Negative electrode sheet, battery cell, battery and electrical device

Abstract

A negative electrode sheet, a battery cell, a battery and an electrical device. The negative electrode sheet comprises a negative electrode current collector, a first active membrane and a second active membrane, and the two active membranes are arranged on two main planes of the negative electrode current collector respectively. The first active membrane comprises at least one first active region and at least one second active region, the first active region and the second active region being spaced apart in the length direction of the negative electrode sheet, and when the negative electrode sheet is located in a battery, the first active membrane is located on the main plane of the negative electrode sheet close to the center of the battery, and the second active membrane is located on the main plane away from the center of the battery, the first active region being located in a bending region, and the second active region being located in a flat region. Each first active region comprises at least one first pore channel, and the first pore channels can be communicated with the outside of the negative electrode sheet. With respect to the negative electrode sheet, the battery cell, the battery and the electrical device provided in the embodiments, the problems of lithium plating, black spots, etc. on the inner side of the bending region of the negative electrode sheet can be ameliorated, thus prolonging the service life of the battery.

Description

Negative electrode sheets, battery cells, batteries and electrical equipment

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on July 21, 2023, with application number 202310911886.4 and application name “Negative electrode sheet, battery cell, battery and electrical equipment”, and the Chinese patent application filed with the State Intellectual Property Office of China on August 2, 2023, with application number 202310968643.4 and application name “Negative electrode sheet, battery cell, battery and electrical equipment”, all of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of new energy technology, and specifically, to a negative electrode sheet, a battery cell, a battery, and an electrical device. Background Art

[0003] In lithium-ion batteries made using the electrode winding method, the electrodes in the core will form a bending area and a flat area. Among them, the active membrane of the negative electrode sheet facing the inner side of the bending area will be bent and squeezed, resulting in an increase in the compaction density of the active membrane sheet and a decrease in the porosity, which in turn easily leads to poor lithium ion insertion / extraction reaction kinetics in the negative electrode sheet, and lithium deposition problems on the surface of the negative electrode sheet, posing a battery safety risk. In addition, the active membrane sheet on the inner side of the bending area is difficult to be infiltrated with electrolyte, and the electrolyte retention capacity is reduced. It is easy to have insufficient electrolyte during the working cycle of the battery, and black spots will appear in the later stage of the cycle, affecting the service life of the battery.

[0004] Summary of the Invention

[0005] The present application provides a negative electrode plate, a battery cell, a battery and an electrical device, which can improve the problems of lithium plating and black spots inside the bending area of ​​the negative electrode plate and extend the service life of the battery.

[0006] In a first aspect, a negative electrode sheet is provided for use in a battery, wherein the negative electrode sheet comprises a negative electrode current collector, a first active membrane sheet and a second active membrane sheet, wherein the first active membrane sheet and the second active membrane sheet are respectively arranged on two main planes of the negative electrode current collector; the first active membrane sheet comprises at least one first active area and at least one second active area, and the first active area and the second active area are spaced apart along the length direction of the negative electrode sheet; wherein, when the negative electrode sheet is located in the battery, the first active membrane sheet is located on the main plane of the negative electrode sheet close to the center of the battery, the second active membrane sheet is located on the main plane of the negative electrode sheet away from the center of the battery, and the first active area is located in the bending area of ​​the negative electrode sheet, and the second active area is located in the flat area of ​​the negative electrode sheet; the first active area comprises at least one first channel, and the first channel is connected to the outer surface of the first active membrane sheet.

[0007] In the embodiments provided in the present application, a first channel is provided on the first active area located on the inner side of the bending area of ​​the negative electrode sheet. The first channel is connected to the outside of the negative electrode sheet, which can reduce the compaction density of the first active area when it is in a wound state and increase the porosity of the first active area, so that the electrolyte can fully infiltrate the first active area, providing more channels for the deintercalation reaction of lithium ions, and avoiding the problem of lithium deposition on the surface of the negative electrode sheet; the liquid retention capacity of the first active area can be effectively improved, thereby improving the black spots and cycle capacity diving problems caused by charge and discharge cycles in the first active area.

[0008] In combination with the first aspect, in certain implementations of the first aspect, the first active diaphragm includes at least one transition zone, which extends a preset distance from the edge of the first active zone along the flat zone, and the transition zone includes at least one second channel, which is connected to the outer surface of the first active diaphragm.

[0009] In combination with the first aspect, in certain implementations of the first aspect, a size of the first channel in a first direction is less than or equal to a size of the first active area in the first direction, and the first direction is perpendicular to the main plane of the negative electrode sheet.

[0010] In the embodiment provided in the present application, the size of the first channel in the first direction is less than or equal to the size of the first active area in the first direction, which can avoid damage to the negative electrode collector when opening the first channel and affect the tensile strength of the negative electrode sheet.

[0011] In combination with the first aspect, in certain implementations of the first aspect, a ratio of a size of the first channel in the first direction to a size of the first active area in the first direction is greater than or equal to 10%.

[0012] In the embodiments provided in the present application, the ratio of the size of the first channel in the first direction to the size of the first active area in the first direction is greater than or equal to 10%, which enables the first channel to have an appropriate volume, thereby effectively absorbing the bending and extrusion of the first active area, increasing the porosity of the first active area, reducing the compaction density, and effectively improving problems such as lithium plating and black spots.

[0013] In combination with the first aspect, in certain implementations of the first aspect, at least a portion of the first channel extends along a second direction, and the second direction is any direction parallel to the main plane of the negative electrode sheet.

[0014] In the embodiment provided in the present application, the first channel extends in any direction parallel to the main plane of the negative electrode sheet, which can fully absorb the extrusion stress generated by the bending of the negative electrode sheet, reduce the compaction density of the first active area, and improve the problems of lithium plating, black spots and cycle capacity drop of the negative electrode sheet.

[0015] In combination with the first aspect, in certain implementations of the first aspect, the first active membrane includes multiple active layers, and the first channel is provided in an active layer of the multiple active layers that is away from the negative electrode current collector.

[0016] In the embodiment provided in the present application, the first active membrane includes multiple active layers, and the first channel is arranged in an active layer of the multiple active layers that is away from the negative electrode current collector. This can further avoid the negative electrode current collector being damaged when the channel is opened, affecting the tensile strength of the negative electrode sheet. The multiple active layers can also effectively improve the energy density of the negative electrode sheet.

[0017] In combination with the first aspect, in certain implementations of the first aspect, a line width of the first channel is 5 μm to 500 μm.

[0018] In the embodiment provided in the present application, the line width of the first channel is 5μm to 500μm, which can ensure that there is a suitable volume ratio between the first channel and the first active area, so that the first channel can fully absorb the extrusion stress generated by the bending of the negative electrode plate, reduce the compaction density of the first active area, and improve the problems of lithium plating, black spots and cycle capacity drop of the negative electrode plate.

[0019] In combination with the first aspect, in certain implementations of the first aspect, a distance between two adjacent first channels in the at least one first channel is 20 μm to 2000 μm.

[0020] In the embodiment provided in the present application, the spacing between two adjacent first channels is 20μm to 2000μm, which can ensure that there is a suitable volume ratio between the first channel and the first active area, so that the first channel can fully absorb the extrusion stress generated by the bending of the negative electrode sheet, reduce the compaction density of the first active area, and improve the problems of lithium plating, black spots and cycle capacity drop of the negative electrode sheet.

[0021] In combination with the first aspect, in certain implementations of the first aspect, the electrode material of the first active membrane includes graphite material and one or more of the following materials: Si particles, SiOx particles, Si / C composite particles, Sn particles, and SnOx particles.

[0022] In the embodiments provided herein, the electrode of the first active membrane includes graphite material and one or more of Si particles, SiOx particles, Si / C composite particles, Sn particles, and SnOx particles, which can improve the activity of the battery negative electrode.

[0023] In combination with the first aspect, in certain implementations of the first aspect, a size of the first active membrane in the first direction ranges from 40 μm to 1000 μm.

[0024] In combination with the first aspect, in certain implementations of the first aspect, the cross-sectional shape of the first channel along a direction parallel to the main plane of the negative electrode sheet is any one of a circle, an ellipse and a rectangle.

[0025] In a second aspect, a battery cell is provided, comprising a negative electrode sheet, a positive electrode sheet and a separator as described in the first aspect or any possible implementation of the first aspect, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet; a positive electrode tab and a negative electrode tab, wherein the positive electrode tab is connected to the positive electrode sheet and the negative electrode tab is connected to the negative electrode sheet; and an electrolyte, wherein the positive electrode sheet and the negative electrode sheet are immersed in the electrolyte.

[0026] In a third aspect, a battery is provided, comprising one or more battery cells and a protection circuit as described in the second aspect, wherein the battery cells are electrically connected to the protection circuit.

[0027] In a fourth aspect, an electrical device is provided, the electrical device comprising the battery as described in the third aspect and an electrical load, wherein the battery is used to supply power to the electrical load. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a schematic structural diagram of a winding core provided in an embodiment of the present application.

[0029] FIG2 is an enlarged view of a partial structure of a winding core provided in an embodiment of the present application.

[0030] 3A to 3C are schematic structural diagrams of a negative electrode sheet provided in an embodiment of the present application.

[0031] 4A to 4C are schematic structural diagrams of a negative electrode sheet provided in an embodiment of the present application.

[0032] 5A to 5C are schematic structural diagrams of a negative electrode plate provided in an embodiment of the present application.

[0033] 6A to 6C are schematic structural diagrams of a negative electrode plate provided in an embodiment of the present application.

[0034] 7A to 7C are schematic structural diagrams of a negative electrode plate provided in an embodiment of the present application.

[0035] 8A to 8C are schematic structural diagrams of a negative electrode sheet provided in an embodiment of the present application.

[0036] 9A to 9C are schematic structural diagrams of a negative electrode plate provided in an embodiment of the present application.

[0037] 10A to 10C are schematic structural diagrams of a negative electrode plate provided in an embodiment of the present application.

[0038] FIG11 is a schematic structural diagram of a battery cell provided in an embodiment of the present application. DETAILED DESCRIPTION

[0039] The technical solution in this application will be described below with reference to the accompanying drawings.

[0040] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0041] In various embodiments of this application, the terms "first," "second," and so on are merely used to indicate that multiple objects are distinct. For example, the first active area and the second active area are merely used to indicate different active areas. These terms should not affect the active areas themselves or their number. The terms "first," "second," and so on should not limit the embodiments of this application in any way.

[0042] The terms "include", "comprising", "having" and variations thereof mean "including but not limited to", unless specifically emphasized otherwise.

[0043] In a battery, the cell may include a roll core and a stacked core. Figures 1 and 2 are schematic diagrams of the structure of a roll core provided in an embodiment of the present application, wherein Figure 1 is a schematic diagram of the overall structure of the roll core, and Figure 2 is a partially enlarged structural diagram of the roll core (to clearly show the electrode structure, the separator is omitted in Figure 2). The roll core can be wound by a positive electrode sheet 110, a negative electrode sheet 130, and a separator 120. Similarly, the separator 120 can be arranged between the positive electrode sheet 110 and the negative electrode sheet 130, and the number of positive electrode sheets 110 can be multiple, and the number of negative electrode sheets 130 and the separator 110 can also be multiple.

[0044] The positive electrode sheet 110 can be composed of a positive electrode current collector 112 and positive electrode active membranes 111 and 113. The positive electrode active membranes 111 and 113 can be coated on the surface of the positive electrode current collector 112 and located on the two main planes of the positive electrode current collector 112, that is, the positive electrode active membrane can be coated on both surfaces parallel to the xy plane. The material of the positive electrode current collector 112 can be a metal foil, such as aluminum. The materials of the positive electrode active membranes 111 and 113 can include electrode materials, binders, and conductive agents. Among them, the electrode materials can be lithium cobalt oxide, lithium iron phosphate, layered nickel cobalt manganese oxide, etc. The conductive agent can promote the transfer rate of electrons within the electrode and has the effect of reducing electrode polarization. The binder can maintain the bonding between the active membrane component materials and between the active membrane and the current collector.

[0045] Similarly, the negative electrode sheet 130 may be composed of a negative electrode current collector 132 and negative electrode active membranes 131 and 133. The negative electrode active membranes 131 and 133 may be coated on the surface of the negative electrode current collector 132 and respectively located on two main planes of the negative electrode current collector 132. The negative electrode current collector 132 may also be made of a metal foil, such as copper. The negative electrode active membranes 131 and 133 may also include electrode materials, a binder, and a conductive agent. The electrode material of the negative electrode sheet 130 may be a graphite material.

[0046] The negative electrode active membranes located on the two main planes of the negative electrode sheet 130 can be respectively referred to as the first active membrane 133 and the second active membrane 131. The first active membrane 133 and the second active membrane 131 can have the same composition and are formed on the two main planes of the negative electrode current collector 132 through steps such as coating, drying, and rolling. When the negative electrode sheet 130 is in a wound state, the first active membrane 133 can be located on the inner side of the negative electrode sheet 130, and the second active membrane 131 can be located on the outer side of the negative electrode sheet. For example, when a roller is placed on one main plane of the negative electrode sheet and the negative electrode sheet 130 is wound around the roller, the side of the negative electrode sheet 130 close to the roller can be referred to as the inner side of the negative electrode sheet 130, and the side facing away from the roller can be referred to as the outer side of the negative electrode sheet 130. When the negative electrode sheet 130 is located in the battery, for example, when the negative electrode sheet 130 is wound together with the positive electrode sheet 110 and the separator 120 into a battery cell and packaged into a battery, the inner side of the negative electrode sheet 130, that is, the side of the negative electrode sheet 130 close to the center of the battery, the first active membrane 133 is located on the inner side of the negative electrode sheet 130, that is, the main plane of the negative electrode sheet 130 close to the center of the battery; the outer side of the negative electrode sheet 130, that is, the side of the negative electrode sheet 130 away from the center of the battery, the second active membrane 131 is located on the outer side of the negative electrode sheet 130, that is, the main plane of the negative electrode sheet 130 away from the center of the battery.

[0047] In the winding core, the positive electrode sheet 110 and the negative electrode sheet 130 are wound, so that the positive electrode sheet 110 and the negative electrode sheet 130 form a bending area 210 and a flat area 220. The portion of the electrode located inside the bending area 210 is bent and squeezed, resulting in an increase in the compaction density of the active membrane inside the bending area 210. During the charge and discharge reaction of the battery, lithium ions are released from the positive electrode of the battery and embedded in the negative electrode. If the compaction density of the side of the negative electrode sheet 130 facing the positive electrode sheet 110 is large, it is easy to cause poor kinetics of lithium ion insertion / extraction reaction, or in other words, the lithium ions released from the positive electrode sheet 110 will be difficult to be embedded in the negative electrode sheet 130 in equal amounts, and electrons will be obtained on the surface of the negative electrode sheet 130 to form lithium, that is, lithium precipitation occurs, which can easily cause consequences such as battery combustion and explosion, and create battery safety risks. Lithium ions released from the positive electrode sheet 110 may not be embedded in the negative electrode sheet or accumulated on its surface, but may instead be embedded elsewhere on the negative electrode sheet, resulting in purple spots. Furthermore, when the active membrane inside the bend region 210 of the negative electrode sheet 130 has a high compaction density and low porosity, it is difficult for the electrolyte to penetrate the active membrane, reducing the electrolyte retention capacity of the negative electrode sheet 130. This can easily lead to electrolyte insufficiency during the battery's operating cycle. In the later stages of the cycle, black spots, indicating the precipitation of graphite electrode material, can easily appear on the negative electrode sheet 130, causing a drop in cycle capacity, shortening the battery's service life.

[0048] Therefore, the embodiment of the present application provides a negative electrode sheet 130 to reduce the compaction density inside the negative electrode sheet 130 and improve the problems of lithium plating, black spots, etc. of the negative electrode sheet 130. The structure of the negative electrode sheet 130 can be referred to the structure shown in Figures 3A to 10C, wherein Figures 3A, 4A, 5A, 6A, 7A, 8A, 9A, and 10A are top views of the negative electrode sheet 130 in an unfolded state, Figures 3B, 4B, 5B, 6B, 7B, 8B, 9B, and 10B are schematic cross-sectional views of the negative electrode sheet 130 in the unfolded state along the AA direction shown in the figure, and Figures 3C, 4C, 5C, 6C, 7C, 8C, 9C, and 10C are enlarged structural views of the bending region 210 of the negative electrode sheet 130 in a wound state.

[0049] As shown in Figures 3A to 10C, the first active membrane 133 may include at least one first active area 1331 and at least one second active area 1332. The at least one first active area 1331 and the at least one second active area 1332 may be spaced apart from each other along the winding direction of the negative electrode sheet 130, and the first active area 1331 may be located in the bending area 210 of the negative electrode sheet 130 when the negative electrode sheet 130 is in the wound state, and the second active area 1332 may be located in the flat area 220 of the negative electrode sheet 130 when the negative electrode sheet 130 is in the wound state.

[0050] It should be noted that the at least one first active area 1331 and the at least one second active area 1332 are spaced apart from each other, which may mean that when the negative electrode sheet 130 is in an unfolded or flattened state, the at least one first active area 1331 and the at least one second active area 1332 are spaced apart along the winding direction of the negative electrode sheet 130. The winding direction of the negative electrode sheet 130 is the longitudinal direction of the negative electrode sheet 130, that is, the x-axis direction shown in the figure. When winding the negative electrode sheet 130, a roller can be placed on the negative electrode sheet and wound along the longitudinal direction of the negative electrode sheet, with the first active area 1331 located in the bent area 210 after winding and the second active area 1332 located in the flat area 220 after winding. The flat area 220 can be the portion of the negative electrode plate 130 where the curvature at each point is approximately zero when the negative electrode plate 130 is in the wound state, that is, the planar portion of the negative electrode plate 130. The planar portion can be parallel to the xy plane shown in the figure. In the structures shown in Figures 1 and 2, the flat area 220 is the plane corresponding to the straight portion, that is, the flat area forms a plane. The second active area 1332 is located in the flat area 220, which can refer to the entire flat area 220 as the second active area 1332. The bending area 210 of the negative electrode plate 130 can refer to the portion of the negative electrode plate 130 where the curvature is not zero when the negative electrode plate 130 is in the wound state, that is, the bending area forms a curved surface. The curvature of each point on the bending area 210 can be the same or different. The bending area 210 can be the area corresponding to the arc portion shown in Figures 1 or 2, and the portion of the negative electrode plate 130 corresponding to the bending area 210 can be rectangular when not wound. The first active area 1331 is located in the bend area 210, and the entire bend area 210 may be the first active area 1331. The first active area 1331 and the second active area 1332 are simply different regions of the first active membrane 133. The components of the first active area 1331 and the second active area 1332 can be the same, including the components and mass ratios of the active materials, conductive agents, and binders used. They can also be formed together through coating, drying, and rolling processes. When the negative electrode sheet 130 is in the unfolded state, the first active area 1331 and the second active area 1332 can have the same compaction density.

[0051] The first active area 1331 may include one or more pores 1333, which may also be referred to as first pores. When there are multiple pores 1333, the pores 1333 may be evenly distributed throughout the first active area 1331, and at least a portion of the pores 1333 may communicate with the outer surface of the first active membrane 133. The outer surface of the first active membrane 133 is the side of the first active membrane 133 that is away from the negative electrode current collector. In other words, the pores 1333 may be open, forming a concave and convex crenel structure with the portion of the first active area 1331 where the pores 1333 are not provided.

[0052] The holes 1333 can be provided starting from the junction of the first active area 1331 and the second active area 1332 and evenly distributed throughout the first active area 1331. The junction of the first active area 1331 and the second active area 1332 can refer to the edge of the first active area 1331 near the second active area 1332, and the holes 1333 can be provided at this edge. Alternatively, the first active area 1331 can be provided starting from a position a certain distance from the second active area 1332 and evenly distributed throughout the first active area 1331.

[0053] It should be noted that when an active membrane, such as the first active membrane 133, is coated on the negative electrode sheet 130, a plurality of pores may be naturally formed inside the first active membrane 133 during the drying and subsequent rolling process. The pores 1333 may refer to pores 1333 additionally formed in the first active area 1331 of the first active membrane 133 by means of pore making, etc. The pore making method may include convex rolling, acupuncture, laser engraving, chemical etching, etc., which is not limited in this application.

[0054] It should be noted that the multiple first channels in this application can also be set to be uneven. For example, the size of the first channel gradually narrows from the middle to both sides. The specific design form needs to be determined according to the actual product design requirements and is not specifically limited in this application.

[0055] In the embodiment provided herein, one or more channels 1333 are provided in the first active region 1331, and at least a portion of the channels 1333 is connected to the outer surface of the first active membrane 133. This can reduce the compaction density of the first active region 1331 in the wound state, increase the porosity of the first active region 1331, and thereby enable the electrolyte to better infiltrate the negative electrode plate 130, increase the contact area between the negative electrode plate 130 and the electrolyte, provide more channels for electrode liquid infiltration and lithium ion transmission, promote the insertion / extraction reaction of lithium ions, and slow down or eliminate the problems of lithium deposition and purple spots on the surface of the negative electrode plate 130. In addition, the increased porosity of the first active region 1331 allows the first active region 1331 to absorb more electrolyte, improve the electrolyte retention capacity of the first active membrane 133, avoid the problem of electrolyte shortage during battery cycling, thereby slowing down or eliminating the problem of black spots on the surface of the negative electrode plate 130 and the problem of cycle capacity drop, and extending the battery life.

[0056] In some embodiments, the first active diaphragm may further include a transition zone, which may extend a preset distance from the edge of the first active zone along the flat zone, and the transition zone may include at least one second channel, which may be connected to the outer surface of the first active diaphragm 133 (not shown in the figure); in other words, the transition zone may be located in the flat zone of the negative electrode plate 130, and extend a preset distance (for example: 5 mm) from the edge of the bending zone along the flat zone to form the transition zone, and a second channel may be opened in the transition zone, and the structural form of the second channel may be the same as that of the channel 1333, or may be different from the channel 1333.

[0057] In some embodiments, at least a portion of the channel 1333 may extend along a second direction, and the second direction may be any direction parallel to the main plane of the negative electrode plate 130 .

[0058] Referring to the negative electrode plate 130 structure shown in Figures 3A to 3C , the channel 1333 can extend along the width of the negative electrode plate 130 and can penetrate the first active area 1331 along the width of the negative electrode plate 130. In this example, the width of the negative electrode plate 130 is the y-axis direction shown in the figure. This width direction is parallel to the main plane of the negative electrode plate 130 and can also be referred to as the second direction. There can be multiple channels 1333, or in other words, each first active area 1331 can include multiple channels 1333. The multiple channels 1333 can be arranged parallel to each other and can be evenly distributed in the first active area 1331.

[0059] It should be noted that in the embodiments of the present application, the parallelism between the structural members may be approximately parallel, rather than absolutely parallel, and a certain angular error is allowed. Similarly, in the following description, the perpendicularity between the structural members may be approximately perpendicular, and the equal size may be approximately equal size.

[0060] In some embodiments, the size of the channel 1333 in the first direction can be equal to the size of the first active area 1331 in the first direction. The first direction is the thickness direction of the negative electrode plate 130, that is, the z-axis direction shown in the figure, as shown in FIG3B . In other words, the channel 1333 can pass through the first active area 1331 along the first direction, forming an opening perpendicular to the negative electrode current collector.

[0061] The size of the pore 1333 in the first direction is equal to the size of the first active area 1331 in the first direction, which can prevent the pore 1333 from extending onto the negative electrode collector in the first direction and affecting the tensile strength of the negative electrode sheet 130 .

[0062] The line width of the channel 1333 can be 5 μm to 500 μm. The line width of the channel 1333 can be the diameter of the largest circle that can fit within the planar projection area of ​​the negative electrode plate 130 along the first direction. The cross-section of the channel 1333 along the xy plane shown in FIG3A is rectangular. The line width of the channel 1333 can be the dimension of the channel 1333 in the x-axis direction.

[0063] Exemplarily, the line width of the channel 1333 can be 20 μm to 50 μm, for example, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, etc.

[0064] The line width of the channel 1333 is 5μm to 500μm, which enables the channel 1333 to better absorb the bending stress of the first active area 1331 in the bent state, reduce the compaction density of the first active area 1331, and thus avoid problems such as lithium deposition and black spots on the surface of the first negative electrode plate 130.

[0065] When there are multiple channels 1333, the spacing between two adjacent channels 1333 can be 20 μm to 2000 μm. The spacing between two adjacent channels 1333 can be the spacing between two adjacent sides of the two adjacent channels 1333. The spacing between the channels 1333 shown in FIG3 can be the distance between two adjacent sides of the two adjacent channels 1333 in the x-axis direction.

[0066] For example, the distance between two adjacent channels 1333 may be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, etc.

[0067] It should be noted that the dimensions, such as the line width and spacing, of the pores 1333 referred to in the embodiments of the present application may refer to the corresponding dimensions of the pores 1333 when the negative electrode sheet 130 is in the unfolded state. When the negative electrode sheet 130 is in the wound state, the first active area 1331 is subjected to compressive stress and will deform, and the dimensions, such as the line width and spacing, may vary to a certain extent. Similarly, the dimensions, such as the thickness of the first active area 1331 or the first active membrane 133, may also refer to the corresponding dimensions when the negative electrode sheet 130 is in the unfolded state.

[0068] When the negative electrode plate 130 includes multiple first active areas 1331 , the structures and sizes of the channels 1333 included in the multiple first active areas 1331 , as well as the distribution positions of the channels 1333 in the first active areas 1331 , can be the same, so as to improve the production efficiency of the negative electrode plate 130 .

[0069] Figure 3C shows the structure of the negative electrode sheet 130 near the bend region 210 when in a wound state. A roller can be placed above the negative electrode sheet 130 shown in Figure 3B , that is, above it in the z-axis direction, and the negative electrode sheet 130 can be wound around the roller in the positive x-axis direction to achieve the state shown in Figure 3C . When the negative electrode sheet 130 is in the wound state, the pores 1333 can absorb the compressive stress on the first active area 1331, reducing the compaction density of the first active area 1331. The electrolyte can fully fill the pores 1333, providing more channels for lithium ion insertion and extraction reactions, avoiding lithium plating problems, and improving the negative electrode sheet 130's liquid retention capacity, avoiding the problems of black spots and cycle capacity drops.

[0070] Figures 4A to 4C illustrate another embodiment of the present invention, showing another embodiment of a channel 1333. The cross-sectional structure of the channel 1333 along the xy plane can be similar to that shown in Figure 3A and will not be further described here. The dimension of the channel 1333 in the first direction can also be smaller than the dimension of the first active area 1331 in the first direction, as shown in Figure 4B.

[0071] For example, the ratio of the size of the pore 1333 in the first direction to the size of the first active area 1331 in the first direction can be greater than or equal to 10%, that is, can be 10% to 100%. For example, the size of the first active area 1331 in the first direction can be 40 μm to 1000 μm. When the size of the first active area 1331 in the first direction is 150 μm, the size of the pore 1333 in the first direction can be 75 μm. Alternatively, the size of the pore in the first direction can be 15 μm, 30 μm, 45 μm, 60 μm, 90 μm, etc.

[0072] The dimension of the pores 1333 in the first direction is smaller than the dimension of the first active area 1331 in the first direction. When forming the pores 1333, a larger machining margin can be left on the first active membrane 133, thereby better preventing damage to the negative current collector and thus affecting the tensile strength of the negative electrode sheet 130. The pores 1333 shown in Figures 5A to 5C can extend along the winding direction of the negative electrode sheet 130, or in other words, along the length of the negative electrode sheet 130, and can penetrate the first active area 1331 along the length of the negative electrode sheet 130. In this example, the length direction of the negative electrode sheet 130 is the x-axis direction shown in the figure. This length direction is parallel to the main plane of the negative electrode sheet 130 and can also be referred to as the second direction.

[0073] The channels 1333 extend along the winding direction of the negative electrode sheet 130. The channels 1333 in multiple first active areas 1331 can be processed sequentially along the x-axis direction using the same processing parameters, which can improve the production efficiency of the negative electrode sheet 130 and facilitate mass production.

[0074] Similarly, the size of the pore 1333 of the negative electrode plate 130 in the first direction can be smaller than the size of the first active area 1331 in the first direction, as shown in Figure 5B, or it can be equal to the size of the first active area 1331 in the first direction (not shown in Figure 5B) to avoid the pore 1333 extending onto the negative electrode current collector.

[0075] The line width of the channels 1333 of the negative electrode sheet 130 shown in Figures 5A to 5C may also be 5μm to 500μm, and the spacing between two adjacent channels 1333 in the plurality of channels 1333 may also be 20μm to 2000μm. The channels 1333 shown in Figures 5A to 5C extend along the x-axis and have a rectangular cross-sectional shape in the xy plane. The line width of the channels 1333 may be the dimension of the channels 1333 in the y-axis direction shown in the figure, and the spacing between adjacent channels 1333 may be the dimension of the two adjacent sides of the two adjacent channels 1333 in the y-axis direction shown in the figure.

[0076] Figure 5C shows the structure of the negative electrode sheet 130 in a wound state. Since the channel 1333 extends along the x-axis when the negative electrode sheet 130 is in the unwound state and penetrates the first active area 1331 along the x-axis, the cross-sectional shape of the channel 1333 on the xz plane can be arc-shaped when the negative electrode sheet 130 is in the wound state. The bending and extrusion of the first active area 1331 can cause the channel 1333 to deform in a direction perpendicular to the paper, that is, the y-axis direction, to balance the compressive stress on the first active area 1331, reduce the compaction density of the first active area 1331, and avoid problems such as lithium deposition and black spots.

[0077] Figures 6A to 6C illustrate another structure of a negative electrode sheet 130 provided in an embodiment of the present application. The extension direction of the channel 1333 may also form a certain angle with the width or length direction of the negative electrode sheet 130, and may extend through the first active area 1331 along this extension direction. In other words, the cross-sectional shape of the channel 1333 parallel to the main plane of the negative electrode sheet 130 may approximate a parallelogram.

[0078] Similar to the channels 1333 described in Figures 3A to 5C above, the line width of each channel 1333 can be 5 μm to 500 μm, and the line width of each channel 1333 can be the distance between the two hypotenuses of a parallelogram, that is, the distance between the two sides of the parallelogram that form a certain angle with the x-axis. The spacing between two adjacent channels 1333 in the plurality of channels 1333 can be 20 μm to 2000 μm, and the spacing can be the distance between the two adjacent hypotenuses of the two adjacent channels 1333.

[0079] The size of the channel 1333 in the first direction may be smaller than the size of the first active area 1331 in the first direction, as shown in FIG6B , or may be equal to the size of the first active area 1331 in the first direction (not shown).

[0080] Figure 6C shows the structure of the negative electrode sheet 130 in a wound state. Since the channel 1333 extends at a certain angle to the x-axis when the negative electrode sheet 130 is in the unwound state and can penetrate the first active area 1331, the cross-section of the channel 1333 along the xz plane has a larger dimension in the x-direction. When the negative electrode sheet 130 is in the wound state, the first active area 1331 is subjected to bending and compression, which can cause the channel 1333 to deform inwardly. This balances the compressive stress on the first active area 1331, reduces the compaction density of the first active area 1331, and avoids problems such as lithium deposition and black spots.

[0081] The channel 1333 shown in Figures 3A to 6C above can pass through the first active area 1331 in any direction on the main plane parallel to the negative electrode plate 130. The channel 1333 provided in the embodiment of the present application can be arranged in the first active area 1331 without passing through the first active area 1331, see the examples shown in Figures 7A to 8C.

[0082] In the negative electrode sheet shown in Figures 7A to 7C , the cross-section of the channel 1333 along a plane parallel to the main plane of the negative electrode sheet 130 can be rectangular, and the rectangular cross-section can be provided within the first active area 1331, rather than passing through the first active area 1331, as shown in Figure 7A . There can be multiple channels 1333, and multiple rectangular channels 1333 can be included in the first active area 1331 along the x-axis, and multiple rectangular channels 1333 can also be included in the first active area 1331 along the y-axis. The multiple rectangular channels 1333 can be arranged in an array within the first active area 1331.

[0083] The flattened shape of the rectangular channel 1333 on the AA section can be similar to the shape of the channel 1333 on the AA section shown in FIG3B or FIG4B , as shown in FIG7B . The structural shape of the AA section after winding can also be similar to that shown in FIG3C or FIG4C , as shown in FIG7C , and will not be repeated here.

[0084] In the negative electrode sheet shown in Figures 8A to 8C , the cross-sectional shape of the channel 1333 along the principal plane parallel to the negative electrode sheet 130 can be elliptical, and the elliptical shape can be provided within the first active area 1331, rather than passing through the first active area 1331, as shown in Figure 8A . Similarly, the first active area 1331 can include multiple elliptical channels 1333 along the x-axis, and the first active area 1331 can also include multiple elliptical channels 1333 along the y-axis. The multiple elliptical channels 1333 can be arranged in an array within the first active area 1331.

[0085] The flattened and wound shapes of the elliptical channel 1333 on the AA section can also be similar to the flattened and wound shapes of the channel 1333 on the AA section shown in Figures 3B, 3C, 4B and 4C, respectively, and will not be repeated here.

[0086] The cross-sectional shape of the channel 1333 along the main plane parallel to the negative electrode plate 130 can also be a well shape, an S shape, a wave shape, a ring shape, a circle, or an irregular shape, etc. This application does not limit the shape of the channel 1333.

[0087] The negative electrode plate 130 shown in Figures 3A to 8C above is provided with a channel 1333 in the first active area 1331 to reduce the compaction density of the first active area 1331. The second active area 1332 of the negative electrode plate 130 provided in the embodiment of the present application can also be provided with a channel 1334, see the structure shown in Figures 9A to 9C.

[0088] The volume ratio of the pores 1333 to the first active area 1331 can be greater than the volume ratio of the pores 1334 to the second active area 1332. That is, the volume ratio of the pores 1333 per unit volume of the first active area 1331 is greater than the volume ratio of the pores 1334 per unit volume of the second active area 1332. The pore volume ratio of the first active area 1331 is greater than the pore volume ratio of the second active area 1332. The pore volume ratio of each first active area 1331 can be greater than the pore volume ratio of each second active area 1332. For example, the spacing between the pores 1333 in the first active area 131 can be smaller than the spacing between the pores 1334 in the second active area 132.

[0089] Similarly, the size of the pore 1334 in the first direction may also be smaller than or equal to the size of the second active area 1332 in the first direction to prevent the pore 1334 from extending to the negative electrode current collector and affecting the tensile strength of the negative electrode sheet 130 .

[0090] The arrangement of the channel 1334 on the second active area 1332 may also be similar to the arrangement of the channel 1333 on the first active area 1331. For example, the channel 1334 may also extend in the second direction and may pass through the second active area 1332, or may not pass through the second active area 1332.

[0091] The cross-sectional shape of the channel 1334 parallel to the main plane of the negative electrode plate 130 can also be rectangular, well-shaped, S-shaped, wavy, annular, circular, or irregular. The channels 1333 in the embodiments of the present application are merely schematic illustrations of the shape, distribution, and structure of the channels 1333, and the shape and number of the channels 1333 should not be limited. Providing channels 1334 on the second active area can mean providing channels 1334 throughout the second active area 1332.

[0092] As described above, there may be multiple second active areas 1332 , and each of the multiple second active areas 1332 may be provided with one or more channels 1334 .

[0093] In some embodiments, the first active membrane 133 may include multiple active layers, and the pores 1333 of the first active region 1331 may be disposed in a layer of the multiple active layers that is away from the negative electrode current collector 132. For example, in the negative electrode sheet 130 shown in Figures 10A to 10C, the first active membrane 133 of the negative electrode sheet 130 may include two active layers 1335 and 1336, with the active layer 1335 being close to the negative electrode current collector 132 and the active layer 1336 being away from the negative electrode current collector 132. The pores 1333 may be disposed in the active layer 1336 to further prevent the pores from extending into the negative electrode current collector in the thickness direction when the pores are disposed, thereby damaging the negative electrode current collector and affecting the tensile strength of the negative electrode sheet. Furthermore, the provision of multiple active layers can improve the energy density of the negative electrode sheet.

[0094] The size of the pore 1333 in the first direction can be smaller than or equal to the size of the active layer 1336. The active layer 1335 and the active layer 1336 can have the same or different components.

[0095] The pores described in Figures 3A to 10C extend along the z-axis from the outer surface of the first active membrane 133 toward the negative electrode current collector. In other words, the cross-sectional shape of the pores along the xz plane can be a regular linear pore. For example, such a linear pore can be formed by laser engraving, needle punching, or punch rolling. The cross-sectional shape of the pores along the xz plane can also be a curved irregular shape (not shown in the figures). For example, if the pores are formed by chemical etching, such irregular shapes can be formed. This application does not limit the shape of the pores.

[0096] In the embodiment provided in the present application, the electrode material of the negative electrode plate 130 may include, in addition to graphite material, one or more of Si particles, SiOx particles, Si / C composite particles, Sn particles, SnOx particles, etc. The electrode material of the negative electrode plate 130 includes one or more of Si particles, SiOx particles, Si / C composite particles, Sn particles, SnOx particles, etc., which can improve the activity of the negative electrode plate.

[0097] The first active membrane 133 of the negative electrode plate 130 in the embodiment of the present application can have a size in the first direction of 40 μm to 1000 μm, for example, 40 μm, 50 μm, 60 μm, 80 μm, 100 μm, etc. The negative electrode plate provided in the embodiment of the present application can have a relatively large thickness. When the negative electrode plate is thicker, the degree of bending and compression on the inner side of the bending area is greater, which makes it more likely to cause problems such as lithium deposition and black spots. The provision of the pores 1333 can effectively improve the lithium deposition and black spot problems of the negative electrode plate.

[0098] The charge and discharge potential of the negative electrode plate 130 in the embodiment of the present application is lower than that of the positive electrode plate 110. For example, the charge and discharge potential of the negative electrode plate 130 may be 0 to 1.2V, and the charge and discharge potential of the positive electrode plate 110 may be greater than 2V, for example, 3 to 5V.

[0099] The structure of the first active membrane 133 located within the bend region 210 of the negative electrode sheet 130 provided in the embodiment of the present application has been described in detail above in conjunction with Figures 3A to 10C . In the embodiment provided in the present application, the second active membrane 131 can be located outside the bend region 210. The second active membrane 131 can be a single integral structure, distributed both in the bend region 210 and in the flat region 220. The components of the second active membrane 131 can be the same as those of the first active membrane 133. The portion of the second active membrane 131 located in the flat region can also be provided with one or more pores (not shown in the figures), while the portion located in the bend region can be provided with no pores. The structural morphology of the pores in the second active membrane 131 can be similar to that of the pores 1333. Similar to the pores 1334 of the first active membrane 131, the volume ratio of the pores to the flat area on the second active membrane 131 can be smaller than the volume ratio of the pores 1333 to the first active area. For example, the spacing between the pores on the second active membrane 131 can be larger than the spacing between the pores 1333. The second active membrane 131 can have a single-layer structure or a multi-layer structure. When the second active membrane 131 has a multi-layer structure, the pores on the second active membrane can be arranged in the active layer away from the negative electrode current collector.

[0100] An embodiment of the present application also provides a battery cell, which may include any one of the negative electrode sheets described in Figures 3A to 10C above, as well as a positive electrode sheet and a separator. The negative electrode sheet, the positive electrode sheet and the separator are wound to form a core and encapsulated in the battery cell shell 160. The battery cell may also include a positive electrode tab 140 and a negative electrode tab 150. The positive electrode tab 140 is connected to the positive electrode sheet, and the negative electrode tab 150 is connected to the negative electrode sheet. The battery cell shell 160 may include a through hole so that at least part of the negative electrode tab 150 and the positive electrode tab 140 can extend out of the shell 160 from the through hole to facilitate connection with an external electrical load and supply power to the electrical load.

[0101] The battery cell may further include an electrolyte (not shown in the figure), which may be encapsulated in the shell 160 , and the positive electrode sheet 110 , the negative electrode sheet 130 and the separator 120 may be immersed in the electrolyte.

[0102] The present application also provides a battery, which may include a cell as described in FIG11 , which may be further encapsulated in a battery housing. The battery may also include a protection circuit, which may be electrically connected to the cell.

[0103] The battery can be a lithium-ion battery, a sodium-ion secondary battery, a potassium-ion secondary battery, a magnesium-ion secondary battery, a zinc-ion secondary battery, an aluminum-ion secondary battery, etc. The above embodiment takes a lithium-ion battery as an example, and provides a channel 1333 inside the bending region of the negative electrode plate to improve problems such as lithium deposition and black spots. Similar to lithium-ion batteries, for the above sodium-ion and potassium-ion batteries, etc., the inside of the bending region of the negative electrode plate may also exhibit problems such as deposition of sodium, potassium, magnesium, zinc, aluminum, etc. dendrites, as well as black spots. The use of the above negative electrode plate can also improve similar problems of sodium-ion secondary batteries, potassium-ion secondary batteries, magnesium-ion secondary batteries, zinc-ion secondary batteries, and aluminum-ion secondary batteries.

[0104] An embodiment of the present application also provides an electrical device, which can use a battery made of the negative electrode sheet provided in the embodiment of the present application. The electrical device can also include an electrical load, and the battery can be used to power the electrical load.

[0105] For example, the power-consuming device may be an electronic device including the battery and electronic components described above, wherein the battery may be used to power the electronic components. The electronic device may be a mobile phone, a tablet computer, a laptop computer, a smartwatch, or a power bank, and the present application does not limit this.

[0106] The power-consuming device may also be an electric vehicle, comprising the battery described above and an onboard load, wherein the battery can be used to power the onboard load. The electric vehicle may be a pure electric vehicle, a hybrid electric vehicle, or an extended-range electric vehicle, and the onboard load may include in-vehicle air conditioning, lights, speakers, and other equipment, which are not limited in this application.

[0107] It should be noted that the electronic devices and electric vehicles described above are only examples of application scenarios of the negative electrode plates, battery cells and batteries described in this application. The negative electrode plates, battery cells and batteries provided in this application can also be used in other electrical equipment, such as ship equipment, aerospace equipment, etc.

[0108] The present application also provides an energy storage system, which may include multiple batteries as described above, and a power converter, wherein the power converter is used to convert the voltage output by the battery into power and output it to the power grid or external load, and / or the power converter is used to convert the voltage output by the external power supply into power and output it to the battery. The energy storage system can be a charging pile, a site backup power supply, a mobile base station power supply, etc., and can also be an energy storage system for scenarios such as home energy storage, outdoor energy storage, power station energy storage, industrial and commercial energy storage, and distributed energy storage, which is not limited by this application.

[0109] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A negative electrode plate, characterized in that: Applied to a battery, the negative electrode sheet comprises a negative electrode current collector, a first active membrane sheet and a second active membrane sheet, wherein the first active membrane sheet and the second active membrane sheet are respectively arranged on two main planes of the negative electrode current collector; The first active membrane comprises at least one first active area and at least one second active area, and the first active area and the second active area are arranged at intervals along the length direction of the negative electrode sheet; Wherein, when the negative electrode sheet is located in the battery, the first active membrane sheet is located on the main plane of the negative electrode sheet close to the center of the battery, the second active membrane sheet is located on the main plane of the negative electrode sheet away from the center of the battery, and the first active area is located in the bending area of ​​the negative electrode sheet, and the second active area is located in the flat area of ​​the negative electrode sheet; The first active area includes at least one first channel, and the first channel is connected to the outer surface of the first active membrane.

2. The negative electrode sheet according to claim 1, characterized in that: The first active membrane includes a transition zone extending from an edge of the first active zone along the flat zone for a preset distance, and the transition zone includes at least one second channel communicating with an outer surface of the first active membrane.

3. The negative electrode sheet according to claim 1 or 2, characterized in that: The size of the first channel in a first direction is smaller than or equal to the size of the first active area in the first direction, and the first direction is perpendicular to the main plane of the negative electrode sheet.

4. The negative electrode sheet according to claim 3, characterized in that: A ratio of a size of the first channel in the first direction to a size of the first active area in the first direction is greater than or equal to 10%.

5. The negative electrode sheet according to any one of claims 1 to 4, characterized in that: The first channel extends along a second direction, and the second direction is any direction parallel to the main plane of the negative electrode plate.

6. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The first active membrane comprises a plurality of active layers, and the first pore is arranged in an active layer of the plurality of active layers which is far away from the negative electrode current collector.

7. The negative electrode sheet according to any one of claims 1 to 6, characterized in that: The line width of the first channel is 5 μm to 500 μm.

8. The negative electrode sheet according to any one of claims 1 to 7, characterized in that: The distance between two adjacent first channels in the at least one first channel is 20 μm to 2000 μm.

9. The negative electrode sheet according to any one of claims 1 to 8, characterized in that: The electrode material of the first active membrane includes a graphite material and one or more of the following materials: Si particles, SiOx particles, Si / C composite particles, Sn particles and SnOx particles.

10. The negative electrode sheet according to any one of claims 1 to 9, characterized in that: The size of the first active membrane in the first direction ranges from 40 μm to 1000 μm.

11. The negative electrode sheet according to any one of claims 1 to 10, characterized in that: The cross-sectional shape of the first channel along the direction parallel to the main plane of the negative electrode plate is any one of a circle, an ellipse, a parallelogram and a rectangle.

12. A battery cell, characterized in that: include: The negative electrode sheet, the positive electrode sheet and the separator according to any one of claims 1 to 11, wherein the separator is arranged between the positive electrode sheet and the negative electrode sheet; A positive electrode tab and a negative electrode tab, wherein the positive electrode tab is connected to the positive electrode sheet, and the negative electrode tab is connected to the negative electrode sheet; An electrolyte, wherein the positive electrode sheet and the negative electrode sheet are immersed in the electrolyte.

13. A battery, characterized in that: The method comprises one or more battery cells and a protection circuit as claimed in claim 12, wherein the battery cells are electrically connected to the protection circuit.

14. An electrical device, characterized in that: It comprises the battery as claimed in claim 13 and an electrical load, wherein the battery is used to supply power to the electrical load.

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