Negative pole piece, battery cell, battery and electric equipment

Abstract

The invention provides a negative pole piece, a battery cell, a battery and electric equipment, the negative pole piece comprises a negative current collector, a first active membrane and a second active membrane, and the two active membranes are respectively arranged on two main planes of the negative current collector; 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 are arranged at intervals along the length direction of the negative pole piece, and when the negative pole piece is positioned in the battery, the first active membrane is positioned on a main plane, close to the center of the battery, of the negative pole piece; the second active diaphragm is positioned on a main plane far away from the center of the battery, the first active region is positioned in the bending region, and the second active region is positioned in the flat region; each first active region comprises at least one first pore channel, and the first pore channel can be communicated with the outside of the negative pole piece. According to the negative pole piece, the battery cell, the battery and the electric equipment provided by the embodiment of the invention, the problems of lithium precipitation, black spots and the like on the inner side of the bending area of the negative pole piece can be improved, and the service life of the battery is prolonged.

Description

[0001] This application claims the priority of 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”, all contents of which are incorporated by reference in 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 winding 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 and a decrease in the porosity, which in turn easily leads to poor insertion / extraction reaction kinetics of lithium ions in the negative electrode sheet, and lithium precipitation problems on the surface of the negative electrode sheet, creating battery safety risks. In addition, the electrolyte infiltration of the active membrane on the inner side of the bending area is difficult, and the electrolyte retention capacity is reduced. The problem of insufficient electrolyte is prone to occur during the working cycle of the battery, and black spots appear in the later stage of the cycle, affecting the service life of the battery. Summary of the invention

[0004] The present application provides a negative electrode plate, a battery cell, a battery and an electrical device, which can improve the lithium plating and black spot problems inside the bending area of ​​the negative electrode plate and extend the service life of the battery.

[0005] 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 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 comprises at least one first channel, and the first channel is connected to the outer surface of the first active membrane sheet.

[0006] 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, and 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 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 precipitation 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 the charge and discharge cycles in the first active area.

[0007] 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.

[0008] 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 a main plane of the negative electrode sheet.

[0009] 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.

[0010] 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%.

[0011] 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 can enable the first channel to have a suitable 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 deposition and black spots.

[0012] In combination with the first aspect, in some 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 plate.

[0013] 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 diving of the negative electrode sheet.

[0014] In combination with the first aspect, in some implementations of the first aspect, the first active membrane includes a plurality of active layers, and the first channel is disposed in an active layer of the plurality of active layers that is away from the negative electrode current collector.

[0015] In the embodiment provided in the present application, the first active membrane includes a plurality of active layers, and the first channel is arranged in an active layer of the plurality of active layers that is away from the negative electrode current collector. This can further avoid damage to the negative electrode current collector when the channel is opened, thereby affecting the tensile strength of the negative electrode plate. The multi-layer active layer can also effectively improve the energy density of the negative electrode plate.

[0016] In combination with the first aspect, in some implementations of the first aspect, a line width of the first channel is 5 μm to 500 μm.

[0017] In the embodiments provided in the present application, the line width of the first channel is 5 μm to 500 μm, 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 diving of the negative electrode plate.

[0018] 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.

[0019] In the embodiments provided in the present application, the spacing between two adjacent first channels is 20 μm to 2000 μm, which enables the first channel to have a suitable volume ratio with 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 diving of the negative electrode sheet.

[0020] In combination with the first aspect, in certain implementations of the first aspect, 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.

[0021] In the embodiments provided in the present application, the electrode of the first active membrane includes a 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 negative electrode of the battery.

[0022] 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.

[0023] In combination with the first aspect, in certain implementations of the first aspect, a cross-sectional shape of the first channel along a direction parallel to a main plane of the negative electrode plate is any one of a circle, an ellipse and a rectangle.

[0024] 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.

[0025] In a third aspect, a battery is provided, the battery comprising one or more battery cells and a protection circuit as described in the second aspect, the battery cells being electrically connected to the protection circuit.

[0026] In a fourth aspect, an electrical device is provided, the electrical device comprising the battery and an electrical load as described in the third aspect, the battery being used to supply power to the electrical load. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of a winding core provided in an embodiment of the present application.

[0028] Figure 2 It is an enlarged view of the local structure of a winding core provided in an embodiment of the present application.

[0029] FIG. 3A to FIG. 3C It is a schematic diagram of the structure of a negative electrode plate provided in an embodiment of the present application.

[0030] FIG. 4A to FIG. 4C It is a schematic diagram of the structure of a negative electrode plate provided in an embodiment of the present application.

[0031] FIG. 5A to FIG. 5C It is a schematic diagram of the structure of a negative electrode plate provided in an embodiment of the present application.

[0032] FIG. 6A to FIG. 6C It is a schematic diagram of the structure of a negative electrode plate provided in an embodiment of the present application.

[0033] 7A to 7C It is a schematic diagram of the structure of a negative electrode plate provided in an embodiment of the present application.

[0034] FIG. 8A to FIG. 8C It is a schematic diagram of the structure of a negative electrode plate provided in an embodiment of the present application.

[0035] 9A to 9C It is a schematic diagram of the structure of a negative electrode plate provided in an embodiment of the present application.

[0036] FIG. 10A to FIG. 10C It is a schematic diagram of the structure of a negative electrode plate provided in an embodiment of the present application.

[0037] Fig.11 It is a schematic diagram of the structure of a battery cell provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0039] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. appearing in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways.

[0040] In various embodiments of the present application, the first, second, etc. are only used to indicate that multiple objects are different. For example, the first active area and the second active area are only used to indicate different active areas. They should not have any impact on the active areas themselves and the number of active areas. The first, second, etc. mentioned above should not impose any limitations on the embodiments of the present application.

[0041] The terms "include", "comprising", "having" and variations thereof all mean "including but not limited to", unless specifically emphasized otherwise.

[0042] In batteries, cells can include rolled cores and stacked cores. Figure 1 and Figure 2 A schematic diagram of the structure of a winding core provided in an embodiment of the present application, wherein: Figure 1 The overall structure diagram of the winding core is shown in FIG. Figure 2 This is a partial enlarged structural diagram of the winding core (to clearly show the pole piece structure, Figure 2 The winding core may be formed by winding the positive electrode sheet 110, the negative electrode sheet 130 and the separator 120. Similarly, the separator 120 may be disposed between the positive electrode sheet 110 and the negative electrode sheet 130. The number of the positive electrode sheet 110 may be multiple, and the number of the negative electrode sheet 130 and the separator 110 may also be multiple.

[0043] The positive electrode sheet 110 may be composed of a positive current collector 112 and positive active membranes 111 and 113. The positive active membranes 111 and 113 may be coated on the surface of the positive current collector 112 and are respectively located on the two main planes of the positive current collector 112, that is, the positive active membranes may be coated on both surfaces parallel to the xy plane. The material of the positive current collector 112 may be a metal foil, such as aluminum. The materials of the positive active membranes 111 and 113 may include electrode materials, binders, and conductive agents, among which the electrode materials may be lithium cobalt oxide, lithium iron phosphate, layered nickel cobalt manganese oxide, and other materials. The conductive agent may promote the transfer rate of electrons inside the electrode and has the effect of reducing electrode polarization, and the binder may maintain the bonding between the active membrane component materials and between the active membrane and the current collector.

[0044] Similarly, the negative electrode sheet 130 may be composed of a negative electrode current collector 132 and negative electrode active films 131 and 133. The negative electrode active films 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 material of the negative electrode current collector 132 may also be a metal foil, such as copper, and the materials of the negative electrode active films 131 and 133 may also include materials such as electrode materials, binders and conductive agents. The electrode material of the negative electrode sheet 130 may be a graphite material.

[0045] The negative electrode active films located on the two main planes of the negative electrode sheet 130 can be respectively referred to as the first active film 133 and the second active film 131. The components of the first active film 133 and the second active film 131 can be the same, and they are formed on the two main planes of the negative electrode collector 132 by coating, drying and rolling. When the negative electrode sheet 130 is in a wound state, the first active film 133 can be located on the inner side of the negative electrode sheet 130, and the second active film 131 can be located on the outer side of the negative electrode sheet. Exemplarily, when a roller is set on a 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 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 isolation film 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 sheet 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 sheet 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.

[0046] 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 sheet 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. In 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 insertion / extraction reaction kinetics of lithium ions, 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 are obtained on the surface of the negative electrode sheet 130 to form lithium single substance, that is, lithium precipitation occurs, which is easy to cause consequences such as battery combustion and explosion, and create battery safety risks. The lithium ions released from the positive electrode sheet 110 may not be embedded in the negative electrode sheet, nor accumulated on the surface of the negative electrode sheet, but embedded in other positions of the negative electrode sheet, forming a purple spot phenomenon. In addition, when the compaction density of the active membrane inside the bending area 210 of the negative electrode sheet 130 is relatively large and the porosity is relatively low, it is difficult for the electrolyte to infiltrate the active membrane, and the liquid retention capacity of the negative electrode sheet 130 is reduced. In the working cycle of the battery, the problem of insufficient electrolyte is likely to occur. In the late cycle, the negative electrode sheet 130 is prone to black spots, that is, the precipitation of graphite electrode materials, and the phenomenon of cycle capacity diving occurs, which affects the service life of the battery.

[0047] Therefore, the embodiment of the present application provides a negative electrode plate 130 to reduce the compaction density inside the negative electrode plate 130 and improve the problems of lithium deposition and black spots on the negative electrode plate 130. The structure of the negative electrode plate 130 can be seen in FIG. 3A to FIG. 10C The structure shown, in which Figure 3A , Figure 4A , Figure 5A , Fig. 6A , Fig. 7A , Fig. 8A , Fig.9A as well as Fig. 10A is a top view of the negative electrode sheet 130 in an unfolded state, Figure 3B , Figure 4B , Figure 5B , Figure 6B , Figure 7B , Figure 8B , Fig. 9B as well as Fig. 10B is a schematic diagram of the cross-sectional structure of the negative electrode sheet 130 in the unfolded state along the AA direction shown in the figure, Figure 3C , Figure 4C , Figure 5C , Figure 6C , Figure 7C , Figure 8C , Fig. 9C as well as Fig. 10CIt is an enlarged structural diagram of the bending area 210 when the negative electrode sheet 130 is in a wound state.

[0048] like FIG. 3A to FIG. 10C As shown, the first active membrane 133 may include at least one first active area 1331 and at least one second active area 1332, and the at least one first active area 1331 and the at least one second active area 1332 may be arranged at intervals 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 winding 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 winding state.

[0049] 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 state or a flattened state, the at least one first active area 1331 and the at least one second active area 1332 are spaced apart from each other along the winding direction of the negative electrode sheet 130, and the winding direction of the negative electrode sheet 130 is also the length direction of the negative electrode sheet 130, that is, the x-axis direction shown in the figure. When the negative electrode sheet 130 is wound, a roller may be placed on the negative electrode sheet and wound along the length direction of the negative electrode sheet, so that the first active area 1331 is located in the bending area 210 after winding, and the second active area 1332 is located in the flat area 220 after winding. The flat area 220 may be a portion of the negative electrode sheet 130 where the curvature of each point is approximately 0 when the negative electrode sheet 130 is in a wound state, that is, a planar portion of the negative electrode sheet 130, and the planar portion may be parallel to the xy plane shown in the figure, such as Figure 1 and Figure 2 In the structure shown, the flat area 220 is the plane corresponding to the straight part, that is, the flat area forms a plane. The second active area 1332 is located in the flat area 220, which may refer to the entire flat area 220 as the second active area 1332. The bending area 210 of the negative electrode plate 130 may refer to the part of the negative electrode plate 130 whose curvature is not zero when the negative electrode plate 130 is in a wound state, that is, the bending area forms a curved surface. The curvatures of each point on the bending area 210 may be the same or different. The bending area 210 may be Figure 1 or Figure 2The area corresponding to the arc portion shown, and the portion of the negative electrode sheet 130 corresponding to the bending area 210 can be rectangular when not wound. The first active area 1331 is located in the bending area 210, which can refer to the entire bending area 210 as the first active area 1331. The first active area 1331 and the second active area 1332 are just different areas of the first active membrane 133. The components of the two can be the same, including the components and mass ratios of the active materials, conductive agents and binders used, and can be formed together through coating, drying and rolling processes. When the negative electrode sheet 130 is in an unfolded state, the compaction density of the first active area 1331 and the second active area 1332 can be the same.

[0050] 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 multiple pores 1333 may be evenly distributed in the first active area 1331, and at least part of the pores 1333 may be connected to 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 away from the negative electrode current collector, that is, the pores 1333 may be an open structure, and form a concave and convex crenel form with the part of the first active area 1331 where the pores 1333 are not provided.

[0051] The pores 1333 may be set starting from the position where the first active area 1331 and the second active area 1332 meet, and may be evenly distributed in the first active area 1331. The position where the first active area 1331 and the second active area 1332 meet may refer to the edge position of the first active area 1331 close to the second active area 1332, and the pores 1333 may be opened at the edge position. Alternatively, the first active area 1331 may also be set starting from the position where the first active area 1331 and the second active area 1332 are spaced a certain distance apart, and may be evenly distributed in the first active area 1331.

[0052] It should be noted that when an active membrane such as the first active membrane 133 is coated on the negative electrode plate 130, a plurality of pores may be naturally formed inside the first active membrane 133 itself during the drying and subsequent rolling process. The pore 1333 may refer to a pore 1333 additionally formed in the first active region 1331 of the first active membrane 133 by means of pore making or the like. The pore making method may include convex rolling, acupuncture, laser engraving, chemical etching, and the like, which is not limited in the present application.

[0053] It should be noted that the multiple first channels in the present application may also be arranged 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 the present application does not make specific restrictions.

[0054] In the embodiment provided by the present application, one or more channels 1333 are provided in the first active area 1331, and at least part of the channels 1333 is connected to the outer surface of the first active membrane 133, which can reduce the compaction density of the first active area 1331 in the winding state, increase the porosity of the first active area 1331, and thus 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 lithium precipitation and purple spots on the surface of the negative electrode plate 130. In addition, the increase in the porosity of the first active area 1331 enables the first active area 1331 to absorb more electrolyte, improve the electrolyte retention capacity of the first active membrane 133, avoid the problem of insufficient electrolyte in the cycle of the battery, thereby slowing down or eliminating the surface black spots and cycle capacity diving problems of the negative electrode plate 130, and extending the service life of the battery.

[0055] In some embodiments, the first active membrane may further include a transition zone, which may extend from the edge of the first active zone along the flat zone by a preset distance, and the transition zone may include at least one second channel, which may be connected to the outer surface of the first active membrane 133 (not shown in the figure); in other words, the transition zone may be located in the flat area of ​​the negative electrode plate 130, and extend from the edge of the bending zone along the flat area by a preset distance (for example: 5 mm) 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.

[0056] 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 .

[0057] See also FIG. 3A to FIG. 3C In the structure of the negative electrode sheet 130 shown, the channel 1333 can extend along the width direction of the negative electrode sheet 130, and can penetrate the first active area 1331 along the width direction of the negative electrode sheet 130. In this example, the width direction of the negative electrode sheet 130 is the y-axis direction shown in the figure, and the width direction is parallel to the main plane of the negative electrode sheet 130, which can also be called the second direction. The number of the channels 1333 can be multiple, or in other words, each first active area 1331 can include multiple channels 1333, and the multiple channels 1333 can be arranged in parallel with each other and can be evenly distributed in the first active area 1331.

[0058] It should be noted that in the embodiment of the present application, the structural members being parallel to each other may be approximately parallel, rather than absolutely parallel, and a certain angle error is allowed. Similarly, in the following, the structural members being perpendicular to each other may be approximately perpendicular, and being equal in size may mean being approximately equal in size.

[0059] In some embodiments, the size of the pore 1333 in the first direction may be equal to the size of the first active area 1331 in the first direction, and the first direction is the thickness direction of the negative electrode plate 130, that is, the z-axis direction shown in the figure. Figure 3B That is, the pore 1333 can penetrate the first active area 1331 along the first direction to form an opening perpendicular to the negative electrode current collector.

[0060] 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 plate 130 .

[0061] The line width of the hole 1333 may be 5 μm to 500 μm. The line width of the hole 1333 may be the diameter of a circle with the largest diameter that can fit into the plane projection area of ​​the negative electrode plate 130 along the first direction of the hole 1333 . Figure 3A The cross-sectional shape of the hole 1333 shown along the xy plane is a rectangle, and the line width of the hole 1333 may be the dimension of the hole 1333 in the x-axis direction.

[0062] Exemplarily, the line width of the channel 1333 may 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.

[0063] The line width of the channel 1333 is 5 μm to 500 μm, so that the channel 1333 can better absorb the bending stress of the first active area 1331 in a bent state, reduce the compaction density of the first active area 1331, and thus avoid lithium deposition and black spots on the surface of the first negative electrode plate 130.

[0064] When there are multiple channels 1333, the spacing between two adjacent channels 1333 of the multiple channels 1333 may be 20 μm to 2000 μm. The spacing between two adjacent channels 1333 may be the spacing between two adjacent sides of the two adjacent channels 1333. The spacing between the channels 1333 shown in FIG. 3 may be the distance between two adjacent sides of the two adjacent channels 1333 in the x-axis direction.

[0065] By way of example, the interval between two adjacent channels 1333 may be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, etc.

[0066] It should be noted that the line width and spacing of the pores 1333 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 the extrusion stress and will be deformed, and the line width and spacing may change to a certain extent. Similarly, 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.

[0067] 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 .

[0068] Figure 3C The structure diagram of the negative electrode sheet 130 near the bending area 210 when the negative electrode sheet 130 is in a wound state, and the roller can be placed Figure 3B The negative electrode sheet 130 is wound around the roller in the positive direction of the x-axis to obtain Figure 3C When the negative electrode sheet 130 is in a wound state, the pores 1333 can absorb the extrusion stress of the first active area 1331, reduce the compaction density of the first active area 1331, and the electrolyte can be fully filled into the pores 1333, providing more channels for the insertion and extraction reaction of lithium ions, avoiding the problem of lithium precipitation, and improving the liquid retention capacity of the negative electrode sheet 130, avoiding the problem of black spots and cycle capacity diving.

[0069] FIG. 4A to FIG. 4C Another structure of the duct 1333 provided in the embodiment of the present application, the cross-sectional structure of the duct 1333 along the xy plane can be Figure 3A The size of the pore 1333 in the first direction may also be smaller than the size of the first active area 1331 in the first direction, such as Figure 4B shown.

[0070] Exemplarily, 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 may be greater than or equal to 10%, that is, may be 10% to 100%. For example, the size of the first active area 1331 in the first direction may be 40 μm to 1000 μm, and 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 may be 75 μm, or the size of the pore in the first direction may also be 15 μm, 30 μm, 45 μm, 60 μm, 90 μm, etc.

[0071] The size of the pore 1333 in the first direction is smaller than that of the first active area 1331 in the first direction. When the pore 1333 is opened, a larger processing margin can be left on the first active membrane 133 to better avoid damage to the negative electrode collector and affect the tensile strength of the negative electrode plate 130. FIG. 5A to FIG. 5C The hole 1333 shown may extend along the winding direction of the negative electrode sheet 130, or in other words, extend along the length direction of the negative electrode sheet 130, and may penetrate the first active area 1331 along the length direction 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, which is parallel to the main plane of the negative electrode sheet 130 and may also be referred to as the second direction.

[0072] The pores 1333 extend along the winding direction of the negative electrode sheet 130 . The pores 1333 in the plurality of first active regions 1331 can be processed sequentially along the x-axis direction using the same processing parameters, thereby improving the production efficiency of the negative electrode sheet 130 and facilitating mass production.

[0073] Similarly, the size of the hole 1333 of the negative electrode plate 130 in the first direction may be smaller than the size of the first active area 1331 in the first direction. Figure 5B As shown, or it may be equal to the size of the first active area 1331 in the first direction ( Figure 5B (not shown) to prevent the pores 1333 from extending onto the negative electrode current collector.

[0074] FIG. 5A to FIG. 5C The line width of the hole 1333 of the negative electrode plate 130 shown may also be 5 μm to 500 μm, and the spacing between two adjacent holes 1333 in the plurality of holes 1333 may also be 20 μm to 2000 μm. FIG. 5A to FIG. 5C The channel 1333 shown extends along the x-axis direction and has a rectangular cross-sectional shape in the xy plane. The line width of the channel 1333 can be the size of the channel 1333 in the y-axis direction shown in the figure, and the spacing between adjacent channels 1333 can be the size of the two adjacent sides of two adjacent channels 1333 in the y-axis direction shown in the figure.

[0075] Figure 5C The structure of the negative electrode sheet 130 when it is in a wound state, because the channel 1333 extends along the x-axis direction when the negative electrode sheet 130 is in an unfolded state, and passes through the first active area 1331 along the x-axis direction, when the negative electrode sheet 130 is in a wound state, the cross-sectional shape of the channel 1333 on the xz plane can be arc-shaped. The first active area 1331 is subjected to bending and extrusion, which can cause the channel 1333 to deform in the direction perpendicular to the paper surface, that is, the y-axis direction, so as to balance the extrusion stress of the first active area 1331, reduce the compaction density of the first active area 1331, and avoid the problems of lithium precipitation and black spots.

[0076] FIG. 6A to FIG. 6C In another structure of the negative electrode sheet 130 provided in the embodiment of the present application, the extension direction of the channel 1333 may also form a certain angle with the width direction or the length direction of the negative electrode sheet 130, and may penetrate the first active area 1331 along the 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 be approximately a parallelogram.

[0077] With the above FIG. 3A to FIG. 5C Similar to the described channel 1333, the line width of the channel 1333 can be 5 μm to 500 μm, and the line width of the channel 1333 can be the distance between the two hypotenuses of the parallelogram, that is, the distance between the two sides of the parallelogram that form a certain angle with the x-axis direction. 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.

[0078] The size of the pore 1333 in the first direction may be smaller than the size of the first active area 1331 in the first direction. Figure 6B As shown, it may also be equal to the size of the first active area 1331 in the first direction (not shown in the figure).

[0079] Figure 6C The structure of the negative electrode sheet 130 when it is in a wound state, because the channel 1333 extends in a direction at a certain angle to the x-axis when the negative electrode sheet 130 is in an unfolded state, and can penetrate the first active area 1331, the cross section of the channel 1333 along the xz plane has a larger size in the x direction. When the negative electrode sheet 130 is in a wound state, the first active area 1331 is bent and squeezed, so that the channel 1333 is deformed toward the inside of the channel 1333, so as to balance the squeezing stress on the first active area 1331, reduce the compaction density of the first active area 1331, and avoid the problems of lithium deposition and black spots.

[0080] Above FIG. 3A to FIG. 6C The pores 1333 shown in the figure can penetrate the first active area 1331 in any direction on the main plane parallel to the negative electrode plate 130. The pores 1333 provided in the embodiment of the present application can be arranged in the first active area 1331 without penetrating the first active area 1331. 7A to 8C Example shown.

[0081] 7A to 7C In the negative electrode sheet shown in FIG. 1 , the cross-sectional shape of the channel 1333 along the main plane parallel to the negative electrode sheet 130 may be a rectangle, and the rectangular cross-sectional shape may be arranged in the first active area 1331 without penetrating the first active area 1331, as shown in FIG. Fig. 7A The number of the channels 1333 can be multiple, and the first active area 1331 along the x-axis direction can include multiple rectangular channels 1333, and the first active area 1331 along the y-axis direction can also include multiple rectangular channels 1333, and the multiple rectangular channels 1333 can be arranged in an array in the first active area 1331.

[0082] The flattened shape of the rectangular channel 1333 on the AA section can be Figure 3B or Figure 4B The shape of the channel 1333 shown in the AA section is similar, as shown in FIG. Figure 7B As shown. And the structural shape of the AA section after winding can also be Figure 3C or Figure 4C Similar to that shown, Figure 7C As shown, no further description is given here.

[0083] FIG. 8A to FIG. 8C In the negative electrode sheet shown in FIG. 1 , the cross-sectional shape of the channel 1333 along the main plane parallel to the negative electrode sheet 130 may be an ellipse, and the ellipse may be arranged in the first active area 1331 without passing through the first active area 1331, as shown in FIG. Fig. 8A Similarly, the first active area 1331 may include a plurality of elliptical channels 1333 at a position along the x-axis direction, and the first active area 1331 may also include a plurality of elliptical channels 1333 at a position along the y-axis direction. The plurality of elliptical channels 1333 may be arranged in an array in the first active area 1331 .

[0084] The flattened and wound shapes of the elliptical channel 1333 on the AA section can also be respectively Figure 3B , Figure 3C , Figure 4B as well as Figure 4C The shapes of the channel 1333 shown in the flattened state and the wound state on the AA section are similar and will not be described again here.

[0085] 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.

[0086] Above FIG. 3A to FIG. 8C The negative electrode sheet 130 shown in the figure is provided with a hole 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 sheet 130 provided in the embodiment of the present application may also be provided with a hole 1334, see 9A to 9C The structure shown.

[0087] The volume ratio of the pores 1333 to the first active area 1331 may 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, and the pore volume ratio of each first active area 1331 may be greater than the pore volume ratio of each second active area 1332. Exemplarily, the spacing between the pores 1333 on the first active area 131 may be less than the spacing between the pores 1334 on the second active area 132.

[0088] 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 collector and affecting the tensile strength of the negative electrode sheet 130 .

[0089] 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 .

[0090] The cross-sectional shape of the pore 1334 on the main plane parallel to the negative electrode plate 130 may also be rectangular, well-shaped, S-shaped, wavy, annular, circular, or irregular. The pore 1333 in the embodiment of the present application only schematically illustrates the shape, distribution and structure of the pore 1333, and the shape and number of the pore 1333 should not be limited. The pore 1334 is provided on the second active area, which may refer to the pore 1334 being provided on the entire second active area 1332.

[0091] 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 .

[0092] 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. FIG. 10A to FIG. 10C The negative electrode sheet 130 shown in the figure, the first active membrane sheet 133 of the negative electrode sheet 130 may include two active layers 1335 and 1336, the active layer 1335 is close to the negative electrode collector 132, the active layer 1336 is far away from the negative electrode collector 132, the channel 1333 can be opened in the active layer 1336 to further avoid the channel extending to the negative electrode collector in the thickness direction when opening the channel, causing damage to the negative electrode collector, affecting the tensile strength of the negative electrode sheet, etc., and the provision of multiple active layers can improve the energy density of the negative electrode sheet.

[0093] The size of the pore 1333 in the first direction may be smaller than or equal to the size of the active layer, that is, the active layer 1336. The components of the active layer 1335 and the active layer 1336 may be the same or different.

[0094] Above FIG. 3A to FIG. 10C The described pores extend from the outer surface of the first active membrane 133 in the direction close to the negative electrode current collector along the z-axis direction, that is, the cross-sectional shape of the pores along the xz plane can be a regular straight-line pore, for example, the straight-line pores can be formed by laser engraving, needle punching, punch rolling, etc. The cross-sectional shape of the pores along the xz plane can also be a curved irregular shape (not shown in the figure), for example, when the pores are formed by chemical etching, etc., they can be irregular-shaped pores, and the present application does not limit the shape of the pores.

[0095] In the embodiments 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.

[0096] The size of the first active membrane 133 of the negative electrode plate 130 in the embodiment of the present application in the first direction may be 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 may have a relatively large thickness. When the negative electrode plate is thicker, the greater the degree of bending and squeezing on the inner side of the bending area, the more likely it is to cause problems such as lithium deposition and black spots. The opening of the channel 1333 can effectively improve the lithium deposition and black spot problems of the negative electrode plate.

[0097] The charge and discharge potential of the negative electrode plate 130 in the embodiment of the present application is less 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.

[0098] Combined with the above FIG. 3A to FIG. 10C The structure of the first active membrane 133 located inside the bending area 210 of the negative electrode plate 130 provided in the embodiment of the present application is described in detail. In the embodiment provided in the present application, the second active membrane 131 can be arranged outside the bending area 210. The second active membrane 131 can be an integral structure, which can be distributed in the bending area 210 and the flat area 220, and 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 area can also be provided with one or more channels (not shown in the figure), while the portion located in the bending area can be provided with no channels, and the structural form of the channels on the second active membrane 131 can be similar to the structural form of the channels 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 may 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 may be larger than the spacing between the pores 1333. The second active membrane 131 may be a single-layer structure or a multi-layer structure. When the second active membrane 131 is a multi-layer structure, the pores on the second active membrane may be arranged in the active layer away from the negative electrode current collector.

[0099] The present application also provides a battery cell, which may include the above-mentioned FIG. 3A to FIG. 10C Any of the negative electrode sheets described, as well as the positive electrode sheets and the isolation film, the negative electrode sheets, the positive electrode sheets and the isolation film are wound into a core and encapsulated in the shell 160 of the battery cell, 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 shell 160 of the battery cell 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, so as to facilitate connection with an external electrical load and supply power to the electrical load.

[0100] 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 isolation film 120 may be immersed in the electrolyte.

[0101] The present application also provides a battery, which may include: Fig.11 The battery cell described above can be further encapsulated in a battery housing. The battery can also include a protection circuit, which can be electrically connected to the battery cell.

[0102] 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. In the above embodiment, a lithium ion battery is used as an example, and a hole 1333 is provided inside the bending area of ​​the negative electrode plate to improve the problems of lithium precipitation and black spots. Similar to lithium ion batteries, for the above sodium ion and potassium ion batteries, etc., the inside of the bending area of ​​the negative electrode plate will also have the problems of precipitation of sodium, potassium, magnesium, zinc, aluminum, etc. dendrites, and the appearance of 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.

[0103] The 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.

[0104] Exemplarily, the power-consuming device may be an electronic device, which includes the battery and electronic components described above, and 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 smart watch, or a power bank, etc., which is not limited in this application.

[0105] The power-consuming device may also be an electric vehicle, which includes the battery described above and a load on the vehicle, and the battery may be used to power the load on the vehicle. The electric vehicle may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, and the load on the vehicle may include in-vehicle air conditioning equipment, lights, speakers, and other equipment, which are not limited in this application.

[0106] 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 applied to other electrical equipment, such as ship equipment, aerospace equipment, etc.

[0107] The embodiment of the present application also provides an energy storage system, which may include multiple batteries as described above, and a power converter, which is used to convert the voltage output by the battery 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 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., or it can 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 the present application.

[0108] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope 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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