Silicon-oxygen composite negative electrode material, preparation method thereof and lithium ion battery negative electrode
By introducing fast ion conductors and carbon nitride layers on the surface of silicon oxygen particles, the problems of low energy density and poor circulation performance of lithium-ion batteries are solved, and higher electrochemical performance and lower production costs are achieved.
Patent Information
- Application Number
- CN202510103482.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-22
- Publication Date
- 2025-06-03
AI Technical Summary
The energy density of existing lithium-ion batteries is close to the theoretical limit, and the volume expansion of silicon oxygen negative electrode materials during circulation leads to rupture of SEI films and low conductivity, limiting their commercial applications.
By sequentially introducing a fast ion conductor coating and a carbon nitride protective layer on the surface of silicon oxygen particles, the fast ion layer improves the ion mobility rate and conductivity, and the carbon nitride layer suppresses SEI rupture caused by volume expansion.
It significantly improves the circulation and rate performance of the negative electrode material of lithium-ion battery, extends the service life of the battery, and reduces production costs.
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Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of lithium-ion batteries, and more particularly, to a silicon-oxygen composite anode material, a preparation method thereof, and a lithium-ion battery anode. Background Art
[0002] The energy issue is one of the important issues faced by human development. Developing a clean, pollution-free, and recyclable new energy system has become an important topic explored by scientists today. Among many energy technologies, lithium-ion batteries are widely used in consumer electronics, energy storage devices, and electric vehicles due to their high energy density, good rate performance, long service life, etc., and have become a green energy storage and conversion device with great development potential at present.
[0003] With the popularization and rapid development of electric vehicles, the demand for the energy density of lithium-ion batteries by humans has increased rapidly, and it is urgent to develop lithium-ion batteries with higher energy density. Currently, commercial lithium-ion batteries mainly use artificial graphite as the anode material. The theoretical specific capacity of graphite anode material is 372 mA·h / g, and high-end graphite materials on the market can already reach 360 - 365 mA·h / g, which is approaching its theoretical limit. Therefore, the space for improving the energy density of lithium-ion batteries by anode modification is quite limited.
[0004] Under this background, both silicon-based anode materials and lithium metal anode materials have attracted much attention due to their high theoretical specific capacity. However, due to the easy formation of dendrites during the use of lithium metal anodes, which leads to serious problems such as battery safety, they cannot be commercialized in a short time. Silicon-based anodes have advantages such as high theoretical specific capacity (3580 mA·h / g), low lithium deintercalation potential (<0.5V), environmental friendliness, rich reserves, and low cost, and are considered as the next-generation high-energy density lithium-ion battery anode materials. However, the huge volume expansion of pure silicon anode materials will lead to a sharp decline in the battery cycle performance. Silicon-oxygen anode materials have relatively low volume expansion during the lithium deintercalation process due to their special structure, and thus have relatively good cycle performance. They are the most easily industrialized silicon-based anode materials. However, due to the volume expansion causing the SEI film to break and the low conductivity of this material, to a certain extent, it restricts the commercial application of silicon-oxygen materials. Currently, the mainstream solutions mainly include fast ion layer coating and carbon layer coating, etc. However, the mechanical properties of the carbon layer are poor, and the shrinkage and expansion of silicon during cycling will cause the carbon layer to break, resulting in a sharp decline in the cycle performance of the material. Summary of the Invention
[0005] The objective of the present disclosure is to provide a silicon-oxygen composite anode material, a preparation method thereof, and a lithium-ion battery anode. The silicon-oxygen composite anode material of the present disclosure sequentially introduces a fast ion conductor coating layer and a carbon nitride protection layer on the surface of silicon-oxygen particles. The fast ion layer can effectively improve the ion migration rate and conductivity; the carbon nitride layer can inhibit the rupture of the SEI caused by the volume expansion of the silicon-oxygen anode and improve the cycling performance of the material.
[0006] To achieve the above objective, the first aspect of the present disclosure provides a silicon-oxygen composite anode material, which includes silicon-oxygen composite particles with a core-shell structure; the inner core of the silicon-oxygen composite particles includes nano silicon-oxygen particles, and the outer shell includes an inner layer and an outer layer. The inner layer is a fast ion conductor layer, and the outer layer is a carbon nitride layer.
[0007] Optionally, the nano silicon-oxygen particles are SiO particles.
[0008] Optionally, the D 50 particle size of the silicon-oxygen composite material particles is 10 - 20 μm.
[0009] Optionally, the fast ion conductor layer contains alumina; the thickness of the fast ion conductor layer is 8 - 15 nm, and the thickness of the carbon nitride layer is 30 - 50 nm.
[0010] The second aspect of the present disclosure provides a preparation method of a silicon-oxygen composite anode material for making the anode of a lithium battery. The method includes the following steps: S1. Mix nano silicon-oxygen particles with an ethanol solution containing aluminum sulfate to obtain a first mixed material; dry the solid in the first mixed material to obtain first composite particles; S2. Disperse the first composite particles into a precursor solution containing an amine compound and stir to obtain a second mixed material; S3. Dry the solid in the second mixed material and perform a sintering treatment on the dried solid; Steps S1 - S3 are each independently carried out in an inert atmosphere.
[0011] Optionally, in step S1, the D 50 particle size of the nano silicon-oxygen particles is 400 - 1000 nm, and the concentration of the ethanol solution containing aluminum sulfate is 0.05 - 0.3 mol / L; In step S1, the drying is carried out under vacuum conditions, the drying temperature is 60 - 80 °C, and the time is 6 - 24 h.
[0012] Optionally, in step S2, the amine compound includes urea; the concentration of N element in the precursor solution of the amine compound is 0.1 - 1.0 mol / L; in step S2, the stirring speed is 100 - 500 rpm, and the stirring time is 2 - 24 h.
[0013] Optionally, in step S3, the sintering treatment includes first sintering and second sintering; The conditions for the first-stage sintering include: a sintering temperature of 200-300 °C, a sintering time of 2-3 h, and a heating rate of 2-10 °C / min; the conditions for the second-stage sintering include: a sintering temperature of 400-600 °C, a sintering time of 2-4 h, and a heating rate of 2-10 °C / min.
[0014] The third aspect of the present disclosure provides a silicon-oxygen composite anode material prepared by the method described in the second aspect of the present disclosure.
[0015] The fourth aspect of the present disclosure provides a negative electrode for a lithium-ion battery, including the silicon-oxygen composite anode material described in the first aspect and / or the third aspect of the present disclosure.
[0016] Through the above technical solutions, in the silicon-oxygen composite anode material of the present disclosure, a fast ion conductor layer and a carbon nitride layer are sequentially introduced on the surface of silicon-oxygen particles. The fast ion layer can effectively improve the ion migration rate and conductivity; the carbon nitride layer can inhibit the rupture of the SEI caused by the volume expansion of the silicon-oxygen anode and improve the cycling performance of the material. The preparation method of the silicon-oxygen composite anode material of the present disclosure uses nano-silicon-oxygen particles as raw materials, and through mixing, a double coating layer with a fast ion layer on the inner layer and carbon nitride on the outer layer is realized, obtaining a double-layer composite silicon-oxygen composite anode material. Compared with ordinary silicon-oxygen materials, the fast ion coating layer of the present application can effectively improve the ion migration rate and conductivity; the carbon nitride layer can inhibit the rupture of the SEI caused by the volume expansion of the silicon-oxygen anode. The silicon-oxygen composite anode material of the present disclosure has excellent electrochemical performance. The silicon-oxygen composite anode material of the present disclosure is compatible with the existing lithium-ion battery assembly system, can be directly applied to the existing lithium-ion battery system, and has a simple process, an environmentally friendly process, and low costs, which is conducive to large-scale production.
[0017] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation section. Description of the Drawings
[0018] The drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings: Figure 1 is a schematic structural diagram of the silicon-oxygen composite anode material prepared in Example 1 of the present disclosure.
[0019] Description of the Reference Numerals in the Drawings 1: silicon oxide; 2: fast ion layer; 3: carbon nitride layer. Specific Implementation Modes
[0020] The specific embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present disclosure, and are not intended to limit the present disclosure.
[0021] The first aspect of the present disclosure provides a silicon-oxygen composite anode material, which includes silicon-oxygen composite particles with a core-shell structure; as Figure 1 shown, the inner core of the silicon-oxygen composite particles includes nano-silicon-oxygen particles 1, and the outer shell includes an inner layer and an outer layer. The inner layer is a fast ion conductor layer 2, and the outer layer is a carbon nitride layer 3.
[0022] The inventors of the present disclosure have found that a core-shell structured silicon-oxygen composite anode material with a two-layer coating of a fast ion layer inner core and a carbon nitride outer shell can significantly improve the electrochemical performance of the anode material. Among them, the fast ion layer in the material can effectively improve the ion migration rate and conductivity; the carbon nitride layer can inhibit the rupture of the SEI caused by the volume expansion of the silicon-oxygen anode, greatly improving the cycle stability and rate performance of the silicon-oxygen anode material.
[0023] According to an embodiment of the present disclosure, the D 50 particle size of the silicon-oxygen composite material particles can be 10-20 μm, preferably 13-18 μm, where the D 50 particle size can be obtained by measuring the sample suspension with a laser particle size analyzer.
[0024] According to an embodiment of the present disclosure, the fast ion conductor layer contains alumina; the thickness of the fast ion conductor layer is 8-15 nm, preferably 10-12 nm, and the thickness of the carbon nitride layer is 30-50 nm, preferably 35-45 nm. Within the above thickness range, the inner layer and the outer shell of the silicon-oxygen composite anode material have a better coating and isolation effect on the nano-silicon-oxygen particles, which can prevent the SEI film from breaking caused by their expansion and further improve the conductivity. Among them, the thicknesses of the fast ion conductor layer and the carbon nitride layer refer to the thickness of the material film layer, which can be measured by focused ion beam FIB and scanning electron microscope SEM.
[0025] According to an embodiment of the present disclosure, the nano-silicon-oxygen particles are SiO particles. The silicon-oxygen anode material has a relatively low volume expansion during the lithium deintercalation and insertion process, which is beneficial to improving the cycle performance of the battery.
[0026] According to an embodiment of the present disclosure, the fast ion conductor layer contains alumina. The above embodiment is beneficial to improving the ion migration rate and conductivity.
[0027] The second aspect of the present disclosure provides a preparation method of a silicon-oxygen composite anode material for making the anode of a lithium battery, and the method includes the following steps: S1. Mix nano-silicon oxide particles with an ethanol solution containing aluminum sulfate to obtain a first mixed material; dry the solid in the first mixed material to obtain first composite particles; S2. Disperse the first composite particles into a precursor solution containing an amine compound and stir to obtain a second mixed material; S3. Dry the solid in the second mixed material and perform a sintering treatment on the dried solid; Steps S1 - S3 are each independently carried out in an inert atmosphere.
[0028] Based on the advantages of silicon-based anode materials, such as high theoretical specific capacity (3580 mA·h / g), low de-lithiation potential (<0.5 V), environmental friendliness, rich reserves, and low cost, the preparation method provided by the present disclosure enables a fast ion conductor and a carbon nitride protective layer to be coated on the surface of the silicon oxide anode material through a post-mixing sintering treatment, effectively overcoming the problems of the SEI film breaking and low conductivity caused by the volume expansion during the de-insertion / insertion process of the silicon oxide anode material, as well as the poor mechanical properties and easy breakage of the carbon layer coating and the low cycling performance of the material, and improving the ionic conductivity of the silicon oxide anode material and the stability of the SEI film. The preparation method of the present disclosure is simple to operate, low in cost, and environmentally friendly, which is conducive to large-scale production.
[0029] According to an embodiment of the present disclosure, the D 50 particle size of the nano-silicon oxide particles in step S1 is 400 - 1000 nm, preferably 500 - 700 nm, and the concentration of the ethanol solution containing aluminum sulfate is 0.05 - 0.3 mol / L, preferably 0.1 - 0.2 mol / L.
[0030] According to an embodiment of the present disclosure, in step S1, the solid in the first mixed material can be taken out by centrifugation, the drying is carried out under vacuum conditions, the drying temperature is 60 - 80 °C, preferably 70 - 75 °C, and the time is 6 - 24 h, preferably 10 - 15 h.
[0031] According to an embodiment of the present disclosure, in step S2, the stirring speed is 100 - 500 rpm, preferably 300 - 400 rpm, and the stirring time is 2 - 24 h, preferably 10 - 15 h.
[0032] According to an embodiment of the present disclosure, in step S2, the amine compound includes urea; the concentration of N element in the precursor solution of the amine compound is 0.1 - 1.0 mol / L, preferably 0.5 - 0.7 mol / L.
[0033] According to an embodiment of the present disclosure, the sintering process in step S3 includes first sintering and second sintering; the conditions for the first sintering include: the sintering temperature is 200 - 300 °C, preferably 250 - 290 °C, the sintering time is 2 - 3 h, preferably 2 - 2.5 h, and the heating rate is 2 - 10 °C / min, preferably 5 - 8 °C / min; the conditions for the second sintering include: the sintering temperature is 400 - 600 °C, preferably 480 - 550 °C, the sintering time is 2 - 4 h, preferably 2.5 - 3.2 h, and the heating rate is 2 - 10 °C / min, preferably 5 - 8 °C / min. In the above embodiment, by using segmented sintering treatment for thermal stabilization, the specific surface area of the material can be reduced, and at the same time, a coating layer is formed, effectively overcoming the problems of excessive electrolyte consumption caused by a high specific surface area and instability of the solid electrolyte interface film caused by volume expansion during the silicon cycle, and improving the first-cycle Coulomb efficiency and cycle stability of the silicon-oxygen composite anode material.
[0034] The third aspect of the present disclosure provides a silicon-oxygen composite anode material prepared by using the method described in the second aspect of the present disclosure.
[0035] The fourth aspect of the present disclosure provides a lithium-ion battery anode, comprising the silicon-oxygen composite anode material described in the first aspect and / or the third aspect of the present disclosure.
[0036] The preparation method of the silicon-oxygen composite anode material provided by the present disclosure uses commercial nano-silicon-oxygen particles as raw materials, and realizes double-layer coating of a fast ion layer and carbon nitride through mixing, avoiding the fragmentation of the carbon layer, and obtaining a double-layer composite silicon-oxygen composite anode material. Compared with ordinary silicon-oxygen materials, the fast ion coating layer in the material can effectively improve the ion migration rate and the conductivity; the carbon nitride layer can inhibit the rupture of the SEI caused by the volume expansion of the silicon-oxygen anode, and has excellent electrochemical performance. It is compatible with the existing lithium-ion battery assembly system, can be directly applied to the existing lithium-ion battery system, and has a simple process, an environmentally friendly process, and low costs, which is conducive to large-scale production.
[0037] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereby. Unless otherwise specified, the reagents used in the present disclosure are all commercially available products.
[0038] Example 1 Preparation of a silicon-oxygen anode material with a double composite layer: Add silicon monoxide to a ball mill jar, add ethanol, the rotation speed is 600 rpm / min, the ball milling time is 10 h, and after centrifugation, the ball-milled silicon monoxide is dried in vacuum at 80 °C for 10 h; the D 50 particle size of the ball-milled silicon monoxide is 500 nm; 100 g of silicon monoxide after ball milling was added to 1 L of ethanol solution, ultrasonically dispersed for 2 h, then 34 g of aluminum sulfate (concentration 0.1 mol / L) was added, stirred for 0.5 h, centrifuged, washed with water, and vacuum dried at 80 °C to obtain the first composite particles; 5 g of the first composite particles were added to 1 L of deionized water, 0.5 mol of urea (concentration of N element 1 mol / L) was added, and stirred for 2 h to obtain a mixed solution; the mixed solution was centrifuged, washed with water, vacuum dried at 80 °C, and sintered under a nitrogen atmosphere. The heating rate of the first sintering was 2.5 °C / min, the sintering temperature was 250 °C, sintered for 2 h; the sintering temperature of the second sintering was 600 °C, sintered for 2 h, and the heating rate was 2.5 °C / min to obtain a biphasic composite silicon-oxygen composite anode material.
[0039] The obtained silicon-oxygen composite anode material was tested by FIB and SEM, and the thickness of the fast ion conductor layer was 10 nm, and the thickness of the carbon nitride layer was 35 nm. The D 50 particle size of the silicon-oxygen composite material was 15 μm.
[0040] Example 2 The preparation method of the silicon-oxygen composite anode material in this example was the same as that in Example 1, except that 1.5 mol of urea was added in this example, and the concentration of N element was 3 mol / L. It was measured that the thickness of the fast ion conductor layer was 10 nm, and the thickness of the carbon nitride layer was 55 nm. The D 50 particle size of the silicon-oxygen composite material was 22 μm.
[0041] Example 3 Silicon monoxide was added to the ball mill, and ethanol was added, the rotation speed was 600 rpm / min, the ball milling time was 10 h, and the ball-milled silicon monoxide was centrifuged and vacuum dried at 80 °C for 10 h; the D 50 particle size of the ball-milled silicon monoxide was 550 nm.
[0042] 100 g of ball-milled silicon monoxide was added to 1 L of ethanol solution, ultrasonically dispersed for 2 h, then 68 g of aluminum sulfate (concentration 0.2 mol / L) was added, and stirred for 0.5 h. Centrifuged, washed with water, and vacuum dried at 80 °C to obtain the first composite particles; 5 g of the first composite particles were added to 1 L of deionized water, 0.5 mol of urea (concentration of N element 1 mol / L) was added, and stirred for 2 h to obtain a mixed solution; the mixed solution was centrifuged, washed with water, vacuum dried at 80 °C, and sintered under a nitrogen atmosphere. The heating rate of the first sintering was 2.5 °C / min, the sintering temperature was 280 °C, sintered for 2 h, the sintering temperature of the second sintering was 550 °C, sintered for 2 h, and the heating rate was 2.5 °C / min to obtain a biphasic composite silicon-oxygen composite anode material.
[0043] The obtained silicon-oxygen composite anode material was tested by FIB and SEM, and the thickness of the fast ion conductor layer was found to be 10 nm, and the thickness of the carbon nitride layer was 39 nm. The D 50 particle size of the silicon-oxygen composite material was 17 μm.
[0044] Comparative Example 1 Preparation of a silicon-oxygen anode material coated with a fast ion layer: Silicon monoxide was added to a ball mill jar, and ethanol was added. The rotation speed was 600 rpm / min, the ball milling time was 10 h, and the ball-milled silicon monoxide was centrifuged and vacuum dried at 80 °C for 10 h after centrifugation.
[0045] 100 g of the ball-milled silicon monoxide was taken and added to 1 L of an ethanol solution, ultrasonic dispersion was carried out for 2 h, and then 34 g of aluminum sulfate (concentration 0.1 mol / L) was added, and stirring was carried out for 0.5 h. After centrifugal washing and vacuum drying at 80 °C, a silicon anode material coated with a fast ion layer was obtained; the thickness of the fast ion conductor layer was 10 nm.
[0046] Comparative Example 2 Preparation of a silicon-oxygen anode material coated with carbon nitride: Silicon monoxide was added to a ball mill jar, and ethanol was added. The rotation speed was 600 rpm / min, the ball milling time was 10 h, and the ball-milled silicon monoxide was centrifuged and vacuum dried at 80 °C for 10 h after centrifugation; 5 g of the ball-milled silicon oxide was taken and added to 1 L of deionized water, and then 0.5 mol of urea was added, and stirring was carried out for 2 h to obtain a mixed solution; The mixed solution was sintered under a nitrogen atmosphere. The heating rate of the first sintering was 2.5 °C / min, the sintering temperature was 250 °C, and the sintering time was 2 h. The sintering temperature of the second sintering was 600 °C, and the sintering time was 2 h, obtaining silicon-oxygen particles coated with carbon nitride, and the thickness of the carbon nitride layer was 35 nm.
[0047] Comparative Example 3 Preparation of a silicon-carbon material coated with a double layer of a carbon layer and a fast ion layer: Silicon monoxide was added to a ball mill jar, and ethanol was added. The rotation speed was 600 rpm / min, the ball milling time was 10 h, and the ball-milled silicon powder was centrifuged and vacuum dried at 80 °C for 10 h after centrifugation; 100 g of the ball-milled silicon monoxide was taken and added to 1 L of an ethanol solution, ultrasonic dispersion was carried out for 2 h, and then 34 g of aluminum sulfate (concentration 0.1 mol / L) was added, and stirring was carried out for 0.5 h. After centrifugal washing and vacuum drying at 80 °C, composite particles containing a fast ion coating layer were obtained; 5 g of the above composite particles were taken and added to 1 L of deionized water, and 0.5 mol of hydrochloric acid dopamine was added, and stirring was carried out for 2 h to obtain second composite particles.
[0048] The second composite particles are calcined in an argon atmosphere at a heating rate of 2.5 °C / min. The temperature is raised from room temperature to 250 °C, sintered for 1 h, then raised to 600 °C and sintered for 1 h, and finally raised to 800 °C and sintered for 3 h to obtain a negative electrode material with a double-layer coating of a carbon layer and a fast ion layer.
[0049] Test examples: The positive electrode sheet, negative electrode sheet, and separator sheet are assembled into a button battery and subjected to electrochemical tests.
[0050] Separator: Use a slicer to cut a commercial separator into 16-mm separator discs for standby; Preparation of positive electrode sheet: LiFeO 4 : CMC: SBR: Conductive carbon black is mixed in deionized water at a ratio of 9:0.45:0.05:0.5. After stirring evenly, it is coated on aluminum foil and then dried at 100 °C for 2 h. The dried electrode sheet is cut into 12-mm positive electrode discs for standby.
[0051] Preparation of negative electrode sheet: The negative electrode materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are respectively mixed with conductive carbon black and PVDF in a mass ratio of negative electrode material: PVDF: conductive carbon black = 9:0.5:0.5 and added to NMP. After stirring evenly, it is coated on copper foil and then dried at 100 °C for 2 h. The dried electrode sheet is cut into 14-mm electrode discs for standby.
[0052] The cycle stability and rate performance of the prepared batteries are tested, and the test results are shown in Tables 1 and 2 in the appendix.
[0053] The test method for cycle stability refers to GB / T42260—2022; the test method for rate performance refers to GB / T42161-2022.
[0054] Table 1
[0055] As shown in Table 1, in terms of cycle stability, the stability of the composite negative electrode material of the present disclosure is better than that of the comparative examples.
[0056] Compared with Comparative Example 1 and Comparative Example 2, the composite negative electrode material of the present disclosure includes a fast ion conductor layer and a carbon nitride layer, which can relieve the volume expansion of silicon oxide, prevent particle fragmentation and contact with the electrolyte to form SEI and consume the Li source; at the same time, it can avoid the rapid rupture of silicon oxide during cycling, resulting in a sharp decrease in cycle performance. Compared with Comparative Example 3, after dozens of cycles, with the volume expansion during the lithium deintercalation process, the cycle performance of the carbon layer, the composite negative electrode material of the present disclosure includes a carbon nitride layer, and the cycle performance is better.
[0057] Table 2
[0058] As shown in Table 2, in terms of rate performance, Example 1, Comparative Example 3, and Comparative Example 1 are at the same level, and Comparative Example 2 is relatively poor. This is because Example 1, Comparative Example 3, and Comparative Example 1 all have a fast ion layer, which can effectively improve the lithium ion migration rate and enhance the rate performance. Comparative Example 2 only has carbon nitride coating, and the lithium ion transmission is slow, so the rate performance is poor. When the composite anode material of the present disclosure is used in a battery, the battery has better rate performance.
[0059] According to the data in Table 1 and Table 2, by comparing Example 1 and Example 2, the thickness of the carbon nitride layer in Example 1 is within the preferred range of the present disclosure, and the battery has better cycle stability performance.
[0060] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.
[0061] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any suitable way. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.
[0062] In addition, any combination can be made between various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, it should also be regarded as the content disclosed by the present disclosure.
Claims
1. A silicon-oxygen composite negative electrode material, characterized in that: The silicon-oxygen composite negative electrode material comprises silicon-oxygen composite particles with a core-shell structure; the core of the silicon-oxygen composite particles comprises nano silicon-oxygen particles, and the shell comprises an inner layer and an outer layer, wherein the inner layer is a fast ion conductor layer and the outer layer is a carbon nitride layer.
2. The silicon-oxygen composite negative electrode material according to claim 1, wherein: The nano silicon oxide particles are SiO particles.
3. The silicon-oxygen composite negative electrode material according to claim 1, wherein: The D 50 The particle size is 10~20μm.
4. The silicon-oxygen composite negative electrode material according to claim 1, wherein: The fast ion conductor layer comprises aluminum oxide; The thickness of the fast ion conductor layer is 8-15 nm; the thickness of the carbon nitride layer is 30-50 nm.
5. A method for preparing a silicon-oxygen composite negative electrode material, characterized in that: The method comprises the following steps: S1, mixing the nano-silicon oxide particles with an ethanol solution containing aluminum sulfate to obtain a first mixed material; drying the solid in the first mixed material to obtain first composite particles; S2, dispersing the first composite particles into a precursor solution containing an amine compound and stirring the solution to obtain a second mixed material; S3, drying the solid in the second mixed material, and sintering the dried solid; Steps S1-S3 are each independently performed in an inert atmosphere.
6. The method according to claim 5, wherein: In step S1, the D of the nano-silicon oxide particles 50 The particle size is 400-1000 nm; the concentration of the ethanol solution containing aluminum sulfate is 0.05-0.3 mol / L; In step S1, the drying is performed under vacuum conditions, the drying temperature is 60-80° C., and the drying time is 6-24 hours.
7. The method according to claim 5, wherein: In step S2, the amine compound includes urea; the concentration of N element in the precursor solution of the amine compound is 0.1-1.0 mol / L; In step S2, the stirring speed is 100-500 rpm, and the stirring time is 2-24 hours.
8. The method according to claim 5, wherein: In step S3, the sintering process includes a first sintering and a second sintering; The first sintering conditions include: sintering temperature of 200-300°C, sintering time of 2-3h, and heating rate of 2-10°C / min; The second sintering conditions include: a sintering temperature of 400-600° C., a sintering time of 2-4 hours, and a heating rate of 2-10° C. / min.
9. A silicon-oxygen composite negative electrode material prepared by the method according to any one of claims 5 to 8.
10. A negative electrode for a lithium ion battery, characterized in that: The invention comprises the silicon-oxygen composite negative electrode material as described in any one of claims 1 to 4 or claim 9.