Lithium metal negative electrode composite current collector and preparation method thereof, lithium ion battery

Abstract

The application belongs to the technical field of batteries, and particularly relates to a lithium metal negative electrode composite current collector, which comprises a metal base layer and a transition metal boride layer arranged on at least one surface of the metal base layer. The lithium metal negative electrode composite current collector can effectively improve the wettability and bonding force of the negative electrode lithium metal layer and the current collector through the transition metal boride layer, can form an atomic-scale lattice match with lithium metal, can guide the uniform deposition of lithium metal atoms on the surface of the current collector, can inhibit the growth of lithium dendrites, and can effectively improve the safety and stability of the battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a lithium metal negative electrode composite current collector and a preparation method of the lithium metal negative electrode composite current collector and a lithium ion battery. BACKGROUND

[0002] With the development of science and technology and the improvement of people's living standards, there is a higher requirement for the energy density of batteries of portable electronic devices and electric vehicles. At present, the negative electrode material of commercialized lithium ion batteries is generally graphite-based material, and the theoretical capacity is limited (372 mAh / g), which is difficult to meet the development needs of high-performance lithium ion batteries. Therefore, developing a new type of negative electrode material with high capacity has become an important research direction of lithium ion batteries. Lithium metal negative electrode has extremely high specific capacity (3860 mAh / g) and extremely low redox potential (-3.045 V vs SHE), and is extremely promising as a high-capacity negative electrode material. However, during the cycle process of lithium metal, non-uniform deposition of lithium atoms on the surface of the current collector is easy to generate lithium dendrites, which not only leads to rapid reduction of the performance of the battery and shortens the service life of the battery, but also generates lithium dendrites to pierce the separator and cause safety problems such as short circuit of the battery.

[0003] In order to solve the problem that lithium metal negative electrode is easy to generate lithium dendrites on the surface of the current collector, researchers have proposed different strategies to inhibit lithium dendrites. In some prior art, a layered composite material of lithium is disclosed, which uniformly distributes a composite additive on the surface of a lithium metal sheet, and presses the composite additive into the lithium metal sheet by using a rolling method, folds the composite of the composite additive and the lithium metal sheet, rolls, and obtains an additive-lithium metal composite sheet with a layered structure. In some other prior art, a double-layer structure composite negative electrode of lithium / modified graphene layer is disclosed, which is attached to the lithium metal sheet by modifying the graphene. However, there is still a key technical problem of poor wettability and low bonding force between the lithium metal and the current collector material. SUMMARY

[0004] The purpose of the present application is to provide a lithium metal negative electrode composite current collector and a preparation method thereof, which aims to solve the problem that the existing lithium metal negative electrode is easy to form lithium dendrites on the surface of the current collector, and has poor wettability and low bonding force with the current collector material to some extent.

[0005] To achieve the above-mentioned application purposes, the technical solutions adopted by the present application are as follows:

[0006] In a first aspect, the present application provides a lithium metal negative electrode composite current collector, comprising: a metal substrate layer and at least a transition metal boride layer arranged on one surface of the metal substrate layer.

[0007] In a second aspect, the present application provides a preparation method of a lithium metal negative electrode composite current collector, comprising the following steps:

[0008] obtaining a metal substrate layer, forming a transition metal boride layer on at least one surface of the metal substrate layer, to obtain a lithium metal negative electrode composite current collector.

[0009] In a third aspect, the application provides a lithium ion battery, comprising a lithium metal negative electrode, wherein the lithium metal negative electrode comprises a lithium metal layer and a composite current collector arranged on one surface of the lithium metal layer, and the composite current collector comprises a metal substrate layer and a transition metal boride layer arranged between the metal substrate layer and the lithium metal layer.

[0010] The lithium metal negative electrode composite current collector provided by the first aspect of the application can effectively improve the wettability and bonding force of the negative electrode lithium metal layer and the current collector through the transition metal boride layer, and can form atomic-scale lattice matching with lithium metal, thereby guiding the uniform deposition of lithium metal atoms on the surface of the current collector and inhibiting the growth of lithium dendrites, and effectively improving the safety and stability of the battery.

[0011] The preparation method of the lithium metal negative electrode composite current collector provided by the second aspect of the application can obtain the lithium metal negative electrode composite current collector after forming the transition metal boride layer on at least one surface of the metal substrate layer, and the preparation method is simple and suitable for industrial large-scale production and application.

[0012] The lithium ion battery provided by the third aspect of the application uses the above-mentioned composite current collector as the negative electrode current collector, and the transition metal boride layer is arranged between the lithium metal layer and the metal substrate layer, so that the lithium metal layer and the composite current collector layer are combined closely, and the transition metal boride layer can form atomic-scale lattice matching with lithium, which can effectively inhibit the growth of lithium dendrites. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0014] Figure 1 is a structural schematic diagram of the lithium metal negative electrode composite current collector provided by the embodiments of the application;

[0015] Figure 2 is an X-ray diffraction pattern of the composite current collector provided by Embodiment 1 of the application;

[0016] Figure 3 is a morphology diagram of the current collector after depositing the lithium metal layer provided by Embodiment 1 and Comparative Example 1 of the application.

[0017] Figure 4is a morphology diagram of the current collector provided by Embodiment 1 and Comparative Example 1 of the present application after lithium metal deposition / stripping electrochemical test. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0019] In the present application, the term "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural.

[0020] In the present application, "at least one" means one or more, and "a plurality of" means two or more. "At least one of the following" or the like means any combination of these items, including any combination of single item or multiple items.

[0021] It should be understood that in various embodiments of the present application, the size of the sequence number of the above-mentioned processes does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0022] The weight of the related components mentioned in the specification of the embodiments of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of each component. Therefore, as long as the content of the related components in the specification of the embodiments of the present application is enlarged or reduced in proportion, it is within the scope disclosed in the specification of the embodiments of the present application. Specifically, the mass in the specification of the embodiments of the present application can be μg, mg, g, kg and other mass units commonly known in the chemical field.

[0023] As shown in the accompanying Figure 1 The first aspect of the embodiments of the present application provides a lithium metal negative electrode composite current collector, which comprises a metal substrate layer and a transition metal boride layer arranged on at least one surface of the metal substrate layer.

[0024] The lithium metal negative electrode composite current collector provided in the first aspect of the present application has a transition metal boride layer on one surface of the metal substrate layer, which has high electrical conductivity and does not affect the current collector properties of the substrate layer. The transition metal boride layer introduced by the present application on the metal substrate layer of the current collector not only has good interface wetting properties with lithium, but can effectively improve the wettability and bonding force of the lithium metal layer and the current collector; and the transition metal boride has a hexagonal structure, and its (001) crystal face has good lattice matching with lithium metal, which can form an atomic-scale lattice matching with lithium metal, thereby guiding the uniform deposition of lithium metal atoms on the surface of the current collector, inhibiting the growth of lithium dendrites, and effectively improving the safety and stability of the battery.

[0025] In some embodiments, the transition metal in the transition metal boride layer is selected from at least one of the first subgroup, the second subgroup, the third subgroup, the fourth subgroup, the fifth subgroup, the sixth subgroup, the seventh subgroup, and the eighth subgroup of the periodic table. In some embodiments, the transition metal boride in the transition metal boride layer is selected from transition metal diborides. In some specific embodiments, the transition metal boride includes at least one of zirconium diboride, hafnium diboride, vanadium diboride, niobium diboride, tantalum diboride, chromium diboride, molybdenum diboride, tungsten diboride, manganese diboride, technetium diboride, rhenium diboride, iron diboride, ruthenium diboride, osmium diboride, cobalt diboride, rhodium diboride, iridium diboride, and cadmium diboride. These transition metal borides used in the embodiments of the present application, on the one hand, have high electrical conductivity and do not affect the current collection effect of the metal substrate layer of the current collector on the current generated in the battery. On the other hand, the transition metal boride has good interface wetting properties with lithium metal, which can effectively improve the bonding force of lithium metal and the metal substrate layer. On the other hand, these transition metal borides can form an atomic-scale lattice matching with lithium, guide the uniform deposition of lithium metal atoms on the surface of the current collector, and effectively inhibit the growth of lithium dendrites.

[0026] In some embodiments, the thickness of the transition metal boride layer is 0.2 μm to 10 μm, which can effectively ensure the interface wetting / bonding performance, the improvement of the lithium dendrite suppression effect. If the thickness of the transition metal boride layer is too thin, too many defects will be caused, which is easy to cause uneven deposition of lithium, and it is difficult to improve the bonding stability between the metal substrate layer and the lithium metal negative electrode layer, and the suppression effect on the lithium dendrite is not good, and the lithium dendrite surface density increases. If the thickness of the transition metal boride layer is too thick, the volume of the current collector is increased, the overall capacity of the negative electrode sheet is reduced, thereby affecting the overall electrochemical performance of the ion battery. In further embodiments, the thickness of the transition metal boride layer is 1 μm to 4 μm, and the transition metal boride layer with the thickness can better improve the bonding stability between the metal substrate layer and the lithium metal negative electrode sheet, and has a better suppression effect on the lithium dendrite. In some specific embodiments, the thickness of the transition metal boride layer can be 0.2 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10.

[0027] In some embodiments, the metal material in the metal substrate layer includes at least one of copper, iron, nickel, titanium, and the metal substrate layer not only can play a good supporting role for the negative lithium metal, but also the substrate layer made of the metal material does not react with lithium, has an electronic conduction and ionic insulation effect, has an excellent current collection effect on the current generated in the battery, and can collect the current generated in the battery and output externally. Moreover, the lithium ion can be prevented from further diffusing outward, so that the negative electrode has better stability and safety performance, and the float charging and stable cycle ability of the high-energy-density lithium metal negative electrode battery is improved. In some specific embodiments, the metal substrate layer includes one of copper, nickel, iron, titanium, iron-nickel alloy, and iron-titanium-nickel alloy.

[0028] In some embodiments, the lithium metal negative electrode composite current collector includes a metal substrate layer and a transition metal boride layer arranged on opposite surfaces of the metal substrate layer, and by arranging the transition metal boride layer on both sides of the metal substrate layer, the prepared composite current collector is suitable for a wound battery, a stacked battery and other systems, and has more practical value.

[0029] The lithium metal negative electrode composite current collector provided by the embodiments of the present application can be prepared by the following method.

[0030] The second aspect of the embodiments of the present application provides a preparation method of a lithium metal negative electrode composite current collector, including the steps of:

[0031] The metal substrate layer is obtained, and a transition metal boride layer is formed on at least one surface of the metal substrate layer to obtain a lithium metal negative electrode composite current collector.

[0032] The preparation method of the lithium metal negative electrode composite current collector provided in the second aspect of the present application forms the transition metal boride layer on at least one surface of the metal substrate layer, and then the lithium metal negative electrode composite current collector is obtained. The preparation method is simple and suitable for industrial large-scale production and application. When the composite current collector is applied to a lithium ion battery, the lithium metal layer is arranged on the surface of the transition metal boride layer in the composite current collector. Through the intermediate transition metal boride layer, the wettability and bonding force of the lithium metal layer and the metal substrate current collector layer can be improved, and the transition metal boride layer can form an atomic-scale lattice match with the lithium metal, so that the lithium metal layer is more uniformly deposited, thereby effectively inhibiting the growth of lithium dendrites.

[0033] In some embodiments, the step of forming the transition metal boride layer on one surface of the metal substrate layer includes: depositing the transition metal boride on one surface of the metal substrate layer by chemical vapor deposition and / or physical vapor deposition to form the transition metal boride layer. The method for forming the transition metal boride layer on the surface of the metal substrate layer in the embodiments of the present application can be flexibly selected according to actual application conditions. The transition metal boride can be obtained by chemical vapor deposition or physical vapor deposition, or by a combination of the two deposition methods.

[0034] In some embodiments, the conditions for chemical vapor deposition include: performing chemical vapor deposition of the transition metal boride in an inert atmosphere at a temperature of 1000℃ to 1500℃, a pressure of 1.0×10 -3 Pa to 3.0×10 -3 Pa, and a pulse voltage of 3000V to 3300V. The chemical vapor deposition conditions in the embodiments of the present application enable the raw material substances such as the transition metal source and the boron source to chemically react in a gaseous form on the metal substrate layer, and generate the transition metal boride to be deposited on the metal substrate layer to form the transition metal boride layer. The film layer formed is dense, uniform in thickness, smooth in surface, and tightly combined with the metal substrate layer.

[0035] In some embodiments, the conditions for physical vapor deposition include: performing physical vapor deposition of the transition metal boride under the conditions of a working gas pressure of 0.4Pa to 0.8Pa and a sputtering power of 1KW to 3KW. In the embodiments of the present application, the transition metal boride is directly used as a target material, and the dense and uniform transition metal boride layer is formed on the metal substrate layer by sputtering deposition under the physical vapor deposition conditions, and is tightly combined with the metal substrate layer.

[0036] In some embodiments, the preparation method of the lithium metal negative electrode composite current collector can also be: depositing the transition metal boride on both opposite surfaces of the metal substrate layer to simultaneously form the transition metal boride layer on both opposite surfaces of the metal substrate layer, and obtaining the lithium metal negative electrode composite current collector with the transition metal boride layer formed on both opposite surfaces, so that it is more suitable for battery systems such as winding and stacking, and is more widely applied.

[0037] In some embodiments, the transition metal in the transition metal boride layer is selected from at least one of the first subgroup, the second subgroup, the third subgroup, the fourth subgroup, the fifth subgroup, the sixth subgroup, the seventh subgroup, and the eighth subgroup of the periodic table. In some embodiments, the transition metal boride in the transition metal boride layer is selected from a transition metal diboride. In some embodiments, the transition metal boride comprises at least one of zirconium diboride, hafnium diboride, vanadium diboride, niobium diboride, tantalum diboride, chromium diboride, molybdenum diboride, tungsten diboride, manganese diboride, technetium diboride, rhenium diboride, iron diboride, ruthenium diboride, osmium diboride, cobalt diboride, rhodium diboride, iridium diboride, and cadmium diboride.

[0038] In some embodiments, the thickness of the transition metal boride layer is 0.2 μm to 10 μm. In further embodiments, the thickness of the transition metal boride layer is 1 μm to 4 μm.

[0039] In some embodiments, the metal material in the metal substrate layer comprises at least one of copper, iron, nickel, and titanium.

[0040] In some embodiments, the metal substrate layer is selected from one of copper, nickel, iron, titanium, iron-nickel alloy, and iron-titanium-nickel alloy.

[0041] The advantages of the above embodiments of the present application have been described in the foregoing, and will not be repeated here.

[0042] The third aspect of the embodiments of the present application provides a lithium ion battery, comprising a lithium metal anode, the lithium metal anode comprising: a lithium metal layer and a composite current collector arranged on one surface of the lithium metal layer, the composite current collector comprising a metal substrate layer and a transition metal boride layer arranged between the metal substrate layer and the lithium metal layer.

[0043] The lithium ion battery provided by the third aspect of the present application has the composite current collector as the anode current collector, and the transition metal boride layer is arranged between the lithium metal layer and the metal substrate layer, so that the lithium metal layer is combined closely with the composite current collector layer, and the transition metal boride layer can form an atomic-scale lattice match with lithium, so as to effectively inhibit the growth of lithium dendrites. Therefore, the lithium ion battery provided by the embodiments of the present application has good safety and stability, long service life, and has a wider application prospect.

[0044] In the lithium ion battery of the embodiments of the present application, other constituent units such as the positive electrode, the separator, and the electrolyte can be flexibly selected according to actual application conditions, and are not strictly limited here.

[0045] In some embodiments, the transition metal in the transition metal boride layer is selected from at least one of the first subgroup, the second subgroup, the third subgroup, the fourth subgroup, the fifth subgroup, the sixth subgroup, the seventh subgroup, and the eighth subgroup of the periodic table. In some embodiments, the transition metal boride in the transition metal boride layer is selected from transition metal diborides. In some embodiments, the transition metal boride includes at least one of zirconium diboride, hafnium diboride, vanadium diboride, niobium diboride, tantalum diboride, chromium diboride, molybdenum diboride, tungsten diboride, manganese diboride, technetium diboride, rhenium diboride, iron diboride, ruthenium diboride, osmium diboride, cobalt diboride, rhodium diboride, iridium diboride, and cadmium diboride.

[0046] In some embodiments, the thickness of the transition metal boride layer is 0.2 μm to 10 μm. In further embodiments, the thickness of the transition metal boride layer is 1 μm to 4 μm.

[0047] In some embodiments, the metal material in the metal substrate layer includes at least one of copper, iron, nickel, and titanium. In some embodiments, the metal substrate layer includes one of copper, nickel, iron, titanium, iron-nickel alloy, and iron-titanium-nickel alloy.

[0048] The advantages of the above embodiments of the present application have been described in the foregoing, and will not be repeated here.

[0049] In order for the above-described details and operations of the present application to be clearly understood by those skilled in the art, and in order for the significant performance of the lithium metal negative electrode composite current collector and the preparation method thereof to be embodied, the above technical solutions are illustrated by a plurality of embodiments as follows.

[0050] Embodiment 1

[0051] A lithium metal negative electrode composite current collector uses titanium as a base metal material, and titanium diboride as an infiltration layer, wherein the thickness of the titanium diboride infiltration layer is 3 μm. The specific preparation process is as follows:

[0052] (1) Taking titanium foil as the substrate layer material, first plasma cleaning is performed by glow discharge, wherein the working pressure is 0.6 Pa, the bias voltage is -80 V, and the cleaning time is 30 min;

[0053] (2) After cleaning, titanium diboride is used as a sputtering target for sputter deposition, wherein the sputtering power is 1 KW, the working pressure is 0.6 Pa, and the film thickness is controlled to be about 3 μm;

[0054] (3) After step 2 is completed, the titanium diboride target is turned off, and the sample is taken out of the vacuum coating chamber, thereby obtaining the composite current collector.

[0055] Embodiment 2

[0056] A lithium metal negative electrode composite current collector, titanium is used as a base metal material, titanium diboride is used as an infiltration layer, the thickness of the titanium diboride infiltration layer is 3 microns, and the titanium diboride infiltration layer is made by a chemical vapor deposition method. The specific preparation process is as follows:

[0057] (1) Take titanium foil as the base layer material, first put the material into anhydrous ethanol for ultrasonic cleaning, then take it out, dry it and put it into a drying box for standby;

[0058] (2) Open the mechanical pump and molecular pump respectively, when the pressure in the vacuum chamber is reduced to 2.0x10 -3 Pa, open the heater to heat to 100℃ to remove the water vapor in the vacuum cavity, and introduce 100mL / min of argon into the vacuum chamber for 20min to remove the air not extracted. Clean the sample surface with a pulse bias of 3300V for 20min;

[0059] (3) After cleaning, keep the pulse voltage 3100V constant. The selected chemical reaction precursor system is TiCl4-BCl3-H2-Ar, wherein the Ti source is TiCl4 liquid heated to form TiCl4 vapor in a 65℃ water bath, and argon is used as a carrier gas and is transported into the CVD reaction chamber together with other gases. Deposit titanium diboride film on the surface of the titanium foil for 5h to obtain a composite current collector.

[0060] Examples 3-7

[0061] Examples 3-7 respectively provide a lithium metal negative electrode composite current collector based on a titanium diboride infiltration layer, examples 3-7 are the same as example 1 in infiltration layer, preparation steps and test method except that the base layer material used is different; the base layer used is respectively: copper, nickel, iron, iron-nickel alloy, iron-titanium-nickel alloy.

[0062] Examples 8-16

[0063] Examples 8-16 respectively provide a lithium metal negative electrode composite current collector based on a titanium diboride infiltration layer with different thicknesses, examples 8-16 are different from example 1 in that the thickness of the titanium diboride infiltration layer is different, the base layer, the preparation steps and the test method are the same; the thickness of the titanium diboride infiltration layer is respectively: 0.2 microns, 0.5 microns, 1 microns, 2 microns, 4 microns, 5 microns, 6 microns, 8 microns, 10 microns.

[0064] Examples 17-34

[0065] Examples 17-34 provide lithium metal anode composite current collectors based on different transition metal boride wetting layers. The difference between Examples 17-34 and Example 1 is the type of transition metal wetting layer, while the thickness of the wetting layer, the substrate, the preparation steps, and the testing methods are the same. The transition metal wetting layers are zirconium diboride, hafnium diboride, vanadium diboride, niobium diboride, tantalum diboride, chromium diboride, molybdenum diboride, tungsten diboride, manganese diboride, technetium diboride, rhenium diboride, iron diboride, ruthenium diboride, osmium diboride, cobalt diboride, rhodium diboride, iridium diboride, and cadmium diboride.

[0066] Comparative Example 1

[0067] Titanium foil without transition metal boride modification was used as Comparative Example 1.

[0068] Furthermore, to verify the advancements of the lithium metal anode composite current collector and its preparation method in this application, the lithium metal anode composite current collectors prepared in Examples 1-34 were subjected to the following performance tests:

[0069] 1. This application conducted X-ray diffraction tests on the lithium metal anode composite current collector prepared in Example 1, and its XRD pattern is attached. Figure 2 As shown (vertical axis represents intensity), two diffraction peaks appeared. The deposited transition metal boride layer can be identified as titanium diboride by PDF card calibration.

[0070] 2. In this application, the composite current collector with a bilayer structure prepared in Example 1 and the ordinary titanium foil current collector without transition metal boride modification in Comparative Example 1 were respectively immersed in molten lithium metal. After drying, a lithium metal layer was formed on the surface of the current collector. The test results are attached. Figure 3 As shown: A uniform lithium metal layer was formed on the surface of the composite current collector prepared in Example 1, exhibiting good wettability and bonding strength. Figure 3 a); However, the lithium metal layer formed on the surface of ordinary titanium foil in Comparative Example 1 exhibited blistering, and the lithium metal distribution was uneven, resulting in poor wettability and low bonding strength. Figure 3 b).

[0071] 3. This application presents electrochemical tests on the lithium metal deposition / stripping of the composite current collectors prepared in Examples 1 and 2 and the titanium foil without transition metal boride in Comparative Example 1. Specifically, an in-situ optical testing device was used, with a lithium metal sheet as the counter electrode and a half-cell assembled using ethylene carbonate (EC) and diethyl carbonate (DEC) in a 1:1 volume ratio as the electrolyte. After charge-discharge under the same conditions, the surface morphology of the two different current collectors was observed in situ. The test results are attached. Figure 4 As shown: Lithium metal was uniformly deposited on the surface of the composite current collector prepared in Example 1 of this application, and the lithium dendrite surface density was only 1% (Figure 4 a) and a large amount of lithium dendrites (b) are generated on the surface of the ordinary titanium foil. The measured lithium dendrite density is 70%. The lithium dendrite density on the surface of the composite current collector prepared in Example 2 is only 1.2%, which also shows good lithium dendrite inhibition effect. Therefore, the composite current collector prepared in the examples has good lithium dendrite inhibition effect, which can effectively improve the safety stability and service life of the battery system. Figure 4

[0072] 4. The lithium metal deposition / stripping electrochemical tests were carried out on the composite current collectors prepared in Examples 1-7 with different metal base layers, and the lithium dendrite surface density on the surface of the current collector layer was calculated by in-situ optical observation, and the test results are shown in Table 1 below:

[0073] Table 1

[0074]

[0075] From the above test results, it can be seen that the composite current collectors prepared in Examples 1-7 on different metal base layers all have good lithium dendrite inhibition effect, and the lithium dendrite surface density is less than 6%.

[0076] 5. The lithium metal deposition / stripping electrochemical tests were carried out on the composite current collectors prepared in Examples 8-16 with different thicknesses of transition metal borides (titanium diboride), and the lithium dendrite surface density on the surface of the current collector layer was calculated by in-situ optical observation, and the test results are shown in Table 2 below:

[0077] Table 2

[0078]

[0079]

[0080] From the above test results, it can be seen that the composite current collectors prepared in Examples 8-16 with different thicknesses of titanium diboride layer, the thickness between 0.2-10 microns, all have good lithium dendrite inhibition effect, and the lithium dendrite surface density is less than 10%. And when the thickness of the titanium diboride layer is 1-4 microns, there is a better lithium dendrite inhibition effect, and the lithium dendrite surface density is less than 3%.

[0081] 6. The lithium metal deposition / stripping electrochemical tests were carried out on the composite current collectors prepared in Examples 17-34 with different transition metal borides, and the lithium dendrite surface density on the surface of the current collector layer was calculated by in-situ optical observation, and the test results are shown in Table 3 below:

[0082] Table 3

[0083] ​

[0084]

[0085] From the test results, the lithium dendrite surface density of the composite current collectors prepared by the transition metal borides of the application 17-34 is less than 10%, and all have good lithium dendrite inhibition effect.

[0086] The above only describes the preferred embodiments of the application and is not intended to limit the application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A lithium metal anode, characterized in that, include: A lithium metal layer and a composite current collector disposed on one surface of the lithium metal layer, the composite current collector comprising: a metal substrate layer and at least one transition metal boride layer disposed on one surface of the metal substrate layer; The transition metal boride layer has a hexagonal structure, and its (001) crystal plane can form an atomic-scale lattice match with lithium metal, guiding lithium metal atoms to be uniformly deposited on the surface of the current collector and inhibiting the growth of lithium dendrites.

2. The lithium metal anode as described in claim 1, characterized in that, In the transition metal boride layer, the transition metal boride is selected from transition metal diborides.

3. The lithium metal anode as described in claim 2, characterized in that, The transition metal borides include at least one of the following: zirconium diboride, hafnium diboride, vanadium diboride, niobium diboride, tantalum diboride, chromium diboride, molybdenum diboride, tungsten diboride, manganese diboride, technetium diboride, rhenium diboride, iron diboride, ruthenium diboride, osmium diboride, cobalt diboride, rhodium diboride, iridium diboride, and cadmium diboride.

4. The lithium metal anode as described in any one of claims 1 to 3, characterized in that, The thickness of the transition metal boride layer is 0.2 μm to 10 μm.

5. The lithium metal anode as described in claim 4, characterized in that, The metal substrate layer contains at least one of the following metal materials: copper, iron, nickel, and titanium.

6. The lithium metal anode as described in claim 5, characterized in that, The thickness of the transition metal boride layer is 1 μm to 4 μm; And / or, the metal substrate layer includes one of the following: copper, nickel, iron, titanium, iron-nickel alloy, and iron-titanium-nickel alloy.

7. A method for preparing a lithium metal anode as described in any one of claims 1 to 6, characterized in that, The preparation of the composite current collector includes the following steps: A metal substrate layer is obtained, and a transition metal boride layer is formed on at least one surface of the metal substrate layer to obtain the composite current collector.

8. The method for preparing a lithium metal anode as described in claim 7, characterized in that, The step of forming a transition metal boride layer on a surface of the metal substrate includes: depositing a transition metal boride on a surface of the metal substrate using chemical vapor deposition and / or physical vapor deposition to form the transition metal boride layer.

9. The method for preparing the lithium metal anode as described in claim 8, characterized in that, The conditions for chemical vapor deposition include: a temperature of 1000℃~1500℃ and a pressure of 1.0×10⁻⁶. -3 Pa ~3.0×10 -3 Chemical vapor deposition of the transition metal boride was carried out under an inert atmosphere with a pulse voltage of 3000V~3300V. And / or, the physical vapor deposition conditions include: physical vapor deposition of the transition metal boride under working gas pressure of 0.4 Pa to 0.8 Pa and sputtering power of 1 kW to 3 kW.

10. A lithium-ion battery, characterized in that, Including the lithium metal anode as described in any one of claims 1 to 6.

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