Preparation method of high-yield biomass-based sodium-ion battery hard carbon negative electrode material
By using a hydrothermal carbonization method involving biomass-based materials, transition metal ion catalysts, and acid crosslinking agents, the problems of carbon emissions and equipment pollution in the high-temperature processing of hard carbon anode materials were solved, resulting in high-yield and high-purity hard carbon anode materials and improved electrochemical performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN JANAENERGY TECH CO LTD
- Filing Date
- 2024-04-26
- Publication Date
- 2026-07-07
AI Technical Summary
Existing hard carbon anode materials suffer from high carbon emissions, severe equipment pollution, and low material yield during high-temperature processing, impacting environmental protection and production costs.
A hydrothermal carbonization method combining biomass-based materials with transition metal ion catalysts, acid solutions, and crosslinking agents is employed. This method improves the degree of carbonization, reduces carbonization temperature and time, and decreases volatile gas emissions by forming -O- bonds and aromatization reactions. Furthermore, it reduces impurity content through acid purification.
It improves the yield and purity of hard carbon anode materials, reduces environmental pollution and equipment damage, and enhances electrochemical performance, especially sodium storage capacity and first-cycle coulombic efficiency.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of sodium-ion battery technology, specifically to a method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material. Background Technology
[0002] Compared to lithium-ion batteries, sodium-ion batteries have unique advantages in cost, safety, low-temperature performance, and rate performance, and possess broad commercial prospects. The anode, as a crucial component of sodium-ion batteries, plays a decisive role in their performance. Compared to other types of anode materials, hard carbon anode materials have numerous advantages such as sodium storage capacity, low sodium storage potential, and good cycle stability, making them the most promising sodium storage anode material.
[0003] Hard carbon materials are formed by high-temperature treatment of carbon-containing precursors in an inert gas atmosphere. During the high-temperature treatment, the precursors undergo a series of complex chemical reactions, through the breaking and recombination of chemical bonds, on the one hand, forming a more thermodynamically stable hard carbon structure; on the other hand, the macromolecular structure in the precursors is broken, releasing a series of volatile substances, such as pyrolysis gases like CO, CO2, methane, ethane, and tar.
[0004] During the high-temperature pyrolysis process of the precursor, the pyrolysis gas released has a high carbon content. On the one hand, the large carbon emissions increase greenhouse gas emissions, which is not conducive to achieving the goal of carbon peaking and carbon neutrality. On the other hand, the release of carbon-containing gases reduces the yield of hard carbon itself and increases production costs.
[0005] In addition, a large amount of tar is generated during pyrolysis. Tar is gaseous at temperatures above 300°C, but it is very easy to condense and adhere to the relatively low-temperature furnace and pipeline inner walls, causing problems such as equipment aging and pipeline blockage, which endangers the safe operation of the equipment. Furthermore, the main components of tar are hydrocarbons and various aromatic compounds, which are toxic and harmful to the environment. Summary of the Invention
[0006] The purpose of this invention is to provide a method for preparing high-yield biomass-based sodium-ion battery hard carbon anode material, which features high yield, high purity, and excellent electrochemical performance.
[0007] This invention can be achieved through the following technical solutions:
[0008] This invention discloses a method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material, comprising the following steps:
[0009] S1. Pretreatment: The biomass raw materials are crushed and screened to obtain biomass raw material fragments;
[0010] S2, Hydrothermal carbonization: The biomass raw material fragments, catalyst, acid and crosslinking agent obtained in step S1 are added to the reactor for hydrothermal carbonization to obtain carbonization precursor;
[0011] S3. Precursor purification: The carbonized precursor obtained in step S2 is centrifuged, washed with water and dried to obtain the purified precursor.
[0012] S4. Crushing and powdering: The precursor obtained in step S3 is crushed and powdered to obtain precursor powder.
[0013] S5. High-temperature carbonization: The precursor powder obtained in step S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for biomass-based sodium-ion batteries.
[0014] In the hydrothermal carbonization process of this invention, under acidic conditions, transition metal ions complex with the crosslinking agent and hydroxyl groups in the biomass precursor to form coordination, catalyzing the crosslinking and aggregation between carbonyl groups to form -O- bonds. These -O- bonds are thermodynamically stable and difficult to decompose even at high temperatures (1000°C), ensuring the thermal stability of the hydrothermal carbon during subsequent high-temperature carbonization. Transition metal ions also complex with oxygen-containing functional groups in the biomass precursor. Under high temperature and pressure, these transition metal ions catalyze aromatization and condensation of the biomass precursor, promoting carbonization and graphitization, thereby effectively increasing the degree of carbonization, reducing the carbonization temperature, shortening the carbonization time, and reducing carbonization energy consumption. Metal impurities in the biomass react with the acid under high temperature and pressure, dissolving in the aqueous solution, thus achieving the purpose of purifying the biomass.
[0015] Further, in step S2, the biomass fragments, catalyst, acid and crosslinking agent are in the mass ratio of (65-92):(0.5-3):(5-20):(3-10).
[0016] Furthermore, in step S2, the conditions for hydrothermal carbonization are as follows: heating to 200-400°C at a heating rate of 1-10°C, holding at this temperature for 5-10 hours, and stirring at a speed of 20-200 r / min.
[0017] Furthermore, in step S2, the catalyst is a transition metal ion catalyst, which is one or more of manganese salt, iron salt, copper salt, zinc salt, and chromium salt.
[0018] Further, in step S2, the acid solution is an organic acid and / or an inorganic acid, wherein the organic acid or inorganic acid is one or more of hydrochloric acid, nitric acid, hydrofluoric acid, formic acid, acetic acid, and citric acid.
[0019] Furthermore, the crosslinking agent is a polyhydroxy organic compound, which is one or more of resorcinol, hydroquinone, catechol, ethylene glycol, glycerol, glycerin, polyethylene glycol, and glucose.
[0020] Further, in step S2, the catalyst is one or more of the following: ferric nitrate, copper nitrate, zinc nitrate, copper chloride, zinc chloride, ferric chloride, ferric permanganate, copper permanganate, potassium permanganate, sodium permanganate, potassium chromate, and sodium chromate.
[0021] Furthermore, in step S1, the biomass raw material is one or more of the following: walnut shells, nut shells, bamboo chips, sawdust, sugarcane residue, and straw.
[0022] Furthermore, in step S3, the crushing method is one or more of the following: jaw crusher, roller mill, air jet mill, stirred mill, and ball mill.
[0023] Further, in step S5, the inert gas is nitrogen and / or argon; the high-temperature carbonization conditions are: heating rate 0.5-5 ℃ / min, carbonization temperature 1000-1600 ℃, and carbonization time 2-10 h.
[0024] This invention discloses a method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material, which has the following beneficial effects:
[0025] First, the yield is high. During the hydrothermal carbonization process, the synergistic effect of the transition metal ion catalyst, acid and crosslinking agent promotes the crosslinking and aggregation of carbon precursors while increasing the degree of graphitization. This avoids the generation of a large amount of carbon-containing gas by the high-temperature decomposition of carbon precursors during the subsequent high-temperature heat treatment, thereby increasing the yield and alleviating environmental pollution and equipment damage problems.
[0026] Secondly, the material has high purity. The acid solution can simultaneously purify hard carbon, reduce the ash content of hard carbon materials, and thus improve the purity of the negative electrode material, laying the foundation for improving the performance of battery materials in the future.
[0027] Third, it exhibits excellent electrochemical performance. The negative electrode material of this invention effectively improves the specific capacity and first-cycle coulombic efficiency of hard carbon materials. The reduction in volatile matter effectively reduces the specific surface area of the material and reduces irreversible capacity loss. At the same time, the synergistic effect of multiple components during the hydrothermal process increases the degree of cross-linking and graphitization of carbon precursors, thereby increasing sodium storage active sites and improving the sodium storage capacity of hard carbon materials. Detailed Implementation
[0028] To enable those skilled in the art to better understand the technical solution of the present invention, the product of the present invention will be further described in detail below with reference to embodiments.
[0029] This invention discloses a method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material, comprising the following steps:
[0030] S1. Pretreatment: The biomass raw materials are crushed and screened to obtain biomass raw material fragments;
[0031] S2, Hydrothermal carbonization: The biomass raw material fragments, catalyst, acid and crosslinking agent obtained in step S1 are added to the reactor for hydrothermal carbonization to obtain carbonization precursor;
[0032] S3. Precursor purification: The carbonized precursor obtained in step S2 is centrifuged, washed with water and dried to obtain the purified precursor.
[0033] S4. Crushing and powdering: The precursor obtained in step S3 is crushed and powdered to obtain precursor powder.
[0034] S5. High-temperature carbonization: The precursor powder unaffected by S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for biomass-based sodium-ion batteries.
[0035] Further, in step S2, the biomass fragments, catalyst, acid and crosslinking agent are in the mass ratio of (65-92):(0.5-3):(5-20):(3-10).
[0036] Furthermore, in step S2, the conditions for hydrothermal carbonization are as follows: heating to 200-400°C at a heating rate of 1-10°C, holding at this temperature for 5-10 hours, and stirring at a speed of 20-200 r / min.
[0037] Furthermore, in step S2, the catalyst is a transition metal ion catalyst, which is one or more of manganese salt, iron salt, copper salt, zinc salt, and chromium salt.
[0038] Further, in step S2, the acid solution is an organic acid and / or an inorganic acid, wherein the organic acid or inorganic acid is one or more of hydrochloric acid, nitric acid, hydrofluoric acid, formic acid, acetic acid, and citric acid.
[0039] Furthermore, the crosslinking agent is a polyhydroxy organic compound, which is one or more of resorcinol, hydroquinone, catechol, ethylene glycol, glycerol, glycerin, polyethylene glycol, and glucose.
[0040] Further, in step S2, the catalyst is one or more of the following: ferric nitrate, copper nitrate, zinc nitrate, copper chloride, zinc chloride, ferric chloride, ferric permanganate, copper permanganate, potassium permanganate, sodium permanganate, potassium chromate, and sodium chromate.
[0041] Furthermore, in step S1, the biomass raw material is one or more of the following: walnut shells, nut shells, bamboo chips, sawdust, sugarcane residue, and straw.
[0042] Furthermore, in step S3, the crushing method is one or more of the following: jaw crusher, roller mill, air jet mill, stirred mill, and ball mill.
[0043] Further, in step S5, the inert gas is nitrogen and / or argon; the high-temperature carbonization conditions are: heating rate 0.5-5 ℃ / min, carbonization temperature 1000-1600 ℃, and carbonization time 2-10 h.
[0044] Example 1
[0045] This embodiment relates to a method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material, including the following steps:
[0046] S1. Pretreatment: The walnut shell raw material is crushed and screened to obtain walnut shell fragments with a particle size of less than 2cm.
[0047] S2. Hydrothermal carbonization: Walnut shell fragments, ferric chloride, hydrochloric acid and glycerol obtained in step S1 are added to the reaction vessel in a mass ratio of 78:2:15:5. Water is then added and stirred to obtain a mixed solution. The reaction vessel is heated to 250°C at a heating rate of 5°C and held at this temperature for 8 hours while being stirred at a speed of 30 r / min. After the reaction is completed, the mixture is allowed to cool naturally to obtain the carbonized precursor.
[0048] S3. Precursor purification: The carbonized precursor obtained in step S2 is centrifuged, washed with water, and dried to obtain the purified carbonized precursor.
[0049] S4. Crushing and powdering: The purified carbonized precursor obtained in step S3 is crushed using a roller mill and an air jet mill to obtain precursor powder of a certain fineness.
[0050] S5. High-temperature carbonization: The precursor powder obtained in step S4 is placed in a high-temperature furnace and heated to 1300 °C at a heating rate of 2 °C / min in a nitrogen atmosphere, and held at that temperature for 2 h to obtain hard carbon material.
[0051] The electrochemical performance of the obtained materials was tested as follows: Hard carbon material, Super P, CMC, and SBR were mixed in a mass ratio of 94:1.5:2:2.5 to form a slurry. A 120 μm four-sided coating tool was used to coat the black slurry onto copper foil, and the membrane was then dried in a vacuum oven at 100°C for 2 hours. The electrode membrane was punched into a 0.6 mm radius disc using a die-cutting machine. Using metallic sodium as the counter electrode, 1 mol / L NaClO4EC+DEC (1:1 vol%) as the electrolyte, and a PP / PE / PP three-layer separator, a CR2016 button cell was assembled in a glove box. The above button cell was subjected to constant current charge-discharge testing at a current density of 0.1C (1C = 300 mAh / g) and a voltage range of 2–0.005 V.
[0052] Example 2
[0053] This embodiment relates to a method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material, including the following steps:
[0054] S1. Pretreatment: The walnut shell raw material is crushed and screened to obtain walnut shell fragments with a particle size of less than 2cm.
[0055] S2, hydrothermal carbonization: The walnut shell fragments, zinc nitrate, nitric acid and propylene glycol obtained in step S1 are added to the reactor in a mass ratio of 75:2:15:8. Water is then added and stirred to obtain a mixed solution. The reactor is heated to 300°C at a heating rate of 5°C and held at this temperature for 6 hours while being stirred at a speed of 30 r / min. After the reaction is completed, the reactor is allowed to cool naturally to obtain the carbonized precursor.
[0056] S3. Precursor purification: The carbonized precursor obtained in step S2 is centrifuged, washed with water, and dried to obtain the purified carbonized precursor.
[0057] S4. Crushing and powdering: The hydrothermal carbon obtained in step S3 is crushed using a roller mill and an air jet mill to obtain precursor powder of a certain fineness.
[0058] S5. High-temperature carbonization: Precursor powder of a certain fineness is placed in a high-temperature furnace and heated to 1300 ℃ in a nitrogen atmosphere at a heating rate of 2℃ / min, and held for 2 h to obtain hard carbon material.
[0059] The electrochemical performance of the obtained materials was tested as follows: Hard carbon material, Super P, CMC, and SBR were mixed in a mass ratio of 94:1.5:2:2.5 to form a slurry. A 120 μm four-sided coating tool was used to coat the black slurry onto copper foil, and the membrane was then dried in a vacuum oven at 100°C for 2 hours. The electrode membrane was punched into a 0.6 mm radius disc using a die-cutting machine. Using metallic sodium as the counter electrode, 1 mol / L NaClO4EC+DEC (1:1 vol%) as the electrolyte, and a PP / PE / PP three-layer separator, a CR2016 button cell was assembled in a glove box. The above button cell was subjected to constant current charge-discharge testing at a current density of 0.1C (1C = 300 mAh / g) and a voltage range of 2–0.005 V.
[0060] Comparative Example 1
[0061] This embodiment relates to a method for preparing a hard carbon anode material for a biomass-based sodium-ion battery, including the following steps:
[0062] S1. Pretreatment: The walnut shell raw material is crushed and screened to obtain walnut shell fragments with a particle size of less than 2cm.
[0063] S2. Crushing and powdering: The walnut shell fragments obtained in step S1 are crushed using a roller mill and an air jet mill to obtain walnut shell powder of a certain fineness.
[0064] S3. High-temperature carbonization: Walnut shell powder of a certain fineness is placed in a high-temperature furnace and heated to 1300 ℃ at a heating rate of 2℃ / min in a nitrogen atmosphere, and held at that temperature for 2 h to obtain hard carbon material.
[0065] The electrochemical performance of the obtained materials was tested as follows: Hard carbon material, Super P, CMC, and SBR were mixed in a mass ratio of 94:1.5:2:2.5 to form a slurry. A 120 μm four-sided coating tool was used to coat the black slurry onto copper foil, and the membrane was then dried in a vacuum oven at 100°C for 2 hours. The electrode membrane was punched into a 0.6 mm radius disc using a die-cutting machine. Using metallic sodium as the counter electrode, 1 mol / L NaClO4EC+DEC (1:1 vol%) as the electrolyte, and a PP / PE / PP three-layer separator, a CR2016 button cell was assembled in a glove box. The above button cell was subjected to constant current charge-discharge testing at a current density of 0.1C (1C = 300 mAh / g) and a voltage range of 2–0.005 V.
[0066] Comparative Example 2
[0067] This embodiment relates to a method for preparing a hard carbon anode material for a biomass-based sodium-ion battery, including the following steps:
[0068] S1. Pretreatment: The walnut shell raw material is crushed and screened to obtain walnut shell fragments with a particle size of less than 2cm.
[0069] S2. Hydrothermal carbonization: The walnut shell fragments obtained in step S1 and hydrochloric acid are added to the reactor at a mass ratio of 84:16. Water is then added and stirred to obtain a mixed solution. The reactor is heated to 250°C at a heating rate of 5°C and kept at this temperature for 8 hours. At the same time, the mixture is stirred at a speed of 30 r / min. After the reaction is completed, the mixture is naturally cooled to obtain the carbonized precursor.
[0070] S3. Purification of carbonized precursor: The hydrothermal mixture obtained in step S2 is centrifuged, washed with water, and dried to obtain the purified carbonized precursor.
[0071] S3. Crushing and powdering: The hydrothermal carbon obtained in step S3 is crushed using a roller mill and an air jet mill to obtain precursor powder of a certain fineness.
[0072] S4. High-temperature carbonization: Hydrothermal carbon of a certain fineness is placed in a high-temperature furnace and heated to 1300 ℃ in a nitrogen atmosphere at a heating rate of 2 ℃ / min, and held for 2 h to obtain hard carbon material.
[0073] The electrochemical performance of the obtained materials was tested as follows: Hard carbon material, Super P, CMC, and SBR were mixed in a mass ratio of 94:1.5:2:2.5 to form a slurry. A 120 μm four-sided coating tool was used to coat the black slurry onto copper foil, and the membrane was then dried in a vacuum oven at 100°C for 2 hours. The electrode membrane was punched into a 0.6 mm radius disc using a die-cutting machine. Using metallic sodium as the counter electrode, 1 mol / L NaClO4EC+DEC (1:1 vol%) as the electrolyte, and a PP / PE / PP three-layer separator, a CR2016 button cell was assembled in a glove box. The above button cell was subjected to constant current charge-discharge testing at a current density of 0.1C (1C = 300 mAh / g) and a voltage range of 2–0.005 V.
[0074] The total yields of Examples 1, 2, Comparative Example 1, and Comparative Example 2 were measured to be 30.1%, 32.3%, 21.6%, and 25.4%, respectively, indicating that the synergistic effect of multiple strategies including catalyst, acid, crosslinking agent, and hydrothermal treatment can effectively reduce the volatile matter content and increase the carbon yield during the carbonization process. The ash contents of Examples 1, 2, Comparative Example 1, and Comparative Example 2 were measured to be 0.12%, 0.16%, 1.8%, and 0.10%, respectively, indicating that the acid can effectively reduce the impurity content in the purified hard carbon material.
[0075] Charge-discharge tests revealed that Example 1 had a specific capacity of 315 mAh / g and an initial efficiency of 92%; Example 2 had a specific capacity of 310 mAh / g and an initial efficiency of 91%; Comparative Example 1 had a specific capacity of 285 mAh / g and an initial efficiency of 87%; and Comparative Example 2 had a specific capacity of 295 mAh / g and an initial efficiency of 88%. The specific capacity and initial efficiency of Examples 1 and 2 were effectively improved. This is partly due to the reduction in volatile matter, which effectively decreases the specific surface area of the material, reducing the contact area between the hard carbon material and the electrolyte, minimizing irreversible capacity loss, and thus improving the initial coulombic efficiency of the hard carbon anode. Another reason is the synergistic effect of multiple components during the hydrothermal process, which increases the degree of cross-linking and graphitization of the carbon precursor, thereby increasing the sodium storage active sites and improving the sodium storage capacity of the hard carbon material.
[0076] Table 1 Performance Test Results
[0077]
[0078] Example 3
[0079] This embodiment relates to a method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material, including the following steps:
[0080] S1. Pretreatment: The biomass raw materials are crushed and screened to obtain biomass raw material fragments;
[0081] S2, Hydrothermal carbonization: The biomass raw material fragments, catalyst, acid and crosslinking agent obtained in step S1 are added to the reactor for hydrothermal carbonization to obtain carbonization precursor;
[0082] S3. Precursor purification: The carbonized precursor obtained in step S2 is centrifuged, washed with water and dried to obtain the purified precursor.
[0083] S4. Crushing and powdering: The precursor obtained in step S3 is crushed and powdered to obtain precursor powder.
[0084] S5. High-temperature carbonization: The precursor powder unaffected by S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for biomass-based sodium-ion batteries.
[0085] In step S2 of this embodiment, the biomass fragments, catalyst, acid, and crosslinking agent are in a mass ratio of 92:1.5:5:10. The hydrothermal carbonization conditions are as follows: the temperature is increased to 200°C at a heating rate of 5°C, and held at this temperature for 10 hours, while stirring at a speed of 100 r / min.
[0086] In this embodiment, the catalyst is a transition metal ion catalyst, specifically a manganese salt, such as potassium permanganate or sodium permanganate. The acid solution is an organic acid, such as formic acid, acetic acid, or citric acid. The crosslinking agent is a polyhydroxy organic compound, such as resorcinol or hydroquinone. The biomass raw materials are walnut shells, nut shells, and bamboo strips.
[0087] In step S3 of this embodiment, the crushing method is a jaw crusher and a double roller crusher.
[0088] In step S5 of this embodiment, the inert gases are nitrogen and argon; the high-temperature carbonization conditions are: heating rate 5℃ / min, carbonization temperature 1300℃, and carbonization time 2 h.
[0089] Example 4
[0090] This embodiment relates to a method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material, including the following steps:
[0091] S1. Pretreatment: The biomass raw materials are crushed and screened to obtain biomass raw material fragments;
[0092] S2, Hydrothermal carbonization: The biomass raw material fragments, catalyst, acid and crosslinking agent obtained in step S1 are added to the reactor for hydrothermal carbonization to obtain carbonization precursor;
[0093] S3. Precursor purification: The carbonized precursor obtained in step S2 is centrifuged, washed with water and dried to obtain the purified precursor.
[0094] S4. Crushing and powdering: The precursor obtained in step S3 is crushed and powdered to obtain precursor powder.
[0095] S5. High-temperature carbonization: The precursor powder unaffected by S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for biomass-based sodium-ion batteries.
[0096] In step S2 of this embodiment, the biomass fragments, catalyst, acid, and crosslinking agent are in a mass ratio of 80:0.8:20:7. The hydrothermal carbonization conditions are as follows: heating to 400°C at a heating rate of 1°C, holding at this temperature for 8 hours, and stirring at a speed of 20 r / min.
[0097] In this embodiment, the catalyst is a transition metal ion catalyst, specifically an iron salt, such as ferric nitrate or ferric chloride. The acid solution is an inorganic acid, such as hydrochloric acid, nitric acid, or hydrofluoric acid. The crosslinking agent is a polyhydroxy organic compound, such as catechol or ethylene glycol. The biomass raw materials are nut shells, bamboo chips, and wood chips.
[0098] In step S3 of this embodiment, the pulverizing method is air jet milling or stirring milling.
[0099] In step S5 of this embodiment, the inert gas is nitrogen; the high-temperature carbonization conditions are: heating rate 3 ℃ / min, carbonization temperature 1000℃, and carbonization time 10 h.
[0100] Example 5
[0101] This embodiment relates to a method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material, including the following steps:
[0102] S1. Pretreatment: The biomass raw materials are crushed and screened to obtain biomass raw material fragments;
[0103] S2, Hydrothermal carbonization: The biomass raw material fragments, catalyst, acid and crosslinking agent obtained in step S1 are added to the reactor for hydrothermal carbonization to obtain carbonization precursor;
[0104] S3. Precursor purification: The carbonized precursor obtained in step S2 is centrifuged, washed with water and dried to obtain the purified precursor.
[0105] S4. Crushing and powdering: The precursor obtained in step S3 is crushed and powdered to obtain precursor powder.
[0106] S5. High-temperature carbonization: The precursor powder unaffected by S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for biomass-based sodium-ion batteries.
[0107] In step S2 of this embodiment, the biomass fragments, catalyst, acid, and crosslinking agent are in a mass ratio of 65:3:12:3. The hydrothermal carbonization conditions are as follows: heating to 300°C at a heating rate of 10°C, holding at this temperature for 5 hours, and stirring at a speed of 200 r / min.
[0108] In this embodiment, the catalyst is a transition metal ion catalyst, specifically a copper salt, namely copper chloride. The acid solution consists of organic and inorganic acids, namely hydrochloric acid and citric acid. The crosslinking agent is a polyhydroxy organic compound, namely ethylene glycol, glycerol, glycerol, polyethylene glycol, and glucose. The biomass raw materials are bamboo chips, sawdust, sugarcane bagasse, and straw.
[0109] In step S3 of this embodiment, the pulverizing method is ball milling.
[0110] In step S5 of this embodiment, the inert gas is argon; the high-temperature carbonization conditions are: heating rate 0.5 ℃ / min, carbonization temperature 1600 ℃, and carbonization time 6 h.
[0111] Example 6
[0112] This embodiment relates to a method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material, including the following steps:
[0113] S1. Pretreatment: The biomass raw materials are crushed and screened to obtain biomass raw material fragments;
[0114] S2, Hydrothermal carbonization: The biomass raw material fragments, catalyst, acid and crosslinking agent obtained in step S1 are added to the reactor for hydrothermal carbonization to obtain carbonization precursor;
[0115] S3. Precursor purification: The carbonized precursor obtained in step S2 is centrifuged, washed with water and dried to obtain the purified precursor.
[0116] S4. Crushing and powdering: The precursor obtained in step S3 is crushed and powdered to obtain precursor powder.
[0117] S5. High-temperature carbonization: The precursor powder unaffected by S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for biomass-based sodium-ion batteries.
[0118] In step S2 of this embodiment, the biomass fragments, catalyst, acid, and crosslinking agent are in a mass ratio of 85:2:10:6. The hydrothermal carbonization conditions are as follows: heating to 300°C at a heating rate of 5°C, holding at this temperature for 7 hours, and stirring at a speed of 100 r / min.
[0119] In this embodiment, the catalyst is a transition metal ion catalyst, specifically a zinc salt or chromium salt, namely zinc nitrate, zinc chloride, potassium chromate, or sodium chromate. The acid solution is an organic acid and an inorganic acid, specifically hydrochloric acid, nitric acid, acetic acid, or citric acid. The crosslinking agent is a polyhydroxy organic compound, specifically polyethylene glycol or glucose. The biomass raw materials are walnut shells, nut shells, bamboo chips, sawdust, sugarcane residue, and straw.
[0120] In step S3 of this embodiment, the pulverizing method is a stirred mill or a ball mill.
[0121] In step S5 of this embodiment, the inert gases are nitrogen and argon; the high-temperature carbonization conditions are: heating rate 3℃ / min, carbonization temperature 1300℃, and carbonization time 5 h.
[0122] The above embodiments are merely specific examples of the present invention, and their descriptions are quite specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these obvious substitutions all fall within the protection scope of the present invention.
Claims
1. A method for preparing a high-yield biomass-based sodium-ion battery hard carbon anode material, characterized in that... Includes the following steps: S1. Pretreatment: The biomass raw materials are crushed and screened to obtain biomass raw material fragments; S2. Hydrothermal carbonization: The biomass raw material fragments, catalyst, acid, and crosslinking agent obtained in step S1 are added to a reactor for hydrothermal carbonization to obtain a carbonization precursor; the biomass fragments, catalyst, acid, and crosslinking agent are in a mass ratio of (65-92):(0.5-3):(5-20):(3-10), and the crosslinking agent is a polyhydroxy organic compound, which is one or more of resorcinol, hydroquinone, catechol, ethylene glycol, glycerol, glycerol, polyethylene glycol, and glucose; the hydrothermal carbonization conditions are: heating to 200-400℃ at a heating rate of 1-10℃, holding at this temperature for 5-10h, and stirring at a speed of 20-200r / min; the catalyst is a transition metal ion catalyst, which is one or more of manganese salt, iron salt, copper salt, zinc salt, and chromium salt. S3. Precursor purification: The carbonized precursor obtained in step S2 is centrifuged, washed with water and dried to obtain the purified precursor. S4. Crushing and powdering: The precursor obtained in step S3 is crushed and powdered to obtain precursor powder. S5. High-temperature carbonization: The precursor powder obtained in step S4 is placed in a high-temperature furnace and carbonized at high temperature in an inert gas atmosphere to obtain a hard carbon anode material for biomass-based sodium-ion batteries.
2. The method for preparing high-yield biomass-based sodium-ion battery hard carbon anode material according to claim 1, characterized in that: In step S2, the acid solution is an organic acid and / or an inorganic acid, wherein the organic acid or inorganic acid is one or more of hydrochloric acid, nitric acid, hydrofluoric acid, formic acid, acetic acid, and citric acid.
3. The method for preparing high-yield biomass-based sodium-ion battery hard carbon anode material according to claim 1, characterized in that: In step S2, the catalyst is one or more of the following: ferric nitrate, copper nitrate, zinc nitrate, copper chloride, zinc chloride, ferric chloride, ferric permanganate, copper permanganate, potassium permanganate, sodium permanganate, potassium chromate, and sodium chromate.
4. The method for preparing high-yield biomass-based sodium-ion battery hard carbon anode material according to claim 1, characterized in that: In step S1, the biomass raw material is one or more of the following: nut shells, bamboo chips, sawdust, sugarcane residue, and straw.
5. The method for preparing high-yield biomass-based sodium-ion battery hard carbon anode material according to claim 1, characterized in that: In step S3, the crushing method is one or more of the following: jaw crusher, roller mill, air jet mill, stirred mill, and ball mill.
6. The method for preparing high-yield biomass-based sodium-ion battery hard carbon anode material according to claim 1, characterized in that: In step S5, the inert gas is nitrogen and / or argon; the high-temperature carbonization conditions are: heating rate 0.5-5 ℃ / min, carbonization temperature 1000-1600 ℃, and carbonization time 2-10 h.