Battery cell

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell, which comprises a pole group, the shell comprises a shell body and a cover plate, the cover plate covers an opening in one side of the shell body to form a closed space for accommodating the pole group, and a liquid injection hole is formed in the cover plate; an electrode terminal provided in the case and electrically connected to the electrode group; wherein a liquid separation groove is formed in the surface, deviating from the electrode group, of the cover plate in the thickness direction, and the liquid separation groove is located between the electrode terminal and the liquid injection hole. According to the invention, the problem that the cycle performance of the battery cell is reduced due to electrode terminal corrosion caused by leaked electrolyte can be solved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to battery cells. Background Technology

[0002] Lithium-ion batteries are widely used in key fields such as transportation power systems, power storage facilities, new energy storage equipment, and aerospace and military industries due to their high energy density, stable operating voltage characteristics, good charge retention capacity, and long cycle life. The battery cell, as the basic functional unit of a lithium battery pack, mainly consists of a casing, electrolyte, and electrode assembly. The casing includes a housing that accommodates the electrode assembly and a cover plate for sealing the casing opening. The cover plate typically has injection holes for electrolyte injection and electrode terminals that are electrically connected to the electrode assembly to achieve external circuit connection.

[0003] During actual production and use, electrolyte is prone to overflow from the injection hole during the filling stage. Furthermore, as the battery's usage time increases, the injection hole seal may fail due to material aging or environmental stress, leading to electrolyte leakage. The leaked electrolyte will spread along the cover surface to the electrode terminal area, causing corrosion or the formation of non-conductive deposits on the electrode terminal surface, resulting in a decrease in the cell's cycle performance. Summary of the Invention

[0004] In view of this, the present invention provides a battery cell to solve the problem that leakage of electrolyte causes corrosion of electrode terminals, resulting in a decrease in the cycle performance of the battery cell.

[0005] In a first aspect, the present invention provides a battery cell, comprising: an electrode assembly; a housing, including a shell and a cover plate, wherein the cover plate covers an opening on one side of the shell to form a closed space for receiving the electrode assembly, and the cover plate is provided with a liquid injection hole; and electrode terminals disposed on the shell and electrically connected to the electrode assembly; wherein the cover plate is provided with a liquid-separating groove on a surface away from the electrode assembly along the thickness direction, and the liquid-separating groove is located between the electrode terminals and the liquid injection hole.

[0006] Beneficial effects: A liquid-separating groove is provided on the surface of the cover plate opposite to the electrode assembly along the thickness direction, and the liquid-separating groove is arranged between the electrode terminals and the injection hole. When a small amount of electrolyte leaks from the injection hole, the liquid-separating groove can cut off or guide the flow path of the electrolyte, preventing it from continuing to diffuse towards the electrode terminals, thus avoiding electrolyte contamination of the electrode terminals and ensuring the cycle performance and life of the battery cell.

[0007] In some embodiments, the two ends of the liquid-separating groove extend to the two edges of the cover plate along the width direction of the cover plate.

[0008] Beneficial effects: By extending the two ends of the liquid separator to the two edges of the cover plate, the liquid separator forms a continuous and complete barrier zone along the entire width of the cover plate. Electrolyte leaking from the injection hole area, regardless of its flow direction, will be intercepted by the liquid separator and will not be able to flow around the side of the liquid separator to the electrode terminals. This ensures that the leakage path of the electrolyte is completely cut off, thereby effectively protecting the electrode terminals from the erosion and contamination of the electrolyte, and thus ensuring the cycle performance and life of the battery cell.

[0009] In some embodiments, liquid-separating grooves are provided on both sides of the injection hole along the length direction of the cover plate.

[0010] Beneficial effects: When the electrolyte overflows from the injection hole, it can be effectively intercepted and collected by the liquid separators on both sides, thereby preventing the electrolyte from spreading to the electrode terminals along the length of the cover plate. This provides all-round protection for the electrode terminals, further reducing the risk of electrolyte contamination of the electrode terminals and avoiding the problems of increased electrode terminal resistance and decreased battery cycle performance caused by electrolyte corrosion. This improves the long-term stability and reliability of the battery cell.

[0011] In some embodiments, a plurality of liquid-separating grooves are provided on each side of the injection hole along the length direction of the cover plate, and the plurality of liquid-separating grooves are spaced apart along the length direction of the cover plate.

[0012] Beneficial effects: By setting multiple liquid-separating grooves along the length of the cover plate on one side of the injection hole, and distributing these grooves at intervals along the length of the cover plate, when the electrolyte leakage from the injection hole is large or the flow direction is uneven, the electrolyte is intercepted and collected step by step through these spaced-out grooves, forming a tiered blocking effect. This effectively extends the flow path of the electrolyte, reducing the risk of electrolyte reaching the electrode terminals and causing contamination. Simultaneously, the spaced distribution of the grooves allows for a wider coverage area, more effectively preventing irregular flow paths of the electrolyte on the cover plate surface, making the overall blocking effect more reliable. This further reduces the risk of electrolyte contamination of the electrode terminals, avoiding problems such as increased electrode terminal resistance and decreased battery cycle performance caused by electrolyte corrosion, thereby improving the long-term stability and reliability of the battery cell.

[0013] In some embodiments, the number of the plurality of liquid separators ranges from 2 to 5.

[0014] Beneficial effects: By limiting the number of electrolyte separators to between 2 and 5, multiple barriers can be formed near the injection hole. When electrolyte overflows from the injection hole, these appropriately numbered separators can intercept and retain the electrolyte step by step, effectively preventing it from flowing along the cover plate surface to the electrode terminals. At the same time, limiting the number of separators also avoids the problems of excessive number of separators leading to a more complex cover plate structure, increased processing difficulty, and excessive material consumption.

[0015] In some embodiments, the depth of the liquid-separating groove along the thickness direction of the cover plate is h, satisfying: 0.5mm≤h≤1mm; and / or, the width of the liquid-separating groove along the length direction of the cover plate is a, satisfying: 1mm≤a≤2mm.

[0016] Beneficial effects: Limiting the depth h to the range of 0.5mm to 1mm ensures that the liquid-blocking tank has sufficient liquid-blocking capacity, while avoiding weakening the overall strength of the cover plate due to excessive depth.

[0017] Limiting the width 'a' to the range of 1mm to 2mm ensures that the liquid separator has an appropriate liquid holding capacity, while avoiding occupying too much effective space of the cover plate, which could affect other functions or structural layout of the cover plate.

[0018] In some embodiments, the cover plate includes a boss portion and two flat plate portions located on both sides of the boss portion along the length direction of the cover plate. The electrode terminal is disposed on the flat plate portion, and the liquid injection hole and the liquid separation groove are disposed on the boss portion. Along the thickness direction of the cover plate, the top surface of the boss portion facing away from the electrode assembly is higher than the top surface of the electrode terminal facing away from the electrode assembly.

[0019] Beneficial effects: By making the top surface of the boss higher than the top surface of the electrode terminal, a height difference is created on the cover plate surface. The boss, being higher than the electrode terminal, serves as the primary stress-bearing area. When the cell is subjected to external impact or compression, the boss can preferentially withstand the external force, thus preventing direct force damage to the electrode terminal and ensuring its conductivity. Simultaneously, this boss structure also provides more storage space for the electrode assembly inside the cell, contributing to an increase in the cell's energy density.

[0020] The electrolyte filling hole and the electrolyte separator are located on the higher raised section, while the electrode terminals are located on the lower flat section. Overflowing electrolyte would easily flow towards the electrode terminal area under gravity. The electrolyte separator effectively prevents electrolyte from flowing towards the lower electrode terminals, thus avoiding electrolyte contamination and preventing problems such as increased terminal resistance and decreased battery cycle performance.

[0021] In some embodiments, along the thickness direction of the cover plate, the height difference between the top surface of the boss portion facing away from the electrode group and the top surface of the electrode terminal facing away from the electrode group is H, satisfying: 3mm≤H1≤5mm; and / or, along the thickness direction of the cover plate, the thickness of the flat plate portion is T1, and the thickness of the boss portion is T2, satisfying: 0.8≤T2 / T1≤1.1, 2mm≤T1≤2.5mm; and / or, along the length direction of the cover plate, the total length of the cover plate is L, satisfying: 150mm≤L≤300mm; and / or, along the width direction of the cover plate, the total width of the cover plate is W, satisfying: 25mm≤L≤75mm.

[0022] Beneficial effects: By limiting the height difference H1 between the top surface of the boss portion away from the electrode assembly and the top surface of the electrode terminal away from the electrode assembly to a range of 3mm to 5mm, it is ensured that the boss portion can preferentially withstand external forces and provide more storage space for the electrode assembly inside the cell, while avoiding the boss portion being too high, which would make the cover plate difficult to process, thus ensuring the molding yield.

[0023] By limiting the thickness T1 of the flat plate to between 2mm and 2.5mm, and controlling the ratio T2 / T1 of the thickness T2 of the boss to the thickness T1 of the flat plate to between 0.8 and 1.1, the overall structural strength and uniformity of the thickness distribution of the cover plate are ensured. This not only avoids stress concentration and potential sealing failure caused by uneven thickness, but also ensures that the cover plate has sufficient toughness and stability when subjected to internal pressure and external impact.

[0024] By limiting the total length L of the cover plate to 150mm to 300mm and the total width W to 25mm to 75mm, the overall geometry of the cover plate can be matched with the cell design, optimizing the utilization of the internal space of the cell, helping to improve the volumetric energy density of the cell, simplifying the manufacturing and assembly process, and improving production efficiency and product consistency.

[0025] In some embodiments, each of the plate portions is provided with a mounting hole, one end of the electrode terminal passes through the mounting hole, and the distance between two mounting holes along the length direction of the cover plate is L3; a first insulating member is provided between each electrode terminal and the cover plate, and the distance between two first insulating members along the length direction of the cover plate is L2; ​​the length of the boss portion along the length direction of the cover plate is L1; satisfying: 3mm≤(L2-L1) / 2≤10mm; and / or, 20mm≤(L3-L1) / 2≤25mm; preferably, along the length direction of the cover plate, the distance between the mounting hole and the nearest end of the cover plate is A, satisfying: 20mm≤A≤30mm.

[0026] Beneficial effects: By precisely controlling the spacing L2 between the two first insulating components along the length of the cover plate, the length L1 of the boss portion, and the spacing L3 between the two mounting holes to meet specific dimensional relationships (3mm≤(L2-L1) / 2≤10mm and / or 20mm≤(L3-L1) / 2≤25mm), an appropriate distance is maintained between the first insulating components and the boss portion. This avoids compression deformation or insulation failure that may result from excessively small spacing, while also preventing weakened insulation protection due to excessively large spacing. Simultaneously, the relative positions of the mounting holes and the boss portion are optimized, thereby ensuring the overall structural stability of the electrode terminals on the cover plate.

[0027] By limiting the distance A between the mounting hole and the end of the nearest cover plate to within the range of 20mm to 30mm, the layout of the cover plate edge area is further optimized, effectively avoiding the potential risks of reduced cover plate strength or electrolyte leakage caused by holes being too close together, thereby improving the long-term reliability and cycle performance of the battery cell.

[0028] In some embodiments, the electrode assembly includes a first electrode sheet, the first electrode sheet includes a first current collector and a first tab connected to the end of the first current collector, the first electrode sheet has n layers, the thickness of a single layer of the first current collector is c, and the total thickness of the first tab along the stacking direction of the first electrode sheet is t, satisfying: t=nc; a second insulating member is provided between the cover plate and the electrode assembly, the second insulating member is provided with a tab groove that avoids the first tab, and the height of the tab groove along the thickness direction of the cover plate is H2, satisfying: H2=(5~7)nc.

[0029] Beneficial effects: By accurately calculating the number of layers n of the first electrode and the thickness c of a single layer of the first current collector, the total thickness t of the first electrode tab is determined. Then, the height H2 of the electrode tab groove is set to 5 to 7 times the total thickness t of the first electrode tab. This ensures that the first electrode tab has a suitable space in the electrode tab groove, so that the first electrode tab will not be squeezed due to insufficient space during the assembly and operation of the battery cell, thus avoiding problems such as electrode tab deformation, increased resistance, or decreased connection reliability. It also avoids the problem of excessive space occupation and excessive gaps caused by electrode tab bending, which leads to low utilization of the internal space of the battery cell. This helps to improve the volumetric energy density of the battery. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the battery cell structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the front structure of the cover plate assembly according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the rear structure of the cover plate assembly according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the cover plate according to an embodiment of the present invention; Figure 5 This is a side view of the cover plate assembly according to an embodiment of the present invention; Figure 6 for Figure 5 A magnified schematic diagram of the local structure at point M; Figure 7 This is a top view of the cover plate assembly according to an embodiment of the present invention; Figure 8 This is a top view of the cover plate according to an embodiment of the present invention.

[0032] Explanation of reference numerals in the attached figures: 10-Outer shell; 11-Shell; 12-Cover plate; 121-Injection hole; 122-Liquid separator; 123-Boss portion; 124-Flat plate portion; 125-Mounting hole; 20 - Electrode terminal; 30 - First insulating element; 40 - Second insulating element; 41 - Pole lug groove; X - Length direction; Y - Width direction; Z - Thickness direction. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In the description of this invention, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0035] In the structure of lithium-ion battery cells, electrolyte leakage at the filling hole can lead to contamination of the electrode terminals, resulting in increased contact resistance and affecting the battery's cycle performance. Specifically, during the electrolyte filling stage and when the filling hole seals age or fail after prolonged battery use, leaked electrolyte spreads along the cover surface to the electrode terminals, causing corrosion and increasing the contact resistance between the electrode terminals and external connectors. This leads to reduced battery charge / discharge efficiency and decreased cycle life.

[0036] In response, the following will be combined with Figures 1 to 8 The following describes embodiments of the present invention.

[0037] According to an embodiment of the present invention, a battery cell is provided, including an electrode assembly, a housing 10, and electrode terminals 20. The housing 10 includes a shell 11 and a cover plate 12. The cover plate 12 covers an opening on one side of the shell 11, forming a closed space for housing the electrode assembly. The cover plate 12 is provided with a liquid injection hole 121. The electrode terminals 20 are disposed on the shell 11 and electrically connected to the electrode assembly. A liquid-separating groove 122 is provided on the surface of the cover plate 12 facing away from the electrode assembly along the thickness direction Z. The liquid-separating groove 122 is located between the electrode terminals 20 and the liquid injection hole 121.

[0038] A battery cell is the smallest functional unit of a lithium-ion battery. A battery cell can be a prismatic cell. The electrode assembly is the part of the battery cell used for electrochemical reactions to store and release electrical energy; it is composed of positive electrode plates, negative electrode plates, and a separator, stacked or wound together.

[0039] The housing 10 is used to house the electrode assembly and electrolyte, providing mechanical protection and environmental isolation. The housing 10 consists of two parts: a shell 11 and a cover plate 12. The shell 11 can be made of materials such as aluminum or steel. The cover plate 12 can be made of a metal or composite material that matches the shell 11, and is sealed to the shell 11 by welding, gluing, or pressing.

[0040] The cover plate 12 is provided with electrode terminals 20 and an electrolyte injection hole 121. The electrolyte injection hole 121 is used to inject electrolyte during the cell manufacturing process and to seal it after the electrolyte injection is completed. The electrolyte injection hole 121 can be a circular hole, which is sealed after the electrolyte injection is completed by means of steel balls, rivets or sealing plugs.

[0041] Electrode terminals 20 are disposed on the housing 11 and electrically connected to the electrode assembly, serving as an interface for connecting the battery cell to an external circuit for current input and output. Electrode terminals 20 can be made of conductive materials such as copper, aluminum, or nickel, and are fixed to the housing 11 by means of riveting or other methods, and connected to the electrode tabs of the electrode assembly.

[0042] The electrolyte separator 122 is a groove structure provided on the surface of the cover plate 12, which is used to block or guide the leaking electrolyte when electrolyte leakage occurs, and prevent it from flowing to the electrode terminal 20 area that is not intended to be contaminated.

[0043] A liquid-blocking groove 122 is provided on the surface of the cover plate 12 away from the electrode assembly along the thickness direction Z, and the liquid-blocking groove 122 is arranged between the electrode terminal 20 and the injection hole 121. When a small amount of electrolyte leaks from the injection hole 121, the liquid-blocking groove 122 can cut off or guide the flow path of the electrolyte, preventing it from continuing to diffuse towards the electrode terminal 20, avoiding electrolyte contamination of the electrode terminals, thereby ensuring the cycle performance and life of the battery cell.

[0044] In some embodiments, along the width direction Y of the cover plate 12, the two ends of the liquid-separating groove 122 extend to the two edges of the cover plate 12, respectively.

[0045] The liquid-separating tank 122 can be a continuous straight line. Alternatively, it can be a continuous curved line. This invention does not impose any particular limitation on the shape of the liquid-separating tank 122.

[0046] By extending the two ends of the liquid separator 122 to the two edges of the cover plate 12, the liquid separator 122 forms a continuous and complete barrier band in the entire width direction Y of the cover plate 12. Electrolyte leaking from the injection hole 121 area, regardless of its flow direction, will be intercepted by the liquid separator 122 and will not be able to bypass the side of the liquid separator 122 to flow to the electrode terminal 20. This ensures that the leakage path of the electrolyte is completely cut off, thereby effectively protecting the electrode terminal 20 from the erosion and contamination of the electrolyte, and thus ensuring the cycle performance and life of the battery cell.

[0047] As an example, along the length direction X of the cover plate 12, two electrode terminals 20 are provided on the cover plate 12, and the liquid injection hole 121 is located between the two electrode terminals 20. One of the two electrode terminals 20 is a positive terminal, and the other is a negative terminal.

[0048] In some embodiments, liquid-separating grooves 122 are provided on both sides of the injection hole 121 along the length direction X of the cover plate 12.

[0049] This design allows the electrolyte to be effectively intercepted and collected by the liquid separators 122 on both sides when it overflows from the injection hole 121. This prevents the electrolyte from spreading along the length X of the cover plate 12 to the electrode terminals 20, thus providing all-round protection for the electrode terminals 20. This further reduces the risk of electrolyte contamination of the electrode terminals 20 and avoids the problems of increased resistance of the electrode terminals 20 and decreased battery cycle performance caused by electrolyte corrosion, thereby improving the long-term stability and reliability of the battery cell.

[0050] In some embodiments, along the length direction X of the cover plate 12, a plurality of liquid-separating grooves 122 are provided on each side of the injection hole 121, and the plurality of liquid-separating grooves 122 are spaced apart along the length direction X of the cover plate 12.

[0051] With this configuration, one side of the injection hole 121 is no longer a single liquid-separating tank 122, but is composed of two or more independent or interconnected tanks.

[0052] This invention provides a plurality of liquid-separating grooves 122 along the length X of the cover plate 12, located on one side of the injection hole 121. These grooves 122 are spaced apart along the length X of the cover plate 12. When the electrolyte leakage from the injection hole 121 is large or the flow direction is uneven, the electrolyte is intercepted and collected step by step through these spaced-apart grooves 122, forming a step-by-step blocking effect. This effectively extends the flow path of the electrolyte and reduces the risk of the electrolyte reaching the electrode terminal 20 and causing contamination. At the same time, the spaced distribution of the liquid-separating grooves 122 results in a wider blocking area, which can more effectively prevent irregular flow paths of the electrolyte on the surface of the cover plate 12, making the overall blocking effect more reliable. This further reduces the risk of electrolyte contamination of the electrode terminal 20 and avoids the problems of increased resistance of the electrode terminal 20 and decreased battery cycle performance caused by electrolyte corrosion, thereby improving the long-term stability and reliability of the battery cell.

[0053] In some embodiments, the number of the plurality of liquid-separating tanks 122 ranges from 2 to 5. For example, there can be 2, 3, 4 or 5, etc.

[0054] It is worth noting that the number of liquid separators 122 on both sides can be the same or different.

[0055] By limiting the number of liquid-separating channels 122 to between 2 and 5, multiple barriers can be formed near the injection hole 121. When electrolyte overflows from the injection hole 121, these appropriately numbered liquid-separating channels 122 can intercept and retain the electrolyte step by step, effectively preventing it from flowing along the surface of the cover plate 12 to the electrode terminal 20. At the same time, limiting the number also avoids the problems of excessive liquid-separating channels 122 leading to a more complex cover plate 12 structure, increased processing difficulty, and excessive material consumption.

[0056] In some embodiments, the depth of the liquid-separating groove 122 along the thickness direction Z of the cover plate 12 is h, satisfying: 0.5mm≤h≤1mm. h can be any one of 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm, or a value between any two of them.

[0057] And / or, along the length direction X of the cover plate 12, the width of the liquid-separating groove 122 is a, satisfying: 1mm≤a≤2mm. a can be any one of 1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2mm, or any value between any two.

[0058] The depth h is limited to the range of 0.5 mm to 1 mm to ensure that the liquid-blocking groove 122 has sufficient liquid-blocking capacity, while avoiding weakening the overall strength of the cover plate 12 due to excessive depth.

[0059] Limiting the width a to the range of 1mm to 2mm ensures that the liquid separator 122 has an appropriate liquid holding capacity, while avoiding occupying too much effective space of the cover plate 12, which would affect other functions or structural layout of the cover plate 12.

[0060] In some embodiments, the cover plate 12 includes a boss portion 123 and two flat portions 124 located on both sides of the boss portion 123 along the length direction X of the cover plate 12. The electrode terminal 20 is disposed on the flat portion 124, and the liquid injection hole 121 and the liquid separator 122 are disposed on the boss portion 123. Along the thickness direction Z of the cover plate 12, the top surface of the boss portion 123 away from the electrode assembly is higher than the top surface of the electrode terminal 20 away from the electrode assembly.

[0061] The boss portion 123 of the cover plate 12 refers to the area on the cover plate 12 that is partially raised upwards, forming a relatively high platform. The flat portion 124 of the cover plate 12 refers to the relatively flat area on the cover plate 12 that is generally of uniform thickness, providing an interface for mounting or connecting the electrode terminals 20.

[0062] The top surface of the boss portion 123 facing away from the electrode group is the surface of the boss portion 123 facing the external environment of the cell, and the top surface of the electrode terminal 20 facing away from the electrode group refers to the surface of the electrode terminal 20 facing the external environment of the cell.

[0063] By making the top surface of the boss portion 123 higher than the top surface of the electrode terminal 20, a height difference is formed on the surface of the cover plate 12. The boss portion 123, being higher than the electrode terminal 20, can serve as the primary stress-bearing area. When the battery cell is subjected to external impact or compression, the boss portion 123 can preferentially withstand the external force, thereby preventing the electrode terminal 20 from being directly damaged and ensuring its conductivity. Simultaneously, this boss structure also provides more storage space for the electrode assembly inside the battery cell, contributing to an increase in the battery cell's energy density.

[0064] The electrolyte injection hole 121 and the electrolyte separator 122 are located on the higher boss portion 123, while the electrode terminal 20 is located on the lower flat portion 124. Overflowing electrolyte easily flows towards the electrode terminal 20 area under gravity. The electrolyte separator 122 effectively prevents electrolyte from flowing towards the lower electrode terminal 20, thus avoiding electrolyte contamination and preventing problems such as increased terminal resistance and decreased battery cycle performance.

[0065] In some embodiments, along the thickness direction Z of the cover plate 12, the height difference H between the top surface of the boss portion 123 away from the electrode group and the top surface of the electrode terminal 20 away from the electrode group satisfies: 3mm ≤ H1 ≤ 5mm. For example, H1 can be any one of 3mm, 3.5mm, 4mm, 4.5mm, 5mm, or any value between two of them.

[0066] And / or, along the thickness direction Z of the cover plate 12, the thickness of the flat plate portion 124 is T1, and the thickness of the boss portion 123 is T2, satisfying: 0.8≤T2 / T1≤1.1, 2mm≤T1≤2.5mm. T2 / T1 can be any one of 0.8, 0.9, 1, 1.1, or any value between two of them.

[0067] And / or, along the length direction X of the cover plate 12, the total length of the cover plate 12 is L, which satisfies: 150mm≤L≤300mm. L can be any one of 150mm, 180mm, 200mm, 250mm, 300mm, or any value between two of them.

[0068] And / or, along the width direction Y of the cover plate 12, the total width of the cover plate 12 is W, which satisfies: 25mm≤W≤75mm. W can be any one of 25mm, 35mm, 45mm, 50mm, 55mm, 65mm, 70mm, 75mm or any value between two of them.

[0069] By limiting the height difference H1 between the top surface of the boss portion 123 away from the electrode group and the top surface of the electrode terminal 20 away from the electrode group to a range of 3mm to 5mm, it is ensured that the boss portion 123 can preferentially withstand external forces and provide more storage space for the electrode group inside the cell, while avoiding the boss portion 123 being too high, which would make the cover plate 12 difficult to process, thus ensuring the molding yield.

[0070] By limiting the thickness T1 of the flat plate portion 124 to between 2 mm and 2.5 mm, and controlling the ratio T2 / T1 of the thickness T2 of the boss portion 123 to the thickness T1 of the flat plate portion 124 to between 0.8 and 1.1, the overall structural strength and thickness distribution uniformity of the cover plate 12 are ensured. This not only avoids stress concentration and potential sealing failure caused by uneven thickness, but also ensures that the cover plate 12 has sufficient toughness and stability when subjected to internal pressure and external impact.

[0071] By limiting the total length L of the cover plate 12 to 150mm to 300mm and the total width W to 25mm to 75mm, the overall geometry of the cover plate 12 can be matched with the cell design, optimizing the utilization of the internal space of the cell, helping to improve the volumetric energy density of the cell, simplifying the manufacturing and assembly process, and improving production efficiency and product consistency.

[0072] In some embodiments, each plate portion 124 is provided with a mounting hole 125, one end of the electrode terminal 20 passes through the mounting hole 125, and the distance between two mounting holes 125 along the length direction X of the cover plate 12 is L3; a first insulating member 30 is provided between each electrode terminal 20 and the cover plate 12, and the distance between two first insulating members 30 along the length direction X of the cover plate 12 is L2; ​​the length of the boss portion 123 along the length direction X of the cover plate 12 is L1; satisfying: 3mm≤(L2-L1) / 2≤10mm; and / or, 20mm≤(L3-L1) / 2≤25mm; preferably, the distance between the mounting hole 125 and the nearest end of the cover plate 12 along the length direction X of the cover plate 12 is A, satisfying: 20mm≤A≤30mm.

[0073] The first insulating element 30 provides electrical isolation and can take the form of an insulating gasket, insulating sleeve, insulating ring, or insulating coating. The material of the first insulating element 30 can be an insulating material with high dielectric strength and good chemical corrosion resistance, such as polypropylene (PP), polyethylene (PE), polyimide (PI), epoxy resin, or ceramic materials, to effectively prevent short circuits between the electrode terminal 20 and the cover plate 12 and resist electrolyte corrosion. The first insulating element 30 can be a plastic part.

[0074] By precisely controlling the spacing L2 between the two first insulating members 30 along the length X of the cover plate 12, the length L1 of the boss portion 123, and the spacing L3 between the two mounting holes 125, specific dimensional relationships are achieved: 3mm ≤ (L2-L1) / 2 ≤ 10mm and / or 20mm ≤ (L3-L1) / 2 ≤ 25mm. This ensures that an appropriate distance is maintained between the first insulating member 30 and the boss portion 123, avoiding both compression deformation or insulation failure due to excessively small spacing and weakened insulation protection due to excessively large spacing. Simultaneously, the relative positions of the mounting holes 125 and the boss portion 123 are also optimized, thereby ensuring the overall structural stability of the electrode terminal 20 on the cover plate 12.

[0075] Preferably, by limiting the distance A between the mounting hole 125 and the end of the nearest cover plate 12 to within the range of 20mm to 30mm, the layout of the edge area of ​​the cover plate 12 is further optimized, effectively avoiding the potential for reduced strength of the cover plate 12 or electrolyte leakage caused by the holes being too close, thereby improving the long-term reliability and cycle performance of the battery cell.

[0076] In some embodiments, the electrode assembly includes a first electrode sheet, which includes a first current collector and a first tab connected to the end of the first current collector. The first electrode sheet has n layers, and the thickness of a single layer of the first current collector is c. The total thickness of the tab along the stacking direction of the first electrode sheet is t, satisfying: t = nc. A second insulating member 40 is provided between the cover plate 12 and the electrode assembly. The second insulating member 40 is provided with a tab groove 41 that avoids the first tab. The height of the tab groove 41 along the thickness direction Z of the cover plate 12 is H2, satisfying: H2 = (5~7)nc. For example, H2 is 5 times nc, 6 times nc, 7 times nc, etc.

[0077] The number of first electrode layers, n, represents the total number of first electrode layers in the electrode group. The thickness c of a single first current collector layer refers to the thickness of a single first current collector (empty foil). Along the stacking direction of the first electrode layers, the total thickness t of the first tabs refers to the total dimension of all first tabs in the stacking direction.

[0078] The first electrode can be a positive electrode, the first current collector is a positive current collector, such as aluminum foil, and the first tab is a positive tab.

[0079] The first electrode can also be a negative electrode, the first current collector is a negative current collector, such as copper foil, and the first tab is a negative tab.

[0080] The second insulating component 40 prevents short circuits between the electrode assembly and the cover plate 12 and assists in sealing the inside of the battery cell. This second insulating component 40 is typically made of a polymer material with good insulation properties and resistance to electrolyte corrosion, such as polypropylene (PP) or polyethylene terephthalate (PET). The second insulating component 40 can be a lower plastic part.

[0081] The cover plate 12, electrode terminal 20, first insulating member 30 and second insulating member 40 mentioned above can constitute the cover plate 12 assembly.

[0082] The tab groove 41 is a groove or opening formed on the surface of the second insulator 40 near the electrode assembly to accommodate at least part of the tab. It provides necessary space for the tab, avoids unnecessary interference or compression between the tab and the insulator or cover plate 12 during cell assembly or operation, and reduces the space occupied by the tab bending in the housing 11, which helps to improve the volumetric energy density of the cell.

[0083] The total thickness t of the first tab is determined by accurately calculating the number of layers n of the first electrode and the thickness c of a single layer of the first current collector. Then, the height H2 of the tab groove 41 is set to 5 to 7 times the total thickness t of the first tab. This ensures that the tab has a suitable space in the tab groove 41, so that the tab will not be squeezed due to insufficient space during cell assembly and operation, thus avoiding problems such as tab deformation, increased resistance, or decreased connection reliability. It also avoids the problem of excessive space occupation and excessive gaps caused by tab bending, which leads to low utilization of the internal space of the cell. This helps to improve the volumetric energy density of the battery.

[0084] Table 1

[0085] As shown in Table 1, when the parameters of Examples 1-9 are within the range of the present invention, there is no deformation problem in the stamping of the cover plate 12, and the assembly yield of the cover plate 12 and the battery cell is normal. According to the simulation analysis of PACK in accordance with the national standard (GB / T 31467-2023), there is no obvious deformation of each part of the battery cell cover plate 12 after being subjected to force, and the strength meets the design requirements.

[0086] In Comparative Example 1, the gap between the boss part 123 and the upper plastic (first insulating part 30) is too small, and the cover plate 12 assembly has the problem of pressure damage and deformation of the boss.

[0087] In Comparative Example 2, the gap between the pole post hole (mounting hole 125) and the boss part 123 is too small, and the flatness of the flat plate part 124 is not easy to meet the stamping requirements, resulting in a low yield.

[0088] In Comparative Example 3, the space reserved for tab bending was insufficient, resulting in numerous issues with tab bending and tearing during the manufacturing process.

[0089] Unless otherwise stated, the values ​​of the parameters mentioned in this invention can be determined using testing methods commonly used in the art. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0090] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: pole group; The outer casing includes a housing and a cover plate, wherein the cover plate covers an opening on one side of the housing to form a closed space for receiving the electrode assembly, and the cover plate is provided with a liquid injection hole; Electrode terminals are disposed in the housing and electrically connected to the electrode assembly; The cover plate has a liquid-separating groove on its surface away from the electrode assembly along the thickness direction, and the liquid-separating groove is located between the electrode terminal and the liquid injection hole.

2. The battery cell according to claim 1, characterized in that, Along the width direction of the cover plate, the two ends of the liquid-separating groove extend to the two edges of the cover plate, respectively.

3. The battery cell according to claim 2, characterized in that, Along the length of the cover plate, liquid-separating grooves are provided on both sides of the injection hole.

4. The battery cell according to claim 3, characterized in that, Along the length of the cover plate, a plurality of liquid-separating grooves are provided on each side of the injection hole, and the plurality of liquid-separating grooves are spaced apart along the length of the cover plate.

5. The battery cell according to claim 4, characterized in that, The number of the plurality of liquid separators ranges from 2 to 5.

6. The battery cell according to claim 1, characterized in that, Along the thickness direction of the cover plate, the depth of the liquid-separating groove is h, satisfying: 0.5mm≤h≤1mm; and / or, along the length direction of the cover plate, the width of the liquid-separating groove is a, satisfying: 1mm≤a≤2mm.

7. The battery cell according to any one of claims 1-6, characterized in that, The cover plate includes a boss portion and two flat plate portions located on both sides of the boss portion along the length direction of the cover plate. The electrode terminal is disposed on the flat plate portion, and the liquid injection hole and the liquid isolation groove are disposed on the boss portion. Along the thickness direction of the cover plate, the boss portion is higher than the electrode terminal relative to the top surface of the electrode assembly.

8. The battery cell according to claim 7, characterized in that, Along the thickness direction of the cover plate, the height difference H1 between the top surface of the boss portion facing away from the top surface of the electrode assembly and the height difference H1 between the electrode terminal and the top surface of the electrode assembly, satisfying: 3mm ≤ H1 ≤ 5mm; and / or, Along the thickness direction of the cover plate, the thickness of the flat plate portion is T1, and the thickness of the boss portion is T2, satisfying: 0.8 ≤ T2 / T1 ≤ 1.1, 2 mm ≤ T1 ≤ 2.5 mm; and / or, Along the length of the cover plate, the total length of the cover plate is L, satisfying: 150mm ≤ L ≤ 300mm; and / or, Along the width direction of the cover plate, the total width of the cover plate is W, which satisfies: 25mm≤L≤75mm.

9. The battery cell according to claim 7, characterized in that, Each of the plate portions is provided with a mounting hole, one end of the electrode terminal passes through the mounting hole, and the distance between two mounting holes along the length direction of the cover plate is L3; a first insulating member is provided between each electrode terminal and the cover plate, and the distance between two first insulating members along the length direction of the cover plate is L2; ​​the length of the boss portion along the length direction of the cover plate is L1; satisfying: 3mm≤(L2-L1) / 2≤10mm; and / or, 20mm≤(L3-L1) / 2≤25mm; preferably, along the length direction of the cover plate, the distance between the mounting hole and the nearest end of the cover plate is A, satisfying: 20mm≤A≤30mm.

10. The battery cell according to claim 1, characterized in that, The electrode assembly includes a first electrode plate, the first electrode plate includes a first current collector and a first tab connected to the end of the first current collector, the first electrode plate has n layers, the thickness of a single layer of the first current collector is c, and the total thickness of the first tab along the stacking direction of the first electrode plate is t, satisfying: t=nc; A second insulating element is provided between the cover plate and the electrode group. The second insulating element is provided with an electrode lug groove that avoids the first electrode lug. The height of the electrode lug groove along the thickness direction of the cover plate is H2, which satisfies: H2=(5~7)nc.

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