Sodium-ion battery hard carbon negative electrode material rich in wide-layer graphite microcrystals and preparation method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN JANAENERGY TECH CO LTD
- Filing Date
- 2024-04-26
- Publication Date
- 2026-05-29
Smart Images
Figure CN118306988B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sodium-ion battery technology, specifically to a hard carbon anode material for sodium-ion batteries rich in wide-layered graphite microcrystals and its preparation method. Background Technology
[0002] With the rapid development of the new energy and energy storage industries, the demand for lithium-ion batteries is increasing daily, leading to soaring and volatile lithium resource prices in recent years. Therefore, finding alternative solutions is a current priority. Compared to lithium-ion batteries, sodium-ion batteries are favored due to their abundant raw material reserves, lower price, and higher safety.
[0003] Among various sodium-ion battery anode materials, hard carbon materials have advantages such as wide availability of raw materials, low price, high sodium storage capacity, and good cycle stability, making them the leading anode material for sodium-ion batteries. However, hard carbon materials still suffer from problems such as low specific capacity and poor rate performance, hindering the industrialization of sodium-ion batteries.
[0004] Hard carbon materials have a relatively complex structure, which can be considered to be composed of defects, graphite crystallites, and micropores. Among them, when the interlayer spacing of graphite crystallites is ≥0.37nm, they exhibit sodium storage activity; and the wider the interlayer spacing of graphite crystallites, the better the kinetics of sodium ion insertion and extraction between layers, and the better the rate performance.
[0005] To effectively improve the sodium storage capacity of hard carbon materials, a common approach is to increase the content of graphite microcrystals within the material, typically through metal ion-catalyzed graphitization. However, this method, while catalyzing the growth of graphite microcrystals, leads to excessively narrow interlayer spacing in the carbon layers, failing to effectively increase the sodium storage capacity and even causing a decrease in capacity. Furthermore, during the high-temperature carbonization process, metal nanoparticles form numerous pores within the hard carbon material, resulting in an excessively large specific surface area and extremely low initial charge-discharge efficiency. These factors hinder its industrial-scale application. Summary of the Invention
[0006] The purpose of this invention is to provide a method for preparing a hard carbon anode material for sodium-ion batteries rich in wide-layered graphite microcrystals, which has the characteristics of high sodium storage capacity, excellent electrochemical performance and good processing performance.
[0007] This invention can be achieved through the following technical solutions:
[0008] This invention discloses a method for preparing a hard carbon anode material for sodium-ion batteries rich in wide-layered graphite microcrystals, comprising the following steps:
[0009] S1. Pretreatment: The hard carbon raw material is crushed and screened to obtain powdered raw material;
[0010] S2. Preparation of hydrothermal mixture: The powdered raw materials, carbon nanomaterials, boron-containing compounds and topping agents obtained in step S1 are added to the reaction vessel, and deionized water is added and stirred evenly; the reaction vessel is controlled to undergo low-temperature graphitization treatment, and after the reaction is completed, it is naturally cooled to obtain hydrothermal mixture;
[0011] S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate;
[0012] S4. Crushing and Shaping: The low-temperature graphitization intermediate obtained in step S3 is crushed to obtain a low-temperature graphitization intermediate with controlled fineness.
[0013] S5. High-temperature graphitization: The low-temperature graphitization intermediate obtained in step S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for sodium-ion batteries.
[0014] In this invention, both boron-containing compounds and carbon nanomaterials can catalyze the graphitization of carbon layers. SP in carbon nanomaterials 2 Carbon undergoes a π-π conjugation effect with the aromatic rings in the carbon precursor, causing the carbon precursor to align and grow along the planar direction of graphene / carbon nanotubes / nanographite during hydrothermal processing, achieving directional growth of graphite crystallites and thus increasing the content of graphite crystallites. During hydrothermal processing, BOC bonds are formed, chemically bonding the carbon nanomaterials to the powdered carbon raw material, allowing the carbon nanomaterials to better catalyze graphitization. Simultaneously, boron atoms themselves have a strong promoting effect on the graphitization process of carbon materials. The combined application of carbon nanomaterials and boron-containing compounds results in a better catalytic effect. Furthermore, the layering agent contains other types of heteroatoms with atomic radii larger than carbon atoms, such as P and S. These heteroatoms participate in the reaction during low-temperature graphitization, doping into the carbon material. During subsequent high-temperature graphitization, they support the carbon interlayers, inhibiting the narrowing of the interlayer spacing and thus widening the carbon interlayer spacing.
[0015] Further, in step S2, the conditions for low-temperature graphitization are: heating to 200-400℃ at a heating rate of 1-10℃ / min, holding at this temperature for 3-10h, and stirring at a speed of 30-200 r / min.
[0016] Further, in step S2, the mass ratio of powdered raw material, carbon nanomaterial, boron-containing compound and topping agent is (91-99.3):(0.1-2):(0.1-2):(0.5-5).
[0017] Furthermore, in step S4, the pulverizing method is one or more of the following: roller mill, air jet mill, stirred mill, ball mill, and sand mill.
[0018] Further, in step S5, the inert gas is nitrogen and / or argon; the conditions for high-temperature graphitization are: heating rate of 0.5-5 ℃ / min, carbonization temperature of 1000-1600 ℃, and carbonization time of 2-10 h.
[0019] Furthermore, in step S1, the hard carbon raw material is one or more of the following: biomass raw material, phenolic resin, glucose, lignin, anthracite, lignite, cellulose, etc., and the biomass raw material is one or more of the following: walnut shell, nut shell, bamboo chips, sawdust, sugarcane residue, straw.
[0020] Furthermore, in step S2, the carbon nanomaterial is one or more of the following: single-walled carbon nanotubes, multi-walled carbon nanotubes, single-layer graphene, multi-layer graphene, nano-graphite microcrystals, carbon black, etc.
[0021] Furthermore, the boron-containing compound is one or more of boric acid, borax, boron halide, fluoroboric acid, and metal borides.
[0022] Furthermore, the topping agent is one or more of phosphoric acid, polyphosphoric acid, and sulfuric acid.
[0023] Another objective of this invention is to protect the hard carbon anode material for sodium-ion batteries, which is prepared using the above-described method.
[0024] This invention discloses a sodium-ion battery hard carbon anode material rich in wide-layered graphite microcrystals and its preparation method, which has the following beneficial effects:
[0025] First, it has a high sodium storage capacity. The synergistic effect of carbon nanomaterials and boron-containing compounds makes the interior of hard carbon materials rich in graphite microcrystals. The layering agent ensures a wide carbon layer spacing in hard carbon materials. The abundant wide-layer graphite microcrystals increase the active sites for sodium storage, thereby improving the sodium storage capacity of hard carbon materials.
[0026] Secondly, it exhibits excellent electrochemical performance. The wide carbon interlayer spacing facilitates the shuttle movement of sodium ions between carbon layers, enhancing the sodium ion insertion / extraction kinetics. Carbon nanomaterials possess excellent electronic conductivity; dispersed between hard carbon particles and tightly bound to them through chemical bonding, they form a stable and continuous electron transport network, further improving electron transport kinetics. This synergistic enhancement of ion and electron transport ensures the excellent rate performance of the hard carbon material in this invention.
[0027] Third, it has excellent processing performance. While increasing the content of graphite microcrystals inside the hard carbon material, the present invention widens the carbon layer spacing, which will not cause an increase in the specific surface area of the hard carbon material, thus avoiding the processing difficulty caused by the excessive specific surface area of the hard carbon anode material. Attached Figure Description
[0028] Figure 1 This is a SEM image of Example 1;
[0029] Figure 2 This is the SEM image of Comparative Example 1. Detailed Implementation
[0030] To enable those skilled in the art to better understand the technical solution of the present invention, the product of the present invention will be further described in detail below with reference to embodiments.
[0031] This invention discloses a method for preparing a hard carbon anode material for sodium-ion batteries rich in wide-layered graphite microcrystals, comprising the following steps:
[0032] S1. Pretreatment: The hard carbon raw material is crushed and screened to obtain powdered raw material;
[0033] S2. Preparation of hydrothermal mixture: The powdered raw materials, carbon nanomaterials, boron-containing compounds and topping agents obtained in step S1 are added to the reaction vessel, and deionized water is added and stirred evenly; the reaction vessel is controlled to undergo low-temperature graphitization treatment, and after the reaction is completed, it is naturally cooled to obtain hydrothermal mixture;
[0034] S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate;
[0035] S4. Crushing and Shaping: The low-temperature graphitization intermediate obtained in step S3 is crushed to obtain a low-temperature graphitization intermediate with controlled fineness.
[0036] S5. High-temperature graphitization: The low-temperature graphitization intermediate obtained in step S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for sodium-ion batteries.
[0037] Further, in step S2, the conditions for low-temperature graphitization are: heating to 200-400℃ at a heating rate of 1-10℃ / min, holding at this temperature for 3-10h, and stirring at a speed of 30-200 r / min.
[0038] Further, in step S2, the mass ratio of powdered raw material, carbon nanomaterial, boron-containing compound and topping agent is (91-99.3):(0.1-2):(0.1-2):(0.5-5).
[0039] Furthermore, in step S4, the pulverizing method is one or more of the following: roller mill, air jet mill, stirred mill, ball mill, and sand mill.
[0040] Further, in step S5, the inert gas is nitrogen and / or argon; the conditions for high-temperature graphitization are: heating rate of 0.5-5 ℃ / min, carbonization temperature of 1000-1600 ℃, and carbonization time of 2-10 h.
[0041] Furthermore, in step S1, the hard carbon raw material is one or more of the following: biomass raw material, phenolic resin, glucose, lignin, anthracite, lignite, cellulose, etc., and the biomass raw material is one or more of the following: walnut shell, nut shell, bamboo chips, sawdust, sugarcane residue, straw.
[0042] Furthermore, in step S2, the carbon nanomaterial is one or more of the following: single-walled carbon nanotubes, multi-walled carbon nanotubes, single-layer graphene, multi-layer graphene, and nano-graphite microcrystals.
[0043] Furthermore, the boron-containing compound is one or more of boric acid, borax, boron halide, fluoroboric acid, and metal borides.
[0044] Furthermore, the topping agent is one or more of phosphoric acid, polyphosphoric acid, and sulfuric acid.
[0045] Another objective of this invention is to protect the hard carbon anode material for sodium-ion batteries, which is prepared using the above-described method.
[0046] Example 1
[0047] This embodiment relates to a hard carbon anode material for sodium-ion batteries rich in wide-layered graphite microcrystals, the preparation method of which includes the following steps:
[0048] S1. Pretreatment: The bamboo raw material is crushed and screened to obtain bamboo powder with a particle size of less than 2mm.
[0049] S2. Preparation of the hydrothermal mixture: The bamboo powder, graphene, boric acid, and phosphoric acid obtained in step S1 were added to a reaction vessel, and deionized water was added and stirred until homogeneous. The reaction vessel was heated to 250°C at a rate of 5°C, and held at this temperature for 5 hours while stirring at a speed of 50 r / min. After the reaction was completed, the mixture was allowed to cool naturally to obtain the hydrothermal mixture. The mass ratio of bamboo powder, graphene, boric acid, and phosphoric acid was 95:1:1:3.
[0050] S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate.
[0051] S4. Crushing and Shaping: Using a mechanical mill, the low-temperature graphitization intermediate obtained in step S3 is crushed to obtain a low-temperature graphitization intermediate with a certain fineness.
[0052] S5. High-temperature graphitization: A low-temperature graphitization intermediate of a certain fineness is placed in a high-temperature furnace and heated to 1200 ℃ at a heating rate of 1 ℃ / min under a nitrogen atmosphere, and held for 1 h to obtain the hard carbon material of Example 1.
[0053] The electrochemical performance of the obtained materials was tested as follows: Hard carbon material, Super P, CMC, and SBR were mixed in a mass ratio of 94:1.5:2:2.5 to form a slurry. A 120 μm four-sided coating tool was used to coat the black slurry onto copper foil, and the membrane was then dried in a vacuum oven at 100°C for 2 hours. The electrode membrane was punched into a 0.6 mm radius disc using a die-cutting machine. Using metallic sodium as the counter electrode, 1 mol / L NaClO4EC+DEC (1:1 vol%) as the electrolyte, and a PP / PE / PP three-layer separator, a CR2016 button cell was assembled in a glove box. The above button cell was subjected to constant current charge-discharge testing at a current density of 0.1C (1C = 300 mAh / g) and a voltage range of 2–0.005 V.
[0054] Comparative Example 1
[0055] This embodiment relates to a hard carbon anode material for sodium-ion batteries, the preparation method of which includes the following steps:
[0056] S1. Pretreatment: The bamboo raw material is crushed and screened to obtain bamboo powder with a particle size of less than 2mm.
[0057] S2. Preparation of the hydrothermal mixture: The bamboo powder and phosphoric acid obtained in step S1 were added to a reaction vessel, and deionized water was added and stirred until homogeneous. The temperature of the reaction vessel was increased to 250°C at a rate of 5°C, and maintained at this temperature for 5 hours while stirring at a speed of 50 r / min. After the reaction was completed, the mixture was allowed to cool naturally to obtain the hydrothermal mixture. The mass ratio of bamboo powder, graphene, boric acid, and phosphoric acid was 95:3.
[0058] S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate.
[0059] S4. Grinding and refining: Using a mechanical mill, the low-temperature graphitization intermediate obtained in step S3 is ground to obtain a low-temperature graphitization intermediate of a certain fineness.
[0060] S5. High-temperature graphitization: A low-temperature graphitization intermediate of a certain fineness is placed in a high-temperature furnace and heated to 1200 ℃ at a heating rate of 1 ℃ / min under a nitrogen atmosphere, and held for 1 h to obtain the hard carbon material of Comparative Example 1.
[0061] Comparative Example 2
[0062] This embodiment relates to a hard carbon anode material for sodium-ion batteries, the preparation method of which includes the following steps:
[0063] S1. Pretreatment: The bamboo raw material is crushed and screened to obtain bamboo powder with a particle size of less than 2mm.
[0064] S2. Preparation of the hydrothermal mixture: The bamboo powder, graphene, and boric acid obtained in step S1 were added to a reaction vessel, and deionized water was added and stirred until homogeneous. The reaction vessel was heated to 250°C at a rate of 5°C, and held at this temperature for 5 hours while stirring at a speed of 50 r / min. After the reaction was completed, the mixture was allowed to cool naturally to obtain the hydrothermal mixture. The mass ratio of bamboo powder, graphene, boric acid, and phosphoric acid was 95:1:1.
[0065] S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate.
[0066] S4. Crushing and Shaping: Using a mechanical mill, the low-temperature graphitization intermediate obtained in step S3 is crushed to obtain a low-temperature graphitization intermediate with a certain fineness.
[0067] S5. High-temperature graphitization: A low-temperature graphitization intermediate of a certain fineness is placed in a high-temperature furnace and heated to 1200 ℃ at a heating rate of 1 ℃ / min under a nitrogen atmosphere, and held for 1 h to obtain the hard carbon material of Comparative Example 2.
[0068] Comparative Example 3
[0069] This embodiment relates to a hard carbon anode material for sodium-ion batteries, the preparation method of which includes the following steps:
[0070] S1. Pretreatment: The bamboo raw material is crushed and screened to obtain bamboo powder with a particle size of less than 2mm.
[0071] S2. Preparation of hydrothermal mixture: Add the bamboo powder obtained in step S1 to the reaction vessel, add deionized water and stir evenly; control the reaction vessel to heat up to 250°C at a heating rate of 5°C, keep at this temperature for 5 hours, and stir at a speed of 50 r / min. After the reaction is completed, cool naturally to obtain hydrothermal mixture.
[0072] S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate.
[0073] S4. Crushing and Shaping: Using a mechanical mill, the low-temperature graphitization intermediate obtained in step S3 is crushed to obtain a low-temperature graphitization intermediate with a certain fineness.
[0074] S5. High-temperature graphitization: A low-temperature graphitization intermediate of a certain fineness is placed in a high-temperature furnace and heated to 1200 ℃ at a heating rate of 1 ℃ / min under a nitrogen atmosphere, and held for 1 h to obtain the hard carbon material of Comparative Example 2.
[0075] The electrochemical performance of the obtained materials was tested as follows: Hard carbon material, Super P, CMC, and SBR were mixed in a mass ratio of 94:1.5:2:2.5 to form a slurry. A 120 μm four-sided coating tool was used to coat the black slurry onto copper foil, and the membrane was then dried in a vacuum oven at 100°C for 2 hours. The electrode membrane was punched into a 0.6 mm radius disc using a die-cutting machine. Using metallic sodium as the counter electrode, 1 mol / L NaClO4EC+DEC (1:1 vol%) as the electrolyte, and a PP / PE / PP three-layer separator, a CR2016 button cell was assembled in a glove box. The above button cell was subjected to constant current charge-discharge testing at a current density of 0.1C (1C = 300 mAh / g) and a voltage range of 2–0.005 V.
[0076] The carbon interlayer spacing of the samples was tested using X-ray diffraction (XRD). Based on the test results, the average carbon interlayer spacings of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were calculated to be 0.39 nm, 0.40 nm, 0.36 nm, and 0.37 nm, respectively. A comparison of Example 1 and Comparative Example 2 shows that boric acid and graphene-catalyzed graphitization narrows the carbon interlayer spacing. A comparison of Example 1, Comparative Example 1, and Comparative Example 3 shows that the introduction of phosphoric acid significantly increases the carbon interlayer spacing.
[0077] The average thickness (Lc) of the graphite crystallites in the samples was calculated based on the XRD test results. The average values of Lc for Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were 1.20 nm, 0.94 nm, 1.23 nm, and 0.97 nm, respectively. The comparison results of Example 1, Comparative Example 2, and Comparative Example 1 show that phosphoric acid and boric acid can increase the thickness of graphite crystallites and promote their growth.
[0078] Figure 1 and Figure 2 The images are scanning electron microscope (SEM) images of Example 1 and Comparative Example 1, respectively. A large number of graphite microcrystals were observed in Example 1, while the number of graphite microcrystals observed in Comparative Example 1 was relatively small.
[0079] Electrochemical performance tests showed that Example 1 had a specific capacity of 336 mAh / g, an initial efficiency of 93%, and a capacity retention of 85% at 5C; Comparative Example 3 had a specific capacity of 295 mAh / g, an initial efficiency of 92%, and a capacity retention of 70% at 5C. The rate performance of Example 1 was significantly improved. The improved specific capacity of Example 1 is attributed to the abundance of wide-layered graphite microcrystals within the hard carbon material, which increases the active sites for sodium storage, thereby enhancing the sodium storage capacity. The improved rate performance of Example 1 is due to two factors: firstly, the wide carbon interlayer spacing facilitates the shuttle movement of sodium ions between carbon layers, improving sodium ion insertion / extraction kinetics; secondly, graphene itself has excellent electronic conductivity, and the doped graphene is chemically bonded to the hard carbon material, forming a stable and continuous electron transport network, thus improving electron transport kinetics. The synergistic improvement in ion transport and electron transport ensures the excellent rate performance of the hard carbon material in Example 1.
[0080] Example 2
[0081] This embodiment relates to a hard carbon anode material for sodium-ion batteries rich in wide-layered graphite microcrystals, and its preparation method includes the following steps:
[0082] S1. Pretreatment: The hard carbon raw material is crushed and screened to obtain powdered raw material;
[0083] S2. Preparation of hydrothermal mixture: The powdered raw materials, carbon nanomaterials, boron-containing compounds and topping agents obtained in step S1 are added to the reaction vessel, and deionized water is added and stirred evenly; the reaction vessel is controlled to undergo low-temperature graphitization treatment, and after the reaction is completed, it is naturally cooled to obtain hydrothermal mixture;
[0084] S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate;
[0085] S4. Crushing and Shaping: The low-temperature graphitization intermediate obtained in step S3 is crushed to obtain a low-temperature graphitization intermediate with controlled fineness.
[0086] S5. High-temperature graphitization: The low-temperature graphitization intermediate obtained in step S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for sodium-ion batteries.
[0087] In step S2 of this embodiment, the conditions for low-temperature graphitization are as follows: heating to 300°C at a heating rate of 10°C / min, holding at this temperature for 3-h, and stirring at a speed of 200 r / min. The mass ratio of powdered raw materials, carbon nanomaterials, boron-containing compounds, and topping agents is 95.3:0.1:2:3.
[0088] In step S4 of this embodiment, the pulverizing method is a roller mill or air jet mill.
[0089] In step S5 of this embodiment, the inert gas is nitrogen; the conditions for high-temperature graphitization are: heating rate of 5 ℃ / min, carbonization temperature of 1300 ℃, and carbonization time of 2h.
[0090] In step S1 of this embodiment, the hard carbon raw materials are biomass raw materials and phenolic resin, and the biomass raw materials are walnut shells, nut shells, and bamboo strips.
[0091] In step S2 of this embodiment, the carbon nanomaterial is a single-walled carbon nanotube or a multi-walled carbon nanotube. The boron-containing compound is boric acid. The layering agent is polyphosphoric acid.
[0092] Example 3
[0093] This embodiment relates to a hard carbon anode material for sodium-ion batteries rich in wide-layered graphite microcrystals, and its preparation method includes the following steps:
[0094] S1. Pretreatment: The hard carbon raw material is crushed and screened to obtain powdered raw material;
[0095] S2. Preparation of hydrothermal mixture: The powdered raw materials, carbon nanomaterials, boron-containing compounds and topping agents obtained in step S1 are added to the reaction vessel, and deionized water is added and stirred evenly; the reaction vessel is controlled to undergo low-temperature graphitization treatment, and after the reaction is completed, it is naturally cooled to obtain hydrothermal mixture;
[0096] S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate;
[0097] S4. Crushing and Shaping: The low-temperature graphitization intermediate obtained in step S3 is crushed to obtain a low-temperature graphitization intermediate with controlled fineness.
[0098] S5. High-temperature graphitization: The low-temperature graphitization intermediate obtained in step S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for sodium-ion batteries.
[0099] In step S2 of this embodiment, the conditions for low-temperature graphitization are as follows: heating to 200°C at a heating rate of 5°C / min, holding at this temperature for 10 hours, and stirring at a speed of 100 r / min. The mass ratio of powdered raw materials, carbon nanomaterials, boron-containing compounds, and topping agents is 91:2:1:0.5.
[0100] In step S4 of this embodiment, the pulverizing method is: stirring mill, ball mill.
[0101] In step S5 of this embodiment, the inert gas is argon; the conditions for high-temperature graphitization are: heating rate of 3 ℃ / min, carbonization temperature of 1000 ℃, and carbonization time of 10 h.
[0102] In step S1 of this embodiment, the hard carbon raw materials are glucose and lignin.
[0103] In step S2 of this embodiment, the carbon nanomaterial is single-layer graphene or multi-layer graphene. The boron-containing compound is borax or boron halide. The layering agent is phosphoric acid or polyphosphoric acid.
[0104] Example 4
[0105] This embodiment relates to a hard carbon anode material for sodium-ion batteries rich in wide-layered graphite microcrystals, and its preparation method includes the following steps:
[0106] S1. Pretreatment: The hard carbon raw material is crushed and screened to obtain powdered raw material;
[0107] S2. Preparation of hydrothermal mixture: The powdered raw materials, carbon nanomaterials, boron-containing compounds and topping agents obtained in step S1 are added to the reaction vessel, and deionized water is added and stirred evenly; the reaction vessel is controlled to undergo low-temperature graphitization treatment, and after the reaction is completed, it is naturally cooled to obtain hydrothermal mixture;
[0108] S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate;
[0109] S4. Crushing and Shaping: The low-temperature graphitization intermediate obtained in step S3 is crushed to obtain a low-temperature graphitization intermediate with controlled fineness.
[0110] S5. High-temperature graphitization: The low-temperature graphitization intermediate obtained in step S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for sodium-ion batteries.
[0111] In step S2 of this embodiment, the conditions for low-temperature graphitization are as follows: heating to 400°C at a heating rate of 1°C / min, holding at this temperature for 6 hours, and stirring at a speed of 30 r / min. The mass ratio of powdered raw materials, carbon nanomaterials, boron-containing compounds, and topping agents is 99.3:1:0.1:5.
[0112] In step S4 of this embodiment, the pulverization method is ball milling or sand milling.
[0113] In step S5 of this embodiment, the inert gases are nitrogen and argon; the conditions for high-temperature graphitization are: heating rate of 0.5 ℃ / min, carbonization temperature of 1600 ℃, and carbonization time of 6 h.
[0114] In step S1 of this embodiment, the hard carbon raw materials are biomass raw materials, lignite, and cellulose. The biomass raw materials are bamboo chips, wood chips, sugarcane residue, and straw.
[0115] In step S2 of this embodiment, the carbon nanomaterials are single-walled carbon nanotubes or nano-graphite crystals. The boron-containing compounds are boron halides, fluoroboric acid, or metal borides. The layering agents are phosphoric acid or sulfuric acid.
[0116] Example 5
[0117] This embodiment relates to a hard carbon anode material for sodium-ion batteries rich in wide-layered graphite microcrystals, and its preparation method includes the following steps:
[0118] S1. Pretreatment: The hard carbon raw material is crushed and screened to obtain powdered raw material;
[0119] S2. Preparation of hydrothermal mixture: The powdered raw materials, carbon nanomaterials, boron-containing compounds and topping agents obtained in step S1 are added to the reaction vessel, and deionized water is added and stirred evenly; the reaction vessel is controlled to undergo low-temperature graphitization treatment, and after the reaction is completed, it is naturally cooled to obtain hydrothermal mixture;
[0120] S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate;
[0121] S4. Crushing and Shaping: The low-temperature graphitization intermediate obtained in step S3 is crushed to obtain a low-temperature graphitization intermediate with controlled fineness.
[0122] S5. High-temperature graphitization: The low-temperature graphitization intermediate obtained in step S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for sodium-ion batteries.
[0123] In step S2 of this embodiment, the conditions for low-temperature graphitization are as follows: heating to 300°C at a heating rate of 5°C / min, holding at this temperature for 6 hours, and stirring at a speed of 120 r / min. The mass ratio of powdered raw materials, carbon nanomaterials, boron-containing compounds, and topping agents is 97.3:0.8:0.8:3.
[0124] In step S4 of this embodiment, the pulverizing method is sand milling.
[0125] In step S5 of this embodiment, the inert gases are nitrogen and argon; the conditions for high-temperature graphitization are: heating rate of 3℃ / min, carbonization temperature of 1400℃, and carbonization time of 6 h.
[0126] In step S1 of this embodiment, the hard carbon raw material is a biomass raw material, which includes walnut shells, nut shells, bamboo chips, sawdust, sugarcane residue, and straw.
[0127] In step S2 of this embodiment, the carbon nanomaterial is a single-walled carbon nanotube, a layered graphene, a multilayered graphene, or a nanocrystalline graphite. The boron-containing compound is boric acid, borax, boron halide, or fluoroboric acid. The layering agent is phosphoric acid or polyphosphoric acid.
[0128] The above embodiments are merely specific examples of the present invention, and their descriptions are quite specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these obvious substitutions all fall within the protection scope of the present invention.
Claims
1. A method for preparing a hard carbon anode material for sodium-ion batteries rich in broad-layered graphite microcrystals, characterized in that... Includes the following steps: S1. Pretreatment: The hard carbon raw material is crushed and screened to obtain powdered raw material; S2. Preparation of hydrothermal mixture: The powdered raw materials, carbon nanomaterials, boron-containing compounds and topping agents obtained in step S1 are added to the reaction vessel, and deionized water is added and stirred evenly; the reaction vessel is controlled to carry out low-temperature graphitization treatment, the low-temperature graphitization temperature is 200-400℃, and the reaction is naturally cooled after completion to obtain hydrothermal mixture; S3. Separation of low-temperature graphitization intermediate: The hydrothermal mixture obtained in step S2 is centrifuged and dried to obtain the low-temperature graphitization intermediate; S4. Crushing and Shaping: The low-temperature graphitization intermediate obtained in step S3 is crushed to obtain a low-temperature graphitization intermediate with controlled fineness. S5. High-temperature graphitization: The low-temperature graphitization intermediate obtained in step S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere. The carbonization temperature is 1000-1600 ℃ to obtain a hard carbon anode material for sodium-ion batteries.
2. The method for preparing the sodium-ion battery hard carbon anode material rich in wide-layered graphite microcrystals according to claim 1, characterized in that: In step S2, the conditions for low-temperature graphitization are as follows: the temperature is increased to the low-temperature graphitization temperature at a heating rate of 1-10℃ / min, and the temperature is maintained at this temperature for 3-10 hours, while stirring at a speed of 30-200 r / min.
3. The method for preparing the sodium-ion battery hard carbon anode material rich in wide-layered graphite microcrystals according to claim 1, characterized in that: In step S2, the mass ratio of powdered raw material, carbon nanomaterial, boron-containing compound and topping agent is (91-99.3):(0.1-2):(0.1-2):(0.5-5).
4. The method for preparing the sodium-ion battery hard carbon anode material rich in wide-layered graphite microcrystals according to claim 1, characterized in that: In step S4, the pulverizing method is one or more of the following: roller mill, air jet mill, stirred mill, ball mill, and sand mill.
5. The method for preparing the sodium-ion battery hard carbon anode material rich in wide-layered graphite microcrystals according to claim 1, characterized in that: In step S5, the inert gas is nitrogen and / or argon; the conditions for high-temperature graphitization are: heating rate of 0.5-5 °C / min and carbonization time of 2-10 h.
6. The method for preparing the sodium-ion battery hard carbon anode material rich in wide-layered graphite microcrystals according to claim 5, characterized in that: In step S1, the hard carbon raw material is one or more of the following: biomass raw material, phenolic resin, glucose, lignin, anthracite, lignite, and cellulose. The biomass raw material is one or more of the following: walnut shell, nut shell, bamboo chips, sawdust, sugarcane residue, and straw.
7. The method for preparing the sodium-ion battery hard carbon anode material rich in wide-layered graphite microcrystals according to claim 1, characterized in that: In step S2, the carbon nanomaterial is one or more of the following: single-walled carbon nanotubes, multi-walled carbon nanotubes, single-layer graphene, multi-layer graphene, nano-graphite microcrystals, and carbon black.
8. The method for preparing the sodium-ion battery hard carbon anode material rich in wide-layered graphite microcrystals according to claim 1, characterized in that: The boron-containing compound is one or more of boric acid, borax, boron halide, fluoroboric acid, and metal borides.
9. The method for preparing the sodium-ion battery hard carbon anode material rich in wide-layered graphite microcrystals according to claim 1, characterized in that: The topping agent is one or more of phosphoric acid, polyphosphoric acid, and sulfuric acid.
10. A hard carbon anode material for sodium-ion batteries, characterized in that... It is prepared by the preparation method described in any one of claims 1-9.