A vacuum evaporation magnesium film, a preparation method and application thereof

Abstract

The present application relates to the technical field of magnesium foil material, in particular to a vacuum evaporation magnesium film, a preparation method and application thereof, the magnesium film comprises a substrate and a thin film layer, the material of the thin film layer is magnesium and is covered on the surface of the substrate by vacuum evaporation; the preparation method uses aluminum foil, copper foil, gold foil, silver foil, nickel foil, molybdenum foil, titanium foil, tin foil, stainless steel foil, polymer composite metal foil, metal alloy foil, carbon-coated metal foil, polyimide and high polymer material as the substrate, a layer of high-purity magnesium thin film is uniformly deposited on the surface of the substrate by controlling the vacuum evaporation process; when the magnesium film is applied to a magnesium battery, the substrate provides good electrical conductivity and mechanical support, and the magnesium layer directly participates in the electrochemical reaction as an active material, which not only improves the energy density and cycle life of the magnesium battery, but also simplifies the manufacturing process and reduces the cost; the magnesium negative electrode prepared by the method has excellent electrochemical performance and stability, and has good application prospect.

Description

Technical Field

[0001] This invention relates to the field of magnesium foil material technology, specifically to a method for preparing a vacuum-deposited magnesium film and its application in magnesium batteries. Background Technology

[0002] With the rapid development of portable electronic devices, electric vehicles, and energy storage systems, the demand for high-performance rechargeable batteries is increasing. While traditional lithium-ion batteries are widely used, safety concerns and resource constraints have prompted researchers to seek more ideal alternatives. Magnesium batteries have attracted widespread attention due to their large theoretical capacity, low cost, and resistance to the formation of dangerous dendritic structures.

[0003] In magnesium battery systems, the current collector is one of the key components connecting the external circuitry and the internal electrode materials. Ideally, it should possess excellent electrical conductivity, sufficient mechanical strength, and good chemical compatibility.

[0004] For magnesium batteries, using magnesium as the negative electrode material is a natural choice. However, due to the inherent properties of magnesium, preparing very thin magnesium foil presents a series of challenges. While traditional rolling technology can produce magnesium foil of a certain thickness, the cost increases significantly when achieving the ultra-thin specifications required for batteries. Furthermore, the rolling process can easily generate material stress, affecting the quality, consistency, and uniformity of the final product.

[0005] In addition, electrodeposition is also an effective method for preparing magnesium foil. However, the preparation of magnesium foil by electrodeposition is prone to introducing impurities, resulting in low purity; it requires the use of chemical solutions, which may cause environmental pollution; and it has certain limitations on the shape and type of substrate material, making it unsuitable for complex-shaped substrates.

[0006] In addition, vapor-deposited aluminum films have been widely used in fields such as packaging, construction and electronics. However, compared with magnesium, Al has a higher boiling point (2470℃) and a higher latent heat of vaporization (10500kJ / kg), while magnesium has a lower boiling point (1092℃) and a lower latent heat of vaporization (5200kJ / kg). At the same time, magnesium has a lower density than aluminum and better electromagnetic shielding capabilities, which makes magnesium an indispensable material for lightweighting and electromagnetic shielding. Summary of the Invention

[0007] The present invention aims to provide a vacuum-deposited magnesium film, which can be applied to multiple fields, especially the field of magnesium batteries, to improve the uniformity of the magnesium film.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a vacuum-deposited magnesium film, comprising a substrate and a thin film layer, wherein the thin film layer is coated on the surface of the substrate by vacuum evaporation, and the material of the thin film layer is magnesium.

[0009] Preferably, as an improvement, the substrate is one or more of the following: aluminum foil, copper foil, gold foil, silver foil, nickel foil, molybdenum foil, titanium foil, tin foil, stainless steel foil, metal alloy foil, polymer composite metal foil, carbon-coated metal foil, polyimide, or polymer materials.

[0010] Preferably, as an improvement, the thickness of the thin film layer is 0.001μm-30μm.

[0011] This invention also provides a method for preparing a magnesium film by vacuum evaporation, comprising the following steps:

[0012] S1. Substrate pretreatment: The substrate is subjected to ultrasonic cleaning and plasma etching;

[0013] S2. Vacuum Environment Establishment: Evacuate the coating chamber to a vacuum level of 9×10⁻⁶. -6 -5×10 -1 Pa, then argon gas was introduced, and then the vacuum level of the coating chamber was evacuated again to 9 × 10⁻⁶. -6 -5×10 -2 Pa;

[0014] S3. Substrate loading: Fix the substrate onto the base plate and place the magnesium material in the evaporation boat;

[0015] S4. Evaporation Process: Heat the evaporation boat to 50-1800℃, control the substrate temperature to room temperature -300℃, and rotate it at a speed of ≤25 rpm, maintaining the deposition rate at...

[0016] Preferably, as an improvement, the argon purity is ≥99.99%, the distance between the evaporation boat and the substrate is 200-600 mm, and the thickness of the magnesium film is 0.001 μm-30 μm.

[0017] Preferably, as an improvement, step S4 further includes depositing elemental In, Sn, Bi, Sb, Si, Ge, Ga, Se, Ag, Au, Te and their 2-11 elemental alloys, or organic / inorganic compounds on the magnesium film obtained by vapor deposition, with a composite layer thickness of 0.001 μm-6 μm.

[0018] Preferably, as an improvement, the magnesium material placed on the evaporation boat is a magnesium rod, magnesium wire, or magnesium granules.

[0019] The present invention also provides an application of vacuum-deposited magnesium film, which is applied to magnesium batteries.

[0020] Preferably, as an improvement, the thickness of the magnesium film is 9 μm.

[0021] The technical advantages of this solution are: vapor-deposited magnesium films can be applied in multiple fields. In the field of magnesium batteries, compared with metal-rolled magnesium films, the magnesium films prepared by vacuum evaporation in this solution have higher uniformity and exhibit excellent long-term cycle stability and low overpotential. At the same time, it has the advantages of being environmentally friendly, low-cost, and simple in preparation process, and has a very good application prospect.

[0022] Furthermore, while electrodeposition can also prepare magnesium films, it easily introduces impurities, resulting in lower purity. Electrodeposition also requires chemical solutions, potentially causing environmental pollution, and has limitations on the shape and type of substrate material, making it unsuitable for complex-shaped substrates. In contrast, vacuum evaporation for preparing magnesium films on copper foil offers higher purity, better uniformity, and stronger bonding strength compared to electrodeposition and rolling methods. Because this method is performed in a vacuum environment, it reduces the introduction of impurities and oxides, allows for precise control of deposition rate and thickness, is suitable for complex-shaped substrates, and avoids chemical pollution, making it suitable for large-scale industrial production. These advantages make vacuum evaporation more competitive in applications requiring high purity, high uniformity, and high bonding strength.

[0023] In addition, research on the application of vacuum evaporation in the field of magnesium batteries is relatively scarce. This is due to the challenges brought about by the inherent characteristics of magnesium battery technology and the specific difficulties encountered when applying vacuum evaporation in this field.

[0024] Compared to traditional batteries, magnesium battery technology faces several bottlenecks that urgently need to be overcome. Firstly, magnesium ions are chemically reactive and readily react with electrolytes during charging and discharging, generating various complex compounds. This not only reduces the battery's energy conversion efficiency but also affects its cycle life. For example, magnesium metal anodes can form uneven passivation films in certain electrolytes, leading to increased internal resistance and decreased charge-discharge performance. This unstable chemical reaction characteristic necessitates more careful consideration of process conditions when preparing magnesium battery materials using vacuum evaporation methods to avoid unnecessary reactions between the materials and trace impurities in the environment, undoubtedly increasing the difficulty of process control.

[0025] Secondly, the selection of electrode materials for magnesium batteries is limited, and their performance needs improvement. Currently common electrode materials often fail to achieve efficient ion insertion and extraction during interaction with magnesium ions, resulting in low battery capacity. For example, when some transition metal oxides are used as magnesium battery materials, the large radius of magnesium ions leads to a slow diffusion rate in the crystal lattice, limiting the battery's charge / discharge rate. Vacuum evaporation, on the other hand, has a unique impact on the atomic structure and surface properties of electrode materials.

[0026] From the perspective of applying vacuum evaporation in magnesium batteries, there are also specific challenges. Firstly, magnesium has a relatively high melting point of 650℃ and a boiling point of 1090℃, requiring even higher temperatures to evaporate it during the vacuum evaporation process. This high-temperature environment not only places extremely high demands on the evaporation equipment, increasing costs, but may also lead to decreased stability during long-term operation. Secondly, the evaporation rate of magnesium at high temperatures is difficult to control precisely. Unstable evaporation rates can affect the uniformity of magnesium deposition on the substrate, thus impacting the performance of the battery electrodes.

[0027] On the other hand, magnesium thin films prepared by vacuum evaporation face challenges in terms of compatibility with other battery components. Magnesium batteries typically require electrodes, electrolytes, separators, and other components to work together, but the surface properties of magnesium thin films prepared by vacuum evaporation may not be compatible with traditional electrolytes and separators. For example, the microstructure of the film surface may hinder electrolyte wetting, leading to impeded ion transport and affecting the overall performance of the battery.

[0028] This innovative approach proposes a vacuum evaporation method for preparing magnesium films. By controlling the preparation method and film thickness, a magnesium film is formed by covering the substrate surface with a magnesium layer, creating a Cu@Mg integrated electrode. Compared to rolled magnesium films, this electrode exhibits superior long-term cycle stability and lower overpotential. The material preparation process is simple, low-cost, and suitable for large-scale industrial production. Vacuum evaporation avoids internal stress caused by machining, improving the mechanical stability and durability of the finished product. Evaporation in a high-vacuum environment effectively prevents the incorporation of oxides and other impurities, ensuring the purity of the magnesium film. The copper foil acts as a current collector, providing a good conductive path, while the magnesium layer directly participates in the electrochemical reaction. This composite structure helps improve the cycle life of magnesium batteries. Attached Figure Description

[0029] Figure 1 The images show the SEM cross-section and planar scan of a 9 μm thick magnesium foil prepared by vacuum evaporation in Example 1 of this invention.

[0030] Figure 2 In Embodiment 2 of the present invention, under high current density (2mA / cm²), 2 -2mAh / cm 2 A comparison of charge-discharge curves of rolled magnesium foil and vapor-deposited magnesium foil of the present invention applied to symmetrical batteries;

[0031] Figure 3 This is Example 3 of the present invention at 0.2mA cm -2 0.2mAh cm -2 Nucleation overpotential curves of rolled magnesium foil and Cu@Mg under the specified conditions;

[0032] Figure 4 In Embodiment 4 of the present invention, at 1mA cm -2 1mAh cm -2 Nucleation overpotential curves of rolled magnesium foil and Cu@Mg under the specified conditions;

[0033] Figure 5 In embodiment 5 of the present invention, at 0.2 mA cm -2 Charge-discharge curves of Mg / / Cu and Cu@Mg / / Cu half-cells in the first cycle under the given conditions;

[0034] Figure 6 This refers to the contact angle of the APC electrolyte on rolled magnesium foil and Cu@Mg in Example 6 of the present invention;

[0035] Figure 7 This is the AFM potential difference diagram of the polished rolled magnesium foil and Cu@Mg in Example 7 of the present invention;

[0036] Figure 8 In Example 8 of this invention, the rolled magnesium and modified magnesium are at a temperature of 0.01 mA / cm. -2 0.005mAhcm -2 Time-voltage curves in 0.5M Mg(TFSI)2in DME electrolyte under the specified conditions;

[0037] Figure 9 This is a schematic diagram of a vacuum evaporation coating equipment.

[0038] Figure 10 Images showing the effect of magnesium deposition on a copper substrate before and after the deposition process. Detailed Implementation

[0039] The following detailed description illustrates the specific implementation method:

[0040] This specific embodiment provides a vacuum-deposited magnesium film, including a substrate and a thin film layer. The thin film layer is deposited onto the surface of the substrate using a vacuum evaporation method, achieving the following effect: Figure 10 As shown, the material of the thin film layer is magnesium. In this document, thin film layer, magnesium film, and magnesium foil have the same meaning, and the thickness is 0.001μm-30μm.

[0041] The substrate is one or more of the following: aluminum foil, copper foil, gold foil, silver foil, nickel foil, molybdenum foil, titanium foil, tin foil, stainless steel foil, metal alloy foil, polymer composite metal foil, carbon-coated metal foil, polyimide, or polymer materials.

[0042] This specific embodiment also includes a method for preparing a magnesium film by vacuum evaporation, comprising the following steps:

[0043] S1. Substrate pretreatment: The substrate is subjected to ultrasonic cleaning and plasma etching;

[0044] S2. Vacuum Environment Establishment: Evaporate the vacuum chamber of the vacuum evaporation coating equipment to a vacuum level of 9×10⁻⁶. -6 -5×10 - 1 Pa, then argon gas with a purity ≥99.99% was introduced, and the vacuum level of the coating chamber was then evacuated to 9×10⁻⁶. -6 -5×10 -2 Pa;

[0045] S3. Substrate Loading: The substrate is adhered to, as shown in... Figure 9 The vacuum chamber of the vacuum evaporation coating equipment shown is located on the lower surface of the metal substrate. The evaporation boat is located below the substrate, and the distance between the evaporation boat and the substrate is 200-600mm. Magnesium rods / magnesium wires / magnesium particles are placed on the evaporation boat.

[0046] S4. Evaporation Process: Heat the evaporation boat to 50-1800℃, control the substrate temperature to room temperature -300℃, and rotate it at a speed of ≤25 rpm, maintaining the deposition rate at...

[0047] It also includes the steps of depositing elemental In, Sn, Bi, Sb, Si, Ge, Ga, Se, Ag, Au, Te and their 2-11 elemental alloys, and organic / inorganic compounds on the magnesium film obtained by S4 evaporation, with the thickness of the deposited composite layer being 0.001 μm-6 μm.

[0048] The aforementioned magnesium foil can be used in magnesium batteries, and the magnesium film thickness used in magnesium batteries is preferably 9μm.

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0050] Example 1

[0051] This embodiment proposes a magnesium foil, including a copper foil and a thin film layer. The thin film layer is coated on the surface of the substrate by vacuum evaporation, and the material of the thin film layer is magnesium.

[0052] The magnesium foil proposed in this embodiment is prepared by the following steps: fixing copper foil onto the metal substrate of the vacuum chamber of a vacuum evaporation coating equipment; placing magnesium rods / magnesium wires / magnesium particles onto an evaporation boat; and using a molecular pump and other auxiliary systems to evaporate the coating chamber to a vacuum level ≤5×10⁻⁻¹. 1 Pa, then argon gas was introduced, and then the vacuum degree of the coating chamber was evacuated again to ≤5×10- 2 Pa; Heat the crucible to 50-1800℃, control the substrate temperature to room temperature-300℃, and rotate it at a speed of 0-25 rpm, maintaining the deposition rate at [missing value]. Figure 1 This is a SEM scan of a 9μm thick magnesium film prepared by vacuum evaporation.

[0053] The following examples demonstrate experiments on the application of magnesium foil in the field of magnesium batteries.

[0054] Example 2

[0055] This embodiment proposes a magnesium foil, including a copper foil and a thin film layer. The thin film layer is coated on the surface of the substrate by vacuum evaporation, and the material of the thin film layer is magnesium.

[0056] The magnesium foil proposed in this embodiment is prepared by the following steps: fixing copper foil onto the metal substrate of the vacuum chamber of a vacuum evaporation coating equipment; placing magnesium rods / magnesium wires / magnesium particles on an evaporation boat; and using a molecular pump and other auxiliary systems to evaporate the vacuum degree of the coating chamber to ≤5×10⁻⁻¹. 1 Pa, then argon gas was introduced, and then the vacuum degree of the coating chamber was evacuated again to ≤5×10- 2 Pa; Heat the crucible to 50-1800℃, control the substrate temperature to room temperature-300℃, and rotate it at a speed of 0-25 rpm, maintaining the deposition rate at [missing value].

[0057] The magnesium-coated copper foil prepared in this embodiment was placed in an argon glove box with a water and oxygen value of less than 1 ppm. Copper foils with different magnesium coating thicknesses obtained in this example were used as positive and negative electrodes, respectively. Rolled magnesium foil was used as positive and negative electrodes. GF / A glass fiber membrane was used as the separator, and 100 μL of APC electrolyte was used as the electrolyte. The CR2032 button cell was assembled in the following order: negative electrode shell → negative electrode sheet → separator → electrolyte → positive electrode sheet → gasket → spring piece.

[0058] The battery was subjected to constant current charge-discharge testing using the Xinwei Battery Testing System at a temperature of 30℃. The test conditions were a current density of 2 mA / cm². 2 The charging and discharging process is time-controlled, with each charge and discharge lasting 1 hour, and a 30-second interval between each charge and discharge cycle, repeated 9999 times. This yields results at a high current density (2 mA / cm²). 2 -2mAh / cm 2 Charge-discharge curves of symmetrical batteries with rolled magnesium foil and copper foil covered with 9μm magnesium are shown in the figure. Figure 2 As shown.

[0059] Symmetrical cells composed of rolled magnesium foil and copper foil covered with 9μm magnesium each achieve a current of 2mA / cm. 2 Constant current charge-discharge tests were performed at current density, such as... Figure 2As shown, it can be clearly observed that during the long-term charge-discharge cycle within 800 hours, the copper foil covered with magnesium exhibited a significant reduction in overpotential compared to the rolled magnesium foil. The overpotential of the copper foil covered with magnesium was significantly lower than that of the symmetrical cell assembled with the rolled magnesium foil. Furthermore, the symmetrical cell assembled with the rolled magnesium foil experienced a short circuit at around 630 hours. This indicates that the copper foil covered with magnesium is beneficial for the uniform deposition of Mg ions and helps to improve the cycle life of magnesium-ion batteries.

[0060] Example 3

[0061] This embodiment proposes a magnesium foil, including a copper foil and a thin film layer. The thin film layer is coated on the surface of the substrate by vacuum evaporation, and the material of the thin film layer is magnesium.

[0062] The magnesium foil proposed in this embodiment is prepared by the following steps: fixing copper foil onto the metal substrate of the vacuum chamber of a vacuum evaporation coating equipment; placing magnesium rods / magnesium wires / magnesium particles on an evaporation boat; and using a molecular pump and other auxiliary systems to evaporate the vacuum degree of the coating chamber to ≤5×10⁻⁻¹. 1 Pa, then argon gas was introduced, and then the vacuum degree of the coating chamber was evacuated again to ≤5×10- 2 Pa; Heat the crucible to 50-1800℃, control the substrate temperature to room temperature-300℃, and rotate it at a speed of 0-25 rpm, maintaining the deposition rate at [missing value].

[0063] The magnesium-coated copper foil prepared in this embodiment was placed in an argon glove box with a water and oxygen value of less than 1 ppm. The magnesium-coated copper foil and rolled magnesium foil obtained in this example were used as negative electrodes, and the copper foil was used as positive electrode. The separator was a GF / A glass fiber separator, and the electrolyte was a total of 100 μL APC electrolyte. The CR2032 button cell was assembled in the following order: negative electrode shell → negative electrode sheet → separator → electrolyte → positive electrode sheet → gasket → spring piece.

[0064] The nucleation overpotential of the battery was tested using the Xinwei battery testing system at a temperature of 30℃. The test conditions were a current density of 0.2 mA / cm². 2 The discharge time is 1 hour.

[0065] like Figure 3 As shown, with current density and areal capacitance of 0.2 mA cm⁻¹ -2 0.2mAh cm -2At that time, the nucleation overpotential of Cu@Mg was 0.155V, while the nucleation overpotential of rolled magnesium foil was as high as 0.949V. The nucleation overpotential of Cu@Mg was significantly lower than that of rolled magnesium foil, indicating that the Cu@Mg anode has a lower nucleation energy barrier and better magnesium affinity. Cu@Mg improves the overall electrochemical activity of the magnesium anode, provides nucleation sites for magnesium deposition, and promotes nucleation and uniform growth.

[0066] Example 4

[0067] This embodiment proposes a magnesium foil, including a copper foil and a thin film layer. The thin film layer is coated on the surface of the substrate by vacuum evaporation, and the material of the thin film layer is magnesium.

[0068] The magnesium foil proposed in this embodiment is prepared by the following steps: fixing copper foil onto the metal substrate of the vacuum chamber of a vacuum evaporation coating equipment; placing magnesium rods / magnesium wires / magnesium particles on an evaporation boat; and using a molecular pump and other auxiliary systems to evaporate the vacuum degree of the coating chamber to ≤5×10⁻⁻¹. 1 Pa, then argon gas was introduced, and then the vacuum degree of the coating chamber was evacuated again to ≤5×10- 2 Pa; Heat the crucible to 50-1800℃, control the substrate temperature to room temperature-300℃, and rotate it at a speed of 0-25 rpm, maintaining the deposition rate at [missing value].

[0069] The magnesium-coated copper foil prepared in this embodiment was placed in an argon glove box with a water and oxygen value of less than 1 ppm. The magnesium-coated copper foil and rolled magnesium foil obtained in this example were used as negative electrodes, and the copper foil was used as positive electrode. The separator was a GF / A glass fiber separator, and the electrolyte was a total of 100 μL APC electrolyte. The CR2032 button cell was assembled in the following order: negative electrode shell → negative electrode sheet → separator → electrolyte → positive electrode sheet → gasket → spring piece.

[0070] The nucleation overpotential of the battery was tested using the Xinwei battery testing system at a temperature of 30℃. The test conditions were a current density of 1 mA / cm². 2 The discharge time is 1 hour. For example... Figure 4 As shown, when the current density and areal capacitance increase to 1 mA cm⁻¹ -2 1mAh cm -2 At that time, the nucleation overpotential of rolled magnesium foil (0.860V) was still higher than that of Cu@Mg (0.561V). In both sets of nucleation overpotential tests, the nucleation overpotential of Cu@Mg was significantly lower than that of rolled magnesium foil, indicating that the Cu@Mg anode has a lower nucleation energy barrier and better magnesium affinity. Cu@Mg improves the overall electrochemical activity of the magnesium anode, provides nucleation sites for magnesium deposition, and promotes nucleation and uniform growth.

[0071] Example 5

[0072] This embodiment proposes a magnesium foil, including a copper foil and a thin film layer. The thin film layer is coated on the surface of the substrate by vacuum evaporation, and the material of the thin film layer is magnesium.

[0073] The magnesium foil proposed in this embodiment is prepared by the following steps: fixing copper foil onto the metal substrate of the vacuum chamber of a vacuum evaporation coating equipment; placing magnesium rods / magnesium wires / magnesium particles on an evaporation boat; and using a molecular pump and other auxiliary systems to evaporate the vacuum degree of the coating chamber to ≤5×10⁻⁻¹. 1 Pa, then argon gas was introduced, and then the vacuum degree of the coating chamber was evacuated again to ≤5×10- 2 Pa; Heat the crucible to 50-1800℃, control the substrate temperature to room temperature-300℃, and rotate it at a speed of 0-25 rpm, maintaining the deposition rate at [missing value].

[0074] The magnesium-coated copper foil prepared in this embodiment was placed in an argon glove box with a water and oxygen value of less than 1 ppm. The magnesium-coated copper foil obtained in this example was used as the positive and negative electrodes, respectively. The rolled magnesium foil was used as the positive and negative electrodes. The separator was a GF / A glass fiber separator, and the electrolyte was a total of 100 μL APC electrolyte. The CR2032 button cell was assembled in the following order: negative electrode shell → negative electrode sheet → separator → electrolyte → positive electrode sheet → gasket → spring piece.

[0075] At a temperature of 30℃, the rolled magnesium foil and Cu@Mg half-cells were tested using the Xinwei Battery Testing System at a current density of 0.2 mA cm⁻¹. -2 A constant current charge-discharge test was conducted under the following conditions: each charge-discharge cycle lasted 1 hour, the charging cutoff voltage was 1V, and there was a 30-second pause between each charge-discharge cycle.

[0076] The charge-discharge curves of Mg / / Cu and Cu@Mg / / Cu half-cells under different cycles are shown below. Figure 5 As shown, in the APC electrolyte, both rolled magnesium foil and vapor-deposited magnesium film anodes exhibit a certain activation process in the initial stage of cycling. The first-cycle overpotential of Cu@Mg / / Cu is 238mV, lower than the 342mV of the Mg / / Cu half-cell. This indicates that the introduction of the Cu substrate in the vapor-deposited magnesium foil facilitates the interaction between Mg and Mg. 2+ The low energy barrier for deposition / dissolution during the initial phase transition results in a low voltage hysteresis in the first cycle.

[0077] Example 6

[0078] This embodiment proposes a magnesium foil, including a copper foil and a thin film layer. The thin film layer is coated on the surface of the substrate by vacuum evaporation, and the material of the thin film layer is magnesium.

[0079] The magnesium foil proposed in this embodiment is prepared by the following steps: fixing copper foil onto the metal substrate of the vacuum chamber of a vacuum evaporation coating equipment; placing magnesium rods / magnesium wires / magnesium particles on an evaporation boat; and using a molecular pump and other auxiliary systems to evaporate the vacuum degree of the coating chamber to ≤5×10⁻⁻¹. 1 Pa, then argon gas was introduced, and then the vacuum degree of the coating chamber was evacuated again to ≤5×10- 2 Pa; Heat the crucible to 50-1800℃, control the substrate temperature to room temperature-300℃, and rotate it at a speed of 0-25 rpm, maintaining the deposition rate at [missing value].

[0080] like Figure 6 The contact angle test results show that the contact angle between the rolled magnesium foil and the APC electrolyte is 45.72°, while the contact angle between the vapor-deposited magnesium foil (Cu@Mg) and the APC electrolyte is only 22.83°, much smaller than that of the rolled magnesium foil. The smaller contact angle indicates that the surface of the vapor-deposited magnesium foil (Cu@Mg) is more easily wetted by the electrolyte, which helps improve the contact efficiency between the electrolyte and the electrode material, thereby improving the battery's ion transport performance and electrochemical reaction kinetics. In contrast, the larger contact angle of the rolled magnesium foil indicates poor wettability, which may lead to increased interfacial resistance and decreased battery performance.

[0081] Example 7

[0082] This embodiment proposes a magnesium foil, including a copper foil and a thin film layer. The thin film layer is coated on the surface of the substrate by vacuum evaporation, and the material of the thin film layer is magnesium.

[0083] The magnesium foil proposed in this embodiment is prepared by the following steps: fixing copper foil onto the metal substrate of the vacuum chamber of a vacuum evaporation coating equipment; placing magnesium rods / magnesium wires / magnesium particles on an evaporation boat; and using a molecular pump and other auxiliary systems to evaporate the vacuum degree of the coating chamber to ≤5×10⁻⁻¹. 1 Pa, then argon gas was introduced, and then the vacuum degree of the coating chamber was evacuated again to ≤5×10- 2 Pa; Heat the crucible to 50-1800℃, control the substrate temperature to room temperature-300℃, and rotate it at a speed of 0-25 rpm, maintaining the deposition rate at [missing value]. from Figure 7As shown in the AFM potential difference graph, the average potential difference of the vapor-deposited magnesium film is 24.236 mV, lower than that of the rolled magnesium foil (31.958 mV). This lower potential difference indicates that the vapor-deposited magnesium film is more stable in electrochemical reactions, enabling more efficient insertion and extraction of magnesium ions, reducing polarization and energy loss, thereby improving the battery's charge-discharge efficiency and cycle stability. Simultaneously, a lower potential difference also means fewer interfacial side reactions, contributing to extended battery life. In contrast, the higher potential difference of the rolled magnesium foil may lead to greater polarization, energy loss, and side reactions, affecting battery performance and lifespan. Therefore, vapor-deposited magnesium film has a greater advantage in electrochemical performance as a negative electrode and is more suitable for high-performance battery applications.

[0084] Example 8

[0085] This embodiment proposes a magnesium foil, including a copper foil and a thin film layer. The thin film layer is coated on the surface of the substrate by vacuum evaporation, and the material of the thin film layer is magnesium.

[0086] The magnesium foil proposed in this embodiment is prepared by the following steps: fixing copper foil onto the metal substrate of the vacuum chamber of a vacuum evaporation coating equipment; placing magnesium rods / magnesium wires / magnesium particles on an evaporation boat; and using a molecular pump and other auxiliary systems to evaporate the vacuum degree of the coating chamber to ≤5×10⁻⁻¹. 1 Pa, then argon gas was introduced, and then the vacuum degree of the coating chamber was evacuated again to ≤5×10- 2 Pa; Heat the crucible to 50-1800℃, control the substrate temperature to room temperature-300℃, and rotate it at a speed of 0-25 rpm, maintaining the deposition rate at [missing value]. Subsequently, a layer of deposited InSnBi alloy was vapor-deposited onto the magnesium film.

[0087] The magnesium-coated copper foil prepared in this embodiment was placed in an argon glove box with a water and oxygen value of less than 1 ppm. The modified magnesium obtained in this example was used as the positive and negative electrodes, respectively. The rolled magnesium foil was used as the positive and negative electrodes. The separator was a GF / A glass fiber separator. The electrolyte was 100 μL of 0.5M Mg(TFSI)2in DME electrolyte. The CR2032 coin cell was assembled in the following order: negative electrode shell → negative electrode sheet → separator → electrolyte → positive electrode sheet → gasket → spring sheet.

[0088] The battery was subjected to constant current charge-discharge testing using the Xinwei battery testing system at a temperature of 30℃. The test conditions were a current density of 0.01 mA / cm². 2 The charging and discharging process is time-controlled, with each charge and discharge cycle lasting 0.5 hours. A 30-second interval is maintained between each charge and discharge cycle, for a total of 9999 cycles. Figure 8 As shown, the result was obtained at 0.01 mA / cm 20.005mAh / cm 2 Time-voltage curves of modified magnesium and rolled magnesium under the specified conditions.

[0089] Symmetrical cells composed of modified magnesium and rolled magnesium respectively have an energy density of 0.01 mA / cm². 2 Constant current charge-discharge tests at current density clearly showed that the overpotential of modified magnesium was significantly lower than that of rolled magnesium, while also exhibiting a longer cycle life. Figure 8 It can be seen that the overpotential of modified magnesium is around 0.8V, which is significantly lower than the 2V of rolled magnesium foil. In addition, the symmetrical cell composed of rolled magnesium experienced a short circuit after 280h, while the modified magnesium cell only experienced a short circuit after about 680h. The modified magnesium anode exhibits excellent deposition / dissolution cycle stability.

[0090] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A vacuum-deposited magnesium film for use in magnesium batteries, comprising a substrate and a thin film layer, wherein the thin film layer is deposited on the surface of the substrate by vacuum evaporation, the material of the thin film layer is magnesium; the substrate is copper foil; and the thickness of the thin film layer is 9μm-30μm.

2. The method for preparing a vacuum-deposited magnesium film for use in magnesium batteries according to claim 1, characterized in that: S1. Substrate pretreatment: The substrate is subjected to ultrasonic cleaning and plasma etching; S2. Vacuum Environment Establishment: Evacuate the coating chamber to a vacuum level of 9×10⁻⁶. -6 -5×10 -1 Pa, then argon gas was introduced, and then the vacuum level of the coating chamber was evacuated again to 9 × 10⁻⁶. -6 -5×10 -2 Pa; S3. Substrate loading: Fix the substrate onto the base plate and place the magnesium material in the evaporation boat; S4. Evaporation process: Heat the evaporation boat to 50-1800°C, control the substrate temperature to room temperature-300°C, and rotate at a speed of ≤25 rpm, maintaining the deposition rate at 0.1 Å / s-9999.9 Å / s.

3. The method for preparing a vacuum-deposited magnesium film for use in magnesium batteries according to claim 2, characterized in that: Argon purity ≥ 99.99%, and the distance between the evaporation boat and the substrate is 200-600 mm.

4. The method for preparing a vacuum-deposited magnesium film for use in magnesium batteries according to claim 3, characterized in that: S4 further includes the step of depositing elemental In, Sn, Bi, Sb, Si, Ge, Ga, Se, Ag, Au, Te and their 2-11 elemental alloys, and organic / inorganic compounds on the magnesium film obtained by vapor deposition, with a composite layer thickness of 0.001 μm-6 μm.

5. The method for preparing a vacuum-deposited magnesium film for use in magnesium batteries according to claim 4, characterized in that: The magnesium material placed on the evaporation boat is magnesium rod, magnesium wire, or magnesium granules.

6. The method for preparing a vacuum-deposited magnesium film for use in magnesium batteries according to claim 5, characterized in that: The magnesium film has a thickness of 9 μm.

Images