A heterogeneous structure Mg-Sc-Y anode material, battery, application and preparation method

Abstract

The present invention discloses a heterogeneous structure Mg-Sc-Y anode material, a battery, its applications and preparation method, belonging to the technical field of anode materials for magnesium-air batteries. The anode material comprises the following components by mass percentage: scandium: 0.1%, yttrium: 0.1%, and the balance is magnesium. The present invention adopts a microalloying design, adding a very small amount of rare earth elements to pure magnesium, reducing the cost of the anode material and its tendency to galvanic corrosion. Through a short process design of solution treatment after melting and extrusion, a heterogeneous microstructure is designed, which consists of elongated deformed grains and fine equiaxed grains; the invention enhances the corrosion resistance of the anode of the magnesium-air battery, activates the anode reaction kinetics, increases the effective anode reaction area, reduces the side reaction of self-corrosion hydrogen evolution, and realizes the synergistic improvement of the battery discharge voltage and anode efficiency. This invention is convenient for preparation and application, and is of great significance for extending the discharge life of magnesium-air batteries and large-scale popularization.

Description

Technical Field

[0001] The present invention belongs to the technical field of anodic materials for magnesium-air batteries, and particularly relates to a heterostructure Mg-Sc-Y anodic material, a battery, an application and a preparation method thereof. Background Art

[0002] In order to cope with the crises of climate change and fossil fuel shortage, countries are actively seeking new energy devices and increasing their share in the total energy production. Metal-air batteries have become new energy storage and conversion devices with great application potential due to their high energy density, easy availability of raw materials, and pollution-free production process.

[0003] Magnesium and its alloys are ideal anodic materials for metal-air batteries due to their relatively negative standard electrode potential (-2.37V vs. standard hydrogen electrode) and high theoretical specific energy (6.8 kWh / kg). At the same time, the rich reserves of magnesium resources in China make the large-scale promotion of such batteries low-cost and promising.

[0004] However, the large-scale application of current anodic materials for magnesium-air batteries still faces the following problems: on the one hand, the adhesion effect of discharge products and the sluggish anodic reaction kinetics reduce the surface reaction area and increase the internal resistance of the system, resulting in the actual discharge voltage being much lower than the theoretical value; on the other hand, the negative difference effect (NDE) induces severe anodic hydrogen evolution and self-corrosion, reducing the anodic efficiency.

[0005] Therefore, the development of high-performance magnesium alloy anodic materials has become one of the hotspots and difficulties in the research of magnesium-air batteries, and is also the key to improving their discharge performance. There is an urgent need to design new magnesium-based anodic materials with high reaction activity, slow corrosion rate and high anodic utilization rate to solve the bottleneck between the discharge voltage and the anodic efficiency. Summary of the Invention

[0006] To solve the above technical problems, the present invention proposes a heterostructure Mg-Sc-Y anodic material, a battery, an application and a preparation method thereof to solve the contradiction between the actual discharge voltage and the energy conversion efficiency in the current application of magnesium-air batteries.

[0007] To achieve the above object, the present invention provides a heterostructure Mg-Sc-Y anodic material, comprising the following components by mass percentage: scandium: 0.1%, yttrium: 0.1%, and the balance is magnesium.

[0008] In a possible implementation manner, the heterostructure Mg-Sc-Y anodic material has a heterogeneous microstructure and is composed of elongated deformed grains and fine equiaxed grains.

[0009] In a possible implementation, the average grain size of the fine equiaxed grains is 1.30 ± 0.01 μm, and the grain aspect ratio of the elongated deformed grains is 6.73 ± 0.05.

[0010] The present invention also provides a method for preparing the above heterogeneous structure Mg-Sc-Y anode material, comprising the following steps:

[0011] (1) Under a protective atmosphere, melt magnesium blocks, magnesium scandium master alloy and magnesium yttrium master alloy to obtain an alloy liquid, stir and let stand, skim off the surface scum, add a refining agent to the alloy liquid for refining, and after the refining is completed, carry out casting and cooling in sequence to obtain a Mg-Sc-Y alloy ingot;

[0012] (2) Under a protective atmosphere, perform a two-stage solution treatment on the Mg-Sc-Y alloy ingot to obtain a solution matrix;

[0013] (3) Extrude the solution matrix to obtain an extruded bar, which is the heterogeneous structure Mg-Sc-Y anode material.

[0014] In a possible implementation, in step (1), the protective atmosphere is carbon dioxide and sulfur hexafluoride, and the volume ratio of carbon dioxide to sulfur hexafluoride is (35 - 45)∶1;

[0015] In step (2), the protective atmosphere is argon.

[0016] In a possible implementation, in step (1), the refining agent is a mixture of MgCl2, KCl, BaCl2 and CaF2, and the mass ratio of MgCl2, KCl, BaCl2 and CaF2 is 46∶40∶8∶6;

[0017] The temperature of the refining is 740 °C, and the time of the refining is 1 - 2 min.

[0018] In a possible implementation, in step (2), the steps of the two-stage solution treatment are: the first solution treatment and the second solution treatment carried out in sequence;

[0019] The temperature of the first solution treatment is 310 - 330 °C, and the holding time of the first solution treatment is 50 - 70 min;

[0020] The temperature of the second solution treatment is 480 - 520 °C, and the holding time of the second solution treatment is 350 - 370 min.

[0021] In a possible implementation, in step (3), the temperature of the extrusion treatment is 240 - 250 °C, the speed of the extrusion treatment is 0.08 - 0.12 mm / s, and the extrusion ratio is 15:1 - 17:1.

[0022] The present invention also provides an application of the above heterogeneous structure Mg-Sc-Y anode material in a magnesium-air battery.

[0023] The present invention also provides a magnesium-air battery comprising the above heterogeneous structure Mg-Sc-Y anode material.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] The present invention provides a heterogeneous structure Mg-Sc-Y anode material, comprising components in the following mass percentages: magnesium: 99.8%, scandium: 0.1%, yttrium: 0.1%. By doping appropriate amounts of rare earth elements Sc and Y into the pure magnesium anode for microalloying, the present invention changes the microstructure of the magnesium alloy. The Sc element and the Y element have a high solid solubility in the Mg matrix. The Sc and Y atoms can simultaneously improve the chemical activity during the discharge process and the corrosion resistance of the matrix, achieving a synergistic improvement in the discharge voltage and the anode efficiency; at the same time, the addition of rare earth elements also significantly refines the grains and effectively activates the discharge process. The content of the added alloying elements does not exceed 0.1%, which not only reduces the production cost of the magnesium anode material but also does not generate a second phase, greatly reducing the thermodynamic tendency of microgalvanic corrosion.

[0026] The heterogeneous structure Mg-Sc-Y anode material has no precipitation phase, and through the foregoing processing technology for tissue regulation, a heterogeneous structure is formed, that is, it is composed of elongated deformed grains and fine equiaxed grains; the average grain size of the fine grains is 1.30 ± 0.01 μm, and the grain aspect ratio of the deformed coarse grains is 6.73 ± 0.05.

[0027] The heterogeneous structure Mg-Sc-Y anode material provided by the present invention realizes a synergistic improvement in the discharge voltage and the anode efficiency.

[0028] The present invention uses magnesium blocks, magnesium-scandium master alloys, and magnesium-yttrium master alloys as raw materials, and through melting, refining, double-stage solution treatment, and extrusion treatment, prepares a magnesium-air battery anode material with excellent discharge performance. This preparation method has a short process flow, is simple and efficient, and has a low preparation cost.

[0029] The present invention adopts a process flow of directly extruding after double-stage solution treatment, shortening the preparation process. After extrusion treatment, a heterogeneous microstructure is achieved, improving the comprehensive discharge performance of the magnesium-air battery anode material.

[0030] After the solid solution matrix is subjected to extrusion treatment, a heterogeneous lamellar mixed crystal structure is obtained, which significantly improves the anodic dissolution kinetics, effectively inhibits anodic hydrogen evolution and mass effect, and enhances the discharge performance of the battery.

[0031] When the anode material of the low-alloyed magnesium-air battery provided by the present invention is applied to a magnesium-air battery and used as an anode, at a current density of 0.5 mA·cm -2 , the discharge voltage is 1.6482 V, and the anode utilization rate is 33.44%. At a current density of 10 mA·cm -2 , the discharge voltage reaches 1.4252 V, the anode utilization rate is 60.23%, and the energy density reaches 1915.59 mW·h·g -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 It is the metallographic microstructure diagram of the heterogeneous structure Mg-Sc-Y anode material obtained in Example 1 of the present invention;

[0034] Figure 2 It is the average grain size diagram of the fine grains of the heterogeneous structure Mg-Sc-Y anode material statistically obtained in Example 1 of the present invention;

[0035] Figure 3 It is the characterization result diagram of the heterogeneous structure Mg-Sc-Y anode material obtained in Example 1 of the present invention; wherein, a is the SEM microstructure diagram, and b is the XRD diagram;

[0036] Figure 4 It is the potentiodynamic polarization test diagram of the heterogeneous structure Mg-Sc-Y anode material obtained in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation manners of the present invention.

[0038] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0039] The "magnesium ingot", "magnesium-scandium master alloy", and "magnesium-yttrium master alloy" used in this article are all high-purity metal materials, which can be obtained by those skilled in the art through commercial channels; preferably, the purity of the magnesium ingot is greater than 99.9 wt.%, the magnesium-scandium master alloy is 80.0 wt.% Mg - 20.0 wt.% Sc, and the magnesium-yttrium master alloy is 70.0 wt.% Mg - 30.0 wt.% Y.

[0040] The present invention provides a heterogeneous structure Mg-Sc-Y anode material, comprising the following components by mass percentage: magnesium: 99.8%, scandium: 0.1%, yttrium: 0.1%.

[0041] In one embodiment, the purity of the magnesium is preferably > 99.9%, the Mg-20.0 wt.% Sc master alloy, the Mg-30.0 wt.% Y master alloy, and the oxide scale on the surface is polished off.

[0042] The present invention also provides a method for preparing the heterogeneous structure Mg-Sc-Y anode material, comprising the following steps:

[0043] (1) Under a protective atmosphere, the high-purity magnesium ingot, high-purity magnesium-scandium master alloy, and high-purity magnesium-yttrium master alloy are melted to obtain an alloy liquid, a refining agent is added to the alloy liquid for refining, and after the refining is completed, casting and cooling are sequentially carried out to obtain an ingot;

[0044] (2) Under a protective atmosphere, the ingot is subjected to a two-stage solution treatment to obtain a solution matrix;

[0045] (3) The solution matrix is subjected to extrusion treatment to obtain an extruded bar.

[0046] In one embodiment, the high-purity magnesium ingot, high-purity magnesium-scandium master alloy, and high-purity magnesium-yttrium master alloy all need to be dried before use. The temperature of the drying treatment is preferably 180 - 220 °C, more preferably 190 - 210 °C, and even more preferably 195 - 205 °C. The heat preservation time for drying is preferably 100 - 140 min, more preferably 110 - 130 min, and even more preferably 115 - 125 min.

[0047] In one embodiment, in step (1), when the temperature of the resistance furnace is raised to 400 °C, part of the magnesium ingot is placed in the crucible, and a protective gas is introduced to form a protective atmosphere.

[0048] In one embodiment, the crucible needs to be pretreated before use. The steps of the pretreatment are as follows: Place the crucible on an electric resistance furnace at a temperature of 300 °C and keep it warm for 20 min. After the heat preservation is completed, take out the crucible and evenly apply a coating on the surface of the crucible. The number of times of application is preferably 3 times, and the components of the coating are preferably zinc oxide, water and sodium silicate. The mass-volume ratio of zinc oxide, water and sodium silicate is preferably 22.5 g: 120 mL: 22.5 g.

[0049] In one embodiment, the protective atmosphere in step (1) is preferably carbon dioxide and sulfur hexafluoride, and the volume ratio of carbon dioxide to sulfur hexafluoride is preferably (35 - 45): 1, more preferably (37 - 43): 1, and still more preferably (39 - 41): 1.

[0050] In one embodiment, after introducing a protective gas to form a protective atmosphere, adjust the temperature of the electric resistance furnace to the melting temperature. After the magnesium block melts to form molten magnesium, use a slag skimmer to remove the oxide film on the surface of the molten magnesium, and then add the magnesium-scandium master alloy to the molten magnesium, and then press one of the remaining magnesium blocks onto the surface of the magnesium-scandium master alloy for melting.

[0051] In one embodiment, the mass of the remaining magnesium block is greater than that of the magnesium-scandium master alloy. The purpose of pressing one of the remaining magnesium blocks onto the surface of the magnesium-scandium master alloy is to press the magnesium-scandium master alloy below the molten magnesium surface to promote the full melting of the magnesium-scandium master alloy.

[0052] In one embodiment, the slag skimmer needs to be pretreated before use. The steps of the pretreatment are as follows: Place the slag skimmer on an electric resistance furnace at a temperature of 300 °C and keep it warm for 20 min. After the heat preservation is completed, take out the slag skimmer and evenly apply a coating on the surface of the slag skimmer. The number of times of application is preferably 3 times, and the components of the coating are preferably zinc oxide, water and sodium silicate. The mass-volume ratio of zinc oxide, water and sodium silicate is preferably 22.5 g: 120 mL: 22.5 g.

[0053] In one embodiment, the melting temperature in step (1) is preferably 710 - 750 °C, more preferably 720 - 740 °C, and still more preferably 725 - 735 °C.

[0054] In one embodiment, after the magnesium-scandium master alloy melts to obtain an alloy liquid, adjust the temperature of the electric resistance furnace to the melting temperature again. After the magnesium block melts to form molten magnesium, use a slag skimmer to remove the oxide film on the surface of the molten magnesium, and then add the magnesium-yttrium master alloy to the molten magnesium, and then press the last remaining magnesium block onto the surface of the magnesium-yttrium master alloy for melting.

[0055] In one embodiment, the pretreatment and the preferred temperature of the slag skimmer during use are as above.

[0056] In one embodiment, after the magnesium-yttrium master alloy is melted to obtain the alloy liquid, the system temperature is adjusted to the refining temperature for refining.

[0057] In one embodiment, the refining agent in step (1) is a mixture of MgCl2, KCl, BaCl2 and CaF2, and the mass ratio of MgCl2, KCl, BaCl2 and CaF2 is 46:40:8:6;

[0058] The temperature of the refining is preferably 740 °C, the time of the refining is preferably 1 - 2 min, more preferably 1.2 - 1.8 min, and still more preferably 1.4 - 1.6 min.

[0059] In one embodiment, a stirring rod is used to stir the alloy liquid during the refining process.

[0060] In one embodiment, the stirring rod needs to be pretreated before use. The steps of the pretreatment are as follows: Place the stirring rod on an electric resistance furnace at a temperature of 300 °C and keep it warm for 20 min. After the heat preservation is completed, take out the stirring rod and evenly apply a coating on the surface of the stirring rod. The number of times of the application is preferably 3 times, and the components of the coating are preferably zinc oxide, water and sodium silicate. The mass-volume ratio of zinc oxide, water and sodium silicate is preferably 22.5 g:120 mL:22.5 g.

[0061] In one embodiment, after the refining is completed, the temperature is adjusted to the melting temperature for heat preservation. After the heat preservation is completed, the system temperature is adjusted to the temperature for slag skimming treatment for slag skimming treatment. The time of the heat preservation is preferably 15 - 25 min, more preferably 17 - 23 min, and still more preferably 19 - 21 min; the temperature of the slag skimming treatment is preferably 700 - 720 °C, more preferably 705 - 715 °C, and still more preferably 708 - 712 °C.

[0062] In one embodiment, the tool for slag skimming treatment is a slag skimming spoon, and the purpose of the slag skimming treatment is to remove the oxide film on the surface of the alloy liquid.

[0063] In one embodiment, the slag skimming spoon needs to be pretreated before use. The steps of the pretreatment are as follows: Place the slag skimming spoon on an electric resistance furnace at a temperature of 300 °C and keep it warm for 20 min. After the heat preservation is completed, take out the slag skimming spoon and evenly apply a coating on the surface of the slag skimming spoon. The number of times of the application is preferably 3 times, and the components of the coating are preferably zinc oxide, water and sodium silicate. The mass-volume ratio of zinc oxide, water and sodium silicate is preferably 22.5 g:120 mL:22.5 g.

[0064] In one embodiment, after the slag skimming treatment, the alloy liquid is poured into a mold for casting to obtain a blank. The material of the mold is preferably copper, and the mold needs to be preheated before use. The temperature of the preheating treatment is preferably 200 °C.

[0065] In one embodiment, the cooling method in step (1) is preferably air static cooling.

[0066] In one embodiment, the protective atmosphere in step (2) is preferably argon.

[0067] In one embodiment, the double-stage solution treatment in step (2) is carried out in a heat treatment furnace of model OTF-1200X.

[0068] In one embodiment, the specific steps of the double-stage solution treatment in step (2) are preferably: the first solution treatment and the second solution treatment carried out in sequence;

[0069] The temperature of the first solution treatment is preferably 310 - 330 °C, more preferably 315 - 325 °C, and even more preferably 317 - 323 °C. The holding time of the first solution treatment is preferably 50 - 70 min, more preferably 55 - 65 min, and even more preferably 58 - 62 min;

[0070] The temperature of the second solution treatment is preferably 480 - 520 °C, more preferably 490 - 510 °C, and even more preferably 495 - 515 °C. The holding time of the second solution treatment is preferably 350 - 370 min, more preferably 355 - 365 min, and even more preferably 357 - 363 min.

[0071] In one embodiment, after the double-stage solution treatment is completed, water quenching is carried out to obtain a solution matrix.

[0072] In one embodiment, the solution matrix is machined into an extrusion blank, and then extrusion treatment is carried out to obtain an extrusion bar. The temperature of the extrusion treatment is preferably 245 °C, and the extrusion ratio of the extrusion treatment is preferably 16:1.

[0073] The present invention also provides an application of a heterogeneous structure Mg-Sc-Y anode material in a magnesium-air battery.

[0074] The present invention also provides a magnesium-air battery, including the above heterogeneous structure Mg-Sc-Y anode material.

[0075] Example 1

[0076] The high-purity magnesium block, high-purity Mg-Sc master alloy and high-purity Mg-Y master alloy are placed in an oven and dried at 200 °C for 2 h for standby.

[0077] Place the crucible on an electric resistance furnace at a temperature of 300 °C and keep it warm for 20 min. After the heat preservation ends, take out the crucible and evenly apply the coating on the surface of the crucible 3 times. The coating consists of zinc oxide, water and sodium silicate, and the mass-volume ratio of zinc oxide, water and sodium silicate is 22.5 g: 120 mL: 22.5 g.

[0078] Place the slag skimmer on an electric resistance furnace at a temperature of 300 °C and keep it warm for 20 min. After the heat preservation ends, take out the slag skimmer and evenly apply the coating on the surface of the slag skimmer 3 times. The coating consists of zinc oxide, water and sodium silicate, and the mass-volume ratio of zinc oxide, water and sodium silicate is 22.5 g: 120 mL: 22.5 g.

[0079] Place the stirring rod on an electric resistance furnace at a temperature of 300 °C and keep it warm for 20 min. After the heat preservation ends, take out the stirring rod and evenly apply the coating on the surface of the stirring rod 3 times. The coating consists of zinc oxide, water and sodium silicate, and the mass-volume ratio of zinc oxide, water and sodium silicate is 22.5 g: 120 mL: 22.5 g.

[0080] Heat up the electric resistance furnace to 400 °C. Put 365.2 g of pre-treated magnesium blocks into the pre-treated crucible. Introduce a mixed gas of carbon dioxide and sulfur hexafluoride (the volume ratio of carbon dioxide to sulfur hexafluoride is 40:1). After forming a protective atmosphere, adjust the temperature of the electric resistance furnace to 710 °C and keep it warm for 25 min. The magnesium blocks melt to form molten magnesium. Use the slag skimmer to remove the oxide film on the surface of the molten magnesium. Then add the pre-treated magnesium-scandium master alloy. Press the second 65.0 g of pre-treated magnesium block onto the surface of the magnesium-scandium master alloy. After the magnesium-scandium master alloy and the magnesium blocks melt to obtain the alloy liquid, adjust the temperature to the melting temperature of the alloy again. Then add the magnesium-yttrium master alloy into the molten magnesium, and press the remaining magnesium block onto the surface of the magnesium-yttrium master alloy for melting. Then lower the temperature of the system to 740 °C, add the refining agent (the mass ratio of MgCl2, KCl, BaCl2 and CaF2 is 46∶40∶8∶6), and at the same time use the stirring rod to stir the alloy liquid for 2 min for refining treatment. After the refining ends, adjust the temperature to 740 °C and keep it warm at 740 °C for 20 min. After the heat preservation ends, adjust the system temperature to 710 °C for slag skimming treatment to remove the oxide film on the surface of the alloy liquid. After the slag skimming treatment ends, under the condition of a mixed gas of carbon dioxide and sulfur hexafluoride (the volume ratio of carbon dioxide to sulfur hexafluoride is 40:1), pour the alloy liquid into a preheated copper mold at 200 °C for casting to obtain a blank. The blank is left to cool in the air to obtain an ingot.

[0081] Under an argon atmosphere, the ingot was placed in a heat treatment furnace of model OTF-1200X for double-stage solution treatment. Among them, the first-stage solution treatment was carried out at a temperature of 320 °C for 60 min, and the second-stage solution treatment was carried out at a temperature of 500 °C for 360 min. After the double-stage solution treatment was completed, water quenching was carried out to obtain a solution matrix.

[0082] The solution matrix was machined into an extrusion blank with a diameter of 40 mm and a height of 50 mm, and then hot extrusion was carried out at 245 °C with an extrusion ratio of 16:1 to obtain an extruded bar, which is the heterogeneous structure Mg-Sc-Y anode material.

[0083] Performance test

[0084] The heterogeneous structure Mg-Sc-Y anode material obtained in Example 1 was placed under a metallurgical microscope for observation. The specific crystal phase structure diagram is as Figure 1 shown. From Figure 1 it can be seen that the heterogeneous structure Mg-Sc-Y anode material provided by the present invention has no precipitation phase, and the metallurgical structure is composed of fine equiaxed grains and deformed coarse grains.

[0085] The average grain size of the fine grains of the heterogeneous structure Mg-Sc-Y anode material obtained in Example 1 was tested. The results are as Figure 2 shown. According to the Nano measure test software, the average grain size was tested to be 1.30 ± 0.01 μm, and the aspect ratio of the deformed coarse grains was 6.73 ± 0.01.

[0086] The heterogeneous structure Mg-Sc-Y anode material obtained in Example 1 was characterized and tested, as Figure 3 shown. Among them Figure 3 a is the SEM microstructure diagram, Figure 3 b in Figure 3 is the XRD diagram. From

[0087] A typical three-electrode system electrochemical workstation of model CS350H from Wuhan Kost was used for electrochemical testing. Among them, the platinum sheet was the auxiliary electrode, the heterogeneous structure Mg-Sc-Y anode material prepared in Example 1 of the present invention was the working electrode, and the saturated calomel electrode was the reference electrode. The electrolyte used was a 3.5 wt% NaCl solution.

[0088] Electrochemical tests include open circuit potential tests, impedance spectroscopy tests, and potentiodynamic polarization tests. The tests are carried out according to the following procedure. First, the open circuit potential test is performed for 1 h. After the open circuit potential stabilizes, the impedance spectroscopy test is carried out with a set frequency of 100 kHz - 10 mHz and a voltage of 5 mV. Finally, the potentiodynamic polarization test is performed with a scanning rate of 0.1 mV / s and a scanning range from -2.4 V to -1 V. The specific results are as Figure 4 shown. Combining with the CorShow software to analyze the polarization curve, the slope of the anodic branch of the polarization curve is 54.66, the slope of the cathodic branch of the polarization curve is 321.74, and the corrosion current density is 369.69 μA / cm 2 .

[0089] Example 2

[0090] Same as Example 1, except that after the double-stage solution treatment of the anode material, it is not extruded.

[0091] Example 3

[0092] Same as Example 1, except that the cooled ingot is not subjected to double-stage solution treatment and extrusion treatment.

[0093] Example 4

[0094] Same as Example 1, except that the anode material is changed to Mg-Sc-In alloy, and its mass percentage composition is magnesium: 99.8%, scandium: 0.1%, indium: 0.1%. The same process is used during the preparation.

[0095] Example 5

[0096] Same as Example 1, except that the anode material is replaced with remelted high-purity magnesium for the same homogenization treatment and extrusion treatment.

[0097] The anode materials obtained in Examples 1-5 are used as the anodes of the air magnesium battery.

[0098] The performance of Example 1 is tested at different discharge current densities, and the results are shown in Table 1.

[0099] Table 1 Performance test results of Example 1 at different discharge current densities

[0100]

[0101] It can be seen from Table 1 that the energy density of the heterostructure Mg-Sc-Y anode material provided by the present invention increases with the increase of the current density, and the highest data in the table is 1915.59 mW·h·g -1 .

[0102] Test Example 1 and the remaining examples as anode materials at a discharge current density of 10 mA·cm -2 The battery performance under the given conditions. The results are shown in Table 2.

[0103] Table 2 Test results of the battery performance of Examples 1 - 5 at a discharge current density of 10 mA·cm -2

[0104]

[0105] As can be seen from Table 2, at 10 mA·cm -2 The heterostructure Mg - Sc - Y anode material provided by the present invention exhibits more excellent average discharge voltage, anode efficiency and energy density compared with other examples, and is a magnesium - air battery electrode material with great development potential.

[0106] The above - described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.​

Claims

1. A preparation method of a heterogeneous structure Mg-Sc-Y anode material, characterized in that, It includes the following steps: (1) Under a protective atmosphere, melt magnesium blocks, magnesium scandium master alloy and magnesium yttrium master alloy to obtain an alloy liquid, stir and let it stand, skim off the surface scum, add a refining agent to the alloy liquid for refining. After the refining is completed, carry out casting and cooling in sequence to obtain a Mg-Sc-Y alloy ingot; (2) Under a protective atmosphere, perform a two-stage solution treatment on the Mg-Sc-Y alloy ingot to obtain a solution matrix; (3) Perform extrusion treatment on the solution matrix to obtain an extruded bar, which is a heterogeneous structure Mg-Sc-Y anode material; The heterogeneous structure Mg-Sc-Y anode material includes the following components by mass percentage: scandium: 0.1%, yttrium: 0.1%, and the balance is magnesium; The heterogeneous structure Mg-Sc-Y anode material has a heterogeneous microstructure, which is composed of elongated deformed grains and fine equiaxed grains; the average grain size of the fine equiaxed grains is 1.30±0.01μm, and the grain aspect ratio of the elongated deformed grains is 6.73±0.05; The heterogeneous structure Mg-Sc-Y anode material only has a single α-Mg phase and no precipitation phase; In step (1), the protective atmosphere is carbon dioxide and sulfur hexafluoride, and the volume ratio of carbon dioxide to sulfur hexafluoride is 40:1; In step (2), the protective atmosphere is argon; In step (1), the refining agent is a mixture of MgCl2, KCl, BaCl2 and CaF2, and the mass ratio of MgCl2, KCl, BaCl2 and CaF2 is 46:40:8:6; The temperature of the refining is 740°C, and the refining time is 1-2 min; In step (2), the steps of the two-stage solution treatment are: the first solution treatment and the second solution treatment carried out in sequence; The temperature of the first solution treatment is 320°C, and the holding time of the first solution treatment is 60 min; The temperature of the second solution treatment is 500°C, and the holding time of the second solution treatment is 360 min; In step (3), the temperature of the extrusion treatment is 245°C, the extrusion speed is 0.08-0.12 mm / s, and the extrusion ratio is 16:1.

Images