Mg-Hg-Ga anode material for high-power magnesium-air battery as well as preparation method and application of Mg-Hg-Ga anode material

Abstract

The invention discloses an Mg-Hg-Ga anode material for a high-power magnesium-air battery as well as a preparation method and application of the Mg-Hg-Ga anode material, and belongs to the technical field of electrochemical energy storage power supply electrode materials, the anode material comprises the following components in percentage by weight: 0.06-0.10 wt.% of Hg, 1.55-1.75 wt.% of Ga, and the balance of Mg and inevitable impurities; the microstructure is a single solid solution structure in which alloy elements are uniformly distributed and no second phase is separated out, a heterogeneous composite microstructure is formed by compounding a grain refining area and a grain growing area, the overall grain size is in continuous single-peak distribution, the peak shape is sharp, the distribution is slightly wide, and a separated double-peak or multi-peak phenomenon does not occur. According to the material, through uniform solid solution and microstructure regulation and control of Hg and Ga, a point-surface synergistic corrosion mechanism is achieved, self-stripping of corrosion products can be promoted in the discharge process so as to keep high activity, and hydrogen evolution side reaction and blocking effect can be effectively inhibited. When the material is applied to the magnesium-air battery, high discharge voltage, high specific energy and high anode utilization rate can be obtained at the same time, and the comprehensive performance of the battery is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage power electrode materials technology, specifically relating to a Mg-Hg-Ga anode material for high-power magnesium-air batteries, its preparation method, and its application. Background Technology

[0002] Metal-air batteries, by directly utilizing oxygen from the air as the cathode reactant, eliminate the bulky cathode electrode structure of traditional batteries and possess extremely high theoretical energy density. Studies have shown that the energy density of metal-air batteries can reach 3-30 times that of traditional lithium-ion batteries, demonstrating broad application prospects.

[0003] Among the many available metallic anode materials, magnesium (Mg) stands out due to its relatively negative standard electrode potential (-2.37 V vs. SHE) and high theoretical specific capacity (2.2 A hg). -1 ), and a relatively low density (ρ = 1.74 g cm⁻¹). -3 Abundant crustal reserves (2.08%), low cost ($0.26 g) -1 Magnesium-based primary magnesium-air batteries possess high theoretical discharge voltage (3.09 V) and excellent environmental friendliness, making them one of the most promising anode candidates. Magnesium-based primary magnesium-air batteries exhibit high energy density (6.8 kWh / kg⁻¹). -1 Magnesium-air batteries offer excellent safety and environmental compatibility. Furthermore, they typically employ a neutral electrolyte system, have a simple structure, and can be recycled by replacing the depleted anode. Therefore, they hold significant application potential in areas such as emergency and backup power supplies for peak energy demand and military mobile power sources.

[0004] Despite the numerous advantages of magnesium-air batteries, they still face significant technical bottlenecks in practical applications. Magnesium anodes are prone to severe hydrogen evolution corrosion during discharge, and the resulting corrosion products are difficult to remove in a timely manner. This leads to low anode utilization and discharge voltage, severely hindering their commercialization. To address these issues, researchers typically employ alloying strategies, introducing elements such as Li, Al, Zn, Ca, Mn, Pb, Hg, Ga, Sn, Bi, In, and rare earth elements into the magnesium matrix to increase the hydrogen evolution overpotential and slow down the corrosion rate. During alloying, these elements often introduce a second-phase structure into the microstructure, forming micro-electrical couples with the α-Mg matrix, accelerating α-Mg dissolution, and promoting the removal of the passivation film, thereby enhancing discharge activity to some extent.

[0005] However, traditional alloying strategies primarily rely on the formation of the second phase, which has significant limitations. Larger second-phase particles are prone to detachment during discharge or become encapsulated by corrosion products, leading to a loss of anode material mass and the so-called "block effect." Simultaneously, excessive microgalvanic corrosion can induce severe hydrogen evolution reactions, further reducing anode utilization. Although some studies have mitigated this problem to some extent by optimizing heat treatment and plastic deformation processes to control the size and distribution of the second phase, the overall effect remains limited. Therefore, the design approach of simply relying on the second phase to promote α-Mg dissolution and corrosion film rupture through microgalvanic corrosion to improve discharge activity is insufficient to meet the demands of high-performance magnesium-air battery anode materials. A novel corrosion regulation mechanism that can balance high discharge activity and anode utilization is urgently needed. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a Mg-Hg-Ga anode material for high-power magnesium-air batteries, its preparation method and application, in order to address the shortcomings of the prior art. This invention aims to solve the technical problems of reduced anode utilization caused by block effect and severe hydrogen evolution corrosion due to excessive microgalvanic corrosion in the traditional alloying strategies of existing magnesium-air battery anode materials.

[0007] The present invention adopts the following technical solution: A Mg-Hg-Ga anode material for high-power magnesium-air batteries, comprising, by weight percentage, 0.06-0.10 wt.% Hg, 1.55-1.75 wt.% Ga, with the remainder being Mg and unavoidable impurities; the microstructure of the anode material is a single solid solution structure with uniform distribution of alloying elements and no second phase precipitation, and is a heterogeneous composite microstructure composed of grain refinement region and grain growth region, with the overall grain size exhibiting a continuous single-peak distribution, the peak shape being sharp and the distribution slightly wide, without the appearance of separated double peaks or multi-peak phenomena.

[0008] Preferably, the content of the unavoidable impurities satisfies the following: Fe≤0.016%, Ca≤0.0023%, Mn≤0.0023%, Si≤0.0020%, Cu≤0.0002%, Ni≤0.0004%.

[0009] Preferably, the anode material has an average grain size of 15-25 μm and a strong basal texture, with the maximum strength of the (0001) surface texture being greater than or equal to 11.5.

[0010] Another technical solution of the present invention is a method for preparing Mg-Hg-Ga anode material for high-power magnesium-air batteries, comprising the following steps: S1. Using magnesium matrix raw materials, Ga raw materials and Mg-15Hg master alloy as raw materials, calculate and weigh each raw material according to the target composition; S2. Polish all raw materials to remove oxide scale; S3. Place the magnesium matrix raw material in a crucible and melt it at 720°C under a protective atmosphere. After it is completely melted, add the Mg-15Hg master alloy and Ga raw material in sequence, stir for 30 minutes and then remove the slag. S4. The refined melt is cast into an ingot at 720℃ using a water-cooled copper mold, with the cooling rate controlled at 50℃ / s. S5. Keep the ingot at 355-365℃ for 8 hours; S6. After solution treatment, directly heat to 395-405℃ and keep warm for 4 hours; S7. Slowly cool to 350°C at a rate of 50°C / h; S8. After holding at 350℃ for 30 minutes, transfer to an extrusion die preheated to 350℃, with a total transfer time of ≤3 minutes; S9. Under the condition that the temperature of the mold, extrusion device and billet are all 350℃, hot extrusion is carried out at an extrusion speed of 1m / min to obtain a sheet. S10. The extruded sheet is subjected to low-temperature stabilization and pulse excitation treatment in sequence, and finally water quenched to room temperature to obtain Mg-Hg-Ga anode material for high-power magnesium-air batteries.

[0011] Preferably, in step S1, magnesium ingots with a purity ≥ 99.99 wt.%, gallium with a purity ≥ 99.99 wt.%, and Mg-15Hg master alloy are used as raw materials and weighed according to the target composition.

[0012] Preferably, in step S3, the protective atmosphere is argon.

[0013] Preferably, in step S4, the casting process maintains an argon protective atmosphere, and the diameter of the ingot is 95 mm.

[0014] Preferably, in step S9, the hot extrusion ratio is 44:1; the width of the sheet is 80mm and the thickness is 2mm.

[0015] Preferably, step S10 specifically includes: a. Low-temperature stabilization: The extruded sheet was left to stand at 305℃ for 40 seconds; b. Pulse excitation treatment: The plate material that has been stabilized at low temperature is quickly transferred to an environment of 385-395℃ and subjected to instantaneous heat treatment for 8 seconds; c. Water quenching: The plate after pulse excitation treatment is quickly water quenched to room temperature.

[0016] Another technical solution of the present invention is the application of Mg-Hg-Ga anode material for high-power magnesium-air batteries in magnesium-air batteries.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: A high-power magnesium-air battery Mg-Hg-Ga anode material directly avoids the formation of harmful coarse second phases through the uniform solid solution of Hg and Ga, eliminating the risk of block effect at its source. Simultaneously, the precisely designed heterogeneous composite structure provides the material basis for a novel point-to-surface synergistic corrosion mechanism. This structure not only provides abundant discharge active sites through the high-energy grain boundaries in the fine-grained region, enhancing electrochemical activity, but also utilizes the relative stability of the grain-growing region to suppress the overall hydrogen evolution rate, thus fundamentally solving the core contradiction in magnesium-air batteries where discharge activity and anode utilization are difficult to achieve simultaneously.

[0018] Furthermore, impurities such as Fe and Ni in magnesium alloys easily form micro-galvanic corrosion nuclei, accelerating hydrogen evolution reactions and reducing anode utilization. Excessive impurities such as Ca and Si lead to uneven microstructure, affecting the stripping of corrosion products. By precisely controlling the impurity threshold, harmful galvanic pairs are avoided between impurities and the matrix, reducing the induction of hydrogen evolution corrosion. At the same time, the uniform solid solution of Hg and Ga elements in the Mg matrix is ​​ensured, preventing the precipitation of second phases induced by impurities. This significantly improves the performance consistency of materials prepared in different batches, solving the problems of poor discharge stability and large batch differences caused by uncontrolled impurity content in existing technologies, and providing an operable quality control standard for industrial production.

[0019] Furthermore, this grain size range is a direct result and quantitative manifestation of the heterogeneous composite microstructure formed under the specific thermomechanical process, ensuring the optimization of the size and proportion of the fine-grained region and the grain growth region, and is an ideal scale for achieving point-surface synergy. Strong basal texture means that the (0001) close-packed planes of most grains tend to be parallel to the extrusion direction. Due to the dense basal atomic arrangement and low surface energy of magnesium, this texture orientation helps reduce the overall chemical activity of the material surface, improves resistance to uniform corrosion, and thus helps suppress hydrogen evolution side reactions, providing additional crystallographic structural support for high anodic efficiency.

[0020] A method for preparing Mg-Hg-Ga anode material for high-power magnesium-air batteries is disclosed. The process begins with high-purity raw material melting to ensure compositional purity and initial homogenization. This is followed by specific solution and homogenization heat treatments to achieve complete Hg and Ga dissolution while preventing any second-phase precipitation. Precisely temperature-controlled hot extrusion induces dynamic recrystallization, forming a uniform fine-grained matrix. Finally, the core process involves low-temperature stabilization and pulse-excitation online heat treatment to selectively induce minority grain growth, resulting in the desired fine-grained / grain-growth heterogeneous composite structure with a single-peak distribution. Through synergistic control of process parameters, precise regulation of material composition, solution state, and microstructure is achieved, enabling the reproducible preparation of high-performance anode materials.

[0021] Furthermore, high-purity magnesium ingots and gallium can avoid excessive levels of harmful impurities in low-purity raw materials, reducing the core corrosion of microcouples. The Mg-15Hg master alloy utilizes precisely controlled Hg content, avoiding compositional inhomogeneity caused by direct Hg addition. Strict requirements for raw material purity ensure uniform solid solution of Hg and Ga within the magnesium matrix, preventing second-phase precipitation caused by impurities and providing a prerequisite for subsequent microstructure control. This reduces batch-to-batch performance differences, improves the stability of key indicators such as discharge specific energy and anode utilization rate, while reducing the difficulty of subsequent process control and minimizing scrap rates due to raw material impurities.

[0022] Furthermore, magnesium readily reacts with oxygen at 720℃ to form oxide scale, leading to uneven melt composition and increased inclusions in the ingot, affecting subsequent processing and electrochemical performance. Argon, as an inert gas, isolates the melt from air, preventing oxidation of magnesium and alloying elements and ensuring melt purity; it also prevents the volatilization of Hg, ensuring precise achievement of the target composition. This limitation makes the smelting process stable and controllable, resulting in a dense ingot structure free of oxide inclusions, providing high-quality billets for subsequent solution treatment, extrusion, and other processes, and solving the problems of compositional deviation and performance degradation caused by inappropriate protective atmospheres in existing technologies.

[0023] Furthermore, the casting stage maintains argon protection, continuing the anti-oxidation and anti-Hg volatilization design from the smelting stage to ensure compositional consistency. The 95mm ingot diameter is suitable for subsequent hot extrusion processes, avoiding uneven extrusion due to excessive diameter or low production efficiency due to insufficient diameter. A cooling rate of 50℃ / s inhibits excessive grain growth, reduces intragranular segregation, and ensures a dense and uniform ingot microstructure. This solves the problems of ingot porosity and compositional segregation caused by ambiguous casting parameters in existing technologies, allowing the ingot to meet extrusion requirements without complex post-processing, shortening the production process, reducing costs, and providing a uniform initial microstructure for subsequent microstructure control, ensuring stable performance of the final product.

[0024] Furthermore, the 44:1 extrusion ratio induces complete dynamic recrystallization through intense plastic deformation, forming uniform and fine initial grains, which lays the foundation for constructing heterogeneous composite structures through subsequent online heat treatment. The reasonable range of the extrusion ratio avoids insufficient grain refinement due to being too small, or cracking and uneven performance of the sheet due to being too large.

[0025] Furthermore, low-temperature stabilization eliminates residual extrusion stress, bringing the grain boundaries to a metastable state and preparing for selective grain growth. Pulse excitation treatment induces the directional growth of some grains through instantaneous high temperature, forming a structure where fine-grained regions and grain-growing regions coexist, while avoiding excessive grain coarsening. The water quenching step rapidly fixes this heterogeneous structure, preventing microstructural evolution during cooling. The precise matching of parameters in the three-step process solves the problem of accurately controlling grain size distribution in traditional heat treatment, ensuring a single-peak grain size distribution and fully leveraging the point-surface synergistic corrosion mechanism.

[0026] The application of Mg-Hg-Ga anode material in high-power magnesium-air batteries broadens the application scenarios of high-performance anode materials and highlights the practical value of the technical solution. Existing magnesium-air battery anode materials suffer from a trade-off between discharge activity and anode efficiency, making it difficult to meet the demands of high-end applications such as marine equipment and emergency power supplies. The material of this invention, with its high discharge specific energy, high anode utilization rate, and good stability, can be directly adapted to magnesium-air batteries with neutral electrolyte systems, solving the problem of insufficient performance of traditional anode materials under high-power discharge.

[0027] In summary, this invention addresses the block effect and hydrogen evolution corrosion problems of traditional anode materials through precise Mg-Hg-Ga ratio and heterogeneous composite microstructure design, while also achieving high discharge activity, high utilization rate, and stability. The process parameters are scientifically controllable, suitable for industrial production, and applicable to a wide range of scenarios.

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the following description of the relative embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The images are scanning electron microscope (SEM) images of the Mg-Hg-Ga anode material obtained in Example 1, where (a) shows the uniform microstructure of the Mg-Hg-Ga anode material at low magnification (without obvious second phase), and (b) shows the uniform distribution of alloying elements (Hg, Ga) in the magnesium matrix at high magnification. Figure 2 The X-ray diffraction (XRD) pattern of the Mg-Hg-Ga anode material obtained in Example 1; Figure 3 The image shows the electron backscatter diffraction (EBSD) pattern of the Mg-Hg-Ga anode material obtained in Example 1, where (a) is the crystal orientation diagram of the Mg-Hg-Ga anode material, (b) is the (0001) plane pole diagram, and (c) is the single-peak distribution curve of the grain size. Figure 4 The hydrogen evolution test results are shown for the Mg-Hg-Ga anode material obtained in Example 1 and the typical commercial AZ31 anode material of the comparative example after immersion in 3.5 wt.% NaCl solution for 48 h. Figure 5 The Mg-Hg-Ga anode material obtained in Example 1 and the typical commercial AZ31 anode material of the comparative example were tested in 3.5 wt.% NaCl solution at 1-20 mA·cm. -2 The half-cell galvanostatic curves at current densities, where (a) represents 1 mA. cm -2 The discharge curve at current density, (b) is 5mA. cm -2 The discharge curve at current density, (c) is 10mA cm -2 Discharge curve at current density, (d) is 15mA cm -2 The discharge curve at current density (e) is 20 mA. cm -2 Discharge curves at current density; Figure 6 The Mg-Hg-Ga anode material obtained in Example 1 and the typical commercial AZ31 anode material of the comparative example were tested in 3.5 wt.% NaCl solution at 1-20 mA·cm. -2 The full-cell galvanostatic curves at current densities, where (a) represents 1 mA. cm -2 The discharge curve at current density, (b) is 5mA. cm -2 The discharge curve at current density, (c) is 10mA cm -2 Discharge curve at current density, (d) is 15mA cm -2 The discharge curve at current density (e) is 20 mA. cm -2 Discharge curves at current density; Figure 7The graph shows the relationship between anode efficiency and current density for the Mg-Hg-Ga anode material obtained in Example 1 and the typical commercial AZ31 anode material in the comparative example. Figure 8 The graph shows the relationship between discharge specific energy and current density for the Mg-Hg-Ga anode material obtained in Example 1 and the typical commercial AZ31 anode material in the comparative example. Figure 9 The Mg-Hg-Ga anode material obtained in Example 1 was subjected to 5 mA·cm -2 The surface morphology of the corrosion products after discharge at current density for 2 hours is shown in the following images: (a) shows the surface morphology of the flat area and corrosion pits coexisting under low magnification; (b) shows the cracks and exposed substrate of the corrosion product layer in the area selected by the red box in (a); and (c) shows the EDS distribution of Hg and Ga elements in (b). Figure 10 The Mg-Hg-Ga anode material obtained in Example 1 was subjected to 1-20 mA·cm 2 The surface morphology of the decorrosion products after 10 hours of discharge at a current density, where (a) and (b) are images of the 1 mA discharge. cm -2 SEM morphology of the lower flat area and the pitted area, (c) and (d) are respectively 5mA cm -2 SEM morphology of the lower flat area and the pitted area, (e) and (f) are respectively 10 mA cm -2 SEM morphology of the lower flat area and pitted area, (g) at 15mA cm -2 The overall SEM morphology is relatively uniform, with an amplitude of 20 mA. cm -2 The overall SEM morphology is relatively uniform. Figure 11 The Mg-Hg-Ga anode material obtained in Example 1 was subjected to 20 mA·cm 2 Cross-sectional morphology after 2 hours of discharge at current density. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0033] This invention provides a Mg-Hg-Ga anode material for high-power magnesium-air batteries, its preparation method, and its application. It selects two liquid metal elements with high hydrogen evolution overpotentials—mercury (Hg) and gallium (Ga). Studies have shown that these two elements, while mitigating hydrogen evolution corrosion, can promote the self-exfoliation of corrosion products through a dissolution-redeposition mechanism, thereby effectively enhancing the anode discharge activity. This invention achieves uniform solid solution of both elements in a magnesium matrix, fundamentally avoiding the formation of traditional second-phase particles. Furthermore, by combining hot extrusion and heat treatment processes to control the microstructure, an innovative heterogeneous composite microstructure with coexisting fine-grained and grain-growing regions is constructed. This structure exhibits a "point-surface synergistic" corrosion mechanism during discharge, effectively promoting the self-exfoliation of corrosion products and the continuous renewal of the active surface, thus significantly improving discharge activity. Specifically, the fine-grained region provides high-energy grain boundaries as highly active reaction "points," preferentially causing pitting corrosion and promoting product shedding; while the grain-growing region, as a relatively stable reaction "surface," induces cracks through the expansion stress generated by corrosion products, providing ion transport channels. This synergistic effect enables the electrolyte to fully penetrate the anode surface during discharge, significantly improving the anode's electrochemical activity. Simultaneously, the grain growth regions in the heterogeneous composite structure, due to their lower grain boundary density and more stable crystal orientation, exhibit a relatively low corrosion rate, effectively buffering the overall self-corrosion tendency during discharge and thus significantly suppressing the anode hydrogen evolution side reaction, improving anode utilization. Furthermore, the sharp and narrow unimodal grain size distribution effectively reduces the microscopic electrochemical inhomogeneity caused by grain size differences. This helps reduce local current concentration during discharge, thereby promoting more uniform anode dissolution at high current densities and improving discharge stability.

[0034] This invention discloses a method for preparing Mg-Hg-Ga anode material for high-power magnesium-air batteries. Through specific alloy design and process control, the microstructure is precisely regulated to ensure that the material possesses excellent comprehensive discharge performance. The method includes the following steps: S1. Raw material preparation: Magnesium ingots with a purity ≥99.99 wt.%, gallium with a purity ≥99.99 wt.%, and Mg-15Hg master alloy are used as raw materials and weighed according to the target composition.

[0035] High-purity magnesium ingots (99.99 wt%), high-purity gallium (99.99 wt%), and Mg-15Hg (weight percentage) master alloy were used as raw materials. The raw materials were calculated and weighed according to the target composition. S2. Surface treatment: All raw materials are surface-polished to remove oxide scale until a clean metal surface is exposed. S3. Melting and casting: Place the magnesium matrix raw material in a crucible and melt it at 720°C under a protective atmosphere. After it is completely melted, add the Mg-15Hg master alloy and Ga raw material in sequence, stir for 30 minutes and then remove the slag. Preferably, the pretreated high-purity magnesium ingot is placed in a crucible and melted in a resistance furnace at 720°C under an argon protective atmosphere. After the magnesium ingot is completely melted, the furnace temperature is kept stable at 720°C, and Mg-15Hg master alloy and high-purity gallium are added sequentially. The mixture is mechanically stirred for 30 minutes to ensure that the alloying elements are fully diffused and the melt composition is uniform. Then, slag removal is performed. S4. Semi-continuous casting: The refined melt is cast at 720℃ using a water-cooled copper mold to prepare an ingot with a diameter of 95mm. The cooling rate is controlled at 50℃ / s. Preferably, the refined melt is semi-continuously cast at 720°C using a water-cooled copper mold to prepare an ingot with a diameter of 95 mm. A stable argon protective atmosphere is maintained during the casting process, and the cooling rate is controlled at 50°C / s to obtain a cast billet with uniform composition and dense structure. S5. Solution treatment: Hold the ingot at 355-365℃ for 8 hours; Preferably, the ingot is placed in an air-circulating furnace and held at 360°C for 8 hours to allow Hg and Ga alloying elements to fully dissolve in the Mg matrix and reduce intragranular segregation. S6. Homogenization treatment: After solution treatment, directly heat to 395-405℃ and keep warm for 4 hours; Preferably, after the solution treatment is completed, the furnace temperature is raised to 400°C and held for 4 hours without cooling, so as to further promote the full diffusion of alloying elements, eliminate micro-composition fluctuations, and achieve atomic-scale composition homogenization. The selected temperatures are all higher than the recrystallization temperature of Mg but lower than the melting point of Mg, which can effectively promote the diffusion of Hg and Ga atoms and eliminate intracrystalline segregation.

[0036] S7. In-furnace programmed temperature control cooling: slowly cool to 350℃ at a rate of 50℃ / h; Preferably, after homogenization, the material is cooled in a furnace under programmed temperature control at a rate of 50°C / h to 350°C to obtain an extruded billet with uniform composition and low internal stress. Selecting a suitable temperature and a relatively slow cooling rate is beneficial to achieving complete solid solution and avoiding the precipitation of a second phase.

[0037] S8. Rapid heat preservation and transfer: After heat preservation at 350℃ for 30 minutes, transfer to an extrusion mold preheated to 350℃, with a total transfer time of ≤3 minutes; Preferably, after the billet is briefly kept at 350°C for 30 minutes, it is quickly transferred to an extrusion die preheated to 350°C. A heat preservation device is used during the transfer process, and the total time is controlled within 3 minutes to minimize heat loss. Remove the billet from the preheated fixture, place it immediately in the insulation pad, and quickly transport it to the extruder within 3 minutes to minimize heat loss.

[0038] S9. Hot extrusion: Under the condition that the temperature of the die, extrusion device and billet are all 350℃, hot extrusion is carried out at an extrusion speed of 1m / min. The extrusion ratio of hot extrusion is 44:1, and a sheet with a width of 80mm and a thickness of 2mm is obtained. Preferably, the extrusion device is equipped with a flat extrusion die, the die outlet cross section of which is 80mm (width) * 2mm (thickness).

[0039] Preferably, the hot extrusion ratio is about 44:1, which induces complete dynamic recrystallization through intense plastic deformation, forming uniform and fine initial recrystallized grains.

[0040] S10. Online heat treatment: a. Low-temperature stabilization: The extruded sheet is immediately passed through a temperature-controlled environment of 305℃ and left to stand for 40 seconds; b. Pulse excitation treatment: Subsequently, the sheet is quickly transferred to a heating device of 385-395℃ for instantaneous heat treatment for 8 seconds; c. Water quenching: After pulse excitation treatment, the sheet is quickly water quenched to room temperature.

[0041] The low-temperature stabilization step helps eliminate some of the residual stress generated by extrusion, provides limited atomic kinetic energy, and puts the grain boundary energy in a "metastable" high-energy state, preparing for subsequent instantaneous excitation. Furthermore, the selected temperature is lower than the recrystallization temperature, which helps avoid excessive recovery and ensures that the fine recrystallized grains are not significantly coarsened.

[0042] The pulsed excitation process should be instantaneous to ensure that only a few grains with optimal orientation and highest grain boundary mobility can obtain enough energy to grow rapidly, thus forming a heterogeneous composite structure in which grain growth and grain refinement regions coexist. Due to the extremely short time, the size of the grown grains is limited to a relatively concentrated range, thus forming a sharp, narrow and slightly wide single-peak distribution together with the fine grains of the matrix, rather than separate double or multi-peak distributions. This is beneficial for the anode to achieve uniform discharge at high current densities, thereby improving the battery's operational stability and service life.

[0043] The water quenching step helps ensure that the heterogeneous composite structure is completely preserved and prevents further changes during slow cooling.

[0044] A high-power magnesium-air battery Mg-Hg-Ga anode material, prepared by the above method, comprises, by weight percentage: Hg 0.06-0.10 wt.%, Ga 1.55-1.75 wt.%, with the remainder being Mg and unavoidable impurities (Fe≤0.016%, Ca≤0.0023%, Mn≤0.0023%, Si≤0.0020%, Cu≤0.0002%, Ni≤0.0004%). The microstructure of this anode material exhibits: uniform distribution of alloying elements, no second-phase precipitation, and a microstructure composed of a composite of grain refinement and grain growth regions. The overall grain size shows a continuous single-peak distribution with sharp peaks and a slightly wide distribution, without any separated bimodal or multimodal phenomena. The average grain size is 15-25 μm.

[0045] The Mg-Hg-Ga anode material exhibits a microstructure characterized by uniform solid solution of alloying elements and absence of second-phase precipitation, forming a heterogeneous composite structure with coexisting fine-grained and coarse-grained regions and a unimodal grain size distribution. This structure, through the dissolution and redeposition of Hg and Ga and a "point-to-surface synergistic" corrosion mechanism, significantly enhances discharge activity while maintaining high anode utilization, thus effectively solving the problem of simultaneously achieving high discharge activity and anode efficiency in magnesium-air batteries.

[0046] The magnesium-mercury-gallium alloy anode material prepared by this invention possesses both high discharge activity and high anode efficiency, effectively reconciling the contradiction between "activation" and "passivation" during the discharge process of traditional anode materials. It provides a new theoretical approach and process route for developing high-performance magnesium-air battery anode materials, demonstrating significant innovation and application value.

[0047] This invention discloses a Mg-Hg-Ga anode material for high-power magnesium-air batteries, which can be used in magnesium-air batteries for applications in marine equipment, field emergency power supplies, military backup power supplies, or civilian emergency power supply systems.

[0048] By benchmarking the discharge performance of typical commercial AZ31 magnesium alloy anode materials, the superiority and application potential of the Mg-Hg-Ga anode material of this invention were evaluated and highlighted.

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0050] Example 1 This embodiment provides a Mg The preparation method of Hg-Ga anode material is as follows: 1. The Mg-Hg-Ga anode material of this embodiment is prepared from the following raw materials by mass percentage: 0.08wt.%Hg, 1.65wt.%Ga, with the remainder being Mg and unavoidable impurities (Fe≤0.016%, Ca≤0.0023%, Mn≤0.0023%, Si≤0.0020%, Cu≤0.0002%, Ni≤0.0004%). The microstructure of this anode material is characterized by: uniform distribution of alloying elements, no second phase precipitation, and its microstructure is composed of a composite of grain refinement and grain growth regions. The overall grain size exhibits a continuous single-peak distribution with sharp peaks and a slightly wide distribution, without any separated double or multi-peak phenomena. The average grain size is 18.07±0.57μm, and the maximum strength of the (0001) plane texture is 16.07.

[0051] 2. Raw material preparation: High-purity magnesium ingots (99.99 wt%), high-purity gallium (99.99 wt%) and Mg-15Hg (weight percentage) master alloy are used as raw materials. Calculate and weigh each raw material according to the target composition. 3. Surface treatment: All raw materials are polished to remove oxide scale until a clean metal surface is exposed; 4. Melting and Casting: The pretreated high-purity magnesium ingots are placed in a crucible and melted in a resistance furnace at 720℃ under an argon protective atmosphere. After the magnesium ingots are completely melted, the furnace temperature is kept stable at 720℃, and Mg-15Hg master alloy and high-purity gallium are added sequentially. The mixture is mechanically stirred for 30 minutes to ensure sufficient diffusion of alloying elements and uniform composition of the melt. Then, slag removal is performed. 5. Semi-continuous casting: The refined melt is semi-continuously cast at 720℃ using a water-cooled copper mold to prepare ingots with a diameter of 95mm. A stable argon protective atmosphere is maintained during the casting process, and the cooling rate is controlled at 50℃ / s to obtain a cast billet with uniform composition and dense structure. 6. Solution treatment: Place the ingot in an air-circulating furnace and hold it at 360℃ for 8 hours to allow Hg and Ga alloying elements to fully dissolve in the Mg matrix and reduce intragranular segregation; 7. Homogenization treatment: After solution treatment, without cooling, the furnace temperature is directly raised to 400℃ and held for 4 hours to further promote the full diffusion of alloying elements, eliminate micro-composition fluctuations, and achieve atomic-scale composition homogenization. 8. In-furnace temperature controlled cooling: After homogenization, the extruded billet is cooled in the furnace at a rate of 50℃ / h to 350℃, so as to obtain a uniform composition and low internal stress. 9. Rapid heat preservation and transfer: After briefly heat preservation at 350℃ for 30 minutes, the billet is quickly transferred to the extrusion die preheated to 350℃. The heat preservation device is used during the transfer process, and the total time is controlled within 3 minutes to minimize heat loss. 10. Hot extrusion: Under the condition that the temperature of the mold, extrusion device and billet are all stable at 350℃, hot extrusion is carried out at an extrusion speed of 1m / min to obtain a sheet with a width of 80mm and a thickness of 2mm. 11. Online heat treatment: a. Low temperature stabilization: The extruded sheet is immediately passed through a temperature-controlled environment of 305℃ and left to stand for 40 seconds; b. Pulse excitation treatment: Subsequently, the sheet is quickly transferred to a heating device of 390℃ for instantaneous heat treatment for 8 seconds; c. Water quenching: After pulse excitation treatment, the sheet is quickly water quenched to room temperature.

[0052] 12. The heat-treated magnesium alloy was processed into samples of fixed size by wire cutting, and then subjected to sandpaper grinding and polishing to completely remove the surface oxide layer and contaminants. The samples were then used for microstructure characterization and discharge performance testing.

[0053] 13. For this anode material at 1-20mA cm -2 Discharge performance was tested at current density, and its discharge specific energy was 1182-1930 mWh. g -1 The anode utilization rate was 51.3-63.9% at 5mA. cm -2 The energy density reaches its peak at the current density, with peak discharge specific energy and anode utilization rate of 1930 mWh. g -1And 61.4%, and at 15 and 20 mA cm -2 Uniform discharge was achieved at high current density. This embodiment demonstrates excellent and balanced overall discharge performance, making it suitable for high-power water-activated batteries, emergency power reserves, and magnesium anodes for marine instruments, among other applications requiring comprehensive discharge performance.

[0054] Example 2 The difference between this embodiment and Embodiment 1 is as follows: In this embodiment, the components and weight percentages of the magnesium alloy anode material are: Hg 0.06wt.%, Ga 1.55wt.%, with the remainder being Mg and unavoidable impurities. The solution treatment temperature is adjusted to 355℃, the homogenization treatment temperature is adjusted to 395℃, and the remaining steps are the same as in Embodiment 1. The reduction in alloy element content weakens the solute dragging effect. Under the same thermomechanical treatment conditions, it is expected that a heterogeneous composite structure with coexisting grain refinement and growth regions can still be formed, but the proportion and size of the grain growth region will increase. The expected average grain size is 19-22μm, and the maximum strength of the (0001) basal texture is expected to be no less than 13.0. Due to the retention of heterogeneous structural characteristics but the reduction in Hg and Ga content, the expected peak discharge specific energy is 1890-1930mWh·g. -1 Regarding anode utilization, a moderate increase in the grain growth region helps to slow down the local corrosion rate, but the reduction in alloying elements weakens hydrogen evolution inhibition. Under the combined effect, the expected anode utilization is 59.5-61.0%. This embodiment reduces raw material costs while maintaining the heterogeneous structure, making it suitable for cost-sensitive civilian emergency power supplies and backup batteries with moderate requirements for discharge performance.

[0055] Example 3 The difference between this embodiment and Embodiment 1 is as follows: In this embodiment, the components and weight percentages of the magnesium alloy anode material are: Hg 0.10wt.%, Ga 1.75wt.%, with the remainder being Mg and unavoidable impurities. The solution treatment temperature is adjusted to 365℃, the homogenization treatment temperature is adjusted to 405℃, and the remaining steps are the same as in Embodiment 1. The increased content of alloying elements (especially Ga) enhances the solute dragging effect, and it is expected that a heterogeneous composite structure can still be formed, but the grain growth process is suppressed, the proportion of the refined region increases, and the development of the grain growth region is insufficient. The expected average grain size is 17-19μm, and the maximum intensity of the (0001) basal texture is predicted to be no less than 15.0. The higher proportion of fine grain regions under the heterogeneous structure provides a high density of active sites, thereby improving the electrochemical activity. The expected peak discharge specific energy is 1920-1960mWh·g. -1Regarding anode utilization, a higher alloy element content is beneficial for suppressing hydrogen evolution, but an increased proportion of refined regions may lead to an increase in high-energy grain boundary density, which in turn exacerbates localized electrochemical corrosion and hydrogen evolution side reactions. Therefore, the expected anode utilization is 60.0-61.5% under the combined effect. This embodiment is also applicable to emergency power supply systems with high requirements for power density and energy output.

[0056] Example 4 The difference between this embodiment and Embodiment 1 is that the pulse excitation temperature is adjusted to 385℃, while the remaining steps are the same as in Embodiment 1. The lower pulse temperature results in insufficient thermal driving force for grain growth, leading to a significant reduction in the expected grain growth region, weakening the heterogeneous composite structure characteristics, and causing the microstructure to tend towards a homogeneous state dominated by refined regions. The expected average grain size is 15-17 μm, and the maximum intensity of the (0001) basal texture is predicted to be no less than 12.0. Although the uniform fine-grained microstructure provides a high density of active sites, which is beneficial for improving discharge activity, it also significantly increases the total area of ​​grain boundaries. The higher energy state and faster ion diffusion channels at the grain boundaries exacerbate local electrochemical corrosion and hydrogen evolution side reactions. Therefore, the expected peak discharge specific energy is 1910-1940 mWh·g. -1 The anode utilization rate is 57.0-59.5%. This embodiment is suitable for fast-response emergency power supplies with high requirements for start-up speed and instantaneous power.

[0057] Example 5 The difference between this embodiment and Embodiment 1 is that the pulse excitation treatment temperature is adjusted to 395℃, while the remaining steps are the same as in Embodiment 1. The higher pulse temperature enhances the driving force for grain growth, and the proportion of "grain growth regions" in the microstructure is expected to increase, while the uniformity of grain size distribution is slightly lower than in Embodiment 1. The expected average grain size is 20-25 μm, and the maximum strength of the (0001) basal texture is expected to be no less than 11.5. In this embodiment, the proportion of coarse-grained regions is higher, and the overall density of active reaction sites in the material decreases, leading to a reduction in electrochemical activity. Simultaneously, the increased difference in grain size exacerbates microscopic electrochemical inhomogeneity, forming a strong microscopic electrocouple effect. This leads to increased non-uniform dissolution and a higher hydrogen evolution rate. Under the combined effect, the expected peak discharge specific energy is 1870-1920 mWh·g. -1 The anode utilization rate is 55.5-58.0%. This embodiment is suitable for large-scale manufacturing scenarios with high energy density requirements and large tolerance for temperature control in the production process.

[0058] Comparative Example This comparative example uses commercially available AZ31 magnesium alloy anode material with the following chemical composition: 3.47 wt.% Al, 0.84 wt.% Zn, with the balance being Mg and unavoidable impurities (Fe≤0.0085%, Ca≤0.0022%, Mn≤0.3000%, Si≤0.0100%, Cu≤0.0008%, Ni≤0.0020%). After wire cutting to prepare the sample, the alloy underwent surface grinding and polishing treatments before performance testing.

[0059] Experimental test results (1) Original tissue and structural analysis Figure 1 The original microstructure of Example 1 is shown, exhibiting a uniform structure with no obvious second phase observed. Corresponding EDS analysis results indicate that Hg and Ga elements are uniformly distributed within the magnesium matrix. Figure 2 The XRD pattern of Example 1 shows that all diffraction peaks correspond to the α-Mg phase, and no other phases were detected, confirming that the alloy has a single solid solution structure. Figure 3 (a)-(c) show the crystal orientation diagram, (0001) pole figure, and grain size distribution curve of Example 1, respectively. Analysis indicates that the alloy consists of a heterogeneous composite structure composed of fine-grained and grain-growing regions. The grain size exhibits a unimodal distribution, with the overall distribution curve being sharp and slightly shifted towards coarse grains, and the average grain size is approximately 18.07 μm. Pole figure analysis shows that the structure possesses strong basal texture, with the (0001) texture reaching a maximum strength of 16.07. Due to the dense atomic arrangement and low surface energy of the magnesium alloy basal plane, this texture characteristic helps improve the material's corrosion resistance, thus providing a structural basis for suppressing hydrogen evolution reaction and improving anode utilization efficiency.

[0060] (2) Analysis of hydrogen evolution corrosion behavior Figure 4The hydrogen evolution kinetics curves of Mg-Hg-Ga (Example 1) and AZ31 (Comparative Example) are shown. It can be seen that the hydrogen evolution process of the alloys can be divided into three characteristic stages: an initial rapid increase, followed by a gradual decrease and eventually stabilization. This kinetic behavior is closely related to the dynamic equilibrium process of oxide film rupture, corrosion product formation, and subsequent adhesion and peeling on the magnesium alloy surface. In the first stage, the hydrogen evolution rate of the Mg-Hg-Ga alloy is significantly higher than that of AZ31, indicating that its surface oxide film is more prone to rupture or peeling, exposing more active reaction sites and reflecting higher initial reactivity. In the second stage, corrosion product layers form on the surfaces of both alloys, and the hydrogen evolution rate decreases significantly and becomes similar. In the third stage, the formation and peeling of corrosion products gradually reach a dynamic equilibrium, and the hydrogen evolution rate remains at a low level without a significant increase; however, the hydrogen evolution rate of Mg-Hg-Ga increases slightly, suggesting that its corrosion product layer has better self-peeling ability, which helps maintain the active interface during the discharge process. Overall, the average hydrogen evolution rate of the Mg-Hg-Ga alloy is comparable to that of AZ31, remaining at a relatively low level, which is beneficial for suppressing hydrogen evolution side reactions and thus improving anode utilization efficiency.

[0061] (2) Discharge performance evaluation Figure 5 The figures show the half-cell galvanostatic discharge curves of Mg-Hg-Ga and the comparative example AZ31 in Example 1. The results show that Mg-Hg-Ga exhibits galvanostatic discharge characteristics at 1, 5, 10, 15, and 20 mA·cm⁻¹. 2 The discharge potentials at the current densities were -2.00, -2.01, -1.98, -1.97, and -1.87 V (vs. SCE), all of which were significantly negative compared to AZ31, indicating that it has higher electrochemical activity. Figure 6 The full-cell galvanostatic discharge curves for both are shown, further demonstrating the effects of Mg-Hg-Ga at 1, 5, 10, 15, and 20 mA·cm⁻¹. 2 The discharge potentials at the current densities were 1.86, 1.72, 1.59, 1.44, and 1.31 V, respectively, all significantly higher than those of AZ31. This result corroborates the low Mg-Hg-Ga potential observed in the half-cell test, jointly confirming its excellent discharge activity. Based on Figure 5 and Figure 6 Based on the test data, the anode utilization efficiency and discharge specific energy were calculated, and the results are shown in the figure. Figure 7 and Figure 8 .from Figure 7 It can be seen that Mg-Hg-Ga at 1-20 mA·cm 2The anodic utilization efficiency at current density was 51.3-63.9%, slightly lower than AZ31, but still at a high level overall, with little difference between the two. This phenomenon can be attributed to the fact that both materials exhibited low hydrogen evolution rates. Figure 8 The results show that Mg-Hg-Ga at 1-20 mA·cm 2 The energy density at the current density is 1182 1930mWh·g 1 In most discharge current densities (5-20 mA·cm⁻¹) 2 Under these conditions, the discharge specific energy of Mg-Hg-Ga is significantly higher than that of AZ31, demonstrating its comprehensive advantages in energy output.

[0062] (3) Corrosion morphology analysis Figure 9 Example 1 demonstrates the Mg-Hg-Ga alloy at 5 mA·cm⁻¹ 2 Corrosion morphology after 2 hours of discharge at current density. Figure 9 (a) The low-magnification SEM image shows that the Mg-Hg-Ga surface exhibits a coexistence of flat areas and corrosion pits. Figure 9 (b) is Figure 9 (a) The high-magnification SEM image of the selected area further shows that the corrosion product layer in the flat region contains a large number of cracks and has an exposed substrate, which confirms its self-exfoliation characteristics. This structure is beneficial for maintaining electrolyte penetration and interfacial material transport during the discharge process. EDS analysis shows that Hg and Ga exist in the corrosion product layer and are significantly redeposited at cracks and defects, which verifies the dissolution-redeposition mechanism of Hg and Ga elements in promoting the exfoliation of discharge products. In summary, the corrosion behavior of this material is mainly manifested by a unique "point-surface synergy" mechanism: the fine-grained region provides high-energy grain boundaries as highly active reaction "points," preferentially causing pitting corrosion and promoting product detachment; while the grain-grown region acts as a relatively stable reaction "surface," inducing cracks through the expansion stress generated by the corrosion products, providing ion transport channels. This synergistic effect enables the full penetration of electrolyte on the anode surface during discharge, greatly improving the electrochemical activity of the anode.

[0063] (4) Morphological analysis of corrosion products Figure 10 Demonstrated the performance of Mg-Hg-Ga alloys at 1-20 mA·cm 2Surface morphology after discharge at low current density and removal of corrosion products. Results showed that all sample surfaces exhibited micropores formed by the escape of hydrogen bubbles, but no large pores or voids were observed, indicating no significant blocky effect. At low current densities (1-10 mA·cm⁻¹), the surface morphology was further improved. 2 Under these conditions, the surface exhibits a composite structure with both pitted and flat areas. The pitted areas are rough internally, while the flat areas have a smooth surface. When the current density increases to 15-20 mA·cm⁻¹, the surface becomes more porous. 2 At this point, the pitting disappears, and the entire surface transforms into a relatively flat morphology with moderate roughness. Analysis shows that the pitting and rough regions at high current densities correspond to highly reactive fine-grained regions. These regions provide numerous active sites to promote electrochemical reactions, but also lead to intensified localized corrosion and severe hydrogen evolution, affecting anode efficiency. The flat regions present at all current densities correspond to grain growth regions, which, as a structural framework, maintain electrode morphology stability and effectively prevent excessive corrosion and pulverization of the material. This "reaction point-structural plane" microstructure gives the Mg-Hg-Ga alloy both high electrochemical activity and excellent structural stability, providing an effective microstructure solution for achieving efficient and durable magnesium-based anodes.

[0064] (5) Analysis of electrode interface structure after discharge Figure 11 Example 1 demonstrates the Mg-Hg-Ga alloy at 5 mA·cm⁻¹ 2 The cross-sectional morphology after 2 hours of discharge at the specified current density was analyzed. The results show that an extremely thin layer of corrosion products formed on the surface of the Mg-Hg-Ga alloy, confirming its self-exfoliation characteristic. Furthermore, no alloy particles coated with corrosion products were observed in the cross-sectional morphology, indicating that no significant block effect occurred during discharge. This structure contributes to the Mg-Hg-Ga alloy material achieving both high discharge activity and anolyte utilization efficiency.

[0065] In summary, this invention provides a Mg-Hg-Ga anode material for high-power magnesium-air batteries, its preparation method, and its application. By optimizing the alloy composition and microstructure, this material achieves high discharge activity while also possessing good anode utilization efficiency and structural stability. It effectively alleviates common problems in existing magnesium alloy anode materials, such as severe hydrogen evolution corrosion, discharge product accumulation, and block effect, providing reliable technical support for the performance optimization and widespread application of magnesium-air batteries. The beneficial effects of this invention are described in detail below from several aspects: 1. Excellent discharge activity: This invention effectively avoids the formation of coarse second phases and their adverse effects on electrochemical performance by introducing Hg and Ga alloying elements and ensuring their complete and uniform solid solution in a magnesium matrix. Simultaneously, a single-peak microstructure with fine grains and grain growth regions was obtained through plastic deformation and heat treatment. This structure introduces numerous high-energy grain boundaries, providing abundant active sites for the discharge reaction. Based on this, the material exhibits "point" characteristics induced by the dissolution-redeposition behavior of Hg and Ga and the heterogeneous composite structure. The "surface-cooperative" corrosion mechanism enables continuous renewal of the active surface, thereby significantly improving discharge activity. Experiments show that at 1 mA·cm⁻¹, 2 5mA·cm 2 10mA·cm 2 15mA·cm 2 and 20mA·cm 2 At a given current density, the discharge voltage of the anode material of this invention is 1.31-1.86V, and the specific energy is 1182 kJ / m³. 1930mWh·g 1 Both are significantly superior to traditional magnesium alloy anode materials.

[0066] 2. High anode utilization efficiency: This invention utilizes the inherently high hydrogen evolution overpotentials of Hg and Ga elements, combined with a heterogeneous composite structure design, to effectively suppress hydrogen evolution corrosion. The relatively low grain boundary density in the grain growth regions reduces the active sites for the hydrogen evolution reaction, thereby lowering the overall hydrogen evolution reaction rate of the material. This is beneficial for maintaining a high anodic utilization efficiency. Experiments show that the anodic utilization efficiency of the anodic material of this invention reaches 51.3-63.9% at different current densities, comparable to existing high-performance magnesium alloy anodic materials.

[0067] 3. Good discharge stability: The anode material of this invention effectively balances electrochemical activity and structural stability through a heterogeneous composite structure. This is especially true at high current densities (e.g., 15, 20 mA·cm⁻¹). -2Under these conditions, the material can achieve uniform discharge. At low current densities, differences in electrochemical activity within the microstructure induce localized pitting corrosion, but due to the low driving force of the reaction, this corrosion morphology is unlikely to develop into structural damage. At high current densities, due to the unimodal grain distribution characteristic of the microstructure, the average grain size of the fine-grained region and the grain-growing region are similar, and the activity difference between them is limited. Under the action of high driving force of the reaction, synchronous activation is easily achieved, thus forming a uniform and flat corrosion morphology. At the same time, the grain-growing region, as a structural framework, effectively inhibits the hydrogen evolution reaction with its relatively mild electrochemical reactivity, slowing down the microstructural damage caused by gas escape, thereby delaying the pulverization process of the material. This structure helps maintain the morphological stability and structural durability of the electrode under high-power discharge conditions, making it suitable for high-power, long-life magnesium-air battery systems.

[0068] Finally, it should be noted that the above embodiments 1 are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments 1, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments 1, or make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments 1 of the present invention.

Claims

1. A Mg-Hg-Ga anode material for high-power magnesium-air batteries, characterized in that, The anode material comprises, by weight percentage, 0.06-0.10 wt.% Hg, 1.55-1.75 wt.% Ga, with the remainder being Mg and unavoidable impurities. The microstructure of the anode material is a single solid solution structure with uniform distribution of alloying elements and no second phase precipitation. It is a heterogeneous composite microstructure composed of grain refinement region and grain growth region. The overall grain size exhibits a continuous single-peak distribution with sharp peaks and a slightly wide distribution, without any separated double or multi-peak phenomena.

2. The Mg-Hg-Ga anode material for high-power magnesium-air batteries according to claim 1, characterized in that, The content of the unavoidable impurities shall satisfy the following: Fe≤0.016%, Ca≤0.0023%, Mn≤0.0023%, Si≤0.0020%, Cu≤0.0002%, Ni≤0.0004%.

3. The Mg-Hg-Ga anode material for high-power magnesium-air batteries according to claim 1, characterized in that, The anode material has an average grain size of 15-25 μm and a strong basal texture, with the maximum strength of the (0001) surface texture being greater than or equal to 11.

5.

4. A method for preparing the Mg-Hg-Ga anode material for a high-power magnesium-air battery as described in claim 1, 2, or 3, characterized in that, Includes the following steps: S1. Using magnesium matrix raw materials, Ga raw materials and Mg-15Hg (weight percentage) master alloy as raw materials, calculate and weigh each raw material according to the target composition; S2. Polish all raw materials to remove oxide scale; S3. Place the magnesium matrix raw material in a crucible and melt it at 720°C under a protective atmosphere. After it is completely melted, add the Mg-15Hg master alloy and Ga raw material in sequence, stir for 30 minutes and then remove the slag. S4. The refined melt is cast into an ingot at 720℃ using a water-cooled copper mold, with the cooling rate controlled at 50℃ / s. S5. Keep the ingot at 355-365℃ for 8 hours; S6. After solution treatment, directly heat to 395-405℃ and keep warm for 4 hours; S7. Slowly cool to 350°C at a rate of 50°C / h; S8. After holding at 350℃ for 30 minutes, transfer to an extrusion die preheated to 350℃, with a total transfer time of ≤3 minutes; S9. Under the condition that the temperature of the mold, extrusion device and billet are all 350℃, hot extrusion is carried out at an extrusion speed of 1m / min to obtain a sheet. S10. The extruded sheet is subjected to low-temperature stabilization and pulse excitation treatment in sequence, and finally water quenched to room temperature to obtain Mg-Hg-Ga anode material for high-power magnesium-air batteries.

5. The method for preparing Mg-Hg-Ga anode material for high-power magnesium-air batteries according to claim 4, characterized in that, In step S1, magnesium ingots with a purity ≥ 99.99 wt.%, gallium with a purity ≥ 99.99 wt.%, and Mg-15Hg master alloy are used as raw materials and weighed according to the target composition.

6. The method for preparing Mg-Hg-Ga anode material for high-power magnesium-air batteries according to claim 4, characterized in that, In step S3, the protective atmosphere is argon.

7. The method for preparing Mg-Hg-Ga anode material for high-power magnesium-air batteries according to claim 4, characterized in that, In step S4, the casting process maintains an argon protective atmosphere, and the diameter of the ingot is 95 mm.

8. The method for preparing Mg-Hg-Ga anode material for high-power magnesium-air batteries according to claim 4, characterized in that, In step S9, the hot extrusion ratio is 44:1; the width of the sheet is 80mm and the thickness is 2mm.

9. The method for preparing Mg-Hg-Ga anode material for high-power magnesium-air batteries according to claim 4, characterized in that, Step S10 specifically includes: a. Low-temperature stabilization: The extruded sheet was left to stand at 305℃ for 40 seconds; b. Pulse excitation treatment: The plate material that has been stabilized at low temperature is quickly transferred to an environment of 385-395℃ and subjected to instantaneous heat treatment for 8 seconds; c. Water quenching: The plate after pulse excitation treatment is quickly water quenched to room temperature.

10. The application of the Mg-Hg-Ga anode material for high-power magnesium-air batteries according to claim 1 in magnesium-air batteries.

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