CN108682787B - Lithium ion battery pole piece and preparation method thereof - Google Patents
Lithium ion battery pole piece and preparation method thereof Download PDFInfo
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- CN108682787B CN108682787B CN201810601004.3A CN201810601004A CN108682787B CN 108682787 B CN108682787 B CN 108682787B CN 201810601004 A CN201810601004 A CN 201810601004A CN 108682787 B CN108682787 B CN 108682787B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention relates to the technical field of lithium ion battery electrode materials, in particular to a lithium ion battery pole piece and a preparation method thereof, and the lithium ion battery pole piece comprises 70-80 parts of a positive electrode/negative electrode active material, 1-3 parts of a pore-forming agent, 2-3 parts of a conductive agent, 1-2 parts of an adhesive and 40-60 parts of a solvent. On one hand, the addition of the graphene and the carbon nano tube is beneficial to the activation of transition lithium iron phosphate, the lithium iron phosphate can prevent the graphene and the carbon nano tube from agglomerating, uniform and stable modified lithium iron phosphate can be obtained more easily, on the other hand, lithium-rich compounds can be formed in the discharging process of the lithium iron phosphate, the lithium-rich compounds have good ionic conductivity, and meanwhile, the lithium-rich compounds can modify the surface structure of the lithium phosphate, so that the electronic conductivity of the surface of the lithium phosphate is improved.
Description
The technical field is as follows:
the invention relates to the technical field of lithium ion battery electrode materials, in particular to a lithium ion battery pole piece and a preparation method thereof.
Background art:
the lithium battery is a primary battery using lithium metal or lithium alloy as a negative electrode material and using a non-aqueous electrolyte solution, unlike a lithium ion battery, which is a rechargeable battery, and a lithium ion polymer battery. The inventor of lithium batteries was edison. Because the chemical characteristics of lithium metal are very active, the requirements on the environment for processing, storing and using the lithium metal are very high. Therefore, lithium batteries have not been used for a long time. With the development of microelectronic technology at the end of the twentieth century, miniaturized devices are increasing, and high requirements are made on power supplies. The lithium battery has then entered a large-scale practical stage. Lithium iron phosphate system anode reaction: lithium ions are intercalated and deintercalated during discharge and charge. During charging: LiFePO4 → Li1-xFePO4+ xLi + + xe-when discharging: li1-xFePO4+ xLi + + xe- → LiFePO4 negative electrode, negative electrode material: graphite is mostly used. New studies found that titanate may be a better material. And (3) cathode reaction: lithium ions are deintercalated during discharge and are intercalated during charge. During charging: when xLi + + xe- +6C → LixC6 discharges: LixC6 → xLi + + xe- + 6C. The lithium iron phosphate battery has the characteristics of good safety, high energy density and the like, and is a mainstream battery in a power battery. However, in a low-temperature environment, resistance to lithium ion coming out of the positive electrode material and migrating in the electrolyte is increased, and the charge and discharge performance and the cycle performance of the lithium iron phosphate battery are sharply reduced, so that the improvement of the charge and discharge performance and the cycle performance of the lithium iron phosphate battery in the low-temperature environment is of great significance.
At present, the synthesis method of lithium iron phosphate materials is mainly divided into a solid phase method and a liquid phase method. The solid phase method mainly utilizes iron salt, lithium salt and phosphate to realize the synthesis of the lithium iron phosphate by high-temperature sintering. The liquid phase method is to dissolve soluble iron salt, lithium salt and phosphate in a solvent, prepare lithium iron phosphate or a precursor thereof by utilizing an ion reaction, and then prepare a finished product by high-temperature sintering. The solid phase method has simple reaction, easy processing of raw materials and high yield, but the morphology of the raw materials is not easy to control, and the tap density and the compacted density of the product are low. For example, the invention patents CN101200289, CN1762798, CN101140985 and the like all adopt a solid phase synthesis process route. Some new synthetic methods, such as microwave synthesis (CN101172597, CN101807692A) and ultrasonic coprecipitation (CN101800311A), can be classified into solid phase synthesis. The liquid phase method requires pretreatment by using a reaction kettle, and also requires processes such as drying and filtering, and the process is complex. But the product has generally better sphericity, higher tap density and excellent capacity and high rate performance. The invention patents CN101172599, CN101047242 and CN101121509 all adopt the process routes. The successful application of iron phosphate materials is that the surface is coated with a conductive carbon layer. Is actually a lithium iron phosphate/carbon composite material. Only the lithium iron phosphate material coated with carbon can normally exert the electrochemical performance. However, carbon added in the general process is loose in texture and is loosely distributed among lithium iron phosphate particles, so that the bulk density of the lithium iron phosphate material is seriously reduced. The cathode material is one of the key materials of the lithium ion battery, and the lithium ion battery cathode material which is commercially used at present is mainly a carbon cathode material. The lithium ion battery has the advantages of high specific capacity (200-400 mAh/g), low electrode potential (less than 1.0V vs Li +/Li), high cycle efficiency (more than 95%), long cycle life and the like. The carbon negative electrode material comprises mesocarbon microbeads (MCMB), graphite and amorphous carbon, wherein the graphite has good conductivity and high crystallinity and has a good layered structure, the reversible specific capacity can reach more than 300mah/g, Chen and other people have invented a superfine graphite negative electrode material, auxiliary materials after high-end graphite production are adopted as main raw materials of the product, the granularity is reduced to 5um by fine crushing, the reference is the standard, surface treatment is carried out, 3000-degree graphitization sintering is carried out after 1200-degree carbonization, corresponding products are obtained by coarse crushing and sieving, and the product has good conductive effect, low resistance, good processing performance in the production process of lithium ion batteries, stable performance and high cost performance, and is the optimal negative electrode material of a multiplying power lithium battery. But the disadvantages are that the graphite material has poor structural stability and poor compatibility with electrolyte, and the diffusion speed of Li ions in the ordered layered structure is slow, so that the material cannot be charged and discharged at a large multiplying power. The soft carbon has low crystallinity, small crystal grain size, large crystal face spacing and good compatibility with electrolyte, but has good charge-discharge irreversible capacity for the first time and small application range, and the artificial graphite has certain structural defects of the lithium ion battery cathode material itself, and needs to be subjected to further surface modification and modification in order to obtain the cathode material with high electrochemical performance.
The invention content is as follows:
the invention overcomes the defects of the prior art and provides a lithium ion battery pole piece and a preparation method thereof.
The technical problem to be solved by the invention is realized by adopting the following technical scheme: a preparation method of a lithium ion battery pole piece comprises, by weight, 70-80 parts of positive/negative active materials, 1-3 parts of pore-forming agents, 2-3 parts of conductive agents, 1-2 parts of adhesives and 40-60 parts of solvents;
and preparing the lithium ion battery pole piece by the following steps:
(1) preparing a positive electrode active material and a negative electrode active material;
(2) mixing the anode/cathode active material in the step (1) with a pore-forming agent, a conductive agent, an adhesive and a solvent respectively, and preparing to form slurry A and slurry B;
(3) and (3) coating the slurry A, B obtained in the step (2) on a current collector, drying at 50-55 ℃, 65-75 ℃, 80-85 ℃ and 75-80 ℃, rolling, and slitting to obtain the lithium ion battery pole piece.
Preferably, in this application, the pore-forming agent is polystyrene ball, the particle size of the pore-forming agent is less than or equal to 2.0um, the conductive agent is acetylene black, and the solvent is absolute ethyl alcohol.
Preferably, in the present application, the positive electrode active material is prepared by:
(1) mixing the following components in a mass ratio of 2: 1, putting graphene and carbon nanotubes into ethanol, carrying out ultrasonic primary crushing treatment, mixing and stirring for 4-6 minutes at normal temperature, heating to 40-60 ℃ at a speed of 2-4 ℃/min in an inert gas protection environment, preserving heat for 4-6 hours, and naturally cooling to room temperature to obtain a mixed solution;
the graphene is multilayer graphene, the interior of the multilayer graphene is of a three-dimensional conductive network structure, the carbon nano tubes are inserted in the three-dimensional conductive network, and the particle size of particles formed after the multilayer graphene and the carbon nano tubes are reacted is 700 nm-22 um;
(2) crushing lithium iron phosphate to a particle size of 3-6 um, and putting the lithium iron phosphate into a stirring kettle, wherein the mass ratio of the lithium iron phosphate to distilled water is 1: 2-7, slowly adding distilled water, adding a coupling agent and acetylene black, quickly stirring for 10-16 min, adding the mixed solution obtained in the step (1) into a stirring kettle, and uniformly stirring to obtain a modified intermediate;
(3) adding the modified intermediate prepared in the step (2) into an atomizer for spray drying treatment, wherein in the process, a gaseous carbon source is blown in under the action of protective gas, so that the gaseous carbon source is cracked on the surface of the modified intermediate to form amorphous carbon, and the amorphous carbon is coated on the surface of the modified intermediate to form a uniform coating layer;
(4) and (4) drying the powder particles obtained in the step (3) in vacuum, and calcining for 3-4 hours at 250-350 ℃ under the action of protective gas to obtain the modified lithium iron phosphate anode material.
Preferably, in the present application, the coupling agent is gamma-mercaptopropyltrimethoxysilane, methyl isobutyl ketoximosilane or vinyltriethoxysilane, and the coupling agent: acetylene black: the mass ratio of the mixed solution is as follows: (0.1-2: 1-1.6: 100);
and (3) putting the modified intermediate into an atomizer, heating to 500-700 ℃ under the protection of nitrogen for annealing, loading 24-26% of gaseous carbon source into protective gas at the gas flow rate of 50-1000 ml/min, starting the atomizer, carrying the atomized fine components in the atomizer into a high-temperature furnace by the protective gas, preserving the temperature for 1-12 hours, cracking the gaseous carbon source on the surface of the modified intermediate to form amorphous carbon, and coating the amorphous carbon on the surface of the modified intermediate to form a uniform coating layer with the thickness of 0.3-30 nm.
Preferably, in the present application, the negative electrode active material is prepared by:
(1) mixing the following components in a mass ratio of 2: 1, putting graphene and carbon nanotubes into absolute ethyl alcohol, carrying out ultrasonic primary crushing treatment, mixing and stirring for 4-6 minutes at normal temperature, heating to 40-60 ℃ at a speed of 2-4 ℃/min in an inert gas protection environment, preserving heat for 4-6 hours, and naturally cooling to room temperature to obtain a mixed solution;
the graphene is multilayer graphene, the interior of the multilayer graphene is of a three-dimensional conductive network structure, the carbon nano tubes are inserted in the three-dimensional conductive network, and the particle size of particles formed after the multilayer graphene and the carbon nano tubes are acted is 600 nm-20 um.
(2) The method comprises the following steps of (1) adopting petroleum asphalt as a base material, crushing and ball-milling the base material until the particle size is 120-140 um, and then putting the treated particles into a reaction kettle for modification treatment, wherein the method comprises the following steps:
(2.1) introducing nitrogen at the air speed of 80-120 per hour, heating to 300-420 ℃, keeping the temperature at 40-60 ℃/h, and keeping the temperature for 2-6 h;
(2.2) taking part of the asphalt in the step (2.1) to be crushed until the particle size is below 20 mu m, measuring the softening point, and preserving the heat for 4-6 h at the temperature until the measured softening point is 180-380 ℃ of the asphalt base material;
(2.3) naturally cooling the asphalt base material in the step (2.2) to room temperature, and then crushing the asphalt base material to obtain the modified asphalt base material with the particle size of 18-20 um;
(3) dissolving the asphalt screen base material obtained in the step (2) in tetrahydrofuran to obtain a tetrahydrofuran solution of asphalt, pouring the prepared tetrahydrofuran solution of asphalt into the mixed solution, stirring for 20-40 min to obtain mixed slurry, and then adding a solvent to adjust the solid mass percentage content of the mixed slurry to 10-20%;
(4) and (4) drying the mixed slurry obtained in the step (3) through a closed circulation spray dryer, wherein the inlet temperature and the outlet temperature of the closed circulation spray dryer are respectively 120-140 ℃ and 70-60 ℃, and the rotating speed of an atomizer of the closed circulation spray dryer is 24000-26000 r/min, so as to obtain the lithium battery negative electrode active material.
Preferably, in the present application, the ratio of the parts by weight of the graphene and the carbon nanotube to the parts by weight of the absolute ethyl alcohol in the step (1) is 1: 1-1: 5.
a lithium ion battery pole piece is prepared by the preparation method of the lithium ion battery pole piece.
Compared with the prior art, the invention has the beneficial effects that:
1. in the application, when the positive active material is prepared, the carbon nano tube and the graphene are used as the modification additive, so that a structure that the lithium iron phosphate positive material is coated with amorphous carbon is formed. On one hand, the addition of the graphene and the carbon nano tube is beneficial to the activation of transition lithium iron phosphate, and the lithium iron phosphate can prevent the graphene and the carbon nano tube from agglomerating, so that uniform and stable modified lithium iron phosphate can be obtained more easily;
2. in this application, when preparing anodal active material, the coating is even fine and close amorphous carbon, and this amorphous carbon cladding is on the surface of modified intermediate and forms even coating, and its thickness is 0.3nm ~30nm, and this makes it except possessing the advantage of traditional coating, and the ultra-thin coating of nanometer level thickness still is favorable to reducing the migration path of lithium ion in the coating, further improves the multiplying power performance of material, makes it have good lithium ion conduction characteristic.
3. In the present application, when preparing the positive/negative active material, the high conductivity of graphene and carbon nanotubes is utilized, the graphene is multilayer graphene, the interior of the multilayer graphene is of a three-dimensional conductive network structure, further improving the migration speed of lithium electrons in the coating layer, inserting the carbon nano-tubes into the three-dimensional conductive network, wherein the particle diameter of particles formed by the action of the multilayer graphene and the carbon nano-tubes is 700 nm-22 um, the process comprises the steps of mixing and stirring for 4-6 minutes at normal temperature, then heating to 40-60 ℃ at the speed of 2-4 ℃/min in the environment protected by inert gas, then preserving heat for 4-6 hours, then naturally cooling to room temperature to obtain a mixed solution, so that micro bubbles between the multilayer graphene and the carbon nano-tube can be further removed to form a stable bonding layer, and the conductive characteristics of the graphene and the carbon nano-tube can be better exerted;
4. according to the process provided by the application, the graphene and the carbon nano tubes are completely distributed on the surface of the lithium iron phosphate material, so that a surface carbon layer with extremely high conductivity is formed, a loose and large carbon layer cannot be generated, the stacking density and the compaction density of the lithium iron phosphate anode material are effectively increased, and the reduction of the polarization resistance of lithium ions in the processes of releasing and embedding lithium ions on the surface of the anode material is facilitated;
5. when the negative active material is prepared, firstly, the carbon nano-tubes and the graphene are modified, the high conductivity of the graphene and the carbon nano-tubes is utilized, the graphene is multilayer graphene, the interior of the multilayer graphene is of a three-dimensional conductive network structure, the migration speed of lithium electrons in a coating layer is further improved, the carbon nano-tubes are inserted into the three-dimensional conductive network, the particle size of particles formed after the multilayer graphene and the carbon nano-tubes are acted is 700 nm-22 um, the process is that the particles are mixed and stirred for 4-6 minutes at normal temperature, then the temperature is increased to 40-60 ℃ at the speed of 2-4 ℃/min under the environment protected by inert gas, then the temperature is kept for 4-6 hours, and then the mixed solution is naturally cooled to room temperature, so that micro bubbles between the multilayer graphene and the carbon nano-tubes can be further removed, a stable binding layer is formed, and the conductive properties of the graphene and the carbon nano-tubes can be better exerted, and then, a precursor is prepared by using a closed cycle spray drying mode, modified asphalt is uniformly dispersed on the surface of graphene, after high-temperature heat treatment, the asphalt is carbonized to form a layer of amorphous carbon which tightly wraps the surface of the graphene to form a composite material with a 'core-shell' structure, the existence of a coating layer not only reduces the specific surface area of the material and prevents an organic solvent from entering, and the purpose of obtaining a uniform and compact SEI film is achieved, but also the surface carbon material can fix a graphite flake and prevent the surface layer of the graphite from falling off, so that the first efficiency, specific capacity and cycle stability of the material are improved to a certain extent.
6. In the application, the added pore-forming agent is heated and decomposed into gas in the segmented drying process, the gas overflows from the slurry to generate a large amount of pores in the slurry, uniform pores are left after drying, and the lithium ion battery electrode obtained after drying is rolled, so that not only is the compaction density unaffected, but also the pores in the lithium ion battery electrode are uniform respectively, and the porosity is higher than that of a common electrode.
The specific implementation mode is as follows:
in order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.
Example 1
A preparation method of a lithium ion battery pole piece comprises 75kg of positive/negative active material, 2kg of pore-forming agent, 2.5kg of conductive agent, 1.5kg of adhesive and 50kg of solvent;
and preparing the lithium ion battery pole piece by the following steps:
(1) preparing a positive electrode active material and a negative electrode active material;
(2) mixing the anode/cathode active material in the step (1) with a pore-forming agent, a conductive agent, an adhesive and a solvent respectively, and preparing to form slurry A and slurry B;
(3) and (3) coating the slurry A, B obtained in the step (2) on a current collector, drying at 50-55 ℃, 65-75 ℃, 80-85 ℃ and 75-80 ℃, rolling, and slitting to obtain the lithium ion battery pole piece.
In this embodiment, the pore-forming agent is a polystyrene sphere, the particle size of the pore-forming agent is not greater than 2.0um, the conductive agent is acetylene black, and the solvent is absolute ethyl alcohol.
In this example, the positive electrode active material was prepared by the following steps:
(1) mixing the following components in a mass ratio of 2: 1, putting graphene and carbon nanotubes into ethanol, carrying out ultrasonic primary crushing treatment, mixing and stirring for 4-6 minutes at normal temperature, heating to 40-60 ℃ at a speed of 2-4 ℃/min in an inert gas protection environment, preserving heat for 4-6 hours, and naturally cooling to room temperature to obtain a mixed solution;
the graphene is multilayer graphene, the interior of the multilayer graphene is of a three-dimensional conductive network structure, the carbon nano tubes are inserted in the three-dimensional conductive network, and the particle size of particles formed after the multilayer graphene and the carbon nano tubes are reacted is 700 nm-22 um;
(2) crushing lithium iron phosphate to a particle size of 3-6 um, and putting the lithium iron phosphate into a stirring kettle, wherein the mass ratio of the lithium iron phosphate to distilled water is 1: 2-7, slowly adding distilled water, adding a coupling agent and acetylene black, quickly stirring for 10-16 min, adding the mixed solution obtained in the step (1) into a stirring kettle, and uniformly stirring to obtain a modified intermediate;
(3) adding the modified intermediate prepared in the step (2) into an atomizer for spray drying treatment, wherein in the process, a gaseous carbon source is blown in under the action of protective gas, so that the gaseous carbon source is cracked on the surface of the modified intermediate to form amorphous carbon, and the amorphous carbon is coated on the surface of the modified intermediate to form a uniform coating layer;
(4) and (4) drying the powder particles obtained in the step (3) in vacuum, and calcining for 3-4 hours at 250-350 ℃ under the action of protective gas to obtain the modified lithium iron phosphate anode material.
In this embodiment, the coupling agent is γ -mercaptopropyl trimethoxysilane, methyl isobutyl ketoxime silane, or vinyl triethoxysilane, and the coupling agent: acetylene black: the mass ratio of the mixed solution is as follows: (0.1-2: 1-1.6: 100);
and (3) putting the modified intermediate into an atomizer, heating to 500-700 ℃ under the protection of nitrogen for annealing, loading 24-26% of gaseous carbon source into protective gas at the gas flow rate of 50-1000 ml/min, starting the atomizer, carrying the atomized fine components in the atomizer into a high-temperature furnace by the protective gas, preserving the temperature for 1-12 hours, cracking the gaseous carbon source on the surface of the modified intermediate to form amorphous carbon, and coating the amorphous carbon on the surface of the modified intermediate to form a uniform coating layer with the thickness of 0.3-30 nm.
In this example, the negative electrode active material was prepared by the following steps:
(1) mixing the following components in a mass ratio of 2: 1, putting graphene and carbon nanotubes into absolute ethyl alcohol, carrying out ultrasonic primary crushing treatment, mixing and stirring for 4-6 minutes at normal temperature, heating to 40-60 ℃ at a speed of 2-4 ℃/min in an inert gas protection environment, preserving heat for 4-6 hours, and naturally cooling to room temperature to obtain a mixed solution;
the graphene is multilayer graphene, the interior of the multilayer graphene is of a three-dimensional conductive network structure, the carbon nano tubes are inserted in the three-dimensional conductive network, and the particle size of particles formed after the multilayer graphene and the carbon nano tubes are acted is 600 nm-20 um.
(2) The method comprises the following steps of (1) adopting petroleum asphalt as a base material, crushing and ball-milling the base material until the particle size is 120-140 um, and then putting the treated particles into a reaction kettle for modification treatment, wherein the method comprises the following steps:
(2.1) introducing nitrogen at the air speed of 80-120 per hour, heating to 300-420 ℃, keeping the temperature at 40-60 ℃/h, and keeping the temperature for 2-6 h;
(2.2) taking part of the asphalt in the step (2.1) to be crushed until the particle size is below 20 mu m, measuring the softening point, and preserving the heat for 4-6 h at the temperature until the measured softening point is 180-380 ℃ of the asphalt base material;
(2.3) naturally cooling the asphalt base material in the step (2.2) to room temperature, and then crushing the asphalt base material to obtain the modified asphalt base material with the particle size of 18-20 um;
(3) dissolving the asphalt screen base material obtained in the step (2) in tetrahydrofuran to obtain a tetrahydrofuran solution of asphalt, pouring the prepared tetrahydrofuran solution of asphalt into the mixed solution, stirring for 20-40 min to obtain mixed slurry, and then adding a solvent to adjust the solid mass percentage content of the mixed slurry to 10-20%;
(4) and (4) drying the mixed slurry obtained in the step (3) through a closed circulation spray dryer, wherein the inlet temperature and the outlet temperature of the closed circulation spray dryer are respectively 120-140 ℃ and 70-60 ℃, and the rotating speed of an atomizer of the closed circulation spray dryer is 24000-26000 r/min, so as to obtain the lithium battery negative electrode active material.
The ratio of the weight parts of the graphene and the carbon nano tube to the weight parts of the absolute ethyl alcohol in the step (1) is 1: 1-1: 5.
a lithium ion battery pole piece is prepared by the preparation method of the lithium ion battery pole piece.
Example 2:
the content of the present embodiment is substantially the same as that of embodiment 1, and the same points are not repeated, except that: the cathode/anode active material composite material comprises 70kg of cathode/anode active material, 1kg of pore-forming agent, 2kg of conductive agent, 1kg of adhesive and 40kg of solvent.
Example 3:
the content of the present embodiment is substantially the same as that of embodiment 1, and the same points are not repeated, except that: the cathode/anode active material composite material comprises 80kg of cathode/anode active material, 3kg of pore-forming agent, 3kg of conductive agent, 2kg of adhesive and 60kg of solvent.
Comparative example 1:
the electrode piece prepared and formed by the application number CN201210380360.X and the lithium ion battery thereof are adopted for testing in the comparative example.
Battery performance testing
Under the same conditions of compacted density, the porosity of the electrode was measured by using a mercury porosimeter, the electrolyte was dropped into a dry glove box to measure the liquid permeation time, and the lithium ion batteries prepared in examples 1 to 3 and comparative example 1 were subjected to battery cycle and self-discharge tests, and the results are shown in the following table 1:
TABLE 1 comparison of physical and electrochemical Properties of the electrodes
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (5)
1. A preparation method of a lithium ion battery pole piece is characterized by comprising 70-80 parts of positive/negative active material, 1-3 parts of pore-forming agent, 2-3 parts of conductive agent, 1-2 parts of adhesive and 40-60 parts of solvent by weight;
and preparing the lithium ion battery pole piece by the following steps:
(1) preparing a positive electrode active material and a negative electrode active material;
(2) mixing the anode/cathode active material in the step (1) with a pore-forming agent, a conductive agent, an adhesive and a solvent respectively, and preparing to form slurry A and slurry B;
(3) coating the slurry A, B in the step (2) on a current collector, drying at 50-55 ℃, 65-75 ℃, 80-85 ℃ and 75-80 ℃, rolling, and slitting to obtain the lithium ion battery pole piece;
the negative active material is prepared by the following steps:
(1) mixing the following components in a mass ratio of 2: 1, putting graphene and carbon nanotubes into absolute ethyl alcohol, carrying out ultrasonic primary crushing treatment, mixing and stirring for 4-6 minutes at normal temperature, heating to 40-60 ℃ at a speed of 2-4 ℃/min in an inert gas protection environment, preserving heat for 4-6 hours, and naturally cooling to room temperature to obtain a mixed solution;
the graphene is multilayer graphene, the interior of the multilayer graphene is of a three-dimensional conductive network structure, the carbon nano tubes are inserted in the three-dimensional conductive network, and the particle size of particles formed after the multilayer graphene and the carbon nano tubes are reacted is 600 nm-20 mu m;
(2) the method comprises the following steps of (1) taking petroleum asphalt as a base material, crushing and ball-milling the base material until the particle size is 120-140 mu m, and then putting the treated particles into a reaction kettle for modification treatment, wherein the method comprises the following steps:
(2.1) introducing nitrogen at the air speed of 80-120 per hour, heating to 300-420 ℃, keeping the temperature at 40-60 ℃/h, and keeping the temperature for 2-6 h;
(2.2) taking part of the asphalt in the step (2.1) to be crushed to the particle size of below 20 mu m, measuring the softening point, and preserving the heat for 4-6 h at the temperature until the measured softening point is the asphalt base stock at 180-380 ℃;
(2.3) naturally cooling the asphalt base material in the step (2.2) to room temperature, and then crushing the asphalt base material to obtain the modified asphalt base material with the particle size of 18-20 microns;
(3) dissolving the modified asphalt base material obtained in the step (2) in tetrahydrofuran to obtain a tetrahydrofuran solution of asphalt, pouring the prepared tetrahydrofuran solution of asphalt into the mixed solution, stirring for 20-40 min to obtain mixed slurry, and then adding a solvent to adjust the solid mass percentage content of the mixed slurry to 10-20%;
(4) drying the mixed slurry obtained in the step (3) through a closed circulation spray dryer, wherein the inlet temperature and the outlet temperature of the closed circulation spray dryer are respectively 120-140 ℃ and 70-60 ℃, and the rotating speed of an atomizer of the closed circulation spray dryer is 24000-26000 r/min, so as to obtain the lithium battery negative electrode active material;
the ratio of the weight parts of the graphene and the carbon nano tube to the weight parts of the absolute ethyl alcohol in the step (1) is 1: 1-1: 5.
2. the preparation method of the lithium ion battery pole piece according to claim 1, wherein the pore-forming agent is polystyrene spheres, the particle size of the pore-forming agent is less than or equal to 2.0 μm, the conductive agent is acetylene black, and the solvent is absolute ethyl alcohol.
3. The method for preparing the lithium ion battery pole piece according to claim 1, wherein the positive active material is prepared by the following steps:
(1) mixing the following components in a mass ratio of 2: 1, putting graphene and carbon nanotubes into ethanol, carrying out ultrasonic primary crushing treatment, mixing and stirring for 4-6 minutes at normal temperature, heating to 40-60 ℃ at a speed of 2-4 ℃/min in an inert gas protection environment, preserving heat for 4-6 hours, and naturally cooling to room temperature to obtain a mixed solution;
the graphene is multilayer graphene, the interior of the multilayer graphene is of a three-dimensional conductive network structure, the carbon nano tubes are inserted in the three-dimensional conductive network, and the particle size of particles formed after the multilayer graphene and the carbon nano tubes are reacted is 700 nm-22 mu m;
(2) crushing lithium iron phosphate to a particle size of 3-6 mu m, and adding the lithium iron phosphate into a stirring kettle, wherein the mass ratio of the lithium iron phosphate to distilled water is = 1: 2-7, slowly adding distilled water, adding a coupling agent and acetylene black, quickly stirring for 10-16 min, adding the mixed solution obtained in the step (1) into a stirring kettle, and uniformly stirring to obtain a modified intermediate;
(3) adding the modified intermediate prepared in the step (2) into an atomizer for spray drying treatment, wherein in the process, a gaseous carbon source is blown in under the action of protective gas, so that the gaseous carbon source is cracked on the surface of the modified intermediate to form amorphous carbon, and the amorphous carbon is coated on the surface of the modified intermediate to form a uniform coating layer;
(4) and (4) drying the powder particles obtained in the step (3) in vacuum, and calcining for 3-4 hours at 250-350 ℃ under the action of protective gas to obtain the modified lithium iron phosphate anode material.
4. The preparation method of the lithium ion battery pole piece according to claim 3, wherein the coupling agent is gamma-mercaptopropyltrimethoxysilane, methyl isobutyl ketoximosilane or vinyl triethoxysilane, and the coupling agent: acetylene black: the mass ratio of the mixed solution is as follows: (0.1-2: 1-1.6: 100);
and (3) putting the modified intermediate into an atomizer, heating to 500-700 ℃ under the protection of nitrogen for annealing, loading 24-26% of gaseous carbon source into protective gas at the gas flow rate of 50-1000 ml/min, starting the atomizer, carrying the atomized fine components in the atomizer into a high-temperature furnace by the protective gas, preserving the temperature for 1-12 hours, cracking the gaseous carbon source on the surface of the modified intermediate to form amorphous carbon, and coating the amorphous carbon on the surface of the modified intermediate to form a uniform coating with the thickness of 0.3-30 nm.
5. A lithium ion battery pole piece is characterized in that the lithium ion battery pole piece is prepared by the preparation method of the lithium ion battery pole piece according to any one of claims 1 to 4.
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| CN109698338A (en) * | 2018-12-26 | 2019-04-30 | 湖北锂诺新能源科技有限公司 | A kind of powerful graphene-based LiFePO4 pole piece of low cost and preparation method |
| CN111554898B (en) * | 2020-05-11 | 2022-02-11 | 珠海冠宇电池股份有限公司 | Negative electrode material and preparation method and application thereof |
| CN111653831B (en) * | 2020-06-22 | 2022-03-25 | 天能帅福得能源股份有限公司 | Preparation method of high-safety, high-temperature and long-life water-based lithium iron phosphate battery |
| CN114899369B (en) * | 2022-04-08 | 2024-03-12 | 西部诚业科技发展(深圳)有限公司 | Conductive composition and preparation method thereof |
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