A lithium metal battery negative electrode composite and a method of making the same

Abstract

The present application belongs to the field of lithium metal battery, discloses a kind of lithium metal battery negative composite material and its preparation method, with foam nickel as substrate, mesoporous nanometer gold film is in situ grown on its surface by polymer micelle replacement reaction, then sulfur modification is carried out on the surface of gold film, and the composite material of sulfur-doped mesoporous nanometer gold film and foam nickel is prepared and used as negative material of lithium metal battery.The present application helps to realize dendrite-free lithium deposition / stripping process, makes lithium metal battery have high stability and long cycle life, and is a successful strategy to improve the electrochemical performance of lithium metal battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium metal battery technology, and relates to a lithium metal battery anode composite material and its preparation method, specifically to a lithium metal battery anode sulfur-doped mesoporous nano-gold film and foamed nickel composite material and its preparation method. Background Technology

[0002] With the rapid development of emerging industries such as smart communication devices and new energy vehicles, the anode materials for commercial lithium-ion batteries have become increasingly important due to their relatively low theoretical capacity (graphite's theoretical capacity is 372 mAh g). -1 This has severely hampered the development of the new energy industry. Lithium metal, due to its high theoretical capacity (3860 mAh g), has been significantly affected. -1 It has a low redox potential (-3.04V vs. standard hydrogen electrode) and the lowest mass density (0.53g cm⁻¹). -3 It is considered the most ideal negative electrode material.

[0003] However, the large-scale application of lithium metal batteries is hindered by several serious defects, such as severe volume changes during charging and discharging, fragile solid electrolyte interfaces, undirected dendrite growth that can puncture the separator, and the formation of dead lithium during deposition / stripping. These problems result in low coulombic efficiency, high electrode impedance, severe capacity loss, short lifespan, and safety hazards, thus limiting the application of lithium metal batteries.

[0004] To overcome these obstacles, researchers have developed various solutions, such as introducing three-dimensional host materials, constructing artificial solid electrode interfaces, and designing solid electrolytes. Among these, designing three-dimensional high specific surface area current collectors is an effective method to suppress lithium dendrite growth by addressing the problem of excessively high local current density. Scientists have extensively studied various current collectors, including graphene, metal foams, three-dimensional hollow carbon fibers, and three-dimensional graphitic carbon foams. Metal foams are well-suited as three-dimensional conductive substrates for lithium metal due to their low cost and good scalability. However, the random macropores and non-uniform lithium-ion transport on these foam metal skeletons easily lead to lithium dendrite formation and dead lithium problems. Therefore, they are considered low-quality three-dimensional porous current collectors for lithium metal batteries. In addition, the inherent lithium-repellency of nickel and copper surfaces increases the nucleation overpotential of lithium, which also leads to the non-directional growth of lithium dendrites. Summary of the Invention

[0005] This invention addresses the aforementioned problems by proposing a lithium metal battery anode composite material and its preparation method. Using nickel foam as a substrate, a mesoporous gold nanofilm is grown in situ on its surface through a polymer micelle displacement reaction. Then, sulfur modification is performed on the surface of the gold film to prepare a sulfur-doped mesoporous gold nanofilm and nickel foam composite material, which can be used as an anode material for lithium metal batteries.

[0006] This structure can modulate ion transport and adapt to the volume changes of the electrode during lithium deposition / stripping cycles, uniformly distribute the electric field on the electrode surface, reduce the overpotential of lithium during nucleation, and exhibit dendrite-free lithium deposition and stripping behavior.

[0007] The technical solution of the present invention is as follows:

[0008] A lithium metal battery anode composite material, which has a bilayer structure with nickel foam as the base layer and sulfur-doped mesoporous gold nanofilm as the surface layer.

[0009] A method for preparing a lithium metal battery anode composite material, specifically implemented according to the following steps:

[0010] Step 1: Clean the nickel foam substrate;

[0011] Step 2: Preparation of mesoporous gold film@nickel foam. Mesoporous gold nanofilms were grown in situ on the surface of the nickel foam via polymer micelle displacement reaction.

[0012] Step 3: Preparation of sulfur-doped mesoporous gold film@nickel foam, by modifying the surface of the mesoporous gold nanofilm with sulfur.

[0013] Furthermore, the specific process of step 1 is as follows: cut a piece of original nickel foam with an area of ​​4×4cm, sonicate it in acetone solution for 10-30min, sonicate the nickel foam in a 3mol / L hydrochloric acid solution for 10-30min, sonicate the nickel foam with hydrochloric acid in ultrapure water for 10-30min, and quickly transfer the ultrasonically cleaned nickel foam to a vacuum drying oven at 60℃ overnight.

[0014] Furthermore, step 2 specifically involves: adding 30-50 mg of [C8H8]... m -b-[C2H4O] n - Dissolve the product in 10-15 mL tetrahydrofuran solution under ultrasonic conditions. Add 5-10 mL ethanol and 5-10 mL HAuCl4 with a concentration of 10-35 mmol / L to the solution under atmospheric conditions. Immerse the cleaned and dried nickel foam substrate from step 1 in the solution and react for 5-30 min. After the reaction is complete, rinse the product three times each with ultrapure water and ethanol, and dry it at 60 °C for later use.

[0015] Furthermore, the specific process of step 3 is as follows: dissolve 70-90 mg of sublimed sulfur in 40 mL of ethylene glycol solution, immerse the mesoporous gold film@nickel foam prepared in step 2 in the solution, stir magnetically for 5 h at room temperature, rinse the sample with ultrapure water, and then vacuum dry at 60 °C for 5-10 h.

[0016] The present invention has the following beneficial effects:

[0017] (1) The composite material itself has a self-supporting mesoporous structure that can regulate ion transport and adapt to the volume changes of the electrode during lithium deposition / stripping cycles.

[0018] (2) The mesoporous gold film of the composite material in this invention can provide a large number of nucleophilic sites for lithium nucleation, uniformly guide the deposition of lithium, and inhibit the growth of lithium dendrites.

[0019] (3) The sulfur doping of the composite material in this invention can enable the lithium metal anode to form a more stable SEI film in situ, uniformly induce the stripping of lithium, and make the electrode almost return to its previous state after stripping. Only a uniform and flat SEI film remains on the electrode surface, which inhibits the generation of dead lithium.

[0020] (4) In this invention, sulfur-doped mesoporous nano-gold film and nickel foam composite material are used as negative electrode material, and lithium metal battery exhibits better electrochemical performance, and can maintain a longer cycle life and extremely high stability. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the sulfur-doped mesoporous gold nanofilm and nickel foam composite material of Example 1 of the present invention;

[0022] Figure 2 This is a microstructure diagram of the sulfur-doped mesoporous gold nanofilm and nickel foam composite material of Example 1 of the present invention;

[0023] Figure 3 This is an X-ray diffraction pattern of sulfur-doped mesoporous gold nanofilm (SMGF) in Example 1 of the present invention. Detailed Implementation

[0024] The present invention will now be described in detail with reference to specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described below. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0025] Example 1

[0026] A method for preparing a composite material of sulfur-doped mesoporous gold nanofilm and nickel foam for lithium metal battery anodes, specifically implemented according to the following steps:

[0027] Step 1: Cleaning the nickel foam substrate: Cut a piece of original nickel foam with an area of ​​4×4cm, sonicate it in acetone solution for 15min, then sonicate it in 3mol / L hydrochloric acid solution for 15min, and then sonicate it in ultrapure water for 15min. Quickly transfer the cleaned nickel foam to a vacuum drying oven at 60℃ overnight.

[0028] Step 2, Preparation of mesoporous gold film@nickel foam: 40 mg of [C8H8] m -b-[C2H4O] n - Dissolve the product in 12 mL of tetrahydrofuran solution under ultrasonic conditions. Add 6 mL of ethanol and 8 mL of 20 mmol / L HAuCl4 to the solution under ultrasonic conditions. Place the cleaned and dried nickel foam substrate from step 1 into the solution under atmospheric conditions and soak for 10 min. After the reaction is complete, rinse the product three times each with ultrapure water and ethanol, and dry it at 60 °C for later use.

[0029] Step 3: Preparation of sulfur-doped mesoporous gold film@nickel foam: Dissolve 80 mg of sublimed sulfur in 40 mL of ethylene glycol solution, immerse the mesoporous gold film@nickel foam prepared in step 2 in the solution, stir magnetically for 5 h at room temperature, and wash and vacuum dry the sample.

[0030] pass Figure 1 The structural diagram of the sulfur-doped mesoporous gold nanofilm and nickel foam composite material clearly shows that this material has a bilayer structure with nickel foam as the base layer and sulfur-doped mesoporous gold nanofilm as the surface layer.

[0031] pass Figure 2 The microstructure diagram of the sulfur-doped mesoporous gold nanofilm and nickel foam composite material shows that this material has a large number of mesoporous structures which are conducive to the transport of lithium ions, and the material has a large specific surface area, which can provide a large number of nucleation sites for lithium nucleation.

[0032] pass Figure 3 As can be seen in the X-ray diffraction pattern, all peaks in the XRD pattern of sulfur-doped mesoporous gold nanofilm (SMGF) correspond well to the gold crystal structure (Au JCPDS card no. 04-0784), confirming that gold was successfully grown on the substrate and that the sulfur layer can be modified on the gold surface without forming chemical bonds.

[0033] Example 2

[0034] A method for preparing a composite material of sulfur-doped mesoporous gold nanofilm and nickel foam for lithium metal battery anodes, specifically implemented according to the following steps:

[0035] Step 1: Cleaning the nickel foam substrate: Cut a piece of original nickel foam with an area of ​​4×4cm, sonicate it in acetone solution for 15min, then sonicate it in 3mol / L hydrochloric acid solution for 15min, and then sonicate it in ultrapure water for 15min. Quickly transfer the cleaned nickel foam to a vacuum drying oven at 60℃ overnight.

[0036] Step 2, Preparation of mesoporous gold film@nickel foam: 40 mg of [C8H8] m -b-[C2H4O]n - Dissolve the product in 12 mL of tetrahydrofuran solution under ultrasonic conditions. Add 6 mL of ethanol and 8 mL of HAuCl4 with a concentration of 35 mmol / L to the solution under ultrasonic conditions. Place the cleaned and dried nickel foam substrate from step 1 into the solution under atmospheric conditions and soak for 5 min. After the reaction is complete, rinse the product three times each with ultrapure water and ethanol, and dry it at 60 °C for later use.

[0037] Step 3: Preparation of sulfur-doped mesoporous gold film@nickel foam: Dissolve 90 mg of sublimed sulfur in 40 mL of ethylene glycol solution, immerse the mesoporous gold film@nickel foam prepared in step 2 in the solution, stir magnetically for 5 h at room temperature, and wash and vacuum dry the sample.

[0038] Example 3

[0039] A method for preparing a composite material of sulfur-doped mesoporous gold nanofilm and nickel foam for lithium metal battery anodes, specifically implemented according to the following steps:

[0040] Step 1: Cleaning the nickel foam substrate: Cut a piece of original nickel foam with an area of ​​4×4cm, sonicate it in acetone solution for 15min, then sonicate it in 3mol / L hydrochloric acid solution for 15min, and then sonicate it in ultrapure water for 15min. Quickly transfer the cleaned nickel foam to a vacuum drying oven at 60℃ overnight.

[0041] Step 2, Preparation of mesoporous gold film@nickel foam: 40 mg of [C8H8] m -b-[C2H4O] n - Dissolve the product in 12 mL of tetrahydrofuran solution under ultrasonic conditions. Add 6 mL of ethanol and 8 mL of 10 mmol / L HAuCl4 to the solution under ultrasonic conditions. Place the cleaned and dried nickel foam substrate from step 1 into the solution under atmospheric conditions and soak for 30 min. After the reaction is complete, rinse the product three times each with ultrapure water and ethanol, and dry it at 60 °C for later use.

[0042] Step 3: Preparation of sulfur-doped mesoporous gold film@nickel foam: Dissolve 70 mg of sublimed sulfur in 40 mL of ethylene glycol solution, immerse the mesoporous gold film@nickel foam prepared in step 2 in the solution, stir magnetically for 5 h at room temperature, and wash and vacuum dry the sample.

[0043] Example 4 Performance Test

[0044] The composite electrode maintains a high and stable coulombic efficiency after 170 cycles, indicating that a stable SEI layer can be formed on the electrode surface, which helps to stabilize the electrode / electrolyte interface. This suggests that lithium metal batteries using this composite material as the negative electrode have better cycle performance.

[0045] The composite electrode still exhibits high coulombic efficiency and capacity retention after 1000 cycles, further demonstrating that lithium metal batteries using this composite material as the negative electrode have excellent cycle stability and long cycle life.

[0046] If nickel foam is used directly as the anode material for lithium metal batteries, due to the lithium-phobicity and inhomogeneity of the nickel foam surface, lithium will nucleate unevenly and discontinuously on the nickel foam skeleton surface. The deposited lithium will develop into loose aggregates, and some lithium nuclei will gradually evolve into dendrites in the later stages of development. When using mesoporous gold film@nickel foam as the anode material for lithium metal batteries, its lithium affinity is lower than that of sulfur-doped mesoporous gold film@nickel foam composite material. As the deposition capacity increases, its lithium affinity gradually decreases, resulting in a rough and uneven lithium coating with a gradual increase in dendritic protrusions. Furthermore, while lithium can be stripped from both the top and root of the deposited lithium metal, when using the above two materials as anodes, lithium tends to be removed from the top surface of the deposited lithium rather than the root, leading to a significant amount of dead lithium during the stripping process in the first two materials. When sulfur-doped mesoporous gold film@nickel foam is used as the negative electrode material for lithium metal batteries, the electrode exhibits a very uniform morphology throughout the lithium deposition process. This indicates that the mesoporous lithium-loving composite material can not only control uniform lithium nucleation / growth and suppress dendrite formation during lithium deposition, but also induce uniform lithium stripping and avoid the formation of dead lithium.

[0047] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a lithium metal battery anode composite material, characterized in that, Includes the following steps: Step 1: Clean the nickel foam substrate; cut a piece of original nickel foam with an area of ​​4×4 cm, sonicate it in acetone solution for 10-30 min, then sonicate it in 3 mol / L hydrochloric acid solution for 10-30 min, then sonicate it in ultrapure water for 10-30 min, and then quickly transfer the cleaned nickel foam to a vacuum drying oven at 60 ℃ overnight. Step 2: Preparation of mesoporous gold film@nickel foam. A mesoporous gold nanofilm was grown in situ on its surface via a polymer micelle displacement reaction; 30-50 mg of -[C8H8] was then added. m -b-[C2H4O] n - Dissolve the product in 10-15 mL tetrahydrofuran solution under ultrasonic conditions. Add 5-10 mL ethanol and 5-10 mL HAuCl4 with a concentration of 10-35 mmol / L to the solution under ultrasonic conditions. Place the cleaned and dried nickel foam substrate from step 1 into the solution under atmospheric conditions and soak for 5-30 min. After the reaction is complete, rinse the product with ultrapure water and ethanol 3 times each and dry it at 60 °C for later use. Step 3: Preparation of sulfur-doped mesoporous gold film@nickel foam. Sulfur modification is performed on the surface of the mesoporous gold nanofilm. 70-90 mg of sublimed sulfur is dissolved in 40 mL of ethylene glycol solution. The mesoporous gold film@nickel foam prepared in step 2 is immersed in the solution and magnetically stirred at room temperature for 5 h. After rinsing the sample with ultrapure water, it is vacuum dried at 60 ℃ for 5-10 h. The prepared material is a bilayer structure with nickel foam as the base layer and sulfur-doped mesoporous gold nanofilm as the surface layer.

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