CN117276468B

CN117276468B - Negative electrode plate, battery and electricity utilization device

Info

Publication number: CN117276468B
Application number: CN202311570632.7A
Authority: CN
Inventors: 黄显; 刘成勇; 葛销明; 蔡晓岚; 仲宁
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-11-23
Filing date: 2023-11-23
Publication date: 2024-04-12
Anticipated expiration: 2043-11-23
Also published as: CN117276468A

Abstract

The application relates to the field of chargeable and dischargeable batteries and provides a negative electrode plate, a battery and an electric device, wherein the negative electrode plate comprises an alkali metal layer and a negative electrode current collector, and the alkali metal layer comprises two sides which are opposite to each other along the thickness direction of the negative electrode plate; the negative electrode current collector is arranged on at least one of the two sides, comprises a plurality of through holes penetrating through the negative electrode current collector along the thickness direction, and is arranged opposite to a part of the alkali metal layer. The cycle life of the battery of the present application can be improved.

Description

Negative electrode plate, battery and electricity utilization device

Technical Field

The application relates to the field of chargeable and dischargeable batteries, in particular to a negative electrode plate, a battery and an electric device.

Background

The battery has characteristics of high capacity, long life, and the like, and thus is widely used in electronic devices such as mobile phones, notebook computers, battery cars, electric automobiles, electric airplanes, electric ships, electric toy automobiles, electric toy ships, electric toy airplanes, electric tools, and the like. As batteries have made great progress, higher demands are being made on the performance of the batteries. In order to improve the performance of the battery, the negative electrode plate in the battery is generally optimized and improved.

However, the cycle life of the battery is still poor when the negative electrode tab is applied to a battery cell.

Disclosure of Invention

The application provides a negative pole piece, battery and power consumption device, the cycle life of the battery of this application can obtain promoting.

In a first aspect, embodiments of the present application provide a negative electrode tab including an alkali metal layer and a negative electrode current collector, the alkali metal layer including two sides opposite to each other in a thickness direction of the negative electrode tab; the negative electrode current collector is arranged on at least one of the two sides, comprises a plurality of through holes penetrating through the negative electrode current collector along the thickness direction, and is arranged opposite to a part of the alkali metal layer.

Therefore, the arrangement of the through holes can reduce the weight of the negative electrode current collector, and is beneficial to improving the energy density of the alkali metal battery; the plurality of through holes can also expose part of the surface of the alkali metal layer, so that the alkali metal layer is utilized, alkali metal ions lost in a battery system can be supplemented, and the cycle life of the alkali metal battery can be prolonged.

In some embodiments, the negative electrode current collector includes a first current collector disposed at one of both sides and a second current collector, and a portion of the plurality of through holes includes a plurality of first through holes penetrating the first current collector in a thickness direction; the second current collector is arranged on the other side of the two sides, and the other part of the plurality of through holes comprise a plurality of second through holes penetrating through the second current collector in the thickness direction.

From this, first through-hole can even electric field in this application embodiment to make one side of alkali metal layer can evenly show the surface, be favorable to inducing alkali metal uniform deposition to distribute in one side of negative pole piece, reduce the risk that the negative pole piece was locally precipitated lithium dendrite, improve the free service reliability of battery. The second through hole can be used for uniformly exposing the surface of the other side of the alkali metal layer, so that uniform deposition of alkali metal on the other side of the negative electrode plate is induced, the risk of local precipitation of lithium dendrite of the negative electrode plate is reduced, and the use reliability of the battery cell is improved.

In some embodiments, the first through holes and the second through holes are alternately arranged along a first direction, the first direction being perpendicular to the thickness direction. The first through holes and the second through holes are alternately arranged along the first direction, so that the stress born by the whole alkali metal layer can be relaxed, the structural stability of the alkali metal layer is improved, and the structural stability of the negative electrode plate is improved.

In some embodiments, the first through hole and the second through hole are disposed opposite to each other in the thickness direction. The first through hole and the second through hole are oppositely arranged, so that the positions of alkali metals deposited on the negative electrode plate are basically the same.

In some embodiments, the alkali metal layer includes a body portion and a connection portion connected to each other in a thickness direction, the negative electrode current collector is disposed on the body portion, and the connection portion protrudes from the body portion in the thickness direction and into the through hole. The connecting part is arranged opposite to the through hole to expose the surface of the connecting part, which is favorable for inducing alkali metal ions to form alkali metal and deposit on the connecting part.

In some embodiments, the edge of the negative electrode current collector in the thickness direction exceeds the edge of the connection portion in the thickness direction. When the alkali metal is deposited to the negative electrode plate, the alkali metal can be deposited in the through hole, so that the alkali metal is not easy to form metal dendrite to puncture the isolating film, and meanwhile, the thickness expansion of the battery cell is slowed down, and the use reliability of the battery cell is improved.

In some embodiments, the plurality of through holes are uniformly distributed, and the plurality of through holes can be capable of uniform electric field, facilitating uniform deposition of alkali metal.

In some embodiments, the percentage of area of the plurality of through holes is 10% to 70% based on the cross-sectional area of the negative current collector parallel to the first direction; optionally 20% to 60%, wherein the first direction is perpendicular to the thickness direction. When the area percentage of the through holes is in the range, on the basis of improving the uniform deposition capability of alkali metal, the oxidation resistance of the negative electrode plate can be further improved, the quality of the negative electrode plate is reduced, and the energy density of the battery cell is improved.

In some embodiments, the surface roughness Ra of the negative electrode current collector satisfies: ra is more than or equal to 0.2 μm and less than or equal to 1 μm. When the surface roughness Ra is in the above range, the negative electrode current collector and the alkali metal layer are more tightly combined, and the connection of the two is more stable; and the negative current collector itself can also induce alkali ions to form alkali metal deposits on the surface of the negative current collector.

In some embodiments, the surface roughness Rz of the negative electrode current collector satisfies: rz is less than or equal to 1.5 mu m and less than or equal to 4 mu m. When the surface roughness Rz is in the above range, the combination of the negative electrode current collector and the alkali metal layer is tighter, and the connection of the negative electrode current collector and the alkali metal layer is more stable; and the negative current collector itself can also induce alkali ions to form alkali metal deposits on the surface of the negative current collector.

In some embodiments, the single-sided negative electrode current collector has an average thickness of 4 μm to 20 μm. When the average thickness of the negative electrode current collector is in the range, the overall strength of the negative electrode plate is improved.

In some embodiments, the alkali metal layer has an average thickness of 5 μm to 100 μm. When the average thickness of the alkali metal layer is in the range, the overall strength of the negative electrode plate is improved, and alkali metal ions can be supplemented for the system.

In some embodiments, the negative current collector comprises a metallic material. The metal material has better conductivity and smaller resistance, and is beneficial to improving the conductivity of the negative electrode plate.

In some embodiments, the metallic material comprises at least one of copper, nickel, and titanium.

In some embodiments, the alkali metal layer comprises at least one of lithium metal and sodium metal; optionally, the alkali metal layer comprises lithium metal. The theoretical gram capacity of lithium metal is relatively high, the lithium metal has relatively low density and negative electrode potential, and the lithium metal serving as the negative electrode active material can remarkably improve the energy density of the battery cell.

In a second aspect, the present application also proposes a battery comprising a negative electrode tab as in any of the embodiments of the first aspect of the present application.

In a third aspect, the present application further proposes an electrical device comprising a battery according to any of the embodiments of the third aspect of the present application.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and that other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic view of an embodiment of a negative electrode tab of the present application.

Fig. 2 is a schematic cross-sectional view of the negative electrode tab of fig. 1 taken along line A-A.

Fig. 3 is another schematic cross-sectional view of the negative electrode tab of fig. 1 taken along line A-A.

Fig. 4 is a further schematic cross-sectional view of the negative electrode tab of fig. 1 taken along line A-A.

Fig. 5 is a further schematic cross-sectional view of the negative electrode tab of fig. 1 taken along line A-A.

Fig. 6 is a further schematic cross-sectional view of the negative electrode tab of fig. 1 taken along line A-A.

Fig. 7 is a further schematic cross-sectional view of the negative electrode tab of fig. 1 taken along line A-A.

Fig. 8 is a schematic view of an embodiment of an electrode assembly in a battery cell of the present application.

Fig. 9 is a schematic diagram of an embodiment of a battery cell of the present application.

Fig. 10 is an exploded schematic view of an embodiment of the battery cell of fig. 9.

Fig. 11 is a schematic view of an embodiment of a battery module of the present application.

Fig. 12 is a schematic view of an embodiment of a battery pack of the present application.

Fig. 13 is an exploded schematic view of the embodiment of the battery pack shown in fig. 12.

Fig. 14 is a schematic diagram of an embodiment of an electrical device including a battery cell of the present application as a power source.

The figures are not necessarily to scale.

The reference numerals are explained as follows:

X, thickness direction; y, first direction;

1. a battery pack; 2. an upper case; 3. a lower box body; 4. a battery module;

5. a battery cell; 51. a housing; 52. an electrode assembly;

53. a cover plate;

6. an electric device;

7. a negative electrode plate;

71. an alkali metal layer; 711. a main body portion; 712. a connection part; 713. a first side; 714. a second side;

72. a negative electrode current collector; 720. a through hole; 721. a first current collector; 7211. a first through hole; 722. a second current collector; 7222. a second through hole;

73. a negative electrode tab;

8. a positive electrode sheet;

9. and a separation film.

Detailed Description

Hereinafter, embodiments of the negative electrode tab, the battery, and the electric device of the present application are specifically disclosed with reference to the drawings as appropriate. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.

The "range" disclosed herein is defined in terms of lower and upper limits, with a given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.

All embodiments and alternative embodiments of the present application may be combined with each other to form new solutions, unless specifically stated otherwise.

All technical features and optional technical features of the present application may be combined with each other to form new technical solutions, unless specified otherwise.

All steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise indicated. For example, the method may include steps (a) and (b), and the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, it is mentioned that the method may further comprise step (c), meaning that step (c) may be added to the method in any order, e.g. the method may comprise steps (a), (b) and (c), may also comprise steps (a), (c) and (b), may also comprise steps (c), (a) and (b), etc.

The battery cell includes an electrode assembly and an electrolyte, the positive electrode sheet including a positive electrode film layer containing a positive electrode active material, the positive electrode active material being a donor of active ions such as lithium ions provided by the battery cell, the negative electrode sheet including a negative electrode film layer containing a negative electrode active material, the negative electrode active material being an acceptor of lithium ions, and the electrolyte providing a migration path of the active ions between the positive electrode sheet and the negative electrode sheet.

Since the theoretical gram capacity of alkali metal is relatively high and has a relatively low density and a negative electrode potential, the use of alkali metal as the negative electrode active material can significantly increase the energy density of the battery cell. However, the battery cells have the loss of alkali metal ions during the cycle, so that the cycle life of the battery cells is shortened.

In view of the above, embodiments of the present application provide a negative electrode tab including an alkali metal layer and a negative electrode current collector disposed on at least one side of the alkali metal layer, the negative electrode current collector including a plurality of through holes penetrating through the negative electrode current collector in a thickness direction of the negative electrode tab, and the plurality of through holes being disposed opposite to a portion of the alkali metal layer. The arrangement of the through holes can reduce the weight of the negative current collector, and is beneficial to improving the energy density of the alkali metal battery; the plurality of through holes can also expose part of the surface of the alkali metal layer, so that the alkali metal layer is utilized, alkali metal ions lost in a battery system can be supplemented, and the cycle life of the alkali metal battery can be prolonged; further, the through holes are uniformly distributed, an electric field can be uniformly distributed, part of the surface of the alkali metal layer is exposed, the exposed part is uniformly distributed, the alkali metal is uniformly deposited and distributed on the surface of the negative electrode plate, the risk of locally precipitating metal dendrites of the negative electrode plate is reduced, and the use reliability of the battery cell is improved. The following describes the technical scheme of the present application in detail.

Negative pole piece

In a first aspect, embodiments of the present application provide a negative electrode tab.

As shown in fig. 1 and 2, the negative electrode tab 7 includes an alkali metal layer 71 and a negative electrode current collector 72 provided on at least one of the two sides, the alkali metal layer 71 includes two sides opposite to each other in a thickness direction X of the negative electrode tab 7, the negative electrode current collector 72 includes a plurality of through holes 720 penetrating the negative electrode current collector 72 in the thickness direction X, and the plurality of through holes 720 are provided opposite to a part of the alkali metal layer 71.

The alkali metal layer 71 includes two sides opposite to each other in the thickness direction X of the anode tab 7, and for the sake of more clear explanation of the structure of the anode tab 7, the two sides of the alkali metal layer 71 are defined as a first side 713 and a second side 714, respectively. At least one of both sides of the alkali metal layer 71 may be provided with a negative electrode current collector 72.

For example, as shown in fig. 2, the negative electrode current collector 72 is disposed on one side of the alkali metal layer 71, in which case the negative electrode current collector 72 may be disposed on the first side 713 of the alkali metal layer 71, and a portion of the first side 713 of the alkali metal layer 71 disposed opposite to the through hole 720 may be exposed, so that the metal in the alkali metal layer 71 may be contacted with the electrolyte through the through hole 720 during the cycle to become ions, thereby being utilized; the portion of the first side 713 that is not disposed opposite to the through hole 720 is covered and blocked by the solid portion of the negative electrode current collector 72; the second side 714 of the alkali metal layer 71 is not covered by the negative current collector 72, and the whole surface of the second side is contacted with electrolyte and the like, so that alkali metal in the alkali metal layer 71 can be utilized, alkali metal ions lost in a battery system can be supplemented, and the cycle life of an alkali metal battery can be prolonged. The solid portion of the negative electrode current collector 72 may be considered as a portion of the negative electrode current collector 72 that does not include the through-holes 720, for example, the negative electrode current collector 72 includes a current collecting body and the through-holes 720, the through-holes 720 being distributed in the current collecting body.

As another example, as shown in fig. 3, the negative electrode current collector 72 is disposed on both sides of the alkali metal layer 71, in which case, the negative electrode current collector 72 may be disposed on the first side 713 and the second side 714 of the alkali metal layer 71, and a portion of the first side 713 of the alkali metal layer 71 opposite to the through hole 720 may be exposed, so that the metal in the alkali metal layer 71 may contact the electrolyte through the through hole 720 during the circulation process and become ions, thereby being utilized, so that the alkali metal in the alkali metal layer 71 may be utilized, and alkali metal ions lost in the battery system may be replenished, thereby being beneficial to improving the cycle life of the alkali metal battery; a portion of the first side 713, which is not disposed opposite to the through hole 720, is covered and shielded by a solid portion of the negative electrode current collector 72; the portion of the second side 714 of the alkali metal layer 71 opposite the through hole 720 can be exposed, so that the metal in the alkali metal layer 71 can contact the electrolyte in the circulation process through hole 720 and become ions to be utilized; the portion of the second side 714 that is not disposed opposite the through hole 720 is covered and shielded by the solid portion of the negative electrode current collector 72.

The negative current collector 72 includes a plurality of through holes 720, and the plurality of through holes 720 are uniformly distributed, which may mean that a distance between two adjacent through holes 720 among the plurality of through holes 720 is a constant value, for example, the plurality of through holes 720 includes four through holes 720, which are a first through hole 720, a second through hole 720, a third through hole 720, and a fourth through hole 720, respectively, and a distance between the first through hole 720 and the second through hole 720 is the same as a distance between the second through hole 720 and the third through hole 720, and a distance between the third through hole 720 and the fourth through hole 720 is the same. Optionally, the plurality of vias 720 are distributed in an array.

The measurement of the distance may be obtained by measuring the center point of the adjacent through holes 720, for example, when the through holes 720 are circular holes, the distance between the adjacent through holes 720 is the distance between the centers of the adjacent circular holes. For example, when the through holes 720 are square holes, the distance between two adjacent through holes 720 is the distance between the center points of the two adjacent square holes.

The cross-sectional shape of the through hole 720 parallel to the first direction Y may be a regular geometric shape or an irregular geometric shape, for example, the cross-sectional shape may be a circle, an ellipse, a triangle, a quadrangle, a pentagon, a hexagon, or the like.

Thus, in the embodiments of the present application. The plurality of through holes 720 can reduce the weight of the negative current collector 72, which is beneficial to improving the energy density of the alkali metal cell; the plurality of through holes 720 can also expose part of the surface of the alkali metal layer 71, so that the alkali metal layer 71 is utilized, lithium ions lost in a battery system can be supplemented, and the cycle life of the lithium metal battery can be prolonged

Further, the plurality of through holes 720 of the negative current collector 72 are uniformly distributed, for example, distributed in an array, the plurality of through holes 720 expose part of the alkali metal layer 71, and the exposed areas are uniformly distributed, so that uniform deposition distribution of alkali metal on the surface of the negative electrode plate 7 is induced, the risk of locally precipitating metal dendrites of the negative electrode plate 7 is reduced, and the use reliability of the battery cell is improved. Since the alkali metal layer 71 has activity, there may be a risk of oxidation during the contact with air, and the negative current collector 72 in the embodiment of the present application covers part of the structure of the alkali metal layer 71, the contact area between the alkali metal layer 71 and air is reduced, thereby reducing the oxidation area, reducing the risk of oxidation of the alkali metal layer 71, and improving the stability and storage life of the negative electrode tab 7 during the storage process. And the negative current collector 72 is of a hollow structure, so that the mass is lighter, and the energy density of the battery cell is improved.

In some embodiments, the aperture of the through hole 720 is 0.1mm to 3mm; optionally 0.7mm to 1.5mm.

When the through hole 720 is a round hole, the aperture is the diameter of the round hole; when the through hole 720 is a non-circular hole, the longest diameter of the through hole 720 may be used as the aperture of the through hole 720. When the aperture of the through hole 720 is in the above range, the surface of the exposed alkali metal layer 71 is relatively small, the deposited alkali metal at the exposed alkali metal layer 71 is relatively small, the risk of forming dendrites locally by the alkali metal is reduced, the use reliability of the battery cell is improved, and meanwhile, the small aperture is not easy to deform in the process of processing the composite lithium metal, so that the consistency of the composite process is ensured.

Illustratively, the aperture of the through-hole 720 may be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 1mm, 1.2mm, 1.3mm, 1.5mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.3mm, 2.5mm, 2.6mm, 2.8mm, 3mm, or a range of any two of the numerical compositions mentioned above.

In some embodiments, the spacing between adjacent two through holes 720 is 0.2mm to 5mm; optionally 1mm to 2mm. When the interval between the adjacent two through holes 720 is within the above range, the interval between the two through holes 720 is relatively small, which is advantageous in maintaining the tensile property of the copper foil.

Illustratively, the spacing between two adjacent through holes 720 may be 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 1mm, 1.2mm, 1.3mm, 1.5mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.3mm, 2.5mm, 2.6mm, 2.8mm, 3mm, 3.2mm, 3.5mm, 3.6mm, 3.8mm, 4mm, 4.2mm, 4.5mm, 4.8mm, 5mm, or a range of any two of the numerical values mentioned above.

In some embodiments, the alkali metal layer 71 includes at least one of lithium metal and sodium metal. For example, the alkali metal layer 71 includes lithium metal, i.e., the alkali metal layer 71 is a lithium metal layer. Alternatively, the alkali metal layer 71 comprises sodium metal, i.e. the alkali metal layer 71 is a sodium metal layer. Alternatively, the alkali metal layer 71 includes lithium metal and sodium metal, and the alkali metal layer 71 is a lithium sodium metal layer. The theoretical gram capacity of lithium metal is relatively high, the lithium metal has relatively low density and negative electrode potential, and the lithium metal serving as the negative electrode active material can remarkably improve the energy density of the battery cell.

As shown in fig. 4, in some embodiments, negative electrode current collectors 72 are disposed on both sides of alkali metal layer 71; specifically, the negative electrode current collector 72 includes a first current collector 721 and a second current collector 722, the first current collector 721 being disposed at one of both sides, and a portion of the plurality of through holes 720 including a plurality of first through holes 7211 penetrating the first current collector 721 in the thickness direction X; the second current collector 722 is disposed at the other of the two sides, and another part of the plurality of through holes 720 includes a plurality of second through holes 7222 penetrating the second current collector 722 in the thickness direction X.

For a clearer illustration of the structure of the negative electrode tab 7, it may be defined that a first current collector 721 is arranged on the first side 713 of the alkali metal layer 71 and a second current collector 722 is arranged on the second side 714 of the alkali metal layer 71.

Since the first through-hole 7211 penetrates the first current collector 721 in the thickness direction X, the alkali metal layer 71 disposed opposite to the first through-hole 7211 exposes the surface thereof, facilitating the deposition of alkali metal ions at the portion to form alkali metal; and because the first through holes 7211 are uniformly arranged, the electric field can be uniform, the surface of the alkali metal layer 71 can be uniformly exposed, the alkali metal can be induced to be uniformly deposited and distributed on the first side 713 of the negative electrode plate 7, the risk of locally precipitating lithium dendrites of the negative electrode plate 7 is reduced, and the use reliability of the battery cell is improved.

Since the second through-holes 7222 penetrate the second current collector 722 in the thickness direction X, the alkali metal layer 71 disposed opposite to the second through-holes 7222 exposes the surface thereof, facilitating the deposition of alkali metal ions at the portion to form alkali metal; and because the second through holes 7222 are uniformly arranged, the electric field can be uniform, the surface of the alkali metal layer 71 can be uniformly exposed, the alkali metal can be induced to be uniformly deposited and distributed on the second side 714 of the negative electrode plate 7, the risk of locally precipitating lithium dendrites of the negative electrode plate 7 is reduced, and the use reliability of the battery cell is improved.

In the embodiment of the present application, the cross-sectional shape of the first through hole 7211 parallel to the first direction Y may be the same as or different from the cross-sectional shape of the second through hole 7222 parallel to the second direction Y; for example, the cross-sectional shape of the first through hole 7211 is circular, and the cross-sectional shape of the second through hole 7222 is quadrangular; for another example, the first through hole 7211 has a circular cross-sectional shape, and the second through hole 7222 has a circular cross-sectional shape. The first direction Y is perpendicular to the thickness direction X and can be parallel to the width direction or the length direction of the negative electrode sheet 7

In some embodiments, the alkali metal layer 71 may include a body part 711 and a connection part 712 connected to each other in the thickness direction X, the negative electrode current collector 72 being disposed on the body part 711, the connection part 712 being located within the through hole 720.

The body portion 711 and the connection portion 712 are connected to each other, and both may be integrally constructed, and the connection portion 712 may be considered to protrude from the body portion 711 in the thickness direction X and into the through hole 720. In other words, the connection portion 712 is disposed opposite to the through hole 720 to expose the surface thereof, which is beneficial to induce alkali metal ions to form alkali metal and deposit on the connection portion 712.

When the first current collector 721 and the second current collector 722 are disposed on the alkali metal layer 71, a portion of the alkali metal layer 71 may protrude into the through hole due to the pressing force.

With continued reference to fig. 4, in some embodiments, the connecting portion 712 is located in the through hole 720, the edge of the negative current collector 72 in the thickness direction X exceeds the edge of the connecting portion 712 in the thickness direction X, and when the alkali metal is deposited onto the negative electrode tab 7, the alkali metal can be deposited into the through hole 720, so that the alkali metal is not easy to form a metal dendrite to puncture the isolating film, and meanwhile, the thickness expansion of the battery cell is slowed down, thereby improving the use reliability of the battery cell.

As shown in fig. 5, in some embodiments, a surface of the connection portion 712 facing away from the body portion 711 protrudes toward a direction facing away from the body portion 711. The surface of the connection portion 712 facing away from the main body portion 711 may have an arcuate surface.

Alternatively, the connection portion 712 and the main body portion 711 are smoothly connected, and the connection therebetween is smoother, which is advantageous for alleviating the problem of stress concentration of the alkali metal layer 71, thereby improving the structural stability of the alkali metal layer 71.

As shown in fig. 6, in some embodiments, the surface of the connection portion 712 facing away from the main body portion 711 is flush with the surface of the negative electrode current collector 72. The surface of the connecting portion 712 is flush with the surface of the negative current collector 72, so that the structural strength of the negative electrode tab 7 is higher, and the content of alkali metal in the negative electrode tab 7 is improved.

With continued reference to fig. 6, in some embodiments, the first through holes 7211 and the second through holes 7222 are disposed opposite in the thickness direction X.

The first and second through holes 7211 and 7222 are oppositely disposed such that the alkali metal deposited at the first and second sides 713 and 714 is substantially the same.

When the negative electrode current collector 72 is disposed on both sides of the alkali metal layer 71, the alkali metal layer 71 is located between the first current collector 721 and the second current collector 722, and during the lamination of the three layers to form the negative electrode sheet 7, the alkali metal layer 71 may deform, a portion of the alkali metal layer 71 may protrude into the through hole 720 (the connection portion 712 is shown to be located in the through hole 720), for example, in the first through hole 7211 and/or the second through hole 7222, and stress may be accumulated in the interior of the alkali metal layer 71, especially at the deformed connection portion thereof, that is, the stress concentration problem at the connection portion of the main body portion 711 and the connection portion 712 is more remarkable.

As shown in fig. 7, in some embodiments, the first through holes 7211 and the second through holes 7222 are alternately arranged along the first direction Y, so that the stress applied to the entire alkali metal layer 71 can be relaxed, and the structural stability of the alkali metal layer 71 and thus the structural stability of the negative electrode tab 7 can be improved. The first direction Y is perpendicular to the thickness direction X, and may be parallel to the width direction or the length direction of the negative electrode tab 7.

In some embodiments, the percentage of area of the plurality of through holes 720 is 10% to 70% based on the cross-sectional area of the negative electrode current collector 72 parallel to the first direction Y. Alternatively, the area percentage of the plurality of through holes 720 is 20% to 60%.

The percentage of the area of the plurality of through holes 720 is the percentage of the total area of the plurality of through holes 720 occupying the cross-sectional area of the negative electrode current collector 72 parallel to the first direction Y, and may also be understood as the opening ratio of the negative electrode current collector 72, where the opening ratio in the above range, on the basis of improving the uniform deposition ability of the alkali metal, the oxidation resistance of the negative electrode tab 7 can be further improved, the quality of the negative electrode tab 7 can be reduced, and the energy density of the battery cell can be improved.

Illustratively, the area percentage of the plurality of vias 720 may be 10%, 12%, 15%, 16%, 18%, 20%, 23%, 26%, 28%, 30%, 32%, 35%, 36%, 38%, 40%, 42%, 45%, 46%, 48%, 50%, 52%, 53%, 54%, 55%, 56%, 58%, 60%, 62%, 64%, 65%, 66%, 68%, 70% or a range of any two of the foregoing values.

In some embodiments, the negative electrode current collector 72 may be a metal material or a composite current collector. As an example of the metal material, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric material base layer. As an example, the metallic material may include at least one of copper, copper alloy, nickel alloy, titanium alloy, silver, and silver alloy. As an example, the polymeric material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and Polyethylene (PE).

Alternatively, the negative electrode current collector 72 includes a metal material; the metal material has better conductivity and smaller resistance, and is beneficial to improving the conductivity of the negative electrode plate 7.

The negative electrode current collector 72 may be a structure body composed of a mesh structure, a filament structure, or a fibrous structure. That is, the negative electrode current collector 72 may further include a hole structure in addition to the through hole 720. The pore structure may be formed by a process for preparing the negative electrode current collector 72. In this case, the hole structure can contact the alkali metal layer 71 between the first current collector 721 and the second current collector 722 with the electrolyte, and the alkali metal can be deposited in the hole structure and the through holes 720.

In some embodiments, the surface roughness Ra of the negative electrode current collector 72 satisfies: ra is more than or equal to 0.2 μm and less than or equal to 1 μm.

The surface roughness Ra represents the average arithmetic deviation of the profile, specifically the arithmetic average of the absolute value of the profile offset within the sampling length. When the surface roughness Ra is in the above range, the negative electrode current collector 72 and the alkali metal layer 71 are more tightly bonded, and the connection between them is more stable; and the negative electrode current collector 72 itself can induce alkali metal ions to form alkali metal deposits on the surface of the negative electrode current collector 72.

Illustratively, the surface roughness Ra of the negative electrode current collector 72 may be 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, or a range of any two of the numerical compositions described above.

In some embodiments, the surface roughness Rz of the negative electrode current collector 72 satisfies: rz is less than or equal to 1.5 mu m and less than or equal to 4 mu m.

The surface roughness Rz represents the average height of the unevenness, which can reflect the peak-to-valley relief height of the measured surface profile. When the surface roughness Rz is in the above range, the negative electrode current collector 72 and the alkali metal layer 71 are more tightly bonded, and the connection of the two is more stable; and the negative electrode current collector 72 itself can induce alkali metal ions to form alkali metal deposits on the surface of the negative electrode current collector 72.

Illustratively, the surface roughness Rz of the negative electrode current collector 72 may be 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3.0 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, 3.9 μm, 4 μm, or a range of any two of the above numerical values.

In this embodiment, the meaning of the surface roughness Ra and Rz is known in the art, and may be tested by using a device and a method known in the art, for example, a diamond stylus with a tip radius of curvature of about 2 micrometers may be slid along the surface to be tested, the up-down displacement of the diamond stylus is converted into an electrical signal by an electrical length sensor, and after amplification, filtering and calculation, the display instrument indicates the roughness value, or a recorder records the profile curve of the section to be tested, so as to calculate the surface roughness Ra or the surface roughness Rz.

In some embodiments, the tensile strength of negative electrode current collector 72 is greater than or equal to 10MPa; optionally 10MPa to 200MPa.

The negative electrode current collector 72 has high tensile strength, and can improve the structural stability of the negative electrode sheet 7 when being compounded with the alkali metal layer 71.

Illustratively, the tensile strength of the negative electrode current collector 72 may be 10MPa, 12MPa, 13MPa, 14MPa, 15MPa, 16MPa, 18MPa, 20MPa, 22MPa, 25MPa, 26MPa, 28MPa, 30MPa, 32MPa, 35MPa, 38MPa, 40MPa, 42MPa, 45MPa, 50MPa, 52MPa, 55MPa, 60MPa, 62MPa, 68MPa, 70MPa, or a range of any two of the numerical compositions described above.

In this embodiment, the tensile strength is defined as known in the art, and may be tested by using a device and a method known in the art, for example, a tensile tester may be used to obtain a copper mesh sample with a certain width, the sectional area of the copper mesh sample is calculated according to the width and thickness, two ends of the sample are clamped by a tensile machine, stretching is performed at a constant speed such as 1.5mm/min, the tensile force at break is recorded, and the sectional area is divided to obtain the tensile strength of the sample.

In some embodiments, the average thickness of the negative electrode current collector 72 is 4 μm to 20 μm; optionally 8 μm to 12 μm. When the average thickness of the negative electrode current collector 72 is in the above range, it is advantageous to improve the strength of the negative electrode tab 7 as a whole. For example, the average thickness of the negative electrode current collector 72 may be 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or a range of any two of the numerical compositions mentioned above.

The average thickness of the negative electrode current collector 72 is the average thickness of the single-sided negative electrode current collector 72, for example, the negative electrode current collector 72 is disposed on both sides of the alkali metal layer 71, the average thickness of the negative electrode current collector 72 is the average thickness of the first current collector 721 and the second current collector 722, specifically, the average thickness of the single-sided negative electrode current collector 72 is obtained by dividing the sum of the thicknesses of the first current collector 721 and the second current collector 722 by 2.

In some embodiments, the alkali metal layer 71 has an average thickness of 5 μm to 100 μm; optionally 20 μm to 60 μm. When the average thickness of the alkali metal layer 71 is within the above range, the strength of the negative electrode tab 7 as a whole is advantageously improved, and alkali metal ions can be supplied to the system. For example, the average thickness of the alkali metal layer 71 may be 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, or a range of any two of the above numerical values.

The average thickness of the alkali metal layer 71 can be understood as the sum of the average thickness of the body portion 711 and the average thickness of the connecting portion 712. When the connection portions 712 are provided on both sides of the body portion 711, the thickness of the alkali metal layer 71 is the sum of the thickness of the body portion 711 and the thickness of the connection portion 712 by 2 times. When the connection portion 712 is provided on the body portion 711 side, the thickness of the alkali metal layer 71 is the sum of the thickness of the body portion 711 and the thickness of the connection portion 712.

In some embodiments, the negative electrode tab 7 further includes a negative electrode tab 73 connected to the negative electrode current collector 72, where the negative electrode tab 73 may be a solid structure, and may not include a through hole 720 penetrating through itself, and the structural strength of the negative electrode tab 7 is higher, so that the overcurrent area of the negative electrode tab 7 is relatively higher, and the conductivity and welding reliability of the negative electrode tab 7 are improved.

The negative electrode tab 7 does not exclude other additional functional layers than the alkali metal layer 71. For example, in some examples, the anode tab 7 of the present embodiment further includes a conductive undercoat layer (e.g., composed of a conductive agent and a binder) interposed between the anode current collector 72 and the alkali metal layer 71, disposed on the surface of the anode current collector 72. In other examples, the negative electrode tab 7 of the embodiment of the present application further includes a protective layer covering the surface of the negative electrode film layer.

The preparation method of the negative electrode sheet 7 according to the embodiment of the present application may include the steps of:

providing an alkali metal layer 71;

the negative electrode current collector 72 is provided to the alkali metal layer 71, and is combined into the negative electrode tab 7.

In some embodiments, the step of providing the negative current collector 72 to the alkali metal layer 71, and compounding into the negative electrode tab 7 includes:

the negative electrode current collector 72 includes a first current collector 721 and a second current collector 722;

The first current collector 721 is provided to one side of the alkali metal layer 71;

a second current collector 722 is provided to the other side of the alkali metal layer 71, forming a negative electrode tab 7.

Battery cell

In a second aspect, embodiments of the present application provide a battery cell including a negative electrode tab as in any of the embodiments of the first aspect of the present application. The battery cell may be an alkali metal battery.

[ Positive electrode sheet ]

In some embodiments, the battery cell includes a positive electrode tab.

In some embodiments, the positive electrode tab includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has two surfaces opposing in the thickness direction thereof, and the positive electrode film layer is provided on either one or both of the two opposing surfaces of the positive electrode current collector.

When the battery cell of the present application is a lithium metal battery, the positive electrode active material may include, but is not limited to, at least one of lithium-containing transition metal oxides, lithium-containing phosphates, and their respective modifying compounds. Examples of the lithium transition metal oxide may include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate, a composite of lithium iron phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon, and their respective modified compounds.

In some embodiments, to further increase the energy density of the battery cell, the positive electrode active material for a lithium metal battery may include a material having the general formula Li _a Ni _b Co _c M _d O _e A _f At least one of the lithium transition metal oxides and modified compounds thereof. A is more than or equal to 0.8 and less than or equal to 1.2,0.5 and less than or equal to B is less than or equal to 1, c is more than 0 and less than or equal to 1, d is more than 0 and less than or equal to 1, e is more than or equal to 1 and less than or equal to 0 and less than or equal to 1, f is more than or equal to 0 and less than or equal to 1, M comprises at least one of Mn, al, zr, zn, cu, cr, mg, fe, V, ti and B, and A comprises at least one of N, F, S and Cl.

As an example, the positive active material for a lithium metal battery may include LiCoO ₂ 、LiNiO ₂ 、LiMnO ₂ 、LiMn ₂ O ₄ 、LiNi _1/3 Co _1/3 Mn _1/3 O ₂ （NCM333）、LiNi _0.5 Co _0.2 Mn _0.3 O ₂ （NCM523）、LiNi _0.6 Co _0.2 Mn _0.2 O ₂ （NCM622）、LiNi _0.8 Co _0.1 Mn _0.1 O ₂ （NCM811）、LiNi _0.80 Co _0.15 Al _0.05 O ₂ 、LiFePO ₄ 、LiMnPO ₄ At least one of them.

When the battery cell of the present application is a sodium metal battery, the positive electrode active material may include, but is not limited to, at least one of sodium-containing transition metal oxides, polyanionic materials (e.g., phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), prussian blue-based materials.

As an example, the positive electrode active material for a sodium ion battery may include NaFeO ₂ 、NaCoO ₂ 、NaCrO ₂ 、NaMnO ₂ 、NaNiO ₂ 、NaNi _1/2 Ti _1/2 O ₂ 、NaNi _1/2 Mn _1/2 O ₂ 、Na _2/3 Fe _1/3 Mn _2/3 O ₂ 、NaNi _1/3 Co _1/3 Mn _1/3 O ₂ 、NaFePO ₄ 、NaMnPO ₄ 、NaCoPO ₄ Prussian blue material with general formula X _p M’ _q (PO ₄ ) _r O _x Y _3-x At least one of the materials of (a) and (b). In the general formula X _p M’ _q (PO ₄ ) _r O _x Y _3-x Wherein p is more than 0 and less than or equal to 4, q is more than 0 and less than or equal to 2, r is more than or equal to 1 and less than or equal to 3, x is more than or equal to 0 and less than or equal to 2, and X comprises H ⁺ 、Li ⁺ 、Na ⁺ 、K ⁺ And NH ₄ ⁺ M' is a transition metal cation, optionally at least one of V, ti, mn, fe, co, ni, cu and Zn, and Y is a halide anion, optionally at least one of F, cl and Br.

In the present application, the modifying compound of each of the positive electrode active materials may be a doping modification and/or a surface coating modification of the positive electrode active material.

The battery cells may be charged and discharged with the release and consumption of active ions such as Li, and the molar contents of Li are different when the battery cells are discharged to different states. In the list of the positive electrode active materials in the embodiments of the present application, the molar content of Li is the initial state of the material, that is, the state before charging, and the molar content of Li may change after charge and discharge cycles when the positive electrode active material is applied to a battery system.

In the examples of the positive electrode active material according to the present embodiment, the molar content of oxygen O is only a theoretical state value, and the lattice oxygen release causes a change in the molar content of oxygen O, and in practice, the molar content of oxygen O may float.

In some embodiments, the positive electrode film layer further optionally includes a positive electrode conductive agent. The kind of the positive electrode conductive agent is not particularly limited, and the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers as an example. In some embodiments, the mass percent of positive electrode conductive agent is less than or equal to 5% based on the total mass of the positive electrode film layer.

In some embodiments, the positive electrode film layer further optionally includes a positive electrode binder. The kind of the positive electrode binder is not particularly limited in the present application, and the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluoroacrylate-based resin, as an example. In some embodiments, the mass percent of positive electrode binder is less than or equal to 5% based on the total mass of the positive electrode film layer.

In some embodiments, the positive current collector may employ a metal foil or a composite current collector. As an example of the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric material base layer. As an example, the metal material may include at least one of aluminum, aluminum alloy, nickel alloy, titanium alloy, silver, and silver alloy. As an example, the polymeric material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and Polyethylene (PE).

The positive electrode film layer is usually formed by coating positive electrode slurry on a positive electrode current collector, drying and cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring uniformly. The solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.

[ electrolyte ]

In some embodiments, the battery cell further comprises an electrolyte.

In the process of charging and discharging the battery cell, active ions are inserted and separated back and forth between the positive pole piece and the negative pole piece, and the electrolyte plays a role in conducting active ions between the positive pole piece and the negative pole piece. The type of the electrolyte is not particularly limited in the embodiment of the present application, and may be selected according to actual requirements.

The electrolyte includes an electrolyte salt and a solvent. The kinds of the electrolyte salt and the solvent are not particularly limited, and may be selected according to actual requirements.

When the battery cell of the embodiments of the present application is a lithium metal battery, as an example, the electrolyte salt may include, but is not limited to, lithium hexafluorophosphate (LiPF ₆ ) Lithium tetrafluoroborate (LiBF) ₄ ) Lithium perchlorate (LiClO) ₄ ) Lithium hexafluoroarsenate (LiAsF) ₆ ) Lithium bis (fluorosulfonyl) imide (LiLSI), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalato borate (LiDFOB), lithium difluorooxalato borate (LiBOB), lithium difluorophosphate (LiPO) ₂ F ₂ ) At least one of lithium difluorophosphate (LiDFOP) and lithium tetrafluorooxalate phosphate (LiTFOP).

When the battery cell of the embodiments of the present application is a sodium metal battery, as an example, the electrolyte salt may include, but is not limited to, sodium hexafluorophosphate (NaPF ₆ ) Sodium tetrafluoroborate (NaBF) ₄ ) Sodium perchlorate (NaClO) ₄ ) Sodium hexafluoroarsenate (NaAsF) ₆ ) Sodium bis (fluorosulfonyl) imide (NaFSI), sodium bis (trifluoromethanesulfonyl) imide (NaTFSI), sodium (NaTFS) triflate, sodium (NaDFOB) difluorooxalato borate, sodium (NaBOB) dioxaoxalato borate, sodium (NaPO) ₂ F ₂ ) At least one of sodium difluorophosphate (NaDFOP) and sodium tetrafluorooxalate phosphate (NaDFOP).

As an example, the solvent may include, but is not limited to, at least one of Ethylene Carbonate (EC), propylene Carbonate (PC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene Carbonate (BC), fluoroethylene carbonate (FEC), methyl Formate (MF), methyl Acetate (MA), ethyl Acetate (EA), propyl Acetate (PA), methyl Propionate (MP), ethyl Propionate (EP), propyl Propionate (PP), methyl Butyrate (MB), ethyl Butyrate (EB), 1, 4-butyrolactone (GBL), sulfolane (SF), dimethylsulfone (MSM), methylsulfone (EMS), and diethylsulfone (ESE).

In some embodiments, additives are optionally also included in the electrolyte. For example, the additives may include negative electrode film-forming additives, or may include positive electrode film-forming additives, or may include additives that improve certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high temperature performance of the battery, additives that improve the low temperature power performance of the battery, and the like.

[ isolation Membrane ]

In some embodiments, a separator is also included in the battery cell. The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability may be used.

In some embodiments, the material of the isolation film may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.

As shown in fig. 8, in some embodiments, the positive electrode tab 8, the separator 9, and the negative electrode tab 7 may be manufactured into an electrode assembly 52 through a winding process and/or a lamination process. Fig. 8 shows a rolled electrode assembly.

In some embodiments, the battery cell may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte as described above.

In some embodiments, the exterior packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The outer package of the battery cell may also be a pouch, such as a pouch-type pouch. The soft bag can be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT) and polybutylene succinate (PBS).

The shape of the battery cell is not particularly limited in this application, and may be cylindrical, square, or any other shape. Fig. 9 shows a square-structured battery cell 5 as an example.

In some embodiments, the positive electrode tab, the separator, and the negative electrode tab may be manufactured into an electrode assembly through a winding process and/or a lamination process.

In some embodiments, the exterior packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The outer package of the battery cell may also be a pouch, such as a pouch-type pouch. The soft bag can be made of one or more layers of materials, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), polyethylene terephthalate (PET) and polybutylene succinate (PBS), and can also be a metal aluminum layer or an iron layer.

The shape of the battery cell is not particularly limited in this application, and may be cylindrical, square, or any other shape. Fig. 10 shows a square-structured battery cell 5 as an example.

In some embodiments, as shown in fig. 10, the outer package may include a housing 51 and a cover 53. The housing 51 may include a bottom plate and a side plate coupled to the bottom plate, the bottom plate and the side plate enclosing to form a receiving chamber. The housing 51 has an opening communicating with the accommodation chamber, and the cover plate 53 is used to cover the opening to close the accommodation chamber. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into the electrode assembly 52 through a winding process and/or a lamination process. The electrode assembly 52 is packaged in the receiving chamber. The electrolyte is impregnated in the electrode assembly 52. The number of the electrode assemblies 52 included in the battery cell 5 may be one or more, and may be adjusted according to the need.

Methods of making the battery cells of the present application are well known. In some embodiments, the positive electrode tab, separator, negative electrode tab, and electrolyte may be assembled to form a battery cell. As an example, the positive electrode sheet, the separator and the negative electrode sheet may be wound and/or laminated to form an electrode assembly, the electrode assembly is placed in an outer package, dried and then injected with an electrolyte, and the battery cell is obtained through vacuum packaging, standing, formation, shaping and other steps.

In some embodiments of the present application, the battery cells according to the present application may be assembled into a battery module, and the number of the battery cells included in the battery module may be plural, and the specific number may be adjusted according to the application and capacity of the battery module.

Fig. 11 is a schematic view of the battery module 4 as an example. As shown in fig. 11, in the battery module 4, a plurality of battery cells 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, the arrangement may be performed in any other way. The plurality of battery cells 5 may be further fixed by fasteners.

Alternatively, the battery module 4 may further include a housing having an accommodating space in which the plurality of battery cells 5 are accommodated.

In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

Fig. 12 and 13 are schematic views of the battery pack 1 as an example. As shown in fig. 12 and 13, a battery box and a plurality of battery modules 4 provided in the battery box may be included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 is used for covering the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

The battery of the embodiment of the application may include one battery cell or a plurality of battery cells, and in the case where the battery includes a plurality of battery cells, the battery may include a battery module or a battery pack.

Power utilization device

A third aspect of embodiments of the present application provides an electrical device comprising at least one of a battery cell, a battery module, or a battery pack of the present application. The battery cell, the battery module, or the battery pack may be used as a power source of the electric device, and may also be used as an energy storage unit of the electric device. The electric device may be, but is not limited to, a mobile device (e.g., a cellular phone, a notebook computer, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

The power utilization device can select a battery cell, a battery module or a battery pack according to the use requirement.

Fig. 14 is a schematic diagram of the power consumption device 6 as an example. The electric device 6 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. To meet the high power and high energy density requirements of the power consumer 6, a battery pack or battery module may be employed.

As another example, the power consumption device may be a mobile phone, a tablet computer, a notebook computer, or the like. The power utilization device is required to be light and thin, and a battery unit can be used as a power supply.

Examples

The following embodiments more particularly describe the disclosure of the present application, which are for illustrative purposes only, as various modifications and changes within the scope of the disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages and ratios reported in the following embodiments are on a mass basis, and all reagents used in the embodiments are commercially available or synthetically obtained according to conventional methods and can be used directly without further treatment, as well as the instruments used in the embodiments are commercially available.

Example 1

1. Preparation of positive electrode plate

Aluminum foil is used as the positive current collector.

LiCoO as positive electrode active material ₂ Fully stirring and mixing conductive agent carbon black and binder polyvinylidene fluoride (PVDF) in a weight ratio of 97.5:1.4:1.1 in a proper amount of solvent N-methylpyrrolidone NMP to form uniform anode slurry; and uniformly coating the anode slurry on the surface of an anode current collector aluminum foil, and drying and cold pressing to obtain an anode plate.

2. Preparation of negative electrode plate

A porous copper foil with a thickness of 12 μm was used, and the edge of the porous copper foil was left with a non-porous region 5mm to 40mm wide for use as a negative electrode tab.

Pressing metal lithium onto the porous copper foil;

and pressing the other porous copper foil on the lower surface of the metal lithium to prepare the negative electrode plate, wherein the area of the negative electrode plate is 50 mm-40 mm.

3. Isolation film

Porous Polyethylene (PE) film was used as the separator film.

4. Preparation of electrolyte

And (3) in an environment with the water content less than 10ppm, mixing a nonaqueous organic solvent of ethylene carbonate EC and diethyl carbonate DMC according to a volume ratio of 1:1 to obtain an electrolyte solvent, and then mixing lithium hexafluorophosphate as a lithium salt with the mixed solvent to prepare the electrolyte with the lithium salt concentration of 1 mol/L.

5. Preparation of battery cells

Sequentially stacking the positive electrode plate, the isolating film and the negative electrode plate, so that the isolating film is positioned between the positive electrode plate and the negative electrode plate to play a role in isolation, and an electrode assembly is obtained; and placing the electrode assembly in an outer packaging shell, drying, injecting electrolyte, and performing vacuum packaging, standing, formation, shaping and other procedures to obtain the battery.

Comparative example 1

A battery was prepared in a similar manner to example 1, except that the negative electrode tab was prepared by the following steps:

Adopting a non-porous copper foil with the thickness of 8 mu m;

and pressing metal lithium onto the nonporous copper foil to prepare the negative electrode plate.

Example 2

And pressing the metal lithium onto the porous copper foil.

Examples 3-1 and 3-2

A battery was produced in a similar manner to example 1, except that the thickness of the alkali metal layer in the negative electrode tab was adjusted, unlike example 1.

Examples 4-1 and 4-2

A battery was produced in a similar manner to example 1, except that the area percentage of the through-holes in the copper foil in the negative electrode tab was adjusted, unlike example 1.

Examples 5-1 and 5-2

A battery was produced in a similar manner to example 1, except that the surface roughness in the copper foil in the negative electrode tab was adjusted, unlike example 1.

The relevant parameters for the examples and comparative examples are shown in table 1.

Test part

1. And (3) testing the cycle performance of the battery cell:

the ambient temperature was adjusted to 25 ℃, the battery prepared above was charged to 4.3V at 0.5C, then charged to 0.05C at constant voltage, then discharged at a current of 0.5C, cycled to 80% capacity retention, the flow was stopped, and the number of cycles was recorded.

Test results

The test results are shown in Table 1.

TABLE 1

As can be seen from table 1, the battery of comparative example 1 has reduced the cycle life of the lithium metal battery because the copper foil blocks the electrolyte from contacting the lithium metal during the cycle, which affects the replenishment of lithium loss in the negative electrode lithium metal to the positive electrode sheet. In the embodiment of the application, the current collector with the through holes is used as the negative current collector, so that on one hand, the alkali metal layer can be exposed to a part so as to be convenient for being contacted with the electrolyte, the alkali metal layer is utilized, lithium lost in a battery system can be supplemented, and the cycle life of a lithium metal battery is prolonged; on the other hand, the whole weight of the copper foil is reduced through the through hole, so that the energy density of the lithium metal battery is improved.

Although illustrative embodiments have been shown and described, it will be understood by those skilled in the art that the foregoing embodiments are not to be construed as limiting the application and that changes, substitutions and alterations of the embodiments may be made without departing from the spirit, principles and scope of the application.

Claims

1. A negative electrode tab, comprising:

an alkali metal layer including two sides opposite to each other in a thickness direction of the negative electrode tab; and

The negative electrode current collector comprises a plurality of through holes penetrating through the negative electrode current collector along the thickness direction, and the through holes are arranged opposite to part of the alkali metal layer,

the surface roughness Ra of the negative electrode current collector satisfies the following conditions: ra is more than or equal to 0.2 mu m and less than or equal to 1 mu m;

the surface roughness Rz of the negative electrode current collector satisfies the following conditions: rz is less than or equal to 1.5 mu m and less than or equal to 4 mu m,

the percentage of area of the plurality of through holes is 40% to 70% based on the cross-sectional area of the negative electrode current collector parallel to a first direction, wherein the first direction is perpendicular to the thickness direction;

the alkali metal layer has an average thickness of 30 μm to 60 μm.

2. The negative electrode tab of claim 1, wherein the negative current collector comprises:

a first current collector disposed at one of the two sides, a portion of the plurality of through holes including a plurality of first through holes penetrating the first current collector in the thickness direction; and

the second current collector is arranged on the other side of the two sides, and the other part of the plurality of through holes comprise a plurality of second through holes penetrating through the second current collector along the thickness direction.

3. The negative electrode tab according to claim 2, wherein the first through holes and the second through holes are alternately arranged along a first direction, the first direction being perpendicular to the thickness direction; or (b)

The first through hole and the second through hole are oppositely arranged along the thickness direction.

4. The negative electrode tab according to claim 1, wherein the alkali metal layer includes a main body portion and a connecting portion connected to each other in the thickness direction, the negative electrode current collector is provided on the main body portion, and the connecting portion protrudes from the main body portion in the thickness direction and into the through hole.

5. The negative electrode tab of claim 4, wherein,

the edge of the negative electrode current collector in the thickness direction exceeds the edge of the connecting portion in the thickness direction.

6. The negative electrode tab of claim 1, wherein,

the plurality of through holes are uniformly distributed.

7. The negative electrode tab of claim 6, wherein the percentage of area of the plurality of through holes is 40% to 60% based on the cross-sectional area of the negative electrode current collector parallel to the first direction.

8. The negative electrode tab of claim 1, wherein,

the negative electrode current collector has an average thickness of 4 μm to 20 μm on one side.

9. The negative electrode tab of claim 1, wherein,

the negative electrode current collector includes a metal material.

10. The negative electrode tab of claim 1, wherein,

the alkali metal layer includes at least one of lithium metal and sodium metal.

11. A battery comprising the negative electrode tab of any one of claims 1 to 10.

12. An electrical device comprising the battery of claim 11.