Micro-alloyed magnesium alloy negative electrode material and preparation method and application thereof

Abstract

The present application relates to the technical field of magnesium secondary battery electrode material, and particularly relates to a micro-alloyed magnesium alloy negative electrode material and a preparation method and application thereof, which comprises the following components in percentage by mass: 0.01~2.0wt.% of Gd and / or 0.01~2.0wt.% of Ce, 0.01~1.0wt.% of Mn, and the balance of Mg. The preparation method comprises the following steps: weighing raw materials according to the component proportion of the micro-alloyed magnesium alloy negative electrode material, melting and pouring the raw materials, and obtaining an ingot by air cooling and solidification; the raw materials comprise pure Mg, Mg-Gd intermediate alloy and Mg-Mn intermediate alloy, or the raw materials comprise pure Mg, Mg-Ce intermediate alloy and Mg-Mn intermediate alloy; and the ingot is sequentially subjected to solid solution treatment, extrusion treatment, rolling treatment and annealing treatment to obtain the micro-alloyed magnesium alloy negative electrode material. The micro-alloyed magnesium alloy negative electrode material has excellent long cycle stability, low overpotential, is friendly to the environment and low in cost.

Description

Technical Field

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

[0002] Lithium-ion batteries, due to their high cost and poor safety, are gradually failing to meet the growing societal demands. Rechargeable magnesium batteries, as a promising new type of battery, possess a high theoretical volumetric capacity (3833 mAh / cm³). 3 Its advantages, such as abundant resources (approximately 104 times that of lithium in the Earth's crust), low reduction potential (-2.37V), and resistance to dendrite growth, have attracted widespread attention.

[0003] Ideal anode materials require very high specific capacity and low reaction voltage, and magnesium is a relatively ideal anode material. Magnesium was initially thought to be dendrite-free when used as an anode in secondary batteries, but this conclusion is highly dependent on the electrolyte and current density. Recent studies have shown that dendrites can grow on the surface of magnesium under fast charging or certain low-temperature conditions, and their hardness can even exceed that of lithium dendrites. Furthermore, in conventional electrolytes, a dense passivation film forms on the surface of magnesium, hindering the growth of Mg. 2+ The migration of magnesium leads to problems such as voltage hysteresis. Due to the presence of the passivation film, bulk magnesium metal is not suitable for some polar electrolytes. Therefore, in addition to improving the magnesium electrolyte, efforts should also be made to improve the compatibility between the magnesium anode and the electrolyte.

[0004] Currently, domestic and foreign researchers mainly focus on positive electrode materials and electrolytes in their research on magnesium-ion batteries. Pure magnesium is generally used as the negative electrode material. There are few research reports on other negative electrode materials, especially binary alloys for rechargeable magnesium batteries. Furthermore, the various rechargeable magnesium battery alternatives currently being researched are limited in large-scale production and application due to their complex manufacturing processes and high costs. Summary of the Invention

[0005] The purpose of this invention is to provide a microalloyed magnesium alloy anode material, its preparation method and application, which has excellent long-cycle stability, low overpotential, is environmentally friendly and low cost.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a microalloyed magnesium alloy anode material comprising, by mass percentage: 0.01 to 2.0 wt.% Gd and / or 0.01 to 2.0 wt.% Ce, 0.01 to 1.0 wt.% Mn, with the balance being Mg.

[0008] Furthermore, the content of impurity elements in the microalloyed magnesium alloy anode material is <0.05 wt.%.

[0009] Secondly, this invention provides a method for preparing a microalloyed magnesium alloy anode material, comprising:

[0010] Raw materials are weighed according to the above-mentioned composition ratio of microalloyed magnesium alloy anode material, the raw materials are melted, cast, and air-cooled to obtain ingots; the raw materials include pure Mg, Mg-Gd master alloy and Mg-Mn master alloy, or the raw materials include pure Mg, Mg-Ce master alloy and Mg-Mn master alloy.

[0011] The ingot was subjected to solution treatment, extrusion treatment, rolling treatment and annealing treatment in sequence to obtain microalloyed magnesium alloy anode material.

[0012] Further, the process of melting, casting, and air-cooling solidification of raw materials to obtain ingots specifically includes: surface cleaning of raw materials; preheating a crucible to 300-500°C in a melting furnace, adding pure Mg to the crucible under a mixed protective atmosphere of CO2 and SF6, and continuing to raise the temperature to 650-700°C; after all the pure Mg has melted, raising the temperature to 740-760°C, adding preheated Mg-Gd and Mg-Mn master alloys or Mg-Ce and Mg-Mn master alloys, skimming off slag, and stirring until the master alloys are completely melted; stopping heating and holding at the temperature for 20-30 minutes, skimming off slag, adding refining agents, and stirring until the surface of the molten metal becomes mirror-like to obtain a melt; allowing the melt to stand at 740-760°C for 20-30 minutes, skimming off slag, and then pouring the melt into a mold and air-cooling solidification to obtain an ingot.

[0013] Furthermore, the inner wall of the crucible, the inner surface of the mold, and the parts of the skimming tool and stirring tool that come into contact with the molten metal are uniformly coated with boron nitride paint, and the crucible, mold, skimming tool and stirring tool are preheated and dried at a temperature of 200℃~300℃.

[0014] Furthermore, the solution treatment specifically includes: covering the ingot with aluminum foil, placing the ingot in a stainless steel crucible, covering it with graphite powder to prevent oxidation, and then performing solution treatment in a heating furnace; the solution treatment temperature is set to 300~400℃, the solution treatment time is set to 8~24h, and the cooling method is water cooling.

[0015] Furthermore, the extrusion process specifically includes: machining the solution-treated ingot into an extrusion billet, and then extruding it at a temperature of 350~450℃.

[0016] Furthermore, the rolling process specifically includes: holding the extruded slab obtained from the extrusion process at a temperature of 250~300℃ for 10~30 minutes, and then rolling it; the rolling passes are 3~5 times, the reduction of the sheet material in each pass is set to 20~30%, and after each rolling pass, it is held at a temperature of 250~300℃ for 10~30 minutes.

[0017] Furthermore, the annealing temperature for the annealing treatment is set to 300~400℃, and the annealing time is set to 10~30min.

[0018] Thirdly, the present invention provides an application of the above-mentioned microalloyed magnesium alloy anode material in the anode of a magnesium battery.

[0019] The present invention has the following unexpected beneficial effects:

[0020] 1. This invention addresses the short cycle life drawback of pure magnesium anodes by preparing a microalloyed ternary magnesium alloy for magnesium secondary battery anode materials through melting, solution treatment, extrusion, rolling, and annealing of high-purity Mg, Mn, Gd, and / or Ce in a specific mass ratio. Compared to pure magnesium, this microalloyed magnesium alloy exhibits lower polarization overpotentials at different current densities and superior dissolution / deposition stability during cycling. Furthermore, the microalloyed magnesium alloy anode material effectively suppresses dendrite formation at the interface, resulting in a longer cycle life even at higher current densities.

[0021] 2. The preparation method described in this invention is simple, and the addition of trace alloying elements not only improves the electrochemical performance of pure magnesium but also gives the magnesium alloy anode material superior processing performance. At the same time, it has low cost, can be applied to large-scale industrial production, and has better application prospects.

[0022] 3. The main raw material described in this invention, magnesium, is abundant and readily available. Furthermore, the amount of added elements is small, resulting in minimal impact on the ecological environment and avoiding heavy reliance on scarce resources. The excellent electrochemical performance of the alloy significantly improves the cycle life of the battery, reducing resource waste and the environmental burden of discarded batteries caused by frequent replacements. Simultaneously, its preparation and use do not involve highly toxic chemicals, ensuring high safety and avoiding the thermal runaway risk and environmental pollution associated with lithium-ion batteries. Moreover, magnesium alloys are easy to recycle, and their degradation process is harmless to the ecosystem, contributing to the popularization of green energy storage and the development of a circular economy. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the preparation method of the microalloyed magnesium alloy anode material described in this invention;

[0024] Figure 2 The current density is 0.3 mA·cm. -2-0.3mAh·cm -2 Charge-discharge curves of pure magnesium, Mg-Mn, Mg-Gd and Mg-Gd-Mn symmetric cells under the condition of 0.4 M APC electrolyte system;

[0025] Figure 3 The current density is 0.3 mA·cm. -2 -0.3mAh·cm -2 Voltage relaxation plots of pure magnesium, Mg-Mn, Mg-Gd and Mg-Gd-Mn symmetric cells in a 0.4 M APC electrolyte system under the given conditions;

[0026] Figure 4 The current density is 3 mA·cm -2 -3mAh·cm -2 Charge-discharge curves of pure magnesium, Mg-Mn, Mg-Gd and Mg-Gd-Mn symmetric cells under the condition of 0.4 M APC electrolyte system;

[0027] Figure 5 The current density is 0.3 mA·cm. -2 -0.3mAh·cm -2 A schematic diagram comparing the coulombic efficiencies of pure magnesium, Mg-Mn, Mg-Gd, and Mg-Gd-Mn half-cells after 200 cycles in an APC electrolyte system with a concentration of 0.4 M.

[0028] Figure 6 The current density is 3 mA·cm -2 -3mAh·cm -2 Charge-discharge curves of pure magnesium, Mg-Mn, Mg-Ce, and Mg-Ce-Mn symmetric cells under the condition of 0.4 M APC electrolyte system.

[0029] Figure 7 The current density is 3 mA·cm -2 -5mAh·cm -2 Charge-discharge curves of pure magnesium, Mg-Mn, Mg-Ce and Mg-Ce-Mn symmetric cells under the condition of 0.4 M APC electrolyte system in the first 20 h. Detailed Implementation

[0030] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0031] In one embodiment, the present invention provides a microalloyed magnesium alloy anode material comprising, by mass percentage: 0.01-2.0 wt.% Gd and / or 0.01-2.0 wt.% Ce, 0.01-1.0 wt.% Mn, with the balance being Mg.

[0032] This invention, through the rational selection of alloying elements and optimization of alloy composition, achieves a lower polarization overpotential and superior dissolution and deposition stability during cycling compared to pure magnesium at different current densities. Compared to lithium metal anodes, magnesium metal anodes are less prone to dendrite formation during electrodeposition, and microalloying further suppresses magnesium dendrite growth, resulting in a longer cycle life even at higher current densities. This avoids the problem of dendrites penetrating the separator and causing short circuits, thus improving battery safety and cycle stability. Furthermore, the addition of trace alloying elements (Mn, Gd, and / or Ce) refines the magnesium alloy grains, enhancing its matrix strength and hardness. This allows the anode material to better maintain the integrity of the electrode structure during charging and discharging, reducing electrode material pulverization and detachment, thereby improving battery cycle life and stability.

[0033] In a preferred embodiment, the content of impurity elements in the microalloyed magnesium alloy anode material is <0.05wt%. By reducing the content of impurity elements, the occurrence of adverse side reactions can be reduced, thereby improving the electrochemical performance of the battery, such as increasing energy density, extending cycle life, and enhancing stability.

[0034] Reducing impurity elements helps maintain the uniformity and integrity of materials, thereby improving their mechanical properties, such as enhancing toughness, reducing brittleness, and improving fatigue resistance.

[0035] Strict control of impurity elements can also reduce defects and malfunctions that may occur during material processing and use, thereby improving the reliability and safety of products.

[0036] The following methods can be used to control the content of impurity elements.

[0037] 1) Raw material selection: Selecting high-purity raw materials is key to reducing the content of impurity elements. This includes ensuring that the raw materials for magnesium, rare earth elements, and transition metal elements are of high purity, and avoiding the use of recycled materials containing a large number of impurities.

[0038] 2) Production process optimization: During the smelting and casting process, take appropriate measures to reduce the introduction of impurities, such as using inert gas protection, controlling smelting temperature and time, and adopting effective impurity removal processes.

[0039] 3) Quality inspection and monitoring: Strict quality inspection and monitoring are carried out at each stage of the production process to ensure that the impurity element content of the final product meets the specified requirements.

[0040] In one embodiment, the present invention provides a method for preparing a microalloyed magnesium alloy anode material, see [link to relevant documentation]. Figure 1 As shown, the preparation method includes:

[0041] Raw materials are weighed according to the component ratio of the microalloyed magnesium alloy anode material described in the above embodiments, and the raw materials are melted, cast, and air-cooled to obtain an ingot; the raw materials include pure Mg, Mg-Gd master alloy and Mg-Mn master alloy, or the raw materials include pure Mg, Mg-Ce master alloy and Mg-Mn master alloy.

[0042] The ingot was subjected to solution treatment, extrusion treatment, rolling treatment and annealing treatment in sequence to obtain microalloyed magnesium alloy anode material.

[0043] The preparation method described in this invention has the advantages of simple process, easy control, and low cost, and is suitable for large-scale industrial production, with good application prospects.

[0044] In a preferred embodiment, the process of melting, casting, and air-cooling solidification of raw materials to obtain an ingot specifically includes:

[0045] The raw materials undergo surface cleaning to prevent impurities from entering the melt during smelting and affecting the properties of the final material. Specific methods include mechanical grinding, acid washing, and alkali washing.

[0046] Preheat the crucible in the melting furnace to 300-500℃. Preheating the crucible reduces heat absorption by the melt during melting and prevents it from cracking due to rapid temperature increases. Under a protective atmosphere of CO2 and SF6, add pure Mg to the crucible and continue heating to 650-700℃. After all the pure Mg has melted, raise the temperature to 740-760℃ and add preheated Mg-Gd and Mg-Mn master alloys or Mg-Ce and Mg-Mn master alloys. Skim off any slag and stir until the master alloys are completely melted.

[0047] Stop heating and hold at that temperature for 20-30 minutes to allow the melt composition to become more homogeneous. Skim off the slag again, then add the refining agent. The refining agent removes gases and fine impurities from the melt, improving its purity. Stir until the surface of the molten metal becomes mirror-like, indicating that the melt has been sufficiently refined. Let the melt stand at 740-760℃ for 20-30 minutes to allow impurities and gases to rise and separate further.

[0048] The melt is allowed to stand for 20-30 minutes at a temperature of 740-760℃, slag is skimmed off, and then the melt is poured into a mold for air cooling and solidification to obtain an ingot. Air cooling and solidification is relatively slow, which is beneficial for a more uniform composition and structure in the ingot.

[0049] Furthermore, the inner wall of the crucible, the inner surface of the mold, and the parts of the skimming tool and stirring tool that come into contact with the molten metal are uniformly coated with boron nitride paint, and the crucible, mold, skimming tool and stirring tool are preheated and dried at a temperature of 200℃~300℃.

[0050] Boron nitride (BN) coatings possess excellent high-temperature resistance, corrosion resistance, and lubrication properties. When applied to the inner walls of crucibles, the inner surfaces of molds, and areas where skimming tools, stirring tools, and molten metal come into contact with the molten metal, they effectively prevent these areas from being corroded or adhered to by the molten metal at high temperatures. Simultaneously, they reduce friction between the molten metal and these areas, improving the smoothness of the melting and casting process.

[0051] Application Method: Ensure the paint is applied evenly to the surfaces of these areas to form a continuous, dense coating. Before application, clean the surfaces to remove oil, impurities, etc., to ensure good adhesion between the paint and the substrate.

[0052] Preheating and drying crucibles, molds, skimming tools, and stirring tools at 200℃~300℃ removes moisture and adsorbed gases from their surfaces, preventing quality problems such as splashing and porosity caused by moisture evaporation or gas release during smelting and casting. Preheating also reduces the temperature difference between these tools and the high-temperature molten metal, preventing thermal stress cracks caused by rapid temperature increases.

[0053] Preheating method: Place the crucible, mold, skimming tools, and stirring tools into a preheating furnace, heat to the specified temperature, and maintain this temperature for a period of time to ensure uniform temperature both inside and outside the tools. The preheating time should be adjusted according to the size and material of the tools.

[0054] In a preferred embodiment, the solution treatment specifically includes:

[0055] Aluminum foil cladding: First, the ingot is clad with aluminum foil. Aluminum foil has excellent sealing and corrosion resistance, effectively preventing the ingot from direct contact with oxygen in the air during solution treatment, thus avoiding oxidation. At the same time, the aluminum foil also acts as a buffer layer, reducing thermal stress on the ingot during heating and cooling.

[0056] Placement of the stainless steel crucible: Place the coated ingot in the stainless steel crucible. The stainless steel crucible has good high-temperature resistance and chemical stability, and can withstand the high-temperature environment during the solution treatment process, while preventing the ingot from reacting with the crucible material.

[0057] Graphite powder coating: A layer of graphite powder is applied over the ingot. Graphite powder has good thermal conductivity and chemical inertness, further preventing oxidation of the ingot during solution treatment, while also helping to evenly transfer heat and improve the efficiency of solution treatment.

[0058] Solution treatment in a heating furnace: A stainless steel crucible containing the ingot is placed in a heating furnace for solution treatment. The solution treatment temperature is set at 300~400℃, and the solution treatment time is set at 8~24 hours. This combination of temperature and time is to ensure that the alloying elements are fully dissolved in the magnesium matrix to form a homogeneous solid solution, thereby improving the material's properties.

[0059] Water cooling: After solution treatment, the ingot is rapidly cooled using water cooling. Water cooling can quickly lower the temperature of the ingot, preventing alloying elements from re-precipitating during the cooling process, thus maintaining the homogeneity of the solid solution. At the same time, water cooling can also reduce thermal stress on the ingot during the cooling process, avoiding defects such as cracks.

[0060] In a preferred embodiment, the extrusion process specifically includes: machining the solution-treated ingot into an extrusion billet to remove surface defects such as oxide scale and inclusions, and adjusting its shape and size to meet the requirements of the extruder. During the processing, it is necessary to ensure the dimensional accuracy and surface quality of the billet to avoid defects such as cracks and folds during extrusion.

[0061] Then, extrusion is carried out at a temperature of 350~450℃. This temperature is determined based on the extrusion characteristics and required properties of the magnesium alloy, aiming to ensure that the alloy has good plasticity and fluidity during extrusion, while avoiding overheating that leads to coarsening of the microstructure and degradation of properties.

[0062] In a preferred embodiment, the rolling process specifically includes: holding the extruded slab obtained from the extrusion process at a temperature of 250-300°C for 10-30 minutes to ensure uniform internal temperature of the slab, reduce thermal stress during rolling, and improve the plasticity and fluidity of the material, which is beneficial for subsequent rolling operations. Then, rolling is performed in 3-5 passes, with a reduction of 20-30% per pass. A reasonable reduction helps to obtain a uniform microstructure and good mechanical properties. After each rolling pass, the slab is held at 250-300°C for 10-30 minutes. This heating and holding process releases internal stress in the slab and restores the material's plasticity, preparing it for the next rolling pass.

[0063] In a preferred embodiment, the annealing temperature for the annealing treatment is set to 300~400°C. At this temperature, the residual stress in the magnesium alloy can be effectively released, while avoiding grain growth and performance degradation caused by excessively high temperatures.

[0064] The annealing time is set to 10-30 minutes, and the length of the annealing time directly affects the microstructure and properties of the material. If the annealing time is too short, the residual stress may not be fully released, affecting the material's properties; if the annealing time is too long, it may lead to grain growth, reducing the material's strength and hardness.

[0065] In one embodiment, the present invention provides an application of the microalloyed magnesium alloy anode material described in any of the above embodiments in the anode of a magnesium battery.

[0066] The present invention will be analyzed and explained below with specific examples.

[0067] Example 1: A method for preparing a microalloyed magnesium alloy anode material, comprising the following steps:

[0068] Step 1: Preparation of magnesium alloy ingots

[0069] Under the protection of a mixed gas of CO2 and SF6, pure magnesium ingots and intermediate alloys are melted in sequence according to the proportion to obtain an alloy melt. The melt is then skimmed off and a refining agent is added. Finally, the melt is cast under a protective atmosphere to obtain the as-cast alloy.

[0070] Specifically, the following steps are included:

[0071] A. Preparation of furnace charge and equipment: Use an electric polisher to remove oxides from the surface of pure magnesium ingots (99.99 wt.%) and intermediate alloys (Mg-30 wt.% Gd, Mg-5 wt.% Mn), ensuring the furnace charge is free of mold, rust, oil, etc., and then cut it into small pieces for later use. Coat the surfaces of stirring tools, casting molds, crucibles, and other surfaces that come into contact with the melt with a coating made of boron nitride and alcohol in a volume ratio of 1:4, and preheat it at a temperature of 200~300℃ for at least 30 minutes.

[0072] B. Batching: Considering that the burn-off of the added trace amount of Gd is 10%~15% and the burn-off of Mn is about 25%, and about 3kg of alloy is melted each time, the amount of intermediate alloy required to melt the Mg-Gd-Mn alloy is shown in Table 1.

[0073] Table 1. Required amount of intermediate alloy for smelting Mg-1.0Gd-0.3Mn alloy

[0074]

[0075] C. Melting: Preheat the crucible to a dark red color (approximately 500°C), add a fixed amount of pure magnesium ingots, and introduce a mixed protective gas of CO2 and SF6, wherein the volume ratio of the mixed protective gas of CO2 and SF6 is: Continue heating to melt the magnesium ingot; raise the temperature to 650℃ until all the magnesium ingot has melted. Then raise the temperature to 740℃, add a preheated, measured amount of intermediate alloy, skim off any slag, and stir for 2-3 minutes until completely melted, promoting the dissolution and dispersion of alloying elements. Add other alloys in the same manner (in the order of Mg-30Gd, Mg-5Mn), ensuring a continuous supply of protective gas and a complete shutdown of the heating power each time a raw material is added. Once the metal has melted, skim off any surface slag, add JDMJ refining agent, and refine for 3-5 minutes while stirring.

[0076] D. Casting: The melt is allowed to stand for 20 minutes at a temperature of 740℃ before casting. Before casting, slag is removed to remove oxides from the surface of the melt. The melt is then poured into a preheated (200~300℃) cast iron mold. Finally, it is air-cooled, demolded, and sampled to obtain the Mg-1.0Gd-0.3Mn alloy ingot.

[0077] Step 2, Solution Treatment: Solution treatment is performed using a heat treatment furnace. The furnace is heated to 400℃, and the alloy ingot is placed in the furnace and held at that temperature for 24 hours. After that, it is removed and water-cooled to obtain a solution-treated magnesium alloy ingot. That is, the heat treatment parameters for solution treatment are 400℃ × 24h, followed by water cooling.

[0078] Step 3, preparation of extruded slab: The solution-treated magnesium alloy ingot is surface-treated by grinding off the surface oxide film, and the solution-treated magnesium alloy ingot is preheated in a heat-preserving environment at 400°C for 30 minutes. During the extrusion process, the temperature is 400°C and the extrusion ratio is 47:1, finally obtaining a Mg-1.0Gd-0.3Mn magnesium alloy slab with a thickness of 2mm.

[0079] Step 4, Preparation of rolled sheet: The cross-sectional dimensions of the extruded slab used for rolling are 60mm×2mm. Rolling is carried out at a temperature of 250℃. Before rolling, the slab is kept in a 250℃ heat preservation environment for 30 minutes.

[0080] After each rolling pass, the plate is held at 250℃ for 10 minutes. The reduction per pass is kept constant at 30%. A total of three rolling passes are performed, and the final Mg-1.0Gd-0.3Mn plate has a thickness of approximately 0.7 mm.

[0081] Step 5, Electrode preparation: A magnesium alloy sheet with a thickness of approximately 0.7 mm is annealed at 400°C for 10 minutes. After annealing, it is cut into 14 mm diameter magnesium alloy negative electrode sheets using a slicing machine. The sheets are then sanded to 3000 grit to remove the oxide layer, resulting in a thickness of 0.3-0.5 mm. Next, the sheets are ultrasonically cleaned in alcohol for 10 minutes, dried in a vacuum oven for 12 hours, and then stored in an argon glove box with an oxygen content of less than 1 ppm for later use.

[0082] Electrochemical Analysis: CR2032 coin cells were assembled in an argon-filled glove box using the prepared magnesium alloy as electrodes, GF / A glass fiber as separator, and 0.4M APC as electrolyte. The assembly sequence for symmetrical cells was: negative electrode shell, alloy negative electrode sheet, separator, alloy negative electrode sheet, gasket, spring sheet, and positive electrode shell. For half-cell assembly, one side of the positive electrode shell was replaced with Φ12mm copper foil, while the rest remained unchanged. All battery shells, copper foil, gaskets, and spring sheets were ultrasonically cleaned twice in deionized water for 20 minutes each time, followed by drying in a forced-air drying oven. The separator diameter was Φ17mm, and 100μL of electrolyte was used each time. After assembly, the batteries were compacted on an automatic sealing machine and allowed to stand for 12 hours to ensure complete electrolyte wetting of the electrodes. Electrochemical testing was performed in a 30°C constant temperature chamber using a Xinwei battery testing system. Charge and discharge tests were conducted by controlling the charge and discharge current, time, and charging cutoff voltage.

[0083] Example 2 differs from Example 1 in that the raw materials are 2708.2 g of pure magnesium, 240 g of Mg-5Mn and 56.8 g of Mg-30Ce metal block, and the final anode material is Mg-0.5wt.%Ce-0.3wt.%Mn alloy.

[0084] The difference between Comparative Example 1 and Example 1 is that the raw material is only 3000.0 g of pure magnesium metal block, and the final negative electrode material is pure Mg.

[0085] Comparative Example 2 differs from Example 1 in that the raw materials are 2763.0 g of pure magnesium metal block and 240.0 g of Mg-5Mn metal block, and the final anode material is Mg-0.3wt.%Mn alloy.

[0086] Comparative Example 3 differs from Example 1 in that the raw materials are 2890.5 g of pure magnesium metal block and 113.6 g of Mg-30Gd metal block, and the final anode material is Mg-1.0wt.%Gd alloy.

[0087] Comparative Example 4 differs from Example 1 in that the raw materials are 2945.2 g of pure magnesium metal block and 56.8 g of Mg-30Ce metal block, and the final anode material is Mg-0.5wt.%Ce alloy.

[0088] See the attached document for detailed test results. Figures 2-7 .

[0089] Depend on Figure 2 and Figure 3 It can be seen that at 0.3 mA·cm -2 During the long-term charge-discharge cycle of 500h under the specified conditions, the overpotentials of the symmetrical cells in Example 1 and the corresponding three comparative examples, from largest to smallest, were Mg-Mn, Mg, Mg-Gd, and Mg-Gd-Mn. The ternary microalloyed Mg-Gd-Mn alloy had a low overpotential (0.04V), indicating that the synergistic effect of trace amounts of Gd and Mn is beneficial to improving the uniformity and kinetics of magnesium deposition / dissolution and reducing the polarization phenomenon at the interface between the magnesium anode and the electrolyte.

[0090] Depend on Figure 4 It can be seen that at 3mA·cm -2 At this relatively high current density, the longest cycle time among Example 1 and the three comparative symmetric batteries was Mg-Gd-Mn, with a cycle life of 1054h. This indicates that ternary microalloyed Mg-Gd-Mn still has excellent deposition / dissolution stability at this current density, exhibiting the best cycle stability and anti-polarization ability.

[0091] Figure 5The coulombic efficiency of the half-cells in Example 1 and the three comparative examples during the first 200 cycles was compared with that of pure Mg and the other two alloys (Mg-Mn and Mg-Gd). The coulombic efficiency of ternary Mg-Gd-Mn reached 100% earlier and had an average coulombic efficiency of 99.3% during the first 200 cycles.

[0092] Figure 6 Example 2 and the corresponding three comparative examples were performed at 3 mA·cm. -2 The charge-discharge curves at this higher current density exhibit the same pattern as in Example 1, with the longest cycle life observed in the ternary microalloyed Mg-Ce-Mn (over 1100 h). Meanwhile, as... Figure 7 As shown, the charge / discharge capacity is further increased to 5mAh·cm². -2 At that time, ternary microalloyed Mg-Ce-Mn still exhibited the lowest nucleation overpotential and polarization voltage.

[0093] Noting that the standard electrode potentials of Gd (-2.40) and Ce (-2.34) are similar to those of Mg (-2.37), the test results for Mg-Gd and Mg-Ce show that introducing trace amounts of alloying elements with similar electrode potentials can significantly extend the battery cycle life. Meanwhile, the electrochemical test results for the Mg-Gd-Mn and Mg-Ce-Mn examples show that introducing trace amounts of Mn to form a ternary alloy can further extend the battery cycle life. This indicates that Mn can synergistically interact with Gd and Ce to improve the electrochemical performance of the magnesium anode.

[0094] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A microalloyed magnesium alloy anode material, characterized in that, It comprises, by mass percentage, the following components: 0.01 to 2.0 wt.% of Gd or 0.01 to 0.5 wt.% of Ce, 0.01 to 0.3 wt.% of Mn, with the balance being Mg; The microalloyed magnesium alloy anode material is prepared by the following method: raw materials are weighed according to the above component ratio, the raw materials are melted, cast, and air-cooled to obtain an ingot; the raw materials include pure Mg, Mg-Gd master alloy and Mg-Mn master alloy, or the raw materials include pure Mg, Mg-Ce master alloy and Mg-Mn master alloy; the ingot is subjected to solution treatment, extrusion treatment, rolling treatment and annealing treatment in sequence to obtain the microalloyed magnesium alloy anode material.

2. The microalloyed magnesium alloy anode material according to claim 1, characterized in that: The content of impurity elements in the microalloyed magnesium alloy anode material is <0.05 wt.%.

3. A method for preparing a microalloyed magnesium alloy anode material, characterized in that, include: Raw materials are weighed according to the component ratio of the microalloyed magnesium alloy anode material as described in claim 1 or 2, and the raw materials are melted, cast, and air-cooled to obtain an ingot; the raw materials include pure Mg, Mg-Gd master alloy and Mg-Mn master alloy, or the raw materials include pure Mg, Mg-Ce master alloy and Mg-Mn master alloy. The ingot was subjected to solution treatment, extrusion treatment, rolling treatment and annealing treatment in sequence to obtain microalloyed magnesium alloy anode material.

4. The method for preparing the microalloyed magnesium alloy anode material according to claim 3, characterized in that, The process of melting, pouring, and air-cooling solidification of raw materials to obtain ingots specifically includes: The raw materials undergo surface impurity removal treatment; Place the crucible in a melting furnace and preheat it to 300~500℃. Under a protective atmosphere of mixed CO2 and SF6, add pure Mg to the crucible and continue to raise the temperature to 650~700℃. After the pure Mg has completely melted, raise the temperature to 740~760℃ and add the preheated Mg-Gd master alloy and Mg-Mn master alloy or Mg-Ce master alloy and Mg-Mn master alloy. Skim off the slag and stir until the master alloy is completely melted. Stop heating and keep warm for 20-30 minutes, skim off the slag, add refining agent, and stir until the surface of the molten metal becomes mirror-like to obtain the melt; The melt is allowed to stand for 20-30 minutes at a temperature of 740-760℃, and the slag is skimmed off. The melt is then poured into a mold and solidified in the air to obtain an ingot.

5. The method for preparing the microalloyed magnesium alloy anode material according to claim 4, characterized in that: The inner wall of the crucible, the inner surface of the mold, and the parts of the skimming tool and stirring tool that come into contact with the molten metal are uniformly coated with boron nitride paint, and the crucible, mold, skimming tool and stirring tool are preheated and dried at a temperature of 200℃~300℃.

6. The method for preparing the microalloyed magnesium alloy anode material according to claim 3, characterized in that, The solution treatment specifically includes: covering the ingot with aluminum foil, placing the ingot in a stainless steel crucible, covering it with graphite powder to prevent oxidation, and then performing the solution treatment in a heating furnace; the solution treatment temperature is set at 300~400℃, the solution treatment time is set at 8~24h, and the cooling method is water cooling.

7. The method for preparing the microalloyed magnesium alloy anode material according to claim 3, characterized in that, The extrusion process specifically includes: machining the solution-treated ingot into an extrusion billet, and then extruding it at a temperature of 350~450℃.

8. The method for preparing the microalloyed magnesium alloy anode material according to claim 3, characterized in that, The rolling process specifically includes: holding the extruded slab obtained from the extrusion process at a temperature of 250~300℃ for 10~30 minutes, and then rolling it; The rolling passes are 3 to 5, and the reduction of the sheet material in each pass is set to 20 to 30%. After each rolling pass, the sheet material is held at a temperature of 250 to 300°C for 10 to 30 minutes.

9. The method for preparing the microalloyed magnesium alloy anode material according to claim 3, characterized in that: The annealing temperature for the annealing process is set to 300~400℃, and the annealing time is set to 10~30min.

10. The application of a microalloyed magnesium alloy anode material as described in claim 1 or 2 in the anode of a magnesium battery.

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