A battery, a battery pack, and an electric device

Abstract

The application discloses a battery, a battery pack and a power utilization device, relates to the technical field of batteries, and comprises a pole, a shell and a battery core, the battery core comprises a battery core body and a battery core output end, the shell comprises a shell main body provided with an opening at one end and a battery cover plate, the pole is arranged on the battery cover plate and is welded to the battery core output end to form a first welding mark, and the battery cover plate is welded to the opening end of the shell main body and forms a second welding mark; the minimum heat transfer path length from the first welding mark to the second welding mark is X mm, the volume energy density of the battery is Y Wh / L, and the range of Y / X is 5.83-123.8. According to the application, the volume energy density of the battery and the minimum heat transfer path length from the first welding mark to the second welding mark are comprehensively regulated, Y / X is in the range of 5.83-123.8, the cracking risk of the welding seam between the shell main body and the battery cover plate can be effectively reduced while the overcurrent capacity of the battery is ensured, and the risks of fire, explosion and the like caused by the cracking risk can be reduced.

Description

Technical Field

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

[0002] A battery mainly consists of a casing and the battery cells housed within it. The casing typically comprises a main body and a battery cover that seals the open end of the main body. Currently, in common battery designs, the welded connection between the main body and the battery cover often suffers from insufficient reliability. During use, the weld between the main body and the battery cover is prone to cracking, causing the battery cover to separate from the main body. This defect significantly increases the battery's pressure relief area, potentially triggering a rapid thermal runaway reaction, significantly increasing the risk of fire, explosion, and other safety accidents, seriously threatening battery safety.

[0003] Therefore, how to prevent the weld between the main body of the casing and the battery cover from cracking, and reduce the risk of fire and explosion caused by it, 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 to prevent the weld between the casing body and the battery cover from cracking, thereby reducing the risk of fire, explosion and other problems caused therefrom. Another object of this application is to provide a battery pack and an electrical device having the above-mentioned battery.

[0005] To achieve the above objectives, this application provides the following technical solution: The first aspect of this application provides a battery, including terminals, a housing, and a cell located inside the housing. The cell includes a cell body and a cell output terminal. The housing includes a housing body with an opening at one end and a battery cover. The terminals are disposed on the battery cover and welded to the cell output terminal to form a first weld mark. The battery cover is welded to the opening end of the housing body to form a second weld mark. The minimum heat transfer path length from the first solder mark to the second solder mark is X mm, the volumetric energy density of the battery is Y Wh / L, and the range of Y / X is 5.83~123.8.

[0006] The battery disclosed in the above technical solution selects the ratio of the battery's volumetric energy density to the minimum heat transfer path length from the first solder mark to the second solder mark within the range of 5.83 to 123.8. This avoids the problem that if the ratio is too large, the volumetric energy density of the battery will be too high, resulting in severe heat generation during battery thermal runaway. On the other hand, if the minimum heat transfer path length from the first solder mark to the second solder mark is too small, the heat at the connection between the terminal and the cell output end (i.e., the heat at the first solder mark) will be quickly transferred to the welding line between the battery cover and the main body of the casing (i.e., the second solder mark), which will easily cause the welding line between the battery cover and the main body of the casing to crack.

[0007] The battery disclosed in the above technical solution selects the ratio of the battery's volumetric energy density to the minimum heat transfer path length from the first solder mark to the second solder mark within the range of 5.83 to 123.8. This can also avoid the situation where the ratio is too small, resulting in a low volumetric energy density and an excessively long minimum heat transfer path length from the first solder mark to the second solder mark. If the position of the terminal remains unchanged, this would result in an excessively small area of ​​the welding region between the terminal and the cell output end (i.e., the area of ​​the first solder mark needs to be reduced to increase the minimum heat transfer path length from the first solder mark to the second solder mark), leading to poor current carrying capacity from the cell to the terminal.

[0008] The battery disclosed in the above technical solution, by comprehensively controlling the volumetric energy density of the battery and the minimum heat transfer path length from the first weld to the second weld, and keeping the ratio of the two in the range of 5.83 to 123.8, can effectively reduce the risk of cracking of the weld between the main body of the casing and the battery cover plate while ensuring the battery's overcurrent capacity, thereby reducing the risk of fire, explosion and other risks caused by it.

[0009] A second aspect of this application provides a battery pack comprising at least two batteries, the batteries being batteries as described above, the housing body comprising a first surface and a second surface, the area of ​​the first surface being larger than the area of ​​the second surface, and the at least two batteries being arranged in a direction perpendicular to the first surface.

[0010] The battery pack disclosed in the above technical solution has all the technical effects of the battery mentioned above, and will not be repeated here.

[0011] A third aspect of this application provides an electrical device that includes a battery pack as described above.

[0012] The electrical device disclosed in the above technical solution has all the technical effects of the battery pack, and will not be described in detail here. Attached Figure Description

[0013] 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.

[0014] 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 for Figure 2 A magnified view of part A in the image; Figure 4 for Figure 2 A magnified view of part B in the image; Figure 5 This is a schematic diagram of the battery cell disclosed in the embodiments of this application; Figure 6 This is a schematic diagram of the first wall surface disclosed in an embodiment of this application; Figure 7 This is a partial cross-sectional view of the battery disclosed in an embodiment of this application; Figure 8 This is a top view of the battery cover disclosed in an embodiment of this application; Figure 9 This is a top view of a battery cover disclosed in another embodiment of this application; Figure 10 This is a magnified view of a weak point disclosed in an embodiment of this application; Figure 11 This is a schematic diagram of the battery pack structure disclosed in an embodiment of this application.

[0015] The meanings of the various reference numerals in the figure are as follows: 000 - Battery; 100 - Housing; 110 - Housing body; 120 - Battery cover; 200-pole column; 300 - Explosion-proof valve; 310 - Weak section; 311 - Straight section; 312 - Curved section; 301 - Groove; 400 - Battery cell; 410 - Battery cell output terminal; 510 - First solder mark; 520 - Second solder mark; 600 - Insulating component; 610 - Upper insulating component; 620 - Lower insulating component. Detailed Implementation

[0016] This application discloses a battery to prevent the weld between the casing body and the battery cover from cracking, thereby reducing the risk of fire, explosion, etc. Another embodiment of this application discloses a battery pack and an electrical device having the above-described battery.

[0017] 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.

[0018] In existing technologies, battery casings generally include a casing body with an opening at one end and a battery cover plate for sealing the opening of the casing body. The casing body and the battery cover plate are fixed together by welding. The welded joints are prone to cracking under high-temperature conditions, leading to severe thermal runaway of the battery, posing a risk of fire and explosion, and seriously affecting the safety of battery use.

[0019] Research indicates that cracking in the welded area (i.e., the weld seam) between the battery casing and the battery cover is primarily due to the rapid decrease in the weld's ultimate stress under high-temperature conditions. In other words, the ultimate stress of the weld seam between the casing and the battery cover varies at different temperatures; the higher the temperature, the lower the ultimate stress, and the more prone it is to cracking. Conversely, as the battery temperature increases, the weld seam between the casing and the battery cover is more susceptible to cracking.

[0020] The terminals in a battery, as the primary current-carrying components, are the core heat source; especially at their connection to the cell output end, heat is concentrated due to the higher contact resistance. During normal battery use, the weld between the battery casing and the battery cover is continuously affected by the high temperature at the connection between the terminals and the cell output end. When the battery enters a thermal runaway state, the heat accumulated at the terminal-cell connection is rapidly transferred to the weld area, causing a sharp rise in weld temperature and further reducing the ultimate stress for weld cracking. Furthermore, with increasing demands for battery range, the volumetric energy density of batteries increases accordingly, leading to increased overall heat generation. This also results in even higher temperatures during thermal runaway, further exacerbating the risk of weld cracking.

[0021] The applicant discovered through research that by comprehensively controlling the minimum heat transfer path length from the connection between the electrode post and the cell output end to the weld and the volumetric energy density of the battery, and keeping the ratio of the two within a limited range, the risk of cracking of the weld between the casing body and the battery cover plate can be effectively reduced while ensuring the battery's overcurrent capacity (or maintaining a high energy density).

[0022] like Figures 1-5As shown, the battery disclosed in this application includes a terminal post 200, a casing 100, and a cell 400 located inside the casing 100. The casing also contains an electrolyte.

[0023] The battery cell 400 is the component in the battery where electrochemical reactions occur; it is the smallest unit in the battery capable of performing electrochemical reactions such as charging / discharging. The battery cell 400 includes the cell body and the cell output terminal 410. The cell body generally includes a positive electrode and a negative electrode, with a separator between them. The battery cell 400 can be a wound core or a stacked core. The main cell shapes include cylindrical cells and cuboid cells.

[0024] Lithium-ion cells mainly rely on the intercalation and deintercalation of lithium ions between the positive and negative electrodes to function.

[0025] The positive electrode is one of the core components in a battery that carries the positive electrode active material. During charging, metal ions (e.g., 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 (e.g., 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.

[0026] A positive electrode generally comprises 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 electrode active materials in 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 fO2, 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.

[0027] The positive electrode current collector includes a conductive metal foil, which can be made of silver-plated stainless steel, non-silver-plated stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. 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 polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0028] 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.

[0029] 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.

[0030] The negative electrode includes a negative current collector and a negative active layer disposed on at least one surface of the negative current collector. The negative current collector is a conductive metal foil, which can be made of silver-plated stainless steel, non-silver-plated stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. The negative 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.).

[0031] 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.

[0032] 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.

[0033] The output terminal of a battery cell is generally a tab assembly (the tab assembly may consist only of tabs, or it may include tabs and adapter plates). Depending on the polarity, the tab assembly generally includes a positive tab assembly and a negative tab assembly. The positive tab assembly is electrically connected to the positive output terminal (such as the positive terminal post) of the battery's electrical connection output terminal, and the negative tab assembly is electrically connected to the negative output terminal (such as the negative terminal post) of the electrical connection output terminal.

[0034] As a key component of a battery, the tab assembly is used to transmit and extract the current from the battery cell. The material of the tab assembly can be the same as that of the current collector (positive current collector for the positive electrode / negative current collector for the negative electrode) in the battery cell. For example, the tab can be made of at least one of the following: silver-plated aluminum, silver-plated stainless steel, stainless steel, copper, aluminum, nickel, carbon, or titanium. Furthermore, the tab can be cut from the current collector or it can be a separately formed metal part. It is understood that the positive tab is electrically connected to the positive electrode in the battery cell, and the negative tab is electrically connected to the negative electrode in the battery cell.

[0035] The tab assembly is separately or integrally formed with the positive / negative current collector, and is electrically connected to the current collector to conduct current from the corresponding current collector. When the tab assembly and the current collector are separately arranged, the tab assembly and the current collector can be connected by welding. The tab assembly is made of a metal material with good conductivity (such as copper, aluminum, or nickel).

[0036] 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 acid 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.

[0037] The housing 100 is a component used to provide a receiving space to house electrode assemblies and other parts 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 battery cover 120. The housing 100 is an external protective structure for the battery cell 400, used to house the battery cell 400 and isolate it from the external environment; the material of the housing 100 includes at least one of copper, iron, aluminum, steel, aluminum alloy, titanium, etc. Typically, the battery cover 120 is welded to the open end of the housing body 110, forming a second weld mark 520. For example, the housing 100 is made of aluminum alloy, where the aluminum content can range from 95% to 99%. Alternatively, the housing 100 can also be made of steel or titanium. Because steel or titanium has higher strength, under the same structural conditions, an aluminum alloy housing 100 meets the requirements, and a steel or titanium housing 100 also meets the strength requirements.

[0038] One end of the housing body 110 is an open end to facilitate the installation of the battery cell 400 inside the housing 100 through this open end. To close the opening of the housing body 110, a battery cover 120 is used. That is, the battery cover 120 is a component that covers the opening of the housing body 110 to isolate the housing space of the battery cell 400 from the external environment. The shape of the battery cover 120 can be adapted to the shape of the housing body 110 to fit the housing body 110. The battery cover 120 can be made of a material with a certain hardness and strength (such as aluminum alloy). The shape of the housing 100 can be determined according to the specific shape and size of the battery cell 400. The material of the housing 100 can be various, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0039] The terminal post 200 is disposed on the battery cover plate 120 and welded to the cell output end 410 to form a first solder mark 510. The cell output end 410 may or may not face the battery cover plate 120. When the cell output end 410 does not face the battery cover plate 120, the cell output end 410 is disposed towards the side wall of the housing body 110 adjacent to the battery cover plate 120. In this case, the cell output end 410 can be electrically connected to the terminal post 200 through an adapter piece.

[0040] The pole piece 200 is a structure in which one end is electrically connected to the output end of the battery cell and the other end is electrically connected to an external output end (such as a busbar) to output the electrical energy of the battery cell to the outside. The material of the pole piece 200 is generally a metal material such as aluminum, aluminum alloy, copper, or copper-aluminum alloy.

[0041] Terminal 200 is used to electrically connect the electrode assembly (cell 400) 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 assembly) and terminal 200, and an external power source can charge the battery through terminal 200 and the cell output terminal (tab assembly). Terminal 200 can be directly electrically connected to the tabs or electrically connected to the tabs through an adapter.

[0042] The pole piece 200 is made of metal materials including but not limited to copper, aluminum, aluminum alloy, and copper-aluminum alloy.

[0043] One end of the adapter is used for electrical connection to the output terminal (tab) of the battery cell, and the other end is used for electrical connection to the output terminal (terminal 200) of the battery, so that current flows between the tab and the terminal 200. The adapter is made of at least one of the following conductive metals: aluminum, aluminum alloy, etc. The specific material of the adapter is selected according to the materials of the battery's terminal 200 and tab.

[0044] In this embodiment, the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520 is X mm. It should be noted that the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520 refers to the minimum path length along which the heat generated by the first solder mark 510 is conducted to the second solder mark 520 along the wall of the housing 100, and not the straight-line distance between the first solder mark 510 and the second solder mark 520.

[0045] When the end face of the pole post 200 where the first solder mark 510 is located is on the same plane as the end face of the battery cover plate 120 near the cell, the minimum heat transfer path length Xmm from the first solder mark 510 to the second solder mark 520 is equal to the minimum distance from the first solder mark 510 to the second solder mark 520 on the plane where the battery cover plate 120 is located. When the end face of the electrode post 200 where the first solder mark 510 is located protrudes from the end face of the battery cover plate 120 near the cell side, the minimum heat transfer path length Xmm from the first solder mark 510 to the second solder mark 520 is equal to the sum of the distance from the end face of the electrode post where the first solder mark 510 is located to the plane where the battery cover plate 120 is located and the minimum distance between the projection of the first solder mark 510 on the plane where the battery cover plate 120 is located and the second solder mark 520.

[0046] The volumetric energy density of the battery is YWh / L. Volumetric energy density refers to the ratio of battery capacity to battery volume. A higher volumetric energy density means that more energy can be stored in the same space. In this embodiment, Y / X ranges from 5.83 to 123.8.

[0047] For example, Y / X can be 5.83, 6, 14, 23, 31, 40, 48, 56, 65, 73, 82, 90, 99, 107, 115, 123.8, etc. This embodiment does not limit the specific value of Y / X, and those skilled in the art can select it within the range of 5.83 to 123.8 according to their needs.

[0048] The battery disclosed in this application selects the ratio of the battery's volumetric energy density to the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520 within the range of 5.83 to 123.8. This avoids the situation where the ratio is too large, resulting in an excessively high volumetric energy density and severe heat generation during thermal runaway. Conversely, it avoids the situation where the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520 is too small, causing the heat at the connection between the terminal post 200 and the cell output end (i.e., the heat at the first solder mark 510) to be rapidly transferred to the welding line between the battery cover plate 120 and the housing body 110 (i.e., the second solder mark 520), leading to the problem that the welding line between the battery cover plate 120 and the housing body 110 is prone to cracking.

[0049] The battery disclosed in this application selects the ratio of the battery's volumetric energy density to the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520 within the range of 5.83 to 123.8. This avoids the situation where the ratio is too small, resulting in a low volumetric energy density and an excessively long minimum heat transfer path length from the first solder mark 510 to the second solder mark 520. If the position of the terminal post 200 remains unchanged, the area of ​​the welding region between the terminal post 200 and the cell output end will be too small (i.e., the area of ​​the first solder mark 510 needs to be reduced to increase the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520), leading to poor current carrying capacity from the cell 400 to the terminal post 200.

[0050] The battery disclosed in this application, by comprehensively controlling the volumetric energy density of the battery and the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520, and keeping the ratio of the two in the range of 5.83 to 123.8, can effectively reduce the risk of cracking of the weld between the main body of the casing 110 and the battery cover plate 120 while ensuring the battery's overcurrent capacity, thereby reducing the risk of fire, explosion and other risks caused by it.

[0051] In one specific embodiment of this application, the minimum heat transfer path length Xmm from the first solder mark 510 to the second solder mark 520 can be 8mm to 40mm. For example, Xmm can be 8mm, 11mm, 14mm, 17mm, 20mm, 23mm, 26mm, 29mm, 32mm, 35mm, 38mm, 40mm, etc. This embodiment does not limit the specific value of Xmm; those skilled in the art can select a value within the range of 8mm to 40mm according to their needs.

[0052] This design avoids the problem that if Xmm is too small, the heat at the connection between the terminal 200 and the cell output end (i.e., the heat at the first solder mark 510) will be quickly transferred to the welding line between the battery cover 120 and the housing body 110 (i.e., the second solder mark 520), causing the welding line between the battery cover 120 and the housing body 110 to be prone to cracking. It also avoids the problem that if Xmm is too large, the area of ​​the welding area between the terminal 200 and the cell output end will be too small when the position of the terminal 200 remains unchanged (i.e., the area of ​​the first solder mark 510 needs to be reduced to increase the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520), resulting in poor current carrying capacity from the cell 400 to the terminal 200.

[0053] Preferably, the range of Xmm can be 10mm to 30mm. For example, Xmm can be 10mm, 12mm, 15mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, etc. This embodiment does not limit the specific value of Xmm; those skilled in the art can select a value within the range of 10mm to 30mm according to their needs.

[0054] In one specific embodiment of this application, the volumetric energy density (YWh / L) of the battery can be between 200Wh / L and 1000Wh / L. For example, YWh / L can be 200Wh / L, 300Wh / L, 400Wh / L, 500Wh / L, 600Wh / L, 700Wh / L, 800Wh / L, 850Wh / L, 900Wh / L, 930Wh / L, 960Wh / L, 1000Wh / L, etc. This embodiment does not limit the specific value of YWh / L; those skilled in the art can select it within the range of 200Wh / L to 1000Wh / L according to their needs. This setting avoids the problem of severe heat generation during battery thermal runaway due to excessively high YWh / L, and also avoids the problem of high internal resistance and poor overcurrent capacity due to excessively low YWh / L.

[0055] Preferably, the range of YWh / L can be 280Wh / L to 800Wh / L. For example, YWh / L can be 280Wh / L, 320Wh / L, 360Wh / L, 420Wh / L, 480Wh / L, 550Wh / L, 650Wh / L, 750Wh / L, 800Wh / L, etc. This embodiment does not limit the specific value of YWh / L; those skilled in the art can select a value within the range of 280Wh / L to 800Wh / L according to their needs.

[0056] In one specific embodiment of this application, the battery capacity can range from 50Ah to 650Ah. For example, the battery capacity can be 50Ah, 100Ah, 150Ah, 200Ah, 250Ah, 300Ah, 350Ah, 400Ah, 450Ah, 500Ah, 550Ah, 650Ah, etc. This embodiment does not limit the specific value of the battery capacity; those skilled in the art can select from the range of 50Ah to 650Ah according to their needs.

[0057] Taking a prismatic battery as an example, the battery length can range from 140mm to 320mm. For instance, the battery length can be 140mm, 160mm, 180mm, 200mm, 220mm, 240mm, 260mm, 280mm, 290mm, 300mm, 310mm, 320mm, etc. This embodiment does not limit the specific value of the battery length; those skilled in the art can select a length within the range of 140mm to 320mm according to their needs.

[0058] The width of the battery can range from 20mm to 76mm. For example, the battery width can be 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 76mm, etc. This embodiment does not limit the specific value of the battery width; those skilled in the art can select a value within the range of 20mm to 76mm according to their needs.

[0059] The height of the battery can range from 70mm to 250mm. For example, the battery height can be 70mm, 90mm, 110mm, 130mm, 150mm, 170mm, 190mm, 210mm, 220mm, 230mm, 240mm, 250mm, etc. This embodiment does not limit the specific value of the battery height; those skilled in the art can select a value within the range of 70mm to 250mm according to their needs.

[0060] Based on this, the range of YWh / L can be further preferably 300Wh / L to 550Wh / L. For example, YWh / L can be 300Wh / L, 320Wh / L, 340Wh / L, 360Wh / L, 380Wh / L, 400Wh / L, 420Wh / L, 440Wh / L, 460Wh / L, 480Wh / L, 500Wh / L, 550Wh / L, etc. This embodiment does not limit the specific value of YWh / L; those skilled in the art can select a value within the range of 300Wh / L to 550Wh / L according to their needs.

[0061] In one specific embodiment of this application, the range of Y / X can be 10.05 to 75. For example, Y / X can be 10.05, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, etc. This embodiment does not limit the specific value of Y / X; those skilled in the art can select a value within the range of 10.05 to 75 according to their needs.

[0062] In one specific embodiment of this application, the battery is a prismatic battery / a cuboid battery, and the battery cover 120 is a rectangular structure. All four sides of the battery cover 120 are welded to the main body 110 of the casing. That is, the second weld mark 520 includes a long side weld line located on the long side of the battery cover 120 and a short side weld line located on the short side of the battery cover 120.

[0063] For ease of understanding, the heat transfer path length from the first solder mark 510 to the long side solder wire is defined as the first path length, and the heat transfer path length from the first solder mark 510 to the short side solder wire is defined as the second path length. In this embodiment, the first path length is less than the second path length; in other words, the heat transfer path length from the first solder mark 510 to the long side solder wire is less than the heat transfer path length to the short side solder wire. That is, in the heat transfer path from the first solder mark 510 to the second solder mark 520, the first solder mark 510 is closer to the long side solder wire.

[0064] The larger surfaces (i.e., the sides with larger areas) of the main body 110 of the housing experience greater thermal expansion, meaning the risk of cracking of the long-side weld line of the second solder mark 520 is higher. Therefore, in this embodiment, X ranges from 10mm to 35mm. For example, in this embodiment, Xmm can be 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 35mm, etc. This embodiment does not limit the specific value of Xmm; those skilled in the art can select a value within the range of 10mm to 35mm according to their needs.

[0065] In this embodiment, the length of the minimum heat transfer path from the first solder mark 510 to the second solder mark 520 (i.e., the heat transfer path of the long side solder wire from the first solder mark 510 to the second solder mark 520) is selected from a larger value. That is, the area of ​​the first solder mark 510 is reduced, so that the minimum heat transfer path from the first solder mark 510 to the second solder mark 520 is increased. This avoids the problem of the heat from the electrode post 200 and the cell output end 410 being quickly transferred to the long side solder wire of the second solder mark 520, which could cause the long side solder wire to crack.

[0066] When the battery is cylindrical, the Y / X range can be 10~123.8. Cylindrical batteries do not have the corner where the long side weld line connects to the short side weld line like prismatic batteries. The overall strength of the second weld mark 520 is better, and the casing strength of cylindrical batteries is higher than that of prismatic batteries. Therefore, Y / X can be selected in a larger range to reduce the battery's internal resistance, increase the battery's overcurrent capacity, and avoid excessively high temperatures during high-rate charging and discharging, which would affect battery safety.

[0067] Furthermore, the difference between the first path length and the second path length (difference between the first path length and the second path length = second path length - first path length) ranges from 10mm to 100mm. For example, in this embodiment, the difference between the first path length and the second path length can be 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 85mm, 90mm, 95mm, 100mm, etc. This embodiment does not limit the specific value of the difference between the first path length and the second path length; those skilled in the art can select a value within the range of 10mm to 100mm according to their needs.

[0068] This configuration avoids the problem that if the difference is too large, the heat transfer path from the first solder mark 510 to the long side solder wire will be too short, or the heat transfer path from the first solder mark 510 to the short side solder wire will be too long, causing the heat from the electrode post 200 and the cell output end 410 to be concentrated on the long side solder wire, increasing the risk of cracking of the long side solder wire. It also avoids the problem that if the difference is too small, the heat transfer path from the first solder mark 510 to the short side solder wire will be too short, causing the heat from the electrode post 200 and the cell output end 410 to be transferred to the short side solder wire, increasing the risk of cracking of the short side solder wire.

[0069] In one specific embodiment of this application, the battery cover 120 has a rectangular structure, and all four sides of the battery cover 120 are welded to the housing body 110. That is, the second weld mark 520 includes a long side weld line located on the long side of the battery cover 120 and a short side weld line located on the short side of the battery cover 120.

[0070] For ease of understanding, the heat transfer path length from the first solder mark 510 to the long side solder wire is defined as the first path length, and the heat transfer path length from the first solder mark 510 to the short side solder wire is defined as the second path length. In this embodiment, the first path length is greater than the second path length. In other words, the heat transfer path length from the first solder mark 510 to the long side solder wire is greater than the heat transfer path length to the short side solder wire. That is, on the heat transfer path from the first solder mark 510 to the second solder mark 520, the first solder mark 510 is closer to the short side solder wire.

[0071] This configuration extends the coverage area of ​​the first solder mark 510 towards the short side of the battery cover 120. For example, the first solder mark 510 can be designed as a long strip structure, thereby increasing its area and improving the current carrying capacity from the cell 400 to the terminal 200. Since the large surface area expansion in the side of the casing is significant, the risk of cracking of the long side solder line of the second solder mark 520 is greater. In this embodiment, the first solder mark 510 is designed closer to the short side solder line, which can partially distribute the heat generated at the first solder mark 510 to the short side solder line, reducing the impact on the long side solder line and preventing cracking of the long side solder line.

[0072] like Figure 6 As shown in a specific embodiment of this application, for ease of understanding, the area of ​​the first solder mark 510 is defined as the first area. The area of ​​the first solder mark 510 refers to the projected area on a plane parallel to the large surface of the first solder mark 510.

[0073] The area of ​​the electrode post 200 near the surface of the cell 400 is defined as the second area, and the ratio of the first area to the second area ranges from 0.07 to 0.75. For example, in this embodiment, the ratio of the first area to the second area can be 0.07, 0.12, 0.17, 0.22, 0.27, 0.32, 0.37, 0.42, 0.47, 0.52, 0.57, 0.75, etc. This embodiment does not limit the specific value of the ratio of the first area to the second area; those skilled in the art can select a value within the range of 0.07 to 0.75 according to their needs.

[0074] This configuration avoids the problem of the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520 being too short due to an excessively large ratio of the first area to the second area, causing the heat from the terminal 200 and the cell output end 410 to be quickly transferred to the welding wires of the battery cover 120 and the housing body 110, resulting in cracking of the welding wires of the battery cover 120 and the housing body 110; it also avoids the problem of the current-carrying area being too small due to an excessively small ratio of the first area to the second area, resulting in poor current-carrying capacity from the cell 400 to the terminal 200.

[0075] The first area can be 5mm. 2 ~215mm 2 For example, in this embodiment, the first area can be 5 mm². 2 20mm 2 40mm 2 60mm 2 80mm 2 100mm 2 120mm 2 140mm 2 160mm 2180mm 2 200mm 2 215mm 2 Etc. This embodiment does not limit the specific value of the first area; those skilled in the art can adjust it according to requirements, such as within 5mm. 2 ~215mm 2 Choose from the range.

[0076] The second area can be 63mm. 2 ~404mm 2 For example, in this embodiment, the second area can be 63 mm². 2 80mm 2 130mm 2 180mm 2 240mm 2 300mm 2 350mm 2 400mm 2 404mm 2 Etc. This embodiment does not limit the specific value of the second area; those skilled in the art can adjust it according to requirements, such as 63mm. 2 ~404mm 2 Choose from the range.

[0077] In one specific embodiment of this application, the battery cell output terminal 410 includes a tab, which is directly welded to the terminal post 200. The range of Xmm is 12mm to 35mm. For example, in this embodiment, Xmm can be 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm, 35mm, etc. This embodiment does not limit the specific value of Xmm; those skilled in the art can select it within the range of 12mm to 35mm according to their needs.

[0078] In this embodiment, the tab is directly welded to the terminal post 200 without using other intermediate adapters, which makes the current transmission path from the cell 400 to the terminal post 200 shorter and the area of ​​the first solder mark 510 smaller. At this time, the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520 is selected within a larger range, reducing the impact of the heat generated at the first solder mark 510 on the second solder mark 520 and ensuring the welding strength between the battery cover plate 120 and the housing body 110.

[0079] In one specific embodiment of this application, the cell output terminal 410 includes a tab and an adapter piece. The adapter piece is soldered to the tab to form a third solder mark, and the adapter piece is soldered to the terminal post 200 to form a first solder mark 510. In other words, the tab is soldered to the terminal post 200 via the adapter piece. The adapter piece provides a larger current conduction cross-sectional area, which can reduce the connection resistance from the tab to the terminal post 200, thereby reducing energy loss and heat generation. In addition, since there may be slight deviations in the position of the tab, the adapter piece provides adjustment space, facilitating alignment with the fixed-position terminal post 200, improving assembly compatibility and production yield.

[0080] In this embodiment, the heat transfer distance between the first solder mark 510 and the third solder mark is ≤65mm. It should be noted that the heat transfer distance between the first solder mark 510 and the third solder mark refers to the projected distance between the first solder mark 510 and the third solder mark on the target plane, which is a plane parallel to the large surface of the adapter piece. A heat transfer distance between the first solder mark 510 and the third solder mark ≤65mm can reduce the current path length from the tab to the electrode post 200 and increase the current transmission rate.

[0081] The method for measuring the heat transfer distance between the first solder mark 510 and the third solder mark is as follows: unfold the adapter plate into a plane and use a vernier caliper to measure the minimum distance between the first solder mark and the third solder mark on the adapter plate.

[0082] In one specific embodiment of this application, the battery cell output terminal 410 includes a tab and an adapter piece. The adapter piece is welded to the tab to form a third solder mark, and the adapter piece is welded to the terminal post 200 to form a first solder mark 510. The area of ​​the third solder mark and the area of ​​the first solder mark 510 both refer to their projected areas on the target plane.

[0083] The area of ​​the third solder mark is larger than that of the first solder mark 510. In other words, the area of ​​the welding region between the tab and the adapter is larger than the area of ​​the welding region between the terminal 200 and the adapter. Tabs are generally multi-layered, thus increasing the area of ​​the welding region between the tab and the adapter to ensure effective current flow. While ensuring the current flow capacity from cell 400 to terminal 200, increasing the area of ​​the third solder mark and reducing the area of ​​the first solder mark 510 increases the minimum heat transfer path from the first solder mark 510 to the second solder mark 520, thereby preventing the rapid transfer of heat from the first solder mark 510 to the welding wires of the battery cover 120 and the casing body 110, which could lead to welding wire cracking. Furthermore, increasing the area of ​​the third solder mark also reduces the overcurrent resistance, thereby reducing heat generation and the heat transferred from the first solder mark 510 to the welding wires of the battery cover 120 and the casing body 110, reducing the risk of welding wire cracking.

[0084] In one specific embodiment of this application, the thickness of the terminal post 200 is greater than the thickness of the battery cover 120 along the direction perpendicular to the large surface of the battery cover 120. This arrangement... This can increase the heat transfer path on the electrode post 200, thereby increasing the minimum heat transfer path length from the first solder mark 510 to the second solder mark 520, preventing the heat at the first solder mark 510 from being quickly transferred to the welding wires of the battery cover plate 120 and the housing body 110, which could lead to the problem of the welding wires cracking.

[0085] The thickness of the electrode post 200 can range from 3mm to 8mm. For example, in this embodiment, the thickness of the electrode post 200 can be 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, etc. This embodiment does not limit the specific value of the thickness of the electrode post 200; those skilled in the art can select a value within the range of 3mm to 8mm according to their needs.

[0086] The thickness of the battery cover 120 ranges from 0.8mm to 3mm. For example, in this embodiment, the thickness of the battery cover 120 can be 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3.0mm, etc. This embodiment does not limit the specific value of the thickness of the battery cover 120; those skilled in the art can select a value within the range of 0.8mm to 3mm according to their needs.

[0087] The difference between the thickness of the terminal post 200 and the thickness of the battery cover 120 (i.e., the thickness of the terminal post 200 minus the thickness of the battery cover 120) is 0.5mm to 5mm. For example, in this embodiment, the difference can be 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.2mm, 4.5mm, 4.8mm, 5.0mm, etc. This embodiment does not limit the specific value of the difference; those skilled in the art can select a value within the range of 0.5mm to 5mm according to their needs.

[0088] Preferably, the difference between the thickness of the terminal post 200 and the thickness of the battery cover 120 is 1mm to 3mm.

[0089] This design increases the surface area of ​​the terminal post 200, preventing the terminal post 200 from being in complete circumferential contact with the battery cover plate 120, which would cause the heat from the terminal post 200 to be rapidly transferred to the second solder mark 520, causing the second solder mark 520 to crack. At the same time, it prevents the terminal post 200 from being too thick, which would increase the heat generated by the terminal post 200, affecting the second solder mark 520 and causing it to crack.

[0090] Furthermore, such as Figure 3As shown, when the thickness of the terminal post 200 is greater than the thickness of the battery cover plate 120, along the direction perpendicular to the large surface of the battery cover plate 120, the side of the terminal post 200 away from the cell 400 can be designed to protrude from the battery cover plate 120 in a direction away from the cell 400 (when the battery cover plate 120 has a certain thickness, protruding from the battery cover plate 120 in a direction away from the cell 400 means protruding from the surface of the battery cover plate 120 away from the cell 400). With this configuration, the terminal post 200 protrudes from the outside of the battery cover plate 120, which can quickly dissipate heat to the external environment, reduce the temperature of the terminal post 200, and thus reduce the heat transferred from the terminal post 200 to the welding wires of the battery cover plate 120 and the housing body 110, ensuring the strength of the welding wires.

[0091] Specifically, the protrusion of the terminal post 200 from the battery cover 120 on the side facing away from the battery cell 400 is 2mm to 4mm. For example, in this embodiment, the protrusion size can be 2mm, 2.2mm, 2.4mm, 2.6mm, 2.8mm, 3mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, 3.9mm, 4mm, etc. This embodiment does not limit the specific value of the protrusion size; those skilled in the art can select a value within the range of 2mm to 4mm according to their needs.

[0092] When the thickness of the terminal post 200 is greater than the thickness of the battery cover plate 120, along the direction perpendicular to the large surface of the battery cover plate 120, the side of the terminal post 200 closest to the cell 400 can be designed to protrude from the battery cover plate 120 in a direction closer to the cell 400 (when the battery cover plate 120 has a certain thickness, protruding from the battery cover plate 120 in a direction closer to the cell 400 means protruding from the surface of the battery cover plate 120 closest to the cell 400). With this configuration, the terminal post 200 protrudes from the inner side of the battery cover plate 120, ensuring that the minimum heat transfer path from the first solder mark 510 to the second solder mark 520 includes at least the thickness of the terminal post 200 protruding from the inner side of the battery cover plate 120. This increases the minimum heat transfer path from the first solder mark 510 to the second solder mark 520, preventing the heat at the first solder mark 510 from being rapidly transferred to the welding lines of the battery cover plate 120 and the housing body 110, thus avoiding the problem of welding line cracking.

[0093] When the thickness of the terminal post 200 is greater than the thickness of the battery cover plate 120, it can also be designed such that, along the direction perpendicular to the large surface of the battery cover plate 120, the side of the terminal post 200 away from the cell 400 protrudes from the battery cover plate 120 in a direction away from the cell 400, while the side of the terminal post 200 closer to the cell 400 protrudes from the battery cover plate 120 in a direction closer to the cell 400. This arrangement can achieve the technical effects of both embodiments described above, and will not be elaborated further here.

[0094] Furthermore, along the direction perpendicular to the large surface of the battery cover 120, the first dimension is the size by which the terminal post 200 protrudes from the battery cover 120 in the direction away from the battery cell 400 (when the battery cover 120 has a certain thickness, protruding from the battery cover 120 in the direction away from the battery cell 400 means protruding from the surface of the battery cover 120 away from the battery cell 400). The second dimension is the size by which the terminal post 200 protrudes from the battery cover 120 in the direction close to the battery cell 400 (when the battery cover 120 has a certain thickness, protruding from the battery cover 120 in the direction close to the battery cell 400 means protruding from the surface of the battery cover 120 close to the battery cell 400).

[0095] In this embodiment, the first dimension is larger than the second dimension. In other words, the electrode post 200 protrudes more from the battery cover plate 120 in the direction away from the cell 400, so as to reduce the space occupied inside the battery, while increasing the contact area between the electrode post 200 and the external space, improving the heat dissipation effect of the electrode post 200, and reducing the temperature of the electrode post 200.

[0096] In a specific embodiment of this application, the terminal post 200 includes a first terminal post and a second terminal post, one of which is a positive terminal post and the other is a negative terminal post. Both the positive and negative terminal posts are located on the battery cover plate 120. The minimum distance between the first solder mark 510 of the positive terminal post and the first solder mark 510 of the negative terminal post is 50mm to 280mm. For example, in this embodiment, the minimum distance between the first solder mark 510 of the positive terminal post and the first solder mark 510 of the negative terminal post can be 50mm, 70mm, 90mm, 110mm, 130mm, 150mm, 170mm, 190mm, 210mm, 230mm, 250mm, 280mm, etc. This embodiment does not limit the specific value of the minimum distance between the first solder mark 510 of the positive terminal post and the first solder mark 510 of the negative terminal post; those skilled in the art can select a value within the range of 50mm to 280mm according to their needs.

[0097] This design avoids the heat from the two heat sources accumulating due to the close proximity of the positive and negative terminals, which could adversely affect the bonding strength between the battery cover 120 and the main body 110.

[0098] In one specific embodiment of this application, an explosion-proof valve 300 is provided on the battery cover 120. The explosion-proof valve 300 refers to an element or component that can be actuated to release the internal pressure or temperature when the internal pressure or temperature of the battery reaches a predetermined threshold.

[0099] During battery use, the explosion-proof valve 300 is mainly used to allow gas inside the battery to escape in order to reduce the internal pressure of the battery in order to prevent the battery from deforming or exploding due to excessive increase in internal pressure when the battery experiences thermal runaway or other situations.

[0100] The explosion-proof valve 300 is made of any material, including but not limited to aluminum, steel, alloys, etc. The shape of the explosion-proof valve 300 is not limited, such as square, oblong, elliptical, racetrack-shaped, etc. The type of explosion-proof valve 300 is not limited, such as a scored explosion-proof valve, where the scored areas include grooves, which can be formed by stamping or laser etching.

[0101] The explosion-proof valve 300 can be formed directly on the battery cover 120 or connected to it. If the explosion-proof valve 300 is connected to the battery cover 120, a pressure relief port needs to be provided on the battery cover 120, and the explosion-proof valve 300 is connected to the pressure relief port to seal it. The connection method can be welding or other connection methods. When the explosion-proof valve 300 is formed directly on the battery cover 120, it can be obtained by thinning the battery cover 120.

[0102] In this embodiment, by providing an explosion-proof valve 300 on the battery cover 120, if the battery cover 120 is a battery cover 120, when the internal pressure of the battery increases, causing the weld line between the battery cover 120 and the housing body 110 to be at risk of cracking, the explosion-proof valve 300 will preferentially burst open to release pressure, so as to avoid the weld line between the battery cover 120 and the housing body 110 cracking and causing more serious thermal runaway.

[0103] The explosion-proof valve 300 may include a weak portion 310, the area enclosed by the weak portion 310 forming a weak zone. The weak zone is configured such that when the internal pressure of the housing 100 reaches the pressure relief level, the weak portion 310 breaks, causing the weak zone to open and release pressure. The weak portion 310 may have a groove or other structure. When the internal pressure of the housing 100 reaches the pressure relief level, the groove or other structure breaks, causing the weak zone to open and release pressure. When a large amount of gas is generated inside the battery due to abnormal conditions such as overcharging, overheating, or short circuit, causing the internal pressure to rise to a certain level, the pressure generated by the gas will cause the groove or other structure to break, causing the weak zone to detach or bend on the housing 100, thus forming a pressure relief port on the housing 100 to relieve the pressure inside the housing 100.

[0104] like Figure 7 , Figure 8 and Figure 9 As shown, the weak section 310 can have a waist-shaped structure, that is, it includes a straight segment 311 and a curved segment 312. The weak section 310 can adopt... Figure 8The diagram shows the arrangement of the straight segment 311 opposite to the long side of the battery cover 120. It should be noted that the portion of the weak part 310 opposite to the long side of the battery cover 120 refers to the part of the weak part 310 that is closer to the long side of the battery cover 120. This straight segment 311 can extend in a straight line, and its extension direction can be parallel to the long side of the battery cover 120, or it can be at a certain angle. In this embodiment, arranging the straight segment 311 of the weak part 310 opposite to the long side of the battery cover 120 can increase the opening area of ​​the explosion-proof valve 300 and ensure the pressure relief rate.

[0105] The weak point 310 can also be used Figure 9 The diagram shows the arrangement of the straight segment 311 opposite to the short side of the battery cover 120. It should be noted that the portion of the weak section 310 opposite to the short side of the battery cover 120 refers to the portion of the weak section 310 that is closest to the short side of the battery cover 120. The midpoint of the curved segment 312 of the weak section 310 can be the point closest to the long side of the battery cover 120; alternatively, other points on the curved segment 312 can also be designed to be the points closest to the long side of the battery cover 120.

[0106] The minimum distance between the explosion-proof valve 300 and the first solder mark 510 ranges from 30mm to 110mm. It should be noted that the minimum distance between the explosion-proof valve 300 and the first solder mark 510 refers to the projected distance between them on a reference plane, which is a plane parallel to the battery cover 120. For example, in this embodiment, the minimum distance between the explosion-proof valve 300 and the first solder mark 510 can be 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 102mm, 104mm, 107mm, 110mm, etc. This embodiment does not limit the specific value of the minimum distance between the explosion-proof valve 300 and the first solder mark 510; those skilled in the art can select a value within the range of 30mm to 110mm according to their needs.

[0107] In this embodiment, the minimum distance between the explosion-proof valve 300 and the first solder mark 510 is selected within the range of 30mm to 110mm. This avoids the problem that if the distance is too small, the heat from the first solder mark 510 will be quickly conducted to the explosion-proof valve 300, causing the explosion-proof valve 300 to open prematurely. It also avoids the problem that if the distance is too large, the pole post 200 and the explosion-proof valve 300 will occupy too much area of ​​the battery cover plate 120.

[0108] Furthermore, such as Figure 10As shown, the weak portion 310 includes a groove 301. The opening of the groove 301 can be arranged facing the battery cell 400 or away from the battery cell 400. The groove 301 can also be provided on both the side facing the battery cell 400 and the side away from the battery cell 400. In this embodiment, the thickness of the bottom wall of the groove 301 ranges from 0.04mm to 0.3mm. For example, in this embodiment, the thickness of the bottom wall of the groove 301 can be 0.04mm, 0.06mm, 0.08mm, 0.10mm, 0.12mm, 0.14mm, 0.16mm, 0.18mm, 0.20mm, 0.22mm, 0.25mm, 0.30mm, etc. This embodiment does not limit the specific value of the bottom wall thickness of the groove 301; those skilled in the art can select a value within the range of 0.04mm to 0.3mm according to their needs.

[0109] This design avoids the problem that the groove 301 of the weak part 310 is too shallow due to the excessive thickness of the bottom wall of the groove 301, which would prevent the weak part 310 from breaking and releasing pressure in time; it also avoids the problem that the groove 301 of the weak part 310 is too deep due to the insufficient thickness of the bottom wall of the groove 301, which would cause premature pressure release before reaching the pressure release threshold.

[0110] In a specific embodiment of this application, the terminal 200 is the first terminal, and the battery also includes a second terminal. One of the first and second terminals is the positive terminal, and the other is the negative terminal. The first terminal is located on the battery cover 120, and the second terminal and the first terminal are respectively disposed on two opposite surfaces of the housing 100, that is, the second terminal is arranged on the opposite wall surface of the battery cover 120. Since the first and second terminals are distributed on opposite wall surfaces, the two first solder marks 510 are relatively dispersed, and the heat conducted to the second solder mark 520 is small. Based on this, in this embodiment, the Y / X range is 8~123.8, that is, Y / X is selected in a larger range, which can increase the volumetric energy density of the battery, reduce the minimum heat transfer path from the first solder mark 510 to the second solder mark 520, thereby increasing the solder area of ​​the first solder mark 510 and improving the current carrying capacity.

[0111] For example, in this embodiment, Y / X can be 8, 15, 28, 35, 45, 50, 56, 68, 78, 88, 98, 100, 108, 118, 123.8, etc. This embodiment does not limit the specific value of Y / X, and those skilled in the art can select it within the range of 8 to 123.8 according to their needs.

[0112] In one specific embodiment of this application, the penetration depth of the second solder mark 520 ranges from 0.3mm to 2.0mm. Exemplarily, in this embodiment, the penetration depth of the second solder mark 520 can be 0.3mm, 0.5mm, 0.7mm, 0.9mm, 1.1mm, 1.3mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, etc. This embodiment does not limit the specific value of the penetration depth of the second solder mark 520; those skilled in the art can select it within the range of 0.3mm to 2.0mm according to their needs.

[0113] This design avoids the problem that the weld joint is not fully penetrated due to the insufficient penetration of the second weld mark 520, which would become a stress concentration point and crack source, resulting in poor load-bearing capacity. It also avoids the problem that the heat input is too high due to the excessive penetration of the second weld mark 520, which would cause the casing body 110 and battery cover plate 120 to twist or burn through.

[0114] The penetration direction of the second weld 520 can be set perpendicular to the large surface of the battery cover 120. Setting the penetration direction in this way facilitates welding and improves welding efficiency. Alternatively, the penetration direction of the second weld 520 can be set parallel to the large surface of the battery cover 120. Setting the penetration direction in this way can improve the strength of the second weld between the battery cover 120 and the housing body 110 and prevent cracking.

[0115] The penetration depth test method for the second solder mark 520 is as follows: The sample is placed in a mold, filled with a mixture of epoxy resin and curing agent, and cured at room temperature. The sample is then cut along the vertical plane of the second solder mark 520, and subjected to grinding and etching. The width and depth of the second solder mark 520 are observed and measured using an electron microscope. The etching solution can be selected according to the material of the second solder mark 520.

[0116] When the material of the second weld mark 520 includes steel, a 4% nitric acid alcohol solution (4% nitric acid + 96% anhydrous ethanol) is commonly used as the etching solution.

[0117] When the material of the second solder mark 520 includes aluminum alloy, Keller's reagent (with the following ratio: 1%HF + 1.5%HCl + 2.5%HNO3 + 95%H2O) is usually used as the etching solution.

[0118] The weld width of the second solder mark 520 ranges from 0.6mm to 3mm. For example, in this embodiment, the weld width of the second solder mark 520 can be 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.4mm, 2.7mm, 3.0mm, etc. This embodiment does not limit the specific value of the weld width of the second solder mark 520; those skilled in the art can select a value within the range of 0.6mm to 3mm according to their needs.

[0119] This design avoids the problems of the second weld mark 520 being prone to undercut and slag inclusion due to its small weld width, which also makes it difficult for gas to escape, increases the risk of porosity, and makes it less susceptible to impurities floating and crystallization cracks. It also avoids the problems of the second weld mark 520 being too wide, which would cause severe deformation of the shell body 110 and battery cover plate 120, coarse grains in the heat-affected zone, and performance degradation.

[0120] In one specific embodiment of this application, the aspect ratio of the battery cover 120 ranges from 5 to 15. The larger surface of the battery cover 120 has a rectangular structure. The aspect ratio of the battery cover 120 refers to the ratio of the length of the longer side to the width of the larger surface of the battery cover 120. For example, in this embodiment, the aspect ratio of the battery cover 120 can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, etc. This embodiment does not limit the aspect ratio of the battery cover 120; those skilled in the art can select one within the range of 5 to 15 according to their needs.

[0121] In this embodiment, selecting the aspect ratio of the battery cover 120 within the range of 5 to 15 allows for the arrangement of more batteries within the battery pack. The YWh / L range is 200Wh / L to 700Wh / L. For example, YWh / L can be 200Wh / L, 300Wh / L, 400Wh / L, 500Wh / L, 600Wh / L, 650Wh / L, 660Wh / L, 670Wh / L, 680Wh / L, 690Wh / L, 700Wh / L, etc. This embodiment does not limit the specific value of YWh / L; those skilled in the art can select it within the range of 200Wh / L to 700Wh / L according to their needs.

[0122] In this embodiment, the volumetric energy density of the battery is selected within a small range to avoid the problem that the large surface of the battery is prone to bulging during charging and discharging due to excessive volumetric energy density, which could lead to cracking of the long side weld line between the battery cover plate 120 and the housing body 110.

[0123] like Figure 3As shown in a specific embodiment of this application, an insulating member 600 is provided between the terminal 200 and the battery cover 120. The terminal 200 and the battery cover 120 are kept insulated by the insulating member 600, blocking the current path between the terminal 200 and the battery cover 120 and preventing short circuits inside the battery. Furthermore, the insulating member 600 also prevents electrolyte leakage. The liquid electrolyte inside the battery is corrosive and may be flammable. The insulating member 600 ensures that the electrolyte will not seep out from the tiny gaps between the terminal 200 and the battery cover 120. Leakage can lead to battery failure and may corrode external circuits or cause safety problems.

[0124] In this embodiment, the thickness of the insulating component 600 is 0.1mm to 5mm, meaning the thickness of the insulating component 600 at any location falls within the range of 0.1mm to 5mm. For example, in this embodiment, the thickness of the insulating component 600 can be 0.1mm, 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.2mm, 4.5mm, 5.0mm, etc. This embodiment does not limit the thickness of the insulating component 600; those skilled in the art can select a thickness within the range of 0.1mm to 5mm according to their needs.

[0125] This design reduces the rate at which heat is transferred from the terminal post 200 to the battery cover 120, preventing the heat at the connection point between the terminal post 200 and the cell output end (i.e., the heat at the first solder mark 510) from being quickly transferred to the welding line between the battery cover 120 and the housing body 110 (i.e., the second solder mark 520), which could lead to the welding line between the battery cover 120 and the housing body 110 cracking easily.

[0126] The insulating member 600 includes an upper insulating member 610 and / or a lower insulating member 620. The upper insulating member 610 is disposed between the terminal post 200 and the side of the battery cover plate 120 away from the cell 400, so that the upper side of the terminal post 200 and the battery cover plate 120 are insulated from each other. The lower insulating member 620 is disposed between the lower side of the terminal post 200 and the battery cover plate 120 (the side closer to the cell 400), and is used to insulate the lower side of the terminal post 200 and the battery cover plate 120 from each other, and to insulate the cell 400 and the battery cover plate 120 from each other, so as to reduce the risk of short circuit.

[0127] The insulating component 600 may be made of plastic, rubber, or other insulating materials. Plastics may include polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), and polyvinyl chloride (PVC). Rubber may include fluororubber, nitrile rubber, or heteropolymer rubber.

[0128] When the insulating component 600 is located between the battery cover 120 on the side away from the battery cell and the terminal post 200 (i.e., the insulating component 600 is the upper insulating component 610), the thickness of the insulating component 600 is 0.1mm to 0.5mm. For example, in this embodiment, the thickness of the insulating component 600 can be 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.42mm, 0.44mm, 0.46mm, 0.48mm, 0.5mm, etc. This embodiment does not limit the thickness of the insulating component 600; those skilled in the art can select a thickness within the range of 0.1mm to 5mm according to their needs.

[0129] When the insulating component 600 is located between the battery cover 120 and the terminal post 200 near the cell side (i.e., the lower insulating component 620), the thickness of the insulating component 600 is 0.5mm to 5mm. For example, in this embodiment, the thickness of the insulating component 600 can be 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.2mm, 4.5mm, 5.0mm, etc. This embodiment does not limit the thickness of the insulating component 600; those skilled in the art can select a thickness within the range of 0.5mm to 5mm according to their needs.

[0130] This design prevents the heat inside the battery from being rapidly transferred to the second solder mark 520, which could cause the second solder mark 520 to crack.

[0131] In one specific embodiment of this application, the battery cell 400 includes a positive electrode sheet, which includes a positive electrode material. The positive electrode material includes a layered transition metal oxide, which generates a high amount of heat during charging and discharging, easily causing large-area swelling of the battery. Based on this, the range of YWh / L is 300Wh / L to 1000Wh / L. For example, YWh / L can be 300Wh / L, 400Wh / L, 500Wh / L, 600Wh / L, 700Wh / L, 800Wh / L, 900Wh / L, 1000Wh / L, etc. This embodiment does not limit the specific value of YWh / L; those skilled in the art can select within the range of 300Wh / L to 1000Wh / L according to their needs.

[0132] Layered transition metal oxides include nickel-cobalt-manganese ternary materials and / or nickel-cobalt-aluminum ternary materials, wherein the nickel-cobalt-manganese ternary materials 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.

[0133] In this embodiment, the volumetric energy density of the battery is selected within a small range to reduce the heat generated by the battery and lower the probability of cracking of the weld lines between the battery cover plate 120 and the housing body 110.

[0134] In one specific embodiment of this application, when the battery is charged from 10% SOC to 80% SOC in less than 20 minutes, i.e., when the battery is a fast-charging battery, the Y / X range is 9 to 123.8. For example, in this embodiment, Y / X can be 9, 15, 28, 35, 45, 50, 56, 68, 78, 88, 98, 100, 108, 118, 123.8, etc. This embodiment does not limit the specific value of Y / X; those skilled in the art can select a value within the range of 9 to 123.8 according to their needs.

[0135] That is, Y / X is selected within a larger range to improve the volumetric energy density of the battery, reduce the minimum heat transfer path from the first solder mark 510 to the second solder mark 520, thereby expanding the solder area of ​​the first solder mark 510 and improving the overcurrent capability to match the fast charging capability of the battery.

[0136] Furthermore, when the battery is charged from 10% SOC to 80% SOC in less than 20 minutes, the maximum temperature of the terminal 200 is less than or equal to 90°C.

[0137] This design can prevent the temperature of the terminal post 200 from getting too high, which would cause excessive heat at the first solder mark 510 to be transferred to the solder line between the battery cover plate 120 and the housing body 110, thus preventing the solder line from cracking.

[0138] The specific battery charging strategy can be as follows: Place the prepared battery at 25°C for 4 hours until thermal equilibrium is reached. Charge the battery at a constant current of 0.1C to the upper limit voltage, then charge at a constant voltage until the current is less than or equal to 0.05C; then discharge at 0.1C to the lower limit voltage, repeating the above steps 3 times, and taking the capacity discharged in the third cycle as the battery discharge capacity; let it stand for 10 minutes, then discharge at 1C to 2.5V, let it stand for 10 minutes, then charge at 0.33C to 10% SOC; then first charge at a constant current of 4C, then gradually reduce the charging rate in 0.2C increments until it drops to 0.4C, with the cutoff condition for each charge being charging to the upper limit voltage; when the positive electrode active material includes lithium iron phosphate, the upper limit voltage is 3.65V, and when the positive electrode active material includes lithium nickel cobalt manganese oxide, the upper limit voltage is 4.25V.

[0139] like Figure 11As shown in the embodiments, this application also discloses a battery pack, which includes at least two batteries 000, the batteries 000 being those disclosed in the above embodiments. The housing body 110 includes a first surface and a second surface, the area of ​​the first surface being larger than the area of ​​the second surface, and the at least two batteries 000 are arranged in a direction perpendicular to the first surface. That is, the arrangement of the at least two batteries 000 in the battery pack is such that the first surfaces of the batteries 000 with larger areas are arranged adjacent to each other. This arrangement can avoid excessive expansion of the first surfaces of the batteries 000 with larger areas, thereby reducing the risk of cracking of the long side solder lines of the second solder mark 520.

[0140] The battery pack disclosed in this application has the aforementioned battery 000, and therefore possesses all the technical effects of the aforementioned battery 000, which will not be repeated here.

[0141] This application also discloses an electrical device, which includes the battery pack disclosed in the above embodiments. It should be noted that this electrical device can be an electric vehicle, an electric ship, an aircraft, an energy storage device, etc. The electrical device disclosed in this application, having the aforementioned battery pack, possesses all the technical effects of the aforementioned battery pack, and will not be elaborated upon further here.

[0142] In addition, the battery pack can be placed inside the battery box, which is usually a closed or semi-closed structure made of materials such as metal and plastic. It is the physical carrier of the battery pack, and its design and manufacturing must meet the safety, reliability and functionality requirements of the battery pack in different usage scenarios.

[0143] The battery enclosure provides installation space for battery packs, BMS (Battery Management System), cooling systems, electrical connection components, etc., and through reasonable structural design, it fixes these components in the battery enclosure to ensure that they maintain a relatively stable position during operation and avoid damage to components or loosening of connections due to vibration, impact or other factors.

[0144] The battery casing can be cast from materials such as steel plates and aluminum alloys, or lightweight materials such as glass fiber reinforced composite materials and carbon fiber reinforced composite materials. The shape of the battery casing can be cylindrical, cuboid, cube, etc.

[0145] The battery enclosure may include a battery compartment and an electrical compartment. The core function of the battery compartment is to provide installation space for the battery packs, while the electrical compartment is where the various battery packs within the battery compartment are connected in series and parallel. Through the connection and arrangement of busbars within the electrical compartment, different battery packs can be connected according to design requirements to form a circuit system that meets the vehicle's power needs, while also controlling and managing the battery charging and discharging process.

[0146] The test method for the minimum heat transfer path length X mm from the first solder mark to the second solder mark is as follows: The distance between the first weld mark on the terminal post of the battery cover and the second weld mark between the battery cover and the main body of the casing was measured using computed tomography (CT). The measurements were taken along the length and width of the battery cover. The minimum distance between the first and second weld marks in both directions was measured and recorded as X mm.

[0147] The method for adjusting the minimum heat transfer path length X mm from the first solder mark to the second solder mark is as follows: The area of ​​the first solder mark can be adjusted (the area of ​​the first solder mark is within 5mm). 2 ~215mm 2 As the area of ​​the first solder mark increases, the value of Xmm decreases; as the area of ​​the first solder mark decreases, the value of Xmm increases. Alternatively, the distance between the pole and the surface of the battery cover facing the cell can be adjusted (protrusion size 2mm ~ 4mm). The greater the protrusion distance, the greater the value of Xmm; the smaller the protrusion distance, the smaller the value of Xmm.

[0148] The test method for the volumetric energy density YWh / L of a battery is as follows: Under 25℃ conditions, charge the battery at 0.33C to the upper limit voltage, let it stand for 20 minutes, and then discharge it at 0.33C to the lower limit voltage. Repeat this charge-discharge cycle 3 times. Record the discharge capacity of the third cycle as the actual capacity C1 of the battery. Use vernier calipers to measure the maximum height H (including the height of the terminals), the maximum width D, and the maximum length M of the battery, in mm. According to the formula V=H×D×M, the unit of V is L. According to the formula, the volumetric energy density of the battery = (N×C1) / V, where N is the average operating voltage of the battery.

[0149] If the cathode material is a ternary material (lithium nickel cobalt manganese oxide), the upper limit voltage is 4.25V, the lower limit voltage is 2.5V, and the average operating voltage is 3.7V. If the cathode material is lithium iron phosphate, the upper limit voltage is 3.65V, the lower limit voltage is 2.5V, and the average operating voltage is 3.3V.

[0150] The method for adjusting the volumetric energy density YWh / L of a battery is as follows: The volumetric energy density of a battery can be adjusted by regulating the compaction density of the positive electrode (compaction density range 2.4 g / cm³). 3 ~3.8g / cm 3 When the cathode material is lithium nickel cobalt manganese oxide, the compaction density ranges from 2.4 g / cm³. 3 ~3.8g / cm 3 When the cathode material is lithium iron phosphate, the compaction density ranges from 2.4 g / cm³. 3~2.78g / cm 3 The higher the compaction density of the positive electrode, the higher the volumetric energy density of the battery; the lower the compaction density of the positive electrode, the lower the volumetric energy density of the battery. This can also be adjusted by changing the thickness of the separator (4μm~16μm), the thickness of the positive electrode current collector (6μm~18μm), or the thickness of the negative electrode current collector. The smaller the separator thickness or the thickness of the positive electrode current collector (4μm~12μm) or the thickness of the negative electrode current collector, the higher the volumetric energy density of the battery. Conversely, the larger the separator thickness or the thickness of the positive electrode current collector or the thickness of the negative electrode current collector, the lower the volumetric energy density of the battery.

[0151] This application also discloses a method for preparing a battery, the specific method of which is as follows.

[0152] (1) Preparation of the positive electrode: The positive electrode active material, conductive agent (e.g., acetylene black), and binder (e.g., PVDF, polyvinylidene fluoride) 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 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.

[0153] Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98): (4~1): (4~1).

[0154] (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.

[0155] Specifically, the ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0156] (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.

[0157] (4) Preparation of the diaphragm: Polyethylene film is selected as the diaphragm.

[0158] (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 within the battery casing, which is a square shell. The cell output terminal is welded to the terminal post of the battery cover to form the first weld mark, and the battery cover is welded to the casing to form the second weld mark. The battery is then dried, injected with electrolyte, and subsequently packaged, allowed to stand, formed, and volume-adjusted to obtain a lithium-ion battery.

[0159] 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.).

[0160] 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.).

[0161] This application discloses two performance testing methods, namely performance test 1 and performance test 2. Performance test 1 is a second solder crack test, and performance test 2 is a battery internal resistance test. The specific test procedures for performance test 1 and performance test 2 are as follows.

[0162] Performance Test 1: Second solder crack test.

[0163] Following the battery preparation method described above, 50 batteries were prepared for each embodiment and comparative example. The X value (minimum heat transfer path length from the first solder mark to the second solder mark) and Y value (volume energy density of the battery) in the batteries of each embodiment and comparative example are shown in Table 1 below. Apart from this, the remaining structures are identical. The batteries were left to stand at 25°C for 1 hour, then charged at 0.33C to the upper limit voltage at 25°C, left to stand for 20 minutes, and then discharged at 0.33C to the lower limit voltage, left to stand for 20 minutes. This cycle was repeated 3 times. The discharge capacity of the 3rd cycle was recorded as the actual capacity C1 of the battery. The batteries after being brought to capacity were then subjected to a cycle test under the following conditions: Under conditions of 25°C, charge the battery to the upper limit voltage at a charging rate of 3 times the actual capacity (1C1), let it stand for 20 minutes, then discharge it to the lower limit voltage at a discharging rate of 3 times the actual capacity (1C1), let it stand for 20 minutes, and repeat the charging and discharging strategy of charging at 3 times the actual capacity (1C1) and discharging at 3 times the actual capacity (1C1) for 500 cycles. After cycling, the batteries were charged to their upper limit voltage at a charging rate of 0.33C1 at a temperature of 25°C. The batteries of each embodiment and comparative example were subjected to end-cell puncture according to GB / T31485-2015 standard. A high-temperature resistant steel needle with a diameter of 5mm was used to pierce the battery from a direction perpendicular to the large surface of the battery at a speed of 25±5mm per second to trigger thermal runaway. After the battery thermal runaway, the weld lines between the battery casing and the cover plate were observed to see if they were cracked. If they were cracked, the number of cracked batteries was recorded as n. The weld line cracking rate was calculated as (n / 50)×100%. If the weld line cracking rate was less than or equal to 4%, it was considered good. If the weld line cracking rate was greater than 4% and less than or equal to 8%, it was considered qualified. If it was greater than 8%, it was considered unqualified.

[0164] 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.

[0165] 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 materials all meet the above test requirements. 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. The ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2. The cell style is selected as wound cell. Other cell types all meet the above test requirements.

[0166] Performance Test 2: Battery Internal Resistance Test.

[0167] Following the battery preparation method described above, three batteries were prepared for each embodiment and comparative example. The X and Y values ​​of the batteries in each embodiment and comparative example are shown in Table 1 below. Apart from this, the remaining structures are the same. The batteries were left to stand at 25°C for 1 hour, then charged at 0.33C to the upper limit voltage at 25°C, left to stand for 20 minutes, and then discharged at 0.33C to the lower limit voltage, left to stand for 20 minutes. This cycle was repeated three times. The discharge capacity of the third cycle was recorded as the actual capacity C1 of the battery. After discharging at a rate of 0.33C1 to adjust the load to 50% SOC, the batteries were left to stand for 2 hours. C1 discharges for 18 seconds. Record the initial discharge voltage as V0, the voltage V1 after the 18-second discharge ends, and the discharge current I1. Calculate the battery internal resistance = |V0-V1| / I1. Measure the internal resistance of the three batteries and take the average value. If the average internal resistance is less than 30mΩ, it is considered good. If the average internal resistance is greater than 30mΩ but less than or equal to 50mΩ, it is considered acceptable. If the average internal resistance is greater than 50mΩ, it is considered unacceptable.

[0168] Table 1 Comparison of the two performance characteristics

[0169] As can be seen from Table 1, the Y / X values ​​in Examples 1-2, 7, and 9-16 range from 5.83 to 75.00, which meets the Y / X limit of 5.83 to 123.8. After testing, it can be seen that the second solder crack test is in good condition.

[0170] In Examples 3-6 and Example 8, the value of Y / X ranges from 76.80 to 123.8, which meets the Y / X limit of 5.83 to 123.8. After testing, it can be seen that the second solder crack test is qualified.

[0171] In Examples 3-6, 8, and 10-16, the Y / X value ranges from 10.05 to 123.8, which meets the Y / X limit of 5.83 to 123.8. After testing, it can be seen that the battery internal resistance test is in good condition.

[0172] In Examples 1-2, 7, and 9, the Y / X value ranges from 5.83 to 9.51, which meets the Y / X limit of 5.83 to 123.8 and is on the smaller side of the limit. After testing, it can be seen that the battery internal resistance test is qualified.

[0173] In Examples 10-16, the value of Y / X ranges from 10.05 to 75.00, which meets the defined range of Y / X of 5.83 to 123.8. After testing, it can be seen that the second solder crack test and the battery internal resistance test are both in good condition.

[0174] In Comparative Example 3, the value of Y / X is 5.25, which does not meet the limit range of Y / X (5.83~123.8) and is lower than the lower limit of the limit range. After testing, it can be seen that although the second solder crack test is in good condition, the battery internal resistance test is unqualified.

[0175] Comparative Examples 1, 2, and 4 show Y / X values ​​of 137.53, 126.89, and 137.79, respectively. These values ​​do not meet the Y / X limit range of 5.83 to 123.8 and are higher than the upper limit of the Y / X limit range. The tests show that although the battery internal resistance test is in good condition, the second solder crack test is unqualified.

[0176] 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.

[0177] 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.

[0178] 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.

[0179] 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, The device includes a terminal post (200), a housing (100), and a battery cell (400) located inside the housing (100). The battery cell (400) includes a battery cell body and a battery cell output terminal (410). The housing (100) includes a housing body (110) with an opening at one end and a battery cover (120). The terminal post (200) is disposed on the battery cover (120) of the housing (100) and is welded to the battery cell output terminal (410) to form a first solder mark (510). The battery cover (120) is welded to the opening end of the housing body (110) to form a second solder mark (520). The minimum heat transfer path length from the first solder mark (510) to the second solder mark (520) is X mm, the volumetric energy density of the battery is Y Wh / L, and the range of Y / X is 5.83~123.

8.

2. The battery according to claim 1, characterized in that, The battery cover (120) is rectangular, and the second solder mark (520) includes a long side solder line located on the long side of the battery cover (120) and a short side solder line located on the short side of the battery cover (120). The heat transfer path length from the first solder mark (510) to the long side solder wire is the first path length, and the heat transfer path length from the first solder mark (510) to the short side solder wire is the second path length. The first path length is less than the second path length, and the range of X mm is 10 mm to 35 mm.

3. The battery according to claim 2, characterized in that, The difference between the first path length and the second path length is in the range of 10mm to 100mm.

4. The battery according to claim 1, characterized in that, The battery cover (120) is rectangular, and the second solder mark (520) includes a long side solder line located on the long side of the battery cover (120) and a short side solder line located on the short side of the battery cover (120). The heat transfer path length from the first solder mark (510) to the long side solder wire is the first path length, and the heat transfer path length from the first solder mark (510) to the short side solder wire is the second path length. The first path length is greater than the second path length.

5. The battery according to claim 1, characterized in that, The area of ​​the first solder mark (510) is the first area, and the area of ​​the electrode post (200) near the surface of the cell (400) is the second area. The ratio of the first area to the second area is in the range of 0.07 to 0.

75.

6. The battery according to claim 1, characterized in that, The battery cell output terminal (410) includes a tab, which is directly welded to the terminal post (200), and the Xmm range is 12mm~35mm.

7. The battery according to claim 1, characterized in that, The cell output terminal (410) includes a tab and an adapter plate. The adapter plate is welded to the tab to form a third solder mark, and the adapter plate is welded to the pole (200) to form a first solder mark (510). The heat transfer distance between the first solder mark (510) and the third solder mark is ≤65mm.

8. The battery according to claim 1, characterized in that, The cell output terminal (410) includes a tab and an adapter piece. The adapter piece is welded to the tab to form a third solder mark, and the adapter piece is welded to the terminal post (200) to form a first solder mark (510). The area of ​​the third solder mark is larger than the area of ​​the first solder mark (510).

9. The battery according to claim 1, characterized in that, Along the direction perpendicular to the large surface of the battery cover (120), the thickness of the terminal post (200) is greater than the thickness of the battery cover (120).

10. The battery according to claim 9, characterized in that, Along the direction perpendicular to the large surface of the battery cover (120), the pole post (200) protrudes from the battery cover (120) toward the side opposite to the battery cell (400). And / or, Along the direction perpendicular to the large surface of the battery cover (120), the pole post (200) protrudes from the battery cover (120) toward the side closer to the cell (400).

11. The battery according to claim 9, characterized in that, Along the direction perpendicular to the large surface of the battery cover (120), the dimension by which the pole post (200) protrudes from the battery cover (120) toward the side opposite to the battery cell (400) is the first dimension, and the dimension by which the pole post (200) protrudes from the battery cover (120) toward the side closer to the battery cell (400) is the second dimension. The first dimension is larger than the second dimension.

12. The battery according to any one of claims 1-11, characterized in that, The terminal post (200) includes a first terminal post and a second terminal post, both of which are located on the battery cover plate (120). The minimum distance between the first solder mark (510) of the first terminal post and the first solder mark (510) of the second terminal post is 50mm to 280mm.

13. The battery according to any one of claims 1-11, characterized in that, The battery cover (120) is provided with an explosion-proof valve (300), and the minimum distance between the explosion-proof valve (300) and the first solder mark (510) is 30mm~110mm.

14. The battery according to claim 13, characterized in that, The explosion-proof valve (300) includes a weak part (310), the weak part (310) includes a groove (301), and the thickness of the bottom wall of the groove (301) ranges from 0.04mm to 0.3mm.

15. The battery according to any one of claims 1-11, characterized in that, The terminal (200) is the first terminal, and the battery also includes a second terminal. The first terminal is located on the battery cover (120). The second terminal and the first terminal are respectively disposed on two opposite surfaces of the housing (100), and the Y / X range is 8~123.

8.

16. The battery according to any one of claims 1-11, characterized in that, The penetration depth of the second solder mark (520) ranges from 0.3 mm to 2.0 mm, and / or the penetration width of the second solder mark (520) ranges from 0.6 mm to 3 mm.

17. The battery according to any one of claims 1-11, characterized in that, The aspect ratio of the battery cover (120) is in the range of 5 to 15, and the YWh / L range is in the range of 200Wh / L to 700Wh / L.

18. The battery according to any one of claims 1-11, characterized in that, An insulating component (600) is provided between the terminal post (200) and the battery cover plate (120), and the thickness of the insulating component (600) is 0.1mm~5mm.

19. The battery according to any one of claims 1-11, characterized in that, The cell (400) includes a positive electrode sheet, the positive electrode sheet includes a positive electrode material, the positive electrode material includes a layered transition metal oxide, and the YWh / L range is 300Wh / L~1000Wh / L.

20. The battery according to any one of claims 1-11, characterized in that, When the battery is charged from 10% SOC to 80% SOC in less than 20 minutes, the Y / X range is 9 to 123.

8.

21. The battery according to claim 20, characterized in that, When the battery is charged from 10% SOC to 80% SOC in less than 20 minutes, the highest temperature of the terminal (200) is less than or equal to 90°C.

22. A battery pack, characterized in that, It includes at least two batteries, the batteries being batteries as described in any one of claims 1-21, the housing body (110) including a first surface and a second surface, the area of ​​the first surface being larger than the area of ​​the second surface, and at least two of the batteries being arranged in a direction perpendicular to the first surface.

23. An electrical appliance, characterized in that, Includes the battery pack as described in claim 22.

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