Lithium battery negative electrode material, lithium battery and preparation method

Abstract

The application relates to a lithium battery negative electrode material, a lithium battery and a preparation method. The lithium battery negative electrode material comprises zirconium dioxide and carbon particles arranged in the zirconium dioxide, silicon is arranged in the carbon particles, and an amorphous carbon layer is arranged on the surface of the carbon particles. The application further provides a preparation method of the lithium battery negative electrode material, which comprises the following steps: mixing and grinding silicon, carbon particles and amorphous carbon raw materials to obtain a silicon / carbon composite precursor, then performing heat treatment to obtain a silicon / carbon composite material; adding a dispersing agent and a block copolymer into a zirconium salt to obtain a zirconium dioxide precursor sol; dispersing the silicon / carbon composite material in the zirconium dioxide precursor sol to obtain a silicon / carbon / zirconium dioxide composite precursor, and then performing calcination to obtain the lithium battery negative electrode material. The application further provides a lithium battery, wherein the negative electrode active material of the lithium battery is the lithium battery negative electrode material. The application solves the problems that the existing lithium battery negative electrode material has large volume expansion in the charging process, and the active material is separated from the current collector due to the charging and discharging cycles.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically to a lithium battery anode material, a lithium battery, and a preparation method thereof. Background Technology

[0002] Lithium-ion batteries possess excellent properties such as high operating voltage, high energy density, long lifespan, wide operating temperature range, and no memory effect.

[0003] Lithium-ion batteries have been widely used in fields such as new energy vehicles. However, as consumers' demands for longer battery life continue to increase, developing batteries with higher specific capacity and higher energy density has become an important area of ​​research. Currently, the main factor limiting further improvements in the capacity and energy of lithium-ion batteries is that the capacity of mainstream graphite-based anode materials has already approached their theoretical specific capacity of 372 mAh / g, making it difficult to further increase the specific capacity from the material itself. Therefore, seeking lithium-ion battery anode materials with higher specific capacity has become crucial for developing battery products with higher specific capacity and higher energy density.

[0004] Silicon has garnered significant attention from researchers due to its theoretical lithium storage capacity of 4200 mAh / g, low lithium insertion / extraction potential, abundant reserves, and low cost. However, its large-scale application in lithium-ion battery anodes is currently limited, primarily due to severe volume changes during lithium insertion / extraction. This characteristic leads to two main issues when used as an anode material: firstly, structural damage and mechanical pulverization cause separation of the anode material from the current collector, resulting in a physical decrease in battery capacity and cycle performance; secondly, volume expansion and contraction cause continuous rupture and reconstruction of the SEI film, continuously consuming active material and contributing to capacity decay and cycle performance degradation. Therefore, silicon is not yet ready for large-scale application as a battery anode material. However, the combination of comprehensive technical research on graphite anode materials and the high lithium storage capacity of silicon has led to increased interest in silicon / carbon composite materials among researchers.

[0005] CN104766958A discloses a silicon-carbon composite material and its preparation method. Specifically, it discloses first obtaining a mixture of silicon and an organic carbon precursor in a high-pressure reactor, then obtaining a composite material in a depressurized sealed container where the organic carbon precursor coats the silicon-based material, and finally carbonizing at high temperature to obtain the silicon-carbon composite material. This method utilizes the high lithium storage capacity of silicon to improve the lithium storage capacity of the lithium-ion battery anode material, while the carbon coating alleviates the volume expansion of silicon during charging to some extent. However, the effect of carbon coating alone in suppressing silicon volume expansion is limited, and there is still a significant risk of separation from the current collector after long-term charge-discharge cycles.

[0006] CN105470474A discloses a composite anode material for high-capacity lithium-ion batteries and its preparation method. It discloses obtaining a silicon-carbon composite material through mechanical ball milling and stirring, and controlling the polymerization reaction of related reactants under ice-water bath conditions to obtain a novel lithium-ion battery anode composite material with a silicon-carbon composite core and two coating materials of amorphous carbon and polyaniline, respectively. While this method suppresses the volume expansion of the silicon-carbon composite material during charge-discharge processes to some extent through the two coating materials, the presence of conjugated large π bonds results in low mechanical properties and difficulty in processing of polyaniline. Furthermore, polyaniline has poor thermal stability, is prone to decomposition at high temperatures, and exhibits poor conductivity and cycling performance. Therefore, using polyaniline as the second coating material poses safety risks, and there is still a significant risk of separation from the current collector after prolonged charge-discharge cycles. Summary of the Invention

[0007] The purpose of this invention is to provide a lithium battery anode material, a lithium battery, and a preparation method to solve the problems of low lithium storage capacity, large volume expansion of silicon during charging, and easy separation of active material and current collector due to long-term charge-discharge cycles in existing lithium battery anode materials.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A lithium battery anode material includes zirconium dioxide and carbon particles embedded in the pores of zirconium dioxide, wherein nano-silicon is embedded in the pores of the carbon particles, and the surface of the carbon particles is coated with an amorphous carbon layer.

[0010] Based on the above technical means, by embedding nano-silicon material with a theoretical lithium intercalation capacity of up to 4200 mAh / g in the inner pores of carbon particles, the lithium storage capacity of the lithium battery anode material is effectively improved. The relatively soft texture of the carbon particles buffers the volume change of silicon during cycling to a certain extent, effectively solving the problem of severe volume expansion of silicon during charging. Coating the surface of the carbon particles with an amorphous carbon layer improves the interface stability of the lithium battery anode material, effectively solving the problem of continuous SEI rupture and regeneration caused by volume changes in silicon material during charging and discharging, leading to capacity reduction. Embedding carbon particles coated with an amorphous carbon layer in loose and porous zirconium dioxide further suppresses the volume change of the anode active material during charging and discharging, while solving the problem of separation of the anode active material from the current collector due to volume changes after long-term charge-discharge cycles. Furthermore, due to the low ductility of zirconium dioxide, it can effectively suppress volume changes within the pores, and the loose and porous structure provides an effective channel for lithium ion insertion / extraction. Furthermore, experiments have shown that after the lithium battery anode material of the present invention is coated onto the current collector, the zirconium dioxide material has extremely low volume change, thus it can always maintain a stable bond with the current collector. This allows the lithium battery anode material as a whole to effectively suppress the problem of separation from the current collector caused by the volume change of the silicon-carbon active material.

[0011] Preferably, in the negative electrode material, by mass percentage, zirconium dioxide is 5-20%, carbon particles are 50-80%, nano-silicon is 10-15%, and amorphous carbon layer is 5-15%.

[0012] Preferably, the carbon particles have a particle size of 1~10μm, the nano-silicon particles have a particle size of 10~100nm, and the amorphous carbon layer has a thickness of ≤1μm.

[0013] The present invention also provides a method for preparing the lithium battery anode material as described herein, comprising the following steps:

[0014] Silicon powder, carbon particles, amorphous carbon raw materials and dispersant are mixed and then ground to obtain a silicon / carbon composite precursor.

[0015] Under an inert atmosphere, the silicon / carbon composite precursor was heat-treated at a temperature of 500~600℃, and then the temperature was lowered to room temperature and ground to obtain the silicon / carbon composite material.

[0016] A dispersant and a surfactant block copolymer were added to a zirconium salt to obtain a zirconium dioxide precursor sol.

[0017] The silicon / carbon composite material was dispersed in a zirconium dioxide precursor sol to obtain a silicon / carbon / zirconium dioxide composite precursor.

[0018] The silicon / carbon / zirconium dioxide composite precursor was calcined to obtain the lithium battery anode material.

[0019] Preferably, the process of cooling the temperature to room temperature includes a programmed cooling to 250°C to 350°C followed by natural cooling to room temperature, wherein the programmed cooling rate is 4-10°C / min.

[0020] Experimental studies have shown that if the composite material is cooled naturally from 500-600℃, the cooling rate will be too fast, resulting in uneven shrinkage between the components and thus easily causing the composite material to fail.

[0021] Preferably, the zirconium salt is selected from ZrOCl2-8H2O, C 24 H 20 O 28 One or more of Zr3, C6H8O7Zr, Zr(NO3)4 and Zr(NO3)4-5H2O.

[0022] Preferably, the heat treatment is a heat treatment at a temperature of 500~600℃ for 5~7 hours, so that amorphous carbon is uniformly coated on the surface of the silicon-carbon composite particle material.

[0023] The calcination temperature is 400℃~550℃.

[0024] The purpose of calcination is to decompose the silicon / carbon / zirconium dioxide composite precursor to obtain a loose zirconium dioxide material.

[0025] Preferably, the particle size of the silicon powder is between 1 and 4 μm;

[0026] The carbon particles are selected from graphite;

[0027] The amorphous carbon raw material is selected from one or more of epoxy resin, phenolic resin and glucose;

[0028] The dispersant is selected from one or more of ethanol, ethylene glycol, and acetone;

[0029] The surfactant block copolymer is selected from polyethylene-butadiene copolymer, styrene-butadiene-chloropropylene copolymer or other multiblock copolymers; wherein, the block copolymer has the properties of being both oil- and water-soluble, thereby effectively promoting the uniform dispersion of the silicon / carbon composite material in the loose pores of zirconium dioxide and avoiding agglomeration;

[0030] The inert atmosphere is selected from one or more of argon, nitrogen, and helium.

[0031] The graphite used is artificial graphite. The dispersant plays an auxiliary role in ensuring the uniform dispersion of the raw materials.

[0032] Preferably, the process further includes drying before calcination and grinding after calcination; the drying temperature is 40~60℃ and the drying time is 10~12h; the particle size of the lithium battery anode material obtained by the grinding process is between 10~40μm.

[0033] The purpose of drying before calcination is to promote the diffusion of zirconium dioxide precursor by allowing it to stand at a temperature higher than room temperature, so that it can more uniformly coat the silicon / carbon composite material.

[0034] The present invention also provides a lithium battery, wherein the negative electrode active material of the lithium battery is the negative electrode material of the present invention.

[0035] The present invention also provides a method for preparing a lithium battery as described herein, comprising the following steps:

[0036] 1) Using lithium metal sheets as the positive electrode;

[0037] 2) Using the lithium battery negative electrode material as the negative electrode active material, negative electrode conductive agent and negative electrode binder, the mixture is mixed, homogenized, coated, rolled and sheeted to obtain a negative electrode sheet;

[0038] 3) Stack the negative electrode shell, gasket, negative electrode sheet, separator, positive electrode sheet, separator, gasket, spring sheet, and positive electrode shell in that order, inject electrolyte, and complete the button cell assembly in a glove box to obtain a button lithium battery.

[0039] Preferably, the negative electrode conductive agent is selected from one or more of conductive carbon black, graphene, carbon nanotubes, conductive graphite, and carbon fiber;

[0040] The negative electrode binder is selected from one or more of sodium carboxymethyl cellulose, styrene-butadiene rubber, sodium alginate, conductive polymer polyacrylonitrile, hydroxymethyl chitosan, polyacrylic acid, and polyvinyl alcohol;

[0041] The electrolyte is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, and lithium perchlorate electrolytes.

[0042] The beneficial effects of this invention are:

[0043] 1) The lithium battery anode material of the present invention effectively improves the lithium storage capacity of the lithium battery anode material by embedding high lithium intercalation capacity nano-silicon material in the inner pores of carbon particles; the relatively soft texture of carbon particles buffers the volume change of silicon during cycling to a certain extent, effectively solving the problem of severe volume expansion of silicon during charging; the amorphous carbon layer coated on the surface of carbon particles improves the interface stability of the lithium battery anode material, effectively solving the problem of capacity reduction caused by the continuous cracking and regeneration of SEI due to volume change of silicon material during charging and discharging; the carbon particles coated with amorphous carbon layer are embedded in loose and porous zirconium dioxide, further suppressing the volume change of the anode active material during charging and discharging, and solving the problem of separation of the anode active material from the current collector due to volume change after long-term charge and discharge cycles. Moreover, due to the low ductility of zirconium dioxide, it can effectively suppress the volume change inside the pores, and the loose and porous structure can provide an effective channel for lithium ion insertion / extraction. Furthermore, experiments have shown that after the lithium battery anode material of the present invention is coated onto the current collector, the zirconium dioxide material has extremely low volume change, thus it can always maintain a stable bond with the current collector, which enables the lithium battery anode material as a whole to effectively suppress the problem of separation from the current collector caused by the volume change of the silicon-carbon active material.

[0044] 2) The method for preparing the lithium battery anode material of the present invention involves mixing and grinding silicon powder, carbon particles, and amorphous carbon raw materials, followed by heat treatment and then a programmed cooling process to ensure uniform shrinkage of the silicon / carbon composite material, thereby effectively guaranteeing its performance. By adding a surfactant block copolymer during the mixing of the silicon / carbon composite material and zirconium dioxide, the surfactant block copolymer, possessing both oleophilic and hydrophilic properties, promotes uniform dispersion of the silicon / carbon composite material within the porous pores of zirconium dioxide. Furthermore, by calcining the silicon / carbon / zirconium dioxide composite precursor to decompose it into porous zirconium dioxide material, the overall electrochemical performance of the lithium battery anode material is effectively guaranteed. The preparation method is simple to operate, has mild process conditions, and is easy to industrialize, making it valuable for widespread application in the field of lithium-ion battery technology. Attached Figure Description

[0045] Figure 1 This is a flowchart of the preparation method of the lithium battery anode material of the present invention;

[0046] Figure 2 This is a schematic diagram of the structure of the lithium battery anode material of the present invention. Detailed Implementation

[0047] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0048] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0049] Numerous details are explored in the following description to provide a more thorough explanation of embodiments of this application; however, it will be apparent to those skilled in the art that embodiments of this application may be implemented without these specific details.

[0050] Example 1

[0051] like Figure 1 As shown, a method for preparing a lithium battery anode material includes the following steps:

[0052] S1. Take 200g of silicon powder raw material with a D50 of 2μm and place it in 250mL of anhydrous ethanol, and stir until a suspension is formed; ball mill the suspension at a speed of 2500r / min, and then sieve it to make the silicon powder particle size between 10~100nm; place the silicon powder in a vacuum drying oven and dry it at a drying temperature of 70℃;

[0053] S2. Take 800g of graphite raw material and ball mill it at a speed of 2000r / min to make the graphite particle size between 1~10μm; then add the dried silicon powder, 150g of phenolic resin and 1200mL of anhydrous ethanol from S1, and then ball mill it at a speed of 300r / min to mix it evenly to obtain the silicon / carbon composite precursor.

[0054] S3. The silicon / carbon composite precursor obtained in S2 is placed in a high-temperature furnace, protected by nitrogen, and kept at 500℃ for 7 hours. Then, it is cooled to 250℃ at a rate of 6℃ / min, and then naturally cooled to room temperature. After crushing and sieving, the silicon / carbon composite material is obtained.

[0055] S4. Mix 300 mL of 0.25 mol / L ZrOCl2-8H2O hydrate, 150 mL of anhydrous ethanol and 15 g of polyethylene-butadiene copolymer and stir rapidly until the solution becomes viscous to obtain zirconium dioxide precursor sol.

[0056] S5. When the zirconium dioxide precursor sol in S4 is stirred until it becomes viscous, add the silicon / carbon composite material prepared in S3. After processing with a high-speed disperser, a uniformly dispersed silicon / carbon / zirconium dioxide composite precursor is obtained.

[0057] S6. The silicon / carbon / zirconium dioxide composite precursor obtained in S5 is placed in a drying oven and stored at 70°C for 10 hours. Then, it is calcined in an air furnace at 500°C. The calcined material is then ball-milled and sieved to obtain a powdered lithium battery anode material with a particle size of 10~40μm.

[0058] Example 2

[0059] like Figure 1 As shown, a method for preparing a lithium battery anode material includes the following steps:

[0060] S1. Take 200g of silicon powder raw material with a D50 of 2μm and place it in 250mL of anhydrous ethanol, and stir until a suspension is formed; ball mill the suspension at a speed of 2500r / min, and then sieve it to make the silicon powder particle size between 10~100nm; place the silicon powder in a vacuum drying oven and dry it at a drying temperature of 65℃;

[0061] S2. Take 800g of graphite raw material and ball mill it at a speed of 2000r / min to make the graphite particle size between 1~10μm; then add the dried silicon powder, 150g of glucose and 1200mL of anhydrous ethanol from S1, and then ball mill it at a speed of 300r / min to mix it evenly to obtain the silicon / carbon composite precursor.

[0062] S3. The silicon / carbon composite precursor obtained in S2 is placed in a high-temperature furnace, protected by argon gas, and kept at 450℃ for 5 hours. Then, it is cooled to 320℃ at a rate of 5℃ / min, and then naturally cooled to room temperature. After crushing and sieving, the silicon / carbon composite material is obtained.

[0063] S4. Mix 300 mL of 0.25 mol / L ZrOCl2-8H2O hydrate, 150 mL of anhydrous ethanol and 15 g of styrene-butadiene-chloropropylene copolymer and stir rapidly until the solution becomes viscous to obtain zirconium dioxide precursor sol.

[0064] S5. When the zirconium dioxide precursor sol in S4 is stirred until it becomes viscous, add the silicon / carbon composite material prepared in S3. After processing with a high-speed disperser, a uniformly dispersed silicon / carbon / zirconium dioxide composite precursor is obtained.

[0065] S6. The silicon / carbon / zirconium dioxide composite precursor obtained in S5 is placed in a drying oven and stored at 70°C for 9 hours. Then, it is calcined in an air furnace at 460°C. The calcined material is then ball-milled and sieved to obtain a powdered lithium battery anode material with a particle size of 10~40μm.

[0066] Example 3

[0067] like Figure 1 As shown, a method for preparing a lithium battery anode material includes the following steps:

[0068] S1. Take 250g of silicon powder raw material with a D50 of 2μm and place it in 300mL of anhydrous ethanol, stirring until a suspension is formed; ball mill the suspension at a speed of 2500r / min, and then sieve it to make the silicon powder particle size between 10~100nm; place the silicon powder in a vacuum drying oven and dry it at a drying temperature of 65℃;

[0069] S2. Take 800g of graphite raw material and ball mill it at a speed of 2000r / min to make the graphite particle size between 1~10μm; then add the dried silicon powder, 160g of glucose and 1300mL of anhydrous ethanol from S1, and then ball mill it at a speed of 300r / min to mix it evenly to obtain the silicon / carbon composite precursor.

[0070] S3. The silicon / carbon composite precursor obtained in S2 is placed in a high-temperature furnace, protected by argon gas, and kept at 600℃ for 7 hours. Then, it is cooled to 320℃ at a rate of 5℃ / min, and then naturally cooled to room temperature. After crushing and sieving, the silicon / carbon composite material is obtained.

[0071] S4. Mix 300 mL of 0.25 mol / L ZrOCl2-8H2O hydrate, 160 mL of anhydrous ethanol and 16 g of styrene-butadiene-chloropropylene copolymer and stir rapidly until the solution becomes viscous to obtain zirconium dioxide precursor sol.

[0072] S5. When the zirconium dioxide precursor sol in S4 is stirred until it becomes viscous, add the silicon / carbon composite material prepared in S3. After processing with a high-speed disperser, a uniformly dispersed silicon / carbon / zirconium dioxide composite precursor is obtained.

[0073] S6. The silicon / carbon / zirconium dioxide composite precursor obtained in S5 is placed in a drying oven and stored at 70°C for 9 hours. Then, it is calcined in an air furnace at 400°C. The calcined material is then ball-milled and sieved to obtain a powdered lithium battery anode material with a particle size of 10~40μm.

[0074] Example 4

[0075] like Figure 1 As shown, a method for preparing a lithium battery anode material includes the following steps:

[0076] S1. Take 200g of silicon powder raw material with D50 of 2μm and place it in 300mL of anhydrous ethanol, and stir until a suspension is formed. Ball mill the suspension at a speed of 2500r / min, and then sieve it to make the silicon powder particle size between 10~100nm. Place the silicon powder in a vacuum drying oven and dry it at a drying temperature of 65℃.

[0077] S2. Take 850g of graphite raw material and ball mill it at a speed of 2000r / min to make the graphite particle size between 1~10μm.

[0078] Then, the dried silicon powder from S1, 160g of glucose and 1350mL of anhydrous ethanol were added, and the mixture was then ball-milled at 300r / min to obtain a silicon / carbon composite precursor.

[0079] S3. The silicon / carbon composite precursor obtained in S2 is placed in a high-temperature furnace, protected by argon gas, and kept at 600℃ for 7 hours. Then, it is cooled to 320℃ at a rate of 5℃ / min, and then naturally cooled to room temperature. After crushing and sieving, the silicon / carbon composite material is obtained.

[0080] S4. Add 280 mL of 0.25 mol / L C 24 H 20 O 28 Zr3, 160 mL of anhydrous ethanol and 16 g of styrene-butadiene-chloropropylene copolymer were mixed and stirred rapidly until the solution became viscous to obtain zirconium dioxide precursor sol.

[0081] S5. When the zirconium dioxide precursor sol in S4 is stirred until it becomes viscous, add the silicon / carbon composite material prepared in S3. After processing with a high-speed disperser, a uniformly dispersed silicon / carbon / zirconium dioxide composite precursor is obtained.

[0082] S6. The silicon / carbon / zirconium dioxide composite precursor obtained in S5 is placed in a drying oven and stored at 70°C for 9 hours. Then, it is calcined in an air furnace at 400°C. The calcined material is then ball-milled and sieved to obtain a powdered lithium battery anode material with a particle size of 10~40μm.

[0083] Example 5

[0084] like Figure 1 As shown, a method for preparing a lithium battery anode material includes the following steps:

[0085] S1. Take 250g of silicon powder raw material with a D50 of 2μm and place it in 300mL of anhydrous ethanol, stirring until a suspension is formed; ball mill the suspension at a speed of 2500r / min, and then sieve it to make the silicon powder particle size between 10~100nm; place the silicon powder in a vacuum drying oven and dry it at a drying temperature of 65℃;

[0086] S2. Take 820g of graphite raw material and ball mill it at a speed of 2000r / min to make the graphite particle size between 1~10μm; then add the dried silicon powder, 160g of glucose and 1300mL of anhydrous ethanol from S1, and then ball mill it at a speed of 300r / min to mix it evenly to obtain the silicon / carbon composite precursor.

[0087] S3. The silicon / carbon composite precursor obtained in S2 is placed in a high-temperature furnace, protected by argon gas, and kept at 600℃ for 7 hours. Then, it is cooled to 320℃ at a rate of 5℃ / min, and then naturally cooled to room temperature. After crushing and sieving, the silicon / carbon composite material is obtained.

[0088] S4. Mix 300 mL of 0.25 mol / L C6H8O7Zr, 160 mL of anhydrous ethanol and 16 g of styrene-butadiene-chloropropylene copolymer and stir rapidly until the solution becomes viscous to obtain zirconium dioxide precursor sol.

[0089] S5. When the zirconium dioxide precursor sol in S4 is stirred until it becomes viscous, add the silicon / carbon composite material prepared in S3. After processing with a high-speed disperser, a uniformly dispersed silicon / carbon / zirconium dioxide composite precursor is obtained.

[0090] S6. The silicon / carbon / zirconium dioxide composite precursor obtained in S5 is placed in a drying oven and stored at 70°C for 9 hours. Then, it is calcined in an air furnace at 400°C. The calcined material is then ball-milled and sieved to obtain a powdered lithium battery anode material with a particle size of 10~40μm.

[0091] Example 6

[0092] like Figure 1 As shown, a method for preparing a lithium battery anode material includes the following steps:

[0093] S1. Take 250g of silicon powder raw material with a D50 of 2μm and place it in 300mL of anhydrous ethanol, stirring until a suspension is formed; ball mill the suspension at a speed of 2500r / min, and then sieve it to make the silicon powder particle size between 10~100nm; place the silicon powder in a vacuum drying oven and dry it at a drying temperature of 65℃;

[0094] S2. Take 800g of graphite raw material and ball mill it at a speed of 2000r / min to make the graphite particle size between 1~10μm; then add the dried silicon powder, 160g of glucose and 1300mL of anhydrous ethanol from S1, and then ball mill it at a speed of 300r / min to mix it evenly to obtain the silicon / carbon composite precursor.

[0095] S3. The silicon / carbon composite precursor obtained in S2 is placed in a high-temperature furnace, protected by argon gas, and kept at 600℃ for 7 hours. Then, it is cooled to 320℃ at a rate of 5℃ / min, and then naturally cooled to room temperature. After crushing and sieving, the silicon / carbon composite material is obtained.

[0096] S4. Mix 300 mL of 0.25 mol / L Zr(NO3)4-5H2O, 160 mL of anhydrous ethanol and 16 g of styrene-butadiene-chloropropylene copolymer and stir rapidly until the solution becomes viscous to obtain zirconium dioxide precursor sol.

[0097] S5. When the zirconium dioxide precursor sol in S4 is stirred until it becomes viscous, add the silicon / carbon composite material prepared in S3. After processing with a high-speed disperser, a uniformly dispersed silicon / carbon / zirconium dioxide composite precursor is obtained.

[0098] S6. The silicon / carbon / zirconium dioxide composite precursor obtained in S5 is placed in a drying oven and stored at 70°C for 9 hours. Then, it is calcined in an air furnace at 400°C. The calcined material is then ball-milled and sieved to obtain a powdered lithium battery anode material with a particle size of 10~40μm.

[0099] Detection and Analysis

[0100] 1) After relevant testing and analysis, the structures of the lithium battery anode materials prepared in Examples 1 to 6 are as follows: Figure 2 As shown. From Figure 2 As can be seen, zirconium dioxide has a loose and porous structure, and carbon particles are uniformly dispersed inside the pores of zirconium dioxide. Nano-silicon particles are uniformly dispersed in the inner pores of carbon particles, and the surface of carbon particles is coated with an amorphous carbon layer.

[0101] 2) The lithium battery anode materials prepared in Examples 1 to 6 and the 8% silicon / carbon composite anode were used as the active materials for lithium battery anodes. Lithium metal sheets were used as the positive electrode, lithium hexafluorophosphate was used as the electrolyte, conductive carbon black was used as the conductive agent (0.8% by mass), sodium carboxymethyl cellulose was used as the binder (3.2% by mass), and the active material accounted for 96% of the total mass of the anode material. Button lithium batteries were assembled according to the above materials and parameters for cycle performance and specific capacity testing at an ambient temperature of 25°C. Peel force testing was conducted using a universal tensile testing machine with a peel angle of 90°. Three experimental groups were prepared for each case, with a peel speed of 40-100 mm / min. The average peel force was taken. The electrochemical performance and peel force test results are shown in Table 1.

[0102] Table 1 shows the electrochemical performance and peel strength test results of each lithium battery.

[0103]

[0104] In Table 1, control group 1 represents a button lithium battery made using an 8% silicon / carbon composite negative electrode as the active material of the lithium battery negative electrode; experimental group 1 represents a button lithium battery made using the lithium battery negative electrode material obtained in Example 1 as the active material of the lithium battery negative electrode; experimental group 2 represents a button lithium battery made using the lithium battery negative electrode material obtained in Example 2 as the active material of the lithium battery negative electrode; experimental group 3 represents a button lithium battery made using the lithium battery negative electrode material obtained in Example 3 as the active material of the lithium battery negative electrode; experimental group 4 represents a button lithium battery made using the lithium battery negative electrode material obtained in Example 4 as the active material of the lithium battery negative electrode; experimental group 5 represents a button lithium battery made using the lithium battery negative electrode material obtained in Example 5 as the active material of the lithium battery negative electrode; and experimental group 6 represents a button lithium battery made using the lithium battery negative electrode material obtained in Example 6 as the active material of the lithium battery negative electrode.

[0105] from Figure 1 Analysis shows that the lithium battery anode material prepared by this invention, as the anode active material of lithium battery, effectively improves the cycle performance compared with the traditional battery anode composite material that only does silicon. At the same time, it also effectively improves the stable connection between zirconium dioxide and current collector, thereby improving the peeling force between the anode material and current collector after long-term cycling.

[0106] In summary, through multiple experiments, it has been found that the lithium battery anode material of the present invention, by embedding nano-silicon material with a theoretical lithium intercalation capacity of up to 4200 mAh / g in the inner pores of carbon particles, effectively improves the lithium storage capacity of the lithium battery anode material; the relatively soft texture of the carbon particles buffers the volume change of silicon during cycling to a certain extent, effectively solving the problem of severe volume expansion of silicon during charging; and the amorphous carbon layer coated on the surface of the carbon particles improves the interface stability of the lithium battery anode material, effectively solving the problem of continuous SEI caused by the volume change of silicon material during charging and discharging. The method addresses the issue of capacity degradation caused by the continuous cracking and regeneration of the SEI film due to silicon volume changes during charging and discharging. This is achieved by embedding carbon particles coated with an amorphous carbon layer within porous zirconium dioxide, which further suppresses the volume expansion of silicon during charging. This effectively solves the problem of continuous cracking, growth, and re-cracking of the SEI film caused by silicon volume changes during charging and discharging, thus mitigating capacity decay and cycle deterioration. Furthermore, the stable connection between the zirconium dioxide layer and the current collector solves the problem of active material detaching from the current collector after long-term cycling, improving the electrode structure stability and electrochemical stability of batteries using this type of negative electrode material. The preparation method of the lithium-ion battery negative electrode material of this invention features an ingenious material structure, readily available and simple raw materials, and low operational difficulty, making it suitable for industrial production and possessing significant application value in the field of lithium-ion battery technology.

[0107] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A lithium battery anode material, characterized in that, It includes zirconium dioxide and carbon particles embedded in the pores of zirconium dioxide, wherein nano-silicon is embedded in the pores of the carbon particles, and the surface of the carbon particles is coated with an amorphous carbon layer. In the negative electrode material, by mass percentage, zirconium dioxide accounts for 5-20%, carbon particles account for 50-80%, nano-silicon accounts for 10-15%, and amorphous carbon layer accounts for 5-15%; The carbon particles have a diameter of 1~10μm, the nano-silicon particles have a diameter of 10~100nm, and the amorphous carbon layer has a thickness of ≤1μm.

2. A method for preparing the lithium battery anode material as described in claim 1, characterized in that, Includes the following steps: Silicon powder, carbon particles, amorphous carbon raw materials and dispersant are mixed and then ground to obtain a silicon / carbon composite precursor. Under an inert atmosphere, the silicon / carbon composite precursor was heat-treated at a temperature of 500~600℃, and then the temperature was lowered to room temperature and ground to obtain the silicon / carbon composite material. A dispersant and a surfactant block copolymer were added to a zirconium salt to obtain a zirconium dioxide precursor sol. The silicon / carbon composite material was dispersed in a zirconium dioxide precursor sol to obtain a silicon / carbon / zirconium dioxide composite precursor. A silicon / carbon / zirconium dioxide composite precursor is calcined to obtain a lithium battery anode material. In the anode material, by mass percentage, zirconium dioxide accounts for 5-20%, carbon particles account for 50-80%, nano-silicon accounts for 10-15%, and an amorphous carbon layer accounts for 5-15%. The particle size of the carbon particles is 1-10 μm, the particle size of the nano-silicon is 10-100 nm, and the thickness of the amorphous carbon layer is ≤1 μm.

3. The method for preparing the lithium battery anode material according to claim 2, characterized in that, The process of cooling the temperature to room temperature includes a programmed cooling to 250°C to 350°C followed by natural cooling to room temperature, wherein the programmed cooling rate is 4-10°C / min.

4. The method for preparing the lithium battery anode material according to claim 2, characterized in that, The heat treatment is a heat treatment at a temperature of 500~600℃ for 5~7 hours; The calcination temperature is 400℃~550℃.

5. The method for preparing the lithium battery anode material according to claim 2, characterized in that, The particle size of the silicon powder is between 1 and 4 μm; The zirconium salt is selected from ZrOCl2-8H2O, C 24 H 20 O 28 One or more of Zr3, C6H8O7Zr, Zr(NO3)4 and Zr(NO3)4-5H2O; The carbon particles are selected from graphite; The amorphous carbon raw material is selected from one or more of epoxy resin, phenolic resin and glucose; The dispersant is selected from one or more of ethanol, ethylene glycol, and acetone; The surfactant block copolymer is selected from polyethylene-butadiene copolymer or styrene-butadiene-chloropropylene copolymer; The inert atmosphere is selected from one or more of argon, nitrogen, and helium.

6. The method for preparing the lithium battery anode material according to claim 2, characterized in that, It also includes a drying treatment before calcination and a grinding treatment after calcination; the drying temperature is 40~60℃ and the drying time is 10~12h; the particle size of the lithium battery anode material obtained by the grinding treatment is between 10~40μm.

7. A lithium battery, characterized in that, The negative electrode active material of the lithium battery is the lithium battery negative electrode material according to claim 1.

8. A method for preparing a lithium battery as described in claim 7, characterized in that, Includes the following steps: 1) Using lithium sheets as the positive electrode; 2) Using the lithium battery negative electrode material as the negative electrode active material, negative electrode conductive agent and negative electrode binder, the mixture is mixed, homogenized, coated, rolled and sheeted to obtain a negative electrode sheet; 3) Stack the negative electrode shell, gasket, negative electrode sheet, separator, positive electrode sheet, separator, gasket, spring sheet, and positive electrode shell in that order, inject electrolyte, and complete the button cell assembly to obtain a button lithium battery.

9. The method for preparing a lithium battery according to claim 8, characterized in that, The negative electrode conductive agent is selected from one or more of conductive carbon black, graphene, carbon nanotubes, conductive graphite, and carbon fiber. The negative electrode binder is selected from one or more of sodium carboxymethyl cellulose, styrene-butadiene rubber, sodium alginate, conductive polymer polyacrylonitrile, hydroxymethyl chitosan, polyacrylic acid, and polyvinyl alcohol; The electrolyte is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, and lithium perchlorate electrolytes.

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