Biomass-based hard carbon negative electrode material, preparation method thereof and sodium ion battery

Abstract

The application relates to the technical field of sodium ion batteries, in particular to a biomass-based hard carbon negative electrode material, a preparation method thereof and a sodium ion battery, wherein the preparation method comprises the following steps: biomass raw materials are mixed with inorganic acid to obtain mixed raw materials; the mixed raw materials are subjected to crosslinking treatment under the condition of an inert gas atmosphere and 600-800 DEG C to obtain crosslinked raw materials; and after the crosslinked raw materials are washed to be neutral, high-temperature carbonization treatment is carried out under the condition of an inert gas atmosphere and 1000-1600 DEG C to obtain the biomass-based hard carbon negative electrode material. Biomass is used as a carbon source in the application, and compared with resin and other carbon sources, the carbon source has the advantages of low cost; the preparation process is simple and easy to scale up; the acid and the biomass are uniformly mixed, rich pore structures are generated in the low-temperature crosslinking process, and the pore structures are converted into closed pore structures in the high-temperature carbonization process, so that efficient storage of sodium ions is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sodium ion batteries, and particularly relates to a biomass-based hard carbon negative electrode material, a preparation method thereof and a sodium ion battery. BACKGROUND

[0002] The rapid development of electronic products, high-efficiency electric vehicles and other technologies requires advanced energy storage systems with low cost, high energy density and long cycle life. Lithium ion batteries (LIBs) dominate the energy storage field due to their high energy density and good cycle stability. However, the limited supply of lithium and uneven distribution of resources are the main limiting factors for their application in large-scale grid storage. In contrast, sodium ion batteries (SIBs) with chemical properties similar to LIBs are considered a promising energy storage option due to the low cost and wide availability of sodium resources. The research progress of electrode materials undoubtedly plays a crucial role in the commercialization of SIBs.

[0003] The design and development of high-performance carbon-based materials are key to the commercialization of future SIBs. The performance of carbon-based negative electrode materials is closely related to the precursor. Biomass is considered a promising precursor for functional carbon materials due to its abundant reserves and low cost. However, the sodium storage capacity of carbon-based materials obtained by direct carbonization of biomass is not high enough to limit its application in sodium ion batteries. SUMMARY

[0004] To solve the problem of low sodium storage capacity of biomass-based carbon materials in the prior art, the present application provides a preparation method of a biomass-based hard carbon negative electrode material, which realizes low-temperature cross-linking pore formation by inorganic acid, and then converts the open pores into closed pores through high-temperature treatment, thereby realizing the storage of sodium clusters in the closed pores, greatly improving the sodium storage capacity, and solving the problem of low sodium storage capacity of biomass-based carbon materials in the prior art.

[0005] The technical solution adopted by the present application to solve the technical problems is:

[0006] A preparation method of a biomass-based hard carbon negative electrode material, comprising the following steps:

[0007] S1: mixing biomass raw materials with inorganic acid to obtain mixed raw materials;

[0008] S2: cross-linking treatment of the mixed raw materials under the condition of an inert gas atmosphere and 600-800 DEG C to obtain cross-linked raw materials;

[0009] S3: washing the cross-linked raw materials to neutral, and then high-temperature carbonization treatment under an inert gas atmosphere at 1000-1600 DEG C to obtain a biomass-based hard carbon negative electrode material.

[0010] Optionally, the biomass-based raw material is selected from at least one of cellulose, lignin, humic acid.

[0011] Optionally, the biomass-based raw material has a particle size of 20-200 mesh.

[0012] Optionally, the inorganic acid is selected from at least one of hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, and hydrofluoric acid.

[0013] Optionally, the inorganic acid is an inorganic acid solution, and the concentration of the inorganic acid in the inorganic acid solution is 1-15 mol / L. -1 .

[0014] Optionally, the mass ratio of the biomass raw material to the inorganic acid is 1: (0.3-0.9).

[0015] Optionally, the heating rate during the cross-linking process of step S2 is 0.5-5 ℃ / min. -1 .

[0016] Optionally, the heating rate during the high-temperature carbonization process of step S3 is 0.5-5 ℃ / min. -1 .

[0017] Another object of the present application is to provide a biomass-based hard carbon negative electrode material prepared by the preparation method of the biomass-based hard carbon negative electrode material as described above.

[0018] Still another object of the present application is to provide a sodium ion battery comprising the biomass-based hard carbon negative electrode material as described above.

[0019] The present application has the following advantages:

[0020] The preparation method of the biomass-based hard carbon negative electrode material provided by the present application uses biomass as a carbon source, which has a low-cost advantage compared with resin and other carbon sources. The preparation process is simple and easy to scale up. The acid and biomass are uniformly mixed, so that abundant pore structures are generated during the low-temperature cross-linking process, and the pore structures are converted into closed pore structures during the high-temperature carbonization process, thereby realizing efficient storage of sodium ions. BRIEF DESCRIPTION OF DRAWINGS

[0021] The present application will be further described below in conjunction with the drawings and examples.

[0022] Figure 1 is an SEM image of the biomass-based hard carbon negative electrode material prepared in Example 1 of the present application;

[0023] Figure 2 is an XRD image of the biomass-based hard carbon negative electrode material prepared in Example 1 of the present application;

[0024] Figure 3 is a Raman diagram of the biomass-based hard carbon negative material prepared in Embodiment 1 of the present application;

[0025] Figure 4 is a pore size distribution diagram of the biomass-based hard carbon negative material prepared in Embodiment 1 of the present application;

[0026] Figure 5 is a charge-discharge curve diagram of the biomass-based hard carbon negative material prepared in Embodiment 1 of the present application as a negative electrode of a sodium ion battery. DETAILED DESCRIPTION

[0027] The present application will now be further described in detail. The embodiments described below are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application, and all other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative labor fall within the scope of protection of the present application.

[0028] Although direct carbonization of biomass can obtain carbon materials with large interlayer spacing and rich pore structure, the pores are mostly open pores, which is not conducive to sodium storage and is easy to cause low initial efficiency.

[0029] To solve the problem of low sodium storage capacity of biomass-based carbon materials in the prior art, the present application provides a preparation method of a biomass-based hard carbon negative material, which comprises the following steps:

[0030] S1: mixing biomass raw materials with inorganic acid to obtain mixed raw materials;

[0031] Preferably, the biomass raw materials are mixed with the inorganic acid and stirred, and then the mixed raw materials are obtained by drying, and the mixing time is preferably 1-8 h; the drying process is: heat preservation at 100-180℃ for 12-48 h;

[0032] S2: crosslinking treatment of the mixed raw materials under the condition of inert gas atmosphere and 600-800℃, and the heat preservation time during the crosslinking treatment is preferably 1-4 h to obtain crosslinked raw materials; preferably, the inert gas is nitrogen or argon;

[0033] In this step, the biomass material is crosslinked with the inorganic acid to produce rich pore structure; specifically, in this step, the inorganic acid can promote or catalyze the hydrolysis, dehydration and aromatization reactions of the biomass raw materials, crosslink with the biomass polymer, and have the function of pore formation; by introducing the inorganic acid, the biomass can be crosslinked at a lower temperature, and has a higher activation efficiency, thereby producing a large number of pores;

[0034] S3: after the cross-linked raw material is washed to neutral, high-temperature carbonization treatment is carried out at 1000-1600 DEG C under an inert gas atmosphere, preferably, the holding time during the carbonization treatment is 1-4 h, and the biomass-based hard carbon negative electrode material is obtained; preferably, the inert gas is nitrogen or argon;

[0035] Preferably, the cross-linked raw material is repeatedly washed to neutral with deionized water in the step, and high-temperature carbonization treatment is carried out after drying treatment, and further preferably, the specific process of the water washing treatment is multiple washing, centrifugation and washing until the solution is close to neutral; the drying treatment process is: holding at a temperature of 60-90 DEG C for 12-48 h;

[0036] In the step, the pore structure generated in the cross-linking treatment process is converted into a closed pore structure through high-temperature carbonization, thereby helping to achieve efficient storage of sodium ions.

[0037] The preparation method of the biomass-based hard carbon negative electrode material provided by the application uses biomass as a carbon source, and has a low-cost advantage compared with a carbon source such as resin; and the preparation process is simple and easy to scale up; the acid and the biomass are uniformly mixed in the application, so that abundant pore structures are generated in the low-temperature cross-linking process, and the pore structures are converted into closed pore structures in the high-temperature carbonization process, thereby achieving efficient storage of sodium ions.

[0038] To ensure the sodium storage capacity, the biomass-based raw material is preferably at least one selected from cellulose, lignin, humic acid and crop waste.

[0039] To ensure the cross-linking reaction effect, the biomass is preferably sequentially crushed, ball milled and sieved to obtain fine powder as the biomass raw material; and further preferably, the particle size of the biomass-based raw material is 20-200 mesh.

[0040] The inorganic acid is preferably at least one selected from hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid and hydrofluoric acid; further, the inorganic acid is an inorganic acid solution; and preferably, the concentration of the inorganic acid in the inorganic acid solution is 1-15 mol / L. -1 .

[0041] To ensure the cross-linking effect, the mass ratio of the biomass raw material to the inorganic acid in step S1 is 1:(0.3-0.9), that is, the mass ratio of the biomass raw material to the inorganic acid solution in step S1 is 1:(0.3-0.9).

[0042] The temperature rising process in steps S2 and S3 is preferably programmed temperature rising, and the temperature rising rate during the cross-linking treatment in step S2 and the high-temperature carbonization treatment in step S3 is preferably 0.5-5 DEG C / min. -1 .

[0043] In conclusion, the application provides a method for constructing a closed pore structure of a biomass sodium storage negative electrode.

[0044] The core objective of the application is to solve the problems existing in the biomass sodium storage negative electrode material technology, and a new preparation process for constructing a closed pore structure of a biomass sodium storage negative electrode is proposed. This method creates pores through cross-linking technology and converts open pores into closed pores through high-temperature treatment, thereby realizing the storage of sodium clusters in the closed pores and greatly improving the sodium storage capacity. Constructing a closed pore structure in carbon materials can not only significantly improve the sodium storage capacity, but also improve the initial coulombic efficiency through desolvation. The biomass carbon material obtained by the process has higher sodium storage specific capacity and initial coulombic efficiency, and the process is simple, mild and controllable, which provides strong support for industrialization promotion and application.

[0045] Another objective of the application is to provide a biomass-based hard carbon negative electrode material prepared by the preparation method of the biomass-based hard carbon negative electrode material.

[0046] The biomass-based hard carbon negative electrode material provided by the application uses biomass as a carbon source in the preparation process, which has a low-cost advantage compared with resin and other carbon sources. The preparation process is simple and easy to scale up. The acid and biomass are uniformly mixed in the application, which generates a rich pore structure during the low-temperature cross-linking process and converts it into a closed pore structure during the high-temperature carbonization process, thereby realizing efficient storage of sodium ions.

[0047] Another objective of the application is to provide a sodium ion battery comprising the biomass-based hard carbon negative electrode material.

[0048] The sodium ion battery provided by the application uses a biomass-based hard carbon negative electrode material, which uses biomass as a carbon source in the preparation process, which has a low-cost advantage compared with resin and other carbon sources. The preparation process is simple and easy to scale up. The acid and biomass are uniformly mixed in the application, which generates a rich pore structure during the low-temperature cross-linking process and converts it into a closed pore structure during the high-temperature carbonization process, thereby realizing efficient storage of sodium ions.

[0049] In order to make the above-mentioned objectives, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below with reference to the accompanying drawings.

[0050] Example 1

[0051] This embodiment provides a method for preparing a biomass-based hard carbon anode material, including the following steps:

[0052] S1: Biomass lignin is sequentially crushed, ball-milled, and sieved to obtain a fine powder with a particle size of 200 mesh, thus obtaining biomass raw material; the biomass raw material is mixed with phosphoric acid at a mass ratio of 1:0.75, stirred for 8 hours, and dried at 150℃ for 12 hours to obtain a mixed raw material; the concentration of phosphoric acid is 14.7 mol L. -1 ;

[0053] S2: The mixed raw materials are heated at 5°C for 5 min under a high-purity nitrogen atmosphere. -1 The temperature was increased to 600℃ at a heating rate and held for 2 hours to obtain the cross-linked raw material;

[0054] S3: After repeated washing, centrifugation, and washing until neutral, the cross-linked raw material is dried at 80℃ for 2 hours, and then dried at 5℃ for 1 minute under a high-purity argon atmosphere. -1 The temperature was increased to 1400℃ at a heating rate and held for 3 hours for high-temperature carbonization treatment to obtain biomass-based hard carbon anode material.

[0055] The biomass-based hard carbon anode material was tested, and among the results... Figure 1 The image shows the SEM image of the biomass-based hard carbon anode material. The SEM image shows that the carbon material is in the form of irregular particles. Figure 2 The XRD pattern of this biomass-based hard carbon anode material; Figure 3 The Raman plot of this biomass-based hard carbon anode material is shown, with an ID / IG value of 0.929. Figure 4 The image shows the pore size distribution of this biomass-based hard carbon anode material, with a pore volume of 0.18 m³. 3 g -1 .

[0056] Example 2

[0057] This embodiment provides a method for preparing a biomass-based hard carbon anode material, including the following steps:

[0058] S1: Biomass lignin is sequentially crushed, ball-milled, and sieved to obtain a fine powder with a particle size of 200 mesh, thus obtaining biomass raw material; the biomass raw material is mixed with phosphoric acid at a mass ratio of 1:0.3, stirred for 4 hours, and dried at 100℃ for 24 hours to obtain a mixed raw material; the concentration of phosphoric acid is 14.7 mol L. -1 ;

[0059] S2: The mixed raw materials are heated at 0.5℃ for 1 minute under a high-purity nitrogen atmosphere. -1 The temperature was increased to 600℃ at a heating rate and held for 2 hours to obtain the cross-linked raw material;

[0060] S3: After repeated washing, centrifugation, and washing until neutral, the cross-linked raw material is dried at 80℃ for 2 hours, and then dried at 0.5℃ for 1 minute under a high-purity argon atmosphere. -1 The temperature was increased to 1400℃ at a heating rate and held for 3 hours for high-temperature carbonization treatment to obtain biomass-based hard carbon anode material.

[0061] Example 3

[0062] This embodiment provides a method for preparing a biomass-based hard carbon anode material, including the following steps:

[0063] S1: Biomass lignin is sequentially crushed, ball-milled, and sieved to obtain a fine powder with a particle size of 200 mesh, thus obtaining biomass raw material; the biomass raw material is mixed with phosphoric acid at a mass ratio of 1:0.9, stirred for 8 hours, and dried at 150℃ for 12 hours to obtain a mixed raw material; the concentration of phosphoric acid is 14.7 mol L. -1 ;

[0064] S2: The mixed raw materials are heated at 2.5℃ for 1 minute under a high-purity nitrogen atmosphere. -1 The temperature was increased to 600℃ at a heating rate and held for 2 hours to obtain the cross-linked raw material;

[0065] S3: After repeated washing, centrifugation, and washing until neutral, the cross-linked raw material is dried at 80℃ for 2 hours, and then dried at 2.5℃ for 1 minute under a high-purity argon atmosphere. -1 The temperature was increased to 1400℃ at a heating rate and held for 3 hours for high-temperature carbonization treatment to obtain biomass-based hard carbon anode material.

[0066] Example 4

[0067] The difference between this embodiment and Embodiment 1 is that step S2 is:

[0068] Under a high-purity nitrogen atmosphere, at 5℃ min -1 The temperature was increased to 800℃ at a certain rate and held for 1 hour to obtain the cross-linked raw material.

[0069] Example 5

[0070] The difference between this embodiment and Embodiment 1 is that step S3 is:

[0071] After repeated washing, centrifugation, and washing until neutral, the cross-linked raw material was dried at 80℃ for 2 hours and then subjected to high-purity argon atmosphere at 5℃ for 1 minute. -1 The temperature was increased to 1600℃ at a heating rate and held for 1 hour for high-temperature carbonization treatment to obtain biomass-based hard carbon anode material.

[0072] In this invention, each comparative example is used to compare with Example 1.

[0073] Comparative Example 1

[0074] This comparative example provides a method for preparing a biomass-based hard carbon anode material, including the following steps:

[0075] S1: The biomass lignin is crushed, ball-milled, and sieved in sequence to obtain fine powder with a particle size of 200 mesh. The powder is then dried at 150℃ for 12 hours to obtain biomass raw material.

[0076] S2: The biomass feedstock is heated at 5°C for 5 minutes under a high-purity nitrogen atmosphere. -1 The temperature was increased to 600℃ at a heating rate and held for 2 hours to obtain the processed raw material.

[0077] S3: After washing and centrifuging the processed raw material multiple times until neutral, dry it at 80℃ for 2 hours, and then dry it at 5℃ for 5 minutes under a high-purity argon atmosphere. -1 The temperature was increased to 1400℃ at a heating rate and held for 3 hours for high-temperature carbonization treatment to obtain biomass-based hard carbon anode material.

[0078] Comparative Example 2

[0079] This comparative example provides a method for preparing a biomass-based hard carbon anode material, including the following steps:

[0080] S1: Biomass lignin is sequentially crushed, ball-milled, and sieved to obtain a fine powder with a particle size of 200 mesh, thus obtaining biomass raw material; the biomass raw material is mixed with phosphoric acid at a mass ratio of 1:0.75, stirred for 8 hours, and dried at 150℃ for 12 hours to obtain a mixed raw material; the concentration of phosphoric acid is 14.7 mol L. -1 ;

[0081] S2: The mixed raw materials are heated at 5°C for 5 min under a high-purity argon atmosphere. -1 The temperature was increased to 1400℃ at a heating rate and held for 3 hours for high-temperature carbonization treatment to obtain biomass-based hard carbon anode material.

[0082] Comparative Example 3

[0083] This comparative example provides a method for preparing a biomass-based hard carbon anode material, including the following steps:

[0084] S1: Biomass lignin is sequentially crushed, ball-milled, and sieved to obtain a fine powder with a particle size of 200 mesh, thus obtaining biomass raw material; the biomass raw material is mixed with phosphoric acid at a mass ratio of 1:0.75, stirred for 8 hours, and dried at 150℃ for 12 hours to obtain a mixed raw material; the concentration of phosphoric acid is 14.7 mol L. -1 ;

[0085] S2: The mixed raw materials are heated at 5°C for 5 min under a high-purity nitrogen atmosphere. -1 The temperature was increased to 300℃ at a heating rate and held for 2 hours to obtain the cross-linked raw material;

[0086] S3: After repeated washing, centrifugation, and washing until neutral, the cross-linked raw material is dried at 80℃ for 2 hours, and then dried at 5℃ for 1 minute under a high-purity argon atmosphere. -1 The temperature was increased to 1400℃ at a heating rate and held for 3 hours for high-temperature carbonization treatment to obtain biomass-based hard carbon anode material.

[0087] Comparative Example 4

[0088] This comparative example provides a method for preparing a biomass-based hard carbon anode material, including the following steps:

[0089] S1: The biomass lignin is crushed, ball-milled, and sieved sequentially to obtain a fine powder with a particle size of 200 mesh, thus obtaining the biomass raw material; the biomass raw material is mixed with oxalic acid at a mass ratio of 1:0.75, stirred for 8 hours, and dried at 150℃ for 12 hours to obtain the mixed raw material;

[0090] S2: The mixed raw materials are heated at 5°C for 5 min under a high-purity nitrogen atmosphere. -1 The temperature was increased to 600℃ at a heating rate and held for 2 hours to obtain the cross-linked raw material;

[0091] S3: After repeated washing, centrifugation, and washing until neutral, the cross-linked raw material is dried at 80℃ for 2 hours, and then dried at 5℃ for 1 minute under a high-purity argon atmosphere. -1 The temperature was increased to 1400℃ at a heating rate and held for 3 hours for high-temperature carbonization treatment to obtain biomass-based hard carbon anode material.

[0092] The sodium storage performance of the hard carbon anode materials prepared in the various embodiments and comparative examples of this invention was evaluated using coin cells. The mass ratio of the electrode slurry was 90:5:5 for active material (hard carbon material): conductive agent (carbon black): binder (polyvinylidene fluoride). An appropriate amount of N-methylpyrrolidone was added to prepare the slurry, which was then coated onto copper foil to a thickness of 100 μm. After drying and pressing, the slurry was formed into an electrode sheet, using metallic sodium as the counter electrode and 1 mol L... -1A 2032 coin cell was assembled using a NaPF6 DEC+EC (volume ratio 1:1) solution as the electrolyte and glass fiber GF / C as the separator. The cell was tested at 0.02, 0.04, 0.1, 0.2, 0.4, and 1 A g. -1 Its charge-discharge performance was tested at a current density, and the test results are shown in Table 1; among which... Figure 5 The image shows the charge-discharge curves of the hard carbon anode material prepared in Example 1 when used as the anode in a sodium-ion battery, with a reversible capacity of 446.6 mAh g⁻¹. -1 .

[0093] Table 1

[0094]

[0095] As can be seen from the table above, the hard carbon anode materials prepared in the various embodiments of the present invention have high sodium storage specific capacity and first coulombic efficiency.

[0096] The difference between Comparative Example 1 and Example 1 is that no inorganic acid was added. Because there is no activation and cross-linking effect of inorganic acid, only a small amount or no closed pores are generated during the carbonization process, and the sodium storage capacity and first efficiency of the prepared hard carbon anode material are relatively low.

[0097] The difference between Comparative Example 2 and Example 1 is that the mixed raw materials were not cross-linked at 600-800℃. Because inorganic acids and biomass can only undergo activation cross-linking in a specific temperature range, direct high-temperature carbonization, although inorganic acids are present in the raw materials, cannot effectively activate cross-linking, and the prepared hard carbon anode material does not produce closed pores, resulting in lower capacity and first-time efficiency.

[0098] The difference between Comparative Example 3 and Example 1 is that the temperature of the crosslinking treatment in step S2 is changed to 300°C. Because the activation effect of inorganic acid on crosslinking is limited at this temperature, the prepared hard carbon anode material does not produce closed pores, resulting in low capacity and low first-efficiency.

[0099] The difference between Comparative Example 4 and Example 1 is that oxalic acid is used instead of phosphoric acid. Under the reaction conditions provided by this invention, the activating and pore-forming effect of oxalic acid is very limited, resulting in a smaller number of closed pores in the prepared hard carbon anode material, which leads to lower capacity and first-time efficiency.

[0100] 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 biomass-based hard carbon anode material, characterized in that, Includes the following steps: S1: Mix biomass raw materials with inorganic acids to obtain mixed raw materials; S2: The mixed raw materials are subjected to cross-linking treatment under an inert gas atmosphere and at 600°C. The inorganic acid catalyzes the hydrolysis, dehydration, and aromatization of the biomass raw materials and cross-links with the biomass raw materials to obtain the cross-linked raw materials. S3: After washing the cross-linked raw material to neutrality, it is subjected to high-temperature carbonization treatment at 1000~1400℃ under an inert gas atmosphere to obtain biomass-based hard carbon anode material. The mass ratio of the biomass raw material to the inorganic acid is 1:0.75; The biomass-based raw material is selected from at least one of cellulose, lignin, and humic acid; The inorganic acid is phosphoric acid.

2. The method for preparing the biomass-based hard carbon anode material as described in claim 1, characterized in that, The particle size of the biomass-based raw material is 20-200 mesh.

3. The method for preparing the biomass-based hard carbon anode material as described in claim 1, characterized in that, The inorganic acid is an inorganic acid solution; the concentration of the inorganic acid in the inorganic acid solution is 1~15 mol / L. -1 .

4. The method for preparing the biomass-based hard carbon anode material as described in claim 1, characterized in that, During the crosslinking process in step S2, the heating rate is 0.5~5℃ min. -1 .

5. The method for preparing the biomass-based hard carbon anode material as described in claim 1, characterized in that, In step S3, the heating rate during the high-temperature carbonization process is 0.5~5℃ min. -1 .

6. A biomass-based hard carbon anode material, characterized in that, The biomass-based hard carbon anode material is prepared using the preparation method described in any one of claims 1-5.

7. A sodium-ion battery, characterized in that, Including the biomass-based hard carbon anode material as described in claim 6.

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