Amorphous carbon material and preparation method thereof, negative electrode and sodium ion battery

Abstract

The invention relates to an amorphous carbon material and a preparation method thereof, a negative electrode and a sodium ion battery. The value of ID / IG of a Raman spectrum of the amorphous carbon material is 0.93 to 1.2; the value of 100 * Lc * La / d002 of the amorphous carbon material is 1010 to 1200. When the amorphous carbon material is used as the negative electrode of the sodium-ion battery, the sodium-ion battery has relatively high capacity and first coulombic efficiency. The preparation method comprises the following steps: (1) performing crushing, purification treatment and pre-oxidation treatment on raw coal to obtain pre-oxidized coal; (2) mixing and extruding the pre-oxidized coal and asphalt to obtain a coal / asphalt mixture; and (3) carrying out carbonization treatment on the coal / asphalt mixture. The method is low in preparation cost and beneficial to large-scale production.

Description

Technical Field

[0001] This disclosure relates to the field of sodium-ion battery technology, specifically to an amorphous carbon material and its preparation method, a negative electrode, and a sodium-ion battery. Background Technology

[0002] The sodium-ion battery industry supply chain is currently incomplete, with the anode being a crucial missing link. There is an urgent need to develop low-cost, high-capacity anode materials for sodium-ion batteries. Coal, as an important fossil energy source in my country, boasts abundant reserves and wide distribution, making it a viable low-cost carbon source for anode materials. Furthermore, coals of different metamorphic degrees exhibit distinct structural characteristics, providing a reliable guarantee for the structural control of coal-based carbon materials.

[0003] The capacity and initial coulombic efficiency of anode materials prepared using coal in existing technologies still need to be further improved. Summary of the Invention

[0004] The purpose of this disclosure is to provide an amorphous carbon material and its preparation method, a negative electrode, and a sodium-ion battery. When the amorphous carbon material is used as the negative electrode of a sodium-ion battery, the sodium-ion battery exhibits high capacity and initial coulombic efficiency.

[0005] To achieve the above objectives, the first aspect of this disclosure provides an amorphous carbon material, wherein the Raman spectrum of the amorphous carbon material exhibits Ig... D / I G The value is 0.93~1.2; the amorphous carbon material is 100×L c ×L a / d 002 The value is 1010~1200.

[0006] Optionally, the Raman spectrum of the amorphous carbon material is I D / I G The value is 0.93~0.96.

[0007] A second aspect of this disclosure provides a method for preparing amorphous carbon materials, comprising the following steps: S1. The raw coal is crushed, purified, and pre-oxidized to obtain pre-oxidized coal, wherein the volatile matter content in the raw coal is 20-45% by weight. S2. The pre-oxidized coal and pitch are mixed and extruded to obtain a coal / pitch mixture; S3. Carbonize the coal / asphalt mixture.

[0008] Optionally, in step S1, the volatile matter content in the raw coal is 25-40% by weight. Optionally, the D of the raw coal obtained from the crushing process 50 The particle size is 5~20μm.

[0009] Optionally, in step S1, the purification process includes: sequentially subjecting the raw coal to alkaline treatment and acid treatment; Optionally, the alkaline treatment conditions include: an alkaline concentration of 10-80% by weight, a treatment temperature of 100-200°C, and a treatment time of 1-8 hours; preferably, the alkaline concentration is 40-60% by weight, the treatment temperature is 120-150°C, and the treatment time is 2-4 hours; the alkaline solution is selected from one or more of sodium hydroxide solution and potassium hydroxide solution. Optionally, the acid treatment conditions include: an acid concentration of 5-30% by weight, a treatment temperature of 50-120°C, and a treatment time of 1-8 hours; preferably, an acid concentration of 5-15% by weight, a treatment temperature of 60-80°C, and a treatment time of 2-4 hours; the acid is selected from one or more of HCl solution and H2SO4 solution.

[0010] Optionally, in step S1, the pre-oxidation treatment conditions include: a treatment temperature of 50~500℃ and a treatment time of 1~8h in an oxygen-containing atmosphere; the oxygen concentration in the oxygen-containing atmosphere is 10~30% by volume%. Preferably, the pre-oxidation treatment conditions include: a treatment temperature of 150~300℃ and a treatment time of 3~6h in an oxygen-containing atmosphere; the oxygen concentration in the oxygen-containing atmosphere is 15~20% by volume. Optionally, in the pre-oxidation treatment, the heating rate is 0.5~10℃ / min, preferably 1~5℃ / min.

[0011] Optionally, in step S2, the weight ratio of the pre-oxidized coal to the pitch is 1~99:1, preferably 19~99:1; Preferably, the softening point of the asphalt is above 250°C; Optionally, the asphalt is selected from one or more of petroleum asphalt, coal tar pitch, oxidized asphalt, and mesophase asphalt.

[0012] Optionally, in step S2, the conditions for the mixed extrusion treatment include: an extrusion temperature of 100~400℃, preferably 200~300℃, and a residence time of 30~300min, preferably 60~180min.

[0013] Optionally, in step S3, the carbonization treatment includes: subjecting the coal / asphalt mixture to pre-carbonization treatment and high-temperature carbonization treatment sequentially under an inert atmosphere; wherein the temperature of the high-temperature carbonization treatment is higher than the temperature of the pre-carbonization treatment; and the inert atmosphere is selected from one or more of nitrogen and argon. Preferably, the pre-carbonization treatment conditions include: under an inert atmosphere, a pre-carbonization temperature of 500~900℃ and a pre-carbonization time of 1~8h; preferably, a pre-carbonization temperature of 500~600℃ and a pre-carbonization time of 2~5h; optionally, the heating rate of the pre-carbonization treatment is 0.5~10℃ / min, preferably 1~5℃ / min. Preferably, the conditions for the high-temperature carbonization treatment include: under an inert atmosphere, the high-temperature carbonization temperature is 1000~1800℃, and the high-temperature carbonization time is 1~8h; preferably, the high-temperature carbonization temperature is 1200~1600℃, and the high-temperature carbonization time is 2~5h; optionally, the heating rate of the high-temperature carbonization treatment is 0.5~10℃ / min, preferably 1~5℃ / min.

[0014] The third aspect of this disclosure provides an amorphous carbon material prepared according to the method described in the second aspect of this disclosure.

[0015] A fourth aspect of this disclosure provides a negative electrode comprising the amorphous carbon material described in the first or third aspect of this disclosure.

[0016] This disclosure provides a fifth aspect of a sodium-ion battery, which includes the negative electrode described in the fourth aspect of this disclosure.

[0017] Through the above technical solution, this disclosure provides an amorphous carbon material and its preparation method, a negative electrode, and a sodium-ion battery. The amorphous carbon material has a unique microcrystalline structure, wherein I... D / I G The value is 0.93~1.2, 100×L c ×L a / d 002 The value is 1010~1200, which allows the amorphous carbon material to improve battery capacity and initial coulombic efficiency when used in sodium-ion battery anodes. The method for preparing amorphous carbon materials provided in this disclosure is simple. After purifying and pre-oxidizing raw coal, it is coated with pitch and then carbonized. The pitch coating can regulate the microcrystalline structure of the carbon material, thereby improving its application effect in sodium-ion battery anodes.

[0018] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 The Raman spectrum of the amorphous carbon material prepared in Example 1 of this disclosure; Figure 2 The image shows the XRD pattern of the amorphous carbon material prepared in Example 1 of this disclosure. Detailed Implementation

[0020] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0021] The first aspect of this disclosure provides an amorphous carbon material, wherein the Raman spectrum of the amorphous carbon material is I D / I G The value is 0.93~1.2; the amorphous carbon material is 100×L c ×L a / d 002 The value is 1010~1200.

[0022] This disclosure provides an amorphous carbon material with a unique microcrystalline structure, which enables the amorphous carbon material to improve battery capacity and first coulombic efficiency when used in the anode of sodium-ion batteries.

[0023] In this disclosure, I D / I G Indicates the peak intensity of D (I) D ) and G peak intensity (I G The ratio of (D peak) to (D peak) usually appears at about 1300 cm⁻¹. -1 Nearby, the G peak typically appears at approximately 1580 cm. -1 The location was nearby. The results were obtained using conventional Raman spectroscopy instruments and methods in this field.

[0024] In this disclosure, L c L a d 002 L represents the crystal parameters of graphite. a L represents the average size of the graphite crystal along the a-axis. c Let d be the thickness of the deposited material along the c-axis. 002 The distance between the graphite sheets is obtained by X-ray diffraction (XRD) technology.

[0025] In a preferred embodiment, the Raman spectrum of the amorphous carbon material has an I... D / I G The value is 0.93~0.96; it has the characteristics of I in this embodiment. D / I G Carbon materials have a superior microcrystalline structure, which leads to better improvement in battery capacity and initial coulombic efficiency in sodium-ion battery applications.

[0026] In one specific embodiment, the D of the amorphous carbon material 50 The particle size is 5~50μm, preferably 5~20μm.

[0027] The amorphous carbon material disclosed herein contains carbon and possibly trace impurity elements.

[0028] A second aspect of this disclosure provides a method for preparing amorphous carbon materials, comprising the following steps: S1. The raw coal is crushed, purified, and pre-oxidized to obtain pre-oxidized coal, wherein the volatile matter content in the raw coal is 20-45% by weight. S2. The pre-oxidized coal and pitch are mixed and extruded to obtain a coal / pitch mixture; S3. Carbonize the coal / asphalt mixture.

[0029] This disclosure provides a method for preparing amorphous carbon materials, which involves purifying and pre-oxidizing raw coal, then coating it with pitch and carbonizing it. The purification process helps reduce the ash content; the pre-oxidation process helps increase and regulate the content of oxygen-containing functional groups, thereby increasing sodium ion storage sites; and the pitch coating can regulate the microcrystalline structure of the carbon material to improve its application effect in sodium-ion battery anodes.

[0030] In one specific embodiment, in step S1, the volatile matter content in the raw coal is 25-40% by weight; optionally, the D50 particle size of the raw coal obtained by crushing is 5-20 μm.

[0031] In one embodiment, step S1 includes: subjecting the raw coal to alkali treatment and acid treatment in sequence; by purifying the raw coal with alkali and acid, the ash content is reduced, sodium storage sites are regulated, and battery safety is improved.

[0032] In a preferred embodiment, the alkaline treatment conditions include: an alkaline concentration of 10-80% by weight, a treatment temperature of 100-200°C, and a treatment time of 1-8 hours; preferably, the alkaline concentration is 40-60% by weight, the treatment temperature is 120-150°C, and the treatment time is 2-4 hours; the alkaline solution is selected from one or more of sodium hydroxide solution and potassium hydroxide solution. Optionally, the acid treatment conditions include: an acid concentration of 5-30% by weight, a treatment temperature of 50-120°C, and a treatment time of 1-8 hours; preferably, the acid concentration is 5-15% by weight, the treatment temperature is 60-80°C, and the treatment time is 2-4 hours; the acid is selected from one or more of HCl solution and H2SO4 solution. According to the process conditions in this embodiment, especially the preferred process conditions, a superior purification effect can be achieved.

[0033] In one embodiment, the pre-oxidation treatment conditions in step S1 include: a treatment temperature of 50-500°C and a treatment time of 1-8 hours in an oxygen-containing atmosphere; the oxygen concentration in the oxygen-containing atmosphere is 10-30% by volume; preferably, the treatment temperature is 150-300°C and the treatment time is 3-6 hours; the oxygen concentration in the oxygen-containing atmosphere is 10-20% by volume; the pre-oxidation treatment according to the process conditions of this embodiment, especially the preferred process conditions, can effectively regulate oxygen-containing functional groups and increase sodium ion storage sites.

[0034] In one specific embodiment, the heating rate in the pre-oxidation treatment is 0.5~10℃ / min, preferably 1~5℃ / min. Heating to the pre-oxidation temperature according to the heating conditions in this embodiment is more conducive to increasing the oxygen content, thereby increasing the number of sodium ion storage sites.

[0035] In one embodiment, in step S2, the weight ratio of the pre-oxidized coal to the asphalt is 1~99:1, preferably 19~99:1. Applying the asphalt coating according to the weight ratio specified in this embodiment achieves a superior microcrystalline structure control effect.

[0036] In one specific embodiment, the asphalt softening point is above 250°C; Optionally, the asphalt is selected from one or more of petroleum asphalt, coal tar pitch, oxidized asphalt, and mesophase asphalt. The asphalt used in this disclosure has a wide range of sources.

[0037] In one embodiment, the conditions for the mixed extrusion treatment in step S2 include: an extrusion temperature of 100~400℃, preferably 200~300℃; and a residence time of 30~300min, preferably 60~180min. Treatment according to the mixed extrusion conditions in this embodiment can achieve a better asphalt coating effect, thereby improving the performance of the resulting carbon material in the battery anode.

[0038] In one embodiment, step S3, the carbonization treatment includes: sequentially subjecting the coal / asphalt mixture to pre-carbonization treatment and high-temperature carbonization treatment, wherein the temperature of the high-temperature carbonization treatment is higher than the temperature of the pre-carbonization treatment; the inert atmosphere is selected from one or more of nitrogen and argon; this disclosure employs a two-stage carbonization treatment to carbonize the coal / asphalt mixture, which better controls the microcrystalline structure and improves the sodium storage performance.

[0039] In a preferred embodiment, the pre-carbonization treatment conditions include: under an inert atmosphere, a pre-carbonization temperature of 500~900℃ and a pre-carbonization time of 1~8h; preferably, the pre-carbonization temperature is 500~600℃ and the pre-carbonization time is 2~5h. The conditions for the high-temperature carbonization treatment include: under an inert atmosphere, the high-temperature carbonization temperature is 1000~1800℃, and the high-temperature carbonization time is 1~8h. Preferably, the high-temperature carbonization temperature is 1200~1600℃, and the high-temperature carbonization time is 2~5h. According to the process conditions in this embodiment, especially according to the preferred conditions, the amorphous carbon material obtained by carbonization has higher capacity and first coulombic effect in sodium-ion battery anode applications.

[0040] In a preferred embodiment, the heating rate of the pre-carbonization treatment is 0.5~10℃ / min, preferably 1~5℃ / min; the heating rate of the high-temperature carbonization treatment is 0.5~10℃ / min, preferably 1~5℃ / min. The heating rate in this embodiment, especially the preferred heating rate, is beneficial to enhance the coating uniformity, thereby improving the performance of amorphous carbon materials in battery applications.

[0041] The third aspect of this disclosure provides an amorphous carbon material prepared according to the method described in the second aspect of this disclosure.

[0042] A fourth aspect of this disclosure provides a negative electrode comprising the amorphous carbon material described in the first or third aspect of this disclosure.

[0043] In one specific embodiment, the negative electrode may also include other components, such as conductive agents and binders, and the content of each component is within the conventional content range in the art.

[0044] This disclosure provides a sodium-ion battery in a fifth aspect, comprising the negative electrode described in the fourth aspect of this disclosure. The sodium-ion battery provided by this disclosure can be composed of conventional battery components in the art.

[0045] The present disclosure is further described in detail below through examples. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the present disclosure are commercially available or can be prepared by existing methods.

[0046] The sample structure was characterized using a Bruker D8 Advance X-ray diffractometer (XRD) from Germany, with Cu Kα as the X-ray source. =1.54184Å). The formula for calculating the parameter is: , , Where θ 002 and θ 100 The peak positions and diffraction angles of the (002) peak and (100) peak in the XRD pattern are respectively, β 002 and β 100 These are the full width at half maximum (FWHM) values ​​of the (002) peak and the (100) peak in the XRD spectrum, respectively.

[0047] The Raman spectrometer used was a HORIBA LabRAM HR800 Raman spectrometer with a laser wavelength of 532 nm. D 50 The particle size was obtained by testing with a Malvern Mastersizer 2000 laser particle size analyzer from Malvern Instruments Ltd., UK.

[0048] Example 1 (1) Raw coal (volatile matter content of 34.6% by weight) is subjected to crushing, purification and pre-oxidation treatment to obtain pre-oxidized coal; wherein the D of the raw coal obtained by crushing is... 50 The particle size is 15 μm; the purification treatment conditions include: placing the crushed raw coal in a 50 wt% NaOH solution and treating it at 150℃ for 3 h (alkali treatment), and then treating it in a 10 wt% HCl solution at 70℃ for 3 h (acid treatment); the pre-oxidation treatment conditions include: treating it at 250℃ for 4 h in an oxygen-containing gas atmosphere (oxygen concentration of 20 vol%), with a heating rate of 5℃ / min; (2) The pre-oxidized coal and pitch are mixed and extruded to obtain a coal / pitch mixture; wherein the weight ratio of pre-oxidized coal to pitch is 19:1, the pitch is selected from petroleum pitch, and the softening point is 260℃; the conditions for mixed extrusion include: extrusion temperature of 200℃ and residence time in screw of 120min. (3) The coal / asphalt mixture is subjected to pre-carbonization treatment and high-temperature carbonization treatment in sequence; the conditions for pre-carbonization treatment include: under an inert atmosphere, the pre-carbonization temperature is 500℃, the pre-carbonization time is 2h, and the heating rate is 3℃ / min; the conditions for high-temperature carbonization treatment include: under an inert atmosphere, the high-temperature carbonization temperature is 1400℃, the high-temperature carbonization time is 2h, and the heating rate is 5℃ / min. In this embodiment, an amorphous carbon material was prepared. The Raman spectrum of this amorphous carbon material is shown in the following figure. Figure 1 As shown, at 1367cm -1 The peak intensity of the nearby D peak is 1047, and at 1587 cm⁻¹... -1 The peak intensity of the nearby G peak is 1114, and the calculated I... D / I G The value is 0.940; In the XRD spectrum of this amorphous carbon material, as shown... Figure 2 As shown, L a The value is 3.619 nm; L c The value is 1.142 nm; d 002 The value is 0.374 nm, and the calculated value is 100×L. c ×La / d 002 The value is 1105.

[0049] Example 2 This embodiment refers to the preparation method in Example 1, except that the volatile matter content of the raw coal used is 36.3% by weight, and the rest of the process is the same as in Example 1, to prepare amorphous carbon material.

[0050] Example 3 This embodiment refers to the preparation method in Example 1, except that the pre-oxidation temperature is 300℃, and the rest of the process is the same as in Example 1, to prepare amorphous carbon material.

[0051] Example 4 This embodiment refers to the preparation method in Example 1, except that the weight ratio of pre-oxidized coal to pitch is 99:1, and the rest of the process is the same as in Example 1, to prepare amorphous carbon material.

[0052] Example 5 This embodiment refers to the preparation method in Example 1, except that the high-temperature carbonization temperature used is 1600℃, and the rest of the process is the same as in Example 1, so as to prepare amorphous carbon material.

[0053] Example 6 This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that: The heating rate for the pre-oxidation treatment was 10℃ / min, and the rest of the process was the same as in Example 1, to prepare carbon materials.

[0054] Example 7 This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that: In the pre-oxidation treatment, the material was prepared by treating at 350°C for 8 hours in an oxygen-containing gas atmosphere (oxygen concentration of 20% by volume) at a heating rate of 5°C / min; the remaining process was the same as in Example 1.

[0055] Example 8 This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that: In the mixed extrusion process, the weight ratio of pre-oxidized coal to pitch is 1:1, and the remaining processes are the same as in Example 1, to prepare carbon materials.

[0056] Example 9 This embodiment refers to the preparation method in Example 1, but differs from Example 1 in that: The conditions for high-temperature carbonization included: under an inert atmosphere, a high-temperature carbonization temperature of 1000℃, a high-temperature carbonization time of 5h, and a heating rate of 5℃ / min; the remaining processes were the same as in Example 1, and carbon materials were prepared.

[0057] Comparative Example 1 This comparative example follows the preparation method in Example 1, except that the raw coal used has a volatile matter content of 46.8% by weight.

[0058] Comparative Example 2 This comparative example follows the preparation method in Example 1, but differs from Example 1 in that the volatile matter content of the raw coal used is 7.2% by weight.

[0059] Comparative Example 3 This comparative example follows the preparation method in Example 1, except that the volatile matter content of the raw coal used is 2.56% by weight.

[0060] Comparative Example 4 This comparative example follows the preparation method in Example 1, but differs from Example 1 in that: instead of mixing and extruding the pre-oxidized coal and pitch, the pre-oxidized coal is directly carbonized. The rest of the process is the same as in Example 1.

[0061] The amorphous carbon materials prepared using the above examples and comparative examples are I D / I G 100×L c ×L a / d 002 The data is listed in Table 1 below.

[0062] Table 1

[0063] The data in Table 1 shows that: In Comparative Examples 1-4, carbon materials were not prepared according to the method provided in this disclosure, and the resulting products had I D / I G 100×L c ×L a / d 002 The values ​​are all outside the range provided in this disclosure; in Examples 1-9, carbon materials were prepared according to the method provided in this disclosure, and the resulting products had I D / I G The value is in the range of 0.93 to 1.2, 100×L c ×L a / d 002The value is in the range of 1010~1200; furthermore, Examples 1~5 were prepared according to the preferred process conditions provided in this disclosure, and the resulting carbon material products have an I value. D / I G The value is preferably in the range of 0.93 to 0.96.

[0064] Test case This test example illustrates the application effect of the carbon materials prepared in the above embodiments and comparative examples as negative electrode materials in sodium-ion batteries.

[0065] The amorphous carbon material obtained in the examples and comparative examples was used as the negative electrode to prepare this sodium-ion battery according to conventional methods. The preparation process of a conventional coin cell battery is as follows: Amorphous carbon material, used as the negative electrode material, was mixed uniformly with conductive carbon black Super P and binder polyvinylidene fluoride (PVDF) at a mass ratio of 92:3:5. N-methylpyrrolidone (NMP) solvent was added, and the mixture was stirred to form a homogeneous negative electrode slurry. This slurry was then uniformly coated onto aluminum foil using a scraper and dried to obtain the negative electrode sheet. The resulting negative electrode sheet was punched into a 12mm diameter sheet and transferred to an MBraun 2000 glove box (Ar atmosphere, H2O and O2 concentrations less than 0.1 × 10⁻⁶). -6 The cells were assembled into coin cells using a sodium metal sheet as the reference electrode (vol%). The electrolyte was a 1M NaPF6 / (EC+DMC) solution, with EC:DMC = 1:1 (vol%). The counter electrode was a sodium sheet.

[0066] The battery capacity was tested using the CT2001A battery tester from Wuhan Landian Electronics Co., Ltd., with a charge / discharge current of 0.1C (1C=350mAh / g) and a voltage of 0~3V. The test results are listed in Table 2 below.

[0067] Table 2

[0068] According to the data in Tables 1 and 2: Compared with the carbon materials prepared in Comparative Examples 1-4, the amorphous carbon materials prepared in Examples 1-9 according to the method provided in this disclosure have a higher I content. D / I G The value is in the range of 0.93 to 1.2, 100×L c ×L a / d 002 The value is in the range of 1010~1200. The carbon materials obtained in Examples 1~9 are used as the negative electrode of sodium-ion batteries, and the sodium-ion batteries have higher capacity and first coulombic efficiency. Comparing Examples 1-5 with Example 6, it can be seen that in the pre-oxidation treatment of Examples 1-5, a preferred heating rate was used, and the carbon material products obtained in Examples 1-5 had a higher I... D / I G The value is within the preferred range, and it has higher capacity and first coulombic efficiency when used in sodium-ion battery applications; Comparing Examples 1-5 with Example 7, it can be seen that Examples 1-5 used preferred reaction temperatures and times in the pre-oxidation treatment, and the carbon material products obtained in Examples 1-5 had higher I... D / I G The value is within the preferred range, and it has higher capacity and first coulombic efficiency when used in sodium-ion battery applications; Comparing Examples 1-5 with Example 8, it can be seen that when Examples 1-5 undergo mixed extrusion processing, the weight ratio of pre-oxidized coal to pitch is within the preferred range, and the carbon material products obtained in Examples 1-5 have I D / I G The value is within the preferred range, and it has higher capacity and first coulombic efficiency when used in sodium-ion battery applications; Comparing Examples 1-5 with Example 9, it can be seen that during the carbonization treatment in Examples 1-5, the high-temperature carbonization temperature is within the preferred range provided in this disclosure, and the carbon material product obtained in Examples 1-5 has a higher I... D / I G The value is within the preferred range, and it has higher capacity and initial coulombic efficiency when used in sodium-ion battery applications.

[0069] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0070] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0071] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. An amorphous carbon material, characterized in that, The Raman spectrum of the amorphous carbon material I D / I G The value is 0.93~1.2; the amorphous carbon material is 100×L c ×L a / d 002 The value is 1010~1200.

2. The amorphous carbon material according to claim 1, characterized in that, The Raman spectrum of the amorphous carbon material I D / I G The value is 0.93~0.

96.

3. A method for preparing amorphous carbon materials, characterized in that, Includes the following steps: S1. The raw coal is crushed, purified, and pre-oxidized to obtain pre-oxidized coal, wherein the volatile matter content in the raw coal is 20-45% by weight. S2. The pre-oxidized coal and pitch are mixed and extruded to obtain a coal / pitch mixture; S3. Carbonize the coal / asphalt mixture.

4. The method according to claim 3, characterized in that, In step S1, the volatile matter content in the raw coal is 25-40% by weight. Optionally, the D of the raw coal obtained from the crushing process 50 The particle size is 5~20μm.

5. The method according to claim 3, characterized in that, In step S1, the purification process includes: sequentially subjecting the raw coal to alkaline treatment and acid treatment; Optionally, the alkaline treatment conditions include: an alkaline concentration of 10-80% by weight, a treatment temperature of 100-200°C, and a treatment time of 1-8 hours; preferably, the alkaline concentration is 40-60% by weight, the treatment temperature is 120-150°C, and the treatment time is 2-4 hours; the alkaline solution is selected from one or more of sodium hydroxide solution and potassium hydroxide solution. Optionally, the acid treatment conditions include: an acid concentration of 5-30% by weight, a treatment temperature of 50-120°C, and a treatment time of 1-8 hours; preferably, an acid concentration of 5-15% by weight, a treatment temperature of 60-80°C, and a treatment time of 2-4 hours; the acid is selected from one or more of HCl solution and H2SO4 solution.

6. The method according to claim 3, characterized in that, In step S1, the pre-oxidation treatment conditions include: a treatment temperature of 50~500℃ and a treatment time of 1~8h in an oxygen-containing atmosphere; the oxygen concentration in the oxygen-containing atmosphere is 10~30% by volume%. Preferably, the pre-oxidation treatment conditions include: a treatment temperature of 150~300℃ and a treatment time of 3~6h in an oxygen-containing atmosphere; the oxygen concentration in the oxygen-containing atmosphere is 15~20% by volume. Optionally, in the pre-oxidation treatment, the heating rate is 0.5~10℃ / min, preferably 1~5℃ / min.

7. The method according to claim 3, characterized in that, In step S2, the weight ratio of the pre-oxidized coal to the pitch is 1~99:1, preferably 19~99:1; Preferably, the softening point of the asphalt is above 250°C; Optionally, the asphalt is selected from one or more of petroleum asphalt, coal tar pitch, oxidized asphalt, and mesophase asphalt.

8. The method according to claim 3, characterized in that, In step S2, the conditions for the mixed extrusion treatment include: an extrusion temperature of 100~400℃, preferably 200~300℃, and a residence time of 30~300min, preferably 60~180min.

9. The method according to claim 3, characterized in that, In step S3, the carbonization process includes: subjecting the coal / asphalt mixture to pre-carbonization and high-temperature carbonization in an inert atmosphere; wherein the temperature of the high-temperature carbonization process is higher than the temperature of the pre-carbonization process; and the inert atmosphere is selected from one or more of nitrogen and argon. Preferably, the pre-carbonization treatment conditions include: under an inert atmosphere, a pre-carbonization temperature of 500~900℃ and a pre-carbonization time of 1~8h; preferably, a pre-carbonization temperature of 500~600℃ and a pre-carbonization time of 2~5h; optionally, the heating rate of the pre-carbonization treatment is 0.5~10℃ / min, preferably 1~5℃ / min. Preferably, the conditions for the high-temperature carbonization treatment include: under an inert atmosphere, the high-temperature carbonization temperature is 1000~1800℃, and the high-temperature carbonization time is 1~8h; preferably, the high-temperature carbonization temperature is 1200~1600℃, and the high-temperature carbonization time is 2~5h; optionally, the heating rate of the high-temperature carbonization treatment is 0.5~10℃ / min, preferably 1~5℃ / min.

10. The amorphous carbon material prepared by the method according to any one of claims 3 to 9.

11. A negative electrode, characterized in that, Includes the amorphous carbon material as described in any one of claims 1-2 and 10.

12. A sodium-ion battery, characterized in that, Includes the negative electrode as described in claim 11.

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