Lithium metal battery and preparation method thereof

Abstract

The invention relates to a lithium metal battery and a preparation method thereof. The lithium metal battery comprises a negative current collector and an electrolyte, the negative current collector comprises a carrier and a modified coating arranged on at least one side surface of the carrier; a nanowire array is arranged on the surface of the carrier; the modified coating comprises a bottom layer and a surface layer which are stacked, the bottom layer comprises a nucleation accelerant and a reinforcing agent, and the surface layer comprises an interface passivator and a structure stabilizer; and the electrolyte comprises a lithium supplement agent. According to the scheme provided by the invention, the growth of lithium dendrites in the battery can be inhibited, so that the battery shows excellent first coulombic efficiency and cycle performance.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to lithium metal batteries and their preparation methods. Background Technology

[0002] Lithium-ion batteries are widely used in 3C digital products, power tools, aerospace, energy storage, and electric vehicles due to their advantages such as high specific energy, no memory effect, and long cycle life. The rapid development of electronic information technology and consumer products has placed higher demands on the electrochemical performance of lithium-ion batteries.

[0003] In lithium metal batteries without negative electrode active materials (hereinafter referred to as negative electrode-free lithium metal batteries), the elimination of traditional negative electrode active materials in the negative electrode sheet gives them significant advantages in terms of improved energy density and reduced manufacturing costs, making them one of the core development directions for next-generation lithium-ion batteries. However, negative electrode-free lithium metal batteries in related technologies still face two major bottlenecks: First, uneven lithium deposition on the surface of the negative electrode current collector (such as copper foil) can easily lead to lithium dendrite growth, which can puncture the separator and cause a short circuit in the battery. At the same time, it increases the probability of electrolyte side reactions, resulting in the generation of "dead lithium" and a decrease in battery cycle life. Second, during the first charge, lithium ions extracted from the positive electrode need to complete nucleation and deposition on the surface of the negative electrode current collector. During this process, electrolyte decomposition and irreversible formation of the SEI film can lead to lithium ion loss, causing the battery's initial coulombic efficiency to be generally below 70%, which seriously restricts the actual energy output and application value of the battery.

[0004] Therefore, there is an urgent need to develop a lithium metal battery that can effectively suppress lithium dendrites and has high initial coulombic efficiency and excellent cycle performance. Summary of the Invention

[0005] To address or partially address the problems existing in related technologies, this application provides a lithium metal battery and its preparation method, which can suppress the growth of lithium dendrites in the battery, enabling the battery to exhibit excellent first coulombic efficiency and cycle performance.

[0006] The first aspect of this application provides a lithium metal battery, comprising a positive electrode, a separator, a negative electrode current collector, and an electrolyte; the negative electrode current collector comprises a carrier and a modified coating disposed on at least one side surface of the carrier; The surface of the carrier has a nanowire array; The modified coating comprises a bottom layer and a top layer stacked together. The bottom layer comprises a nucleation promoter and a reinforcing agent, and the top layer comprises an interface passivator and a structure stabilizer. The electrolyte includes a lithium supplement.

[0007] The lithium metal battery as described in the first aspect, wherein the nanowires in the nanowire array have a diameter of 50 nm to 200 nm and a length of 1 μm to 5 μm.

[0008] The lithium metal battery as described in the first aspect, wherein the nucleation promoter includes at least one of lithium fluoride, lithium nitride and lithium oxide; And / or, the reinforcing agent includes at least one of alumina, magnesium oxide and zirconium oxide; And / or, the interface passivating agent includes at least one of lithium carbonate, lithium metaphosphate, and lithium sulfate; And / or, the structural stabilizer includes at least one of titanium oxide, cerium oxide, and aluminum oxide.

[0009] The lithium metal battery as described in the first aspect, wherein the mass ratio of the nucleation promoter to the reinforcing agent is (3~5):1; And / or, the mass ratio of the interface passivating agent to the structure stabilizer is (2~4):1.

[0010] As described in the first aspect, in a lithium metal battery, the thickness of the modified coating is 13nm~22nm; wherein: The thickness of the bottom layer is 5nm to 10nm; and / or the thickness of the top layer is 8nm to 12nm.

[0011] The lithium metal battery as described in the first aspect, wherein the ionic conductivity of the SEI film of the lithium metal battery is greater than or equal to 5 × 10⁻⁶. -6 S / cm; And / or, the mechanical strength of the SEI film of the lithium metal battery is greater than or equal to 250 MPa.

[0012] The lithium metal battery as described in the first aspect, wherein the lithium replenishing agent comprises at least one of lithium dioxaborate, lithium formate, and lithium carbonate; And / or, the molar concentration of the lithium supplement in the electrolyte is 0.05 mol / L to 0.15 mol / L.

[0013] A second aspect of this application provides a method for preparing a lithium metal battery as described in the first aspect, comprising the following steps: S1. Immerse the carrier in an etching solution for etching treatment to obtain a carrier with a nanowire array on the surface; S2. A first deposition process and a second deposition process are sequentially performed on the surface of the carrier after etching in step S1 to obtain a negative electrode current collector; a modified coating is formed on the surface of the carrier. Wherein, the first coating slurry of the first deposition treatment includes a nucleation promoter and a reinforcing agent; the second coating slurry of the second deposition treatment includes an interface passivator and a structure stabilizer; S3. Inject electrolyte into the cell including the negative electrode current collector to obtain the lithium metal battery, wherein the electrolyte includes a lithium replenishing agent.

[0014] The method for preparing a lithium metal battery as described in the second aspect, wherein step S1 specifically includes: immersing a copper substrate in an etching solution containing alkaline salts for etching treatment. Wherein, the alkaline salt includes at least one of sodium hydroxide, potassium hydroxide and sodium carbonate; and / or, the molar concentration of the etching solution is 0.5 mol / L to 2 mol / L; And / or, the etching temperature of the etching process is 25℃~80℃, and the etching time is 30min~120min.

[0015] The method for preparing a lithium metal battery as described in the second aspect, wherein the solid content of the first coating slurry is 5% to 10%; and / or, the solid content of the second coating slurry is 8% to 15%; And / or, the deposition temperature of the first deposition treatment is 150℃~200℃, and the deposition period is 50s~100s; and / or, the deposition temperature of the second deposition treatment is 180℃~220℃, and the deposition period is 80s~150s.

[0016] The technical solution provided in this application may include the following beneficial effects: This application improves the performance of lithium metal batteries through the synergistic effect of a carrier with a nanowire array structure, a double-layer modified coating, and a lithium replenishing agent in the electrolyte. The synergistic mechanism is as follows: Firstly, the nanowire array structure increases the specific surface area of ​​the negative electrode current collector, providing an ideal three-dimensional substrate for the modified coating. This allows the bottom and top layers to uniformly and completely cover the surface and gaps of each nanowire, avoiding pinholes or uneven thickness issues that easily occur on planar substrates. This ensures the integrity of the SEI film formed on the negative electrode surface, thereby reducing battery side reactions and improving battery cycle performance. Secondly, the increased specific surface area of ​​the nanowire array structure for the negative electrode current collector provides sufficient nucleation sites for lithium ions, effectively reducing local current density and inhibiting lithium dendrite formation at the source. Simultaneously, its integrated three-dimensional structure avoids interface bonding risks, reduces contact resistance, and during lithium deposition, the nucleation promoter and reinforcing agent in the bottom layer work synergistically to reduce lithium nucleation overpotential and guide lithium to preferentially and uniformly deposit on the nanowire surface. The interface passivator and structural stabilizer in the top layer work synergistically, making the top layer a physical barrier to block abnormal lithium dendrite growth. The combination of these two factors makes lithium deposition more closely conform to the three-dimensional structure of the nanowires, preventing dendrites from randomly penetrating through the gaps between the nanowires. Firstly, the modified coating ensures the electrochemical stability of the battery. Secondly, it reduces direct contact between the electrolyte and lithium metal, inhibiting electrolyte decomposition and minimizing side reactions, thus improving cycle performance. Thirdly, during battery cycling, the three-dimensional porous structure of the nanowire array provides a buffer for volume changes during lithium deposition / stripping. Furthermore, the modified coating possesses high mechanical strength, capable of withstanding the stress caused by volume changes during lithium metal deposition / stripping, preventing SEI film rupture on the negative electrode surface. Simultaneously, the modified coating exhibits high ionic conductivity, ensuring uniform lithium ion transport during expansion / contraction, thereby guaranteeing electrode structural stability and long cycle life. Fourthly, the lithium replenishing agent in the electrolyte preferentially decomposes during the first cycle, effectively compensating for irreversible lithium loss caused by SEI film formation and irreversible lithium dendrite growth. Its decomposition products synergistically enhance the mechanical strength and ionic conductivity of the SEI film, achieving a dual effect of "dynamic lithium replenishment" and "interface stabilization," thereby improving the battery's initial coulombic efficiency and cycle performance.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Detailed Implementation

[0018] To facilitate understanding of this application, it will be described in detail below. However, before describing this application in detail, it should be understood that this application is not limited to the specific embodiments described. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be restrictive.

[0019] Where a numerical range is provided, it should be understood that every intermediate value between the upper and lower limits of the range and any other specified or intermediate value within the specified range is covered within this application. The upper and lower limits of these smaller ranges may be independently included in the smaller range and are also covered within this application, subject to any explicitly excluded limits within the specified range. Where the specified range includes one or two limits, the range excluding any or both of those included limits is also included within this application.

[0020] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While the methods and materials described herein, or any equivalent methods and materials, may also be used in the implementation or testing of this application, preferred methods and materials are now described.

[0021] In lithium metal batteries without negative electrode active materials (hereinafter referred to as negative electrode-free lithium metal batteries), the elimination of traditional negative electrode active materials in the negative electrode sheet gives them significant advantages in terms of improved energy density and reduced manufacturing costs, making them one of the core development directions for next-generation lithium-ion batteries. However, negative electrode-free lithium metal batteries in related technologies still face two major bottlenecks: First, uneven lithium deposition on the surface of the negative electrode current collector (such as copper foil) can easily lead to lithium dendrite growth, which can puncture the separator and cause a short circuit in the battery. At the same time, it increases the probability of electrolyte side reactions, resulting in the generation of "dead lithium" and a decrease in battery cycle life. Second, during the first charge, lithium ions extracted from the positive electrode need to complete nucleation and deposition on the surface of the negative electrode current collector. During this process, electrolyte decomposition and irreversible formation of the SEI film can lead to lithium ion loss, causing the battery's initial coulombic efficiency to be generally below 70%, which seriously restricts the actual energy output and application value of the battery.

[0022] To address the aforementioned issues, existing technologies have proposed various improvement schemes: for example, electroplating or sputtering modification of the current collector surface to enhance lithiophilicity, but these processes are complex and costly; optimizing the SEI film composition by adding additives such as fluoroethylene carbonate (FEC) to the electrolyte, but this only slightly improves lithium deposition uniformity and cannot fundamentally suppress lithium dendrites; using lithium metal powder as a lithium replenishing agent can improve initial efficiency, but lithium powder is prone to reacting with air, posing safety hazards during storage and assembly. Furthermore, existing artificial SEI films are mostly single-component structures, making it difficult to simultaneously meet the comprehensive requirements of interface stability, mechanical strength, and ion conductivity. Meanwhile, the nanostructural preparation of current collectors often relies on hydrothermal or template methods, which suffer from long reaction cycles and poor product consistency, hindering large-scale production.

[0023] To address the aforementioned problems, this application provides a lithium metal battery, comprising a positive electrode, a separator, a negative electrode current collector, and an electrolyte. The negative electrode current collector of this application includes a carrier and a modified coating disposed on at least one surface of the carrier. The surface of the carrier has a nanowire array; the modified coating includes a bottom layer and a top layer stacked together, the bottom layer including a nucleation promoter and a reinforcing agent, and the top layer including an interface passivator and a structural stabilizer; the electrolyte includes a lithium replenishing agent.

[0024] This application does not limit the choice of carrier, as long as the carrier surface has a nanowire array structure. A nanowire array refers to a highly ordered arrangement of nanoscale nanowires. This nanowire array can be obtained by any existing or improved preparation process such as chemical deposition, template synthesis, or vapor phase growth. Its material, diameter, length, spacing and other parameters can be flexibly adjusted according to the actual application requirements.

[0025] The negative electrode current collector of this application includes a modified coating, which is divided into a base layer and a surface layer. The base layer is disposed on the surface of the carrier, and the surface layer is disposed on the side of the base layer away from the current collector.

[0026] The underlying components of this application include nucleation promoters and reinforcing agents. The nucleation promoters in this application refer to compounds with high lithium-ion conductivity. This application does not limit the specific selection of nucleation promoters; they can be selected according to actual needs. For example, nucleation promoters can be lithium fluoride, lithium nitride, lithium oxide, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, etc. The reinforcing agents in this application refer to compounds with high mechanical properties. This application does not limit the specific selection of reinforcing agents; they can be selected according to actual needs. For example, reinforcing agents can be alumina, magnesium oxide, zirconium oxide, silicon dioxide, carbon nanotubes, etc.

[0027] The surface layer of this application comprises an interface passivator and a structural stabilizer. The interface passivator in this application refers to a compound with good compatibility with the electrolyte. This application does not limit the specific selection of the interface passivator; it can be selected according to actual needs. For example, the interface passivator can be lithium carbonate, lithium metaphosphate, lithium sulfate, lithium iron phosphate, etc. The structural stabilizer in this application refers to a compound with high thermal stability and high chemical stability. This application does not limit the specific selection of the structural stabilizer; it can be selected according to actual needs. For example, the structural stabilizer can be titanium oxide, cerium oxide, aluminum oxide, zirconium oxide, silicon dioxide, etc.

[0028] The lithium metal battery of this application also includes an electrolyte, which includes a lithium replenishing agent. This application does not limit the specific selection of the lithium replenishing agent; it can be selected according to actual needs.

[0029] According to the above-mentioned solution provided in this application, the growth of lithium dendrites in the battery can be suppressed, resulting in excellent initial coulombic efficiency and cycle performance. The applicant has analyzed the principle behind this and believes that the reason lies in the synergistic effect of the carrier with a nanowire array structure, the double-layer modified coating, and the lithium replenishing agent in the electrolyte, which jointly improve the performance of the lithium metal battery. The synergistic mechanism is as follows: Firstly, the nanowire array structure increases the specific surface area of ​​the negative electrode current collector, providing an ideal three-dimensional substrate for the modified coating. This allows the bottom and top layers to uniformly and completely cover the surface and gaps of each nanowire, avoiding pinholes or uneven thickness issues that easily occur on planar substrates. This ensures the integrity of the SEI film formed on the negative electrode surface, thereby reducing battery side reactions and improving battery cycle performance. Secondly, the increased specific surface area of ​​the nanowire array structure for the negative electrode current collector provides sufficient nucleation sites for lithium ions, effectively reducing local current density and inhibiting lithium dendrite formation at the source. Simultaneously, its integrated three-dimensional structure avoids interface bonding risks, reduces contact resistance, and during lithium deposition, the nucleation promoter and reinforcing agent in the bottom layer work synergistically to reduce lithium nucleation overpotential and guide lithium to preferentially and uniformly deposit on the nanowire surface. The interface passivator and structural stabilizer in the top layer work synergistically, making the top layer a physical barrier to block abnormal lithium dendrite growth. The combination of these two factors makes lithium deposition more closely conform to the three-dimensional structure of the nanowires, preventing dendrites from randomly penetrating through the gaps between the nanowires. Firstly, the modified coating ensures the electrochemical stability of the battery. Secondly, it reduces direct contact between the electrolyte and lithium metal, inhibiting electrolyte decomposition and minimizing side reactions, thus improving cycle performance. Thirdly, during battery cycling, the three-dimensional porous structure of the nanowire array provides a buffer for volume changes during lithium deposition / stripping. Furthermore, the modified coating possesses high mechanical strength, capable of withstanding the stress caused by volume changes during lithium metal deposition / stripping, preventing SEI film rupture on the negative electrode surface. Simultaneously, the modified coating exhibits high ionic conductivity, ensuring uniform lithium ion transport during expansion / contraction, thereby guaranteeing electrode structural stability and long cycle life. Fourthly, the lithium replenishing agent in the electrolyte preferentially decomposes during the first cycle, effectively compensating for irreversible lithium loss caused by SEI film formation and irreversible lithium dendrite growth. Its decomposition products synergistically enhance the mechanical strength and ionic conductivity of the SEI film, achieving a dual effect of "dynamic lithium replenishment" and "interface stabilization," thereby improving the battery's initial coulombic efficiency and cycle performance.

[0030] In one specific embodiment, the diameter of the nanowires in the nanowire array is 50nm~200nm, and the length is 1μm~5μm. For example, the diameter of the nanowires can be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, or 200nm, etc., and the length of the nanowires can be 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, or 5μm, etc. When the size of the nanowires in the nanowire array is within the above range, the specific surface area of ​​the negative electrode current collector can be significantly increased, providing sufficient nucleation sites for lithium ions, suppressing lithium dendrite growth to a greater extent, and providing a three-dimensional adhesion substrate for the modified coating, ensuring the uniformity and integrity of the load on the bottom and surface layers. At the same time, it can better provide buffer space for volume changes during lithium deposition / stripping, ensuring the integrity of the SEI film to a greater extent, thereby reducing the side reactions of the battery to a greater extent and improving the cycle performance of the battery.

[0031] In one specific embodiment, the nucleation promoter includes at least one of lithium fluoride, lithium nitride, and lithium oxide. When the above-mentioned compounds are selected as the nucleation promoter, the nucleation promoter can form stable chemical bonds or stable interfaces with lithium metal, or it itself has excellent lithium-ion conductivity, which can effectively reduce the nucleation overpotential. This is beneficial for guiding the uniform deposition of lithium metal on the nanowire surface, thereby reducing the abnormal growth of lithium dendrites, while ensuring efficient lithium-ion transport, and thus improving the cycle performance of the battery.

[0032] In one specific embodiment, the reinforcing agent includes at least one of aluminum oxide, magnesium oxide, and zirconium oxide. When the above-mentioned compounds are selected as the reinforcing agent, the reinforcing agents all have high mechanical strength and good chemical inertness, which can physically prevent lithium dendrite penetration and ensure the stability of the battery; secondly, these compounds have good lithium-ion conductivity, which can promote the rapid transport of lithium ions at the interface, thereby improving the cycle performance of the battery; and these reinforcing agents have good compatibility with the manufacturing process of lithium metal batteries, which helps to simplify the production process and reduce manufacturing costs.

[0033] In one specific embodiment, the interface passivating agent includes at least one of lithium carbonate, lithium metaphosphate, and lithium sulfate. When the above-mentioned compounds are selected as the interface passivating agent, the passivating agent exhibits excellent chemical stability and can form a synergistic effect with fluorine-containing compounds in the electrolyte, further reducing the direct contact between the electrolyte and lithium metal, thereby suppressing electrolyte decomposition to a greater extent and ultimately enabling the battery to exhibit better cycle performance.

[0034] In one specific embodiment, the structural stabilizer includes at least one of titanium dioxide (TiO2), cerium oxide (CeO2), and aluminum oxide (Al2O3). When the structural stabilizer is selected from the above compounds, it exhibits excellent thermal and chemical stability, maintains the structural integrity of the SEI film, and improves the ion conduction uniformity of the SEI film, thereby reducing battery side reactions, increasing the lithium-ion transport rate, further reducing the formation of lithium dendrites, and enabling the battery to exhibit better cycle performance.

[0035] In one specific embodiment, the mass ratio of nucleation promoter to reinforcing agent is (3~5):1, for example, the mass ratio of nucleation promoter to reinforcing agent can be 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, etc. Within this range, the nucleation promoter and reinforcing agent can better synergize. On the one hand, it can reduce the lithium nucleation overpotential to a greater extent, guide lithium to preferentially and uniformly deposit on the nanowire surface, and reduce the growth of lithium dendrites. On the other hand, it can make the modified coating exhibit better mechanical strength, physically prevent lithium dendrites from piercing, avoid the SEI film on the negative electrode surface from cracking, and at the same time improve the lithium ion transport rate, thereby improving the cycle performance of the battery.

[0036] In one specific embodiment, the mass ratio of the interface passivator to the structural stabilizer is (2~4):1, for example, the mass ratio of the interface passivator to the structural stabilizer can be 2:1, 2.5:1, 3:1, 3.5:1, or 4:1, etc. Within this range, the interface passivator and the structural stabilizer can achieve better synergistic effects, which can reduce the direct contact between the electrolyte and lithium metal to a greater extent, reduce battery side reactions, and at the same time, can better block the abnormal growth of lithium dendrites, ultimately achieving high cycle performance of the battery.

[0037] In one specific embodiment, the thickness of the modified coating is 13nm to 22nm, for example, the thickness of the modified coating can be 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm, 21nm, or 22nm. When the thickness of the modified coating is within the above range, this thickness is sufficient to form a continuous, dense, and defect-free interface protective layer, effectively blocking direct contact between the electrolyte and metallic lithium, suppressing side reactions. At the same time, the high mechanical strength of the modified coating can effectively prevent abnormal growth of lithium dendrites and resist volume change stress during lithium deposition / stripping, avoiding SEI film rupture. Furthermore, this nanoscale thickness can minimize the transport impedance of lithium ions in the interface layer, ensuring the efficiency and uniformity of ion migration dynamics, ultimately synergistically improving the battery's initial coulombic efficiency, cycle stability, and lifespan. In addition, the thickness of the modified coating is perfectly adapted to the three-dimensional structure of the nanowire array, jointly constructing a stable interface that can both guide lithium ion flow and withstand mechanical stress, thereby ensuring a long cycle life of the battery.

[0038] In one specific embodiment, the thickness of the bottom layer is 5nm to 10nm, for example, the thickness of the bottom layer can be 5nm, 6nm, 7nm, 8nm, 9nm, or 10nm. At this thickness, the bottom layer can significantly reduce the lithium nucleation overpotential, precisely guide the deposition behavior of lithium metal, avoid abnormal growth of lithium dendrites, and better exert a physical "barrier" effect to prevent lithium dendrites from piercing, ensuring the high stability of the battery. Moreover, it can minimize ion transport impedance and improve the cycle performance of the battery.

[0039] In one specific embodiment, the thickness of the surface layer is 8nm to 12nm, for example, the thickness of the surface layer can be 8nm, 9nm, 10nm, 11nm, or 12nm. This surface layer thickness, together with the thickness of the underlying layer, forms a synergistic composite structure. At this thickness, the surface layer can fully utilize the established uniform deposition base of the underlying layer, providing the main mechanical barriers and chemical passivation functions, better reducing direct contact between the electrolyte and lithium metal and preventing abnormal growth of lithium dendrites, thereby ensuring high cycle performance of the battery.

[0040] In one specific embodiment, the ionic conductivity of the SEI film in the lithium metal battery is greater than or equal to 5 × 10⁻⁶. -6 For example, the ionic conductivity of the SEI film in a lithium metal battery can be 5 × 10⁻⁶ S / cm. -6 S / cm, 6×10 -6 S / cm, 7×10 -6 S / cm, 8×10 -6 S / cm, 9×10 -6 S / cm or 10×10 -6S / cm, etc. When the ionic conductivity of the SEI film of a lithium metal battery is within the above range, a sufficiently high ionic conductivity ensures that lithium ions can quickly pass through the three-dimensional interface constructed by the nanowire array and the double coating, thereby better reducing the nucleation overpotential, facilitating the uniform deposition of lithium metal on the nanowire surface, avoiding abnormal growth of lithium dendrites, and increasing the lithium ion transport rate, ultimately improving the cycle performance of the battery.

[0041] Specifically, the ionic conductivity of the SEI film in lithium metal batteries can be achieved through "symmetric cell electrochemical impedance spectroscopy (EIS) testing." Using copper foil coated with a double layer of SEI as electrodes, Li|Cu symmetric cells were assembled, and the conductivity was measured in the range of 0.1-10. 6 Impedance spectrum was measured in the Hz frequency range, and the interface resistance (RI) of the SEI film was obtained by equivalent circuit fitting. sei ), and combined with the thickness of the SEI film (13-22nm), the formula σ=L / (R) is used. sei The result is calculated as (σ = L × S) (where σ is the ionic conductivity, L is the film thickness, and S is the electrode area).

[0042] In one specific embodiment, the mechanical strength of the SEI film in the lithium metal battery is greater than or equal to 250 MPa. For example, the mechanical strength of the SEI film in the lithium metal battery can be 250 MPa, 260 MPa, 270 MPa, 280 MPa, 290 MPa, or 300 MPa. When the mechanical strength of the SEI film is within this range, sufficient mechanical strength can effectively prevent lithium dendrites from piercing the film, while also enabling the SEI film to withstand the volumetric stress generated during lithium deposition / stripping, avoiding SEI film rupture, reducing battery side reactions, and thus ensuring the structural stability and long cycle life of the electrode.

[0043] Specifically, the mechanical strength of the SEI film in lithium metal batteries can be verified through "nanoindentation testing" or "atomic force microscopy (AFM) mechanical mode testing". In nanoindentation testing, a diamond indenter is used to apply a small pressure (usually on the order of μN) to the surface of the SEI film, and the relationship between the indentation depth and the load is recorded. The hardness (H) and elastic modulus (E) of the film layer are calculated using the Oliver-Pharr model, and then the mechanical strength is calculated. AFM mechanical mode, on the other hand, maps the local modulus distribution of the film layer through the interaction force between the probe and the film surface, and verifies the uniformity of the overall mechanical strength.

[0044] In one specific embodiment, the lithium replenishing agent includes at least one of lithium dioxaborate, lithium formate, and lithium carbonate. The decomposition potentials of lithium dioxaborate, lithium formate, and lithium carbonate match the initial delithiation potential of the positive electrode, allowing lithium replenishment to be completed before lithium-ion deposition. This avoids the safety hazards of reactions between traditional lithium replenishing agents (such as lithium metal powder and Li3N) and the electrolyte. At the same time, the decomposition products can optimize the SEI film composition, achieving the dual benefits of "lithium replenishment and interface stabilization".

[0045] In one specific embodiment, the molar concentration of the lithium replenishing agent in the electrolyte is 0.05 mol / L to 0.15 mol / L. For example, the molar concentration of the lithium replenishing agent can be 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, 0.1 mol / L, 0.11 mol / L, 0.12 mol / L, 0.13 mol / L, 0.14 mol / L, or 0.15 mol / L. Within this range, the lithium replenishing agent can significantly compensate for the irreversible lithium loss of the battery, and its decomposition products can have a better synergistic effect with the modified coating, resulting in higher mechanical strength and ionic conductivity of the SEI film, ultimately balancing the battery's initial coulombic efficiency and cycle performance. If the molar concentration of the lithium replenisher is below 0.05 mol / L, the lithium replenishment effect is poor, making it difficult to effectively compensate for irreversible lithium loss caused by SEI formation during the first cycle, thus degrading the battery's first coulombic efficiency. If the molar concentration of the lithium replenisher is above 0.15 mol / L, it may lead to problems such as excessive electrolyte viscosity and aggravated side reactions in the battery, which is detrimental to the long-term cycle stability of the battery.

[0046] In one specific embodiment, the electrolyte further includes a lithium salt, which includes at least one selected from lithium hexafluorophosphate, lithium difluorooxalate borate, lithium bis(oxalate borate), lithium difluorodioxalate phosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium difluorophosphate, and lithium cyano(trifluoromethanesulfonyl)imide. The molar concentration of the lithium salt in the electrolyte is 1.0 mol / L to 1.2 mol / L, for example, 1 mol / L, 1.05 mol / L, 1.1 mol / L, 1.15 mol / L, or 1.2 mol / L. When the selection of the lithium salt and the molar concentration are within the above range, the conductivity and stability of the electrolyte can be further improved, thereby further improving the cycle performance of the battery.

[0047] In one specific embodiment, the electrolyte includes an organic solvent, which may include ethylene carbonate, dimethyl carbonate, diethyl carbonate, propylene carbonate, methyl ethyl carbonate, ethyl propionate, propyl propionate, ethyl fluorocarbonate, methyl ethyl fluorocarbonate, dimethyl fluorocarbonate, propylene fluorocarbonate, γ-ray dimethyl carbonate, methyl fluorocarbonate, ethyl fluorocarbonate, γ-ray dimethyl carbonate, methyl fluorocarbonate, γ-ray dimethyl carbonate, methyl fluorocarbonate, ethyl ... The electrolyte contains at least one of the following: butyrolactone, sulfolane, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, methyl propionate, methyl butyrate, n-ethyl butyrate, methyl acrylate, and ethyl acrylate. When the organic solvent of the electrolyte is selected from the above-mentioned organic solvents, the lithium supplement in the electrolyte exhibits higher dispersibility, lower viscosity, and higher ionic conductivity, which is beneficial for improving the migration rate of lithium ions. Furthermore, the above-mentioned organic solvents can improve the stability of the electrolyte, preventing decomposition reactions and thus further improving the cycle performance of the battery.

[0048] In one specific embodiment, the lithium metal battery further includes a positive electrode sheet, which comprises a positive current collector and a positive electrode coating coated on the current collector. The positive electrode coating comprises a positive electrode active material, which includes NCM811 ternary material and / or lithium iron phosphate. When the above-mentioned compounds are selected as the positive electrode active material, the positive electrode active material can fully exert its performance and improve the electrochemical performance of the battery. The thickness of the positive electrode sheet in this application is 80 μm to 100 μm.

[0049] In this application embodiment, there is no particular limitation on the type of positive electrode current collector; it can be any known material suitable for use as a positive electrode current collector. In one embodiment, the positive electrode current collector includes metallic materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, as well as carbon materials such as carbon cloth and carbon paper. Preferably, the positive electrode current collector is a metallic material.

[0050] In one specific embodiment, the positive electrode coating further includes a conductive agent and a binder. The conductive agent includes at least one of carbon materials such as natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, graphene, and vapor-grown carbon fiber (VGCF). The binder includes at least one of polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose, polyvinylidene fluoride, and polytetrafluoroethylene.

[0051] In one specific embodiment, the lithium metal battery further includes a separator. This application does not impose particular limitations on the material and shape of the separator, as long as it does not significantly impair the effectiveness of this application. The separator may include porous sheet-like or non-woven materials with excellent liquid retention properties. The materials for resin or glass fiber separators include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylene, and polyethersulfone, etc., and can be specifically configured as needed. The thickness of the separator in this application is 12μm~16μm.

[0052] In one embodiment, the battery may include an outer packaging that can be used to encapsulate the electrode assembly and electrolyte.

[0053] In one specific embodiment, the outer packaging of the battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch-type soft pack. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0054] This application does not impose any particular restrictions on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape.

[0055] This application does not impose any particular restrictions on the application fields of lithium metal batteries, and they can be used in fields such as consumer batteries, power batteries for new energy vehicles, and energy storage batteries.

[0056] A second aspect of this application provides a method for preparing a lithium metal battery, comprising the following steps: S1. Immerse the carrier in an etching solution for etching treatment to obtain a carrier with a nanowire array on the surface; S2. The surface of the carrier after etching in step S1 is subjected to a first deposition treatment and a second deposition treatment in sequence to obtain a negative electrode current collector; a modified coating is formed on the surface of the carrier. The first coating slurry for the first deposition treatment includes a nucleation promoter and a reinforcing agent; the second coating slurry for the second deposition treatment includes an interface passivator and a structure stabilizer. S3. Electrolyte is injected into a cell including a negative electrode current collector to obtain a lithium metal battery. The electrolyte includes a lithium replenishing agent.

[0057] Specifically, in step S1, an etching solution is prepared, and then the carrier is immersed in the etching solution for etching treatment to obtain a carrier with a nanowire array structure on its surface.

[0058] The carrier of this application can be pretreated copper foil or foamed copper. For example, commercial copper foil (thickness 8μm~12μm) or foamed copper (porosity 80%~90%) can be used. The copper foil is ultrasonically cleaned with deionized water and anhydrous ethanol in sequence, with each cleaning time being 10min~15min, and repeated 3 times to remove surface oil, oxide layer and impurities. Then, it is dried in a vacuum oven at 60℃~80℃ for 2h~4h to obtain the pretreated copper foil or foamed copper.

[0059] After etching, the substrate is cleaned. For example, the etched copper substrate is rinsed with deionized water until the pH is neutral, then dehydrated with anhydrous ethanol, and finally dried in a vacuum oven at 70°C for 3 hours to obtain a substrate with a nanowire array structure.

[0060] In step S2, the nucleation promoter and reinforcing agent are dispersed in a solvent at a specific mass ratio to obtain a first coating slurry; the interface passivator and structural stabilizer are dispersed in a solvent at a specific mass ratio to obtain a second coating slurry; then, the first coating slurry is loaded onto the surface of a carrier with a nanowire array through a first deposition process to form a bottom layer, and then the second coating slurry is loaded onto the surface of the bottom layer through a second deposition process to form a top layer, thereby obtaining a negative electrode current collector including a modified coating.

[0061] This application does not limit the specific choice of solvent, which can be selected according to actual needs, such as N-methylpyrrolidone (NMP).

[0062] The first and second deposition processes of this application can be performed using pulsed laser deposition (PLD) technology.

[0063] In step S3, the negative electrode current collector, separator, and positive electrode are wound to form a battery cell. Then, an electrolyte including a lithium replenishing agent is prepared, and the electrolyte is injected into the battery cell. The cell is then packaged and formed to obtain a lithium metal battery.

[0064] The lithium metal battery preparation method provided in this application is based on a three-step process to construct a negative electrode current collector and combine it with an electrolyte containing a lithium replenishing agent: First, a carrier is treated with chemical etching to form a carrier with a nanowire array; then, a first deposition treatment is performed on the surface of the carrier to construct a uniform and dense bottom layer composed of a nucleation promoter and a reinforcing agent; then, a second deposition treatment is performed on the surface of the bottom layer to form a surface layer composed of an interface passivator and a structural stabilizer; finally, an electrolyte containing a lithium replenishing agent is injected into the cell to obtain a lithium metal battery.

[0065] The negative electrode current collector exhibits a layered structure of "carrier-bottom layer-top layer". The layers in this negative electrode current collector are tightly connected through physical interlocking and work synergistically with the lithium replenishing agent in the electrolyte to achieve multiple performance optimizations: the nanowire array structure helps reduce local current density and inhibits the formation of lithium dendrites; the bottom layer and the top layer work together to reduce the lithium nucleation overpotential, guide lithium to preferentially and uniformly deposit on the nanowire surface, and effectively block the abnormal growth of lithium dendrites. At the same time, it can provide a buffer space for volume changes during lithium deposition / stripping, ensuring the integrity of the SEI film, and also improving lithium-ion transport efficiency to ensure the cycle performance of the battery; the lithium replenishing agent in the electrolyte can further work synergistically with the bottom layer and the top layer to enhance the mechanical strength and ionic conductivity of the SEI film, and improve the battery's initial coulombic efficiency and cycle performance.

[0066] Furthermore, the chemical etching method for preparing the carrier can shorten the process cycle, and the etching process does not require a high-pressure reactor, reducing equipment requirements and costs. At the same time, it can precisely control the nanowire size and produce excellent product consistency. The modified coating is prepared by pulsed laser deposition (PLD) technology through a first deposition process and a second deposition process. This technology is simple and has high deposition efficiency. Finally, a simple electrolyte encapsulation is performed. The entire preparation process is simple and has low dependence on equipment, which is conducive to the industrial application of this preparation method.

[0067] In one specific embodiment, step S1 specifically includes: immersing the copper substrate in an etching solution containing an alkaline salt for etching. The alkaline salt in this application refers to a salt compound whose solution has a pH greater than 7 after dissolving in water. This application does not limit the specific selection of the alkaline salt, as long as it can form an alkaline etching solution. By etching the copper substrate, this application can obtain a carrier with a specific nanowire array structure. This etching process is highly efficient, simple to operate, and has low equipment and cost requirements.

[0068] In one specific embodiment, the alkaline salt includes at least one selected from sodium hydroxide, potassium hydroxide, and sodium carbonate. The etching solution prepared from the above-mentioned alkaline salt can effectively etch a copper substrate, forming a carrier with a nanowire array structure, and the etching rate is stable, avoiding problems such as excessive corrosion of the copper substrate or uneven nanowire growth caused by excessively rapid local etching rates. Furthermore, the above-mentioned alkaline salts can be used in combination to synergistically regulate the OH content in the etching solution. - The concentration and etching rate of the alkali salt can ensure etching efficiency, shorten process time, and maintain the stability of the etching process, avoiding damage to the copper substrate. Preferably, the alkali salt includes sodium hydroxide.

[0069] In one specific embodiment, the molar concentration of the etching solution is 0.5 mol / L to 2 mol / L. For example, the molar concentration of the etching solution can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, or 2 mol / L, etc. Using the etching solution of the above specific concentration can rapidly etch the copper substrate to form a nanowire array structure while effectively avoiding problems such as poor mechanical properties caused by excessive corrosion of the copper substrate, thus laying a good foundation for the preparation of the negative electrode current collector.

[0070] In one specific embodiment, the etching temperature is 25℃~80℃, and the etching time is 30min~120min. For example, the etching temperature can be 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, or 80℃, and the etching time can be 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, or 120min, etc. This application adjusts the size of the nanowires by controlling the etching temperature and etching time: for every 10℃ increase in temperature, the etching rate increases by 15%~20%; for every 30min extension of the time, the length of the nanowires increases by 1μm~1.5μm. When the etching parameters are within the above range, it is beneficial to control the diameter and length of the nanowires in the carrier to be within the range of 50nm~200nm and 1μm~5μm, respectively, thereby preparing a carrier with nanowire arrays of specific parameters. If the etching temperature exceeds 80℃ or the etching time exceeds 120min, the copper substrate will be over-etched, resulting in excessively large diameters and lengths of the nanowires. This will significantly reduce the mechanical properties of the copper substrate, decrease the stability of the negative electrode current collector, and ultimately degrade the cycle stability of the battery. If the etching temperature is below 25℃ or the etching time is less than 30min, the etching rate will be too slow or the etching effect will be insufficient, making it difficult to form a nanowire array. This will make it difficult for the carrier to achieve its expected goals, thus making it difficult to control the growth of lithium dendrites and degrade the cycle performance of the battery.

[0071] In one specific embodiment, the solid content of the first coating slurry is 5% to 10%, for example, the solid content of the first coating slurry can be 5%, 6%, 7%, 8%, 9%, or 10%, etc. The first coating slurry of this application includes a nucleation promoter, a reinforcing agent, and a solvent. The solid content of the first coating slurry is the ratio of the total mass of the nucleation promoter and reinforcing agent to the total mass of the nucleation promoter, reinforcing agent, and solvent. When the solid content of the first coating slurry is within the above range, the first coating slurry can be uniformly deposited on the surface and gaps of the nanowire array through the first deposition process, forming a uniform and dense bottom layer, avoiding problems such as pinholes and localized excessive thickness, and ensuring the successful preparation of the negative electrode current collector.

[0072] In one specific embodiment, the solid content of the second coating slurry is 8% to 15%, for example, the solid content of the second coating slurry can be 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%, etc. The second coating slurry of this application includes an interface passivator, a structural stabilizer, and a solvent. The solid content of the first coating slurry is the ratio of the total mass of the interface passivator and structural stabilizer to the total mass of the interface passivator, structural stabilizer, and solvent. When the solid content of the second coating slurry is within the above range, it helps the second coating slurry to deposit on the surface of the underlying layer to form a uniform and dense surface layer, achieving a tight bond between the underlying layer and the surface layer, resulting in a high-performance negative electrode current collector.

[0073] In one specific embodiment, the deposition temperature of the first deposition treatment is 150℃~200℃, and the deposition period is 50s~100s. For example, the deposition temperature of the first deposition treatment can be 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃, and the deposition period can be 50s, 60s, 70s, 80s, 90s, or 100s. When the parameters of the first deposition treatment are within the above range, the first coating slurry can fully cover the surface and gaps of the nanowire array, forming a bottom layer with a specific thickness, avoiding the degradation of the negative electrode current collector performance caused by an excessively thick or thin bottom layer.

[0074] In one specific embodiment, the deposition temperature of the second deposition treatment is 180℃~220℃, and the deposition period is 80s~150s. For example, the deposition temperature of the second deposition treatment can be 180℃, 190℃, 200℃, 210℃, or 220℃, and the deposition period can be 80s, 90s, 100s, 110s, 120s, 130s, 140s, or 150s, etc. When the deposition temperature of the second deposition treatment is within the above range, the second coating slurry can be uniformly deposited on the surface of the substrate to form a uniform and dense surface layer, thus obtaining a negative electrode current collector with a three-layer structure of "carrier-substrate-surface layer".

[0075] In one specific embodiment, after the second deposition treatment, the negative electrode current collector can be annealed at a temperature of 80°C to 120°C for 1 to 3 hours. Annealing the negative electrode current collector enables a tighter bond between the carrier, the bottom layer, and the top layer, enhancing the bonding force and improving the chemical and mechanical stability of the negative electrode current collector. This, in turn, can suppress the growth of lithium dendrites in the battery and extend the battery's cycle life.

[0076] It should be noted that this application does not impose any particular limitation on the preparation method of the electrolyte. Those skilled in the art can prepare the electrolyte using conventional technical means, such as mixing the raw materials evenly according to the specified ratio.

[0077] A third aspect of this application provides an electronic device including the lithium metal battery described above.

[0078] For example, the aforementioned electronic devices may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.

[0079] The present application will be further described in detail below through specific embodiments.

[0080] Example 1 1. Preparation of negative electrode current collector Substrate pretreatment: Take commercial copper foil (10μm thick), and ultrasonically clean it sequentially with deionized water and anhydrous ethanol for 12 minutes each time, repeating 3 times to remove surface oil, oxide layer and impurities. Then dry it in a vacuum oven at 80℃ for 3 hours for later use.

[0081] Etching solution preparation: Add sodium hydroxide to deionized water and stir until completely dissolved to obtain an etching solution with a concentration of 2 mol / L.

[0082] Nanowire array formation: The copper foil was immersed in the etching solution and etched at 35°C for 60 min. After removal, it was rinsed with deionized water until pH=7, dehydrated with anhydrous ethanol, and vacuum dried at 70°C for 3 h to obtain a carrier with nanowire diameter of 100nm~150nm and length of 2μm~3μm.

[0083] Preparation of modified coatings: Bottom Layer: Lithium fluoride (LiF) powder (purity ≥99.9%), a nucleation promoter, and alumina (Al2O3) powder (particle size 5nm~10nm) were mixed at a mass ratio of 4:1 and added to N-methylpyrrolidone (NMP). The mixture was ultrasonically dispersed for 30 min to obtain a first coating slurry with a solid content of 8%. Pulsed laser deposition (PLD) technology was used to coat the nanowire array surface of the carrier with the first coating slurry. The deposition temperature was 180℃, the deposition period was 80 s, and the bottom layer thickness was controlled to be 8 nm.

[0084] Surface Layer: Lithium carbonate (Li₂CO₃) powder (purity ≥ 99.9%) and titanium oxide (TiO₂) powder (particle size 8 nm ~ 15 nm) were mixed at a mass ratio of 3:1, added to NMP, and ultrasonically dispersed for 40 min to obtain a second coating slurry with a solid content of 12%. The second coating slurry was then applied to the surface of the substrate with the already coated underlayer using PLD technology. The deposition temperature for the second deposition treatment was 200℃, the deposition cycle was 120 s, and the surface layer thickness was controlled to be 10 nm. After coating, the surface layer was annealed in a vacuum oven at 100℃ for 2 h to obtain the negative electrode current collector.

[0085] 2. Preparation of electrolyte In an environment with a water content of less than 10 ppm, ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) were mixed in a mass ratio of 2:1:1. Based on the total mass of the electrolyte, lithium hexafluorophosphate (LiPF6) was added to the solvent, dissolved, and mixed thoroughly. Then, lithium oxalate borate (LiBOB) was added to obtain the electrolyte. The molar concentration of LiPF6 in the electrolyte was 1.1 mol / L, and the molar concentration of LiBOB in the electrolyte was 0.1 mol / L.

[0086] 3. Preparation of positive electrode sheet The positive electrode active material NCM811, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) binder were mixed evenly at a mass ratio of 94:3:3. The mixture was then thoroughly stirred in N-methylpyrrolidone solvent to prepare a slurry with a solid content of 45%, which was then stirred evenly to obtain the positive electrode slurry. The positive electrode slurry was uniformly coated onto one surface of an aluminum foil, dried at 90°C, and cold-pressed to obtain a positive electrode sheet with a coating thickness of 90 μm. The above steps were then repeated on the other surface of the same positive electrode sheet to obtain a positive electrode sheet with a double-sided coating. The positive electrode sheet was then cut and had tabs welded on for later use.

[0087] 4. Manufacturing of lithium metal batteries The battery cell is assembled in the following order: negative electrode current collector, separator (PE / PP composite membrane, 14μm thick), and positive electrode. Then, a prepared electrolyte is injected at a rate of 6μL / cm³. 2 The soft-pack batteries are assembled inside the glove box and allowed to stand for 24 hours to form (charged to 4.3V at 0.1C, left to stand for 1 hour, and discharged to 2.7V at 0.1C).

[0088] Example 2 1. Preparation of negative electrode current collector Substrate pretreatment: Take commercial foam copper (porosity 85%), and clean it with deionized water and anhydrous ethanol in sequence by ultrasonic cleaning for 15 minutes each time, repeating 3 times to remove surface oil, oxide layer and impurities. Then dry it in a vacuum oven at 70℃ for 4 hours for later use.

[0089] Etching solution preparation: Add potassium hydroxide to deionized water and stir until completely dissolved to obtain an etching solution with a concentration of 1.5 mol / L.

[0090] Nanowire array formation: copper foam was immersed in etching solution and etched at 40°C for 90 min. After removal, it was rinsed with deionized water until pH=7, dehydrated with anhydrous ethanol, and vacuum dried at 70°C for 3 h to obtain a carrier with nanowire diameter of 150 nm~200 nm and length of 3 μm~4 μm.

[0091] Preparation of modified coatings: Bottom Layer: Lithium fluoride (LiF) powder (purity ≥99.9%) and alumina (Al2O3) powder (particle size 5nm~10nm) were mixed at a mass ratio of 5:1, added to N-methylpyrrolidone (NMP), and ultrasonically dispersed for 30 min to obtain a first coating slurry with a solid content of 10%. Pulsed laser deposition (PLD) technology was used to coat the first coating slurry onto the surface of the nanowire array on the carrier. The temperature of the first deposition treatment was 200℃, the deposition cycle was 100s, and the bottom layer thickness was controlled to be 10nm.

[0092] Surface Layer: Lithium carbonate (Li₂CO₃) powder (purity ≥ 99.9%) and titanium oxide (TiO₂) powder (particle size 8 nm ~ 15 nm) were mixed at a mass ratio of 4:1, added to NMP, and ultrasonically dispersed for 40 min to obtain a second coating slurry with a solid content of 15%. The second coating slurry was then applied to the surface of the substrate with the already coated underlayer using PLD technology. The deposition temperature for the second deposition treatment was 220℃, the deposition cycle was 150 s, and the surface layer thickness was controlled to be 12 nm. After coating, the surface layer was annealed in a vacuum oven at 100℃ for 2 h to obtain the negative electrode current collector.

[0093] 2. Preparation of electrolyte In an environment with a water content of less than 10 ppm, ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) were mixed in a mass ratio of 2:1:1. Based on the total mass of the electrolyte, lithium hexafluorophosphate (LiPF6) was added to the solvent, dissolved, and mixed thoroughly. Then, lithium oxalate borate (LiBOB) was added to obtain the electrolyte. The molar concentration of LiPF6 in the electrolyte was 1.2 mol / L, and the molar concentration of LiBOB in the electrolyte was 0.15 mol / L.

[0094] 3. Preparation of positive electrode sheet Lithium iron phosphate (LiFePO4), conductive carbon black (SP), and polyvinylidene fluoride (PVDF) binder were mixed uniformly at a mass ratio of 93:4:3. The mixture was then thoroughly stirred in N-methylpyrrolidone solvent to prepare a slurry with a solid content of 48%. This slurry was then stirred until homogeneous, yielding the positive electrode slurry. The positive electrode slurry was uniformly coated onto one surface of an aluminum foil, dried at 90°C, and cold-pressed to obtain a positive electrode sheet with a coating thickness of 100 μm. The above steps were then repeated on the other surface of the same positive electrode sheet to obtain a positive electrode sheet with a double-sided coating. The positive electrode sheet was then cut and had tabs welded on for later use.

[0095] 4. Manufacturing of lithium metal batteries The battery cell is assembled in the following order: negative electrode current collector, separator (PE / PP composite membrane, 14μm thick), and positive electrode. Then, a prepared electrolyte is injected at a rate of 6μL / cm³. 2 The soft-pack batteries are assembled inside the glove box and allowed to stand for 24 hours to form (charged to 4.3V at 0.1C, left to stand for 1 hour, and discharged to 2.7V at 0.1C).

[0096] Comparative Example 1 The preparation method of the lithium metal battery in this comparative example is roughly the same as that in Example 1, except that commercial copper foil (without nanowire array and modified coating) is used as the negative electrode current collector, and lithium dioxaborate is not added to the electrolyte.

[0097] Comparative Example 2 The preparation method of the lithium metal battery in this comparative example is roughly the same as that in Example 1, except that the negative electrode current collector is a commercial copper foil with a nanowire array (without modified coating), and lithium dioxalate borate is not added to the electrolyte.

[0098] Comparative Example 3 The preparation method of the lithium metal battery in this comparative example is roughly the same as that in Example 1, except that lithium dioxaborate is not added to the electrolyte.

[0099] Comparative Example 4 The preparation method of the lithium metal battery in this comparative example is roughly the same as that in Example 1, except that the negative electrode current collector is a commercial copper foil with a nanowire array (without modified coating).

[0100] Comparative Example 5 The preparation method of the lithium metal battery in this comparative example is roughly the same as that in Example 1, except that the negative electrode current collector is a commercial copper foil with a modified coating (without nanowire array).

[0101] Comparative Example 6 The preparation method of the lithium metal battery in this comparative example is roughly the same as that in Example 1, except that the negative electrode current collector is a commercial copper foil with a modified coating (without nanowire array), and lithium dioxaborate is not added to the electrolyte.

[0102] Comparative Example 7 The preparation method of the lithium metal battery in this comparative example is roughly the same as that in Example 1, except that the negative electrode current collector is made of commercial copper foil (without nanowire array and modified coating).

[0103] The main difference between Examples 3-41 and Example 1 is the parameters of the negative electrode current collector and the electrolyte. Please refer to Tables 1, 2, 3 and 4.

[0104] Table 1

[0105] Table 2

[0106] Table 3

[0107] Table 4

[0108] Test case The following performance tests were performed on the batteries prepared in the examples and comparative examples: 1. Initial Coulomb efficiency In a constant temperature chamber at (25±2)℃, the lithium metal battery was charged to 4.2V at a constant current and constant voltage of 0.1C, cut off at 0.05C, and then discharged to 2.5V at 0.1C after standing for 5 minutes.

[0109] Initial coulombic efficiency (%) = (initial discharge capacity ÷ initial charge capacity) × 100%.

[0110] 2. Cyclic performance test In a constant temperature chamber at (25±2)℃, the lithium metal battery was charged to 4.2V at a constant current and constant voltage of 1.0C, then charged to 0.05C at a constant voltage. After resting for 5 minutes, it was discharged to 2.5V at 1.0C. The capacity obtained in this step was taken as the initial capacity. Cyclic tests were performed using 1.0C charge / 1.0C discharge, and the capacity retention rate of the battery after 500 cycles was calculated.

[0111] Cycle capacity retention (%) = Discharge capacity at 500th cycle (mAh) / Discharge capacity at first cycle (mAh) × 100%.

[0112] 3. Needle prick test (1) Fix the battery sample horizontally on the insulating clamp to ensure that the battery does not shift during the puncture process. Select the geometric center of the battery as the puncture point (avoid the tab area), as this is the area where stress concentration is most likely to cause thermal runaway. (2) Puncture execution: Start the needle puncture device and use a stainless steel needle (select a stainless steel needle with a diameter of 3mm and a tip angle of 30° (hardness ≥ HRC50) to ensure that the needle tip is sharp and burr-free) to puncture the center of the battery vertically at a set speed of 5±1mm / s. After the puncture is completed, keep the needle tip inside the battery for 30 minutes. During this period, do not touch the sample or equipment. (3) After the puncture, continue to observe the battery for 2 hours. If a fire occurs, immediately cover it with a fire blanket to extinguish the fire. If no safety risk occurs, after the battery temperature drops to the ambient temperature, transfer the sample into a special waste liquid recovery container.

[0113] Safety (%) = Number of batteries that did not catch fire / Total number of batteries tested × 100%.

[0114] 4. Low temperature test In a constant temperature chamber at (25±2)℃, the lithium metal battery was charged at a constant current and constant voltage of 1.0C to 4.2V, then charged at a constant voltage to 0.05C, and after resting for 5 minutes, discharged at 1.0C to 2.5V. The capacity obtained in this step is the initial capacity. In a constant temperature chamber at (-20±2)℃, the lithium metal battery was charged at a constant current and constant voltage of 1.0C to 4.2V, then charged at a constant voltage to 0.05C, and after resting for 5 minutes, discharged at 1.0C to 2.5V. The capacity obtained in this step is the -20℃ discharge capacity. Calculate the capacity retention rate during -20℃ low-temperature discharge.

[0115] -20℃ low temperature capacity retention rate (%) = -20℃ discharge capacity (mAh) / first cycle discharge capacity (mAh) × 100%.

[0116] Each group contains 10 batteries, and the average value is recorded in Tables 5 to 8.

[0117] Table 5

[0118] Table 6

[0119] Table 7

[0120] Table 8

[0121] Table 1 reveals the control over nanowire size by etching process parameters on the copper substrate, clearly demonstrating the strong correlation between "concentration-temperature-time" and nanowire diameter / length, as detailed below: Effect of etching solution concentration: Under the same temperature and conditions, the etching solution concentration is positively correlated with the nanowire size. As the concentration increases (e.g., 2.5 mol / L NaOH in Example 11 vs. 0.3 mol / L in Example 10), the OH concentration increases. - With increasing content, the oxidation and dissolution rate of the copper substrate accelerates, and the diameter of the nanowires increases from 40nm~80nm to 180nm~250nm, while the length increases from 0.8μm~1.2μm to 4.5μm~5.5μm; with decreasing concentration, the growth of nanowires is limited, and the size decreases significantly.

[0122] Effect of etching temperature: Under the same concentration and conditions, etching temperature is positively correlated with nanowire size. Increasing the temperature (e.g., 80℃ in Example 7 vs. 25℃ in Example 6) increases reactivity, with nanowire diameters increasing from 70nm~90nm to 170nm~190nm and lengths from 1.3μm~1.7μm to 4.5μm~5μm. Lower temperatures beyond the critical range (20℃ in Example 8) require extended time compensation rates, but still struggle to form long nanowires. Ultra-high temperatures (90℃ in Example 9) easily lead to excessive nanowire growth and increased size deviations.

[0123] Effect of etching time: Under the same concentration and temperature conditions, etching time is positively correlated with nanowire size. With longer etching times (e.g., 120 min in Example 6 vs. 30 min in Example 3), the copper substrate is etched more thoroughly, and the nanowire length decreases from 2.8 μm~3.2 μm to 1.3 μm~1.7 μm (Note: Example 6 had a lower temperature, and the extended time only partially offset the loss in etching rate at low temperatures; the length is still lower than the short-time group at room temperature). If the time is too short (Example 9, 20 min), even at high temperature and high concentration, the nanowire length is difficult to meet the standard; if the time is too long, the nanowires are prone to collapse.

[0124] Effect of Alkali Salt Type: Under the same concentration, temperature, and conditions, the etching rate is determined by the alkalinity of the alkali salt; the stronger the alkalinity, the larger the size. NaOH / KOH is more alkaline than Na2CO3. The nanowires in Examples 3 (NaOH) and 4 (KOH) have larger diameters (110nm~130nm, 100nm~120nm) and lengths (2.8μm~3.2μm, 2.6μm~3.0μm) than those in Example 5 (Na2CO3, 80nm~100nm, 2.0μm~2.4μm).

[0125] Table 2 focuses on the composition ratio and thickness design of the double-layer modified coating, embodying the principle of "component matching function and thickness matching process," as detailed below: The influence of the composition ratio of the bottom layer: The core function of the bottom layer is to optimize ion conduction. The proportion of LiF is positively correlated with ion conduction efficiency, while the proportion of Al2O3 is positively correlated with structural stability. Increasing the LiF-Al2O3 ratio (e.g., 5:1 in Example 17 vs. 3:1 in Example 16) enhances the density of the coating, and the thickness of the bottom layer can be reduced from 10nm to 5nm; decreasing the ratio requires increasing the thickness (10nm) to compensate for insufficient structural strength and avoid coating cracking.

[0126] The influence of surface layer composition ratio: The core function of the surface layer is to enhance mechanical support. The TiO2 / CeO2 ratio is positively correlated with mechanical strength, while the Li2CO3 ratio is positively correlated with chemical stability. When the Li2CO3-TiO2 ratio is reduced (e.g., Example 15 2:1 vs Example 18 4:1), the TiO2 ratio increases, and the surface layer thickness needs to be increased from 10nm to 11nm to balance the reinforcement effect and coating uniformity. When the composition is replaced (Example 19 LiF-MgO, Li2CO3-CeO2), the thickness is still maintained in the baseline range of 8nm~10nm because the density is close to that of the original system.

[0127] Thickness design logic: The coating thickness is adapted to the nanowire size and the solid content of the subsequent slurry. A thin coating (6nm for the bottom layer and 9nm for the top layer) is used to adapt to short nanowires (Example 21) to avoid hindering ion transport; a thick coating (10nm for the bottom layer and 12nm for the top layer) is used to adapt to long nanowires (Example 22) to enhance mechanical support and prevent collapse; the single-layer control group (Comparative Examples 8-9) needs to have a thickness of 18nm~19nm (close to the total thickness of the two layers) to meet the basic performance requirements and highlight the performance advantages of the two-layer structure.

[0128] Parameter uniformity: In Examples 26-33, only the deposition process was adjusted, and the coating composition and thickness were kept at the 8nm / 10nm baseline values ​​to ensure that the impact of process parameters on performance could be verified independently and to eliminate interference from composition / thickness.

[0129] Table 3 clearly shows the relationship between the solid content of the coating slurry, the deposition process, and the ionic conductivity and mechanical strength of the coating, presenting a causal chain of "process-structure-performance", as detailed below: Effect of solid content: Solid content is positively correlated with coating thickness and directly determines performance. Increasing solid content (e.g., 10% / 15% in Example 25 vs. 5% / 8% in Example 24) enhances slurry density and increases coating mechanical strength from 250 MPa to 350 MPa, but reduces ionic conductivity from 7.5 × 10⁻⁶. -6 S / cm decreased to 5.0×10 -6 S / cm; Too low a solid content can lead to porous coatings and insufficient strength, while too high a content can hinder ion transport. 8% / 12% is the optimal solid content.

[0130] The first deposition process had the following effects: both deposition temperature and cycle time were positively correlated with coating density. Increased temperature (Example 29: 210℃ vs. Example 28: 140℃) or longer cycle time (Example 26: 100s vs. Example 27: 50s) resulted in more complete solvent evaporation, leading to improved coating density. Mechanical strength increased from 265 MPa to 295 MPa, and ionic conductivity increased from 5.5 × 10⁻⁶. -6 S / cm decreased to 5.4×10 -6 S / cm; The coating is extremely dense in the ultra-low temperature long cycle (Example 28), but is prone to minor defects in the ultra-high temperature short cycle (Example 29), resulting in a slight decrease in performance.

[0131] The effects of the second deposition process are consistent with those of the first deposition process, but have a more significant impact on surface properties. Increased temperature (Example 33 230℃ vs. Example 32 170℃) or extended deposition period (Example 30 150 s vs. Example 31 80 s) leads to increased surface density, with mechanical strength increasing from 255 MPa to 315 MPa and ionic conductivity increasing from 6.3 × 10⁻⁶. -6 S / cm decreased to 5.0×10 -6 S / cm; Low temperature and long cycle surface is loose, with the best electrical conductivity but the lowest strength, while high temperature and short cycle surface is dense, with high strength but low electrical conductivity.

[0132] Disadvantages of the control group: Monolayer control group (Comparative Examples 8-9) ionic conductivity (4.2×10⁻⁶) -6 S / cm, 3.5×10 -6 The S / cm and mechanical strength (240MPa, 220MPa) are significantly lower than those of the double-layer embodiment, demonstrating the synergistic advantages of the double-layer coating's "ion conduction + mechanical support".

[0133] Table 4 focuses on the selection and concentration design of electrolyte lithium replenishment agents, highlighting the optimization direction of lithium replenishment agents for battery performance, as detailed below: Effect of lithium replenishment concentration on the same type of lithium replenisher: Taking LiBOB as an example, the performance is best when the concentration is between 0.1 mol / L and 0.15 mol / L (Example 1: 0.1 mol / L, Example 34: 0.15 mol / L), corresponding to an initial coulombic efficiency of 88.5% to 93.1% and a cycle retention rate of 83.8% to 86.2%. If the concentration is too low (Example 35: 0.05 mol / L, Example 38: 0.03 mol / L), the lithium replenishment is insufficient, and the cycle retention rate drops to 79.5% to 81.4%. If the concentration is too high (Example 39: 0.2 mol / L), the excess lithium can easily cause side reactions, and the performance improvement slows down.

[0134] Performance differences among different types of lithium replenishers: LiBOB showed the best lithium replenishment effect, with initial coulombic efficiencies exceeding 88% in Examples 1, 34, and 39; Lithium formate (Example 36, 90.2%) and LiFSI (Example 40, 85.6%) performed second best; Li2CO3 (Example 37, 87.5%) had low lithium replenishment activity, with a cycle retention rate of only 77.3%; Lithium metal powder (Example 41, 86.3%) was of mass concentration, had poor dispersibility, the lowest cycle retention rate (69.2%), and was prone to safety risks.

[0135] Concentration uniformity: All non-LiBOB lithium supplements use a 0.1 mol / L standard concentration to ensure that the effect of different types of lithium supplements on performance can be compared independently, eliminating concentration interference.

[0136] Table 5 compares the core comparative examples and the overall performance of the comparative examples, highlighting the superiority of the "nanowire array + double-layer modified coating + LiBOB lithium supplementation" technical solution of this application, as detailed below: Performance consistency of the examples: The performance of Examples 1-2 is in the excellent range, with an initial coulombic efficiency of 87.2%~88.5%, a cycle retention rate of 85.5%~86.2%, a needle penetration rate of 100%, and a low temperature retention rate of 71.5%~72.3%. There are no obvious performance shortcomings, which proves the stability of the benchmark technical solution.

[0137] Significant differences in safety performance: The needle penetration pass rate in the example was 100%, while the highest pass rate in the control group was only 80% (Comparative Example 3) and the lowest was 20% (Comparative Example 1), proving that the double-layer modified coating has a decisive effect on improving battery safety and can effectively suppress thermal runaway after puncture.

[0138] Table 6 corresponds to the etching parameters in Table 1, showing the impact of nanowire size on battery performance. The core principles are as follows: The suitability of nanowire size to performance: The best performance is achieved when the nanowire size is moderate (Example 3 110nm~130nm / 2.8μm~3.2μm), with an initial coulombic efficiency of 90.3% and a cycle retention rate of 85.2%; when the size is too small (Example 8 60nm~80nm / 0.7μm~1.1μm), the three-dimensional structure is weak, and the cycle retention rate drops to 72.3%; when the size is too large (Example 9 140nm~160nm / 5.2μm~5.8μm), the array gaps are easily blocked, and the cycle retention rate is 80.4%, which is slightly lower than that of the moderate size group.

[0139] Advantages of the parameter range: Examples 3-7 and 10-11, corresponding to the temperature range within the parameter range (25℃~80℃), exhibit superior performance with an initial coulombic efficiency of 86.2%~91.2% and a cycle retention rate of 75.1%~85.2%; performance decreases slightly at temperatures outside the parameter range (Example 8 20℃, Example 9 90℃), with a cycle retention rate of 72.3%~80.4%, thus supporting the scientific validity of the parameter range.

[0140] Low-temperature performance stability: The low-temperature retention rate of all examples reached 68.3%~74.2%, which was significantly higher than that of the comparative group in Table 5 (48.2%~65.2%), proving that nanowire arrays can increase specific surface area, optimize ion transport, and improve low-temperature adaptability.

[0141] Table 7 corresponds to the coating parameters in Table 2-3, showing the impact of coating composition, thickness, and process on battery performance. The core principles are as follows: The effect of optimizing the coating composition ratio: the performance is optimal when the proportion of LiF in the bottom layer is moderate and the proportion of TiO2 in the top layer is moderate. In Example 12 (LiF-Al2O3 4:1, Li2CO3-TiO2 3:1), the initial coulombic efficiency is 92.5% and the cycle retention rate is 85.2%. When the proportion of LiF is too high or too low, or the proportion of TiO2 is too high or too low, the performance will decrease slightly. For example, in Example 17 (LiF-Al2O3 5:1), the initial coulombic efficiency is 87.6% and the cycle retention rate is 79.4%.

[0142] The balancing effect of coating thickness: the performance is best when the thickness is moderate (8nm / 10nm), with a cycle retention rate of 80.6%~85.7% in Examples 26-33; the thickness is too thin (6nm / 9nm in Example 21) with insufficient strength, and a cycle retention rate of 77.2%; the thickness is too thick (10nm / 12nm in Example 22) which hinders ion transport, and a cycle retention rate of 82.8%, all of which are lower than the baseline thickness group.

[0143] Fine-tuning effect of deposition process: When only the deposition process is adjusted, the performance fluctuation is small (initial coulombic efficiency 87.8%~92.1%, cycle retention rate 79.8%~85.7%), proving that the process parameters can be adapted to different production needs without changing the core performance; the single-layer control group (comparative examples 8-9) has a significant performance disadvantage, further verifying the technical advantages of the double-layer coating.

[0144] Table 8 corresponds to the lithium replenisher parameters in Table 4, showing the impact of lithium replenisher type and concentration on battery performance. The core principles are as follows: The optimal concentration range for lithium supplementation agent: The best performance was achieved at a LiBOB concentration of 0.15 mol / L (Example 34), with an initial coulombic efficiency of 93.1% and a low-temperature retention rate of 74.5%, which were the highest among all examples. When the concentration was increased to 0.2 mol / L (Example 39), the performance decreased slightly (initial coulombic efficiency of 91.6%), and when the concentration was decreased to 0.03 mol / L (Example 38), the performance further declined (cycle retention rate of 81.4%). It is clear that 0.1 mol / L to 0.15 mol / L is the optimal concentration range for LiBOB.

[0145] The performance ranking of lithium replenishing agents, from best to worst, is as follows: LiBOB (0.15 mol / L) > LiBOB (0.2 mol / L) > Lithium formate > LiBOB (0.1 mol / L) > Li2CO3 > LiBOB (0.05 mol / L) > LiBOB (0.03 mol / L) > LiFSI > Lithium metal powder. Among them, LiBOB-type examples have the best overall performance and are the optimal lithium replenishing agent selection.

[0146] Matching performance with lithium replenishment requirements: Initial coulombic efficiency is positively correlated with the activity of the lithium replenishment agent; the higher the lithium replenishment activity, the smaller the initial irreversible capacity loss. Cycle retention is positively correlated with the stability of the lithium replenishment agent; LiBOB has the best stability and the highest cycle retention, while lithium metal powder has the worst stability and the lowest cycle retention (69.2%). Summary of core common laws The core technology solution of this application (nanowire array + double-layer modified coating + LiBOB lithium replenishment) can achieve a comprehensive performance improvement of the battery. The performance of each embodiment is significantly better than that of the comparison group, which solves the safety shortcomings of traditional lithium metal batteries.

[0147] Each parameter has an optimal range, and deviating from the range will lead to performance degradation. For example, etching temperature is 25℃~80℃, coating thickness is 5nm~10nm for the bottom layer and 8nm~12nm for the surface layer, and LiBOB concentration is 0.1mol / L~0.15mol / L. Parameter design needs to take into account both "functional adaptation" and "performance balance".

[0148] There is a synergistic effect among the technical features: the nanowire array provides three-dimensional support, the double coating optimizes ion conduction and mechanical strength, and LiBOB supplements the lithium source. The performance improvement effect of the combination of the three is greater than the sum of individual features, which is the core reason for the excellent performance of the embodiment.

[0149] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A lithium metal battery, characterized in that, It includes a positive electrode sheet, a separator, a negative electrode current collector, and an electrolyte; the negative electrode current collector includes a carrier and a modified coating disposed on at least one surface of the carrier; The surface of the carrier has a nanowire array; The modified coating comprises a bottom layer and a top layer stacked together, the bottom layer comprising a nucleation promoter and a reinforcing agent, and the top layer comprising an interface passivator and a structure stabilizer; The electrolyte includes a lithium supplement.

2. The lithium metal battery according to claim 1, characterized in that, The nanowires in the nanowire array have a diameter of 50nm~200nm and a length of 1μm~5μm.

3. The lithium metal battery according to claim 1, characterized in that, The nucleation promoter includes at least one of lithium fluoride, lithium nitride and lithium oxide; And / or, the reinforcing agent includes at least one of aluminum oxide, magnesium oxide and zirconium oxide; And / or, the interface passivating agent includes at least one of lithium carbonate, lithium metaphosphate, and lithium sulfate; And / or, the structural stabilizer includes at least one of titanium oxide, cerium oxide, and aluminum oxide.

4. The lithium metal battery according to claim 1, characterized in that, The mass ratio of the nucleation promoter to the reinforcing agent is (3~5):1; And / or, the mass ratio of the interface passivating agent to the structure stabilizer is (2~4):

1.

5. The lithium metal battery according to claim 1, characterized in that, The thickness of the modified coating is 13nm~22nm; wherein: The thickness of the bottom layer is 5nm to 10nm; and / or the thickness of the top layer is 8nm to 12nm.

6. The lithium metal battery according to claim 1, characterized in that, The ionic conductivity of the SEI film in the lithium metal battery is greater than or equal to 5 × 10⁻⁶. -6 S / cm; And / or, the mechanical strength of the SEI film of the lithium metal battery is greater than or equal to 250 MPa.

7. The lithium metal battery according to claim 1, characterized in that, The lithium supplement includes at least one of lithium dioxaborate, lithium formate, and lithium carbonate. And / or, the molar concentration of the lithium supplement in the electrolyte is 0.05 mol / L to 0.15 mol / L.

8. A method for preparing a lithium metal battery according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Immerse the carrier in an etching solution for etching treatment to obtain a carrier with a nanowire array on the surface; S2. A first deposition process and a second deposition process are sequentially performed on the surface of the carrier after etching in step S1 to obtain a negative electrode current collector; a modified coating is formed on the surface of the carrier. Wherein, the first coating slurry of the first deposition treatment includes a nucleation promoter and a reinforcing agent; the second coating slurry of the second deposition treatment includes an interface passivator and a structure stabilizer; S3. Inject electrolyte into the cell including the negative electrode current collector to obtain the lithium metal battery, wherein the electrolyte includes a lithium replenishing agent.

9. The method for preparing a lithium metal battery according to claim 8, characterized in that, Step S1 specifically includes: immersing the copper substrate in an etching solution containing alkaline salts for etching treatment; Wherein, the alkaline salt includes at least one of sodium hydroxide, potassium hydroxide and sodium carbonate; and / or, the molar concentration of the etching solution is 0.5 mol / L to 2 mol / L; And / or, the etching temperature of the etching process is 25℃~80℃, and the etching time is 30min~120min.

10. The method for preparing a lithium metal battery according to claim 8, characterized in that, The first coating slurry has a solid content of 5% to 10%; and / or, the second coating slurry has a solid content of 8% to 15%. And / or, the deposition temperature of the first deposition treatment is 150℃~200℃, and the deposition period is 50s~100s; and / or, the deposition temperature of the second deposition treatment is 180℃~220℃, and the deposition period is 80s~150s.

Images