Layered-structure Mg-Mn-based alloy with weak interlayer binding force as well as preparation method and application of layered-structure Mg-Mn-based alloy

Abstract

The invention discloses a layered structure Mg-Mn-based alloy with weak interlayer binding force and a preparation method and application thereof, the alloy material comprises a plurality of layers of Mg-Mn-based alloy plates, an oxide layer with a micro-nano structure is formed on the surface of each layer of Mg-Mn-based alloy plate, and microcracks are formed between the oxide layer and a matrix of the Mg-Mn-based alloy plate. The self-corrosion rate of the alloy material is low, and formation of a surface passivation film can be inhibited; and due to weak interlayer binding force and micro cracks between the oxide layer and the substrate, the discharge product can periodically fall off, and the stability of the discharge voltage is ensured.

Description

Technical Field

[0001] The invention relates to a layered Mg-Mn-based alloy with weak interlayer bonding force, a preparation method and application thereof, and belongs to the technical field of metal materials. Background Art

[0002] Metal-air batteries (MABs) are a promising new energy storage material that utilizes oxygen from the air as the cathode, thereby reducing the weight of the battery. Common types include lithium-air, zinc-air, magnesium-air, and aluminum-air batteries. Metal-air batteries have attracted considerable attention due to their high energy density, environmental friendliness, and low cost. Magnesium is abundant in the Earth's crust, relatively inexpensive, and has a theoretical capacity density second only to lithium and aluminum, making it an ideal lightweight electrode material. Magnesium is more readily preserved than lithium in the natural environment and is more readily activated in neutral solutions. MABs using magnesium and magnesium alloys as anode materials offer numerous advantages, including low cost, cleanliness, safety, high theoretical discharge voltage and energy density, and high electrochemical equivalence. As a potential green and clean energy source, they hold broad application prospects in portable electronic devices, marine underwater instruments, intelligent autonomous unmanned submarines, and backup energy sources.

[0003] In magnesium-air batteries, magnesium alloy anodes play a crucial role. Currently, magnesium-air battery anodes used in neutral electrolytes face the following main problems: First, the discharge voltage of magnesium-air batteries is low. This is because a passivation film easily forms on the surface of the magnesium alloy, covering the magnesium alloy matrix and reducing the discharge voltage of the magnesium-air battery. Furthermore, as the discharge process progresses, insoluble discharge products form on the surface of the magnesium anode, hindering direct contact between the new anode surface and the electrolyte, thereby reducing the discharge voltage of the magnesium-air battery. Second, the self-corrosion rate is high. Magnesium is chemically active, and the introduction of alloying elements and harmful impurities can lead to the appearance of a second phase. In the corrosive medium, the magnesium matrix easily forms a corrosion cell with the second phase, inducing galvanic corrosion. Furthermore, the uneven microstructure of the alloy also increases the self-corrosion rate of the anode. Summary of the Invention

[0004] The purpose of the present invention is to provide a layered Mg-Mn-based alloy with weak interlayer bonding, as well as its preparation method and application. The alloy material has a low self-corrosion rate and the ability to inhibit the formation of a surface passivation film. The weak interlayer bonding and microcracks between the oxide layer and the matrix can cause the discharge products to fall off periodically, ensuring the stability of the discharge voltage.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A layered Mg-Mn-based alloy material with weak interlayer bonding strength, comprising several layers of Mg-Mn-based alloy plates, each of which has a micro-nanostructured oxide layer formed on its surface, and microcracks formed between the oxide layer and the substrate of the Mg-Mn-based alloy plate; The alloy used in the Mg-Mn based alloy plate includes the following components in mass percentage: 1-2% Mn, 0.4-0.8% Li, 0.2-0.4% Sr, 0.1-0.3% Ca, and the balance is Mg.

[0006] The preparation method of the above-mentioned layered structure Mg-Mn based alloy material with weak interlayer bonding strength is to prepare the materials according to the alloy composition and content, then smelt to obtain alloy ingots, roll to obtain alloy substrates, and then perform laser etching, cumulative rolling treatment, and finally ultrasonic activation.

[0007] Preferably, the smelting conditions are: under a protective gas atmosphere, -40 to -30 kPa, 680-700° C., and 20-40 min.

[0008] Preferably, the specific rolling method is: firstly subjecting the alloy ingot to homogenization treatment at 350-450°C for 12-24 hours, and then hot rolling the homogenized alloy ingot at 250-350°C.

[0009] Preferably, the deformation of each rolling pass is controlled at 10-15%, the temperature is kept at 250-350°C for 10-20 minutes between each pass, the total deformation is controlled at 80-90%, and the thickness of the alloy substrate obtained by rolling is 2-3 mm.

[0010] Preferably, the conditions for laser etching are: a distance between the lens and the alloy substrate of 100-150 mm, a power of 30-50 W, and a scanning speed of 50-200 mm / s.

[0011] Preferably, the alloy substrate is polished and cleaned before laser etching.

[0012] Preferably, the cumulative rolling method is specifically as follows: cumulatively rolling at least two laser-etched alloy substrates at 150-250°C, with a single-pass deformation of 70-80%; then cutting the cumulatively rolled alloy substrates into multiple sheets of the same specification, and then cumulatively rolling the obtained sheets at 150-250°C, repeating 2-4 times, with a single-pass deformation of 70-80%.

[0013] Preferably, the ultrasonic activation method is: placing the layered structure alloy material obtained by cumulative rolling treatment in alcohol, and ultrasonically treating it at 1-3 kW for 20-40 minutes.

[0014] Application of the layered structure Mg-Mn-based alloy material with weak interlayer bonding force in a magnesium-air battery.

[0015] The beneficial effects of the present application are: The alloy is mainly added with Mn, the removal of impurities in the alloy smelting process is achieved by the Mn element, the impurity content in the alloy is significantly reduced, which is beneficial to reduce the self-corrosion rate of the alloy; trace amounts of Sr and Ca elements are added to the Mg-Mn-based alloy, which can not only reduce the self-corrosion rate of the alloy, but also avoid the formation of the second phase; the addition of a small amount of Li element promotes uniform corrosion of the alloy during discharging, inhibits the formation of a passivation film on the surface, and can maintain the stability of the discharge voltage of the magnesium-air battery. Laser etching on the surface of the plate can form an oxide layer with micro-nano structure on the surface of the plate, reducing the interlayer bonding force in the subsequent accumulative roll bonding process; through accumulative roll bonding of the alloy, the microstructure of the alloy can be significantly refined to obtain a ultra-fine grain structure, and the self-corrosion rate of the alloy can be reduced; through ultrasonic activation of the accumulative roll-bonded alloy, micro-cracks are further formed between the oxide layer and the alloy matrix, which is beneficial to the shedding of discharge products during discharging; the combination of laser etching, accumulative roll bonding and ultrasonic activation forms a layered structure with weak interlayer bonding force in the alloy, and each layer of alloy is easy to realize self-shedding of discharge products after discharging, so that fresh alloy is exposed to the electrolyte, ensuring the stability of the discharge voltage of the magnesium-air battery. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The metallographic photo of the alloy material prepared in Example 1; Figure 2 The transmission electron microscope photo of the alloy material prepared in Example 1; Figure 3 The atomic force microscope photo of the micro-nano structure obtained after laser etching in Example 1. DETAILED DESCRIPTION

[0017] Example 1: A preparation method of a Mg-Mn-based alloy material for an anode of a magnesium-air battery, comprising the following steps: (1) Alloy design: Mg-Mn-based alloy, comprising the following components in percentage by weight: 1% of Mn, 0.4% of Li, 0.2% of Sr, 0.1% of Ca, and the balance of Mg.

[0018] (2)Batching: according to the alloy composition design, the required weights of pure Mg, pure Li, Mg-Sr intermediate alloy and Mg-Ca intermediate alloy are calculated and weighed.

[0019] (3) Induction melting: Under the protection of argon atmosphere, heating and melting are carried out in a vacuum induction melting furnace (-40 kPa, 680 ° C, 20 min) to obtain Mg-Mn based alloy ingots.

[0020] (4) Homogenization treatment: The ingot was homogenized at 350°C for 12 h.

[0021] (5) Rolling: The ingot after homogenization treatment was hot rolled at 250 °C. The deformation of each rolling pass was controlled at 10%. The temperature was kept at 250 °C for 10 min between each pass. The total deformation was controlled at 80%. The thickness of the plate obtained by final rolling was 2 mm.

[0022] (6) Surface cleaning: Use sandpaper to polish the surface of the plate obtained by rolling, and use alcohol to clean the polished surface of the plate.

[0023] (7) Laser etching: In an atmospheric environment, a laser marking machine is used to perform laser etching on the plate surface. The laser etching conditions are: the distance between the lens and the alloy substrate is 100 mm, the power is 30 W, and the scanning speed is 50 mm / s.

[0024] (8) Four-layer cumulative rolling: Four laser-etched plates are cumulatively rolled at a cumulative rolling temperature of 150°C and a cumulative rolling deformation of 75% per single pass.

[0025] (9) Multi-pass cumulative rolling: After the four-layer cumulative rolling, the plate is cut into four equal pieces and then the above four-layer cumulative rolling operation is repeated for a total of 2 passes.

[0026] (10) The alloy after cumulative rolling was placed in alcohol and activated in an ultrasonic cleaning device for 20 minutes with an ultrasonic power of 1 kW.

[0027] The metallographic photographs and transmission electron microscope photographs of the alloy material prepared in Example 1 are respectively Figure 1 、 2 As shown, it can be seen that the Mg-Mn based alloy material forms a layered structure with an interlayer spacing of about 125 μm, and ultrafine grains with a diameter of about 550 nm are formed in the layer.

[0028] The battery test system mainly includes anode alloy, air cathode, battery housing, electrolyte and battery test system. Among them, the anode is the alloy material prepared above, and the air cathode is a commercial nickel mesh cathode with MnO2 / C as the catalytic layer. In a standard neutral salt solution (3.5% NaCl), at 10mA / cm 2 At a current density of , after a 5-hour discharge test, the voltage stabilized in the range of 1.52±0.08V; after a 20-hour long-term discharge, the voltage fluctuation range remained in the range of 1.48±0.16V.

[0029] Example 2: A method for preparing a Mg-Mn-based alloy material for a magnesium-air battery anode, comprising the following steps: (1) Alloy design: Mg-Mn based alloy containing the following components in weight percentage: 2% Mn, 0.8% Li, 0.4% Sr, 0.3% Ca, and the balance Mg.

[0030] (2) Ingredients: According to the alloy composition design, calculate and weigh the weight of the required pure Mg, pure Li, Mg-Sr master alloy and Mg-Ca master alloy.

[0031] (3) Induction melting: Under the protection of argon atmosphere, heating and melting are carried out in a vacuum induction melting furnace (-30 kPa, 700 ° C, 40 min) to obtain Mg-Mn based alloy ingots.

[0032] (4) Homogenization treatment: The ingot was homogenized at 450°C for 24 h.

[0033] (5) Rolling: The ingot after homogenization treatment was hot rolled at 350 °C. The deformation of each rolling pass was controlled at 15%. The temperature was kept at 350 °C for 20 min between each pass. The total deformation was controlled at 90%. The thickness of the plate obtained by final rolling was 3 mm.

[0034] (6) Surface cleaning: Use sandpaper to polish the surface of the rolled plate, and use alcohol to clean the polished surface of the plate.

[0035] (7) Laser etching: In an atmospheric environment, a laser marking machine is used to perform laser etching on the surface of the plate. The laser etching conditions are: the distance between the lens and the alloy substrate is 150 mm, the power is 50 W, and the scanning speed is 200 mm / s. The atomic force microscope photo of the micro-nano structure obtained after laser etching is shown in Figure 2. Figure 3 shown.

[0036] (8) Four-layer cumulative rolling: Four laser-etched plates are cumulatively rolled at a cumulative rolling temperature of 250°C and a single-pass deformation of 75%.

[0037] (9) Multi-pass cumulative rolling: After the four-layer cumulative rolling, the plate is cut into four equal pieces and then the above four-layer cumulative rolling operation is repeated again, for a total of 4 passes.

[0038] (10) The alloy after cumulative rolling was placed in alcohol and activated in a high-power ultrasonic cleaning device for 40 minutes with an ultrasonic power of 3 kW.

[0039] The prepared Mg-Mn based alloy forms a layered structure with an interlayer spacing of about 12 μm and ultrafine grains with a diameter of about 320 nm formed in the layer. The battery test system mainly includes an anode alloy, an air cathode, a battery shell, an electrolyte and a battery test system. Among them, the anode is the alloy material prepared above, and the air cathode is a commercial nickel mesh cathode with MnO2 / C as the catalytic layer. In a standard neutral salt solution (3.5% NaCl), at 10 mA / cm 2 At a current density of , after a 5-hour discharge test, the voltage stabilized in the range of 1.56±0.06V; after a 20-hour long-term discharge, the voltage fluctuation range remained in the range of 1.51±0.19V.

[0040] Example 3: A method for preparing a Mg-Mn based alloy material for a magnesium air battery anode, comprising the following steps: (1) Alloy design: Mg-Mn based alloy containing the following components in weight percentage: 1.5% Mn, 0.6% Li, 0.3% Sr, 0.2% Ca, and the balance Mg.

[0041] (2) Ingredients: According to the alloy composition design, calculate and weigh the weight of the required pure Mg, pure Li, Mg-Sr master alloy and Mg-Ca master alloy.

[0042] (3) Induction melting: Under the protection of argon atmosphere, heating and melting are carried out in a vacuum induction melting furnace (-35 kPa, 690 ° C, 35 min) to obtain Mg-Mn based alloy ingots.

[0043] (4) Homogenization treatment: The ingot was homogenized at 400°C for 18 h.

[0044] (5) Rolling: The ingot after homogenization treatment was hot rolled at 300 °C. The deformation of each rolling pass was controlled at 12%. The temperature was kept at 300 °C for 15 min between each pass. The total deformation was controlled at 85%. The thickness of the plate obtained by final rolling was 2.5 mm.

[0045] (6) Surface cleaning: Use sandpaper to polish the surface of the rolled plate, and use alcohol to clean the polished surface of the plate.

[0046] (7) Laser etching: In an atmospheric environment, a laser marking machine is used to perform laser etching on the plate surface. The laser etching conditions are: the distance between the lens and the alloy substrate is 100 mm, the power is 40 W, and the scanning speed is 100 mm / s.

[0047] (8) Four-layer cumulative rolling: Four laser-etched plates are cumulatively rolled at a cumulative rolling temperature of 200°C and a single-pass deformation of 75%.

[0048] (9) Multi-pass cumulative rolling: After the four-layer cumulative rolling, the plate is cut into four equal pieces and then the above four-layer cumulative rolling operation is repeated for a total of 3 times.

[0049] (10) The alloy after cumulative rolling was placed in alcohol and activated in a high-power ultrasonic cleaning device for 30 minutes with an ultrasonic power of 2 kW.

[0050] The prepared Mg-Mn based alloy forms a layered structure with an interlayer spacing of about 40 μm and ultrafine grains with a diameter of about 430 nm formed in the layer. The battery test system mainly includes an anode alloy, an air cathode, a battery shell, an electrolyte and a battery test system. Among them, the anode is the alloy material prepared above, and the air cathode is a commercial nickel mesh cathode with MnO2 / C as the catalytic layer. In a standard neutral salt solution (3.5% NaCl), at 10 mA / cm 2 At a current density of , after a 5-hour discharge test, the voltage stabilized in the range of 1.58±0.09V; after a 20-hour long-term discharge, the voltage fluctuation range remained in the range of 1.52±0.18V.

[0051] The above is only a preferred embodiment of the patent of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the patent of the present invention. These improvements and modifications should also be regarded as the scope of protection of the patent of the present invention.

Claims

1. A layered Mg-Mn based alloy material with weak interlayer bonding strength, characterized in that: The invention comprises several layers of Mg-Mn-based alloy plates, each of which has an oxide layer with a micro-nano structure formed on the surface of the Mg-Mn-based alloy plate, and micro cracks are formed between the oxide layer and the substrate of the Mg-Mn-based alloy plate; The alloy used in the Mg-Mn based alloy plate includes the following components in mass percentage: 1-2% Mn, 0.4-0.8% Li, 0.2-0.4% Sr, 0.1-0.3% Ca, and the balance is Mg.

2. The method for preparing the layered Mg-Mn based alloy material with weak interlayer bonding according to claim 1, characterized in that: The alloy ingot is obtained by smelting after the ingredients are prepared according to the alloy composition and content, and the alloy substrate is obtained by rolling, which is then subjected to laser etching, cumulative rolling treatment, and finally ultrasonic activation.

3. The method for preparing a layered Mg-Mn based alloy material with weak interlayer bonding according to claim 2, characterized in that: The smelting conditions are: under protective gas atmosphere, -40~-30kPa, 680-700℃, 20-40min.

4. The method for preparing a layered Mg-Mn based alloy material with weak interlayer bonding according to claim 2, characterized in that: The specific rolling method is: firstly subjecting the alloy ingot to homogenization treatment at 350-450°C for 12-24 hours, and then hot rolling the homogenized alloy ingot at 250-350°C.

5. The method for preparing a layered Mg-Mn based alloy material with weak interlayer bonding according to claim 4, characterized in that: The deformation of each rolling pass is controlled at 10-15%, and the temperature is kept at 250-350℃ for 10-20 minutes between each pass. The total deformation is controlled at 80-90%, and the thickness of the alloy substrate obtained by rolling is 2-3mm.

6. The method for preparing a layered Mg-Mn based alloy material with weak interlayer bonding according to claim 2, characterized in that: The conditions for laser etching are: the distance between the lens and the alloy substrate is 100-150 mm, the power is 30-50 W, and the scanning speed is 50-200 mm / s.

7. The method for preparing a layered Mg-Mn based alloy material with weak interlayer bonding according to claim 2, characterized in that: Before laser etching, the alloy substrate was polished and cleaned.

8. The method for preparing a layered Mg-Mn based alloy material with weak interlayer bonding according to claim 2, characterized in that: The specific method of cumulative rolling is: cumulatively rolling at least two laser-etched alloy substrates at 150-250°C, with a single-pass deformation of 70-80%; then cutting the cumulatively rolled alloy substrates into multiple sheets of the same specification, and then cumulatively rolling the obtained sheets at 150-250°C, repeating 2-4 times, with a single-pass deformation of 70-80%.

9. The method for preparing a layered Mg-Mn based alloy material with weak interlayer bonding according to claim 2, characterized in that: The ultrasonic activation method is as follows: placing the layered structure alloy material obtained by cumulative rolling treatment in alcohol, and ultrasonically treating it at 1-3kW for 20-40 minutes.

10. Use of the layered Mg-Mn based alloy material with weak interlayer bonding force according to claim 1 in magnesium-air batteries.

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