A negative electrode material Mg-Sn alloy for magnesium-air battery and its preparation method

Abstract

The present invention discloses a Mg-Sn alloy as a negative electrode material for a magnesium-air battery and a preparation method thereof, belonging to the technical field of electrode materials for magnesium-air batteries. The alloy comprises the following components in mass percentage: Mg: 99.7-99.9 wt.%, Sn: 0.1-0.3 wt.%. Under a mixed protective atmosphere of CO2 and N2 at 750 °C, a as-cast blank is obtained by melting in a crucible resistance furnace. After mechanical processing of the as-cast blank, homogenization treatment is carried out, followed by rolling deformation treatment, and finally annealing to obtain the blank. This alloy has no precipitation phase and has a uniform micron-sized equiaxed grain structure, and the average recrystallized grain size is: 7.59 ± 0.26 μm. The Mg-Sn alloy negative electrode material of the present invention has good discharge performance and high dissolution kinetics.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnesium-air battery electrode materials, and particularly relates to a magnesium-air battery negative electrode material Mg-Sn alloy and a preparation method thereof. Background Art

[0002] In recent years, with the increase in the consumption of fossil energy and the huge damage to the environment, reducing the use of non-renewable energy and developing green, advanced, and clean energy storage systems have become new challenges in current scientific research. Metal-air batteries have the advantages of high theoretical energy density, rich resources, environmental protection, and no pollution, and have become a promising green energy battery. Metal-air batteries mainly include: lithium-air batteries, zinc-air batteries, magnesium-air batteries, etc. In contrast, magnesium-air batteries have the characteristics of high theoretical discharge voltage, high Faraday capacity, negative standard electrode potential, and low density, and are the best choice for the negative electrode material of metal-air batteries. However, on the one hand, the low anodic reaction kinetics and the accumulation of discharge products on the anode surface reduce the reactive area on the electrode surface, resulting in voltage decay. On the other hand, due to the severe hydrogen evolution caused by the negative difference effect (NDE) and the "chunk effect" (CE) caused by the detachment of the undissolved Mg matrix from the anode surface, the battery performance decreases. These disadvantages severely limit their wide application. Therefore, developing a magnesium anode material with high anodic dissolution ability, large anodic active area, low hydrogen evolution rate, and low chunk effect is the key to improving the discharge performance of magnesium-air batteries.

[0003] Research shows that the alloying and plastic deformation composite process is an effective strategy to improve these limitations of magnesium anodes. However, high alloying will lead to higher alloy costs and severe local corrosion. Summary of the Invention

[0004] Aiming at the deficiencies of the magnesium-air battery in the above-mentioned prior art, the present invention provides a magnesium-air battery negative electrode material Mg-Sn alloy and a preparation method thereof. Using magnesium and tin as raw materials, through melting and casting into ingots, solution treatment, cold rolling, and annealing, a Mg-Sn microalloyed magnesium alloy negative electrode material with excellent discharge performance is prepared.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A magnesium-air battery negative electrode material Mg-Sn alloy, comprising the following components in mass percentage: Mg: 99.7-99.9 wt.%, Sn: 0.1-0.3 wt.%, and the Mg-Sn alloy has a precipitation-free and uniform micron-sized equiaxed grain structure.

[0007] Furthermore, the purity of the Mg is greater than 99.9%, and the purity of the Sn is greater than 99.9%.

[0008] The present invention also provides a method for preparing a Mg-Sn alloy as the negative electrode material of a magnesium-air battery, comprising the following steps:

[0009] Step 1: Melting

[0010] Under the protection of a CO2+N2 protective gas, magnesium blocks and tin particles are sequentially melted to obtain an alloy liquid. A refining agent is added to the alloy liquid to remove the oxide film on the melt surface, and then casting is carried out. After air cooling and solidification, an ingot is obtained;

[0011] The specific melting steps are as follows:

[0012] 1) Heat the magnesium blocks from 400°C to 710°C, and keep them at this temperature for 25 minutes to obtain molten magnesium. At this time, the magnesium blocks are completely melted, and the oxide film on the surface of the alloy liquid is removed using a slag skimmer;

[0013] 2) Add Sn particles to the molten magnesium, heat it to 750°C and keep it at this temperature for 20 minutes, so that the added alloying elements have enough time to fully diffuse in the molten magnesium alloy liquid after melting, making the alloy composition uniform, thereby obtaining the alloy liquid;

[0014] 3) Cool the alloy liquid to 740°C, slowly add the refining agent and stir vigorously. The whole process lasts for 1 - 2 minutes until the surface of the alloy liquid presents a mirror surface. After the refining is completed, keep it at 740°C for 20 minutes; then lower the temperature to 710°C, remove the oxide film on the melt surface, carry out casting, and obtain an ingot after air cooling and solidification.

[0015] Step 2: Homogenization treatment

[0016] Under the protection of pure argon gas, the ingot is subjected to a two-stage solution treatment;

[0017] Step 3: Rolling deformation treatment

[0018] The ingot after the two-stage solution treatment is machined to obtain a rolled blank with a length of 120 mm, a width of 100 mm, and a thickness of 10 mm. Then, the blank is subjected to rolling treatment and annealing to obtain a rolled bar, that is, the Mg-Sn alloy as the negative electrode material of the magnesium-air battery.

[0019] Furthermore, in Step 1, the volume ratio of CO2 to N2 in the CO2+N2 protective gas is 1∶16. The purpose is to avoid oxidation of the alloy, and if the volume ratio exceeds this value, the quality of the melt will decrease.

[0020] During the smelting process, magnesium blocks, tin particles, refining agents, and casting molds need to be pre-placed in a 200°C drying oven and dried for 30 minutes before use. The crucible used for smelting is placed in a 300°C resistance furnace and kept warm for 20 minutes, and then a coating is applied to the inner surface of the crucible, and the coating is repeated 3 times to ensure that the inner surface of the crucible is completely covered by the coating and the inner surface is smooth. The coating used is a mixture of zinc oxide, water glass, and water in a ratio of 1:1:5.3 by weight.

[0021] When adding Sn particles to the molten magnesium, a small piece of magnesium block can be placed after the rapid addition of Sn particles. The purpose is to press the Sn particles under the molten magnesium liquid surface, which is beneficial for full dissolution and preventing burning loss. In principle, there is no limit to the size of the small piece of magnesium block placed later, as long as it can press the Sn particles under the liquid surface. The total amount of magnesium added in the two times before and after is the total amount of magnesium added in the present invention.

[0022] The entire smelting process is carried out under a CO2+N2 protective gas, and the gas volume ratio remains unchanged, including the casting blank stage. The alloy liquid is poured into a copper mold preheated to 200°C under the protection of a CO2+N2 atmosphere to obtain a sheet-shaped sample blank.

[0023] Further, in step 2, in order to allow the added alloying elements to fully dissolve into the matrix and homogenize the alloy structure, a two-stage solution treatment is adopted. The two-stage solution treatment is: solution treatment at 320°C for 1 hour, solution treatment at 500°C for 3 hours, and then water quenching.

[0024] Further, in step 3, the rolling treatment refers to: hot rolling at 300°C, with a roll diameter of 350 mm, a rolling speed of 130 mm / s, and rolling for 5 passes. The sample thickness is reduced from 10 mm to 4 mm.

[0025] Further, in step 3, the annealing is carried out at 300°C for 10 minutes.

[0026] Alloying is one of the effective methods to improve the performance of the negative electrode of magnesium-air batteries. Theoretically, Sn can provide a relatively high volume energy density (7.413 W·h·g -1 ) for the diffusion of single Mg atoms (0.497 eV), hydrogen overpotential, and a lower migration barrier. Therefore, Sn is the preferred alloying element to improve the dissolution kinetics of Mg anodes. In addition, the alloying element Sn enhances the migration of Mg 2+ ions through the dissolution and redeposition behavior during the discharge process, maintains the reactive area on the electrode surface, thereby inhibiting the voltage decay phenomenon, and on the other hand effectively inhibits the formation of a dense passivation film, and reduces the self-corrosion hydrogen evolution rate due to its high hydrogen evolution overpotential.

[0027] The present invention also provides an application of the above-mentioned magnesium-air battery negative electrode material Mg-Sn alloy in the negative electrode of a magnesium-air battery.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] (1) Compared with the background technology, the present invention is significantly more advanced. It aims to solve the problem of low discharge performance of negative electrode materials for magnesium-air batteries. High-purity magnesium and tin are used as raw materials. After smelting, solid solution treatment, low-temperature rolling and finally annealing, a Mg-Sn microalloyed alloy, which is a negative electrode material for magnesium-air batteries, is prepared. The preparation method has advanced technology and accurate and detailed data.

[0030] (2) The present invention adds non-toxic and environmentally friendly alloying element Sn to the magnesium alloy, and the addition amount thereof does not exceed 1.0%, which is beneficial to reducing the cost of the negative electrode material.

[0031] (3) The Mg-Sn microalloyed alloy of the present invention is directly rolled after casting, which shortens the preparation process and can achieve grain refinement after rolling.

[0032] (4) Grain refinement improves the comprehensive performance of the alloy. The discharge voltage is 1.36V and the anode utilization rate is 58.2%.

[0033] (5) The Mg-Sn microalloyed alloy prepared by the present invention obtains a uniform equiaxed fine grain structure after rolling deformation treatment, which significantly improves the negative electrode dissolution kinetics, effectively inhibits hydrogen self-corrosion and block effect, and leads to an improvement in discharge performance. -2 At this current density, the discharge voltage reaches 1.36V and the specific energy reaches 1730.96mW·h·g -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0035] Figure 1 The metallographic microstructure diagram of the alloy prepared in Example 1 of the present invention;

[0036] Figure 2 is the average grain size of the alloy prepared in Example 1 of the present invention;

[0037] Figure 3 The SEM microstructure and XRD diagram of the alloy prepared in Example 1 of the present invention;

[0038] Figure 4 This is a polarization curve diagram of the alloy prepared in Example 1 of the present invention in 3.5wt.% NaCl electrolyte. DETAILED DESCRIPTION

[0039] A detailed description of various exemplary embodiments of the present invention will now be given. This detailed description should not be construed as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0042] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the description of the present invention, which are obvious to those skilled in the art. Other embodiments obtained from the description of the present invention are obvious to those skilled in the art. The description and examples of this application are merely exemplary.

[0043] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0044] All raw materials used in the following examples of the present invention are obtained commercially.

[0045] In view of the deficiencies of the above-mentioned existing magnesium-air batteries in the prior art, the present invention proposes a negative electrode material Mg-Sn alloy for magnesium-air batteries and a preparation method thereof. Using magnesium and tin as raw materials, through melting and casting into ingots, solution treatment, cold rolling, and annealing, a Mg-Sn microalloyed magnesium alloy negative electrode material with excellent discharge performance is prepared. The Mg-Sn alloy can improve the dissolution kinetics of the anode of the magnesium-air battery, inhibit the "block effect" and hydrogen evolution self-corrosion. The alloy includes the following mass percentages: Mg: 99.7 - 99.9 wt.%, Sn: 0.1 - 0.3 wt.%, preferably Mg: 99.9 wt.%, Sn: 0.1 wt.% and Mg: 99.7 wt.%, Sn: 0.3 wt.%, more preferably Mg: 99.9 wt.%, Sn: 0.1 wt.%. Pure magnesium can also be directly selected as the negative electrode material of the magnesium-air battery. Under a mixed protective atmosphere of CO2 and N2 at 750 °C, a as-cast blank is obtained by melting in a crucible resistance furnace, homogenized after machining the as-cast blank, then subjected to rolling deformation treatment, and finally annealed to obtain a blank. The rolled magnesium alloy has no precipitation phase and has a uniform micron-sized equiaxed grain structure, and the average recrystallized grain size is: 7.59 ± 0.26 μm. The Mg-Sn microalloyed alloy negative electrode material of the present invention has good discharge performance and high dissolution kinetics. The specific technical solutions are as follows:

[0046] A Mg-Sn alloy as the negative electrode material of a magnesium-air battery, comprising components in the following mass percentages: Mg: 99.9 wt.%, Sn: 0.1 wt.%. This Mg-Sn alloy has a precipitation-free and uniform micron-sized equiaxed grain structure. The purpose of controlling the Sn addition amount to 0.1 wt.% is to improve the anode reaction kinetics. Beyond this range, the Mg2Sn second phase is generated, weakening the anode discharge performance, and below this range, the anode discharge performance is reduced.

[0047] Furthermore, the purity of the Mg is greater than 99.9%, and the purity of the Sn is greater than 99.9%.

[0048] The present invention also provides a preparation method for a Mg-Sn alloy as the negative electrode material of a magnesium-air battery, comprising the following steps:

[0049] Step 1: Alloy melting

[0050] Melting step

[0051] (1) Weigh the raw materials according to the formula, and place pure magnesium blocks, pure tin particles, a refining agent, and a casting mold with purities all greater than 99.9% in a drying oven at 200 °C for 30 min.

[0052] (2) Place the crucible in a resistance furnace at about 300 °C and keep it warm for 20 min. After taking it out, evenly coat the inner surface of the crucible with the coating. Repeat the above steps 3 times to ensure that the inner surface of the crucible is completely covered with the coating and the inner surface is smooth.

[0053] (3) When the temperature of the resistance furnace reaches 400 °C, put in a relatively large dried pure magnesium block. After closing the furnace lid tightly, introduce the protective gas of CO2 + N2 to isolate the air.

[0054] (4) Adjust the temperature of the resistance furnace to 710 °C. After the furnace temperature rises to the preset temperature, keep it warm for 25 min. At this time, the pure magnesium block is completely melted. Next, use a slag skimmer to remove the oxide film on the surface of the magnesium alloy liquid. Then, quickly add pure metal Sn particles into the alloy liquid, and then put in a small pure magnesium block. The purpose is to press the Sn particles under the molten magnesium alloy liquid surface, which is beneficial to full dissolution and prevent burning loss.

[0055] (5) Adjust the temperature of the resistance furnace to 750 °C again. After the furnace temperature rises to the preset temperature again, keep it warm for 20 min so that the added Sn alloy element has enough time to fully diffuse in the molten magnesium alloy liquid after melting, making the alloy composition uniform.

[0056] (6) After the heat preservation ends, adjust the furnace temperature to 740 °C. Prepare to refine the molten metal. Slowly add the refining agent taken out from the oven and stir vigorously. The whole process lasts for 1 - 2 min until the alloy liquid surface presents a mirror surface. After the refining ends, raise the furnace temperature to 740 °C again and keep it warm for 20 min.

[0057] The refining agent is composed of MgCl2, KCl, BaCl2 and CaF2 mixed together, and the mass ratio is 46∶40∶8∶5.

[0058] (7) After the heat preservation ends, lower the furnace temperature to 710 °C, remove the oxide film on the melt surface. Then, pour the alloy melt into a copper mold preheated to 200 °C under the protection of the CO2 + N2 atmosphere to obtain a plate-shaped sample blank. After the ingot is air-cooled and solidified, take out the ingot. In theory, there is no limitation on the casting mold. In the embodiment of the present invention, a copper mold is selected.

[0059] Step 2: Solution treatment

[0060] The ingot is subjected to homogenization treatment in a heat treatment furnace of model OTF - 1200X under the protection atmosphere of pure argon. In order to allow the added alloy elements to fully dissolve into the matrix and homogenize the alloy structure, a two-stage solution treatment is adopted. The parameters of the two-stage solution treatment are: 320 °C × 1 h + 500 °C × 3 h, and then water quenching is carried out.

[0061] Step 3: Rolling deformation treatment

[0062] The solution-treated ingot is machined to obtain an extrusion blank, and a rolling blank with a length of 120 mm, a width of 100 mm, and a thickness of 10 mm is obtained. Then, hot rolling is carried out at 300 °C, the roll diameter is 350 mm, the rolling speed is 130 mm / s, and the rolling is carried out for 5 passes, and the thickness is reduced from 10 mm to 4 mm. Finally, annealing is carried out at 300 °C for 10 min to obtain a rolled bar, that is, the Mg-Sn alloy as the negative electrode material of the magnesium-air battery.

[0063] The following examples are further descriptions of the technical solutions of the present invention.

[0064] Example 1

[0065] A preparation method of an Mg-Sn alloy as the negative electrode material of a magnesium-air battery comprises the following steps:

[0066] Step 1: Raw material preparation

[0067] Prepare the raw materials according to the required raw material ratio in Table 1-3, and place the magnesium blocks and tin particles of specific quality polished with a grinding wheel in an oven at 200 °C for drying for 30 min. The surfaces of the crucible, stirring rod, and slag skimming spoon are evenly brushed dry with the coating prepared with talcum powder. Place the crucible in a resistance furnace at 300 °C for heat preservation for 20 min, take it out, and evenly coat the inner surface of the crucible with the coating. Repeat the above steps 3 times to ensure that the inner surface of the crucible is completely covered with the coating and the inner surface is smooth.

[0068] Table 1 Quality, shape, and purity of chemical raw materials

[0069]

[0070]

[0071] Table 2 Coating formula

[0072] Zinc oxide / g Water / mL Sodium silicate / g 22.5 120 22.5

[0073] Table 3 Component ratio of refining agent

[0074] Main component <![CDATA[MgCl2]]> KCl <![CDATA[BaCl2]]> <![CDATA[CaF2]]> Percentage / % 46 40 8 5

[0075] Step 2: Alloy melting

[0076] (1) Place 530 g of dried magnesium blocks in a crucible preheated at 400 °C in advance, and simultaneously introduce a CO2+SF6 protective gas (the volume ratio of CO2 and N2 is 1:16). Wait for the furnace temperature to rise to 710 °C, keep it warm for 25 min, and use a slag skimming spoon to remove the oxide film on the surface of the magnesium alloy liquid; then add the dried Sn particles into it, and then put 69.4 g of magnesium blocks to press them below the liquid surface.

[0077] (2) When the furnace temperature further rises to 750 °C, hold for 20 min to allow the alloy to fully diffuse in the molten magnesium alloy liquid and homogenize the alloy composition.

[0078] (3) Subsequently, lower the furnace temperature to 740 °C for refining. During refining, slowly add 8 g of refining agent and simultaneously use a stirring rod to vigorously stir the alloy liquid. The whole process lasts for 1 - 2 min.

[0079] (4) After refining, keep the resistance furnace at 740 °C for 20 min. Then, when the furnace temperature drops to 710 °C, pour the alloy melt into a copper mold preheated to 200 °C under the protection of a CO2 + N2 (volume ratio of CO2 to N2 is 1:16) atmosphere to obtain a plate - shaped sample blank. After the ingot air - cools and solidifies, open the mold and take out the ingot.

[0080] Step 2: Solution treatment

[0081] The ingot is homogenized in a protective atmosphere of pure argon in a heat treatment furnace of model OTF - 1200X. The homogenization treatment adopts double - stage solution treatment with parameters: 320 °C × 1 h + 500 °C × 3 h, followed by water quenching (temperature 25 °C, time 1 min).

[0082] Step 3: Rolling deformation treatment

[0083] The ingot after solution treatment is polished with 2000# sandpaper to make its surface bright, and then machined into an extrusion blank. A rolling blank with a length of 120 mm, a width of 100 mm, and a thickness of 10 mm is obtained. Then, hot rolling is carried out at 300 °C, the roll diameter is 350 mm, the rolling speed is 130 mm / s, the rolling reduction rate is 60%, and it is rolled for 5 passes, with the thickness reduced from 10 mm to 4 mm. Finally, anneal at 300 °C for 10 min to obtain a rolled bar, that is, the Mg - Sn alloy for the negative electrode of the magnesium - air battery.

[0084] Figure 1 This is the metallographic microstructure diagram of the alloy prepared in Example 1 of the present invention; it can be seen from the figure that the alloy has a precipitation - free and uniform micron - sized equiaxed grain structure.

[0085] Figure 2 The average grain size (AGS) of the alloy prepared in Example 1 of the present invention is 7.59 μm.

[0086] Figure 3 This is the SEM microstructure diagram and XRD diagram of the alloy prepared in Example 1 of the present invention; it can be seen from the figure that only the α - Mg single phase can be observed.

[0087] Figure 4The polarization curve of the alloy prepared in Example 1 of the present invention in a 3.5 wt.% NaCl electrolyte solution. As can be seen from the figure, the Ecorr value of Mg-Sn is much lower than that of pure Mg, indicating that Sn microalloying can effectively improve the thermodynamic stability of Mg.

[0088] Example 2

[0089] Same as Example 1, except that the mass of Mg is 598.2 g and the mass of Sn is 1.8 g.

[0090] Example 3

[0091] Same as Example 1, except that the anode is replaced with pure magnesium.

[0092] The Mg-Sn alloy prepared in Example 1 was used as the negative electrode material, and its performance was tested at different discharge current densities. The results are shown in Table 4.

[0093] Table 4 Battery performance of each magnesium-air battery

[0094]

[0095]

[0096] As can be seen from Table 4, the energy density of the T0 anode increases with the increase of the current density, and the peak value is 1730.96 mW·h·g -1 .

[0097] Table 5 shows the battery performance of the negative electrode alloy materials prepared in Examples 1-3 at a discharge current density of 10 mA·cm -2 .

[0098] Table 5

[0099]

[0100] As can be seen from Table 5, at 10 mA·cm -2 , the negative electrode alloy materials prepared in Examples 1-3 all have excellent performance. In particular, the Mg-0.1Sn alloy, as the anode material of the magnesium-air battery, exhibits more excellent discharge voltage, anode efficiency and specific energy than pure magnesium and the Mg-0.3Sn alloy.

[0101] The above are only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the technical field of the present application within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A preparation method of a negative electrode material Mg-Sn alloy for a magnesium-air battery, characterized in that, The negative electrode material Mg-Sn alloy of the magnesium-air battery comprises the following components by mass percentage: Mg: 99.9 wt.%, Sn: 0.1 wt.%; the purity of the Mg is greater than 99.9%, and the purity of the Sn is greater than 99.9%; The preparation method of the negative electrode material Mg-Sn alloy of the magnesium-air battery comprises the following steps: Step 1: Melting (1) Place 530 g of dried magnesium blocks in a crucible preheated at 400 °C in advance, and simultaneously introduce a CO2 + N2 protective gas. The volume ratio of CO2 to N2 is 1:

16. Wait until the furnace temperature rises to 710 °C, keep it warm for 25 min, and use a slag skimmer to remove the oxide film on the surface of the magnesium alloy liquid; then add 0.6 g of dried Sn particles to the magnesium alloy liquid, and then put 69.4 g of magnesium blocks to press the Sn particles below the liquid surface; (2) Wait until the furnace temperature further rises to 750 °C and keep it warm for 20 min to enable the alloy to be fully diffused in the molten magnesium alloy liquid and make the alloy composition uniform; (3) Then lower the furnace temperature to 740 °C for refining treatment. When refining, slowly add 8 g of refining agent and simultaneously use a stirring rod to vigorously stir the alloy liquid. The whole process lasts for 1 - 2 min; (4) After the refining is completed, keep the resistance furnace at 740 °C for 20 min, and then wait until the furnace temperature drops to 710 °C. Pour the alloy melt into a copper mold preheated at 200 °C under a CO2 + N2 protective atmosphere to obtain a plate-shaped sample blank. After the ingot is air-cooled and solidified, open the mold and take out the ingot; Step 2: Homogenization treatment The ingot is subjected to homogenization treatment in a heat treatment furnace under a pure argon protective atmosphere. The homogenization treatment adopts a two-stage solution treatment with parameters: 320 °C × 1 h + 500 °C × 3 h, and then water quench at 25 °C for 1 min; Step 3: Rolling deformation treatment The ingot after the two-stage solution treatment is polished with 2000# sandpaper to make its surface bright, and then machined into an extrusion blank to obtain a rolling blank with a length of 120 mm, a width of 100 mm, and a thickness of 10 mm. Then hot roll at 300 °C, the roll diameter is 350 mm, the rolling speed is 130 mm / s, the rolling reduction rate is 60%, and roll for 5 passes. The thickness is reduced from 10 mm to 4 mm. Finally, anneal at 300 °C for 10 min to obtain a rolled bar, that is, the negative electrode material Mg-Sn alloy of the magnesium-air battery; The negative electrode material Mg-Sn alloy of the magnesium-air battery has no precipitation phase and has a uniform micron-sized equiaxed grain structure, and the average recrystallized grain size is 7.59 ± 0.26 μm.

2. Application of the negative electrode material Mg-Sn alloy of the magnesium-air battery prepared by the preparation method as claimed in claim 1 as the negative electrode material of the magnesium-air battery.

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