An In-Sn-Bi ternary eutectic alloy anode material, its preparation method and application

Abstract

The present invention discloses a negative electrode material of In-Sn-Bi ternary eutectic alloy. The ternary eutectic alloy negative electrode material comprises three elements of In, Sn and Bi, and the molar ratio of In to Sn is (1-2):1, and the Bi content is greater than 25%. The present invention also discloses a preparation method and an application of the In-Sn-Bi ternary eutectic alloy negative electrode material. The In-Sn-Bi ternary eutectic alloy negative electrode material provided by the present invention, by adopting a combination of In element and Sn element with a specific molar ratio, and at the same time combining with Bi which has good kinetics but is easy to decay, the three form a eutectic structure with a fine nanoscale structure during the ball milling alloying process, significantly increasing the specific surface area of the active material and the stability of the structure. The formed hexagonal Bi phase, tetragonal Sn phase and tetragonal InBi phase improve the specific capacity of the magnesium battery and have excellent cycle stability. The alloy negative electrode material prepared from the In-Sn-Bi ternary eutectic alloy negative electrode material has extremely small screening after 80 cycles, and the capacity retention rate is as high as 98%.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical materials, and particularly relates to an In-Sn-Bi ternary eutectic alloy anode material, a preparation method thereof, and an application thereof. Background Art

[0002] The deficiencies of traditional energy in terms of environmental protection, cost, and sustainability are becoming increasingly prominent. Renewable clean energy is an inevitable trend for future development. Among existing chemical power source technologies, lithium-ion batteries are widely used in electric vehicles, electronic devices, and grid energy storage fields. However, lithium-ion batteries still struggle to meet the growing demands for safety and energy density, and the available lithium reserves in the earth's crust are limited. There is still a lack of economically effective lithium recovery technologies, and the continuous consumption of lithium resources will inevitably lead to an increase in the cost of lithium-ion batteries. Therefore, there is an urgent need to develop new green secondary batteries with high specific energy, high safety, and low cost.

[0003] The magnesium reserve in the earth's crust (2.9 wt%) is much higher than that of lithium (0.002 wt%). It is a low-cost material, and the melting point of magnesium is 660 °C, which is more stable than lithium in the atmosphere and easier to handle. The redox potential of magnesium is low (-2.37 V vs. H + / H2), and the theoretical volume capacity of metallic magnesium is 3833 mAh / cm 3 which is nearly twice that of lithium-ion batteries. This is because one redox center of magnesium carries two charges, thus having a higher capacity storage ability within the same volume. And the magnesium ion radius is similar to that of lithium ions and the expansion caused by replacing two lithium ions with one magnesium ion inserted into the host lattice will also be reduced. Different from the easy formation of dendrites by lithium metal, alkaline earth metal ions have a lower diffusion energy and weaker bond binding, so it is easier to form a smooth deposition layer, making magnesium-ion batteries safer. Therefore, rechargeable magnesium batteries with metallic magnesium as the anode have potential advantages in terms of cost, energy density, and safety. They are considered to be a very promising green secondary battery and have become an important research and development direction for new rechargeable batteries. However, the incompatibility between the cathode, electrolyte, and anode is one of the main obstacles to the development of rechargeable magnesium batteries. Metallic magnesium is prone to form a passivation film on the surface in traditional simple electrolytes, making it difficult for magnesium ions to deposit / dissolve reversibly, which limits the development of rechargeable magnesium batteries. Finding a substitute anode with good compatibility is one of the important solutions.

[0004] In recent years, although substitute anodes for rechargeable magnesium batteries have been widely concerned and studied, there is currently no anode material with high cycle stability, and various developed substitute anodes for rechargeable magnesium batteries generally still have problems such as high production cost and complex preparation process, which are not suitable for large-scale production and seriously hinder their commercial application process. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this purpose, the main object of the present invention is to provide an In-Sn-Bi ternary eutectic alloy negative electrode material with high negative electrode capacity, simple preparation process and low cost. The present invention also discloses a preparation method and application of the In-Sn-Bi ternary eutectic alloy negative electrode material.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] In a first aspect, an In-Sn-Bi ternary eutectic alloy negative electrode material, the ternary eutectic alloy negative electrode material includes three elements of In, Sn and Bi, and the molar ratio of In to Sn is (1-2):1, and the Bi content is greater than 25%.

[0008] Preferably, the molar ratio of In to Sn is 1, and the Bi content is 80%.

[0009] Preferably, the crystal phase of the In-Sn-Bi ternary eutectic alloy negative electrode material at least includes an In-Sn eutectic structure, a Bi phase in a hexagonal crystal system, a Sn phase in a tetragonal crystal system and an InBi phase in a tetragonal crystal system.

[0010] In a second aspect, a preparation method of the foregoing In-Sn-Bi ternary eutectic alloy negative electrode material, including the following steps: According to the formula requirements, weigh indium powder, tin powder and bismuth powder, put them into a ball milling tank made of polytetrafluoroethylene under an inert atmosphere, put grinding balls according to a ball / material ratio of (10-20):1, and ball mill in a planetary ball mill for 60-80 h to obtain an indium-tin-bismuth ternary eutectic alloy negative electrode active material.

[0011] Preferably, the grinding balls are agate grinding balls.

[0012] Preferably, the inert atmosphere is argon or nitrogen.

[0013] In a third aspect, an application of the foregoing In-Sn-Bi ternary eutectic alloy negative electrode material, the In-Sn-Bi ternary eutectic alloy negative electrode material is used to prepare a negative electrode active material of a secondary battery.

[0014] Preferably, the secondary battery is a magnesium ion battery.

[0015] In a fourth aspect, a magnesium ion battery negative electrode material includes a negative electrode conductive agent, a negative electrode binder and the foregoing In-Sn-Bi ternary eutectic alloy negative electrode material.

[0016] Further, the negative electrode conductive agent is one of acetylene black, carbon black, natural graphite, artificial graphite, Ketjen black, carbon fiber, copper, aluminum, silver, nickel, etc., or a mixture of any two or more thereof; the negative electrode binder is one of polyvinylidene fluoride, polytrifluorochloroethylene, polyvinyl fluoride PVF, polyvinyl alcohol, or a mixture of any two or more thereof.

[0017] Compared with the prior art, the present invention has at least the following advantages:

[0018] 1) The In-Sn-Bi ternary eutectic alloy negative electrode material provided by the present invention, by alloying with a combination of In element and Sn element with a specific molar ratio, and at the same time combining with Bi which has good kinetics but is easy to decay, the three form a fine nano-structured eutectic structure during the ball milling alloying process, significantly increasing the specific surface area of the active material and the stability of the structure, and the formed hexagonal Bi phase, tetragonal Sn phase and tetragonal InBi phase improve the specific capacity of the magnesium battery and have excellent cycle stability.

[0019] 2) The In-Sn-Bi ternary eutectic alloy negative electrode material provided by the present invention, by changing the molar ratio of In-Sn, with the changes of In component, Sn component and Bi component, using the mechanically alloyed In-Sn-Bi ternary eutectic alloy as the negative electrode material of the rechargeable magnesium battery, has a high theoretical capacity and experimental capacity, and some components maintain good cycle reversibility and stability. In particular, the prepared alloy negative electrode material has extremely small screening after 80 cycles, and the capacity retention rate is as high as 98%. The excellent cycle stability ensures the long-life use of the battery material. In addition, this alloy series also has good rate performance, kinetic and thermodynamic properties, which has important practical significance for the commercial application of rechargeable magnesium batteries.

[0020] 3) The preparation method of the In-Sn-Bi ternary eutectic alloy negative electrode material provided by the present invention is simple, the raw materials are environmentally friendly, the preparation cost is low, and it is easy to realize large-scale and process production; the prepared In-Sn-Bi ternary eutectic alloy material has good electrochemical activity and is suitable as the negative electrode material of the rechargeable magnesium battery. Description of the Drawings

[0021] In order to more clearly illustrate the specific embodiments of the present invention, the following will briefly introduce the drawings required for the specific embodiments or the description of the prior art.

[0022] Figure 1 For the In 10 Sn 10 Bi 80 Microscopic morphology diagram of the powder alloy.

[0023] Figure 2 The micrograph of the In 40 Sn 20 Bi 40 powder alloy prepared by the present invention.

[0024] Figure 3 The micrograph of the In 50 Sn 25 Bi 25 powder alloy prepared by the present invention.

[0025] Figure 4 The backscattered electron image, transmission image and surface scan image of the In 10 Sn 10 Bi 80 powder alloy prepared by the present invention.

[0026] Figure 5 The X-ray diffraction patterns of the In 10 Sn 10 Bi 80 、In 40 Sn 20 Bi 40 and In 50 Sn 25 Bi 25 alloys.

[0027] Figure 6 The charge / discharge curves of the In 10 Sn 10 Bi 80 、In 40 Sn 20 Bi 40 and In 50 Sn 25 Bi 25 alloy electrodes at a rate of 0.02C.

[0028] Figure 7 The cycling performance curves of the In 10 Sn 10 Bi 80 、In 40 Sn 20 Bi 40 、In 50 Sn 25 Bi 25 and In 10 Sn 80 Bi 10 alloy electrodes and the metal In, Sn and Bi electrodes at a rate of 0.02C.

[0029] Figure 8For the In 10 Sn 10 Bi 80 、In 40 Sn 20 Bi 40 and In 50 Sn 25 Bi 25 alloy electrodes at 0.02C, 0.05C, 0.1C, and 0.33C rate performance graphs.

[0030] Figure 9 For the theoretical specific capacities of the electrodes prepared in Examples 1 to 3 and Comparative Examples 2 to 4 and the experimental reversible specific capacities at 0.02C rate for 80 cycles.

[0031] Figure 10 For the In and Sn in Example 1 with the best performance, where the ratio of In to Sn is 1:1 and both are 10% 10 Sn 10 Bi 80 At a rate of 0.02C, the actual specific capacity and its retention rate at 50 cycles and 80 cycles, respectively. Detailed implementation mode

[0032] The present invention will be further described in detail below in conjunction with the drawings and examples. The following examples are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby.

[0033] When a quantity, concentration, or other value or parameter is expressed in the form of a range, a preferred range, or a preferred upper and lower limit of a value, it should be understood that any range formed by combining any upper limit of the range or preferred value with any lower limit of the range or preferred value is specifically disclosed, regardless of whether the range is specifically disclosed. Unless otherwise indicated, the numerical range values listed herein include the endpoints of the range and all integers and fractions within the range.

[0034] Unless otherwise specified, all percentages, parts, ratios, etc. in this article are by weight.

[0035] The materials, methods, and examples in this article are all exemplary and should not be construed as restrictive unless otherwise specified.

[0036] Unless otherwise indicated, the professional and scientific terms used in this article have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention. The experimental methods without specific conditions noted in the examples are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0037] Example 1

[0038] The In-Sn-Bi ternary eutectic alloy anode material provided by the present invention is obtained through the following preparation method. Specifically:

[0039] Weigh 0.181 g of indium powder with a purity of 99.99%, 0.187 g of tin powder with a purity of 99.99%, and 2.632 g of bismuth powder with a purity of 99.9%. The molar ratio of In to Sn is 1:1. Mix them evenly and put them into a polytetrafluoroethylene ball milling tank under an argon atmosphere. Put agate grinding balls in according to a ball-to-material ratio of 20:1, and ball mill in a planetary ball mill for more than 60 - 80 h to collect the In 10 Sn 10 Bi 80 alloy powder, where the element subscript represents the molecular value of the molar fraction of the element in the three-element composition. For example, in In 10 Sn 10 Bi 80 by molar fraction, In accounts for 10%, Sn accounts for 10%, and Bi accounts for 80%, and the same applies hereinafter.

[0040] Perform scanning electron microscopy and X-ray diffraction on the In-Sn-Bi ternary eutectic alloy anode material prepared in this example. The results are as shown in Figure 1 、 Figure 4 and Figure 5 : Among them Figure 1 is the scanning electron microscopy photograph of the prepared In 10 Sn 10 Bi 80 alloy powder. As can be seen from Figure 1 , the material is composed of particles with a size of 10 - 30 μm; Figure 4 is the backscattered electron image and high-resolution transmission electron microscopy image of the prepared In 10 Sn 10 Bi 80 alloy powder. As can be seen from Figure 4 、 Figure 5 , it is composed of uniformly distributed fine Bi phase with a hexagonal crystal system, Sn phase with a tetragonal crystal system, and InBi phase with a tetragonal crystal system, forming a fine and uniform eutectic microstructure, and its particle structure has reached the nanoscale.

[0041] Prepare an electrode with the In-Sn-Bi ternary eutectic alloy anode material prepared in this example, assemble a half-cell and conduct performance tests. Specifically:

[0042] Put the In prepared in this example 10 Sn 10 Bi 80The alloy powder is mixed with acetylene black, polyvinylidene fluoride, and carbon nanofibers in a mass ratio of 7:1:1:1. N-methylpyrrolidone is used as a solvent to prepare a slurry, which is then coated on a copper foil to make an electrode sheet as the negative electrode. The solvent N-methylpyrrolidone is dried at room temperature for 12 h, and then transferred to a vacuum drying oven and dried at 60 °C for 12 h. Then, it is stamped into electrode discs with a diameter of 12 mm and stored in a glove box filled with high-purity argon for standby. The active material loading of the electrode sheet is 2-3 mg / cm 2 , using 0.4 M (MgPhCl)2-AlCl3 as the electrolyte, glass fiber (GF / D) as the separator, and a magnesium sheet as the counter electrode and reference electrode, and assembling it into a CR2032 coin cell in a glove box filled with argon. The encapsulated battery is charged / discharged at a current density of 0.026 mA / cm 2 , with a cut-off voltage of 0.005-0.8 V, and the cycle performance is tested at a current density of 0.026 mA / cm 2 .

[0043] Among them, In 10 Sn 10 Bi 80 The alloy powder can be mixed with acetylene black and polyvinylidene fluoride within the mass ratio range of 7-8:1-2:1. In this example, In 10 Sn 10 Bi 80 The alloy powder is mixed with acetylene black and polyvinylidene fluoride in a mass ratio of 8:2:1.

[0044] Test results: There is an activation process in the charge / discharge test of the prepared In 10 Sn 10 Bi 80 alloy electrode at a current density of 0.026 mA / cm 2 as shown; and the reversible charge / discharge performance after activation is as Figure 7 shown. The reversible discharge capacity is 263.7 mAh / g, and the reversible charge capacity is 254 mAh / g, showing high capacitance performance. The In Figure 6 prepared in this example 10 Sn 10 Bi 80 The cycle performance of the alloy electrode is as Figure 7 shown. At a current density of 0.026 mA / cm 2 , it still has a high specific capacity of 264 mAh / g. After 80 cycles, the capacity can reach 259 mAh / g.

[0045] The In, Sn, and Bi ternary eutectic alloy negative electrode material provided by the present invention enables magnesium ion batteries to have a high theoretical capacity and experimental capacity, good cycle stability, and magnesium ion batteries prepared with it as the negative electrode material have more excellent electrochemical performance. When preparing the In, Sn, and Bi ternary eutectic alloy negative electrode active material into an electrode sheet, the conductive agent is a material to ensure good charge and discharge performance of the electrode, including but not limited to acetylene black, carbon black, natural graphite, artificial graphite, Ketjen black, carbon fiber, copper, aluminum, silver, nickel, etc.; polyvinylidene fluoride is used as the binder to ensure better bonding strength between the active substances and between the active substances and the current collector during the use of the negative electrode, including but not limited to one or more of polyvinylidene fluoride, polytrifluorochloroethylene, polyvinyl fluoride PVF, and polyvinyl alcohol; copper foil is used as the negative electrode current collector, and the main function of the current collector is to collect the current generated by the battery active substances so as to form a larger current for external output, and it can be selected from one or more composite materials of aluminum, copper, lead, iron, tin, cadmium, zinc, manganese, antimony, nickel, gold, titanium, etc.

[0046] Example 2

[0047] An In-Sn-Bi ternary eutectic alloy negative electrode material provided by the present invention is obtained through the following preparation method. Specifically:

[0048] Weigh 0.899 g of indium powder with a purity of 99.99%, weigh 0.465 g of tin powder with a purity of 99.99%, and 1.636 g of bismuth powder with a purity of 99.9%. The molar ratio of In to Sn is 2:1. Mix them evenly and put them into a polytetrafluoroethylene ball milling tank under an argon atmosphere. Put agate grinding balls according to a ball-to-material ratio of 20:1, and ball mill in a planetary ball mill for 60 - 80 h to collect the In 40 Sn 20 Bi 40 alloy powder.

[0049] Perform scanning electron microscopy and X-ray diffraction on the In-Sn-Bi ternary eutectic alloy negative electrode material prepared in this example. The results are as Figure 2 and Figure 5 shown: Among them Figure 2 is the scanning electron microscopy photograph of the In 40 Sn 20 Bi 40 alloy powder prepared in this example. As can be seen from Figure 2 the In-Sn-Bi ternary eutectic alloy negative electrode material is composed of flake particles with a length of 20 μm, a width of 40 μm, and a thickness of 5 μm; Figure 5 is the X-ray diffraction pattern of the In 40 Sn 20 Bi 40 alloy powder. From Figure 5It can be seen that the In-Sn-Bi ternary eutectic alloy negative electrode material is composed of a Bi phase with a hexagonal crystal system, a Sn phase with a tetragonal crystal system, an InBi phase with a tetragonal crystal system, and Bi3In5.

[0050] The method for assembling the half-cell and testing the performance is the same as that in Example 1. The In in this example 40 Sn 20 Bi 40 The reversible charge / discharge results after activation of the alloy electrode are as Figure 6 shown. The reversible discharge capacity is 239 mAh / g, and the reversible charge capacity is 222.2 mAh / g. It shows high electrochemical activity and magnesium storage performance at a current density of 0.03 mA / cm 2 ; at the same time, the cycling performance of the In 40 Sn 20 Bi 40 alloy electrode is as Figure 7 shown. At a current density of 0.03 mA / cm 2 , the initial reversible capacity is 239 mAh / g, and the capacity is 124.5 mAh / g after 80 cycles.

[0051] Example 3

[0052] The In-Sn-Bi ternary eutectic alloy negative electrode material provided by the present invention is obtained through the following preparation method. Specifically:

[0053] Weigh 1.236 g of indium powder with a purity of 99.99%, weigh 0.639 g of tin powder with a purity of 99.99%, and 1.125 g of bismuth powder with a purity of 99.9%. The molar ratio of In to Sn is 2:1. Mix them evenly and put them into a polytetrafluoroethylene ball milling tank under an argon atmosphere. Put agate grinding balls according to a ball-to-material ratio of 20:1, and ball mill in a planetary ball mill for 60 - 80 h to collect the In 50 Sn 25 Bi 25 alloy powder.

[0054] Perform scanning electron microscopy and X-ray diffraction on the In-Sn-Bi ternary eutectic alloy negative electrode material prepared in this example. The results are as Figure 3 and Figure 5 shown: Among them Figure 3 is the scanning electron microscopy photograph of the prepared In 50 Sn 25 Bi 25 alloy powder. It can be seen from Figure 3 that the material is composed of particles with a size of 20 - 50 μm. Figure 5 is for In 50 Sn 25 Bi 25X-ray diffraction pattern of the alloy powder, as shown in Figure 5 It can be seen that the In-Sn-Bi ternary eutectic alloy negative electrode material is composed of a Bi phase with a hexagonal crystal system, a Sn phase with a tetragonal crystal system, and an InBi phase with a tetragonal crystal system.

[0055] The method for assembling the half-cell and testing the performance is the same as that in Example 1. The In in this example 50 Sn 25 Bi 25 The reversible charge / discharge results after the alloy electrode is activated are as shown in Figure 6 The reversible discharge capacity is 172.3 mAh / g, and the reversible charge capacity is 161.4 mAh / g. The In 50 Sn 25 Bi 25 The cycle performance of the alloy electrode is as shown in Figure 7 At a current density of 0.05 mA / cm 2 The reversible capacity is 172.3 mAh / g, showing excellent electrochemical behavior. After 80 cycles, the capacity is 94 mAh / g.

[0056] Comparative Example 1

[0057] For the In-Sn-Bi ternary alloy negative electrode material in this comparative example, its formulation and ratio are basically the same as those in Example 2, except that the molar ratio of In to Sn is 1:8. Its preparation method is the same as that in Example 2, and finally, the In 10 Sn 80 Bi 10 alloy is obtained.

[0058] Comparative Example 2

[0059] For the negative electrode material in this comparative example, its formulation and ratio are basically the same as those in Example 2, except that its formulation only contains bismuth powder with a purity of 99.99%; its preparation method is the same as that in Example 2, and finally, micron-sized Bi powder is obtained.

[0060] Comparative Example 3

[0061] For the negative electrode material in this comparative example, its formulation and ratio are basically the same as those in Example 2, except that its formulation only contains tin powder with a purity of 99.99%; its preparation method is the same as that in Example 2, and finally, micron-sized Sn powder is obtained.

[0062] Comparative Example 4

[0063] For the negative electrode material in this comparative example, its formulation and ratio are basically the same as those in Example 2, except that its formulation only contains indium powder with a purity of 99.99%; its preparation method is the same as that in Example 2, and finally, micron-sized In powder is obtained.

[0064] The test results of the cycling performance of the negative electrode material prepared in Comparative Example 1 at a rate of 0.02C are as follows Figure 7 shown. When In and Sn are in a molar ratio of 1:8, the cycling performance is very poor because a fine ternary eutectic structure cannot be formed at a large molar ratio of In and Sn. For the negative electrode materials prepared in Example 1, Example 2, and Example 3, charge-discharge tests were carried out at rates of 0.02C, 0.05C, 0.1C, and 0.33C respectively, and the test results are as follows Figure 8 shown. When In and Sn are in a molar ratio of 1:1 and the atomic proportion of Bi is 80%, the rate performance is the best. When the proportions of In and Sn are increased simultaneously, the rate performance does not improve and decreases. Therefore, based on the In-Sn-Bi ternary alloy phase diagram, comparing Example 1, Example 2, and Example 3, increasing the proportions of In and Sn simultaneously may form a certain In-Sn eutectic structure but cannot combine with Bi to form a fine ternary eutectic structure at the same time, and will reduce the Bi content that provides most of the specific capacity, resulting in a decrease in electrochemical performance.

[0065] For the negative electrode materials prepared in Comparative Examples 2, 3, and 4, the method for assembling and testing the performance of the half-cell was the same as that in Example 1, and the results are as follows Figure 9 shown. From Figure 9 it can be seen that micron-sized In and Sn electrodes cannot provide capacity, and the capacity of the Bi electrode is limited by its own theoretical capacity (385 mAh / g) and cannot be further improved. The experimental capacities of the In 10 Sn 10 Bi 80 , In 40 Sn 20 Bi 40 and In 50 Sn 25 Bi 25 electrodes are all significantly higher than those of In, Sn, and Bi electrodes.

[0066] Figure 10 For the In and Sn with the optimal performance in Example 1, with a ratio of 1:1 and both being 10% of In 10 Sn 10 Bi 80 at a rate of 0.02C, the actual specific capacity and its retention rate at 50 cycles and 80 cycles respectively. From Figure 10 it can be seen that the In 10 Sn 10 Bi 80 ternary eutectic alloy negative electrode material in this application has excellent specific capacity and capacity retention rate.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention, and they should all be covered within the scope of the claims and the description of the present invention.

Claims

1. A negative electrode material for a magnesium ion battery, characterized in that, The negative electrode material includes an In-Sn-Bi ternary eutectic alloy negative electrode material, and the molar ratio of In to Sn is (1-2):1, the Bi content is greater than 25%, and the crystal phases formed by the In-Sn-Bi ternary eutectic alloy negative electrode material at least include a Bi phase in the hexagonal crystal system, a Sn phase in the tetragonal crystal system, and an InBi phase in the tetragonal crystal system.

2. The anode material for a magnesium ion battery according to claim 1, characterized in that, The molar ratio of In to Sn is 1, and the Bi content is 80%.

3. The negative electrode material of a magnesium ion battery according to claim 1 or 2, wherein the In-Sn-Bi ternary eutectic alloy negative electrode material is obtained by the following method: According to the formula requirements, weigh indium powder, tin powder, and bismuth powder, put them into a ball milling tank made of polytetrafluoroethylene under an inert atmosphere, put grinding balls according to a ball / material ratio of (10-20):1, and ball mill in a planetary ball mill for 60-80 h to obtain an indium-tin-bismuth ternary eutectic alloy negative electrode active material.

4. The negative electrode material of the magnesium ion battery according to claim 3, characterized in that, The grinding balls are agate grinding balls.

5. The negative electrode material of the magnesium ion battery according to claim 4, characterized in that, The inert atmosphere is argon or nitrogen.

6. The negative electrode material for a magnesium ion battery according to claim 1, wherein It also includes a negative electrode conductive agent and a negative electrode binder.

7. The negative electrode material of the magnesium ion battery according to claim 6, characterized in that The negative electrode conductive agent is one of acetylene black, carbon black, natural graphite, artificial graphite, Ketjen black, carbon fiber, copper, aluminum, silver, nickel, etc. or a mixture of any two or more of them; the negative electrode binder is one of polyvinylidene fluoride, polychlorotrifluoroethylene, polyvinyl fluoride PVF, polyvinyl alcohol or a mixture of any two or more of them.

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