High-performance biomass-based hard carbon material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of preparation of sodium ion battery electrode materials, and particularly relates to a high-performance biomass-based hard carbon negative electrode material as well as a preparation method and application thereof. The particle matrix in the prepared hard carbon negative electrode material has more carbonyl groups, when the biomass-based hard carbon material is used for the negative electrode of the sodium-ion battery, a solid electrolyte interface film can be pre-generated in the standing process, and the first-circle efficiency and the rate capability of the sodium-ion battery are improved. The method provided by the invention has the advantages of cheap raw materials, simple and safe preparation process, and high commercial value. When the prepared hard carbon material is used as a sodium ion battery negative electrode material, the raw material cost is low, pollution is avoided, the first circle efficiency and the rate capability of the obtained negative electrode material are improved, and the hard carbon material can be used for a high-performance sodium ion battery negative electrode.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery electrode material preparation technology, specifically relating to a high-performance biomass-based hard carbon material, its preparation method, and its application. Background Technology

[0002] Since the Industrial Revolution, fossil fuels, as the cornerstone of the global energy system, have greatly propelled the modernization of human civilization. However, the energy security and ecological environmental problems accumulated from their long-term large-scale combustion have become increasingly prominent, directly threatening sustainable development. Against this backdrop, developing clean, low-carbon, safe, and efficient energy storage technologies, primarily based on renewable energy, has become a global consensus and an urgent task. Lithium-ion batteries, with their short construction cycle, flexible deployment, high energy density, and excellent energy conversion efficiency, have been widely used in electric vehicles, portable electronic devices, and smart grids. However, the explosive growth of the lithium-ion battery industry has also led to a huge global demand for lithium resources. The scarcity and geographical concentration of lithium resources severely restrict the widespread adoption and application of lithium-ion batteries in low-cost, large-scale energy storage scenarios.

[0003] Sodium and lithium are elements in the same group, and sodium possesses similar electrochemical properties to lithium. Furthermore, sodium is abundant and inexpensive, making sodium-ion batteries (SIBs) the next generation of commercially viable secondary batteries after lithium-ion batteries (LIBs). Based on the reversible insertion / extraction reaction of sodium ions, the working principle and manufacturing process of sodium-ion batteries are highly compatible with the mature lithium-ion battery industry. Therefore, developing sodium-ion battery technology is of paramount strategic importance for ensuring national energy security, optimizing the energy structure, and achieving the ambitious goal of "dual carbon" energy conservation.

[0004] The overall performance of sodium-ion batteries largely depends on their core electrode materials, especially the anode material. Graphite anodes, widely used in lithium-ion batteries, have a very low sodium-ion storage capacity in conventional electrolytes due to thermodynamic reasons, making them unsuitable for direct use. Currently, anode material systems for sodium-ion batteries mainly revolve around hard carbon materials, transition metal oxides / sulfides, and alloy materials. Among these, hard carbon materials (an amorphous carbon that is difficult to graphitize) are considered the most promising anode material for sodium batteries due to their unique structure and comprehensive advantages.

[0005] Currently, biomass raw materials are excellent for preparing hard carbon due to their wide availability, low cost, and high content of cellulose, hemicellulose, and lignin. Therefore, biomass materials such as coconut shells, rice straw, pollen, and bamboo are mainly used as precursors to prepare hard carbon anode materials for sodium-ion batteries; specifically, biomass is mostly used as the carbon source. However, the low first-cycle efficiency and poor rate performance of biomass-based hard carbon limit its application in commercial sodium battery anodes.

[0006] In related studies, although researchers have increased the disorder of hard carbon by improving heteroatom doping or physical etching to enhance its specific capacity and rate performance, this often leads to an increase in irreversible defects on the hard carbon surface. This results in significant irreversible capacity loss during the first charge-discharge cycle, leading to low initial efficiency and hindering the commercialization of this type of hard carbon. Alternatively, some researchers have reduced irreversible defects on the hard carbon surface by coating it with soft carbon, thereby improving initial efficiency; however, the problem of low rate performance of hard carbon remains unresolved.

[0007] Therefore, it is urgent to develop new hard carbon anode materials with high first-cycle efficiency, high rate capability, high safety, and suitability for metal-ion batteries, especially sodium-ion batteries. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing technologies by proposing a high-performance biomass-based hard carbon material, its preparation method, and its applications. The hard carbon material prepared by this invention has a large number of carbonyl groups in its particle matrix. When this biomass hard carbon material is used as the negative electrode of a sodium-ion battery, the carbonyl groups can induce electrolyte decomposition to pre-form a uniform and stable solid electrolyte interface, thereby improving the diffusion kinetics of metal ions in the hard carbon and reducing irreversible capacity loss, thus improving the rate performance of the metal-ion battery and increasing the first-cycle efficiency.

[0009] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0010] As a first aspect of the invention, the present invention provides a method for preparing a high-performance biomass-based hard carbon anode material, comprising the following steps:

[0011] 1) Purification of biomass raw materials: Take a certain mass of biomass raw materials, add them to sulfuric acid solution and stir to dissolve for 10-30 minutes, then react at a high temperature of 180-240℃ for 1-12 hours. After the reaction is completed, filter and dry to obtain purified material.

[0012] 2) Preparation of precursor: The purified material obtained in step 1) is mixed with 2,6-pyridinedicarboxylic acid and then ground for 30-40 minutes to obtain the precursor;

[0013] 3) Precursor carbonization: The precursor in step 2) is subjected to high-temperature carbonization treatment to obtain hard carbon material;

[0014] 4) Secondary grinding and pulverization: The hard carbon material from step 3) is subjected to secondary grinding and pulverization to obtain the final product.

[0015] Preferably, in step 1), the biomass-based raw material is a raw material rich in cellulose, hemicellulose and lignin; the concentration of the sulfuric acid solution is 0.1-2 mol; and the ratio of biomass raw material to sulfuric acid solution is (1-10) g: 100 mL.

[0016] More preferably, the biomass raw material is bamboo powder or coffee grounds.

[0017] Preferably, in step 2), the mass ratio of the 2,6-pyridinedicarboxylic acid to the purified material in step 1) is (1-2):10.

[0018] Preferably, in step 4), the carbonization process is specifically performed as follows: under a protective atmosphere, at 2–5 °C for [time range missing] minutes. –1 The temperature is rapidly increased to 700–800℃ and held for 20–30 minutes for pre-carbonization; then further carbonization is carried out at 1–2℃ / min. –1 The temperature is rapidly increased to 1100℃~1500℃, and carbonization is carried out under a protective atmosphere for 1~2 hours, followed by a rate of 1~2℃ / min. –1 Cool down at a rate of 700–800°C, then at a rate of 2–5°C / min. –1 The temperature is gradually reduced to 400-500℃, and then allowed to cool naturally to room temperature.

[0019] Further preferably, the protective atmosphere for the carbonization process is an inert gas, preferably nitrogen or argon.

[0020] Preferably, in step 4), the specific operation of the secondary grinding post-processing is as follows: the carbonized hard carbon material is first manually ground for 20 to 30 minutes, and then placed in a ball mill and ball-milled at a speed of 800 to 1000 r / min for 30 to 60 minutes to crush it into smaller particles.

[0021] As a second aspect of the invention, the invention also provides a high-performance biomass-based hard carbon material prepared by the above method. This hard carbon material has extremely high first-cycle efficiency and charge-discharge performance, and can be used as a negative electrode material in metal-ion batteries such as lithium-ion batteries, sodium-ion batteries, and potassium-ion batteries.

[0022] As another aspect of the invention, the invention also provides the application of the above-mentioned high-performance biomass-based hard carbon material in the preparation of composite electrode slurry or metal-ion batteries, wherein the metal ion is a lithium-ion battery, a sodium-ion battery, or a potassium-ion battery.

[0023] Furthermore, a method for preparing composite electrode slurry using the aforementioned high-performance biomass-based hard carbon material is disclosed, including the following steps:

[0024] (1) Weigh a certain amount of active material, conductive agent and binder and mix them to obtain a mixed powder; the active material is the above-mentioned high-performance biomass-based hard carbon material;

[0025] (2) Add 1 to 1.5 times the mass of the dispersing solvent to the mixed powder in step (1), first ultrasonically disperse it at a power of 80 to 100W for 8 to 12 minutes, and then stir it at a speed of 300 to 400 r / min for 8 to 12 hours to make the active material and conductive agent dispersed evenly, and obtain the composite electrode slurry.

[0026] Preferably, in step (1), the conductive agent is carbon black (Super-P); the binder is PVDF; the dispersing solvent is selected from deionized water, ethanol and NMP; in step (2), the weight ratio of active material, conductive agent and binder in the composite electrode slurry is (6-8):1:(1-2).

[0027] The present invention further discloses a method for preparing metal-ion batteries using the aforementioned high-performance biomass-based hard carbon material, specifically including the following steps:

[0028] a) Preparation of electrode sheet: Take the composite electrode slurry prepared by the above high-performance biomass-based hard carbon material, coat it on copper foil, dry it at 60-80℃ for 8-12h, and then use a punch to make it into a button electrode sheet with a diameter of 12mm.

[0029] b) Button cell assembly: Using a metal sheet as the counter electrode, assemble into a button cell and let it stand for 24 to 144 hours.

[0030] Preferably, in step b), the metal sheet is a sodium metal sheet, the battery model is a CR2032 coin cell, the separator used in the battery is a Whatman GF / D separator, and the main component of the electrolyte used in the battery is sodium salt (sodium hexafluorophosphate); preferably, the electrolyte is 1M NaPF6 in DEGDME.

[0031] Compared with the prior art, the advantages of the present invention are:

[0032] 1. Existing hard carbon anode materials suffer from drawbacks such as low initial-cycle efficiency, poor rate performance, low rapid sodium insertion / extraction capability, and poor charging performance. The hard carbon anode material prepared in this invention has a particle matrix with numerous carbonyl groups, exhibiting high initial-cycle efficiency and good rate performance. When this biomass hard carbon material is used as the anode in sodium-ion batteries, the carbonyl groups can induce electrolyte decomposition to pre-form a uniform and stable solid electrolyte interface, thereby improving the diffusion kinetics of sodium ions in the hard carbon and reducing irreversible capacity loss, thus improving the rate performance and initial-cycle efficiency of the sodium-ion battery.

[0033] 2. The method of the present invention uses inexpensive raw materials, has a simple and safe manufacturing process, and has high commercial value.

[0034] 3. The hard carbon anode material prepared by this invention has low raw material cost and no pollution when used as anode material for sodium-ion batteries. The specific capacity and rate performance of the obtained anode material are improved, and it can be used as anode material for high-performance sodium-ion batteries. Attached Figure Description

[0035] Figure 1 This is a flowchart of the preparation method of the high-performance biomass-based hard carbon material described in this invention;

[0036] Figure 2 SEM image of the high-performance biomass-based hard carbon material prepared in Example 1;

[0037] Figure 3 This is a cryo-electron microscopy image of the high-performance biomass-based hard carbon material prepared in Example 1 after standing for 144 hours before cycling;

[0038] Figure 4 To fabricate sodium-ion batteries using the hard carbon anode materials of Application Examples 1 and 3 in 0.1 Ag... –1 Cyclic performance graph;

[0039] Figure 5 To prepare sodium-ion batteries using the hard carbon anode materials of Application Examples 1-3 and Comparative Example 1, the anode material was tested in the range of 0.05–2 Ag. –1 Ratio performance diagram;

[0040] Figure 6 To fabricate sodium-ion batteries using the hard carbon anode materials of Application Examples 1-3 and Comparative Example 1 at 0.05 Ag... –1 The first charge-discharge curve. Detailed Implementation

[0041] The following embodiments, in conjunction with the accompanying drawings, will further illustrate the present invention. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and processes; however, the scope of protection of the present invention is not limited to the following embodiments.

[0042] It should be noted that the experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions, and the raw materials and reagents used are all commercially available products unless otherwise specified.

[0043] In the examples, the specification of 2,6-pyridinedicarboxylic acid was 99% (AR); the manufacturer was Shanghai McLean Biochemical Technology Co., Ltd.

[0044] Example 1

[0045] This embodiment provides a method for preparing high-performance biomass-based hard carbon materials, the flowchart of which is shown below. Figure 1 As shown, the specific steps are as follows:

[0046] 1) Purification of biomass raw materials: Take 10g of bamboo powder and stir it in 100mL of 0.5mol sulfuric acid solution for 10min to obtain a dark and opaque solution. Pour the obtained solution into a reaction vessel and react at 220℃ for 2h. After the reaction is completed, filter the solution and dry it to obtain a brown solid, which is the purified material.

[0047] 2) Preparation of precursor: Take 1g of the purified material obtained in step 1) and mix it with 0.1g of 2,6-pyridinedicarboxylic acid, then grind and pulverize for 30min. The solid obtained is the precursor.

[0048] 3) Precursor carbonization: The ground precursor solid is placed in a high-temperature furnace and heated at 5°C for 1 minute under a protective atmosphere. –1 The temperature is rapidly increased to 800℃ and held for 30 minutes for pre-carbonization; then further heated at 2℃ / min... –1 The temperature was increased to 1300℃ at a rate of [unspecified rate], and carbonization was carried out for 2 hours under a protective atmosphere, followed by [unspecified process] at 2℃ / min. –1 The temperature was reduced to 800℃ at a rate of 5℃ / min. –1 The temperature is gradually reduced to 500°C, and then allowed to cool naturally to room temperature. The resulting product is hard carbon material. The protective atmosphere during the carbonization process is nitrogen.

[0049] 4) Secondary grinding and pulverization (post-grinding treatment of carbonized hard carbon material): The carbonized hard carbon material is first manually ground for about 30 minutes, and then placed in a ball mill and ball-milled at a speed of 1000 r / min for 60 minutes to pulverize the hard carbon in the ball mill into smaller particles, which is the final product.

[0050] Simultaneously, SEM testing was performed on the final product from Example 1, and the results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the product prepared in Example 1 has a particle size distribution of 5 μm to 31 μm (average particle size of 13.5 μm) and a specific surface area of ​​60 m². 2 g –1 The average pore size is 0.8 nm. Cryo-electron microscopy analysis shows that it can form an SEI film with a large area of ​​inorganic matter after standing for 144 hours before cycling. Figure 3 As shown, its specific capacity is ≥320mAh g. –1 The initial efficiency is ≥85%. The cryo-electron microscopy testing method is as follows: coin cells were tested using a Blue Electric electrochemical workstation, and long-cycle testing was performed using 0.1Ag... –1The current density was set at 0.01V-2.5V, and the charge / discharge cutoff voltage was used to conduct a 300-cycle charge / discharge test on the coin cell battery; the rate test was performed using a range of 0.05~2Ag. –1 The current density and charge / discharge cutoff voltage are 0.01V-2.5V. The capacity decay rate of coin cells under high current charge and discharge is tested.

[0051] Example 2

[0052] This embodiment provides a method for preparing high-performance biomass-based hard carbon materials, the specific steps of which are as follows:

[0053] 1) Purification of biomass raw materials: Take 10g of bamboo powder, add it to 100mL of 0.1mol sulfuric acid solution and stir to dissolve for 30min to obtain a dark and opaque solution. Pour the obtained solution into a reaction vessel and react at 180℃ for 12h. After the reaction is completed, filter the solution and dry it to obtain a brown solid, which is the purified material.

[0054] 2) Preparation of precursor: Take 1g of the purified material obtained in step 1) and mix it with 0.2g of 2,6-pyridinedicarboxylic acid, then grind and pulverize for 40min. The solid obtained is the precursor.

[0055] 3) Precursor carbonization: The ground precursor solid is placed in a high-temperature furnace and heated at 2°C for 2 minutes under a protective atmosphere. –1 The temperature is increased to 700℃ at a rate of 1℃ / min, and held for 20 minutes for pre-carbonization treatment; then further carbonization is carried out at a rate of 1℃ / min. –1 The temperature was increased to 1100℃ at a rate of 1 minute, and carbonization was carried out under a protective atmosphere for 1 hour, followed by a rate of 1℃ / min. –1 The temperature was reduced to 700℃ at a rate of 2℃ / min. –1 The temperature is gradually reduced to 400°C, and then allowed to cool naturally to room temperature. The resulting product is hard carbon material. The protective atmosphere during the carbonization process is nitrogen.

[0056] 4) Secondary grinding and pulverization (post-grinding treatment of carbonized hard carbon material): The carbonized hard carbon material is first manually ground for 20 minutes, and then placed in a ball mill and ball-milled at a speed of 800 r / min for 30 minutes to pulverize the hard carbon in the ball mill into smaller particles, which is the final product.

[0057] Example 3

[0058] This embodiment provides a method for preparing high-performance biomass-based hard carbon materials, the specific steps of which are as follows:

[0059] 1) Purification of biomass raw materials: Take 10g of bamboo powder, add it to 100mL of 2mol sulfuric acid solution and stir to dissolve for 10min to obtain a dark and opaque solution. Pour the obtained solution into a reaction vessel and react at 240℃ for 1h. After the reaction is completed, filter the solution and dry it to obtain a brown solid, which is the purified material.

[0060] 2) Preparation of precursor: Take 1g of the purified material obtained in step 1) and mix it with 0.1g of 2,6-pyridinedicarboxylic acid, then grind and pulverize for 35min. The solid obtained is the precursor.

[0061] 3) Precursor carbonization: The ground precursor solid is placed in a high-temperature furnace and heated at 3°C ​​for 3 minutes under a protective atmosphere. –1 The temperature is rapidly increased to 750℃ and held for 25 minutes for pre-carbonization; then further carbonization is carried out at 2℃ / min. –1 The temperature was rapidly increased to 1500℃, and carbonization was carried out for 1.5 hours under a protective atmosphere, followed by a reduction at 1.5℃ per minute. –1 The temperature was reduced to 750°C at a rate of 3°C / min. –1 The temperature is gradually reduced to 450°C, and then allowed to cool naturally to room temperature. The resulting product is hard carbon material. The protective atmosphere during the carbonization process is nitrogen.

[0062] 4) Secondary grinding and pulverization (post-grinding treatment of carbonized hard carbon material): The carbonized hard carbon material is first manually ground for 25 minutes, and then placed in a ball mill and ball-milled at a speed of 900 r / min for 40 minutes to pulverize the hard carbon in the ball mill into smaller particles, which is the final product.

[0063] In other embodiments for preparing the high-performance biomass-based hard carbon material of the present invention, the biomass-based raw material can also be coffee grounds, and can be any raw material rich in cellulose, hemicellulose and lignin.

[0064] Example 4

[0065] This embodiment provides a method for preparing composite electrode slurry using high-performance biomass-based hard carbon materials. The specific steps are as follows:

[0066] (1) Weigh 400mg of the hard carbon material (active substance) of Example 1, 50mg of carbon black (Super-P, conductive agent, Shenzhen Kejing Zhida Technology Co., Ltd., CAS1333-86-4) and 50mg of binder PVDF, and place the three in a container in sequence to obtain a mixed powder;

[0067] (2) Add solvent (NMP) to the mixed powder in step (1). The mass of the solvent is 1.5 times the mass of the mixed powder. Disperse the mixture ultrasonically at 100W for 8 minutes. Then, put polytetrafluoroethylene magnets into the container and stir at 400r / min for 10 hours to disperse the hard carbon material and carbon black (Super-P) evenly, and obtain the composite electrode slurry. The mass ratio of active material, conductive agent and binder is 8:1:1.

[0068] In other embodiments of preparing composite electrode slurry, step (2) satisfies the following: "Add 1 to 1.5 times the mass of the dispersing solvent to the mixed powder in step (1), first ultrasonically disperse at a power of 80 to 100 W for 8 to 12 min, and then stir at a speed of 300 to 400 r / min for 8 to 12 h" and "In the composite electrode slurry, the weight ratio of active material, conductive agent and binder is (6 to 8): 1: (1 to 2)" to achieve the effect of the present invention.

[0069] Application Example 1

[0070] To illustrate the effects of this invention, this application example uses the hard carbon material prepared in Example 1 as the negative electrode material to fabricate a CR2032 coin cell (sodium-ion battery). The specific steps are as follows:

[0071] a) Preparation of electrode sheet: Take the composite electrode slurry prepared in Example 4, coat it evenly on copper foil (current collector), dry it at 80°C for 10 hours, and make a button electrode disc with a diameter of 12 mm using a punch.

[0072] b) Button cell assembly: Using a sodium metal sheet as the counter electrode, the cells are assembled into button cells and left to stand for 24 hours. The cell model is a CR2032 type button cell. The separator type is Whatman GF / D. The main component of the electrolyte used in the cell is sodium salt (sodium hexafluorophosphate). Specifically, the electrolyte is 1M NaPF6 in DEGDME.

[0073] Application Example 2

[0074] The difference between Application Example 2 and Application Example 1 is that in step b), after assembling the button cell, it is left to stand for 72 hours, while everything else is the same as in Application Example 1.

[0075] In other application examples, the effect of the present invention can be achieved by drying at 60-80°C for 8-12 hours in step a).

[0076] Application Example 3

[0077] The difference between Application Example 3 and Application Example 1 is that in step b), after assembling the button cell, it is left to stand for 144 hours, while the rest is the same as in Application Example 1.

[0078] In other application examples, the effect of the present invention can be achieved by drying at 60-80°C for 8-12 hours in step a).

[0079] Comparative Example 1

[0080] The difference between Comparative Example 1 and Application Example 1 is that in step b), after assembling the button cell, it is left to stand for 6 hours, while everything else is the same as in Application Example 1.

[0081] In other application examples, the effect of the present invention can be achieved by drying at 60-80°C for 8-12 hours in step a).

[0082] Comparative Example 2

[0083] The difference between this comparative example and application example 3 is that Kuraray T1 hard carbon is used as the negative electrode material to make a CR2032 type button cell (sodium-ion battery), while all other aspects are the same as application example 3.

[0084] Comparative Example 3

[0085] The difference between this comparative example and application example 3 is that Kuraray T2 hard carbon is used as the negative electrode material to make a CR2032 type button cell (sodium-ion battery), while all other aspects are the same as application example 3.

[0086] Comparative Example 4

[0087] The difference between this comparative example and application example 3 is that Baisige hard carbon is used as the negative electrode material to make a CR2032 type button cell (sodium-ion battery), while all other aspects are the same as application example 3.

[0088] Performance Test 1

[0089] For example cases 1-3, CR2032 coin cells prepared using the hard carbon anode material of Example 1 were tested for battery performance. The test method is as follows: the coin cells were tested using a Blue Electric electrochemical workstation, and the long-cycle test used 0.1Ag. –1 The current density was set at 0.01V-2.5V, and the charge / discharge cutoff voltage was used to conduct a 300-cycle charge / discharge test on the coin cell battery; the rate test was performed using a range of 0.05~2Ag. –1 The capacity decay rate of coin cells under high-current charge and discharge conditions was tested using a current density and a charge / discharge cutoff voltage of 0.01V-2.5V. The test results are shown in Table 1. Figure 4 , Figure 5 and Figure 6 .

[0090] The charge / discharge current for cyclic testing is 0.1Ag. –1 The charge / discharge cutoff voltage is 0.01V-2.5V. The initial capacity and coulombic efficiency of the coin cell were tested, and the cell was subjected to 300 charge / discharge cycles.

[0091] The charge / discharge current for cyclic testing is 0.05–2 Ag. –1 The charge / discharge cutoff voltage is 0.01V-2.5V. The capacity decay rate of the coin cell under high-current charge / discharge conditions was tested.

[0092] Table 1 Sodium storage performance of Application Examples 1-3 and Comparative Examples 1-4

[0093]

[0094] As can be seen from Table 1, compared with Application Examples 1-2 and Comparative Examples 1-4, the sodium-ion battery prepared in Application Example 3 has a higher specific capacity, better capacity retention after 300 cycles, and an increased current density to 2 Ag. –1 The capacity retention rate is high afterward, and the initial coulomb efficiency is also high.

[0095] The preparation method of the high-performance biomass-based hard carbon anode material described in this invention simplifies the preparation process of sodium-ion battery anode materials in the prior art, and significantly improves battery performance. It has good application value and is suitable for industrial promotion and application.

[0096] 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. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present 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 a high-performance biomass-based hard carbon material, characterized by, The method comprises the following steps: 1) purification of the biomass raw material: a certain mass of biomass raw material is first added to a sulfuric acid solution and stirred and dissolved for 10-30 min, and then reacted at a high temperature of 180-240°C for 1-12 h. After the reaction is completed, the purified material is obtained by suction filtration and drying; 2) preparation of the precursor: the purified material obtained in step 1) is mixed with 2,6-pyridine dicarboxylic acid and ground and crushed for 30-40 min to obtain the precursor; 3) carbonization of the precursor: the precursor of step 2) is subjected to high-temperature carbonization treatment to obtain a hard carbon material; 4) secondary grinding and crushing: the hard carbon material of step 3) is subjected to secondary grinding and post-treatment to obtain the final product.

2. The method for preparing high-performance biomass-based hard carbon material as described in claim 1, characterized in that, In step 1), the biomass-based raw material is a raw material rich in cellulose, hemicellulose and lignin, preferably bamboo powder or coffee grounds; the concentration of the sulfuric acid solution is 0.1-2 mol; and the ratio of the amount of biomass raw material to the amount of sulfuric acid solution is (1-10) g: 100 mL.

3. The preparation method of the high-performance biomass-based hard carbon anode material as described in claim 1, characterized in that, In step 2), the mass ratio of 2,6-pyridine dicarboxylic acid to the purified material of step 1) is (1-2):

10.

4. The method for preparing high-performance biomass-based hard carbon material as described in claim 1, characterized in that, In step 3), the specific operation of carbonization is as follows: under a protective atmosphere, at 2-5℃ for min... -1 The temperature is rapidly increased to 700–800℃ and held for 20–30 minutes for pre-carbonization; then further carbonization is carried out at 1–2℃ / min. -1 The temperature is rapidly increased to 1100℃~1500℃, and carbonization is carried out under a protective atmosphere for 1~2 hours, followed by a rate increase of 1~2℃ / min. –1 Cool down at a rate of 700–800°C, then at a rate of 2–5°C / min. –1 The temperature is gradually reduced to 400-500℃, and then allowed to cool naturally to room temperature.

5. The method for preparing high-performance biomass-based hard carbon material as described in claim 1, characterized in that, In step 4), the specific operation of the secondary grinding and post-treatment is as follows: the carbonized hard carbon material is first manually ground for 20-30 min, and then placed in a ball mill for ball milling at a speed of 800-1000 r / min for 30 min-60 min to crush the material into smaller particles.

6. A high-performance biomass-based hard carbon material prepared by the method of any one of claims 1-5.

7. The use of the high-performance biomass-based hard carbon material of claim 6 in the preparation of a composite electrode slurry or a metal ion battery, wherein the metal ion battery is a sodium ion battery or a lithium ion battery or a potassium ion battery.

8. A method of preparing a composite electrode slurry using the high-performance biomass-based hard carbon material of claim 6, characterized by, The method comprises the following steps: (1) a certain amount of active material, conductive agent and binder are weighed and mixed to obtain a mixed powder; the active material is the high-performance biomass-based hard carbon material of claim 5; (2) a dispersing solvent whose mass is 1-1.5 times that of the mixed powder of step (1) is added, and the active material and the conductive agent are uniformly dispersed by ultrasonic dispersion at a power of 80-100 W for 8-12 min and stirring at a speed of 300-400 r / min for 8-12 h to obtain a composite electrode slurry.

9. The method of claim 8, wherein the solvent is water. In step (1), the conductive agent is carbon black; the binder is PVDF; and the dispersing solvent is selected from one of deionized water, ethanol and NMP; in step (2), the weight ratio of the active material, the conductive agent and the binder in the composite electrode slurry is (6-8):1:(1-2).

10. A method for preparing a metal-ion battery using the high-performance biomass-based hard carbon negative electrode material of claim 6, characterized in that, The method comprises the following steps: a) preparation of an electrode sheet: the high-performance biomass-based hard carbon material of claim 6 is used to prepare a composite electrode slurry, which is coated on a copper foil, dried at 60-80°C for 8-12 h, and then formed into a button-type electrode sheet; b) assembly of a button-type battery: a metal sheet is used as a counter electrode to assemble a button-type battery, which is left to stand for 24-144 h.

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