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

Abstract

The present application provides a carbonaceous material, a preparation method thereof, and a secondary battery and an electric device containing the same, wherein the carbonaceous material satisfies A / B≥1.7 cm ‑8 / (g×h) STP in a CO2 adsorption test at 0℃, a relative pressure P / P0 between 10 3 and 0.029, A is the total amount of CO2 adsorbed, and B is the adsorption time, wherein P represents the test pressure of CO2, and P0 represents the saturated vapor pressure of CO2 at 0℃. The carbonaceous material of the present application can balance a higher capacity and a first coulombic efficiency.

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 hydroelectric, 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 improvement of 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 present application aims to provide a carbonaceous material and a preparation method thereof, and a secondary battery and an electric device containing the same, which are designed to simultaneously improve the capacity and the first coulombic efficiency of the carbonaceous material.

[0004] The present application provides a carbonaceous material in a first aspect, which satisfies the following conditions in a CO2 adsorption test: in a CO2 adsorption test, at 0℃, the total amount of CO2 adsorbed when the relative pressure P / P0 is between 10 -8 and 0.029 is denoted as A, and the adsorption time is denoted as B, and the carbonaceous material satisfies: A / B≥1.7 cm 3 / (g×h)STP, STP is the standard state, P represents the test pressure of CO2, and P0 represents the saturated vapor pressure of CO2 at 0℃.

[0005] The present inventors found in the research process that in a CO2 adsorption test of a carbonaceous material, the ratio A / B of the total amount of CO2 adsorbed A when the relative pressure P / P0 is between 10 -8 and 0.029 and the CO2 adsorption time B corresponding to the adsorption amount can reflect the space content in the carbonaceous material that is suitable for the storage and reversible deintercalation and intercalation of active ions. When A / B≥1.7 cm 3 / (g×h)STP, the CO2 adsorption rate is fast, it is considered that the carbonaceous material contains more space suitable for the storage of active ions, and the availability of the space is also high, so the carbonaceous material of the present application can balance the high capacity and the first coulombic efficiency, and also enables the secondary battery to have high energy density, long service life and good rate performance at the same time.

[0006] In any embodiment of the present application, 1.7 cm 3 / (g x h)STP≤ A / B ≤ 20 cm 3 / (g x h)STP, optionally 3.0 cm 3 / (g x h)STP≤ A / B ≤ 20 cm 3 / (g x h)STP. At this time, the carbonaceous material contains more space suitable for storing active ions and / or the space is more available, thereby further improving the capacity and the first coulombic efficiency of the carbonaceous material.

[0007] In any embodiment of the present application, B≥ 5 h, optionally 5 h≤ B≤ 10 h. When the CO2 adsorption time B is longer, it is considered that the carbonaceous material contains more space suitable for storing active ions, thereby the capacity of the carbonaceous material is higher.

[0008] In any embodiment of the present application, A≥ 10 cm 3 / gSTP, optionally 15 cm 3 / gSTP≤ A≤ 200 cm 3 / gSTP. When the total amount of CO2 adsorption A is higher, it is considered that the carbonaceous material contains more space suitable for storing active ions, thereby the capacity of the carbonaceous material is higher.

[0009] In any embodiment of the present application, the true density p of the carbonaceous material is ≤ 1.45 g / cm 3 , optionally 1.0 g / cm 3 -1.45 g / cm 3 When the true density of the carbonaceous material satisfies the above specific range, it is helpful to further improve the capacity and the first coulombic efficiency of the carbonaceous material.

[0010] In any embodiment of the present application, the carbonaceous material comprises a plurality of nanopore structures, optionally the carbonaceous material comprises a plurality of pore structures with a pore size of less than 10 nm.

[0011] In any embodiment of the present application, in the Raman spectrum of the carbonaceous material, I d / I g is 0.90-1.25, 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 -1.25, I g represents the intensity of the G-peak with a Raman shift in the range of 1580±50 cm -1The g-peak intensity is within the specified range. At this point, the carbonaceous material structure exhibits moderate order, resulting in higher capacity and higher initial coulombic efficiency, while also possessing good rate performance.

[0012] In any embodiment of this application, the interlayer spacing of the (002) crystal plane of the carbonaceous material is ≥0.37nm, and can be selected as 0.37nm-0.42nm.

[0013] In any embodiment of this application, 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°.

[0014] In any embodiment of this application, the volumetric particle size Dv50 of the carbonaceous material is 3μm-15μm, and can be selected as 4μm-6μm.

[0015] In any embodiment of this application, the volumetric particle size Dv90 of the carbonaceous material is 8μm-30μm, and can be selected as 9μm-12μm.

[0016] 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.

[0017] In any embodiment of this application, the specific surface area of ​​the carbonaceous material is 1 m². 2 / g-10m 2 / g, optional 1m 2 / g-5m 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.

[0018] 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.

[0019] 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 -0.9g / cm 3When 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.

[0020] A second aspect of this application provides a method for preparing a carbonaceous material, comprising the following steps:

[0021] S10, Providing raw materials: The raw materials are organic carbon sources;

[0022] S20, Crushing process: The raw material is crushed.

[0023] S30, Washing and impurity removal treatment; The crushed raw material obtained in S20 is subjected to washing and impurity removal treatment, wherein the washing and impurity removal treatment process includes at least an acidic solution washing step and an alkaline solution washing step.

[0024] S40, Low-temperature pre-carbonization treatment: The raw material obtained by S30 after washing and removing impurities is placed in a kiln. Under the conditions of protective gas atmosphere and furnace pressure of ≤-2kPa, the temperature is raised to the first temperature T1 at the first rate of ≥20℃ / min. Then, it is held at the first temperature T1 for a first time t1. After the treatment, preheated decarbonization is obtained.

[0025] S50, high-temperature carbonization treatment: The preheated decomposed carbon obtained from S40 is placed in a kiln under a protective gas atmosphere, with a furnace pressure of ≤-2kPa and a packing density of ≤0.6g / cm³. 3 Under the conditions described, the temperature is increased to a second temperature T2 at a second rate, and then held at the second temperature T2 for a second time t2. After the holding time is completed, a carbonaceous material is obtained. The carbonaceous material, in a CO2 adsorption test, at 0°C and a relative pressure P / P0 of 10... -8 The total CO2 adsorption amount between 0.029 and 0.029 is denoted as A, and the adsorption time is denoted as B. The carbonaceous material satisfies the following condition: A / B ≥ 1.7 cm⁻¹. 3 / (g×h)STP, where STP represents standard conditions, P represents the test pressure of CO2, and P0 represents the saturated vapor pressure of CO2 at 0℃.

[0026] The carbonaceous material obtained by the preparation method provided in this application has a large amount of active ion storage space and a high space utilization rate, which enables the carbonaceous material to achieve both high capacity and first coulombic efficiency, and also enables the secondary battery to have high energy density, long service life and good rate performance.

[0027] In any embodiment of this application, in S10, the organic carbon source includes one or more of biomass materials and thermoplastic resin materials.

[0028] In any embodiment of this application, the biomass material includes one or more of energy crops and biomass waste.

[0029] 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.

[0030] 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.

[0031] 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.

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

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

[0034] 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 is water.

[0035] 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.

[0036] 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.

[0037] In any embodiment of this application, the washing temperature of the alkaline solution is 10℃-95℃, and can be selected as 30℃-95℃.

[0038] In any embodiment of this application, the washing time of the alkaline solution is 1h-24h, and can be selected as 10h-24h.

[0039] In any embodiment of this application, the solute of the alkaline solution includes NaOH, KOH, or a combination thereof, and the solvent is water.

[0040] 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.

[0041] In any embodiment of this application, in S40, the temperature T1 is 300℃-600℃, optionally 400℃-500℃. A first temperature T1 within a suitable range is beneficial for forming a through-hole structure, providing a rapid dissipation channel.

[0042] In any embodiment of this application, in S40, the time t1 is 1h-24h, and can be selected as 6h-12h.

[0043] In any embodiment of this application, in S40, the heating rate is 20°C / min-35°C / min, optionally 25°C / min-30°C / min. This allows the carbonaceous material to better balance high capacity and initial coulombic efficiency.

[0044] In any embodiment of this application, in S40, the protective gas includes nitrogen, argon, helium, or a combination thereof.

[0045] In any embodiment of this application, in S40, the furnace pressure is -5 kPa to -2 kPa, optionally -4.5 kPa to -3 kPa. This helps to ensure safe production.

[0046] In any embodiment of this application, in S50, the temperature T2 is 1000℃-1600℃, optionally 1200℃-1400℃. When the second temperature T2 is within a suitable range, it can create a closed-pore effect on the preheated decomposed carbon obtained by low-temperature precarbonization treatment, thereby reducing the contact area between the carbon material and the electrolyte, i.e., reducing the consumption of active ions by the SEI film formation, and improving the first coulombic efficiency of the carbon material; it can also cause the preheated decomposed carbon obtained by low-temperature precarbonization treatment to undergo aromatic cyclization, thereby improving the order and conductivity of the carbon material, while removing excess O and H elements from the carbon skeleton structure, and helping to form an ordered pseudo-graphite microcrystalline structure.

[0047] In any embodiment of this application, in S50, the time t1 is 1h-24h, and can be selected as 6h-12h.

[0048] In any embodiment of this application, in S50, the heating rate is 1°C / min-10°C / min, optionally 3°C / min-5°C / min. This is beneficial for improving the capacity and / or initial coulombic efficiency of carbonaceous materials.

[0049] In any embodiment of this application, in S50, the protective gas includes nitrogen, argon, helium, or a combination thereof.

[0050] In any embodiment of this application, in S50, the furnace pressure is -5 kPa to -2 kPa, optionally -4.5 kPa to -3 kPa. This helps to ensure safe production.

[0051] 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.

[0052] The fourth aspect of this application provides an electrical device that includes the secondary battery of the third aspect of this application.

[0053] The carbonaceous material provided in this application has a large amount of active ion storage space and a high space utilization rate. This allows the carbonaceous material to achieve both high capacity and initial coulombic efficiency, and also enables the secondary battery to simultaneously possess high energy density, long service life, and good rate performance. The power supply device of this application includes the secondary battery provided in this application, and therefore has at least the same advantages as the aforementioned secondary battery. Attached Figure Description

[0054] 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.

[0055] Figure 1 This is a schematic diagram of one embodiment of the battery cell of this application.

[0056] Figure 2 This is an exploded view of one embodiment of the battery cell of this application.

[0057] Figure 3 This is a schematic diagram of one embodiment of the battery module of this application.

[0058] Figure 4 This is a schematic diagram of one embodiment of the battery pack of this application.

[0059] Figure 5 yes Figure 4 An exploded view of an embodiment of the battery pack shown.

[0060] 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.

[0061] Figure 7 This is a graph showing the total adsorption amount versus adsorption time of the carbonaceous material prepared in Example 1 for CO2 adsorption testing.

[0062] Figure 8 This is a graph showing the total adsorption amount versus relative pressure P / P0 curve of the carbonaceous material prepared in Example 1 for CO2 adsorption testing.

[0063] Figure 9 This is a graph showing the total adsorption amount versus adsorption time of the carbonaceous material prepared in Comparative Example 1 for CO2 adsorption testing.

[0064] Figure 10 This is a graph showing the total adsorption amount versus relative pressure P / P0 curve of the carbonaceous material prepared in Comparative Example 1 for CO2 adsorption testing.

[0065] 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

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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).

[0073] Unless otherwise specified, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0074] 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.

[0075] 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.

[0076] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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 280 mAh / g, and the initial coulombic efficiency is usually below 80%, which severely limits their practical applications.

[0082] Therefore, how to simultaneously improve the capacity and first coulomb efficiency of hard carbon remains a pressing technical challenge.

[0083] 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.

[0084] Carbonaceous material

[0085] The carbonaceous material provided in this application, in a CO2 adsorption test at 0°C and a relative pressure P / P0 of 10, showed promising results. -8 The total CO2 adsorption amount between 0.029 and 0.029 is denoted as A, and the adsorption time is denoted as B. The carbonaceous material satisfies the following condition: A / B ≥ 1.7 cm⁻¹. 3 / (g×h)STP, where STP stands for Standard Temperature and Pressure, P represents the test pressure of CO2, and P0 represents the saturated vapor pressure of CO2 at 0℃.

[0086] In this application, the CO2 adsorption test of carbonaceous materials can be performed according to GB / T 21650.2-2008, using a surface area and pore size analyzer. The testing instrument can be the ASAP 2460 surface area and pore size analyzer from Micromeritics, USA.

[0087] Compared to currently commercially available hard carbon, the carbonaceous material provided in this application achieves both high capacity and high first-time 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 with abundant and highly usable active ion storage space, which facilitates the insertion, storage, and extraction of active ions, thereby enabling the carbonaceous material provided in this application to achieve both high capacity and high first-time coulombic efficiency.

[0088] During their research, the inventors of this application discovered that in CO2 adsorption tests of carbonaceous materials, at 0°C and a relative pressure P / P0 of 10... -8The ratio A / B, which is the total CO2 adsorption amount A to 0.029 and the corresponding CO2 adsorption time B, reflects the space content in carbonaceous materials suitable for the storage and reversible extraction and insertion of active ions. A / B ≥ 1.7 cm⁻¹ 3 / (g×h)STP, CO2 adsorption rate is relatively fast, it is believed that the carbonaceous material contains a lot of space suitable for the storage of active ions, and the space utilization rate is also high. Therefore, the carbonaceous material of this application can take into account high capacity and first coulombic efficiency, and can also enable the secondary battery to have high energy density, long service life and good rate performance.

[0089] A / B is less than 1.7cm 3 At / (g×h)STP, the CO2 adsorption rate is very slow. It is believed that the space inside the carbonaceous material that is suitable for storing active ions is very small and / or the space utilization rate is very low. As a result, the capacity of the carbonaceous material is low and the initial coulombic efficiency is also low.

[0090] In some embodiments, A / B can be ≥2.0 cm. 3 / (g×h)STP,≥3.0cm 3 / (g×h)STP,≥4.0cm 3 / (g×h)STP,≥5.0cm 3 / (g×h)STP,≥6.0cm 3 / (g×h)STP,≥7.0cm 3 / (g×h)STP,≥8.0cm 3 / (g×h)STP. Optional, 1.7cm 3 / (g×h)STP≤A / B≤20cm 3 / (g×h)STP, 3.0cm 3 / (g×h)STP≤A / B≤20cm 3 / (g×h)STP, 5.0cm 3 / (g×h)STP≤A / B≤20cm 3 / (g×h)STP, 8.0cm 3 / (g×h)STP≤A / B≤20cm 3 / (g×h)STP. At this point, the carbonaceous material contains more space suitable for storing active ions and / or has a higher space utilization rate, thereby further improving the capacity and first coulombic efficiency of the carbonaceous material.

[0091] In some embodiments, B ≥ 5h. For example, B can be ≥ 5h, ≥ 5.5h, ≥ 6h, ≥ 6.5h, ≥ 7h, and optionally, 5h ≤ B ≤ 10h, 5.5h ≤ B ≤ 10h, 6h ≤ B ≤ 10h, 6.5h ≤ B ≤ 10h, and 7h ≤ B ≤ 10h. When the CO2 adsorption time B is longer, it is believed that the carbonaceous material contains more space suitable for storing active ions, thus the carbonaceous material has a higher capacity. When the CO2 adsorption time B is shorter, the carbonaceous material reaches adsorption equilibrium in a shorter time, it is believed that the carbonaceous material contains less space suitable for storing active ions and / or the space utilization rate is very low, thus the carbonaceous material has a lower capacity and a lower initial coulombic efficiency.

[0092] In some embodiments, A ≥ 10 cm 3 / gSTP. For example, A can be ≥18cm 3 / gSTP, ≥20cm 3 / gSTP, ≥30cm 3 / gSTP, ≥50cm 3 / gSTP, ≥60cm 3 / gSTP, ≥80cm 3 / gSTP, optional, 15cm 3 / gSTP≤A≤200cm 3 / gSTP, 20cm 3 / gSTP≤A≤200cm 3 / gSTP, 30cm 3 / gSTP≤A≤200cm 3 / gSTP, 50cm 3 / gSTP≤A≤200cm 3 / gSTP, 80cm 3 / gSTP≤A≤200cm 3 / gSTP. A higher total CO2 adsorption A indicates that the carbonaceous material contains more space suitable for storing active ions, thus resulting in a higher capacity. A lower total CO2 adsorption A indicates that the carbonaceous material contains less space suitable for storing active ions, thus resulting in a lower capacity.

[0093] 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.

[0094] In some embodiments, the true density ρ of the carbonaceous material is ≤1.45 g / cm³. 3For example, the true density ρ of the carbonaceous material can be ≤1.40 g / cm³. 3 ≤1.38g / cm 3 ≤1.36g / cm 3 ≤1.34g / cm 3 ≤1.30g / cm 3 Optionally, the true density ρ of the carbonaceous material is 1.0 g / cm³. 3 -1.45g / cm 3 1.0g / cm 3 -1.40g / cm 3 1.0g / cm 3 -1.38g / cm 3 1.0g / cm 3 -1.36g / cm 3 1.0g / cm 3 -1.34g / cm 3 1.0g / cm 3 -1.32g / cm 3 1.0g / cm 3 -1.30g / cm 3 When the true density of carbonaceous materials meets the specific range mentioned above, it helps to further improve the capacity and first coulombic efficiency of carbonaceous materials.

[0095] When the true density of carbonaceous materials is 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 large pore structures. As a result, the microporous and / or small mesoporous structures are easily exposed to the electrolyte, which reduces the storage space of active ions and thus reduces the capacity and first coulombic efficiency of the carbonaceous material.

[0096] When the true density of carbonaceous materials is low, it is assumed that the microporous and / or mesoporous structures are abundant and have good pore-closing effects. In this case, the space into which the calibration liquid (e.g., n-butanol) enters is less than the actual pore space of the carbonaceous material, and these unentered pores can store active ions. Simultaneously, the electrolyte is less likely to penetrate the interior of the carbonaceous material particles, thus reducing the consumption of active ions during the formation of the solid electrolyte interphase (SEI) membrane. However, the true density of carbonaceous materials should not be too low, as this might result in excessively good pore-closing effects, making it difficult for active ions to embed and be stored.

[0097] 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.

[0098] 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.

[0099] In some embodiments, the C content in the carbonaceous material may be ≥90wt%, and may be 90wt%-98wt%.

[0100] In some embodiments, the oxygen content in the carbonaceous material may be 2wt%-8wt%.

[0101] In some embodiments, the hydrogen content in the carbonaceous material may be ≤0.3wt%, and may be 0.1-0.2wt%.

[0102] In some embodiments, the nitrogen content in the carbonaceous material may be ≤0.3wt%, and may be 0.01wt%-0.1wt%.

[0103] 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%.

[0104] In some embodiments, the sulfur content in the carbonaceous material may be ≤0.2wt%, and may be 0.01wt%-0.1wt%.

[0105] In some embodiments, the Na content in the carbonaceous material may be ≤0.0164wt%, and optionally ≤0.005wt%.

[0106] In some embodiments, in the Raman spectrum of the carbonaceous material, I d / I g The value is 0.90-1.25, I d This indicates that the Raman displacement is within 1350 ± 50 cm. -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 0.90, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, or higher. Optionally, I d / I g It can be 1.05-1.15.

[0107] 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 gRemove 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.

[0108] 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 pseudographite 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 0.90-1.25. At this value, the degree of order in the carbonaceous material structure is moderate, which results in higher capacity and higher first coulombic efficiency, as well as good rate performance.

[0109] 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.

[0110] 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°.

[0111] 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 testing instrument can be a Bruker D8 Discover X-ray diffractometer.

[0112] In some embodiments, the volumetric particle size Dv50 of the carbonaceous material is 3μm-15μm, and can be selected as 4μm-6μm.

[0113] In some embodiments, the volumetric particle size Dv90 of the carbonaceous material is 8μm-30μm, and can be selected as 9μm-12μm.

[0114] In some embodiments, the volumetric particle size Dv50 of the carbonaceous material is 3 μm-15 μm and the volumetric particle size Dv90 is 8 μm-30 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.

[0115] 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.

[0116] 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 / T19077-2016 Particle Size Distribution Laser Diffraction Method. The testing instrument can be a Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK.

[0117] In some embodiments, the specific surface area of ​​the carbonaceous material is 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.

[0118] 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 / T19587-2017 and calculated using the BET (Brunauer Emmett Teller) method. The nitrogen adsorption specific surface area analysis can be performed using the ASAP3020 surface area and pore size analyzer from Micromeritics, Inc., USA.

[0119] 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.

[0120] 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., a UTM7305 model) in accordance with standard 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.

[0121] 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 -0.9g / 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.

[0122] 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, referring to GB / T5162-2006. The testing instrument can be the Dandong Baite BT-301.

[0123] Method for producing a carbonaceous material

[0124] The second aspect of this application provides a method for preparing carbonaceous materials, comprising the following steps: S10, providing raw materials: the raw materials are organic carbon sources; S20, crushing treatment: crushing the raw materials; 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, low-temperature pre-carbonization treatment: placing the washed and impurity-removed raw materials obtained in S30 in a kiln, and heating them to a first temperature T1 at a first rate of ≥20℃ / min under a protective gas atmosphere and a furnace pressure of ≤-2kPa, and then holding them at the first temperature T1 for a first time t1, thereby obtaining preheated decarbonized materials; S50, high-temperature carbonization treatment: placing the preheated decarbonized materials obtained in S40 in a kiln, and heating them to a first temperature T1 at a first rate of ≥20℃ / min under a protective gas atmosphere and a furnace pressure of ≤-2kPa, and a packing density of ≤0.6g / cm³. 3 Under the conditions described, the temperature is increased to a second temperature T2 at a second rate, and then held at the second temperature T2 for a second time t2. After the holding time is completed, a carbonaceous material is obtained. The carbonaceous material, in a CO2 adsorption test, at 0°C and a relative pressure P / P0 of 10... -8 The total CO2 adsorption amount between 0.029 and 0.029 is denoted as A, and the adsorption time is denoted as B. The carbonaceous material satisfies the following condition: A / B ≥ 1.7 cm⁻¹. 3 / (g×h)STP, where STP represents standard conditions, P represents the test pressure of CO2, and P0 represents the saturated vapor pressure of CO2 at 0℃.

[0125] The method for preparing carbonaceous materials in this application includes a crushing process, a washing and impurity removal process, a low-temperature pre-carbonization process, and a high-temperature carbonization process.

[0126] 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-15μm, optionally 4μm-6μm. In some embodiments, the volumetric particle size Dv90 of the crushed particles is 8μm-30μm, optionally 9μm-12μm. In some embodiments, the volumetric particle size Dv50 of the crushed particles is 3μm-15μm and the volumetric particle size Dv90 is 8μm-30μm; optionally, the volumetric particle size Dv50 of the crushed particles is 4μm-6μm and the volumetric particle size Dv90 is 9μm-12μm.

[0127] Washing and impurity removal processes can remove inorganic and water-soluble impurities from raw materials, preventing metal impurities from being reduced to elemental metals and then agglomerating during subsequent high-temperature carbonization. This is because the agglomeration of elemental metals leads to the collapse of the carbon skeleton structure, especially the microporous and / or small mesoporous structures. This results in a reduction in the active ion storage space and capacity of the obtained carbonaceous material. Consequently, the carbonaceous material reaches adsorption equilibrium more quickly, and the CO2 adsorption rate slows down. Metal impurities also have catalytic activity, which intensifies the decomposition of the carbon skeleton structure during thermal decomposition, causing the pore structure to tend towards larger mesoporous and / or macroporous structures. This leads to an increase in the 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. Furthermore, the volume shrinkage of the collapsed carbon skeleton structure also increases the true density of the carbonaceous material. The washing and impurity removal process includes at least an acidic solution washing step and an alkaline solution washing step. The acidic solution is mainly used to remove metallic impurities from the raw materials, while the alkaline solution is mainly used to remove Si-containing impurities from the raw materials that cannot react with acid, thereby ensuring the thorough removal of impurities.

[0128] The crushing process must be carried out 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 raw material particles and the washing liquid and improving the impurity removal effect. If the crushing process is carried out after the washing and impurity removal process, the washing liquid may not be able to penetrate the bulk phase of large raw material particles, thus failing to remove deeply encapsulated impurities within the bulk phase, resulting in poor impurity removal. During subsequent low-temperature pre-carbonization and high-temperature carbonization processes, unremoved metallic impurities, after being reduced to elemental metals, tend to agglomerate, causing the carbon skeleton structure to collapse. This reduces the active ion storage space of the obtained carbonaceous material. Furthermore, the collapse of the carbon skeleton structure leads to discontinuous pore structures, with some pores unable to store active ions, resulting in a decrease in the capacity of the obtained carbonaceous material. In this case, the carbonaceous material reaches adsorption equilibrium in a shorter time, and the CO2 adsorption rate slows down. Unremoved metallic impurities also possess catalytic activity, which will intensify the decomposition of the carbon framework structure during thermal cracking, causing the pore structure to tend towards larger mesoporous and / or macroporous structures. This results in an increased proportion of the electrolyte wetting region within the obtained carbonaceous material, increased consumption of active ions during SEI film formation, increased initial irreversible capacity loss, and decreased initial coulombic efficiency. Furthermore, the volume shrinkage after the collapse of the carbon framework structure will also lead to an increase in the true density of the carbonaceous material.

[0129] Low-temperature pre-carbonization helps form a permeable pore structure, providing rapid escape channels. During low-temperature pre-carbonization, numerous covalent bonds between C, H, and O atoms break, constructing permeable channels within the carbon framework. This provides pathways for the escape of gases generated during the subsequent high-temperature carbonization process, preventing them from clogging the particles and causing secondary carbon formation that would block the pore structure. It also prevents the collapse of the carbon framework structure and pore blockage caused by the rapid H2 impact from CH breakage near 700℃-800℃ during high-temperature carbonization. This avoids problems such as reduced active ion storage space and decreased space utilization in the resulting carbonaceous material. Furthermore, the collapse of the carbon framework and pore blockage increase the difficulty of active ion extraction and the true density of the carbonaceous material.

[0130] During low-temperature pre-carbonization, the temperature is increased at a rate of ≥20℃ / min. If the heating rate is too slow, the resulting carbon framework structure will not be fully adjusted, leading to smaller and discontinuous pore structures that are insufficient to form a continuous gas escape channel. This, in turn, makes the pore structure prone to blockage during subsequent high-temperature carbonization, reducing the active ion storage space of the obtained carbonaceous material, decreasing the space utilization rate, and reducing the capacity. At this point, the carbonaceous material reaches adsorption equilibrium in a shorter time, and the CO2 adsorption rate slows down.

[0131] The furnace pressure during both low-temperature pre-carbonization and high-temperature carbonization is ≤-2 kPa. During the research process, the inventors of this application unexpectedly discovered that the furnace pressure during both low-temperature pre-carbonization and high-temperature carbonization affects the performance of the final carbonaceous material. If the furnace pressure is too high during low-temperature pre-carbonization, the gaseous small molecules released by thermal decomposition 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 thermal decomposition, thus blocking the pore structure and failing to provide sufficient gas escape channels for high-temperature carbonization. Furthermore, during high-temperature carbonization, the gaseous small molecules released by thermal decomposition block the interior of the particles and undergo secondary decomposition to form carbon, further blocking the pore structure. This reduces the active ion storage space of the obtained carbonaceous material, decreases the space utilization rate, and reduces its capacity. In this case, the carbonaceous material reaches adsorption equilibrium in a shorter time, and the CO2 adsorption rate slows down. If the furnace pressure is too high during high-temperature carbonization, the gaseous small molecules released by thermal decomposition will not be able to escape from the particulate phase to the outside in time. Instead, these gaseous small molecules will be bound in the particulate phase and converted into carbon through further thermal decomposition, blocking the pore structure. This will reduce the active ion storage space of the obtained carbonaceous material, decrease the space utilization rate, and reduce the capacity.

[0132] The packing density during high-temperature carbonization treatment is ≤0.6 g / cm³. 3 During their research, the inventors of this application unexpectedly discovered that the packing density of the material during high-temperature carbonization also affects the performance of the final carbonaceous material. If the packing density is too high, the materials will be packed too tightly, blocking the gas escape channels. Some of the blocked gaseous small molecules will decompose again upon heating, transforming into carbon and adhering to the surface of the carbonaceous material. This prevents active ions from smoothly entering the pore structure, thus reducing the availability of the pore structure and decreasing the capacity of the carbonaceous material. In this case, the carbonaceous material reaches adsorption equilibrium in a shorter time, and the CO2 adsorption rate slows down. Furthermore, the accumulation of carbon formed by thermal decomposition on the surface of the obtained carbonaceous material particles increases the difficulty of active ion extraction, leading to a decrease in the initial coulombic efficiency of the carbonaceous material. The higher density of the carbon formed by thermal decomposition also increases the true density of the carbonaceous material.

[0133] Therefore, the carbonaceous material obtained by the preparation method provided in this application has a large amount of active ion storage space and a high space utilization rate, which enables the carbonaceous material to achieve both high capacity and first coulombic efficiency, and also enables the secondary battery to have high energy density, long service life and good rate performance.

[0134] 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 is simple and 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.

[0135] 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, in S10, the organic carbon source may also include only biomass materials.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] In some embodiments, in S30, the washing temperature of the acidic solution is 10°C-95°C, optionally 30°C-95°C.

[0143] In some embodiments, in S30, the washing time of the acidic solution is 1h-24h, optionally 10h-24h.

[0144] 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 is water. This ensures the thorough removal of metallic impurities while preventing the introduction of other impurity elements.

[0145] 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.

[0146] 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.

[0147] In some embodiments, in S30, the washing temperature of the alkaline solution is 10°C-95°C, optionally 30°C-95°C.

[0148] In some embodiments, in S30, the washing time of the alkaline solution is 1h-24h, optionally 10h-24h.

[0149] In some embodiments, in S30, the solute of the alkaline solution includes NaOH, KOH, or a combination thereof, and the solvent is water. This ensures the thorough removal of impurities such as Si while preventing the introduction of other impurity elements.

[0150] 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.

[0151] In some embodiments, in S40, the first rate can be 20℃ / min-35℃ / min, optionally 25℃ / min-30℃ / min. This is beneficial for carbonaceous materials to better balance high capacity and initial coulombic efficiency. If the heating rate is too fast during low-temperature pre-carbonization treatment, it can easily lead to the equipment temperature control running out of control and exceeding the set holding temperature. When the material is above the first temperature T1, it will undergo rapid decomposition. At this time, the stability of the carbon skeleton structure deteriorates, and the microporous structure and / or small mesoporous structure may collapse, resulting in a reduction in the active ion storage space of the obtained carbonaceous material and a decrease in capacity. In this case, the carbonaceous material reaches adsorption equilibrium in a relatively short time. At the same time, the collapse can also cause some pore structures to merge and introduce larger pore structures, thereby increasing the proportion of the electrolyte wetting area inside the obtained carbonaceous material, increasing the consumption of active ions by SEI film formation, increasing the initial irreversible capacity loss, and reducing the initial coulombic efficiency. In this case, the carbonaceous material exhibits a high true density.

[0152] In some embodiments, in S40, the protective gas may include nitrogen, argon, helium, or a combination thereof.

[0153] In some embodiments, in S40, the furnace pressure can be -5 kPa to -2 kPa, and optionally -4.5 kPa to -3 kPa. This helps ensure safe production. If the furnace pressure is too low, the powder will float and disperse into the furnace under negative pressure, contaminating the furnace and reducing product yield; it also easily leads to dust and protective gas entering the exhaust gas pipe simultaneously, increasing the risk of dust explosion.

[0154] In some embodiments, in S40, the first temperature T1 can be 300°C-600°C, for example, it can be a range of any values ​​including 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, or higher. Optionally, the first temperature T1 is 400°C-500°C. When the first temperature T1 is within a suitable range, it is beneficial to form a through-hole structure, providing a rapid dissipation channel.

[0155] If the initial temperature T1 is too high, the carbon framework structure will not have sufficient time to stabilize, resulting in insufficient strength. During subsequent high-temperature carbonization, the H2 generated in a short time near 700℃-800℃ due to CH4 breakage violently impacts the carbon framework structure, causing it to collapse and block the pores. This reduces the active ion storage space of the obtained carbonaceous material, decreases its usability, and reduces its capacity. At this point, the carbonaceous material reaches adsorption equilibrium in a shorter time, and the CO2 adsorption rate slows down.

[0156] When the initial temperature T1 is too low, the covalent bonds between C, H, and O atoms remain relatively stable, making it impossible to construct a continuous channel structure within the carbon framework. During subsequent high-temperature carbonization, the H2 generated in a short period near 700℃-800℃ due to CH breaking violently impacts the carbon framework, causing it to collapse and block the pores. This reduces the active ion storage space, decreases space utilization, and reduces capacity. Consequently, the carbon material reaches adsorption equilibrium quickly, and the CO2 adsorption rate slows down. Furthermore, the volume shrinkage after the carbon framework collapses also leads to an increase in the true density of the carbon material.

[0157] In some embodiments, in S40, the first time t1 is 1h-24h, for example, it can be 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, or any range of the above values. Optionally, the first time t1 is 6h-12h. Those skilled in the art can select a suitable first time within the above range based on the first temperature used; for example, when the first temperature is high, the first time can be appropriately shortened.

[0158] In some embodiments, in S50, the second rate can be 1℃ / min-10℃ / min, for example 1℃ / min-8℃ / min, 1℃ / min-5℃ / min, or 3℃ / min-5℃ / min. This is beneficial for improving the capacity and / or initial coulombic efficiency of carbonaceous materials. During high-temperature carbonization, if the heating rate is too fast, the gaseous small molecules released during the preheating and decomposition of carbon cannot escape from the particulate phase to the surface in time and then be conducted into the furnace and discharged with the help of the furnace protective gas. Instead, these gaseous small molecules will be bound in the particulate phase and converted into carbon through re-pyrolysis, 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. At this time, the carbonaceous material reaches adsorption equilibrium in a shorter time, and the CO2 adsorption rate slows down. Furthermore, if the heating rate is too fast, gaseous small molecules that do not have time to escape to the outside will impact the carbon skeleton structure, causing the carbon skeleton structure to collapse. This results in an increase in the proportion of the electrolyte wetting area inside the carbon material, an increase in the consumption of active ions by the SEI film formation, an increase in the first irreversible capacity loss, and a decrease in the first coulombic efficiency. At this time, the carbon material exhibits a high true density.

[0159] In some embodiments, in S50, the protective gas may include nitrogen, argon, helium, or a combination thereof.

[0160] In some embodiments, in S50, the furnace pressure can be -5 kPa to -2 kPa, and optionally -4.5 kPa to -3 kPa. This helps ensure safe production. During the high-temperature carbonization process, if the furnace pressure is too low, powder will float and disperse into the furnace under negative pressure, contaminating the furnace and reducing product yield; it also easily leads to dust and protective gas entering the exhaust gas pipe simultaneously, increasing the risk of dust explosion.

[0161] In some embodiments, in S50, the second temperature T2 can be 1000℃-1600℃, for example, it can be a range consisting of 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃, 1500℃, 1550℃, 1600℃ or any value above. Optionally, the second temperature T2 is 1200℃-1400℃. When the second temperature T2 is within a suitable range, it can create a closed-pore effect on the preheated decomposed carbon obtained by low-temperature precarbonization treatment, thereby reducing the contact area between the carbon material and the electrolyte, that is, reducing the consumption of active ions by the SEI film formation and improving the first coulombic efficiency of the carbon material; it can also cause the preheated decomposed carbon obtained by low-temperature precarbonization treatment to undergo aromatic cyclization, thereby improving the order and conductivity of the carbon material, while removing excess O and H elements from the carbon skeleton structure, and helping to form an ordered pseudo-graphite microcrystalline structure.

[0162] When the second temperature T2 is too high, the pseudo-graphite microcrystalline structure fuses extensively under high energy conditions. This leads to an increase in the size and a decrease in the number of pores in the resulting carbonaceous material, resulting in reduced active ion storage space and decreased capacity. In this case, the carbonaceous material reaches adsorption equilibrium in a shorter time. Simultaneously, it also reduces the interlayer spacing of the carbonaceous material, increasing the difficulty of active ion insertion and extraction, lowering the initial coulombic efficiency, and increasing the density of the carbon framework structure. In this case, the carbonaceous material exhibits a slower CO2 adsorption rate. When the second temperature T2 is too low, a large amount of unstable carbon remains in the carbon framework structure, resulting in fewer pores formed in the carbonaceous material, reduced active ion storage space, and decreased capacity. In this case, the carbonaceous material reaches adsorption equilibrium in a shorter time. Furthermore, at a low second temperature T2, a large amount of oxygen may remain. Since oxygen atoms cannot reversibly intercalate and deintercalate with active ions, this further reduces the capacity and initial coulombic efficiency of the carbonaceous material.

[0163] In some embodiments, in S50, the second time t1 can be 1h-24h, for example, it can be a range of 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, or any of the above values. Optionally, the second time t1 is 6h-12h. Those skilled in the art can select a suitable second time within the above range according to the second temperature used; for example, when the second temperature is high, the second time can be appropriately shortened.

[0164] In some embodiments, the preparation method further includes: S60, secondary crushing treatment: crushing the carbonaceous material obtained in S50. At this time, some agglomerated carbonaceous material can be crushed to meet the required particle size, which is convenient for preparing negative electrode slurry and negative electrode sheet. Of course, in some embodiments, this step can be omitted.

[0165] 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; S30, washing and removing impurities treatment: washing and removing impurities from the crushed raw materials obtained in S20, wherein the washing and removing impurities treatment process includes at least an acidic solution washing step and an alkaline solution washing step; S40, low-temperature pre-carbonization treatment: placing the washed and removed impurities raw materials obtained in S30 in a kiln, under a protective gas atmosphere and a furnace pressure of [missing information]. Under conditions of ≤-2kPa (optionally -5kPa to -2kPa), the temperature is increased to 300℃-600℃ at a first rate of ≥20℃ / min (optionally 20℃ / min-35℃ / min), and then held at this temperature for 1h-24h to obtain preheated decarbonized carbon; S50, high-temperature carbonization treatment: the preheated decarbonized carbon obtained in S40 is placed in a kiln under a protective gas atmosphere, a furnace pressure of ≤-2kPa (optionally -5kPa to -2kPa), and a packing density of ≤0.6g / cm³. 3 Under these conditions, the temperature is increased to 1000℃-1600℃ at a second rate, and then held at this temperature for 1h-24h. The resulting carbonaceous material exhibits good performance in CO2 adsorption tests at 0℃ and a relative pressure P / P0 of 10. -8 The total CO2 adsorption amount between 0.029 and 0.029 is denoted as A, and the adsorption time is denoted as B. The carbonaceous material satisfies the following condition: A / B ≥ 1.7 cm⁻¹. 3 / (g×h)STP, where STP represents standard conditions, P represents the test pressure of CO2, and P0 represents the saturated vapor pressure of CO2 at 0°C. This allows carbonaceous materials to achieve higher capacity and initial coulombic efficiency, and further improves the energy density, lifespan, and rate performance of secondary batteries.

[0166] Secondary battery

[0167] The third aspect of this application provides a secondary battery.

[0168] 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.

[0169] 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).

[0170] 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.

[0171] 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.

[0172] 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.

[0173] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0174] 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.

[0175] [Negative electrode plate]

[0176] 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.

[0177] 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 enables the secondary battery to simultaneously possess high energy density, long lifespan, and good rate performance.

[0178] 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.

[0179] 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.

[0180] 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).

[0181] 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.

[0182] 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).

[0183] 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.

[0184] 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.

[0185] [Positive electrode plate]

[0186] 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.

[0187] 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).

[0188] 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 this. 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.

[0189] The positive electrode active material may be a positive electrode active material known in the art for use in secondary batteries.

[0190] 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.

[0191] 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 Nib 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] [Electrolytes]

[0197] 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).

[0198] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0199] The type of electrolyte salt is not specifically limited and can be selected according to actual needs.

[0200] 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).

[0201] 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).

[0202] 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).

[0203] 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.

[0204] [Isolation membrane]

[0205] 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.

[0206] 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.

[0207] [Preparation Method]

[0208] 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.

[0209] Electricity-using device

[0210] 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.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] Example

[0215] 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.

[0216] Example 1

[0217] 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, it was dried by forced air to remove moisture. The dried powder was placed in a kiln and heated to 400 °C at a rate of 30 °C / min under a nitrogen atmosphere and a furnace pressure of -5 kPa, and held at that temperature for 10 h. Afterward, it was treated under a nitrogen atmosphere, a furnace pressure of -5 kPa, and a packing density of 0.3 g / cm³. 3 Under the conditions, the temperature was increased to 1400℃ at a rate of 5℃ / min and then held for 10 hours to obtain carbonaceous material.

[0218] Referring to GB / T21650.2-2008, CO2 adsorption tests were conducted on carbonaceous materials at 0℃, and the relative pressure P / P0 was recorded within a range of 10. -8 The total CO2 adsorption amount A and adsorption time B are between 0.029 and 0.029, where P represents the test pressure of CO2 and P0 represents the saturated vapor pressure of CO2 at 0°C. The testing instrument can be a Micromeritics ASAP2460 surface area and pore size analyzer.

[0219] The true density of carbonaceous materials was tested using the Archimedes impregnation volume displacement method with n-butanol as the medium.

[0220] Examples 2-16 and Comparative Examples 1-7

[0221] 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.

[0222] Comparative Example 8

[0223] Commercially available coconut shells were crushed using an air jet mill to a volumetric particle size (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, and then dried by forced air to remove moisture. The dried powder was placed in a kiln and heated to 400°C at a rate of 30°C / min under a nitrogen atmosphere and a furnace pressure of -5 kPa, and held at that temperature for 10 h. Afterwards, the powder was further treated under a nitrogen atmosphere, a furnace pressure of -5 kPa, and a packing density of 0.3 g / cm³. 3 Under the conditions, the temperature was increased to 1400℃ at a rate of 5℃ / min and then held for 10 hours to obtain carbonaceous material.

[0224] Comparative Example 9

[0225] 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 400°C at a rate of 30°C / min under a nitrogen atmosphere and a furnace pressure of -5 kPa, and held at that temperature for 10 h. Afterward, the powder was further treated under a nitrogen atmosphere, a furnace pressure of -5 kPa, and a packing density of 0.3 g / cm³. 3 Under the conditions, the temperature was increased to 1400℃ at a rate of 5℃ / min and then held for 10 hours to obtain carbonaceous material.

[0226] Comparative Example 10

[0227] Commercially available coconut shells were crushed using an air jet mill to a volumetric particle size (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 400°C at a rate of 30°C / min under a nitrogen atmosphere and a furnace pressure of -5 kPa, followed by a holding time of 10 hours. Afterward, the mixture was treated under a nitrogen atmosphere, a furnace pressure of -5 kPa, and a packing density of 0.3 g / cm³. 3 Under the conditions, the temperature was increased to 1400℃ at a rate of 5℃ / min and then held for 10 hours to obtain carbonaceous material.

[0228] Comparative Example 11

[0229] Commercially available coconut shells were crushed using an air jet mill to a volumetric 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 400 °C at a rate of 30 °C / min under a nitrogen atmosphere and a furnace pressure of -5 kPa, followed by a holding time of 10 h. Afterward, the mixture was treated under a nitrogen atmosphere, a furnace pressure of -5 kPa, and a packing density of 0.3 g / cm³. 3Under the conditions, the temperature was raised to 1400℃ at a rate of 5℃ / min and held for 10h. Then, it was washed with 3mol / L perchloric acid aqueous solution at 60℃ for 12h, followed by washing with deionized water until neutral, and finally dried by blowing to remove moisture to obtain carbonaceous material.

[0230] Comparative Example 12

[0231] Commercially available coconut shells were washed with a 3 mol / L perchloric acid aqueous solution at 60°C for 12 h, followed by washing with deionized water until neutral. Then, they were washed with a 3 mol / L NaOH aqueous solution at 95°C for 24 h, and again with deionized water until neutral. The mixture was then dried by forced air to remove moisture, and finally 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 resulting powder was placed in a kiln and heated to 400°C at a rate of 30°C / min under a nitrogen atmosphere and a furnace pressure of -5 kPa, and held at that temperature for 10 h. Afterward, the mixture was further treated under a nitrogen atmosphere, a furnace pressure of -5 kPa, and a packing density of 0.3 g / cm³. 3 Under the conditions, the temperature was increased to 1400℃ at a rate of 5℃ / min and then held for 10 hours to obtain carbonaceous material.

[0232] Comparative Example 13

[0233] 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, it was dried by forced air to remove moisture. The dried powder was then placed in a kiln under a nitrogen atmosphere, a furnace pressure of -5 kPa, and a packing density of 0.3 g / cm³. 3 Under the conditions, the temperature was increased to 1400℃ at a rate of 5℃ / min and then held for 10 hours to obtain carbonaceous material.

[0234] Performance test

[0235] 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.

[0236] 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.

[0237] The reversible specific capacity (mAh / g) of carbonaceous material = the first charge capacity of the coin cell / the mass of the carbonaceous material.

[0238] The initial coulombic efficiency (%) of carbonaceous materials = the first charge capacity of the coin cell / the first discharge capacity of the coin cell × 100%.

[0239] Based on the test results in Table 1, it can be seen that when carbonaceous materials are tested for CO2 adsorption at 0℃ and with a relative pressure P / P0 of 10, the optimal performance is achieved. -8 The total CO2 adsorption amount between 0 and 0.029 is denoted as A, and the CO2 adsorption time B satisfies: A / B ≥ 1.7 cm⁻¹ 3 / (g×h)STP, can be selected as ≥3.0cm 3 When the STP value is / (g×h), a value of ≥8.0cm can be selected. 3 At / (g×h)STP, carbonaceous materials can achieve both high capacity and first coulombic efficiency.

[0240] The carbonaceous materials prepared in Comparative Examples 1-13 showed good performance in CO2 adsorption tests at 0°C and with a relative pressure P / P0 of 10. -8 The total CO2 adsorption amount between 0.029 and 0.029 is denoted as A. Neither A nor B satisfies the condition that A / B ≥ 1.7 cm⁻¹. 3 / (g×h)STP, and neither can enable carbonaceous materials to achieve both high capacity and first coulombic efficiency.

[0241] Figure 7 and Figure 8This is a CO2 adsorption test curve of the carbonaceous material prepared in Example 1. Figure 9 and Figure 10 This is a CO2 adsorption test curve of the carbonaceous material prepared in Comparative Example 1. As shown in Table 1, compared with Comparative Example 1, the capacity and initial coulombic efficiency of the carbonaceous material prepared in Example 1 are significantly improved. This may be because the carbonaceous material prepared in Example 1 has more active ion storage space and higher space utilization, thus facilitating the insertion, storage, and extraction of active ions.

[0242] The test results from Examples 1-16 also show that when the CO2 adsorption time B further satisfies B≥5h, and can be selected as ≥7h, the carbonaceous material can have higher capacity and initial coulombic efficiency.

[0243] 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.

[0244]

[0245]

Claims

1. A carbonaceous material, wherein, The carbonaceous material performed well in the CO2 adsorption test at 0°C and a relative pressure P / P0 of 10. -8 The total CO2 adsorption amount between 0 and 0.029 is denoted as A, and the adsorption time is denoted as B. The carbonaceous material satisfies: A / B≥1.7 cm³ / (g×h) STP, where STP is the standard condition, P represents the test pressure of CO2, and P0 represents the saturated vapor pressure of CO2 at 0℃.

2. The carbonaceous material according to claim 1, wherein, 1.7 cm³ / (g×h)STP≤A / B≤20 cm³ / (g×h)STP.

3. The carbonaceous material according to claim 2, wherein, 3.0 cm³ / (g×h)STP≤A / B≤20 cm³ / (g×h)STP.

4. The carbonaceous material according to any one of claims 1-3, wherein, B≥5h.

5. The carbonaceous material according to claim 4, wherein, 5h≤B≤10h.

6. The carbonaceous material according to any one of claims 1-5, wherein, A≥10 cm³ / g STP.

7. The carbonaceous material according to claim 6, wherein, 15 cm³ / g STP≤A≤200 cm³ / g STP.

8. The carbonaceous material according to any one of claims 1-7, wherein, The true density ρ of the carbonaceous material is ≤1.45 g / cm³. 3 .

9. The carbonaceous material according to claim 8, wherein, The true density ρ of the carbonaceous material is 1.0 g / cm³. 3 -1.45g / cm 3 .

10. The carbonaceous material according to any one of claims 1-9, wherein, The carbonaceous material includes multiple nanoporous structures.

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

12. The carbonaceous material according to any one of claims 1-11, wherein, In the Raman spectrum of the carbonaceous material, I d / I g The value is 0.90-1.25, I d This indicates that the Raman displacement is within 1350 ± 50 cm. -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°.

13. The carbonaceous material according to claim 12, wherein, I d / I g is 1.05 - 1.

15.

14. The carbonaceous material according to claim 12, wherein, The interlayer spacing of the (002) crystal plane of the carbonaceous material is 0.37nm-0.42nm.

15. The carbonaceous material according to any one of claims 1-14, 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-15μm; (2) The volumetric particle size Dv90 of the carbonaceous material is 8μm-30μm; (3) The specific surface area of ​​the carbonaceous material is 1m². 2 / g-10m 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 .

16. The carbonaceous material according to claim 15, 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 4μm-6μm; (2) The volumetric particle size Dv90 of the carbonaceous material is 9μm-12μm; (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 0.93 g / cm³. 3 -1.02g / cm 3 ; (5) The tap density of the carbonaceous material is 0.85 g / cm³. 3 -0.9g / cm 3 .

17. A method for preparing a carbonaceous material, comprising the following steps: S10, Providing raw materials: The raw materials are organic carbon sources; S20, Crushing process: The raw material is crushed. S30, washing and impurity removal treatment; The crushed raw material obtained in S20 is washed and impurities are removed. The washing and impurity removal process includes at least an acidic solution washing step and an alkaline solution washing step. S40, Low-temperature pre-carbonization treatment: The raw material obtained by S30 after washing and removing impurities is placed in a kiln. Under the conditions of protective gas atmosphere and furnace pressure of ≤-2kPa, the temperature is raised to the first temperature T1 at the first rate of ≥20℃ / min. Then, it is held at the first temperature T1 for a first time t1. After the treatment, preheated decarbonization is obtained. S50, high-temperature carbonization treatment: The preheated decomposed carbon obtained from S40 is placed in a kiln under a protective gas atmosphere, with a furnace pressure of ≤-2kPa and a packing density of ≤0.6g / cm³. 3 Under the conditions described, the temperature is increased to a second temperature T2 at a second rate, and then held at the second temperature T2 for a second time t2. After the holding time is completed, a carbonaceous material is obtained. The carbonaceous material, in a CO2 adsorption test, at 0°C and a relative pressure P / P0 of 10... -8 The total CO2 adsorption amount between 0 and 0.029 is denoted as A, and the adsorption time is denoted as B. The carbonaceous material satisfies: A / B≥1.7 cm³ / (g×h) STP, where STP is the standard condition, P represents the test pressure of CO2, and P0 represents the saturated vapor pressure of CO2 at 0℃.

18. The method according to claim 17, wherein, In S10, the organic carbon source includes one or more of biomass materials and thermoplastic resin materials.

19. The method according to claim 18, wherein, The biomass materials include one or more of energy crops and biomass waste.

20. The method according to claim 18, 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.

21. The method according to any one of claims 17-20, 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 sequentially includes the following steps: alkaline solution washing, water washing, acidic solution washing, water washing, and drying.

22. The method according to any one of claims 17-21, 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 is water.

23. The method according to claim 22, wherein, The acidic solution has H + The concentration is 1 mol / L to 6 mol / L.

24. The method according to claim 22, wherein, The washing temperature of the acidic solution is 30℃-95℃.

25. The method according to claim 22, wherein, The washing time with the acidic solution is 10h-24h.

26. The method according to any one of claims 17-25, 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 is water.

27. The method according to claim 26, wherein, The alkaline solution contains OH- - The concentration is 1 mol / L to 6 mol / L.

28. The method according to claim 26, wherein, The washing temperature of the alkaline solution is 30℃-95℃.

29. The method according to claim 26, wherein, The washing time with the alkaline solution is 10h-24h.

30. The method according to any one of claims 17-29, wherein, In S40, the temperature T1 is 300℃-600℃; and / or, In S40, the time t1 is 1h-24h; and / or, In S40, the first rate is 20°C / min - 35°C / min; and / or, In S40, the protective gas includes nitrogen, argon, helium, or a combination thereof; and / or, In S40, the furnace pressure is -5 kPa to -2 kPa.

31. The method according to claim 30, wherein, In S40, the temperature T1 is 400℃-500℃.

32. The method according to claim 30, wherein, In S40, the time t1 is 6h-12h.

33. The method according to claim 30, wherein, In S40, the first rate is 25°C / min-30°C / min.

34. The method according to claim 30, wherein, In S40, the furnace pressure is -4.5 kPa to -3 kPa.

35. The method according to any one of claims 17-34, wherein, In S50, the temperature T2 is 1000℃-1600℃; and / or, In S50, the time t1 is 1h-24h; and / or, In S50, the second rate is 1°C / min - 10°C / min; and / or, In S50, the protective gas includes nitrogen, argon, helium, or a combination thereof; and / or, In S50, the furnace pressure is -5 kPa to -2 kPa.

36. The method according to claim 35, wherein, In S50, the temperature T2 is 1200℃-1400℃.

37. The method of claim 35, wherein, In S50, the time t1 is 6h-12h.

38. The method according to claim 35, wherein, In S50, the second rate is 3°C / min - 5°C / min.

39. The method according to claim 35, wherein, In S50, the furnace pressure is -4.5 kPa to -3 kPa.

40. A secondary battery, comprising a negative electrode, said negative electrode comprising the carbonaceous material according to any one of claims 1-16 or the carbonaceous material prepared by the method according to any one of claims 17-39.

41. An electrical device comprising a secondary battery according to claim 40.

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