A nano Si-RE bimetallic negative electrode material prepared from recycled silicone fly ash and a preparation method and application thereof

Abstract

The application provides a kind of recycled organosilicon fly ash preparation nano Si-RE bimetal negative electrode material and its preparation method and application, belongs to molten salt electrolysis technical field.The application utilizes ultrasonic method to organosilicon fly ash pretreatment, organosilicon fly ash after pretreatment adds a small amount of aluminum powder as molten salt electrolysis negative electrode, with the material of electrically conductive as anode, by controlling electrolysis temperature, voltage, time and other conditions in the process of molten salt electrolysis, obtain Si-RE bimetal material.The application adds a small amount of aluminum powder when preparing electrode sheet to reduce activation energy in the process of electrolysis, utilizes molten salt electrolysis to recycle organosilicon fly ash in the process of organosilicon monomer generation.Homogeneous hybridization of nanoparticle in the process of electrolysis can prevent the agglomeration of silicon, improve electronic conductivity, and the 4f orbit electron of rare earth element participates in the conduction band of silicon, reduces fermi energy level, and improves electrical conductivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of molten salt electrolysis, in particular to a nano Si-RE bimetallic negative electrode material prepared by recycling organic silicon fly ash and a preparation method and application thereof. BACKGROUND

[0002] The organic silicon industry chain is divided into four links of organic silicon raw materials, organic silicon monomers, organic silicon intermediates and organic silicon deep processing. As of the end of 2024, domestic organic silicon production capacity accounts for 76% of the global total, and the industry concentration is high. In the process of organic silicon production, three-stage cyclone is included. In each stage of cyclone, a part becomes waste contact body, and the other part is mixed in the tail gas due to fine particle size and light weight, and forms organic silicon fly ash after the tail gas is burned. At present, organic silicon fly ash is difficult to handle, therefore, it is imperative to recycle organic silicon fly ash. Silicon as a negative electrode material of lithium ion battery has the advantage of a theoretical specific capacity ten times higher than that of commercial graphite, therefore, silicon-based negative electrode is one of the important ways for the development of lithium ion battery. However, the silicon negative electrode will expand by about 300% during charging and discharging, which will cause the active material to separate and the negative electrode structure to fail, and has a great influence on the cycle life of lithium ions. Therefore, relieving the volume expansion of silicon-based negative electrode is one of the key challenges in the research of silicon negative electrode material. The volume change during charging and discharging of lithium ion battery can be relieved by preparing nano-structured silicon-based material, reducing particle breakage and electrode pulverization caused by expansion, and the gap between nano particles can effectively absorb stress, thereby prolonging the cycle life. The nano structure helps to form a stable solid electrolyte interface due to its uniform volume change, reducing the continuous decomposition of electrolyte and capacity attenuation.

[0003] The molten salt electrolysis technology is an important method for preparing silicon-based negative electrode material. The existing mainstream preparation of silicon-based material often has problems such as complicated process flow, high cost and high energy consumption, such as chemical vapor deposition, thermal shock method, spray granulation, etc., and most of the silicon sources are toxic substances such as silicon tetrachloride. Making it difficult for silicon-based negative electrode material to be widely used. The molten salt electrolysis method is simple to operate, and can directly electrolyze silicon dioxide into silicon element, and the silicon source is non-toxic substance such as silicon dioxide. If the waste material after incineration of the tail gas generated during the industrial preparation of organic silicon monomer can be recycled, not only can the waste of resources be reduced, but also the secondary utilization of organic silicon fly ash can be realized, which has important significance for the sustainable development of the silicon-based negative electrode industry. SUMMARY

[0004] The purpose of the present application is to provide a nano Si-RE bimetallic negative electrode material prepared by recycling organic silicon fly ash and a preparation method and application thereof, to solve the technical problems of resource waste of organic silicon fly ash and complicated preparation process of silicon-based negative electrode material.

[0005] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0006] The application provides a preparation method of a nano Si-RE bimetal negative material prepared from recovered organic silicon fly ash, and comprises the following steps:

[0007] S1: sequentially performing acid pickling, water washing and drying on the organic silicon fly ash to obtain a powder;

[0008] S2: adding aluminum powder into the powder to obtain a pole piece through pressing;

[0009] S3: taking the pole piece as a cathode and taking a conductive material as an anode to perform electrolysis in a chloride molten salt system to obtain an electrolysis product;

[0010] S4: sequentially performing acid pickling and drying on the electrolysis product to obtain a nano Si-RE bimetal negative material;

[0011] The chloride molten salt system contains rare earth chlorides and / or rare earth oxides, wherein RE is a rare earth element.

[0012] Further, the rare earth chlorides include one or more of cerium chloride, lanthanum chloride, yttrium chloride and neodymium chloride; the rare earth oxides include one or more of lanthanum oxide, cerium oxide, cerium sesquioxide and neodymium oxide; and the other molten salts contained in the chloride molten salt system include one or more of aluminum chloride, calcium chloride, sodium chloride, potassium chloride, zinc chloride, potassium nitrate and sodium nitrate.

[0013] Further, the acid solution used in the acid pickling in the step S1 is one or more of hydrochloric acid solution, sulfuric acid solution and hydrofluoric acid solution, the concentration of the acid solution is 1-7 mol / L, and the acid pickling time is 30-200 min.

[0014] Further, in the step S2, a binder and a pore-forming agent need to be added in the pole piece pressing, the binder includes one or more of polyvinyl alcohol, polyvinylidene fluoride, polyacrylic acid and polyimide, the pore-forming agent includes one or more of ammonium bicarbonate, ammonium carbonate and polystyrene, and the mass ratio of the binder, the pore-forming agent and the organic silicon fly ash is 1-5:2-8:10-50.

[0015] Further, the mass ratio of the aluminum powder and the organic silicon fly ash is 0.1-2:1-20.

[0016] The mass ratio of the rare earth chlorides and / or the rare earth oxides in the chloride molten salt system is 1-15:100-500.

[0017] Further, the temperature of the electrolysis is 650-1000 DEG C, the voltage of the electrolysis is 1.8-3.6 V, and the electrolysis time is 2-10 h.

[0018] The electrolysis is carried out under an inert gas atmosphere, the inert gas comprises one or more of argon, nitrogen and helium, and the flow rate of the inert gas is 10-50 ml / min.

[0019] Further, when the pole piece is used as a cathode, a molybdenum wire, a molybdenum hook, a nickel mesh, a tantalum mesh or a zirconium mesh is used to fix the cathode.

[0020] Further, the conductive material comprises a graphite rod, a glass carbon rod, a carbon fiber rod or a high-purity carbon rod.

[0021] In the step S2, the pressure of the pressing is 5-20 Mpa.

[0022] Further, in the step S4, the pickling is carried out under magnetic stirring, the acid solution used for pickling comprises one or more of a hydrochloric acid solution, a sulfuric acid solution and a hydrofluoric acid solution, the concentration of the acid solution is 1-6 mol / L, and the pickling time is 30-300 min.

[0023] The drying is vacuum drying, and the drying temperature is 50-80 DEG C.

[0024] The application further provides a nano Si-RE bimetal negative electrode material prepared by the preparation method.

[0025] The application further provides an application of the nano Si-RE bimetal negative electrode material in a lithium ion battery.

[0026] The application has the following beneficial effects:

[0027] The application provides a method for preparing a nano Si-RE bimetal negative electrode material from recycled organic silicon fly ash, which uses the organic silicon fly ash material as a raw material, adds a small amount of rare earth chloride or rare earth oxide into an original chloride molten salt system to perform electrolysis, and adds a small amount of aluminum powder when preparing a pole piece.

[0028] Based on the application, the method for preparing a nano Si-RE bimetal negative electrode material from recycled organic silicon fly ash solves the problem of recycling the organic silicon fly ash material, can effectively recycle existing silicon resources, and has certain economic value. DETAILED DESCRIPTION

[0029] Figure 1 The application provides a process flow chart of the method for preparing a nano Si-RE bimetal negative electrode material from recycled organic silicon fly ash.

[0030] Figure 2The XRD graph of the nano bimetallic Si-Ce prepared in Example 1 of the present application;

[0031] Figure 3 The SEM graph of the nano bimetallic Si-Ce prepared in Example 1 of the present application;

[0032] Figure 4 The EDS graph of the nano bimetallic Si-Ce prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0033] The present application provides a preparation method of recycling organic silicon fly ash to prepare nano Si-RE bimetallic negative electrode material, comprising the following steps:

[0034] S1: sequentially performing acid washing, water washing and drying on the organic silicon fly ash to obtain a powder;

[0035] S2: adding aluminum powder into the powder to obtain an electrode sheet by pressing;

[0036] S3: taking the electrode sheet as a cathode and taking a conductive material as an anode to perform electrolysis in a chloride molten salt system to obtain an electrolysis product;

[0037] S4: sequentially performing acid washing and drying on the electrolysis product to obtain a nano Si-RE bimetallic negative electrode material;

[0038] The chloride molten salt system contains rare earth chlorides and / or rare earth oxides, wherein RE is a rare earth element.

[0039] In the present application, the rare earth chlorides contain one or more of cerium chloride, lanthanum chloride, yttrium chloride and neodymium chloride, and preferably cerium chloride; the rare earth oxides contain one or more of lanthanum oxide, cerium oxide, cerium sesquioxide and neodymium oxide, and preferably lanthanum oxide; and the other molten salts contained in the chloride molten salt system contain one or more of aluminum chloride, calcium chloride, sodium chloride, potassium chloride, zinc chloride, potassium nitrate and sodium nitrate.

[0040] In the present application, the acid washing in step S1 is performed under ultrasonic, and the acid solution used for acid washing is one or more of hydrochloric acid solution, sulfuric acid solution and hydrofluoric acid solution, and preferably hydrochloric acid solution; the concentration of the acid solution is 1-7 mol / L, preferably 2-5 mol / L, and further preferably 3-4 mol / L; and the acid washing time is 30-200 min, and preferably 60-180 min.

[0041] In the present application, in the step S2, a binder and a pore-forming agent are added in the pressing of the pole piece, the binder comprises one or more of polyvinyl alcohol, polyvinylidene fluoride, polyacrylic acid and polyimide, and preferably polyvinyl alcohol; the pore-forming agent comprises one or more of ammonium bicarbonate, ammonium carbonate and polystyrene, and preferably ammonium bicarbonate; the mass ratio of the binder, the pore-forming agent and the organic silicon fly ash is 1-5:2-8:10-50, and preferably 1.5-3:3-6:20-35.

[0042] In the present application, the mass ratio of the aluminum powder and the organic silicon fly ash is 0.1-2:1-20, and preferably 0.8-1.2:14-17.

[0043] The mass ratio of the rare earth chloride and / or the rare earth oxide in the chloride molten salt system is 1-15:100-500, and preferably 5-10:200-400.

[0044] In the present application, the temperature of the electrolysis is 650-1000℃, preferably 700-900℃, and further preferably 750-850℃; the voltage of the electrolysis is 1.8-3.6V, preferably 2.2-3.2V, and further preferably 2.4-3.0V; and the time of the electrolysis is 2-10h, preferably 3-7h, and further preferably 4-6h.

[0045] The electrolysis is carried out in an inert gas atmosphere, the inert gas comprises one or more of argon, nitrogen and helium, and the flow rate of the inert gas is 10ml / min-50ml / min, and preferably 10ml / min-40ml / min.

[0046] In the present application, when the pole piece is used as a cathode, a molybdenum wire, a molybdenum hook, a nickel mesh, a tantalum mesh or a zirconium mesh is used to fix the cathode.

[0047] In the present application, the conductive material is preferably a graphite rod, a glassy carbon rod, a carbon fiber rod or a high-purity carbon rod.

[0048] In the step S2, the pressure of the pressing is 5-20Mpa, preferably 12-18Mpa, and further preferably 13-15Mpa.

[0049] In the present application, in the step S4, the pickling is carried out under magnetic stirring, the acid solution used in the pickling comprises one or more of a hydrochloric acid solution, a sulfuric acid solution and a hydrofluoric acid solution, and preferably a hydrochloric acid solution; the concentration of the acid solution is 1-6mol / L, preferably 2-5mol / L, and further preferably 2-4mol / L; and the time of the pickling is 30-300min, preferably 60-240min, and further preferably 120-200min.

[0050] The drying is vacuum drying, and the temperature of the drying is 50-80 DEG C, preferably 60-70 DEG C.

[0051] The application further provides the nano Si-RE bimetal negative electrode material prepared by the preparation method.

[0052] The application further provides application of the nano Si-RE bimetal negative electrode material in a lithium ion battery.

[0053] In the application, the nano Si-RE bimetal negative electrode material is used as a negative electrode material in a lithium ion battery, and the nano Si-RE bimetal negative electrode material, a conductive agent and a binder are compounded to prepare a lithium ion battery negative electrode material, and the mass ratio of the nano Si-RE bimetal negative electrode material, the conductive agent and the binder is 100-300:40-100:40-100, preferably 120-240:50-80:50-80, and further preferably 130-200:60-70:60-70.

[0054] In the application, the conductive agent comprises one or more of conductive carbon black, graphene, carbon nanotube, acetylene black and polypyrrole, and preferably is conductive carbon black.

[0055] The binder comprises one or more of sodium alginate, polyvinylidene fluoride, sodium carboxymethyl cellulose, polyacrylic acid, polyvinyl alcohol and polyvinylidene fluoride-hexafluoropropylene copolymer, and preferably is sodium alginate.

[0056] The technical solutions provided by the application are described in detail below in combination with examples, but they should not be understood as limitations to the protection scope of the application.

[0057] Example 1

[0058] A method for preparing a nano Si-RE bimetal negative electrode material from recycled silicone fly ash, the method comprising the following steps:

[0059] S1: placing the silicone fly ash in a 4 mol / L hydrochloric acid solution for ultrasonic acid washing; after the acid washing, washing with deionized water, and drying in a vacuum drying oven at a temperature of 60 DEG C to obtain a powder;

[0060] S2: adding the powder obtained in S1 to 1.2 g of aluminum powder for grinding, mixing the silicone fly ash, a binder polyvinyl alcohol and a pore-forming agent ammonium bicarbonate according to a mass ratio of 25:2.2:5.4, and preparing a pole piece under a pressure of 10 Mpa, and wrapping with a molybdenum wire as a cathode;

[0061] S3: graphite crucible as anode, S2 in the molybdenum wire wrapped silicone fly ash as the cathode, in the molten salt according to the mass ratio of NaCl: CaCl2 = 1:2, in the system, 300g of molten salt is added with 10g of anhydrous cerium chloride, under the atmosphere of argon gas at the rate of 15ml / min, heating at the rate of 3℃ / min, heated to 500℃ and kept in argon atmosphere for 100min to facilitate the removal of water in the molten salt, reduce the side reaction of molten salt electrolysis, after the end of the heat preservation, the temperature is increased to 850℃ at the rate of 3℃ / min to start electrolysis, the initial setting of the electrolysis voltage is 2.2V, with the occurrence of electrolysis reaction, adjust the electrolysis voltage, the cathode surface continuously generates nano-silicon during the electrolysis process, after 6h of electrolysis, the final product is obtained;

[0062] S4: the electrolysis product obtained in S3 is acid washed with 4mol / L HCl under magnetic stirring for 30min, then washed with deionized water, dried in a vacuum drying oven at 60℃ for 10h to obtain the final product.

[0063] Example 2

[0064] A method for recycling silicone fly ash to prepare nano Si-RE bimetallic negative electrode material, the method comprising the following steps:

[0065] S1: the silicone fly ash is placed in 4mol / L hydrochloric acid solution for ultrasonic acid washing; after acid washing, deionized water is used for washing, and the powder is obtained after drying in a vacuum drying oven at a temperature of 60℃;

[0066] S2: the powder obtained in S1 is added with 1.0g of aluminum powder for grinding, and the silicone fly ash, binder polyvinylidene fluoride and pore-forming agent ammonium carbonate are mixed according to the mass ratio of 30:2:6, then an electrode sheet is prepared under the pressure of 15Mpa, and the electrode sheet is hung on a molybdenum hook for fixing the cathode material.

[0067] S3: graphite rod as anode, S2 in the molybdenum wire wrapped silicone fly ash as the cathode, the molten salt system according to the mass ratio of NaCl: KCl: MgCl2 = 2:1:1, electrolysis in an alumina crucible, 300g of molten salt is added with 10g of praseodymium chloride, heating under the atmosphere of argon gas at the rate of 15ml / min, heating at the rate of 3℃ / min, heated to 500℃ and kept in argon atmosphere for 100min to facilitate the removal of water in the molten salt, reduce the side reaction of molten salt electrolysis, after the end of the heat preservation, the temperature is increased to 800℃ at the rate of 3℃ / min to start electrolysis, the initial setting of the electrolysis voltage is 2.4V, with the occurrence of electrolysis reaction, adjust the electrolysis voltage, the cathode surface continuously generates nano-silicon during the electrolysis process, after 6h of electrolysis, the final product is obtained;

[0068] S4: The electrolysis product obtained in S3 is subjected to acid washing with 4 mol / L H2SO4 under magnetic stirring for 1 h, then washed with deionized water, and dried in a vacuum drying oven at 60°C for 10 h to obtain the final product.

[0069] Example 3

[0070] A method for preparing a nano Si-RE bimetallic negative electrode material from recycled silicone fly ash, the method comprising the following steps:

[0071] S1: The silicone fly ash is placed in a 4 mol / L hydrochloric acid solution for ultrasonic acid washing; after acid washing, deionized water is used for washing, and the powder is obtained after drying in a vacuum drying oven at a temperature of 60°C;

[0072] S2: The powder obtained in S1 is added to 0.5 g of aluminum powder for grinding, and the silicone fly ash, binder polyacrylic acid, and pore-forming agent polystyrene are mixed in a mass ratio of 24:3:6.4, and then an electrode sheet is prepared under a pressure of 12 MPa, and a molybdenum wire is used for wrapping as a cathode;

[0073] S3: A graphite crucible is used as an anode, and the silicone fly ash wrapped with a molybdenum wire in S2 is used as a cathode, and electrolysis is carried out in a molten salt with a mass ratio of NaCl:KCl:MgCl2=2:1:1, 15 g of anhydrous lanthanum chloride is added to 300 g of molten salt, the molten salt system is heated under a nitrogen atmosphere at a rate of 20 ml / min, the heating rate is 3°C / min, heating to 500°C and holding for 100 min under argon atmosphere to remove water in the molten salt and reduce side reactions during molten salt electrolysis, after holding, the temperature is increased at a rate of 5°C / min to 750°C to start electrolysis, the initial electrolysis voltage is set to 2.4V, and the electrolysis voltage is adjusted as the electrolysis reaction proceeds, nano silicon is continuously generated on the surface of the cathode, and the final product is obtained after 4h of electrolysis;

[0074] S4: The electrolysis product obtained in S3 is subjected to acid washing with 6 mol / L HNO3 under magnetic stirring for 30 min, then washed with deionized water, and dried in a vacuum drying oven at 60°C for 12 h to obtain the final product.

[0075] Example 4

[0076] A method for preparing a nano Si-RE bimetallic negative electrode material from recycled silicone fly ash, the method comprising the following steps:

[0077] S1: The silicone fly ash is placed in a 4 mol / L hydrochloric acid solution for ultrasonic acid washing; after acid washing, deionized water is used for washing, and the powder is obtained after drying in a vacuum drying oven at a temperature of 60°C;

[0078] S2: The powder obtained in S1 is added to 3 g of aluminum powder for grinding. The organic silicon fly ash, the binder polyvinyl alcohol, and the pore-forming agent ammonium carbonate are mixed in a mass ratio of 40:4.6:8.2, and then an electrode is prepared under a pressure of 12 MPa, and the electrode is wrapped with a molybdenum wire as a cathode;

[0079] S3: A graphite crucible is used as an anode, and the organic silicon fly ash wrapped with a molybdenum wire in S2 is used as a cathode. Electrolysis is performed in a molten salt system with a mass ratio of NaCl:MgCl2=1:1. 8 g of cerium oxide is added to 300 g of the molten salt. The molten salt system is heated at a heating rate of 5 ℃ / min under a nitrogen atmosphere at a flow rate of 15 ml / min. The temperature is raised to 500 ℃, and the system is kept at this temperature for 100 min under an argon atmosphere to remove water in the molten salt and reduce side reactions during electrolysis. After the heat preservation is completed, the temperature is raised to 700 ℃ at a rate of 3 ℃ / min, and electrolysis is started. The initial electrolysis voltage is set to 2.4 V. As the electrolysis reaction proceeds, the electrolysis voltage is adjusted. During the electrolysis process, nano-silicon is continuously generated on the surface of the cathode. After 4 h of electrolysis, the final product is obtained.

[0080] S4: The electrolysis product obtained in S3 is subjected to acid washing with 6 mol / L HCl under magnetic stirring for 30 min, and then washed with deionized water. After drying in a vacuum drying oven at 60 ℃ for 12 h, the final product is obtained.

[0081] Example 5

[0082] A method for preparing a nano Si-RE bimetallic negative electrode material by recycling organic silicon fly ash, the method comprising the following steps:

[0083] S1: The organic silicon fly ash is subjected to ultrasonic acid washing in a 6 mol / L sulfuric acid solution. After acid washing, the organic silicon fly ash is washed with deionized water and dried in a vacuum drying oven at a temperature of 60 ℃ to obtain a powder;

[0084] S2: The powder obtained in S1 is added to 2.6 g of aluminum powder for grinding. The organic silicon fly ash, the binder polyvinyl alcohol, and the pore-forming agent ammonium bicarbonate are mixed in a mass ratio of 45:6:8, and then an electrode is prepared under a pressure of 12 MPa, and the electrode is wrapped with a nickel mesh as a cathode;

[0085] S3: using high-purity carbon rod as anode, using the organic silicon fly ash wrapped by molybdenum wire in S2 as cathode, using the molten salt system with mass ratio of NaCl:AlCl3=3:1, electrolyzing in the alumina crucible, adding 10g of lanthanum oxide in 300g of molten salt, heating under the argon atmosphere at a rate of 20ml / min, heating at a rate of 3℃ / min, heating to 500℃ and keeping in the argon atmosphere for 100min to facilitate the removal of water in the molten salt and reduce the side reaction during the molten salt electrolysis, after the end of the keeping, heating to 800℃ at a rate of 3℃ / min to start electrolysis, initially setting the electrolysis voltage to 2.6V, adjusting the electrolysis voltage as the electrolysis reaction occurs, continuously generating nano-silicon on the surface of the cathode during the electrolysis process, and finally obtaining the product after electrolysis for 6h;

[0086] S4: acid washing the electrolysis product obtained in S3 with 4mol / L H2SO4 under magnetic stirring for 30min, then washing with deionized water, and drying in a vacuum drying oven at 80℃ for 4h to obtain the final product.

[0087] Example 6

[0088] A method for recycling organic silicon fly ash to prepare nano Si-RE bimetallic negative electrode material, the method comprising the following steps:

[0089] S1: ultrasonic acid washing the organic silicon fly ash in 6mol / L sulfuric acid solution; after acid washing, washing with deionized water, and drying in a vacuum drying oven at a temperature of 60℃ to obtain a powder;

[0090] S2: adding 1.6g of aluminum powder to the powder obtained in S1 to grind, mixing the organic silicon fly ash, the binder polyvinylidene fluoride and the pore-forming agent ammonium bicarbonate according to the mass ratio of 34:3.4:7.2, and then making a pole piece under a pressure of 14Mpa and wrapping with a nickel mesh as a cathode;

[0091] S3: using carbon fiber rod as anode, using the organic silicon fly ash wrapped by molybdenum wire in S2 as cathode, using the molten salt system with mass ratio of KCl:FeF2=5:2, electrolyzing in the alumina crucible, adding 10g of anhydrous neodymium chloride in 300g of molten salt, heating under the argon atmosphere at a rate of 25ml / min, heating at a rate of 3℃ / min, heating to 500℃ and keeping in the argon atmosphere for 100min to facilitate the removal of water in the molten salt and reduce the side reaction during the molten salt electrolysis, after the end of the keeping, heating to 820℃ at a rate of 3℃ / min to start electrolysis, initially setting the electrolysis voltage to 2.8V, adjusting the electrolysis voltage as the electrolysis reaction occurs, continuously generating nano-silicon on the surface of the cathode during the electrolysis process, and finally obtaining the product after electrolysis for 4h;

[0092] S4: The electrolysis product obtained in S3 is treated with a mixed acid of HCl and HF under magnetic stirring, the concentration of the pickling agent is 2 mol / L, the pickling time is 1 h, then washed with deionized water, and dried in a vacuum drying oven at 80°C for 4 h to obtain the final product.

[0093] Example 7

[0094] A method for preparing a nano Si-RE bimetallic negative electrode material from recycled organic silicon fly ash, the method comprising the following steps:

[0095] S1: The organic fly ash is placed in a 6 mol / L nitric acid solution for ultrasonic pickling; after pickling, deionized water is used for washing, and the powder is obtained after drying in a vacuum drying oven at a temperature of 60°C;

[0096] S2: The powder obtained in S1 is added to 2.8 g of aluminum powder for grinding, and the organic silicon fly ash, binder polyvinyl alcohol, and pore-forming agent ammonium carbonate are mixed in a mass ratio of 42:4.4:7.4 to form a pole piece under a pressure of 16 Mpa, and a molybdenum hook is used for wrapping as a cathode;

[0097] S3: A glass carbon rod is used as an anode, and the organic silicon fly ash wrapped with a molybdenum wire in S2 is used as a cathode, a molten salt system is prepared in a mass ratio of NaBr:MnF2=1:1, electrolysis is carried out in an alumina crucible, 15 g of neodymium oxide is added to 300 g of molten salt, heating is carried out under a helium atmosphere at a rate of 30 ml / min, the heating rate is 5°C / min, heating is carried out to 500°C, and the temperature is kept constant for 80 min under an argon atmosphere to facilitate the removal of water in the molten salt and reduce side reactions during molten salt electrolysis, after the temperature is kept constant, the temperature is increased to 850°C at a rate of 3°C / min to start electrolysis, the initial electrolysis voltage is set to 2.4V, and the electrolysis voltage is adjusted as the electrolysis reaction proceeds, nano silicon is continuously generated on the surface of the cathode during electrolysis, and the final product is obtained after 4 h of electrolysis;

[0098] S4: The electrolysis product obtained in S3 is treated with a mixed acid of HNO3 and HF under magnetic stirring, the concentration of the pickling agent is 1 mol / L, the pickling time is 1 h, then washed with deionized water, and dried in a vacuum drying oven at 80°C for 6 h to obtain the final product.

[0099] Example 8

[0100] A method for preparing a nano Si-RE bimetallic negative electrode material from recycled organic silicon fly ash, the method comprising the following steps:

[0101] S1: The organic silicon fly ash is placed in a 6 mol / L nitric acid solution for ultrasonic pickling; after pickling, deionized water is used for washing, and the powder is obtained after drying in a vacuum drying oven at a temperature of 60°C;

[0102] S2: The powder obtained in S1 is added to 4.2 g of aluminum powder for grinding, and the organic silicon fly ash, the binder polyvinyl alcohol and the pore-forming agent ammonium bicarbonate are mixed in a mass ratio of 48:4.5:8.4, then an electrode sheet is prepared under a pressure of 16 Mpa, and the electrode sheet is wrapped with a molybdenum wire as a cathode;

[0103] S3: A graphite rod is used as an anode, the organic silicon fly ash wrapped with a molybdenum wire in S2 is used as a cathode, a molten salt system is prepared in a mass ratio of NaI:NiF2=1:1, electrolysis is performed in an alumina crucible, 10 g of europium oxide is added to 300 g of the molten salt, the temperature is raised at a heating rate of 5 ℃ / min under a helium atmosphere of 30 ml / min, the temperature is raised to 500 ℃, and the temperature is kept constant for 80 min under an argon atmosphere to remove water in the molten salt and reduce side reactions during electrolysis of the molten salt, and then the temperature is raised to 800 ℃ at a temperature raising rate of 3 ℃ / min to start electrolysis, an initial electrolysis voltage is set to 2.6 V, the electrolysis voltage is adjusted as the electrolysis reaction proceeds, nano silicon is continuously generated on the surface of the cathode during electrolysis, and the final product is obtained after electrolysis for 6 h;

[0104] S4: The electrolysis product obtained in S3 is washed with a mixed acid of HCl and HF under magnetic stirring, the concentration of the pickling agent is 2 mol / L, the pickling time is 1 h, then the product is washed with deionized water, and the final product is obtained after drying in a vacuum drying box at 80 ℃ for 12 h.

[0105] The nano silicon material is an ideal material for a lithium ion battery negative electrode, and has attracted attention in the field of lithium ion battery negative electrode materials. The nano silicon material prepared in Examples 1-8 is assembled into a battery: the nano Si-RE bimetal negative electrode material, the conductive agent conductive carbon black and the binder sodium alginate are compounded in a mass ratio of 70:15:15 to serve as a lithium ion battery negative electrode material, a lithium metal sheet is used as a positive electrode material, a Celgard film is used as a separator, LiPF6 in ethylene carbonate (EC) and diethyl carbonate (DEC) (in a volume ratio of 3:7) with 10 wt% of fluoroethylene carbonate (FEC) is used as an electrolyte to assemble a battery for electrochemical performance test, and the results are as shown in Table 1.

[0106] Table 1 Performance test results of the battery assembled from the nano silicon material prepared in Examples 1-8

[0107]

[0108] It can be seen from the above examples that the application provides a nano Si-RE bimetal negative electrode material prepared from recycled organic silicon fly ash and a preparation method and application thereof. Figure 2 For the XRD graph of the nano bimetal Si-Ce prepared in Example 1 of the application, it can be seen that there are obvious silicon peaks at 28.4° and 47.3°, and an obvious elemental cerium peak at 33.1°; Figure 3The SEM image of the nano bimetallic Si-Ce prepared in the embodiment 1 of the present application shows that the silicon presents a porous morphology, and the cerium exists in the form of fine fibrous and needle-like. Figure 4 The EDS image of the nano bimetallic Si-Ce prepared in the embodiment 1 of the present application shows that the elemental silicon does not form a cerium-silicon alloy with the cerium, but exists in an independent form.

[0109] The present application utilizes an ultrasonic method to pretreat the organic silicon fly ash, adds a small amount of aluminum powder as a molten salt electrolysis negative electrode to the pretreated organic silicon fly ash, uses a material with conductive performance as an anode, and obtains Si-RE bimetallic materials by controlling the electrolysis temperature, voltage, time and other conditions in the molten salt electrolysis process. The present application first utilizes ultrasonic pretreatment of the organic silicon fly ash raw material to remove impurities in the raw material, and adds a small amount of aluminum powder when preparing the electrode sheet to reduce the activation energy in the electrolysis process. The present application utilizes molten salt electrolysis to efficiently recycle the organic silicon fly ash in the generation process of the organic silicon monomer, utilizes the molten salt environment, adjusts the electrolysis voltage, and can obtain nano bimetallic Si-RE materials. The uniform hybridization of the nano particles can prevent the agglomeration of silicon, improve the electronic conductivity, the 4f orbit electrons of the rare earth elements participate in the conduction band of silicon, reduce the Fermi level, and improve the electrical conductivity.

[0110] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a nano-Si-RE bimetallic negative material from recycled silicone fly ash, characterized in that, The method comprises the following steps: S1: sequentially performing acid washing, water washing and drying on the organic silicon fly ash to obtain a powder; S2: adding aluminum powder into the powder to obtain an electrode sheet by pressing; S3: performing electrolysis on the electrode sheet as a cathode and a conductive material as an anode in a chloride molten salt system containing rare earth chlorides and / or rare earth oxides to obtain an electrolysis product; S4: sequentially performing acid washing and drying on the electrolysis product to obtain a nano Si-RE bimetallic negative electrode material; wherein RE is a rare earth element; The temperature of the electrolysis is 650-1000℃, the voltage of the electrolysis is 1.8-3.6V, and the time of the electrolysis is 2-10h; The mass ratio of the aluminum powder to the organic silicon fly ash is 0.1-2:1-20; The mass ratio of the rare earth chlorides and / or rare earth oxides in the chloride molten salt system is 1-15:100-500; The rare earth chlorides are selected from one or more of cerium chloride, lanthanum chloride, yttrium chloride and neodymium chloride; the rare earth oxides are selected from one or more of lanthanum oxide, cerium oxide, cerium sesquioxide and neodymium oxide; and the other molten salts contained in the chloride molten salt system are selected from one or more of aluminum chloride, calcium chloride, sodium chloride, potassium chloride and zinc chloride; In the step S2, a binder and a pore-forming agent need to be added in the pressing of the electrode sheet; and the electrolysis is performed in an inert gas atmosphere.

2. The production method according to claim 1, characterized by, In the step S1, the acid solution used in the acid washing is one or more of hydrochloric acid solution, sulfuric acid solution and hydrofluoric acid solution, the concentration of the acid solution is 1-7mol / L, and the time of the acid washing is 30-200min.

3. The production method according to claim 1 or 2, characterized by, The binder comprises one or more of polyvinyl alcohol, polyvinylidene fluoride, polyacrylic acid and polyimide, the pore-forming agent comprises one or more of ammonium bicarbonate, ammonium carbonate and polystyrene, and the mass ratio of the binder, the pore-forming agent and the organic silicon fly ash is 1-5:2-8:10-50.

4. The preparation method according to claim 3, characterized in that, The inert gas comprises one or more of argon, nitrogen and helium, and the flow rate of the inert gas is 10-50ml / min.

5. The preparation method according to claim 1, characterized in that, When the electrode sheet is used as a cathode, a molybdenum wire, a molybdenum hook, a nickel mesh, a tantalum mesh or a zirconium mesh is used to fix the cathode; The conductive material comprises a graphite rod, a glassy carbon rod, a carbon fiber rod or a high-purity carbon rod; In the step S2, the pressure of the pressing is 5-20Mpa.

6. The production method according to claim 1 or 5, characterized by, In the step S4, the acid washing is performed under magnetic stirring, the acid solution used in the acid washing comprises one or more of hydrochloric acid solution, sulfuric acid solution and hydrofluoric acid solution, the concentration of the acid solution is 1-6mol / L, and the time of the acid washing is 30-300min; The drying is vacuum drying, and the temperature of the drying is 50-80℃.

7. The nano Si-RE bimetallic negative electrode material prepared by the preparation method in any one of claims 1-6.

8. The application of the nano Si-RE bimetallic negative electrode material in claim 7 in a lithium ion battery.

Images