Patent Application
20230348274
The present disclosure relates to the field of battery materials, in particular to a silicon-doped graphene-based composite material and a preparation method and application thereof.
Lithium-ion batteries have the advantages of high energy density, long cycle life, and low environmental pollution. They have become the focus of research in countries around the world and have been widely used in computers, mobile phones and other portable electronic devices. However, with the rapid development of electric vehicles and advanced electronic equipment, higher requirements have been placed on the energy density of lithium-ion batteries. The key to improving the energy density of lithium-ion batteries lies in the improvement of electrode materials and the improvement of performance. At present, the negative electrode materials of commercial lithium-ion batteries are mainly graphite materials, due to their low theoretical specific capacity (only 372 m Ah/g) and poor rate performance. Therefore, scientists are committed to researching new high-capacity anode materials. Silicon has attracted much attention due to its high theoretical specific capacity (4200 mAh/g). Its lithium extraction voltage platform is low (<0.5 V), and it reacts with the electrolyte. It has low activity, abundant reserves in the earth's crust, and low price. As a negative electrode material for lithium-ion batteries, it has broad development prospects. However, the volume of silicon undergoes a huge change (>300%) during the process of deintercalating lithium, which causes the active material to rapidly pulverize and fall off during the charge-discharge cycle, resulting in the loss of electrical contact between the electrode active material and the current collector. At the same time, due to the huge volume expansion of the silicon material, the solid electrolyte interface membrane cannot exist stably in the electrolyte, resulting in reduced cycle life and capacity loss. In addition, the low electrical conductivity of silicon severely limits the full utilization of its capacity and the rate performance of silicon electrode materials. At present, the methods to solve these problems include: nanometerization, compositeization and other methods. Nanotechnology and silicon-carbon composite technology are the research focus of scientists, and significant progress has been made to improve the cycle performance and rate performance of silicon anode materials. At present, the recycling of waste lithium-ion batteries is mainly focused on recycling of materials for positive electrode. However, during the charging and discharging process of a battery, the structure of the negative electrode graphite has hardly changed, which is of great significance for recycling. Proton exchange membrane fuel cells are ideal power cells due to their advantages of low emission, high conversion efficiency and high energy density. Platinum-based catalysts are the best catalysts in oxygen reduction reaction of fuel cells. However, platinum is expensive and has few reserves. Therefore, it is necessary to develop low-platinum or non-platinum catalysts. Among them, carbon-based catalysts doped with non-noble metals have good catalytic activity and low preparation cost, so that they are one of the current research hotspots.
Silicon-based materials can be used as anode materials for lithium-ion batteries due to their high theoretical specific capacity. However, there are disadvantages such as huge volume effects during charging and discharging processes, low conductivity and unsatisfactory cycle life, which hinder their commercial application. But it cannot deny that the material has great application prospects. The research by scientists focuses on minimizing the first irreversible capacity, alleviating the volume expansion of the material, thereby improving the rate and cycle performance.
The present disclosure aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present disclosure provides a silicon-doped graphene composite material and a preparation method and application thereof. The silicon-doped graphene composite material has excellent charge and discharge capacity and structural stability. The material is based on the graphene structure, where silicon atoms replace the carbon atoms in the two-dimensional network structure of the graphene.
In order to achieve the above objectives, the present disclosure provides a silicon-doped graphene composite material, comprising silicon and graphene; wherein the silicon is doped in the graphene, which specifically means that in each layer of the graphene, part of the carbon atoms are replaced by silicon atoms, and the silicon atoms are connected to the other carbon atoms in each layer of the graphene by silicon-carbon bonds.
In some embodiments, the molar ratio of the silicon to the carbon in the silicon-doped graphene composite material is 1: (10-120).
In some other embodiments, the molar ratio of the silicon to the carbon in the silicon-doped graphene composite material is 1: (20-100).
A method for preparing a silicon-doped graphene composite material comprising the following steps:
In some embodiments, in step (1), the microwave heating is carried out at a temperature of 100° C.-120° C. for 20-40 min.
In some embodiments, in step (2), the organic acid is citric acid monohydrate.
In some embodiments, in step (2), the mass ratio of the nitrogen-doped graphene, the silicon nano particles and the organic acid is 1:(0.01-0.1):(1-3).
In some embodiments, in step (2), the solvent is anhydrous ethanol.
In some embodiments, in step (2), the solvothermal reaction is carried out at a temperature of 150° C.-160° C. for 6-10 h.
In some embodiments, in step (2), the washing is performed with a solvent of anhydrous ethanol, and the washings is carried out 3-5 times.
In some embodiments, the graphene is prepared by the following method:
In some other embodiments, in step 1), the heating temperature is 100° C.-150° C.
In some other embodiments, in step 1), the ultrasonic treatment is carried out for 30-60 min.
In some other embodiments, in step 2), the acid solution is at least one selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid.
In some other embodiments, in step 2), the concentration of the acid solution is 0.1-0.3 mol/L.
In some other embodiments, in step 2), the immersing is carried out for 12-24 h.
In some other embodiments, in step 2), the washing is carried out 3-5 times.
In some other embodiments, in step 2), the calcinating is carried out at a temperature of 700° C.-800° C. for 3-5 h in an atmosphere of an inert gas.
In some other embodiments, the inert gas is one selected form the group consisting of nitrogen, helium, neon, and argon.
In some other embodiments, in step 2), the calcinating is carried out with a heating rate of 2-6° C./min.
In some other embodiments, in step 3), the acid solution is prepared by mixing sulfuric acid and phosphoric acid in a volume ratio of 1:(1-3).
In some other embodiments, in step 3), the mass-volume ratio of the repaired graphite material, the potassium permanganate and the acid solution are 1:(0.3-0.5):(40-60).
In some other embodiments, in step 3), the heating reaction is carried out at a temperature of 80° C.-90° C. for 1-2 h.
In some other embodiments, in step 4), the volume ratio of the suspension to the hydrogen peroxide is 1:(1-3).
In some other embodiments, in step 4), the hydrothermal reaction is carried out at a temperature of 120° C.-130° C. for 6-8 h.
In some other embodiments, in step 4), the washing comprises the following steps: washing the filter residue with 0.1-0.2 mol/L hydrochloric acid 3-5 times, and then washing with ultrapure water 3-6 times.
In some other embodiments, in step 4), the drying is carried out at a temperature of 60° C.-80° C.
In some other embodiments, in step 4), the heating is carried out at a temperature of 100° C.-120° C. for 1-3 h in an inert gas atmosphere.
In some other embodiments, the inert gas is one selected from the group consisting of nitrogen, helium, neon, and argon.
A negative electrode material comprising the above-mentioned silicon-doped graphene composite material is provided.
A battery comprising the above-mentioned silicon-doped graphene composite material is provided.
In some other embodiments, the battery is a lithium ion battery.
The above and/or additional aspects and advantages of the present disclosure will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, in which:
In order to make technical solutions of the present disclosure more clearly understood by those skilled in the art, the following examples are listed for explanation. It should be pointed out that the following examples are not intended to limit the protection scope claimed by the present disclosure.
The method for preparing the silicon-doped graphene composite material of this embodiment comprises the following specific steps:
The method for preparing the silicon-doped graphene composite material of this embodiment comprises the following specific steps:
The method for preparing the silicon-doped graphene composite material of this embodiment comprises the following specific steps:
A method for preparing a nitrogen-containing graphene coated biomass carbon anode material comprising the following steps:
Dehydrating a plant raw material at low temperature and then carbonizing at high temperature to obtain a primary biomass carbon powder material; removing impurities to obtain a final biomass carbon powder material; mixing the biomass carbon powder material and a nitrogen-containing graphene precursor polymer solution in a certain mass ratio uniformly, and heating to obtain a curing micro cross-linked slurry, performing a spray-drying process to the slurry to remove solvent, and then subjecting a resulting power to particle shaping by means such as jet milling, followed by calcinating at high temperature to prepare a nitrogen-containing graphene-coated biomass carbon anode material.
In Comparative Example 2, a carbon material is coated on the surface of graphene and silicon materials. The preparation process is the same as that of Example 1 in the patent application text with the publication number CN 106876689 A. The specific process flow is as follows:
A lithium ion battery of this comparative example uses the above nitrogen-doped graphene-silicon composite anode material as a battery anode material, and the preparation method comprises the following steps:
Performance Testing:
The silicon-doped graphene composite material prepared in the foregoing Examples 1-3 and the nitrogen-containing graphene coated biomass carbon anode material prepared in Comparative Example 1 and the nitrogen-doped graphene-silicon composite anode material prepared in Comparative Example 2 were respectively used as an anode material while a lithium sheet was adopted as a cathode to assemble button cells. And their first discharge tests were carried out at a rate of 1 C. The results are shown in Table 1 and Table 2. It can be seen from Table 1 that at a rate of 1 C, the first discharge specific capacity of the silicon-doped graphene composite material prepared by the present disclosure is higher than that of the nitrogen-containing graphene-coated biomass carbon anode material of the comparative example. The first discharge specific capacity of the material obtained in Example 2 is 862.3 mAh/g, while the first discharge specific capacity of the one obtained in Comparative Example 1 is only 543.1 mAh/g, and the first discharge specific capacity of the material obtained in Comparative Example 2 is only 698.3 mAh/g. Therefore, the silicon-doped graphene composite material of the present disclosure has a property of high-capacity. According to Table 2, at 1 C rate, the cycle life of the silicon-doped graphene composite material prepared by the present disclosure is higher than that of the nitrogen-containing graphene-coated biomass carbon anode material of Comparative Example 1. After 500 cycles at 1 C rate, the capacity retention rate of the material in Example 2 is 95.9%, while the capacity retention rate of the one in Comparative Example 1 is only 72.8%.
The silicon-doped graphene composite material and the method and application thereof provided by the present disclosure have been described in detail above. Specific examples are used herein to illustrate the principles and implementation of the present disclosure. The above description of examples is only for the purpose of helping understand methods and core concepts of the present disclosure, including best modes, and also enables any person skilled in the art to practice the present disclosure, including manufacture and use of any device or system, and implementation of any combined methods. It should be noted that several improvements and modifications can be made by those skilled in the art to the present disclosure without departing from the principles of the present disclosure, which improvements and modifications also fall within the protection scope claimed by the claims. The protection scope of the present disclosure is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, these other embodiments should also be included within the scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202011637262.0 | Dec 2020 | CN | national |
The present application is a continuation application of PCT application No. PCT/CN2021/123391 filed on Oct. 13, 2021, which claims the benefit of Chinese Patent Application No. 202011637262.0 filed on Dec. 31, 2020. The contents of all of the aforementioned applications are incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2021/123391 | Oct 2021 | US |
| Child | 18217364 | US |
