Patent Application
20240372075
The present disclosure relates to the technical field of materials, in particular, to a novel composite material for a secondary lithium battery, a preparation method therefor and an application thereof.
In recent years, due to the rapid advancement of electronic technology and the information industry, the development prospect of lithium-ion batteries becomes increasingly vast. They have found widespread applications in portable devices such as mobile phones, notebook computers, and digital cameras. To keep up with the increasing demand for lithium-ion batteries with long cycle life, high energy density, and outstanding rate performance in electric vehicles and large energy storage systems, numerous researchers are actively investigating cost-effective and high-quality electrode materials.
Silicon has gained considerable interest among researchers as a potential negative electrode material due to its exceptional theoretical specific capacity (4200 mAh·g4). However, the lithiation process of silicon results in substantial volume expansion, leading to structural damage and an unstable solid electrolyte interface (SEI) film. Furthermore, the intrinsic electronic conductivity of silicon is poor, significantly impeding its electrochemical performance. These challenges pose significant barriers to the practical implementation of silicon-based negative electrodes.
Encapsulating silicon nanoparticles within a carbon material to create a C/Si composite material has emerged as a highly effective approach, which not only mitigates the volume expansion issues of silicon but also harnesses the advantages of both silicon (high capacity) and carbon (excellent conductivity and cycle stability). However, nano-materials have a high specific surface energy, which makes them prone to agglomeration and difficult to uniformly disperse within a carbon matrix. As a consequence, the electrochemical performance improvement is compromised. Although CN 106299277A discloses a silicon-carbon composite negative electrode material for lithium-ion batteries, its use of mechanical mixing fails to achieve a desired level of mixing between silicon and carbon materials, consequently offering limited enhancements in cycle performance.
The embodiments of the present disclosure provide a novel composite material for a secondary lithium battery, a preparation method therefor and an application thereof. By fully mixing and co-depositing a silicon source and a carbon source, carbon atoms are uniformly embedded in a nano-silicon material at an atomic level. Compared with ordinary nano-silicon materials or silicon-carbon composite materials, this material exhibits enhanced structural stability and reduced volume expansion in a lithium dis-embedding process, having better cycle performance when utilized as a negative electrode in lithium batteries.
In a first aspect, an embodiment of the present disclosure provides a novel composite material for a secondary lithium battery, including: nano-silicon and carbon atoms, wherein the carbon atoms are uniformly distributed in the nano-silicon at an atomic level; the carbon atoms are bonded to silicon atoms to form amorphous Si—C bonds, and no SiC crystallization peak exists in an X-ray diffraction (XRD) energy spectrum;
Preferably, the novel composite material also contains oxygen, which is dispersed in the nano-silicon material or on a surface of the material, and a mass of the oxygen accounts for 0.1%-20% of the mass of the novel composite material.
Preferably, the novel composite material is of a monomer structure, or the novel composite material is deposited inside or on a surface of a matrix material; and the monomer structure includes nanoparticles or nanowires.
In a second aspect, an embodiment of the present disclosure provides a preparation method for the novel composite material for a secondary lithium battery described in the first aspect, including:
Preferably, the silicon source is silicon-containing vapor, specifically including one or more of monosilane, disilane, tetrafluorosilane, hexamethyldisilane and dimethylsiloxane;
In a third aspect, an embodiment of the present disclosure provides a negative plate including the novel composite material for the secondary lithium battery described in the first aspect.
In a fourth aspect, an embodiment of the present disclosure provides a lithium battery including the novel composite material for the secondary lithium battery described in the first aspect.
According to the novel composite material for the secondary lithium battery provided by the present disclosure, by fully mixing and co-depositing a silicon source and a carbon source, carbon atoms are uniformly embedded in a nano-silicon material at an atomic level. Compared with ordinary nano-silicon materials or silicon-carbon composite materials, this material exhibits enhanced structural stability and reduced volume expansion in a lithium dis-embedding process, having better cycle performance when utilized as a negative electrode in lithium batteries.
The technical solutions of the embodiments of the present disclosure will be described in further detail with reference to the drawings and embodiments.
The present disclosure will be further explained below by referring to drawings and specific embodiments, but it should be understood that these embodiments are only for more detailed explanation, and should not be construed as limiting the present disclosure in any way, that is, not intended to limit the scope of protection of the present disclosure.
A novel composite material for a secondary lithium battery provided by the present disclosure includes nano-silicon and carbon atoms, wherein the carbon atoms are uniformly distributed in the nano-silicon at an atomic level; the carbon atoms are bonded to silicon atoms to form amorphous Si—C bonds, and no SiC crystallization peak exists in an X-ray diffraction (XRD) energy spectrum;
In an alternative solution, the novel composite material also contains oxygen, which is dispersed in the nano-silicon material or on a surface of the material, and a mass of the oxygen accounts for 0.1%-20% of the mass of the novel composite material.
The novel composite material provided by the present disclosure is of a monomer structure, and the monomer structure includes nanoparticles or nanowires; or the novel composite material is deposited inside or on a surface of a matrix material.
The novel composite material for the secondary lithium battery provided by the present disclosure can be prepared by the preparation method shown in
Step 110, a silicon source, a carbon source, and a carrier gas are simultaneously introduced into a reaction vessel in proportion, and a temperature of the reaction vessel is controlled to be 450° C.-1000° C. and a reaction pressure is controlled to be 0.1 atm-10 atm.
Specifically, the silicon source is silicon-containing vapor, specifically including one or more of monosilane, disilane, tetrafluorosilane, hexamethyldisilane and dimethylsiloxane.
The carbon source includes one or more of acetylene, methane, propylene, ethylene, propane or ethanol.
The carrier gas includes one or more of hydrogen, nitrogen and argon.
Step 120, cooling is performed after the reaction is finished to obtain a novel composite material for a secondary lithium battery, or a product generated by the reaction is introduced into a cooling chamber during the reaction to obtain a novel composite material for a secondary lithium battery.
Specifically, reaction results can be controlled by removing the gas sources.
According to the novel composite material for the secondary lithium battery provided by the present disclosure, by fully mixing and co-depositing a silicon source and a carbon source, carbon atoms are uniformly embedded in a nano-silicon material at an atomic level. The novel composite material can be used for preparing negative plates that are applied to secondary lithium batteries such as lithium-ion batteries and solid-state lithium batteries. Compared with ordinary nano-silicon materials or silicon-carbon composite materials, this material exhibits enhanced structural stability and reduced volume expansion in a lithium dis-embedding process, having better cycle performance when utilized as a negative electrode in lithium batteries.
In order to better understand the technical solutions provided by the present disclosure, the specific process of preparing the novel composite material for the secondary lithium battery by the method provided in the above embodiment of the present disclosure, the method of its application in a secondary battery, and battery characteristics are described below with several specific examples.
A mixture of 1 L/min of silane, 1 L/min of methane and 1 L/min of argon is introduced into a deposition chamber of a fluidized bed device at 700° C. and 1 atm; and
It is tested, by a carbon-sulfur analyzer, that the carbon content of the novel composite material is 8%.
The obtained novel composite material is subjected to XRD testing to obtain an XRD pattern. The results are shown in
The novel composite material is subjected to 29Si spectrum solid-state NMR testing to obtain a 29Si NMR pattern, as shown by the curve in
A mixture of 1 L/min of silane, 0.2 L/min of methane and 1 L/min of argon is introduced into a deposition chamber of a fluidized bed device at 700° C. and 1 atm; and
It is tested, by a carbon-sulfur analyzer, that the carbon content of the novel composite material is 2%.
A mixture of 1 L/min of silane, 0.2 L/min of methane and 1 L/min of argon is introduced into a deposition chamber of a fluidized bed device at 700° C. and 1 atm, wherein a porous carbon material in a fluidized state is in the fluidized bed; and
The novel composite material is subjected to 29Si spectrum solid-state NMR testing to obtain a 29Si NMR pattern, as shown by the curve in
A mixture of 1 L/min of silane, 1 L/min of methane and 1 L/min of argon is introduced into a rotary furnace at 700° C. and 1 atm; and
It is tested, by a carbon-sulfur analyzer, that the carbon content of the novel composite material is 7%.
A mixture of 1 L/min of silane, 1 L/min of methane and 1 L/min of argon is introduced into a rotary furnace at 900° C. and 1 atm; and
It is tested, by a carbon-sulfur analyzer, that the carbon content of the novel composite material is 9%.
A mixture of 1 L/min of silane, 1 L/min of methane and 1 L/min of argon is introduced into a deposition chamber of a fluidized bed device at 700° C. and 2 atm; and
It is tested, by a carbon-sulfur analyzer, that the carbon content of the novel composite material is 10%.
A mixture of 1 L/min of silane, 1 L/min of acetylene and 1 L/min of argon is introduced into a deposition chamber of a fluidized bed device at 700° C. and 1 atm; and
It is tested, by a carbon-sulfur analyzer, that the carbon content of the novel composite material is 15%.
A mixture of 1 L/min of silane, 3 L/min of acetylene and 1 L/min of argon is introduced into a deposition chamber of a fluidized bed device at 700° C. and 1 atm; and
It is tested, by a carbon-sulfur analyzer, that the carbon content of the novel composite material is 35%.
A mixture of 1 L/min of silicon tetrafluoride, 1 L/min of methane and 1 L/min of argon is introduced into a deposition chamber of a fluidized bed device at 700° C. and 1 atm; and
It is tested, by a carbon-sulfur analyzer, that the carbon content of the novel composite material is 5%.
A mixture of 1 L/min of dimethyl siloxane, 1 L/min of methane and 1 L/min of argon is introduced into a deposition chamber of a fluidized bed device at 700° C. and 1 atm; and
It is tested, by a carbon-sulfur analyzer, that the carbon content of the novel composite material is 4%, and the oxygen content is 10%.
A mixture of 1 L/min of dimethyl siloxane, 1 L/min of methane and 1 L/min of hydrogen is introduced into a deposition chamber of a fluidized bed device at 700° C. and 1 atm; and
It is tested, by a carbon-sulfur analyzer, that the carbon content of the novel composite material is 8%.
In order to better illustrate the characteristics of the novel composite material of the invention, Comparative example 1 and Comparative example 2 are used for comparison.
A mixture of 1 L/min of silane and 1 L/min of argon is introduced into a deposition chamber of a fluidized bed device at 700° C. and 1 atm; and
It is tested, by a carbon-sulfur analyzer, that there is no carbon in the novel composite material.
The silicon-based material obtained in Comparative example 1 is subjected to gaseous-phase carbon coating with a carbon coating amount of 8%.
The novel composite materials obtained in the above embodiments and the materials obtained in the comparative examples are prepared into lithium button batteries, respectively, and then the capacity and initial efficiency are tested. The test results are listed in Table 1. In addition, the novel composite materials obtained in the above embodiments and the materials obtained in the comparative examples are compounded with commercial graphite in proportion into composite materials of 450 mAh/g, respectively, which are then assembled with lithium cobalt oxides to form button-type full cells; and the button-type full cells are made to cycle at 1 C/1 C to evaluate the cycle performance. Data are recorded in Table 1 for comparison.
By comparison, it can be seen that the uniform distribution of carbon atoms in the materials of various embodiments of the present disclosure can improve the cycle performance of the battery. With the increase of the flow rate of carbon source gas, the carbon content increases, and the monomer capacity and initial efficiency slightly decrease, but the cycle performance is obviously improved compared with Comparative examples 1 and 2. The silicon-based material of Embodiment 3 deposited in porous carbon can have better cycle performance. When the materials in Embodiments 10 and 11 contain oxygen, the initial efficiency is low, but the cycle performance is still relatively good. Despite the observed improvement in battery cycle performance through carbon coating in the two comparative examples, a significant gap still exists compared to the materials with uniformly distributed carbon in the embodiments of the present disclosure.
The above-mentioned specific embodiments further explain the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above embodiments are only specific ones of the present disclosure and are not used to limit the scope of protection of the present disclosure. Any modification, equivalent substitution, improvement, etc., made within the spirit and principles of the present disclosure should be included in the scope of protection of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111151405.1 | Sep 2021 | CN | national |
This application is a national phase entry under 35 U.S.C. § 371 of International Patent Application PCT/CN2022/080110, filed Mar. 10, 2022, designating the United States of America and published as International Patent Publication WO 2023/050726 A1 on Apr. 6, 2023, which claims the benefit under Article 8 of the Patent Cooperation Treaty to Chinese Patent Application Serial No. 202111151405.1, filed Sep. 29, 2021.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2022/080110 | 3/10/2022 | WO |
