A method for preparing coal tar pitch-based hard carbon anode material
By crosslinking and modifying coal tar pitch, hard carbon materials were prepared, which solved the problems of low initial coulombic efficiency and insufficient sodium storage capacity of existing carbon materials in sodium-ion batteries, and improved the structural stability and capacity retention of the materials.
Patent Information
- Application Number
- CN202610172000.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-06
- Publication Date
- 2026-05-26
AI Technical Summary
Existing carbon materials used as anode materials for sodium-ion batteries suffer from problems such as low initial coulombic efficiency, insufficient sodium storage capacity, and structural instability. In particular, the preparation processes of graphite derivatives and soft carbon materials are difficult to improve through simple optimization.
Coal tar pitch was pretreated with crosslinking agents and modifiers, and a hard carbon precursor was obtained through heat treatment. Finally, hard carbon materials were prepared by carbonization at high temperature.
The first coulombic efficiency and sodium storage capacity of hard carbon materials were improved, the structural stability of the materials was enhanced, and a high capacity retention rate was achieved.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a battery anode material, and more particularly to a method for preparing a hard carbon anode material for batteries, belonging to the field of anode materials. Background Technology
[0002] Carbon materials not only possess advantages such as abundant resources and low cost, but also exhibit high sodium storage capacity, good rate capability, and excellent cycle stability, making them one of the most promising anode materials currently available. However, the preparation of graphite derivatives in carbon materials requires complex pre-oxidation treatment, resulting in low initial coulombic efficiency and problems such as active material agglomeration and structural collapse during long-term charge-discharge cycles. Soft carbon precursors are inherently limited by low sodium storage capacity and an insignificant charge-discharge voltage plateau, defects that are difficult to overcome through simple process optimization. In contrast, hard carbon materials possess the fundamental characteristics of wide-ranging raw material sources, relatively flexible preparation processes, and significant cost advantages for industrialization. Furthermore, they have suitable interlayer spacing and abundant pore structures adapted to sodium ion storage, effectively optimizing ion transport kinetics. They also combine balanced sodium storage capacity, high initial coulombic efficiency, and a stable charge-discharge voltage plateau, and achieve capacity retention during long-term cycling thanks to excellent structural stability, making them the most promising anode materials for sodium-ion batteries. Summary of the Invention
[0003] This invention provides a method for preparing hard carbon. The method first pretreats coal tar pitch with a crosslinking agent and a modifier, then obtains a hard carbon precursor through heat treatment, and finally obtains a hard carbon anode material through high-temperature carbonization.
[0004] The technical solution adopted in this invention includes the following steps:
[0005] (1) Weigh a certain amount of coal tar pitch and pre-oxidize it in a muffle furnace. After crushing, the pre-oxidized coal tar pitch is obtained.
[0006] (2) The pre-oxidized coal tar pitch in step (1) is acid-washed for a period of time, then filtered with water until neutral, and dried.
[0007] (3) The acid-treated pre-oxidized coal tar pitch, crosslinking agent and modifier in step (2) are mixed evenly and then treated at low temperature in a tube furnace under nitrogen atmosphere to obtain the precursor;
[0008] (4) The precursor in step (3) is carbonized at high temperature in an argon atmosphere to obtain hard carbon material.
[0009] Further preferred, the pre-oxidation in step (1) is pre-oxidation in air at 200°C for 2 hours.
[0010] Further optimization, in step (2) 2 mol L -1Pickle with hydrochloric acid for 2 days.
[0011] Further optimization is that the crosslinking agent in step (3) is bone gluten powder and the modifier is polyvinylidene fluoride.
[0012] Further preferred, in step (3), the mass ratio of acid-treated pre-oxidized coal tar pitch, crosslinking agent and modifier is (2-5):(2-5):1, preferably the mass ratio of pre-oxidized coal tar pitch and crosslinking agent is 5:5:1.
[0013] Further optimization involves using a low-temperature treatment at 450°C for 6 hours in step (3).
[0014] Further optimization is made by calcining at 1300℃ in step (4) and holding for 2 hours.
[0015] The coal tar pitch-based hard carbon obtained by this invention can be used as an active material for battery anode materials, such as active materials for sodium battery anode materials.
[0016] Compared with conventional methods for preparing coal tar hard carbon, this invention has the following advantages:
[0017] This invention crosslinks coal tar pitch with a crosslinking agent, resulting in a higher product yield than conventional preparation methods.
[0018] This invention improves the interlayer spacing of materials by using a modifier, resulting in hard carbon with high specific capacity and first coulombic efficiency. Attached Figure Description
[0019] Figure 1 The constant current charge-discharge capacity-voltage curve of the coal tar pitch hard carbon material of this invention.
[0020] Figure 2 The coal tar pitch hard carbon material of this invention is in 0.5 A g -1 Circulation curve
[0021] Figure 3 The coal tar pitch hard carbon material of this invention is at 0.1 mV s -1 CV curve at low scan rate
[0022] Figure 4 SEM image of the coal tar pitch hard carbon material HC-2(1300) of this invention. Detailed Implementation
[0023] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.
[0024] Example 1
[0025] 1) Weigh 10 g of coal tar pitch as raw material.
[0026] 2) Pre-oxidize at 200 °C in a muffle furnace for 2 h, and after pulverization, pre-oxidized coal tar pitch is obtained.
[0027] 3) Pickle the pre-oxidized coal tar pitch in step 2) with 2 mol / L -1 hydrochloric acid for 2 days, then filter with clear water until neutral, and dry.
[0028] 4) Mix the pre-oxidized coal tar pitch, prion bone powder, and polyvinylidene fluoride in step 3) evenly at a ratio of 5:5:1.
[0029] 5) Treat the mixture in step 4) at 450 °C for 6 h under a nitrogen atmosphere in a tube furnace to obtain a precursor.
[0030] 6) Carbonize the precursor in step 5) at 1300 °C for 2 h under an argon atmosphere in a tube furnace to obtain a hard carbon material, denoted as HC-2(1300).
[0031] 7) Use the carbon material prepared in step 6) as the active material of the battery negative electrode material for the preparation of a sodium-ion battery. Weigh 80 mg of the prepared carbon material powder, 10 mg of conductive carbon black, and 10 mg of sodium alginate according to a mass ratio of 8:1:1 into an agate mortar and stir evenly. Drop an appropriate amount of deionized water and stir until it becomes a uniform slurry. Then evenly coat the slurry on the surface of a copper (Cu) foil, dry it at 80 °C for 12 h under vacuum conditions, cut the copper foil with the active material into circular negative electrode sheets, and immediately transfer them to a glove box for standby.
[0032] 8) Assemble the simulated battery inside a glove box filled with an Ar atmosphere. Use the prepared carbon material electrode sheet as the negative electrode, 1.0 M NaPF6 in DIGYME = 100 vol% of commercial electrolyte as the electrolyte, and a Na metal sheet as the counter electrode to assemble a 2032 coin-type battery.
[0033] 9) Place the assembled coin-type battery in a Blue-Electrochemical Test System after leaving it standing for 8 h. Perform charge-discharge tests on it within a voltage range of 0.01 - 2.5 V (vs. Na + / Na, the same below). The electrochemical test results show that the prepared hard carbon material has a specific capacity of 338.94 mA h g -1 , and the first charge-discharge efficiency is 83.26%. Figure 2 The hard carbon material HC-2(1300) is first activated at 0.05 A g -1 for 5 cycles, and then continuously cycled at 0.5 A g -1 for 100 cycles. After that, the material capacity is 231.7 mA h g -1 , and the capacity retention rate is 91.26%.
[0034] Example 2
[0035] 1) Weigh 10 g of coal tar pitch as raw material.
[0036] 2) Pre-oxidize at 200 °C in a muffle furnace for 2 h, pulverize to obtain pre-oxidized coal tar pitch.
[0037] 3) Pickle the pre-oxidized coal tar pitch in step 2) with 2 mol / L -1 hydrochloric acid for 2 days, then filter with clear water until neutral, and dry.
[0038] 4) Mix the pre-oxidized coal tar pitch in step 3): bone powder: polyvinylidene fluoride in a ratio of 2:2:1 evenly.
[0039] 5) Treat the mixture in step 4) at 450 °C in a nitrogen atmosphere in a tube furnace for 6 h to obtain a precursor.
[0040] 6) Carbonize the precursor in step 5) at 1300 °C in an argon atmosphere in a tube furnace for 2 h to obtain hard carbon material, denoted as HC-5(1300).
[0041] 7) Use the carbon material prepared in step 6) as the active substance of the battery negative electrode material for the preparation of sodium-ion batteries. Weigh 80 mg of the prepared carbon material powder, 10 mg of conductive carbon black, and 10 mg of sodium alginate according to a mass ratio of 8:1:1 into an agate mortar and stir evenly. Drop in an appropriate amount of deionized water and stir until it becomes a uniform paste. Then evenly coat the paste on the surface of a copper (Cu) foil, dry at 80 °C for 12 h under vacuum conditions, cut the copper foil with the active material into round negative electrode sheets, and immediately transfer them to a glove box for standby.
[0042] 8) Assemble the simulated battery in a glove box filled with an Ar atmosphere. Use the prepared carbon material electrode sheet as the negative electrode, 1.0 M NaPF6 in DIGYME = 100 vol% of commercial electrolyte as the electrolyte, and a Na metal sheet as the counter electrode to assemble a 2032 coin-type battery.
[0043] 9) Place the assembled coin-type battery in a BlueTEC test system after leaving it standing for 8 h. In the voltage range of 0.01 - 2.5 V (vs. Na + / Na, the same below), conduct charge-discharge tests on it. The electrochemical test results show that the prepared hard carbon material has a specific capacity of 298.51 mA h g -1 , and the first charge-discharge efficiency is 83.64%. From Figure 2 The hard carbon material HC-5(1300) is first activated at 0.05 A g -1 for 5 cycles, and then continuously cycled at 0.5 A g -1 for 100 cycles. After that, the material capacity is 182.6 mA h g -1The capacity retention rate was 97.33%.
Claims
1. A method for preparing a coal tar pitch-based hard carbon anode material, characterized in that, Includes the following steps: (1) Weigh a certain amount of coal tar pitch and pre-oxidize it in a muffle furnace. After crushing, the pre-oxidized coal tar pitch is obtained. (2) The pre-oxidized coal tar pitch in step (1) is acid-washed for a period of time, then filtered with water until neutral, and dried. (3) The acid-treated pre-oxidized coal tar pitch, crosslinking agent and modifier in step (2) are mixed evenly and then treated at low temperature in a tube furnace under nitrogen atmosphere to obtain the precursor; (4) The precursor in step (3) is carbonized at high temperature in an argon atmosphere to obtain hard carbon material.
2. The method according to claim 1, characterized in that, The pre-oxidation in step (1) is to pre-oxidize in air at 200°C and keep it at that temperature for 2 hours.
3. The method according to claim 1, characterized in that, In step (2), 2 mol L -1 Pickle with hydrochloric acid for 2 days.
4. The method according to claim 1, characterized in that, The crosslinking agent in step (3) is bone gluten powder, and the modifier is polyvinylidene fluoride.
5. The method according to claim 1, characterized in that, In step (3), the mass ratio of acid-treated pre-oxidized coal tar pitch, crosslinking agent and modifier is (2-5):(2-5):1, preferably the mass ratio of pre-oxidized coal tar pitch and crosslinking agent is 5:5:
1.
6. The method according to claim 1, characterized in that, In step (3), the low-temperature treatment is performed at 450℃ for 6 hours.
7. The method according to claim 1, characterized in that, In step (4), the high-temperature roasting is 1300℃ and held for 2 hours.
8. The coal tar pitch-based hard carbon anode material prepared according to any one of claims 1-7.
9. The application of the coal tar pitch-based hard carbon anode material prepared according to any one of claims 1-7, used as an active material for battery anode materials, such as an active material for sodium battery anode materials.