Preparation method of hard carbon sodium ion battery negative electrode material
By preparing porous hard carbon sodium-ion battery anode materials, the problem of sodium ion deactivation during charging and discharging of hard carbon sodium-ion battery anode materials was solved, realizing the application of low-cost, high-performance battery materials.
Patent Information
- Application Number
- CN202511840447.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-08
- Publication Date
- 2026-01-16
AI Technical Summary
Existing hard carbon sodium-ion battery anode materials are prone to sodium ion deactivation during charge and discharge, resulting in reduced capacity and poor cycle stability.
Hard carbon sodium-ion battery anode materials were prepared through a simple process and surface modification etching. Green bamboo processing waste was used as raw material, and K2CO3 was combined for pre-sintering and high-temperature sintering to form a hard carbon material with a porous structure.
A low-cost preparation of hard carbon sodium-ion battery anode material has been achieved, which exhibits excellent discharge performance, good rate performance, and excellent cycle stability, with high discharge capacity retention and good structural stability.
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Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a preparation method of a hard carbon sodium ion battery negative electrode material and belongs to the technical field of sodium ion batteries. BACKGROUND
[0002] The hard carbon material is widely considered as one of the most promising negative electrode materials in sodium ion batteries due to its unique disordered microstructure, large carbon layer spacing and rich defects. First, the hard carbon material has a high reversible specific capacity and can provide a low sodium intercalation potential (<0.1 V vs. Na + / Na), which helps the sodium ion battery to obtain a high energy density. Second, the sodium ion radius is large, and the hard carbon material has an expanded layer spacing, which significantly reduces the energy barrier of sodium ion intercalation / deintercalation, which is the structural basis for efficient sodium storage. Third, the "non-graphitization" property of the hard carbon makes its structure very stable, and it is difficult to graphitize even at high temperatures, which endows the material with good cycle stability. Finally, the precursor of the hard carbon is widely sourced, including biomass (such as coconut shell, corn cob), coal-based materials (such as anthracite, coal pitch) and industrial by-products. These raw materials are abundant, which helps to reduce the cost of the battery.
[0003] However, the existing hard carbon sodium ion battery negative electrode material is prone to sodium ion deactivation during the charging and discharging process due to the intercalation and deintercalation of sodium ions, and has the problems of capacity reduction and poor cycle stability. SUMMARY
[0004] In view of the problems of the existing hard carbon sodium ion battery negative electrode material, such as high production cost of traditional resins and the like, and easy deactivation of sodium ions during the intercalation and deintercalation of sodium ions in the charging and discharging process, capacity reduction and poor cycle stability, the application provides a preparation method of a hard carbon sodium ion battery negative electrode material. The hard carbon sodium ion battery negative electrode material prepared by a simple process and surface modification etching has excellent charge and discharge performance, good rate performance and excellent cycle stability as a sodium ion battery negative electrode active material.
[0005] A preparation method of a hard carbon sodium ion battery negative electrode material, and the specific steps are as follows: (1) Bamboo processing waste powder is added to hydrochloric acid for room temperature soaking treatment, washed with deionized water, and dried to obtain pretreated bamboo waste powder; (2) The pretreated bamboo waste powder and K2CO3 are ground and uniformly mixed to obtain a mixed powder, and the mixed powder is pre-sintered under a protective atmosphere to obtain a precursor; (3) The precursor is high-temperature sintered under a protective atmosphere to obtain a hard carbon sodium ion battery negative electrode material.
[0006] Preferably, the concentration of the hydrochloric acid in step (1) is 3-6 mol / L, and the soaking treatment time is 12-24 h.
[0007] Preferably, the protective atmosphere is nitrogen or an inert gas.
[0008] Preferably, the mass ratio of the pretreated bamboo waste powder to K2CO3 in step (2) is 1:2.5~3.5.
[0009] Preferably, the pre-sintering temperature in step (2) is 500~650℃ and the time is 2~6h.
[0010] Preferably, the high-temperature sintering temperature in step (3) is 1200~1400℃ and the time is 2~4h.
[0011] Hard carbon sodium-ion battery anode material can be used as a negative electrode active material to prepare sodium-ion battery anodes: using hard carbon sodium-ion battery anode material as the negative electrode active material, the negative electrode active material, conductive agent (super P or acetylene black) and binder (PVDF, SA or CMC) are mixed evenly and then coated on the surface of the copper foil of the negative electrode current collector to form the active layer of the negative electrode material, thus obtaining the sodium-ion battery anode; the sodium-ion battery anode, sodium-ion battery cathode (metallic sodium), separator (glass fiber) and electrolyte (1 mol / L NaPF6 solution) are assembled into a hard carbon sodium-ion battery.
[0012] The beneficial effects of this invention are: (1) The hard carbon sodium-ion battery anode material of the present invention has the characteristics of simple process and low production cost. The cost of biomass-based precursor processing waste is much lower than the price of resin-based raw materials. (2) The hard carbon sodium-ion battery anode material of the present invention has excellent charge-discharge performance, cycle performance and rate performance; at 0.2A g -1 At the specified current density, its discharge capacity reaches 240.4 mAh g⁻¹. -1 After 200 cycles, the specific capacity retention rate is 81.76%, indicating high cycling stability. (3) The hard carbon sodium-ion battery anode material of the present invention has a stable structure during charging and discharging, is not prone to sodium deactivation, and the etched holes are conducive to sodium storage, thus increasing the material capacity. Attached Figure Description
[0013] Figure 1 The XRD pattern of the hard carbon sodium-ion battery anode material in Example 1 is shown. Figure 2 This is a SEM image of the hard carbon sodium-ion battery anode material from Example 1. Figure 3 The constant current voltage cycling performance curve of a sodium-ion battery at room temperature is shown for the preparation of the anode material of the hard carbon sodium-ion battery in Example 1. Figure 4Example 1: Constant current-voltage cycle performance curves of sodium-ion batteries at different rates at room temperature using hard carbon sodium-ion battery anode material. Figure 5 The constant current voltage cycling performance curve of the sodium-ion battery prepared with the hard carbon sodium-ion battery anode material in Example 2 at room temperature; Figure 6 Example 2: Constant current-voltage cycling performance curves of sodium-ion batteries at different rates at room temperature using hard carbon sodium-ion battery anode material. Figure 7 The constant current voltage cycling performance curve of the sodium-ion battery prepared with the hard carbon sodium-ion battery anode material in Example 3 at room temperature; Figure 8 Example 3 shows the constant current-voltage cycle performance curves of sodium-ion batteries at different rates at room temperature using the hard carbon sodium-ion battery anode material. Detailed Implementation
[0014] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.
[0015] Example 1: A method for preparing a hard carbon sodium-ion battery anode material, the specific steps of which are as follows: (1) Add the green bamboo processing waste powder to hydrochloric acid with a concentration of 3 mol / L and soak it at room temperature for 24 h. After washing with deionized water, dry it to obtain pretreated green bamboo waste powder. (2) Pretreated green bamboo waste powder and K2CO3 are ground and mixed to obtain a mixed powder. The mixed powder is placed in a protective atmosphere (argon) and a temperature of 600℃ for 4 hours to obtain a precursor. The mass ratio of the pretreated green bamboo waste powder to K2CO3 is 1:2.5. (3) The precursor was placed in a protective atmosphere (argon) and sintered at 1300℃ for 2 hours to obtain hard carbon sodium-ion battery anode material; The XRD pattern of the sodium-carbon battery anode material in this embodiment is shown below. Figure 1 ,from Figure 1 As can be seen, the X-ray diffraction (XRD) pattern shown in the figure indicates the presence of characteristic peaks of amorphous carbon in these composite materials, which are observed at approximately 2θ≈24° and ≈40°. This is attributed to the (002) and (100) crystal planes in the disordered carbon structure. The SEM image of the sodium-carbon battery anode material in this embodiment is shown below. Figure 2 ,from Figure 2 It can be seen that the material exhibits a sheet-like morphology with a length of 15~30μm; obviously, the surface of the material directly carbonized from bamboo powder shows an irregular open porous structure, which is conducive to the insertion and extraction of sodium ions. In this embodiment, the hard carbon sodium-ion battery anode material improves its internal sodium storage capacity by simple hole etching, thereby increasing the battery capacity. Hard carbon sodium-ion battery anode material can be used as a negative electrode active material to prepare sodium-ion battery anode: using hard carbon sodium-ion battery anode material as the negative electrode active material, the negative electrode active material, conductive agent and binder are mixed evenly and then coated on the surface of the negative electrode current collector copper foil to form a negative electrode material active layer, thus obtaining the sodium-ion battery anode. In this embodiment, metallic sodium is used as the positive electrode, glass fiber (Whatman, GF / A) is used as the separator, the electrolyte is a 1 mol / L NaPF6 solution, and copper foil is used as the negative electrode current collector. A 12 mm positive electrode material active layer (active components: hard carbon sodium ion battery negative electrode material (80 wt.%), conductive agent (SP) (10 wt.%), binder (PVDF) (10 wt.%)) is coated on the surface of the copper foil to form a negative electrode sheet, and a sodium ion battery is assembled. The constant current-voltage cycling performance curve of the sodium-ion battery prepared using the hard carbon sodium-ion battery anode material in this embodiment is shown in the figure below. Figure 3 The voltage window is between 0.01 and 2.5 V, with a current of 0.2 A g. -1 Cyclic testing was performed on the current density; from Figure 3 It can be seen that the discharge specific capacity is approximately 369.2 mA hg during the first cycle. -1 During the second cycle, the discharge specific capacity decreased slightly to approximately 243.2 mA hg. -1 After 200 cycles, the discharge specific capacity still remains at approximately 195.8 mAh g⁻¹. -1 The specific capacity retains 80.51% of the capacity. The constant current cycling performance curves of the sodium-ion battery at different rates at room temperature in this embodiment are shown in the figure. Figure 4 ,from Figure 4 It can be seen that after five consecutive cycles of testing at capacities of 0.2C, 0.5C, 1C, 2C, and 5C respectively, the corresponding specific capacity is 256.9 mA hg. -1 237.9 mA hg -1 193.7 mA hg -1 110.7 mA hg -1 53.8 mA hg -1 When charged and discharged from 5C to 0.2C again, the specific capacity was slightly higher than before, reaching 294.8 mA hg. -1 This indicates that the sodium-ion battery anode material has high rate capability and stable cycle performance. Therefore, the hard carbon sodium-ion battery anode material used in this embodiment not only exhibits stable discharge and high rate capability, but also excellent cycle stability at 0.2 A g. -1 After 200 cycles at the specified current density, the specific capacity retention rate reached 80.51%, indicating that the sodium-ion battery has good cycle stability and capacity retention performance.
[0016] Example 2: A method for preparing a hard carbon sodium-ion battery anode material, the specific steps of which are as follows: (1) Add the green bamboo processing waste powder to hydrochloric acid with a concentration of 4 mol / L and soak it at room temperature for 18 h. After washing with deionized water, dry it to obtain pretreated green bamboo waste powder. (2) Pretreated green bamboo waste powder and K2CO3 are ground and mixed to obtain a mixed powder. The mixed powder is placed in a protective atmosphere (nitrogen) and a temperature of 550℃ for 6 hours to obtain a precursor. The mass ratio of the pretreated green bamboo waste powder to K2CO3 is 1:3. (3) The precursor was placed in a protective atmosphere (nitrogen) and sintered at 1200℃ for 2.5h to obtain hard carbon sodium-ion battery anode material; The sodium-ion battery assembly and performance testing methods in this embodiment are the same as those in Embodiment 1; The constant current-voltage cycling performance curve of the sodium-ion battery prepared using the hard carbon sodium-ion battery anode material in this embodiment is shown in the figure below. Figure 5 The voltage window is between 0.01 and 2.5 V, with a current of 0.2 A g. -1 Cyclic testing was conducted at the specified current density; during the first cycle, the discharge specific capacity was approximately 370.8 mA hg. -1 During the second cycle, the discharge specific capacity decreased slightly to approximately 243.7 mA hg. -1 After 200 cycles, the discharge specific capacity still remains at approximately 193.8 mA hg. -1 The specific capacity retention rate reached 79.52%. The constant current cycling performance curves of the sodium-ion battery at different rates at room temperature in this embodiment are shown in the figure. Figure 6 ,from Figure 6 It can be seen that after five consecutive cycles of testing at capacities of 0.2C, 0.5C, 1C, 2C, and 5C, the corresponding specific capacity is 370.4 mA hg. -1 228.9 mA hg -1 182.8 mA hg -1 101.7 mA hg -1 48.8mA hg -1When charged and discharged again from 5C to 0.2C, the specific capacity reached 247.8 mA hg, slightly higher than before. -1 This indicates that the sodium-ion battery anode material has high rate capability and stable cycle performance.
[0017] Example 3: A method for preparing a hard carbon sodium-ion battery anode material, the specific steps of which are as follows: (1) Add the green bamboo processing waste powder to hydrochloric acid with a concentration of 6 mol / L and soak it at room temperature for 12 h. After washing with deionized water, dry it to obtain pretreated green bamboo waste powder. (2) Pretreated green bamboo waste powder and K2CO3 are ground and mixed to obtain a mixed powder. The mixed powder is placed in a protective atmosphere (nitrogen) and a temperature of 650°C for 2.5 hours to obtain a precursor. The mass ratio of the pretreated green bamboo waste powder to K2CO3 is 1:3.5. (3) The precursor was placed in a protective atmosphere (nitrogen) and sintered at 1400℃ for 3 hours to obtain hard carbon sodium-ion battery anode material. The sodium-ion battery assembly and performance testing methods in this embodiment are the same as those in Embodiment 1; The constant current-voltage cycling performance curve of the sodium-ion battery prepared using the hard carbon sodium-ion battery anode material in this embodiment is shown in the figure below. Figure 7 The voltage window is between 0.01 and 2.5 V, with a current of 0.2 A g. -1 Cyclic testing was conducted at the specified current density; during the first cycle, the discharge specific capacity was approximately 368.8 mA hg. -1 During the second cycle, the discharge specific capacity decreased slightly to approximately 244.2 mA hg. -1 After 200 cycles, the discharge specific capacity still remains at approximately 197.7 mA hg. -1 The specific capacity retains 80.96% of the capacity. The constant current cycling performance curves of the sodium-ion battery at different rates at room temperature in this embodiment are shown in the figure. Figure 8 ,from Figure 8 It can be seen that after five consecutive cycles of testing at capacities of 0.2C, 0.5C, 1C, 2C, and 5C respectively, the corresponding specific capacity is 360.4 mA hg. -1 233.9 mA hg -1 188.8 mA hg -1 105.7mA hg -1 50.8 mA hg -1 When charged and discharged from 5C to 0.2C again, the specific capacity was slightly higher than before, reaching 241.8 mA hg. -1 This indicates that the sodium-ion battery anode material has high rate capability and stable cycle performance.
[0018] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A method for preparing a hard carbon sodium-ion battery anode material, characterized in that, The specific steps are as follows: (1) The green bamboo processing waste powder is added into hydrochloric acid for room temperature soaking treatment, washed with deionized water, and dried to obtain pretreated green bamboo waste powder; (2) The pretreated green bamboo waste powder and K2CO3 are ground and uniformly mixed to obtain a mixed powder, and the mixed powder is pre-sintered under a protective atmosphere to obtain a precursor; (3) The precursor is high-temperature sintered under a protective atmosphere to obtain a hard carbon sodium ion battery negative electrode material.
2. The method for preparing the hard carbon sodium-ion battery anode material according to claim 1, characterized in that: The concentration of hydrochloric acid in step (1) is 3-6 mol / L, and the soaking treatment time is 12-24 h.
3. The method for preparing the hard carbon sodium-ion battery anode material according to claim 1, characterized in that: The protective atmosphere is nitrogen or inert gas.
4. The method for preparing the hard carbon sodium-ion battery anode material according to claim 1, characterized in that: The mass ratio of pretreated green bamboo waste powder to K2CO3 in step (2) is 1:2.5-3.
5.
5. The method for preparing the hard carbon sodium-ion battery anode material according to claim 1, characterized in that: The pre-sintering temperature in step (2) is 500-650 DEG C, and the time is 2-6 h.
6. The method for preparing the hard carbon sodium-ion battery anode material according to claim 1, characterized in that: The high-temperature sintering temperature in step (3) is 1200-1400 DEG C, and the time is 2-4 h.