Bromine modified high-rate graphite negative electrode material and preparation method thereof
The method of preparing bromine-modified high-rate graphite anode material by one-step carbonization solves the problem of poor rate performance of graphite anode material and realizes the simple and easy preparation of high-performance graphite anode material.
Patent Information
- Application Number
- CN202511534488.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-24
- Publication Date
- 2026-01-30
AI Technical Summary
Existing graphite anode materials have poor rate performance during rapid charge and discharge processes, and their preparation process is complicated, the reaction conditions are harsh, and the raw materials are expensive.
A one-step carbonization method was used to prepare bromine-modified high-rate graphite anode materials by mixing a specific bromine modifier with graphite and heat-treating it at 300–500 °C.
The prepared bromine-modified high-rate graphite anode material has a specific capacity of 109.5 mA h g-1 at a high current density of 1000 mA g-1, and still maintains a capacity of 271.1 mA h g-1 when it is reduced to 50 mA g-1. The process is simple, easy to operate, and the raw materials are inexpensive.
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Figure CN121439784A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of new energy storage technology, specifically to a bromine-modified high-rate graphite anode material and its preparation method. Background Technology
[0002] Graphite has advantages such as low cost, good conductivity, and stable properties, making it the most widely used negative electrode material in the battery field (such as lithium-ion and potassium-ion batteries). However, its poor rate performance makes it difficult to meet the requirements of rapid charging and discharging.
[0003] However, its poor rate capability makes it difficult to meet the needs of fast charging and discharging.
[0004] Creating hierarchical channels in graphite through chemical activation or template methods can shorten the ion diffusion path and thus improve rate performance. Pre-embedding some ions through chemical or electrochemical methods to expand the interlayer spacing and form a stable SEI is an effective means to improve the rate performance of graphite.
[0005] However, the above methods usually involve complex processes, harsh reaction conditions, or the use of expensive template agents. Summary of the Invention
[0006] This invention addresses the problems of cumbersome preparation processes, harsh reaction conditions, and expensive raw materials in existing preparation methods by using a simple one-step carbonization method to prepare a bromine-modified high-rate graphite anode material.
[0007] The technical solution of the present invention is as follows: Furthermore, the graphite includes any one or more combinations of flake graphite, expanded graphite, graphite oxide, and microcrystalline graphite, and the specific bromine modifier is one or more of the following in any proportion: hexabromobenzene, pentabromobenzene, pentabromotoluene, 1,6-dibromopyrene, 1,3,6,8-tetrabromopyrene, 1,3,6,8-tetrabromopyrene-4,5,9,10-tetraone, and decabromodiphenyl ethane. Furthermore, the mass ratio of the specific bromine modifier to graphite is 1 to 5, and the heat treatment temperature is 300 to 500°C.
[0008] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0009] The bromine-modified high-rate graphite anode material prepared by this invention has a simple and easy-to-operate process; the raw materials are simple and the reaction equipment is relatively simple, and it has great application prospects.
[0010] The bromine-modified high-rate graphite anode material obtained by the method of this invention exhibits a rate capability of 1000 mA g / g after potassium-ion half-cell rate testing. -1 At high current density, the specific capacitance is 109.5 mA hg. -1When it returns to 50mA g -1 At that time, the specific capacity can still recover to 271.1 mA hg. -1 The level. Attached Figure Description
[0011] Figure 1 This is a morphological structure diagram of Br-Gr-T1 in Embodiment 1 of the present invention.
[0012] Figure 2 This is a morphological structure diagram of Br-Gr-T2 in Embodiment 1 of the present invention.
[0013] Figure 3 This is a morphological structure diagram of Br-Gr-T3 in Embodiment 1 of the present invention.
[0014] Figure 4 This is the XRD pattern of Br-Gr-X in Embodiment 1 of the present invention.
[0015] Figure 5 This is the Raman diagram of Br-Gr-X in Embodiment 1 of the present invention.
[0016] Figure 6 The nitrogen adsorption-desorption curve of Br-Gr-T2 in Example 1 of this invention is shown.
[0017] Figure 7 This is the pore size distribution curve of Br-Gr-T2 in Example 1 of the present invention.
[0018] Figure 8 The images show the long-cycle performance curves of the potassium-ion battery anode materials Br-Gr-T2 and Gr prepared in Example 3 of this invention.
[0019] Figure 9 The rate performance curves of the potassium-ion battery anode materials Br-Gr-X and Gr prepared in Example 3 of this invention are shown.
[0020] Figure 10 The rate curves are for the potassium-ion battery anode materials Br-Gr-T2-Lr and Br-Gr-T2-Hr prepared in Example 3 of this invention. Detailed Implementation
[0021] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. Unless otherwise specified, the materials and reagents used in the embodiments of the present invention are commercially available.
[0022] Example 1: Synthesis of bromine-modified high-ratio graphite materials at different heat treatment temperatures
[0023] High-purity flake graphite was selected and subjected to multiple grinding, sieving, and washing processes to remove impurities. The treated graphite and hexabromobenzene were weighed on a balance at a mass ratio of 1:2. After grinding in a mortar, the mixture was placed in a corundum ceramic boat, which was then placed in the center of a tube furnace. Under a nitrogen atmosphere, the furnace was heated at three temperatures (T1, T2, and T3) for 60 minutes each. After cooling to room temperature, a black solid was obtained. This black solid was scraped off, pre-ground in a mortar, and weighed for later use, and labeled as Br-Gr-T1, Br-Gr-T2, and Br-Gr-T3, respectively.
[0024] Example 2: Synthesis of high-ratio bromine-modified graphite materials with different proportions
[0025] High-purity flake graphite was selected and subjected to multiple grinding, sieving, and washing processes to remove impurities. The treated graphite and hexabromobenzene were weighed on a balance at mass ratios of 1:1 and 1:2 (1:1 is labeled Lowratio, or Lr; 1:2 is labeled Highratio, or Hr). After grinding in a mortar, the mixture was placed in a corundum ceramic boat, which was then placed in the center of a tube furnace. The furnace was heated under a nitrogen atmosphere at a medium temperature (T2) for 60 minutes. After cooling to room temperature, a black solid was obtained. This black solid was scraped off, pre-ground in a mortar, and weighed for later use, labeled Br-Gr-T2-Lr and Br-Gr-T2-Hr, respectively.
[0026] Example 3: Electrochemical Performance Testing of Potassium-ion Battery Anode Materials
[0027] The negative electrode materials prepared in Examples 1 and 2, along with Gr, were mixed with super-pli and PVDF binder in a ratio of 7:2:1. An appropriate amount of NMP was added to prepare a slurry of suitable viscosity. The slurry was uniformly coated on copper foil, dried, and cut into negative electrode sheets using a tablet press. Potassium foil was used as the counter electrode, the electrolyte was 1M KPF6 / (EC+DEC)=1:1, and glass fiber was used as the separator. The resulting mixture was assembled into a potassium ion half cell.
[0028] The sample from Example 1 was scanned by electron microscopy, and the results are shown in the figure. Figure 1-3 As can be seen from the figure, the order of Br-Gr-X increases with increasing temperature, where... Figure 2 The Br-Gr-T2 particles are relatively uniformly distributed and have relatively smooth surfaces. Figure 3 Br-Gr-T3 exhibits significantly more severe particle aggregation. This aggregation reduces the effective contact between particles and between particles and the electrolyte, lowers the utilization rate of active sites within the particles, and ultimately affects the electrochemical performance of the active material.
[0029] The sample from Example 1 was subjected to X-ray diffraction, and the results are shown in the figure. Figure 4 The interlayer spacing of the three samples can be calculated from Bragg's formula to be 0.3359 nm, 0.3369 nm, and 0.3369 nm, respectively. The D values of the three samples can be calculated from Scherrer's formula to be 34.54, 23.0357, and 25.9145 nm, respectively. Based on the analysis of the interlayer spacing and crystallite size data, we can conclude that Br-Gr-T2 has a larger interlayer spacing and smaller crystallite size, so it should have a faster ion diffusion rate and a higher potassium storage capacity, exhibiting the best electrochemical performance.
[0030] The sample from Example 1 was subjected to Raman spectroscopy testing, and the results are shown in the figure. Figure 5 Defective carbon overtone peak (2D, 2957 cm⁻¹) -1 The intensity at the location indicates the presence of numerous graphene-like structures in the Br-Gr-X electrode. Among them, the Ig of the Br-Gr-T2 sample... D / I G The value of 0.65 indicates that the sample has fewer defects, a more complete graphene-like structure, better electrical conductivity, and more stable electrochemical performance. Since the planar structure of graphene-like materials effectively promotes electron transport, defects may hinder electron transport pathways, leading to increased resistance and decreased electrochemical performance. However, compared to Br-Gr-T2, the It of the Br-Gr-T3 sample is... D / I G The increase in α = 0.66 and the D peak indicates that Br-Gr-T3 contains more defects. These defects lead to changes in the electronic structure of Br-Gr-T3, thereby affecting its electron transport properties.
[0031] The specific surface area and porosity of the Br-Gr-T2 sample prepared in Example 1 were analyzed, and the results are shown in the figure. Figure 6-7 As can be seen from the figure, Br-Gr-T2 has a low specific surface area and abundant micro-mesoporous structure. The abundant pore structure can provide more storage sites for potassium ions and reduce side reactions between the electrolyte and the material.
[0032] Figure 8 The figure shows the long-cycle performance curves of the potassium-ion battery anode materials Br-Gr-X and Gr prepared in Example 3. As can be seen from the figure, the Br-Gr-T2 anode exhibits excellent cycle stability, maintaining 100.2 mA hg after 300 charge-discharge cycles at a current density of 1 A / g. -1 The capacity.
[0033] Figure 9The figure shows the rate performance curves of the potassium-ion battery anode materials Br-Gr-X and Gr prepared in Example 3. As can be seen from the figure, the Br-Gr-T2 electrode has better rate performance.
[0034] Figure 10 The rate performance of the potassium-ion battery anode materials Br-Gr-T2-Lr and Br-Gr-T2-Hr prepared in Example 3 can confirm the excellent rate performance of Br-Gr-T2-Hr.
Claims
1. A bromine-modified high-rate graphite negative electrode material, characterized by: The specific bromine modifier is a mixture of one or more of hexabromobenzene, pentabromobenzene, pentabromotoluene, 1,6-dibromopyrene, 1,3,6,8-tetrabromopyrene, 1,3,6,8-tetrabromopyrene-4,5,9,10-tetraone, decabromodiphenyl ethane, in any proportion.
2. A bromine-modified high-rate graphite negative electrode material, characterized by: The mass ratio of the specific bromine modifier to the graphite is 1-5, and the heat treatment temperature is 300-500 ℃.
3. The bromine-modified high-rate graphite negative material prepared by the method of claims 1-2, applied in a potassium ion battery, characterized in that, The specific bromine modifier and the graphite have high potassium storage specific capacity and significantly improved rate performance.