Preparation method and application of sodium-ion battery anode material based on bismuth-expanded graphite composite

Abstract

This invention discloses a method for preparing and applying a sodium-ion battery anode material based on a bismuth-expanded graphite composite, belonging to the field of battery material technology. The method includes the following steps: S1, bismuth nitrate pentahydrate and 1,3,5-benzenetricarboxylic acid are placed in a beaker, followed by the addition of N,N-dimethylformamide and methanol; the mixture is ultrasonically stirred for 5 minutes and then stirred for 15 minutes, followed by the addition of expanded graphite to obtain a mixed solution; S2, the mixed solution is poured into a hydrothermal reactor for hydrothermal reaction to obtain a bismuth-metal-organic framework / expanded graphite composite material precursor; S3, the bismuth-metal-organic framework / expanded graphite composite material precursor is placed in an alumina ceramic boat, a ceramic boat lid is attached, and a carbonization reaction is carried out under a nitrogen atmosphere. After the reaction is completed, the mixture is naturally cooled to room temperature to obtain the bismuth-expanded graphite composite material. This invention, based on a bismuth-expanded graphite composite, provides a sodium-ion battery anode material. The introduction of the expanded graphite carbon framework improves the ionic and electronic conductivity of the bismuth-based material and accelerates the kinetics.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, and in particular to the preparation method and application of sodium-ion battery anode materials based on bismuth-expanded graphite composites. Background Technology

[0002] The synergistic development of the energy storage industry and AI big data is ushering in unprecedented opportunities. With the exponential growth in demand for AI computing power, the energy storage industry, through its robust energy supply security system, provides crucial foundational support for AI technological advancements. Energy storage systems comprise multiple components, with energy storage devices being the core. Lithium-ion batteries are currently the most commercially viable energy storage devices, but lithium dendrite penetration through the separator and the dwindling lithium resources severely limit their further development. Sodium-ion batteries, due to their similar physical and chemical properties to lithium-ion batteries and abundant sodium resources, have become a promising alternative. While the development of sodium-ion batteries is indeed exciting, some significant challenges remain. For example, sodium-ion batteries suffer from limited energy density, insufficient rate performance, and insufficient cycle life. Furthermore, the preparation and production of electrode materials often involves complex processes, significant environmental pollution, and low raw material utilization, resulting in substantial waste.

[0003] Given the various challenges faced by sodium-ion battery electrode materials, developing a simple and efficient preparation process while improving their rate performance and cycle performance has become a problem that needs to be solved in the research of sodium-ion battery electrode materials. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying sodium-ion battery anode materials based on bismuth-expanded graphite composites, in order to solve the above-mentioned problems.

[0005] This invention provides a method for preparing a sodium-ion battery anode material based on a bismuth-expanded graphite composite, comprising the following steps:

[0006] S1. Place bismuth nitrate pentahydrate and 1,3,5-benzenetricarboxylic acid into a beaker, then add N,N-dimethylformamide and methanol; sonicate for 5 minutes and stir for 15 minutes. After stirring, add expanded graphite and stir for another 15 minutes to obtain a mixture.

[0007] S2. Pour the mixture into a hydrothermal reactor for hydrothermal reaction. After the reaction is complete, centrifuge and dry the solution to obtain the bismuth-metal-organic framework / expanded graphite composite material precursor.

[0008] S3. Place the bismuth-metal-organic framework / expanded graphite composite precursor in an alumina ceramic boat and attach a ceramic boat cover. Purge with nitrogen for five minutes to remove air, and then carry out a carbonization reaction under a nitrogen atmosphere. After the reaction is completed, allow it to cool naturally to room temperature to obtain the bismuth-expanded graphite composite material.

[0009] Preferably, in the above-mentioned method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite, the volume ratio of N,N-dimethylformamide and methanol in step S1 is 1:3.

[0010] Preferably, in the above-mentioned method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite, the hydrothermal reaction temperature in step S2 is 120°C and the reaction time is 12 h.

[0011] Preferably, in the above-mentioned method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite, the reaction conditions for the carbonization reaction in step S3 are: heating to 800°C at a rate of 5°C / min and holding at that temperature for 2 hours.

[0012] Preferably, in the above-mentioned method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite, the preparation steps of the expanded graphite added in step S1 are as follows:

[0013] a. Weigh waste graphite and sodium nitrate in a weight ratio of 1:3, put them into a beaker, add a small amount of concentrated sulfuric acid, and then stir in an ice bath for 1 hour.

[0014] b. During the ice bath stirring process, 3 g of potassium permanganate was added to the beaker in ten equal portions at different times. After the ice bath stirring was completed, acidified graphite was obtained.

[0015] c. Acidified graphite is stirred in an oil bath to obtain intercalated graphite. Then, an appropriate amount of deionized water is added and the temperature is raised to obtain high-temperature intercalated graphite.

[0016] d. Add high-temperature intercalated graphite to diluted hydrogen peroxide solution and react for 5-10 minutes. Let stand for half an hour, then centrifuge. After centrifugation, the expanded graphite precursor is obtained.

[0017] e. Place the obtained expanded graphite precursor in an alumina ceramic boat, attach a ceramic boat cover, introduce nitrogen gas for five minutes to purge air, and then carry out a carbonization reaction under a nitrogen atmosphere. After naturally cooling to room temperature, expanded graphite is obtained.

[0018] Preferably, in the above-mentioned method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite, the oil bath conditions for obtaining intercalated graphite by acidification graphite reaction in step c are 35°C for 2 h; the reaction conditions for obtaining high-temperature intercalated graphite by intercalation graphite reaction are heating to 98°C and holding for 0.5 h.

[0019] Preferably, in the above-mentioned method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite, the reaction conditions for the carbonization reaction in step e are: heating to 900°C at a rate of 10°C / min and holding at that temperature for 3 hours.

[0020] This invention provides an application of the bismuth-expanded graphite composite obtained by the above preparation method as a negative electrode material for sodium-ion batteries. The preparation steps of the sodium-ion battery negative electrode are as follows: grinding the bismuth-expanded graphite composite material, Ketjen black and sodium carboxymethyl cellulose in a mass ratio of 7:2:1, adding ultrapure water to make a slurry, and coating it on copper foil to make an electrode sheet.

[0021] Preferably, in the application of the above-mentioned bismuth-expanded graphite composite as a negative electrode material for sodium-ion batteries, the assembly steps for preparing the sodium-ion battery using the electrode sheet are as follows: using the electrode sheet and sodium sheet as positive and negative electrodes, glass fiber membrane as separator, and 1 mol / L sodium hexafluorophosphate diethylene glycol dimethyl ether solution as electrolyte, a button battery is assembled.

[0022] Therefore, by employing the above-mentioned preparation method and application of sodium-ion battery anode material based on bismuth-expanded graphite composite, the present invention achieves the following beneficial effects:

[0023] (1) The bismuth-composite expanded graphite material prepared by this invention is a multifunctional composite material derived from a metal-organic framework and recycled expanded graphite composite as a precursor. By recycling and reusing waste graphite, not only is resource recycling achieved to reduce environmental pollution, but production costs are also significantly reduced, thus combining environmental benefits and economic advantages.

[0024] (2) By introducing an expanded graphite framework, the conductivity of bismuth-based materials can be significantly improved and ion diffusion kinetics accelerated, thereby endowing them with excellent rate performance and high power output characteristics. In addition, the three-dimensional network structure of expanded graphite effectively buffers the volume change during sodium ion insertion / extraction, enhances structural stability, and enables the electrode material to exhibit excellent tolerance during high-current charge-discharge cycles. As a negative electrode material, this composite material can be cycled 5000 times at a high current density of 10 A / g (25.9C) with almost no loss in capacity retention, fully demonstrating its long-term stability and potential for high-power applications. It also has good reversible capacity under low-temperature conditions, indicating that it has good low-temperature resistance.

[0025] (3) The preparation method of the present invention mainly consists of two steps: the first step is solvothermal treatment, and the second step is annealing. Solvothermal treatment only requires increasing the size of the hydrothermal reactor to achieve mass production; annealing only requires increasing the size of the tube furnace to achieve one-step annealing of kilogram-level materials. The preparation method of the present invention is easy to achieve mass production, the preparation method is simple, and it can be synthesized in a short time.

[0026] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0027] Figure 1 The images show the XRD patterns of the anode materials obtained in Examples 1 and 2 of the present invention, which describe the preparation method and application of sodium-ion battery anode materials based on bismuth-expanded graphite composites.

[0028] Figure 2 The images show SEM images of the anode materials obtained in Examples 1 and 2 of the present invention, which describe the preparation method and application of sodium-ion battery anode materials based on bismuth-expanded graphite composites.

[0029] Figure 3 Examples 1 and 2 of the present invention provide the rate performance diagrams and cycle performance diagrams under different current density conditions of sodium-ion battery obtained from the preparation method and application of sodium-ion battery anode material based on bismuth-expanded graphite composite. Among them, (a) is the rate performance diagram, (b) is the cycle performance diagram at a current density of 0.1 A / g, and (c) is the cycle performance diagram at a current density of 10 A / g.

[0030] Figure 4 This is a rate performance diagram of a sodium-ion battery under different low-temperature conditions, representing Example 1 of the present invention, which describes the preparation method and application of a sodium-ion battery anode material based on bismuth-expanded graphite composite. Detailed Implementation

[0031] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0033] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0034] This invention provides a method for preparing a sodium-ion battery anode material based on a bismuth-expanded graphite composite, comprising the following steps:

[0035] S1. Place bismuth nitrate pentahydrate and 1,3,5-benzenetricarboxylic acid into a beaker, then add N,N-dimethylformamide and methanol; sonicate for 5 minutes and stir for 15 minutes. After stirring, add expanded graphite and stir for another 15 minutes to obtain a mixture.

[0036] S2. Pour the mixture into a hydrothermal reactor for hydrothermal reaction. After the reaction is complete, centrifuge and dry the solution to obtain the bismuth-metal-organic framework / expanded graphite composite material precursor.

[0037] S3. Place the bismuth-metal-organic framework / expanded graphite composite precursor in an alumina ceramic boat and attach a ceramic boat cover. Purge with nitrogen for five minutes to remove air, and then carry out a carbonization reaction under a nitrogen atmosphere. After the reaction is completed, allow it to cool naturally to room temperature to obtain the bismuth-expanded graphite composite material.

[0038] To further optimize the above technical solution, the volume ratio of N,N-dimethylformamide to methanol in step S1 is 1:3.

[0039] To further optimize the above technical solution, the hydrothermal reaction temperature in step S2 is 120℃ and the reaction time is 12 h.

[0040] To further optimize the above technical solution, the reaction conditions for the carbonization reaction in step S3 are to heat to 800℃ at a rate of 5℃ / min and hold for 2 hours.

[0041] To further optimize the above technical solution, the preparation steps of the expanded graphite added in step S1 are as follows:

[0042] a. Weigh waste graphite and sodium nitrate in a weight ratio of 1:3, put them into a beaker, add a small amount of concentrated sulfuric acid, and then stir in an ice bath for 1 hour.

[0043] b. During the ice bath stirring process, 3 g of potassium permanganate was added to the beaker in ten equal portions at different times. After the ice bath stirring was completed, acidified graphite was obtained.

[0044] c. Acidified graphite is stirred in an oil bath to obtain intercalated graphite. Then, an appropriate amount of deionized water is added and the temperature is raised to obtain high-temperature intercalated graphite.

[0045] d. Add high-temperature intercalated graphite to diluted hydrogen peroxide solution and react for 5-10 minutes. Let stand for half an hour, then centrifuge. After centrifugation, the expanded graphite precursor is obtained.

[0046] e. Place the obtained expanded graphite precursor in an alumina ceramic boat, attach a ceramic boat cover, introduce nitrogen gas for five minutes to purge air, and then carry out a carbonization reaction under a nitrogen atmosphere. After naturally cooling to room temperature, expanded graphite is obtained.

[0047] To further optimize the above technical solution, the oil bath conditions for obtaining intercalated graphite by acidification graphite reaction in step c are 35℃ for 2 h; the reaction conditions for obtaining high-temperature intercalated graphite by intercalation graphite reaction are heating to 98℃ and holding for 0.5 h.

[0048] To further optimize the above technical solution, the reaction conditions for the carbonization reaction in step e are: heating to 900℃ at a rate of 10℃ / min and holding at that temperature for 3 hours.

[0049] This invention provides an application of the bismuth-expanded graphite composite obtained by the above preparation method as a negative electrode material for sodium-ion batteries. The preparation steps of the sodium-ion battery negative electrode are as follows: grinding the bismuth-expanded graphite composite material, Ketjen black and sodium carboxymethyl cellulose in a mass ratio of 7:2:1, adding ultrapure water to make a slurry, and coating it on copper foil to make an electrode sheet.

[0050] To further optimize the above technical solution, the assembly steps for preparing a sodium-ion battery using the electrode sheet are as follows: using the electrode sheet and sodium sheet as positive and negative electrodes, a glass fiber membrane as a separator, and a 1 mol / L sodium hexafluorophosphate diethylene glycol dimethyl ether solution as an electrolyte, a button cell is assembled.

[0051] To more clearly and in detail introduce the preparation method and application of sodium-ion battery anode material based on bismuth-expanded graphite composite provided in the embodiments of the present invention, the following description will be based on specific embodiments.

[0052] Example 1

[0053] 708 mg of bismuth nitrate pentahydrate and 579 mg of 1,3,5-benzenetricarboxylic acid were placed in a beaker, followed by 7.5 mL of N,N-dimethylformamide and 22.5 mL of methanol. The mixture was sonicated for 5 minutes and then stirred for 15 minutes. After stirring, 64.4 mg of expanded graphite was added, and the mixture was stirred for another 15 minutes. The resulting mixture was poured into the inner liner of a hydrothermal reactor and reacted at 120 °C for 12 h. After the reaction, the solution was centrifuged and dried to obtain the precursor. The precursor was placed in an alumina ceramic boat, covered with a lid, and purged with nitrogen for 5 minutes to remove air. The temperature was then increased to 800 °C at a rate of 5 °C / min under a nitrogen atmosphere and held for 2 h. After natural cooling to room temperature, the bismuth-expanded graphite composite material was obtained.

[0054] The obtained bismuth-expanded graphite composite material, Ketjen black, and sodium carboxymethyl cellulose were ground in a mass ratio of 7:2:1, and ultrapure water was added to make a slurry. The slurry was coated on copper foil to make an electrode sheet. The electrode sheet and sodium sheet were used as the positive and negative electrodes, a glass fiber membrane was used as the separator, and a 1 mol / L sodium hexafluorophosphate diethylene glycol dimethyl ether solution was used as the electrolyte to assemble a button battery.

[0055] Example 2

[0056] 708 mg of bismuth nitrate pentahydrate and 579 mg of 1,3,5-benzenetricarboxylic acid were placed in a beaker, followed by 7.5 mL of N,N-dimethylformamide and 22.5 mL of methanol. The mixture was sonicated for 5 minutes and then stirred for 15 minutes. The resulting mixture was poured into the inner liner of a hydrothermal reactor and reacted at 120 °C for 12 h. After the reaction, the solution was centrifuged and dried to obtain the precursor. The precursor was placed in an alumina ceramic boat, covered with a lid, and purged with nitrogen for 5 minutes to remove air. The temperature was then increased to 800 °C at a rate of 5 °C / min under a nitrogen atmosphere and held for 2 h. After natural cooling to room temperature, the bismuth-based material was obtained.

[0057] The obtained bismuth-based material, Ketjen black, and sodium carboxymethyl cellulose were ground in a mass ratio of 7:2:1, and ultrapure water was added to make a slurry. The slurry was then coated onto copper foil to form an electrode sheet. The electrode sheet and sodium sheet were used as the positive and negative electrodes, a glass fiber membrane was used as the separator, and a 1 mol / L sodium hexafluorophosphate diethylene glycol dimethyl ether solution was used as the electrolyte to assemble a button battery.

[0058] The negative electrode materials obtained in Examples 1 and 2 were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), such as... Figure 1-2 As shown, the rate performance and cycle performance of the negative electrode material under different conditions were tested, such as... Figure 3-4As shown, the introduction of the expanded graphite carbon framework improves the electrical conductivity of bismuth-based materials and accelerates the cycling kinetics. Simultaneously, the expanded graphite framework effectively mitigates the volume change of bismuth-based materials during sodium insertion / deintercalation, thus giving the bismuth-expanded graphite composite material superior cycling performance. Figure 3 As can be seen in (a), the rate performance of the bismuth-expanded graphite composite material of Example 1 hardly decreased before 30 A / g, and it can be charged and discharged at high rates. It only takes 11 s to complete a charge and discharge cycle at a current of 100 A / g. In low current cycling, the bismuth-expanded graphite composite material of Example 1 also showed a higher reversible capacity than the bismuth-based material in Example 2. Figure 3 (c) In the high current cycling, Example 1 showed almost no capacity decay after 5000 cycles at 10 A / g, while Example 2 only had about 90% capacity retention after about 3600 cycles.

[0059] Therefore, this invention employs the aforementioned method for preparing sodium-ion battery anode materials based on bismuth-expanded graphite composites. The prepared bismuth-composite expanded graphite material is a multifunctional composite material formed by combining metal-organic framework derivatives as precursors with recycled expanded graphite. By recycling and reusing waste graphite, not only is resource recycling achieved to reduce environmental pollution, but production costs are also significantly reduced, combining environmental benefits with economic advantages. Introducing the expanded graphite framework significantly improves the conductivity of bismuth-based materials and accelerates ion diffusion kinetics, thereby endowing them with excellent rate performance and high power output characteristics. Furthermore, the three-dimensional network structure of expanded graphite effectively buffers volume changes during sodium ion insertion / extraction, enhancing structural stability and enabling the electrode material to exhibit excellent tolerance during high-current charge-discharge cycles. As an anode material, this composite material maintains almost no capacity loss after 5000 cycles at a high current density of 10 A / g (25.9C), fully demonstrating its long-term stability and potential for high-power applications. It also exhibits good reversible capacity under low-temperature conditions, indicating good low-temperature resistance. The preparation method mainly consists of two steps: solvothermal treatment and annealing. Solvothermal treatment only requires increasing the size of the hydrothermal reactor to achieve mass production; annealing only requires increasing the size of the tube furnace to achieve one-step annealing of kilogram-level materials. The preparation method of this invention is easy to mass-produce, simple, and allows for short-time synthesis.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite, characterized in that, Includes the following steps: S1. Place bismuth nitrate pentahydrate and 1,3,5-benzenetricarboxylic acid into a beaker, then add N,N-dimethylformamide and methanol; sonicate for 5 minutes and stir for 15 minutes. After stirring, add expanded graphite and stir for another 15 minutes to obtain a mixture. S2. Pour the mixture into a hydrothermal reactor for hydrothermal reaction. After the reaction is complete, centrifuge and dry the solution to obtain the bismuth-metal-organic framework / expanded graphite composite material precursor. S3. Place the bismuth-metal-organic framework / expanded graphite composite precursor in an alumina ceramic boat and attach a ceramic boat cover. Purge with nitrogen for five minutes to remove air, and then carry out a carbonization reaction under a nitrogen atmosphere. After the reaction is completed, allow it to cool naturally to room temperature to obtain the bismuth-expanded graphite composite material.

2. The method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite according to claim 1, characterized in that, In step S1, the volume ratio of N,N-dimethylformamide to methanol is 1:

3.

3. The method for preparing the sodium-ion battery anode material based on bismuth-expanded graphite composite according to claim 1, characterized in that, In step S2, the hydrothermal reaction temperature is 120℃ and the reaction time is 12 h.

4. The method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite according to claim 1, characterized in that, The carbonization reaction conditions in step S3 are: heating to 800°C at a rate of 5°C / min and holding at that temperature for 2 hours.

5. The method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite according to claim 1, characterized in that, The preparation steps of the expanded graphite added in step S1 are as follows: a. Weigh waste graphite and sodium nitrate in a weight ratio of 1:3, put them into a beaker, add a small amount of concentrated sulfuric acid, and then stir in an ice bath for 1 hour. b. During the ice bath stirring process, 3 g of potassium permanganate was added to the beaker in ten equal portions at different times. After the ice bath stirring was completed, acidified graphite was obtained. c. Acidified graphite is stirred in an oil bath to obtain intercalated graphite. Then, an appropriate amount of deionized water is added and the temperature is raised to obtain high-temperature intercalated graphite. d. Add high-temperature intercalated graphite to diluted hydrogen peroxide solution and react for 5-10 minutes. Let stand for half an hour, then centrifuge. After centrifugation, the expanded graphite precursor is obtained. e. Place the obtained expanded graphite precursor in an alumina ceramic boat, attach a ceramic boat cover, introduce nitrogen gas for five minutes to purge air, and then carry out a carbonization reaction under a nitrogen atmosphere. After naturally cooling to room temperature, expanded graphite is obtained.

6. The method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite according to claim 5, characterized in that, In step c, the oil bath conditions for the acidified graphite reaction to obtain intercalated graphite are 35℃ for 2 h; the reaction conditions for the intercalated graphite reaction to obtain high-temperature intercalated graphite are heating to 98℃ and holding for 0.5 h.

7. The method for preparing sodium-ion battery anode material based on bismuth-expanded graphite composite according to claim 5, characterized in that, The carbonization reaction conditions in step e are: heating to 900°C at a rate of 10°C / min and holding at that temperature for 3 hours.

8. A sodium-ion battery anode material based on a bismuth-expanded graphite composite, obtained by the preparation method according to any one of claims 1-7, is used to prepare a sodium-ion battery anode, characterized in that, The preparation steps of the sodium-ion battery negative electrode are as follows: bismuth-expanded graphite composite material, Ketjen black and sodium carboxymethyl cellulose are ground in a mass ratio of 7:2:1, ultrapure water is added to make a slurry, and the slurry is coated on copper foil to make an electrode sheet.

9. The sodium-ion battery anode material based on bismuth-expanded graphite composite according to claim 8 is used to prepare a sodium-ion battery anode, characterized in that, The assembly steps for preparing a sodium-ion battery using the prepared electrode sheet are as follows: using the electrode sheet and sodium sheet as positive and negative electrodes, a glass fiber membrane as a separator, and a 1 mol / L sodium hexafluorophosphate diethylene glycol dimethyl ether solution as an electrolyte, a button cell is assembled.

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