Artificial graphite material and preparation method thereof, negative plate, electrochemical device and electronic equipment

Abstract

The invention discloses an artificial graphite material and a preparation method thereof, a negative plate, an electrochemical device and electronic equipment. The artificial graphite material meets the following conditions: the crushing coefficient P is 0.70-0.85, P = A / B, A and B are respectively the specific surface areas of the artificial graphite material before and after powder pressing, and the powder pressing pressure is 5t; the volume specific surface area S is 1.80-2.65 m < 2 > / cm < 3 >; and the lattice spacing d is in a range of 0.3370 to 0.3410 nm. The preparation method of the artificial graphite material provided by the invention realizes low-cost recovery of the graphite material in the waste battery, and the prepared artificial graphite material has excellent cycle performance and storage performance.

Description

Technical Field

[0001] This invention relates to artificial graphite materials and their preparation methods, negative electrode sheets, electrochemical devices, and electronic devices. Background Technology

[0002] Graphite is an important anode material for lithium-ion batteries, and it is generally divided into artificial graphite and natural graphite. Artificial graphite is derived from petrochemical byproducts and requires high-temperature graphitization for production. This entire process is energy-intensive and highly polluting, placing significant pressure on power supplies. Natural graphite comes from natural mineral deposits, has a relatively limited production volume, and has other important applications, such as metal smelting and nuclear energy. Therefore, the effective recycling of graphite resources has received widespread attention.

[0003] Currently, graphite resource recycling mainly refers to recovering graphite materials from the negative electrode sheets of used batteries. Recycling methods typically include acid methods and high-temperature methods (>1600℃), which are costly and highly polluting, often accompanied by a significant decline in material performance. For example, Chinese patent CN117865145 A uses secondary high-temperature graphitization and coating to repair and recycle graphite, which is extremely costly; Chinese patent CN116375022A uses an acid method, resulting in a significant increase in BET (Bio-Electro ... Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing technologies in recovering graphite materials from waste batteries, namely high costs and severe performance degradation. It provides artificial graphite materials, their preparation methods, negative electrode sheets, electrochemical devices, and electronic devices. The artificial graphite material preparation method provided by this invention achieves low-cost recovery of graphite materials from waste batteries, and the resulting artificial graphite material exhibits excellent cycle performance and storage performance.

[0005] In a first aspect, the present invention provides an artificial graphite material, wherein the artificial graphite material satisfies the following conditions:

[0006] The breakage coefficient P is 0.70-0.85, P=A / B, where A and B are the specific surface areas of the artificial graphite material before and after powder pressing, and the pressure of powder pressing is 5t;

[0007] The specific surface area S is 1.80-2.65 m². 2 / cm 3 ;

[0008] The lattice spacing d is 0.3370-0.3410 nm.

[0009] Secondly, the present invention provides a method for preparing an artificial graphite material, the method comprising the following steps:

[0010] S1. A mixture comprising recycled graphite powder and secondary graphite is subjected to a first shaping process to obtain product I; the secondary graphite accounts for 25%-40% of the mass of the recycled graphite powder; the compacted density of the secondary graphite powder is 1.4-1.5 g / cc; the first rotational speed R1 of the first shaping process is 2500 r / min - 3500 r / min;

[0011] S2. The product I is subjected to a “heating-first heat preservation-cooling-second heat preservation” cycle treatment and a second shaping process to obtain the artificial graphite material; the second rotation speed R2 of the second shaping is 6000 r / min - 8000 r / min; the cooling rate is 40-65℃ / min.

[0012] Thirdly, the present invention provides an artificial graphite material, which is prepared by the artificial graphite material preparation method described above.

[0013] Fourthly, the present invention provides a negative electrode sheet comprising the artificial graphite material as described above.

[0014] Fifthly, the present invention provides an electrochemical device comprising the artificial graphite material as described above or the negative electrode as described above.

[0015] In a sixth aspect, the present invention provides an electronic device comprising the electrochemical device as described above.

[0016] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0017] The reagents and raw materials used in this invention are all commercially available.

[0018] The positive and progressive effects of this invention are as follows:

[0019] The present invention provides a method for preparing artificial graphite materials, which recovers graphite materials from the negative electrode sheets of waste batteries. The method is simple, efficient, easy to operate, and low in cost. The artificial graphite materials recovered by the present invention have a breakage coefficient, volumetric surface area, and lattice spacing within a certain range, exhibiting excellent cycle performance and storage performance. Detailed Implementation

[0020] The first aspect of the present invention provides an artificial graphite material, wherein the artificial graphite material satisfies the following conditions:

[0021] The breakage coefficient P is 0.70-0.85, P=A / B, where A and B are the specific surface areas of the artificial graphite material before and after powder pressing, and the pressure of powder pressing is 5t;

[0022] The specific surface area S is 1.80-2.65 m². 2 / cm 3 ;

[0023] The lattice spacing d is 0.3370-0.3410 nm.

[0024] In this invention, the breakage coefficient P reflects the degree of fragmentation of the powder under extreme pressure. The closer the value is to 1.0, the less likely the material is to break. The test method is the ASTM D6556 multi-point BET method (77K nitrogen adsorption). First, the original specific surface area of ​​the artificial graphite material is measured and recorded as A; then, the powder is pressed under a pressure of 5t, and the specific surface area is measured again and recorded as B. P = A / B.

[0025] In this invention, the volumetric surface area S reflects the reactivity ratio per unit volume of the artificial graphite material under actual application conditions. A larger volumetric surface area indicates a higher reactivity ratio per unit volume and poorer storage performance, while a smaller volumetric surface area indicates insufficient kinetics. The volumetric surface area is the product of the mass surface area and the bulk density. The test method for the mass surface area refers to the national standard GB / T 19587-2017, and the test method for the bulk density refers to the national standard GB / T 1479.1-2011.

[0026] In this invention, the lattice spacing reflects the ease with which lithium ions are embedded in artificial graphite materials. A smaller lattice spacing indicates poorer kinetics and higher repair costs, while a larger lattice spacing indicates more defects, which is detrimental to storage performance. The test method for lattice spacing refers to the national standard GB / T 24533-2019.

[0027] In this invention, the breakage coefficient P can be 0.75-0.82.

[0028] In some specific implementations, the breakage coefficient P can be 0.72, 0.75, 0.77, 0.8, 0.82 or 0.85.

[0029] In this invention, the volumetric surface area S can be 1.80-2.65 m². 2 / cm 3 The optimal depth is 2.0-2.4 m. 2 / cm 3 More preferably 2.2-2.4 m 2 / cm 3 .

[0030] In some specific implementations, the volumetric surface area S can be 1.8 m². 2 / cm 3 1.9 m 2 / cm 3 2 m2 / cm 3 2.3 m 2 / cm 3 2.4 m 2 / cm 3 2.5 m 2 / cm 3 or 2.65 m 2 / cm 3 .

[0031] In some specific embodiments, the lattice spacing d may be 0.337 nm, 0.3378 nm, 0.338 nm, 0.3385 nm, 0.3393 nm, 0.34 nm or 0.3405 nm.

[0032] In some specific embodiments, the artificial graphite material satisfies the following conditions: a breakage coefficient P of 0.77 and a volumetric surface area S of 2.30 m². 2 / cm 3 The lattice spacing d is 0.3385 nm.

[0033] In some specific embodiments, the artificial graphite material meets the following conditions: a breakage coefficient P of 0.82 and a volumetric surface area S of 1.90 m². 2 / cm 3 The lattice spacing d is 0.3378 nm.

[0034] In some specific embodiments, the artificial graphite material meets the following conditions: a breakage coefficient P of 0.85 and a volumetric surface area S of 1.80 m². 2 / cm 3 The lattice spacing d is 0.3393 nm.

[0035] In some specific embodiments, the artificial graphite material meets the following conditions: a breakage coefficient P of 0.72 and a volumetric surface area S of 2.50 m². 2 / cm 3 The lattice spacing d is 0.3405 nm.

[0036] In some specific embodiments, the artificial graphite material meets the following conditions: a fragmentation coefficient P of 0.80 and a volumetric surface area S of 2.00 m². 2 / cm 3 The lattice spacing d is 0.3380 nm.

[0037] In some specific embodiments, the artificial graphite material meets the following conditions: a fragmentation coefficient P of 0.75 and a volumetric surface area S of 2.40 m². 2 / cm 3The lattice spacing d is 0.3400 nm.

[0038] In some specific embodiments, the artificial graphite material meets the following conditions: a breakage coefficient P of 0.85 and a volumetric surface area S of 2.30 m². 2 / cm 3 The lattice spacing d is 0.3385 nm.

[0039] In some specific embodiments, the artificial graphite material meets the following conditions: a breakage coefficient P of 0.77 and a volumetric surface area S of 2.65 m². 2 / cm 3 The lattice spacing d is 0.3385 nm.

[0040] In some specific embodiments, the artificial graphite material satisfies the following conditions: a breakage coefficient P of 0.77 and a volumetric surface area S of 2.30 m². 2 / cm 3 The lattice spacing d is 0.3370 nm.

[0041] In this invention, the artificial graphite material exists at least partially in the form of single particles.

[0042] In this invention, the artificial graphite material can be obtained by the method for recycling artificial graphite material from waste batteries as described in the second aspect.

[0043] The second aspect of this invention provides a method for preparing artificial graphite material, the method comprising the following steps:

[0044] S1. A mixture comprising recycled graphite powder and secondary graphite is subjected to a first shaping process to obtain product I; the secondary graphite accounts for 25%-40% of the mass of the recycled graphite powder; the compacted density of the secondary graphite powder is 1.4-1.5 g / cc; the first rotational speed R1 of the first shaping process is 2500 r / min - 3500 r / min;

[0045] S2. The product I is subjected to a “heating-first heat preservation-cooling-second heat preservation” cycle treatment and a second shaping process to obtain the artificial graphite material; the second rotation speed R2 of the second shaping is 6000 r / min - 8000 r / min; the cooling rate is 40-65℃ / min.

[0046] In this invention, the recycled graphite powder can be derived from the negative electrode sheet of a waste battery.

[0047] In some implementations, the method for obtaining the graphite recycled powder from the negative electrode sheet of the waste battery includes: first treating the negative electrode sheet of the waste battery with ultraviolet light, sieving, collecting the sieve material and washing it with water; wherein the ultraviolet light intensity is 90μW / cm²-150μW / cm², and the treatment temperature is 30-45℃.

[0048] The sieving can be performed using methods conventional in the art. Preferably, the sieving is a vibrating sieve. Preferably, the mesh size of the sieve used is 30 mesh.

[0049] The number of times the water is washed is preferably 3 times.

[0050] The intensity of the ultraviolet light is preferably 120 μW / cm².

[0051] The preferred processing temperature is 37°C.

[0052] In this invention, the graphite recycling powder may include single-particle graphite, and the proportion of single-particle graphite in the graphite recycling powder may be 50%-100%, for example 80%.

[0053] In this invention, the carbon content of the recycled graphite powder can be greater than 98%.

[0054] In this invention, the secondary graphite refers to recycled graphite material obtained from used graphite products (such as graphite electrodes, battery negative electrodes, thermal field components, etc.) through recycling, purification, and reprocessing. The secondary graphite used in the preparation method of this invention can be commercially available secondary graphite, secondary graphite obtained through other recycling methods, or artificial graphite material obtained by the preparation method of this invention, meaning that one batch of artificial graphite material is used as another batch of "secondary graphite".

[0055] In this invention, the compaction density of the secondary graphite powder is preferably 1.4-1.47 g / cc, for example 1.4 g / cc or 1.47 g / cc.

[0056] In this invention, preferably, the secondary graphite accounts for 25%-35% of the mass of the recycled graphite powder.

[0057] In some specific implementations, the secondary graphite accounts for 30% or 40% of the mass of the recycled graphite powder.

[0058] In step S1, the first shaping can be performed in an air jet mill.

[0059] In step S1, the temperature of the first shaping can be 400℃-500℃, for example, 500℃. The main purpose of heating in the first shaping is to remove the water of crystallization adsorbed on the graphite recycled powder.

[0060] In step S1, the first rotational speed R1 can be 2500 r / min - 3300 r / min. The main purpose of controlling the appropriate rotational speed in the first shaping process is to remove the irregular large edges on the surface of the graphite recycled powder.

[0061] In some specific implementations, the first rotational speed R1 may be 3000 r / min, 3300 r / min or 3500 r / min.

[0062] In step S1, the roundness of product I can be 0.41 or higher. The roundness describes the sharpness of the edges of the artificial graphite particles; a higher value indicates a smoother edge. The roundness range is typically 0 to 1, where 0 represents very sharp edges and 1 represents perfectly rounded edges. The testing method is as follows: SEM images of the artificial graphite material are acquired using a scanning electron microscope (SEM), and then the images are analyzed using the Malvern Morphologi 4 software module to obtain the roundness.

[0063] In step S1, the abrasion degree of product I can be 0.48 or higher. Here, abrasion degree describes the degree to which the particles are close to a spherical shape; a higher value indicates a closer approximation to a sphere, and it describes the unevenness of the particle surface. The testing method is as follows: SEM images of the artificial graphite material are acquired using a scanning electron microscope (SEM), and then the images are analyzed using the Malvern Morphologi 4 software module to obtain the abrasion degree.

[0064] In step S1, the breakage coefficient of product I can be 0.55-0.65, for example 0.6.

[0065] In step S1, the lattice spacing of product I can be below 0.345 nm.

[0066] In step S1, the specific surface area of ​​product I can be 3.5 m². 2 / g or less. The specific surface area can be measured using the ASTM D6556 multi-point BET method (77K nitrogen adsorption).

[0067] In step S2, the number of cycles of the "heating-first heat preservation-cooling-second heat preservation" process can be 2-3 times.

[0068] In step S2, the temperature of the first insulation can be 900℃-1100℃, for example, 1000℃.

[0069] In step S2, the first heat preservation time can be 0.5-5 hours, for example, 4 hours.

[0070] In step S2, the heating rate can be 2-5℃ / min, for example 2℃ / min.

[0071] In step S2, the temperature of the second insulation can be 550℃-700℃, for example 600℃.

[0072] In step S2, the second heat preservation time is 1-3 hours, for example, 1 hour.

[0073] In step S2, the cooling rate can be 40-60℃ / min, for example, 40℃ / min, 50℃ / min or 60℃ / min.

[0074] In step S2, the cooling method is to introduce gas for cooling, and the flow rate of the introduced gas can be 80-130 L / min, preferably 90-120 L / min; the gas is preferably nitrogen.

[0075] In some specific embodiments, the flow rate of the introduced gas can be 80 L / min, 100 L / min or 120 L / min;

[0076] In step S2, the temperature of the second shaping can be 550℃-700℃, for example 600℃.

[0077] In step S2, the second rotational speed R2 can be 7000 r / min - 8000 r / min.

[0078] In some specific implementations, the second rotational speed R2 can be 6500 r / min, 7000 r / min, 7600 r / min or 8000 r / min.

[0079] In step S2, the second shaping time can be 1 hour to 3 hours, for example, 1 hour.

[0080] In this invention, after the second shaping, post-processing is performed, which includes one or more of grading, water washing, and demagnetization.

[0081] The particle size distribution width of the artificial graphite material obtained by grading is less than 1.30.

[0082] The particle size of the artificial graphite material obtained by grading satisfies: (Dv90-Dv50 / Dv50-Dv10)>1.6.

[0083] In this invention, the particle size distribution width, Dv10, Dv50, and Dv90 can be obtained by using a conventional laser particle size analyzer in the art.

[0084] The artificial graphite material provided in the third aspect of the present invention is prepared by the artificial graphite material preparation method described above.

[0085] In this invention, the artificial graphite material has the same structural features as the artificial graphite material described in the first aspect.

[0086] The negative electrode provided in the fourth aspect of the present invention comprises the artificial graphite material as described above.

[0087] In this invention, the negative electrode sheet may include a negative electrode current collector and a negative electrode material layer, wherein the negative electrode material layer is disposed on at least one surface of the negative electrode current collector; the negative electrode material layer includes the artificial graphite material as described above.

[0088] In this invention, the negative electrode current collector can be a conventional negative electrode current collector in the art. The negative electrode current collector, serving as the substrate supporting the negative electrode material layer, is typically a metal foil with a thickness of 3-500 μm. There are no particular limitations on the material, as long as it has high conductivity and does not produce a chemical reaction in the secondary battery system. For example, it can be a foil formed by surface treatment of nickel, titanium, aluminum, silver, stainless steel, carbon, etc. The negative electrode current collector usually has a smooth surface, but fine textures can also be formed on its surface to improve the adhesion between the negative electrode material layer and the current collector. Besides foil, the negative electrode current collector can also be used in any one or more combinations of various forms such as film, mesh, porous, foam, or non-woven fabric. Generally, the negative electrode current collector is copper foil.

[0089] In this invention, the negative electrode material layer may further include a conductive agent.

[0090] The conductive agent is not particularly limited, as long as it is conductive and does not cause chemical changes in the battery. For example, specific materials that can be used include: graphite, such as natural or artificial graphite; carbon-based materials, such as conductive carbon black (Super P, abbreviated as SP), carbon nanotubes (CNT), acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, or carbon fiber; metal powders or metal fibers, such as copper, nickel, aluminum, or silver; conductive whiskers, such as zinc oxide whiskers or potassium titanate whiskers; conductive metal oxides, such as titanium dioxide; or conductive polymers, such as polyphenylene derivatives.

[0091] In this invention, the negative electrode material layer may further include a binder.

[0092] The type of adhesive is not particularly limited and can be selected from polyvinylidene fluoride, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid (PAA), ethylene-propylene-diene terpolymer and its sulfonates, styrene-butadiene rubber (SBR), fluororubber and various copolymers, such as SBR.

[0093] In this invention, the negative electrode material layer may further include a thickener.

[0094] The addition of the thickener can increase the viscosity of the system of each component in the negative electrode slurry. It can be a thickener commonly used in the art to prepare negative electrode sheets, such as sodium carboxymethyl cellulose (CMC).

[0095] In some embodiments, the method for preparing the negative electrode sheet includes the following steps: coating a negative electrode slurry containing the artificial graphite material onto at least one surface of the negative electrode current collector, drying, cold pressing, and slitting to obtain the negative electrode sheet.

[0096] In some specific embodiments, the negative electrode slurry includes: the artificial graphite material, a conductive agent, a thickener, and a binder, wherein the conductive agent is acetylene black; the thickener is CMC; and the binder is SBR and PAA; preferably, the mass ratio of the artificial graphite material, acetylene black, CMC, SBR, and PAA is 97.4:0.4:0.4:0.5:1.3.

[0097] The electrochemical device provided in the fifth aspect of the present invention includes the artificial graphite material as described above or the negative electrode as described above.

[0098] In this invention, the electrochemical device is preferably a battery.

[0099] In some embodiments, the electrochemical device is a lithium-ion battery.

[0100] In some embodiments, the lithium-ion battery may be a liquid lithium-ion battery, an all-solid-state lithium-ion battery, or a semi-solid-state lithium-ion battery. The battery type does not limit the scope of protection of this invention.

[0101] In some specific embodiments, the liquid lithium-ion battery includes a positive electrode, a negative electrode as described above, a separator, and an electrolyte.

[0102] In some specific embodiments, the all-solid-state lithium-ion battery includes a positive electrode, a negative electrode as described above, and a solid electrolyte membrane.

[0103] In this invention, the liquid lithium-ion battery includes a positive electrode, a negative electrode as described above, and a separator.

[0104] Positive electrode film

[0105] In this invention, the positive electrode sheet may include a positive current collector and a positive electrode material layer, wherein the positive electrode material layer is disposed on at least one surface of the positive current collector; the positive electrode material layer includes a positive electrode active material.

[0106] In some embodiments, the positive electrode active material may be a positive electrode active material conventionally used in the art, such as one or more of lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, and lithium cobalt oxide.

[0107] In some embodiments, the positive electrode material layer further includes a conductive agent. The conductive agent is a reagent used to ensure that the electrode has good charge-discharge performance. It can be selected from graphite materials such as natural graphite and artificial graphite; carbon black materials such as Super P, conductive carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermally cracked carbon black; conductive fibers such as carbon nanotubes (CNTs), carbon fibers, and metal fibers; metal powders such as fluorinated carbon powder, aluminum powder, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; and conductive metal oxides or polyphenylene derivatives such as titanium dioxide, for example, Super P and CNTs.

[0108] In some embodiments, the positive electrode material layer further includes a binder. The binder may be a component that facilitates the bonding between the positive electrode active material and the conductive agent, and also facilitates the bonding between the positive electrode active material and the positive electrode current collector. It can typically be selected from polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers, such as PVDF.

[0109] In some embodiments, the positive electrode material layer includes a positive electrode active material, Super P, CNT, and PVDF.

[0110] In some specific embodiments, the mass ratio of the positive electrode active material, Super P, CNT and PVDF is 97:1.0:0.5:1.5.

[0111] In this invention, the positive electrode current collector can be a conventional positive electrode current collector in the art. For the positive electrode current collector, materials that do not cause chemical changes and have high conductivity can be used without limitation. For example, commonly used materials include stainless steel, aluminum, nickel, titanium, or calcined carbon, or aluminum or stainless steel materials surface-treated with carbon, nickel, titanium, silver, etc. To enhance adhesion, micro-embossing can be formed on the surface of the positive electrode current collector. The positive electrode current collector can be used in various forms, such as films, sheets, foils, meshes, or porous bodies.

[0112] In some alternative embodiments, the positive current collector is aluminum foil.

[0113] In this invention, the positive electrode sheet can be prepared using methods conventional in the art.

[0114] In some optional embodiments, the method for preparing the positive electrode sheet includes the following steps: mixing the positive electrode active material, binder and conductive agent in a certain mass ratio, adding solvent and mixing evenly to obtain a positive electrode slurry; then uniformly coating the positive electrode slurry onto at least one surface of the positive electrode current collector; and then preparing the positive electrode sheet by drying, rolling, slitting and other processes.

[0115] electrolyte

[0116] In some embodiments, the electrolyte may be a conventional electrolyte used in batteries, typically including non-aqueous solvents and lithium salts.

[0117] In this invention, the non-aqueous solvent can be a conventional non-aqueous solvent in the art.

[0118] In some embodiments, the non-aqueous solvent preferably comprises ester solvents and / or dimethyl sulfoxide (DMSO), more preferably carbonate solvents. The carbonate solvent may optionally be one or more of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), methyl ethyl carbonate (EMC), ethylene carbonate, propylene carbonate, and butyl carbonate (BC). The non-aqueous solvent may also include ethyl acetate.

[0119] In this invention, the lithium salt can be a conventional lithium salt in the art, preferably one or more of LiPF6, LiBF4, LiClO4, LiCF3SO3 and LiN(CF3SO2)2, for example, LiPF6; the concentration of the lithium salt is preferably 1 mol / L.

[0120] In this invention, the electrolyte may include additives, which may be conventional additives in the art, such as fluoroethylene carbonate (FEC).

[0121] In some embodiments, the electrolyte includes LiPF6, ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate.

[0122] In some preferred embodiments, the electrolyte comprises EC, EMC, and DEC. The volume ratio of EC, EMC, and DEC is, for example, 1:1:1.

[0123] In some embodiments, the electrolyte can be prepared by conventional methods in the art. Optionally, it can be prepared by the following method: mixing the various non-aqueous solvents in proportion in an argon atmosphere glove box with a water content of <10 ppm, and then adding a fully dried lithium salt and mixing evenly to obtain the electrolyte.

[0124] diaphragm

[0125] In some alternative embodiments, the diaphragm may be a polypropylene membrane or a polyethylene membrane.

[0126] In some alternative embodiments, the thickness of the diaphragm may be 9 μm-18 μm, for example, 11 μm.

[0127] In some alternative embodiments, the air permeability of the diaphragm can be 180s / 100mL-380s / 100mL.

[0128] In some alternative embodiments, the porosity of the membrane may be 30%-50%.

[0129] In this invention, the method for preparing the lithium-ion battery can be a conventional method in the art. It can be that the positive electrode, separator, and negative electrode are wound in sequence to obtain the battery cell, which is then packaged in a packaging shell and injected with the electrolyte. Alternatively, the positive electrode, separator, and negative electrode are stacked in sequence to obtain the battery cell, which is then packaged in a packaging shell and injected with the electrolyte. After that, the lithium-ion battery is obtained through processes such as settling, hot and cold pressing, formation, clamping, and capacity testing.

[0130] The electronic device provided in the sixth aspect of the present invention includes the electrochemical device as described above.

[0131] For example, the electronic devices described in this invention may be, but are not limited to, mobile devices (such as mobile phones, tablets, laptops, video recorders, portable printers / copiers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems and backup power supplies, etc.

[0132] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0133] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0134] Example 1

[0135] 1. Negative electrode plate

[0136] (1) Preparation of artificial graphite materials

[0137] S0. Preparation of recycled graphite powder: Disassemble waste batteries to obtain negative electrode sheets. First, treat the negative electrode sheets under ultraviolet light at an intensity of 120 μW / cm² and a temperature of 37℃. Then, vibrate and sieve through a 30-mesh screen to collect the undersize material, obtaining primary recycled graphite powder. Wash the powder three times with water to obtain recycled graphite powder with a carbon content greater than 98%, where the carbon content is greater than 98% and the proportion of single-particle graphite is 80%.

[0138] S1. The recovered graphite powder and secondary graphite (Shanghai Shanshan CP5 graphite, compacted density 1.47 g / cc, mass percentage 30%) were added to an air jet mill and heated to 500℃. Simultaneously, the speed of the air jet mill's separator was maintained at the first speed R1 (3000 r / min) for the first shaping process, which lasted 4 hours, yielding product I. Product I has a roundness greater than 0.41, a roughness greater than 0.48, a breakage coefficient of 0.6, and a specific surface area less than 3.5 m². 2 / g, lattice spacing less than 0.345nm;

[0139] S2. The product I obtained in step S1 is heated to 1000℃ at a rate of 2℃ / min and held for 4 hours (first holding). Then, nitrogen is introduced at a flow rate of 100L / min to cool it down to 600℃ (cooling rate of 50℃ / min) and held for 1 hour (second holding). The above "heating-first holding-cooling-second holding" cycle is repeated 3 times. Then, the temperature is maintained at 600℃, and the rotation speed of the separator is adjusted to the second rotation speed R2, which is 7000r / min, for the second shaping, which takes 1 hour. The material obtained from the second shaping is then naturally cooled and then graded to control its particle size distribution width to be less than 1.30 and (Dv90-Dv50 / Dv50-Dv10)>1.6. Then, it is washed with water, dried, and demagnetized to obtain artificial graphite material.

[0140] (2) Preparation of negative electrode

[0141] The prepared artificial graphite material was used as the negative electrode material, acetylene black as the conductive agent, CMC as the thickener, and SBR and PAA as the binder. They were mixed in a mass ratio of 97.4:0.4:0.4:0.5:1.3, and deionized water was added as a solvent. The mixture was stirred thoroughly to obtain a negative electrode slurry. The negative electrode slurry was uniformly coated on one surface of the negative electrode current collector copper foil. After drying, cold pressing, and slitting, a negative electrode sheet was prepared.

[0142] 2. Positive electrode plate

[0143] Lithium iron phosphate (LFP), Super P, CNT, and polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 97:1.0:0.5:1.5, and N-methylpyrrolidone (NMP) was added as a solvent. The mixture was stirred thoroughly to obtain a positive electrode slurry. The positive electrode slurry was coated onto a positive electrode current collector aluminum foil, and the positive electrode sheet was prepared by drying, cold pressing, and slitting.

[0144] 3. Diaphragm

[0145] A porous PE membrane with a thickness of 11 μm was used as the separator.

[0146] 4. Electrolyte

[0147] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0148] 5. Lithium-ion batteries

[0149] The positive electrode, separator, and negative electrode prepared in the aforementioned steps are stacked sequentially, with the separator positioned between the positive and negative electrode to act as a separator. Then, an aluminum-plastic film is wrapped around the separator, dried, and the electrolyte prepared above is injected. After encapsulation, settling, and formation processes, a soft-pack battery with a designed capacity of 1 Ah, i.e., a lithium-ion battery, is finally prepared.

[0150] Examples 2-9 and Comparative Examples 1-9

[0151] Some process parameters of each embodiment and comparative example are shown in Table 1. Other unlisted process parameters and preparation methods are the same as in Example 1.

[0152] Example 2 differs from Example 1 in that the mass ratio of secondary graphite is adjusted to 40%, while the other steps and process conditions are the same as in Example 1.

[0153] Example 3 differs from Example 1 in that the compaction density of the secondary graphite is adjusted to 1.4 g / cc, while the other steps and process conditions are the same as in Example 1.

[0154] Example 4 differs from Example 1 in that the first rotational speed R1 is adjusted to 3300 r / min, while the other steps and process conditions are the same as in Example 1.

[0155] Example 5 differs from Example 1 in that the second rotational speed R2 is adjusted to 7600 r / min, while the other steps and process conditions are the same as in Example 1.

[0156] Example 6 differs from Example 1 in that the nitrogen flow rate is adjusted to 120 L / min (cooling rate is 60 °C / min), while the other steps and process conditions are the same as in Example 1.

[0157] Example 7 differs from Example 1 in that the mass ratio of secondary graphite is adjusted to 40%, the first rotation speed R1 is adjusted to 3500 r / min, and the second rotation speed R2 is adjusted to 8000 r / min. Other steps and process conditions are the same as in Example 1.

[0158] The difference between Example 8 and Example 1 is that the first rotational speed R1 is adjusted to 3500 r / min and the second rotational speed R2 is adjusted to 6500 r / min at the same time. The other steps and process conditions are the same as in Example 1.

[0159] Example 9 differs from Example 1 in that the nitrogen flow rate is adjusted to 80 L / min (cooling rate is 40 °C / min), while the other steps and process conditions are the same as in Example 1.

[0160] The difference between Comparative Example 1 and Example 1 is that the mass ratio of secondary graphite is adjusted to 50%, while the other steps and process conditions are the same as in Example 1.

[0161] The difference between Comparative Example 2 and Example 1 is that the compaction density of the secondary graphite was adjusted to 1.3 g / cc, while the other steps and process conditions were the same as in Example 1.

[0162] The difference between Comparative Example 3 and Example 1 is that the first rotational speed R1 is adjusted to 1500 r / min, while the other steps and process conditions are the same as in Example 1.

[0163] The difference between Comparative Example 4 and Example 1 is that the second rotational speed R2 is adjusted to 8500 r / min, while the other steps and process conditions are the same as in Example 1.

[0164] The difference between Comparative Example 5 and Example 1 is that the nitrogen flow rate was adjusted to 160 L / min (the cooling rate was 80 °C / min), while the other steps and process conditions were the same as in Example 1.

[0165] The difference between Comparative Example 6 and Example 1 is that the mass ratio of secondary graphite is adjusted to 20%, the compaction density of secondary graphite is adjusted to 1.5 g / cc, the first rotation speed R1 is adjusted to 3500 r / min, and the flow rate is adjusted to 110 L / min (cooling rate is 55℃ / min). Other steps and process conditions are the same as in Example 1.

[0166] The difference between Comparative Example 7 and Example 1 is that the mass ratio of secondary graphite is adjusted to 50%, the compaction density of secondary graphite is adjusted to 1.45 g / cc, the first rotation speed R1 is adjusted to 2000 r / min, and the nitrogen flow rate is adjusted to 120 L / min (the cooling rate is 60℃ / min). Other steps and process conditions are the same as in Example 1.

[0167] The difference between Comparative Example 8 and Example 1 is that the mass ratio of secondary graphite is adjusted to 50% and the compaction density of secondary graphite is adjusted to 1.6 g / cc. Other steps and process conditions are the same as in Example 1.

[0168] The difference between Comparative Example 9 and Example 1 is that the mass ratio of secondary graphite is adjusted to 10%, the first rotation speed R1 is adjusted to 4500 r / min, and the nitrogen flow rate is adjusted to 120 L / min (the cooling rate is 60℃ / min). Other steps and process conditions are the same as in Example 1.

[0169] Table 1

[0170] serial number Secondary graphite mass percentage Secondary graphite compaction density (g / cc) R1(r / min) Nitrogen flow rate (L / min) Cooling rate (°C / min) R2(r / min) Example 1 30% 1.47 3000 100 50 7000 Example 2 40% 1.47 3000 100 50 7000 Example 3 30% 1.4 3000 100 50 7000 Example 4 30% 1.47 3300 100 50 7000 Example 5 30% 1.47 3000 100 50 7600 Example 6 30% 1.47 3000 120 60 7000 Example 7 40% 1.47 3500 100 50 8000 Example 8 30% 1.47 3500 100 50 6500 Example 9 30% 1.47 3000 80 40 7000 Comparative Example 1 50% 1.47 3000 100 50 7000 Comparative Example 2 30% 1.3 3000 100 50 7000 Comparative Example 3 30% 1.47 1500 100 50 7000 Comparative Example 4 30% 1.47 3000 100 50 8500 Comparative Example 5 30% 1.47 3000 160 80 7000 Comparative Example 6 20% 1.5 3500 110 55 7000 Comparative Example 7 50% 1.45 2000 120 60 7000 Comparative Example 8 50% 1.6 3000 100 50 7000 Comparative Example 9 10% 1.47 4500 120 60 7000

[0171] Example 1: Material Characterization

[0172] The artificial graphite materials and intermediate products obtained in Examples 1-9 and Comparative Examples 1-9 were characterized as follows:

[0173] 1. Crushing coefficient

[0174] The ASTM D6556 multi-point BET method (77K nitrogen adsorption) was used. First, the original specific surface area of ​​the sample was measured and denoted as A. Then, the sample was subjected to powder compression at a pressure of 5t (holding pressure for 30s), and the specific surface area was measured again and denoted as B. The breakage coefficient P = A / B. The test results are shown in Table 2.

[0175] 2. Specific surface area

[0176] The volumetric surface area is the product of the mass surface area and the bulk density; the test method for the mass surface area is in accordance with the national standard GB / T 19587-2017, and the test method for the bulk density is in accordance with the national standard GB / T 1479.1-2011. The test results are shown in Table 2.

[0177] 3. Lattice spacing

[0178] The test method for lattice spacing was performed in accordance with the national standard GB / T 24533-2019. The test results are shown in Table 2.

[0179] 4. Roundness R

[0180] SEM images of the samples were acquired using a scanning electron microscope (SEM, JEOL JSM-7610FPlus) at 2000x magnification, and then analyzed using the Malvern Morphologi 4 software module. At least 30 particles were selected from different regions of the SEM images, and each particle was tested individually. The average value was taken as the final roundness R.

[0181] 5. Grinding convexity S

[0182] SEM images of the samples were acquired using a scanning electron microscope (SEM, JSM-7610FPlus, NEC). The images were then analyzed using the Malvern Morphologi 4 software module. At least 30 particles were selected from different regions of the SEM images, and each particle was tested individually. The average value was taken as the final abrasion degree S.

[0183] 6. Carbon content

[0184] The carbon content in the graphite recycled powder obtained in step S0 was tested, and the test method was in accordance with GB / T 3521-2023.

[0185] 7. Percentage of single-particle graphite

[0186] The proportion of single-particle graphite in the graphite recycled powder obtained in step S0 was tested. The specific test method was as follows:

[0187] Disperse 1g of powder sample thoroughly in ethanol and drop it onto conductive adhesive; spray carbon to ensure the sample surface is conductive and avoid the charging effect from affecting image quality.

[0188] SEM images of the samples were obtained using a scanning electron microscope (SEM, JSM-7610FPlus, manufactured by Nippon Electron, model JSM-7610FPlus) at a magnification of 2000x, and at least 100 particles were selected.

[0189] The ImageJ software module was used to analyze the images, identify "single particles" and "agglomerates", count the number of particles, and calculate the proportion of single particles.

[0190] Table 2

[0191] serial number Crushing coefficient P <![CDATA[Volume specific surface area S (m 2 / cm 3 )]]> Lattice spacing d (nm) Example 1 0.77 2.30 0.3385 Example 2 0.82 1.90 0.3378 Example 3 0.85 1.80 0.3393 Example 4 0.72 2.50 0.3405 Example 5 0.80 2.00 0.3380 Example 6 0.75 2.40 0.3400 Example 7 0.85 2.30 0.3385 Example 8 0.77 2.65 0.3385 Example 9 0.77 2.30 0.3370 Comparative Example 1 0.88 1.60 0.3358 Comparative Example 2 0.9 1.70 0.3363 Comparative Example 3 0.92 1.70 0.3367 Comparative Example 4 0.65 2.90 0.3376 Comparative Example 5 0.55 3.40 0.3425 Comparative Example 6 0.65 2.30 0.3385 Comparative Example 7 0.90 2.30 0.3385 Comparative Example 8 0.77 1.70 0.3385 Comparative Example 9 0.77 2.70 0.3385

[0192] After preparing 1Ah lithium-ion pouch batteries using the examples and comparative examples, activation and capacity testing were performed. The activation and capacity testing process included cycling the prepared lithium-ion batteries three times at a current of 0.5Ah within a voltage range of 2.5-3.65V, and recording the average discharge capacity of the three cycles as C. Then, the following tests were performed:

[0193] Example 2: Cyclic Performance Test

[0194] 1. Capacity retention rate during room temperature cycling

[0195] The lithium-ion batteries prepared in Examples 1-9 and Comparative Examples 1-9 were cycled at 0.5C and 2.5-3.65V under 25°C conditions. After 3000 cycles, the discharge capacity of the battery at this point was divided by the discharge capacity of the first cycle to obtain the battery's capacity retention rate after 3000 cycles. The results are recorded in Table 3.

[0196] 2. High-temperature cycling capacity retention

[0197] The lithium-ion batteries prepared in Examples 1-9 and Comparative Examples 1-9 were cycled at 45°C using a charge-discharge cycle of 1C and 2.5-3.65V. After 2000 cycles, the discharge capacity of the battery at this point was divided by the discharge capacity of the first cycle to obtain the battery's capacity retention rate after 2000 cycles. The results are recorded in Table 3.

[0198] Example 3: Storage Performance Test

[0199] At 25°C, the lithium-ion batteries prepared in Examples 1-9 and Comparative Examples 1-9 were subjected to a 0.33C current for capacity determination, denoted as C0. The batteries were then stored at a high temperature of 60°C. Every 7 days thereafter, the batteries were taken out and their capacity was tested at room temperature, denoted as C1, C2, ..., Cn. The number of days until Cn first fell below 80% of C0 was used as the standard for measuring storage capacity. The results are recorded in Table 3.

[0200] Table 3

[0201] serial number Room temperature cycling capacity retention (%) High-temperature cycling capacity retention (%) Storage days (days) Example 1 96.9 95.3 469 Example 2 96.5 95.1 420 Example 3 95.7 94.9 406 Example 4 95.4 94.1 385 Example 5 96.5 95.2 448 Example 6 95.5 94.3 399 Example 7 96.8 94.2 455 Example 8 95.8 95.0 413 Example 9 96.1 95.1 427 Comparative Example 1 95.1 93.8 364 Comparative Example 2 94.7 93.9 336 Comparative Example 3 94.9 93.3 322 Comparative Example 4 94.3 93.1 343 Comparative Example 5 93.5 91.3 294 Comparative Example 6 93.8 91.2 315 Comparative Example 7 93.6 92.6 280 Comparative Example 8 95.2 94.1 315 Comparative Example 9 91.8 89.2 315

[0202] As can be seen from the data in the table above, the lithium-ion battery made from the artificial graphite material recovered from waste batteries in this invention has excellent storage and cycle performance. Specifically, at a high temperature of 60°C, the storage period can reach more than 380 days; the capacity retention rate during room temperature cycling (3000 cycles) is more than 95%, and the capacity retention rate during high temperature cycling (2000 cycles) is more than 94%. Furthermore, the recycling method of this invention is simple, easy to implement, and low in cost.

[0203] In Comparative Examples 1-9, some process parameters during the preparation of artificial graphite materials were outside the scope of this invention, and the fragmentation coefficient P, specific surface area S, and lattice spacing d of the obtained artificial graphite materials could not simultaneously meet the requirements of this invention. When the artificial graphite materials in Comparative Examples 1-9 were applied to lithium-ion batteries, their storage performance deteriorated significantly, and their cycle performance at both room temperature and high temperature also decreased.

[0204] The proportion of secondary graphite in Comparative Example 1 is greater than the range of the present invention; the compaction density of secondary graphite in Comparative Example 2 is less than the range of the present invention; the first rotational speed R1 in Comparative Example 3 is less than the range of the present invention; the breakage coefficient P, volumetric surface area S, and lattice spacing d of the artificial graphite materials prepared in Comparative Examples 1-3 are all outside the range of the present invention, wherein the breakage coefficient P is too large, the volumetric surface area S and the lattice spacing d are too small, and the cycle performance and storage performance of the lithium-ion batteries prepared are deteriorated to varying degrees.

[0205] In Comparative Example 4, the second rotational speed R2 is greater than the range of the present invention. The resulting artificial graphite material has a small breakage coefficient P and a large volumetric surface area S, which reduces the cycle performance and storage performance of the resulting lithium-ion battery.

[0206] The nitrogen flow rate in Comparative Example 5 was greater than that of the present invention, resulting in an artificial graphite material with a low breakage coefficient P, excessively large volumetric surface area S and lattice spacing d, and a significant decrease in its cycle performance and storage performance.

[0207] In Comparative Example 6, the secondary graphite mass ratio was too small, resulting in a low breakage coefficient P for the obtained artificial graphite material; in Comparative Example 7, the secondary graphite mass ratio was too large, resulting in a high breakage coefficient P for the obtained artificial graphite material; in Comparative Example 8, the secondary graphite mass ratio was too large and the compaction density of the secondary graphite was too high, resulting in a low volumetric surface area S for the obtained artificial graphite material; in Comparative Example 9, the secondary graphite mass ratio was too small, resulting in a high volumetric surface area S for the obtained artificial graphite material. The resulting lithium-ion batteries exhibited poor cycle performance and storage performance.

[0208] The possible reasons are as follows: if the breakage coefficient P is too large, it indicates that the surface of the artificial graphite material still contains hard shell material generated during the graphitization process, which will worsen the material compaction and increase the number of amorphous defects, thus affecting performance; if P is too small, it indicates that the material has poor sphericity, is prone to stress concentration, is easily broken, and has weak resistance to deformation. Both excessively large and excessively small values ​​are detrimental to the storage performance and cycle performance of lithium-ion batteries.

[0209] If the volumetric surface area S is too small, it means that the specific reactivity per unit volume is too small, resulting in insufficient kinetics when applied to batteries. If S is too large, it means that the specific reactivity per unit volume is larger, and the storage performance is worse.

[0210] A small lattice spacing d indicates poor kinetics and is detrimental to cycle performance. A d similar to that of TEDA indicates that the graphite material has too many defects, which is detrimental to storage performance.

[0211] It is evident that P, S, and d must simultaneously satisfy the scope of this invention in order to possess good technology.

[0212] The difference between Example 1 and Example 2 lies in the different mass ratio of secondary graphite. It can be seen that, within a certain range, choosing a lower amount of secondary graphite in combination with other features is beneficial to improving the cycle performance and storage performance of artificial graphite materials.

[0213] The difference between Example 1 and Example 3 lies in the compaction density of the secondary graphite. It can be seen that, within a certain range, selecting secondary graphite with a higher compaction density and combining it with other features is beneficial to improving the cycle performance and storage performance of artificial graphite materials.

[0214] The difference between Example 1 and Example 4 lies in the different first rotational speed R1. It can be seen that, within a certain range, selecting a lower first rotational speed R1 in combination with other features is beneficial to improving the cycle performance and storage performance of artificial graphite materials, especially the storage performance.

[0215] The difference between Example 1 and Example 5 lies in the different second rotational speed R2. It can be seen that, within a certain range, selecting a lower second rotational speed R2 in combination with other features can improve the cycle performance and storage performance to a certain extent.

[0216] The difference between Example 1 and Example 6 lies in the nitrogen flow rate, i.e. the cooling rate. It can be seen that, within a certain range, selecting a lower cooling rate in combination with other features can improve the cycle performance and storage performance to a certain extent, especially the storage performance, which can be significantly improved.

[0217] Compared to Example 1, Example 7 changed several process parameters, resulting in a higher breakage coefficient of the artificial graphite material; compared to Example 1, Example 8 changed several process parameters, resulting in a higher volumetric surface area of ​​the artificial graphite material; compared to Example 1, Example 9 changed the nitrogen flow rate, resulting in a lower lattice spacing d of the artificial graphite material. The storage and cycle performance of the resulting lithium-ion batteries varied. Within a certain range, a lower breakage coefficient P, a higher volumetric surface area S, and a higher lattice spacing d are beneficial to improving cycle performance and storage performance.

[0218] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A synthetic graphite material, characterized by, The artificial graphite material satisfies the following conditions: a broken coefficient P of 0.70-0.85, P=A / B, wherein A and B are specific surface areas before and after powder pressing of the artificial graphite material, wherein the powder pressing pressure is 5t; The volume specific surface area S is 1.80-2.65 m 2 / cm 3 ; a lattice spacing d of 0.3370-0.3410nm.

2. The artificial graphite material according to claim 1, characterized by The artificial graphite material satisfies one or more of the following conditions a-c: a. a broken coefficient P of 0.75-0.82; b. The volume specific surface area S is 2.2 - 2.4 m 2 / cm 3 ; c. the artificial graphite material exists at least partially in a single particle form.

3. A method for producing an artificial graphite material, characterized by, The preparation method of the artificial graphite material comprises the following steps: S1. performing first shaping on a mixture comprising graphite recovery powder and secondary graphite, to obtain product I; the mass proportion of the secondary graphite in the graphite recovery powder is 25%-40%; the powder compaction density of the secondary graphite is 1.4-1.5g / cc; the first rotating speed R1 of the first shaping is 2500r / min-3500r / min; S2. sequentially performing "temperature increase-first holding-temperature decrease-second holding" cycle processing and second shaping on the product I, to obtain the artificial graphite material; the second rotating speed R2 of the second shaping is 6000r / min-8000r / min; the temperature decrease rate is 40-65℃ / min.

4. The method for producing an artificial graphite material according to claim 3, characterized by, Step S1 satisfies one or more of the following conditions a-i: a. the first rotating speed R1 is 2500r / min-3300r / min; b. the temperature of the first shaping is 400℃-500℃; c. the powder compaction density of the secondary graphite is 1.4-1.47g / cc; d. the mass proportion of the secondary graphite in the graphite recovery powder is 25%-35%; e. the sphericity of the product I is 0.41 or more; f. the convexity of the product I is 0.48 or more; g. the broken coefficient P of the product I is 0.55-0.65; h. the lattice spacing d of the product I is 0.345nm or less; i. the specific surface area S of the product I is 3.5 m 2 / g.

5. The method of producing an artificial graphite material according to claim 3, characterized by, Step S2 satisfies one or more of the following conditions a-j: a. the cycle number of the "temperature increase-first holding-temperature decrease-second holding" cycle processing is 2-3 times; b. the temperature of the first holding is 900℃-1100℃; c. the time of the first holding is 0.5-5h; d. the temperature increase rate is 2-5℃ / min; e. the temperature of the temperature decrease is 550℃-700℃; f. the time of the second holding is 1-5h; g. the temperature decrease mode is cooling by gas input, and the flow rate Q of the gas input is 90-120L / min; h. the temperature of the second shaping is 550℃-700℃; i. the second rotating speed R2 is 7000r / min-8000r / min; j. the time of the second shaping is 1h-3h.

6. The method of producing an artificial graphite material according to claim 3, characterized by, The preparation method satisfies one or more of the following conditions a-d: a. The graphite recycled powder is derived from waste batteries, and a preparation method of the graphite recycled powder comprises: irradiating and treating a negative electrode sheet of a waste battery under ultraviolet light, sieving, and collecting undersize for water washing; wherein the ultraviolet light intensity is 90-150 μW / cm2, and the treatment temperature is 30-45 ℃; b. The graphite recycled powder comprises single-particle graphite; c. The carbon content of the graphite recycled powder is greater than 98%; d. The second shaping is followed by post-treatment, and the post-treatment comprises one or more of grading, water washing, and magnetic removal.

7. An artificial graphite material, characterized by, It is prepared by the method of claim 3-6.

8. A negative electrode sheet characterized by comprising: It comprises the artificial graphite material of any one of claims 1-2 and 7.

9. An electrochemical device, characterized by, It comprises the artificial graphite material of any one of claims 1-2 and 7 or the negative electrode sheet of claim 8.

10. An electronic device, comprising: It comprises the electrochemical device of claim 9.