A method for preparing a high-first-efficiency high-tapping-density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste

Abstract

The application provides a method for preparing a high-first-efficiency high-tapped-density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste, and belongs to the technical fields of secondary recycling of silicon resources and lithium ion batteries. The method comprises the following steps: firstly, removing impurities from the photovoltaic crystalline silicon waste through pretreatment; secondly, constructing a lithium silicate solid electrolyte by performing in-situ prelithiation treatment on the pretreated photovoltaic crystalline silicon waste; thirdly, obtaining high-sphericity silicon-carbon microspheres by spraying and self-assembling the prelithiated silicon material; and finally, introducing the silicon-carbon microspheres into a dense carbon skeleton through fluidized bed carbon deposition to obtain a high-sphericity silicon-carbon negative electrode material with high first coulomb efficiency and high tapped density. The application provides a new idea and a new path for the value-added recycling of photovoltaic industrial crystalline silicon waste and the construction of high-performance lithium ion batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical fields of secondary recycling of silicon resources and lithium ion battery, and particularly relates to a method for preparing high initial efficiency and high tap density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste. BACKGROUND

[0002] Currently, the negative electrode material on the market is mainly graphite material, but its low theoretical specific capacity (372 mAh.g -1 ) cannot meet the development target of lithium ion power battery single specific energy greater than 500 Wh / kg, and the next generation of battery materials needs to be developed urgently. The theoretical capacity of silicon is 4200 mAh.g -1 , which is ten times that of commercial graphite negative electrode, has the advantages of high capacity, wide source and moderate lithium intercalation potential, and is generally considered as the next generation of lithium battery negative electrode material. However, a series of problems caused by the large volume expansion, poor conductivity, low initial coulombic efficiency and low tap density of silicon negative electrode material have become the main challenges in current research and application.

[0003] In order to improve the volume expansion problem of silicon-based negative electrode, domestic and foreign researchers have focused on the nanocrystallization of silicon material, and have made a series of research progress. Studies have shown that when the size of silicon particles reaches nanoscale, the huge expansion stress generated during charging and discharging of silicon material will be dispersed into thousands of small spaces around the silicon nanoparticles, thereby improving the structural stability and cycle life of silicon negative electrode material. The ultra-thin silicon nanosheet has a very small thickness, and the longitudinal volume change is small during charging and discharging, which can prevent the cracking of silicon negative electrode caused by volume expansion during charging and discharging. However, the large specific surface area of nanosilicon will increase the contact area with electrolyte and consume a large amount of lithium ions in the battery, resulting in irreversible capacity loss. In addition, nanosilicon is usually prepared at high cost, and it is difficult to meet the requirements of commercial lithium ion battery negative electrode material such as initial coulombic efficiency, tap density, electrode area density and electrode thickness. Carbon material is low in price, good in conductivity and also a kind of lithium intercalation material with small volume expansion. The composite of carbon material and silicon not only can buffer the huge volume change of silicon during the cycle process, but also can make up for the poor conductivity of silicon. Therefore, silicon-carbon composite material is considered as the best negative electrode material candidate for commercialization of high-energy-density lithium ion battery. SUMMARY

[0004] The purpose of the present application is to provide a method for preparing high initial efficiency and high tap density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste, which solves the technical problems of high preparation cost, low initial coulombic efficiency and low tap density of lithium ion battery nanosilicon-based negative electrode material in the prior art.

[0005] In order to achieve the above-mentioned application purpose, the present application provides the following technical scheme:

[0006] The application provides a method for preparing a high-initial-efficiency high-tapping-density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste, comprising the following steps:

[0007] (1) in-situ prelithiation treatment of the photovoltaic crystalline silicon waste to obtain prelithiated silicon material;

[0008] (2) mixing of the prelithiated silicon material, carbon source, additive, pore-forming agent and solvent to obtain a precursor solution, and spray self-assembly of the precursor solution to obtain silicon-carbon microspheres;

[0009] (3) carbon deposition reaction of the silicon-carbon microspheres to obtain the high-initial-efficiency high-tapping-density silicon-carbon negative electrode material.

[0010] Further, in the step (1), the photovoltaic crystalline silicon waste is obtained after pretreatment of waste silicon slag and cutting silicon waste generated in the photovoltaic silicon production process.

[0011] Further, the pretreatment comprises acid pickling, and the acid pickling solution comprises one or more of hydrofluoric acid, hydrochloric acid, nitric acid and sulfuric acid, the concentration of the acid pickling solution is 0.1-8 mol / L, the acid pickling time is 0.1-8 h, and the liquid-solid ratio is 3-10 mL:1 g.

[0012] Further, the pretreatment further comprises ball milling or sand milling, and the particle size distribution of the photovoltaic crystalline silicon waste after ball milling or sand milling is 0.05-5 μm.

[0013] Further, in the step (1), the lithium source used for the in-situ prelithiation treatment comprises a solid-phase lithium source and / or a liquid-phase lithium source, the lithium source comprises one or more of LiCl, LiOH, Li2CO3, Li2SO4, LiNa, LiBr, LiI, LiC2H3O2, LiNO3, Li3PO4 and LiHSO4, the mass fraction of the liquid-phase lithium source is 0.1%-20%, and the addition amount of the lithium source is 0.1-10 wt% of the prelithiated silicon material.

[0014] Further, the temperature of the in-situ prelithiation treatment is 60-1000 ℃, the time of the in-situ prelithiation treatment is 0.1-20 h, and the atmosphere of the in-situ prelithiation treatment comprises one or more of air, argon and nitrogen.

[0015] Further, in the step (2), the mass ratio of the prelithiated silicon material, carbon source, additive, pore-forming agent and solvent is 1-80:1-60:0.1-5:0.1-5:10-2000.

[0016] Further, in the step (2), the carbon source includes at least two of graphite, pitch, glucose, graphene, carbon nanotube, phenolic resin and polydopamine, the solvent is one or more of deionized water, methanol, ethanol, propanol, butanol, ethylene glycol and propylene glycol, the additive includes one or more of TiO2, CuO, Ag, Fe(NO3)3 and Ni(NO3)2, and the pore-forming agent includes one or more of LiCl, Na2CO3, KCl, CaCl2, NaCl and MgCl2.

[0017] Further, in the step (2), the feeding speed of the spray self-assembly is 0.01-100 mL / min, the air inlet speed is 0.1-100 mL / min, the gas includes one or more of air, argon and nitrogen, and the temperature of the spray self-assembly is 100-300 DEG C.

[0018] Further, in the step (3), the carbon deposition precursor in the carbon deposition reaction includes active gas, hydrogen and argon, wherein the proportion of hydrogen is 10-40%, the proportion of argon is 20-50%, and the proportion of active gas is 10-60%, the active gas includes one or more of methane, ethane, propane, acetylene, propyne and carbon monoxide, and the flow rate of the carbon deposition precursor is 0.1-10 m / s.

[0019] Further, in the step (3), the temperature of the carbon deposition reaction is 400-1200 DEG C, and the time of the carbon deposition reaction is 0.1-12 h.

[0020] The beneficial effects of the present application are as follows:

[0021] The present application has the advantages of simple equipment, easy operation and easy amplification, and can not only effectively solve the problem of difficult recovery of crystalline silicon waste in the photovoltaic industry, but also effectively prepare high initial efficiency and high tap density spherical silicon-carbon negative electrode materials.

[0022] The present application ingeniously converts the harmful intrinsic silicon oxide layer on the surface of the photovoltaic crystalline silicon waste into a beneficial lithium silicate solid electrolyte protective layer, effectively improving the initial coulombic efficiency of the silicon negative electrode material.

[0023] The present application first proposes a spray granulation combined with a fluidized bed carbon deposition reaction to prepare an outer dense and inner porous spherical silicon-carbon negative electrode material, which simultaneously realizes the effects of improving the volume expansion of the silicon negative electrode, improving the conductivity and improving the tap density. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The morphology of the high initial efficiency and high tap density spherical silicon-carbon negative electrode material prepared in Example 1 is shown in the figure.

[0025] Figure 2 The morphology of the high initial efficiency and high tap density spherical silicon-carbon negative electrode material prepared in Example 2 is shown in the figure.

[0026] Figure 3 Morphology of high initial efficiency and high tap density spherical silicon-carbon negative electrode material prepared for example 3;

[0027] Figure 4 Morphology of high initial efficiency and high tap density spherical silicon-carbon negative electrode material prepared for example 4;

[0028] Figure 5 Morphology of high initial efficiency and high tap density spherical silicon-carbon negative electrode material prepared for example 5. DETAILED DESCRIPTION

[0029] The application provides a method for preparing high initial efficiency and high tap density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste, comprising the following steps:

[0030] (1) performing in-situ prelithiation treatment on the photovoltaic crystalline silicon waste to obtain prelithiated silicon material;

[0031] (2) mixing the prelithiated silicon material, carbon source, additive, pore-forming agent and solvent to obtain a precursor solution, and performing spray self-assembly on the precursor solution to obtain silicon-carbon microspheres;

[0032] (3) performing carbon deposition reaction on the silicon-carbon microspheres to obtain high initial efficiency and high tap density silicon-carbon negative electrode material.

[0033] In the application, in step (1), the photovoltaic crystalline silicon waste is obtained by pretreating waste silicon slag and cutting silicon waste generated in the photovoltaic silicon production process.

[0034] In the application, the pretreatment comprises acid pickling, and the acid pickling solution comprises one or more of hydrofluoric acid, hydrochloric acid, nitric acid and sulfuric acid, preferably hydrofluoric acid and / or hydrochloric acid; the concentration of the acid pickling solution is 0.1-8 mol / L, preferably 1-7 mol / L, and further preferably 2-6 mol / L; the acid pickling time is 0.1-8 h, preferably 1-7 h, and further preferably 2-6 h; and the liquid-solid ratio is 3-10 mL:1 g, preferably 4-9 mL:1 g, and further preferably 5-8 mL:1 g.

[0035] In the application, the pretreatment further comprises ball milling or sand milling, and the particle size distribution of the photovoltaic crystalline silicon waste after ball milling or sand milling is 0.05-5 μm, preferably 1-4 μm, and further preferably 2-3 μm.

[0036] In the present application, in the step (1), the lithium source used in the in-situ pre-lithiation treatment includes a solid-phase lithium source and / or a liquid-phase lithium source, and the lithium source contains one or more of LiCl, LiOH, Li2CO3, Li2SO4, LiNa, LiBr, LiI, LiC2H3O2, LiNO3, Li3PO4 and LiHSO4, preferably one or more of LiCl, LiOH and Li2CO3;

[0037] The mass fraction of the liquid-phase lithium source is 0.1% to 20%, preferably 1% to 10%, and further preferably 2% to 5%; and the amount of the lithium source added is 0.1 to 10 wt% of the pre-lithiated silicon material, preferably 1 to 9 wt%, and further preferably 2 to 8 wt%.

[0038] In the present application, the temperature of the in-situ pre-lithiation treatment is 60 to 1000℃, preferably 100 to 950℃, and further preferably 150 to 900℃; the time of the in-situ pre-lithiation treatment is 0.1 to 20h, preferably 1 to 19h, and further preferably 2 to 18h; and the atmosphere of the in-situ pre-lithiation treatment includes one or more of air, argon and nitrogen, preferably argon and / or nitrogen.

[0039] In the present application, in the step (2), the mass ratio of the pre-lithiated silicon material, the carbon source, the additive, the pore-forming agent and the solvent is 1 to 80: 1 to 60: 0.1 to 5: 0.1 to 5: 10 to 2000, preferably 10 to 50: 10 to 50: 1 to 4: 1 to 4: 200 to 1000, and further preferably 10 to 30: 20 to 40: 2 to 3: 2 to 3: 400 to 800.

[0040] In the present application, in the step (2), the carbon source includes at least two of graphite, pitch, glucose, graphene, carbon nanotubes, phenolic resin and polydopamine; the solvent is one or more of deionized water, methanol, ethanol, propanol, butanol, ethylene glycol and propylene glycol; the additive includes one or more of TiO2, CuO, Ag, Fe(NO3)3 and Ni(NO3)2; and the pore-forming agent includes one or more of LiCl, Na2CO3, KCl, CaCl2, NaCl and MgCl2.

[0041] In the present application, in the step (2), the feeding speed of the spray self-assembly is 0.01-100 mL / min, preferably 1-90 mL / min, and further preferably 2-80 mL / min; the gas inlet speed is 0.1-100 mL / min, preferably 2-90 mL / min, and further preferably 5-80 mL / min; the gas includes one or more of air, argon and nitrogen, and is preferably argon and / or nitrogen; the temperature of the spray self-assembly is 100-300℃, preferably 120-280℃, and further preferably 150-250℃.

[0042] In the present application, in the step (3), the carbon deposition precursor in the carbon deposition reaction includes active gas, hydrogen and argon, wherein the proportion of hydrogen is 10-40%, preferably 15-35%, and further preferably 20-30%; the proportion of argon is 20-50%, preferably 25-45%, and further preferably 30-40%; the proportion of active gas is 10-60%, preferably 20-50%, and further preferably 30-40%; the active gas includes one or more of methane, ethane, propane, acetylene, propyne and carbon monoxide, and is preferably one or more of ethane, acetylene and propyne; the flow rate of the carbon deposition precursor is 0.1-10 m / s, preferably 2-8 m / s, and further preferably 4-6 m / s.

[0043] In the present application, in the step (3), the temperature of the carbon deposition reaction is 400-1200℃, and the activity of plasma can be used to promote the progress of the carbon deposition reaction; the temperature of the carbon deposition reaction is preferably 500-1100℃, and further preferably 600-1000℃; the time of the carbon deposition reaction is 0.1-12 h, preferably 1-11 h, and further preferably 2-10 h.

[0044] In the present application, the silicon-carbon microspheres are introduced into the dense carbon skeleton by the fluidized bed carbon deposition method.

[0045] The technical solutions provided by the present application are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0046] Example 1

[0047] A method for preparing a high-first-efficiency high-tapping-density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste, and the specific steps are as follows:

[0048] (1) The cutting silicon waste of about 1 μm generated in the photovoltaic silicon production process is placed in a 1 mol / L hydrofluoric acid solution with a liquid-solid ratio of 3 mL:1 g for acid washing for 1 h to obtain pretreated silicon material; the pretreated silicon material is mixed with 2 wt% LiOH of the pre-lithiated silicon material by ball milling, and then reacted at 600℃ in an argon atmosphere for 1 h to obtain the pre-lithiated silicon material.

[0049] (2) The pre-lithiated silicon material, graphite, glucose, additive TiO2, pore-forming agent NaCl and ethanol are mixed according to a mass ratio of 20:40:5:1:1:600 to obtain a precursor solution; the precursor solution is added at a feeding speed of 1 mL / min, and nitrogen is added at an air feeding speed of 10 mL / min; the precursor solution is subjected to spray self-assembly under the condition of nitrogen protection at 100℃ to obtain silicon-carbon microspheres;

[0050] (3) Under the condition of plasma activity promotion, a carbon deposition precursor of 10% hydrogen-50% argon-40% methane is passed at a flow rate of 0.1 m / s, and a carbon deposition reaction is carried out with the silicon-carbon microspheres at 400℃ for 2h to obtain a high-first-efficiency high-tapped-density silicon-carbon negative electrode material (as shown in Figure 1 ).

[0051] The obtained high-first-efficiency high-tapped-density silicon-carbon negative electrode material is subjected to performance testing, and the tapped density is as high as 0.85 g / cm 3 , and the first coulombic efficiency of the negative electrode material can reach 88.8%.

[0052] Example 2

[0053] A method for preparing a high-first-efficiency high-tapped-density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste, and the specific steps are as follows:

[0054] (1) The waste silicon slag generated in the photovoltaic silicon production process is crushed, ball milled and sand milled to obtain silicon powder of about 1 μm; the silicon powder is acid washed in a mixed solution of 1 mol / L hydrofluoric acid and 1 mol / L hydrochloric acid at a liquid-to-solid ratio of 10 mL:1 g for 8h to obtain a pretreated silicon material; the pretreated silicon material is mixed with 1wt% Li2CO3 of the pre-lithiated silicon material by ball milling, and then reacted at 800℃ in an argon atmosphere for 2h to obtain a pre-lithiated silicon material.

[0055] (2) The pre-lithiated silicon material, graphite, graphene, additive CuO, pore-forming agent CaCl2 and ethanol are mixed according to a mass ratio of 30:50:5:1:1:800 to obtain a precursor solution; the precursor solution is added at a feeding speed of 2 mL / min, and argon is added at an air feeding speed of 5 mL / min; the precursor solution is subjected to spray self-assembly under the condition of argon protection at 120℃ to obtain silicon-carbon microspheres;

[0056] (3) Under the condition of plasma activity promotion, a carbon deposition precursor of 20% hydrogen-20% argon-60% ethane is passed at a flow rate of 10 m / s, and a carbon deposition reaction is carried out with the silicon-carbon microspheres at 600℃ for 2h to obtain a high-first-efficiency high-tapped-density silicon-carbon negative electrode material (as shown in Figure 2 ).

[0057] The obtained high initial efficiency high tap density silicon-carbon negative electrode material is tested for performance, and the tap density is as high as 0.90 g / cm 3 , and the initial coulombic efficiency as a negative electrode material can reach 91.2%.

[0058] Example 3

[0059] A method for preparing a high initial efficiency high tap density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste, the specific steps are as follows:

[0060] (1) The waste silicon slag generated in the photovoltaic silicon production process is crushed, ball milled and sand milled to obtain silicon powder of about 2 μm. The silicon powder is placed in a 4 mol / L hydrofluoric acid solution with a liquid-solid ratio of 8 mL:1 g for acid washing for 6 h to obtain pretreated silicon material. The pretreated silicon material is mixed with 0.1 wt% LiCl of the pre-lithiated silicon material by ball milling, and then reacted at 800°C under argon atmosphere for 2 h to obtain the pre-lithiated silicon material.

[0061] (2) The pre-lithiated silicon material, graphite, carbon nanotube, additive Fe(NO3)3, pore-forming agent LiCl and water are mixed according to the mass fraction ratio of 60:60:1:0.5:2:2000 to obtain a precursor solution; the precursor solution is added at a feeding speed of 5 mL / min, and argon is added at a gas feeding speed of 2 mL / min, and the precursor solution is sprayed and self-assembled at 150°C under argon protection to obtain silicon-carbon microspheres;

[0062] (3) A carbon deposition precursor of 40% hydrogen-30% argon-30% acetylene is introduced at a flow rate of 5 m / s, and a carbon deposition reaction is carried out with the silicon-carbon microspheres at 1200°C for 0.5 h to obtain a high initial efficiency high tap density silicon-carbon negative electrode material (as shown in Figure 3 ).

[0063] The obtained high initial efficiency high tap density silicon-carbon negative electrode material is tested for performance, and the tap density is as high as 0.87 g / cm 3 , and the initial coulombic efficiency as a negative electrode material can reach 88.4%.

[0064] Example 4

[0065] A method for preparing a high initial efficiency high tap density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste, the specific steps are as follows:

[0066] (1) The cutting silicon waste of about 1 μm generated in the photovoltaic silicon production process is sand ground to obtain silicon powder of about 0.05 μm, and the silicon powder is placed in a 0.1 mol / L hydrofluoric acid solution for acid washing for 0.5 h at a liquid-solid ratio of 5 mL:1 g to obtain pretreated silicon material; the pretreated silicon material and the prelithiated silicon material are mixed with 10% LiOH aqueous solution with a mass fraction of 0.1 wt% by stirring, and after filtration, the mixture is reacted at 60°C in an air atmosphere for 1 h to obtain the prelithiated silicon material.

[0067] (2) The prelithiated silicon material, graphite, pitch, additive TiO2, pore-forming agent MgCl2, and ethanol are mixed according to a mass ratio of 10:20:10:5:1:200 to obtain a precursor solution; the precursor solution is added at a feeding speed of 5 mL / min, and nitrogen is added at a feeding speed of 2 mL / min; the precursor solution is sprayed and self-assembled under the condition of nitrogen protection at 150°C to obtain silicon-carbon microspheres.

[0068] (3) Under the condition of plasma activity promotion, 40% hydrogen-50% argon-10% propyne carbon deposition precursor is passed at a flow rate of 10 m / s, and a carbon deposition reaction is performed with the silicon-carbon microspheres at 600°C for 2 h to obtain a high-first-efficiency high-tapped-density silicon-carbon negative electrode material (as shown in Figure 4 ).

[0069] The obtained high-first-efficiency high-tapped-density silicon-carbon negative electrode material is tested for performance, and the tapped density is as high as 0.92 g / cm 3 , and the first coulombic efficiency of the material as a negative electrode material can reach 89.5%.

[0070] Example 5

[0071] A method for preparing a high-first-efficiency high-tapped-density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste, and the specific steps are as follows:

[0072] (1) Submicron (0.3-0.5 μm) cutting silicon waste generated in the photovoltaic silicon production process is placed in a 0.5 mol / L hydrofluoric acid solution for acid washing for 0.2 h at a liquid-solid ratio of 6 mL:1 g to obtain pretreated silicon material; the pretreated silicon material and the prelithiated silicon material are mixed with 10% LiNO3 aqueous solution with a mass fraction of 1 wt% by aqueous solution stirring, and after filtration, the mixture is reacted at 200°C in an argon atmosphere for 5 h to obtain the prelithiated silicon material.

[0073] (2) The pre-lithiated silicon material, graphite, phenolic resin, polydopamine, additive Ni(NO3)2, pore-forming agent MgCl2 and water are mixed according to a mass ratio of 50:30:5:5:5:2:1000 to obtain a precursor solution; the precursor solution is added at a feeding speed of 2mL / min, and nitrogen is added at a gas feeding speed of 50mL / min, and the precursor solution is subjected to spray self-assembly under the condition of 300℃ and nitrogen protection to obtain silicon-carbon microspheres;

[0074] (3) The carbon deposition precursor of 20% hydrogen-30% argon-50% acetylene is passed at a flow rate of 5m / s, and the silicon-carbon microspheres are subjected to carbon deposition reaction at 1200℃ for 1h to obtain a high-first-efficiency high-tapped-density silicon-carbon negative electrode material (as shown in Figure 5 ).

[0075] The obtained high-first-efficiency high-tapped-density silicon-carbon negative electrode material is subjected to performance test, and the tapped density is as high as 0.81g / cm 3 , and the first coulombic efficiency of the negative electrode material can reach 90.5%.

[0076] It can be known from the above examples that the present application provides a method for preparing a high-first-efficiency high-tapped-density silicon-carbon negative electrode material from photovoltaic crystalline silicon waste. The present application first removes impurities by pretreating the photovoltaic crystalline silicon waste, and constructs a lithium silicate solid-state electrolyte by in-situ pre-lithiation treatment of the pretreated photovoltaic crystalline silicon waste; the pre-lithiated silicon material is subjected to spray self-assembly to obtain high-sphericity silicon-carbon microspheres; the silicon-carbon microspheres are introduced into a dense carbon skeleton by fluidized bed carbon deposition to finally obtain a high-first-efficiency high-tapped-density high-sphericity silicon-carbon negative electrode material. The present application provides a new idea and new path for value-added recycling of photovoltaic industry crystalline silicon waste and construction of high-performance lithium ion batteries.

[0077] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a high first efficiency high tap density silicon-carbon anode material from photovoltaic crystalline silicon scrap, characterized in that, The method comprises the following steps: (1) in-situ pre-lithiation treatment of photovoltaic crystalline silicon waste to obtain pre-lithiated silicon material; (2) mixing the pre-lithiated silicon material, carbon source, additive, pore-forming agent and solvent to obtain a precursor solution, and performing spray self-assembly on the precursor solution to obtain silicon-carbon microspheres; (3) carbon deposition reaction of the silicon-carbon microspheres to obtain a high-capacity and high-tapped density silicon-carbon negative electrode material; The lithium source used in the in-situ pre-lithiation treatment includes a solid-phase lithium source and / or a liquid-phase lithium source, and the lithium source contains one or more of LiCl, LiOH, Li2CO3, Li2SO4, LiNa, LiBr, LiI, LiC2H3O2, LiNO3, Li3PO4 and LiHSO4, the mass fraction of the liquid-phase lithium source is 0.1% to 20%, and the addition amount of the lithium source is 0.1 to 10 wt% of the pre-lithiated silicon material; The temperature of the in-situ pre-lithiation treatment is 60 to 1000 DEG C, and the time of the in-situ pre-lithiation treatment is 0.1 to 20 h; The feeding speed of the spray self-assembly is 0.01 to 100 mL / min, the gas inlet speed is 0.1 to 100 mL / min, the gas includes one or more of air, argon and nitrogen, and the temperature of the spray self-assembly is 100 to 300 DEG C.

2. The method of claim 1, wherein the method is characterized by: In the step (1), the photovoltaic crystalline silicon waste is obtained after pretreatment of waste silicon slag and cutting silicon waste generated in the photovoltaic silicon production process.

3. The method of claim 2, wherein the method is characterized by: The pretreatment includes acid pickling, and the acid pickling solution includes one or more of hydrofluoric acid, hydrochloric acid, nitric acid and sulfuric acid, the concentration of the acid pickling solution is 0.1 to 8 mol / L, the acid pickling time is 0.1 to 8 h, and the liquid-solid ratio is 3 to 10 mL:1 g.

4. The method of claim 3, wherein the method is characterized by: The pretreatment also includes ball milling or sand milling, and the particle size distribution of the photovoltaic crystalline silicon waste after ball milling or sand milling is 0.05 to 5 μm.

5. The method of claim 1 or 4 for the preparation of high first efficiency high tap density silicon-carbon negative electrode material from photovoltaic crystalline silicon scrap, characterized in that, In the step (1), the atmosphere of the in-situ pre-lithiation treatment includes one or more of air, argon and nitrogen.

6. The method of claim 1, wherein the method of preparing high first- efficiency high tap-density silicon-carbon anode material from photovoltaic crystalline silicon scrap, is characterized by, In the step (2), the mass ratio of the pre-lithiated silicon material, carbon source, additive, pore-forming agent and solvent is 1 to 80:1 to 60:0.1 to 5:0.1 to 5:10 to 2000.

7. The method of claim 1, wherein the method is characterized by: In the step (2), the carbon source includes at least two of graphite, pitch, glucose, graphene, carbon nanotube, phenolic resin and polydopamine, the solvent is one or more of deionized water, methanol, ethanol, propanol, butanol, ethylene glycol and propylene glycol, the additive includes one or more of TiO2, CuO, Ag, Fe(NO3)3 and Ni(NO3)2, and the pore-forming agent includes one or more of LiCl, Na2CO3, KCl, CaCl2, NaCl and MgCl2.

8. The method of claim 1, wherein the method is characterized by: In the step (3), the carbon deposition precursor in the carbon deposition reaction contains active gas, hydrogen and argon, wherein the proportion of hydrogen is 10 to 40%, the proportion of argon is 20 to 50%, and the proportion of active gas is 10 to 60%, the active gas includes one or more of methane, ethane, propane, acetylene, propyne and carbon monoxide, and the flow rate of the carbon deposition precursor is 0.1 to 10 m / s.

9. The method of claim 1 or 8, wherein the photovoltaic crystalline silicon scrap is prepared into a high initial efficiency and high tap density silicon-carbon negative electrode material, characterized in that, In the step (3), the temperature of the carbon deposition reaction is 400-1200 DEG C, and the time of the carbon deposition reaction is 0.1-12h. In the step (3), the temperature of the carbon deposition reaction is 400-1200 DEG C, and the time of the carbon deposition reaction is 0.1

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