A phosphorus-nickel co-doped silicon-carbon negative electrode material and a preparation method thereof

Abstract

The application discloses a kind of phosphorus nickel co-doped silicon carbon negative materials and preparation method thereof, preparation method includes that phosphoric acid, polysaccharide substance, water is mixed after stirring and obtains material A;Foam nickel is immersed into material A after ball milling, freeze-drying is sealed after vacuum, heat preservation is heated, and material B is obtained after cooling;Material B is carried out chemical vapor deposition in the mixed atmosphere of silicon source gas and inert gas, and material C is obtained after cooling;Material C, metal oxide, organic solvent are mixed after stirring and reaction, solid-liquid separation is carried out, and the obtained solid is calcined to obtain material D;Material D is placed in the mixed atmosphere of carbon source gas and inert gas and is sintered, and the phosphorus nickel co-doped silicon carbon negative material is obtained after cooling.The silicon carbon negative material prepared by the application can effectively improve the first coulomb efficiency and cycle life of the battery, and the process is simple, safe and high, which is conducive to the popularization and application of silicon carbon negative material.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a phosphorus-nickel co-doped silicon-carbon negative electrode material and a preparation method thereof. Background Art

[0002] As the excessive use of fossil energy causes air pollution and global warming, the demand for clean energy in various countries to achieve carbon neutrality goals is growing. Compared with traditional energy storage systems, advanced lithium-ion batteries (LIBs) have become one of the most important alternative technologies for energy storage. However, traditional graphite anodes have low theoretical capacity (372 mAh g -1 ), cannot meet the requirements of high energy density and high power density. Silicon anode has high theoretical lithium insertion capacity (Li 3.75 Si is 3579 mAh g -1 ), low operating voltage (<0.4V vs.Li / Li + ), abundant resources and environmental friendliness, has gradually entered the application market. However, silicon materials are in the lithium-intercalated state (Li 3.75 Si) will produce a huge volume expansion (>300%), leading to the formation of an unstable solid electrolyte interphase (SEI), particle crushing, and ultimately severe capacity decay during battery cycling. In addition, the inherent low conductivity of silicon materials (~10-3S cm -1 ) and slow lithium ion diffusion kinetics (~10-12 cm 2 s -1 ) also hinders large-scale commercial applications.

[0003] At present, in terms of commercial applications, the first coulombic efficiency can be improved to a certain extent mainly through pre-lithiation of silicon dioxide materials, including direct addition of lithium powder, electrochemical pre-embedding of lithium, etc. However, the above modification methods still have many problems. At present, the pre-lithiation process has problems such as high cost, complex process, and easy explosion during the pre-lithiation process, so it is difficult to apply in actual production. The new silicon-carbon material process is simple and low in cost. Therefore, the design and development of a new silicon-carbon material that can not only improve the first coulombic efficiency but also maintain electrode stability and improve cycle life is a key technology for realizing the practical application of silicon-based negative electrode materials.

[0004] The Chinese patent application document with publication number CN116895747A discloses a phosphorus-doped silicon-carbon composite material, its preparation method, and a secondary battery. The preparation method of the phosphorus-doped silicon-carbon composite material comprises the steps of (I): placing a carbon skeleton with a pore structure in a vapor deposition reactor, introducing a protective gas, maintaining a stirring state and heating, introducing a gaseous phosphorus source and a gaseous silicon source into the vapor deposition reactor and performing a vapor deposition reaction with the carbon skeleton to obtain composite particles. Step (II): carbon-coating the composite particles. The phosphorus-doped silicon-carbon composite material of the present invention has excellent electrochemical properties, and can alleviate the volume expansion of silicon and reduce stress damage to the material and electrode structure. However, the pore size distribution of the carbon skeleton is uneven, resulting in uneven deposition of the silicon source gas. The conductivity and volume expansion of the obtained material need to be improved, and the first coulomb efficiency and cycle life of the material are still not very ideal. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to improve the first coulombic efficiency and cycle life of silicon-carbon materials.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] A method for preparing a phosphorus-nickel co-doped silicon-carbon negative electrode material comprises the following steps:

[0008] S1. Phosphoric acid, polysaccharide and water are mixed and stirred to obtain material A;

[0009] S2, immersing nickel foam into material A and then ball milling, freeze-drying, vacuum sealing, heat preservation, and cooling to obtain material B;

[0010] S3, subjecting material B to chemical vapor deposition in a mixed atmosphere of silicon source gas and inert gas, and obtaining material C after cooling;

[0011] S4, mixing material C, a metal oxide, and an organic solvent, stirring and reacting the mixture, and calcining the obtained solid after solid-liquid separation to obtain material D;

[0012] S5. Place the material D in a mixed atmosphere of a carbon source gas and an inert gas for sintering, and obtain the phosphorus-nickel co-doped silicon-carbon negative electrode material after cooling.

[0013] Preferably, in S1, the phosphoric acid is phosphoric acid with a concentration of 1 mol / L; the mass ratio of the phosphoric acid to the polysaccharide is 1:5-10; the mass ratio of the polysaccharide to water is 5-10:55-70; the mass ratio of the total mass of the phosphoric acid and the polysaccharide contained in 1 mol / L of phosphoric acid to water is 1:2-20; and the polysaccharide is a mixture of one or more of starch, guar gum, alginate, xanthan gum and chitosan.

[0014] Preferably, in S1, the stirring time is 2h; in S2, the ball milling time is 5-12h; the freeze-drying temperature is-30℃ to-50℃, and the time is 12-24h.

[0015] Preferably, in S2, the mass ratio of the material A to the foamed nickel is 40-60:0.5-1.

[0016] Preferably, in S2, the temperature of the heat preservation and heating is 800-1000℃, and the time is 8-12h.

[0017] Preferably, in the present application, the inert atmosphere refers to a non-reactive gas atmosphere, and the inert gas refers to a non-reactive gas.

[0018] Preferably, in S3, in the mixed atmosphere of the silicon source gas and the inert gas, the volume ratio of the inert gas to the silicon source gas is 4:1 to 1:1; the inert gas is a mixture of one or more of helium, argon, and nitrogen; the silicon source gas is silane; and the silane is at least one of monosilane and disilane.

[0019] Preferably, in S3, the temperature of the chemical vapor deposition is 500-700℃, and the time is 1-6h.

[0020] Preferably, in S4, the metal oxide is a mixture of one or more of aluminum oxide, titanium dioxide, tin oxide, nickel oxide, and copper oxide; the organic solvent is a mixture of one or more of ethanol, diethyl ether, dichloromethane, acetone, and dimethylbenzene; the weight ratio of the metal oxide to the material C is 1:20-100; the weight ratio of the organic solvent to the total weight of the material C and the metal oxide is 1-4:1; the stirring reaction time is 10-30min; the calcination temperature is 300-400℃, and the time is 2-4h; and in S5, the sintering includes first-stage sintering and second-stage sintering, the first-stage sintering temperature is 300-400℃, and the time is 1-3h, and the second-stage sintering temperature is 600-800℃, and the time is 4-12h.

[0021] Preferably, in S3, after cooling, the material C is obtained by grinding to D50 of 5-8μm.

[0022] Preferably, in S2, the foamed nickel has a nickel content of ≥99.9%, and a thickness of 0.5-40mm.

[0023] Preferably, in S2, the ball-to-material mass ratio during the ball milling is 5:1 to 10:1.

[0024] Preferably, in S3, during the chemical vapor deposition, the silicon source gas flow rate is 1-5L / h, and the inert gas flow rate is 4-5L / h.

[0025] Preferably, in S3, the chemical vapor deposition is performed in a rotary furnace, and the rotation speed of the rotary furnace is 0.25 r / min to 1 r / min.

[0026] The present invention also provides a phosphorus-nickel co-doped silicon-carbon negative electrode material, which is prepared using the above-mentioned method for preparing the phosphorus-nickel co-doped silicon-carbon negative electrode material.

[0027] The present invention also provides a lithium ion battery negative electrode material, which contains the phosphorus-nickel co-doped silicon-carbon negative electrode material and graphite.

[0028] Preferably, the mass ratio of the phosphorus-nickel co-doped silicon-carbon negative electrode material to graphite is 1:9.

[0029] The advantages of the present invention are:

[0030] The method of the present invention comprises the following steps: firstly mixing phosphoric acid with a polysaccharide substance, acidifying the mixture to form a phosphorus-containing gel, then placing uniformly porous nickel foam into the gel for ball milling, wherein the phosphorus source is coated in the liquid phase so as to be uniformly distributed on the surface of the nickel substrate, which is conducive to the deposition of silicon source gas, and then freeze-drying the mixture and transferring the mixture to a tubular furnace for calcination to form a porous carbon material rich in phosphorus and nickel. The introduction of the phosphorus source improves the electrical conductivity of the material, the nickel foam provides a porous structure, and freeze-drying further forms pores. At the same time, the nickel element provides an adsorption site for silane deposition, which can uniformly deposit the silicon source gas, and then chemical vapor deposition is used to introduce a silicon source into the phosphorus-nickel co-doped carbon material to form a phosphorus-nickel co-doped silicon-carbon composite material, thereby improving the energy density and cycle life of the material, and then introducing a metal oxide onto the surface of the phosphorus-doped silicon-carbon composite material to further improve the capacity and conductivity of the material, and then, under the catalytic action of nickel, the carbon source gas coats a layer of carbon nanotubes on the surface of the material to form a conductive network to improve the conductivity while further limiting the volume expansion of the material, thereby obtaining a novel silicon-carbon negative electrode material with high initial efficiency and long cycle life. The silicon-carbon negative electrode material prepared by the present invention can effectively improve the initial coulombic efficiency and cycle life of the battery, and has a simple process and high safety, which is conducive to the promotion and application of silicon-carbon negative electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the SEM test result of the silicon-carbon negative electrode material prepared in Example 1 of the present invention;

[0032] Figure 2 The charge and discharge capacity test results of the silicon-carbon negative electrode material prepared in Example 1 of the present invention and the commercial SiO / C material in Comparative Example 1;

[0033] Figure 3 These are the cycle performance test results of the silicon-carbon negative electrode material prepared in Example 1 of the present invention and the commercial SiO / C material in Comparative Example 1. DETAILED DESCRIPTION

[0034] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0035] The test materials and reagents used in the following examples, and the like, can be obtained from commercial channels unless otherwise specified.

[0036] If a specific technique or condition is not specified in the examples, it can be performed according to the technique or condition described in the literature in the art or according to the product manual.

[0037] Example 1

[0038] A preparation method of a phosphorus-nickel co-doped silicon-carbon negative electrode material, comprising the following steps:

[0039] S1, 10g of 1mol / L phosphoric acid and 50g of starch were mixed in a beaker, then 600g of deionized water was added, and stirred for 2h to obtain material A;

[0040] S2, 50g of material A was taken, 1g of foam nickel with a thickness of 40mm was immersed, 250g of ball milling beads was added, and ball milling was performed for 10h, then it was transferred to a freeze dryer, -30℃ freeze drying was performed for 12h, then it was taken out and placed in a tube furnace, vacuum sealing was performed, then 900℃ heat preservation was performed for 10h, and after cooling, grinding was performed to obtain material B;

[0041] S3, 20g of material B was placed in a rotary furnace, silane gas and argon gas were introduced, the flow rate of the silane gas was 5L / h, the flow rate of the argon gas was 5L / h, chemical vapor deposition was performed at 500℃ for 2h under the condition that the rotation speed of the furnace body was 1r / min, then it was cooled to room temperature, then it was placed in a mechanical mill and ground to D50 of 5μm to obtain material C;

[0042] S4, 20g of material C and 0.2g of alumina were placed in 40g of anhydrous ethanol, stirring reaction was performed for 30min, then suction filtration was performed, the filter cake was placed in a crucible and transferred to an argon atmosphere tube furnace, calcination was performed at 400℃ for 2h to obtain material D;

[0043] S5, material D was placed in a tube furnace, a mixed gas of acetylene and argon with a volume ratio of 1:1 was introduced, first sintering was performed at 400℃ for 2h, then sintering was performed at 600℃ for 12h, and after cooling, the phosphorus-nickel co-doped silicon-carbon negative electrode material was obtained.

[0044] Example 2

[0045] A method for preparing a phosphorus-nickel co-doped silicon-carbon negative electrode material comprises the following steps:

[0046] S1. Mix 10 g of 1 mol / L phosphoric acid and 100 g of starch in a beaker, then add 550 g of deionized water and stir for 2 h to obtain material A;

[0047] S2. Take 50 g of material A, immerse 0.5 g of nickel foam with a thickness of 30 mm into it, add 250 g of ball milling beads, ball mill for 8 h, transfer to a freeze dryer, freeze-dry at -40°C for 12 h, take out and place in a tube furnace, vacuum seal and keep at 900°C for 10 h, cool and grind to obtain material B;

[0048] S3. 20 g of material B was placed in a rotary furnace, and monosilane gas and argon gas were introduced at a monosilane gas flow rate of 1 L / h and an argon gas flow rate of 4 L / h. Chemical vapor deposition was performed at 600° C. for 2 h at a furnace speed of 1 r / min. The product was cooled to room temperature and then ground in a mechanical mill until D50 was 5 μm to obtain material C.

[0049] S4, 20 g of material C and 0.2 g of titanium dioxide were placed in 40 g of acetone, stirred and reacted for 30 min, then filtered, and the filter cake was placed in a crucible and transferred to an argon atmosphere tube furnace and calcined at 400 ° C for 2 h to obtain material D;

[0050] S5. Place material D in a tube furnace, introduce a mixed gas of acetylene and argon (volume ratio 1:1), first heat and sinter at 400°C for 2 hours, then heat and sinter at 800°C for 12 hours, and after cooling, obtain the phosphorus-nickel co-doped silicon-carbon negative electrode material.

[0051] Example 3

[0052] A method for preparing a phosphorus-nickel co-doped silicon-carbon negative electrode material comprises the following steps:

[0053] S1. Mix 10 g of 1 mol / L phosphoric acid and 60 g of starch in a beaker, then add 700 g of deionized water and stir for 2 h to obtain material A;

[0054] S2. Take 40 g of material A, immerse 1 g of nickel foam with a thickness of 40 mm into it, add 400 g of ball milling beads, ball mill for 10 h, transfer to a freeze dryer, freeze-dry at -40°C for 15 h, take out and place in a tube furnace, vacuum seal and keep at 800°C for 12 h, cool and grind to obtain material B;

[0055] S3, 20g of the material B was placed in a rotary furnace, silane gas and argon gas were introduced, the flow rate of the silane gas was 2L / h, the flow rate of the argon gas was 4L / h, chemical vapor deposition was carried out at 600 DEG C for 2h under the condition that the rotation speed of the furnace body was 1r / min, then it was cooled to room temperature, and then it was placed in a mechanical mill to be ground to D50 of 5um, and material C was obtained;

[0056] S4, 20g of the material C and 1g of tin oxide were placed in 80g of anhydrous ethanol, stirred for 30min, then suction filtration was performed, the filter cake was placed in a crucible and transferred to a tube furnace in an argon atmosphere, and calcination was performed at 300 DEG C for 2h, and material D was obtained;

[0057] S5, the material D was placed in a tube furnace, a mixed gas of acetylene and argon (volume ratio 1:1) was introduced, first sintered at 300 DEG C for 2h, and then sintered at 700 DEG C for 12h, and the phosphorus-nickel co-doped silicon-carbon negative electrode material was obtained after cooling.

[0058] Example 4

[0059] A preparation method of a phosphorus-nickel co-doped silicon-carbon negative electrode material, comprising the following steps:

[0060] S1, 10g of 1mol / L phosphoric acid was mixed with 50g of starch in a beaker, then 600g of deionized water was added, and stirred for 2h to obtain material A;

[0061] S2, 60g of the material A was taken, 1g of foam nickel with a thickness of 30mm was immersed, 480g of ball milling beads was added, and after ball milling for 12h, it was transferred to a freeze dryer, freeze dried at-30 DEG C for 24h, then placed in a tube furnace, vacuum sealed, and calcined at 1000 DEG C for 12h, and then ground after cooling to obtain material B;

[0062] S3, 20g of the material B was placed in a rotary furnace, silane gas and argon gas were introduced, the flow rate of the silane gas was 5L / h, the flow rate of the argon gas was 5L / h, chemical vapor deposition was carried out at 500 DEG C for 2h under the condition that the rotation speed of the furnace body was 1r / min, then it was cooled to room temperature, and then it was placed in a mechanical mill to be ground to D50 of 5um, and material C was obtained;

[0063] S4, 20g of the material C and 0.2g of aluminum oxide were placed in 40g of anhydrous ethanol, stirred for 30min, then suction filtration was performed, the filter cake was placed in a crucible and transferred to a tube furnace in an argon atmosphere, and calcination was performed at 400 DEG C for 2h, and material D was obtained;

[0064] S5, the material D was placed in a tube furnace, a mixed gas of acetylene and argon (volume ratio 1:1) was introduced, first sintered at 400 DEG C for 2h, and then sintered at 600 DEG C for 12h, and the phosphorus-nickel co-doped silicon-carbon negative electrode material was obtained after cooling.

[0065] Comparative Example 1

[0066] Comparative Example 1 is a commercial SiO / C material.

[0067] Comparative Example 2

[0068] A method for preparing a silicon-carbon negative electrode material comprises the following steps:

[0069] S1. Mix 10 g of 1 mol / L phosphoric acid and 50 g of starch in a beaker, then add 600 g of deionized water and stir for 2 h to obtain material A;

[0070] S2. Take 50 g of material A and put it into a freeze dryer, freeze-dry it at -30°C for 12 hours, take it out and put it into a tube furnace, seal it under vacuum and keep it at 900°C for 10 hours, cool it and grind it to obtain material B;

[0071] S3, 20g of material B was placed in a rotary furnace, and monosilane gas and argon gas were introduced, with the monosilane gas flow rate being 5L / h and the argon gas flow rate being 5L / h. Chemical vapor deposition was performed at 500°C for 2h at a furnace speed of 1r / min. The product was cooled to room temperature and then ground in a mechanical mill until D50 was 5μm to obtain material C;

[0072] S4. Place 20 g of material C and 0.2 g of aluminum oxide in 40 g of anhydrous ethanol, stir and react for 30 min, then filter with suction, place the filter cake in a crucible and transfer it to an argon atmosphere tube furnace and calcine at 400° C. for 2 h to obtain material D;

[0073] S5. Place material D in a tubular furnace, introduce a mixed gas of acetylene and argon (volume ratio 1:1), heat and sinter at 400°C for 2 hours, then heat and sinter at 600°C for 12 hours, and obtain the product after cooling.

[0074] Comparative Example 3

[0075] A method for preparing a silicon-carbon negative electrode material comprises the following steps:

[0076] S1. Mix 10 g of 1 mol / L phosphoric acid and 50 g of starch in a beaker, then add 600 g of deionized water and stir for 2 h to obtain material A;

[0077] S2. Take 50 g of material A, immerse 1 g of nickel foam with a thickness of 40 mm into it, add 250 g of ball milling beads, ball mill for 10 h, transfer to a freeze dryer, freeze-dry at -30°C for 12 h, take out and place in a tube furnace, vacuum seal and keep at 900°C for 10 h, cool and grind to obtain material B;

[0078] S3, 20g of material B was placed in a rotary furnace, and monosilane gas and argon gas were introduced, with the monosilane gas flow rate being 5L / h and the argon gas flow rate being 5L / h. Chemical vapor deposition was performed at 500°C for 2h at a furnace speed of 1r / min. The product was cooled to room temperature and then ground in a mechanical mill until D50 was 5μm to obtain material C;

[0079] S4. Place material C in a tubular furnace, introduce a mixed gas of acetylene and argon (volume ratio 1:1), heat and sinter at 400°C for 2 hours, then heat and sinter at 600°C for 12 hours, and obtain the product after cooling.

[0080] Comparative Example 4

[0081] A method for preparing a silicon-carbon negative electrode material comprises the following steps:

[0082] S1. Place 50 g of starch in a beaker, then add 600 g of deionized water and stir for 2 h to obtain material A;

[0083] S2. Take 50 g of material A, immerse 1 g of nickel foam with a thickness of 40 mm into it, add 250 g of ball milling beads, ball mill for 10 h, transfer to a freeze dryer, freeze-dry at -30°C for 12 h, take out and place in a tube furnace, vacuum seal and keep at 900°C for 10 h, cool and grind to obtain material B;

[0084] S3, 20g of material B was placed in a rotary furnace, and monosilane gas and argon gas were introduced, with the monosilane gas flow rate being 5L / h and the argon gas flow rate being 5L / h. Chemical vapor deposition was performed at 500°C for 2h at a furnace speed of 1r / min. The product was cooled to room temperature and then ground in a mechanical mill until D50 was 5μm to obtain material C;

[0085] S4. Place 20 g of material C and 0.2 g of aluminum oxide in 40 g of anhydrous ethanol, stir and react for 30 min, then filter with suction, place the filter cake in a crucible and transfer it to an argon atmosphere tube furnace and calcine at 400° C. for 2 h to obtain material D;

[0086] S5. Place material D in a tubular furnace, introduce a mixed gas of acetylene and argon (volume ratio 1:1), heat and sinter at 400°C for 2 hours, then heat and sinter at 600°C for 12 hours, and obtain the product after cooling.

[0087] Test example

[0088] The negative electrode material prepared in Example 1 was subjected to SEM testing, and the results were as follows: Figure 1 As shown. Figure 1 It can be seen that the particle size of the new silicon-carbon negative electrode material prepared in Example 1 is relatively uniform, and the particle size is about 5 μm.

[0089] The negative electrode materials prepared in Examples 1-4 and Comparative Examples 2-4 and the commercial SiO / C material of Comparative Example 1 were respectively used as negative electrode active materials, and the negative electrode active material: conductive agent SP: binder LA133 were mixed and coated in a mass ratio of 8:1:1 to assemble a CR2016 button battery. The electrolyte used was a 1 mol / L LiPF6 EC+DMC (mass ratio 1:1) solution, and the electrochemical performance test was carried out. The results are shown in Tables 1 and Figure 2-3 As shown. With NCM811 as the positive electrode, 10wt% of the negative electrode material prepared in Example 1 + 90wt% of the conventional graphite mixed material and 10wt% of the material in Comparative Example 1 + 90wt% of the conventional graphite mixed material (mass ratio) as the negative electrode, slurry mixing, coating, rolling, slitting, die cutting, lamination, welding of the electrode ears, top and side sealing, baking, and liquid injection were performed to assemble a 7Ah soft pack battery. After the battery was divided into different capacities, a room temperature cycle test was performed at a current density of 1C / 1C. The test results are shown in FIG. Figure 3 shown.

[0090] Table 1

[0091] First discharge specific capacity / mAh / g First charge specific capacity / mAh / g First coulombic efficiency Example 1 2107.6 1963.5 93.2％ Example 2 2088.0 1939.7 92.9％ Example 3 2105.8 1953.2 92.8％ Example 4 2098.1 1933.4 92.2％ Comparative Example 1 2186.1 1646.3 75.3％ Comparative Example 2 2036.4 1702.4 83.6％ Comparative Example 3 2168.9 1802.1 83.1％ Comparative Example 4 2117.2 1723.1 81.4％

[0092] As shown in Table 1, the silicon-carbon material prepared in the embodiment has significantly improved charge capacity and first coulombic efficiency compared with the control example.

[0093] Depend on Figure 2 It can be seen that the capacity and first efficiency of the silicon-carbon material prepared in Example 1 are higher than those in Comparative Example 1.

[0094] Depend on Figure 3 It can be seen that the capacity retention rate of the material prepared in Example 1 after 600 cycles in the battery cell is 94%, while the capacity retention rate of the material prepared in Comparative Example 1 after 600 cycles in the battery cell is 87%.

[0095] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a phosphorus-nickel co-doped silicon-carbon negative electrode material, characterized in that: The following steps are involved: S1. Phosphoric acid, a polysaccharide, and water are mixed and stirred to obtain material A; the phosphoric acid has a concentration of 1 mol / L; the mass ratio of the phosphoric acid to the polysaccharide is 1:5-10; the mass ratio of the polysaccharide to water is 5-10:55-70; the mass ratio of the total mass of the phosphoric acid and the polysaccharide contained in 1 mol / L phosphoric acid to the water is 1:2-20; the polysaccharide is a mixture of one or more of starch, guar gum, alginate, xanthan gum, and chitosan; S2, immersing nickel foam into material A and then ball milling, freeze-drying, vacuum sealing, heat preservation, and cooling to obtain material B; S3, subjecting material B to chemical vapor deposition in a mixed atmosphere of silicon source gas and inert gas, and obtaining material C after cooling; S4, mixing material C, a metal oxide, and an organic solvent, stirring and reacting the mixture, and calcining the obtained solid after solid-liquid separation to obtain material D; S5. Place the material D in a mixed atmosphere of a carbon source gas and an inert gas for sintering, and obtain the phosphorus-nickel co-doped silicon-carbon negative electrode material after cooling.

2. The method for preparing the phosphorus-nickel co-doped silicon-carbon negative electrode material according to claim 1, characterized in that: In S1, the stirring time is 2 hours; in S2, the ball milling time is 5-12 hours; the freeze-drying temperature is -30°C to -50°C, and the time is 12-24 hours.

3. The method for preparing the phosphorus-nickel co-doped silicon-carbon negative electrode material according to claim 1, characterized in that: In S2, the mass ratio of the material A to the nickel foam is 40-60:0.5-1.

4. The method for preparing the phosphorus-nickel co-doped silicon-carbon negative electrode material according to claim 1, characterized in that: In S2, the temperature of the heat preservation heating is 800-1000°C and the time is 8-12 hours.

5. The method for preparing the phosphorus-nickel co-doped silicon-carbon negative electrode material according to claim 1, characterized in that: In S3, in the mixed atmosphere of silicon source gas and inert gas, the volume ratio of inert gas to silicon source gas is 4:1~1:1; the inert gas is a mixture of one or more of helium, argon, and nitrogen; the silicon source gas is silane; and the silane is at least one of monosilane and disilane.

6. The method for preparing the phosphorus-nickel co-doped silicon-carbon negative electrode material according to claim 1, characterized in that: In S3, the chemical vapor deposition temperature is 500-700° C., and the time is 1-6 hours.

7. The method for preparing a phosphorus-nickel co-doped silicon-carbon negative electrode material according to claim 1, characterized in that: In S4, the metal oxide is a mixture of one or more of aluminum oxide, titanium dioxide, tin oxide, nickel oxide, and copper oxide; the organic solvent is a mixture of one or more of ethanol, ether, dichloromethane, acetone, and xylene; the weight ratio of the metal oxide to material C is 1:20-100; the weight ratio of the mass of the organic solvent to the total weight of material C and the metal oxide is 1-4:1; the stirring reaction time is 10-30 minutes; the calcination temperature is 300-400°C, and the time is 2-4 hours; in S5, the sintering includes a first stage sintering and a second stage sintering, the first stage sintering temperature is 300~400°C, the time is 1~3 hours, and the second stage sintering temperature is 600~800°C, and the time is 4~12 hours.

8. A phosphorus-nickel co-doped silicon-carbon negative electrode material, characterized by: The material is prepared by the method for preparing a phosphorus-nickel co-doped silicon-carbon negative electrode material according to any one of claims 1 to 7.

9. A negative electrode material for a lithium-ion battery, characterized in that: Contains the phosphorus-nickel co-doped silicon-carbon negative electrode material as claimed in claim 8 and graphite.

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