Electrode assembly, battery monomer, battery and electric equipment

Abstract

The embodiment of the invention provides an electrode assembly, a battery monomer, a battery and electric equipment. The electrode assembly comprises a first pole piece and a second pole piece, wherein the first pole piece comprises a plurality of first laminated sections and at least one first bent section; wherein the first bending section comprises a plurality of first nicks arranged along a second direction, the second direction is the extension direction of the first bending section, and the plurality of first nicks comprise first edge nicks positioned at two ends of the first pole piece along the second direction and first middle nicks positioned in the middle area of the first pole piece; the length of the first edge nick along the second direction is greater than the length of the first middle nick along the second direction. According to the electrode assembly, the battery monomer, the battery and the electric equipment provided by the embodiment of the invention, the processing efficiency and the qualified rate of the electrode assembly can be improved.

Description

Electrode assemblies, battery cells, batteries and electrical equipment Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an electrode assembly, a battery cell, a battery, and an electrical device. Background Art

[0002] With the continuous advancement of battery technology, various new energy industries using batteries as energy storage devices have experienced rapid development. In the development of battery technology, in addition to improving battery performance, improving safety and processing efficiency are also important issues that cannot be ignored. Therefore, how to improve battery processing efficiency and enhance battery safety are technical issues that need to be addressed in the development of battery technology.

[0003] Summary of the Invention

[0004] The embodiments of the present application provide an electrode assembly, a battery cell, a battery, and an electrical device, which can improve the processing efficiency and the qualified rate of the electrode assembly.

[0005] In a first aspect, an electrode assembly is provided, comprising: a first electrode sheet, the first electrode sheet comprising a plurality of first stacking segments and at least one first bending segment, the plurality of first stacking segments being stacked along a first direction, the first bending segment being used to connect two first stacking segments, the first electrode sheet being configured to bend at the first bending segment, the first direction being perpendicular to the first stacking segment; wherein the first bending segment comprises a plurality of first notches arranged along a second direction, the second direction being an extension direction of the first bending segment, the plurality of first notches comprising first edge notches located at both ends of the first electrode sheet along the second direction and a first middle notch located in a middle area of ​​the first electrode sheet, the length of the first edge notch along the second direction being greater than the length of the first middle notch along the second direction.

[0006] Therefore, the electrode assembly of the embodiment of the present application can, on the one hand, realize the positioning of the first bending section through the multiple first notches, thereby reducing the deviation of the first pole piece at the bending point. On the other hand, the multiple first notches can also reduce the difficulty of bending, reduce the resistance during bending, and thus improve the processing efficiency of the electrode assembly. In addition, considering that when the first bending section is bent, the resistance at the edge positions of the first pole piece at both ends along the second direction is greater than the resistance at the middle position of the first pole piece, and the fold fluctuation at the edge position of the first pole piece is greater, by setting the length of the first edge notch along the second direction to be greater than the length of the first middle notch along the second direction, the resistance at the edge position of the first pole piece can be further reduced, the fluctuation can be reduced, and the probability of the deviation of the first pole piece during bending can be further reduced, thereby improving the processing efficiency and qualified rate of the electrode assembly.

[0007] In some embodiments, along the first direction, the multiple first notches are located in the middle of the first bending section, so that the first pole piece is positioned more accurately when bent along the multiple first notches, and the offset of the pole piece is minimized to improve the processing efficiency and pass rate of the electrode assembly.

[0008] In some embodiments, the length of the first edge score along the second direction is greater than or equal to three times the length of the first middle score along the second direction; and / or the length of the first edge score along the second direction is less than or equal to five times the length of the first middle score along the second direction.

[0009] If the length of the first edge score along the second direction is less than three times the length of the first middle score along the second direction, the first edge score is too small and cannot effectively reduce the resistance of the edge region of the first electrode sheet during bending, and thus cannot effectively improve the processing efficiency of the electrode assembly. If the length of the first edge score along the second direction is greater than five times the length of the first middle score along the second direction, the first edge score is too large, which will reduce the structural strength of the first electrode sheet and thus affect the processing qualification rate of the electrode assembly.

[0010] In some embodiments, the plurality of first scores include a plurality of first intermediate scores, the plurality of first intermediate scores have equal lengths along the second direction, and / or the plurality of first intermediate scores have equal intervals along the second direction.

[0011] In this way, the multiple first middle notches are of equal length, which can reduce the number of times the dimensional accuracy of different first middle notches needs to be adjusted, thereby reducing processing difficulty. The multiple first middle notches are equally spaced and relatively evenly distributed along the second direction, which can ensure that the central area of ​​the first electrode sheet is subjected to uniform force along the second direction, making it easier to bend, reducing the processing difficulty of the electrode assembly, and thereby improving the processing efficiency and yield rate of the electrode assembly.

[0012] In some embodiments, one end of the first pole piece along the second direction includes a pole tab, and a length of a first edge notch near the pole tab along the second direction is smaller than a length of a first edge notch away from the pole tab along the second direction.

[0013] Taking into account that the thickness of the edge of the first pole piece close to the pole ear during processing is usually smaller than the thickness of the edge of the first pole piece away from the pole ear, by setting the length of the first edge notch close to the pole ear along the second direction to be smaller than the length of the first edge notch away from the pole ear along the second direction, the first edge notch away from the pole ear can more effectively reduce the bending resistance of the first pole piece at the edge position away from the pole ear, thereby reducing the processing difficulty of the electrode assembly, and thereby improving the processing efficiency and pass rate of the electrode assembly.

[0014] In some embodiments, a ratio of a distance between the first edge notch and the corresponding end of the first pole piece along the second direction to a length of the first pole piece along the second direction is in the range of [0.008, 0.02].

[0015] If the ratio is too small, the distance between the first edge notch and the edge of the corresponding first pole piece along the second direction will be too small. On the one hand, the strength of the area between the first edge notch and the edge of the first pole piece will be insufficient, which will reduce the structural strength of the first pole piece and affect the processing efficiency and performance of the electrode assembly. On the other hand, it will also increase the requirements for the processing accuracy of the corresponding first edge notch, increase the processing difficulty, and be detrimental to the processing efficiency of the electrode assembly. Therefore, the ratio should not be too small. On the contrary, if the ratio is too large, the distance between the first edge notch and the edge of the corresponding first pole piece along the second direction will be relatively too large, which will affect the effect of the first edge notch on reducing the bending resistance of the edge of the first pole piece, and cannot effectively reduce the bending difficulty of the electrode assembly, which is detrimental to the processing efficiency of the electrode assembly. Therefore, the ratio should not be too large.

[0016] In some embodiments, the distance between the first edge notch and the adjacent first middle notch is in the range of [1mm, 10mm]. If the distance is too large, that is, the distance between the first edge notch and the set first middle notch is large, then the area between the first edge notch and the adjacent first middle notch will still be subject to large resistance during the bending process, and will not be able to effectively reduce the resistance of the electrode assembly during the bending process, which is not conducive to improving the processing efficiency of the electrode assembly. On the contrary, if the distance is too small, that is, the distance between the first edge notch and the set first middle notch is small, then the structural strength of the area between the first edge notch and the set first middle notch is too low, which will affect the structural strength of the first electrode sheet and the structural strength of the electrode assembly; and the processing accuracy requirements for the first edge notch and the adjacent first middle notch are high, which will increase the processing difficulty of the electrode assembly, and thus affect the processing efficiency of the electrode assembly.

[0017] In some embodiments, the first notch is a through hole; alternatively, the first notch is a groove. If the first notch is a through hole, processing is facilitated and resistance during bending is significantly reduced, thereby improving the processing efficiency of the electrode assembly. If the first notch is a groove, resistance during bending is reduced and the loss of structural strength of the first electrode sheet of the electrode assembly is minimized.

[0018] In some embodiments, the first electrode sheet includes a plurality of first bent segments with different bending directions. By bending in different directions, a stacked electrode assembly is formed, which has a simple structure and is easy to implement.

[0019] In some embodiments, the multiple first bending sections include two first bending sections with opposite bending directions, and the first notches set in the two first bending sections have equal sizes along the bending direction, so that the forces on the multiple first bending sections bent along different bending directions are more uniform, the formed electrode assemblies are more uniform, the offset between different first stacking sections is reduced, and the processing rate and pass rate of the electrode assemblies are improved.

[0020] In some embodiments, the first electrode sheet includes multiple first bending segments, and the bending directions of the multiple first bending segments are the same; the size of the first notch set in the first bending segment close to the center of the electrode assembly among the multiple first bending segments along the bending direction is smaller than the size of the first notch set in the first bending segment away from the center of the electrode assembly along the bending direction.

[0021] Considering that the arc length of the first bending section located inside the electrode assembly along the bending direction is smaller, that is, the bending radius is smaller, while the arc length of the first bending section located outside the electrode assembly along the bending direction is larger, that is, the bending radius is larger, that is to say, the arc length of the first bending section along the bending direction gradually increases from the inside to the outside of the electrode assembly, then correspondingly, the size of the first notch set in the first bending section close to the center of the electrode assembly among the multiple first bending sections along the bending direction is smaller than the size of the first notch set in the first bending section away from the center of the electrode assembly along the bending direction. This can make the size of the first notch of the first bending section with a smaller arc length also smaller, and the size of the first notch of the first bending section with a larger arc length also larger. On the one hand, it is convenient for processing, and on the other hand, it can also improve the structural strength of the electrode assembly and reduce the problem of low local strength of the electrode assembly.

[0022] In some embodiments, the electrode assembly further comprises: a plurality of second electrode sheets having opposite polarity to the first electrode sheet, wherein the plurality of second electrode sheets are alternately stacked with the plurality of first stacked sections along the first direction. Thus, when bending the electrode assembly, the second electrode sheets do not need to be bent, thereby reducing the number of bending layers and making bending easier.

[0023] In some embodiments, along a third direction, the first bend section corresponds to at least one second electrode piece, and along the first direction, the size of the first notch is smaller than or equal to the size of the corresponding at least one second electrode piece, and the third direction is perpendicular to the first and second directions. Thus, by setting the size of the first notch along the first direction to be smaller than or equal to the size of the corresponding at least one second electrode piece along the first direction, the second electrode piece is prevented from protruding from the first notch, thereby reducing the phenomenon of active material precipitation caused by the first notch being too large, and also reducing the impact on the performance of the electrode assembly.

[0024] In some embodiments, the electrode assembly further comprises: a second electrode sheet having a polarity opposite to that of the first electrode sheet, wherein the first electrode sheet and the second electrode sheet are wound around a winding axis. This can reduce the need for repeated cutting of the second electrode sheet before winding, thereby speeding up the processing of the electrode assembly.

[0025] In some embodiments, the second pole piece includes a plurality of second stacked segments and at least one second bent segment, the second bent segment is used to connect two adjacent second stacked segments, the second bent segment includes a plurality of second notches arranged along the second direction, the plurality of second notches include second edge notches located at both ends of the second pole piece along the second direction and a second middle notch located in the middle area of ​​the first pole piece, the length of the second edge notch along the second direction is greater than the length of the second middle notch along the second direction.

[0026] The second bending section includes a plurality of second notches arranged along the second direction. On the one hand, the second bending section can be positioned by the plurality of second notches, reducing the offset of the second pole piece at the bend, thereby reducing the offset between different pole pieces of the electrode assembly; on the other hand, the plurality of second notches can also reduce the difficulty of bending, reduce the resistance during bending, and thereby improve the processing efficiency of the electrode assembly. In addition, considering that when the second bending section is bent, the resistance at the edge positions of the second pole piece at both ends along the second direction is greater than the resistance at the middle position of the second pole piece, and the fluctuation of the fold at the edge position of the second pole piece is greater, by setting the length of the second edge notch along the second direction to be greater than the length of the second middle notch along the second direction, the resistance at the edge position of the second pole piece can be further reduced, the fluctuation can be reduced, and the probability of the second pole piece offset during bending can be further reduced, thereby reducing the possibility of failure of the electrode assembly and improving the processing efficiency and qualified rate of the electrode assembly.

[0027] In some embodiments, the size of the notch set in the bending section close to the center of the electrode assembly in multiple first bending sections and at least one second bending section along the bending direction is smaller than the size of the notch set in the bending section away from the center of the electrode assembly along the bending direction.

[0028] Since the arc lengths of the first bending section of the first pole piece and the second bending section of the second pole piece gradually increase along the radial direction from the inside to the outside of the electrode assembly, that is, the bending radius gradually increases, then the corresponding sizes of the first notch and the second notch along the bending direction also gradually increase along the radial direction from the inside to the outside of the electrode assembly. The size of the notch set in the bending section with a smaller arc length can be smaller, and the size of the notch set in the bending section with a larger arc length can be larger. On the one hand, it is convenient for processing, and on the other hand, it can also improve the structural strength of the electrode assembly and reduce the problem of low local strength of the electrode assembly.

[0029] In some embodiments, the second electrode sheet is a positive electrode sheet, which can also reduce the impact on the performance of the electrode assembly.

[0030] In some embodiments, the positive electrode plate includes a positive electrode active material layer, and the material of the positive electrode active material layer includes at least one of the following: Prussian blue-type sodium ion positive electrode material, layered oxide sodium ion positive electrode material and polyanion sodium electrode material. The electrode assembly and battery cell formed using this positive electrode active material layer have better high temperature resistance and reduce the possibility of battery cells exploding at high temperatures.

[0031] In some embodiments, the first electrode sheet is a negative electrode sheet, which can also reduce the impact on the performance of the electrode assembly.

[0032] In some embodiments, the negative electrode sheet includes a negative current collector, the surface of which is not coated with negative active material. This reduces the overall thickness of the negative electrode sheet, resulting in a lighter and smaller electrode assembly. Alternatively, while reducing the overall thickness of the negative electrode sheet, the thickness of the positive electrode sheet can be increased. For example, the thickness of the positive active material layer of the positive electrode sheet can be increased, thereby increasing the energy density of the battery cell including the electrode assembly.

[0033] In a second aspect, a battery cell is provided, comprising: the electrode assembly described in the first aspect.

[0034] In a third aspect, a battery is provided, comprising: a plurality of battery cells, wherein the battery cells include the electrode assembly described in the first aspect.

[0035] In a fourth aspect, an electrical device is provided, comprising: a battery, the battery comprising the electrode assembly described in the first aspect, the battery being used to provide electrical energy to the electrical device.

[0036] In some embodiments, the electrical equipment is a vehicle, a ship, or a spacecraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a schematic structural diagram of a vehicle disclosed in one embodiment of the present application;

[0038] FIG2 is a schematic diagram of the exploded structure of a battery disclosed in one embodiment of the present application;

[0039] FIG3 is a schematic structural diagram of a plurality of battery cells included in a battery disclosed in an embodiment of the present application;

[0040] FIG4 is a schematic structural diagram of a battery cell disclosed in an embodiment of the present application;

[0041] FIG5 is a schematic diagram of the exploded structure of a battery cell disclosed in one embodiment of the present application;

[0042] FIG6 is a cross-sectional schematic diagram of an electrode assembly disclosed in one embodiment of the present application;

[0043] FIG7 is a cross-sectional schematic diagram of another electrode assembly disclosed in an embodiment of the present application;

[0044] FIG8 is a cross-sectional schematic diagram of another electrode assembly disclosed in an embodiment of the present application;

[0045] FIG9 is a schematic structural diagram of an unfolded first pole piece disclosed in one embodiment of the present application;

[0046] FIG10 is a partial cross-sectional schematic diagram of a first pole piece disclosed in one embodiment of the present application;

[0047] FIG11 is a partial cross-sectional schematic diagram of a second pole piece disclosed in an embodiment of the present application.

[0048] In the drawings, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0049] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0050] In the description of this application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly perpendicular, but is within the allowable error range. "Parallel" is not strictly parallel, but is within the allowable error range.

[0051] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of this application. In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0052] 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.

[0053] 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.

[0054] 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 a battery pack. A battery generally includes a casing for enclosing one or more battery cells. The casing can reduce the impact of liquids or other foreign matter on the charging or discharging of the battery cells.

[0055] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0056] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0057] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0058] In some embodiments, the negative electrode may be a negative electrode sheet, which may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0059] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0060] In some embodiments, the negative electrode may be a metal foam. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam. When the metal foam is used as the negative electrode sheet, the surface of the metal foam may or may not be provided with a negative electrode active material.

[0061] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0062] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0063] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0064] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on needs. The electrolyte can be liquid, gel, or solid.

[0065] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0066] In some embodiments, the electrode assembly is a laminated structure. In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include positive tabs and negative tabs.

[0067] During the processing of the electrode assembly, if it is necessary to bend at least one electrode sheet in the electrode assembly, for example, taking a wound electrode assembly as an example, when bending the bending corner area of ​​the wound electrode assembly, it is easy to have uneven force problems, which in turn leads to misalignment between different layers of electrode sheets. The misaligned electrode sheets are prone to the problem of active material precipitation, which in turn affects the processing efficiency and processing qualification rate of the electrode assembly.

[0068] Therefore, an embodiment of the present application provides an electrode assembly, which includes a first pole piece, the first pole piece including a plurality of first stacked sections and at least one bending section, the plurality of first stacked sections being stacked along a first direction, and the first direction being perpendicular to the first stacked sections. The first bending section is used to connect two first stacked sections, and the first pole piece can be bent at the first bending section. The first bending section includes a plurality of first notches arranged along a second direction, and the second direction is the extension direction of the first bending section. On the one hand, the first bending section can be positioned by the plurality of first notches, reducing the offset of the first pole piece at the bending point. On the other hand, the plurality of first notches can also reduce the difficulty of bending, reduce the resistance during bending, and thereby improve the processing efficiency of the electrode assembly.

[0069] In addition, the multiple first notches include first edge notches located at both ends of the first pole piece along the second direction, and also include a first middle notch located in the middle area of ​​the first pole piece, and the length of the first edge notch along the second direction is greater than the length of the first middle notch along the second direction. Considering that when the first bending section is bent, the resistance at the edge positions of the two ends of the first pole piece along the second direction is greater than the resistance at the middle position of the first pole piece, and the fluctuation of the fold at the edge position of the first pole piece is greater, by setting the length of the first edge notch along the second direction to be greater than the length of the first middle notch along the second direction, the resistance at the edge position of the first pole piece can be further reduced, the fluctuation can be reduced, and the probability of the first pole piece shifting when bending can be further reduced, which can also reduce the possibility of active material precipitation and improve the processing efficiency and qualified rate of the electrode assembly.

[0070] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use batteries.

[0071] Electrical equipment can be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and electric tools, etc. Vehicles can be fuel vehicles, gas vehicles, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical equipment.

[0072] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0073] For example, as shown in FIG1 , it is a structural schematic diagram of a vehicle 1 according to an embodiment of the present application. The vehicle 1 may be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A motor 40, a controller 30 and a battery 10 may be provided inside the vehicle 1. The controller 30 is used to control the battery 10 to supply power to the motor 40. For example, a battery 10 may be provided at the bottom, front or rear of the vehicle 1. The battery 10 may be used to power the vehicle 1. For example, the battery 10 may be used as an operating power source for the vehicle 1, for the circuit system of the vehicle 1, for example, for the working power requirements during the start-up, navigation and operation of the vehicle 1. In another embodiment of the present application, the battery 10 may not only be used as an operating power source for the vehicle 1, but also as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0074] To meet different power requirements, a battery can include multiple battery cells, which can be connected in series, parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections. A battery can also be referred to as a battery pack. Alternatively, multiple battery cells can be connected in series, parallel, or in a hybrid configuration to form a battery module, which can then be connected in series, parallel, or in a hybrid configuration to form a battery. In other words, multiple battery cells can be directly connected to form a battery, or they can be first connected to form battery modules, which can then be connected to form a battery.

[0075] For example, Figure 2 shows a schematic structural diagram of a battery 10 according to an embodiment of the present application. The battery 10 may include a plurality of battery cells 20; Figure 3 shows a schematic diagram of the plurality of battery cells 20 included in the battery 10. As shown in Figures 2 and 3, the battery 10 may further include a case 11, the interior of the case 11 being a hollow structure, and the plurality of battery cells 20 being accommodated in the case 11. Figure 2 shows a possible implementation of the case 11 according to an embodiment of the present application. As shown in Figure 2, the case 11 may include two parts, referred to herein as a first part 111 and a second part 112, which are snapped together. The shapes of the first part 111 and the second part 112 may be determined according to the shape of the battery module 200 combination, and at least one of the first part 111 and the second part 112 has an opening. For example, as shown in Figure 2, the first part 111 and the second part 112 can both be hollow rectangular parallelepipeds and each has only one open face. The opening of the first part 111 and the opening of the second part 112 are arranged opposite to each other, and the first part 111 and the second part 112 are interlocked to form a box body 11 with a closed chamber.

[0076] For another example, unlike that shown in Figure 2, only one of the first portion 111 and the second portion 112 may be a hollow rectangular parallelepiped with an opening, while the other may be a plate-shaped structure to cover the opening. For example, assuming that the second portion 112 is a hollow rectangular parallelepiped with only one open face, and the first portion 111 is a plate-shaped structure, the first portion 111 covers the opening of the second portion 112 to form a case 11 having a closed chamber, which can be used to accommodate multiple battery cells 20. The multiple battery cells 20 are connected in parallel, series, or in a mixed combination and then placed in the case 11 formed by the first portion 111 and the second portion 112 being fastened together.

[0077] Optionally, the battery 10 may also include other structures, which will not be described in detail here. For example, as shown in Figures 2 and 3, the battery 10 may also include a busbar 12, which is used to achieve electrical connection between multiple battery cells 20, such as parallel connection, series connection, or mixed connection. Specifically, the busbar 12 can achieve electrical connection between the battery cells 20 by connecting the electrode terminals 214 of the battery cells 20. Furthermore, the busbar 12 can be fixed to the electrode terminals 214 of the battery cells 20 by welding. The electrical energy of the multiple battery cells 20 can be further led out through the box 11 through a conductive mechanism.

[0078] The number of battery cells 20 in the battery 10 can be set to any value based on different power requirements. Multiple battery cells 20 can be connected in series, parallel, or in a hybrid manner to achieve higher capacity or power. Since each battery 10 may include a large number of battery cells 20, for ease of installation, the battery cells 20 can also be grouped, with each group of battery cells 20 forming a battery module. The number of battery cells 20 included in a battery module is not limited and can be set according to requirements.

[0079] Figure 4 is a schematic diagram of the structure of a battery cell 20 according to one embodiment of the present application, and Figure 5 is a schematic diagram of a partially exploded structure of a battery cell 20 according to one embodiment of the present application. For example, the battery cell 20 shown in Figure 5 may be any of the battery cells 20 shown in Figures 2 to 4 . As shown in Figures 4 and 5 , the battery cell 20 according to this embodiment of the present application may include a housing 21. Specifically, the housing 21 may include a shell 211 having a hollow structure with at least one opening; a cover plate 212 for covering the opening of the shell; and an electrode assembly 22 housed within the shell 21.

[0080] It should be understood that the housing 211 of the present embodiment is a component for accommodating the electrode assembly 22. The housing 211 may be a hollow structure with an opening at one end or at multiple ends. For example, if the housing 211 is a hollow structure with an opening at one end, a single cover plate 212 may be provided. If the housing 211 is a hollow structure with openings at opposite ends, two cover plates 212 may be provided, with the two cover plates 212 respectively covering the openings at both ends of the housing 211.

[0081] The housing 211 can be in various shapes, such as a cylinder, a cuboid, or other polyhedron. For example, as shown in Figures 4 and 5, in the embodiments of the present application, the housing 211 is mainly described as a cuboid structure, and the housing 211 is a hollow structure with an opening at one end.

[0082] It should be understood that the cover plate 212 of the present embodiment is used to cover the opening of the housing 211 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the cover plate 212 can be adapted to the shape of the housing 211. As shown in Figures 4 and 5, the housing 211 is a rectangular parallelepiped structure, and the cover plate 212 is a rectangular plate structure adapted to the housing 211.

[0083] In the embodiment of the present application, the housing 211 can be made of a variety of materials, such as copper, iron, aluminum, steel, and aluminum alloys. The cover plate 212 can also be made of a variety of materials, such as copper, iron, aluminum, steel, and aluminum alloys. Optionally, the material of the cover plate 212 can be the same as or different from that of the housing 211.

[0084] It should be understood that the battery cell 20 also includes an electrode terminal 214. The electrode terminal 214 of the embodiment of the present application is used to electrically connect to the electrode assembly 22 inside the battery cell 20 to output the electrical energy of the battery cell 20. As shown in Figures 4 and 5, the battery cell 20 may include at least two electrode terminals 214, and the at least two electrode terminals 214 may include at least one positive electrode terminal 214a and at least one negative electrode terminal 214b. The positive electrode terminal 214a is used to electrically connect to the positive electrode tab 222a of the electrode assembly 22, and the negative electrode terminal 214b is used to electrically connect to the negative electrode tab 222b of the electrode assembly 22. The positive electrode terminal 214a and the positive electrode tab 222a can be directly or indirectly connected, and the negative electrode terminal 214b and the negative electrode tab 222b can be directly or indirectly connected. Illustratively, the positive electrode terminal 214a may be electrically connected to the positive electrode tab 222a via a connecting member, and the negative electrode terminal 214b may be electrically connected to the negative electrode tab 222b via a connecting member.

[0085] In the battery cell 20, the electrode assembly 22 is the component where the electrochemical reaction occurs. Depending on actual usage requirements, the number of electrode assemblies 22 within the housing 211 can be one or more. For example, as shown in Figures 4 and 5, two electrode assemblies 22 are provided within the battery cell 20. The electrode assembly 22 can be cylindrical, rectangular, or similar. If the electrode assembly 22 is cylindrical, the housing 211 can also be cylindrical. If the electrode assembly 22 is rectangular, the housing 211 can also be rectangular.

[0086] It should be understood that, as shown in Figures 4 and 5, the electrode assembly 22 includes a tab 222 and an electrode body 221, wherein the tab 222 of the electrode assembly 22 may include a positive tab 222a and a negative tab 222b, the positive tab 222a may be formed by stacking the portion of the positive electrode sheet that is not coated with the positive electrode active material layer, and the negative tab 222b may be formed by stacking the portion of the negative electrode sheet that is not coated with the negative electrode active material layer; the electrode body 221 may be formed by stacking or winding the positive electrode sheet and the negative electrode sheet.

[0087] Figures 6 to 8 respectively illustrate cross-sectional schematic diagrams of electrode assemblies 22 according to different embodiments of the present application. The electrode assemblies 22 shown in Figures 6 to 8 have different structures, but the cross-sections shown are cross-sections taken in the same direction of the electrode assembly 22. For example, the cross-sections in Figures 6 to 8 may be parallel to the end surface of the electrode tab 222 as shown in Figure 5. Figure 9 illustrates a partially expanded schematic diagram of a first electrode piece 31 included in the electrode assembly 22 according to an embodiment of the present application. For example, the first electrode piece 31 shown in Figure 9 may be a partial schematic diagram of any electrode piece of the electrode assembly 22 shown in Figures 6 to 8.

[0088] As shown in Figures 6 to 9, the electrode assembly 22 of the embodiment of the present application includes: a first electrode piece 31, the first electrode piece 31 includes a plurality of first stacking sections 312 and at least one first bending section 311, the plurality of first stacking sections 312 are stacked along a first direction X, the first bending section 311 is used to connect two first stacking sections 312, the first electrode piece 31 is configured to bend at the first bending section 311, and the first direction X is perpendicular to the first stacking section 312; wherein, the first bending section 311 is configured to bend at the first bending section 311. The bend section 311 includes a plurality of first notches 313 arranged along a second direction Y, where the second direction Y is the extension direction of the first bend section 311. The plurality of first notches 313 include a first edge notch 3131 located at both ends of the first pole piece 31 along the second direction Y and a first middle notch 3132 located in the middle area of ​​the first pole piece 31. The length L1 of the first edge notch 3131 along the second direction Y is greater than the length L2 of the first middle notch 3132 along the second direction Y.

[0089] It should be understood that the first electrode piece 31 of the embodiment of the present application can be any electrode piece of the electrode assembly 22, for example, it can be the positive electrode piece or the negative electrode piece of the electrode assembly 22. For ease of description, Figures 6 to 8 illustrate the first electrode piece 31 as an example of a negative electrode piece, but the embodiment of the present application is not limited to this.

[0090] As shown in Figures 6 to 8, for the electrode assembly 22, the first stacking section 312 of the embodiment of the present application is a relatively flat area of ​​the first electrode piece 31 of the electrode assembly 22, and the first bending section 311 is a bent area of ​​the first electrode piece 31 of the electrode assembly 22. Specifically, for the unfolded first electrode piece 31 as shown in Figure 9, the first stacking section 312 and the first bending section 311 are interconnected and arranged at intervals, that is, two first bending sections 311 are connected to each other at both ends of each first stacking section 312, and two first bending sections 311 are connected to each other at both ends of the first stacking section 312. When assembling the electrode assembly 22, the first electrode piece 31 is bent at the first bending section 311, and the multiple first stacking sections 312 are stacked along the first direction X to form the electrode assembly 22, wherein the first direction is a direction perpendicular to the first stacking section 312.

[0091] It should be understood that the first bent section 311 of the present embodiment includes a plurality of first notches 313 arranged along a second direction Y. As shown in FIG9 , the second direction Y is the extension direction of the first bent section 311; that is, the second direction Y is perpendicular to the edge of the first electrode sheet 31 where the tab 222 is located, that is, perpendicular to the end face of the electrode assembly 22 where the tab 222 is located; that is, the second direction Y is the width direction of the first electrode sheet 31. Furthermore, the second direction Y is perpendicular to the first direction X.

[0092] In the embodiment of the present application, the plurality of first notches 313 include first edge notches 3131 located at both ends of the first pole piece 31 along the second direction Y. Specifically, the second direction Y in the embodiment of the present application includes vertically upward and vertically downward as shown in FIG9 , and the ends of the first pole piece 31 along the second direction Y include the upper edge and the lower edge of the first pole piece 31. Therefore, the plurality of first notches 313 include at least one first edge notch 3131 located at the upper edge and / or at least one first edge notch 3131 located at the lower edge.

[0093] In addition, if the plurality of first notches 313 includes a plurality of first edge notches 3131, the length L1 of the first edge notches 3131 along the second direction Y in the embodiment of the present application may refer to the average, minimum, or maximum value of the lengths of the plurality of first edge notches 3131 along the second direction Y. For example, as shown in FIG9 , taking the plurality of first notches 313 as an example, where the plurality of first notches 313 includes two first edge notches 3131, the length of the upper first edge notch 3131 along the second direction Y is L11, and the length of the lower first edge notch 3131 along the second direction Y is L12, the length L1 of the first edge notch 3131 along the second direction Y in the embodiment of the present application may be the minimum value between the lengths L11 and L12, but the embodiment of the present application is not limited thereto.

[0094] Similar to the first edge score 3131, the plurality of first scores 313 in the embodiment of the present application may include at least one first middle score 3132 located in the middle region of the first pole piece 31. If the plurality of first scores 313 include multiple first middle scores 3132, the length L2 of the first middle score 3132 along the second direction Y in the embodiment of the present application may refer to the average, minimum, or maximum value of the lengths of the plurality of first middle scores 3132 along the second direction Y. For example, as shown in FIG9 , taking the plurality of first scores 313 as an example, where the lengths of the five first middle scores 3132 along the second direction Y are L21, L22, L23, L24, and L25, respectively, from top to bottom, the length L2 of the first middle score 3132 along the second direction Y in the embodiment of the present application may be the maximum value among the lengths L21 to L25, but the embodiment of the present application is not limited thereto.

[0095] Therefore, in the embodiment of the present application, the first bending section 311 includes a plurality of first notches 313 arranged along the second direction Y. On the one hand, the first bending section 311 can be positioned through the plurality of first notches 313, thereby reducing the offset of the first pole piece 31 at the bending point, thereby reducing the offset between different pole pieces of the electrode assembly 22; on the other hand, the plurality of first notches 313 can also reduce the difficulty of bending, reduce the resistance during bending, and thereby improve the processing efficiency of the electrode assembly 22. In addition, considering that when the first bending section 311 is bent, the resistance at the edge positions of the two ends of the first pole piece 31 along the second direction Y is greater than the resistance at the middle position of the first pole piece 31, and the fold fluctuation at the edge position of the first pole piece 31 is greater, by setting the length L1 of the first edge notch 3131 along the second direction Y to be greater than the length L2 of the first middle notch 3132 along the second direction Y, the resistance at the edge position of the first pole piece 31 can be greatly reduced, the fluctuation can be reduced, and the probability of the first pole piece 31 deflecting when bending can be further reduced, which can also reduce the possibility of active material precipitation or failure of the electrode assembly 22, and improve the processing efficiency and qualified rate of the electrode assembly 22.

[0096] In the embodiment of the present application, the plurality of first notches 313 are located in the middle of the first bending section 311 along the first direction X. Specifically, as shown in Figures 6 to 9, the plurality of first notches 313 are located in the middle of the first bending section 311 along the first direction X, or in other words, the plurality of first notches 313 are located in the middle of the first bending section 311 along the bending direction W, so that the first electrode piece 31 is more accurately positioned when it is bent along the plurality of first notches 313, and the deviation of the electrode piece is minimized, thereby improving the processing efficiency and the yield rate of the electrode assembly 22.

[0097] It should be understood that the bending direction W in the embodiment of the present application may include a clockwise direction W1 and a counterclockwise direction W2, and, as shown in Figures 6 to 9, the first electrode piece 31 may include multiple first bending sections 311 having the same or different bending directions. For example, for different types of electrode assemblies 22, the first electrode piece 31 may include first bending sections 311 having the same bending direction, or the first electrode piece 31 may include first bending sections 311 having different bending directions. The embodiment of the present application is not limited to this.

[0098] It should be understood that the length L1 of the first edge notch 3131 along the second direction Y of the embodiment of the present application can be flexibly set according to the actual application. In addition, if the first bending section 311 includes multiple first edge notches 3131, the lengths of the multiple first edge notches 313 along the second direction Y can be equal or unequal, and the positions of the multiple first edge notches 313 along the second direction Y can also be flexibly set according to the actual application. Similarly, the length L2 of the first intermediate notch 3132 along the second direction Y of the embodiment of the present application can also be flexibly set according to the actual application. In addition, if the first bending section 311 includes multiple first intermediate notches 3132, the lengths of the multiple first intermediate notches 3132 along the second direction Y can be equal or unequal, and the positions of the multiple first intermediate notches 3132 along the second direction Y can also be flexibly set according to the actual application. This will be explained below with reference to several specific embodiments.

[0099] Optionally, as an embodiment, the length L1 of the first edge score 3131 along the second direction Y is greater than or equal to three times the length L2 of the first intermediate score 3132 along the second direction Y; and / or the length L1 of the first edge score 3131 along the second direction Y is less than or equal to five times the length L2 of the first intermediate score 3132 along the second direction Y. Specifically, if the length L1 of the first edge score 3131 along the second direction Y is less than three times the length L2 of the first intermediate score 3132 along the second direction Y, the size of the first edge score 3131 is too small and cannot effectively reduce the resistance of the edge region of the first electrode sheet 31 during the bending process, thereby failing to effectively improve the processing efficiency of the electrode assembly 22. If the length L1 of the first edge score 3131 along the second direction Y is greater than five times the length L2 of the first intermediate score 3132 along the second direction Y, the size of the first edge score 3131 is too large, which will reduce the structural strength of the first electrode sheet 31 and thus affect the processing qualification rate of the electrode assembly 22.

[0100] Optionally, as an embodiment, when the plurality of first score marks 313 includes a plurality of first intermediate score marks 3132, the lengths of the plurality of first intermediate score marks 3132 along the second direction Y are equal, and / or the intervals between the plurality of first intermediate score marks 3132 along the second direction Y are equal. Specifically, as shown in FIG6 to FIG9 , taking the plurality of first score marks 313 including five first intermediate score marks 3132 as an example, in order from top to bottom, the lengths of the five first intermediate score marks 3132 along the second direction Y are L21, L22, L23, L24, and L25, respectively. Therefore, the five first intermediate score marks 3132 can be set to have the same lengths L21, L22, L23, L24, and L25. In addition, in order from top to bottom, the lengths of the spacing between the five first intermediate marks 3132 along the second direction Y are D12, D23, D34 and D45 respectively. The five first intermediate marks 3132 can also be set to satisfy the lengths D12, D23, D34 and D45 are equal.

[0101] In this way, by setting the lengths of multiple first intermediate notches 3132 along the second direction Y to be equal, the number of times the dimensional accuracy of different first intermediate notches 3132 is adjusted can be reduced, thereby reducing the processing difficulty; by setting the intervals of multiple first intermediate notches 3132 along the second direction Y to be equal, that is, the first intermediate notches 3132 are evenly distributed along the second direction Y, the middle area of ​​the first pole piece 31 can be evenly stressed along the second direction Y and easy to bend, thereby reducing the processing difficulty of the electrode assembly 22 and thereby improving the processing efficiency and pass rate of the electrode assembly 22.

[0102] Optionally, as an embodiment, one end of the first electrode 31 along the second direction Y includes a pole tab 222, and a length L11 of the first edge notch 3131 close to the pole tab 222 along the second direction Y is less than a length L12 of the first edge notch 3131 away from the pole tab 222 along the second direction Y. Specifically, as shown in Figures 6 to 9, the length of the first edge notch 3131 close to the pole tab 222 along the second direction Y is L11, while the length of the first edge notch 3131 away from the pole tab 222 along the second direction Y is L12.

[0103] Optionally, as an embodiment, the ratio of the distance D2 between the first edge notch 3131 and the end of the corresponding first pole piece 31 along the second direction Y to the length D1 of the first pole piece 31 along the second direction Y is in the range of [0.008, 0.02]. This value range is obtained through a large number of experimental verifications. Specifically, as shown in Figures 6 to 9, if the multiple first notches 313 include multiple first edge notches 3131, then the distance D2 between the first edge notch 3131 and the end of the corresponding first pole piece 31 along the second direction Y in the embodiment of the present application may refer to the average value, minimum value or maximum value of the distances between the multiple first edge notches 3131 and the end of the corresponding first pole piece 31 along the second direction Y. For example, as shown in Figure 9, taking the multiple first notches 313 including two first edge notches 3131 as an example, the distance between the upper first edge notch 3131 and the upper edge of the first pole piece 31 along the second direction Y is D21, and the distance between the lower first edge notch 3131 and the lower edge of the first pole piece 31 along the second direction Y is D22. Then, in an embodiment of the present application, the distance D2 between the first edge notch 3131 and one end of the corresponding first pole piece 31 along the second direction Y can be the minimum value between D21 and D22, but the embodiment of the present application is not limited to this.

[0104] If the ratio of distance D2 to length D1 is too small, for example, less than 0.008, the distance D2 between the first edge notch 3131 and the corresponding edge of the first electrode piece 31 along the second direction Y will be too small. This will, on the one hand, lead to insufficient strength in the area between the first edge notch 3131 and the edge of the first electrode piece 31, thereby reducing the structural strength of the first electrode piece 31 and affecting the processing efficiency and performance of the electrode assembly 22. On the other hand, it will increase the processing accuracy requirements for the corresponding first edge notch 3131, increase the processing difficulty, and be detrimental to the processing efficiency of the electrode assembly 22. Therefore, the ratio of distance D2 to length D1 should not be too small.

[0105] On the contrary, if the ratio between the distance D2 and the length D1 is too large, for example, greater than 0.02, the distance D2 between the first edge notch 3131 and the corresponding edge of the first electrode piece 31 along the second direction Y will be relatively large, which will affect the effect of the first edge notch 3131 in reducing the bending resistance of the edge of the first electrode piece 31, and will not effectively reduce the bending difficulty of the electrode assembly 22, which is not conducive to the processing efficiency of the electrode assembly 22. Therefore, the ratio between the distance D2 and the length D1 should not be too large.

[0106] Optionally, the ratio between the distance D2 and the length D1 can be set according to actual application. For example, the ratio between the distance D2 and the length D1 can be set to 0.008, 0.009, 0.01, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019 or 0.02.

[0107] In addition, the distance D2 between the first edge notch 3131 and the corresponding end of the first pole piece 31 along the second direction Y in the embodiment of the present application can also be set according to the actual application. For example, the distance D2 can be set to a value range of [1mm, 30mm]. This value range is obtained through a large number of experimental verifications, so that the distance D2 is not too large or too small. For another example, the distance D2 can be set to 1mm, 3mm, 5mm, 8mm, 10mm, 13mm, 15mm, 18mm, 20mm, 23mm, 25mm, 28mm or 30mm.

[0108] The length D1 of the first pole piece 31 along the second direction Y of the embodiment of the present application can also be set according to actual application. For example, the value range of the length D1 can be set to [50mm, 1200mm], which is obtained through a large number of experimental verifications. For another example, the length D1 can be set to 50mm, 100mm, 150mm, 200mm, 250mm, 300mm, 350mm, 400mm, 450mm, 500mm, 550mm, 600mm, 650mm, 700mm, 750mm, 800mm, 850mm, 900mm, 950mm, 1000mm, 1100mm or 1200mm.

[0109] Optionally, as an embodiment, the distance D3 between a first edge score 3131 and an adjacent first intermediate score 3132 is in the range of [1 mm, 10 mm]. This range is verified through extensive experimentation. Specifically, as shown in Figures 6 to 9, if the plurality of first scores 313 includes a plurality of first edge scores 3131, the distance D3 between a first edge score 3131 and an adjacent first intermediate score 3132 in the embodiment of the present application may refer to the maximum value, minimum value, or average value of the distances between each first edge score 3131 and the corresponding first intermediate score 3132 in the plurality of first edge scores 3131. For example, as shown in Figure 9, taking the multiple first notches 313 including two first edge notches 3131 as an example, the distance between the upper first edge notch 3131 and an adjacent first middle notch 3132 along the second direction Y is D31, and the distance between the lower first edge notch 3131 and an adjacent first middle notch 3132 along the second direction Y is D32. Then, the distance D3 between the first edge notch 3131 and the adjacent first middle notch 3132 in the embodiment of the present application can be the minimum value between D31 and D32, but the embodiment of the present application is not limited to this.

[0110] If distance D3 is too large, that is, the distance between the first edge notch 3131 and the first intermediate notch 3132 is large, the area between the first edge notch 3131 and the adjacent first intermediate notch 3132 will still experience significant resistance during bending, failing to effectively reduce the resistance of the electrode assembly 22 during bending and hindering the processing efficiency of the electrode assembly 22. Therefore, distance D3 should not be set too large. Conversely, if distance D3 is too small, that is, the distance between the first edge notch 3131 and the first intermediate notch 3132 is small, the structural strength of the area between the first edge notch 3131 and the first intermediate notch 3132 will be too low, affecting the structural strength of the first electrode sheet 31 and, consequently, the electrode assembly 22. Furthermore, the machining precision requirements for the first edge notch 3131 and the adjacent first intermediate notch 3132 are high, increasing the machining difficulty of the electrode assembly 22 and, in turn, affecting the machining efficiency of the electrode assembly 22. Therefore, distance D3 should not be set too small.

[0111] Optionally, the specific value of the distance D3 can be set according to actual application. For example, the distance D3 can be specifically set to 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm or 10mm.

[0112] In the embodiment of the present application, the structure of the first notch 313 can be flexibly configured according to the actual application. For example, as shown in Figures 6 to 9, the first notch 313 is a through hole, which not only facilitates processing, but also greatly reduces resistance during the bending process, thereby improving the processing efficiency of the electrode assembly 22.

[0113] For another example, the first notch 313 is a groove, which can reduce resistance during the bending process and also reduce the loss of structural strength of the first electrode piece 31 of the electrode assembly 22 .

[0114] Alternatively, if the first notch 313 is a groove, the groove can be implemented in a variety of ways. For example, the groove can be implemented by locally thinning the first electrode piece 31, whereby the thickness of the bottom wall of the groove is less than the thickness of the area of ​​the first electrode piece 31 excluding the groove. For another example, the opening direction of the groove can be flexibly set according to the actual application. For example, the opening of the groove can be oriented toward the center of the electrode assembly 22, or the opening can be oriented away from the center of the electrode assembly 22. The embodiments of the present application are not limited thereto.

[0115] Optionally, the first edge score 3131 and the first middle score 3132 included in the first score 313 of the embodiment of the present application can be of the same or different types. For example, the first edge score 3131 can be a through hole, while the first middle score 3132 can be a groove; or, the first edge score 3131 and the first middle score 3132 can both be through holes. The embodiment of the present application is not limited to this.

[0116] The above mainly describes the size of the first notch 313 of the embodiment of the present application with reference to the accompanying drawings. The following will describe in detail the first notches 313 of different types of electrode assemblies 22 with reference to the accompanying drawings.

[0117] In the embodiment of the present application, the first pole piece 31 includes a plurality of first bent sections 311 having different bending directions W. Specifically, the first pole piece 31 can be formed by a bending method as shown in FIG6 , and the first pole piece 31 includes a plurality of first bent sections 311 having different bending directions W. For example, the first pole piece 31 includes a first bent section 311 bent along a clockwise direction W1 and also includes a first bent section 311 bent along a counterclockwise direction W2. By bending in different directions, a stacked electrode assembly 22 is formed. This structure is simple and easy to implement.

[0118] Optionally, the plurality of first bending segments 311 include two first bending segments 311 with opposite bending directions W, and the first notches 313 provided on the two first bending segments 311 have the same size along the bending direction W. Specifically, as shown in FIG6 , taking any one of the plurality of first bending segments 311 that bends along the clockwise direction W1 as an example, the size of the first bending segment 311 along the clockwise direction W1 is R1; and taking any one of the plurality of first bending segments 311 that bends along the counterclockwise direction W2 as an example, the size of the first bending segment 311 along the counterclockwise direction W2 is R2, and the size R1 can be set equal to R2, so that the forces on the plurality of first bending segments 311 that bend along different bending directions W are more uniform, the formed electrode assembly 22 is more uniform, the offset between different first stacked segments 312 is reduced, and the processing rate and qualified rate of the electrode assembly 22 are improved.

[0119] In the embodiment of the present application, the first electrode piece 31 includes a plurality of first bending segments 311 , and the plurality of first bending segments 311 have the same bending direction W, that is, the first electrode piece 31 is always bent along the same bending direction W. For example, as shown in FIG7 or FIG8 , the plurality of first bending segments 311 included in the first electrode piece 31 are all bent along the clockwise direction W1, thereby forming a wound electrode assembly 22 .

[0120] Optionally, the size of the first notch 313 provided in the first bend segment 311 near the center of the electrode assembly 22 among the multiple first bend segments 311 along the bending direction W is smaller than the size of the first notch 313 provided in the first bend segment 311 away from the center of the electrode assembly 22 along the bending direction W. For example, as shown in FIG7 , taking the right half of the first electrode sheet 31 as an example, the first electrode sheet 31 includes three first bend segments 311 in a direction from near the center of the electrode assembly 22 toward away from the electrode assembly 22, and each first bend segment 311 is provided with a first notch 313. From the inner first bend segment 311 toward the outer first bend segment 311, the sizes of the first notches 313 in the bending direction W of the three bend segments 311 are R11, R12, and R13, respectively. The sizes of the first notches 313 in the three first bend segments 311 along the bending direction W satisfy the following: R11<R12<R13.

[0121] Considering that the arc length of the first bending section 311 located inside the electrode assembly 22 along the bending direction W is smaller, that is, the bending radius is smaller, while the arc length of the first bending section 311 located outside the electrode assembly 22 along the bending direction W is larger, that is, the bending radius is larger, that is, the arc length of the first bending section 311 along the bending direction W gradually increases from the inside to the outside of the electrode assembly 22, then correspondingly, the size of the first notch 313 set in the first bending section 311 close to the center of the electrode assembly 22 among the multiple first bending sections 311 along the bending direction W is smaller than the size of the first notch 313 set in the first bending section 311 away from the center of the electrode assembly 22 along the bending direction W. This can make the size of the first notch 313 of the first bending section 311 with a smaller arc length also smaller, and the size of the first notch 313 of the first bending section 311 with a larger arc length also larger. On the one hand, it is convenient for processing, and on the other hand, it can also improve the structural strength of the electrode assembly 22 and reduce the problem of low local strength of the electrode assembly 22.

[0122] In the embodiment of the present application, the electrode assembly 22 further includes: a plurality of second electrode sheets 32 having opposite polarity to the first electrode sheet 31, and the plurality of second electrode sheets 32 and the plurality of first stacked sections 312 are alternately stacked along the first direction X. Specifically, as shown in FIG6 or FIG7 , although the processing method of the first electrode sheet 31 is different, the electrode assembly 22 may include a plurality of second electrode sheets 32, and the plurality of second electrode sheets 32 may be stacked and arranged between the plurality of first stacked sections 312. In this way, in the process of bending the electrode assembly 22, there is no need to bend the second electrode sheets 32, which reduces the number of bending layers and reduces the difficulty of bending the electrode assembly 22.

[0123] Optionally, along the third direction Z, the first bend section 311 corresponds to at least one second pole piece 32; along the first direction X, the size L3 of the first notch 313 is less than or equal to the size L4 of the corresponding at least one second pole piece 32, and the third direction Z is perpendicular to the first direction X and the second direction Y. For example, taking the first notch 313 provided on any one of the first bend sections 311 in FIG. 6 as an example, the size of the first notch 313 along the first direction X is L3; if a second pole piece 32 is provided corresponding to the first bend section 311 along the third direction Z, and the size of the second pole piece 32 along the first direction X is L4, then the size L3 is less than or equal to L4. Alternatively, if multiple layers of second pole pieces 32 are provided corresponding to the first bend section 311 along the third direction Z, then the size L3 is less than or equal to the total size of the multiple layers of second pole pieces 32 along the first direction X.

[0124] By setting the dimension L3 of the first notch 313 along the first direction X to be smaller than or equal to the dimension L4 of the corresponding at least one second electrode plate 32 along the first direction X, the phenomenon of active material precipitation caused by the first notch 313 being too large can be reduced, and the impact on the performance of the electrode assembly 22 can also be reduced.

[0125] In the embodiment of the present application, the electrode assembly 22 can also be formed by winding in other ways. For example, the electrode assembly 22 also includes: a second electrode piece 32 having a polarity opposite to that of the first electrode piece 31, and the first electrode piece 31 and the second electrode piece 32 are wound around a winding axis. Specifically, as shown in Figure 8, the first electrode piece 31 and the second electrode piece 32 can be wound to form the electrode assembly 22. In this way, the process of repeatedly cutting the second electrode piece 32 before winding can be reduced, thereby speeding up the winding process.

[0126] It should be understood that the second pole piece 32 of the embodiment of the present application can be similar to the first pole piece 31, and multiple notches can be provided on the second pole piece 32. Specifically, the second pole piece 32 includes multiple second stacked sections 322 and at least one second bent section 321, where the second bent section 321 is used to connect two adjacent second stacked sections 322. The multiple second stacked sections 322 are stacked along the first direction X, and the second pole piece 32 is configured to bend at the second bent section 321.

[0127] Furthermore, the second bend section 321 includes a plurality of second notches 323 arranged along the second direction Y. The plurality of second notches 323 include second edge notches located at both ends of the second pole piece 32 along the second direction Y and a second middle notch located in the middle region of the first pole piece 31. The length of the second edge notches along the second direction Y is greater than the length of the second middle notch along the second direction Y. Specifically, the plurality of second notches 323 provided on the second bend section 321 of the second pole piece 32 in the embodiment of the present application are similar to the plurality of first notches 313 provided on the first bend section 311 of the first pole piece 31. The description of the first notches 313 is applicable to the same and will not be repeated here for the sake of brevity.

[0128] In the embodiment of the present application, the second bending section 321 includes a plurality of second notches 323 arranged along the second direction Y. On the one hand, these plurality of second notches 323 can achieve positioning of the second bending section 321, reduce the offset of the second electrode sheet 32 ​​at the bend, and thereby reduce the offset between different electrode sheets of the electrode assembly 22. On the other hand, these plurality of second notches 323 can also reduce the difficulty of bending, reduce the resistance during bending, and thereby improve the processing efficiency of the electrode assembly 22. In addition, considering that when the second bending section 321 bends, the resistance at the two end edges of the second electrode sheet 32 ​​along the second direction Y is greater than the resistance at the middle of the second electrode sheet 32, and the fold fluctuation at the edge of the second electrode sheet 32 ​​is greater, by setting the length of the second edge notches along the second direction Y to be greater than the length of the second middle notches along the second direction Y, the resistance at the edge of the second electrode sheet 32 ​​can be further reduced, the fluctuation is reduced, and the probability of the second electrode sheet 32 ​​offset during bending is further reduced. This can also reduce the possibility of active material precipitation or electrode assembly 22 failure, thereby improving the processing efficiency and yield of the electrode assembly 22.

[0129] In the embodiment of the present application, the size of the notch provided on the bend section near the center of the electrode assembly among the multiple first bend sections 311 and at least one second bend section 321 along the bending direction W is smaller than the size of the notch provided on the bend section away from the center of the electrode assembly along the bending direction W. Specifically, taking the left half of the electrode assembly 22 shown in FIG8 as an example, in the radially outward direction from the center of the electrode assembly 22, the first pole piece 31 and the second pole piece 32 include a total of two first bend sections 311 and one second bend section 321, and the sizes of the notches provided on the three bend sections along the bending direction W are R21, R22, and R23, respectively. The sizes of the notches provided on the three bend sections along the bending direction W satisfy the following: R21<R22<R23.

[0130] Similarly, for the right half of the electrode assembly 22, in the radial outward direction from the center of the electrode assembly 22, the first pole piece 31 and the second pole piece 32 include a total of three first bending sections 311 and two second bending sections 321, and the size of the notches set on the five bending sections along the bending direction W also gradually increases along the radial direction from the inside to the outside of the electrode assembly 22.

[0131] Since the arc lengths of the first bending section 311 of the first pole piece 31 and the second bending section 321 of the second pole piece 32 gradually increase along the radial direction from the inside to the outside of the electrode assembly 22, that is, the bending radius gradually increases, then the corresponding sizes of the first notch 313 and the second notch 323 along the bending direction W also gradually increase along the radial direction from the inside to the outside of the electrode assembly 22, so that the size of the notch set in the bending section with a smaller arc length can also be smaller, and the size of the notch set in the bending section with a larger arc length can also be larger. On the one hand, it is convenient for processing, and on the other hand, it can also improve the structural strength of the electrode assembly 22 and reduce the trust of the local strength of the electrode assembly 22 being too low.

[0132] It should be understood that the polarities of the first electrode piece 31 and the second electrode piece 32 in the embodiments of the present application can be the same or opposite. For example, in the above-mentioned embodiments of the present application, the first electrode piece 31 is mainly used as a negative electrode piece, which can reduce the problem of active material precipitation and the impact on the performance of the electrode assembly 22. For another example, in the above-mentioned embodiments of the present application, the second electrode piece 32 is mainly used as a positive electrode piece, which can reduce the problem of active material precipitation and the impact on the performance of the electrode assembly 22.

[0133] FIG10 shows a schematic cross-sectional view of the first electrode piece 31 of an embodiment of the present application. For example, FIG10 may be a cross-sectional view of the first electrode piece 31 along the AA' direction shown in FIG9 , and here, the first electrode piece 31 is taken as an example of a negative electrode piece. FIG11 shows a schematic cross-sectional view of the second electrode piece 32 of an embodiment of the present application. The direction of the cross section is consistent with the direction shown in FIG10 , and here, the second electrode piece 32 is taken as an example of a positive electrode piece.

[0134] Optionally, the negative electrode sheet includes a negative current collector 314, and the surface of the negative current collector 314 is not coated with negative active material. In this way, the overall thickness of the negative electrode sheet is reduced, resulting in a lighter and smaller electrode assembly 22. Alternatively, while the overall thickness of the negative electrode sheet can be reduced, the thickness of the positive electrode sheet can be increased. For example, the thickness of the positive active material layer 325 of the positive electrode sheet can be increased, thereby increasing the energy density of the battery cell 20 including the electrode assembly 22.

[0135] Optionally, if the surface of the negative electrode current collector 314 is not coated with a negative electrode active material, the negative electrode current collector 314 may be made of copper foil, or conductive carbon may be coated on the surface of the copper foil. The embodiment of the present application is not limited thereto.

[0136] As shown in Figures 10 and 11, the positive electrode sheet of the embodiment of the present application may include a positive electrode current collector 324 and a positive electrode active material layer 325 respectively arranged on both sides of the positive electrode current collector 324. Among them, the material of the positive electrode active material layer 325 of the embodiment of the present application can be flexibly set according to the actual application. For example, the material of the positive electrode active material layer 325 includes at least one of the following: Prussian blue-based sodium ion positive electrode material, layered oxide sodium ion positive electrode material and polyanion sodium electrode material. The electrode assembly 22 and battery cell 20 formed by using such a positive electrode active material layer 325 have better high temperature resistance, reducing the possibility of the battery cell 20 exploding at high temperature.

[0137] Optionally, the electrode assembly 22 of the embodiment of the present application may further include a separator 33, which may be located between the first electrode piece 31 and the second electrode piece 32. For example, the separator 33 may be located between the positive electrode piece and the negative electrode piece to separate the positive electrode piece from the negative electrode piece. The material of the separator 33 of the embodiment of the present application can be set according to the actual application. For example, the material of the separator 33 may be an aluminum oxide ceramic coating and a polyvinylidene difluoride (PVDF) adhesive, but the embodiment of the present application is not limited to this.

[0138] Therefore, the electrode assembly 22 of the embodiment of the present application includes a first electrode piece 31, which includes a plurality of first stacked sections 312 and at least one bent section 311. The plurality of first stacked sections 312 are stacked along a first direction X, and the first direction X is perpendicular to the first stacked sections 312. The first bent section 311 is used to connect two first stacked sections 312, and the first electrode piece 31 can be bent at the first bent section 311. The first bent section 311 includes a plurality of first notches 313 arranged along a second direction Y, and the second direction Y is the extension direction of the first bent section 311. On the one hand, the first bent section 311 can be positioned by the plurality of first notches 313, reducing the offset of the first electrode piece 31 at the bend. On the other hand, the plurality of first notches 313 can also reduce the difficulty of bending, reduce the resistance during bending, and thereby improve the processing efficiency of the electrode assembly 22.

[0139] In addition, the plurality of first notches 313 include first edge notches 3131 located at both ends of the first electrode sheet 31 along the second direction Y, and a first middle notch 3132 located in the middle region of the first electrode sheet 31. Furthermore, the length of the first edge notch 3131 along the second direction Y is greater than the length of the first middle notch 3132 along the second direction Y. Considering that when the first bending section 311 is bent, the resistance at the two end edges of the first electrode sheet 31 along the second direction Y is greater than the resistance at the middle portion of the first electrode sheet 31, and the fold fluctuation at the edge of the first electrode sheet 31 is greater, by setting the length of the first edge notch 3131 along the second direction Y to be greater than the length of the first middle notch 3132 along the second direction Y, the resistance at the edge of the first electrode sheet 31 can be further reduced, the fluctuation can be reduced, and the probability of the first electrode sheet 31 shifting during bending can be further reduced, thereby reducing the possibility of active material precipitation and improving the processing efficiency and yield of the electrode assembly 22.

[0140] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. An electrode assembly, wherein: include: A first pole piece (31), the first pole piece (31) comprising a plurality of first stacked sections (312) and at least one first bent section (311), the plurality of first stacked sections (312) being stacked along a first direction, the first bent section (311) being used to connect two first stacked sections (312), the first pole piece (31) being configured to be bent at the first bent section (311), and the first direction being perpendicular to the first stacked sections (312); The first bending section (311) comprises a plurality of first notches (313) arranged along a second direction, the second direction being the extension direction of the first bending section (311), the plurality of first notches (313) comprising first edge notches (3131) located at both ends of the first pole piece (31) along the second direction and a first middle notch (3132) located in a middle area of ​​the first pole piece (31), the length of the first edge notch (3131) along the second direction being greater than the length of the first middle notch (3132) along the second direction.

2. The electrode assembly according to claim 1, wherein: Along the first direction, the plurality of first notches (313) are located in the middle of the first bending section (311).

3. The electrode assembly according to claim 1 or 2, wherein: The length of the first edge notch (3131) along the second direction is greater than or equal to three times the length of the first middle notch (3132) along the second direction; and / or, The length of the first edge score (3131) along the second direction is less than or equal to five times the length of the first middle score (3132) along the second direction.

4. The electrode assembly according to any one of claims 1 to 3, wherein: The plurality of first notches (313) include a plurality of first intermediate notches (3132), The lengths of the plurality of first intermediate notches (3132) along the second direction are equal, and / or the intervals between the plurality of first intermediate notches (3132) along the second direction are equal.

5. The electrode assembly according to any one of claims 1 to 4, wherein: One end of the first pole piece (31) along the second direction comprises a pole ear (222), and a length of a first edge notch (3131) close to the pole ear (222) along the second direction is shorter than a length of a first edge notch (3131) away from the pole ear (222) along the second direction.

6. The electrode assembly according to any one of claims 1 to 5, wherein: The ratio of the distance between the first edge notch (3131) and the corresponding end of the first pole piece (31) along the second direction to the length of the first pole piece (31) along the second direction is in the range of [0.008, 0.02].

7. The electrode assembly according to any one of claims 1 to 6, wherein: The distance between the first edge notch (3131) and the adjacent first middle notch (3132) is in the range of [1 mm, 10 mm].

8. The electrode assembly according to any one of claims 1 to 7, wherein: The first notch (313) is a through hole; or, The first notch (313) is a groove.

9. The electrode assembly according to any one of claims 1 to 8, wherein: The first pole piece (31) comprises a plurality of first bending sections (311) having different bending directions.

10. The electrode assembly according to claim 9, wherein: The plurality of first bending sections (311) include two first bending sections (311) with opposite bending directions, and the first notches (313) provided on the two first bending sections (311) have equal sizes along the bending direction.

11. The electrode assembly according to any one of claims 1 to 8, wherein: The first pole piece (31) comprises a plurality of the first bending sections (311), and the plurality of the first bending sections (311) have the same bending direction; The size of a first notch (313) arranged in a first bending section (311) close to the center of the electrode assembly among the plurality of first bending sections (311) along the bending direction is smaller than the size of a first notch (313) arranged in a first bending section (311) far from the center of the electrode assembly along the bending direction.

12. The electrode assembly according to any one of claims 9 to 11, wherein: The electrode assembly further comprises: A plurality of second pole pieces (32) having opposite polarities to the first pole piece (31), wherein the plurality of second pole pieces (32) and the plurality of first stacking sections (312) are alternately stacked along the first direction.

13. The electrode assembly according to claim 12, wherein: Along the third direction, the first bending section (311) corresponds to at least one second pole piece (32), Along the first direction, the size of the first notch (313) is smaller than or equal to the size of the corresponding at least one second pole piece (32), and the third direction is perpendicular to the first direction and the second direction.

14. The electrode assembly according to any one of claims 1 to 8 and 11, wherein: The electrode assembly further comprises: A second pole piece (32) having a polarity opposite to that of the first pole piece (31), wherein the first pole piece (31) and the second pole piece (32) are wound around a winding axis.

15. The electrode assembly according to claim 14, wherein: The second pole piece (32) comprises a plurality of second stacked sections (322) and at least one second bent section (321), wherein the second bent section (321) is used to connect two adjacent second stacked sections (322). The second bending section (321) comprises a plurality of second notches (323) arranged along the second direction, the plurality of second notches (323) comprising second edge notches located at both ends of the second pole piece (32) along the second direction and a second middle notch located in the middle area of ​​the first pole piece (31), the length of the second edge notch along the second direction being greater than the length of the second middle notch along the second direction.

16. The electrode assembly according to claim 15, wherein: The size of the notch arranged in the bending section close to the center of the electrode assembly among the plurality of first bending sections (311) and at least one of the second bending sections (321) along the bending direction is smaller than the size of the notch arranged in the bending section far from the center of the electrode assembly along the bending direction.

17. The electrode assembly according to any one of claims 12 to 16, wherein: The second pole piece (32) is a positive pole piece.

18. The electrode assembly according to claim 17, wherein: The positive electrode plate comprises a positive electrode active material layer (325), and the material of the positive electrode active material layer (325) comprises at least one of the following: a Prussian blue type sodium ion positive electrode material, a layered oxide sodium ion positive electrode material, and a polyanion sodium electrode material.

19. The electrode assembly according to any one of claims 1 to 18, wherein: The first pole piece (31) is a negative pole piece.

20. The electrode assembly according to claim 19, wherein: The negative electrode plate comprises a negative electrode current collector (314), and the surface of the negative electrode current collector (314) is not coated with negative electrode active material.

21. A battery cell, wherein: include: The electrode assembly according to any one of claims 1 to 20.

22. A battery, wherein: include: A plurality of battery cells, each of which comprises the electrode assembly according to any one of claims 1 to 20.

23. An electrical device, wherein: include: A battery, comprising the electrode assembly as claimed in any one of claims 1 to 20, wherein the battery is used to provide electrical energy to the electrical device.

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