CN116779877A - Preparation method and application of molybdenum nitride-coated copper nanowire/foam copper current collector with lithiophilic gradient - Google Patents

Abstract

A preparation method and application of a molybdenum nitride coated copper nanowire/foam copper current collector with a lithium-philic gradient relate to a preparation method and application of a foam copper current collector. The invention aims to solve the problems that lithium grows uncontrollably on the smooth surfaces of the existing foam copper serving as a three-dimensional current collector, the lithium affinity of copper is poor, the nucleation barrier on the surface of the lithium is high, the uniform nucleation of the lithium is further limited, and the growth of lithium dendrites is accelerated. The method comprises the following steps: 1. preparing a copper nanowire/foam copper composite material; 2. preparing MoN@CW@CF; use of a molybdenum nitride coated copper nanowire/copper foam current collector with a lithium-philic gradient on a lithium metal battery anode. The invention can obtain the molybdenum nitride coated copper nanowire/foam copper current collector with a lithium-philic gradient.

Description

A molybdenum nitride-coated copper nanowire/foam copper current collector with a lithiophilic gradient Preparation methods and applications

Technical field

The invention relates to a preparation method and application of copper foam current collector.

Background technique

The global energy crisis and unprecedented power energy consumption have prompted the development of sustainable power energy storage technologies, and high-density rechargeable batteries have attracted increasing attention. Among all available solid anode materials, lithium metal is widely considered to be one of the most ideal anodes due to its ultra-high theoretical specific capacity (3860mAh g ^-1 ) and lowest reduction potential (-3.04V vs standard hydrogen electrode) . However, the practical application of lithium metal anodes still faces some challenges. In particular, the uneven deposition of lithium, the infinite volume change of lithium during plating/stripping, and the formation of fragile solid-electrolyte interface (SEI) layers. All of these can lead to the growth of lithium dendrites and the formation of "dead lithium," leading to serious safety issues in lithium metal batteries. In addition, the irreversible consumption of lithium and electrolyte also results in low Coulombic efficiency and short cycle life. In recent years, great efforts have been made to solve the above problems of lithium metal anodes. Constructing lithium metal anodes with three-dimensional bodies is an effective strategy to reduce local current density and volume effects during cycling. Common three-dimensional main conductive nanostructure current collectors, such as metal foam, copper nanowires, lithium-containing alloys, layered reduced graphene oxide, carbon nanospheres, carbon nanofibers, biochar skeletons, etc., are mostly concentrated on the plane parallel to the electrode The lithium deposition is homogenized, while the vertical lithium ion concentration gradient present during cycling is usually ignored. Especially in three-dimensional bodies, the vertical lithium ion concentration has an adverse effect on uniform lithium deposition in the vertical direction. The lithium ions on the surface of the body generate a higher lithium ion flux in the electrolyte, which will weaken the effect of the three-dimensional structure and lead to the covering deposition of lithium and lithium dendrites. The development of more effective and general strategies to overcome the non-uniform lithium deposition in the vertical direction caused by lithium ion concentration gradient is crucial for the application of three-dimensional bodies of lithium metal batteries.

Compared with other three-dimensional current collectors, traditional copper foam (CF) is the preferred material. The primary copper foam frame can provide abundant micron-sized pores, which can accommodate a large amount of lithium metal and reduce volume expansion. However, the relatively smooth skeleton surface and low surface area of CF cannot provide good electrical contact for circulating lithium, resulting in uncontrollable growth of lithium on these smooth surfaces. Properly designing the secondary structure of copper foam can release volume expansion and improve lithium utilization. In addition, copper has poor lithiophilicity, resulting in a high nucleation barrier on the lithium surface, further limiting the uniform nucleation of lithium and accelerating the growth of lithium dendrites.

Contents of the invention

The purpose of this invention is to solve the problem of uncontrollable growth of lithium on these smooth surfaces in the existing copper foam as a three-dimensional current collector. Copper has poor lithiophilicity, resulting in a higher nucleation barrier on the lithium surface, further limiting the The uniform nucleation of lithium accelerates the growth of lithium dendrites, and a preparation method and application of molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient are provided.

A method for preparing molybdenum nitride-coated copper nanowire/foam copper current collector with a lithiophilic gradient, which is specifically completed according to the following steps:

1. Preparation of copper nanowire/copper foam composite materials:

① Use foamed copper as the working electrode, use platinum sheet as the counter electrode, use potassium hydroxide solution as the electrolyte, conduct electrodeposition at 5mAcm ^-2 ~ 20mA cm ^-2 , and grow copper hydroxide nanowires on the surface of the copper foam. Obtain the sample; use deionized water to clean the sample, and then place it in a vacuum oven to dry to obtain a dried sample;

②. Place the dried sample in a plasma reaction chamber at 180°C to 250°C, and pass hydrogen into the plasma reaction chamber to keep the pressure in the reaction chamber at 10Pa to 30Pa during the glow discharge process, and then Continue processing for 3 minutes to 10 minutes at a radio frequency plasma power of 200W to 250W, and lower the temperature to room temperature to obtain a copper nanowire/copper foam composite material;

2. Preparation of MoN@CW@CF:

①. Place the copper nanowire/copper foam composite material in the ALD reaction chamber, evacuate the chamber and keep the pressure in the reaction chamber at 0.5Torr, raise the temperature to 200℃~220℃, and mix molybdenum hexacarbonyl, ozone and water vapor According to the cycle setting program, it is introduced into the reaction chamber for cyclic deposition, so that molybdenum oxide grows layer by layer on the surface of the copper nanowire/copper foam composite material, and the molybdenum oxide/copper nanowire/copper foam composite material is obtained;

②. Place the molybdenum oxide/copper nanowire/copper foam composite material in a plasma reaction chamber at 350°C to 450°C, and pass ammonia gas into the plasma reaction chamber to increase the pressure of the reaction chamber during the glow discharge process. Keep it at 10Pa ~ 30Pa, and then continue processing at a radio frequency plasma power of 200W ~ 250W for 2min ~ 5min. The temperature drops to room temperature to obtain a molybdenum nitride-coated copper nanowire/foam copper current collector with a lithiophilic gradient.

Application of molybdenum nitride-coated copper nanowire/copper foam current collector with lithiophilic gradient on lithium metal battery anode.

Advantages of the invention:

The invention provides a preparation method of a molybdenum nitride layer-coated copper nanowire composite copper foam (MoN@CW@CF) three-dimensional anode current collector and its application on the anode of a lithium metal battery; the invention uses simple electrochemistry The deposition, dehydration and reduction processes grow a copper nanowire structure on the surface of the copper foam; the copper nanofibers provide a large number of charge centers and electrochemical sites, which can evenly distribute the surface charge of the copper foam framework; through atomic layer deposition (ALD) and ammonia Gas plasma nitridation deposits a uniform molybdenum nitride layer on the surface of copper nanowires, which provides abundant nucleation sites for lithium plating/stripping; since ALD only deposits one side of the substrate, vertical direction is achieved on the copper foam substrate. Gradient distribution of molybdenum oxide, the molybdenum oxide layer is rapidly nitrided into a lithiophilic molybdenum nitride layer through ammonia plasma treatment; the uniform ultra-thin lithiophilic layer and sub-micron nanowire layer are both current collectors to inhibit lithium trees The formation of lithium and "dead lithium" plays a vital role; at the same time, the copper foam structure has good mechanical properties, ensuring the high structural stability of the anode during rapid repeated plating and stripping processes.

Advantages of the invention:

The present invention tests the electrical properties of the obtained molybdenum nitride-coated copper nanowire/foam copper anode material. The results show that under a current density of 1mA cm ^-2 and a surface capacity of 1mAh cm ^-2 , the MoN@CW@CF assembly The average Coulombic efficiency of the half-cell in 240 cycles is as high as 98%, and the assembled symmetrical battery can cycle stably for 1200 hours, which shows that the lithium metal battery anode material provided by the present invention has excellent lithium plating/stripping stability; when used with LiFePO ₄ cathode When combined, the MoN@CW@CF electrode showed a high discharge specific capacity of 133.8mAh g ^-1 and a high capacity retention rate of 98.6% after 250 cycles, which shows that the lithium metal battery anode material provided by the present invention has a high cycle performance. life.

Description of drawings

Figure 1 is a schematic flow chart of the molybdenum nitride-coated copper nanowire/foam copper current collector with a lithiophilic gradient prepared in Example 1;

Figure 2 is a picture of the actual sample at different experimental stages in Example 1. In the figure, a is CF, b is CW@CF, c is the surface layer of MoN@CW@CF, and d is the bottom layer of MoN@CW@CF;

Figure 3 shows the scanning electron microscope image of the sample. In the figure, a and b are CF, c and d are CW@CF, and e and f are MoN@CW@CF;

Figure 4 shows the XPS spectrum. In the figure, a is the XPS spectrum of Mo3d, and b is the XPS spectrum of N1s;

Figure 5 is a scanning electron microscope image of the electrode obtained after lithium deposition in Example 2. In the figure, a is a Li@CF electrode, b is a Li@CW@CF electrode, and c is a Li@MoN@CW@CF electrode;

Figure 6 is a Coulombic efficiency diagram of the MoN@CW@CF assembled half-cell prepared in Example 1 under 1 mAcm ^-2 in Example 3;

Figure 7 is a cycle stability diagram of the symmetrical battery assembled using MoN@CW@CF prepared in Example 1 in Example 4;

Figure 8 is a diagram of the Coulombic efficiency and discharge capacity of the Li@MoN@CW@CF||LFP full cell assembled using the Li@MoN@CW@CF electrode prepared in Example 2 in Example 5.

Detailed ways

Specific Embodiment 1: This embodiment is a method for preparing molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient. Specifically, it is completed according to the following steps:

1. Preparation of copper nanowire/copper foam composite materials:

① Use foamed copper as the working electrode, use platinum sheet as the counter electrode, use potassium hydroxide solution as the electrolyte, conduct electrodeposition at 5mAcm ^-2 ~ 20mA cm ^-2 , and grow copper hydroxide nanowires on the surface of the copper foam. Obtain the sample; use deionized water to clean the sample, and then place it in a vacuum oven to dry to obtain a dried sample;

②. Place the dried sample in a plasma reaction chamber at 180°C to 250°C, and pass hydrogen into the plasma reaction chamber to keep the pressure in the reaction chamber at 10Pa to 30Pa during the glow discharge process, and then Continue processing for 3 minutes to 10 minutes at a radio frequency plasma power of 200W to 250W, and lower the temperature to room temperature to obtain a copper nanowire/copper foam composite material;

2. Preparation of MoN@CW@CF:

①. Place the copper nanowire/copper foam composite material in the ALD reaction chamber, evacuate the chamber and keep the pressure in the reaction chamber at 0.5Torr, raise the temperature to 200℃~220℃, and mix molybdenum hexacarbonyl, ozone and water vapor According to the cycle setting program, it is introduced into the reaction chamber for cyclic deposition, so that molybdenum oxide grows layer by layer on the surface of the copper nanowire/copper foam composite material, and the molybdenum oxide/copper nanowire/copper foam composite material is obtained;

②. Place the molybdenum oxide/copper nanowire/copper foam composite material in a plasma reaction chamber at 350°C to 450°C, and pass ammonia gas into the plasma reaction chamber to increase the pressure of the reaction chamber during the glow discharge process. Keep it at 10Pa ~ 30Pa, and then continue processing at a radio frequency plasma power of 200W ~ 250W for 2min ~ 5min. The temperature drops to room temperature to obtain a molybdenum nitride-coated copper nanowire/foam copper current collector with a lithiophilic gradient.

Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the thickness of the copper foam described in step 1① is 300 μm to 2 mm. Other steps are the same as the first embodiment.

Specific Embodiment 3: The difference between this embodiment and Specific Embodiment 1 or 2 is that the concentration of the potassium hydroxide solution described in step 1① is 1 mol/L to 2 mol/L. Other steps are the same as the first or second embodiment.

Specific Embodiment 4: The difference between this embodiment and one of Specific Embodiments 1 to 3 is that the electrodeposition time described in step 1① is 5 min to 20 min. Other steps are the same as the specific embodiments one to three.

Specific Embodiment 5: The difference between this embodiment and one of Specific Embodiments 1 to 4 is that the drying temperature described in step 1① is 60°C to 100°C, and the drying time is 6h to 12h. Other steps are the same as the specific embodiments one to four.

Specific Embodiment 6: The difference between this implementation mode and any one of Specific Embodiments 1 to 5 is that the flow rate of hydrogen described in step 1② is 10 sccm to 20 sccm. Other steps are the same as the specific embodiments 1 to 5.

Specific Embodiment 7: The difference between this embodiment and one of Specific Embodiments 1 to 6 is that the number of cyclic depositions described in step 2① is 150 to 300 cycles. Other steps are the same as the specific embodiments one to six.

Specific Embodiment 8: The difference between this embodiment and one of Specific Embodiments 1 to 7 is that the cycle setting procedure is: (1), passing in molybdenum hexacarbonyl for 0.3 s; (2), purging with nitrogen for 60 s. ; (3), introduce water vapor for 5s; (4), purge with nitrogen for 5s; (5), purge with ozone for 0.03s; (6), purge with nitrogen for 50s. Other steps are the same as the specific embodiments one to seven.

Specific Embodiment 9: The difference between this embodiment and one of Specific Embodiments 1 to 8 is that the flow rate of ammonia gas described in step 2② is 10 sccm to 20 sccm. Other steps are the same as the specific embodiments 1 to 8.

Specific Embodiment 10: This embodiment is the application of molybdenum nitride-coated copper nanowires/copper foam current collectors with lithiophilic gradients on lithium metal battery anodes.

The following examples are used to verify the beneficial effects of the present invention:

Example 1: A method for preparing molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient. Specifically, the steps are as follows:

1. Preparation of copper nanowire/copper foam composite materials:

① Use copper foam (CF) as the working electrode, platinum sheet as the counter electrode, potassium hydroxide solution with a concentration of 1mol/L as the electrolyte, conduct electrodeposition at 10mA cm ^-2 for 20 minutes, and grow on the surface of the copper foam. Copper hydroxide nanowires to obtain a sample; use deionized water to clean the sample, and then place it in a vacuum oven at a temperature of 60°C to dry for 6 hours to obtain a dried sample;

②. Place the dried sample in a plasma reaction chamber at 200°C, pass 15 sccm hydrogen gas into the plasma reaction chamber, so that the pressure in the reaction chamber is maintained at 10 Pa during the glow discharge process, and then in the radio frequency plasma The power is 250W and the process is continued for 5 minutes, and the temperature is lowered to room temperature to obtain copper nanowire/copper foam composite material (CW@CF);

2. Preparation of MoN@CW@CF:

①. Place the copper nanowire/copper foam composite material in the ALD reaction chamber, evacuate the chamber and keep the pressure in the reaction chamber at 0.5Torr, raise the temperature to 220°C, and set molybdenum hexacarbonyl, ozone and water vapor according to the cycle A certain program is introduced into the reaction chamber for cyclic deposition, so that molybdenum oxide grows layer by layer on the surface of the copper nanowire/copper foam composite material, and the molybdenum oxide/copper nanowire/copper foam composite material is obtained;

The number of cyclic depositions described in step 2① is 300 cycles; the cycle setting program is: (1), pass in molybdenum hexacarbonyl for 0.3s; (2), purge nitrogen for 60s; (3) , introduce water vapor for 5s; (4), purge with nitrogen for 5s; (5), purge with ozone for 0.03s; (6), purge with nitrogen for 50s;

②. Place the molybdenum oxide/copper nanowire/copper foam composite material in a plasma reaction chamber at 400°C. Pour 15 sccm ammonia into the plasma reaction chamber. The pressure in the reaction chamber is maintained at 10 Pa during the glow discharge process. , and then continued processing for 2 minutes at a radio frequency plasma power of 250W, and the temperature dropped to room temperature, and a molybdenum nitride-coated copper nanowire/copper foam current collector (MoN@CW@CF) with a lithiophilic gradient was obtained.

In this embodiment, three-dimensional porous copper foam is used as a template to prepare copper hydroxide nanowires through electrochemical deposition. The obtained nanowires are then dehydrated and reduced to obtain copper nanowires, forming a dense secondary structure on the surface of the copper foam; and then through ALD Molybdenum oxide and ammonia plasma are nitrided to obtain a uniform molybdenum nitride layer. The side with the lithiophilic molybdenum nitride layer is used as the bottom layer of the electrode sheet to construct a three-dimensional main structure with a gradient in the vertical direction. See the schematic diagram of the process. As shown in Figure 1.

Figure 2 is a picture of the actual sample at different experimental stages in Example 1. In the figure, a is CF, b is CW@CF, c is the surface layer of MoN@CW@CF, and d is the bottom layer of MoN@CW@CF;

It can be seen from Figure 2 that copper foam (CF) is golden (Figure 2a), nanowire/copper foam composite (CW@CF) is dark red (Figure 2b), and the top layer of MoN@CW@CF has no deposited oxidation. The color of the molybdenum copper nanowires did not change and was still dark red (Figure 2c). The bottom layer of MoN@CW@CF is brown-black due to the presence of the molybdenum nitride layer (Figure 2d).

Figure 3 shows the scanning electron microscope image of the sample. In the figure, a and b are CF, c and d are CW@CF, and e and f are MoN@CW@CF;

Figure 3 (a, b) shows the scanning electron microscope images of copper foam (CF) at different magnifications. It can be seen that the surface is exposed and smooth; Figure 3 (c, d) shows the difference of copper nanowires/copper foam (CW@CF). Magnified scanning electron microscope image shows dense nanowires growing on the surface of smooth copper foam. These nanowires are connected to each other, forming a secondary structure of the current collector and increasing the specific surface area of the current collector. The diameter of the copper nanowires is approximately 100nm. Figure 3 (e, f) shows the scanning electron microscope images of molybdenum nitride/copper nanowires/copper foam (MoN@CW@CF) at different magnifications. It can be seen that the structure is still nanowire-shaped, but the diameter of the nanowire has increased to Around 300nm, indicating that there is a deposition layer on the surface.

Figure 4 shows the XPS spectrum. In the figure, a is the XPS spectrum of Mo3d, and b is the XPS spectrum of N1s;

It can be seen from Figure 4a that the molybdenum in the sample is Mo ³⁺ . Combined with the existence of the N-Mo bond in Figure 4b, it can be proved that the invention successfully prepared a lithiophilic molybdenum nitride layer.

Example 2: Li@MoN@CW@CF electrode is completed according to the following steps:

MoN@CW@CF prepared in Example 1 was used as the positive electrode, one side of the copper nanowire/copper foam was close to the separator, and the lithium sheet was used as the negative electrode to assemble a button cell. The electrolyte was 1M LITFSI dissolved in DOL/DME (v:v=1 :1)+2% LiNO ₃ , 40 microliters each on the positive and negative electrode surfaces. Deposit for 20h at a current density of 0.25mAcm ^-2 , and deposit lithium with a capacity of 5mAhcm ^-2 on the MoN@CW@CF electrode. After disassembling the battery, the Li@MoN@CW@CF electrode is obtained; the 1M LITFSI is dissolved in DOL/DME (v:v=1:1)+2% LiNO ₃ is LITFSI and LiNO ₃ dissolved into the mixture of DOL and DME to obtain an electrolyte, where the volume ratio of DOL to DME in the mixture of DOL and DME is The ratio is 1:1, the concentration of LITFSI in the electrolyte is 1 mol/L, and the mass fraction of LiNO ₃ is 2%.

Follow the same method as above, use CF as the positive electrode, and deposit lithium ions on the surface of CF to obtain a Li@CF electrode;

According to the same method as above, CW@CF is used as the positive electrode, and lithium ions are deposited on the surface of CW@CF to obtain a Li@CW@CF electrode;

Figure 5 is a scanning electron microscope image of the electrode obtained after lithium deposition in Example 2. In the figure, a is a Li@CF electrode, b is a Li@CW@CF electrode, and c is a Li@MoN@CW@CF electrode;

It can be seen from Figure 5 a and b that dendritic lithium grows in large quantities in the hole structure of the copper foam, and the deposited lithium only covers the upper surface of the skeleton. However, the current collector prepared by the present invention does not produce dendritic lithium, and the copper foam structure still exists, indicating that lithium ions are deposited inside the copper foam.

Example 3: Assembling a half-cell using MoN@CW@CF prepared in Example 1 is completed according to the following steps:

MoN@CW@CF prepared in Example 1 was used as the positive electrode, one side of the copper nanowire/copper foam was close to the separator, and the lithium sheet was used as the negative electrode to assemble a button cell. The electrolyte was 1M LITFSI dissolved in DOL/DME (v:v=1 :1)+2% LiNO ₃ , 40 microliters each on the positive and negative electrode surfaces. The half-cell test was performed at a current density of 1mA cm ^-2 and an area capacity of 1mAh cm ^-2 ; the 1MLITFSI dissolved in DOL/DME (v:v=1:1)+2% LiNO ₃ is LITFSI and LiNO ₃ Dissolve into the mixture of DOL and DME to obtain an electrolyte, in which the volume ratio of DOL to DME in the mixture of DOL and DME is 1:1, the concentration of LITFSI in the electrolyte is 1mol/L, and the mass fraction of LiNO ₃ is 2%.

Figure 6 is a Coulombic efficiency diagram of the MoN@CW@CF assembled half-cell prepared in Example 1 at 1 mA cm ^-2 in Example 3;

Figure 6 shows that the half-cell assembled using MoN@CW@CF prepared in Example 1 can maintain greater than 98% in 240 cycles at a current density of 1mAh cm ^-2 and a plating capacity of 1mAh cm ^-2 Average Coulomb efficiency. This indicates that MoN@CW@CF has good reversibility and high lithium utilization.

Symmetrical cells were assembled to further investigate the reversibility of the prepared electrodes.

Example 4: The symmetrical battery assembled using the MoN@CW@CF prepared in Example 1 was completed according to the following steps:

MoN@CW@CF prepared in Example 1 was used as the positive electrode, one side of the copper nanowire/copper foam was close to the separator, and the lithium sheet was used as the negative electrode to assemble a button cell. The electrolyte was 1M LITFSI dissolved in DOL/DME (v:v=1 :1)+2% LiNO ₃ , 40 microliters each on the positive and negative electrode surfaces. After depositing lithium with a capacity of 5mAhcm ^-2 on the MoN@CW@CF electrode for 20h at a current density of 0.25mA cm ^-2 , symmetry was performed at a current density of 1mA cm ^-2 and an areal capacity of 1mAh cm ^-2 Battery test; the 1MLITFSI is dissolved in DOL/DME (v:v=1:1)+2% LiNO ₃ is LITFSI and LiNO ₃ is dissolved into a mixture of DOL and DME to obtain an electrolyte, in which the ratio of DOL and DME is The volume ratio of DOL to DME in the mixed solution is 1:1, the concentration of LITFSI in the electrolyte is 1 mol/L, and the mass fraction of LiNO ₃ is 2%.

Figure 7 is a cycle stability diagram of the symmetrical battery assembled using MoN@CW@CF prepared in Example 1 in Example 4;

Figure 7 shows the cycle stability measured at a current density of 1 mA cm ^-2 for the symmetrical battery assembled using MoN@CW@CF prepared in Example 1. The Li/MoN@CW@CF electrode can work for more than 1200 hours. In addition, the voltage The hysteresis (VH, the gap between lithium plating voltage and stripping voltage) is only 17mV, indicating that the anode current collector prepared by the present invention can effectively inhibit the reversible deposition of lithium and inhibit the growth of lithium dendrites, thereby improving cycle stability. sex.

Li@MoN@CW@CF was paired with commercial LiFePO ₄ (LFP) to study the electrochemical performance of the full cell. The thickness of the LFP electrode is approximately 70 μm, and the mass loading of the active material is approximately 4 mg cm ⁻² .

Example 5: A Li@MoN@CW@CF||LFP full battery assembled using the Li@MoN@CW@CF electrode prepared in Example 2 was completed according to the following steps:

Use the Li@MoN@CW@CF prepared in Example 2 as the negative electrode, with the copper nanowire/copper foam side close to the separator, and LiFePO ₄ (LFP) as the positive electrode to assemble a button cell. The electrolyte is 1M LIPF ₆ dissolved in EC/DEC. /DMC (v:v:v=1:1:1)+5% FEC, 50 microliters each on the positive and negative electrode surfaces. Full battery charge and discharge tests were performed at a current density of 1C.

The 1M LIPF ₆ is dissolved in EC/DEC/DMC (v:v:v=1:1:1)+5% FEC. LIPF ₆ and FEC are dissolved into a mixture of EC, DEC and DMC to obtain an electrolyte. , wherein the volume ratio of EC, DEC and DMC in the mixture of EC, DEC and DMC is 1:1:1; the concentration of LIPF ₆ in the electrolyte is 1mol/L, and the mass fraction of FEC is 5%;

Figure 8 is a diagram of the Coulombic efficiency and discharge capacity of the Li@MoN@CW@CF||LFP full cell assembled using the Li@MoN@CW@CF electrode prepared in Example 2 in Example 5;

It can be seen from Figure 8 that the Li@MoN@CW@CF||LFP full cell has an initial discharge capacity of 135.7mAh g ^-1 and a high capacity retention rate of 98.6% at 1C. These results show that the lithium metal battery anode material provided by the present invention can provide good discharge specific capacity and cycle life.

Claims (10)

1. A method for preparing molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient, characterized in that the preparation method is specifically completed according to the following steps: 1. Preparation of copper nanowire/copper foam composite materials: ① Use foamed copper as the working electrode, use platinum sheet as the counter electrode, use potassium hydroxide solution as the electrolyte, conduct electrodeposition at 5mA cm ^-2 ~ 20mA cm ^-2 , and grow copper hydroxide nanowires on the surface of the copper foam. , obtain the sample; use deionized water to clean the sample, and then place it in a vacuum oven to dry to obtain the dried sample; ②. Place the dried sample in a plasma reaction chamber at 180°C to 250°C, and pass hydrogen into the plasma reaction chamber to keep the pressure in the reaction chamber at 10Pa to 30Pa during the glow discharge process, and then Continue processing for 3 minutes to 10 minutes at a radio frequency plasma power of 200W to 250W, and lower the temperature to room temperature to obtain a copper nanowire/copper foam composite material; 2. Preparation of MoN@CW@CF: ①. Place the copper nanowire/copper foam composite material in the ALD reaction chamber, evacuate the chamber and keep the pressure in the reaction chamber at 0.5Torr, raise the temperature to 200℃~220℃, and mix molybdenum hexacarbonyl, ozone and water vapor According to the cycle setting program, it is introduced into the reaction chamber for cyclic deposition, so that molybdenum oxide grows layer by layer on the surface of the copper nanowire/copper foam composite material, and the molybdenum oxide/copper nanowire/copper foam composite material is obtained; ②. Place the obtained molybdenum oxide/copper nanowire/copper foam composite material in a plasma reaction chamber at 350°C to 450°C, and pass ammonia gas into the plasma reaction chamber to cause the pressure in the reaction chamber to increase during glow discharge. During the process, the temperature is maintained at 10Pa ~ 30Pa, and then the radio frequency plasma power is 200W ~ 250W for 2min ~ 5min, and the temperature is reduced to room temperature to obtain molybdenum nitride-coated copper nanowires/foam copper current collectors with a lithiophilic gradient. . 2. A method for preparing molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient according to claim 1, characterized in that the thickness of the copper foam described in step 1① is 300 μm～ 2mm. 3. The preparation method of a molybdenum nitride-coated copper nanowire/foam copper current collector with a lithiophilic gradient according to claim 1, characterized in that the concentration of the potassium hydroxide solution described in step 1① is 1mol/L～2mol/L. 4. A method for preparing molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient according to claim 1, characterized in that the electrodeposition time described in step 1① is 5 min～ 20min. 5. A method for preparing molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient according to claim 1, characterized in that the drying temperature described in step 1① is 60°C. ~100℃, drying time is 6h~12h. 6. A method for preparing molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient according to claim 1, characterized in that the flow rate of hydrogen described in step 1② is 10 sccm～20 sccm . 7. A method for preparing molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient according to claim 1, characterized in that the number of cyclic depositions described in step 2① is 150 times. ~300 cycles. 8. A method for preparing molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient according to claim 1 or 7, characterized in that the cycle setting program is: (1 ), pass in molybdenum hexacarbonyl for 0.3s; (2), purge with nitrogen for 60s; (3), pass in water vapor for 5s; (4), purge with nitrogen for 5s; (5), pass in ozone for 0.03s; (6) , nitrogen purge for 50s. 9. A method for preparing molybdenum nitride-coated copper nanowires/copper foam current collectors with a lithiophilic gradient according to claim 1, characterized in that the flow rate of ammonia gas described in step 2② is 10 sccm～ 20 sccm. 10. Application of a molybdenum nitride-coated copper nanowire/foam copper current collector with a lithiophilic gradient prepared by the preparation method of claim 1, characterized in that a molybdenum nitride coating with a lithiophilic gradient Application of copper-coated nanowires/copper foam current collectors on lithium metal battery anodes.