Battery monomer, battery and electric device

Abstract

The utility model discloses a battery monomer, a battery and an electric device. The battery monomer comprises a shell, a battery cover and a battery cover, the electrode assembly is arranged in the shell and comprises an isolating membrane and a pole piece, the isolating membrane and the pole piece are stacked and wound, and a central space is formed in the central position of the electrode assembly; and the buffer piece comprises a buffer part and an extension part, the buffer part is arranged in the central space, and the extension part is located outside the central space and arranged between the shell and the electrode assembly. According to the electrode assembly, the probability of brittle failure during hot pressing of the winding structure can be reduced, the probability of burr occurrence can be reduced, the distance between the pole pieces at the corner of the innermost ring of the electrode assembly can be reduced, the probability of large gaps between the pole pieces at the corner of the innermost ring of the electrode assembly can be reduced, and the probability of lithium precipitation can be reduced. The electrode assembly and the shell can be separated by the extension part, so that the probability of collision between the electrode assembly and the shell when the electrode assembly is assembled in the shell is reduced, and the reliability of the battery monomer can be improved.

Description

Technical Field

[0001] 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

[0002] In recent years, new energy vehicles have developed by leaps and bounds. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. The battery consists of a box and multiple battery cells contained in the box. Among them, batteries, as core components of new energy vehicles, have high requirements in terms of reliability and service life. However, in the core-type battery cells, there are reliability problems with the internal core, which seriously affects the reliability of the battery cells. Utility Model Content

[0003] The embodiments of the present application provide a battery cell, a battery, and an electrical device, which can effectively improve the reliability of the battery cell, thereby improving the reliability of the battery.

[0004] In a first aspect, an embodiment of the present application provides a battery cell, comprising: a shell; an electrode assembly, the electrode assembly is disposed in the shell and comprises an isolation membrane and a pole piece, the isolation membrane and the pole piece are stacked and wound, and a central space is formed at the center of the electrode assembly; a buffer, comprising a buffer portion and an extension portion, the buffer portion is disposed in the central space, the extension portion is located outside the central space, and is disposed between the shell and the electrode assembly.

[0005] In the above technical solution, by setting a buffer including a buffer part and an extension part, the buffer part is arranged in the central space formed by the isolation membrane and the pole piece winding and plays a buffering role, thereby supporting the innermost pole piece when the winding core structure formed by the isolation membrane and the pole piece is hot pressed, reducing the probability of brittle fracture during hot pressing of the winding structure, and reducing the probability of burrs. Moreover, under the support of the buffer part, the pole piece spacing at the innermost corner of the electrode assembly can be reduced, and the probability of a large gap between the pole pieces at the innermost corner of the electrode assembly can be reduced, thereby reducing the probability of lithium deposition, thereby improving the reliability of the electrode assembly, and further improving the reliability of the battery cell. By setting the extension part between the shell and the electrode assembly, the extension part separates the electrode assembly and the shell, reducing the probability of collision between the electrode assembly and the shell when assembled into the shell, and reducing the probability of damage to the electrode assembly, thereby further improving the reliability of the battery cell.

[0006] In some embodiments of the present application, the extension portion includes: a heat-conductive substrate, the heat-conductive substrate is connected to the buffer portion, and is fitted to the housing.

[0007] In the above technical solution, by configuring the extension portion to include a heat-conducting substrate, the extension portion can also have a heat-conducting effect and can increase the heat exchange surface area between the electrode assembly and the outer shell, thereby quickly transferring the heat inside the electrode assembly to the outer shell, improving the heat dissipation efficiency, being beneficial to the cooling of the battery cell, and effectively reducing the temperature rise of the battery cell, reducing the side reactions inside the battery, which is beneficial to slowing down the battery capacity attenuation, and can improve the reliability and performance of the battery cell.

[0008] In some embodiments of the present application, the extension portion further includes: an insulating portion, which is disposed on a side of the heat-conductive substrate close to the electrode assembly and is attached to the electrode assembly.

[0009] In the above technical solution, by configuring the extension portion to also include an insulating portion, the extension portion can also have an insulating effect, thereby reducing the probability of electrical connection between the electrode assembly and the shell, and also reducing the probability of short circuit between the electrode assembly and the shell, thereby improving the reliability of the battery cell.

[0010] In some embodiments of the present application, a protrusion is provided at one end of the insulating portion close to the buffer portion, and the protrusion is arranged around the circumference of the buffer portion.

[0011] In the above technical solution, by providing the insulating part with a protrusion, the protrusion can play an insulating and protective role in the connection area between the heat-conducting substrate and the buffer part, reducing the probability of the connection area between the heat-conducting substrate and the buffer part being exposed, thereby reducing the probability of short circuit caused by contact with the connection area of ​​the heat-conducting substrate when the end of the pole piece is folded or damaged, thereby improving the reliability of the battery cell.

[0012] In some embodiments of the present application, the protruding height of the protruding portion is H1, wherein 0mm≤H1≤5mm.

[0013] In the above technical solution, by setting the protrusion height H1 of the protrusion within the range of 0mm to 5mm, the protrusion can have an appropriate height, which can effectively separate the end area of ​​the pole piece from the connection area of ​​the heat conductive substrate and the buffer portion, thereby having a better insulation protection effect, and can also reduce the manufacturing cost of the protrusion.

[0014] In some embodiments of the present application, the thickness of the insulating portion is T1, wherein 0.1 mm≤T1≤1 mm.

[0015] In the above technical solution, by setting the thickness T1 of the insulating part within the range of 0.1mm to 1mm, the thickness T1 of the insulating part is within an appropriate range. While having a good insulation effect, the thickness of the insulating part can be not too thick. On the one hand, it can reduce the cost, and on the other hand, it is beneficial to reduce the overall thickness of the extension part and increase the volume share of the electrode assembly, which is beneficial to increase the volume energy density of the battery cell.

[0016] In some embodiments of the present application, the thickness of the thermally conductive substrate is T2, wherein 0.1 mm≤T2≤1 mm.

[0017] In the above technical solution, by setting the thickness T2 of the thermally conductive substrate 2321 within the range of 0.1 mm to 1 mm, the thickness T2 of the thermally conductive substrate 2321 is within an appropriate range. While having better support and thermal conductivity effects, the thickness of the thermally conductive substrate 2321 can be made not too thick. On the one hand, it can reduce costs, and on the other hand, it is beneficial to improve the energy density of the battery cell 20.

[0018] In some embodiments of the present application, the extension portion and the buffer portion are separate structures, and the extension portion and the buffer portion are connected by bonding or thermal bonding.

[0019] In the above technical solution, by setting the extension part and the buffer part as a separate structure, it is beneficial for the extension part to adopt a structure different from the buffer part and have a function different from the buffer part, which is beneficial to expand the function of the buffer. On the other hand, the extension part and the buffer part can also be of the same structure, but because the extension part and the buffer part are separate structures, the extension part and the buffer part can be manufactured separately, which can reduce the difficulty of manufacturing the buffer part and help reduce the manufacturing cost.

[0020] In some embodiments of the present application, the extension portion and the buffer portion are an integrally formed part.

[0021] In the above technical solution, by setting the extension part and the buffer part as an integrally formed part, the structure of the buffer part is more stable, the probability of separation between the extension part and the buffer part is relatively low, and it is convenient to assemble the extension part and the buffer part to the electrode assembly, and it is also convenient to assemble the buffer part and the electrode assembly together into the shell, which can improve the assembly efficiency of the battery cell. In addition, since the extension part and the buffer part are an integrally formed part, the extension part is not easy to be displaced in the shell, which can improve the reliability of the extension part in the shell, and thus help improve the reliability of the battery cell.

[0022] In some embodiments of the present application, the isolation film and the pole piece are wound in a first direction, a pole ear is provided at one end of the pole piece along the first direction, and the extension portion is provided on a side of the electrode assembly away from the pole ear.

[0023] In the above technical solution, since the extension part and the pole ear are located at both ends of the electrode assembly, the probability of mutual influence between the extension part and the pole ear is relatively low, which facilitates bending the pole ear at one end of the pole piece and also facilitates the connection between the pole ear and the pole column. In addition, the extension part will not be affected by the pole piece, so on the one hand, it is convenient to arrange the extension part, and on the other hand, the size of the extension part can be set relatively large, which can better support the electrode assembly.

[0024] In some embodiments of the present application, the electrode tab is located at the top of the electrode assembly, and the extension portion is located at the bottom of the electrode assembly and supported by the housing.

[0025] In the above technical solution, the extension part can play the role of a bottom support plate, supporting the electrode assembly in the shell, and has a "one thing for two purposes" function. In this way, there is no need to set up a bottom support plate, which can reduce costs and reduce the bottom support plate into the shell process, which is conducive to improving assembly efficiency. Since the buffer part is located in the central space of the electrode assembly and the extension part is connected to the buffer part, the position of the extension part and the electrode assembly is relatively fixed, which can reduce the sliding friction between the electrode assembly and the extension part, thereby reducing the probability of wear of the pole piece and improving the reliability of the electrode assembly.

[0026] In some embodiments of the present application, a shell wall on one side of the shell close to the extension portion is provided with a rounded corner, the radius of the rounded corner is R, and the thickness of the extension portion is T3, wherein 1 / 3R≤T3≤R.

[0027] In the above technical solution, by setting the relationship between the thickness T3 of the extension part and the radius R of the rounded corner of the outer shell within the above range, the extension part can have a more suitable thickness. On the one hand, the electrode assembly can be lifted to a suitable height, reducing the probability of contact between the electrode assembly and the rounded corner of the outer shell, thereby reducing damage to the electrode assembly and improving the reliability of the electrode assembly. On the other hand, it can also help to reduce the volume share of the extension part in the outer shell, which can improve the volume energy density of the battery cell.

[0028] In some embodiments of the present application, the isolation film and the pole piece are wound in a first direction, a pole ear is provided at one end of the pole piece along the first direction, and the extension portion is provided on a side of the electrode assembly close to the pole ear.

[0029] In the above technical solution, the extension portion is arranged on the side of the electrode assembly close to the pole ear, that is, the extension portion and the pole ear are located on the same side of the electrode assembly, so that the extension portion can block the central space and the end face of the pole piece, thereby reducing the probability of the pole ear being inserted into the central space or contacting the pole piece to cause a short circuit when the pole ear is folded, thereby improving the reliability of the electrode assembly, thereby improving the reliability of the battery cell.

[0030] In some embodiments of the present application, the isolation membrane and the pole piece are wound in a first direction, a pole ear is provided at one end of the pole piece along the first direction, and extension portions are provided at both ends of the electrode assembly in the first direction.

[0031] In the above technical scheme, among the extension portions located at both ends of the first direction of the electrode assembly, the one located on the same side of the electrode assembly as the pole ear can play a role of blocking the pole ear and the pole piece, reducing the probability of short circuit caused by electrical connection between the pole ear and the pole piece, and the other one located on the different side of the electrode assembly from the pole ear can play a role of buffer barrier between the electrode assembly and the outer shell, reducing the probability of damage to the pole piece caused by direct contact between the electrode assembly and the outer shell.

[0032] In some embodiments of the present application, the isolation film and the pole piece are wound around a first direction, pole ears are provided at both ends of the pole piece along the first direction, and extension portions are provided at both ends of the electrode assembly located in the first direction.

[0033] In the above technical solution, pole ears are provided at both ends of the electrode assembly, and extension portions are provided at both ends of the buffer portion, and are provided corresponding to the pole ears at both ends of the electrode assembly, thereby reducing the probability of short circuit between the pole ears and pole sheets at both ends of the electrode assembly in the first direction, and improving the reliability of the battery cell.

[0034] In some embodiments of the present application, on a plane perpendicular to the first direction, a projection of an end of the pole ear away from the pole piece on the plane is located within a projection of the extension portion on the plane.

[0035] In the above technical solution, it can be understood that the size of the extension portion is relatively large, and it can also be understood that the area of ​​the extension portion away from the surface of the electrode assembly is relatively large. In this way, when the pole piece is folded at the pole ear, the end of the pole ear away from the pole piece is more easily blocked by the extension portion, and the pole ear is not easy to cross the extension portion and contact other pole pieces, thereby further reducing the probability of electrical connection between the pole ear and the pole piece causing a short circuit.

[0036] In some embodiments of the present application, the electrode ear is located on one side of the extension portion in the third direction, and the electrode assembly has a second direction perpendicular to the third direction. In the second direction, the width of the electrode assembly is D1, the width of the extension portion is D2, and the thickness of the buffer portion is T6, wherein T6<D2≤1 / 2D1.

[0037] In the above technical solution, the width of the extension part is at least greater than the thickness of the buffer part, so that the extension part can block the central space and reduce the probability of the tab being inserted into the central space. By setting the width of the extension part to be less than or equal to one-half of the width of the electrode assembly, the width of the extension part can be prevented from being too long, thereby reducing the influence of the extension part on the tab.

[0038] In some embodiments of the present application, the electrode assembly has a first surface close to the extension portion, the extension portion has a second surface close to the first surface, and the distance between the second surface and the first surface is H2, wherein 1mm≤H2≤3mm.

[0039] In the above technical solution, by setting the distance between the first surface of the electrode assembly close to the extension portion and the second surface of the extension portion close to the first surface to 1mm to 3mm, a suitable space can be provided between the first surface and the second surface. On the one hand, a suitable space can be provided to accommodate the root of the pole ear close to the pole piece. On the other hand, it is beneficial to reduce the height of the extension portion relative to the electrode assembly, thereby reducing the volume of the extension portion, and further reducing the volume share of the extension portion in the outer shell, which is beneficial to make the electrode assembly have a larger volume share in the outer shell, thereby improving the volume energy density of the battery cell.

[0040] In some embodiments of the present application, the electrode assembly has multiple side surfaces, at least one of the multiple side surfaces is a first side surface, the area of ​​the first side surface is larger than the areas of the remaining side surfaces, and the extension portion is provided with a first extension portion extending to the first side surface, and the first extension portion covers the first side surface.

[0041] In the above technical solution, the first extension part can replace the insulating sheet to play an insulating role, separate the electrode assembly from the surrounding parts, play a good insulating role for the electrode assembly, and reduce the probability of damage caused by contact between the electrode assembly and the surrounding parts, which can improve the reliability of the electrode assembly and the reliability of the battery cell. In addition, the first extension part can also reduce the use of insulating sheets in the battery cell, which can reduce costs. At the same time, the first extension part can be relatively fixed with the position of the electrode assembly, thereby facilitating the insertion of the electrode assembly into the shell, which is conducive to improving the assembly efficiency of the battery cell.

[0042] In some embodiments of the present application, the extension portion is further provided with a second extension portion, the second extension portion is connected to the first extension portion, and is located on a side of the electrode assembly close to the pole ear.

[0043] In the above technical solution, the second extension portion can act as a separator between adjacent electrode assemblies, reducing the probability of the electrode ear being inserted into the adjacent electrode assembly when folding the electrode ear, causing electrical connection and short circuit, thereby improving the reliability of the electrode assembly and thus improving the reliability of the battery cell.

[0044] In some embodiments of the present application, the electrode ear is located on one side of the second extension portion in the third direction, the electrode assembly has a second direction perpendicular to the third direction, and in the second direction, the width of the electrode assembly is D1, and the width of the second extension portion is D3, wherein D1≤D3≤3 / 2D1.

[0045] In the above technical solution, by setting the width D1 of the electrode assembly and the width D3 of the second extension part within the above range, the second extension part can have an appropriate width range. On the one hand, the second extension part can have a larger size to block the tabs, reducing the probability of the tabs being inserted into the adjacent electrode assembly when bent, thereby reducing the probability of short circuits in the electrode assembly, and will not affect the welding of the tabs and the poles, which is beneficial to improving the reliability of the battery cell. On the other hand, the volume of the second extension part in the shell will not be too large, which is beneficial to make the electrode assembly have a larger volume in the shell, which is beneficial to improving the volume energy density of the battery cell.

[0046] In some embodiments of the present application, both ends of the buffer portion extend to the corners of the pole piece.

[0047] In the above technical solution, by extending the two ends of the buffer portion to the corners of the pole piece, the buffer portion can provide better support for the innermost pole piece, which is beneficial to further reduce the distance between the two pole pieces at the innermost corner of the electrode assembly, and can further reduce the probability of lithium plating.

[0048] In some embodiments of the present application, the buffer portion includes: an elastic portion and a heat-conducting portion, and the heat-conducting portion is provided on at least one side of the elastic portion close to the pole piece.

[0049] In the above technical solution, by configuring the buffer portion to include an elastic portion and a heat-conducting portion, the buffer portion can not only play a buffering role through the elastic portion to balance the expansion force generated by the electrode assembly, but also play a heat-conducting role through the heat-conducting portion, which is beneficial to quickly dissipate the heat inside the electrode assembly, and is beneficial to improving the heat dissipation efficiency of the battery cell, thereby improving the reliability of the battery cell.

[0050] In some embodiments of the present application, the heat-conducting portion is a heat-conducting layer covering the surface of the elastic portion.

[0051] In the above technical solution, by setting the heat-conducting part as a heat-conducting layer covering the surface of the elastic part, the contact area between the heat-conducting part, the elastic part and the pole piece can be made as large as possible, thereby enabling a larger heat exchange surface area between the heat-conducting part and the pole piece, and the heat transfer efficiency of the heat-conducting part is also higher, so that the heat of the electrode assembly can be transferred to the outer shell more quickly, further improving the heat dissipation efficiency of the battery cell, thereby improving the reliability of the battery cell.

[0052] In some embodiments of the present application, the isolation membrane and the pole piece are wound in a first direction, and in the first direction, the height of the electrode assembly is H3, and the height of the elastic portion is H4, wherein -3mm≤H4-H3≤3mm.

[0053] In the above technical solution, by setting the difference between the height H4 of the elastic part and the height H3 of the electrode assembly within the range of -3mm to 3mm, the elastic part can have a larger support range for the innermost pole piece of the electrode assembly, reducing the probability of stress concentration in the innermost pole piece of the electrode assembly, and at the same time reducing the probability of the elastic part extending too long from the electrode assembly and affecting the battery energy density. Secondly, the above solution can also make the elastic part have a suitable processing tolerance range, which is conducive to the processing and manufacturing of the elastic part, can reduce the manufacturing difficulty of the elastic part, and improve the product yield.

[0054] In some embodiments of the present application, the elastic portion has a third surface at one end away from the extension portion, and the heat conductive portion has a fourth surface at one end away from the extension portion. In the first direction, the height difference between the third surface and the fourth surface is H5, where 0mm≤H5≤5mm.

[0055] In the above technical scheme, by setting the difference between the third surface of the elastic part and the fourth surface of the heat-conducting part within the range of 0mm to 5mm, the influence of the excess elastic part of the heat-conducting part on the pole ear can be reduced, as well as the large space occupied in the outer shell, which affects the energy density of the battery cell. At the same time, the probability of a large gap between the elastic part and the innermost pole piece can be reduced, thereby reducing the probability of stress concentration in the electrode assembly and improving the reliability of the battery cell.

[0056] In some embodiments of the present application, the thickness of the elastic portion is T4, wherein 0.5 mm ≤ T4 ≤ 3 mm.

[0057] In the above technical solution, by setting the thickness T4 of the elastic part within the range of 0.5mm to 3mm, the elastic part occupies a relatively small space while ensuring support. In other words, the elastic part can have a relatively high strength, which can provide better support for the innermost pole piece of the electrode assembly. At the same time, the thickness of the elastic part can also be made more appropriate, which is beneficial to improving the energy density of the battery cell.

[0058] In some embodiments of the present application, the thickness of the heat conductive portion is T5, wherein 10 μm≤T5≤500 μm.

[0059] In the above technical solution, by setting the thickness T5 of the heat-conducting part in the range of 10μm to 500μm, the thickness of the heat-conducting part is within an appropriate range, and the heat-conducting part occupies a relatively small space while ensuring thermal conductivity. In other words, the heat-conducting part can have a better thermal conductivity effect, and the thickness of the heat-conducting part and the elastic part is relatively appropriate, which is beneficial to improving the energy density of the battery cell.

[0060] In a second aspect, an embodiment of the present application further provides a battery, comprising the battery cell described above.

[0061] In the above technical solution, since the battery cell has high reliability, the battery having the battery cell can also have high reliability, which can reduce the probability of battery failure during use and improve the performance of the battery.

[0062] In a third aspect, an embodiment of the present application further provides an electrical device, comprising the battery cell or battery as described above.

[0063] In the above technical solution, since the battery cells and batteries have high reliability, the electrical devices having the battery cells or batteries can also have high power reliability, which can reduce the probability of power failure during use of the electrical devices and improve the performance of the electrical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0065] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0066] Figure 2 An exploded view of the structure of a battery provided in some embodiments of the present application;

[0067] Figure 3 A schematic diagram of the internal structure of a battery cell provided in some embodiments of the present application;

[0068] Figure 4 A schematic diagram of assembling an electrode assembly and a buffer portion provided in some embodiments of the present application;

[0069] Figure 5 A schematic diagram of a partial structure of a battery cell provided in some embodiments of the present application;

[0070] Figure 6 A schematic diagram of the structure of a buffer provided in some embodiments of the present application;

[0071] Figure 7 for Figure 6 A local enlarged schematic diagram of location I;

[0072] Figure 8 Provides a schematic diagram of the three-dimensional structure of the electrode assembly and the buffer after assembly for some embodiments of the present application Figure 1 ;

[0073] Fig. 9Provides a side view of the electrode assembly and the buffer after assembly for some embodiments of the present application Figure 1 ;

[0074] Fig.10 Provides a side view of the electrode assembly and the buffer after assembly for some embodiments of the present application Figure 2 ;

[0075] Fig.11 for Fig.10 A local enlarged schematic diagram of location II;

[0076] Fig.12 Provides a schematic diagram of the three-dimensional structure of the electrode assembly and the buffer after assembly for some embodiments of the present application Figure 2 ;

[0077] Fig.13 Provides a side view of the electrode assembly and the buffer after assembly for some embodiments of the present application Figure 3 .

[0078] icon:

[0079] 1000. Vehicles;

[0080] 100. Battery;

[0081] 10. Box body; 11. First box body; 12. Second box body;

[0082] 20. Battery cells;

[0083] 21. housing; 21a. rounded corners;

[0084] 22, electrode assembly; 221, separator; 222, pole piece; 223, pole ear; 22a, central space; 22b, first surface; 22c, first side surface; 223, pole ear;

[0085] 23, buffer; 231, buffer part; 2311, elastic part; 2311a, third surface; 2312, heat conducting part; 2312a, fourth surface; 232, extension part; 232a, second surface; 2321, heat conducting base; 2322, insulating part; 2323, protrusion; 233, first extension part; 234, second extension part;

[0086] 24. Pole;

[0087] 200, controller; 300, motor; X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0088] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0089] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0090] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0091] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0092] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0093] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0094] The term "plurality" used in the present application refers to two or more (including two).

[0095] In the present application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries or magnesium-ion batteries, etc., and the embodiments of the present application do not limit this. Battery cells may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present application do not limit this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application do not limit this.

[0096] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery module or a battery pack. The battery generally includes a box for encapsulating one or more battery cells or multiple battery modules. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

[0097] The battery cell includes a shell, an electrode assembly and an electrolyte, and the shell is used to contain the electrode assembly and the electrolyte. The electrode assembly is composed of a positive electrode sheet, a negative electrode sheet and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode collector, the positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer, and the positive electrode collector not coated with the positive electrode active material layer serves as the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc. The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode collector, the negative electrode collector not coated with the negative electrode active material layer protrudes from the negative electrode collector coated with the negative electrode active material layer, and the negative electrode collector not coated with the negative electrode active material layer serves as the negative electrode tab. The negative electrode current collector may be made of copper, and the negative electrode active material may be carbon or silicon, etc. In order to ensure that a large current is passed without melting, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together.

[0098] The material of the isolation film may be PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly may be a winding structure or a stacked structure, but the embodiments of the present application are not limited thereto.

[0099] In recent years, new energy vehicles have developed by leaps and bounds. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. The battery consists of a box and multiple battery cells contained in the box. Among them, batteries, as core components of new energy vehicles, have high requirements in terms of reliability and cycle life.

[0100] In general core-wound battery cells, the separator separates the positive and negative electrodes and winds them into a core before hot pressing. The innermost negative electrode has a small radius of curvature (almost folded in half), which makes the positive and negative electrodes easy to break. Moreover, due to the high density of the negative electrode and the high coating quality, it is easier to break than the positive electrode. The burr and powder removal after the break can easily cause a short circuit in the battery, reducing the reliability of the battery cell. In addition, since the inner circle of electrodes has no support after winding and pulling the needle, the inner circle is easy to loosen, and the spacing between the 1 to 5 layers of positive and negative electrodes at the corners of the inner circle increases, there is a high probability that the electrodynamics at this position will deteriorate, resulting in lithium precipitation, which will reduce the life of the battery cell and poor reliability.

[0101] Based on the above considerations, in order to solve the problem of poor reliability of the winding structure of the core in the battery cell, the utility model author designed a battery cell, including: a shell, an electrode assembly and a buffer, the electrode assembly is arranged in the shell, and includes an isolation membrane and a pole piece, the isolation membrane and the pole piece are stacked and wound, and a central space is formed in the center of the electrode assembly; the buffer includes a buffer part and an extension part, the buffer part is arranged in the central space, the extension part is located outside the central space, and is arranged between the shell and the electrode assembly.

[0102] In a battery cell of this structure, a buffer is provided including a buffer portion and an extension portion. The buffer portion is provided in the central space formed by the winding of the isolation membrane and the pole piece and plays a buffering role. Thus, the innermost pole piece can be supported during the hot pressing of the winding core structure formed by the isolation membrane and the pole piece, thereby reducing the probability of brittle fracture during the hot pressing of the winding structure and the probability of burrs, which is beneficial to improving the reliability of the electrode assembly and thus improving the reliability of the battery cell. Under the support of the buffer portion, the distance between the pole pieces at the innermost corner of the electrode assembly can also be reduced, and the probability of a large gap between the pole pieces at the innermost corner of the electrode assembly can be reduced, thereby reducing the probability of lithium deposition. By providing the extension portion between the outer shell and the electrode assembly, the extension portion separates the electrode assembly from the outer shell, reducing the possibility of collision between the electrode assembly and the outer shell when assembled into the outer shell, and reducing the probability of damage to the electrode assembly, thereby improving the reliability of the battery cell.

[0103] The battery disclosed in the embodiment of the present application can be used in, but not limited to, electrical devices such as vehicles, ships or aircraft. A power supply system comprising the battery cell system and batteries disclosed in the present application can be used to form the electrical device, which is beneficial to improve the application range of the battery cell.

[0104] The embodiment of the present application provides an electric device using a battery as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, 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., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0105] 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.

[0106] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may 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 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0107] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0108] Please refer to Figure 2 , Figure 2The structural exploded diagram of the battery 100 provided for some embodiments of the present application. The battery 100 includes a box body 10 and a plurality of battery cells 20, and the battery cells 20 are used to be accommodated in the box body 10. Among them, the box body 10 is used to provide an assembly space for the battery cells 20, and the box body 10 can adopt a variety of structures. In some embodiments, the box body 10 may include a first box body 11 and a second box body 12, and the first box body 11 and the second box body 12 cover each other, and the first box body 11 and the second box body 12 jointly define an assembly space for accommodating the battery cells 20. The second box body 12 can be a hollow structure with one end open, and the first box body 11 can be a plate-like structure. The first box body 11 covers the open side of the second box body 12, so that the first box body 11 and the second box body 12 jointly define the assembly space; the first box body 11 and the second box body 12 can also be hollow structures with one side open, and the open side of the first box body 11 covers the open side of the second box body 12. Of course, the box body 10 formed by the first box body 11 and the second box body 12 can be in various shapes, such as a cylinder, a cuboid, etc.

[0109] In the battery 100, multiple battery cells 20 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection means that multiple battery cells 20 are connected in series and in parallel. Multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid connection, and then the whole formed by multiple battery cells 20 is accommodated in the box 10; of course, the battery 100 can also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection, and then multiple battery modules are connected in series, in parallel, or in a hybrid connection to form a whole, and accommodated in the box 10. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between multiple battery cells 20.

[0110] Please refer to Figure 2 , Figure 2 A partial structural diagram of a battery 100 provided in some embodiments of the present application. The battery 100 includes multiple rows of battery cells 20, which are arranged along the length direction of the box 10, and each row of battery cells 20 includes multiple battery cells 20 arranged along the width direction of the box 10; or, multiple rows of battery cells 20 are arranged along the width direction of the box 10, and each row of battery cells 20 includes multiple battery cells 20 arranged along the length direction of the box 10.

[0111] Each battery cell 20 may be a secondary battery or a primary battery; it 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. Figure 2 In the figure, the battery cell 20 is in the shape of a rectangular parallelepiped.

[0112] According to some embodiments of the present application, in the first aspect, referring to Figure 3 , Figure 4 and Figure 5 The embodiment of the present application provides a battery cell 20 , including: a housing 21 , an electrode assembly 22 and a buffer 23 .

[0113] The electrode assembly 22 is disposed in the housing 21 and includes a separator 221 and a pole piece 222. The separator 221 and the pole piece 222 are stacked and wound, and a central space 22a is formed at the center of the electrode assembly 22. The buffer 23 includes a buffer portion 231 and an extension portion 232. The buffer portion 231 is disposed in the central space 22a, and the extension portion 232 is located outside the central space 22a and is disposed between the housing 21 and the electrode assembly 22.

[0114] The shell 21 may refer to the external protective structure of the battery cell 20, which is used to wrap and protect the chemical substances and electrode assembly 22 inside the battery cell 20. The shell 21 may be, but not limited to, a circular shell, a square shell, etc. The shell 21 may be, but not limited to, made of one of aluminum, steel, and stainless steel.

[0115] The separator 221 and the pole piece 222 are wound so that the electrode assembly 22 forms a winding core structure, and the central space 22a may refer to the central gap of the winding core structure. The central space 22a may be, but is not limited to, a cylindrical gap, a flat-plate gap, and the like. For example, when the winding core structure is cylindrical, the central space 22a may be a cylindrical gap; when the winding core structure is a flat winding structure, the central space 22a may be a flat-plate gap.

[0116] The electrode assembly 22 may include a pole piece 222. It can be understood that, in this embodiment, the battery cell 20 may not be provided with a negative electrode material, for example, there is no negative electrode sheet, and the pole piece 222 in this embodiment is a positive electrode sheet, and the positive electrode sheet and the separator 221 are stacked and wound to form a winding core structure. In this example, when the battery cell 20 is working, the metal in the positive electrode sheet can migrate to the surface of the negative electrode current collector, thereby forming a metal layer on the negative electrode current collector to become the negative electrode.

[0117] The electrode assembly 22 may also include a plurality of electrode sheets 222. It can be understood that, in this embodiment, the plurality of electrode sheets 222 may include a positive electrode sheet and a negative electrode sheet, the separator 221 is disposed between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the separator 221 and the negative electrode sheet are stacked and wound to form a winding core structure. The number of positive electrode sheets and negative electrode sheets may be, but is not limited to, two, three, four, and the like.

[0118] The buffer portion 231 may refer to a material or structure. The buffer portion 231 has an elastic function, can shrink under pressure, and return to its original shape after the external force is removed, so as to absorb or reduce impact force, vibration and pressure, thereby protecting the components of surrounding devices. The buffer portion 231 may be made of, but not limited to, one or more of a rubber material, a foam material and a polyurethane material. The buffer portion 231 may be, but not limited to, a cylindrical shape, a flat plate shape, etc. Figure 4 , exemplarily, the central space 22a may be a flat plate-shaped gap, and the buffer portion 231 may be a flat plate-shaped gap.

[0119] The buffer portion 231 may be one or more. When there is one buffer portion 231, the buffer portion 231 may have a larger size. For example, the buffer portion 231 is a buffer plate, and only one buffer plate is needed to fill the space of the central space 22a, or fill most of the space of the central space 22a. When there are multiple buffer portions 231, the buffer portion 231 may be a long strip of buffer strips, and the multiple buffer strips may be spaced apart along the length direction of the central space 22a (the length direction of the central space 22a may refer to Figure 4 third direction Z).

[0120] The extension portion 232 may refer to a portion of the structure extending out of the central space 22a in the buffer 23. The extension portion 232 and the buffer portion 231 may have the same or different structures. The extension portion 232 can separate the electrode assembly 22 from the housing 21, reduce the probability of hard contact between the electrode assembly 22 and the housing 21, reduce the probability of collision when the electrode assembly 22 enters the housing, and improve the reliability of the electrode assembly 22. Moreover, when the extension portion 232 and the buffer portion 231 have the same structure, the extension portion 232 can also have a buffering effect, which can further reduce the probability of collision between the electrode assembly 22 and the housing 21 and improve the reliability of the electrode assembly 22.

[0121] The extension portion 232 may be in the shape of, but not limited to, a circular sheet, a rectangular sheet, a strip sheet, etc. Optionally, there may be one extension portion 232, in which case the extension portion 232 may have a larger size, and one extension portion 232 may support most or all of the end surfaces of the electrode assembly 22. There may also be multiple extension portions 232, in which case the extension portions 232 may be in the shape of long strips and arranged in rows in sequence. Figure 5 Exemplarily, the extension portion 232 is in the shape of a rectangular sheet, and is one and is disposed between the corresponding electrode assembly 22 and the housing 21 , and the extension portion 232 and the buffer portion 231 form a T-shaped structure.

[0122] It should be noted that in the above solution, the battery cell 20 may include a plurality of electrode assemblies 22, and each electrode assembly 22 is provided with a corresponding buffer 23. Figure 3The battery cell 20 includes two electrode assemblies 22 , and each electrode assembly 22 is provided with a buffer 23 .

[0123] In the battery cell 20 of the present application, the buffer portion 231 is arranged in the central space 22a, thereby balancing the expansion force generated by the expansion of the battery cell 20 during the charging and discharging process, increasing the inner circle curvature of the winding core structure, and reducing the probability of brittle fracture of the inner circle pole piece 222. At the same time, the buffer portion 231 can also support the innermost circle pole piece 222, reducing the probability of a large gap between two adjacent pole pieces 222 in the innermost circle, thereby reducing the probability of lithium precipitation, which is beneficial to extending the service life of the battery cell 20 and improving the reliability of the battery cell 20. The extension portion 232 is arranged between the electrode assembly 22 and the outer shell 21, which can reduce the probability of direct contact between the electrode assembly 22 and the outer shell 21, reduce the probability of coating damage caused by direct contact between the electrode assembly 22 and the outer shell 21, and improve the reliability of the electrode assembly 22.

[0124] In the above technical solution, the buffer 23 includes a buffer portion 231 and an extension portion 232. The buffer portion 231 is arranged in the central space 22a formed by the separation membrane 221 and the pole piece 222 and plays a buffering role, thereby supporting the innermost pole piece 222 during the hot pressing of the winding core structure formed by the separation membrane 221 and the pole piece 222, reducing the probability of brittle fracture during hot pressing of the winding structure and reducing the probability of burrs. Moreover, under the support of the buffer portion 231, the pole piece spacing at the innermost corner of the electrode assembly 22 can be reduced, and the probability of a large gap between the pole pieces 222 at the innermost corner of the electrode assembly 22 is reduced, thereby reducing the probability of lithium deposition, thereby improving the reliability of the electrode assembly 22, and further improving the reliability of the battery cell 20. By arranging the extension portion 232 between the outer shell 21 and the electrode assembly 22, the extension portion 232 separates the electrode assembly 22 and the outer shell 21, thereby reducing the probability of the electrode assembly 22 colliding with the outer shell 21 when assembled into the outer shell 21, and reducing the probability of damage to the electrode assembly 22, thereby further improving the reliability of the battery cell 20.

[0125] In some embodiments of the present application, reference Figure 6 The extension portion 232 includes a heat conductive base 2321 , which is connected to the buffer portion 231 and is disposed in close contact with the housing 21 .

[0126] The heat-conducting substrate 2321 may refer to the main body of the extension portion 232 and has a heat-conducting function. The heat-conducting substrate 2321 may be, but is not limited to, a heat-conducting metal plate, a graphene plate, a heat-conducting silicone sheet, and the like.

[0127] Since the buffer part 231 is arranged in the central space 22a of the electrode assembly 22, the contact surface between the buffer part 231 and the electrode piece 222 is relatively large. Since the heat generated inside the electrode assembly 22 is relatively large, the heat generated by the electrode assembly 22 is mostly concentrated on the large surface and the top, so the buffer part 231 can transfer the heat of the electrode assembly 22 to the heat conductive matrix 2321, and the heat conductive matrix 2321 then transfers the heat to the shell 21, and then the heat of the shell 21 is taken away by the external cooling device, which is beneficial to improve the heat dissipation efficiency of the battery cell 20. The external cooling device can be understood as a device for temperature control of the battery cell 20. Here, the cooling device can be but not limited to a water cooling device, etc.

[0128] In the above technical solution, by configuring the extension portion 232 to include a heat-conducting substrate 2321, the extension portion 232 can also have a heat-conducting effect and can increase the heat exchange surface area between the electrode assembly 22 and the outer shell 21, thereby allowing the heat inside the electrode assembly 22 to be quickly transferred to the outer shell 21, thereby improving the heat dissipation efficiency, being beneficial to the cooling of the battery cell 20, and effectively reducing the temperature rise of the battery cell 20, reducing the side reactions inside the battery, being beneficial to slowing down the battery capacity attenuation, and improving the reliability and performance of the battery cell 20.

[0129] In some embodiments of the present application, reference Figure 6 The extension portion 232 also includes an insulating portion 2322 , which is disposed on a side of the heat conductive substrate 2321 close to the electrode assembly 22 and is attached to the electrode assembly 22 .

[0130] The insulating part 2322 may refer to a component with insulating properties, and specifically may refer to a non-conductive material or coating that can be used to prevent current from passing through. When the insulating part 2322 is a non-conductive material, the insulating part 2322 may be made of, but not limited to, at least one of polyethylene, polypropylene, polyvinyl chloride, and paper tape. When the insulating part 2322 is a coating, the insulating part 2322 may be, but not limited to, an aluminum oxide coating, a titanium oxide coating, and the like.

[0131] The insulating portion 2322 may be, but is not limited to, an insulating sheet, an insulating film, an insulating coating, and the like. Wherein, when the insulating portion 2322 is an insulating sheet, the insulating portion 2322 and the heat-conducting substrate 2321 may both be sheet-like structures, whereby the insulating portion 2322 and the heat-conducting substrate 2321 are constructed as a double-layer structure, and the insulating sheet and the heat-conducting substrate 2321 may be connected in a manner that is, but is not limited to, bonding, clamping, and the like. When the insulating portion 2322 is an insulating film, the insulating film covers the heat-conducting substrate 2321, and the insulating film and the heat-conducting substrate 2321 may be connected in a manner that is, but is not limited to, bonding, and the like. When the insulating portion 2322 is an insulating coating, the insulating coating is directly coated on the heat-conducting substrate 2321.

[0132] In the above technical solution, by setting the extension portion 232 to also include an insulating portion 2322, the extension portion 232 can also have an insulating effect, thereby reducing the probability of electrical connection between the electrode assembly 22 and the outer shell 21, and also reducing the probability of short circuit between the electrode assembly 22 and the outer shell 21, thereby improving the reliability of the battery cell 20.

[0133] In some embodiments of the present application, an insulating portion 2322 is provided on one side of the heat-conducting substrate 2321 close to the electrode assembly 22 and on the circumferential side surface arranged along the winding direction of the pole piece 222. That is to say, the insulating portion 2322 can be arranged not only on the large end surface of the heat-conducting substrate 2321 close to the electrode assembly 22, but also on the circumferential side surface of the heat-conducting substrate 2321. At this time, only one side of the heat-conducting substrate 2321 is exposed and in contact with the outer shell 21. In this way, the insulating portion 2322 can have a better insulating effect on the heat-conducting substrate 2321, improve the insulation between the heat-conducting substrate 2321 and the electrode assembly 22, further reduce the probability of contact between the electrode assembly 22 and the outer shell 21, and thus further improve the reliability of the battery cell 20.

[0134] In some embodiments of the present application, the thermal conductivity of the thermally conductive substrate 2321 may be greater than or equal to 50 W / (m·K).

[0135] It can be understood that the thermal conductivity of the thermally conductive substrate 2321 can be but is not limited to 50W / (m·K), 55W / (m·K), 60W / (m·K), 65W / (m·K), 70W / (m·K), 75W / (m·K), 80W / (m·K), 90W / (m·K), 100W / (m·K), 110W / (m·K), 120W / (m·K), 150W / (m·K), 200W / (m·K), and the like.

[0136] In the above technical solution, by setting the thermal conductivity of the heat-conductive substrate 2321 to be greater than or equal to 50W / (m·K), the heat-conductive substrate 2321 can have a higher thermal conductivity efficiency, so that the heat of the electrode assembly 22 can be transferred to the outer shell 21 more quickly, which is beneficial to the rapid cooling of the battery cell 20 and further improves the reliability of the battery cell 20.

[0137] In some embodiments of the present application, reference Figure 6 A protrusion 2323 is provided at one end of the insulating portion 2322 close to the buffer portion 231 , and the protrusion 2323 is arranged around the circumference of the buffer portion 231 .

[0138] The protrusion 2323 may refer to a protruding structure of the insulating portion 2322. For example, taking the isolation film 221 and the pole piece 222 winding around the first direction X as an example, the protrusion 2323 may refer to an annular structure arranged around the buffer portion 231 around the first direction X.

[0139] refer to Figure 3 and Figure 6 When the isolation film 221 and the pole piece 222 are wound around the first direction X to form a core structure, the pole piece 222 is prone to folding or damage at the end of the first direction X. When the thermal conductive substrate 2321 is made of a conductive material, a connection area is formed between the thermal conductive substrate 2321 and the buffer portion 231. The folded or damaged position of the pole piece 222 is prone to contact with the connection area, thereby easily causing a short circuit problem.

[0140] In the above technical solution, by providing the insulating part 2322 with a protrusion 2323, the protrusion 2323 can play an insulating protection role in the connection area between the heat-conducting substrate 2321 and the buffer part 231, thereby reducing the probability of the connection area between the heat-conducting substrate 2321 and the buffer part 231 being exposed, thereby reducing the probability of a short circuit caused by contact with the connection area of ​​the heat-conducting substrate 2321 when the end of the pole piece 222 is folded or damaged, thereby improving the reliability of the battery cell 20.

[0141] In some embodiments of the present application, reference Figure 6 The protruding height of the protruding portion 2323 is H1, wherein 0mm≤H1≤5mm.

[0142] It can be understood that the height H1 of the protrusion 2323 can be, but is not limited to, 0 mm, 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5 mm, etc. If the height H1 of the protrusion 2323 is greater than 5 mm, the protrusion height of the protrusion 2323 will be relatively large, which will affect the winding of the innermost pole piece 222 and make the protrusion 2323 too long, resulting in material waste.

[0143] In the above technical solution, by setting the protrusion height H1 of the protrusion 2323 within the range of 0mm to 5mm, the protrusion 2323 can have an appropriate height, which can effectively separate the end area of ​​the pole piece 222 from the connection area between the thermal conductive substrate 2321 and the buffer portion 231, thereby having a better insulation protection effect, and can also reduce the manufacturing cost of the protrusion 2323.

[0144] In some embodiments of the present application, reference Figure 6 , the thickness of the insulating portion 2322 is T1, where 0.1 mm ≤ T1 ≤ 1 mm.

[0145] It can be understood that the thickness T1 of the insulating portion 2322 can be but is not limited to 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc.

[0146] If the thickness T1 of the insulating part 2322 is less than 0.1 mm, the insulating effect of the insulating part 2322 is poor, the probability of being broken down by the current is relatively high, and the risk of short circuit between the electrode assembly 22 and the thermal conductive substrate 2321 is also relatively high; if the thickness T1 of the insulating part 2322 is greater than 1 mm, the thickness of the insulating part 2322 will be larger and will occupy a larger space, which is not conducive to increasing the volume share of the electrode assembly 22 and will affect the improvement of the volume energy density of the battery cell 20.

[0147] In the above technical solution, by setting the thickness T1 of the insulating part 2322 within the range of 0.1mm to 1mm, the thickness T1 of the insulating part 2322 is within an appropriate range. While having a good insulation effect, the thickness of the insulating part 2322 can be not too thick. On the one hand, it can reduce costs, and on the other hand, it is beneficial to reduce the overall thickness of the extension part 232 and increase the volume share of the electrode assembly 22, which is beneficial to increase the volume energy density of the battery cell 20.

[0148] In some embodiments of the present application, reference Figure 6 The thickness of the thermal conductive substrate 2321 is T2, wherein 0.1 mm ≤ T2 ≤ 1 mm.

[0149] It can be understood that the thickness T2 of the thermally conductive substrate 2321 can be but is not limited to 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc.

[0150] In the above technical solution, by setting the thickness T2 of the thermally conductive substrate 2321 within the range of 0.1 mm to 1 mm, the thickness T2 of the thermally conductive substrate 2321 is within an appropriate range. While having better support and thermal conductivity effects, the thickness of the thermally conductive substrate 2321 can be made not too thick. On the one hand, it can reduce costs, and on the other hand, it is beneficial to improve the energy density of the battery cell 20.

[0151] In some embodiments of the present application, the extension portion 232 and the buffer portion 231 are separate structures, and the extension portion 232 and the buffer portion 231 are connected by bonding or thermal bonding.

[0152] The extension portion 232 and the buffer portion 231 may have different structures. The buffer portion 231 can play a buffering role in the central space 22a, and is used to balance the expansion force of the electrode piece 222. The extension portion 232 may have other functions. For example, the extension portion 232 may have a heat-conducting effect, and quickly transfer the heat of the electrode assembly 22 to the outer shell 21; or, the extension portion 232 may have an insulating effect, and is used to separate the electrode assembly 22 and the outer shell 21, and reduce the probability of short circuit caused by electrical connection between the electrode assembly 22 and the outer shell 21. Alternatively, the extension portion 232 may have both heat-conducting and insulating effects. It can be seen that the split structure of the extension portion 232 and the buffer portion 231 is conducive to expanding the function of the extension portion 232.

[0153] In the above examples, the extension portion 232 and the buffer portion 231 may be connected by bonding, or the extension portion 232 and the buffer portion 231 may be connected by thermal bonding.

[0154] In the above technical solution, by setting the extension part 232 and the buffer part 231 as a separate structure, it is beneficial for the extension part 232 to adopt a structure different from the buffer part 231 and have a function different from the buffer part 231, which is beneficial to expand the function of the buffer 23. On the other hand, the extension part 232 and the buffer part 231 can also be of the same structure, but because the extension part 232 and the buffer part 231 are separate structures, the extension part 232 and the buffer part 231 can be manufactured separately, which can reduce the difficulty of manufacturing the buffer 23 and help reduce the manufacturing cost.

[0155] In some embodiments of the present application, the extension portion 232 and the buffer portion 231 are integrally formed. Exemplarily, the buffer member 23 is in a T-shaped structure as a whole.

[0156] In the above technical solution, by setting the extension part 232 and the buffer part 231 as an integrally formed part, the structure of the buffer part 23 is more stable, and the probability of separation between the extension part 232 and the buffer part 231 is relatively low, which facilitates the assembly of the extension part 232 and the buffer part 231 to the electrode assembly 22, and also facilitates the assembly of the buffer part 23 and the electrode assembly 22 into the housing 21, which can improve the assembly efficiency of the battery cell 20. In addition, since the extension part 232 and the buffer part 231 are integrally formed parts, the extension part 232 is not easy to be displaced in the housing 21, which can improve the reliability of the extension part 232 in the housing 21, and further help improve the reliability of the battery cell 20.

[0157] In some embodiments of the present application, reference Figure 3 The isolation film 221 and the pole piece 222 are wound around the first direction X, a pole ear 223 is provided at one end of the pole piece 222 along the first direction X, and the extension portion 232 is provided on a side of the electrode assembly 22 away from the pole ear 223 .

[0158] In this embodiment, the first direction X may be one of the length direction, width direction, and height direction of the battery cell 20. Figure 3 The first direction X is the height direction of the battery cell 20 .

[0159] In the above technical solution, since the extension 232 and the pole ear 223 are located at both ends of the electrode assembly 22, the probability of mutual influence between the extension 232 and the pole ear 223 is relatively low, which facilitates bending of the pole ear 223 at one end of the pole piece 222, and also facilitates the connection between the pole ear 223 and the pole 24. Moreover, the extension 232 will not be affected by the pole piece 222, so on the one hand, it is convenient to arrange the extension 232, and on the other hand, the size of the extension 232 can be set relatively large, which can better support the electrode assembly 22.

[0160] In some embodiments of the present application, reference Figure 3 The electrode tab 223 is located at the top of the electrode assembly 22 , and the extension portion 232 is located at the bottom of the electrode assembly 22 and supported by the housing 21 .

[0161] In the above technical solution, the extension part 232 can play the role of a bottom support plate, supporting the electrode assembly 22 in the housing 21, and has a "one thing for two purposes" function, so that there is no need to set up a bottom support plate, which can reduce costs and reduce the bottom support plate into the shell process, which is conducive to improving assembly efficiency. Since the buffer part 231 is located in the central space 22a of the electrode assembly 22, and the extension part 232 is connected to the buffer part 231, the position of the extension part 232 and the electrode assembly 22 is relatively fixed, which can reduce the sliding friction between the electrode assembly 22 and the extension part 232, thereby reducing the probability of wear of the pole piece 222, and improving the reliability of the electrode assembly 22.

[0162] In some embodiments of the present application, reference Figure 5 A shell wall of the shell 21 close to the extension portion 232 is provided with a rounded corner 21 a , the radius of the rounded corner 21 a is R, and the thickness of the extension portion 232 is T3 , wherein 1 / 3R≤T3≤R.

[0163] T3 may be, but is not limited to, 1 / 3R, 3 / 6R, 4 / 6R, 5 / 6R, R, etc. If T3 is less than 1 / 3R, the thickness of the extension 232 is relatively small. Since the outer shell 21 has a rounded corner 21a, after the electrode assembly 22 is inserted into the shell, the extension 232 has a relatively small lifting height for the electrode assembly 22. The edge of the electrode assembly 22 is more likely to contact the rounded corner 21a, which may easily cause damage to the electrode assembly 22, resulting in coating damage or short circuit. If T3 is greater than R, the thickness of the extension 232 will be relatively large. Although the extension 232 has a relatively large lifting height for the electrode assembly 22, which can effectively reduce the probability of collision between the edge of the electrode assembly 22 and the rounded corner 21a, it will cause the extension 232 to occupy a relatively large volume in the outer shell 21, and the volume of the electrode assembly 22 will decrease, which is not conducive to improving the volume energy density of the battery cell 20.

[0164] In the above technical solution, by setting the relationship between the thickness T3 of the extension portion 232 and the radius R of the fillet 21a of the outer shell 21 within the above range, the extension portion 232 can have a more suitable thickness. On the one hand, the electrode assembly 22 can be lifted to a suitable height, reducing the probability of contact between the electrode assembly 22 and the fillet 21a of the outer shell 21, thereby reducing damage to the electrode assembly 22 and improving the reliability of the electrode assembly 22. On the other hand, it can also help to reduce the volume share of the extension portion 232 in the outer shell 21, which can improve the volume energy density of the battery cell 20.

[0165] In some embodiments of the present application, reference Figure 8 and Fig. 9 The isolation film 221 and the pole piece 222 are wound around the first direction X, and a pole ear 223 is provided at one end of the pole piece 222 along the first direction X, and the extension portion 232 is provided on a side of the electrode assembly 22 close to the pole ear 223 .

[0166] The pole piece 222 is wound around the first direction X to form a multi-turn structure, and each turn of the pole piece 222 is bent to form a pole ear 223, and then the multiple pole ears 223 are gathered to form a larger pole ear group, which is electrically connected to the pole column 24. When the pole ear of the pole piece in the related art is folded, the pole ear may be electrically connected to the adjacent pole piece to cause a short circuit (for example, the pole ear of the positive pole piece contacts the negative pole piece when being bent to cause a short circuit).

[0167] In the above technical solution, the extension portion 232 is arranged on the side of the electrode assembly 22 close to the pole ear 223, that is, the extension portion 232 and the pole ear 223 are located on the same side of the electrode assembly 22, so that the extension portion 232 can block the central space 22a and the end surface of the pole piece 222, thereby reducing the probability of the pole ear 223 being inserted into the central space 22a or contacting the pole piece 222 to cause a short circuit when the pole ear 223 is folded, thereby improving the reliability of the electrode assembly 22, thereby improving the reliability of the battery cell 20.

[0168] In some embodiments of the present application, reference Fig.10 The isolation film 221 and the pole piece 222 are wound around the first direction X, a pole ear 223 is provided at one end of the pole piece 222 along the first direction X, and an extension portion 232 is provided at both ends of the electrode assembly 22 located in the first direction X.

[0169] It can be understood that the buffer 23 is in an I-shaped structure, and the two ends of the buffer portion 231 are connected to the extension portions 232. The structures of the extension portions 232 at the two ends of the electrode assembly 22 in the first direction X can be the same or different.

[0170] Exemplarily, the extension portions 232 located at both ends of the first direction X of the electrode assembly 22 can both play an insulating role, that is, the extension portion 232 includes an insulating portion 2322. Among the extension portions 232 located at both ends of the first direction X of the electrode assembly 22, one can play an insulating role between the pole ear 223 and the pole piece 222, and the other can play an insulating role between the electrode assembly 22 and the outer shell 21.

[0171] Exemplarily, the extension portions 232 located at both ends of the first direction X of the electrode assembly 22 can both play a blocking and heat-conducting role, that is, the extension portion 232 includes a thermally conductive substrate 2321 and an insulating portion 2322, so that the extension portion 232 can not only play an insulating role, but also transfer the heat of the electrode assembly 22 to the outer shell 21, and because the extension portion 232 can transfer heat to the outer shell 21 at both ends of the first direction X of the electrode assembly 22, the thermal conductivity efficiency is higher and the heat dissipation effect is better.

[0172] For example, one of the extensions 232 at both ends of the electrode assembly 22 in the first direction X can serve as an insulator and the other can serve as a buffer. As for the buffering effect, the structure of the extension 232 and the structure of the buffer 231 can be the same, thereby reducing the probability of the electrode assembly 22 colliding with the outer shell 21 when entering the shell.

[0173] In the above technical solution, among the extension portions 232 located at both ends of the first direction X of the electrode assembly 22, the one located on the same side of the electrode assembly 22 as the pole ear 223 can play a role in blocking the pole ear 223 and the pole piece 222, thereby reducing the probability of short circuit caused by electrical connection between the pole ear 223 and the pole piece 222, while the other one located on a different side of the electrode assembly 22 from the pole ear 223 can play a buffering and isolating role between the electrode assembly 22 and the outer shell 21, thereby reducing the probability of damage to the pole piece 222 caused by direct contact between the electrode assembly 22 and the outer shell 21.

[0174] In some embodiments of the present application, the isolation film 221 and the pole piece 222 are wound around the first direction X, the pole piece 222 is provided with pole ears 223 at both ends along the first direction X, and the electrode assembly 22 is provided with extension parts 232 at both ends in the first direction X.

[0175] In this embodiment, the buffer member 23 is in an I-shaped structure, and both ends of the buffer portion 231 are connected to the extending portions 232 .

[0176] In the above technical solution, pole ears 223 are provided at both ends of the electrode assembly 22, and extension portions 232 are provided at both ends of the buffer portion 231, and are provided corresponding to the pole ears 223 at both ends of the electrode assembly 22. This can reduce the probability of short circuit between the pole ears 223 and the pole pieces 222 at both ends of the electrode assembly 22 in the first direction X, thereby improving the reliability of the battery cell 20.

[0177] In some embodiments of the present application, on a plane perpendicular to the first direction X, a projection of one end of the pole ear 223 away from the pole piece 222 on the plane is located within a projection of the extension portion 232 on the plane.

[0178] In the above technical solution, it can be understood that the size of the extension portion 232 is relatively large, and it can also be understood that the area of ​​the extension portion 232 away from the surface of the electrode assembly 22 is relatively large. In this way, when the electrode piece 222 is folded at the electrode ear 223, the end of the electrode ear 223 away from the electrode piece 222 is more easily blocked by the extension portion 232, and the electrode ear 223 is not easy to cross the extension portion 232 and contact other electrode pieces 222, thereby further reducing the probability of the electrode ear 223 and the electrode piece 222 being electrically connected and causing a short circuit.

[0179] In some embodiments of the present application, reference Fig.10 and Fig.11 The electrode ear 223 is located on one side of the extension portion 232 in the third direction Z. The electrode assembly 22 has a second direction Y perpendicular to the third direction Z. In the second direction Y, the width of the electrode assembly 22 is D1, the width of the extension portion 232 is D2, and the thickness of the buffer portion 231 is T6, wherein T6<D2≤1 / 2D1.

[0180] In the above technical solution, the width of the extension portion 232 is at least greater than the thickness of the buffer portion 231, so that the extension portion 232 can block the central space 22a, reducing the probability of the tab 223 being inserted into the central space 22a. By setting the width of the extension portion 232 to be less than or equal to one-half of the width of the electrode assembly 22, the width of the extension portion 232 can be prevented from being too long, reducing the influence of the extension portion 232 on the tab 223.

[0181] In some embodiments of the present application, reference Fig.11The electrode assembly 22 has a first surface 22b close to the extension portion 232, and the extension portion 232 has a second surface 232a close to the first surface 22b. The distance between the second surface 232a and the first surface 22b is H2, wherein 1mm≤H2≤3mm.

[0182] H2 can be, but is not limited to, 1 mm, 1.2 mm, 1.4 mm, 1.5 mm, 1.7 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.5 mm, 2.7 mm, 3.0 mm, and the like.

[0183] Since the winding core structure formed by winding the pole piece 222 is a multi-layer structure, and the pole lug 223 is folded on each pole piece 222, and the multiple pole lugs 223 are gathered to form a pole lug group, the pole lug group has a certain thickness near the root of the pole piece 222. If the distance H2 between the second surface 232a and the first surface 22b is less than 1mm, the space between the second surface 232a and the first surface 22b is not enough to accommodate the root of the pole lug group, which is not conducive to the arrangement of the pole lug 223; if the distance H2 between the second surface 232a and the first surface 22b is greater than 3mm, the space between the second surface 232a and the first surface 22b will be relatively large, which is easy to cause space waste, and accordingly, the position of the extension part 232 relative to the electrode assembly 22 is relatively high, the volume of the extension part 232 is relatively large, and the space occupied is relatively large, which will affect the volume proportion of the electrode assembly 22 in the shell 21 and the volume energy density of the battery cell 20.

[0184] In the above technical solution, by setting the distance between the first surface 22b of the electrode assembly 22 close to the extension portion 232 and the second surface 232a of the extension portion 232 close to the first surface 22b to 1mm~3mm, a suitable space can be provided between the first surface 22b and the second surface 232a of the extension portion 232. On the one hand, it can provide a suitable space to accommodate the root of the pole ear 223 close to the pole piece 222, and on the other hand, it is beneficial to reduce the height of the extension portion 232 relative to the electrode assembly 22, thereby reducing the volume of the extension portion 232, and further reducing the volume share of the extension portion 232 in the outer shell 21, which is beneficial for the electrode assembly 22 to have a larger volume share in the outer shell 21, thereby improving the volume energy density of the battery cell 20.

[0185] In some embodiments of the present application, reference Fig.12 and Fig.13 The electrode assembly 22 has multiple side surfaces, at least one of which is a first side surface 22c, the area of ​​the first side surface 22c is greater than the areas of the other side surfaces, and the extension portion 232 is provided with a first extension portion 233 extending to the first side surface 22c, and the first extension portion 233 covers the first side surface 22c.

[0186] “Side” may refer to a surface surrounding the outer peripheral contour of the electrode assembly 22. For example, when the first direction X is the height direction of the electrode assembly 22, the multiple side surfaces may refer to surfaces arranged around the first direction X. Exemplarily, when the electrode assembly 22 is a rectangular parallelepiped, the multiple side surfaces may refer to the left side surface, the right side surface, the front side surface, and the rear side surface of the electrode assembly 22. Among them, the first side surface 22c may refer to the surface with the largest area among the multiple side surfaces.

[0187] The first extension part 233 may refer to a structure extending from the extension part 232, and the structure of the first extension part 233 may be the same as or different from the structure of the extension part 232. Exemplarily, the first extension part 233 may have an insulating function, in this example, the first extension part 233 may include an insulating portion 2322; the first extension part 233 may also have a heat conducting function, in this example, the first extension part 233 may include a heat conducting base 2321; the first extension part 233 may also have an insulating function and a heat conducting function, in this example, the first extension part 233 may include an insulating portion 2322 and a heat conducting base 2321.

[0188] It can be understood that after the electrode assembly 22 is inserted into the shell, the electrode assembly 22 always interacts with the outer shell 21 on a large surface to remain relatively fixed, that is, a pressing force is formed between the first side surface 22c of the electrode assembly 22 and the outer shell 21, and the first extension portion 233 covers the first side surface 22c, which can separate the electrode assembly 22 and the outer shell 21, thereby reducing the probability of electrical connection between the electrode assembly 22 and the outer shell 21, thereby reducing the probability of corrosion of the outer shell 21.

[0189] When there are multiple electrode assemblies 22, except for the two ends of the multiple electrode assemblies 22 that will be pressed against the outer shell 21, any two adjacent electrode assemblies 22 will also be pressed against each other through the first side surface 22c. Therefore, the first extension portion 233 covers the first side surface 22c, and can also separate the two adjacent electrode assemblies 22 from each other, reduce the probability of damage caused by contact between the electrode assemblies 22, and can insulate the two adjacent electrode assemblies 22.

[0190] In the above technical solution, the first extension part 233 can replace the insulating sheet to play an insulating role, separate the electrode assembly 22 from the surrounding components, play a good insulating role for the electrode assembly 22, and reduce the probability of damage caused by contact between the electrode assembly 22 and the surrounding components, which can improve the reliability of the electrode assembly 22 and the reliability of the battery cell 20. In addition, the first extension part 233 can also reduce the use of insulating sheets in the battery cell 20, which can reduce costs. At the same time, the first extension part 233 can maintain a relatively fixed position with the electrode assembly 22, thereby facilitating the insertion of the electrode assembly 22 into the shell, which is conducive to improving the assembly efficiency of the battery cell 20.

[0191] In some embodiments of the present application, reference Fig.12 and Fig.13 The extension portion 232 is further provided with a second extension portion 234 , which is connected to the first extension portion 233 and is located on a side of the electrode assembly 22 close to the pole ear 223 .

[0192] The second extension portion 234 may refer to a portion extending from the first extension portion 233, and the structures of the second extension portion 234 and the first extension portion 233 may be the same or different. The structure formed by the second extension portion 234, the first extension portion 233 and the extension portion 232 may be a T-shaped structure.

[0193] In the above technical solution, the second extension portion 234 can act as a separator between adjacent electrode assemblies 22, thereby reducing the probability of the electrode ear 223 being inserted into the adjacent electrode assembly 22 when the electrode ear 223 is folded, thereby reducing the probability of electrical connection and causing a short circuit, thereby improving the reliability of the electrode assembly 22 and thus improving the reliability of the battery cell 20.

[0194] In some embodiments of the present application, reference Fig.12 and Fig.13 The electrode ear 223 is located on one side of the second extension portion 234 in the third direction Z. The electrode assembly 22 has a second direction Y perpendicular to the third direction Z. In the second direction Y, the width of the electrode assembly 22 is D1, and the width of the second extension portion 234 is D3, wherein D1≤D3≤3 / 2D1.

[0195] D3 may be, but is not limited to, D1, 5 / 4D1, 8 / 6D1, 3 / 2D1, etc. If D3 is smaller than D1, the width of the second extension portion 234 is relatively small, and it cannot effectively prevent the tab 223 from being inserted inwardly; if D3 is larger than 3 / 2D1, the width of the second extension portion 234 is relatively large, and thus the size of the second extension portion 234 is redundant, and occupies a relatively large space, which will affect the volume energy density of the battery cell 20, and will also pull the welding mark of the tab 223, affecting the connection reliability of the tab 223 and the pole 24, thereby affecting the reliability of the battery cell 20.

[0196] In the above technical solution, by setting the width D1 of the electrode assembly 22 and the width D3 of the second extension part 234 within the above range, the second extension part 234 can have a suitable width range. On the one hand, the second extension part 234 can have a larger size to block the tab 223, reducing the probability of the tab 223 being inserted into the adjacent electrode assembly 22 when bent, thereby reducing the probability of the electrode assembly 22 short-circuiting, and will not affect the welding of the tab 223 and the pole 24, which is beneficial to improve the reliability of the battery cell 20. On the other hand, the volume of the second extension part 234 in the housing 21 will not be too large, which is beneficial to make the electrode assembly 22 have a larger volume in the housing 21, which is beneficial to improve the volume energy density of the battery cell 20.

[0197] In some embodiments of the present application, reference Figure 4 , both ends of the buffer portion 231 extend to the corners of the pole piece 222 .

[0198] The “corner of the pole piece 222” may refer to the bending area of ​​the pole piece 222 at both ends of the third direction Z and located in the central space 22a. By extending both ends of the buffer portion 231 to the corner of the pole piece 222, the buffer portion 231 can support the corner of the innermost pole piece 222, further reducing the gap between the two innermost pole pieces 222, so that the difference between the distance between the two innermost pole pieces 222 and the distance between the two outermost pole pieces 222 is relatively small.

[0199] For example, reference Figure 4 The buffer portion 231 is located in the central space 22a, and can support the two corners of the innermost pole piece 222 in the third direction Z, and can also support the two large surfaces of the innermost pole piece 222 in the second direction Y. Therefore, the distance between the two innermost pole pieces 222 is relatively small, and the difference between the distance between the two outermost pole pieces 222 is not much different, so lithium plating is not likely to occur.

[0200] In the above technical solution, by extending the two ends of the buffer portion 231 to the corners of the pole piece 222, the buffer portion 231 can provide better support for the innermost pole piece 222, which is beneficial to further reduce the distance between the two pole pieces 222 at the innermost corner of the electrode assembly 22, and can further reduce the probability of lithium plating.

[0201] In some embodiments of the present application, reference Figure 6 The buffer portion 231 includes an elastic portion 2311 and a heat conducting portion 2312 , and the heat conducting portion 2312 is disposed on at least one side of the elastic portion 2311 close to the pole piece 222 .

[0202] The elastic part 2311 may refer to a structure or material that has elasticity, can shrink under pressure and recover after the external force is removed. The elastic part 2311 may be made of, but not limited to, one or more materials selected from EPS (expanded polystyrene), EPP (expanded polypropylene), and EPE (expanded polyethylene).

[0203] The heat conducting part 2312 may refer to a material or component that can transfer heat. The heat conducting part 2312 may be, but not limited to, a heat conducting layer, a heat conducting film, a heat conducting sheet, and the like. The heat conducting part 2312 may be, but not limited to, made of silicon carbide material and heat conducting metal material. For example, when the heat conducting part 2312 is a heat conducting layer, the heat conducting layer may be replaced with a silicon carbide layer, a metal foil layer, and the like. The metal foil layer may be, but not limited to, a copper foil layer or an aluminum foil layer, and the like.

[0204] The heat conducting portion 2312 may be provided in a plurality on the side of the elastic portion 2311, and the plurality of heat conducting portions 2312 may be arranged at intervals. For example, the heat conducting portion 2312 may be a heat conducting strip, and the plurality of heat conducting strips may be arranged along the third direction Z (see Figure 4 ) interval settings.

[0205] The heat conducting portion 2312 may cover the side of the elastic portion 2311 close to the pole piece 222. In other words, the heat conducting portion 2312 may be a heat conducting sheet, and may completely cover the side close to the pole piece 222.

[0206] The heat conducting part 2312 is arranged on at least one side of the elastic part 2311 close to the pole piece 222. It can be understood that the elastic part 2311 has multiple sides close to the pole piece 222, and the heat conducting part 2312 can be arranged on including but not limited to one side, two sides, three sides, four sides, etc.

[0207] For example, reference Figure 4 The elastic part 2311 has four side surfaces close to the pole piece 222, including two large surfaces located at both ends of the second direction Y, and two small surfaces located at both ends of the third direction Z. The heat conductive part 2312 can be arranged on the two large surfaces of the elastic part 2311 located at both ends of the second direction Y.

[0208] For another example, when the size of the central space 22a in the second direction Y is larger, the heat conducting portion 2312 can be arranged not only on the side surfaces at both ends of the elastic portion 2311 along the second direction Y, but also on the side surfaces at both ends of the elastic portion 2311 along the third direction Z.

[0209] It can be understood that since the heat conductive portion 2312 can contact the innermost pole piece 222 and the heat generated by the electrode assembly 22 is mostly concentrated inside, the heat inside the electrode assembly 22 can be quickly discharged through the heat conductive portion 2312, and the heat conductive portion 2312 can transfer the heat to the outer shell 21 through the extension portion 232, thereby improving the heat dissipation efficiency of the battery cell 20.

[0210] Optionally, refer to Figure 6 The extension part 232 may include a heat-conducting substrate 2321, which is connected to the buffer part 231 and is attached to the housing 21, and the heat-conducting part 2312 is connected to the heat-conducting substrate 2321. Thus, the heat-conducting part 2312 can quickly transfer the heat inside the electrode assembly 22 to the heat-conducting substrate 2321, and transfer it to the housing 21 through the heat-conducting substrate 2321, and then the heat of the battery cell 20 is quickly taken away by the external cooling device. With this solution, the buffer part 231 and the extension part 232 have a high heat conductivity, which can further improve the heat dissipation efficiency of the battery cell 20, and can effectively reduce the temperature rise of the battery cell 20, further reduce the internal side reactions of the battery, and help to further improve the reliability of the battery cell 20.

[0211] In the above technical solution, by configuring the buffer portion 231 to include an elastic portion 2311 and a heat-conducting portion 2312, the buffer portion 231 can not only play a buffering role through the elastic portion 2311 to balance the expansion force generated by the electrode assembly 22, but also play a heat-conducting role through the heat-conducting portion 2312, which is beneficial to quickly dissipate the heat inside the electrode assembly 22, and is beneficial to improving the heat dissipation efficiency of the battery cell 20, thereby improving the reliability of the battery cell 20.

[0212] In some embodiments of the present application, the thermal conductivity of the heat-conducting portion 2312 may be greater than or equal to 50 W / (m·K).

[0213] It can be understood that the thermal conductivity of the heat-conducting part 2312 can be but is not limited to 50W / (m·K), 55W / (m·K), 60W / (m·K), 65W / (m·K), 70W / (m·K), 75W / (m·K), 80W / (m·K), 90W / (m·K), 100W / (m·K), 110W / (m·K), 120W / (m·K), 150W / (m·K), 200W / (m·K), and the like.

[0214] In the above technical solution, by setting the thermal conductivity of the heat-conducting part 2312 to be greater than or equal to 50W / (m·K), the heat-conducting part 2312 can have a higher thermal conductivity efficiency, so that the heat of the electrode assembly 22 can be transferred to the outer shell 21 more quickly, which is beneficial to the rapid cooling of the battery cell 20 and further improves the reliability of the battery cell 20.

[0215] In some embodiments of the present application, the heat conducting portion 2312 is a heat conducting layer covering the surface of the elastic portion 2311. It can be understood that when the heat conducting portion 2312 is disposed on a certain surface of the elastic portion 2311, the area of ​​the heat conducting portion 2312 is equal to that of the surface, that is, the heat conducting portion 2312 can completely cover the surface of the elastic portion 2311.

[0216] In the above technical solution, by setting the heat-conducting part 2312 as a heat-conducting layer covering the surface of the elastic part 2311, the contact area between the heat-conducting part 2312 and the elastic part 2311 and the pole piece 222 can be as large as possible, thereby enabling a larger heat exchange surface area between the heat-conducting part 2312 and the pole piece 222, and the heat transfer efficiency of the heat-conducting part 2312 is higher, so that the heat of the electrode assembly 22 can be transferred to the outer shell 21 more quickly, further improving the heat dissipation efficiency of the battery cell 20, thereby improving the reliability of the battery cell 20.

[0217] In some embodiments of the present application, the isolation film 221 and the pole piece 222 are wound around the first direction X. In the first direction X, the height of the electrode assembly 22 is H3, and the height of the elastic portion 2311 is H4, wherein -3 mm ≤ H4 - H3 ≤ 3 mm.

[0218] It can be understood that H4-H3 can be but is not limited to -3mm, -2.5mm, -2.0mm, -1.5mm, -1.0mm, -0.5mm, 0mm, 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, etc.

[0219] If H4-H3 is less than -3mm, the size of the elastic part 2311 is more than 3mm smaller than the size of the electrode assembly 22, and there are many parts of the electrode assembly 22 that are not supported by the elastic part 2311, which is easy to cause stress concentration at the end of the electrode assembly 22, greatly increasing the probability of fracture and burrs at the end of the electrode assembly 22, seriously affecting the reliability of the electrode assembly 22. If H4-H3 is greater than 3mm, the size of the elastic part 2311 is more than 3mm larger than the size of the electrode assembly 22. At this time, the part of the elastic part 2311 extending out of the electrode assembly 22 is relatively long. Since the outer shell 21 is provided with a pole 24, the pole piece 222 has a pole ear 223, and the pole ear 223 is connected to the pole 24 (refer to Figure 3 ), the elastic portion 2311 is longer and will easily affect the arrangement of the tab 223 , occupying more space and affecting the energy density of the battery cell 20 .

[0220] In the above technical solution, by setting the difference between the height H4 of the elastic part 2311 and the height H3 of the electrode assembly 22 within the range of -3mm to 3mm, the elastic part 2311 can have a larger support range for the innermost pole piece 222 of the electrode assembly 22, reducing the probability of stress concentration in the innermost pole piece 222 of the electrode assembly 22, and at the same time reducing the probability of the elastic part 2311 extending too long from the electrode assembly 22 and affecting the battery energy density. Secondly, the above solution can also make the elastic part 2311 have a suitable processing tolerance range, which is conducive to the processing and manufacturing of the elastic part 2311, can reduce the manufacturing difficulty of the elastic part 2311, and improve the product yield.

[0221] In some embodiments of the present application, reference Figure 7 The elastic portion 2311 has a third surface 2311a at one end away from the extension portion 232, and the heat conducting portion 2312 has a fourth surface 2312a at one end away from the extension portion 232. In the first direction X, a height difference between the third surface 2311a and the fourth surface 2312a is H5, where 0mm≤H5≤5mm.

[0222] It can be understood that H5 can be but is not limited to 0mm, 0.5mm, 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm, 4.0mm, 4.5mm, 5mm, etc.

[0223] If H5 is less than 0 mm, the height of the elastic portion 2311 is less than the height of the heat conducting portion 2312, and the portion of the heat conducting portion 2312 that is more than the elastic portion 2311 lacks support, which is not conducive to molding. Secondly, the extra portion of the heat conducting portion 2312 will affect the tab 223 and occupy a larger space in the housing 21, thereby affecting the energy density of the battery cell 20.

[0224] If H5 is greater than 5 mm, the height of the heat-conducting part 2312 is much smaller than the height of the elastic part 2311 , which may easily lead to a large gap between the elastic part 2311 and the innermost pole piece 222 , thereby causing stress concentration on the electrode assembly 22 , affecting the reliability of the electrode assembly 22 , and thus affecting the reliability of the battery cell 20 .

[0225] In the above technical scheme, by setting the difference between the third surface 2311a of the elastic part 2311 and the fourth surface 2312a of the heat conductive part 2312 within the range of 0mm to 5mm, the effect of the heat conductive part 2312 exceeding the elastic part 2311 on the pole ear 223 can be reduced, as well as the larger space occupied in the outer shell 21, which affects the energy density of the battery cell 20. At the same time, the probability of a large gap between the elastic part 2311 and the innermost pole piece 222 can be reduced, thereby reducing the probability of stress concentration in the electrode assembly 22, thereby improving the reliability of the battery cell 20.

[0226] In some embodiments of the present application, reference Figure 7 , the thickness of the elastic portion 2311 is T4, wherein 0.5 mm ≤ T4 ≤ 3 mm.

[0227] The thickness T4 of the elastic portion 2311 may be, but is not limited to, 0.5 mm, 0.7 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3.0 mm, and the like.

[0228] If the thickness T4 of the elastic part 2311 is less than 0.5 mm, the strength of the elastic part 2311 is relatively small, the support for the innermost pole piece 222 is poor, the effect of reducing the probability of brittle fracture of the innermost pole piece 222 is not good, and the effect of reducing the distance between the two innermost pole pieces 222 is not good. If the thickness T4 of the elastic part 2311 is greater than 3 mm, although the elastic part 2311 has better support, its thickness increases, it will occupy a larger space, affecting the energy density of the battery cell 20.

[0229] In the above technical solution, by setting the thickness T4 of the elastic part 2311 within the range of 0.5mm to 3mm, the elastic part 2311 occupies a relatively small space while ensuring support. In other words, the elastic part 2311 can have a relatively high strength, which can better support the pole piece 222 of the innermost circle of the electrode assembly 22. At the same time, the thickness of the elastic part 2311 can also be more appropriate, which is beneficial to improving the energy density of the battery cell 20.

[0230] In some embodiments of the present application, reference Figure 7 , the thickness of the heat conducting portion 2312 is T5, wherein 10 μm≤T5≤500 μm.

[0231] The thickness T5 of the heat conductive portion 2312 may be, but is not limited to, 10 μm, 20 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, 320 μm, 340 μm, 360 μm, 380 μm, 400 μm, 420 μm, 440 μm, 460 μm, 500 μm, and the like. If the thickness T5 of the heat-conducting part 2312 is less than 10 μm, the thickness of the heat-conducting part 2312 is relatively small, the heat-conducting effect is poor, and the heat transfer rate of the electrode assembly 22 cannot be effectively improved; if the thickness T5 of the heat-conducting part 2312 is greater than 500 μm, the thickness of the heat-conducting part 2312 and the elastic part 2311 is relatively large, which will occupy a larger space and affect the energy density of the battery cell 20.

[0232] In the above technical solution, by setting the thickness T5 of the heat-conducting part 2312 within the range of 10μm to 500μm, the thickness of the heat-conducting part 2312 is within an appropriate range, and the heat-conducting part 2312 occupies a relatively small space while ensuring thermal conductivity. In other words, the heat-conducting part 2312 can have a relatively good thermal conductivity effect, and at the same time, the thickness of the heat-conducting part 2312 and the elastic part 2311 is relatively appropriate, which is beneficial to improving the energy density of the battery cell 20.

[0233] According to the battery cell 20 provided in the embodiment of the present application, a T-shaped buffer structure is arranged in the outer shell 21, and the T-shaped buffer structure includes a buffer pad and a thermal conductive pad. The buffer pad is arranged in the central space 22a of the core structure, and the thermal conductive pad is in contact with the bottom of the core structure. The surface of the buffer pad is coated with a thermal conductive coating, and the thermal conductive pad includes a bottom thermal conductive layer and an insulating layer covering the bottom thermal conductive layer. The bottom thermal conductive layer is connected to the thermal conductive coating and is in contact with the bottom shell wall of the outer shell 21. The insulating layer is arranged at one end of the bottom thermal conductive layer close to the core structure, and the insulating layer has a protrusion 2323 extending to the buffer pad.

[0234] In a second aspect, the embodiment of the present application further provides a battery 100 , comprising the battery cell 20 described above.

[0235] In the above technical solution, since the battery cell 20 has high reliability, the battery 100 having the battery cell 20 can also have high reliability, which can reduce the probability of failure of the battery 100 during use and improve the performance of the battery 100.

[0236] In a third aspect, the embodiment of the present application further provides an electric device, including the battery cell 20 or battery 100 mentioned above. In the above technical solution, since the battery cell 20 and the battery 100 have high reliability, the electric device having the battery cell 20 or the battery 100 can also have high power reliability, which can reduce the probability of power failure of the electric device during use and improve the performance of the electric device.

[0237] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The above are only preferred embodiments of this application and are not intended to limit this application. For those skilled in the art, this application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should be included in the protection scope of this application.

Claims

1. A battery cell, characterized in that: include: shell; An electrode assembly, the electrode assembly is arranged in the housing and comprises a separator and a pole piece, the separator and the pole piece are stacked and wound, and a central space is formed at the central position of the electrode assembly; The buffer member comprises a buffer portion and an extension portion, wherein the buffer portion is arranged in the central space, and the extension portion is located outside the central space and arranged between the housing and the electrode assembly.

2. The battery cell according to claim 1, characterized in that: The extension portion includes a heat-conducting base, which is connected to the buffer portion and is attached to the housing.

3. The battery cell according to claim 2, characterized in that: The extension portion further includes an insulating portion, which is disposed on a side of the heat conductive substrate close to the electrode assembly and adheres to the electrode assembly.

4. The battery cell according to claim 3, characterized in that: A protrusion is provided at one end of the insulating portion close to the buffer portion, and the protrusion is arranged around the circumference of the buffer portion.

5. The battery cell according to claim 4, characterized in that: The protruding height of the protruding portion is H1, wherein 0mm≤H1≤5mm.

6. The battery cell according to claim 3, characterized in that: The thickness of the insulating portion is T1, wherein 0.1 mm≤T1≤1 mm.

7. The battery cell according to any one of claims 2 to 6, characterized in that: The thickness of the thermally conductive substrate is T2, wherein 0.1 mm≤T2≤1 mm.

8. The battery cell according to any one of claims 2 to 6, characterized in that: The extension part and the buffer part are separate structures, and the extension part and the buffer part are connected by bonding or thermal compounding.

9. The battery cell according to claim 1, characterized in that: The extending portion and the buffer portion are an integrally formed part.

10. The battery cell according to claim 1, characterized in that: The isolation film and the pole piece are wound in a first direction, a pole ear is provided at one end of the pole piece along the first direction, and the extension portion is provided on a side of the electrode assembly away from the pole ear.

11. The battery cell according to claim 10, characterized in that: The electrode tab is located at the top of the electrode assembly, and the extension portion is located at the bottom of the electrode assembly and supported by the housing.

12. The battery cell according to claim 11, characterized in that: A shell wall of the shell close to the extension portion is provided with a rounded corner, the radius of the rounded corner is R, and the thickness of the extension portion is T3, wherein 1 / 3R≤T3≤R.

13. The battery cell according to claim 1, characterized in that: The isolation film and the pole piece are wound in a first direction, a pole ear is provided at one end of the pole piece along the first direction, and the extension portion is provided on a side of the electrode assembly close to the pole ear.

14. The battery cell according to claim 1, characterized in that: The isolation film and the pole piece are wound in a first direction, a pole ear is provided at one end of the pole piece along the first direction, and the extension portions are provided at both ends of the electrode assembly located in the first direction.

15. The battery cell according to claim 1, characterized in that: The isolation film and the pole piece are wound in a first direction, pole ears are provided at two ends of the pole piece along the first direction, and the extension parts are provided at two ends of the electrode assembly located in the first direction.

16. The battery cell according to any one of claims 10 to 15, characterized in that: On a plane perpendicular to the first direction, a projection of an end of the pole ear away from the pole piece on the plane is located within a projection of the extension portion on the plane.

17. The battery cell according to any one of claims 10 to 15, characterized in that: The electrode ear is located on one side of the extension portion in the third direction, and the electrode assembly has a second direction perpendicular to the third direction. In the second direction, the width of the electrode assembly is D1, the width of the extension portion is D2, and the thickness of the buffer portion is T6, wherein T6<D2≤1 / 2D1.

18. The battery cell according to any one of claims 10 to 15, characterized in that: The electrode assembly has a first surface close to the extension portion, and the extension portion has a second surface close to the first surface. The distance between the second surface and the first surface is H2, wherein 1 mm≤H2≤3 mm.

19. The battery cell according to any one of claims 10 to 15, characterized in that: The electrode assembly has multiple side surfaces, at least one of which is a first side surface, the area of ​​the first side surface is larger than the areas of the other side surfaces, and the extension portion is provided with a first extension portion extending to the first side surface, and the first extension portion covers the first side surface.

20. The battery cell according to claim 19, characterized in that: The extension portion is further provided with a second extension portion, which is connected to the first extension portion and is located on a side of the electrode assembly close to the electrode ear.

21. The battery cell according to claim 20, characterized in that: The electrode ear is located on one side of the second extension portion in the third direction, and the electrode assembly has a second direction perpendicular to the third direction. In the second direction, the width of the electrode assembly is D1, and the width of the second extension portion is D3, wherein D1≤D3≤3 / 2D1.

22. The battery cell according to claim 1, characterized in that: Both ends of the buffer portion extend to the corners of the pole piece.

23. The battery cell according to claim 22, characterized in that: The buffer portion includes an elastic portion and a heat-conducting portion, wherein the heat-conducting portion is arranged on at least one side of the elastic portion close to the pole piece.

24. The battery cell according to claim 23, characterized in that: The heat-conducting portion is a heat-conducting layer covering the surface of the elastic portion.

25. The battery cell according to claim 23 or 24, characterized in that: The isolation film and the pole piece are wound in a first direction. In the first direction, the height of the electrode assembly is H3, and the height of the elastic portion is H4, wherein -3mm≤H4-H3≤3mm.

26. The battery cell according to claim 25, characterized in that: The elastic portion has a third surface at one end away from the extension portion, and the heat conductive portion has a fourth surface at one end away from the extension portion. In the first direction, a height difference between the third surface and the fourth surface is H5, wherein 0mm≤H5≤5mm.

27. The battery cell according to claim 23 or 24, characterized in that: The thickness of the elastic portion is T4, wherein 0.5 mm ≤ T4 ≤ 3 mm.

28. The battery cell according to claim 23 or 24, characterized in that: The thickness of the heat conducting portion is T5, wherein 10 μm≤T5≤500 μm.

29. A battery, characterized in that: The invention comprises a battery cell as claimed in any one of claims 1 to 28.

30. An electrical device, characterized in that: Comprising the battery cell according to any one of claims 1 to 28, or the battery according to claim 29.

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