A rare earth silicon alloy material, a preparation method thereof and application thereof in lithium batteries

Abstract

The application discloses a preparation method of a rare earth silicon alloy material, and comprises the following steps: S1, uniformly mixing a rare earth compound and 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 a rare earth silicon alloy containing impurities; and S3, washing the rare earth silicon alloy containing impurities obtained in the step S2 by using a solvent to remove the impurities, so as to obtain the rare earth silicon alloy material. The atom mole ratio of the rare earth to the silicon is 1-50:50-99. The rare earth silicon alloy material prepared by the reduction method can be applied to a lithium battery as a negative electrode, can inhibit the volume change of the silicon negative electrode to a certain extent, can improve the conductivity of the negative electrode, and can improve the cycle stability of the battery.

Description

TECHNICAL FIELD

[0001] The present application relates to a rare earth silicon alloy material and a preparation method thereof and application in lithium batteries, and belongs to the technical field of lithium batteries. BACKGROUND

[0002] In order to achieve the goal of "carbon peak and carbon neutral", green low-carbon industries such as wind / solar power generation, new energy vehicles, etc. are supported by China, and the development of these new energy industries requires safe, stable and high energy density energy storage devices. Among many energy storage systems, lithium batteries with long cycle life and high energy density are widely used.

[0003] A lithium battery is usually composed of a negative electrode, an electrolyte and a positive electrode. The properties of the negative electrode will affect the performance of the battery. For lithium batteries, the lithium intercalation potential of a silicon negative electrode is low, and the theoretical capacity is high, which can enable lithium batteries to achieve high energy density and has been successfully applied in lithium batteries. However, during the cycle of lithium batteries, the silicon negative electrode particles will undergo significant volume change, leading to solid-solid contact failure, silicon particle pulverization and shedding, etc., which is not conducive to the electron / ion diffusion within the electrode, and thus reduces the cycle performance of the lithium battery.

[0004] In view of the above problems, the present application is proposed. SUMMARY

[0005] In view of the deficiencies in the prior art, the purpose of the present application 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 the silicon negative electrode of lithium batteries.

[0006] The first purpose of the present application is to provide a preparation method of a rare earth silicon alloy material, comprising the following steps:

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

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

[0009] S3: using a solvent to wash the impurities from the rare earth silicon alloy containing impurities obtained in step S2 to obtain 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 one or more of a combination of single elements of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium, the rare earth compound includes one or more of a combination of rare earth oxides, rare earth chlorides, rare earth bromides, rare earth iodides, and rare earth sulfides, the silicon powder is micron or nanometer silicon single element powder, and the reducing agent is one or more of a combination of lithium, sodium, magnesium, calcium, and carbon.

[0013] In the above technical solution, the particle size of the micron silicon powder is 1-10 μm, preferably 4-6 μm, the particle size of the nanometer silicon powder is 20-200 nm, preferably 50-100 nm, and the reducing agent is one or more of a combination of block, sheet, and powder.

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

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

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

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

[0018] The electromagnetic induction heating method makes the temperature of the reaction product reach 1400-1600 ℃ and is maintained for 1-3 min; the muffle furnace heating method makes the temperature of the reaction product reach 800-1200 ℃ and is maintained for 2-10 h; and the Joule ultrafast heating method makes the temperature of the reaction product reach 1600-2000 ℃ and is maintained for 20-30 s.

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

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

[0021] A third object of the present application is to provide an application of the above 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-embedding lithium.

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

[0023] Preferably, 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, the positive electrode active material is a combination of one or more of a lithium-containing positive electrode and a lithium-free positive electrode, the carbon material is a combination of one or more of acetylene black, Ketjen black, Super P, carbon nanotubes, graphite, graphene, soft carbon, hard carbon, activated carbon, and carbon fibers, and the binder is a combination of one or more of polytetrafluoroethylene, polyvinylidene fluoride, butadiene rubber, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, and polyacrylate.

[0024] A fourth object of the present application is to provide an application of the above 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, 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-state electrolyte, and the working electrode is the rare earth silicon alloy material and the rare earth silicon alloy material after pre-embedding lithium.

[0025] Advantages of the present application:

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

[0027] Figure 1 The charge-discharge cycle performance of the lithium half-cell in Example 1 of the present application is as follows, and the working electrode is a cerium-silicon alloy.

[0028] Figure 2The charge-discharge cycle performance of the lithium half battery in the present application comparative example 1, the working electrode is magnesium-silicon alloy;

[0029] Figure 3 The SEM image of the cerium-silicon alloy material in the present application example 2;

[0030] Figure 4 The SEM image of the cerium-silicon alloy material in the present application comparative example 2;

[0031] Figure 5 The electrochemical impedance spectrum of the lithium half battery in the present application example 3, the working electrode is yttrium-silicon alloy;

[0032] Figure 6 The electrochemical impedance spectrum of the lithium half battery in the present application comparative example 3, the working electrode is tin-silicon alloy;

[0033] Figure 7 The charge-discharge curve of the lithium battery in the present application example 4, the negative electrode is yttrium-silicon alloy;

[0034] Figure 8 The charge-discharge curve of the lithium battery in the present application comparative example 4, the negative electrode is yttrium-silicon alloy;

[0035] Figure 9 The charge-discharge curve of the lithium half battery in the present application example 5, the working electrode is lanthanum-silicon alloy;

[0036] Figure 10 The charge-discharge curve of the lithium half battery in the present application comparative example 5, the working electrode is aluminum-silicon alloy;

[0037] Figure 11 The SEM image of the lanthanum-silicon alloy material in the present application example 6;

[0038] Figure 12 The SEM image of the lanthanum-silicon alloy material in the present application comparative example 6;

[0039] Figure 13 The charge-discharge curve of the lithium half battery in the present application example 7, the working electrode is gadolinium-silicon alloy;

[0040] Figure 14 The charge-discharge curve of the lithium half battery in the present application example 7, the working electrode is titanium-silicon alloy;

[0041] Figure 15 The XRD spectrum of the gadolinium-silicon alloy in the present application example 8;

[0042] Figure 16 The XRD spectrum of the gadolinium-silicon alloy in the present application comparative example 8;

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

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

[0045] Figure 19 The electrochemical impedance spectrogram of the lithium battery in Example 10 of the present application, the negative electrode is ytterbium-silicon alloy;

[0046] Figure 20 The electrochemical impedance spectrogram of the lithium battery in Comparative Example 10 of the present application, the negative electrode is ytterbium-silicon alloy. DETAILED DESCRIPTION

[0047] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application is further described below in combination with specific embodiments.

[0048] Example 1

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

[0050] The raw materials are cerium chloride, silicon powder and metal 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, the ball-milling speed is 300 r / min, and the ball-milling time is 2 h. Then, the precursor and metal lithium (the molar ratio of lithium to chlorine is 4:1) are manually ground in a mortar for 10 min, pressed into a tablet with a pressure of 4 t, and treated by electromagnetic induction heating for 2 min to remove residual metal lithium, thereby obtaining a cerium-silicon alloy containing lithium chloride impurities. Finally, the cerium-silicon alloy is placed in a pyridine solution, stirred for 20 min, and filtered, and the above steps are repeated three times to remove the lithium chloride impurities, thereby obtaining the cerium-silicon alloy material.

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

[0052] The electrolyte is a halide solid-state electrolyte (Li3YBr6), the working electrode is the pre-lithiated cerium-silicon alloy material, the preparation method is a manual grinding method, and the molar ratio of lithium to silicon is 1:1. The counter electrode is a lithium-indium alloy.

[0053] 100 mg of Li3YBr6 powder is weighed and placed in a circular mold, and a pressure of 2 t is applied to obtain an electrolyte sheet. Then, 5 mg of the pre-lithiated cerium-silicon alloy material is added to both sides of the electrolyte sheet, and a lithium-indium alloy with a diameter of 9 mm is added to the other side, and a pressure of 4 t is applied to obtain a lithium half-cell. The inner diameter of the circular mold is 10 mm.

[0054] (3) Lithium battery with cerium-silicon alloy material as negative electrode, the specific preparation method is as follows:

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

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

[0057] Comparative Example 1

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

[0059] (2) Lithium half battery with magnesium-silicon alloy material as working electrode and lithium-indium alloy as counter electrode, which is used to evaluate the battery performance of the magnesium-silicon alloy material, the difference between the preparation method and Example 1 is that the cerium-silicon alloy is replaced by the magnesium-silicon alloy.

[0060] (3) Lithium battery with magnesium-silicon alloy material as negative electrode, the difference between the preparation method and Example 1 is that the cerium-silicon alloy is replaced by the magnesium-silicon alloy.

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

[0062] Example 2

[0063] (1) The preparation method of the 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, the ball-milling speed is 300 r / min, and the ball-milling time is 2 h. Then, the precursor and metallic lithium (the molar ratio of lithium to chlorine is 4:1) are manually ground in a mortar for 10 min, tabletting is performed at 4 t, and residual metallic lithium is removed by electromagnetic induction heating for 2 min to obtain a cerium-silicon alloy containing lithium chloride impurities. Finally, the cerium-silicon alloy is placed in a pyridine solution, stirred for 10 min, and filtered to remove the lithium chloride impurities, thereby obtaining a cerium-silicon alloy material.

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

[0066] The electrolyte is a halide solid-state electrolyte (Li3YCl6), the working electrode is a pre-lithiated cerium-silicon alloy material, the preparation method is a manual grinding method, the molar ratio of lithium to silicon is 2:1, and the counter electrode is a lithium-indium alloy.

[0067] 100 mg of Li3YCl6 powder is weighed and placed in a circular mold, 2 t of pressure is applied to obtain an electrolyte sheet. Then, 5 mg of pre-lithiated cerium-silicon alloy material is added to both sides of the electrolyte sheet, and a lithium-indium alloy with a diameter of 9 mm is added to the other side, 4 t of pressure is applied to obtain a lithium half-cell. The inner diameter of the circular mold is 10 mm.

[0068] (3) A lithium battery with a cerium-silicon alloy material as a negative electrode, and the specific preparation method is as follows:

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

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

[0071] Comparative Example 2

[0072] (1) The preparation method of the 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 the silicon powder (the molar ratio of cerium to silicon is 0.05:0.95) are ball-milled to obtain a precursor, the ball-milling speed is 300 r / min, and the ball-milling time is 2 h. Then the precursor is pressed into a tablet at 4 t, and the cerium-silicon alloy is obtained by electromagnetic induction heating treatment for 2 min.

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

[0075] (3) A lithium battery with the cerium-silicon alloy material as the negative electrode, and the specific preparation method is the same as that in Example 2.

[0076] Figure 3 The SEM image of the cerium-silicon alloy material in Example 2 is shown in FIG. 1. Figure 4 The SEM image of the cerium-silicon alloy material in Comparative Example 2 is shown in FIG. 2. Figure 3 The material morphology is uniform, and the whole is a nano-level particle; Figure 4 The material morphology is not uniform, and the nano-level particles coexist with particles larger than 10 microns; it is shown that the method for preparing the cerium-silicon alloy material in Example 2 is better, and a uniform cerium-silicon alloy material can be obtained.

[0077] Example 3

[0078] (1) The preparation method of the 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 (the molar ratio of yttrium to silicon is 0.20:0.80) are ball-mixed to obtain a precursor, the ball-milling speed is 300 r / min, and the ball-milling time is 2 h. Then, the precursor and carbon powder (the molar ratio of carbon to oxygen is 1:1) are placed in a mortar and hand-ground for 10 min, and the yttrium oxide is reduced by Joule ultrafast heating of the sample (1800°C, 30 s) to obtain the yttrium-silicon alloy material.

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

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

[0082] The glass fiber separator was cut into a round piece with a diameter of 16 mm, and then soaked in the carbonate electrolyte with a volume of 200-400 μL to obtain an electrolyte / separator piece. The working electrode was prepared by mixing yttrium-silicon alloy material, acetylene black and PVDF in a mass ratio of 8:1:1, and then loading the working electrode material on a copper foil by coating. The coating solvent was N-methyl pyrrolidone, and the loading amount of the working electrode was 5.0-10.0 mg / cm 2 The copper foil loaded with the working electrode was cut into a round piece to obtain a working electrode piece with a diameter of 10 mm. The lithium metal was cold-pressed into a thin piece, cut into a round piece with a diameter of 12 mm and a thickness of 100 μm to obtain a counter electrode piece.

[0083] The cut round pieces were sequentially placed in a CR2032 button cell mold in the order of the counter electrode piece, the electrolyte / separator, and the working electrode piece, and then packaged with a packaging pressure of 0.5 t.

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

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

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

[0087] The positive electrode was prepared by mixing lithium cobaltate, acetylene black and PVDF in a mass ratio of 8:1:1, and then loading the working electrode material on an aluminum foil by coating. The coating solvent was N-methyl pyrrolidone, and the loading amount of the working electrode was 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode was cut into a round piece to obtain a positive electrode piece with a diameter of 10 mm.

[0088] The negative electrode was prepared by mixing yttrium-silicon alloy material, acetylene black and PVDF in a mass ratio of 8:1:1, and then loading the negative electrode material on a copper foil by coating. The coating solvent was N-methyl pyrrolidone, and the loading amount of the negative electrode was 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode was cut into a round piece to obtain a negative electrode piece with a diameter of 10 mm.

[0089] The cut round pieces were sequentially placed in a CR2032 button cell mold in the order of the negative electrode piece, the electrolyte / separator, and the positive electrode piece, and then packaged with a packaging pressure of 0.5 t.

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

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

[0094] Figure 5 is the electrochemical impedance spectrum of the lithium half-cell in Example 3 (working electrode: yttrium-silicon alloy), Figure 6 is the electrochemical impedance spectrum of the lithium half-cell in Comparative Example 3 (working electrode: tin-silicon alloy). Figure 5 The impedance of the electrochemical impedance spectrum is low, and the interface impedance is not obvious; Figure 6 The electrochemical impedance spectrum has a large interface impedance; it shows 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 the 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 (the molar ratio of yttrium to silicon is 0.10:0.90) are ball milled to obtain a precursor, the ball milling speed is 300r / min, and the ball milling time is 2h. Then, the precursor and carbon powder (the molar ratio of carbon to oxygen is 1:1) are placed in a mortar and hand ground for 10min. Then, the sample is heated by joule ultrafast heating (1800℃, 20s) to reduce yttrium oxide, and the yttrium-silicon alloy material can be obtained.

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

[0099] The electrolyte is a commercial ether-based electrolyte, the working electrode is a pre-embedded lithium yttrium-silicon alloy material, 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] The glass fiber separator is cut into a round piece with a diameter of 16 mm, and then soaked in an ether-based electrolyte with a volume of 200-400 μL to obtain an electrolyte / separator piece. 2 The copper foil loaded with the working electrode is cut into a round piece to obtain a working electrode piece with a diameter of 10 mm. The lithium metal is cold-pressed into a thin piece, cut into a round piece with a diameter of 12 mm and a thickness of 100 μm to obtain a counter electrode piece.

[0101] The cut round pieces are sequentially placed in a CR2032 button cell mold in the order of the counter electrode piece, the electrolyte / separator, and the working electrode piece, and packaged with a packaging pressure of 0.5 t.

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

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

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

[0105] The positive electrode is prepared by mixing lithium cobaltate, carbon nanotubes, and PVDF in a mass ratio of 8:1:1, and loading the working electrode material on an aluminum foil by coating. The coating solvent is N-methyl pyrrolidone, and the working electrode loading is 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode is cut into a round piece to obtain a positive electrode piece with a diameter of 10 mm.

[0106] The negative electrode is prepared by mixing a yttrium-silicon alloy material, carbon nanotubes, and PVDF in a mass ratio of 8:1:1, and loading the negative electrode material on a copper foil by coating. The coating solvent is N-methyl pyrrolidone, and the negative electrode loading is 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode is cut into a round piece to obtain a negative electrode piece with a diameter of 10 mm.

[0107] The cut round pieces are sequentially placed in a CR2032 button cell mold in the order of the negative electrode piece, the electrolyte / separator, and the positive electrode piece, and packaged with a packaging pressure of 0.5 t.

[0108] Comparative Example 4

[0109] (1) The preparation method of the 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 the silicon powder (molar ratio of yttrium to silicon is 0.10:0.90) are ball-milled to obtain a precursor, the ball-milling speed is 300 r / min, and the ball-milling time is 2 h. Then, the precursor is subjected to joule ultrafast heating (1800°C, 20 s) to obtain a yttrium-silicon alloy material.

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

[0112] (3) A lithium battery with the yttrium-silicon alloy material as a negative electrode, and the specific preparation method is the same as that in Example 4.

[0113] Figure 7 The charge-discharge curve of the lithium battery in Example 4 (negative electrode: yttrium-silicon alloy), Figure 8 The charge-discharge curve of the lithium battery in Comparative Example 4 (negative electrode: yttrium-silicon alloy). Figure 7 The capacity of the charge-discharge curve in Example 4 is higher and almost coincides; Figure 8 The capacity of the charge-discharge curve in Comparative Example 4 is lower and the capacity attenuation is obvious; it indicates 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 the charge diffusion.

[0114] Example 5

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

[0116] The raw materials are lanthanum chloride, silicon powder, and metallic sodium. First, the lanthanum chloride and the silicon powder (molar ratio of lanthanum to silicon is 0.02:0.98) are ball-milled to obtain a precursor, the ball-milling speed is 300 r / min, and the ball-milling time is 2 h. The precursor and excess metallic sodium (molar ratio of sodium to chlorine is 2:1) are placed in a mortar and manually ground for 10 min, tabletted at 4 t, and subjected to heating treatment in a muffle furnace for 2 h at a heating temperature of 800°C to remove the residual metallic sodium, thereby obtaining a lanthanum-silicon alloy containing sodium chloride impurities. Finally, the reaction product is placed in anhydrous ethanol, stirred for 30 min, suction filtered, and dried at 80°C under vacuum for 10 h to remove the sodium chloride impurities, thereby obtaining a lanthanum-silicon alloy material.

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

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

[0119] Weigh out 80 mg of Li7P3S 11 Powder was placed in a circular mold and subjected to a pressure of 2t to obtain an electrolyte sheet. Then, 5mg of pre-lithium-intercalated lanthanum-silicon alloy material was added to one side of the electrolyte sheet, and a pressure of 4t was applied. Next, a 9mm diameter lithium sheet was added to the other side, and a pressure of 0.5t was applied to obtain a lithium half-cell. The inner diameter of the circular mold was 10mm.

[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-lithium intercalation, and the positive electrode is NCM811 or Li7P3S. 11 A mixture of acetylene black and acetylene black in a mass ratio of 7:2.8:0.2.

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

[0123] Comparative Example 5

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

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

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

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

[0128] Example 6

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

[0130] The raw materials are lanthanum chloride, silicon powder, and metallic sodium. First, the lanthanum chloride and silicon powder (the molar ratio of lanthanum to silicon is 0.01:0.99) are ball-milled to obtain a precursor, with a ball-milling speed of 300 r / min and a ball-milling time of 2 h. Then, the precursor and excess metallic sodium (the molar ratio of sodium to chlorine is 2:1) are manually ground in a mortar for 10 min, pressed into a tablet with a pressure of 4 t, and heated in a muffle furnace for 2 h at a temperature of 800°C to remove the residual metallic sodium, thereby obtaining a lanthanum-silicon alloy containing sodium chloride impurities. Finally, the reaction product is placed in anhydrous ethanol, stirred for 20 min, filtered under suction, and dried in a vacuum oven at 80°C for 5 h to remove the sodium chloride impurities, thereby obtaining the lanthanum-silicon alloy material.

[0131] (2) A lithium half-cell with the 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, and the specific preparation method is as follows:

[0132] The electrolyte is a sulfide solid-state electrolyte (Li3PS4), the working electrode is a pre-lithiated lanthanum-silicon alloy material, the preparation method is a manual grinding method, and the molar ratio of lithium to silicon is 1:2. The counter electrode is lithium metal.

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

[0134] (3) A lithium battery with the lanthanum-silicon alloy material as the negative electrode, and the specific preparation method is as follows:

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

[0136] 80 mg of Li3PS4 powder is weighed and placed in a circular mold, and a pressure of 2 t is applied to obtain an electrolyte sheet. Then, 10 mg of the positive electrode material is added to one side of the electrolyte sheet, and 5 mg of the pre-lithiated lanthanum-silicon alloy material is added to the other side, a pressure of 4 t is applied, and a lithium battery is obtained. The inner diameter of the circular mold is 10 mm.

[0137] Comparative Example 6

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

[0139] The raw materials are lanthanum powder, silicon powder, and metallic sodium. The lanthanum powder and the silicon powder (the molar ratio of lanthanum to silicon is 0.01:0.99) are ball-milled to obtain a precursor, with a ball-milling speed of 300 r / min and a ball-milling time of 2 h. Then, the precursor is pressed into a tablet with a pressure of 4 t, and is placed in a muffle furnace for heat treatment for 10 h at a temperature of 1100°C to obtain the lanthanum-silicon alloy material.

[0140] (2) A lithium half-cell with the 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, and the specific preparation method is the same as that of Example 6.

[0141] (3) A lithium battery with the lanthanum-silicon alloy material as the negative electrode, and the specific preparation method 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 is the SEM image of the lanthanum-silicon alloy material in Comparative Example 6. Figure 11 The material particle morphology is uniform; Figure 12 The material particle morphology is not uniform; it indicates that the method for preparing the lanthanum-silicon alloy material in Example 6 is better, and a uniform lanthanum-silicon alloy material can be obtained.

[0143] Example 7

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

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

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

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

[0148] The preparation method of the working electrode: the gadolinium-silicon alloy material, Ketjenblack and PVDF are mixed in a mass ratio of 8:1:1, and the working electrode material is loaded on the copper foil by coating. The solvent for coating is N-methyl pyrrolidone, and the loading amount of the working electrode is 5.0-10.0 mg / cm 2 The copper foil loaded with the working electrode is cut into a round piece to obtain a working electrode piece with a diameter of 10 mm. The lithium metal is cold-pressed into a thin piece, cut into a round piece with a diameter of 12 mm and a thickness of 100 μm to obtain a counter electrode piece.

[0149] The cut round pieces are sequentially placed in a CR2032 button cell mold in the order of the counter electrode piece, the electrolyte / separator, and the working electrode piece, wherein 0.1 mL of ether-based electrolyte is added between the electrode piece and the electrolyte piece, and the packaging pressure is 0.5 t.

[0150] (3) The lithium battery with the gadolinium-silicon alloy material as the negative electrode is prepared by the following specific method:

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

[0152] The preparation method of the positive electrode: the lithium iron phosphate, Ketjenblack and PVDF are mixed in a mass ratio of 7:2:1, and the working electrode material is loaded on the aluminum foil by coating. The solvent for coating is N-methyl pyrrolidone, and the loading amount of the working electrode is 5.0-10.0 mg / cm 2 . The aluminum foil loaded with the positive electrode is cut into a round piece to obtain a positive electrode piece with a diameter of 10 mm.

[0153] The preparation method of the negative electrode: the gadolinium-silicon alloy material, Ketjenblack and PVDF are mixed in a mass ratio of 8:1:1, and the negative electrode material is loaded on the copper foil by coating. The solvent for coating is N-methyl pyrrolidone, and the loading amount of the negative electrode is 5.0-10.0 mg / cm 2 . The copper foil loaded with the negative electrode is cut into a round piece to obtain a negative electrode piece with a diameter of 10 mm.

[0154] The cut round pieces are sequentially placed in a CR2032 button cell mold in the order of the negative electrode piece, the electrolyte / separator, and the positive electrode piece, wherein 0.1 mL of ether-based electrolyte is added between the electrode piece and the electrolyte piece, and the packaging pressure is 0.5 t.

[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 metal lithium.

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

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

[0159] Figure 13 The charge-discharge curve of the lithium half-cell in Example 7 (working electrode: gadolinium-silicon alloy), Figure 14 The charge-discharge curve of the lithium half-cell in Comparative Example 7 (working electrode: titanium-silicon alloy). Figure 13 The capacity of the charge-discharge curve in Example 7 is higher, and the capacity decay is relatively unobvious. Figure 14 The capacity of the charge-discharge curve in Comparative Example 7 is lower, 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 the gadolinium-silicon rare earth silicon alloy material is as follows:

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

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

[0164] Preparation method of the working electrode: The gadolinium-silicon alloy material, Super P, and PVDF were mixed in a mass ratio of 8:1:1, and the working electrode material was loaded on a copper foil by coating. The coating solvent was N-methyl pyrrolidone, and the loading amount of the working electrode was 5.0-10.0mg / cm 2The copper foil loaded with the working electrode was cut into a round piece to obtain a working electrode piece with a diameter of 10 mm. The lithium metal was cold-pressed into a thin piece, cut into a round piece with a diameter of 12 mm and a thickness of 100 μm to obtain a counter electrode piece.

[0165] The cut round pieces were sequentially placed into a CR2032 button cell mold in the order of the counter electrode piece, the electrolyte / separator, and the working electrode piece, wherein 0.1 mL of the carbonate-based electrolyte was added between the electrode piece and the electrolyte piece, and the package pressure was 0.5 t.

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

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

[0168] The positive electrode was prepared in the following manner: lithium iron phosphate, Super P, and PVDF were mixed in a mass ratio of 8:1:1, and the working electrode material was loaded on an aluminum foil by coating. The coating solvent was N-methyl pyrrolidone, and the working electrode loading amount was 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode was cut into a round piece to obtain a positive electrode piece with a diameter of 10 mm.

[0169] The negative electrode was prepared in the following manner: the gadolinium-silicon alloy material, Super P, and PVDF were mixed in a mass ratio of 8:1:1, and the negative electrode material was loaded on a copper foil by coating. The coating solvent was N-methyl pyrrolidone, and the negative electrode loading amount was 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode was cut into a round piece to obtain a negative electrode piece with a diameter of 10 mm.

[0170] The cut round pieces were sequentially placed into a CR2032 button cell mold in the order of the negative electrode piece, the electrolyte / separator, and the positive electrode piece, wherein 0.1 mL of the carbonate-based electrolyte was added between the electrode piece and the electrolyte piece, and the package pressure was 0.5 t.

[0171] Comparative Example 8

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

[0173] The raw materials were gadolinium powder and silicon powder. The gadolinium powder and the silicon powder (the molar ratio of gadolinium to silicon was 0.15:0.85) were manually ground and mixed to obtain a precursor, and the grinding time was 30 min. Then, the precursor was treated by electromagnetic induction heating for 2 min to obtain a gadolinium-silicon alloy material.

[0174] (2) A lithium half-cell for evaluating the battery performance of the gadolinium-silicon alloy material, and the specific preparation method is the same as that in Example 8.

[0175] (3) A lithium battery with the gadolinium-silicon alloy material as the negative electrode, and the specific preparation method is the same as that in Example 8.

[0176] Figure 15 The XRD pattern of the gadolinium-silicon alloy material in Example 8 is as follows: Figure 16 The XRD pattern of the gadolinium-silicon alloy material in Comparative Example 8 is as follows: Figure 16 Compared with the XRD pattern of the gadolinium-silicon alloy material in Example 8, Figure 15 the impurity peak is not obvious, and the material phase is relatively pure; it is indicated that the method for preparing the gadolinium-silicon alloy material in Example 8 is better, and a gadolinium-silicon alloy material with high purity can be obtained.

[0177] Example 9

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

[0179] The raw materials are ytterbium chloride, silicon powder, and metallic sodium. First, ytterbium chloride and silicon powder (the molar ratio of ytterbium to silicon is 0.1:0.9) are mixed to obtain a precursor by a liquid phase method, the solvent is ethanol, stirring for 1 h, and vacuum drying at 80℃ for 5 h. Then, the precursor and metallic sodium (the molar ratio of sodium to chlorine is 2:1) are manually ground in a mortar for 10 min, heated in a muffle furnace for 2 h, the heating temperature is 900℃, the residual metallic sodium is removed, and a ytterbium-silicon alloy containing sodium chloride impurities is obtained. Finally, the mixture is stirred in anhydrous ethanol for 30 min, suction filtered, washed, and vacuum dried at 80℃ for 10 h to obtain the ytterbium-silicon alloy material.

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

[0181] The preparation method of the working electrode is as follows: the ytterbium-silicon alloy material, carbon nanotubes, and PVDF are mixed with a mass ratio of 8:1:1, and the working electrode material is loaded on a copper foil by the method of coating. The coating solvent is N-methyl pyrrolidone, and the loading amount of the working electrode is 5.0-10.0 mg / cm 2 . The copper foil loaded with the working electrode is cut into a round piece to obtain a working electrode piece with a diameter of 10 mm. The lithium-indium alloy is cold-pressed into a thin piece, and then cut into a round piece with a diameter of 12 mm and a thickness of 100 μm to obtain a counter electrode piece.

[0182] The cut round pieces are sequentially placed in a CR2032 button cell mold in the order of the counter electrode piece, the polymer solid-state electrolyte film, and the working electrode piece, and then packaged, and the packaging pressure is 0.5 t.

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

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

[0185] The preparation method of the positive electrode is as follows: lithium titanate, carbon nanotubes and PVDF are mixed in a mass ratio of 8:1:1, and the working electrode material is loaded on the aluminum foil by coating. The coating solvent is N-methyl pyrrolidone, and the working electrode loading amount is 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode is cut into a round piece to obtain a positive electrode piece with a diameter of 10 mm.

[0186] The preparation method of the negative electrode is as follows: ytterbium-silicon alloy material, carbon nanotubes and PVDF are mixed in a mass ratio of 8:1:1, and the negative electrode material is loaded on the copper foil by coating. The coating solvent is N-methyl pyrrolidone, and the negative electrode loading amount is 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode is cut into a round piece to obtain a negative electrode piece with a diameter of 10 mm.

[0187] The cut round piece is placed in a CR2032 button cell mold in the order of negative electrode piece, polymer solid-state electrolyte film and positive electrode piece, and packaged, and the packaging pressure is 0.5 t.

[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 iron chloride, silicon powder and metallic sodium. The ytterbium-silicon alloy is replaced by the iron-silicon alloy.

[0190] (2) A lithium half-cell for evaluating the battery performance of the 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) A lithium battery with iron-silicon alloy material as the negative electrode, the specific preparation method 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-discharge curve of the lithium battery in Example 9 (negative electrode: ytterbium-silicon alloy), Figure 18 is the charge-discharge curve of the lithium battery in Comparative Example 9 (negative electrode: iron-silicon alloy). Figure 17 The capacity of the charge-discharge curve in the middle is higher and almost coincides; Figure 18The capacity of the charge-discharge curve is low, and the capacity decay is obvious; it shows that the ytterbium-silicon alloy of example 9 can stabilize the electrode structure and promote the diffusion of charge.

[0193] Example 10

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

[0195] The raw materials are ytterbium chloride, silicon powder, and metal lithium. First, ytterbium chloride and silicon powder (the molar ratio of ytterbium to silicon is 0.25:0.75) are mixed by a liquid phase method to obtain a precursor, the solvent is ethanol, stirring for 1 h, vacuum drying at 70°C for 10 h. Then, the precursor and metal lithium (the molar ratio of lithium to chlorine is 2:1) are placed in a mortar and hand ground for 10 min, heated in a muffle furnace for 2 h, the heating temperature is 900°C, remove the residual metal lithium, obtain ytterbium-silicon alloy containing lithium chloride impurities. Finally, the mixture is placed in anhydrous ethanol and stirred for 30 min, suction filtered, washed, vacuum dried at 70°C for 10 h, to obtain ytterbium-silicon alloy material.

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

[0197] The working electrode is prepared by mixing the ytterbium-silicon alloy material, Ketjen black, and PVDF in a mass ratio of 8:1:1, and loading the working electrode material on the copper foil by coating. The coating solvent is N-methyl pyrrolidone, and the loading amount of the working electrode is 5.0-10.0 mg / cm 2 . The copper foil loaded with the working electrode is cut into a round piece to obtain a working electrode piece with a diameter of 10 mm. The lithium metal is cold-pressed into a thin sheet, cut into a round piece with a diameter of 12 mm and a thickness of 50 μm to obtain a counter electrode piece.

[0198] The cut round pieces are sequentially placed in a CR2032 button cell mold in the order of the counter electrode piece, the polymer solid-state electrolyte film, and the working electrode piece, and packaged, with a packaging pressure of 0.5 t.

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

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

[0201] Preparation method of positive electrode: lithium titanate and Ketjen black and PVDF were mixed with a mass ratio of 8:1:1, and the working electrode material was loaded on the aluminum foil by coating. The coating solvent was N-methyl pyrrolidone, and the working electrode loading was 5.0-10.0 mg / cm 2 The aluminum foil loaded with the positive electrode was cut into a round piece to obtain a positive electrode sheet with a diameter of 10 mm.

[0202] Preparation method of negative electrode: ytterbium-silicon alloy material, Ketjen black and PVDF were mixed with a mass ratio of 8:1:1, and the negative electrode material was loaded on the copper foil by coating. The coating solvent was N-methyl pyrrolidone, and the negative electrode loading was 5.0-10.0 mg / cm 2 The copper foil loaded with the negative electrode was cut into a round piece to obtain a negative electrode sheet with a diameter of 10 mm.

[0203] The cut round piece was placed in a CR2032 button cell mold in the order of negative electrode sheet, polymer solid electrolyte film, and positive electrode sheet, and was packaged with a packaging pressure of 0.5 t.

[0204] Comparative Example 10

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

[0206] The raw materials were ytterbium powder and silicon powder. The ytterbium powder and silicon powder (molar ratio of ytterbium to silicon was 0.25:0.75) were mixed, stirred in ethanol for 1 h, vacuum dried at 70°C for 10 h to obtain a precursor. Then, the precursor was heated in a muffle furnace for 2 h at a heating temperature of 900°C to obtain a ytterbium-silicon alloy material.

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

[0208] (3) A lithium battery with ytterbium-silicon alloy material as the negative electrode, and the specific preparation method was the same as that of Example 10.

[0209] Figure 19 The electrochemical impedance spectrum of the lithium battery in Example 10 (negative electrode: ytterbium-silicon alloy), Figure 20 The electrochemical impedance spectrum of the lithium battery in Comparative Example 10 (negative electrode: ytterbium-silicon alloy). Figure 19 The impedance of the electrochemical impedance spectrum in Example 10 was smaller, and the interface impedance was almost negligible; Figure 20 The impedance of the electrochemical impedance spectrum in Comparative Example 10 was larger, and had obvious interface impedance; indicating that the method for preparing the ytterbium-silicon alloy in Example 10 was better, the compatibility between the obtained ytterbium-silicon alloy and the electrolyte was higher, and the charge diffusion was faster.

[0210] The foregoing merely illustrates the principles of the application and application of its leading features. This application is not limited to the exact details shown above and described herein, and obvious modifications will occur to those skilled in the art. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and without intent that the application be limited to the subjects shown or described, the scope of the application being indicated by the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.

[0211] Furthermore, it should be understood that although the description above is based on embodiments, not every embodiment contains only one independent technical solution, and the description above is only for the sake of clarity, and those skilled in the art should understand the description as a whole, and the technical solutions in each embodiment can be combined appropriately to form other embodiments that those skilled in the art can understand.

Claims

1. A method of producing a rare earth silicon alloy material, characterized by, It comprises the following steps: S1: uniformly mixing a rare earth compound with silicon powder to obtain a precursor; S2: mixing the precursor obtained in step S1 with a reducing agent, and subjecting the mixture to high-temperature treatment to obtain a rare earth silicon alloy containing impurities; S3: using a solvent to wash the rare earth silicon alloy containing impurities obtained in step S2 to obtain a rare earth silicon alloy material. The atomic molar ratio of the rare earth to silicon is 1-50: 50-99.

2. The method of claim 1, wherein the rare earth silicon alloy material is prepared by the steps of: preparing a rare earth silicon alloy material by a method according to claim 1; and adding a rare earth element to the rare earth silicon alloy material. The rare earth is one or more of a combination of single substances of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium; the rare earth compound comprises one or more of a combination of rare earth oxides, rare earth chlorides, rare earth bromides, rare earth iodides and rare earth sulfides; the silicon powder is micron or nanometer silicon single substance powder; and the reducing agent is one or more of a combination of lithium, sodium, magnesium and calcium.

3. The method for preparing a rare earth silicon alloy material as described in claim 1, characterized in that, The method for mixing the rare earth compound with the silicon powder in step S1 is one or more of a combination of manual grinding, ball milling and liquid phase method.

4. The method for preparing a rare earth silicon alloy material as described in claim 1, characterized in that, The method for mixing the precursor with the reducing agent in step S2 is one or more of a combination of manual grinding, ball milling and melting method; and the high-temperature treatment is one or more of a combination of electromagnetic induction heating, muffle furnace heating and joule ultrafast heating.

5. The method for preparing a rare earth silicon alloy material as described in claim 1, characterized in that, Step S3 specifically comprises: stirring the rare earth silicon alloy containing impurities in a solvent, stirring for 10-60 min, suction filtration, repeating 2-4 times, then placing the washed product in a vacuum environment for drying, the temperature being 60-100℃, and the drying time being 5-10 h, to obtain the rare earth silicon alloy material.

6. The method of claim 5, wherein the rare earth silicon alloy material is prepared by the steps of: preparing a rare earth silicon alloy material by a method according to any one of claims 1 to 4; and adding a rare earth element to the rare earth silicon alloy material. The solvent in step S3 comprises one or more of a combination of deionized water, dilute hydrochloric acid, ethanol, pyridine, acetone, tetrahydrofuran and acetonitrile.

7. A method of producing a rare earth silicon alloy material, characterized by, It comprises the following steps: The raw materials are yttrium oxide, silicon powder and carbon powder; first, the yttrium oxide is ball-mixed with the silicon powder to obtain a precursor, the molar ratio of yttrium to silicon being 0.20:0.80, and the ball-milling speed being 300 r / min, the ball-milling time being 2 h; then, the precursor and the carbon powder are manually ground in a mortar for 10 min, the molar ratio of carbon to oxygen being 1:1; the sample is heated by joule ultrafast heating, the temperature being 1800℃, and the heating time being 30 s, to reduce the yttrium oxide and obtain a yttrium-silicon rare earth alloy material.

8. A method of producing a rare earth silicon alloy material, characterized by, It comprises the following steps: The raw materials are yttrium oxide, silicon powder and carbon powder; first, the yttrium oxide is ball-mixed with the silicon powder to obtain a precursor, the molar ratio of yttrium to silicon being 0.10:0.90, and the ball-milling speed being 300 r / min, the ball-milling time being 2 h; then, the precursor and the carbon powder are manually ground in a mortar for 10 min, the molar ratio of carbon to oxygen being 1:1; the sample is heated by joule ultrafast heating, the temperature being 1800℃, and the heating time being 20 s, to reduce the yttrium oxide and obtain a yttrium-silicon rare earth alloy material.

9. A rare earth silicon alloy material prepared by the method of any one of claims 1-8.

10. Use of the rare earth silicon alloy material according to claim 9 in lithium batteries, characterized in that, The lithium battery comprises a negative electrode, an electrolyte and a positive electrode, the negative electrode comprising the rare earth silicon alloy material and the pre-lithiated rare earth silicon alloy material.

11. Use of the rare earth silicon alloy material according to claim 10 in lithium batteries, characterized in that, The electrolyte is a combination of one or more of a liquid electrolyte, a solid-state electrolyte, the liquid electrolyte is a combination of one or more of a carbonate electrolyte, an ether electrolyte, the solid-state electrolyte is a combination of one or more of a polymer electrolyte, an oxide electrolyte, a sulfide electrolyte, a halide electrolyte.

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

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