Battery monomer, battery and electric equipment

Abstract

The embodiment of the utility model provides a battery monomer, a battery and electric equipment, and belongs to the technical field of batteries. Wherein the battery monomer comprises a shell and an electrode assembly. The housing includes a first wall portion. The electrode assembly is contained in the shell and comprises a first pole piece and a second pole piece which are opposite in polarity, and the first pole piece and the second pole piece are arranged in a stacked mode in the first direction. Wherein in the second direction, the first wall part faces the edge of the first pole piece and / or the edge of the second pole piece, the second direction intersects with the first direction, and the first wall part is provided with a pressure relief mechanism. When the single battery is in thermal runaway, a discharge medium generated between the first pole piece and the second pole piece can quickly flow to the pressure relief mechanism, so that the time for the discharge medium to reach the pressure relief mechanism is shortened, the pressure relief timeliness of the single battery is improved, and the reliability of the single battery is effectively improved.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority of Chinese patent application 2023103010199, entitled “Battery Cell, Battery and Electrical Equipment”, filed on March 24, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a battery cell, a battery and an electrical device. Background Art

[0004] Batteries are widely used in electronic devices, such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes and power tools, etc.

[0005] In battery technology, a pressure relief mechanism can be set in the battery cell to release pressure when the battery cell is in thermal runaway. For general battery cells, there is still a situation where pressure relief is not timely, and the reliability of the battery cell is poor. Therefore, how to improve the reliability of battery cells is a technical problem that needs to be solved urgently in battery technology. Utility Model Content

[0006] The embodiments of the present application provide a battery cell, a battery and an electrical device, which can effectively improve the reliability of the battery cell.

[0007] In a first aspect, an embodiment of the present application provides a battery cell, the battery cell comprising an outer shell and an electrode assembly; the outer shell comprises a first wall portion; the electrode assembly is accommodated in the outer shell, the electrode assembly comprises a first pole piece and a second pole piece with opposite polarities, the first pole piece and the second pole piece are stacked along a first direction; wherein, along the second direction, the first wall portion is arranged facing an edge of the first pole piece and / or an edge of the second pole piece, the second direction intersects with the first direction, and the first wall portion is provided with a pressure relief mechanism.

[0008] In the above technical solution, the first pole piece and the second pole piece are stacked along the first direction, so that the electrode assembly is a laminated electrode assembly. Since the first wall portion is arranged along the second direction facing the edge of the first pole piece and / or the edge of the second pole piece, and the pressure relief mechanism is arranged on the first wall portion, when the battery cell is thermally runaway, the discharge medium generated between the first pole piece and the second pole piece can quickly flow to the pressure relief mechanism, shortening the time for the discharge medium to reach the pressure relief mechanism, improving the timeliness of the pressure relief of the battery cell, and thus effectively improving the reliability of the battery cell.

[0009] In some embodiments, along the first direction, the thickness of the electrode assembly is T, and the width of the pressure relief region of the pressure relief mechanism is D, satisfying: D ≥ 1 / 3·T. In this way, the width of the pressure relief region is larger, and the pressure relief range of the pressure relief mechanism is increased, so that the discharge medium generated by more layers of pole pieces in the electrode assembly during thermal runaway can reach the pressure relief region more quickly, so that the battery cell can be depressurized more quickly during thermal runaway.

[0010] In some embodiments, D≥1 / 2·T. Further increasing the width of the pressure relief area further increases the pressure relief range of the pressure relief mechanism, thereby further improving the timeliness of the pressure relief of the battery cell.

[0011] In some embodiments, the housing has two first outer surfaces, the two first outer surfaces are arranged opposite to each other along a first direction, the first wall portion has a second outer surface, and the two first outer surfaces are connected to the second outer surface through a rounded surface; along the first direction, the distance between the two first outer surfaces is W, and the radius of the rounded surface is R, satisfying: D≤W-2·R. In this way, the pressure relief area of ​​the pressure relief mechanism is conducive to avoiding the corner area of ​​the corresponding rounded surface of the housing, reducing the difficulty of forming or installing the pressure relief mechanism.

[0012] In some embodiments, the electrode assembly further includes a separator, which is disposed between the first pole piece and the second pole piece, and the separator is configured to insulate and isolate the first pole piece and the second pole piece; along the first direction, the width of the pressure relief region of the pressure relief mechanism is D, and the thickness of the first pole piece is T 1 , the thickness of the second pole piece is T 2 , the thickness of the spacer is T 3 , the first electrode is a positive electrode, the number of layers of the first electrode in the electrode assembly is N, satisfying: D ≥ 1 / 3·N·(T 1 +T 2 +2·T 3 ). In this way, the width of the pressure relief area is larger, the pressure relief range of the pressure relief mechanism is increased, and the discharge medium generated by more layers of pole pieces in the electrode assembly during thermal runaway can reach the pressure relief area more quickly, so that the battery cell can be depressurized more quickly during thermal runaway.

[0013] In some embodiments, D≤4 / 3·N·(T 1 +T 2 +2·T 3 ). The pressure relief area of ​​the pressure relief mechanism is not too wide, which is conducive to the pressure relief area of ​​the pressure relief mechanism avoiding the corner area of ​​the shell, reducing the difficulty of forming or installing the pressure relief mechanism.

[0014] In some embodiments, N·(T 1 +T 2 +2·T 3 )≥D≥1 / 2·N·(T 1+T 2 +2·T 3 ). On the one hand, the pressure relief range of the pressure relief mechanism is further increased, and the timeliness of the pressure relief of the battery cell is further improved; on the other hand, the difficulty of molding or installing the pressure relief mechanism is further reduced.

[0015] In some embodiments, 75 μm ≤ T 1 ≤220μm; and / or, 80μm≤T 2 ≤250μm; and / or, 5μm≤T 3 ≤20μm.

[0016] In some embodiments, along the second direction, the projection of the electrode assembly completely covers the pressure relief region of the pressure relief mechanism, so that the pressure relief region can be opposite to more layers of pole pieces in the electrode assembly along the second direction, so that the discharge medium generated by more layers of pole pieces in the electrode assembly during thermal runaway can reach the pressure relief region more quickly.

[0017] In some embodiments, the battery cell further includes a first insulating member, and along the second direction, the first insulating member is at least partially disposed between the electrode assembly and the first wall portion, so as to achieve insulation isolation between the electrode assembly and the first wall portion, and reduce the probability of the electrode assembly contacting the first wall portion and causing an internal short circuit in the battery cell.

[0018] In some embodiments, the first insulating member is provided with a first discharge area, and the first discharge area is configured to allow the discharge medium inside the battery cell to move from the side of the first insulating member away from the pressure relief mechanism to the side of the first insulating member facing the pressure relief mechanism. The provision of the first discharge area can reduce the obstruction of the first insulating member on the discharge medium, so that the discharge medium generated by the electrode assembly can quickly reach the pressure relief mechanism through the first discharge area, thereby improving the timeliness of the pressure relief of the battery cell.

[0019] In some embodiments, the first discharge area includes a first through hole disposed on the first insulating member. Such a first discharge area has a simple structure and is easy to form. When the battery cell thermally runs away, the discharge medium generated by the electrode assembly can quickly reach the pressure relief mechanism through the first through hole.

[0020] In some embodiments, the battery cell further includes a support member, which is at least partially disposed between the first insulating member and the first wall portion along the second direction, and is configured to support the first insulating member and the electrode assembly. The support member can bear the gravity of the electrode assembly and the first insulating member, and can separate the first insulating member and the first wall portion, thereby reducing the influence of the electrode assembly and the first insulating member on the pressure relief mechanism and improving the life of the pressure relief mechanism.

[0021] In some embodiments, the support member is provided with a second discharge area, and the second discharge area is configured to allow the discharge medium inside the battery cell to move from the side of the support member away from the pressure relief mechanism to the side of the support member facing the pressure relief mechanism. The provision of the second discharge area can reduce the obstruction of the support member to the discharge medium, so that the discharge medium generated by the electrode assembly can quickly reach the pressure relief mechanism through the second discharge area, thereby improving the timeliness of the pressure relief of the battery cell.

[0022] In some embodiments, the second discharge area includes a second through hole disposed on the support member. Such a second discharge area has a simple structure and is easy to form. When the battery cell thermally runs away, the discharge medium generated by the electrode assembly can quickly reach the pressure relief mechanism through the second through hole.

[0023] In some embodiments, the first insulating member is wrapped around the electrode assembly. This achieves insulation between more areas of the electrode assembly and the housing, and improves the insulation performance between the electrode assembly and the housing. When assembling a battery cell, the first insulating member can be wrapped around the electrode assembly first, and then the first insulating member and the electrode assembly are installed in the housing as a whole, which can effectively reduce the difficulty of assembling the battery cell.

[0024] In some embodiments, the pressure relief mechanism is integrally formed with the first wall portion, so that the reliability of the pressure relief mechanism is higher, the connection process between the pressure relief mechanism and the first wall portion is omitted, and the production cost of the battery cell can be reduced.

[0025] In some embodiments, the inner surface and / or the outer surface of the first wall portion is provided with a groove, and the bottom wall of the groove forms a pressure relief mechanism. By providing a groove on the first wall portion to form an integrated pressure relief mechanism, the implementation method is simple and the production cost is low. In addition, when the outer surface of the first wall portion is provided with a groove, the groove can provide an escape space for the pressure relief mechanism to open, thereby reducing the probability that the pressure relief mechanism cannot be opened due to being blocked by external obstacles.

[0026] In some embodiments, the pressure relief mechanism is separately provided with the first wall portion, and the pressure relief mechanism is installed on the first wall portion. The pressure relief mechanism is a component independent of the housing, and the pressure relief mechanism and the housing can be produced and assembled separately, with low production difficulty and high efficiency.

[0027] In some embodiments, the pressure relief mechanism is provided with a notched groove, which defines a pressure relief area, and the pressure relief area is configured to open when the battery cell releases pressure. The area where the pressure relief mechanism is provided with the notched groove is weaker, and when the battery cell releases pressure, the pressure relief mechanism can be split along the notched groove, thereby opening the pressure relief area defined by the notched groove to achieve rapid pressure relief. The pressure relief mechanism of this structure has high sensitivity and good timeliness of pressure relief.

[0028] In some embodiments, the notched groove is a groove extending along a closed track. During the pressure relief process, after the pressure relief mechanism is split along the notched groove, the pressure relief area can be fully opened, thereby increasing the pressure relief area and improving the timeliness of the pressure relief of the battery cell.

[0029] In some embodiments, the housing includes a shell and an end cap, the shell has an opening, and the end cap closes the opening; wherein the first wall portion is formed on the shell. When assembling the battery cell, the electrode assembly can be loaded into the shell from the opening of the shell, and then the opening of the shell is closed by the end cap, so that the assembly of the battery cell is convenient and quick. Since the first wall portion forms the shell, the pressure relief mechanism is located on the shell, which reduces the probability that the discharge medium discharged from the battery cell when the pressure is relieved by the pressure relief mechanism affects the components outside the end cap.

[0030] In some embodiments, the housing includes a first wall portion, a second wall portion, a third wall portion, and a fourth wall portion, the first wall portion, the third wall portion, the second wall portion, and the fourth wall portion are connected end to end in sequence, the first wall portion and the second wall portion are arranged oppositely along the second direction, and the third wall portion and the fourth wall portion are arranged oppositely along the first direction. The housing is generally in the shape of a quadrangular prism, has a simple structure, and is easy to form.

[0031] In some embodiments, along the second direction, the distance between the first wall portion and the second wall portion is L 1 Along the first direction, the distance between the third wall portion and the fourth wall portion is L 2 , satisfying: L 2 <L 1 When the electrode assembly expands, the first wall and the second wall are less affected by the electrode assembly than the third wall and the fourth wall. Since the pressure relief mechanism is located on the first wall, the probability of the pressure relief mechanism being blocked or damaged by the expansion of the electrode assembly can be reduced.

[0032] In some embodiments, the shell is formed by bending a plate, and the first and second ends of the plate are connected to each other along the circumference of the opening. When forming the shell, it is only necessary to bend the plate and connect the first and second ends of the plate to each other. The shell forming method is simple and can effectively reduce the difficulty of forming the shell.

[0033] In some embodiments, along the circumference of the opening, the connection positions of the two ends are staggered with the first wall portion, so that the connection positions are not located on the first wall portion, reducing the influence of the connection positions on the pressure relief mechanism and improving the reliability of the pressure relief mechanism.

[0034] In some embodiments, the housing includes a second wall portion, and along the second direction, the first wall portion and the second wall portion are arranged opposite to each other, and the connection positions of the two ends are located on the second wall portion, so that the pressure relief mechanism and the connection position are respectively located on the opposite first wall portion and the second wall portion, and the pressure relief mechanism and the connection position are further apart in the circumferential direction of the opening, further reducing the influence of the connection position on the pressure relief mechanism.

[0035] In some embodiments, the housing is a rectangular parallelepiped housing, and an opening is formed at at least one end of the housing in the length direction. The housing of this structure is simple in structure and easy to shape.

[0036] In some embodiments, the length of the shell is a, the width of the shell is b, the height of the shell is c, and b≤c≤a / 1.5. The shell is in a long strip shape, which can meet the large capacity requirements of the battery cell.

[0037] In some embodiments, the electrode assembly includes a plurality of first pole pieces and a plurality of second pole pieces, and along the first direction, the first pole pieces and the second pole pieces are alternately arranged; along the second direction, the first wall portion is arranged facing the edge of the first pole piece and the edge of the second pole piece. In this way, the emissions generated by the first pole piece and the second pole piece when the battery cell is in thermal runaway can quickly reach the pressure relief mechanism, shortening the time for the emission medium to reach the pressure relief mechanism and improving the timeliness of the pressure relief of the battery cell.

[0038] In some embodiments, the electrode assembly includes a plurality of first pole pieces, the second pole piece includes a bent portion and a plurality of straight portions, two adjacent straight portions are connected by a bent portion, and along the first direction, the straight portions and the first pole pieces are alternately arranged; along the second direction, the first wall portion faces the edge of the first pole piece and the bent portion of the second pole piece. During molding, the plurality of first pole pieces can be arranged on both sides of the second pole piece, and then the second pole piece can be folded back and forth so that the second pole piece forms a straight portion and a bent portion, thereby realizing an alternating arrangement of the straight portion and the first pole piece, and the molding method of the electrode assembly is simple and the molding efficiency is high.

[0039] In some embodiments, the first wall portion is configured to support the electrode assembly, so that the pressure relief mechanism on the first wall portion is located at the bottom of the electrode assembly, which is conducive to the rapid discharge of the discharge medium inside the battery cell through the pressure relief mechanism by its own gravity.

[0040] In some embodiments, the first direction is perpendicular to the second direction.

[0041] In a second aspect, an embodiment of the present application provides a battery, comprising a battery cell provided by any embodiment of the first aspect.

[0042] In a third aspect, an embodiment of the present application provides an electrical device, comprising a battery cell provided by any one embodiment of the first aspect, wherein the battery cell is used to provide electrical energy to the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0045] Figure 2 An exploded view of a battery provided for some embodiments of the present application;

[0046] Figure 3 An axonometric view of a battery cell provided for some embodiments of the present application;

[0047] Figure 4 for Figure 3 An exploded view of a battery cell is shown;

[0048] Figure 5 for Figure 4 A schematic diagram of the structure of a battery cell shown;

[0049] Figure 6 for Figure 5 AA cross-sectional view of the battery cell shown;

[0050] Figure 7 for Figure 6 A partial enlarged view of the battery cell at position B is shown;

[0051] Figure 8 for Figure 7 A partial enlarged view of the battery cell at position C is shown;

[0052] Fig. 9 for Figure 8 A partial view of the electrode assembly shown;

[0053] Fig.10 A partial enlarged view of a battery cell provided in some other embodiments of the present application;

[0054] Fig.11 A schematic diagram of the structure of a battery cell provided in some other embodiments of the present application;

[0055] Fig.12 for Fig.11 DD cross-sectional view of the battery cell shown;

[0056] Fig.13 for Fig.12 A partial enlarged view of the battery cell at position E is shown;

[0057] Fig.14 for Fig.13 A partial enlarged view of the battery cell at F is shown;

[0058] Fig.15 A partial enlarged view of a battery cell provided in some other embodiments of the present application;

[0059] Fig.16 A partial view of a housing provided for some embodiments of the present application;

[0060] Fig.17 for Fig.16 A partial enlarged view of the housing at position G is shown;

[0061] Fig.18 A partial enlarged view of a housing provided in some other embodiments of the present application;

[0062] Fig.19 for Fig.18 A partial enlarged view of the housing at position J is shown;

[0063] Fig. 20 for Fig.16 I-direction view of the housing shown;

[0064] Fig.21 A schematic diagram of the structure of a housing provided in some embodiments of the present application;

[0065] Fig. 22 for Fig.21 An axonometric view of the housing shown;

[0066] Fig.23 for Fig. 22 A schematic diagram of the structure of the housing shown;

[0067] Fig.24 An axonometric view of a housing provided for some other embodiments of the present application;

[0068] Fig.25 for Fig.24 A schematic structural diagram of the housing shown;

[0069] Fig.26 for Fig.24 The schematic diagram of the structure of the shell after it is unfolded is shown;

[0070] Fig. 27 A schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application;

[0071] Fig.28 A schematic diagram of the structure of an electrode assembly provided in some other embodiments of the present application;

[0072] Fig.29 for Fig.28A partial enlarged view of the electrode assembly at K is shown.

[0073] Icons: 1-housing; 11-shell; 111-first wall; 1111-groove; 1112-pressure relief hole; 112-second wall; 1121-first end; 11211-first end surface; 1122-second end; 11221-second end surface; 1123-connection position; 113-third wall; 114-fourth wall; 115-first outer surface; 116-second outer surface; 117-rounded surface; 12-end cover; 2-electrode assembly; 21-ear; 22-first pole piece; 221-first edge; 23-second pole piece Two-electrode piece; 231-second edge; 232-bend portion; 233-straight portion; 24-isolator; 3-pressure relief mechanism; 31-pressure relief area; 32-notch groove; 4-electrode terminal; 5-first insulating member; 51-first discharge area; 6-second insulating member; 7-support member; 71-second discharge area; 10-battery cell; 20-housing; 201-first part; 202-second part; 100-battery; 200-controller; 300-motor; 1000-vehicle; X-first direction; Y-second direction; Z-third direction. DETAILED DESCRIPTION

[0074] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0075] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0076] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0077] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0078] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0079] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0080] The term "plurality" used in the present application refers to two or more (including two).

[0081] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0082] 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 storage battery, etc., which is not limited in the embodiments of the present application.

[0083] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0084] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0085] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0086] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc., treated with silver surface, may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may 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 substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0087] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 、LiMn2O 4 ), 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 O 2 (Also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O 2 (Also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O 2 (Also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (Also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn0.1 O 2 (Also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and at least one of its modified compounds.

[0088] In some embodiments, the positive electrode may be a foamed metal. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, or a carbon foam. When the foamed metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the foamed metal, but of course, the positive electrode active material may also be provided. As an example, a lithium source material, potassium metal or sodium metal may also be filled or / and deposited in the foamed metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0089] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0090] As an example, the negative electrode current collector can be a metal foil, a foamed metal or a composite current collector. For example, as a metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. can be used. The foamed metal can be a foamed nickel, a foamed copper, a foamed aluminum, a foamed alloy, or a foamed carbon, etc. The composite current collector can include a polymer material base 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 substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0091] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0092] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0093] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0094] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0095] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical stability and mechanical stability can be selected.

[0096] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without special restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without special restrictions. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surface of the positive and negative electrodes.

[0097] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0098] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. The electrolyte can be liquid, gel or solid.

[0099] The liquid electrolyte includes an electrolyte salt and a solvent.

[0100] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0101] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl 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, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent can also be selected from ether solvents. 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, methyltetrahydrofuran, diphenyl ether and crown ether.

[0102] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0103] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0104] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, and the like.

[0105] As an example, the inorganic solid electrolyte can be an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphosulfide, silver germanium sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0106] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0107] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0108] In some embodiments, the electrode assembly is a laminate structure.

[0109] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets may be alternately stacked.

[0110] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked straight portions, with one positive electrode sheet being sandwiched between adjacent straight portions.

[0111] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked straight portions.

[0112] As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0113] As an example, the separator may be disposed continuously, and may be disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0114] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0115] In some embodiments, the electrode assembly is provided with tabs, which can lead current out of the electrode assembly. The tabs include a positive tab and a negative tab.

[0116] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0117] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square shell battery cell, a blade-shaped battery cell, a polygonal battery, such as a hexagonal battery, etc. There is no special limitation in this application.

[0118] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0119] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0120] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are accommodated in the case.

[0121] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0122] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0123] The development of battery technology must take into account many design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery reliability must also be considered.

[0124] In battery technology, a pressure relief mechanism can be set in a battery cell to improve the reliability of the battery cell. The pressure relief mechanism on the battery cell has an important impact on the reliability of the battery. For example, when a short circuit or overcharge occurs, thermal runaway may occur inside the battery cell, causing a sudden increase in pressure or temperature. In this case, the pressure relief mechanism can release the internal pressure and temperature to the outside to reduce the probability of explosion or fire in the battery cell.

[0125] In a battery cell, a wound electrode assembly can be used, and the wound electrode assembly can be formed by winding a positive electrode sheet, a negative electrode sheet and a separator. The pressure relief mechanism of the battery cell is generally arranged on the wall of the shell parallel to the winding center line of the electrode assembly. For the wound electrode assembly, there are multiple layers of pole sheets in the direction perpendicular to the winding center line. When the battery cell is thermally runaway, the discharge medium generated inside the electrode assembly cannot pass through the pole sheets in the direction perpendicular to the winding center line to reach the pressure relief mechanism. The discharge medium can only be discharged from both ends of the electrode assembly in the direction of the winding center line, and then reach the pressure relief mechanism from the gap between the electrode assembly and the wall of the shell. This results in a longer path for the discharge medium to reach the pressure relief mechanism, and even the electrode assembly blocks the pressure relief mechanism. The discharge medium cannot reach the pressure relief mechanism in time, resulting in the battery cell being unable to release pressure in time, and the reliability of the battery cell is poor.

[0126] In view of this, an embodiment of the present application provides a battery cell, the battery cell comprising a housing and an electrode assembly. The housing comprises a first wall portion. The electrode assembly is accommodated in the housing, the electrode assembly comprises a first pole piece and a second pole piece with opposite polarities, the first pole piece and the second pole piece are stacked along a first direction; wherein, along a second direction, the first wall portion is arranged facing an edge of the first pole piece and / or an edge of the second pole piece, the second direction intersects with the first direction, and the first wall portion is provided with a pressure relief mechanism.

[0127] In such a battery cell, since the first wall portion is arranged along the second direction facing the edge of the first pole piece and / or the edge of the second pole piece, and the pressure relief mechanism is arranged on the first wall portion, when the battery cell thermally runs away, the discharge medium generated between the first pole piece and the second pole piece can flow quickly to the pressure relief mechanism, thereby shortening the time for the discharge medium to reach the pressure relief mechanism, improving the timeliness of the pressure relief of the battery cell, and thus effectively improving the reliability of the battery cell.

[0128] The technical solutions described in the embodiments of the present application are applicable to batteries and electrical equipment using batteries.

[0129] Electrical equipment may be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, electric tools, and the like. Vehicles may be fuel vehicles, gas vehicles, or new energy vehicles, and new energy vehicles may be pure electric vehicles, hybrid vehicles, or extended-range vehicles, and the like; spacecraft include airplanes, rockets, space shuttles, and spacecraft, and the like; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like; electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, and the like. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical equipment.

[0130] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0131] Please refer to Figure 1 , Figure 1 The schematic diagram of the structure of the vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 is provided with a battery 100 inside, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000, for example, the battery 100 can be used as an operating power source of the vehicle 1000.

[0132] The vehicle 1000 may further include a controller 200 and a motor 300 , wherein the controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, to meet the power requirements of starting, navigating, and driving the vehicle 1000 .

[0133] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0134] Please refer to Figure 2 , Figure 2 The exploded view of the battery 100 provided in some embodiments of the present application. The battery 100 includes a battery cell 10 and a box body 20, and the battery cell 10 is accommodated in the box body 20.

[0135] Among them, the box body 20 is a component for accommodating the battery cell 10. The box body 20 provides a storage space for the battery cell 10. The box body 20 can adopt a variety of structures. In some embodiments, the box body 20 may include a first part 201 and a second part 202, and the first part 201 and the second part 202 cover each other to define a storage space for accommodating the battery cell 10. The first part 201 and the second part 202 may be in a variety of shapes, such as a cuboid, a cylinder, etc. The first part 201 may be a hollow structure with one side open, and the second part 202 may also be a hollow structure with one side open, and the open side of the second part 202 covers the open side of the first part 201, so as to form a box body 20 with a storage space. It is also possible that the first part 201 is a hollow structure with one side open, and the second part 202 is a plate-like structure, and the second part 202 covers the open side of the first part 201, so as to form a box body 20 with a storage space. The first part 201 and the second part 202 can be sealed by a sealing element, and the sealing element can be a sealing ring, a sealant, etc.

[0136] In the battery 100, there may be one or more battery cells 10. If there are more than one battery cell 10, the battery cells 10 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the battery cells 10 are both connected in series and in parallel. The battery modules may be connected in series, in parallel, or in a mixed connection to form a battery module, and then the battery modules may be connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 20. Alternatively, all the battery cells 10 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by all the battery cells 10 may be accommodated in the box 20.

[0137] In some embodiments, the battery 100 may further include a busbar, through which multiple battery cells 10 may be electrically connected to achieve series connection, parallel connection, or hybrid connection of multiple battery cells 10. The busbar may be a metal conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0138] Please refer to Figure 3 and Figure 4 , Figure 3 An axonometric view of a battery cell 10 provided in some embodiments of the present application; Figure 4 for Figure 3 The exploded view of the battery cell 10 is shown. The battery cell 10 may include a housing 1, an electrode assembly 2 and a pressure relief mechanism 3.

[0139] The housing 1 is a component for accommodating the electrode assembly 2 and electrolyte, etc. As an example, the housing 1 may include a shell 11 and an end cap 12 .

[0140] The housing 11 may be a hollow structure with an opening at one end, or a hollow structure with openings at opposite ends. The housing 11 may be in various shapes, such as a cylindrical shape, a prism shape, etc. The housing 11 may be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc.

[0141] The end cap 12 is a component that closes the opening of the shell 11 to isolate the internal environment of the battery cell 10 from the external environment. The end cap 12 and the shell 11 together define a receiving space for accommodating the electrode assembly 2, the electrolyte and other components. The shape of the end cap 12 can be adapted to the shape of the shell 1. For example, the shell 11 is a rectangular parallelepiped structure, and the end cap 12 is a rectangular plate structure adapted to the shell 1. For another example, the shell 11 is a cylindrical structure, and the end cap 12 is a circular plate structure adapted to the shell 11. The material of the end cap 12 can also be a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. The material of the end cap 12 and the shell 11 can be the same or different.

[0142] In the embodiment where the housing 11 is opened at one end, one end cap 12 may be provided. In the embodiment where the housing 11 is opened at two opposite ends, two end caps 12 may be provided, and the two end caps 12 respectively close the two openings of the housing 11, and the two end caps 12 and the housing 11 together define a receiving space.

[0143] The pressure relief mechanism 3 is a component provided on the housing 1 for releasing the internal pressure of the battery cell 10. When the internal pressure of the battery cell 10 reaches a threshold, the discharge medium inside the battery cell 10 is discharged through the pressure relief mechanism 3 to achieve the purpose of pressure relief. The pressure relief mechanism 3 can be provided on the housing 11 or on the end cover 12. As an example, Figure 3 and Figure 4 In the embodiment, the pressure relief mechanism 3 is arranged on the housing 11 .

[0144] In some embodiments, the battery cell 10 may further include an electrode terminal 4, which is disposed on the housing 1 and is used to electrically connect to the tab 21 of the electrode assembly 2 to input or output the electrical energy of the battery cell 10. The electrode terminal 4 may be disposed on the shell 11 of the housing 1, or may be disposed on the end cover 12 of the housing 1. The electrode terminal 4 may be directly connected to the tab 21, for example, the electrode terminal 4 is directly welded to the tab 21. The electrode terminal 4 may also be indirectly connected to the tab 21, for example, the electrode terminal 4 is indirectly connected to the tab 21 through a current collecting member. The current collecting member may be a metal conductor, for example, copper, iron, aluminum, steel, aluminum alloy, etc.

[0145] As an example, Figure 4As shown, the shell 11 is a hollow structure with openings formed at opposite ends, and end covers 12 are provided at the opposite ends of the shell 11. Electrode terminals 4 are provided on the end covers 12 at both ends of the shell 11, and pole ears 21 are formed at the opposite ends of the electrode assembly 2. The pole ear 21 at one end of the electrode assembly 2 is a positive pole ear, and the pole ear 21 at the other end of the electrode assembly 2 is a negative pole ear. The electrode terminal 4 on one end cover 12 is electrically connected to the positive pole ear, and the electrode terminal 4 on the other end cover 12 is electrically connected to the negative pole ear.

[0146] In some embodiments, the battery cell 10 may further include a first insulating member 5, which is disposed between the electrode assembly 2 and the housing 11 and is used to insulate and isolate the electrode assembly 2 and the housing 11. The first insulating member 5 is made of insulating material, such as plastic, rubber, etc.

[0147] In some embodiments, the battery cell 10 may further include a second insulating member 6, which is disposed corresponding to the end cap 12, and is disposed on a side of the end cap 12 facing the electrode assembly 2, and is used to insulate and isolate the end cap 12 from the electrode assembly 2. The second insulating member 6 is made of an insulating material, such as plastic, rubber, etc.

[0148] Please refer to Figure 5 and Figure 6 , Figure 5 for Figure 4 The structural schematic diagram of the battery cell 10 shown; Figure 6 for Figure 5 AA cross-sectional view of the battery cell 10 shown. The embodiment of the present application provides a battery cell 10, and the battery cell 10 includes a shell 1 and an electrode assembly 2. The shell 1 includes a first wall portion 111. The electrode assembly 2 is accommodated in the shell 1, and the electrode assembly 2 includes a first pole piece 22 and a second pole piece 23 with opposite polarities, and the first pole piece 22 and the second pole piece 23 are stacked along the first direction X. Among them, along the second direction Y, the first wall portion 111 is arranged facing the edge of the first pole piece 22 and / or the edge of the second pole piece 23, the second direction Y intersects with the first direction X, and the first wall portion 111 is provided with a pressure relief mechanism 3.

[0149] The first wall portion 111 is a wall portion of the housing 1 on which the pressure relief mechanism 3 is disposed. The pressure relief mechanism 3 on the first wall portion 111 may be one or more. In the embodiment where the housing 1 includes a shell 11 and an end cover 12, the first wall portion 111 may be a wall portion of the housing 1, and the first wall portion 111 may also be the end cover 12. At least one wall portion of the shell 11 may be used as the first wall portion 111, and at least one end cover 12 may be used as the first wall portion 111.

[0150] The first electrode sheet 22 and the second electrode sheet 23 in the electrode assembly 2 are stacked, and the electrode assembly 2 is a laminated structure, that is, the electrode assembly 2 is a laminated electrode assembly 2. The first electrode sheet 22 may be a positive electrode sheet, and the second electrode sheet 23 may be a negative electrode sheet, or the first electrode sheet 22 may be a negative electrode sheet, and the second electrode sheet 23 may be a positive electrode sheet. Along the third direction Z, at least one end of the electrode assembly 2 is formed with a pole ear 21, and the pole ear 21 can be used to electrically connect to the electrode terminal 4 on the housing 1. As an example, along the third direction Z, pole ears 21 are formed at both ends of the electrode assembly 2, which are respectively a positive pole ear and a negative pole ear. The positive pole ear can be the portion of the positive pole sheet that is not coated with the positive active material layer, and the negative pole ear can be the portion of the negative pole sheet that is not coated with the negative active material layer.

[0151] The electrode assembly 2 may further include a separator 24 , which is disposed between the first electrode sheet 22 and the second electrode sheet 23 , and the separator 24 is configured to insulate and isolate the positive electrode sheet from the negative electrode sheet.

[0152] The first direction X is the stacking direction of the pole pieces in the electrode assembly 2, that is, the first direction X is the stacking direction of the first pole piece 22 and the second pole piece 23. In the electrode assembly 2, there may be multiple first pole pieces 22 and multiple second pole pieces 23, and the multiple first pole pieces 22 and multiple second pole pieces 23 are stacked along the first direction X; there may also be one first pole piece 22 and multiple second pole pieces 23, the first pole piece 22 is a folded structure, the first pole piece 22 is folded to form multiple straight portions, and the multiple straight portions and the multiple second pole pieces 23 are stacked along the first direction X; there may also be multiple first pole pieces 22 and one second pole piece 23, the second pole piece 23 is a folded structure, the second pole piece 23 is folded to form multiple straight portions, and the multiple straight portions and the multiple first pole pieces 22 are stacked along the first direction X.

[0153] Along the second direction Y, if the first wall portion 111 is arranged facing the edge of the first pole piece 22, the edge of the first pole piece 22 facing the first wall portion 111 can be defined as a first edge 221, and the first edge 221 is located at one end of the first pole piece 22 close to the first wall portion 111 along the second direction Y; if the first wall portion 111 is arranged facing the edge of the second pole piece 23, the edge of the second pole piece 23 facing the first wall portion 111 can be defined as a second edge 231, and the second edge 231 is located at one end of the second pole piece 23 close to the first wall portion 111 along the second direction Y. Figure 6 As shown, taking the example that there are multiple first pole pieces 22 and multiple second pole pieces 23 in the electrode assembly 2, and the multiple first pole pieces 22 and the multiple second pole pieces 23 are stacked along the first direction X, along the second direction Y, the first wall portion 111 is arranged facing the first edge 221 of the first pole piece 22 and the second edge 231 of the second pole piece 23.

[0154] The pressure relief mechanism 3 is a component in the battery cell 10 for releasing the pressure inside the battery cell 10. When the pressure inside the battery cell 10 reaches a threshold, the discharge medium inside the battery cell 10 is discharged through the pressure relief mechanism 3 to release the pressure inside the battery cell 10. The discharge medium includes, but is not limited to: electrolyte, dissolved or split positive and negative electrode sheets, fragments of the separator 24, gas generated by the reaction, etc.

[0155] The pressure relief mechanism 3 and the first wall portion 111 can be integrally formed; the pressure relief mechanism 3 and the first wall portion 111 can also be separately arranged, and the pressure relief mechanism 3 is installed on the first wall portion 111. For example, the pressure relief mechanism 3 is an explosion-proof disc, explosion-proof valve, safety valve, etc. installed on the first wall portion 111.

[0156] The angle between any two of the first direction X, the second direction Y and the third direction Z may be an acute angle or a right angle. As an example, the first direction X, the second direction Y and the third direction Z are perpendicular to each other.

[0157] In the embodiment of the present application, the first pole piece 22 and the second pole piece 23 are stacked along the first direction X, so that the electrode assembly 2 is a laminated electrode assembly 2. Since the first wall portion 111 is arranged along the second direction Y facing the edge of the first pole piece 22 and / or the edge of the second pole piece 23, and the pressure relief mechanism 3 is arranged on the first wall portion 111, when the battery cell 10 is thermally runaway, the discharge medium generated between the first pole piece 22 and the second pole piece 23 can quickly flow to the pressure relief mechanism 3, shortening the time for the discharge medium to reach the pressure relief mechanism 3, improving the timeliness of the pressure relief of the battery cell 10, and thus effectively improving the reliability of the battery cell 10.

[0158] In some embodiments, please refer to Figure 7-Figure 8 , Figure 7 for Figure 6 A partial enlarged view of the battery cell 10 at position B is shown; Figure 8 for Figure 7 The battery cell 10 is shown in a partially enlarged view at C. Along the first direction X, the thickness of the electrode assembly 2 is T, and the width of the pressure relief area 31 of the pressure relief mechanism 3 is D, satisfying: D≥1 / 3·T.

[0159] It can be understood that the thickness direction of the electrode assembly 2 and the width direction of the pressure relief area 31 of the pressure relief mechanism 3 are consistent with the first direction X.

[0160] The pressure relief area 31 is an area that can be opened when the pressure relief mechanism 3 is relieving pressure. The pressure relief area 31 may be a weak area in the pressure relief mechanism 3. For example, the pressure relief mechanism 3 is provided with a sink groove, and the area of ​​the pressure relief mechanism 3 corresponding to the sink groove is a weak area, and the weak area is the pressure relief area 31. The sink groove may be a rectangular groove, a circular groove, or an elliptical groove. A rectangular groove is a groove with a rectangular cross section, a circular groove is a groove with a circular cross section, and an elliptical groove is a groove with an elliptical cross section. The cross section referred to here is perpendicular to the depth direction of the sink groove. Figure 8 As shown, the pressure relief area 31 may also be an area defined by a weak area of ​​the pressure relief mechanism 3. For example, the pressure relief mechanism 3 is provided with a notched groove 32, and the area of ​​the pressure relief mechanism 3 corresponding to the notched groove 32 is a weak area. The notched groove 32 is located at the edge of the pressure relief area 31, and the notched groove 32 defines the pressure relief area 31.

[0161] It can be understood that D / T ≥ 1 / 3. D / T can be any point value among 1 / 3, 1 / 2, 3 / 5, 2 / 3, 1, 6 / 5, 4 / 3, etc., or a range of values ​​between any two points.

[0162] In this embodiment, D≥1 / 3·T, so that the width of the pressure relief area 31 is larger, and the pressure relief range of the pressure relief mechanism 3 is increased, so that the discharge medium generated by more layers of pole pieces in the electrode assembly 2 during thermal runaway can reach the pressure relief area 31 more quickly, so that the battery cell 10 can release pressure more quickly during thermal runaway.

[0163] In some embodiments, D ≥ 1 / 2·T.

[0164] It can be understood that D / T ≥ 1 / 2. D / T can be any point value among 1 / 2, 3 / 5, 2 / 3, 4 / 5, 1, 6 / 5, 4 / 3, etc., or a range of values ​​between any two points.

[0165] In this embodiment, D≥1 / 2·T, the width of the pressure relief area 31 is further increased, the pressure relief range of the pressure relief mechanism 3 is further increased, and the timeliness of the pressure relief of the battery cell 10 is further improved.

[0166] In some embodiments, please refer to Figure 7 The housing 1 has two first outer surfaces 115, the two first outer surfaces 115 are arranged opposite to each other along the first direction X, the first wall portion 111 has a second outer surface 116, and the two first outer surfaces 115 are connected to the second outer surface 116 through a rounded surface 117. Along the first direction X, the distance between the two first outer surfaces 115 is W, and the radius of the rounded surface 117 is R, satisfying: D≤W-2·R.

[0167] The two first outer surfaces 115 are outer surfaces of the housing 1 located on both sides along the first direction X. As an example, the housing 1 further includes a third wall portion 113 and a fourth wall portion 114 connected to the first wall portion 111, the third wall portion 113 and the fourth wall portion 114 are arranged opposite to each other along the first direction X, one first outer surface 115 is the outer surface of the third wall portion 113 away from the fourth wall portion 114, and the other first outer surface 115 is the outer surface of the fourth wall portion 114 away from the third wall portion 113. The distance W between the two first outer surfaces 115 along the first direction X is the size of the housing 1 in the first direction X. Taking the first direction X as the width direction of the housing 1 as an example, the distance W between the two first outer surfaces 115 along the first direction X is the width of the housing 1.

[0168] The cross section of the rounded surface 117 is in an arc shape, and the cross section is parallel to the first direction X and the second direction Y. As an example, the first outer surface 115 is perpendicular to the second outer surface 116, and the first outer surface 115 and the second outer surface 116 are both tangent to the rounded surface 117. The area of ​​the housing 1 corresponding to the rounded surface 117 is a corner area, the area where the first wall portion 111 and the third wall portion 113 are connected forms one corner area, and the area where the first wall portion 111 and the fourth wall portion 114 are connected forms another corner area.

[0169] In this embodiment, D≤W-2·R, which is conducive to the pressure relief area 31 of the pressure relief mechanism 3 avoiding the corner area of ​​the corresponding rounded surface 117 of the housing 1, thereby reducing the difficulty of forming or installing the pressure relief mechanism 3. For example, the pressure relief mechanism 3 and the first wall portion 111 are integrally formed, and the pressure relief mechanism 3 can be formed on the first wall portion 111 avoiding the corner area, thereby reducing the difficulty of forming the pressure relief mechanism 3; for another example, the pressure relief mechanism 3 and the first wall portion 111 are separately provided, and the pressure relief mechanism 3 can be installed on the first wall portion 111 avoiding the corner area, thereby reducing the difficulty of installing the pressure relief mechanism 3.

[0170] In some embodiments, please refer to Figure 8 and Fig. 9 , Fig. 9 for Figure 8 The electrode assembly 2 is a partial view shown in FIG. The electrode assembly 2 further includes a separator 24, which is disposed between the first pole piece 22 and the second pole piece 23. The separator 24 is configured to insulate and isolate the first pole piece 22 and the second pole piece 23. Along the first direction X, the width of the pressure relief region 31 of the pressure relief mechanism 3 is D, and the thickness of the first pole piece 22 is T. 1 , the thickness of the second pole piece 23 is T 2 , the thickness of the spacer 24 is T 3 , the first electrode sheet 22 is a positive electrode sheet, the number of layers of the first electrode sheet 22 in the electrode assembly 2 is N, and it satisfies: D ≥ 1 / 3·N·(T 1 +T 2 +2·T 3).

[0171] The isolation member 24 may be an isolation film disposed between the first pole piece 22 and the second pole piece 23 .

[0172] The thickness T of the first pole piece 22 1 That is, the thickness of the first electrode sheet 22 of each layer in the electrode assembly 2 along the first direction X; the thickness T of the second electrode sheet 23 2 That is, the thickness of each layer of the second electrode sheet 23 in the electrode assembly 2 along the first direction X; the thickness T of the isolation member 24 3 That is, the thickness of each layer of the separator 24 along the first direction X in the electrode assembly 2 .

[0173] In the electrode assembly 2, if there are multiple first pole pieces 22, for example, multiple first pole pieces 22 and multiple second pole pieces 23 are stacked, or for example, multiple first pole pieces 22 and multiple straight portions of the second pole pieces 23 are stacked, the number N of layers of the first pole pieces 22 in the electrode assembly 2 is the number of the first pole pieces 22; if there is one first pole piece 22 in the electrode assembly 2, the first pole piece 22 is folded to form multiple straight portions, and the multiple straight portions are stacked with multiple second pole pieces 23, the number N of layers of the first pole piece 22 in the electrode assembly 2 is the number of straight portions.

[0174] It is understandable that D / (N·(T 1 +T 2 +2·T 3 ))≥1 / 3. D / (N·(T 1 +T 2 +2·T 3 )) can be any point value among 1 / 3, 1 / 2, 3 / 5, 2 / 3, 1, 6 / 5, 4 / 3, etc. or a range of values ​​between any two points. N·(T 1 +T 2 +2·T 3 ) is substantially equal to the thickness of the electrode assembly 2 in the first direction X. As an example, 20≤N≤150.

[0175] The inventors conducted multiple groups of experiments, with different D in different groups, and measured the explosion rate of each group of battery cells 10 during thermal runaway. The test results are shown in Table 1 below.

[0176] The method for measuring the explosion rate of the battery cell 10 during thermal runaway is as follows: a small heating film is built into the battery cell 10, and the heating film is energized to heat the battery cell 10 until the battery cell 10 undergoes thermal runaway, and then observe whether the battery cell 10 explodes. Each group of experiments uses 1,000 battery cells 10, and the explosion rate of the battery cells 10 is calculated, where the explosion rate = the number of explosions / the total number × 100%.

[0177] Table 1

[0178]

[0179] In this embodiment, D / (N·(T 1 +T 2 +2·T 3 ))≥1 / 3, so that the width of the pressure relief area 31 is larger, the pressure relief range of the pressure relief mechanism 3 is increased, so that the discharge medium generated by more layers of pole pieces in the electrode assembly 2 during thermal runaway can reach the pressure relief area 31 more quickly, so that the battery cell 10 can release pressure more quickly during thermal runaway. It can be seen from Table 1 that when D / (N·(T 1 +T 2 +2·T 3 ))≥1 / 3, the explosion rate of the battery cell 10 during thermal runaway is low, and the pressure release timeliness of the battery cell 10 during thermal runaway is better.

[0180] In some embodiments, D≤4 / 3·N·(T 1 +T 2 +2·T 3 ).

[0181] It is understandable that D / (N·(T 1 +T 2 +2·T 3 ))≤4 / 3.

[0182] D / (N·(T 1 +T 2 +2·T 3 )) is too large, which may cause the pressure relief area 31 of the pressure relief mechanism 3 to be too wide, and the pressure relief mechanism 3 may be located in the corner area of ​​the housing 1. However, D / (N·(T 1 +T 2 +2·T 3 ))≤4 / 3, so that the pressure relief area 31 of the pressure relief mechanism 3 is not too wide, which is beneficial for the pressure relief area 31 of the pressure relief mechanism 3 to avoid the corner area of ​​the shell 1, thereby reducing the difficulty of molding or installing the pressure relief mechanism 3.

[0183] In some embodiments, N·(T 1 +T 2 +2·T 3 )≥D≥1 / 2·N·(T 1 +T 2 +2·T 3 ).

[0184] It is understandable that 1 / 2≤D / (N·(T 1 +T 2 +2·T 3 ))≤1.

[0185] D / (N·(T 1 +T 2 +2·T 3 )) can be any point value among 1 / 2, 3 / 5, 2 / 3, 7 / 10, 4 / 5, 9 / 10, 1, etc. or a range value between any two.

[0186] In this embodiment, 1 / 2≤D / (N·(T 1 +T 2 +2·T 3 ))≤1, on the one hand, the pressure relief range of the pressure relief mechanism 3 is further increased, and the timeliness of the pressure relief of the battery cell 10 is further improved; on the other hand, the difficulty of forming or installing the pressure relief mechanism 3 is further reduced.

[0187] In some embodiments, 75 μm ≤ T 1 ≤220μm; and / or, 80μm≤T 2 ≤250μm; and / or, 5μm≤T 3 ≤20μm.

[0188] T 1 It can be any point value among 75μm, 80μm, 100μm, 140μm, 160μm, 180μm, 200μm, 220μm, etc., or a range value between any two of them.

[0189] T 2 It can be any point value among 80μm, 100μm, 140μm, 160μm, 180μm, 200μm, 220μm, 230μm, 240μm, 250μm, etc., or a range value between any two of them.

[0190] T 3 It can be any point value among 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, etc., or a range value between any two of them.

[0191] In some embodiments, please refer to Figure 7-Figure 8 Along the second direction Y, the projection of the electrode assembly 2 completely covers the pressure relief area 31 of the pressure relief mechanism 3 .

[0192] It can be understood that, along the second direction Y, the projection of the pressure relief area 31 of the pressure relief mechanism 3 is completely located within the projection of the electrode assembly 2. Along the first direction X, the pressure relief area 31 of the pressure relief mechanism 3 does not exceed the electrode assembly 2.

[0193] As an example, along the first direction X, the pressure relief area 31 of the pressure relief mechanism 3 is arranged at the middle position of the first wall portion 111, and the electrode assembly 2 is arranged at the middle position of the shell 11, that is, the distance between the electrode assembly 2 and the third wall portion 113 is basically equal to the distance between the electrode assembly 2 and the fourth wall portion 114.

[0194] In this embodiment, the projection of the electrode assembly 2 along the second direction Y completely covers the pressure relief area 31 of the pressure relief mechanism 3, so that the pressure relief area 31 can be opposite to more layers of pole pieces in the electrode assembly 2 along the second direction Y, so that the discharge medium generated by more layers of pole pieces in the electrode assembly 2 during thermal runaway can reach the pressure relief area 31 more quickly.

[0195] In some embodiments, please refer to Figure 7 and Figure 8 The battery cell 10 further includes a first insulating member 5 . Along the second direction Y, the first insulating member 5 is at least partially disposed between the electrode assembly 2 and the first wall portion 111 .

[0196] The first insulating member 5 may be partially located between the electrode assembly 2 and the first wall portion 111, for example, the first insulating member 5 is wrapped around the electrode assembly 2, and the first insulating member 5 is partially located between the electrode assembly 2 and the first wall portion 111. The first insulating member 5 may also be completely located between the electrode assembly 2 and the first wall portion 111, for example, the first insulating member 5 is a flat plate structure disposed between the electrode assembly 2 and the first wall portion 111.

[0197] When the battery cell 10 is in thermal runaway, the discharge medium generated between the first pole piece 22 and the second pole piece 23 is in a high temperature state, and the discharge medium can flow to the pressure relief mechanism 3 after destroying or melting the first insulating member 5 .

[0198] In this embodiment, the first insulating member 5 at least achieves insulation isolation between the electrode assembly 2 and the first wall portion 111 , thereby reducing the probability of the electrode assembly 2 contacting the first wall portion 111 and causing an internal short circuit in the battery cell 10 .

[0199] In some embodiments, please refer to Fig.10 , Fig.10 Partially enlarged views of battery cells 10 provided in other embodiments of the present application. The first insulating member 5 is provided with a first discharge area 51, and the first discharge area 51 is configured to allow the discharge medium inside the battery cell 10 to move from the side of the first insulating member 5 away from the pressure relief mechanism 3 to the side of the first insulating member 5 facing the pressure relief mechanism 3.

[0200] The first discharge area 51 is provided on the portion of the first insulating member 5 between the first wall portion 111 and the electrode assembly 2, and the first discharge area 51 may be of various structures. For example, the first discharge area 51 is a through hole provided on the first insulating member 5. For another example, a first weak portion is formed on the first insulating member 5, and the first weak portion defines the first discharge area 51. When the battery cell 10 is in thermal runaway, the discharge medium causes the first insulating member 5 to rupture from the first weak portion, thereby opening the first discharge area 51 and forming a through hole in the opened area. The first weak portion may be formed by providing a groove, a broken line, etc. on the first insulating member 5.

[0201] As an example, along the second direction Y, the projection of the first discharge area 51 at least partially overlaps with the projection of the pressure relief region 31 of the pressure relief mechanism 3. In this way, the time for the discharge generated between the pole pieces to reach the pressure relief mechanism 3 can be further shortened.

[0202] In this embodiment, the provision of the first discharge area 51 can reduce the obstruction of the first insulating member 5 on the discharge medium, so that the discharge medium generated by the electrode assembly 2 can quickly reach the pressure relief mechanism 3 through the first discharge area 51, thereby improving the timeliness of the pressure relief of the battery cell 10.

[0203] In some embodiments, please refer to Fig.10 The first discharge area 51 includes a first through hole provided on the first insulating member 5 .

[0204] Along the second direction Y, the first through hole penetrates the portion of the first insulating member 5 between the first wall portion 111 and the electrode assembly 2. The first through hole on the first insulating member 5 may be one or more.

[0205] In this embodiment, the first discharge area 51 has a simple structure and is easy to form. When the battery cell 10 is in thermal runaway, the discharge medium generated by the electrode assembly 2 can quickly reach the pressure relief mechanism 3 through the first through hole.

[0206] In some embodiments, please refer to Figure 11-Figure 14 , Fig.11 A schematic diagram of the structure of a battery cell 10 provided in some other embodiments of the present application; Fig.12 for Fig.11 DD cross-sectional view of the battery cell 10 shown;

[0207] Fig.13 for Fig.12 A partial enlarged view of the battery cell 10 at position E is shown; Fig.14 for Fig.13The battery cell 10 is shown as a partial enlarged view at F. The battery cell 10 further includes a support member 7 , which is at least partially disposed between the first insulating member 5 and the first wall portion 111 along the second direction Y, and is configured to support the first insulating member 5 and the electrode assembly 2 .

[0208] The support member 7 is a component disposed between the first insulating member 5 and the first wall portion 111 and supporting the first insulating member 5 and the electrode assembly 2. The support member 7 can bear the weight of the first insulating member 5 and the electrode assembly 2, and the weight of the first insulating member 5 and the electrode assembly 2 can be transmitted to the first wall portion 111 through the support member 7. The support member 7 can be partially located between the first insulating member 5 and the first wall portion 111, or can be completely located between the first insulating member 5 and the first wall portion 111. The support member 7 can be a flat plate structure disposed between the first insulating member 5 and the first wall portion 111. The support member 7 can also be made of metal, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc. The support member 7 can also be made of insulating material, such as rubber, plastic, etc., to improve the insulation performance between the electrode assembly 2 and the first wall portion 111.

[0209] It should be noted that, in this embodiment, the first insulating member 5 may be provided with the first discharge area 51, or may not be provided with the first discharge area 51. Fig.14 As shown, taking the example that the first discharge area 51 is not provided on the first insulating member 5, when the battery cell 10 is thermally runaway, the discharge medium generated between the first pole piece 22 and the second pole piece 23 is in a high temperature state, and the discharge medium can flow to the pressure relief mechanism 3 after destroying or melting the first insulating member 5 and the support member 7.

[0210] In this embodiment, the support member 7 can bear the gravity of the electrode assembly 2 and the first insulating member 5, and can separate the first insulating member 5 and the first wall portion 111, thereby reducing the impact of the electrode assembly 2 and the first insulating member 5 on the pressure relief mechanism 3 and increasing the life of the pressure relief mechanism 3.

[0211] In some embodiments, please refer to Fig.15 , Fig.15 The support member 7 is provided with a second discharge area 71, which is configured to allow the discharge medium inside the battery cell 10 to move from the side of the support member 7 away from the pressure relief mechanism 3 to the side of the support member 7 facing the pressure relief mechanism 3.

[0212] The second discharge area 71 can be a variety of structures. For example, the second discharge area 71 is a through hole set on the support member 7; for another example, a second weak portion is formed on the support member 7, and the second weak portion defines the second discharge area 71. When the battery cell 10 is thermally runaway, the discharge medium causes the support member 7 to rupture from the second weak portion, thereby opening the second discharge area 71 and forming a through hole in the opened area. The second weak portion can be formed by providing a groove, a breaking line, etc. on the support member 7.

[0213] As an example, a first discharge area 51 is provided on the first insulating member 5, and a second discharge area 71 on the support member 7 is provided corresponding to the first discharge area 51 on the first insulating member 5. Along the second direction Y, a projection of the first discharge area 51 at least partially overlaps a projection of the pressure relief area 31 of the pressure relief mechanism 3.

[0214] In this embodiment, the provision of the second discharge area 71 can reduce the obstruction of the support member 7 on the discharge medium, so that the discharge medium generated by the electrode assembly 2 can quickly reach the pressure relief mechanism 3 through the second discharge area 71, thereby improving the timeliness of the pressure relief of the battery cell 10.

[0215] In some embodiments, please refer to Fig.15 The second discharge area 71 includes a second through hole arranged on the support member 7.

[0216] The second through hole penetrates the support member 7 along the second direction Y. The number of the second through hole on the support member 7 can be one or more.

[0217] As an example, the first discharge area 51 includes a first through hole disposed on the first insulating member 5, and along the second direction Y, a projection of the first through hole at least partially overlaps with a projection of the second through hole. Fig.15 In the embodiment, the aperture of the first through hole is equal to the aperture of the second through hole, and the center line of the first through hole coincides with the center line of the second through hole, so that the projection of the first through hole along the second direction Y completely overlaps with the projection of the second through hole along the second direction Y.

[0218] In this embodiment, the second discharge area 71 has a simple structure and is easy to form. When the battery cell 10 is in thermal runaway, the discharge medium generated by the electrode assembly 2 can quickly reach the pressure relief mechanism 3 through the second through hole.

[0219] In some embodiments, please refer to Figure 11-13 , the first insulating member 5 is wrapped around the electrode assembly 2 .

[0220] As an example, the first insulating member 5 is wrapped around the electrode assembly 2 around a center line extending along the third direction Z. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0221] In this embodiment, the first insulating member 5 is wrapped around the electrode assembly 2 to achieve insulation of more areas of the electrode assembly 2 and the housing 1, thereby improving the insulation performance between the electrode assembly 2 and the housing 1. When assembling the battery cell 10, the first insulating member 5 can be wrapped around the electrode assembly 2 first, and then the first insulating member 5 and the electrode assembly 2 are installed in the housing 1 as a whole, which can effectively reduce the difficulty of assembling the battery cell 10.

[0222] In some embodiments, please refer to Fig.16 and Fig.17 , Fig.16 A partial view of a housing 1 provided for some embodiments of the present application; Fig.17 for Fig.16 The housing 1 is shown in a partially enlarged view at G. The pressure relief mechanism 3 is integrally formed with the first wall portion 111. In this way, the pressure relief mechanism 3 has a higher reliability, the connection process between the pressure relief mechanism 3 and the first wall portion 111 is omitted, and the production cost of the battery cell 10 can be reduced.

[0223] In some embodiments, please refer to Fig.16 and Fig.17 The inner surface and / or outer surface of the first wall portion 111 is provided with a groove 1111 , and the bottom wall of the groove 1111 forms a pressure relief mechanism 3 .

[0224] The inner surface of the first wall portion 111 faces the inside of the housing 1, and the outer surface of the first wall portion 111 faces the outside of the housing 1. The inner surface of the first wall portion 111 may be provided with the groove 1111, and the outer surface of the first wall portion 111 may not be provided with the groove 1111, and the portion of the first wall portion 111 between the bottom surface of the groove 1111 and the outer surface of the first wall portion 111 is the groove bottom wall of the groove 1111. The inner surface of the first wall portion 111 may not be provided with the groove 1111, and the outer surface of the first wall portion 111 may be provided with the groove 1111, and the portion of the first wall portion 111 between the bottom surface of the groove 1111 and the inner surface of the first wall portion 111 is the groove bottom wall of the groove 1111. The inner surface and the outer surface of the first wall portion 111 may be both provided with grooves 1111, and the portion of the first wall portion 111 located between the bottom surfaces of the two grooves 1111 is the bottom wall of the groove 1111. It can be understood that the groove 1111 provided on the inner surface of the first wall portion 111 and the groove 1111 provided on the outer surface of the first wall portion 111 share a bottom wall.

[0225] The first wall portion 111 is thinner in a region where the groove 1111 is provided, and the region forms a pressure relief mechanism 3 integrally formed with the first wall portion 111 .

[0226] The groove 1111 can be formed in the first wall portion 111 in a variety of ways, such as stamping, milling, and laser etching. The groove 1111 can be a groove of various shapes, such as a rectangular groove, a circular groove, or an elliptical groove. A rectangular groove is a groove with a rectangular cross section, a circular groove is a groove with a circular cross section, and an elliptical groove is a groove with an elliptical cross section, where the cross section is perpendicular to the depth direction of the groove 1111.

[0227] The integrated pressure relief mechanism 3 is formed by providing the groove 1111 on the first wall portion 111, which is simple to implement and has low production cost. In addition, when the outer surface of the first wall portion 111 is provided with the groove 1111, the groove 1111 can provide an escape space for the pressure relief mechanism 3 to open, thereby reducing the probability that the pressure relief mechanism 3 cannot be opened due to being blocked by external obstacles.

[0228] In some embodiments, please refer to Fig.18 and Fig.19 , Fig.18 A partial enlarged view of the housing 1 provided in some other embodiments of the present application; Fig.19 for Fig.18 The illustrated partial enlarged view of the housing 1 at position J. The pressure relief mechanism 3 is disposed separately from the first wall portion 111 , and the pressure relief mechanism 3 is installed on the first wall portion 111 .

[0229] The pressure relief mechanism 3 and the housing 1 are two separate components, which are separately molded and then installed together. The pressure relief mechanism 3 can be a component such as an explosion-proof plate, an explosion-proof valve, or a safety valve. The pressure relief mechanism 3 can be installed on the first wall portion 111 by bonding, welding, or the like. The first wall portion 111 is provided with a pressure relief hole 1112, and the pressure relief mechanism 3 is installed in the pressure relief hole 1112. When the internal pressure of the battery cell 10 reaches a threshold value, the pressure relief mechanism 3 opens at least part of the pressure relief hole 1112, and the discharge medium inside the battery cell 10 is discharged through the pressure relief hole 1112 to release the pressure inside the battery cell 10.

[0230] like Fig.19 As shown, taking the pressure relief mechanism 3 as an explosion-proof disc as an example, the explosion-proof disc is a disc body whose strength in at least a part of the area is less than that of the first wall portion 111, and the explosion-proof disc covers the pressure relief hole 1112, and the explosion-proof disc is welded to the first wall portion 111. When the internal pressure of the battery cell 10 reaches a threshold value, the explosion-proof disc is at least partially destroyed, thereby opening at least a part of the pressure relief hole 1112 to release the pressure inside the battery cell 10.

[0231] In this embodiment, the pressure relief mechanism 3 is a component independent of the housing 1 , and the pressure relief mechanism 3 and the housing 1 can be produced and reassembled separately, with low production difficulty and high efficiency.

[0232] In some embodiments, please refer to Fig.17 and Fig.19 The pressure relief mechanism 3 is provided with a notched groove 32 , which defines a pressure relief area 31 , and the pressure relief area 31 is configured to open when the battery cell 10 is depressurized.

[0233] The notched groove 32 can be arranged on the surface of the pressure relief mechanism 3 facing the inside of the housing 1, or on the surface of the pressure relief mechanism 3 facing away from the inside of the housing 1. The notched groove 32 defines the pressure relief area 31, and the notched groove 32 is located at the edge of the pressure relief area 31. The notched groove 32 can be formed in a variety of ways, such as stamping, milling, and laser etching. The notched groove 32 can extend along a closed trajectory; the notched groove 32 can also extend along a non-closed trajectory, for example, the notched groove 32 is a groove extending along a circular arc, a U-shaped trajectory, or the like.

[0234] like Fig.17 As shown, in the embodiment where the pressure relief mechanism 3 and the first wall portion 111 are integrally formed, the pressure relief area 31 and the notched groove 32 are both located on the bottom wall of the groove 1111 .

[0235] In this embodiment, the pressure relief mechanism 3 is provided with a notch groove 32, and the area where the pressure relief mechanism 3 is provided with the notch groove 32 is weaker. When the battery cell 10 is depressurized, the pressure relief mechanism 3 can be split along the notch groove 32, thereby opening the pressure relief area 31 defined by the notch groove 32, thereby achieving rapid pressure relief. The pressure relief mechanism 3 of this structure has high sensitivity and good timeliness of pressure relief.

[0236] In some embodiments, please refer to Fig. 20 , Fig. 20 for Fig.16 The I-direction view of the housing 1 is shown. The notched groove 32 is a groove extending along a closed track.

[0237] The notched groove 32 is an annular groove, which can be a rectangular annular groove or a circular annular groove. A rectangular annular groove is a groove extending along a rectangular track, and a circular annular groove is a groove extending along a circular track. Fig. 20 In the illustrated embodiment, the score groove 32 is a generally rectangular annular groove.

[0238] During the pressure relief process, after the pressure relief mechanism 3 is split along the notched groove 32 , the pressure relief region 31 can be fully opened, thereby increasing the pressure relief area and improving the timeliness of the pressure relief of the battery cell 10 .

[0239] In some embodiments, please refer to Fig.21 , Fig.21 The schematic diagram of the structure of the housing 1 provided in some embodiments of the present application is as follows. The housing 1 comprises a shell 11 and an end cover 12, wherein the shell 11 has an opening and the end cover 12 closes the opening. The first wall portion 111 is formed on the shell 11.

[0240] The housing 11 may have an opening at one end or at both opposite ends. Fig.21 As shown, along the third direction Z, openings are formed at both opposite ends of the housing 11 , and the first direction X, the second direction Y and the third direction Z may be perpendicular to each other.

[0241] The shell 11 may be prism-shaped, such as a quadrangular prism, a hexagonal prism, etc. The quadrangular prism shell 11 may be a rectangular parallelepiped shell, a cube shell, etc. The end cap 12 corresponds to the opening of the shell 11 one by one, and the end cap 12 may be connected to the shell 11 in a variety of ways, such as the end cap 12 may be connected to the shell 11 by welding or crimping to close the opening of the shell 11. The end cap 12 may be provided with an electrode terminal 4 for electrically connecting to the electrode assembly 2 to input or output the electrical energy of the battery cell 10.

[0242] When assembling the battery cell 10, the electrode assembly 2 can be loaded into the shell 11 from the opening of the shell 11, and then the opening of the shell 11 is closed by the end cover 12, so that the assembly of the battery cell 10 is convenient and quick. Since the first wall portion 111 forms the shell 11, the pressure relief mechanism 3 is located on the shell 11, which reduces the probability that the discharge medium discharged when the battery cell 10 is depressurized by the pressure relief mechanism 3 affects the components outside the end cover 12. The component can be a busbar component, a detection component, etc. that is electrically connected to the electrode terminal 4 on the end cover 12. The detection component can be a component for obtaining signals such as current, voltage, and temperature of the battery cell 10.

[0243] In some embodiments, please refer to Fig. 22 , Fig. 22 for Fig.21 The isometric view of the housing 11 is shown. The housing 11 includes a first wall portion 111, a second wall portion 112, a third wall portion 113 and a fourth wall portion 114, which are connected end to end in sequence, and the first wall portion 111 and the second wall portion 112 are arranged opposite to each other along the second direction Y, and the third wall portion 113 and the fourth wall portion 114 are arranged opposite to each other along the first direction X.

[0244] The second direction Y may be perpendicular to the first wall portion 111 and the second wall portion 112, and the first direction X may be perpendicular to the third wall portion 113 and the fourth wall portion 114. The first wall portion 111, the second wall portion 112, the third wall portion 113, and the fourth wall portion 114 may be located at four sides of a parallelogram, respectively. As an example, in the first wall portion 111, the second wall portion 112, the third wall portion 113, and the fourth wall portion 114, two adjacent wall portions are vertically arranged.

[0245] In this embodiment, the housing 11 is substantially in the shape of a quadrangular prism, has a simple structure, and is easy to shape.

[0246] In some embodiments, please refer to Fig.23 , Fig.23 for Fig. 22 The schematic diagram of the structure of the housing 11 is shown in FIG. Along the second direction Y, the distance between the first wall portion 111 and the second wall portion 112 is L 1 Along the first direction X, the distance between the third wall portion 113 and the fourth wall portion 114 is L 2 , satisfying: L 2 <L 1 .

[0247] Along the second direction Y, the distance between the first wall portion 111 and the second wall portion 112 is the distance between the inner surface of the first wall portion 111 and the inner surface of the second wall portion 112. Along the first direction X, the distance between the third wall portion 113 and the fourth wall portion 114 is the distance between the inner surface of the third wall portion 113 and the inner surface of the fourth wall portion 114.

[0248] In this embodiment, L 2 <L 1 When the electrode assembly 2 expands, the first wall portion 111 and the second wall portion 112 are less affected by the electrode assembly 2 than the third wall portion 113 and the fourth wall portion 114. Since the pressure relief mechanism 3 is located in the first wall portion 111, the probability of the pressure relief mechanism 3 being blocked or damaged by the expansion of the electrode assembly 2 can be reduced.

[0249] In some embodiments, please refer to Figure 24-26 , Fig.24 An axonometric view of the housing 11 provided for some other embodiments of the present application; Fig.25 for Fig.24 The structural schematic diagram of the housing 11 is shown; Fig.26 for Fig.24 The schematic diagram of the structure of the housing 11 after unfolding is shown. The housing 11 is formed by bending a plate, and the first and second ends of the plate are connected to each other along the circumference of the opening.

[0250] Taking the shell 11 including the first wall portion 111, the third wall portion 113, the second wall portion 112, and the fourth wall portion 114 connected end to end as an example, the first wall portion 111, the third wall portion 113, the second wall portion 112 and the fourth wall portion 114 are arranged in sequence along the circumference of the opening.

[0251] Along the circumference of the opening, the first and second ends of the plate are respectively a first end 1121 and a second end 1122. Fig.26 As shown, before the shell 11 is formed, the plate has two opposite end surfaces, which are a first end surface 11211 and a second end surface 11221. The plate is offset from the first end surface 11211 in a direction close to the second end surface 11221 by a first preset distance L. 3The portion in the area is the first end portion 1121 of the plate, and the length of the first end portion 1121 is equal to the first preset distance L 3 The plate is offset from the second end surface 11221 in a direction close to the first end surface 11211 by a second preset distance L 4 The portion in the area is the second end portion 1122 of the plate, and the length of the second end portion 1122 is equal to the second preset distance L 4 Among them, the first preset distance L 3 and the second preset distance L 4 They can be equal or unequal.

[0252] The two ends of the plate (the first end 1121 and the second end 1122) can be connected in a variety of ways, such as welding, bonding, hot-melt connection, etc. The connection position 1123 of the two ends can be located on any wall portion of the shell 11, for example, the connection position 1123 of the two ends is located on the first wall portion 111, the second wall portion 112, the third wall portion 113 or the fourth wall portion 114; the connection position 1123 of the two ends can also be located at the intersection of two adjacent walls of the shell 11, and the intersection is the corner area of ​​the shell 11.

[0253] When forming the shell 11 , it is only necessary to bend the plate and connect the two ends of the plate to each other. The forming method of the shell 11 is simple and can effectively reduce the difficulty of forming the shell 11 .

[0254] In some embodiments, along the circumference of the opening, the connection positions 1123 of the two ends are staggered with the first wall portion 111 .

[0255] It is understandable that the connection position 1123 is not located on the first wall portion 111. The connection position 1123 may be located on other walls of the housing 11 except the first wall portion 111, for example, the connection position 1123 is located on the second wall portion 112, the third wall portion 113 or the fourth wall portion 114.

[0256] In this embodiment, the connection position 1123 is not located on the first wall portion 111 , which reduces the influence of the connection position 1123 on the pressure relief mechanism 3 and improves the reliability of the pressure relief mechanism 3 .

[0257] In some embodiments, please refer to Figure 24-26 The shell 11 includes a second wall portion 112 . Along the second direction Y, the first wall portion 111 and the second wall portion 112 are arranged opposite to each other, and the connection position 1123 of the two ends is located on the second wall portion 112 .

[0258] As an example, the first and second ends of the plate together form the second wall portion 112, that is, a portion of the second wall portion 112 is the first end portion 1121, and the other portion of the second wall portion 112 is the second end portion 1122. The end surfaces of the two ends are connected to each other, and the connection between the end surfaces of the two ends forms a connection position 1123. That is, the first end surface 11211 of the first end portion 1121 is connected to the second end surface 11221 of the second end portion 1122.

[0259] As an example, the two ends are connected by welding. When welding, the welding can be performed along the weld formed between the first end surface 11211 and the second end surface 11221.

[0260] In this embodiment, the pressure relief mechanism 3 and the connection position 1123 are respectively located on the opposite first wall portion 111 and the second wall portion 112. The pressure relief mechanism 3 and the connection position 1123 are further apart in the circumferential direction of the opening, further reducing the influence of the connection position 1123 on the pressure relief mechanism 3. 2 <L 1 In the embodiment, when the electrode assembly 2 expands, the first wall portion 111 and the second wall portion 112 are affected by the electrode assembly 2 less than the third wall portion 113 and the fourth wall portion 114, and the deformation of the first wall portion 111 and the second wall portion 112 is less than the deformation of the third wall portion 113 and the fourth wall portion 114. Since the connection position 1123 is located in the second wall portion 112, the influence of the expansion of the electrode assembly 2 on the connection position 1123 can be reduced, and the probability of the shell 11 being damaged from the connection position 1123 due to the expansion of the electrode assembly 2 is reduced.

[0261] In some embodiments, the housing 11 is a rectangular parallelepiped housing, and an opening is formed at at least one end of the housing 11 in the length direction thereof.

[0262] As an example, the housing 11 has openings at both ends in the third direction Z, and the third direction Z is the length direction of the housing 11. The housing 11 includes a first wall portion 111, a third wall portion 113, a second wall portion 112, and a fourth wall portion 114 connected end to end in sequence, the first wall portion 111 and the second wall portion 112 are arranged opposite to each other along the second direction Y, the third wall portion 113 and the fourth wall portion 114 are arranged opposite to each other along the first direction X, the first direction X is the width direction of the housing 11, and the second direction Y is the height direction of the housing 11.

[0263] In this embodiment, the shell 11 is a rectangular shell with a simple structure and is easy to form. Since the shell 11 is a rectangular shell, for the traditional wound electrode assembly 2, the winding center line of the wound electrode assembly 2 extends along the length direction of the shell 11, and the discharge medium generated inside the electrode assembly 2 needs to be discharged from both ends of the electrode assembly 2 along the direction of the winding center line, and then reach the pressure relief mechanism 3 from the gap between the electrode assembly 2 and the wall of the shell 11. The path for the discharge medium to flow to the pressure relief mechanism 3 is very long, and the use of the laminated electrode assembly 2 can effectively shorten the path for the discharge medium to reach the pressure relief mechanism 3, thereby improving the timeliness of the pressure relief of the battery cell 10.

[0264] In some embodiments, please refer to Fig. 22 and Fig.24 , the length of the shell 11 is a, the width of the shell 11 is b, the height of the shell 11 is c, and b≤c≤a / 1.5.

[0265] It can be understood that a / c≥1.5, and a / c can be any point value among 1.5, 2, 3, 4, 5, etc., or a range value between any two. It can be b<c or b=c. Fig. 22 and Fig.24 In the illustrated embodiment, b<c.

[0266] In this embodiment, a / c≥1.5, and the shell 11 is in the shape of a long strip, which can meet the large capacity requirements of the battery cell 10. In the embodiment where the shell 11 is formed by bending a plate, since the shell 11 is in the shape of a long strip, the shell 11 formed by bending a plate is easier to form than the traditional stamping or drawing forming shell 11, and the forming efficiency and the finished product quality rate are higher, especially for thin-walled shells with a wall thickness of no more than 0.6 mm.

[0267] In some embodiments, please refer to Fig. 27 , Fig. 27 The schematic diagram of the structure of the electrode assembly 2 provided in some embodiments of the present application. The electrode assembly 2 includes a plurality of first pole pieces 22 and a plurality of second pole pieces 23. The first pole pieces 22 and the second pole pieces 23 are arranged alternately along the first direction X. Along the second direction Y, the first wall portion 111 ( Fig. 27 The device (not shown) is arranged facing the edge of the first pole piece 22 and the edge of the second pole piece 23.

[0268] The number of the first pole piece 22 and the second pole piece 23 may be equal; the number of the first pole piece 22 and the second pole piece 23 may also be different, for example, one of the first pole piece 22 and the second pole piece 23 has one more than the other. Fig. 27 In the embodiment, the first pole piece 22 is a positive pole piece, the second pole piece 23 is a negative pole piece, there is one more second pole piece 23 than the first pole piece 22 , and one first pole piece 22 is arranged between the two second pole pieces 23 .

[0269] The electrode assembly 2 may further include a separator 24, which is configured to insulate and isolate the first electrode sheet 22 and the second electrode sheet 23. As an example, the separator 24 is a folded structure, and the separator 24 includes a plurality of separators arranged at intervals along the first direction X, and a separator is provided between adjacent first electrode sheets 22 and second electrode sheets 23.

[0270] exist Fig. 27 In the embodiment, along the second direction Y, the edge of the first pole piece 22 facing the first wall portion 111 is the first edge 221 , and the edge of the second pole piece 23 facing the first wall portion 111 is the second edge 231 .

[0271] In this embodiment, the first pole piece 22 and the second pole piece 23 are not folded structures. The emissions generated by the first pole piece 22 and the second pole piece 23 when the battery cell 10 thermally runs away can quickly reach the pressure relief mechanism 3, shortening the time for the emission medium to reach the pressure relief mechanism 3 and improving the timeliness of the pressure relief of the battery cell 10.

[0272] In some embodiments, please refer to Fig.28 and Fig.29 , Fig.28 A schematic diagram of the structure of an electrode assembly 2 provided in some other embodiments of the present application; Fig.29 for Fig.28 The electrode assembly 2 is a partial enlarged view at K. The electrode assembly 2 includes a plurality of first pole pieces 22, and the second pole piece 23 includes a bent portion 232 and a plurality of straight portions 233. Two adjacent straight portions 233 are connected to a bent portion 232. Along the first direction X, the straight portions 233 and the first pole pieces 22 are alternately arranged. Along the second direction Y, the first wall portion 111 ( Fig.28 and Fig.29 The edge of the first pole piece 22 and the bent portion 232 of the second pole piece 23 (not shown) are arranged facing each other.

[0273] The second pole piece 23 is a folded structure. The straight portion 233 is the portion where the second pole piece 23 and the first pole piece 22 are stacked along the first direction X. The bent portion 232 is the portion where the second pole piece 23 is bent. One bent portion 232 connects two straight portions 233. The bent portion 232 may be in an arc shape. The number of straight portions 233 in the second pole piece 23 may be equal to or different from the number of the first pole piece 22. As an example, Fig.28 and Fig.29 In the embodiment, the first pole piece 22 is a positive pole piece, the second pole piece 23 is a negative pole piece, the second pole piece 23 has one more straight portion 233 than the first pole piece 22 , and a first pole piece 22 is arranged between the two straight portions 233 .

[0274] The electrode assembly 2 may further include a separator 24, which is configured to insulate and isolate the first pole piece 22 and the second pole piece 23. As an example, the separator 24 is a folded structure that is stacked and folded together with the second pole piece 23. Two separators 24 are provided in the electrode assembly 2, and the two separators 24 are respectively provided on both sides of the second pole piece 23 and folded together with the second pole piece 23.

[0275] exist Fig.29 In the second direction Y, the edge of the first pole piece 22 facing the first wall portion 111 is the first edge 221. The first wall portion 111 is arranged facing the first edge 221 and facing the bending portion 232 located at one end of the straight portion 233 close to the first wall portion 111.

[0276] During molding, multiple first pole pieces 22 can be arranged on both sides of the second pole piece 23, and then the second pole piece 23 can be folded back and forth so that the second pole piece 23 forms a straight portion 233 and a bent portion 232, thereby achieving alternating arrangement of the straight portion 233 and the first pole piece 22. The molding method of the electrode assembly 2 is simple and the molding efficiency is high.

[0277] In some embodiments, the first wall portion 111 is configured to support the electrode assembly 2 .

[0278] Along the second direction Y, the first wall portion 111 is located at the bottom of the electrode assembly 2. The first wall portion 111 can directly support the electrode assembly 2, so that the electrode assembly 2 is directly in contact with the first wall portion 111; the first wall portion 111 can also support the electrode assembly 2 through an intermediate member, for example, the first wall portion 111 supports the electrode assembly 2 through the first insulating member 5; for another example, the first wall portion 111 supports the electrode assembly 2 through the first insulating member 5 and the support member 7.

[0279] In this embodiment, the pressure relief mechanism 3 on the first wall portion 111 is located at the bottom of the electrode assembly 2, which is conducive to the rapid discharge of the discharge medium inside the battery cell 10 through the pressure relief mechanism 3 by its own gravity. When the battery cell 10 is in thermal runaway, the battery cell 10 can discharge the discharge medium toward the bottom of the battery cell 10 through the pressure relief mechanism 3, reducing the probability of the discharge medium causing damage to the electrical components located at the top of the battery cell 10.

[0280] In some embodiments, the first direction X is perpendicular to the second direction Y.

[0281] An embodiment of the present application provides a battery 100, comprising a battery cell 10 provided in any one of the above embodiments.

[0282] An embodiment of the present application provides an electrical device, including a battery cell 10 provided by any one of the above embodiments, and the battery cell 10 is used to provide electrical energy to the electrical device.

[0283] Please refer to Figure 4-Figure 10 The embodiment of the present application also provides a battery cell 10, which includes a housing 1, an electrode assembly 2, a pressure relief mechanism 3, an electrode terminal 4 and a first insulating member 5. The electrode assembly 2 is accommodated in the housing 1, and the electrode assembly 2 is a laminated electrode assembly 2, which includes a separator 24 and a first pole piece 22 and a second pole piece 23 with opposite polarities, and the separator 24 is arranged between the first pole piece 22 and the second pole piece 23, and a plurality of first pole pieces 22 and a plurality of second pole pieces 23 are stacked along a first direction X. The housing 1 includes a shell 11 and an end cover 12, and the shell 11 includes a first wall portion 111, a third wall portion 113, a second wall portion 112 and a fourth wall portion 114 connected in sequence from end to end, and the first wall portion 111 and the second wall portion 112 are arranged opposite to each other along the second direction Y, and the third wall portion 113 and the fourth wall portion 114 are arranged opposite to each other along the first direction X. Along the third direction Z, the two opposite ends of the housing 11 form openings, and the end caps 12 correspond to the housing 11 one by one, and the end caps 12 close the openings of the housing 11. The end caps 12 are provided with electrode terminals 4, and the electrode terminals 4 are electrically connected to the pole ears 21 of the electrode assembly 2. Along the second direction Y, the first wall portion 111 is provided facing the edge of the first pole piece 22 and the edge of the second pole piece 23, and the pressure relief mechanism 3 is provided on the first wall portion 111. Among them, the first direction X, the second direction Y, and the third direction Z are perpendicular to each other.

[0284] Along the first direction X, the width of the pressure relief region 31 of the pressure relief mechanism 3 is D, and the thickness of the first pole piece 22 is T. 1 , the thickness of the second pole piece 23 is T 2 , the thickness of the spacer 24 is T 3 , the first electrode sheet 22 is a positive electrode sheet, the number of layers of the first electrode sheet 22 in the electrode assembly 2 is N, and satisfies: 4 / 3·N·(T 1 +T 2 +2·T 3 )≥D≥1 / 3·N·(T 1 +T 2 +2·T 3 ), 75μm≤T 1 ≤220μm; 80μm≤T 2 ≤250μm; 5μm≤T 3 ≤20μm.

[0285] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0286] The above embodiments are only used to illustrate the technical solution of the present application and are not used to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, characterized in that: include: The housing comprises a shell and an end cover, wherein the shell has an opening and the end cover closes the opening, and the shell comprises a first wall portion, wherein the first wall portion is disposed adjacent to the end cover; An electrode assembly, contained in the housing, comprising a first pole piece and a second pole piece with opposite polarities, wherein the first pole piece and the second pole piece are stacked along a first direction; Wherein, along the second direction, the first wall portion is arranged facing the edge of the first pole piece and / or the edge of the second pole piece, the second direction intersects with the first direction, and the first wall portion is provided with a pressure relief mechanism.

2. The battery cell according to claim 1, characterized in that: Along the first direction, the thickness of the electrode assembly is T, and the width of the pressure relief area of ​​the pressure relief mechanism is D, satisfying: D≥1 / 3·T.

3. The battery cell according to claim 2, characterized in that: D≥1 / 2·T.

4. The battery cell according to claim 2, characterized in that: The housing has two first outer surfaces, the two first outer surfaces are arranged opposite to each other along the first direction, the first wall portion has a second outer surface, and the two first outer surfaces are connected to the second outer surface through a rounded surface; Along the first direction, the distance between the two first outer surfaces is W, and the radius of the rounded surface is R, satisfying: D≤W-2·R.

5. The battery cell according to claim 1, characterized in that: The electrode assembly further includes a separator, which is disposed between the first pole piece and the second pole piece, and is configured to insulate and isolate the first pole piece from the second pole piece; Along the first direction, the width of the pressure relief area of ​​the pressure relief mechanism is D, the thickness of the first pole sheet is T1, the thickness of the second pole sheet is T2, the thickness of the isolation member is T3, the first pole sheet is a positive pole sheet, and the number of layers of the first pole sheets in the electrode assembly is N, satisfying: D≥1 / 3·N·(T1+T2+2·T3).

6. The battery cell according to claim 5, characterized in that: D≤4 / 3·N·(T1+T2+2·T3).

7. The battery cell according to claim 5, characterized in that: N·(T1+T2+2·T3)≥D≥1 / 2·N·(T1+T2+2·T3).

8. The battery cell according to claim 5, characterized in that: 75μm≤T1≤220μm; and / or, 80μm≤T2≤250μm; and / or, 5μm≤T3≤20μm.

9. The battery cell according to claim 1, characterized in that: Along the second direction, the projection of the electrode assembly completely covers the pressure relief area of ​​the pressure relief mechanism.

10. The battery cell according to claim 1, characterized in that: The battery cell further includes a first insulating member, and along the second direction, the first insulating member is at least partially disposed between the electrode assembly and the first wall portion.

11. The battery cell according to claim 10, characterized in that: The first insulating member is provided with a first drain area configured to allow the drain medium inside the battery cell to move from a side of the first insulating member facing away from the pressure relief mechanism to a side of the first insulating member facing the pressure relief mechanism.

12. The battery cell according to claim 11, characterized in that: The first discharge area includes a first through hole disposed on the first insulating member.

13. The battery cell according to claim 10, characterized in that: The battery cell further includes a support member, which is at least partially disposed between the first insulating member and the first wall portion along the second direction, and is configured to support the first insulating member and the electrode assembly.

14. The battery cell according to claim 13, characterized in that: The support member is provided with a second discharge area configured to allow the discharge medium inside the battery cell to move from a side of the support member facing away from the pressure relief mechanism to a side of the support member facing the pressure relief mechanism.

15. The battery cell according to claim 14, characterized in that: The second discharge area includes a second through hole disposed on the support member.

16. The battery cell according to claim 10, characterized in that: The first insulating member is wrapped around the electrode assembly.

17. The battery cell according to claim 1, characterized in that: The pressure relief mechanism is integrally formed with the first wall portion.

18. The battery cell according to claim 17, characterized in that: The inner surface and / or the outer surface of the first wall portion is provided with a groove, and the bottom wall of the groove forms the pressure relief mechanism.

19. The battery cell according to claim 1, characterized in that: The pressure relief mechanism is separately provided from the first wall portion, and the pressure relief mechanism is installed on the first wall portion.

20. The battery cell according to any one of claims 1 to 19, characterized in that: The pressure relief mechanism is provided with a notched groove, the notched groove defines a pressure relief area, and the pressure relief area is configured to open when the battery cell is depressurized.

21. The battery cell according to claim 20, characterized in that The notched groove is a groove extending along a closed track.

22. The battery cell according to any one of claims 1 to 19, characterized in that: The shell includes the first wall portion, the second wall portion, the third wall portion and the fourth wall portion, the first wall portion, the third wall portion, the second wall portion and the fourth wall portion are connected end to end in sequence, the first wall portion and the second wall portion are arranged opposite to each other along the second direction, and the third wall portion and the fourth wall portion are arranged opposite to each other along the first direction.

23. The battery cell according to claim 22, characterized in that: Along the second direction, the distance between the first wall portion and the second wall portion is L1; along the first direction, the distance between the third wall portion and the fourth wall portion is L2, satisfying: L2<L1.

24. The battery cell according to claim 1, characterized in that: The shell is formed by bending a plate, and along the circumference of the opening, the first and second ends of the plate are connected to each other.

25. The battery cell according to claim 24, characterized in that Along the circumference of the opening, connection positions of the two end portions are offset from the first wall portion.

26. The battery cell according to claim 24 or 25, characterized in that: The shell includes a second wall portion. Along the second direction, the first wall portion and the second wall portion are arranged opposite to each other, and the connection position of the two end portions is located on the second wall portion.

27. The battery cell according to any one of claims 1 to 19, characterized in that: The shell is a rectangular parallelepiped shell, and the opening is formed at at least one end of the shell in the length direction.

28. The battery cell according to claim 27, characterized in that: The length of the shell is a, the width of the shell is b, the height of the shell is c, and b≤c≤a / 1.

5.

29. The battery cell according to any one of claims 1 to 19, characterized in that: The electrode assembly includes a plurality of the first pole pieces and a plurality of the second pole pieces, and along the first direction, the first pole pieces and the second pole pieces are alternately arranged; Along the second direction, the first wall portion is arranged facing an edge of the first pole piece and an edge of the second pole piece.

30. The battery cell according to any one of claims 1 to 19, characterized in that: The electrode assembly includes a plurality of first pole pieces, the second pole piece includes a bent portion and a plurality of straight portions, two adjacent straight portions are connected to one bent portion, and along the first direction, the straight portions and the first pole pieces are alternately arranged; Along the second direction, the first wall portion is arranged facing the edge of the first pole piece and the bent portion of the second pole piece.

31. The battery cell according to any one of claims 1 to 19, characterized in that: The first wall portion is configured to support the electrode assembly along a gravity direction.

32. The battery cell according to any one of claims 1 to 19, characterized in that: The first direction is perpendicular to the second direction.

33. A battery comprising the battery cell according to any one of claims 1 to 32.

34. An electrical device, comprising a battery cell as claimed in any one of claims 1 to 32, wherein the battery cell is used to provide electrical energy to the electrical device.

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