CN221125988U - Negative plate, electrode assembly and battery - Google Patents

Abstract

The utility model provides a negative electrode sheet, an electrode assembly and a battery. The negative plate comprises a negative current collector, wherein the negative current collector is provided with a first functional surface and a second functional surface which are oppositely arranged; the first functional surface is provided with a lug area and an active layer area which are connected with each other, the lug area is provided with a lug, the active layer area is provided with a first negative electrode active layer, and the surface of the first negative electrode active layer, which is far away from the negative electrode current collector, is provided with an exposed area and a dark area; the surface of the second functional surface is provided with a second negative electrode active layer, the surface of the second negative electrode active layer, which is far away from the negative electrode current collector, comprises a first area and a second area which are mutually connected, the first area is provided with an bright area and a dark area, and the second area is a dark area; the first orthographic projection of the second area on the first functional surface is at least partially overlapped with the tab area. The negative plate is not easy to separate out lithium in the charge and discharge process of the battery, and is beneficial to improving the cycle performance of the battery.

Description

Negative plate, electrode assembly and battery

Technical Field

The utility model relates to the technical field of new energy, in particular to a negative plate, an electrode assembly and a battery.

Background

The theoretical specific capacity of the silicon-based negative electrode material is ten times or more than that of the graphite-based negative electrode material, so that the silicon-based negative electrode material is widely applied to preparation of the lithium ion battery negative electrode plate. However, the first effect of the silicon-based negative electrode material is low, and the lithium supplementing layer is usually arranged on the surface of the negative electrode plate containing the silicon-based negative electrode material in the prior art so as to improve the first effect of the negative electrode plate containing the silicon-based negative electrode material. However, the negative electrode sheet provided with the lithium supplementing layer is liable to cause lithium precipitation, and thus the cycle performance of the battery is affected.

Disclosure of Invention

The utility model provides a negative plate which is not easy to separate out lithium in the charge and discharge process of a battery and is beneficial to improving the cycle performance of the battery.

The present utility model provides an electrode assembly including the above-described negative electrode sheet, thereby contributing to improved cycle performance of a battery.

The present utility model provides a battery including the above-described electrode assembly, and thus has excellent cycle performance.

The utility model provides a negative plate, which comprises a negative current collector, wherein the negative current collector is provided with a first functional surface and a second functional surface which are oppositely arranged;

The first functional surface is provided with a lug area and an active layer area which are connected with each other, the lug area is provided with a lug, the active layer area is provided with a first negative electrode active layer, and the surface of the first negative electrode active layer, which is far away from the negative electrode current collector, is provided with an exposed area and a dark area;

The surface of the second functional surface is provided with a second negative electrode active layer, the surface of the second negative electrode active layer, which is far away from the negative electrode current collector, comprises a first area and a second area which are mutually connected, the first area is provided with an bright area and a dark area, and the second area is a dark area;

The first orthographic projection of the second area on the first functional surface is at least partially overlapped with the tab area.

The negative electrode sheet as described above, wherein the length L2 of the second region and the length L1 of the tab satisfy: l2= (1.1 to 4.0) L1.

The negative electrode sheet as described above, wherein the width W2 of the second region and the width W0 of the negative electrode current collector satisfy: w2= (0.05 to 0.7) w0.

The negative electrode sheet as described above, wherein the first orthographic projection has a first center line extending in the first direction, and the tab region has a second center line extending in the first direction;

The minimum distance between the first central line and the second central line is less than or equal to 0.5mm along the second direction, and the first direction and the second direction are mutually perpendicular; and/or the number of the groups of groups,

The first orthographic projection has a third centerline extending in a second direction, and the tab region has a fourth centerline extending in the second direction;

And along the first length direction, the minimum distance between the third central line and the fourth central line is less than or equal to 0.5mm, and the first direction and the second direction are mutually perpendicular.

The negative electrode sheet as described above, wherein the thickness H2 of the negative electrode sheet in the second region, the thickness H1 of the negative electrode sheet in the first region, and the thickness H0 of the negative electrode current collector satisfy:

(H2-H0)＝(0.55～1.0)*(H1-H0)。

The utility model provides an electrode assembly, which comprises the negative electrode plate.

The electrode assembly comprises a cathode plate, a cathode plate and a protective layer, wherein the cathode plate is arranged opposite to the cathode plate and comprises a cathode body and an insulating layer arranged on at least one functional surface of the cathode body;

A second orthographic projection of the insulating layer on the second functional surface is at least partially coincident with the second region.

An electrode assembly as described above, wherein the edge of the second region is located within the edge of the second orthographic projection or the edge of the second region at least partially coincides with the edge of the second orthographic projection.

The electrode assembly as described above, wherein the tab region is formed by recessing the first anode active layer in the direction of the anode current collector, and the tab is disposed in the recess.

The present utility model provides a battery including the electrode assembly as described above.

The negative plate provided by the utility model is provided with the second area opposite to the lug area, and the second area can reduce the lithium precipitation risk of the lug area of the negative plate in the battery charging and discharging process, so that the cycle performance of the battery is improved.

The electrode assembly provided by the utility model comprises the negative electrode plate, so that lithium is not easy to separate out from the tab area of the negative electrode plate in the charge and discharge process of the battery, and the cycle performance of the battery is improved.

The battery provided by the utility model comprises the electrode assembly, so that lithium is not easy to separate out in the tab area of the negative plate in the charge and discharge process, and the battery has excellent cycle performance.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the related art, the drawings that are required to be used in the description of the embodiments of the present utility model or the related technologies are briefly described below. It is evident that the drawings in the following description are only some embodiments of the present utility model and that other drawings may be obtained from these drawings without inventive effort for a person of ordinary skill in the art.

FIG. 1 is a side view of a negative electrode sheet in some embodiments of the utility model;

FIG. 2 is a top view of a negative electrode sheet in some embodiments of the utility model;

fig. 3 is a side view of an electrode assembly in some embodiments of the utility model.

Reference numerals illustrate:

1: a negative electrode sheet;

2: a positive plate;

11: a negative electrode current collector;

12: a first anode active layer;

13: a second anode active layer;

14: a tab;

15: a lithium supplementing layer;

21: an insulating layer;

111: a tab region;

131: a second region.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

In the present utility model, all the definitions of "length" and "width" refer to the "length L direction" and "width W direction" of the negative electrode current collector. Taking a functional surface of the negative current collector (the functional surface refers to two surfaces with the largest area and opposite arrangement in the negative current collector) as an example, the length L direction of the negative current collector refers to the direction in which the largest side length of the functional surface of the negative current collector is located, and is denoted as the x direction; the width W direction of the negative current collector refers to the direction in which the minimum side length of the functional surface of the negative current collector is located, and is marked as the y direction; the thickness direction of the negative electrode current collector is denoted as the z direction. For example, the present utility model defines the length of the second region as L2, which means that the dimension of the second region in the length direction of the negative electrode current collector is L2.

FIG. 1 is a side view of a negative electrode sheet in some embodiments of the utility model; fig. 2 is a top view of a negative electrode sheet in some embodiments of the utility model. As shown in fig. 1 and 2, a first aspect of the present utility model provides a negative electrode sheet, including a negative electrode current collector 11, the negative electrode current collector 11 having a first functional surface and a second functional surface disposed opposite to each other;

the first functional surface is provided with a lug area 111 and an active layer area which are connected with each other, the lug area 111 is provided with a lug 14, the active layer area is provided with a first negative electrode active layer 12, and the surface of the first negative electrode active layer 12 far away from the negative electrode current collector 11 is provided with a bright area and a dark area;

The second functional surface is provided with a second negative electrode active layer 13, and the surface of the second negative electrode active layer 13 far away from the negative electrode current collector 11 comprises a first area and a second area 131 which are connected with each other, wherein the first area is provided with a bright area and a dark area, and the second area is a dark area;

the first orthographic projection of the second region 131 on the first functional surface at least partially coincides with the tab region 111.

In the present utility model, the two surfaces of the negative electrode current collector 11 having the largest area and being disposed opposite to each other are the first functional surface and the second functional surface of the negative electrode current collector 11, respectively.

The first functional surface of the present utility model includes a tab area 111 and an active layer area that are connected to each other, wherein the tab area 11 is provided with a tab 14, the present utility model is not limited to the manner of arranging the tab 14, and in the present utility model, die cutting processing may be performed on the tab area 11 to obtain the tab 14; tab 14 may be welded to tab region 11, and first negative electrode active layer 12 may be provided in the active layer region.

The second functional surface of the present utility model is provided with a second anode active layer 13. The first negative electrode active layer 12 and the second negative electrode active layer 13 are not particularly limited, and may be any common negative electrode active layer in the art, and the first negative electrode active layer 12 and the second negative electrode active layer 13 may be the same or different.

In the utility model, the bright area is an area with high brightness and length of more than 4mm in the obtained picture when the magnification is 4-25 times by adopting a laser scanning confocal microscope test; the dark area is the area with low brightness in the obtained picture when the magnification is 4 times to 25 times by using a laser scanning confocal microscope for testing. Specifically, a laser scanning confocal microscope (Olympus, lexthols 3100) may be used to obtain a surface topography image of the negative electrode sheet, and the bright area and the dark area may be distinguished from the image.

In some embodiments, the lithium supplementing layer 15 is disposed on the surface of the first anode active layer, which is far away from the anode current collector, after electrochemical reaction, the anode active material in the first anode active layer is intercalated with lithium to generate volume expansion, the area is raised in the first anode active layer to form a lithium supplementing area, which is shown as a higher brightness area, namely a bright area, in a laser scanning confocal microscope, and the first anode active material layer, which is not covered with the lithium supplementing layer, is a non-lithium supplementing area, which is shown as a lower brightness area, namely a dark area, in the laser scanning confocal microscope. The lithium metal foil in the lithium supplementing layer is in a stripe shape and is distributed on the surface of the first negative electrode active layer in parallel according to a certain gap width, so that the bright area and the dark area on the surface of the first negative electrode active layer are alternately distributed on the surface of the first negative electrode active layer by adopting a laser scanning confocal microscope test.

As shown in fig. 2, the surface of the second anode active layer 13 remote from the anode current collector 11 includes a first region and a second region 131 connected to each other. Wherein, the first area is provided with a lithium supplementing layer 15, and after electrochemical reaction, the first area has an bright area and a dark area with reference to the description of the lithium supplementing layer arranged on the surface of the first anode active layer; the second area is not provided with a lithium supplementing layer, and after electrochemical reaction, the second area is a dark area.

The first orthographic projection refers to a projection formed by irradiating the second region 131 with incident light in a direction perpendicular to the first functional surface. The first orthographic projection and the tab region 111 at least partially overlap, which may be understood that the first orthographic projection and the tab region 111 may completely overlap or partially overlap. The first orthographic projection at least partially coincides with the tab region 111 means that the second region 131 is at least partially disposed opposite the tab region 111.

The negative electrode plate provided by the utility model comprises the lithium supplementing layer 15, so that lithium can be supplemented for the negative electrode plate 1 in the charging and discharging process of the battery, and the first effect of the negative electrode plate 1 is effectively improved. Further, the second region 131 is not provided on the surface of the second negative electrode active layer 13 opposite to the tab region 111, so that lithium precipitation caused by excessive lithium supplement in the tab region 111 can be avoided, and the cycle performance of the battery can be improved.

During the charge and discharge of the battery, the tab region 111 is likely to generate a lithium precipitation phenomenon, and the size of the tab 14 affects the range of lithium precipitation. In some embodiments of the present utility model, when the length L2 of the second region 131 and the length L1 of the tab 14 satisfy: when l2= (1.1 to 4.0) ×l1, lithium precipitation of the negative electrode sheet 1 can be avoided to the greatest extent on the premise of sufficiently supplementing lithium to the negative electrode sheet 1, and cycle performance of the battery can be improved.

In some embodiments of the present utility model, the width W2 of the second region 131 and the width W0 of the negative electrode current collector 11 satisfy: w2= (0.05 to 0.7) w0.

It is understood that the second functional surface is entirely covered with the second anode active layer 13, and the surface of the second anode active layer 13 remote from the anode current collector 11 includes a first region where the lithium supplementing layer 15 is disposed and a second region 131 where the lithium supplementing layer 15 is not disposed. When the width of the second region 131 and the width of the negative electrode current collector 11 satisfy the above relationship, the lithium precipitation of the negative electrode sheet 1 can be avoided to the greatest extent on the premise of sufficiently supplementing lithium to the negative electrode sheet 1, and the cycle performance of the battery can be improved.

In some embodiments of the present utility model, the first orthographic projection has a first centerline extending along a first direction, and tab region 111 has a second centerline extending along the first direction;

the minimum distance between the first central line and the second central line is less than or equal to 0.5mm along the second direction, and the first direction and the second direction are mutually perpendicular; and/or the number of the groups of groups,

The first orthographic projection has a third centerline extending in the second direction, and the tab region 111 has a fourth centerline extending in the second direction;

And the minimum distance between the third central line and the fourth central line is less than or equal to 0.5mm along the first direction, and the first direction and the second direction are mutually perpendicular.

The present utility model is not particularly limited as long as the first direction and the second direction are perpendicular to each other. In some embodiments, the first direction may be a length direction (x direction) of the negative electrode current collector, and the second direction may be a width direction (y direction) of the negative electrode current collector.

It is understood that the first orthographic projection is offset from the centerline of the tab region 111 extending in the length direction by 0.5mm or less and/or the first orthographic projection is offset from the centerline of the tab region 111 extending in the width direction by 0.5mm or less. That is, the second region 131 is disposed opposite to the tab region 111, and the deviation between the second region 131 and the tab region 111 in the longitudinal direction or the width direction is not more than 0.5mm. By the arrangement, the lithium precipitation in the tab area 111 can be further avoided, and the cycle performance of the battery is improved.

In some embodiments of the present utility model, the thickness H2 of the negative electrode sheet 1 in the second region 131, the thickness H1 of the negative electrode sheet 1 in the first region, and the thickness H0 of the negative electrode current collector 11 satisfy:

(H2-H0)＝(0.55～1.0)*(H1-H0)。

In the present utility model, the thickness of the negative electrode sheet 1 at the second region 131 is thinner, and the thickness of the negative electrode sheet 1 at the first region (open region) is thicker. In the utility model, the thickness of the negative electrode sheet 1 in the second region 131 refers to the average thickness of the negative electrode sheet 1 at the second region 131 after the battery is fully disassembled; the thickness of the negative electrode sheet 1 in the lithium supplementing region refers to the average thickness of the negative electrode sheet 1 in the first region (open region) after the battery is fully disassembled. When the thickness H1 of the negative electrode sheet 1 in the second region 131 and the thickness H2 of the negative electrode sheet 1 in the first region and the thickness H0 of the negative electrode current collector 11 satisfy the above relationship, the second region 131 can effectively accommodate lithium ions from the positive electrode sheet, thereby avoiding lithium precipitation of the negative electrode sheet, and also enabling the thickness of the electrode assembly to be substantially consistent and avoiding dishing.

Fig. 3 is a side view of an electrode assembly in some embodiments of the utility model. As shown in fig. 1 to 3, a second aspect of the present utility model provides an electrode assembly including the above-described negative electrode sheet 1.

It can be understood that in the present utility model, the electrode assembly having a lamination structure can be obtained by laminating the positive electrode sheet 2 and the negative electrode sheet 1 described above; after the positive electrode sheet 2 and the negative electrode sheet 1 are laminated, the electrode assembly having a wound structure can be obtained by winding the laminate.

The electrode assembly comprises the negative electrode plate 1, so that lithium is not easy to separate out from the negative electrode plate 1 in the charge and discharge process of the battery, and the cycle performance of the battery is improved.

The positive electrode sheet 2 is not particularly limited in the present utility model, and may be a positive electrode sheet 2 commonly used in the art.

In some embodiments of the present utility model, the positive electrode sheet 2 is disposed opposite to the negative electrode sheet 1, and the positive electrode sheet 2 includes a positive electrode body and an insulating layer 21 disposed on at least one functional surface of the positive electrode body;

The second orthographic projection of the insulating layer 21 on the second functional surface coincides at least partially with the second region 131 (the second region is not shown in fig. 3).

In the utility model, the positive electrode body refers to a conventional positive electrode plate, and comprises a positive electrode current collector and a positive electrode active layer arranged on at least one functional surface of the positive electrode current collector. The functional surface of the positive electrode body refers to the surface of the positive electrode active layer that is away from the positive electrode current collector. The insulating layer 21 of the present utility model is provided on the surface of the positive electrode active layer remote from the positive electrode current collector.

In the present utility model, the second orthographic projection refers to a projection formed by irradiating the insulating layer 21 with incident light in a direction perpendicular to the second functional surface. The second orthographic projection may partially overlap the second region 131 or may completely overlap.

The positive plate is further provided with the insulating layer 21 opposite to the second area 131, and the insulating layer 21 can prevent excessive lithium ions of the positive plate 2 from migrating to the negative plate, so that lithium precipitation of the negative plate 1 is further avoided, and the cycle performance of the battery is improved.

In some embodiments of the utility model, the edge of the second region 131 is located within the edge of the second orthographic projection, or the edge of the second region 131 at least partially coincides with the edge of the second orthographic projection.

It can be understood that, when the edge of the second region 131 is located within the edge of the second orthographic projection, the insulating layer 21 completely covers the second region 131 (the area of the insulating layer 21 is larger than that of the second region 131), so that excessive migration of lithium ions of the positive electrode sheet 2 to the negative electrode sheet 1 can be further avoided, and further, lithium precipitation of the negative electrode sheet 1 is avoided.

The edge of the second region 131 at least partially coincides with the edge of the second orthographic projection, comprising: the edge of the second area 131 is completely overlapped with the edge of the second orthographic projection, the shape of the insulating layer 21 is the same as that of the second area, and the area is equal, so that excessive migration of lithium ions of the positive plate 2 to the negative plate 1 can be better avoided under the condition of saving the insulating layer 21; the edge of the second region 131 is overlapped with the edge part of the second orthographic projection, the rest edge of the second region 131 is positioned in the edge of the second orthographic projection, the area of the insulating layer 21 is larger than that of the second region 131, excessive migration of lithium ions of the positive plate 2 to the negative plate 1 can be further avoided, and further lithium precipitation of the negative plate 1 is avoided; the edge of the second region 131 is overlapped with the edge part of the second orthographic projection, the rest edge of the second region 131 is positioned outside the edge of the second orthographic projection, the area of the insulating layer 21 is smaller than that of the second region 131, and excessive migration of lithium ions of the positive electrode sheet 2 to the negative electrode sheet 1 can be avoided.

In some embodiments of the present utility model, when the thickness of the insulating layer 21 is 10 to 30 μm, it is possible to improve the flatness of the region after formation of the battery, and it is possible to prevent the gap between the insulating layer edge positive electrode sheet and the negative electrode sheet from increasing, improving the cycle performance of the battery.

In some embodiments of the present utility model, the tab region is formed by recessing the first negative electrode active layer in the direction of the negative electrode current collector, and the tab is disposed in the recessing.

It can be understood that the first negative electrode active layer is recessed towards the direction of the negative electrode current collector to form a tab area, and the tab is arranged in the recess formed by the first negative electrode active layer, so that lithium precipitation of the negative electrode sheet can be avoided under the condition of supplementing lithium for the negative electrode sheet, and the cycle performance of the battery is improved.

A third aspect of the present utility model provides a battery comprising the electrode assembly described above.

It will be appreciated that the battery of the present utility model can be obtained by placing the above-described electrode assembly in an outer package, and injecting an electrolyte into the outer package.

The battery of the present utility model has excellent cycle performance due to the inclusion of the electrode assembly as described above.

The technical scheme of the utility model will be further described below with reference to specific examples.

Example 1

The battery of this example was prepared by a method comprising the steps of:

1) Negative plate

As shown in fig. 1 and 2, a first negative electrode active layer is arranged on a first functional surface of a negative electrode current collector, a part of the first negative electrode active layer on the first functional surface is cleaned to obtain a tab area, and a tab is welded in the tab area;

A second negative electrode active layer is arranged on the second functional surface of the negative electrode current collector, a lithium supplementing layer (a first area) is arranged on the surface, far away from the negative electrode current collector, of the second negative electrode active layer, the area, far away from the negative electrode current collector, of the second negative electrode active layer, where the lithium supplementing layer is not arranged, is a second area, and the first orthographic projection of the second area on the first functional surface is overlapped with the lug area;

Wherein the negative electrode current collector is copper foil, and the thickness of the copper foil is 6 mu m; the length of the tab is 6mm; the second region has a length of 9mm and a width of 22mm;

The first negative electrode active layer and the second negative electrode active layer respectively comprise silicon-doped graphite, a binder SBR, a conductive agent Super-p and a dispersing agent CMC, wherein the mass ratio of the silicon-doped graphite to the binder to the conductive agent to the stabilizing agent is 96.4:2.9:0.25:0.45;

the lithium supplementing layer is a lithium foil.

2) Positive plate

The positive plate comprises a positive body and insulating layers arranged on two surfaces of the positive body, wherein the positive body comprises a positive current collector and positive active layers arranged on two functional surfaces of the positive current collector;

The positive electrode current collector is aluminum foil, the positive electrode active layer comprises lithium cobaltate, conductive agent acetylene black and binder PVDF, and the mass ratio of the lithium cobaltate, the conductive agent and the binder is 98.5:0.7:0.8;

the insulating layer includes the basic material layer (PET layer) and the glue layer (acrylic acid layer) of range upon range of setting, and the length L3 of insulating layer is 12mm, and the width of insulating layer is 24mm, and the thickness of insulating layer is 16um.

3) Battery cell

Laminating the negative electrode plate, the diaphragm and the positive electrode plate in the step 1) and the step 2) to enable the second orthographic projection of the insulating layer on the second functional surface to be overlapped with the second area; then, winding to obtain an electrode assembly, placing the electrode assembly in an aluminum plastic film, and injecting electrolyte into the aluminum plastic film to obtain a battery;

wherein the electrolyte is a commercial electrolyte.

The battery of this example was subjected to full-charge disassembly, and the thickness of the negative electrode sheet was measured, with the thickness of the negative electrode sheet in the second region being 60 μm, and the thickness of the negative electrode sheet in the lithium supplementing region being 83 μm.

Example 2

The battery of this example was prepared in substantially the same manner as in example 1, except that: in step 2), the positive electrode sheet does not contain an insulating layer.

Example 3

The battery of this example was prepared in substantially the same manner as in example 1, except that: in the step 1), the length of the second area is 60mm, the length of the tab is 6mm, and the length ratio of the second area to the tab is 10:1.

Example 4

The battery of this example was prepared in substantially the same manner as in example 1, except that: in the step 1), the width of the second area of the negative electrode sheet is 60mm, and the width of the negative electrode sheet is 60mm.

Example 5

The battery of this example was prepared in substantially the same manner as in example 1, except that: in step 2), the thickness of the insulating layer was 50. Mu.m.

Comparative example 1

The battery of this comparative example was prepared in substantially the same manner as in example 1, except that:

in step 1), the second negative electrode active layer is provided with a lithium supplementing layer (excluding the second region) on the surface far away from the negative electrode current collector.

Comparative example 2

The battery of this comparative example was prepared in substantially the same manner as in comparative example 1, except that:

in step 2), the positive electrode sheet does not contain an insulating layer.

Performance testing

The following performance tests were performed on the batteries of examples and comparative examples, and the results are shown in table 1;

1. Performing charge-discharge cycle test on the battery by using 1C/1C to obtain initial discharge capacity of the battery and discharge capacity after 800 times of cycle, and calculating the capacity retention rate; obtaining the initial thickness of the battery and the thickness after 800 times of circulation, and calculating the thickness expansion rate;

the first discharge capacity and the first charge capacity of the battery were obtained, and the first effect was calculated, first effect=first discharge capacity/first charge capacity.

2. Energy density

Energy density = battery capacity platform voltage/volume of battery

TABLE 1

	Capacity retention/%	Expansion ratio of thickness/%	Energy density/Wh/L	First effect/%
					Example 1	89.4％	12.1％	764	91.75％
Example 2	89.1％	12.9％	761	91.64％
					Example 3	88.7％	13.9％	758	89.5％
Example 4	88.1％	13.4％	749	89.65％
					Example 5	83.1％	14.5％	743	91.23％
Comparative example 1	82.1％	16.8％	737	87.7％
					Comparative example 2	81.9％	17.1％	739	88.1％

As can be seen from table 1, the battery of the example of the present utility model has excellent cycle capacity retention and a low thickness expansion rate.

In this specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. The foregoing is merely illustrative of the preferred embodiments of the present utility model, and is not intended to limit the scope of the present utility model. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model are included in the protection scope of the present utility model.

Claims (10)

1. A negative electrode sheet, characterized by comprising a negative electrode current collector having a first functional surface and a second functional surface disposed opposite to each other;

The first functional surface is provided with a lug area and an active layer area which are connected with each other, the lug area is provided with a lug, the active layer area is provided with a first negative electrode active layer, and the surface of the first negative electrode active layer, which is far away from the negative electrode current collector, is provided with an exposed area and a dark area;

The surface of the second functional surface is provided with a second negative electrode active layer, the surface of the second negative electrode active layer, which is far away from the negative electrode current collector, comprises a first area and a second area which are mutually connected, the first area is provided with an bright area and a dark area, and the second area is a dark area;

The first orthographic projection of the second area on the first functional surface is at least partially overlapped with the tab area.

2. The negative electrode tab according to claim 1, wherein a length L2 of the second region and a length L1 of the tab satisfy: l2= (1.1 to 4.0) L1.

3. The anode sheet according to claim 1 or 2, wherein a width W2 of the second region and a width W0 of the anode current collector satisfy: w2= (0.05 to 0.7) w0.

4. The negative electrode sheet according to claim 1 or 2, wherein the first orthographic projection has a first center line extending in a first direction, and the tab region has a second center line extending in the first direction;

The minimum distance between the first central line and the second central line is less than or equal to 0.5mm along the second direction, and the first direction and the second direction are mutually perpendicular; and/or the number of the groups of groups,

The first orthographic projection has a third centerline extending in a second direction, and the tab region has a fourth centerline extending in the second direction;

along the first direction, the minimum distance between the third central line and the fourth central line is less than or equal to 0.5mm; the first direction and the second direction are perpendicular to each other.

5. The negative electrode sheet according to claim 4, wherein a thickness H2 of the negative electrode sheet in the second region, a thickness H1 of the negative electrode sheet in the first region, and a thickness H0 of the negative electrode current collector satisfy:

(H2-H0)＝(0.55～1.0)*(H1-H0)。

6. An electrode assembly comprising the negative electrode sheet of any one of claims 1 to 5.

7. The electrode assembly of claim 6, further comprising a positive electrode sheet disposed opposite the negative electrode sheet, the positive electrode sheet comprising a positive electrode body and an insulating layer disposed on at least one functional surface of the positive electrode body;

A second orthographic projection of the insulating layer on the second functional surface is at least partially coincident with the second region.

8. The electrode assembly of claim 7, wherein an edge of the second region is located within an edge of the second orthographic projection or at least partially coincides with an edge of the second orthographic projection.

9. The electrode assembly according to claim 8, wherein the tab region is formed by recessing the first anode active layer in the direction of the anode current collector, the tab being disposed in the recessing.

10. A battery comprising an electrode assembly according to any one of claims 6-9.