Pole piece, electrode assembly, battery cell, battery, and electric device

Abstract

A pole piece (30), an electrode assembly (22), a battery monomer (20), a battery (10), an electric device and a method for manufacturing the electrode assembly (22). The pole piece (30) comprises: a laminated section (31) and a bending section (32), the bending section (32) is connected with the laminated section (31), and the bending section (32) is used for bending; wherein, a reinforcing structure (33) is arranged on a region of the laminated section (31) close to the bending section (32).

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrode sheet, electrode assembly, battery cell, battery, electrical device, and method of manufacturing electrode assembly. Background Technology

[0002] With the continuous advancement of battery technology, various new energy industries using batteries as energy storage devices have experienced rapid development. To improve the energy density of individual battery cells, the electrode sheets are typically designed to be quite thin. However, such electrodes are prone to misalignment during bending, which can affect the processing yield of the electrode assembly and potentially impact its performance, thereby leading to safety accidents. Summary of the Invention

[0003] This application provides an electrode sheet, an electrode assembly, a battery cell, a battery, an electrical device, and a method for manufacturing an electrode assembly, which can improve the processing efficiency of the electrode assembly.

[0004] In a first aspect, an electrode sheet is provided, comprising: a laminated section and a bent section, the bent section being connected to the laminated section and the bent section being used for bending; wherein, a reinforcing structure is provided in the region of the laminated section near the bent section.

[0005] Therefore, in the electrode of this application embodiment, by providing a reinforcing structure in the region near the bending section of the laminated section, the strength of the region near the bending section of the laminated section can be increased. Since the strength of this region near the bending section is relatively high, the position of the bending section can be positioned by the reinforcing structure. During the process of bending the electrode to form an electrode assembly, the bending position of the electrode can be restricted, causing the electrode to bend at the bending section, reducing bending misalignment of the electrode, and also reducing wrinkles in the region near the bending section of the laminated section. This improves the processing accuracy of the electrode assembly, thereby improving the processing yield and performance of the electrode assembly. For example, it can reduce lithium plating caused by electrode misalignment or wrinkles, thereby improving the reliability of the electrode assembly.

[0006] In some embodiments, the reinforcing structure includes a protrusion extending beyond the surface of the laminated segment. This reinforcing structure, achieved through the protrusion, is simple to implement and easy to manufacture; furthermore, the formation of the protrusion can be flexibly configured according to the specific application, facilitating processing.

[0007] In some embodiments, the ratio of the protrusion height of the protrusion structure to the thickness of the laminate segment ranges from [0.3, 50], optionally [5, 40], and preferably [8, 20].

[0008] Considering the requirements for energy density and performance within a single battery cell, the thickness of the laminated section has a limited range. If the ratio of the protrusion height to the thickness of the laminated section is set too small, the protrusion height will be too small, meaning the added strength from the protrusion structure will be too little. The strength of this reinforcing structure will be very similar to that of other areas within the laminated section, potentially failing to effectively restrict and position the bending section. Conversely, if the ratio of the protrusion height to the thickness of the laminated section is set too large, the protrusion height will be excessive. This will increase the distance between multiple electrode layers after the electrode is processed into an electrode assembly, reducing the space utilization rate of the electrode assembly within the battery cell and thus lowering the battery cell's energy density. Furthermore, if the protrusion structure is formed by stamping, an excessively high stamped protrusion can easily cause damage or even breakage of the electrode at the stamping point, affecting the processing efficiency and yield of the electrode and electrode assembly.

[0009] In some embodiments, the protrusion protrudes relative to the first surface of the laminated segment and is recessed relative to the second surface of the laminated segment. The first surface and the second surface are disposed opposite to each other. This protrusion structure is simple to process and easy to implement, and does not require additional structures, thus not increasing the weight of the electrode too much.

[0010] In some embodiments, the protrusion structure includes a reinforcing sheet disposed on the surface of the laminated segment. Depending on actual needs, a suitable material can be selected to process the reinforcing sheet, thereby obtaining a reinforcing structure with a specific strength, making the implementation more flexible and effective.

[0011] In some embodiments, the ratio of the stiffness of the reinforcing structure to the stiffness of other regions of the laminated segment (excluding the reinforcing structure) ranges from [1.5, 65], optionally [2, 40], and preferably [10, 25]. If the ratio of the stiffness of the reinforcing structure to the stiffness of other regions of the laminated segment is too small, since the stiffness of the reinforcing structure is greater than that of other regions of the laminated segment, the strength difference between the reinforcing structure and other regions of the laminated segment will be very small, and the reinforcing structure may not be able to effectively restrict and position the bending segment. Conversely, if the ratio of the stiffness of the reinforcing structure to the stiffness of other regions of the laminated segment is too large, due to the limitations of the structure and materials of the laminated segment itself, the strength requirement for the reinforcing structure will be too high, increasing the difficulty of processing and material selection, and also increasing costs.

[0012] In some embodiments, the stiffness of the reinforcing structure ranges from [10 N / m, 300 N / m], preferably [50 N / m, 150 N / m]. Since the stiffness of the reinforcing structure should be greater than the stiffness of other regions of the laminated section, the stiffness value of the reinforcing structure should not be too small, so that the reinforcing structure can effectively restrict and position the bending section. Conversely, if the stiffness of the reinforcing structure is set too high, the strength requirement for the reinforcing structure will be too high, increasing the difficulty of processing and material selection, and also increasing costs.

[0013] In some embodiments, the reinforcing structure does not pass through the centerline of the laminated section along the length of the electrode, and the ratio of the span of the reinforcing structure along the length of the electrode to the length of the laminated section ranges from [10%, 50%]. Since the reinforcing structure does not pass through the centerline of the laminated section along the length of the electrode, the ratio of the span of the reinforcing structure along the length of the electrode to the length of the laminated section will be less than 50%. Conversely, the ratio of the span of the reinforcing structure along the length of the electrode to the length of the laminated section should not be set too small; a sufficiently large span of the reinforcing structure can improve its reinforcing effect.

[0014] In some embodiments, the ratio of the span of the reinforcing structure along the length of the electrode to the length of the laminated segment ranges from [10%, 100%]. This ratio should not be set too small; for example, it can typically be set to be greater than or equal to 10% to ensure that the span of the reinforcing structure is large enough to improve its reinforcing effect.

[0015] In some embodiments, the ratio of the sum of the widths of all the reinforcing structures arranged along the width direction of the electrode to the width of the electrode ranges from [1 / 3, 0.8], preferably [0.4, 0.6]. If this ratio is set too small, most areas along the width direction of the electrode will not have the reinforcing structure. When the electrode is bent, misalignment is likely to occur in this area, which will affect the processing yield of the electrode assembly and may also affect the performance of the electrode assembly. Conversely, if this ratio is set too large, the reinforcing structure will occupy too much area, which may also affect the strength of this area. Especially when the reinforcing structure is set by stamping, if the reinforcing structure is distributed too much along the width direction of the electrode, it may not be able to effectively strengthen the structural strength of the laminated section near the bending section, which will cause misalignment to still occur when the electrode is bent, thus affecting the processing yield of the electrode assembly and may also affect the performance of the electrode assembly.

[0016] In some embodiments, the ratio of the shortest length between the end of the reinforcing structure near the bending section and the centerline of the bending section to the thickness of the electrode sheet ranges from [0.016, 0.5], preferably [0.05, 0.4]. If this ratio is too small, since the electrode sheet is usually thin, the reinforcing structure will be too close to the centerline of the bending section. When the electrode sheet is bent, the range of the bending section restricted by the reinforcing structure will be too small, making the electrode sheet difficult to bend and increasing the processing difficulty of the electrode assembly. Conversely, if this ratio is too large, the reinforcing structure will be too far from the centerline of the bending section, making it difficult for the reinforcing structure to restrict the bending section. The electrode sheet will still be prone to misalignment when bent, thus affecting the processing efficiency and yield of the electrode assembly.

[0017] In some embodiments, the reinforcing structure is inclined relative to the width direction of the electrode to provide a reinforcing effect in the direction perpendicular to the width of the electrode, thereby limiting the position where the electrode bends.

[0018] In some embodiments, the angle between the reinforcing structure and the width direction of the electrode is in the range of [45°, 135°]. If the angle is set too large or too small, the reinforcing effect of the reinforcing structure in the direction perpendicular to the width of the electrode will be much smaller than that in the direction parallel to the width of the electrode, which will reduce the bending resistance and misalignment prevention effect of the reinforcing structure.

[0019] In some embodiments, the region of the laminated section near the bending section is provided with a plurality of reinforcing structures arranged along the width direction of the electrode, which can increase the structural strength of different regions in the width direction of the electrode and reduce the possibility of local misalignment when the electrode is bent along the bending area.

[0020] In some embodiments, a plurality of the reinforcing structures are arranged at equal intervals along the width direction of the electrode to facilitate processing, and the arrangement of the plurality of reinforcing structures can also be made more uniform to uniformly increase the structural strength of different regions in the width direction of the electrode.

[0021] In some embodiments, multiple reinforcing structures protrude from the surface of the stacked segment and protrude in the same direction. If multiple reinforcing structures arranged along the width direction of the electrode sheet protrude in the same direction, then the multiple reinforcing structures can occupy the space on the same side of the electrode sheet, reducing the gap between the multilayer structures of the electrode assembly, thereby improving the space utilization rate of the electrode assembly inside the battery cell, and thus improving the energy density of the battery cell.

[0022] In some embodiments, the electrode includes multiple laminated segments, and the bending segment connects a first laminated segment and a second laminated segment among the multiple laminated segments. The regions of the first laminated segment and the second laminated segment near the bending segment are respectively provided with reinforcing structures. The region between the reinforcing structures of the first and second laminated segments includes the bending segment. This means that the reinforcing structures of the first and second laminated segments can jointly constrain the position of the bending segment, thereby reducing misalignment, bending, and wrinkling of the first and second laminated segments when the electrode is bent. This allows for more accurate positioning of the bending segment, improving the processing efficiency and yield of the electrode assembly, and ultimately improving the performance of the battery cell.

[0023] In some embodiments, the reinforcing structure of the first laminate segment and the reinforcing structure of the second laminate segment are positioned correspondingly in the width direction of the electrode; and / or, the reinforcing structure of the first laminate segment and the reinforcing structure of the second laminate segment are positioned offset in the width direction of the electrode.

[0024] With the reinforcing structures of the first and second stacked sections positioned correspondingly along the width of the electrode, the reinforcing structures of the first and second stacked sections can essentially overlap when the electrode is bent along the bending section, resulting in a simple structure that is easy to manufacture. Alternatively, with the reinforcing structures of the first and second stacked sections misaligned, they cannot completely overlap when the electrode is bent along the bending section. This provides greater flexibility in positioning the reinforcing structures of the first and second stacked sections. When bending the electrode to form an electrode assembly, the space occupied by the reinforcing structures of the first and second stacked sections can be adjusted, making better use of the space between different electrode layers and improving the space utilization rate of the electrode assembly within the battery cell, thereby increasing the energy density of the battery cell.

[0025] In some embodiments, the reinforcing structures of the first and second stacked segments are arranged at equal intervals along the width of the electrode. This uniform arrangement of the reinforcing structures in the first and second stacked segments facilitates processing and ensures a uniform distribution of the reinforcing structures. It also reduces the risk of misalignment in different areas of the first and second stacked segments during electrode bending, thereby improving the processing efficiency and yield of the electrode assembly.

[0026] In some embodiments, the reinforcing structure of the first stacked segment includes a protrusion protruding from the surface of the first stacked segment, and the reinforcing structure of the second stacked segment includes a protrusion protruding from the surface of the second stacked segment, with the protrusion direction of the reinforcing structure of the first stacked segment opposite to that of the reinforcing structure of the second stacked segment. Thus, after the electrode is bent along the bending section, the first and second stacked segments are stacked, and the protrusion direction of the reinforcing structure of the first stacked segment is consistent with that of the reinforcing structure of the second stacked segment. When the reinforcing structure of the second stacked segment protrudes from one side of the second stacked segment and is recessed from the other side, the portion of the reinforcing structure of the first stacked segment protruding from the surface of the first stacked segment can be accommodated in the recessed area of ​​the reinforcing structure of the second stacked segment. This reduces the gap between different electrode layers, improves the space utilization of the electrode assembly within the battery cell, and ultimately increases the energy density of the battery cell.

[0027] In some embodiments, the bending section is provided with a notch extending along the width direction of the electrode sheet. On the one hand, the notch can be used to position the bending section, reduce the offset of the electrode sheet at the bend, and thus reduce the offset between different electrodes of the electrode assembly; on the other hand, the notch can also reduce the difficulty of bending, reduce the resistance during bending, and thus improve the processing efficiency of the electrode assembly.

[0028] In some embodiments, the number of the notches includes multiple notches, and the reinforcing structure corresponds to the connection area between two adjacent notches in the multiple notches, so that the reinforcing structure and the multiple notches cooperate with each other to jointly position and limit the position of the bending section, and improve the structural strength of the electrode in the area around the bending section. When the electrode is bent, misalignment or wrinkling in different areas along the width direction of the electrode is avoided as much as possible, thereby improving the processing efficiency and yield of the electrode assembly.

[0029] In some embodiments, the number of the grooves includes a plurality of edge grooves located at both ends of the electrode along the width direction of the electrode and a middle groove located in the middle region of the electrode, wherein the length of the edge grooves along the width direction of the electrode is greater than the length of the middle grooves along the width direction of the electrode.

[0030] Considering that the resistance at both ends of the electrode along the width direction is greater than that at the middle position when the electrode is bent, and the crease fluctuation at the edge position is greater, by setting the length of the edge crease along the width direction to be greater than that of the middle crease, the resistance at the edge position of the electrode can be reduced more significantly, the fluctuation can be reduced, and the probability of electrode deviation during bending can be further reduced. This can also reduce the possibility of active material precipitation or electrode assembly failure, and improve the processing efficiency and yield of the electrode assembly.

[0031] In some embodiments, the number of grooves includes multiple grooves, and the length of the multiple grooves is equal along the width direction of the electrode. By setting the multiple grooves arranged along the width direction to have equal dimensions along the width direction, the number of times the dimensions of the grooves need to be adjusted during processing can be reduced, the processing difficulty can be reduced, and the processing efficiency can be improved.

[0032] In some embodiments, the notch is located in the middle of the bending section along the length of the electrode, so that the electrode is positioned more accurately when bent along the notch, minimizing the misalignment and offset of the electrode, thereby improving the processing efficiency and yield of the electrode assembly.

[0033] In some embodiments, the electrode is a negative electrode without a negative electrode. This electrode is thinner, and when assembled into an electrode assembly and disposed within a battery cell, it can improve the space utilization of the electrode assembly, thereby increasing the energy density of the battery cell. Furthermore, because the electrode is thinner, it is more prone to misalignment or wrinkling when bent. The reinforcing structure effectively reduces misalignment and wrinkling, improving the processing efficiency and yield of the electrode assembly.

[0034] In a second aspect, an electrode assembly is provided, comprising: a first electrode, the first electrode being the electrode as described in the first aspect, the first electrode being configured to bend in the bending section.

[0035] In some embodiments, the reinforcing structure is an indentation on the surface of the laminated segment. During the bending of the first electrode, this reinforcing structure can be used to limit the position of the bent segment. Afterwards, the reinforcing structure, being an indentation on the surface of the laminated segment, does not occupy the gaps between different electrode layers of the electrode assembly, thus improving the space utilization of the electrode assembly within the battery cell and consequently increasing the energy density of the battery cell.

[0036] In some embodiments, the electrode assembly further includes a plurality of second electrodes with a polarity opposite to that of the first electrode, the plurality of second electrodes being alternately stacked with a plurality of the stacked segments along the thickness direction of the stacked segments. Thus, during the bending of the electrode assembly, there is no need to bend the second electrodes, reducing the number of bending layers and lowering the difficulty of bending the electrode assembly.

[0037] In some embodiments, the first electrode includes a plurality of bent segments, with the bending directions of the two bent segments at opposite ends of the same stacked segment being opposite. By bending in different directions, a stacked electrode assembly is formed, which is simple and easy to implement.

[0038] Thirdly, a battery cell is provided, comprising: the electrode assembly described in the second aspect.

[0039] Fourthly, a battery is provided, comprising a plurality of battery cells, each battery cell including the electrode assembly described in the second aspect.

[0040] Fifthly, an electrical device is provided, comprising: a battery cell as described in the third aspect, or a battery as described in the fourth aspect, wherein the battery cell or the battery is used to provide electrical energy to the electrical device.

[0041] In some embodiments, the electrical equipment is a vehicle, a ship, or a spacecraft.

[0042] A sixth aspect provides a method for manufacturing an electrode assembly, comprising: providing a first electrode sheet including a laminated section and a bent section, the bent section connecting the laminated section, a reinforcing structure being provided in a region of the laminated section near the bent section; and bending the first electrode sheet in the bent section.

[0043] Therefore, in the method for manufacturing an electrode assembly according to the embodiments of this application, during the process of bending the first electrode to form the electrode assembly, the bending position of the first electrode can be restricted by the reinforcing structure provided on the first electrode, so that the first electrode bends in the bending section, reducing the bending misalignment of the first electrode, and also reducing wrinkles in the area of ​​the laminated section near the bending section, improving the processing accuracy of the electrode assembly, and thus improving the processing pass rate and performance of the electrode assembly. For example, it can reduce the lithium plating phenomenon caused by the misalignment or wrinkles of the first electrode, thereby improving the reliability of the electrode assembly.

[0044] In some embodiments, the laminated segment is stamped along its thickness direction to form a raised structure on its surface, the reinforcing structure including the raised structure; the laminated segment is then extruded. When the first electrode is bent, the reinforcing structure formed by stamping can limit the bending position of the first electrode, causing it to bend at the bending section, reducing bending misalignment, and also reducing wrinkles in the region of the laminated segment near the bending section. For the formed electrode assembly, the size of the extruded reinforcing structure protruding from other areas of the laminated segment is reduced, and it can even be substantially flush with other areas of the laminated segment, thereby reducing the distance between the first and second electrodes, thus reducing the ion conduction path and improving the performance of the electrode assembly.

[0045] In some embodiments, the extrusion of the laminated segment includes: extruding the laminated segment by hot pressing. Due to the hot pressing process, the originally protruding reinforcing structure is flattened, which reduces the size of the reinforcing structure protruding from other areas of the laminated segment, or even makes it substantially flush with other areas of the laminated segment; furthermore, the hot pressing process can further reduce the distance between the first electrode and the second electrode, thereby reducing the ion conduction path and improving the space utilization rate of the electrode assembly inside the battery cell, thereby increasing the energy density of the battery cell. Attached Figure Description

[0046] Figure 1This is a schematic diagram of the structure of a vehicle disclosed in one embodiment of this application;

[0047] Figure 2 This is an exploded structural diagram of a battery disclosed in an embodiment of this application;

[0048] Figure 3 This is a schematic diagram of the structure of a battery comprising multiple battery cells disclosed in an embodiment of this application;

[0049] Figure 4 This is a schematic diagram of the structure of a battery cell disclosed in an embodiment of this application;

[0050] Figure 5 This is an exploded structural diagram of a battery cell disclosed in an embodiment of this application;

[0051] Figure 6 This is a schematic diagram of the structure of a first electrode sheet disclosed in an embodiment of this application;

[0052] Figure 7 This is a partial structural enlarged view of a first electrode sheet disclosed in an embodiment of this application;

[0053] Figure 8 This is a partial cross-sectional schematic diagram of a first electrode sheet disclosed in an embodiment of this application;

[0054] Figure 9 This is a partial cross-sectional schematic diagram of another first electrode sheet disclosed in an embodiment of this application;

[0055] Figure 10 This is a schematic diagram of the structure of a first electrode sheet disclosed in another embodiment of this application;

[0056] Figure 11 This is a schematic diagram of the structure of a first electrode sheet disclosed in another embodiment of this application;

[0057] Figure 12 This is a schematic diagram of the structure of a first electrode sheet disclosed in another embodiment of this application;

[0058] Figure 13 This is a partial structural enlarged view of a first electrode sheet disclosed in another embodiment of this application;

[0059] Figure 14 This is a partial structural schematic diagram of a first electrode sheet disclosed in another embodiment of this application;

[0060] Figure 15 This is a schematic diagram of the structure of an electrode assembly disclosed in an embodiment of this application;

[0061] Figure 16 This is a side view of an electrode assembly disclosed in an embodiment of this application;

[0062] Figure 17 This is a schematic diagram of another electrode assembly disclosed in an embodiment of this application;

[0063] Figure 18 This is a side view of another electrode assembly disclosed in an embodiment of this application;

[0064] Figure 19 This is a schematic flowchart of a method for manufacturing an electrode assembly disclosed in an embodiment of this application.

[0065] The accompanying drawings are not drawn to scale. Detailed Implementation

[0066] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0067] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation 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 orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0068] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0069] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0070] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0071] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0072] In some implementations, the battery cell in this application embodiment can be a metal battery. Specifically, the metal battery may include lithium metal secondary batteries, sodium metal batteries, or magnesium metal batteries, etc. This application embodiment does not limit this.

[0073] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0074] 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.

[0075] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0076] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0077] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0078] In some embodiments, the negative electrode may be a negative electrode sheet, which may include a negative electrode current collector. As an example, the positive electrode active material may include at least one of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds.

[0079] In some embodiments, the chemical formula of the sodium transition metal oxide can satisfy Na x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Zn, V, Zr, Ce, Cr and Cu, and 0 < x ≤ 1.

[0080] As an example, Na x In MO2, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1.

[0081] In some embodiments, the sodium transition metal oxide may be a doped sodium transition metal oxide, and the doping modification of the sodium transition metal oxide may include at least one of sodium site doping modification, oxygen site doping modification, transition metal site doping modification, and surface coating modification.

[0082] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal may also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0083] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0084] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0085] In some implementations, the battery cell in the embodiments of this application may be a sodium-free secondary battery.

[0086] A negative electrode-less sodium secondary battery refers to a battery in which no negative electrode active material layer is actively placed on the negative electrode side during the battery manufacturing process. For example, a sodium metal or carbonaceous active material layer is not formed at the negative electrode through coating or deposition processes. During the first charge, sodium ions gain electrons on the anode side and deposit metallic sodium on the current collector surface to form a sodium metal phase. During discharge, the metallic sodium can be converted back into sodium ions and return to the positive electrode, achieving cyclic charging and discharging. Compared to other sodium secondary batteries, a negative electrode-less sodium secondary battery can achieve a higher energy density due to the absence of a negative electrode active material layer.

[0087] In some implementations, to improve battery performance, functional coatings such as carbonaceous materials, metal oxides, and alloys can be applied to the negative electrode side of the negative electrode of the sodium-free secondary battery to improve the conductivity of the negative electrode current collector and the uniformity of the deposited sodium metal.

[0088] In some implementations, the CB value of a sodium-ion secondary battery without a negative electrode is less than or equal to 0.1.

[0089] Specifically, the CB value is the capacity per unit area of ​​the negative electrode in a secondary battery divided by the capacity per unit area of ​​the positive electrode. Since batteries without a negative electrode contain little or no functional coating, the capacity per unit area of ​​the negative electrode is relatively small, and the CB value of the secondary battery is less than or equal to 0.1.

[0090] In some embodiments, the negative electrode sheet may further include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0091] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0092] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc.

[0093] In some embodiments, the negative electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When foamed metal is used as the negative electrode sheet, the surface of the foamed metal may or may not have a negative electrode active material.

[0094] As an example, lithium source material, potassium metal or sodium metal may also be filled or deposited in the negative electrode current collector, wherein the lithium source material is lithium metal and / or lithium-rich material.

[0095] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0096] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0097] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0098] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride, and ceramic.

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

[0100] 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 impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0101] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0102] In some implementations, the electrode assembly is a stacked structure.

[0103] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0104] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0105] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0106] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0107] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0108] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0109] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0110] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc. The housing includes a shell and a cover plate.

[0111] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. This application does not have any particular limitations.

[0112] The battery mentioned in the embodiments of this application may be a single physical module comprising one or more battery cells to provide higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or mixed via a busbar.

[0113] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0114] In some embodiments, the battery can be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0115] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0116] The battery cell in this embodiment contains an electrode assembly. During the process of forming the electrode assembly by stacking or winding the electrodes, bending the electrodes may be necessary. However, since the electrodes are typically very thin, it is difficult to precisely control the specific bending area. Therefore, during the bending process, there is a possibility that the bending may not be done according to the predetermined dimensions, potentially leading to misalignment of the electrodes, such as misalignment or wrinkles. This affects the processing yield of the electrode assembly and may also affect its performance, for example, making the electrodes prone to lithium plating, which could lead to safety accidents.

[0117] Therefore, embodiments of this application provide an electrode sheet, an electrode assembly, a battery cell, a battery, an electrical device, and a method for manufacturing an electrode assembly, which can solve the above-mentioned problems. The electrode sheet in this application includes connected laminated sections and bending sections. The bending sections are used for bending, meaning the electrode sheet can be bent in these sections. A reinforcing structure is provided in the region of the laminated section near the bending section, which increases the strength of this region. Because the region of the laminated section near the bending section has high strength, the bending section can be positioned using the reinforcing structure. During the process of bending the electrode sheet to form an electrode assembly, the bending position of the electrode sheet can be restricted, causing the electrode sheet to bend in the bending section, reducing bending misalignment, and also reducing wrinkles in the region of the laminated section near the bending section. This improves the processing accuracy of the electrode assembly, thereby improving the processing yield and performance of the electrode assembly. For example, it can reduce lithium plating caused by electrode misalignment or wrinkles, thus improving the reliability of the electrode assembly.

[0118] The technical solutions described in the embodiments of this application are applicable to various battery-powered electrical devices.

[0119] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical equipment.

[0120] For ease of explanation, the following embodiments use a vehicle as an example of electrical equipment.

[0121] For example, such as Figure 1The diagram shown is a structural schematic of a vehicle 1 according to one embodiment of this application. Vehicle 1 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A motor 60, a controller 50, and a battery 10 can be installed inside vehicle 1. The controller 50 controls the battery 10 to supply power to the motor 60. For example, the battery 10 can be installed at the bottom, front, or rear of vehicle 1. The battery 10 can be used to power vehicle 1; for example, it can serve as the operating power source for the vehicle 1's electrical system, such as for the power requirements of starting, navigation, and operation. In another embodiment of this application, the battery 10 can not only serve as the operating power source for vehicle 1 but also as the driving power source, replacing or partially replacing gasoline or natural gas to provide driving power to vehicle 1.

[0122] To meet diverse power demands, a battery can comprise multiple individual cells, which can be connected in series, parallel, or a combination of both. A battery can also be called a battery pack. Optionally, multiple individual cells can first be connected in series, parallel, or a combination of both to form a battery module, and then multiple battery modules can be connected in series, parallel, or a combination of both to form a battery. In other words, multiple individual cells can be directly assembled into a battery, or they can first be assembled into battery modules, and then the battery modules can be assembled into a battery.

[0123] For example, Figure 2 The diagram shows a structural schematic of a battery 10 according to an embodiment of this application. The battery 10 may include a plurality of battery cells 20. Figure 3 A schematic diagram of the plurality of battery cells 20 included in the battery 10 is shown. (As shown) Figure 2 and Figure 3 As shown, the battery 10 may also include a housing 11, which has a hollow interior and houses multiple battery cells 20. Figure 2 This application illustrates one possible implementation of the housing 11, such as... Figure 2 As shown, the housing 11 may include two parts, referred to herein as a first part 111 and a second part 112, which are fastened 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 assembly, and at least one of the first part 111 and the second part 112 has an opening. For example, as... Figure 2 As shown, both the first part 111 and the second part 112 can be hollow cuboids and each has only one face as an opening. The openings of the first part 111 and 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 11 with a closed cavity.

[0124] For example, unlike Figure 2 As shown, in the first part 111 and the second part 112, only one can be a hollow cuboid with an opening, while the other can be plate-shaped to cover the opening. For example, if the second part 112 is a hollow cuboid with only one open face, and the first part 111 is plate-shaped, then the first part 111 covers the opening of the second part 112 to form a box 11 with a closed cavity, which can be used to accommodate multiple battery cells 20. The multiple battery cells 20 are connected in parallel, series, or mixed and placed inside the box 11 formed by the first part 111 and the second part 112.

[0125] Optionally, the battery 10 may also include other structures, which will not be described in detail here. For example, such as Figure 2 and Figure 3 As shown, the battery 10 may further include a busbar component 12, which is used to realize the electrical connection between multiple battery cells 20, such as in parallel, series, or mixed connection. Specifically, the busbar component 12 can realize the electrical connection between battery cells 20 by connecting the electrode terminals 214 of the battery cells 20. Further, the busbar component 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 housing 11 via a conductive mechanism.

[0126] Depending on different power demands, the number of battery cells 20 in battery 10 can be set to any value. Multiple battery cells 20 can be connected in series, parallel, or mixed connections to achieve a larger capacity or power. Since each battery 10 may contain 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 unlimited and can be set according to requirements.

[0127] Figure 4 This is a schematic diagram of the structure of a battery cell 20 according to one embodiment of this application. Figure 5 This is a partially exploded structural diagram of a battery cell 20 according to an embodiment of this application. For example, Figure 5 The battery cell 20 shown can be Figures 2 to 4 Any one of the battery cells is 20. For example... Figure 4 and Figure 5 As shown, for ease of explanation, a rectangular battery cell 20 is used as an example. In the figure, direction Z represents the height direction of battery cell 20, direction X represents the width direction or thickness direction of battery cell 20, and direction Y represents the length direction of battery cell 20. Furthermore, the height direction Z, width direction Z, and length direction Y of battery cell 20 are perpendicular to each other.

[0128] like Figure 4and Figure 5 As shown, the battery cell 20 in this embodiment may include: a housing 21. Specifically, the housing 21 may include: a shell 211, which is 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 housing 21.

[0129] It should be understood that the housing 211 in this embodiment is a component for accommodating the electrode assembly 22. The housing 211 can be a hollow structure with an opening at one or more ends. For example, if the housing 211 is a hollow structure with an opening at one end, a cover plate 212 can be provided as one; if the housing 211 is a hollow structure with openings at opposite ends, two cover plates 212 can be provided, with the two cover plates 212 respectively covering the openings at both ends of the housing 211.

[0130] The shell 211 can be of various shapes, such as a cylinder, a cuboid, or other polyhedrons. For example, ... Figure 4 and Figure 5 As shown in the embodiments of this application, the shell 211 is mainly described as a cuboid structure with an opening at one end.

[0131] It should be understood that the cover plate 212 in this 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, such as... Figure 4 and Figure 5 As shown, the shell 211 has a cuboid structure, and the cover plate 212 has a rectangular plate structure that is adapted to the shell 211.

[0132] In this embodiment, the shell 211 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. The cover plate 212 can also be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. Optionally, the material of the cover plate 212 can be the same as or different from the material of the shell 211.

[0133] It should be understood that the battery cell 20 also includes electrode terminals 214. In this embodiment, the electrode terminals 214 are used for electrical connection with the electrode assembly 22 inside the battery cell 20 to output the electrical energy of the battery cell 20. Figures 4 to 5As shown, the battery cell 20 may include at least two electrode terminals 214, which may include at least one positive electrode terminal 214a and at least one negative electrode terminal 214b. The positive electrode terminal 214a is used for electrical connection to the positive electrode tab 222a of the electrode assembly 22, and the negative electrode terminal 214b is used for electrical connection to the negative electrode tab 222b of the electrode assembly 22. The positive electrode terminal 214a and the positive electrode tab 222a may be directly connected or indirectly connected, and the negative electrode terminal 214b and the negative electrode tab 222b may be directly connected or indirectly connected. For example, the positive electrode terminal 214a may be electrically connected to the positive electrode tab 222a through a connecting member, and the negative electrode terminal 214b may be electrically connected to the negative electrode tab 222b through a connecting member.

[0134] In this battery cell 20, the electrode assembly 22 is the component in which the electrochemical reaction occurs. Depending on actual usage requirements, the electrode assembly 22 within the casing 211 can be one or multiple. For example, as... Figure 4 and Figure 5 As shown, two electrode assemblies 22 are provided inside the battery cell 20. The electrode assembly 22 can be a cylinder, a cuboid, etc. If the electrode assembly 22 is a cylindrical structure, the housing 211 can also be a cylindrical structure. If the electrode assembly 22 is a cuboid structure, the housing 211 can also be a cuboid structure.

[0135] It should be understood that, such as Figure 4 and Figure 5 As shown, the electrode assembly 22 includes tabs 222 and an electrode body 221. The tabs 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 a positive 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 a negative active material layer. The electrode body 221 may be formed by stacking or winding the positive electrode sheet and the negative electrode sheet together.

[0136] Figure 6 A partial structural schematic diagram of the electrode 30 according to an embodiment of this application is shown, and Figure 6 The image shows the unfolded state of the electrode 30, for example, the... Figure 6 This can be the state of the electrode 30 before it is wound or stacked to form the electrode assembly 22. Figure 7 This diagram shows a partial enlarged structural schematic of an electrode 30 according to an embodiment of this application. For example, the... Figure 7 It can be Figure 6 An enlarged view of region A shown. Figure 8 and Figure 9These are schematic cross-sectional views of a partial region of the electrode 30 according to one embodiment of this application, for example, Figure 8 and Figure 9 They can be respectively as follows Figure 6 An enlarged view of a possible cross-section of region C of electrode 30 along the B-B' direction.

[0137] like Figures 6 to 9 As shown, the electrode 30 in this embodiment includes a laminated section 31 and a bent section 32, the bent section 32 being connected to the laminated section 31 and used for bending; wherein, a reinforcing structure 33 is provided in the region of the laminated section 31 near the bent section 32.

[0138] The electrode 30 in this embodiment can be any electrode used to form the electrode assembly 22. For example, the electrode 30 can be a positive electrode or a negative electrode. For ease of distinction, the electrode 30 will be referred to as the first electrode 30 below, that is, the first electrode 30 can be any electrode included in the electrode assembly 22.

[0139] The first electrode 30 in this embodiment includes interconnected stacked segments 31 and bent segments 32. During the assembly of the first electrode 30 into the electrode assembly 22, the first electrode 30 can be bent at the bent segment 32 to allow the multiple stacked segments 31 to be stacked or wound together, thereby forming the electrode assembly 22. For ease of explanation, this embodiment will first be described using the first electrode 30 in an unbent state to form the electrode assembly 22 as an example.

[0140] In this embodiment, a reinforcing structure 33 is provided in the region of the laminated section 31 of the first electrode 30 near the bending section 32, which increases the structural strength of the region of the laminated section 31 near the bending section 32. Since the region of the laminated section 31 near the bending section 32 has greater strength, the reinforcing structure 33 can be used to position the bending section 32. During the bending of the first electrode 30 to form the electrode assembly 22, the bending position of the first electrode 30 can be restricted, causing the first electrode 30 to bend at the bending section 32, reducing bending misalignment of the first electrode 30, and also reducing wrinkles in the region of the laminated section 31 near the bending section 32. This improves the processing accuracy of the electrode assembly 22, thereby improving the processing yield and performance of the electrode assembly 22. For example, it can reduce lithium plating caused by misalignment or wrinkles of the first electrode 30, thus improving the reliability of the electrode assembly 22.

[0141] It should be understood that the reinforcing structure 33 in the embodiments of this application can be implemented in a variety of ways.

[0142] In some embodiments, the reinforcing structure 33 can be achieved by using different materials, that is, the material of the region where the reinforcing structure 33 is located in the laminated segment 31 is different from the material of other regions of the laminated segment 31, thereby improving the structural strength of the reinforcing structure 33.

[0143] In some embodiments, the reinforcing structure 33 includes a protrusion extending beyond the surface of the laminated segment 31. Implementing the reinforcing structure 33 with a protrusion makes it easier to achieve, and the formation method of the protrusion can be customized according to the specific application to facilitate processing.

[0144] For example, the protruding structure protrudes from the first surface 311 of the laminated section 31, and is recessed from the second surface 312 of the laminated section 31. The first surface 311 and the second surface 312 are arranged opposite to each other. This protruding structure is simple to process, easy to implement, and does not require additional structures, thus not significantly increasing the weight of the first electrode 30. Figure 8 As shown, a protruding structure can be formed in the region of the laminated section 31 of the first electrode 31 near the bending section 32 by means of stamping or rolling to serve as a reinforcing structure 33. In this way, the protruding structure protrudes relative to the first surface 311 of the laminated section 31 and is recessed relative to the second surface 312 opposite to the first surface 311. That is, the reinforcing structure 33 forms a groove structure 333 on the second surface 312 of the laminated section 31.

[0145] It should be understood that the protruding structure protruding relative to the first surface 311 means that the protruding structure is raised relative to the other areas of the first surface 311 except for the reinforcing structure 33; correspondingly, the protruding structure being recessed relative to the second surface 312 means that the protruding structure is recessed relative to the other areas of the second surface 312 except for the reinforcing structure 33. Since the first electrode 30 is usually a thin sheet structure, the first surface 311 and the second surface 312, which are arranged opposite to each other in this embodiment, are respectively surfaces perpendicular to the thickness direction T of the first electrode 30, that is, surfaces perpendicular to the thickness direction T of the laminated section 31.

[0146] For example, the protruding structure includes a reinforcing sheet disposed on the surface of the laminated segment 31. Specifically, a reinforcing sheet may be disposed on at least one surface of the laminated segment 31, for example, as shown in the figure. Figure 9As shown, a reinforcing sheet can be provided on the first surface 311 of the laminated segment 31. Depending on actual needs, a suitable material can be selected to process the reinforcing sheet, resulting in a reinforced structure 33 of a specific strength, making the implementation more flexible and effective. For example, the material of the reinforcing sheet can be selected according to the actual application. For instance, the material of the reinforcing sheet includes, but is not limited to, at least one of the following: polymer plastics, non-woven fabrics, carbon fibers, and cardboard. In some embodiments, the reinforcing sheet can be fixed to the laminated segment 31 by adhesive bonding, or it can be fixed by welding or other methods.

[0147] like Figures 6 to 9 As shown, regardless of the method used to implement the protruding structure, the protrusion height T2 of the protruding structure relative to the stacked segment 31 in this embodiment can be flexibly set according to actual applications. For example, a suitable protrusion height T2 can be set according to the thickness T1 of the stacked segment 31. In this embodiment, the thickness T1 of the stacked segment 31 refers to the thickness of the area of ​​the stacked segment 31 excluding the reinforcing structure 33, specifically the average thickness of the area of ​​the stacked segment 31 excluding the reinforcing structure 33. The protrusion height T2 of the protruding structure relative to the stacked segment 31 in this embodiment refers to the distance between the surface of the protruding structure and the surface of the stacked segment 31. For example, taking the protruding structure protruding from the first surface 311 of the stacked segment 31 as an example, the protrusion height T2 is the distance between the surface of the protruding structure furthest from the first surface 311 and the first surface 311, for example, it can be the maximum distance or the average distance between the two surfaces.

[0148] For example, the ratio of the protrusion height T2 of the protrusion structure to the thickness T1 of the stacked section 31 ranges from [0.3, 50], optionally [5, 40], and preferably [8, 20]. Considering the requirements of energy density and performance inside the battery cell 20, the range of the thickness T1 of the stacked section 31 is limited. If the ratio of the protrusion height T2 to the thickness T1 of the stacked section 31 is set too small, for example less than 0.3, then the protrusion height T2 will be too small, that is, the strength increased by the protrusion structure will also be too small. The strength of the reinforcing structure 33 will be very small compared with the strength of other areas of the stacked section 31, and it may not be able to restrict and position the bending section 32. Conversely, if the ratio of the protrusion height T2 to the thickness T1 of the stacked segment 31 is set too large, for example, exceeding 50, then the protrusion height T2 will be too large. On the one hand, this will increase the distance between the multiple layers of electrodes after the first electrode 30 is processed into the electrode assembly 22, thereby reducing the space utilization rate of the electrode assembly 22 inside the battery cell 20, and thus reducing the energy density of the battery cell 20. On the other hand, if the protrusion structure is formed by stamping, then if the height T2 of the stamped protrusion structure is too high, it is easy for the first electrode 30 to be damaged or even broken at the stamping point. For example, the material of the first electrode 30 may include graphite, and the graphite-coated first electrode 30 is easy to break during the stamping process, thereby affecting the processing efficiency and yield of the first electrode 30 and the electrode assembly 22.

[0149] Therefore, the ratio of the protrusion height T2 to the thickness T1 of the stacked segment 31 in this embodiment should not be set too large or too small. For example, the ratio of the protrusion height T2 to the thickness T1 of the stacked segment 31 can be set to be greater than or equal to 0.3, further, greater than or equal to 0.5, to effectively improve the structural strength of the reinforcing structure 33. Further, it can be greater than or equal to 8, so that the reinforcing effect of the reinforcing structure 33 is better. For another example, the ratio of the protrusion height T2 to the thickness T1 of the stacked segment 31 can be set to be less than or equal to 50, further, less than or equal to 40, to reduce damage or breakage of the first electrode 30; further, it can be less than or equal to 20, to improve the space utilization rate of the electrode assembly 22 using the first electrode 30 inside the battery cell 20, thereby improving the energy density of the battery cell 20. For example, the ratio of the protrusion height T2 to the thickness T1 of the stacked segment 31 can be set to 0.3, 0.8, 1, 3, 5, 8, 10, 13, 15, 18, 20, 23, 25, 28, 30, 33, 35, 38, 40, 43, 45, 48 or 50, but the embodiments of this application are not limited to this.

[0150] For example, the thickness T1 of the laminated segment 31 in this embodiment can be flexibly set according to actual application. For instance, the thickness T1 of the laminated segment 31 can be equal to the thickness of the bent segment 32, that is, the thickness of the area of ​​the first electrode 30 other than the reinforcing structure 33 can be uniform, then the thickness T1 of the laminated segment 31 is the thickness T1 of the first electrode 30. As another example, the value range of the thickness T1 of the laminated segment 31 can be [6μm, 300μm]. As yet another example, the thickness T1 of the laminated segment 31 can specifically be 6μm, 10μm, 30μm, 50μm, 80μm, 100μm, 130μm, 150μm, 180μm, 200μm, 230μm, 250μm, or 300μm.

[0151] For example, the protrusion height T2 of the protrusion structure relative to the stacked segment 31 in this embodiment can be flexibly set according to actual applications. For instance, the protrusion structure can be a structure with uniform thickness, that is, the protrusion height of different regions of the protrusion structure relative to the stacked segment 31 is the same, so as to facilitate processing. As another example, the value range of the protrusion height T2 of the protrusion structure relative to the stacked segment 31 can be [0.1mm, 0.8mm], and further, [0.1mm, 0.4mm]. As yet another example, the protrusion height T2 of the protrusion structure relative to the stacked segment 31 can specifically be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, or 0.8mm.

[0152] It should be understood that the strength of the reinforcing structure 33 in this embodiment can be set according to actual application. For example, the strength of the reinforcing structure 33 can be represented by its stiffness value.

[0153] In some embodiments, the ratio of the stiffness of the reinforcing structure 33 to the stiffness of other regions of the laminated segment 31, excluding the reinforcing structure 33, ranges from [1.5, 65], optionally [2, 40], and preferably [10, 25]. If the ratio of the stiffness of the reinforcing structure 33 to the stiffness of other regions of the laminated segment 31 is too small, for example, less than 1.5, since the stiffness of the reinforcing structure 33 is greater than the stiffness of other regions of the laminated segment 31, the strength difference between the reinforcing structure 33 and the strength of other regions of the laminated segment 31 will be very small, and the reinforcing structure 33 may not be able to effectively restrict and position the bending segment 32. Conversely, if the ratio of the stiffness of the reinforcing structure 33 to the stiffness of other regions of the laminated segment 31 is too large, for example, greater than 65, due to the limitations of the structure and material of the laminated segment 31 itself, the strength requirement for the reinforcing structure 33 will be too high, which will increase the difficulty of processing and material selection, and also increase costs.

[0154] Therefore, the ratio of the stiffness of the reinforcing structure 33 to the stiffness of other regions of the laminated segment 31 in this embodiment should not be too large or too small. For example, the ratio of their stiffnesses can be set to be greater than or equal to 1.5, further, greater than or equal to 2, to improve the strength of the reinforcing structure 33, and even further, greater than or equal to 10, so that the strength of the reinforcing structure 33 meets the design requirements. For another example, the ratio of their stiffnesses can also be set to be less than or equal to 65, further, less than or equal to 40, to reduce the processing difficulty of the reinforcing structure 33, and even further, less than or equal to 25, so that the reinforcing structure 33 is easier to implement. For example, the ratio of the stiffness of the reinforcing structure 33 to the stiffness of other regions of the laminated segment 31 can be set to 1.5, 2, 5, 8, 10, 13, 15, 18, 20, 23, 25, 28, 30, 33, 35, 38, 40, 43, 45, 48, 50, 53, 55, 58, 60, 63 or 65, but the embodiments of this application are not limited to this.

[0155] It should be understood that the stiffness of the reinforcing structure 33 in this embodiment can be flexibly set according to actual application. For example, the stiffness of the reinforcing structure 33 can range from [10 N / m, 300 N / m], preferably [50 N / m, 150 N / m]. Since the stiffness of the reinforcing structure 33 should be greater than the stiffness of other areas of the laminated segment 31, the stiffness of the reinforcing structure 33 should not be too small, for example, it should generally not be less than 10 N / m, so that the reinforcing structure 33 can effectively restrict and position the bending segment 32. Conversely, if the stiffness of the reinforcing structure 33 is set too large, for example, greater than 300 N / m, the strength requirement for the reinforcing structure 33 will be too high, which will increase the difficulty of processing and material selection of the reinforcing structure, and also increase the cost.

[0156] Therefore, the stiffness of the reinforcing structure 33 should not be too large or too small. For example, the stiffness of the reinforcing structure 33 can be set to be greater than or equal to 10 N / m, and further, greater than or equal to 50 N / m, so that the reinforcing structure 33 can effectively restrict and position the bending segment 32. As another example, the stiffness of the reinforcing structure 33 can be set to be less than or equal to 300 N / m, and further, less than or equal to 150 N / m, to reduce the processing difficulty and cost of the reinforcing structure 33. For yet another example, the stiffness of the reinforcing structure 33 can be specifically set to 10 N / m, 30 N / m, 50 N / m, 80 N / m, 100 N / m, 130 N / m, 150 N / m, 180 N / m, 200 N / m, 230 N / m, 250 N / m, 280 N / m, or 300 N / m, but the embodiments of this application are not limited to these.

[0157] It should be understood that the stiffness of different structures in the embodiments of this application can be obtained through experimental testing. For example, taking the stiffness of the reinforcing structure 33 as an example, it can be obtained through the following test, but the embodiments of this application are not limited to this. First, take a first pole piece 30 of a certain size, such that this part of the first pole piece 30 includes at least a portion of the reinforcing structure 33. For example, a first pole piece 30 with a length of approximately 30 mm can be taken, and the width direction W needs to include the width of at least one complete reinforcing structure 33. For example, it can include only the width of one reinforcing structure 33. Second, fix this part of the first pole piece 30 on a high-precision balance, such that after fixing, the reinforcing structure 33 included in this part of the first pole piece 30 extends at least 20 mm beyond the fixed position along the length direction L. For example, this part of the first pole piece 30 can be fixed on the top of a 2cm*2cm cube on the high-precision balance, and except for the 2cm*2cm fixed area, the reinforcing structure 33 of this part of the first pole piece 30 extends at least 20 mm beyond the length direction L. Next, a 1mm steel needle is used to press down vertically on the top of the protruding part of the reinforcing structure 33 of the first pole piece 30 until the top is pressed down by 5mm. The balance reading at this time is recorded as A(N). The stiffness value of the reinforcing structure 33 tested is equal to A / deformation, that is, A / 0.005. The unit of this stiffness value is n / m.

[0158] In this embodiment, the region of the laminated section 31 near the bending section 32 is provided with a plurality of reinforcing structures 33 arranged along the width direction W of the first electrode 30. This can increase the structural strength of different regions in the width direction W of the first electrode 30, thereby reducing the possibility of local misalignment when the first electrode 30 is bent along the bending region 32.

[0159] It should be understood that the position and size of the plurality of reinforcing structures 33 arranged along the width direction W of the first electrode 30 in the embodiments of this application can be set according to actual applications.

[0160] In some embodiments, the plurality of reinforcing structures 33 are arranged at equal intervals along the width direction W of the first electrode 30. Specifically, as Figures 6 to 9 As shown, take a plurality of reinforcing structures 33 spaced apart along the width direction W of the first electrode 30 as an example. Here, the distance between the first reinforcing structure 33 and the second reinforcing structure 33 is denoted as W3, and the distance between the second reinforcing structure 33 and the third reinforcing structure 33 is denoted as W4. W3 and W4 can be equal or unequal. For example, W3 can be set to be equal to W4, and so on. The distance between any two adjacent reinforcing structures 33 in the plurality of reinforcing structures spaced apart along the width direction W of the first electrode 30 is set to be equal to W3, which facilitates processing and makes the plurality of reinforcing structures 33 more uniformly arranged, so as to uniformly increase the structural strength of different regions along the width direction W of the first electrode 30.

[0161] In some embodiments, the widths of the plurality of reinforcing structures 33 arranged at intervals in the width direction W of the first electrode 30 are equal. Specifically, as Figures 6 to 9 As shown, the width of each of the multiple reinforcing structures 33 arranged at intervals in the width direction W of the first electrode 30 is equal to W2. This facilitates processing and makes the arrangement of the multiple reinforcing structures 33 more uniform, resulting in a more uniform distribution of structural strength.

[0162] In some embodiments, the plurality of reinforcing structures 33 protrude from the surface of the stacked segment 31 and protrude in the same direction. When the plurality of reinforcing structures 33 protrude from other areas of the stacked segment 31, the reinforcing structures 33 will occupy the space between different electrode layers of the electrode assembly 22 formed by the first electrode 30. If the plurality of reinforcing structures 33 arranged along the width direction W of the first electrode 30 protrude in the same direction, the plurality of reinforcing structures 33 can occupy the space on the same side of the first electrode 30, reduce the gap between the multilayer structures of the electrode assembly 22, thereby improving the space utilization rate of the electrode assembly 22 inside the battery cell 20, and thus improving the energy density of the battery cell 20.

[0163] In this embodiment, the width of the reinforcing structure 33 can be flexibly set according to actual application. For example, the ratio of the sum of the widths of all reinforcing structures 33 arranged along the width direction W of the first electrode 30 to the width W1 of the first electrode 30 ranges from [1 / 3, 0.8], preferably [0.4, 0.6]. Specifically, if multiple reinforcing structures 33 are arranged along the width direction W of the first electrode 30, and the widths of these multiple reinforcing structures 33 are equal, then the sum of the widths of all reinforcing structures 33 arranged along the width direction W of the first electrode 30 is equal to the width of each reinforcing structure 33 multiplied by the number of reinforcing structures 33. For example, as... Figures 6 to 9 As shown, if eight reinforcing structures 33 are arranged along the width direction W of the first electrode 30, and the width of each of the multiple reinforcing structures 33 is W2, then the sum of the widths of all the reinforcing structures 33 arranged along the width direction W of the first electrode 30 is equal to 8*W2.

[0164] If the ratio of the sum of the widths of all the reinforcing structures 33 arranged along the width direction W of the first electrode 30 to the width W1 of the first electrode 30 in this embodiment is set too small, for example less than 1 / 3, then most areas along the width direction W of the first electrode 30 will not have the reinforcing structure 33. When the first electrode 30 is bent, it is easy for misalignment to occur in this part of the area, which will affect the processing qualification rate of the electrode assembly 22 and may also affect the performance of the electrode assembly 22. Conversely, if the ratio of the sum of the widths of all reinforcing structures 33 arranged along the width direction W of the first electrode 30 to the width W1 of the first electrode 30 is set too large, for example, greater than 0.8, then the reinforcing structure 33 occupies too much area, which may also affect the strength of this part of the area. Especially when the reinforcing structure 33 is set by stamping, if the reinforcing structure 33 is distributed too much along the width direction W of the first electrode 33, it may not be able to strengthen the structural strength of the laminated section 31 near the bending section 32, thus causing the first electrode 30 to still be misaligned when bent, thereby affecting the processing qualification rate of the electrode assembly 22 and may also affect the performance of the electrode assembly 22.

[0165] Therefore, the ratio of the sum of the widths of all the reinforcing structures 33 arranged along the width direction W of the first electrode 30 to the width W1 of the first electrode 30 should not be too large or too small. For example, this ratio can be set to be greater than or equal to 1 / 3, and further, greater than or equal to 0.4, to reduce the risk of local misalignment of the first electrode 30. Alternatively, this ratio can be set to be less than or equal to 0.8, and further, less than or equal to 0.6, to improve the effectiveness of the reinforcing structure 33. For further examples, this ratio can be specifically set to 1 / 3, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, or 0.8.

[0166] In this embodiment, for any reinforcing structure 33, the ratio of the width W2 of the reinforcing structure 33 along the width direction W of the first electrode 30 to the width W1 of the first electrode 30 can also be set according to the actual application. For example, the ratio of the width W2 of the reinforcing structure 33 to the width W1 of the first electrode 30 should not be too small. Since the width W1 of the first electrode 30 is limited, setting the ratio too small will greatly increase the processing difficulty of the reinforcing structure 33 and also reduce the strength of the reinforcing structure 33. Therefore, the ratio of the width W2 of the reinforcing structure 33 to the width W1 of the first electrode 30 is usually set to be greater than or equal to 0.0025, and further, it can be set to be greater than or equal to 0.01.

[0167] In the embodiments of this application, such as Figures 6 to 9As shown, the ratio of the shortest length L3 between the end of the reinforcing structure 33 near the bending section 32 and the centerline Lb of the bending section 32 to the thickness T1 of the first electrode 30 ranges from [0.016, 0.5], preferably [0.05, 0.4]. Specifically, in this embodiment, the centerline Lb of the bending section 32 is perpendicular to the length direction L of the first electrode 30 and is located in the middle region of the bending section 32. The thickness T1 of the first electrode 30 in this embodiment can be equal to the thickness of the region of the laminated section 31 excluding the reinforcing structure 33, or it can be equal to the thickness of the bending section 32; this embodiment is not limited to this.

[0168] If the ratio of the shortest length L3 to the thickness T1 of the first electrode 30 is too small, since the thickness T1 of the first electrode 30 is usually thin, the reinforcing structure 33 will be too close to the centerline Lb of the bending section 32. When the first electrode 30 is bent, the range of the bending section 32 restricted by the reinforcing structure 33 will be too small, making it difficult to bend the first electrode 30 and increasing the processing difficulty of the electrode assembly 22. Furthermore, if a notch 34 is provided in the middle area of ​​the bending section 32, the reinforcing structure 33 will affect the area around the notch 34 of the bending section 32, increasing the processing difficulty of the notch 34. Conversely, if the ratio of the shortest length L3 to the thickness T1 of the first electrode 30 is too large, the reinforcing structure 33 will be too far from the centerline Lb of the bending section 32. The reinforcing structure 33 will be unable to effectively restrict the bending section 32, and the first electrode 30 will still be prone to misalignment when bent, thus affecting the processing efficiency and yield of the electrode assembly 22.

[0169] Therefore, the ratio of the shortest length L3 to the thickness T1 of the first electrode 30 should not be too large or too small. For example, the ratio of the shortest length L3 between the end of the reinforcing structure 33 near the bending section 32 and the centerline Lb of the bending section 32 to the thickness T1 of the first electrode 30 can be set to be greater than or equal to 0.016, and further, greater than or equal to 0.05, to increase the bending efficiency of the first electrode 30. Alternatively, the ratio of the shortest length L3 to the thickness T1 of the first electrode 30 can be set to be less than or equal to 0.5, and further, less than or equal to 0.4, to reduce the possibility that the first electrode 30 is still prone to misalignment during bending. For example, the ratio of the shortest length L3 to the thickness T1 of the first electrode 30 can be set to 0.016, 0.03, 0.05, 0.08, 0.1, 0.13, 0.15, 0.18, 0.2, 0.23, 0.25, 0.28, 0.3, 0.33, 0.35, 0.38, 0.4, 0.43, 0.45, 0.48, or 0.5.

[0170] In some embodiments, the shortest length L3 between the end of the reinforcing structure 33 near the bending section 32 and the centerline Lb of the bending section 32 can be set according to the actual application. For example, the value range of the shortest length L3 can be set to [0.5mm, 3mm], and further, the value range of the shortest length L3 can be set to [1mm, 2mm]. For yet another example, the shortest length L3 can be set to be equal to 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, or 3mm.

[0171] In some embodiments, when multiple reinforcing structures 33 are arranged in the width direction W of the first electrode 30, the shortest length between the end of the multiple reinforcing structures 33 near the bending section 32 and the center line Lb of the bending section 32 can be set to be equal or unequal. For example, they can be set to be equal so that the multiple reinforcing structures 33 are more evenly distributed in the width direction W of the first electrode 30, thereby improving the effect of the reinforcing structures 33.

[0172] In this embodiment, the dimensions of the reinforcing structure 33 along the length direction L of the first electrode 30 can be set according to actual application. For example, the reinforcing structure 33 does not pass through the centerline La of the laminated segment 31 along the length direction L of the first electrode 30, and the ratio of the span L2 of the reinforcing structure 33 along the length direction L of the first electrode 30 to the length L1 of the laminated segment 31 ranges from [10%, 50%]. Specifically, as shown... Figures 6 to 9 As shown, the centerline La of the laminated segment 31 along the length direction L of the first electrode 30 is perpendicular to the length direction L of the first electrode 30, and the center La of the laminated segment 31 is located in the middle region of the laminated segment 31. Since the two opposite ends of the laminated segment 31 along the length direction L of the first electrode 30 may be connected to bending segments 32, the two opposite ends of the laminated segment 31 along the length direction L of the first electrode 30 can be provided with reinforcing structures 33. Therefore, for the reinforcing structure 33 at the end of the laminated segment 31 near the bending segment 32, the reinforcing structure 33 can be configured not to pass through the centerline La of the laminated segment 31 along the length direction L of the first electrode 30, so as to avoid affecting the reinforcing structure 33 at the other end of the laminated segment 31.

[0173] Since the reinforcing structure 33 does not pass through the centerline La of the laminated section 31 along the length L of the first electrode 30, the ratio of the span L2 of the reinforcing structure 33 along the length L of the first electrode 30 to the length L1 of the laminated section 31 will be less than 50%. The ratio of the span L2 of the reinforcing structure 33 along the length L of the first electrode 30 to the length L1 of the laminated section 31 should not be set too small either. For example, this ratio can usually be set to be greater than or equal to 10% so that the span L2 of the reinforcing structure 33 is large enough to improve the reinforcing effect of the reinforcing structure 33. For example, the ratio of the span L2 of the reinforcing structure 33 along the length L of the first electrode 30 to the length L1 of the laminated section 31 can usually be set to 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 48%.

[0174] Figure 10 A partial structural schematic diagram of the first electrode 30 according to another embodiment of this application is shown, and Figure 10 The diagram shows the unfolded state of the first pole piece 30, for example, the... Figure 10 This can be the state of the electrode 30 before it is wound or stacked to form the electrode assembly 22. For example... Figure 10 As shown, the reinforcing structure 33 can also adopt the following... Figure 10 The arrangement shown is as follows. Specifically, considering that the two ends of the laminated section 31 along the length direction L of the first electrode 30 may be connected to bending sections 32 respectively, if the areas of the laminated section 31 near the bending sections 32 at both ends are provided with reinforcing structures 33, then the reinforcing structure 33 can be set to pass through the centerline La of the laminated section 31 along the length direction L of the first electrode 30.

[0175] Correspondingly, such as Figures 6 to 10As shown, the ratio of the span L2 of the reinforcing structure 33 along the length L of the first electrode 30 to the length L1 of the laminated section 31 ranges from [10%, 100%]. Since the reinforcing structure 33 can pass through the centerline La of the laminated section 31 along the length L of the first electrode 30, the ratio of the span L2 of the reinforcing structure 33 along the length L of the first electrode 30 to the length L1 of the laminated section 31 can be less than or equal to 100%. The ratio of the span L2 of the reinforcing structure 33 along the length L of the first electrode 30 to the length L1 of the laminated section 31 should not be set too small. For example, the ratio can usually be set to be greater than or equal to 10% so that the span L2 of the reinforcing structure 33 is large enough to improve the reinforcing effect of the reinforcing structure 33. For example, the ratio of the span L2 of the reinforcing structure 33 along the length direction L of the first electrode 30 to the length L1 of the laminated segment 31 can typically be set to 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%.

[0176] In this embodiment, the reinforcing structure 33 is inclined relative to the width direction W of the first electrode 30. The reinforcing structure 33 in this embodiment is a strip structure, and its inclined arrangement relative to the width direction W of the first electrode 30 means that the extension direction of the reinforcing structure 33 is different from the width direction W of the first electrode 30, or in other words, the extension direction of the reinforcing structure 33 is not parallel to the width direction W of the first electrode 30.

[0177] If the reinforcing structure 33 is not tilted relative to the width direction W of the first electrode 30, it will be difficult for it to provide reinforcement. Therefore, when the first electrode 30 bends, the reinforcing structure 33 will also be less effective in limiting the position of the bent segment 32. Thus, the reinforcing structure 33 can be tilted relative to the width direction W of the first electrode 30 so that it provides reinforcement in the direction perpendicular to the width direction W of the first electrode 30, thereby limiting the bending position of the first electrode 30.

[0178] In some embodiments, the tilt angle of the reinforcing structure 33 relative to the width direction W of the first electrode 30 can be set according to the actual application. For example, the angle α between the reinforcing structure 33 and the width direction W of the first electrode 30 can be in the range of [45°, 135°]. If the angle α is set too large or too small, for example, less than 45° or greater than 135°, then the reinforcing effect of the reinforcing structure 33 in the width direction W perpendicular to the first electrode 30 is much smaller than that in the width direction W parallel to the first electrode 30, which will reduce the bending resistance and anti-misalignment effect of the reinforcing structure 33.

[0179] Therefore, the included angle α should not be set too large or too small. For example, the range of the included angle α can be [45°, 135°], further, it can also be [60°, 120°], and even further, the included angle α can be set to 90° to improve the effect of the reinforcing structure 33. The included angle α can be set to 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 110°, 115°, 120°, 125°, 130° or 135°.

[0180] In this embodiment, the first electrode 30 includes multiple laminated segments 31, and a bending segment 32 connects the first laminated segment 313 and the second laminated segment 314 among the multiple laminated segments 31. Reinforcing structures 33 are respectively provided in the regions of the first laminated segment 313 near the bending segment 32 and in the regions of the second laminated segment 314 near the bending segment 32. Specifically, as... Figures 6 to 10 As shown, the bending section 32 is connected to two stacked sections 314, so that when the first electrode 30 is bent in the bending section 32, the two stacked sections 31 can be stacked along the thickness direction T of the stacked section 31 to form the electrode assembly 22. Reinforcing structures 33 are provided in the regions of the first stacked segment 313 and the second stacked segment 314 near the bending segment 32. The region between the reinforcing structure 331 of the first stacked segment 313 and the reinforcing structure 332 of the second stacked segment 314 includes the bending segment 32. That is, the reinforcing structure 331 of the first stacked segment 313 and the reinforcing structure 332 of the second stacked segment 314 can jointly restrict the position of the bending segment 32, so as to reduce the misalignment, bending and wrinkling of the first stacked segment 313 and the second stacked segment 314 when the first electrode 30 is bent, and more accurately position the bending segment 32, thereby improving the processing efficiency and yield of the electrode assembly 22, and thus improving the performance of the battery cell 20.

[0181] It should be understood that the reinforcing structure 331 provided in the first stacked segment 313 is applicable to all the descriptions above regarding the reinforcing structure 33 provided in the stacked segment 33; similarly, the reinforcing structure 332 provided in the second stacked segment 314 is also applicable to all the descriptions above regarding the reinforcing structure 33 provided in the stacked segment 33. For the sake of brevity, these will not be elaborated upon here.

[0182] Furthermore, the reinforcing structure 331 provided near the bending section 32 in the first stacked segment 313 of this application embodiment can have the same or different parameters as the reinforcing structure 332 provided near the bending section 32 in the second stacked segment 314. For example, the reinforcing structure 331 of the first stacked segment 313 can have the same size and shape as the reinforcing structure 332 of the second stacked segment 314 to facilitate processing.

[0183] For example, the reinforcing structure 331 of the first laminated segment 313 and the reinforcing structure 332 of the second laminated segment 314 are positioned correspondingly in the width direction W of the first electrode 30. Specifically, as... Figures 6 to 9 As shown, the reinforcing structure 331 of the first laminated segment 313 and the reinforcing structure 332 of the second laminated segment 314 are positioned correspondingly in the width direction W of the first electrode 30. That is, the position of the reinforcing structure 331 of the first laminated segment 313 and the reinforcing structure 332 of the second laminated segment 314 are basically symmetrical with respect to the bending segment 32. In this way, when the first electrode 30 is bent along the bending segment 32, the reinforcing structure 331 of the first laminated segment 313 and the reinforcing structure 332 of the second laminated segment 314 can basically overlap, resulting in a simple structure that is easy to process.

[0184] For example, the reinforcing structure 331 of the first laminated segment 313 and the reinforcing structure 332 of the second laminated segment 314 are misaligned in the width direction W of the first electrode 30. Specifically, Figure 11 A partial structural schematic diagram of the first electrode 30 according to another embodiment of this application is shown, and Figure 11 The diagram shows the unfolded state of the first pole piece 30, for example, the... Figure 11 This can be the state of the first electrode 30 before it is wound or stacked to form the electrode assembly 22. It differs from... Figure 6 The reinforcement structure 33 shown is configured as follows: Figure 10 and Figure 11 As shown, the reinforcing structure 331 of the first laminated segment 313 and the reinforcing structure 332 of the second laminated segment 314 can be staggered. That is, the position of the reinforcing structure 331 of the first laminated segment 313 and the reinforcing structure 332 of the second laminated segment 314 are asymmetrical with respect to the bending segment 32. Furthermore, when the first electrode 30 is bent along the bending segment 32, the reinforcing structure 331 of the first laminated segment 313 and the reinforcing structure 332 of the second laminated segment 314 cannot completely overlap. For example, it can be as follows: Figure 10 The areas shown overlap partially and do not overlap partially, or can be as follows: Figure 11 As shown, all layers do not overlap. This allows for more flexible positioning of the reinforcing structures 331 of the first stacked segment 313 and 332 of the second stacked segment 314. When the first electrode 30 is bent to form the electrode assembly 22, the space occupied by the reinforcing structures 331 of the first stacked segment 313 and 332 of the second stacked segment 314 can be adjusted, making reasonable use of the space between different electrode layers. This improves the space utilization rate of the electrode assembly 22 within the battery cell 20, thereby increasing the energy density of the battery cell 20.

[0185] In some embodiments, the reinforcing structures 331 of the first laminated segment 313 and the reinforcing structures 332 of the second laminated segment 314 are arranged at equal intervals in the width direction W of the first electrode 30. Specifically, for such... Figures 6 to 9 In the corresponding configuration shown, the reinforcing structures 331 of the first laminated segment 313 and the reinforcing structures 332 of the second laminated segment 314 are arranged at equal intervals along the width direction W of the first electrode 30. This indicates that the intervals between the multiple reinforcing structures 331 of the first laminated segment 313 arranged along the width direction W of the first electrode 30 are equal, and correspondingly, the intervals between the multiple reinforcing structures 332 of the second laminated segment 314 arranged along the width direction W of the first electrode 30 are also equal. For example, Figure 11 The misalignment shown indicates that the reinforcing structures 331 of the first laminated segment 313 and 332 of the second laminated segment 314 are arranged at equal intervals along the width direction W of the first electrode 30. The distances between the first reinforcing structure 331 of the first laminated segment 313 and the two closest reinforcing structures 332 of the second laminated segment 314 are W5 and W6, respectively, where W5 equals W6. Similarly, the distances between the second reinforcing structure 332 of the second laminated segment 314 and the two closest reinforcing structures 331 of the first laminated segment 313 are W6 and W7, respectively, where W6 equals W7. And so on, the distance between any reinforcing structure 331 of the first laminated segment 313 and the closest reinforcing structure 332 of the second laminated segment 314 is W5.

[0186] By arranging the reinforcing structures 331 of the first stacked segment 313 and 332 of the second stacked segment 314 at equal intervals along the width direction W of the first electrode 30, the reinforcing structures 331 of the first stacked segment 313 and 332 of the second stacked segment 314 can be arranged uniformly, which facilitates processing and ensures that the reinforcing structures 33 are evenly distributed. This reduces the risk of misalignment in different areas of the first stacked segment 313 and the second stacked segment 314 when the first electrode 30 is bent, thereby improving the processing efficiency and the pass rate of the electrode assembly 22.

[0187] In some embodiments, the reinforcing structure 331 of the first stacked segment 313 includes a protrusion protruding from the surface of the first stacked segment 313, and the reinforcing structure 332 of the second stacked segment 314 includes a protrusion protruding from the surface of the second stacked segment 314, wherein the protrusion direction of the reinforcing structure 331 of the first stacked segment 313 is opposite to the protrusion direction of the reinforcing structure 332 of the second stacked segment 314. Thus, after the first electrode 30 is bent along the bending section 32, the first stacked section 313 and the second stacked section 314 are stacked, and the protruding direction of the reinforcing structure 331 of the first stacked section 313 is consistent with the protruding direction of the reinforcing structure 332 of the second stacked section 314. When the reinforcing structure 332 of the second stacked section 314 protrudes from one side of the second stacked section 314 and is recessed from the other side, the portion of the reinforcing structure 331 protruding from the surface of the first stacked section 313 can be accommodated in the recessed portion of the reinforcing structure 332 of the second stacked section 314, thereby reducing the gap between different electrode layers. For example, if both the first stacked section 313 and the second stacked section 314 are formed with protruding reinforcing structures 33 by means such as stamping, then one side of the reinforcing structure 33 protrudes from other areas of the stacked section 31, while the other side is recessed into other areas of the stacked section 31. If the first electrode 30 is bent along the bending section 32, and the reinforcing structure 331 of the first stacked section 313 and the reinforcing structure 332 of the second stacked section 314 have at least a partial overlap area and protrude in the same direction, then the protruding part of the reinforcing structure 331 of the first stacked section 313 can be located in the recessed part of the reinforcing structure 332 of the second stacked section 314, or the protruding part of the reinforcing structure 332 of the second stacked section 314 can be located in the recessed part of the reinforcing structure 331 of the first stacked section 313. This saves space between the two stacked sections 31, that is, reduces the distance between the two stacked sections 31, which can improve the space utilization rate of the electrode assembly 22 inside the battery cell 20, thereby improving the energy density of the battery cell 20.

[0188] Figure 12 A partial structural schematic diagram of the first electrode 30 according to another embodiment of this application is shown, and Figure 12 The diagram shows the unfolded state of the first pole piece 30, for example, the... Figure 12 This can be the state before the first electrode 30 is wound or stacked to form the electrode assembly 22. Figure 13 This is a partial enlarged view of the first electrode 30 in another embodiment of this application, for example, the... Figure 13 for Figure 12 A magnified view of region D.

[0189] like Figures 12 to 13 As shown, with Figure 6The difference is that the bending section 32 is provided with a notch 34 extending along the width direction W of the first electrode 30. On the one hand, the notch 34 can be used to position the bending section 32, reduce the offset of the first electrode 30 at the bend, and thus reduce the offset between different electrodes of the electrode assembly 22; on the other hand, the notch 34 can also reduce the difficulty of bending and reduce the resistance during bending, thereby improving the processing efficiency of the electrode assembly 22.

[0190] It should be understood that the embodiments of this application Figure 12 and Figure 6 The difference lies in notch 34. Figure 12 Other structures are suitable for Figures 6 to 9 For the sake of brevity, the relevant descriptions will not be repeated here.

[0191] In this embodiment, the structure of the notch 34 can be flexibly configured according to actual applications. For example, the notch 34 can be a through hole, which facilitates processing and greatly reduces resistance during bending, thereby improving the processing efficiency of the electrode assembly 22. Alternatively, the notch 34 can be a groove. This reduces resistance during bending and minimizes the loss of structural strength of the first electrode 30 of the electrode assembly 22.

[0192] Furthermore, if the notch 34 is a groove, it can be implemented in various ways. For example, the groove can be achieved by locally thinning the first electrode 30, so that the thickness of the bottom wall of the groove is less than the thickness of the area of ​​the first electrode 30 excluding the groove. As another example, the opening direction of the groove can be flexibly set according to the actual application. For instance, after bending the first electrode 30, the opening of the groove can face the center of the electrode assembly 22, or it can face a direction away from the center of the electrode assembly 22; the embodiments of this application are not limited to this.

[0193] In some embodiments, if the bending area 32 of this application includes a plurality of grooves 34, for example, it may include a plurality of grooves 34 arranged along the width direction W of the first electrode 30, then the structural types of the plurality of grooves 34 may be the same or different. For example, some grooves 34 may be configured as through holes, while other grooves 34 may be configured as grooves; or, all grooves 34 may be configured as through holes. This application is not limited to this.

[0194] In this embodiment, the number of notches 34 includes multiple notches, and the reinforcing structure 33 corresponds to the connection area between two adjacent notches 34 in the multiple notches 34, so that the reinforcing structure 33 and the multiple notches 34 cooperate with each other to jointly position and limit the position of the bending section 32, and improve the structural strength of the first electrode 30 in the area around the bending section 32. When the first electrode 30 is bent, misalignment or wrinkling of different areas of the first electrode 30 along the width direction W is avoided as much as possible, thereby improving the processing efficiency and yield of the electrode assembly 22.

[0195] It should be understood that the size of the notch 34 in the embodiments of this application can be set according to actual applications. Figure 14 A partial structural schematic diagram of the first electrode 30 according to another embodiment of this application is shown, and Figure 14 The diagram shows the unfolded state of the first pole piece 30, for example, the... Figure 14 This can be the state before the first electrode 30 is wound or stacked to form the electrode assembly 22. Additionally, for ease of explanation, this... Figure 14 Only the multiple grooves 34 arranged along the width direction W of the first electrode 30 are shown, and the reinforcing structure 33 is not shown. However, the first electrode 30 can also be provided with the reinforcing structure 33, which is applicable to the relevant description above. For the sake of brevity, it will not be described again here.

[0196] like Figure 14 As shown, the number of grooves 34 includes multiple grooves, including edge grooves 341 located at both ends of the first electrode 30 along the width direction W of the first electrode 30 and middle grooves 342 located in the middle region of the first electrode 30. The length W10 of the edge grooves 341 along the width direction W of the first electrode 30 is greater than the length W20 of the middle grooves 342 along the width direction W of the first electrode 30. Considering that when the bending section 32 of the first electrode 30 is bent, the resistance at both ends of the first electrode 30 along the width direction W is greater than the resistance at the middle position, and the crease fluctuation at the edge position of the first electrode 30 is greater, by setting the length W10 of the edge crease 341 along the width direction W to be greater than the length W20 of the middle crease 342 along the width direction W, the resistance at the edge position of the first electrode 30 can be reduced more significantly, the fluctuation can be reduced, and the probability of the first electrode 30 deflecting during bending can be further reduced. This can also reduce the possibility of active material precipitation or electrode assembly 22 failure, and improve the processing efficiency and pass rate of electrode assembly 22.

[0197] It should be understood that the width direction W of the first electrode 30 in this embodiment can be... Figure 14 As shown, the first electrode 30, vertically upward, includes at both ends along the width direction W. Figure 14The first electrode 30 shown has an upper edge and a lower edge. Therefore, the plurality of grooves 34 in this embodiment may include at least one edge groove 341 located near the upper edge and / or at least one edge groove 341 located near the lower edge.

[0198] Furthermore, when the plurality of notches 34 include a plurality of edge notches 341, the lengths of the plurality of edge notches 341 along the width direction W of the first electrode 30 may be equal or unequal, and the length W10 of the edge notches 341 along the width direction W of the first electrode 30 in this embodiment may refer to the average, minimum, or maximum value of the lengths of the plurality of edge notches 341 along the width direction W. For example, as Figure 14 As shown, taking the plurality of grooves 341 including two edge grooves 341 as an example, the length of the upper edge groove 341 along the width direction W is W11, and the length of the lower edge groove 341 along the width direction W is W12. Then, in this embodiment of the application, the length W10 of the edge groove 341 along the width direction W of the first electrode 30 can be the minimum value of the lengths W11 and W12, but this embodiment of the application is not limited to this.

[0199] Similar to the edge notch 341, the notch 34 in this embodiment may include at least one intermediate notch 342 located in the middle region of the first electrode 30. If the notch 34 includes multiple intermediate notches 342, the lengths of the multiple intermediate notches 342 along the width direction W of the first electrode 30 may be equal or unequal, and the length W20 of the intermediate notches 342 along the width direction W of the first electrode 30 in this embodiment may refer to the average, minimum, or maximum value of the lengths of the multiple intermediate notches 342 along the width direction W. For example, as Figure 14 As shown, taking multiple notches 342 including five intermediate notches 342 as an example, the lengths of the five intermediate notches 342 along the width direction W in a top-to-bottom order are W21, W22, W23, W24, and W25, respectively. Therefore, the lengths W21, W22, W23, W24, and W25 of these five intermediate notches 342 can be set to be equal to facilitate processing. For example, as... Figure 14 As shown, taking the five intermediate notches 342 with lengths of W21, W22, W23, W24 and W25 along the width direction as an example, the length W20 of the intermediate notches 342 along the width direction W in this embodiment can be the maximum value among the lengths W21 to W25, but this embodiment is not limited to this.

[0200] In some embodiments, when the plurality of notches 34 include a plurality of intermediate notches 342, the spacing of the plurality of intermediate notches 342 along the width direction W of the first electrode 30 may be equal or unequal. Specifically, as Figure 14As shown, taking the plurality of etched marks 34 including five intermediate etched marks 342 as an example, the lengths of the spacing between the five intermediate etched marks 342 along the width direction W in the order from top to bottom are D12, D23, D34 and D45 respectively. It can also be set that the five intermediate etched marks 342 satisfy that the spacing distances D12, D23, D34 and D45 are all equal.

[0201] In this way, by setting multiple intermediate grooves 342 with equal lengths along the width direction W, the number of times the dimensional accuracy of different intermediate grooves 342 needs to be adjusted can be reduced, thus reducing the processing difficulty. By setting multiple intermediate grooves 342 with equal intervals along the width direction W, that is, by making the intermediate grooves 342 evenly distributed along the width direction W, the force on the middle area of ​​the first electrode 30 along the width direction W can be uniform, making it easier to bend, reducing the processing difficulty of the electrode assembly 22, and thus improving the processing efficiency and pass rate of the electrode assembly 22.

[0202] In this embodiment, the size of the notch 34 can also be different. Figure 14 The arrangement of the grooves 34 is as follows. For example, there are multiple grooves 34 arranged along the width direction W of the first electrode 30, and the lengths of the multiple grooves 34 are equal. By setting the dimensions of the multiple grooves 34 arranged along the width direction W to be equal, the number of times the dimensions of the grooves 34 need to be adjusted during processing can be reduced, the processing difficulty can be reduced, and the processing efficiency can be improved.

[0203] In some embodiments, along the length L of the first electrode 30, the notch 34 is located at the middle of the bent section 32. Specifically, as shown... Figures 12 to 14 As shown, the notch 34 is located at the middle of the bending section 32 along the length L of the first electrode 30, or in other words, the notch 34 is located at the middle of the bending section 32 along the bending direction, so that when the first electrode 30 is bent along the notch 34, the positioning is more accurate, and the misalignment and offset of the first electrode 30 are minimized, thereby improving the processing efficiency and yield of the electrode assembly 22.

[0204] In this embodiment of the application, the first electrode 30 can be used to process and form the electrode assembly 22. For example, the first electrode 30 can be a positive electrode or a negative electrode.

[0205] In some embodiments, the first electrode 30 is a negative electrode without a negative electrode. Specifically, the first electrode 30 may include a negative electrode current collector, and the two opposing surfaces of the negative electrode current collector are not coated with a negative electrode active material. This results in a thinner first electrode 30, which, when assembled into an electrode assembly 22 and disposed within the battery cell 20, improves the space utilization of the electrode assembly 22, thereby increasing the energy density of the battery cell 20. Furthermore, because the first electrode 30 is thinner, it is more prone to misalignment or wrinkling when bent. The reinforcing structure 33 effectively reduces misalignment and wrinkling, improving the processing efficiency and yield of the electrode assembly 22.

[0206] In some embodiments, the thickness of the negative electrode sheet without a negative electrode is relatively thin, and its thickness can be flexibly set according to the actual application. For example, the thickness of the negative electrode sheet without a negative electrode is usually in the range of [4μm, 30μm]; for another example, the thickness of the negative electrode sheet without a negative electrode can be further set to [5μm, 17μm]; for yet another example, the thickness of the negative electrode sheet without a negative electrode can usually be specifically set to 4μm, 5μm, 6μm, 8μm, 10μm, 12μm, 15μm, 17μm, 20μm, 22μm, 25μm, 27μm or 30μm.

[0207] As an example, the negative electrode current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0208] In some implementations, the battery cell formed by the negative electrode sheet in this application embodiment can be a negative electrode-free sodium secondary battery.

[0209] A negative electrode-less sodium secondary battery refers to a battery in which a negative electrode active material layer is not actively deposited on the negative electrode side during the battery manufacturing process. For example, a sodium metal or carbonaceous active material layer is not formed at the negative electrode through coating or deposition processes. During the first charge, sodium ions gain electrons on the anode side and deposit metallic sodium on the current collector surface to form a sodium metal phase. During discharge, the metallic sodium can be converted back into sodium ions and return to the positive electrode, achieving cyclic charging and discharging. Compared to other sodium secondary batteries, a negative electrode-less sodium secondary battery can achieve a higher energy density due to the absence of a negative electrode active material layer.

[0210] In some implementations, to improve battery performance, functional coatings such as carbonaceous materials, metal oxides, and alloys can be applied to the negative electrode side of the negative electrode of the sodium-free secondary battery to improve the conductivity of the negative electrode current collector and the uniformity of the deposited sodium metal.

[0211] In some implementations, the CB value of a sodium-ion secondary battery without a negative electrode is less than or equal to 0.1.

[0212] Specifically, the CB value is the capacity per unit area of ​​the negative electrode in a secondary battery divided by the capacity per unit area of ​​the positive electrode. Since batteries without a negative electrode contain little or no functional coating, the capacity per unit area of ​​the negative electrode is relatively small, and the CB value of the secondary battery is less than or equal to 0.1.

[0213] In some embodiments, the first electrode 30 may be a negative electrode, and the negative electrode may further include a negative current collector and a negative active material disposed on at least one surface of the negative current collector.

[0214] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0215] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc.

[0216] In some embodiments, the first electrode 30 may also be a positive electrode, which may include a positive current collector and a positive active material disposed on at least one surface of the positive current collector.

[0217] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0218] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0219] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0220] In this embodiment, the electrode assembly 22 can be formed by bending the first electrode 30. Specifically, Figure 15 A schematic diagram of the structure of the electrode assembly 22 according to an embodiment of this application is shown. For example, the electrode assembly 22 shown in 15 can be as follows: Figures 4 to 5 The diagram shows a schematic of the electrode assembly 22 included in the battery cell 20. Figure 16 A side view of the electrode assembly 22 according to an embodiment of this application is shown. For example, the... Figure 16 It can be Figure 15 This is a schematic diagram of the side of the electrode assembly 22 perpendicular to the height direction Z of the battery cell 20. For ease of explanation, as shown... Figure 15 and Figure 16 The electrode assembly 22 shown does not show a separating membrane, but a separating membrane may be provided between different electrodes of the electrode assembly 22.

[0221] like Figure 15 and Figure 16 As shown, the electrode assembly 22 in this embodiment may include a first electrode 30, and the first electrode 30 may be as described above. Figures 6 to 14 The first electrode 30 shown is configured to be bent at the bending segment 32. Specifically, the first electrode 30 includes at least one bending segment 32, and the first electrode 30 can be bent at each bending segment 32. For example, the bending direction in this embodiment may include a clockwise direction R1 and / or a counterclockwise direction R2, and the first electrode 30 may include multiple bending segments 32 with the same or different bending directions. For example, for different types of electrode assemblies 22, the first electrode 30 may include bending segments 32 with the same bending direction, forming the electrode assembly 22 after being bent in the same direction; or, as... Figures 15 to 16 As shown, the first electrode 30 may also include bending segments 32 with different bending directions, thereby forming a shape as shown in the figure. Figure 15 and Figure 16 The electrode assembly 22 shown is not limited to this embodiment.

[0222] In this embodiment, the electrode assembly further includes a plurality of second electrodes 40 with polarity opposite to that of the first electrode 30, the plurality of second electrodes 40 being alternately stacked with the plurality of stacked segments 31 along the thickness direction T of the stacked segments 31. Specifically, as shown... Figure 15 and Figure 16 As shown, taking the first electrode 30 as the negative electrode as an example, when bending the first electrode 30, the multiple stacked segments 31 of the first electrode 30 are stacked together along the thickness direction T of the stacked segment 31, that is, stacked along the width direction X of the battery cell 20; correspondingly, the multiple second electrodes 40 can be stacked between the multiple stacked segments 31. In this way, during the bending of the electrode assembly 22, it is not necessary to bend the second electrodes 40, reducing the number of bending layers and reducing the bending difficulty of the electrode assembly 22.

[0223] In some embodiments, the first electrode 30 includes a plurality of bent segments 32, wherein the bending directions of two bent segments 32 at opposite ends of the same laminated segment 31 are opposite. Specifically, as Figure 15 and Figure 16 As shown, the first electrode 30 may include multiple bent segments 32. For two bent segments 32 connecting the two ends of the same stacked segment 31, the bending directions of the two bent segments 32 can be set to be different. For example, the two bent segments 32 can be bent in a clockwise direction R1 and a counterclockwise direction R2 respectively, thereby forming a Z-shaped first electrode 30. By bending in different directions, a stacked electrode assembly 22 is formed. This structure is simple and easy to implement.

[0224] In the embodiments of this application, such as Figure 15 and Figure 16 As shown, the reinforcing structure 33 can protrude from the surface of the stacked segment 31, and here we take an example where the protrusion direction of the reinforcing structure of the stacked segment 31 is consistent. However, the reinforcing structure 33 may change after subsequent processing of the electrode assembly 22 and during the use of the battery cell 20 after assembly.

[0225] For example, the reinforcing structure 33 is an indentation 330 on the surface of the laminated segment 31. Specifically, Figure 17 A schematic diagram of the structure of the electrode assembly 22 according to an embodiment of this application is shown. For example, the... Figure 17 The electrode assembly 22 shown can be as follows: Figures 4 to 5 The schematic diagram shown is of the electrode assembly 22 included in the battery cell 20, and, in comparison Figure 17 and Figure 15 ,Should Figure 17 It can be like Figure 15 The diagram shows the electrode assembly 22 after the reinforcement structure 33 of the electrode assembly 22 has been changed. Figure 18 A side view of the electrode assembly 22 according to an embodiment of this application is shown. For example, the... Figure 18 It can be Figure 17 The schematic diagram shown is of the side of the electrode assembly 22 perpendicular to the height direction Z of the battery cell 20. Correspondingly, the Figure 18 It can be like Figure 16 The diagram shows the electrode assembly 22 after the reinforcement structure 33 has been modified. For ease of explanation, [the diagram is incomplete and requires further context]. Figure 15 and Figure 16 Similarly, such as Figure 17 and Figure 18 The electrode assembly 22 shown does not show a separating membrane, but a separating membrane may be provided between different electrodes of the electrode assembly 22.

[0226] like Figure 17 and Figure 18 As shown, the reinforcing structure 33 can be an indentation 330 on the surface of the laminated section 31. That is, the reinforcing structure 33 may not protrude from the surface of other areas of the laminated section 31, but may be flush with the surface of other areas of the laminated section 31, leaving a mark on the surface of the laminated section 31. In this way, the reinforcing structure 33 can be used to limit the position of the bending section 32 during the bending of the first electrode 30. Afterwards, the reinforcing structure 33, as an indentation 330 on the surface of the laminated section 31, can also avoid occupying the gaps between different electrode layers of the electrode assembly 22, thereby improving the space utilization rate of the electrode assembly 22 inside the battery cell 20 and thus improving the energy density of the battery cell 20.

[0227] It should be understood that the reinforcing structure 33 in the embodiments of this application can be formed into an indentation 330 in various ways. The variations of the reinforcing structure 33 in the embodiments of this application will be illustrated below with reference to the accompanying drawings. Figure 19 A schematic flowchart of a method 700 for manufacturing an electrode assembly 22 according to an embodiment of this application is shown. Figure 19 As shown, the method 700 includes: S710, providing a first electrode 30, the first electrode 30 including a stacked section 31 and a bent section 32, the bent section 32 connecting the stacked section 31, and a reinforcing structure 33 being provided in the region of the stacked section 31 near the bent section 32; S720, bending the first electrode 30 in the bent section 32 to form an electrode assembly 22.

[0228] It should be understood that the first electrode 30 of method 700 can be as follows: Figures 6 to 14Any of the first electrode sheets 30 shown, for example, may be provided with a reinforcing structure 33. During the process of bending the first electrode sheet 30 to form the electrode assembly 22, the bending position of the first electrode sheet 30 can be restricted, so that the first electrode sheet 30 bends at the bending section 32, reducing the bending misalignment of the first electrode sheet 30. It can also reduce the wrinkles in the area of ​​the stacked section 31 near the bending section 32, improve the processing accuracy of the electrode assembly 22, and thus improve the processing pass rate and performance of the electrode assembly 22. For example, it can reduce the lithium plating phenomenon caused by the misalignment or wrinkles of the first electrode sheet 30, thereby improving the reliability of the electrode assembly 22.

[0229] In addition, the electrode assembly 22 can be formed by bending the bending segment 32, and different types of electrode assemblies 22 can be obtained by different bending methods. The embodiments of this application are not limited to this.

[0230] Specifically, as described above, the reinforcing structure 33 of this application embodiment can be implemented in a variety of ways. For example, the reinforcing structure 33 can be a reinforcing sheet disposed on the surface of the first electrode 30. During subsequent processing and use of the battery cell 20, the changes in the reinforcing structure 33 may be related to the material of the reinforcing sheet.

[0231] For example, the reinforcing structure 33 can also be formed by stamping or other methods. Specifically, the method 700 further includes: stamping the laminated section 31 along the thickness direction T to form a protruding structure on the surface of the laminated section 31, the reinforcing structure 33 including the protruding structure; and extruding the laminated section 31 of the electrode assembly 22. The reinforcing structure 33 formed by stamping protrudes from the surface of other areas of the laminated section 31, and the reinforcing structure 33 protrudes relative to the first surface 311 of the laminated section 31 and is recessed relative to the second surface 312 of the laminated section 31, the first surface 311 and the second surface 312 being disposed opposite to each other. When the first electrode 30 is bent, the reinforcing structure 33 formed in this way can be used to limit the bending position of the first electrode 30, so that the first electrode 30 bends at the bending section 32, reducing the bending misalignment of the first electrode 30, and also reducing wrinkles in the area of ​​the laminated section 31 near the bending section 32.

[0232] In some embodiments, employing this raised reinforcing structure 33 can correspondingly achieve the following: Figure 15 and Figure 16 The electrode assembly 22 is shown. To further reduce the interlayer gap of the electrode assembly 22, it can be extruded to obtain the desired result. Figure 17 and Figure 18The electrode assembly 22 is shown. The size of the reinforcing structure 33 protruding from other areas of the laminated section 31 after extrusion is reduced, and it can even be basically flush with other areas of the laminated section 31, reducing the distance between the first electrode 30 and the second electrode 40, thereby reducing the ion conduction path and improving the performance of the electrode assembly 22.

[0233] It should be understood that the electrode assembly 22 in this application embodiment may be squeezed during subsequent processing, or it may be squeezed during the subsequent use of the battery cell 20.

[0234] In some embodiments, extruding the laminated segment 31 of the electrode assembly 22 according to this application includes extruding the laminated segment 31 by hot pressing. For example, Figure 15 and Figure 16 The electrode assembly 22 shown can be obtained by hot-pressing the laminated segments 31 to achieve the desired result. Figure 17 and Figure 18 The electrode assembly 22 shown.

[0235] In this embodiment, due to the hot pressing process, the originally protruding reinforcing structure 33 is squeezed, thereby reducing the size of the reinforcing structure 33 protruding from other areas of the stacked segment 31, and it may even become basically flush with other areas of the stacked segment 31, thus becoming an indentation 330 on the surface of the stacked segment 31; and, through the hot pressing process, the distance between the first electrode 30 and the second electrode 40 can be further reduced, thereby reducing the ion conduction path, and the space utilization rate of the electrode assembly 22 inside the battery cell 20 can also be improved, thereby improving the energy density of the battery cell 20.

[0236] It should be understood that because the reinforcing structure 33 protrudes from the surface of the laminated section 31 before hot pressing, even if the reinforcing structure 33 becomes substantially flush with other areas after hot pressing, an indentation 330 or mark will still remain on the surface of the laminated section 31. Especially when stamping the reinforcing structure 33, if the depth of the reinforcing structure 33 increases, the indentation 330 will be more noticeable. Furthermore, during the use of the battery cell 20, the color of the indented area 330 may differ from the color of other areas; for example, the color of the indentation 330 may become darker or blacker.

[0237] In some embodiments, the electrode assembly 22 can also be compressed in other ways. For example, during the use of the battery cell 20, the electrode assembly 22 may expand. After expansion, the size of the reinforcing structure 33 protruding from other areas of the stacked segment 31 will also decrease, and it can also be compressed to be substantially flush with other areas of the stacked segment 31, thus becoming an indentation 330 on the surface of the stacked segment 31. Specifically, the electrode assembly 22 may not undergo hot pressing, or after hot pressing, the reinforcing structure 33 may still protrude from the surface of other areas of the stacked segment 31; subsequently, during the use of the battery cell 20, such as during charging and discharging, the electrode assembly 22 may expand, so that the size of the protruding reinforcing structure 33 protruding from other areas of the stacked segment 31 is further reduced, or even substantially flush with other areas of the stacked segment 31, thus becoming an indentation 330 on the surface of the stacked segment 31.

[0238] Therefore, in this embodiment, a reinforcing structure 33 is provided in the region of the stacked section 31 of the first electrode 30 near the bending section 32, which increases the structural strength of the region of the stacked section 31 near the bending section 32. Since the region of the stacked section 31 near the bending section 32 has greater strength, the reinforcing structure 33 can be used to position the bending section 32. During the bending of the first electrode 30 to form the electrode assembly 22, the bending position of the first electrode 30 can be restricted, causing the first electrode 30 to bend at the bending section 32, reducing bending misalignment of the first electrode 30, and also reducing wrinkles in the region of the stacked section 31 near the bending section 32. This improves the processing accuracy of the electrode assembly 22, thereby improving the processing pass rate and performance of the electrode assembly 22. For example, it can reduce lithium plating caused by misalignment or wrinkles of the first electrode 30, thereby improving the reliability of the electrode assembly 22.

[0239] In addition, during subsequent processing or use, the reinforcing structure 33 of the electrode assembly 22 can also be transformed into an indentation 330 on the surface of the electrode assembly 22. This can avoid occupying the gap between different electrode layers of the electrode assembly 22, reduce the distance between the first electrode 30 and the second electrode 40, thereby reducing the ion conduction path, and also improve the space utilization rate of the electrode assembly 22 inside the battery cell 20, thereby increasing the energy density of the battery cell 20.

[0240] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, the battery cell comprising an electrode assembly (22), the electrode assembly (22) comprising a first electrode (30) and a plurality of second electrodes (40), the plurality of second electrodes (40) having opposite polarities to the first electrode (30), the first electrode (30) comprising: Stacked segment (31). Multiple bending segments (32) are connected to the stacked segments (31). The bending segments (32) are used for bending. The bending directions of the two bending segments (32) at both ends of the same stacked segment (31) are opposite. In this configuration, each of the plurality of second electrode plates (40) is located between two adjacent stacked segments (31) in the plurality of stacked segments (31). The plurality of second electrode plates (40) and the plurality of stacked segments (31) are alternately stacked along the thickness direction of the stacked segments (31). A reinforcing structure (33) is provided in the region of the stacked segment (31) near the bending segment (32). The ratio of the shortest length between the end of the reinforcing structure (33) near the bending segment (32) and the centerline of the bending segment (32) to the thickness of the first electrode plate (30) is in the range of [0.016, 0.5].

2. The battery cell according to claim 1, wherein, The ratio of the shortest length between the end of the reinforcing structure (33) near the bending section (32) and the centerline of the bending section (32) to the thickness of the first electrode (30) ranges from [0.05, 0.4].

3. The battery cell according to claim 1, wherein, The reinforcing structure (33) includes a protrusion structure that protrudes from the surface of the stacked segment (31).

4. The battery cell according to claim 3, wherein, The ratio of the protrusion height of the protrusion structure relative to the thickness of the stacked segment (31) ranges from [0.3, 50].

5. The battery cell according to claim 4, wherein, The ratio of the protrusion height of the protrusion structure relative to the thickness of the stacked segment (31) is in the range of [8, 20].

6. The battery cell according to claim 3, wherein, The protruding structure protrudes relative to the first surface (311) of the stacked segment (31), and the protruding structure is recessed relative to the second surface (312) of the stacked segment (31), wherein the first surface (311) and the second surface (312) are disposed opposite to each other; and / or, The protruding structure includes a reinforcing sheet disposed on the surface of the laminated segment (31).

7. The battery cell according to any one of claims 1 to 6, wherein, The ratio of the stiffness of the reinforcing structure (33) to the stiffness of the other regions of the laminated segment (31) excluding the reinforcing structure (33) ranges from [1.5, 65].

8. The battery cell according to claim 7, wherein, The ratio of the stiffness of the reinforcing structure (33) to the stiffness of the other regions of the laminated segment (31) excluding the reinforcing structure (33) ranges from [10, 25].

9. The battery cell according to any one of claims 1 to 6, wherein, The stiffness of the reinforced structure (33) ranges from [10 N / m to 300 N / m].

10. The battery cell according to claim 9, wherein, The stiffness of the reinforced structure (33) ranges from [50 N / m to 150 N / m].

11. The battery cell according to any one of claims 1 to 6, wherein, The reinforcing structure (33) does not pass through the centerline of the laminated segment (31) in the length direction of the first electrode (30), and the ratio of the span of the reinforcing structure (33) along the length direction of the first electrode (30) to the length of the laminated segment (31) is in the range of [10%, 50%].

12. The battery cell according to any one of claims 1 to 6, wherein, The ratio of the span of the reinforcing structure (33) along the length of the first electrode (30) to the length of the laminated segment (31) ranges from [10%, 100%].

13. The battery cell according to any one of claims 1 to 6, wherein, The ratio of the sum of the widths of all the reinforcing structures (33) arranged along the width direction of the first electrode (30) to the width of the first electrode (30) ranges from [1 / 3, 0.8].

14. The battery cell according to claim 13, wherein, The ratio of the sum of the widths of all the reinforcing structures (33) arranged along the width direction of the first electrode (30) to the width of the first electrode (30) ranges from [0.4, 0.6].

15. The battery cell according to any one of claims 1 to 6, wherein, The reinforcing structure (33) is inclined relative to the width direction of the first electrode (30).

16. The battery cell according to claim 15, wherein, The angle between the reinforcing structure (33) and the first electrode (30) in the width direction ranges from [45°, 135°].

17. The battery cell according to any one of claims 1 to 6, wherein, The region of the laminated section (31) near the bent section (32) is provided with a plurality of the reinforcing structures (33) arranged along the width direction of the first electrode (30).

18. The battery cell according to claim 17, wherein, Multiple reinforcing structures (33) are arranged at equal intervals along the width direction of the first electrode (30).

19. The battery cell according to claim 18, wherein, Multiple of the reinforcing structures (33) protrude from the surface of the stacked segment (31) and protrude in the same direction.

20. The battery cell according to any one of claims 1 to 6, wherein, The first electrode (30) includes a plurality of stacked segments (31), and the bending segment (32) connects the first stacked segment (313) and the second stacked segment (314) among the plurality of stacked segments (31). The reinforcing structure (33) is provided in the region of the first stacked segment (313) near the bending segment (32) and the region of the second stacked segment (314) near the bending segment (32).

21. The battery cell according to claim 20, wherein, The reinforcing structure (331) of the first laminated segment (313) and the reinforcing structure (332) of the second laminated segment (314) are positioned correspondingly in the width direction of the first electrode (30); and / or, The reinforcing structure (331) of the first stacked segment (313) and the reinforcing structure (332) of the second stacked segment (314) are misaligned in the width direction of the first electrode (30).

22. The battery cell according to claim 21, wherein, The reinforcing structure (331) of the first stacked segment (313) and the reinforcing structure (332) of the second stacked segment (314) are arranged at equal intervals in the width direction of the first electrode (30).

23. The battery cell according to claim 21 or 22, wherein, The reinforcing structure (331) of the first laminated segment (313) includes a protrusion protruding from the surface of the first laminated segment (313), and the reinforcing structure (332) of the second laminated segment (314) includes a protrusion protruding from the surface of the second laminated segment (314). The protruding direction of the reinforcing structure (331) of the first stacked segment (313) is opposite to the protruding direction of the reinforcing structure (332) of the second stacked segment (314).

24. The battery cell according to any one of claims 1 to 6, wherein, The bent section (32) is provided with a groove (34) extending along the width direction of the first electrode (30).

25. The battery cell according to claim 24, wherein, The number of the grooves (34) includes multiple ones, and the reinforcing structure (33) corresponds to the connection area between two adjacent grooves (34) in the multiple grooves (34).

26. The battery cell according to claim 25, wherein, The number of the grooves (34) includes a plurality of grooves (34), which include edge grooves (341) located at both ends of the width direction of the first electrode (30) and a middle groove (342) located in the middle region of the first electrode (30). The length of the edge grooves (341) along the width direction of the first electrode (30) is greater than the length of the middle grooves (342) along the width direction of the first electrode (30).

27. The battery cell according to claim 25, wherein, The number of the grooves (34) includes a plurality of grooves, and the lengths of the plurality of grooves (34) are equal along the width direction of the first electrode (30).

28. The battery cell according to any one of claims 25 to 27, wherein, Along the length of the first electrode (30), the groove (34) is located in the middle of the bent section (32).

29. The battery cell according to any one of claims 1 to 6, wherein, The first electrode (30) is a negative electrode without a negative electrode.

30. The battery cell according to any one of claims 1 to 6, wherein, The reinforcing structure (33) is an indentation on the surface of the laminated segment (31).

31. A battery, comprising: Multiple battery cells, wherein the battery cells are battery cells as described in any one of claims 1 to 30.

32. An electrical appliance, comprising: The battery cell as described in any one of claims 1 to 30, or the battery as described in claim 31, wherein the battery cell or the battery is used to provide electrical energy to the electrical device.

33. A method for manufacturing an electrode assembly, comprising: A first electrode (30) and a plurality of second electrodes (40) are provided, the plurality of second electrodes (40) having opposite polarities to the first electrode (30). The first electrode (30) includes a stacked segment (31) and a plurality of bent segments (32), the bent segments (32) connecting the stacked segment (31). Each of the plurality of second electrodes (40) is located between two adjacent stacked segments (31). The second electrode (40) and a plurality of the stacked segments (31) are alternately stacked along the thickness direction of the stacked segments (31). A reinforcing structure (33) is provided in the region of the stacked segment (31) near the bending segment (32). The ratio of the shortest length between the end of the reinforcing structure (33) near the bending segment (32) and the centerline of the bending segment (32) to the thickness of the first electrode (30) is in the range of [0.016, 0.5]. The first electrode (30) is bent in the bending section (32) to form an electrode assembly, wherein the bending directions of the two bending sections (32) at both ends of the same stacked section (31) are opposite.

34. The method according to claim 33, wherein, The method further includes: The laminated section (31) is stamped along its thickness direction to form a raised structure on the surface of the laminated section (31), and the reinforcing structure (33) includes the raised structure. The stacked segment (31) of the electrode assembly is compressed.

35. The method according to claim 34, wherein, The stacked segment (31) of the extruded electrode assembly includes: The stacked segments (31) of the electrode assembly are extruded by hot pressing.

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