A battery and an electric device

Abstract

The application discloses a battery and an electric device, relates to the technical field of batteries, and comprises a shell and a battery cell arranged in the shell. The shell comprises a first end face part. The first end face part and a current output part of the battery cell are electrically connected through a current collector. A welding area of the first end face part is welded to the current collector and forms a first welding mark. The projection area of the first welding mark on a target plane is S1 mm 2 . The projection area of the current collector on the target plane is S2 mm 2 . S1 / S2=k. The wall thickness of the first end face part at the welding area is b mm. The shell comprises an aluminum shell containing magnesium elements, and the mass content of the magnesium elements is a%. The range of a / (b*k) is 0.12-1047.83. The application can avoid the problem that too many pores are generated at the welding position between the first end face part and the current collector, thus causing cracking at the welding position, ensures the sealing property of the welding position, and ensures the strength of the welding position.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a battery and an electrical device. Background Technology

[0002] In current battery designs, the terminals serving as the current output section protrude from the battery casing, resulting in significant external space occupation, reduced overall space utilization, and impacted battery pack efficiency. To improve space utilization, a common practice is to use the casing as the external current output section for one of the terminals. However, in practical applications, this approach has been found to be problematic because the current output section of the battery cell is connected to the casing via a current collector. The welded joint between the current collector and the casing is prone to abnormal cracking, potentially leading to seal failure at the weld and posing a safety hazard.

[0003] Therefore, how to avoid abnormal cracking at the weld and improve safety in use is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a battery that avoids abnormal cracking at the weld joint and improves safety in use; Another object of this application is to provide an electrical device having the above-mentioned battery.

[0005] To achieve the above objectives, this application provides the following technical solution: A first aspect of this application provides a battery, including a housing and a battery cell disposed within the housing, the housing including a first end face; The first end face is electrically connected to the current output section of the battery cell via a current collector. The welding area of ​​the first end face is welded to the current collector, forming a first solder mark. The projected area of ​​the first solder mark on the target plane is S1mm. 2 The projected area of ​​the current collector on the target plane is S2mm. 2 S1 / S2=k, the wall thickness of the first end face at the welding area is bmm, the outer shell includes an aluminum shell containing magnesium, and the mass content of magnesium is a%, a / (b×k) ranges from 0.12 to 1047.83, and the target plane is a plane parallel to the first end face (120).

[0006] The battery disclosed in the above technical solution selects a / (b×k) within the range of 0.12 to 1047.83. This avoids the problem of excessively large values ​​of the above relationship, which would result in too many pores at the weld between the first end face and the current collector. This would cause the pores at the weld between the first end face and the current collector to continuously enlarge due to high temperatures during battery cycling, leading to poor sealing and even the risk of leakage, gas leakage, and uncontrolled thermal runaway. It also avoids the problem of insufficient weld strength and cracking due to excessively small values ​​of the above relationship.

[0007] This embodiment ensures the structural strength of the shell by comprehensively controlling the magnesium content (a%), the wall thickness (bmm) of the first end face at the welding area, and the area ratio (k) of the first weld mark to the current collector. This avoids excessive porosity at the weld between the first end face and the current collector, which could lead to cracking at the weld, and ensures the sealing of the weld while also guaranteeing its strength.

[0008] A second aspect of this application provides an electrical device comprising a battery as described in any of the preceding claims.

[0009] The electrical device disclosed in the above technical solution has all the technical effects of the battery mentioned above, and will not be described in detail here. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the battery structure disclosed in an embodiment of this application; Figure 2 This is a cross-sectional view of the battery disclosed in an embodiment of this application; Figure 3 This is a partial cross-sectional view of the battery disclosed in an embodiment of this application; Figure 4 This is an exploded view of the battery disclosed in an embodiment of this application; Figure 5 This is a schematic diagram of the current collector structure disclosed in the embodiments of this application; Figure 6 This is a top view of the current collector disclosed in the embodiments of this application; Figure 7 for Figure 6 Sectional view along AA; Figure 8 This is a top view of a current collector disclosed in another embodiment of this application; Figure 9 This is a schematic diagram of the structure of the first end face and pole disclosed in the embodiments of this application; Figure 10 This is a cross-sectional view of the first end face and pole disclosed in an embodiment of this application; Figure 11 This is a top view of the first end face disclosed in the embodiments of this application.

[0012] The meanings of the various reference numerals in the figure are as follows: 100 - Outer shell; 110 - Outer shell body; 120 - First end face; 121 - Groove; 130 - Second end face; 200 - Battery cell; 210 - Battery cell body; 220 - Electrode portion; 221 - First electrode; 222 - Second electrode; 230 - Side of casing; 300-Adapter; 400 - Current collector; 410 - First welding position; 420 - Second welding position; 510 - First solder mark; 511 - First end point; 512 - Second end point; 520 - Second solder mark; 530 - Third solder mark; 600-Pole Column. Detailed Implementation

[0013] This application discloses a battery to prevent abnormal cracking at the weld joint and improve safety during use; This application also discloses an electrical device having the above-described battery.

[0014] 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, and 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.

[0015] like Figures 1-4 As shown, the battery can store chemical energy and controllably convert it into electrical energy. In a recyclable battery, the active materials can be reactivated by charging after discharge, allowing it to continue to be used. The battery includes a casing 100 and battery cells 200 disposed within the casing 100.

[0016] Cell 200 is the component in the battery where electrochemical reactions occur; it is the smallest unit in the battery capable of carrying out electrochemical reactions such as charging / discharging.

[0017] Cell 200 is the basic unit in a battery, typically including a positive electrode, a negative electrode, and a separator. Cell 200 can be either wound or stacked. The main body of cell 200 includes a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrode.

[0018] 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, a conductive agent, and a binder. 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 manganese oxides, and their modified compounds.

[0019] 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 alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0020] 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, Super P, etc.), carbon nanotubes, graphene and carbon nanofibers.

[0021] 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.

[0022] The negative electrode sheet 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.). The negative electrode active layer includes a negative electrode active material, conductive components, adhesives, etc.

[0023] 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.

[0024] During battery charging, active ions (such as Li) from the positive electrode are embedded in the negative electrode, while electrons from the positive electrode are transferred to the negative electrode through the external circuit to maintain charge balance. During discharge, active ions (such as Li) previously embedded in the negative electrode can be released, while electrons from the negative electrode are transferred to the negative electrode through the external circuit to maintain charge balance, thus achieving energy storage and release.

[0025] The current output section of the battery cell 200 includes a tab section 220, which comprises multiple single tabs. The tabs are disposed on one side of the positive / negative current collector battery cell 200 and are separately / integrated with the current collector. They are electrically connected to the current collector to conduct current through the corresponding current collector. When the tabs and current collector are separately disposed, they can be connected by welding. The tabs are made of a metal material with good electrical conductivity (such as copper, aluminum, or nickel).

[0026] The housing 100 is a component used to provide a receiving space to house the battery cell 200 and other components and isolate them from the outside environment. The housing 100 generally includes a housing body 110 with an opening at at least one end and a receiving cavity. The opening of the housing body 110 can be closed by a battery cover to seal and isolate the internal environment of the battery from the external environment. When the opening is sealed by a first end face 120, the first end face 120 serves as the battery cover; when the opening is sealed by a second end face, the second end face serves as the battery cover.

[0027] The outer shell 100 is made of aluminum, with an aluminum content ranging from 99% to 99.9%, and also includes at least one of the following elements: manganese, copper, iron, silicon, zinc, magnesium, chromium, and titanium.

[0028] The battery's current output section includes a terminal assembly. One end of the terminal assembly is electrically connected to the current output section (tab) of the cell 200, and the other end is electrically connected to an external device (the current output section of an adjacent battery or other electrical equipment) outside the casing 100. The battery can discharge to the external device through the current output section (tab) of the cell 200 and the current output section (terminal assembly) of the battery. An external power source can charge the battery through the current output section (tab) of the cell 200 and the current output section (terminal assembly) of the battery. The current output section (terminal assembly) of the battery can be directly connected to the current output section (tab) of the cell 200, or it can be electrically connected to the current output section (tab) of the cell 200 through a current collector assembly. The terminal assembly includes at least one of the following metal materials: copper, aluminum, aluminum alloy, and copper-aluminum alloy.

[0029] To improve welding reliability, batteries typically employ current collectors to connect the current output section of the cell 200 to the current output section on the casing. Located at the connection point between the current output section on the battery casing 100 (e.g., casing 100 / terminal 600) and the tab (i.e., the current output section of the cell 200), the current collector acts as a bridge for current transmission, ensuring uniform current distribution. Specifically, one end of the current collector is electrically connected to the current output section (tab) of the cell 200, and the other end is connected to the current output section of the battery (terminal assembly / casing), enabling current conduction between the tab and the terminal assembly / casing. The current collector is made of at least one of the following metals: copper, aluminum, aluminum alloy, or copper-aluminum alloy.

[0030] The shape and layout of the current collector assembly depend on the type, size, and application of the battery. Generally, the surface of the current collector assembly is flat, providing sufficient connection area for the tab assembly. Its surface is also designed with specific connection areas according to the distribution and connection requirements of the tab assembly and the terminals 600 / casing 100 (the terminals 600 and casing 100 serve as the current output parts of the battery). These areas may be equipped with solder points, riveting positions, or specialized snap-fit ​​structures to ensure a secure connection with the tabs, terminals, and casing.

[0031] As a crucial hub for current conduction within the battery, the current collector assembly collects the current from the tabs and transmits it to the terminals 600 / casing 100. During battery charging and discharging, the current generated by the electrode reactions is gathered by the tab assembly and then conducted to the current collector assembly, which in turn conducts it to the terminals 600 / casing 100, thus connecting it to the external circuitry. This process ensures stable and efficient current transmission between the battery's internal and external environments.

[0032] To improve space utilization, the outer casing 100 is often used directly as the external current output terminal of the battery, which can effectively improve space utilization. For example, the current output terminal of the cell 200 is welded to the outer casing 100 through the current collector 400 of the current collector assembly. However, in actual use, there is a risk of abnormal cracking at the welded joint between the outer casing 100 and the current collector 400, which may lead to the battery failing to seal at the weld, posing a safety hazard.

[0033] Research has revealed that the main reason for the cracking at the weld between the outer casing 100 and the current collector 400 is that during the welding process, at high temperatures, pores are easily generated in the molten pool, and the surface of these pores is often covered by a metal layer. If the metal layer completely covers the pores, they are easily missed during airtightness testing or weld interface defect detection, and are often mistakenly judged as qualified products.

[0034] After the battery is put into use, during the charge and discharge cycle, the casing 100 will generate heat due to the current passing through it. This causes heat to accumulate in the pore area and the pores to expand. Eventually, the metal layer covering the pores will crack, causing the welded joint to fail to seal, which in turn leads to liquid leakage, gas leakage, and even thermal runaway.

[0035] In addition, to improve the strength and weldability of the outer casing 100, trace elements such as magnesium are often added during the molding of the outer casing 100. However, the introduction of magnesium significantly increases the number of pores at the weld, thereby accelerating the expansion of pores and cracking of weld lines during battery cycling, further affecting the safety performance of the battery.

[0036] Based on this, this application discloses a battery to reduce the number of pores at the weld joint, avoid abnormal cracking at the weld joint, and improve safety in use. The applicant has discovered that by adjusting the mass content of magnesium in the casing, the wall thickness of the casing at the weld area, and the area ratio of the solder mark to the current collector, the structural strength of the casing, the number of pores at the weld joint, and the strength of the weld joint can be controlled.

[0037] like Figures 1-4 As shown, the battery disclosed in this application embodiment includes a casing 100 and a battery cell 200 disposed within the casing 100. The casing 100 is an external protective structure for the battery cell 200, used to house the battery cell 200 and isolate the battery cell 200 from the external environment. The casing 100 includes a first end face 120, which can be a battery cover plate welded to the opening of the casing body 110, or it can be an integrally formed structure with the casing body 110.

[0038] For ease of understanding, the portion of the current collector assembly connected to the housing 100 is defined as the current collector 400. In this embodiment, the first end portion 120 of the housing 100 is electrically connected to the current output portion (one polarity tab) of the battery cell 200 via the current collector 400. Specifically, the soldering area of ​​the first end portion 120 is soldered to the current collector 400, forming a first solder mark 510. Figures 5-7 As shown, the first welding position 410 of the current collector 400 is welded to the welding area of ​​the first end face 120 to form a first weld mark 510. The first welding position 410 of the current collector 400 can be on the outer edge side of the current collector 400 to ensure that the first welding position 410 has a large area.

[0039] The battery may also include an insulating element, which is at least partially located between the cell 200 and the current collector assembly, and the orthographic projection of the insulating element on the first end face 120 at least partially covers the orthographic projection of the first solder mark 510 on the first end face 120. The insulating element can be fixedly connected to the current collector assembly. The insulating element is made of at least one of polypropylene, polycarbonate, polyethylene terephthalate, and polyimide.

[0040] The projected area of ​​the first solder mark 510 on the target plane is S1mm. 2 The projected area of ​​the current collector 400 on the target plane is S2mm. 2 S1 / S2 = k. It should be noted that the target plane is a plane parallel to the first end face 120°. When the battery is cylindrical, the target plane is a plane perpendicular to the axis of the cylindrical battery.

[0041] The wall thickness of the first end face 120 at the welding area is b mm. The outer shell 100 includes an aluminum shell containing magnesium, and the mass content of magnesium is a%. Then, the range of a / (b×k) is 0.12~1047.83. For example, a / (b×k) can be 0.12, 1.00, 10.00, 50.00, 100.00, 150.00, 200.00, 300.00, 350.00, 400.00, 500.00, 550.00, 650.00, 700.00, 800.00, 900.00, 1000.00, 1047.83, etc. This embodiment does not limit the specific value of a / (b×k), and those skilled in the art can select it within the range of 0.12~1047.83 according to their needs.

[0042] The battery disclosed in this application selects a / (b×k) within the range of 0.12 to 1047.83. This avoids the situation where an excessively large value of the above relationship would result in too many pores at the weld between the first end face 120 and the current collector 400, causing the pores to continuously enlarge due to high temperatures during battery cycling, leading to poor sealing and even the risk of leakage, gas leakage, and uncontrolled thermal runaway. It also avoids the situation where an excessively small value of the above relationship would result in insufficient strength at the weld between the first end face 120 and the current collector 400, leading to cracking due to insufficient weld strength.

[0043] This embodiment comprehensively controls the magnesium content (a%), the wall thickness (bmm) of the first end face 120 at the welding area, and the area ratio (k) of the first weld mark 510 to the current collector 400, so that a / (b×k) is within the range of 0.12 to 1047.83. This avoids a value of a / (b×k) being too small, which would result in a low magnesium content (a%), leading to less aluminum lattice distortion and easier dislocation movement during welding, thus reducing the strength of the aluminum alloy weld. The embodiment also ensures that the wall thickness (bmm) of the first end face 120 at the welding area is controlled. If the value of k is too large, the heat will not be able to completely penetrate the first end face 120 when welding with the same power, resulting in less melting of the current collector 400 and poor strength of the first weld mark 510 formed between the current collector 400 and the first end face 120. If the value of k is too large, the projected area of ​​the first weld mark 510 will be larger than the projected area of ​​the current collector 400, which will easily cause the first end face 120 and / or the current collector 400 to overheat and soften during welding. At the same time, it will increase the stress between the first end face 120 and the current collector 400, resulting in a decrease in the strength of the first weld mark 510.

[0044] This embodiment comprehensively controls the magnesium content (a%), the wall thickness (bmm) of the first end face 120 at the welding area, and the area ratio (k) of the first weld mark 510 to the current collector 400. This ensures that a / (b×k) is within the range of 0.12 to 1047.83. It also avoids situations where a / (b×k) is too large, resulting in an excessively high magnesium content (a%), which would increase the solubility of hydrogen in liquid aluminum, leading to rapid hydrogen precipitation during solidification of the molten pool and the formation of numerous pores, thus reducing the sealing performance of the first weld mark. Conversely, if the wall thickness (bmm) of the first end face 120 at the welding area is too small, the proportion of pores in the thickness of the first end face 120 would be larger, reducing the airtightness of the first weld mark 510. Finally, if k is too small, the proportion of pores in the first weld mark 510 would increase, leading to a decrease in the sealing performance of the first weld mark 510.

[0045] In summary, this application comprehensively controls the magnesium content (a%), the wall thickness (bmm) of the first end face 120 at the welding area, and the area ratio (k) of the first weld mark 510 to the current collector 400, so that a / (b×k) is within the range of 0.12 to 1047.83. This ensures the structural strength of the outer shell 100, avoids excessive porosity at the weld between the first end face 120 and the current collector 400, which could lead to cracking at the weld, and ensures the sealing and strength of the weld.

[0046] Furthermore, the range of a / (b×k) can be from 0.41 to 180.00. For example, a / (b×k) can be 0.41, 1.00, 5.00, 10.00, 20.00, 40.00, 60.00, 80.00, 100.00, 120.00, 140.00, 160.00, 180.00, etc. This embodiment does not limit the specific value of a / (b×k), and those skilled in the art can select it within the range of 0.12 to 180.00 according to their needs.

[0047] In a specific embodiment of this application, the projected area S1mm of the first solder mark 510 on the target plane. 2 It can be 10mm 2 ~1200mm 2 For example, S1mm 2 It can be 10mm 2 100mm 2 200mm 2 300mm 2 400mm 2 500mm 2 600mm 2 700mm 2 800mm 2 900mm 2 1000mm 2 1100mm 2 1200mm 2 Etc. This embodiment addresses S1mm. 2 The specific value is not limited; those skilled in the art can adjust it according to requirements within 10mm. 2 ~1200mm 2 Choose from the range.

[0048] The projected area of ​​the current collector 400 on the target plane is S2mm. 2 It can be 125mm 2 ~3000mm 2 For example, S2mm 2 It can be 125mm 2200mm 2 400mm 2 600mm 2 800mm 2 1000mm 2 1200mm 2 1400mm 2 1600mm 2 1800mm 2 2000mm 2 2200mm 2 2400mm 2 2600mm 2 2800mm 2 3000mm 2 Etc. This embodiment addresses S2mm. 2 The specific value is not limited; those skilled in the art can adjust it according to requirements within 125mm. 2 ~3000mm 2 Choose from the range.

[0049] In a specific embodiment of this application, a% ranges from 0.1% to 5%. For example, a% can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. This embodiment does not limit the specific value of a%, and those skilled in the art can select from the range of 0.1% to 5% according to their needs.

[0050] This design avoids the problem of excessive pores at the weld between the first end face 120 and the current collector 400 due to excessive magnesium content, which could lead to poor sealing due to enlarged pores during battery cycling. It also avoids the problem of low weld strength and easy cracking at the weld due to insufficient magnesium content.

[0051] Furthermore, the range of a% is 0.15% to 4.8%. For example, a% can be 0.15%, 0.45%, 0.9%, 1.45%, 1.9%, 2.45%, 2.9%, 3.45%, 3.9%, 4.45%, 4.8%, etc. This embodiment does not limit the specific value of a%, and those skilled in the art can select it within the range of 0.15% to 4.8% according to their needs.

[0052] In a specific embodiment of this application, bmm ranges from 0.3mm to 3mm. For example, bmm can be 0.3mm, 0.5mm, 0.8mm, 1mm, 1.3mm, 1.5mm, 1.8mm, 2mm, 2.3mm, 2.5mm, 2.8mm, 3mm, etc. This embodiment does not limit the specific value of bmm; those skilled in the art can select a value within the range of 0.3mm to 3mm according to their needs.

[0053] This design avoids the problem that the welding energy cannot effectively melt the wall thickness of the first end face 120 in the welding area due to excessive wall thickness, resulting in low welding strength and easy cracking at the weld. It also avoids the problem that the pore size formed at the weld is too large in proportion to the wall thickness of the first end face 120 due to insufficient wall thickness in the welding area, resulting in poor sealing at the weld.

[0054] Furthermore, the range of bmm is 0.5mm to 2.5mm. For example, bmm can be 0.5mm, 0.7mm, 0.9mm, 1.1mm, 1.4mm, 1.6mm, 1.9mm, 2.1mm, 2.4mm, 2.5mm, etc. This embodiment does not limit the specific value of bmm; those skilled in the art can select it within the range of 0.5mm to 2.5mm according to their needs.

[0055] In a specific embodiment of this application, k ranges from 0.01 to 0.4. For example, k can be 0.01, 0.05, 0.08, 0.1, 0.15, 0.18, 0.2, 0.25, 0.3, 0.35, 0.4, etc. This embodiment does not limit the specific value of k; those skilled in the art can select a value within the range of 0.01 to 0.4 according to their needs.

[0056] This configuration avoids the risk of welding defects such as overmelting in some welding areas of the current collector 400 due to the large area ratio of the first weld mark 510 to the current collector 400, which would result in low welding strength. It also avoids the problem of poor sealing in the welding area due to the large proportion of porosity in the welding area caused by the first weld mark 510 occupying too small an area ratio of the current collector 400.

[0057] Furthermore, the range of k is 0.05 to 0.2. For example, k can be 0.05, 0.06, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, etc. This embodiment does not limit the specific value of k; those skilled in the art can select it within the range of 0.05 to 0.2 according to their needs.

[0058] In a specific embodiment of this application, the mass content of aluminum in the aluminum shell is c%, and the range of a / c is 0.001~0.054. For example, a / c can be 0.001, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.054, etc. This embodiment does not limit the specific value of a / c; those skilled in the art can select a value within the range of 0.001~0.054 according to their needs.

[0059] This configuration avoids the problem of insufficient aluminum content due to an excessively large a / c ratio, resulting in low strength of the outer shell 100; it also avoids the problem of insufficient magnesium content due to an excessively small a / c ratio, resulting in low strength of the welded area.

[0060] In one specific embodiment of this application, the mass content (c%) of aluminum in the aluminum shell ranges from 92% to 99.5%. For example, c% can be 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, etc. This embodiment does not limit the specific value of c%, and those skilled in the art can select a value within the range of 92% to 99.5% according to their needs.

[0061] In one specific embodiment of this application, the aluminum shell also contains manganese, with a manganese content ≥0.2% by mass, and the range of a% is 0.1% to 3.5%. For example, a% can be 0.1%, 0.4%, 0.8%, 1.2%, 1.4%, 1.6%, 1.9%, 2.3%, 2.8%, 3.2%, 3.5%, etc. This embodiment does not limit the specific value of a%, and those skilled in the art can select it within the range of 0.1% to 3.5% according to their needs.

[0062] Adding manganese to the aluminum shell can improve the strength of the weld between the first end face 120 and the current collector 400. However, the addition of manganese does not increase the porosity of the weld. However, the range for adjusting the amount of manganese added is limited, making it difficult to control and prone to overdosing, which can actually decrease the weld strength. Therefore, manganese cannot completely replace magnesium in improving weld strength. In this embodiment, the addition of manganese reduces the mass content of magnesium. Specifically, the mass content (a%) of magnesium is selected within the range of 0.1% to 3.5%, meaning that selecting a smaller value avoids the problem of excessive porosity at the weld due to excessive magnesium content, thus improving the sealing of the weld.

[0063] Furthermore, the mass content of manganese can be from 0.2% to 2.0%. For example, the mass content of manganese can be 0.2%, 0.4%, 0.8%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, etc. This embodiment does not limit the specific value of the mass content of manganese; those skilled in the art can select from the range of 0.2% to 2.0% according to their needs.

[0064] like Figure 2 As shown, in a specific embodiment of this application, the housing 100 includes a first end face 120 and a second end face 130 arranged opposite to each other, and a housing side face 230 located between the first end face 120 and the second end face 130.

[0065] The side portion 230 and the second end portion 130 of the housing are integrally formed, which reduces the welding process between the side portion 230 and the second end portion 130, reduces the number of manufacturing steps for the outer shell 100, and improves the manufacturing efficiency of the outer shell 100. Moreover, since the side portion 230 and the second end portion 130 of the housing are integrally formed, the strength of the outer shell 100 can also be improved.

[0066] The side portion 230 and the second end portion 130 of the housing form a receiving cavity for accommodating the battery cell 200. An opening is formed at the end of the receiving cavity away from the second end portion 130. The battery cell 200 can be inserted into the receiving cavity through this opening. The first end portion 120 is sealed to the opening and welded to the opening to form a second solder mark 520.

[0067] Furthermore, the range of a / (b×k) is 0.40 to 1047.83. For example, a / (b×k) can be 0.40, 1.00, 10.00, 50.00, 100.00, 160.00, 210.00, 310.00, 360.00, 410.00, 510.00, 560.00, 660.00, 720.00, 820.00, 920.00, 1047.83, etc. This embodiment does not limit the specific value of a / (b×k), and those skilled in the art can select it within the range of 0.40 to 1047.83 according to their needs.

[0068] In this embodiment, since the side portion 230 of the housing is only welded to the first end portion 120 and is integrally structured with the second end portion 130, the side portion 230 of the housing is only welded to the end portion (first end portion 120) on one side. The weld between the first end portion 120 and the side portion 230 of the housing will become a weak area of ​​the outer shell 100. In this embodiment, a / (b×k) can be selected in a large range to improve the strength of the first solder mark 510 between the first end portion 120 and the current collector 400 and avoid the failure of the first solder mark 510 connection.

[0069] For ease of understanding, in this embodiment, the projection of the first solder mark 510 onto the target plane is defined as the first projection, and the projection of the second solder mark 520 onto the target plane is defined as the second projection. The target plane is a plane parallel to the first end face 120. When the battery is a cylindrical battery, the target plane is a plane perpendicular to the axis of the circumferential battery.

[0070] It should be noted that the second end face 130 and the side face 230 of the housing can also be a separate structure, that is, the second end face 130 and the side face 230 of the housing are connected by welding. The connection strength between the second end face 130 and the side face 230 of the housing will be weaker than that of a one-piece structure. This can share the pressure of the first end face 120 and avoid the first end face 120 becoming a weak area, which could lead to the risk of failure of the first weld 510 between the current collector 400 and the first end face 120 under pressure.

[0071] like Figure 3 As shown, the shortest distance L1mm between the first projection and the second projection is 1mm to 8mm. For example, L1mm can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, etc. This embodiment does not limit the specific value of L1mm; those skilled in the art can select a value within the range of 1mm to 8mm according to their needs.

[0072] In this embodiment, the shortest distance between the first projection and the second projection is selected within the range of 1mm to 8mm. This avoids the problem of excessively concentrated welding heat in the areas where the first solder mark 510 and the second solder mark 520 are located due to the shortest distance being too small, resulting in over-melting and low welding strength. It also avoids the problem of the first solder mark 510 being too small due to the shortest distance being too large (since the position of the second solder mark 520 cannot be changed, in order to increase the distance between the first projection and the second projection, the first solder mark 510 needs to be adjusted in a direction away from the second solder mark 520, which will inevitably lead to a smaller area of ​​the first solder mark 510), thus affecting the current carrying capacity. This would result in severe heat generation during charge and discharge cycles, which could easily tear the metal layer on the surface of the pores at the weld between the first end face 120 and the current collector 400, causing the seal at the weld between the first end face 120 and the current collector 400 to fail.

[0073] In one specific embodiment of this application, the battery is cylindrical, i.e., it is a cylindrical battery. A cylindrical battery is a specific type of battery that can store chemical energy and controllably convert it into electrical energy. In recyclable batteries, the active materials can be reactivated by charging after discharge for continued use. When the battery is cylindrical, its outer casing 100 is cylindrical in shape; the inner surface of the outer casing 100 has a cylindrical receiving cavity.

[0074] In this embodiment, the battery diameter ranges from 20mm to 62mm, meaning the outer diameter of the casing 100 ranges from 20mm to 62mm. For example, the battery diameter can be 20mm, 22mm, 25mm, 28mm, 30mm, 32mm, 35mm, 38mm, 40mm, 42mm, 45mm, 48mm, 50mm, 52mm, 55mm, 58mm, 60mm, 62mm, etc. This embodiment does not limit the specific value of the battery diameter; those skilled in the art can select a value within the range of 20mm to 62mm according to their needs.

[0075] This design avoids the problem of low energy density due to an excessively small battery diameter, while also preventing the problem of excessive energy density and gas production due to an excessively large battery diameter, which could easily lead to sealing failure at the weld between the first end face 120 and the current collector 400.

[0076] like Figure 3 As shown, in a specific embodiment of this application, the current collector 400 is welded to the current output section of the battery cell 200, forming a third solder mark 530. Figures 5-7As shown, the second soldering position 420 of the current collector 400 is soldered to the current output section of the battery cell 200 to form a third solder mark 530. The second soldering position 420 of the current collector 400 can be closer to the center of the current collector 400 than the first soldering position 410 to facilitate soldering with the current output section of the battery cell 200.

[0077] like Figure 4 As shown, the battery cell 200 generally includes a battery cell body 210 and a tab portion 220 (i.e., a current output portion) extending towards the first end portion 120. It should be noted that the tab portion 220 extending towards the first end portion 120 may include only one of the first tab 221 and the second tab 222, or it may include both the first tab 221 and the second tab 222. One of the first tab 221 and the second tab 222 is the positive tab, and the other is the negative tab.

[0078] The positive and negative electrodes are key components of the battery, used to transmit and draw out the internal current of the cell 200. The material of the positive and negative electrodes can be the same as that of the current collector of the electrode sheet. For example, the positive and negative electrodes can be made of at least one of the following: silver-plated aluminum, silver-plated stainless steel, stainless steel, copper, aluminum, nickel, carbon, nickel, or titanium. Furthermore, the positive and negative electrodes can be cut from the current collector or can be separately formed metal parts. It is understood that the positive electrode is electrically connected to the positive electrode sheet in the cell, and the negative electrode is electrically connected to the negative electrode sheet in the cell.

[0079] In this embodiment, the current collector 400 refers to a current collector component that is simultaneously welded to both the first end face 120 and the current output portion of the battery cell 200. For example, if the outer casing 100 is the positive output portion of the battery, the current output portion of the battery cell 200 here refers to the negative electrode tab.

[0080] Furthermore, for ease of understanding, the projection of the first solder mark 510 onto the target plane is defined as the first projection, and the projection of the third solder mark 530 onto the target plane is defined as the third projection. The target plane is a plane parallel to the first end face 120. When the battery is a cylindrical battery, the target plane is a plane perpendicular to the axis of the circumferential battery.

[0081] like Figure 3As shown, in this embodiment, the first projection and the third projection are spaced apart, and the shortest distance between them, L2mm, is 2mm to 10mm. For example, L2mm can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, 10mm, etc. This embodiment does not limit the specific value of L2mm; those skilled in the art can select it within the range of 2mm to 10mm according to their needs.

[0082] This configuration avoids the problem of excessively long current paths due to excessively large short distances between the first and third projections, which would lead to severe overheating during charge and discharge cycles and easily tear the metal layer on the surface of the pores at the weld between the first end face 120 and the current collector 400, causing sealing failure at the weld between the first end face 120 and the current collector 400. It also avoids the problem of excessively small short distances between the first and third projections, which would lead to excessively close distances between the first weld mark 510 and the third weld mark 530, resulting in excessively concentrated welding heat and affecting welding strength.

[0083] In one specific embodiment of this application, the welding area of ​​the first solder mark 510 is smaller than the welding area of ​​the third solder mark 530. Since the welding areas of the first solder mark 510 and the third solder mark 530 can reflect the current-carrying capacity between the battery cell 200 and the casing 100, the larger the sum of the welding areas of the first solder mark 510 and the third solder mark 530, the stronger the current-carrying capacity between the battery cell 200 and the casing 100; conversely, the smaller the sum of the welding areas of the first solder mark 510 and the third solder mark 530, the weaker the current-carrying capacity between the battery cell 200 and the casing 100.

[0084] In this embodiment, while ensuring that the sum of the welding areas of the first solder mark 510 and the third solder mark 530 remains unchanged, the welding area of ​​the first solder mark 510 is designed to be smaller than that of the third solder mark 530, the welding area of ​​the third solder mark 530 (which does not require welding sealing) is made larger, and the welding area of ​​the first solder mark 510 (which requires welding sealing) is minimized. This ensures the current carrying capacity between the battery cell 200 and the casing 100 while avoiding the problem of excessive porosity and sealing failure caused by an excessively large welding area between the first end face 120 and the current collector 400.

[0085] It should be noted that, based on design requirements, those skilled in the art may also design the welding area of ​​the first solder mark 510 to be equal to the welding area of ​​the third solder mark 530; or design the welding area of ​​the first solder mark 510 to be greater than the welding area of ​​the third solder mark 530.

[0086] like Figure 3As shown, the first solder mark 510 is the solder mark formed when the first end face 120 is welded to the current collector 400, and the third solder mark 530 is the solder mark formed when the current collector 400 is welded to the current output part of the battery cell 200. When the first end face 120 is welded to the current collector 400, the welding equipment performs the welding on the side of the first end face 120 that is away from the current collector 400. In a specific embodiment of this application, the first solder mark 510 is closer to the side wall of the outer casing 100 than the third solder mark 530, that is, closer to the side wall of the outer casing body 110, in other words, closer to the edge side of the first end face 120.

[0087] Those skilled in the art will understand that welding gases are generated during welding. If the welding gases are not properly discharged, it will lead to the formation of more pores at the weld. In this embodiment, the first weld mark 510, which requires welding sealing, is arranged closer to the side wall of the outer casing 100. Since there is less obstruction closer to the side wall of the outer casing 100, the obstruction of welding gases by the structure on the first end face 120 can be reduced, facilitating the discharge of welding gases during the welding process, thereby reducing the formation of pores and improving the welding sealing performance.

[0088] like Figure 3 As shown, the first solder mark 510 and the third solder mark 530 have a height difference along a direction perpendicular to the first end face 120 (e.g., Figure 3 The height difference H between the first weld mark 510 and the third weld mark 530 along the direction perpendicular to the first end face 120 refers to the height difference H between the first welding position 410 and the second welding position 420 on the current collector 400 along the direction perpendicular to the first end face 120. The specific value of H is not limited in this embodiment, and those skilled in the art can choose it based on design requirements. In this embodiment, forming a height difference between the first weld mark 510 and the third weld mark 530 along the direction perpendicular to the first end face 120 can avoid heat concentration at the welding point, which would affect the weld strength.

[0089] In one specific embodiment of this application, the magnesium content of the current collector 400 is ≤1% by mass. For example, the magnesium content of the current collector 400 can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc. In this embodiment, magnesium is also added to the current collector 400 to improve the welding performance between the current collector 400 and the first end face 120. Simultaneously, the magnesium content of the current collector 400 is controlled to be below 1% to avoid excessive porosity at the weld between the first end face 120 and the current collector 400, which could affect the sealing performance.

[0090] It should be noted that the magnesium content of the current collector 400 can also be designed to be more than 1% as required. This embodiment does not limit the magnesium content of the current collector 400.

[0091] In one specific embodiment of this application, the battery is cylindrical, i.e., it is a cylindrical battery. Given that the battery is cylindrical, the ratio of the projected area of ​​the current collector 400 on the target plane to the area of ​​the cell end face is 0.4 to 0.95, where the cell end face is the end face of the cell 200 facing the first end face 120. For example, the above area ratio can be 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, etc. This embodiment does not limit the specific value of the above area ratio; those skilled in the art can select values ​​within the range of 0.4 to 0.95 according to their needs.

[0092] In this embodiment, the ratio of the projected area of ​​the current collector 400 on the target plane to the area of ​​the cell end face is designed to be in the range of 0.4 to 0.95, so that the current collector 400 has a large area, ensuring that it has better current carrying capacity, reducing the heat generation during charge and discharge cycles, reducing the risk of tearing the surface metal layer of the pores at the weld joint, and ensuring the sealing of the weld joint between the first end face 120 and the current collector 400.

[0093] like Figure 3 and Figure 4 As shown in a specific embodiment of this application, the battery is cylindrical, i.e., the battery is a cylindrical battery. Given that the battery is a cylindrical battery, the battery also includes an adapter 300. The adapter 300 and the current collector 400, as two core components of the current collector assembly, are disposed on the same end face of the cell 200.

[0094] The adapter 300 and the current collector 400 are electrically connected to the current output sections of the battery cell 200 of different polarities, respectively. The current output sections of the battery cell 200 of different polarities (one polarity is the positive electrode tab, and the other polarity is the negative electrode tab) also need to be led out from the same end. For example, the current collector 400 can be soldered to the positive electrode tab, and the adapter 300 to the negative electrode tab; alternatively, the current collector 400 can be soldered to the negative electrode tab, and the adapter 300 to the positive electrode tab.

[0095] When the adapter 300 and the current collector 400 are located on the same end face of the battery cell 200, both the positive and negative electrodes are heat sources, resulting in a higher temperature for the current collector 400. Therefore, the range of a / (b×k) is 0.12 to 980. For example, a / (b×k) can be 0.12, 1, 20, 70, 120, 170, 220, 320, 370, 450, 520, 570, 600, 670, 720, 820, 920, 980, etc. This embodiment does not limit the specific value of a / (b×k), and those skilled in the art can select a value within the range of 0.12 to 980 according to their needs.

[0096] In this embodiment, a / (b×k) is selected within a small range to reduce the number of pores at the weld between the first end face 120 and the current collector 400, thereby avoiding the risk of sealing failure due to the metal layer covering the pores being torn by high-temperature deformation.

[0097] It should be noted that the current collector 400 and the adapter 300 can also be located at different ends of the battery cell 200, depending on the lead-out direction of the tabs of the battery cell 200. If the positive and negative tabs of the battery cell 200 are led out from the same end, then the current collector 400 and the adapter 300 must be located at the same end of the battery cell 200; if the positive and negative tabs of the battery cell 200 are led out from two different ends, then the current collector 400 and the adapter 300 must be located at two different ends of the battery cell 200.

[0098] It should be noted that when the current collector 400 and the adapter plate 300 need to be located at the same end of the battery cell 200, the current collector assembly also includes a current collector insulating frame. The current collector 400 and the adapter plate 300 are mounted on the current collector insulating frame to achieve insulation between the current collector 400 and the adapter plate 300, and at the same time, to facilitate the fixing of the current collector 400 and the adapter plate 300, and to maintain the stability of the current collector 400 and the adapter plate 300.

[0099] like Figure 9 and Figure 10 As shown in a specific embodiment of this application, a groove 121 is formed on the first end face 120, and the welding area is located on the bottom wall of the groove 121. The groove 121 is located at the welding position between the first end face 120 and the current collector 400. During through welding, the molten metal can be constrained within the groove 121 to ensure the flatness of the surface of the first end face 120 away from the battery cell 200, preventing the molten metal from protruding from the surface of the first end face 120 and affecting the welding of the busbar, thus improving the current carrying capacity. At the same time, since the molten metal is located inside the groove 121, the sidewall of the groove 121 also constrains the width of the weld line, ensuring welding quality and improving welding strength.

[0100] While the groove 121 can constrain the welding position and improve welding quality to some extent, it can also affect the discharge of high-temperature gases during welding. Therefore, in this embodiment, the width of the groove 121 is ≥0.5mm, and the width of the groove 121 is the dimension along the width direction of the first weld mark 510. In this embodiment, the width of the groove 121 is designed to be ≥0.5mm to ensure that the high-temperature gases generated during welding can be discharged smoothly, reducing the probability of porosity and ensuring weld sealing.

[0101] like Figure 8 As shown, in a specific embodiment of this application, the shape of the first weld mark 510 is a closed ring structure (i.e., the shape of the first welding position 410 on the current collector 400 is a closed ring structure, such as a circle), meaning the area of ​​the first weld mark 510 is relatively large. In other words, the weld line length between the first end face 120 and the current collector 400 is relatively long, resulting in higher welding strength, but also a higher probability of weld porosity. Based on this, in this embodiment, a%≤4%, that is, the mass content of magnesium element is selected within a small range to reduce the number of pores generated at the weld between the first end face 120 and the current collector 400, thereby ensuring weld sealing.

[0102] like Figures 5-7 and Figure 11 As shown, the shape of the first weld mark 510 can also be a non-closed annular structure with a first end point 511 and a second end point 512 (that is, the shape of the first weld position 410 on the current collector 400 is a non-closed annular structure, such as an arc shape), and the circumferential distance between the first end point 511 and the second end point 512 is 20mm~130mm. The circumferential distance between the first end point 511 and the second end point 512 refers to the arc length of the first weld position 410, which can also be understood as the arc length of the first weld mark 510.

[0103] For example, the circumferential distance between the first endpoint 511 and the second endpoint 512 can be 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, etc. This embodiment does not limit the specific value of the circumferential distance between the first endpoint 511 and the second endpoint 512; those skilled in the art can select a value within the range of 20mm to 130mm according to their needs.

[0104] In this embodiment, the circumferential distance between the first endpoint 511 and the second endpoint 512 is selected within the range of 20mm to 130mm. This can avoid the problem of excessive pores and poor sealing caused by the circumferential distance being too long, and can also avoid the problem of insufficient welding strength and poor flow capacity caused by the circumferential distance being too short.

[0105] This application also discloses an electrical device, which includes the battery disclosed in the above embodiments. This electrical device can be an electric vehicle, electric ship, aircraft, energy storage device, etc. The electrical device disclosed in this application, having the aforementioned battery, possesses all the technical effects of that battery, which will not be elaborated upon further here.

[0106] The test method for k is as follows: Disassemble the battery, remove the first end face, and place it under an industrial camera (model: Gocator 4000X) for measurement. Measure the area of ​​the current collector from the side where it is located. This area is equal to the projected area of ​​the current collector on the target, denoted as S²mm. 2 The area of ​​the first weld mark where the first end face is welded to the current collector is measured from the side of the first end face away from the current collector. This area is equal to the projected area of ​​the first weld mark on the target and is denoted as S1mm. 2 , k=S1 / S2.

[0107] The test method for the wall thickness bmm at the welding area of ​​the first end face is as follows; Disassemble the battery, remove the first end face, and use a multimeter (accuracy 0.01mm) to measure the thickness of the first end face 1mm away from the first solder mark. Measure 3 times and take the average value, which is recorded as bmm.

[0108] The method for adjusting the wall thickness bmm at the welding area of ​​the first end face is as follows: The bmm value can be adjusted by cutting or impact extrusion molding the first end face.

[0109] The test method for magnesium content (a%) is as follows: Disassemble the battery and prepare a 5mm×5mm sample from the non-welded area of ​​the casing. Measure the mass content of magnesium in the sample according to GB / T7999-2015 (Direct Reading Photoelectric Emission Spectroscopy Analysis Method for Aluminum and Aluminum Alloys), and record it as a.

[0110] The method for adjusting the mass content (a%) of magnesium is as follows: The a% value can be adjusted by adding magnesium during smelting (the mass of magnesium added ranges from 2.1% to 10%). The more magnesium added, the larger the a% value, and the less magnesium added, the smaller the a% value. It can also be adjusted by smelting temperature (the smelting temperature range is 700 to 800℃). The higher the solution temperature, the smaller the a% value, and the lower the smelting temperature, the larger the a% value.

[0111] The outer shell mainly consists of aluminum, and may also include copper (0.05-0.2% by mass), iron (≤0.7% by mass), silicon (≤0.6% by mass), zinc (≤0.1% by mass), etc.

[0112] The battery casing is prepared as follows: Aluminum ingots are smelted in a tilting furnace to remove impurities and obtain a uniform molten aluminum. Magnesium is added during smelting to adjust the magnesium content to the required a% value. The molten aluminum is then cast into a plate at a temperature of 480-520℃. The plate is then hot-rolled at a temperature of 350-400℃ with a hot rolling reduction of 50%-60%. This is followed by multiple cold rolling passes. Before the final cold rolling, the plate is annealed (at a temperature of 340-360℃). After annealing, a final cold rolling is performed with a reduction of 20%-25%. This yields a blank plate, which is then heat-treated at 600-620℃ and annealed at 300-430℃ to obtain an aluminum plate. The aluminum plate is then used to produce a battery casing through stretching or impact extrusion molding.

[0113] This application also discloses a method for preparing a battery, the specific method of which is as follows.

[0114] (1) Preparation of the positive electrode: The prepared positive electrode active material, conductive agent (e.g., acetylene black), and binder (e.g., PVDF) are mixed, and NMP (N-Methylpyrrolidone) solvent 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 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.

[0115] Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98): (4~1): (4~1).

[0116] (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 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.

[0117] Specifically, the ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0118] (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.

[0119] (4) Preparation of the diaphragm: Polyethylene film is selected as the diaphragm.

[0120] (5) Preparation of lithium-ion batteries: The positive electrode, separator, and negative electrode are stacked in sequence and wound to form a battery cell. The first tab of the battery cell is welded to the current collector, and then placed in the battery casing. The current collector is then welded to the first end face of the casing to form the first solder mark. The battery is dried, injected with electrolyte, and then packaged, left to stand, formed, and volume-adjusted to obtain a lithium-ion battery.

[0121] In the selection of materials for the aforementioned battery, this application may also select other materials, not limited to those 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, Super P, carbon nanotubes, graphene, and carbon nanofibers. The binder in the positive electrode sheet may also be selected from one or more of polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan. The positive electrode current collector may also be selected from one or more of stainless steel with silver plating, stainless steel, aluminum, nickel, carbon electrode, carbon, nickel, and titanium. The positive electrode current collector may also include a composite current collector, which may include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming metallic materials (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on a polymer substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0122] 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 terephthalate, polyethylene terephthalate, polyethylene, etc.). The negative electrode active layer includes the negative electrode active material, conductive components, adhesives, etc.

[0123] This application discloses two performance testing methods, namely Test Method 1 and Test Method 2. Test Method 1 is a cyclic leakage test, and Test Method 2 is a thermal runaway weld cracking test. The specific test procedures for Test Method 1 and Test Method 2 are as follows.

[0124] Performance Test 1: Circulation Leakage Test.

[0125] Following the battery preparation method described above, 200 batteries were prepared for each of the embodiments and comparative examples. The values ​​of a, b, and k for the batteries in each embodiment are shown in Table 1 below. Apart from this, the other structures are the same. The batteries were charged at 1C to the upper limit voltage at 25°C, then charged at constant voltage to the cutoff current of 0.05C. After standing for 10 minutes, they were discharged at 1C to the lower limit voltage and stood for 10 minutes. This charging and discharging strategy was repeated 1000 times. The battery was observed to see if leakage occurred at the first solder joint. If leakage occurred, the number of leaking batteries was recorded as n. The percentage of leaking batteries was calculated using the formula: (n / 200) × 100%. If the percentage of leaking batteries was less than or equal to 1%, the battery was considered good. If the percentage of leaking batteries was greater than 1% and less than or equal to 3%, the battery was considered qualified. If the percentage of leaking batteries was greater than 3%, the battery was considered unqualified.

[0126] Different battery systems require corresponding adjustments to their upper and lower voltage limits: For cathode active materials including LFP (LiFePO4, lithium iron phosphate) – upper limit voltage 3.65V, lower limit voltage 2.5V; for cathode active materials including NCM (lithium nickel cobalt manganese oxide) – upper limit voltage 4.25V, lower limit voltage 2.5V; for cathode active materials including LFMP (lithium manganese iron phosphate) – upper limit voltage 4.25V, lower limit voltage 2.5V; for cathode active materials including lithium nickel manganese oxide – upper limit voltage 4.8V, lower limit voltage 3.5V.

[0127] 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, other positive electrode active materials all 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 other negative electrode active materials all meet the above test requirements, and the mass ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2.

[0128] Performance Test 2: Thermal Runaway Weld Cracking Test.

[0129] Following the battery preparation method described above, 200 batteries were prepared for each of the embodiments and comparative examples. The values ​​of a, b, and k for the batteries in each embodiment are shown in Table 1 below. Apart from this, the remaining structures are the same. The batteries were charged at 1C to the upper limit voltage at 25°C, and then charged at a constant voltage until the cutoff current was 0.05C. A heating wire was placed on the periphery of the battery to continuously heat the battery and trigger thermal runaway. When thermal runaway occurred, heating was stopped. After the thermal runaway ended, it was observed whether the weld at the first weld mark had cracked. If cracked, the number of batteries with cracked welds at the first weld mark was recorded as N. The weld cracking rate was calculated as (N / 200) × 100%. If the weld cracking rate was less than or equal to 2%, it was considered good. If the weld cracking rate was greater than 2% and less than or equal to 5%, it was considered qualified. If the weld cracking rate was greater than 5%, it was considered unqualified.

[0130] Different battery systems require corresponding adjustments to their upper and lower voltage limits: For cathode active materials including LFP (LiFePO4, lithium iron phosphate) – upper limit voltage 3.65V, lower limit voltage 2.5V; for cathode active materials including NCM (lithium nickel cobalt manganese oxide) – upper limit voltage 4.25V, lower limit voltage 2.5V; for cathode active materials including LFMP (lithium manganese iron phosphate) – upper limit voltage 4.25V, lower limit voltage 2.5V; for cathode active materials including lithium nickel manganese oxide – upper limit voltage 4.8V, lower limit voltage 3.5V.

[0131] The positive electrode active material used in this test was selected from LiNi. 0.6 Co 0.2 Mn0.2 Taking O2 as an example, other positive electrode active materials all 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 other negative electrode active materials all meet the above test requirements, and the mass ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2.

[0132] Table 1 Comparison of Leakage and Weld Cracking

[0133] As can be seen from Table 1, in Examples 1-2, 6-7, 9, and 11-19, the value of a / (b×k) ranges from 0.12 to 180.00, which meets the limit range of 0.12 to 1047.83 for a / (b×k), and is on the smaller side of the limit range. After testing, it can be seen that the leakage test is in good condition.

[0134] In Examples 3-5, 8, and 10, the value of a / (b×k) ranges from 187.45 to 1047.83, which satisfies the specified range of a / (b×k) from 0.12 to 1047.83. After testing, it can be seen that the leakage test is qualified.

[0135] In Examples 3-5, 8, and 10-19, the value of a / (b×k) ranges from 0.41 to 1047.83, which satisfies the limited range of a / (b×k) from 0.12 to 1047.83. After testing, it can be seen that the weld cracking test is in good condition.

[0136] In Examples 1-2, 6-7, and 9, the value of a / (b×k) ranges from 0.12 to 0.32, which satisfies the limited range of a / (b×k) from 0.12 to 1047.83. Moreover, it is a small value within the limited range. After testing, it can be seen that the weld cracking test is qualified.

[0137] In Examples 11-19, the value of a / (b×k) ranges from 0.41 to 180.00, which satisfies the limited range of a / (b×k) from 0.12 to 1047.83. After testing, it can be seen that the leakage test and the weld cracking test are both in good condition.

[0138] In Comparative Examples 1 and 3, the values ​​of a / (b×k) are 0.07 and 0.06, respectively, which do not meet the limit range of 0.12~1047.83 for a / (b×k) and are lower than the lower limit of the limit range. After testing, it can be seen that although the leakage test is qualified, the weld cracking test is unqualified.

[0139] In Comparative Examples 2 and 4, the values ​​of a / (b×k) are 1082.61 and 1171.11, respectively, which do not meet the limit range of 0.12~1047.83 for a / (b×k) and are higher than the upper limit of the limit range. After testing, it can be seen that although the weld cracking test is qualified, the leakage test is unqualified.

[0140] As illustrated in this application, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. An element defined by the phrase "comprising an..." does not exclude the presence of other identical elements in the process, method, product, or apparatus that includes the element.

[0141] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0142] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0143] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A battery, characterized in that, It includes a housing (100) and a battery cell (200) disposed within the housing (100), the housing (100) including a first end face (120); The first end face (120) is electrically connected to the current output section of the battery cell (200) through a current collector (400). The welding area of ​​the first end face (120) is welded to the current collector (400) to form a first solder mark (510). The projected area of ​​the first solder mark (510) on the target plane is S1mm. 2 The projected area of ​​the current collector (400) on the target is S2mm. 2 S1 / S2=k, the wall thickness of the first end face (120) at the welding area is bmm, the outer shell (100) includes an aluminum shell containing magnesium, and the mass content of magnesium is a%, a / (b×k) ranges from 0.12 to 1047.83, and the target plane is a plane parallel to the first end face (120).

2. The battery according to claim 1, characterized in that, The range of a% is 0.1% to 5%; And / or, The range of b is 0.3mm to 3mm.

3. The battery according to claim 1, characterized in that, The mass content of aluminum in the aluminum shell is c%, and the a / c ratio ranges from 0.001 to 0.

054.

4. The battery according to claim 1, characterized in that, The aluminum shell also contains manganese, with a manganese content of ≥0.2% by mass and a% ranging from 0.1% to 3.5%.

5. The battery according to claim 1, characterized in that, The outer casing (100) includes a second end portion (130) arranged opposite to the first end portion (120) and a side portion (230) of the casing located between the first end portion (120) and the second end portion (130). The side portion (230) of the housing and the second end portion (130) are integrally formed and together form a receiving cavity for accommodating the battery cell (200). The receiving cavity has an opening at one end away from the second end portion (130). The first end portion (120) is sealed in the opening and welded to the opening to form a second solder mark (520).

6. The battery according to claim 5, characterized in that, The range of a / (b×k) is 0.40~1047.

83.

7. The battery according to claim 5, characterized in that, The projection of the first solder mark (510) on the target plane is the first projection, and the projection of the second solder mark (520) on the target plane is the second projection; The shortest distance L1mm between the first projection and the second projection is 1mm to 8mm.

8. The battery according to any one of claims 1-7, characterized in that, The battery is cylindrical, and its diameter ranges from 20mm to 62mm.

9. The battery according to any one of claims 1-7, characterized in that, The battery is cylindrical, and the ratio of the projected area of ​​the current collector (400) on the target plane to the area of ​​the cell end face is 0.4~0.

95. The cell end face is the end face of the cell (200) facing the first end face (120).

10. The battery according to any one of claims 1-5 and 7, characterized in that, The battery is cylindrical and includes an adapter (300). The adapter (300) and the current collector (400) are disposed on the same end face of the cell (200) and are electrically connected to the current output section of the cell (200) of different polarities respectively. The range of a / (b×k) is 0.12~980.

11. The battery according to any one of claims 1-7, characterized in that, The current collector (400) is welded to the current output section of the battery cell (200) to form a third solder mark (530).

12. The battery according to claim 11, characterized in that, The projection of the first solder mark (510) onto the target plane is the first projection, and the projection of the third solder mark (530) onto the target plane is the third projection. The target plane is a plane parallel to the first end face (120). The shortest distance L2mm between the first projection and the third projection is 2mm to 10mm.

13. The battery according to claim 11, characterized in that, The welding area of ​​the first solder mark (510) is smaller than the welding area of ​​the third solder mark (530).

14. The battery according to claim 11, characterized in that, The first solder mark (510) is closer to the sidewall of the outer casing (100) than the third solder mark (530).

15. The battery according to claim 11, characterized in that, The first solder mark (510) and the third solder mark (530) have a height difference along a direction perpendicular to the first end face (120).

16. The battery according to any one of claims 1-7, characterized in that, The mass content of magnesium in the current collector (400) is ≤1%.

17. The battery according to any one of claims 1-7, characterized in that, The range of k is 0.01 to 0.

4.

18. The battery according to any one of claims 1-7, characterized in that, The first end face (120) has a groove (121) formed thereon, and the welding area is located on the bottom wall of the groove (121).

19. The battery according to claim 18, characterized in that, The width of the groove (121) is ≥0.5mm, and the width of the groove (121) is the dimension along the width direction of the first solder mark (510).

20. The battery according to any one of claims 1-7, characterized in that, The first solder mark (510) has a closed ring structure, and a%≤4%.

21. The battery according to any one of claims 1-7, characterized in that, The first solder mark (510) is a non-closed ring structure with a first end point (511) and a second end point (512), and the circumferential distance between the first end point (511) and the second end point (512) is 20mm~130mm.

22. An electrical appliance, characterized in that, Includes the battery as described in any one of claims 1-21.

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