Current collector, method for producing the same, electrode, and method for producing the same

Abstract

The application provides a current collector and a preparation method thereof, an electrode and a preparation method thereof. The current collector comprises a three-dimensional substrate and a lithiumophilic coating layer covering the surface of the three-dimensional substrate. The three-dimensional substrate is a three-dimensional conductive framework. The lithiumophilic coating layer has a plurality of densely distributed nanoparticles, and the nanoparticles are coated on the surface of the three-dimensional substrate. The three-dimensional substrate is modified by the lithiumophilic coating layer, which can be used as a host material of lithium metal. The lithiumophilic coating layer can promote uniform nucleation and deposition of lithium metal on the surface of the current collector, prevent the growth of lithium dendrites, and provide space for deposition and embedding of lithium metal due to the hierarchical structure of the three-dimensional substrate. The gap between adjacent two nanoparticles, together with the hierarchical structure of the three-dimensional substrate, provides space for volume expansion of lithium metal during deposition or circulation, effectively alleviates the volume expansion of lithium metal, and thus improves the cycle stability of the lithium metal electrode. The current collector has a large specific surface area, which can effectively disperse the current density and regulate uniform lithium deposition.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of lithium battery, more particularly, relates to a current collector and a preparation method thereof, an electrode and a preparation method thereof. BACKGROUND

[0002] Lithium ion battery is now gradually becoming the main energy storage device, which is widely used in electronic devices such as unmanned aerial vehicle, mobile phone, notebook computer and electric vehicle. However, the graphite used as negative electrode material of lithium ion battery is limited by its theoretical specific capacity (372 mAh.g -1 ), which affects the overall energy density of lithium ion battery. Therefore, it is necessary to develop new negative electrode materials with higher energy density. Metal lithium negative electrode is considered to be an excellent lithium battery negative electrode material due to its extremely high theoretical specific capacity (3860 mAh.g -1 ), the lowest electrochemical potential (-3.04 V vs standard hydrogen electrode) and low weight density (0.534 g.cm -3 ).

[0003] However, there are still some problems in using lithium metal as negative electrode material: (1) the lithium metal surface is prone to uneven lithium deposition during continuous electrodeposition, which may lead to dendritic lithium crystals, easily puncture the separator and cause short circuit of the battery, resulting in safety problems; (2) due to the nature of lithium metal negative electrode without host, serious volume expansion and contraction problems may occur during repeated charge and discharge process, which leads to continuous reconstruction of electrode / electrolyte interface film, reduces the coulombic efficiency and cycle life of the battery.

[0004] In order to solve the above problems, researchers have made a lot of efforts. Considering the poor mechanical properties and chemical instability of the original SEI film (solidelectrolyte interphase), scientists have carried out surface modification on lithium metal negative electrode to control the formation of SEI film and inhibit the growth of dendrites by adjusting the electrolyte. Such as adding electrolyte additives, using solid electrolyte and constructing artificial SEI film. However, due to the nature of lithium metal negative electrode without host, these methods cannot fundamentally alleviate the problem of volume expansion of lithium metal negative electrode during the cycle process, which eventually leads to the rupture of SEI film. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a current collector and a preparation method thereof, to solve the technical problems that lithium dendrites are generated when lithium metal is used as negative electrode material, the separator is punctured, and the volume expansion of lithium metal leads to the damage of the separator.

[0006] Another purpose of the present application is to provide an electrode.

[0007] Yet another object of the present application is to provide a method for preparing an electrode.

[0008] In order to achieve the above objects, the technical solutions of the present application are as follows.

[0009] A current collector comprises a three-dimensional substrate and a lithium-philic coating layer covering the surface of the three-dimensional substrate, the three-dimensional substrate being a three-dimensional conductive framework, and the lithium-philic coating layer having a plurality of densely packed nanoparticles, the nanoparticles being coated on the surface of the three-dimensional substrate.

[0010] Optionally, the lithium-philic coating layer comprises a metal carbide layer and a carbon coating layer, the metal carbide layer being formed by a plurality of metal carbide particles and being combined to the surface of the three-dimensional substrate, and the carbon coating layer covering the surface of the metal carbide layer.

[0011] Optionally, the carbon coating layer is composed of upright graphene or amorphous carbon.

[0012] Optionally, the method for preparing the metal carbide layer comprises: in-situ reaction of an acid solution and / or a salt solution containing metal ions and the surface of the three-dimensional substrate to generate the metal carbide layer on the surface of the three-dimensional substrate.

[0013] Optionally, the acid solution contains one or more of molybdenum, nickel, iron and cobalt; and / or, the salt solution contains one or more of molybdenum, nickel, iron and cobalt.

[0014] Optionally, the acid solution contains one or more of molybdate, phosphomolybdate and dialkyldithioaminomethylphosphonate molybdenum; and / or, the salt solution contains one or more of ammonium molybdate, ammonium thiomolybdate and ammonium molybdenum-nickel heteropoly acid.

[0015] Optionally, the three-dimensional substrate is a three-dimensional carbon framework.

[0016] Further, a method for preparing a current collector comprises the following steps:

[0017] functionalizing the surface of the three-dimensional substrate;

[0018] immersing the functionalized three-dimensional substrate in an acid solution and / or a salt solution containing metal ions, ultrasonicating, and standing to adsorb, so that the three-dimensional substrate adsorbs the metal ions and the acid and / or the salt in the acid solution and / or the salt solution;

[0019] taking out the three-dimensional substrate after adsorption, and washing and drying the three-dimensional substrate;

[0020] heat-treating the dried three-dimensional substrate under the protection of an inert gas, so that the adsorbed metal ions and the acid and / or the salt react in-situ with the surface of the three-dimensional substrate to generate a metal carbide layer on the surface of the three-dimensional substrate, and a current collector preliminary product is obtained;

[0021] The current collector preliminary product is placed in a reaction furnace, and a carbon source gas is introduced to generate a carbon coating layer on the surface of the metal carbide layer through plasma enhanced chemical vapor deposition.

[0022] Also, an electrode comprises metal lithium and the current collector as described above, and the metal lithium is deposited on the surface of the current collector.

[0023] Also, a preparation method of an electrode comprises the following steps:

[0024] The metal lithium is deposited on the surface of the current collector as described above by using an electrochemical deposition method or a melt infusion method.

[0025] 1. The current collector provided by the application is modified by a lithium-philic coating layer on a three-dimensional substrate, and can be used as a host material of lithium metal to make a lithium metal electrode. The lithium-philic coating layer can promote uniform nucleation and deposition of lithium metal on the surface of the current collector and prevent the growth of lithium dendrites. The hierarchical structure of the three-dimensional substrate can provide space for deposition and embedding of lithium metal. In addition, there is a gap between two adjacent nanoparticles of the lithium-philic coating layer, which, together with the hierarchical structure of the three-dimensional substrate, provides space for volume expansion of lithium metal during deposition or cycling, effectively alleviates the volume expansion of lithium metal, and thus improves the cycle stability of the lithium metal electrode. Moreover, the current collector provided by the application has a large specific surface area, which can effectively disperse the current density and regulate uniform lithium deposition. The method of combining a three-dimensional substrate with a lithium-philic coating layer solves the problem that the previous lithium metal negative electrode is difficult to balance the problems of powdering in the bulk phase and uneven growth at the interface, and provides an effective solution for the actual industrialization of the lithium metal negative electrode.

[0026] 2. The preparation method of the current collector provided by the application modifies the surface of the composite lithium negative electrode by in-situ carbonization combined with physical enhancement of plasma enhanced chemical vapor deposition. The composition and thickness of the lithium-philic coating layer are controllable, and the cycle life of the lithium negative electrode is effectively prolonged.

[0027] 3. The electrode provided by the application uses metal lithium as an electrode material, and the current collector provided by the application is used as a host material of lithium metal, which can effectively prevent the growth of lithium dendrites and alleviate the volume expansion of lithium metal, and thus improves the cycle stability of the electrode.

[0028] 4. The preparation method of the electrode provided by the application is simple in process and easy to control in conditions, and is suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0029] The application will be further described below in combination with the drawings and examples, and the drawings show:

[0030] Figure 1 It is a scanning electron microscope picture of the current collector provided by Example 1 of the application without lithium deposition;

[0031] Figure 2A scanning electron microscope picture of the cross section of the current collector without lithium deposition provided in Example 1 of the present application;

[0032] Figure 3 The electrode of Example 1 of the present application, Comparative Example 1 and Comparative Example 2 were tested for the coulombic efficiency at 1 mA.cm-2. -2 A comparison chart of the coulombic efficiency at different current densities;

[0033] Figure 4 A cycle stability test chart of the electrode of Example 1 of the present application;

[0034] Figure 5 A scanning electron microscope picture of the three-dimensional carbon cloth of Example 1 of the present application and Comparative Example 1. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved in the present application more clear and explicit, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0036] The current collector provided in the embodiments of the present application comprises a three-dimensional substrate and a lithiumophilic coating layer coated on the surface of the three-dimensional substrate, the three-dimensional substrate is a three-dimensional conductive framework, and the lithiumophilic coating layer has a plurality of densely packed nanoparticles, which are coated on the surface of the three-dimensional substrate.

[0037] The current collector described above uses the lithiumophilic coating layer to modify the surface of the three-dimensional substrate, which can be used as a host material for lithium metal and used to make a lithium metal electrode. The lithiumophilic coating layer can promote uniform nucleation and deposition of lithium metal on the surface of the current collector and prevent the growth of lithium dendrites. The hierarchical structure of the three-dimensional substrate provides space for the deposition and intercalation of lithium metal. In addition, the gaps between the plurality of nanoparticles of the lithiumophilic coating layer, together with the hierarchical structure of the three-dimensional substrate, provide space for the volume expansion of lithium metal during deposition or cycling, effectively alleviate the volume expansion of lithium metal, and thus improve the cycle stability of the lithium metal electrode. The lithiumophilic coating layer has a plurality of nanoparticles, so that the current collector has a large specific surface area, can effectively disperse the current density, and can regulate uniform lithium deposition.

[0038] The current collector of the embodiments of the present application, which combines the three-dimensional substrate with the lithiumophilic coating layer, also solves the problem that the previous lithium metal negative electrode is difficult to balance the bulk pulverization and the non-uniform growth at the interface, and provides an effective solution for the actual industrialization of the lithium metal negative electrode.

[0039] In the embodiments of the present application, the nanoparticles refer to nanometer particles with a size of less than 500 nm, and there is a certain gap between two adjacent nanoparticles.

[0040] Optionally, the lithiumophilic coating layer comprises a metal carbide layer and a carbon coating layer, the metal carbide layer is formed by a plurality of metal carbide nanoparticles and is combined to the surface of the three-dimensional substrate, and the carbon coating layer is coated on the surface of the metal carbide layer. It can be understood that the plurality of nanoparticles are metal carbide nanoparticles. The metal carbide layer and the carbon coating layer cooperate, the carbon coating layer can disperse the electric field and the current density, make the lithium ion distribution more uniform, and promote the uniform deposition of lithium metal. From the perspective of nucleation and deposition, the synergistic effect of the carbon coating layer and the lithium ion can effectively inhibit the growth of lithium dendrites; the metal lithium can form lithium carbide with the carbon in the carbon coating layer, the metal carbide layer can form an alloy with the lithium carbide in situ, further serving as a reversible lithium deposition site, reducing the lithium nucleation overpotential, and inducing uniform lithium deposition and stripping.

[0041] Optionally, the carbon coating layer is composed of upright graphene or amorphous carbon.

[0042] Optionally, the preparation method of the metal carbide layer comprises: using an acid solution and / or a salt solution containing metal ions and the surface of the three-dimensional substrate to react in situ to generate a metal carbide layer on the surface of the three-dimensional substrate. The metal carbide layer is a substance formed by the in-situ growth of the acid solution and / or the salt solution containing metal ions and the surface of the three-dimensional substrate. The metal carbide naturally extends outward from the connection between the metal carbide and the three-dimensional substrate to form metal carbide nanoparticles. The densely packed plurality of metal carbide nanoparticles constitute the metal carbide layer.

[0043] According to the reaction characteristics of the acid solution and / or the salt solution containing metal ions and the three-dimensional substrate, the generated metal carbide layer comprises a plurality of densely packed metal carbide nanoparticles. This structure is beneficial to the in-situ reaction of the metal carbide layer with lithium metal or lithium carbide to form an alloy.

[0044] Optionally, the acid solution containing metal ions contains one or more of molybdenum, nickel, iron, and cobalt; and / or, the salt solution contains one or more of molybdenum, nickel, iron, and cobalt. The acid solution or the salt solution containing the metals can generate corresponding metal carbide with the three-dimensional substrate to form the metal carbide layer.

[0045] Optionally, the acid solution may, for example, include one or more of molybdic acid, phosphomolybdic acid, and dialkyldithioaminomethyl molybdenum acid; and the salt solution may, for example, include one or more of ammonium molybdate, ammonium thiomolybdate, ammonium molybdenum nickel heteropoly acid, molybdenum phosphorus iron heteropoly acid salt, and cobalt molybdenum heteropoly acid. The acid solution or the salt solution containing molybdenum can generate molybdenum carbide with the three-dimensional substrate. The molybdenum carbide has good directivity and good thermal stability, and can adapt to subsequent high-temperature processes.

[0046] Optionally, the three-dimensional substrate is a three-dimensional carbon skeleton, and the three-dimensional carbon skeleton is a three-dimensional skeleton with stable properties and good electrical conductivity. The three-dimensional carbon skeleton may, for example, include one or more of a three-dimensional carbon fiber, a three-dimensional graphene, a three-dimensional carbon nanotube foam, a three-dimensional carbon cloth, and a three-dimensional electrospun fiber cloth, and the hierarchical structure of the three-dimensional substrate can effectively alleviate the volume expansion of lithium metal during the cycle process. The carbon element in the three-dimensional carbon skeleton can form a metal carbide layer with the metal in the acid solution and / or the salt solution.

[0047] The application also provides a preparation method of the above-mentioned current collector, including the following steps:

[0048] S100: performing functionalization treatment on the surface of the three-dimensional substrate.

[0049] Optionally, the method for performing functionalization treatment on the surface of the three-dimensional substrate includes the following steps: placing the three-dimensional substrate in a plasma cleaning machine, introducing a gas, and functionalizing the surface of the three-dimensional substrate.

[0050] Optionally, the introduced gas is air, which is used to functionalize the surface of the three-dimensional substrate, so that the surface of the three-dimensional substrate has hydrophilicity, which helps to adsorb metal ions, acid and / or salt in the subsequent process, and improves the reaction efficiency of the metal ions, acid and / or salt with the three-dimensional substrate.

[0051] It can be understood that the time for introducing the gas can be adjusted according to the amount and porosity of the three-dimensional substrate, so that the surface of the three-dimensional substrate is reasonably functionalized. Generally, it can be selected as 8-60 min.

[0052] S200: immersing the functionalized three-dimensional substrate into an acid solution and / or a salt solution containing metal ions, ultrasonicating, and standing for adsorption, so that the three-dimensional substrate adsorbs metal ions, acid and / or salt.

[0053] The acid solution and / or the salt solution are prepared by adding acid or salt into deionized water and stirring to dissolve. The mass ratio of the acid to the deionized water is selected as (0.05:1)-(1.5:1); and / or, the mass ratio of the salt to the deionized water is selected as (0.05:1)-(1.5:1).

[0054] The acid or salt is selected from the acid or salt containing one or more of molybdenum, nickel, iron, and cobalt provided in the above.

[0055] The standing time for adsorption can be adjusted according to the adsorption rate and the amount of the metal ions, acid and / or salt required to be adsorbed. Generally, it can be selected as 4-12 h.

[0056] S300: taking out the adsorbed three-dimensional substrate, and performing washing and drying treatment.

[0057] The washing agent used in the washing can be anhydrous ethanol and / or water, and the drying treatment can be heating drying or freeze drying. The temperature of the heating drying is generally below 150 DEG C to avoid decomposition of the acid or the salt, or premature reaction to form metal carbide under the protection of inert gas, thereby affecting the formation mode of the metal carbide layer.

[0058] S400: The dried three-dimensional substrate is subjected to heat treatment under the protection of inert gas to react the adsorbed metal ions, acid and / or salt with the surface of the three-dimensional substrate in situ, generate a metal carbide layer on the surface of the three-dimensional substrate, and obtain a current collector preliminary product.

[0059] Optionally, the inert gas used in the heat treatment is argon or argon-hydrogen mixed gas, and the heat treatment temperature is 500 DEG C-900 DEG C. The heat treatment time can be adjusted according to the generation of the metal carbide layer, and is generally selected to be 2-4 h.

[0060] S500: The current collector preliminary product is placed in a reaction furnace, and a carbon source gas is introduced to generate a carbon coating layer on the surface of the metal carbide layer by plasma enhanced chemical vapor deposition.

[0061] Optionally, the carbon source gas includes methane and / or acetylene.

[0062] Optionally, the temperature of the plasma enhanced chemical vapor deposition is 400 DEG C-700 DEG C, and the treatment time can be adjusted according to the thickness requirement of the carbon coating layer, and is generally selected to be 0.2-1 h.

[0063] The preparation method of the current collector provided in the embodiments of the present application can modify the surface of the composite lithium negative electrode by in-situ carbonization combined with physical enhancement of plasma enhanced chemical vapor deposition, the composition and thickness of the coating layer are controllable, and the cycle life of the lithium negative electrode is effectively prolonged.

[0064] The embodiments of the present application also provide an electrode including metal lithium and the above-mentioned current collector, and the metal lithium is deposited on the surface of the current collector. With the metal lithium as the electrode material and the current collector as the host material of the lithium metal, the growth of lithium dendrites can be effectively prevented, the volume expansion of the lithium metal is relieved, and the cycle stability of the electrode is improved.

[0065] The embodiments of the present application also provide a preparation method of the above-mentioned electrode, including the following steps.

[0066] S600: The metal lithium is embedded in the pores of any one of the above-mentioned current collectors by an electrochemical deposition method or a melt infusion method, and is deposited on the surface of the current collector.

[0067] The process is simple, the conditions are easy to control, and is suitable for industrial production.

[0068] The embodiments of the present application also provide a lithium battery including the above-mentioned electrode, and the above-mentioned electrode can be used as the negative electrode of the lithium battery.

[0069] The lithium battery provided by the embodiment of the application uses metal lithium as electrode material, has high energy density, good uniformity and stable cycle, and can be applied to electronic devices in multiple fields such as mobile terminal products, electric vehicles, power grids and electric tools, and serves as power supply devices for the electronic devices.

[0070] The following embodiments are used to illustrate the current collector and the preparation method thereof, the electrode and the preparation method thereof, the lithium battery and the application thereof and the product thereof, and the performance of the product.

[0071] Embodiment 1

[0072] The preparation method of the electrode of the embodiment includes the following steps:

[0073] S100: Place the three-dimensional carbon cloth in a plasma cleaning machine, and pass in air, so as to functionalize the surface of the three-dimensional carbon cloth at a power of 25 W for 10 min.

[0074] S150: Add 2 g of phosphomolybdic acid into 20 mL of deionized water, and stir to dissolve, to obtain a phosphomolybdic acid solution.

[0075] S300: Take out the three-dimensional carbon cloth after adsorbing the phosphomolybdic acid, and wash with anhydrous ethanol and water, and freeze-dry,

[0076] S400: Heat treat the dried three-dimensional carbon cloth in an argon atmosphere at 800 ℃ for 3 h at a heating rate of 5 ℃ / min, so that the adsorbed phosphomolybdic acid reacts in situ with the surface of the three-dimensional carbon cloth, a metal carbide layer is generated on the surface of the three-dimensional carbon cloth, and a current collector preliminary product is obtained.

[0077] S500: Place the current collector preliminary product in a tube furnace, and pass in methane gas, so as to grow a coating of upright graphene on the surface of the metal carbide layer by plasma-enhanced chemical vapor deposition at a temperature of 500 ℃ for 20 min, the upright graphene constitutes a carbon coating layer, and a current collector is obtained.

[0078] The scanning electron microscope photos of the current collector are as follows: Figure 1 and Figure 2 wherein, Figure 1 is a scanning electron microscope photo of the current collector before lithium is deposited, Figure 2 is a scanning electron microscope photo of the cross section of the current collector before lithium is deposited, and it can be seen that the upright graphene uniformly coats the three-dimensional carbon cloth.

[0079] S600: Assemble a half battery by using the current collector as a positive electrode and a metal lithium sheet as a negative electrode, and use an electrolyte containing 1 mol / L LiPF6. -1A solution of lithium trifluoromethanesulfonimide in ethylene glycol dimethyl ether and 1,3-dioxolane (volume ratio 1:1) with 1 wt% LiNO3 was discharged at a current density of 1 mA.cm -2 for 5 h, depositing lithium metal on the current collector in an amount of 5 mAh.cm -2 to obtain an electrode.

[0080] Example 2

[0081] The preparation method of the electrode of this example comprises the following steps:

[0082] S100: Place the three-dimensional graphene in a plasma cleaning machine, and pass in air, functionalize the surface of the three-dimensional graphene at a power of 28 W for 15 min.

[0083] S150: Add 8 g of ammonium molybdate to 20 mL of deionized water, stir to dissolve, and obtain an ammonium molybdate solution.

[0084] S300: Take out the three-dimensional graphene after adsorbing ammonium molybdate, and wash with anhydrous ethanol and freeze-dry.

[0085] S400: Heat treat the dried three-dimensional graphene in an argon-hydrogen mixed gas atmosphere at 650°C for 4 h at a heating rate of 6°C / min, so that the adsorbed ammonium molybdate reacts in situ with the surface of the three-dimensional substrate, a metal carbide layer is generated on the surface of the three-dimensional graphene, and a current collector preliminary product is obtained.

[0086] S500: Place the current collector preliminary product in a tube furnace, pass in methane gas, and grow a coating of upright graphene on the surface of the metal carbide layer by plasma-enhanced chemical vapor deposition at 700°C for 30 min, the upright graphene constitutes a carbon coating layer, and a current collector is obtained.

[0087] S600: Assemble a half-cell with the current collector as the positive electrode, a lithium metal sheet as the negative electrode, and an electrolyte containing 1.2 mol.L -1 A solution of lithium trifluoromethanesulfonimide in ethylene glycol dimethyl ether and 1,3-dioxolane (volume ratio 1:1) with 1 wt% LiNO3 was discharged at a current density of 1 mA.cm -2 for 5.5 h, depositing lithium metal on the current collector in an amount of 6 mAh.cm -2 to obtain an electrode.

[0088] Example 3

[0089] The preparation method of the electrode of this example comprises the following steps:

[0090] S100: Place the three-dimensional carbon fiber in a plasma cleaner, introduce air, and process it at 22W power for 40 minutes to functionalize the surface of the three-dimensional carbon fiber.

[0091] S150: Add 10g of molybdic acid and ammonium thiomolybdate (mass ratio 1:1) to 20mL of deionized water, stir to dissolve, and obtain a mixed solution of molybdic acid and ammonium thiomolybdate.

[0092] S200: The functionalized three-dimensional carbon fiber is immersed in a mixed solution of molybdic acid and ammonium thiomolybdate, sonicated for 35 minutes, and allowed to stand for 12 hours to adsorb molybdic acid and ammonium thiomolybdate.

[0093] S300: The three-dimensional carbon fibers after adsorbing molybdic acid and ammonium thiomolybdate are removed, washed with anhydrous ethanol and water, and then freeze-dried.

[0094] S400: The dried three-dimensional carbon fiber is heat-treated at 900℃ for 2 hours in an argon atmosphere with a heating rate of 6℃ / min. This allows the adsorbed molybdic acid and ammonium thiomolybdate to react in situ with the surface of the three-dimensional carbon fiber, forming a metal carbide layer on the surface of the three-dimensional carbon fiber, thus obtaining the initial product of the current collector.

[0095] S500: The initial current collector product is placed in a tube furnace, acetylene gas is introduced, and plasma-enhanced chemical vapor deposition is performed at 400°C for 45 minutes to grow and coat amorphous carbon on the surface of the metal carbide layer. The amorphous carbon forms a carbon coating layer, thus obtaining the current collector.

[0096] S600: A half-cell is assembled using a current collector as the positive electrode and a lithium metal sheet as the negative electrode. The electrolyte contains 1.5 mol / L... -1 A solution of lithium trifluoromethanesulfonylimide in ethylene glycol dimethyl ether and 1,3-dioxolane (volume ratio 1:1) was prepared by adding 1 wt% LiNO3 at 1.2 mA / cm². -2 Discharged at a current density for 5 hours, lithium metal was deposited on the surface of the current collector, with a deposited amount of 6 mAh.cm⁻¹. -2 Electrodes are obtained.

[0097] Example 4

[0098] The electrode preparation method in this embodiment includes the following steps:

[0099] S100: Place the three-dimensional carbon nanotube foam in a plasma cleaner, introduce air, and process it at 25W power for 60 minutes to functionalize the surface of the three-dimensional carbon nanotube foam.

[0100] S150: Add 20g of molybdenum nickel heteropolyacid ammonium to 20mL of deionized water, stir to dissolve, and obtain molybdenum nickel heteropolyacid ammonium solution.

[0101] S200: immerse the functionalized three-dimensional carbon nanotube foam into the ammonium molybdonickel heteropoly acid solution, ultrasonic for 30 min, and stand for 12 h to allow the three-dimensional carbon nanotube foam to adsorb the ammonium molybdonickel heteropoly acid.

[0102] S300: take out the three-dimensional carbon nanotube foam after adsorbing the ammonium molybdonickel heteropoly acid, and wash and freeze-dry the three-dimensional carbon nanotube foam by using anhydrous ethanol and water.

[0103] S400: heat the dried three-dimensional carbon nanotube foam at 750℃ for 3 h in an argon atmosphere at a heating rate of 5℃ / min to allow the adsorbed ammonium molybdonickel heteropoly acid to react in situ with the surface of the three-dimensional carbon nanotube foam, generate a metal carbide layer on the surface of the three-dimensional carbon nanotube foam, and obtain a current collector preliminary product.

[0104] S500: place the current collector preliminary product in a tube furnace, introduce methane, grow a carbon-coated layer on the surface of the metal carbide layer by plasma-enhanced chemical vapor deposition at 700℃ for 60 min, and obtain a current collector.

[0105] S600: melt the metallic lithium to obtain a metallic lithium melt, immerse the current collector in the metallic lithium melt for 1 h to allow the metallic lithium to fill the pores of the current collector and deposit on the surface of the current collector, then take out and cool to obtain an electrode.

[0106] Example 5

[0107] The preparation method of the electrode of the present example comprises the following steps:

[0108] S100: place the three-dimensional graphene in a plasma cleaning machine, introduce air, and treat the three-dimensional graphene at a power of 24 W for 50 min to functionalize the surface of the three-dimensional graphene.

[0109] S150: add 10 g of dialkyldithiocarbamic acid to 20 mL of deionized water, stir to dissolve, and obtain a dialkyldithiocarbamic acid solution.

[0110] S200: immerse the functionalized three-dimensional graphene in the dialkyldithiocarbamic acid solution, ultrasonic for 35 min, and stand for 4 h to allow the three-dimensional graphene to adsorb the dialkyldithiocarbamic acid.

[0111] S300: take out the three-dimensional graphene after adsorbing the dialkyldithiocarbamic acid, and wash and dry the three-dimensional graphene by using anhydrous ethanol and water at 100℃.

[0112] S400: The dried three-dimensional graphene is heat-treated at 500℃ for 4 hours in an argon-hydrogen mixed atmosphere with a heating rate of 4℃ / min. This allows the adsorbed dialkyldithioaminomolybdic acid to react in situ with the surface of the three-dimensional graphene, forming a metal carbide layer on the surface of the three-dimensional graphene, thus obtaining the initial current collector product.

[0113] S500: The initial current collector product is placed in a tube furnace, methane gas is introduced, and plasma-enhanced chemical vapor deposition is performed at 450°C for 1 hour to grow and coat vertical graphene on the surface of the metal carbide layer. The vertical graphene constitutes a carbon coating layer, thus obtaining the current collector.

[0114] S600: Melt lithium metal to obtain a lithium metal melt, immerse the current collector in the lithium metal melt for 1.5 hours to allow the lithium metal to fill the pores of the current collector and deposit on the surface of the current collector. Then, remove it, cool it and obtain the electrode.

[0115] Comparative Example 1

[0116] The preparation method of this comparative electrode includes the following steps:

[0117] A half-cell was assembled using three-dimensional carbon cloth as the positive electrode and lithium metal sheet as the negative electrode. The electrolyte contained 1 mol / L of... -1 A solution of lithium trifluoromethanesulfonylimide in ethylene glycol dimethyl ether and 1,3-dioxolane (volume ratio 1:1) was prepared by adding 1 wt% LiNO3 at 1 mA / cm². -2 Discharged at a current density for 5 hours, lithium metal was deposited on the surface of the current collector, with a deposited amount of 5 mAh.cm⁻¹. -2 The electrode of Comparative Example 1 was obtained.

[0118] Scanning electron microscope images of three-dimensional carbon cloth, such as... Figure 3 As shown, the surface structure of the three-dimensional carbon cloth is different from the surface structure of the current collector in Example 1.

[0119] The three-dimensional carbon cloth used in Comparative Example 1 and the three-dimensional carbon cloth used in Example 1 are made of the same material.

[0120] Comparative Example 2

[0121] The electrode preparation method of this comparative example includes the following steps:

[0122] The three-dimensional carbon cloth was placed in a plasma cleaner, air was introduced, and it was treated for 10 minutes at 25W power to functionalize its surface.

[0123] Add 2g of phosphomolybdic acid to 20mL of deionized water and stir to dissolve to obtain a phosphomolybdic acid solution.

[0124] The functionalized three-dimensional carbon cloth was immersed in a phosphomolybdic acid solution, sonicated for 30 minutes, allowed to stand at room temperature for 6 hours, washed with anhydrous ethanol and deionized water, and then freeze-dried.

[0125] The dried three-dimensional carbon cloth was heat-treated at 800℃ for 3 hours in an argon atmosphere with a heating rate of 5℃ / min to obtain a sample of molybdenum carbide modified three-dimensional carbon cloth.

[0126] Using the above-mentioned molybdenum carbide-modified three-dimensional carbon cloth sample as the positive electrode and a lithium metal sheet as the negative electrode, a half-cell was assembled. The electrolyte contained 1 mol / L of... -1 A solution of lithium trifluoromethanesulfonylimide in ethylene glycol dimethyl ether and 1,3-dioxolane (volume ratio 1:1) was prepared by adding 1 wt% LiNO3 at 1 mA / cm². -2 Discharging at a current density for 5 hours resulted in a lithium metal deposition amount of 5 mAh.cm³. -2 .

[0127] Two electrodes from Example 1 were used as the two electrodes of a lithium battery and assembled into a symmetrical battery, designated as Battery No. 1.

[0128] Two electrodes from Comparative Example 1 were used as the two electrodes of a lithium battery and assembled into a symmetrical battery, which is battery number 2.

[0129] Two electrodes from Comparative Example 2 were used as the two electrodes of a lithium battery and assembled into a symmetrical battery, which is battery number 3.

[0130] Battery 1, Battery 2, and Battery 3 were respectively placed in a 2mA cm... -2 Charge-discharge cycle tests were conducted at a current density of 1 mAh / cm³. -2 The electrodes of Example 1, Comparative Example 1, and Comparative Example 2 were tested at 1 mAh.cm. -2 The coulombic efficiency at current density is shown in the test results. Figure 4 As shown. From Figure 4 It can be seen that the coulombic efficiency of the electrode in Example 1 is uniform and stable, indicating that the deposition of lithium metal in the current collector is uniform and stable, and no lithium dendrites are generated. However, the coulombic efficiency of Comparative Example 1 and Comparative Example 2 jumps and is not stable enough, indicating that the deposition of lithium metal is not uniform and stable enough.

[0131] Cyclic stability tests were performed on battery No. 1, and the results are as follows: Figure 5 As shown, the cycle time of battery No. 1 can reach more than 650 hours.

[0132] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A current collector characterized by: The lithium-ion-philic coating layer is formed on the surface of the three-dimensional substrate, and the three-dimensional substrate is a three-dimensional conductive framework. The preparation method of the metal carbide layer comprises the following steps: using an acid solution containing metal ions and / or a salt solution and the surface of the three-dimensional substrate to generate the metal carbide layer on the surface of the three-dimensional substrate in situ. The acid solution comprises one or more of molybdic acid, phosphomolybdic acid, and dialkyldithioaminomethyl molybdenum acid; and the salt solution comprises one or more of ammonium molybdate, ammonium thiomolybdate, and ammonium molybdenum nickel heteropoly acid.

2. The method of making a current collector of claim 1, wherein: The method comprises the following steps: functionalizing the surface of the three-dimensional substrate; immersing the functionalized three-dimensional substrate in an acid solution containing metal ions and / or a salt solution, and performing ultrasonic treatment, standing and adsorbing, so that the three-dimensional substrate adsorbs the metal ions and the acid and / or salt in the acid solution and / or salt solution; the acid solution comprises one or more of molybdic acid, phosphomolybdic acid, and dialkyldithioaminomethyl molybdenum acid; the salt solution comprises one or more of ammonium molybdate, ammonium thiomolybdate, and ammonium molybdenum nickel heteropoly acid; and the three-dimensional substrate is a three-dimensional carbon framework; removing the three-dimensional substrate after adsorption, and performing washing and drying treatment; performing heat treatment on the dried three-dimensional substrate under the protection of an inert gas, so that the adsorbed metal ions and the acid and / or salt react with the surface of the three-dimensional substrate in situ to generate a metal carbide layer on the surface of the three-dimensional substrate, thereby obtaining a current collector preliminary product; placing the current collector preliminary product in a reaction furnace, and introducing a carbon source gas to generate a carbon coating layer on the surface of the metal carbide layer through plasma-enhanced chemical vapor deposition.

3. An electrode characterized by: The lithium-ion-philic coating layer is formed on the surface of the three-dimensional substrate, and the three-dimensional substrate is a three-dimensional conductive framework.

4. A method of making an electrode, characterized by: The preparation method of the metal carbide layer comprises the following steps: using an acid solution containing metal ions and / or a salt solution and the surface of the three-dimensional substrate to generate the metal carbide layer on the surface of the three-dimensional substrate in situ. The acid solution comprises one or more of molybdic acid, phosphomolybdic acid, and dialkyldithioaminomethyl molybdenum acid; and the salt solution comprises one or more of ammonium molybdate, ammonium thiomolybdate, and ammonium molybdenum nickel heteropoly acid. The method comprises the following steps: functionalizing the surface of the three-dimensional substrate; immersing the functionalized three-dimensional substrate in an acid solution containing metal ions and / or a salt solution, and performing ultrasonic treatment, standing and adsorbing, so that the three-dimensional substrate adsorbs the metal ions and the acid and / or salt in the acid solution and / or salt solution; the acid solution comprises one or more of molybdic acid, phosphomolybdic acid, and dialkyldithioaminomethyl molybdenum acid; the salt solution comprises one or more of ammonium molybdate, ammonium thiomolybdate, and ammonium molybdenum nickel heteropoly acid; and the three-dimensional substrate is a three-dimensional carbon framework; removing the three-dimensional substrate after adsorption, and performing washing and drying treatment; performing heat treatment on the dried three-dimensional substrate under the protection of an inert gas, so that the adsorbed metal ions and the acid and / or salt react with the surface of the three-dimensional substrate in situ to generate a metal carbide layer on the surface of the three-dimensional substrate, thereby obtaining a current collector preliminary product; placing the current collector preliminary product in a reaction furnace, and introducing a carbon source gas to generate a carbon coating layer on the surface of the metal carbide layer through plasma-enhanced chemical vapor deposition. The lithium-ion-philic coating layer is formed on the surface of the three-dimensional substrate, and the three-dimensional substrate is a three-dimensional conductive framework. The preparation method of the metal carbide layer comprises the following steps: using an acid solution containing metal ions and / or a salt solution and the surface of the three-dimensional substrate to generate the metal carbide layer on the surface of the three-dimensional substrate in situ. The acid solution comprises one or more of molybdic acid, phosphomolybdic acid, and dialkyldithioaminomethyl molybdenum acid; and the salt solution comprises one or more of ammonium molybdate, ammonium thiomolybdate, and ammonium molybdenum nickel heteropoly acid. The method comprises the following steps: functionalizing the surface of the three-dimensional substrate; immersing the functionalized three-dimensional substrate in an acid solution containing metal ions and / or a salt solution, and performing ultrasonic treatment, standing and adsorbing, so that the three-dimensional substrate adsorbs the metal ions and the acid and / or salt in the acid solution and / or salt solution; the acid solution comprises one or more of molybdic acid, phosphomolybdic acid, and dialkyldithioaminomethyl molybdenum acid; the salt solution comprises one or more of ammonium molybdate, ammonium thiomolybdate, and ammonium molybdenum nickel heteropoly acid; and the three-dimensional substrate is a three-dimensional carbon framework; removing the three-dimensional substrate after adsorption, and performing washing and drying treatment; performing heat treatment on the dried three-dimensional substrate under the protection of an inert gas, so that the adsorbed metal ions and the acid and / or salt react with the surface of the three-dimensional substrate in situ to generate a metal carbide layer on the surface of the three-dimensional substrate, thereby obtaining a current collector preliminary product; placing the current collector preliminary product in a reaction furnace, and introducing a carbon source gas to generate a carbon coating layer on the surface of the metal carbide layer through plasma-enhanced chemical vapor deposition.

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