Preparation method and application of corn straw derived hard carbon material based on multi-step modification strategy
The treatment of corn stalk-derived hard carbon materials through a multi-step modification strategy has solved the problem of insufficient performance in the application of sodium ion battery anode, significantly improved specific capacity and cycle stability, and provided the development idea of high-performance sodium ion battery anode materials.
Patent Information
- Application Number
- CN202510336571.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-21
- Publication Date
- 2025-06-20
AI Technical Summary
In the application of the negative electrode of the corn stalk, the existing hard carbon materials are in the presence of small carbon crystal crystallographic size, many defects, low Coulomb efficiency in the first week, limited specific capacity and poor rate performance.
Multi-step modification strategies are adopted, including acid treatment to remove impurities, catalytic activation of low-temperature alkali metals to regulate pore structure, co-doping of nitrogen and phosphorus to optimize electronic structure, pre-carbonization to form a primary carbon framework, metal ion catalysis and high-temperature carbonization to regulate carbon microcrystalline structure, and residual metal is removed through acid etching to optimize pore distribution.
The electrochemical performance of corn stalk-derived hard carbon materials has been significantly improved, so that their specific capacity reaches ~350mAh g-1 at 0.1C current density, and the capacity retention rate exceeds 80% after 1000 cycles, and long-term stable cycle is achieved at 1C current density, providing a development idea for high-performance sodium ion battery negative electrode materials.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of energy storage materials, and particularly to a preparation method of corn straw-derived hard carbon materials based on a multi-step modification strategy and the application of the hard carbon materials prepared by using the preparation method in electrode plates, especially in the electrode plates of lithium-ion batteries and sodium-ion batteries, and particularly as the anode material. Background Art
[0002] With the growth of global energy demand and the increase in the proportion of renewable energy, high-performance and low-cost energy storage technologies have become an important development direction in the field of energy storage. Sodium-ion batteries have gradually become an important supplement to lithium-ion batteries due to their rich resource reserves, low cost, and environmental friendliness, and show broad application prospects especially in the fields of large-scale energy storage and low-speed electric vehicles. However, due to the relatively large sodium ion radius, the electrode structure is easily damaged during the insertion / extraction process. Therefore, the selection and optimization of the anode material have become the key factors determining the battery performance.
[0003] Hard carbon materials have become a research hotspot for sodium-ion battery anode materials due to their disordered layered structure and large micropore / mesopore specific surface area, which can provide abundant sodium storage sites and exhibit high specific capacity, excellent cycle stability, and good rate performance. In recent years, biomass-based hard carbon materials have received extensive attention due to their wide sources, renewability, and low-cost advantages. Among them, corn straw, as agricultural waste, is rich in carbon precursors and natural microporous structures and has high carbonization potential. However, the current research schemes for corn straw-derived hard carbon materials have relatively large defects, which usually lead to problems such as small carbon microcrystal size, many defects, low first-cycle Coulombic efficiency, limited specific capacity, and poor rate performance, affecting their practical application in sodium-ion battery anodes. Summary of the Invention
[0004] In view of this, to solve the defects existing in the corn straw-derived hard carbon materials in the prior art, on the one hand, the present invention provides a preparation method of corn straw-derived hard carbon materials based on a multi-step modification strategy. By acid treatment, impurities and inorganic salts are removed to improve the carbonization purity; low-temperature alkali metal catalytic activation is used to regulate the pore structure to increase the specific surface area and ion storage capacity; nitrogen and phosphorus co-doping is carried out to optimize the electronic structure and improve the conductivity; pre-carbonization forms a primary carbon skeleton to provide a stable structure for subsequent metal ion catalysis; metal ion catalysis and high-temperature carbonization treatment further regulate the carbon microcrystal structure to enhance the graphitization degree and conductivity; finally, acid etching is used to remove the residual metal, optimize the pore distribution, and enhance the reversible capacity. It can significantly improve the electrochemical performance of the corn straw-derived hard carbon materials, and make their specific capacity reach ~350 mAhg at a current density of 0.1C -1After 1000 cycles, the capacity retention rate exceeds 80%, and long-term stable cycling is achieved at 1C current density (still has excellent performance after 2000 cycles), providing new ideas for the development of high-performance sodium-ion battery negative electrode materials.
[0005] To achieve the above object, the present invention provides the following technical solutions:
[0006] A method for preparing a corn straw-derived hard carbon material based on a multi-step modification strategy comprises the following steps:
[0007] Step (1), precursor selection and pretreatment:
[0008] 1) Grinding corn stalks into particles with a size of 100 to 300 meshes as a precursor;
[0009] 2) treating the precursor with acid to obtain an acid-treated precursor;
[0010] 3) treating the acid-washed precursor with an enzyme to obtain an enzyme-treated precursor;
[0011] Step (2), low temperature alkali metal catalytic activation:
[0012] Activating the enzyme-treated precursor using an alkali metal carbonate to obtain a preliminarily activated hard carbon material;
[0013] Step (3), doping treatment:
[0014] co-doping the initially activated hard carbon material with nitrogen and phosphorus and catalyzing with metal ions to obtain a doped hard carbon material;
[0015] Step (4), high temperature carbonization treatment:
[0016] The doped hard carbon material is subjected to high-temperature carbonization treatment in an inert atmosphere to obtain a hard carbon material.
[0017] Preferably, in step (1), the acid treatment conditions are: using dilute nitric acid with a concentration of 0.5 to 1 M at a temperature of 80 to 100° C. for pickling for 6 to 12 hours.
[0018] Preferably, in step (1), the enzyme treatment conditions are: using cellulase at a temperature of 40 to 60° C. and performing enzymatic hydrolysis for 12 to 24 hours.
[0019] Preferably, the alkali metal carbonate is Na2CO3 or K2CO3.
[0020] Preferably, the mass ratio of the initially activated hard carbon material to the alkali metal carbonate is 1:2 to 1:4.
[0021] Preferably, step (2) is specifically:
[0022] Mix the enzyme-treated precursor with an alkali metal carbonate, stir evenly, and then calcine it in an inert atmosphere at a heating rate of 1-5 °C / min to 400-600 °C for 2-6 h.
[0023] Preferably, step (3) is specifically:
[0024] Soak the preliminarily activated hard carbon material in a urea and disodium hydrogen phosphate solution at a temperature of 80-100 °C for 12-24 h, and at the same time add a metal ion catalyst salt.
[0025] Preferably, the addition amount of the metal ion catalyst salt is 5-10% of the preliminarily activated hard carbon material.
[0026] Preferably, in step (4), heat it at a heating rate of 5-10 °C / min to 1000-1400 °C and keep it warm for 2-3 h.
[0027] In a second aspect, the present invention provides an application of the hard carbon material prepared by the above-mentioned preparation method of the corn straw-derived hard carbon material based on a multi-step modification strategy in an electrode pole piece.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] The hard carbon material prepared by the preparation method of the corn straw-derived hard carbon material based on a multi-step modification strategy provided by the present invention comprehensively improves the material performance through multi-step collaborative optimization, specifically:
[0030] Acid treatment removes impurities, inorganic salts and soluble organic matters, significantly improves the purity of the carbonized product, reduces the interference of non-active components on the electrochemical performance, and improves the carbonization purity.
[0031] Enzyme treatment (cellulase) significantly improves the cellulose degradation efficiency of corn straw. Combined with the following low-temperature alkali metal (Na2CO3 / K2CO3) catalytic activation, a uniform microporous-mesoporous hierarchical structure is formed, providing a fast ion diffusion channel and a high-density storage site for ions. Enzyme treatment avoids the traditional KOH strong alkali activation method (requiring high-temperature concentrated alkali treatment), reduces the discharge of toxic waste liquid, and significantly improves the process safety.
[0032] Low-temperature alkali metal catalytic activation regulates the pore structure, generates a microporous-mesoporous hierarchical structure, increases the specific surface area and ion storage capacity, and provides rich active sites for ion storage.
[0033] Nitrogen and phosphorus co-doping, urea pyrolysis introduces nitrogen atoms, disodium hydrogen phosphate provides phosphorus atoms, optimizes the electron distribution of the carbon layer, reduces the charge transfer impedance, optimizes the electronic structure and improves the conductivity.
[0034] Pre-carbonization forms a primary carbon skeleton, providing a stable structure for subsequent metal-ion catalysis;
[0035] Metal-ion catalysis (such as Fe 3+ , Co 2+ etc.) and high-temperature carbonization treatment further regulate the carbon microcrystal structure, promoting the ordered arrangement of carbon microcrystals. After high-temperature carbonization, the degree of graphitization is close to that of soft carbon, significantly improving the initial efficiency and rate performance, and enhancing the degree of graphitization and conductivity;
[0036] Finally, acid etching is used to remove the residual metal catalyst, avoiding side reactions, while regulating the pore distribution, enhancing the reversible capacity and cycle stability. It can avoid side reactions caused by metal dissolution during battery cycling.
[0037] Verified by experiments, the present invention can significantly improve the electrochemical performance of corn-stalk-derived hard carbon materials, enabling the specific capacity to reach ~350 mAh g at a current density of 0.1C -1 , and the capacity retention rate exceeds 80% after 1000 cycles, and long-term stable cycling can be achieved at a current density of 1C (excellent performance is still maintained after 2000 cycles), providing a new idea for the development of high-performance anode materials for sodium-ion batteries.
[0038] The present invention uses waste corn stalks as the precursor, reducing the raw material cost compared to that of petroleum-based hard carbon. Moreover, it is environmentally friendly, with no highly polluting reagents (such as concentrated sulfuric acid and hydrofluoric acid) throughout the process, and the waste liquid is easy to treat, meeting the trend of green manufacturing. Low-temperature activation is compatible with conventional carbonization equipment, suitable for industrial continuous production, and realizing process scalability.
[0039] The preparation method provided by the present invention can improve the battery performance of hard carbon, especially in terms of specific surface area, porosity, and conductivity, and has good industrial application prospects. Its preparation process is simple, safe, and has low production costs, forming a stable structure and having excellent performance as an anode material for sodium-ion batteries. Detailed implementation methods
[0040] A preparation method of a corn-stalk-derived hard carbon material based on a multi-step modification strategy provided by the present invention includes the following steps:
[0041] Step (1), selection and pretreatment of the precursor:
[0042] 1) Crush corn stalks to a particle size of 100 - 300 mesh as the precursor. Specifically, it can be:
[0043] Mechanically crush the screened corn stalks to obtain small particles with a particle size of 100 - 300 mesh, increasing the surface area and promoting the subsequent acid soaking and activation processes.
[0044] 2) Acid-treat the precursor to obtain the acid-treated precursor.
[0045] Among them, the acid is preferably dilute nitric acid, and the acid treatment conditions are preferably pickling for 6 - 12 h at a temperature of 80 - 100 °C in dilute nitric acid with a concentration of 0.5 - 1 M.
[0046] This step can be preferably:
[0047] Soak the crushed corn straw (precursor) in dilute nitric acid with a concentration of 0.5 - 1 M at a temperature of 80 - 100 °C for 6 - 12 h to remove inorganic impurities and soluble organic substances, improve its structural characteristics, and prepare for subsequent carbonization and modification. Finally, wash with deionized water and dry at 60 - 100 °C.
[0048] 3) Enzyme-treat the acid-washed precursor to obtain the enzyme-treated precursor.
[0049] Among them, the enzyme is preferably cellulase, and the enzyme treatment conditions are preferably: using cellulase at a temperature of 40 - 60 °C for enzymatic hydrolysis reaction for 12 - 24 h.
[0050] This step can be preferably:
[0051] At a temperature of 40 - 60 °C, use cellulase to carry out enzymatic hydrolysis reaction on the acid-treated corn straw for 12 - 24 h, which helps to decompose cellulose, improve the uniformity and pore structure of the precursor, and provide a better skeleton structure for subsequent carbonization.
[0052] Step (2), low-temperature alkali metal catalytic activation:
[0053] Use alkali metal carbonate to activate the enzyme-treated precursor to obtain a preliminarily activated hard carbon material.
[0054] Among them, the alkali metal carbonate is preferably Na2CO3 or K2CO3, and the mass ratio of the preliminarily activated hard carbon material to the alkali metal carbonate is preferably 1:2 - 1:4.
[0055] This step can be:
[0056] Mix the enzyme-treated precursor with alkali metal carbonate, stir evenly, and preferably calcine in an inert atmosphere at a heating rate of 1 - 5 °C / min to 400 - 600 °C for 2 - 6 h. Decompose the carbonate and promote the formation of pore structure, while improving the conductivity and sodium storage capacity of the carbon material. Finally, wash the carbonized and activated material with deionized water to remove the residual alkali metal components on the surface, and then dry to obtain a preliminarily activated hard carbon material. The inert atmosphere is preferably one or several of argon or nitrogen as the inert gas source.
[0057] Step (3), doping treatment:
[0058] The preliminarily activated hard carbon material is subjected to nitrogen and phosphorus co-doping and metal ion catalysis to obtain a doped hard carbon material.
[0059] Among them, the addition amount of the metal ion catalyst salt is preferably 5-10%. This step is preferably:
[0060] The preliminarily activated hard carbon material is soaked in a urea and disodium hydrogen phosphate solution at a temperature of 80-100 °C for 12-24 h. At the same time, 5-10% of the metal ion catalyst salt (Fe 3+ Co 2 + etc.) of the preliminarily activated hard carbon material is added. Urea can introduce nitrogen doping to improve conductivity, while the phosphorus source can optimize the surface chemical properties of hard carbon, and metal ions can promote the evolution of the carbon microcrystalline structure and improve the graphitization degree.
[0061] Step (4), high-temperature carbonization treatment:
[0062] The doped hard carbon material is subjected to high-temperature carbonization treatment in an inert atmosphere to obtain a hard carbon material.
[0063] This step can be: The doped hard carbon material is heated to 1000-1400 °C at a heating rate of 5-10 °C / min and subjected to heat preservation treatment for 2-3 h in a nitrogen or ammonia atmosphere to improve the graphitization degree and optimize the specific capacity and rate performance.
[0064] It may also include step (5), pickling treatment:
[0065] The hard carbon material after high-temperature carbonization is pickled to obtain a hard carbon material without impurities.
[0066] This step can specifically be:
[0067] The hard carbon material after high-temperature carbonization is placed in a dilute hydrochloric acid solution, the temperature is controlled at 50-80 °C, and soaked for 2-4 h to remove the residual metal catalyst, and at the same time optimize the pore structure and surface activity of the carbon material. Finally, it is washed with deionized water until neutral and dried to finally obtain a high-performance hard carbon material.
[0068] In a second aspect, the present invention provides the application of the hard carbon material prepared by the above-mentioned preparation method of the corn straw-derived hard carbon material based on a multi-step modification strategy in electrode plates, especially in electrode plates of lithium-ion batteries and sodium-ion batteries, and particularly as an application of a negative electrode material.
[0069] The technical solutions of the present invention will be clearly and detailedly described below with reference to specific embodiments.
[0070] Example 1
[0071] Preparation method of corn straw-derived hard carbon material based on multi-step modification strategy, comprising the following steps:
[0072] Step (1), selection and pretreatment of precursor:
[0073] 1) First, the screened corn straw is mechanically crushed to obtain small particles with a particle size of 100-300 mesh.
[0074] 2) The crushed corn straw is soaked in 1M dilute nitric acid at 80°C for 12h, and finally washed with deionized water until neutral.
[0075] 3) The acid-treated corn straw is subjected to enzymatic hydrolysis reaction (treated at 50°C for 12h) using cellulase to obtain the enzyme-treated precursor.
[0076] Step (2), low-temperature alkali metal catalytic activation:
[0077] 1) The enzyme-treated precursor and Na2CO3 are mixed according to a mass ratio of 1:2.
[0078] 2) The mixed material is calcined in a nitrogen atmosphere at 550°C for 2h (heating rate 1°C / min), and finally the carbonized and activated material is washed with deionized water to remove the residual alkali metal components on the surface, and finally dried to obtain the preliminarily activated hard carbon material.
[0079] Step (3), doping treatment:
[0080] The preliminarily activated hard carbon material is soaked in a urea and disodium hydrogen phosphate solution at a temperature controlled at 100°C for 12h. At the same time, a certain amount of metal ion catalyst salt (FeCl3, content 10%) is added to obtain the doped hard carbon material.
[0081] Step (4) high-temperature carbonization treatment:
[0082] The doped hard carbon material is subjected to heat preservation treatment in nitrogen at 1200°C for 2h (heating rate 5°C / min) to obtain the high-temperature carbonized hard carbon material.
[0083] Example 2
[0084] Preparation method of corn straw-derived hard carbon material based on multi-step modification strategy, comprising the following steps:
[0085] Step (1), selection and pretreatment of precursor:
[0086] 1) First, the screened corn straw is mechanically crushed to obtain small particles with a particle size of 100-300 mesh.
[0087] 2) Soak the crushed corn straw in 0.5 M dilute nitric acid at 80 °C for 8 h, and finally wash it with deionized water until neutral.
[0088] 3) Carry out an enzymatic hydrolysis reaction on the acid-treated corn straw with cellulase (treatment at 50 °C for 16 h) to obtain a precursor after enzymatic treatment.
[0089] Step (2), low-temperature alkali metal catalytic activation:
[0090] 1) Mix the precursor after enzymatic treatment with Na2CO3 according to a mass ratio of 1:3.
[0091] 2) Calcinate the mixed material in a nitrogen atmosphere at 550 °C for 4 h (heating rate 2 °C / min). Finally, wash the carbonized and activated material with deionized water to remove the residual alkali metal components on the surface, and finally dry it to obtain a preliminarily activated hard carbon material.
[0092] Step (3), doping treatment:
[0093] Soak the preliminarily activated hard carbon material in a urea and disodium hydrogen phosphate solution, control the temperature at 100 °C, and soak for 16 h. At the same time, add a certain amount of metal ion catalyst salt (FeCl3, content 5%) to obtain a doped hard carbon material.
[0094] Step (4), high-temperature carbonization treatment:
[0095] Carry out a heat preservation treatment on the doped hard carbon material under nitrogen at 1300 °C for 3 h (heating rate 10 °C / min) to obtain a hard carbon material after high-temperature carbonization.
[0096] Example 3
[0097] A preparation method of a corn straw-derived hard carbon material based on a multi-step modification strategy, comprising the following steps:
[0098] Step (1), precursor selection and pretreatment:
[0099] 1) First, mechanically crush the screened corn straw to obtain small particles with a particle size of 100-300 mesh.
[0100] 2) Soak the crushed corn straw in 1 M dilute nitric acid at 100 °C for 5 h, and finally wash it with deionized water until neutral.
[0101] 3) Carry out an enzymatic hydrolysis reaction on the acid-treated corn straw with cellulase (treatment at 60 °C for 12 h) to obtain a precursor after enzymatic treatment.
[0102] Step (2), low-temperature alkali metal catalytic activation:
[0103] 1) Mix the enzyme-treated precursor with K2CO3 at a mass ratio of 1:2.
[0104] 2) Calcinate the mixed material in a nitrogen atmosphere at 600 °C for 2 h (heating rate 5 °C / min). Finally, wash the carbonized and activated material with deionized water to remove the residual alkali metal components on the surface, and then dry it to obtain the preliminarily activated hard carbon material.
[0105] Step (3), doping treatment:
[0106] Soak the preliminarily activated hard carbon material in a solution of urea and disodium hydrogen phosphate, control the temperature at 80 °C, and soak for 24 h. At the same time, add a certain amount of metal ion catalyst salt (CoCl2, content 5%) to obtain the doped hard carbon material.
[0107] Step (4), high-temperature carbonization treatment:
[0108] Carry out heat preservation treatment on the obtained doped hard carbon material under nitrogen at 1400 °C for 2 h (heating rate 8 °C / min) to obtain the high-temperature carbonized hard carbon material.
[0109] Example 4
[0110] A preparation method of corn straw-derived hard carbon material based on a multi-step modification strategy, comprising the following steps:
[0111] Step (1), selection and pretreatment of precursor:
[0112] 1) First, mechanically crush the screened corn straw to obtain small particles with a particle size of 100-300 mesh.
[0113] 2) Soak the crushed corn straw in 0.5 M dilute nitric acid at 90 °C for 6 h, and finally wash it with deionized water until neutral.
[0114] 3) Carry out enzymatic hydrolysis reaction on the acid-treated corn straw with cellulase (treatment at 40 °C for 24 h) to obtain the enzyme-treated precursor.
[0115] Step (2), low-temperature alkali metal catalytic activation:
[0116] 1) Mix the enzyme-treated precursor with K2CO3 at a mass ratio of 1:4.
[0117] 2) Calcinate the mixed material in a nitrogen atmosphere at 400 °C for 6 h (heating rate 5 °C / min). Finally, wash the carbonized and activated material with deionized water to remove the residual alkali metal components on the surface, and then dry it to obtain the preliminarily activated hard carbon material.
[0118] Step (3), doping treatment:
[0119] Immerse the activated hard carbon material mentioned above in a solution of urea and disodium hydrogen phosphate, control the temperature at 90 °C, and the immersion time is 12 h. At the same time, add a certain amount of metal ion catalyst salt (CoCl2, content 8%) to obtain a doped hard carbon material.
[0120] Step (4), high-temperature carbonization treatment:
[0121] Carry out heat preservation treatment on the doped hard carbon material under nitrogen at 1000 °C for 3 h (heating rate 8 °C / min).
[0122] Comparative Example 1
[0123] Same as Example 1, except that steps (2) 2) and 3) are not carried out, and other steps are the same.
[0124] Comparative Example 2
[0125] Same as Example 1, except that step (2) is not carried out, and other steps are the same.
[0126] Comparative Example 3
[0127] Same as Example 1, except that step (2) 1) and step (3) are not carried out, and other steps are the same.
[0128] Comparative Example 4
[0129] Same as Example 1, except that the doping treatment in step (3) is not carried out, and other steps are the same.
[0130] Comparative Example 5
[0131] Same as Example 1, except that the temperature in step (4) is changed to 600 °C, and other steps are the same.
[0132] Assemble the negative electrode materials of Examples 1-4 and Comparative Examples 1-5 into coin cells for electrochemical testing. The specific operation is to homogenize the hard carbon materials prepared under different conditions, conductive carbon black, and binder (polyvinylidene fluoride) in a ratio of 8:1:1, uniformly coat them on copper foil, dry them at 60 °C, then roll them to form electrode sheets, and then vacuum dry them at 120 °C for 2 h and place them in a glove box for use. Coin cell assembly method: Cut the electrode sheets of appropriate size as the working electrode, 1 M NaPF6 (ethylene carbonate and diethyl carbonate) (volume ratio 1:1) as the electrolyte, glass fiber as the separator, and a metal sodium sheet of appropriate size as the counter electrode to assemble the coin cell. Test standard: The charge-discharge voltage range of the coin cell is 0.01-3 V, and the charge-discharge rate is 0.1 C. The test results are shown in Table 1:
[0133] Table 1 Performance comparison of Examples 1-4 and Comparative Examples 1-5
[0134]
[0135]
[0136] It can be seen from the comparison of the above table data that Examples 1 to 4 have a relatively high first-cycle reversible capacity (300 mAh g -1 or more), and the capacity of the comparative example is significantly lower. The first efficiency of Examples 1 to 4 is high, more than 80%; the capacity retention rate of Examples 1-4 is good, close to 90%. However, due to the lack of key processing steps in the comparative example, its electrochemical performance will be significantly degraded. These fully illustrate that the special processing method provided by the present patent technology plays a crucial role in the reversible capacity, first efficiency, and capacity retention rate of the hard carbon negative electrode.
[0137] The above is only a preferred specific embodiment of the present invention; however, the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its improved concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.
Claims
1. A method for preparing corn straw-derived hard carbon materials based on a multi-step modification strategy, characterized in that: The steps include: Step (1), precursor selection and pretreatment: 1) Grinding corn stalks into particles with a size of 100 to 300 meshes as a precursor; 2) treating the precursor with acid to obtain an acid-treated precursor; 3) treating the acid-washed precursor with an enzyme to obtain an enzyme-treated precursor; Step (2), low temperature alkali metal catalytic activation: Activating the enzyme-treated precursor using an alkali metal carbonate to obtain a preliminarily activated hard carbon material; Step (3), doping treatment: co-doping the initially activated hard carbon material with nitrogen and phosphorus and catalyzing with metal ions to obtain a doped hard carbon material; Step (4), high temperature carbonization treatment: The doped hard carbon material is subjected to high-temperature carbonization treatment in an inert atmosphere to obtain a hard carbon material.
2. The method for preparing corn straw-derived hard carbon materials based on a multi-step modification strategy according to claim 1, characterized in that: In step (1), the acid treatment conditions are: using dilute nitric acid with a concentration of 0.5 to 1 M at a temperature of 80 to 100° C. for pickling for 6 to 12 hours.
3. The method for preparing corn straw-derived hard carbon materials based on a multi-step modification strategy according to claim 1, characterized in that: In step (1), the enzyme treatment conditions are: using cellulase at a temperature of 40 to 60° C. and performing enzymatic hydrolysis for 12 to 24 hours.
4. The method for preparing corn straw-derived hard carbon materials based on a multi-step modification strategy according to claim 1, characterized in that: In step (2), the alkali metal carbonate is Na2CO3 or K2CO3.
5. The method for preparing corn straw-derived hard carbon materials based on a multi-step modification strategy according to claim 4, characterized in that: The mass ratio of the initially activated hard carbon material to the alkali metal carbonate is 1:2 to 1:
4.
6. The method for preparing corn straw-derived hard carbon materials based on a multi-step modification strategy according to claim 1, characterized in that: Step (2) is specifically as follows: The enzyme-treated precursor is mixed with an alkali metal carbonate, stirred evenly, and then heated to 400-600° C. at a heating rate of 1-5° C. / min and calcined for 2-6 hours in an inert atmosphere.
7. The method for preparing corn straw-derived hard carbon materials based on a multi-step modification strategy according to claim 1, characterized in that: Step (3) is specifically as follows: The initially activated hard carbon material is immersed in a urea and disodium hydrogen phosphate solution at a temperature of 80 to 100° C. for 12 to 24 hours, and a metal ion catalyst salt is added at the same time.
8. The method for preparing corn straw-derived hard carbon materials based on a multi-step modification strategy according to claim 7, characterized in that: The added amount of the metal ion catalyst salt is 5-10% of the initially activated hard carbon material.
9. A method for preparing corn straw-derived hard carbon materials based on a multi-step modification strategy according to any one of claims 1 to 8, characterized in that: In step (4), the temperature is increased to 1000-1400° C. at a heating rate of 5-10° C. / min and kept at this temperature for 2-3 hours.
10. Use of the hard carbon material prepared by the method for preparing corn straw-derived hard carbon material based on a multi-step modification strategy as described in any one of claims 1 to 9 in an electrode plate.