Battery cell, battery, and electric device

Abstract

The present application relates to the technical field of batteries, and relates to a battery cell, a battery, and an electric device. The battery cell comprises an electrode assembly and first limiting members; the electrode assembly comprises a first end surface, a second end surface, and a third end surface; the first end surface and the second end surface are arranged opposite to each other in a first direction, and the third end surface is connected to one end of the same side of the first end surface and the second end surface in a second direction; the first direction is the thickness direction of the electrode assembly, and the second direction is perpendicular to the thickness direction of the electrode assembly; the first limiting members each comprise a first limiting portion, a second limiting portion, and a third limiting portion; the first limiting portion is connected to the first end surface, the second limiting portion is connected to the second end surface, the third limiting portion is connected to the first limiting portion and the second limiting portion, and the third limiting portion and the third end surface are arranged opposite to each other in the second direction; and a first strength weakening area is provided on the third limiting portion, so that the third limiting portion is torn when the expansion coefficient of the electrode assembly in the first direction exceeds a preset value.

Description

Battery cells, batteries, and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application (2024200993738) entitled “Battery Cell, Battery and Electrical Device” filed on January 16, 2024, 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] Energy conservation and emission reduction in vehicle use are key to the sustainable development of the automotive industry. Electric vehicles, due to their energy-saving and environmentally friendly advantages, have become an important component of the sustainable development of the automotive industry. For electric vehicles, battery technology is a crucial factor in their development.

[0005] During the manufacturing process of batteries, battery reliability is an issue that cannot be ignored. Therefore, how to improve battery reliability is a technical problem that needs to be solved urgently in battery technology.

[0006] Summary of the Invention

[0007] The purpose of this application is to provide a battery cell, a battery and an electrical device to address the above problems, so as to improve the above problems and effectively improve the reliability of the battery.

[0008] In the first aspect, the present application provides a battery cell, comprising an electrode assembly and a first limiting member, the electrode assembly comprising a first end face, a second end face and a third end face, the first end face and the second end face being arranged opposite to each other along a first direction, the third end face being connected to the first end face and the second end face at the same side thereof in the second direction, the first direction being the thickness direction of the electrode assembly, and the second direction being perpendicular to the thickness direction of the electrode assembly; the first limiting member comprising a first limiting portion, a second limiting portion and a third limiting portion, the first limiting portion being connected to the first end face, the second limiting portion being connected to the second end face, the third limiting portion connecting the first limiting portion and the second limiting portion, the third limiting portion and the third end face being arranged opposite to each other in the second direction; wherein a first strength weakening zone is provided on the third limiting portion, so that the third limiting portion is torn when the expansion coefficient of the electrode assembly along the first direction exceeds a preset value.

[0009] In the above solution, on the one hand, the first limiting member can realize the connection and fixing function of the electrode assembly to connect the electrode assembly into a whole form, so as to facilitate the picking, transportation, transfer and shelling of the electrode assembly as a whole, thereby improving production efficiency.

[0010] On the other hand, by setting a first strength weakening zone on the third limiting part, the overall tensile strength of the third limiting part is reduced. The third limiting part is opposite to the third end face in the second direction, and the first strength weakening zone is opposite to the side face in the thickness direction of the electrode assembly.

[0011] During normal cycling or when thermal runaway occurs, the electrode assembly will expand in volume, and the expansion mainly occurs in the thickness direction of the electrode assembly, that is, the first direction. Since the third limiting portion is opposite to the third end face, when the electrode assembly expands in the thickness direction, the relative distance between the first end face and the second end face will increase, and the relative positions of the first limiting portion and the second limiting portion will also change accordingly, thereby acting on the third limiting portion and stretching the third limiting portion. It is only necessary to set the specific structure of the first strength weakening zone according to actual needs to match the tensile strength of the third limiting portion to: when the expansion coefficient of the electrode assembly along the first direction exceeds the preset value, the third limiting portion is partially torn or even completely broken by the first strength weakening zone, so that the connection and fixing relationship between the first limiting portion and the second limiting portion becomes invalid, and then the first limiting member fails to restrain the electrode assembly in the first direction, so that the diaphragm and electrode piece of the electrode assembly can adaptively expand in the first direction, thereby protecting the diaphragm and electrode piece, reducing the probability of tearing of the diaphragm and electrode piece and the probability of overall failure of the electrode assembly, thereby improving the reliability and safety performance of the battery.

[0012] According to some embodiments of the present application, the first weakened strength region includes a notch groove, and along the second direction, a projection of the notch groove falls within a projection of the third end surface.

[0013] In the above solution, the first weakened zone is weakened at least by the scored groove. The scored groove reduces the local thickness of the third limiting portion, and the partially hollowed-out structure undermines the overall structural integrity of the third limiting portion, thereby reducing the tensile strength of the third limiting portion. Along the second direction, the projection of the scored groove falls within the projection of the third end face. That is, the projection of the scored groove in the second direction is directly opposite the third end face in the second direction. That is, the position of the scored groove corresponds to the position of the third end face. This allows the scored groove to tear when the electrode assembly expands beyond a preset value in the first direction. This improves the accuracy and stability of the timely tearing or even rupture of the third limiting portion, further enhancing the reliability of the battery cell.

[0014] According to some embodiments of the present application, the length direction of the scoring groove forms an angle with the first direction.

[0015] In the above scheme, the length direction of the notched groove has an angle with the first direction, that is, the length direction of the notched groove is inconsistent with the first direction, so that the notched groove has a component in the direction parallel to the third end face and perpendicular to the first direction, reducing the tensile strength of the third limiting portion when subjected to the tensile force in the first direction, so that in the first direction, the third limiting portion and the first strength weakening area are more likely to break completely when subjected to the tensile force generated by the expansion of the electrode assembly, and after the volume of the electrode assembly expands to a certain proportion along the first direction, the third limiting portion can promptly and quickly reduce or remove the restraining effect on the electrode assembly.

[0016] According to some embodiments of the present application, the notched groove passes through both ends of the third limiting portion along the length direction of the notched groove.

[0017] In the above scheme, the two ends of the length direction of the scored groove are open structures. Since the length direction of the scored groove is inconsistent with the first direction, a long recessed area is formed on the third limiting part by setting a scored groove that passes through the two ends of the third limiting part along the length direction of the scored groove. That is, the physical structure of the third limiting part corresponding to the two ends of the length direction of the scored groove is removed. In other words, the scored groove only includes a groove bottom and two opposite groove walls, which reduces the number of circumferential groove walls of the scored groove. The overall connection of the third limiting part is maintained only by the groove bottom of the scored groove, thereby further weakening the tensile strength of the third limiting part at the scored groove, which can improve the accuracy and stability of the timely tearing or even breaking of the third limiting part, and further improve the reliability of the battery cell.

[0018] According to some embodiments of the present application, there are multiple scoring grooves, and the multiple scoring grooves are arranged at intervals along the third direction, and the third direction has an angle with the second direction.

[0019] In the above solution, the multiple scored grooves refer to two or more scored grooves. The multiple scored grooves, spaced apart along the third direction, work together to reduce the tensile strength of the corresponding portion, such that the tensile strength of the first weakened strength zone is less than the tensile strength of the portion of the third limiting portion located circumferentially near the first weakened strength zone. Furthermore, when the expansion coefficient of the electrode assembly along the first direction exceeds a preset value, the first weakened strength zone can be torn or broken at the location of the scored grooves. The multiple scored grooves ensure that the electrode assembly maintains its strength in the unexpanded state while also allowing for free expansion after expansion to a certain ratio.

[0020] According to some embodiments of the present application, the third direction is the length direction of the notch groove, and the size of the notch groove in the third direction is L, satisfying: 0.01 mm ≤ L ≤ 10 mm.

[0021] In the above solution, a plurality of scoring grooves are spaced apart along the length direction of the scoring groove, and L is the length dimension of the scoring groove.

[0022] On the one hand, there is a solid structure between the cavities of two adjacent notched grooves, which constitutes the groove walls of the two notched grooves, and at the same time connects the first strength weakening zone and the solid structure of the third limiting part located around the first strength weakening zone into one, so as to meet the strength requirements of the connection and fixation of the electrode assembly in the unexpanded state; on the other hand, the total size of all notched grooves in the third direction is increased, thereby increasing the size of the notched grooves parallel to the third end face and perpendicular to the first direction, which is conducive to further reducing the tensile strength of the third limiting part in the first direction, and can be disconnected when the electrode assembly expands to a certain extent and the first strength weakening zone is subjected to tension in the first direction.

[0023] The size L of the notched groove can be adaptively adjusted according to parameters such as the number of required notched grooves and the distance between two adjacent notched grooves in the third direction.

[0024] According to some embodiments of the present application, 0.05 mm ≤ L ≤ 2 mm.

[0025] In the above scheme, according to the safety performance requirements, the volume expansion ratio or thickness expansion ratio (i.e., the preset value of the expansion coefficient) of the electrode assembly in the first direction that is allowed to be constrained by the first limiter can be determined, and then the tensile strength of the first strength weakening zone can be determined. According to the tensile strength, the number of notch grooves, the size L of the notch grooves in the third direction, the distance between two adjacent notch grooves in the third direction, etc. can be selected accordingly.

[0026] By ensuring that the size of the notched groove in the third direction satisfies 0.05mm≤L≤2mm, the strength requirements for connection and fixation of the electrode assembly in the unexpanded state can be better met, while also being more conducive to reducing the tensile strength of the third limiting portion in the first direction.

[0027] According to some embodiments of the present application, the sum of the dimensions of the plurality of notched grooves in the third direction is D1, and the dimension of the third limiting portion in the third direction is D2, satisfying: 0.3≤D1 / D2≤0.9.

[0028] Since multiple notched grooves are arranged at intervals on the third limiting portion, D1 / D2 can obtain a value less than 1, which can characterize the tear resistance of the third limiting portion to a certain extent. Generally speaking, the larger the value, the easier it is for the third limiting portion to be torn by the notched grooves.

[0029] The value obtained by dividing D1 by D2 is controlled between 0.3 and 0.9, which can not only make the third limiting part itself have a certain structural strength, and meet the connection, fixation and restraint requirements when the expansion coefficient of the electrode assembly along the first direction is lower than the preset value, but also be more conducive to reducing the tensile strength of the third limiting part in the first direction to meet the need for releasing the restraint when the expansion coefficient of the electrode assembly along the first direction is higher than the preset value.

[0030] According to some embodiments of the present application, the dimension of the scoring groove in the fourth direction is W, satisfying: 0.01 mm ≤ W ≤ 8 mm, and the fourth direction is the width direction of the scoring groove and has an angle with the third direction.

[0031] In the above scheme, the fourth direction is the width direction of the notched groove, and the fourth direction has an angle with the third direction, that is, the spacing setting direction of multiple notched grooves is inconsistent with the width direction of the notched grooves, which can increase the area occupied by all notched grooves on the third limiting portion to a certain extent, which is beneficial to reducing the tensile strength of the first strength weakening zone.

[0032] W is the width of the notch groove. When the length of the notch groove is determined, the size of the cavity of the notch groove can be determined, and the difficulty of breaking the notch groove can be roughly determined. By setting W between 0.01mm and 8mm, the strength requirement of the connection and fixation of the electrode assembly in the unexpanded state is met, and it can be broken when the electrode assembly expands to a certain extent and the first strength weakening area is subjected to tension in the first direction.

[0033] According to some embodiments of the present application, 0.02 mm ≤ W ≤ 2 mm.

[0034] In the above scheme, according to the safety performance requirements, the volume expansion ratio or thickness expansion ratio (i.e., the preset value of the expansion coefficient) of the electrode assembly in the first direction that is allowed to be constrained by the first limiter can be determined, and then the tensile strength of the first strength weakening zone can be determined. According to the tensile strength, the number of notch grooves, the size W of the notch grooves in the fourth direction, the spacing between two adjacent notch grooves in the third direction, etc. can be selected accordingly.

[0035] By ensuring that the notched groove satisfies 0.02mm≤W≤2mm, the strength requirements for connection and fixation of the electrode assembly in the unexpanded state are further met, while further improving the accuracy and stability of timely tearing or even breaking of the third limiting portion.

[0036] According to some embodiments of the present application, the first strength weakening zone includes a plurality of notch groove groups, each notch groove group includes a plurality of notch grooves spaced apart along a third direction, the third direction has an angle with the second direction, and the plurality of notch groove groups are spaced apart in a fourth direction, which is perpendicular to the third direction.

[0037] In the above scheme, multiple notch groove groups refer to two or more notch groove groups, which work together through multiple notch groove groups spaced apart along the fourth direction to reduce the tensile strength of the third limiting portion, so that the tensile strength of the first strength weakening zone is less than the tensile strength of the part of the third limiting portion located circumferentially near the first strength weakening zone, which can further improve the timeliness and accuracy of tearing or breaking at the position of the notch groove when the first strength weakening zone reaches the failure condition, thereby improving the reliability of the battery cell.

[0038] The arrangement of multiple scoring groove groups and multiple scoring grooves can increase the locations where tearing or breaking may occur. The circumferential groove wall of each scoring groove may be torn or broken due to tensile force, which can meet the strength requirements of the connection and fixation of the electrode assembly in the unexpanded state, while taking into account the requirement that the electrode assembly can be free from constraints and expand freely after expanding to a certain proportion.

[0039] According to some embodiments of the present application, along the first direction, the first limiting portion includes a stacked first adhesive layer and a first substrate layer, and the two sides of the first adhesive layer are respectively connected to the first end face and the first substrate layer; along the first direction, the second limiting portion includes a stacked second adhesive layer and a second substrate layer, and the two sides of the second adhesive layer are respectively connected to the second end face and the second substrate layer.

[0040] In the above scheme, the first limiting portion and the first end face are connected by bonding, and the second limiting portion and the second end face are also connected by bonding. This can protect the surface structure of the first end face and the second end face, and can effectively reduce the damage caused by the first limiting portion and the second limiting portion to the electrode assembly when the electrode assembly undergoes a large volume expansion due to temperature increase, thereby protecting the electrode assembly, reducing the probability of failure of the electrode assembly due to structural damage, and helping to improve performance stability and reliability.

[0041] Furthermore, the primary function of the first and second substrate layers is to provide structural strength to the first and second retaining members, enabling the first retaining member to securely connect the electrode assembly as a single unit, thereby maintaining a fixed relative position within the electrode assembly and facilitating overall transport, transfer, and placement into a battery case. Furthermore, the adhesive bonding between the first retaining member and the first end face, and between the second retaining member and the second end face, further facilitates the manufacture of the battery cell and reduces manufacturing costs.

[0042] According to some embodiments of the present application, along the second direction, the third limiting portion includes a stacked third substrate layer and a third adhesive layer, two sides of the third adhesive layer are respectively connected to the third end surface and the third substrate layer, and at least a portion of the scored groove is provided in the third substrate layer;

[0043] The third base material layer connects the first base material layer and the second base material layer, and the third adhesive layer connects the first adhesive layer and the second adhesive layer.

[0044] In the above scheme, the third limiting part and the third end face also use a bonding connection scheme, and the first limiting part, the second limiting part and the third limiting part are all bonded to the corresponding first end face, the second end face and the third end face, so that the first limiting part, the second limiting part and the third limiting part can all respond to the relative position change of the first end face and the second end face in the first direction when the electrode assembly expands, so that when the third limiting part is stretched, in addition to being subjected to the tensile force of the first limiting part and the second limiting part, it is also subjected to the resistance of the third end face, which increases the force form of the first strength weakening zone, and thereby enables the first strength weakening zone to better respond to the change in the expansion coefficient of the electrode assembly along the first direction, so that it can be torn or broken in time.

[0045] The third substrate layer serves as the primary strength component of the third retaining portion, and together with the first and second substrate layers, secures the electrode assembly together. This stabilizes the relative positions of the electrode assembly's internal structures, facilitating overall handling, transfer, and packaging. The scored grooves are at least partially disposed in the third substrate layer. Specifically, the scored grooves are primarily intended to reduce the tensile strength of the third substrate layer in the first weakened zone, enabling the third substrate layer to tear under predetermined conditions.

[0046] According to some embodiments of the present application, the thickness of the third substrate layer is h, which satisfies: 5 μm≤h≤50 μm.

[0047] In the above scheme, the overall strength of the third limiter is primarily determined by the third substrate layer, and the specific structural design of the first strength reduction zone is also related to the structural strength of the third substrate layer. Whether the first strength reduction zone can be broken in a timely manner is also primarily determined by the substrate layer. By setting the thickness of the third substrate layer between 5μm and 50μm, on the one hand, the size of the first limiter in the second direction can at least be controlled within a smaller range, thereby effectively controlling the total size of the first limiter and the electrode assembly in the second direction, which is beneficial for controlling the total size of the battery cell in the second direction and improving the battery's spatial energy density. On the other hand, the thickness of the third substrate layer is relatively small. After the notch groove is set on the third substrate layer, the thickness at the first strength reduction zone is reduced, which effectively reduces the tensile strength of the first strength reduction zone and enables the third substrate layer to tear under preset conditions.

[0048] According to some embodiments of the present application, the electrode assembly further includes a fourth end surface connected to the other end of the first end surface and the second end surface on the same side in the second direction;

[0049] The battery cell further includes a second limiting member, the second limiting member including a fourth limiting portion, a fifth limiting portion, and a sixth limiting portion, the fourth limiting portion being connected to the first end surface, the fifth limiting portion being connected to the second end surface, the sixth limiting portion connecting the fourth limiting portion and the fifth limiting portion, and the sixth limiting portion being arranged opposite to the fourth end surface in the second direction;

[0050] The sixth limiting portion is provided with a second strength weakening area so that the third limiting portion is torn when the expansion coefficient of the electrode assembly along the first direction exceeds a preset value.

[0051] In the above scheme, in the second direction, the third end face and the fourth end face are located at the opposite ends of the first end face and the second end face, and the second limiter and the first limiter are also located at the opposite ends of the first end face and the second end face, that is, the electrode assembly is connected and fixed by the first limiter at the end where the third end face is located, and the electrode assembly is connected and fixed by the second limiter at the end where the fourth end face is located. The first limiter and the second limiter act together on the electrode assembly to connect and fix the electrode assembly as a whole, limit the relative position between the internal structures of the electrode assembly, and improve the connection and fixing effect.

[0052] The working principle is the same as that of the first limiter. By setting a second strength weakening zone on the sixth limiter, the overall tensile strength of the sixth limiter is reduced. The sixth limiter is opposite to the fourth end face in the second direction, and the second strength weakening zone is also located in the thickness direction of the electrode assembly. When the electrode assembly is heated or expands due to thermal runaway, the relative positions of the first end face and the second end face in the first direction are related. When the expansion coefficient of the electrode assembly in the first direction exceeds a preset value, the relative distance between the first end face and the second end face increases and stretches the sixth limiter, so that the sixth limiter is partially torn or broken by the second strength weakening zone, and the force of the second limiter on the first end face and the second end face is reduced or dropped to zero, and then the restraining effect of the second limiter on the electrode assembly in the first direction fails, so that the diaphragm and the pole piece of the electrode assembly can adaptively expand in the first direction, thereby protecting the diaphragm and the pole piece, reducing the probability of tearing of the diaphragm and the pole piece and the probability of overall failure of the electrode assembly, thereby improving the reliability and safety performance of the battery.

[0053] According to some embodiments of the present application, the first limiting portion is connected to the fourth limiting portion, the second limiting portion is connected to the fifth limiting portion, and the first limiting member and the second limiting member are an integrally formed member.

[0054] In the above scheme, the first limiter and the second limiter are integrally wound around the electrode assembly, and the first strength weakening zone and the second strength weakening zone are respectively provided on the third limiter and the sixth limiter located in the thickness direction, so that the first strength weakening zone and the second strength weakening zone are stretched as the electrode assembly expands in the first direction. The third limiter and the sixth limiter can be torn when the expansion coefficient of the electrode assembly along the first direction exceeds a preset value, so that the electrode assembly is no longer constrained in the first direction, that is, the thickness direction, and can expand freely, which can effectively protect the structure of the electrode assembly and improve the reliability and safety performance of the battery cell.

[0055] According to some embodiments of the present application, the second direction is the length direction or the width direction of the electrode assembly.

[0056] In the above scheme, the second direction is the length direction or width direction of the electrode assembly, and the third end face is located at one end of the length direction of the electrode assembly, or at one end of the width direction of the electrode assembly. That is to say, the third limiting portion is arranged on one side of the length direction or one side of the width direction of the electrode assembly. The first limiting member can more stably connect and fix the electrode assembly, and can also more accurately sense the dimensional changes of the electrode assembly in the first direction, that is, the thickness direction, which is conducive to improving the accuracy and reliability of timely tearing and breaking of the third limiting portion.

[0057] According to some embodiments of the present application, the electrode assembly is a wound electrode assembly or a laminated electrode assembly.

[0058] In the above scheme, when the electrode assembly is a wound electrode assembly, the electrode assembly is wound to form a multi-layer structure, and the first direction is the stacking direction of the multi-layer structure, that is, the direction outward from the winding center axis. When the electrode assembly is a laminated electrode assembly, the first direction is the stacking direction of the alternating electrode sheets and separators. The principle of the lamination process determines that the electrode sheets and separators of the battery cell will not bend during the manufacturing process, and can be fully unfolded and stacked together, which not only reduces the internal resistance of the battery cell and increases the battery cell power, but also improves the battery energy density.

[0059] Regardless of whether it is a wound electrode assembly or a laminated electrode assembly, the overall shape and structure of the electrode assembly are relatively regular, which facilitates the setting of a first limiting member to smoothly connect the first limiting portion and the first end face, and connect the second limiting portion and the second end face.

[0060] According to some embodiments of the present application, the battery cell further includes a shell, the shell is provided with a receiving cavity, and the electrode assembly and the first limiting member are both provided in the receiving cavity.

[0061] In the above solution, the outer shell provides a cavity for the electrode assembly connected to the first retainer. The cavity also accommodates electrolyte and other components, making it easy to insert the entire electrode assembly into the shell after being connected and fixed by the first retainer. In addition, the outer shell has a certain hardness and strength, which makes it less likely to deform when squeezed or collided, thus providing the battery cell with higher structural strength and improved safety performance.

[0062] In a second aspect, a battery is provided, which includes the battery cell in the above embodiment.

[0063] In a third aspect, an electrical device is provided, which includes the battery cell in the above embodiment and / or the battery in the above embodiment, and the battery cell and / or the battery are used to provide electrical energy.

[0064] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] 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.

[0066] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application.

[0067] FIG2 is a schematic diagram of the structure of a battery provided in some embodiments of the present application.

[0068] FIG3 is a schematic diagram of the overall structure of an electrode assembly and a first limiting member of a battery cell provided in some embodiments of the present application.

[0069] FIG4 is a front view of the overall structure of the electrode assembly and the first limiting member in FIG3 .

[0070] FIG5 is a right side view of the overall structure of the electrode assembly and the first limiting member in FIG3 .

[0071] FIG6 is a rear view of the overall structure of the electrode assembly and the first limiting member of FIG3 .

[0072] FIG7 is a schematic diagram of the overall structure after the first limiting member in FIG3 is connected to the electrode assembly.

[0073] FIG8 is a schematic diagram of a product roll of a first limiting member provided in some embodiments of the present application.

[0074] FIG9 is a partial schematic diagram of FIG8 .

[0075] FIG10 is an axonometric schematic diagram of FIG9 .

[0076] In the drawings, the drawings are not drawn to scale.

[0077] Icons: 1000-Vehicle; 100-Battery; 200-Motor; 300-Controller; 10-Casing; 11-First Part; 12-Second Part; 20-Battery Cell; 21-Electrode Assembly; 211-First End Surface; 212-Second End Surface; 213-Third End Surface; 214-Fourth End Surface; 215-First End Surface; 216-Second End Surface; 22-First Stopper; 221-First Stopper; 2211-First Base Material Layer; 2212- First adhesive layer; 222-second limiting portion; 2221-second base material layer; 2222-second adhesive layer; 223-third limiting portion; 2231-third base material layer; 2232-third adhesive layer; 224-first strength reduction zone; 23-second limiting member; 231-fourth limiting portion; 232-fifth limiting portion; 233-sixth limiting portion; 234-second strength reduction zone; 24-third limiting member; 241-third strength reduction zone; 25-notch groove. DETAILED DESCRIPTION

[0078] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0079] 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 only for the purpose of describing specific embodiments 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.

[0080] 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. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0081] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0082] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0083] The term "multiple" in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0084] In this application, the battery 100 mentioned herein refers to a single physical module including one or more battery cells 20 to provide higher voltage and capacity. For example, the battery 100 mentioned herein may include a battery module or a battery pack.

[0085] Currently, market developments indicate that power batteries 100 are increasingly being used. Power batteries 100 are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace applications. As the application areas of power batteries 100 continue to expand, market demand is also growing.

[0086] For battery cells, the electrode assembly, i.e., the bare cell, is usually first connected and fixed by other structures such as adhesive tape or connectors to facilitate overall transportation and shell placement. After the battery cell is put into use, during normal circulation or when thermal runaway occurs, the electrode assembly will expand in volume. However, for battery cells in the related art, no matter how much the electrode assembly expands, even when the volume expansion ratio is large due to thermal runaway, the adhesive tape or connectors are still always connected and fixed to the electrode assembly, and always restrain the electrode assembly in the expansion direction of the electrode assembly. Due to the restraining effect of the connector and the inconsistency of the expansion coefficients of the electrode sheet and the connector of the electrode assembly, the expansion coefficient of the connector is smaller, so that the expansion ratio of the part restricted by the connector will be smaller than the expansion ratio of the part not restricted by the connector, which will cause the diaphragm or electrode sheet of the electrode assembly to tear, or even cause the entire electrode assembly to fail. Therefore, there is a problem of low reliability in the related art.

[0087] Based on the above considerations, in order to improve the reliability of the battery and effectively protect the structure of the electrode assembly, a battery cell 20 is designed, including an electrode assembly 21 and a first limiter 22. The electrode assembly 21 includes a first end face 211, a second end face 212 and a third end face 213. Along a first direction, the first end face 211 and the second end face 212 are arranged opposite to each other, and the third end face 213 is connected to the first end face 211 and the second end face 212 on the same side in the second direction. The first direction is the thickness direction of the electrode assembly 21, and the second direction is perpendicular to the thickness direction of the electrode assembly 21; A limiting member 22 includes a first limiting portion 221, a second limiting portion 222 and a third limiting portion 223, the first limiting portion 221 is connected to the first end face 211, the second limiting portion 222 is connected to the second end face 212, the third limiting portion 223 connects the first limiting portion 221 and the second limiting portion 222, and the third limiting portion 223 and the third end face 213 are arranged relative to each other in the second direction; wherein, a first strength weakening zone 224 is provided on the third limiting portion 223, so that the third limiting portion 223 is torn when the expansion coefficient of the electrode assembly 21 along the first direction exceeds a preset value.

[0088] Compared to battery cells in related art, the battery cell 20 provided in this application features an electrode assembly 21 connected and fixed as a single unit by a first retaining member 22, allowing for integrated handling, transfer, and placement into a shell. A third retaining portion 223, opposing the third end face 213, is located in the first direction, i.e., the thickness direction of the electrode assembly 21. By providing a first weakened zone 224 on the third retaining portion 223, also located in the first direction, the overall tensile strength of the third retaining portion 223 in the first direction is reduced. When the electrode assembly 21 expands, the expansion and dimensional change mainly occur in the thickness direction, and the relative distance between the first end face 211 and the second end face 212 in the first direction increases, and then the relative distance between the first limiting portion 221 and the second limiting portion 222 in the first direction also increases, and acts on the two ends of the third limiting portion 223 in the first direction and stretches the third limiting portion 223, matching the tensile strength of the third limiting portion 223 to: when the expansion coefficient of the electrode assembly 21 along the first direction exceeds the preset value, the third limiting portion 223 is partially torn or even completely broken by the first strength weakening zone 224, so that the connection and fixing relationship between the first limiting portion 221 and the second limiting portion 222 fails, and then the restraining effect of the first limiting member 22 on the electrode assembly 21 in the first direction fails, so that the diaphragm and the electrode piece of the electrode assembly 21 can adaptively expand in the first direction, thereby protecting the diaphragm and the electrode piece, reducing the probability of tearing of the diaphragm and the electrode piece and the probability of overall failure of the electrode assembly 21, thereby improving the reliability and safety performance of the battery 100.

[0089] The battery cells 20 disclosed in the embodiments of this application can be used, but are not limited to, in electrical devices such as vehicles 1000, ships, or aircraft. A power supply system comprising the battery cells 20 disclosed in this application and a battery 100 can be used to form such an electrical device. This can improve the safety of the battery cells 20 and facilitate the promotion of the battery 100.

[0090] The present invention provides an electric device using a battery 100 as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0091] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0092] Please refer to Figure 1, which is a structural diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 300 and a motor 200. The controller 300 is used to control the battery 100 to power the motor 200, for example, for starting, navigating and driving the vehicle 1000.

[0093] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0094] Please refer to Figure 2, which is an exploded view of a battery 100 provided in some embodiments of the present application. The battery includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 provides a storage space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for the battery cell 20. The second portion 12 can be a hollow structure with one end open. The first portion 11 can be a plate-like structure, with the first portion 11 overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 together define a storage space. Alternatively, the first portion 11 and the second portion 12 can each be a hollow structure with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0095] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0096] Each battery cell 20 may be a secondary battery or a primary battery, and may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0097] The battery cell 20 may contain one or more electrode assemblies 21. The electrode assembly 21 is a component in the battery cell 20 where electrochemical reactions occur. The adapter is a component in the battery cell 20 that transmits current. The electrode assembly 21 is mainly formed by winding or stacking the positive electrode sheet and the negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. The parts of the positive electrode sheet and the negative electrode sheet with active materials constitute the main body of the electrode assembly 21, and the parts of the positive electrode sheet and the negative electrode sheet without active materials are each provided with a tab. The positive electrode tab and the negative electrode tab can be located together at one end of the main body or respectively at both ends of the main body. During the charging and discharging process of the battery 100, the positive electrode active material and the negative electrode active material react with the electrolyte, and the adapter is connected between the tab and the electrode terminal to form a current loop.

[0098] In some embodiments, the battery cells 20 may be provided with functional components such as electrode terminals. The electrode terminals may be used to electrically connect the electrode assembly 21 and the busbar member to output or input electrical energy to or from the battery cells 20. In some embodiments, the battery cells 20 may also be provided with a pressure relief mechanism for relieving internal pressure when the internal pressure or temperature of the battery cells 20 reaches a threshold.

[0099] According to some embodiments of the present application, as shown in Figures 3 to 10, a battery cell 20 is provided, comprising an electrode assembly 21. The electrode assembly 21 includes a first end face 211, a second end face 212, and a third end face 213. The first end face 211 and the second end face 212 are disposed opposite each other along a first direction, and the third end face 213 is connected to ends of the first end face 211 and the second end face 212 on the same side in a second direction. The first direction is the thickness direction of the electrode assembly 21, and the second direction is perpendicular to the thickness direction of the electrode assembly 21. The electrode assembly 21 is the component in the battery cell 20 where the electrochemical reaction occurs. The electrode assembly 21 is primarily formed by winding or stacking positive and negative electrode sheets, and a separator is typically provided between the positive and negative electrode sheets. The portions of the positive and negative electrode sheets containing active material constitute the main body of the electrode assembly 21, while the portions of the positive and negative electrode sheets not containing active material are each provided with a tab. The positive and negative electrode tabs can be located together at one end of the main body or separately at opposite ends. During the charging and discharging processes of the battery 100, the positive and negative electrode active materials react with the electrolyte, and the adapter is connected between the tabs and the electrode terminals to form a current circuit.

[0100] As shown in Figure 3, the first direction is the thickness direction of the electrode assembly 21, corresponding to the Z direction in the figure, and the first end surface 211 and the second end surface 212 are opposite each other in the thickness direction. When the electrode assembly 21 is a wound electrode assembly 21, the electrode assembly 21 is wound to form a multi-layer structure. The first direction is the stacking direction of the multi-layer structure, that is, the direction from the winding center axis outward. When the electrode assembly 21 is a laminated electrode assembly 21, the first direction is the stacking direction of the alternating positive and negative electrode sheets.

[0101] As shown in FIG3 , the second direction is the X-direction 21, and the electrode assembly 21 has a first end 215 and a second end 216 opposite each other in the second direction. The third end surface 213 is connected to the first end surface 211 and the second end surface 212 on the same side of the second direction. The same side herein means that the end of the first end surface 211 corresponding to the first end 215 and the end of the second end surface 212 corresponding to the first end 215 are located on the same side. In other words, one end of the third end surface 213 in the first direction is connected to the end of the first end surface 211 corresponding to the first end 215, and the other end of the third end surface 213 in the first direction is connected to the end of the second end surface 212 corresponding to the first end 215.

[0102] The battery cell 20 also includes a first limiting member 22, which includes a first limiting portion 221, a second limiting portion 222 and a third limiting portion 223. The first limiting portion 221 is connected to the first end face 211, the second limiting portion 222 is connected to the second end face 212, and the third limiting portion 223 connects the first limiting portion 221 and the second limiting portion 222. The third limiting portion 223 and the third end face 213 are arranged relative to each other in the second direction; wherein, a first strength weakening zone 224 is provided on the third limiting portion 223, so that the third limiting portion 223 is torn when the expansion coefficient of the electrode assembly 21 along the first direction exceeds a preset value.

[0103] The first limiting member 22 is used to fix the ends of the positive and negative electrode sheets after winding so that the electrode assembly 21 will not unwind, or to limit the relative positions of the stacked positive and negative electrode sheets so that the multi-layer positive and negative electrode sheets form an integral structure. The first limiting member 22 can realize the connection and fixing function of the electrode assembly 21 to connect the electrode assembly 21 into an integral form, so as to facilitate the picking, handling, transfer and shelling of the electrode assembly 21 as a whole, thereby improving production efficiency.

[0104] The number of the first limiting member 22 can be one or more.

[0105] The first limiting portion 221 is connected to the first end surface 211 , the second limiting portion 222 is connected to the second end surface 212 , and the third limiting portion 223 is connected to the first limiting portion 221 and the second limiting portion 222 , thereby limiting the relative movement of the first end surface 211 and the second end surface 212 in the first direction.

[0106] First weakened zone 224 is used to reduce the local structural strength and tensile strength of third limiting portion 223. Since third limiting portion 223 and third end surface 213 are opposed in the second direction, first weakened zone 224 is opposed to the side surface of electrode assembly 21 in the thickness direction. Tensile strength, also known as tensile strength or tear strength, refers to the ratio of the maximum load a specimen can withstand when stretched to break to the cross-sectional area of ​​the specimen. It represents the crushing force per unit area, symbolized by σt. It characterizes the ability of a material or component to resist damage when subjected to tension and can be expressed as ultimate strength. It is an indicator of the mechanical properties of metallic and non-metallic materials.

[0107] During normal circulation or when thermal runaway occurs, the volume of the electrode assembly 21 will expand, and the expansion mainly occurs in the thickness direction of the electrode assembly 21, that is, the first direction. Since the third limiting portion 223 is opposite to the third end face 213, when the electrode assembly 21 expands in the thickness direction, the relative distance between the first end face 211 and the second end face 212 will increase, and the relative positions of the first limiting portion 221 and the second limiting portion 222 will also change accordingly, thereby acting on the two ends of the third limiting portion 223 in the first direction and stretching the third limiting portion 223. It is only necessary to set the specific structure of the first strength reduction zone 224 according to actual needs to reduce the third The tensile strength matching of the limiting portion 223 is as follows: when the expansion coefficient of the electrode assembly 21 along the first direction (i.e., the Z direction) exceeds the preset value, the third limiting portion 223 is partially torn or even completely broken by the first strength weakening zone 224, so that the connection and fixing relationship between the first limiting portion 221 and the second limiting portion 222 is invalidated, and then the restraining effect of the first limiting member 22 on the electrode assembly 21 in the first direction is invalidated, so that the diaphragm and the electrode piece of the electrode assembly 21 can adaptively expand in the first direction, thereby protecting the diaphragm and the electrode piece, reducing the probability of tearing the diaphragm and the electrode piece and the probability of overall failure of the electrode assembly 21, thereby improving the reliability and safety performance of the battery 100.

[0108] It should be noted that, in some embodiments, the first weakened strength region 224 can be made of a material with a lower strength than the other portions of the third limiting portion 223. That is, the portion of the third limiting portion 223 corresponding to the first weakened strength region 224 and the portion other than the first weakened strength region 224 can be made of materials with different strengths. In other embodiments, the first weakened strength region 224 can also be formed by adding strength-reducing structures to the third limiting portion 223. Furthermore, the third limiting portion 223 and the third end surface 213 can be connected or disconnected.

[0109] According to some embodiments of the present application, the first weakened strength region 224 includes a notch groove 25 , and along the second direction, a projection of the notch groove 25 falls within a projection of the third end surface 213 .

[0110] The scored groove 25 is a structure that weakens the local strength of the third limiting portion 223, thereby forming an area of ​​even lower strength on the third limiting portion 223, namely, the first weakened strength zone 224. In other words, the weakening of the first weakened strength zone 224 is achieved at least by the scored groove 25. The scored groove 25 reduces the local thickness of the third limiting portion 223 and, through the partially hollowed-out structure, destroys the overall structural integrity of the third limiting portion 223, thereby reducing the tensile strength of the third limiting portion 223.

[0111] Along the second direction, the projection of the notched groove 25 falls within the projection of the third end face 213 , that is, the projection of the notched groove 25 in the second direction is directly opposite to the third end face 213 in the second direction, that is, the setting position of the notched groove 25 corresponds to the position of the third end face 213 .

[0112] In the above solution, on the one hand, at least the structure of the scored groove 25 undermines the overall structural integrity of the third limiting portion 223, achieving the effect of making the strength of the first weakened strength region 224 weaker than the strength of the rest of the third limiting portion 223, thereby reducing the tensile strength of the third limiting portion 223. On the other hand, by ensuring that the projection of the scored groove 25 along the second direction falls completely within the projection of the third end surface 213, the scored groove 25 can be torn when the expansion of the electrode assembly 21 in the first direction exceeds a preset value. This improves the accuracy and stability of the timely tearing or even rupture of the third limiting portion 223, further enhancing the reliability of the battery cell 20.

[0113] According to some embodiments of the present application, the length direction of the scoring groove 25 forms an angle with the first direction.

[0114] As shown in Figures 3 and 5, in this embodiment, the length direction of the scored groove 25 is perpendicular to the first direction and is the length direction of the electrode assembly 21. Of course, in other embodiments, the length direction of the scored groove 25 can be arranged at an angle to both the first direction and the length direction of the electrode assembly 21, and this application is not limited thereto. For example, in some embodiments, the length direction of the scored groove 25 can be perpendicular to the first direction.

[0115] In the above scheme, the length direction of the notched groove 25 has an angle with the first direction, that is, the length direction of the notched groove 25 is inconsistent with the first direction, so that the notched groove 25 can have a component in the direction parallel to the third end face 213 and perpendicular to the first direction, reducing the tensile strength of the third limiting portion 223 when subjected to the tensile force in the first direction, so that in the first direction, the third limiting portion 223 and the first strength weakening zone 224 are more likely to break completely when subjected to the tensile force generated by the expansion of the electrode assembly 21, and after the volume of the electrode assembly 21 expands to a certain proportion along the first direction, the third limiting portion 223 can promptly and quickly reduce or remove the restraining effect on the electrode assembly 21.

[0116] According to some embodiments of the present application, along the length direction of the scoring groove 25 , the scoring groove 25 passes through both ends of the third limiting portion 223 .

[0117] The two ends of the notched groove 25 in the longitudinal direction are open structures. Since the longitudinal direction of the notched groove 25 is inconsistent with the first direction, a notched groove 25 is provided that passes through the two ends of the third limiting portion 223 along the longitudinal direction of the notched groove 25. A long recessed area is formed on the third limiting portion 223, and the two ends of the notched groove 25 in the longitudinal direction are open structures, that is, the two ends of the recessed area corresponding to the longitudinal direction of the notched groove 25 are also open structures, that is, the physical structure of the third limiting portion 223 corresponding to the two ends of the longitudinal direction of the notched groove 25 is removed.

[0118] In the above scheme, the notched groove 25 only includes a groove bottom and two opposite groove walls, which reduces the number of circumferential groove walls of the notched groove 25, and only relies on the groove bottom of the notched groove 25 to maintain the overall connection of the third limiting part 223, thereby further weakening the tensile strength of the third limiting part 223 at the notched groove 25, and can improve the accuracy and stability of the third limiting part 223 in timely tearing or even breaking, thereby further improving the reliability of the battery cell 20.

[0119] According to some embodiments of the present application, there are multiple scoring grooves 25, and the multiple scoring grooves 25 are arranged at intervals along the third direction, and the third direction has an angle with the second direction.

[0120] As shown in Figure 3, the second direction is the width direction of the electrode assembly 21, i.e., the X direction, and the third direction is the length direction of the notch groove 25, i.e., the length direction of the electrode assembly 21, i.e., the Y direction. In this embodiment, the first direction, the second direction, and the third direction are perpendicular to each other.

[0121] A plurality of scoring grooves 25 refers to two or more scoring grooves 25 .

[0122] In the above solution, multiple scored grooves 25 spaced apart along the third direction work together to reduce the tensile strength of the corresponding portion, ensuring that the tensile strength of the first weakened strength region 224 is less than the tensile strength of the portion of the third limiting portion 223 located circumferentially near the first weakened strength region 224. This also ensures that when the expansion coefficient of the electrode assembly 21 along the first direction exceeds a preset value, the first weakened strength region 224 can be torn or broken at the location of the scored grooves 25. The arrangement of multiple scored grooves 25 meets the strength requirements for securing the connection of the electrode assembly 21 in its unexpanded state, while also allowing for free expansion after the electrode assembly 21 has expanded to a certain ratio.

[0123] According to some embodiments of the present application, the third direction is the length direction of the scoring groove 25 , and the dimension of the scoring groove 25 in the third direction is L, which satisfies: 0.01 mm ≤ L ≤ 10 mm.

[0124] L can be selected from 0.01mm, 0.03mm, 0.05mm, 1mm, 2mm, 3mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 7mm, 7.8mm, 8mm, 8.3mm, 9mm, 9.5mm, 10mm, etc.

[0125] In the above solution, the plurality of scoring grooves 25 are spaced apart along the length direction of the scoring groove 25 , and L is the length dimension of the scoring groove 25 .

[0126] On the one hand, there is a solid structure between the cavities of two adjacent notched grooves 25, which constitutes the groove walls of the two notched grooves 25, and at the same time connects the first strength weakening zone 224 and the solid structure of the third limiting portion 223 located around the first strength weakening zone 224 into one, so as to meet the strength requirements of the connection and fixation of the electrode assembly 21 in the unexpanded state; on the other hand, the total size of all notched grooves 25 in the third direction is increased, thereby increasing the size of the notched groove 25 parallel to the third end face 213 and perpendicular to the first direction, which is conducive to further reducing the tensile strength of the third limiting portion 223 in the first direction, and can be disconnected when the electrode assembly 21 expands to a certain extent and the first strength weakening zone 224 is subjected to tension in the first direction.

[0127] The size L of the notched groove 25 can be adaptively adjusted according to parameters such as the number of notched grooves 25 required and the distance between two adjacent notched grooves 25 in the third direction.

[0128] According to some embodiments of the present application, 0.05 mm ≤ L ≤ 2 mm.

[0129] L can be selected from 0.05mm, 0.08mm, 0.12mm, 0.15mm, 0.2mm, 0.3mm, 0.35mm, 0.40mm, 0.45mm, 0.5mm, 0.7mm, 0.9mm, 1mm, 1.3mm, 1.5mm, 1.8mm, 2mm, etc.

[0130] In the above scheme, according to the safety performance requirements, the volume expansion ratio or thickness expansion ratio (i.e., the preset value of the expansion coefficient) of the electrode assembly 21 in the first direction that is allowed to be constrained by the first limiter 22 can be determined, and then the tensile strength of the first strength weakening zone 224 can be determined. According to the tensile strength, the number of notched grooves 25, the size L of the notched grooves 25 in the third direction, the distance between two adjacent notched grooves 25 in the third direction, etc. can be selected accordingly.

[0131] By ensuring that the size of the notched groove 25 in the third direction satisfies 0.05mm≤L≤2mm, the strength requirement for connection and fixation of the electrode assembly 21 in the unexpanded state can be better met, while being more conducive to reducing the tensile strength of the third limiting portion 223 in the first direction.

[0132] For example, when the tensile strength of the first weakened strength zone 224 is determined, the number of notched grooves 25 can be increased to better meet the connection and fixation requirements when the expansion coefficient of the electrode assembly 21 along the first direction is lower than a preset value.

[0133] According to some embodiments of the present application, as shown in FIG5 and FIG9 , the sum of the dimensions of the plurality of notched grooves 25 in the third direction is D1, and the dimension of the third limiting portion 223 in the third direction is D2, satisfying: 0.3≤D1 / D2≤0.9.

[0134] Because the multiple scored grooves 25 are spaced apart on the third limiting portion 223, the ratio D1 / D2 can be less than 1. This ratio can, to a certain extent, indicate the tear resistance of the third limiting portion 223. Generally, the larger the ratio, the easier it is for the third limiting portion 223 to tear at the cavity of the scored grooves 25. Once the tensile strength of the first weakened zone 224 is determined, the relationship and ratio between D1 and D2 can be used to further determine parameters such as the number of scored grooves 25, the dimension L of a single scored groove 25 in the third direction, and the spacing between two adjacent scored grooves 25 in the third direction.

[0135] The value obtained by dividing D1 by D2 is controlled between 0.3 and 0.9, which can not only ensure that the third limiting portion 223 itself has a certain structural strength and can meet the connection, fixation and restraint requirements when the expansion coefficient of the electrode assembly 21 along the first direction is lower than the preset value, but also can be more conducive to reducing the tensile strength of the third limiting portion 223 in the first direction to meet the need for releasing the restraint when the expansion coefficient of the electrode assembly 21 along the first direction is higher than the preset value.

[0136] For example, the ratio between D1 and D2 can be 0.3, 0.4, 0.45, 0.5, 0.6, 0.66, 0.7, 0.8, 0.85, 0.9, etc.

[0137] According to some embodiments of the present application, the dimension of the scoring groove 25 in the fourth direction is W, satisfying: 0.01 mm ≤ W ≤ 8 mm, and the fourth direction is the width direction of the scoring groove 25 and has an angle with the third direction.

[0138] W can be selected from 0.01mm, 0.05mm, 1mm, 2mm, 2.5mm, 3.5mm, 4mm, 4.5mm, 5.3mm, 5.8mm, 6mm, 7mm, 7.5mm, 8mm, etc.

[0139] As shown in FIG. 3 and FIG. 5 , in this embodiment, the fourth direction is the width direction of the notch groove 25 , that is, the thickness direction of the electrode assembly 21 , that is, the first direction is consistent with the fourth direction.

[0140] In the above scheme, the fourth direction has an angle with the third direction, that is, the spacing setting direction of the multiple notched grooves 25 is inconsistent with the width direction of the notched grooves 25, which can increase the area occupied by all notched grooves 25 on the third limiting portion 223 to a certain extent, which is beneficial to reducing the tensile strength of the first strength weakening zone 224.

[0141] W is the width dimension of the notched groove 25. When the length of the notched groove 25 is determined, the size of the cavity of the notched groove 25 can be determined, and then the difficulty of breaking the notched groove 25 can be roughly determined. By setting W between 0.01mm and 8mm, the strength requirement of the connection and fixation of the electrode assembly 21 in the unexpanded state is met, and the electrode assembly 21 can be broken when it expands to a certain extent and the first strength weakening zone 224 is subjected to tension in the first direction.

[0142] According to some embodiments of the present application, 0.02 mm ≤ W ≤ 2 mm.

[0143] W can be selected from 0.02mm, 0.05mm, 0.08mm, 0.12mm, 0.15mm, 0.2mm, 0.3mm, 0.35mm, 0.40mm, 0.45mm, 0.5mm, 0.7mm, 0.9mm, 1mm, 1.3mm, 1.5mm, 1.8mm, 2mm, etc.

[0144] In the above scheme, according to the safety performance requirements, the volume expansion ratio or thickness expansion ratio (i.e., the preset value of the expansion coefficient) of the electrode assembly 21 in the first direction that is allowed to be constrained by the first limiter 22 can be determined, and then the tensile strength of the first strength weakening zone 224 can be determined. According to the tensile strength, the number of notched grooves 25, the size W of the notched grooves 25 in the fourth direction, the spacing between two adjacent notched grooves 25 in the third direction, etc. can be selected accordingly.

[0145] By ensuring that the notched groove 25 satisfies 0.02 mm ≤ W ≤ 2 mm, the strength requirement for connection and fixation of the electrode assembly 21 in the unexpanded state is further met, while the accuracy and stability of timely tearing or even breaking of the third limiting portion 223 can be further improved.

[0146] In some embodiments, when the tensile strength of the first strength weakening zone 224 is determined, the total volume of the physical structure of the first strength weakening zone 224 can be increased by increasing the number of notched grooves 25, thereby ensuring the structural strength of the first strength weakening zone 224 and better meeting the connection and fixation requirements when the expansion coefficient of the electrode assembly 21 along the first direction is lower than a preset value.

[0147] According to some embodiments of the present application, the first strength weakening zone 224 includes a plurality of notch groove groups, each notch groove group includes a plurality of notch grooves 25 spaced apart along a third direction, the third direction has an angle with the second direction, and the plurality of notch groove groups are spaced apart in a fourth direction, which is perpendicular to the third direction.

[0148] A plurality of scored groove groups refers to two or more scored groove groups, and a plurality of scored grooves 25 refers to two or more scored grooves 25. The second direction is the width direction of the electrode assembly 21, and the third direction is the length direction of the scored groove 25 (i.e., the length direction of the electrode assembly 21). Therefore, the fourth direction can be consistent with the first direction, can also be consistent with the second direction, and can also have a projection component parallel to both the first direction and the second direction.

[0149] In the above scheme, multiple notch groove groups refer to two or more notch groove groups, which work together through multiple notch groove groups spaced apart along the fourth direction to reduce the tensile strength of the third limiting portion 223, so that the tensile strength of the first strength weakening zone 224 is less than the tensile strength of the portion of the third limiting portion 223 located circumferentially near the first strength weakening zone 224, which can further improve the timeliness and accuracy of the tearing or breaking at the position of the notch groove 25 when the first strength weakening zone 224 reaches the failure condition, thereby improving the reliability of the battery cell 20.

[0150] The arrangement of multiple notch groove groups and multiple notch grooves 25 can increase the locations where tearing or breaking may occur. The circumferential groove wall of each notch groove 25 may be torn or broken due to tensile force, which can meet the strength requirements of the connection and fixation of the electrode assembly 21 in the unexpanded state, while taking into account the requirement that the electrode assembly 21 can be free from constraints and expand freely after expanding to a certain proportion.

[0151] According to some embodiments of the present application, along the first direction, the first limiting portion 221 includes a stacked first adhesive layer 2212 and a first substrate layer 2211, and the two sides of the first adhesive layer 2212 are respectively connected to the first end face 211 and the first substrate layer 2211; along the first direction, the second limiting portion 222 includes a stacked second adhesive layer 2222 and a second substrate layer 2221, and the two sides of the second adhesive layer 2222 are respectively connected to the second end face 212 and the second substrate layer 2221.

[0152] The primary function of the first and second substrate layers 2211, 2221, is to provide structural strength to the first and second limiting portions 221, 222. This allows the first limiting member 22 to securely connect the electrode assembly 21, securing the internal structure of the electrode assembly 21 to a fixed position, facilitating overall transport, transfer, and placement into a battery case. Furthermore, the adhesive bonding between the first limiting portion 221 and the first end face 211, and between the second limiting portion 222 and the second end face 212, facilitates the manufacture of the battery cell 20 and reduces manufacturing costs.

[0153] The first adhesive layer 2212 bonds the first base material layer 2211 and the first end surface 211 together, and the second adhesive layer 2222 bonds the second base material layer 2221 and the second end surface 212 together.

[0154] In the above scheme, the first limiting portion 221 and the first end face 211 are connected by bonding, and the second limiting portion 222 and the second end face 212 are also connected by bonding. This can protect the surface structure of the first end face 211 and the second end face 212, and can effectively reduce the damage of the first limiting portion 221 and the second limiting portion 222 to the electrode assembly 21 when the electrode assembly 21 undergoes a large volume expansion due to temperature increase, thereby protecting the electrode assembly 21, reducing the probability of failure of the electrode assembly 21 due to structural damage, and helping to improve performance stability and reliability.

[0155] According to some embodiments of the present application, along the second direction, the third limiting portion 223 includes a stacked third substrate layer 2231 and a third adhesive layer 2232, the two sides of the third adhesive layer 2232 are respectively connected to the third end face 213 and the third substrate layer 2231, and at least a portion of the notched groove 25 is arranged on the third substrate layer 2231; the third substrate layer 2231 is connected to the first substrate layer 2211 and the second substrate layer 2221, and the third adhesive layer 2232 is connected to the first adhesive layer 2212 and the second adhesive layer 2222.

[0156] The third substrate layer 2231 serves as the main strength structural component of the third limiting portion 223. After being connected with the first substrate layer 2211 and the second substrate layer 2221, they jointly connect and fix the electrode assembly 21 as a whole, so that the relative position between the internal structures of the electrode assembly 21 is fixed, so as to facilitate the overall transportation, transfer, shelling, etc.

[0157] The third adhesive layer 2232 bonds the third base material layer 2231 and the third end surface 213 together, and at the same time connects the first adhesive layer 2212 and the second adhesive layer 2222, so that when the relative positions of the first limiting portion 221 and the second limiting portion 222 change, it can act on the third limiting portion 223 and stretch the third limiting portion 223.

[0158] In the above scheme, the third limiting portion 223 and the third end face 213 also adopt an adhesive connection scheme, and the first limiting portion 221, the second limiting portion 222 and the third limiting portion 223 are all bonded to the corresponding first end face 211, the second end face 212 and the third end face 213, so that the first limiting portion 221, the second limiting portion 222 and the third limiting portion 223 can all respond to the relative position change of the first end face 211 and the second end face 212 in the first direction when the electrode assembly 21 expands, so that when the third limiting portion 223 is stretched, in addition to being subjected to the tensile force of the first limiting portion 221 and the second limiting portion 222, it is also subjected to the resistance of the third end face 213, thereby increasing the force form of the first strength weakening zone 224. At least a portion of the notched groove 25 is disposed on the third substrate layer 2231, that is, the notched groove 25 is primarily used to reduce the tensile strength of the third substrate layer 2231 in the first strength weakening region 224, so that the third substrate layer 2231 can be torn under preset conditions, thereby enabling the first strength weakening region 224 to better respond to changes in the expansion coefficient of the electrode assembly 21 along the first direction, so as to be able to tear or break in a timely manner.

[0159] It should be noted that when adopting the scheme of bonding the first limiting member 22 to the electrode assembly 21, since the third limiting portion 223 is bonded to the third end face 213, and the projection of the notched groove 25 along the second direction is to fall within the projection of the third end face 213, the opening of the notched groove 25 is located in the second direction, and the opening can be facing the third end face 213 or away from the third end face 213.

[0160] The materials of the first substrate layer 2211, the second substrate layer 2221, and the third substrate layer 2231 can be selected based on actual needs. It is only necessary that the third substrate layer 2231 can be torn or broken at the notched groove 25 in response to the expansion of the electrode assembly 21 in the first direction under predetermined conditions. For example, in some embodiments, the third substrate layer 2231 can be made of PET. PET (polyester) is a thermoplastic resin made of polyethylene terephthalate (PETP) or polytrimethylene terephthalate (PETG). PET has excellent physical properties, such as high strength, high transparency, good wear resistance, and good chemical resistance.

[0161] In some embodiments, the material of the first substrate layer 2211 , the second substrate layer 2221 , and the third substrate layer 2231 may also be PP or other materials.

[0162] The materials of the first substrate layer 2211 and the second substrate layer 2221 may be the same as or different from those of the third substrate layer 2231 , which is not specifically limited in this embodiment.

[0163] In addition, in addition to the above-mentioned scheme of bonding the first limiter 22 to the electrode assembly 21, according to other embodiments of the present application, the first limiter 22 can also be a rigid structure with a certain structural strength, such as a clamp-like shape, which can fix the electrode assembly 21 under non-expansion conditions and limit the relative movement of the internal structure of the electrode assembly 21. When the electrode assembly 21 expands, the first strength weakening zone 224 breaks under preset conditions and releases the restraint on the electrode assembly 21, so that the electrode assembly 21 can be free from resistance in the thickness direction.

[0164] According to some embodiments of the present application, the thickness of the third substrate layer 2231 is h, which satisfies: 5 μm≤h≤50 μm.

[0165] The thickness h of the third substrate layer 2231 can be 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 25 μm, 30 μm, 35 μm, 37 μm, 39 μm, 43 μm, 45 μm, 48 μm, 50 μm, etc.

[0166] In the above solution, the overall strength of the third stopper 223 is primarily determined by the third substrate layer 2231. The specific structural design of the first weakened zone 224 is also related to the structural strength of the third substrate layer 2231. Whether the first weakened zone 224 can be promptly broken is also primarily determined by the substrate layer. By setting the thickness of the third substrate layer 2231 between 5μm and 50μm, on the one hand, the dimensions of the first stopper 22 in the second direction can be controlled within a relatively small range, thereby effectively controlling the combined dimensions of the first stopper 22 and electrode assembly 21 in the second direction. This facilitates controlling the overall dimensions of the battery cell 20 in the second direction and improves the spatial energy density of the battery 100. On the other hand, the relatively small thickness of the third substrate layer 2231 allows the formation of the notched grooves 25 in the third substrate layer 2231 to reduce the thickness of the first weakened zone 224, effectively reducing the tensile strength of the first weakened zone 224 and enabling the third substrate layer 2231 to tear under predetermined conditions.

[0167] According to some embodiments of the present application, the electrode assembly 21 further includes a fourth end surface 214, which is connected to the other end of the first end surface 211 and the second end surface 212 on the same side in the second direction. The battery cell 20 further includes a second retaining member 23, which includes a fourth retaining portion 231, a fifth retaining portion 232, and a sixth retaining portion 233. The fourth retaining portion 231 is connected to the first end surface 211, the fifth retaining portion 232 is connected to the second end surface 212, and the sixth retaining portion 233 connects the fourth retaining portion 231 and the fifth retaining portion 232. The sixth retaining portion 233 is arranged opposite the fourth end surface 214 in the second direction. The sixth retaining portion 233 is provided with a second strength reduction zone 234 to prevent the third retaining portion 223 from tearing when the expansion coefficient of the electrode assembly 21 in the first direction exceeds a preset value.

[0168] As shown in Figures 3 to 6, the second direction is the X direction, that is, the width direction of the electrode assembly 21. The electrode assembly 21 has a first end 215 and a second end 216 opposite to each other in the second direction. The fourth end surface 214 is connected to the other end of the first end surface 211 and the second end surface 212 on the same side in the second direction. Here, the other end on the same side refers to the end of the first end surface 211 corresponding to the second end 216 and the end of the second end surface 212 corresponding to the first end 215. In other words, one end of the fourth end surface 214 in the first direction is connected to the end of the first end surface 211 corresponding to the second end 216, and the other end of the fourth end surface 214 in the first direction is connected to the end of the second end surface 212 corresponding to the second end 216. In other words, the third end surface 213 and the fourth end surface 214 are two opposite end surfaces of the electrode assembly 21 in the second direction.

[0169] In the above scheme, in the second direction, the third end face 213 and the fourth end face 214 are located at the opposite ends of the first end face 211 and the second end face 212, and the second limiter 23 and the first limiter 22 are also located at the opposite ends of the first end face 211 and the second end face 212, that is, the end where the third end face 213 is located is connected and fixed to the electrode assembly 21 by the first limiter 22, and the end where the fourth end face 214 is located is connected and fixed to the electrode assembly 21 by the second limiter 23, the first limiter 22 and the second limiter 23 act together on the electrode assembly 21 to connect and fix the electrode assembly 21 as a whole, limit the relative position between the internal structures of the electrode assembly 21, and improve the connection and fixing effect.

[0170] The working principle of the first limiting member 22 is the same as that of the first limiting member 22. By setting the second strength weakening area 234 on the sixth limiting portion 233, the tensile strength of the entire sixth limiting portion 233 is reduced. The sixth limiting portion 233 is opposite to the fourth end face 214 in the second direction, and the second strength weakening area 234 is also located in the thickness direction of the electrode assembly 21. When the electrode assembly 21 is heated or expands due to thermal runaway, the relative positions of the first end face 211 and the second end face 212 in the first direction are in a relationship. When the expansion coefficient of the electrode assembly 21 in the first direction exceeds a preset value, the first end face 211 and the second end face 212 are in a relationship. 12 increases and stretches the sixth limiting portion 233, causing the sixth limiting portion 233 to be torn or broken by part of the second strength weakening zone 234, and the force of the second limiting member 23 on the first end face 211 and the second end face 212 is reduced or reduced to zero, so that the restraining effect of the second limiting member 23 on the electrode assembly 21 in the first direction fails, so that the diaphragm and the electrode piece of the electrode assembly 21 can adaptively expand in the first direction, thereby protecting the diaphragm and the electrode piece, reducing the probability of tearing the diaphragm and the electrode piece and the probability of overall failure of the electrode assembly 21, thereby improving the reliability and safety performance of the battery 100.

[0171] The number of the second limiting member 23 can be one or more.

[0172] According to some embodiments of the present application, the first limiting portion 221 is connected to the fourth limiting portion 231 , the second limiting portion 222 is connected to the fifth limiting portion 232 , and the first limiting member 22 and the second limiting member 23 are an integrally formed part.

[0173] The first limiting member 22 and the second limiting member 23 are integrally formed. This may mean that after the first limiting member 22 and the second limiting member 23 are integrally formed, since the first limiting portion 221 is connected to the fourth limiting portion 231, and the second limiting portion 222 is connected to the fifth limiting portion 232, a closed coil structure is directly formed. This may also mean that the first limiting portion 221 and the fourth limiting portion 231 are integrally formed, and the first limiting member 22 and the second limiting member 23 are both flexible structures with adhesiveness (such as the above-mentioned substrate layer and adhesive layer). At this time, the first limiting member 22 and the second limiting member 23 are integrally formed to form a structure similar to adhesive tape, and then the electrode assembly 21 is bonded and fixed by winding in the circumferential and thickness directions of the electrode assembly 21, and the winding method is a full circle winding, for example, the second limiting portion 222 is first bonded to the second end face 212, and the fifth limiting portion 232 is finally bonded to the second end face 212, and the fifth limiting portion 232 needs to extend to the second limiting portion 222 and bonded to the second limiting portion 222 to complete the full circle of glue winding.

[0174] In the above scheme, the first limiting member 22 and the second limiting member 23 are integrally wound around the electrode assembly 21, and the first strength weakening area 224 and the second strength weakening area 234 are respectively provided on the third limiting portion 223 and the sixth limiting portion 233 located in the thickness direction, so that the first strength weakening area 224 and the second strength weakening area 234 are stretched as the electrode assembly 21 expands in the first direction. The third limiting portion 223 and the sixth limiting portion 233 can be torn when the expansion coefficient of the electrode assembly 21 along the first direction exceeds a preset value, and then the electrode assembly 21 is no longer constrained in the first direction, that is, the thickness direction, and can expand freely, which can effectively protect the structure of the electrode assembly 21 and improve the reliability and safety performance of the battery cell 20.

[0175] In addition, it should be noted that, as shown in Figure 3, in addition to setting the first limit member 22 and the second limit member 23 at both ends of the electrode assembly 21 in the second direction, a third limit member 24 can also be set at at least one end of the electrode assembly 21 along the third direction as needed. A third strength weakening area 241 is also set on the third limit member 24 to prevent tearing and breaking after the expansion coefficient of the electrode assembly 21 exceeds a preset range. The structure and principle of the third limit member 24 can refer to the first limit member 22 and the second limit member 23, and will not be repeated here.

[0176] According to some embodiments of the present application, the second direction is the length direction or the width direction of the electrode assembly 21 .

[0177] In the above scheme, the second direction is the length direction or the width direction of the electrode assembly 21, and the third end face 213 is located at one end of the length direction of the electrode assembly 21, or at one end of the width direction of the electrode assembly 21, that is, the third limiting portion 223 is arranged on one side of the length direction or one side of the width direction of the electrode assembly 21. The first limiting member 22 can more stably connect and fix the electrode assembly 21, and can also more accurately sense the dimensional changes of the electrode assembly 21 in the first direction, that is, the thickness direction, which is conducive to improving the accuracy and reliability of timely tearing and breaking of the third limiting portion 223.

[0178] According to some embodiments of the present application, the electrode assembly 21 is a wound electrode assembly 21 or a laminated electrode assembly 21 .

[0179] In the above embodiment, when the electrode assembly 21 is a wound electrode assembly 21, the electrode assembly 21 is wound to form a multi-layer structure, and the first direction is the stacking direction of the multi-layer structure, that is, the direction outward from the winding center axis. When the electrode assembly 21 is a laminated electrode assembly 21, the first direction is the stacking direction of the electrode sheets and separators alternately stacked. The principle of the lamination process determines that the electrode sheets and separators of the battery cell will not bend during the manufacturing process, and can be fully unfolded and stacked together, which not only reduces the internal resistance of the battery cell and increases the battery cell power, but also improves the energy density of the battery 100.

[0180] Regardless of whether it is a wound electrode assembly 21 or a laminated electrode assembly 21, the overall shape and structure of the electrode assembly 21 are relatively regular, which facilitates the setting of the first limiting member 22 to smoothly connect the first limiting portion 221 and the first end face 211, and connect the second limiting portion 222 and the second end face 212.

[0181] According to some embodiments of the present application, the battery cell 20 further includes a shell, which is provided with a receiving cavity, and the electrode assembly 21 and the first limiting member 22 are both provided in the receiving cavity.

[0182] In the above embodiment, the outer shell provides a housing for the electrode assembly 21 connected to the first retaining member 22. The housing also accommodates electrolyte and other components, making it easy to insert the entire electrode assembly 21 into the outer shell after being connected and fixed by the first retaining member 22. In addition, the outer shell has a certain hardness and strength, making it less likely to deform when squeezed or collided, thereby providing the battery cell 20 with higher structural strength and improved safety performance.

[0183] According to some embodiments of the present application, the present application further provides a battery 100 , which includes the battery cell 20 as described above.

[0184] According to some embodiments of the present application, the present application further provides an electrical device, which includes the battery cell 20 and / or battery 100 as described above, and the battery cell 20 and / or battery 100 is used to provide electrical energy.

[0185] According to some embodiments of the present application, referring to Figures 3 to 9, the present application provides a battery cell 20, including an electrode assembly 21, a first limiting member 22, a second limiting member 23 and a third limiting member 24. The electrode assembly 21 is a laminated electrode assembly 21 with a generally square structure. The first limiting member 22 and the second limiting member 23 are respectively arranged at the two ends of the electrode assembly 21 in the second direction. The first limiting member 22 connects the first end face 211, the third end face 213 and the second end face 212. The second limiting member 23 connects the first end face 211, the fourth end face 214 and the second end face 215. 212, the first limiting member 22 includes an integrally formed first limiting portion 221, a second limiting portion 222 and a third limiting portion 223. Along the first direction, the first limiting portion 221 includes a stacked first adhesive layer 2212 and a first substrate layer 2211, and the two sides of the first adhesive layer 2212 are respectively connected to the first end face 211 and the first substrate layer 2211; along the first direction, the second limiting portion 222 includes a stacked second adhesive layer 2222 and a second substrate layer 2221, and the two sides of the second adhesive layer 2222 are respectively connected to the second end face 212 and the second substrate layer 2221. Along the second direction, the third position-limiting portion 223 includes a stacked third substrate layer 2231 and a third adhesive layer 2232. Two sides of the third adhesive layer 2232 are connected to the third end surface 213 and the third substrate layer 2231, respectively. In other words, the first substrate layer 2211, the second substrate layer 2221, and the third substrate layer 2231 are integrally formed, and the first adhesive layer 2212, the second adhesive layer 2222, and the third adhesive layer 2232 are integrally formed. In other words, the first position-limiting member 22 as a whole forms a structure similar to adhesive tape.

[0186] The first substrate layer 2211, the second substrate layer 2221, and the third substrate layer 2231 are made of PET substrates. The third limiting portion 223 is opposite the third end surface 213. The third limiting portion 223 is provided with a plurality of score grooves 25 spaced along the third direction. The projections of the score grooves 25 in the second direction all fall on the third end surface 213. The score grooves 25 are located in the thickness direction and are provided at least in the third substrate layer 2231. This reduces the tensile strength of the PET substrate, thereby reducing the tensile strength of the first limiting portion 221 in the first direction. The score grooves 25 can be circular, square, diamond, elliptical, or other shapes.

[0187] As shown in Figures 5 and 9, five notched grooves 25 are provided on the third limiting portion 223 of the two first limiting members 22. The five notched grooves 25 have the same size and are arranged in a row in the third direction (i.e., the length direction of a single notched groove 25). The size of a single notched groove 25 in the third direction is L, and the sum D1 of the sizes corresponding to the five notched grooves 25 in the third limiting portion 223 is numerically equal to the sum of the five Ls.

[0188] The third limiting member 24 is provided at at least one end of the electrode assembly 21 along the third direction. The third limiting member 24 is similar in structure and principle to the first limiting member 22 and the second limiting member 23 , and will not be described in detail here.

[0189] According to the requirements of safety performance, the volume expansion ratio or thickness expansion ratio of the electrode assembly 21 in the first direction when the first limiter 22 is broken by the first strength weakening zone 224 can be determined, and then the tensile strength of the first strength weakening zone 224 can be determined. According to the tensile strength, the number of notched grooves 25, the length dimension L of the notched grooves 25 in the third direction, the width dimension W of the notched grooves 25 in the first direction, the spacing between two adjacent notched grooves 25 in the third direction, etc. can be selected accordingly.

[0190] When the size of the electrode assembly 21 in the first direction expands to a certain proportion, the third limiting portion 223 is stretched to a certain extent, reaching the tensile strength limit of the first strength weakening zone 224, the second strength weakening zone 234 and the third strength weakening zone 241, and the first limiting member 22, the second limiting member 23 and the third limiting member 24 are broken at the position of the notched groove 25, losing the restraining effect on the electrode assembly 21, and the positive electrode sheet, the negative electrode sheet and the diaphragm of the electrode assembly 21 can expand freely, thereby improving the reliability of the battery 100 during use.

[0191] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A battery cell, comprising: An electrode assembly, including a first end face, a second end face and a third end face. Along a first direction, the first end face and the second end face are oppositely arranged, and the third end face is connected to the same-side end of the first end face and the second end face in a second direction. The first direction is the thickness direction of the electrode assembly, and the second direction is perpendicular to the thickness direction of the electrode assembly; A first limiting member, including a first limiting portion, a second limiting portion and a third limiting portion. The first limiting portion is connected to the first end face, the second limiting portion is connected to the second end face, the third limiting portion connects the first limiting portion and the second limiting portion, and the third limiting portion is oppositely arranged to the third end face in the second direction; Wherein, a first strength weakening area is provided on the third limiting portion, so that the third limiting portion tears when the expansion coefficient of the electrode assembly along the first direction exceeds a preset value.

2. The battery cell according to claim 1, wherein, The first strength weakening area includes a notch groove. Along the second direction, the projection of the notch groove falls within the projection of the third end face.

3. The battery cell according to claim 2, wherein, The length direction of the notch groove has an included angle with the first direction.

4. The battery cell according to claim 3, wherein, Along the length direction of the notch groove, the notch groove penetrates through both ends of the third limiting portion.

5. The battery cell according to any one of claims 2-4, wherein, There are multiple notch grooves, and the multiple notch grooves are arranged at intervals along a third direction. The third direction has an included angle with the second direction.

6. The battery cell according to claim 5, wherein, The third direction is the length direction of the notch groove, and the dimension of the notch groove in the third direction is L, satisfying: 0.01 mm ≤ L ≤ 10 mm.

7. The battery cell according to claim 6, wherein, 0.05 mm ≤ L ≤ 2 mm.

8. The battery cell according to any one of claims 5-7, wherein, The sum of the dimensions of the multiple notch grooves in the third direction is D1, and the dimension of the third limiting portion in the third direction is D2, satisfying: 0.3 ≤ D1 / D2 ≤ 0.

9.

9. The battery cell according to any one of claims 5-7, wherein, The dimension of the notch groove in a fourth direction is W, satisfying: 0.01 mm ≤ W ≤ 8 mm. The fourth direction is the width direction of the notch groove and has an included angle with the third direction.

10. The battery cell according to claim 9, wherein, 0.02 mm ≤ W ≤ 2 mm.

11. The battery cell according to any one of claims 1-10, wherein, The first strength weakening area includes multiple notch groove groups. Each notch groove group includes multiple notch grooves arranged at intervals along a third direction. The third direction has an included angle with the second direction, and the multiple notch groove groups are spaced apart in a fourth direction. The fourth direction is perpendicular to the third direction.

12. The battery cell according to any one of claims 2-11, wherein, Along the first direction, the first limiting portion includes a first adhesive layer and a first base material layer stacked on each other. The two sides of the first adhesive layer are respectively connected to the first end face and the first base material layer; Along the first direction, the second limiting portion includes a second adhesive layer and a second base material layer stacked on each other. The two sides of the second adhesive layer are respectively connected to the second end face and the second base material layer.

13. The battery cell according to claim 12, wherein, Along the second direction, the third limiting portion includes a third base material layer and a third adhesive layer stacked on each other. The two sides of the third adhesive layer are respectively connected to the third end face and the third base material layer, and at least part of the notch groove is arranged in the third base material layer; The third base material layer connects the first base material layer and the second base material layer, and the third adhesive layer connects the first adhesive layer and the second adhesive layer.

14. The battery cell according to claim 13, wherein, The thickness of the third base material layer is h, satisfying: 5μm ≤ h ≤ 50μm.

15. The battery cell according to any one of claims 1-14, wherein, The electrode assembly further includes a fourth end face, and the fourth end face is connected to the other end on the same side of the first end face and the second end face in the second direction; The battery cell further includes a second limiting member, the second limiting member includes a fourth limiting portion, a fifth limiting portion and a sixth limiting portion, the fourth limiting portion is connected to the first end face, the fifth limiting portion is connected to the second end face, the sixth limiting portion connects the fourth limiting portion and the fifth limiting portion, and the sixth limiting portion is disposed opposite to the fourth end face in the second direction; Wherein, a second strength weakening area is provided on the sixth limiting portion, so that the third limiting portion tears when the expansion coefficient of the electrode assembly in the first direction exceeds a preset value.

16. The battery cell according to claim 15, wherein, The first limiting portion is connected to the fourth limiting portion, the second limiting portion is connected to the fifth limiting portion, and the first limiting member and the second limiting member are integrally formed.

17. The battery cell according to any one of claims 1-16, wherein, The second direction is the length direction or the width direction of the electrode assembly.

18. The battery cell according to any one of claims 1-16, wherein, The electrode assembly is a wound electrode assembly or a stacked electrode assembly.

19. The battery cell according to any one of claims 1-16, wherein, The battery cell further includes a housing, the housing is provided with a receiving cavity, and the electrode assembly and the first limiting member are both disposed in the receiving cavity.

20. A battery, comprising the battery cell according to any one of claims 1-19.

21. An electrical device, comprising the battery cell according to any one of claims 1-19 and / or the battery according to claim 20, and the battery cell and / or the battery are used to provide electrical energy.

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