Porous carbon negative electrode material, preparation method thereof and secondary battery

Abstract

The present application relates to the technical field of energy storage equipment, and particularly relates to a porous carbon negative electrode material, a preparation method thereof and a secondary battery, the preparation method comprising the following process: starch is mixed with a template pore-forming agent, and a reaction is carried out under subcritical water conditions to obtain the porous carbon negative electrode material. The preparation method of the porous carbon negative electrode material provided by the present application utilizes subcritical water synthesis technology, simplifies the preparation process of the traditional porous carbon negative electrode material, is conducive to reducing energy consumption and cost, and realizes efficient preparation of the porous carbon material; the obtained porous carbon negative electrode material exhibits excellent electrochemical performance in the secondary battery, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of energy storage equipment technology, and in particular to a porous carbon anode material, its preparation method, and a secondary battery. Background Technology

[0002] With the rapid development of new energy vehicles and renewable energy, the demand for high-performance energy storage materials is increasing. Porous carbon materials, due to their high specific surface area, excellent conductivity, and good cycle stability, have become a research focus for anode materials in rechargeable batteries such as lithium-ion and sodium-ion batteries. Porous carbon materials prepared using biomass as raw material possess excellent electrochemical performance and stable structure, and have broad application prospects in the field of rechargeable batteries.

[0003] Starch, as a typical representative of polysaccharides, has the advantages of low price, abundant sources, and simple composition, making it an ideal precursor for preparing porous carbon materials. Traditional methods for preparing starch-based porous carbon materials, such as high-temperature pyrolysis and chemical vapor deposition, all suffer from complex processing issues.

[0004] Therefore, how to provide a simple preparation method for starch-based porous carbon materials is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the complexity of the preparation process for starch-based porous carbon materials in existing technologies, this invention provides a method for preparing porous carbon materials. This method uses subcritical water as a solvent and combines it with appropriate template removal techniques to prepare porous carbon anode materials with excellent electrochemical performance, thus solving the problem of the complexity of the preparation process for starch-based porous carbon materials in existing technologies.

[0006] The technical solution adopted by this invention to solve its technical problem is: A method for preparing a porous carbon anode material includes the following steps: mixing starch with a template pore-forming agent and reacting under subcritical water conditions to obtain the porous carbon anode material.

[0007] Optionally, the temperature range of the subcritical water conditions is 180-250℃, and the pressure is 10-30MPa.

[0008] Optionally, the template pore-forming agent is a metal chloride.

[0009] Optionally, the template pore-forming agent is lithium chloride or sodium chloride.

[0010] Optionally, the mass ratio of the starch to the template pore-forming agent is 1:(4-6).

[0011] Optionally, the starch is dried starch.

[0012] Optionally, the starch is selected from at least one of cereal starch, potato starch, and legume starch.

[0013] Another object of the present invention is to provide a porous carbon anode material, which is prepared by the method for preparing porous carbon anode materials as described above.

[0014] Another object of the present invention is to provide a secondary battery comprising the porous carbon anode material as described above.

[0015] Optionally, the secondary battery is a lithium-ion battery or a sodium-ion battery.

[0016] The beneficial effects of this invention are: The method for preparing porous carbon anode materials provided by this invention utilizes subcritical water synthesis technology, which simplifies the traditional preparation process of porous carbon anode materials, helps to reduce energy consumption and cost, and achieves efficient preparation of porous carbon materials. The resulting porous carbon anode materials exhibit excellent electrochemical performance in secondary batteries and have broad application prospects. Detailed Implementation

[0017] The present invention will now be described in further detail. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0018] To address the problem of complex preparation processes for starch-based porous carbon materials in existing technologies, this invention provides a method for preparing porous carbon anode materials. The method includes the following steps: mixing starch with a template pore-forming agent and reacting the mixture under subcritical water conditions to obtain porous carbon anode materials.

[0019] Starch is a highly crystalline substance with numerous hydrogen bonds between and within molecules, making it difficult to dissolve in water. Traditional processes for preparing carbon anode materials from starch are prone to particle agglomeration and clumping, affecting the electrochemical performance of the anode material. This invention introduces subcritical water, providing space for Brownian motion in the product, effectively mitigating particle agglomeration and clumping caused by precursor carbonization and promoting porous formation. During the reaction, starch decomposes and reorganizes in subcritical water, while a template pore-forming agent helps the precursor form a porous structure, resulting in a porous carbon anode material with excellent electrochemical performance.

[0020] The method for preparing porous carbon anode materials provided by this invention utilizes subcritical water synthesis technology, which simplifies the traditional preparation process of porous carbon anode materials, helps to reduce energy consumption and cost, and achieves efficient preparation of porous carbon materials. The resulting porous carbon anode materials exhibit excellent electrochemical performance in secondary batteries and have broad application prospects.

[0021] To balance preparation efficiency and electrochemical performance of porous carbon anode materials, the present invention preferably uses a subcritical water condition with a temperature range of 180-250℃ and a pressure of 10-30MPa; and further preferably uses a reaction time of 8-12h.

[0022] To ensure the formation of a porous structure in the carbon anode material, the present invention preferably uses a metal chloride as the template pore-forming agent, so as to facilitate pore formation during the reaction process.

[0023] To further improve the electrochemical performance of porous carbon anode materials, the present invention preferably uses lithium chloride or sodium chloride as the template pore-forming agent. Specifically, when the porous carbon anode material is used in lithium-ion batteries, lithium chloride is preferred as the template pore-forming agent, so that while the lithium chloride is used as the template pore-forming agent to create pores in the precursor, lithium ions can enter the pore structure of the porous carbon and participate in the pre-lithiation effect of the subsequent charge and discharge process. Similarly, when the porous carbon anode material is used in sodium-ion batteries, sodium chloride is preferred as the template pore-forming agent, so that while the sodium chloride is used as the template pore-forming agent to create pores in the precursor, sodium ions can enter the pore structure of the porous carbon and participate in the pre-sodiumization effect of the subsequent charge and discharge process.

[0024] This invention selects lithium chloride or sodium chloride as a template pore-forming agent, so that the lithium chloride / sodium chloride can be used as a template pore-forming agent, and the residue after cleaning can be used as a pre-lithiation / pre-sodiumization salt, thus achieving dual functions with one product.

[0025] To balance the structural stability and electrochemical performance of the porous carbon anode material, the present invention preferably uses a mass ratio of starch to the template pore-forming agent of 1:(4-6); preferably, the starch is dried starch, and more preferably, the drying process of the starch is as follows: the starch is placed under vacuum and kept at 60°C for 10 hours.

[0026] The starch used in this invention is preferably selected from at least one of cereal starch, potato starch, and legume starch.

[0027] Specifically, the preparation method of the porous carbon anode material in this invention can be carried out according to the following steps: S1. The starch was dried under vacuum at 60°C for 10 hours to obtain dried starch; S2. The dried starch and template pore-forming agent are added to the subcritical water reactor at a mass ratio of 1:(4-6). The reaction is carried out under subcritical water conditions (temperature range of 180-250℃, pressure of 10-30MPa) for 10 hours to obtain a solid mixture. S3. The solid mixture after the reaction is ultrasonically cleaned in deionized water for 2-6 hours to remove excess template pore-forming agent. The remaining template pore-forming agent remains in the pore structure of the porous carbon and participates in the pre-lithiation / pre-sodiumization of the subsequent charge and discharge process to obtain the target product of the present invention, porous carbon anode material.

[0028] Another object of the present invention is to provide a porous carbon anode material, which is prepared by the method for preparing porous carbon anode materials as described above.

[0029] The porous carbon anode material provided by this invention introduces subcritical water synthesis technology in its preparation process, which simplifies the traditional preparation process of porous carbon anode materials, helps to reduce energy consumption and cost, and realizes the efficient preparation of porous carbon materials. The resulting porous carbon anode material exhibits excellent electrochemical performance in secondary batteries and has broad application prospects.

[0030] Another object of the present invention is to provide a secondary battery, characterized in that it comprises the porous carbon anode material as described above.

[0031] The secondary battery provided by this invention uses a porous carbon anode material, which incorporates subcritical water synthesis technology during the preparation process. This simplifies the traditional preparation process of porous carbon anode materials, reduces energy consumption and costs, and achieves efficient preparation of porous carbon materials. The resulting porous carbon anode material exhibits excellent electrochemical performance in secondary batteries and has broad application prospects.

[0032] Specifically, the secondary battery in this invention is a lithium-ion battery or a sodium-ion battery.

[0033] Furthermore, when the secondary battery is a lithium-ion battery, lithium chloride is used as a template pore-forming agent in the preparation process of porous carbon anode material; when the secondary battery is a sodium-ion battery, sodium chloride is used as a template pore-forming agent in the preparation process of porous carbon anode material.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0035] Example 1 This embodiment provides a method for preparing a porous carbon anode material, including the following steps: S1. Corn starch was dried under vacuum at 60°C for 10 hours to obtain dried starch; S2. The dried starch and LiCl were added to a subcritical water reactor at a mass ratio of 1:4. The reaction was carried out under subcritical water conditions (temperature 200℃, pressure 20MPa) for 10 hours to obtain a solid mixture. S3. The solid mixture after the reaction is ultrasonically cleaned in deionized water for 4 hours to remove excess template pore-forming agent LiCl. The remaining template pore-forming agent LiCl remains in the pore structure of the porous carbon and participates in the pre-lithiation effect of the subsequent charge and discharge process to obtain the target product of the present invention, porous carbon anode material.

[0036] The specific surface area of ​​the target product was measured using a specific surface area analyzer, and the test results are shown in Table 1.

[0037] Example 2 This embodiment provides a method for preparing a porous carbon anode material, including the following steps: S1. Wheat starch was dried under vacuum at 60°C for 10 hours to obtain dried starch; S2. The dried starch and LiCl were added to a subcritical water reactor at a mass ratio of 1:6. The reaction was carried out under subcritical water conditions (temperature 200℃, pressure 20MPa) for 10 hours to obtain a solid mixture. S3. The solid mixture after the reaction is ultrasonically cleaned in deionized water for 4 hours to remove excess template pore-forming agent LiCl. The remaining template pore-forming agent LiCl remains in the pore structure of the porous carbon and participates in the pre-lithiation effect of the subsequent charge and discharge process to obtain the target product of the present invention, porous carbon anode material.

[0038] The specific surface area of ​​the target product was measured using a specific surface area analyzer, and the test results are shown in Table 1.

[0039] Example 3 This embodiment provides a method for preparing a porous carbon anode material, including the following steps: S1. Corn starch was dried under vacuum at 60°C for 10 hours to obtain dried starch; S2. The dried starch and LiCl were added to a subcritical water reactor at a mass ratio of 1:4. The reaction was carried out under subcritical water conditions (temperature 180℃, pressure 30MPa) for 10 hours to obtain a solid mixture. S3. The solid mixture after the reaction is ultrasonically cleaned in deionized water for 4 hours to remove excess template pore-forming agent LiCl. The remaining template pore-forming agent LiCl remains in the pore structure of the porous carbon and participates in the pre-lithiation effect of the subsequent charge and discharge process to obtain the target product of the present invention, porous carbon anode material.

[0040] The specific surface area of ​​the target product was measured using a specific surface area analyzer, and the test results are shown in Table 1.

[0041] Example 4 This embodiment provides a method for preparing a porous carbon anode material, including the following steps: S1. Corn starch was dried under vacuum at 60°C for 10 hours to obtain dried starch; S2. The dried starch and LiCl were added to a subcritical water reactor at a mass ratio of 1:4. The reaction was carried out under subcritical water conditions (temperature 250℃, pressure 10MPa) for 10 hours to obtain a solid mixture. S3. The solid mixture after the reaction is ultrasonically cleaned in deionized water for 4 hours to remove excess template pore-forming agent LiCl. The remaining template pore-forming agent LiCl remains in the pore structure of the porous carbon and participates in the pre-lithiation effect of the subsequent charge and discharge process to obtain the target product of the present invention, porous carbon anode material.

[0042] The specific surface area of ​​the target product was measured using a specific surface area analyzer, and the test results are shown in Table 1.

[0043] Example 5 This embodiment provides a method for preparing a porous carbon anode material, including the following steps: S1. Potato starch was dried under vacuum at 60°C for 10 hours to obtain dried starch; S2. The dried starch and NaCl were added to a subcritical water reactor at a mass ratio of 1:6. The reaction was carried out under subcritical water conditions (temperature 200℃, pressure 20MPa) for 10 hours to obtain a solid mixture. S3. The solid mixture after the reaction is ultrasonically cleaned in deionized water for 4 hours to remove excess template pore-forming agent NaCl. The remaining template pore-forming agent NaCl remains in the pore structure of the porous carbon and participates in the pre-sodiumization effect of the subsequent charge and discharge process to obtain the target product of the present invention, porous carbon anode material.

[0044] The specific surface area of ​​the target product was measured using a specific surface area analyzer, and the test results are shown in Table 1.

[0045] Example 6 This embodiment provides a method for preparing a porous carbon anode material, including the following steps: S1. Sweet potato starch was dried under vacuum at 60°C for 10 hours to obtain dried starch; S2. The dried starch and NaCl were added to a subcritical water reactor at a mass ratio of 1:6. The reaction was carried out under subcritical water conditions (temperature 200℃, pressure 20MPa) for 10 hours to obtain a solid mixture. S3. The solid mixture after the reaction is ultrasonically cleaned in deionized water for 4 hours to remove excess template pore-forming agent NaCl. The remaining template pore-forming agent NaCl remains in the pore structure of the porous carbon and participates in the pre-sodiumization effect of the subsequent charge and discharge process to obtain the target product of the present invention, porous carbon anode material.

[0046] The specific surface area of ​​the target product was measured using a specific surface area analyzer, and the test results are shown in Table 1.

[0047] Comparative Example 1 This comparative example provides a method for preparing a porous carbon anode material, including the following steps: S1. Corn starch was dried under vacuum at 60°C for 10 hours to obtain dried starch; S2. The dried starch is added to a subcritical water reactor and reacted for 10 hours under subcritical water conditions (temperature 200℃, pressure 20MPa) to obtain the target product, the negative electrode material.

[0048] The specific surface area of ​​the target product was measured using a specific surface area analyzer, and the test results are shown in Table 1.

[0049] Comparative Example 2 This comparative example provides a method for preparing a porous carbon anode material, including the following steps: S1. Corn starch was dried under vacuum at 60°C for 10 hours to obtain dried starch; S2. Add the dried starch to a conventional hydrothermal reactor and react at 200°C for 10 hours to obtain the target product.

[0050] Under the reaction conditions provided in this comparative example, starch cannot be carbonized, and the resulting product cannot be used as a negative electrode material.

[0051] The negative electrode materials prepared in each embodiment and comparative example were fabricated into coin cells using a coin cell process and then tested. The fabrication method of the coin cell is as follows: The negative electrode materials prepared in Examples 1-4 and the comparative example were used as negative electrode active materials. They were mixed with vinylidene fluoride (PVDF) (dissolved in N-methylpyrrolidone) and conductive carbon black in a mass ratio of 90:5:5. The mixture was coated into an electrode film and dried in a vacuum drying oven at 120°C for 12 hours. After rolling and punching, the negative electrode sheet was obtained. PP film was used as the coin cell separator and lithium metal sheet was used as the counter electrode. The obtained negative electrode sheet was assembled into a 2430 button cell in a glove box and tested at a test voltage of (0-3) V and a current of 0.05 C. The test results are shown in Table 1.

[0052] The negative electrode materials prepared in Examples 5-6 above were used as negative electrode active materials and mixed evenly with vinylidene fluoride (PVDF) (dissolved in N-methylpyrrolidone) and conductive carbon black in a mass ratio of 90:5:5. The mixture was coated into an electrode film and dried in a vacuum drying oven at 120°C for 12 hours. After rolling and punching, the negative electrode sheet was obtained. Using PP film as the coin cell separator and sodium metal sheet as the counter electrode, the obtained negative electrode sheet was assembled into a 2430 button cell in a glove box. The test was conducted at a test voltage of (0-3) V and a current of 0.05 C. The test results are shown in Table 1. Table 1 As shown in Table 1, porous carbon anode materials containing pre-lithiated / pre-sodium salts and produced through subcritical water reaction exhibit high specific surface area and excellent electrochemical performance.

[0053] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a porous carbon anode material, characterized in that, The process includes the following steps: mixing starch with a template pore-forming agent and reacting it under subcritical water conditions; ultrasonically cleaning the solid mixture after the reaction in deionized water for 2-6 hours to remove excess template pore-forming agent; the remaining template pore-forming agent remains in the pore structure of the porous carbon and participates in the pre-lithiation / pre-sodiumization of the subsequent charge and discharge process to obtain a porous carbon anode material. The subcritical water conditions are in the temperature range of 180-250℃ and the pressure range of 10-30MPa. The template pore-forming agent is lithium chloride or sodium chloride; The mass ratio of the starch to the template pore-forming agent is 1:(4-6).

2. The method for preparing the porous carbon anode material as described in claim 1, characterized in that, The starch mentioned is starch that has undergone drying treatment.

3. The method for preparing the porous carbon anode material as described in claim 1, characterized in that, The starch is selected from at least one of cereal starch, potato starch, and legume starch.

4. A porous carbon anode material, characterized in that, The porous carbon anode material is prepared by the method described in any one of claims 1-3.

5. A secondary battery, characterized in that, Including the porous carbon anode material as described in claim 4.

6. The secondary battery as described in claim 5, characterized in that, The secondary battery is a lithium-ion battery or a sodium-ion battery.

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