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 high-gram-capacity and high-first-efficiency silicon-carbon lithium ion battery cathode material

Technical Field

The invention relates to the field of lithium ion batteries, in particular to the field of preparation of silicon-carbon lithium ion battery cathode materials.

Background

With the rapid popularization of lithium ion batteries in various fields of use, the requirements for high energy density and high power density are increasingly prominent. The negative electrode material of the lithium ion battery which is commercialized at present mainly takes graphite, but the theoretical capacity of the graphite material is too low to be 372mAh/g, and the development requirement of the lithium ion battery cannot be met. The theoretical capacity of silicon is 4200mAh/g, and the silicon carbon anode material has the advantages of low discharge voltage, good safety and the like, so the research of the silicon carbon anode material becomes a hot spot in the research of battery materials. However, in the preparation process, the nano silicon material is easy to agglomerate, which causes the problems of capacity loss, low efficiency, difficult electrode processing and the like, and how to reduce the agglomeration of nano silicon particles of the silicon-carbon negative electrode material at a time becomes the focus of research in the industry.

Disclosure of Invention

The invention provides a preparation method of a high-gram-capacity and high-first-efficiency silicon-carbon lithium ion battery cathode material.

The preparation method of the silicon-carbon lithium ion battery cathode material comprises the following steps:

1. the preparation method of the silicon-carbon lithium ion battery cathode material comprises the following steps:

a, adding deionized water into a conical stirring and evaporating mixer;

b, adding hexadecyl ammonium bromide with the graphite content of 0.1-6.0% into the deionized water obtained in the step A, and stirring for 0.5-2 h at the stirring speed of 110-320 r/min;

c, after stirring in the step B is finished, adding graphite and silicon, wherein the mass ratio of the graphite to the silicon is 1: 1-5: 1, introducing nitrogen, stirring for 2-4 hours, and rotating speed is 110-320 r/min;

d, closing nitrogen, adding the nano silicon slurry into the mixture obtained in the step C, wherein the solvent is alcohol, the solid content is 6-10%, the mass of silicon is 6kg,

e: adding solid glucose accounting for 5-15% of the mass of the silicon and graphite into the mixture obtained in the step D, introducing nitrogen, rotating at the speed of 110-320 r/min, and stirring for 2-6 h;

f: heating and evaporating the mixture obtained in the step E to dryness, wherein the heating temperature is 120-260 ℃, and the stirring speed is 110-320 r/min;

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

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

Drawings

FIG. 1 is a charge-discharge curve at a constant current of 0.1C for a coin cell made of the material prepared in example 1 of the present invention;

figure 2 is an XRD pattern of the material prepared in example 1 of the present invention.

Detailed Description

Example 1

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

weighing 48kg of deionized water, adding the deionized water into a conical stirring and evaporating mixer;

weighing 18g of hexadecyl ammonium bromide, adding into a conical stirring and evaporating mixer, stirring at the rotating speed of 200r/min for 0.5 h;

c, weighing 12kg of graphite, adding the graphite into the conical stirring and evaporating mixer in the step B, and stirring for 2 hours;

d, adding 60kg of nano-silicon solution with the solid content of 10% into the mixture obtained in the step C, wherein the Dv50 of the nano-silicon is 60nm, the organic solvent is alcohol, and stirring for 3 hours;

e: d, adding solid glucose accounting for 10% of the mass of the silicon and the graphite into the mixture obtained in the step D, introducing nitrogen, stirring at the rotating speed of 200r/min for 3 hours;

f: e, drying the mixture obtained in the step E by heating to dryness, wherein the heating temperature is 240 ℃, and the stirring speed is 200 r/min;

g: roasting the mixture obtained in the step F in a box-type carbonization furnace, wherein the temperature rise process is performed at the nitrogen flow rate of 12L/min, the temperature rises to 900 ℃, and the temperature rise rate is 6 ℃/min; the heat preservation process is that the nitrogen flow rate is 8L/min, the heat preservation time is 5h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

FIG. 1 is a charge-discharge curve of a coin cell made of the material prepared in example 1 of the present invention at a constant current of 0.1C, and it can be seen from FIG. 1 that the gram capacity of the material is 1350mAh/g, and the first effect can reach 90.1%;

FIG. 2 is an XRD pattern of the material prepared in example 1 of the present invention, and it can be seen from FIG. 2 that the material has only diffraction peaks of graphite and silicon, which indicates that nano-silicon is not oxidized during the preparation process;

mixing the prepared silicon-carbon negative electrode material with SP, SBR and CMC according to a mass ratio of 70:10:10:10, mixing the mixture into slurry by using 1-methyl-2-pyrrolidone, uniformly coating the slurry on copper foil, and carrying out vacuum drying at 70 ℃ for 24 hours to obtain the battery pole piece. And then a lithium sheet is taken as a counter electrode, a LiPF6 four-component mixed solvent (EC: DMC: VC: FEC ═ 1:1:1:1) with the molar concentration of 1.1mol/L is taken as an electrolyte, a polypropylene film is taken as a diaphragm, a CR2025 type button half cell is assembled in a vacuum glove box, and the cell is 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 comprises the following steps:

weighing 18kg of deionized water, adding the deionized water into a conical stirring and evaporating mixer;

weighing 18g of hexadecyl ammonium bromide, adding into a conical stirring and evaporating mixer, stirring at the rotating speed of 200r/min for 0.5 h;

c, weighing 12kg of graphite, adding the graphite into the conical stirring and evaporating mixer in the step B, and stirring for 2 hours;

d, adding 60kg of nano-silicon solution with the solid content of 10% into the mixture obtained in the step C, wherein the Dv50 of the nano-silicon is 60nm, the organic solvent is alcohol, and stirring for 3 hours;

e: d, adding solid glucose accounting for 10% of the mass of the silicon and the graphite into the mixture obtained in the step D, introducing nitrogen, stirring at the rotating speed of 200r/min for 3 hours;

f: e, drying the mixture obtained in the step E by heating to dryness, wherein the heating temperature is 240 ℃, and the stirring speed is 200 r/min;

g: roasting the mixture obtained in the step F in a box-type carbonization furnace, wherein the temperature rise process is performed at the nitrogen flow rate of 12L/min, the temperature rises to 900 ℃, and the temperature rise rate is 6 ℃/min; the heat preservation process is that the nitrogen flow rate is 8L/min, the heat preservation time is 5h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

Mixing the prepared silicon-carbon negative electrode material with SP, SBR and CMC according to a mass ratio of 70:10:10:10, mixing the mixture into slurry by using 1-methyl-2-pyrrolidone, uniformly coating the slurry on copper foil, and carrying out vacuum drying at 70 ℃ for 24 hours to obtain the battery pole piece. And then a lithium sheet is taken as a counter electrode, a LiPF6 four-component mixed solvent (EC: DMC: VC: FEC ═ 1:1:1:1) with the molar concentration of 1.1mol/L is taken as an electrolyte, a polypropylene film is taken as a diaphragm, a CR2025 type button half cell is assembled in a vacuum glove box, and the cell is 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 comprises the following steps:

weighing 48kg of deionized water, adding the deionized water into a conical stirring and evaporating mixer;

weighing 540g of hexadecyl ammonium bromide, adding the hexadecyl ammonium bromide into a conical stirring and evaporating mixer, stirring at the rotating speed of 200r/min for 0.5 h;

c, weighing 12kg of graphite, adding the graphite into the conical stirring and evaporating mixer in the step B, and stirring for 2 hours;

d, adding 60kg of nano-silicon solution with the solid content of 10% into the mixture obtained in the step C, wherein the Dv50 of the nano-silicon is 60nm, the organic solvent is alcohol, and stirring for 3 hours;

e: d, adding solid glucose accounting for 10% of the mass of the silicon and the graphite into the mixture obtained in the step D, introducing nitrogen, stirring at the rotating speed of 200r/min for 3 hours;

f: e, drying the mixture obtained in the step E by heating to dryness, wherein the heating temperature is 240 ℃, and the stirring speed is 200 r/min;

g: roasting the mixture obtained in the step F in a box-type carbonization furnace, wherein the temperature rise process is performed at the nitrogen flow rate of 12L/min, the temperature rises to 900 ℃, and the temperature rise rate is 6 ℃/min; the heat preservation process is that the nitrogen flow rate is 8L/min, the heat preservation time is 5h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

Mixing the prepared silicon-carbon negative electrode material with SP, SBR and CMC according to a mass ratio of 70:10:10:10, mixing the mixture into slurry by using 1-methyl-2-pyrrolidone, uniformly coating the slurry on copper foil, and carrying out vacuum drying at 70 ℃ for 24 hours to obtain the battery pole piece. And then a lithium sheet is taken as a counter electrode, a LiPF6 four-component mixed solvent (EC: DMC: VC: FEC ═ 1:1:1:1) with the molar concentration of 1.1mol/L is taken as an electrolyte, a polypropylene film is taken as a diaphragm, a CR2025 type button half cell is assembled in a vacuum glove box, and the cell is 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 comprises the following steps:

weighing 48kg of deionized water, adding the deionized water into a conical stirring and evaporating mixer;

weighing 18g of hexadecyl ammonium bromide, adding into a conical stirring and evaporating mixer, stirring at the rotating speed of 250r/min for 0.5 h;

c, weighing 12kg of graphite, adding the graphite into the conical stirring and evaporating mixer in the step B, and stirring for 2 hours;

d, adding 60kg of nano-silicon solution with the solid content of 10% into the mixture obtained in the step C, wherein the Dv50 of the nano-silicon is 60nm, the organic solvent is alcohol, and stirring for 3 hours;

e: d, adding solid glucose accounting for 10% of the mass of the silicon and the graphite into the mixture obtained in the step D, introducing nitrogen, stirring at the rotating speed of 250r/min for 3 hours;

f: e, drying the mixture obtained in the step E by heating to dryness, wherein the heating temperature is 240 ℃, and the stirring speed is 250 r/min;

g: roasting the mixture obtained in the step F in a box-type carbonization furnace, wherein the temperature rise process is performed at the nitrogen flow rate of 12L/min, the temperature rises to 900 ℃, and the temperature rise rate is 6 ℃/min; the heat preservation process is that the nitrogen flow rate is 8L/min, the heat preservation time is 5h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

Mixing the prepared silicon-carbon negative electrode material with SP, SBR and CMC according to a mass ratio of 70:10:10:10, mixing the mixture into slurry by using 1-methyl-2-pyrrolidone, uniformly coating the slurry on copper foil, and carrying out vacuum drying at 70 ℃ for 24 hours to obtain the battery pole piece. And then a lithium sheet is taken as a counter electrode, a LiPF6 four-component mixed solvent (EC: DMC: VC: FEC ═ 1:1:1:1) with the molar concentration of 1.1mol/L is taken as an electrolyte, a polypropylene film is taken as a diaphragm, a CR2025 type button half cell is assembled in a vacuum glove box, and the cell is 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 comprises the following steps:

weighing 48kg of deionized water, adding the deionized water into a conical stirring and evaporating mixer;

weighing 18g of hexadecyl ammonium bromide, adding into a conical stirring and evaporating mixer, stirring at the rotating speed of 200r/min for 0.5 h;

c, weighing 12kg of graphite, adding the graphite into the conical stirring and evaporating mixer in the step B, and stirring for 2.5 hours;

d, adding 60kg of nano-silicon solution with the solid content of 10% into the mixture obtained in the step C, wherein the Dv50 of the nano-silicon is 60nm, the organic solvent is alcohol, and stirring for 3 hours;

e: e: d, adding solid glucose accounting for 10% of the mass of the silicon and the graphite into the mixture obtained in the step D, introducing nitrogen, stirring at the rotating speed of 200r/min for 3 hours;

f: e, drying the mixture obtained in the step E by heating to dryness, wherein the heating temperature is 240 ℃, and the stirring speed is 200 r/min;

g: roasting the mixture obtained in the step F in a box-type carbonization furnace, wherein the temperature rise process is performed at the nitrogen flow rate of 12L/min, the temperature rises to 900 ℃, and the temperature rise rate is 6 ℃/min; the heat preservation process is that the nitrogen flow rate is 8L/min, the heat preservation time is 5h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

Mixing the prepared silicon-carbon negative electrode material with SP, SBR and CMC according to a mass ratio of 70:10:10:10, mixing the mixture into slurry by using 1-methyl-2-pyrrolidone, uniformly coating the slurry on copper foil, and carrying out vacuum drying at 70 ℃ for 24 hours to obtain the battery pole piece. And then a lithium sheet is taken as a counter electrode, a LiPF6 four-component mixed solvent (EC: DMC: VC: FEC ═ 1:1:1:1) with the molar concentration of 1.1mol/L is taken as an electrolyte, a polypropylene film is taken as a diaphragm, a CR2025 type button half cell is assembled in a vacuum glove box, and the cell is 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 comprises the following steps:

weighing 48kg of deionized water, adding the deionized water into a conical stirring and evaporating mixer;

weighing 18g of hexadecyl ammonium bromide, adding into a conical stirring and evaporating mixer, stirring at the rotating speed of 200r/min for 0.5 h;

c, weighing 12kg of graphite, adding the graphite into the conical stirring and evaporating mixer in the step B, and stirring for 2 hours;

d, adding 60kg of nano-silicon solution with the solid content of 10% into the mixture obtained in the step C, wherein the Dv50 of the nano-silicon is 60nm, the organic solvent is alcohol, and stirring for 3 hours;

e: d, adding solid glucose accounting for 15% of the mass of the silicon and the graphite into the mixture obtained in the step D, introducing nitrogen, stirring at the rotating speed of 200r/min for 3 hours;

f: e, drying the mixture obtained in the step E by heating to dryness, wherein the heating temperature is 240 ℃, and the stirring speed is 200 r/min;

g: roasting the mixture obtained in the step F in a box-type carbonization furnace, wherein the temperature rise process is performed at the nitrogen flow rate of 12L/min, the temperature rises to 900 ℃, and the temperature rise rate is 6 ℃/min; the heat preservation process is that the nitrogen flow rate is 8L/min, the heat preservation time is 5h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

Mixing the prepared silicon-carbon negative electrode material with SP, SBR and CMC according to a mass ratio of 70:10:10:10, mixing the mixture into slurry by using 1-methyl-2-pyrrolidone, uniformly coating the slurry on copper foil, and carrying out vacuum drying at 70 ℃ for 24 hours to obtain the battery pole piece. And then a lithium sheet is taken as a counter electrode, a LiPF6 four-component mixed solvent (EC: DMC: VC: FEC ═ 1:1:1:1) with the molar concentration of 1.1mol/L is taken as an electrolyte, a polypropylene film is taken as a diaphragm, a CR2025 type button half cell is assembled in a vacuum glove box, and the cell is 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 comprises the following steps:

weighing 48kg of deionized water, adding the deionized water into a conical stirring and evaporating mixer;

weighing 18g of hexadecyl ammonium bromide, adding into a conical stirring and evaporating mixer, stirring at the rotating speed of 200r/min for 0.5 h;

c, weighing 12kg of graphite, adding the graphite into the conical stirring and evaporating mixer in the step B, and stirring for 2 hours;

d, adding 60kg of nano-silicon solution with the solid content of 10% into the mixture obtained in the step C, wherein the Dv50 of the nano-silicon is 60nm, the organic solvent is alcohol, and stirring for 3 hours;

e: d, adding solid glucose accounting for 10% of the mass of the silicon and the graphite into the mixture obtained in the step D, introducing nitrogen, stirring at the rotating speed of 200r/min for 3 hours;

f: e, drying the mixture obtained in the step E by heating to dryness, wherein the heating temperature is 220 ℃, and the stirring speed is 200 r/min;

g: roasting the mixture obtained in the step F in a box-type carbonization furnace, wherein the temperature rise process is performed at the nitrogen flow rate of 12L/min, the temperature rises to 900 ℃, and the temperature rise rate is 6 ℃/min; the heat preservation process is that the nitrogen flow rate is 8L/min, the heat preservation time is 5h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

Mixing the prepared silicon-carbon negative electrode material with SP, SBR and CMC according to a mass ratio of 70:10:10:10, mixing the mixture into slurry by using 1-methyl-2-pyrrolidone, uniformly coating the slurry on copper foil, and carrying out vacuum drying at 70 ℃ for 24 hours to obtain the battery pole piece. And then a lithium sheet is taken as a counter electrode, a LiPF6 four-component mixed solvent (EC: DMC: VC: FEC ═ 1:1:1:1) with the molar concentration of 1.1mol/L is taken as an electrolyte, a polypropylene film is taken as a diaphragm, a CR2025 type button half cell is assembled in a vacuum glove box, and the cell is 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 comprises the following steps:

weighing 48kg of deionized water, adding the deionized water into a conical stirring and evaporating mixer;

weighing 18g of hexadecyl ammonium bromide, adding into a conical stirring and evaporating mixer, stirring at the rotating speed of 200r/min for 0.5 h;

c, weighing 12kg of graphite, adding the graphite into the conical stirring and evaporating mixer in the step B, and stirring for 2 hours;

d, adding 60kg of nano-silicon solution with the solid content of 10% into the mixture obtained in the step C, wherein the Dv50 of the nano-silicon is 60nm, the organic solvent is alcohol, and stirring for 3 hours;

e: d, adding solid glucose accounting for 10% of the mass of the silicon and the graphite into the mixture obtained in the step D, introducing nitrogen, stirring at the rotating speed of 200r/min for 3 hours;

f: e, drying the mixture obtained in the step E by heating to dryness, wherein the heating temperature is 240 ℃, and the stirring speed is 200 r/min;

g: roasting the mixture obtained in the step F in a box-type carbonization furnace, wherein the temperature rise process is performed at the nitrogen flow rate of 12L/min, the temperature rises to 1000 ℃ and the temperature rise rate is 6 ℃/min; the heat preservation process is that the nitrogen flow rate is 8L/min, the heat preservation time is 5h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

Mixing the prepared silicon-carbon negative electrode material with SP, SBR and CMC according to a mass ratio of 70:10:10:10, mixing the mixture into slurry by using 1-methyl-2-pyrrolidone, uniformly coating the slurry on copper foil, and carrying out vacuum drying at 70 ℃ for 24 hours to obtain the battery pole piece. And then a lithium sheet is taken as a counter electrode, a LiPF6 four-component mixed solvent (EC: DMC: VC: FEC ═ 1:1:1:1) with the molar concentration of 1.1mol/L is taken as an electrolyte, a polypropylene film is taken as a diaphragm, a CR2025 type button half cell is assembled in a vacuum glove box, and the cell is 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 comprises the following steps:

weighing 48kg of deionized water, adding the deionized water into a conical stirring and evaporating mixer;

weighing 18g of hexadecyl ammonium bromide, adding into a conical stirring and evaporating mixer, stirring at the rotating speed of 200r/min for 0.5 h;

c, weighing 12kg of graphite, adding the graphite into the conical stirring and evaporating mixer in the step B, and stirring for 2 hours;

d, adding 60kg of nano-silicon solution with the solid content of 10% into the mixture obtained in the step C, wherein the Dv50 of the nano-silicon is 60nm, the organic solvent is alcohol, and stirring for 3 hours;

e: d, adding solid glucose accounting for 10% of the mass of the silicon and the graphite into the mixture obtained in the step D, introducing nitrogen, stirring at the rotating speed of 200r/min for 3 hours;

f: e, drying the mixture obtained in the step E by heating to dryness, wherein the heating temperature is 240 ℃, and the stirring speed is 200 r/min;

g: roasting the mixture obtained in the step F in a box-type carbonization furnace, wherein the temperature rise process is performed at the nitrogen flow rate of 12L/min, the temperature rises to 900 ℃, and the temperature rise rate is 3 ℃/min; the heat preservation process is that the nitrogen flow rate is 8L/min, the heat preservation time is 5h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

Mixing the prepared silicon-carbon negative electrode material with SP, SBR and CMC according to a mass ratio of 70:10:10:10, mixing the mixture into slurry by using 1-methyl-2-pyrrolidone, uniformly coating the slurry on copper foil, and carrying out vacuum drying at 70 ℃ for 24 hours to obtain the battery pole piece. And then a lithium sheet is taken as a counter electrode, a LiPF6 four-component mixed solvent (EC: DMC: VC: FEC ═ 1:1:1:1) with the molar concentration of 1.1mol/L is taken as an electrolyte, a polypropylene film is taken as a diaphragm, a CR2025 type button half cell is assembled in a vacuum glove box, and the cell is 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 comprises the following steps:

weighing 48kg of deionized water, adding the deionized water into a conical stirring and evaporating mixer;

weighing 18g of hexadecyl ammonium bromide, adding into a conical stirring and evaporating mixer, stirring at the rotating speed of 200r/min for 0.5 h;

c, weighing 12kg of graphite, adding the graphite into the conical stirring and evaporating mixer in the step B, and stirring for 2 hours;

d, adding 60kg of nano-silicon solution with the solid content of 10% into the mixture obtained in the step C, wherein the Dv50 of the nano-silicon is 60nm, the organic solvent is alcohol, and stirring for 3 hours;

e: d, adding solid glucose accounting for 10% of the mass of the silicon and the graphite into the mixture obtained in the step D, introducing nitrogen, stirring at the rotating speed of 200r/min for 3 hours;

f: e, drying the mixture obtained in the step E by heating to dryness, wherein the heating temperature is 240 ℃, and the stirring speed is 200 r/min;

g: roasting the mixture obtained in the step F in a box-type carbonization furnace, wherein the temperature rise process is performed at the nitrogen flow rate of 12L/min, the temperature rises to 900 ℃, and the temperature rise rate is 6 ℃/min; the heat preservation process is that the nitrogen flow rate is 4L/min, the heat preservation time is 5h, the cooling process is natural cooling, and the nitrogen flow rate is unchanged during cooling;

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

Mixing the prepared silicon-carbon negative electrode material with SP, SBR and CMC according to a mass ratio of 70:10:10:10, mixing the mixture into slurry by using 1-methyl-2-pyrrolidone, uniformly coating the slurry on copper foil, and carrying out vacuum drying at 70 ℃ for 24 hours to obtain the battery pole piece. And then a lithium sheet is taken as a counter electrode, a LiPF6 four-component mixed solvent (EC: DMC: VC: FEC ═ 1:1:1:1) with the molar concentration of 1.1mol/L is taken as an electrolyte, a polypropylene film is taken as a diaphragm, a CR2025 type button half cell is assembled in a vacuum glove box, and the cell is 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 high-gram-capacity and high-first-efficiency silicon-carbon lithium ion battery cathode material comprises the following steps:

a, adding deionized water into a conical stirring and evaporating mixer;

b, adding hexadecyl ammonium bromide with the graphite content of 0.1-6.0% into the deionized water obtained in the step A, and stirring for 0.5-2 h at the stirring speed of 110-320 r/min;

c, after stirring in the step B is finished, adding graphite and silicon, wherein the mass ratio of the graphite to the silicon is 1: 1-5: 1, introducing nitrogen, stirring for 2-4 hours, and rotating speed is 110-320 r/min;

d, closing nitrogen, adding the nano silicon slurry into the mixture obtained in the step C, wherein the solvent is alcohol, the solid content is 6-10%, the mass of silicon is 6kg,

e: adding solid glucose accounting for 5-15% of the mass of the silicon and graphite into the mixture obtained in the step D, introducing nitrogen, rotating at the speed of 110-320 r/min, and stirring for 2-6 h;

f: heating and evaporating the mixture obtained in the step E to dryness, wherein the heating temperature is 120-260 ℃, and the stirring speed is 110-320 r/min;

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

and H, sieving the material precursor obtained in the step F with a 300-mesh sieve to obtain the silicon-carbon negative electrode material for the lithium ion battery.

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