CN111661844A - Preparation method of high-gram-capacity and high-first-efficiency silicon-carbon lithium ion battery cathode material - Google Patents

Abstract

The invention provides a preparation method of a high-gram-capacity and high-first-efficiency silicon-carbon lithium ion battery cathode material. The silicon-carbon negative electrode material prepared by the method has the advantages of high gram volume, high first effect and uniform particle size distribution, and in addition, the preparation method is convenient to operate, simple in process and convenient for commercial popularization.

Description

Preparation method of anode material for high gram capacity and high first-efficiency silicon carbon lithium ion battery

technical field

The invention relates to the field of lithium ion batteries, in particular to the field of preparation of negative electrode materials for silicon carbon lithium ion batteries.

Background technique

With the rapid promotion of lithium-ion batteries in various fields of use, the requirements for high energy density and high power density are becoming increasingly prominent. At present, the anode materials of commercial lithium-ion batteries are mainly graphite, but the theoretical capacity of graphite materials is too low to be only 372mAh/g, which can no longer meet the needs of lithium-ion battery development. The theoretical capacity of silicon is 4200mAh/g, and it has the advantages of low discharge voltage and good safety. Therefore, the research of silicon carbon anode material has become a hot spot in the research of battery materials. However, nano-silicon materials are easy to agglomerate during the preparation process, resulting in capacity loss, low efficiency, and difficult electrode processing. How to reduce the agglomeration of nano-silicon particles of silicon-carbon anode materials has become the focus of industry research.

SUMMARY OF THE INVENTION

The present invention provides a method for preparing a high gram capacity and high first-efficiency silicon-carbon lithium ion battery negative electrode material, and the silicon-carbon negative electrode material prepared by the method has the advantages of high gram-capacity and high first-efficiency.

The preparation method of the silicon-carbon lithium-ion battery negative electrode material of the present invention is as follows:

1. the preparation method of the silicon carbon lithium ion battery negative electrode material of the present invention is as follows:

A: put deionized water into the conical stirring steam-drying mixer;

B: add the cetyl ammonium bromide that graphite content is 0.1%～6.0% in the deionized water of A step, and stir 0.5h～2h, and stirring speed is 110～320r/min;

After the stirring in steps C:B, graphite and silicon are added, wherein the mass ratio of graphite and silicon is 1:1 to 5:1, and nitrogen is introduced, stirred for 2 to 4 hours, and the rotating speed is 110 to 320 r/min;

D: turn off nitrogen, add nano-silicon slurry to the mixture in step C, wherein the solvent is alcohol, the solid content is 6% to 10%, and the mass of silicon is 6kg,

E: add 5-15% solid glucose of silicon and graphite quality to the mixture in step D, feed nitrogen, rotate speed 110-320r/min, and stir for 2-6h;

F: the mixture in step E is evaporated to dryness by heating, wherein the heating temperature is 120°C to 260°C, and the stirring speed is 110 to 320 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the temperature rise process is that the nitrogen flow rate is 6～12L/min, and the temperature rises to 900～1100°C, and the temperature rise rate is 3～12°C/min; the heat preservation process is The nitrogen flow rate is 4~8L/min, the holding time is 3~8h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

Description of drawings

Fig. 1 is the charge-discharge curve of the button battery made of the material prepared in Example 1 of the present invention under constant current 0.1C;

Fig. 2 is the XRD pattern of the material prepared in Example 1 of the present invention.

Detailed ways

Example 1

A preparation method of a silicon carbon negative electrode material for a lithium ion battery, specifically comprising the following steps:

A: take by weighing 48kg deionized water and add conical stirring steam-dry mixer;

B: take by weighing 18g hexadecyl ammonium bromide and add conical stirring and evaporate to dryness mixer, rotating speed 200r/min, stir 0.5h;

C: take by weighing 12kg graphite and add in the conical stirring and drying mixer of step B, stir for 2h;

D: adding the nano-silicon solution 60kg of 10% in solid content to the C step mixture, wherein the Dv50 of nano-silicon is 60nm, and the organic solvent is alcohol, stirred for 3h;

E: add 10% solid glucose of silicon and graphite mass to the mixture in step D, pass nitrogen, rotate speed 200r/min, and stir for 3h;

F: Evaporate the mixture of step E to dryness by heating, wherein the heating temperature is 240 ° C, and the stirring speed is 200 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the heating process is that the nitrogen flow rate is 12L/min, the temperature is raised to 900°C, and the heating rate is 6°C/min; the heating process is that the nitrogen flow rate is 8L/min , the holding time is 5h, the cooling process is natural cooling, and the nitrogen flow rate does not change during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

Fig. 1 is the charge-discharge curve of the button battery made of the material prepared in Example 1 of the present invention under constant current 0.1C, it can be seen from Fig. 1 that the gram capacity of this material is 1350mAh/g, and the first effect can reach 90.1%;

Fig. 2 is the XRD pattern of the material prepared in Example 1 of the present invention, it can be seen from Fig. 2 that this material has only the diffraction peaks of graphite and silicon, indicating that in the preparation process, the nano-silicon is not oxidized;

The prepared silicon carbon anode material is mixed with SP, SBR, and CMC according to the mass ratio of 70:10:10:10, and the mixture is mixed into slurry with 1-methyl-2-pyrrolidone, which is uniformly coated on the copper foil. , 70 ℃ vacuum drying for 24h, the battery pole piece was obtained. Then use the lithium sheet as the counter electrode, use the LiPF6 four-component mixed solvent (EC:DMC:VC:FEC=1:1:1:1) with a molar concentration of 1.1mol/L as the electrolyte, and use the polypropylene film as the diaphragm, A CR2025 button half-cell was assembled in a vacuum glove box and discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C.

Example 2

A preparation method of a silicon carbon negative electrode material for a lithium ion battery, specifically comprising the following steps:

A: Weigh 18kg deionized water and add conical stirring steam-dry mixer;

B: take by weighing 18g hexadecyl ammonium bromide and add conical stirring and evaporate to dryness mixer, rotating speed 200r/min, stir 0.5h;

C: take by weighing 12kg graphite and add in the conical stirring and drying mixer of step B, stir for 2h;

D: adding the nano-silicon solution 60kg of 10% in solid content to the C step mixture, wherein the Dv50 of nano-silicon is 60nm, and the organic solvent is alcohol, stirred for 3h;

E: add 10% solid glucose of silicon and graphite mass to the mixture in step D, pass nitrogen, rotate speed 200r/min, and stir for 3h;

F: Evaporate the mixture of step E to dryness by heating, wherein the heating temperature is 240 ° C, and the stirring speed is 200 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the heating process is that the nitrogen flow rate is 12L/min, the temperature is raised to 900°C, and the heating rate is 6°C/min; the heating process is that the nitrogen flow rate is 8L/min , the holding time is 5h, the cooling process is natural cooling, and the nitrogen flow rate does not change during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

The prepared silicon carbon anode material is mixed with SP, SBR, and CMC according to the mass ratio of 70:10:10:10, and the mixture is mixed into slurry with 1-methyl-2-pyrrolidone, which is uniformly coated on the copper foil. , 70 ℃ vacuum drying for 24h, the battery pole piece was obtained. Then use the lithium sheet as the counter electrode, use the LiPF6 four-component mixed solvent (EC:DMC:VC:FEC=1:1:1:1) with a molar concentration of 1.1mol/L as the electrolyte, and use the polypropylene film as the diaphragm, A CR2025 button half-cell was assembled in a vacuum glove box and discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C.

Example 3

A preparation method of a silicon carbon negative electrode material for a lithium ion battery, specifically comprising the following steps:

A: take by weighing 48kg deionized water and add conical stirring steam-dry mixer;

B: take by weighing 540g hexadecyl ammonium bromide and add the conical stirring steam-drying mixer, rotating speed 200r/min, stir 0.5h;

C: take by weighing 12kg graphite and add in the conical stirring and drying mixer of step B, stir for 2h;

D: adding the nano-silicon solution 60kg of 10% in solid content to the C step mixture, wherein the Dv50 of nano-silicon is 60nm, and the organic solvent is alcohol, stirred for 3h;

E: add 10% solid glucose of silicon and graphite mass to the mixture in step D, pass nitrogen, rotate speed 200r/min, and stir for 3h;

F: Evaporate the mixture of step E to dryness by heating, wherein the heating temperature is 240 ° C, and the stirring speed is 200 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the heating process is that the nitrogen flow rate is 12L/min, the temperature is raised to 900°C, and the heating rate is 6°C/min; the heating process is that the nitrogen flow rate is 8L/min , the holding time is 5h, the cooling process is natural cooling, and the nitrogen flow rate does not change during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

The prepared silicon carbon anode material is mixed with SP, SBR, and CMC according to the mass ratio of 70:10:10:10, and the mixture is mixed into slurry with 1-methyl-2-pyrrolidone, which is uniformly coated on the copper foil. , 70 ℃ vacuum drying for 24h, the battery pole piece was obtained. Then use the lithium sheet as the counter electrode, use the LiPF6 four-component mixed solvent (EC:DMC:VC:FEC=1:1:1:1) with a molar concentration of 1.1mol/L as the electrolyte, and use the polypropylene film as the diaphragm, A CR2025 button half-cell was assembled in a vacuum glove box and discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C.

Example 4

A preparation method of a silicon carbon negative electrode material for a lithium ion battery, specifically comprising the following steps:

A: take by weighing 48kg deionized water and add conical stirring steam-dry mixer;

B: take by weighing 18g hexadecyl ammonium bromide and add conical stirring and evaporation-dry mixer, rotating speed 250r/min, stir 0.5h;

C: take by weighing 12kg graphite and add in the conical stirring and drying mixer of step B, stir for 2h;

D: adding the nano-silicon solution 60kg of 10% in solid content to the C step mixture, wherein the Dv50 of nano-silicon is 60nm, and the organic solvent is alcohol, stirred for 3h;

E: add 10% solid glucose of silicon and graphite mass to the mixture in step D, pass nitrogen, rotate speed 250r/min, and stir for 3h;

F: the mixture in step E is evaporated to dryness by heating, wherein the heating temperature is 240 ° C, and the stirring speed is 250 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the heating process is that the nitrogen flow rate is 12L/min, the temperature is raised to 900°C, and the heating rate is 6°C/min; the heating process is that the nitrogen flow rate is 8L/min , the holding time is 5h, the cooling process is natural cooling, and the nitrogen flow rate does not change during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

The prepared silicon carbon anode material is mixed with SP, SBR, and CMC according to the mass ratio of 70:10:10:10, and the mixture is mixed into slurry with 1-methyl-2-pyrrolidone, which is uniformly coated on the copper foil. , 70 ℃ vacuum drying for 24h, the battery pole piece was obtained. Then use the lithium sheet as the counter electrode, use the LiPF6 four-component mixed solvent (EC:DMC:VC:FEC=1:1:1:1) with a molar concentration of 1.1mol/L as the electrolyte, and use the polypropylene film as the diaphragm, A CR2025 button half-cell was assembled in a vacuum glove box and discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C.

Example 5

A preparation method of a silicon carbon negative electrode material for a lithium ion battery, specifically comprising the following steps:

A: take by weighing 48kg deionized water and add conical stirring steam-dry mixer;

B: take by weighing 18g hexadecyl ammonium bromide and add conical stirring and evaporate to dryness mixer, rotating speed 200r/min, stir 0.5h;

C: take by weighing 12kg graphite and add in the conical stirring and drying mixer of step B, stir for 2.5h;

D: adding the nano-silicon solution 60kg of 10% in solid content to the C step mixture, wherein the Dv50 of nano-silicon is 60nm, and the organic solvent is alcohol, stirred for 3h;

E: E: Add 10% solid glucose of silicon and graphite mass to the mixture in step D, pass nitrogen, rotate speed 200r/min, and stir for 3h;

F: Evaporate the mixture of step E to dryness by heating, wherein the heating temperature is 240 ° C, and the stirring speed is 200 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the heating process is that the nitrogen flow rate is 12L/min, the temperature is raised to 900°C, and the heating rate is 6°C/min; the heating process is that the nitrogen flow rate is 8L/min , the holding time is 5h, the cooling process is natural cooling, and the nitrogen flow rate does not change during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

The prepared silicon carbon anode material is mixed with SP, SBR, and CMC according to the mass ratio of 70:10:10:10, and the mixture is mixed into slurry with 1-methyl-2-pyrrolidone, which is uniformly coated on the copper foil. , 70 ℃ vacuum drying for 24h, the battery pole piece was obtained. Then use the lithium sheet as the counter electrode, use the LiPF6 four-component mixed solvent (EC:DMC:VC:FEC=1:1:1:1) with a molar concentration of 1.1mol/L as the electrolyte, and use the polypropylene film as the diaphragm, A CR2025 button half-cell was assembled in a vacuum glove box and discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C.

Example 6

A preparation method of a silicon carbon negative electrode material for a lithium ion battery, specifically comprising the following steps:

A: take by weighing 48kg deionized water and add conical stirring steam-dry mixer;

B: take by weighing 18g hexadecyl ammonium bromide and add conical stirring and evaporate to dryness mixer, rotating speed 200r/min, stir 0.5h;

C: take by weighing 12kg graphite and add in the conical stirring and drying mixer of step B, stir for 2h;

D: adding the nano-silicon solution 60kg of 10% in solid content to the C step mixture, wherein the Dv50 of nano-silicon is 60nm, and the organic solvent is alcohol, stirred for 3h;

E: add 15% solid glucose of silicon and graphite quality to the mixture in step D, pass nitrogen, rotate speed 200r/min, and stir for 3h;

F: Evaporate the mixture of step E to dryness by heating, wherein the heating temperature is 240 ° C, and the stirring speed is 200 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the heating process is that the nitrogen flow rate is 12L/min, the temperature is raised to 900°C, and the heating rate is 6°C/min; the heating process is that the nitrogen flow rate is 8L/min , the holding time is 5h, the cooling process is natural cooling, and the nitrogen flow rate does not change during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

The prepared silicon carbon anode material is mixed with SP, SBR, and CMC according to the mass ratio of 70:10:10:10, and the mixture is mixed into slurry with 1-methyl-2-pyrrolidone, which is uniformly coated on the copper foil. , 70 ℃ vacuum drying for 24h, the battery pole piece was obtained. Then use the lithium sheet as the counter electrode, use the LiPF6 four-component mixed solvent (EC:DMC:VC:FEC=1:1:1:1) with a molar concentration of 1.1mol/L as the electrolyte, and use the polypropylene film as the diaphragm, A CR2025 button half-cell was assembled in a vacuum glove box and discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C.

Example 7

A preparation method of a silicon carbon negative electrode material for a lithium ion battery, specifically comprising the following steps:

A: take by weighing 48kg deionized water and add conical stirring steam-dry mixer;

B: take by weighing 18g hexadecyl ammonium bromide and add conical stirring and evaporate to dryness mixer, rotating speed 200r/min, stir 0.5h;

C: take by weighing 12kg graphite and add in the conical stirring and drying mixer of step B, stir for 2h;

D: adding the nano-silicon solution 60kg of 10% in solid content to the C step mixture, wherein the Dv50 of nano-silicon is 60nm, and the organic solvent is alcohol, stirred for 3h;

E: add 10% solid glucose of silicon and graphite mass to the mixture in step D, pass nitrogen, rotate speed 200r/min, and stir for 3h;

F: Evaporate the mixture in step E to dryness by heating, wherein the heating temperature is 220 ° C, and the stirring speed is 200 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the heating process is that the nitrogen flow rate is 12L/min, the temperature is raised to 900°C, and the heating rate is 6°C/min; the heating process is that the nitrogen flow rate is 8L/min , the holding time is 5h, the cooling process is natural cooling, and the nitrogen flow rate does not change during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

The prepared silicon carbon anode material is mixed with SP, SBR, and CMC according to the mass ratio of 70:10:10:10, and the mixture is mixed into slurry with 1-methyl-2-pyrrolidone, which is uniformly coated on the copper foil. , 70 ℃ vacuum drying for 24h, the battery pole piece was obtained. Then use the lithium sheet as the counter electrode, use the LiPF6 four-component mixed solvent (EC:DMC:VC:FEC=1:1:1:1) with a molar concentration of 1.1mol/L as the electrolyte, and use the polypropylene film as the diaphragm, A CR2025 button half-cell was assembled in a vacuum glove box and discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C.

Example 8

A preparation method of a silicon carbon negative electrode material for a lithium ion battery, specifically comprising the following steps:

A: take by weighing 48kg deionized water and add conical stirring steam-dry mixer;

B: take by weighing 18g hexadecyl ammonium bromide and add conical stirring and evaporate to dryness mixer, rotating speed 200r/min, stir 0.5h;

C: take by weighing 12kg graphite and add in the conical stirring and drying mixer of step B, stir for 2h;

D: adding the nano-silicon solution 60kg of 10% in solid content to the C step mixture, wherein the Dv50 of nano-silicon is 60nm, and the organic solvent is alcohol, stirred for 3h;

E: add 10% solid glucose of silicon and graphite mass to the mixture in step D, pass nitrogen, rotate speed 200r/min, and stir for 3h;

F: Evaporate the mixture of step E to dryness by heating, wherein the heating temperature is 240 ° C, and the stirring speed is 200 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the heating process is that the nitrogen flow rate is 12L/min, and the temperature is raised to 1000°C, and the heating rate is 6°C/min; the heating process is that the nitrogen flow rate is 8L/min , the holding time is 5h, the cooling process is natural cooling, and the nitrogen flow rate does not change during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

The prepared silicon carbon anode material is mixed with SP, SBR, and CMC according to the mass ratio of 70:10:10:10, and the mixture is mixed into slurry with 1-methyl-2-pyrrolidone, which is uniformly coated on the copper foil. , 70 ℃ vacuum drying for 24h, the battery pole piece was obtained. Then use the lithium sheet as the counter electrode, use the LiPF6 four-component mixed solvent (EC:DMC:VC:FEC=1:1:1:1) with a molar concentration of 1.1mol/L as the electrolyte, and use the polypropylene film as the diaphragm, A CR2025 button half-cell was assembled in a vacuum glove box and discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C.

Example 9

A preparation method of a silicon carbon negative electrode material for a lithium ion battery, specifically comprising the following steps:

A: Weigh 48kg deionized water and add conical stirring steam-dry mixer;

B: take by weighing 18g hexadecyl ammonium bromide and add conical stirring and evaporate to dryness mixer, rotating speed 200r/min, stir 0.5h;

C: take by weighing 12kg graphite and add in the conical stirring and drying mixer of step B, stir for 2h;

D: adding the nano-silicon solution 60kg of 10% in solid content to the C step mixture, wherein the Dv50 of nano-silicon is 60nm, and the organic solvent is alcohol, stirred for 3h;

E: add 10% solid glucose of silicon and graphite mass to the mixture in step D, pass nitrogen, rotate speed 200r/min, and stir for 3h;

F: Evaporate the mixture of step E to dryness by heating, wherein the heating temperature is 240 ° C, and the stirring speed is 200 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the heating process is that the nitrogen flow rate is 12L/min, and the temperature is raised to 900°C, and the heating rate is 3°C/min; the heat preservation process is that the nitrogen flow rate is 8L/min , the holding time is 5h, the cooling process is natural cooling, and the nitrogen flow rate does not change during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

The prepared silicon carbon anode material is mixed with SP, SBR, and CMC according to the mass ratio of 70:10:10:10, and the mixture is mixed into slurry with 1-methyl-2-pyrrolidone, which is uniformly coated on the copper foil. , 70 ℃ vacuum drying for 24h, the battery pole piece was obtained. Then use the lithium sheet as the counter electrode, use the LiPF6 four-component mixed solvent (EC:DMC:VC:FEC=1:1:1:1) with a molar concentration of 1.1mol/L as the electrolyte, and use the polypropylene film as the diaphragm, A CR2025 button half-cell was assembled in a vacuum glove box and discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C.

Example 10

A preparation method of a silicon carbon negative electrode material for a lithium ion battery, specifically comprising the following steps:

A: take by weighing 48kg deionized water and add conical stirring steam-dry mixer;

B: take by weighing 18g hexadecyl ammonium bromide and add conical stirring and evaporate to dryness mixer, rotating speed 200r/min, stir 0.5h;

C: take by weighing 12kg graphite and add in the conical stirring and drying mixer of step B, stir for 2h;

D: adding the nano-silicon solution 60kg of 10% in solid content to the C step mixture, wherein the Dv50 of nano-silicon is 60nm, and the organic solvent is alcohol, stirred for 3h;

E: add 10% solid glucose of silicon and graphite mass to the mixture in step D, pass nitrogen, rotate speed 200r/min, and stir for 3h;

F: Evaporate the mixture of step E to dryness by heating, wherein the heating temperature is 240 ° C, and the stirring speed is 200 r/min;

G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the temperature rise process is that the nitrogen flow rate is 12L/min, the temperature is raised to 900°C, and the temperature rise rate is 6°C/min; the heat preservation process is that the nitrogen flow rate is 4L/min , the holding time is 5h, the cooling process is natural cooling, and the nitrogen flow rate does not change during cooling;

H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

The prepared silicon carbon anode material is mixed with SP, SBR, and CMC according to the mass ratio of 70:10:10:10, and the mixture is mixed into slurry with 1-methyl-2-pyrrolidone, which is uniformly coated on the copper foil. , 70 ℃ vacuum drying for 24h, the battery pole piece was obtained. Then use the lithium sheet as the counter electrode, use the LiPF6 four-component mixed solvent (EC:DMC:VC:FEC=1:1:1:1) with a molar concentration of 1.1mol/L as the electrolyte, and use the polypropylene film as the diaphragm, A CR2025 button half-cell was assembled in a vacuum glove box, and was discharged to 5mV at a constant current of 0.1C, then discharged to 5mV at a constant current of 0.02C, and charged to 1.5V at a constant current of 0.1C.

Claims (1)

1. The preparation method of the anode material for high gram capacity and high first-efficiency silicon carbon lithium ion battery is as follows: A: put deionized water into the conical stirring steam-drying mixer; B: add the cetyl ammonium bromide that graphite content is 0.1%～6.0% in the deionized water of A step, and stir 0.5h～2h, and stirring speed is 110～320r/min; After the stirring in steps C:B, graphite and silicon are added, wherein the mass ratio of graphite and silicon is 1:1 to 5:1, and nitrogen is introduced, stirred for 2 to 4 hours, and the rotating speed is 110 to 320 r/min; D: turn off nitrogen, add nano-silicon slurry to the mixture in step C, wherein the solvent is alcohol, the solid content is 6% to 10%, and the mass of silicon is 6kg, E: add 5-15% solid glucose of silicon and graphite quality to the mixture in step D, feed nitrogen, rotate speed 110-320r/min, and stir for 2-6h; F: the mixture in step E is evaporated to dryness by heating, wherein the heating temperature is 120°C to 260°C, and the stirring speed is 110 to 320 r/min; G: the mixture obtained in step F is calcined in a box-type carbonization furnace, wherein the temperature rise process is that the nitrogen flow rate is 6～12L/min, and the temperature rises to 900～1100°C, and the temperature rise rate is 3～12°C/min; the heat preservation process is The nitrogen flow rate is 4~8L/min, the holding time is 3~8h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling; H: Pass the material precursor obtained in step F through a 300-mesh sieve to obtain a silicon-carbon negative electrode material for lithium ion batteries.

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