A high-efficiency silicon suboxide anode material and its preparation method

Abstract

This invention discloses a method for preparing a high-efficiency silicon suboxide anode material. First, metal powder and silicon suboxide material are mixed and ball-milled. The metal powder is then used to further reduce elemental silicon in the silicon oxide material, increasing the material's capacity. Next, carbon nanotubes are formed on the material surface using metal ion-induced chemical vapor deposition, improving the material's initial coulombic efficiency and cycle life. Then, a metal with better conductivity is doped into the material through a substitution reaction, further enhancing its capacity and conductivity. Finally, the high-efficiency silicon suboxide anode material is obtained through sintering. The silicon suboxide anode material prepared by this invention can effectively improve the initial coulombic efficiency and cycle life of batteries, and the process is simple and highly safe.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a high-efficiency silicon suboxide anode material and its preparation method. Background Technology

[0002] With the widespread application of lithium-ion batteries in portable electronic products, electric vehicles, and other fields, traditional graphite anode materials are no longer sufficient to meet the demand for high-energy-density lithium-ion batteries. Silicon-based anode materials, with their abundant reserves and high capacity, are considered one of the most promising next-generation lithium-ion battery anode materials. Silicon anode materials are alloy-type lithium storage anode materials, attracting widespread attention due to their extremely high theoretical specific capacity. Silicon stores lithium at room temperature (25–85℃) to form Li. 15 The Si4 alloy phase exhibits a theoretical specific capacity of up to 3579 mAh / g, and can store lithium to form Li at high temperatures (100–120 °C). 22 The Si5 alloy phase exhibits a theoretical specific capacity as high as 4200 mAh / g. Furthermore, silicon has a slightly higher lithium intercalation potential than graphite, approximately 0.2V vs. Li / Li. + This can reduce lithium plating to some extent and improve battery safety. Furthermore, silicon is abundant, has low production costs, and is environmentally friendly. However, silicon undergoes significant volume changes during lithium insertion / extraction, leading to electrode structure damage and continuous formation of the solid electrolyte intercalation (SEI) membrane. This results in poor cycle stability and low initial coulombic efficiency in silicon-based anodes, severely limiting their industrial application.

[0003] Currently, improving the initial coulombic efficiency (ICE) is mainly achieved through pre-lithiation of silicon-based anodes, including direct addition of lithium powder and electrochemical pre-lithiation, both of which can improve ICE to some extent. However, these modification methods still have many problems. At present, the pre-lithiation process suffers from high cost, complex procedures, and a risk of explosion, making it difficult to apply in actual production. Furthermore, the introduction of pre-lithiating agents can easily cause electrode structural instability, affecting the electrode's electrochemical performance. Therefore, designing and developing a silicon-based anode material that can improve ICE while maintaining electrode stability and extending cycle life is a key technology for realizing the practical application of silicon-based anode materials. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a high-efficiency silicon suboxide anode material and its preparation method.

[0005] The present invention proposes a method for preparing a high-efficiency silicon suboxide anode material, comprising the following steps:

[0006] S1. Mix and ball-mill the silicon suboxide material with metal powder and an appropriate amount of heat-removing agent to obtain material A;

[0007] S2. After mixing the material A with the metal salt solution, stir thoroughly and then dry to obtain material B;

[0008] S3. The material B is subjected to chemical vapor deposition in a mixed atmosphere of carbon source gas and inert gas, cooled and ground uniformly to obtain material C.

[0009] S4. Mix the material C with nitrate solution, appropriate amount of ammonia water and appropriate amount of reducing agent, stir and react, then separate the solid and liquid, and wash and dry the obtained solid to obtain material D.

[0010] S5. The material D is placed in an inert atmosphere for sintering, and then cooled to obtain the final product.

[0011] Preferably, the metal powder is at least one selected from magnesium powder, aluminum powder, tin powder, iron powder, antimony powder, nickel powder, cobalt powder, and zinc powder.

[0012] Preferably, the mass ratio of the silicon suboxide material to the metal powder is 2:1 to 5:1.

[0013] Preferably, the median particle size of the silicon suboxide material is 3–5 μm.

[0014] Preferably, the heat-removing agent is at least one of sodium chloride, magnesium chloride, potassium chloride, and zinc chloride.

[0015] Preferably, in S1, the mixing and ball milling time is 1 to 4 hours.

[0016] Preferably, the concentration of the metal salt solution is 0.2 mol / L to 0.5 mol / L; the metal salt in the metal salt solution is one or more of nickel nitrate, cobalt nitrate, ferric nitrate, nickel sulfate, cobalt sulfate, and ferric sulfate.

[0017] Preferably, the ratio of material A to metal salt solution is 1g:(0.5~1)mL.

[0018] Preferably, in step S2, the stirring time is 1 to 2 hours.

[0019] Preferably, the volume ratio of the inert gas to the carbon source gas is 4:1 to 1:1; the inert gas is at least one of helium, argon, and nitrogen; and the carbon source gas is at least one of methane or its homologues, acetylene or its homologues, and benzene or its homologues.

[0020] Preferably, in S3, the temperature of chemical vapor deposition is 600–800°C, and the time is 1–6 hours.

[0021] Preferably, the chemical vapor deposition is performed in a rotary kiln with a rotation speed of 0.25 r / min to 1 r / min.

[0022] Preferably, in S3, the material is ground until the D50 is 5–8 μm.

[0023] Preferably, the concentration of the nitrate solution is 0.05–0.2 mol / L; and the nitrate in the nitrate solution is at least one of silver nitrate, aluminum nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, calcium nitrate, lead nitrate, and cerium nitrate.

[0024] Preferably, the concentration of the ammonia water is 5% to 10%.

[0025] Preferably, the reducing agent is at least one of formaldehyde, acetaldehyde, and glucose.

[0026] Preferably, in step S4, the stirring reaction time is 10–30 min.

[0027] Preferably, in step S4, the acid used for pickling is at least one of hydrochloric acid, acetic acid, sulfuric acid, and citric acid, and the concentration of the acid is 5% to 10%.

[0028] Preferably, in step S4, the drying is carried out in a vacuum oven at a temperature of 80–120°C for a time of 12–16 hours.

[0029] Preferably, in S5, the sintering process includes a first sintering stage and a second sintering stage, wherein the temperature of the first sintering stage is 300-400℃ and the time is 1-3h, and the temperature of the second sintering stage is 600-800℃ and the time is 4-12h.

[0030] A high-efficiency silicon suboxide anode material is prepared by the aforementioned preparation method.

[0031] In this invention, an inert atmosphere refers to a non-reactive gas atmosphere, and an inert gas refers to a non-reactive gas. Preferably, the non-reactive gas is at least one of nitrogen, argon, and helium.

[0032] The beneficial effects of this invention are as follows:

[0033] The method of this invention first involves ball milling a mixture of metal powder and silicon suboxide material to reduce more elemental silicon in the silicon suboxide material, thereby increasing the material's capacity. However, increasing the elemental silicon content can exacerbate the volume expansion effect, leading to a significant decrease in cycle performance. Therefore, this invention introduces metal ions into the material followed by a chemical vapor deposition (CVD) reaction. The metal ions can induce the formation of carbon nanotubes on the material surface, creating a conductive network that improves conductivity and limits volume expansion, thus improving cycle performance. Finally, this invention incorporates a metal with better conductivity into the material through a displacement reaction using nitrates, ammonia, and a reducing agent, further enhancing the material's capacity and conductivity. The silicon suboxide anode material prepared by this method can significantly improve the initial coulombic efficiency and cycle life of batteries. Furthermore, the process is simple and safe, which is beneficial for the widespread application of silicon-carbon anode materials. Attached Figure Description

[0034] Figure 1 The above are the SEM test results of the silicon suboxide anode material prepared in Example 1 of this invention.

[0035] Figure 2 The charge-discharge capacity test results are shown for the silicon suboxide anode material prepared in Example 1 of this invention and the commercial SiO / C material in Comparative Example 1.

[0036] Figure 3 The cycling performance test results are shown for the silicon suboxide anode material prepared in Example 1 of this invention and the commercial SiO / C material in Comparative Example 1. Detailed Implementation

[0037] The technical solution of the present invention will now be described in detail through specific embodiments.

[0038] Example 1

[0039] Preparation of high-efficiency silicon suboxide anode materials:

[0040] S1. Add 80g of silica material with a median particle size of 3μm, 10g of magnesium powder, and 10g of sodium chloride to a planetary ball mill and mix and ball mill for 2 hours to obtain material A.

[0041] S2. Mix 100g of material A with 50mL of 0.2mol / L nickel nitrate solution, stir for 1h, and then dry in a vacuum oven at 80℃ for 12h to obtain material B.

[0042] S3. Place 50g of material B in a rotary kiln, and introduce acetylene gas and argon gas. The acetylene gas flow rate is 5L / h, and the argon gas flow rate is 5L / h. Under the condition that the kiln rotation speed is 0.5r / min, chemical vapor deposition is carried out at 800℃ for 6h. After cooling to room temperature, it is then ground in a mechanical mill until D50 is 5μm to obtain material C.

[0043] S4. Mix 50g of material C with 50mL of 0.05mol / L silver nitrate solution, 10mL of 5% ammonia solution, and 1mL of 40% acetaldehyde solution, stir and react for 1h, then filter. Wash the filter cake with 5% acetic acid for 30min, filter again, and place the filter cake in a vacuum oven to dry at 100℃ for 12h to obtain material D.

[0044] S5. Place material D in a tube furnace and sinter it at 300°C for 2 hours in an argon atmosphere, then sinter it at 800°C for 10 hours. After cooling, the material is obtained.

[0045] Example 2

[0046] Preparation of high-efficiency silicon suboxide anode materials:

[0047] S1. 70g of silica material with a median particle size of 3μm, 10g of magnesium powder, and 10g of potassium chloride are added to a planetary ball mill and mixed and ball-milled for 2 hours to obtain material A.

[0048] S2. Mix 90g of material A with 50mL of 0.3mol / L cobalt nitrate solution, stir for 1.5h, and then dry in a vacuum oven at 100℃ for 12h to obtain material B.

[0049] S3. Place 50g of material B in a rotary kiln, and introduce methane gas and argon gas. The flow rate of methane gas is 5L / h, and the flow rate of argon gas is 5L / h. Under the condition that the kiln body rotation speed is 0.5r / min, chemical vapor deposition is carried out at 700℃ for 5h. After cooling to room temperature, it is then ground in a mechanical mill until D50 is 6μm to obtain material C.

[0050] S4. Mix 50g of material C with 50mL of 0.1mol / L silver nitrate solution, 10mL of 8% ammonia solution, and 2mL of 40% acetaldehyde solution, stir and react for 1h, then filter. Wash the filter cake with 5% hydrochloric acid for 30min, filter again, and place the filter cake in a vacuum oven to dry at 120℃ for 12h to obtain material D.

[0051] S5. Place material D in a tube furnace and sinter it at 300°C for 1 hour in a nitrogen atmosphere, then sinter it at 700°C for 10 hours. After cooling, the material is obtained.

[0052] Example 3

[0053] Preparation of high-efficiency silicon suboxide anode materials:

[0054] S1. Add 60g of silica material with a median particle size of 3μm, 5g of magnesium powder, 5g of tin powder, and 10g of sodium chloride to a planetary ball mill and mix and ball mill for 3 hours to obtain material A.

[0055] S2. Mix 80g of material A with 50mL of nickel nitrate solution with a concentration of 0.4mol / L, stir for 1h, and then dry in a vacuum oven at 100℃ for 14h to obtain material B.

[0056] S3. Place 50g of material B in a rotary kiln, and introduce acetylene gas and argon gas. The acetylene gas flow rate is 5L / h, and the argon gas flow rate is 5L / h. Under the condition that the kiln rotation speed is 1r / min, chemical vapor deposition is carried out at 600℃ for 4h. After cooling to room temperature, it is then ground in a mechanical mill until D50 is 5μm to obtain material C.

[0057] S4. Mix 50g of material C with 50mL of 0.2mol / L silver nitrate solution, 10mL of 10% ammonia solution, and 1mL of 10% glucose solution, stir and react for 1h, then filter. Wash the filter cake with 5% citric acid for 1h, filter again, and place the filter cake in a vacuum oven to dry at 100℃ for 14h to obtain material D.

[0058] S5. Place material D in a tube furnace and sinter it at 400°C for 2 hours in an argon atmosphere, then sinter it at 600°C for 10 hours. After cooling, the material is obtained.

[0059] Example 4

[0060] Preparation of high-efficiency silicon suboxide anode materials:

[0061] S1. Add 80g of silica material with a median particle size of 3μm, 5g of magnesium powder, 5g of antimony powder, and 10g of potassium chloride to a planetary ball mill and mix and ball mill for 2 hours to obtain material A.

[0062] S2. Mix 100g of material A with 50mL of 0.5mol / L nickel nitrate solution, stir for 1h, and then dry in a vacuum oven at 120℃ for 12h to obtain material B.

[0063] S3. Place 50g of material B in a rotary kiln, and introduce methane gas and argon gas. The flow rate of methane gas is 5L / h, and the flow rate of argon gas is 5L / h. Under the condition that the kiln rotation speed is 0.25r / min, chemical vapor deposition is carried out at 600℃ for 6h. After cooling to room temperature, it is then ground in a mechanical mill until D50 is 6μm to obtain material C.

[0064] S4. Mix 50g of material C with 50mL of 0.1mol / L antimony nitrate solution, 10mL of 5% ammonia solution, and 2mL of 10% glucose solution. Stir and react for 1h, then filter. Wash the filter cake with 10% acetic acid for 30min, then filter again. Place the filter cake in a vacuum oven and dry at 100℃ for 16h to obtain material D.

[0065] S5. Place material D in a tube furnace and sinter it at 400°C for 1 hour in a nitrogen atmosphere, then sinter it at 800°C for 12 hours. After cooling, the material is obtained.

[0066] Comparative Example 1

[0067] Comparative Example 1 is a commercially available SiO / C material.

[0068] Comparative Example 2

[0069] Preparation of silicon suboxide anode materials:

[0070] S1. Mix 100g of silica material with a median particle size of 3μm with 50mL of nickel nitrate solution with a concentration of 0.2mol / L, stir for 1h, and then dry in a vacuum oven at 80℃ for 12h to obtain material A;

[0071] S2. Place 50g of material A in a rotary kiln, and introduce acetylene gas and argon gas. The acetylene gas flow rate is 5L / h, and the argon gas flow rate is 5L / h. Under the condition that the kiln rotation speed is 0.5r / min, chemical vapor deposition is carried out at 800℃ for 6h. After cooling to room temperature, it is then ground in a mechanical mill until D50 is 5μm to obtain material B.

[0072] S3. Mix 50g of material B with 50mL of 0.05mol / L silver nitrate solution, 10mL of 5% ammonia solution, and 1mL of 40% acetaldehyde solution, stir and react for 1h, then filter, wash the filter cake with 5% acetic acid for 30min, filter again, and place the filter cake in a vacuum oven to dry at 100℃ for 12h to obtain material C.

[0073] S4. Place material C in a tube furnace and sinter it at 300°C for 2 hours in an argon atmosphere, then sinter it at 800°C for 10 hours. After cooling, the material is obtained.

[0074] Comparative Example 3

[0075] Preparation of silicon suboxide anode materials:

[0076] S1. Add 80g of silica material with a median particle size of 3μm, 10g of magnesium powder, and 10g of sodium chloride to a planetary ball mill and mix and ball mill for 2 hours to obtain material A.

[0077] S2. Place 50g of material A in a rotary kiln, and introduce acetylene gas and argon gas. The acetylene gas flow rate is 5L / h, and the argon gas flow rate is 5L / h. Under the condition that the kiln rotation speed is 0.5r / min, chemical vapor deposition is carried out at 800℃ for 6h. After cooling to room temperature, it is then ground in a mechanical mill until D50 is 5μm to obtain material B.

[0078] S3. Mix 50g of material B with 50mL of 0.05mol / L silver nitrate solution, 10mL of 5% ammonia solution, and 1mL of 40% acetaldehyde solution, stir and react for 1h, then filter, wash the filter cake with 5% acetic acid for 30min, filter again, and place the filter cake in a vacuum oven to dry at 100℃ for 12h to obtain material C.

[0079] S4. Place material C in a tube furnace and sinter it at 300°C for 2 hours in an argon atmosphere, then sinter it at 800°C for 10 hours. After cooling, the material is obtained.

[0080] Comparative Example 4

[0081] Preparation of silicon suboxide anode materials:

[0082] S1. Add 80g of silica material with a median particle size of 3μm, 10g of magnesium powder, and 10g of sodium chloride to a planetary ball mill and mix and ball mill for 2 hours to obtain material A.

[0083] S2. Mix 100g of material A with 50mL of 0.2mol / L nickel nitrate solution, stir for 1h, and then dry in a vacuum oven at 80℃ for 12h to obtain material B.

[0084] S3. Place 50g of material B in a rotary kiln, and introduce acetylene gas and argon gas. The acetylene gas flow rate is 5L / h, and the argon gas flow rate is 5L / h. Under the condition that the kiln rotation speed is 0.5r / min, chemical vapor deposition is carried out at 800℃ for 6h. After cooling to room temperature, it is then ground in a mechanical mill until D50 is 5μm to obtain material C.

[0085] S4. Wash 50g of material C with 5% acetic acid for 30min, then filter it, and place the filter cake in a vacuum oven to dry at 100℃ for 12h to obtain material D.

[0086] S5. Place material D in a tube furnace and sinter it at 300°C for 2 hours in an argon atmosphere, then sinter it at 800°C for 10 hours. After cooling, the material is obtained.

[0087] Test case

[0088] The silicon suboxide anode material prepared in Example 1 was subjected to SEM testing, and the results are as follows: Figure 1 As shown. By Figure 1 As can be seen from the data, the silicon suboxide anode material prepared in Example 1 has relatively uniform particle size, with a particle size of approximately 5 μm.

[0089] The silicon suboxide anode materials of Examples 1-4 and Comparative Examples 2-4, and the commercial SiO / C material of Comparative Example 1 were used as anode active materials. A paste was prepared and coated according to a mass ratio of anode active material: conductive agent SP: binder LA133 of 8:1:1 to obtain CR2016 coin cells. A 1 mol / L LiPF6 EC+DMC solution was used as the electrolyte. Electrochemical performance was tested, and the results are shown in Table 1 and [Table data would be inserted here]. Figure 2-3 As shown.

[0090] Table 1

[0091]

[0092]

[0093] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-efficiency silicon suboxide anode material, characterized in that, Includes the following steps: S1. The silica material is mixed with metal powder and an appropriate amount of heat-removing agent and ball-milled to obtain material A; the heat-removing agent is at least one of sodium chloride, magnesium chloride, potassium chloride, and zinc chloride; S2. After mixing the material A with the metal salt solution, stir thoroughly and then dry to obtain material B; the metal salt in the metal salt solution is one or more of nickel nitrate, cobalt nitrate, ferric nitrate, nickel sulfate, cobalt sulfate, and ferric sulfate. S3. The material B is subjected to chemical vapor deposition in a mixed atmosphere of carbon source gas and inert gas, cooled and ground uniformly to obtain material C. S4. The material C is mixed with nitrate solution, appropriate amount of ammonia water, and appropriate amount of reducing agent, stirred and reacted, and then the solid and liquid are separated. The obtained solid material is acid washed and dried to obtain material D. In the nitrate solution, the nitrate is at least one of silver nitrate, aluminum nitrate, sodium nitrate, potassium nitrate, ammonium nitrate, calcium nitrate, lead nitrate, and cerium nitrate. The reducing agent is at least one of formaldehyde, acetaldehyde, and glucose. S5. The material D is placed in an inert atmosphere for sintering, and then cooled to obtain the final product.

2. The method for preparing the high-efficiency silicon suboxide anode material according to claim 1, characterized in that, The metal powder is at least one of magnesium powder, aluminum powder, tin powder, iron powder, antimony powder, nickel powder, cobalt powder, and zinc powder; the mass ratio of the silicon suboxide material to the metal powder is 2:1 to 5:

1.

3. The method for preparing the high-efficiency silicon suboxide anode material according to claim 1, characterized in that, In S1, the mixing and ball milling time is 1 to 4 hours.

4. The method for preparing the high-efficiency silicon suboxide anode material according to claim 1, characterized in that, The concentration of the metal salt solution is 0.2 mol / L to 0.5 mol / L.

5. The method for preparing the high-efficiency silicon suboxide anode material according to claim 1, characterized in that, The volume ratio of the inert gas to the carbon source gas is 4:1 to 1:1; the inert gas is at least one of helium, argon, and nitrogen; the carbon source gas is at least one of methane or its homologue, acetylene or its homologue, and benzene or its homologue.

6. The method for preparing the high-efficiency silicon suboxide anode material according to claim 1, characterized in that, In S3, the temperature for chemical vapor deposition is 600–800℃, and the time is 1–6 hours.

7. The method for preparing the high-efficiency silicon suboxide anode material according to claim 1, characterized in that, The concentration of the nitrate solution is 0.05–0.2 mol / L.

8. The method for preparing the high-efficiency silicon suboxide anode material according to claim 1, characterized in that, In S4, the stirring reaction time is 10–30 min.

9. The method for preparing the high-efficiency silicon suboxide anode material according to claim 1, characterized in that, In S5, sintering includes a first stage sintering and a second stage sintering. The temperature of the first stage sintering is 300-400℃ and the time is 1-3h. The temperature of the second stage sintering is 600-800℃ and the time is 4-12h.

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