CN-118306976-B - Preparation method of double-layer coated silicon-carbon composite material

CN118306976BCN 118306976 BCN118306976 BCN 118306976BCN-118306976-B

Abstract

The invention discloses a preparation method of a double-layer coated silicon-carbon composite material, which comprises the steps of uniformly mixing acid-based resin and an organic base pore-forming agent, adding the mixture into carboxymethyl cellulose lithium, uniformly dispersing, spray drying, transferring the obtained material into a tubular furnace for carbonization, naturally cooling to room temperature to obtain lithium doped porous carbon, adding niobium salt, titanium salt and liquid silane into an organic solvent to prepare a solution with the concentration of 1-10wt%, uniformly dispersing, adding lithium doped porous carbon, uniformly dispersing, spray drying, transferring into the tubular furnace for sintering to obtain a titanium niobate coated silicon-carbon composite material, transferring into the tubular furnace, and depositing amorphous carbon on the surface of the titanium niobate coated silicon-carbon composite material to obtain the double-layer coated silicon-carbon composite material. The material obtained by the invention can improve the first efficiency, the quick charge performance and the expansion reduction.

Inventors

HU HAIPING
HU HAIJUN
HU WENLIANG
SUN JUN
GAO ZHUAN
Zha Xianyan
LI XIAOMAN
LI CHANGKUN

Assignees

晖阳(贵州)新能源材料有限公司

Dates

Publication Date: 20260512
Application Date: 20240428

Claims (4)

1. The preparation method of the double-layer coated silicon-carbon composite material comprises the following steps: Step S1, uniformly mixing resin and an organic base pore-forming agent according to the mass ratio of resin to organic base pore-forming agent, namely carboxymethyl cellulose lithium=100:1-10:1-5, adding the mixture into carboxymethyl cellulose lithium solution, uniformly dispersing, spray-drying the mixture for 0.5h at an inlet temperature of 220 ℃ and an outlet temperature of 80 ℃ at a flow rate of 1kg/h, transferring the obtained material into a tube furnace, carbonizing the material for 1-6h at the temperature of 700-900 ℃, then heating the material to 1100 ℃, introducing water vapor for 2-12h according to the flow rate of 500-1000ml/min, and naturally cooling the material to room temperature to obtain lithium doped porous carbon; step S2, adding niobium salt, titanium salt and liquid silane into an organic solvent according to the mass ratio of niobium salt to titanium salt, lithium doped porous carbon=5-20:100-300:100 to prepare a solution with the weight percent of 1-10%, uniformly dispersing, adding lithium doped porous carbon, uniformly dispersing, spray drying for 0.5h at the inlet temperature of 220 ℃ and the outlet temperature of 80 ℃ at the flow rate of 1kg/h, transferring the obtained material into a tubular furnace, introducing air in an inert gas discharge pipe, and heating to 300-500 ℃ to sinter for 1-6h to obtain the titanium niobate coated silicon carbon composite material; The niobium salt is one of niobium oxalate, niobium n-propoxide, niobium isopropoxide, niobium amyl alcohol or niobium phenol; the titanium salt is one of ethyl titanate, tetraethyl titanate, propyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetraisopropoxytitanium or tetraisopropoxytitanium; the organic solvent is one of methyl ether, diethyl ether, dipropyl ether, ethyl butyl ether, dibutyl ether or dipentyl ether; Niobium salt: titanium salt molar ratio = 1:1-2; Step S3, transferring the titanium niobate coated silicon carbon composite material into a tube furnace, firstly introducing air in an inert gas discharge tube, then heating to 500-800 ℃, introducing carbon source gas for 1-6h according to the flow rate of 50-500ml/min, and depositing amorphous carbon on the surface of the titanium niobate coated silicon carbon composite material to obtain a double-layer coated silicon carbon composite material; wherein the resin in the step S1 is one of diallyl isophthalate resin, acrylic resin, alkyd resin, fumaric resin or malic resin.
2. The method for preparing a double-layer coated silicon-carbon composite material as claimed in claim 1, wherein the organic base pore-forming agent in the step S1 is one of dimethyl isopropylamine, 1-methylpyrrolidine, triethylamine, 1-methylpiperidine or 4-methylmorpholine.
3. The method for preparing a double-layer coated silicon-carbon composite material as claimed in claim 1, wherein: the liquid silane in the step S2 is one of tetraethoxysilane, tetramethyl divinyl disiloxane, triethyl silane, trimethyl chlorosilane, triphenyl chlorosilane or hexamethyldisiloxane.
4. The method of claim 1, wherein the carbon source gas in the step S3 is one of methane, ethane, ethylene, acetylene or propyne.

Description

Preparation method of double-layer coated silicon-carbon composite material Technical Field The invention belongs to the field of lithium ion battery materials, and particularly relates to a preparation method of a double-layer coated silicon-carbon composite material. Background The novel silicon-carbon negative electrode material has the advantages of high specific capacity (1800-2000 mAh/g), high first efficiency (90-92%), low full-charge expansion, excellent cycle performance, low cost and the like, and becomes the first choice material of the lithium ion battery with high energy density. However, as the novel silicon-carbon material is composed of porous carbon and nano silicon deposited in pores, the powder resistance of the material is larger, the quick charge performance of the material is reduced, meanwhile, the expansion of a pole piece is high in the charge and discharge process, the expansion of a battery module is larger, and potential safety hazards are brought. Therefore, doping, cladding, and interfacial modification of the silicon-carbon material are required to reduce the resistance of the material and to reduce expansion. Disclosure of Invention The invention aims to overcome the defects and provide a preparation method of a double-layer coated silicon-carbon composite material, which can improve the first efficiency, quick charge performance and reduce expansion. The invention discloses a preparation method of a double-layer coated silicon-carbon composite material, which comprises the following steps: Step S1, according to the mass ratio of acid-base resin to organic base pore-forming agent, namely carboxymethyl cellulose lithium=100:1-10:1-5, uniformly mixing the acid-base resin and the organic base pore-forming agent, then adding the mixture into carboxymethyl cellulose lithium solution, uniformly dispersing, spray-drying the mixture for 0.5h at an inlet temperature of 220 ℃ and an outlet temperature of 80 ℃ at a flow rate of 1kg/h, transferring the obtained material into a tubular furnace, carbonizing the material for 1-6h at the temperature of 700-900 ℃, then heating the material to 1100 ℃, introducing water vapor for 2-12h according to the flow rate of 500-1000ml/min, and naturally cooling the material to room temperature to obtain lithium doped porous carbon; Step S2, adding niobium salt, titanium salt and liquid silane into an organic solvent according to the mass ratio (niobium salt and titanium salt) of lithium doped porous carbon=5-20:100-300:100 to prepare a solution with the weight percent of 1-10%, uniformly dispersing, adding lithium doped porous carbon, uniformly dispersing, spray-drying at the inlet temperature of 220 ℃ and the outlet temperature of 80 ℃ at the flow rate of 1kg/h for 0.5h, transferring the obtained material into a tubular furnace, introducing air in an inert gas discharge pipe, heating to 300-500 ℃ and sintering for 1-6h to obtain the titanium niobate coated silicon carbon composite material; The niobium salt is one of niobium oxalate, niobium n-propoxide, niobium isopropoxide, niobium amyl alcohol or niobium phenol; the titanium salt is one of ethyl titanate, tetraethyl titanate, propyl titanate, tetrapropyl titanate, tetrabutyl titanate, tetraisopropoxytitanium or tetraisopropoxytitanium; the organic solvent is one of methyl ether, diethyl ether, dipropyl ether, ethyl butyl ether, dibutyl ether or dipentyl ether; Niobium salt: titanium salt molar ratio = 1:1-2; And S3, transferring the titanium niobate coated silicon carbon composite material into a tube furnace, firstly introducing air in an inert gas discharge tube, then heating to 500-800 ℃, introducing carbon source gas for 1-6h according to the flow rate of 50-500ml/min, and depositing amorphous carbon on the surface of the titanium niobate coated silicon carbon composite material to obtain the double-layer coated silicon carbon composite material. The preparation method of the double-layer coated silicon-carbon composite material comprises the step S1, wherein the acid-based resin is one of diallyl isophthalate resin, acrylic resin, alkyd resin, fumaric resin or malic resin. The preparation method of the double-layer coated silicon-carbon composite material comprises the step S1, wherein the organic base pore-forming agent is one of dimethyl isopropylamine, 1-methylpyrrolidine, triethylamine, 1-methylpiperidine or 4-methylmorpholine. The preparation method of the double-layer coated silicon-carbon composite material comprises the step S2, wherein the liquid silane is one of tetraethoxysilane, tetramethyl divinyl disiloxane, triethylsilane, trimethylchlorosilane, triphenylchlorosilane or hexamethyldisiloxane. The preparation method of the double-layer coated silicon-carbon composite material comprises the step S3, wherein the carbon source gas is one of methane, ethane, ethylene, acetylene or propyne. Compared with the prior art, the preparation method has the advantages that the acid-based resin