A microalloyed magnesium alloy anode material and a preparation method and application thereof

Abstract

This invention discloses a microalloyed magnesium alloy anode material, its preparation method, and its application. The microalloyed magnesium alloy anode material comprises the following components by mass percentage: 1.2%–1.5% aluminum, 0.42%–0.49% manganese, 0.08%–0.20% calcium, no more than 0.05% impurities, and the balance magnesium. This invention employs a low-alloying, rare-earth-free microalloying design, adding a very small amount of non-rare-earth elements to pure magnesium. While considering the cost of magnesium alloy anodes, it achieves good performance and high production efficiency in the plastic forming of magnesium alloy anode materials. The magnesium alloy produced by this invention through microalloying design has excellent forming performance, and the preparation method is suitable for large-scale factory production. It can meet the high-efficiency production requirements of rapid extrusion and rapid rolling, and can also meet the requirements of engineers for different shapes and precision of magnesium alloy anode materials in actual production, further improving the performance of magnesium-air batteries prepared from magnesium alloy anode materials.

Description

Technical Field

[0001] This invention relates to the field of electrode materials technology, specifically to a micro-alloyed magnesium alloy anode material, its preparation method, and its application. Background Technology

[0002] With increasing resource scarcity and environmental pollution, the global energy structure is transitioning towards cleaner energy sources, necessitating the urgent development and utilization of new clean energy sources. Developing advanced new energy batteries is a crucial way to reduce CO2 emissions. Magnesium, as a abundant and inexpensive metal resource, has attracted significant attention from various industries in recent years, with my country consistently ranking among the world's top producers of magnesium products. Magnesium has a relatively low standard electrode potential (-2.37V), and magnesium-air batteries possess a large theoretical specific capacity (2205 A.h / kg) and power density (6800 mWh / g). As a battery using magnesium alloy as the anode material, magnesium-air batteries have broad application prospects in emergency rescue, marine exploration, and military applications. Currently, they are used as power sources for mobile electronic devices, underwater instruments, and small vehicles, as well as as backup and emergency power supplies in schools and hospitals. However, the magnesium alloy anode, a crucial component of magnesium-air batteries, currently faces numerous challenges. On the one hand, improving the performance of magnesium anodes often involves microalloying metallic magnesium. However, existing magnesium anode microalloying technologies tend to add expensive rare earth elements or a high proportion of various different elements, resulting in extremely high production costs and hindering large-scale application. On the other hand, existing magnesium anode composition design often does not consider the ease and efficiency of actual production. Plastic forming of magnesium alloy cast rods, such as extrusion or rolling, can reduce casting defects, refine grains, and improve anode performance while shaping the magnesium alloy into a pre-designed form. However, the magnesium alloy cast rods involved in existing microalloying often suffer from poor formability or slow forming speed during extrusion or rolling. Therefore, most existing technologies produce at slow speeds or, to avoid cracking during forming, simply use cast magnesium alloys as magnesium anodes.

[0003] Chinese patent CN115874100A discloses a magnesium-air battery anode material. The method involves adding pure zinc and a Mg-Er master alloy to commercially pure magnesium in a specific ratio using a casting process to prepare a Mg-Zn-Er alloy system. This patent achieves a magnesium-air battery material with good discharge performance, characterized by reduced self-corrosion and minimal accumulation of discharge products, using only traditional casting technology. However, this patent only considers the casting process for preparing the magnesium-air battery anode without subsequent deformation processes such as extrusion or rolling. Therefore, the magnesium alloy prepared by this patent is prone to accumulating numerous casting defects, making it difficult to control the discharge performance of the magnesium alloy electrode in large-scale production applications. Furthermore, the addition of the rare earth element Er is relatively expensive, making large-scale application difficult when cost is a consideration.

[0004] Chinese patent CN114990400B discloses a magnesium-air battery anode material prepared by a low-alloying and plastic deformation composite process, with a composition of Mg-Bi-Sn-In. It effectively reduces the "bulk effect" and, to some extent, inhibits the hydrogen evolution reaction, while also suppressing the formation of a dense passivation film and promoting anode activation. Although this patent involves low-alloying of the magnesium alloy electrode, reducing the content of alloying elements, the added elements, such as In, are relatively expensive. Therefore, the total cost of this patent's micro-alloying is not reduced despite the decrease in the amount of added elements. Furthermore, the extrusion speed of the magnesium alloy electrode manufacturing process involved in this patent is relatively slow, only 0.1 mm·s. -1 This is not conducive to reducing time costs, resulting in low production efficiency and making it difficult to achieve large-scale, high-efficiency production.

[0005] Chinese patent CN114990400B discloses a magnesium alloy anode material and its preparation method for marine emergency reserve batteries. The magnesium-air battery anode prepared by this patent has an alloy composition of Mg, Al, Zn, Mn, Ca, and rare earth elements. It produces a magnesium alloy electrode with a protective discharge film through slow extrusion, exhibiting high anode efficiency and excellent discharge activity. However, this patent requires the addition of rare earth elements such as Nd and Re, with Re being one of the rarest elements in the world. The addition of rare earth elements significantly increases the preparation cost, making the electrode extremely expensive and difficult to mass-produce. Furthermore, due to the high content of this alloy composition, molding during extrusion is difficult, leading to cracking and limiting the extrusion speed, which further hinders the practical application of this type of magnesium alloy anode.

[0006] Chinese patent CN115011852A discloses a magnesium alloy anode material for seawater batteries and its preparation method, with a composition of Mg-Al-Zn-Nd-Mn. This patent achieves excellent discharge performance and easy desorption of discharge products using a casting process, resulting in a rare-earth magnesium alloy material. However, this patent employs a high-alloy design for the magnesium alloy, with a high proportion of Al and Zn alloying elements, and also adds the rare-earth element Nd, thus resulting in extremely high casting costs. Furthermore, due to the high proportion of alloying elements, the magnesium alloy involved in this patent is not suitable for plastic forming and can only be processed using a casting process. Therefore, the magnesium anode involved in this patent was only tested using as-cast magnesium anode samples.

[0007] Chinese patent CN112993274A discloses a magnesium alloy anode material for marine equipment and its preparation method. This patent achieves a low self-corrosion rate and high anode utilization rate through the synergistic effect of multiple alloy components. However, the magnesium alloy composition of this patent is Mg-Al-Zn-Mn-Re-Bi-Sn-In-Ga, which is complex, difficult to melt, and hard to control in terms of melting effect. It also uses several relatively expensive elements, such as the rare earth element Re and the precious metal In. Furthermore, the high alloy content of the magnesium alloy anode in this patent makes plastic forming difficult, requiring an inefficient and costly plastic forming method. This involves extruding the magnesium alloy casting and then performing multiple rolling passes. Therefore, the magnesium anode material in this patent is unlikely to improve efficiency in industrial production and will be difficult to popularize in practical applications.

[0008] Currently, there is an urgent need to invent a technology that can achieve good magnesium anode performance and high production efficiency in magnesium alloy plastic forming while taking cost into account. Summary of the Invention

[0009] To address the aforementioned technical problems, the present invention aims to provide a micro-alloyed magnesium alloy anode material. Unlike existing technologies that mostly favor adding expensive rare earth elements or adding a high proportion of multiple elements to pure magnesium to improve the discharge performance of magnesium alloy as anode in magnesium-air batteries, the present invention adopts a micro-alloying design, that is, adding a very small amount (total micro-alloying content less than 4.5 wt%) of non-rare earth elements to pure magnesium.

[0010] A further objective of this invention is to provide a method for preparing the aforementioned microalloyed magnesium alloy anode material. The magnesium alloy produced by this invention through microalloying exhibits excellent formability, meeting the demands of high-efficiency production such as rapid extrusion and rapid rolling, and possessing the deformation capability to transform a magnesium alloy ingot into a thin sheet through a single extrusion pass. By employing microalloying design and a matching one-step high-efficiency production mode, high-performance, high-efficiency magnesium alloy anode materials can be obtained while maintaining low smelting costs.

[0011] The third objective of this invention is to provide an application of the above-mentioned microalloyed magnesium alloy anode material in the preparation of magnesium-air batteries. The microalloyed magnesium alloy anode material serves as the anode of the magnesium-air battery, and the performance of the magnesium alloy anode directly affects the discharge performance of the magnesium-air battery.

[0012] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0013] A microalloyed magnesium alloy anode material comprising the following components by mass percentage: 1.2% to 1.5% aluminum (Al), 0.42% to 0.49% manganese (Mn), 0.08% to 0.20% calcium (Ca), no more than 0.05% impurities, and the balance magnesium (Mg).

[0014] This invention employs a microalloying design, specifically adding a very small amount (total microalloying content less than 4.5 wt%) of non-rare earth elements to pure magnesium to form a Mg-Al-Mn-Ca alloy. All elements have low prices, allowing for better control of smelting costs. The trace amounts of Al and Mn elements in the magnesium alloy anode material of this invention can refine the magnesium alloy grains during smelting and plastic forming. Refined magnesium alloy grains mean a higher grain boundary density on the alloy surface. Grain boundaries, as crystal defects, possess higher energy than the interior of the crystal. A higher grain boundary density not only facilitates the self-detachment of oxidation products during discharge, resulting in a higher and more stable discharge voltage, but also allows the abundant grain boundaries to act as a barrier against the spread of corrosion on the magnesium matrix surface, reducing the self-corrosion rate of the magnesium alloy, mitigating the "block effect," and thus improving the anode utilization rate of the magnesium alloy anode.

[0015] Furthermore, during the smelting process, impurity elements inevitably infiltrate the magnesium matrix, increasing the self-corrosion rate of the magnesium alloy anode and thus reducing its anode utilization rate. An appropriate amount of Mn can effectively reduce the impact of impurity elements on magnesium alloys. However, when too much Mn is added (>0.49%), a large amount of Al-Mn will be generated in the alloy. The Al-Mn phase is a high-temperature resistant second phase that is often very coarse and unevenly distributed. It is difficult to dissolve it back into the magnesium matrix through hot working or heat treatment processes during preparation. Therefore, too much Mn should not be added.

[0016] Since the standard electrode potential of magnesium is -2.37V and that of calcium (Ca) is -2.76V, the addition of trace amounts of Ca can effectively improve the surface activity of magnesium alloy anodes. Furthermore, the addition of Ca can weaken the surface texture of magnesium alloys after plastic forming such as extrusion or rolling, ensuring that the grain orientation of the working surface of the magnesium anode is non-basal plane orientation. This non-basal plane grain orientation is beneficial to the active dissolution of the magnesium alloy anode. However, the proportion of Ca in the magnesium alloy anode is noteworthy. When the Ca content is low (≤0.08%), the surface activity of the magnesium alloy anode cannot be significantly improved, specifically reflected in the low constant current discharge voltage of the magnesium-air battery. Conversely, when the Ca content is high (>0.2%), the formability of the magnesium alloy will significantly decrease. Specifically, in the extrusion production of high-calcium magnesium alloys, only extremely slow discharge speeds (<1m / min) and low extrusion ratios (<30) can be used; otherwise, magnesium alloy cracking is highly likely.

[0017] Furthermore, the microalloyed magnesium alloy anode material also includes 0.2% to 0.5% copper.

[0018] The addition of trace amounts of Cu can further refine the grain size of magnesium alloys. After Cu is added, the grain nucleation mechanism of Mg-Al-Mn-Ca alloys changes during extrusion or rolling, specifically manifested in a significant reduction in the dynamic recrystallized grain size near the second-phase particles. However, because the potential of Cu is significantly higher than that of the Mg matrix, when Cu is added alone to a magnesium alloy, the potential of the Mg-Cu phase is much higher than that of the magnesium matrix. The Mg-Cu phase acts as a cathode, resulting in strong galvanic corrosion with the magnesium matrix anode, thus significantly increasing the self-corrosion rate of the magnesium alloy.

[0019] Furthermore, the microalloyed magnesium alloy anode material also includes 1.0% to 1.5% zinc.

[0020] Since the Mg-Zn-Cu phase is often relatively dispersed and uniform, while the Mg-Cu phase is relatively coarse, and although the potential of the Mg-Zn-Cu phase is slightly higher than that of the Mg matrix, it is closer to that of the Mg matrix than that of Mg-Cu, adding an appropriate amount of Zn element along with Cu element to the Mg-Al-Mn-Ca alloy, so that the Mg-Cu phase transforms into the Mg-Zn-Cu phase, can effectively reduce the discharge self-corrosion rate of magnesium alloys while controlling costs. It is important to emphasize that a small amount of Zn element should not be added to the Mg-Al-Mn-Ca-Cu alloy, because a small amount of Zn element cannot transform all the Mg-Cu phases in the alloy into the Mg-Zn-Cu phase. In this case, both Mg-Cu and Mg-Zn-Cu phases will coexist in the magnesium matrix, which is detrimental to improving the self-corrosion resistance of the magnesium alloy.

[0021] The present invention considers adding Cu alone to Mg-Al-Mn-Ca alloy to obtain smaller recrystallized grains, or adding Zn simultaneously with Cu, to further improve the self-corrosion resistance and anode utilization rate of magnesium alloy while obtaining smaller recrystallized grains.

[0022] Furthermore, the microalloyed magnesium alloy anode material comprises the following components by mass percentage: 1.2% to 1.31% aluminum, 0.42% to 0.49% manganese, 0.08% to 0.10% calcium, no more than 0.05% impurities, and the balance magnesium. In this case, the extrusion ratio in the preparation method can reach 80 to 130, and the extrusion speed can be 35 to 70 m / min.

[0023] A method for preparing a micro-alloyed magnesium alloy anode material includes the following steps:

[0024] S1. In an inert atmosphere, pure magnesium, pure aluminum, and magnesium-manganese master alloy are added to a high-temperature melting furnace and melted at 680-720°C.

[0025] S2. Add a magnesium-calcium master alloy to a high-temperature melting furnace and melt at 680–720°C. Degas and remove slag from the resulting molten metal to obtain an alloy melt; or

[0026] Magnesium-calcium master alloy and pure copper are added to a high-temperature smelting furnace and smelted at 680–720°C. The resulting molten liquid is then degassed and slag removed to obtain an alloy liquid; or

[0027] Magnesium-calcium master alloy, pure copper and pure zinc are added to a high-temperature smelting furnace and smelted at 680-720℃. The resulting molten liquid is then degassed and slag is removed to obtain an alloy liquid.

[0028] S3. Under an inert atmosphere, the alloy liquid obtained in S2 is cast into a mold and cooled to obtain a magnesium alloy ingot;

[0029] S4. After removing the oxide scale from the surface of the magnesium alloy ingot obtained in S3, it is subjected to extrusion molding to obtain the micro-alloyed magnesium alloy anode material.

[0030] This invention relates not only to the design of high-performance magnesium-air battery anode components and their proportions for rapid production, but also to the preparation method of such magnesium alloy anode materials and how to further improve their electrode performance while achieving high-efficiency preparation. According to the Zener-Hollomon theory, increasing the hot working strain rate during hot working processes such as extrusion and rolling can effectively reduce the dynamic recrystallization grain size of magnesium alloys, resulting in a significant refinement of the overall grain size. In rapid extrusion production, increasing the extrusion ratio of magnesium alloys is a method to significantly improve the hot working strain rate. However, because magnesium alloys have a close-packed hexagonal structure with few slip systems, significantly increasing the extrusion ratio on top of rapid extrusion can easily lead to cracking during production. Currently, very few magnesium alloy grades can meet the requirements for rapid extrusion, while the magnesium alloy provided by this invention can achieve an extrusion ratio significantly exceeding the conventional range (20-70) during rapid production, with a maximum extrusion ratio reaching approximately 130.

[0031] The main objective of the preparation method of this invention is to achieve good performance and high production efficiency of magnesium alloy anodes through plastic forming while considering the cost of magnesium alloy anodes. This invention provides a low-cost, high-performance magnesium alloy anode material with a complete production process from smelting to forming, suitable for large-scale, high-efficiency factory production. In practical applications, to adapt to magnesium-air battery devices, there are often precise requirements for the shape and size of magnesium alloy anodes. To meet these requirements, existing patents often require magnesium alloy anodes to undergo multiple deformation stages or time-consuming and material-intensive machining processes. The magnesium alloy anode material provided by this invention is easy to form; therefore, the predetermined shape and size requirements can be achieved through a single plastic forming process.

[0032] Furthermore, in step S1, the melting time is 15 to 30 minutes.

[0033] Furthermore, in step S2, the melting time is 15 to 30 minutes.

[0034] Furthermore, in step S3, the mold is preheated to a temperature of 400–500°C.

[0035] Further, in step S4, the extrusion ratio of the extrusion molding is 20 to 130, preferably 80 to 130.

[0036] Further, in step S4, the extrusion speed of the extrusion molding is 30-70 m / min, preferably 35-70 m / min.

[0037] Furthermore, in step S4, before the extrusion molding process, a homogenization heat treatment is also performed on the magnesium alloy ingot after removing the oxide scale.

[0038] Furthermore, the temperature of the homogenization heat treatment is 380–450°C.

[0039] Furthermore, the homogenization heat treatment time is 12 to 32 hours.

[0040] This invention also protects the application of the above-mentioned microalloyed magnesium alloy anode material in the preparation of magnesium-air batteries.

[0041] The beneficial effects of this invention are:

[0042] 1. This invention adopts a low-alloying and rare-earth-free micro-alloying design, adding a very small amount of non-rare-earth elements to pure magnesium, while taking into account the cost of magnesium alloy anodes, to obtain better magnesium alloy anode material performance and higher production efficiency of magnesium alloy anode material plastic forming.

[0043] 2. The magnesium alloy produced by the present invention through micro-alloying design has excellent forming performance. The preparation method is suitable for large-scale factory production and can meet the high-efficiency production requirements such as rapid extrusion and rapid rolling. Its extrusion ratio can significantly exceed the conventional extrusion ratio range (20-70), and the maximum extrusion ratio can reach about 130. Its extrusion speed is also much higher than the extrusion speed of existing magnesium alloys (generally less than 6m / min), and the extrusion speed can reach 30-70m / min.

[0044] 3. This invention provides a low-cost, high-performance magnesium-air battery anode material that is produced throughout the entire process from smelting to forming. Furthermore, thanks to the excellent forming performance of magnesium alloy anode materials during extrusion or rolling, the predetermined shape and size requirements can be achieved by plastic forming the magnesium alloy anode material in a single process. This better meets the requirements of engineers for different shapes and precision of magnesium alloy anode materials in actual production. Attached Figure Description

[0045] Figure 1 Images are shown of the Mg-1.24Al-0.42Mn-0.22Ca alloy of Comparative Example 1 and the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 1 after rapid extrusion molding; wherein, a is an image of the Mg-1.24Al-0.42Mn-0.22Ca alloy of Comparative Example 1 after rapid extrusion molding, and b is an image of the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 1 after rapid extrusion molding.

[0046] Figure 2The images shown are optical micrographs of the magnesium alloy anode materials of Examples 1 to 5; wherein, a is an optical micrograph of the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 1, b is an optical micrograph of the Mg-1.09Al-0.49Mn-0.10Ca-0.21Cu alloy of Example 2, c is an optical micrograph of the Mg-1.31Al-0.44Mn-0.08Ca-0.21Cu-1.00Zn alloy of Example 3, d is an optical micrograph of the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 4, and e is an optical micrograph of the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 5.

[0047] Figure 3 The images shown are scanning electron microscope (SEM) images of the magnesium alloy anode materials of Examples 1 to 5; wherein, a is an SEM image of the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 1, b is an SEM image of the Mg-1.09Al-0.49Mn-0.10Ca-0.21Cu alloy of Example 2, c is an SEM image of the Mg-1.31Al-0.44Mn-0.08Ca-0.21Cu-1.00Zn alloy of Example 3, d is an SEM image of the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 4, and e is an SEM image of the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 5.

[0048] Figure 4 The graphs show the potentiodynamic polarization curves of the magnesium alloy anode materials in Examples 1-5 and Comparative Example 3.

[0049] Figure 5 Magnesium-air batteries prepared using the magnesium alloy anode materials of Examples 1-5 and Comparative Example 2 achieved a power output of 2.5 mA·cm⁻¹. -2 The constant current discharge curve is shown below.

[0050] Figure 6 Magnesium-air batteries prepared using the magnesium alloy anode materials of Examples 1-5 and Comparative Example 2 at 5 mA·cm -2 The constant current discharge curve is shown below.

[0051] Figure 7 Magnesium-air batteries prepared using the magnesium alloy anode materials of Examples 1-5 and Comparative Example 2 at 10 mA·cm -2 The constant current discharge curve is shown below. Detailed Implementation

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0053] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0054] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0055] Example 1

[0056] A microalloyed magnesium alloy anode material, Mg-1.24Al-0.42Mn-0.08Ca alloy, comprising the following components by mass percentage: 1.24% aluminum, 0.42% manganese, 0.08% calcium, no more than 0.05% impurities, and the balance magnesium.

[0057] Example 1: The preparation method of microalloyed magnesium alloy anode material Mg-1.24Al-0.42Mn-0.08Ca alloy includes the following steps:

[0058] S1. Under an argon atmosphere, pure magnesium, pure aluminum, and magnesium-manganese master alloy are added to a high-temperature melting furnace in proportion and melted at 700°C for 15 minutes.

[0059] S2. Add magnesium-calcium master alloy to a high-temperature melting furnace and melt at 700°C for 15 minutes. Degas and remove slag from the resulting melt to obtain alloy liquid.

[0060] S3. Under an argon atmosphere, the alloy liquid obtained in S2 is poured into an ingot mold preheated to 400°C. After the metal liquid solidifies, it is naturally cooled to obtain a magnesium alloy ingot.

[0061] S4. Take out the magnesium alloy ingot from the mold obtained in S3, remove the oxide scale from the surface of the magnesium alloy ingot, and then perform homogenization heat treatment at 400℃ for 24h. Then, perform extrusion molding with an extrusion ratio of 28:1 and an extrusion speed of 35m / min to obtain a wide sheet with a thickness of 3mm and a width of 130mm. The sheet can be simply sawed to obtain microalloyed magnesium alloy anode material of the predetermined size.

[0062] Example 2

[0063] A microalloyed magnesium alloy anode material, Mg-1.09Al-0.49Mn-0.10Ca-0.21Cu alloy, comprising the following components by mass percentage: 1.09% aluminum, 0.49% manganese, 0.10% calcium, 0.21% copper, no more than 0.05% impurities, and the balance magnesium.

[0064] Example 1: The preparation method of microalloyed magnesium alloy anode material Mg-1.09Al-0.49Mn-0.10Ca-0.21Cu alloy includes the following steps:

[0065] S1. Under an argon atmosphere, pure magnesium, pure aluminum, and magnesium-manganese master alloy are added to a high-temperature melting furnace in proportion and melted at 700°C for 15 minutes.

[0066] S2. Add magnesium-calcium master alloy and pure copper to a high-temperature melting furnace and melt at 700°C for 15 minutes. Degas and remove slag from the resulting melt to obtain alloy liquid.

[0067] S3. Under an argon atmosphere, the alloy liquid obtained in S2 is poured into an ingot mold preheated to 400°C. After the metal liquid solidifies, it is naturally cooled to obtain a magnesium alloy ingot.

[0068] S4. Take out the magnesium alloy ingot from the mold obtained in S3, remove the oxide scale from the surface of the magnesium alloy ingot, and then perform homogenization heat treatment at 400℃ for 24h. Then, perform extrusion molding with an extrusion ratio of 28:1 and an extrusion speed of 35m / min to obtain a wide sheet with a thickness of 3mm and a width of 130mm. The sheet can be simply sawed to obtain microalloyed magnesium alloy anode material of the predetermined size.

[0069] Example 3

[0070] A microalloyed magnesium alloy anode material, Mg-1.31Al-0.44Mn-0.08Ca-0.21Cu-1.00Zn alloy, comprising the following components by mass percentage: 1.31% aluminum, 0.44% manganese, 0.08% calcium, 0.21% copper, 1.00% zinc, no more than 0.05% impurities, and the balance magnesium.

[0071] Example 1: The preparation method of microalloyed magnesium alloy anode material Mg-1.31Al-0.44Mn-0.08Ca-0.21Cu-1.00Zn alloy includes the following steps:

[0072] S1. Under an argon atmosphere, pure magnesium, pure aluminum, and magnesium-manganese master alloy are added to a high-temperature melting furnace in proportion and melted at 700°C for 15 minutes.

[0073] S2. Add magnesium-calcium master alloy, pure copper and pure zinc to a high-temperature melting furnace, and melt at 700°C for 15 minutes. Degas and remove slag from the resulting melt to obtain alloy liquid.

[0074] S3. Under an argon atmosphere, the alloy liquid obtained in S2 is poured into an ingot mold preheated to 400°C. After the metal liquid solidifies, it is naturally cooled to obtain a magnesium alloy ingot.

[0075] S4. Take out the magnesium alloy ingot from the mold obtained in S3, remove the oxide scale from the surface of the magnesium alloy ingot, and then perform homogenization heat treatment at 400℃ for 24h. Then, perform extrusion molding with an extrusion ratio of 28:1 and an extrusion speed of 35m / min to obtain a wide sheet with a thickness of 3mm and a width of 130mm. The sheet can be simply sawed to obtain microalloyed magnesium alloy anode material of the predetermined size.

[0076] Example 4

[0077] A microalloyed magnesium alloy anode material, Mg-1.24Al-0.42Mn-0.08Ca alloy, is prepared using the same method as in Example 1, except that the extrusion ratio is 56:1 in step S4.

[0078] Example 5

[0079] A microalloyed magnesium alloy anode material, Mg-1.24Al-0.42Mn-0.08Ca alloy, is prepared using the same method as in Example 1, except that the extrusion ratio is 113:1 in step S4.

[0080] Comparative Example 1

[0081] A microalloyed magnesium alloy anode material, Mg-1.24Al-0.42Mn-0.22Ca alloy, comprising the following components by mass percentage: 1.24% aluminum, 0.42% manganese, 0.22% calcium, no more than 0.05% impurities, and the balance magnesium.

[0082] The preparation method of the microalloyed magnesium alloy anode material Mg-1.24Al-0.42Mn-0.22Ca alloy in Comparative Example 1 includes the following steps:

[0083] S1. Under an argon atmosphere, pure magnesium, pure aluminum, and magnesium-manganese master alloy are added to a high-temperature melting furnace in proportion and melted at 700°C for 15 minutes.

[0084] S2. Add magnesium-calcium master alloy to a high-temperature melting furnace and melt at 700°C for 15 minutes. Degas and remove slag from the resulting melt to obtain alloy liquid.

[0085] S3. Under an argon atmosphere, the alloy liquid obtained in S2 is poured into an ingot mold preheated to 400°C. After the metal liquid solidifies, it is naturally cooled to obtain a magnesium alloy ingot.

[0086] S4. Take out the magnesium alloy ingot from the mold obtained in S3, remove the oxide scale from the surface of the magnesium alloy ingot, and then perform homogenization heat treatment at 400℃ for 24h. Then, perform extrusion molding with an extrusion ratio of 28:1 and an extrusion speed of 35m / min to obtain a wide sheet with a thickness of 3mm and a width of 130mm. The sheet can be simply sawed to obtain microalloyed magnesium alloy anode material of the predetermined size.

[0087] Figure 1 Images show the rapid extrusion molding results of the Mg-1.24Al-0.42Mn-0.22Ca alloy of Comparative Example 1 and the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 1; where a is an image of the Mg-1.24Al-0.42Mn-0.22Ca alloy of Comparative Example 1 after rapid extrusion molding, and b is an image of the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 1 after rapid extrusion molding. Figure 1 As can be seen from Figure a, the Mg-1.24Al-0.42Mn-0.22Ca alloy in Comparative Example 1, containing a high calcium content (>0.2%), exhibited extrusion cracking after rapid extrusion and could not be used as an anode in a magnesium-air battery; from Figure 1 As can be seen from Figure b, the Mg-1.24Al-0.42Mn-0.08Ca alloy containing an appropriate amount of calcium in Example 1 has a smooth surface without cracking after rapid extrusion. This indicates that adding a high content of Ca to the Mg-Al-Mn-Ca alloy cannot guarantee the forming of the magnesium alloy in rapid extrusion production.

[0088] Comparative Example 2

[0089] A microalloyed magnesium alloy anode material, Mg-1.24Al-0.42Mn-0.05Ca alloy, comprising the following components by mass percentage: 1.24% aluminum, 0.42% manganese, 0.05% calcium, no more than 0.05% impurities, and the balance magnesium.

[0090] The preparation method of the microalloyed magnesium alloy anode material Mg-1.24Al-0.42Mn-0.05Ca alloy in Comparative Example 2 includes the following steps:

[0091] S1. Under an argon atmosphere, pure magnesium, pure aluminum, and magnesium-manganese master alloy are added to a high-temperature melting furnace in proportion and melted at 700°C for 15 minutes.

[0092] S2. Add magnesium-calcium master alloy to a high-temperature melting furnace and melt at 700°C for 15 minutes. Degas and remove slag from the resulting melt to obtain alloy liquid.

[0093] S3. Under an argon atmosphere, the alloy liquid obtained in S2 is poured into a preheated ingot mold, and after the metal liquid solidifies, it is naturally cooled to obtain a magnesium alloy ingot.

[0094] S4. Take out the magnesium alloy ingot from the mold obtained in S3, remove the oxide scale from the surface of the magnesium alloy ingot, and then perform homogenization heat treatment at 400℃ for 24h. Then, perform extrusion molding with an extrusion ratio of 28:1 and an extrusion speed of 35m / min to obtain a wide sheet with a thickness of 3mm and a width of 130mm. The sheet can be simply sawed to obtain microalloyed magnesium alloy anode material of the predetermined size.

[0095] Compared with the Mg-1.24Al-0.42Mn-0.08Ca alloy of Example 1, the Mg-1.24Al-0.42Mn-0.05Ca alloy of Comparative Example 2 has a lower Ca content. However, an excessively low Ca content cannot effectively improve the activity of the magnesium alloy anode material and will reduce the self-corrosion resistance of the Mg-Al-Mn-Ca alloy. Therefore, an excessively low Ca content is detrimental to both constant current discharge performance and anode utilization rate.

[0096] Comparative Example 3

[0097] A microalloyed magnesium alloy anode material, Mg-1.31Al-0.44Mn-0.08Ca-0.21Cu-0.70Zn alloy, comprising the following components by mass percentage: 1.31% aluminum, 0.44% manganese, 0.08% calcium, 0.21% copper, 0.70% zinc, no more than 0.05% impurities, and the balance magnesium.

[0098] The preparation method of the microalloyed magnesium alloy anode material Mg-1.31Al-0.44Mn-0.08Ca-0.21Cu-0.70Zn alloy in Comparative Example 3 includes the following steps:

[0099] S1. Under an argon atmosphere, pure magnesium, pure aluminum, and magnesium-manganese master alloy are added to a high-temperature melting furnace in proportion and melted at 700°C for 15 minutes.

[0100] S2. Add magnesium-calcium master alloy, pure copper and pure zinc to a high-temperature melting furnace, and melt at 700°C for 15 minutes. Degas and remove slag from the resulting melt to obtain alloy liquid.

[0101] S3. Under an argon atmosphere, the alloy liquid obtained in S2 is poured into a preheated ingot mold, and after the metal liquid solidifies, it is naturally cooled to obtain a magnesium alloy ingot.

[0102] S4. Take out the magnesium alloy ingot from the mold obtained in S3, remove the oxide scale from the surface of the magnesium alloy ingot, and then perform homogenization heat treatment at 400℃ for 24h. Then, perform extrusion molding with an extrusion ratio of 28:1 and an extrusion speed of 35m / min to obtain a wide sheet with a thickness of 3mm and a width of 130mm. The sheet can be simply sawed to obtain microalloyed magnesium alloy anode material of the predetermined size.

[0103] Figure 2 These are optical micrographs of the magnesium alloy anode materials from Examples 1-5. Figure 2 As can be seen, adding trace amounts of Cu or simultaneously adding Zn and Cu to the microalloyed Mg-Al-Mn-Ca alloy can effectively refine the grains. Furthermore, thanks to the excellent formability of the Mg-Al-Mn-Ca alloy of this invention, the extrusion ratio can be increased to 113 during production. When the extrusion ratio is 113, the grains in Example 5 are further refined.

[0104] Figure 3 These are scanning electron microscope (SEM) images of the magnesium alloy anode materials from Examples 1-5. Figure 3 As can be seen, adding trace amounts of Cu or simultaneously adding Zn and Cu to low-alloyed Mg-Al-Mn-Ca alloys can introduce an appropriate amount of second phase to improve the performance of magnesium-air batteries and reduce the anodic self-corrosion rate of magnesium alloys. Specifically, the second phase in Examples 1, 4, and 5 is mainly aluminum-manganese phase; the second phase in Example 3 is mainly Mg-Cu phase; and the second phase in Example 4 is mainly Mg-Zn-Cu phase.

[0105] The magnesium alloy anode materials of Examples 1-5 and Comparative Example 3 were subjected to potentiodynamic polarization curve testing using an electrochemical workstation (Chenhua 660e) to detect their resistance to self-corrosion. The potentiodynamic polarization curve test data are shown in Table 1, and the potentiodynamic polarization curve graphs are shown in [Figure 1]. Figure 4 . Figure 4Table 1 shows the potentiodynamic polarization curves of the magnesium alloy anode materials in Examples 1-5 and Comparative Example 3. These curves primarily provide the self-corrosion potential and self-corrosion current density of each test sample (as shown in Table 1). The self-corrosion rate of the magnesium alloy anode material is mainly determined by the self-corrosion current density; the lower the self-corrosion current density, the slower the self-corrosion rate. Figure 4 As shown in Table 1, the self-corrosion current densities, arranged from smallest to largest, are Example 5, Example 3, Example 2, Example 4, Example 1, and Comparative Example 3. Therefore, the self-corrosion rates of the magnesium alloy anode materials, from slowest to fastest, are Example 5, Example 3, Example 2, Example 4, Example 1, and Comparative Example 3. This result is consistent with the anode utilization rates of the samples listed in Table 3.

[0106] Table 1

[0107]

[0108]

[0109] The discharge performance of magnesium-air batteries prepared using the magnesium alloy anode materials of Examples 1-5 and Comparative Example 2 was tested using a LAND (CT3002A) electrical performance testing equipment. The discharge performance tests were conducted in a metal-air battery testing apparatus, with commercially available air carbon material as the cathode, the magnesium alloy anode materials of Examples 1-5 and Comparative Example 2 as the anode, MnO2 as the catalyst, and a 5 wt.% NaCl aqueous solution as the electrolyte. The test temperature was room temperature. Magnesium-air batteries prepared using the magnesium alloy anode materials of Examples 1-5 and Comparative Example 2 were subjected to different current densities (2.5 mA·cm⁻¹). -2 5mA·cm -2 10mA·cm -2 Discharged for 10 hours each time, the operating voltage and anode utilization rate were obtained. The constant current discharge data are shown in Table 2, the anode utilization rate data are shown in Table 3, and the corresponding constant current discharge curves are shown in the appendix. Figures 5-7 .

[0110] Table 2

[0111]

[0112] Table 3

[0113]

[0114]

[0115] By comparing the data in Tables 2 and 3, and Figures 5-7The constant current discharge curves show that adding trace amounts of Cu to low-alloyed Mg-Al-Mn-Ca alloys, or simultaneously adding Zn and Cu, or increasing the extrusion ratio, can effectively refine the magnesium alloy grains, thereby improving the constant current discharge voltage of the magnesium alloy anode and enhancing its resistance to self-corrosion. Figure 3 Comparing b and c, it can be seen that when Cu is added alone to the Mg-Al-Mn-Ca alloy, a relatively coarse Mg-Cu phase is distributed on the magnesium alloy. However, when appropriate amounts of Zn and Cu are added simultaneously, the Mg-Cu phase is completely transformed into a fine and dispersed Mg-Zn-Cu phase with a potential closer to that of the magnesium matrix. Furthermore, the appropriate amount and uniform distribution of the Mg-Zn-Cu phase introduced by the simultaneous addition of appropriate amounts of Zn and Cu makes the corrosion products on the magnesium matrix surface more porous and easier to detach. Simultaneously, the uniformly distributed second phase facilitates the self-detachment of discharge products during discharge, thus effectively improving the discharge activity of the magnesium alloy anode.

[0116] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A microalloyed magnesium alloy anode material, characterized in that, The microalloyed magnesium alloy anode material comprises the following components by mass percentage: 1.2% to 1.5% aluminum, 0.42% to 0.49% manganese, 0.08% to 0.20% calcium, 0.2% to 0.5% copper, 1.0% to 1.5% zinc, no more than 0.05% impurities, and the balance magnesium.

2. A method for preparing the microalloyed magnesium alloy anode material according to claim 1, characterized in that, Includes the following steps: S1. Under an inert atmosphere, pure magnesium, pure aluminum, and magnesium-manganese master alloy are added to a high-temperature melting furnace and melted at 680~720 °C; S2. Add magnesium-calcium master alloy, pure copper and pure zinc to a high-temperature smelting furnace and smelt at 680~720 ℃. Degas and remove slag from the molten liquid to obtain alloy liquid. S3. Under an inert atmosphere, the alloy liquid obtained in S2 is cast into a mold and cooled to obtain a magnesium alloy ingot; S4. After removing the oxide scale from the surface of the magnesium alloy ingot obtained in S3, it is subjected to extrusion molding to obtain the micro-alloyed magnesium alloy anode material.

3. The preparation method according to claim 2, characterized in that, In step S4, the extrusion ratio of the extrusion molding is 20~130.

4. The preparation method according to claim 2, characterized in that, In step S4, the extrusion speed of the extrusion molding is 30~70 m / min.

5. The preparation method according to claim 2, characterized in that, In step S4, before extrusion molding, the magnesium alloy ingot with the oxide scale removed is subjected to a homogenization heat treatment.

6. The preparation method according to claim 5, characterized in that, The homogenization heat treatment temperature is 380~450℃.

7. The application of the microalloyed magnesium alloy anode material according to claim 1 in the preparation of magnesium-air batteries.

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