Modified silicon monoxide material, method for producing the same, and use thereof

Abstract

The application relates to the technical field of lithium ion batteries, and discloses a modified silicon monoxide material and a preparation method and application thereof. The method comprises the following steps: (1) mixing silicon monoxide and lithium stearate through ball milling to obtain a mixed precursor; (2) performing sintering treatment on the mixed precursor obtained in the step (1) in an inert atmosphere to obtain the modified silicon monoxide material; wherein the sintering treatment temperature is 200-900 DEG C. The preparation method has the advantages of simple preparation method, good uniformity, convenient regulation and control, and facilitation of large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a method for preparing modified silicon suboxide material, the modified silicon suboxide material obtained by the method, and its applications. Background Technology

[0002] With the continuous development of economies and populations worldwide, energy demand is gradually increasing, leading to the growing prominence of energy crises and air pollution in recent years. Developing new clean energy sources is one of the effective ways to solve these problems. Electric vehicles, powered primarily by lithium-ion batteries, have developed rapidly in recent years as an important vehicle for energy transformation, gradually replacing current gasoline-powered vehicles due to their economic and environmental advantages. However, low energy density power batteries remain a bottleneck. Therefore, improving battery energy density is currently the main research and development direction of the lithium battery industry.

[0003] In current lithium-ion battery material systems, traditional graphite anode materials have largely reached their theoretical specific capacity, which is insufficient to meet target requirements. Silicon, with its higher theoretical gravimetric specific capacity (4200 mAh / g at room temperature), is a highly promising high-energy-density anode material. However, silicon expands by 320% in volume after full lithium insertion, leading to various problems such as particle pulverization, severe capacity decay, and poor rate performance. Compared to silicon, silicon suboxide (SiO₂) is a more suitable high-energy-density anode material. x The material is considered a good alternative, as the in-situ generated Li2O and lithium silicate during the first lithium insertion process can buffer the volume change to some extent. However, the volume change during cycling (volume expansion of ~200% during complete lithiation) is still not negligible. At the same time, the irreversible generation of Li2O and lithium silicate in the first cycle consumes the active lithium from the cathode, which leads to the low first-cycle efficiency and is also the main problem affecting the commercialization of silicon suboxide materials. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned problems of existing silicon suboxide materials and to provide a modified silicon suboxide material, its preparation method and application. The preparation method has the advantages of simple preparation method, good uniformity, easy control and is conducive to large-scale industrial production.

[0005] Through in-depth research on silicon suboxide modification, the inventors of this invention unexpectedly discovered that by using lithium stearate as a modifier and performing sintering treatment, the disproportionation temperature of SiO can be reduced and SiO disproportionation can be promoted. This allows for the modification of silicon suboxide with lower energy consumption and further improves the tap density and electrochemical performance of the modified material.

[0006] That is, the present invention provides a method for preparing a modified silicon suboxide material, the method comprising the following steps:

[0007] (1) Silicate and lithium stearate were ball-milled to obtain a mixed precursor;

[0008] (2) The mixed precursor obtained in step (1) is sintered in an inert atmosphere to obtain modified silicon suboxide material.

[0009] The sintering temperature is 200-900℃.

[0010] Preferably, the weight ratio of silicon suboxide to lithium stearate is 1-9:1, more preferably 1-3:1.

[0011] Preferably, the silicon suboxide is silicon suboxide powder.

[0012] Preferably, the particle size D50 of the silicon suboxide is 1-10 μm.

[0013] Preferably, the ball milling mixing conditions include: a ball-to-material ratio of 5-15:1, a rotation speed of 400 rpm or higher, and a ball milling time of 2-10 hours.

[0014] Preferably, the sintering temperature is 750-850℃.

[0015] Preferably, the sintering treatment includes medium-temperature melting and high-temperature calcination, wherein the medium-temperature melting temperature is 200-400℃ and the melting time is 2-4h, and the high-temperature calcination temperature is 700-900℃ and the calcination time is 2-4h.

[0016] Preferably, the inert atmosphere is any one of nitrogen, argon, or a mixture of argon and nitrogen.

[0017] Preferably, the method further includes grinding and / or sieving the sintered product.

[0018] More preferably, the sieve used for sieving is 300-600 mesh.

[0019] A second aspect of the present invention provides a modified silicon suboxide material obtained by the preparation method of the present invention described above.

[0020] Preferably, the particle size of the modified silica suboxide material is 2-5 μm.

[0021] Preferably, the modified silicon suboxide material has a core-shell structure, with the core layer comprising silicon suboxide, silicon dioxide, and silicon, and the shell layer comprising lithium silicate and amorphous carbon.

[0022] A third aspect of the present invention provides the application of the modified silicon suboxide material of the present invention as a negative electrode material in lithium-ion batteries.

[0023] The modified silicon suboxide material of the present invention is prepared by using lithium stearate and calcining it to thermally induce the formation of lithium silicate and amorphous carbon on the surface of silicon suboxide as a shell; and using Si, SiO2, and virgin SiO as the core, which are disproportionation products of SiO. In this modified silicon suboxide material, the pre-generated lithium silicate can reduce the amount of LiO that forms during the formation of the solid electrolyte interphase (SEI) film during charging and discharging. + The consumption, and has a certain Li + Diffusion helps improve first-efficiency and rate performance; the outer pyrolysis forms an amorphous carbon coating layer, which can improve the conductivity of the material and suppress the volume expansion of SiO material, thus helping to improve rate performance and cycle performance; the introduction of lithium stearate reduces the disproportionation temperature of SiO to a certain extent, prompting SiO material to undergo ideal disproportionation reaction at non-ideal disproportionation temperature, further improving the first-efficiency performance of the material.

[0024] According to a preferred embodiment of the present invention, the sintering process includes medium-temperature melting and high-temperature calcination. The medium-temperature melting causes the molten lithium stearate to uniformly coat the surface of silicon suboxide, followed by high-temperature calcination to obtain the modified silicon suboxide material. By combining medium-temperature melting and high-temperature calcination, the tap density and electrochemical performance of the material can be further improved.

[0025] The preparation method of this invention can promote the disproportionation of SiO. The modified silicon suboxide anode material prepared by this method can be well integrated into the current graphite anode system, and exhibits good overall performance after being combined with graphite. The preparation method of this invention is simple, energy-saving, low-cost, highly operable, and suitable for large-scale production. The modified silicon suboxide material prepared by this method, as an anode material, has the characteristics of high tap density, high initial efficiency, high capacity, and good cycle performance. Attached Figure Description

[0026] Figure 1 This is an HRTEM image of the modified silicon suboxide material prepared in Example 6;

[0027] Figure 2 These are XRD patterns of modified silica materials prepared in some of the embodiments and comparative examples;

[0028] Figure 3 These are the first-cycle charge-discharge curves of the modified silicon suboxide material prepared in Example 6 and the silicon suboxide material in Comparative Example 1.

[0029] Figure 4These are the cycling curves of the modified silicon suboxide material prepared in Example 6 and the silicon suboxide material in Comparative Example 1.

[0030] Figure 5 These are the rate scaling curves of the modified silicon suboxide material prepared in Example 6 and the silicon suboxide material in Comparative Example 1.

[0031] Figure 6 These are the cycle curves of the modified silica-suboxide material and graphite material prepared in Examples 5-7. Detailed Implementation

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] The first aspect of this invention provides a method for preparing a modified silicon suboxide material, the method comprising the following steps:

[0034] (1) Silicate and lithium stearate were ball-milled to obtain a mixed precursor;

[0035] (2) The mixed precursor obtained in step (1) is sintered in an inert atmosphere to obtain modified silicon suboxide material.

[0036] The sintering temperature is 200-900℃.

[0037] According to the present invention, in step (1), the weight ratio of silicon suboxide to lithium stearate can be 1-9:1, preferably 1-3:1. Specifically, the weight ratio of silicon suboxide to lithium stearate can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1 or 9:1, etc.

[0038] According to the present invention, in step (1), the silicon suboxide is preferably silicon suboxide powder. By ball milling the silicon suboxide in powder form, the ball milling mixture can be more uniform, and the ball milling process can moderately break it up. The exposed fresh surface is conducive to the formation of silicates during the thermal induction process. Preferably, the particle size D50 of the silicon suboxide is 1-10 μm, more preferably 3-5 μm.

[0039] According to the present invention, the lithium stearate is not particularly limited, and lithium stearate powder or crystals can be used, preferably lithium stearate powder.

[0040] Both silicon suboxide and lithium stearate used in this invention are commercially available and can be ground as needed to obtain a suitable particle size.

[0041] To ensure thorough mixing of silica suboxide and lithium stearate, the ball milling conditions preferably include: a ball-to-material ratio of 5-15:1, a rotation speed of 400 rpm or higher, and a milling time of 2-8 hours; more preferably, a ball-to-material ratio of 8-13:1, a rotation speed of 400-800 rpm, more preferably 400-600 rpm, and a milling time of 4-8 hours. By ball milling under these conditions, silica suboxide and lithium stearate can be further broken down during mixing, thereby preparing a modified silica suboxide material with better electrochemical performance.

[0042] In this invention, step (2) involves sintering the mixed precursor obtained in step (1) to obtain a modified silicon suboxide material. According to this invention, in step (2), the sintering process causes at least a portion of the SiO on the surface of the silicon suboxide to undergo lithiation, forming lithium silicate and amorphous carbon. Simultaneously, some SiO disproportionates to form Si and SiO2, thereby forming a modified silicon suboxide material with a core-shell structure. In this invention, lithium silicate refers to the general term for various silicates formed by the lithiation of SiO, such as Li2Si2O5, Li2Si2O3, etc., preferably Li2Si2O5.

[0043] The sintering temperature can be 200-900℃, preferably 300-800℃. Furthermore, the sintering time is preferably 2-8 hours, more preferably 3-5 hours.

[0044] According to a preferred embodiment of the present invention, the sintering treatment may include medium-temperature melting and high-temperature calcination. For example, the medium-temperature melting temperature may be 200-400℃, preferably 250-350℃, and the melting time may be 2-4 hours, preferably 2.5-3.5 hours. The high-temperature calcination temperature may be 700-900℃, preferably 750-850℃, and the calcination time may be 2-4 hours, preferably 2-3 hours. By employing a sintering treatment method combining medium-temperature melting and high-temperature calcination, the electrochemical performance of the modified silicon suboxide material can be further improved.

[0045] In addition, the inert atmosphere used in the sintering process is not particularly limited. For example, it can be any one of nitrogen, argon, or a mixture of argon and nitrogen. Preferably, it can be a nitrogen atmosphere or an argon atmosphere.

[0046] According to a preferred embodiment of the present invention, in order to prepare a modified silicon suboxide material with the desired particle size, the method may further include: grinding and / or sieving the sintered product. Grinding and sieving can be performed in a conventional manner, as long as the desired particle size can be obtained. For example, when the modified silicon suboxide material is used as a negative electrode material, it can be ground and sieved using a 300-600 mesh, preferably 300-500 mesh, more preferably 400-500 mesh sieve.

[0047] A second aspect of the present invention provides a modified silicon suboxide material obtained by the preparation method of the present invention described above.

[0048] According to the present invention, the modified silicon suboxide material has a core-shell structure. The core layer is composed of silicon suboxide, silicon dioxide, and silicon, and the shell layer includes lithium silicate (e.g., Li₂Si₂O₅) and amorphous carbon. Specifically, lithium silicate or amorphous carbon is formed at least on a portion of the surface of the modified silicon suboxide material. Lithium silicate is a lithium-ionized product of lithium stearate thermally induced silicon suboxide at high temperatures. In the core-shell structured modified silicon suboxide material of the present invention, the presence of lithium silicate and elemental carbon is not particularly limited. For example, lithium silicate and amorphous carbon can be respectively coated on the surface of silicon suboxide, lithium silicate can be embedded in the surface layer of silicon suboxide and amorphous carbon can be coated on the outer layer of SiO, or lithium silicate can be embedded in an amorphous carbon layer and coated on the surface of silicon suboxide. The content of lithium silicate relative to the total weight of the modified silicon suboxide material can be 0.1-15% by weight, preferably 5-10% by weight. Furthermore, the thickness of the shell layer can be 1-100 nm, preferably 20-60 nm.

[0049] The modified silicon suboxide material according to the present invention, in order to meet the requirements of being used as a negative electrode material in lithium-ion batteries, preferably has a particle size of 2-5 μm, more preferably 3.5-4.5 μm. The particle size of the modified silicon suboxide material can be controlled by appropriate grinding and / or sieving.

[0050] The third aspect of this invention provides the application of the modified silicon suboxide material of the present invention as a negative electrode material in lithium-ion batteries.

[0051] When the modified silicon suboxide material of the present invention is used as the negative electrode material in a lithium-ion battery, the modified silicon suboxide material can be combined with conductive agents, binders, etc., to form a negative electrode film. Furthermore, the modified silicon suboxide material can also be compounded with graphite materials as a negative electrode active material. There are no particular limitations on the conductive agents and binders used; commonly used conductive agents and binders in negative electrode materials can be used. Examples of conductive agents include carbon black, graphite, and SuperP conductive agents; examples of binders include styrene-butadiene rubber and / or carboxymethyl cellulose, preferably a mixture of styrene-butadiene rubber and carboxymethyl cellulose in a weight ratio of 1:0.5-1.5. Additionally, the weight ratio of the modified silicon suboxide material to the conductive agent and binder can be, for example, 5-10:0.5-2:0.5-2, such as 7-9:0.8-1.5:0.8-1.5.

[0052] When used as a negative electrode material in lithium-ion batteries, the modified silicon suboxide material can be mixed with conductive agents, binders, etc., in the above proportions to form a slurry, which is then coated onto a current collector to obtain a negative electrode film. The current collector can be, for example, copper foil.

[0053] By using the modified silicon suboxide material of this invention as the anode material for lithium-ion batteries, the first-cycle discharge specific capacity, first-cycle charge specific capacity, first-charge efficiency, and capacity retention of lithium-ion batteries can be improved, thus comprehensively enhancing the electrochemical performance of lithium-ion batteries. The modified silicon suboxide material of this invention is suitable as a silicon-based anode material for high-energy-density lithium-ion batteries.

[0054] The present invention will be described in detail below through examples. In the following examples and comparative examples, the silicon suboxide powder was purchased from Sichuan Kaiyuan Huineng New Material Technology Co., Ltd., with a particle size D50 of 5 μm; the lithium stearate powder was purchased from Shanghai Bide Pharmaceutical Technology Co., Ltd.; and the graphite material G05 was purchased from Shanghai Yuling New Energy Technology Co., Ltd.

[0055] Example 1

[0056] Silica powder and lithium stearate powder were weighed at a weight ratio of 3:1 and transferred to a planetary ball mill jar. Pure argon gas was introduced into the jar for protection. The mixture was ball-milled for 6 hours at a ball-to-powder ratio of 10:1 and a rotation speed of 450 rpm to obtain the mixed precursor.

[0057] The mixed precursor was placed in a tube furnace and heated to 800°C at a rate of 5°C / min under an Ar atmosphere. It was then calcined for 3 hours. The calcined material was thoroughly ground, crushed, and sieved (400 mesh) to obtain the modified silicon suboxide anode material.

[0058] Example 2

[0059] Silica powder and lithium stearate powder were weighed at a weight ratio of 3:1 and transferred to a planetary ball mill jar. Pure argon gas was introduced into the jar for protection. The mixture was ball-milled for 6 hours at a ball-to-powder ratio of 10:1 and a rotation speed of 450 rpm to obtain the mixed precursor.

[0060] The mixed precursor was placed in a tube furnace and heated to 300°C at a rate of 5°C / min under an Ar atmosphere, held for 3 hours, and then heated to 800°C at a rate of 5°C / min for 2 hours. The calcined material was then thoroughly ground, crushed, and sieved (400 mesh) to obtain the modified silicon suboxide anode material.

[0061] Example 3

[0062] Silica powder and lithium stearate powder were weighed at a weight ratio of 3:1 and transferred to a planetary ball mill jar. Pure argon gas was introduced into the jar for protection. The mixture was ball-milled for 6 hours at a ball-to-powder ratio of 10:1 and a rotation speed of 450 rpm to obtain the mixed precursor.

[0063] The mixed precursors were placed in a tube furnace and heated to 300°C at a rate of 5°C / min under N2 atmosphere, held for 3 hours, and then heated to 700°C at a rate of 5°C / min for 2 hours. After being removed, the precursors were thoroughly ground and crushed and sieved (400 mesh) to obtain modified silicon suboxide anode material.

[0064] Example 4

[0065] Silica powder and lithium stearate powder were weighed at a weight ratio of 3:1 and transferred to a planetary ball mill jar. Pure argon gas was introduced into the jar for protection. The mixture was ball-milled for 6 hours at a ball-to-powder ratio of 10:1 and a rotation speed of 450 rpm to obtain the mixed precursor.

[0066] The mixed precursor was placed in a tube furnace and heated to 300°C at a rate of 5°C / min under an Ar atmosphere, held for 3 hours, and then heated to 900°C at a rate of 5°C / min for 2 hours. After being removed, it was thoroughly ground and crushed and sieved (400 mesh) to obtain the modified silicon suboxide anode material.

[0067] Example 5

[0068] The modified silicon suboxide anode material was prepared according to the method in Example 2, except that the weight ratio of silicon suboxide to lithium stearate was 1:1.

[0069] Example 6

[0070] The modified silicon suboxide anode material was prepared according to the method of Example 2, except that the weight ratio of silicon suboxide to lithium stearate was 1.5:1.

[0071] Example 7

[0072] The modified silicon suboxide anode material was prepared according to the method in Example 2, except that the weight ratio of silicon suboxide to lithium stearate was 2:1.

[0073] Example 8

[0074] The modified silicon suboxide anode material was prepared according to the method of Example 2, except that the weight ratio of silicon suboxide to lithium stearate was 6:1.

[0075] Example 9

[0076] The modified silicon suboxide anode material was prepared according to the method of Example 2, except that the weight ratio of silicon suboxide to lithium stearate was 8:1.

[0077] Comparative Example 1

[0078] Untreated silica powder.

[0079] Comparative Example 2

[0080] The silicon suboxide powder was placed in a tube furnace and heated to 300°C at a rate of 5°C / min under a N2 atmosphere. The temperature was held for 3 hours, and then heated to 800°C at a rate of 5°C / min for 2 hours. After being removed, it was thoroughly ground and crushed to obtain the negative electrode material.

[0081] Comparative Example 3

[0082] The negative electrode material was prepared according to the method of Example 6, except that the lithium stearate powder was replaced with an equal amount of stearic acid.

[0083] Comparative Example 4

[0084] The negative electrode material was prepared according to the method of Example 6, except that the lithium stearate powder was replaced with an equal amount of lithium carbonate.

[0085] Comparative Example 5

[0086] The negative electrode material was prepared according to the method of Example 6, except that the lithium stearate powder was replaced with an equal amount of lithium acetate.

[0087] Test Example 1

[0088] The modified silicon suboxide material prepared in Example 6 was observed using HRTEM (JEOL JEM-2100F high-resolution transmission electron microscope), and the results are as follows. Figure 1 As shown.

[0089] pass Figure 1 The results show that the material prepared using Example 6 of the present invention has a distinct shell and crystal structure.

[0090] Test Example 2

[0091] XRD tests were performed on the negative electrode materials obtained in Examples 2, 5-9 and Comparative Examples 1-3 (Bruker X-ray powder diffractometer: AXS D2 PHASER, test conditions: 5-90°, scan rate: 10° / min). The obtained spectra are shown below. Figure 2 As shown.

[0092] pass Figure 2 The results show that the embodiments obtained by using the present invention all have obvious disproportionation structures, while comparative examples 1-3 do not have obvious disproportionation structures, and the material of example 6 has diffraction peaks of SiO2 and Li2Si2O5, which are consistent with the HRTEM obtained by test example 1.

[0093] Test Example 3

[0094] The tap density of the materials prepared in Examples 5-7 and Comparative Examples 1 and 3-5 was measured using a tap density meter (Ruike Instruments FZS4-4), and the results are shown in Table 1.

[0095] Table 1

[0096] serial number Tap density (g / cm 3 ) Example 5 1.02 Example 6 0.95 Example 7 0.88 Comparative Example 1 0.62 Comparative Example 3 0.85 Comparative Example 4 0.91 Comparative Example 5 0.69

[0097] Table 1 shows that the tap density of the anode material modified with lithium stearate is significantly optimized compared with that of commercial SiO, and the tap density increases with the increase of lithium stearate content.

[0098] A comparison of the results of Example 6 and Comparative Examples 3-5 shows that by using the lithium stearate of the present invention, the tap density of the anode material can be further improved compared to other materials.

[0099] Test Example 4

[0100] The modified silica materials prepared in the above examples and comparative examples were mixed with Super P and binder (a mixture of styrene-butadiene rubber and carboxymethyl cellulose in a weight ratio of 1:1) in a weight ratio of 7:1.5:1.5 to form a slurry. The slurry was uniformly coated onto a copper foil current collector to obtain a negative electrode film. A button cell was assembled in an argon glove box using a lithium metal sheet as the positive electrode.

[0101] The battery was tested using the following method, and the results are shown in Table 2. Figure 3 The first-cycle charge-discharge curves of the modified silicon suboxide material prepared in Example 6 and the silicon suboxide material in Comparative Example 1 are shown. Figure 4 Cyclic curves of the modified silicon suboxide material prepared in Example 6 and the silicon suboxide material in Comparative Example 1 are shown. Figure 5 The rate curves of the modified silicon suboxide material prepared in Example 6 and the silicon suboxide material in Comparative Example 1 are shown.

[0102] Charge and discharge test: The first test program is 0.1C, 0.05C, 0.01C multiple discharges and 0.1C charging. After the second test, the program is 0.2C, 0.1C, 0.05C, 0.01C multiple discharges and 0.2C charging. The charge and discharge range is 0.01-2.0V.

[0103] Rate performance test: Charge and discharge at 0.1C, 0.2C, 0.5C, 1C, and 0.2C respectively, with constant voltage charging step added.

[0104] Table 2

[0105]

[0106] In the table above, ICE represents the first Coulomb efficiency, also referred to as first efficiency below.

[0107] Through Table 2 and Figure 3-5 The results show that the modified silicon suboxide material synthesized using the method of the present invention has good first-efficiency and cycling performance, with Example 6 showing a significantly better first-efficiency effect.

[0108] The comparison between Example 2 and Comparative Examples 3-5 shows that, by using lithium stearate, compared with stearic acid, lithium carbonate and lithium acetate, the modified silicon suboxide material obtained has obvious advantages in capacity and first-efficiency performance under the same mass ratio and the same synthesis method and conditions.

[0109] The comparison results of Examples 2 and 5-9 show that the modified silicon suboxide material of Examples 5-7 has a higher initial coulombic efficiency and relatively better cycle performance. Therefore, the preferred weight ratio of silicon suboxide to lithium stearate is 1-2:1.

[0110] The comparison of Examples 1-2 shows that by adding a heat preservation process at 250-350°C, that is, by making the sintering process include medium-temperature melting and high-temperature calcination, the electrochemical performance of the modified silicon suboxide material is better.

[0111] The comparison of Examples 2-4 shows that the modified silicon suboxide material obtained by high-temperature calcination at 750-850℃ has better electrochemical performance.

[0112] Test Example 2

[0113] The modified silica material obtained in Examples 5-7 was compounded with graphite material G05 according to the compounding amounts in Table 2. The resulting composite material was mixed with Super P and binder (a mixture of styrene-butadiene rubber and carboxymethyl cellulose in a weight ratio of 1:1) in a weight ratio of 8:1:1 to form a slurry. The slurry was uniformly coated onto a copper foil current collector to obtain a negative electrode film. A button cell was assembled in an argon glove box using a lithium metal sheet as the positive electrode.

[0114] The battery was tested using the following method, and the results are shown in Table 2. Figure 6 The cycling curves of the modified silica-suboxide material and graphite material prepared in Examples 5-7 are shown.

[0115] Charge and discharge test: The first test program is 0.1C, 0.05C, 0.01C multiple discharges and 0.1C charging. After the second test, the program is 0.2C, 0.1C, 0.05C, 0.01C multiple discharges and 0.2C charging. The charge and discharge range is 0.01-2.0V.

[0116] Table 2

[0117]

[0118] In the table above, ICE represents the initial coulomb efficiency.

[0119] Through Table 2 and Figure 6 The results show that the modified silica suboxide material of Examples 5-7 of the present invention, when combined with graphite, has significantly better initial efficiency and cycle performance.

[0120] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a modified silica-substrate material, characterized in that, The method includes the following steps: (1) The silica suboxide and lithium stearate were ball-milled to obtain a mixed precursor; (2) The mixed precursor obtained in step (1) is sintered in an inert atmosphere to obtain modified silicon suboxide material; The sintering process includes medium-temperature melting and high-temperature calcination. The medium-temperature melting temperature is 200-400℃ and the melting time is 2-4 hours. The high-temperature calcination temperature is 700-900℃ and the calcination time is 2-4 hours. The modified silicon suboxide material has a core-shell structure, with the core layer comprising silicon suboxide, silicon dioxide, and silicon, and the shell layer comprising lithium silicate and amorphous carbon.

2. The preparation method according to claim 1, wherein, The weight ratio of silicon suboxide to lithium stearate is 1-9:

1.

3. The preparation method according to claim 1, wherein, The weight ratio of silicon suboxide to lithium stearate is 1-3:

1.

4. The preparation method according to claim 1, wherein, The silicon suboxide is silicon suboxide powder.

5. The preparation method according to claim 4, wherein, The particle size D50 of the silicon suboxide is 1-10 μm.

6. The preparation method according to any one of claims 1-5, wherein, The conditions for ball milling include: a ball-to-material ratio of 5-15:1, a rotation speed of 400 rpm or higher, and a ball milling time of 2-10 hours.

7. The preparation method according to any one of claims 1-5, wherein, The inert atmosphere is any one of nitrogen, argon, or a mixture of argon and nitrogen.

8. The preparation method according to any one of claims 1-5, wherein, The method further includes grinding and / or sieving the sintered product.

9. The preparation method according to claim 8, wherein, The sieve used for screening is 300-600 mesh.

10. The modified silicon suboxide material obtained by the preparation method according to any one of claims 1-9.

11. The modified silicon suboxide material according to claim 10, wherein, The modified silica material has a particle size of 2-5 μm.

12. The application of the modified silicon suboxide material according to claim 10 or 11 as a negative electrode material in lithium-ion batteries.

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