Battery cell, battery, and electric device

Abstract

A battery monomer (20), a battery (100) and an electric device. The battery monomer (20) comprises a shell (21) and a pressure relief structure (214), the shell (21) has a wall part (211), and the pressure relief structure (214) is arranged on the wall part (211). The pressure relief structure (214) is provided with a first groove (2143), and the pressure relief structure (214) is configured to be capable of being broken along at least a part of the first groove (2143) when the battery monomer (20) is relieved. Wherein, the first groove (2143) comprises at least one groove segment, the groove segment comprises a groove bottom surface (21431) and two groove side surfaces (21432), the two groove side surfaces (21432) are oppositely arranged along the width direction of the groove segment, the groove bottom surface (21431) and the at least one groove side surface (21432) are transitioned through a round corner (21433), the radius of the round corner (21433) is r, the width of a groove opening (21435) of the groove segment is a, and 0.08<=r / a<=0.4 is satisfied. By making the groove bottom surface (21431) and the at least one groove side surface (21432), the stress concentration of the groove segment is facilitated to be reduced, the risk of the first groove (2143) being broken in advance is reduced, and the service life of the battery monomer (20) is facilitated to be improved. When 0.08<=r / a<=0.4 is satisfied, the service life of the battery monomer (20) and the timeliness of the pressure relief of the battery monomer (20) can be considered.

Description

Battery cell, battery and electric device

[0001] Cross-reference to related applications

[0002] This application claims priority to the Chinese patent application with the title "Battery cell, battery and electric device" filed on May 16, 2024 (application number: 202421064601.4), the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the field of batteries, in particular to a battery cell, a battery and an electric device. BACKGROUND

[0004] Batteries are widely used in the field of new energy, for example, electric vehicles, new energy vehicles, etc. New energy vehicles and electric vehicles have become a new trend in the development of the automobile industry. The development of battery technology needs to consider various design factors, such as energy density, discharge capacity, charge-discharge rate, and other performance parameters. In addition, the service life of the battery also needs to be considered. However, the service life of the current battery is relatively short.

[0005] SUMMARY

[0006] The purpose of the embodiments of the present application is to provide a battery cell, a battery and an electric device, which aims to improve the problem of short service life of the battery in the related art.

[0007] In a first aspect, the embodiments of the present application provide a battery cell, which comprises a shell and a pressure relief structure, the shell has a wall portion; the pressure relief structure is arranged on the wall portion, the pressure relief structure is provided with a first groove, and the pressure relief structure is configured to be able to crack along at least part of the first groove when the battery cell is relieved of pressure; wherein the first groove comprises at least one groove segment, the groove segment comprises a groove bottom surface and two groove side surfaces, the two groove side surfaces are oppositely arranged along the width direction of the groove segment, and the groove bottom surface and at least one groove side surface are transitioned by a rounded corner.

[0008] In the above technical solution, the battery cell is provided with a pressure relief structure, the pressure relief structure is provided with a first groove, and the pressure relief structure can crack along at least part of the first groove when the battery cell is relieved of pressure, thereby facilitating the relief of the pressure inside the battery cell. The first groove comprises at least one groove segment, the groove segment comprises a groove bottom surface and two groove side surfaces oppositely arranged along the width direction of the groove segment, and the groove bottom surface and at least one groove side surface are transitioned by a rounded corner, which is beneficial to alleviate the stress concentration of the groove segment, reduce the strain of the groove segment, and reduce the risk of premature cracking of the first groove, thereby being beneficial to improving the service life of the battery cell.

[0009] As an optional technical solution of the embodiment of the application, the radius of the rounded corner is r, and the width of the notch of the groove section is a, and the following is met: 0.08≤r / a≤0.4, and optionally, 0.12≤r / a≤0.3.

[0010] In the above technical solution, when r / a≥0.08, the radius of the rounded corner is relatively large, the effect of slowing down the stress concentration of the groove section is good, the strain of the groove section can be effectively reduced, the risk of the first groove cracking in advance is reduced, thereby the life of the battery cell is improved. When r / a≤0.4, the radius of the rounded corner is not too large, the degree of stress concentration of the groove section is not too small, thereby the groove section can be timely cracked when the battery cell is pressure released, and the timeliness of the battery cell pressure release is improved. Therefore, when 0.08≤r / a≤0.4, the life of the battery cell and the timeliness of the battery cell pressure release can be considered.

[0011] When r / a≥0.12, the radius of the rounded corner is relatively larger, the effect of slowing down the stress concentration of the groove section is better, the strain of the groove section can be effectively reduced, the risk of the first groove cracking in advance is reduced, thereby the life of the battery cell is improved. When r / a≤0.3, the radius of the rounded corner is not too large, the degree of stress concentration of the groove section is not too small, thereby the groove section can be timely cracked when the battery cell is pressure released, and the timeliness of the battery cell pressure release is improved. Therefore, when 0.12≤r / a≤0.3, the life of the battery cell and the timeliness of the battery cell pressure release can be considered.

[0012] As an optional technical solution of the embodiment of the application, 0.03mm≤r≤0.15mm, and optionally, 0.06mm≤r≤0.1mm.

[0013] In the above technical solution, when r≥0.03mm, the radius of the rounded corner is relatively large, the effect of slowing down the stress concentration of the groove section is good, the strain of the groove section can be effectively reduced, the risk of the first groove cracking in advance is reduced, thereby the life of the battery cell is improved. When r≤0.15mm, the radius of the rounded corner is not too large, the degree of stress concentration of the groove section is not too small, thereby the groove section can be timely cracked when the battery cell is pressure released, and the timeliness of the battery cell pressure release is improved. Therefore, when 0.03mm≤r≤0.15mm, the life of the battery cell and the timeliness of the battery cell pressure release can be considered.

[0014] When r is greater than or equal to 0.06 mm, the radius of the rounded corner is relatively larger, and the effect of slowing down the stress concentration of the groove section is better, which can effectively reduce the strain of the groove section and reduce the risk of premature cracking of the first groove, thereby helping to improve the service life of the battery cell. When r is less than or equal to 0.1 mm, the radius of the rounded corner is not too large, and the degree of stress concentration of the groove section is not too small, thereby helping the groove section to timely crack when the battery cell is depressurized, and helping to improve the timeliness of the battery cell depressurization. Therefore, when 0.06 mm≤r≤0.1 mm, the service life of the battery cell and the timeliness of the battery cell depressurization can be better balanced.

[0015] As an optional technical solution of the embodiment of the present application, 0.08 mm≤a≤0.4 mm, and optionally, 0.26 mm≤a≤0.34 mm.

[0016] In the above technical solution, when a is greater than or equal to 0.08 mm, the width of the notch of the groove section is larger, thereby helping the groove section to timely crack when the battery cell is depressurized, and helping to improve the timeliness of the battery cell depressurization. When a is less than or equal to 0.4 mm, the width of the notch of the groove section is not too large, which can reduce the risk of the groove section cracking due to the change of the internal gas pressure of the battery cell, and help to improve the reliability of the battery cell. Therefore, when 0.08 mm≤a≤0.4 mm, the width of the notch of the groove section is moderate, the groove section neither easily cracks due to the change of the internal gas pressure of the battery cell, nor can timely crack when the battery cell is depressurized, which helps to improve the timeliness of the battery cell depressurization.

[0017] When a is greater than or equal to 0.26 mm, the width of the notch of the groove section is larger, thereby more helping the groove section to timely crack when the battery cell is depressurized, and helping to improve the timeliness of the battery cell depressurization. When a is less than or equal to 0.34 mm, the width of the notch of the groove section is not too large, which can reduce the risk of the groove section cracking due to the change of the internal gas pressure of the battery cell, and help to improve the reliability of the battery cell. Therefore, when 0.26 mm≤a≤0.34 mm, the reliability and the timeliness of the battery cell depressurization are better balanced.

[0018] As an optional technical solution of the embodiment of the present application, the pressure relief structure has a first surface and a second surface arranged opposite in the thickness direction of the wall portion, and is provided with a plurality of levels of grooves arranged in sequence from the first surface to the second surface. In two adjacent levels of the grooves, the groove section of a level of the grooves away from the first surface is arranged on the groove bottom surface of a level of the grooves close to the first surface. Among the plurality of levels of the grooves, the groove section of a level of the grooves farthest away from the first surface is the first groove.

[0019] In the technical solution, the multiple-stage grooves are arranged in the pressure relief structure in sequence from the first surface to the second surface, and the multiple-stage grooves can be formed step by step in the molding process, thereby reducing the molding force on the pressure relief structure and reducing the risk of cracks in the pressure relief structure. The pressure relief structure is less likely to fail due to cracks at the positions where the grooves are arranged, and the reliability of the battery cell is improved. In the process of forming the multiple-stage grooves, stamping or cold heading can be used. In this way, the groove walls will be cold-work-hardened (the crystal grain arrangement changes, causing lattice distortion and deformation, reducing the plasticity of the metal and increasing the hardness of the material), and the ability to resist external impact is enhanced, and the groove walls are less likely to be damaged by external impact. In this way, it is beneficial to reduce the risk of liquid leakage of the pressure relief structure.

[0020] As an optional technical solution of the embodiment of the present application, the first surface is a surface of the pressure relief structure facing away from the inside of the shell.

[0021] In the technical solution, the first groove is arranged on the surface of the pressure relief structure facing away from the inside of the shell, so that the first weak part needs to overcome less tension when it cracks and is easy to crack.

[0022] As an optional technical solution of the embodiment of the present application, the first groove includes multiple groove segments, the multiple groove segments are connected, and the multiple groove segments jointly define at least one predetermined pressure relief area configured to be opened to release the internal pressure of the battery cell when the pressure relief structure cracks along at least a portion of the first groove.

[0023] In the technical solution, the multiple groove segments define the predetermined pressure relief area, and the pressure relief structure can crack along the multiple groove segments to open the predetermined pressure relief area to release the pressure in the battery cell. Moreover, the connection position of the two groove segments is weaker and more likely to crack and open the predetermined pressure relief area for pressure relief, and the pressure relief area and the pressure relief rate of the battery cell can be further improved.

[0024] As an optional technical solution of the embodiment of the present application, the multiple groove segments include a first groove segment and a second groove segment, the first groove segment is connected to the second groove segment, and the first groove segment and the second groove segment jointly define at least one predetermined pressure relief area.

[0025] In the technical solution, the first groove segment and the second groove segment are connected to each other to jointly define at least one predetermined pressure relief area, which can increase the pressure relief area of the battery cell to improve the pressure relief rate of the battery cell. On the other hand, the connection position of the first groove segment and the second groove segment is weaker and more likely to crack and open the predetermined pressure relief area to release the internal pressure of the battery cell.

[0026] As an optional technical solution of the embodiment of the present application, the plurality of groove segments include a first groove segment, a second groove segment and a third groove segment, the first groove segment and the third groove segment are oppositely arranged, the second groove segment connects the first groove segment and the third groove segment, and the first groove segment, the second groove segment and the third groove segment jointly define at least one of the predetermined pressure relief zones.

[0027] In the above technical solution, the plurality of groove segments include a first groove segment, a second groove segment and a third groove segment, the second groove segment connects the first groove segment and the third groove segment, so that the pressure relief structure can be cracked along the first groove segment, the second groove segment and the third groove segment when the battery monomer is relieved, to open the predetermined pressure relief zone to release the internal pressure of the battery monomer, the connection positions of the first groove segment and the second groove segment and the connection positions of the first groove segment and the third groove segment are weaker and more easily cracked to open the predetermined pressure relief zone for pressure relief, and the pressure relief area and the pressure relief rate of the battery monomer can be further improved.

[0028] As an optional technical solution of the embodiment of the present application, the position where the second groove segment is connected with the first groove segment deviates from the two ends of the first groove segment, and the position where the second groove segment is connected with the third groove segment deviates from the two ends of the third groove segment, so that the predetermined pressure relief zone is formed on both sides of the second groove segment.

[0029] In the above technical solution, by setting the connection positions of the first groove segment and the second groove segment between the two ends of the first groove segment, and setting the connection positions of the third groove segment and the second groove segment between the two ends of the third groove segment, the first groove segment, the second groove segment and the third groove segment form a structure similar to "H", so that the two sides of the second groove segment of the first groove can form the predetermined pressure relief zone, and the two predetermined pressure relief zones can be opened in a split manner for pressure relief when the battery monomer is relieved, which is beneficial to further improve the pressure relief effect of the battery monomer and effectively improve the pressure relief rate of the battery monomer.

[0030] As an optional technical solution of the embodiment of the present application, the first groove extends along an arc trajectory.

[0031] In the above technical solution, by making the first groove extend along an arc trajectory, the first groove can define a larger predetermined pressure relief zone, and when the battery monomer is relieved, the predetermined pressure relief zone opens a larger opening, thereby facilitating the rapid pressure relief of the battery monomer.

[0032] As an optional technical solution of the embodiment of the present application, the pressure relief structure is integrally formed with the wall portion.

[0033] In the above technical solution, the pressure relief structure is integrally formed with the wall portion, without the need for additional welding or bonding processes, which is beneficial to reduce the risk of liquid leakage of the pressure relief structure. Moreover, during production, the initiation pressure of the processed plurality of battery monomers is more consistent.

[0034] As an optional technical solution of the embodiment of the present application, the pressure relief structure is arranged separately from the wall part, the wall part is provided with a pressure relief hole, and the pressure relief structure is mounted on the wall part and covers the pressure relief hole.

[0035] In the above technical solution, the pressure relief structure is arranged separately from the wall part and mounted on the wall part, so as to facilitate the manufacturing.

[0036] As an optional technical solution of the embodiment of the present application, the shell comprises a shell body and an end cover, the shell body has an opening, and the end cover is connected to the shell body and closes the opening; wherein the end cover is the wall part, or the shell body comprises the wall part.

[0037] In the above technical solution, when the end cover is the wall part, the pressure relief structure is arranged on the end cover, which is simple and convenient to manufacture. When the shell body comprises the wall part, the pressure relief structure is arranged on one wall of the shell body, and the fluid medium sprayed by the pressure relief structure is not easy to act on other electrical connection structures on the end cover, which is beneficial to reduce the risk of short circuit of the battery monomer.

[0038] In a second aspect, the embodiment of the present application further provides a battery, which comprises the battery monomer described above.

[0039] In a third aspect, the embodiment of the present application further provides a power utilization device, which comprises the battery monomer described above. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0041] Fig. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application;

[0042] Fig. 2 is an exploded view of a battery provided by some embodiments of the present application;

[0043] Fig. 3 is a structural schematic diagram of a battery monomer provided by some embodiments of the present application;

[0044] Fig. 4 is an exploded view of a battery monomer provided by some embodiments of the present application;

[0045] Fig. 5 is a bottom view of a shell of a battery monomer provided by some embodiments of the present application;

[0046] Fig. 6 is a partial sectional view of a shell of a battery monomer provided by some embodiments of the present application;

[0047] Fig. 7 is a partial enlarged view of the shell shown in Fig. 6 at A;

[0048] Fig. 8 is a partial enlarged view of Fig. 7 at B;

[0049] Fig. 9 is a bottom view of a shell of a battery cell according to yet other embodiments of the present application;

[0050] Fig. 10 is a bottom view of a shell of a battery cell according to still other embodiments of the present application.

[0051] Fig. 10 is a bottom view of a shell of a battery cell according to still other embodiments of the present application. DETAILED DESCRIPTION

[0052] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0053] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing the objects of the specific embodiments, and are not intended to limit the present application; the specification, claims and above description of drawings of the present application, the terms "include" and "have" and any variations thereof are intended to cover the non-exclusive inclusion. The specification and claims of the present application or the above description of drawings, the terms "first", "second" and the like are used to distinguish different objects, and are not intended to describe a particular order or primary and secondary relationship.

[0054] Reference to an "embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another.

[0055] In the description of the application, it is necessary to point out that, unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", "attach" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0056] The term "and / or" in this application is only to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. In addition, the character " / " in this application generally represents that the front and rear associated objects have an "or" relationship.

[0057] In the embodiments of the application, the same reference signs represent the same parts, and for the sake of brevity, the detailed description of the same parts is omitted in different embodiments. It should be understood that the thickness, length and width of various components in the embodiments of the application shown in the drawings, and the overall thickness, length and width of the integrated device are only exemplary and should not constitute any limitation on the application.

[0058] "Multiple" appearing in this application means more than two (including two).

[0059] In the embodiments of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging.

[0060] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead-acid battery, etc. The embodiments of the application are not limited in this regard.

[0061] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of the battery cell, active ions (such as lithium ions) are inserted and extracted between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, which can prevent the positive and negative electrodes from short-circuiting, and at the same time, the active ions can pass through.

[0062] In some embodiments, the cathode can be a cathode sheet, which can include a cathode current collector and a cathode active material disposed on at least one surface of the cathode current collector.

[0063] As an example, the cathode current collector has two surfaces opposite in the thickness direction thereof, and the cathode active material is disposed on either one or both of the two surfaces of the cathode current collector.

[0064] As an example, the cathode current collector can employ a metal foil or a composite current collector. For example, as the metal foil, aluminum with silver plating on the surface, stainless steel with silver plating on the surface, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, or titanium, etc. can be employed. The composite current collector 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, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0065] As an example, the cathode active material can include at least one of lithium-containing phosphates, lithium transition metal oxides, and modified compounds thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery cathode active material can also be used. These cathode active materials can be used alone only one or two or more can be used in combination. Among them, examples of the lithium-containing phosphates can include, but are not limited to, at least one of lithium iron phosphate (such as LiFeP04 (which can also be referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnP04), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon. Examples of the lithium transition metal oxides can include, but are not limited to, lithium cobalt oxide (such as LiCo02), lithium nickel oxide (such as LiNi02), lithium manganese oxide (such as LiMn02, LiMn204), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 02 (which can also be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 02 (which can also be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 02 (which can also be referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 02 (which can also be referred to as NCM622 LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to as NCM 811 LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof.

[0066] In some embodiments, the positive electrode can employ a foam metal. The foam metal can be a foam nickel, a foam copper, a foam aluminum, a foam alloy, etc. When the foam metal is used as the positive electrode, the foam metal surface can not be provided with the positive electrode active material, or of course can be provided with the positive electrode active material. As an example, the foam metal can also be filled or / and deposited with a lithium source material, a potassium metal or a sodium metal, the lithium source material being a lithium metal and / or a lithium-rich material.

[0067] In some embodiments, the negative electrode can be a negative electrode sheet, which can include a negative electrode current collector.

[0068] As an example, the negative electrode current collector can employ a metal foil, a foam metal or a composite current collector. For example, as the metal foil, silver surface treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, nickel or titanium, etc. can be employed. The foam metal can be a foam nickel, a foam copper, a foam aluminum, a foam alloy, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0069] As an example, the negative electrode sheet can include the negative electrode current collector and the negative electrode active material provided on at least one surface of the negative electrode current collector.

[0070] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode active material is provided on any one or both of the two opposite surfaces of the negative electrode current collector.

[0071] As an example, the negative active material can employ a negative active material for a battery cell known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery negative active material can also be used. These negative active materials can be used alone or in combination of two or more.

[0072] In some embodiments, the material of the positive current collector can be aluminum, and the material of the negative current collector can be copper.

[0073] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0074] In some embodiments, the separator is a separator film. The separator film can be of various types, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0075] As an example, the material of the separator film can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film. When the separator film is a multi-layer composite film, the materials of the respective layers can be the same or different. The separator can be a separate component located between the positive and negative electrodes, or can be attached to the surface of the positive and negative electrodes.

[0076] In some embodiments, the separator is a solid-state electrolyte. The solid-state electrolyte is disposed between the positive electrode and the negative electrode, and functions to transport ions and separate the positive and negative electrodes.

[0077] In some embodiments, the battery cell further includes an electrolyte that functions to conduct ions between the positive and negative electrodes. The electrolyte can be in a liquid state, a gel state, or a solid state. Among them, the liquid electrolyte includes an electrolyte salt and a solvent.

[0078] In some embodiments, the electrolyte salt can include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoroboric oxalate, lithium boric oxalate, lithium difluorophosphoric boric oxalate, and lithium tetrafluorophosphoric boric oxalate.

[0079] In some embodiments, the solvent can include at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, butyl sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent can also be selected from ether solvents. The ether solvents can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0080] In some embodiments, the gel electrolyte includes a polymer as a skeleton network of the electrolyte, and an ionic liquid-lithium salt.

[0081] In some embodiments, the solid electrolyte includes a polymer solid electrolyte, an inorganic solid electrolyte, and a composite solid electrolyte.

[0082] As an example, the polymer solid electrolyte can be a polyether (polyethylene oxide), a polysiloxane, a polycarbonate, a polyacrylonitrile, a polyvinylidene fluoride, a polymethyl methacrylate, a single-ion polymer, a polyionic liquid-lithium salt, cellulose, or the like.

[0083] As an example, the inorganic solid electrolyte can include one or more of an oxide solid electrolyte (crystalline perovskite, sodium superionic conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superionic conductor (lithium germanium phosphorus sulfide, argyrodite), amorphous sulfide), and a halide solid electrolyte, a nitride solid electrolyte, and a hydride solid electrolyte.

[0084] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0085] In some embodiments, the electrode assembly is a wound structure. The positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0086] In some embodiments, the electrode assembly is a stacked structure.

[0087] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be provided, and the plurality of positive electrode sheets and the plurality of negative electrode sheets can be alternately stacked.

[0088] As an example, a plurality of positive electrode sheets can be provided, and the negative electrode sheet can be folded to form a plurality of folded segments that are stacked, and one positive electrode sheet can be interposed between adjacent folded segments.

[0089] As an example, the positive electrode sheet and the negative electrode sheet can each be folded to form a plurality of folded segments that are stacked.

[0090] As an example, the separators can be provided in plurality, each provided between any adjacent positive electrode sheet or negative electrode sheet.

[0091] As an example, the separators can be provided in plurality, each provided between any adjacent positive electrode sheet or negative electrode sheet.

[0092] In some embodiments, the electrode assembly can have a shape of a cylinder, a flat, or a multi-prism, etc.

[0093] In some embodiments, the electrode assembly can be provided with tabs, which can lead current out of the electrode assembly. The tabs can include positive tabs and negative tabs.

[0094] In some embodiments, the battery cell can include a casing. The casing can be used to enclose components such as the electrode assembly and the electrolyte. The casing can be a steel casing, an aluminum casing, a plastic casing (e.g., polypropylene), a composite metal casing (e.g., a copper-aluminum composite casing), or an aluminum-plastic film, etc.

[0095] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes, which can include, but are not limited to, a square battery cell, a blade battery cell, a multi-prismatic battery cell (e.g., a hexagonal battery cell), etc.

[0096] A battery as referred to in embodiments of the present application can refer to a single physical module that includes one or more battery cells to provide higher voltage and capacity.

[0097] In some embodiments, the battery can be a battery module, in which a plurality of battery cells are arranged and fixed to form a battery module.

[0098] In some embodiments, the battery can be a battery pack, which can include a box and battery cells, which can be contained in the box.

[0099] In some embodiments, the box can be part of a chassis structure of a vehicle. For example, part of the box can be at least part of a floor of the vehicle, or part of the box can be at least part of a cross beam and a longitudinal beam of the vehicle.

[0100] In some embodiments, the battery can be an energy storage device. The energy storage device can include an energy storage container, an energy storage cabinet, etc.

[0101] The development of battery technology needs to take into account various design factors, such as performance parameters such as energy density, discharge capacity, and charge-discharge rate. In addition, the life of the battery also needs to be considered. However, the current battery has a relatively short life.

[0102] For the battery monomer, in order to improve the reliability of the battery monomer, the prior art is to provide a pressure relief mechanism on the battery monomer, and the pressure relief mechanism is provided with a notch groove. When the internal pressure of the battery monomer reaches the detonation pressure, the notch groove is cracked to release the internal pressure of the battery monomer, thereby reducing the risk of explosion and fire of the battery monomer.

[0103] However, during the charging and discharging cycle of the battery monomer, the electrode assembly will expand, and the expansion of the electrode assembly will squeeze the shell of the battery monomer, causing the shell to deform, thereby pulling the notch groove of the pressure relief mechanism, causing the notch groove to produce a large strain. The battery monomer expands greatly in the fully charged state, and the expansion force is small in the discharged state. There is a large amplitude of expansion force in the process of charging and discharging, coupled with the gas generated inside the battery monomer and different external constraint conditions, which will cause the notch groove to produce obvious strain, strain amplitude and strain accumulation, etc. The notch groove is cracked in advance, and problems such as liquid leakage occur, resulting in a short service life of the battery monomer.

[0104] Therefore, the battery monomer provided by the embodiments of the present application includes a shell and a pressure relief structure. The shell has a wall portion, and the pressure relief structure is arranged on the wall portion. The pressure relief structure is provided with a first groove, and the pressure relief structure is configured to be cracked along at least part of the first groove when the battery monomer is relieved. The first groove includes at least one groove segment, and the groove segment includes a groove bottom surface and two groove side surfaces arranged opposite to each other along the width direction of the groove segment. The groove bottom surface and the at least one groove side surface are transitioned by a rounded corner.

[0105] The battery monomer is provided with a pressure relief structure, and the pressure relief structure is provided with a first groove. The pressure relief structure can be cracked along at least part of the first groove when the battery monomer is relieved, thereby facilitating the release of the internal pressure of the battery monomer. The first groove includes at least one groove segment, and the groove segment includes a groove bottom surface and two groove side surfaces arranged opposite to each other along the width direction of the groove segment. By making the groove bottom surface and the at least one groove side surface transition by a rounded corner, the stress concentration of the groove segment is alleviated, the strain of the groove segment is reduced, and the risk of premature cracking of the first groove is reduced, thereby improving the service life of the battery monomer.

[0106] The battery monomer disclosed in the embodiments of the present application can be used in an electric device such as a vehicle, a ship or an aircraft, but is not limited thereto. The power supply system of the electric device can be composed of the battery monomer and the battery disclosed in the present application. In this way, the reliability of the battery monomer can be improved.

[0107] The embodiments of the present application provide a power consumption device using a battery as a power supply. The power consumption device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric automobile, a ship, a spacecraft and the like. The electric toy can include a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy and an electric aircraft toy, and the spacecraft can include an airplane, a rocket, a space shuttle and a spacecraft.

[0108] The following embodiments are described by taking a power consumption device as a vehicle as an example for convenience of description.

[0109] Referring to FIG. 1, FIG. 1 is a structural schematic diagram of a vehicle 1000 provided by some embodiments of the present application. The vehicle 1000 can be a fuel automobile, a gas automobile or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile or a range extended automobile. The vehicle 1000 is internally provided with a battery 100. The battery 100 can be arranged at the bottom of the vehicle 1000, or arranged at the head of the vehicle 1000, or arranged at the tail of the vehicle 1000. The battery 100 can be used for power supply of the vehicle 1000, for example, the battery 100 can be used as an operating power supply or a use power supply of the vehicle 1000. The vehicle 1000 can further include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to supply power to the motor 300, for example, to meet the working power demand of the vehicle 1000 during starting, navigation and driving.

[0110] In some embodiments of the present application, the battery 100 can not only be used as an operating power supply or a use power supply of the vehicle 1000, but also be used as a driving power supply of the vehicle 1000, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1000.

[0111] Referring to FIG. 2 and FIG. 3, FIG. 2 is a structural explosion diagram of the battery 100 provided by some embodiments of the present application, and FIG. 3 is a structural schematic diagram of a battery monomer 20 provided by some embodiments of the present application. The battery 100 includes a box body 10 and the battery monomer 20. The battery monomer 20 is used to be accommodated in the box body 10.

[0112] The box 10 is configured to provide an assembly space for the battery cell 20. The box 10 can have various structures. In some embodiments, the box 10 can include a first box body 11 and a second box body 12. The first box body 11 and the second box body 12 are coupled to each other to define an assembly space for accommodating the battery cell 20. The second box body 12 can be a hollow structure with one end open, and the first box body 11 can be a plate structure. The first box body 11 is coupled to the open end of the second box body 12 to define the assembly space together with the second box body 12. Alternatively, the first box body 11 and the second box body 12 can both be hollow structures with one end open. The open end of the first box body 11 is coupled to the open end of the second box body 12.

[0113] The box 10 formed by the first box body 11 and the second box body 12 can have various shapes, such as a cylinder, a cuboid, a square, etc. For example, as shown in FIG. 2, the box 10 has a cuboid shape.

[0114] In the battery 100, the battery cell 20 disposed in the box 10 can be one or a plurality of battery cells. When the battery cell 20 disposed in the box 10 is a plurality of battery cells, the plurality of battery cells 20 can be connected in series, in parallel, or in a mixed connection. The mixed connection means that the plurality of battery cells 20 are connected in series and in parallel. The plurality of battery cells 20 can be directly connected in series, in parallel, or in a mixed connection, and then the plurality of battery cells 20 can be accommodated in the box 10. Alternatively, the plurality of battery cells 20 can be connected in series, in parallel, or in a mixed connection to form a battery module, and then a plurality of battery modules can be connected in series, in parallel, or in a mixed connection to form a whole, which is accommodated in the box 10.

[0115] In some embodiments, the battery 100 can further include other structures. For example, the battery 100 can further include a busbar member configured to connect the plurality of battery cells 20 to achieve electrical connection between the plurality of battery cells 20.

[0116] Each of the battery cells 20 can be a secondary battery or a primary battery, and can be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can have a cuboid, a cylinder, a prism, or other shapes, etc. For example, as shown in FIG. 3, the battery cell 20 has a cuboid shape.

[0117] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7 and FIG. 8, FIG. 4 is an exploded view of the battery cell 20 according to some embodiments of the present application. FIG. 5 is a bottom view of the shell 21 of the battery cell 20 according to some embodiments of the present application. FIG. 6 is a partial sectional view of the shell 21 of the battery cell 20 according to some embodiments of the present application. FIG. 7 is a partial enlarged view of A of the shell 21 shown in FIG. 6. FIG. 8 is a partial enlarged view of B of FIG. 7. The embodiments of the present application provide a battery cell 20, which comprises a shell 21 having a wall portion 211 and a pressure relief structure 214 arranged on the wall portion 211. The pressure relief structure 214 is provided with a first groove 2143, and the pressure relief structure 214 is configured to be able to split along at least a portion of the first groove 2143 when the battery cell 20 is relieved of pressure. The first groove 2143 comprises at least one groove segment, and the groove segment comprises a groove bottom surface 21431 and two groove side surfaces 21432 arranged opposite to each other along the width direction of the groove segment, and the groove bottom surface 21431 and the at least one groove side surface 21432 are transitioned by a rounded corner 21433.

[0118] The battery cell 20 refers to the smallest unit that constitutes the battery 100.

[0119] The shell 21 comprises an end cover 216 and a shell body 215, and the shell body 215 has an opening 2151, and the end cover 216 is connected to the shell body 215 and closes the opening 2151.

[0120] The end cover 216 refers to a component that covers the opening 2151 of the shell body 215 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cover 216 can be adapted to the shape of the shell body 215 to fit the shell body 215. Optionally, the end cover 216 can be made of a material with certain hardness and strength, such as aluminum alloy, so that the end cover 216 is not easy to deform when subjected to extrusion and collision, so that the battery cell 20 can have higher structural strength, and the safety performance can also be improved. The material of the end cover 216 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special limitations thereon. In some embodiments, the battery cell 20 further comprises an insulating member arranged on the inner side of the end cover 216, and the insulating member can be used to isolate the electrical connection components in the shell body 215 from the end cover 216 to reduce the risk of short circuit. Exemplarily, the insulating member can be plastic, rubber, etc.

[0121] The shell 215 is a component for fitting the end cover 216 to form an internal environment of the battery cell 20, where the formed internal environment can be used to accommodate the electrode assembly 22, electrolyte, and other components. The shell 215 and the end cover 216 can be independent components, and an opening 2151 can be provided on the shell 215, and the end cover 216 is fitted to cover the opening 2151 to form the internal environment of the battery cell 20. Without limitation, the end cover 216 and the shell 215 can also be integrated, specifically, the end cover 216 and the shell 215 can form a common joint surface before other components enter the shell, and when it is necessary to seal the internal environment of the shell 215, the end cover 216 is fitted to cover the shell 215. The shell 215 can be various shapes and sizes, such as a cuboid, a cylinder, a hexagonal prism, etc. Specifically, the shape of the shell 215 can be determined according to the specific shape and size of the electrode assembly 22. The material of the shell 215 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special limitations on this.

[0122] The electrode assembly 22 is a component where electrochemical reactions occur in the battery cell 20. One or more electrode assemblies 22 can be contained in the housing 21. The electrode assembly 22 is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and an isolation film is usually provided between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet have a portion with active material constituting a main body of the electrode assembly 22, and a portion without active material constituting a tab 221 of each of the positive electrode sheet and the negative electrode sheet. The positive electrode tab and the negative electrode tab can be located together at one end of the main body or respectively at both ends of the main body. During the charging and discharging process of the battery 100, the positive electrode active material and the negative electrode active material react with the electrolyte.

[0123] The wall portion 211 can be the end cover 216 of the housing 21, or a wall of the shell 215 of the housing 21. Exemplarily, in FIGS. 3 and 4, the wall portion 211 is a bottom wall of the shell 215 opposite to the end cover 216. In other embodiments, the wall portion 211 can also be a side wall 212 of the shell 215 adjacent to and connected to the end cover 216.

[0124] The pressure relief structure 214 can be a component mounted on the wall portion 211, in which case the pressure relief structure 214 is separately provided and connected to the wall portion 211. For example, the pressure relief structure 214 is a rupture disc mounted on the wall portion 211. The pressure relief structure 214 can also be a part of the wall portion 211, in which case the pressure relief structure 214 is integrally formed with the wall portion 211. The wall of the shell 21 that is the wall portion 211 can be determined by the position at which the pressure relief structure 214 is provided. For example, when the pressure relief structure 214 is provided at the end cover 216, the end cover 216 is the wall portion 211. When the pressure relief structure 214 is provided at the bottom wall of the shell 215, the bottom wall is the wall portion 211. When the pressure relief structure 214 is provided at the side wall 212 of the shell 215, the side wall 212 is the wall portion 211.

[0125] The first groove 2143 functions as a pressure relief structure, and is configured to enable the pressure relief structure 214 to break along the first groove 2143 when the internal pressure or temperature of the battery cell 20 reaches an initiation pressure, so as to release the pressure inside the battery cell 20.

[0126] Optionally, the first groove 2143 can be provided on the side of the pressure relief structure 214 facing the inside of the shell 21, or on the side of the pressure relief structure 214 facing away from the inside of the shell 21. For example, in FIGS. 5 and 6, the first groove 2143 is provided on the side of the pressure relief structure 214 facing away from the inside of the shell 21, i.e., on the surface of the side of the pressure relief structure 214 facing away from the inside of the shell 21.

[0127] The first groove 2143 can be formed in various ways, such as by stamping or cold heading. When the first groove 2143 is formed by stamping or cold heading, the walls of the first groove 2143 are hardened by cold working (the arrangement of crystal grains changes, causing the crystal lattice to twist and distort, which reduces the plasticity of the metal and increases the hardness of the material), which enhances the ability of the walls of the first groove 2143 to resist external impacts and makes them less likely to be damaged by external impacts. This advantageously reduces the risk of liquid leakage from the pressure relief structure 214.

[0128] The first groove 2143 can include one groove segment, two groove segments, three groove segments, or more than three groove segments. The groove segments can extend along a straight trajectory or along an arcuate trajectory. Each groove segment includes a groove bottom surface 21431 and two groove side surfaces 21432. The groove bottom surface 21431 is the surface of the groove segment that is opposite the groove opening and farthest from the groove opening. One end of each groove side surface 21432 is connected to the groove bottom surface 21431, and the other end of each groove side surface 21432 is configured to bound the groove opening. The two groove side surfaces 21432 are oppositely disposed along the width direction of the groove segment.

[0129] Referring to FIGS. 6, 7, and 8, the width direction of the groove segment is the X direction shown in the figures.

[0130] The "transition of the groove bottom surface 21431 and the at least one groove side surface 21432 through the round corner 21433" can also be understood as that the groove bottom surface 21431 and the at least one groove side surface 21432 are connected through an arc surface. The groove bottom surface 21431 can transition with one groove side surface 21432 through the round corner 21433, or the groove bottom surface 21431 can transition with both groove side surfaces 21432 through the round corner 21433.

[0131] The battery cell 20 is provided with a pressure relief structure 214, the pressure relief structure 214 is provided with a first groove 2143, and the pressure relief structure 214 can be cracked along at least a part of the first groove 2143 when the battery cell 20 is relieved, thereby facilitating the relief of the pressure inside the battery cell 20. The first groove 2143 includes at least one groove segment, the groove segment includes a groove bottom surface 21431 and two groove side surfaces 21432 oppositely arranged along the width direction of the groove segment, and by making the groove bottom surface 21431 and the at least one groove side surface 21432 transition through the round corner 21433, it is beneficial to alleviate the stress concentration of the groove segment, reduce the strain of the groove segment, and reduce the risk of early cracking of the first groove 2143, thereby being beneficial to improving the service life of the battery cell 20.

[0132] In some embodiments, referring to FIG. 4, the battery cell 20 can further include an electrode terminal 23, the electrode terminal 23 is insulatively mounted on the shell 21, and the electrode terminal 23 is electrically connected with the electrode assembly 22 to output or input the electric energy of the battery cell 20.

[0133] It should be noted that the electrode terminal 23 is insulatively mounted on the shell 21, that is, no electrical connection is formed between the electrode terminal 23 and the shell 21.

[0134] In FIGS. 3 and 4, the battery cell 20 includes two electrode terminals 23, the two electrode terminals 23 are arranged on the end cover 216 in a spaced manner, and correspondingly, each electrode assembly 22 has two tabs 221, and the polarities of the two tabs 221 are opposite, and the two electrode terminals 23 are electrically connected with the two tabs 221 of the electrode assembly 22 respectively to realize the input or output of the positive electrode and the negative electrode of the battery cell 20.

[0135] Exemplarily, the material of the electrode terminal 23 can also be various, for example, the material of the electrode terminal 23 can be copper, iron, aluminum, steel or aluminum alloy, etc.

[0136] Optionally, the structure that the electrode terminal 23 is mounted on the shell 21 can be various, and exemplarily, in FIG. 3 and FIG. 4, both of the electrode terminals 23 are mounted on the end cover 216 of the shell 21. Of course, the structure of the battery monomer 20 is not limited to this, and in other embodiments, both of the electrode terminals 23 can be mounted on the shell body 215 of the shell 21, and likewise, one of the electrode terminals 23 can be mounted on the shell body 215 of the shell 21, and the other electrode terminal 23 can be mounted on the end cover 216 of the shell 21.

[0137] In some embodiments, referring to FIG. 4, the battery monomer 20 can further include two current collecting members 24, both of which are arranged in the shell 21, and each of the current collecting members 24 is used to connect one electrode terminal 23 and the tab 221 with the same polarity in the plurality of electrode assemblies 22, so as to realize the electrical connection between the electrode terminal 23 and the electrode assembly 22, and facilitate to reduce the assembly difficulty between the tab 221 and the electrode terminal 23.

[0138] Exemplarily, the material of the current collecting member 24 can also be various, for example, the material of the current collecting member 24 can be copper, iron, aluminum, steel or aluminum alloy, etc.

[0139] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7 and FIG. 8, in some embodiments, the radius of the rounded corner 21433 is r, and the width of the slot mouth 21435 of the slot section is a, and it is satisfied that 0.08≤r / a≤0.4.

[0140] r represents the radius of the rounded corner 21433. a represents the length of the slot mouth 21435 of the slot section in the width direction of the slot section, that is, the width of the slot mouth 21435 of the slot section. r / a represents the ratio of the radius of the rounded corner 21433 to the width of the slot mouth 21435 of the slot section.

[0141] The ratio of the radius of the rounded corner 21433 to the width of the slot mouth 21435 of the slot section can be: r / a=0.08, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.34, 0.36, 0.38, 0.4, etc.

[0142] When r / a≥0.08, the radius of the fillet 21433 is relatively large, which slows down the stress concentration of the groove section, effectively reduces the strain of the groove section, and reduces the risk of the first groove 2143 cracking in advance, thereby helping to improve the service life of the battery monomer 20. When r / a≤0.4, the radius of the fillet 21433 is not too large, and the stress concentration of the groove section is not too small, thereby helping the groove section to crack in time when the battery monomer 20 is depressurized, and helping to improve the timeliness of the battery monomer 20. Therefore, when 0.08≤r / a≤0.4, the service life of the battery monomer 20 and the timeliness of the battery monomer 20 can be considered.

[0143] Optionally, 0.12≤r / a≤0.3.

[0144] The ratio of the radius of the fillet 21433 to the width of the notch 21435 of the groove section can be: r / a=0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, etc.

[0145] When r / a≥0.12, the radius of the fillet 21433 is relatively large, which slows down the stress concentration of the groove section, effectively reduces the strain of the groove section, and reduces the risk of the first groove 2143 cracking in advance, thereby helping to improve the service life of the battery monomer 20. When r / a≤0.3, the radius of the fillet 21433 is not too large, and the stress concentration of the groove section is not too small, thereby helping the groove section to crack in time when the battery monomer 20 is depressurized, and helping to improve the timeliness of the battery monomer 20. Therefore, when 0.12≤r / a≤0.3, the service life of the battery monomer 20 and the timeliness of the battery monomer 20 can be considered.

[0146] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application more clear, the following will be further described in detail in combination with embodiments 1-10. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. The following description of at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor belong to the scope of protection of the present application.

[0147] Embodiment 1

[0148] The battery monomer 20 in each embodiment is prepared and tested according to the following method.

[0149] I. Preparation of the battery monomer 20

[0150] 1) Preparation of the positive electrode sheet

[0151] LiNi 0.7 Co 0.1 Mn 0.1 O2, a conductive agent Super P, and a binder polyvinylidene fluoride (PVDF) in N-methyl pyrrolidone (NMP) to form a positive electrode slurry, wherein the solid content in the positive electrode slurry is 50 wt%, and the mass ratio of LiNi 0.7 Co 0.1 Mn 0.1 O2, Super P, and PVDF is 8:1:1, the positive electrode slurry is coated on the upper and lower surfaces of the current collector aluminum foil, and after drying at 85°C and cold pressing, the edges are cut, the sheet is cut, and the strips are separated, and then the sheet is dried at 85°C under vacuum conditions for 4h to form a positive electrode sheet.

[0152] 2) Preparation of the negative electrode sheet

[0153] Graphite, a conductive agent Super P, a thickening agent carboxymethyl cellulose (CMC), and an adhesive styrene butadiene rubber (SBR) are mixed uniformly in deionized water to form a negative electrode slurry, wherein the solid content in the negative electrode slurry is 30 wt%, and the mass ratio of graphite, silicon monoxide, Super P, CMC, and the adhesive styrene butadiene rubber (SBR) in the solid components is 88:7:3:2, the negative electrode slurry is coated on the upper and lower surfaces of the current collector copper foil and dried at 85°C, and then cold pressed, the edges are cut, the sheet is cut, and the strips are separated, and then the sheet is dried at 120°C under vacuum conditions for 12h to form a negative electrode sheet.

[0154] 3) Preparation of the electrolyte

[0155] In an argon atmosphere glove box (H2O <0.1 ppm, O2 <0.1 ppm), a fully dried electrolyte salt LiPF6 is dissolved in a mixed solvent (the mixed solvent includes ethylene carbonate (EC) and diethyl carbonate (DEC), and the ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed in a mass ratio of 50:50), and after mixing uniformly, a liquid electrolyte with a concentration of 1 mol / L is obtained.

[0156] 4) Separator

[0157] A 16μm polyethylene film is used as the separator.

[0158] 5) Preparation of the battery cell 20

[0159] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order with the separator between the positive and negative electrode sheets to function as a separator between the positive and negative electrodes, and the electrode assembly 22 is obtained by winding. The electrode assembly 22 is placed in the aluminum case 21, and the electrolyte prepared above is injected into the dried case 21. The battery cell 20 is completed by packaging, standing, formation, shaping, capacity testing, and the like, and the first groove 2143 is formed on the wall portion 211 of the case 21 of the battery cell 20. The case 21 of the battery cell 20 of Example 1 is a rectangular parallelepiped structure, the housing 215 of the case 21 is a structure in which an opening 2151 is formed at one end, the wall opposite to the end cap 216 of the housing 215 is the wall portion 211, and the wall portion 211 is a rectangular wall. The first groove 2143 is an "H" shaped structure, that is, the first groove 2143 includes a first groove segment 2143a, a second groove segment 2143b, and a third groove segment 2143c, the second groove segment 2143b is connected between the first groove segment 2143a and the third groove segment 2143c, and the second groove segment 2143b is located in the middle of the wall portion 211 in the width direction of the wall portion 211. The thickness of the battery cell 20 is 39 mm, the width is 203 mm, the shoulder height (the dimension of the case 21 in the height direction) is 122.7 mm, and the capacity is 185 Ah.

[0160] The radius r of the rounded corner 21433 and the width a of the notch 21435 of the groove segment are measured by tomography and then by software.

[0161] The battery cells 20 of Examples 2 to 10 are prepared in the same manner as in Example 1, except that the radius r of the rounded corner 21433 and the width a of the notch 21435 of the groove segment are different, and the details are shown in Table 1.

[0162] II. Test of Performance Parameters

[0163] 1. Measurement method of cycle fatigue number of the battery cell 20

[0164] 1) A dedicated test jig is prepared. Specifically, the jig includes three 10 mm steel plates (first steel plate, second steel plate, and third steel plate), each of which can completely cover the large face of the battery cell 20 (the large face of the battery cell 20 refers to the surface of the outer surface of the case 21 with the largest area), the first steel plate and the third steel plate are located at both ends of the jig and are fixed by a bolt, the second steel plate is located between the first steel plate and the third steel plate, and the second steel plate is constrained by a guide rail, so that the second steel plate can only move in the thickness direction of the second steel plate.

[0165] 2) Install the battery monomer 20 between the first steel plate and the second steel plate, place the support structure between the one side large surface of the battery monomer 20 and the first steel plate, and the other side large surface and the second steel plate. The support structure can be a heat insulation pad or a water cooling plate (consistent with the material / structure between the two adjacent battery monomers 20 in the actual battery 100), which can be compressed to provide expansion space for the battery monomer 20 during the charge and discharge cycle aging process; the large surface of the battery monomer 20 is attached to the support structure, the first steel plate is attached to the corresponding support structure, and the second steel plate is attached to the corresponding support structure. A pressure sensor is provided between the second steel plate and the third steel plate.

[0166] 3) Adjust the position of the second steel plate by adjusting the pre-tightening force of the adjusting bolt, observe the pressure sensor, so that the initial extrusion force received by the battery monomer 20 is 2000N, and connect the positive electrode terminal and the negative electrode terminal of the battery monomer 20 to the charge and discharge equipment.

[0167] 4) Place the battery monomer 20 and the clamp in a constant temperature environment of 25±2℃, and start the test after the battery monomer 20 reaches temperature equilibrium.

[0168] 5) The test steps refer to the 6.4 chapter "Standard cycle life" of "GBT31484-2015 Electric Vehicle Power Storage Battery 100 Cycle Life Requirements and Test Methods", and the test cycle cutoff condition is changed to "stop testing until the first weak part 2144 of the wall part 211 is damaged".

[0169] Specifically, test according to the following steps:

[0170] a) discharge at 1I1(A) current to 2.8v;

[0171] b) rest for no less than 30min or the rest condition specified by the enterprise;

[0172] c) charge according to the method of "GBT31484-2015 Electric Vehicle Power Storage Battery 100 Cycle Life Requirements and Test Methods" 6.1.1.3;

[0173] d) rest for no less than 30min;

[0174] e) discharge at 1I1(A) current to 2.8v;

[0175] f) cycle according to b)~e) until the first groove 2143 of the wall part 211 is damaged to stop the test.

[0176] That is, the test process continuously observes the area of the wall part 211 of the battery monomer 20 where the first groove 2143 is provided until the area is damaged and leaks, and records the number of cycles as the number of cycle fatigue of the battery monomer 20. Among them, the more the number of cycle fatigue of the battery monomer 20, the smaller the probability of valve leakage caused by gas production of the battery monomer 20 in the long-term use process, and the longer the service life.

[0177] 2. Battery monomer 20 thermal runaway test method

[0178] 1. Select the heating plate according to the size of the battery monomer 20, and the size of the heating plate should cover the large face of the battery monomer 20 as much as possible (coverage area ≥ 60%);

[0179] 2. Charge the battery monomer 20 to 100% SOC before testing to ensure that the temperature of the battery monomer 20 is 25±5℃;

[0180] 3. Sensor arrangement:

[0181] 1) Temperature sensing line arrangement: paste one layer of Teflon on the center area of the two large faces of the battery monomer 20, arrange the temperature sensing line above the Teflon, and then paste another layer of Teflon;

[0182] 2) Voltage sampling line arrangement: paste one layer of Teflon on the positive electrode terminal, negative electrode terminal and shell 21 of the battery monomer 20, arrange the voltage sampling line above the Teflon, and then paste another layer of Teflon;

[0183] 3) Gas pipe arrangement: drill holes on the wall part 211 of the battery monomer 20, along the length direction of the wall part 211, the hole position is located at the midpoint position between the first groove 2143 and the side of the shell 215 (the outer surface of the wall adjacent to the wall part 211 along the length direction of the wall part 211), extend the gas pipe into the hole and seal it, and connect the gas pipe with the air pressure sensor;

[0184] 4) Connect the temperature sensing line, voltage sampling line and air pressure sensor to the data acquisition instrument to collect and analyze data in real time, and the collection frequency of the data acquisition instrument is ≤0.1S;

[0185] 4. Assembly fixture: cover the large face of the battery monomer 20 with the fixture, the clamping force is 3000N, and the arrangement order of the fixture, heating plate and battery monomer 20 is: fixture + heating plate + battery monomer 20 + fixture;

[0186] 5. Test: open the multi-channel temperature, voltage and air pressure data acquisition, then start the heating plate at a power of 500W to heat the battery monomer 20, until the battery monomer 20 is in thermal runaway.

[0187] 6. Obtain the pressure build-up duration of the battery monomer 20: determine the thermal runaway time and the valve opening time according to the multi-channel collected temperature, voltage and pressure data, and obtain the pressure build-up duration of the battery monomer 20 according to the pressure build-up duration = valve opening time - thermal runaway time.

[0188] Thermal runaway determination criteria: a) the trigger object generates voltage drop, and the drop is more than 25% of the initial voltage; b) the temperature of the detection point reaches the maximum working temperature specified by the manufacturer; c) the temperature rise rate dT / dt of the detection point is ≥1℃ / s, and lasts for more than 3s. When a) and c) or b) and c) occur, it is determined that thermal runaway occurs, and the thermal runaway time is determined.

[0189] Valve opening time determination: when the pressure decreases by more than 25%, it can be determined that the valve (the wall portion 211 is cracked along the first groove 2143) is opened, and the time when the pressure starts to decrease is the valve opening time.

[0190] III. Test results

[0191] The experimental results of examples 1-10 are shown in Table 1 below:

[0192] Table 1

[0193] Please refer to Table 1, as shown in Example 1, when r / a≥0.08, the radius of the fillet 21433 is relatively small, the effect of reducing stress concentration of the groove section is poor, the number of cycle fatigue of the battery monomer 20 is less, and the service life of the battery monomer 20 is shorter.

[0194] Please refer to Table 1, as shown in Examples 2-8, when 0.08≤r / a≤0.4, the number of cycle fatigue of the battery monomer 20 is more, the service life of the battery monomer 20 is longer, and the gas build-up duration of the battery monomer 20 is shorter, and the pressure relief timeliness of the battery monomer 20 is better.

[0195] Please refer to Table 1, as shown in Examples 9-10, when r / a≥0.4, the number of cycle fatigue of the battery monomer 20 is more, the service life of the battery monomer 20 is longer, but the gas build-up duration of the battery monomer 20 is also longer, and the pressure relief timeliness of the battery monomer 20 is poor.

[0196] In some embodiments, 0.03mm≤r≤0.15mm.

[0197] The radius of the fillet 21433 can be: r=0.03mm, 0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, etc.

[0198] When r≥0.03 mm, the radius of the fillet 21433 is relatively large, and the effect of slowing down the stress concentration of the groove segment is good, which can effectively reduce the strain of the groove segment and reduce the risk of early cracking of the first groove 2143, thereby helping to improve the service life of the battery monomer 20. When r≤0.15 mm, the radius of the fillet 21433 is not too large, and the degree of stress concentration of the groove segment is not too small, thereby helping the groove segment to timely crack when the battery monomer 20 is depressurized, and helping to improve the timeliness of the battery monomer 20. Therefore, when 0.03 mm≤r≤0.15 mm, the service life of the battery monomer 20 and the timeliness of the battery monomer 20 can be considered.

[0199] Optionally, 0.06 mm≤r≤0.1 mm.

[0200] The radius of the fillet 21433 can be: r=0.06 mm, 0.065 mm, 0.07 mm, 0.075 mm, 0.08 mm, 0.085 mm, 0.09 mm, 0.095 mm, 0.1 mm, etc.

[0201] When r≥0.06 mm, the radius of the fillet 21433 is relatively larger, and the effect of slowing down the stress concentration of the groove segment is better, which can effectively reduce the strain of the groove segment and reduce the risk of early cracking of the first groove 2143, thereby helping to improve the service life of the battery monomer 20. When r≤0.1, the radius of the fillet 21433 is not too large, and the degree of stress concentration of the groove segment is not too small, thereby helping the groove segment to timely crack when the battery monomer 20 is depressurized, and helping to improve the timeliness of the battery monomer 20. Therefore, when 0.06 mm≤r≤0.1 mm, the service life of the battery monomer 20 and the timeliness of the battery monomer 20 can be considered.

[0202] In some embodiments, 0.08 mm≤a≤0.4 mm.

[0203] The width of the notch 21435 of the groove segment can be: a=0.08 mm, 0.1 mm, 0.12 mm, 0.14 mm, 0.16 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.24 mm, 0.26 mm, 0.28 mm, 0.3 mm, 0.32 mm, 0.34 mm, 0.36 mm, 0.38 mm, 0.4 mm, etc.

[0204] When a is greater than or equal to 0.08 mm, the width of the slot opening 21435 of the slot section is large, which is conducive to timely cracking of the slot section when the battery cell 20 is depressurized, and is conducive to improving the timeliness of the battery cell 20. When a is less than or equal to 0.4 mm, the width of the slot opening 21435 of the slot section is not too large, which can reduce the risk of the slot section cracking due to the change of the internal gas pressure of the battery cell 20, and is conducive to improving the reliability of the battery cell 20. Therefore, when 0.08 mm≤a≤0.4 mm, the width of the slot opening 21435 of the slot section is moderate, the slot section is neither prone to cracking due to the change of the internal gas pressure of the battery cell 20, nor can timely cracking when the battery cell 20 is depressurized, which is conducive to improving the timeliness of the battery cell 20.

[0205] Optionally, 0.26 mm≤a≤0.34 mm.

[0206] The width of the slot opening 21435 of the slot section can be: a=0.26 mm, 0.27 mm, 0.28 mm, 0.29 mm, 0.3 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, etc.

[0207] When a is greater than or equal to 0.26 mm, the width of the slot opening 21435 of the slot section is larger, which is more conducive to timely cracking of the slot section when the battery cell 20 is depressurized, and is conducive to improving the timeliness of the battery cell 20. When a is less than or equal to 0.34 mm, the width of the slot opening 21435 of the slot section is not too large, which can reduce the risk of the slot section cracking due to the change of the internal gas pressure of the battery cell 20, and is conducive to improving the reliability of the battery cell 20. Therefore, when 0.26 mm≤a≤0.34 mm, the reliability and the timeliness of the battery cell 20 are better balanced.

[0208] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7 and FIG. 8, in some embodiments, the pressure relief structure 214 has a first surface 2111 and a second surface 2112 arranged opposite in the thickness direction of the wall portion 211, and the pressure relief structure 214 is provided with a plurality of levels of grooves arranged in sequence in the direction from the first surface 2111 to the second surface 2112. In two adjacent levels of grooves, the level of groove far from the first surface 2111 is arranged on the groove bottom surface 21431 of the level of groove close to the first surface 2111. Among them, the level of groove farthest from the first surface 2111 in the plurality of levels of grooves is the first groove 2143.

[0209] Along the thickness direction of the wall portion 211, the pressure relief structure 214 has a first surface 2111 and a second surface 2112 disposed opposite to each other. When the first surface 2111 is the surface of the pressure relief structure 214 facing away from the interior of the outer casing 21, the second surface 2112 is the surface of the pressure relief structure 214 facing the interior of the outer casing 21. When the first surface 2111 is the surface of the pressure relief structure 214 facing the interior of the outer casing 21, the second surface 2112 is the surface of the pressure relief structure 214 facing away from the interior of the outer casing 21.

[0210] The pressure relief structure 214 has multiple levels of grooves, which are sequentially arranged along the direction from the first surface 2111 to the second surface 2112. The contour of the bottom surface 21431 of the multiple levels of grooves decreases progressively. The cross-sectional shape of the grooves can be various, such as rectangular or circular. The grooves on the pressure relief structure 214 can be formed by various methods, such as stamping or cold heading.

[0211] The first groove 2143 is the groove furthest from the first surface 2111 in the multi-level groove.

[0212] For example, as shown in Figures 6 and 7, the pressure relief structure 214 has three levels of grooves: a first-level groove 2141, a second-level groove 2142, and a third-level groove. During processing, the first-level groove 2141 can be stamped onto the first surface 2111 firstly, then the second-level groove 2142 can be stamped onto the bottom surface 21431 of the first-level groove 2141, and finally the third-level groove can be stamped onto the bottom surface 21431 of the second-level groove 2142. In this case, the third-level groove is the one furthest from the first surface 2111 among the multiple levels of grooves; that is, the third-level groove is the first groove 2143.

[0213] Multi-level grooves are sequentially arranged on the pressure relief structure 214 along the direction from the first surface 2111 to the second surface 2112. During the molding process, multi-level grooves can be sequentially formed on the pressure relief structure 214 along the direction from the first surface 2111 to the second surface 2112.

[0214] Multi-level grooves are sequentially arranged on the pressure relief structure 214 along the direction from the first surface 2111 to the second surface 2112. During molding, the multi-level grooves can be formed step by step, thereby reducing the molding force on the pressure relief structure 214, reducing the risk of cracking, and making the pressure relief structure 214 less prone to failure due to cracks at the groove locations, thus improving the reliability of the battery cell 20. When forming the multi-level grooves, stamping or cold forging can be used, which causes work hardening of the groove walls (changing the grain arrangement, leading to lattice distortion, reducing metal plasticity, and increasing material hardness), enhancing its resistance to external impacts and making it less susceptible to damage from external impacts. This helps reduce the risk of leakage from the pressure relief structure 214.

[0215] In some embodiments, the first surface 2111 is a surface of the pressure relief structure 214 facing away from the inside of the shell 21.

[0216] The first surface 2111 is a surface of the pressure relief structure 214 facing away from the inside of the shell 21, i.e. the first surface 2111 is an outer surface of the pressure relief structure 214. At this time, the second surface 2112 is a surface of the pressure relief structure 214 facing the inside of the shell 21, i.e. the second surface 2112 is an inner surface of the pressure relief structure 214.

[0217] It should be noted that when the pressure relief structure 214 is integrally formed with the wall portion 211, the first surface 2111 is an outer surface of the wall portion 211, and the second surface 2112 is an inner surface of the wall portion 211.

[0218] By arranging the first groove 2143 on the surface of the pressure relief structure 214 facing away from the inside of the shell 21, the first weak portion is easier to crack when it needs to overcome a smaller tension.

[0219] In some embodiments, the first groove 2143 includes a plurality of groove segments, the plurality of groove segments are connected, and the plurality of groove segments collectively define at least one predetermined pressure relief area 21434. The predetermined pressure relief area 21434 is configured to be opened when the pressure relief structure 214 cracks along at least a portion of the first groove 2143, so as to release the internal pressure of the battery cell 20.

[0220] The first groove 2143 can include two groove segments, three groove segments, four groove segments, or more than four groove segments. The groove segments can be straight grooves extending along a straight line trajectory, or can be arc-shaped grooves extending along an arc trajectory.

[0221] The plurality of groove segments collectively define at least one predetermined pressure relief area 21434, and the first weak portion 2144 cracks along the edge of the predetermined pressure relief area 21434 when the battery cell 20 is relieved, so that the predetermined pressure relief area 21434 can be opened to relieve pressure.

[0222] The plurality of groove segments define the predetermined pressure relief area 21434, and the pressure relief structure 214 can crack along the plurality of groove segments to open the predetermined pressure relief area 21434 to release the pressure in the battery cell 20 when the battery cell 20 is relieved. Moreover, the connection position of the two groove segments is more weak and easier to crack and open the predetermined pressure relief area 21434 to relieve pressure, and can further improve the pressure relief area and the pressure relief rate of the battery cell 20.

[0223] Referring to FIG. 9, FIG. 9 is a bottom view of the casing 21 of the battery cell 20 according to some embodiments of the present application. In some embodiments, the plurality of groove segments includes a first groove segment 2143a and a second groove segment 2143b, the first groove segment 2143a is connected to the second groove segment 2143b, and the first groove segment 2143a and the second groove segment 2143b together define at least one predetermined pressure relief area 21434.

[0224] The line connecting the free end of the first groove segment 2143a and the free end of the second groove segment 2143b is a first line. The first groove segment 2143a, the second groove segment 2143b, and the first line together enclose a closed area, which is the predetermined pressure relief area 21434.

[0225] The first groove segment 2143a and the second groove segment 2143b together define the predetermined pressure relief area 21434. The first groove segment 2143a and the second groove segment 2143b are structures arranged along the edges of the predetermined pressure relief area 21434, so that when the battery cell 20 is relieved of pressure, the two weak segments can crack along the edges of the predetermined pressure relief area 21434.

[0226] For example, in FIG. 9, one end of the first groove segment 2143a is connected to one end of the second groove segment 2143b, so that the first groove segment 2143a and the second groove segment 2143b form a first groove 2143 of an "L" shaped structure. The first line connects the two ends of the "L" shaped structure. Of course, in other embodiments, one end of the second groove segment 2143b can also be connected to a middle position of the first groove segment 2143a, so that the pressure relief structure 214 forms a predetermined pressure relief area 21434 on both sides of the second groove segment 2143b.

[0227] The first groove segment 2143a and the second groove segment 2143b are connected structures, so that the first groove segment 2143a and the second groove segment 2143b together define at least one predetermined pressure relief area 21434. On the one hand, this can increase the pressure relief area of the battery cell 20, thereby increasing the pressure relief rate of the battery cell 20. On the other hand, the position where the first groove segment 2143a and the second groove segment 2143b are connected is weaker and more likely to crack and open the predetermined pressure relief area 21434 to release the internal pressure of the battery cell 20.

[0228] Referring to FIGS. 3, 4, 5, 6, 7, and 8, in some embodiments, the plurality of groove segments includes a first groove segment 2143a, a second groove segment 2143b, and a third groove segment 2143c, the first groove segment 2143a and the third groove segment 2143c are oppositely arranged, and the second groove segment 2143b connects the first groove segment 2143a and the third groove segment 2143c. The first groove segment 2143a, the second groove segment 2143b, and the third groove segment 2143c together define at least one predetermined pressure relief area 21434.

[0229] The first groove segment 2143a and the third groove segment 2143c are spaced apart and at least partially opposite. Optionally, the first groove segment 2143a and the third groove segment 2143c both extend along the width direction of the wall portion 211.

[0230] The second groove segment 2143b connects the first groove segment 2143a and the third groove segment 2143c, that is, the second groove segment 2143b is located between the first groove segment 2143a and the third groove segment 2143c, and the two ends of the second groove segment 2143b are connected to the first groove segment 2143a and the third groove segment 2143c respectively. Of course, in other embodiments, the two ends of the second groove segment 2143b can extend out of the first groove segment 2143a and the third groove segment 2143c respectively.

[0231] The first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c together define a predetermined pressure relief area 21434. Please refer to FIG. 5, the line connecting the free end of the first groove segment 2143a and the free end of the second groove segment 2143b is the first line, and the first line is arranged opposite to the second groove segment 2143b along the width direction of the wall portion 211. The closed area surrounded by the first groove segment 2143a, the second groove segment 2143b, the third groove segment 2143c and the first line is the predetermined pressure relief area 21434. That is, the first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c are structures arranged along the edges of the predetermined pressure relief area 21434, so that the predetermined pressure relief area 21434 can be opened with the first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c as boundaries, that is, the predetermined pressure relief area 21434 is formed in the area enclosed by the first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c, so that the part of the pressure relief structure 214 located in the predetermined pressure relief area 21434 can be opened with the first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c as boundaries when the battery monomer 20 is relieved, thereby releasing the internal pressure of the battery monomer 20.

[0232] In other embodiments, the first groove segment 2143a, the second groove segment 2143b and the third groove segment 2143c together form a first groove 2143 which can be a "U" shaped structure, that is, one end of the second groove segment 2143b is connected to one end of the first groove segment 2143a, and the other end is connected to one end of the third groove segment 2143c, to form a predetermined pressure relief area 21434 on the pressure relief structure 214. At this time, the first line closes the open end of the U-shaped structure.

[0233] The plurality of groove sections include a first groove section 2143a, a second groove section 2143b, and a third groove section 2143c, the second groove section 2143b connecting the first groove section 2143a and the third groove section 2143c, so that the pressure relief structure 214 can be broken along the first groove section 2143a, the second groove section 2143b, and the third groove section 2143c when the battery cell 20 is relieved of pressure, to open the predetermined pressure relief area 21434 to release the internal pressure of the battery cell 20, the connection positions of the first groove section 2143a and the second groove section 2143b and the connection positions of the first groove section 2143a and the third groove section 2143c being thinner and more easily broken to open the predetermined pressure relief area 21434 to relieve pressure, and further improving the pressure relief area and the pressure relief rate of the battery cell 20.

[0234] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, and FIG. 8, in some embodiments, the second groove section 2143b is connected to the first groove section 2143a at a position deviating from both ends of the first groove section 2143a, and the second groove section 2143b is connected to the third groove section 2143c at a position deviating from both ends of the third groove section 2143c, so that the predetermined pressure relief area 21434 is formed on both sides of the second groove section 2143b.

[0235] In the above embodiments, the connection position of the second groove section 2143b to the first groove section 2143a deviates from both ends of the first groove section 2143a, that is, the second groove section 2143b is connected between both ends of the first groove section 2143a, and similarly, the connection position of the third groove section 2143c to the second groove section 2143b deviates from both ends of the third groove section 2143c, that is, the second groove section 2143b is connected between both ends of the third groove section 2143c, so that the first groove 2143 formed by the first groove section 2143a, the second groove section 2143b, and the third groove section 2143c has a structure similar to an approximate "H" shape.

[0236] By setting the connection position of the first groove section 2143a to the second groove section 2143b to be between both ends of the first groove section 2143a, and setting the connection position of the third groove section 2143c to the second groove section 2143b to be between both ends of the third groove section 2143c, the first groove section 2143a, the second groove section 2143b, and the third groove section 2143c form a structure similar to an "H" shape, so that both sides of the second groove section 2143b of the first groove 2143 can form the predetermined pressure relief area 21434, and the two predetermined pressure relief areas 21434 can be opened in a split manner to relieve pressure when the battery cell 20 is relieved of pressure, which is beneficial to further increase the pressure relief effect of the battery cell 20 and effectively improve the pressure relief rate of the battery cell 20.

[0237] Please refer to FIG. 10, which is a bottom view of the shell 21 of the battery cell 20 according to some embodiments of the present application. In some embodiments, the first groove 2143 extends along an arc-shaped trajectory.

[0238] The arc-shaped trajectory can be a closed trajectory with two ends connected, in which case the first groove 2143 is a closed groove. For example, the first groove 2143 can be a circular groove, an elliptical groove, or the like. Please refer to FIG. 10, in the embodiment shown in FIG. 10, the first groove 2143 is in the shape of a racetrack. The arc-shaped trajectory can also be an unclosed trajectory with two ends not connected, in which case the first groove 2143 is an unclosed groove. For example, the first groove 2143 can be a C-shaped groove, a U-shaped groove, or the like.

[0239] By extending the first groove 2143 along the arc-shaped trajectory, the first groove 2143 can define a larger predetermined pressure relief area 21434, which opens a larger opening when the battery cell 20 is relieved of pressure, thereby facilitating the rapid relief of pressure of the battery cell 20.

[0240] In some embodiments, the pressure relief structure 214 is integrally formed with the wall portion 211.

[0241] Integrally formed means that the wall portion 211 and the pressure relief structure 214 are an integral structure when provided. For example, the pressure relief structure 214 can be formed on the wall portion 211 by stamping or cold heading, or the like.

[0242] Integrally forming the pressure relief structure 214 with the wall portion 211 eliminates the need for additional welding or bonding processes, which is conducive to reducing the risk of liquid leakage of the pressure relief structure 214. Moreover, during production, it is easy to make the initiation pressure of the processed plurality of battery cells 20 more consistent.

[0243] According to some embodiments of the present application, the material of the wall portion 211 includes a steel material.

[0244] For example, the material of the wall portion 211 can be carbon steel, alloy steel, or stainless steel, or the like.

[0245] It should be noted that the material of the wall portion 211 includes a steel material, if the wall portion 211 is an end cover 216 of the shell 21, then the material of the end cover 216 is a steel material; if the wall portion 211 is one wall of the shell 215, then the material of the shell 215 is a steel material.

[0246] In the present embodiment, by setting the material of the wall portion 211 to be a steel material, since steel has the characteristic of high strength, the wall portion 211 made of steel has better strength, so that under the condition that the burst pressure of the battery cell 20 is certain, the wall portion 211 can be made thinner, which is conducive to saving the space occupied by the wall portion 211.

[0247] In some embodiments, the steel material is carbon steel or stainless steel.

[0248] Exemplarily, the carbon steel can be low carbon steel, medium carbon steel or high carbon steel.

[0249] In the embodiment, the carbon steel or stainless steel is used as the material of the wall portion 211, which is low in cost and easy to manufacture.

[0250] In some embodiments, the material of the pressure relief structure 214 includes aluminum alloy.

[0251] It can be understood that, in the embodiment in which the pressure relief structure 214 is integrally formed with the wall portion 211, the material of the wall portion 211 includes aluminum alloy. If the wall portion 211 is the end cover 216, the end cover 216 can be made of aluminum alloy; if the wall portion 211 is the wall portion 211 in the shell 215, the shell 215 can be made of aluminum alloy.

[0252] The aluminum alloy has the characteristics of light weight and good ductility, and it is easier to process the first groove 2143 on the pressure relief structure 214. In the embodiment in which the pressure relief structure 214 is integrally formed with the wall portion 211, the wall portion 211 is made of aluminum alloy, which can effectively reduce the difficulty of forming the wall portion 211.

[0253] In some embodiments, the aluminum alloy includes the following components with the mass percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other single elements ≤ 0.03%.

[0254] This aluminum alloy belongs to three-system aluminum, and the aluminum alloy has lower hardness and better forming capacity, which reduces the processing difficulty of the first groove 2143 and is beneficial to improve the processing precision of the first groove 2143 and the pressure relief consistency of the pressure relief structure 214.

[0255] In some embodiments, the aluminum alloy includes the following components with the mass percentage: aluminum ≥ 96.7%, 0.05% ≤ copper ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other single element components ≤ 0.05%, and total other element components ≤ 0.15%.

[0256] This aluminum alloy belongs to five-system aluminum, and the pressure relief structure 214 made of this aluminum alloy has higher hardness and greater strength, and has good anti-damage capacity.

[0257] In other embodiments, the pressure relief structure 214 and the wall portion 211 are separately arranged, the wall portion 211 is provided with a pressure relief hole, and the pressure relief structure 214 is mounted on the wall portion 211 and covers the pressure relief hole.

[0258] The "pressure relief structure 214 is provided separately from the wall portion 211, the wall portion 211 is provided with a pressure relief hole, and the pressure relief structure 214 is mounted to the wall portion 211 and covers the pressure relief hole" means that, in manufacturing, the pressure relief hole is formed on the wall portion 211, the pressure relief structure 214 and the wall portion 211 are provided separately, and finally connected together. For example, the pressure relief structure 214 can be welded to the wall portion 211. The pressure relief structure 214 can be a rupture disc mounted to the wall portion 211.

[0259] By providing the pressure relief structure 214 separately from the wall portion 211 and mounting it to the wall portion 211, the manufacturing process is facilitated.

[0260] Referring to FIGS. 3, 4, 5, 6, 7, and 8, in some embodiments, the battery cell 20 includes an electrode assembly 22 housed within the housing 21. The wall portion 211 supports the electrode assembly 22 along the direction of gravity.

[0261] The wall portion 211 is a wall of the housing 21 that supports the electrode assembly 22 along the direction of gravity. It can be understood that the wall portion 211 can be a bottom wall of the casing 215. The wall portion 211 can also be an end cover 216. When the wall portion 211 is an end cover 216, it is a scenario in which the battery cell 20 is used upside down.

[0262] The wall portion 211 supports the electrode assembly 22 along the direction of gravity, and the pressure relief structure 214 is provided on the wall portion 211. In this way, when the battery cell 20 is pressure relieved, the ejected fluid medium is less likely to act on other electrical connection components, reducing the risk of short circuit when the battery cell 20 is pressure relieved.

[0263] Referring to FIGS. 3, 4, 5, 6, 7, and 8, in some embodiments, the battery cell 20 includes an electrode terminal 23 provided on a wall of the housing 21 other than the wall portion 211.

[0264] The electrode terminal 23 and the pressure relief structure 214 are provided on different walls of the housing 21. For example, when the wall portion 211 is a bottom wall of the casing 215, the electrode terminal 23 can be provided on a side wall 212 or an end cover 216 of the casing 215. For another example, when the wall portion 211 is a side wall 212 of the casing 215, the electrode terminal 23 can be provided on another side wall 212, a bottom wall, or an end cover 216 of the casing 215. When the wall portion 211 is an end cover 216, the electrode terminal 23 can be provided on a side wall 212 or a bottom wall of the casing 215.

[0265] The electrode terminal 23 and the pressure relief structure 214 are provided on different walls of the housing 21, respectively. In this way, when the battery cell 20 is pressure relieved, the ejected fluid medium is less likely to act on the electrode terminal 23 to cause the electrode terminal 23 to short circuit, reducing the risk of short circuit when the battery cell 20 is pressure relieved.

[0266] Optionally, the electrode terminal 23 is arranged on a wall of the housing 21 opposite to the wall portion 211.

[0267] When the wall portion 211 is a bottom wall of the shell 215, the electrode terminal 23 can be arranged on the end cover 216. When the wall portion 211 is one side wall 212 of the shell 215, the electrode terminal 23 can be arranged on another side wall 212 of the shell 215 opposite to the wall portion 211. When the wall portion 211 is the end cover 216, the electrode terminal 23 can be arranged on a bottom wall of the shell 215.

[0268] The electrode terminal 23 is arranged on a wall of the housing 21 opposite to the wall portion 211, and the electrode terminal 23 is far away from the pressure relief structure 214, so that the fluid medium sprayed when the battery monomer 20 is relieved of pressure is less likely to act on the electrode terminal 23 to cause the electrode terminal 23 to be short-circuited, further reducing the risk of short circuit when the battery monomer 20 is relieved of pressure.

[0269] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7 and FIG. 8, in some embodiments, the housing 21 includes a shell 215 and an end cover 216, the shell 215 has an opening 2151, and the end cover 216 is connected to the shell 215 and seals the opening 2151. Among them, the end cover 216 is the wall portion 211, or the shell 215 includes the wall portion 211.

[0270] The shell 215 includes an integrally formed side wall 212 and a bottom wall, that is, the shell 215 is processed by an integrally formed process, such as stamping, casting or extrusion molding, etc. Integrally formed process, that is, the side wall 212 and the bottom wall of the shell 215 are of an integral structure.

[0271] The shell 215 includes the wall portion 211, that is, the wall portion 211 is a wall of the shell 215. Exemplarily, in FIG. 5 and FIG. 6, the wall portion 211 is a bottom wall of the shell 215 arranged opposite to the end cover 216 in the thickness direction of the wall portion 211. Of course, in other embodiments, the wall portion 211 can also be a side wall 212 of the shell 215.

[0272] It should be noted that the structure of the battery monomer 20 is not limited to this, in some embodiments, the battery monomer 20 can also be other structures, for example, the housing 21 can include a shell 215 and an end cover 216, the shell 215 forms an accommodating cavity with an opening 2151 inside, the accommodating cavity is used to accommodate the electrode assembly 22, and the end cover 216 seals the opening 2151. The end cover 216 is the wall portion 211.

[0273] It should be noted that the structure of the battery cell 20 can also be various, in some embodiments, the shell 21 can include a shell body 215 and two end covers 216, the shell body 215 is internally formed with an accommodating cavity for accommodating the electrode assembly 22, the shell body 215 is formed with two openings 2151 at both ends in the thickness direction of the wall portion 211, and the two openings 2151 are in communication with the accommodating cavity, and the two end covers 216 respectively close the two openings 2151, and one of the two end covers 216 is the wall portion 211.

[0274] The shell body 215 of the shell 21 is provided with two openings 2151 at both ends in the thickness direction of the wall portion 211, and the two end covers 216 respectively close the two openings 2151, and the wall portion 211 is one of the two end covers 216, and the battery cell 20 with such a structure is convenient to assemble from both ends of the shell body 215, which is beneficial to reduce the manufacturing and assembly difficulty of the battery cell 20.

[0275] When the end cover 216 is the wall portion 211, the pressure relief structure 214 is arranged on the end cover 216, which is simple and convenient to manufacture. When the shell body 215 includes the wall portion 211, the pressure relief structure 214 is arranged on one wall of the shell body 215, and the fluid medium sprayed by the pressure relief structure 214 is not easy to act on other electrical connection structures on the end cover 216, which is beneficial to reduce the risk of short circuit of the battery cell 20.

[0276] The embodiments of the present application also provide a battery 100, which includes the battery cell 20 described above.

[0277] The embodiments of the present application also provide a use electric device, which includes the battery cell 20 described above.

[0278] According to some embodiments of the present application, please refer to FIGS. 3-8.

[0279] The battery monomer 20 provided by the embodiment of the application comprises an outer shell 21 and a pressure relief structure 214, the outer shell 21 has a wall portion 211, and the pressure relief structure 214 is arranged on the wall portion 211. The pressure relief structure 214 is provided with a first groove 2143, and the pressure relief structure 214 is configured to be capable of being split along at least a part of the first groove 2143 when the battery monomer 20 is relieved of pressure. The first groove 2143 comprises at least one groove segment, the groove segment comprises a groove bottom surface 21431 and two groove side surfaces 21432, the two groove side surfaces 21432 are oppositely arranged along the width direction of the groove segment, and the groove bottom surface 21431 and the at least one groove side surface 21432 are transitioned through a round corner 21433. The battery monomer 20 is provided with the pressure relief structure 214, the pressure relief structure 214 is provided with the first groove 2143, and the pressure relief structure 214 is capable of being split along at least a part of the first groove 2143 when the battery monomer 20 is relieved of pressure, thereby facilitating the relief of the pressure inside the battery monomer 20. The first groove 2143 comprises at least one groove segment, the groove segment comprises the groove bottom surface 21431 and the two groove side surfaces 21432 oppositely arranged along the width direction of the groove segment, and the groove bottom surface 21431 and the at least one groove side surface 21432 are transitioned through the round corner 21433, which is favorable for relieving the stress concentration of the groove segment, reducing the strain of the groove segment, and reducing the risk of early cracking of the first groove 2143, thereby being favorable for improving the service life of the battery monomer 20.

[0280] The radius of the round corner 21433 is r, and the width of the groove bottom surface 21431 is a, and 0.08≤r / a≤0.4 is satisfied. When r / a≥0.08, the radius of the round corner 21433 is relatively large, the effect of relieving the stress concentration of the groove segment is good, the strain of the groove segment can be effectively reduced, the risk of early cracking of the first groove 2143 is reduced, and the service life of the battery monomer 20 is improved. When r / a≤0.4, the radius of the round corner 21433 is not too large, and the stress concentration degree of the groove segment is not too small, thereby being favorable for the groove segment to be timely split when the battery monomer 20 is relieved of pressure, and being favorable for improving the timeliness of pressure relief of the battery monomer 20. Therefore, when 0.08≤r / a≤0.4, the service life of the battery monomer 20 and the timeliness of pressure relief of the battery monomer 20 can be considered.

[0281] Optionally, 0.12≤r / a≤0.3. When r / a≥0.12, the radius of the round corner 21433 is relatively larger, the effect of slowing down the stress concentration of the groove segment is better, the strain of the groove segment can be effectively reduced, the risk of the first groove 2143 cracking in advance is reduced, thereby helping to improve the service life of the battery monomer 20. When r / a≤0.3, the radius of the round corner 21433 is not too large, the stress concentration degree of the groove segment is not too small, thereby helping the groove segment to crack in time when the battery monomer 20 is pressure released, and helping to improve the timeliness of the pressure release of the battery monomer 20. Therefore, when 0.12≤r / a≤0.3, the service life of the battery monomer 20 and the timeliness of the pressure release of the battery monomer 20 can be better balanced.

[0282] In some embodiments, 0.03mm≤r≤0.15mm. When r≥0.03mm, the radius of the round corner 21433 is relatively larger, the effect of slowing down the stress concentration of the groove segment is better, the strain of the groove segment can be effectively reduced, the risk of the first groove 2143 cracking in advance is reduced, thereby helping to improve the service life of the battery monomer 20. When r≤0.15mm, the radius of the round corner 21433 is not too large, the stress concentration degree of the groove segment is not too small, thereby helping the groove segment to crack in time when the battery monomer 20 is pressure released, and helping to improve the timeliness of the pressure release of the battery monomer 20. Therefore, when 0.03mm≤r≤0.15mm, the service life of the battery monomer 20 and the timeliness of the pressure release of the battery monomer 20 can be better balanced.

[0283] Optionally, 0.06mm≤r≤0.1mm. When r≥0.06mm, the radius of the round corner 21433 is relatively larger, the effect of slowing down the stress concentration of the groove segment is better, the strain of the groove segment can be effectively reduced, the risk of the first groove 2143 cracking in advance is reduced, thereby helping to improve the service life of the battery monomer 20. When r≤0.1, the radius of the round corner 21433 is not too large, the stress concentration degree of the groove segment is not too small, thereby helping the groove segment to crack in time when the battery monomer 20 is pressure released, and helping to improve the timeliness of the pressure release of the battery monomer 20. Therefore, when 0.06mm≤r≤0.1mm, the service life of the battery monomer 20 and the timeliness of the pressure release of the battery monomer 20 can be better balanced.

[0284] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, wherein, include: The outer shell has walls; A pressure relief structure is disposed on the wall portion, the pressure relief structure is provided with a first groove, and the pressure relief structure is configured to be able to crack along at least a portion of the first groove when the battery cell is depressurized; The first groove includes at least one groove segment, the groove segment includes a groove bottom surface and two groove side surfaces, the two groove side surfaces are arranged opposite each other along the width direction of the groove segment, the groove bottom surface and at least one groove side surface are transitioned by a rounded corner, the radius of the rounded corner is r, and the width of the groove opening of the groove segment is a, satisfying: 0.08≤r / a≤0.

4.

2. The battery cell of claim 1, wherein, 0.12≤r / a≤0.3。 3. The battery cell of claim 1 or 2, wherein, 0.03mm≤r≤0.15mm.

4. The battery cell of claim 3, wherein, 0.06mm≤r≤0.1mm.

5. The battery cell of any one of claims 1-4, wherein, 0.08mm≤a≤0.4mm.

6. The battery cell of claim 5, wherein, 0.26mm≤a≤0.34mm.

7. The battery cell of any one of claims 1-6, wherein, The pressure relief structure has a first surface and a second surface that are disposed opposite to each other in the thickness direction of the wall portion. The pressure relief structure is provided with a multi-level groove arranged sequentially along the direction from the first surface to the second surface. In two adjacent levels of the groove, the first-level groove that is away from the first surface is disposed on the bottom surface of the first-level groove that is close to the first surface. Among them, the first groove is the one furthest from the first surface in the multi-level groove.

8. The battery cell of claim 7, wherein, The first surface is the surface of the pressure relief structure that faces away from the interior of the outer shell.

9. The battery cell of any one of claims 1-8, wherein, The first groove includes multiple connected segments that collectively define at least one predetermined pressure relief area. The predetermined pressure relief area is configured to be openable when the pressure relief structure splits along at least a portion of the first groove to release the internal pressure of the battery cell.

10. The battery cell of claim 9, wherein, The plurality of said slots include a first slot and a second slot, the first slot being connected to the second slot, and the first slot and the second slot together defining at least one of the predetermined pressure relief zones.

11. The battery cell of claim 9 or 10, wherein, The plurality of slot segments include a first slot segment, a second slot segment, and a third slot segment, the first slot segment and the third slot segment being disposed opposite to each other, the second slot segment connecting the first slot segment and the third slot segment, and the first slot segment, the second slot segment, and the third slot segment together defining at least one of the predetermined pressure relief zones.

12. The battery cell of claim 11, wherein, The second groove segment is connected to the first groove segment at a position offset from both ends of the first groove segment, and the second groove segment is connected to the third groove segment at a position offset from both ends of the third groove segment, so that the predetermined pressure relief zone is formed on both sides of the second groove segment.

13. The battery cell of any one of claims 1-12, wherein, The first groove extends along an arc-shaped trajectory.

14. The battery cell of any one of claims 1-13, wherein, The pressure relief structure is integrally formed with the wall portion.

15. The battery cell of any one of claims 1-13, wherein, The pressure relief structure is separately disposed from the wall portion, the wall portion is provided with a pressure relief hole, and the pressure relief structure is installed on the wall portion and covers the pressure relief hole.

16. The battery cell of any one of claims 1-15, wherein, The outer casing includes: The shell has an opening; End cap, connected to the housing and closing the opening; Wherein, the end cap is the wall portion, or the housing includes the wall portion.

17. A battery, wherein, Includes the battery cell according to any one of claims 1-16.

18. An electrical device, comprising: Includes the battery cell according to any one of claims 1-16.

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