CN-116565168-B - Phosphorus-silver-silicon co-doped hard carbon composite material and preparation method thereof

CN116565168BCN 116565168 BCN116565168 BCN 116565168BCN-116565168-B

Abstract

The invention discloses a phosphorus-silver-silicon co-doped hard carbon composite material and a preparation method thereof, wherein the composite material has a core-shell structure, and an inner core is composed of silver, phosphorus and silicon doped amorphous carbon, an outer shell amorphous carbon and a lithium salt compound thereof. The preparation method comprises the steps of ball milling nano silicon, red phosphorus and silver powder, vacuum drying to obtain a silver/phosphorus/silicon composite material, dissolving resin in an organic solvent, adding the silver/phosphorus/silicon composite material, performing ultrasonic dispersion, performing spray drying to obtain a precursor material, transferring the precursor material into a tubular furnace, carbonizing in an inert atmosphere to obtain an amorphous carbon coated silver/phosphorus/silicon composite material, mixing and pressing the amorphous carbon coated silver/phosphorus/silicon composite material and a binder to form a block structure, taking the block structure as a working electrode, depositing lithium salt on the surface of the working electrode by an electrochemical deposition method, and vacuum drying and carbonizing to obtain the amorphous carbon coated silver/phosphorus/silicon composite material. The ionic conductivity and the first efficiency thereof of the invention and improves the cycle performance.

Inventors

ZHANG QIAN

Assignees

晖阳(贵州)新能源材料有限公司

Dates

Publication Date: 20260512
Application Date: 20230522

Claims (4)

1. A preparation method of a phosphorus-silver-silicon co-doped hard carbon composite material comprises the following steps: Step S1, adding micrometer silicon into a high-energy ball mill according to the mass ratio of silver powder to red phosphorus, namely nanometer silicon=1-5:10:1-5, grinding for 12-72 hours to obtain nanometer silicon with the particle size of 100-200nm, continuously adding red phosphorus, grinding the silver powder into the ball mill for 12-72 hours, and carrying out vacuum drying at 80 ℃ for 24 hours to obtain a silver/phosphorus/silicon composite material; Step S2, dissolving resin in an organic solvent according to the mass ratio of the organic solvent to the silver/phosphorus/silicon composite material=100:500-1500:1-10, adding the silver/phosphorus/silicon composite material, performing ultrasonic dispersion, wherein the ultrasonic frequency is 25KHz, the dispersion speed is 5000r/min, the dispersion time is 60min, the air inlet temperature is 200 ℃ and the air flow is 60mL/min, the air outlet temperature is 80 ℃, the precursor material is obtained, transferring the precursor material into a tube furnace, and carbonizing for 1-6h at 600-1000 ℃ in an inert atmosphere, thereby obtaining the amorphous carbon coated silver/phosphorus/silicon composite material; And S3, according to the mass ratio of amorphous carbon to coated silver/phosphorus/silicon composite material, namely binder=100:1-10, mixing and pressing the amorphous carbon coated silver/phosphorus/silicon composite material and the binder into a block structure, taking a saturated calomel electrode as a working electrode, simultaneously configuring 0.1mol/L of lithium difluorodioxalate phosphate ethylene carbonate, depositing lithium salt on the surface of the working electrode by an electrochemical deposition method, washing 1-5 times by adopting 1mol/L of hydrochloric acid after the deposition time is 10-120min, drying in vacuum at 80 ℃ for 24h, and carbonizing at 700-1000 ℃ for 1-6h to obtain the phosphorus-silver-silicon co-doped hard carbon composite material.
2. The preparation method of the phosphorus-silver-silicon co-doped hard carbon composite material according to claim 1, wherein in the step S2, the resin is one of phenolic resin, furfural resin or epoxy resin, and the organic solvent is one of chloroform, toluene, acetone or xylene.
3. The preparation method of the phosphorus-silver-silicon co-doped hard carbon composite material according to claim 1, wherein the binder in the step S2 is one of polyvinyl alcohol, polyacrylic acid, polytetrafluoroethylene, polyvinylidene fluoride or sodium carboxymethyl cellulose.
4. The preparation method of the phosphorus-silver-silicon co-doped hard carbon composite material according to claim 1, wherein the electrochemical deposition method in the step S3 is one of cyclic voltammetry, constant voltage method, constant current method or pulse method, the parameters of the cyclic voltammetry are-2V, 0.5-5mV/S, the parameters of the constant voltage method are 2V, and the constant current method is 1-10mA/cm 2 .

Description

Phosphorus-silver-silicon co-doped hard carbon composite material and preparation method thereof Technical Field The invention belongs to the field of preparation of lithium ion battery materials, in particular to a phosphorus-silver-silicon co-doped hard carbon composite material and relates to a preparation method of the phosphorus-silver-silicon co-doped hard carbon composite material. Background The hard carbon material is applied to 48V, HEV, sodium ion battery and other fields by the advantages of zero expansion, excellent low-temperature performance, good quick charge performance and the like. However, the high specific surface area causes the first efficiency of the material to be lower (80%) because the hard carbon is of a porous structure, and the specific capacity is about 300mAh/g and is far lower than 355mAh/g of graphite and 1600mAh/g of silicon oxide. In order to solve the problem, at present, hard carbon materials are doped and hole forming means thereof are used for processing, for example, phosphorus, nitrogen and silicon are doped, the energy density of the doped materials is improved, but the voltage platform is increased due to the increase of impedance, so that the impedance of the materials is required to be reduced by doping some metal elements with high electronic conductivity to improve the power performance. Disclosure of Invention The invention aims to overcome the defects and provide the phosphorus-silver-silicon co-doped hard carbon composite material with ion conductivity and first efficiency and improved cycle performance. The invention further aims at providing a preparation method of the phosphorus-silver-silicon co-doped hard carbon composite material. The phosphorus-silver-silicon co-doped hard carbon composite material has a core-shell structure, wherein the core is silver, phosphorus and silicon doped hard carbon, the shell is composed of amorphous carbon and lithium salt compound, and the shell accounts for 1-10wt% calculated by 100% of the composite material by mass. The invention discloses a preparation method of a phosphorus-silver-silicon co-doped hard carbon composite material, which comprises the following steps: Step S1, adding micrometer silicon into a high-energy ball mill according to the mass ratio of silver powder to red phosphorus, namely nanometer silicon=1-5:10:1-5, grinding for 12-72 hours to obtain nanometer silicon with the particle size of 100-200nm, continuously adding red phosphorus, grinding the silver powder into the ball mill for 12-72 hours, and carrying out vacuum drying at 80 ℃ for 24 hours to obtain a silver/phosphorus/silicon composite material; Step S2, dissolving resin in an organic solvent according to the mass ratio of the resin to the silver/phosphorus/silicon composite material=100:500-1500:1-10, adding the silver/phosphorus/silicon composite material, performing ultrasonic dispersion (the ultrasonic frequency is 25KHz, the dispersion speed is 5000r/min, and the dispersion time is 60 min), obtaining a precursor material through spray drying (the air inlet temperature is 200 ℃, the flow is 60mL/min, and the air outlet temperature is 80 ℃), transferring the precursor material into a tube furnace, and carbonizing for 1-6h at the temperature of 600-1000 ℃ under inert atmosphere to obtain the amorphous carbon coated silver/phosphorus/silicon composite material; And S3, according to the mass ratio of amorphous carbon to coated silver/phosphorus/silicon composite material, namely binder=100:1-10, mixing and pressing the amorphous carbon coated silver/phosphorus/silicon composite material and the binder into a block structure, taking a saturated calomel electrode as a working electrode, simultaneously configuring 0.1mol/L of lithium difluorodioxalate phosphate ethylene carbonate, depositing lithium salt on the surface of the working electrode by an electrochemical deposition method, washing 1-5 times by adopting 1mol/L of hydrochloric acid after the deposition time is 10-120min, drying in vacuum at 80 ℃ for 24h, and carbonizing at 700-1000 ℃ for 1-6h to obtain the phosphorus-silver-silicon co-doped hard carbon composite material. The preparation method of the phosphorus-silver-silicon co-doped hard carbon composite material comprises the step S2, wherein resin is one of phenolic resin, furfural resin or epoxy resin, and organic solvent is one of chloroform, toluene, acetone or xylene. The preparation method of the phosphorus-silver-silicon co-doped hard carbon composite material comprises the step S2, wherein the binder is one of polyvinyl alcohol, polyacrylic acid, polytetrafluoroethylene, polyvinylidene fluoride or sodium carboxymethyl cellulose. The preparation method of the phosphorus-silver-silicon co-doped hard carbon composite material comprises the step S3, wherein the electrochemical deposition method is one of a cyclic voltammetry method, a constant voltage method, a constant current method or a pulse method, the parameters of the c