Silicon-oxygen-carbon negative electrode material with high lithium storage performance and preparation method thereof

Abstract

The application provides a high lithium storage performance silicon-oxygen-carbon negative electrode material and a preparation method, the method comprising the following steps: S1, obtaining a polymer precursor through hydrolysis-polycondensation reaction of phenyl triethoxysiloxane; S2, obtaining an unmodified silicon-oxygen-carbon SiOC material through high-temperature pyrolysis of the polymer precursor; and S3, obtaining the high lithium storage performance silicon-oxygen-carbon negative electrode material through carbon coating on the surface of the silicon-oxygen-carbon material. The method of the embodiment of the application is simple in preparation process, and the cycle stability of the negative electrode material prepared by the method is obviously improved, and the negative electrode material exhibits good electrochemical performance as a lithium ion battery negative electrode material.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery material preparation, and particularly to silicon-oxygen-carbon anode materials with high lithium storage performance and their preparation methods. Background Technology

[0002] Silicon-oxygen-carbon (SiOC) has long been a focus of research and attention as a high-capacity anode material for lithium-ion batteries. However, its lithium storage mechanism remains unclear. Currently, the lithium storage performance of SiOC materials is related to numerous factors, including its chemical composition, microstructure, conductivity, particle size, morphology, and microporous structure. SiOC materials consist of a SiOC glass phase and free carbon, and possess abundant microporous structures; their electrochemical performance is related to all three. SiOC materials with different compositions exhibit significantly different electrochemical performances. Therefore, studying the relationship between the composition of SiOC materials and their lithium storage performance is of great significance.

[0003] However, the cycling stability exhibited by electrodes made from existing negative electrode materials during charge-discharge cycles does not meet the requirements for battery performance, thus, there is a need to improve this issue. Summary of the Invention

[0004] In view of this, the present invention provides a silicon-oxygen-carbon anode material with high lithium storage performance and a preparation method thereof. The silicon-oxygen-carbon material prepared by this method is a monodisperse spherical particle with a relatively high content of free carbon inside and significantly improved cycle stability. It exhibits good electrochemical performance as a lithium-ion battery anode material.

[0005] Some embodiments of the present invention provide a method for preparing a silicon-oxygen-carbon anode material with high lithium storage performance. The present invention is described below from multiple aspects, and the embodiments and beneficial effects described below can be referred to mutually.

[0006] In a first aspect, the present invention provides a method for preparing a silicon-oxygen-carbon anode material with high lithium storage performance, comprising:

[0007] S1, the polymer precursor is obtained by hydrolysis-condensation reaction of phenyltriethoxysiloxane;

[0008] S2, the polymer precursor is pyrolyzed at high temperature to obtain unmodified silicon-oxygen-carbon (SiOC) material;

[0009] S3, carbon coating is applied to the surface of the silicon-oxygen-carbon material to obtain the silicon-oxygen-carbon anode material with high lithium storage performance.

[0010] The high-lithium-storage-performance silicon-oxygen-carbon anode material and its preparation method according to embodiments of the present invention can obtain monodisperse spherical silicon-oxygen-carbon materials with a relatively high internal free carbon content. Further surface carbon coating modification yields a composite material. Compared to the unmodified material, the cycle stability is significantly improved, exhibiting excellent electrochemical performance as a lithium-ion battery anode material.

[0011] As one embodiment of the first aspect, step S1 includes:

[0012] S11, add 0.5-2 mL of tetraethyl orthosilicate and the phenyltriethoxysiloxane mixture to a mixed solution containing 0.3-0.7 mL hydrochloric acid solution, 0.8-1.5 mL deionized water and 3-6 mL ethanol, stir, and obtain the hydrolysis product;

[0013] S12, the hydrolysis product is rapidly added to a mixed solution containing 0.3-0.8 mL of ammonia and 10-20 mL of deionized water, and the mixture is stirred and reacted at room temperature. The product is washed with deionized water and ethanol, centrifuged, and dried to obtain the polymer precursor.

[0014] As one embodiment of the first aspect, the volume ratio of the tetraethyl orthosilicate to the phenyltriethoxysiloxane solution is (2-8):(8-2).

[0015] As one embodiment of the first aspect, the volume ratio of the tetraethyl orthosilicate to the phenyltriethoxysiloxane solution is 3:7.

[0016] As an embodiment of the first aspect, step S2 includes: pyrolyzing the polymer precursor in a nitrogen atmosphere to obtain the unmodified silicon-oxygen-carbon (SiOC) material.

[0017] As an embodiment of the first aspect, step S3 includes: uniformly mixing 60-100 mg of the silicon-oxygen-carbon material with 10-30 mg of polyvinylidene fluoride powder, dispersing the mixture in 0.5-2 mL of N-methylpyrrolidone, drying the mixture, and pyrolyzing the dried product in a nitrogen atmosphere to obtain the carbon-coated silicon-oxygen-carbon anode material with high lithium storage performance.

[0018] As one embodiment of the first aspect, the concentration of the hydrochloric acid solution is less than 0.01 mol / L, and the concentration of the ammonia solution is 28 wt%.

[0019] As an embodiment of the first aspect, in S2, the temperature at which the pyrolysis is carried out in a nitrogen atmosphere is between 850°C and 950°C.

[0020] As an embodiment of the first aspect, in S3, the temperature at which the pyrolysis is carried out in a nitrogen atmosphere is between 450°C and 550°C.

[0021] Secondly, the present invention also provides a silicon-oxygen-carbon anode material with high lithium storage performance, which is prepared by the preparation method described in the first aspect embodiment. The silicon-oxygen-carbon anode material has a monodisperse nano / micro spherical particle morphology and its surface is coated with carbon.

[0022] The above-described technical solution of the present invention has at least one of the following beneficial effects:

[0023] According to an embodiment of the present invention, a method for preparing a high-lithium-storage silicon-oxygen-carbon anode material involves mixing tetraethyl orthosilicate into phenyltriethoxysiloxane, using the mixture of the two components as raw materials, and employing a method of hydrolysis-condensation reaction followed by high-temperature pyrolysis to prepare SiOC material. Then, polyvinylidene fluoride is used as a carbon source for carbon coating modification to prepare SiOC@C composite material. Since SiOC material consists of monodisperse spherical particles, its internal free carbon content is relatively high. Further carbon coating and surface modification can yield an even higher carbon content. Compared with existing materials, the SiOC@C composite material of the present invention can effectively improve the cycle stability of the electrode, and this material exhibits excellent electrochemical performance as a lithium-ion battery anode material. Attached Figure Description

[0024] Figure 1 A flowchart illustrating a method for preparing a silicon-oxygen-carbon anode material with high lithium storage performance according to an embodiment of the present invention;

[0025] Figure 2 This is a trend chart showing the constant current charge-discharge cycle performance of the SiOC-0.2T0.8P, SiOC-0.3T0.7P, SiOC-0.4T0.6P, SiOC-0.5T0.5P and SiOC-0.6T0.4P materials of the present invention at a current density of 100 mA / g after the rate performance test (20 cycles);

[0026] Figure 3 The graph shows the rate performance and cycling performance at 100 mA / g current density of SiOC-0.3T0.7P and SiOC-0.3T0.7P@C of the present invention.

[0027] Figure 4 The graph shows the trend of long-cycle performance of the two electrodes, SiOC-0.3T0.7P and SiOC-0.3T0.7P@C, after rate performance testing (20 cycles) at a current density of 100 mA / g, according to one embodiment of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] To facilitate understanding of the present invention, the technical principles discovered will be explained first.

[0030] Silicon-oxygen-carbon (SiO2-C) composites offer significant practical advantages by improving both specific capacity and cycle stability. For instance, the SiOC@G composite exhibits good electrochemical activity and cycle stability. Graphene composites enhance conductivity and stabilize the material's structure, thereby improving its lithium storage performance. Studies have shown that this material exhibits an initial reversible capacity of approximately 600 mAh / g, which remains at 582 mAh / g after 90 cycles. This benefit is attributed to the composite material's ability to mitigate volume changes during lithium insertion / extraction processes.

[0031] Based on these findings, this invention provides a method for preparing a silicon-oxygen-carbon anode material with high lithium storage performance to improve the conductivity and cycle stability of SiOC materials. The SiOC material is obtained by first hydrolyzing and polycondensing phenyltriethoxysiloxane, followed by high-temperature pyrolysis. Furthermore, to further improve the cycle stability of the SiOC material, polyvinylidene fluoride (PVDF) is used as a carbon source and carbon-coated to prepare a silicon-oxygen-carbon (SiOC@C) composite material with high lithium storage performance. This material exhibits significantly improved cycle stability and superior high lithium storage performance.

[0032] The preparation method of the silicon-oxygen-carbon anode material with high lithium storage performance according to the present invention will be described below with reference to the accompanying drawings.

[0033] It should be noted that the sources of raw materials not mentioned in this invention may be commercially available or prepared by conventional methods, and this invention does not limit them.

[0034] refer to Figure 1 , Figure 1 A flowchart illustrating a method for preparing a silicon-oxygen-carbon anode material with high lithium storage performance according to an embodiment of the present invention is shown. Figure 1 As shown, the method includes S1-S3, and each step is described below.

[0035] In S1, the polymer precursor is obtained by hydrolysis-condensation reaction of phenyltriethoxysiloxane.

[0036] The first concentration of HCl solution is low to ensure that PhTES is kept in a weakly acidic environment during hydrolysis. For example, it can be less than 0.1 mol / L, such as 0.01 mol / L, 0.05 mol / L, and 0.1 mol / L.

[0037] In one embodiment of the present invention, the preparation process of phenyltriethoxysiloxane is as follows: S11, 0.5-2 mL of tetraethyl orthosilicate and the phenyltriethoxysiloxane mixture are added to a mixed solution containing 0.3-0.7 mL of hydrochloric acid solution, 0.8-1.5 mL of deionized water and 3-6 mL of ethanol, and stirred to obtain the hydrolysis product. The hydrochloric acid solution can be 0.4 mL, 0.5 mL, or 0.6 mL, etc. The deionized water can be 0.9 mL, 1.0 mL, 1.1 mL, 1.2 mL, 1.3 mL, or 1.4 mL, etc. The ethanol can be 4 mL or 5 mL. The tetraethyl orthosilicate can be 0.8 mL, 1.1 mL, 1.2 mL, 1.4 mL, 1.6 mL, 1.7 mL, or 1.8 mL, etc.

[0038] In some embodiments, S11 may include: adding 1 mL of a mixture of tetraethyl orthosilicate (TEOS) and phenyltriethoxy-silane (PhTES) to a mixed solution containing 0.3-0.8 mL of HCl solution, 1.1 mL of deionized water and 4 mL of ethanol under magnetic stirring, and stirring mechanically or magnetically at room temperature to obtain a hydrolysis product of PhTES, such as an ethoxylated organosilicon oligomer.

[0039] The hydrolysis time can be 5-9 hours, with 7 hours being the preferred time.

[0040] In an embodiment of the present invention, the volume ratio of TEOS to PhTES in the mixture is 3:7. In other embodiments of the present invention, it can also be 2:8, 6:4, 5:5, 4:6, 7:3, or 8:2.

[0041] S12, the hydrolysis product is rapidly added to a mixed solution containing 0.3-0.8 mL of ammonia water (e.g., 0.4 mL, 0.5 mL, 0.6 mL, or 0.7 mL) and 10-20 mL of deionized water (the deionized water can be 13 mL, 15 mL, or 18 mL, etc.). The mixture is stirred and reacted at room temperature. The product is then washed with deionized water and ethanol, centrifuged, and dried to obtain the polymer precursor.

[0042] Furthermore, the hydrolysis product (sol) can be rapidly added to a mixed solution containing 0.5 mL ammonia and 14 mL deionized water, and the mixture can be stirred and reacted at room temperature. The product is then washed with deionized water and ethanol, centrifuged, and dried to obtain the polymer precursor.

[0043] In this invention, the concentration of ammonia water can be the concentration of ordinary reagent-grade ammonia water, for example, about 28 wt%.

[0044] The reaction time of the hydrolysis product in ammonia water can be 40-60 hours, preferably 48 hours. To ensure that the hydrolysis product reacts fully with the ammonia water, the mixture is stirred continuously when the hydrolysis product is added.

[0045] In S2, the polymer precursor is pyrolyzed at high temperature to obtain unmodified silicon-oxygen-carbon (SiOC) material.

[0046] Unmodified (pristine) SiOC material can be obtained by pyrolyzing the polymer precursor in a nitrogen atmosphere. A nitrogen atmosphere allows for better pyrolysis of the polymer precursor into silicon-oxygen-carbon, preventing product oxidation and reducing yield. The temperature range in the nitrogen atmosphere can be controlled between 850℃ and 950℃, preferably with a pyrolysis temperature of 900℃ and a heating rate of approximately 5℃ / min. The pyrolysis time can be 2 hours.

[0047] In S3, the surface of the silicon-oxygen-carbon material is coated with carbon to obtain a silicon-oxygen-carbon anode material with high lithium storage performance.

[0048] Specifically, 60-100 mg of SiOC material can be uniformly mixed with 10-30 mg of polyvinylidene fluoride (PVDF) powder and then dispersed in 1-2 mL of N-methylpyrrolidone (NMP). The mixture is then dried in a vacuum oven at approximately 120°C for about 12 hours. The polymer precursor is then pyrolyzed in a nitrogen atmosphere to obtain carbon-coated SiOC@C composite material (a silicon-oxygen-carbon anode material with high lithium storage performance). The SiOC material can be 70 mg, 80 mg, or 90 mg, etc. The polyvinylidene fluoride can be 12 mg, 14 mg, 16 mg, or 18 mg, etc. The 1-2 mL of N-methylpyrrolidone can be 1.2 mL, 1.5 mL, or 1.8 mL, etc.

[0049] In embodiments of the present invention, the pyrolysis temperature in a nitrogen atmosphere can be 450°C to 550°C, preferably 500°C. A nitrogen atmosphere allows for better pyrolysis of the polymer precursor into silicon-oxygen-carbon, preventing product oxidation and reducing yield. Furthermore, the heating rate of 5°C / min used in this invention is more conducive to the efficient pyrolysis of the polymer precursor into silicon-oxygen-carbon and facilitates carbon coating on the surface of silicon-oxygen-carbon, significantly improving the cycling stability of the SiOC material.

[0050] The method for preparing a high-lithium-storage silicon-oxygen-carbon anode material according to embodiments of the present invention is simple. Using PhTES and TEOS in a specific ratio as raw materials, a precursor is prepared via a PhTES hydrolysis-condensation reaction, followed by high-temperature pyrolysis to produce SiOC material. A SiOC@C composite material is then obtained by carbon coating the surface. This material exhibits good cycle stability. During rate testing, at a current density of 100 mA / g, its initial reversible capacity is 542.8 mAh / g, and after 100 cycles, its capacity remains at 523.9 mAh / g, with a capacity retention of 93.1%, significantly higher than that of the untreated SiOC material.

[0051] Furthermore, this invention also discloses a silicon-oxygen-carbon anode material with high lithium storage performance, which is composed of... Figure 1 The described preparation method yields a silicon-oxygen-carbon anode material with high lithium storage performance. This material exhibits a monodisperse nano / micro spherical particle morphology with a relatively high internal free carbon content and a carbon-coated surface. Compared to unmodified silicon-oxygen-carbon materials, while the initial reversible charge specific capacity of this material is slightly lower, its cycle stability is significantly improved, demonstrating excellent electrochemical performance as a lithium-ion battery anode material.

[0052] The preparation method of the high lithium storage performance silicon-oxygen-carbon anode material of the present invention will be further described below with reference to specific embodiments.

[0053] Example 1

[0054] (1) Under magnetic stirring, add 0.3 mL of TEOS (tetraethyl orthosilicate) and 0.7 mL of PhTES (phenyltriethoxysiloxane) mixed solution to a mixed solution containing 0.5 mL of 0.01 mol / L HCl solution, 1.1 mL of deionized water and 4 mL of ethanol, and stir at room temperature for 7 h to obtain hydrolysis product.

[0055] (2) Under magnetic stirring, the hydrolysis product (sol) was quickly added to a mixed solution containing 0.5 mL of 28 wt% ammonia and 14 mL of deionized water. Stirring was continued for 48 h at room temperature. The product was washed with deionized water and ethanol, centrifuged, and dried.

[0056] (3) The dried product (polymer precursor) was heated to 900°C in a nitrogen atmosphere at a heating rate of 5°C / min, and pyrolyzed at 900°C for 2 hours. After cooling to room temperature, the unmodified SiOC material was obtained, which was denoted as SiOC-0.3T0.7P material.

[0057] (4) 80 mg of SiOC-0.3T0.7P material was uniformly mixed with 20 mg of PVDF (polyvinylidene fluoride) powder and dispersed in 1.2 mL of NMP (N-methylpyrrolidone). The mixture was then dried in a vacuum oven at 120 °C for 12 h. The dried product (polymer precursor) was then heated to 500 °C in a nitrogen atmosphere at a heating rate of 5 °C / min and pyrolyzed at 500 °C for 2 h. After cooling to room temperature, a carbon-coated carbon-oxygen-silicon composite material was obtained, denoted as SiOC-0.3T0.7P@C material.

[0058] Comparative Example 1

[0059] (1) Under magnetic stirring, 0.2 mL of TEOS (tetraethyl orthosilicate) and 0.8 mL of PhTES (phenyltriethoxysiloxane) were added to a mixed solution containing 0.5 mL of 0.01 mol / L HCl solution, 1.1 mL of deionized water and 4 mL of ethanol, and stirred at room temperature for 7 h to obtain the hydrolysis product.

[0060] (2) Under magnetic stirring, the hydrolysis product (sol) was rapidly added to a mixed solution containing 0.5 mL ammonia (28 wt%) and 14 mL deionized water. The mixture was stirred for 48 h at room temperature. The product was washed with deionized water and ethanol, centrifuged, and dried. Finally, the dried product (polymer precursor) was heated to 900 °C in a nitrogen atmosphere (heating rate of 5 °C / min) and pyrolyzed at 900 °C for 2 h. After cooling to room temperature, unmodified SiOC (Pristine SiOC) material was obtained, denoted as SiOC-0.2T0.8P material.

[0061] Comparative Example 2

[0062] (1) Under magnetic stirring, 0.4 mL of TEOS (tetraethyl orthosilicate) and 0.6 mL of PhTES (phenyltriethoxysiloxane) were added to a mixed solution containing 0.5 mL of 0.01 mol / L HCl solution, 1.1 mL of deionized water and 4 mL of ethanol, and stirred at room temperature for 7 h to obtain the hydrolysis product.

[0063] (2) Under magnetic stirring, the hydrolysis product (sol) was rapidly added to a mixed solution containing 0.5 mL ammonia (28 wt%) and 14 mL deionized water. The mixture was stirred for 48 h at room temperature. The product was washed with deionized water and ethanol, centrifuged, and dried. Finally, the dried product (polymer precursor) was heated to 900 °C in a nitrogen atmosphere (heating rate of 5 °C / min) and pyrolyzed at 900 °C for 2 h. After cooling to room temperature, the unmodified SiOC material was obtained, denoted as SiOC-0.4T0.6P material.

[0064] Comparative Example 3

[0065] (1) Under magnetic stirring, add 0.5 mL of TEOS (tetraethyl orthosilicate) and 0.5 mL of PhTES (phenyltriethoxysiloxane) to a mixed solution containing 0.5 mL of 0.01 mol / L HCl solution, 1.1 mL of deionized water and 4 mL of ethanol, and stir at room temperature for 7 h to obtain the hydrolysis product.

[0066] (2) Under magnetic stirring, the hydrolysis product (sol) was rapidly added to a mixed solution containing 0.5 mL ammonia (28 wt%) and 14 mL deionized water. The mixture was stirred for 48 h at room temperature. The product was washed with deionized water and ethanol, centrifuged, and dried. Finally, the dried product (polymer precursor) was heated to 900 °C in a nitrogen atmosphere (heating rate of 5 °C / min) and pyrolyzed at 900 °C for 2 h. After cooling to room temperature, the unmodified SiOC material was obtained, denoted as SiOC-0.5T0.5P material.

[0067] Comparative Example 4

[0068] (1) Under magnetic stirring, add 0.6 mL of TEOS (tetraethyl orthosilicate) and 0.4 mL of PhTES (phenyltriethoxysiloxane) mixed solution to a mixed solution containing 0.5 mL of 0.01 mol / L HCl solution, 1.1 mL of deionized water and 4 mL of ethanol, and stir at room temperature for 7 h to obtain hydrolysis product.

[0069] (2) Under magnetic stirring, the hydrolysis product (sol) was rapidly added to a mixed solution containing 0.5 mL ammonia (28 wt%) and 14 mL deionized water. The mixture was stirred for 48 h at room temperature. The product was washed with deionized water and ethanol, centrifuged, and dried. Finally, the dried product (polymer precursor) was heated to 900 °C in a nitrogen atmosphere (heating rate of 5 °C / min) and pyrolyzed at 900 °C for 2 h. After cooling to room temperature, the unmodified SiOC material was obtained, denoted as SiOC-0.6T0.4P material.

[0070] The performance of the materials prepared in the above embodiments was verified through experiments.

[0071] refer to Figure 2 , Figure 2 The graph shows the trend of the constant current charge-discharge cycle performance of five materials of the present invention—SiOC-0.2T0.8P, SiOC-0.3T0.7P, SiOC-0.4T0.6P, SiOC-0.5T0.5P, and SiOC-0.6T0.4P—at a current density of 100 mA / g after rate performance testing (20 cycles). Figure 2 As can be seen, the initial reversible charge specific capacities of the five materials are as follows: SiOC-0.2T0.8P is 456.6 mAh / g, SiOC-0.3T0.7P is 666.6 mAh / g, SiOC-0.4T0.6P is 635.8 mAh / g, SiOC-0.5T0.5P is 472.7 mAh / g, and SiOC-0.6T0.4P is 376.9 mAh / g. After 100 cycles, the reversible charge specific capacities are 242.3 mAh / g, 418.2 mAh / g, 222.3 mAh / g, 331.9 mAh / g, and 279.8 mAh / g, respectively. The capacity retention rates are 53.1%, 62.7%, 35%, 70.2%, and 74.2%, respectively. Among them, considering only the two materials with relatively high initial specific capacity, SiOC-0.3T0.7P and SiOC-0.4T0.6P, SiOC-0.3T0.7P not only has a relatively high initial specific capacity (666.6 mAh / g), but also has good cycling stability (capacity retention can reach 62.7%).

[0072] Figure 3 The graphs showing the rate performance and cycling performance at 100 mA / g of SiOC-0.3T0.7P and SiOC-0.3T0.7P@C according to the present invention are illustrated. Figure 3As shown, the specific recharge capacities of SiOC-0.3T0.7P material at current densities of 100mA / g, 200mA / g, 500mA / g, and 1000mA / g are 812.2 mAh / g, 651 mAh / g, 490.7 mAh / g, and 395.8 mAh / g, respectively. The specific recharge capacities of SiOC-0.3T0.7P@C material at current densities of 100mA / g, 200mA / g, 500mA / g, and 1000mA / g are 761.7 mAh / g, 557.7 mAh / g, 443.2 mAh / g, and 366.7 mAh / g, respectively. When the current density increased from 100 mA / g to 1000 mA / g, the capacity retention rates of the two electrodes were 48.7% and 48.1%, respectively, which were basically equivalent, indicating that both SiOC-0.3T0.7P and SiOC-0.3T0.7P@C have good cycle stability.

[0073] Figure 4 The graph shows the long-cycle performance trends of the two electrodes, SiOC-0.3T0.7P and SiOC-0.3T0.7P@C, after a rate performance test (20 cycles) at a current density of 100 mA / g. The initial reversible charge specific capacities of the two electrodes were 666.6 mAh / g and 557.1 mAh / g, respectively. After 100 cycles, their reversible charge specific capacities were 418.2 and 518.6 mAh / g, respectively, with capacity retention rates of 62.7% and 93.1%, respectively. This demonstrates that although the carbon-coated modified SiOC-0.3T0.7P@C material has a slightly lower initial specific capacity, after 100 cycles, its capacity retention rate is as high as 93.1%, far exceeding the 62.7% of the uncoated modified SiOC-0.3T0.7PC material, exhibiting better cycle stability.

[0074] It should be noted that in the examples and description of this patent, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0075] Although the invention has been illustrated and described with reference to certain preferred embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

1. A method for preparing a silicon-oxygen-carbon negative electrode material with high lithium storage performance, characterized in that, include: S1, a polymer precursor is obtained by hydrolyzing and polycondensing a mixture of tetraethyl orthosilicate and phenyltriethoxysiloxane; S2, the polymer precursor is pyrolyzed at high temperature to obtain unmodified silicon-oxygen-carbon (SiOC) material; S3, the surface of the silicon-oxygen-carbon material is coated with carbon to obtain the silicon-oxygen-carbon anode material with high lithium storage performance. The silicon-oxygen-carbon anode material has a monodisperse nano / micro spherical particle morphology and its surface is coated with carbon. S1 includes: S11, add 0.5-2 mL of tetraethyl orthosilicate and the phenyltriethoxysiloxane mixture to a mixed solution containing 0.3-0.7 mL hydrochloric acid solution, 0.8-1.5 mL deionized water and 3-6 mL ethanol, stir, and obtain the hydrolysis product, wherein the concentration of the hydrochloric acid solution is less than 0.01 mol / L; S12, the hydrolysis product is rapidly added to a mixed solution containing 0.3-0.8 mL of ammonia and 10-20 mL of deionized water, and the mixture is stirred and reacted at room temperature. The product is washed with deionized water and ethanol, centrifuged, and dried to obtain the polymer precursor. The concentration of the ammonia is 28 wt%. The volume ratio of the tetraethyl orthosilicate to the phenyltriethoxysiloxane solution is (2-8):(8-2).

2. The production method according to claim 1, characterized by, The volume ratio of the tetraethyl orthosilicate to the phenyltriethoxysiloxane solution is 3:

7.

3. The preparation method according to claim 1, characterized in that, S2 includes: The polymer precursor was pyrolyzed in a nitrogen atmosphere to obtain the unmodified silicon-oxygen-carbon (SiOC) material.

4. The method of claim 1, wherein, S3 includes: The silicon-oxygen-carbon material is uniformly mixed with 10-30 mg of polyvinylidene fluoride powder, dispersed in 1-2 mL of N-methylpyrrolidone, dried, and the dried product is pyrolyzed in a nitrogen atmosphere to obtain the silicon-oxygen-carbon anode material with high lithium storage performance coated with carbon.

5. The preparation method according to claim 3, characterized in that, In S2, the temperature at which the pyrolysis is performed in a nitrogen atmosphere is between 850°C and 950°C.

6. The preparation method according to claim 4, characterized in that, In S3, the temperature at which the pyrolysis is performed in a nitrogen atmosphere is between 450°C and 550°C.

7. A silicon-oxygen-carbon negative electrode material with high lithium storage performance, characterized in that, Prepared by the preparation method of any one of claims 1 to 6, the silicon-oxygen-carbon anode material is a monodisperse nano / micro spherical particle morphology with its surface coated with carbon.

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