CN-122000315-A - Preparation method of porous silicon-carbon anode material suitable for vapor deposition

Abstract

The invention discloses a preparation method of a gas-phase porous silicon-carbon anode material, which comprises the steps of (1) depositing silane gas and carbon source gas in porous carbon through a fluidized bed/rotary kiln equipment gas phase deposition process to form a CVD porous silicon-carbon material, (2) carrying out low-temperature ozone pretreatment on the obtained CVD silicon-carbon material, and (3) carrying out ALD atomic layer deposition on the CVD silicon-carbon material subjected to the ozone pretreatment to form a nano-scale metal oxide coating on the surface of the material. The ozone treatment process method and the ALD technology are suitable for optimizing artificial coating layers of various CVD gas-phase silicon-carbon materials with various initial surface carbon layers, can realize uniform and stable modification effects in batches, and have stability and positive effects in the aspects of initial capacity, initial effect and volume expansion inhibition of the materials. The method has obvious secondary coating effect on CVD silicon carbon, is suitable for batch preparation of materials, can achieve obvious optimization effect on electrochemical performance of the materials, and is simple, convenient and efficient.

Inventors

• LI ZIWEI
• LU ZHENBAO
• WANG XIAOWEI

Assignees

• 内蒙古翔福新能源有限责任公司
• 包头旭阳硅碳科技有限公司

Dates

Publication Date

20260508

Application Date

20251027

Claims (5)

1. 1. The preparation method of the gas-phase porous silicon-carbon anode material comprises the following steps: (1) Depositing silane gas and carbon source gas in porous carbon through a fluidized bed/rotary kiln equipment vapor deposition process to form a CVD porous silicon-carbon material; (2) Carrying out low-temperature ozone pretreatment on the obtained CVD silicon-carbon material; (3) And performing ALD atomic layer deposition on the CVD silicon-carbon material subjected to ozone pretreatment to form a nanoscale metal oxide coating layer on the material surface.
2. 2. The method according to claim 1, wherein, Preferably, in the step (1), the step of depositing silicon and coating carbon of the rotary kiln equipment generally comprises the steps of placing porous carbon, introducing nitrogen at normal temperature for replacement, heating to 420 ℃, introducing silane gas for nano silicon deposition, heating to 500 ℃, replacing and introducing acetylene gas for surface preliminary carbon coating, wherein the step of depositing silicon and coating carbon of the fluidized bed equipment generally comprises the steps of placing porous carbon, introducing nitrogen at normal temperature for half an hour, starting heating to 420 ℃ and continuously introducing nitrogen for 2 hours, introducing silane gas for 2 hours at 420 ℃, continuously introducing nitrogen, heating to 500 ℃, and introducing acetylene gas for 4 hours for surface preliminary carbon coating; Preferably, in step (1), the porous carbon substrate comprises a biomass substrate, a resin-based substrate or a pitch-based substrate porous carbon; Preferably, in step (1), the carbon source gas is selected from one or more different carbon-containing gases of methane, ethylene, acetylene, propylene, toluene.
3. 3. The method according to claim 1, wherein, Preferably, in the step (2), the ozone treatment method for the CVD silicon-carbon material is that the material is put into an ALD device and ozone gas with nitrogen as carrier gas is directly or pulsed; preferably, in step (2), the ozone pretreatment temperature for the CVD silicon carbon material is 200 degrees or less; preferably, in step (2), the ozone pretreatment time for the CVD silicon carbon material is 10s to 30min.
4. 4. The method according to claim 1, wherein, Preferably, in step (3), ALD atomic layer deposition is performed on the pretreated CVD silicon carbon, the cladding layer comprising one or more of alumina, titania, zinc oxide, ceria or zirconia; preferably, in the step (3), ALD atomic layer deposition is performed on the CVD silicon carbon after the pretreatment, the raw material of the metal oxide deposition coating layer is organic metal vapor containing the corresponding metal element, and the oxygen source is water vapor or ozone; preferably, in step (3), the ALD deposition process is a pulsed deposition, with a reactant gas source pulse time of 0.01s-3s; preferably, in step (3), the ALD deposition process is a pulsed deposition, the reactant gas source pulsed temperature being in the range of 50 degrees to 500 degrees; Preferably, in step (3), the ALD deposition process is a pulsed deposition, with a number of pulse cycles ranging from 5 to 500.
5. 5. A gas-phase porous silicon-carbon anode material prepared by the preparation method according to any one of claims 1 to 4, wherein the gas-phase porous silicon-carbon anode material has a first charge gram capacity of not less than 1600 mAh/g, a first coulombic efficiency of not less than 88%, and a pole piece full-charge expansion rate of not more than 60% after battery testing.

Description

Preparation method of porous silicon-carbon anode material suitable for vapor deposition Technical Field The invention relates to the field of battery materials, in particular to the field of preparation and processing of lithium battery silicon-carbon negative electrode materials, and particularly relates to an atomic layer deposition coating technology of a gas-phase porous silicon-carbon negative electrode material. Background The silicon-carbon negative electrode material of the lithium ion battery is a key material for realizing capacity improvement of the lithium ion battery, but silicon has huge volume change in the process of electrochemical lithium intercalation and deintercalation, and mechanical crushing and electrical contact failure of the material are easily caused. In addition, silicon itself is a semiconductor material, and as the size increases, the conductivity decreases, causing an increase in polarization. The CVD (chemical vapor deposition) porous silicon-carbon anode is a novel silicon-carbon anode material in recent years, and is prepared by using raw materials such as porous carbon, silane gas, carbon source gas and the like, silane gas is deposited and adsorbed in porous carbon substrate pore channels to form nano silicon by controlling key process parameters such as reaction temperature, air pressure, gas flow rate and the like, and carbon source gas is deposited on the surface through vapor phase pyrolysis to coat a layer of carbon. Finally, the method meets the index requirements of the product such as the granularity, the specific surface, the powder resistance and the like, and realizes the high first coulombic efficiency and the high specific capacity of the cathode silicon-carbon in the battery. The carbon layer coating on the surface of the CVD silicon carbon can keep the chemical stability of silicon to a certain extent, improve the conductivity and inhibit the side reaction of electrolyte. However, CVD porous silicon carbon materials are difficult to sufficiently suppress the volume change of silicon, and with charge and discharge cycles, the surface-coated carbon layer has insufficient structural strength and still fails to fracture. Meanwhile, the density of the deposited carbon layer is limited, negative ions in the electrolyte and silicon are difficult to block to generate side reactions, and the capacity gradually declines. At a more critical point in the CVD process, the vapor deposited carbon source gas, if not subject to specific raw materials and process control, is prone to insufficient cracking during the deposition process, and locally forms tar byproducts to cover the surface of the silicon carbon material. Such by-products are inherently less conductive and result in increased powder resistance. ALD (atomic layer deposition) processes have been widely developed in the semiconductor field and have been used in recent years in the field of lithium batteries by alternately feeding different reaction precursors into a reaction chamber in the form of gas pulses. ALD has significant advantages over conventional deposition processes in terms of film uniformity, step coverage, and thickness control. The ALD technology is used for further coating the surface of the metal oxide on the silicon-carbon material, so that the even, compact, high-strength and thin-thickness artificial protection film can be further constructed, the volume expansion of the silicon material in the lithium intercalation process is obviously inhibited, and the side reaction caused by electrolyte permeation is reduced. Patent CN118763171A utilizes an atomic layer deposited titanium dioxide nano film to cover the surface of nitrogen doped microporous carbon derived from MOFs to construct artificial SEI, but the method is only focused on the effects of a silicon-carbon composite material synthesized by a liquid phase method and a titanium dioxide coating layer, and does not explore the effects of different raw materials/metal oxide components in an ALD branching technology or the popularization of the ALD technology to CVD vapor deposition of silicon-carbon materials. The combination of ALD technology and CVD silicon carbon has recently attracted attention. The patent CN119954159A grows a first metal oxide on the surface of a carbon substrate material by using an ALD atomic layer deposition method and then reduces the first metal oxide into nano points containing metal elements, and the nano points are used for assisting the deposition of gas phase silane and coating a carbon layer on the surface of a silicon nanowire based on a CVD cracking process. However, the method focuses on the modification regulation of ALD on a carbon substrate, and the surface coating layer of the material is still a carbon layer with the problem of the limitation. In fact, due to the problem of the tar byproduct during the CVD silicon carbon production process, local reaction and consumption of the active gas source mate