Preparation method and application of lithium battery negative electrode material and lithium ion battery

Abstract

The invention provides a preparation method and application of a lithium battery negative electrode material and a lithium ion battery. According to the preparation method, MMT is taken as a template, VTES (vinyltriethoxysilane) is taken as a silicon source, resorcinol is taken as a carbon source, and the MMT-coated SiOx / C composite material is prepared by oxidative polymerization and high-temperature calcination through a sol-gel method. The introduction of MMT enhances the interface bonding force with the carbon layer, the natural layered structure can relieve the volume expansion stress of the electrode material, the high specific surface area can adsorb lithium ions and improve the conductivity, and the electrochemical performance of the SiOx / C material is effectively improved. Under 2.0 A / g, after 500 cycles, the capacity retention ratio of MMT coated SiOx / C reaches up to 92.36%, which is far higher than the capacity retention ratio (73.51%) of SiOx / C.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly to a preparation method and application of a lithium-ion battery anode material, and a lithium-ion battery. Background Art

[0002] With the transformation of the global energy structure towards cleaner and lower-carbon forms, lithium-ion batteries, as the core components of electric vehicles and renewable energy storage systems, have an increasingly urgent demand for electrode materials with high energy density and long cycle life. Silicon-based anode materials are regarded as a key direction to break through the existing technical bottlenecks because their theoretical specific capacity (4200 mAh / g) far exceeds that of traditional graphite (372 mAh / g). SiO x (silicon monoxide, 0 < x < 2) is an important component of silicon-based materials. Although its theoretical specific capacity (1200 - 1500 mAh / g) is lower than that of elemental silicon, it is still much higher than traditional anode materials. Compared with elemental silicon, SiO x has a lower volume expansion rate (about 100 - 200%), which not only reduces the mechanical stress of the electrode material and significantly improves the cycle stability. SiO x achieves a good balance among specific capacity, volume expansion, and cycle stability, and is a highly potential anode material with high energy density. At the same time, SiO x has a relatively low synthesis cost and a wide source, making it widely used in high-energy-density lithium-ion batteries in fields such as consumer electronics and electric vehicles.

[0003] Researchers have also carried out research on its disadvantages and proposed some improvement methods. Among them, materials with special structures are designed to relieve volume changes in order to improve mechanical properties and electrochemical properties. For example, materials with a nanoscale structure improve mechanical properties; composites are formed with materials having high mechanical strength (such as polymers, metals) to enhance their toughness. At the same time, by element doping or compounding with conductive materials, their conductivity can be enhanced. Currently, carbon nanotubes, metal oxides, etc. are usually used to modify SiO x materials; for example, the prior art discloses a Co nanoparticle-modified SiO x / C composite material with stable high capacity, in which sub-nanoscale SiO x clusters are uniformly dispersed in the in-situ formed carbon matrix.

[0004] However, when using carbon nanotubes, metal oxides, etc. for modification, on the one hand, the raw material costs of carbon nanotubes, metal oxides, etc. are relatively high, and the electrochemical performance improvement of the modified SiO x materials is limited; based on this, it is necessary to make improvements thereon. Summary of the Invention

[0005] In order to solve the defects existing in the prior art, the present invention provides a preparation method and application of lithium battery negative electrode materials, and a lithium ion battery. Compared with modified materials such as carbon nanotubes and metal oxides, montmorillonite (MMT) is a natural mineral with abundant reserves and low cost. The present invention adopts MMT as a template, vinyltriethoxysilane (VTES) as a silicon source, and resorcinol as a carbon source, and prepares MMT@SiOx / C composite materials through sol-gel method, oxidative polymerization and high-temperature calcination. The introduction of MMT enhances the interfacial bonding force with the carbon layer, and its natural layered structure can relieve the volume expansion stress of the electrode material. The high specific surface area can adsorb lithium ions and improve the conductivity, effectively improving the SiO x Electrochemical performance of MMT@SiO / C materials. After 500 cycles at 2.0 A / g, x The capacity retention rate of / C is as high as 92.36%, which is much higher than that of SiO x / C capacity retention rate (73.51%).

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a lithium battery negative electrode material, comprising the following steps:

[0008] Dissolve resorcinol in an ethanol aqueous solution, add ammonia water, stir, then add formaldehyde and vinyltriethoxysilane, stir and react to obtain a first precursor;

[0009] The first precursor is calcined under an inert atmosphere to obtain SiO x / C material;

[0010] dispersing hydrogen-based bentonite in water to obtain a suspension;

[0011] Adding hexadecyltrimethylammonium bromide to the suspension, stirring, and performing a hydrothermal reaction to obtain a solid product;

[0012] Dispersing the solid product in an ethanol aqueous solution, adding resorcinol and stirring to dissolve it, then adding ammonia water and stirring, then adding formaldehyde and vinyltriethoxysilane and stirring to react to obtain a second precursor;

[0013] The second precursor was calcined under an inert atmosphere to obtain MMT@SiO x / C composite material, which is the negative electrode material of lithium battery.

[0014] Preferably, the first precursor is calcined at 700-900°C for 3-4 hours under an inert atmosphere to obtain SiO x / C material.

[0015] The second precursor was calcined at 700-900 °C for 3-4 h under an inert atmosphere to obtain MMT@SiO x / C composite materials.

[0016] Preferably, the preparation method of the hydrogen-based bentonite comprises the following steps:

[0017] Sodium bentonite is soaked in sulfuric acid to make H + with Na + An ion exchange reaction occurs, hydrogen-based bentonite.

[0018] Preferably, resorcinol is dissolved in an ethanol aqueous solution, ammonia water is added, and the mixture is stirred for 0.5 to 1 hour, and then formaldehyde and vinyltriethoxysilane are added, and the mixture is stirred and reacted for 24 to 30 hours to obtain a first precursor;

[0019] The mass volume ratio of the resorcinol, ethanol aqueous solution, ammonia water, formaldehyde and vinyltriethoxysilane is (0.1-0.2) g: (28-40) mL: (0.3-0.4) mL: (0.14-0.16) mL: (1-2) mL;

[0020] The mass fraction of the ammonia water is 25-26%;

[0021] The formaldehyde is a formaldehyde aqueous solution with a mass fraction of 37 to 40%;

[0022] The volume ratio of ethanol to water in the ethanol aqueous solution is (20-25):(8-15).

[0023] Preferably, cetyltrimethylammonium bromide is added to the suspension, stirred, and then subjected to a hydrothermal reaction to obtain a solid product, wherein the hydrothermal reaction temperature is 120-130° C. and the time is 1-2 hours.

[0024] Preferably, in the step of dispersing hydrogen-based bentonite in water to obtain a suspension; adding hexadecyltrimethylammonium bromide to the suspension, stirring, and performing a hydrothermal reaction to obtain a solid product; dispersing the solid product in an ethanol aqueous solution, adding resorcinol and stirring to dissolve it, then adding ammonia water and stirring, and then adding formaldehyde and vinyltriethoxysilane and stirring to react to obtain a second precursor, the mass volume ratio of the hydrogen-based bentonite, water, hexadecyltrimethylammonium bromide, ethanol aqueous solution, resorcinol, ammonia water, formaldehyde, and vinyltriethoxysilane is (0.1-0.2) g: (20-25) g: (0.01-0.02) g: (28-40) mL: (0.1-0.2) g: (0.3-0.4) mL: (0.14-0.16) mL: (1-2) mL;

[0025] The mass fraction of the ammonia water is 25-26%;

[0026] The formaldehyde is a formaldehyde aqueous solution with a mass fraction of 37 to 40%;

[0027] The volume ratio of ethanol to water in the ethanol aqueous solution is (20-25):(8-15).

[0028] Preferably, the soaking time is 24 to 30 hours;

[0029] The mass fraction of the sulfuric acid is 18 to 25%;

[0030] The mass volume ratio of the sodium bentonite to sulfuric acid is (0.3-0.4) g: (10-15) mL.

[0031] In a second aspect, the present invention further provides a lithium battery negative electrode material, characterized in that it is prepared using the above-mentioned preparation method.

[0032] In a third aspect, the present invention also provides an application of the lithium battery negative electrode material in the preparation of a lithium battery.

[0033] In a fourth aspect, the present invention further provides a lithium ion battery comprising a negative electrode, wherein the negative electrode comprises a negative electrode current collector and a negative electrode slurry coated on the negative electrode current collector;

[0034] The negative electrode slurry includes a binder, a conductive agent, a solvent, and the lithium battery negative electrode material or the lithium battery negative electrode material prepared by the preparation method.

[0035] In a fifth aspect, the present invention further provides a lithium-ion battery, comprising a positive electrode, wherein the positive electrode is the positive electrode of the lithium-ion battery.

[0036] The preparation method and application of the lithium battery negative electrode material and the lithium ion battery of the present invention have the following effects compared with the prior art:

[0037] 1. The preparation method of the lithium battery negative electrode material of the present invention adopts MMT as a template, vinyltriethoxysilane (VTES) as a silicon source, and resorcinol as a carbon source, and is prepared by a sol-gel method through oxidative polymerization and high-temperature calcination to prepare MMT@SiO x / C composite materials. The introduction of MMT enhances the interfacial bonding strength with the carbon layer. Its natural layered structure can relieve the volume expansion stress of the electrode material. Its high specific surface area can adsorb lithium ions and improve conductivity, effectively improving the SiO x Electrochemical performance of MMT@SiO / C materials. After 500 cycles at 2.0 A / g, x The capacity retention rate of / C is as high as 92.36%, which is much higher than that of SiO x / C capacity retention rate (73.51%). BRIEF DESCRIPTION OF THE DRAWINGS

[0038] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0039] Figure 1 The SiO prepared in Examples 1 to 3 x / C、MMT@SiO x / C XRD pattern;

[0040] Figure 2 The MMT@SiO prepared in Examples 1 to 3 x / C charge and discharge curves after assembly into a battery;

[0041] Figure 3 For HMMT, NaMMT and MMT@SiO in Example 2 x / XRD pattern, adsorption-desorption isotherm, and XPS spectrum of C-800;

[0042] Figure 4 For the SiO in Example 2 x / C-800, HMMT and MMT@SiO x / C-800 morphological characteristics diagram;

[0043] Figure 5 For the SiO in Example 2 x / C-800 and MMT@SiO x / Electrochemical performance of C-800 after assembly into a battery. DETAILED DESCRIPTION

[0044] To facilitate understanding of the present invention, the present invention will be described more fully below in conjunction with the specific embodiments. Preferred embodiments of the present invention are provided in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0045] The description order of the following embodiments does not limit the preferred order of the embodiments. Additionally, in the description of this application, the term "comprising" means "including but not limited to". The various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present invention; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0046] The present invention provides a method for preparing a lithium-ion battery anode material, comprising the following steps:

[0047] S1. Dissolve resorcinol in an ethanol aqueous solution, add ammonia water, stir, and then add formaldehyde and vinyltriethoxysilane, and stir and react to obtain a first precursor;

[0048] S2. Calcinate the precursor under an inert atmosphere to obtain SiO x / C material (0 < x < 2, for example, x = 1.57);

[0049] S3. Disperse amino-bentonite in water to obtain a suspension;

[0050] S4. Add cetyltrimethylammonium bromide to the suspension, stir, and then carry out a hydrothermal reaction to obtain a solid product;

[0051] S5. Disperse the solid product in an ethanol aqueous solution, add resorcinol and stir to dissolve it, then add ammonia water, stir, and then add formaldehyde and vinyltriethoxysilane, and stir and react to obtain a second precursor;

[0052] Calcinate the second precursor under an inert atmosphere to obtain MMT@SiO x / C composite material, which is the lithium-ion battery anode material.

[0053] In some embodiments, calcinate the first precursor under an inert atmosphere at 700 - 900 °C for 3 - 4 h to obtain SiO x / C material.

[0054] In some embodiments, calcinate the second precursor under an inert atmosphere at 700 - 900 °C for 3 - 4 h to obtain MMT@SiO x / C composite material.

[0055] In some embodiments, the inert atmosphere includes, but is not limited to, at least one of nitrogen, helium, neon, and argon.

[0056] In some embodiments, the preparation method of hydrogen bentonite (HMMT) comprises the following steps:

[0057] Sodium bentonite (NaMMT) was soaked in sulfuric acid to make H + with Na + An ion exchange reaction occurs, hydrogen-based bentonite.

[0058] Specifically, sodium bentonite (NaMMT) was immersed in sulfuric acid, during which time the H + Together with Na in NaMMT + An ion exchange reaction occurs, gradually opening up the tightly packed interlayer structure of the montmorillonite (MMT) and increasing the interlayer spacing. After soaking, the mixture is centrifuged and washed with deionized water until neutral to completely remove residual sulfuric acid and other impurities. Finally, the solid is dried to obtain hydrogen-based bentonite.

[0059] In some embodiments, cetyltrimethylammonium bromide is added to the suspension, stirred, and then subjected to a hydrothermal reaction, wherein the hydrothermal reaction temperature is 120-130° C. and the reaction time is 1-2 h.

[0060] In some embodiments, resorcinol is dissolved in an ethanol aqueous solution, ammonia water is added, and the mixture is stirred for 0.5 to 1 hour, and then formaldehyde and vinyltriethoxysilane are added, and the mixture is stirred and reacted for 24 to 30 hours to obtain a first precursor;

[0061] The mass volume ratio of resorcinol, ethanol aqueous solution, ammonia water, formaldehyde and vinyltriethoxysilane is (0.1-0.2) g: (28-40) mL: (0.3-0.4) mL: (0.14-0.16) mL: (1-2) mL;

[0062] The mass fraction of ammonia water is 25-26%;

[0063] Formaldehyde is a formaldehyde aqueous solution with a mass fraction of 37-40%;

[0064] The volume ratio of ethanol to water in the ethanol aqueous solution is (20-25):(8-15).

[0065] In some embodiments, hydrogen bentonite is dispersed in water to obtain a suspension; hexadecyltrimethylammonium bromide is added to the suspension, stirred for 1 to 2 hours, and then subjected to a hydrothermal reaction to obtain a solid product;

[0066] The mass volume ratio of hydrogen bentonite, water and hexadecyltrimethylammonium bromide is (0.1-0.2) g: (20-25) mL: (0.01-0.02) g.

[0067] In some embodiments, hydrogen bentonite is dispersed in water to obtain a suspension; hexadecyltrimethylammonium bromide is added to the suspension, stirred, and then subjected to a hydrothermal reaction to obtain a solid product; the solid product is dispersed in an ethanol aqueous solution, resorcinol is added and stirred to dissolve it, and then ammonia water is added and stirred, and then formaldehyde and vinyltriethoxysilane are added and stirred to react to obtain a second precursor. In the step, the mass volume ratio of hydrogen bentonite, water, hexadecyltrimethylammonium bromide, ethanol aqueous solution, resorcinol, ammonia water, formaldehyde, and vinyltriethoxysilane is (0.1-0.2) g: (20-25) g: (0.01-0.02) g: (28-40) mL: (0.1-0.2) g: (0.3-0.4) mL: (0.14-0.16) mL: (1-2) mL;

[0068] The mass fraction of ammonia water is 25-26%;

[0069] Formaldehyde is a formaldehyde aqueous solution with a mass fraction of 37-40%;

[0070] The volume ratio of ethanol to water in the ethanol aqueous solution is (20-25):(8-15).

[0071] In some embodiments, the soaking time is 24 to 30 hours;

[0072] The mass fraction of sulfuric acid is 18-25%;

[0073] The mass volume ratio of sodium bentonite to sulfuric acid is (0.3-0.4) g: (10-15) mL.

[0074] In some embodiments, a method for preparing a lithium battery negative electrode material comprises the following steps:

[0075] S1、SiO xPreparation of SiO / C: 0.1 g of resorcinol was accurately weighed using a high-precision balance and slowly added to a pre-prepared ethanol-water solution of 20 mL of deionized water and 8 mL of anhydrous ethanol. The mixture was stirred until the resorcinol was fully dissolved. 0.3 mL of 25% ammonia water was then added and stirred for 1 h. Subsequently, 0.14 mL of formaldehyde (specifically, a 37-40% formaldehyde aqueous solution) and 1 mL of vinyltriethoxysilane were slowly added in that order and stirred for 24 h to ensure sufficient reaction. After centrifugation and drying, the precursor was obtained and placed in a vacuum tube furnace. Under argon protection, the temperature was increased at 3°C / min and calcined at 700, 800, and 900°C for 3 h, respectively. Thus, SiO / C was successfully prepared. x / C-700、SiO x / C-800 and SiO x / C-900 three target products;

[0076] S2. Preparation of hydrogen bentonite (HMMT): Accurately weigh 0.3 g of sodium bentonite (NaMMT) and soak it in a 18% sulfuric acid (H2SO4) solution for 24 h. During this period, the H + Together with Na in NaMMT + An ion exchange reaction occurs, gradually opening up the tightly stacked interlayer structure of MMT and increasing the interlayer spacing. After soaking, the mixture is centrifuged and washed with deionized water until neutral to completely remove residual sulfuric acid and other impurities. Finally, the solid is dried to obtain hydrogen-based bentonite.

[0077] S3, MMT@SiO x Preparation of HCl / C: 0.1 g of HMMT was weighed and ultrasonically dispersed in 20 mL of deionized water to form a stable suspension. Subsequently, 0.01 g of hexadecyltrimethylammonium bromide (CTAB) was added to the suspension and stirred for 1 h. Subsequently, the suspension was transferred to a reactor and subjected to a hydrothermal reaction at 120°C for 12 hours. After the hydrothermal reaction, the product was centrifuged to obtain a solid product. The solid product was then redispersed in a pre-prepared ethanol aqueous solution of 20 mL deionized water and 8 mL anhydrous ethanol, 0.1 g of resorcinol was added, and the mixture was stirred until the resorcinol was fully dissolved. 0.3 mL of 25% ammonia water was then added and stirred for 1 hour. Subsequently, 0.14 mL of formaldehyde (specifically, a formaldehyde aqueous solution with a mass fraction of 37-40%) and 1 mL of vinyltriethoxysilane were slowly added in sequence and stirred for 24 hours to ensure sufficient reaction. After centrifugation and drying, the precursor was obtained and placed in a vacuum tube furnace. Under argon protection, the precursor was calcined at 700, 800, and 900°C for 3 hours at a heating rate of 3°C / min. MMT@SiO was successfully prepared.x / C-700、MMT@SiO x / C-800 and MMT@SiO x / C-900 three target products, namely lithium battery negative electrode materials.

[0078] Compared with modified materials such as carbon nanotubes and metal oxides, montmorillonite (MMT) is a natural mineral with abundant reserves, low cost, and simple preparation. The present invention uses MMT as a template, vinyltriethoxysilane (VTES) as a silicon source, and resorcinol as a carbon source. MMT@SiO is prepared by sol-gel method, oxidative polymerization and high-temperature calcination. x / C composite materials. The introduction of MMT enhances the interfacial bonding strength with the carbon layer. Its natural layered structure can relieve the volume expansion stress of the electrode material. Its high specific surface area can adsorb lithium ions and improve conductivity, effectively improving the SiO x Electrochemical performance of MMT@SiO / C materials. After 500 cycles at 2.0 A / g, x The capacity retention rate of / C is as high as 92.36%, which is much higher than that of SiO x / C capacity retention rate (73.51%)

[0079] Based on the same inventive concept, the present invention also provides a lithium battery negative electrode material, which is prepared using the above-mentioned preparation method.

[0080] Based on the same inventive concept, the present invention also provides an application of the above-mentioned lithium battery negative electrode material in the preparation of a lithium battery.

[0081] Based on the same inventive concept, the present invention also provides a lithium ion battery, comprising a negative electrode, the negative electrode comprising a negative electrode current collector and a negative electrode slurry coated on the negative electrode current collector;

[0082] The negative electrode slurry includes a binder, a conductive agent, a solvent, and the lithium battery negative electrode material or the above-mentioned lithium battery negative electrode material prepared by the above-mentioned preparation method.

[0083] Specifically, the above-mentioned lithium battery negative electrode material is used as the negative electrode active material, and the lithium battery negative electrode material, Super P (Super P is conductive carbon black, used as a conductive agent), and CMC (sodium carboxymethyl cellulose, used as a binder) are mixed in a mass ratio of 7:2:1, and then deionized water is added as a solvent. The mixture is stirred in a blender until it becomes a slurry to obtain a negative electrode slurry. The slurry is evenly coated on a copper foil, and the corresponding negative electrode sheet is obtained by vacuum drying and stamping. The mass volume ratio of the lithium battery negative electrode material to water is 0.1g:(0.1~0.15)mL.

[0084] Specifically, the lithium-ion battery of the present invention also includes a diaphragm and an electrolyte. The diaphragm can be a Celgard 2400 PP diaphragm, and the electrolyte is a 1 mol / L LiPF6 electrolyte. Specifically: a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a volume ratio of 1:1:1 is selected as a solvent, lithium hexafluorophosphate is used as a solute (LiPF6), and an electrolyte with a concentration of 1 mol / L is prepared.

[0085] The following further illustrates the preparation method and application of the lithium battery negative electrode material and the lithium-ion battery of the present invention with specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0086] In the following examples, sodium bentonite was purchased from MacLean Biochemical Technology Co., Ltd., CAS: 85049-30-5.

[0087] Example 1

[0088] This embodiment provides a method for preparing a lithium battery negative electrode material, comprising the following steps:

[0089] S1、SiO x Preparation of / C: Use a high-precision balance to accurately weigh 0.1g of resorcinol and slowly add it to a pre-prepared mixed solution of 20mL deionized water and 8mL anhydrous ethanol, stir until the resorcinol is fully dissolved, then add 0.3mL of 25% ammonia water and stir for 1h. Then, slowly add 0.14mL of formaldehyde (specifically, a 37% formaldehyde aqueous solution) and 1mL of vinyltriethoxysilane (VTES) in this order, and continue stirring for 24h to ensure sufficient reaction; after centrifugation and drying, the first precursor is obtained, which is placed in a vacuum tube furnace and, under argon protection, heated to 700℃ at a rate of 3℃ / min and calcined for 3h to obtain SiO x / C-700 material;

[0090] S2. Preparation of hydrogen-based bentonite (HMMT): 0.3 g of sodium bentonite (NaMMT) was accurately weighed and soaked in an 18% by mass sulfuric acid (H2SO4) solution for 24 h. After soaking, the mixture was centrifuged and washed with deionized water until neutral to completely remove residual sulfuric acid and other impurities. Finally, the solid was dried to obtain hydrogen-based bentonite (HMMT);

[0091] S3, MMT@SiO xPreparation of / C: 0.1 g of hydrogenated bentonite (HMMT) was weighed and ultrasonically dispersed in 20 mL of deionized water to form a stable suspension. 0.01 g of cetyltrimethylammonium bromide (CTAB) was then added to the suspension and stirred for 1 hour. The suspension was then transferred to a reactor and subjected to a hydrothermal reaction at 120°C for 12 hours. After the hydrothermal reaction, the product was centrifuged to obtain a solid product.

[0092] S4. The solid product was dispersed in an ethanol aqueous solution of 20 mL deionized water and 8 mL anhydrous ethanol, 0.1 g resorcinol was added, and the mixture was stirred until the resorcinol was fully dissolved. Then, 0.3 mL of 25% ammonia water was added and stirred for 1 h. Then, 0.14 mL of formaldehyde (specifically, a 37% formaldehyde aqueous solution) and 1 mL of vinyltriethoxysilane (VTES) were slowly added in that order and stirred for 24 h to ensure sufficient reaction. After centrifugation and drying, the second precursor was obtained, which was placed in a vacuum tube furnace and heated to 700 ° C at a rate of 3 ° C / min under argon protection. It was calcined for 3 h to successfully prepare MMT@SiO x / C-700, and the lithium battery negative electrode material MMT@SiO x / C-700.

[0093] This embodiment also provides a lithium-ion battery using the lithium battery negative electrode material MMT@SiO x / C-700 is assembled. Specifically, the lithium-ion battery includes a negative electrode plate. The preparation method of the negative electrode plate is as follows: the lithium battery negative electrode material MMT@SiO prepared in Example 1 is x / C-700, Super P, and CMC are mixed in a mass ratio of 7:2:1, and then deionized water is added as a solvent. The mixture is stirred in a blender until it becomes a slurry to obtain a negative electrode slurry. The slurry is evenly coated on a copper foil, and vacuum dried and stamped to obtain the corresponding negative electrode sheet. The mass volume ratio of the lithium battery negative electrode material to water is 0.1g:0.12mL;

[0094] The lithium-ion battery further comprises a positive electrode sheet (specifically a lithium sheet), a diaphragm and an electrolyte; the diaphragm is a Celgard 2400 PP diaphragm, and the electrolyte is a 1 mol / L LiPF6 electrolyte. Specifically, a mixed solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a volume ratio of 1:1:1 is selected as the solvent, and lithium hexafluorophosphate is used as the solute (LiPF6) to prepare an electrolyte with a concentration of 1 mol / L.

[0095] The lithium-ion battery uses a CR2025 battery shell as the outer shell. The above-mentioned negative electrode sheet, positive electrode sheet (specifically lithium sheet), separator, electrolyte, and outer shell are assembled into a button battery in a glove box and the corresponding electrochemical tests are carried out.

[0096] Example 2

[0097] This embodiment provides a method for preparing a lithium battery negative electrode material, which is the same as that of embodiment 1, except that in step S1, the temperature is raised to 800°C at a rate of 3°C / min and calcined for 3h to obtain SiO x / C-800 material; in step S4, the temperature was raised to 800°C at a rate of 3°C / min and calcined for 3h. The other process parameters were the same as those in Example 1, and finally the lithium battery negative electrode material MMT@SiO was prepared. x / C-800.

[0098] This embodiment also provides a lithium-ion battery, which is the same as the embodiment 1, except that the lithium battery negative electrode material MMT@SiO in the embodiment 2 is used. x / C-800 assembly, and the rest are the same as in Example 1.

[0099] Example 3

[0100] This embodiment provides a method for preparing a lithium battery negative electrode material, which is the same as that of embodiment 1, except that in step S1, the temperature is raised to 900°C at a rate of 3°C / min and calcined for 3h to obtain SiO x / C-900 material; in step S4, the temperature is raised to 900°C at a rate of 3°C / min and calcined for 3h. The other process parameters are the same as those in Example 1, and finally the lithium battery negative electrode material MMT@SiO is prepared. x / C-900.

[0101] This embodiment also provides a lithium-ion battery, which is the same as the embodiment 1, except that the lithium battery negative electrode material MMT@SiO in the embodiment 3 is used. x / C-900 assembly, and the rest is the same as in Example 1.

[0102] Performance Testing

[0103] XRD was used to characterize HMMT and SiO at different temperatures. x / C、MMT@SiO x / C was characterized and analyzed, and the results were as follows Figure 1 Specifically, Figure 1 a is HMMT and MMT@SiO prepared in Example 1 x / C-700, MMT@SiO prepared in Example 2 x / C-800 and MMT@SiO prepared in Example 3x / XRD pattern of C-900; Figure 1 b is SiO prepared in Examples 1 to 3 x / C-700、SiO x / C-800 and SiO x / XRD pattern of C-900; Figure 1 c~d are SiO prepared in Example 1 x / C-700、MMT@SiO x / C-700, SiO prepared in Example 2 x / C-800、MMT@SiO x / C-800, SiO prepared in Example 3 x / C-900 and MMT@SiO x / XRD pattern of C-900.

[0104] from Figure 1 As can be seen in Figure a, HMMT has a (011) diffraction peak at 26.7°, which is unique to SiO2. Figure 1 As can be seen in b, SiO x / C-700、SiO x / C-800 and SiO x The XRD patterns of / C-900 show that the amorphous SiO x and broad peaks of amorphous carbon, which means that SiO prepared at 700, 800 and 900 °C x / C shows amorphous characteristics. Further comparison Figure 1 SiO at different temperatures in c~e x / C and MMT@SiO x / C XRD pattern, amorphous SiO x and amorphous carbon peaks. In addition, Figure 1 In a, a (011) characteristic diffraction peak was also observed. These characteristics fully indicate that MMT@SiO x / C material was successfully prepared.

[0105] Figure 2 The charge and discharge curves of batteries assembled from different materials are shown below. Figure 2 Where a is SiO prepared in Examples 1 to 3 x / C-700、MMT@SiO x / C-700、SiO x / C-800、MMT@SiO x / C-800、SiO x / C-900 and MMT@SiOx / Initial charge and discharge curves of C-900 after assembly into a battery; Figure 2 b~e are SiO prepared in Examples 1~3 x / C-700、MMT@SiO x / C-700、SiO x Cycling performance curves of batteries assembled with MMT@SiOx / C-800, MMT@SiOx / C-800, SiOx / C-900, and MMT@SiOx / C-900.

[0106] right Figure 2 The curve shown in a is analyzed, and the specific data are summarized in Table 1 below. The analysis results show that under different temperature conditions, compared with SiO x / C materials, MMT@SiO prepared using MMT as a template x / C materials show better performance. MMT@SiO x The initial charge and discharge capacity of SiO / C was improved. At the same time, the introduction of MMT effectively improved the x / ICE (first coulombic efficiency) of C materials.

[0107] Table 1 - MMT@SiO at different temperatures in Examples 1 to 3 x / C and SiO x Initial charge and discharge results of the battery assembled with C

[0108]

[0109]

[0110] Figure 2 b to d show the SiO x / C and MMT@SiO x The cycling performance curves of MMT@SiO2 / C materials at 0.5A / g under calcination conditions of 700℃, 800℃ and 900℃ are shown in Figure 2. The data show that at all test temperatures, the MMT@SiO2 prepared by the MMT template method has a good cycling performance. x The cycling performance of / C materials is significantly better than that of SiO x / C materials, confirming that the introduction of MMT improves the SiO x / C cyclability. Comparison of MMT@SiO at different temperatures x / C material cycle performance, such as Figure 2 As shown in Figure e, it is found that the sample cycle performance is best at 800℃. Based on this, 800℃ is determined to be the optimal calcination temperature, and SiO x / C-800 and MMT@SiO x / C-800 conducts subsequent system testing to further analyze the effect of MMT on SiO x / C material performance improvement mechanism.

[0111] The NaMMT, HMMT and MMT@SiO x -800 was characterized to determine the SiO x The growth of / C on the MMT template is shown in the following figure. Figure 3 shown.

[0112] Specifically, Figure 3 a in the table represents HMMT, NaMMT and MMT@SiO x / C-800, b is the XRD pattern of HMMT, NaMMT and MMT@SiO x / C-800 adsorption-desorption isotherms, c for HMMT, NaMMT and MMT@SiO x / C-800 pore size distribution, d is SiO x / C-800 and MMT@SiO x XPS spectrum of / C-800 (d is C1s spectrum and e is Si 2p spectrum).

[0113] Specifically, Figure 3 a in the table represents HMMT, NaMMT and MMT@SiO x / C-80 XRD pattern. According to the Bragg equation:

[0114] 2d sinθ=nλ;

[0115] Where λ is the wavelength of the incident X-ray, which is 0.15418nm (Cu Kα), and θ is the angle between the X-ray and the sample plane. Comparing the XRD patterns of NaMMT and HMMT, it was found that after acidification, the diffraction peak of one crystal plane of NaMMT shifted leftward from 7.10° to 5.78°, and the interlayer spacing d increased from 1.2440nm to 1.5278nm. This phenomenon is attributed to the fact that when H + Ion exchange Na + After that, the interlayer molecular force increases, which triggers the interlayer hydration expansion effect. The BET and BJH methods are further used to analyze the changes in the specific surface area and the evolution of the pore structure of the material, such as Figure 3 As shown in b and c, the specific surface area of ​​NaMMT was found to be 44.2 m 2 / g, with an average pore width of 8.9nm; after acidification, the specific surface area of ​​HMMT increased to 76.7m 2 / g, the average pore width is reduced to 5.7nm. This result shows that the acidification process destroys the interlayer ionic bonding, which promotes the opening of the interlayer structure of MMT and forms a richer pore structure. This structure is transformed into the subsequent SiOx The in-situ growth of / C materials provides an ideal template environment.

[0116] Comparison with MMT@SiO x XRD patterns of MMT@SiO x The diffraction peak of / C-800 at 5-8° disappears, indicating that the interlayer spacing shrinks from 1.5278nm of HMMT to an amorphous structure, and the interlayer structure is destroyed. This result indicates that SiO x / C grows in the interlayer structure of MMT. Similarly, comparing the adsorption-desorption isotherms and pore size distribution curves of the two, it is observed that HMMT presents a typical IV type adsorption-desorption isotherm, and there is an obvious hysteresis loop in the P / P0 range of 0.45-1.0, indicating that it has a large number of mesoporous structures. x The isotherm at -800°C turns into type I and the hysteresis loop disappears completely, indicating that the pore structure on the MMT template can be used as a SiO x / C growth site. MMT@SiO x The specific surface area and pore width of / -800 are 84.2m 2 / g and 2.5nm, the specific surface area increases and the pore width decreases, indicating that SiO x The in-situ growth of / C destroys the original interlayer structure of MMT and constructs a more stable pore network.

[0117] Figure 3 d~e are SiO x / C-800 and MMT@SiO x XPS spectrum of / C-800. In the C1s spectrum, characteristic peaks were observed at CC (284.8eV), CO (285.8eV) and C=O (289.5eV). In the Si 2p spectrum, characteristic peaks were observed at Si 2+ (102.5eV), Si 3+ (103.2eV) and Si 4+ The characteristic peak at 104.0 eV is shown in Table 2. Based on the area of ​​each valence state of Si in the Si 2p spectrum, the average valence state of Si and the unknown quantity x in the chemical formula can be calculated.

[0118] Table 2 - SiO x / C-800 and MMT@SiO x XPS results of / C-800

[0119] sample <![CDATA[Si 2+ Content (%)]]> <![CDATA[Si 3+ Content (%)]]> <![CDATA[Si 4+ Content (%)]]> Si average valence O content (x) <![CDATA[MMT@SiO x / C-800]]> 21.05 44.98 33.97 3.13 1.57 <![CDATA[SiO x / C-800]]> 16.50 54.46 29.04 3.13 1.57

[0120] It can be seen from Table 2 that in SiO x / C-800 and MMT@SiO x In / C-800, the average valence of Si is 3.13 and the unknown quantity x is 1.57. x The existence form is the same, both are SiO 1.57 , but the content of Si in each valence state is different.

[0121] The SEM technique was used to characterize the SiO x / C-800, HMMT and MMT@SiO x / C-800 morphological characteristics, the results are as follows Figure 4 shown.

[0122] Specifically, Figure 4 a and d are SiO x SEM images of / C-800 at different magnifications, b and e are SEM images of HMMT, c and f are SEM images of MMT@SiO x SEM image of / C-800.

[0123] from Figure 4 It can be clearly seen in a and d that SiO x / C-800 material mainly appears in the form of microspheres with a particle size of approximately 400 to 500 nm. Figure 4 In b and e, it is clearly shown that HMMT presents a layered structure, and this structure is exactly SiO x / C material growth template. Further observation Figure 4 In c and f, it can be observed that the layered structure of the MMT template has been x / C material filling. However, Figure 4 The red dotted areas in c and f show that the filled MMT@SiO x There are still some exposed MMT structures in the C-800 material. These exposed parts can be used as contact points with the electrolyte, which is beneficial to the Li + At the same time, compared with the smooth surface of HMMT, MMT@SiO x / C-800 has a relatively rough surface with many tiny microspheres. This difference fully demonstrates that SiO x / C materials were successfully grown on the MMT template.

[0124] Figure 5 For the SiO in Example 2 x / C-800 and MMT@SiO x / C-800 assembled into a battery after the electrochemical performance, specifically, at 0.5A / g ( Figure 5 a), 1.0A / g( Figure 5 b), 2.0A / g( Figure 5 c), 5.0A / g( Figure 5 Cycling performance and rate performance under (d) Figure 5 e, specifically, the rate performance at 0.1 A / g, 0.2 A / g, 0.5 A / g, 1.0 A / g, 2.0 A / g, 5.0 A / g, and 10 A / g).

[0125] from Figure 5 It can be clearly observed in a-c that at 0.5A / g, 1.0A / g and 2.0A / g, MMT@SiO x The cycle performance of batteries assembled with SiO x / C-800, indicating that the introduction of MMT can improve the SiO x / C-800. In particular, at 2.0 A / g, after 500 cycles, MMT@SiO x The capacity retention rate of the battery assembled with SiO2 / C-800 is as high as 92.36%, while x The capacity retention rate of / C-800 assembly is only 73.51%, which is a significant difference. Figure 5 In the middle d, MMT@SiO x After 1500 cycles at 5.0 A / g, the capacity of / C-800 did not decay. This phenomenon proves that the introduction of MMT can improve the SiO x / C-800 cyclic stability. In addition, Figure 5 The rate test results of the middle e show that the introduction of MMT can improve the SiO x / C-800 rate performance.

[0126] It can be understood that the various technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0127] The above are merely preferred embodiments of the present application and only specifically describe the technical principles of the present application. These descriptions are intended only to explain the principles of the present application and should not be construed in any way as limiting the scope of protection of the present application. Based on the explanations herein, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present application, as well as other specific implementations of the present application that can be conceived by those skilled in the art without inventive effort, shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a lithium battery negative electrode material, characterized in that: The following steps are involved: Dissolve resorcinol in an ethanol aqueous solution, add ammonia water, stir, then add formaldehyde and vinyltriethoxysilane, stir and react to obtain a first precursor; The first precursor is calcined under an inert atmosphere to obtain SiO x / C material; dispersing hydrogen-based bentonite in water to obtain a suspension; Adding hexadecyltrimethylammonium bromide to the suspension, stirring, and performing a hydrothermal reaction to obtain a solid product; Dispersing the solid product in an ethanol aqueous solution, adding resorcinol and stirring to dissolve it, then adding ammonia water and stirring, then adding formaldehyde and vinyltriethoxysilane and stirring to react to obtain a second precursor; The second precursor was calcined under an inert atmosphere to obtain MMT@SiO x / C composite material, which is the negative electrode material of lithium battery.

2. The method for preparing a lithium battery negative electrode material according to claim 1, wherein: The first precursor is calcined at 700-900°C for 3-4 hours under an inert atmosphere to obtain SiO x / C material. The second precursor was calcined at 700-900 °C for 3-4 h under an inert atmosphere to obtain MMT@SiO x / C composite materials.

3. The method for preparing a lithium battery negative electrode material according to claim 1, wherein: The preparation method of the hydrogen-based bentonite comprises the following steps: Sodium bentonite is soaked in sulfuric acid to make H + with Na + An ion exchange reaction occurs, hydrogen-based bentonite.

4. The method for preparing a lithium battery negative electrode material according to claim 1, wherein: Dissolve resorcinol in an ethanol aqueous solution, add ammonia water, stir for 0.5 to 1 hour, then add formaldehyde and vinyltriethoxysilane, stir and react for 24 to 30 hours to obtain a first precursor; The mass volume ratio of the resorcinol, ethanol aqueous solution, ammonia water, formaldehyde and vinyltriethoxysilane is (0.1-0.2) g: (28-40) mL: (0.3-0.4) mL: (0.14-0.16) mL: (1-2) mL; The mass fraction of the ammonia water is 25-26%; The formaldehyde is a formaldehyde aqueous solution with a mass fraction of 37 to 40%; The volume ratio of ethanol to water in the ethanol aqueous solution is (20-25):(8-15).

5. The method for preparing a lithium battery negative electrode material according to claim 1, wherein: Hexadecyltrimethylammonium bromide is added to the suspension, and after stirring, a hydrothermal reaction is carried out to obtain a solid product, wherein the hydrothermal reaction temperature is 120-130° C. and the time is 1-2 hours.

6. The method for preparing a lithium battery negative electrode material according to claim 1, wherein: Dispersing hydrogen-based bentonite in water to obtain a suspension; adding hexadecyltrimethylammonium bromide to the suspension, stirring, and performing a hydrothermal reaction to obtain a solid product; dispersing the solid product in an ethanol aqueous solution, adding resorcinol and stirring to dissolve it, then adding ammonia water and stirring, and then adding formaldehyde and vinyltriethoxysilane and stirring to react to obtain a second precursor, wherein the mass volume ratio of the hydrogen-based bentonite, water, hexadecyltrimethylammonium bromide, ethanol aqueous solution, resorcinol, ammonia water, formaldehyde, and vinyltriethoxysilane is (0.1-0.2) g: (20-25) g: (0.01-0.02) g: (28-40) mL: (0.1-0.2) g: (0.3-0.4) mL: (0.14-0.16) mL: (1-2) mL; The mass fraction of the ammonia water is 25-26%; The formaldehyde is a formaldehyde aqueous solution with a mass fraction of 37 to 40%; The volume ratio of ethanol to water in the ethanol aqueous solution is (20-25):(8-15).

7. The method for preparing a lithium battery negative electrode material according to claim 3, wherein: The soaking time is 24 to 30 hours; The mass fraction of the sulfuric acid is 18 to 25%; The mass volume ratio of the sodium bentonite to sulfuric acid is (0.3-0.4) g: (10-15) mL.

8. A lithium battery negative electrode material, characterized in that The preparation method is as described in any one of claims 1 to 7.

9. Use of the lithium battery negative electrode material according to claim 8 in the preparation of a lithium battery.

10. A lithium ion battery, characterized in that: The negative electrode comprises a negative electrode current collector and a negative electrode slurry coated on the negative electrode current collector; The negative electrode slurry comprises a binder, a conductive agent, a solvent, and a lithium battery negative electrode material prepared by the preparation method according to any one of claims 1 to 7 or the lithium battery negative electrode material according to claim 8.

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