Battery cell, battery and electric device

Abstract

A battery cell (20), comprising: a casing (21); an electrode assembly (22), wherein the electrode assembly (22) is arranged in the casing (21) and comprises a separator (221) and electrode sheets (222), the separator (221) and the electrode sheets (222) being stacked and wound, and a central space (22a) being formed at the center of the electrode assembly (22); and a buffer member (23), which comprises a buffer portion (231) and an extension portion (232), the buffer portion (231) being arranged in the central space (22a), and the extension portion (232) being located outside the central space (22a) and arranged between the casing (21) and the electrode assembly (22). By means of the configuration of the buffer member (23) comprising the buffer portion (231) and the extension portion (232), the probability of brittle fracture during hot pressing of a winding structure is reduced, and the probability of bur formation is thus reduced; in addition, the spacing between the electrode sheets at the innermost corner of the electrode assembly (22) is reduced, the probability of a large gap occurring between the electrode sheets (222) at the innermost corner of the electrode assembly (22) is reduced, and the probability of lithium plating is reduced. By using the extension portion (232) to separate the electrode assembly (22) from the casing (21), the probability of the electrode assembly (22) colliding with the casing (21) when assembled into the casing (21) is reduced, thereby improving the reliability of the battery cell (20).

Description

Battery cells, batteries and electrical devices 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] New energy vehicles have experienced rapid growth in recent years. Within the electric vehicle sector, power batteries, as the power source, play an irreplaceable and important role. A battery consists of a housing and multiple cells housed within it. As a core component of new energy vehicles, batteries have high safety and service life requirements. However, core-wound battery cells often exhibit reliability issues, severely impacting the reliability of the cells.

[0003] Summary of the Invention

[0004] 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.

[0005] In a first aspect, an embodiment of the present application provides a battery cell, comprising: a shell; an electrode assembly, the electrode assembly being disposed in the shell and comprising an isolation membrane and a pole piece, the isolation membrane and the pole piece being stacked and wound, and forming a central space at the center of the electrode assembly; a buffer member, comprising a buffer portion and an extension portion, the buffer portion being disposed in the central space, the extension portion being located outside the central space, and disposed between the shell and the electrode assembly.

[0006] In the above technical solution, a buffer member including a buffer portion and an extension portion is provided. The buffer portion is provided in the central space formed by the winding of the separator and the electrode sheet and acts as a buffer. This can support the innermost electrode sheet during the hot pressing of the core structure formed by the separator and the electrode sheet, thereby reducing the probability of brittle fracture during the hot pressing of the winding structure and the probability of burrs. Moreover, under the support of the buffer portion, the distance between the electrode sheets at the innermost corner of the electrode assembly can be reduced, reducing the probability of large gaps between the electrode sheets at the innermost corner of the electrode assembly, thereby reducing the probability of lithium plating, thereby improving the reliability of the electrode assembly and further improving the reliability of the battery cell. By providing the extension portion between the outer shell and the electrode assembly, the extension portion separates the electrode assembly and the outer shell, reducing the probability of collision between the electrode assembly and the outer shell when assembled into the outer shell, reducing the probability of damage to the electrode assembly, thereby further improving the reliability of the battery cell.

[0007] In some embodiments of the present application, the extension portion includes: a heat-conducting base, the heat-conducting base is connected to the buffer portion, and is fitted to the housing.

[0008] In the above technical solution, by setting the extension part to include a heat-conducting substrate, the extension part can also have a heat-conducting function and can increase the heat exchange surface area between the electrode assembly and the shell, thereby quickly transferring the heat inside the electrode assembly to the 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, and being beneficial to slowing down the battery capacity attenuation, which can improve the reliability and performance of the battery cell.

[0009] In some embodiments of the present application, the extension portion further includes: an insulating portion, which is provided on a side of the heat-conductive base close to the electrode assembly and is attached to the electrode assembly.

[0010] 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.

[0011] 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.

[0012] 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 a short circuit caused by contact with the connection area of ​​the heat-conducting substrate when the end of the electrode is folded or damaged, thereby improving the reliability of the battery cell.

[0013] In some embodiments of the present application, the protruding height of the protrusion is H1, where 0mm≤H1≤5mm.

[0014] In the above technical solution, by setting the protruding height H1 of the protrusion to be 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-conducting substrate and the buffer part, thereby providing better insulation protection, and at the same time reduce the manufacturing cost of the protrusion.

[0015] In some embodiments of the present application, the thickness of the insulating portion is T1, where 0.1 mm ≤ T1 ≤ 1 mm.

[0016] 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 also be made 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 and increase the volume share of the electrode assembly, which is beneficial to increase the volume energy density of the battery cell.

[0017] In some embodiments of the present application, the thickness of the thermally conductive substrate is T2, where 0.1 mm ≤ T2 ≤ 1 mm.

[0018] In the above technical solution, by setting the thickness T2 of the thermally conductive base 2321 within the range of 0.1 mm to 1 mm, the thickness T2 of the thermally conductive base 2321 is within an appropriate range. While having good support and thermal conductivity effects, the thickness of the thermally conductive base 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.

[0019] 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.

[0020] In the above technical solution, by providing the extension portion and the buffer portion as separate structures, the extension portion can advantageously adopt a different structure and function from the buffer portion, thereby expanding the function of the buffer. Alternatively, the extension portion and the buffer portion can have the same structure, but because they are separate structures, they can be manufactured separately, which can reduce the difficulty of manufacturing the buffer and help reduce manufacturing costs.

[0021] In some embodiments of the present application, the extension portion and the buffer portion are an integrally formed part.

[0022] In the above technical solution, by providing the extension portion and the buffer portion as an integrally molded component, the buffer portion structure is more stable, the probability of separation between the extension portion and the buffer portion is relatively low, and the extension portion and the buffer portion are easily assembled to the electrode assembly. It is also convenient to assemble the buffer portion and the electrode assembly together into the housing, which can improve the assembly efficiency of the battery cell. Moreover, because the extension portion and the buffer portion are integrally molded, the extension portion is less likely to move within the housing, which can improve the reliability of the extension portion within the housing, thereby improving the reliability of the battery cell.

[0023] 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 the extension portion is provided on a side of the electrode assembly away from the pole ear.

[0024] In the above technical solution, since the extension and the tab are located at both ends of the electrode assembly, the probability of mutual interference between the extension and the tab is relatively low, making it easier to bend the tab out of one end of the electrode piece and to connect the tab to the electrode column. Furthermore, the extension is not affected by the electrode piece, which not only facilitates the placement of the extension, but also allows for a larger extension to better support the electrode assembly.

[0025] In some embodiments of the present application, the tab is located at the top of the electrode assembly, and the extension is located at the bottom of the electrode assembly and supported by the housing.

[0026] In the above technical solution, the extension can serve as a base plate, supporting the electrode assembly within the housing, achieving a dual purpose. This eliminates the need for a base plate, reducing costs and simplifying the process of inserting the base plate into the housing, thereby improving assembly efficiency. Because the buffer portion is located within the central space of the electrode assembly and the extension portion is connected to the buffer portion, the position of the extension portion and the electrode assembly is relatively fixed, reducing sliding friction between the electrode assembly and the extension portion, thereby reducing the chance of electrode wear and improving the reliability of the electrode assembly.

[0027] In some embodiments of the present application, a shell wall on a 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.

[0028] 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 shell within the above range, the extension part can have a more appropriate thickness. On the one hand, it can lift the electrode assembly to a suitable height, reduce the probability of contact between the electrode assembly and the rounded corner of the shell, thereby reducing damage to the electrode assembly and improving the reliability of the electrode assembly. On the other hand, it can also help reduce the volume share of the extension part in the shell, which can increase the volume energy density of the battery cell.

[0029] 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 the extension portion is provided on a side of the electrode assembly close to the pole ear.

[0030] 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.

[0031] 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.

[0032] In the above technical solution, among the extensions at both ends of the first direction of the electrode assembly, the one located on the same side of the electrode assembly as the tab can serve to block the tab and the electrode sheet, thereby reducing the probability of short circuit caused by electrical connection between the tab and the electrode sheet, while the other one located on a different side of the electrode assembly from the tab can serve as a buffer barrier between the electrode assembly and the outer shell, thereby reducing the probability of damage to the electrode sheet caused by direct contact between the electrode assembly and the outer shell.

[0033] In some embodiments of the present application, the isolation membrane and the pole piece are wound in 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.

[0034] In the above technical solution, tabs are provided at both ends of the electrode assembly, and extensions are provided at both ends of the buffer portion, which are arranged corresponding to the tabs at both ends of the electrode assembly. This can reduce the probability of short circuit in the electrical connection between the tabs and the pole pieces at both ends of the electrode assembly in the first direction, and can improve the reliability of the battery cell.

[0035] In some embodiments of the present application, on a plane perpendicular to the first direction, a projection of an end of the tab away from the pole piece on the plane is located within a projection of the extension on the plane.

[0036] In the above technical solution, it can be understood that the size of the extension is relatively large, or it can be understood that the area of ​​the extension away from the surface of the electrode assembly is relatively large. In this way, when the electrode is folded, the end of the electrode away from the electrode is more easily blocked by the extension, and the electrode is not easy to cross the extension and contact other electrode sheets, thereby further reducing the probability of electrical connection between the electrode and the electrode causing a short circuit.

[0037] 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.

[0038] In the above technical solution, the width of the extension is at least greater than the thickness of the buffer portion. This allows the extension to block the central space, reducing the chance of the tab being inserted into the central space. By setting the width of the extension to be less than or equal to half the width of the electrode assembly, the extension is kept from being excessively long, minimizing its impact on the tab.

[0039] 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.

[0040] In the above technical solution, by setting the distance between the first surface of the electrode assembly close to the extension part and the second surface of the extension part 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, it can provide a suitable space 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 part relative to the electrode assembly, thereby reducing the volume of the extension part, and then reducing the volume share of the extension part 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.

[0041] 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.

[0042] In the above technical solution, the first extension can replace the insulating sheet to provide insulation, separating the electrode assembly from surrounding components. This provides better insulation for the electrode assembly and reduces the chance of damage from contact between the electrode assembly and surrounding components, thereby improving the reliability of the electrode assembly and the battery cell. Furthermore, the first extension can reduce the use of insulating sheets in the battery cell, reducing costs. Furthermore, the first extension can remain relatively fixed relative to the electrode assembly, facilitating the insertion of the electrode assembly into the battery case and improving battery cell assembly efficiency.

[0043] In some embodiments of the present application, 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 tab.

[0044] In the above technical solution, the second extension portion can act as a separator between adjacent electrode assemblies, reducing the probability of the electrode tab being inserted into the adjacent electrode assembly when folding the electrode tab, causing electrical connection and short circuit, thereby improving the reliability of the electrode assembly and thus improving the reliability of the battery cell.

[0045] In some embodiments of the present application, the electrode tab 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.

[0046] In the above technical solution, by setting the electrode assembly width D1 and the second extension width D3 within the above range, the second extension has an appropriate width range. On the one hand, the second extension has a larger size to separate the tabs, reducing the chance of the tabs inserting into adjacent electrode assemblies when bent, thereby reducing the chance of short circuits in the electrode assemblies and not affecting the welding of the tabs and posts, thereby improving the reliability of the battery cells. On the other hand, the second extension can be made to occupy a smaller volume within the housing, thereby facilitating a larger volumetric share of the electrode assembly within the housing and improving the volumetric energy density of the battery cells.

[0047] In some embodiments of the present application, both ends of the buffer portion extend to the corners of the pole piece.

[0048] In the above technical solution, by extending the two ends of the buffer portion to the corners of the pole pieces, the buffer portion can provide better support for the innermost pole pieces, 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.

[0049] 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.

[0050] In the above technical solution, by setting the buffer part to include an elastic part and a heat-conducting part, the buffer part can not only play a buffering role through the elastic part to balance the expansion force generated by the electrode assembly, but also play a heat-conducting role through the heat-conducting part, 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.

[0051] In some embodiments of the present application, the heat-conducting portion is a heat-conducting layer covering the surface of the elastic portion.

[0052] 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 surface between the heat-conducting part and 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.

[0053] In some embodiments of the present application, the isolation membrane 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.

[0054] In the above technical solution, by setting the difference between the height H4 of the elastic portion and the height H3 of the electrode assembly within a range of -3mm to 3mm, the elastic portion can provide a wider range of support for the innermost electrode sheet of the electrode assembly, reducing the probability of stress concentration in the innermost electrode sheet of the electrode assembly. It also reduces the probability of the elastic portion extending too far beyond the electrode assembly and affecting the battery's energy density. Furthermore, the above solution can also ensure that the elastic portion has an appropriate processing tolerance range, facilitating its processing and manufacturing, reducing the manufacturing difficulty of the elastic portion, and improving product yield.

[0055] 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.

[0056] In the above technical solution, 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 extra elastic part of the heat-conducting part on the pole ear and the large space occupied in the outer shell, which affects the energy density of the battery cell, can be reduced. At the same time, the probability of a large gap between the elastic part and the innermost circle of the pole piece can also be reduced, thereby reducing the probability of stress concentration in the electrode assembly and improving the reliability of the battery cell.

[0057] In some embodiments of the present application, the thickness of the elastic portion is T4, wherein 0.5 mm ≤ T4 ≤ 3 mm.

[0058] 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. That is to say, the elastic part can have a relatively high strength and provide better support for the pole piece of the innermost circle 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.

[0059] In some embodiments of the present application, the thickness of the heat conducting portion is T5, wherein 10 μm≤T5≤500 μm.

[0060] In the above technical solution, by setting the thickness T5 of the heat-conducting part within the range of 10μm to 500μm, the thickness of the heat-conducting part is within an appropriate range. The heat-conducting part occupies a relatively small space while ensuring thermal conductivity. In other words, the heat-conducting part can have a relatively good heat-conducting 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.

[0061] In a second aspect, an embodiment of the present application further provides a battery, comprising the battery cell described above.

[0062] 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.

[0063] In a third aspect, an embodiment of the present application further provides an electrical device comprising the aforementioned battery cell or battery.

[0064] 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 in the electrical devices during use and improve the performance of the electrical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

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

[0067] FIG2 is an exploded view of the structure of a battery provided in some embodiments of the present application;

[0068] FIG3 is a schematic diagram of the internal structure of a battery cell provided in some embodiments of the present application;

[0069] FIG4 is a schematic diagram of the assembly of an electrode assembly and a buffer portion according to some embodiments of the present application;

[0070] FIG5 is a schematic diagram of a partial structure of a battery cell provided in some embodiments of the present application;

[0071] FIG6 is a schematic structural diagram of a buffer provided in some embodiments of the present application;

[0072] FIG7 is a partial enlarged schematic diagram of point I in FIG6;

[0073] FIG8 is a schematic diagram of a three-dimensional structure of an electrode assembly and a buffer component after assembly according to some embodiments of the present application;

[0074] FIG9 is a side view 1 of an assembled electrode assembly and a buffer member according to some embodiments of the present application;

[0075] FIG10 is a second side view of an assembled electrode assembly and a buffer member according to some embodiments of the present application;

[0076] FIG11 is a partial enlarged schematic diagram of point II in FIG10;

[0077] FIG12 is a second schematic diagram of the three-dimensional structure of the electrode assembly and the buffer component after assembly according to some embodiments of the present application;

[0078] FIG13 is a third side view of the assembled electrode assembly and buffer component according to some embodiments of the present application.

[0079] Icons: 1000, vehicle; 100, battery; 10, housing; 11, first housing body; 12, second housing body; 20, battery cell; 21, housing; 21a, fillet; 22, electrode assembly; 221, separator; 222, pole piece; 223, pole tab; 22a, central space; 22b, first surface; 22c, first side surface; 223, pole tab; 23, buffer; 231, buffer portion; 2311, elastic portion; 2311a, third surface; 2312, heat-conducting portion; 2312a, fourth surface; 232, extension portion; 232a, second surface; 2321, heat-conducting base; 2322, insulating portion; 2323, protrusion; 233, first extension portion; 234, second extension portion; 24, pole; 200, controller; 300, motor; X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0080] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0081] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0082] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0083] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0084] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0085] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0086] The term "plurality" used in this application refers to two or more (including two).

[0087] In this 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 this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0088] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or battery pack. A battery generally includes a casing that encloses one or more battery cells or multiple battery modules. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0089] A battery cell consists of a casing, an electrode assembly, and an electrolyte. The casing is used to hold the electrode assembly and electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet comprises a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive electrode collector. The uncoated positive electrode collector protrudes from the coated positive electrode collector, and the uncoated positive electrode collector serves as the positive electrode tab. For lithium-ion batteries, for example, the positive electrode current collector can be made of aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet comprises a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative electrode collector. The uncoated negative electrode collector protrudes from the coated negative electrode collector, and the uncoated negative electrode collector serves as the negative electrode tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon, etc. In order to ensure that a large current can pass without melting, the positive electrode tabs are multiple and stacked together, and the negative electrode tabs are multiple and stacked together.

[0090] The material of the isolation film may be PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly may be a wound structure or a laminated structure, but the embodiments of the present application are not limited thereto.

[0091] New energy vehicles have experienced rapid growth in recent years. Within the electric vehicle sector, power batteries, as the power source, play an irreplaceable and important role. A battery consists of a housing and multiple cells housed within it. As a core component in new energy vehicles, batteries have high requirements for both safety and cycle life.

[0092] In typical wound-core battery cells, the separator separates the positive and negative electrodes, which are then hot-pressed after being wound into a core. The innermost negative electrode has a smaller radius of curvature (almost folded in half), causing the positive and negative electrodes to break easily. Furthermore, due to the high density and high coating quality of the negative electrode, it is more susceptible to brittle fracture than the positive electrode. Burrs and powder loss after brittle fracture can easily cause a short circuit within the battery, reducing the reliability of the battery cell. Furthermore, since the inner ring of electrodes has no support after winding and needle extraction, the inner ring tends to become loose, increasing the spacing between the 1st to 5th layers of positive and negative electrodes at the inner corners. This has a high probability of worsening the electrodynamics at this location, leading to lithium deposition, which in turn reduces the life of the battery cell and poor reliability.

[0093] 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 inventors 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 position 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.

[0094] In a battery cell of this structure, a buffer member including a buffer portion and an extension portion is provided. The buffer portion is provided in the central space formed by the winding of the separator and the electrode sheet and acts as a buffer. This can support the innermost electrode sheet during hot pressing of the core structure formed by the separator and the electrode sheet, thereby reducing the probability of brittle fracture during hot pressing of the winding structure and the probability of burrs, which is beneficial to improving the reliability of the electrode assembly and, in turn, the reliability of the battery cell. Under the support of the buffer portion, the distance between the electrode sheets at the innermost corner of the electrode assembly can also be reduced, reducing the probability of large gaps between the electrode sheets at the innermost corner of the electrode assembly, thereby reducing the probability of lithium plating. By providing the extension portion between the outer shell and the electrode assembly, the extension portion separates the electrode assembly and the outer shell, reducing the possibility of collision between the electrode assembly and the outer shell when assembled into the outer shell, reducing the probability of damage to the electrode assembly, thereby improving the reliability of the battery cell.

[0095] The battery disclosed in the embodiments of this application can be used, but is not limited to, in electrical devices such as vehicles, ships, or aircraft. A power supply system comprising the battery cell system disclosed in this application and batteries can be used to form the electrical device, thereby increasing the scope of application of the battery cell.

[0096] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0097] 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.

[0098] Please refer to Figure 1, which is a schematic structural diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. 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.

[0099] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0100] Please refer to Figure 2, which is an exploded view of the structure of a battery 100 provided in some embodiments of the present application. The battery 100 includes a housing 10 and a plurality of battery cells 20, which are intended to be accommodated within the housing 10. The housing 10 is used to provide an assembly space for the battery cells 20, and the housing 10 can adopt a variety of structures. In some embodiments, the housing 10 can include a first housing body 11 and a second housing body 12, which cover each other and together define an assembly space for accommodating the battery cells 20. The second housing body 12 can be a hollow structure with one end open, and the first housing body 11 can be a plate-like structure, with the first housing body 11 covering the open side of the second housing body 12, so that the first housing body 11 and the second housing body 12 jointly define an assembly space. The first housing body 11 and the second housing body 12 can also be hollow structures with one end open, with the open side of the first housing body 11 covering the open side of the second housing 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.

[0101] In the battery 100, the multiple battery cells 20 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure of the multiple battery cells 20 is housed within the housing 10. Alternatively, the battery 100 can be constructed by first connecting the multiple battery cells 20 in series, in parallel, or in a hybrid configuration to form a battery module, which is then connected in series, in parallel, or in a hybrid configuration to form a single structure and housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0102] Please refer to Figure 2, which is a schematic diagram of a partial structure 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 of the housing 10, with each row of battery cells 20 including multiple battery cells 20 arranged along the width of the housing 10; alternatively, the multiple rows of battery cells 20 are arranged along the width of the housing 10, with each row of battery cells 20 including multiple battery cells 20 arranged along the length of the housing 10.

[0103] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can be cylindrical, flat, rectangular, or in other shapes. For example, in FIG2 , the battery cell 20 is in the shape of a rectangular parallelepiped.

[0104] According to some embodiments of the present application, in a first aspect, referring to FIG. 3 , FIG. 4 and FIG. 5 , an embodiment of the present application provides a battery cell 20 , including: a housing 21 , an electrode assembly 22 and a buffer 23 .

[0105] The electrode assembly 22 is disposed within the housing 21 and includes a separator 221 and a pole piece 222. The separator 221 and pole piece 222 are stacked and wound to form a central space 22a 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 within 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.

[0106] The outer shell 21 may refer to the outer protective structure of the battery cell 20, which is used to enclose and protect the chemical substances and electrode assembly 22 within the battery cell 20. The outer shell 21 may be, but is not limited to, a circular shell, a square shell, etc., and may be, but is not limited to, made of one of aluminum, steel, and stainless steel.

[0107] The separator 221 and the electrode sheet 222 are wound together to form the electrode assembly 22 into a wound core structure. The central space 22a can refer to the central gap of the wound core structure. The central space 22a can be, but is not limited to, a cylindrical gap, a flat-plate gap, or the like. For example, when the wound core structure is cylindrical, the central space 22a can be a cylindrical gap; when the wound core structure is a flat wound structure, the central space 22a can be a flat-plate gap.

[0108] The electrode assembly 22 may include a pole piece 222. It should 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. In this embodiment, the pole piece 222 is a positive electrode sheet, and the positive electrode sheet and the separator 221 are stacked and wound to form a jellyroll structure. In this example, when the battery cell 20 is operating, 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.

[0109] The electrode assembly 22 may also include multiple electrode sheets 222. It is understood that in this embodiment, the multiple electrode sheets 222 may include a positive electrode sheet and a negative electrode sheet, with a separator 221 disposed between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet, separator 221, and negative electrode sheet are stacked and wound to form a core structure. The number of positive and negative electrode sheets may be, but is not limited to, two, three, four, or the like.

[0110] The buffer portion 231 may refer to a material or structure that has an elastic function, can shrink under pressure, and return to its original shape after the external force is removed, and is used 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. Referring to Figure 4, for example, the central space 22a may be a flat plate-shaped gap, and the buffer portion 231 may be a flat plate-shaped gap.

[0111] There may be one or more buffer portions 231. When there is only one buffer portion 231, the buffer portion 231 may be relatively large. For example, if the buffer portion 231 is a buffer plate, only one buffer plate is needed to fill the central space 22a, or even most of the central space 22a. When there are multiple buffer portions 231, the buffer portions 231 may be elongated buffer strips, and the multiple buffer strips may be spaced apart along the length of the central space 22a (the length of the central space 22a can be referred to as the third direction Z in FIG. 4 ).

[0112] The extension portion 232 may refer to the portion of the buffer member 23 that extends beyond the central space 22a. The extension portion 232 and the buffer portion 231 may have the same or different structures. The extension portion 232 separates the electrode assembly 22 from the outer casing 21, reducing the likelihood of hard contact between the electrode assembly 22 and the outer casing 21. This reduces the likelihood of the electrode assembly 22 being bumped when inserted into the outer casing, thereby improving the reliability of the electrode assembly 22. Furthermore, when the extension portion 232 and the buffer portion 231 have the same structure, the extension portion 232 also provides a buffering effect, further reducing the likelihood of collision between the electrode assembly 22 and the outer casing 21 and improving the reliability of the electrode assembly 22.

[0113] The extension portion 232 may be, but is not limited to, a circular sheet, a rectangular sheet, a strip sheet, and the like. Optionally, there may be one extension portion 232, in which case the extension portion 232 may be of a larger size, and one extension portion 232 may support most or all of the end faces of the electrode assembly 22. There may also be multiple extension portions 232, in which case the extension portions 232 may be long strips and arranged in rows and at intervals. Referring to FIG5 , illustratively, the extension portion 232 is in the shape of a rectangular sheet, and is one, and is provided 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.

[0114] It should be noted that in the above solution, the battery cell 20 may include multiple electrode assemblies 22, each of which is provided with a corresponding buffer 23. For example, referring to FIG3 , the battery cell 20 includes two electrode assemblies 22, each of which is provided with a buffer 23.

[0115] 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 charge and discharge process, increasing the inner ring curvature of the winding core structure, and reducing the probability of brittle fracture of the inner ring electrode 222. At the same time, the buffer portion 231 can also support the innermost ring electrode 222, reducing the probability of a large gap between two adjacent innermost ring electrode pieces 222, thereby reducing the probability of lithium plating, which is beneficial to extending the service life of the battery cell 20 and improving the safety 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.

[0116] In the above technical solution, a buffer member 23 is provided comprising a buffer portion 231 and an extension portion 232. The buffer portion 231 is disposed within the central space 22a formed by the winding of the separator 221 and the electrode piece 222 and acts as a buffer. This supports the innermost electrode piece 222 during hot pressing of the wound core structure formed by the separator 221 and the electrode piece 222, thereby reducing the probability of brittle fracture and burr formation during hot pressing of the wound structure. Furthermore, the support provided by the buffer portion 231 can also reduce the spacing between the electrode pieces at the innermost corners of the electrode assembly 22, reducing the probability of large gaps between the electrode pieces 222 at the innermost corners of the electrode assembly 22, thereby reducing the probability of lithium plating. This improves the reliability of the electrode assembly 22, and thus 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, 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.

[0117] In some embodiments of the present application, referring to FIG. 6 , the extension portion 232 includes a heat-conducting base 2321 . The heat-conducting base 2321 is connected to the buffer portion 231 and is attached to the housing 21 .

[0118] The heat-conducting base 2321 may be the main body of the extension portion 232 and has a heat-conducting function. The heat-conducting base 2321 may be, but is not limited to, a heat-conducting metal plate, a graphene plate, a heat-conducting silicone sheet, and the like.

[0119] Because the buffer portion 231 is located within the central space 22a of the electrode assembly 22, the contact surface between the buffer portion 231 and the electrode piece 222 is relatively large. Due to the high heat generation within the electrode assembly 22, heat generation is concentrated on the large surface and top of the electrode assembly 22. Therefore, the buffer portion 231 can transfer heat from the electrode assembly 22 to the thermally conductive substrate 2321, which in turn transfers the heat to the outer shell 21. The heat is then removed from the outer shell 21 by an external cooling device, which helps improve the heat dissipation efficiency of the battery cell 20. The external cooling device can be understood as a device that controls the temperature of the battery cell 20. Here, the cooling device can be, but is not limited to, a water cooling device.

[0120] In the above technical solution, by setting the extension portion 232 to include a heat-conducting base 2321, the extension portion 232 can also have a heat-conducting function and can increase the heat exchange surface area between the electrode assembly 22 and the outer shell 21, thereby quickly transferring the heat inside the electrode assembly 22 to the outer shell 21, 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, and being beneficial to slowing down the battery capacity attenuation, which can improve the reliability and performance of the battery cell 20.

[0121] In some embodiments of the present application, referring to FIG. 6 , the extension portion 232 further includes an insulating portion 2322 . The insulating portion 2322 is disposed on a side of the heat-conductive base 2321 close to the electrode assembly 22 and adheres to the electrode assembly 22 .

[0122] Insulating portion 2322 may be an insulating component, specifically a non-conductive material or coating that can be used to prevent the passage of current. When insulating portion 2322 is a non-conductive material, it may be made of, but not limited to, at least one of polyethylene, polypropylene, polyvinyl chloride, and paper tape. When insulating portion 2322 is a coating, it may be, but not limited to, aluminum oxide coating, titanium oxide coating, or the like.

[0123] The insulating portion 2322 may be, but is not limited to, an insulating sheet, an insulating film, an insulating coating, and the like. Specifically, when the insulating portion 2322 is an insulating sheet, both the insulating portion 2322 and the thermally conductive base 2321 may be sheet-like structures, thereby forming a double-layer structure. The insulating sheet and the thermally conductive base 2321 may be connected by, but is not limited to, bonding or snapping. When the insulating portion 2322 is an insulating film, the insulating film covers the thermally conductive base 2321, and the insulating film and the thermally conductive base 2321 may be connected by, but is not limited to, bonding. When the insulating portion 2322 is an insulating coating, the insulating coating is directly applied to the thermally conductive base 2321.

[0124] 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 thus 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.

[0125] In some embodiments of the present application, an insulating portion 2322 is provided on the side of the heat-conducting base 2321 close to the electrode assembly 22 and on the circumferential side surface arranged along the winding direction of the pole piece 222. In other words, the insulating portion 2322 can be provided not only on the large end surface of the heat-conducting base 2321 close to the electrode assembly 22, but also on the circumferential side surface of the heat-conducting base 2321. At this time, only one side of the heat-conducting base 2321 is exposed and in contact with the outer shell 21. In this way, the insulating portion 2322 can provide a better insulating effect on the heat-conducting base 2321, improve the insulation between the heat-conducting base 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.

[0126] In some embodiments of the present application, the thermal conductivity of the heat-conductive base 2321 may be greater than or equal to 50 W / (m·K).

[0127] 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.

[0128] In the above technical solution, by setting the thermal conductivity of the heat-conducting substrate 2321 to be greater than or equal to 50 W / (m·K), the heat-conducting substrate 2321 can have a higher thermal conductivity efficiency, so that the heat of the electrode assembly 22 can be transferred to the 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.

[0129] In some embodiments of the present application, referring to FIG. 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 provided around the circumference of the buffer portion 231 .

[0130] The protrusion 2323 may refer to a protruding portion of the insulating portion 2322. For example, taking the isolation film 221 and the pole piece 222 being wound around the first direction X as an example, the protrusion 2323 may refer to an annular structure disposed around the buffer portion 231 around the first direction X.

[0131] 3 and 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 breaking at the end portion in 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.

[0132] In the above technical solution, by providing the insulating part 2322 with a protrusion 2323, the protrusion 2323 can play an insulating and protective role in the connection area between the heat-conducting base 2321 and the buffer part 231, thereby reducing the probability of the connection area between the heat-conducting base 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 base 2321 when the end of the pole piece 222 is folded or damaged, thereby improving the reliability of the battery cell 20.

[0133] In some embodiments of the present application, referring to FIG. 6 , the protruding height of the protruding portion 2323 is H1, where 0 mm ≤ H1 ≤ 5 mm.

[0134] 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 2323 will be too high, which will affect the winding of the innermost pole piece 222 and make the protrusion 2323 too long, resulting in material waste.

[0135] In the above technical solution, by setting the protruding 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 of ​​the thermal conductive base 2321 and the buffer part 231, thereby providing better insulation protection, and at the same time reduce the manufacturing cost of the protrusion 2323.

[0136] In some embodiments of the present application, referring to FIG. 6 , the thickness of the insulating portion 2322 is T1 , where 0.1 mm ≤ T1 ≤ 1 mm.

[0137] 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.

[0138] 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 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.

[0139] 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 made 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.

[0140] In some embodiments of the present application, referring to FIG. 6 , the thickness of the thermally conductive substrate 2321 is T2, where 0.1 mm ≤ T2 ≤ 1 mm.

[0141] 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.

[0142] In the above technical solution, by setting the thickness T2 of the thermally conductive base 2321 within the range of 0.1 mm to 1 mm, the thickness T2 of the thermally conductive base 2321 is within an appropriate range. While having good support and thermal conductivity effects, the thickness of the thermally conductive base 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.

[0143] 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.

[0144] The extension portion 232 and the buffer portion 231 can 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 can have other functions. For example, the extension portion 232 can have a heat-conducting effect, quickly transferring the heat of the electrode assembly 22 to the outer shell 21; or, the extension portion 232 can have an insulating effect, and is used to separate the electrode assembly 22 and the outer shell 21, reducing the probability of electrical connection and short circuit between the electrode assembly 22 and the outer shell 21. Alternatively, the extension portion 232 can 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.

[0145] In the above example, the extending portion 232 and the buffer portion 231 may be connected by bonding, or the extending portion 232 and the buffer portion 231 may be connected by thermal bonding.

[0146] In the above technical solution, by providing the extension portion 232 and the buffer portion 231 as separate structures, the extension portion 232 can advantageously adopt a different structure and function than the buffer portion 231, thereby expanding the function of the buffer member 23. Alternatively, the extension portion 232 and the buffer portion 231 can have the same structure. However, since the extension portion 232 and the buffer portion 231 are separate structures, the extension portion 232 and the buffer portion 231 can be manufactured separately, which can reduce the difficulty of manufacturing the buffer member 23 and help reduce manufacturing costs.

[0147] In some embodiments of the present application, the extension portion 232 and the buffer portion 231 are integrally formed. For example, the buffer member 23 is in a T-shaped structure as a whole.

[0148] In the above technical solution, by providing the extension portion 232 and the buffer portion 231 as an integrally formed component, the structure of the buffer portion 23 is more stable, and the probability of separation between the extension portion 232 and the buffer portion 231 is relatively low. This facilitates the assembly of the extension portion 232 and the buffer portion 231 to the electrode assembly 22, and also facilitates the assembly of the buffer portion 23 and the electrode assembly 22 into the housing 21, thereby improving the assembly efficiency of the battery cell 20. Moreover, because the extension portion 232 and the buffer portion 231 are integrally formed, the extension portion 232 is less likely to shift within the housing 21, which improves the reliability of the extension portion 232 within the housing 21, thereby further improving the reliability of the battery cell 20.

[0149] In some embodiments of the present application, referring to FIG3 , 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 on a side of the electrode assembly 22 away from the pole ear 223 .

[0150] In this embodiment, the first direction X may be one of a length direction, a width direction, and a height direction of the battery cell 20. For example, referring to FIG3 , the first direction X is a height direction of the battery cell 20.

[0151] In the above technical solution, since the extension portion 232 and the tab 223 are located at both ends of the electrode assembly 22, the probability of mutual interference between the extension portion 232 and the tab 223 is relatively low, which facilitates bending one end of the electrode piece 222 to form the tab 223 and also facilitates the connection between the tab 223 and the electrode post 24. Moreover, the extension portion 232 will not be affected by the electrode piece 222, so on the one hand, the arrangement of the extension portion 232 is convenient, and on the other hand, the size of the extension portion 232 can be set relatively large, which can better support the electrode assembly 22.

[0152] In some embodiments of the present application, referring to FIG. 3 , the tab 223 is located at the top of the electrode assembly 22 , and the extension 232 is located at the bottom of the electrode assembly 22 and supported by the housing 21 .

[0153] In the above technical solution, the extension portion 232 can serve as a bottom support plate, supporting the electrode assembly 22 within the housing 21, thus providing a "two-in-one" function. This eliminates the need for a bottom support plate, reducing costs and simplifying the process of inserting the bottom support plate into the housing, thereby improving assembly efficiency. Because the buffer portion 231 is located within the central space 22a of the electrode assembly 22 and the extension portion 232 is connected to the buffer portion 231, the position of the extension portion 232 and the electrode assembly 22 is relatively fixed, which can reduce sliding friction between the electrode assembly 22 and the extension portion 232, thereby reducing the probability of wear on the electrode piece 222 and improving the reliability of the electrode assembly 22.

[0154] In some embodiments of the present application, referring to FIG5 , 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.

[0155] T3 can be, but is not limited to, 1 / 3R, 3 / 6R, 4 / 6R, 5 / 6R, R, and so on. 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 does not lift the electrode assembly 22 to a high height. The edge of the electrode assembly 22 is more likely to contact the rounded corner 21a, which can easily damage the electrode assembly 22, causing coating damage or a short circuit. If T3 is greater than R, the thickness of the extension 232 will be relatively large. Although the extension 232 does lift the electrode assembly 22 to a high height, 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 large volume within the outer shell 21, reducing the volume of the electrode assembly 22, which is not conducive to improving the volume energy density of the battery cell 20.

[0156] In the above technical solution, by setting the relationship between the thickness T3 of the extension portion 232 and the radius R of the rounded corner 21a of the outer shell 21 within the above range, the extension portion 232 can have a more suitable thickness. On the one hand, it can lift the electrode assembly 22 to a suitable height, reduce the probability of contact between the electrode assembly 22 and the rounded corner 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 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.

[0157] In some embodiments of the present application, referring to Figures 8 and 9, the isolation membrane 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 the side of the electrode assembly 22 close to the pole ear 223.

[0158] The electrode piece 222 is wound in the first direction X to form a multi-turn structure. Each turn of the electrode piece 222 is bent to form a tab 223. Then, the multiple tabs 223 are gathered together to form a larger tab group, which is electrically connected to the electrode post 24. In the related art, when the tabs of the electrode pieces are folded, the tabs may be electrically connected to adjacent electrode pieces, causing a short circuit (for example, the tab of the positive electrode piece may contact the negative electrode piece when bent, causing a short circuit).

[0159] 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 face 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 when the pole ear 223 is folded and causing a short circuit, thereby improving the reliability of the electrode assembly 22, thereby improving the reliability of the battery cell 20.

[0160] In some embodiments of the present application, referring to Figure 10, the isolation film 221 and the pole piece 222 are wound around the first direction X, the pole piece 222 is provided with a pole ear 223 at one end along the first direction X, and the electrode assembly 22 is provided with an extension portion 232 at both ends of the first direction X.

[0161] It can be understood that the buffer 23 is in an I-shaped structure, with the two ends of the buffer portion 231 connected to the extension portion 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.

[0162] Exemplarily, the extension portions 232 located at both ends of the first direction X of the electrode assembly 22 can both serve as an insulator, 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 serve as an insulator between the electrode ear 223 and the electrode piece 222, and the other can serve as an insulator between the electrode assembly 22 and the outer shell 21.

[0163] 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 heat-conducting base 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.

[0164] For example, one of the extensions 232 at both ends of the electrode assembly 22 in the first direction X can function as an insulator, while the other can function as a buffer. Regarding the buffering function, the structure of the extension 232 and the buffer 231 can be identical, thereby reducing the probability of the electrode assembly 22 colliding with the outer shell 21 when inserted into the shell.

[0165] 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; 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.

[0166] 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 portions 232 at both ends in the first direction X.

[0167] 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 .

[0168] 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.

[0169] In some embodiments of the present application, on a plane perpendicular to the first direction X, a projection of an 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.

[0170] In the above technical solution, it can be understood that the size of the extension portion 232 is relatively large, or it can be understood that the area of ​​the extension portion 232 away from the surface of the electrode assembly 22 is relatively large, so that 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 in contact and electrically connected to cause a short circuit.

[0171] In some embodiments of the present application, referring to Figures 10 and 11, the electrode ear 223 is located on one side of the extension portion 232 in the third direction Z, and 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.

[0172] In the above technical solution, the width of the extension portion 232 is at least greater than the thickness of the buffer portion 231. Thus, 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 the width of the electrode assembly 22, the width of the extension portion 232 can be reduced to a minimum, thereby reducing the impact of the extension portion 232 on the tab 223.

[0173] In some embodiments of the present application, referring to FIG11 , the electrode assembly 22 has a first surface 22b close to the extension portion 232, the extension portion 232 has a second surface 232a close to the first surface 22b, and the distance between the second surface 232a and the first surface 22b is H2, where 1mm≤H2≤3mm.

[0174] 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.

[0175] Because the winding core structure formed by the electrode sheets 222 is a multi-layer structure, and a tab 223 is folded onto each electrode sheet 222, and multiple tabs 223 are gathered to form a tab group, the base of the tab group near the electrode sheet 222 has a certain thickness. 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 insufficient to accommodate the base of the tab group, which is not conducive to the placement of the tab 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 may lead to space waste. Correspondingly, the position of the extension portion 232 relative to the electrode assembly 22 will be relatively high, and the extension portion 232 will be relatively large, occupying a relatively large space. This will affect the volume ratio of the electrode assembly 22 within the housing 21 and the volumetric energy density of the battery cell 20.

[0176] 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 tab 223 close to the pole piece 222. 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 to make the electrode assembly 22 have a larger volume share in the outer shell 21, thereby improving the volume energy density of the battery cell 20.

[0177] In some embodiments of the present application, referring to Figures 12 and 13, the electrode assembly 22 has multiple side surfaces, at least one of the multiple side surfaces is a first side surface 22c, the area of ​​the first side surface 22c is larger than the areas of the remaining 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.

[0178] "Side faces" may refer to surfaces that enclose the outer circumference of the electrode assembly 22. For example, when the first direction X is the height direction of the electrode assembly 22, the multiple side faces may refer to surfaces arranged around the first direction X. For example, when the electrode assembly 22 is a rectangular parallelepiped, the multiple side faces may refer to the left side, right side, front side, and rear side of the electrode assembly 22. The first side face 22c may refer to the surface with the largest area among the multiple side faces.

[0179] The first extension portion 233 may refer to a structure extending from the extension portion 232. The structure of the first extension portion 233 may be the same as or different from that of the extension portion 232. For example, the first extension portion 233 may have an insulating function, in which case the first extension portion 233 may include an insulating portion 2322; the first extension portion 233 may also have a thermally conductive function, in which case the first extension portion 233 may include a thermally conductive base 2321; or the first extension portion 233 may have both an insulating and a thermally conductive function, in which case the first extension portion 233 may include an insulating portion 2322 and a thermally conductive base 2321.

[0180] It can be understood that after the electrode assembly 22 is inserted into the shell, the electrode assembly 22 always interacts with the 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 shell 21, and the first extension portion 233 covers the first side surface 22c, which can separate the electrode assembly 22 and the shell 21, reducing the probability of electrical connection between the electrode assembly 22 and the shell 21, thereby reducing the probability of corrosion of the shell 21.

[0181] When there are multiple electrode assemblies 22, except for the two ends of the multiple electrode assemblies 22, they will be pressed against the outer shell 21, and any two adjacent electrode assemblies 22 will also interact and press 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, reducing the probability of damage caused by contact between the electrode assemblies 22, and can insulate the two adjacent electrode assemblies 22.

[0182] In the above technical solution, the first extension 233 can replace the insulating sheet to perform an insulating function, separating the electrode assembly 22 from surrounding components, providing better insulation for the electrode assembly 22 and reducing the probability of damage from contact between the electrode assembly 22 and surrounding components, thereby improving the reliability of the electrode assembly 22 and the reliability of the battery cell 20. Furthermore, the first extension 233 can reduce the use of insulating sheets in the battery cell 20, thereby reducing costs. At the same time, the first extension 233 can maintain a relatively fixed position with the electrode assembly 22, thereby facilitating the insertion of the electrode assembly 22 into the battery shell and improving the assembly efficiency of the battery cell 20.

[0183] In some embodiments of the present application, referring to FIG. 12 and FIG. 13 , the extension portion 232 is further provided with a second extension portion 234 . The second extension portion 234 is connected to the first extension portion 233 and is located on a side of the electrode assembly 22 close to the tab 223 .

[0184] The second extension portion 234 may be 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.

[0185] In the above technical solution, the second extension portion 234 can act as a separator between adjacent electrode assemblies 22, reducing the probability of the electrode ear 223 being inserted into the adjacent electrode assembly 22 when the electrode ear 223 is folded, causing electrical connection and short circuit, thereby improving the reliability of the electrode assembly 22 and thus improving the reliability of the battery cell 20.

[0186] In some embodiments of the present application, referring to Figures 12 and 13, the electrode ear 223 is located on one side of the second extension portion 234 in the third direction Z, and 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.

[0187] D3 can 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, failing to effectively prevent the tab 223 from being inserted into the battery cell 20. If D3 is larger than 3 / 2D1, the width of the second extension portion 234 is larger, resulting in redundant dimensions and occupying a larger space, which can affect the volumetric energy density of the battery cell 20. Furthermore, the weld mark of the tab 223 can be pulled, affecting the connection reliability between the tab 223 and the terminal 24, thereby affecting the reliability of the battery cell 20.

[0188] In the above technical solution, by setting the width D1 of the electrode assembly 22 and the width D3 of the second extension 234 within the above range, the second extension 234 can have an appropriate width range. On the one hand, the second extension 234 can have a larger size to block the tabs 223, reducing the probability of the tabs 223 being inserted into the adjacent electrode assembly 22 when bent, thereby reducing the probability of short circuits in the electrode assembly 22 and not affecting the welding of the tabs 223 and the posts 24, which is beneficial for improving the reliability of the battery cell 20. On the other hand, the volume of the second extension 234 within the housing 21 is not too large, which helps the electrode assembly 22 occupy a larger volume within the housing 21, thereby improving the volume energy density of the battery cell 20.

[0189] In some embodiments of the present application, referring to FIG. 4 , both ends of the buffer portion 231 extend to the corners of the pole piece 222 .

[0190] The "corners of the pole pieces 222" may refer to the bent regions of the pole pieces 222 located at both ends of the third direction Z and within the central space 22a. By extending both ends of the buffer portion 231 to the corners of the pole pieces 222, the buffer portion 231 can support the corners of the innermost pole pieces 222, further reducing the gap between the two innermost pole pieces 222, thereby minimizing the difference between the distance between the two innermost pole pieces 222 and the distance between the two outermost pole pieces 222.

[0191] For example, referring to Figure 4, the buffer portion 231 is located in the central space 22a, and can support the two corners of the innermost circle of the pole piece 222 in the third direction Z, and can also support the two large surfaces of the innermost circle of the pole piece 222 in the second direction Y. Therefore, the distance between the two innermost pole pieces 222 is relatively small, and the difference with the distance between the two outermost pole pieces 222 is not much, so the problem of lithium plating is not easy to occur.

[0192] In the above technical solution, by extending the two ends of the buffer portion 231 to the corners of the electrode piece 222, the buffer portion 231 can provide better support for the innermost electrode piece 222, which is beneficial to further reduce the distance between the two electrode pieces 222 at the innermost corner of the electrode assembly 22, and can further reduce the probability of lithium plating.

[0193] In some embodiments of the present application, referring to FIG. 6 , the buffer portion 231 includes an elastic portion 2311 and a heat conducting portion 2312 . The heat conducting portion 2312 is provided on at least one side of the elastic portion 2311 close to the pole piece 222 .

[0194] The elastic portion 2311 may be a structure or material that has an elastic effect, can shrink under pressure, and recover after the external force is removed. The elastic portion 2311 may be made of, but is not limited to, one or more materials such as EPS (expanded polystyrene), EPP (expanded polypropylene), and EPE (expanded polyethylene).

[0195] The heat-conducting portion 2312 may refer to a material or component capable of transferring heat. The heat-conducting portion 2312 may be, but is not limited to, a heat-conducting layer, a heat-conducting film, a heat-conducting sheet, and the like. The heat-conducting portion 2312 may be, but is not limited to, made of silicon carbide or a heat-conducting metal material. For example, when the heat-conducting portion 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 is not limited to, a copper foil layer or an aluminum foil layer, and the like.

[0196] There can be multiple heat conducting portions 2312 on the side of the elastic portion 2311, and the multiple heat conducting portions 2312 are spaced apart. For example, the heat conducting portions 2312 are heat conducting strips, and the multiple heat conducting strips are spaced apart along the third direction Z (see FIG4 ).

[0197] 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.

[0198] 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.

[0199] Exemplarily, referring to 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.

[0200] For another example, when the size of the central space 22a in the second direction Y is larger, the heat conducting part 2312 can be set not only on the side surfaces at both ends of the elastic part 2311 along the second direction Y, but also on the side surfaces at both ends of the elastic part 2311 along the third direction Z.

[0201] It can be understood that since the heat-conducting portion 2312 can contact the innermost electrode 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-conducting portion 2312, and the heat-conducting 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.

[0202] Optionally, referring to FIG6 , the extension portion 232 may include a thermally conductive base 2321 connected to the buffer portion 231 and attached to the outer shell 21 , with the thermally conductive portion 2312 connected to the thermally conductive base 2321 . Thus, the thermally conductive portion 2312 can quickly transfer heat from within the electrode assembly 22 to the thermally conductive base 2321, and then to the outer shell 21 via the thermally conductive base 2321 . The heat from the battery cell 20 is then quickly removed by an external cooling device. With this solution, the buffer portion 231 and the extension portion 232 have a high thermal conductivity, thereby further improving the heat dissipation efficiency of the battery cell 20 and effectively reducing the temperature rise of the battery cell 20 , further reducing side reactions within the battery, and thus further improving the reliability of the battery cell 20 .

[0203] In the above technical solution, by setting 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.

[0204] 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).

[0205] 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.

[0206] In the above technical solution, by setting the thermal conductivity of the heat-conducting portion 2312 to be greater than or equal to 50 W / (m·K), the heat-conducting portion 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.

[0207] 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 provided 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.

[0208] 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 surface between the heat-conducting part 2312 and the elastic part 2311 and the pole piece 222 can be made 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 also 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.

[0209] 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 -3mm≤H4-H3≤3mm.

[0210] 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.

[0211] If H4-H3 is less than -3mm, the size of the elastic portion 2311 is more than 3mm smaller than the size of the electrode assembly 22. Consequently, a relatively large portion of the electrode assembly 22 is not supported by the elastic portion 2311, which can easily lead to stress concentration at the end of the electrode assembly 22, significantly increasing the probability of fracture and burrs at the end of the electrode assembly 22 and seriously affecting the reliability of the electrode assembly 22. If H4-H3 is greater than 3mm, the size of the elastic portion 2311 is more than 3mm larger than the size of the electrode assembly 22. In this case, the portion of the elastic portion 2311 extending from the electrode assembly 22 is relatively long. Since the housing 21 is provided with a pole 24, and the pole piece 222 has a tab 223 connected to the pole 24 (see FIG. 3 ), a longer elastic portion 2311 can easily affect the arrangement of the tab 223, occupying more space and affecting the energy density of the battery cell 20.

[0212] In the above technical solution, by setting the difference between the height H4 of the elastic portion 2311 and the height H3 of the electrode assembly 22 within a range of -3 mm to 3 mm, the elastic portion 2311 can provide a larger support range for the innermost pole piece 222 of the electrode assembly 22, thereby reducing the probability of stress concentration occurring in the innermost pole piece 222 of the electrode assembly 22. It also reduces the probability of the elastic portion 2311 extending too far beyond the electrode assembly 22 and thus affecting the battery's energy density. Furthermore, the above solution can also ensure that the elastic portion 2311 has an appropriate processing tolerance range, which facilitates the processing and manufacturing of the elastic portion 2311, reduces the manufacturing difficulty of the elastic portion 2311, and improves the product yield.

[0213] In some embodiments of the present application, referring to Figure 7, the end of the elastic portion 2311 away from the extension portion 232 has a third surface 2311a, and the end of the heat-conducting portion 2312 away from the extension portion 232 has a fourth surface 2312a. In the first direction X, the height difference between the third surface 2311a and the fourth surface 2312a is H5, where 0mm≤H5≤5mm.

[0214] 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.

[0215] 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. The portion of the heat conducting portion 2312 extending beyond the elastic portion 2311 lacks support, hindering molding. Furthermore, the excess portion of the heat conducting portion 2312 affects the tab 223 and occupies a larger space within the housing 21, thereby affecting the energy density of the battery cell 20.

[0216] If H5 is greater than 5 mm, the height of the heat-conducting portion 2312 is much smaller than the height of the elastic portion 2311 , which may easily lead to a large gap between the elastic portion 2311 and the innermost electrode 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 .

[0217] In the above technical solution, by setting the difference between the third surface 2311a of the elastic part 2311 and the fourth surface 2312a of the heat-conducting part 2312 within the range of 0mm to 5mm, the effect of the excess elastic part 2311 of the heat-conducting part 2312 on the tab 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, and improving the reliability of the battery cell 20.

[0218] In some embodiments of the present application, referring to FIG. 7 , the thickness of the elastic portion 2311 is T4, where 0.5 mm ≤ T4 ≤ 3 mm.

[0219] 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, etc.

[0220] If the thickness T4 of the elastic portion 2311 is less than 0.5 mm, the elastic portion 2311 is relatively weak, providing poor support for the innermost pole piece 222. This effectively reduces the likelihood of brittle fracture of the innermost pole piece 222 and also effectively reduces the spacing between the two innermost pole pieces 222. If the thickness T4 of the elastic portion 2311 is greater than 3 mm, while the elastic portion 2311 provides good support, its increased thickness occupies a larger space, affecting the energy density of the battery cell 20.

[0221] 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. That is to say, the elastic part 2311 can have a relatively high strength, and the supporting effect on the innermost circle of the electrode assembly 22 is better. At the same time, the thickness of the elastic part 2311 can also be made more appropriate, which is beneficial to improving the energy density of the battery cell 20.

[0222] In some embodiments of the present application, referring to FIG. 7 , the thickness of the heat conducting portion 2312 is T5, where 10 μm ≤ T5 ≤ 500 μm.

[0223] The thickness T5 of the heat conducting 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 portion 2312 is less than 10 μm, the thickness of the heat-conducting portion 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 portion 2312 is greater than 500 μm, the thickness of the heat-conducting portion 2312 and the elastic portion 2311 is relatively large, which will occupy a larger space and affect the energy density of the battery cell 20.

[0224] 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. 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 heat-conducting 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.

[0225] According to the battery cell 20 provided in the embodiment of the present application, a T-shaped buffer structure is provided within the outer shell 21. The T-shaped buffer structure includes a buffer pad and a thermal pad. The buffer pad is disposed within the central space 22a of the core structure, and the thermal pad contacts the bottom of the core structure. The surface of the buffer pad is coated with a thermally conductive coating. The thermal pad includes a bottom thermally conductive layer and an insulating layer covering the bottom thermally conductive layer. The bottom thermally conductive layer is connected to the thermally conductive coating and contacts the bottom shell wall of the outer shell 21. The insulating layer is disposed at one end of the bottom thermally conductive layer near the core structure and has a protrusion 2323 extending to the buffer pad.

[0226] In a second aspect, an embodiment of the present application further provides a battery 100 , comprising the aforementioned battery cell 20 .

[0227] In the above technical solution, since the battery cell 20 has high reliability, the battery 100 having the battery cell 20 also has high reliability, which can reduce the probability of failure of the battery 100 during use and improve the performance of the battery 100.

[0228] In a third aspect, an embodiment of the present application further provides an electrical device, comprising the aforementioned battery cell 20 or battery 100 .

[0229] In the above technical solution, since the battery cell 20 and the battery 100 have high reliability, the electrical device having the battery cell 20 or the battery 100 can also have high power reliability, which can reduce the probability of power failure during use of the electrical device and improve the performance of the electrical device.

[0230] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0231] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery cell, characterized in that: include: shell; an electrode assembly disposed within the housing and comprising a separator and a pole piece, the separator and the pole piece being stacked and wound such that a central space is formed at the center of the electrode assembly; The buffer member includes 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 is arranged between the shell and the electrode assembly.

2. The battery cell according to claim 1, wherein: 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 provided on a side of the heat-conductive base 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 any one of claims 3 to 5, 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 heat-conducting substrate is T2, wherein 0.1 mm≤T2≤1 mm.

8. The battery cell according to any one of claims 2 to 7, characterized in that: The extension portion and the buffer portion are separate structures, and the extension portion and the buffer portion are connected by bonding or thermal compounding.

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

10. The battery cell according to any one of claims 1 to 9, 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 any one of claims 1 to 9, 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. The extension portion is provided on a side of the electrode assembly close to the pole ear.

14. The battery cell according to any one of claims 1 to 9, 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. The extension portions are provided at both ends of the electrode assembly located in the first direction.

15. The battery cell according to any one of claims 1 to 9, characterized in that: The isolation film and the pole piece are wound in a first direction. The pole piece is provided with pole ears at both ends along the first direction. The electrode assembly is provided with the extension parts at both ends 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 tab 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 tab 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 17, 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. A 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 18, 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 tab.

21. The battery cell according to claim 20, characterized in that The electrode tab 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. 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 any one of claims 1 to 21, 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, and the heat-conducting portion is provided 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 -3 mm ≤ H4 - H3 ≤ 3 mm.

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 conducting 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, where 0mm≤H5≤5mm.

27. The battery cell according to any one of claims 23 to 26, characterized in that: The thickness of the elastic portion is T4, wherein 0.5 mm ≤ T4 ≤ 3 mm.

28. The battery cell according to any one of claims 23 to 27, 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 the battery cell according to 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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