CN114976038B

CN114976038B - Silver-silver oxide heterogeneous nanoflower modified foamy copper and preparation method and application thereof

Info

Publication number: CN114976038B
Application number: CN202210900959.5A
Authority: CN
Inventors: 谢佳; 覃明盛; 吴强
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2022-07-28
Filing date: 2022-07-28
Publication date: 2022-10-25
Anticipated expiration: 2042-07-28
Also published as: CN114976038A

Abstract

The invention provides silver-silver oxide heterogeneous nanoflower modified foamy copper and a preparation method and application thereof. The preparation process of the silver-silver oxide heterogeneous nanoflower modified foamy copper comprises the following steps: and cleaning the surface of the foam copper, adopting concentrated nitric acid and hydrogen peroxide for synergistic treatment, then placing the foam copper in a silver nitrate solution containing sodium dodecyl sulfate for reaction, and then carrying out subsequent cleaning and drying to obtain the silver-silver oxide heterogeneous nano flower structure growing in situ. The composite lithium metal cathode formed by modifying the foam copper with the prepared silver-silver oxide heterogeneous nanoflower has more excellent electrochemical performance and has the potential of large-scale application.

Description

Silver-silver oxide heterogeneous nanoflower modified foamy copper and preparation method and application thereof

Technical Field

The invention relates to the technical field of lithium batteries, in particular to a silver-silver oxide heterogeneous nano flower modified copper foam material and a preparation method and application thereof.

Background

Lithium dendrites are dendritic metallic lithium formed when lithium ions are reduced during charging of a lithium battery. Lithium dendrite growth affects the coulombic efficiency and cycle number of the battery. At present, the developed high lithium-philic metal modification material is considered to inhibit lithium dendrites to some extent and improve the performance of the lithium metal negative electrode.

For example, patent document CN110061191B discloses a three-dimensional lithium metal negative electrode, and a preparation method and application thereof, specifically, a three-dimensional copper foam is immersed in NaOH solution and (NH) ₄ ) ₂ S ₂ O ₈ For a certain time to form C in 3Du(OH) ₂ The nanowire structure and the result show that the three-dimensional lithium metal cathode also relieves the huge volume expansion of the lithium metal cathode, solves the problem of dendritic lithium formation, and realizes the high rate performance and long cycle life of the lithium metal battery. However, the three-dimensional foam copper H modified by the metal nano material can be obtained only by reducing the copper H in the atmosphere at 250-300 DEG C ₂ High temperature reduction danger, high cost and no contribution to large-scale application.

For another example, patent document CN109088051a discloses a high-safety metallic lithium negative electrode without surface dendrite, and a preparation method and application thereof, which discloses lithium-philic metallic materials including, but not limited to, gold, silver, and zinc. A method of making a lithium metal anode, comprising: s1, sputtering a lithium-philic material on a three-dimensional porous matrix: commercial foam copper is rolled by 50% strain by using a roller press, then ultrasonically cleaned in dilute hydrochloric acid, deionized water and absolute ethyl alcohol in sequence, then dried in vacuum, and a lithium-philic material is sputtered and deposited on the foam copper material treated by hydrochloric acid by using a magnetron sputtering method; and S2, depositing the material prepared in the step S1 and a metal lithium counter electrode by adopting an electrochemical deposition method to obtain a metal lithium cathode from the material prepared in the step S1 or pouring molten metal lithium into the material prepared in the step S1 to obtain the metal lithium cathode. However, magnetron sputtering requires special equipment and is complicated to operate, and is difficult to apply in batches. In addition, the lithium-philic material obtained by magnetron sputtering is modified, lacks the formation of chemical bonds, belongs to physical contact, has poor structural stability, and is difficult to ensure that the lithium-philic material stably exists on a three-dimensional current collector for a long time.

Disclosure of Invention

Based on the above, there is a need to develop a simple silver-silver oxide heterogeneous nanoflower modified copper foam material which is easy to batch, and a preparation method and application thereof, and when the silver-silver oxide heterogeneous nanoflower modified copper foam material is applied to a lithium metal battery, the coulomb efficiency and the cycling stability of the metal battery can be further improved.

The invention adopts the following technical scheme:

the invention provides silver-silver oxide heterogeneous nanoflower modified foamy copper and a preparation method thereof, wherein the preparation method comprises the following steps: obtaining a cleaned foamed copper material; placing the copper foam into an aqueous solution containing hydrogen peroxide and nitric acid for reaction to obtain acid oxygen treatment foam copper; and (3) placing the acid oxygen treated foamy copper in a silver nitrate solution containing sodium dodecyl sulfate, reacting, cleaning a product, and drying to obtain the foamy copper material with a silver-silver oxide heterogeneous nano flower structure.

In some embodiments, the silver nitrate solution has a concentration of 0.01 to 0.1m (preferably 0.05M), the sodium dodecyl sulfate has a content of 0.01 to 0.5wt% (preferably 0.1 wt%), and the solvent is a mixture of 1 to 5 (preferably 1 to 2 to 3) by volume of ethylene glycol and water for a reaction time of 1 to 30min (preferably 4 to 8 min).

In some embodiments, the volume percentage of the hydrogen peroxide is 1 to 10% (preferably 2 wt%), the volume percentage of the concentrated nitric acid is 1 to 10% (preferably 5 wt%), and the reaction time is 1 to 30min (preferably 4 to 6 min).

In some of these embodiments, the drying is vacuum drying at 50 to 150 ℃.

The invention also provides a lithium metal composite cathode, which is prepared by depositing lithium metal on the silver-silver oxide heterogeneous nano flower modified foam copper material by adopting an electrochemical deposition method. Preferably, the electrochemical deposition process comprises the following steps: assembling silver-silver oxide heterogeneous nanoflower modified foam copper and metal lithium into a button type half battery in a glove box, adopting a PP diaphragm, dropwise adding electrolyte, and controlling the concentration of 0.1-10 mA cm ^-2 Quantitative current density deposition (0.1 to 10 mAhcm) ^-2 ) On the lithium metal composite anode. Preferably, the current density is 0.5 to 5 mAcm ^-2 The deposition amount is 0.5 to 5 mAhcm ^-2 。

The present invention can also provide a lithium metal battery comprising the above lithium metal composite negative electrode.

Compared with the prior art, the invention has the beneficial effects that:

compared with the modified foam copper material subjected to alkaline etching treatment, the modified foam copper material provided by the invention has the advantages that the silver-silver oxide heterogeneous nano flower modified foam copper material is provided for the first time, the nano flowers are uniformly distributed, and the modified foam copper material has more excellent coulombic efficiency and cycle performance when being applied to a lithium metal battery.

Drawings

FIG. 1 is an SEM photograph of the reaction product of step S2 in example 1; wherein, the graph a corresponds to a test graph of a product only treated by a hydrogen peroxide aqueous solution, and the graph b corresponds to a test graph of a product only treated by a nitric acid aqueous solution; the c diagram corresponds to the test diagram of the product treated with hydrogen peroxide and concentrated nitric acid simultaneously.

Fig. 2 is an optical photograph and XRD pattern of the silver-silver oxide heterogeneous nano flower-modified copper foam and the original copper foam of example 1.

FIG. 3 is a scanning electron micrograph of the silver-silver oxide heterogeneous nanoflower modified foamy copper and the original foamy copper of example 1. Wherein, the drawing a is an SEM (scanning electron microscope) drawing of original copper foam, the drawing b is the copper foam modified by silver nitrate aqueous solution containing sodium dodecyl sulfate, and the drawing c is the drawing which singly adopts 0.05mol/L silver nitrate mixed solution without 0.1 percent of sodium dodecyl sulfate.

FIG. 4 is a scanning electron microscope image of silver-silver oxide heterogeneous nanoflower modified foamy copper obtained by performing a replacement reaction with an aqueous solution alone in example 1.

Fig. 5 is a graph of coulombic efficiencies of the copper foam decorated with silver-silver heterogeneous nanoflowers and the original copper foam in example 1.

Fig. 6 is a lithium deposition graph of modified copper foam and original copper foam using silver-silver oxide heterogeneous nanoflowers in example 1.

FIG. 7 is a 1mAhcm deposit of silver-silver oxide heterogeneous nanoflower modified foamy copper and original foamy copper of example 1 ^-2 Scanning electron micrographs of lithium metal.

FIG. 8 is a scanning electron microscope image of silver-silver oxide heterogeneous nano-flower modified foamy copper obtained by different silver nitrate concentrations.

FIG. 9 is a scanning electron microscope image of three-dimensional foamy copper obtained after etching with concentrated hydrochloric acid.

Detailed Description

The present invention is further described in detail below with reference to specific examples so that those skilled in the art can more clearly understand the present invention.

The following examples are provided only for illustrating the present invention and are not intended to limit the scope of the present invention. All other embodiments obtained by a person skilled in the art based on the specific embodiments of the present invention without any inventive step are within the scope of the present invention.

In the examples of the present invention, all the raw material components are commercially available products well known to those skilled in the art unless otherwise specified; in the examples of the present invention, unless otherwise specified, all the technical means used are conventional means well known to those skilled in the art.

Test example 1

The test example provides a method for modifying copper foam by silver-silver oxide, which comprises the following steps:

s1, cutting a three-dimensional foam copper material with the thickness of 0.2 mm into pole pieces with the diameter of 10 mm, and placing the pole pieces in a mixed solution (100 mL) of water and absolute ethyl alcohol with the volume ratio of 1:1 for ultrasonic treatment for 5min.

And S2, placing the foamed copper washed in the step S1 into a mixed aqueous solution containing 2% hydrogen peroxide and 5% concentrated nitric acid in percentage by volume, and stirring for reaction for 5min to obtain the acid oxidation-treated foamed copper.

And S3, transferring the acid oxidation treatment foamy copper prepared in the step S2 into 0.05mol/L silver nitrate mixed solution (the solvent is ethylene glycol and water with the volume ratio of 1:2) containing 0.1% of sodium dodecyl sulfate, and stirring for reacting for 5min to obtain a silver-silver oxide modified foamy copper crude product.

And S4, washing the reaction product obtained in the step S3 by using an ethanol water solution to prepare a silver-silver oxide modified foamy copper crude product, and placing the foamy copper crude product at 100 ℃ for vacuum drying for 5 hours to obtain the silver-silver oxide modified foamy copper.

In this test example, a control test in which an aqueous solution of 2% by volume of hydrogen peroxide or an aqueous solution of 5% by volume of concentrated nitric acid was used alone was simultaneously studied, and SEM test was performed on the copper foam subjected to acid oxidation treatment, and the results are shown in fig. 1.

Compared with the a diagram (the product treated by only the aqueous solution of hydrogen peroxide) and the b diagram (the product treated by only the aqueous solution of silver nitrate) of the graph in fig. 1, the surface structure of the copper foam treated by the synergistic treatment of the mixed aqueous solution of hydrogen peroxide and silver nitrate has more micropores and more defect structures.

As shown in the photo results of fig. 2, the final product of the foam copper modified with the silver nitrate aqueous solution containing sodium dodecyl sulfate shows color change and silver gray compared with the original three-dimensional foam copper material. Meanwhile, an XRD test chart can show that the final product has a silver oxide peak, and the generation of a silver oxide heterostructure in the final product is proved.

As shown in fig. 3, the final silver oxide modified copper foam material was photographed optically in comparison with the original three-dimensional copper foam material (a in fig. 3) and the product (c in fig. 3) treated with 0.05mol/L silver nitrate mixed solution (ethylene glycol to water volume ratio 1:2) without 0.1% sodium dodecylsulfate alone. Compared with the structures of the graph a and the graph c in the figure 3, the copper foam reaction product modified by the silver nitrate aqueous solution containing sodium dodecyl sulfate in the graph b has a nanoflower heterostructure, and is uniformly dispersed and uniform in size.

In addition, it should be noted that, simply using ethylene glycol as a solvent, the solubility of silver nitrate and sodium dodecyl sulfate is very limited, and experiments are difficult to develop. After the mixed solution of the ethylene glycol and the water is adopted, a large amount of silver nitrate and sodium dodecyl sulfate can be dissolved, and the experiment can be carried out. In a pure water system, silver nitrate and foam copper have a displacement reaction which is very quick, and deposited silver is not uniform and is easy to cluster and presents as agglomerated nano particles. As shown in fig. 4, in the synergistic mixed system of ethylene glycol and water, the overall reaction rate is relatively proper and the surface morphology is optimal.

Compared with the original three-dimensional copper foam, the silver-silver oxide modified copper foam prepared in the embodiment is further punched into a proper size, a metal lithium sheet is used as a counter electrode, and the current density is 1mA cm ^-2 Depositing for 1h, and electrodepositing to obtain the surface capacity of 1mAh cm ^-2 The composite lithium metal electrode is subjected to a coulombic efficiency test to obtain a coulombic efficiency data map (figure 5), and a data map of metal lithium deposition is further obtained (figure 6). The results show that: the copper foam modified by silver oxide has higher coulombic efficiency, metal lithium is uniformly deposited, meanwhile, the copper foam modified by silver oxide has lower deposition overpotential, and the deposition dynamics is more excellent.

Further, scanning electron microscope tests were performed on the composite lithium metal electrode prepared by electrodeposition, and the results are shown in fig. 7, in which the silver-silver oxide-modified copper foam deposited lithium was more dense and had a relatively smooth and flat surface.

And further assembling a composite lithium metal cathode prepared by electrodeposition for 1h and a commercial lithium iron phosphate positive plate into a battery, and carrying out rate and cycle performance tests: the composite lithium metal cathode and the lithium iron phosphate are respectively used as a negative electrode and a positive electrode, and the electrolyte is 1M LiPF ₆ Dissolved in DME/DOL (1 vol%) and 3wt% lithium nitrate was added, the test voltage was between 3 and 3.9V, and 1C was defined as 170 mAhg-1. The results are shown in the following table:

table 1 rate performance and cycle performance of composite lithium metal negative electrode and commercial lithium iron phosphate full cell

Test example 2

The test example explores the influence of silver nitrate solutions (0.01M, 0.05M, 0.08M, 0.1M) containing 0.1% sodium dodecyl sulfate in different concentrations on the performance of modified foam copper composite lithium metal negative electrodes. The results are shown in the following table:

TABLE 2 Li/Cu @ Ag-Ag of composite lithium metal negative electrode obtained from different silver nitrate solutions ₂ Coulombic efficiency and cyclic stability of O

It is worth to be noted that when the silver nitrate concentration is too low, the area of the prepared nano silver-silver oxide modified on the surface of the foam copper is small, and the nano silver-silver oxide is scattered on the surface of the foam copper in a sporadic manner, as shown in a in fig. 8, the lithium affinity is not obviously improved, and the electrochemical performance is not excellent enough. When the concentration of silver nitrate is too high, the displacement reaction is excessively performed, so that the nano silver-silver oxide cluster on the surface of the copper foam is accumulated, the structure is loose and not compact, and the stability is poor, as shown in b in fig. 8.

Test example 3

The experimental example provides a method for modifying copper foam with silver oxide, and the preparation process steps are the same as those in example 1, except that: the treatment liquid in the step S3 is 0.05mol/L silver nitrate water solution containing 0.01 percent of sodium dodecyl sulfate.

In addition, it is worth to say that, the content of the surfactant is higher than 0.5wt% in the experiment, so that the nano silver modified foamy copper which tends to generate nano particles and is deposited on the surface is obtained, and the surface of the subsequent surfactant residual foamy copper is difficult to clean, so that the electrochemical performance is influenced. The content of the surfactant is too low (less than 0.01 wt%), the nano silver is easy to agglomerate, and the reaction is not uniform.

Test example 4

The experimental example provides a method for modifying copper foam with silver oxide, and the preparation process steps are the same as those in example 1, except that: and stirring and reacting for 30min in the step S3.

Comparative example 1

The comparative example provides a method for modifying foam copper by silver, the preparation process steps are the same as those of the experimental example 1, and the difference is only that: in step S2, only an aqueous solution of concentrated nitric acid of 5% by volume is used.

Comparative example 2

The comparative example provides a method for modifying foam copper by silver, the preparation process steps are the same as those of the experimental example 1, and the difference is only that: in the step S2, only aqueous solution with 2 percent of hydrogen peroxide by volume is adopted for surface reaction treatment.

Comparative example 3

The comparative example provides a method for modifying foam copper by silver, the preparation process steps are the same as those of the experimental example 1, and the difference is only that: the treatment liquid in the step S3 does not contain sodium dodecyl sulfate and is only 0.05mol/L silver nitrate water solution.

Comparative example 4

This comparative example provides a method of silver-modified copper foam, which has the same process steps as example 1, except that: in step S2, only concentrated hydrochloric acid with a volume percentage of 5% is used for the surface reaction treatment.

The structure of the prepared silver modified foamy copper is shown in figure 9, the concentrated hydrochloric acid reacts very violently, the structure of the obtained modified foamy copper is damaged, and the subsequent electrochemical performance is influenced by the residual chloride ions.

Comparative example 5

This comparative example provides a method of silver-modified copper foam, which has the same process steps as example 1, except that: in step S2, only 0.5M aqueous sodium hydroxide solution was used for the surface reaction treatment.

Comparative example 6

The comparative example provides a method for modifying foam copper by zinc, and the preparation process steps are the same as those of the example 1, and the difference is only that: the silver nitrate in step S3 is changed to zinc nitrate.

In addition, the method is also based on the technical scheme of patent document CN109088051A, wherein gold is expensive and has no possibility of practical application. The lithium affinity of zinc is largely confirmed to be inferior to that of silver, and the electrochemical performance is inferior. Therefore, the scheme of patent document CN109088051a in example 5 is selected for comparison with the scheme of patent example 1. It was found that the coulomb efficiency obtained in this example 1 is higher and the performance is more beneficial. In addition, the method has the advantages of lower cost and simpler operation.

Comparative example 7

By adopting the technical scheme of patent document CN110061191B, experiments are carried out according to the steps of example 1 in the patent document, and the three-dimensional lithium metal negative electrode is prepared.

The test statistics are respectively carried out on the silver-silver oxide modified foamy copper prepared by the test example and the composite metal lithium cathode, the silver-silver oxide modified foamy copper is prepared by adopting the steps S1-S4 in the test example 1, the test example 2 adopts a test sample obtained by 0.01M silver nitrate, the test example 3 adopts a test sample obtained by 0.05mol/L silver nitrate aqueous solution containing 0.01% sodium dodecyl sulfate, and the test example 4 only changes the test sample obtained by stirring for 30min in the step S3. The test method is as follows: in testing the average coulombic efficiency and the deposition overpotential, the button cell was assembled using a silver-silver oxide modified metal current collector and 200 μm lithium foil with a deposited current density of 1mAcm ^-2 The deposited capacity is 1mAhcm ^-2 Then, the voltage was charged to 1V to complete the lithium exfoliation. The unlined coulombic efficiency was obtained by dividing the stripped lithium content by the deposited lithium content.

In the test of the lithium iron phosphate/Li full battery, a composite lithium metal negative electrode and lithium iron phosphate are respectively used as a negative electrode and a positive electrode, and an electrolyte solution is 1M LiPF ₆ Dissolved in DME/DOL (1 vol%) and 3wt% lithium nitrate was added, the test voltage was 3 to 3.9V, and 1C was defined as 170 mAhg ^-1 。

The results are shown in the following table:

further, a large number of experimental researches are carried out in the application, and the results show that:

(1) When the volume percentage of the hydrogen peroxide in the preparation process is 1 to 10 percent (preferably 2 percent), the volume percentage of the concentrated nitric acid is 1 to 10 percent (preferably 5 percent), and the acid oxygen treatment foamy copper obtained in the reaction for 1 to 30min has the finest surface structure and contains a proper amount of surface defects, so that the subsequent replacement reaction is facilitated, and the three-dimensional structure of the foamy copper is not damaged. When the concentration of hydrogen peroxide and nitric acid is too low, the surface of the copper foam is not sufficiently activated, on one hand, the oil and the oxide layer on the surface are difficult to remove, and on the other hand, enough active sites are difficult to create on the surface of the copper foam for subsequent reaction, so that the modification efficiency of the nano silver-silver oxide is not high, the deposition of the nano silver-silver oxide is not uniform, the copper foam is seriously etched due to too high concentration, the three-dimensional structure is damaged, and the stability of the structure is not facilitated.

(2) Placing the acid oxygen treatment foamy copper into 0.05M silver nitrate solution containing 0.1wt% of sodium dodecyl sulfate, reacting for 1-30min, wherein the volume ratio of ethylene glycol to water is 1. The obtained composite lithium metal negative electrode has the best performance.

When the concentration of silver nitrate is too high, the nano silver-silver oxide is easy to agglomerate on the surface of the third copper foam, and the deposited nano silver is thicker and has poor structural stability. The low concentration of silver nitrate can cause that the deposited nano silver can not cover the surface of the foam copper to the maximum extent, and the lithium affinity improving effect is poor.

The sodium dodecyl sulfate concentration is too low, so that the nano silver-silver oxide is not uniformly dispersed, and the excessive content of the sodium dodecyl sulfate can cause the nano silver-silver oxide to be converted into particles to be agglomerated on the surface of the copper foam, and the residual surfactant is difficult to clean so as to influence the subsequent electrochemical performance.

The single ethylene glycol solution is difficult to carry out reaction, and the single aqueous solution causes the reaction speed to be too fast and the nano silver deposition to be not uniform enough. The best deposition results are obtained only when glycol and water are mixed.

(3) When the treatment solution in the process step S2 is replaced with strong alkali or hydrochloric acid, a copper hydroxide byproduct is easily generated on the surface of the copper foam under an alkaline condition, and the byproduct is coated on the surface of the copper foam, so that on one hand, the occurrence of a subsequent silver nitrate replacement reaction is prevented, and the uniformity and efficiency of the reaction are reduced, and on the other hand, the copper hydroxide byproduct is easily converted into low-electron-conductivity products such as copper oxide and the like in a subsequent process, and the electrochemical performance is finally affected.

In the case of hydrochloric acid treatment, impurities containing chloride ions are likely to remain on the surface of the copper foam, and electrochemical performance is affected. In addition, the etching uniformity of the hydrochloric acid is not as uniform as that of the nitric acid and the hydrogen peroxide.

(4) The nano flower structure of the heterogeneous silver-silver oxide is formed by stacking ultrathin nano sheets, the thickness of each nano sheet is 10-100 nm, the length of each nano sheet is 200-800 nm, and the nano sheets are formed by arranging countless nano particles in parallel. The nano sheets are uniformly covered on the surface of the foam copper, and slightly aggregated at the edge part of the foam copper.

It should be noted that the above examples are only for further illustration and description of the technical solution of the present invention, and are not intended to further limit the technical solution of the present invention, and the method of the present invention is only a preferred embodiment, and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of silver-silver oxide heterogeneous nanoflower modified foamy copper is characterized by comprising the following steps:

s1, obtaining a cleaned foamed copper material;

s2, placing the copper foam into an aqueous solution containing hydrogen peroxide and nitric acid, and reacting to obtain acid-oxygen treated copper foam;

and S3, placing the acid oxygen treatment foamy copper into a silver nitrate solution containing sodium dodecyl sulfate, wherein the concentration of the silver nitrate solution is 0.01-0.1M, the content of the sodium dodecyl sulfate is 0.01-0.5 wt%, the solvent adopts ethylene glycol and water in a volume ratio of 1 to 1-5, reacting, cleaning and drying a product, and obtaining the foamy copper material with a silver oxide heterogeneous nano flower structure.

2. The method for preparing silver-silver oxide heterogeneous nanoflower modified foamy copper according to claim 1, wherein the reaction time in the step S3 is 1-30min.

3. The method for preparing silver-silver oxide heterogeneous nanoflower modified foamy copper according to claim 2, wherein in the step S3, the concentration of the silver nitrate solution is 0.05M, the content of the sodium dodecyl sulfate is 0.1wt%, the solvent is ethanol and water in a volume ratio of 1.

4. The method for preparing silver-silver oxide heterogeneous nanoflower modified foamy copper according to any one of claims 1 to 3, wherein in the step S2, the hydrogen peroxide is contained in a volume percentage of 1 to 10%, the nitric acid is contained in a volume percentage of 1 to 10%, and the reaction time is 1 to 30min.

5. The method for preparing silver-silver oxide heterogeneous nanoflower modified foamy copper according to claim 4, wherein in the step S2, the volume percentage of hydrogen peroxide is 2%, the volume percentage of nitric acid is 5%, and the reaction time is 4-6 min.

6. The method for preparing silver-silver oxide heterogeneous nanoflower modified foam copper according to any one of claims 1 to 3, wherein the drying is vacuum drying at 50 to 150 ℃.

7. A lithium metal composite negative electrode is characterized in that lithium metal is prepared by depositing lithium metal on the silver-silver oxide heterogeneous nano flower modified foam copper material prepared according to any one of claims 1 to 6 by adopting an electrochemical deposition method.

8. The lithium metal composite anode according to claim 7, wherein the electrochemical deposition comprises the following steps: assembling silver-silver oxide heterogeneous nanoflower modified foam copper and metal lithium into a button type half battery, adopting a PP diaphragm, dropwise adding electrolyte, and controlling the concentration of the electrolyte to be 0.1-10 mA cm ^-2 And depositing metal lithium at the current density to obtain the lithium ion battery.

9. A lithium metal battery comprising the lithium metal composite negative electrode according to claim 7 or 8.