Rare earth silicon alloy material, preparation method thereof and application of rare earth silicon alloy material in lithium battery

Abstract

The invention discloses a preparation method of a rare earth silicon alloy material, which comprises the following steps: S1, uniformly mixing a rare earth compound with silicon powder to obtain a precursor; s2, mixing the precursor obtained in the step S1 with a reducing agent, and performing high-temperature treatment on the mixture to obtain an impurity-containing rare earth silicon alloy; and S3, the impurity-containing rare earth silicon alloy obtained in the step S2 is washed away with a solvent, and the rare earth silicon alloy material is obtained. Wherein the atom molar ratio of the rare earth to the silicon is (1-50): (50-99). The rare earth silicon alloy material is prepared by a reduction method and is applied to the lithium battery as a negative electrode, so that the volume change of the silicon negative electrode can be inhibited to a certain extent, the conductivity of the negative electrode is improved, and the cycling stability of the battery is improved.

Description

Technical Field

[0001] The present invention relates to a rare earth silicon alloy material, a preparation method thereof and application in a lithium battery, belonging to the technical field of lithium batteries. Background Art

[0002] To achieve the goals of "carbon peak and carbon neutrality," my country is strongly supporting green and low-carbon industries such as wind / solar power generation and new energy vehicles. The development of these new energy industries requires safe, stable, and high-energy-density energy storage devices. Among these energy storage systems, lithium batteries, with their long cycle life and high energy density, are widely used.

[0003] Lithium batteries typically consist of three parts: a negative electrode, an electrolyte, and a positive electrode. The properties of the negative electrode affect the performance of the battery. For lithium batteries, silicon negative electrodes have a low lithium insertion potential and a high theoretical capacity, enabling lithium batteries to achieve a high energy density and have been successfully applied in lithium batteries. However, during the cycling of lithium batteries, silicon negative electrode particles undergo significant volume changes, leading to problems such as solid-solid contact failure and silicon particle pulverization and shedding, which is not conducive to the diffusion of electrons and ions within the electrode, thereby reducing the cycling performance of lithium batteries.

[0004] In response to the above problems, this application is filed. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a rare earth silicon alloy material and a preparation method thereof, and to apply it in lithium batteries to solve the problem of poor cycle stability of lithium battery silicon negative electrodes.

[0006] The first object of the present invention is to provide a method for preparing a rare earth silicon alloy material, comprising the following steps:

[0007] S1: Mixing rare earth compound and silicon powder uniformly to obtain a precursor;

[0008] S2: mixing the precursor obtained in step S1 with a reducing agent, and subjecting the mixture to a high-temperature treatment to obtain a rare earth silicon alloy containing impurities;

[0009] S3: washing the rare earth silicon alloy containing impurities obtained in step S2 with a solvent to remove impurities, thereby obtaining a rare earth silicon alloy material.

[0010] The atomic molar ratio of rare earth to silicon is 1-50:50-99.

[0011] Preferably, the atomic molar ratio of rare earth to silicon is 1-4:16-19.

[0012] Preferably, the rare earth is a combination of one or more elements selected from scandium, yttrium, lanthanum, cerium, chromium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium; the rare earth compound includes a combination of one or more elements selected from rare earth oxides, rare earth chlorides, rare earth bromides, rare earth iodides, and rare earth sulfides; the silicon powder is a micron-sized or nanometer-sized silicon element powder; and the reducing agent is a combination of one or more elements selected from lithium, sodium, magnesium, calcium, and carbon.

[0013] Using the above technical solution, the particle size of micron-sized silicon powder is 1-10 μm, preferably 4-6 μm, and the particle size of nano-sized silicon powder is 20-200 nm, preferably 50-100 nm. The reducing agent is in the form of a block, flake, powder, or a combination of one or more of the following:

[0014] Preferably, the method of mixing the rare earth compound and silicon powder in step S1 is a combination of one or more of a manual grinding method, a ball milling method, and a liquid phase method.

[0015] Using the above technical solution, the manual grinding method is to mix the rare earth compound and silicon powder in a mortar, and the grinding time is 5-30 minutes; the mechanical ball milling method is to use a ball mill to mix the rare earth compound and silicon powder, the ball milling speed is 200-500r / min, and the ball milling time is 1-10h; the liquid phase method is to dissolve the rare earth compound in a solvent, add silicon powder, heat and stir, evaporate the solvent, and then vacuum heat and dry for 5-10h.

[0016] Preferably, the method of mixing the precursor and the reducing agent in step S2 is a combination of one or more of manual grinding, ball milling, and melting, and the high-temperature treatment is a combination of one or more of electromagnetic induction heating, muffle furnace heating, and Joule ultrafast heating.

[0017] Using the above technical solution, the manual grinding method is to mix the precursor and the reducing agent in a mortar, and the grinding time is 5-30 minutes; the mechanical ball milling method is to use a ball mill to mix the precursor and the reducing agent, the ball milling speed is 200-500r / min, and the ball milling time is 1-10h; the melting method is to mix the precursor and the reducing agent, press them into tablets, and react the molten reducing agent with the precursor through a heating process, the heating temperature is 200-300℃, and the heating time is 0.5-2.0h.

[0018] The temperature of the reaction product is raised to 1400-1600°C by electromagnetic induction heating and maintained for 1-3 minutes; the temperature of the reaction product is raised to 800-1200°C by muffle furnace heating and maintained for 2-10 hours; the temperature of the reaction product is raised to 1600-2000°C by Joule ultrafast heating and maintained for 20-30 seconds.

[0019] Preferably, the solvent in step S3 includes one or more combinations of deionized water, dilute hydrochloric acid, ethanol, pyridine, acetone, tetrahydrofuran, and acetonitrile.

[0020] The second object of the present invention is to provide a rare earth silicon alloy material prepared by the above method.

[0021] The third object of the present invention is to provide an application of the above-mentioned rare earth silicon alloy material in a lithium battery, wherein the lithium battery comprises a negative electrode, an electrolyte and a positive electrode, and the negative electrode comprises the rare earth silicon alloy material and the rare earth silicon alloy material after pre-embedded lithium.

[0022] Preferably, the electrolyte is a combination of one or more liquid electrolytes and solid electrolytes, the liquid electrolyte is a combination of one or more carbonate electrolytes and ether electrolytes, and the solid electrolyte is a combination of one or more polymer electrolytes, oxide electrolytes, sulfide electrolytes, and halide electrolytes.

[0023] Preferably, the positive electrode is 10%-90% of positive electrode active material, 0-70% of electrolyte, 0-20% of carbon material and 0-10% of binder, the positive electrode active material is one or more combinations of lithium-containing positive electrode and lithium-free positive electrode, the carbon material is one or more combinations of acetylene black, Ketjen black, Super P, carbon nanotubes, graphite, graphene, soft carbon, hard carbon, activated carbon, and carbon fiber, and the binder is one or more combinations of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, and polyacrylate.

[0024] A fourth object of the present invention is to provide an application of the above-mentioned rare earth silicon alloy material in a lithium half-cell, wherein the lithium half-cell comprises a counter electrode, an electrolyte, and a working electrode, wherein the counter electrode is a combination of one or more of lithium metal, lithium-indium alloy, and lithium-graphite; the electrolyte is a combination of one or more of a liquid electrolyte and a solid electrolyte; and the working electrode is a rare earth silicon alloy material and a rare earth silicon alloy material pre-embedded with lithium.

[0025] Beneficial effects of the present invention:

[0026] The present invention prepares rare earth silicon alloy material by reduction method, and applies it as negative electrode in lithium battery, can suppress the volume change of silicon negative electrode to a certain extent, improve the conductivity of negative electrode, and enhance the cycle stability of battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The charge-discharge cycle performance of the lithium half-cell in Example 1 of the present invention, where the working electrode is a cerium-silicon alloy;

[0028] Figure 2The charge-discharge cycle performance of the lithium half-cell in Comparative Example 1 of the present invention, where the working electrode is a magnesium-silicon alloy;

[0029] Figure 3 SEM image of the cerium-silicon alloy material in Example 2 of the present invention;

[0030] Figure 4 SEM image of the cerium-silicon alloy material in Comparative Example 2 of the present invention;

[0031] Figure 5 Electrochemical impedance spectroscopy of the lithium half-cell in Example 3 of the present invention, where the working electrode is a yttrium-silicon alloy;

[0032] Figure 6 Electrochemical impedance spectroscopy of the lithium half-cell in Comparative Example 3 of the present invention, where the working electrode is a tin-silicon alloy;

[0033] Figure 7 The charge and discharge curves of the lithium battery in Example 4 of the present invention, where the negative electrode is a yttrium-silicon alloy;

[0034] Figure 8 The charge and discharge curve of the lithium battery in Comparative Example 4 of the present invention, wherein the negative electrode is yttrium-silicon alloy;

[0035] Figure 9 Charge and discharge curves of the lithium half-cell in Example 5 of the present invention, where the working electrode is a lanthanum-silicon alloy;

[0036] Figure 10 Charge and discharge curves of the lithium half-cell in Comparative Example 5 of the present invention, where the working electrode is an aluminum-silicon alloy;

[0037] Figure 11 SEM image of the lanthanum-silicon alloy material in Example 6 of the present invention;

[0038] Figure 12 SEM image of the lanthanum-silicon alloy material in Comparative Example 6 of the present invention;

[0039] Figure 13 Charge and discharge curves of the lithium half-cell in Example 7 of the present invention, where the working electrode is a gadolinium-silicon alloy;

[0040] Figure 14 Charge and discharge curves of the lithium half-cell in Example 7 of the present invention, where the working electrode is a titanium-silicon alloy;

[0041] Figure 15 XRD pattern of the gadolinium-silicon alloy in Example 8 of the present invention;

[0042] Figure 16 XRD pattern of the gadolinium-silicon alloy in Comparative Example 8 of the present invention;

[0043] Figure 17The charge and discharge curve of the lithium battery in Example 9 of the present invention, wherein the negative electrode is an ytterbium-silicon alloy;

[0044] Figure 18 The charge and discharge curve of the lithium battery in Comparative Example 9 of the present invention, wherein the negative electrode is an iron-silicon alloy.

[0045] Figure 19 Electrochemical impedance spectroscopy of the lithium battery in Example 10 of the present invention, wherein the negative electrode is an ytterbium-silicon alloy;

[0046] Figure 20 The electrochemical impedance spectroscopy of the lithium battery in Comparative Example 10 of the present invention shows that the negative electrode is an ytterbium-silicon alloy. DETAILED DESCRIPTION

[0047] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0048] Example 1

[0049] (1) The preparation method of cerium-silicon rare earth silicon alloy material is as follows:

[0050] The raw materials are cerium chloride, silicon powder, and metallic lithium. First, cerium chloride and silicon powder (the molar ratio of cerium to silicon is 0.05:0.95) are ball-milled to obtain a precursor at a speed of 300 r / min for 2 hours. Afterwards, the precursor and metallic lithium (the molar ratio of lithium to chlorine is 4:1) are placed in a mortar and ground manually for 10 minutes. The pellets are pressed with a 4t pressure and subjected to electromagnetic induction heating for 2 minutes to remove residual metallic lithium, thereby obtaining a cerium-silicon alloy containing lithium chloride impurities. Finally, the pellets are placed in a pyridine solution, stirred for 20 minutes, and filtered. This process is repeated three times to remove the lithium chloride impurities and obtain a cerium-silicon alloy material.

[0051] (2) A lithium half-cell with a cerium-silicon alloy as the working electrode and a lithium-indium alloy as the counter electrode was used to evaluate the battery performance of the cerium-silicon alloy. The specific preparation method is as follows:

[0052] The electrolyte is a halide solid electrolyte (Li3YBr6), and the working electrode is a cerium-silicon alloy material pre-embedded with lithium, prepared by hand grinding, with a molar ratio of lithium to silicon of 1:1. The counter electrode is a lithium-indium alloy.

[0053] 100mg of Li3YBr6 powder was weighed and placed in a circular mold. 2 tons of pressure was applied to form an electrolyte sheet. 5mg of pre-lithium-embedded cerium-silicon alloy was then added to both sides of the electrolyte sheet. A 9mm-diameter lithium-indium alloy was added to the other side. 4 tons of pressure was applied to form a lithium half-cell. The inner diameter of the circular mold was 10mm.

[0054] (3) The lithium battery with cerium-silicon alloy material as the negative electrode is prepared as follows:

[0055] The electrolyte is a rare earth halide solid electrolyte (Li3YBr6), the negative electrode is a cerium-silicon alloy material with pre-embedded lithium, and the positive electrode is a mixture of lithium titanate, Li3YBr6, and Ketjen black with a mass ratio of 3:6:1.

[0056] 100mg of Li3YBr6 powder was weighed and placed in a circular mold. 2 tons of pressure was applied to form an electrolyte sheet. 10mg of positive electrode was then added to one side of the electrolyte sheet, and a pre-lithium-embedded cerium-silicon alloy was added to the other side. 4 tons of pressure was applied to form a lithium battery. The inner diameter of the circular mold was 10mm.

[0057] Comparative Example 1

[0058] (1) The preparation method of the magnesium-silicon alloy material is different from that of Example 1 in that the raw materials are magnesium chloride, silicon powder, and metallic lithium.

[0059] (2) A lithium half-cell with a magnesium-silicon alloy material as the working electrode and a lithium-indium alloy as the counter electrode was used to evaluate the battery performance of the magnesium-silicon alloy material. The preparation method differed from that in Example 1 in that the cerium-silicon alloy was replaced by the magnesium-silicon alloy.

[0060] (3) A lithium battery using a magnesium-silicon alloy material as a negative electrode, the preparation method is different from that of Example 1 in that the cerium-silicon alloy is replaced by a magnesium-silicon alloy.

[0061] Figure 1 is the charge-discharge cycle performance of the lithium half-cell in Example 1 (working electrode: cerium-silicon alloy), Figure 2 The charge and discharge cycle performance of the lithium half-cell in Comparative Example 1 (working electrode: magnesium-silicon alloy). Figure 1 The capacity of the medium charge and discharge curve is high and the attenuation is not obvious; Figure 2 The capacity of the middle charge-discharge curve is low, and the capacity decay is obvious, which shows that the cerium-silicon alloy of Example 1 can stabilize the electrode structure and promote charge diffusion.

[0062] Example 2

[0063] (1) The preparation method of cerium-silicon rare earth silicon alloy material is as follows:

[0064] The raw materials are cerium chloride, silicon powder, and metallic lithium. First, cerium chloride and silicon powder (the molar ratio of cerium to silicon is 0.10:0.90) are ball-milled to obtain a precursor at a ball mill speed of 300 r / min for 2 hours. Afterwards, the precursor and metallic lithium (the molar ratio of lithium to chlorine is 4:1) are placed in a mortar and manually ground for 10 minutes. The pellets are pressed with 4 tons and subjected to electromagnetic induction heating for 2 minutes to remove residual metallic lithium, thereby obtaining a cerium-silicon alloy containing lithium chloride impurities. Finally, the pellets are placed in a pyridine solution, stirred for 10 minutes, and filtered. This process is repeated three times to remove the lithium chloride impurities and obtain a cerium-silicon alloy material.

[0065] (2) A lithium half-cell with a cerium-silicon alloy as the working electrode and a lithium-indium alloy as the counter electrode was used to evaluate the battery performance of the cerium-silicon alloy. The specific preparation method is as follows:

[0066] The electrolyte is a halide solid electrolyte (Li3YCl6), and the working electrode is a cerium-silicon alloy material pre-embedded with lithium, prepared by hand grinding, with a molar ratio of lithium to silicon of 2:1. The counter electrode is a lithium-indium alloy.

[0067] 100mg of Li3YCl6 powder was weighed and placed in a circular mold. 2t of pressure was applied to form an electrolyte sheet. 5mg of pre-lithium-embedded cerium-silicon alloy was then added to both sides of the electrolyte sheet. A 9mm-diameter lithium-indium alloy was added to the other side. 4t of pressure was applied to form a lithium half-cell. The inner diameter of the circular mold was 10mm.

[0068] (3) The specific preparation method of the lithium battery using cerium-silicon alloy material as the negative electrode is as follows:

[0069] The electrolyte is a rare earth halide solid electrolyte (Li3YCl6), the negative electrode is a cerium-silicon alloy material with pre-embedded lithium, and the positive electrode is a mixture of lithium titanate, Li3YCl6, and Ketjen black with a mass ratio of 3:6:1.

[0070] 100mg of Li₃YCl₆ powder was weighed and placed in a circular mold. 2t of pressure was applied to form an electrolyte sheet. 10mg of positive electrode was then added to one side of the electrolyte sheet, and a pre-lithium-embedded cerium-silicon alloy was added to the other side. 4t of pressure was applied to form a lithium battery. The inner diameter of the circular mold was 10mm.

[0071] Comparative Example 2

[0072] (1) The preparation method of cerium-silicon rare earth silicon alloy material is as follows:

[0073] The raw materials are cerium powder and silicon powder. First, the cerium powder and silicon powder (at a molar ratio of 0.05:0.95) are ball-milled at 300 rpm for 2 hours to produce a precursor. The precursor is then pressed into pellets using a 4-ton press and subjected to electromagnetic induction heating for 2 minutes to produce a cerium-silicon alloy.

[0074] (2) A lithium half-cell with a cerium-silicon alloy material as the working electrode and a lithium-indium alloy as the counter electrode is used to evaluate the battery performance of the cerium-silicon alloy material. The specific preparation method is the same as that in Example 2.

[0075] (3) The specific preparation method of the lithium battery using cerium-silicon alloy material as the negative electrode is the same as that of Example 2.

[0076] Figure 3 is the SEM image of the cerium-silicon alloy material in Example 2, Figure 4 This is the SEM image of the cerium-silicon alloy material in Comparative Example 2. Figure 3 The material has uniform morphology and is composed of nano-scale particles. Figure 4 The material morphology is uneven, with nano-scale particles coexisting with large particles larger than 10 microns. This indicates that the method for preparing the cerium-silicon alloy material in Example 2 is better and can obtain a uniform cerium-silicon alloy material.

[0077] Example 3

[0078] (1) The preparation method of yttrium-silicon rare earth silicon alloy material is as follows:

[0079] The raw materials are yttrium oxide, silicon powder, and carbon powder. First, yttrium chloride and silicon powder (yttrium to silicon molar ratio of 0.20:0.80) are ball-milled at 300 rpm for 2 hours to produce a precursor. The precursor is then manually ground with carbon powder (carbon to oxygen molar ratio of 1:1) in a mortar for 10 minutes. The sample is then subjected to ultrafast Joule heating (1800°C for 30 seconds) to reduce the yttrium oxide and produce a yttrium-silicon alloy.

[0080] (2) A lithium half-cell with yttrium-silicon alloy as the working electrode and lithium metal as the counter electrode is used to evaluate the battery performance of yttrium-silicon alloy. The specific preparation method is as follows:

[0081] The electrolyte is a commercial carbonate electrolyte, the working electrode is a yttrium-silicon alloy material pre-embedded with lithium, the preparation method is ball milling, the molar ratio of lithium to silicon is 1:2, the ball milling speed is 300r / min, the ball milling time is 1h, and the counter electrode is lithium metal.

[0082] Cut the glass fiber diaphragm into discs with a diameter of 16 mm and then soak them in a carbonate electrolyte with a volume of 200-400 μL to obtain an electrolyte / diaphragm sheet. Preparation of the working electrode: Mix yttrium-silicon alloy with acetylene black and PVDF in a mass ratio of 8:1:1. Apply the working electrode material to copper foil by smearing. The smearing solvent is N-methylpyrrolidone, and the working electrode loading is 5.0-10.0 mg / cm 2 The copper foil loaded with the working electrode was cut into discs to obtain a working electrode sheet with a diameter of 10 mm. The lithium metal was cold-pressed into thin sheets and cut into discs with a diameter of 12 mm and a thickness of 100 μm to obtain a counter electrode sheet.

[0083] Place the cut discs into the CR2032 button battery mold in the order of counter electrode sheet, electrolyte / diaphragm, and working electrode sheet, and package them at a packaging pressure of 0.5t.

[0084] (3) A lithium battery using yttrium-silicon alloy as a negative electrode, the specific preparation method is as follows:

[0085] The electrolyte is a commercial carbonate electrolyte, the negative electrode is a yttrium-silicon alloy material, and the positive electrode is a mixture of lithium cobalt oxide, acetylene black, and PVDF.

[0086] The glass fiber separator was cut into discs with a diameter of 16 mm, and then soaked in an ether electrolyte with a volume of 200-400 μL to obtain an electrolyte / separator sheet.

[0087] Preparation of the positive electrode: Lithium cobalt oxide, acetylene black, and PVDF were mixed in a mass ratio of 8:1:1. The working electrode material was loaded onto aluminum foil by smearing. The smearing solvent was N-methylpyrrolidone, and the working electrode loading was 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode was cut into discs to obtain positive electrode sheets with a diameter of 10 mm.

[0088] Preparation of the negative electrode: Yttrium-silicon alloy, acetylene black, and PVDF were mixed in a mass ratio of 8:1:1 and loaded onto copper foil by smearing. The solvent for the smearing was N-methylpyrrolidone, and the negative electrode loading was 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode was cut into discs to obtain a negative electrode sheet with a diameter of 10 mm.

[0089] Place the cut discs into the CR2032 button battery mold in the order of negative electrode sheet, electrolyte / diaphragm, and positive electrode sheet, and package them with a packaging pressure of 0.5t.

[0090] Comparative Example 3

[0091] (1) The preparation method of the tin-silicon alloy material is different from that of Example 3 in that the raw materials are tin oxide, silicon powder, and carbon powder, and the molar ratio of yttrium to silicon is 0.10:0.90.

[0092] (2) A lithium half-cell with a tin-silicon alloy material as the working electrode and lithium metal as the counter electrode was used to evaluate the battery performance of the tin-silicon alloy material. The preparation method was different from that in Example 3 in that the yttrium-silicon alloy was replaced by a tin-silicon alloy, the molar ratio of lithium to silicon was 1:1, and the ball milling time was 2 h.

[0093] (3) The specific preparation method of the lithium battery using tin-silicon alloy material as the negative electrode is different from that of Example 3 in that the yttrium-silicon alloy is replaced by tin-silicon alloy.

[0094] Figure 5 is the electrochemical impedance spectroscopy of the lithium half-cell in Example 3 (working electrode: yttrium-silicon alloy), Figure 6 This is the electrochemical impedance spectroscopy of the lithium half-cell in Comparative Example 3 (working electrode: tin-silicon alloy). Figure 5 The impedance of the electrochemical impedance spectroscopy is low and the interface impedance is not obvious; Figure 6 The electrochemical impedance spectrum has a large interface impedance, indicating that the yttrium-silicon alloy of Example 3 can stabilize the electrode structure and promote charge diffusion.

[0095] Example 4

[0096] (1) The preparation method of yttrium-silicon rare earth silicon alloy material is as follows:

[0097] The raw materials are yttrium oxide, silicon powder, and carbon powder. First, yttrium chloride and silicon powder (yttrium to silicon molar ratio of 0.10:0.90) are ball-milled at 300 rpm for 2 hours to produce a precursor. The precursor is then manually ground with carbon powder (carbon to oxygen molar ratio of 1:1) in a mortar for 10 minutes. The sample is then subjected to ultrafast Joule heating (1800°C for 20 seconds) to reduce the yttrium oxide and produce a yttrium-silicon alloy.

[0098] (2) A lithium half-cell with yttrium-silicon alloy as the working electrode and lithium metal as the counter electrode is used to evaluate the battery performance of yttrium-silicon alloy. The specific preparation method is as follows:

[0099] The electrolyte is a commercial ether electrolyte, the working electrode is a yttrium-silicon alloy material pre-embedded with lithium, the preparation method is ball milling, the molar ratio of lithium to silicon is 1:1, the ball milling speed is 300r / min, the ball milling time is 2h, and the counter electrode is lithium metal.

[0100] Cut the glass fiber diaphragm into discs with a diameter of 16 mm and then soak them in an ether electrolyte solution with a volume of 200-400 μL to obtain an electrolyte / diaphragm sheet. Preparation of the working electrode: Mix yttrium-silicon alloy, carbon nanotubes, and PVDF in a mass ratio of 8:1:1. Apply the working electrode material to copper foil by smearing. The smearing solvent is N-methylpyrrolidone, and the working electrode loading is 5.0-10.0 mg / cm 2 The copper foil loaded with the working electrode was cut into discs to obtain a working electrode sheet with a diameter of 10 mm. The lithium metal was cold-pressed into thin sheets and cut into discs with a diameter of 12 mm and a thickness of 100 μm to obtain a counter electrode sheet.

[0101] Place the cut discs into the CR2032 button battery mold in the order of counter electrode sheet, electrolyte / diaphragm, and working electrode sheet, and package them at a packaging pressure of 0.5t.

[0102] (3) A lithium battery using yttrium-silicon alloy as a negative electrode, the specific preparation method is as follows:

[0103] The electrolyte is a commercial ether electrolyte, the negative electrode is yttrium-silicon alloy material, and the positive electrode is lithium cobalt oxide.

[0104] The glass fiber separator was cut into discs with a diameter of 16 mm, and then soaked in an ether electrolyte with a volume of 200-400 μL to obtain an electrolyte / separator sheet.

[0105] Preparation of the positive electrode: LiCoO3, CNTs, and PVDF were mixed in a mass ratio of 8:1:1. The working electrode material was loaded onto aluminum foil by smearing. The smearing solvent was N-methylpyrrolidone, and the working electrode loading was 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode was cut into discs to obtain positive electrode sheets with a diameter of 10 mm.

[0106] Preparation of the negative electrode: Yttrium-silicon alloy, carbon nanotubes, and PVDF were mixed in a mass ratio of 8:1:1 and loaded onto copper foil by coating. The coating solvent was N-methylpyrrolidone, and the negative electrode loading was 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode was cut into discs to obtain a negative electrode sheet with a diameter of 10 mm.

[0107] Place the cut discs into the CR2032 button battery mold in the order of negative electrode sheet, electrolyte / diaphragm, and positive electrode sheet, and package them with a packaging pressure of 0.5t.

[0108] Comparative Example 4

[0109] (1) The preparation method of yttrium-silicon rare earth silicon alloy material is as follows:

[0110] The raw materials are yttrium powder and silicon powder. First, the yttrium powder and silicon powder (at a molar ratio of yttrium to silicon of 0.10:0.90) are ball-milled at a speed of 300 rpm for 2 hours to produce a precursor. The precursor is then subjected to ultrafast Joule heating (1800°C for 20 seconds) to produce a yttrium-silicon alloy.

[0111] (2) A lithium half-cell with yttrium-silicon alloy material as the working electrode and lithium metal as the counter electrode is used to evaluate the battery performance of yttrium-silicon alloy material. Its specific preparation method is the same as that of Example 4.

[0112] (3) The specific preparation method of the lithium battery using yttrium-silicon alloy material as the negative electrode is the same as that of Example 4.

[0113] Figure 7 is the charge and discharge curve of the lithium battery in Example 4 (negative electrode: yttrium-silicon alloy), Figure 8 This is the charge and discharge curve of the lithium battery in Comparative Example 4 (negative electrode: yttrium-silicon alloy). Figure 7 The capacity of the intermediate charge and discharge curves is higher and almost overlaps; Figure 8 The capacity of the charge-discharge curve is low, and the capacity decay is obvious; this shows that the method for preparing the yttrium-silicon alloy in Example 4 is better, and the obtained yttrium-silicon alloy can more fully stabilize the electrode structure and promote charge diffusion.

[0114] Example 5

[0115] (1) The preparation method of lanthanum-silicon rare earth silicon alloy material is as follows:

[0116] The raw materials are lanthanum chloride, silicon powder, and sodium metal. First, lanthanum chloride and silicon powder (the molar ratio of lanthanum to silicon is 0.02:0.98) are ball-milled to obtain a precursor at a speed of 300 rpm for 2 hours. The precursor and excess sodium metal (the molar ratio of sodium to chloride is 2:1) are placed in a mortar and ground manually for 10 minutes. The pellets are then pressed into a 4t pellet and heated in a muffle furnace at 800°C for 2 hours to remove residual sodium metal, resulting in a lanthanum-silicon alloy containing sodium chloride impurities. Finally, the reaction product is placed in anhydrous ethanol, stirred for 30 minutes, filtered, and vacuum-dried at 80°C for 10 hours to remove the sodium chloride impurity, resulting in a lanthanum-silicon alloy material.

[0117] (2) A lithium half-cell with a lanthanum-silicon alloy material as the working electrode and lithium metal as the counter electrode is used to evaluate the battery performance of the lanthanum-silicon alloy material. The specific preparation method is as follows:

[0118] The electrolyte is a sulfide solid electrolyte (Li7P3S 11), the working electrode is a lanthanum-silicon alloy material pre-embedded with lithium, prepared by hand grinding, with a molar ratio of lithium to silicon of 1:1. The counter electrode is lithium metal.

[0119] Weigh 80 mg of Li7P3S 11 The powder is placed in a circular mold and subjected to a pressure of 2 tons to form an electrolyte sheet. Next, 5 mg of a lanthanum-silicon alloy pre-embedded with lithium is added to one side of the electrolyte sheet and a pressure of 4 tons is applied. A 9 mm diameter lithium sheet is then added to the other side and a pressure of 0.5 tons is applied to form a lithium half-cell. The inner diameter of the circular mold is 10 mm.

[0120] (3) The specific preparation method of the lithium battery using lanthanum-silicon alloy material as the negative electrode is as follows:

[0121] The electrolyte is a sulfide solid electrolyte (Li7P3S 11 ), the negative electrode is a lanthanum-silicon alloy material with pre-embedded lithium, and the positive electrode is NCM811, Li7P3S 11 , a mixture of acetylene black, with a mass ratio of 7:2.8:0.2.

[0122] Weigh 80 mg of Li7P3S 11 The powder is placed in a circular mold and subjected to a pressure of 2 tons to form an electrolyte sheet. 10 mg of cathode material is then added to one side of the electrolyte sheet, and 5 mg of a lanthanum-silicon alloy pre-intercalated with lithium is added to the other side. A pressure of 4 tons is then applied to form a lithium battery. The inner diameter of the circular mold is 10 mm.

[0123] Comparative Example 5

[0124] (1) The preparation method of the aluminum-silicon alloy material is different from that of Example 5 in that the raw materials are aluminum chloride, silicon powder, and metallic sodium.

[0125] (2) A lithium half-cell with an aluminum-silicon alloy material as the working electrode and lithium metal as the counter electrode was used to evaluate the battery performance of the lanthanum-silicon alloy material. The specific preparation method was different from that of Example 5 in that the lanthanum-silicon alloy was replaced with an aluminum-silicon alloy.

[0126] (3) The specific preparation method of the lithium battery using aluminum-silicon alloy material as the negative electrode is different from that of Example 5 in that the lanthanum-silicon alloy is replaced by aluminum-silicon alloy.

[0127] Figure 9 is the charge-discharge curve of the lithium half-cell in Example 5 (working electrode: lanthanum-silicon alloy), Figure 10 is the charge and discharge curve of the lithium half-cell in comparative example 5 (working electrode: aluminum-silicon alloy). Figure 10 compared to, Figure 9The capacity of the medium charge-discharge curve is higher, indicating that the lanthanum-silicon alloy of Example 5 can stabilize the electrode structure and fully exert the electrode capacity.

[0128] Example 6

[0129] (1) The preparation method of lanthanum-silicon rare earth silicon alloy material is as follows:

[0130] The raw materials are lanthanum chloride, silicon powder, and metallic sodium. First, lanthanum chloride and silicon powder (the molar ratio of lanthanum to silicon is 0.01:0.99) are ball-milled to obtain a precursor at a speed of 300 rpm for 2 hours. The precursor is then manually ground with excess metallic sodium (the molar ratio of sodium to chloride is 2:1) in a mortar for 10 minutes. The pellets are then pressed into a 4-ton pelletizer and heated in a muffle furnace at 800°C for 2 hours to remove residual metallic sodium, resulting in a lanthanum-silicon alloy containing sodium chloride as an impurity. Finally, the reaction product is placed in anhydrous ethanol, stirred for 20 minutes, filtered, and vacuum-dried at 80°C for 5 hours to remove the sodium chloride impurity, resulting in a lanthanum-silicon alloy material.

[0131] (2) A lithium half-cell with a lanthanum-silicon alloy material as the working electrode and lithium metal as the counter electrode is used to evaluate the battery performance of the lanthanum-silicon alloy material. The specific preparation method is as follows:

[0132] The electrolyte is a sulfide solid electrolyte (Li3PS4), and the working electrode is a lanthanum-silicon alloy material pre-embedded with lithium, prepared by hand grinding, with a molar ratio of lithium to silicon of 1:2. The counter electrode is lithium metal.

[0133] 80mg of Li3PS4 powder was weighed and placed in a circular mold. 2t of pressure was applied to form an electrolyte sheet. 5mg of a lanthanum-silicon alloy pre-embedded with lithium was then added to one side of the electrolyte sheet. 4t of pressure was then applied. A 9mm-diameter lithium sheet was then added to the other side. 0.5t of pressure was then applied to form a lithium half-cell. The inner diameter of the circular mold was 10mm.

[0134] (3) The specific preparation method of the lithium battery using lanthanum-silicon alloy material as the negative electrode is as follows:

[0135] The electrolyte is a sulfide solid electrolyte (Li3PS4), the negative electrode is a lanthanum-silicon alloy material with pre-embedded lithium, and the positive electrode is a mixture of NCM622, Li3PS4, and acetylene black with a mass ratio of 7:2.8:0.2.

[0136] 80mg of Li3PS4 powder was weighed and placed in a circular mold. 2t of pressure was applied to form an electrolyte sheet. 10mg of cathode material was then added to one side of the electrolyte sheet, and 5mg of a pre-lithium-embedded lanthanum-silicon alloy was added to the other side. 4t of pressure was applied to form a lithium battery. The inner diameter of the circular mold was 10mm.

[0137] Comparative Example 6

[0138] (1) The preparation method of lanthanum-silicon rare earth silicon alloy material is as follows:

[0139] The raw materials are lanthanum powder, silicon powder, and sodium metal. The lanthanum powder and silicon powder (the molar ratio of lanthanum to silicon is 0.01:0.99) are ball-milled at a speed of 300 rpm for 2 hours to produce a precursor. The precursor is then pressed into a 4-ton pellet and heated in a muffle furnace at 1100°C for 10 hours to produce a lanthanum-silicon alloy.

[0140] (2) A lithium half-cell with a lanthanum-silicon alloy material as the working electrode and lithium metal as the counter electrode was used to evaluate the battery performance of the lanthanum-silicon alloy material. The specific preparation method was the same as that in Example 6.

[0141] (3) The specific preparation method of the lithium battery using lanthanum-silicon alloy material as the negative electrode is the same as that of Example 6.

[0142] Figure 11 is the SEM image of the lanthanum-silicon alloy material in Example 6, Figure 12 This is the SEM image of the lanthanum-silicon alloy material in Comparative Example 6. Figure 11 The material particles have uniform morphology; Figure 12 The morphology of the material particles is uneven, indicating that the method for preparing the lanthanum-silicon alloy material in Example 6 is better and can obtain a uniform lanthanum-silicon alloy material.

[0143] Example 7

[0144] (1) The preparation method of gadolinium-silicon rare earth silicon alloy material is as follows:

[0145] The raw materials are gadolinium oxide, silicon powder, and metallic lithium. First, gadolinium oxide and silicon powder (molar ratio of gadolinium to silicon is 0.05:0.95) are manually ground and mixed to obtain a precursor for 20 minutes. The precursor and metallic lithium (molar ratio of lithium to oxygen is 3:1) are then placed in a mortar and manually ground for 10 minutes. The mixture is then treated with electromagnetic induction heating for 1 minute to remove residual metallic lithium, resulting in a gadolinium-silicon alloy containing lithium oxide impurities. Finally, the mixture is stirred in a 0.5M dilute hydrochloric acid solution for 30 minutes, filtered, washed, and dried under vacuum at 80°C for 10 hours to obtain the gadolinium-silicon alloy material.

[0146] (2) A lithium half-cell with a gadolinium-silicon alloy material as the working electrode and lithium metal as the counter electrode was used to evaluate the battery performance of the gadolinium-silicon alloy material. The specific preparation method is as follows:

[0147] The electrolyte is a commercial oxide solid electrolyte sheet (Li7La3Zr2O 12 , LLZO), thickness 500 μm; the counter electrode is lithium metal.

[0148] Preparation of the working electrode: Mix gadolinium-silicon alloy, Ketjen black, and PVDF in a mass ratio of 8:1:1. Apply the working electrode material to copper foil by smearing. The smearing solvent is N-methylpyrrolidone, and the working electrode loading is 5.0-10.0 mg / cm 2 The copper foil loaded with the working electrode was cut into discs to obtain a working electrode sheet with a diameter of 10 mm. The lithium metal was cold-pressed into thin sheets and cut into discs with a diameter of 12 mm and a thickness of 100 μm to obtain a counter electrode sheet.

[0149] Place the cut discs into the CR2032 button battery mold in the order of counter electrode sheet, electrolyte / diaphragm, and working electrode sheet. Add 0.1 mL of ether electrolyte between the electrode sheet and the electrolyte sheet, and seal with a sealing pressure of 0.5t.

[0150] (3) A lithium battery using a gadolinium-silicon alloy material as a negative electrode, the specific preparation method is as follows:

[0151] The electrolyte is a commercial LLZO sheet with a thickness of 500μm; the negative electrode is a gadolinium-silicon alloy material; and the positive electrode is a mixture of lithium iron phosphate, Ketjen black, and PVDF.

[0152] Preparation of the positive electrode: Lithium iron phosphate, Ketjen black, and PVDF were mixed in a mass ratio of 7:2:1. The working electrode material was loaded onto aluminum foil by smearing. The smearing solvent was N-methylpyrrolidone, and the working electrode loading was 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode was cut into discs to obtain positive electrode sheets with a diameter of 10 mm.

[0153] Preparation of the negative electrode: Mix gadolinium-silicon alloy, Ketjen black, and PVDF in a mass ratio of 8:1:1. The negative electrode material is then applied to copper foil by smearing. The solvent for the smearing is N-methylpyrrolidone, and the negative electrode loading is 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode was cut into discs to obtain a negative electrode sheet with a diameter of 10 mm.

[0154] Place the cut discs into the CR2032 button battery mold in the order of negative electrode sheet, electrolyte / diaphragm, and positive electrode sheet. Add 0.1 mL of ether electrolyte between the electrode sheet and the electrolyte sheet, and seal with a sealing pressure of 0.5t.

[0155] Comparative Example 7

[0156] (1) The preparation method of the titanium-silicon alloy material is different from that of Example 7 in that the raw materials are titanium oxide, silicon powder, and metallic lithium.

[0157] (2) A lithium half-cell with titanium-silicon alloy as the working electrode and lithium metal as the counter electrode was used to evaluate the battery performance of the titanium-silicon alloy. The specific preparation method was different from that of Example 7 in that the gadolinium-silicon alloy was replaced with the titanium-silicon alloy.

[0158] (3) The specific preparation method of the lithium battery using titanium-silicon alloy as the negative electrode is different from that of Example 7 in that the gadolinium-silicon alloy is replaced by titanium-silicon alloy.

[0159] Figure 13 is the charge and discharge curve of the lithium half-cell in Example 7 (working electrode: gadolinium-silicon alloy), Figure 14 2 is the charge and discharge curve of the lithium half-cell in Comparative Example 7 (working electrode: titanium-silicon alloy). Figure 13 The capacity of the medium charge and discharge curve is higher, and the capacity decay is relatively less obvious; Figure 14 The capacity of the intermediate charge-discharge curve is low, and the capacity decay is obvious, indicating that the gadolinium-silicon alloy of Example 7 can stabilize the electrode structure and promote charge diffusion.

[0160] Example 8

[0161] (1) The preparation method of gadolinium-silicon rare earth silicon alloy material is as follows:

[0162] The raw materials are gadolinium oxide, silicon powder, and metallic lithium. First, gadolinium oxide and silicon powder (molar ratio of gadolinium to silicon is 0.15:0.85) are manually ground and mixed to obtain a precursor for 30 minutes. The precursor and metallic lithium (molar ratio of lithium to oxygen is 3:1) are then placed in a mortar and manually ground for 10 minutes. The mixture is then treated with electromagnetic induction heating for 2 minutes to remove residual metallic lithium, resulting in a gadolinium-silicon alloy containing lithium oxide impurities. Finally, the mixture is stirred in a 0.5M dilute hydrochloric acid solution for 30 minutes, filtered, washed, and dried under vacuum at 90°C for 5 hours to obtain the gadolinium-silicon alloy material.

[0163] (2) A lithium half-cell is used to evaluate the battery performance of gadolinium-silicon alloy materials, wherein the working electrode is gadolinium-silicon alloy and the electrolyte is a commercial oxide solid electrolyte sheet (Li 1.3 Al 0.3 Ti 1.7 (PO4)3, LATP), thickness 500μm; the counter electrode is lithium metal. The specific preparation method is as follows:

[0164] Preparation of the working electrode: Mix gadolinium-silicon alloy, Super P, and PVDF in a mass ratio of 8:1:1. Apply the working electrode material to copper foil by smearing. The smearing solvent is N-methylpyrrolidone, and the working electrode loading is 5.0-10.0 mg / cm 2The copper foil loaded with the working electrode was cut into discs to obtain a working electrode sheet with a diameter of 10 mm. The lithium metal was cold-pressed into thin sheets and cut into discs with a diameter of 12 mm and a thickness of 100 μm to obtain a counter electrode sheet.

[0165] Place the cut discs into the CR2032 button battery mold in the order of counter electrode sheet, electrolyte / diaphragm, and working electrode sheet. Add 0.1 mL of carbonate electrolyte between the electrode sheet and the electrolyte sheet, and package at a packaging pressure of 0.5t.

[0166] (3) A lithium battery using a gadolinium-silicon alloy material as a negative electrode, the specific preparation method is as follows:

[0167] The electrolyte is a commercial LATP sheet with a thickness of 500μm; the negative electrode is a gadolinium-silicon alloy material; and the positive electrode is a mixture of lithium iron phosphate, Super P, and PVDF.

[0168] Preparation of the positive electrode: Lithium iron phosphate, Super P, and PVDF were mixed in a mass ratio of 8:1:1. The working electrode material was loaded onto aluminum foil by smearing. The smearing solvent was N-methylpyrrolidone, and the working electrode loading was 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode was cut into discs to obtain positive electrode sheets with a diameter of 10 mm.

[0169] Preparation of the negative electrode: Mix gadolinium-silicon alloy, Super P, and PVDF in a mass ratio of 8:1:1, and apply the negative electrode material to copper foil by smearing. The solvent for the smearing is N-methylpyrrolidone, and the negative electrode loading is 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode was cut into discs to obtain a negative electrode sheet with a diameter of 10 mm.

[0170] Place the cut discs into the CR2032 button battery mold in the order of negative electrode sheet, electrolyte / separator, and positive electrode sheet. Add 0.1 mL of carbonate electrolyte between the electrode sheet and the electrolyte sheet, and package them at a packaging pressure of 0.5t.

[0171] Comparative Example 8

[0172] (1) The preparation method of gadolinium-silicon rare earth silicon alloy material is as follows:

[0173] The raw materials are gadolinium powder and silicon powder. The gadolinium powder and silicon powder (molar ratio of gadolinium to silicon: 0.15:0.85) are manually ground together for 30 minutes to produce a precursor. The precursor is then treated with electromagnetic induction heating for 2 minutes to produce a gadolinium-silicon alloy.

[0174] (2) A lithium half-cell is used to evaluate the battery performance of gadolinium-silicon alloy materials. The specific preparation method is the same as that of Example 8.

[0175] (3) The specific preparation method of the lithium battery using gadolinium-silicon alloy material as the negative electrode is the same as that of Example 8.

[0176] Figure 15 is the XRD pattern of the gadolinium-silicon alloy material in Example 8, Figure 16 is the XRD pattern of the gadolinium-silicon alloy material in Comparative Example 8. Figure 16 compared to, Figure 15 The impurity peaks are not obvious, and the material phase is relatively pure; this shows that the method for preparing the gadolinium-silicon alloy material in Example 8 is better and can obtain a high-purity gadolinium-silicon alloy material.

[0177] Example 9

[0178] (1) The preparation method of ytterbium-silicon rare earth silicon alloy material is as follows:

[0179] The raw materials are ytterbium chloride, silicon powder, and sodium metal. First, ytterbium chloride and silicon powder (a molar ratio of ytterbium to silicon of 0.1:0.9) are mixed via a liquid phase method to obtain a precursor. The solvent is ethanol, stirred for 1 hour, and then vacuum-dried at 80°C for 5 hours. The precursor and sodium metal (a molar ratio of sodium to chlorine of 2:1) are then manually ground in a mortar for 10 minutes. The mixture is then heated in a muffle furnace at 900°C for 2 hours to remove any residual sodium metal, resulting in an ytterbium-silicon alloy containing sodium chloride as an impurity. Finally, the mixture is stirred in anhydrous ethanol for 30 minutes, filtered, washed, and vacuum-dried at 80°C for 10 hours to obtain the ytterbium-silicon alloy material.

[0180] (2) A lithium half-cell used to evaluate the battery performance of ytterbium-silicon alloy materials, wherein the working electrode is ytterbium-silicon alloy; the electrolyte is a commercial polymer solid electrolyte membrane with a thickness of 100 μm; and the counter electrode is lithium-indium alloy. The specific preparation method is as follows:

[0181] Preparation of the working electrode: Ytterbium-silicon alloy, carbon nanotubes, and PVDF were mixed in a mass ratio of 8:1:1. The working electrode material was loaded onto copper foil by smearing. The smearing solvent was N-methylpyrrolidone, and the working electrode loading was 5.0-10.0 mg / cm 2 The copper foil loaded with the working electrode was cut into discs to obtain a working electrode sheet with a diameter of 10 mm. The lithium-indium alloy was cold-pressed into thin sheets and cut into discs with a diameter of 12 mm and a thickness of 100 μm to obtain a counter electrode sheet.

[0182] The cut discs were placed into the CR2032 button battery mold in the order of the counter electrode sheet, polymer solid electrolyte membrane, and working electrode sheet, and packaged at a packaging pressure of 0.5t.

[0183] (3) A lithium battery using ytterbium-silicon alloy material as a negative electrode, the specific preparation method is as follows:

[0184] The electrolyte is a commercial polymer solid electrolyte membrane with a thickness of 100μm; the negative electrode is a ytterbium-silicon alloy material; and the positive electrode is a mixture of lithium titanate, carbon nanotubes, and PVDF.

[0185] Preparation of the positive electrode: Lithium titanate, carbon nanotubes, and PVDF were mixed in a mass ratio of 8:1:1. The working electrode material was loaded onto aluminum foil by smearing. The smearing solvent was N-methylpyrrolidone, and the working electrode loading was 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode was cut into discs to obtain positive electrode sheets with a diameter of 10 mm.

[0186] Preparation of the negative electrode: Ytterbium-silicon alloy, carbon nanotubes, and PVDF were mixed in a mass ratio of 8:1:1 and loaded onto copper foil by coating. The coating solvent was N-methylpyrrolidone, and the negative electrode loading was 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode was cut into discs to obtain a negative electrode sheet with a diameter of 10 mm.

[0187] Place the cut discs into the CR2032 button battery mold in the order of negative electrode sheet, polymer solid electrolyte membrane, and positive electrode sheet, and package them with a packaging pressure of 0.5t.

[0188] Comparative Example 9

[0189] (1) The preparation method of the iron-silicon alloy material is different from that of Example 9 in that the raw materials are ferric chloride, silicon powder, and metallic sodium, and the ytterbium-silicon alloy is replaced by the iron-silicon alloy.

[0190] (2) A lithium half-cell is used to evaluate the battery performance of an iron-silicon alloy material. The specific preparation method is different from that of Example 9 in that the ytterbium-silicon alloy is replaced by the iron-silicon alloy.

[0191] (3) The specific preparation method of the lithium battery using an iron-silicon alloy material as the negative electrode is different from that of Example 9 in that the ytterbium-silicon alloy is replaced by the iron-silicon alloy.

[0192] Figure 17 is the charge and discharge curve of the lithium battery in Example 9 (negative electrode: ytterbium-silicon alloy), Figure 18 This is the charge and discharge curve of the lithium battery in Comparative Example 9 (negative electrode: iron-silicon alloy). Figure 17 The capacity of the intermediate charge and discharge curves is higher and almost overlaps; Figure 18The capacity of the middle charge-discharge curve is low, and the capacity decay is obvious, which shows that the ytterbium-silicon alloy of Example 9 can stabilize the electrode structure and promote charge diffusion.

[0193] Example 10

[0194] (1) The preparation method of ytterbium-silicon rare earth silicon alloy material is as follows:

[0195] The raw materials are ytterbium chloride, silicon powder, and metallic lithium. First, a precursor is prepared by mixing ytterbium chloride and silicon powder (with a molar ratio of ytterbium to silicon of 0.25:0.75) via a liquid phase method. The solvent is ethanol, stirred for 1 hour, and then dried under vacuum at 70°C for 10 hours. The precursor and metallic lithium (with a molar ratio of lithium to chlorine of 2:1) are then manually ground in a mortar for 10 minutes. The mixture is then heated in a muffle furnace at 900°C for 2 hours to remove any residual metallic lithium, resulting in an ytterbium-silicon alloy containing lithium chloride as an impurity. Finally, the mixture is stirred in anhydrous ethanol for 30 minutes, filtered, washed, and dried under vacuum at 70°C for 10 hours to obtain the ytterbium-silicon alloy material.

[0196] (2) A lithium half-cell used to evaluate the battery performance of ytterbium-silicon alloy materials, wherein the working electrode is ytterbium-silicon alloy; the electrolyte is a commercial polymer solid electrolyte membrane with a thickness of 100 μm; and the counter electrode is lithium metal. The specific preparation method is as follows:

[0197] Preparation of the working electrode: Ytterbium-silicon alloy, Ketjen black, and PVDF were mixed in a mass ratio of 8:1:1 and loaded onto copper foil by smearing. The smearing solvent was N-methylpyrrolidone, and the working electrode loading was 5.0-10.0 mg / cm 2 The copper foil loaded with the working electrode was cut into discs to obtain a working electrode sheet with a diameter of 10 mm. The lithium metal was cold-pressed into thin sheets and cut into discs with a diameter of 12 mm and a thickness of 50 μm to obtain a counter electrode sheet.

[0198] The cut discs were placed into the CR2032 button battery mold in the order of the counter electrode sheet, polymer solid electrolyte membrane, and working electrode sheet, and packaged at a packaging pressure of 0.5t.

[0199] (3) A lithium battery using ytterbium-silicon alloy material as a negative electrode, the specific preparation method is as follows:

[0200] The electrolyte is a commercial polymer solid electrolyte membrane with a thickness of 100μm; the negative electrode is a ytterbium-silicon alloy material; and the positive electrode is a mixture of lithium titanate, Ketjen black, and PVDF.

[0201] Preparation of the positive electrode: Lithium titanate, Ketjen black, and PVDF were mixed in a mass ratio of 8:1:1. The working electrode material was loaded onto aluminum foil by smearing. The smearing solvent was N-methylpyrrolidone, and the working electrode loading was 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode was cut into discs to obtain positive electrode sheets with a diameter of 10 mm.

[0202] Preparation of the negative electrode: Ytterbium-silicon alloy, Ketjen black, and PVDF were mixed in a mass ratio of 8:1:1 and loaded onto copper foil by smearing. The solvent for the smearing was N-methylpyrrolidone, and the negative electrode loading was 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode was cut into discs to obtain a negative electrode sheet with a diameter of 10 mm.

[0203] Place the cut discs into the CR2032 button battery mold in the order of negative electrode sheet, polymer solid electrolyte membrane, and positive electrode sheet, and package them with a packaging pressure of 0.5t.

[0204] Comparative Example 10

[0205] (1) The preparation method of ytterbium-silicon rare earth silicon alloy material is as follows:

[0206] The raw materials are ytterbium powder and silicon powder. The mixture (molar ratio of ytterbium to silicon: 0.25:0.75) is mixed in ethanol, stirred for 1 hour, and vacuum-dried at 70°C for 10 hours to obtain a precursor. The precursor is then heated in a muffle furnace at 900°C for 2 hours to obtain an ytterbium-silicon alloy.

[0207] (2) A lithium half-cell is used to evaluate the battery performance of ytterbium-silicon alloy materials. The specific preparation method is the same as that of Example 10.

[0208] (3) The specific preparation method of the lithium battery using ytterbium-silicon alloy material as the negative electrode is the same as that of Example 10.

[0209] Figure 19 is the electrochemical impedance spectroscopy of the lithium battery in Example 10 (negative electrode: ytterbium-silicon alloy), Figure 20 This is the electrochemical impedance spectroscopy of the lithium battery in Comparative Example 10 (negative electrode: ytterbium-silicon alloy). Figure 19 The impedance of the electrochemical impedance spectroscopy is small, and the interface impedance is almost negligible; Figure 20 The impedance of the electrochemical impedance spectrum is large and has obvious interface impedance, which shows that the method for preparing the ytterbium-silicon alloy in Example 10 is better, and the obtained ytterbium-silicon alloy has higher compatibility with the electrolyte and faster charge diffusion.

[0210] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and all changes that come within the meaning and range of equivalents of the claims are intended to be included therein.

[0211] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a rare earth silicon alloy material, characterized in that: The steps include: S1: Mixing rare earth compound and silicon powder uniformly to obtain a precursor; S2: mixing the precursor obtained in step S1 with a reducing agent, and subjecting the mixture to a high-temperature treatment to obtain a rare earth silicon alloy containing impurities; S3: washing the rare earth silicon alloy containing impurities obtained in step S2 with a solvent to remove impurities, thereby obtaining a rare earth silicon alloy material. The atomic molar ratio of rare earth to silicon is 1-50:50-99.

2. The method for preparing a rare earth silicon alloy material according to claim 1, wherein: The rare earth is a combination of one or more elements selected from scandium, yttrium, lanthanum, cerium, chromium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium; the rare earth compound includes a combination of one or more elements selected from rare earth oxides, rare earth chlorides, rare earth bromides, rare earth iodides, and rare earth sulfides; the silicon powder is a micron-sized or nanometer-sized silicon element powder; and the reducing agent is a combination of one or more elements selected from lithium, sodium, magnesium, calcium, and carbon.

3. The method for preparing a rare earth silicon alloy material according to claim 1, wherein: The method of mixing the rare earth compound and silicon powder in step S1 is a combination of one or more of a manual grinding method, a ball milling method, and a liquid phase method.

4. The method for preparing a rare earth silicon alloy material according to claim 1, wherein: The method of mixing the precursor and the reducing agent in step S2 is a combination of one or more of manual grinding, ball milling, and melting, and the high-temperature treatment is a combination of one or more of electromagnetic induction heating, muffle furnace heating, and Joule ultrafast heating.

5. The method for preparing a rare earth silicon alloy material according to claim 1, wherein: Step S3 is specifically as follows: placing the impurity-containing rare earth silicon alloy in a solvent and stirring it for 10-60 minutes, filtering it, and repeating it 2-4 times; then placing the washed product in a vacuum environment and drying it at a temperature of 60-100°C for 5-10 hours to obtain a rare earth silicon alloy material.

6. The method for preparing a rare earth silicon alloy material according to claim 5, wherein: The solvent in step S3 includes one or more combinations of deionized water, dilute hydrochloric acid, ethanol, pyridine, acetone, tetrahydrofuran, and acetonitrile.

7. A rare earth silicon alloy material prepared by the method according to any one of claims 1 to 6.

8. The use of the rare earth silicon alloy material in a lithium battery according to claim 7, characterized in that: The lithium battery comprises a negative electrode, an electrolyte and a positive electrode, wherein the negative electrode comprises the rare earth silicon alloy material and the rare earth silicon alloy material after pre-lithium embedding.

9. The use of the rare earth silicon alloy material in a lithium battery according to claim 8, characterized in that: The electrolyte is a combination of one or more liquid electrolytes and solid electrolytes, the liquid electrolyte is a combination of one or more carbonate electrolytes and ether electrolytes, and the solid electrolyte is a combination of one or more polymer electrolytes, oxide electrolytes, sulfide electrolytes, and halide electrolytes.

10. Use of the rare earth silicon alloy material in a lithium battery according to claim 8, characterized in that: The positive electrode comprises 10%-90% of a positive electrode active material, 0-70% of an electrolyte, 0-20% of a carbon material and 0-10% of a binder, wherein the positive electrode active material is one or more combinations of a lithium-containing positive electrode and a lithium-free positive electrode, the carbon material is one or more combinations of acetylene black, Ketjen black, Super P, carbon nanotubes, graphite, graphene, soft carbon, hard carbon, activated carbon and carbon fiber, and the binder is one or more combinations of polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile and polyacrylate.

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