Hard carbon material for negative electrode of battery and preparation method therefor, negative electrode sheet, battery, battery pack, and electric device

Abstract

A hard carbon material for a negative electrode of a battery and a preparation method therefor, a negative electrode sheet, a battery, a battery pack, and an electric device. The hard carbon material for the negative electrode of the battery comprises an inner core, which comprises phosphate groups and a plurality of carbon layers, wherein the phosphate groups are located between two adjacent carbon layers.

Description

Hard carbon material for battery negative electrode and preparation method thereof, negative electrode sheet, battery, battery pack and electric device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The present application claims priority to the Chinese patent application No. 202411323424.1, filed on September 20, 2024, and entitled "Hard carbon material for battery negative electrode and preparation method thereof, negative electrode sheet, battery, battery pack and electric device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of batteries, and in particular, to a hard carbon material for battery negative electrode and a preparation method thereof, a negative electrode sheet, a battery, a battery pack and an electric device. BACKGROUND

[0004] Since the radius of sodium ion is larger than that of lithium ion, the graphite negative electrode commonly used in lithium ion batteries cannot be used in sodium ion batteries. In the related art, hard carbon materials with larger spacing and pores are often used in the negative electrode materials of sodium ion batteries. However, the specific capacity of the existing hard carbon materials is low (about 300 mAh / g), and the rate performance is poor, which hinders further industrial application.

[0005] DISCLOSURE

[0006] The present disclosure aims to at least solve one of the technical problems existing in the prior art. To this end, a first object of the present disclosure is to provide a hard carbon material for battery negative electrode, which improves the capacity of the hard carbon material and to some extent improves the rate of the hard carbon material, thereby facilitating the application of the hard carbon material in the battery negative electrode.

[0007] A second object of the present disclosure is to provide a preparation method of a hard carbon material for battery negative electrode.

[0008] A third object of the present disclosure is to provide a negative electrode sheet.

[0009] A fourth object of the present disclosure is to provide a battery.

[0010] A fifth object of the present disclosure is to provide a battery pack.

[0011] A sixth object of the present disclosure is to provide an electric device.

[0012] The hard carbon material for battery negative electrode according to the first aspect of the present disclosure comprises: an inner core, wherein the inner core comprises phosphate and a plurality of carbon layers, and the phosphate is arranged between two adjacent carbon layers.

[0013] According to the hard carbon material for a battery negative electrode provided by the embodiments of the present disclosure, the phosphate is located between the plurality of carbon layers, which increases the spacing between two adjacent carbon layers, so that the ion deintercalation speed is faster, thereby improving the capacity of the hard carbon material and improving the rate of the hard carbon material to a certain extent, and thus facilitating the application of the hard carbon material in the battery negative electrode.

[0014] According to some embodiments of the present disclosure, the spacing between two adjacent carbon layers is d1, wherein the d1 satisfies: 0.36nm≤d1≤0.395nm.

[0015] According to some embodiments of the present disclosure, the Dn50 of the inner core is 2μm-10μm.

[0016] According to some embodiments of the present disclosure, the weight ratio of the phosphate to the carbon layer is: 0.1%-5%.

[0017] According to some embodiments of the present disclosure, the specific surface area of the hard carbon material is a, wherein the a satisfies: 4.2m 2 / g≤a≤4.6m 2 / g; and / or the tap density of the hard carbon material is C, wherein the C satisfies: 1.03g / cm 3 ≤C≤1.11g / cm 3 .

[0018] According to some embodiments of the present disclosure, the hard carbon material further comprises: a hydrocarbon layer, which is coated on the surface of the inner core.

[0019] According to some embodiments of the present disclosure, the thickness of the hydrocarbon layer is d2, wherein the d2 satisfies: 20nm≤d2≤5000nm.

[0020] According to some embodiments of the present disclosure, the weight ratio of the inner core to the hydrocarbon layer is: 100:(0.1-10).

[0021] According to some embodiments of the present disclosure, the elastic modulus of the hard carbon material is 3GPa-5GPa.

[0022] According to the preparation method of the hard carbon material for a battery negative electrode provided by the second aspect of the embodiments of the present disclosure, the method comprises the following steps: mixing a biomass carbon source, a phenolic compound, an aldehyde compound, phosphoric acid or a phosphate, a catalyst and a solvent to obtain a first reaction product; and drying and carbonizing the first reaction product to obtain an inner core.

[0023] According to some embodiments of the present disclosure, the aldehyde compound comprises at least one of aliphatic aldehyde with carbon number of 1-5 and aromatic aldehyde with carbon number of 6-9; and / or the phenolic compound comprises at least one of phenol, substituted phenol and naphthol; and / or the catalyst comprises at least one of hydrochloric acid, sulfuric acid, ammonia, sodium hydroxide, sodium carbonate and sodium bicarbonate; and / or the phosphate comprises at least one of ammonium phosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate and potassium phosphate; and / or the biomass carbon source comprises one or more of coconut shell, rice husk, peanut shell, pinecone, rice, bamboo, corn cob, rape straw and sugar cane residue; and / or the solvent comprises water and / or ethanol.

[0024] According to some embodiments of the present disclosure, the aldehyde compound comprises at least one of formaldehyde, acetaldehyde, butyraldehyde and aromatic aldehyde; and / or the phenolic compound comprises at least one of phenol, cresol, amino phenol, nitro phenol, naphthol and chlorophenol; and / or the volume ratio of water to ethanol is 0-4:1.

[0025] According to some embodiments of the present disclosure, the weight ratio of the catalyst to the solvent is 1:10-50.

[0026] According to some embodiments of the present disclosure, the first reaction product is prepared by hydrothermal reaction, the reaction temperature of the hydrothermal reaction is 80-250℃, the reaction pressure is 0.5-3 MPa, and the reaction time is 1-12 h.

[0027] According to some embodiments of the present disclosure, the carbonization is carried out under inert gas; the carbonization time is 3-15 h, and the carbonization temperature is 800-1500℃; preferably, the inert gas is at least one of nitrogen, helium, neon and argon.

[0028] According to some embodiments of the present disclosure, the drying method is spray drying or freeze drying.

[0029] According to some embodiments of the present disclosure, the carbonization equipment is a box furnace, a tube furnace or a rotary furnace.

[0030] According to some embodiments of the present disclosure, a hydrocarbon source gas is vapor-deposited on the surface of the core to form a hydrocarbon layer.

[0031] According to some embodiments of the present disclosure, the hydrocarbon source gas comprises saturated or unsaturated hydrocarbon group with carbon number of 1-5; preferably at least one of ethyne, propylene, methane and ethylene.

[0032] According to some embodiments of the present disclosure, the weight ratio of the core to the hydrocarbon source gas is 50-5:1.

[0033] According to some embodiments of the present disclosure, the temperature for the vapor deposition is 650-1200℃.

[0034] According to a third aspect of the present disclosure, a negative electrode sheet comprises: the hard carbon material for battery negative electrode according to the first aspect of the present disclosure, or the hard carbon material for battery negative electrode prepared by the preparation method according to the second aspect of the present disclosure.

[0035] According to a fourth aspect of the present disclosure, a battery comprises: the negative electrode sheet according to the third aspect of the present disclosure; and a positive electrode sheet.

[0036] According to a fifth aspect of the present disclosure, a battery pack comprises at least one battery according to the fourth aspect of the present disclosure.

[0037] According to a sixth aspect of the present disclosure, an electrical equipment comprises at least one battery pack according to the fifth aspect of the present disclosure.

[0038] Additional aspects and advantages of the present disclosure will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above and / or additional aspects and advantages of the present disclosure will become apparent and be readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which:

[0040] FIG. 1 is a scanning electron microscope image of the inner core of the hard carbon material of Example 1 according to an embodiment of the present disclosure;

[0041] FIG. 2 is a scanning electron microscope image of the hard carbon material of Example 1 according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0042] The following describes a hard carbon material for battery negative electrode according to a first aspect of the present disclosure.

[0043] According to the first aspect of the present disclosure, the hard carbon material for the battery negative electrode comprises an inner core. Specifically, the inner core comprises phosphate and a plurality of carbon layers, and the phosphate is arranged between two adjacent carbon layers. In the description of the present disclosure, the meaning of "a plurality of" is two or more. The phosphate is arranged between the plurality of carbon layers to increase the spacing between the two adjacent carbon layers, so that the ion deintercalation speed is faster, thereby improving the capacity of the hard carbon material, and to a certain extent, improving the rate of the hard carbon material, and thus facilitating the application of the hard carbon material in the battery negative electrode. In addition, the doping of phosphorus can increase the defect sites of the phosphorus-containing groups of the hard carbon material, which can be used as ion adsorption sites in the "slope region" of the electrochemical curve during the charging and discharging process. For example, in a sodium battery, the defect sites can be used as sodium ion adsorption sites, thereby improving the adsorption and storage capacity of sodium, improving the specific capacity of the sodium battery negative electrode, and the first reversible capacity can reach 380 mAh / g.

[0044] In the present disclosure, the wide-angle total scattering data of the inner core sample can be measured by using high-energy synchrotron radiation, and the Bragg diffraction peak and the diffuse scattering are normalized and transformed to determine the existence of the phosphate structure in the interlayer of the hard carbon.

[0045] According to the hard carbon material for the battery negative electrode of the present disclosure, the phosphate is arranged between the plurality of carbon layers to increase the spacing between the two adjacent carbon layers, so that the ion deintercalation speed is faster, thereby improving the capacity of the hard carbon material, and to a certain extent, improving the rate of the hard carbon material, and thus facilitating the application of the hard carbon material in the battery negative electrode.

[0046] According to some embodiments of the present disclosure, the spacing between the two adjacent carbon layers is d1, wherein d1 satisfies: 0.36 nm≤d1≤0.395 nm. The spacing between the two adjacent carbon layers refers to the vertical spacing between the two adjacent carbon layers arranged in a stack. Therefore, by setting the spacing between the two adjacent carbon layers to 0.36 nm≤d1≤0.395 nm, the spacing between the two adjacent carbon layers is reasonable, the ion storage capacity between the two adjacent carbon layers is large, and the sodium ion transmission speed of the two adjacent carbon layers as the ion transmission channel of sodium ions is fast, thereby improving the rate performance of the battery.

[0047] According to some specific embodiments of the present disclosure, the Dn50 of the inner core is 2 μm-10 μm. Therefore, by controlling the Dn50 of the inner core within 2 μm-10 μm, the particle size of the formed hard carbon material is reasonable, thereby facilitating the improvement of the ion storage capacity and electrochemical cycle performance of the hard carbon material.

[0048] In the present disclosure, Dn50 represents the particle size corresponding to the cumulative volume or mass distribution of 50% in the inner core size distribution, which is tested according to the provisions of GB / T 19077.

[0049] The weight ratio of the phosphate to the carbon layer is 0.1% to 5%, which is beneficial to fully exert the synergistic effect of the phosphate and the carbon layer, thereby improving the structural strength of the core as a support framework, improving the mechanical properties of the hard carbon material, and avoiding waste of the phosphate or the carbon layer, and reducing the cost.

[0050] According to some embodiments of the present disclosure, the specific surface area of the hard carbon material is a, wherein a satisfies: 4.2 m 2 / g≤a≤4.6 m 2 / g. Thus, by controlling the specific surface area of the hard carbon material to be 4.2 m 2 / g≤a≤4.6 m 2 / g, the specific surface area of the hard carbon material is reasonable, which can make the reaction sites and the electrical conductivity of the hard carbon material meet the needs of the battery for ion storage capacity and rate performance, and is also beneficial to controlling the cost of the hard carbon material, thereby reducing the production cost of the battery.

[0051] The tap density of the hard carbon material is C, wherein C satisfies: 1.03 g / cm 3 ≤C≤1.11 g / cm 3 . The tap density refers to the mass of a substance contained in a unit volume after the substance is subjected to a certain vibration or knocking. Thus, by controlling the tap density of the hard carbon material to be in the range of 1.03 g / cm 3 ≤C≤1.11 g / cm 3 , the amount of the hard carbon material filled in the negative electrode is reasonable, which improves the energy density of the battery while reducing the internal structural density of the hard carbon material, so as to improve the ion diffusion speed and improve the charge and discharge performance of the battery.

[0052] According to some embodiments of the present disclosure, the hard carbon material further comprises a hydrocarbon layer, and the hydrocarbon layer is coated on the surface of the core. There is stress in the deintercalation process of ions, and the hydrocarbon layer can provide toughness to the hard carbon material and improve the cycle performance of the hard carbon material. Thus, by coating the hydrocarbon layer on the surface of the core, the core serves as a support framework of the hard carbon network, and the hydrocarbon layer serves as a coating layer on the surface of the core, which improves the mechanical properties of the hard carbon material from the inside and outside of the hard carbon material, improves the ion storage capacity of the hard carbon material under the condition of ensuring the electrochemical cycle performance of the hard carbon material, and is beneficial to the application of the hard carbon material in the negative electrode of the battery.

[0053] According to some embodiments of the present disclosure, the thickness of the hydrocarbon layer is d2, wherein d2 satisfies: 20nm≤d2≤5000nm. In this way, by setting the thickness of the hydrocarbon layer to 20nm≤d2≤5000nm, the coating stability of the hydrocarbon layer on the surface of the core is improved, the electrical conductivity of the hard carbon material is improved, the weight of the hard carbon material is reduced, and the overall performance of the battery is improved.

[0054] According to some embodiments of the present disclosure, the weight ratio of the core and the hydrocarbon layer is 100:(0.1-10). In this way, by setting the weight ratio of the core and the hydrocarbon layer to 100:(0.1-10), the weight ratio of the core and the hydrocarbon layer is reasonable, the hydrocarbon layer can be fully coated outside the core, the uniformity of the hard carbon material is improved, the mechanical properties of the hard carbon material are improved, the specific capacity and rate performance are improved, and the thickness of the hydrocarbon layer is not too large.

[0055] According to some embodiments of the present disclosure, the elastic modulus of the hard carbon material is 3GPa-5GPa. The elastic modulus is used to describe the ability of the hard carbon material to resist deformation. Specifically, when the hard carbon material is subjected to external force, it will deform, and the elastic modulus is an index for measuring the difficulty of such deformation. When the core of the hard carbon material is not coated with a hydrocarbon layer, the elastic modulus of the hard carbon material is less than 3GPa; when the core of the hard carbon material is coated with a hydrocarbon layer, the elastic modulus of the hard carbon material reaches 3GPa-5GPa, so the deformation difficulty of the hard carbon material is reasonable, which is beneficial to the use of the hard carbon material in the battery negative electrode, improves the mechanical strength of the hard carbon material, avoids cracking of the hard carbon material during use, prolongs the service life of the hard carbon material, and improves the use stability of the battery.

[0056] The preparation method of the hard carbon material for the battery negative electrode according to the second aspect of the present disclosure comprises the following steps:

[0057] The biomass carbon source, the phenolic compound, the aldehyde compound, the phosphoric acid or the phosphate, the catalyst and the solvent are mixed to obtain a first reaction product; the first reaction product is dried and carbonized to obtain the core.

[0058] The preparation method of the hard carbon material for the battery negative electrode according to the present disclosure utilizes the phenolic and aldehyde reaction of different types of phenolic and aldehyde compounds to form different internal phenolic and aldehyde resin skeletons, so that the multiple carbon layers and the hard carbon material have stronger mechanical properties, meeting the requirements of various batteries. The above preparation method is relatively simple, thereby improving the preparation efficiency of the hard carbon material, reducing the preparation cost of the hard carbon material, and further controlling the production cost of the battery.

[0059] The first reaction product can be crushed and / or sieved after drying, and then carbonized to obtain the core. Crushing refers to breaking the first reaction product into very small particles by external force; sieving refers to separating the first reaction product according to the size of the particle size by using a screen or other screening tools. In this way, the carbonization completeness of the first reaction product can be increased by crushing and / or sieving, thereby improving the quality of the core and the quality of the hard carbon material, so as to fully play the role of the hard carbon material.

[0060] Further, the aldehyde compound includes at least one of aliphatic aldehyde with carbon atom number of 1-5 and aromatic aldehyde with carbon atom number of 6-9; and / or the phenolic compound includes at least one of phenol, substituted phenol and naphthol; and / or the catalyst includes at least one of hydrochloric acid, sulfuric acid, ammonia, sodium hydroxide, sodium carbonate and sodium bicarbonate; and / or the phosphate includes at least one of ammonium phosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate and potassium phosphate; and / or the biomass carbon source includes one or more of coconut shell, rice husk, peanut shell, pinecone, rice, bamboo, corn cob, rape straw and sugarcane residue; and / or the solvent includes water and / or ethanol.

[0061] Further, the aldehyde compound includes at least one of aliphatic aldehyde with carbon atom number of 1-5 and aromatic aldehyde with carbon atom number of 6-9; and / or the phenolic compound includes at least one of phenol, substituted phenol and naphthol; and / or the catalyst includes at least one of hydrochloric acid, sulfuric acid, ammonia, sodium hydroxide, sodium carbonate and sodium bicarbonate; and / or the phosphate includes at least one of ammonium phosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate and potassium phosphate; and / or the biomass carbon source includes one or more of coconut shell, rice husk, peanut shell, pinecone, rice, bamboo, corn cob, rape straw and sugarcane residue; and / or the solvent includes water and / or ethanol.

[0062] Further, the aldehyde compound includes at least one of formaldehyde, acetaldehyde, butyraldehyde, and aromatic aldehyde. The formaldehyde, acetaldehyde, butyraldehyde, and aromatic aldehyde have a small number of carbon atoms, so that the aldehyde compound has small steric hindrance and high reactivity, thereby reducing the reaction difficulty of the aldehyde compound and the phenolic compound and improving the preparation efficiency of the mixed phenolic aldehyde resin material.

[0063] The phenolic compound includes at least one of phenol, cresol, amino phenol, nitro phenol, naphthol, and chlorophenol. The phenol, cresol, amino phenol, nitro phenol, naphthol, and chlorophenol have a small number of carbon atoms, so that the phenolic compound has small steric hindrance and high reactivity, thereby reducing the reaction difficulty of the phenolic compound and the aldehyde compound and improving the preparation efficiency of the mixed phenolic aldehyde resin material.

[0064] The volume ratio of water and ethanol is 0-4:1. Thus, the volume ratio of water and ethanol is reasonable, and the amount of water and ethanol is controlled, which is beneficial to meet the needs of the hard carbon material.

[0065] According to some embodiments of the present disclosure, the weight ratio of the catalyst to the solvent is 1:10-50. Thus, by setting the weight ratio of the catalyst to the solvent to 1:10-50, the amount of the catalyst and the solvent is reasonable, which meets the needs of the reaction while avoiding excessive waste to reduce the production cost of the hard carbon material.

[0066] According to some specific embodiments of the present disclosure, the first reaction product is prepared by a hydrothermal reaction, the reaction temperature of the hydrothermal reaction is 80-250°C, the reaction pressure is 0.5-3 MPa, and the reaction time is 1-12 h. The hydrothermal reaction refers to a chemical reaction in an aqueous solution under high temperature and high pressure. Such a reaction condition can significantly change the solubility and reactivity of a substance. The reaction temperature, reaction pressure, and reaction time of the hydrothermal reaction are reasonable, which is beneficial to the preparation of the mixed phenolic aldehyde resin material.

[0067] According to other embodiments of the present disclosure, the carbonization is performed under an inert gas, the carbonization time is 3-15 h, and the carbonization temperature is 800-1500°C. The reaction under the inert gas is beneficial to reduce the occurrence of side reactions, thereby improving the quality of the hard carbon material and the cycle performance of the battery. The carbonization time is reasonable, which avoids incomplete carbonization of part of the raw materials due to a short carbonization time and excessive cracking due to a long carbonization time, thereby affecting the quality of the hard carbon material. The carbonization temperature is reasonable, which meets the needs of carbonization, reasonably speeds up the carbonization, and avoids excessive cracking due to a high carbonization temperature, thereby affecting the quality of the hard carbon material.

[0068] Preferably, the inert gas is at least one of nitrogen, helium, neon and argon. Nitrogen, helium, neon and argon are all chemically inert and do not readily react with other substances, thus facilitating the provision of an oxygen-free atmosphere for the reaction, thereby protecting the reactants or products from side effects such as oxidation or hydrolysis.

[0069] According to some embodiments of the present disclosure, the drying method is spray drying or freeze drying. Spray drying is a drying method in which liquid mixed phenolic resin material is dispersed into extremely fine mist droplets in an atomizer by means of a high-speed rotating disc, high-pressure gas or ultrasonic waves, etc., thereby increasing the surface area of the mixed phenolic resin material and facilitating the acceleration of the drying rate. Freeze drying is a drying technique in which the mixed phenolic resin material is first frozen below the freezing point, and then the ice is directly converted into vapor and removed under vacuum conditions, thereby facilitating the preservation of the activity and porosity of the mixed phenolic resin material.

[0070] According to some embodiments of the present disclosure, the carbonization device is a box furnace, a tube furnace or a rotary furnace. The box furnace, the tube furnace or the rotary furnace are adapted to the temperature requirements of carbonization, thereby improving the carbonization effect and ensuring the safety of carbonization.

[0071] According to some embodiments of the present disclosure, the hydrocarbon source gas is vapor-deposited on the surface of the core to form a hydrocarbon layer. The vapor deposition technique has the advantages of good film uniformity, controllability and the ability to prepare complex structures. Thus, the hydrocarbon source gas is deposited on the surface of the core by vapor deposition to form a hydrocarbon layer, which facilitates the improvement of the quality of the hydrocarbon layer to meet the needs of hard carbon materials.

[0072] The hydrocarbon source gas includes a saturated or unsaturated hydrocarbon group with a carbon atom number of 1-5. The above-mentioned hydrocarbon source gas has a wide source and a low price, and the use of the above-mentioned hydrocarbon source gas facilitates the reduction of the cost of hard carbon materials.

[0073] The hydrocarbon source gas is preferably at least one of acetylene, propylene, methane and ethylene.

[0074] According to some embodiments of the present disclosure, the weight ratio of the core to the hydrocarbon source gas is 50-5:1. Thus, by setting the weight ratio of the core to the hydrocarbon source gas to 50-5:1, the coating stability of the hydrocarbon layer on the surface of the core is improved, the electrical conductivity of the hard carbon material is improved, and the weight of the hard carbon material is reduced, which facilitates the improvement of the overall performance of the battery.

[0075] According to some specific embodiments of the present disclosure, the vapor deposition temperature is 650-1200°C. Thus, by setting the vapor deposition temperature to 650-1200°C, the efficiency of vapor deposition is improved, the hydrocarbon layer is stably and reliably coated on the surface of the core, and the hardness and adhesion of the hydrocarbon layer are improved.

[0076] The negative plate according to the third aspect of the present disclosure comprises the hard carbon material for battery negative electrodes according to the first aspect of the present disclosure or the hard carbon material for battery negative electrodes prepared by the preparation method according to the second aspect of the present disclosure.

[0077] The negative plate according to the present disclosure has the above-mentioned hard carbon material, which is beneficial to improve the electrochemical cycle performance of the negative plate and increase the sodium storage capacity of the negative plate.

[0078] The battery according to the fourth aspect of the present disclosure comprises the negative plate and the positive plate, and the negative plate is the negative plate according to the third aspect of the present disclosure.

[0079] The battery according to the present disclosure is beneficial to improve the charge-discharge performance of the battery, prolong the service life of the battery, and improve the market competitiveness of the battery.

[0080] The battery pack according to the fifth aspect of the present disclosure comprises at least one battery according to the fourth aspect of the present disclosure.

[0081] The battery pack according to the present disclosure is beneficial to improve the applicability of the battery pack and improve the market competitiveness of the battery pack.

[0082] The power consumption device according to the sixth aspect of the present disclosure comprises at least one battery pack according to the fifth aspect of the present disclosure.

[0083] The power consumption device according to the present disclosure is beneficial to improve the operation stability of the power consumption device and improve the use experience of the power consumption device.

[0084] The embodiments of the present disclosure are described in detail below. It should be noted that the embodiments described below are exemplary and are used to explain the present disclosure, and cannot be understood as a limitation of the present disclosure. In addition, if not specifically stated, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known methods, and the reaction conditions not listed are also easily obtained by those skilled in the art.

[0085] Embodiment 1

[0086] (1) Take coconut shell (200 g) as a biomass carbon source, 50 g of phenol, 60 g of formaldehyde, 5 g of phosphoric acid, 125 g of ammonia water (25% by mass), and 2000 g of solvent (a volume ratio of 4:1 of ethanol and deionized water), mix uniformly, and then transfer to a high-pressure reaction kettle, react at a temperature of 150℃ and a pressure of 2Mpa for 5h, and obtain a mixed phenolic resin material.

[0087] (2) Take the mixed phenolic resin material at 80°C vacuum drying for 24h, and crush and grade by air flow mill equipment to obtain hard carbon precursor with Dn50 of 6.5μm. Carbonize the core at high temperature in a tube furnace under inert gas Ar atmosphere, keep the carbonization temperature at 1300°C to obtain the core.

[0088] (3) Add the crushed core into the fluidized bed reactor, take nitrogen as the carrier gas, and then add hydrocarbon source gas into the fluidized bed reactor, the hydrocarbon source gas is methane and propylene, the volume ratio of methane to propylene is 1:1.5, and the weight ratio of the core to the hydrocarbon source gas is kept at 100:8.5. Coat and modify the core at a temperature of 900°C to obtain the hard carbon material.

[0089] The distance between the adjacent two carbon layers is 0.395nm, and the thickness of the hydrocarbon layer is 20nm.

[0090] Example 2

[0091] (1) Take sugarcane residue (200g) as the biomass carbon source, 50g of phenol, 60g of formaldehyde, 5g of phosphoric acid, 125g of ammonia water (25% by mass), and 2200g of solvent (volume ratio of ethanol and deionized water is 4:1), mix uniformly, and then transfer to a high-pressure reaction kettle. React at a temperature of 180°C and a pressure of 3Mpa for 3h to obtain a mixed phenolic resin material.

[0092] (2) Take the mixed phenolic resin material at 80°C vacuum drying for 24h, and crush and grade by air flow mill equipment to obtain hard carbon precursor with Dn50 of 7.4μm. Carbonize the core at high temperature in a tube furnace under inert gas Ar atmosphere, keep the carbonization temperature at 1300°C to obtain the core.

[0093] (3) Add the crushed core into the fluidized bed reactor, take nitrogen as the carrier gas, and then add hydrocarbon source gas into the fluidized bed reactor, the hydrocarbon source gas is methane and propylene, the volume ratio of methane to propylene is 1:1.5, and the mass ratio of the core to the hydrocarbon source gas is kept at 100:8.5. Coat and modify the core at a temperature of 900°C to obtain the hard carbon material.

[0094] The distance between the adjacent two carbon layers is 0.388nm, and the thickness of the hydrocarbon layer is 4500nm.

[0095] Example 3

[0096] (1) Take coconut shell (150g) as biomass carbon source, 50g naphthol, 60g acetaldehyde, 5g phosphoric acid, 125g ammonia water (mass fraction is 25%) and 2000g solvent (volume ratio of ethanol and deionized water is 4:1), mix uniformly, then transfer to a high-pressure reaction kettle, react in an environment of 160℃ and 3Mpa for 5h, to obtain a mixed phenolic resin material.

[0097] (2) Take the mixed phenolic resin material and vacuum dry at 80℃ for 24h, then crush and classify by airflow mill equipment, to obtain a hard carbon precursor with Dn50 of 6.2μm, carbonize the inner core in a tube furnace under inert gas Ar atmosphere, keep the carbonization temperature at 1300℃, to obtain the inner core.

[0098] (3) Add the crushed inner core to a fluidized bed reactor, take nitrogen as carrier gas, then add a hydrocarbon source gas to the fluidized bed reactor, the hydrocarbon source gas is methane and propylene, the volume ratio of the hydrocarbon source gas is 1:1.5, and the mass ratio of the inner core to the hydrocarbon source gas is kept at 100:8.5, coat and modify the inner core at a temperature of 900℃, to obtain a hard carbon material.

[0099] Among them, the spacing between two adjacent carbon layers is 0.391nm, and the thickness of the hydrocarbon layer is 3000nm.

[0100] Example 4

[0101] (1) Take coconut shell (200g) as biomass carbon source, 50g phenol, 60g formaldehyde, 3g ammonium phosphate, 75g ammonia water (mass fraction is 25%) and 2000g solvent (volume ratio of ethanol and deionized water is 4:1), mix uniformly, then transfer to a high-pressure reaction kettle, react in an environment of 150℃ and 1.5Mpa for 8h, to obtain a mixed phenolic resin material.

[0102] (2) Take the mixed phenolic resin material and vacuum dry at 80℃ for 24h, then crush and classify by airflow mill equipment, to obtain a hard carbon precursor with Dn50 of 6.0μm, carbonize the inner core in a tube furnace under inert gas Ar atmosphere, keep the carbonization temperature at 1300℃, to obtain the inner core.

[0103] (3) Add the crushed inner core to a fluidized bed reactor, take nitrogen as carrier gas, then add a hydrocarbon source gas to the fluidized bed reactor, the hydrocarbon source gas is methane and propylene, the volume ratio of the hydrocarbon source gas is 1:1.5, and the mass ratio of the inner core to the hydrocarbon source gas is kept at 100:8.5, coat and modify the inner core at a temperature of 900℃, to obtain a hard carbon material.

[0104] The distance between the adjacent two carbon layers is 0.382 nm, and the thickness of the hydrocarbon layer is 3500 nm.

[0105] Example 5

[0106] Example 5 is basically the same as Example 1, except that the weight ratio of the core to the hydrocarbon source gas = 100:0.1, so that the Dn50 of the hard carbon precursor is 6.5 μm, and the distance between the adjacent two carbon layers is 0.395 nm.

[0107] Example 6

[0108] Example 6 is basically the same as Example 1, except that the weight ratio of the core to the hydrocarbon source gas = 100:10, so that the Dn50 of the hard carbon precursor is 6.6 μm, and the distance between the adjacent two carbon layers is 0.391 nm.

[0109] Example 7

[0110] Example 7 is basically the same as Example 1, except that the Dn50 of the hard carbon precursor is 2 μm.

[0111] Example 8

[0112] Example 8 is basically the same as Example 1, except that the Dn50 of the hard carbon precursor is 10 μm.

[0113] Example 9

[0114] Example 9 is basically the same as Example 1, except that the volume ratio of ethanol to deionized water in the solvent is 3:1.

[0115] Example 10

[0116] Example 10 is basically the same as Example 1, except that the solvent is only deionized water.

[0117] Example 11

[0118] Example 11 is basically the same as Example 1, except that the solvent is only ethanol.

[0119] Example 12

[0120] Example 12 is basically the same as Example 1, except that the raw material in step (2) is not subjected to a crushing treatment.

[0121] Example 13

[0122] Example 13 is basically the same as Example 1, except that the hydrocarbon source gas is replaced by argon gas in step (3), so that the hydrocarbon layer cannot be formed on the surface of the core.

[0123] Example 14

[0124] Example 14 is substantially the same as Example 1, except that the reaction temperature in step (1) is 250℃, the reaction pressure is 3 MPa, and the reaction time is 10 h, and the spacing between adjacent carbon layers in the obtained hard carbon material is 0.36 nm.

[0125] Comparative Example 1

[0126] (1) Take coconut shell (200 g) as a biomass carbon source, 50 g of phenol, 60 g of formaldehyde, 125 g of ammonia water (25% by mass), and 2000 g of solvent (a volume ratio of 4:1 of ethanol and deionized water), mix them uniformly, and then transfer them to a high-pressure reaction kettle, and perform a reaction in an environment with a temperature of 150℃ and a pressure of 2 MPa for 5 h to obtain a second reaction product.

[0127] (2) Take the second reaction product and dry it in a vacuum at 80℃ for 24 h, and then perform a crushing and grading operation by using an airflow mill device to obtain a second precursor with a Dn50 of 6.5 μm, and then perform a high-temperature carbonization operation on the second precursor in a tube furnace in an inert gas Ar atmosphere, and maintain the carbonization temperature at 1300℃ to obtain a third reaction product.

[0128] (3) Add the crushed third reaction product to a fluidized bed reactor, use nitrogen gas as a carrier gas, and then add a hydrocarbon source gas to the fluidized bed reactor, the hydrocarbon source gas is methane and propylene, the volume ratio of methane to propylene is 1:1.5, and the weight ratio of the second precursor to the hydrocarbon source gas is maintained at 100:8.5, and then perform a coating modification operation on the second precursor at a temperature of 900℃ to obtain a fourth reaction product.

[0129] In the above process, the raw material does not contain phosphoric acid, the inner core of the fourth reaction product does not contain phosphate, the spacing between adjacent carbon layers in the fourth reaction product is 0.363 nm, and the thickness of the hydrocarbon layer is 20 nm.

[0130] Comparative Example 2

[0131] Comparative Example 2 is substantially the same as Example 1, except that no formaldehyde and phenol are added in step (1), and the phosphate is not arranged between the plurality of carbon layers in the obtained hard carbon material.

[0132] Comparative Example 3

[0133] Take 300 g of phenolic resin dissolved in anhydrous ethanol, add 10 g of hexamethylenetetramine, 30 g of phosphoric acid, stir to dissolve the phenolic resin completely, filter and dry the filtrate in an oven at 80°C; put the dried sample into a tube furnace, heat at a rate of 5°C / min under argon atmosphere, carbonize at 800°C for 3h, ball mill the carbonized sample in a ball mill for 5h, sieve; mix the sieved material with 30 g of medium temperature coal pitch, put it into a tube furnace, heat at a rate of 5°C / min under argon atmosphere, keep it at 600°C for 3h, take out the material, and get the hard carbon material.

[0134] In the above hard carbon material, the phosphate is not arranged between the plurality of carbon layers.

[0135] Performance test

[0136] 1. TEM test was performed on the core and coated hard carbon material of Example 1, and the results are shown in Figures 1 and 2.

[0137] 2. Electrochemical test: According to the China Battery Industry Association group standard T / DCB 010-2024 "Technical requirements for hard carbon negative material for sodium ion battery", the performance tests of interlayer spacing, particle size, specific surface area and tap density of the hard carbon materials prepared in the above examples and the composite materials prepared in the comparative examples were carried out, and the results are shown in Table 1.

[0138] Table 1 Performance test results of each group of materials

[0139] The hard carbon materials prepared in the above examples and the composite materials prepared in the comparative examples were used as anodes, respectively, with a formula of (mass ratio): hard carbon material (composite material): sodium alginate: butadiene rubber: superconducting carbon black: H2O = 90:3:3:4:120, coated on aluminum foil and dried in a vacuum dryer for 16 hours to make anode sheets, with sodium sheets as positive electrodes, electrolyte prepared by dissolving 1 mol NaPF6 in 1 L of electrolyte solvent, wherein the solvent composition is a solution of ethylene carbonate and diethyl carbonate at a volume ratio of 1:1, the separator is a polypropylene microporous membrane, and the button cell is assembled in an argon-filled glove box. The electrochemical performance was tested on a Wuhan Lan electric CT2001A battery tester, with the charge and discharge voltage range controlled at 0.01-2.0V, and the first discharge performance and first efficiency were tested at a charge and discharge rate of 0.1C. The button cell was also tested for rate (5C, 0.1C) and 500 cycle (0.2C / 0.2C) performance. The results are shown in Table 2.

[0140] Table 2 Performance test results of each group of button cells

[0141] In the description of the disclosure, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the disclosure. In the description of the disclosure, the exemplary description of the above terms does not necessarily mean the same embodiment or example.

[0142] Although the embodiments of the disclosure have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the disclosure, and the scope of the disclosure is defined by the claims and their equivalents.

Claims

1. A hard carbon material for use in a battery anode, characterized by, The hard carbon material comprises: a core comprising phosphate and a plurality of carbon layers, the phosphate being arranged between two adjacent carbon layers.

2. The hard carbon material of claim 1, wherein, The distance between the two adjacent carbon layers is d1, wherein the d1 satisfies: 0.36 nm≤d1≤0.395 nm.

3. The hard carbon material of claim 1 or 2, wherein, The Dn50 of the core is 2 μm-10 μm.

4. The hard carbon material of any one of claims 1-3, wherein, The weight ratio of the phosphate to the carbon layers is 0.1%-5%.

5. The hard carbon material of any one of claims 1-4, wherein, The specific surface area of the hard carbon material is a, wherein the a satisfies: 4.2 m 2 / g ≤ a ≤ 4.6 m 2 / g; and / or The tap density of the hard carbon material is C, wherein the C satisfies: 1.03 g / cm 3 ≤ C ≤ 1.11 g / cm 3 .

6. The hard carbon material of any one of claims 1-5, wherein, The hard carbon material further comprises a hydrocarbon layer coated on the surface of the core.

7. The hard carbon material of claim 6, wherein, The thickness of the hydrocarbon layer is d2, wherein the d2 satisfies: 20 nm≤d2≤5000 nm.

8. The hard carbon material of claim 6 or 7, wherein, The weight ratio of the core to the hydrocarbon layer is 100:(0.1-10).

9. The hard carbon material of any one of claims 1-8, wherein, The elastic modulus of the hard carbon material is 3 GPa-5 GPa.

10. A method for producing the hard carbon material for a battery negative electrode according to any one of claims 1 to 9, characterized by, The method comprises the following steps: mixing a biomass carbon source, a phenolic compound, an aldehyde compound, a phosphoric acid or a phosphate, a catalyst and a solvent to obtain a first reaction product; and drying and carbonizing the first reaction product to obtain the core.

11. The method of claim 10, wherein, The aldehyde compound comprises at least one of aliphatic aldehyde with 1-5 carbon atoms and aromatic aldehyde with 6-9 carbon atoms; and / or The phenolic compound comprises at least one of phenol, substituted phenol and naphthol; and / or The catalyst comprises at least one of hydrochloric acid, sulfuric acid, ammonia, sodium hydroxide, sodium carbonate and sodium bicarbonate; and / or The phosphate comprises at least one of ammonium phosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, sodium phosphate and potassium phosphate; and / or The biomass carbon source comprises one or more of coconut shell, rice husk, peanut shell, pinecone, rice, bamboo, corn cob, rape straw and sugar cane residue; and / or The solvent comprises water and / or ethanol.

12. The method of claim 11, wherein, The aldehyde compound comprises at least one of formaldehyde, acetaldehyde, butyraldehyde and aromatic aldehyde; and / or The phenolic compound comprises at least one of phenol, cresol, amino phenol, nitro phenol, naphthol and chlorophenol; and / or The volume ratio of water to ethanol is 0-4:

1.

13. The method of any one of claims 10-12, wherein, The weight ratio of the catalyst to the solvent is 1:10-50.

14. The production method according to any one of claims 10 to 13, characterized by, The first reaction product is prepared by hydrothermal reaction, the reaction temperature of the hydrothermal reaction is 80°C-250°C, the reaction pressure is 0.5 MPa-3 MPa, and the reaction time is 1 h-12 h.

15. The method of any one of claims 10-14, wherein, The carbonization is carried out under inert gas, the carbonization time is 3 h-15 h, and the carbonization temperature is 800°C-1500°C; preferably, the inert gas is at least one of nitrogen, helium, neon and argon.

16. The method of any one of claims 10-15, wherein, The drying method is spray drying or freeze drying.

17. The method of making according to any one of claims 10-16, wherein, The carbonization equipment is a box furnace, a tube furnace or a rotary furnace.

18. The method of any one of claims 10-17, wherein, A hydrocarbon source gas is vapor deposited on the surface of the core to form a hydrocarbon layer.

19. The method of claim 18, wherein, The hydrocarbon source gas comprises a saturated or unsaturated hydrocarbon group with 1-5 carbon atoms; preferably, the hydrocarbon source gas is at least one of acetylene, propylene, methane and ethylene.

20. The method of manufacturing according to claim 18 or 19, wherein, The weight ratio of the core to the hydrocarbon source gas is 50-5:

1.

21. The method of any one of claims 18-20, wherein, The vapor deposition temperature is 650°C-1200°C.

22. A negative electrode sheet characterized by comprising: The hard carbon material comprises: The hard carbon material for use in a battery anode according to any one of claims 1-9, or the hard carbon material for use in a battery anode produced according to the production method of any one of claims 10-21.

23. A battery, characterized by Comprising: an anode sheet, the anode sheet being according to claim 22; and a cathode sheet.

24. A battery pack, characterized by Comprising at least one battery according to claim 23.

25. An electrical device, comprising: Comprising at least one battery pack according to claim 24.

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