Carbonaceous material, method for producing the same, and secondary battery and electric device containing the same

Abstract

The application provides a carbonaceous material and a preparation method thereof, and a secondary battery and an electric device containing the carbonaceous material. After the carbonaceous material is subjected to an adsorption test using water vapor under a constant temperature and humidity condition of 25 DEG C and 100% RH and is allowed to stand for 100 h, the adsorbed mass of the water vapor is denoted as A, the initial mass of the carbonaceous material is denoted as B, and 0.13 <= A / B <= 0.50. The application can simultaneously improve the capacity and the first coulomb efficiency of the carbonaceous material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of batteries, and particularly relates to a carbonaceous material and a preparation method thereof, and a secondary battery and an electric device containing the same. BACKGROUND

[0002] In recent years, secondary batteries are widely applied in energy storage power systems such as hydraulic, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the application and promotion of secondary batteries, their energy density, service life and rate performance are attracting more and more attention. Graphite is the most commonly used negative active material for secondary batteries, but its theoretical specific capacity is only 372 mAh / g, and the space for improving the energy density is very limited; at the same time, the interlayer spacing of graphite is small, and the rate performance is also limited. As a new type of negative active material, hard carbon can realize the rapid intercalation and deintercalation of active ions during the charging and discharging process of secondary batteries, so its development prospect is very broad. However, the capacity and the first coulombic efficiency of hard carbon are low, which limits the improvement of the energy density, service life and rate performance of secondary batteries. SUMMARY

[0003] The purpose of the present application is to provide a carbonaceous material and a preparation method thereof, and a secondary battery and an electric device containing the same, aiming to simultaneously improve the capacity and the first coulombic efficiency of the carbonaceous material.

[0004] The first aspect of the present application provides a carbonaceous material, wherein the adsorption mass of water vapor is denoted as A, and the initial mass of the carbonaceous material is denoted as B after the adsorption test under the condition of constant temperature and humidity at 25°C and 100% RH for 100 h, and 0.13≤A / B≤0.50.

[0005] The inventors have found in their research that when A / B is between 0.13 and 0.50, the carbonaceous material has high structural stability and a large number of active ion storage spaces, and these spaces are also conducive to the reversible deintercalation and intercalation of active ions, so that the carbonaceous material of the present application can have both high capacity and high first coulombic efficiency, and the secondary battery can also have high energy density, long service life and good rate performance.

[0006] In any embodiment of the present application, 0.15≤A / B≤0.50, and optionally 0.30≤A / B≤0.496. This is conducive to further improving the capacity and the first coulombic efficiency of the carbonaceous material.

[0007] In any embodiment of the present application, the true density p of the carbonaceous material is 1.0 g / cm 3 -1.6 g / cm 3 , and optionally 1.05 g / cm3 -1.45g / cm 3 When the true density of the carbonaceous material also satisfies the above specific range, it is helpful to further improve the gravimetric capacity and the first coulombic efficiency of the carbonaceous material.

[0008] In any embodiment of the present application, the carbonaceous material comprises a plurality of nanopore structures, and optionally, the carbonaceous material comprises a plurality of pore structures with a pore size of less than 10 nm.

[0009] In any embodiment of the present application, in the Raman spectrum of the carbonaceous material, I d / I g is 1.0-1.3, and optionally 1.05-1.15, I d represents the intensity of the d peak with a Raman shift in the range of 1350±50 cm -1 -1.450 cm-1, I g represents the intensity of the g peak with a Raman shift in the range of 1580±50 cm -1 -1.650 cm-1. At this time, the order degree of the carbonaceous material structure is moderate, so that the carbonaceous material has higher capacity and higher first coulombic efficiency, and also has good rate performance.

[0010] In any embodiment of the present application, the interlayer spacing of the (002) crystal plane of the carbonaceous material is ≥0.37 nm, and optionally 0.37 nm-0.42 nm.

[0011] In any embodiment of the present application, in the X-ray diffraction spectrum of the carbonaceous material, the (002) crystal plane peak corresponds to a 2θ value of 22° to 24°.

[0012] In any embodiment of the present application, the volume particle size Dv50 of the carbonaceous material is 3 μm-7 μm, and optionally 4 μm-6 μm.

[0013] In any embodiment of the present application, the volume particle size Dv90 of the carbonaceous material is 8 μm-15 μm, and optionally 9 μm-12 μm.

[0014] When the volume particle size Dv50 and / or Dv90 of the carbonaceous material is in a suitable range, it is beneficial to improve the active ion and electron transport performance, so as to further improve the rate performance of the secondary battery.

[0015] In any embodiment of the present application, the specific surface area of the carbonaceous material is 0.1 m 2 / g-10 m 2 / g, and optionally 1 m 2 / g-5 m 2 / g. When the specific surface area of ​​carbonaceous materials is within a suitable range, carbonaceous materials can simultaneously possess higher capacity and first coulombic efficiency, as well as better rate performance.

[0016] In any embodiment of this application, the compacted density of the carbonaceous material powder under a force of 50,000 N is 0.90 g / cm³. 3 -1.05g / cm 3 The option is 0.93g / cm³. 3 -1.02g / cm 3 When the compaction density of carbonaceous material powder is within a suitable range, the compaction density of the negative electrode sheet can be increased, thereby improving the energy density of the secondary battery.

[0017] In any embodiment of this application, the tap density of the carbonaceous material is 0.80 g / cm³. 3 -0.95g / cm 3 0.85g / cm³ is an optional value. 3 -0.90g / cm 3 When the tap density of carbonaceous materials is within a suitable range, the tap density of the negative electrode sheet can be increased, thereby improving the energy density of the secondary battery.

[0018] A second aspect of this application provides a method for preparing a carbonaceous material, comprising the following steps:

[0019] S10, Providing raw materials: The raw materials are organic carbon sources;

[0020] S20, Crushing process: Crushing the raw material to the required particle size;

[0021] S30, Washing and impurity removal treatment: The crushed raw material obtained in S20 is subjected to washing and impurity removal treatment, the washing and impurity removal treatment process includes at least an acidic solution washing step and an alkaline solution washing step;

[0022] S40, Carbonization treatment: The washed and purified raw material obtained in S30 is placed in a kiln, a protective gas containing hydrogen is introduced, and the furnace pressure is controlled at ≤-2kPa. Then, the temperature is increased to the target temperature T1 at a rate of ≤1℃ / min, and then held at the target temperature T1 for a target time t1. After the treatment, carbonaceous material is obtained. The carbonaceous material is subjected to water vapor adsorption test under constant temperature and humidity conditions of 25℃ and 100%RH. After standing for 100h, the adsorbed mass of water vapor is recorded as A, and the initial mass of the carbonaceous material is recorded as B. 0.13≤A / B≤0.50.

[0023] The carbonaceous material obtained by the preparation method provided in this application can achieve both high capacity and first coulombic efficiency, thereby enabling the secondary battery to have high energy density, long service life and good rate performance.

[0024] In any embodiment of this application, in S20, the crushing includes ball milling or air jet milling.

[0025] In any embodiment of this application, in S30, the washing and impurity removal process sequentially includes the following steps: acidic solution washing, water washing, alkaline solution washing, water washing, and drying; or, in S30, the washing and impurity removal process sequentially includes the following steps: alkaline solution washing, water washing, acidic solution washing, water washing, and drying.

[0026] In any embodiment of this application, the H of the acidic solution + The concentration is 0.1 mol / L to 6 mol / L, and can be selected as 1 mol / L to 6 mol / L.

[0027] In any embodiment of this application, the washing temperature of the acidic solution is 10℃-95℃, and can be selected as 30℃-95℃.

[0028] In any embodiment of this application, the washing time of the acidic solution is 1h-24h, and can be selected as 10h-24h.

[0029] In any embodiment of this application, the solute of the acidic solution includes one or more of hydrochloric acid, nitric acid, sulfuric acid and perchloric acid, and the solvent includes water.

[0030] By adjusting the H+ of the acidic solution + When one or more of the following factors—concentration, washing temperature, washing time, and type of solute—are within the above range, it is beneficial to achieve thorough washing and better remove metal impurities.

[0031] In any embodiment of this application, the OH- of the alkaline solution - The concentration is 0.1 mol / L to 6 mol / L, and can be selected as 1 mol / L to 6 mol / L.

[0032] In any embodiment of this application, the washing temperature of the alkaline solution is 10℃-95℃, and can be selected as 30℃-95℃.

[0033] In any embodiment of this application, the washing time of the alkaline solution is 1h-24h, and can be selected as 10h-24h.

[0034] In any embodiment of this application, the solute of the alkaline solution includes NaOH, KOH, or a combination thereof, and the solvent includes water.

[0035] By adjusting the OH- of the alkaline solution - When one or more of the following factors—concentration, washing temperature, washing time, and type of solute—are within the above range, it is beneficial to achieve thorough washing.

[0036] In any embodiment of this application, in S40, the temperature T1 is 1000℃-1600℃, optionally 1150℃-1500℃. When the temperature T1 is within the above range, the carbonaceous material exhibits good pore-closing effect, with small pore size and ample active ion storage space, thus resulting in a high capacity. Simultaneously, the proportion of the electrolyte wetting area inside the carbonaceous material is low, leading to lower consumption of active ions during SEI film formation. Consequently, the initial irreversible capacity loss of the carbonaceous material is low, and the initial coulombic efficiency is high.

[0037] In any embodiment of this application, in S40, the time t1 is ≥1h, and can be selected as 10h-24h. When the heat preservation time t1 is within the above range, the heteroatom content of the carbonaceous material can be effectively reduced, giving the carbonaceous material a higher initial coulombic efficiency.

[0038] In any embodiment of this application, in S40, the heating rate is 0.05℃ / min-1℃ / min, optionally 0.1℃ / min-1℃ / min. This can improve production efficiency and reduce energy waste.

[0039] In any embodiment of this application, in S40, the protective gas comprises a mixture of hydrogen and an inert gas, and the volume concentration of the hydrogen is greater than 0 and less than or equal to 5%, optionally 1%-5%. The volume concentration of hydrogen is ≤5%, mainly for safety reasons.

[0040] In any embodiment of this application, in S40, the furnace pressure is -5 kPa to -2 kPa, optionally -5 kPa to -3 kPa. This helps to ensure safe production.

[0041] In any embodiment of this application, in S10, the organic carbon source includes one or more of biomass materials and thermoplastic resin materials.

[0042] In any embodiment of this application, the biomass material includes one or more of energy crops and biomass waste.

[0043] In any embodiment of this application, the thermoplastic resin material includes one or more of phenolic resin, acrylic resin, polyvinyl chloride, polycarbonate, epoxy resin, polyoxymethylene, coumarone resin and petroleum resin.

[0044] A third aspect of this application provides a secondary battery comprising a negative electrode, wherein the negative electrode comprises the carbonaceous material of the first aspect of this application or the carbonaceous material prepared by the method of the second aspect of this application.

[0045] The fourth aspect of this application provides an electrical device that includes the secondary battery of the third aspect of this application.

[0046] The carbonaceous material provided in this application achieves a balance between high capacity and initial coulombic efficiency, enabling the secondary battery to simultaneously possess high energy density, long service life, and good rate performance. The electrical device of this application includes the secondary battery provided in this application, and therefore possesses at least the same advantages as the aforementioned secondary battery. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0048] Figure 1 This is a schematic diagram of one embodiment of the battery cell of this application.

[0049] Figure 2 This is an exploded view of one embodiment of the battery cell of this application.

[0050] Figure 3 This is a schematic diagram of one embodiment of the battery module of this application.

[0051] Figure 4 This is a schematic diagram of one embodiment of the battery pack of this application.

[0052] Figure 5 yes Figure 4 An exploded view of an embodiment of the battery pack shown.

[0053] Figure 6 This is a schematic diagram of one embodiment of an electrical device that uses a secondary battery as a power source, as described in this application.

[0054] Figure 7 and Figure 8 This is a scanning electron microscope image of the carbonaceous material provided in this application.

[0055] The accompanying drawings are not necessarily drawn to scale. The reference numerals are explained as follows: 1 Battery pack, 2 Upper casing, 3 Lower casing, 4 Battery module, 5 Individual battery cell, 51 Housing, 52 Electrode assembly, 53 Cover plate. Detailed Implementation

[0056] The carbonaceous material and its preparation method, as well as embodiments of secondary batteries and power-consuming devices containing the same, are disclosed in detail below with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0057] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0058] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0059] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0060] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0061] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0062] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0063] Unless otherwise specified, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0064] Unless otherwise specified, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in this application.

[0065] Unless otherwise specified, in this application, the term "active ion" refers to ions that can be inserted and extracted back and forth between the positive and negative electrodes of a secondary battery, including but not limited to lithium ions, sodium ions, etc.

[0066] In this application, the terms "multiple" or "various" refer to two or more kinds of things.

[0067] According to the International Union of Pure and Applied Chemistry (IUPAC), micropores are pores with a diameter < 2 nm, mesopores are pores with a diameter between 2 nm and 50 nm, and macropores are pores with a diameter > 50 nm.

[0068] In the context of this application, the term "micropore" refers to a pore with a diameter < 2 nm; the term "mesopore" refers to a pore with a diameter of 2 nm to 50 nm; and the term "macropore" refers to a pore with a diameter > 50 nm.

[0069] In the context of this application, the term "small mesopore" refers to a pore with a diameter of 2nm-10nm, and the term "large mesopore" refers to a pore with a diameter greater than 10nm and less than or equal to 50nm.

[0070] With the application and promotion of rechargeable batteries, their energy density, lifespan, and rate performance have received increasing attention. The performance of the negative electrode active material largely determines the energy density, lifespan, and safety of the rechargeable battery. Graphite (including natural and artificial graphite) is the most commonly used negative electrode active material in rechargeable batteries, but its theoretical specific capacity is only 372 mAh / g, leaving very limited room for energy density improvement. At the same time, the small interlayer spacing of graphite also limits the improvement of rate performance, making it unable to meet the actual needs of high-rate rechargeable batteries.

[0071] Compared to graphite, hard carbon has a larger interlayer spacing, which facilitates the rapid insertion and extraction of active ions. This results in superior low-temperature performance, power performance, and safety performance in rechargeable batteries, giving hard carbon a unique advantage, especially in the field of power batteries. However, most commercially available hard carbon batteries are currently low-capacity types, with low capacity and initial coulombic efficiency. For example, the capacity is typically between 200 mAh / g and 300 mAh / g, and the initial coulombic efficiency is usually below 85%, which severely limits their practical applications.

[0072] Therefore, how to simultaneously improve the capacity and first coulomb efficiency of hard carbon remains a pressing technical challenge.

[0073] In view of this, the first aspect of the present application provides a carbonaceous material that combines high capacity and first coulombic efficiency, and enables secondary batteries to simultaneously have high energy density, long service life and good rate performance.

[0074] Carbonaceous material

[0075] The carbonaceous material provided in this application was subjected to an adsorption test using water vapor under constant temperature and humidity conditions of 25℃ and 100%RH. After standing for 100 hours, the adsorbed mass of water vapor was recorded as A, and the initial mass of the carbonaceous material was recorded as B. 0.13≤A / B≤0.50.

[0076] The adsorption test was conducted under the following conditions: In a constant temperature and humidity chamber at 25°C and 100% RH, a carbonaceous material of mass B was uniformly placed in a petri dish with a diameter of 10 cm and the stacking thickness of the carbonaceous material was ≤0.2 cm. After standing for 100 h, the increased mass of the carbonaceous material was weighed and recorded as the adsorbed mass of water vapor A.

[0077] RH (Relative Humidity) refers to the percentage of the partial pressure of water vapor in the air to the saturated vapor pressure of water at the same temperature.

[0078] Compared to currently commercially available hard carbon, the carbonaceous material provided in this application achieves a balance between high capacity and initial coulombic efficiency. Although the mechanism is not yet clear, the inventors speculate that one possible reason is that the carbonaceous material provided in this application has a unique pore structure that facilitates the insertion, storage, and extraction of active ions, thereby enabling the carbonaceous material provided in this application to achieve a balance between high capacity and initial coulombic efficiency.

[0079] During the research process, the inventors of this application discovered that, under constant temperature and humidity conditions of 25°C and 100%RH, the mass of water vapor adsorbed by a unit mass of carbonaceous material within 100 hours (A / B) can reflect the spatial content of carbonaceous material suitable for the storage and reversible extraction and insertion of active ions.

[0080] When A / B is less than 0.13, the adsorption capacity of carbonaceous materials for water vapor is low. It is believed that there is very little space inside the carbonaceous material that is suitable for the storage and reversible extraction and insertion of active ions. As a result, the capacity and initial coulombic efficiency of carbonaceous materials are both low.

[0081] When the A / B ratio is greater than 0.50, the carbonaceous material exhibits a high adsorption capacity for water vapor. However, the inventors discovered during their research that at this ratio, a large amount of water vapor is adsorbed into the interlayer structure of the carbonaceous material, which cannot effectively store active ions. Furthermore, the excellent pore-closing effect of the carbonaceous material may also prevent active ions from easily embedding into its porous structure. Consequently, when A / B is greater than 0.50, the internal space of the carbonaceous material is also limited, resulting in a small amount of space suitable for the storage and reversible extraction and embedding of active ions, leading to low capacity and initial coulombic efficiency.

[0082] The inventors also discovered in their research that when A / B is between 0.13 and 0.50, the carbonaceous material exhibits high structural stability and possesses ample active ion storage space. This space also facilitates the reversible extraction and insertion of active ions. Therefore, the carbonaceous material of this application can achieve both high capacity and initial coulombic efficiency, enabling the secondary battery to simultaneously possess high energy density, long lifespan, and good rate performance. For example, A / B can be a range consisting of 0.14, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, or any of the above values. In some embodiments, optionally, 0.15≤A / B≤0.50, 0.20≤A / B≤0.50, 0.25≤A / B≤0.498, 0.30≤A / B≤0.496, 0.35≤A / B≤0.496, and 0.40≤A / B≤0.496. This is beneficial for further improving the capacity and initial coulombic efficiency of carbonaceous materials.

[0083] In some embodiments, the carbonaceous material comprises multiple nanoporous structures. Optionally, the carbonaceous material comprises multiple pore structures with pore sizes less than 10 nm. In some embodiments, the carbonaceous material may further comprise one or more pore structures with pore sizes greater than 10 nm.

[0084] Further research by the inventors revealed that by ensuring the above-mentioned parameter A / B of the carbonaceous material satisfies 0.13≤A / B≤0.50, and by further adjusting the true density of the carbonaceous material within a suitable range, it is possible to more accurately reflect the spatial content of the carbonaceous material suitable for the storage and reversible extraction and insertion of active ions.

[0085] During true density testing, the space that the calibration liquid (e.g., n-butanol) can penetrate is less than the actual space present in the carbonaceous material. These unexplored spaces may contain active ions. The aforementioned parameter A / B reflects the amount of space in the carbonaceous material suitable for the storage and reversible extraction and insertion of active ions. However, carbonaceous materials include not only porous structures but also interlayer structures. These interlayer structures cannot effectively store active ions, and the calibration liquid does not penetrate them, while water vapor can be adsorbed into them. Therefore, the space suitable for the storage and reversible extraction and insertion of active ions, as reflected by the aforementioned parameter A / B, may include some spaces that cannot effectively store active ions. Therefore, by simultaneously adjusting the aforementioned parameters A / B and true density of the carbonaceous material within appropriate ranges, the amount of space suitable for the storage and reversible extraction and insertion of active ions in the carbonaceous material can be more accurately reflected.

[0086] In some embodiments, the true density ρ of the carbonaceous material is 1.0 g / cm³. 3 -1.6g / cm 3For example, it can be 1.0 g / cm³. 3 1.05g / cm 3 1.1g / cm 3 1.15g / cm 3 1.2g / cm 3 1.25g / cm 3 1.3g / cm 3 1.35g / cm 3 1.4g / cm 3 1.45g / cm 3 1.5g / cm 3 1.55g / cm 3 Or any range of the above values. Optionally, the true density ρ of the carbonaceous material is 1.05 g / cm³. 3 -1.45g / cm 3 1.10 g / cm 3 -1.40g / cm 3 Further research by the inventors revealed that when the true density of carbonaceous materials still meets the aforementioned specific range, it helps to further improve the specific capacity and first coulombic efficiency of carbonaceous materials.

[0087] When the true density of carbonaceous materials is too high or too low, it is not conducive to improving the specific capacity and initial coulombic efficiency. When the true density of carbonaceous materials is too low, there is less space for the calibration liquid (e.g., n-butanol) to enter. This may be because the carbonaceous material has too good a pore-closing effect, making it difficult for active ions to embed in the pore structure. It may also be due to the presence of more interlayer structures in the carbonaceous material that are not suitable for storing active ions.

[0088] When the true density of carbonaceous materials is too high, the calibration liquid (e.g., n-butanol) can easily wet the interior of the carbonaceous material particles. It is believed that the carbonaceous material has poor pore-closing effect and abundant macroporous and / or macroporous structures. As a result, the microporous and / or small mesoporous structures are easily exposed to the electrolyte, which reduces the storage space for active ions and thus reduces the specific capacity and initial coulombic efficiency of the carbonaceous material.

[0089] In this application, the true density of carbonaceous materials has a meaning known in the art and can be determined using instruments and methods known in the art. For example, the Archimedes impregnation volume displacement method can be used for testing, and n-butanol can be used as the calibration liquid. A powder true density meter can be used as the testing instrument.

[0090] In some embodiments, the carbonaceous material may have a regular or irregular morphology; for example, the morphology of the carbonaceous material may be an irregular polygonal shape.

[0091] In some embodiments, the C content in the carbonaceous material may be ≥95wt%, and may be 95wt%-98wt%.

[0092] In some embodiments, the oxygen content in the carbonaceous material may be ≤5wt%, and optionally 1wt%-5wt%. Oxygen heteroatoms cannot reversibly intercalate or deintercalate with active ions after binding. The carbonaceous material provided in this application has a low content of oxygen heteroatoms, thereby reducing the irreversible consumption of active ions.

[0093] In some embodiments, the hydrogen content in the carbonaceous material may be ≤0.3wt%, and may be 0.1wt%-0.2wt%.

[0094] In some embodiments, the nitrogen content in the carbonaceous material may be ≤0.3wt%, and may be 0.01wt%-0.1wt%.

[0095] In some embodiments, the total content of C, O, H and N elements in the carbonaceous material may be ≥99wt%, and may be 99wt%-99.5wt%.

[0096] In some embodiments, the sulfur content in the carbonaceous material may be ≤0.2wt%, and may be 0.01wt%-0.1wt%.

[0097] In some embodiments, the Na content in the carbonaceous material may be ≤0.014wt%, and optionally ≤0.005wt%.

[0098] In some embodiments, in the Raman spectrum of the carbonaceous material, I d / I g The value is 1.0-1.3, I d This indicates that the Raman displacement is within 1350±50cm. -1 The d-peak intensity within the range, I g This indicates that the Raman displacement is within 1580±50cm. -1 The intensity of the g peak within the range. For example, I d / I g It can be a range consisting of any values ​​of 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, or higher. Optionally, I d / I g It can be 1.05-1.15.

[0099] The Raman spectra of carbonaceous materials can be measured using a Raman spectrometer. During the test, the d-peak and g-peak intensities at 100 points are acquired, and the Ig at these 100 points is calculated. d / I g Remove the largest and smallest 30 I's. d / I g 40 I's remaining d / I g The average value is used as the I of carbonaceous materials d / I g The testing instrument can be a Horiba LabRAM HR800 Raman spectrometer. The testing conditions can be: excitation wavelength 532 nm, grating 600 lines, objective lens 50x, integration time 10 s, cumulative count 3, area scan.

[0100] The d-peak originates from lattice defects in carbon atoms, while the g-peak originates from in-plane vibrations of sp2 carbon atoms. In carbonaceous materials, the intensity of the d-peak is related to the number of defects in the structure, and the intensity of the g-peak is related to the number of graphite crystallites. Therefore, I d / I g It can characterize the degree of order in the structure of carbonaceous materials. d / I g The smaller the value, the higher the orderliness of the carbonaceous material structure, the higher the integrity of the carbon plane, and the higher the initial coulombic efficiency of the carbonaceous material, but the capacity decreases and the rate performance deteriorates. The carbonaceous material of this application satisfies I... d / I g The value is 1.0-1.3. At this point, the degree of order in the carbonaceous material structure is moderate, resulting in higher capacity and higher first coulombic efficiency, while also exhibiting good rate performance.

[0101] In some embodiments, the interlayer spacing of the (002) crystal plane of the carbonaceous material is ≥0.37 nm, and can be selected as 0.37 nm-0.42 nm.

[0102] In some embodiments, in the X-ray diffraction spectrum of the carbonaceous material, the 2θ value corresponding to the (002) crystal plane peak is between 22° and 24°.

[0103] In this application, the interlayer spacing of the (002) crystal plane of the carbonaceous material can be measured using an X-ray diffractometer, referring to JIS K 0131-1996 and JB / T4220-2011. The measuring instrument can be a Bruker D8 Discover X-ray diffractometer.

[0104] In some embodiments, the volumetric particle size Dv50 of the carbonaceous material is 3μm-7μm, and optionally 4μm-6μm.

[0105] In some embodiments, the volumetric particle size Dv90 of the carbonaceous material is 8μm-15μm, and optionally 9μm-12μm.

[0106] In some embodiments, the volumetric particle size Dv50 of the carbonaceous material is 3 μm-7 μm and the volumetric particle size Dv90 is 8 μm-15 μm. Optionally, the volumetric particle size Dv50 of the carbonaceous material is 4 μm-6 μm and the volumetric particle size Dv90 is 9 μm-12 μm.

[0107] When the volumetric particle size Dv50 and / or Dv90 of carbonaceous materials are within a suitable range, it is beneficial to improve the active ion and electron transport performance, thereby further improving the rate performance of secondary batteries.

[0108] In this application, the volumetric particle sizes Dv50 and Dv90 of carbonaceous materials have meanings known in the art, representing the particle size corresponding to a cumulative volumetric distribution percentage of 50% and 90%, respectively, and can be determined using instruments and methods known in the art. For example, they can be conveniently determined using a laser particle size analyzer, referring to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method. The testing instrument can be a Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK.

[0109] In some embodiments, the specific surface area of ​​the carbonaceous material is 0.1 m². 2 / g-10m 2 / g, optional 1m 2 / g-5m 2 / g. A lower specific surface area of ​​carbonaceous materials helps reduce their surface activity, decreasing the consumption of active ions during SEI film formation and thus improving the initial coulombic efficiency of both the carbonaceous material and the secondary battery. Conversely, a higher specific surface area of ​​carbonaceous materials facilitates faster active ion transport, thereby enhancing the rate performance of the secondary battery. Therefore, when the specific surface area of ​​carbonaceous materials is within a suitable range, they can simultaneously exhibit higher capacity and initial coulombic efficiency, along with better rate performance. Furthermore, when the specific surface area of ​​carbonaceous materials is within a suitable range, the carbonaceous material and binder also possess strong bonding forces, thereby improving the cohesion and adhesion of the negative electrode, reducing the volume expansion of the negative electrode during cycling, and resulting in better cycle performance of the secondary battery.

[0110] In this application, the specific surface area of ​​carbonaceous materials has a meaning known in the art and can be measured using instruments and methods known in the art. For example, it can be measured using the nitrogen adsorption specific surface area analysis method according to GB / T 19587-2017 and calculated using the BET (Brunauer Emmett Teller) method. The nitrogen adsorption specific surface area analysis can be performed using the ASAP 3020 surface area and pore size analyzer from Micromeritics, Inc., USA.

[0111] In some embodiments, the compacted density of the carbonaceous material powder under a force of 50,000 N is 0.90 g / cm³. 3 -1.05g / cm 3 The option is 0.93g / cm³. 3 -1.02g / cm 3 When the compaction density of carbonaceous material powder is within a suitable range, the compaction density of the negative electrode sheet can be increased, thereby improving the energy density of the secondary battery.

[0112] In this application, the compacted density of carbonaceous material powder has a meaning known in the art and can be determined using instruments and methods known in the art. For example, it can be determined using an electronic pressure testing machine (e.g., UTM7305 type) according to GB / T24533-2009. An exemplary test method is as follows: Weigh 1g of carbonaceous material powder and add it to a container with a bottom area of ​​1.327cm². 2 In the mold, the pressure is increased to 5000 kg (equivalent to 50000 N), held for 30 seconds, then depressurized and held for 10 seconds. The compaction density of the carbonaceous material under a force of 50000 N is then recorded and calculated.

[0113] In some embodiments, the tap density of the carbonaceous material is 0.80 g / cm³. 3 -0.95g / cm 3 0.85g / cm³ is an optional value. 3 -0.90g / cm 3 When the tap density of carbonaceous materials is within a suitable range, the tap density of the negative electrode sheet can be increased, thereby improving the energy density of the secondary battery.

[0114] In this application, the tap density of carbonaceous materials has a meaning known in the art and can be determined using instruments and methods known in the art. For example, it can be determined using a powder tap density tester according to GB / T 5162-2006. The testing instrument can be the Dandong Baite BT-301.

[0115] Method for producing a carbonaceous material

[0116] The second aspect of this application provides a method for preparing a carbonaceous material, comprising the following steps: S10, providing raw materials: the raw materials are organic carbon sources; S20, crushing treatment: crushing the raw materials to the required particle size; S30, washing and impurity removal treatment: washing and impurity removal treatment of the crushed raw materials obtained in S20, wherein the washing and impurity removal treatment process includes at least an acidic solution washing step and an alkaline solution washing step; S40, carbonization treatment: placing the washed and impurity removed raw materials obtained in S30 in a kiln, introducing a protective gas containing hydrogen, and controlling the furnace pressure to ≤-2kPa, then heating to a target temperature T1 at a rate of ≤1℃ / min, and then holding at the target temperature T1 for a target time t1, thereby obtaining the carbonaceous material, wherein the carbonaceous material is subjected to an adsorption test using water vapor under constant temperature and humidity conditions of 25℃ and 100%RH, and after standing for 100h, the adsorbed mass of water vapor is recorded as A, the initial mass of the carbonaceous material is recorded as B, and 0.13≤A / B≤0.50.

[0117] The method for preparing carbonaceous materials in this application includes a crushing process, a washing and impurity removal process, and a carbonization process.

[0118] Crushing can reduce the particle size of raw materials, thereby helping to obtain carbonaceous materials of the desired size. In some embodiments, the volumetric particle size Dv50 of the crushed particles is 3μm-7μm, optionally 4μm-6μm. In some embodiments, the volumetric particle size Dv90 of the crushed particles is 8μm-15μm, optionally 9μm-12μm. In some embodiments, the volumetric particle size Dv50 of the crushed particles is 3μm-7μm and the volumetric particle size Dv90 is 8μm-15μm; optionally, the volumetric particle size Dv50 of the crushed particles is 4μm-6μm and the volumetric particle size Dv90 is 9μm-12μm.

[0119] Washing and impurity removal processes can remove inorganic and water-soluble impurities from the raw materials, preventing metal impurities from being reduced to elemental metals and then agglomerating during subsequent carbonization. This is because the agglomeration of elemental metals leads to the collapse of the carbon framework structure, especially the microporous and / or small mesoporous structures, resulting in a reduction in the active ion storage space and capacity of the obtained carbonaceous material. Simultaneously, metal impurities also possess catalytic activity, intensifying the decomposition of the carbon framework structure during thermal decomposition, causing the pore structure to tend towards larger mesoporous and / or macroporous structures. This results in an increased proportion of the electrolyte wetting area within the obtained carbonaceous material, increased consumption of active ions during SEI film formation, increased initial irreversible capacity loss, and decreased initial coulombic efficiency. The washing and impurity removal process includes at least acidic and alkaline solution washing steps. The acidic solution is mainly used to remove metal impurities from the raw materials, while the alkaline solution is mainly used to remove Si-containing impurities that cannot react with acid, thus ensuring thorough impurity removal.

[0120] The crushing process must be performed before the washing and impurity removal process. This ensures that as much surface area as possible is exposed during washing and impurity removal, facilitating sufficient contact between the particles and the washing liquid and improving the impurity removal effect. If the crushing process is performed after the washing and impurity removal process, the washing liquid may not be able to penetrate the bulk phase of large raw material particles. Consequently, deeply encapsulated impurities in the bulk phase of large raw material particles cannot be removed, resulting in poor impurity removal. Consequently, during the subsequent carbonization process, the unremoved metal impurities will be reduced to elemental metals and then agglomerate. The agglomeration of elemental metals leads to the collapse of the carbon skeleton structure, especially the collapse of microporous and / or small mesoporous structures. This results in a reduction of the active ion storage space and a decrease in capacity of the obtained carbonaceous material. At the same time, the metal impurities also have catalytic activity, which will intensify the decomposition of the carbon skeleton structure during thermal decomposition, causing the pore structure to tend to form larger mesoporous and / or macroporous structures. This leads to an increase in the proportion of the electrolyte wetting area inside the obtained carbonaceous material, an increase in the consumption of active ions by the SEI film formation, an increase in the initial irreversible capacity loss, and a decrease in the initial coulombic efficiency.

[0121] During carbonization, the temperature is increased at a rate of ≤1℃ / min. If the heating rate is too fast, the gaseous small molecules released during the thermal decomposition of the raw material cannot escape from the particulate phase to the surface and then conduct to the furnace for discharge with the help of the furnace's protective gas. Instead, these gaseous small molecules become trapped in the particulate phase and are converted into carbon through further thermal decomposition. This blocks the pore structure, resulting in a reduction in the active ion storage space and capacity of the obtained carbonaceous material. Furthermore, if the heating rate is too fast, the true density of carbonaceous material of the same size increases, and the obstructed pore structure makes it more difficult for active ions to escape, thus reducing the initial coulombic efficiency.

[0122] The protective gas used in carbonization contains hydrogen, which has a reducing effect, reducing the formation of oxygen-containing functional groups on the surface of carbonaceous materials. This results in fewer heteroatom (e.g., oxygen heteroatoms) defects in the final carbonaceous material, increasing the initial coulombic efficiency. When the protective gas does not contain hydrogen, some oxygen-containing functional groups on the surface of the carbonaceous material cannot be effectively reduced, leading to an excessive number of oxygen heteroatoms in the final carbonaceous material. These oxygen heteroatoms cannot reversibly intercalate or deintercalate with active ions, thus reducing the initial coulombic efficiency of the carbonaceous material. Simultaneously, a large number of oxygen-containing functional groups remain on the surface of the carbonaceous material. These oxygen-containing functional groups form hydrogen bonds with water molecules, causing numerous water molecule clusters to clog the surface of the carbonaceous material, hindering the intercalation of active ions, and consequently reducing the specific capacity of the carbonaceous material.

[0123] The inventors of this application also unexpectedly discovered during their research that the furnace pressure affects the performance of the final carbonaceous material. If the furnace pressure is too high, the gaseous small molecules released during the pyrolysis of the raw materials cannot escape from the particulate phase to the outside in time. Instead, these gaseous small molecules become trapped in the particulate phase and are converted into carbon through further pyrolysis, thus blocking the pore structure. This results in a reduction in the active ion storage space and a decrease in capacity of the obtained carbonaceous material. Furthermore, if the furnace pressure is too high, the true density of carbonaceous material of the same size increases, and the obstructed pore structure of the carbonaceous material makes it more difficult for active ions to escape, thereby reducing the initial coulombic efficiency.

[0124] Therefore, the carbonaceous material obtained by the preparation method provided in this application can achieve both high capacity and first coulombic efficiency, thereby enabling the secondary battery to have high energy density, long service life and good rate performance.

[0125] The preparation method of the second aspect of this application can prepare carbonaceous materials according to any embodiment of the first aspect of this application. The preparation method of carbonaceous materials provided by this application has a simple process and is suitable for commercial production. The preparation method of carbonaceous materials provided by this application does not require the addition of additional conductive agents or other additives, thereby the carbonaceous materials obtained by the preparation method provided by this application have a lower heteroatom content.

[0126] In this application, "organic carbon source" refers to a general term for a class of substances rich in carbon and capable of forming carbonaceous materials. In some embodiments, in S10, the organic carbon source may include one or more of biomass materials and thermoplastic resin materials; optionally, the organic carbon source includes biomass materials. In some embodiments, the organic carbon source may also include only biomass materials.

[0127] Biomass materials may be materials known in the art suitable for preparing carbonaceous materials. In some embodiments, the biomass material may include one or more of energy crops and biomass waste. For example, the biomass material includes, but is not limited to, one or more of wood, straw, bamboo, bark, and nutshells.

[0128] In some embodiments, the thermoplastic resin material may include one or more of phenolic resin, acrylic resin, polyvinyl chloride, polycarbonate, epoxy resin, polyoxymethylene, coumarone resin and petroleum resin.

[0129] In some embodiments, in S20, the crushing may employ a process known in the art suitable for crushing in the preparation of carbonaceous materials, such as ball milling or air jet milling.

[0130] The order of acidic solution washing and alkaline solution washing is not particularly limited. In some embodiments, in S30, the washing and impurity removal process sequentially includes the following steps: acidic solution washing, water washing, alkaline solution washing, water washing, and drying. In some embodiments, in S30, the washing and impurity removal process sequentially includes the following steps: alkaline solution washing, water washing, acidic solution washing, water washing, and drying. Deionized water can be used for water washing, and the number of water washings can be one or more, until the pH of the filtrate is neutral (i.e., pH 7 ± 0.5), at which point the water washing process is considered complete. Drying can be by forced air drying or vacuum drying, until the mass change rate of the material after a 2-hour interval is <0.1 wt%, at which point the drying process is considered complete.

[0131] This application does not impose any particular restrictions on parameters such as the type and concentration of solute, washing temperature, and washing time of acidic and alkaline solutions, as long as the impurities are sufficiently removed.

[0132] In some embodiments, in S30, the H of the acidic solution + The concentration is 0.1 mol / L to 6 mol / L, and can be selected as 1 mol / L to 6 mol / L.

[0133] In some embodiments, in S30, the washing temperature of the acidic solution is 10°C-95°C, optionally 30°C-95°C.

[0134] In some embodiments, in S30, the washing time of the acidic solution is 1h-24h, optionally 10h-24h.

[0135] In some embodiments, in S30, the solute of the acidic solution includes one or more of hydrochloric acid, nitric acid, sulfuric acid, and perchloric acid, and the solvent includes water. This ensures the thorough removal of metallic impurities while preventing the introduction of other impurity elements.

[0136] By adjusting the H+ of the acidic solution + When one or more of the following factors—concentration, washing temperature, washing time, and type of solute—are within the above range, it is beneficial to achieve thorough washing and better remove metal impurities.

[0137] In some embodiments, in S30, the OH- of the alkaline solution - The concentration is 0.1 mol / L to 6 mol / L, and can be selected as 1 mol / L to 6 mol / L.

[0138] In some embodiments, in S30, the washing temperature of the alkaline solution is 10°C-95°C, optionally 30°C-95°C.

[0139] In some embodiments, in S30, the washing time of the alkaline solution is 1h-24h, optionally 10h-24h.

[0140] In some embodiments, in S30, the solute of the alkaline solution includes NaOH, KOH, or a combination thereof, and the solvent includes water. This ensures, on the one hand, the complete removal of impurities such as Si, and on the other hand, prevents the introduction of other impurity elements.

[0141] By adjusting the OH- of the alkaline solution - When one or more of the following factors—concentration, washing temperature, washing time, and type of solute—are within the above range, it is beneficial to achieve thorough washing.

[0142] In some embodiments, in S40, the temperature T1 is 1000℃-1600℃, for example, it can be a range of 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃, 1500℃, 1550℃, 1600℃ or any higher. Optionally, the temperature T1 is 1150℃-1500℃.

[0143] When the temperature T1 is within the above range, the carbonaceous material has a good pore-closing effect, a small pore size, and a large space for storing active ions. Therefore, the carbonaceous material has a high capacity. At the same time, the proportion of the electrolyte wetting area inside the carbonaceous material is low, and the consumption of active ions by the SEI film formation is low. Therefore, the initial irreversible capacity loss of the carbonaceous material is low, and the initial coulombic efficiency is high.

[0144] When the temperature T1 is too low, the true density of the obtained carbonaceous material is small and the interlayer spacing is large. At this time, a large amount of water vapor is adsorbed into the interlayer structure, resulting in a high adsorption mass of water vapor. However, this part of the interlayer structure of the carbonaceous material cannot effectively store active ions, which leads to a decrease in the capacity and initial coulombic efficiency of the carbonaceous material.

[0145] When the temperature T1 is too high, the true density of the carbonaceous material is large and the interlayer spacing is small, which increases the difficulty of active ion insertion and extraction, and reduces the capacity and first coulombic efficiency of the carbonaceous material.

[0146] In some embodiments, in S40, the time t1 can be ≥1h, for example, ≥2h, ≥4h, ≥6h, ≥8h, ≥10h, ≥12h, ≥14h, or ≥16h. When the holding time t1 is within the above range, the heteroatom content of the carbonaceous material can be effectively reduced, resulting in a higher initial coulombic efficiency of the carbonaceous material. If the holding time t1 is short, the oxygen-containing functional groups on some surfaces of the carbonaceous material cannot be effectively reduced, resulting in a higher content of oxygen heteroatoms on the final carbonaceous material. After the oxygen heteroatoms combine with the active ions, they cannot be reversibly inserted or removed, thus reducing the initial coulombic efficiency of the carbonaceous material.

[0147] Furthermore, the heat preservation time t1 should not be too long, as this would result in energy waste due to excessive energy consumption. In some embodiments, the time t1 may optionally be 1h-24h, 2h-24h, 5h-24h, or 10h-24h.

[0148] In some embodiments, in S40, the heating rate can be 0.05℃ / min-1℃ / min, 0.06℃ / min-1℃ / min, 0.08℃ / min-1℃ / min, or 0.1℃ / min-1℃ / min. This can improve production efficiency and reduce energy waste.

[0149] In some embodiments, in S40, the protective gas may include a mixture of hydrogen and an inert gas, wherein the volume concentration of the hydrogen is greater than 0 and less than or equal to 5%, optionally 1%-5%. The volume concentration of hydrogen is ≤5%, primarily for safety reasons. The inert gas may include nitrogen, argon, helium, or combinations thereof.

[0150] During carbonization, if the furnace pressure is too low, the raw material powder will float and disperse into the furnace due to the negative pressure, leading to furnace contamination, reduced yield, and increased risk of dust and protective gas entering the exhaust gas pipe simultaneously. In some embodiments, in S40, the furnace pressure is -5 kPa to -2 kPa, optionally -5 kPa to -3 kPa. This helps ensure safe production.

[0151] In some embodiments, the preparation method further includes: S50, secondary crushing treatment: crushing the carbonaceous material obtained in S40. This process breaks down any carbonaceous material that may have agglomerated during preparation, ensuring the carbonaceous material has the desired particle size for easy preparation of the negative electrode slurry and negative electrode sheet. Of course, in some embodiments, this step can be omitted.

[0152] In some embodiments, the preparation method includes the following steps: S10, providing raw materials: the raw materials are organic carbon sources; S20, crushing treatment: crushing the raw materials to the required particle size; S30, washing and impurity removal treatment: washing and impurity removal treatment of the crushed raw materials obtained in S20, the washing and impurity removal treatment process includes at least an acidic solution washing step and an alkaline solution washing step; S40, carbonization treatment: placing the washed and impurity removed raw materials obtained in S30 in a kiln, introducing a protective gas containing hydrogen, and controlling the furnace pressure to ≤-2kPa, then heating to 1000℃-1600℃ at a rate of ≤1℃ / min, and holding at this temperature for 1h-24h, after which carbonaceous material is obtained, wherein the carbonaceous material is subjected to water vapor adsorption test under constant temperature and humidity conditions of 25℃ and 100%RH, and after standing for 100h, the adsorbed mass of water vapor is recorded as A, the initial mass of the carbonaceous material is recorded as B, and 0.13≤A / B≤0.50. The resulting carbonaceous materials can better balance high capacity and initial coulombic efficiency, thereby further improving the energy density, lifespan, and rate performance of secondary batteries.

[0153] Secondary battery

[0154] The third aspect of this application provides a secondary battery.

[0155] The secondary battery mentioned in the embodiments or implementations of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity. For example, the secondary battery mentioned in this application may include battery cells, battery modules, or battery packs. A battery cell is the smallest unit constituting a secondary battery, capable of charging and discharging independently. This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. Figure 1 The example shown is a square-structured battery cell 5.

[0156] In some embodiments, a single battery cell includes an electrode assembly and an electrolyte, and the single battery cell may also include an outer packaging. The outer packaging can be used to encapsulate the electrode assembly and the electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging can also be a flexible package, such as a pouch-type flexible package. The material of the flexible package can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0157] Electrode assemblies typically include positive and negative electrodes. During the charging and discharging process of a secondary battery, active ions move back and forth between the positive and negative electrodes, inserting and extracting. The electrolyte acts as a conductor for these active ions between the positive and negative electrodes. Electrode assemblies can be manufactured using winding and / or stacking processes.

[0158] In some embodiments, such as Figure 2 As shown, the outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates enclosing a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 is used to cover the opening to close the receiving cavity. Electrode assemblies 52 are encapsulated in the receiving cavity. The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, and can be adjusted as needed.

[0159] In some embodiments of this application, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module. Figure 3 This is a schematic diagram of battery module 4 as an example. Figure 3 As shown, in battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0160] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0161] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack. Figure 4 and Figure 5 This is a schematic diagram of battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3. The upper body 2 covers the lower body 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0162] [Negative electrode plate]

[0163] In some embodiments, the negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector. For example, the negative current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0164] In some embodiments, the negative electrode film layer comprises a carbonaceous material according to the first aspect of this application or a carbonaceous material prepared by the method described in the second aspect of this application. This allows the secondary battery to simultaneously possess high energy density, long lifespan, and good rate performance.

[0165] In some embodiments, the negative electrode film layer may further include other negative electrode active materials besides the carbonaceous materials described above. In some embodiments, the other negative electrode active materials include, but are not limited to, one or more of natural graphite, artificial graphite, soft carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based materials may include one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based materials may include one or more of elemental tin, tin oxide, and tin alloys.

[0166] In some embodiments, the negative electrode film layer may optionally include a negative electrode conductive agent. This application does not impose any particular limitation on the type of negative electrode conductive agent. As an example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0167] In some embodiments, the negative electrode film layer may optionally include a negative electrode binder. This application does not impose any particular limitation on the type of negative electrode binder. As an example, the negative electrode binder may include one or more of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0168] In some embodiments, the negative electrode film may optionally include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0169] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0170] The negative electrode film layer is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is typically formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0171] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet of this application further includes a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector; in some embodiments, the negative electrode sheet of this application further includes a protective layer covering the surface of the negative electrode film layer.

[0172] [Positive electrode plate]

[0173] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector. For example, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0174] The positive electrode current collector can be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil can be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0175] The positive electrode film typically comprises a positive electrode active material, an optional binder, and an optional conductive agent. The positive electrode film is typically formed by coating a positive electrode slurry onto the positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is typically formed by dispersing the positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent and stirring until homogeneous. The solvent may be N-methylpyrrolidone (NMP), but is not limited to it. As an example, the binder used for the positive electrode film may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins. As an example, the conductive agent used for the positive electrode film includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0176] The positive electrode active material may be a positive electrode active material known in the art for use in secondary batteries.

[0177] When the secondary battery of this application is a lithium-ion battery, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds. Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds.

[0178] In some embodiments, to further improve the energy density of secondary batteries, the positive electrode active material for lithium-ion batteries may include materials with the general formula Li. a Ni b Co c M d O e A f One or more of lithium transition metal oxides and their modified compounds. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes one or more selected from Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes one or more selected from N, F, S and Cl.

[0179] As an example, positive electrode active materials for lithium-ion batteries may include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 One or more of O2, LiFePO4 and LiMnPO4.

[0180] When the secondary battery of this application is a sodium-ion battery, the positive electrode active material may include, but is not limited to, one or more of sodium-containing transition metal oxides, polyanionic materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian blue materials.

[0181] As an example, positive electrode active materials for sodium-ion batteries may include NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, and NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue materials and materials with the general formula X p M' q (PO4) r O x Y 3-x One or more of the materials. In general formula X p M' q (PO4) r O x Y 3-x In the given condition, 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, and X includes elements selected from H. + Li + Na + K+ and NH4 + One or more of the following, M' is a transition metal cation, optionally including one or more selected from V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, optionally including one or more selected from F, Cl and Br.

[0182] In this application, the modified compounds of the above-mentioned positive electrode active materials may be those that have undergone doping modification and / or surface coating modification of the positive electrode active materials.

[0183] [Electrolytes]

[0184] This application does not impose any particular limitation on the type of electrolyte, which can be selected according to actual needs. For example, the electrolyte can be selected from at least one of solid electrolytes and liquid electrolytes (i.e., electrolyte solutions).

[0185] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0186] The type of electrolyte salt is not specifically limited and can be selected according to actual needs.

[0187] When the secondary battery of this application is a lithium-ion battery, as an example, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0188] When the secondary battery of this application is a sodium-ion battery, the electrolyte salt may include one or more of the following: sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalate borate (NaDFOB), sodium dioxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0189] The type of solvent is not specifically limited and can be selected according to actual needs. In some embodiments, as an example, the solvent may include one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0190] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.

[0191] [Isolation membrane]

[0192] Secondary batteries using electrolytes, and some secondary batteries using solid electrolytes, also include a separator. The separator is disposed between the positive electrode and the negative electrode, serving as a barrier. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0193] In some embodiments, the material of the separator may include one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.

[0194] [Preparation Method]

[0195] The method for preparing the secondary battery described in this application is well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a secondary battery. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with an electrolyte. After vacuum sealing, settling, formation, and shaping processes, a battery cell is obtained. Multiple battery cells can be further connected in series, parallel, or a combination thereof to form a battery module. Multiple battery modules can also be connected in series, parallel, or a combination thereof to form a battery pack. In some embodiments, multiple battery cells can also be directly assembled into a battery pack.

[0196] Electricity-using device

[0197] A fourth aspect of this application provides an electrical device, which includes the secondary battery described in this application. The secondary battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may be, but is not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0198] The electrical device can select the specific type of secondary battery according to its usage requirements, such as a battery cell, battery module, or battery pack.

[0199] Figure 6 This is a schematic diagram illustrating an example of an electrical device. This device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used as the power source.

[0200] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0201] Example

[0202] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0203] Example 1

[0204] Commercially available coconut shells were crushed using an air jet mill to achieve a particle size distribution (D50) of 6.8 ± 0.5 μm and a D90 of 13.7 ± 0.5 μm. The powder was then washed with a 3 mol / L perchloric acid aqueous solution at 60 °C for 12 h, followed by washing with deionized water until neutral. Next, it was washed with a 3 mol / L NaOH aqueous solution at 95 °C for 24 h, and then washed again with deionized water until neutral. Finally, the powder was dried by forced air to remove moisture. The dried powder was placed in a kiln and heated to 1400 °C at a rate of 0.1 °C / min under a hydrogen / argon mixed gas atmosphere of 5:95 and a furnace pressure of -5 kPa. The temperature was then held for 24 h, yielding carbonaceous material.

[0205] In a constant temperature and humidity chamber at 25℃ and 100%RH, a carbonaceous material of mass B is evenly placed in a petri dish with a diameter of 10cm and the thickness of the carbonaceous material stack is ≤0.2cm. After standing for 100h, the increase in mass of the carbonaceous material is weighed and recorded as the adsorption mass of water vapor A.

[0206] The true density of carbonaceous materials was tested using the Archimedes impregnation volume displacement method with n-butanol as the medium.

[0207] Examples 2-16 and Comparative Examples 1-6

[0208] The preparation method of carbonaceous materials is similar to that in Example 1, except that the preparation process parameters of carbonaceous materials are adjusted, as detailed in Table 1.

[0209] Comparative Example 7

[0210] Commercially available coconut shells were crushed using an air jet mill to achieve a particle size distribution (D50) of 6.8 ± 0.5 μm and a D90 of 13.7 ± 0.5 μm. The powder was then washed with a 3 mol / L perchloric acid aqueous solution at 60 °C for 12 h, followed by washing with deionized water until neutral. The powder was then dried by forced air to remove moisture. The dried powder was placed in a kiln and heated to 1400 °C at a rate of 0.1 °C / min under a hydrogen / argon mixed gas atmosphere of 5:95 and a furnace pressure of -5 kPa. The temperature was then maintained for 24 h, yielding carbonaceous material.

[0211] Comparative Example 8

[0212] Commercially available coconut shells were crushed using an air jet mill to achieve a particle size distribution (D50) of 6.8 ± 0.5 μm and a D90 of 13.7 ± 0.5 μm. The powder was then washed with a 3 mol / L NaOH aqueous solution at 95 °C for 24 h, followed by washing with deionized water until neutral. The powder was then dried by forced air to remove moisture. The dried powder was placed in a kiln and heated to 1400 °C at a rate of 0.1 °C / min under a hydrogen / argon mixed gas atmosphere of 5:95 and a furnace pressure of -5 kPa. The temperature was then held for 24 h, yielding carbonaceous material.

[0213] Comparative Example 9

[0214] Commercially available coconut shells were crushed using an air jet mill to a volumetric particle size of D50 of 6.8±0.5μm and D90 of 13.7±0.5μm. The powder was then placed in a kiln and heated to 1400℃ at a rate of 0.1℃ / min under a mixed gas atmosphere of hydrogen / argon volume ratio of 5:95 and a furnace pressure of -5kPa. The temperature was then maintained for 24 hours, and carbonaceous material was obtained after the treatment.

[0215] Comparative Example 10

[0216] Commercially available coconut shells were washed with a 3 mol / L perchloric acid aqueous solution at 60°C for 12 h, then washed with deionized water until neutral, followed by washing with a 3 mol / L NaOH aqueous solution at 95°C for 24 h, and then washed with deionized water until neutral. The shells were then dried by forced air to remove moisture. The dried coconut shells were then crushed using an air jet mill to a particle size distribution (D50) of 6.8 ± 0.5 μm and a D90 of 13.7 ± 0.5 μm. The powder was then placed in a kiln and heated to 1400°C at a rate of 0.1°C / min under a hydrogen / argon mixed gas atmosphere of 5:95 and a furnace pressure of -5 kPa. The temperature was then held for 24 h, yielding carbonaceous material.

[0217] Performance test

[0218] The carbonaceous materials prepared in the various embodiments and comparative examples were thoroughly mixed with styrene-butadiene rubber (SBR) as a binder, sodium carboxymethyl cellulose (CMC-Na) as a thickener, and carbon black as a conductive agent in a mass ratio of 96.2:1.8:1.2:0.8 in an appropriate amount of deionized water to form a uniform negative electrode slurry. The negative electrode slurry was uniformly coated onto the surface of the copper foil current collector and dried in an oven for later use. Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. NaPF6 was then dissolved in the organic solvent to prepare an electrolyte with a concentration of 1 mol / L. A CR2430 coin cell was then assembled in an argon-protected glove box using a sodium metal sheet as the counter electrode and a polyethylene (PE) film as the separator.

[0219] At 25°C, the coin cells prepared in each example and comparative example were first discharged to 0V at a constant current density of 10mA / g, and the first discharge capacity of the coin cells was recorded; then, they were charged to 2.0V at a constant current density of 10mA / g, and the first charge capacity of the coin cells was recorded.

[0220] The reversible specific capacity (mAh / g) of carbonaceous material = the first charge capacity of the coin cell / the mass of the carbonaceous material.

[0221] The initial coulombic efficiency (%) of carbonaceous materials = the first charge capacity of the coin cell / the first discharge capacity of the coin cell × 100%.

[0222] Table 1

[0223]

[0224]

[0225] Figure 7 and Figure 8 This is a scanning electron microscope image of the carbonaceous material provided in this application, such as... Figure 7 and Figure 8 As shown, the carbonaceous material provided in this application has an irregular polygonal morphology. Based on the test results in Table 1, it can be seen that when the carbonaceous material is subjected to constant temperature and humidity conditions of 25℃ and 100%RH, and the ratio of water vapor adsorbed per unit mass of carbonaceous material within 100 hours is between 0.13 and 0.50, the carbonaceous material can achieve both high capacity and initial coulombic efficiency.

[0226] The carbonaceous materials prepared in Comparative Examples 1-10, under constant temperature and humidity conditions of 25℃ and 100%RH, showed that the mass ratio of water vapor adsorbed per unit mass of carbonaceous material within 100h was either less than 0.13 or greater than 0.50. Consequently, the carbonaceous materials could not achieve both high capacity and initial coulombic efficiency.

[0227] The test results from Examples 1 and 8-10 also show that when the parameters A / B of the carbonaceous material are close, the capacity and initial coulombic efficiency of the carbonaceous material can be further improved by giving it a higher true density. This is because the carbonaceous material obtained in Example 8 has a large interlayer spacing, resulting in a high adsorption mass of water vapor due to the large amount of water vapor adsorbed into the interlayer structure. However, because n-butanol liquid cannot enter the interlayer structure of the carbonaceous material, the true density test value is low. Furthermore, since the interlayer structure of the carbonaceous material obtained in Example 8 cannot effectively store active ions, its capacity and initial coulombic efficiency are lower compared to Examples 1 and 9-10.

[0228] Therefore, when the carbonaceous material simultaneously satisfies the following conditions: the mass ratio of water vapor adsorbed per unit mass of carbonaceous material within 100 hours is between 0.13 and 0.50, and the true density ρ is between 1.0 g / cm³, then... 3 Up to 1.6 g / cm 3 Between, optionally at 1.05 g / cm³ 3 Up to 1.45 g / cm 3 In between, the capacity and initial coulombic efficiency of carbonaceous materials can be further improved.

[0229] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A carbonaceous material for a negative electrode sheet in a secondary battery, wherein the carbonaceous material is subjected to an adsorption test using water vapor under constant temperature and humidity conditions of 25°C and 100%RH, and after standing for 100 hours, the adsorbed mass of water vapor is denoted as A, the initial mass of the carbonaceous material is denoted as B, 0.13 ≤ A / B ≤ 0.50, and the specific surface area of ​​the carbonaceous material is 0.1 m². 2 / g-10m 2 / g.

2. The carbonaceous material according to claim 1, wherein, 0.15≤A / B≤0.

50.

3. The carbonaceous material according to claim 2, wherein, 0.30≤A / B≤0.

496.

4. The carbonaceous material according to any one of claims 1-3, wherein, The true density ρ of the carbonaceous material is 1.0 g / cm³. 3 -1.6g / cm 3 .

5. The carbonaceous material according to claim 4, wherein, The true density ρ of the carbonaceous material is 1.05 g / cm³. 3 -1.45g / cm 3 .

6. The carbonaceous material according to any one of claims 1-5, wherein, The carbonaceous material includes multiple nanoporous structures.

7. The carbonaceous material according to claim 6, wherein, The carbonaceous material comprises multiple pore structures with pore sizes below 10 nm.

8. The carbonaceous material according to any one of claims 1-7, wherein, In the Raman spectrum of the carbonaceous material, I d / I g The value is 1.0-1.3, I d This indicates that the Raman displacement is within 1350±50cm. -1 The d-peak intensity within the range, I g This indicates that the Raman displacement is within 1580±50cm. -1 The intensity of the g peak within the range; and / or, The interlayer spacing of the (002) crystal plane of the carbonaceous material is ≥0.37 nm; and / or, In the X-ray diffraction spectrum of the carbonaceous material, the 2θ value corresponding to the (002) crystal plane peak is between 22° and 24°.

9. The carbonaceous material according to claim 8, wherein, I d / I g For 1.05-1.15; and / or, The interlayer spacing of the (002) crystal plane of the carbonaceous material is 0.37nm-0.42nm.

10. The carbonaceous material according to any one of claims 1-9, wherein, The carbonaceous material satisfies at least one of the following conditions (1) to (5): (1) The volumetric particle size Dv50 of the carbonaceous material is 3μm-7μm; (2) The volumetric particle size Dv90 of the carbonaceous material is 8μm-15μm; (3) The specific surface area of ​​the carbonaceous material is 1m². 2 / g-5m 2 / g; (4) The compacted density of the carbonaceous material under a force of 50,000 N is 0.90 g / cm³. 3 -1.05g / cm 3 ; (5) The tap density of the carbonaceous material is 0.80 g / cm³. 3 -0.95g / cm 3 .

11. The carbonaceous material according to claim 10, wherein, The carbonaceous material satisfies at least one of the following conditions (1) to (4): (1) The volumetric particle size Dv50 of the carbonaceous material is 4μm-6μm; (2) The volumetric particle size Dv90 of the carbonaceous material is 9μm-12μm; (3) The compacted density of the carbonaceous material under a force of 50,000 N is 0.93 g / cm³. 3 -1.02g / cm 3 ; (4) The tap density of the carbonaceous material is 0.85 g / cm³. 3 -0.90g / cm 3 .

12. A method for preparing a carbonaceous material for a negative electrode sheet of a secondary battery, comprising the following steps: S10, Providing raw materials: The raw materials are organic carbon sources; S20, Crushing process: Crushing the raw material to the required particle size; S30, Washing and impurity removal treatment: The crushed raw material obtained in S20 is subjected to washing and impurity removal treatment, the washing and impurity removal treatment process includes at least an acidic solution washing step and an alkaline solution washing step; S40, Carbonization Treatment: The washed and purified raw material obtained in S30 is placed in a kiln, a protective gas containing hydrogen is introduced, and the furnace pressure is controlled at ≤-2kPa. The temperature is then increased to the target temperature T1 at a rate of ≤1℃ / min, and then held at the target temperature T1 for a target time t1. After this treatment, carbonaceous material is obtained. The carbonaceous material was subjected to an adsorption test using water vapor under constant temperature and humidity conditions of 25℃ and 100%RH. After standing for 100 hours, the adsorbed mass of water vapor was recorded as A, and the initial mass of the carbonaceous material was recorded as B. The ratio of A / B to the adsorption mass was 0.13 ≤ A / B ≤ 0.50, and the specific surface area of ​​the carbonaceous material was 0.1 m². 2 / g-10m 2 / g.

13. The method according to claim 12, wherein, In S20, the crushing includes ball milling or air jet milling.

14. The method according to claim 12 or 13, wherein, In S30, the washing and impurity removal process sequentially includes the following steps: acidic solution washing, water washing, alkaline solution washing, water washing, and drying; or, In S30, the washing and impurity removal process includes the following steps in sequence: alkaline solution washing, water washing, acidic solution washing, water washing, and drying.

15. The method according to any one of claims 12-14, wherein, In S30, the acidic solution satisfies at least one of the following conditions (1) to (4): (1) The H+ of the acidic solution + Concentrations range from 0.1 mol / L to 6 mol / L; (2) The washing temperature of the acidic solution is 10℃-95℃; (3) The washing time of the acidic solution is 1h-24h; (4) The solute of the acidic solution includes one or more of hydrochloric acid, nitric acid, sulfuric acid and perchloric acid, and the solvent includes water.

16. The method according to claim 15, wherein, In S30, the acidic solution satisfies at least one of the following conditions (1) to (3): (1) The H+ of the acidic solution + Concentrations range from 1 mol / L to 6 mol / L; (2) The washing temperature of the acidic solution is 30℃-95℃; (3) The washing time of the acidic solution is 10h-24h.

17. The method according to any one of claims 12-16, wherein, In S30, the alkaline solution satisfies at least one of the following conditions (1) to (4): (1) The OH- of the alkaline solution - Concentrations range from 0.1 mol / L to 6 mol / L; (2) The washing temperature of the alkaline solution is 10℃-95℃; (3) The washing time of the alkaline solution is 1h-24h; (4) The solute of the alkaline solution includes NaOH, KOH or a combination thereof, and the solvent includes water.

18. The method according to claim 17, wherein, In S30, the alkaline solution satisfies at least one of the following conditions (1) to (3): (1) The OH- of the alkaline solution - Concentrations range from 1 mol / L to 6 mol / L; (2) The washing temperature of the alkaline solution is 30℃-95℃; (3) The washing time of the alkaline solution is 10h-24h.

19. The method according to any one of claims 12-18, wherein, In S40, the temperature T1 is 1000℃-1600℃; and / or, In S40, the time t1 is ≥1h; and / or, In S40, the heating rate is 0.05℃ / min - 1℃ / min; and / or, In S40, the protective gas comprises a mixture of hydrogen and an inert gas, wherein the volume concentration of the hydrogen is greater than 0 and less than or equal to 5%; and / or, In S40, the furnace pressure is -5 kPa to -2 kPa.

20. The method according to claim 19, wherein, In S40, the temperature T1 is 1150℃-1500℃; and / or, In S40, the time t1 is 10h-24h; and / or, In S40, the heating rate is 0.1℃ / min - 1℃ / min; and / or, In S40, the protective gas comprises a mixture of hydrogen and an inert gas, and the volume concentration of the hydrogen is 1%-5%; and / or, In S40, the furnace pressure is -5 kPa to -3 kPa.

21. The method according to any one of claims 12-20, wherein, In S10, the organic carbon source includes one or more of biomass materials and thermoplastic resin materials.

22. The method according to claim 21, wherein, The biomass materials include one or more of energy crops and biomass waste.

23. The method according to claim 21, wherein, The thermoplastic resin material includes one or more of phenolic resin, acrylic resin, polyvinyl chloride, polycarbonate, epoxy resin, polyoxymethylene, coumarone resin and petroleum resin.

24. A secondary battery, comprising a negative electrode, said negative electrode comprising the carbonaceous material according to any one of claims 1-11 or the carbonaceous material prepared by the method according to any one of claims 12-23.

25. An electrical device comprising the secondary battery of claim 24.

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