A production method for preparing the negative electrode material of a lithium-ion battery using leftover materials

Abstract

A production method for preparing the negative electrode material of a lithium-ion battery using waste materials, comprising the following steps: uniformly mixing waste material A and binder B to obtain precursor C; performing a shaping treatment on precursor C to obtain precursor D; performing a carbonization treatment on precursor D to obtain semi-coked material E; performing a crushing and shaping treatment on E to obtain material F; uniformly mixing F and binder B to obtain precursor G; putting G into a reaction kettle and performing a heat treatment under a nitrogen atmosphere to obtain precursor H; performing graphitization on the precursor H to obtain material I; uniformly mixing material I, conductive agent J, and binder B in a mixer to obtain material K; performing a carbonization treatment on material K to obtain material L; uniformly mixing, screening, and demagnetizing material L to obtain the negative electrode material. The technical solution provided by the present invention realizes the efficient utilization of waste materials, and the obtained negative electrode material can meet the application requirements in terms of specific capacity, tap density, and rate performance.

Description

Technical Field

[0001] The present invention relates to the technical field of anode materials for lithium-ion batteries, and particularly to a production method for preparing anode materials for lithium-ion batteries using tailings. Background Art

[0002] During the process of manufacturing anode materials for lithium-ion batteries using raw materials such as coke and graphite, usually 5% - 40% of tailings (D50 ≤ 5μm) are generated. Due to their small particle size, high specific surface area, low tap density, poor morphology, and difficulty in shaping, they cannot be directly used in the production of anode materials for lithium-ion batteries and are usually used as low-value fuels and carbon agents, greatly reducing the utilization rate of raw materials and invisibly increasing the production cost of anode materials for lithium-ion batteries. With the booming development of the new energy industry, the demand for anode materials for lithium-ion batteries has increased significantly, and the problem of rational utilization of tailings has become increasingly prominent. Therefore, recycling tailings to enable the production of anode materials for lithium-ion batteries with the same performance has very positive significance.

[0003] CN10476695A discloses a method for recycling artificial graphite fine powder as an anode material, which includes the following steps: Step A: Using the "tailings" generated during the production of artificial graphite anode materials for lithium batteries as raw materials, adding a binder and a pore-forming agent, kneading and granulating at a certain temperature, then rolling or pressing, and carbonizing at a high temperature; Step B: Crushing and shaping and spheroidizing the carbonized material to obtain graphite powder that meets the particle size range requirements; then performing high-temperature graphitization, and at the same time, the "tailings" collected during the crushing / spheroidizing process can be added to Step A as raw materials for recycling; Step C: Adjusting the particle size of the graphitized powder and filling the gaps between the particles by physical mixing to improve its bulk density. Although this solution can utilize the "tailings" generated during the production of artificial graphite anode materials for lithium batteries, in this patent, graphite: binder: pore-forming agent = 100: 0.1 - 0.4: 0.01 - 0.1, and the proportion of the binder is relatively low, which cannot effectively bond the graphite tailings and is easily scattered into tailings again during the subsequent crushing process. Therefore, although it can utilize the "tailings" to a certain extent, the utilization efficiency is low. At the same time, the types of tailings in this patent are limited to graphite, the applicable range is low, and the electrochemical performance of the obtained anode material needs to be further improved.

[0004] CN112875696A discloses a preparation method of a low-cost and high-rate graphite-like anode material based on carbon material tailings, comprising the following steps: S1 collecting tailing A during the front-end processing of crushing or shaping carbon materials; S2 performing classification processing on tailing A to obtain precursor B; S3 performing heat treatment on precursor B in a reaction kettle under a nitrogen atmosphere to obtain precursor C; S4 graphitizing precursor C, and after graphitization, it is GC; S5 putting GC and resin into a high-speed VC mixer to mix and obtain material D; S6 putting material D into a high-temperature carbonization device and performing carbonization treatment under nitrogen protection to obtain a modified carbonized anode material E; S7 screening with an ultrasonic vibrating screen to obtain material F; S8 mixing with a V-type mixer to obtain material G; S9 demagnetizing with a demagnetizer to obtain finished product H; the graphite anode material obtained by this solution can be applied in the fast charging field, but the material B after classification treatment is directly subjected to heat treatment without using auxiliary materials such as binders and coating agents, so that it can only be applied to tailing raw materials with high volatile matter. For tailings with low volatile matter, it is equivalent to directly graphitizing the tailings after classification, and the lithium-ion anode material prepared in this way needs to be further improved in terms of processing performance and electrical performance. Summary of the Invention

[0005] The present invention aims to solve at least one defect existing in the prior art. To this end, the technical problem solved by the present invention is to propose a production method for preparing a lithium-ion battery anode material using various coke or graphite tailings, and the obtained anode material can meet the application requirements of mainstream lithium-ion batteries in terms of specific capacity, tap density, and rate performance.

[0006] To solve the above technical problems, the production method for preparing a lithium-ion battery anode material using tailings provided by the present invention includes the following steps:

[0007] 1) Mixing 100 parts by mass of tailing A with 5 - 35 parts by mass of binder B in a mixer to obtain precursor C;

[0008] 2) Performing forming treatment on precursor C to obtain precursor D;

[0009] 3) Performing carbonization treatment on precursor D at a temperature of 300 - 500 °C under a nitrogen atmosphere to obtain semi-coked material E;

[0010] 4) Crushing and shaping semi-coked material E to obtain material F; the secondary tailings formed during the crushing and shaping process are returned to step 1) for recycling;

[0011] 5) Mixing 100 parts by mass of material F with 5 - 20 parts by mass of binder B in a mixer to obtain precursor G;

[0012] 6) Put the precursor G into the reactor and conduct heat treatment under a nitrogen atmosphere to obtain the precursor H; the heat treatment temperature is 550 - 700 °C, the heating rate of the reactor is 2 - 10 °C / min, and the stirring speed is 15 - 40 r / min;

[0013] 7) Disintegrate and classify the precursor H, and select the precursor H with a particle size D50 of 10 - 20 μm and D90 not exceeding 40 μm for graphitization to obtain the material I; the graphitization temperature is 2800 - 3300 °C, and the graphitization time is 24 - 48 h; the tertiary tailings formed during the disintegration and classification process are returned to step 1) for recycling;

[0014] 8) Mix 100 parts by mass of the material I, 0.1 - 5 parts by mass of the conductive agent J, and 1 - 10 parts by mass of the binder B evenly in a mixer to obtain the material K; the conductive agent J includes one or a mixture of two or more of carbon nanotubes, carbon black, acetylene black, and Ketjen black;

[0015] 9) Conduct carbonization treatment on the material K at a temperature of 900 - 1300 °C under a nitrogen atmosphere to obtain the material L; the heating rate during the carbonization treatment in this step is 1 - 5 °C / min;

[0016] 10) Prepare the negative electrode material after mixing, screening, and demagnetization treatment of the material L;

[0017] The tailing A is coke tailing or graphite tailing generated during the production of the graphite negative electrode material; the particle size D50 of the tailing A ≤ 5 μm;

[0018] The binder B includes one or a mixture of two or more of medium-temperature pitch, high-temperature pitch, modified pitch, mesophase pitch, phenolic resin, and epoxy resin;

[0019] Furthermore, in the improved technical solution, the production method for preparing the negative electrode material of the lithium-ion battery using the tailing provided by the present invention, the mixer includes a V-type high-efficiency mixer, a fusion machine, a twin-screw conical mixer, a conical high-speed mixer, a ribbon mixer, and a gravity-free mixer.

[0020] Furthermore, in the improved technical solution, the production method for preparing the negative electrode material of the lithium-ion battery using the tailing provided by the present invention, the forming treatment in step 2) includes isostatic pressing, molding pressing, extrusion molding, and granulator molding, and the molding pressure is 20 - 200 MPa.

[0021] Furthermore, in the improved technical solution, the production method for preparing the negative electrode material of the lithium-ion battery using the tailing provided by the present invention, the volatile content of the semi-coked material E prepared by the carbonization treatment in step 3) is 1 wt% - 10 wt%.

[0022] Further improved technical solution, for the production method of preparing the negative electrode material of the lithium ion battery using the tail material provided by the present invention, the equipment used for carbonization treatment to prepare the semi-coked material E in step 3) includes a baking furnace, a carbonization furnace, a roasting furnace, a pusher furnace, a tunnel kiln, a shaft furnace, and an Acheson furnace.

[0023] Further improved technical solution, for the production method of preparing the negative electrode material of the lithium ion battery using the tail material provided by the present invention, the equipment used for carbonization treatment in step 9) includes a high-temperature carbonization furnace, a pusher furnace, a roller hearth kiln, and a tunnel kiln.

[0024] Further improved technical solution, for the production method of preparing the negative electrode material of the lithium ion battery using the tail material provided by the present invention, the particle size D of the material F 50 is 6 - 12 μm, and those with a particle size lower than 2 μm and exceeding 25 μm do not exceed 10 wt%.

[0025] Further improved technical solution, for the production method of preparing the negative electrode material of the lithium ion battery using the tail material provided by the present invention, the tail material A includes one or a mixture of two or more of petroleum coke tail material, needle coke tail material, pitch coke tail material, and natural graphite tail material.

[0026] The technical solution provided by the present invention regenerates the tail material into a semi-coked material through processing means such as forming and low-temperature carbonization using the coke tail material or graphite tail material recovered during the production of the graphite negative electrode material. After carbonization treatment of the semi-coking, since the binder B is already in a semi-coked state, the whole material retains 1 wt% - 10 wt% of volatile matter, the bonding force between the tail material A and the binder B is enhanced, and the bonding state of the material is similar to that of the raw material of coke, and various physical indexes are also extremely close. The semi-coked material E is not easily broken into smaller particle-size materials during the powder grinding and shaping processes, but forms solid integral particles; at the same time, due to the forming treatment, the material is densely filled, and the pores and cavities between the materials are filled with the binder, so that the tapped density of the material is greatly improved, even higher than that of the raw material coke. After the semi-coked material E is pulverized, shaped, and mixed with the binder B, secondary granulation is carried out through a reaction kettle to make the material form a larger isotropic particulate matter. Lithium ions can enter the graphite interlayer from the channels in all directions, and due to the appropriate particle size of the particulate matter, the diffusion path of lithium ions is greatly reduced, and the prepared negative electrode material exhibits excellent rate performance; a conductive agent is added during the secondary coating process to enhance the conductivity of the negative electrode material, reduce the battery polarization, and increase the specific capacity.

[0027] The technical solution provided by the present invention realizes the efficient utilization of various coke or graphite tail materials generated during the production of the graphite negative electrode, is easy to industrialize, can improve the utilization rate of raw materials, and reduce production costs. The obtained negative electrode material can meet the application requirements of mainstream lithium ion batteries in terms of specific capacity, tap density, and rate performance. Embodiment

[0028] The present invention will be further described below in conjunction with the embodiments. Example 1

[0029] The process of using tailings to prepare negative electrode materials for lithium-ion batteries includes the following steps:

[0030] 1) 100 parts by mass of tailings A and 5 parts by mass of medium-temperature asphalt are mixed evenly in a V-type high-efficiency mixer to obtain a precursor C; in this embodiment, tailings A are tailings generated in the process of producing graphite negative electrode materials, and tailings A use petroleum coke tailings with a particle size of D50≤5μm.

[0031] 2) Precursor C is statically pressed to obtain precursor D; the molding pressure is 20 MPa.

[0032] 3) The precursor D is carbonized in a baking furnace at a temperature of 300° C. under a nitrogen atmosphere to obtain a semi-coked material E with a volatile matter of 10 wt %.

[0033] 4) The semi-coked material E is crushed and shaped to obtain material F; the secondary tailings formed during the crushing and shaping process are returned to step 1) for recycling. The particle size of the material F is D 50 The particle size is 6 μm, of which the particle size below 2 μm and above 25 μm does not exceed 10 wt %.

[0034] 5) 100 parts by mass of material F and 5 parts by mass of medium-temperature asphalt are mixed evenly in a mixer to obtain precursor G.

[0035] 6) Precursor G is placed in a reactor and heat treated in a nitrogen atmosphere to obtain precursor H; the heat treatment temperature is 550° C., the reactor heating rate is 2° C. / min, and the stirring speed is 15 r / min.

[0036] 7) The precursor H is broken up and classified, and the precursor H with a particle size D50 of 10 μm and a D90 of no more than 40 μm is selected for graphitization to obtain material I; the graphitization temperature is 2800° C., and the graphitization time is 48 h; the tertiary tailings formed during the breaking up and classification process are returned to step 1) for recycling.

[0037] 8) 100 parts by mass of material I, 0.1 parts by mass of carbon nanotubes, and 10 parts by mass of medium-temperature asphalt are mixed uniformly in a mixer to obtain material K.

[0038] 9) Carbonizing material K in a tunnel kiln at a temperature of 900°C and a nitrogen atmosphere to obtain material L; the heating rate during the carbonization treatment in this step is 1°C / min;

[0039] 10) The material L is mixed, screened, and demagnetized to obtain the negative electrode material. Example 2

[0040] The process of using tailings to prepare negative electrode materials for lithium-ion batteries includes the following steps:

[0041] 1) 100 parts by mass of tailings A and 35 parts by mass of high-temperature asphalt are mixed evenly in a fusion machine to obtain a precursor C; in this embodiment, tailings A are tailings generated in the process of producing graphite negative electrode materials, and tailings A use needle-shaped coke tailings with a particle size of D50≤5μm.

[0042] 2) Precursor C is compression molded to obtain precursor D; the compression molding pressure is 200 MPa.

[0043] 3) The precursor D is carbonized in a carbonization furnace at a temperature of 500° C. under a nitrogen atmosphere to obtain a semi-coked material E having a volatile matter of 1 wt %.

[0044] 4) The semi-coked material E is crushed and shaped to obtain material F; the secondary tailings formed during the crushing and shaping process are returned to step 1) for recycling. The particle size of the material F is D 50 The particle size is 12 μm, of which the particle size below 2 μm and above 25 μm does not exceed 10 wt %.

[0045] 5) 100 parts by mass of material F and 20 parts by mass of high-temperature asphalt are mixed evenly in a mixer to obtain precursor G.

[0046] 6) Precursor G is placed in a reactor and heat treated under a nitrogen atmosphere to obtain precursor H; the heat treatment temperature is 700° C., the reactor heating rate is 10° C. / min, and the stirring speed is 40 r / min.

[0047] 7) The precursor H is broken up and classified, and the precursor H with a particle size D50 of 20 μm and a D90 of no more than 40 μm is selected for graphitization to obtain material I; the graphitization temperature is 3300° C., and the graphitization time is 24 hours; the tertiary tailings formed during the breaking up and classification process are returned to step 1) for recycling.

[0048] 8) 100 parts by mass of material I, 5 parts by mass of carbon black, and 1 part by mass of high-temperature asphalt are mixed uniformly in a mixer to obtain material K;

[0049] 9) Carbonizing material K in a high temperature carbonization furnace at a temperature of 1300°C and a nitrogen atmosphere to obtain material L; the heating rate during the carbonization treatment in this step is 5°C / min;

[0050] 10) The material L is mixed, screened, and demagnetized to obtain the negative electrode material. Example 3

[0051] The process of preparing the anode material for lithium-ion batteries using tailings includes the following steps:

[0052] 1) Mix 100 parts by mass of tailing A with 22 parts by mass of phenolic resin in a conical high-speed mixer to obtain precursor C; in this example, tailing A is the tailing generated during the production of the graphite anode material, and the asphalt coke tailing with a particle size of D50 ≤ 5 μm is used for tailing A.

[0053] 2) Extrude precursor C to obtain precursor D; the forming pressure is 110 MPa.

[0054] 3) Carbonize precursor D in a roasting furnace at a temperature of 400 °C under a nitrogen atmosphere to obtain semi-coked material E with a volatile content of 6 wt%.

[0055] 4) Crush and shape semi-coked material E to obtain material F; the secondary tailings formed during the crushing and shaping process are returned to step 1) for recycling. The particle size D of material F 50 is 9 μm, and those with a particle size below 2 μm and exceeding 25 μm do not exceed 10 wt%.

[0056] 5) Mix 100 parts by mass of material F with 12 parts by mass of epoxy resin in a mixer to obtain precursor G.

[0057] 6) Put precursor G into a reaction kettle and perform heat treatment under a nitrogen atmosphere to obtain precursor H; the heat treatment temperature is 625 °C, the heating rate of the reaction kettle is 6 °C / min, and the stirring speed is 28 r / min.

[0058] 7) Disintegrate and classify precursor H, and select precursor H with a particle size D50 of 15 μm and D90 not exceeding 40 μm for graphitization to obtain material I; the graphitization temperature is 3050 °C, and the graphitization time is 36 h; the tertiary tailings formed during the disintegration and classification process are returned to step 1) for recycling.

[0059] 8) Mix 100 parts by mass of material I, 2.6 parts by mass of acetylene black, and 6 parts by mass of phenolic resin in a mixer to obtain material K.

[0060] 9) Carbonize material K in a roller hearth kiln at a temperature of 1100 °C under a nitrogen atmosphere to obtain material L; the heating rate during the carbonization process in this step is 3 °C / min;

[0061] 10) Mix, screen, and demagnetize material L to obtain the anode material. Example 4

[0062] The process of preparing the anode material for lithium-ion batteries using tailings includes the following steps:

[0063] 1) Mix 100 parts by mass of tail material A and 20 parts by mass of binder B evenly in a gravity-free mixer to obtain precursor C. In this example, tail material A is the tail material generated during the production of graphite anode materials, and tail material A uses natural graphite tail material with a particle size D50 ≤ 5 μm. Binder B uses 50wt% modified pitch and 50wt% mesophase pitch.

[0064] 2) Granulate precursor C using a granulator to obtain precursor D; the forming pressure is 130 MPa.

[0065] 3) Carbonize precursor D in a pit furnace under a nitrogen atmosphere at a temperature of 450 °C to obtain semi-coked material E with a volatile content of 5wt%.

[0066] 4) Crush and shape semi-coked material E to obtain material F; the secondary tail material formed during the crushing and shaping process is returned to step 1) for recycling. The particle size D of material F 50 is 10 μm, and those with a particle size below 2 μm and exceeding 25 μm do not exceed 10wt%.

[0067] 5) Mix 100 parts by mass of material F and 15 parts by mass of binder B evenly in a mixer to obtain precursor G. Binder B uses epoxy resin. Binder B uses 50wt% modified pitch and 50wt% mesophase pitch.

[0068] 6) Put precursor G into a reaction kettle and perform heat treatment under a nitrogen atmosphere to obtain precursor H; the heat treatment temperature is 630 °C, the heating rate of the reaction kettle is 8 °C / min, and the stirring speed is 29 r / min.

[0069] 7) Disperse and classify precursor H, and select precursor H with a particle size D50 of 15 μm and D90 not exceeding 40 μm for graphitization to obtain material I; the graphitization temperature is 3200 °C, and the graphitization time is 30 h; the tertiary tail material formed during the dispersion and classification process is returned to step 1) for recycling.

[0070] 8) Mix 100 parts by mass of material I, 3 parts by mass of Ketjen black, and 7 parts by mass of binder B evenly in a mixer to obtain material K; binder B uses 50wt% modified pitch and 50wt% mesophase pitch.

[0071] 9) Carbonize material K in a tunnel kiln under a nitrogen atmosphere at a temperature of 1150 °C to obtain material L; the heating rate during the carbonization process in this step is 3.5 °C / min;

[0072] 10) Mix, screen, and demagnetize material L to obtain the anode material.

[0073] Comparative Example 1:

[0074] Based on Example 4, the precursor C obtained in step 1) was not subjected to step 2) pressure molding, step 3) semi-coking carbonization treatment, step 4) crushing, shaping, and step 5) secondary granulation. The precursor C obtained in step 1) was directly prepared into the anode material through steps 6) to 10). The processes used in the same steps were the same.

[0075] Comparative Example 2:

[0076] Based on Example 4, in step 1), the tailing A was replaced with acicular coke with a D50 of 8 μm to obtain the precursor. The obtained precursor was not subjected to step 2) pressure molding, step 3) semi-coking carbonization treatment, step 4) crushing, shaping, and step 5). The precursor C obtained in step 1) was directly prepared into the anode material through steps 6) to 10). Other processes used in the same steps were the same.

[0077] Performance Test:

[0078] Capacity Test: The anode materials prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were respectively mixed with a conductive agent and PVDF in a weight ratio of 93:3:4 to form a slurry, and then coated on a copper foil to prepare an anode sheet. After drying, it was used as the anode, and a lithium sheet was used as the positive electrode to assemble a lithium-ion battery for performance testing. The testing method was as follows: The anode material was subjected to electrical performance testing using a LANHE multi-channel battery testing system, etc. The charge and discharge voltage was 0.01 to 2.0 V, and the charge and discharge rate was 0.1 C. The first reversible capacity and the first Coulomb efficiency were obtained through testing.

[0079] Apparent Density Test: The above-mentioned mixed slurry was coated on a copper foil with a thickness of 100 μm to prepare an anode sheet. After drying, a size of 10 cm * 10 cm was cut, and the thickness D1 before rolling was measured (the average value of the thicknesses at three different points). It was rolled on a rolling press with a rolling pressure of 15 tons, and then the thickness D2 after rolling was tested (the average value of the thicknesses at three different points), and the mass of the electrode sheet was weighed as M1; at the same time, the weight of a 10 cm * 10 cm copper foil current collector was weighed as M2; the units of D1 and D2 were mm, and the units of M1 and M2 were g. The apparent density of the electrode sheet was calculated according to the formula PD = (M2 - M1) / {10 * 10 * (D2 - 21)} × 100.

[0080] Rate Performance Test: The anode materials prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were respectively made into anodes. Using lithium cobaltate as the cathode and 1 M-LiPF6 + EC:DEC:DMC (volume ratio 1:1:1) solution as the electrolyte, a full cell was assembled. It was charged to 4.2 V at a rate of 0.5 C, and then discharged to 2.6 V at rates of 1 C and 3 C respectively to test the capacity retention rate of the rate performance.

[0081] The performance of the lithium-ion battery negative electrode materials and the comparative products produced in the above Examples 1 to 4 were tested, and the test results are shown in the following table:

[0082] Project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Initial Reversible Capacity mAh / g 342.76 347.48 353.76 353.76 347.68 351.24 Initial Coulombic Efficiency % 92.7 92.8 93.4 93.8 91.8 93.2 <![CDATA[Compaction density g / cm 3 > 1.5 1.5 1.6 1.6 1.3 1.5 Rate Performance Capacity Retention 3C / 1C (%) 94.5 91.8 92.6 92.9 86.7 85.2

[0083] It can be seen from the test results that the technical solution provided by the present invention can make the negative electrode material prepared from the tailings meet the needs of the mainstream lithium-ion battery application market in terms of material specific capacity, compaction density, and rate performance, while the negative electrode material obtained by directly using the tailings to prepare the negative electrode material by granulation is low in compaction density, resulting in low energy density. Comparative Example 2 uses conventional raw materials to prepare the negative electrode material. In comparison, the rate performance of the negative electrode material prepared using the tailings is better. It can be seen that the technical solution provided by the present invention can achieve efficient utilization of various coke or graphite tailings generated in the process of producing graphite negative electrodes, is easy to realize industrialization, improves the utilization rate of raw materials, reduces production costs, and the product performance reaches or exceeds the performance of the negative electrode material prepared using conventional raw materials.

[0084] The technical solution provided by the present invention uses coke tails or graphite tails recovered in the process of producing graphite negative electrode materials to regenerate the tails into semi-coked materials through molding and low-temperature carbonization. After carbonization treatment and semi-coking, since the binder B is in a semi-coked state, the whole material retains 1wt% to 10wt% of volatile matter, the bonding force between the tails A and the binder B is enhanced, the bonding state of the materials is similar to that of the raw materials of coke, and various physical indicators are also very close. The semi-coked material E is not easily broken up into materials with smaller particle sizes during the grinding and shaping processes, but forms solid particles; at the same time, because the materials have been molded, they are densely filled, and the pores and cavities between the materials are filled with the binder, so that the tap density of the materials is greatly improved. After the semi-coked material E is crushed and shaped and mixed with the binder B, it is subjected to secondary granulation in a reactor to form a larger, isotropic particle. Lithium ions can enter the graphite interlayer from channels in all directions. Since the particle size of the formed particles is appropriate, the diffusion path of lithium ions is greatly reduced, and the prepared negative electrode material exhibits excellent rate performance. The conductive agent is added during the secondary coating process to enhance the conductivity of the negative electrode material, reduce the polarization of the battery, and increase the specific capacity.

[0085] The present invention is not limited to the above preferred embodiments, and can also be transformed and improved in various forms within the spirit defined in the claims and the specification of the present invention, which can solve the same technical problems and achieve the expected technical effects, so it will not be repeated. All solutions that can be directly or associatively derived from the contents disclosed by ordinary technicians in the field, as long as they are within the spirit defined in the claims, also belong to the protection scope of the present invention.

Claims

1. A production method for preparing the negative electrode material of a lithium-ion battery using tailings, characterized in that, it includes the following steps: 1) Mix 100 parts by mass of tailing A and 5 - 35 parts by mass of binder B evenly in a mixer to obtain precursor C; 2) Perform a shaping process on precursor C to obtain precursor D; 3) Carbonize precursor D under a nitrogen atmosphere at a temperature of 300 - 500 °C to obtain semi-coked material E; 4) Crush and shape semi-coked material E to obtain material F; the secondary tailings formed during the crushing and shaping process are returned to step 1) for recycling; 5) Mix 100 parts by mass of material F and 5 - 20 parts by mass of binder B evenly in a mixer to obtain precursor G; 6) Put precursor G into a reaction kettle and perform heat treatment under a nitrogen atmosphere to obtain precursor H; the heat treatment temperature is 550 - 700 °C, the heating rate of the reaction kettle is 2 - 10 °C / min, and the stirring speed is 15 - 40 r / min; 7) Disintegrate and classify precursor H, and select precursor H with a particle size D50 of 10 - 20 μm and D90 not exceeding 40 μm for graphitization to obtain material I; the graphitization temperature is 2800 - 3300 °C, and the graphitization time is 24 - 48 h; the tertiary tailings formed during the disintegration and classification process are returned to step 1) for recycling; 8) Mix 100 parts by mass of material I, 0.1 - 5 parts by mass of conductive agent J, and 1 - 10 parts by mass of binder B evenly in a mixer to obtain material K; the conductive agent J includes one or a mixture of two or more of carbon nanotubes, carbon black, acetylene black, and Ketjen black; 9) Carbonize material K under a nitrogen atmosphere at a temperature of 900 - 1300 °C to obtain material L; the heating rate during the carbonization process in this step is 1 - 5 °C / min; 10) Mix, screen, and demagnetize material L to obtain the negative electrode material; the tailing A is coke tailings or graphite tailings generated during the production of the graphite negative electrode material; the particle size D50 of the tailing A ≤ 5 μm; the binder B includes one or a mixture of two or more of medium-temperature pitch, high-temperature pitch, modified pitch, mesophase pitch, phenolic resin, and epoxy resin.

2. The production method for preparing the negative electrode material of a lithium-ion battery using tailings according to claim 1, characterized in that, the mixer includes a V-type high-efficiency mixer, a fusion machine, a twin-screw conical mixer, a conical high-speed mixer, a ribbon mixer, and a gravity-free mixer.

3. The production method for preparing the negative electrode material of a lithium-ion battery using tailings according to claim 1, characterized in that, the shaping process in step 2) includes isostatic pressing, molding, extrusion molding, and granulator molding, and the molding pressure is 20 - 200 MPa.

4. The production method for preparing the negative electrode material of a lithium-ion battery using tailings according to claim 1, characterized in that, the volatile content of the semi-coked material E prepared by carbonization in step 3) is 1 wt% - 10 wt%.

5. The production method for preparing the negative electrode material of a lithium-ion battery using tailings according to claim 1, characterized in that, The equipment used for carbonization treatment to prepare the semi-coked material E in step 3) includes a baking furnace, a carbonization furnace, a roasting furnace, a pusher furnace, a tunnel kiln, a shaft furnace, and an Acheson furnace.

6. The production method for preparing a lithium-ion battery anode material using tailings according to claim 1, characterized in that the equipment used for carbonization treatment in step 9) includes a high-temperature carbonization furnace, a pusher furnace, a roller hearth kiln, and a tunnel kiln.

7. The production method for preparing a lithium-ion battery anode material using tailings according to claim 1, characterized in that The particle size D of the material F 50 is 6 - 12 μm, and those with a particle size less than 2 μm and exceeding 25 μm do not exceed 10 wt% respectively.

8. The production method for preparing a lithium-ion battery anode material using tailings according to claim 1, characterized in that the tailings A include one or a mixture of two or more of petroleum coke tailings, needle coke tailings, pitch coke tailings, and natural graphite tailings.