Preparation method of pre-magnesium silicon-oxygen negative electrode material

Abstract

The invention discloses a preparation method of a pre-magnesium silicon-oxygen negative electrode material. The preparation method comprises the following steps: carrying out pore forming on a silicon-oxygen material, carrying out carbonization purification, carrying out atomization filling on a pre-magnesium solution, and carrying out CVD (Chemical Vapor Deposition) carbon coating. The pre-magnesium silicon oxide negative electrode material prepared by the preparation method has a core-shell structure, the structure of the core is porous silicon oxide, the gaps of the core and the middle core are magnesium-containing salt, the outermost layer is an amorphous carbon layer, the porous silicon oxide is used as a carrier, the uniformity of pre-magnesium is effectively controlled in an atomized gas phase pre-magnesium manner, and the performance of the negative electrode material is improved. The material can effectively compensate the loss of irreversible lithium and improve coulombic efficiency and energy density, and meanwhile, the rich pore structure of the material is beneficial to relieving volume expansion in the battery charging and discharging process, so that the cycle performance is effectively improved.

Description

Technical Field

[0001] The invention relates to the technology of lithium battery negative electrode field, and in particular to a method for preparing a pre-magnesiumized silicon oxide negative electrode material. Background Art

[0002] In recent years, with the widespread application of lithium-ion batteries, the market has increasingly higher requirements for the energy density of lithium-ion batteries. In terms of negative electrode materials, the theoretical specific capacity of traditional graphite negative electrodes is 372mAh / g, which is difficult to meet the needs of high energy density batteries. Silicon-based materials have attracted much attention due to their theoretical specific capacity of up to 4200mAh / g, but their volume expands by up to 300% during the charge and discharge process, resulting in low reversible capacity and poor cycle performance of silicon-based negative electrode materials.

[0003] Silicon oxide negative electrode materials have attracted much attention due to their high specific capacity and low volume expansion (200%), and have begun to become the main silicon-based negative electrode materials. Although the silicon dioxide in silicon oxide can alleviate the volume expansion of silicon during the lithium insertion process to a certain extent, at the same time, silicon dioxide is an inactive substance, so the presence of silicon dioxide will lead to a lower initial efficiency of silicon oxide; and, compared with the volume expansion of graphite of about 12%, the volume expansion of silicon oxide of nearly 200% also causes its poor cycle performance. Therefore, it is necessary to improve the existing silicon oxide negative electrode materials. Summary of the invention

[0004] In view of this, the present invention aims to address the deficiencies in the prior art, and its main purpose is to provide a method for preparing a pre-magnesiumized silicon oxide negative electrode material, which can effectively solve the problem of poor cycle performance of the existing silicon oxide negative electrode material.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A method for preparing a pre-magnesiumized silicon-oxygen negative electrode material comprises the following steps:

[0007] (1) mixing SiO, a pore-forming agent and deionized water, wherein the mass ratio of SiO, the pore-forming agent and the deionized water is 1:(1-5):1, to obtain treated SiO;

[0008] (2) carbonizing the treated SiO obtained in step (1) at a carbonization heating rate of 5-10°C / min, a carbonization temperature of 800-1000°C, and a carbonization time of 5-10h, and then drying and purifying to obtain pore-forming SiO;

[0009] (3) passing the pre-magnesiumized solution through a pressurizing device and atomizing it into a gas state to obtain an atomized gas;

[0010] (4) placing the pore-forming SiO2 obtained in step (2) into a spray stirring reactor, and releasing the atomized gas obtained in step (3) in a suspended state, wherein the mass ratio of the pore-forming SiO2 to the pre-magnesium solvent is 1:

[0011] (0.1-0.3), to obtain a pre-magnesiumized silicon-oxygen precursor;

[0012] (5) The pre-magnesiumized silicon oxide precursor obtained in step (4) is subjected to CVD carbon coating, the heating rate is 5-10°C / min, the temperature is raised to 650-900°C, the carbon source is deposited for 3-5h, and the temperature is kept for 2-6h to obtain a pre-magnesiumized silicon oxide negative electrode material.

[0013] As a preferred solution, the D50 of the SiO is 1-10 μm.

[0014] As a preferred embodiment, the pore-forming agent is at least one of polyvinyl alcohol, phenoxyethanol, polyethylene glycol, acetylene bridged benzene ring, and ammonium bicarbonate.

[0015] As a preferred embodiment, the pre-magnesiumization solution is at least one of magnesium chloride solution, magnesium oxalate solution, magnesium carbonate solution, magnesium nitrate solution, magnesium sulfate solution, magnesium ammonium phosphate solution, and ethynylmagnesium bromide solution.

[0016] As a preferred solution, the pressure of the pressurizing device is 0.02-1.8Mpa.

[0017] As a preferred embodiment, the carbon source is at least one of propylene, ethylene, acetylene, styrene, propane and toluene.

[0018] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, it can be seen from the above technical solution that:

[0019] The pre-magnesiumized silicon oxide negative electrode material prepared by the preparation method of the present invention has a core-shell structure, wherein the structure of the inner core is porous silicon oxide, the inner core voids and the middle core are magnesium salt-containing, and the outermost layer is an amorphous carbon layer. By using porous silicon oxide as a carrier and atomizing gas phase pre-magnesiumization, the uniformity of pre-magnesiumization is effectively controlled, and the irreversible lithium loss can be effectively compensated, and the coulomb efficiency and energy density can be improved. At the same time, the rich pore structure of the material is conducive to alleviating the volume expansion during the battery charging and discharging process, and effectively improves the cycle performance.

[0020] In order to more clearly illustrate the structural features and effects of the present invention, the present invention is described in detail below in conjunction with specific embodiments. DETAILED DESCRIPTION

[0021] The present invention discloses a method for preparing a pre-magnesiumized silicon-oxygen negative electrode material, which comprises the following steps:

[0022] (1) SiO2, a pore-forming agent and deionized water are mixed in a mass ratio of 1:(1-5):1 to obtain treated SiO2; wherein the D50 of the SiO2 is 1-10 μm, and the pore-forming agent is at least one of polyvinyl alcohol, phenoxyethanol, polyethylene glycol, ethynyl bridged phenyl ring and ammonium bicarbonate.

[0023] (2) Carbonizing the treated SiO obtained in step (1) at a carbonization heating rate of 5-10°C / min, a carbonization temperature of 800-1000°C, and a carbonization time of 5-10h, and then drying and purifying to obtain pore-forming SiO.

[0024] (3) passing the pre-magnesiumization solution through a pressurizing device and atomizing it into a gas to obtain an atomized gas, wherein the pre-magnesiumization solution is at least one of a magnesium chloride solution, a magnesium oxalate solution, a magnesium carbonate solution, a magnesium nitrate solution, a magnesium sulfate solution, a magnesium ammonium phosphate solution, and an ethynyl magnesium bromide solution; and the pressure of the pressurizing device is 0.02-1.8 MPa.

[0025] (4) placing the pore-forming SiO2 obtained in step (2) into a spray stirring reactor, and releasing the atomized gas obtained in step (3) in a suspended state, wherein the mass ratio of the pore-forming SiO2 to the pre-magnesium solvent is 1:

[0026] (0.1-0.3), to obtain a pre-magnesiumized silicon-oxygen precursor;

[0027] (5) The pre-magnesiumized silicon oxide precursor obtained in step (4) is subjected to CVD carbon coating, the heating rate is 5-10°C / min, the temperature is raised to 650-900°C, the carbon source is deposited for 3-5h, and the temperature is kept for 2-6h to obtain a pre-magnesiumized silicon oxide negative electrode material; the carbon source is at least one of propylene, ethylene, acetylene, styrene, propane, and toluene.

[0028] The following is a detailed description with reference to a number of embodiments and comparative examples.

[0029] Example 1

[0030] (1) SiO, a pore-forming agent, and deionized water are mixed in a mass ratio of 1:2:1 to obtain treated SiO; wherein the D50 of the SiO is 1-10 μm, and the pore-forming agent is polyvinyl alcohol.

[0031] (2) The treated SiO2 obtained in step (1) is carbonized at a carbonization heating rate of 5°C / min, a carbonization temperature of 800°C, and a carbonization time of 5h, and then dried and purified to obtain pore-forming SiO2.

[0032] (3) passing the pre-magnesiumization solution through a pressurizing device and atomizing it into a gas state to obtain an atomized gas, wherein the pre-magnesiumization solution is a magnesium chloride solution; and the pressure of the pressurizing device is 0.5 MPa.

[0033] (4) placing the pore-forming SiO2 obtained in step (2) into a spray stirring reactor, and releasing the atomized gas obtained in step (3) in a suspended state, wherein the mass ratio of the pore-forming SiO2 to the pre-magnesium solvent is 1:0.1, thereby obtaining a pre-magnesiumized silicon oxide precursor;

[0034] (5) The pre-magnesiumized silicon oxide precursor obtained in step (4) is subjected to CVD carbon coating, the heating rate is 5°C / min, the temperature is raised to 800°C, the carbon source is deposited for 3 hours, and the temperature is kept for 3 hours to obtain a pre-magnesiumized silicon oxide negative electrode material; the carbon source is propylene.

[0035] Example 2

[0036] (1) SiO2, a pore-forming agent and deionized water are mixed, wherein the mass ratio of SiO2, the pore-forming agent and the deionized water is 1:2.5:1, to obtain treated SiO2; wherein the D50 of the SiO2 is 1-10 μm, and the pore-forming agent is phenoxyethanol.

[0037] (2) The treated SiO2 obtained in step (1) is carbonized at a carbonization heating rate of 5°C / min, a carbonization temperature of 800°C, and a carbonization time of 5h, and then dried and purified to obtain pore-forming SiO2.

[0038] (3) passing the pre-magnesiumization solution through a pressurizing device and atomizing it into a gas to obtain an atomized gas, wherein the pre-magnesiumization solution is a magnesium carbonate solution; and the pressure of the pressurizing device is 0.8 MPa.

[0039] (4) placing the pore-forming SiO2 obtained in step (2) into a spray stirring reactor, and releasing the atomized gas obtained in step (3) in a suspended state, wherein the mass ratio of the pore-forming SiO2 to the pre-magnesium solvent is 1:0.15, thereby obtaining a pre-magnesiumized silicon oxide precursor;

[0040] (5) The pre-magnesiumized silicon oxide precursor obtained in step (4) is subjected to CVD carbon coating, the heating rate is 6°C / min, the temperature is raised to 900°C, the carbon source is deposited for 3 hours, and the temperature is kept for 5 hours to obtain a pre-magnesiumized silicon oxide negative electrode material; the carbon source is ethylene.

[0041] Example 3

[0042] (1) SiO, a pore-forming agent, and deionized water are mixed, wherein the mass ratio of SiO, the pore-forming agent, and the deionized water is 1:1.5:1, to obtain treated SiO; wherein the D50 of the SiO is 1-10 μm, and the pore-forming agent is polyethylene glycol.

[0043] (2) The treated SiO2 obtained in step (1) is carbonized at a carbonization heating rate of 6°C / min, a carbonization temperature of 850°C, and a carbonization time of 6h, and then dried and purified to obtain pore-forming SiO2.

[0044] (3) passing the pre-magnesiumization solution through a pressurizing device and atomizing it into a gas state to obtain an atomized gas, wherein the pre-magnesiumization solution is a magnesium carbonate solution; and the pressure of the pressurizing device is 1.2 MPa.

[0045] (4) placing the pore-forming SiO2 obtained in step (2) into a spray stirring reactor, and releasing the atomized gas obtained in step (3) in a suspended state, wherein the mass ratio of the pore-forming SiO2 to the pre-magnesium solvent is 1:0.15, thereby obtaining a pre-magnesiumized silicon oxide precursor;

[0046] (5) The pre-magnesiumized silicon oxide precursor obtained in step (4) is subjected to CVD carbon coating, the heating rate is 8°C / min, the temperature is raised to 900°C, the carbon source is deposited for 3 hours, and the temperature is kept for 5 hours to obtain a pre-magnesiumized silicon oxide negative electrode material; the carbon source is acetylene.

[0047] Example 4

[0048] (1) SiO, a pore-forming agent, and deionized water are mixed, wherein the mass ratio of SiO, the pore-forming agent, and the deionized water is 1:1:1, to obtain treated SiO; wherein the D50 of the SiO is 1-10 μm, and the pore-forming agent is a polyacetylene bridged benzene ring.

[0049] (2) The treated SiO2 obtained in step (1) is carbonized at a carbonization heating rate of 10°C / min, a carbonization temperature of 800°C, and a carbonization time of 8h, and then dried and purified to obtain pore-forming SiO2.

[0050] (3) passing the pre-magnesiumization solution through a pressurizing device and atomizing it into a gas state to obtain an atomized gas, wherein the pre-magnesiumization solution is a magnesium oxalate solution; and the pressure of the pressurizing device is 0.02 MPa.

[0051] (4) placing the pore-forming SiO2 obtained in step (2) into a spray stirring reactor, and releasing the atomized gas obtained in step (3) in a suspended state, wherein the mass ratio of the pore-forming SiO2 to the pre-magnesium solvent is 1:0.3, thereby obtaining a pre-magnesiumized silicon oxide precursor;

[0052] (5) The pre-magnesiumized silicon oxide precursor obtained in step (4) is subjected to CVD carbon coating, the heating rate is 10°C / min, the temperature is raised to 650°C, the carbon source is deposited for 4 hours, and the temperature is kept for 6 hours to obtain a pre-magnesiumized silicon oxide negative electrode material; the carbon source is styrene.

[0053] Example 5

[0054] (1) SiO, a pore-forming agent and deionized water are mixed, wherein the mass ratio of SiO, the pore-forming agent and the deionized water is 1:5:1, to obtain treated SiO; wherein the D50 of the SiO is 1-10 μm, and the pore-forming agent is ammonium bicarbonate.

[0055] (2) The treated SiO2 obtained in step (1) is carbonized at a carbonization heating rate of 9°C / min, a carbonization temperature of 1000°C, and a carbonization time of 10h, and then dried and purified to obtain pore-forming SiO2.

[0056] (3) passing the pre-magnesiumization solution through a pressurizing device and atomizing it into a gas state to obtain an atomized gas, wherein the pre-magnesiumization solution is a magnesium nitrate solution; and the pressure of the pressurizing device is 1.6 MPa.

[0057] (4) placing the pore-forming SiO2 obtained in step (2) into a spray stirring reactor, and releasing the atomized gas obtained in step (3) in a suspended state, wherein the mass ratio of the pore-forming SiO2 to the pre-magnesium solvent is 1:0.2, thereby obtaining a pre-magnesiumized silicon oxide precursor;

[0058] (5) The pre-magnesiumized silicon oxide precursor obtained in step (4) is subjected to CVD carbon coating, the heating rate is 6°C / min, the temperature is raised to 800°C, the carbon source is deposited for 5 hours, and the temperature is kept for 2 hours to obtain a pre-magnesiumized silicon oxide negative electrode material; the carbon source is propane.

[0059] Example 6

[0060] (1) SiO, a pore-forming agent and deionized water are mixed, wherein the mass ratio of SiO, the pore-forming agent and the deionized water is 1:5:1, to obtain treated SiO; wherein the D50 of the SiO is 1-10 μm, and the pore-forming agent is ammonium bicarbonate.

[0061] (2) The treated SiO2 obtained in step (1) is carbonized at a carbonization heating rate of 8°C / min, a carbonization temperature of 950°C, and a carbonization time of 7h, and then dried and purified to obtain pore-forming SiO2.

[0062] (3) passing the pre-magnesiumization solution through a pressurizing device and atomizing it into a gas state to obtain an atomized gas, wherein the pre-magnesiumization solution is an ethynyl magnesium bromide solution; and the pressure of the pressurizing device is 1.8 MPa.

[0063] (4) placing the pore-forming SiO2 obtained in step (2) into a spray stirring reactor, and releasing the atomized gas obtained in step (3) in a suspended state, wherein the mass ratio of the pore-forming SiO2 to the pre-magnesium solvent is 1:0.3, thereby obtaining a pre-magnesiumized silicon oxide precursor;

[0064] (5) The pre-magnesiumized silicon oxide precursor obtained in step (4) is subjected to CVD carbon coating, the heating rate is 9°C / min, the temperature is raised to 750°C, the carbon source is deposited for 4 hours, and the temperature is kept for 6 hours to obtain a pre-magnesiumized silicon oxide negative electrode material; the carbon source is toluene.

[0065] Comparative Example 1

[0066] (1) SiO, a pore-forming agent, and deionized water are mixed in a mass ratio of 1:2:1 to obtain treated SiO; wherein the D50 of the SiO is 1-10 μm, and the pore-forming agent is polyvinyl alcohol.

[0067] (2) The treated SiO2 obtained in step (1) is carbonized at a carbonization heating rate of 5°C / min, a carbonization temperature of 800°C, and a carbonization time of 5h, and then dried and purified to obtain pore-forming SiO2.

[0068] (3) The pore-forming SiO obtained in step (2) is subjected to CVD carbon coating, the heating rate is 5°C / min, the temperature is raised to 800°C, the carbon source is deposited for 3 hours, and the temperature is kept for 3 hours to obtain a negative electrode material; the carbon source is propylene.

[0069] Comparative Example 2

[0070] (1) SiO2, a pore-forming agent and deionized water are mixed, wherein the mass ratio of SiO2, the pore-forming agent and the deionized water is 1:2.5:1, to obtain treated SiO2; wherein the D50 of the SiO2 is 1-10 μm, and the pore-forming agent is phenoxyethanol.

[0071] (2) The treated SiO2 obtained in step (1) is carbonized at a carbonization heating rate of 5°C / min, a carbonization temperature of 800°C, and a carbonization time of 5h, and then dried and purified to obtain pore-forming SiO2.

[0072] (3) The pore-forming SiO obtained in step (2) is subjected to CVD carbon coating, the heating rate is 6°C / min, the temperature is raised to 900°C, the carbon source is deposited for 3 hours, and the temperature is kept for 5 hours to obtain a negative electrode material; the carbon source is ethylene.

[0073] In order to examine the performance of the pre-magnesiumized silicon-oxygen negative electrode material of the present invention, the above multiple embodiments and comparative examples were tested, and the test results are shown in Table 1.

[0074]

[0075] Table 1

[0076] It can be seen from the above test results that the pre-magnesiumized silicon oxide negative electrode material prepared by the preparation method of the present invention has excellent first-cycle coulombic efficiency, first-cycle reversible capacity, and cycle performance, and is significantly better than the negative electrode material that has not been pre-magnesiumized. This is due to the porous structure of silicon oxide and the uniform core-shell structure silicon oxide material prepared by the pre-magnesiumization method.

[0077] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a pre-magnesiumized silicon-oxygen negative electrode material, characterized in that: The following steps are included: (1) mixing SiO, a pore-forming agent and deionized water, wherein the mass ratio of SiO, the pore-forming agent and the deionized water is 1:(1-5):1, to obtain treated SiO; (2) carbonizing the treated SiO obtained in step (1) at a carbonization heating rate of 5-10°C / min, a carbonization temperature of 800-1000°C, and a carbonization time of 5-10h, and then drying and purifying to obtain pore-forming SiO; (3) passing the pre-magnesiumized solution through a pressurizing device and atomizing it into a gas state to obtain an atomized gas; (4) placing the pore-forming SiO obtained in step (2) into a spray stirring reactor, and releasing the atomized gas obtained in step (3) in a suspended state, wherein the mass ratio of the pore-forming SiO to the pre-magnesium solvent is 1:(0.1-0.3), thereby obtaining a pre-magnesiumized silicon oxide precursor; (5) The pre-magnesiumized silicon oxide precursor obtained in step (4) is subjected to CVD carbon coating, the heating rate is 5-10°C / min, the temperature is raised to 650-900°C, the carbon source is deposited for 3-5h, and the temperature is kept for 2-6h to obtain a pre-magnesiumized silicon oxide negative electrode material.

2. The method for preparing the pre-magnesiumized silicon-oxygen negative electrode material according to claim 1, characterized in that: The D50 of the SiO is 1-10 μm.

3. The method for preparing the pre-magnesiumized silicon-oxygen negative electrode material according to claim 1, characterized in that: The pore-forming agent is at least one of polyvinyl alcohol, phenoxyethanol, polyethylene glycol, ethynyl bridged benzene ring, and ammonium bicarbonate.

4. The method for preparing the pre-magnesiumized silicon-oxygen negative electrode material according to claim 1, characterized in that: The pre-magnesiation solution is at least one of a magnesium chloride solution, a magnesium oxalate solution, a magnesium carbonate solution, a magnesium nitrate solution, a magnesium sulfate solution, a magnesium ammonium phosphate solution, and an ethynyl magnesium bromide solution.

5. The method for preparing the pre-magnesiumized silicon-oxygen negative electrode material according to claim 1, characterized in that: The pressure of the pressurizing device is 0.02-1.8Mpa.

6. The method for preparing the pre-magnesiumized silicon-oxygen negative electrode material according to claim 1, characterized in that: The carbon source is at least one of propylene, ethylene, acetylene, styrene, propane and toluene.

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