Atomic layer deposition Al2O3 film method for magnesium metal negative electrode

Abstract

The invention provides an Al2O3 thin film atomic layer deposition method for a magnesium metal negative electrode, and belongs to the technical field of magnesium metal surface treatment.The Al2O3 thin film atomic layer deposition method comprises the steps that firstly, a substrate sample is put into a reaction cavity, and vacuumizing and heating treatment are carried out; then, an aluminum precursor source is fed into the reaction cavity through carrier gas, and self-limiting chemical adsorption is carried out on the aluminum precursor source and the surface of the substrate sample; then, carrier gas is introduced for purging to remove by-products and residual aluminum sources. Afterwards, an oxygen source is fed for reaction, and then purging is carried out to complete a growth cycle. By repeating the cycle, the Al2O3 film is uniformly deposited on the substrate sample. The method for the atomic layer deposition of the Al2O3 thin film is low in cost, easy to operate, controllable in condition and good in uniformity, on one hand, the method can adapt to substrates with different surface appearances, the thickness of the thin film can be accurately controlled, on the other hand, the nucleation overpotential of magnesium is effectively reduced, uniform deposition is promoted, and therefore the service life of a battery is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of magnesium metal surface treatment, and in particular to a method for atomic layer deposition of Al2O3 film for magnesium metal negative electrode. Background Art

[0002] Magnesium metal is considered to be an ideal negative electrode material for the next generation of high energy density batteries due to its low reduction potential, high volumetric capacity and abundant reserves on earth. However, after pure magnesium is assembled into a battery, the reactive species in the electrolyte are easily reduced at the electrode-electrolyte interface, thereby forming a thick and dense passivation layer that prevents the electrochemical reaction from proceeding and Mg 2+ The migration of magnesium ions greatly increases the overpotential of the battery. In addition, the uneven electric field leads to uneven distribution of magnesium ion flow, causing uneven deposition of magnesium, thereby generating magnesium dendrites, which pierce the diaphragm and cause the battery to short-circuit, creating safety hazards.

[0003] Constructing an artificial SEI layer is an effective way to overcome the above problems. An ideal SEI layer can effectively conduct Mg 2+ Instead of conducting electrons, it avoids the decomposition of the surface electrolyte and promotes the reversible deposition / stripping process of magnesium. Studies have confirmed that Al2O3 is effective as a protective layer in Li and Na metal anode systems. However, the intrinsic density of Al2O3 will hinder the transmission of metal ions. Therefore, an extremely thin Al2O3 film layer is needed to reduce the corrosion of the metal surface and minimize the damage to Mg. 2+ Migration is hindered. Currently, Al2O3 thin films are mainly prepared by electron beam evaporation, anodic oxidation, metal organic chemical vapor deposition (MOCVD), radio frequency sputtering and sol-gel method. However, the thin films grown by these methods have poor uniformity, difficult to control thickness, and require a flat sample surface.

[0004] Therefore, in order to meet the demand for high-quality Al2O3 films, a method for producing Al2O3 films with a wide range of applications and high uniformity is urgently needed. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode, which has the characteristics of low cost, simple operation, controllable conditions and good uniformity. On the one hand, it can adapt to substrates with different surface morphologies and can accurately control the film thickness. On the other hand, it effectively reduces the nucleation overpotential of magnesium and promotes uniform deposition, thereby extending the battery life.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode comprises the following steps:

[0008] S1, preparing a substrate sample, placing the substrate sample into a reaction chamber of an atomic layer deposition device, evacuating the chamber and then heating the chamber;

[0009] S2, delivering an aluminum precursor source into the heated reaction chamber through a carrier gas, wherein the aluminum precursor source undergoes self-limiting chemical adsorption with the surface of the substrate sample;

[0010] S3, after the aluminum precursor source is introduced, a carrier gas is introduced into the reaction chamber for purging to clean the reaction byproducts and the residual aluminum precursor source;

[0011] S4, then introducing an oxygen source into the reaction chamber for reaction, and after the reaction is completed, introducing a carrier gas again for purging to complete a single cycle growth;

[0012] S5. Repeat S2 to S4 to deposit Al2O3 films of different thicknesses on the surface of the substrate sample.

[0013] Preferably, in S1, after the substrate sample is placed in the reaction chamber, the reaction chamber is evacuated to 2 hPa and the heating temperature is 200-400°C.

[0014] Preferably, in S1, the substrate sample is one of a magnesium foil, a copper foil having a planar surface, and a carbon cloth having a non-planar surface.

[0015] Preferably, in S1, when a magnesium foil with a planar surface is selected as the substrate sample, the preparation process of the substrate sample is: the magnesium foil is polished using sandpaper of different mesh sizes in a glove box until the surface oxide layer is completely removed.

[0016] Preferably, when copper foil is selected as the substrate sample, the preparation process of the substrate sample is: using methanol and deionized water to clean the surface of the copper foil, remove pollutants on the surface of the copper foil, and dry it.

[0017] Preferably, when a carbon cloth with a non-planar surface is selected as a substrate sample, the preparation process of the substrate sample is as follows: the carbon cloth is placed in concentrated nitric acid for hydrothermal treatment at a hydrothermal temperature of 150°C and a treatment time of 1.5 hours, and then the surface of the carbon cloth after hydrothermal treatment is rinsed with deionized water and alcohol, and dried.

[0018] Preferably, in S2, before the aluminum precursor source is fed into the heated reaction chamber via a carrier gas, the aluminum precursor source is heated at a temperature of 50-200°C.

[0019] Preferably, the aluminum precursor source is trimethylaluminum (TMA), and the oxygen source is water.

[0020] Preferably, the aluminum precursor source and the oxygen source are charged into the reaction chamber in a pulsed form in the presence of a carrier gas, and the carrier gas is high-purity nitrogen.

[0021] The present invention also provides an Al2O3 film deposited by the above-mentioned atomic layer deposition Al2O3 film method for magnesium metal negative electrode, which is prepared by the following reaction formula: Al(CH3)3(g)+H2O(g)→Al2O3(s)+CH4(g).

[0022] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0023] (1) The present invention deposits an Al2O3 film on a magnesium metal negative electrode through atomic layer deposition (ALD) technology, which can achieve precise control of the film thickness. By repeating steps S2 to S4, the Al2O3 film can be grown layer by layer, one layer per cycle, so as to accurately control the total thickness of the film to meet the needs of different application scenarios. In addition, the self-limiting chemical adsorption reaction of the ALD technology ensures the uniform deposition of the film on the surface of the substrate sample, avoiding the uneven thickness or incomplete coverage in the traditional method. At the same time, the present invention can also adapt to substrates with different surface morphologies, regardless of whether the surface morphology of the substrate sample is planar or non-planar, such as holes or grooves, uniform coverage can be achieved.

[0024] (2) The present invention can effectively reduce the nucleation overpotential of magnesium by depositing a 5-20nm thick Al2O3 film on the magnesium metal negative electrode. The nucleation overpotential is the additional potential difference required for metal ions to nucleate on the electrode surface. Reducing the nucleation overpotential can promote the uniform deposition of metal ions and avoid problems such as dendrite growth. In addition, the Al2O3 film, as a protective layer, can also reduce the direct contact between the magnesium metal negative electrode and the electrolyte, thereby reducing the corrosion rate and extending the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 A flowchart of a method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode of the present invention;

[0027] Figure 2 This is the XPS high-resolution spectrum of the 5 nm thick Al2O3 film deposited in Example 1 of the present invention;

[0028] Figure 3The 5 nm thick Al2O3 film deposited in Example 1 of the present invention is subjected to a current density of 0.5 mA cm -2 Electrodeposition curve diagram when

[0029] Figure 4 This is the XPS high-resolution spectrum of the 12.5 nm thick Al2O3 film deposited in Example 2 of the present invention;

[0030] Figure 5 The 12.5 nm thick Al2O3 film deposited in Example 2 of the present invention was subjected to a current density of 0.5 mA cm -2 Electrodeposition curve diagram when

[0031] Figure 6 This is the XPS high-resolution spectrum of the 20 nm thick Al2O3 film deposited in Example 3 of the present invention;

[0032] Figure 7 The 20 nm thick Al2O3 film deposited in Example 3 of the present invention was subjected to a current density of 0.5 mA cm -2 Electrodeposition curve diagram when

[0033] Figure 8 This is the XPS high-resolution spectrum of the 12.5 nm thick Al2O3 film deposited in Example 4 of the present invention;

[0034] Fig. 9 The 12.5 nm thick Al2O3 film deposited in Example 4 of the present invention was subjected to a current density of 0.5 mA cm -2 Electrodeposition curve diagram when

[0035] Fig.10 This is the XPS high-resolution spectrum of the 20 nm thick Al2O3 film deposited in Example 5 of the present invention;

[0036] Fig.11 The 20 nm thick Al2O3 film deposited in Example 5 of the present invention was subjected to a current density of 0.5 mA cm -2 Electrodeposition curve diagram when

[0037] Fig.12 It is an electrodeposition curve diagram of the material substrate deposited in Comparative Example 1 of the present invention;

[0038] Fig.13 This is an electrodeposition curve diagram of the material substrate deposited in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the present invention is described in detail below with reference to the accompanying drawings.

[0041] like Figure 1 As shown, the present invention provides a method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode, comprising the following steps:

[0042] S1, preparing a substrate sample, placing the substrate sample into a reaction chamber of an atomic layer deposition device, evacuating the chamber and then heating the chamber;

[0043] S2, delivering an aluminum precursor source into the heated reaction chamber through a carrier gas, wherein the aluminum precursor source undergoes self-limiting chemical adsorption with the surface of the substrate sample;

[0044] S3, after the aluminum precursor source is introduced, a carrier gas is introduced into the reaction chamber for purging to clean the reaction byproducts and the residual aluminum precursor source;

[0045] S4, then introducing an oxygen source into the reaction chamber for reaction, and after the reaction is completed, introducing a carrier gas again for purging to complete a single cycle growth;

[0046] S5. Repeat S2 to S4 to deposit Al2O3 films of different thicknesses on the surface of the substrate sample.

[0047] Specifically, in S1, after placing the substrate sample in the reaction chamber, the reaction chamber is evacuated to 2hPa, and the heating temperature is 200-400°C. The substrate sample is one of magnesium foil, copper foil and carbon cloth with a planar surface. When magnesium foil with a planar surface is selected as the substrate sample, the preparation process of the substrate sample is: the magnesium foil is polished with sandpaper of different meshes in a glove box until the surface oxide layer is completely removed. When copper foil is selected as the substrate sample, the preparation process of the substrate sample is: the surface of the copper foil is cleaned with methanol and deionized water to remove pollutants on the surface of the copper foil, and then dried. When carbon cloth with a non-planar surface is selected as the substrate sample, the preparation process of the substrate sample is: the carbon cloth is placed in concentrated nitric acid for hydrothermal treatment, the hydrothermal temperature is 150°C, the treatment time is 1.5h, and then the surface of the carbon cloth after hydrothermal treatment is rinsed with deionized water and alcohol, and dried.

[0048] In addition, in S2, before the aluminum precursor source is sent into the heated reaction chamber by the carrier gas, the aluminum precursor source is heated at a temperature of 50 to 200° C. In the above content, the aluminum precursor source is trimethylaluminum TMA, and the oxygen source is water. The aluminum precursor source and the oxygen source are charged into the reaction chamber in a pulsed form in the presence of a carrier gas, and the carrier gas is high-purity nitrogen.

[0049] The Al2O3 film deposited by the above-mentioned atomic layer deposition Al2O3 film method for magnesium metal negative electrode is prepared by the following reaction formula: Al(CH3)3(g)+H2O(g)→Al2O3(s)+CH4(g).

[0050] The present invention will be further described below through specific implementation modes.

[0051] Embodiment 1

[0052] In this embodiment, magnesium foil is selected as the substrate, and the method of growing Al2O3 film using ALD technology includes the following process: using sandpaper of different meshes to polish the magnesium foil substrate in a glove box until the surface oxide layer is completely removed, then wiping its surface clean with dust-free paper, and then sending the treated magnesium foil into the reaction chamber of the ALD equipment within 1 minute, closing the hatch, and then evacuating to 2hPa. Set the heating temperature of the Al precursor source to 50°C, the heating temperature of the oxygen source to 23°C, and the heating temperature in the reaction chamber to 200°C. During the heating process, high-purity nitrogen is continuously introduced for purging. After the Al precursor source and the reaction chamber are heated to the set temperature, the Al precursor source is introduced into the reaction chamber through the carrier gas, and the pulse time is 4s. High-purity nitrogen is introduced again for surface purging for 10s. Subsequently, an oxygen source was introduced into the reaction chamber through a carrier gas with a pulse time of 4 seconds, and high-purity nitrogen was introduced again to purge the surface for 10 seconds to complete a single cycle of growth; the above process was repeated 50 times to deposit an Al2O3 film with a thickness of 5 nm on the magnesium foil.

[0053] The Al2O3 film deposited in this embodiment was characterized by X-ray photoelectron spectroscopy (XPS). Figure 2 As shown in Figure 2, the Al peak at 74.9 eV and the O peak at 531.8 eV prove that the Al2O3 film was successfully deposited. The deposited material substrate was heated to 0.5 mA cm -2 The electrodeposition curve is as follows Figure 3 As shown, an overpotential of 101.3 mV is obtained, which is lower than the overpotential (161.2 mV) deposited on pure magnesium, indicating that the 5 nm Al2O3 film helps promote the uniform deposition of magnesium.

[0054] Embodiment 2

[0055] In this embodiment, magnesium foil is selected as the substrate, and the method of growing Al2O3 film using ALD technology includes the following process: using sandpaper of different meshes to polish the magnesium foil substrate in a glove box until the surface oxide layer is completely removed, then wiping its surface clean with dust-free paper, and then sending the treated magnesium foil into the reaction chamber of the ALD equipment within 1 minute, closing the hatch, and then evacuating to 2hPa. Set the heating temperature of the Al precursor source to 100°C, the heating temperature of the oxygen source to 23°C, and the heating temperature in the reaction chamber to 300°C. During the heating process, high-purity nitrogen is continuously introduced for purging. After the Al precursor source and the reaction chamber are heated to the set temperature, the Al precursor source is introduced into the reaction chamber through the carrier gas, and the pulse time is 4s. High-purity nitrogen is introduced again for surface purging for 10s. Subsequently, an oxygen source was introduced into the reaction chamber through a carrier gas with a pulse time of 4 seconds, and high-purity nitrogen was introduced again to purge the surface for 10 seconds to complete a single cycle of growth; the above process was repeated 125 times to deposit an Al2O3 film with a thickness of 12.5 nm on the magnesium foil.

[0056] The Al2O3 film deposited in this embodiment was characterized by X-ray photoelectron spectroscopy (XPS). Figure 4 As shown in Figure 2, it is proved that the Al2O3 film was successfully deposited. The deposited material substrate was heated to 0.5 mA cm -2 The electrodeposition curve is as follows Figure 5 As shown, an overpotential of 94.0 mV is obtained, which is 77.2 mV lower than the overpotential deposited on pure magnesium, indicating that the 12.5 nm Al2O3 film helps promote the uniform deposition of magnesium.

[0057] Embodiment 3

[0058] In this embodiment, magnesium foil is selected as the substrate, and the method of growing Al2O3 film using ALD technology includes the following process: using sandpaper of different meshes to polish the magnesium foil substrate in a glove box until the surface oxide layer is completely removed, then wiping its surface clean with dust-free paper, and then sending the treated magnesium foil into the reaction chamber of the ALD equipment within 1 minute, closing the hatch, and then evacuating to 2hPa. Set the heating temperature of the Al precursor source to 200°C, the heating temperature of the oxygen source to 23°C, and the heating temperature in the reaction chamber to 400°C. During the heating process, high-purity nitrogen is continuously introduced for purging. After the Al precursor source and the reaction chamber are heated to the set temperature, the Al precursor source is introduced into the reaction chamber through the carrier gas, and the pulse time is 4s. High-purity nitrogen is introduced again for surface purging for 10s. Subsequently, an oxygen source was introduced into the reaction chamber through a carrier gas with a pulse time of 4 seconds, and high-purity nitrogen was introduced again to purge the surface for 10 seconds to complete a single cycle of growth; the above process was repeated 200 times to deposit an Al2O3 film with a thickness of 20 nm on the magnesium foil.

[0059] The Al2O3 film deposited in this embodiment was characterized by X-ray photoelectron spectroscopy (XPS). Figure 6 As shown in Figure 2, it is proved that the Al2O3 film was successfully deposited. The deposited material substrate was heated to 0.5 mA cm -2 The electrodeposition curve is as follows Figure 7 As shown, an overpotential of 107.3 mV is obtained, which is 53.9 mV lower than the overpotential deposited on pure magnesium, indicating that the 20 nm Al2O3 film helps promote the uniform deposition of magnesium.

[0060] Embodiment 4

[0061] In this embodiment, copper foil is selected as the substrate, and the method of growing Al2O3 film using ALD technology includes the following process: using methanol and deionized water to clean the surface of the copper foil, remove the pollutants on its surface, and dry it; then the treated copper foil is sent into the reaction chamber of the ALD equipment within 1 minute, the hatch is closed, and then evacuated to 2hPa. The heating temperature of the Al precursor source is set to 200°C, the heating temperature of the oxygen source is set to 23°C, and the heating temperature in the reaction chamber is set to 300°C. During the heating process, high-purity nitrogen is continuously introduced for purging. After the Al precursor source and the reaction chamber are heated to the set temperature, the Al precursor source is introduced into the reaction chamber through the carrier gas, and the pulse time is 4s. High-purity nitrogen is introduced again for surface purging for 10s. Subsequently, an oxygen source was introduced into the reaction chamber through a carrier gas with a pulse time of 4 seconds, and high-purity nitrogen was introduced again to purge the surface for 10 seconds to complete a single cycle of growth; the above process was repeated 125 times to deposit an Al2O3 film with a thickness of 12.5 nm on the copper foil.

[0062] The Al2O3 film deposited in this embodiment was characterized by X-ray photoelectron spectroscopy (XPS). Figure 8 As shown in Figure 2, it is proved that the Al2O3 film was successfully deposited. The deposited material substrate was heated to 0.5 mA cm -2 The electrodeposition curve is as follows Fig. 9 As shown, an overpotential of 171.2 mV is obtained, which is much lower than the overpotential (247.1 mV) deposited on pure copper, further indicating that the 12.5 nm Al2O3 film can effectively promote the uniform deposition of magnesium on the copper substrate.

[0063] Embodiment 5

[0064] In this embodiment, carbon cloth is selected as a substrate, and the method of growing Al2O3 film using ALD technology includes the following process: placing the carbon cloth in concentrated nitric acid for hydrothermal treatment, the hydrothermal temperature is 150°C, and the hydrothermal time is 1.5h, then the acid-treated carbon cloth is rinsed with deionized water and dried. Then the activated carbon cloth is sent into the reaction chamber of the ALD equipment, the hatch is closed, and then the vacuum is evacuated to 2hPa. The heating temperature of the Al precursor source is set to 200°C, the heating temperature of the oxygen source is set to 23°C, and the heating temperature in the reaction chamber is set to 300°C. During the heating process, high-purity nitrogen is continuously introduced for purging. After the Al precursor source and the reaction chamber are heated to the set temperature, the Al precursor source is introduced into the reaction chamber through the carrier gas, the pulse time is 4s, and high-purity nitrogen is introduced again for surface purging for 10s. Subsequently, an oxygen source was introduced into the reaction chamber through a carrier gas with a pulse time of 4 seconds, and high-purity nitrogen was introduced again to purge the surface for 10 seconds to complete a single cycle of growth; the above process was repeated 125 times to deposit an Al2O3 film with a thickness of 12.5 nm on the carbon cloth.

[0065] The Al2O3 film deposited in this embodiment was characterized by X-ray photoelectron spectroscopy (XPS). Fig.10 As shown in Figure 2, it is proved that the Al2O3 film was successfully deposited. The deposited material substrate was heated to 0.5 mA cm -2 The electrodeposition curve is as follows Fig.11 As shown, an overpotential of 127.1 mV was obtained, which was 32.3 mV lower than the overpotential deposited on pure carbon cloth, indicating that the 12.5 nm Al2O3 film can effectively promote the uniform deposition of magnesium on the carbon cloth substrate.

[0066] Comparative Example 1

[0067] The difference from Example 1 is that the Al2O3 film with a thickness of 2 nm is obtained by repeating the cycle twice. -2 When the electrodeposition curve of the material substrate deposited in Comparative Example 1 is as follows Fig.12 As shown, it can be found that the improvement of Mg deposition by 2 nm Al2O3 film is almost negligible.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that the Al2O3 film with a thickness of 25 nm is obtained by repeating the cycle 250 times. -2 When the electrodeposition curve of the material substrate deposited in Comparative Example 2 is as follows Fig.13 As shown, it can be found that when magnesium is deposited on an Al2O3 film with a thickness of 25 nm, the overpotential increases, which is not conducive to the deposition of magnesium. This is because the overly thick Al2O3 has good density and seriously hinders the transmission of magnesium ions.

[0070] According to the above-mentioned embodiments and comparative examples, the overpotential data obtained are shown in Table 1.

[0071] Table 1 Overpotential data table

[0072] Implementation Overpotential(mV) Embodiment 1 101.3 Embodiment 2 94.0 Embodiment 3 107.3 Embodiment 4 127.1 Embodiment 5 171.2 Comparative Example 1 161.2 Comparative Example 2 198.0

[0073] According to the comparison between Table 1 and various embodiments, the present invention adopts the above-mentioned atomic layer deposition Al2O3 film method for magnesium metal negative electrode, which has the characteristics of low cost, simple operation, controllable conditions and good uniformity. On the one hand, it can adapt to substrates with different surface morphologies and can accurately control the film thickness. On the other hand, it effectively reduces the nucleation overpotential of magnesium and promotes uniform deposition, thereby extending the battery life.

[0074] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0075] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode, characterized in that: The following steps are involved: S1, preparing a substrate sample, and placing the substrate sample into a reaction chamber of an atomic layer deposition device, evacuating the chamber and then heating the chamber; S2, delivering an aluminum precursor source into the heated reaction chamber through a carrier gas, wherein the aluminum precursor source undergoes self-limiting chemical adsorption with the surface of the substrate sample; S3, after the aluminum precursor source is introduced, a carrier gas is introduced into the reaction chamber for purging to clean the reaction byproducts and the residual aluminum precursor source; S4, then introducing an oxygen source into the reaction chamber for reaction, and after the reaction is completed, introducing a carrier gas again for purging to complete a single cycle growth; S5. Repeat S2 to S4 to deposit Al2O3 films of different thicknesses on the surface of the substrate sample.

2. The method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode according to claim 1, characterized in that: In S1, after the substrate sample is placed in the reaction chamber, the reaction chamber is evacuated to 2 hPa and the heating temperature is 200-400°C.

3. The method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode according to claim 2, characterized in that: In S1, the substrate sample is one of a magnesium foil having a planar surface, a copper foil, and a carbon cloth having a non-planar surface.

4. The method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode according to claim 3, characterized in that: In S1, when a magnesium foil with a planar surface is selected as a base sample, the preparation process of the base sample is: the magnesium foil is polished using sandpaper of different meshes in a glove box until the surface oxide layer is completely removed.

5. The method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode according to claim 3, characterized in that: When copper foil is selected as the substrate sample, the preparation process of the substrate sample is as follows: the surface of the copper foil is cleaned with methanol and deionized water to remove pollutants on the surface of the copper foil, and then dried.

6. The method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode according to claim 3, characterized in that: When a carbon cloth with a non-planar surface is selected as a substrate sample, the preparation process of the substrate sample is as follows: the carbon cloth is hydrothermally treated in concentrated nitric acid at a hydrothermal temperature of 150° C. for 1.5 h, and then the surface of the carbon cloth after hydrothermal treatment is rinsed with deionized water and alcohol, and dried.

7. The method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode according to claim 1, characterized in that: In S2, before the aluminum precursor source is delivered into the heated reaction chamber by a carrier gas, the aluminum precursor source is heated at a temperature of 50-200°C.

8. The method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode according to claim 1, characterized in that: The aluminum precursor source is trimethylaluminum (TMA), and the oxygen source is water.

9. The method for atomic layer deposition of Al2O3 thin film for magnesium metal negative electrode according to claim 8, characterized in that: The aluminum precursor source and the oxygen source are charged into the reaction chamber in a pulsed form in the presence of a carrier gas, and the carrier gas is high-purity nitrogen.

10. The Al2O3 film deposited by the atomic layer deposition Al2O3 film method for magnesium metal negative electrode according to any one of claims 1 to 9, characterized in that: It is prepared by the following reaction formula: Al(CH3)3(g)+H2O(g)→Al2O3(s)+CH4(g).

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