Silicon-carbon negative electrode material, preparation method thereof, pole piece and battery

Abstract

The invention discloses a silicon-carbon negative electrode material and a preparation method thereof, a pole piece and a battery. The preparation method of the silicon-carbon negative electrode material comprises the following steps: S1, adding a dispersing agent into a silicon-carbon precursor dispersion liquid, and then adding a precursor source to prepare a mixed solution; the precursor source at least comprises lithium dihydrogen phosphate; and S2, sequentially spraying and sintering the mixed solution to obtain the silicon-carbon negative electrode material. The silicon-carbon negative electrode material has relatively low powder resistivity, and the battery prepared from the silicon-carbon negative electrode material has excellent rate capability.

Description

Technical Field

[0001] This invention relates to a silicon-carbon anode material, its preparation method, electrode sheet, and battery. Background Technology

[0002] Currently, silicon-based anode materials are widely used due to their advantages such as high capacity, high initial efficiency, and high lithium intercalation potential. However, they still have inherent drawbacks that require further improvement. The low intrinsic conductivity of silicon and the high expansion potential of lithium intercalation remain limiting factors for the development of silicon-based materials. Therefore, solving these problems is a key step to further increase the market penetration of silicon-based materials. Currently, improving the fast-charging performance of silicon-based materials mainly focuses on three aspects: ① reducing the desolvation energy barrier; ② improving bulk diffusion; ③ improving silicon / carbon interface recombination. While some progress has been made in improving these three aspects, it is mainly based on the latter two methods. In practice, reducing the energy barrier is more conducive to improving fast-charging performance. The main problem restricting the development of this fast-charging improvement is the use of large amounts of organic matter, which is not conducive to current environmental protection initiatives. Furthermore, the complexity of the manufacturing process hinders industrial-scale production.

[0003] Therefore, there is an urgent need to provide a silicon-based anode material with high fast-charging performance to further increase its market penetration. Summary of the Invention

[0004] The technical problem this invention aims to solve is to overcome the shortcomings of poor fast-charging performance (i.e., rate performance) of silicon-based anode materials in the prior art, and to provide a silicon-carbon anode material, its preparation method, electrode sheet, and battery. This silicon-carbon anode material has a relatively low powder resistivity, and the battery made from this silicon-carbon anode material exhibits excellent rate performance.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution:

[0006] This invention provides a method for preparing a silicon-carbon anode material, comprising the following steps:

[0007] S1. Add the dispersant to the silicon-carbon precursor dispersion, and then add the precursor source to prepare a mixed solution; the precursor source includes at least lithium dihydrogen phosphate.

[0008] S2. The mixed solution is sprayed and sintered sequentially to obtain silicon-carbon anode material.

[0009] In this invention, the type of dispersant can be conventional in the art, preferably an organic dispersant, such as polyvinyl alcohol and / or polyethylene glycol.

[0010] In this invention, the dispersant is preferably added in the form of an aqueous dispersant solution. The mass percentage of the dispersant in the aqueous dispersant solution can be 0.3%-2.5%, preferably 0.5%-2.0%, for example, 1.23%, 0.74%, or 1.96%. The aqueous dispersant solution is preferably obtained by mixing the dispersant and water. The mixing temperature is preferably 40-60°C, for example, 50°C. The stirring speed is preferably 800-1200 rpm, for example, 1000 rpm. The stirring time is preferably 2-4 hours, for example, 3 hours.

[0011] In this invention, the silicon-carbon precursor can be conventional in the art, and preferably includes porous carbon and silicon particles distributed in the pores of the porous carbon.

[0012] In this invention, the D50 of the silicon-carbon precursor can be 5-10 μm, for example 6, 7, 8 or 9 μm.

[0013] In this invention, the specific surface area of ​​the silicon-carbon precursor can be 1-2 m². 2 / g, for example 1.5m 2 / g.

[0014] In this invention, the average pore size of the silicon-carbon precursor can be 1-2 nm, for example 1.8 nm.

[0015] In this invention, the tap density of the silicon-carbon precursor can be 1.2-2.2 g / cm³. 3 For example, 0.98 g / cm 3 .

[0016] In this invention, the silicon content in the silicon-carbon precursor can be 45-55%, for example 48.5%.

[0017] In this invention, the carbon content in the silicon-carbon precursor can be 45-55%, for example 51.5%.

[0018] In this invention, the solvent in the silicon-carbon precursor dispersion can be conventional in the art, such as water. The silicon-carbon precursor dispersion is preferably obtained by stirring and mixing the silicon-carbon precursor and water. The mixing temperature is preferably 40-60°C, for example, 50°C. The stirring speed is preferably 1800-2200 rpm, for example, 2000 rpm. The stirring time is preferably 1-3 hours, for example, 2 hours.

[0019] In this invention, the mass percentage of silicon-carbon precursor in the silicon-carbon precursor dispersion can be 15%-25%, preferably 17%-22%, for example 17.81%, 18.37%, 17.53%, 18.20% or 17.36%.

[0020] In this invention, the precursor source preferably further includes a lithium source and / or an aluminum source. The lithium source preferably includes lithium fluoride and / or lithium hydrogen phosphate. The aluminum source preferably includes aluminum dihydrogen phosphate.

[0021] In a preferred embodiment, the precursor source is selected from any one of the following: lithium dihydrogen phosphate, lithium fluoride and lithium dihydrogen phosphate, and aluminum dihydrogen phosphate and lithium dihydrogen phosphate.

[0022] In this invention, the precursor source is preferably added in the form of an aqueous solution of the precursor source. The mass percentage of the precursor source in the aqueous solution can be 2%-8%, for example, 4%, 3.2%, or 6.25%. The aqueous solution of the precursor source is preferably obtained by stirring and mixing the precursor source and water. The mixing temperature is preferably 40-60°C, for example, 50°C. The stirring speed is preferably 800-1200 rpm, for example, 1000 rpm. The stirring time is preferably 2-4 hours, for example, 3 hours.

[0023] In a preferred embodiment, the precursor source is selected from lithium fluoride and lithium dihydrogen phosphate, and the mass ratio of lithium fluoride to lithium dihydrogen phosphate is preferably 1:(0.5-1.5), for example 1:1.

[0024] In a preferred embodiment, the precursor source is selected from aluminum dihydrogen phosphate and lithium dihydrogen phosphate, and the mass ratio of aluminum dihydrogen phosphate to lithium dihydrogen phosphate is preferably 1:(0.5-1.5), for example 1:1.

[0025] In this invention, the mass ratio of the dispersant, the silicon-carbon precursor, and the precursor source can be 1:(8-35):(1-8), preferably 1:(10-32):(2-6), for example 1:17.3:3.3, 1:18:2.6, 1:17:5.3, 1:29.6:5.5, or 1:10.5:2.1.

[0026] In this invention, the temperature of the spray can be 180-220°C, for example 200 or 220°C.

[0027] In this invention, the spraying device can be conventional in the art, such as a peristaltic pump.

[0028] In this invention, the rotation speed during spraying can be 10-20Hz, for example 15Hz.

[0029] In this invention, a step of drying the droplets is preferably performed after spraying and before sintering. The drying temperature can be 100-140°C, for example, 120°C. The drying time can be 2-6 hours, for example, 4 hours.

[0030] The heating rate from the drying temperature to the sintering temperature is preferably 8-12°C / min, for example 10°C / min.

[0031] In this invention, the sintering temperature can be 200-600℃, for example 250, 450 or 550℃.

[0032] In this invention, the sintering time can be 8-12 hours, for example, 10 hours.

[0033] In this invention, the sintering is preferably carried out under an inert atmosphere, and more preferably under a nitrogen atmosphere.

[0034] In this invention, a silicon-carbon precursor is used as the matrix, and an aqueous solution of the precursor source is used as the precursor to regulate the energy barrier. By utilizing the dispersion effect of a dispersant, a uniformly distributed continuous particle layer is formed on the surface of the silicon-carbon precursor under a spray and sintering technical system. When the silicon-carbon anode material including this continuous particle layer is applied to a battery, it can promote the reduction of the energy barrier and accelerate the rapid transport of lithium ions during the charging and discharging process, thereby improving the rate performance of the battery.

[0035] The present invention also provides a silicon-carbon anode material, which is prepared by the preparation method described above.

[0036] The present invention also provides a silicon-carbon anode material, comprising a silicon-carbon precursor and a continuous particulate layer supported on the surface of the silicon-carbon precursor; the continuous particulate layer comprises at least lithium metaphosphate, lithium pyrophosphate and lithium phosphate.

[0037] In this invention, the continuous particle layer preferably further includes lithium-based materials and / or aluminum-based materials.

[0038] The lithium-based material preferably includes one or more of lithium metaphosphate, lithium pyrophosphate, lithium phosphate, and lithium fluoride. The aluminum-based material preferably includes one or more of aluminum metaphosphate, aluminum pyrophosphate, and aluminum phosphate.

[0039] In a preferred embodiment, the continuous particle layer comprises lithium metaphosphate, lithium pyrophosphate, and lithium phosphate.

[0040] In a preferred embodiment, the continuous particulate layer comprises lithium metaphosphate, lithium pyrophosphate, lithium phosphate, and lithium fluoride.

[0041] In a preferred embodiment, the continuous particle layer comprises lithium metaphosphate, lithium pyrophosphate, lithium phosphate, aluminum metaphosphate, aluminum pyrophosphate, and aluminum phosphate.

[0042] In this invention, the continuous particle layer is different from the coating layer. It refers to a continuous layer formed by the accumulation of particles, and the continuous layer contains particle gaps and pores.

[0043] In this invention, the D50 of the silicon-carbon anode material can be 6-10 μm, for example 7.5, 7.8, 7.6, 7.9 or 7.7 μm.

[0044] In this invention, the silicon-carbon anode material contains silicon at a mass percentage of 40%-55%, for example, 47%. The carbon mass percentage is 40%-55%, for example, 44.7%. The oxygen mass percentage is 4%-6%, for example, 5.1%.

[0045] Preferably, the mass percentage of phosphorus can be 3%-4%, for example 3.2%.

[0046] The present invention also provides an electrode comprising the silicon-carbon anode material as described above.

[0047] The present invention also provides a battery comprising the electrodes as described above.

[0048] The positive and progressive effects of this invention are as follows:

[0049] (1) The preparation method of the present invention is relatively simple and more conducive to subsequent industrialization.

[0050] (2) The silicon-carbon anode material prepared by the preparation method of the present invention has a relatively low powder resistivity, and the battery made from the silicon-carbon anode material has excellent rate performance.

[0051] Preferably, it also has excellent capacity performance, initial coulombic efficiency, and cycle performance;

[0052] Preferably, the type of precursor source can be adjusted according to actual needs, or other precursor sources can be added to form a continuous particle layer with different compositions, which can further improve the rate performance of the battery made from the obtained silicon-carbon anode material.

[0053] (3) The silicon-carbon anode material of the present invention can be applied to most batteries, including all-solid-state battery systems. Attached Figure Description

[0054] Figure 1 This is a SEM image of the silicon-carbon anode material prepared in Example 1.

[0055] Figure 2 Based on Figure 1 The element distribution diagram.

[0056] Figure 3 for Figure 1 Enlarged image. Detailed Implementation

[0057] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0058] Example 1

[0059] (1) PVA (polyvinyl alcohol, number average molecular weight of 67,000) aqueous solution was added to silicon carbon precursor dispersion, and then lithium dihydrogen phosphate (LiH2PO4) aqueous solution was added to prepare spray solution;

[0060] The method for preparing the PVA aqueous solution is as follows: 150g of PVA is added to 12000g of water (the mass percentage of PVA is 1.23%), and stirred at 1000rpm for 3h at 50℃.

[0061] The preparation method of the silicon-carbon precursor dispersion is as follows: 2600g of silicon-carbon precursor is added to 12000g of water (the mass percentage of silicon-carbon precursor is 17.8%), and stirred at 2000rpm for 2h at 50℃; the silicon-carbon precursor consists of porous carbon and silicon particles distributed in the pores of the porous carbon, with a D50 of 8μm and a specific surface area of ​​1.5 m². 2 / g, average pore size 1.8nm, tap density 0.98g / cm³ 3 The silicon content is 48.5% and the carbon content is 51.5%.

[0062] The preparation method of lithium dihydrogen phosphate aqueous solution is as follows: 500g of lithium dihydrogen phosphate is added to 12000g of water (the mass percentage of lithium dihydrogen phosphate is 4%), and stirred at 1000rpm for 3h at 50℃.

[0063] (2) Spray the spray solution obtained in step (1) at 200°C. The peristaltic pump rotates at 15 Hz during spraying. After spraying, collect the material and dry it at 120°C for 4 hours. Then, heat it to 450°C at a heating rate of 10°C / min and statically sinter it under an inert atmosphere for 10 hours to obtain silicon-carbon anode material.

[0064] Example 2

[0065] The only difference from Example 1 is that in step (1), the mass of lithium dihydrogen phosphate is 400g and the mass of silicon-carbon precursor is 2700g.

[0066] Example 3

[0067] The only difference from Example 1 is that in step (1), the mass of lithium dihydrogen phosphate is 800g and the mass of silicon-carbon precursor is 2550g.

[0068] Example 4

[0069] The only difference from Example 1 is that the mass of PVA in step (1) is 90g and the mass of silicon carbide precursor is 2670g.

[0070] Example 5

[0071] The only difference from Example 1 is that the mass of PVA in step (1) is 240g and the mass of silicon carbide precursor is 2520g.

[0072] Example 6

[0073] The only difference from Example 1 is that in step (1), lithium dihydrogen phosphate is replaced with 250g of lithium fluoride (LiF) and 250g of lithium dihydrogen phosphate.

[0074] Example 7

[0075] The only difference from Example 1 is that in step (1), lithium dihydrogen phosphate is replaced with 250g aluminum dihydrogen phosphate (Al(H2PO4)3) and 250g lithium dihydrogen phosphate.

[0076] Example 8

[0077] The only difference from Example 1 is that the sintering temperature in step (2) is 550°C.

[0078] Example 9

[0079] The only difference from Example 1 is that the sintering temperature in step (2) is 250°C.

[0080] Example 10

[0081] The only difference from Example 6 is that the sintering temperature in step (2) is 550°C.

[0082] Example 11

[0083] The only difference from Example 6 is that the sintering temperature in step (2) is 250°C.

[0084] Example 12

[0085] The only difference from Example 7 is that the sintering temperature in step (2) is 550°C.

[0086] Example 13

[0087] The only difference from Example 7 is that the sintering temperature in step (2) is 250°C.

[0088] Comparative Example 1

[0089] (1) PVA (polyvinyl alcohol, number average molecular weight of 67,000) aqueous solution was added to silicon carbon precursor dispersion, and then lithium dihydrogen phosphate (LiH2PO4) aqueous solution was added to prepare a mixed solution;

[0090] The method for preparing the PVA aqueous solution is as follows: 150g of PVA is added to 12000g of water (the mass percentage of PVA is 1.23%), and stirred at 1000rpm for 3h at 50℃.

[0091] The preparation method of the silicon-carbon precursor dispersion is as follows: 2600g of silicon-carbon precursor was added to 12000g of water (the mass percentage of silicon-carbon precursor was 17.8%), and stirred at 2000rpm for 2h at 50℃; the silicon-carbon precursor had a D50 of 8μm and a specific surface area of ​​1.5 m². 2 / g, average pore size 1.8nm, tap density 0.98g / cm³ 3 The silicon content is 48.5% by mass, and the carbon content is 51.5% by mass.

[0092] The preparation method of lithium dihydrogen phosphate aqueous solution is as follows: 500g of lithium dihydrogen phosphate is added to 12000g of water (the mass percentage of lithium dihydrogen phosphate is 4%), and stirred at 1000rpm for 3h at 50℃.

[0093] (2) The mixed solution obtained in step (1) is stirred and dried at 120°C for 8 hours. The dried material is crushed and transferred to a static sintering furnace. The temperature is raised to 450°C at a heating rate of 10°C / min. The material is statically sintered in an inert atmosphere for 10 hours to obtain silicon-carbon anode material.

[0094] In this comparative example, the spraying method was not used, and the resulting silicon-carbon anode material had severe agglomeration of lithium metaphosphate, lithium pyrophosphate, and lithium phosphate on its surface, making it impossible to form a continuous particle layer.

[0095] Comparative Example 2

[0096] The only difference from Example 1 is that lithium dihydrogen phosphate in step (1) is replaced with lithium aluminate (LiAlO2).

[0097] The continuous particulate layer of the silicon-carbon anode material prepared in this comparative example is composed of lithium aluminate.

[0098] Comparative Example 3

[0099] The only difference from Example 1 is that the lithium dihydrogen phosphate in step (1) is replaced with 250g of lithium fluoride (LiF) and 250g of aluminum dihydrogen phosphate (Al(H2PO4)3).

[0100] The continuous particle layer of the silicon-carbon anode material prepared in this comparative example consists of lithium fluoride, aluminum metaphosphate, and aluminum pyrophosphate.

[0101] Comparative Example 4

[0102] (1) PVA (polyvinyl alcohol, number average molecular weight of 67,000) aqueous solution was added to silicon carbide precursor dispersion to prepare spray solution;

[0103] The method for preparing the PVA aqueous solution is as follows: 150g of PVA is added to 12000g of water (the mass percentage of PVA is 1.23%), and stirred at 1000rpm for 3h at 50℃.

[0104] The preparation method of the silicon-carbon precursor dispersion is as follows: 3000g of silicon-carbon precursor is added to 12000g of water (the mass percentage of silicon-carbon precursor is 17.8%), and stirred at 2000rpm for 2h at 50℃; the silicon-carbon precursor has a D50 of 8μm and a specific surface area of ​​1.5 m². 2 / g, average pore size 1.8nm, tap density 0.98g / cm³ 3 The silicon content is 48.5% by mass, and the carbon content is 51.5% by mass.

[0105] (2) Spray the spray solution obtained in step (1) at 200°C. The peristaltic pump rotates at 15 Hz during spraying. After spraying, collect the material and dry it at 120°C for 4 hours. Then, heat it to 450°C at a heating rate of 10°C / min and statically sinter it under an inert atmosphere for 10 hours to obtain silicon-carbon anode material.

[0106] Example 1

[0107] (1) D50 particle size test

[0108] The D50 median particle size of the silicon-carbon anode materials prepared in the examples and comparative examples was tested using an MS3000 laser particle size analyzer. The testing standard was GB / T 24533-2019.

[0109] (2) Testing of powder resistivity

[0110] The silicon-carbon anode materials prepared in the examples and comparative examples were subjected to powder resistivity testing. The testing standard was GB / T 24525-2009.

[0111] The test results are shown in Table 1.

[0112] Table 1

[0113]

[0114] (3) Microscopic morphological observation

[0115] The silicon-carbon anode material prepared in Example 1 was photographed using a Phenom XL scanning electron microscope. The test conditions were: EHT=1kV; Signal A=InLens; WD=5.5mm; Mag=5000X.

[0116] in, Figure 1 Here is a SEM image of the silicon-carbon anode material prepared in Example 1. Figure 1 It can be seen that the silicon-carbon anode material is not agglomerated and is uniformly dispersed.

[0117] Figure 2 Based on Figure 1 Element distribution map, Figure 2 Part a is a distribution map of phosphorus. Figure 2 Part b is a distribution diagram of carbon. Figure 2 Part c is a distribution diagram of oxygen. Figure 2 The d-part is a distribution map of silicon, derived from... Figure 2 It can be seen that the elements are evenly distributed.

[0118] Figure 3 for Figure 1 Enlarged image, by Figure 3 It can be seen that composite particles (i.e., the small white particles in the figure) are indeed uniformly dispersed on the surface of the silicon-carbon anode material.

[0119] Example 2

[0120] 1. Battery manufacturing

[0121] Negative electrode sheet: First, accurately weigh the silicon-carbon negative electrode material, Super P conductive additive, and PAA binder prepared in the examples and comparative examples according to a mass ratio of 85:7:8. Place these materials in a deionized water solvent and stir thoroughly for 4 hours using a magnetic stirrer to ensure uniform mixing and form a uniform slurry. Use a transfer coating machine to uniformly coat the prepared slurry onto the Cu current collector. Place the coated current collector in a constant temperature environment of 100°C to dry for 24 hours to ensure that the moisture in the slurry is completely evaporated and to enhance the stability of the electrode. Cut the dried electrode into circular electrode sheets with a diameter of 16 mm to serve as negative electrode sheets.

[0122] lithium tablets;

[0123] Diaphragm: Polypropylene membrane is used as the diaphragm;

[0124] Electrolyte: LiPF6 was dissolved in a mixed solvent of EC and DEC (mass ratio of EC to DEC was 1:1) as the electrolyte.

[0125] In an argon-filled glove box, lithium sheets, separators, negative electrodes, and electrolytes are assembled to obtain a coin cell (model CR2430).

[0126] 2. Electrical performance testing

[0127] Test conditions: The assembled button cells were left to stand at room temperature for 12 hours to ensure that the internal components of the cells were in full contact and reached a stable state. The cycle performance and rate performance of the cells were tested using the Newway BTSDA battery testing system.

[0128] (1) Capacity performance

[0129] At 25°C, the button cells assembled by the above method were charged and discharged in a current density of 1C and a voltage range of 0.005-1.5 V. The first discharge capacity and the first charge capacity were recorded and calculated using the following formula. The test results are recorded in Table 1.

[0130] (2) Cyclic performance

[0131] At 25°C, the button cells assembled by the above method were subjected to charge-discharge tests at a current density of 1C and a voltage range of 0.005-1.5V for 100 cycles. The initial discharge capacity and the discharge capacity after 100 cycles were recorded. The test results were calculated using the following formula and recorded in Table 1.

[0132] Capacity retention rate after 100 cycles = (Discharge capacity after 100 cycles / Discharge capacity after the first cycle) × 100%

[0133] (3) Ratio performance

[0134] At 25°C, within a voltage range of 0.005–1.5 V (vs Li / Li + The discharge specific capacity of the coin cells assembled by the above method was tested at 4C.

[0135] The results data are recorded in Table 2.

[0136] Table 2

[0137]

[0138] Compared to Example 1, Comparative Example 1 did not use a spraying method, resulting in more severe agglomeration of the coating layer of the obtained silicon-carbon anode material, leading to poor rate performance. Comparative Example 2 did not include a phosphorus source as the fast-ion conductor precursor source, resulting in poor rate performance of the obtained silicon-carbon anode material. Comparative Example 3 did not include lithium dihydrogen phosphate as the fast-ion conductor precursor source, resulting in poor rate performance of the obtained silicon-carbon anode material. Comparative Example 4 did not add a precursor source, resulting in poor rate performance of the obtained silicon-carbon anode material.

[0139] A comparison of Examples 1, 6, and 7 shows that when half of the lithium dihydrogen phosphate is replaced with lithium fluoride and aluminum dihydrogen phosphate, the capacity performance, initial coulombic efficiency, rate performance, and cycle performance of the battery made from the silicon-carbon anode material are slightly reduced.

[0140] Comparisons between Examples 1 and 8, Examples 6 and 10, and Examples 7 and 12 show that when the sintering temperature is increased, the capacity performance, initial coulombic efficiency, and rate performance of the battery made from the silicon-carbon anode material decrease slightly, while the cycle performance increases slightly.

[0141] A comparison of Examples 1 and 9 shows that when the sintering temperature is reduced, the capacity performance, initial coulombic efficiency, and rate performance of the battery made from the silicon-carbon anode material decrease, while the cycle performance improves.

[0142] A comparison of Examples 6 and 11 shows that when the sintering temperature is reduced, the capacity performance, initial coulombic efficiency, and cycle performance of the battery made from the silicon-carbon anode material decrease, while the rate performance increases.

[0143] A comparison of Examples 7 and 13 shows that when the sintering temperature is reduced, the capacity performance, initial coulombic efficiency, and cycle performance of the battery made from the silicon-carbon anode material decrease, while the rate performance increases.

[0144] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for preparing a silicon-carbon anode material, characterized in that, It includes the following steps: S1. Add the dispersant to the silicon-carbon precursor dispersion, and then add the precursor source to prepare a mixed solution; the precursor source includes at least lithium dihydrogen phosphate. S2. The mixed solution is sprayed and sintered sequentially to obtain silicon-carbon anode material.

2. The method for preparing the silicon-carbon anode material as described in claim 1, characterized in that, The preparation method of the silicon-carbon anode material satisfies (1) and / or (2) of the following conditions: (1) The dispersant is an organic dispersant, such as polyvinyl alcohol and / or polyethylene glycol; The number-average molecular weight of the polyvinyl alcohol is preferably 50,000-80,000, for example 67,000; (2) The dispersant is added in the form of an aqueous dispersant solution; the mass percentage of the dispersant in the aqueous dispersant solution is preferably 0.3%-2.5%, more preferably 0.5%-2.0%, for example 1.23%, 0.74% or 1.96%.

3. The method for preparing the silicon-carbon anode material as described in claim 1, characterized in that, The preparation method of the silicon-carbon anode material satisfies one or more of the following conditions: (1) The silicon-carbon precursor comprises porous carbon and silicon particles distributed in the pores of the porous carbon; (2) The D50 of the silicon carbide precursor is 5-10 μm, for example 6, 7, 8 or 9 μm; (3) The specific surface area of ​​the silicon-carbon precursor is 1-2 m². 2 / g, for example 1.5m 2 / g; (4) The average pore size of the silicon-carbon precursor is 1-2 nm, for example 1.8 nm; (5) The tap density of the silicon-carbon precursor is 1.2-2.2 g / cm³. 3 For example, 0.98 g / cm 3 ; (6) In the silicon-carbon precursor, the mass content of silicon is 45-55%, for example 48.5%; (7) In the silicon-carbon precursor, the carbon content is 45-55% by mass, for example 51.5%; and, (8) The mass percentage of silicon carbide precursor in the silicon carbide precursor dispersion is 15%-25%, preferably 17%-22%, for example 17.81%, 18.37%, 17.53%, 18.20% or 17.36%.

4. The method for preparing the silicon-carbon anode material as described in claim 1, characterized in that, The preparation method of the silicon-carbon anode material satisfies one or more of the following conditions: (1) The precursor source further includes a lithium source and / or an aluminum source; The lithium source preferably includes lithium fluoride and / or lithium hydrogen phosphate; the aluminum source preferably includes aluminum dihydrogen phosphate. (2) The precursor source is added in the form of an aqueous solution of the precursor source; the mass percentage of the precursor source in the aqueous solution of the precursor source is preferably 2%-8%, for example 4%, 3.2% or 6.25%; and, (3) The mass ratio of the dispersant, the silicon carbide precursor and the precursor source is 1:(8-35):(1-8), preferably 1:(10-32):(2-6), for example 1:17.3:3.3, 1:18:2.6, 1:17:5.3, 1:29.6:5.5 or 1:10.5:2.

1.

5. The method for preparing the silicon-carbon anode material as described in claim 1, characterized in that, The preparation method of the silicon-carbon anode material satisfies one or more of the following conditions: (1) The temperature of the spray is 180-220°C, for example 200 or 220°C; (2) The spraying speed is 10-20Hz, for example 15Hz; (3) After spraying and before sintering, a step of drying the sprayed droplets is performed; the drying temperature is preferably 100-140℃, for example 120℃; the drying time is preferably 2-6h, for example 4h; the heating rate from the drying temperature to the sintering temperature is preferably 8-12℃ / min, for example 10℃ / min; (4) The sintering temperature is 200-600℃, for example 250, 450 or 550℃; (5) The sintering time is 8-12 hours, for example, 10 hours; and, (6) The sintering is carried out under an inert atmosphere, preferably under a nitrogen atmosphere.

6. A silicon-carbon anode material, characterized in that, It is prepared using the method for preparing silicon-carbon anode materials as described in any one of claims 1-5.

7. A silicon-carbon anode material, characterized in that, It includes a silicon-carbon precursor and a continuous particulate layer supported on the surface of the silicon-carbon precursor; the continuous particulate layer includes at least lithium metaphosphate, lithium pyrophosphate and lithium phosphate.

8. The silicon-carbon anode material as described in claim 7, characterized in that, The silicon-carbon anode material satisfies (1) and / or (2) of the following conditions: (1) The continuous particle layer further includes lithium-based materials and / or aluminum-based materials; The lithium-based substances preferably include one or more of lithium metaphosphate, lithium pyrophosphate, lithium phosphate, and lithium fluoride; the aluminum-based substances preferably include one or more of aluminum metaphosphate, aluminum pyrophosphate, and aluminum phosphate. (2) The D50 of the silicon-carbon anode material is 6-10 μm, for example 7.5, 7.8, 7.6, 7.9 or 7.7 μm.

9. An electrode sheet, characterized in that, It includes the silicon-carbon anode material as described in any one of claims 6-8.

10. A battery, characterized in that, It includes the electrode as described in claim 9.

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