High-performance interface-regulated hard carbon negative electrode material, and preparation method and application thereof
Patent Information
- Application Number
- CN202610342038.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-19
- Publication Date
- 2026-08-21
AI Technical Summary
然而，硬碳的倍率性能和循环稳定性仍受到挑战，尤其是在商业化潜力较大的酯基电解液中，这主要是硬碳表面的SEI膜结构的影响
1、本发明提供了一种操作简易、原料廉价且易于规模化生产的高性能界面调控硬碳材料的制备方法，具有较高的商业价值，易于规模化生产。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of sodium-ion battery electrode material technology, specifically relating to a high-performance interface-controlled hard carbon anode material, its preparation method, and its application. Background Technology
[0002] Fossil fuels have brought tremendous development to civilized society; however, their excessive use has also led to severe energy crises and environmental pollution. With the global overconsumption of fossil fuels and the increasing severity of environmental problems, the demand for sustainable and renewable energy sources such as solar and wind power is urgent, leading to the widespread application of safe, low-cost, and high-capacity energy storage systems. Against the backdrop of the widespread use of lithium-ion batteries in mobile phones, computers, and electric vehicles, the drawbacks of lithium are gradually becoming apparent. Limited global lithium reserves leading to supply shortages, uneven distribution, and high costs severely restrict the development of energy storage devices. In response to this situation, vigorously developing sodium-ion batteries has broad market prospects and significant national strategic development importance.
[0003] Firstly, sodium and lithium are elements in the same group, and sodium has similar electrochemical properties to lithium. Moreover, sodium is abundant and inexpensive. Therefore, sodium-ion batteries (SIBs) are the next generation of commercially viable secondary batteries after lithium-ion batteries (LIBs). These advantages make sodium-ion batteries highly promising for applications in large-scale energy storage and other fields.
[0004] Currently, hard carbon (HC) has become the dominant anode material for SIBs due to its superior electrochemical performance and lower cost. Furthermore, HC can be produced from various readily available waste and renewable biomass sources, making it an ideal material for the circular economy. Compared to other traditional carbon anode materials such as artificial graphite, natural graphite, mesophase carbon microspheres, and soft carbon, HC is currently the most promising commercial anode material for SIBs. HC possesses a complex microstructure and multiple sodium storage sites, enhancing its sodium storage capacity. However, the rate performance and cycle stability of HC remain challenging, especially in ester-based electrolytes with significant commercial potential, primarily due to the influence of the SEI film structure on the HC surface. Considering the difficulty in introducing non-metallic dopants and some low-melting-point metals during the high-temperature preparation process of HC, while the presence of high-melting-point metals may induce graphitization of the carbon structure, further challenges exist.
[0005] Therefore, it is urgent to develop new hard carbon anode materials that have long lifespan, high rate capability, high safety, and are suitable for sodium-ion batteries. Summary of the Invention
[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a high-performance interface-controlled hard carbon anode material and its preparation method. The hard carbon anode material prepared by this invention introduces heteroatoms into the carbon material to accelerate reaction kinetics and sodium ion diffusion kinetics in the hard carbon, thereby improving the rate performance and power density of sodium-ion batteries. Furthermore, this invention also provides applications of the aforementioned high-performance interface-controlled hard carbon material in the preparation of composite electrode slurries, sodium-ion batteries, or sodium-ion secondary batteries.
[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for preparing high-performance interface-controlled hard carbon materials includes the following steps: 1) Mix bismuth- or nitrogen-containing precursors and hard carbon materials in a certain proportion, and then directly dry-mill or wet-mill and dry to obtain mixture I; 2) Mixture I was heated to a certain temperature under an inert atmosphere and a certain pressure to undergo high-temperature doping heat treatment, and then cooled to room temperature to obtain a high-performance interface-controlled hard carbon material.
[0008] Further, in step 1), the hard carbon material is biomass-based hard carbon, polymer-based hard carbon, or fossil fuel-based hard carbon material, wherein the median particle size D50 of the hard carbon particles is 0.05-20 μm; the carbon content in the hard carbon particles is 50%-99.9%, preferably 90%-99.9%; the bismuth- or nitrogen-containing precursor is one or a mixture of two or more of bismuth subnitrate, bismuth oxide, bismuth citrate, bismuth ammonium citrate, bismuth carbonate, bismuth nitrate pentahydrate, bismuth trichloride, bismuth sulfate, bismuth titanate, bismuth phosphate, ammonium citrate, glycine, ammonium fluoride, ammonium nitrate, and ammonium sulfide.
[0009] Furthermore, in step 1), the mixing mass ratio of hard carbon material and precursor is 200:1 to 1:20; during wet milling, the solution used is one or more of water, acetonitrile, methanol, propanol, acetone, ethanol, NMP, DMSO, and DMS, and the mass ratio of the mixed dry material of nitrogen-containing precursor and hard carbon material to the solution in the wet mixing is 200:1 to 1:200; the drying operation after wet mixing is: keeping at 50℃ to 150℃ for 0.5 to 24 hours.
[0010] Furthermore, in step 1), the equipment used for mixing is a high-speed ball mill, a horizontal ball mill, a stirred ball mill, a VC-type mixing equipment, or a V-type mixing equipment, with a mixing time of 0.02 to 12 hours and a rotation speed of 50 to 2000 rpm.
[0011] Furthermore, in step 2), the inert atmosphere is formed by one or more of nitrogen, argon, and helium; the gas flow rate under the inert atmosphere is 0.2 to 10 L / min, and the ventilation time is 0.1 to 20 h.
[0012] Furthermore, in step 2), the pressure of the high-temperature doping heat treatment is 0.9 to 1.2 atmospheres; the high-temperature doping heat treatment is selected from either of the following two methods: Method 1: holding at 200℃ to 1000℃ for 0.01 to 5 hours, with a heating rate of 1 to 10℃ / min; Method 2: first holding at 200℃ to 600℃ for 0.01 to 3 hours, then heating to 600℃ to 1000℃ and holding for 0.01 to 5 hours, with a heating rate of 1 to 10℃ / min.
[0013] Furthermore, the present invention also provides a high-performance interface-controlled hard carbon anode material prepared by the above method. Doping elements in the precursor can be detected on the surface of the hard carbon product, wherein the Bi element can also diffuse into the bulk phase and form a synergistic effect with the elements on the surface.
[0014] Based on a general inventive concept, this invention provides the application of the aforementioned high-performance interface-controlled hard carbon material in the preparation of composite electrode slurries, sodium-ion batteries, or sodium-ion secondary batteries.
[0015] This invention also provides a method for preparing composite electrode paste using the high-performance interface-controlled hard carbon material, comprising the following steps: a) Weigh a certain amount of active material and conductive agent, and place them in a container in sequence to obtain a mixed powder; the active material is a high-performance interface-controlled hard carbon material prepared by the above method. b) Preparation of the mixed slurry: A certain amount of binder dispersion and a certain amount of solvent are added to the mixed powder in step a). The mixture is ultrasonically dispersed at a power of 50-120 W for 5-15 min and stirred at a speed of 200-800 r / min for 3-24 h to ensure that the active material and conductive agent are evenly dispersed, thus obtaining the composite electrode slurry.
[0016] c) The obtained composite electrode slurry is uniformly coated onto the surface of copper foil, and then dried in a vacuum oven at a temperature of 50–120°C for 5–24 hours. The resulting electrode sheet can be used for battery assembly after cutting. Furthermore, the conductive agent in step a) is carbon black (Super-P) or acetylene black; Furthermore, the solute in the binder dispersion in step a) is one or more of carboxymethyl cellulose, sodium alginate, ammonium alginate, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid (PAA), lithium-ionized polyacrylic acid (lithium-ionized PPA), styrene-butadiene rubber, and polystyrene-butadiene copolymer, and the solvent is water or a mixture of water and ethanol.
[0017] Furthermore, the solvent in step b) is one of deionized water, ethanol, and NMP.
[0018] Furthermore, in step b), the mass of the solvent is 1 to 5 times the mass of the mixed powder.
[0019] Furthermore, in the composite electrode slurry obtained in step b), the weight ratio of the solute components in the dispersion of active material, conductive agent, and binder is (70-98):(1-20):(1-20).
[0020] This invention also provides a method for preparing sodium-ion batteries or sodium-ion secondary batteries using the aforementioned high-performance interface-controlled hard carbon anode material, comprising the following steps: S1. Preparation of electrode sheet: A composite electrode slurry is prepared by high-performance interface-controlled hard carbon anode material, coated on the current collector, dried at 50~150℃ for 4~24h, and then made into a button electrode sheet with a diameter of 10-16 mm using a punch. S2. Button cell assembly: Select sodium metal sheets or sodium vanadium phosphate positive electrode sheets and assemble them into button cells.
[0021] Furthermore, the current collector in step S1 is a copper foil or an aluminum foil.
[0022] Specifically, the separator assembled in step S2 is a Whatman GF / D or Celgard polypropylene separator, and the main component of the electrolyte used in the battery is sodium salt (sodium hexafluorophosphate); preferably, the electrolyte is 1 M NaPF6 / EC+DEC or 1 M NaPF6 / DME.
[0023] Compared with the prior art, the advantages of the present invention are: 1. This invention provides a method for preparing high-performance interface-controlled hard carbon materials that is easy to operate, uses inexpensive raw materials, and is easy to scale up, and has high commercial value and is easy to scale up.
[0024] 2. This invention overcomes the shortcomings of existing hard carbon anode materials, such as low cycle life, poor rate performance, low rapid sodium insertion / extraction capability, and poor charging performance. The hard carbon anode material prepared in this invention introduces heteroatoms into the surface and bulk phase of hard carbon, accelerating reaction kinetics by improving the interface SEI structure and the diffusion kinetics and pore-filling behavior of sodium ions in hard carbon. This effectively improves the rate capacity and cycle stability of sodium storage, demonstrating its broad application prospects in the field of sodium-ion battery anode materials. Attached Figure Description
[0025] Figure 1 These are SEM images of Examples 1 and 4 of this invention; Figure 2 Cyclic performance diagram of sodium-ion batteries made from hard carbon anode materials of Examples 1, 2, 3, 4 and Comparative Examples 1, 2 in ester-based electrolyte; Figure 3 Rate performance of sodium-ion batteries made from hard carbon anode materials in Examples 1, 2, 3, 4 and Comparative Examples 1, 2 in ester-based electrolytes. Figure 4 The graph shows the cycling performance of sodium-ion batteries made using the hard carbon anode materials of Examples 1, 3 and Comparative Example 1 in an ether-based electrolyte. Detailed Implementation
[0026] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0027] Unless otherwise specified, the experimental methods in the following examples are generally performed under conventional conditions. Unless otherwise specified, the raw materials and reagents used are all commercially available products.
[0028] Hard carbon T2, battery grade, item number S20241902007, from Duoduo Chemical Reagents.
[0029] Bismuth subnitrate (BiONO3), purity 99.5%, CAS No. 10361-46-3, Aladdin reagent; Glycine (NH2CH2COOH), purity 99%, CAS No. 56-40-6, Aladdin reagent; Bismuth ammonium citrate (C6H) 11 BiNO7), purity 99%, CAS number 31886-41-6, Aladdin reagent; Bismuth citrate (C6H5BiO7), purity 99%, CAS No. 813-93-4, Aladdin reagent; Ammonium citrate (C6H) 17 N3O7), purity 99%, CAS number 3458-72-8, Inokai reagent. Example 1
[0030] This embodiment provides a high-performance interface-controlled hard carbon anode material and its preparation method, the specific steps of which are as follows: 1) T2 hard carbon and bismuth citrate were mixed at a mass ratio of 100:3 and then dry-milled. The mixture was ground and mixed using an MSK-PCV-300 planetary centrifugal mixer from Kejing Company to obtain mixture I. 2) Mixture I was heat-treated by heating it to 600 degrees Celsius at 5°C / min under an argon atmosphere and normal pressure, and then holding it at that temperature for 2 hours. It was then allowed to cool naturally to room temperature (20-30°C, 25°C in this example) to obtain bismuth-nitrogen synergistic modified hard carbon material I.
[0031] The morphology and particle size of the product from Example 1 were observed using scanning electron microscopy. The obtained SEM and EDS elemental distribution images are shown below. Figure 1 As shown, the doped sample contains micron-sized hard carbon particles and a small amount of debris, with an intact surface and uniform elemental distribution. Example 2
[0032] This embodiment provides a high-performance interface-controlled hard carbon anode material and its preparation method. The difference from Embodiment 1 is that the doped precursor used in step 1 is glycine, and the rest is the same as in Embodiment 1. Example 3
[0033] This embodiment provides a high-performance interface-controlled hard carbon anode material and its preparation method. The difference from Embodiment 1 is that the doped precursor used in step 1 is bismuth nitrate, and the rest is the same as in Embodiment 1. Example 4
[0034] This embodiment provides a high-performance interface-controlled hard carbon anode material and its preparation method. The difference from Embodiment 1 is that the precursor used in step 1 is bismuth ammonium citrate, the doping method is wet mixing, the solution is pure water, the mass ratio of Bi / N precursor and hard carbon dry material to pure water is 1:1, and after grinding, it is dried at 60°C for 12 hours. The rest is the same as in Embodiment 1. Example 5
[0035] This embodiment provides a high-performance interface-controlled hard carbon anode material and its preparation method. The difference from Embodiment 1 is that the doped precursor used in step 1 is bismuth powder, and the rest is the same as in Embodiment 1. Example 6
[0036] This embodiment provides a high-performance interface-controlled hard carbon anode material and its preparation method. The difference from Embodiment 1 is that the doped precursor used in step 1 is bismuth oxide, and the rest is the same as in Embodiment 1. Example 7
[0037] This embodiment provides a high-performance interface-controlled hard carbon anode material and its preparation method. The difference from Embodiment 1 is that the doped precursor used in step 1 is bismuth trichloride, and the rest is the same as in Embodiment 1. Example 8
[0038] This embodiment provides a high-performance interface-controlled hard carbon anode material and its preparation method. The difference from Embodiment 1 is that the doped precursor used in step 1 is a mixture of glycine and bismuth powder in a molar ratio of 1:1, and the rest is the same as in Embodiment 1.
[0039] In other embodiments, the following conditions are met: In step 1), the mixing mass ratio of hard carbon material and precursor is 200:1 to 1:20; during wet milling, the solution used is one or more of water, acetonitrile, methanol, propanol, acetone, ethanol, NMP, DMSO, and DMS, and the mass ratio of the dry mixture of nitrogen-containing precursor and hard carbon material to the solution in the wet mixing is 200:1 to 1:200; the drying operation after wet mixing is: holding at 50℃ to 150℃ for 0.5 to 24 hours; in step 1), the equipment used for mixing is a high-speed ball mill, a horizontal ball mill, a stirred ball mill, a VC-type mixing equipment, or a V-type mixing equipment, the mixing time is 0.02 to 12 hours, and the rotation speed is 50 to 2000 rpm. In step 2), the inert atmosphere is formed by one or more of nitrogen, argon, and helium; the gas flow rate under the inert atmosphere is 0.2–10 L / min, and the ventilation time is 0.1–20 h; and the following conditions are met: in step 2), the pressure of the high-temperature doping heat treatment is 0.9–1.2 atmospheres; the high-temperature doping heat treatment is selected from either of the following two methods: Method 1: holding at 200℃–1000℃ for 0.01–5 h, with a heating rate of 1–10℃ / min; Method 2: first holding at 200℃–600℃ for 0.01 h–3 h, then heating to 600℃–1000℃ and holding for 0.01 h–5 h, with a heating rate of 1–10℃ / min. Both methods can achieve the effects of the present invention.
[0040] Comparative Example 1 This comparative example uses raw, untreated T2 hard carbon directly as the negative electrode material.
[0041] Comparative Example 2 The difference between this comparative example and Example 1 is that no precursor is added in step 1, while the rest is the same as in Example 1.
[0042] Performance testing The products prepared in Examples 1-8 and Comparative Examples 1-2 were used to assemble batteries and their electrochemical performance was tested. The specific testing methods are as follows: Using the CR2032 coin cell model, with a sodium metal sheet as the counter electrode, a Whatman GF / D separator, and 1M NaPF6 in DEC:EC=1:1 Vol% (Suzhou Duoduo Chemical Technology Co., Ltd., catalog number NP-001) and 1M NaPF6 in DME=100 Vol% (Suzhou Duoduo Chemical Technology Co., Ltd., catalog number NP-035) as the electrolyte, the prepared negative electrode disc, sodium metal sheet (as counter electrode), separator, and electrolyte were assembled into a coin cell.
[0043] Cyclic performance testing was conducted under the following conditions: constant current charge-discharge cycle testing was performed at a current density of 0.1 A / g, or the electrodes were activated by cycling 3 times at a current density of 0.1 A / g, followed by constant current charge-discharge cycle testing at high current densities of 0.5 A / g and 0.8 A / g, with a charge-discharge voltage range of 0.01–2 V.
[0044] Following the assembly and testing methods described above, the cycle performance of the high-performance interface-controlled hard carbon anode materials prepared in Examples 1-8 of this invention and Comparative Examples 1-2 was tested according to the same assembly and testing methods. The results are shown in Table 1 and... Figure 2 , 3 As shown in Figure 4.
[0045] Table 1 Performance test results of Examples 1-8 and Comparative Examples 1-2 in ester-based electrolytes From Table 1 and Figure 2 , 3 As can be seen from Figures 1 and 4, the doped hard carbon anode materials obtained in Examples 1-8 exhibit superior cycling performance, while Comparative Examples 1-2 show a significant performance decline. Specifically, Example 3 retains 79.42% (244.6 mAh / g) of capacity after 300 cycles at 0.1 A / g, and 86.6% (183.6 mAh / g) after 400 cycles at 0.5 A / g; Example 4 retains 89.0% (275.7 mAh / g) of capacity after 300 cycles at 0.1 A / g. Figure 4The cycling graphs of the ether-based electrolytes also show that Examples 1, 3, and 4 have higher capacity and more stable cycling performance. After 400 cycles at 0.1 A / g, their capacity retention rates are 95.6%, 89.6%, and 90.66%, respectively, which are much higher than the 72.4% of Comparative Example 1. Examples 5-8 also achieved a capacity retention rate of about 73-81%, reaching a high capacity of 172-214 mAh / g at 0.3 A / g. The above data indicate that doping and modifying hard carbon anodes with bismuth-containing or nitrogen-containing precursors or a combination of both can effectively improve their sodium storage performance.
[0046] In summary, this invention enhances the interface of hard carbon materials by doping with bismuth- or nitrogen-containing precursors. The doped elements promote the formation of a high-strength solid electrolyte interface (SEI) rich in LiF during the sodium formation process. The introduction of nitrogen introduces Na3N into the SEI, thereby enhancing the interfacial ion diffusion efficiency. Meanwhile, the low-melting-point Bi can be doped into the interior of the hard carbon material, expanding the carbon interlayer spacing to improve the mass transfer rate of the bulk phase. It can also promote the filling process of sodium in the voids inside the hard carbon, thus comprehensively improving the rate capability and cycle stability of the hard carbon anode.
[0047] The high-performance interface-controlled hard carbon anode material described in this invention significantly improves battery performance through a simple processing method, has good application value, and is suitable for industrial promotion and application.
[0048] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the embodiments and descriptions in the specification are merely illustrative.
[0049] The principles of this invention can be varied and modified in many ways without departing from its spirit and scope, and all such variations and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing high-performance interface-controlled hard carbon materials, characterized in that, Includes the following steps: 1) Mix bismuth- or nitrogen-containing precursors and hard carbon materials in a certain proportion, and then directly dry-mill or wet-mill and dry to obtain mixture I; 2) Mixture I was heated to a certain temperature under an inert atmosphere and a certain pressure to undergo high-temperature doping heat treatment, and then cooled to room temperature to obtain a high-performance interface-controlled hard carbon material.
2. The method for preparing high-performance interface-controlled hard carbon materials as described in claim 1, characterized in that, In step 1), the hard carbon material is biomass-based hard carbon, polymer-based hard carbon, or fossil fuel-based hard carbon material, wherein the median particle size D50 of the hard carbon particles is 0.05-20 μm; the bismuth- or nitrogen-containing precursor is one or a mixture of two or more of the following: bismuth powder, bismuth nitrate, bismuth subnitrate, bismuth oxide, bismuth citrate, bismuth ammonium citrate, bismuth carbonate, bismuth trichloride, bismuth sulfate, bismuth titanate, bismuth phosphate, ammonium citrate, glycine, ammonium fluoride, ammonium nitrate, and ammonium sulfide.
3. The method for preparing high-performance interface-controlled hard carbon materials as described in claim 1, characterized in that, In step 1), the mixing mass ratio of hard carbon material and precursor is 200:1 to 1:20; during wet milling, the solution used is one or more of water, acetonitrile, methanol, propanol, acetone, ethanol, NMP, DMSO, and DMS, and the mass ratio of the dry mixture of nitrogen-containing precursor and hard carbon material to the solution in the wet mixing is 200:1 to 1:200; the drying operation after wet mixing is: keeping at 50℃ to 150℃ for 0.5 to 24 hours.
4. The method for preparing high-performance interface-controlled hard carbon materials as described in claim 1, characterized in that, In step 1), the equipment used for mixing is a high-speed ball mill, a horizontal ball mill, a stirred ball mill, a VC type mixing equipment, or a V type mixing equipment. The mixing time is 0.02 to 12 hours, and the rotation speed is 50 to 2000 rpm.
5. The method for preparing high-performance interface-controlled hard carbon materials as described in claim 1, characterized in that, In step 2), the inert atmosphere is formed by one or more of nitrogen, argon, and helium; the gas flow rate under the inert atmosphere is 0.2 to 10 L / min, and the ventilation time is 0.1 to 20 h.
6. The method for preparing high-performance interface-controlled hard carbon materials as described in claim 1, characterized in that, In step 2), the pressure of the high-temperature doping heat treatment is 0.9 to 1.2 atmospheres; the high-temperature doping process is as follows: heating at a heating rate of 1 to 10 °C / min, and holding at 200 °C to 1000 °C for 0.01 to 5 hours.
7. High-performance interface-controlled hard carbon materials prepared by any of the methods described in claims 1-6.
8. The application of the high-performance interface-controlled hard carbon material as described in claim 7 in the preparation of composite electrode slurry, sodium-ion battery, or sodium-ion secondary battery.
9. A method for preparing composite electrode paste using the high-performance interface-controlled hard carbon material as described in claim 7, characterized in that, Includes the following steps: a) Weigh a certain amount of active material, conductive agent and binder, and place the three in a container in sequence to obtain a mixed powder; the active material is a high-performance interface-controlled hard carbon material prepared by the above method. b) Preparation of the mixed slurry: Add solvent to the mixed powder in step a), ultrasonically disperse at a power of 50-120 W for 5-15 min, and stir at a speed of 200-800 r / min for 3-24 h to make the active material and conductive agent evenly dispersed, and obtain the composite electrode slurry.
10. A method for preparing sodium-ion batteries or sodium-ion secondary batteries using the high-performance interface-controlled hard carbon anode material as described in claim 7, characterized in that, Includes the following steps: S1. Preparation of electrode sheet: A composite electrode slurry is prepared by using high-performance interface-controlled hard carbon anode material, coated on the current collector, dried at 50~150℃ for 4~24h, and then made into a button electrode sheet with a diameter of 10-16 mm using a punch. S2. Button cell assembly: Select a suitable counter electrode and assemble it into a button cell.