transferring heat, the thickness D of the protrusion 12 needs to be reduced accordingly. The battery provided in this embodiment, through precise control of the synergistic relationship between D / mm and A, when the formula value of D / A is too large, the value of D is too large and / or the value of A is too small, the protrusion is too thick or the proportion of pores is too low, which easily leads to the protrusion 12 of the shell 1 being too close to the cell 4. During the welding process of the first welding line, the welding heat can easily affect the cell, causing the cell separator to shrink and the insulation inside the cell to fail. Alternatively, in order to reduce the proportion of the pore diameter 31 to the melting depth of the first welding line, it is necessary to reduce the welding speed or use a laser oscillation mode for welding, resulting in excessive welding heat input. The cell separator is prone to melting due to overheating, which can easily cause the insulation inside the cell to fail. Conversely, when the formula value of D / A is too small, the value of D is too small and / or the value of A is too large, the protrusion is too thin or the proportion of pores is too high, which can easily lead to insufficient melting depth or low strength of the first welding line 3, which can easily crack during cycle use, causing leakage or short circuit risks. That is, when the ratio of D / A is in the range of 0.17≤D / A≤29, it can ensure that the first welding line 3 has a certain space in the molten pool to guarantee the forming quality, and reduce the erosion of the diaphragm by welding heat to maintain a safe distance between the cell 4 and the shell 1.

[0067] For example, in this embodiment, the D / A value can be 0.17, 0.18, 0.19, 0.21, 0.23, 0.26, 0.29, 0.31, 0.33, 0.35, 0.36, 0.38, 0.41, 0.43, 0.46, 0.49, 0.52, 0.55, 0.58, 0.62, 0.65, 0.69, or 0. 0.73 or 0.77 or 0.81 or 0.85 or 0.90 or 0.95 or 1.02 or 1.08 or 1.15 or 1.20 or 1.27 or 1.34 or 1.41 or 1.49 or 1.57 or 1.65 or 1.73 or 1.82 or 1.91 or 2.01 or 2.12 or 2.24 or 2.37 or 2.51 or 2.66 or 2.82 or 2. 99 or 3.18 or 3.37 or 3.58 or 3.81 or 4.06 or 4.33 or 4.62 or 4.93 or 5.26 or 5.61 or 5.98 or 6.37 or 6.56 or 6.97 or 7.40 or 7.85 or 8.32 or 8.81 or 9.32 or 9.85 or 10.48 or 11.13 or 11.80 or 12.49 or 13.2 0, 13.73, 14.28, 14.94, 15.36, 16.25, 17.16, 18.09, 19.04, 20.01, 20.55, 21.52, 22.51, 23.52, 24.55, 25.60, 26.67, 27.81, or 29.00, etc., or any range formed by any two of the above values.

[0068] As a further preferred option, the value range of D / A is 0.35≤D / A≤14.94.

[0069] When the value of D / A meets the preferred range of 0.35≤D / A≤14.94, it can ensure that the first welding line 3 has sufficient molten pool space and good forming quality, and can also effectively isolate the erosion of the diaphragm by welding heat and maintain a safe distance between the cell 4 and the shell 1.

[0070] For example, when the D / A value satisfies the preferred range of 0.35 ≤ D / A ≤ 14.94, the D / A value can be 0.35, 0.36, 0.37, 0.39, 0.41, 0.43, 0.46, 0.48, 0.51, 0.53, 0.55, 0.57, 0.61, 0.63, 0.65, 0.67, 0.71, 0.73, 0.75, 0.77, 0.81, 0.83, 0.85, 0.87, 0.91, 0.93, 0.95, 0.97, 1.01, 1.03, 1.07, 1.11, 1.15, 1.19, 1.20, or 1.2. 3 or 1.27 or 1.31 or 1.35 or 1.39 or 1.43 or 1.47 or 1.51 or 1.55 or 1.59 or 1.63 or 1.67 or 1.71 or 1.75 or 1.79 or 1.83 or 1.87 or 1.91 or 1.95 or 2.03 or 2.11 or 2.19 or 2.27 or 2.35 or 2.43 or 2.51 or 2.59 or 2.67 or 2.75 or 2.83 or 2.91 or 2.99 or 3.07 or 3.18 or 3.27 or 3.35 or 3.43 or 3.51 or 3.59 or 3.67 or 3.75 or 3.83 or 3.91 or 3.99 or 4.13 Or 4.27 or 4.41 or 4.55 or 4.69 or 4.83 or 4.97 or 5.11 or 5.25 or 5.39 or 5.53 or 5.67 or 5.81 or 5.95 or 6.09 or 6.23 or 6.37 or 6.56 or 6.71 or 6.85 or 6.99 or 7.13 or 7.27 or 7.41 or 7.55 or 7.69 or 7.83 or 7.97 or 8.11 or 8.25 or 8.39 or 8.53 or 8.67 or 8.81 or 8.95 or 9.09 or 9.23 or 9.37 or 9.51 or 9.65 or 9.79 or 9.93 or 10.07 or 10.21 or 10. 35 or 10.48 or 10.63 or 10.77 or 10.91 or 11.05 or 11.19 or 11.33 or 11.47 or 11.61 or 11.75 or 11.89 or 12.03 or 12.17 or 12.31 or 12.45 or 12.59 or 12.73 or 12.87 or 13.01 or 13.15 or 13.29 or 13.43 or 13.57 or 13.73 or 13.87 or 14.01 or 14.15 or 14.29 or 14.43 or 14.57 or 14.71 or 14.85 or 14.94, etc., or any two of the above values ​​forming an interval range.

[0071] In this application, the test method for A is as follows: According to standard GB / T 26955-2011, the diameter of the pores along the weld depth direction of the first weld line in the welding between the battery casing and the cover plate is measured 5 times, and the average value is recorded as a1mm. At the same time, according to GB / T 26955-2011, the weld depth of the first weld at the pore location is measured 5 times, and the average value is recorded as a2mm. The value A is calculated using the formula A=a1 / a2.

[0072] Furthermore, the adjustment method for A is as follows: If the first weld is a laser weld, the welding speed (200~300mm / s) during laser welding can be adjusted. A higher speed results in larger pore sizes and a higher A value, while a lower speed results in smaller pore sizes and a lower A value. Alternatively, laser oscillation (using a figure-eight or elliptical trajectory) can be used for welding, controlling the oscillation amplitude (3~5mm) to adjust the A value. A larger oscillation amplitude results in a smaller A value, and vice versa. When the shell is made of steel, aluminum, titanium, etc., the proportion of trace doping elements in the shell material, such as Mg, Cu, Cr, Fe, Mn, Zn, C, Si, N, etc., can be controlled.

[0073] In this application, the test method for D is as follows: Use a micrometer to measure the dimensions of the non-protruding parts of the shell three times, and record the average value as D1mm. Use a micrometer to measure the dimensions of the protruding parts of the shell three times, and record the average value as D2mm. Calculate the value of D using the formula D=D2-D1.

[0074] In some embodiments, the first weld wire 3 includes a first end 301 and a second end 302 along the weld depth direction. The first end 301 is disposed further away from the receiving cavity 14 than the second end 302. The pore 31 is disposed at a distance from at least one of the first end 301 and the second end 302.

[0075] Combination Figure 6 As shown, the first end 301 of the first weld line 3 along the penetration direction refers to the end near the outer surface of the housing 1, while the second end 302 of the first weld line 3 along the penetration direction points to the end near the side of the receiving cavity 14.

[0076] Since the stress is concentrated at the end of the first weld line 3, which is a weak point in the structural strength, this embodiment sets the pores 31 at intervals from at least one of the first end 301 and the second end 302. That is, the pores 31 avoid the edge areas of the first end 301 and the second end 302 and are concentrated in the middle molten pool area of ​​the first weld line 3, so as to avoid stress concentration at the end and cracking, and ensure the structural strength of the first weld line 3.

[0077] It should be noted that, in order to ensure that the pore 31 is spaced apart from at least one of the first end 301 and the second end 302, during the welding operation, the laser oscillation mode (using a "figure-eight" or "elliptical" trajectory) is used to control the oscillation amplitude, which can adjust the position of the pore. Specifically, the smaller the oscillation amplitude, the closer the pore is to the second end, and the larger the oscillation amplitude, the closer the pore is to the first end. The position of the pore 31 can also be adjusted by adjusting the welding speed. Specifically, the slower the welding speed, the closer the pore is to the first end, and the faster the welding speed, the closer the pore is to the second end.

[0078] In some embodiments, along the melting depth direction, the minimum distance between the pore 31 and the first end 301 is E mm, satisfying E mm ≥ 0.1 mm; And / or, along the melting depth direction, the minimum distance between the pore 31 and the second end 302 is E mm, satisfying E mm ≥ 0.1 mm.

[0079] By limiting the lower limit of E mm, stress superposition caused by the pore 31 being too close to the end of the first weld line 3 is avoided, thus ensuring the structural strength of the first weld line 3.

[0080] Furthermore, along the melting depth direction, the minimum distance E mm between the pore 31 and the first end 301 also satisfies: E mm ≤ 1.9 mm.

[0081] Furthermore, along the melting depth direction, the minimum distance E mm between the pore 31 and the second end 302 also satisfies: E mm ≤ 1.8 mm.

[0082] This design avoids the pores from being biased to one end, which would reduce the strength of one end of the first weld, causing the weld to crack and leak.

[0083] For example, in this embodiment, the minimum distance E mm between the pore 31 and the first end 301 along the melting depth direction can be 0.1 mm, 0.15 mm, 0.2 mm, 0.27 mm, 0.32 mm, 0.38 mm, 0.43 mm, 0.49 mm, 0.54 mm, 0.6 mm, 0.65 mm, 0.71 mm, 0.76 mm, 0.82 mm, 0.87 mm, 0.93 mm, 0.98 mm, 1.04 mm, 1.09 mm, 1.15 mm, 1.2 mm, 1.28 mm, 1.42 mm, 1.65 mm, 1.72 mm, 1.8 mm, 1.83 mm, or 1.9 mm, or it can be a range formed by any two of the above values.

[0084] For example, in this embodiment, the minimum distance E mm between the pore 31 and the second end 302 along the melting depth direction can be 0.1 mm, 0.15 mm, 0.2 mm, 0.27 mm, 0.32 mm, 0.38 mm, 0.43 mm, 0.49 mm, 0.54 mm, 0.6 mm, 0.65 mm, 0.71 mm, 0.76 mm, 0.82 mm, 0.87 mm, 0.93 mm, 0.98 mm, 1.04 mm, 1.09 mm, 1.15 mm, 1.2 mm, 1.28 mm, 1.42 mm, 1.65 mm, 1.72 mm, or 1.8 mm, or it can be a range formed by any two of the above values.

[0085] In some embodiments, the center line of the first end 301 and the second end 302 along the melting depth direction is defined as S. The center line S passes through the midpoint of the line connecting the first end 301 and the second end 302 along the melting depth direction, and the extension direction of the center line S is perpendicular to the melting depth direction; the pore 31 is arranged to coincide with the center line S.

[0086] Combination Figure 6 As shown, the center line S of the first end 301 and the second end 302 along the melting depth direction is the midpoint of the length of the first end 301 and the second end 302 along the melting depth direction.

[0087] Since the strength is highest in the center area of ​​the weld line, by aligning the pores 31 with the center line S, the impact on the welding strength is minimized, thereby ensuring the structural strength of the first weld line 3 and avoiding uneven local stress caused by the pore distribution deviating from the center line S.

[0088] It should be noted that, in order to align the pore 31 with the center line S, during the welding operation, a laser oscillation mode (using a "figure-eight" or "elliptical" trajectory) is employed. Controlling the oscillation amplitude allows adjustment of the pore 31's position. Specifically, a smaller oscillation amplitude results in the pore being closer to the second end, while a larger oscillation amplitude results in the pore being closer to the first end. The position of the pore 31 can also be adjusted by regulating the welding speed; specifically, a slower welding speed results in the pore being closer to the first end, while a faster welding speed results in the pore being closer to the second end.

[0089] In some other embodiments, the center line of the first end 301 and the second end 302 along the melting depth direction is defined as S. The center line S passes through the midpoint of the line connecting the first end 301 and the second end 302 along the melting depth direction, and the extension direction of the center line S is perpendicular to the melting depth direction. The pores 31 are spaced apart from the center line S. The minimum distance between the pores 31 and the center line S along the melting depth direction is F mm, which satisfies 0.05 mm ≤ F mm ≤ 0.95 mm.

[0090] In this embodiment, the pores 31 are spaced apart from the center line S. By limiting the upper limit of the minimum distance F mm between the pores 31 and the center line S along the weld depth direction, the pores 31 are prevented from deviating too far from the center line S, which would weaken the overall structural strength of the weld wire. At the same time, by limiting the lower limit of F mm, the positioning accuracy requirements of the pores 31 are prevented from being too high, which would increase the difficulty of process implementation. This also prevents the pores 31 from being too close to the center line S, which would lead to processing difficulties and a low product yield.

[0091] It should be noted that, in order to space the pores 31 from the centerline S, during the welding operation, a laser oscillation mode (using a "figure-eight" or "elliptical" trajectory) is employed. Controlling the oscillation amplitude allows adjustment of the pore formation position. Specifically, a smaller oscillation amplitude results in the pore being closer to the second end, while a larger oscillation amplitude results in the pore being closer to the first end. The position of the pores 31 can also be adjusted by regulating the welding speed; specifically, a slower welding speed results in the pore being closer to the first end, while a faster welding speed results in the pore being closer to the second end.

[0092] For example, in this embodiment, the value of F mm can be 0.05 mm, 0.07 mm, 0.09 mm, 0.12 mm, 0.14 mm, 0.17 mm, 0.19 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.31 mm, 0.34 mm, 0.37 mm, 0.4 mm, 0.43 mm, 0.46 mm, 0.49 mm, 0.52 mm, 0.55 mm, 0.58 mm, 0.61 mm, 0.64 mm, 0.67 mm, 0.7 mm, 0.74 mm, 0.78 mm, 0.81 mm, 0.85 mm, 0.9 mm, or 0.95 mm, or it can be any range formed by any two of the above values.

[0093] In some embodiments, in one cross section perpendicular to the extension direction of the first weld line 3, there are multiple pores 31, and the multiple pores 31 are arranged along the direction perpendicular to the weld depth.

[0094] Since the first weld line 3 is arranged in a closed loop along the circumference of the opening, and the extension direction of the first weld line 3 is consistent with the peripheral extension direction of the cover plate 2, multiple pores 31 may exist inside the first weld line 3 along the extension direction of the first weld line 3. The claim of multiple pores 31 in this embodiment means that by performing multi-position scanning on the cross-section of the first weld line 3, pores 31 are detected in multiple cross-sections, and the number of pores 31 detected in a certain cross-section is not less than two.

[0095] Combination Figure 7As shown, when there are multiple pores 31, by limiting the arrangement of the multiple pores 31 along the direction perpendicular to the melting depth, it is avoided that the pores 31 are arranged along the melting depth direction, thus preventing the pores 31 from being too close to the first end 301 or the second end 302 of the first weld wire 3. Since the end position is a weak point in structural strength due to stress concentration, the arrangement of pores 31 along the melting depth direction can easily increase the risk of weld wire cracking. Therefore, arranging the pores 31 along the direction perpendicular to the melting depth direction can disperse the pores 31 in the main area of ​​the weld wire, away from the end where stress is concentrated. At the same time, since the heat generation inside the battery is concentrated, when the pores 31 are arranged along the melting depth direction, some pores 31 will be closer to the receiving cavity 14 side, increasing the risk of weld wire cracking.

[0096] In some embodiments, the cross-sectional shape of the pore 31 is circular or elliptical in one of the cross-sections perpendicular to the extension direction of the first weld line 3.

[0097] When the cross-sectional shape of the pore 31 is circular or elliptical, compared with irregularly shaped pores, circular or elliptical pores are easier to form stably during laser welding. The smaller the influence of pore 31 on strength, the more uniform the stress distribution, which is beneficial to ensuring the structural strength of the first weld line 3.

[0098] In some embodiments, the ratio of the maximum diameter of a single pore 31 to the minimum diameter of a single pore 31 ranges from 1 to 3.

[0099] When the cross-sectional shape of the pore 31 is circular or elliptical, by limiting the range of the ratio between the maximum diameter of a single pore 31 and the minimum diameter of a single pore 31, the diameter difference of multiple pores 31 is avoided to prevent local stress concentration or the formation of interconnected defects due to the large size difference.

[0100] In some embodiments, the pore diameter of the pore 31 is A1 mm, satisfying 0.1 mm ≤ A1 mm ≤ 0.9 mm.

[0101] By limiting the upper limit of the aperture A1 mm of the pore 31, we can avoid the effective bearing area of ​​the first welding line 3 being significantly reduced due to the excessively large aperture, which would cause local stress concentration and reduce the structural strength of the first welding line 3. At the same time, by limiting the lower limit of the aperture A1 mm of the pore 31, we can prevent the welding heat from being too large due to the aperture of the pore 31 being too small, which could easily cause the separator inside the battery to deform or melt due to heat, thus leading to insulation failure and posing a certain safety hazard.

[0102] For example, in this embodiment, the value of A1 mm can be 0.1 mm, 0.2 mm, 0.35 mm, 0.45 mm, 0.55 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.85 mm, or 0.9 mm, or it can be any range formed by any two of the above values.

[0103] In some embodiments, in one cross section perpendicular to the extension direction of the first weld line 3, there are multiple pores 31, the minimum spacing between adjacent pores 31 is G mm, satisfying 0.05 mm ≤ G mm ≤ 1.5 mm; and the diameter of a single pore 31 is A2 mm, satisfying 0.1 mm ≤ A2 mm ≤ 0.7 mm.

[0104] When there are multiple pores 31, by limiting the upper limit of the minimum spacing G mm between adjacent pores 31, we can avoid the pores from being too sparse due to excessive spacing, which would cause some pores 31 to be too close to the end of the first weld wire 3, thus exacerbating the risk of stress concentration. At the same time, by limiting the lower limit of G mm, we can prevent the pores 31 from interfering with each other due to excessive spacing, which would easily cause the pores 31 to connect and form larger defects, thus weakening the overall load-bearing capacity of the weld wire.

[0105] At the same time, by limiting the upper limit of the aperture A1 mm of a single pore 31, the effective bearing area of ​​the first welding line 3 is significantly reduced due to the excessively large aperture, which can lead to local stress concentration and reduce the structural strength of the first welding line 3. Meanwhile, by limiting the lower limit of the aperture A1 mm of a single pore 31, the welding heat is prevented from being too large due to the aperture of the pore 31, which could easily cause the separator inside the battery to deform or melt due to heat, leading to insulation failure and posing a certain safety hazard.

[0106] For example, in this embodiment, the value of G mm can be 0.05 mm, 0.2 mm, 0.35 mm, 0.55 mm, 0.7 mm, 0.85 mm, 1 mm, 1.15 mm, 1.35 mm, or 1.5 mm, or it can be any range formed by any two of the above values.

[0107] For example, in this embodiment, the value of A2 mm can be 0.1 mm, 0.15 mm, 0.22 mm, 0.3 mm, 0.38 mm, 0.45 mm, 0.52 mm, 0.6 mm, 0.65 mm, or 0.7 mm, or it can be any range formed by any two of the above values.

[0108] In some embodiments, in one cross section perpendicular to the extension direction of the first weld line 3, the total area of ​​the pores 31 is S1 mm², and the total area of ​​the first weld line 3 in that cross section is S2 mm², satisfying 0.1% ≤ S1 / S2 ≤ 6%.

[0109] By limiting the upper limit of the S1 / S2 ratio, the total area of ​​pores is prevented from being too high, which would significantly weaken the load-bearing capacity of the first welding line 3 section. By limiting the lower limit of the S1 / S2 ratio, the excessive heat concentration during the welding process caused by the small total area of ​​pores is avoided, which would exacerbate the risk of thermal damage to the separator, causing the separator inside the battery to deform or melt due to heat, and thus lead to insulation failure.

[0110] S1mm² and S2mm² can be measured according to standard ISO13919-2:2012.

[0111] For example, in this embodiment, the value of S1 / S2 can be 0.1% or 0.2% or 0.35% or 0.5% or 0.7% or 0.9% or 1.1% or 1.3% or 1.5% or 1.75% or 2% or 2.2% or 2.4% or 2.6% or 2.8% or 3% or 3.25% or 3.5% or 3.7% or 3.9% or 4.1% or 4.35% or 4.6% or 4.85% or 5.1% or 5.3% or 5.5% or 5.75% or 5.9% or 6%, etc., or it can be any range formed by any two of the above values.

[0112] As a further preferred option, the range of S1 / S2 satisfies 0.1%≤S1 / S2≤3%.

[0113] For example, when the range of S1 / S2 satisfies the preferred range of 0.1% ≤ S1 / S2 ≤ 3%, the value of S1 / S2 can be 0.1% or 0.15% or 0.22% or 0.28% or 0.33% or 0.39% or 0.45% or 0.51% or 0.57% or 0.63% or 0.69% or 0.75% or 0.81% or 0.87% or 0.93% or 1% or 1.12% or 1.25% or 1.38% or 1.5% or 1.65% or 1.8% or 1.95% or 2.1% or 2.25% or 2.4% or 2.55% or 2.7% or 2.85% or 3%, etc., or it can be any interval range formed by the above two values.

[0114] In some embodiments, along the first direction, the cover plate 2 includes a first end face 201 near the receiving cavity 14, and the housing 1 includes a bottom surface 109 disposed opposite to the cover plate 2; The minimum distance between the protrusion 12 and the bottom surface 109 of the shell is H1mm, and the minimum distance between the first end face 201 and the bottom surface 109 of the shell is H2mm, satisfying H1mm < H2mm.

[0115] Combination Figure 4As shown, when H1mm < H2mm, that is, the extension length of the protrusion 12 in the first direction is greater than the thickness of the cover plate 2 in the first direction, it can meet the greater welding power requirements in the subsequent welding process, improve the welding stability of the shell 1 and the cover plate 2, and enhance the connection strength between the shell 1 and the cover plate 2. Conversely, when H1mm ≥ H2mm, on the one hand, the extension length of the protrusion 12 in the first direction is insufficient. At this time, the protrusion 12 cannot provide enough margin to meet the greater welding power requirements, which can easily lead to insufficient welding penetration and poor weld formation, affecting the connection reliability of the shell 1 and the cover plate 2; on the other hand, because the cover plate 2 extends excessively into the shell 1, it may squeeze the layout space of the cell 4 or interfere with the internal structural layout, resulting in a decrease in energy density.

[0116] In some embodiments, the cover plate 2 includes a body portion 21 and an extension portion 22 extending from the body portion 21 toward the receiving cavity 14 in a first direction. The extension portion 22 is adapted to be inserted into the housing 1, and in the first direction, the projection of the extension portion 22 onto the plane of the body portion 21 does not coincide with the projection of the protrusion 12 onto the plane of the body portion 21.

[0117] Combination Figure 5 As shown, the cover plate 2 includes two parts, an upper part being the body part 21 and a lower part being the extension part 22. In the assembled state, the body part 21 can fit against the top end face of the housing 1 or extend into the housing 1; while the extension part 22 is embedded inside the housing 1.

[0118] By limiting the projections of the extension 22 and the protrusion 12 in the first direction to not overlap, the protrusion 12 can be prevented from interfering with the installation of the cover plate 2, ensuring that the extension 22 can be smoothly embedded into the inner cavity of the housing 1, while avoiding the cover plate 2 from excessively squeezing the housing 1 and deforming it, thus affecting the welding strength.

[0119] In some embodiments, at least a portion of the protrusion 12 forms a first bonding line 3.

[0120] In one implementation, the starting position of the protrusion 12 along the first direction can be flush with the edge of the opening and extend to the inside of the opening along the first direction; in another implementation, the starting position of the protrusion 12 along the first direction can be spaced apart from the edge of the opening, that is, there is also a third shell part (not shown in the figure) between the protrusion 12 and the edge of the opening. In this case, the wall thickness of the protrusion 12 can still meet the requirement of improving the structural strength of the shell 1.

[0121] In this embodiment, the first weld line 3 is formed by further defining at least a portion of the protrusion 12. That is, the first weld line 3 is located directly on the thickened area of ​​the housing 1, which better ensures the connection strength between the housing 1 and the cover plate 2.

[0122] In some embodiments, along the first direction, the end of the protrusion 12 away from the opening is spaced apart from the first bonding wire 3, and the spacing distance is H mm, satisfying 0.2 mm ≤ H mm ≤ 14.7 mm.

[0123] Combination Figure 5 As shown, since the end of the protrusion 12 furthest from the opening, which is also the transition area between the protrusion 12 and the shell body 11, the material thickness of the shell 1 is reduced at this point, making it prone to stress concentration and resulting in relatively weak structural strength. Because the welded area between the shell 1 and the cover plate 2 will recrystallize after welding, if the first weld line 3 is too close to the junction of the protrusion 12 and the shell body 11, a heat-affected zone will form at the edge of the first weld line 3. The hardness of the heat-affected zone is weaker than that of the shell 1, leading to a greater risk of fracture at the junction and thus exacerbating the risk of structural failure.

[0124] By limiting the lower limit of H mm, the weld can be kept away from the stress concentration area, ensuring the connection strength between the shell 1 and the cover plate 2. At the same time, by limiting the upper limit of H mm, the protrusion 12 can be prevented from extending excessively and encroaching on the installation space of the cell 4, thus balancing structural strength and battery energy density.

[0125] For example, in this embodiment, the value of H mm can be 0.2 mm, 0.4 mm, 0.7 mm, 1 mm, 1.3 mm, 1.6 mm, 1.9 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3.1 mm, 3.5 mm, 3.9 mm, 4.3 mm, 4.7 mm, 5.1 mm, 5.5 mm, 5.9 mm, 6.3 mm, 6.7 mm, 7.1 mm, 7.6 mm, 8.1 mm, 8.6 mm, 9.1 mm, 9.6 mm, 10.1 mm, 10.7 mm, 12 mm, or 14.7 mm, or it can be any range formed by any two of the above values.

[0126] The penetration depth of the first weld line 3 ranges from 0.3 mm to 2 mm. For example, the penetration depth of the first weld line 3 can be 0.3 mm, 0.5 mm, 0.75 mm, 1 mm, 1.2 mm, 1.45 mm, 1.6 mm, 1.75 mm, 1.9 mm, or 2 mm, or it can be any range formed by any two of the above values.

[0127] The length of the protrusion 12 in the first direction ranges from 0.1 mm to 15 mm. For example, the length of the protrusion 12 in the first direction can be 0.1 mm, 0.3 mm, 0.6 mm, 0.9 mm, 1.5 mm, 2.2 mm, 3 mm, 4 mm, 5.5 mm, 7 mm, 8.5 mm, 9.8 mm, 11 mm, 12.3 mm, 13.5 mm, 14.2 mm, 14.7 mm, or 15 mm, or it can be a range formed by any two of the above values.

[0128] In some embodiments, the ratio of the size of the protrusion 12 to the size of the shell body 11 along the first direction is 0.35 to 3.2.

[0129] By limiting the lower limit of the ratio of the size of the protrusion 12 along the first direction to the size of the shell body 11, it can be ensured that the shell 1 has a sufficiently thickened area to guarantee the structural strength of the shell 1. At the same time, it avoids the welded area being too close to the junction of the protrusion 12 and the shell body 11 due to the protrusion 12 being too short, thereby aggravating the concentration of thermal stress. And by limiting the upper limit of the ratio of the size of the protrusion 12 along the first direction to the size of the shell body 11, it avoids the protrusion 12 being too long, which would lead to structural redundancy and material waste, and avoid excessively increasing the overall weight of the shell 1.

[0130] For example, in this embodiment, along the first direction, the ratio of the size of the protrusion 12 to the size of the shell body 11 can be 0.35 or 0.52 or 0.71 or 0.89 or 1.07 or 1.25 or 1.43 or 1.61 or 1.79 or 1.97 or 2.15 or 2.33 or 2.51 or 2.69 or 2.87 or 3.05 or 3.13 or 3.2, or it can be a range formed by any two of the above values.

[0131] Furthermore, the size of the protrusion 12 along the first direction ranges from 0.06 mm to 1.5 mm. For example, the size of the protrusion 12 along the first direction can be 0.06 mm, 0.12 mm, 0.18 mm, 0.25 mm, 0.33 mm, 0.4 mm, 0.48 mm, 0.55 mm, 0.63 mm, 0.72 mm, 0.81 mm, 0.9 mm, 1.0 mm, 1.12 mm, 1.25 mm, 1.35 mm, 1.42 mm, or 1.5 mm, or it can be a range formed by any two of the above values.

[0132] The dimensions of the shell body 11 along the first direction range from 0.45 mm to 2.5 mm. For example, the dimensions of the shell body 11 along the first direction can be 0.45 mm, 0.55 mm, 0.68 mm, 0.8 mm, 0.92 mm, 1.05 mm, 1.18 mm, 1.3 mm, 1.42 mm, 1.55 mm, 1.68 mm, 1.8 mm, 1.92 mm, 2.05 mm, 2.18 mm, 2.3 mm, 2.42 mm, or 2.5 mm, or a range formed by any two of the above values.

[0133] In some embodiments, combined with Figure 8 As shown, the housing 1 includes a bottom surface 109 disposed opposite to the cover plate 2; along the first direction, the protrusion 12 includes a first protruding end 121 and a second protruding end 122, the second protruding end 122 being disposed closer to the bottom surface 109 of the housing than the first protruding end 121. Along the wall thickness direction of the shell 1, the first protruding end 121 protrudes from the shell body 11 by a dimension of J1mm, and the second protruding end 122 protrudes from the shell body 11 by a dimension of J2mm, satisfying J2mm < J1mm.

[0134] By adopting a size gradient design, the protrusion 12 gradually tapers from the cover plate 2 side to the shell bottom surface 109 side, which not only ensures the local strength and welding stability of the first protrusion 121 near the weld, but also reduces the material redundancy of the second protrusion 122 far from the weld, reduces the shell weight, and optimizes the overall stiffness distribution.

[0135] In some embodiments, the dimensions of the first protrusion 121 to the second protrusion 122 protruding from the shell body 11 gradually decrease.

[0136] Ensure uniform wall thickness transition to avoid sudden increases in local stress and facilitate processing and forming.

[0137] In some embodiments, the protrusion 12 includes a straight section 123 and a transition section 124, with a first protrusion 121 located on the side of the straight section 123 near the cover plate 2, and a second protrusion 122 located on the side of the transition section 124 near the bottom surface 109 of the shell.

[0138] By forming a transition section 124 between the straight section 123 and the shell body 11, the wall thickness gradually transitions from the straight section 123 to the shell body 11, effectively alleviating stress abrupt changes at the junction, avoiding stress concentration between the protrusion 12 and the shell body 11, and reducing the risk of shell 1 cracking. At the same time, by setting the transition section 124, the weakening effect of the welding heat-affected zone on the structural strength can be reduced.

[0139] In some embodiments, combined with Figure 9As shown, the housing 1 also includes a second protrusion 13. Along the wall thickness direction of the housing 1, the second protrusion 13 is disposed on the side of the housing body 11 away from the protrusion 12, and the second protrusion 13 and the protrusion 12 are disposed opposite to each other along the wall thickness direction of the housing 1.

[0140] By symmetrically setting protrusions 12 and second protrusions 13 on both sides of the shell body 11, a double-sided reinforcement structure is formed. While maintaining the strength of the welding wire at the shell opening, it avoids excessive encroachment on the internal space, prevents the shell 1 from getting closer to the cell 4, and prevents welding heat from being more easily conducted to the diaphragm, thus aggravating the risk of thermal damage to the diaphragm. This is more conducive to reducing the risk of insulation failure.

[0141] In some embodiments, the circumferential extension length of the protrusion 12 around the opening of the housing 1 is L1 mm, and the circumference of the opening of the housing 1 is L2 mm, satisfying 0.1≤L1 / L2≤1.

[0142] By limiting the lower limit of L1 / L2, the protrusion 12 is ensured to have sufficient coverage in the critical area of ​​weld formation, increasing the local wall thickness of the shell 1 at the opening, ensuring sufficient forming space for the first weld line 3, guaranteeing the welding strength between the shell 1 and the cover plate 2, and reducing the risk of weld line cracking between the shell 1 and the cover plate 2. At the same time, by limiting the upper limit of L1 / L2, the size of the opening is prevented from being reduced, thereby preventing the cell 4 from being difficult to insert into the shell and easily scratching the shell 1, resulting in damage to the cell 4; and when the value of L1 / L2 exceeds the upper limit, welding heat is more easily conducted to the diaphragm.

[0143] Since the housing 1 includes a long sidewall and a short sidewall, when the cell 4 expands, the side of the cell 4 that is opposite to the long sidewall deforms more. Therefore, the protrusion 12 is preferentially arranged in the corresponding area of ​​the long sidewall to specifically enhance the rigidity and deformation resistance of the long sidewall.

[0144] The long sidewall is the first sidewall 101 of this embodiment, and the short sidewall is the second sidewall 102 of this embodiment. The area of ​​the first sidewall 101 is larger than the area of ​​the second sidewall 102.

[0145] For example, in this embodiment, the value of L1 / L2 can be 0.1 or 0.15 or 0.21 or 0.27 or 0.32 or 0.38 or 0.43 or 0.48 or 0.53 or 0.58 or 0.63 or 0.68 or 0.72 or 0.77 or 0.83 or 0.89 or 0.95 or 1, etc., or it can be any range formed by any two of the above values.

[0146] Furthermore, since the shell 1 includes a long side wall and a short side wall, wherein the long side wall is the first side wall 101 of this embodiment and the short side wall is the second side wall 102 of this embodiment, the area of ​​the first side wall 101 is larger than the area of ​​the second side wall 102.

[0147] When the protrusion 12 is only provided on the short side wall of the housing 1, it satisfies 0.1≤L1 / L2≤0.3. For example, when the value of L1 / L2 satisfies 0.1≤L1 / L2≤0.3, the value of L1 / L2 can be 0.1 or 0.13 or 0.15 or 0.17 or 0.19 or 0.21 or 0.23 or 0.25 or 0.27 or 0.3, etc., or it can be a range formed by any two of the above values.

[0148] When the protrusion 12 is only provided on the long side wall of the housing 1, it satisfies 0.2≤L1 / L2≤0.91. For example, when the value of L1 / L2 satisfies 0.2≤L1 / L2≤0.91, the value of L1 / L2 can be 0.2 or 0.25 or 0.31 or 0.37 or 0.43 or 0.49 or 0.55 or 0.61 or 0.67 or 0.72 or 0.77 or 0.83 or 0.86 or 0.89 or 0.91, etc., or it can be a range formed by any two of the above values.

[0149] In some embodiments, the housing 1 includes two opposing first sidewalls 101 and two opposing second sidewalls 102, the first sidewalls 101 and the second sidewalls 102 enclosing a rectangular opening; the area of ​​the first sidewall 101 is larger than the area of ​​the second sidewall 102, the first sidewall 101 and the second sidewall 102 are connected by a transition wall 103, and the protrusion 12 is at least partially located in the transition wall 103.

[0150] Combination Figure 10 As shown, by further extending the protrusion 12 to the transition wall 103, the stress concentration at the connection between the first side wall 101 and the transition wall 103 can be effectively relieved, and the reliability of the overall structure under the condition of cell expansion can be improved.

[0151] In this embodiment, the transition wall 103 can be arc-shaped, which can reduce stress concentration while ensuring a smooth transition of the structure.

[0152] In some embodiments, the following conditions are met: 0.05 ≤ A ≤ 0.45; and / or, 0.06 mm ≤ D mm ≤ 1.5 mm.

[0153] Specifically, by providing a protrusion 12 at the end of the shell body 11 near the opening, the local wall thickness of the shell 1 at the opening is increased, ensuring sufficient forming space for the first welding line 3, guaranteeing the welding strength between the shell 1 and the cover plate 2, and reducing the risk of cracking of the welding line between the shell 1 and the cover plate 2. Along the wall thickness direction of the shell 1, when the protrusion 12 protrudes too small (D mm) from the shell body 11, it cannot provide sufficient molten pool space for the first welding line 3, easily leading to insufficient penetration depth, and consequently, insufficient welding strength between the shell 1 and the cover plate 2. When D mm is too large, the excessively thick protrusion 12 will compress the internal space of the cell, causing the shell 1 and the cell 4 to be closer together, making it easier for welding heat to be conducted to the separator, exacerbating the risk of thermal damage to the separator, and increasing the risk of insulation failure.

[0154] For example, when the value of D mm satisfies 0.06 mm ≤ D mm ≤ 1.5 mm, the value of D mm can be 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.10 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.18 mm, 0.20 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.31 mm, 0.34 mm, 0.37 mm, 0.40 mm, 0.41 mm, 0.45 mm, 0.50 mm, 0.55 mm, 0.60 mm, 0.65 mm, or 0.7 mm. The values ​​can be 0mm, 0.75mm, 0.80mm, 0.85mm, 0.87mm, 0.90mm, 0.92mm, 0.95mm, 1.00mm, 1.05mm, 1.10mm, 1.15mm, 1.20mm, 1.21mm, 1.23mm, 1.25mm, 1.28mm, 1.29mm, 1.30mm, 1.35mm, 1.40mm, 1.42mm, 1.45mm, 1.48mm, or 1.50mm, or any range formed by any two of the above values.

[0155] As a further preferred option, the value of D mm satisfies 0.1 mm ≤ D mm ≤ 1.3 mm.

[0156] When the value of D mm satisfies the preferred range of 0.1 mm ≤ D mm ≤ 1.3 mm, it can provide sufficient molten pool space for the first weld line 3, better ensure the welding strength between the shell 1 and the cover plate 2, and at the same time reduce the welding heat conduction to the diaphragm, thus better reducing the risk of thermal damage to the diaphragm.

[0157] For example, when the value of D mm satisfies the preferred range of 0.1 mm ≤ D mm ≤ 1.3 mm, the value of A can be 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.3 mm, 0.32 mm, 0.35 mm, 0.38 mm, 0.4 mm, 0.41 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, or 0.65 mm. The value could be 0.7mm, 0.75mm, 0.8mm, 0.82mm, 0.85mm, 0.87mm, 0.9mm, 0.92mm, 0.95mm, 1.0mm, 1.02mm, 1.05mm, 1.08mm, 1.1mm, 1.12mm, 1.15mm, 1.18mm, 1.2mm, 1.21mm, 1.23mm, 1.25mm, 1.28mm, 1.29mm, or 1.3mm, or any range formed by any two of the above values.

[0158] Specifically, along the direction of the penetration depth of the first weld line 3, when the ratio A of the diameter of the pore 31 to the maximum penetration depth of the first weld line 3 is too large, the proportion of pore 31 is too high, and the strength of the first weld line 3 is difficult to guarantee; while when A is too small, although the strength of the weld line can be improved, the welding heat input increases significantly, which can easily cause the diaphragm to melt due to heat, resulting in a decrease in insulation performance or even complete failure, posing a significant safety hazard.

[0159] For example, when the value of A satisfies 0.05 ≤ A ≤ 0.45, the value of A can be 0.05 or 0.055 or 0.06 or 0.067 or 0.072 or 0.075 or 0.08 or 0.081 or 0.082 or 0.085 or 0.09 or 0.095 or 0.1 or 0.105 or 0.11 or 0.115 or 0.12 or 0.124 or 0.130 or 0.135 or 0.140 or 0.145 or 0.150 or 0.152 or 0.16 or 0.17 The values ​​could be 0.18, 0.19, 0.195, 0.205, 0.215, 0.225, 0.235, 0.245, 0.253, 0.260, 0.27, 0.274, 0.280, 0.287, 0.295, 0.305, 0.315, 0.325, 0.335, 0.34, 0.341, 0.342, 0.35, 0.352, 0.4, 0.449, or 0.45, etc., or any range formed by any two of the above values.

[0160] As a further preferred option, the value of A satisfies 0.08≤A≤0.35.

[0161] When the value of A satisfies the preferred range of 0.08≤A≤0.35, the strength of the first weld line 3 can be better guaranteed, and the diaphragm can be better guaranteed not to melt due to heat.

[0162] For example, when the value of A satisfies the preferred range of 0.08 ≤ A ≤ 0.35, the value of A can be 0.08, 0.081, 0.082, 0.085, 0.088, 0.091, 0.094, 0.097, 0.10, 0.103, 0.106, 0.109, 0.112, 0.115, 0.118, 0.121, 0.124, 0.127, 0.13, 0.133, 0.136, 0.139, 0.142, 0.145, 0.148, 0.152, 0.155, 0.161, 0.167, or 0.173. The values ​​could be 0.179, 0.185, 0.191, 0.195, 0.201, 0.207, 0.213, 0.219, 0.225, 0.231, 0.237, 0.243, 0.249, 0.253, 0.259, 0.265, 0.271, 0.274, 0.281, 0.287, 0.293, 0.299, 0.305, 0.311, 0.317, 0.323, 0.329, 0.335, 0.341, 0.342, 0.345, or 0.35, or any range formed by any two of the above values.

[0163] Furthermore, in this application, the penetration depth of the first bonding wire 3 ranges from 0.3 mm to 2 mm. For example, the penetration depth of the first bonding wire 3 can be 0.3 mm, 0.5 mm, 0.75 mm, 1 mm, 1.2 mm, 1.45 mm, 1.6 mm, 1.75 mm, 1.9 mm, or 2 mm, or it can be any range formed by any two of the above values.

[0164] Furthermore, in this application, the aperture of the pore 31 ranges from 0.1 mm to 0.9 mm. For example, the aperture value of the pore 31 can be 0.1 mm, 0.23 mm, 0.35 mm, 0.42 mm, 0.5 mm, 0.58 mm, 0.65 mm, 0.73 mm, 0.8 mm, or 0.9 mm, or it can be a range formed by any two of the above values.

[0165] In some embodiments, the material of the outer shell 10 includes aluminum, with an aluminum content ≥92% by mass and a silicon content ranging from 0.2% to 0.6% by mass. In this case, the following condition is met: 0.3≤D / A≤29.

[0166] It should be noted that the material of the outer casing 10 includes aluminum, such as aluminum alloy. The test method for the element content in aluminum alloy refers to GB / T7999-2015 (Direct Reading Photoelectric Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys).

[0167] For example, in this embodiment, the value of D / A can be 0.3 or 0.45 or 0.72 or 0.98 or 1.3 or 1.65 or 2.02 or 2.47 or 3.01 or 3.65 or 4.42 or 5.35 or 6.48 or 7.85 or 9.52 or 11.55 or 14.02 or 17.05 or 20.78 or 23.25 or 25.12 or 26.78 or 27.95 or 28.62 or 29, etc., or it can be a range formed by any two of the above values.

[0168] In some embodiments, the material of the outer shell 10 includes steel, wherein the total mass content of sulfur and phosphorus is in the range of 0.01% to 0.07%, and in this case, the following condition is met: 0.17≤D / A≤25.

[0169] It should be noted that the material of the outer casing 10 includes steel, such as stainless steel. The test method for the element content in stainless steel refers to GB / T11170-2008 (Determination of multi-element content in stainless steel by spark discharge atomic emission spectrometry (conventional method)).

[0170] Furthermore, the composition and content of the outer shell 10 material are as follows: Mainly includes: Carbon content: 0.001~0.03%; Chromium content: 16-19%; Phosphorus: 0.001~0.04%; Sulfur content: 0.001~0.03%; Iron content: 80.9%-83.997%; Also includes: Silicon element: 0.01~1%; Manganese content: 0.01~1.5%; Niobium: 0.01~0.4%; Titanium element: 0.01~0.4%; Nickel content: 3-10%.

[0171] For example, in this embodiment, the value of D / A can be 0.17 or 0.34 or 0.58 or 0.85 or 1.12 or 1.45 or 1.83 or 2.27 or 2.78 or 3.41 or 4.17 or 5.09 or 6.23 or 7.64 or 9.38 or 11.54 or 14.21 or 16.88 or 19.55 or 21.32 or 22.47 or 23.51 or 24.23 or 24.76 or 25, etc., or it can be any range formed by any two of the above values.

[0172] In some embodiments, the penetration direction of the first weld line 3 is perpendicular to the plane containing the large surface of the cover plate 2, wherein the large surface of the cover plate 2 refers to the surface with the largest area among all the outer surfaces of the cover plate 2; in this case, the following condition is met: 0.28≤D / A≤29.

[0173] At this time, the battery adopts a side welding method. The direction of the penetration of the first weld line 3 is not consistent with the direction of the force when the outer shell 10 bursts open. This can appropriately reduce the welding strength requirement in order to balance the difficulty of the process and the reliability of the structure.

[0174] As a variation, the penetration direction of the first weld line 3 can also be parallel to the plane where the large surface of the cover plate 2 is located. In this case, the welding strength between the shell 1 and the cover plate 2 is better after welding, but it is difficult to achieve in terms of process.

[0175] For example, in this embodiment, the value of D / A can be 0.28 or 0.56 or 0.84 or 1.15 or 1.47 or 1.82 or 2.21 or 2.63 or 3.1 or 3.62 or 4.21 or 4.88 or 5.65 or 6.54 or 7.58 or 8.81 or 10.28 or 12.07 or 14.27 or 17.05 or 20.58 or 23.21 or 25.37 or 27.45 or 29, etc., or it can be a range formed by any two of the above values.

[0176] In some embodiments, the minimum thickness of the cover plate 2 is greater than the maximum wall thickness of the housing 1 located at the protrusion 12.

[0177] By limiting the minimum thickness of the cover plate 2 to be greater than the maximum wall thickness of the shell 1 located at the protrusion 12, the deformation resistance of the cover plate 2 under high pressure impact is effectively improved, and the structural strength is not insufficient due to the cover plate 2 being too thin.

[0178] According to an embodiment of this application, another aspect provides a battery cell, comprising: As described above, the housing components; Battery cell 4 is placed inside the housing assembly.

[0179] In some embodiments, the battery cell includes a terminal assembly 6, which is disposed on the cover plate 2. The minimum distance between the terminal assembly 6 and the first bonding line 3 is K mm, satisfying 5 mm ≤ K mm ≤ 28 mm.

[0180] Since the electrode assembly 6 is electrically connected to the tab of the battery cell 4, during the charging and discharging process, the current is conducted to the electrode assembly 6 through the tab, causing a significant local temperature rise in the electrode assembly 6. At the same time, since the electrode assembly 6 is close to the opening area of ​​the cover plate 2, heat is easily conducted to the first bonding wire 3, which in turn aggravates the accumulation of thermal stress in the first bonding wire 3, resulting in a high risk of cracking of the first bonding wire 3.

[0181] In addition, the housing assembly also includes an insulating member 5, which is disposed between the cover plate 2 and the battery cell 4 along a first direction. Specifically, the insulating member 5 is disposed between the terminal post and the lower surface of the battery housing body, for insulating the terminal post (electrode terminal) from the lower surface (or bottom surface) of the cover plate, and for insulating the battery cell from the cover plate, thereby reducing the risk of short circuit.

[0182] The insulating component 5 can be plastic, rubber, or other insulating materials. The plastic can be polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), or polyvinyl chloride (PVC). The rubber can be nitrile rubber or isobutyl rubber.

[0183] Combination Figure 5 As shown, the insulating component 5 is disposed between the cover plate 2 and the battery cell 4 along the first direction to block the electrical path between the cover plate 2 and the battery cell 4. However, the insulating component 5 is located relatively close to the opening, making it susceptible to deformation due to welding heat, which can lead to melting or carbonization of the insulating component 5 and thus reduce its insulation performance. Especially when the thickness of the protrusion 12 is greater, the temperature gradient in the area where the insulating component 5 is located intensifies as the welding heat input further increases, making it more prone to thermal deformation of the insulating component 5.

[0184] This embodiment ensures sufficient thermal isolation between the electrode assembly 6 and the first bonding wire 3 by limiting the lower limit of the minimum distance K mm between them, thus avoiding the risk of cracking due to the accumulation of thermal stress in the first bonding wire 3. At the same time, it reduces the heat conduction from welding to the insulating component 5 in contact with the electrode assembly 6, thereby reducing the risk of thermal deformation of the insulating component 5. Furthermore, by limiting the upper limit of K mm, it prevents the electrode assembly 6 from moving too far away from the first bonding wire 3, which could result in insufficient current flow area for the electrode assembly 6.

[0185] For example, in this embodiment, the value of K mm can be 5 mm, 6.2 mm, 7.5 mm, 8.8 mm, 10.1 mm, 11.3 mm, 12.6 mm, 13.9 mm, 15.2 mm, 16.5 mm, 17.7 mm, 18.9 mm, 20.1 mm, 21.3 mm, 22.5 mm, 23.7 mm, 24.9 mm, 26.1 mm, 27.3 mm, 6.8 mm, 9.4 mm, 14.5 mm, 19.6 mm, 25.5 mm, or 28 mm, or it can be any range formed by any two of the above values.

[0186] According to an embodiment of this application, another aspect provides a battery pack 810, see [link to embodiment]. Figure 12 , Figure 12 An exploded view of the battery pack in some embodiments of this application is shown; the battery pack 810 includes: The housing 811; and a plurality of battery cells as described above, housed within the housing 811; The housing 811 includes a bottom wall, on which individual battery cells are fixedly mounted.

[0187] The battery pack 810 also includes a cover 812, which is positioned over the opening of the housing 811 and is sealed to the housing 811 to form a closed chamber for accommodating individual battery cells. A sealing element is provided between the cover 812 and the housing 811, extending along the edge of the opening of the housing 811 to fill the gap between the cover 812 and the housing 811. This prevents external moisture, dust, and other impurities from entering the closed chamber, thereby ensuring that the individual battery cells operate in a relatively clean and stable environment, and thus improving the overall safety and service life of the battery pack 810.

[0188] The battery pack 810 is configured on an electrical device, such as inside an electric vehicle, and can be installed at the bottom, front, or rear of the vehicle. The battery pack 810 provides electrical support to the electric vehicle, for example, acting as its operating power source. The electric vehicle may also be equipped with a controller and a motor; the controller is used to manage the supply of electrical energy from the battery pack to the motor to meet the power needs of the electric vehicle during starting, navigation, and driving.

[0189] The battery pack 810, as a rechargeable battery, is the power source for new energy vehicles. The battery pack includes a housing 811 and multiple battery cells housed within the housing 811. The housing 811 provides space for the battery cells and other components, while also providing dustproof, waterproof, and protective functions to the internal components, thereby reducing the adverse effects of external liquids or foreign objects on the effectiveness and performance of the battery cells and other components, effectively extending the battery pack's lifespan. The shape of the housing 811 is not limited; for example, it can be a cuboid, cylinder, etc.

[0190] The material of the 811 enclosure can also be flexibly selected, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0191] In this embodiment, the battery pack 810 includes multiple battery groups 813. Each sub-accommodation space of the housing 811 is provided with a battery group 813. Each battery group 813 includes multiple battery cells stacked together. The stacking direction of the battery cells can be a direction parallel to the plane of the bottom plate of the housing 811.

[0192] The battery pack 810 also includes a battery management system (BMS), a thermal management system, an electrical connection system (high-voltage / low-voltage connectors, wiring harnesses, etc.), structural components (casing, brackets, etc.), and protective components. These components are housed within a casing 811 and sealed by a cover 812, forming a complete functional unit capable of directly outputting electrical energy. The battery management system (BMS) is used to detect the operating status of the battery pack and its individual cells, and to manage the battery modules and their individual cells. The battery management system includes a battery management unit (BMU), a cell measurement circuit (CMC), sensors, and some electronic control devices. The battery management system includes at least one processor and a memory. The memory can be built into the battery management system or externally located outside the battery management system. The memory can also be remotely configured and connected to the battery management system via a network.

[0193] According to an embodiment of this application, in another aspect, a battery device is also provided, comprising: One or more battery packs 810 as described above.

[0194] The battery device 800 can serve as an operating power source for electrical devices, or as a driving power source for electrical devices, replacing or partially replacing fuel or natural gas to provide driving power for vehicles.

[0195] Electrical devices include energy storage equipment, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace and many other technological fields.

[0196] The following uses vehicle 900 as a specific example of an electrical device for illustration. See also Figure 11 , Figure 11The diagram illustrates the structure of a vehicle in some embodiments of this application. The vehicle 900 can be a new energy vehicle, encompassing various types such as pure electric vehicles, hybrid electric vehicles, and range-extended electric vehicles. The battery device 800 can be located at the bottom, front, or rear of the vehicle 900, providing electrical support to the vehicle 900, for example, acting as the vehicle 900's operating power source. Furthermore, the vehicle 900 typically also includes a controller 700, which manages the discharge process of the battery device 800 to cover various power needs during vehicle start-up, navigation, and driving.

[0197] In some embodiments, the battery device 800 comprises one or more battery packs 810, which can be connected in series, parallel, or a hybrid configuration. A hybrid configuration refers to the simultaneous presence of series and parallel connections in the connection of multiple battery packs 810. In other embodiments, the battery device 800 is a cluster-level battery architecture composed of multiple battery packs 810 connected in series, wherein the number of battery packs 810 in each cluster is strictly configured according to voltage and capacity requirements. More specifically, the battery unit of the battery device 800 includes multiple batteries, some of which are connected in series to form a cluster that meets a preset power supply voltage requirement, and at least one spare battery among the multiple batteries is bypassed.

[0198] Regarding the measurement of dimensions, thickness, distance, and area involved in this application, a micrometer, caliper, or scanning electron microscope can be used to measure dimensions, thickness, distance, etc., and the area can be calculated from the dimensions.

[0199] The method for preparing the battery cell in this application is as follows: (1) Preparation of the positive electrode: The positive electrode active material, conductive agent (e.g., acetylene black), and binder (e.g., PVDF) are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, the positive electrode sheet is obtained by rolling and slitting.

[0200] Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98):(4~1):(4~1).

[0201] (2) Preparation of negative electrode: The negative electrode active material, conductive agent (e.g., acetylene black), thickener (e.g., carboxymethyl cellulose (CMC)), and binder (e.g., styrene-butadiene rubber (SBR)) are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, the negative electrode sheet is obtained by rolling and slitting.

[0202] Specifically, the ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0203] (3) Preparation of electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0204] (4) Preparation of the diaphragm: Polyethylene film is selected as the diaphragm.

[0205] (5) Preparation of lithium-ion batteries: The aforementioned positive electrode sheet, separator, and negative electrode sheet are sequentially wound or stacked to form a bare cell. The bare cell is placed in a battery casing, which is a square casing, and the casing is welded to a cover plate to form the first weld line. The battery is dried, injected with electrolyte, and then packaged, allowed to stand, formed, and volume-adjusted to obtain a lithium-ion battery.

[0206] In addition to the above-mentioned battery material selection, this application may also select other materials, not limited to the materials limited by the above preparation method. The positive electrode active material may be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate. The conductive agent in the positive electrode sheet may also be selected from one or more of graphite, superconducting carbon, Ketjen black, conductive carbon black, carbon nanotubes, graphene, and carbon nanofibers. The binder in the positive electrode sheet may also be selected from polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene- The positive electrode current collector can be selected from one or more of the following: tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.; the positive electrode current collector can also be selected from one or more of the following: stainless steel with silver plating, aluminum, nickel, carbon electrode, carbon, nickel, titanium, etc.; the positive electrode current collector can also include composite current collectors, which can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of poly(ethylene terephthalate), polyethylene terephthalate, polyethylene, etc.).

[0207] The negative electrode active material can be selected from one or more of the following negative electrode active main materials: artificial graphite, natural graphite, silicon carbide, silicon oxide, lithium titanate, etc.; the conductive agent in the negative electrode sheet can be selected from one or more of the following: conductive carbon black, conductive graphite, carbon nanotubes, graphene, carbon fiber, etc.; the binder in the negative electrode sheet can be selected from one or more of the following: styrene-butadiene rubber, polyacrylic acid and its salts, sodium alginate, etc.; the thickener in the negative electrode sheet can be selected from one or more of the following: sodium carboxymethyl cellulose, polyacrylonitrile multi-component copolymer, etc.; the negative electrode current collector can also be selected from one or more of the following: stainless steel with silver plating, stainless steel, copper, nickel, carbon electrode, carbon, nickel, titanium, etc.; the negative electrode current collector can also include composite current collectors, which can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0208] The membrane material can be selected from at least one of glass fiber, nonwoven fabric, polypropylene (PP) and polyvinylidene fluoride.

[0209] The following, in conjunction with Table 1, describes the separation shrinkage test and the first weld line cracking test of the battery provided in this application through several embodiments and comparative tests to verify its qualification.

[0210] Among them, performance 1, diaphragm shrinkage test, is conducted as follows: Following the battery preparation method described above, 50 batteries were prepared for each embodiment and comparative example. The length of the separator before the cell was inserted into the casing in each battery was measured and recorded using vernier calipers, denoted as L1 mm. The A and D values ​​of the batteries are shown in Table 1 below. All other structures are identical. Each battery was discharged at a rate of 0.33C to the lower limit voltage at 25°C, allowed to stand for 10 minutes, and then charged at a rate of 0.33C to the upper limit voltage. The batteries were then charged at a constant voltage until the cutoff current equals 0.05C, allowed to stand for 10 minutes, and this cycle was repeated 3 times. After 3 cycles, the batteries were discharged at 0.33C to the lower limit voltage; the capacity at this point is the actual capacity of the battery, denoted as C1. At 25°C, the batteries were charged at a rate of 1C1 (1 times the actual capacity) to the upper limit voltage, and then charged at a constant voltage until the cutoff current equals 0.05C, allowed to stand for 20 minutes. Then, discharge at a rate of 1C1 (1 times the actual capacity) until the lower limit voltage is reached. After standing for 20 minutes, charge at 1C1 (1 times the actual capacity) and discharge at 1C1 (1 times the actual capacity) for 300 cycles. Then, disassemble the battery, remove the cells, and measure the length of the cell separator with calipers, recording it as L2mm. Calculate the separator shrinkage rate according to the formula: separator shrinkage rate = ((L1-L2) / L1)×100%. If the separator shrinkage rate > 5%, the battery is unqualified, and the number is recorded as n. If the separator shrinkage rate ≤ 5%, the battery is qualified. Calculate the percentage of unqualified batteries according to the formula (n / 50)×100%. If the percentage of unqualified batteries ≤ 2%, the test result is good. If the percentage of unqualified batteries > 2% and ≤ 6%, the test result is qualified. If the percentage of unqualified batteries > 6%, the test result is unqualified.

[0211] When the positive electrode active material includes nickel-cobalt-manganese ternary materials, the upper limit voltage of the battery is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material includes lithium iron phosphate, the upper limit voltage of the battery is 3.65V and the lower limit voltage is 2.5V.

[0212] The positive electrode active material used in this test was selected from LiNi. 0.6 Co 0.2 Mn 0.2 Taking O2 as an example, all other positive electrode materials meet the above test requirements, and the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; the negative electrode active material is selected from artificial graphite, and all other negative electrode materials meet the above test requirements, and the ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2; the battery cell is a wound battery cell, and all other battery cell forms meet the above test requirements.

[0213] Among them, performance 2, the first weld line cracking test, is conducted as follows: Following the battery fabrication method described above, 50 batteries were prepared for each embodiment and comparative example. The A and D values ​​of the batteries are shown in Table 1 below. All other structures are identical. Each battery was discharged at 0.33C to the lower limit voltage at a temperature of 25°C, allowed to stand for 10 minutes, and then charged at 0.33C to the upper limit voltage. It was then charged at a constant voltage until the cutoff current equals 0.05C, allowed to stand for 10 minutes, and this cycle was repeated 3 times. After 3 cycles, the battery was discharged at 0.33C to the lower limit voltage. The capacity at this point is the actual capacity of the battery, denoted as C1. At 25°C, the battery was charged at a rate of 3C1 (3 times the actual capacity) to the upper limit voltage. The battery was charged at a constant voltage until the cutoff current was equal to 0.05C. After standing for 20 minutes, it was discharged at a discharge rate of 3C1 (3 times the actual capacity) until the lower limit voltage was reached. After standing for 20 minutes, it was charged at 3C1 (1 times the actual capacity). After 1000 cycles of the 3C1 (1 times the actual capacity) discharge cycle, the first bonding wire was observed to see if it was cracked. If it was cracked, the number of batteries was recorded as n. The battery cracking rate was calculated according to the formula (n / 50) × 100%. If the battery cracking rate was ≤2%, the test result was good. If the battery cracking rate was >2% and ≤4%, the test result was qualified. If the battery cracking rate was >4%, the test result was unqualified.

[0214] When the positive electrode active material includes nickel-cobalt-manganese ternary materials, the upper limit voltage of the battery is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material includes lithium iron phosphate, the upper limit voltage of the battery is 3.65V and the lower limit voltage is 2.5V.

[0215] The positive electrode active material used in this test was selected from LiNi. 0.6 Co 0.2 Mn 0.2 Taking O2 as an example, all other positive electrode materials meet the above test requirements, and the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; the negative electrode active material is selected from artificial graphite, and all other negative electrode materials meet the above test requirements, and the ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2; the battery cell is a wound battery cell, and all other battery cell forms meet the above test requirements.

[0216] Table 1

[0217] Regarding the test results, referring to Table 1 above, the explanation is as follows: As can be seen from Examples 1-17, when the formula value of D / A meets the range of 0.17≤D / A≤29, the diaphragm shrinkage test results are all good or qualified, and no unqualified results are found; the first weld line cracking test results are all good or qualified, and no unqualified results are found; the performance requirements are met.

[0218] In Comparative Examples 2 and 4, the D / A value was below the lower limit, and the first weld crack test showed that the result was unqualified and could not meet the performance requirements.

[0219] In Comparative Examples 1 and 3, the value of D / A exceeded the upper limit, and the diaphragm shrinkage test result was unqualified, failing to meet the performance requirements.

[0220] In Examples 9 to 17, the diaphragm shrinkage test and the first weld line cracking test all yielded good results, meeting the performance requirements.

[0221] In Examples 1, 2, and 5, although D / A satisfies the range of 0.17≤D / A≤29, the value of D / A is relatively large. This results in the proportion of unqualified batteries being >2% and ≤6% when the separator shrinkage test is performed. The test result is only qualified, but still meets the performance requirements.

[0222] In Examples 3, 4, 6, and 8, although D / A satisfies the range of 0.17≤D / A≤29, the value of D / A is relatively small, which causes the battery to only pass the first weld line cracking test, but still meet the performance requirements.

[0223] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by this application.

Claims

1. A housing assembly, characterized in that, include: The outer shell (10) has a receiving cavity (14) formed inside it; the outer shell (10) includes a housing (1) with an opening at least one end along a first direction, and a cover plate (2) covering the opening, the cover plate (2) being welded to the housing (1) to form a first weld line (3). The housing (1) includes a housing body (11) and a protrusion (12). The protrusion (12) is disposed on the side of the housing body (11) facing the receiving cavity (14), and the protrusion (12) is disposed at the end of the housing (1) near the opening. The protrusion (12) protrudes from the housing body (11). Along the wall thickness direction of the housing (1), the protrusion (12) protrudes from the housing body (11) by a dimension of D mm. The first weld line (3) has pores (31) inside. Along the melting depth direction of the first weld line (3), the ratio of the pore diameter (31) to the maximum melting depth of the first weld line (3) is A. It satisfies: 0.17≤D / A≤29.

2. The housing assembly according to claim 1, characterized in that, The first weld wire (3) includes a first end (301) and a second end (302) along the weld depth direction. The first end (301) is disposed away from the receiving cavity (14) compared to the second end (302). The pore (31) is disposed at intervals from at least one of the first end (301) and the second end (302).

3. The housing assembly according to claim 2, characterized in that, Along the melting depth direction, the minimum distance between the pore (31) and the first end (301) is E mm, which satisfies E mm ≥ 0.1 mm. And / or, along the melting depth direction, the minimum distance between the pore (31) and the second end (302) is E mm, satisfying E mm ≥ 0.1 mm.

4. The housing assembly according to claim 2, characterized in that, Define the center line of the first end (301) and the second end (302) along the melting depth direction as S. The center line S passes through the midpoint of the line connecting the first end (301) and the second end (302) along the melting depth direction, and the extension direction of the center line S is perpendicular to the melting depth direction; the pore (31) is arranged to coincide with the center line S.

5. The housing assembly according to claim 2, characterized in that, Define the center line of the first end (301) and the second end (302) along the melting depth direction as S. The center line S passes through the midpoint of the line connecting the first end (301) and the second end (302) along the melting depth direction, and the extension direction of the center line S is perpendicular to the melting depth direction. The pores (31) are spaced apart from the center line S. The minimum distance between the pores (31) and the center line S along the melting depth direction is F mm, which satisfies 0.05 mm ≤ F mm ≤ 0.95 mm.

6. The housing assembly according to claim 1, characterized in that, In one of the cross sections perpendicular to the extension direction of the first weld line (3), the cross-sectional shape of the pore (31) is circular or elliptical.

7. The housing assembly according to claim 1, characterized in that, The ratio of the maximum diameter of a single pore (31) to the minimum diameter of a single pore (31) ranges from 1 to 3.

8. The housing assembly according to claim 1, characterized in that, The pore diameter of the air hole (31) is A1 mm, which satisfies 0.1 mm ≤ A1 mm ≤ 0.9 mm.

9. The housing assembly according to claim 1, characterized in that, In one of the cross sections perpendicular to the extension direction of the first weld line (3), there are multiple pores (31), the minimum spacing between adjacent pores (31) is G mm, which satisfies 0.05 mm ≤ G mm ≤ 1.5 mm; and the diameter of a single pore (31) is A2 mm, which satisfies 0.1 mm ≤ A2 mm ≤ 0.7 mm.

10. The housing assembly according to claim 1, characterized in that, In one of the cross sections perpendicular to the extension direction of the first weld line (3), the total area of ​​the pores (31) is S1 mm², and the total area of ​​the first weld line (3) in this cross section is S2 mm², satisfying 0.1% ≤ S1 / S2 ≤ 6%.

11. The housing assembly according to any one of claims 1 to 10, characterized in that, Along the first direction, the cover plate (2) includes a first end face (201) near the receiving cavity (14), and the housing (1) includes a bottom surface (109) opposite to the cover plate (2). The minimum distance between the protrusion (12) and the bottom surface (109) of the shell is H1mm, and the minimum distance between the first end face (201) and the bottom surface (109) of the shell is H2mm, satisfying H1mm < H2mm.

12. The housing assembly according to claim 11, characterized in that, The cover plate (2) includes a body portion (21) and an extension portion (22) extending from the body portion (21) toward the receiving cavity (14) in the first direction. The extension portion (22) is adapted to be inserted into the housing (1), and the projection of the extension portion (22) onto the plane of the body portion (21) in the first direction does not coincide with the projection of the protrusion (12) onto the plane of the body portion (21).

13. The housing assembly according to any one of claims 1 to 10, characterized in that, At least a portion of the protrusion (12) forms the first bonding line (3).

14. The housing assembly according to claim 13, characterized in that, Along the first direction, the end of the protrusion (12) away from the opening is spaced apart from the first welding line (3) and the spacing distance is H mm, satisfying 0.2 mm ≤ H mm ≤ 14.7 mm.

15. The housing assembly according to any one of claims 1 to 10, characterized in that, Along the first direction, the ratio of the size of the protrusion (12) to the size of the shell body (11) is 0.35 to 3.

2.

16. The housing assembly according to any one of claims 1 to 10, characterized in that, The housing (1) includes a bottom surface (109) disposed opposite to the cover plate (2); along the first direction, the protrusion (12) includes a first protruding end (121) and a second protruding end (122), the second protruding end (122) being disposed closer to the bottom surface (109) of the housing than the first protruding end (121); Along the wall thickness direction of the shell (1), the first protruding end (121) protrudes from the shell body (11) by a dimension of J1mm, and the second protruding end (122) protrudes from the shell body (11) by a dimension of J2mm, satisfying J2mm < J1mm.

17. The housing assembly according to claim 16, characterized in that, The size of the first protrusion (121) to the second protrusion (122) protruding from the shell body (11) gradually decreases.

18. The housing assembly according to claim 16, characterized in that, The protrusion (12) includes a straight section (123) and a transition section (124). The first protrusion end (121) is located on the side of the straight section (123) near the cover plate (2), and the second protrusion end (122) is located on the side of the transition section (124) near the bottom surface (109) of the shell.

19. The housing assembly according to any one of claims 1 to 10, characterized in that, The housing (1) further includes a second protrusion (13). Along the wall thickness direction of the housing (1), the second protrusion (13) is disposed on the side of the housing body (11) away from the protrusion (12), and the second protrusion (13) and the protrusion (12) are disposed opposite to each other along the wall thickness direction of the housing (1).

20. The housing assembly according to any one of claims 1 to 10, characterized in that, The protrusion (12) extends for a length of L1 mm around the opening of the housing (1), and the circumference of the opening of the housing (1) is L2 mm, satisfying 0.1 ≤ L1 / L2 ≤ 1.

21. The housing assembly according to any one of claims 1 to 10, characterized in that, The housing (1) includes two opposing first sidewalls (101) and two opposing second sidewalls (102), the first sidewalls (101) and the second sidewalls (102) enclosing a rectangular opening; the area of ​​the first sidewall (101) is larger than the area of ​​the second sidewall (102), the first sidewall (101) and the second sidewall (102) are connected by a transition wall (103), and the protrusion (12) is at least partially located on the transition wall (103).

22. The housing assembly according to any one of claims 1 to 10, characterized in that, satisfy: 0.05 ≤ A ≤ 0.45; and / or, 0.06 mm ≤ D mm ≤ 1.5 mm.

23. The housing assembly according to any one of claims 1 to 10, characterized in that, The outer shell (10) is made of aluminum, with an aluminum content of ≥92% by mass and a silicon content of 0.2% to 0.6% by mass. In this case, the following condition is met: 0.3≤D / A≤29.

24. The housing assembly according to any one of claims 1 to 10, characterized in that, The outer shell (10) is made of steel, wherein the total mass content of sulfur and phosphorus is in the range of 0.01% to 0.07%, and at this time, the following condition is met: 0.17≤D / A≤25.

25. The housing assembly according to any one of claims 1 to 10, characterized in that, The penetration direction of the first weld line (3) is perpendicular to the plane of the large surface of the cover plate (2), wherein the large surface of the cover plate (2) refers to the surface with the largest area among all the outer surfaces of the cover plate (2); at this time, the following condition is met: 0.28≤D / A≤29.

26. The housing assembly according to any one of claims 1 to 10, characterized in that, The minimum thickness of the cover plate (2) is greater than the maximum wall thickness of the housing (1) located at the protrusion (12).

27. A single battery cell, characterized in that, include: The housing assembly as described in any one of claims 1 to 26 above; The battery cell (4) is placed inside the housing assembly.

28. The battery cell according to claim 27, characterized in that, The battery cell includes a terminal assembly (6), which is disposed on the cover plate (2). The minimum distance between the terminal assembly (6) and the first welding line (3) is K mm, which satisfies 5 mm ≤ K mm ≤ 28 mm.

29. A battery pack, characterized in that, include: A housing (811); and a plurality of battery cells as described in any one of claims 27 to 28, disposed within the housing (811); The housing (811) includes a bottom wall, and the battery cell is fixedly mounted on the bottom wall.

30. A battery device, characterized in that, include: One or more battery packs as described in claim 29 above.

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