CN116705981B

CN116705981B - Negative electrode plate, preparation method thereof, battery and electric equipment

Info

Publication number: CN116705981B
Application number: CN202310932838.3A
Authority: CN
Inventors: 泉贵岭; 马云建; 张伟鸿; 张加锡; 高杰; 姚萌; 唐代春; 杨瑞
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-07-27
Filing date: 2023-07-27
Publication date: 2024-05-03
Anticipated expiration: 2043-07-27
Also published as: CN116705981A

Abstract

The application discloses a negative electrode plate, a preparation method thereof, a battery and electric equipment, wherein the negative electrode plate comprises a current collector and a negative electrode active material layer, and at least one surface of the current collector comprises a first area and a second area; the negative electrode active material layer comprises a first negative electrode active material layer and a second negative electrode active material layer, the first negative electrode active material layer is arranged in the first region, and the second negative electrode active material layer is arranged in the second region; the second anode active material layer comprises a silicon-based material and an active metal ion supplementing layer, and the active metal ion supplementing layer is positioned on at least part of the surface of the silicon-based material. The secondary battery containing the negative electrode plate has excellent energy density and good initial effect and cycle performance.

Description

Negative electrode plate, preparation method thereof, battery and electric equipment

Technical Field

The application belongs to the technical field of secondary batteries, and particularly relates to a negative electrode plate, a preparation method thereof, a battery and electric equipment.

Background

The secondary battery is widely used not only in energy storage power supply systems such as hydraulic power, thermal power, wind power and solar power stations, but also in electric vehicles such as electric bicycles, electric motorcycles and electric automobiles, as well as in a plurality of fields such as military equipment and aerospace.

The silicon-based material is a negative electrode active material commonly used for secondary batteries. However, the existing secondary battery containing a silicon-based material has low initial coulombic efficiency and short cycle life.

Disclosure of Invention

In view of the technical problems in the background art, the application provides a negative electrode plate, and aims to solve the problems of low initial coulomb efficiency and short cycle life of a battery containing the negative electrode plate.

In order to achieve the above object, a first aspect of the present application provides a negative electrode tab, comprising: a current collector having at least one surface comprising a first region and a second region; the anode active material layer comprises a first anode active material layer and a second anode active material layer, wherein the first anode active material layer is arranged in the first area, and the second anode active material layer is arranged in the second area; the second anode active material layer comprises a silicon-based material and an active metal ion supplementing layer, and the active metal ion supplementing layer is positioned on at least part of the surface of the silicon-based material.

The application at least comprises the following beneficial effects: in the application, the second anode active material layer and the first anode active material layer containing the silicon-based material are distributed on the anode piece in a partitioned way, and in the second anode active material layer, the active metal ion supplementing layer is located on at least part of the surface of the silicon-based material in a targeted way, thereby improving the first coulombic efficiency and the cycle life of the secondary battery.

In some embodiments of the application, at least one surface of the current collector comprises a plurality of the first regions and a plurality of the second regions. Thereby, the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the first regions and the second regions are alternately arranged. Thereby, the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the first anode active material layer has a thickness of 100 μm to 250 μm. Thus, the thickness of the first anode active material layer is within the above range, and the first coulombic efficiency and the cycle life of the secondary battery can be improved.

In some embodiments of the application, the first anode active material layer has a thickness of 120 μm to 220 μm. Thus, the thickness of the first anode active material layer is within the above range, and the first coulombic efficiency and the cycle life of the secondary battery can be improved.

In some embodiments of the application, the first negative electrode active material layer includes at least one of a carbon-based material, a tin-based material, lithium titanate, or a metal capable of forming an alloy with lithium. Thus, the first negative electrode active material layer may improve the first coulombic efficiency and the cycle life of the secondary battery using at least one of the above substances.

In some embodiments of the application, the carbon-based material comprises at least one of artificial graphite, natural graphite, hard carbon, soft carbon, carbon fiber, or mesophase carbon microbeads. Thus, the first negative electrode active material layer may improve the first coulombic efficiency and the cycle life of the secondary battery using at least one of the above substances.

In some embodiments of the application, the silicon-based material forms a silicon layer, and the active metal ion supplement layer is located on at least part of the surface of the silicon layer. Therefore, the active metal ion supplementing layer is arranged on the surface of the silicon layer in a targeted manner, and is mainly used for supplementing active metal ions to the silicon layer, so that the first coulomb efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the silicon layer has a thickness of 2 μm to 60 μm. Thus, the secondary battery has excellent energy density within the thickness range of the silicon layer, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the silicon layer has a thickness of 45 μm to 55 μm. Thus, the secondary battery has excellent energy density within the thickness range of the silicon layer, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the silicon-based material comprises at least one of elemental silicon, a silicon oxygen compound, a silicon carbon composite, a silicon nitrogen composite, a silicon-containing alloy, or a silicon oxygen carbon composite. Thus, the silicon-based material adopts at least one of the above substances, and the secondary battery has excellent energy density, and can improve the first coulombic efficiency and the cycle storage life of the secondary battery.

In some embodiments of the application, the active metal ion supplement layer has a thickness of 1 μm to 30 μm. In the thickness range of the active metal ion supplementing layer, the loss of the active metal ions which are irreversible after the first charging of the silicon-based material can be just compensated, and the first coulomb efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the active metal ion supplement layer has a thickness of 5 μm to 25 μm. In the thickness range of the active metal ion supplementing layer, the loss of the active metal ions which are irreversible after the first charging of the silicon-based material can be just compensated, and the first coulomb efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the active metal ion supplemental layer comprises at least one of lithium, a lithium alloy, a lithium-containing oxide, a lithium-containing sulfide, a lithium-containing nitride, or a lithium-containing fluoride. Thus, the active metal ion supplementing layer adopts at least one of the substances, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the active metal ion supplemental layer comprises at least one of sodium, a sodium alloy, a sodium-containing oxide, a sodium-containing sulfide, a sodium-containing nitride, or a sodium-containing fluoride. Thus, the active metal ion supplementing layer adopts at least one of the substances, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the negative electrode tab further includes a conductive layer disposed between the current collector and the negative electrode active material layer. The conductive layer may enhance the conductive performance of the anode active material layer, and may enhance the first coulombic efficiency and the cycle storage life of the secondary battery.

In some embodiments of the application, the conductive layer is disposed between the current collector and the second anode active material layer. The conductive layer pertinently improves the conductivity of the second anode active material layer, and can improve the first coulombic efficiency and the cycle storage life of the secondary battery.

In some embodiments of the application, the conductive layer has a resistivity of 5 Ω -cm to 1000 Ω -cm. Thus, in the above-described range of resistivity of the conductive layer, the conductive performance of the second anode active material layer can be improved, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the conductive layer has a resistivity of 10Ω·cm to 300Ω·cm. Thus, in the above-described range of resistivity of the conductive layer, the conductive performance of the second anode active material layer can be improved, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the conductive layer has a thickness of 1 μm to 30 μm. Thus, in the thickness range of the above-mentioned conductive layer, the conductive performance of the second anode active material layer can be improved, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the conductive layer has a thickness of 2 μm to 15 μm. Thus, in the thickness range of the above-mentioned conductive layer, the conductive performance of the second anode active material layer can be improved, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the conductive layer comprises at least one of graphene, carbon nanotubes, carbon fibers, acetylene black, ketjen black, super P, copper powder, or silver powder. Thus, the conductive layer adopts at least one of the above substances, so that the conductivity of the second anode active material layer can be improved, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the second anode active material layer further comprises a protective layer disposed on a side of the active metal ion supplementing layer facing away from the current collector. Therefore, the protective layer can protect the active metal ion supplementing layer from oxidation and corrosion of electrolyte, and can improve the first coulombic efficiency and the cycle storage life of the secondary battery.

In some embodiments of the application, the protective layer has a conductivity of 0.2mS/cm to 10mS/cm. Therefore, the conductivity of the protective layer is in the range, the protective layer has excellent conductivity and active metal ion shuttle performance, and can play a role in protecting the active metal ion supplementing layer, so that the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the protective layer has a conductivity of 1mS/cm to 5mS/cm. Therefore, the conductivity of the protective layer is in the range, the protective layer has excellent conductivity and active metal ion shuttle performance, and can play a role in protecting the active metal ion supplementing layer, so that the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the protective layer has a porosity of 2% to 50%. Thus, the protective layer has excellent active metal ion shuttling property within the above range, and can improve the first coulombic efficiency and cycle storage life of the secondary battery.

In some embodiments of the application, the protective layer has a porosity of 15% to 35%. Thus, the protective layer has excellent active metal ion shuttling property within the above range, and can improve the first coulombic efficiency and cycle storage life of the secondary battery.

In some embodiments of the application, the protective layer has a thickness of 1 μm to 30 μm. Therefore, the thickness of the protective layer is in the range, the active metal ion supplementing layer can be protected from oxidation and corrosion of electrolyte, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the protective layer has a thickness of 1 μm to 15 μm. Therefore, the thickness of the protective layer is in the range, the active metal ion supplementing layer can be protected from oxidation and corrosion of electrolyte, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the protective layer comprises at least one of a first material comprising at least one of lithium sulfide, aluminum sulfide, phosphorus sulfide, silicon sulfide, titanium sulfide, or tin sulfide, polyethylene oxide, polypropylene oxide, polyvinylidene chloride, polyvinylidene fluoride, lithium lanthanum zirconium oxide, lanthanum lithium titanate, or a fast ion conductor. Therefore, the protective layer adopts at least one of the substances, has excellent conductivity and lithium ion shuttle performance, can protect the active metal ion supplementing layer from oxidation and corrosion of electrolyte, and can improve the first coulombic efficiency and the cycle storage life of the secondary battery.

In some embodiments of the present application, the second anode active material layer has a mass ratio of 1% to 25% based on the total mass of the anode active material layer. Thus, when the mass ratio of the second anode active material layer among the anode active material layers is within the above-described range, the first coulombic efficiency and the cycle life of the secondary battery can be improved.

In some embodiments of the present application, the mass ratio of the second anode active material layer is 3% to 15% based on the total mass of the anode active material layer. Thus, when the mass ratio of the second anode active material layer among the anode active material layers is within the above-described range, the first coulombic efficiency and the cycle life of the secondary battery can be improved.

In some embodiments of the application, the current collector has oppositely disposed first and second surfaces, each of which includes first and second regions, the first regions of the first surface and the first regions of the second surface being symmetrically disposed. Thereby, the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In a second aspect, the present application provides a method for preparing the negative electrode sheet according to the first aspect, including:

Forming a first anode active material layer at a first region of a current collector;

And forming a silicon-based material in a second region of the current collector, and forming an active metal ion supplementing layer on at least part of the surface of the silicon-based material.

Therefore, the negative electrode plate prepared by the application is provided with different negative electrode active materials in different areas, so that the secondary battery containing the negative electrode plate has excellent energy density and good initial effect and cycle performance.

In some embodiments of the present application, forming a silicon-based material in the second region of the current collector includes:

forming a conductive layer in the second region;

And forming a silicon-based material on one side of the conductive layer, which is away from the current collector.

In some embodiments of the application, further comprising: and forming a protective layer on one side of the active metal ion supplementing layer, which is away from the current collector.

A third aspect of the application provides a battery comprising a negative electrode sheet according to the first aspect of the application or a negative electrode sheet prepared by a method according to the second aspect. Thus, the battery has excellent initial coulombic efficiency and cycle life.

A fourth aspect of the application provides a powered device comprising a battery according to the third aspect.

Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:

fig. 1 is a schematic structural view of a negative electrode tab according to an embodiment of the present application;

FIG. 2 is a top view of FIG. 1;

Fig. 3 is a schematic structural view of a negative electrode tab according to another embodiment of the present application;

Fig. 4 is a schematic structural view of a negative electrode tab according to still another embodiment of the present application;

fig. 5 is a schematic view of the structure of a battery according to an embodiment of the present application;

Fig. 6 is a schematic view of the structure of a battery module according to an embodiment of the present application;

fig. 7 is a schematic view of a structure of a battery pack according to an embodiment of the present application;

FIG. 8 is an exploded view of FIG. 7;

Fig. 9 is a schematic diagram of an embodiment of a powered device with a battery as a power source.

Reference numerals illustrate:

1: a battery pack; 2: an upper case; 3: a lower box body; 4: a battery module; 5: a battery cell;

11: a negative electrode plate; 111: a current collector; 1111: a first region; 1112: a second region; 112: a negative electrode active material layer; 1121: a first anode active material layer; 1122: a second anode active material layer; 1122a: a silicon-based material; 1122b: an active metal ion supplementing layer; 1122c: a conductive layer; 1122d: and (3) a protective layer.

Detailed Description

Embodiments of the technical scheme of the present application are described in detail below. The following examples are only for more clearly illustrating the technical aspects of the present application, and thus are merely examples, and are not intended to limit the scope of the present application.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

For simplicity, only a few numerical ranges are specifically disclosed herein. However, any lower limit may be combined with any upper limit to form a range not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and any upper limit may be combined with any other upper limit to form a range not explicitly recited. Furthermore, each separately disclosed point or individual value may itself be combined as a lower limit or upper limit with any other point or individual value or with other lower limit or upper limit to form a range not explicitly recited.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having" and any variations thereof in the description of the application and the claims and the description of the drawings above are intended to cover a non-exclusive inclusion.

With the technological development and the improvement of demands of electric automobiles and chargeable mobile devices, secondary batteries are representative of the new energy field, and research work related thereto is also rapidly advancing. The secondary battery has small volume and weight, and is convenient to carry and use; the specific energy is higher, the larger energy storage capacity can be provided, and the lithium ion battery has no memory effect and does not need to be completely discharged and recharged, so that the secondary battery has wide application prospect.

In the current negative electrode plate of the secondary battery, the negative electrode active material is usually a graphite material, the specific capacity of the graphite material reaches the theoretical capacity upper limit (372 mAh/g), and the silicon-based material has the highest theoretical specific capacity (4200 mAh/g) which is more than 10 times of that of the graphite material, so that the graphite material is one of the negative electrode materials of the secondary battery with great application prospect.

However, the existing silicon-based materials have the following problems: on the one hand, when the lithium ion battery is charged, the volume expansion rate of the silicon-based material can reach 300% -400%, active metal ions (such as lithium ions) are separated out to form gaps when the lithium ion battery is discharged, strong stress can be generated due to obvious change of the volume, and silicon-based material particles are broken, so that the silicon-based material particles fall off from a negative electrode plate, the capacity is attenuated sharply, and the cycle life is reduced; on the other hand, the silicon-based material is pulverized due to the huge volume expansion of the silicon-based material, so that a large amount of active metal ions are lost along with the silicon-based material, so that serious irreversible active metal ion consumption is caused, and the first coulombic efficiency (first effect) is reduced.

In the application, the second anode active material layer and the first anode active material layer containing the silicon-based material are distributed on the anode piece in a partitioning way, and in the second anode active material layer, the active metal ion supplementing layer is located on at least part of the surface of the silicon-based material in a targeted way, on one hand, the irreversible active metal ion loss of primary charging is supplemented aiming at the silicon-based material with more lost active metal ions, the discharge capacity is improved, and the primary effect of the secondary battery is further improved; on the other hand, the active metal ion supplementing layer supplements active metal ions and leaves gaps, so that a space is reserved for the expansion of the silicon-based material, the fragmentation of silicon-based material particles caused by the expansion of the silicon-based material is reduced, and the cycle life of the secondary battery is prolonged.

The negative electrode plate disclosed by the embodiment of the application is suitable for a secondary battery, and the battery disclosed by the embodiment of the application can be used for electric equipment using the battery as a power supply or various energy storage systems using the battery as an energy storage element. The powered device may include, but is not limited to, a cell phone, tablet, notebook computer, electric toy, electric tool, battery car, electric car, ship, spacecraft, and the like. Among them, the electric toy may include fixed or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric plane toys, and the like, and the spacecraft may include planes, rockets, space planes, and spacecraft, and the like.

The first aspect of the present application proposes a negative electrode tab 11, referring to fig. 1 and 2, the negative electrode tab 11 includes a current collector 111 and a negative electrode active material layer 112, at least one surface of the current collector 111 includes a first region 1111 and a second region 1112; the anode active material layer 112 includes a first anode active material layer 1121 and a second anode active material layer 1122, the first anode active material layer 1121 is disposed in the first region 1111, and the second anode active material layer 1122 is disposed in the second region 1112; wherein the first negative electrode active material layer 1121 includes at least one of carbon and tin-based materials, the second negative electrode active material layer 1122 includes a silicon-based material 1122a and an active metal ion supplement layer 1122b, and the active metal ion supplement layer 1122b is located on at least a part of the surface of the silicon-based material 1122 a.

The application at least comprises the following beneficial effects: in the negative electrode plate, the second negative electrode active material layer and the first negative electrode active material layer which contain the silicon-based material are distributed on the negative electrode plate in a partition way, the silicon-based material improves the energy density of the secondary battery, and in the second negative electrode active material layer, the active metal ion supplementing layer is pertinently arranged on the surface of the silicon-based material, on one hand, the loss of active metal ions is supplemented for the silicon-based material with more active metal ions in the first charging loss, the discharge capacity is improved, and the first effect of the secondary battery is further improved; on the other hand, the active metal ion supplementing layer supplements active metal ions and leaves gaps, so that a space is reserved for the expansion of the silicon-based material, the fragmentation of silicon-based material particles caused by the expansion of the silicon-based material is reduced, and the cycle life of the secondary battery is prolonged. In conclusion, the secondary battery containing the negative electrode plate has excellent energy density and good initial effect and cycle performance.

In the secondary battery, conduction is achieved by transfer of active metal ions between the positive and negative electrodes: when the battery is charged, active metal ions in the positive electrode active material are separated, and the active metal ions move to the negative electrode through the electrolyte and are embedded; when the battery discharges, the active metal ions embedded in the negative electrode are separated and move back to the positive electrode. The active metal ions may include sodium ions and lithium ions. The active metal ion supplementing layer is used for supplementing active metal ions lost in the charge and discharge processes of the battery.

It is understood that the surface of the current collector means the surface of the current collector facing or facing away from the battery separator, and the sheet-shaped current collector has two surfaces disposed opposite to each other in the thickness direction thereof. The active metal ion supplementing layer is positioned on at least part of the surface of the silicon-based material, namely, the active metal ion supplementing layer is arranged on the surface of the silicon-based material and contacts with the silicon-based material to prevent the silicon-based material from contacting with other substances. The tin-based material means a material containing a tin element, and the silicon-based material means a material containing a silicon element.

It may be appreciated that, in the embodiment of the present application, the first anode active material layer and the second anode active material layer may be disposed on the current collector in a stacked manner, where at least a portion of the projection of the second area on the current collector coincides with the first area, and when the two layers are stacked, the first anode active material layer and the second anode active material layer may be disposed in sequence from a direction away from the current collector, or the second anode active material layer and the first anode active material layer may be disposed in sequence from a direction away from the current collector; the first anode active material layer and the second anode active material layer may be both directly provided on the surface of the current collector, and both are in direct contact with the surface of the current collector.

In some embodiments of the present application, when both the first anode active material layer and the second anode active material layer are directly provided on the surface of the current collector, the first anode active material layer and the second anode active material layer may be arranged in any manner, for example, one of the first anode active material layer and the second anode active material layer is provided, and both of them are arranged on the surface of the current collector in any manner (regular or irregular); for another example, the first anode active material layer and the second anode active material layer are each provided in plurality, and the plurality of first anode active material layers and the plurality of second anode active material layers may be arranged on the surface of the current collector in any manner (regular or irregular).

In some embodiments of the present application, referring to fig. 1, at least one surface of the current collector 111 includes a plurality of the first regions 1111 and a plurality of the second regions 1112. Thus, the first anode active material layer 1121 is disposed in the first region 1111 and the second anode active material layer 1122 is disposed in the second region 1112, which improves the uniformity of the distribution of the anode active material on the current collector, and can improve the first coulombic efficiency and the cycle storage life of the secondary battery.

In some embodiments of the present application, referring to fig. 1, the first regions and the second regions are alternately arranged. The plurality of first regions 1111 and the plurality of second regions 1112 are alternately arranged on the current collector, the first anode active material layer 1121 is disposed in the first region 1111, and the second anode active material layer 1122 is disposed in the second region 1112, so that the uniformity of the distribution of the anode active material on the current collector is improved, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the present application, the surface density of the first anode active material layer is 0.05g/1540.25mm ²-0.25g/1540.25mm², for example, the surface density of the first anode active material layer may be 0.05g/1540.25mm²-0.22g/1540.25mm²,0.08g/1540.25mm²-0.2g/1540.25mm²,0.1g/1540.25mm²-0.18g/1540.25mm²,0.12g/1540.25mm²-0.15g/1540.25mm², etc., and the surface density of the first anode active material layer is in the above range, on one hand, the porosity between anode active materials is high, the electrolyte between pores is more, active metal ions are easy to be transmitted, the membrane resistance and the charge transfer resistance are reduced, so that the battery polarization is reduced, the capacity loss is reduced during the cycle, and the cycle performance is improved; on the other hand, the side reaction on the surface of the negative electrode is reduced, the amount of active metal ions consumed by film formation in the primary charging process is reduced, and the primary coulomb efficiency is improved. In other embodiments of the present application, the first anode active material layer has an areal density of 0.12g/1540.25mm ²-0.19g/1540.25mm².

It is understood that the "areal density of the first anode active material layer" means the mass of the first anode active material layer per unit area on the surface of the current collector, and is a meaning well known in the art, and can be measured using instruments and methods well known in the art. For example, can be obtained by the following method:

The first step: the current collector is punched and cut into small discs with the area of 1540.25mm ², and the small discs are weighed, and the mass of the small discs is g1;

And a second step of: the pole piece after single-sided coating is punched into small discs with the area of 1540.25mm ², and the small discs are weighed, and the mass is g2;

areal density= (g 2-g 1)/1540.25, unit g/1540.25mm ².

Hereinafter, the surface density of the other layers is measured similarly to that of the first anode active material layer, and a detailed description thereof will be omitted.

In some embodiments of the present application, the thickness of the first anode active material layer is 100 μm to 250 μm, for example, the thickness of the first anode active material layer may be 100 μm to 245 μm,110 μm to 240 μm,130 μm to 230 μm,150 μm to 200 μm,170 μm to 180 μm, or the like. Specifically, the thickness of the first anode active material layer is within the above range, and the first coulombic efficiency and the cycle life of the secondary battery can be improved. In other embodiments of the present application, the first anode active material layer has a thickness of 120 μm to 220 μm.

In some embodiments of the application, the first negative electrode active material layer includes at least one of a carbon-based material, a tin-based material, lithium titanate, or other metal capable of forming an alloy with lithium. The first negative electrode active material layer adopts at least one of the substances, so that the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

It is understood that a metal capable of forming an alloy with lithium refers to an alloy of metallic lithium with other metallic elements or non-metallic elements. Other metal elements include tin (Sn), zinc (Zn), aluminum (Al), magnesium (Mg), silver (Ag), gold (Au), gallium (Ga), indium (In), platinum (Pt), and the like. The nonmetallic elements include boron (B), carbon (C), silicon (Si), and the like.

In some embodiments of the application, the carbon-based material comprises at least one of artificial graphite, natural graphite, composite graphite, hard carbon, soft carbon, carbon fiber, or mesophase carbon microsphere. Thus, the first negative electrode active material layer may improve the first coulombic efficiency and the cycle life of the secondary battery using at least one of the above substances.

In some embodiments of the application, the silicon-based material forms a silicon layer, and the active metal ion supplement layer is located on at least part of the surface of the silicon layer. Specifically, the active metal ion supplementing layer being located on at least part of the surface of the silicon layer means that the active metal ion supplementing layer is located on at least part of the surface of the silicon layer, and the silicon layer is blocked from being contacted with other substances. The active metal ion supplementing layer is purposefully arranged on the surface of the silicon layer, and is mainly used for supplementing active metal ions to the silicon layer, so that the first coulomb efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the present application, the surface density of the silicon layer is 0.05g/1540.25mm ²-0.15g/1540.25mm², for example, the surface density of the silicon layer may be 0.05g/1540.25mm²-0.14g/1540.25mm²,0.06g/1540.25mm²-0.13g/1540.25mm²,0.07g/1540.25mm²-0.12g/1540.25mm²,0.08g/1540.25mm²-0.11g/1540.25mm²,0.09g/1540.25mm²-0.1g/1540.25mm², where on one hand, the porosity between the anode active materials is high, the electrolyte between the pores is more, the active metal ions are easy to be transported, the membrane resistance and the charge transfer resistance are reduced, so that the battery polarization is reduced, the capacity loss is reduced during the cycling process, and the cycling performance is improved; on the other hand, the negative electrode surface side reaction decreases, the amount of active metal ions consumed for film formation during the first charge decreases, the first coulombic efficiency increases, and furthermore, the secondary battery has excellent energy density. In other embodiments of the application, the areal density of the silicon layer is 0.07g/1540.25mm ²-0.12g/1540.25mm².

In some embodiments of the present application, the silicon layer has a thickness of 2 μm to 60 μm, for example, the silicon layer may have a thickness of 2 μm to 55 μm,5 μm to 50 μm,10 μm to 45 μm,15 μm to 40 μm,20 μm to 35 μm,25 μm to 30 μm, etc., and the secondary battery has an excellent energy density within the thickness range of the silicon layer, which may improve the first coulombic efficiency and the cycle storage life of the secondary battery. In other embodiments of the application, the silicon layer has a thickness of 45 μm to 55 μm.

In some embodiments of the present application, the surface density of the active metal ion supplementing layer is 0.08mg/1540.25mm ²-0.15mg/1540.25mm², for example, the surface density of the active metal ion supplementing layer may be 0.08mg/1540.25mm²-0.14mg/1540.25mm²,0.09mg/1540.25mm²-0.13mg/1540.25mm²,0.1mg/1540.25mm²-0.12mg/1540.25mm², etc., and in the above range, the surface density of the active metal ion supplementing layer just can compensate the loss of the active metal ion which is irreversible when the silicon-based material is charged for the first time, so that the first coulombic efficiency and the cycle storage life of the secondary battery can be improved. In other embodiments of the application, the areal density of the active metal ion supplement layer is 0.08mg/1540.25mm ²-0.1mg/1540.25mm².

In some embodiments of the application, the active metal ion supplement layer has a thickness of 1 μm to 30 μm, for example, the active metal ion supplement layer may have a thickness of 1 μm to 28 μm,5 μm to 25 μm,10 μm to 20 μm,15 μm to 20 μm, etc. In the thickness range of the active metal ion supplementing layer, the loss of the active metal ions which are irreversible after the first charging of the silicon-based material can be just compensated, and the first coulomb efficiency and the cycle storage life of the secondary battery can be improved. In other embodiments of the application, the thickness of the active metal ion supplement layer is from 5 μm to 25 μm.

In some embodiments of the application, the active metal ion supplemental layer comprises at least one of lithium, a lithium alloy, a lithium-containing oxide, a lithium-containing sulfide, a lithium-containing nitride, or a lithium-containing fluoride. Therefore, the secondary battery comprises a lithium ion battery, and the active metal ion supplementing layer adopts at least one of the substances, so that the irreversible lithium loss caused by the first charging of the silicon-based material can be supplemented, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the active metal ion supplemental layer comprises at least one of sodium, a sodium alloy, a sodium-containing oxide, a sodium-containing sulfide, a sodium-containing nitride, or a sodium-containing fluoride. Therefore, the secondary battery comprises a sodium ion battery, and the active metal ion supplementing layer adopts at least one of the substances, so that irreversible sodium loss caused by the first charge of the silicon-based material can be supplemented, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the present application, the negative electrode tab further includes a conductive layer disposed between the current collector and the negative electrode active material layer, and the conductive layer may enhance the overall conductivity of the second negative electrode active material layer, enhancing the first coulombic efficiency and the cycle storage life of the secondary battery.

In some embodiments of the present application, referring to fig. 3, the conductive layer 1122c is disposed between the current collector 111 and the second negative electrode active material layer 1122, and in particular, the conductive layer 1122c is disposed between the current collector 111 and the silicon-based material 1122 a. Specifically, the conductive layer 1122c, on the one hand, serves as an electron conduction bridge between the current collector 111 and the silicon-based material 1122a, and may enhance the conductivity of the second negative electrode active material layer 1122; on the other hand, the silicon-based material 1122a and the current collector 111 can be isolated, damage to the current collector 111 caused by direct contact of the silicon-based material 1122a and the current collector 111 is reduced, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the application, the areal density of the conductive layer is 0.05g/1540.25mm ²-0.25g/1540.25mm², for example, the areal density of the conductive layer may be 0.05g/1540.25mm²-0.22g/1540.25mm²,0.08g/1540.25mm²-0.2g/1540.25mm²,0.1g/1540.25mm²-0.18g/1540.25mm²,0.12g/1540.25mm²-0.15g/1540.25mm², or the like. Therefore, in the area density range of the conductive layer, the conductive performance of the second anode active material layer can be improved, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved. In other embodiments of the application, the areal density of the conductive layer is 0.05g/1540.25mm ²-0.15g/1540.25mm².

In some embodiments of the present application, the conductive layer may have a resistivity of 5 Ω·cm to 1000 Ω·cm, for example, the conductive layer may have a resistivity of 5 Ω·cm to 900 Ω·cm,50 Ω·cm to 800 Ω·cm,100 Ω·cm to 700 Ω·cm,200 Ω·cm to 600 Ω·cm,300 Ω·cm to 500 Ω·cm, and the like, and in particular, the conductive layer may have a resistivity within a range that may improve the conductivity of the second anode active material layer and may improve the first coulombic efficiency and the cycle life of the secondary battery. In other embodiments of the present application, the resistivity of the conductive layer is from 10Ω·cm to 300Ω·cm.

It will be appreciated that "resistivity" is a meaning well known in the art and can be measured using instruments and methods well known in the art. For example, can be obtained by the following method:

Four wires are used, two for measuring the current of the conductor to be measured and the other two for measuring the voltage on the conductor. By measuring the ratio of the current and the voltage, the resistance value can be calculated. Then, the resistivity is calculated from the length and the sectional area of the conductor.

In some embodiments of the application, the conductive layer has a thickness of 1 μm to 30 μm, for example, the conductive layer may have a thickness of 1 μm to 28 μm,5 μm to 25 μm,10 μm to 20 μm,15 μm to 18 μm, etc. Specifically, in the thickness range of the above-mentioned conductive layer, the conductive performance of the second anode active material layer can be improved, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved. In other embodiments of the application, the conductive layer has a thickness of 2 μm to 15 μm.

In some embodiments of the present application, the conductive layer includes at least one of graphene, carbon nanotubes, carbon fibers, acetylene black, ketjen black, super P (conductive carbon black), copper powder, or silver powder. Thus, the conductive layer adopts at least one of the above substances, so that the conductivity of the second anode active material layer can be improved, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

In some embodiments of the present application, referring to fig. 4, the second anode active material layer 1122 further includes a protective layer 1122d disposed on a side of the active metal ion supplementing layer 1122b facing away from the current collector 111. Thus, the protective layer 1122d may protect the active metal ion replenishment layer 1122b from oxidation and corrosion by the electrolyte, and may improve the first coulombic efficiency and the cycle life of the secondary battery.

In some embodiments of the present application, the electrical conductivity of the protective layer is 0.2mS/cm to 10mS/cm, for example, the electrical conductivity of the protective layer may be 0.2mS/cm to 9mS/cm,1mS/cm to 8mS/cm,2mS/cm to 7mS/cm,3mS/cm to 6mS/cm,4mS/cm to 5mS/cm, etc., and thus, the electrical conductivity of the protective layer is in the above range, has excellent electrical conductivity and active metal ion shuttle property, improves the energy density of the battery, and can function to protect the active metal ion supplemental layer, and can improve the first coulombic efficiency and the cycle storage life of the secondary battery. In other embodiments of the application, the protective layer has a conductivity of 1mS/cm to 5mS/cm.

It will be understood that "conductivity" is a meaning well known in the art and can be measured using instrumentation and methods well known in the art. For example, can be obtained by the following method:

Double blocking current dc polarization method:

The first step: manufacturing the protective layer into a test piece with the thickness of 10mm and the area of 1540.25mm ²;

And a second step of: assembling the test piece into a pair of batteries;

and a third step of: and adding blocking batteries at two sides of the symmetrical battery to perform impedance test, thereby obtaining conductivity.

In some embodiments of the present application, the porosity of the protective layer is 2% -50%, for example, the porosity of the protective layer may be 2% -45%,10% -40%,20% -30%, etc., and thus, the porosity of the protective layer is in the above range, has excellent active metal ion shuttling properties, and can function as a protective active metal ion supplementing layer, and can improve the first coulombic efficiency and the cycle storage life of the secondary battery. In other embodiments of the application, the protective layer has a porosity of 15% to 35%.

It will be appreciated that "porosity" is a meaning well known in the art and can be measured using instruments and methods well known in the art. For example, can be obtained by the following method:

The first step: taking part of the protective layer film finished product material, measuring the length, width and thickness of the protective layer film finished product material, and calculating the volume V;

And a second step of: weighing the protection layer with the mass of M;

and a third step of: calculate porosity = (material density x V-M)/(material density x V)

In some embodiments of the present application, the thickness of the protective layer may be 1 μm to 30 μm, for example, the thickness of the protective layer may be 1 μm to 28 μm,5 μm to 25 μm,10 μm to 20 μm,15 μm to 20 μm, etc., whereby the thickness of the protective layer is within the above-described range, the active metal ion supplementing layer may be protected from oxidation and corrosion by the electrolyte, and the first coulombic efficiency and the cycle storage life of the secondary battery may be improved. In other embodiments of the application, the protective layer has a thickness of 1 μm to 15 μm.

In some embodiments of the application, the protective layer comprises at least one of a first material comprising at least one of lithium sulfide, aluminum sulfide, phosphorus sulfide, silicon sulfide, titanium sulfide, or tin sulfide, polyethylene oxide, polypropylene oxide, polyvinylidene chloride, polyvinylidene fluoride, lithium lanthanum zirconium oxide, lanthanum lithium titanate, or a fast ion conductor. Therefore, the material belongs to solid electrolyte, the protective layer adopts at least one of the materials, has excellent conductivity and lithium ion shuttle performance, can protect the active metal ion supplementing layer from oxidation and corrosion of electrolyte, and can improve the first coulombic efficiency and the cycle storage life of the secondary battery.

In some embodiments of the present application, the mass ratio of the second anode active material layer is 1% -25% based on the total mass of the anode active material layer, for example, the mass ratio of the second anode active material layer may be 1% -22%,5% -20%,10% -18%,12% -15% based on the total mass of the anode active material layer, and the like. Thus, when the mass ratio of the second anode active material layer among the anode active material layers is within the above-described range, the secondary battery is high in first coulombic efficiency and cycle life, and high in energy density. In other embodiments of the present application, the second anode active material layer has a mass ratio of 3% to 15% based on the total mass in the anode active material layer.

It can be understood that, when the second anode active material layer does not include the conductive layer and the protective layer, in the anode active material layer, the mass ratio of the second anode active material layer= (mass of silicon-based material+mass of active metal ion supplement layer)/total mass of the anode active material layer; when the second anode active material layer includes the conductive layer and/or the protective layer, in the anode active material layer, the mass ratio of the second anode active material layer= (mass of silicon-based material+mass of active metal ion supplement layer+mass of conductive layer and/or mass of protective layer)/total mass of the anode active material layer.

In some embodiments of the application, the current collector has oppositely disposed first and second surfaces, each of which includes first and second regions, the first regions of the first surface and the first regions of the second surface being symmetrically disposed. Thus, smooth transfer of active metal ions can be promoted, and the first coulombic efficiency and the cycle storage life of the secondary battery can be improved.

It is understood that the first region of the first surface and the first region of the second surface are symmetrically disposed means that the first region of the first surface and the first region of the second surface are axisymmetric with respect to a plane in which the current collector is located.

In some embodiments of the present application, the current collector comprises at least one of copper foil, polyethylene terephthalate/copper composite metal foil, polyethylene terephthalate/aluminum composite metal foil, titanium foil and silver foil, and the current collector has good conductivity and flexibility and strong stability.

In some embodiments of the application, the current collector has a thickness of 3 μm to 25 μm, for example, the current collector may have a thickness of 3 μm to 24 μm,5 μm to 20 μm,10 μm to 20 μm,15 μm to 20 μm, etc.

S100: forming a first negative electrode active material layer on a first region of a current collector

The current collectors are arranged in a partitioned mode, and different negative electrode active materials are arranged in different areas, so that the secondary battery containing the negative electrode plate has excellent energy density and good first effect and cycle performance.

S200: forming a silicon-based material in a second region of the current collector, and forming an active metal ion supplementing layer on at least part of the surface of the silicon-based material

In some embodiments of the present application, forming the silicon-based material in the second region of the current collector includes:

S201: forming a conductive layer in the second region

S202: forming a silicon-based material on one side of the conductive layer facing away from the current collector

On one hand, the conductive layer is used as an electron conduction bridge of the current collector and the silicon-based material, so that the conductive performance of the second anode active material layer can be improved; on the other hand, the silicon-based material and the current collector can be isolated, the damage to the current collector caused by the direct contact of the silicon-based material and the current collector is reduced, and the first coulomb efficiency and the cycle storage life of the secondary battery can be improved.

The protective layer can protect the active metal ion supplementing layer from oxidation and corrosion of electrolyte, and can improve the first coulombic efficiency and the cycle storage life of the secondary battery.

The second negative electrode active material layer and the first negative electrode active material layer which contain the silicon-based material are distributed on the negative electrode plate in a partitioned manner, and in the second negative electrode active material layer, the active metal ion supplementing layer is pertinently positioned on at least part of the surface of the silicon-based material, so that on one hand, irreversible active metal ion loss caused by primary charging is supplemented for the silicon-based material, and the primary coulombic efficiency of the secondary battery is improved; on the other hand, after the active metal ion supplementing layer supplements active metal ions, a space is reserved for the expansion of the silicon-based material, so that the fragmentation of silicon-based material particles caused by the expansion of the silicon-based material is reduced, and the cycle life of the secondary battery is prolonged.

In some embodiments of the present application, the first anode active material layer and the silicon-based material may be formed by coating, and the active metal ion supplementing layer may be formed by rolling an active metal foil.

In some embodiments of the present application, if the second negative electrode active material layer further includes a conductive layer and/or a protective layer, the conductive layer and/or the protective layer are formed by coating.

The negative electrode active material layer typically also optionally includes a binder, a conductive agent, and other optional adjuvants.

As an example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

As an example, the binder may include one or more of styrene-butadiene rubber (SBR), aqueous acrylic resin (water-based ACRYLIC RESIN), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

Other optional adjuvants may include thickening and dispersing agents (e.g., sodium carboxymethyl cellulose CMC-Na), PTC thermistor materials, as examples.

The battery is a battery that can be continuously used by activating an active material by means of charging after discharging.

It can be understood that the battery provided by the application can be a lithium ion battery, and at the moment, the active metal ions are lithium ions, and the active metal ion supplementing layer is a lithium supplementing layer; the active metal ion is sodium ion, and the active metal ion supplementing layer is sodium supplementing layer.

Typically, a battery includes a positive electrode tab, a negative electrode tab, a separator, and an electrolyte. During the charge and discharge of the battery, active metal ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece to play a role in isolation. The electrolyte plays a role in conducting active metal ions between the positive electrode plate and the negative electrode plate.

[ Positive electrode sheet ]

In some embodiments of the application, the positive electrode sheet comprises a positive electrode current collector, which may be a metal foil, a foam metal, or a composite current collector. For example, as the metal foil, silver-surface-treated aluminum or stainless steel, copper, aluminum, carbon electrode, carbon, nickel, titanium, or the like can be used. The composite current collector may include a polymeric material base layer and a metal layer. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, foam carbon or the like. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (e.g., a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

In some embodiments of the present application, the positive electrode sheet may further include a positive electrode active material layer including a positive electrode active material, and the specific kind of the positive electrode active material is not limited, and active materials known in the art to be used for a positive electrode of a battery may be used, and may be selected according to actual needs by those skilled in the art.

When the battery is a lithium ion battery, the positive electrode active material may include, but is not limited to, at least one of lithium transition metal oxide, olivine-structured lithium-containing phosphate, and their respective modified compounds, as examples. 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 modified compounds thereof. Examples of the olivine structured lithium-containing phosphate 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 modified compounds thereof. These materials are commercially available.

When the battery is a sodium ion battery, the positive electrode active material may include, but is not limited to, at least one of a layered transition metal oxide, a polyanion compound, and a prussian blue analog, as examples.

Examples of the layered transition metal oxide include:

na _1-xCu_hFe_kMn_lM¹ _mO_2-y, wherein M ¹ is at least one of Li, be, B, mg, al, K, ca, ti, co, ni, zn, ga, sr, Y, nb, mo, in, sn and Ba, 0< x is less than or equal to 0.33,0< h is less than or equal to 0.24,0, k is less than or equal to 0.32,0< 0.68,0 is less than or equal to M <0.1, h+k+l+m=1, and 0< y <0.2;

na _0.67Mn_0.7Ni_zM² _0.3-zO₂, wherein M ² is at least one of Li, mg, al, ca, ti, fe, cu, zn and Ba, and 0<z is less than or equal to 0.1;

na _aLi_bNi_cMn_dFe_eO₂, wherein 0.67< a.ltoreq.1, 0< b <0.2,0< c <0.3,0.67< d+e <0.8, b+c+d+e=1.

Examples of the polyanion compound include:

A ¹ _fM³ _g(PO₄)_iO_jX¹ _3-j, wherein A ¹ is at least one of H, li, na, K and NH ₄, M ³ is at least one of Ti, cr, mn, fe, co, ni, V, cu and Zn, X ¹ is at least one of F, cl and Br, 0<f is less than or equal to 4,0 is less than or equal to 2,1 is less than or equal to i is less than or equal to 3, and 0 is less than or equal to j is less than or equal to 2;

Na _nM⁴PO₄X², wherein M ⁴ is at least one of Mn, fe, co, ni, cu and Zn, X ² is at least one of F, cl and Br, 0<n is less than or equal to 2;

na _pM⁵ _q(SO₄)₃, wherein M ⁵ is at least one of Mn, fe, co, ni, cu and Zn, 0<p is less than or equal to 2, and 0< q is less than or equal to 2;

Na _sMn_tFe_3-t(PO₄)₂(P₂O₇), wherein 0<s.ltoreq.4, 0.ltoreq.t.ltoreq.3, e.g.t is 0,1, 1.5, 2 or 3.

As examples of the above prussian blue analogues, for example, there may be mentioned:

A _uM⁶ _v[M⁷(CN)₆]_w·xH₂ O, wherein A is at least one of H ⁺、NH₄ ⁺, alkali metal cations and alkaline earth metal cations, M ⁶ and M ⁷ are each independently at least one of transition metal cations, 0<u.ltoreq.2, 0< v.ltoreq.1, 0< w.ltoreq.1, 0< x.ltoreq.6. For example, a is at least one of H⁺、Li⁺、Na⁺、K⁺、NH₄ ⁺、Rb⁺、Cs⁺、Fr⁺、Be²⁺、Mg²⁺、Ca²⁺、Sr²⁺、Ba²⁺ and Ra ²⁺, and M ⁶ and M ⁷ are each independently a cation of at least one transition metal element of Ti, V, cr, mn, fe, co, ni, cu, zn, sn and W.

The battery is charged and discharged with the deintercalation and consumption of Li or Na, and the molar content of Li or Na is different when the battery is discharged to different states. In the list of the positive electrode materials in the embodiment of the application, the molar content of Li or Na is the initial state of the materials, namely the state before feeding, and the molar content of Li or Na can be changed after charge and discharge cycles when the positive electrode materials are applied to a battery system.

In the examples of the positive electrode material according to the present application, the molar content of O is only a theoretical state value, the molar content of oxygen may be changed due to lattice oxygen release, and the molar content of actual O may float.

The modifying compound of each material can be doping modification and/or surface coating modification of the material.

The positive electrode active material layer typically also optionally includes a binder, a conductive agent, and other optional adjuvants.

As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, super P (SP), graphene, and carbon nanofibers.

As an example, the adhesive may include at least one of styrene-butadiene rubber (SBR), aqueous acrylic resin (water-based ACRYLIC RESIN), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[ Electrolyte ]

The electrolyte may include an electrolyte salt and a solvent.

As an example, when the battery is a lithium ion battery, the electrolyte lithium salt may include at least one of lithium hexafluorophosphate (LiPF ₆), lithium tetrafluoroborate (LiBF ₄), lithium perchlorate (LiClO ₄), lithium hexafluoroarsenate (LiAsF ₆), lithium bis-fluorosulfonyl imide (LiFSI), lithium bis-trifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalato borate (lipfob), lithium dioxaato borate (LiBOB), lithium difluorophosphate (LiPO ₂F₂), lithium difluorodioxaato phosphate (LiDFOP), and lithium tetrafluorooxalato phosphate (LiTFOP).

As an example, when the battery is a sodium ion battery, the electrolyte sodium salt includes at least one of sodium hexafluorophosphate, sodium difluorooxalato borate, sodium tetrafluoroborate, sodium bisoxalato borate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis (fluorosulfonyl) imide, sodium trifluoromethylsulfonate, and sodium bis (trifluoromethylsulfonyl) imide.

As an example, the solvent may include 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 of the application, additives are 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 performance of the battery.

[ Isolation Membrane ]

The separator is not particularly limited, and any known porous separator having electrochemical stability and mechanical stability may be used according to actual needs, and may include, for example, a single-layer or multi-layer film comprising at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

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

In some embodiments, the battery cell may include an outer package. The outer package is used for packaging the positive electrode plate, the negative electrode plate and the electrolyte.

In some embodiments, the outer package may include a housing and a cover. Wherein, the casing can include the bottom plate and connect the curb plate on the bottom plate, and bottom plate and curb plate enclose and close and form the chamber that holds. The shell is provided with an opening communicated with the accommodating cavity, and the cover plate can be covered on the opening to seal the accommodating cavity.

The positive electrode sheet, the negative electrode sheet and the separator may be formed into an electrode assembly through a winding process or a lamination process. The electrode assembly is encapsulated in the accommodating cavity. The number of electrode assemblies included in the battery cell may include one or more and may be adjusted according to the need.

In some embodiments, the exterior packaging of the battery cell may include a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell.

The outer package of the battery cell may also include a pouch, such as a pouch-type pouch. The soft bag may be made of plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

In some embodiments, the battery cells may be assembled into a battery module, and the number of the batteries contained 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. 6 is a battery module 4 as an example. Referring to fig. 6, in the battery module 4, a plurality of battery cells 5 may be sequentially arranged in 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.

The battery module 4 may further include a case 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. 7 and 8 are battery packs 1 as an example. Referring to fig. 7 and 8, a battery case and a plurality of battery modules 4 disposed in the battery case 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 can be covered on 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.

A fifth aspect of the application provides a powered device comprising a battery as described in the fourth aspect. Specifically, the battery can be used as a power supply of the electric equipment and also can be used as an energy storage unit of the electric equipment. The powered device may include, but is not limited to, mobile devices (e.g., cell phones, notebook computers), electric vehicles (e.g., electric only vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, watercraft and satellites, energy storage systems.

Fig. 9 is a powered device as an example. The electric equipment comprises a pure electric vehicle, a hybrid electric vehicle or a plug-in hybrid electric vehicle.

As another example, the powered device may include a cellular phone, a tablet computer, a notebook computer. The electric equipment is required to be light and thin, and a battery can be used as a power supply.

In order to make the technical problems, technical schemes and beneficial effects solved by the embodiments of the present application more clear, the following will be described in further detail with reference to the embodiments and the accompanying drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses. All other embodiments, which can be made by a person skilled in the art based on the embodiments of the application without any inventive effort, are intended to fall within the scope of the application.

Example 1

[ Preparation of Positive electrode sheet ]

Weighing polyvinylidene fluoride (PVDF) with the mass percentage of 2%, 2% conductive agent super P and 96% lithium cobaltate (LiCoO ₂), sequentially adding the materials into N-methylpyrrolidone (NMP), and fully stirring and uniformly mixing the materials to prepare the positive electrode slurry. The slurry was coated into an aluminum foil 9 μm thick to be dried, and then rolled to prepare a positive electrode.

[ Preparation of negative electrode sheet ]

According to the anode sheet structure of fig. 1, a graphite layer (a first anode active material layer) and a second anode active material layer are transversely arranged side by side, wherein the left side, the right side and the upper layer of the second anode active material layer are covered by lithium metal, the thickness of the graphite layer is 40 μm, the graphite layer is made of 97% graphite, 1.5% conductive carbon black (SP) and 1.5% polyacrylic acid (PAA), the second anode active material layer is made of 90% carbon-coated silicon oxide (SiO _x, 0.7 < x < 1.5) (silicon-oxygen-carbon composite material), 3% conductive carbon black (SP) and 7% polyacrylic acid (PAA), the thickness is 30 μm, the upper lithium metal is made of metal lithium foil, the thickness of the lower conductive layer is made of Super P, the thickness of the upper lithium metal layer is 5 μm, and the left lithium layer and the right lithium layer are made of metal lithium foil to have a thickness of 3 μm. The specific conductive layer and the graphite layer are realized by adopting a gap coating mode, and the lithium layer is realized by adopting a spacing lithium foil rolling mode.

[ Electrolyte preparation ]

By dissolving 1M LiPF ₆ in the addition of vinylene carbonate to ethylene carbonate, diethyl carbonate and dimethyl carbonate to 1:1:2 in a solvent mixed in a volume ratio to prepare an electrolyte solution.

After the positive electrode and the negative electrode prepared using the polyethylene separator were prepared into a battery by a conventional method, the prepared electrolyte solution was injected to prepare a secondary battery.

The secondary batteries including the negative electrode tabs of examples 2 to 41 and comparative examples 1 to 3 were the same as example 1 except for the parameters (see table 1), wherein in comparative example 3, the first negative electrode active material layer was a graphite and silicon oxygen carbon composite material (SiO _x, 0.7 < x < 1.5) in a mass ratio of 1:1.

Parameters of the negative electrode sheets of examples 1 to 41 and comparative examples 1 to 3 of the present application are shown in Table 1.

TABLE 1

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In table 1, "/" indicates no addition.

Performance test:

1. Energy density testing:

Volumetric energy density = capacity x voltage plateau/cell volume

Taking example 1 as an example, a secondary battery was charged to 4.5V at 0.5C at 25 ℃, and then discharged to 2.5V at 0.5C, and the discharge capacity of the battery was the capacity of the battery;

the voltage platform is 3.91V;

cell volume = cell length х cell width х cell thickness.

The length and width tests were performed using a Charge Coupled Device (CCD) and the thickness test was performed using a Panel Pressure Gap (PPG) gauge.

2. And (3) battery initial efficiency test:

taking example 1 as an example, a secondary battery was charged to 4.5V at 0.5C and then discharged to 2.5V at 0.5C at 25C, resulting in a first discharge capacity of the battery and a first charge capacity of the battery, battery first efficiency=first discharge capacity of the battery/first charge capacity of the battery.

3. Battery cycle life test:

Taking example 1 as an example, the secondary battery of example 1 was charged to a charge end voltage of 4.5V at 1C, then discharged to a discharge end voltage of 2.5V at 1C, and the cyclic capacity retention rate reached 80% discharge capacity retention rate, the number of cycles was recorded, and the discharge capacity retention rate = battery post-cycle capacity/battery initial capacity, and the results are shown in table 2.

TABLE 2

As can be seen from table 2, in examples 1 to 41 of the present application, the second anode active material layer and the first anode active material layer containing the silicon-based material were distributed on the anode tab in a partitioned manner, and the secondary battery had excellent energy density and good initial efficiency and cycle performance. In comparison with examples 1 to 41, the negative electrode active material layer of comparative example 2 was graphite, and the negative electrode active material layer of comparative example 3 was uniformly mixed with a silicon-based material without the active metal ion supplement layer, and the energy density, first-order effect and cycle performance were inferior to those of examples 1 to 41.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application, and are intended to be included within the scope of the appended claims and description. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims

1. A negative electrode tab, comprising:

a current collector, at least one surface of which includes first and second regions alternately arranged;

The anode active material layer comprises a first anode active material layer and a second anode active material layer, wherein the first anode active material layer is arranged in the first area, and the second anode active material layer is arranged in the second area;

The second anode active material layer comprises a silicon-based material and an active metal ion supplementing layer, the active metal ion supplementing layer is positioned on at least part of the surface of the silicon-based material and wraps the silicon-based material, a gap is left after active metal ions are supplemented by the active metal ion supplementing layer, and the first anode active material layer comprises at least one of a carbon-based material, a tin-based material, lithium titanate or a metal capable of forming an alloy with lithium;

the negative electrode tab further includes a conductive layer disposed between the current collector and the negative electrode active material layer.

2. The negative electrode tab of claim 1, wherein at least one surface of the current collector comprises a plurality of the first regions and a plurality of the second regions.

3. The negative electrode tab according to claim 1 or 2, wherein the thickness of the first negative electrode active material layer is 100 μm to 250 μm.

4. The negative electrode tab according to claim 1 or 2, wherein the thickness of the first negative electrode active material layer is 120 μm to 220 μm.

5. The negative electrode tab of claim 1, wherein the carbon-based material comprises at least one of artificial graphite, natural graphite, hard carbon, soft carbon, carbon fiber, or mesophase carbon microspheres.

6. The negative electrode tab of claim 1 or 2, wherein the silicon-based material forms a silicon layer, and the active metal ion supplement layer is located on at least a portion of a surface of the silicon layer.

7. The negative electrode tab of claim 6, wherein the silicon layer has a thickness of 2-60 μm.

8. The negative electrode tab of claim 6, wherein the silicon layer has a thickness of 45-55 μm.

9. The negative electrode tab of claim 1 or 2, wherein the silicon-based material comprises at least one of elemental silicon, a silicon oxygen compound, a silicon carbon compound, a silicon nitrogen compound, a silicon-containing alloy, or a silicon oxygen carbon composite.

10. The negative electrode tab according to claim 1 or 2, wherein the thickness of the active metal ion supplementing layer is 1 μm-30 μm.

11. The negative electrode tab according to claim 1 or 2, wherein the thickness of the active metal ion supplementing layer is 5-25 μm.

12. The negative electrode tab of claim 1 or 2, wherein the active metal ion supplemental layer comprises at least one of lithium, a lithium alloy, a lithium-containing oxide, a lithium-containing sulfide, a lithium-containing nitride, or a lithium-containing fluoride; or alternatively

The active metal ion supplemental layer includes at least one of sodium, a sodium alloy, a sodium-containing oxide, a sodium-containing sulfide, a sodium-containing nitride, or a sodium-containing fluoride.

13. The negative electrode tab of claim 1, wherein the conductive layer is disposed between the current collector and the second negative electrode active material layer.

14. The negative electrode tab of claim 1, wherein the conductive layer has a resistivity of 5 Ω -cm to 1000 Ω -cm.

15. The negative electrode tab of claim 1, wherein the conductive layer has a resistivity of 10 Ω -cm to 300 Ω -cm.

16. The negative electrode tab of claim 1, wherein the conductive layer has a thickness of 1 μm to 30 μm.

17. The negative electrode tab of claim 1, wherein the conductive layer has a thickness of 2 μιη -15 μιη.

18. The negative electrode tab of claim 1, wherein the conductive layer comprises at least one of graphene, carbon nanotubes, carbon fibers, acetylene black, ketjen black, super P, copper powder, or silver powder.

19. The negative electrode tab according to claim 1 or 2, wherein the second negative electrode active material layer further comprises a protective layer provided on a side of the active metal ion supplementing layer facing away from the current collector.

20. The negative electrode tab of claim 19, wherein the protective layer has a conductivity of 0.2mS/cm to 10mS/cm.

21. The negative electrode tab of claim 19, wherein the protective layer has a conductivity of 1mS/cm to 5mS/cm.

22. The negative electrode tab of claim 19 wherein the protective layer has a porosity of 2% -50%.

23. The negative electrode tab of claim 19 wherein the protective layer has a porosity of 15% -35%.

24. The negative electrode tab of claim 19, wherein the protective layer has a thickness of 1 μm to 30 μm.

25. The negative electrode tab of claim 19, wherein the protective layer has a thickness of 1 μm to 15 μm.

26. The negative electrode pad of claim 19, wherein the protective layer comprises at least one of a first material comprising at least one of lithium sulfide, aluminum sulfide, phosphorus sulfide, silicon sulfide, titanium sulfide, or tin sulfide, polyethylene oxide, polypropylene oxide, polyvinylidene chloride, polyvinylidene fluoride, lithium lanthanum zirconium oxide, lanthanum lithium titanate, or a fast ion conductor.

27. The anode electrode tab according to claim 1 or 2, wherein the mass ratio of the second anode active material layer is 1% -25% based on the total mass of the anode active material layer.

28. The anode electrode tab according to claim 1 or 2, wherein the mass ratio of the second anode active material layer is 3% -15% based on the total mass of the anode active material layer.

29. The negative electrode tab of claim 1 or 2, wherein the current collector has oppositely disposed first and second surfaces, each of the first and second surfaces comprising first and second regions, the first regions of the first surface and the first regions of the second surface being symmetrically disposed.

30. A method of making the negative electrode sheet of any one of claims 1-29, comprising:

31. The method of claim 30, wherein forming a silicon-based material in the second region of the current collector comprises:

forming a conductive layer in the second region;

32. The method as recited in claim 30, further comprising: and forming a protective layer on one side of the active metal ion supplementing layer, which is away from the current collector.

33. A battery comprising the negative electrode sheet of any one of claims 1-29 or the negative electrode sheet prepared by the method of any one of claims 30-32.

34. A powered device comprising the battery of claim 33.