CN-121983539-A - Preparation method of aluminum-nitrogen co-doped modified silicon-carbon anode material and lithium ion battery

CN121983539ACN 121983539 ACN121983539 ACN 121983539ACN-121983539-A

Abstract

The preparation method of the aluminum-nitrogen co-doped silicon-carbon negative electrode material comprises the following steps of obtaining a porous carbon substrate, synchronously depositing silicon on the pores and the surfaces of the porous carbon substrate through chemical vapor deposition, doping aluminum and nitrogen, and obtaining a co-doped intermediate; the co-doped intermediate is mixed with a carbon source and heat treated to form a dense amorphous carbon coating. The aluminum-nitrogen co-doping can cooperatively regulate the Fermi level of silicon, the conductivity and the multiplying power performance of the material are improved, the lattice expansion caused by aluminum doping enhances the tolerance of silicon to volume change, the SiN x phase formed by nitrogen doping strengthens the interface binding force and jointly improves the structural stability, the surface SiN x phase and the carbon coating layer are favorable for forming a stable SEI film, and the consumption of active lithium and electrolyte is reduced, so that the cycle performance is improved.

Inventors

ZHONG HUA
LIAO XINGQUN

Assignees

深圳市豪鹏科技股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260119

Claims (10)

1. The preparation method of the aluminum-nitrogen co-doped modified silicon-carbon anode material is characterized by comprising the following steps of: Obtaining a porous carbon substrate; placing the porous carbon substrate into a chemical vapor deposition reactor, introducing silicon source gas, aluminum source gas, nitrogen source gas and inert gas carrier gas, performing silicon deposition on the pores and the surfaces of the porous carbon substrate, and performing synchronous doping of aluminum and nitrogen to obtain a co-doped intermediate; And uniformly mixing the co-doped intermediate with a carbon source, and performing high-temperature heat treatment in an inert atmosphere to form a compact amorphous carbon coating layer so as to obtain the aluminum-nitrogen co-doped modified silicon-carbon anode material.
2. The method for preparing an aluminum nitrogen co-doped modified silicon carbon negative electrode material according to claim 1, wherein a porous carbon substrate is obtained, comprising the steps of: phenolic resin is used as a carbon precursor, a curing agent is added, and the mixture is uniformly mixed and heated for curing to obtain cured resin; Carrying out high-temperature carbonization treatment on the cured resin under the protection of inert atmosphere to obtain a carbonized product; Uniformly mixing the carbonized product and an alkali activator in proportion, and performing high-temperature activation pore-forming treatment under the protection of inert atmosphere to obtain an activated product; and (3) washing the activated product with acid, washing with water to neutrality, and drying to obtain the porous carbon substrate.
3. The method for preparing an aluminum-nitrogen co-doped modified silicon-carbon anode material according to claim 1, wherein a porous carbon substrate is placed in a reactor, silicon source gas, aluminum source gas, nitrogen source gas and inert gas carrier gas are introduced to deposit silicon on the pores and the surface of the porous carbon substrate and to synchronously dope aluminum and nitrogen, so as to obtain a co-doped intermediate, and the method comprises the following steps of; placing the porous carbon substrate in a chemical vapor deposition reactor; heating the chemical vapor deposition reactor; Introducing a silicon source gas, an aluminum source gas and a nitrogen source gas into the chemical vapor deposition reactor, controlling the temperature of the chemical vapor deposition reactor, wherein the pressure of the chemical vapor deposition reactor is 200Pa-800Pa, the reaction temperature in the chemical vapor deposition reactor is 550-680 ℃, and the silicon source gas, the aluminum source gas and the nitrogen source gas generate chemical vapor deposition reaction on the pores and the surfaces of the porous carbon substrate to perform silicon deposition and aluminum and nitrogen element synchronous doping; And after the reaction is finished, cooling under the atmosphere of inert gas carrier gas to obtain the co-doped intermediate.
4. The method for preparing an aluminum-nitrogen co-doped modified silicon-carbon anode material according to claim 1, wherein when a silicon source gas, an aluminum source gas and a nitrogen source gas are simultaneously introduced into the chemical vapor deposition reactor, the molar flow ratio of the silicon source gas, the aluminum source gas and the nitrogen source gas is 20-80:1:1.6-2.5.
5. The method for producing an aluminum-nitrogen co-doped modified silicon-carbon negative electrode material according to claim 4, wherein the co-doped intermediate has an atomic doping amount of aluminum element of 1.2at.% to 2.0at.% and an atomic doping amount of nitrogen element of 2.5at.% to 3.8at.%.
6. The method for preparing an aluminum nitrogen co-doped modified silicon carbon anode material according to claim 1, wherein the silicon source gas is silane.
7. The method for producing an aluminum-nitrogen co-doped modified silicon-carbon negative electrode material according to claim 1, wherein the aluminum source gas is at least one of trimethylaluminum, triethylaluminum, dimethylaluminum hydride, aluminum chloride, and tri (t-butoxy) aluminum.
8. The method for preparing the aluminum-nitrogen co-doped modified silicon-carbon anode material according to claim 1, wherein the nitrogen source gas is at least one of ammonia gas, hydrazine, tert-butylamine and trimethylamine silicon.
9. The method for preparing an aluminum nitrogen co-doped modified silicon carbon negative electrode material according to claim 1, wherein the co-doped intermediate is uniformly mixed with a carbon source, and the mixture is subjected to high temperature heat treatment in an inert atmosphere to form a dense amorphous carbon coating layer, comprising the following steps: Acetylene and propane gases are led into a reaction chamber to carry out deposition coating on the co-doped intermediate; And carrying out high-temperature heat treatment at 700-1000 ℃ in an inert atmosphere to form a compact amorphous carbon layer on the surface of the co-doped intermediate, so as to obtain the aluminum-nitrogen co-doped modified silicon-carbon anode material.
10. A lithium ion battery, which is characterized by comprising a positive plate, a diaphragm and a silicon-carbon negative electrode material obtained by adopting the preparation method of the aluminum-nitrogen co-doped modified silicon-carbon negative electrode material in any one of claims 1-9, wherein the silicon-carbon negative electrode material is used for preparing a silicon-carbon negative electrode plate, and the positive plate, the diaphragm and the silicon-carbon negative electrode plate are sequentially stacked and packaged to obtain the lithium ion battery.

Description

Preparation method of aluminum-nitrogen co-doped modified silicon-carbon anode material and lithium ion battery Technical Field The disclosure relates to the technical field of lithium ion batteries, in particular to a preparation method of an aluminum-nitrogen co-doped modified silicon-carbon anode material and a lithium ion battery. Background The silicon-carbon composite material is a key negative electrode material of the next generation of high-energy density lithium ion batteries. However, the huge volume change of silicon in the lithiation and delithiation process leads to the structural damage of the electrode and the drastic attenuation of the cycle performance, and the low intrinsic conductivity of the silicon-carbon composite material limits the fast charging capability thereof. The prior art mostly adopts carbon coating, nanocrystallization and element doping (such as boron and phosphorus) to improve the performance. However, these methods either have limited contribution to buffer volume expansion or can only enhance conductivity, single enhancement of negative electrode material function; According to the existing preparation method of the carbon-coated silicon anode material assisted by the boron-nitrogen doped polymer, nano silicon powder, a nitrogen-containing polymer monomer, a boron-containing compound and an initiator are weighed as solid raw materials, temperature reaction is controlled in a concentrated acid solution, a nitrogen-containing polymer-silicon precursor is obtained through filtration and drying, and the precursor is calcined in protective atmospheres at different temperatures to obtain the boron-nitrogen doped carbon-coated silicon anode material. The scheme has limited contribution to buffer volume expansion, improves conductivity, and has single function of improving the cathode material. Disclosure of Invention The invention aims to overcome the defects in the prior art and provide a preparation method of an aluminum-nitrogen co-doped modified silicon-carbon negative electrode material and a lithium ion battery, wherein the aluminum-nitrogen co-doped modified silicon-carbon negative electrode material has the advantages of improving conductivity and quick charge rate performance and strengthening silicon-carbon interface binding force. The aim of the disclosure is achieved by the following technical scheme: The preparation method of the aluminum-nitrogen co-doped modified silicon-carbon anode material comprises the following steps: Obtaining a porous carbon substrate; placing the porous carbon substrate into a chemical vapor deposition reactor, introducing silicon source gas, aluminum source gas, nitrogen source gas and inert gas carrier gas, performing silicon deposition on the pores and the surfaces of the porous carbon substrate, and performing synchronous doping of aluminum and nitrogen to obtain a co-doped intermediate; And uniformly mixing the co-doped intermediate with a carbon source, and performing high-temperature heat treatment in an inert atmosphere to form a compact amorphous carbon coating layer so as to obtain the aluminum-nitrogen co-doped modified silicon-carbon anode material. In one embodiment, a porous carbon substrate is obtained comprising the steps of: phenolic resin is used as a carbon precursor, a curing agent is added, and the mixture is uniformly mixed and heated for curing to obtain cured resin; Carrying out high-temperature carbonization treatment on the cured resin under the protection of inert atmosphere to obtain a carbonized product; Uniformly mixing the carbonized product and an alkali activator in proportion, and performing high-temperature activation pore-forming treatment under the protection of inert atmosphere to obtain an activated product; and (3) washing the activated product with acid, washing with water to neutrality, and drying to obtain the porous carbon substrate. In one embodiment, a porous carbon substrate is placed in a reactor, and silicon source gas, aluminum source gas, nitrogen source gas and inert gas carrier gas are introduced to deposit silicon and synchronously dope aluminum and nitrogen on the pores and the surfaces of the porous carbon substrate, so as to obtain a co-doped intermediate, which comprises the following steps of; placing the porous carbon substrate in a chemical vapor deposition reactor; heating the chemical vapor deposition reactor; Introducing a silicon source gas, an aluminum source gas and a nitrogen source gas into the chemical vapor deposition reactor, controlling the temperature of the chemical vapor deposition reactor, wherein the pressure of the chemical vapor deposition reactor is 200Pa-800Pa, the reaction temperature in the chemical vapor deposition reactor is 550-680 ℃, and the silicon source gas, the aluminum source gas and the nitrogen source gas generate chemical vapor deposition reaction on the pores and the surfaces of the porous carbon substrate to perform silicon deposition and al