CN116947009A - Hard carbon material and preparation method and application thereof - Google Patents

Hard carbon material and preparation method and application thereof Download PDF

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Publication number
CN116947009A
CN116947009A CN202310187779.1A CN202310187779A CN116947009A CN 116947009 A CN116947009 A CN 116947009A CN 202310187779 A CN202310187779 A CN 202310187779A CN 116947009 A CN116947009 A CN 116947009A
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Prior art keywords
hard carbon
carbon material
application
oxygen
containing functional
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Inventor
骆文森
万远鑫
孔令涌
裴现一男
谭旗清
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Shenzhen Dynanonic Innovazone New Energy Technology Co Ltd
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Shenzhen Dynanonic Innovazone New Energy Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The application discloses a hard carbon material and a preparation method and application thereof. The hard carbon material of the present application contains oxygen-containing functional groups, which account for 0.01 to 20wt% of the total weight of the hard carbon material. The hard carbon material provided by the application introduces oxygen-containing functional groups, has relatively large interlayer spacing, increases lithium and sodium storage active sites, remarkably improves reversible deintercalation performance of lithium ions and sodium ions, further improves reversible capacity and rate capability, has good low-temperature performance, and can ensure stable physical and electrochemical performances of the prepared hard carbon material, is high in efficiency and saves production cost.

Description

Hard carbon material and preparation method and application thereof
Technical Field
The application belongs to the field of secondary batteries, and particularly relates to a hard carbon material, a preparation method and application thereof.
Background
The petroleum energy crisis problem in the 60 th and 70 th centuries forces people to find new alternative new energy, and with the enhancement of environmental protection and energy crisis consciousness, new energy is rapidly raised and popularized, and secondary batteries such as lithium ion batteries and sodium ion batteries gradually enter the production and life of society.
With the increasing demand for high quality, low cost products, the secondary battery industry has also placed higher demands on the negative electrode materials of batteries. Research and development of high-capacity, low-cost anode materials has become a focus of attention in the secondary battery industry.
At present, the main commercial materials of the secondary battery are carbon materials with high structural stability and excellent electrochemical performance. The carbon material mainly comprises various carbon materials such as artificial graphite, natural graphite, carbon nanotubes, hard carbon and the like. The hard carbon material is used as amorphous carbon, has higher reversible capacity, theoretically reaches 700 mAh/g-1000 mAh/g, and far exceeds the theoretical capacity 372mAh/g of graphitized carbon, and has a random structure, so that the structural stability in the charge and discharge process can be ensured, and secondary batteries such as lithium batteries, sodium batteries and the like can have longer cycle life and better multiplying power performance.
At present, application reports of hard carbon materials are reported, but in practical application, the existing disclosed hard carbon materials have a larger distance from theoretical capacity, the specific capacity is lower, and the rate capability and low-temperature performance are not ideal.
Disclosure of Invention
The application aims to overcome the defects in the prior art, and provides a hard carbon material and a preparation method thereof, so as to solve the technical problems of unsatisfactory specific capacity, rate capability and low-temperature performance of the existing hard carbon.
The application further aims to provide a negative electrode material, a negative electrode sheet containing the negative electrode material and a secondary battery, so as to solve the technical problems of non-ideal electrochemical performances such as non-ideal capacity density, non-ideal rate performance, non-ideal low-temperature performance and the like of the existing secondary battery containing the hard carbon.
To achieve the above object, according to a first aspect of the present application, there is provided a hard carbon material. The hard carbon material of the present application contains oxygen-containing functional groups, which account for 0.01 to 20wt% of the total weight of the hard carbon material.
The hard carbon material of the application introduces oxygen-containing functional groups, has relatively large interlayer spacing, increases active sites for storing lithium and sodium, remarkably improves reversible deintercalation performance of lithium ions and sodium ions, and further improves reversible capacity. The hard carbon material has high capacity and rate capability and good low-temperature performance.
In a second aspect of the present application, a method of making the hard carbon material of the present application is provided. The preparation method of the hard carbon material comprises the following steps:
pretreating a biomass material, performing mixed acid treatment in inorganic mixed acid, and washing to neutrality to obtain a biomass-based hard carbon precursor;
and (3) carbonizing the biomass-based hard carbon precursor, heating and carrying out sintering quenching treatment to obtain the hard carbon material.
According to the preparation method of the hard carbon material, the biomass material is subjected to oxidation treatment by adopting inorganic mixed acid, so that the biomass-based hard carbon precursor has a specific microstructure and components and contains specific active groups. The biomass-based hard carbon precursor is subjected to carbonization treatment and sintering quenching treatment, so that the produced hard carbon material is rich in oxygen-containing functional groups, has relatively large interlayer spacing, increases lithium and sodium storage active sites, remarkably improves reversible deintercalation performance of lithium ions and sodium ions, and further improves reversible capacity. The hard carbon material has high capacity and rate capability, and good low-temperature performance. In addition, the preparation method of the hard carbon material can ensure that the physical and electrochemical properties of the prepared hard carbon material are stable, the efficiency is high, and the production cost is saved.
In a third aspect of the present application, there is provided a negative electrode material. The anode material of the application also comprises the hard carbon material of the application or the hard carbon material prepared by the preparation method of the hard carbon material of the application.
The negative electrode material contains the hard carbon material, so that the negative electrode material has the advantages of good reversible sodium ion deintercalation performance, high reversible capacity, high rate capability and the like, and good low-temperature performance.
In a fourth aspect of the present application, a negative electrode is provided. The negative electrode of the present application contains the hard carbon material of the present application or the hard carbon material prepared by the preparation method of the hard carbon material of the present application or the negative electrode material of the present application.
The negative electrode of the application contains the hard carbon material, so the negative electrode of the application has high reversible capacity, capacity density, multiplying power performance and other performances and good low-temperature performance.
In a fifth aspect of the present application, there is provided a secondary battery. The application comprises a positive electrode and a negative electrode, wherein the negative electrode is the negative electrode of the application.
The secondary battery of the application has high energy density and multiplying power, stable cycle performance and good low-temperature performance because of the negative electrode of the application.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present application, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic illustration of reactive groups contained in a hard carbon material according to an embodiment of the present application;
FIG. 2 is a schematic flow chart of a method for preparing a hard carbon material according to an embodiment of the present application;
FIG. 3 is an SEM image of a hard carbon material according to example 1;
FIG. 4 is a HRTEM chart of the hard carbon material according to example 1 of the present application;
FIG. 5 is an XRD pattern of a hard carbon material provided in example 1 and comparative example 1 of the present application;
fig. 6 is a raman diagram of a hard carbon material provided in examples 1, 2, and 3 of the present application.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
In the present application, the term "and/or" describes an association relationship of an association object, which means that three relationships may exist, for example, a and/or B may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship.
In the present application, "at least one" means one or more, and "a plurality" means two or more. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
It should be understood that, in various embodiments of the present application, the sequence number of each process described above does not mean that the execution sequence of some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.
The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The weights of the relevant components mentioned in the description of the embodiments of the present application may refer not only to the specific contents of the components, but also to the proportional relationship between the weights of the components, so long as the contents of the relevant components in the description of the embodiments of the present application are scaled up or down within the scope of the disclosure of the embodiments of the present application. Specifically, the mass described in the specification of the embodiment of the application can be mass units known in the chemical industry field such as mu g, mg, g, kg.
The terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated for distinguishing between objects such as substances from each other. For example, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX, without departing from the scope of embodiments of the application. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.
Hard carbon refers to carbon that is difficult to graphitize, and generally refers to thermal decomposition preparation of high molecular weight polymers. Thus, the precursors for the preparation of hard carbon are currently mainly high molecular weight polymers. The present hard carbon is found to have lower capacity than the theoretical capacity and unsatisfactory rate performance and low temperature performance when being applied as the anode material. The inventors have found that the capacity, rate performance and low temperature performance of hard carbon can be improved by subjecting a hard carbon precursor to an acid treatment and a carbonization treatment or the like. Based on this, the present application provides the following scheme.
In a first aspect, embodiments of the present application provide a hard carbon material. The hard carbon material provided by the embodiment of the application contains oxygen-containing functional groups, wherein the oxygen-containing functional groups account for 0.01-20wt% of the total weight of the hard carbon material.
According to the embodiment of the application, the oxygen-containing functional group is introduced into the hard carbon material, and the content of the oxygen-containing functional group is controlled to be 0.01-20wt%, so that the specific surface area and the interlayer spacing can be effectively increased, and the lithium and sodium storage active sites are increased, thereby greatly promoting the bulk phase transmission of lithium ions and sodium ions, remarkably improving the reversible deintercalation performance of the lithium ions and sodium ions, and further improving the reversible lithium or sodium storage capacity. The hard carbon material provided by the embodiment of the application has high capacity and rate capability and good low-temperature performance. In addition, the inventors have further found in the study that, when the content of the oxygen-containing functional group is too low, for example, less than 0.01%, it is difficult to exert the aforementioned effect of the oxygen-containing functional group; if the content is too high, if the content is more than 20wt%, the oxygen functional group will act as a reaction, and the aforementioned effect of the oxygen functional group will be reduced, if the effect of increasing the interlayer spacing is not obvious, the lithium and sodium storage active sites and the bulk transmission of lithium ions and sodium ions will be reduced, and the performances such as lithium storage capacity and sodium storage capacity will be reduced.
In embodiments, the oxygen-containing functional group may further comprise 0.02 to 10wt% of the total weight of the hard carbon material, and still further may comprise 0.02 to 5wt%, and in exemplary embodiments, the oxygen-containing functional group may comprise a typical but non-limiting amount of 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt%, 7wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, etc. of the total weight of the hard carbon material. By adjusting the content of the oxygen-containing functional group, the bulk phase transmission of lithium ions or sodium ions can be further promoted, more reversible lithium and sodium storage sites are exposed, and the reversible lithium and sodium storage capacity is increased. When the hard carbon material provided by the embodiment of the application is used for the anode material of the secondary battery, the rate characteristic, capacity and cycle stability of the secondary battery can be further improved.
Further, the oxygen-containing group contained in the hard carbon material of the embodiment of the application has at least any of the following characteristics:
for example, the oxygen-containing functional group comprises at least one of carbonyl (-C=O), ether (-C-O-C-), carboxyl and hydroxyl, and the functional groups can participate in redox reaction and chemical adsorption of lithium ions and sodium ions, and can help capacitive reversible sodium storage.
At least a portion of the oxygen-containing functional groups are distributed on the surface of the hard carbon material. Specifically, as shown in FIG. 1, oxygen-containing functional groups (e.g., carbonyl and ether groups) are grafted at the ends or edges of the hard carbon material molecular chain.
The oxygen-containing functional groups and the bonding positions of the oxygen-containing functional groups on the hard carbon are specifically combined on the surface of the hard carbon material, so that lithium and sodium storage active sites of the hard carbon material can be further improved, the reversible deintercalation performance of lithium ions and sodium ions is further improved, the reversible capacity, the rate performance and other electrochemical performances of the hard carbon are further improved, and the specific capacity and the rate performance of the hard carbon material in a secondary battery are further improved.
In some embodiments, when the oxygen-containing functional groups distributed on the hard carbon material of the present application contain carbonyl groups, the carbonyl groups may account for 0.01 to 13wt% of the total weight of the hard carbon material, and may further account for 5 to 8wt%. In an exemplary embodiment, the carbonyl-containing groups may be present in an amount of typically, but not limited to, 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt%, 7wt%, 10wt%, 12wt%, 13wt% of the total weight of the hard carbon material.
When the oxygen-containing functional group contains an ether group, the ether group may account for 0.01 to 7wt% of the total weight of the hard carbon material. Further, it may be 1.5 to 2wt%. In an exemplary embodiment, the carbonyl-containing groups may be present in an amount of typically, but not limited to, 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt%, 7wt% and the like based on the total weight of the hard carbon material.
In addition, when the oxygen-containing functional group contains a carbonyl group, the carbonyl group may account for 0.01 to 2wt% of the total weight of the hard carbon material; when the oxygen-containing functional group contains a carbonyl group, the carbonyl group may account for 0.01 to 2wt% of the total weight of the hard carbon material.
When the oxygen-containing functional group of the hard carbon material of the embodiment of the application contains carbonyl and/or ether groups, the reversible deintercalation of lithium ions or sodium ions can be further enhanced by the carbonyl and/or ether groups with the range content, the reversible capacity of the hard carbon material of the embodiment of the application is effectively improved, and other performance characteristics of the hard carbon material including interlayer spacing and the like are further adjusted.
It was examined that, as in the examples, the hard carbon material according to the embodiment of the present application has at least any of the following features (1) to (3):
(1) The interlayer spacing is 0.372 nm-0.410 nm;
(2) The Bragg diffraction angle 2 theta is 2 theta less than or equal to 23.7 degrees;
(3) Degree of graphitization I D /I G ≥1.50。
The inventor researches show that the interlayer spacing of the hard carbon material of the embodiment of the application is relatively increased, for example, between 0.372nm and 0.410nm, and further between 0.375nm and 0.410nm, which is favorable for migration and intercalation and deintercalation of lithium ions or sodium ions. Meanwhile, the Bragg diffraction angle and graphitization degree of the hard carbon material of the embodiment of the application are reduced compared with the existing hard carbon, and the disorder degree is relatively high, for example, the 2 theta of the hard carbon material of the embodiment of the application is less than or equal to 23.7 degrees and I is D /I G More than or equal to 1.50, and further can be 1.50 to 3.0. In an exemplary embodiment, d at 2θ=23.7° of the hard carbon material according to the present application 002 The interlayer spacing was 0.375nm. The hard carbon material has the characteristics, so that the hard carbon material has high capacity density and rate capability and good low-temperature performance.
Further analysis of the hard carbon material according to the present application by the inventors has found that, in some embodiments, the hard carbon material according to the present application has a porous structure, and the porous structure contains micropores, and the micropores have at least any one of the following characteristics (1) to (4):
(1) The aperture of the micropore is 0.35-2 nm;
(2) The pore volume of the micropores is 0.01-0.1 cm 3 /g；
(3) The porosity of the micropores is more than or equal to 90 percent;
(4) The micropores account for more than 90% of the total number of pores contained in the porous structure.
Wherein micropores are understood as pores with a pore diameter of 0.35-2 nm.
As can be seen from the above detection results of the porous structure, the hard carbon material of the embodiment of the application has a rich microporous structure, and the porous structure is mainly micropores. The porous structure with micropores as the main material effectively improves the capacity density of the hard carbon material, has low internal resistance and high rate capability. Meanwhile, the porous structure taking micropores as main pore characteristics endows the hard carbon material of the embodiment of the application with high structural stability, so that the cycle performance of the hard carbon material of the embodiment of the application is improved.
On the basis that the hard carbon material of the embodiment of the application has the porous structure mainly comprising the micropores, in some embodiments, the porous structure of the hard carbon material of the embodiment of the application further comprises mesopores and macropores. The detection shows that in the embodiment, the aperture of the mesopores is 2-50 nm, and the aperture of the macropores is 50-500 nm. Wherein, the mesopores are understood as pores with a pore diameter of 2-50 nm and a pore diameter which does not contain an end value of 2 nm; macropores are understood to be pores with a pore diameter of 50 to 500nm and which do not contain pores with an end value of 50 nm.
In other embodiments, the total number of mesopores and macropores is less than 10% of the total number of pores contained in the porous structure.
The porous structure of the hard carbon material of the embodiment of the application takes micropores as main pores, and the mesopores and macropores are distributed at the same time, so that abundant multi-stage pore spaces can be formed in the porous structure, and the specific surface area of the hard carbon material of the embodiment of the application is enhanced on the basis of effectively improving the volume density and the conductivity, as in some embodiments, the specific surface area of the particles of the hard carbon material of the embodiment of the application can be up to 50-1000 m through detection 2 The ratio of the total weight of the catalyst to the total weight of the catalyst can be 50 to 500m 2 And/g, the contact area of the hard carbon material and the electrolyte is increased, and the mesopores and the macropores are favorable for entering the hard carbon material, so that the migration path of lithium ions or sodium ions is shortened, and the intercalation and deintercalation efficiency of the lithium ions or the sodium ions is improved.
In some embodiments, the hard carbon material of the present application may have a particle diameter D50 of 3 to 15 μm, and further may have a particle diameter of 5 to 8 μm, as measured. This particle size range the hard carbon material particles of the present embodiments have a high tap density. If detected, the tap density of the hard carbon material of the embodiment of the application can reach 0.65-1.3 g/cm 3 Further, it may be 0.65 to 0.80g/cm 3 。
The hard carbon material has the characteristic on the basis of being rich in oxygen-containing functional groups, so that the hard carbon material has rich lithium and sodium storage active sites, high reversible capacity and multiplying power and good low-temperature performance. As detected, the hard carbon material of the present embodiment has at least any one of the following electrochemical properties (1) to (4):
(1) The first charge and discharge capacity can be 250-420 mAh/g, and further can be 350-420 mAh/g;
(2) The first effect can be 70% -90%, and further can be 75% -85%;
(3) The capacity retention rate of 500 circles is more than or equal to 85% under the current density at the temperature of 2 ℃ and the cycle performance, and can further reach 90%;
(4) The reversible capacity is more than or equal to 200mAh/g at the temperature and the multiplying power performance of 5C multiplying power.
In a second aspect, embodiments of the present application also provide a method of preparing the above hard carbon material. The flow of the preparation method of the hard carbon material in the embodiment of the application is shown in the figure 2, and the preparation method comprises the following steps:
s01: pretreating a biomass material, performing mixed acid treatment in inorganic mixed acid, and washing to neutrality to obtain a biomass-based hard carbon precursor;
s02: and (3) carbonizing the biomass-based hard carbon precursor, heating and carrying out sintering quenching treatment to obtain the hard carbon material.
According to the preparation method of the hard carbon material, firstly, the biomass material is subjected to inorganic mixed acid treatment and then is subjected to carbonization treatment and sintering quenching treatment in sequence, so that the prepared hard carbon material has the characteristics of the hard carbon material of the embodiment of the application, such as specific interlayer spacing, bragg diffraction angle, graphitization degree and the like, and further has high capacity density and multiplying power performance and good low-temperature performance. In addition, the preparation method of the hard carbon material can ensure stable physical and electrochemical properties of the prepared hard carbon material, has high efficiency and saves production cost.
Step S01:
the biomass material in step S01 is a raw material as a hard carbon material, and as an example, the biomass material includes at least one of rice, orange peel, sugarcane, rape, cotton, barley (including barley straw, barley grain, and barley products), wheat, corn (including corn stalk and corn cob), reed, sisal, bamboo, peanut, seaweed, towel gourd, pumpkin, jujube wood, oak, peach wood, coconut husk. The inventor researches find that the raw material types of the hard carbon material have a relatively remarkable influence on the microstructure and electrochemical performance of the prepared target hard carbon material, and the prepared hard carbon material has relatively wide interlayer spacing, relatively small Bragg diffraction angle 2 theta and relatively high graphitization degree by selecting the natural biomass materials as raw materials according to the embodiment of the application, compared with other raw materials such as other high molecular polymers, and the characteristics of the interlayer spacing, the Bragg diffraction angle 2 theta, the graphitization degree and the like of the hard carbon material are particularly shown in the embodiment of the application. Meanwhile, after the mixed acid treatment, the prepared hard carbon material has a porous structure, such as a porous structure which is mainly composed of micropores or further contains mesopores and macropores and is contained in the hard carbon material disclosed by the embodiment of the application, the specific surface area of the prepared hard carbon material is increased, and at least one functional group of carbonyl groups and ether groups is enriched, so that the capacity and the multiplying power performance of the prepared hard carbon material are enhanced, and the low-temperature performance is improved.
In the step S01, the biomass material is subjected to oxidation treatment by mixed acid in the mixed acid treatment process, on one hand, light components including water and other biomass components contained in the biomass material are removed, and the biomass material can also act on a carbon skeleton of biomass material organisms, and some oxygen-containing functional groups are grafted on the carbon skeleton, so that the finally generated hard carbon material contains at least one functional group such as carbonyl and ether groups, thereby effectively enhancing the active site of the hard carbon material, improving the electrochemical properties such as capacity, multiplying power performance and the like of the generated hard carbon material, and improving the low-temperature performance.
In an embodiment, the conditions of the mixed acid treatment satisfy at least any one of the following (1) to (3):
(1) The temperature of the mixed acid treatment can be controlled to be 25-100 ℃ and the time can be controlled to be 0.5-10h;
(2) The concentration of the inorganic mixed acid can be 2-8 mol/L; wherein the concentration of the inorganic mixed acid refers to the concentration of the solution of the inorganic mixed acid, and specifically refers to the total molar quantity of the inorganic mixed acid in 1L of the solution of the inorganic mixed acid is 2-8 mol; exemplary, but non-limiting, concentrations may be 2mol/L, 3mol/L, 4mol/L, 5mol/L, 6mol/L, 7mol/L, 8mol/L, etc.;
(3) The mass ratio of the inorganic mixed acid to the biomass material can be 0.7:1 to 3:1, and in the example, may be 0.8: 1. 1: 1. 1.2: 1. 1.5: 1. 1.7: 1.2: 1. 2.5: 1. 2.7: 1. 3:1, etc. typical but non-limiting mass ratio; the inventors have found that if the amount of inorganic mixed acid is reduced, i.e. the impregnation is reduced such as below 0.7:1, the mixed acid treatment effect is weakened; when increasing the amount of inorganic mixed acid, i.e. increasing impregnation, for example above 3:1, would result in an increase in ash, resulting in a decrease in hard carbon performance.
(4) The inorganic mixed acid comprises a mixture of at least two acids selected from phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid. In an exemplary embodiment, the inorganic mixed acid may include an inorganic mixed acid of phosphoric acid and sulfuric acid, an inorganic mixed acid of phosphoric acid and hydrochloric acid, an inorganic mixed acid of phosphoric acid and nitric acid, an inorganic mixed acid of sulfuric acid and hydrochloric acid, an inorganic mixed acid of hydrochloric acid and sulfuric acid, an inorganic mixed acid of nitric acid and hydrochloric acid, an inorganic mixed acid of phosphoric acid and sulfuric acid and hydrochloric acid, an inorganic mixed acid of phosphoric acid and nitric acid, an inorganic mixed acid of phosphoric acid and sulfuric acid and nitric acid, an inorganic mixed acid of nitric acid and sulfuric acid and hydrochloric acid, an inorganic mixed acid of phosphoric acid and sulfuric acid, hydrochloric acid and nitric acid, and the like.
By controlling the conditions of the above embodiment to the mixed acid treatment, the oxidation treatment effect on the biomass material can be improved, and the biomass-based hard carbon precursor is endowed with rich active groups, so that the generated hard carbon material is rich in at least one functional group of carbonyl groups and ether groups, or the prepared hard carbon material is endowed with specific microstructure and components, so that the prepared hard carbon material has a porous structure and a large specific surface area, the reversible capacity and rate performance of the prepared hard carbon material are further improved, and the low-temperature performance is improved.
In the embodiment, the inorganic mixed acid includes an a acid and a B acid based on the conditions of the mixed acid treatment of the (3) and (4), and the mass ratio of the a acid, the B acid and the biomass material may be 0.2 to 1:0.5 to 2:1, a step of; wherein the acid A comprises phosphoric acid and the acid B comprises sulfuric acid. When the inorganic mixed acid contains mixed acid of phosphoric acid and sulfuric acid, such as at the temperature lower than 200 ℃, ionization of the phosphoric acid can make biopolymer in lignocellulose raw materials contained in biomass materials swell and peptize so as to dissolve, and the mixed acid can permeate into the raw materials to dissolve cellulose so as to form pores. Meanwhile, phosphoric acid can also generate a plurality of hydrolysis reactions and oxidation reactions with biomass materials, so that macromolecular compounds are gradually depolymerized to form a uniform plastic substance composed of partial polymers and phosphoric acid, and the preparation of the hard carbon materials with large specific surface area and high specific capacity is facilitated during high-temperature carbonization. The concentrated sulfuric acid plays an oxidizing and dehydrating role, converts hydroxyl, carboxyl and the like in the biomass carbon material into ether groups and carbonyl groups, and the carbonyl (-C=O) and ether (-C-O-C-) functional groups can participate in redox reaction and chemisorption of lithium ions or sodium ions, thereby being beneficial to capacitive reversible lithium or sodium storage. Particularly carbonyl, has high thermal stability and can be reserved at quenching temperature.
In an embodiment, when the mixed acid treatment contains sulfuric acid, the biomass-based hard carbon precursor after the mixed acid treatment containing sulfuric acid is subjected to the carbonization treatment and the sinter quenching treatment in step S02, a small amount of residual carboxyl groups and hydroxyl groups may be present in the hard carbon material, and in an embodiment, the carboxyl groups may be 0.01wt% to 2wt% of the total weight of the hard carbon material, and the hydroxyl groups may be 0.01wt% to 2wt% of the total weight of the hard carbon material.
Other inorganic mixed acids can perform similar functions and effects to the above-mentioned mixed acids of phosphoric acid and sulfuric acid, and of course, other corresponding differences can also occur due to the presence of different acids. But can increase the specific surface area of the prepared hard carbon material, and is rich in at least one functional group of carbonyl groups and ether groups, thereby improving the lithium and sodium storage active sites contained in the prepared hard carbon material, improving the reversible capacity and the rate capability of the prepared hard carbon material, and improving the low-temperature performance.
In addition, the washing treatment after the mixed acid treatment can be water washing to neutrality, and then drying treatment, such as vacuum drying at 60-120 ℃ for 12-24 h.
Step S02:
the biomass-based hard carbon precursor prepared in the step S01 is subjected to carbonization treatment and sintering quenching treatment in the step S02, so that the generated hard carbon material has high conductivity and electrochemical reactivity, more active sites and specific surface areas which can be used for the anode of the lithium ion or sodium ion battery to participate in electrochemical reaction are created under the high temperature effects of carbonization treatment and sintering quenching treatment, and the rate capability and energy density of the lithium ion or sodium ion battery are further improved.
In some embodiments, the carbonization treatment conditions at least satisfy any one of the following (1) to (3):
(1) The carbonization treatment temperature is 300-700 ℃;
(2) The carbonization treatment time is 1-6 h;
(3) The temperature is raised to the carbonization treatment temperature at the temperature raising rate of 5-10 ℃/min.
By the carbonization treatment, the biomass-based hard carbon precursor prepared in step S01 can be sufficiently carbonized, and has more active sites and specific surface area. The carbonization treatment should be performed in a protective atmosphere, for example, a protective atmosphere formed by at least one gas selected from nitrogen, argon, a nitrogen/hydrogen mixed gas, argon/hydrogen, nitrogen/carbon dioxide, and a helium/carbon dioxide mixed gas.
In some embodiments, the conditions of the sinter quenching treatment at least satisfy any one of the following (1) to (3):
(1) The sintering quenching treatment temperature is 1200-1800 ℃;
(2) The sintering quenching treatment time is 1-8 h;
(3) The temperature is raised to the sintering quenching treatment temperature at the heating rate of 0.5-10 ℃/min.
The sintering quenching treatment can further treat the carbonized carbon material at a high temperature, so that the generated hard carbon material not only has rich active sites, but also has the characteristics of interlayer spacing, bragg diffraction angle 2 theta, graphitization degree, actual specific surface area and the like of the hard carbon material according to the embodiment of the application. The sinter quenching treatment should be carried out in a protective atmosphere, for example, the protective atmosphere for the carbonization treatment described above.
In a third aspect, the embodiment of the application also provides a cathode material. The anode material of the embodiment of the application contains the hard carbon material of the embodiment of the application.
Thus, the anode material provided by the embodiment of the application has high capacity and rate performance and high low-temperature performance. Meanwhile, the lithium ion/sodium ion composite material has good conductivity, large contact area with electrolyte and improved lithium ion/sodium ion deintercalation efficiency.
Of course, the anode material of the embodiment of the present application may also contain other components, such as other auxiliary components having anode materials or capable of assisting the anode materials of the embodiment of the present application to function, and the like. When the anode material of the embodiment of the application contains other components, the other components and the anode material of the embodiment of the application can be mixed according to a certain proportion, in particular to improve the anode material of the embodiment of the application to exert the above function as a mixing principle.
In a fourth aspect, an embodiment of the present application further provides a negative electrode. The negative electrode of the embodiment of the application contains the hard carbon material of the embodiment of the application. Because the anode of the embodiment of the application contains the hard carbon material of the embodiment of the application, the anode of the embodiment of the application has high capacity density and rate performance and good low-temperature performance because of containing the hard carbon material of the embodiment of the application.
The negative electrode of the embodiment of the application may be a negative electrode sheet, and in the embodiment, the negative electrode of the embodiment of the application may include a negative electrode current collector and a negative electrode active layer combined with the negative electrode current collector, where the negative electrode active layer contains the hard carbon material of the embodiment of the application.
In one embodiment, the mass content of the hard carbon material of the above text embodiment of the present application contained in the anode active layer may be 80 to 95wt%; further, the content may be 90 to 93wt%. The anode active layer includes a binder and a conductive agent in addition to the hard carbon material, wherein the binder may be a common electrode binder such as one or more of polyvinylidene chloride, soluble polytetrafluoroethylene, styrene-butadiene rubber, hydroxypropyl methylcellulose, carboxymethyl cellulose, polyvinyl alcohol, acrylonitrile copolymer, sodium alginate, chitosan, and chitosan derivatives. In an embodiment of the present application, the conductive agent may be a conventional conductive agent such as one or more including graphite, carbon black, acetylene black, graphene, carbon fiber, C60, and carbon nanotube.
In an embodiment, the preparation process of the negative electrode sheet may be: and mixing the hard carbon material, the conductive agent and the binder to obtain electrode slurry, coating the electrode slurry on a negative electrode current collector, and preparing the negative electrode plate through the steps of drying, rolling, die cutting and the like.
In a fifth aspect, an embodiment of the present application also provides a secondary battery. The secondary battery of the embodiment of the application comprises necessary components such as a positive electrode, a negative electrode and the like, and naturally also comprises other necessary or auxiliary components such as a separator, an electrolyte and the like. The negative electrode is the negative electrode of the embodiment of the application and contains the hard carbon material of the embodiment of the application.
Because the secondary battery of the embodiment of the application contains the hard carbon material of the embodiment of the application, the hard carbon material of the embodiment of the application based on the above text has excellent electrochemical performance, and the secondary battery of the embodiment of the application has high energy density and multiplying power, stable cycle performance and good low-temperature performance.
The hard carbon material, the preparation method and the application thereof and the like according to the embodiment of the application are exemplified by a plurality of specific examples.
1. Hard carbon material and particle size control method example:
example 1
The embodiment provides a hard carbon material and a preparation method thereof. The preparation method of the hard carbon material comprises the following steps:
s1: the orange peel is washed and dried in the sun, then soaked in mixed acid (phosphoric acid concentration: 2mol/L; sulfuric acid concentration: 2 mol/L) according to the following phosphoric acid: sulfuric acid: the mass ratio of the orange peel is 0.2:0.5:1, mixing materials, stirring at room temperature for 2 hours, cleaning to be neutral by using pure boiled water, and vacuum drying at 60 ℃ for 12 hours to obtain a biomass-based hard carbon precursor;
S2: and (3) carbonizing the biomass-based hard carbon precursor prepared in the step (S1) at a heating rate of 5 ℃/min to 300 ℃ for 1h, cooling and crushing, sieving with a 200-mesh sieve, carrying out sintering quenching treatment at a temperature of 1000 ℃, heating rate of 0.5 ℃/min, quenching time of 2h, and naturally cooling to obtain the hard carbon material.
According to detection, the carbonyl content of the hard carbon material of the embodiment is 0.1 weight percent, the ether group content is 0.5 weight percent, and d 00 2-layer spacing of 0.375nm, graphitization degree ID/IG=2.51, microporous porosity of 90%, particle size of 5.2 μm, specific surface area of 58m 2 /g。
Example 2
The embodiment provides a hard carbon material and a preparation method thereof. The preparation method of the hard carbon material comprises the following steps:
s1: s1 in example 1 is different in that phosphoric acid: sulfuric acid: the mass ratio of the orange peel is 0.5:0.9:1.
s2: s2 in example 1 was the same except that the temperature of the sinter quenching treatment was 1100 ℃.
The detection shows that the carbonyl content of the hard carbon material of the embodiment is 3.5 weight percent, the ether group content is 1.5 weight percent, d 00 2-layer spacing of 0.377nm, graphitization degree ID/IG=2.18, microporous porosity of 93%, particle size of 5.7 μm and specific surface area of 216m 2 /g。
Example 3
The embodiment provides a hard carbon material and a preparation method thereof. The preparation method of the hard carbon material comprises the following steps:
s1: rice hulls are washed and dried in the sun and then soaked in mixed acid (phosphoric acid concentration: 2mol/L; sulfuric acid concentration: 3 mol/L) according to the following phosphoric acid: sulfuric acid: the mass ratio of the rice hulls is 0.5:1:1, mixing materials, stirring at room temperature for 3 hours, cleaning to be neutral by using pure boiled water, and vacuum drying at 60 ℃ for 12 hours to obtain a biomass-based hard carbon precursor;
s2: and (3) carbonizing the biomass-based hard carbon precursor prepared in the step (S1) at a heating rate of 6 ℃/min to 700 ℃ for 2 hours, cooling and crushing, sieving with a 200-mesh sieve, carrying out sintering quenching treatment at a temperature of 1200 ℃, heating rate of 1 ℃/min, quenching time of 2 hours, and naturally cooling to obtain the hard carbon material.
The detection shows that the carbonyl content of the hard carbon material of the embodiment is 5.3 weight percent, the ether group content is 2 weight percent, d 00 2-layer spacing of 0.387nm, graphitization degree ID/IG=2.11, microporous porosity of 95%, particle size of 6.10 μm, specific surface area of 241m 2 /g。
Example 4
The embodiment provides a hard carbon material and a preparation method thereof. The preparation method of the hard carbon material comprises the following steps:
S1: s1 in example 3 is different in the concentration of phosphoric acid: 3mol/L; sulfuric acid concentration 3mol/L, phosphoric acid: sulfuric acid: the mass ratio of the rice hulls is 1:1.5:1.
s2: and (3) carbonizing the biomass-based hard carbon precursor prepared in the step (S1) at a heating rate of 0.5 ℃/min to 500 ℃ for 3 hours, cooling and crushing, sieving with a 200-mesh sieve, performing sintering quenching at a temperature of 1200 ℃, heating at a heating rate of 0.5 ℃/min for 4 hours, and naturally cooling to obtain the hard carbon material.
The detection shows that the carbonyl content of the hard carbon material of the embodiment is 5.5 weight percent, the ether group content is 2.6 weight percent, d 00 2-layer spacing of 0.392nm, graphitization degree ID/IG=2.45, microporous porosity of 95%, particle size of 6.5 μm, specific surface area of 358m 2 /g。
Example 5
The embodiment provides a hard carbon material and a preparation method thereof. The preparation method of the hard carbon material comprises the following steps:
s1: s1 in example 3 is different in the concentration of phosphoric acid: 8mol/L; sulfuric acid concentration of 8mol/L, phosphoric acid: sulfuric acid: the mass ratio of the rice hulls is 0.5:2:1.
s2: s2 in example 3.
According to detection, the carbonyl content of the hard carbon material of the embodiment is 13 weight percent, the ether group content is 7 weight percent, d 00 2-layer spacing of 0.410nm, graphitization degree ID/IG=2.35, microporous porosity of 98%, particle size of 7.5 μm, specific surface area of 479m 2 /g。
Comparative example 1
The comparative example provides a hard carbon material and a preparation method thereof. The preparation method of the hard carbon material of the comparative example comprises the following steps:
s1, cleaning orange peel, carbonizing at a heating rate of 5 ℃/min to 300 ℃ for 1h, cooling and crushing, sieving with a 200-mesh sieve, sintering and quenching at a temperature of 1000 ℃ at a heating rate of 0.5 ℃/min for 2h, and naturally cooling to obtain the hard carbon anode material.
Through detection, the hard carbon material d of the comparative example 00 2-layer spacing of 0.350nm, graphitization degree ID/IG=1.01, microporous porosity of 53%, particle size of 3.2um and specific surface area of 30m 2 /g。
2. Sodium ion battery example:
the hard carbon materials provided in examples 1 to 5 and the hard carbon materials provided in comparative examples described above were assembled into a negative electrode and a sodium ion battery, respectively, as follows:
and (3) a negative electrode: the hard carbon negative electrode materials, polyvinylidene fluoride, SP-Li provided in examples 1 to 5 and comparative example 1, respectively, were prepared in a ratio of 90:5:5, carrying out mixed ball milling to obtain negative electrode slurry, coating the negative electrode slurry on the surface of a copper foil, rolling, and vacuum drying overnight at 110 ℃ to obtain a negative electrode plate;
A counter electrode: sodium metal sheet;
electrolyte solution: 1.0M NaPF 6 /EC:DEC＝1:1Vol％；
A diaphragm: 20. Mu. MPP/PE/PP separator (glass fiber separator) was used;
sodium ion battery assembly: the sodium ion batteries were assembled in an inert atmosphere glove box in the order of assembling the sodium metal sheet-separator-electrolyte-negative electrode sheet, the batteries containing the negative electrodes of the hard carbon materials provided in examples 1 to 5 were respectively denoted as examples S1 to S5, and the battery containing the hard carbon material of comparative example 1 was denoted as comparative example D1.
3 correlation Performance test
3.1 hard carbon Performance test
The hard carbon materials provided in examples 1 to 5 and comparative example 1 were subjected to Scanning Electron Microscopy (SEM), high Resolution Transmission Electron Microscopy (HRTEM) and X-ray diffraction (XRD) analysis, respectively. The analysis results were as follows:
SEM results: the SEM of the hard carbon material provided in example 1 is shown in fig. 3, and the SEM of the hard carbon material provided in other examples is similar to fig. 3. From the SEM image, the hard carbon material is in a block shape, and a small amount of macroporous structures exist on the surface.
HRTEM results: HRTEM of hard carbon material provided in example 1 is shown in fig. 4, and other examples provide HRTEM patterns of hard carbon material similar to fig. 4. According to the HRTEM diagram, the hard carbon material is in a disordered structure, and the graphitization degree is low, so that the carbon material prepared by the embodiment of the application is proved to be hard carbon.
XRD results: XRD patterns of the hard carbon materials provided in example 1 and comparative example 1 are shown in fig. 5, and XRD patterns of the hard carbon materials provided in other examples are similar to those of example 1. From the XRD pattern, it was found that the hard carbon material prepared by sintering after the mixed acid treatment had two diffraction peaks, and the first diffraction angle was smaller and the interlayer spacing at the corresponding d002 position was larger.
Raman graph results: the raman spectra of the hard carbon anode materials provided in examples 1-3 show that the graphitization degree of the hard carbon materials prepared by sintering after mixed acid treatment is reduced, and the disorder degree is increased.
In addition, based on the SEM, HRTEM, XRD and raman chart analysis, the biomass-based hard carbon precursor prepared in step S1 and the hard carbon material prepared in step S2 of each example were further characterized in relation to each other, and other characteristics of the biomass-based hard carbon precursor and the hard carbon material were examined, and the biomass-based hard carbon precursor and the hard carbon material at least have the following characteristics:
a. after the mixed acid treatment in the step S1, developed micropores (the pore diameter of the micropores is less than or equal to 2 nm) are introduced on the surface of the biomass-based hard carbon precursor; the particle size of the biomass-based hard carbon precursor is 3-5 mu m, and the particle size of the hard carbon material D50 generated after carbonization treatment and sintering quenching treatment in the step S2 is changed into 3-15 mu m, and further 5-8 mu m;
b. Micropore volume (pore volume) of biomass-based hard carbon precursor is less than 0.001cm 3 The porosity of micropores is less than 60 percent, and the specific surface area is less than 30m 2 And/g. Hard carbonThe micropore volume (pore volume) of the material is increased to 0.01-0.1 cm 3 Per gram, the microporous porosity is increased to be more than or equal to 90 percent, and the specific surface area is enlarged to be 50 to 1000m 2 And/g, further 50 to 500m 2 /g；
c. The biomass-based hard carbon precursor has an interlayer spacing of < 0.370, a bragg diffraction angle 2θ=24.0°, a d002 interlayer spacing of 0.370nm at 2θ=24.0°, and a graphitization degree (ID/IG) of 2.01. The interlayer spacing of the hard carbon material increases to 0.372 to 0.410nm, further 0.375 to 0.410nm (increasing trend), the Bragg diffraction angle 2θ decreases to be less than or equal to 23.7 ° (the diffraction angle becomes smaller), such as the d002 interlayer spacing at 2θ=23.7° is 0.375nm, and the graphitization degree (ID/IG) is 2.47 (normal value is generally between 1.0 and 3.5). Wherein, the greater the graphitization degree (ID/IG, the higher the disorder degree, i.e. the lower the graphitization degree);
e. the oxygen-containing functional groups of the biomass-based hard carbon precursor and hard carbon material are distributed mainly at the edges, as shown in fig. 1: mainly comprises carbonyl and ether groups (reversible deintercalation of sodium can be realized, and reversible capacity is increased); wherein, the content of carbonyl (-C=O) contained in the biomass-based hard carbon precursor is less than or equal to 3wt%, and the content of ether (-C-O-C-) is less than 1.5wt%; the content of carbonyl C=O in the hard carbon material is increased to 5-13 wt%, and the content of ether C-O is increased to 1.5-7 wt%.
f. The hard carbon material contains a porous structure, and the distribution of the porous structure is as follows: micropores: 0.35-2 nm, with the ratio more than or equal to 90 percent; the ratio of the medium holes (2-50 nm) to the large holes (50-500 nm) is less than 10%;
and the higher the degree of order or graphitization of the hard carbon material increases with an increase in the temperature of the sinter quenching treatment in step S02, the higher the first effect will be, and the capacity will be increased and then decreased.
3.2 sodium ion Battery related Performance test
The electrochemical performance of each sodium ion battery assembled in the sodium ion battery embodiment is tested, and the test conditions are as follows: the charge-discharge voltage ranges from 5mV to 3.0V, and the first discharge capacity and the corresponding first coulombic efficiency at 0.1C and the electrochemical performance of 500 cycles of 1C and 3C circulation at the low temperature of-25 ℃ and the normal temperature of 25 ℃ are tested.
The electrochemical properties associated with sodium ion cells are shown in table 1 below:
TABLE 1
From the data results of the examples and comparative examples in table 1, it can be seen that: under the condition of charging and discharging at different multiplying powers, the battery assembled by the sodium ion battery cathode material prepared by the application has better initial charge specific capacity, initial effect, low temperature and normal temperature performance than the comparative example, because the hard carbon material prepared by the embodiment of the application is subjected to inorganic mixed acid and low-high temperature sintering treatment, a plurality of oxygen functional groups are introduced on the surface of the carbon material, the conductivity of the carbon material is enhanced, more sodium ion reaction active sites are introduced, and the hard carbon d is improved 002 The interlayer spacing widens the transmission channel of active sodium ions and reduces the diffusion transmission resistance of sodium ions between layers, thereby improving the specific capacity, first effect and cycle performance of the hard carbon anode material. Further comparing examples 1 to 5, it was found that the higher the oxygen functional group content of the hard carbon material of the present application was, the better the corresponding electrochemical performance was, but the electrochemical performance of the hard carbon material of the present application could be relatively significantly improved when the content was moderate, and the electrochemical performance of the hard carbon material provided in example 3 was significantly better than that of the hard carbon material of other examples.
The foregoing examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims (12)

1. A hard carbon material, characterized in that the hard carbon material contains oxygen-containing functional groups, the oxygen-containing functional groups account for 0.01 to 20wt% of the total weight of the hard carbon material.
2. The hard carbon material of claim 1, wherein: the oxygen-containing group has at least any one of the following characteristics:
the oxygen-containing functional group comprises at least one of carbonyl, ether, carboxyl and hydroxyl;
at least a portion of the oxygen-containing functional groups are distributed on the surface of the hard carbon material.
3. The hard carbon material of claim 2, wherein: the oxygen-containing functional group comprises carbonyl, and the carbonyl accounts for 0.01-13 wt% of the total weight of the hard carbon material; and/or
The oxygen-containing functional group comprises an ether group, and the ether group accounts for 0.01-7wt% of the total weight of the hard carbon material.
4. A hard carbon material according to any one of claims 1 to 3, wherein: the hard carbon material has at least any one of the following characteristics:
the interlayer spacing is 0.372 nm-0.410 nm;
the Bragg diffraction angle 2 theta is 2 theta less than or equal to 23.7 degrees;
graphitization degree I D /I G ≥1.50；
The hard carbon material comprises a porous structure.
5. The hard carbon material of claim 4, wherein: the porous structure contains micropores, and the micropores have at least any one of the following characteristics:
the aperture of the micropore is 0.35-2 nm;
the pore volume of the micropores is 0.01-0.1 cm 3 /g；
The porosity of the micropores is more than or equal to 90%;
The micropores account for more than 90% of the total number of pores contained in the porous structure.
6. The hard carbon material of claim 5, wherein: the porous structure further comprises mesopores and macropores, wherein,
the aperture of the mesopore is 2-50 nm, and the aperture of the macropore is 50-500 nm; or/and (or)
The total number of mesopores and macropores is 10% or less of the total number of pores contained in the porous structure.
7. The hard carbon material according to any one of claims 1 to 3, 5 to 6, wherein: the particles of hard carbon material have at least any of the following characteristics:
specific surface area of 50-1000 m 2 /g；
The D50 particle size is 3-15 mu m.
8. The hard carbon material according to any one of claims 1 to 3, 5 to 6, wherein: the hard carbon material has at least any one of the following electrochemical properties:
the first charge-discharge capacity is 250-420 mAh/g;
the first effect is 70% -90%;
the tap density is 0.65-1.3 g/cm 3 ；
The cycle performance at the temperature and the current density of 2C is 500 circles, and the capacity retention rate is more than or equal to 85 percent;
the reversible capacity is more than or equal to 200mAh/g at the temperature and the multiplying power performance of 5C multiplying power.
9. A method for preparing a hard carbon material, characterized by comprising the following steps:
pretreating a biomass material, performing mixed acid treatment in inorganic mixed acid, and washing to neutrality to obtain a biomass-based hard carbon precursor;
And (3) carbonizing the biomass-based hard carbon precursor, heating and carrying out sintering quenching treatment to obtain the hard carbon material.
10. The method of preparing as claimed in claim 9, wherein: the conditions of the mixed acid treatment at least meet any one of the following conditions:
the concentration of the inorganic mixed acid is 2-8 mol/L;
the mass ratio of the total mass of the inorganic mixed acid to the biomass material is (0.7-3): 1, a step of;
the temperature is 25-100 ℃ and the time is 0.5-10h;
the inorganic mixed acid comprises a mixture of at least two acids of phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid.
11. A negative electrode material characterized in that: comprising the hard carbon material according to any one of claims 1 to 8 or the hard carbon material produced by the production method according to claim 9 or 10.
12. A secondary battery comprising a positive electrode and a negative electrode, characterized in that: the negative electrode comprising the negative electrode material according to claim 11.
CN202310187779.1A 2023-02-22 2023-02-22 Hard carbon material and preparation method and application thereof Pending CN116947009A (en)

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