CN108075106B

CN108075106B - Preparation method of metal lithium negative electrode self-adaptive elastic nano-modification layer

Info

Publication number: CN108075106B
Application number: CN201711175663.7A
Authority: CN
Inventors: 郭玉国; 李念武; 殷雅侠
Original assignee: Institute of Chemistry CAS
Current assignee: Institute of Chemistry CAS
Priority date: 2017-11-22
Filing date: 2017-11-22
Publication date: 2020-12-15
Anticipated expiration: 2037-11-22
Also published as: CN108075106A

Abstract

The invention discloses a preparation method of a self-adaptive elastic nanometer modification layer of a lithium metal cathode. The method comprises the step of spraying a certain amount of treatment liquid on the surface of a lithium metal cathode or immersing the lithium metal cathode into the treatment liquid to obtain the lithium metal cathode with the self-adaptive elastic nano modification layer, wherein the treatment liquid comprises three parts of solute, solvent and additive, and the solute comprises one or more than one of polyester with polyether chain segments and carboxylic acid with reactive unsaturated groups. The lithium metal cathode obtained by the method is used for a lithium metal secondary battery, can greatly improve the safety performance and the cycle performance of the current battery, and has high practical value.

Description

Preparation method of metal lithium negative electrode self-adaptive elastic nano-modification layer

Technical Field

The invention relates to construction and application of an elastic nanometer modification layer of a lithium metal cathode.

Background

With the rapid development in the fields of electric vehicles, high-end consumer electronics, intelligent robots, unmanned aerial vehicles, aerospace, and the like, secondary batteries with higher energy density, higher power density, and longer life are urgently needed. At present, the traditional lithium ion battery taking graphite as a negative electrode material cannot meet the increasing energy storage requirement. Metallic lithium has a high specific capacity (3860mA h/g) and a lowest potential (-3.04Vs standard hydrogen electrode). Therefore, the lithium metal secondary battery using lithium metal as a negative electrode has characteristics of high operating voltage, large specific energy, and the like, and is the next-generation high specific energy density secondary battery having the most potential at present. But the commercial application of lithium metal is severely hindered by the side reaction of the lithium metal negative electrode with the electrolyte and the dendrite problem. On the one hand, the continuous growth of lithium dendrites may puncture the porous polymer separator to cause internal short circuits of the battery, resulting in safety problems; on the other hand, the growth of the lithium dendrite leads to the increase of the specific surface area of the metal lithium, the side reaction of the metal lithium and the electrolyte is increased, the depletion of the electrolyte and the large consumption of the metal lithium are caused, the uneven dissolution of the metal lithium dendrite generates 'dead lithium', the pulverization of a metal lithium negative electrode is caused, the interface resistance is increased, the combustion is easier, and the potential safety hazard is increased.

At present, researchers at home and abroad adopt schemes of negative electrode surface modification, electrolyte optimization, three-dimensional current collectors, diaphragm modification, solid electrolyte and the like to inhibit the growth of lithium dendrites, and certain achievements are achieved. However, these efforts have made it difficult to fundamentally solve the problems of the side reaction of the lithium metal negative electrode and the growth of dendrites. The solid electrolyte interface film (SEI) of a metallic lithium negative electrode plays a crucial role in the growth of lithium dendrites. The reaction of metallic lithium with an electrolyte forms an SEI film, which cannot withstand the volume change caused by the deposition of metallic lithium, thereby causing the breakage of the SEI film, causing the uneven deposition of metallic lithium, resulting in the nucleation and growth of lithium dendrites, and forming a new SEI film on the fresh surface of metallic lithium. During the stripping of metallic lithium, the SEI film breaks down and the uneven dissolution of lithium dendrites causes "dead lithium". The continuous breaking and generation of the SEI film in the process of depositing and stripping the metallic lithium result in a large number of side reactions, the acceleration of dendrite growth and the generation of dead lithium, which are significant challenges faced by the metallic lithium negative electrode. Therefore, an SEI film or a nano-modification layer which can automatically adapt to the volume change of the lithium metal and has a certain regulation effect on the uneven deposition of the lithium metal is one of the most ideal solutions for solving the lithium metal negative electrode.

The invention creatively adopts an in-situ reaction mode to construct a flexible and elastic nanometer modification layer on the metal lithium cathode, the nanometer modification layer can automatically adapt to the volume change of the deposition and stripping of the metal lithium, can automatically regulate and control the deposition and stripping of the metal lithium cathode, can effectively conduct lithium ions, reduce the generation of side reaction of the metal lithium and electrolyte, inhibit the growth of lithium dendrites, and greatly improve the safety of the metal lithium cathode.

Disclosure of Invention

The invention aims to provide a scheme of a lithium metal negative electrode self-adaptive elastic nanometer modification layer.

The invention provides a preparation technology of a metal lithium self-adaptive nanometer modification layer, which comprises the following steps: and spraying a certain amount of treatment solution on the surface of the metal lithium cathode or immersing the metal lithium cathode into the liquid, reacting for a period of time, and evaporating or volatilizing the treatment solution to obtain the metal lithium cathode with the self-adaptive nano modification layer.

In the preparation method, the treatment fluid comprises three parts of solute, solvent and additive. Wherein the solute is composed of one or more of polyesters having polyether segments and carboxylic acids having reactive unsaturated groups. The polyester having a polyether segment is preferably polyethylene glycol acrylate, polyethylene glycol diacrylate (PEGDA), polyethylene glycol methacrylate (PEGMA), and more preferably a combination of polyethylene glycol diacrylate (PEGDA) and polyethylene glycol methacrylate (PEGMA). The carboxylic acid with a reactive unsaturated group is selected from acrylic or methacrylic acid, butenedioic acid or dianhydride, preferably acrylic acid.

More preferably, the ratio of the polyester of the polyether segment, the carboxylic acid having a reactive unsaturated group, and the additive is about (1-5): (1-5): (0.1-5).

The solvent is dimethyl sulfoxide (DMSO), Tetrahydrofuran (THF), NMP (nitrogen methyl pyrrolidone), or the like, which is relatively stable in contact with lithium. The additive is one or more of nano silicon dioxide, lithium nitride, aluminum oxide and various metal lithium salts (such as lithium hexafluorophosphate, lithium borate and lithium bistrifluoromethanesulfonylimide), preferably lithium nitride, lithium hexafluorophosphate, lithium borate or lithium bistrifluoromethanesulfonylimide, and most preferably lithium nitride. Initiators such as Azobisisobutyronitrile (AIBN), dibenzoyl peroxide, and the like. Wherein the solute and the additive account for 0.05 per mill-25% of the total mass of the solution, and the mass ratio of the additive to the solute is 1: 50 to 1: 3.

in the preparation method, the mass fraction of the treatment liquid is 0.02 per thousand-10%, preferably 0.1 per thousand-2.5%, and the reaction time is 1s-10d, preferably 30s-10 h.

In the above preparation method, the reaction temperature is-20-100 deg.C, preferably 0-50 deg.C, and the volatilization or evaporation temperature of the solution is-20-200 deg.C, preferably-10-100 deg.C.

The lithium metal negative electrode of the present invention includes: pure metallic lithium, metallic lithium alloys such as: lithium boron alloys, lithium silicon alloys, lithium tin alloys, and the like, and lithium metal composites such as: a complex of metallic lithium with carbon, a complex of metallic lithium with copper, etc., a complex of a polymer with metallic lithium, etc.

When the lithium metal cathode is used in a lithium metal secondary battery, the cathode material can be an embedded compound cathode material (such as lithium cobaltate, lithium nickelate, lithium manganate, ternary material and lithium-rich material), an oxide material (such as manganese oxide, vanadium oxide, nickel oxide, cobalt oxide and the like), a sulfur cathode, an air cathode material and the like.

Compared with the prior art, the elastic nanometer modification layer on the surface of the lithium metal cathode has the following advantages: the surface nanometer modification layer has certain flexibility and elasticity, can be self-adapted to the volume change of the metal lithium cathode during deposition and stripping, regulates the uniformity of the deposition and stripping of the metal lithium and reduces the growth of lithium dendrites; the surface nanometer modification layer has stronger lithium ion conduction capability and can effectively conduct lithium ions; the electrolyte can stably exist on the surface of a metal lithium cathode, the electrolyte and the metal lithium are isolated, and the problems of side reaction of the electrolyte and the metal lithium and continuous breakage and self-repairing of an SEI film in the circulation process of the metal lithium battery are thoroughly solved; the thickness, composition and elasticity of the nanometer modification layer can be effectively regulated and controlled by regulating and controlling the components and reaction parameters of the treatment liquid. Therefore, the self-adaptive elastic nanometer modification layer can effectively reduce the growth of lithium dendrites and greatly improve the cycle performance and safety performance of the lithium metal cathode. The scheme is simple and feasible and is suitable for large-scale production.

Drawings

Fig. 1 is a stress-strain curve of the adaptive elastic nano-modification layer in example 1.

FIG. 2 shows Li/LiFePO for a common lithium metal anode in a comparative example₄SEM images after 20 cycles.

FIG. 3 shows Li/LiFePO of the lithium metal cathode with adaptive elastic nano-modification layer in example 1₄SEM images after 20 cycles.

Detailed Description

The present invention will be further described with reference to the following examples, but the present invention is not limited to the following examples.

The raw materials used in the following examples are commercially available unless otherwise specified.

Example 1 preparation of in-situ polymerization type composite modification layer on surface of lithium metal negative electrode

Under the atmosphere of high-purity argon, PEGDA700, PEGMA475, acrylic acid, nano lithium nitride (particles are 20nm) and azobisisobutyronitrile are polymerized according to the weight ratio of 1:1:1:0.1:0.02, then 0.2 wt% of DMSO treatment liquid is prepared to be dripped on the surface of metal lithium, the treatment liquid is dried in vacuum at 50 ℃ for two hours, and the metal lithium cathode with the elastic nano modification layer provided by the invention can be obtained.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic substances such as COR, COOR and the like and lithium nitride. The stress-strain curve of the gel state of the gel is tested by an Instron3365, and the breaking elongation of the gel can reach 630 percent.

Example 2 preparation of in-situ polymerization type composite modification layer on surface of lithium metal negative electrode

The other conditions were the same as in example 1 except that PEGDA400 and PEGMA200 were used instead of PEGDA700 and PEGMA475, respectively.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic substances such as COR, COOR and the like and lithium nitride. The stress-strain curve of the gel state of the gel is tested by an Instron3365, and the breaking elongation of the gel can reach 640 percent.

Example 3 preparation of in-situ polymerization type composite modification layer on surface of lithium metal negative electrode

The other conditions were the same as in example 1 except that PEGMA475 was not used and PEGDA700, acrylic acid, and nano lithium nitride (particles of 20nm) were polymerized in a weight ratio of 2:1: 0.1.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic substances such as COR, COOR and the like and lithium nitride. The stress-strain curve of the gel state of the gel is tested by an Instron3365, and the breaking elongation of the gel can reach 650 percent.

Example 4 preparation of in-situ polymerization type composite modification layer on surface of lithium metal negative electrode

The other conditions were the same as in example 1 except that PEGDA700 was not used and PEGMA475, acrylic acid, nano lithium nitride (particle 20nm) were polymerized in a weight ratio of 2:1: 0.1.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic substances such as COR, COOR and the like and lithium nitride. The stress-strain curve of the gel state of the gel is tested by an Instron3365, and the breaking elongation of the gel can reach 600 percent.

Example 5 preparation of in-situ polymerization type composite modification layer on surface of lithium metal negative electrode

The other conditions were the same as in example 1 except that lithium hexafluorophosphate was used in place of lithium nitride.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic matters such as COR, COOR and the like and lithium hexafluorophosphate. The stress-strain curve of the gel state of the gel is tested by an Instron3365, and the breaking elongation of the gel can reach 640 percent.

Example 6 preparation of in-situ polymerized composite modified layer on surface of lithium metal negative electrode

The other conditions were the same as in example 1 except that lithium borate was used instead of lithium nitride.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic matters such as COR, COOR and the like and lithium borate. The stress-strain curve of the gel state of the gel is tested by an Instron3365, and the elongation at break of the gel can reach 635%.

Example 7 preparation of composite lithium metal negative electrode surface Nano-modification layer

The other conditions were the same as in example 1 except that a complex of metallic lithium and carbon was first prepared by electrodeposition and a treatment liquid was dropped on the surface of the complex. The stress-strain curve in the gel state was tested with an Instron3365, which had an elongation at break of 630%.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic substances such as COR, COOR and the like and lithium nitride.

Example 8 preparation of composite lithium Metal Anode surface Nano-modification layer

The other conditions were the same as in example 1 except that a complex of metallic lithium and three-dimensional copper was first prepared by electrodeposition, and a treatment liquid was dropped on the surface of the complex.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic substances such as COR, COOR and the like and lithium nitride. The stress-strain curve in the gel state was tested with an Instron3365, which had an elongation at break of 630%.

Example 9

The other conditions were the same as in example 1 except that NMP was used instead of DMSO.

Comparative example 1, testing of a conventional lithium sheet.

To compare the electrochemical performance of lithium negative electrodes, polished lithium sheets were used as the samples of comparative example 1 (i.e., untreated lithium sheets in examples 1-11). And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains lithium oxide, lithium hydroxide, lithium carbonate and other components.

Comparative example 2 preparation of lithium phosphate modified layer on surface of lithium Metal

And treating the lithium sheet for 2min in a high-purity argon atmosphere by using DMSO (dimethyl sulfoxide) treatment liquid containing 0.01M polyphosphoric acid and 0.02% PVDF, and wiping off the redundant treatment liquid on the surface to obtain the lithium metal cathode containing the lithium phosphate SEI film.

And observing the morphology structure of the nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the film contains organic matters such as lithium phosphate, PVDF and the like. The stress-strain curve in the gel state was tested with an Instron3365, which had an elongation at break of 2%.

And (3) preparing an ex-situ lithium polyacrylate modification layer on the surface of the metal lithium.

And (3) dropwise coating a DMSO solution of 0.2% lithium polyacrylate on the surface of the metal lithium in a high-purity argon atmosphere, and evaporating the DMSO solution to dryness at 50 ℃ to obtain the metal lithium cathode containing ex-situ lithium polyacrylate modification.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic matters such as COR, COOR and the like. The stress-strain curve in the gel state was tested with an Instron3365, which had an elongation at break of 500%.

Comparative example 4 preparation of a composite modification layer of polymethyl methacrylate on the surface of lithium Metal

In a high-purity argon atmosphere, a DMSO solution of polymethyl methacrylate and polyethylene oxide (mass ratio of 1:2) with the mass fraction of 0.2% is dripped on the surface of the metal lithium, and the DMSO solution is evaporated to dryness at 50 ℃ to obtain the metal lithium cathode modified by the ex-situ polymethyl methacrylate and the polyethylene oxide.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic matters such as COR, COOR and the like. The stress-strain curve in the gel state was tested with an Instron3365, which had an elongation at break of 200%.

Comparative example 5 preparation of polyimide composite nanometer modification layer on surface of lithium metal cathode

And (2) in the atmosphere of high-purity argon, dropwise coating DMSO treatment liquid containing 0.2% of polyimide and 0.01% of lithium nitride (the particle size is 20nm) on the surface of the metal lithium, and performing vacuum treatment at 50 ℃ for two hours to dry the treatment liquid, so as to obtain the metal lithium cathode with the elastic nano modification layer.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic matters such as polyimide and the like and lithium nitride. The stress-strain curve of the gel state of the gel is tested by an Instron3365, and the breaking elongation of the gel can reach 120 percent.

Comparative example 6 preparation of polydimethylsiloxane-based composite modified layer on surface of lithium metal negative electrode

And (2) in the atmosphere of high-purity argon, dropwise coating DMSO treatment liquid containing 0.2% of polydimethylsiloxane and 0.01% of nano lithium nitride (the particle size is 20nm) on the surface of the metal lithium, and performing vacuum treatment at 50 ℃ for two hours to dry the treatment liquid, so that the metal lithium cathode with the elastic nano modification layer can be obtained.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic matters such as siloxane and the like and lithium nitride. The stress-strain curve of the gel state of the gel is tested by an Instron3365, and the breaking elongation of the gel can reach 270 percent.

Comparative example 7 preparation of lithium polyacrylate nanometer modification layer on surface of lithium metal cathode

The other conditions were the same as in example 1 except that the metallic lithium surface was treated with DMSO containing 0.2% polyacrylic acid by dropping on.

And observing the morphology structure of the elastic nanometer modification layer by using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). XPS shows that the surface of the material contains organic matters such as COR, COOR and the like. The stress-strain curve of the gel state of the gel is tested by an Instron3365, and the breaking elongation of the gel can reach 500 percent.

Comparative example 8 preparation of in-situ polymerization type composite modification layer on surface of lithium metal cathode

The other conditions were the same as in example 1 except that polyacrylic acid (40W) was used in place of acrylic acid.

TABLE 1 elongation at break of the polymers in the application examples and short-circuit time of the corresponding Li | Li symmetrical cells

And (3) disassembling all the lithium metal batteries in the application example after 20 cycles, and characterizing the morphology and the structure by using AFM and SEM. The surface of the lithium metal of comparative example 1 has a lot of moss-like dendrite structures as shown in fig. 2, while the surface of the lithium metal of examples 1 to 10 is relatively flat as shown in fig. 3. XPS characterization found that the metallic lithium surface in comparative example 1 had many metallic lithium reaction products with the electrolyte such as: lithium alkyl carbonate, lithium ethoxy, lithium fluoride, etc., while the main component of the surface of the lithium metal in the examples is the polymer component of the original nano-modification layer, the main component of the surface of the lithium metal in the example 1 is: COR, COOR, lithium nitride, and the like. Therefore, the surface composition and the morphological structure of the common metal lithium are greatly changed in the cycle process of the metal lithium battery, and the dendritic crystal continuously grows. The main components on the surface of the metal lithium cathode with the self-adaptive elastic nanometer modification layer are not obviously changed, the volume change caused by the deposition and dissolution of the metal lithium can be self-adapted, and the growth of lithium dendrites is effectively inhibited.

The test results of the Li | Li symmetric battery show that the metallic lithium negative electrode with the elastic adaptive nano-modification layer has longer short circuit time and better cycle life than the non-elastic modified metallic lithium negative electrode (such as the lithium phosphate metallic lithium negative electrode in comparative example 2) and the pure metallic lithium negative electrode (comparative example 1). The reaction of acrylic acid with carboxylic acid group and metallic lithium in the in-situ polymerization process can generate lithium polyacrylate capable of conducting lithium ions, and the process can greatly improve the binding capacity of the lithium polyacrylate and the metallic lithium cathode, so that the cycle life of the corresponding Li | Li symmetrical battery is far longer than that of the elastic nanometer modification layer of the ex-situ reaction (comparative example 3). From the comparison of examples 1-4, it can be seen that the copolymerization of acrylic acid and PEGDA, which is very flexible, is more flexible and the cycle life of the cell is higher; it was found that the combination of two PEGDA's with acrylic acid polymerized in situ was more effective than one, with the polymer chain segments being slightly longer than the cycle life of some cells. This may be due to the different ability of the hinge to conduct lithium ions due to the different interpenetrating network structures formed. From the comparison of examples 1, 5, 6, it was found that the doping of the inorganic particulate lithium nitride works best. From the comparison of example 1 with comparative examples 7 and 8, it was found that copolymerization using acrylic acid is more effective and the cycle life of the battery is longer than the treatment using polyacrylic acid (40W) alone or copolymerization using polyacrylic acid. Since the lithium ion conductivity of the lithium polyacrylate composite is far greater than that of PDMS (comparative example 5) and polyimide (comparative example 6), and the elasticity of the lithium polyacrylate composite is better than that of the polymethyl methacrylate composite (comparative example 4), the symmetric metal lithium battery with the elastic nano-modification layer of the lithium polyacrylate composite has a better cycle life. From the comparison between example 1 and comparative examples 8 and 9, it can be seen that the particle size of lithium nitride, the drying temperature of the solution, etc. also have some influence on the nano-modification layer. It can be seen from examples 8 and 9 that this treatment technique, in combination with a nanocomposite lithium metal negative electrode, greatly improves the cycle life of a lithium metal symmetric battery.

In summary, the invention constructs an elastic nanometer modification layer on the surface of the metal lithium negative electrode or the nanometer composite metal lithium negative electrode. The nanometer modification layer can effectively prevent the reaction of the lithium metal and the electrolyte, inhibit the formation of lithium dendrites and prolong the cycle life of the lithium metal cathode. The method has the advantages of simple preparation, cheap and easily-obtained raw materials, suitability for large-scale production and good application prospect.

The above-mentioned embodiments are only preferred embodiments of the present invention, and are not intended to limit the embodiments of the present invention, and those skilled in the art can easily make various changes or modifications according to the main concept and spirit of the present invention, so the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A preparation method of a metal lithium negative electrode self-adaptive elastic nanometer modification layer comprises the following steps: under inert atmosphere, spraying a certain amount of treating fluid on the surface of the metal lithium cathode or immersing the metal lithium cathode into the treating fluid, reacting for a period of time, evaporating or volatilizing the treating fluid to obtain the metal lithium cathode with the self-adaptive elastic nanometer modification layer, and is characterized in that: the treatment fluid comprises three parts of solute, solvent and additive, wherein the solute is composed of more than one of polyester with polyether chain segments and carboxylic acid with reactive unsaturated groups;

the polyester with polyether segments is a combination of polyethylene glycol diacrylate (PEGDA) and polyethylene glycol methacrylate (PEGMA);

the carboxylic acid with a reactive unsaturated group is selected from acrylic acid or methacrylic acid;

the additive is selected from lithium nitride;

the proportion of the polyester of the polyether chain segment, the carboxylic acid with the reactive unsaturated group and the additive is (1-5): (1-5): (0.1-5).

2. The method of claim 1, wherein the solvent is selected from the group consisting of dimethyl sulfoxide (DMSO), Tetrahydrofuran (THF), and N-methylpyrrolidone (NMP) that are relatively stable in contact with lithium.

3. The method of claim 1 wherein the inert atmosphere comprises one or more of argon, helium, and neon.

4. The method according to claim 1, wherein the mass fraction of the solute in the treatment solution is 0.02 per mill to 20%, and the reaction time is 1s to 10 d; the content of the additive in the treatment fluid is 0.01 per mill-5%, and the thickness of the self-adaptive nanometer modification layer is 1-2000 nm finally by regulating and controlling the concentration and the dosage.

5. The method according to claim 4, wherein the mass fraction of solute in the treatment fluid is 0.1-10%; the reaction time is 30s-10 h; the content of the additive is 0.05 per mill-2%; the thickness of the self-adaptive nanometer modification layer is 5-200 nm.

6. The method of claim 1, wherein the reaction temperature is-20-100 ℃ and the temperature for volatilizing or evaporating the solution is-20-200 ℃.

7. The method of claim 6, wherein the reaction temperature is-10-50 ℃ and the volatilization or evaporation temperature of the solution is-10-100 ℃.

8. The method of claim 1, the lithium metal anode comprising: pure metallic lithium or metallic lithium alloys.

9. A metal lithium secondary battery is composed of a negative electrode material, a diaphragm, an electrolyte and a positive electrode material, wherein the positive electrode material is selected from an embedded compound positive electrode material, an oxide positive electrode material, a sulfur positive electrode and an air positive electrode material; the negative electrode material is a lithium negative electrode with a self-adaptive nanometer modification layer obtained by the method of any one of claims 1 to 8; the diaphragm comprises a PP film, a PE film, a PP/PE/PP film, a cellulose film or a glass fiber film.

10. An energy storage element, characterized by: the energy storage element contains the lithium metal secondary battery according to claim 9.