Mg-sr-in alloy anode material for magnesium-air battery and preparation method thereof

Abstract

This invention provides a Mg-Sr-In alloy anode material for magnesium-air batteries and its preparation method, relating to the field of anode material technology. The magnesium-Sr alloy anode material for magnesium-air batteries described in this invention has a chemical composition mainly of Sr, In, and Mg. By doping pure magnesium anodes with appropriate amounts of Sr and In elements for microalloying, the microstructure of the magnesium alloy is altered, enhancing the corrosion resistance of the magnesium-air battery anode, activating anode reaction kinetics, maintaining the anode activation area, suppressing the negative differential effect, and reducing self-corrosion hydrogen evolution. This allows for stable discharge while improving the battery's discharge voltage and anode efficiency, significantly extending the battery's lifespan. The Mg-Sr-In anode material of this invention has a simple preparation process, low cost, and is easy to promote and apply, making it suitable for high-power electrical equipment.

Description

Technical Field

[0001] This invention relates to the field of anode material technology, and in particular to a Mg-Sr-In alloy anode material for magnesium-air batteries and its preparation method. Background Technology

[0002] With the depletion of fossil fuels and the increasing demand for clean energy, metal-air batteries, with their high energy density and pollution-free operation, represent a promising new energy source. Magnesium and its alloys are particularly valuable due to their relatively negative standard electrode potential (-2.37V vs. SHE) and high theoretical specific energy (6.8kWh / kg). -1 Magnesium air batteries are an ideal anode for metal-air batteries. Furthermore, my country has one of the world's largest reserves of magnesium ore. Therefore, the advantages of magnesium air batteries, such as low cost, safety, cleanliness, high theoretical discharge voltage, and high energy density, make them a new type of energy storage and conversion device with great potential for large-scale application.

[0003] Magnesium-air batteries typically use neutral electrolytes, such as NaCl solution or seawater. Magnesium and its alloys are oxidized to Mg during discharge. 2+ Electrons are output to the external circuit, where an oxidation reaction occurs at the cathode, where oxygen from the air and water from the electrolyte gain electrons to generate OH-. - This is the reaction principle of magnesium-air batteries. However, in practical applications, the use of magnesium-air batteries in large-scale industrial production is severely limited. This limitation stems from two main factors: firstly, the internal resistance of the battery system, such as anode and cathode polarization; and secondly, the adsorption and accumulation of discharge products on the anode surface, isolating the anode from the electrolyte and reducing the surface reaction area, resulting in an actual operating voltage far lower than the theoretical value. Furthermore, during discharge, due to the reactive nature of magnesium, it is prone to hydrogen evolution and self-corrosion, leading to the ineffective consumption of the magnesium matrix and reducing anode efficiency.

[0004] Therefore, it is necessary to develop a magnesium alloy anode material with stable discharge, high discharge voltage, and high anode efficiency to extend the service life of magnesium-air batteries and enable their application in high-power electrical equipment. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a Mg-Sr-In alloy anode material for magnesium-air batteries and its preparation method. Using this material as the anode material for magnesium-air batteries can improve the battery's discharge voltage and anode efficiency while ensuring stable discharge, significantly extending the battery's lifespan and enabling its application in high-power electrical equipment.

[0006] The Mg-Sr-In alloy anode material for magnesium-air batteries described in this invention has the following chemical composition by mass percentage:

[0007] Sr 0.1–2.0 wt.%, In 0.1–3.0 wt.%, balance Mg and unavoidable impurities.

[0008] Furthermore, the total content of the unavoidable impurities is less than 0.01 wt.%.

[0009] The preparation method of the Mg-Sr-In alloy anode material for magnesium-air batteries according to the present invention includes the following steps:

[0010] High-purity magnesium ingots, high-purity indium ingots, and magnesium-strontium master alloys are melted under a protective atmosphere, stirred and allowed to stand, surface slag is removed, and the mixture is refined at a constant temperature. After refining, the mixture is cast and cooled to obtain as-cast Mg-Sr-In anode material.

[0011] Furthermore, the melting temperature is 700℃~780℃.

[0012] Furthermore, the refining temperature is 720℃ and the refining time is 20 minutes.

[0013] Furthermore, the protective atmosphere is argon.

[0014] The magnesium-strontium-indium (Mg-Sr-In) alloy anode material for magnesium-air batteries of the present invention is used to prepare magnesium-air batteries and is suitable for use in any shape.

[0015] Furthermore, the magnesium-air battery device includes a Mg-Sr-In anode, an electrolyte, and a commercially available cathode.

[0016] This invention alters the microstructure of magnesium alloys by microalloying pure magnesium anodes with appropriate amounts of Sr and In elements. For as-cast Mg-Sr-In anode materials, Sr mainly exists in two forms: (1) the second phase Mg 17 Sr2 exists in the form of α-Mg matrix, with Mg strands. 17 Sr2 is distributed along the grain boundaries, and granular Mg 17 Sr2 is distributed within the crystal; (2) a small amount of strontium is dissolved in the α-Mg matrix in atomic form. During discharge, strontium can form an SrO-modified MgO / Mg(OH)2 film, enhancing corrosion resistance and making the discharge products easier to peel off. Mg 17 Sr2 can act as a weak cathode to accelerate the discharge dissolution of the surrounding α-Mg matrix and activate the anodic reaction kinetics.

[0017] Indium has a high solid solubility in magnesium matrix, and therefore exists mainly as dissolved atoms in the α-Mg matrix. During discharge, indium is oxidized to indium ions and released into the electrolyte. Subsequently, it is reduced to metallic indium by magnesium and strontium and deposited at the interface between the anode and the passivation film, thereby improving the interfacial conditions between the anode surface and the electrolyte. The indium deposition layer can maintain the anode activation area, accelerate the activation and dissolution of the magnesium-strontium-indium anode, and enhance its electrochemical activity. On the other hand, due to the high hydrogen evolution overpotential of indium, it can suppress the negative difference effect and reduce self-corrosion hydrogen evolution.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0019] The Mg-Sr-In alloy anode material of this invention can enhance the corrosion resistance of magnesium-air battery anodes, activate anode reaction kinetics, maintain anode activation area, suppress negative differential effects, and reduce self-corrosion hydrogen evolution. It can improve battery discharge voltage and anode efficiency while ensuring stable discharge, significantly extending battery life. Furthermore, the Mg-Sr-In anode material of this invention has a simple preparation process, low cost, and is easy to promote and apply, making it suitable for high-power electrical equipment. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings.

[0021] Figure 1 Metallographic optical microscope and electron microscope images of the as-cast Mg-Sr-In anode materials prepared in Examples 1 to 3 of the present invention, wherein (a) is Example 1, (b) is Example 2, and (c) is Example 3;

[0022] Figure 2 Examples 1-3 of the present invention are at 2mA cm -2 Electron microscope images of the anode surface after 10 hours of discharge at current density, where (a)(a1) is Example 1, (b)(b1) is Example 2, and (c)(c1) is Example 3;

[0023] Figure 3 Examples 1-3 of the present invention are at 40mA cm -2 Electron microscope images of the anode surface after 5 hours of discharge at current density, where (a)(a1) is Example 1, (b)(b1) is Example 2, and (c)(c1) is Example 3. Detailed Implementation

[0024] The technical solution provided by the present invention will be further described below with reference to the embodiments.

[0025] Example 1

[0026] A Mg-Sr-In alloy anode material for magnesium-air batteries is formulated with the following chemical composition by mass percentage: Sr 0.50 wt.%, In 0.42 wt.%, with the remainder being magnesium and unavoidable impurities.

[0027] Prepare a crucible, ensuring it is free from leaks and defects that could affect its use. Preheat the crucible to approximately 600°C, fill it with argon gas for protection, add high-purity magnesium ingots, high-purity indium ingots, and magnesium-strontium master alloy, and raise the heating temperature to 750°C to melt the raw materials into a molten state. After stirring, skim off any scum floating on the surface of the alloy liquid. Control the temperature at 720°C and hold the alloy liquid at that temperature for 20 minutes, then cast it into a cylindrical ingot.

[0028] Example 2

[0029] A Mg-Sr-In alloy anode material for magnesium-air batteries is formulated with the following chemical composition by mass percentage: Sr 0.47 wt.%, In 0.98 wt.%, with the remainder being magnesium and unavoidable impurities.

[0030] Prepare a crucible, ensuring it is free from leaks and defects that could affect its use. Preheat the crucible to approximately 600°C, fill it with argon gas for protection, add high-purity magnesium ingots, high-purity indium ingots, and magnesium-strontium master alloy, and raise the heating temperature to 750°C to melt the raw materials into a molten state. After stirring, skim off any scum floating on the surface of the alloy liquid. Control the temperature at 720°C and hold the alloy liquid at that temperature for 20 minutes, then cast it into a cylindrical ingot.

[0031] Example 3

[0032] A Mg-Sr-In alloy anode material for magnesium-air batteries is formulated with the following chemical composition by mass percentage: Sr 0.48 wt.%; In 1.76 wt.%, with the remainder being magnesium and unavoidable impurities.

[0033] Prepare a crucible, ensuring it is free from leaks and defects that could affect its use. Preheat the crucible to approximately 600°C, fill it with argon gas for protection, add high-purity magnesium ingots, high-purity indium ingots, and magnesium-strontium master alloy, and raise the heating temperature to 750°C to melt the raw materials into a molten state. After stirring, skim off any scum floating on the surface of the alloy liquid. Control the temperature at 720°C and hold the alloy liquid at that temperature for 20 minutes, then cast it into a cylindrical ingot.

[0034] Comparative Example 1

[0035] A Mg-Ca-Zn alloy anode material for magnesium-air batteries is formulated with the following chemical composition by mass percentage: Ca 1.02 wt.%; Zn 1.18 wt.%, with the remainder being magnesium and unavoidable impurities.

[0036] Prepare a crucible, ensuring it is free from leaks and defects that could affect its use. Preheat the crucible to approximately 600°C, fill it with argon gas for protection, add high-purity magnesium ingots, high-purity zinc ingots, and magnesium-calcium master alloy, and raise the heating temperature to 715°C to melt the raw materials into a molten state. After stirring, skim off any scum floating on the surface of the alloy liquid. After holding the liquid at this temperature for 20 minutes, pour it into a preheated graphite crucible at 200°C and cast it into a cylindrical ingot.

[0037] Comparative Example 2

[0038] A Mg-Ca-In alloy anode material for magnesium-air batteries is formulated with the following chemical composition by mass percentage: Ca ~ 1.54 wt.%; In ~ 3.36 wt.%; the remainder being magnesium and unavoidable impurities.

[0039] Prepare a crucible, ensuring it is free from leaks and defects that could affect its use. Fill the crucible with a mixture of CO2 and SF6 as a protective gas. Add high-purity magnesium ingots, high-purity indium ingots, and magnesium-calcium master alloy to the low-carbon steel crucible. Increase the heating temperature to 720°C to melt the raw materials into a molten state. After stirring, remove the slag from the surface of the alloy liquid and cool it to 690°C. Cast the liquid and water-cool it into a cylindrical ingot.

[0040] Comparative Example 3

[0041] A Mg-Ca-In alloy anode material for magnesium-air batteries is formulated with the following chemical composition by mass percentage: Ca 4.32 wt.%; In 3.76 wt.%, with the remainder being magnesium and unavoidable impurities.

[0042] Prepare a crucible, ensuring it is free from leaks and defects that would affect its use. Add high-purity magnesium ingots, high-purity indium ingots, and a magnesium-calcium master alloy to the low-carbon steel crucible. Increase the heating temperature to 720℃ to melt the raw materials in a vacuum. After stirring, skim off the slag from the surface of the alloy melt. Cool the mixture to 690℃ and cast it into a cylindrical ingot using water cooling. (Liu, H.;Zhao, G.;Li, H.;Tang, S.;Xiu, D.;Wang, J.;Yu, H.;Cheng, K.;Huang, Y.;Zhou, J. The Discharge Performance of Mg-3In-xCa Alloy Anodes for Mg-Air Batteries. Coatings 2022, 12, 428. https: / / doi.org / 10.3390 / coatings12040428)

[0043] Comparative Example 4

[0044] A Mg-Al-In alloy anode material for magnesium-air batteries is formulated with the following chemical composition by mass percentage: Al 6 wt.%; In 1 wt.%; the remainder being magnesium and unavoidable impurities.

[0045] Prepare a crucible free from leaks and other defects that could affect its use. Add high-purity magnesium ingots, high-purity indium ingots, high-purity aluminum ingots, and a magnesium-cerium master alloy to a low-carbon steel crucible. Increase the heating temperature to 720℃ to melt the raw materials in a vacuum. After stirring, skim off any slag from the surface of the molten alloy and pour it into a preheated crucible to form a cylindrical ingot. (Yaqiong Li, Jingling Ma, Guangxin Wang, Fengzhang Ren, Yujie Zhu, Yongfa Song, Jingli Zhang. Effect by adding Ce and In to Mg-6Al Alloy as anode on performance of Mg-airbatteries. Materials Research Express 2019, 6, 066315. https: / / doi.org / 10.1088 / 2053-1591 / ab0fb6)

[0046] Comparative Example 5

[0047] A Mg-Al-In-Ce alloy anode material for magnesium-air batteries is formulated with the following chemical composition by mass percentage: Al 6wt.%; In 1wt.%; Ce 1wt.%; with the remainder being magnesium and unavoidable impurities.

[0048] Prepare a crucible, ensuring it is free from leaks and defects that could affect its use. Fill the crucible with a mixture of CO2 and SF6 as a protective gas. Add high-purity magnesium ingots, high-purity indium ingots, high-purity aluminum ingots, and magnesium-cerium master alloy to the low-carbon steel crucible. Increase the heating temperature to 720°C to melt the raw materials into a molten state. After stirring, skim off the slag from the surface of the alloy liquid and pour it into the preheated crucible to form a cylindrical ingot.

[0049] The discharge current, average operating voltage, and anode efficiency of the anode materials in Examples 1-3 and Comparative Examples 1-5 are as follows:

[0050]

[0051]

[0052] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A Mg-Sr-In alloy anode material for magnesium-air batteries, characterized in that, The chemical composition by mass percentage is: Sr 0.1~2.0 wt.%, In 0.1~3.0 wt.%, balance Mg and unavoidable impurities.

2. The method for preparing the Mg-Sr-In alloy anode material for magnesium-air batteries according to claim 1, characterized in that, Includes the following steps: High-purity magnesium ingots, high-purity indium ingots, and magnesium-strontium master alloys are melted under a protective atmosphere, stirred and allowed to stand, surface slag is removed, and the mixture is refined at a constant temperature. After refining, the mixture is cast and cooled to obtain as-cast Mg-Sr-In anode material.

3. The preparation method according to claim 2, characterized in that, The melting temperature is 700℃~780℃.

4. The preparation method according to claim 2, characterized in that, The refining temperature is 720℃ and the refining time is 20 minutes.

5. The preparation method according to claim 2, characterized in that, The protective atmosphere is argon.

6. The application of the Mg-Sr-In alloy anode material according to claim 1 in the preparation of magnesium-air batteries.

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