Fast-charging energy storage homogenized coke, preparation method and application thereof

Abstract

The application discloses a kind of fast charging energy storage with homogeneous coke, preparation method and application, belong to carbon material preparation field.The fast charging energy storage with homogeneous coke polarizing structure small piece ratio ≥60%, inlay structure ≤10%, sulfur content ≤0.5%, ash ≤0.15%, volatile matter ≤8.0%;The length of the polarizing structure small piece is 10-30 μm, and the width is 10-30 μm;The length of the inlay structure is <10 μm, and the width is <10 μm.The fast charging energy storage with homogeneous coke provided by the application polarizing structure small piece ratio ≥60% and the high-conductivity carbon nanotube existing in system can give graphite negative electrode excellent rate performance and cycle stability, and the capacity attenuation is less than 10% under 6C charging rate current, cycle 500 times.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of carbon material preparation, and particularly relates to a homogeneous coke for fast-charging energy storage, a preparation method and application thereof. BACKGROUND

[0002] The structure stability and ion diffusion rate of the negative electrode material are required to be extremely high for fast-charging lithium ion batteries. The traditional needle coke has a directional arrangement structure, mainly a fiber structure, a large microcrystalline size, and a long lithium ion diffusion path. Under the condition of large-rate charging and discharging, the interlayer stress generated when lithium ions are embedded and extracted will cause the graphite layer to peel off and the negative electrode structure to collapse under a long cycle, which is manifested as capacity attenuation.

[0003] In order to cope with the above problems, improve the fast-charging performance, and enhance the cycle stability, researchers design various customized cokes. The mainstream idea is to reduce the proportion of fiber structure of coke and improve the isotropy:

[0004] Patent CN1306070A places coal tar or petroleum residue distillation liquid in a reactor, heats it to 120℃, stirs and introduces an oxygen-containing gas, the reaction temperature is 260-430℃, after reaching the reaction temperature, constant temperature, the reaction time is 5-15 hours, and the oxidized coal tar or petroleum residue distillation is obtained, and the isotropy is improved by oxidation and crosslinking. Patent CN111943184A uses pitch as raw material, mixes pitch with heavy petroleum components, and sends the mixture into a coking tower for coking to obtain a negative electrode coke with short-range ordered flaky structure. Whether oxidation and crosslinking or direct coking of heavy raw materials, the proportion of fiber structure of the resulting coke is reduced and the isotropy is improved by changing the properties of the raw materials, including hydrocarbon composition or oil slurry molecular structure. However, these schemes also result in a higher proportion of mosaic structure (>30%) in the resulting coke, which is difficult to graphitize, resulting in a lower graphitization degree of the graphitized sample, which in turn affects the capacity, and the capacity is generally lower than 350 mAh / g.

[0005] Patent CN114525153A adds a nucleating agent (finely powdered calcined petroleum coke, pitch coke, petroleum-based needle coke, and coal-based needle coke) to ensure that intermediate phase small spheres are easily generated during preparation, and the fusion between the small spheres is prevented by the addition of the nucleating agent, ensuring that the number of intermediate phase small spheres is large and uniformly distributed, and the isotropy of the coke is improved. This physical mixing scheme can ensure the graphitization degree of the resulting coke, so the capacity is generally greater than 355 mAh / g. However, the compatibility of the solid carbon-based material with the oil slurry is poor, resulting in a low uniformity of the structure of the resulting coke. In addition, the interlayer diffusion form of lithium ions in graphite has not changed, so the performance under the condition of large-rate charging and discharging is still limited. SUMMARY

[0006] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is the poor fast-charging performance of traditional needle coke, and a fast-charging energy storage homogenized coke with excellent graphitization performance, good rate performance and cycle stability, which can be applied to the field of fast-charging energy storage, a preparation method thereof and application thereof are provided.

[0007] To solve the technical problem, the technical scheme adopted by the present application is:

[0008] In one aspect, the present application provides a fast-charging energy storage homogenized coke, wherein the fast-charging energy storage homogenized coke has a polarized structure small piece ratio of ≥60%, an inlaid structure of ≤10%, a sulfur content of ≤0.5%, an ash content of ≤0.15%, and a volatile content of ≤8.0%; the polarized structure small piece has a length of 10-30 μm and a width of 10-30 μm; and the inlaid structure has a length of <10 μm and a width of <10 μm.

[0009] In another aspect, the present application provides a preparation method of the fast-charging energy storage homogenized coke, comprising the following steps:

[0010] S1: mixing carbon nanotubes, a dispersing agent, a surfactant and a dispersing solvent to obtain a homogenized slurry;

[0011] S2: mixing the homogenized slurry and pretreated oil slurry to obtain a reaction raw material, and performing a coking reaction on the reaction raw material to generate a fast-charging energy storage homogenized coke.

[0012] Preferably, in step S2, the oil slurry is one or more of catalytic cracking oil slurry, vacuum residue and backfrying oil;

[0013] The pretreatment process is filtration settlement, catalytic hydrogenation and vacuum fractionation, the filtration settlement controls the oil slurry ash content to be ≤0.15%, the catalytic hydrogenation controls the oil slurry sulfur content to be ≤0.5%, and the vacuum fractionation controls the oil slurry initial boiling point to be ≥250℃.

[0014] Preferably, in step S2, the coking reaction has a reaction temperature of 450-520℃, a reaction pressure of 0.4-1.0 MPa, and a reaction time of 8-24 h.

[0015] Preferably, in step S1, the dispersing solvent is one or more of coking diesel oil, coking wax oil and ethylene tar.

[0016] Preferably, in step S1, the addition amounts of the carbon nanotubes, the dispersing agent and the surfactant are 0.5‰-5%, 0.5-1% and 0.1‰-0.5% of the mass of the homogenized slurry, respectively.

[0017] In step S2, the addition amount of the homogenized slurry is 5%-50% of the mass of the reaction raw material.

[0018] Preferably, in step S1, the dispersant is one or more of polyvinylpyrrolidone, polyethylene glycol, sodium polystyrene sulfonate, polyacrylic acid, polyvinyl alcohol or polyaniline; and the surfactant is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium cholate, sodium deoxycholate or cetyltrimethylammonium bromide.

[0019] In another aspect of the present application, the application of the fast-charging energy storage homogenized coke in the preparation of a lithium ion battery negative electrode material is provided.

[0020] In another aspect of the present application, a lithium ion battery negative electrode material is provided, which comprises the fast-charging energy storage homogenized coke.

[0021] In another aspect of the present application, a lithium ion battery is provided, which comprises a positive electrode, a negative electrode and an electrolyte, wherein the negative electrode comprises the lithium ion battery negative electrode material; and the lithium ion battery has an energy density ≥180 Wh / kg at a 3C rate, and a capacity attenuation <10% after 500 cycles at a 6C rate.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1. The present application provides a fast-charging energy storage homogenized coke, wherein the fast-charging energy storage homogenized coke has a polarized structure small piece ratio ≥60% and high-conductivity carbon nanotubes existing in the system, which can endow the graphite negative electrode with excellent rate performance and cycle stability, and the capacity attenuation is <10% after 500 cycles at a 6C charging rate current.

[0024] 2. The present application provides a preparation method of the fast-charging energy storage homogenized coke, wherein carbon nanotubes are introduced in situ in an oil slurry system, the uniform dispersion of the carbon nanotubes in the system is ensured by a surfactant and a dispersion stabilizer, and the carbon nanotubes are distributed in the oil slurry system by utilizing the high aspect ratio of the carbon nanotubes, which on one hand increases the viscosity of the system and reduces the "pulling coke" effect, and on the other hand hinders the fusion and growth process of the mesophase in the coking process of the oil slurry, thereby reducing the formation of large-size domain structures, so that the coke structure can be controlled, and a coke structure mainly composed of small pieces is formed. Therefore, compared with the needle coke mainly composed of fiber structures, the graphite negative electrode material prepared from the homogenized coke can ensure good cycle stability of the negative electrode; the hollow structure of the carbon nanotubes can provide a fast transmission channel for lithium ions, and the structural defects can provide a path for the diffusion of lithium ions, thereby improving the transmission and diffusion rate of lithium ions. Therefore, compared with the graphite negative electrode material prepared by graphitizing the traditional petroleum coke or needle coke raw material, the graphite negative electrode material prepared from the homogenized coke has higher rate performance. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The polarized structure diagram of the homogenized coke provided by the embodiments of the present application is shown. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the specific implementation manners of the general technical solutions of the present application, but not all the implementation manners. Based on the general concept of the present application, all other embodiments obtained by those skilled in the art fall within the scope of protection of the present application.

[0027] The present application provides a kind of fast charging energy storage with homogeneous coke, fast charging energy storage with homogeneous coke Polarization structure small piece ratio ≥60%, inlay structure ≤10%, sulfur content ≤0.5%, ash ≤0.15%, volatile matter ≤8.0%;The length of the polarization structure small piece is 10-30 μm, and the width is 10-30 μm;The length of the inlay structure is <10 μm, and the width is <10 μm.

[0028] It should be noted that the traditional needle coke has a directional arrangement structure, mainly in the form of fibers, with large crystallite size and long lithium ion diffusion path. Under high-rate charging and discharging conditions, the interlayer stress generated during lithium ion intercalation / deintercalation can cause graphite layer exfoliation and negative electrode structure collapse, resulting in capacity decay.

[0029] To solve the above problems, the present application provides a kind of fast charging energy storage with homogeneous coke, which is different from traditional needle coke. The polarization structure of homogeneous coke is mainly in the form of small pieces, with high isotropy. As a graphite negative electrode material, it has two advantages. Firstly, the high proportion of small piece structure provides more and more uniform "highway entrance and exit" for lithium ions, allowing them to respond faster during high-rate charging and discharging (such as fast charging), exhibit smaller polarization, and thus endow the graphite negative electrode with better rate performance. Secondly, due to its high isotropy, the expansion behavior of homogeneous coke is "dividing the whole into parts", while the expansion of fiber structure is "concentrated". Therefore, homogeneous coke can significantly reduce the expansion rate of the electrode and improve the cycle life and safety of the battery.

[0030] Another aspect of the present application provides a method for preparing the above-mentioned fast charging energy storage with homogeneous coke, comprising the following steps:

[0031] S1: mixing carbon nanotubes, a dispersing agent, a surfactant, and a dispersing solvent to obtain a homogeneous slurry;

[0032] S2: mixing the homogeneous slurry and the pretreated oil slurry to obtain a reaction raw material, and performing a coking reaction on the reaction raw material to generate homogeneous coke.

[0033] In the present application, carbon nanotubes are introduced in-situ in the oil slurry system, and the uniform dispersion of the carbon nanotubes in the system is ensured by surfactants and dispersion stabilizers. The high aspect ratio of the carbon nanotubes is used to "interweave" in the oil slurry system, which on the one hand increases the viscosity of the system and reduces the "charring" effect, and on the other hand hinders the fusion and growth process of the mesophase in the oil slurry coking process, reduces the formation of large size domain structure, so that the coke structure can be controlled, and the coke structure mainly in the form of small pieces is formed. Therefore, compared with needle coke mainly in the form of fiber structure, the graphite negative electrode material prepared by the homogeneous coke can ensure good cycle stability of the negative electrode; the hollow structure of the carbon nanotubes can provide a fast transmission channel for lithium ions, and the structural defects can provide a path for the diffusion of lithium ions, thereby improving the transmission and diffusion rate of lithium ions. Therefore, compared with the graphite negative electrode material prepared by graphitizing the traditional petroleum coke or needle coke raw material, the graphite negative electrode material prepared by the homogeneous coke has higher rate performance.

[0034] In some embodiments, in step S2, the oil slurry is one or more of catalytic cracking oil slurry, vacuum residue, and back-extracted oil;

[0035] The pretreatment process is: filtration settling, catalytic hydrogenation and vacuum fractionation, the filtration settling controls the ash content of the oil slurry to be less than or equal to 0.15%, the catalytic hydrogenation controls the sulfur content of the oil slurry to be less than or equal to 0.5%, and the vacuum fractionation controls the initial boiling point of the oil slurry to be greater than or equal to 250 DEG C.

[0036] The above technical solution limits the type of oil slurry, wherein the catalytic cracking oil slurry is rich in short side chain polycyclic aromatic hydrocarbons, which are basic structural units for forming coke matrix, have high activity, are easy to condense and coke, and provide a large number of cores for forming the required "small piece structure". The aromatic content of the back-extracted oil is higher, and the molecular weight is moderate, which can provide abundant aromatic precursors and uniform composition, which is helpful to promote the uniform generation and development of the intermediate phase in the reaction system and improve the uniformity of the product. The gum and asphaltene content of the vacuum residue is high, which increases the viscosity of the system and physically hinders the excessive growth and fusion of the mesophase spherules, thereby naturally obtaining a small size of flaky optical structure, which forms a synergistic effect with the chemical hindering mechanism of adding CNT.

[0037] The above technical solution also limits the ash content of the pre-processed oil slurry to be less than or equal to 0.15% and the sulfur content to be less than or equal to 0.5%. The reason is that the ash content and S content of green coke will directly affect the electrochemical performance of the graphite negative electrode. High ash content (> 0.15%) is extremely harmful: 1) it destroys the stability of the negative electrode solid electrolyte interface film (SEI film), catalyzes the side reaction, consumes active lithium, and leads to capacity attenuation and reduction of coulombic efficiency; 2) metal impurities may be precipitated during charging and discharging, forming dendrites and causing short circuits in the battery, which poses a serious safety hazard. High sulfur content (> 0.5%) of coke will generate SO2 and other sulfur-containing gases during graphitization, causing environmental pollution and equipment corrosion. In the battery, residual sulfides will dissolve in the electrolyte, destroy the SEI film, increase the interface impedance, and cause serious gas production and self-discharge, leading to battery bulging, shortened cycle life, and deteriorated storage performance.

[0038] In some embodiments, in step S2, the reaction temperature of the coking reaction is 450-520℃, the reaction pressure is 0.4-1.0MPa, and the reaction time is 8-24h.

[0039] The above technical solution defines specific reaction conditions for the coking reaction. If the coking temperature is too low, the green coke will not develop completely, and the green coke will have a high volatile content. High volatile content (> 8%) means that the coking degree is not complete, and a large amount of gas will be generated during subsequent graphitization at high temperature, causing the product to expand, crack, or form a porous structure, reducing its mechanical strength and tap density. This will affect the processing performance of the electrode sheet and may accelerate the capacity decay during the cycle process due to structural defects.

[0040] In some embodiments, in step S1, the dispersing solvent is one or more of coking diesel, coking wax oil, and ethylene tar.

[0041] The above technical solution limits the type of dispersing solvent to one or more of coking diesel, coking wax oil, and ethylene tar. The core advantage of these solvents lies in their rich aromatic hydrocarbon and condensed ring aromatic hydrocarbon composition. The surface of carbon nanotubes (CNT) is a hydrophobic sp2 carbon network, and there is strong π-π conjugation and hydrophobic interaction between these aromatic structures. This molecular-level affinity can effectively overcome the van der Waals force between CNTs, making them more easily infiltrated and dispersed, thereby achieving high concentration and stable dispersion. In addition, as by-products of petroleum refining or ethylene production, their cost is much lower than that of traditional special organic solvents such as N-methyl pyrrolidone (NMP) and dimethylformamide (DMF), which has a huge economic advantage.

[0042] In some embodiments, in step S1, the amounts of carbon nanotubes, dispersant, and surfactant are 0.5‰-5%, 0.5-1%, and 0.1‰-0.5‰, respectively, based on the mass of the homogeneous slurry.

[0043] In step S2, the amount of the homogeneous slurry added is 5%-50% of the mass of the reaction raw materials.

[0044] The above technical solution limits the amount of each reaction raw material, and the most critical is the addition amount of carbon nanotubes (CNT), which must be strictly limited to the optimal interval. The reason is that insufficient addition cannot effectively space limit the growth of the intermediate phase; and excessive addition will cause the CNT to agglomerate due to its strong van der Waals force. In addition, by introducing an appropriate amount of dispersant and surfactant, the uniform dispersion of CNT can be ensured, which is a prerequisite for realizing its function.

[0045] In some embodiments, in step S1, the dispersant is one or more of polyvinylpyrrolidone, polyethylene glycol, sodium polystyrene sulfonate, polyacrylic acid, polyvinyl alcohol, or polyaniline.

[0046] The above technical solution limits the type of dispersant to one or more of polyvinylpyrrolidone, polyethylene glycol, sodium polystyrene sulfonate, polyacrylic acid, polyvinyl alcohol, or polyaniline. The reason is that the dispersant is mainly a high molecular polymer, and its core mechanism for dispersing carbon nanotubes (CNT) is steric hindrance stabilization. The hydrophobic segment of these polymers is adsorbed on the surface of CNT through π-π conjugation, while the hydrophilic segment extends into the solvent to form a coating layer. When two wrapped CNTs approach each other, the overlap of the polymer layer will cause entropy reduction and generate osmotic repulsion, effectively preventing CNT agglomeration.

[0047] In some embodiments, in step S1, the surfactant is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium cholate, sodium deoxycholate, or cetyltrimethylammonium bromide.

[0048] The above technical solution limits the type of dispersant to one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium cholate, sodium deoxycholate, or cetyltrimethylammonium bromide. The reason is that the surfactant is a small molecule amphiphilic compound, and its dispersion of CNT mainly relies on the electrostatic stabilization mechanism. Its hydrophobic tail chain is adsorbed on the surface of CNT, and the hydrophilic ionic head group makes CNT charged, achieving dispersion through the electrostatic repulsion between the double electric layers. Bile salts can also provide significant steric hindrance due to their unique rigid steroidal ring structure.

[0049] In some embodiments, in step S1, the mixing process is ball milling, sand milling, or high-pressure homogenization, and the mixing time is 1-4 h.

[0050] In the technical solution, the ball milling mainly relies on the impact and shearing force of the grinding balls to physically break the CNT agglomerates, and has the advantages of simple equipment, large processing capacity and low cost. The sand milling utilizes the strong shearing and friction force of the rotating grinding medium on the slurry to efficiently strip the CNT bundles, and has the advantages of high dispersion efficiency and uniform particle size, and is suitable for continuous production of medium and low viscosity slurry, and is a common method for preparing conductive slurry. The high-pressure homogenization makes the slurry pass through a narrow gap under high pressure to generate strong shearing force, cavitation effect and impact force, thereby realizing efficient dispersion, and has the advantages of best dispersion effect, high slurry stability and no medium pollution.

[0051] In another aspect of the present application, the application of the fast-charging energy storage homogenized coke in the preparation of a lithium ion battery negative electrode material is provided, and the lithium ion battery is a fast-charging lithium ion battery.

[0052] In another aspect of the present application, a lithium ion battery negative electrode material is provided, which comprises the fast-charging energy storage homogenized coke.

[0053] In another aspect of the present application, a lithium ion battery is provided, which comprises a positive electrode, a negative electrode and an electrolyte, and the negative electrode comprises the lithium ion battery negative electrode material; the lithium ion battery has an energy density≥180 Wh / kg at a 3C rate, and a capacity attenuation<10% after 500 cycles at a 6C rate.

[0054] In order to more clearly and specifically introduce the fast-charging energy storage homogenized coke, the preparation method and the application thereof provided by the embodiments of the present application, the following will be described in combination with specific embodiments.

[0055] In the following examples and comparative examples of the present application, the carbon nanotubes are multi-walled twisted tubes from Hubei Guanyu New Material Technology Co., Ltd., wherein the tube diameter is 10-20 nm, the tube length is 10-30 μm, the specific surface area is 220-280 m 2 / g.

[0056] Example 1

[0057] Preparation of the fast-charging energy storage homogenized coke

[0058] (1) The carbon nanotubes, polyvinylpyrrolidone (dispersant), sodium dodecyl sulfate (surfactant) and coking wax oil (dispersion solvent) are mixed, and after ball milling for 3 hours, ultrasonic treatment is performed to obtain a homogenized slurry;

[0059] The addition amounts of the carbon nanotubes, polyvinylpyrrolidone, sodium dodecyl sulfate and coking wax oil are 1.5‰, 0.8% and 0.3‰ of the mass of the homogenized slurry, respectively;

[0060] (2) The homogenized slurry and the catalytic cracking oil slurry pretreated by filtration and sedimentation, catalytic hydrogenation and vacuum fractionation are mixed by high-speed stirring to obtain a reaction raw material;

[0061] The addition amount of the homogeneous slurry is 20% of the mass of the reaction raw material;

[0062] The specific reaction conditions of the filtration settlement, catalytic hydrogenation, and vacuum fractionation are as follows:

[0063] The filtration settlement operation temperature is maintained at 100°C to reduce the viscosity of the raw material. The specific steps are as follows:

[0064] First, the catalytic cracking oil slurry is allowed to stand and settle in a storage tank for 48 hours to allow most of the particles to be naturally separated under the action of gravity, and then the final purification is performed through a precision filtration system to ensure that the ash content of the finished oil slurry is ≤0.15%.

[0065] The catalytic hydrogenation controls the reaction temperature at 320°C, the system pressure at 10 MPa (high pressure), and uses a Co-Mo catalyst. During the process, a high hydrogen oil ratio (800 Nm 3 / m 3 ) is maintained to ensure the reaction efficiency and heat removal, and a lower volume space velocity (1 h -1 ) is controlled to ensure sufficient reaction contact time, and finally the sulfur content of the oil slurry is stably controlled at ≤0.5%.

[0066] The vacuum fractionation process maintains a high vacuum degree (3 kPa absolute pressure) at the top of the column, and the bottom temperature is controlled at 300°C to avoid cracking and coking. By adjusting the side-line extraction and column reflux ratio, the cut fraction is accurately cut to ensure that the initial boiling point of the target product oil slurry is ≥250°C.

[0067] (3) The reaction raw material is subjected to coking reaction at 480°C and 0.6 MPa for 12 hours to obtain the homogeneous coke for fast charging energy storage.

[0068] Example 2

[0069] Preparation of the homogeneous coke for fast charging energy storage

[0070] (1) Carbon nanotubes, polyethylene glycol (dispersant), sodium dodecyl benzene sulfonate (surfactant), and ethylene tar (dispersion solvent) are mixed, and after 2 hours of high-pressure homogenization, ultrasonic treatment is performed to obtain a homogeneous slurry;

[0071] The addition amounts of carbon nanotubes, polyethylene glycol, and sodium dodecyl benzene sulfonate are 3‰, 0.6%, and 0.2‰ of the mass of the homogeneous slurry, respectively;

[0072] (2) The homogeneous slurry is mixed with the vacuum residue pretreated by filtration settlement, catalytic hydrogenation, and vacuum fractionation to obtain a reaction raw material;

[0073] The addition amount of the homogeneous slurry is 30% of the mass of the reaction raw material;

[0074] The specific reaction conditions of the filtration sedimentation, catalytic hydrogenation and vacuum fractionation are as follows:

[0075] The filtration sedimentation process is basically the same as that in Embodiment 1, except that the standing sedimentation is controlled for 72 hours to ensure that the ash content of the finished oil is ≤0.15%.

[0076] The catalytic hydrogenation process is basically the same as that in Embodiment 1, except that the reaction temperature is controlled at 300°C and the system pressure is 8 MPa, and finally the sulfur content of the oil slurry is stably controlled at ≤0.5%.

[0077] The vacuum fractionation process is basically the same as that in Embodiment 1, except that the bottom temperature is controlled at 280°C to avoid cracking and coking, and ensure that the initial boiling point of the target product oil slurry is ≥250°C.

[0078] (3) The reaction raw material is subjected to coking reaction at 500°C and 0.8 MPa for 10 hours to obtain the homogeneous coke for fast charging energy storage.

[0079] Embodiment 3

[0080] Preparation of homogeneous coke for fast charging energy storage

[0081] (1) The carbon nanotubes, sodium polystyrene sulfonate (dispersant), sodium cholate (surfactant) and coking wax oil (dispersion solvent) are mixed, and after sand milling for 4 hours, ultrasonic treatment is performed to obtain a homogeneous slurry;

[0082] The addition amounts of the carbon nanotubes, sodium polystyrene sulfonate and sodium cholate are 0.5‰, 1% and 0.5‰ of the mass of the homogeneous slurry, respectively;

[0083] (2) The homogeneous slurry is mixed with the reclaimed oil pretreated by filtration sedimentation, catalytic hydrogenation and vacuum fractionation by high-speed stirring to obtain a reaction raw material;

[0084] The addition amount of the homogeneous slurry is 10% of the mass of the reaction raw material;

[0085] The specific reaction conditions of the filtration sedimentation, catalytic hydrogenation and vacuum fractionation are as follows:

[0086] The filtration sedimentation process is the same as that in Embodiment 1;

[0087] The catalytic hydrogenation process is basically the same as that in Embodiment 1, except that the reaction temperature is controlled at 330°C and the system pressure is 12 MPa, and finally the sulfur content of the oil slurry is stably controlled at ≤0.5%.

[0088] The vacuum fractionation process is the same as that in Embodiment 1.

[0089] (3) The reaction raw material is subjected to coking reaction at 460°C and 0.5 MPa for 20 hours to obtain the homogeneous coke for fast charging energy storage.

[0090] Embodiment 4

[0091] Preparation of homogenized coke for fast charging energy storage

[0092] (1) Carbon nanotubes, polyacrylic acid (dispersant), sodium deoxycholate (surfactant), and coking diesel (dispersion solvent) were mixed, ball milled for 2 hours, and then ultrasonically treated to obtain a homogenized slurry;

[0093] The addition amounts of carbon nanotubes, polyacrylic acid, and sodium deoxycholate were 5 ‰, 0.7%, and 0.1 ‰ of the mass of the homogenized slurry, respectively;

[0094] (2) The homogenized slurry was mixed with catalytically cracked oil slurry pretreated by filtration settlement, catalytic hydrogenation, and vacuum distillation at high speed to obtain a reaction raw material;

[0095] The addition amount of the homogenized slurry was 40% of the mass of the reaction raw material;

[0096] Among them, the specific reaction conditions of filtration settlement, catalytic hydrogenation, and vacuum distillation were the same as in Example One:

[0097] (3) The reaction raw material was subjected to coking reaction at 520°C and 1.0 MPa for 8 hours to obtain homogenized coke for fast charging energy storage.

[0098] Example 5

[0099] Preparation of homogenized coke for fast charging energy storage

[0100] (1) Carbon nanotubes, polyvinyl alcohol (dispersant), and cetyltrimethylammonium bromide (surfactant) were mixed with ethylene tar (dispersion solvent), high-pressure homogenized for 1.5 hours, and then ultrasonically treated to obtain a homogenized slurry;

[0101] The addition amounts of carbon nanotubes, polyvinyl alcohol, and cetyltrimethylammonium bromide were 2 ‰, 0.9%, and 0.4 ‰ of the mass of the homogenized slurry, respectively;

[0102] (2) The homogenized slurry was mixed with vacuum residue pretreated by filtration settlement, catalytic hydrogenation, and vacuum distillation at high speed to obtain a reaction raw material;

[0103] The addition amount of the homogenized slurry was 50% of the mass of the reaction raw material;

[0104] Among them, the specific reaction conditions of filtration settlement, catalytic hydrogenation, and vacuum distillation were the same as in Example Two:

[0105] (3) The reaction raw material was subjected to coking reaction at 450°C and 0.4 MPa for 24 hours to obtain homogenized coke for fast charging energy storage.

[0106] Example 6

[0107] Preparation of homogenized coke for fast charging energy storage

[0108] (1) Carbon nanotubes, polyvinylpyrrolidone (dispersant), sodium dodecyl sulfate (surfactant) and coking wax oil (dispersion solvent) were mixed, and after 1 hour of dispersion by high-pressure homogenizer, ultrasonic treatment was performed to obtain a homogeneous slurry;

[0109] The addition amounts of carbon nanotubes, polyvinylpyrrolidone, sodium dodecyl sulfate and coking wax oil were 0.5‰, 0.5% and 0.1‰ of the mass of the homogeneous slurry, respectively;

[0110] (2) The homogeneous slurry was mixed with the catalytic cracking slurry oil pretreated by filtration settlement, catalytic hydrogenation and vacuum distillation by high-speed stirring to obtain a reaction raw material;

[0111] The addition amount of the homogeneous slurry was 5% of the mass of the reaction raw material;

[0112] The specific reaction conditions of filtration settlement, catalytic hydrogenation and vacuum distillation were the same as in Example 1:

[0113] (3) The reaction raw material was subjected to coking reaction at 480℃ and 0.8MPa for 24 hours to obtain a homogeneous coke for fast charging energy storage.

[0114] Comparative Example 1

[0115] The difference between this comparative example and Example 1 is that no carbon nanotubes are introduced into the raw material system;

[0116] The specific preparation steps are as follows:

[0117] The catalytic cracking slurry oil pretreated by filtration settlement, catalytic hydrogenation and vacuum distillation was reacted at 480℃ and 0.6MPa for 12 hours to obtain acicular coke.

[0118] Comparative Example 2

[0119] The difference between this comparative example and Example 1 is that no surfactant is introduced into the raw material system;

[0120] The specific preparation steps are as follows:

[0121] (1) Carbon nanotubes, polyvinylpyrrolidone (dispersant) and coking wax oil (dispersion solvent) were mixed, and after 3 hours of ball milling, ultrasonic treatment was performed to obtain a homogeneous slurry;

[0122] The addition amounts of carbon nanotubes, sodium dodecyl sulfate and coking wax oil were 1.5‰ and 0.3‰ of the mass of the homogeneous slurry, respectively;

[0123] (2) The homogeneous slurry was mixed with the catalytic cracking slurry oil pretreated by filtration settlement, catalytic hydrogenation and vacuum distillation by high-speed stirring to obtain a reaction raw material;

[0124] The addition amount of the homogeneous slurry is 20% of the mass of the reaction raw material.

[0125] The specific reaction conditions of the filtration sedimentation, catalytic hydrogenation and vacuum fractionation are the same as those in Example One.

[0126] The reaction raw material is subjected to coking at 480℃ and 0.6MPa for 12 hours to obtain the homogeneous coke for fast charging and energy storage.

[0127] Comparative Example 3

[0128] The difference between this comparative example and Example 1 is that:

[0129] The coking temperature is 430℃, and the rest is the same as Example 1.

[0130] Comparative Example 4

[0131] The difference between this comparative example and Example 1 is that:

[0132] The main oil slurry uses the catalytic cracking slurry without pretreatment, with ash content of 0.3% and sulfur content of 0.8%;

[0133] The rest is the same as Example 1.

[0134] Comparative Example 5

[0135] The difference between this comparative example and Example 1 is that:

[0136] The dispersant is starch, and the rest is the same as Example 1.

[0137] Comparative Example 6

[0138] The difference between this comparative example and Example 1 is that:

[0139] The carbon nanotube, polyvinylpyrrolidone (dispersant) and sodium dodecyl sulfate (surfactant) are directly mixed with the pretreated oil slurry, and the rest is the same as Example 1.

[0140] Comparative Example 7

[0141] The difference between this comparative example and Example 1 is that:

[0142] The pretreated oil slurry is coal tar mentioned in patent CN1306070A, and the rest is the same as Example 1.

[0143] Test Example

[0144] The graphitized homogeneous coke obtained in Examples 1-6 and Comparative Examples 1-7 is used as the negative electrode material to prepare a battery.

[0145] The reaction parameters for graphitization are to control the graphitization temperature to be 2800℃.

[0146] The negative material, conductive carbon black (Super P, conductive agent), carboxymethyl cellulose (CMC, thickening agent), and butadiene rubber (SBR, binder) are mixed in a ratio of 94:2:2:2 to form a slurry, which is uniformly coated on a copper foil current collector, dried to obtain a negative electrode sheet, and assembled into a button cell in a glove box. The selected counter electrode is a lithium metal sheet, the separator is a polypropylene microporous membrane, and the electrolyte is 1M lithium hexafluorophosphate (the solvent is a mixture of ethylene carbonate, dimethyl carbonate, and diethyl carbonate).

[0147] The assembled button cell is subjected to constant current charge and discharge test, the test current is 1C, and the test voltage window is 0.005-2V. The test results are shown in Table 1.

[0148] SOP test:

[0149] First, the sample is prepared. The homogeneous coke particles are crushed and ground to 0.2-1mm, mixed with a curing agent, and polished to form a smooth plane sample. Then, the prepared sample is placed under a polarizing microscope for observation. Adjust the microscope to the orthogonal polarized state, and use an objective lens with a magnification of 50 times. Under the microscope, bright and vivid interference colors (such as blue, yellow or red) will be displayed, and the microstructure such as "flaky" or "fibrous" can be clearly seen. According to the size, shape, and convexity of the isochromatic zone, the sample is identified. The volume percentage of each optical structure is randomly calculated by the dot method. The specific identification criteria are shown in Table 1.

[0150] Table 1 Optical structure identification criteria

[0151]

[0152] Test results:

[0153] Table 2 Battery performance

[0154]

[0155] In the fast-charging energy storage homogeneous coke prepared in Example 1, the proportion of small polarized structures is 65%, and the structure is as shown in Figure 1As shown, the S content is 0.3%, the ash content is 0.12%, and the volatile content is 7.5%. After the negative electrode is prepared, the capacity retention rate is > 95% after 500 cycles at 6C rate. Comparative Example 1 does not add carbon nanotubes, the small piece structure accounts for only 45%, the mosaic structure accounts for 25%, the sulfur content is 0.4%, and the ash content is 0.15%. The capacity attenuation is > 10% after 500 cycles at 6C. Comparative Example 2 does not introduce a surfactant during the dispersion process, the carbon nanotubes are not uniformly dispersed, the small piece structure accounts for 50%, and the mosaic structure accounts for 20%. The capacity attenuation is > 5% after 500 cycles at 6C. In Comparative Example 3, the coking is not complete, the volatile content is as high as 12%, the small piece structure accounts for 40%, and the mosaic structure accounts for 30%. The 1C reversible capacity is only 352 mAh / g. In Comparative Example 4, the main oil slurry is not pretreated, the ash content and sulfur content are excessive, the small piece structure accounts for 55%, and the mosaic structure accounts for 15%. The battery cycle stability is poor, and the capacity attenuation is > 10% after 200 cycles at 6C. In Comparative Example 5, a non-recommended dispersant is used, the carbon nanotubes are not uniformly dispersed, the small piece structure accounts for 48%, and the mosaic structure accounts for 22%. The capacity attenuation is > 10% after 500 cycles at 6C. In Comparative Example 6, the CNT is directly dispersed in the pretreated oil slurry, the dispersion uniformity is poor, the small piece accounts for 52%, and the capacity retention rate is only 90% after 500 cycles at 6C. In Comparative Example 7, coal tar is used as the main oil slurry, the graphitization capacity is low, and the 1C initial discharge specific capacity is only 346 mAh / g.

[0156] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A fast charging energy storage homogenized coke, characterized by, The fast-charging energy storage homogeneous coke has a polarized structure small piece ratio of greater than or equal to 60%, an inlaid structure of less than or equal to 10%, sulfur content of less than or equal to 0.5%, ash content of less than or equal to 0.15%, and volatile content of less than or equal to 8.0%; The polarized structure small piece has a size of 10-30 μm in length and 10-30 μm in width. The inlaid structure has a size of less than 10 μm in length and less than 10 μm in width. The preparation method of the fast-charging energy storage homogeneous coke comprises the following steps: S1: mixing carbon nanotubes, a dispersant, a surfactant, and a dispersion solvent to obtain a homogeneous slurry; S2: mixing the homogeneous slurry and pretreated oil slurry to obtain reaction raw materials, and performing coking reaction on the reaction raw materials to generate fast-charging energy storage homogeneous coke; In step S1, the dispersion solvent is one or more of coking diesel oil, coking wax oil, and ethylene tar; The dispersant is one or more of polyvinylpyrrolidone, polyethylene glycol, polystyrene sulfonic acid sodium, polyacrylic acid, polyvinyl alcohol, or polyaniline; In step S2, the oil slurry is one or more of catalytic cracking oil slurry, vacuum residue, and backfrying oil; The pretreatment process is filtration sedimentation, catalytic hydrogenation, and vacuum fractionation, the filtration sedimentation controls the oil slurry ash content to be less than or equal to 0.15%, the catalytic hydrogenation controls the oil slurry sulfur content to be less than or equal to 0.5%, and the vacuum fractionation controls the oil slurry initial boiling point to be greater than or equal to 250 ℃.

2. The fast charging energy storage homogenizing coke according to claim 1, characterized in that, In step S2, the coking reaction has a reaction temperature of 450-520 ℃, a reaction pressure of 0.4-1.0 MPa, and a reaction time of 8-24 h.

3. The fast charging energy storage homogenizing coke according to claim 1, characterized in that, In step S1, the carbon nanotubes, the dispersant, and the surfactant are added in amounts of 0.5‰-5%, 0.5-1%, and 0.1‰-0.5‰, respectively, based on the mass of the homogeneous slurry; In step S2, the homogeneous slurry is added in an amount of 5%-50% based on the mass of the reaction raw materials.

4. The fast charging energy storage homogenizing coke according to claim 1, characterized in that, In step S1, the surfactant is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium cholate, sodium deoxycholate, or cetyltrimethylammonium bromide.

5. The use of the fast-charging energy storage homogenized coke according to claim 1 in the preparation of a negative material for lithium-ion batteries, characterized in that, The lithium ion battery is a fast-charging lithium ion battery.

6. A lithium-ion battery anode material, characterized in that, The fast-charging energy storage homogeneous coke of claim 1.

7. A lithium ion battery comprising a positive electrode, a negative electrode and an electrolyte, characterized in that, The negative electrode comprises the lithium ion battery negative electrode material of claim 6, and the lithium ion battery has an energy density of greater than or equal to 180 Wh / kg at a 3C rate and a capacity attenuation of less than 10% after 500 cycles at a 6C rate.

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