Carbon material for sodium ion battery negative electrode, preparation method and application

Abstract

The application discloses a carbon material for a sodium ion battery negative electrode, a preparation method and application, and the Raman spectrum of the carbon material satisfies characteristics 1 and 2: characteristic 1 0.4 <= I G / I D <= 0.5; and characteristic 2 0.35 <= I D3+D4 / I All <= 0.42; and / or, I D3 / I Gˋ+D2+D3 >= 0.14; wherein I G is the area of a G peak in the Raman spectrum; I D is the area of a D peak in the Raman spectrum; I D3+D4 is the total area of D3 and D4 peaks in the fitted Raman spectrum; I All is the total area of G', D1, D2, D3 and D4 peaks in the fitted Raman spectrum; I D3 is the area of the D3 peak in the fitted Raman spectrum; and I Gˋ+D2+D3 is the total area of G', D2 and D3 peaks in the fitted Raman spectrum. The structure of the carbon material for the sodium ion battery negative electrode satisfies the above requirements, and is beneficial to the improvement of reversible capacity, first circle discharge specific capacity and rate performance.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery anode material technology, and more specifically, to carbon materials for sodium-ion battery anodes, their preparation methods, and their applications. Background Technology

[0002] In recent years, sodium-ion batteries have shown promise for large-scale energy storage due to the abundance and low cost of sodium resources. The successful commercialization of sodium-ion batteries largely depends on innovation in low-cost, high-performance electrode active materials. However, while graphite is widely used as the anode in lithium-ion batteries, the smaller interlayer spacing of graphite anode materials severely hinders the insertion and extraction of sodium ions because the radius of Na ions (0.103 nm) is larger than that of Li ions (0.071 nm). This makes existing commonly used anode materials in lithium-ion batteries (such as graphite) unsuitable for direct use in sodium-ion batteries. In 2000, Stevens and Dahn et al. discovered that hard carbon has a 300 mAh g⁻¹ capacity. -1 The reversible sodium capacity has led researchers to focus on the study of amorphous carbon anodes, especially hard carbon anode materials.

[0003] Common precursors for preparing hard carbon include biomass, polymers, and coal. Among these, coal, as a fossil energy source with abundant reserves and wide distribution in my country, has a higher carbon content and density compared to small-molecule substances and biomass, making it the highest-quality carbon source in nature besides graphite and diamond. However, coal is classified into different ranks based on its degree of metamorphism, and different ranks exhibit different structural characteristics. This leads to significant differences in the performance of anode materials used in sodium-ion batteries. Therefore, it is particularly necessary to provide a high-capacity carbon material that can be prepared using coal as a precursor. Summary of the Invention

[0004] The purpose of this invention is to provide carbon materials, preparation methods and applications for sodium-ion battery anodes, and to provide a high-capacity carbon material that can use coal as a precursor.

[0005] This invention is implemented as follows:

[0006] In a first aspect, the present invention provides a carbon material for a sodium-ion battery anode, wherein the Raman spectrum of the carbon material satisfies features ① and feature ②:

[0007] Feature ① 0.4≤I G / I D ≤0.5;

[0008] Feature ② 0.35≤I D3+D4 / I All ≤0.42; and / or, I D3 / I Gˋ+D2+D3≥0.14;

[0009] Among them, I G I represents the area of ​​the G peak in the Raman spectrum. D I represents the area of ​​peak D in the Raman spectrum. D3+D4 To fit the total area of ​​peaks D3 and D4 in the Raman spectrum; I All To fit the total area of ​​the Gˋ, D1, D2, D3, and D4 peaks in the Raman spectrum; I D3 To fit the area of ​​the D3 peak in the Raman spectrum; I Gˋ+D2+D3 To fit the total area of ​​the Gˋ, D2, and D3 peaks in the Raman spectrum;

[0010] The fitted Raman spectrum was obtained by deconvolution of the Raman spectrum; the peak value of the Gˋ peak is at 1560 cm⁻¹. -1 ~1600cm -1 Between; the peak value of D1 is at 1330 cm⁻¹ -1 ~1370cm -1 Between; the peak value of D2 is at 1480 cm⁻¹ -1 ~1520cm -1 The peak value of D3 is between 1610 cm⁻¹. -1 ~1640cm -1 Between; the peak value of D4 is at 1180 cm⁻¹ -1 ~1220cm -1 between.

[0011] In an optional embodiment, the carbon material satisfies at least one of the following characteristics:

[0012] ad 002 The wavelength is 0.36nm-0.39nm;

[0013] b.Lc is 1.20nm-1.4nm;

[0014] c.Lc / d 002 The value is 3.35-3.65;

[0015] d. Closed-cell ratio 40%-65%;

[0016] e. The carbon material includes amorphous carbon;

[0017] f. Reversible specific capacity > 300mAh / g;

[0018] h. First-cycle discharge specific capacity > 320mAh / g;

[0019] i. First-time efficacy > 90%.

[0020] Secondly, the present invention provides a method for preparing the carbon material for the negative electrode of a sodium-ion battery as described in the foregoing embodiments, comprising:

[0021] The slurry containing raw coal powder is subjected to flotation to obtain floating matter and settling matter;

[0022] The floating material is acid-washed to obtain deashed floating material;

[0023] The deashed floating material is subjected to pre-oxidation, steam activation and calcination in sequence to obtain the carbon material.

[0024] In an optional embodiment, the particle size of the raw coal powder is less than 200 mesh;

[0025] And / or, in the flotation step, the ratio of raw coal powder to water in the slurry is 1g:(15-25)cm³. 3 ;

[0026] And / or, the slurry further includes a collector and / or a foaming agent;

[0027] And / or, in the flotation step, the enrichment rate of the floating material is 60%-80%, and the enrichment rate of the sinking material is 10%-40%.

[0028] In an optional embodiment, the collector is selected from at least one of oleic acid, hexadecyltrimethylammonium bromide, and sodium dodecyl sulfate;

[0029] And / or, the content of the collector in the slurry is 0.25 g / L-0.3 g / L;

[0030] And / or, the foaming agent includes one or more of n-octanol, sec-octanol, cyclohexanol, pine oil, industrial fusel oil, or methyl isobutyl methanol;

[0031] And / or, the foaming agent content in the slurry is 0.08 g / L-0.1 g / L.

[0032] In an optional embodiment, the pickling includes sequentially performing hydrochloric acid washing and hydrofluoric acid washing on the floating material;

[0033] And / or, after the hydrochloric acid wash and hydrofluoric acid wash, the floating matter is washed with deionized water until neutral.

[0034] In an optional embodiment, the concentration of the hydrochloric acid solution used for hydrochloric acid washing is 3mol / L-7mol / L, and the amount of hydrochloric acid solution used per gram of floating matter in the hydrochloric acid washing step is less than 10mL.

[0035] And / or, the concentration of the hydrofluoric acid solution used in the hydrofluoric acid washing is 35wt%-45wt%, and the amount of hydrofluoric acid solution used per gram of floating matter in the hydrofluoric acid washing step is less than 10mL.

[0036] In an optional embodiment, the pre-oxidation temperature is 250℃-300℃, the time is 3h-6h, and the atmosphere is an oxidizing atmosphere;

[0037] And / or, the activation temperature is 900℃-950℃, and the time is 2h-5h;

[0038] And / or, the activation method is physical activation, the activation gas is water vapor and / or carbon dioxide, and the activation gas flow rate is 0.1 L / min-2 L / min;

[0039] And / or, the activation method is chemical activation, and the activator is selected from at least one of KOH, NaOH, phosphoric acid, and potassium bicarbonate, and the amount added is 5wt%-40wt% of the pre-oxidized and deashed floating matter;

[0040] And / or, the calcination temperature is 1200℃-1300℃, and the time is 2h-4h.

[0041] Thirdly, the present invention provides a negative electrode sheet comprising the carbon material described in the foregoing embodiments.

[0042] Fourthly, the present invention provides a sodium-ion battery, including the negative electrode sheet described in the foregoing embodiments.

[0043] The present invention has the following beneficial effects:

[0044] The carbon material structure used in the negative electrode of sodium-ion batteries meets the above requirements, which is beneficial to improving reversible capacity, first-cycle discharge specific capacity and rate performance.

[0045] The carbon material for the sodium-ion battery anode in this application can be prepared using coal as a precursor, which is beneficial for reducing costs and enabling large-scale industrial production.

[0046] The preparation process described in this application is simple, with relatively mild process conditions that avoid excessive corrosive activation (such as alkaline solutions), making it environmentally friendly. It also provides a new direction for achieving high-value-added utilization of low-rank coal. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 Microscopic morphology images of raw coal SY, vitrinite enrichment component SY-RV1, and inert component SY-RI1 in Example 1;

[0049] Figure 2 XRD diffraction pattern and fitted peak diagram of SY-RVC-H1;

[0050] Figure 3 Raman spectra of SY-RVC-H1 and SY-RIC-H1;

[0051] Figure 4 The Raman fitting peak of SY-RVC-H1;

[0052] Figure 5 The diagram shows the electrochemical performance of some hard carbon materials.

[0053] Figure 6 This refers to the rate cycling performance of some hard carbon materials. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0055] This invention provides a carbon material for the negative electrode of a sodium-ion battery, wherein the Raman spectrum of the carbon material satisfies characteristics ① and ②:

[0056] Feature ① 0.4≤I G / I D ≤0.5;

[0057] Feature ② 0.35≤I D3+D4 / I All ≤0.42; and / or, I D3 / I Gˋ+D2+D3 ≥0.14;

[0058] Among them, I G I represents the area of ​​the G peak in the Raman spectrum. D I represents the area of ​​peak D in the Raman spectrum. D3+D4 To fit the total area of ​​peaks D3 and D4 in the Raman spectrum; I All To fit the total area of ​​the Gˋ, D1, D2, D3, and D4 peaks in the Raman spectrum; I D3 To fit the area of ​​the D3 peak in the Raman spectrum; I Gˋ+D2+D3 To fit the total area of ​​the Gˋ, D2, and D3 peaks in the Raman spectrum;

[0059] The fitted Raman spectrum was obtained by deconvolution of the Raman spectrum; the peak value of the Gˋ peak is at 1560 cm⁻¹. -1 ~1600cm -1Between; the peak value of D1 is at 1330 cm⁻¹ -1 ~1370cm -1 Between; the peak value of D2 is at 1480 cm⁻¹ -1 ~1520cm -1 The peak value of D3 is between 1610 cm⁻¹. -1 ~1640cm -1 Between; the peak value of D4 is at 1180 cm⁻¹ -1 ~1220cm -1 between.

[0060] I G / I D The degree of order of the carbon structure in the Raman spectrum is related to the degree of order in the carbon structure. In this application, I is used. G / I D Characterizing the degree of order in carbon structure, specifically, I G / I D Satisfying 0.4≤I G / I D ≤0.5, for example, I G / I D The values ​​can be 0.4, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, or 0.5.

[0061] I D3+D4 / I All Related to defects in the carbon structure, I is used in this application. D3+D4 / I All The degree to which carbon structural defects are characterized, specifically, I D3+D4 / I All Satisfying 0.35≤I D3+D4 / I All ≤0.42, for example, I D3+D4 / I All The values ​​can be 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, or 0.42.

[0062] I D3 / I Gˋ+D2+D3 Related to the degree of disorder in the carbon structure, this application uses I D3 / I Gˋ+D2+D3 Characterizing the degree of disorder in the carbon structure, specifically, I D3 / I Gˋ+D2+D3 Satisfy I D3 / I Gˋ+D2+D3 ≥0.14, for example, I D3 / I Gˋ+D2+D3The denominator can be 0.141, 0.142, 0.143, 0.144, 0.145, 0.146, 0.147, 0.148, 0.149, 0.150, 0.160, 0.170, or 0.180, preferably 0.18 ≥ 1. D3 / I Gˋ+D2+D3 ≥0.14.

[0063] The carbon material structure used in the negative electrode of sodium-ion batteries meets the above requirements, which is beneficial to improving reversible capacity, first-cycle discharge specific capacity and rate performance.

[0064] In this application, the peak value of G is usually between 1580cm and 1620cm, the peak value of D is usually between 1300cm and 1400cm, and the Gˋ peak is obtained by deconvolution of the G peak.

[0065] In an optional embodiment, the carbon material satisfies at least one of the following characteristics ai:

[0066] ad 002 The wavelength range is 0.36nm-0.39nm, for example, it can be 0.36nm, 0.365nm, 0.37nm, 0.375nm, 0.38nm, 0.385nm, or 0.39nm; d can be appropriately increased. 002 This helps reduce sodium ion diffusion resistance and provides more active sites, which is beneficial for sodium ion insertion and extraction, thus helping to increase sodium storage capacity. However, d 002 Excessive size can lead to a decrease in structural stability, electronic conductivity, and cycle stability.

[0067] b. Lc is 1.20nm-1.4nm, for example, it can be 1.20nm, 1.25nm, 1.30nm, 1.35nm, or 1.40nm; Lc is related to the crystallinity of the material. Within a reasonable range, Lc is beneficial to balance electronic conductivity while providing sufficient sodium storage sites.

[0068] c.Lc / d 002 The range is 3.35-3.65, for example, it can be 3.35, 3.40, 3.45, 3.50, 3.55, 3.60, 3.65; Lc / d 002 Reducing the sodium storage capacity can improve sodium storage capacity, but it can also lead to a decrease in electronic conductivity and rate performance.

[0069] d. The closed-pore ratio is 40%-65%, for example, it can be 40%, 45%, 50%, 55%, 60%, 65%. Reducing the closed-pore ratio is beneficial to increasing the number of effective sodium storage sites, thereby increasing the sodium storage capacity, but too low a closed-pore ratio will lead to a decrease in cycle performance.

[0070] e. The carbon material includes amorphous carbon;

[0071] f. Reversible specific capacity > 300mAh / g, for example, 300mAh / g, 305mAh / g, 310mAh / g, 315mAh / g, 320mAh / g;

[0072] h. The first discharge capacity is >320mAh / g, for example, it can be 320mAh / g, 330mAh / g, 340mAh / g, 350mAh / g, or 360mAh / g;

[0073] i. First-efficacy > 90%, for example, 90%, 91%, 92%, 93%, 94%.

[0074] This invention also provides a method for preparing the carbon material for the sodium-ion battery negative electrode described in the foregoing embodiments, comprising:

[0075] The slurry containing raw coal powder is subjected to flotation to obtain floating matter and settling matter;

[0076] The floating material is acid-washed to obtain deashed floating material;

[0077] The deashed floating material is subjected to pre-oxidation, steam activation and calcination in sequence to obtain the carbon material.

[0078] In this application, the floating material mainly consists of vitrinite and a small amount of chitinite. The vitrinite and chitinite have high volatile matter content and binding properties, and are chemically reactive, thus referred to as the active components. The sinking material mainly consists of inert matter, which has high thermal stability and aromatization, and is referred to as the inert components. The carbon material I obtained from the floating material after acid washing, pre-oxidation, steam activation, and calcination... G / I D I D3+D4 / I All and I D3 / I Gˋ+D2+D3 Meeting the aforementioned requirements is conducive to increasing capacity.

[0079] The raw coal powder in this application can be low-rank coal, which is obtained by screening according to the national standard GB / T477-2008 "Coal Screening Test Method" and then subjected to flotation.

[0080] In an optional embodiment, the particle size of the raw coal powder is less than 200 mesh;

[0081] And / or, in the flotation step, the ratio of raw coal powder to water in the slurry is 1g:(15-25)cm³. 3 ;

[0082] And / or, the slurry further includes a collector and / or a foaming agent;

[0083] And / or, in the flotation step, the enrichment rate of the floating material is 60%-80%, and the enrichment rate of the sinking material is 10%-40%.

[0084] The enrichment content can be determined using a heavy liquid separation method. Specifically, ZnCl2 solution is prepared according to the specific gravity liquid standard in the "Coal Industry Standard Compilation," and enrichment rates are measured using solutions with different specific gravities. The enrichment rate of the floating matter (vitrinite) is 60-80%, while the enrichment rate of the settling matter (inertite) is 10-40%. Vitrinite-based hard carbon, due to its richer graphitic microcrystalline structure and C=O content, exhibits superior reversible capacity, ICE (internal capacity), and rate performance in carbon materials. Impurities in the vitrinite intermediates are the inertite and chitinous groups that were not completely separated. The chitinous group, due to its low content and decomposition into visible oil-like liquids and volatile gases during carbonization, has little impact on the negative electrode material. The inertite group, being more difficult to graphitize, requires higher temperatures to achieve sodium storage performance and has a relatively large specific surface area; therefore, its content should be minimized.

[0085] In an optional embodiment, the collector is selected from at least one of oleic acid, hexadecyltrimethylammonium bromide, and sodium dodecyl sulfate; but is not limited to the above-mentioned substances, any substance that can perform the same function is acceptable;

[0086] And / or, the content of the collector in the slurry is 0.25 g / L-0.3 g / L;

[0087] And / or, the foaming agent includes one or more of n-octanol, sec-octanol, cyclohexanol, pine oil, industrial fusel oil or methyl isobutyl methanol; but is not limited to these, any substance that can perform the same function may be used.

[0088] And / or, the foaming agent content in the slurry is 0.08 g / L-0.1 g / L.

[0089] The proper setting of the types and amounts of collectors and frothers is beneficial to improving flotation efficiency and reducing flotation costs while obtaining the target floating material.

[0090] In an optional embodiment, the pickling includes sequentially performing hydrochloric acid washing and hydrofluoric acid washing on the floating material;

[0091] And / or, after the hydrochloric acid wash and hydrofluoric acid wash, the floating matter is washed with deionized water until neutral.

[0092] Hydrochloric acid washing and hydrofluoric acid washing of the floating material can remove the minerals mixed in with the floating material and reduce the impact of mineral residue on the performance of the negative electrode material.

[0093] In an optional embodiment, the concentration of the hydrochloric acid solution used for hydrochloric acid washing is 3 mol / L-7 mol / L, for example, it can be 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, 6 mol / L, 6.5 mol / L, or 7 mol / L; the amount of hydrochloric acid solution used per gram of floating matter in the hydrochloric acid washing step is less than 10 mL, for example, it can be 10 mL, 9 mL, 8 mL, 7 mL, 6 mL, 5 mL, 4 mL, 3 mL, 2 mL, or 1 mL;

[0094] And / or, the concentration of the hydrofluoric acid solution used for hydrofluoric acid pickling is 35wt% to 45wt%, for example, it can be 35wt%, 37wt%, 39wt%, 40wt%, 42wt%, 44wt%, or 45wt%; the amount of hydrofluoric acid solution used per gram of floating matter in the hydrofluoric acid pickling step is less than 10mL, for example, it can be 10mL, 9mL, 8mL, 7mL, 6mL, 5mL, 4mL, 3mL, 2mL, or 1mL.

[0095] Adjusting the concentration and dosage of acid solution appropriately can improve the removal effect of minerals. It should be noted that, if necessary, the number of acid washing cycles and the amount of acid solution can be increased to improve the removal efficiency of minerals, but this will result in a decrease in efficiency or an increase in acid loss.

[0096] In an optional embodiment, the pre-oxidation temperature is 250℃-300℃, for example, 250℃, 260℃, 270℃, 280℃, 290℃, or 300℃; the time is 3h-6h, for example, 3h, 4h, 5h, or 6h; the atmosphere is an oxidizing atmosphere, such as at least one of air or oxygen; and some organic matter and other impurities can be removed during the pre-oxidation step.

[0097] And / or, the activation temperature is 900℃-950℃, for example, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃; the time is 2h-6h, for example, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h.

[0098] The activation method can be one or more of physical and chemical activation. For physical activation, the activating gas can be at least one of water vapor and carbon dioxide, with a flow rate of 0.1 L / min to 2 L / min, for example, 0.1 L / min, 0.3 L / min, 0.5 L / min, 1 L / min, 1.5 L / min, or 2 L / min. For chemical activation, the activating agent is selected from at least one of KOH, NaOH, phosphoric acid, and potassium bicarbonate, with an addition amount of 5 wt% to 40 wt% of the pre-oxidized, deashed, and floated material, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%. During the activation process, it is necessary to control the activation temperature, time, and gas flow rate to adjust the carbon material structure while controlling the closed-pore ratio, avoiding an excessively low closed-pore ratio due to too many open pores that cannot be effectively closed during activation.

[0099] It should be noted that when physical activation is used in the activation step, the activation gas reacts with carbon in the coal: C + H₂O = CO + H₂ or CO₂ + C = 2CO. This not only affects the material structure but also generates a well-developed porous structure. Further roasting causes the carbon layer to twist, forming a closed porous structure, which can then be used to generate Na₂O. + The increased storage of Na+ increases the number of active sites, which is beneficial for Na+. + The de-embedding process can help increase capacity.

[0100] And / or, the roasting temperature is 1200℃-1300℃, for example, 1200℃, 1220℃, 1240℃, 1260℃, 1280℃, or 1300℃; the time is 2h-4h, for example, 2h, 3h, or 4h. The roasting process affects the degree of carbonization. Generally, the higher the carbonization temperature and the longer the time, the more beneficial it is to improving the degree of carbonization.

[0101] It should be noted that this application starts from the perspective of organic microstructure, uses heavy liquid centrifugation to separate and enrich the components of coal and rock, and uses pre-oxidation and non-alkali activation methods to obtain high-capacity, low-impurity coal-based hard carbon anode materials. The preparation process is simple, the process conditions are relatively mild, avoids excessive corrosive activation (such as alkaline solutions), is environmentally friendly, and is suitable for large-scale promotion.

[0102] The present invention also provides a negative electrode sheet comprising the carbon material described in the foregoing embodiments.

[0103] This invention also provides a sodium-ion battery, including the negative electrode sheet described in the foregoing embodiments.

[0104] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0105] Terminology Explanation

[0106] Mad refers to moisture (air-dried basis), Ad refers to ash (dried anhydrous basis), Vdaf refers to volatile matter (dried anhydrous basis), and FCad refers to fixed carbon (dried anhydrous basis). These various basis values ​​are based on the proportions of moisture, ash, volatile matter, and fixed carbon in different states of the material, which are better used in industry to measure the quality of the material. In elemental analysis, d refers to the mass fraction of the element in the dry basis.

[0107] Test Method Description

[0108] 1. Pore characteristic parameters: The specific surface area and pore volume of the material were determined by low-temperature nitrogen adsorption using a Microlithic Sasap 2020 fully automated physical adsorption instrument in the United States. The test conditions were: adsorption temperature -195.8℃ (77.35K), degassing temperature 150℃, degassing time 6h, specific surface area analysis method BET method, and pore size analysis model BJH model.

[0109] 2. XRD and Raman Testing: The XRD instrument used was a Beijing Purkinje MSALXD-3 X-ray powder diffractometer. The scanning range was 12-65°; the scanning speed was 2° / min; the step size was 0.02°; and the incident wavelength was λ = 1.5406. The samples were ground and sieved through a mesh smaller than 100 mesh, then immediately placed in a glass slide on a sample holder and sent to the XRD instrument for XRD experiments. Laser Raman spectroscopy (LRS) characterization of the samples was performed on an In-ViaQontor laser microconfocal Raman spectrometer (Renishaw, UK), using a laser wavelength of 532 nm. A 532 nm laser with a laser power of 5 mW was used, the integration time was 2 s, and the number of integrations was 10.

[0110] 3. XRD crystallographic parameters: Two large "bun-shaped" diffraction peaks are observed in the 15-55° range, corresponding to the 002 and 100 peaks, respectively. (The 002 peak of natural graphite is located at 26.6°). To compare the crystallographic structure of the residual carbon material, the 002 and 100 peaks in the 12-35° and 35-50° diffraction angle bands were fitted using Origin. For more accurate comparison and to reduce errors, baseline subtraction was first performed on the 12-65° data, and then the 002 and 100 peaks were fitted using peak fitting. The specific crystallographic structure information of the sample was calculated according to Bragg's law and Scherrer's law.

[0111] The calculation formula is as follows:

[0112] La=k1λ / (β 100 cosθ 100 )

[0113] Lc=k2λ / (β 002 cosθ 002 )

[0114] d 002 =λ2sinθ 002

[0115] In the formula: d 002 Lc is the distance between single layers of the microcrystalline structure; La is the stacking height of the microcrystalline layers; θ is the diameter of the microcrystalline structure. 002 θ 100 β is the Bragg diffraction angle. 002 β 100 λ is the full width at half maximum (FWHM); λ is the X-ray wavelength (nm); k is the shape factor, k1 = 1.84, k2 = 0.94.

[0116] 4. Raman crystallographic parameters: First-order region (800-2000 cm⁻¹) in the Raman spectrum of carbonaceous materials. -1 The Raman spectrum of coal exhibits two distinct overlapping bands, referred to as the D and G bands. Due to the overlap between the D and G bands, using only the D and G bands in the Raman spectrum leads to the loss or obsolescence of characteristic information of highly disordered carbonaceous materials. Therefore, further deconvolution (peak fitting) of the Raman spectrum of coal is required to obtain hidden information about the skeletal carbon structure in the overlapping region. Among various methods, the Raman spectra of carbonaceous materials have first-order and second-order bands. Further analysis of the first-order bands can typically divide them into characteristic peaks in the D1–D4 and G bands. Applying Origin 2016 to fit the Raman spectrum in the 800–2000 cm⁻¹ range... -1 The best fit is obtained by deconvolving the Raman spectrum between the peaks into four Lorentz peaks (D1, D2, D4, G) and one D3 Gaussian peak, as detailed in Table 1.

[0117] Table 1. Definition of Raman anti-revolution peak / bandwidth allocation

[0118]

[0119]

[0120] 5. Electrochemical performance testing of materials:

[0121] According to the mass ratio of negative electrode material:SP:CMC:SBR = 94:2:1.5:2.5, the negative electrode material, SP, CMC, and SBR were weighed separately and mixed evenly in deionized water to prepare a slurry. The uniformly mixed slurry was coated onto an aluminum foil current collector and baked in an oven at 80℃ for 1 hour. After cooling to room temperature, the roller spacing was adjusted to roll the electrode sheet. The rolled electrode sheet was cut into small round pieces with a diameter of 14mm and weighed as m1. Similarly, the aluminum foil current collector was cut into aluminum foil round pieces with a diameter of 14mm and weighed as m2. Wherein (m1-m2)*0.94 is the mass of the active material, denoted as m3. The weighed small discs were then vacuum-dried in an 80℃ oven for 12 hours, and then transferred to a glove box. Using sodium discs as the counter and auxiliary electrodes (electrolyte 1M NaPF6 / EC:DMC:DEC = 3:2:2) and a fiber diaphragm as the separator, sodium-ion coin cells were assembled in a glove box with oxygen and water contents both less than 0.01ppm. After standing for 12 hours, the electrochemical performance was tested under constant current on the Wuhan Landian Battery Testing System.

[0122] The testing method adopted the first-efficiency test procedure: 2 hours of rest, followed by discharge at 0.1C to 0.000V, 0.08C to 0.000V, 0.05C to 0.000V, and 0.02C to 0.000V, then 5 minutes of rest, followed by charging at 0.1C to 2.0V, and then 5 minutes of rest. Cycle rate performance testing mainly employed different discharge test methods. At 25℃, each battery was charged to 2.0V at 0.1C and discharged to 0V at 0.1C for three full charge-discharge cycles. This was then repeated sequentially at 0.2C, 0.5C, 0.2C, and 0.1C, with the number of cycles and the corresponding battery capacity recorded.

[0123] Example 1

[0124] This embodiment provides a carbon anode material, specifically including the following steps:

[0125] S1: After the raw coal SY is naturally dried, it is coarsely crushed and ground, and then screened according to the national standard GB / T477-2008 "Coal Screening Test Method" to obtain the flotation sample by passing through a 200-mesh sieve.

[0126] S2: Mix the original flotation sample with water at a ratio of 50g:1000cm³. 3 The mixture was mixed in proportion, and a measured amount of collector was added and stirred for 1 minute during flotation, followed by a measured amount of frother. The floating foam and settling matter were collected, filtered, and dried to obtain vitrinite-enriched fraction SY-RV1 and inertinite-enriched fraction SY-RI1 (wherein, the collector was oleic acid, and the frother was n-octanol, with dosages of 0.3 g / L and 0.1 g / L, respectively). SEM images of raw coal SY, vitrinite-enriched fraction SY-RV1, and inertinite-enriched fraction SY-RI1 are shown below. Figure 1 As shown in Table 2, the basic data is as follows.

[0127] S3: The obtained vitrinite enrichment SY-RV1 was placed in a 5 mol / L HCl solution (ratio 1g solid sample: 10mL acid solution, the same below), and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then placed in 40wt% HF and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then dried at 70℃. After drying, it was cooled to room temperature and dried to obtain the deashed sample SY-RVRC1.

[0128] S4: The prepared deashed sample was placed in a tube furnace and heated to 275℃ for pre-oxidation with air for 3 hours. Then, it was activated in a small rotary kiln at 915℃ for 4 hours with steam introduced at 0.5 L / min. Finally, it was calcined at 1250℃ for 3 hours under an inert nitrogen atmosphere to obtain the carbon anode material SY-RVC-H1. The XRD diffraction pattern and fitted peak diagram are shown below. Figure 2 As shown, the Raman spectrum is as follows Figure 3 As shown, the Raman fitting peaks are as follows Figure 4 As shown.

[0129] Table 2

[0130]

[0131] Example 2

[0132] This embodiment provides a carbon anode material, specifically including the following steps:

[0133] S1: After the raw coal SY is naturally dried, it is coarsely crushed and ground, and then screened according to the national standard GB / T477-2008 "Coal Screening Test Method" to obtain the flotation sample by passing through a 200-mesh sieve.

[0134] S2: Mix the original flotation sample with water at a ratio of 40g:1000cm³. 3 The mixture was mixed in proportion, and a certain amount of collector was added and stirred for 1 minute during the flotation process, followed by a certain amount of frother. The floating foam and the sediment were collected, filtered, and dried to obtain vitrinite enrichment SY-RV2 and inertinite enrichment SY-RI2 (wherein, the collector was oleic acid and the frother was n-octanol, with dosages of 0.3 g / L and 0.1 g / L, respectively).

[0135] S3: The obtained vitrinite enrichment SY-RV2 was placed in 5.5 mol / L HCl solution (ratio 1g solid sample: 10mL acid solution, the same below), and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then placed in 40wt% HF and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then dried at 70℃. After drying, it was cooled to room temperature and dried to obtain the deashed sample SY-RVRC2.

[0136] S4: The prepared deashed sample was placed in a tube furnace, heated to 290℃ and pre-oxidized with air for 4 hours. Then, it was activated at 950℃ for 2.5 hours in a small rotary furnace by introducing water vapor at 1L / min. Finally, it was calcined at 1280℃ for 2.5 hours under an inert atmosphere of nitrogen to obtain the carbon anode material SY-RVC-H2.

[0137] Example 3:

[0138] This embodiment provides a carbon anode material, specifically including the following steps:

[0139] S1: After the raw coal SY is naturally dried, it is coarsely crushed and ground, and then screened according to the national standard GB / T477-2008 "Coal Screening Test Method" to obtain the flotation sample by passing through a 200-mesh sieve.

[0140] S2: Mix the original flotation sample with water at a ratio of 40g:1000cm³. 3 The mixture was mixed in proportion, and a certain amount of collector was added and stirred for 1 minute during the flotation process, followed by a certain amount of frother. The floating foam and the sediment were collected, filtered, and dried to obtain vitrinite enrichment SY-RV3 and inertinite enrichment SY-RI3 (wherein, the collector was oleic acid, and the frother was n-octanol, with dosages of 0.25 g / L and 0.08 g / L, respectively).

[0141] S3: The obtained vitrinite enrichment SY-RV3 was placed in 4 mol / L HCl solution (ratio 1g solid sample: 10mL acid solution, the same below) and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral and then placed in 40wt% HF and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral and then dried at 70℃. After drying, it was cooled to room temperature and dried to obtain the deashed sample SY-RVRC3.

[0142] S4: The prepared deashed sample was placed in a tube furnace, heated to 275℃ and pre-oxidized with air for 3 hours. Then, it was activated at 935℃ for 3 hours in a small rotary furnace by introducing water vapor at 0.8 L / min. Finally, it was calcined at 1200℃ for 4.5 hours under an inert atmosphere of nitrogen to obtain the carbon anode material SY-RVC-H3.

[0143] Comparative Example 1:

[0144] This comparative example provides a carbon anode material. The difference in processing technology from Example 1 is that the flotation in step S2 is natural flotation.

[0145] S1: Raw coal SY is naturally dried, then coarsely crushed and ground, and then screened according to the national standard GB / T477-2008 "Coal Screening Test Method" to obtain the original sample by passing through a 200-mesh sieve.

[0146] S2: Mix the original flotation sample with water at a ratio of 50g:1000cm³. 3 The mixture was mixed in proportion, filtered, and dried to obtain a mixture of floating matter SY-RV4 and sinking matter SY-RI4.

[0147] S3: The obtained floating matter SY-RV4 was placed in a 5 mol / L HCl solution (ratio 1g solid sample: 10mL acid solution, the same below), and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then placed in 40wt% HF and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then dried at 70℃. After drying, it was cooled to room temperature and dried to obtain the deashed sample SY-RVRC4.

[0148] S4: The prepared deashed sample was placed in a tube furnace, heated to 275℃ and pre-oxidized with air for 3 hours. Then, it was activated at 915℃ for 4 hours in a small rotary furnace by introducing water vapor at 0.5L / min. Finally, it was calcined at 1250℃ for 3 hours under an inert atmosphere of nitrogen to obtain the carbon anode material SY-RVC-H4.

[0149] Comparative Example 2:

[0150] This comparative example provides a carbon anode material. The difference in processing technology from Example 1 is that the anode raw material is changed from vitrinite-enriched SY-RV1 to inertite-enriched SY-RI1.

[0151] S1: After the raw coal SY is naturally dried, it is coarsely crushed and ground, and then screened according to the national standard GB / T477-2008 "Coal Screening Test Method" to obtain the flotation sample by passing through a 200-mesh sieve.

[0152] S2: Mix the original flotation sample with water at a ratio of 50g:1000cm³. 3 The mixture was mixed in proportion, and a certain amount of collector was added and stirred for 1 minute during the flotation process, followed by a certain amount of frother. The floating foam and the sediment were collected, filtered, and dried to obtain vitrinite enrichment SY-RV1 and inertinite enrichment SY-RI1 (wherein, the collector was oleic acid and the frother was n-octanol, with dosages of 0.3 g / L and 0.1 g / L, respectively).

[0153] S3: The inert group enrichment SY-RI1 was placed in 5 mol / L HCl solution (ratio 1g solid sample: 10mL acid solution, the same below) and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral and then placed in 40wt% HF and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral and then dried at 70℃. After drying, it was cooled to room temperature and dried to obtain the deashed sample SY-RIRC1.

[0154] S4: The prepared deashed sample was placed in a tube furnace and heated to 275℃ for pre-oxidation with air for 3 hours. Then, it was activated in a small rotary kiln at 915℃ for 4 hours with steam introduced at 0.5 L / min. Finally, it was calcined at 1250℃ for 3 hours under an inert nitrogen atmosphere to obtain the carbon anode material SY-RIC-H1. The Raman spectrum is shown below. Figure 3 As shown.

[0155] Comparative Example 3:

[0156] This comparative example provides a carbon anode material. The difference in processing technology from Example 1 is that it is directly carbonized without acid washing and deashing.

[0157] S1: After the raw coal SY is naturally dried, it is coarsely crushed and ground, and then screened according to the national standard GB / T477-2008 "Coal Screening Test Method" to obtain the flotation sample by passing through a 200-mesh sieve.

[0158] S2: Mix the original flotation sample with water at a ratio of 50g:1000cm³. 3 The mixture was mixed in proportion, and a certain amount of collector was added and stirred for 1 minute during the flotation process, followed by a certain amount of frother. The floating foam and the sediment were collected, filtered, and dried to obtain vitrinite enrichment SY-RV1 and inertinite enrichment SY-RI1 (wherein, the collector was oleic acid and the frother was n-octanol, with dosages of 0.3 g / L and 0.1 g / L, respectively).

[0159] S3: The obtained vitrinite enrichment SY-RI1 was placed in a tube furnace, heated to 275℃ and pre-oxidized with air for 3h, then activated at 915℃ for 4h by introducing water vapor at 0.5L / min in a small rotary furnace, and finally calcined at 1250℃ for 3h under an inert atmosphere of nitrogen to obtain carbon anode material SY-RVC-H5.

[0160] Comparative Example 4:

[0161] This comparative example provides a carbon anode material. The difference in processing technology from Example 1 is that water vapor is not introduced for activation in step S4.

[0162] S1: After the raw coal SY is naturally dried, it is coarsely crushed and ground, and then screened according to the national standard GB / T477-2008 "Coal Screening Test Method" to obtain the flotation sample by passing through a 200-mesh sieve.

[0163] S2: Mix the original flotation sample with water at a ratio of 50g:1000cm³. 3 The mixture was mixed in proportion, and a certain amount of collector was added and stirred for 1 minute during the flotation process, followed by a certain amount of frother. The floating foam and the sediment were collected, filtered, and dried to obtain vitrinite enrichment SY-RV1 and inertinite enrichment SY-RI1 (wherein, the collector was oleic acid and the frother was n-octanol, with dosages of 0.3 g / L and 0.1 g / L, respectively).

[0164] S3: The obtained vitrinite enrichment SY-RV1 was placed in a 5 mol / L HCl solution (ratio 1g solid sample: 10mL acid solution, the same below), and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then placed in 40wt% HF and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then dried at 70℃. After drying, it was cooled to room temperature and dried to obtain the deashed sample SY-RVRC1.

[0165] S4: The deashed sample was placed in a tube furnace, heated to 275°C and pre-oxidized with air for 3 hours, and then calcined at 1250°C under an inert nitrogen atmosphere for 3 hours to obtain carbon anode material SY-RVC-H6.

[0166] Comparative Example 5:

[0167] This comparative example provides a carbon anode material. The difference between the processing technology and that of Example 1 is that the final carbonization degree in S4 is higher.

[0168] S1: After the raw coal SY is naturally dried, it is coarsely crushed and ground, and then screened according to the national standard GB / T477-2008 "Coal Screening Test Method" to obtain the flotation sample by passing through a 200-mesh sieve.

[0169] S2: Mix the original flotation sample with water at a ratio of 50g:1000cm³. 3 The mixture was mixed in proportion, and a certain amount of collector was added and stirred for 1 minute during the flotation process, followed by a certain amount of frother. The floating foam and the sediment were collected, filtered, and dried to obtain vitrinite enrichment SY-RV1 and inertinite enrichment SY-RI1 (wherein, the collector was oleic acid and the frother was n-octanol, with dosages of 0.3 g / L and 0.1 g / L, respectively).

[0170] S3: The obtained vitrinite enrichment SY-RV1 was placed in a 5 mol / L HCl solution (ratio 1g solid sample: 10mL acid solution, the same below), and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then placed in 40wt% HF and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then dried at 70℃. After drying, it was cooled to room temperature and dried to obtain the deashed sample SY-RVRC1.

[0171] S4: The prepared deashed sample was placed in a tube furnace, heated to 275℃ and pre-oxidized with air for 3 hours. Then, it was activated at 915℃ for 4 hours in a small rotary furnace by introducing water vapor at 0.5L / min. Finally, it was calcined at 1350℃ for 5 hours under an inert atmosphere of nitrogen to obtain the carbon anode material SY-RVC-H7.

[0172] Example 4:

[0173] This embodiment provides a carbon anode material. The difference between the processing technology and that of Embodiment 1 is that S4 has a lower degree of carbonization.

[0174] S1: After the raw coal SY is naturally dried, it is coarsely crushed and ground, and then screened according to the national standard GB / T477-2008 "Coal Screening Test Method" to obtain the flotation sample by passing through a 200-mesh sieve.

[0175] S2: Mix the original flotation sample with water at a ratio of 50g:1000cm³. 3 The mixture was mixed in proportion, and a certain amount of collector was added and stirred for 1 minute during the flotation process, followed by a certain amount of frother. The floating foam and the sediment were collected, filtered, and dried to obtain vitrinite enrichment SY-RV1 and inertinite enrichment SY-RI1 (wherein, the collector was oleic acid and the frother was n-octanol, with dosages of 0.3 g / L and 0.1 g / L, respectively).

[0176] S3: The obtained vitrinite enrichment SY-RV1 was placed in a 5 mol / L HCl solution (ratio 1g solid sample: 10mL acid solution, the same below), and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then placed in 40wt% HF and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then dried at 70℃. After drying, it was cooled to room temperature and dried to obtain the deashed sample SY-RVRC1.

[0177] S4: The prepared deashed sample was placed in a tube furnace, heated to 275℃ and pre-oxidized with air for 3 hours. Then, it was activated at 915℃ for 4 hours in a small rotary furnace by introducing water vapor at 0.5L / min. Finally, it was calcined at 1200℃ for 2 hours under an inert atmosphere of nitrogen to obtain the carbon anode material SY-RVC-H8.

[0178] Example 5:

[0179] This embodiment provides a carbon anode material. The difference in processing technology from that of Embodiment 1 is: S4, increasing the degree of water vapor activation.

[0180] S1: After the raw coal SY is naturally dried, it is coarsely crushed and ground, and then screened according to the national standard GB / T477-2008 "Coal Screening Test Method" to obtain the flotation sample by passing through a 200-mesh sieve.

[0181] S2: Mix the original flotation sample with water at a ratio of 50g:1000cm³. 3 The mixture was mixed in proportion, and a certain amount of collector was added and stirred for 1 minute during the flotation process, followed by a certain amount of frother. The floating foam and the sediment were collected, filtered, and dried to obtain vitrinite enrichment SY-RV1 and inertinite enrichment SY-RI1 (wherein, the collector was oleic acid and the frother was n-octanol, with dosages of 0.3 g / L and 0.1 g / L, respectively).

[0182] S3: The obtained vitrinite enrichment SY-RV1 was placed in a 5 mol / L HCl solution (ratio 1g solid sample: 10mL acid solution, the same below), and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then placed in 40wt% HF and stirred at 80℃ for 6h. After filtration, it was washed with deionized water until neutral, and then dried at 70℃. After drying, it was cooled to room temperature and dried to obtain the deashed sample SY-RVRC1.

[0183] S4: The prepared deashed sample was placed in a tube furnace, heated to 275℃ and pre-oxidized with air for 3 hours. Then, it was activated at 915℃ for 6 hours in a small rotary furnace by introducing water vapor at 1L / min. Finally, it was calcined at 1250℃ for 2 hours under an inert atmosphere of nitrogen to obtain the carbon anode material SY-RVC-H9.

[0184] The microcrystal parameters of the samples prepared in the above embodiments and comparative examples are shown in Table 3.

[0185] Table 3

[0186]

[0187] The Raman carbon structure parameters of the samples prepared in the above embodiments and comparative examples are shown in Table 4, and the electrical properties are shown in Table 4 and... Figure 5-6 As shown.

[0188] Table 4

[0189]

[0190]

[0191] From Tables 3 and 4 above and Figure 5 It can be seen that when the prepared carbon anode material simultaneously satisfies characteristic ① 0.4≤I G / I D ≤0.5, Special ② 0.35≤I D3+D4 / I All ≤0.42 and I D3 / I G`+D2+D3 When the value is ≥0.14, the reversible specific capacity, first-cycle discharge specific capacity, and first-efficiency all show good performance. Compared with Examples 1-3, Examples 4 and 5 only satisfy characteristics ① and ② 0.35≤I. D3+D4 / I All ≤0.42 or I D3 / I G`+D2+D3 Although the reversible specific capacity, first-cycle discharge specific capacity and first-cycle efficiency are better than those of Examples 1-3, the difference is significant. ≥0.14

[0192] A comparison of Comparative Examples 1-2 with the Examples shows that the carbon anode materials prepared using raw coal or sediment as carbon raw materials cannot meet the requirements of this application, resulting in a significant reduction in reversible specific capacity, first-cycle discharge specific capacity, and first-cycle efficiency compared to Examples 4-5. A comparison of Comparative Examples 3-5 with Example 1 shows that the degree of acid washing, steam activation, and carbonization all affect the microstructure of the carbon material. Omission or improper setting of the degree of acid washing, steam activation, and carbonization will result in the obtained carbon anode materials failing to meet the requirements of this application, leading to a significant reduction in reversible specific capacity, first-cycle discharge specific capacity, and first-cycle efficiency compared to Examples 4-5.

[0193] from Figure 6 Analysis of the rate performance test results shows that, compared with the comparative example, the product obtained in the example exhibits better capacity retention under different charge and discharge currents, that is, the negative electrode material obtained by the preparation process provided in this application has good rate performance.

[0194] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A carbon material for the negative electrode of a sodium-ion battery, characterized in that, The Raman spectrum of the carbon material satisfies characteristics ① and characteristic ②: Feature ① 0.4≤I G / I D ≤0.5; Special expedition②0.35≤I D3+D4 / I All ≤0.42; sum I D3 / I G`+D2+D3 ≥0.14; Among them, I G I represents the area of ​​the G peak in the Raman spectrum. D I represents the area of ​​peak D in the Raman spectrum. D3+D4 To fit the total area of ​​peaks D3 and D4 in the Raman spectrum; I All To fit the total area of ​​the G', D1, D2, D3, and D4 peaks in the Raman spectrum; I D3 To fit the area of ​​the D3 peak in the Raman spectrum; I G`+D2+D3 To fit the total area of ​​the G', D2, and D3 peaks in the Raman spectrum; The fitted Raman spectrum was obtained by deconvolution of the Raman spectrum; the peak value of G' is at 1560 cm⁻¹. -1 ~1600cm -1 Between; the peak value of D1 is at 1330 cm⁻¹. -1 ~1370cm -1 Between; the peak value of D2 is at 1480 cm⁻¹. -1 ~1520cm -1 Between; the peak value of D3 is at 1610 cm⁻¹. -1 ~1640cm -1 Between; the peak value of D4 is at 1180 cm⁻¹. -1 ~1220cm -1 between; The carbon material has a closed-porosity of 40%-65%, and the preparation method of the carbon material includes: The slurry containing raw coal powder is subjected to flotation to obtain floating matter and settling matter. The floating matter is the vitrinite group and the settling matter is the inertite group. The floating material is acid-washed to obtain deashed floating material; The deashed floating material is subjected to pre-oxidation, activation and calcination in sequence to obtain the carbon material. The activation method is physical activation and the activation gas is water vapor.

2. The carbon material for the negative electrode of a sodium-ion battery according to claim 1, characterized in that, The carbon material satisfies at least one of the following characteristics: ad 002 The wavelength is 0.36 nm - 0.39 nm. b.Lc is 1.20 nm - 1.4 nm; c.Lc / d 002 The value is 3.35-3.65; d. The carbon material includes amorphous carbon; e. Reversible specific capacity > 300mAh / g; f. First-cycle discharge specific capacity > 320mAh / g; h. First-time efficacy > 90%.

3. A method for preparing a carbon material for a sodium-ion battery negative electrode as described in claim 1 or 2, characterized in that, include: The slurry containing raw coal powder is subjected to flotation to obtain floating matter and settling matter; The floating material is acid-washed to obtain deashed floating material; The deashed floating material is subjected to pre-oxidation, activation and calcination in sequence to obtain the carbon material.

4. The method for preparing carbon material for sodium-ion battery negative electrode according to claim 3, characterized in that, The particle size of the raw coal powder is less than 200 mesh; And / or, in the flotation step, the ratio of raw coal powder to water in the slurry is 1g:(15-25)cm³. 3 ; And / or, the slurry further includes a collector and / or a foaming agent; And / or, in the flotation step, the enrichment rate of the floating material is 60%-80%, and the enrichment rate of the sinking material is 10%-40%.

5. The method for preparing carbon material for sodium-ion battery negative electrode according to claim 4, characterized in that, The collector is selected from at least one of oleic acid, hexadecyltrimethylammonium bromide and sodium dodecyl sulfate; And / or, the content of the collector in the slurry is 0.25 g / L - 0.3 g / L; And / or, the foaming agent includes one or more of n-octanol, sec-octanol, cyclohexanol, pine oil, or methyl isobutyl methanol; And / or, the foaming agent content in the slurry is 0.08 g / L - 0.1 g / L.

6. The method for preparing carbon material for sodium-ion battery negative electrode according to claim 3, characterized in that, The pickling process includes sequential hydrochloric acid washing and hydrofluoric acid washing of the floating material. And / or, after the hydrochloric acid wash and hydrofluoric acid wash, the floating matter is washed with deionized water until neutral.

7. The method for preparing carbon material for sodium-ion battery negative electrode according to claim 6, characterized in that, The concentration of hydrochloric acid solution used for hydrochloric acid washing is 3 mol / L - 7 mol / L, and the amount of hydrochloric acid solution used per gram of floating matter in the hydrochloric acid washing step is less than 10 mL. And / or, the concentration of the hydrofluoric acid solution used for hydrofluoric acid washing is 35 wt%-45 wt%, and the amount of hydrofluoric acid solution used per gram of floating matter in the hydrofluoric acid washing step is less than 10 mL.

8. The method for preparing carbon material for sodium-ion battery negative electrode according to claim 3, characterized in that, The pre-oxidation temperature is 250℃-300℃, the time is 3h-6h, and the atmosphere is an oxidizing atmosphere; And / or, the activation temperature is 900℃-950℃, and the time is 2h-5h; And / or, the activation gas flow rate is 0.1 L / min - 2 L / min; And / or, the calcination temperature is 1200℃-1300℃, and the time is 2h-4h.

9. A negative electrode sheet, characterized in that, Includes the carbon material as described in claim 1 or 2.

10. A sodium-ion battery, characterized in that, Includes the negative electrode sheet as described in claim 9.

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