CN112259706A

CN112259706A - Pre-lithiation pole piece, preparation method of pre-lithiation pole piece and lithium ion battery

Info

Publication number: CN112259706A
Application number: CN202011002744.9A
Authority: CN
Inventors: 臧伟; 龙国斌; 蔡春亮
Original assignee: Advanced Precision Technology Co ltd
Current assignee: Advanced Precision Technology Co ltd
Priority date: 2020-09-22
Filing date: 2020-09-22
Publication date: 2021-01-22

Abstract

The invention discloses a pre-lithiation pole piece, a preparation method of the pre-lithiation pole piece and a lithium ion battery, and relates to the technical field of lithium ion batteries; the preparation method of the prelithiation pole piece comprises the following steps: s1, preparing a metal film; s2, forming a sandwich-shaped film; s3, forming a metal lithium layer, and etching a plurality of to-be-plated areas distributed in an array manner on the surfaces of the upper and lower layers of film substrates by adopting an ion milling technology, wherein the to-be-plated areas penetrate through the film substrates and the active material layer; plating metal lithium on the surface of the film base material, filling the region to be plated with the metal lithium, and forming a metal lithium layer on the outer surface of the film base material; s4, peeling the film substrate, namely peeling the film substrate on the upper surface of the metal film and the active material layer, and peeling the film substrate on the lower surface of the metal film and the active material layer to obtain a pre-lithiation pole piece; the invention has the beneficial effects that: the safety performance is higher, can also provide the lithium source far away for the lithium cell, has realized the perfect balance of safety and energy density.

Description

Pre-lithiation pole piece, preparation method of pre-lithiation pole piece and lithium ion battery

Technical Field

The invention relates to the technical field of lithium ion batteries, in particular to a prelithiation pole piece, a preparation method of the prelithiation pole piece and a lithium ion battery.

Background

In the first charging process of the polymer lithium battery, the organic electrolyte is reduced and decomposed on the surface of a negative electrode such as graphite to form a Solid Electrolyte Interface (SEI) film, so that a large amount of lithium from a positive electrode is permanently consumed, the initial cycle coulombic efficiency (ICE) is low, and the capacity and energy density of the polymer lithium battery are reduced. In order to solve the problem, people begin to research the prelithiation technology, and through continuous research, the current prelithiation process mainly comprises the following four methods, namely an electrochemical prelithiation method, a chemical prelithiation method, a metal lithium patch method and a stable metal lithium powder method.

The existing processes adopting the methods can realize the function of lithium supplement for the lithium ion battery, but due to the defects of the processes, the continuous lithium supplement for the lithium ion battery cannot be realized, and the safety performance and the strength are not good.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a prelithiation pole piece, a preparation method of the prelithiation pole piece and a lithium ion battery, and aims to solve the problems that in the prior art, a lithium supplement pole piece cannot realize continuous lithium supplement, and the safety performance and the strength are insufficient.

The technical scheme adopted by the invention for solving the technical problems is as follows: the improvement of a preparation method of a prelithiation pole piece is that the preparation method comprises the following steps:

s1, preparing a metal film, namely plating metal layers on two surfaces of a film substrate respectively to form the metal film, coating active material slurry on the upper surface and the lower surface of the metal film, and baking the active material slurry to form an active material layer;

s2, forming the sandwich-shaped film, namely taking two film base materials, respectively arranging the two film base materials on an active material layer on the upper surface and an active material layer on the lower surface of the metal film, and compounding the two film base materials through a coating compounding machine to form the sandwich-structured film;

s3, forming a metal lithium layer, and etching a plurality of to-be-plated areas distributed in an array manner on the surfaces of the upper and lower layers of film substrates by adopting an ion milling technology, wherein the to-be-plated areas penetrate through the film substrates and the active material layer; plating metal lithium on the surface of the film base material, filling the region to be plated with the metal lithium, and forming a metal lithium layer on the outer surface of the film base material;

and S4, stripping the film substrate, namely stripping the film substrate on the upper surface of the metal film and the active material layer and the film substrate on the lower surface of the metal film and the active material layer by adopting a stripping machine, and forming a plurality of lithium supplement regions distributed in an array on the active material layer to obtain the pre-lithiation pole piece.

Further, in step S1, metal layers are respectively coated on both surfaces of the film substrate by vacuum coating, and the active material slurry is coated on the upper and lower surfaces of the metal film by a coating and laminating apparatus.

Further, in the step S1 and the step S2, the film substrate is PP, PE or PET, and the thickness of the film substrate is 3 to 4 μm.

Furthermore, the metal layer is a copper layer, and the thickness of the metal layer is 600-1000 nm.

Further, in the step S1, the baking temperature is 80-90 ℃, and the baking time is 1-2 minutes.

Further, after the step S2, a step of aging the sandwich structure film at a high temperature is further included.

Further, in step S3, the thickness of the metal lithium layer on the outer surface of the film substrate is 100-200 nm.

Further, in step S4, the lithium supplement regions are rectangular, the length of each lithium supplement region is 100nm, the width of each lithium supplement region is 30nm, and the distance between adjacent lithium supplement regions is 20-30 nm.

Further, in step S4, the thickness of the active material layer and the lithium supplement region is the same, and is 50-100 nm.

Further, the step S4 is followed by the step of:

and S5, forming a protective layer, namely coating the protective layer on the outer surface of the active material layer and the lithium supplement region under the condition of dry inert gas, wherein the protective layer is porous nano zirconia.

Further, the thickness of the protective layer is 1-2 μm.

In addition, the invention also provides a pre-lithiation pole piece, and the improvement is as follows: comprises a film substrate, a metal layer, an active material layer and a lithium supplement area;

the upper surface and the lower surface of the film base material are respectively plated with a metal layer, an active material layer is attached to the outer surface of the metal layer, through holes penetrating through the active material layer are distributed in an array mode, the lithium supplementing area is arranged in the through holes of the active material layer, and the lithium supplementing area is in contact with the outer surface of the metal layer.

Furthermore, the lithium supplementing area is rectangular, and the length of the rectangle is more than three times of the distance between the adjacent lithium supplementing areas.

Furthermore, the length of the lithium supplement region is 100nm, the width of the lithium supplement region is 30nm, and the distance between adjacent lithium supplement regions is 20-30 nm.

Further, the thickness of the active material layer is the same as that of the lithium supplement region and is 50-100 nm.

Furthermore, protective layers are arranged on the outer surfaces of the active material region and the lithium supplement region, and the protective layers are made of porous nano zirconia.

Further, the thickness of the protective layer is 1-2 μm.

Furthermore, the material of the lithium supplement area is metal lithium.

Furthermore, the material of the film base material is PP, PE or PET.

Further, the thickness of the film substrate is 3-4 μm.

In addition, the invention also provides a lithium ion battery, and the improvement is that the negative pole piece of the lithium ion battery is obtained by the preparation method of the pre-lithiation pole piece.

The invention has the beneficial effects that: compared with the traditional lithium ion battery method of supplementing lithium by spraying Li powder in an electrostatic control mode and covering a thin Li foil layer on the surface of a negative electrode and directly using metal lithium as the negative electrode, the lithium ion battery has higher safety performance, can provide rich lithium sources for the lithium ion battery, realizes perfect balance of safety and energy density, and greatly improves the strength of a pole piece by adopting the mode of alternately arranging the active material area and the lithium supplementing area and coating porous nano zirconium oxide on the surface of the lithium supplementing area.

Drawings

Fig. 1 is a schematic flow chart of a method for preparing a pre-lithiated pole piece according to the present invention.

Fig. 2 is a schematic structural view of the metal thin film coated with the active material slurry according to the present invention.

FIG. 3 is a schematic cross-sectional view of a sandwich-shaped membrane of the present invention.

Fig. 4 is a schematic structural view of the lithium metal layer of the present invention after forming.

FIG. 5 is a schematic view of the structure of the film substrate of the present invention after peeling.

Fig. 6 is a schematic structural diagram of a pre-lithiated pole piece after the protective layer is formed according to the present invention.

Fig. 7 is a schematic structural diagram of the surface of the active material layer of the prelithiation pole piece of the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

The conception, the specific structure, and the technical effects produced by the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings to fully understand the objects, the features, and the effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention. In addition, all the connection/connection relations referred to in the patent do not mean that the components are directly connected, but mean that a better connection structure can be formed by adding or reducing connection auxiliary components according to specific implementation conditions. All technical characteristics in the invention can be interactively combined on the premise of not conflicting with each other.

Example 1

Referring to fig. 1, the invention discloses a preparation method of a pre-lithiation pole piece, and the pre-lithiation pole piece prepared by the preparation method can overcome the problems that a lithium supplement pole piece in the prior art cannot realize continuous lithium supplement and has insufficient safety performance and strength. Specifically, the method for preparing the prelithiation pole piece in this embodiment includes the following steps:

s1, preparing a metal film, namely respectively plating metal layers 20 on two sides of a film substrate 10 to form the metal film, coating active material slurry on the upper surface and the lower surface of the metal film, and baking the active material slurry at the baking temperature of 80 ℃ for 2 minutes; the active material slurry forms the active material layer 30; as shown in fig. 2, which is a schematic cross-sectional view of the semi-finished product obtained in step S1;

in the scheme, a vacuum coating method is adopted to coat metal layers 20 on two sides of a film base material 10 respectively, wherein the metal layers 20 are copper layers, and the thickness of the copper layers is 600 nm; coating the active material slurry on the upper surface and the lower surface of the metal film by adopting coating composite equipment; because the vacuum coating method and the coating composite equipment belong to the common technologies in the prior art, the vacuum coating method and the coating composite equipment are not explained in detail in the embodiment;

in addition, in step S1, the active material slurry is composed of the lithium-intercalatable active material, the conductive agent, the binder, and the solvent N-methylpyrrolidone, and the mass ratio of the active material slurry is 2: 1: 1: 2; the lithium-embeddable active material is one of artificial graphite, natural graphite, lithium titanate and a silicon-carbon material, the conductive agent is one of acetylene black and a carbon nano tube, and the binder is PVDF.

S2, forming the sandwich-shaped film, namely taking two film base materials 10, respectively arranging the two film base materials on the active material layer 30 on the upper surface and the active material layer 30 on the lower surface of the metal film, and compounding the two film base materials through a coating compounding machine to form the sandwich-structured film; in this embodiment, the film base 10 in step S1 and step S2 are the same and are both PET, and the thickness of the film base 10 is 3 μm; FIG. 3 is a schematic cross-sectional view of a sandwich-shaped film;

s3, forming a metal lithium layer, and etching a plurality of to-be-plated areas distributed in an array manner on the surfaces of the upper and lower layers of film substrates 10 by adopting an ion milling technology, wherein the to-be-plated areas penetrate through the film substrates 10 and the active material layer 30; plating metal lithium on the surface of the film base material 10, filling the region to be plated with the metal lithium, and forming a metal lithium layer 40 on the outer surface of the film base material 10; as shown in fig. 4, which is a schematic structural diagram of the formed lithium metal layer 40, the lithium metal layer 40 covers the film substrate 10 and can be directly contacted with the metal layer 30 after filling the region to be plated;

before step S3, a step of curing the sandwich structure film at a high temperature is further included, so as to etch a region to be plated on the surface of the film substrate 10;

in the step, the thickness of the metal lithium layer 40 on the outer surface of the film substrate 10 is 100 nm;

s4, peeling the film substrate 10, and peeling the film substrate 10 on the upper surface of the metal film and the active material layer 30 and the film substrate 10 on the lower surface of the metal film and the active material layer 30 by using a peeling machine to form a plurality of lithium supplement regions 401 distributed in an array on the active material layer 30 to obtain a pre-lithiation pole piece; as shown in fig. 5, which is a schematic structural diagram of the film substrate 10 after being peeled;

in this embodiment, the lithium supplement regions 401 are rectangular, the length of each lithium supplement region is 100nm, the width of each lithium supplement region is 30nm, and the distance between adjacent lithium supplement regions 401 is 20 nm; in addition, the thickness of the active material layer 30 is 50nm, which is the same as that of the lithium supplement region 401.

In addition, the step S4 is followed by the step of:

s5, forming a protective layer, namely coating the protective layer on the outer surface of the active material layer 30 and the lithium supplement region 401 under the condition of dry inert gas, wherein the protective layer is porous nano zirconia 60; the thickness of the protective layer was 1 μm. The porous carbon nano-film is applied to prevent the reaction between lithium metal and water in the air, and the porous nano-zirconia can increase the strength of the positive electrode sheet. As shown in fig. 6, the structure of the pre-lithiated electrode sheet after the formation of the protective layer is schematically illustrated.

Example 2

s1, preparing a metal film, namely respectively plating metal layers 20 on two sides of a film substrate 10 to form the metal film, coating active material slurry on the upper surface and the lower surface of the metal film, and baking the active material slurry at the baking temperature of 90 ℃ for 1 minute; the active material slurry forms the active material layer 30; as shown in fig. 2, which is a schematic cross-sectional view of the semi-finished product obtained in step S1;

in the scheme, a vacuum coating method is adopted to coat metal layers 20 on two sides of a film base material 10 respectively, wherein the metal layers 20 are copper layers, and the thickness of the copper layers is 1000 nm; coating the active material slurry on the upper surface and the lower surface of the metal film by adopting coating composite equipment; because the vacuum coating method and the coating composite equipment belong to the common technologies in the prior art, the vacuum coating method and the coating composite equipment are not explained in detail in the embodiment;

S2, forming the sandwich-shaped film, namely taking two film base materials 10, respectively arranging the two film base materials on the active material layer 30 on the upper surface and the active material layer 30 on the lower surface of the metal film, and compounding the two film base materials through a coating compounding machine to form the sandwich-structured film; in this embodiment, the film substrate 10 in step S1 and step S2 are the same and are both PE, and the thickness of the film substrate 10 is 4 μm; FIG. 3 is a schematic cross-sectional view of a sandwich-shaped film;

s3, forming a metal lithium layer 40, and etching a plurality of to-be-plated areas distributed in an array manner on the surfaces of the upper and lower layers of film substrates 10 by adopting an ion milling technology, wherein the to-be-plated areas penetrate through the film substrates 10 and the active material layer 30; plating metal lithium on the surface of the film base material 10, filling the region to be plated with the metal lithium, and forming a metal lithium layer 40 on the outer surface of the film base material 10; as shown in fig. 4, which is a schematic structural diagram of the formed lithium metal layer 40;

in the step, the thickness of the metal lithium layer 40 on the outer surface of the film substrate 10 is 200 nm;

s4, peeling the film substrate 10, and peeling the film substrate 10 on the upper surface of the metal film and the active material layer 30 and the film substrate 10 on the lower surface of the metal film and the active material layer 30 by using a peeling machine to form a plurality of lithium supplement regions 401 distributed in an array on the active material layer 30 to obtain a pre-lithiation pole piece 50; as shown in fig. 5, which is a schematic structural diagram of the film substrate 10 after being peeled;

in this embodiment, the lithium supplement regions 401 are rectangular, the length of each lithium supplement region is 100nm, the width of each lithium supplement region is 30nm, and the distance between adjacent lithium supplement regions 401 is 30 nm; in addition, the thickness of the active material layer 30 is 100nm, which is the same as that of the lithium supplement region 401.

In addition, the step S4 is followed by the step of:

s5, forming a protective layer, namely coating the protective layer on the outer surface of the active material layer 30 and the lithium supplement region 401 under the condition of dry inert gas, wherein the protective layer is porous nano zirconia 60; the thickness of the protective layer was 2 μm. The porous carbon nano-film is applied to prevent the reaction between lithium metal and water in the air, and the porous nano-zirconia can increase the strength of the positive electrode sheet. As shown in fig. 6, the structure of the pre-lithiated electrode sheet 50 after the formation of the protection layer is schematically illustrated.

Example 3

Based on the preparation method of the pre-lithiation pole piece, the invention provides a pre-lithiation pole piece, which is shown in fig. 6 and 7 and comprises a thin film substrate 10, a metal layer 20, an active material layer 30 and a lithium supplement area 401; the upper surface and the lower surface of the film base material 10 are both plated with metal layers 20, the material of the film base material 10 is PP, the thickness of the film base material is 3.5 mu m, the metal layers 20 are copper layers, and the thickness of the metal layers 20 is 800 nm. An active material layer 30 is attached to the outer surface of the metal layer 20, through holes are distributed in the active material layer 30 in an array mode, the lithium supplement region 401 is arranged in the through holes of the active material layer 30, and the lithium supplement region 401 is in contact with the outer surface of the metal layer 20; in this embodiment, the thickness of the active material layer 30 is the same as that of the lithium supplement region 401, and is 75 nm; the material of the lithium supplement region 401 is metal lithium.

The active material layer 30 is made of active material slurry, wherein the active material slurry is composed of lithium-embeddable active materials, a conductive agent, a binder and a solvent N-methylpyrrolidone, and the mass ratio of the active material slurry is 2: 1: 1: 2; the lithium-embeddable active material is one of artificial graphite, natural graphite, lithium titanate and silicon-carbon materials, the conductive agent is one of acetylene black and carbon nano tubes, and the binder is conventional PVDF.

As a preferred embodiment, as shown in fig. 7, the lithium supplement region 401 is rectangular, and the length of the rectangle is more than three times of the distance between adjacent lithium supplement regions 401; in this embodiment, the length of the lithium supplement region 401 is 100nm, the width thereof is 30nm, and the distance between adjacent lithium supplement regions 401 is 25 nm. In addition, protective layers are arranged on the outer surfaces of the active material region and the lithium supplement region 401, and the material of the protective layers is porous nano zirconia 60; the thickness of the protective layer is 1.5 μm.

Example 4

Based on the preparation method of the pre-lithiation pole piece, the invention provides a pre-lithiation pole piece, which is shown in fig. 6 and 7 and comprises a thin film substrate 10, a metal layer 20, an active material layer 30 and a lithium supplement area 401; the upper surface and the lower surface of the film base material 10 are both plated with metal layers 20, the material of the film base material 10 is PP, the thickness of the film base material is 3.75 micrometers, the metal layers 20 are copper layers, and the thickness of the metal layers 20 is 700 nm. An active material layer 30 is attached to the outer surface of the metal layer 20, through holes are distributed in the active material layer 30 in an array mode, the lithium supplement region 401 is arranged in the through holes of the active material layer 30, and the lithium supplement region 401 is in contact with the outer surface of the metal layer 20; in this embodiment, the thickness of the active material layer 30 is the same as that of the lithium supplement region 401, and is 80 nm; the material of the lithium supplement region 401 is metal lithium.

The active material layer 30 is made of active material slurry, and the active material slurry is composed of a lithium-embeddable active material, a conductive agent, a binder and a solvent N-methylpyrrolidone, wherein the lithium-embeddable active material is one of artificial graphite, natural graphite, lithium titanate and a silicon carbon material, the conductive agent is one of acetylene black and carbon nanotubes, and the binder is conventional PVDF.

As a preferred embodiment, as shown in fig. 7, the lithium supplement region 401 is rectangular, and the length of the rectangle is more than three times of the distance between adjacent lithium supplement regions 401; in this embodiment, the length of the lithium supplement region 401 is 100nm, the width thereof is 30nm, and the distance between adjacent lithium supplement regions 401 is 28 nm. In addition, protective layers are arranged on the outer surfaces of the active material region and the lithium supplement region 401, and the material of the protective layers is porous nano zirconia 60; the thickness of the protective layer is 1 μm.

Based on the embodiment, the invention also provides the lithium ion battery, and the negative pole piece of the lithium ion battery is obtained by the preparation method of the pre-lithiation pole piece.

Compared with the traditional lithium ion battery method of supplementing lithium by spraying Li powder in an electrostatic control mode and covering a thin Li foil layer on the surface of a negative electrode and directly using metal lithium as the negative electrode, the pre-lithiation pole piece has higher safety performance, can provide a far-continuous lithium source for the lithium ion battery, realizes perfect balance between safety and energy density, and greatly improves the strength of the pole piece by adopting the active material area and the lithium supplementing area 401 which are arranged at intervals and the way of coating the surface of the lithium supplementing area 401 with the porous nano zirconium oxide 60.

In addition, the invention also provides related data of the safety performance test and the energy density test.

The preparation of the experimental battery of the invention:

the cathode plate adopts the pre-lithiation pole plate, and the anode plate is composed of lithium iron phosphate, positive conductive agent acetylene black, binder PVDF and positive current collector aluminum foil; the electrolyte consists of lithium salt LiPF6, solvent dimethyl carbonate and additive fluoroethylene carbonate; and then, preparing the lithium ion battery according to a normal lithium ion battery production process.

Preparation of comparative example cell:

the active material is completely covered on the negative pole piece, the structure of the prelithiation pole piece is not provided, and the other parts are completely the same, so that the experimental battery of the comparative example is assembled.

The acupuncture experiment method comprises the following steps: after the battery is fully charged by adopting a conventional testing method, a high-temperature resistant steel needle with phi of 7mm penetrates through the battery from the direction vertical to a battery polar plate at the speed of 23mm/s, the steel needle stays in the battery for 1h, and the battery is qualified without abnormal phenomena.

Overcharge experiment: and (3) adopting a conventional test method, currently charging at 0.5 ℃ at 25 ℃ until the battery is half-full, then charging at a constant current of 1C multiplying power for 2h, and stopping, wherein the battery is qualified without smoking or fire.

The experimental data are as follows:

laboratory test article	Overcharge test	Acupuncture experiment
			1	No abnormal phenomenon	No smoke and fire
2	No abnormal phenomenon	No smoke and fire
			3	No abnormal phenomenon	No smoke and fire

The energy density test method comprises the following steps: standing the battery at room temperature of 25 ℃ for 30 minutes, then charging the battery to 4.35V at a constant current of 0.7C, and charging the battery at a constant voltage until the current is 0.05C; after standing for 3 minutes, the mixture was discharged at a constant current of 0.5C to 3.0V, and the energy at that time was measured. Wherein the calculation formula of the energy density is as follows: energy density is the energy of a battery divided by the volume of the battery.

The test data are as follows:

sample (I)	Energy density
		Experimental product 1	810Wh/L
Experimental product 2	823Wh/L
		Comparative example 1	730Wh/L
Comparative example 2	742Wh/L

And (3) testing the strength:

the prelithiation samples of the present invention were secured to clamps at the upper and lower ends of the tensile strength gauge. The tensile strength was measured at a rate of 100 mm/min. The tensile strength of the test piece at the time of tensile breaking was designated as kgf/cm2 by applying force in the upper and lower directions. The test results are shown in the following table.

Sample (I)	Tensile strength
		Experimental product 1	5.213
Experimental product 2	5.734
		Comparative example 1	3.445
Comparative example 2	3.673

By combining experimental data, the prelithiation pole piece adopting the method disclosed by the invention is better in the aspects of energy density, tensile strength and safety performance.

While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A preparation method of a pre-lithiation pole piece is characterized by comprising the following steps:

2. The method of claim 1, wherein in step S1, the metal layers are coated on both sides of the film substrate by vacuum coating, and the active material slurry is coated on the upper and lower surfaces of the metal film by a coating and laminating apparatus.

3. The method of claim 1, wherein in steps S1 and S2, the film substrate is PP, PE or PET, and the thickness of the film substrate is 3 to 4 μm.

4. The method as claimed in claim 3, wherein the metal layer is a copper layer and has a thickness of 600-1000 nm.

5. The method for preparing a pre-lithiated pole piece according to claim 1, wherein in the step S1, the baking temperature is 80-90 ℃ and the baking time is 1-2 minutes.

6. The method of claim 1, further comprising a step of aging the sandwich structure thin film at high temperature after step S2.

7. The method as claimed in claim 1, wherein in step S3, the thickness of the metal lithium layer on the outer surface of the film substrate is 100-200 nm.

8. The method of claim 1, wherein in step S4, the lithium supplement regions are rectangular, the length of each lithium supplement region is 100nm, the width of each lithium supplement region is 30nm, and the distance between adjacent lithium supplement regions is 20-30 nm.

9. The method of claim 1 or 8, wherein in step S4, the thickness of the active material layer is 50-100nm, which is the same as the thickness of the lithium supplement region.

10. The method for preparing a prelithiated pole piece according to claim 1, further comprising, after step S4:

11. The method of claim 10, wherein the protective layer has a thickness of 1-2 μm.

12. A prelithiation pole piece, characterized in that: comprises a film substrate, a metal layer, an active material layer and a lithium supplement area;

13. The prelithiation pole piece of claim 12, wherein: the lithium supplementing area is rectangular, and the length of the rectangle is more than three times of the distance between the adjacent lithium supplementing areas.

14. The prelithiation pole piece of claim 13, wherein: the length of the lithium supplement region is 100nm, the width of the lithium supplement region is 30nm, and the distance between adjacent lithium supplement regions is 20-30 nm.

15. The prelithiation pole piece of claim 12, wherein: the thickness of the active material layer is the same as that of the lithium supplement region and is 50-100 nm.

16. The prelithiation pole piece of claim 12, wherein: and protective layers are arranged on the outer surfaces of the active material region and the lithium supplement region, and the protective layers are made of porous nano zirconia.

17. The prelithiation pole piece of claim 16, wherein: the thickness of the protective layer is 1-2 μm.

18. The prelithiation pole piece of claim 12, wherein: the material of the lithium supplementing area is metal lithium.

19. The prelithiation pole piece of claim 12, wherein: the film base material is PP, PE or PET.

20. The prelithiation pole piece of claim 12, wherein: the thickness of the film substrate is 3-4 μm.

21. The prelithiation pole piece of claim 12, wherein: the metal layer is a copper layer, and the thickness of the metal layer is 600-1000 nm.

22. A lithium ion battery, characterized in that the negative electrode sheet of the lithium ion battery is obtained by the method for preparing a prelithiation electrode sheet according to any one of claims 1 to 11.