A negative electrode material for a sodium-ion battery, a preparation method thereof, a negative electrode sheet, and a sodium-ion battery

Abstract

The present disclosure relates to a negative electrode material for a sodium-ion battery, a preparation method thereof, a negative electrode sheet and a sodium-ion battery. The preparation method comprises the following steps: S1, performing first ball milling treatment on gasification slag to obtain a first product, the gasification slag comprising slag generated in a heavy oil gasification process; S2, performing surface acid removal treatment on the first product to obtain a second product; S3, performing second wet ball milling treatment and spray drying treatment on the second product to obtain a third product; and S4, performing calcination treatment on the third product. The present disclosure uses gasification slag as a raw material to prepare a negative electrode material for a sodium-ion battery, which not only has low cost, but also enables high value-added utilization of the slag, and has a wide application prospect.

Description

Technical Field

[0001] The present disclosure relates to the technical field of sodium ion batteries, and in particular to a negative electrode material for a sodium ion battery, a preparation method thereof, a negative electrode sheet, and a sodium ion battery. Background Art

[0002] Sodium, due to its abundant reserves, widespread distribution, and low price, has made sodium-ion batteries a hot topic in electrochemical energy storage research. Currently, sodium-ion batteries are being used in low-speed electric vehicles and large-scale energy storage, and the market is gradually expanding. It is foreseeable that sodium-ion batteries will become an important complement to lithium-ion battery technology, with the two developing in tandem and having complementary applications.

[0003] There are many types of anode materials for sodium-ion batteries, among which carbon-based materials are currently the best due to their high performance and wide availability. Hard carbon, with its excellent sodium storage capacity, is considered the most ideal carbon-based sodium storage material. However, the disadvantages of hard carbon anodes include low initial coulombic efficiency, high carbonization cost, and insufficient cycle and rate performance. Unlike hard carbon, soft carbon, while having a low specific capacity, has a high initial coulombic efficiency, low manufacturing cost, and easy process control, making it a promising anode material for sodium-ion batteries.

[0004] CN115084436A discloses a preparation method and application of a pitch-based soft carbon negative electrode material for sodium ion batteries. Under inert gas, pitches with different softening points are matched and calcined at low temperature to obtain soft carbon. CN111293309A discloses a performance improvement method and application of a coal-based sodium ion battery negative electrode material. The coal-based material is mixed with a soft carbon precursor, and after low-temperature treatment, it is placed in a high-temperature carbonization furnace for carbonization to obtain an amorphous carbon material, which is the coal-based sodium ion battery negative electrode material. CN113526489A discloses a performance improvement method and application of a carbon-based negative electrode material for sodium ion batteries. The soft carbon precursor is pre-oxidized and then mixed with a hard carbon precursor to form a mixed material, which is placed in a high-temperature carbonization furnace to obtain an amorphous carbon material, which is the carbon-based negative electrode material for sodium ion batteries. CN114516627A discloses a method for preparing a soft and hard carbon composite nanomaterial, which uses purified weathered coal humic acid as a hard carbon source and asphalt as a soft carbon source, combined with a pore-adjusting agent, to prepare a soft and hard carbon composite sodium ion battery negative electrode material through a two-step high-temperature reaction.

[0005] The soft carbons mentioned in the above literature are all one or more of asphalt, petroleum coke, and needle coke, which are end products of petroleum refining. When used as raw materials for sodium-ion battery anodes, they require a certain cost. In order to increase the "hardness" of soft carbon materials, a strategy of carbonizing soft and hard carbon precursors together can be adopted to prepare sodium-ion battery anode materials, but this undoubtedly increases costs. In summary, the development of low-cost, easy-to-use sodium-ion battery anode materials is of great significance to promoting the industrialization of sodium-ion batteries. Summary of the Invention

[0006] The present invention aims to provide a negative electrode material for a sodium ion battery, a preparation method thereof, a negative electrode plate, and a sodium ion battery. The negative electrode material for a sodium ion battery is prepared by using gasified ash as a raw material, which not only has low cost but also enables the ash to be utilized with high added value, and has broad application prospects.

[0007] In order to achieve the above objectives, the present disclosure provides a first aspect of a method for preparing a negative electrode material for a sodium ion battery, comprising the following steps:

[0008] S1. performing a first ball milling process on gasified ash to obtain a first product, wherein the gasified ash includes ash generated during heavy oil gasification;

[0009] S2, performing a surface deacidification treatment on the first product to obtain a second product;

[0010] S3, subjecting the second product to a second wet ball milling process and a spray drying process to obtain a third product;

[0011] S4, calcining the third product.

[0012] Optionally, the gasified ash is prepared by removing metal from the ash raw material;

[0013] Preferably, the metal removal process is a hydrometallurgical metal recovery process; optionally, the conditions of the hydrometallurgical metal recovery process include:

[0014] The ash raw material is dried and dehydrated, and then crushed to a particle size within the range of 10 to 100 μm to obtain a crushed ash raw material; the crushed ash raw material is mixed with an acid solution, and then acid hydrolyzed under stirring and reflux; the product obtained by the acid hydrolysis is filtered to obtain a gasified ash with metal removed;

[0015] Optionally, the acid solution is selected from one or more of hydrochloric acid, sulfuric acid and nitric acid, preferably sulfuric acid and / or hydrochloric acid; the mixing weight ratio of the acid solution to the crushed ash raw material is 1 to 20:1, preferably 2 to 10:1; optionally, the stirring reflux temperature is room temperature or 45 to 100° C., and the acid hydrolysis treatment time is 3 to 6 hours;

[0016] Optionally, the ash raw material is selected from one or more of vacuum residue gasification ash, residue hydrocracking tail oil gasification ash, deoiled asphalt gasification ash, catalytic oil slurry ash and ethylene tar ash;

[0017] Optionally, based on the total weight of the ash raw material, the C content in the ash raw material is 82-92 weight%, the H content is 1-10 weight%, the S content is 0.1-5 weight%, the N content is 0.1-5 weight%, the O content is 0.1-5 weight%, and the total content of impurity metals is 0.1-5 weight%, and the impurity metals include Ni, Mo, V, Fe, Na and Ga;

[0018] Preferably, based on the total weight of the gasified ash obtained after the metal removal treatment, the C content in the gasified ash obtained after the metal removal treatment is 84-92 weight%, the H content is 1-6 weight%, the S content is 0.1-5 weight%, the N content is 0.1-3 weight%, the O content is 0.1-5 weight%, and the total content of impurity metals is 0.1-3 weight%.

[0019] Optionally, the conditions of the first ball milling treatment include dry ball milling treatment and / or first wet ball milling treatment; preferably, the first wet ball milling treatment;

[0020] Optionally, the conditions of the first wet ball milling treatment include: a ball milling speed of 200 to 1000 rpm, preferably 300 to 800 rpm; a ball milling time of 0.5 to 12 hours, preferably 2 to 6 hours; a ball milling temperature of 10 to 50° C., preferably 20 to 40° C.; a ball-to-material ratio of 1 to 40, preferably 10 to 30; an amount of the first ball milling solvent per 1 g of the gasified ash, preferably 20 to 100 mL; optionally, the first ball milling solvent is selected from one or more of ethanol, nitrogen methyl pyrrolidone, cyclohexane, sulfolane, and tetrahydrofuran;

[0021] Preferably, the method further comprises: drying the product obtained by wet ball milling by rotary evaporation; preferably, the rotary evaporation conditions include: a temperature of 40 to 200° C., preferably 40 to 120° C.;

[0022] Optionally, the conditions for the dry ball milling treatment include: a ball milling speed of 200-450 rpm, preferably 250-350 rpm; a ball milling time of 1-8 h, preferably 2-6 h; a ball milling temperature of 10-50° C., preferably 20-40° C.; and a ball-to-material ratio of 1-40, preferably 10-30.

[0023] Optionally, in step S2, the surface deacidification treatment is a water washing treatment or an alkali washing treatment; the water washing treatment and the alkali washing treatment are independently carried out by stirring cleaning or ultrasonic cleaning;

[0024] Optionally, the conditions for the water washing treatment include: contacting the first product with deionized water, then stirring and filtering to obtain a filter residue; repeating this process more than three times to obtain a second product; optionally, the weight ratio of deionized water to the first product is 1 to 50:1, preferably 10 to 20:1; the conditions for the stirring treatment include: a stirring speed of 100 to 1000 rpm, a stirring time of 2 to 12 hours, preferably, a stirring speed of 200 to 400 rpm, and a stirring time of 4 to 8 hours;

[0025] Optionally, the conditions for the alkali washing treatment include: an alkali solution concentration of 0.1 to 10 mol / L, preferably 0.1 to 5 mol / L; preferably, the alkali solution is selected from an aqueous alkali solution; the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium bicarbonate and sodium carbonate; and the amount of the alkali solution used relative to 1 g of the first product is 1 to 100 mL, preferably 10 to 50 mL;

[0026] Optionally, when stirring cleaning is adopted, the stirring temperature is 20-60°C, the stirring speed is 200-600 rpm, and the stirring time is 1-12 hours; preferably, the stirring temperature is 20-40°C, the stirring speed is 200-450 rpm, and the stirring time is 2-8 hours;

[0027] Optionally, when ultrasonic cleaning is adopted, the ultrasound is carried out in a closed constant temperature environment, the ultrasound time is 3 to 8 hours, the ultrasound power is 600 to 3000W, and the ultrasound frequency is 20 to 80KHz; preferably, the ultrasound time is 3 to 7 hours, the ultrasound power is 400 to 1000W, and the ultrasound frequency is 40 to 60KHz.

[0028] Optionally, in step S3, the conditions for the second wet ball milling treatment include:

[0029] The ball milling speed is 200-1000 rpm, preferably 600-900 rpm; the ball milling time is 1-12 h, preferably 6-12 h; the ball milling temperature is 10-50° C., preferably 20-40° C.; the ball-to-material ratio is 1-40, preferably 15-30; the amount of the second ball milling solvent used is 10-100 mL, preferably 20-100 mL, relative to 1 g of the second product; optionally, the second ball milling solvent is selected from one or more of ethanol, nitrogen methyl pyrrolidone, cyclohexane, sulfolane, and tetrahydrofuran;

[0030] Preferably, in step S3, the conditions of the spray drying treatment include: a feed temperature of 120 to 200° C., an outlet temperature of 80 to 100° C., a carrier gas flow rate of 12 to 20 L / min, an inlet pressure of 0.3 to 0.8 MPa, and the carrier gas is selected from one or more of nitrogen and argon;

[0031] Preferably, the feed temperature is 140-190° C., the outlet temperature is 90-100° C., the carrier gas flow rate is 14-18 L / min, and the inlet pressure is 0.4-0.6 MPa.

[0032] Optionally, during the second wet ball milling process, a coating modifier is further added to coat and modify the gasification ash;

[0033] Preferably, the coating modifier is selected from one or more of phenolic resin, epoxy resin, polyfurfuryl alcohol resin and polyethylene;

[0034] Preferably, the weight ratio of the coating modifier to the second product is 0.02 to 0.2:1, preferably 0.05 to 0.15:1.

[0035] Optionally, in step S4, the calcination treatment conditions include: heating to 600-1500° C., preferably 750-1300° C., in an inert gas atmosphere, and holding for 1-6 hours, preferably 2-4 hours; optionally, heating at a rate of 0.5-5° C. / min, preferably 1-3° C. / min; or,

[0036] The calcination treatment conditions include: in an inert gas atmosphere, first heating to 700-1000°C at a first heating rate, holding for 1-6 hours, then heating to 1000-1700°C at a second heating rate, holding for 1-6 hours; preferably, first heating to 800-1000°C at the first heating rate, holding for 2-4 hours, then heating to 1000-1300°C at the second heating rate, holding for 2-4 hours; further preferably, the first heating rate is 1-10°C / min, preferably 1-5°C / min, and the second heating rate is 1-7°C / min, preferably 1-3°C / min;

[0037] Optionally, the inert gas is selected from one or more of nitrogen, helium, and argon; the water content of the inert gas is less than 0.1 wt%, and the oxygen content is less than 0.1 wt%.

[0038] A second aspect of the present disclosure provides a negative electrode material for a sodium ion battery prepared according to the method described in the first aspect of the present disclosure.

[0039] Optionally, based on the total weight of the negative electrode material, the carbon content is greater than 90 weight %, the hydrogen content is less than 3 weight %, and the content of other impurity elements is less than 7 weight %, wherein the other impurity elements include one or more of sulfur, nitrogen, oxygen, and impurity metals, and the impurity metals include Ni, Mo, V, Fe, Na, and Ga;

[0040] Optionally, the D of the negative electrode material 50 Particle size is 1~50μm, BET specific surface area is 1~500m 2 / g; preferably, the average particle size of the negative electrode material is 5 to 12 μm, and the BET specific surface area is 1 to 200 m 2 / g.

[0041] A third aspect of the present disclosure provides a negative electrode plate for a sodium ion battery, comprising the negative electrode material described in the second aspect of the present disclosure.

[0042] Optionally, the negative electrode sheet is prepared by a method comprising the following steps: preparing the negative electrode material into a negative electrode slurry, coating the slurry on the surface of a negative electrode current collector, and drying the slurry;

[0043] Preferably, the negative electrode slurry comprises the negative electrode material, a conductive material, a dispersant and a binder;

[0044] Preferably, the weight ratio of the negative electrode material: conductive material: dispersant: binder is 60-96:0.01-5:1-10:1-10, preferably 80-96:0.02-10:1-5:1-5;

[0045] Optionally, the conductive agent material is selected from one or more of highly conductive carbon black, conductive graphite, acetylene black, Ketjen black, single-walled carbon nanotubes, multi-walled carbon nanotubes and carbon nanofibers;

[0046] Optionally, the dispersant is selected from one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium alginate, polyvinyl alcohol, chitosan and β-cyclodextrin;

[0047] Optionally, the binder is selected from one or more of styrene-butadiene copolymer, polyacrylic acid, sodium polyacrylate, polyimide, polyvinylidene fluoride, nitrile rubber, butadiene rubber, xanthan gum and gum arabic.

[0048] A fourth aspect of the present disclosure provides a sodium ion battery, which includes a positive electrode plate, the negative electrode plate described in the third aspect of the present disclosure, a battery separator and an electrolyte.

[0049] Optionally, the electrolyte is selected from one or more of an ester electrolyte, an ether electrolyte and a sulfone electrolyte;

[0050] Optionally, the ester electrolyte is selected from one or more of ethylene carbonate, vinylene carbonate, vinyl ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate and fluorocarbonate;

[0051] Optionally, the ether electrolyte is selected from one or more of 1,3-dioxolane, 1,4-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, perfluorohexane, 1,2-bis(cyanoethoxy)ethane and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether;

[0052] Optionally, the sulfone electrolyte is selected from one or more of dimethyl sulfoxide, tetramethylene sulfone, ethyl methyl sulfone, tetramethyl sulfone, sulfolane and methoxyethyl methyl sulfone.

[0053] Through the above technical solution, the present disclosure provides a negative electrode material for sodium ion batteries and its preparation method, a negative electrode plate and a sodium ion battery. The negative electrode material of the sodium ion battery has low cost, easy raw materials, high first coulombic efficiency, good cycle performance and good safety performance. In addition, the negative electrode material is derived from gasification ash, which can expand the high value-added utilization of gasification ash. Compared with the direct incineration of gasification ash, the utilization process is more environmentally friendly. The sodium ion battery using the negative electrode material provided by the present disclosure can meet a variety of application scenarios such as low-speed electric vehicles, home backup power supplies, smart grid peak-shaving energy storage equipment, distributed energy storage, communication base stations, etc.

[0054] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0056] Figure 1 This is a scanning electron microscope (SEM) image of the negative electrode material obtained in Example 1 of the present disclosure;

[0057] Figure 2 This is a comparison chart of the first coulombic efficiency of the batteries in Test Example 1 (using the negative electrode material obtained in Example 1) and Test Example 2 of the present disclosure;

[0058] Figure 3 This is a comparison chart of the first coulombic efficiency of the batteries in Test Example 1 (using the negative electrode material obtained in Example 4) and Test Example 3 (using the negative electrode material obtained in Example 4) of the present disclosure;

[0059] Figure 4 1 is a comparison chart of the cycle performance of batteries at different rates in Test Example 1 (using the negative electrode material obtained in Example 1) and Test Example 2 (using the negative electrode material obtained in Example 1);

[0060] Figure 5 1 is a comparison chart of the cycle performance at different rates of the batteries in Test Example 1 (using the negative electrode material obtained in Example 4) and Test Example 3 (using the negative electrode material obtained in Example 4);

[0061] Figure 6 1 is a comparison chart of the cycle performance at different rates of the batteries in Test Example 1 (using the negative electrode material obtained in Example 1) and Test Example 1 (using the negative electrode material obtained in Example 4) of the present disclosure. DETAILED DESCRIPTION

[0062] The following describes the specific embodiments of the present disclosure in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0063] According to the present disclosure, the current negative electrode materials in the field of sodium ion batteries are mainly carbon materials, including porous hard carbon and soft carbon. Hard carbon has a large interlayer spacing, a short-range ordered microstructure and a long-range disordered microstructure. It exhibits a high reversible capacity when used as the negative electrode of a sodium ion battery, but its disadvantages are low first coulombic efficiency, poor rate performance, and unsatisfactory cycle stability. Soft carbon has a high degree of order in its microstructure and is easy to form a graphite structure at high temperatures. When used as a negative electrode material for sodium ion batteries, it has good rate performance and cycle performance, and a high first coulombic efficiency. Its disadvantage is that its sodium storage capacity is relatively low. Therefore, the development of more low-cost soft carbon materials is critical to improving the competitiveness of soft carbon in the application of negative electrode materials for sodium ion batteries.

[0064] A first aspect of the present disclosure provides a method for preparing a negative electrode material for a sodium ion battery, comprising the following steps:

[0065] S1. performing a first ball milling process on gasified ash to obtain a first product, wherein the gasified ash includes ash generated during heavy oil gasification;

[0066] S2, performing a surface deacidification treatment on the first product to obtain a second product;

[0067] S3, subjecting the second product to a second wet ball milling process and a spray drying process to obtain a third product;

[0068] S4, calcining the third product.

[0069] The present disclosure provides a method for preparing a negative electrode material for a sodium-ion battery. This negative electrode material has low cost, readily available raw materials, high initial coulombic efficiency, and excellent cycle performance. It also possesses a high sodium storage capacity. Furthermore, this negative electrode material is derived from gasification ash, potentially expanding the high-value-added utilization of gasification ash. Compared to directly incinerating gasification ash, the utilization process is more environmentally friendly.

[0070] In a preferred embodiment, the gasified ash is prepared by removing metal from the ash raw material. Using the gasified ash after metal removal helps to avoid the influence of impurity metals on the performance of the conductive agent and reduce the performance of the negative electrode.

[0071] In one embodiment, the ash raw material is selected from one or more of vacuum residue gasification ash, residue hydrocracking tail oil gasification ash, deoiled asphalt gasification ash, catalytic oil slurry ash and ethylene tar ash; preferably, deoiled asphalt or catalytic oil slurry gasification ash is used as the raw material for preparing the negative electrode material;

[0072] Optionally, based on the total weight of the ash raw material, the C content in the ash raw material is 82-92 weight%, the H content is 1-10 weight%, the S content is 0.1-5 weight%, the N content is 0.1-5 weight%, the O content is 0.1-5 weight%, and the total content of impurity metals is 0.1-5 weight%, and the impurity metals include Ni, Mo, V, Fe, Na and Ga;

[0073] Preferably, based on the total weight of the gasified ash obtained after the metal removal treatment, the C content in the gasified ash obtained after the metal removal treatment is 84-92 weight%, the H content is 1-6 weight%, the S content is 0.1-5 weight%, the N content is 0.1-3 weight%, the O content is 0.1-5 weight%, and the total content of impurity metals is 0.1-3 weight%.

[0074] In a specific embodiment, the metal removal process is a hydrometallurgical metal recovery process; optionally, the conditions of the hydrometallurgical metal recovery process include:

[0075] The ash raw material is dried and dehydrated, and then crushed to a particle size within the range of 10 to 100 μm to obtain a crushed ash raw material; the crushed ash raw material is mixed with an acid solution, and then acid hydrolyzed under stirring and reflux; the product obtained by the acid hydrolysis is filtered to obtain a gasified ash with metal removed;

[0076] Optionally, the acid solution is selected from one or more of hydrochloric acid, sulfuric acid and nitric acid, preferably sulfuric acid and / or hydrochloric acid; the mixing weight ratio of the acid solution to the crushed ash raw material is 1 to 20:1, preferably 2 to 10:1; optionally, the stirring reflux temperature is room temperature or 45 to 100°C, and the acidolysis treatment time is 3 to 6 hours.

[0077] In one embodiment, the first ball milling treatment comprises dry ball milling and / or wet ball milling, preferably wet ball milling. In the present disclosure, during the ball milling treatment, the ball milling jar and the ball milling beads are made of zirconia.

[0078] In a specific embodiment, the conditions of the first wet ball milling treatment include: a ball milling speed of 200 to 1000 rpm, preferably 300 to 800 rpm; a ball milling time of 0.5 to 12 h, preferably 2 to 6 h; a ball milling temperature of 10 to 50° C., preferably 20 to 40° C.; a ball-to-material ratio of 1 to 40, preferably 10 to 30; relative to 1 g of the gasified ash, the amount of the first ball milling solvent is 10 to 200 mL, preferably 20 to 100 mL; optionally, the first ball milling solvent is selected from one or more of ethanol, nitrogen methyl pyrrolidone, cyclohexane, cyclopentane and tetrahydrofuran.

[0079] In a specific embodiment, the conditions for the dry ball milling treatment include: a ball milling speed of 200 to 450 rpm, preferably 250 to 350 rpm; a ball milling time of 1 to 8 hours, preferably 2 to 6 hours; a ball milling temperature of 10 to 50° C., preferably 20 to 40° C.; and a ball-to-material ratio of 1 to 40, preferably 10 to 30.

[0080] In the present disclosure, when the gasification ash is ball-milled by the first wet ball milling treatment to obtain the first ball-milling treatment product in the form of a suspension, the suspension needs to be treated to remove the liquid phase, for example, by rotary evaporation and drying to remove moisture. The rotary evaporation and drying temperature can be set to 40 to 200°C, preferably 40 to 120°C, and the rotary evaporation time can be 0.1 to 6 hours, preferably 0.5 to 2 hours.

[0081] In the present disclosure, by subjecting the gasification ash to a first ball milling treatment, the gasification ash can be broken into small particles, thereby increasing the conductive sites of the ash and exposing more acid sites to facilitate subsequent cleaning.

[0082] In one embodiment, in step S2, the surface deacidification treatment is water washing or alkali washing; the water washing and alkali washing are independently carried out by stirring cleaning or ultrasonic cleaning.

[0083] In a preferred embodiment, the conditions for the water washing treatment include: contacting the first product with deionized water, and then stirring and filtering to obtain a filter residue; repeating this process more than three times to obtain a second product; optionally, the weight ratio of deionized water to the first product is 1 to 50:1, preferably 10 to 20:1; the conditions for the stirring treatment include: a stirring speed of 100 to 1000 rpm, a stirring time of 2 to 12 hours, preferably, a stirring speed of 200 to 400 rpm, and a stirring time of 4 to 8 hours.

[0084] In a specific embodiment, the conditions for the alkali washing treatment include: an alkali solution concentration of 0.1 to 10 mol / L, preferably 0.1 to 5 mol / L; preferably, the alkali solution is selected from an aqueous alkali solution; the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium bicarbonate and sodium carbonate; relative to 1 g of the first product, the amount of the alkali solution is 1 to 100 mL, preferably 10 to 50 mL.

[0085] In a specific embodiment, when stirring cleaning is adopted during water washing or alkali washing, the stirring temperature is 20-60°C, the stirring speed is 200-600rpm, and the stirring time is 1-12h; preferably, the stirring temperature is 20-40°C, the stirring speed is 200-450rpm, and the stirring time is 2-6h; when ultrasonic cleaning is adopted during water washing or alkali washing, closed constant temperature ultrasound is used, the ultrasonic time is 3-8h, the ultrasonic power is 600-3000W, and the ultrasonic frequency is 20-80KHz; preferably, the ultrasonic time is 3-7h, the ultrasonic power is 400-1000W, and the ultrasonic frequency is 40-60KHz.

[0086] In a specific embodiment, the method further comprises: performing solid-liquid separation on the product obtained by the surface deacidification treatment to obtain a solid product; performing freeze-drying on the solid product to obtain the second product;

[0087] Optionally, the freeze-drying treatment conditions include: temperature of -80°C to -20°C, preferably -60°C to -30°C, time of 24 to 96 hours, preferably 48 to 72 hours, and vacuum degree of 0.1 to 100 Pa, preferably 1 to 10 Pa.

[0088] In one embodiment, in step S3, the conditions for the second wet ball milling treatment include: a ball milling speed of 200 to 1000 rpm, preferably 600 to 900 rpm; a ball milling time of 1 to 12 h, preferably 6 to 12 h; a ball milling temperature of 10 to 50° C., preferably 20 to 40° C.; a ball-to-material ratio of 1 to 40, preferably 15 to 30; and an amount of the second ball milling solvent relative to 1 g of the second product of 10 to 100 mL, preferably 20 to 100 mL; optionally, the second ball milling solvent is selected from one or more of ethanol, nitrogen methyl pyrrolidone, cyclohexane, sulfolane and tetrahydrofuran.

[0089] In one embodiment, in step S3, the spray drying conditions include: a feed temperature of 120 to 200° C., an outlet temperature of 80 to 100° C., a carrier gas flow rate of 12 to 20 L / min, an inlet pressure of 0.3 to 0.8 MPa, and the carrier gas is selected from one or more of nitrogen and argon;

[0090] Preferably, the feed temperature is 140-190° C., the outlet temperature is 90-100° C., the carrier gas flow rate is 14-18 L / min, and the inlet pressure is 0.4-0.6 MPa.

[0091] In one embodiment, during the second wet ball milling process, a coating modifier is further added to coat and modify the gasification ash;

[0092] Preferably, the coating modifier is selected from one or more of phenolic resin, epoxy resin, polyfurfuryl alcohol resin and polyethylene;

[0093] Preferably, the weight ratio of the coating modifier to the second product is 0.02 to 0.2:1, preferably 0.05 to 0.15:1. The present disclosure, by adding the coating modifier during the preparation process, can form a hard carbon coating on the surface of the resulting negative electrode material, which has the effect of reducing the specific surface area of ​​the gasified ash material and increasing the reversible insertion and extraction of sodium ions.

[0094] In one embodiment, in step S4, the calcination treatment conditions include: heating to 600-1500°C, preferably 750-1200°C, in an inert gas atmosphere, and holding time of 1-6 hours, preferably 2-4 hours; optionally, the heating rate is 0.5-5°C / min, preferably 1-3°C / min; or,

[0095] The conditions of the calcination treatment include: first heating to 700-1000℃ at a first heating rate, holding for 1-6h, then heating to 1000-1700℃ at a second heating rate, holding for 1-6h; preferably, first heating to 800-1000℃ at a first heating rate, holding for 2-4h, then heating to 1000-1300℃ at a second heating rate, holding for 2-4h; further preferably, the first heating rate is 1-10℃ / min, preferably 1-5℃ / min, and the second heating rate is 1-7℃ / min, preferably 1-3℃ / min.

[0096] Optionally, the inert gas is selected from one or more of nitrogen, helium, and argon; the inert atmosphere has a water content of 0.1wt% or less and an oxygen content of 0.1wt% or less.

[0097] The second aspect of the present disclosure provides a negative electrode material for sodium ion batteries prepared by the method according to the first aspect of the present disclosure.

[0098] In a preferred embodiment, the content of carbon is 90wt% or more, the content of hydrogen is 3wt% or less, and the content of other impurity elements is 7wt% or less, based on the total weight of the negative electrode material, the other impurity elements including one or more of sulfur, nitrogen, oxygen, and impurity metals, the impurity metals including Ni, Mo, V, Fe, Na, and Ga.

[0099] Optionally, the D50 of the negative electrode material is 1-50μm, the D90 of the negative electrode material is 5-100μm, and the D10 of the negative electrode material is 0.1-10μm. 50 The particle size is 1-50μm, the average pore size is 0.1-30nm, and the BET specific surface area is 1-500m 2 / g; preferably, the average particle size of the negative electrode material is 5-12μm, the average pore size is 0.5-15nm, and the BET specific surface area is 1-200m 2 / g.

[0100] The third aspect of the present disclosure provides a negative electrode sheet of a sodium ion battery, comprising the negative electrode material according to the second aspect of the present disclosure.

[0101] In a specific embodiment, the negative electrode sheet is prepared by a method comprising the following steps: preparing a negative electrode slurry from the negative electrode material, then coating the negative electrode slurry on the surface of a negative electrode current collector, and drying to obtain the negative electrode sheet.

[0102] In a preferred embodiment, the negative electrode slurry comprises the negative electrode material, a conductive agent material, a dispersant, and a binder.

[0103] Preferably, the weight ratio of the negative electrode material: conductive material: dispersant: binder is 60-96:0.01-5:1-10:1-10, preferably 80-96:0.02-10:1-5:1-5.

[0104] In one embodiment, the conductive agent is selected from one or more of highly conductive carbon black, conductive graphite, acetylene black, Ketjen black, single-walled carbon nanotubes, multi-walled carbon nanotubes and carbon nanofibers;

[0105] The dispersant is selected from one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium alginate, polyvinyl alcohol, chitosan and β-cyclodextrin;

[0106] The binder is selected from one or more of styrene-butadiene copolymer, polyacrylic acid, sodium polyacrylate, polyimide, polyvinylidene fluoride, nitrile rubber, butadiene rubber, xanthan gum and gum arabic.

[0107] The conductive material, dispersant and binder in the negative electrode slurry disclosed herein can be purchased through common commercial channels or prepared by known methods.

[0108] A fourth aspect of the present disclosure provides a sodium ion battery, which includes a positive electrode plate, the negative electrode plate described in the third aspect of the present disclosure, a battery separator, and an electrolyte.

[0109] The sodium ion battery using the negative electrode material provided by the present disclosure can meet various application scenarios such as low-speed electric vehicles, home backup power supplies, smart grid peak-shaving energy storage equipment, distributed energy storage, communication base stations, etc.

[0110] In the present disclosure, the positive electrode, electrolyte, and separator used in the sodium ion battery can be various materials conventionally adapted in the art, and the present disclosure does not specifically limit this. For example, the separator can be selected from any one of a polyethylene film, a polypropylene film, an inorganic oxide-modified polymer multilayer film, and a cellulose film, and the positive electrode can be selected from one or more of a metal oxide layered structure, a polyanion structure, and a Prussian blue structure. The composition of the sodium ion battery provided in the present disclosure is a conventional composition in the art.

[0111] In one embodiment, the electrolyte is selected from one or more of an ester electrolyte, an ether electrolyte, and a sulfone electrolyte;

[0112] Optionally, the ester electrolyte is selected from one or more of ethylene carbonate, vinylene carbonate, vinyl ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate and fluorocarbonate;

[0113] Optionally, the ether electrolyte is selected from one or more of 1,3-dioxolane, 1,4-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, perfluorohexane, 1,2-bis(cyanoethoxy)ethane and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0114] Optionally, the sulfone electrolyte is selected from one or more of dimethyl sulfoxide, tetramethylene sulfone, sulfolane, ethyl methyl sulfone, tetramethyl sulfone and methoxyethyl methyl sulfone.

[0115] In a preferred embodiment, the electrolyte is an ether electrolyte.

[0116] The present disclosure is further described in detail below through examples. The raw materials used in the examples can be obtained through commercial channels.

[0117] The particle size was measured using an optical particle size analyzer, using the Mastersizer 3000 as the instrument model;

[0118] The nitrogen adsorption-desorption curve, average pore size, BET specific surface area and total pore volume were measured using the JW-BK200 series static capacity method.

[0119] The SEM test method is scanning electron microscopy, and the instrument model is S4800 from Hitachi, Japan;

[0120] The electrochemical cycling performance was tested using the Blue Electric test system, with the instrument model being CT3001A.

[0121] Example 1

[0122] (1) The deoiled asphalt ash raw material used in this embodiment (based on the total weight of the asphalt ash raw material, the C content in the ash raw material is 86% by weight, the H content is 4% by weight, the S content is 2% by weight, the N content is 1% by weight, the O content is 5% by weight, and the total content of impurity metals is 2% by weight), and the ash raw material is subjected to a hydrometallurgical metal recovery process, specifically comprising: drying and dehydrating the asphalt ash raw material and then crushing it to a particle size of 10 to 100 μm; mixing the gasified ash with 1.5 mol / L sulfuric acid at a mass ratio of 10:1, stirring at room temperature, and performing acid hydrolysis for 6 hours. After acid hydrolysis, filtering can obtain the gasified ash after metal removal. Based on the total weight of the gasified ash obtained after metal removal treatment, the C content in the gasified ash obtained after metal removal treatment is 88% by weight, the H content is 4% by weight, the S content is 2.1% by weight, the N content is 1.1% by weight, the O content is 4.5% by weight, and the total content of impurity metals is 0.3% by weight.

[0123] (2) 5 g of the asphalt gasification ash after metal removal was dispersed in 100 mL of ethanol and mixed evenly. The amount of the first ball milling solvent used was 20 mL relative to 1 g of the gasification ash.

[0124] (3) The mixture was placed in a 500 mL zirconia ball mill, and 75 g of 1 mm zirconia beads were added, with a ball-to-material ratio of 20. The mixture was then placed in a planetary ball mill for the first wet milling process, with the mill speed set at 450 rpm, the milling time set at 6 h, and the temperature set at 30°C.

[0125] (4) The suspension after ball milling is subjected to rotary evaporation and drying at a temperature set to 60° C. to obtain the first product.

[0126] (5) The dried powder (first product) was collected and placed in a 300 ml beaker. 100 ml of a 0.5 mol / L potassium hydroxide solution was added and mixed evenly. The mixture was then washed with alkali, wherein the amount of alkali solution used was 20 ml per 1 g of the first product.

[0127] (6) The mixed liquid was then stirred using a magnetic stirrer at room temperature (25°C), a rotation speed of 400 rpm, and a stirring time of 8 h.

[0128] (7) After alkali washing, the mixture was filtered and then dried by freeze drying with the temperature set at -60°C, the drying time set at 48h, and the vacuum degree set at 8Pa.

[0129] (8) The freeze-dried powder (second product) was subjected to a second wet ball milling process at a speed of 600 rpm, a time of 6 h, and a temperature of 30°C. The solvent was 100 mL of ethanol. The amount of solvent used in the second ball milling was 20 mL per 1 g of the second product. The amount of 1 mm zirconia beads was 75 g, and the ball-to-material ratio was 20.

[0130] (9) After the second wet ball milling treatment is completed, the suspension liquid is spray dried. The spray drying conditions are: inlet temperature of 170°C, outlet temperature of 90°C, feed rate of 10 ml / min, carrier gas flow rate of 15 L / min, inlet pressure of 0.5 MPa, and carrier gas is nitrogen gas to obtain the third product.

[0131] (10) The dried powder (the third product) was placed in an atmosphere furnace for calcination and carbonization. The calcination conditions were as follows: in an Ar atmosphere, the temperature was raised to 800°C at 3°C / min, then kept at this temperature for 2 h, and then raised to 1200°C at 2°C / min, and kept at this temperature for 2 h. Finally, the negative electrode material was obtained.

[0132] Figure 1The following is a scanning electron microscope (SEM) image of the negative electrode material prepared in this example. Figure 1 It can be seen that the negative electrode material has a spherical or quasi-spherical structure, and there are pore structures of different sizes on the surface.

[0133] Example 2

[0134] This embodiment refers to the preparation method in Example 1, and differs from Example 1 in that: no ethanol is added in step (2), and the first ball milling treatment in step (3) is directly performed, that is, dry ball milling treatment is adopted. The rest of the process is the same as in Example 1, and finally the negative electrode material is obtained.

[0135] Example 3

[0136] This embodiment refers to the preparation method in Example 1, and the difference from Example 1 is that the rotation speed of the second wet ball milling treatment in step (7) is adjusted to 800 rpm, and the rest of the process is the same as Example 1, and finally the negative electrode material is obtained.

[0137] Example 4

[0138] This example refers to the preparation method in Example 1, and differs from Example 1 in that: during the second wet ball milling treatment in step (7), 0.75 g of phenolic resin is added at the same time as 100 mL of ethanol, and the weight ratio of phenolic resin to the second product is 0.15:1. The remaining process is the same as in Example 1, and finally a negative electrode material is obtained.

[0139] Example 5

[0140] This embodiment refers to the preparation method in Example 1. The difference between this embodiment and Example 1 is that a one-step calcination method is used in step (9), specifically comprising:

[0141] In an Ar atmosphere, the temperature was raised to 1200° C. at a rate of 3° C. / min and then kept at this temperature for 4 h. The remaining process was the same as in Example 1, and finally the negative electrode material was obtained.

[0142] Example 6

[0143] This embodiment refers to the preparation method of Example 1, but differs from Example 1 in that the type of ash raw material and the conditions for metal removal treatment are changed.

[0144] This embodiment uses vacuum residue gasification ash raw material (based on the total weight of the vacuum residue gasification ash raw material, the C content of the vacuum residue gasification ash raw material is 88% by weight, the H content is 5% by weight, the S content is 2% by weight, the N content is 0.5% by weight, the O content is 3% by weight, and the total content of impurity metals is 1.5% by weight). The ash raw material is subjected to hydrometallurgical metal recovery treatment. The specific operation is the same as step (1) in Example 1. Based on the total weight of the gasified ash obtained after the metal removal treatment, the C content of the gasified ash obtained after the metal removal treatment is 88.9% by weight, the H content is 5.1% by weight, the S content is 2% by weight, the N content is 0.7% by weight, the O content is 3.2% by weight, and the total content of impurity metals is 0.1% by weight. The remaining process is also the same as in Example 1, and finally a negative electrode material is prepared.

[0145] Example 7

[0146] This example refers to the preparation method in Example 1, and the difference from Example 1 is:

[0147] In step (6), the mixed liquid is ultrasonically cleaned with an ultrasonic device to perform an alkaline cleaning treatment. The ultrasonic cleaning is performed at a closed constant temperature for 6 hours, the ultrasonic power is 800 W, and the ultrasonic frequency is 40 kHz. The remaining process is the same as in Example 1, and the negative electrode material is finally obtained.

[0148] Example 8

[0149] (1) This embodiment uses the same asphalt ash raw material as in Example 1, and performs the same hydrometallurgical metal recovery treatment on the ash raw material.

[0150] (2) 5 g of the asphalt gasification ash after metal removal was dispersed in 40 mL of ethanol and mixed evenly. The amount of the first ball milling solvent used was 8 mL relative to 1 g of the gasification ash.

[0151] (3) The mixture was placed in a 500 mL zirconia ball mill, and 75 g of 1 mm zirconia beads were added, with a ball-to-material ratio of 15. The mixture was then placed in a planetary ball mill for the first wet milling process, with the mill speed set at 150 rpm, the milling time set at 16 h, and the temperature set at 30°C.

[0152] (4) The suspension after ball milling is subjected to rotary evaporation and drying at a temperature set to 60° C. to obtain the first product.

[0153] (5) The dried powder (first product) was collected and placed in a beaker. 400 ml of 0.5 mol / L potassium hydroxide solution was added. The amount of alkali solution was 80 ml per 1 g of the first product. The mixture was mixed evenly and then subjected to alkali washing.

[0154] (6) The mixed liquid was then stirred using a magnetic stirrer at room temperature, a rotation speed of 800 rpm, and a stirring time of 8 h to obtain a second product.

[0155] (7) After alkali washing, the mixture was filtered and then dried by freeze drying with the temperature set at -60°C, the drying time set at 48h, and the vacuum degree set at 8Pa.

[0156] (8) After the alkaline washing treatment, the powder (second product) was subjected to a second wet ball milling treatment at a speed of 150 rpm, a time of 24 h, and a temperature of 30°C. The solvent used was 750 mL of ethanol. For each gram of the second product, the amount of solvent used in the second ball milling was 150 mL, and 150 g of 1 mm zirconia beads were used, resulting in a ball-to-material ratio of 30.

[0157] (9) After the second wet ball milling treatment is completed, the suspension liquid is spray dried. The spray drying conditions are: inlet temperature of 160°C, outlet temperature of 90°C, feed rate of 10 ml / min, carrier gas flow rate of 15 L / min, inlet pressure of 0.5 MPa, and carrier gas is nitrogen gas to obtain the third product.

[0158] (10) The dried powder (the third product) was placed in an atmosphere furnace for calcination and carbonization. The calcination conditions were as follows: in an Ar atmosphere, the temperature was raised to 600°C at 5°C / min, then kept at this temperature for 2 hours, and then raised to 1500°C at 3°C / min, and kept at this temperature for 2 hours. Finally, the negative electrode material was obtained.

[0159] Example 9

[0160] This example refers to the preparation method in Example 1, and the difference from Example 1 is that the process conditions are changed, specifically including:

[0161] (1) This embodiment uses the same asphalt ash raw material as in Example 1, and performs the same hydrometallurgical metal recovery treatment on the ash raw material.

[0162] (2) 5 g of the asphalt gasification ash after metal removal was dispersed in 80 mL of ethanol and mixed evenly. The amount of the first ball milling solvent used was 16 mL relative to 1 g of the gasification ash.

[0163] (3) The mixture was placed in a 500 mL zirconia ball mill, and 75 g of 1 mm zirconia beads were added, with a ball-to-material ratio of 20. The mixture was then placed in a planetary ball mill for the first wet milling process, with the mill speed set at 280 rpm, the milling time set at 8 h, and the temperature set at 30°C.

[0164] (4) The suspension after ball milling is subjected to rotary evaporation and drying at a temperature set to 60° C. to obtain the first product.

[0165] (5) The dried powder (first product) was collected and placed in a beaker. 300 ml of a 0.5 mol / L potassium hydroxide solution was added and mixed evenly. The mixture was then subjected to an alkali washing treatment. The amount of alkali solution used was 60 ml for every 1 g of the first product.

[0166] (6) The mixed liquid was then stirred using a magnetic stirrer at room temperature, a rotation speed of 500 rpm, and a stirring time of 10 h.

[0167] (7) After alkali washing, the mixture was filtered and then dried by freeze drying with the temperature set at -60°C, the drying time set at 48h, and the vacuum degree set at 8Pa.

[0168] (8) The freeze-dried powder (second product) was subjected to a second wet ball milling process at a speed of 500 rpm, a time of 5 h, and a temperature of 30°C. The solvent was 500 mL of ethanol. The amount of solvent used in the second ball milling was 100 mL per 1 g of the second product, and 60 g of 1 mm zirconia beads were used, resulting in a ball-to-material ratio of 12.

[0169] (9) After the second wet ball milling treatment is completed, the suspension liquid is spray dried. The spray drying conditions are: inlet temperature of 160°C, outlet temperature of 90°C, feed rate of 10 ml / min, carrier gas flow rate of 15 L / min, inlet pressure of 0.5 MPa, and carrier gas is nitrogen gas to obtain the third product.

[0170] (10) The dried powder (the third product) was placed in an atmosphere furnace for calcination and carbonization. The calcination conditions were as follows: in an Ar atmosphere, the temperature was raised to 750°C at a rate of 5°C / min, then kept at this temperature for 2 h, and then raised to 1400°C at a rate of 3°C / min, and kept at this temperature for 2 h. Finally, the negative electrode material was obtained.

[0171] Comparative Example 1

[0172] This comparative example refers to the preparation method in Example 1, and differs from Example 1 in that no alkaline washing or water washing treatment is performed (i.e., no surface deacidification treatment is performed), and the remaining processes are the same as in Example 1, and finally a negative electrode material is obtained.

[0173] Comparative Example 2

[0174] This comparative example refers to the preparation method in Example 1, but differs from Example 1 in that no calcination treatment is performed. The remaining processes are the same as those in Example 1, and finally a negative electrode material is obtained.

[0175] Comparative Example 3

[0176] The comparative example was prepared according to the preparation method in Example 1, except that the second wet ball milling treatment and the spray drying treatment were not performed, and the rest of the process was the same as in Example 1, and finally a negative electrode material was obtained.

[0177] Comparative Example 4

[0178] The comparative example was prepared according to the preparation method in Example 1, except that the bituminous coal gasification slag was replaced by coal tar gasification slag, and the rest of the process was the same as in Example 1, and finally a negative electrode material was obtained.

[0179] The composition and structure parameters of the negative electrode materials prepared in the above examples and comparative examples are listed in Table 1 below.

[0180] Table 1

[0181]

[0182] Test Example 1

[0183] This test example is used to illustrate the electrochemical performance of the products obtained in the examples and comparative examples as negative electrode materials for sodium ion batteries.

[0184] Sodium ion batteries were assembled using the products obtained in the examples and comparative examples as negative electrodes, and their electrochemical performance was tested, with the specific steps being as follows:

[0185] (1) The products (negative electrode materials) obtained in the above examples and comparative examples were respectively mixed with Super-P (a conductive carbon black material), CMC (carboxymethyl cellulose, a dispersing agent) and SBR (styrene-butadiene rubber, a binder) in a mass ratio of 92:3:2:3 (1:0.0326:0.0217:0.0326) in a vacuum homogenizer for 4 h, and then coated on a copper current collector and dried in a vacuum oven at 120°C for 8 h to obtain negative electrode sheets.

[0186] (2) The negative electrode sheets prepared were used as the negative electrodes of the batteries, a metal sodium sheet was used as the positive electrode, glass fiber was selected as the separator, and 1 mol / L NaPF6 (the solvent was diethylene glycol dimethyl ether, DEGDME) was used as the electrolyte, and a coin half-battery was assembled in a glove box.

[0187] Test Example 2

[0188] The negative electrode material prepared in Example 1 was used to assemble a battery according to the method in Test Example 1, except that the ether electrolyte was replaced by an ester electrolyte (1 mol / L NaPF6 in DEC:EC = 1:1 Vol%), and the rest of the process was the same as in Test Example 1.

[0189] Test Example 3

[0190] The negative electrode material prepared in Example 4 was used to assemble a battery according to the method in Test Example 1. The difference from Test Example 1 was that the ether electrolyte was replaced with an ester electrolyte (1 mol / L NaPF6 in DEC:EC=1:1 Vol%), and the rest of the process was the same as Test Example 1.

[0191] The batteries obtained in Test Examples 1-3 were subjected to charge and discharge tests using a BlueDian system. The parameters were: a current density of 0.1C for the first cycle, followed by varying rates (0.2C, 0.5C, and 1.0C), and a voltage range of 0.001 to 3.0V. The test results are listed in Table 2 below.

[0192] Table 2

[0193]

[0194]

[0195] By comparing the data of Test Example 1 and Test Example 2 of the sodium ion battery negative electrode material, it can be found that the first coulombic efficiency in the ester electrolyte is low, only 23.5%, while the use of the ether electrolyte can reach a first coulombic efficiency of 88.1%.

[0196] By comparing the battery data of the negative electrode materials prepared in Example 1 and Example 4 in Test Example 1, it can be found that the negative electrode material modified by coating the gasified ash with phenolic resin has basically no effect on the capacity; further Figure 4 and Figure 5 It can be seen that the rate performance of the negative electrode material provided in the present application in ether electrolyte is significantly better than that in ester electrolyte; Figure 6 After high-rate charge and discharge, the battery specific capacity of the two negative electrode materials prepared in Example 1 and Example 4 increased, showing a higher sodium storage capacity.

[0197] It can be seen from the performance of the negative electrode materials in Test Example 2 and Test Example 3 that after the gasification ash is coated and modified with phenolic resin, the first coulombic efficiency is increased from 23.5% in Test Example 2 (the negative electrode material is not coated and modified with phenolic resin) to 43.6% in Test Example 3 (the negative electrode material is coated and modified with phenolic resin).

[0198] By comparing the data of the negative electrode materials provided in Example 1 and Comparative Example 1 in Test Example 1, it can be seen that the lack of treatment of the gasified ash in Comparative Example 1 will reduce the performance of the prepared negative electrode material when used as a negative electrode material for a sodium ion battery. Among them, if alkaline washing or water washing is not performed to remove the residual acid on the surface of the gasified ash after metal removal, the resulting negative electrode material has almost no capacity (the first charge specific capacity and the first discharge specific capacity are low). This shows that the sodium ion battery negative electrode material prepared in the embodiment using the method provided by the present disclosure as a raw material for gasified ash after metal removal exhibits a high first coulombic efficiency and specific capacity in an ether electrolyte.

[0199] Comparing Example 1 with Example 9, it can be seen that in Example 1, the optimized process conditions provided by the present disclosure are used to prepare the negative electrode material. Compared with Example 9, the sodium ion battery using the negative electrode material prepared in Example 1 in Test Example 1 exhibits higher first coulombic efficiency and specific capacity.

[0200] Comparing Example 8 with Example 9, Example 9 prepared the negative electrode material according to the condition range provided in the present disclosure. Compared with Example 8, the sodium ion battery in Test Example 1 using the negative electrode material prepared in Example 9 showed higher first coulombic efficiency and specific capacity.

[0201] Comparing Example 1 with Example 5, it can be seen that Example 1 adopts a two-stage roasting process, and Example 5 adopts a one-stage roasting process. Compared with Example 5, the sodium ion battery using the negative electrode material prepared in Example 1 in Test Example 1 shows higher first coulombic efficiency and specific capacity.

[0202] The preferred embodiments of the present disclosure are described in detail above. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

[0203] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0204] In addition, the various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for preparing a negative electrode material for a sodium ion battery, characterized in that: The following steps are involved: S1. performing a first ball milling process on gasified ash to obtain a first product, wherein the gasified ash comprises ash produced during heavy oil gasification; the gasified ash is prepared by subjecting the ash raw material to an acidification decomposition treatment to remove metals; S2, performing a surface deacidification treatment on the first product to obtain a second product; S3, subjecting the second product to a second wet ball milling process and a spray drying process to obtain a third product; S4, calcining the third product.

2. The method according to claim 1, characterized in that The metal removal process is a hydrometallurgical metal recovery process.

3. The method according to claim 2, characterized in that The conditions for the hydrometallurgical metal recovery process include: The ash raw material is dried and dehydrated and then crushed to a particle size within the range of 10 to 100 μm to obtain a crushed ash raw material; the crushed ash raw material is mixed with an acid solution and then subjected to an acid hydrolysis treatment under stirring and reflux; the product obtained by the acid hydrolysis treatment is filtered to obtain a gasified ash with metal removed.

4. The method according to claim 3, characterized in that The acid solution is selected from one or more of hydrochloric acid, sulfuric acid and nitric acid; the mixing weight ratio of the acid solution to the crushed ash raw material is 1-20:

1.

5. The method according to claim 4, characterized in that The acid solution is selected from sulfuric acid and / or hydrochloric acid; the mixing weight ratio of the acid solution to the crushed ash raw material is 2-10:

1.

6. The method according to claim 3, characterized in that The stirring reflux temperature is room temperature or 45-100° C., and the acid hydrolysis treatment time is 3-6 hours.

7. The method according to claim 3, characterized in that The ash raw material is selected from one or more of vacuum residue oil gasification ash, residue oil hydrocracking tail oil gasification ash, deoiled asphalt gasification ash, catalytic oil slurry ash and ethylene tar ash.

8. The method according to claim 3, characterized in that Based on the total weight of the ash raw material, the C content in the ash raw material is 82-92 weight%, the H content is 1-10 weight%, the S content is 0.1-5 weight%, the N content is 0.1-5 weight%, the O content is 0.1-5 weight%, and the total content of impurity metals is 0.1-5 weight%, and the impurity metals include Ni, Mo, V, Fe, Na and Ga.

9. The method according to claim 8, characterized in that Based on the total weight of the gasification ash obtained after the metal removal treatment, the C content in the gasification ash obtained after the metal removal treatment is 84-92 weight%, the H content is 1-6 weight%, the S content is 0.1-5 weight%, the N content is 0.1-3 weight%, the O content is 0.1-5 weight%, and the total content of impurity metals is 0.1-3 weight%.

10. The method according to claim 1, characterized in that The conditions of the first ball milling treatment include dry ball milling treatment and / or a first wet ball milling treatment.

11. The method according to claim 10, characterized in that The conditions of the first ball milling treatment include a first wet ball milling treatment.

12. The method according to claim 11, characterized in that The conditions of the first wet ball milling treatment include: a ball milling speed of 200-1000 rpm; a ball milling time of 0.5-12 h; a ball milling temperature of 10-50° C.; a ball-to-material ratio of 1-40; an amount of the first ball milling solvent relative to 1 g of the gasified ash is 10-200 mL; and the first ball milling solvent is selected from one or more of ethanol, nitrogen methyl pyrrolidone, cyclohexane, sulfolane, and tetrahydrofuran.

13. The method according to claim 12, characterized in that The conditions of the first wet ball milling treatment include: a ball milling speed of 300-800 rpm; a ball milling time of 2-6 hours; a ball milling temperature of 20-40° C.; a ball-to-material ratio of 10-30; and an amount of the first ball milling solvent of 20-100 mL relative to 1 g of the gasified ash.

14. The method according to claim 11, characterized in that The method further comprises: drying the product obtained by wet ball milling by rotary evaporation.

15. The method according to claim 14, characterized in that The conditions for the rotary evaporation include: a temperature of 40-200°C.

16. The method according to claim 15, characterized in that The conditions for the rotary evaporation include: a temperature of 40-120°C.

17. The method according to claim 10, characterized in that The conditions of the dry ball milling treatment include: a ball milling speed of 200-450 rpm; a ball milling time of 1-8 hours; a ball milling temperature of 10-50° C.; and a ball-to-material ratio of 1-40.

18. The method according to claim 17, characterized in that The conditions of the dry ball milling treatment include: a ball milling speed of 250-350 rpm; a ball milling time of 2-6 hours; a ball milling temperature of 20-40° C.; and a ball-to-material ratio of 10-30.

19. The method according to claim 1, wherein In step S2, the surface deacidification treatment is a water washing treatment or an alkali washing treatment; the water washing treatment and the alkali washing treatment are independently carried out by stirring cleaning or ultrasonic cleaning.

20. The method according to claim 19, characterized in that The conditions of the water washing treatment include: contacting the first product with deionized water, then stirring and filtering to obtain a filter residue; repeating the process for more than three times to obtain a second product.

21. The method according to claim 20, characterized in that The weight ratio of deionized water to the first product is 1-50:1; the stirring conditions include: a stirring speed of 100-1000 rpm and a stirring time of 2-12 hours.

22. The method according to claim 21, characterized in that The weight ratio of deionized water to the first product is 10-20:1; the stirring conditions include: a stirring speed of 200-400 rpm and a stirring time of 4-8 hours.

23. The method according to claim 19, wherein The conditions for the alkali washing treatment include: an alkali solution concentration of 0.1 to 10 mol / L; the alkali solution is selected from an aqueous alkali solution; the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium bicarbonate and sodium carbonate; and the amount of the alkali solution used is 1 to 100 mL relative to 1 g of the first product.

24. The method according to claim 23, wherein The conditions for the alkali washing treatment include: the concentration of the alkali solution is 0.1-5 mol / L; the amount of the alkali solution is 10-50 mL relative to 1 g of the first product.

25. The method according to claim 19, wherein When stirring cleaning is adopted, the stirring temperature is 20~60°C, the stirring speed is 200~600rpm, and the stirring time is 1~12h.

26. The method according to claim 25, characterized in that When stirring cleaning is adopted, the stirring temperature is 20~40°C, the stirring speed is 200~450rpm, and the stirring time is 2~8h.

27. The method according to claim 19, wherein When ultrasonic cleaning is used, the ultrasound is carried out in a closed constant temperature environment, the ultrasound time is 3 to 8 hours, the ultrasound power is 600 to 3000W, and the ultrasound frequency is 20 to 80KHz.

28. The method according to claim 27, characterized in that When ultrasonic cleaning is used, the ultrasonic time is 3~7h, the ultrasonic power is 400~1000W, and the ultrasonic frequency is 40~60KHz.

29. The method according to claim 1, wherein In step S3, the conditions of the second wet ball milling process include: The ball milling speed is 200-1000 rpm; the ball milling time is 1-12 h; the ball milling temperature is 10-50° C.; the ball-to-material ratio is 1-40; the amount of the second ball milling solvent used is 10-100 mL relative to 1 g of the second product; and the second ball milling solvent is selected from one or more of ethanol, nitrogen methyl pyrrolidone, cyclohexane, sulfolane, and tetrahydrofuran.

30. The method according to claim 29, wherein In step S3, the conditions of the second wet ball milling process include: The ball milling speed is 600-900 rpm; the ball milling time is 6-12 h; the ball milling temperature is 20-40° C.; the ball-to-material ratio is 15-30; and the amount of the second ball milling solvent used is 20-100 mL relative to 1 g of the second product.

31. The method according to claim 1, wherein In step S3, the conditions of the spray drying treatment include: a feed temperature of 120-200°C, an outlet temperature of 80-100°C, a carrier gas flow rate of 12-20 L / min, an inlet pressure of 0.3-0.8 MPa, and the carrier gas is selected from one or more of nitrogen and argon.

32. The method according to claim 31, characterized in that In step S3, the conditions of the spray drying process include: The feed temperature is 140~190℃, the outlet temperature is 90~100℃, the carrier gas flow rate is 14~18L / min, and the inlet pressure is 0.4~0.6MPa.

33. The method according to claim 1, wherein During the second wet ball milling process, a coating modifier is added to coat and modify the gasification ash.

34. The method according to claim 33, wherein The coating modifier is selected from one or more of phenolic resin, epoxy resin, polyfurfuryl alcohol resin and polyethylene.

35. The method according to claim 33, wherein The weight ratio of the coating modifier to the second product is 0.02~0.2:

1.

36. The method according to claim 35, characterized in that The weight ratio of the coating modifier to the second product is 0.05-0.15:

1.

37. The method according to claim 1, wherein In step S4, the calcination treatment conditions include: heating to 600-1500° C. in an inert gas atmosphere and keeping the temperature for 1-6 hours.

38. The method according to claim 37, wherein In step S4, the calcination treatment conditions include: heating to 750-1300° C. in an inert gas atmosphere and keeping the temperature for 1-6 hours.

39. The method according to claim 37, wherein In step S4, the calcination treatment conditions include: a heating rate of 0.5-5°C / min.

40. The method according to claim 39, wherein In step S4, the calcination treatment conditions include: a heating rate of 1-3°C / min.

41. The method according to claim 1, wherein In step S4, the calcination treatment conditions include: in an inert gas atmosphere, first heating to 700-1000°C at a first heating rate, keeping warm for 1-6 hours, then heating to 1000-1700°C at a second heating rate, keeping warm for 1-6 hours.

42. The method according to claim 41, wherein In step S4, the calcination treatment conditions include: in an inert gas atmosphere, first heating to 800-1000°C at a first heating rate, keeping warm for 2-4 hours, then heating to 1000-1300°C at a second heating rate, keeping warm for 2-4 hours.

43. The method according to claim 41, wherein In step S4, the calcination treatment conditions include: the first heating rate is 1-10°C / min, and the second heating rate is 1-7°C / min.

44. The method according to claim 43, wherein In step S4, the conditions of the calcination treatment include: the first heating rate is 1-5°C / min, and the second heating rate is 1-3°C / min.

45. The method according to claim 37 or 41, characterized in that In step S4, the inert gas is selected from one or more of nitrogen, helium, and argon; the water content of the inert gas is less than 0.1 wt%, and the oxygen content is less than 0.1 wt%.

46. ​​A negative electrode material for a sodium ion battery prepared according to the method of any one of claims 1 to 45.

47. The negative electrode material according to claim 46, characterized in that Based on the total weight of the negative electrode material, the carbon content is greater than 90 weight%, the hydrogen content is less than 3 weight%, and the content of other impurity elements is less than 7 weight%, wherein the other impurity elements include one or more of sulfur, nitrogen, oxygen and impurity metals, and the impurity metals include Ni, Mo, V, Fe, Na and Ga.

48. The negative electrode material according to claim 46, characterized in that The negative electrode material D 50 Particle size is 1~50μm, BET specific surface area is 1~500m 2 / g.

49. The negative electrode material according to claim 48, characterized in that The average particle size of the negative electrode material is 5-12 μm, and the BET specific surface area is 1-200 m 2 / g.

50. A negative electrode plate for a sodium ion battery, characterized in that: Contains the negative electrode material according to any one of claims 46 to 49.

51. The negative electrode plate according to claim 50, characterized in that: The negative electrode sheet is prepared by a method comprising the following steps: preparing the negative electrode material into a negative electrode slurry, coating the slurry on the surface of a negative electrode current collector, and performing a drying process to obtain the negative electrode sheet.

52. The negative electrode plate according to claim 51, characterized in that: The negative electrode slurry includes the negative electrode material, a conductive material, a dispersant, and a binder.

53. The negative electrode plate according to claim 52, characterized in that: The weight ratio of the negative electrode material: the conductive material: the dispersant: the binder is 60-96: 0.01-5: 1-10: 1-10.

54. The negative electrode plate according to claim 53, characterized in that: The weight ratio of the negative electrode material: the conductive material: the dispersant: the binder is 80-96: 0.02-10: 1-5: 1-5.

55. The negative electrode plate according to claim 52, characterized in that: The conductive agent material is selected from one or more of highly conductive carbon black, conductive graphite, acetylene black, Ketjen black, single-walled carbon nanotubes, multi-walled carbon nanotubes and carbon nanofibers.

56. The negative electrode plate according to claim 52, characterized in that: The dispersant is selected from one or more of carboxymethyl cellulose, sodium carboxymethyl cellulose, hydroxyethyl cellulose, sodium alginate, polyvinyl alcohol, chitosan and beta-cyclodextrin.

57. The negative electrode plate according to claim 52, characterized in that: The binder is selected from one or more of styrene-butadiene copolymer, polyacrylic acid, sodium polyacrylate, polyimide, polyvinylidene fluoride, nitrile rubber, butadiene rubber, xanthan gum and gum arabic.

58. A sodium ion battery, characterized in that The sodium ion battery comprises a positive electrode sheet, a negative electrode sheet as described in any one of claims 50 to 57, a battery separator and an electrolyte.

59. The sodium ion battery according to claim 58, characterized in that The electrolyte is selected from one or more of ester electrolytes, ether electrolytes and sulfone electrolytes.

60. The sodium ion battery according to claim 59, characterized in that The ester electrolyte is selected from one or more of ethylene carbonate, vinylene carbonate, vinyl ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate and fluorocarbonate.

61. The sodium ion battery according to claim 59, characterized in that The ether electrolyte is selected from one or more of 1,3-dioxolane, 1,4-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1H, 1H, 5H-octafluoropentyl-1, 1, 2, 2-tetrafluoroethyl ether, perfluorohexane, 1,2-bis(cyanoethoxy)ethane and 1, 1, 2, 2-tetrafluoroethyl-2, 2, 3, 3-tetrafluoropropyl ether.

62. The sodium ion battery according to claim 59, characterized in that The sulfone electrolyte is selected from one or more of dimethyl sulfoxide, tetramethylene sulfone, ethyl methyl sulfone, tetramethyl sulfone, sulfolane and methoxyethyl methyl sulfone.

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