Battery cell, battery, and electrical device

Abstract

Provided in the embodiments of the present application are a battery cell, a battery, and an electrical device. The battery comprises a housing and an electrode assembly, the electrode assembly being flat, and the housing accommodating the electrode assembly. The housing comprises a first wall portion and a second wall portion which are adjacent and connected to one another, the first wall portion being provided with a pressure relief mechanism, and the second wall portion being disposed opposite to the electrode assembly along the thickness direction of the electrode assembly. The second wall portion is provided with a protruding portion, the protruding portion being used to reinforce the second wall portion. The protruding portion can reinforce the second wall portion so as to improve the deformation resistance of the second wall portion. When the electrode assembly expands along the thickness direction thereof, the presence of the protruding portion can reduce the deformation amount of the second wall portion, thus reducing the impact of the second wall portion on the first wall portion, reducing the deformation amount of the first wall portion, improving the anti-fatigue strength of the pressure relief mechanism on the first wall portion, and prolonging the service life of the battery cell.

Description

Battery cells, batteries and electrical equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application (202311461809.X) entitled “Battery Cell, Battery and Electrical Equipment” filed on November 3, 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] With the development of new energy technology, batteries are used more and more widely, for example, in mobile phones, laptops, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and power tools.

[0005] Typical battery cells are equipped with a pressure relief mechanism. In the event of thermal runaway, this mechanism releases internal pressure to improve reliability. In addition to improving battery reliability, the lifespan of battery cells is also a consideration. Therefore, increasing the lifespan of battery cells is a pressing issue in battery technology.

[0006] Summary of the Invention

[0007] The embodiments of the present application provide a battery cell, a battery, and an electrical device, which can effectively improve the service life of the battery cell.

[0008] In a first aspect, an embodiment of the present application provides a battery cell comprising a shell and an electrode assembly; the electrode assembly is flat; the shell accommodates the electrode assembly, and the shell comprises a first wall portion and a second wall portion that are adjacent and connected, the first wall portion being provided with a pressure relief mechanism, and the second wall portion being arranged opposite to the electrode assembly along the thickness direction of the electrode assembly; wherein the second wall portion is provided with a protrusion, and the protrusion is used to strengthen the second wall portion.

[0009] In the above technical solution, the second wall is provided with a protrusion, which strengthens the second wall and improves its deformation resistance. When the electrode assembly expands along its thickness, the protrusion can reduce the deformation of the second wall, thereby reducing the impact of the second wall on the first wall. This reduces the deformation of the first wall, improves the fatigue resistance of the pressure relief mechanism on the first wall, and thus increases the service life of the battery cells.

[0010] In some embodiments, the first wall portion and the second wall portion are connected by a first corner portion; along a first direction, the second wall portion has a first end and a second end opposite each other, the first corner portion is connected to the first end, and the protrusion extends from the first corner portion toward the second end, with the first direction intersecting the thickness direction of the electrode assembly. In this way, the protrusion effectively strengthens at least the region of the second wall portion proximate to the first wall portion along the first direction, reducing the deformation resistance of this region, thereby further strengthening the first wall portion, further reducing the deformation of the first wall portion during expansion of the electrode assembly, and further improving the fatigue strength of the pressure relief mechanism.

[0011] In some embodiments, the protrusion is spaced apart from the second end along the first direction. In this way, the protrusion does not extend to the second end of the second wall portion, so that the dimension of the protrusion along the first direction is not too long, thereby reducing the difficulty of forming the protrusion.

[0012] In some embodiments, along the first direction, the maximum dimension of the second wall is H, and the maximum dimension of the portion of the protrusion located on the second wall is H1, satisfying the following: H1 / H ≤ 0.5. This ensures that the protrusion's dimension along the first direction on the second wall does not exceed an excessively large portion, reduces the difficulty of molding the protrusion, and improves cost-effectiveness.

[0013] In some embodiments, 0.1 mm ≤ H1 ≤ 50 mm. When H1 ≥ 0.1 mm, the protrusion effectively reinforces the first wall, reducing deformation of the first wall during expansion of the electrode assembly. When H1 ≤ 50 mm, the protrusion's dimension along the first direction is not excessive, reducing the difficulty of forming the protrusion. This achieves both the reinforcement effect of the protrusion and cost-effectiveness.

[0014] In some embodiments, 1 mm ≤ H1 ≤ 20 mm, so that the protrusion can better reinforce the first wall portion and further reduce the difficulty of forming the protrusion.

[0015] In some embodiments, the portion of the protrusion located on the second wall gradually decreases in the thickness direction of the electrode assembly from the first end to the second end. This increases the thickness of the protrusion near the first wall, thereby strengthening the first wall and improving its deformation resistance, thereby reducing deformation of the first wall during expansion of the electrode assembly.

[0016] In some embodiments, along the thickness direction of the electrode assembly, the protrusion is provided on the outer surface of the second wall portion, the maximum dimension of the protrusion protruding from the outer surface of the second wall portion is W1, and the minimum distance between the pressure relief mechanism and the outer surface of the second wall portion is W2, which satisfies: 0.3 mm 2 ≤W1×W2≤100mm 2 W1×W2≥0.3mm 2, can improve the fatigue strength of the pressure relief mechanism; W1×W2≤100mm 2 , which can not only reduce material waste, but also improve the pressure relief capacity of battery cells.

[0017] In some embodiments, 1 mm 2 ≤W1×W2≤20mm 2 .

[0018] In some embodiments, the housing further comprises a third wall portion, wherein the first wall portion, the second wall portion, and the third wall portion are adjacent and connected in pairs, the first wall portion is located on one side of the second wall portion along the first direction, and the third wall portion is located on one side of the second wall portion along the second direction, and the first direction, the second direction, and the thickness direction of the electrode assembly intersect in pairs; wherein, along the second direction, the protrusion has opposing third and fourth ends, and the pressure relief mechanism is located between the third and fourth ends. In this way, the pressure relief mechanism is located within the effective reinforcement range of the protrusion in the second direction, so that the protrusion can better reinforce the entire area of ​​the first wall portion where the pressure relief mechanism is provided, further improving the fatigue resistance of the pressure relief mechanism.

[0019] In some embodiments, along the second direction, a third wall portion is provided on both sides of the second wall portion. The minimum distance between the third end and the outer surface of one third wall portion is A1, the minimum distance between the fourth end and the outer surface of the other third wall portion is A2, and the minimum distance between the outer surfaces of the two third wall portions is A, satisfying the following relationship: |(A1-A2) / A|≤0.2. Along the second direction, the middle region of the first wall portion is most susceptible to deformation. However, |(A1-A2) / A|≤0.2, allowing the protrusion to better reinforce the middle region of the first wall portion, thereby improving the deformation resistance of the middle region of the first wall portion and further enhancing the fatigue resistance of the pressure relief mechanism.

[0020] In some embodiments, |(A1-A2) / A|≤0.05. Further reducing the distance between the midpoint of the protrusion in the second direction and the midpoint of the second wall in the second direction allows the protrusion to effectively reinforce the middle region of the second wall, further enhancing the reinforcing effect of the protrusion on the middle region of the first wall.

[0021] In some embodiments, along the thickness direction of the electrode assembly, the second wall portion includes an overlapping region that overlaps with the protrusion and a non-overlapping region that does not overlap with the protrusion. The overlapping region and the protrusion together form a thickened region, and the maximum thickness of the thickened region is greater than the maximum thickness of the non-overlapping region. In this way, the protrusion can be formed by thickening a local area of ​​the second wall portion, which reduces the difficulty of forming the protrusion.

[0022] In some embodiments, the protrusion is disposed on the outer surface of the second wall portion. The protrusion does not occupy the space inside the housing, thereby freeing up more space for the electrode assembly.

[0023] In some embodiments, the housing has an opening disposed opposite the first wall. A pressure relief mechanism is disposed on the first wall of the housing opposite the opening to relieve pressure from the bottom of the housing, thereby facilitating the discharge of emissions generated by thermal runaway of the battery cells from within the housing.

[0024] In some embodiments, a second wall portion is provided on both sides of the first wall portion along the thickness direction of the electrode assembly. The protrusions on the second wall portions on both sides of the first wall portion can reinforce the first wall portion, further reducing the deformation of the first wall portion during expansion of the electrode assembly and further improving the fatigue strength of the pressure relief mechanism.

[0025] In some embodiments, the first wall portion is provided with a first groove to form a corresponding pressure relief mechanism. The first wall portion is configured to rupture along the first groove to release pressure within the battery cell. Providing the first groove on the first wall portion to form a corresponding pressure relief mechanism simplifies the molding process and facilitates control of the pressure relief mechanism's burst pressure. This integral molding of the pressure relief mechanism and the first wall portion provides enhanced structural stability.

[0026] In some embodiments, the first slot includes a first slot section, a second slot section, and a third slot section, with the first slot section and the third slot section being disposed opposite each other, and the second slot section connecting the first and third slot sections. In the event of thermal runaway of the battery cell, the first wall portion can rupture along the first, second, and third slot sections, allowing the area defined by the first, second, and third slot sections to open outward to release pressure, thereby providing the pressure relief mechanism with a larger pressure relief area.

[0027] In some embodiments, the residual thickness of the first and third slot sections is smaller than the residual thickness of the second slot section. This increases the residual thickness of the second slot section, improves the fatigue strength of the first wall in the area where the second slot section is located, reduces the risk of the first wall cracking at the location of the second slot section during normal use of the battery cell, improves the long-term reliability of the pressure relief mechanism, and increases the service life of the battery cell.

[0028] In some embodiments, the residual thickness of the first groove segment is D1, and the residual thickness of the second groove segment is D2, satisfying the following: 0.15 ≤ D1 / D2 ≤ 0.95. D1 / D2 ≥ 0.15 ensures that after the first wall portion cracks along the first groove segment, it can quickly crack along the second groove segment, thereby improving the timely pressure relief of the pressure relief mechanism. D1 / D2 ≤ 0.95 reduces the risk of the first wall portion cracking along the second groove segment during normal use of the battery cell, thereby improving the reliability of the pressure relief mechanism. This balances the timely pressure relief and reliability of the pressure relief mechanism.

[0029] In some embodiments, 0.5≤D1 / D2≤0.85. This further improves the overall performance of the battery cell, by keeping the probability of the first wall portion cracking along the second groove segment during normal use of the battery cell low, and by keeping the probability of the battery cell exploding during thermal runaway low.

[0030] In some embodiments, the residual thickness of the third groove segment is D3, satisfying the following: 0.15 ≤ D3 / D2 ≤ 0.95. D3 / D2 ≥ 0.15 ensures that after the first wall portion ruptures along the third groove segment, it can quickly rupture along the second groove segment, thereby improving the timely pressure relief of the pressure relief mechanism. D3 / D2 ≤ 0.95 reduces the risk of the first wall portion rupturing along the second groove segment during normal use of the battery cell, thereby improving the reliability of the pressure relief mechanism. This balances both the timely pressure relief and the reliability of the pressure relief mechanism.

[0031] In some embodiments, 0.5≤D3 / D2≤0.85. This further improves the overall performance of the battery cell, by keeping the probability of the first wall portion cracking along the second groove segment during normal use of the battery cell low, and by keeping the probability of the battery cell exploding during thermal runaway low.

[0032] In some embodiments, the first slot further includes at least one fourth slot segment, located between the first and third slot segments and connected to the second slot segment. The residual thickness of the first and third slot segments are both smaller than the residual thickness of the fourth slot segment. Because the residual thickness of the second slot segment is smaller than the residual thickness of the first and third slot segments, the second slot segment is more difficult to crack than the first and third slot segments. The provision of the fourth slot segment results in more concentrated stress at the junction of the second and fourth slot segments, forming a stress concentration point, weakening the strength of the second slot segment at that location and making it more susceptible to damage, thereby reducing the difficulty of cracking the first wall along the second slot segment. Because the residual thickness of the first and third slot segments are both smaller than the residual thickness of the fourth slot segment, the junction of the fourth slot segment and the second slot segment is more difficult to crack than the junction of the first and second slot segments and the junction of the third and second slot segments. This reduces the possibility of the first wall being deformed by external forces during normal use of the battery cell, resulting in cracking of the first wall at the junction of the fourth and second slot segments, thereby increasing the service life of the battery cell.

[0033] In some embodiments, along the extension direction of the second slot segment, both ends of the second slot segment are connected to the first slot segment and the third slot segment, respectively. Thus, both ends of the second slot segment do not extend beyond the first slot segment and the third slot segment, respectively. During pressure relief, pressure can be accurately relieved through the areas defined by the first, second, and third slot segments, making it less likely to cause cracks in other areas of the first wall during pressure relief, and making it easier to achieve directional pressure relief.

[0034] In some embodiments, the first slot segment, the second slot segment, and the third slot segment are all slots extending along a straight line. The first slot segment, the second slot segment, and the third slot segment are all straight slots, which can reduce the difficulty of forming the first slot segment, the second slot segment, and the third slot segment.

[0035] In some embodiments, the first wall portion is a rectangular wall portion, the second slot segment extends along the length of the first wall portion, and both the first slot segment and the third slot segment extend along the width of the first wall portion. In this way, the first wall portion can provide more space for the second slot segment, allowing the second slot segment to be made longer, thereby increasing the pressure relief area of ​​the pressure relief mechanism.

[0036] In some embodiments, the first wall portion is provided with a second groove, the second groove and the first groove are arranged along the thickness direction of the first wall portion, the second groove includes a fifth groove segment, a sixth groove segment, and a seventh groove segment, the fifth groove segment and the seventh groove segment are arranged opposite each other, and the sixth groove segment connects the fifth groove segment and the seventh groove segment; wherein the first groove segment is provided at the groove bottom surface of the fifth groove segment, the second groove segment is provided at the groove bottom surface of the sixth groove segment, and the third groove segment is provided at the groove bottom surface of the seventh groove segment. The first groove segment, the second groove segment, and the third groove segment are provided at the groove bottom surfaces of the fifth groove segment, the sixth groove segment, and the seventh groove segment, respectively, so that each groove segment in the second groove corresponds to each groove segment in the first groove. When the bursting pressure of the pressure relief mechanism is constant, the depth of the first groove segment, the second groove segment, and the third groove segment can be reduced, thereby reducing the risk of damage to the first wall portion during the formation of the first groove.

[0037] In some embodiments, the first wall portion is provided with a third groove, wherein the third groove, the second groove, and the first groove are arranged along the thickness direction of the first wall portion. The third groove includes an eighth groove segment, a ninth groove segment, and a tenth groove segment, wherein the eighth groove segment and the tenth groove segment are arranged opposite each other, and the ninth groove segment connects the eighth groove segment and the tenth groove segment. The fifth groove segment is provided at the groove bottom surface of the eighth groove segment, the sixth groove segment is provided at the groove bottom surface of the ninth groove segment, and the seventh groove segment is provided at the groove bottom surface of the tenth groove segment. The fifth groove segment, the sixth groove segment, and the seventh groove segment are provided at the groove bottom surfaces of the eighth groove segment, the ninth groove segment, and the tenth groove segment, respectively, so that each groove segment in the third groove corresponds to each groove segment in the second groove, thereby reducing the depth of the fifth groove segment, the sixth groove segment, and the seventh groove segment, thereby reducing the risk of damage to the first wall portion during the formation of the second groove.

[0038] In some embodiments, the first slot segment has a first midplane extending along its extension direction, the second slot segment has a second midplane extending along its extension direction, and the third slot segment has a third midplane extending along its extension direction. The minimum distance from the center point of the outer surface of the first wall to the first midplane is M1, the minimum distance from the center point of the outer surface of the first wall to the second midplane is M2, and the minimum distance from the center point of the outer surface of the first wall to the third midplane is M3, satisfying the following conditions: M2 < M1, M2 < M3. When the internal pressure of the battery cell changes, the first wall segment is more likely to deform closer to the center point, and M2 < M1, M2 < M3. This allows the first and third slot segments to be further away from the center point, thereby improving the fatigue strength of the first wall segment in the first and third slot segments.

[0039] In some embodiments, along the thickness direction of the first wall, the projection of the center point of the outer surface of the first wall lies within the second groove segment; and / or |M3 - M1| ≤ 5 mm. If the projection of the center point of the outer surface of the first wall lies within the second groove segment, the second groove segment is closer to the center point of the outer surface of the first wall, allowing the first wall to rupture along the second groove segment more promptly during pressure relief, thereby improving the timeliness of pressure relief of the pressure relief mechanism. If |M3 - M1| ≤ 5 mm, the first and third groove segments are both farther from the center point of the first wall, reducing the impact of deformation of the first wall near the center point on the first and third groove segments.

[0040] In some embodiments, the first wall portion is provided with a second groove, and the first groove is provided on a groove bottom surface of the second groove.

[0041] In some embodiments, the first wall portion is provided with a third groove, and the second groove is provided on the bottom surface of the third groove.

[0042] In some embodiments, the electrode assembly is a laminated structure, and the stacking direction of the electrode sheets in the electrode assembly is parallel to the thickness direction of the electrode assembly.

[0043] In some embodiments, the electrode assembly is a wound structure, the electrode assembly includes a straight area and a bent area, the bent area is connected to the straight area, and the stacking direction of the electrode sheets in the straight area is parallel to the thickness direction of the electrode assembly.

[0044] 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.

[0045] 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

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. 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 relevant drawings can be obtained based on these drawings without creative work.

[0047] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0048] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0049] FIG3 is an exploded view of a battery cell provided in some embodiments of the present application;

[0050] FIG4 is a schematic structural diagram of the battery cell shown in FIG3 ;

[0051] FIG5 is a schematic structural diagram of the housing shown in FIG4 (the opening of the housing faces upward);

[0052] FIG6 is a schematic structural diagram of the housing shown in FIG4 (the opening of the housing faces downward);

[0053] FIG7 is an XY cross-sectional view of the housing shown in FIG5 ;

[0054] FIG8 is a partial enlarged view of point A of the housing shown in FIG7 ;

[0055] FIG9 is a partial view of a housing provided in some other embodiments of the present application;

[0056] FIG10 is a bottom view of a housing provided in some embodiments of the present application;

[0057] FIG11 is a bottom view of a housing provided in some other embodiments of the present application;

[0058] FIG12 is a bottom view of a housing provided in some other embodiments of the present application;

[0059] FIG13 is a YZ cross-sectional view of a housing provided in some embodiments of the present application;

[0060] FIG14 is a schematic diagram of the connection between the protrusion and the second wall portion provided in some embodiments of the present application;

[0061] FIG15 is a partial view of a first wall portion provided in some embodiments of the present application;

[0062] FIG16 is a BB cross-sectional view of the first wall portion shown in FIG15 ;

[0063] FIG17 is a partial enlarged view of a portion C of the first wall portion shown in FIG16 ;

[0064] FIG18 is a partial enlarged view of a portion D of the first wall portion shown in FIG16 ;

[0065] FIG19 is a partial view of a first wall portion provided in some other embodiments of the present application;

[0066] FIG20 is a schematic structural diagram of a battery cell provided in some other embodiments of the present application;

[0067] FIG21 is a partial enlarged view of point D in FIG20;

[0068] FIG22 is a partial view of the first wall portion shown in FIG21;

[0069] FIG23 is a partial view of a battery cell provided in some other embodiments of the present application;

[0070] FIG24 is a partial view of the first wall portion shown in FIG23;

[0071] FIG25 is a partial view of a first wall portion provided in some further embodiments of the present application;

[0072] FIG26 is a cross-sectional view of a first wall portion provided in some embodiments of the present application;

[0073] FIG27 is a cross-sectional view of a first wall portion provided in some other embodiments of the present application;

[0074] FIG28 is a schematic structural diagram of an electrode assembly provided in some embodiments of the present application;

[0075] FIG29 is a schematic structural diagram of an electrode assembly provided in some other embodiments of the present application.

[0076] Icons: 1-housing; 11-shell; 111-first wall; 1111-outer surface of the first wall; 1111a-center point; 112-second wall; 1121-protrusion; 11211-first surface; 11212-third end; 11213-fourth end; 1122-first end; 1123-second end; 1124-outer surface of the second wall; 1125-overlapping area; 1126-non-overlapping area; 1127-thickened area; 113-third wall; 1131-outer surface of the third wall; 114-first corner; 115-second corner; 116-third corner; 12-end cap; 2-electrode assembly; 21-ear; 22-positive electrode sheet; 23-separator; 24-negative electrode sheet; 241-bending section; 242-stacked section; 25-straight area; 26-bending area; 3-electrode terminal; 4-current collecting member; 5-insulating member; 6-pressure relief mechanism; 61-first slot; 611-first slot section; 6111-first midplane; 612-second slot section; 6121-second midplane Surface; 613-third slot segment; 6131-third midplane; 614-first position; 615-second position; 616-fourth slot segment; 62-second slot; 621-fifth slot segment; 622-sixth slot segment; 623-seventh slot segment; 624-first recess; 63-third slot; 631-eighth slot segment; 632-ninth slot segment; 633-tenth slot segment; 634-second recess; 10-battery cell; 20-housing; 201-first part; 202-second part; 100-battery; 200-controller; 300-motor; 1000-vehicle; X-thickness direction of the electrode assembly; Y-first direction; Z-second direction. DETAILED DESCRIPTION

[0077] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0078] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" 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-secondary relationship.

[0079] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0080] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0081] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0082] The term "plurality" used in this application refers to two or more (including two).

[0083] 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.

[0084] Battery cells include but are not limited to lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0085] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process, active ions (such as lithium ions) move back and forth between the positive and negative electrodes. A separator, placed between the positive and negative electrodes, reduces the risk of short circuits while allowing active ions to pass through.

[0086] In some embodiments, the positive electrode may be a positive electrode sheet, which 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.

[0087] 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 provided on either or both of the two facing surfaces of the positive electrode current collector.

[0088] 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 with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer 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.).

[0089] 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 LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), 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 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc.

[0090] In some embodiments, a positive electrode may be a metal foam. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam, among others. When a metal foam is used as the positive electrode, the surface of the metal foam may or may not be provided with a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled and / or deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0091] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0092] As an example, the negative electrode current collector may be a metal foil, a metal foam, or a composite current collector. For example, the metal foil may be silver-surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium. The metal foam may be nickel foam, copper foam, aluminum foam, or alloy foam. The composite current collector may include a polymer base layer and a metal layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (e.g., a substrate made of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0093] 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.

[0094] 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 provided on either or both of the two facing surfaces of the negative electrode current collector.

[0095] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells that is well 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.

[0096] 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.

[0097] In some embodiments, the separator is a separator membrane, which can be any known porous separator membrane with good chemical and mechanical stability.

[0098] As an example, the separator can be made of at least one of fiberglass, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film. In the case of a multi-layer composite film, the materials of each layer can be the same or different. The separator can be a separate component positioned between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0099] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0100] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel, or solid. Liquid electrolytes include an electrolyte salt and a solvent.

[0101] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0102] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl 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 may also be an ether solvent. The ether solvent may 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.

[0103] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0104] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0105] 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, or the like.

[0106] As an example, the inorganic solid electrolyte may include 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.

[0107] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0108] 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.

[0109] In some embodiments, the electrode assembly is a laminate structure.

[0110] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0111] 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 sections, with a positive electrode sheet being sandwiched between adjacent stacked sections.

[0112] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked segments.

[0113] As an example, a plurality of separators may be provided, each of which is disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0114] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0115] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0116] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0117] In some embodiments, a 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 (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0118] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. Prismatic battery cells include square-shell battery cells, blade-shaped battery cells, and polygonal prismatic batteries. Polygonal prismatic batteries are, for example, hexagonal prismatic batteries.

[0119] 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.

[0120] 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.

[0121] 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 housed in the case.

[0122] 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.

[0123] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0124] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, the reliability of battery cells must also be considered.

[0125] In order to improve the reliability of the battery cell, a pressure relief mechanism can be provided in at least one wall portion of the battery cell shell. The pressure relief mechanism and the corresponding wall portion can be provided separately or integrally formed. When the battery cell thermally runs away, the pressure inside the battery cell can be released through the pressure relief mechanism.

[0126] In a battery cell, for a flat electrode assembly, the wall portion of the shell in the thickness direction of the electrode assembly generally needs to overlap with other battery cells. In order to reduce the obstruction of the pressure relief mechanism by other battery cells, the pressure relief mechanism can be arranged on the wall portion of the shell that is adjacent to and connected to the wall portion.

[0127] During the charge and discharge process of the battery cell, the electrode assembly inside the battery cell may expand. For a flat electrode assembly, the expansion of the electrode assembly is greater in the thickness direction of the electrode assembly, which will cause the wall of the shell in the thickness direction of the electrode assembly to deform significantly. The deformation of the wall may cause the wall of the shell where the pressure relief mechanism is provided to deform under stress. With the long-term expansion and recovery of the electrode assembly, the pressure relief mechanism may easily suffer fatigue damage, causing the pressure relief mechanism to fail, thereby affecting the service life of the battery cell.

[0128] In view of this, an embodiment of the present application provides a battery cell, comprising a housing and an electrode assembly, the electrode assembly being flat and the housing housing the electrode assembly. The housing comprises a first wall portion and a second wall portion that are adjacent and connected to each other. The first wall portion is provided with a pressure relief mechanism, and the second wall portion is disposed opposite the electrode assembly along the thickness direction of the electrode assembly. The second wall portion is provided with a protrusion that is used to reinforce the second wall portion.

[0129] In such a battery cell, the second wall is provided with a protrusion, which reinforces the second wall and improves its deformation resistance. When the electrode assembly expands along its thickness, the protrusion reduces deformation of the second wall, thereby reducing the impact of the second wall on the first wall. This reduces deformation of the first wall, improves the fatigue resistance of the pressure relief mechanism on the first wall, and thus increases the service life of the battery cell.

[0130] The battery cells described in the embodiments of the present application are suitable for batteries and electrical equipment using the battery cells.

[0131] Electrical equipment can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and electric tools, etc. Vehicles can be fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. 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, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical equipment.

[0132] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0133] Please refer to Figure 1, which is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of the present application. A battery 100 is disposed within vehicle 1000. Battery 100 can be located at the bottom, front, or rear of vehicle 1000. Battery 100 can be used to power vehicle 1000, for example, as an operating power source for vehicle 1000.

[0134] The vehicle 1000 may further include a controller 200 and a motor 300 . The controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, to meet the power requirements of the vehicle 1000 during startup, navigation, and driving.

[0135] In some embodiments of the present application, the battery 100 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0136] Please refer to Figure 2, which is an exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 may include a battery cell 10 and a housing 20, wherein the battery cell 10 is accommodated in the housing 20.

[0137] The housing 20 is a component that houses the battery cells 10 and provides a storage space for the battery cells 10. The housing 20 can have various structures. In some embodiments, the housing 20 can include a first portion 201 and a second portion 202, which overlap to define a storage space for the battery cells 10. The first portion 201 and the second portion 202 can have various shapes, such as a rectangular parallelepiped or a cylinder. The first portion 201 can be a hollow structure with one side open, and the second portion 202 can also be a hollow structure with one side open. The open side of the second portion 202 overlaps the open side of the first portion 201, forming the housing 20 with a storage space. Alternatively, the first portion 201 can be a hollow structure with one side open, and the second portion 202 can be a plate-like structure. The second portion 202 overlaps the open side of the first portion 201, forming the housing 20 with a storage space. The first portion 201 and the second portion 202 can be sealed by a sealing element, which can be a sealing ring, sealant, etc.

[0138] In the battery 100, there can be one or more battery cells 10. If there are multiple battery cells 10, the multiple battery cells 10 can be connected in series, parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 10. Multiple battery cells 10 can be connected in series, parallel, or in a hybrid connection to form a battery module, which can then be connected in series, parallel, or in a hybrid connection to form a single unit and housed within the housing 20. Alternatively, all battery cells 10 can be directly connected in series, parallel, or in a hybrid connection, and then the entire unit formed by all battery cells 10 can be housed within the housing 20.

[0139] Please refer to Figure 3, which is an exploded view of a battery cell 10 provided in some embodiments of the present application. The battery cell 10 may include a housing 1 and an electrode assembly 2, wherein the electrode assembly 2 is accommodated in the housing 1.

[0140] In some embodiments, the housing 1 may include a shell 11 and an end cover 12 , wherein the shell 11 has an opening and the end cover 12 closes the opening of the shell 11 .

[0141] The housing 11 is a component for accommodating the electrode assembly 2. The housing 11 can be a hollow structure with an opening at one end, or a hollow structure with openings at opposite ends. The housing 11 can have various shapes, such as a cylinder or a rectangular parallelepiped. The housing 11 can be made of various materials, such as copper, iron, aluminum, steel, and aluminum alloys.

[0142] 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, electrolyte and other components. The end cap 12 can be connected to the shell 11 by welding or rolling to close the opening of the shell 11. The shape of the end cap 12 can be adapted to the shape of the shell 11. For example, the shell 11 is a rectangular parallelepiped structure, and the end cap 12 is a rectangular plate structure adapted to the shell 11. 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.

[0143] In an embodiment where the housing 11 is open at one end, one end cap 12 may be provided. In an embodiment where the housing 11 is open at two opposite ends, two end caps 12 may be provided, each of which closes the two openings of the housing 11, and the two end caps 12 and the housing 11 together define a receiving space.

[0144] In some embodiments, the battery cell 10 may further include an electrode terminal 3, which is disposed on the outer casing 1 and is used to electrically connect to the tab 21 of the electrode assembly 2 to output electrical energy from the battery cell 10. The electrode terminal 3 may be disposed on the shell 11 of the outer casing 1 or on the end cap 12 of the outer casing 1. The electrode terminal 3 and the tab 21 may be directly connected, for example, by welding the electrode terminal 3 to the tab 21. The electrode terminal 3 and the tab 21 may also be indirectly connected, for example, by indirectly connecting the electrode terminal 3 and the tab 21 through a current collecting member 4. The current collecting member 4 may be a metal conductor, such as copper, iron, aluminum, steel, or an aluminum alloy.

[0145] As an example, as shown in FIG3 , an opening is formed at one end of the housing 11, and there is only one end cap 12 in the outer shell 1, and each end cap 12 closes the opening of the housing 11. Two electrode terminals 3 are provided on the end cap 12, namely a positive electrode terminal 3 and a negative electrode terminal 3. A positive electrode tab and a negative electrode tab are formed on the end of the electrode assembly 2 facing the end cap 12. The positive electrode terminal 3 is connected to the positive electrode tab via a current collecting member 4, and the negative electrode terminal 3 is connected to the negative electrode tab via another current collecting member 4.

[0146] 3 , the battery cell 10 may further include an insulating member 5 . The insulating member 5 is a component that separates the housing 11 from the electrode assembly 2 , thereby achieving insulation isolation between the housing 11 and the electrode assembly 2 . The insulating member 5 is made of an insulating material, including but not limited to plastic, rubber, and the like.

[0147] As an example, the insulating member 5 is wrapped around the outside of the electrode assembly 2 along the circumference of the opening of the shell 11. The electrode assembly 2 in the shell 1 can be one or more. If there is one electrode assembly 2, the insulating member 5 is wrapped around the electrode assembly 2; if there are multiple electrode assemblies 2, the multiple electrode assemblies 2 can be stacked along the thickness direction X of the electrode assembly. One insulating member 5 can be provided for each electrode assembly 2, and each insulating member 5 is wrapped around one electrode assembly 2. Alternatively, multiple electrode assemblies 2 can be provided as an integral component, and the insulating member 5 is wrapped around the integral component.

[0148] Please refer to Figures 4 to 6. Figure 4 is a schematic structural diagram of the battery cell 10 shown in Figure 3; Figure 5 is a schematic structural diagram of the shell 11 shown in Figure 4 (the opening of the shell 11 faces upward); Figure 6 is a schematic structural diagram of the shell 11 shown in Figure 4 (the opening of the shell 11 faces downward). An embodiment of the present application provides a battery cell 10, comprising a shell 11 and an electrode assembly 2, the electrode assembly 2 being flat, and the shell 11 accommodating the electrode assembly 2. The shell 11 comprises a first wall portion 111 and a second wall portion 112 that are adjacent and connected, the first wall portion 111 being provided with a pressure relief mechanism 6, and the second wall portion 112 being arranged opposite to the electrode assembly 2 along the thickness direction X of the electrode assembly. The second wall portion 112 is provided with a protrusion 1121, and the protrusion 1121 is used to strengthen the second wall portion 112.

[0149] The electrode assembly 2 may be a laminated structure or a wound structure. The electrode assembly 2 is flat, with a thickness less than both its width and height. The electrode assembly 2 may be roughly rectangular, with the tab 21 formed at at least one end of the electrode assembly 2 in the height direction.

[0150] The first wall 111 and the second wall 112 are two adjacent walls of the housing 11. The first wall 111 and the second wall 112 are connected. The first wall 111 and the second wall 112 can be directly connected or indirectly connected. For example, the first wall 111 and the second wall 112 can be connected through a corner. The second wall 112 is the wall of the housing 11 that is opposite the electrode assembly 2 along the thickness direction X of the electrode assembly. The second wall 112 can be the wall with the largest outer surface area in the housing 11. Taking the housing 11 as an example, in which the housing 11 is a rectangular parallelepiped and has a hollow structure with an opening at one end, the second wall 112 can be the wall along the thickness direction of the battery cell 10, and the thickness direction of the battery cell 10 is parallel to the thickness direction X of the electrode assembly. The first wall 111 can be the wall along the width direction of the battery cell 10. The first wall 111 can also be the wall along the height direction of the battery cell 10. The opening of the housing 11 is located at one end of the housing 11 in the height direction of the battery cell 10. Taking the shell 11 as an example, in which the shell 11 is in the shape of a rectangular parallelepiped and is a hollow structure with openings formed at opposite ends, the second wall portion 112 can be a wall portion in the thickness direction of the battery cell 10, and the thickness direction of the battery cell 10 is parallel to the thickness direction X of the electrode assembly. The first wall portion 111 can be a wall portion in the width direction of the battery cell 10, and the two openings of the shell 11 are respectively located at the two ends of the shell 11 in the height direction of the battery cell 10.

[0151] The pressure relief mechanism 6 is a component within the battery cell 10 used to release internal pressure within the battery cell 10. At least a portion of the pressure relief mechanism 6 has a strength less than that of the first wall portion 111. The pressure relief mechanism 6 can be activated to release internal pressure in the battery cell 10 when the internal pressure of the battery cell 10 reaches its burst pressure. Actuation can be achieved by at least a portion of the pressure relief mechanism 6 rupturing, detaching, or opening. The pressure relief mechanism 6 and the first wall portion 111 can be integrally formed or separately provided. The first wall portion 111 has a pressure relief hole provided therein, and the pressure relief mechanism 6 is mounted to the first wall portion 111 and covers the hole.

[0152] The protrusion 1121 and the second wall portion 112 can be separately provided and connected. For example, the protrusion 1121 is welded to the second wall portion 112. The protrusion 1121 and the second wall portion 112 can also be integrally formed. The protrusion 1121 can be cylindrical, elongated, curved, etc. The curved protrusion 1121 can be formed by extending along an arc trajectory, a V-shaped trajectory, an S-shaped trajectory, etc. The protrusion 1121 can be provided on the inner surface of the second wall portion 112, or on the outer surface 1124 of the second wall portion (not shown in Figures 4-6), or both the outer surface 1124 and the inner surface of the second wall portion can be provided with the protrusion 1121.

[0153] In this embodiment, the second wall portion 112 is provided with a protrusion 1121. The protrusion 1121 can reinforce the second wall portion 112 to improve the deformation resistance of the second wall portion 112. Since the first wall portion 111 and the second wall portion 112 are adjacent to each other, the protrusion 1121 can indirectly reinforce the first wall portion 111. When the electrode assembly 2 expands along its thickness direction, the provision of the protrusion 1121 can reduce the deformation of the second wall portion 112, thereby reducing the impact of the second wall portion 112 on the first wall portion 111, reducing the deformation of the first wall portion 111, and improving the fatigue resistance of the pressure relief mechanism 6 on the first wall portion 111, thereby increasing the service life of the battery cell 10.

[0154] In some embodiments, please continue to refer to Figures 7 and 8. Figure 7 is an XY cross-sectional view of the housing 11 shown in Figure 5; Figure 8 is a partial enlarged view of the portion A of the housing 11 shown in Figure 7. The first wall portion 111 and the second wall portion 112 are connected via a first corner portion 114. Along a first direction Y, the second wall portion 112 has a first end 1122 and a second end 1123 that are oppositely disposed. The first corner portion 114 is connected to the first end 1122, and the protrusion 1121 extends from the first corner portion 114 toward the second end 1123. The first direction Y intersects with the thickness direction X of the electrode assembly.

[0155] The first corner portion 114 is located at a corner of the housing 11. The cross-section of the first corner portion 114 may be arc-shaped, and both the outer surface and the inner surface of the first corner portion 114 may be arc-shaped. The outer surface 1111 of the first wall portion and the outer surface 1124 of the second wall portion may smoothly transition through the outer surface of the first corner portion 114. The inner surface of the first wall portion 111 and the inner surface of the second wall portion 112 may smoothly transition through the inner surface of the first corner portion 114.

[0156] The first direction Y intersects the thickness direction X of the electrode assembly, and the two can be arranged at an obtuse angle, a right angle, or an acute angle. As an example, in the embodiments shown in Figures 7 and 8, the first direction Y is perpendicular to the thickness direction X of the electrode assembly.

[0157] It can be understood that in an embodiment where the first wall portion 111 is the wall portion of the shell 11 in the width direction of the battery cell 10, the first direction Y can be parallel to the width direction of the battery cell 10; in an embodiment where the first wall portion 111 is the wall portion of the shell 11 in the height direction of the battery cell 10, the first direction Y can be parallel to the height direction of the battery cell 10.

[0158] As an example, in Figures 7 and 8, the first wall portion 111 is the wall portion of the shell 11 in the height direction of the battery cell 10. Along the first direction Y, an opening is formed at one end of the shell 11. The first wall portion 111 is located at the other end of the shell 11. The first end 1122 is the end of the second wall portion 112 connected to the first corner portion 114, and the second end 1123 is the end of the second wall portion 112 located at the opening position of the shell 11.

[0159] The protrusion 1121 extends from the first corner portion 114 toward the second end 1123. It is understood that the protrusion 1121 is directly connected to the first corner portion 114. Along the first direction Y, the protrusion 1121 may start extending from the first corner portion 114, with a portion of the protrusion 1121 located at the first corner portion 114 and another portion of the protrusion 1121 located at the second wall portion 112. Along the first direction Y, the protrusion 1121 may also start extending from the first end 1122 to the second wall portion 112, extending from the first end 1122 toward the second end 1123, with the entire protrusion 1121 located at the second wall portion 112. Along the first direction Y, the protrusion 1121 may end extending from the first end 1122 to the second end 1123, or may end extending from the second end 1123.

[0160] In this embodiment, the protrusion 1121 has a good reinforcing effect on at least the area of ​​the second wall portion 112 close to the first wall portion 111 along the first direction Y, reducing the deformation resistance of the area, and thus having a better reinforcing effect on the first wall portion 111, further reducing the deformation of the first wall portion 111 when the electrode assembly 2 expands, and further improving the fatigue strength of the pressure relief mechanism 6.

[0161] In some embodiments, please continue to refer to FIG. 7 and FIG. 8 , along the first direction Y, the protrusion 1121 and the second end 1123 are spaced apart.

[0162] It can be understood that, along the first direction Y, there is a distance between the end of the protrusion 1121 away from the first corner portion 114 and the second end 1123 , that is, the protrusion 1121 does not extend from the first corner portion 114 to the second end 1123 .

[0163] In this embodiment, the protrusion 1121 does not extend to the second end 1123 of the second wall portion 112 , so that the dimension of the protrusion 1121 along the first direction Y is not too long, thereby reducing the difficulty of forming the protrusion 1121 .

[0164] 7 and 8 , along the first direction Y, the maximum dimension of the second wall portion 112 is H, and the maximum dimension of the portion of the protrusion 1121 located on the second wall portion 112 is H1, satisfying: H1 / H≤0.5.

[0165] As an example, the first direction Y is parallel to the height direction of the battery cell 10. Along the first direction Y, the maximum dimension of the second wall portion 112 is the height of the second wall portion 112, and the maximum dimension of the portion of the protrusion 1121 located on the second wall portion 112 is the height of the portion of the protrusion 1121 located on the second wall portion 112.

[0166] H1 / H can be any one of 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, 0.03, 0.01, etc., or a range of values ​​between any two of them.

[0167] In this embodiment, H1 / H≤0.5, so that the size of the protrusion 1121 on the second wall portion 112 along the first direction Y does not account for too large a proportion, thereby reducing the difficulty of forming the protrusion 1121 and achieving better economy.

[0168] In some embodiments, 0.01≤H1 / H≤0.2.

[0169] In this embodiment, H1 / H can be any point value among 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 2, etc., or a range value between any two of them.

[0170] In this embodiment, H1 / H≤0.2, which further reduces the size ratio of the protrusion 1121 on the second wall portion 112 along the first direction Y, and further reduces the difficulty of forming the protrusion 1121; H1 / H≥0.01, so that the size ratio of the protrusion 1121 on the second wall portion 112 along the first direction Y is not too small, so that the protrusion 1121 can play a good reinforcing role on the first wall portion 111.

[0171] In some embodiments, 0.1 mm ≤ H1 ≤ 50 mm.

[0172] In this embodiment, H1 can be any point value among 0.1mm, 1mm, 3mm, 5mm, 8mm, 10mm, 13mm, 15mm, 18mm, 20mm, 23mm, 25mm, 28mm, 30mm, 33mm, 35mm, 38mm, 40mm, 43mm, 45mm, 48mm, 50mm, etc., or a range value between any two of them.

[0173] In this embodiment, H1 is ≥ 0.1 mm, allowing the protrusion 1121 to effectively reinforce the first wall 111 and reduce the deformation of the first wall 111 when the electrode assembly 2 expands. H1 is ≤ 50 mm, so that the dimension of the protrusion 1121 along the first direction Y is not too large, reducing the difficulty of forming the protrusion 1121. In this way, both the reinforcement effect of the protrusion 1121 and economic efficiency are taken into account.

[0174] In some embodiments, 1 mm ≤ H1 ≤ 20 mm.

[0175] In this embodiment, H1 can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm, 19mm, or 20mm.

[0176] In this embodiment, 1 mm ≤ H1 ≤ 20 mm, so that the protrusion 1121 has a better reinforcement effect on the first wall portion 111 and further reduces the difficulty of forming the protrusion 1121 .

[0177] In some embodiments, referring to FIG. 8 , the size of the portion of the protrusion 1121 located on the second wall portion 112 in the thickness direction X of the electrode assembly gradually decreases from the middle to both ends in the first direction Y.

[0178] In some embodiments, referring to FIG9 , which is a partial view of the housing 11 provided in other embodiments of the present application, the portion of the protrusion 1121 located on the second wall portion 112 gradually decreases in size in the thickness direction X of the electrode assembly, along the direction from the first end 1122 to the second end 1123 .

[0179] As an example, the protrusion 1121 has a first surface 11211, and the distance between the outer surface 1124 of the second wall portion and the first surface 11211 in the thickness direction X of the electrode assembly gradually decreases along the direction from the first end 1122 to the second end 1123, so that the size of the portion of the protrusion 1121 located on the second wall portion 112 in the thickness direction X of the electrode assembly gradually decreases along the direction from the first end 1122 to the second end 1123. The first surface 11211 can be an inclined plane or an arc surface, etc.

[0180] In this embodiment, the protrusion 1121 has a greater thickness in the area close to the first wall portion 111, which better strengthens the first wall portion 111 and improves the deformation resistance of the first wall portion 111, thereby reducing the deformation of the first wall portion 111 when the electrode assembly 2 expands.

[0181] In some embodiments, please refer to Figures 10 to 12. Figure 10 is a bottom view of the shell 11 provided in some embodiments of the present application (observed from the direction from which the first wall portion 111 points to the opening of the shell 11); Figure 11 is a bottom view of the shell 11 provided in some other embodiments of the present application (observed from the direction from which the first wall portion 111 points to the opening of the shell 11); Figure 12 is a bottom view of the shell 11 provided in some other embodiments of the present application (observed from the direction from which the first wall portion 111 points to the opening of the shell 11). Along the thickness direction X of the electrode assembly, the protrusion 1121 is provided on the outer surface of the second wall portion 112 (shown in Figures 8 and 9), and the maximum dimension of the protrusion 1121 protruding from the outer surface 1124 of the second wall portion is W1, and the minimum distance between the pressure relief mechanism 6 and the outer surface 1124 of the second wall portion is W2, satisfying: 0.3 mm 2 ≤W1×W2≤100mm 2 .

[0182] The maximum dimension of the protrusion 1121 protruding from the outer surface 1124 of the second wall is the maximum thickness of the protrusion 1121 along the thickness direction X of the electrode assembly, and is also the dimension of the protrusion 1121 at the thickest position along the thickness direction X of the electrode assembly. The minimum distance between the pressure relief mechanism 6 and the outer surface 1124 of the second wall is the distance between the position of the pressure relief mechanism 6 closest to the outer surface 1124 of the second wall and the outer surface 1124 of the second wall along the thickness direction X of the electrode assembly.

[0183] W1×W2 can be 0.3mm 2 , 1mm 2 , 5mm 2 , 10mm 2 , 20mm 2 , 30mm 2 , 40mm 2 , 50mm 2 , 60mm 2 , 70mm 2 , 80mm 2 , 90mm 2 , 100mm 2 Any point value or any range of values ​​between the two.

[0184] If W1 is too small, the maximum dimension of the protrusion 1121 protruding from the outer surface 1124 of the second wall portion is small, and the reinforcement capability of the protrusion 1121 is poor. If W2 is too small, the dimension of the pressure relief mechanism 6 along the thickness direction X of the electrode assembly is large, which results in relatively poor fatigue strength of the pressure relief mechanism 6. If W1 is too large, the maximum dimension of the protrusion 1121 protruding from the outer surface 1124 of the second wall portion is large. If W2 is too large, the dimension of the pressure relief mechanism 6 along the thickness direction X of the electrode assembly is small. Thus, using a large protrusion 1121 to reinforce the small pressure relief mechanism 6 not only results in material waste, but may also result in a weak pressure relief capability of the battery cell 10.

[0185] However, in this embodiment, W1×W2≥0.3mm 2 , which can improve the fatigue strength of the pressure relief mechanism 6; W1×W2≤100mm 2 , which can not only reduce material waste, but also improve the pressure relief capability of the battery cell 10 .

[0186] In some embodiments, 1 mm 2 ≤W1×W2≤20mm 2 .

[0187] In this embodiment, W1×W2 can be 1mm 2 , 2mm 2 , 3mm 2 , 4mm 2 , 5mm 2 , 6mm 2 , 7mm 2 , 8mm 2 , 9mm 2 , 10mm 2 , 11mm 2 , 12mm 2 , 13mm 2 , 14mm 2 , 15mm 2 , 16mm 2 , 17mm 2 , 18mm 2 , 19mm 2 , 20mm 2 Any point value or any range of values ​​between the two.

[0188] In some embodiments, referring to Figures 10-12, the housing 11 further includes a third wall portion 113 (shown in Figures 5 and 6), wherein the first wall portion 111, the second wall portion 112, and the third wall portion 113 are adjacent and connected in pairs, the first wall portion 111 is located on one side of the second wall portion 112 (shown in Figures 5 and 6) along the first direction Y, and the third wall portion 113 is located on one side of the second wall portion 112 along the second direction Z. The first direction Y, the second direction Z, and the thickness direction X of the electrode assembly intersect in pairs. Along the second direction Z, the protrusion 1121 has opposing third and fourth ends 11212 and 11213, and the pressure relief mechanism 6 is located between the third and fourth ends 11212 and 11213.

[0189] In the housing 11, the second wall portion 112 may be one or more, and the third wall portion 113 may be one or more. As an example, the housing 11 may include two second wall portions 112 and two third wall portions 113. The two second wall portions 112 are arranged opposite each other along the thickness direction X of the electrode assembly, and the two third wall portions 113 are arranged opposite each other along the second direction Z. The two second wall portions 112 and the two third wall portions 113 surround the first wall portion 111. The third wall portion 113 is connected to the first wall portion 111 via a second corner portion 115, and the third wall portion 113 is connected to the second wall portion 112 via a third corner portion 116. The second corner portion 115 and the third corner portion 116 are located at the corners of the housing 11. The cross-sections of the second corner portion 115 and the third corner portion 116 may be arc-shaped. The outer and inner surfaces of the second corner portion 115 and the outer and inner surfaces of the third corner portion 116 may be arc-shaped. The outer surface 1131 of the third wall portion smoothly transitions to the outer surface 1111 of the first wall portion via the outer surface of the second corner portion 115. The inner surface of the third wall portion 113 smoothly transitions to the inner surface of the first wall portion 111 via the inner surface of the second corner portion 115. The outer surface 1131 of the third wall portion smoothly transitions to the outer surface 1124 of the second wall portion via the outer surface of the third corner portion 116. The inner surface of the third wall portion 113 smoothly transitions to the inner surface of the second wall portion 112 via the inner surface of the third corner portion 116. The first wall portion 111, the second wall portion 112, and the third wall portion 113 can be integrally formed.

[0190] Any two of the first direction Y, the second direction Z and the thickness direction X of the electrode assembly may be arranged at an acute angle, a right angle or an obtuse angle. As an example, the first direction Y, the second direction Z and the thickness direction X of the electrode assembly are perpendicular to each other.

[0191] It can be understood that, when observed along the first direction Y, both ends of the protrusion 1121 along the second direction Z extend beyond the pressure relief mechanism 6, that is, in the direction from the third end 11212 to the fourth end 11213, the fourth end 11213 extends beyond the pressure relief mechanism 6, and in the direction from the fourth end 11213 to the third end 11212, the third end 11212 extends beyond the pressure relief mechanism 6.

[0192] As an example, in Figure 10, the size of the portion of the protrusion 1121 located on the second wall portion 112 along the thickness direction X of the electrode assembly is uniform, that is, the size of the portion of the protrusion 1121 located on the second wall portion 112 along the thickness direction X of the electrode assembly does not change in the second direction Z.

[0193] As an example, in FIG. 11 , the size of the portion of the protrusion 1121 located on the second wall portion 112 along the thickness direction X of the electrode assembly gradually decreases from the middle to both ends in the second direction Z.

[0194] As an example, in FIG. 12 , the size of the portion of the protrusion 1121 located on the second wall portion 112 along the thickness direction X of the electrode assembly gradually increases from the middle to both ends in the second direction Z.

[0195] In this embodiment, in this embodiment, the pressure relief mechanism 6 is located between the third end 11212 and the fourth end 11213 along the second direction Z, so that the pressure relief mechanism 6 is located within the effective reinforcement range of the protrusion 1121 in the second direction Z, so that the protrusion 1121 can play a better reinforcement role on the entire area of ​​the first wall portion 111 where the pressure relief mechanism 6 is set, further improving the fatigue resistance of the pressure relief mechanism 6.

[0196] In some embodiments, referring to Figures 10-12 , along the second direction Z, third wall portions 113 (shown in Figures 5 and 6 ) are provided on both sides of the second wall portion 112. The minimum distance between the third end 11212 and the outer surface 1131 of one third wall portion is A1, the minimum distance between the fourth end 11213 and the outer surface 1131 of the other third wall portion is A2, and the minimum distance between the outer surfaces 1131 of the two third wall portions is A, satisfying the following: |(A1-A2) / A|≤0.2.

[0197] Along the second direction Z, the distance between the two closest points between the end surface of the third end 11212 and the outer surface 1131 of one third wall portion is the minimum distance between the third end 11212 and the outer surface 1131 of one third wall portion. The distance between the two closest points between the end surface of the fourth end 11213 and the outer surface 1131 of the other third wall portion is the minimum distance between the fourth end 11213 and the outer surface 1131 of the other third wall portion. The distance between the two closest points on the outer surfaces 1131 of two third wall portions is the minimum distance between the outer surfaces 1131 of the two third walls. As an example, the outer surfaces 1131 of the two third walls are arranged in parallel.

[0198] |(A1-A2) / A| can be any point value among 0, 0.03, 0.05, 0.08, 0.1, 0.13, 0.15, 0.18, 0.2, etc., or a range of values ​​between any two points. A1 can be equal to, greater than, or less than A2.

[0199] Along the second direction Z, the middle area of ​​the first wall portion 111 is most likely to deform. However, 0≤|(A1-A2) / A|≤0.2, so that the protrusion 1121 is more centered in the second direction Z. The protrusion 1121 can better reinforce the middle area of ​​the first wall portion 111, thereby improving the deformation resistance of the middle area of ​​the first wall portion 111 and further improving the fatigue strength of the pressure relief mechanism 6.

[0200] In some embodiments, |(A1-A2) / A|≤0.05.

[0201] |(A1-A2) / A| can be any point value among 0, 0.01, 0.02, 0.03, 0.04, 0.05, etc., or a range of values ​​between any two points.

[0202] In this embodiment, |(A1-A2) / A|≤0.05, which further reduces the distance between the midpoint of the protrusion 1121 in the second direction Z and the midpoint of the second wall portion 112 in the second direction Z, so that the protrusion 1121 has a good reinforcing effect on the middle area of ​​the second wall portion 112, further enhancing the reinforcing effect of the protrusion 1121 on the middle area of ​​the first wall portion 111.

[0203] In some embodiments, please refer to Figures 13 and 14. Figure 13 is a YZ cross-sectional view of the housing 11 provided in some embodiments of the present application; Figure 14 is a schematic diagram of the connection between the protrusion 1121 and the second wall portion 112 provided in some embodiments of the present application. Along the thickness direction X of the electrode assembly, the second wall portion 112 includes an overlapping region 1125 that overlaps with the protrusion 1121 and a non-overlapping region 1126 that does not overlap with the protrusion 1121. The overlapping region 1125 and the protrusion 1121 together form a thickened region 1127. The maximum thickness of the thickened region 1127 is greater than the maximum thickness of the non-overlapping region 1126.

[0204] The overlapping region 1125 is the region where the second wall portion 112 and the protrusion 1121 overlap along the thickness direction X of the electrode assembly. The non-overlapping region 1126 is the region where the second wall portion 112 and the protrusion 1121 do not overlap along the thickness direction X of the electrode assembly. The non-overlapping region 1126 may be the portion of the second wall portion 112 excluding the overlapping region 1125. The thickness of the overlapping region 1125 and the thickness of the non-overlapping region 1126 may be equal or different. As an example, the inner surface of the overlapping region 1125 is flush with the inner surface of the non-overlapping region 1126, and the portion of the thickened region 1127 that extends beyond the outer surface of the non-overlapping region 1126 is the protrusion 1121.

[0205] In this embodiment, the protrusion 1121 can be formed by thickening a local area of ​​the second wall portion 112 , thereby reducing the difficulty of forming the protrusion 1121 .

[0206] In some embodiments, please continue to refer to FIG. 14 , the protrusion 1121 is disposed on the outer surface 1124 of the second wall portion.

[0207] The surface of the second wall portion 112 facing the outside of the housing 11 along its thickness direction is the second wall portion outer surface 1124. As an example, the thickness direction of the second wall portion 112 is parallel to the thickness direction X of the electrode assembly, and the protrusion 1121 is integrally formed with the second wall portion 112.

[0208] In this embodiment, the protrusion 1121 is disposed on the outer surface 1124 of the second wall portion. The protrusion 1121 does not need to occupy the space inside the shell 11 , thereby freeing up more space for the electrode assembly 2 .

[0209] In some embodiments, please continue to refer to FIG. 13 , the housing 11 has an opening, and the opening is disposed opposite to the first wall portion 111 .

[0210] As an example, the first wall portion 111 may be the wall portion at the bottom of the housing 11 and is used to support the electrode assembly 2 (not shown in FIG13 ). The thickness of the second wall portion 112 and the thickness of the third wall portion 113 are both smaller than the thickness of the first wall portion 111 .

[0211] In this embodiment, the pressure relief mechanism 6 is provided on the first wall portion 111 of the shell 11 opposite to the opening, so as to achieve pressure relief from the bottom of the shell 11 , thereby facilitating the discharge of emissions generated by thermal runaway of the battery cell 10 from the inside of the shell 11 .

[0212] In some embodiments, along the thickness direction X of the electrode assembly, second wall portions 112 are provided on both sides of the first wall portion 111 (shown in FIG. 8 and FIG. 9 ).

[0213] It can be understood that the two second wall portions 112 located on both sides of the first wall portion 111 are both provided with protrusions 1121 .

[0214] As an example, as shown in FIG13 , the third wall portions 113 are provided on both sides of the first wall portion 111 along the second direction Z. The two second wall portions 112 and the two third wall portions 113 are provided around the first wall portion 111 .

[0215] The protrusions 1121 on the second wall portion 112 on both sides of the first wall portion 111 can strengthen the first wall portion 111, further reducing the deformation of the first wall portion 111 when the electrode assembly 2 expands, and further improving the fatigue strength of the pressure relief mechanism 6.

[0216] In some embodiments, please refer to FIG15 , which is a partial view of the first wall portion 111 provided in some embodiments of the present application. The first wall portion 111 is provided with a first groove 61 to form a corresponding pressure relief mechanism 6 . The first wall portion 111 is configured to rupture along the first groove 61 to release the pressure inside the battery cell 10 .

[0217] The first groove 61 can be provided on the inner surface of the first wall portion 111 or on the outer surface 1111 of the first wall portion. The first groove 61 can extend along a closed trajectory, such as a circular trajectory, a rectangular trajectory, or an elliptical trajectory. The first groove 61 can also extend along a non-closed trajectory, such as a straight trajectory, an arc-shaped trajectory, a U-shaped trajectory, an H-shaped trajectory, or a V-shaped trajectory. The first groove 61 can be formed in the first wall portion 111 by laser etching, milling, stamping, or other methods.

[0218] The remaining portion of the first wall portion 111 in the area where the first groove 61 is provided serves as the pressure relief mechanism 6. The thickness of the remaining portion of the first wall portion 111 in the area where the first groove 61 is provided is less than the thickness of other areas of the first wall portion 111. After the first groove 61 is formed in the first wall portion 111, the pressure relief mechanism 6 can be formed integrally with the first wall portion 111 in the area of ​​the first groove 61.

[0219] In this embodiment, the pressure relief mechanism 6 is formed by providing a first groove 61 in the first wall portion 111. This simple molding method facilitates control of the burst pressure of the pressure relief mechanism 6. This integrally formed structure of the pressure relief mechanism 6 and the first wall portion 111 provides enhanced structural stability. When the first groove 61 is stamped, excess material corresponding to the first groove 61 can diffuse along the thickness direction X of the electrode assembly during the stamping process, thereby thickening a local area of ​​the second wall portion 112 and forming a reinforcement.

[0220] In some embodiments, please continue to refer to Figure 15, the first slot 61 may include a first slot segment 611, a second slot segment 612 and a third slot segment 613, the first slot segment 611 and the third slot segment 613 are arranged opposite to each other, and the second slot segment 612 connects the first slot segment 611 and the third slot segment 613.

[0221] The first slot segment 611, the second slot segment 612, and the third slot segment 613 can be linear slots extending along a straight line, or non-linear slots extending along a non-straight line, for example, arcuate slots extending along an arcuate line. If the first slot segment 611, the second slot segment 612, and the third slot segment 613 are linear slots, the first slot segment 611 and the third slot segment 613 can be arranged parallel to each other, or at an acute or obtuse angle. The first slot segment 611 and the second slot segment 612 can be arranged perpendicularly, or at an acute or obtuse angle; the third slot segment 613 and the second slot segment 612 can be arranged perpendicularly, or at an acute or obtuse angle.

[0222] The second trough section 612 is connected to the first trough section 611 and the third trough section 613. The two ends of the second trough section 612 may be connected to the first trough section 611 and the third trough section 613, respectively. Alternatively, at least one of the first trough section 611 and the third trough section 613 may be connected to a position offset from the end of the second trough section 612, such that at least one of the first trough section 611 and the third trough section 613 is located between the two ends of the second trough section 612. The first trough section 611, the second trough section 612, and the third trough section 613 may be formed in various shapes, such as a U-shape, an N-shape, an H-shape, etc.

[0223] The first slot segment 611 and the second slot segment 612 are connected at a first position 614. The first position 614 can be located at one end of the first slot segment 611 or offset from both ends of the first slot segment 611. The third slot segment 613 and the second slot segment 612 are connected at a second position 615. The second position 615 can be located at one end of the third slot segment 613 or offset from both ends of the third slot segment 613. As an example, the first position 614 is located at the midpoint of the first slot segment 611, and the second position 615 is located at the midpoint of the third slot segment 613.

[0224] Along the thickness direction X of the electrode assembly, the minimum distance between the first slot segment 611 or the third slot segment 613, whichever is closer to the outer surface 1124 of the second wall, and the outer surface 1124 of the second wall, is the minimum distance W2 between the pressure relief mechanism 6 and the outer surface 1124 of the second wall. As an example, the minimum distance between the first slot segment 611 and the outer surface 1124 of the second wall and the minimum distance between the third slot segment 613 and the outer surface 1124 of the second wall are equal, both being W2.

[0225] When the battery cell 10 thermally runs away, the first wall portion 111 can be cracked along the first groove section 611, the second groove section 612 and the third groove section 613, so that the area defined by the first groove section 611, the second groove section 612 and the third groove section 613 can be opened outward to release pressure, so that the pressure relief mechanism 6 has a larger pressure relief area.

[0226] In some embodiments, referring to Figures 16-18, Figure 16 is a cross-sectional view taken along line BB of the first wall portion 111 shown in Figure 15; Figure 17 is a partial enlarged view of point C of the first wall portion 111 shown in Figure 16; and Figure 18 is a partial enlarged view of point D of the first wall portion 111 shown in Figure 16. The residual thickness of the first slot segment 611 and the residual thickness of the third slot segment 613 are both less than the residual thickness of the second slot segment 612.

[0227] The residual thickness of the first slot segment 611 is the thickness of the remaining portion after the first slot segment 611 is provided on the first wall portion 111. The remaining portion may be the slot bottom wall of the first slot segment 611. The thickness of the slot bottom wall of the first slot segment 611 may be uniform or uneven. If the thickness of the slot bottom wall of the first slot segment 611 is uneven, the thickness of the thinnest portion of the slot bottom wall of the first slot segment 611 is the residual thickness of the first slot segment 611. The residual thickness of the second slot segment 612 is the thickness of the remaining portion after the second slot segment 612 is provided on the first wall portion 111. The remaining portion may be the slot bottom wall of the second slot segment 612. The thickness of the slot bottom wall of the second slot segment 612 may be uniform or uneven. If the thickness of the slot bottom wall of the second slot segment 612 is uneven, the thickness of the thinnest portion of the slot bottom wall of the second slot segment 612 is the residual thickness of the second slot segment 612. The residual thickness of the third slot segment 613 is the thickness of the remaining portion of the first wall portion 111 after the third slot segment 613 is provided. This remaining portion may be the bottom wall of the third slot segment 613. The thickness of the bottom wall of the third slot segment 613 may be uniform or non-uniform. If the thickness of the bottom wall of the third slot segment 613 is non-uniform, the thickness of the thinnest portion of the bottom wall of the third slot segment 613 is considered the residual thickness of the third slot segment 613.

[0228] As an example, the depth of the first slot segment 611 is greater than the depth of the second slot segment 612, so that the residual thickness of the first slot segment 611 is smaller than the residual thickness of the second slot segment 612. The depth of the third slot segment 613 is greater than the depth of the second slot segment 612, so that the residual thickness of the third slot segment 613 is smaller than the residual thickness of the second slot segment 612.

[0229] As shown in Figures 17 and 18, the residual thickness of the first slot segment 611 is D1, the residual thickness of the second slot segment 612 is D2, and the residual thickness of the third slot segment 613 is D3. It can be understood that D1 < D2, D3 < D2. D1 and D3 can be equal or different.

[0230] Continuing with Figure 15 , the first groove section 611 can be located near the first position 614, forming its weakest point. The third groove section 613 can be located near the second position 615, forming its weakest point. When the battery cell 10 is depressurized, after the first wall portion 111 cracks at the weakest points of the first and third groove sections 611 and 613, the cracks will propagate along the first and third groove sections 611 and 613, and also along the second groove section 612. This shortens the time it takes for the first wall portion 111 to crack along the first groove 61, improving the timeliness of pressure relief. Furthermore, at least one of the weakest points of the first and third groove sections 613 can serve as the initial rupture point of the first wall portion 111 during pressure relief. When the internal pressure of the battery cell 10 reaches the bursting pressure, the first wall portion 111 initially ruptures at the initial rupture point.

[0231] In this embodiment, the residual thickness of the first groove section 611 and the residual thickness of the third groove section 613 are both smaller than the residual thickness of the second groove section 612, which is equivalent to increasing the residual thickness of the second groove section 612, thereby improving the fatigue strength of the first wall portion 111 in the area where the second groove section 612 is set, reducing the risk of the first wall portion 111 cracking at the position of the second groove section 612 during normal use of the battery cell 10, improving the long-term reliability of the pressure relief mechanism 6, and increasing the service life of the battery cell 10.

[0232] In some embodiments, referring to FIG. 17 , the residual thickness of the first slot segment 611 is D1 , and the residual thickness of the second slot segment 612 is D2 , satisfying the following relationship: 0.15≤D1 / D2≤0.95.

[0233] D1 / D2 can be any point value among 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, etc., or a range value between any two of them.

[0234] The inventors conducted multiple tests, in which the D2 of the battery cells 10 in different groups was different. The explosion rate of the battery cells 10 in each group during thermal runaway and the cracking rate of the first wall portion 111 along the second groove section 612 under normal use conditions of the battery cells 10 were measured. The test results are shown in Table 1.

[0235] The method for measuring the residual thickness of the first groove segment 611 and the residual thickness of the third groove segment 613 is as follows: the first wall portion 111 is cut into three sections, and the cutting direction is perpendicular to the extension direction of the first groove segment 611. The cross section of the middle section is polished to fully remove burrs and then placed on a three-dimensional coordinate measuring machine. The residual thickness of the first groove segment 611 and the residual thickness of the third groove segment 613 on the cross section are measured by the three-dimensional coordinate measuring machine.

[0236] Method for measuring the residual thickness of the second groove segment 612: cut the above-mentioned middle segment into three segments, with the cutting direction perpendicular to the extension direction of the second groove segment 612, polish the cross section of the middle segment among the three segments to fully remove burrs, and then place it on a three-dimensional coordinate measuring machine, and measure the residual thickness of the second groove segment 612 on the cross section using the three-dimensional coordinate measuring machine.

[0237] The explosion rate of battery cells 10 during thermal runaway is measured by heating the battery cells 10 until thermal runaway occurs and observing whether the battery cells 10 explode. Each test uses 1,000 battery cells 10, and the explosion rate is calculated: explosion rate Q1 = number of exploded battery cells 10 / total number of battery cells 10 × 100%.

[0238] Method for measuring the cracking rate of the first wall portion 111 along the second groove section 612 under normal use conditions of the battery cell 10: place the battery cell 10 at 25±2°C and perform cyclic charge and discharge in the charge and discharge range of 5%-97% SOC. Conduct 1000 sets of tests to observe whether the first wall portion 111 cracks along the second groove section 612 when the battery cell 10 life drops to 80% SOH. Count the cracking rate of the first wall portion 111 along the second groove section 612, and the cracking rate Q2 = the number of cracked battery cells 10 / the total number of battery cells 10 × 100%.

[0239] Table 1

[0240] It can be seen from Table 1 above that 0.15≤D1 / D2≤0.95, which can not only improve the timeliness of pressure release of the battery cell 10 but also increase the service life of the battery cell 10 , and take into account both the timeliness and reliability of pressure release of the pressure release mechanism 6 .

[0241] In some embodiments, 0.5≤D1 / D2≤0.85.

[0242] In this embodiment, D1 / D2 can be any one of the point values ​​of 0.5, 0.52, 0.53, 0.55, 0.57, 0.58, 0.59, 0.6, 0.62, 0.63, 0.65, 0.67, 0.68, 0.69, 0.7, 0.72, 0.73, 0.75, 0.77, 0.78, 0.79, 0.8, 0.82, 0.83, 0.85, etc., or a range value between any two of them.

[0243] As can be seen from Table 1 above, when 0.5≤D1 / D2≤0.85, the overall performance of the battery cell 10 is further improved. This can not only control the probability of the first wall portion 111 cracking along the second groove section 612 during normal use of the battery cell 10 to a low level, but also control the probability of the battery cell 10 exploding during thermal runaway to a low level.

[0244] In some embodiments, the residual thickness of the third slot segment 613 is D3, which satisfies the following: 0.15≤D3 / D2≤0.95.

[0245] D3 / D2 can be any point value of 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, etc., or a range of values ​​between any two of them.

[0246] It can be seen from Table 1 above that 0.15≤D3 / D2≤0.95, which can not only improve the timeliness of pressure release of the battery cell 10 but also increase the service life of the battery cell 10 , and take into account both the timeliness and reliability of pressure release of the pressure release mechanism 6 .

[0247] In some embodiments, 0.5≤D3 / D2≤0.85.

[0248] In this embodiment, D3 / D2 can be any one of the point values ​​of 0.5, 0.52, 0.53, 0.55, 0.57, 0.58, 0.59, 0.6, 0.62, 0.63, 0.65, 0.67, 0.68, 0.69, 0.7, 0.72, 0.73, 0.75, 0.77, 0.78, 0.79, 0.8, 0.82, 0.83, 0.85, etc., or a range value between any two of them.

[0249] As can be seen from Table 1 above, when 0.5≤D3 / D2≤0.85, the overall performance of the battery cell 10 is further improved. This can not only control the probability of the first wall portion 111 cracking along the second groove section 612 during normal use of the battery cell 10 to a low level, but also control the probability of the battery cell 10 exploding during thermal runaway to a low level.

[0250] In some embodiments, referring to FIG. 19 , which is a partial view of the first wall portion 111 provided in other embodiments of the present application, the first slot 61 further includes at least one fourth slot segment 616. The fourth slot segment 616 is located between the first slot segment 611 and the third slot segment 613 and is connected to the second slot segment 612. The residual thickness of the first slot segment 611 and the residual thickness of the third slot segment 613 are both less than the residual thickness of the fourth slot segment 616.

[0251] The fourth slot segment 616 in the first slot 61 can be one or more. The fourth slot segment 616 can be a linear slot extending along a linear trajectory, or a non-linear slot extending along a non-linear trajectory. For example, the fourth slot segment 616 is an arcuate slot extending along an arcuate trajectory. If the fourth slot segment 616 is a linear slot, the fourth slot segment 616 and the second slot segment 612 can be perpendicular, or can be arranged at an acute angle or an obtuse angle. The connection position between the fourth slot segment 616 and the second slot segment 612 can be located at one end of the fourth slot segment 616, for example, the fourth slot segment 616 and the second slot segment 612 form a "T" structure; the connection position between the fourth slot segment 616 and the second slot segment 612 can also deviate from the two ends of the fourth slot segment 616, for example, the fourth slot segment 616 and the second slot segment 612 form a "X" structure.

[0252] The residual thickness of the fourth slot segment 616 is the thickness of the remaining portion after the fourth slot segment 616 is provided on the first wall portion 111. This remaining portion may be the bottom wall of the fourth slot segment 616. The thickness of the bottom wall of the fourth slot segment 616 may be uniform or non-uniform. If the thickness of the bottom wall of the fourth slot segment 616 is non-uniform, the thickness of the thinnest portion of the bottom wall of the fourth slot segment 616 is considered the residual thickness of the fourth slot segment 616.

[0253] As an example, in FIG19 , the first slot segment 611 , the second slot segment 612 , the third slot segment 613 and the fourth slot segment 616 are all straight slots, and the first slot segment 611 , the third slot segment 613 and the fourth slot segment 616 are all perpendicular to the second slot segment 612 .

[0254] In this embodiment, since the residual thickness of the second slot segment 612 is smaller than the residual thickness of the first slot segment 611 and the residual thickness of the third slot segment 613, the second slot segment 612 is more difficult to crack than the first slot segment 611 and the third slot segment 613. After the fourth slot segment 616 is provided, the stress at the position where the second slot segment 612 and the fourth slot segment 616 are connected is more concentrated, forming a stress concentration point, which weakens the strength of the second slot segment 612 at this position, making it more susceptible to damage, thereby reducing the difficulty of the first wall portion 111 cracking along the second slot segment 612. Because the residual thickness of the first slot segment 611 and the residual thickness of the third slot segment 613 are both smaller than the residual thickness of the fourth slot segment 616, the location where the fourth slot segment 616 connects to the second slot segment 612 is less likely to crack than the location where the first slot segment 611 connects to the second slot segment 612 and the location where the third slot segment 613 connects to the second slot segment 612. This reduces the possibility of the first wall portion 111 being deformed by external forces during normal use of the battery cell 10, thereby increasing the service life of the battery cell 10.

[0255] In some embodiments, please continue to refer to FIG. 15 and FIG. 19 , along the extension direction of the second slot segment 612 , both ends of the second slot segment 612 are connected to the first slot segment 611 and the third slot segment 613 respectively.

[0256] One end of the second slot segment 612 is connected to the first slot segment 611 at a first position 614 , and the other end of the second slot segment 612 is connected to the third slot segment 613 at a second position 615 .

[0257] In this embodiment, the two ends of the second slot segment 612 are respectively connected to the first slot segment 611 and the third slot segment 613, so that the two ends of the second slot segment 612 do not extend beyond the first slot segment 611 and the third slot segment 613 respectively. During the pressure relief process, the pressure can be accurately relieved through the area defined by the first slot segment 611, the second slot segment 612 and the third slot segment 613, which is less likely to cause cracking and pressure relief in other areas of the first wall portion 111, and it is easier to achieve directional pressure relief.

[0258] In some embodiments, please continue to refer to FIG. 15 and FIG. 19 , the first slot segment 611 , the second slot segment 612 , and the third slot segment 613 are all slots extending along a straight line.

[0259] The first slot section 611, the second slot section 612, and the third slot section 613 are all linear slots. The first slot section 611 and the second slot section 612 can be perpendicular, or they can be arranged at an acute angle or an obtuse angle. The third slot section 613 and the second slot section 612 can be perpendicular, or they can be arranged at an acute angle or an obtuse angle. The lengths of the first slot section 611 and the third slot section 613 can be equal or unequal. As an example, the first slot section 611 and the third slot section 613 are both perpendicular to the second slot section 612, and the first slot section 611 and the third slot section 613 are equal in length.

[0260] In this embodiment, the first slot segment 611 , the second slot segment 612 and the third slot segment 613 are all linear slots, which can reduce the difficulty of forming the first slot segment 611 , the second slot segment 612 and the third slot segment 613 .

[0261] In some embodiments, the first wall portion 111 is a rectangular wall portion, the second slot segment 612 extends along the length direction of the first wall portion 111 , and the first slot segment 611 and the third slot segment 613 both extend along the width direction of the first wall portion 111 .

[0262] The length of the first wall portion 111 is greater than the width of the first wall portion 111 , and the first slot segment 611 and the third slot segment 613 are both perpendicular to the second slot segment 612 .

[0263] In this embodiment, the second slot section 612 extends along the length direction of the first wall portion 111. The first wall portion 111 can provide more space for the second slot section 612, and the second slot section 612 can be made longer, thereby increasing the pressure relief area of ​​the pressure relief mechanism 6.

[0264] In some embodiments, please refer to Figures 20-22. Figure 20 is a schematic structural diagram of a battery cell 10 provided in other embodiments of the present application; Figure 21 is a partial enlarged view of point D in Figure 20; and Figure 22 is a partial view of the first wall portion 111 shown in Figure 21. The first wall portion 111 is provided with a second groove 62. The second groove 62 and the first groove 61 are arranged along the thickness direction of the first wall portion 111. The second groove 62 includes a fifth groove segment 621, a sixth groove segment 622, and a seventh groove segment 623. The fifth groove segment 621 and the seventh groove segment 623 are arranged opposite each other, and the sixth groove segment 622 connects the fifth groove segment 621 and the seventh groove segment 623. The first groove segment 611 is provided on the groove bottom surface of the fifth groove segment 621, the second groove segment 612 is provided on the groove bottom surface of the sixth groove segment 622, and the third groove segment 613 is provided on the groove bottom surface of the seventh groove segment 623.

[0265] The thickness direction of the first wall portion 111 can be parallel to the first direction Y. The fifth slot segment 621 can extend in the same direction as the first slot segment 611, the sixth slot segment 622 can extend in the same direction as the second slot segment 612, and the seventh slot segment 623 can extend in the same direction as the third slot segment 613, so that the shape of the second slot 62 is substantially the same as that of the first slot 61. The slot width of the fifth slot segment 621 is greater than that of the first slot segment 611, the slot width of the sixth slot segment 622 is greater than that of the second slot segment 612, and the slot width of the seventh slot segment 623 is greater than that of the third slot segment 613. As an example, the slot bottom surfaces of the fifth slot segment 621, the sixth slot segment 622, and the seventh slot segment 623 are coplanar.

[0266] In an embodiment where the first groove 61 further includes a fourth groove segment 616, as shown in FIG22 , the groove side surface of the sixth groove segment 622 at a position corresponding to the fourth groove segment 616 can be recessed to form a first recess 624 to provide a molding space for the fourth groove segment 616. The wall surface of the first recess 624 can be an arc surface. As an example, the radius of the wall surface of the first recess 624 is 0.5 mm to 2 mm.

[0267] The first groove section 611, the second groove section 612 and the third groove section 613 are respectively arranged on the groove bottom surfaces of the fifth groove section 621, the sixth groove section 622 and the seventh groove section 623, so that the groove sections in the second groove 62 correspond to the groove sections in the first groove 61. When the bursting pressure of the pressure relief mechanism 6 is constant, the depths of the first groove section 611, the second groove section 612 and the third groove section 613 can be reduced, thereby reducing the risk of damage to the first wall portion 111 during the formation of the first groove 61.

[0268] In some embodiments, please refer to FIG23 and FIG24. FIG23 is a partial view of a battery cell 10 provided in some other embodiments of the present application; FIG24 is a partial view of the first wall portion 111 shown in FIG23. The first wall portion 111 is provided with a third groove 63. The third groove 63, the second groove 62, and the first groove 61 are arranged along the thickness direction of the first wall portion 111. The third groove 63 includes an eighth groove segment 631, a ninth groove segment 632, and a tenth groove segment 633. The eighth groove segment 631 and the tenth groove segment 633 are arranged opposite each other, and the ninth groove segment 632 connects the eighth groove segment 631 and the tenth groove segment 633. Among them, the fifth groove segment 621 is provided on the groove bottom surface of the eighth groove segment 631, the sixth groove segment 622 is provided on the groove bottom surface of the ninth groove segment 632, and the seventh groove segment 623 is provided on the groove bottom surface of the tenth groove segment 633.

[0269] The eighth slot segment 631 can extend in the same direction as the fifth slot segment 621, the ninth slot segment 632 can extend in the same direction as the sixth slot segment 622, and the tenth slot segment 633 can extend in the same direction as the seventh slot segment 623, so that the shape of the third slot 63 is substantially the same as the shape of the second slot 62. The slot width of the eighth slot segment 631 is greater than the slot width of the fifth slot segment 621, the slot width of the ninth slot segment 632 is greater than the slot width of the sixth slot segment 622, and the slot width of the tenth slot segment 633 is greater than the slot width of the seventh slot segment 623. As an example, the slot bottom surfaces of the eighth slot segment 631, the ninth slot segment 632, and the tenth slot segment 633 are coplanar.

[0270] As an example, as shown in FIG24 , the groove side surface of the ninth groove segment 632 may be recessed at a position corresponding to the first recess 624 to form a second recess 634, thereby providing a molding space for the first recess 624. The wall surface of the second recess 634 and the wall surface of the first recess 624 may both be arcuate surfaces, and the radius of the wall surface of the second recess 634 is greater than the radius of the wall surface of the first recess 624.

[0271] In this embodiment, the fifth groove segment 621, the sixth groove segment 622 and the seventh groove segment 623 are respectively arranged on the groove bottom surfaces of the eighth groove segment 631, the ninth groove segment 632 and the tenth groove segment 633, so that the groove segments in the third groove 63 correspond to the groove segments in the second groove 62, which can reduce the depth of the fifth groove segment 621, the sixth groove segment 622 and the seventh groove segment 623, and reduce the risk of damage to the first wall portion 111 during the forming process of the second groove 62.

[0272] In some embodiments, please refer to FIG25 , which is a partial view of the first wall portion 111 provided in some further embodiments of the present application. The first slot segment 611 has a first midplane 6111 extending along its extension direction, the second slot segment 612 has a second midplane 6121 extending along its extension direction, and the third slot segment 613 has a third midplane 6131 extending along its extension direction. The minimum distance from the center point 1111a of the outer surface 1111 of the first wall portion to the first midplane 6111 is M1, the minimum distance from the center point 1111a of the outer surface 1111 of the first wall portion to the second midplane 6121 is M2, and the minimum distance from the center point 1111a of the outer surface 1111 of the first wall portion to the third midplane 6131 is M3, satisfying the following conditions: M2 < M1, M2 < M3.

[0273] Among them, M1 can be M3, M1<M3, or M1>M3.

[0274] The outer surface 1111 of the first wall portion is the surface of the first wall portion 111 that faces away from the interior of the housing 11; that is, the outer surface 1111 of the first wall portion faces the exterior of the housing 1. Along the thickness direction of the first wall portion 111, the first wall portion 111 also has an inner surface that faces the interior of the housing 1. The first groove section 611, the second groove section 612, and the third groove section 613 can all be recessed in a direction from the outer surface 1111 of the first wall portion toward the inner surface of the first wall portion 111, or can be recessed in a direction from the inner surface of the first wall portion 111 toward the outer surface 1111 of the first wall portion.

[0275] The center point 1111a of the outer surface 1111 of the first wall is the geometric center of the outer surface 1111 of the first wall. The outer surface 1111 of the first wall can be circular, polygonal, etc. The polygon can be a triangle, quadrilateral, pentagon, hexagon, etc.

[0276] The first midplane 6111 is aligned with the direction in which the first slot segment 611 extends. In the width direction of the first slot segment 611, the first midplane 6111 is centered on the first slot segment 611 and is perpendicular to the width direction of the first slot segment 611. The second midplane 6121 is aligned with the direction in which the second slot segment 612 extends. In the width direction of the second slot segment 612, the second midplane 6121 is centered on the second slot segment 612 and is perpendicular to the width direction of the second slot segment 612. The third midplane 6131 is aligned with the direction in which the third slot segment 613 extends. In the width direction of the third slot segment 613, the third midplane 6131 is centered on the third slot segment 613 and is perpendicular to the width direction of the third slot segment 613.

[0277] The minimum distance from the center point 1111a of the first wall's outer surface 1111 to the first midplane 6111 can be measured on a perpendicular line to the first midplane 6111, which passes through the center point 1111a of the first wall's outer surface 1111. The minimum distance from the center point 1111a of the first wall's outer surface 1111 to the second midplane 6121 can be measured on a perpendicular line to the second midplane 6121, which passes through the center point 1111a of the first wall's outer surface 1111. The minimum distance from the center point 1111a of the first wall's outer surface 1111 to the third midplane 6131 can be measured on a perpendicular line to the third midplane 6131, which passes through the center point 1111a of the first wall's outer surface 1111.

[0278] When the internal pressure of the battery cell 10 changes, the closer the first wall portion 111 is to the center point 1111a, the easier it is to deform, and M2 < M1, M2 < M3, so that the first groove section 611 and the third groove section 613 are farther away from the center point 1111a, thereby improving the fatigue strength of the first wall portion 111 at the first groove section 611 and the third groove section 613.

[0279] In some embodiments, along the thickness direction of the first wall portion 111 , a projection of a center point 1111 a of the outer surface 1111 of the first wall portion is located within the second slot segment 612 ; and / or, |M3−M1|≦5 mm.

[0280] Along the thickness direction of the first wall portion 111, the projection of the center point 1111a is located within the second slot segment 612, that is, a perpendicular line to the outer surface 1111 of the first wall portion passing through the center point 1111a passes through the second slot segment 612. As an example, the center point 1111a of the outer surface 1111 of the first wall portion is located within the second midplane 6121.

[0281] |M3-M1| can be any point value among 0mm, 1mm, 2mm, 3mm, 4mm, 5mm, etc., or a range value between any two.

[0282] In this embodiment, the projection of the center point 1111a of the outer surface 1111 of the first wall portion is located within the second groove section 612. The second groove section 612 is closer to the center point 1111a of the outer surface 1111 of the first wall portion. This allows the first wall portion 111 to break more promptly along the second groove section 612 during pressure relief, thereby improving the timeliness of pressure relief for the first wall portion 111. The value |M3-M1|≤5mm ensures that both the first and third groove sections 611 and 613 are relatively far from the center point 1111a, reducing the impact of deformation of the first wall portion 111 near the center point 1111a on the first and third groove sections 611 and 613.

[0283] In some embodiments, please refer to FIG26 , which is a cross-sectional view of the first wall portion 111 provided in some embodiments of the present application. The first wall portion 111 is provided with a second groove 62 , and the first groove 61 is provided on the bottom surface of the second groove 62 .

[0284] The shape of the second groove 62 can be the same as that of the first groove 61. For example, both the second groove 62 and the first groove 61 are H-shaped grooves. The shapes of the second groove 62 and the first groove 61 can also be different. For example, the second groove 62 is a cylindrical groove or a prismatic groove, while the first groove 61 is an H-shaped groove. If the second groove 62 is a cylindrical groove, the interior space of the second groove 62 is generally cylindrical; if the second groove 62 is a prismatic groove, the interior space of the second groove 62 is generally prismatic. The prismatic groove can be a triangular prism groove, a quadrangular prism groove, a pentagonal prism groove, a hexagonal prism groove, etc.

[0285] The second groove 62 can be formed in a variety of ways, such as stamping, milling, laser etching, etc. For example, in the case where both the first groove 61 and the second groove 62 are stamped on the first wall portion 111, the second groove 62 can be stamped on the first wall portion 111, and then the first groove 61 can be stamped on the bottom surface of the second groove 62. As an example, in FIG26 , the second groove 62 is provided on the outer surface 1111 of the first wall portion.

[0286] Taking the example of an H-shaped first groove 61, the first groove segment 611, the second groove segment 612, and the third groove segment 613 in the first groove 61 are all disposed on the groove bottom surface of the second groove 62. In an embodiment where the first groove 61 also includes a fourth groove segment 616, the fourth groove segment 616 is also disposed on the groove bottom surface of the second groove 62. Taking the example of an H-shaped second groove 62, the first groove segment 611 can be disposed on the groove bottom surface of the fifth groove segment 621, the second groove segment 612 can be disposed on the groove bottom surface of the sixth groove segment 622, and the third groove segment 613 can be disposed on the groove bottom surface of the seventh groove segment 623, thereby achieving the arrangement of the first groove 61 on the groove bottom surface of the second groove 62.

[0287] In this embodiment, the provision of the second groove 62 can reduce the forming depth of the first groove 61 , reduce the forming force exerted on the first wall portion 111 when forming the first groove 61 , and reduce the possibility of cracks in the first wall portion 111 when forming the first groove 61 .

[0288] In some embodiments, please refer to FIG27 , which is a cross-sectional view of the first wall portion 111 provided in some other embodiments of the present application. The first wall portion 111 is provided with a third groove 63 , and the second groove 62 is provided at the bottom surface of the third groove 63 .

[0289] The first groove 61, the second groove 62, and the third groove 63 can be arranged along the thickness direction of the first wall portion 111. When forming the first groove 61, the second groove 62, and the third groove 63 on the first wall portion 111, the third groove 63 can be formed on the first wall portion 111 first, the second groove 62 can be formed on the bottom surface of the third groove 63, and finally the first groove 61 can be formed on the bottom surface of the second groove 62. As an example, in FIG. 27, the third groove 63 is provided on the outer surface 1111 of the first wall portion.

[0290] The third groove 63 can be a groove with the same shape as the second groove 62. For example, the second groove 62 is an H-shaped groove, and the third groove 63 is also an H-shaped groove. The third groove 63 can also be a groove with a different shape from the second groove 62. For example, the second groove 62 is an H-shaped groove, and the third groove 63 is a cylindrical groove or a prismatic groove. The third groove 63 can be formed in a variety of ways, such as stamping, milling, laser etching, etc. For example, the second groove 62 and the third groove 63 are both quadrangular prism grooves, the first groove 61 is an H-shaped groove, and the first groove 61, the second groove 62 and the third groove 63 are all formed on the first wall portion 111 by stamping. During the forming process, the third groove 63 in the shape of a quadrangular prism can be stamped on the first wall portion 111 first, and then the second groove 62 in the shape of a quadrangular prism can be stamped on the bottom surface of the third groove 63, and then the first groove 61 in the shape of an H can be stamped on the bottom surface of the second groove 62.

[0291] In this embodiment, the provision of the third groove 63 can reduce the forming depth of the second groove 62 , reduce the forming force exerted on the first wall portion 111 when forming the second groove 62 , and reduce the possibility of cracks in the first wall portion 111 when forming the second groove 62 .

[0292] In some embodiments, please refer to Figure 28, which is a schematic diagram of the structure of an electrode assembly 2 provided in some embodiments of the present application. The electrode assembly 2 is a laminated structure, and the stacking direction of the electrode sheets in the electrode assembly 2 is parallel to the thickness direction X of the electrode assembly.

[0293] As an example, the electrode assembly 2 may include a positive electrode sheet 22, a separator 23, and a negative electrode sheet 24, wherein the positive electrode sheet 22 and the negative electrode sheet 24 are stacked. The separator 23 is used to insulate and separate the positive electrode sheet 22 and the negative electrode sheet 24. The separator 23 may be a separator disposed between the positive electrode sheet 22 and the negative electrode sheet 24.

[0294] As an example, the negative electrode sheet 24 may include a bent section 241 and multiple stacked sections 242. Two adjacent stacked sections 242 are connected by the bent section 241, and a positive electrode sheet 22 is sandwiched between the two adjacent stacked sections 242. The stacked sections 242 and the positive electrode sheet 22 are stacked in a direction parallel to the thickness direction X of the electrode assembly. The stacked direction of the stacked sections 242 and the positive electrode sheet 22 is the stacking direction of the electrode sheets in the electrode assembly 2.

[0295] For the laminated electrode assembly 2, its expansion in the stacking direction of the pole pieces is greater. Since the stacking direction of the pole pieces is parallel to the thickness direction X of the electrode assembly, the second wall portion 112 is more affected by the expansion of the electrode assembly 2. Therefore, a protrusion 1121 is provided on the second wall portion 112 to directly strengthen the second wall portion 112 and indirectly strengthen the first wall portion 111, thereby effectively increasing the fatigue strength of the pressure relief mechanism 6.

[0296] In some embodiments, please refer to FIG. 29 , which is a schematic diagram of the structure of an electrode assembly 2 provided in other embodiments of the present application. The electrode assembly 2 is a wound structure, comprising a straight region 25 and a bent region 26 , wherein the bent region 26 is connected to the straight region 25 , and the stacking direction of the electrode sheets in the straight region 25 is parallel to the thickness direction X of the electrode assembly.

[0297] Bending regions 26 may be provided at both ends of the straight region 25, and the two bending regions 26 may be arranged along the second direction Z. The electrode assembly 2 may include a positive electrode sheet 22, a separator 23, and a negative electrode sheet 24, wherein the positive electrode sheet 22, the separator 23, and the negative electrode sheet 24 are wound to form a wound structure. The separator 23 is used to insulate and separate the positive electrode sheet 22 and the negative electrode sheet 24. The separator 23 may be a separator provided between the positive electrode sheet 22 and the negative electrode sheet 24. The portion of the positive electrode sheet 22 located in the straight region 25 and the portion of the negative electrode sheet 24 located in the straight region 25 are stacked, and the stacking direction is parallel to the thickness direction X of the electrode assembly, which is the stacking direction of the electrode sheets in the straight region 25. The portion of the positive electrode sheet 22 located in the straight region 25 and the portion of the negative electrode sheet 24 located in the straight region 25 are both in a straight state, and the portion of the positive electrode sheet 22 located in the bending region 26 and the portion of the negative electrode sheet 24 located in the bending region 26 are both in a bent state. As an example, the portion of the positive electrode sheet 22 located in the bending area 26 and the portion of the negative electrode sheet 24 located in the bending area 26 are both arc-shaped structures.

[0298] For the wound electrode assembly 2, the expansion amount of the electrode sheets in the straight area 25 in the stacking direction is greater. Since the stacking direction of the electrode sheets in the straight area 25 is parallel to the thickness direction X of the electrode assembly, the second wall portion 112 is more affected by the expansion of the electrode assembly 2. Therefore, a protrusion 1121 is provided on the second wall portion 112 to directly strengthen the second wall portion 112 and indirectly strengthen the first wall portion 111, thereby effectively increasing the fatigue strength of the pressure relief mechanism 6.

[0299] An embodiment of the present application provides a battery 100 , comprising the battery cell 10 provided in any one of the above embodiments.

[0300] An embodiment of the present application provides an electrical device, comprising 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.

[0301] In addition, an embodiment of the present application further provides a battery cell 10, comprising a housing 1 and an electrode assembly 2. The electrode assembly 2 is flat and housed within the housing 1. The housing 1 comprises a shell 11 and an end cap 12. The shell 11 has an opening formed at one end. The shell 11 is used to house the electrode assembly 2, and the end cap 12 seals the opening of the shell 11. The shell 11 comprises a first wall 111, two second walls 112, and two third walls 113. The first wall 111, the second wall 112, and the third wall 113 are adjacent to and connected to each other. The two second walls 112 and the two third walls 113 are arranged around the first wall 111. Along a first direction Y, the first wall 111 and the opening of the shell 11 are located at opposite ends of the shell 11, respectively. Along a thickness direction X of the electrode assembly, the two second walls 112 are arranged opposite each other. Along a second direction Z, the two third walls 113 are arranged opposite each other. The first direction Y, the second direction Z, and the thickness direction X of the electrode assembly are perpendicular to each other. The first wall portion 111 is provided with a first groove 61 corresponding to the pressure relief mechanism 6. The first groove 61 is an H-shaped groove. The second wall portion 112 is provided with a protrusion 1121 protruding from the outer surface 1124 of the second wall portion. The protrusion 1121 is used to strengthen the second wall portion 112 and the first wall portion 111.

[0302] Among them, the first wall portion 111 and the second wall portion 112 are connected through the first corner portion 114. Along the first direction Y, the first wall portion 111 has a first end 1122 and a second end 1123 that are oppositely arranged. The first end 1122 is connected to the first corner portion 114. The protrusion 1121 extends from the first corner portion 114 in a direction close to the second end 1123. The protrusion 1121 and the second end 1123 are spaced apart. Along the first direction Y, the maximum dimension of the second wall portion 112 is H, and the maximum dimension of the portion of the protrusion 1121 located on the second wall portion 112 is H1, H1 / H≤0.5, 1mm≤H1≤20mm. Along the thickness direction X of the electrode assembly, the protrusion 1121 is arranged on the outer surface 1124 of the second wall portion, and the maximum dimension of the protrusion 1121 protruding from the outer surface 1124 of the second wall portion is W1. The minimum distance between the pressure relief mechanism 6 and the outer surface 1124 of the second wall portion is W2, which satisfies: 1mm 2 ≤W1×W2≤20mm 2 Along the second direction, the protrusion 1121 has a third end 11212 and a fourth end 11213 opposite to each other, and the pressure relief mechanism is located between the third end 11212 and the fourth end 11213 .

[0303] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0304] The above embodiments are intended only to illustrate the technical solutions of this application and are not intended to limit this application. Those skilled in the art will appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application are intended to be within the scope of protection of this application.

Claims

1. A battery cell, comprising: The electrode assembly is flat; A shell, accommodating the electrode assembly, the shell comprising a first wall portion and a second wall portion that are adjacent and connected, the first wall portion being provided with a pressure relief mechanism, and the second wall portion being arranged opposite to the electrode assembly along a thickness direction of the electrode assembly; Wherein, the second wall portion is provided with a protruding portion, and the protruding portion is used to strengthen the second wall portion.

2. The battery cell according to claim 1, wherein: The first wall portion and the second wall portion are connected via a first corner portion; Along the first direction, the second wall portion has a first end and a second end arranged opposite to each other, the first corner portion is connected to the first end, the protrusion extends from the first corner portion toward the direction close to the second end, and the first direction intersects with the thickness direction of the electrode assembly.

3. The battery cell according to claim 2, wherein: Along the first direction, the protrusion is spaced apart from the second end.

4. The battery cell according to claim 2 or 3, wherein: Along the first direction, the maximum dimension of the second wall portion is H, and the maximum dimension of the portion of the protrusion located on the second wall portion is H1, satisfying: H1 / H≤0.

5.

5. The battery cell according to claim 4, wherein: 0.1mm≤H1≤50mm.

6. The battery cell according to claim 5, wherein: 1mm≤H1≤20mm.

7. The battery cell according to any one of claims 2 to 6, wherein: Along the direction from the first end to the second end, the size of the portion of the protrusion located on the second wall portion in the thickness direction of the electrode assembly gradually decreases.

8. The battery cell according to any one of claims 1 to 7, wherein: Along the thickness direction of the electrode assembly, the protrusion is arranged on the outer surface of the second wall portion, the maximum dimension of the protrusion protruding from the outer surface of the second wall portion is W1, and the minimum distance between the pressure relief mechanism and the outer surface of the second wall portion is W2, which satisfies: 0.3 mm 2 ≤W1×W2≤100mm 2 .

9. The battery cell according to claim 8, wherein: 1mm 2 ≤W1×W2≤20mm 2 。 10. The battery cell according to any one of claims 1 to 9, wherein: The shell further includes a third wall portion, the first wall portion, the second wall portion and the third wall portion are adjacent to and connected in pairs, the first wall portion is located on one side of the second wall portion along the first direction, the third wall portion is located on one side of the second wall portion along the second direction, and the first direction, the second direction and the thickness direction of the electrode assembly intersect in pairs; Wherein, along the second direction, the protrusion has a third end and a fourth end opposite to each other, and the pressure relief mechanism is located between the third end and the fourth end.

11. The battery cell according to claim 10, wherein: Along the second direction, the third wall portions are provided on both sides of the second wall portion, the minimum distance between the third end and the outer surface of one of the third wall portions is A1, the minimum distance between the fourth end and the outer surface of another third wall portion is A2, and the minimum distance between the outer surfaces of the two third wall portions is A, satisfying: |(A1-A2) / A|≤0.

2.

12. The battery cell according to claim 11, wherein: |(A1-A2) / A|≤0.

05.

13. The battery cell according to any one of claims 1 to 12, wherein: Along the thickness direction of the electrode assembly, the second wall portion includes an overlapping area overlapping with the protrusion and a non-overlapping area not overlapping with the protrusion, and the overlapping area and the protrusion together form a thickened area, and the maximum thickness of the thickened area is greater than the maximum thickness of the non-overlapping area.

14. The battery cell according to any one of claims 1 to 13, wherein: The protrusion is arranged on the outer surface of the second wall portion.

15. The battery cell according to any one of claims 1 to 14, wherein: The housing has an opening, and the opening is arranged opposite to the first wall portion.

16. The battery cell according to any one of claims 1 to 15, wherein: The second wall portions are disposed on both sides of the first wall portion along the thickness direction of the electrode assembly.

17. The battery cell according to any one of claims 1 to 16, wherein: The first wall portion is provided with a first groove to form the pressure relief mechanism accordingly, and the first wall portion is configured to be split along the first groove to release the pressure inside the battery cell.

18. The battery cell according to claim 17, wherein: The first slot includes a first slot section, a second slot section and a third slot section. The first slot section is arranged opposite to the third slot section, and the second slot section connects the first slot section and the third slot section.

19. The battery cell according to claim 18, wherein: The residual thickness of the first slot segment and the residual thickness of the third slot segment are both smaller than the residual thickness of the second slot segment.

20. The battery cell according to claim 19, wherein: The residual thickness of the first groove section is D1, and the residual thickness of the second groove section is D2, which satisfies: 0.15≤D1 / D2≤0.

95.

21. The battery cell according to claim 20, wherein: 0.5≤D1 / D2≤0.

85.

22. The battery cell according to claim 20 or 21, wherein: The residual thickness of the third groove segment is D3, which satisfies: 0.15≤D3 / D2≤0.

95.

23. The battery cell according to claim 22, wherein: 0.5≤D3 / D2≤0.

85.

24. The battery cell according to any one of claims 19 to 23, wherein: The first groove also includes at least one fourth groove segment, which is located between the first groove segment and the third groove segment and connected to the second groove segment. The residual thickness of the first groove segment and the residual thickness of the third groove segment are both smaller than the residual thickness of the fourth groove segment.

25. The battery cell according to any one of claims 18 to 24, wherein: Along the extending direction of the second slot segment, two ends of the second slot segment are connected to the first slot segment and the third slot segment respectively.

26. The battery cell according to any one of claims 18 to 25, wherein: The first slot segment, the second slot segment and the third slot segment are all slots extending along a straight line trajectory.

27. The battery cell according to claim 26, wherein: The first wall portion is a rectangular wall portion, the second slot segment extends along the length direction of the first wall portion, and the first slot segment and the third slot segment both extend along the width direction of the first wall portion.

28. The battery cell according to any one of claims 18 to 27, wherein: The first wall portion is provided with a second groove, the second groove and the first groove are arranged along the thickness direction of the first wall portion, the second groove includes a fifth groove segment, a sixth groove segment and a seventh groove segment, the fifth groove segment and the seventh groove segment are arranged opposite to each other, and the sixth groove segment connects the fifth groove segment and the seventh groove segment; The first slot section is arranged on the slot bottom surface of the fifth slot section, the second slot section is arranged on the slot bottom surface of the sixth slot section, and the third slot section is arranged on the slot bottom surface of the seventh slot section.

29. The battery cell according to claim 28, wherein: The first wall portion is provided with a third groove, the third groove, the second groove and the first groove are arranged along the thickness direction of the first wall portion, the third groove includes an eighth groove segment, a ninth groove segment and a tenth groove segment, the eighth groove segment and the tenth groove segment are arranged opposite to each other, and the ninth groove segment connects the eighth groove segment and the tenth groove segment; Among them, the fifth slot segment is arranged on the slot bottom surface of the eighth slot segment, the sixth slot segment is arranged on the slot bottom surface of the ninth slot segment, and the seventh slot segment is arranged on the slot bottom surface of the tenth slot segment.

30. The battery cell according to any one of claims 18 to 29, wherein: The first slot segment has a first midplane extending along its extension direction, the second slot segment has a second midplane extending along its extension direction, the third slot segment has a third midplane extending along its extension direction, the minimum distance from the center point of the outer surface of the first wall portion to the first midplane is M1, the minimum distance from the center point of the outer surface of the first wall portion to the second midplane is M2, and the minimum distance from the center point of the outer surface of the first wall portion to the third midplane is M3, satisfying: M2<M1, M2<M3.

31. The battery cell according to claim 30, wherein: Along the thickness direction of the first wall portion, a projection of a center point of an outer surface of the first wall portion is located within the second groove segment; and / or, |M3-M1|≤5mm.

32. The battery cell according to any one of claims 17 to 31, wherein: The first wall portion is provided with a second groove, and the first groove is provided on a groove bottom surface of the second groove.

33. The battery cell according to claim 32, wherein: The first wall portion is provided with a third groove, and the second groove is provided on a groove bottom surface of the third groove.

34. The battery cell according to any one of claims 1 to 33, wherein: The electrode assembly is a laminated structure, and the stacking direction of the pole pieces in the electrode assembly is parallel to the thickness direction of the electrode assembly.

35. The battery cell according to any one of claims 1 to 33, wherein: The electrode assembly is a winding structure, comprising a straight area and a bending area, wherein the bending area is connected to the straight area, and the stacking direction of the pole pieces in the straight area is parallel to the thickness direction of the electrode assembly.

36. A battery comprising the battery cell according to any one of claims 1 to 35.

37. An electrical device, comprising the battery cell according to any one of claims 1 to 35, wherein the battery cell is used to provide electrical energy to the electrical device.

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