阅读说明：本技术 一种隔膜及其制备方法、锂离子电池 (Diaphragm, preparation method thereof and lithium ion battery ) 是由 李杨 欧阳林 王芳 柳志民 刘东秦 于 2019-09-25 设计创作，主要内容包括：本发明提供一种隔膜及其制备方法、锂离子电池,其中,所述隔膜包括基材层、补锂层及位于所述基材层与所述补锂层之间的处理层,所述处理层具有亲锂性。本发明提供的方案解决了现有的隔膜拉伸强度低及表面不平整的问题。(The invention provides a diaphragm, a preparation method thereof and a lithium ion battery, wherein the diaphragm comprises a substrate layer, a lithium supplement layer and a treatment layer positioned between the substrate layer and the lithium supplement layer, and the treatment layer has lithium affinity. The scheme provided by the invention solves the problems of low tensile strength and uneven surface of the existing diaphragm.)

1. The diaphragm is applied to a lithium ion battery and is characterized by comprising a substrate layer, a lithium supplementing layer and a processing layer located between the substrate layer and the lithium supplementing layer, and the processing layer has lithium affinity.

2. The separator of claim 1, wherein the handle layer comprises a lithium-philic functional group.

3. The separator according to claim 2, wherein the lithium-philic functional group is a nitrogen-containing functional group.

4. The membrane of claim 3, wherein the nitrogen-containing functional group is at least one of a pyridine nitrogen, a pyrrole nitrogen, a diazo compound, and an azo compound.

5. The membrane of claim 1, further comprising a first ceramic layer positioned between the substrate layer and the handle layer and a second ceramic layer positioned on a side of the substrate layer opposite the first ceramic layer.

6. The separator of claim 5, wherein the first ceramic layer comprises at least one of alumina, boehmite, polyvinylidene fluoride, and polymethyl methacrylate, and the second ceramic layer comprises at least one of alumina, boehmite, polyvinylidene fluoride, and polymethyl methacrylate.

7. The membrane of claim 1, wherein the substrate layer comprises at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyester, polyimide, polyamide, cellulose, aramid, spandex.

8. Separator according to claim 1, wherein the thickness of the treatment layer is 0.05-200 μm.

9. The separator according to claim 1, wherein the thickness of the base material layer is 5 to 200 μm.

10. The separator according to claim 1, wherein the thickness of the lithium supplement layer is 0.1 to 200 μm.

11. A lithium ion battery comprising a positive electrode, a negative electrode and the separator according to any one of claims 1 to 10, wherein the lithium supplement layer on the separator faces the negative electrode.

12. A method for preparing a separator, comprising the steps of:

pretreating a base material to form a treatment layer with lithium affinity on the surface of the base material;

and carrying out lithium deposition treatment on one side of the substrate to form a lithium supplement layer.

13. The production method according to claim 12, wherein the step of pretreating the substrate to form a treated layer having lithium-philic property on the surface of the substrate comprises:

the method comprises the step of pretreating a substrate in a nitrogen environment to form a treatment layer containing nitrogen functional groups on the surface of the substrate.

14. The method of claim 13, wherein the pre-treatment is corona treatment at a voltage of 1-10kV, a current of 0.1-10mA, and a speed of 1-50 m/min.

15. The production method according to claim 13, wherein the pretreatment is a plasma treatment, and a treatment time of the plasma treatment is 1 to 200 min.

16. The method according to claim 12, wherein the step of subjecting one surface of the substrate to a lithium deposition treatment to form a lithium supplement layer comprises:

performing lithium deposition treatment on one surface of the substrate by adopting an evaporation coating process to form a lithium supplement layer;

wherein the arc current of the evaporation coating is 10-150A, the temperature is 100-500 ℃, and the vacuum pressure is 10^-1-10^-4Pa, time is 1-500 min.

17. The method according to claim 12, wherein the step of subjecting one surface of the substrate to a lithium deposition treatment to form a lithium supplement layer comprises:

performing lithium deposition treatment on one surface of the substrate by adopting a magnetron sputtering process to form a lithium supplement layer;

wherein the rotation speed of magnetron sputtering is 1-50rpm, the heating temperature is 50-800 ℃, and the vacuum degree is 0.0000001-0.1 Pa.

Technical Field

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

Background

Lithium ion batteries are widely used in the fields of digital, energy storage, electric vehicles and the like due to their characteristics of high energy density, high voltage, long cycle life and the like. In the case of a lithium ion battery, active lithium of a positive electrode is consumed due to the generation of a Solid Electrolyte film (SEI) during the first charge and discharge process, so that the lithium content of the lithium ion battery is reduced after the first charge.

In contrast, lithium ion batteries need to be replenished with lithium. At present, the common lithium supplementing technology is to directly spread a lithium strip on a diaphragm by a dry powder lithium method and then form a composite diaphragm by cold pressing, or to compound a lithium strip and the diaphragm by the cold pressing method, however, the methods are easy to cause the problems of low tensile strength and uneven surface of the compounded diaphragm.

Disclosure of Invention

The embodiment of the invention provides a diaphragm, a preparation method thereof and a lithium ion battery, and aims to solve the problems of low tensile strength and uneven surface of the existing diaphragm.

In order to solve the problems, the invention is realized as follows:

in a first aspect, an embodiment of the present invention provides a separator, which is applied to a lithium ion battery, where the separator includes a substrate layer, a lithium supplement layer, and a treatment layer located between the substrate layer and the lithium supplement layer, and the treatment layer has lithium affinity.

Optionally, the handle layer includes a lithium-philic functional group therein.

Optionally, the lithium-philic functional group is a nitrogen-containing functional group.

Optionally, the nitrogen-containing functional group is at least one of pyridine nitrogen, pyrrole nitrogen, diazo compound, and azo compound.

Optionally, the membrane further comprises a first ceramic layer and a second ceramic layer, the first ceramic layer is located between the substrate layer and the treatment layer, and the second ceramic layer is located on a side of the substrate layer opposite to the first ceramic layer.

Optionally, the first ceramic layer includes at least one of alumina, boehmite, polyvinylidene fluoride, and polymethyl methacrylate, and the second ceramic layer includes at least one of alumina, boehmite, polyvinylidene fluoride, and polymethyl methacrylate.

Optionally, the substrate layer comprises at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyester, polyimide, polyamide, cellulose, aramid, and spandex.

Optionally, the thickness of the treatment layer is 0.05-200 μm.

Optionally, the thickness of the substrate layer is 5-200 μm.

Optionally, the lithium supplement layer has a thickness of 0.1 to 200 μm.

In a second aspect, an embodiment of the present invention further provides a lithium ion battery, including a positive electrode, a negative electrode, and the separator in any one of the first aspect, where a lithium supplement layer on the separator faces the negative electrode.

In a third aspect, an embodiment of the present invention further provides a preparation method of a separator, including the following steps:

pretreating a base material to form a treatment layer with lithium affinity on the surface of the base material;

and carrying out lithium deposition treatment on one side of the substrate to form a lithium supplement layer.

Optionally, the step of pretreating the substrate to form a treatment layer having lithium-philic property on the surface of the substrate includes:

the method comprises the step of pretreating a substrate in a nitrogen environment to form a treatment layer containing nitrogen functional groups on the surface of the substrate.

Optionally, the pretreatment is corona treatment, wherein the voltage of the corona treatment is 1-10kV, the current is 0.1-10mA, and the speed is 1-50 m/min.

Optionally, the pretreatment is a plasma treatment, and the treatment time of the plasma treatment is 1-200 min.

Optionally, the step of subjecting one side of the substrate to a lithium deposition treatment to form a lithium supplement layer includes:

performing lithium deposition treatment on one surface of the substrate by adopting an evaporation coating process to form a lithium supplement layer;

wherein the arc current of the evaporation coating is 10-150A, the temperature is 100-500 ℃, and the vacuum pressure is 10^-1-10^-4Pa, time is 1-500 min.

Optionally, the step of subjecting one side of the substrate to a lithium deposition treatment to form a lithium supplement layer includes:

performing lithium deposition treatment on one surface of the substrate by adopting a magnetron sputtering process to form a lithium supplement layer;

wherein the rotation speed of magnetron sputtering is 1-50rpm, the heating temperature is 50-800 ℃, and the vacuum degree is 0.0000001-0.1 Pa.

The diaphragm provided by the invention comprises a lithium supplementing layer and a processing layer positioned between the substrate layer and the lithium supplementing layer on one side of the substrate layer, and the processing layer has lithium affinity. The lithium supplement layer can obviously improve the first charge and discharge efficiency of the diaphragm so as to improve the electrical property of the lithium ion battery; in addition, because the processing layer with the lithium affinity is formed on the base material layer, the lithium affinity of the base material layer is improved, and further when the lithium deposition processing is carried out on the base material layer, the deposition of metal lithium is facilitated, the base material layer is more smooth, the fiber structure inside the base material layer is full of lithium metal particles, the particles are mutually attracted through van der Waals force, and the tensile strength of the diaphragm is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

FIG. 1 is a block diagram of a diaphragm provided in accordance with an embodiment of the present invention;

FIG. 2a is an electron microscope scanning image of the surface layer of the base material in the membrane without pretreatment;

FIG. 2b is an electron microscope scanning image of the surface layer of the substrate in the pretreated diaphragm according to the embodiment of the present invention;

FIG. 3a is an electron microscope scanning image of a lithium supplement layer in a separator without pretreatment;

FIG. 3b is an electron microscope scanning image of a lithium supplement layer in a pretreated diaphragm according to an embodiment of the present invention;

fig. 4 is a structural view of another separator according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention provides a preparation method of a diaphragm, which comprises the following steps:

pretreating a base material to form a treatment layer with lithium affinity on the surface of the base material;

and carrying out lithium deposition treatment on one side of the substrate to form a lithium supplement layer.

Alternatively, the substrate may be at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyester, polyimide, polyamide, cellulose, aramid, spandex. For example, a polypropylene microporous film may be selected as the substrate, and the substrate may be subjected to a pretreatment in a nitrogen atmosphere to form a treatment layer having lithium-philic properties on the surface layer of the substrate. Therefore, the processing layer of the diaphragm has lithium affinity so as to increase the adsorption capacity between the base material layer and the lithium supplement layer.

Alternatively, the lithium-philic property of the handle layer may be the formation of a lithium-philic functional group, such as a nitrogen-containing functional group, in the handle layer. In one specific implementation, the substrate may be pretreated in a nitrogen environment to form a treated layer containing nitrogen functional groups on the surface of the substrate.

For example, the pretreatment may be corona treatment or plasma treatment, so that the chemical bond of the compound in the surface layer substrate is opened to combine with nitrogen element in nitrogen gas to form a compound containing a nitrogen functional group, such as pyridine nitrogen, pyrrole nitrogen, diazo compound, azo compound, or the like, or at least one of these compounds. Thus, the surface layer substrate including the nitrogen-containing functional group also forms a treated layer, that is, the treated layer may be formed by treating the surface layer of the substrate.

Of course, the pretreatment may be additionally applying a substance containing a nitrogen-containing functional group to one side of the substrate. Optionally, the pretreatment is corona treatment, wherein the voltage of the corona treatment is 1-10kV, the current is 0.1-10mA, and the speed is 1-50 m/min. Or the pretreatment can also be plasma treatment, and the treatment time of the plasma treatment is 1-200 min.

In addition, one side of the pretreated base material is subjected to lithium deposition treatment by adopting an evaporation lithium plating process to form a lithium supplement layer; wherein the arc current of the evaporation coating is 10-150A, the temperature is 100-500 ℃, and the vacuum pressure is 10^-1～10^-4Pa, for 1-500 min. Or, performing lithium deposition treatment on one surface of the pretreated substrate by adopting a magnetron sputtering process to form a lithium supplement layer; wherein the rotation speed of magnetron sputtering is 1-50rpm, the heating temperature is 50-800 ℃, and the vacuum degree is 0.0000001-0.1 Pa.

The following will specifically explain the method of producing the separator in examples 1 and 2.

Example 1

Selecting a polypropylene microporous film as a base material of the diaphragm, and carrying out corona treatment on the base material in a nitrogen environment, wherein the voltage of the corona treatment is 5kV, the current is 2mA, and the speed is 20m/min, so that a chemical bond of a compound in the surface layer of the base material is opened to be combined with a nitrogen element in nitrogen to form a compound containing a nitrogen functional group; forming a processing layer including a nitrogen-containing functional group on a surface layer of a substrate, and subjecting the diaphragm substrate including the processing layer to XPS (X-ray photoelectron spectroscopy) test, wherein test results are shown in table 1; while the barrier including the treatment layerThe membrane substrate is fixed on a sample rack of a vacuum coating machine, high-purity lithium foil is selected as an evaporation source to carry out evaporation lithium plating on one surface of the membrane substrate, the arc current of the evaporation lithium plating is 10-150A, the temperature is 100-500 ℃, and the vacuum pressure is 10^-1-10^-4Pa, the time is 1-500min, the thickness of the lithium supplement layer is 2 mu m, and then a diaphragm with one side plated with lithium is prepared, and the diaphragm is tested for the tensile strength in the transverse direction and the longitudinal direction. Further, the diaphragm, a ternary positive electrode, a lithium ion battery electrolyte and a silicon-carbon negative electrode form a lithium ion battery, wherein the lithium-plated surface of the diaphragm faces the negative electrode, the electrolyte is injected and stands for 24 hours, then the first charging efficiency is tested, and the test results are shown in table 2.

Example 2

Selecting polyethylene as a base material of a diaphragm, coating ceramic layers on two sides of the base material of the diaphragm, placing the base material coated with the ceramic layers on the two sides in plasma treatment equipment for plasma surface treatment, wherein working gas is compressed nitrogen, the treatment time is 30min, so that a treatment layer comprising nitrogen-containing functional groups is formed on the surface layer of the base material, and performing XPS (X-ray diffraction) test on the base material of the diaphragm comprising the treatment layer, wherein the test results please refer to Table 1; and then, plating lithium on one surface of the diaphragm substrate comprising the treatment layer by utilizing a magnetron sputtering process, wherein the rotation speed of magnetron sputtering is 25rpm, the heating temperature is 200 ℃, the vacuum degree is 0.000008Pa, the thickness of the lithium supplement layer is 3 mu m, the diaphragm is tested for the transverse and longitudinal tensile strength, meanwhile, the diaphragm, a ternary positive electrode, lithium ion battery electrolyte and a silicon-carbon negative electrode form a lithium ion battery, wherein the lithium plating surface of the diaphragm faces to the negative electrode, the first charging efficiency is tested after the electrolyte is injected and stands for 24 hours, and the test results please refer to Table 2.

For reference, the present invention also provides two conventional methods for preparing a separator as comparative examples.

Comparative example 1

Forming a lithium ion battery by using a polypropylene microporous diaphragm, a ternary positive electrode, a silicon-carbon negative electrode and a lithium ion battery electrolyte; after the electrolyte is injected and stands for 24 hours, testing the charging efficiency for the first time, carrying out XPS (X-ray diffraction) testing on the diaphragm, and simultaneously testing the transverse tensile strength and the longitudinal tensile strength of the diaphragm, wherein the test results are shown in tables 1 and 2 respectively.

Comparative example 2

Selecting polyethylene as a base material of the diaphragm, coating ceramic on two sides of the diaphragm, and forming a lithium ion battery together with a ternary anode, a silicon-carbon cathode and lithium ion battery electrolyte; after the electrolyte is injected and stands for 24 hours, testing the charging efficiency for the first time, carrying out XPS (X-ray diffraction) testing on the diaphragm, and simultaneously testing the transverse tensile strength and the longitudinal tensile strength of the diaphragm, wherein the test results are shown in tables 1 and 2 respectively.

TABLE 1 XPS test results for different membranes

TABLE 2 test results of first charge efficiency, transverse and longitudinal tensile strength of different separators

As can be seen from table 1, the content of N element in the separator provided by the example of the present invention is significantly increased after the separator is pretreated, compared to the conventional common separators (comparative example 1 and comparative example 2). The N element has better lithium affinity, and the increase of the N element also enables the surface layer of the base material to have lithium affinity, thereby being more beneficial to the deposition of lithium in the lithium supplementing layer and improving the surface smoothness of the diaphragm.

Please refer to table 2, compared with the existing common separator (comparative example 1 and comparative example 2), after the separator provided by the embodiments 1 and 2 of the present invention is pretreated, the transverse tensile strength and the longitudinal tensile strength of the separator are both significantly improved, so that the stability of the separator in the lithium ion battery is better, and the service life of the separator is also increased. In addition, as can also be seen from table 2, after the separators provided in embodiments 1 and 2 of the present invention are pretreated, the first charging efficiency is also significantly improved, and further, the electrical properties of the lithium ion battery are improved.

In addition, in the process of preparing the diaphragm, the thickness of the lithium supplement layer can be selectively adjusted by adjusting the technological parameters of the lithium deposition treatment, such as the time of evaporating and plating lithium. In the present invention, the thickness of the lithium supplement layer may be 0.1 to 200. mu.m. In addition, the thickness of the base material layer is 5-200 μm; the thickness of the treatment layer is 0.05-200 μm. Therefore, the whole thickness of the diaphragm can be selectively adjusted, and the diaphragm is more favorable for being applied to lithium ion batteries of different types and different purposes.

The embodiment of the invention also provides a diaphragm applied to the lithium ion battery, as shown in fig. 1, the diaphragm comprises a substrate layer 1, a lithium supplement layer 3 and a treatment layer 2 positioned between the substrate layer 1 and the lithium supplement layer 3, and the treatment layer 2 has lithium affinity.

The lithium ion battery comprises a positive electrode and a negative electrode, and the separator is positioned between the positive electrode and the negative electrode and plays a role in isolation and insulation between the positive electrode and the negative electrode.

The lithium ion battery realizes charge and discharge by the back-and-forth movement of lithium ions between the anode and the cathode, so that the quantity of the lithium ions plays a decisive role in the charge and discharge capacity of the lithium ion battery. Since the lithium ion battery consumes active lithium of the positive electrode due to the formation of the SEI film after the first charge, the amount of lithium ions in the lithium ion battery decreases after the first charge.

In the embodiment of the invention, the diaphragm comprises the lithium supplement layer 3, the lithium supplement layer 3 is positioned on one side of the substrate layer 1 facing the negative electrode, the lithium supplement layer 3 can react with the negative electrode to form an SEI film on the surface of the negative electrode, and further when the lithium ion battery is charged for the first time, the SEI film is formed on the surface of the negative electrode, so that active lithium of the positive electrode is not required to be consumed, the lithium ion quantity of the lithium ion battery can be ensured, and the charge and discharge capacity of the lithium ion battery can be ensured. The lithium supplement layer 3 may be a lithium compound or metallic lithium.

In addition, the separator provided by the embodiment of the invention comprises the treatment layer 2 between the lithium supplement layer 3 and the substrate layer 1, and the treatment layer 2 has lithium affinity, so that the adsorption capacity between the substrate layer 1 and the lithium supplement layer 3 is increased.

In this embodiment, the treatment layer 2 includes a lithium-philic functional group. The lithium-affinity of the substrate layer 1 is improved due to the arrangement of the lithium-affinity functional groups, and the adsorption capacity between the substrate layer 1 and the lithium supplement layer 3 is improved.

Optionally, the lithium-philic functional group is a nitrogen-containing functional group. The treatment layer 2 may be formed by subjecting the substrate to a pretreatment such as corona treatment or plasma treatment in a nitrogen atmosphere, so that the chemical bonds of the compounds in the surface substrate are opened to combine with nitrogen elements in the nitrogen gas to form a compound containing a nitrogen functional group, such as pyridine nitrogen, pyrrole nitrogen, diazo compound, azo compound, or at least one of these compounds. Thus, the treated layer 2 is formed on the surface layer substrate including the nitrogen-containing functional group, that is, the treated layer 2 may be formed by treating the surface layer of the substrate, as in the process described in example 1 of the above-described method for manufacturing a separator. Of course, the treatment layer 2 may be a substance additionally containing a nitrogen-containing functional group applied to one side of the substrate.

In the present embodiment, the formation of the treated layer 2 by treating the surface of the base material will be described as an example. Referring to fig. 2a, fig. 2b, fig. 3a and fig. 3b, fig. 2a is an electron microscope scan of a surface layer of a substrate in a non-pretreated diaphragm, fig. 2b is an electron microscope scan of a surface layer of a substrate in a pretreated diaphragm, fig. 3a is an electron microscope scan of a lithium supplement layer in a non-pretreated diaphragm, and fig. 3b is an electron microscope scan of a lithium supplement layer in a pretreated diaphragm.

As can be seen by comparing FIG. 2a with FIG. 2b, the surface of the pretreated substrate is relatively flat (shown in FIG. 2 b), while the surface of the substrate without pretreatment is relatively rough (shown in FIG. 2 a); as can be seen from a comparison between fig. 3a and fig. 3b, the surface of the lithium supplement layer in the pretreated diaphragm is relatively flat, the particles are relatively complete, and the distance between the particles is relatively small (shown in fig. 3 b), while the surface of the lithium supplement layer in the untreated diaphragm is relatively rough, and the distance between the particles is relatively large (shown in fig. 3 a). That is to say, through carrying out the preliminary treatment to the top layer of substrate, form the nitrogenous functional group for the substrate top layer has had lithium affinity nature, more is favorable to mending the deposit of lithium in the lithium layer, and under the adsorption efficiency of nitrogenous functional group, the inside fibrous structure of substrate top layer after the preliminary treatment has been covered with lithium metal particle, makes the substrate top layer more level and more smooth.

The lithium supplement layer 3 may be formed on the surface layer of the pretreated substrate by an evaporation lithium plating process or a magnetron sputtering process, and specifically, reference may be made to example 1 and example 2 in the above-described method for preparing the separator. The diaphragm provided by the invention is characterized in that a processing layer 2 comprising nitrogen-containing functional groups is formed on the surface layer of the substrate by pretreating the surface layer of the substrate, and a lithium-supplementing layer 3 is formed by carrying out lithium deposition treatment, such as evaporation lithium plating or magnetron sputtering, on one side of the pretreated surface layer of the substrate, so as to obtain the diaphragm plated with lithium on one side in the embodiment of the invention. Therefore, the first charge and discharge efficiency of the diaphragm can be obviously improved, and the electrical property of the lithium ion battery can be further improved; in addition, because the processing layer 2 comprising the nitrogen-containing functional group is formed on the surface layer of the substrate, the lithium affinity of the surface layer of the substrate is improved, and further, when the surface layer of the substrate is subjected to lithium deposition processing, the deposition of metal lithium is more facilitated, the fiber structure in the surface layer of the substrate is full of lithium metal particles, and the particles are mutually attracted through Van der Waals force, so that the tensile strength of the diaphragm is improved.

As an alternative implementation manner of the embodiment of the present invention, referring to fig. 4, the separator may further include a first ceramic layer 41 and a second ceramic layer 42, where the first ceramic layer 41 is located between the substrate layer 1 and the processing layer 2, and the second ceramic layer 42 is located on a side of the substrate layer 1 opposite to the first ceramic layer 41. Alternatively, the first ceramic layer 41 includes at least one of alumina, boehmite, polyvinylidene fluoride, and polymethyl methacrylate, and the second ceramic layer 42 includes at least one of alumina, boehmite, polyvinylidene fluoride, and polymethyl methacrylate. The first ceramic layer 41 and the second ceramic layer 42 may be made of the same material or different materials. The arrangement of the ceramic layer can improve the thermal stability of the diaphragm, so that the lithium ion battery is ensured to have better cycle thermal stability, and the service life and the thermal safety of the lithium ion battery are ensured.

In the embodiment of the present invention, the material of the substrate layer 1 may be at least one of polypropylene, polyethylene, polyvinylidene fluoride, polyester, polyimide, polyamide, cellulose, aramid, and spandex. In the above method for producing a separator, polypropylene or polyethylene is selected as the separator base material.

Alternatively, the thickness of the substrate layer 1 may be selected to be between 5 μm and 200 μm, and may specifically be determined according to the model, applicable scenario, and the like of the lithium ion battery.

In addition, the thickness of the lithium supplement layer 3 is 0.1-200 μm; the thickness of the treatment layer 2 is 0.05-200 μm, and may be determined according to the model of the lithium ion battery, the applicable scene, and the like.

The embodiment of the invention also provides a lithium ion battery which comprises a positive electrode, a negative electrode and the diaphragm, wherein the lithium supplement layer on the diaphragm faces to the negative electrode. The lithium ion battery provided by the embodiment of the invention comprises all the technical characteristics in the diaphragm embodiment, can achieve the same technical effect, and is not repeated herein to avoid repetition.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.