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CN116173828B - A processing method for electrode material and a processing method for electrode pole piece - Google Patents

A processing method for electrode material and a processing method for electrode pole piece Download PDF

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Publication number
CN116173828B
CN116173828B CN202310152550.4A CN202310152550A CN116173828B CN 116173828 B CN116173828 B CN 116173828B CN 202310152550 A CN202310152550 A CN 202310152550A CN 116173828 B CN116173828 B CN 116173828B
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electrode
cooling water
electrode material
powder
stirring
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CN116173828A (en
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张鑫天
卢军太
魏建良
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Jiangsu Zenio New Energy Battery Technologies Co Ltd
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Jiangsu Zenio New Energy Battery Technologies Co Ltd
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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
    • H01M4/04—Processes of manufacture in general
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H01M4/0435—Rolling or calendering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
    • B01J2/10—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic in stationary drums or troughs, provided with kneading or mixing appliances
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D7/00—Producing flat articles, e.g. films or sheets
    • B29D7/01—Films or sheets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
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    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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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    • 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
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • H01M4/621—Binders
    • 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
    • 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

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  • Manufacturing & Machinery (AREA)
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  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention discloses a processing method of an electrode material and a processing method of an electrode plate, and belongs to the technical field of lithium ion battery materials. In the processing process of the electrode material, the granulator is used for stirring the mixed material, the loose density change of the material in the stirring process is monitored, the mixing uniformity degree of the material can be regulated and controlled, meanwhile, the heat generated by the granulator in the high-speed stirring process is used for regulating and controlling the fiberization degree of the binder, meanwhile, the electrode material prepared by the granulator has good mixing effect and uniform particle size, when the powder is calendered to form a film, the thickness of the prepared film is uniform, the consistency is good, the problems of holes or uneven edges on the electrode film are solved, and the secondary battery prepared by the method is improved in manufacturing rate and electrochemical performance.

Description

Electrode material processing method and electrode plate processing method
Technical Field
The invention relates to the technical field of lithium ion battery materials, in particular to a processing method of an electrode material and a processing method of an electrode plate.
Background
In recent years, with the rapid increase of application of lithium ion batteries in fields of electric automobiles, energy storage, 3C and the like, the overall yield and market scale of the global lithium ion batteries are rapidly improved, but are influenced by epidemic situations, rising prices of partial raw materials and other factors, and the cost reduction measures in the industry mainly comprise the aspects of selecting low-cost materials, developing new processes, improving the qualification rate of products and the like. For example, the selection of electrode materials, separator films and electrolytes, which are relatively low in cost, can result in poor battery safety. For example, the coating surface density is increased to reduce the cost of the battery, but the problems of coating leakage and incapability of drying in an oven exist in the coating process, so that the coating surface density cannot be infinitely increased, and the coating surface density is limited. In addition, the dry electrode plate is prepared by adopting a dry process, the processes of coating and baking the electrode plate are reduced in the preparation process, the use of toxic solvent NMP is omitted, the raw materials are stirred, dispersed and calendered into a film, and then the film and the current collector are compounded to obtain the electrode plate.
CN112687833a discloses a preparation method of a dry electrode slice, the preparation method of the dry electrode slice comprises the steps of mixing raw material powder, heating and fiberizing to obtain pole slice powder, sequentially vertically rolling and horizontally rolling the pole slice powder to obtain a membrane, and feeding the membrane and foil into a laminating roller together, and rolling and forming to obtain the electrode slice. CN114583111a discloses a preparation method of a dry electrode with continuous discharging, which comprises the following steps of feeding a positive electrode material or a negative electrode material into a powder metering tank, mixing by a mixing barrel, stirring and shearing at high temperature by four cavities, conveying and discharging by three cavities, crushing the agglomeration part inside the powder metering tank by an ultrasonic vibrating screen, pressing and rolling, and cutting. CN114171710a discloses an in-situ preparation method of a dry electrode film, which comprises the steps of premixing active material dry powder, polymer binder dry powder and conductive agent dry powder under the condition that the dew point is-25-65 ℃, placing the premixed active material dry powder, the polymer binder dry powder and the conductive agent dry powder in a double-screw extruder, heating the mixture through radiation, carrying out in-situ crosslinking reaction, and extruding to form the dry electrode film, wherein the binder is a binder with a low melting point of 50-120 ℃.
In the above-mentioned dry electrode sheet preparation method, the raw material powder is mixed and heated to be fibrillated, and the mixture is stirred and sheared at high temperature, and the mixture is subjected to in-situ crosslinking reaction by radiation heating in a twin-screw extruder. The preparation process is relatively complex, the operation is difficult, the preparation period is long, the heating energy consumption is high, and the like, so that the preparation cost is high.
In view of this, it is necessary to provide a method for processing an electrode material and a method for processing an electrode sheet.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a processing method of an electrode material and a processing method of an electrode plate.
The invention solves the technical problems by adopting the following technical scheme.
The embodiment of the invention provides a processing method of an electrode material, which comprises the following steps:
Adding an electrode active material and a conductive agent into a granulator, adopting medium-speed stirring at 1000-2000rpm for 5-15min to obtain a uniform mixed material, and testing the apparent density of the mixed material to be BD 0;
adding a binder into the mixed material, and stirring at a high speed of 5000-7000rpm for 3-10min to obtain a fiberized material, wherein the fiberized material has a bulk density BD t when the test stirring time is t, BD t＜BD0 and BD t/BD0 <50%;
And thirdly, scattering the fiberized material at a low speed of 100-500rpm, wherein the low-speed stirring time is 5-10min, and thus the electrode material with uniform particles is obtained.
The invention provides a processing method of an electrode plate, which comprises the steps of calendaring an electrode material into a dry-method membrane, winding and unwinding the dry-method membrane, and attaching the dry-method membrane to two sides of a current collector through flat hot pressing to obtain the dry-method electrode plate, wherein the electrode material is processed according to the processing method.
The invention provides a lithium ion battery, which comprises the electrode plate.
The invention has the following beneficial effects:
according to the processing method of the electrode material and the processing method of the electrode pole piece, provided by the invention, the mixing, the fiberization and the scattering of materials can be realized in the granulator by controlling the stirring speed of the granulator, the mixing uniformity degree of the materials can be regulated and controlled by monitoring the loose density change of the materials during the fiberization of the materials, so that the electrode material with good mixing effect and uniform particle size is prepared, and the prepared membrane has uniform thickness and good consistency when the electrode material is calendered to form a film, so that the problems of holes, uneven edges and the like on the electrode membrane are solved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a dry electrode powder fiberizing process;
FIG. 2 is a schematic view of a pelletizer;
FIG. 3 is a graph showing the apparent bulk density of the powder in example 1 with stirring time;
FIG. 4 is a photograph of the powder after high-speed stirring in example 1;
FIG. 5 is a photograph of the powder material of example 1 after low-speed scattering;
Fig. 6 is an SEM image of the pole piece prepared in example 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
The dry electrode powder fibrosis processing method provided by the embodiment of the invention is used for solving the defects that in the prior art, the mixing uniformity of powder cannot be monitored, the powder is subjected to an additional heating process, uneven discharging is caused by uneven particle size of the powder, the prepared electrode plate is poor in uniformity, holes, broken belts or uneven edges occur, the preparation process is complex, the operation is difficult, the heating energy consumption is high and the like.
The method for processing the electrode material and the method for processing the electrode plate provided by the embodiment of the invention are specifically described below.
In a first aspect, an embodiment of the present invention provides a method for processing an electrode material, including the steps of:
Adding an electrode active material and a conductive agent into a granulator, adopting medium-speed stirring at 1000-2000rpm for 5-15min, controlling the temperature of powder to be 25-50 ℃ to obtain a uniform mixed material, and testing the apparent density of the mixed material to be BD 0;
Adding a binder into the mixed material, stirring at a high speed of 5000-7000rpm for 3-10min, controlling the temperature of powder to be 70-160 ℃ to obtain a fiberized material, and requiring the loose density BD t of the fiberized material when the test stirring time is t, wherein BD t＜BD0 is 20% < BD t/BD0 <50%;
And thirdly, scattering the fiberized material at a low speed of 100-500rpm, wherein the low-speed stirring time is 5-10min, and the temperature of the powder is controlled at 25-35 ℃ to obtain the electrode material with uniform particles, wherein the particle size of the electrode material is 0.2-5mm.
According to the processing method of the electrode material, through controlling the stirring speed of the granulator, material mixing, material fiberization and material scattering can be realized in the granulator, and the loose density change of the material can be monitored during material fiberization, so that the material mixing uniformity degree can be regulated and controlled, and further, the electrode material with good mixing effect and uniform particle size can be prepared, a membrane with good apparent performance can be manufactured by adopting the electrode material prepared by the method, and further, a lithium battery with good battery performance can be manufactured by adopting the membrane.
In an alternative embodiment, the loose density testing method is a Scott volumetric method or a vibration hopper method, which are all existing and mature testing methods, and are suitable for the use site of the granulator, so that the loose density change of the fiberized material can be monitored conveniently, and of course, the loose density testing method can be other testing methods with the same or similar functions.
In particular, regarding the bulk density BD t of the fiberized material at a stirring time t, the BD t may be one or more, for example, the fiberized material at a stirring time of 3 minutes may be taken and tested for bulk density, and for example, the fiberized material may be taken and tested at intervals of 1 minute, 2 minutes, 3 minutes, or 5 minutes, and the total number of tests during mixing may be 2,4, 6, 8, or 10, etc. Through testing and obtaining a plurality of BD t, a change curve (shown in fig. 3) of loose density along with stirring time can be obtained through fitting and the like, and the material fibrosis degree and the proper stirring time under different time can be obtained through the curve, so that a follow-up worker can conveniently check the material fibrosis degree and the stirring time.
In an alternative embodiment, the mass ratio of the electrode active material, the conductive agent, and the binder is 80-98:1-5:1-10;
The binder is a fiberizable binder and comprises at least one of polyvinylidene fluoride, acrylic resin, polytetrafluoroethylene and styrene-butadiene rubber;
the conductive agent comprises at least one of acetylene black, conductive carbon black, ketjen black, graphene, carbon nanotubes and carbon fibers, and the bulk density of the conductive agent is 0.05-0.2g/cm 3;
The electrode active material is a positive electrode material or a negative electrode material, the positive electrode material comprises at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobaltate, lithium titanate and lithium nickel cobalt manganate, the apparent density of the positive electrode material is 1.0-2.0g/cm 3, the negative electrode material comprises at least one of graphite, silicon oxide, hard carbon and soft carbon, and the apparent density of the negative electrode material is 0.5-1.5g/cm 3.
In an alternative embodiment, in order to realize material mixing, material fiberization and material scattering in the granulator by controlling the stirring speed of the granulator, the granulator comprises 1, an outer cylinder, 2, an inner cylinder, 3, a water flow channel, 4, a cooling water inlet pipe, 5, a cooling water outlet pipe, 6, a stirring shaft, 7, a first rotary driver, 8, a large blade stirrer, 9, a small blade stirrer, 10, a temperature probe, 11, a second rotary driver, 12 and a cover. The cooling water cooling device comprises an outer cylinder 1, an inner cylinder 2 sleeved in the outer cylinder 1 and a cover 12 covered on the outer cylinder 1, wherein a water flow channel 3 is formed between the outer cylinder 1 and the inner cylinder 2, a water inlet and a water outlet are formed in the side wall of the outer cylinder 1, the water inlet and the water outlet are communicated with the water flow channel 3, the water inlet is connected with a cooling water inlet pipe 4, the water outlet is connected with a cooling water outlet pipe 5, control valves are arranged on the cooling water inlet pipe 4 and the cooling water outlet pipe 5, a stirring shaft 6 is arranged in the inner cylinder 2, the stirring shaft 6 is driven to rotate by a first rotary driver 7, a large-blade stirrer 8 and a small-blade stirrer 9 are sleeved on the stirring shaft 6, the small-blade stirrer 9 and the large-blade stirrer 8 are sequentially arranged along the direction close to the bottom of the inner cylinder 2, a temperature probe 10 is arranged in the inner cylinder 2, and the temperature probe 10 is connected with a temperature display positioned outside the outer cylinder 1, and can know the temperature in the inner cylinder 2 in real time through the temperature display, and the temperature in the inner cylinder 2 can be conveniently regulated and controlled by cooling water.
According to the granulator, the stirring speed of the stirring shaft 6 is controlled through the first rotary driver 7, so that the stirring effect of the large-blade stirrer 8 and the small-blade stirrer 9 is controlled, wherein the width and the length of the blades of the large-blade stirrer 8 are larger than those of the small-blade stirrer 9, and the double-layer blade type stirring effect is better; in addition, in the present embodiment, the blades of the large blade stirrer 8 have a certain sharpness, such as an arrow shape, so that the speed of the fiberizing stirring is reduced and the fiberizing time is also reduced.
In addition, the granulator is provided with the water flow channel 3, the cooling water inlet pipe 4 and the cooling water outlet pipe 5 which are communicated with the water flow channel 3, and whether cooling water exists in the water flow channel 3 or not can be controlled by controlling the control valve switch on the cooling water inlet pipe 4 and the cooling water outlet pipe 5, so that the temperature of powder in the inner barrel 2 can be controlled, and the temperature requirements of materials in different stages can be met.
The method for controlling the powder temperature in the step one comprises the steps of opening a control valve on a cooling water inlet pipe and a control valve on a cooling water outlet pipe to enable cooling water to be introduced into a water flow channel, the method for controlling the powder temperature in the step two comprises the steps of closing the control valve on the cooling water inlet pipe and keeping the control valve on the cooling water outlet pipe in an open state to enable cooling water to be absent in the water flow channel, and the method for controlling the powder temperature in the step three comprises the steps of opening the control valve on the cooling water inlet pipe and keeping the control valve on the cooling water outlet pipe in an open state to enable cooling water to be introduced into the water flow channel. The cooling water is controlled to regulate and control the heat generated by the stirring paddle in the stirring process, so that the material mixing, material fiberization and material scattering are completed in the granulator, and in addition, the heat generated by the stirring paddle in the high-speed stirring process is utilized to enable the binder to be mixed and fiberized simultaneously, so that the cutting and fiberization effects of the binder are facilitated, the fiberization effect of the high-speed stirrer with the structure is obviously superior to that of a common high-speed stirrer, and the binder can be fully fiberized.
In an alternative embodiment, in order to facilitate the stirring of the powder, and to avoid that excessive powder in the inner cylinder affects the stirring effect of the powder, the powder is added in the granulator in an amount of 40-70% of the volume of the inner cylinder.
In an alternative embodiment, in order to make the stirring efficiency higher and the particle size more uniform, the inner cylinder 2 is driven to rotate by the second rotary driver 11, the rotation direction of the second rotary driver 11 driving the inner cylinder 2 is opposite to the rotation direction of the first rotary driver 7 driving the stirring shaft 6, and in the process of mixing, the inner cylinder 2 rotates clockwise, the stirring shaft 6 rotates anticlockwise, and powder is scattered and mixed by countercurrent.
In a second aspect, the embodiment of the invention provides a processing method of an electrode plate, which comprises the steps of calendaring the electrode material into dry-method membranes, winding and unwinding the dry-method membranes, and laminating the dry-method membranes on two sides of a current collector through flat hot pressing to obtain the dry-method electrode plate.
In an alternative embodiment, the temperature of the flat plate hot press is 80-200 ℃, preferably 120-180 ℃.
When electrode materials are calendered to form films, the prepared dry film has uniform thickness and good consistency, solves the problems of holes or uneven edges on electrode plates, and the like, and improves the manufacturing rate and electrochemical performance of the secondary battery prepared by the method.
In a third aspect, an embodiment of the present invention provides a lithium ion battery, where the lithium ion battery includes the electrode plate described above.
The features and capabilities of the present invention are described in further detail below in connection with the examples.
Example 1
The NCM622 is adopted as a positive electrode active material, the SP is adopted as a conductive agent, the polytetrafluoroethylene is adopted as a binder, and the mass ratio of the positive electrode active material to the conductive agent to the binder is 96:2:2. And adding the positive electrode material and the conductive agent into a granulator according to the proportion.
Starting cooling water, and mixing at 1300rpm for 5min;
The cooling water is closed, the temperature of powder is controlled to be 95 ℃ at a high speed of 5800rpm, sampling is carried out every 2min, the bulk density of the mixed material is tested, the change curve of the bulk density of the mixed material with time can be obtained, the result is shown in figure 3, the bulk density of the mixed material is larger before 3min, the mixing uniformity of the material and the fibrosis degree of the binder are general, the mixing uniformity of the material is 3min-9min, the material is fluffy and flocculent, the fibrosis effect of the binder is good, the flocculent material starts to be broken after 9min, the fiber of the fibrous binder starts to break due to overlong mixing time, the bulk density is reduced and is similar to the bulk density (1.15 g/cm 3) of the positive electrode active material NCM622, the fibrosis of the binder is excessive, and the obtained material is hard to prepare a pole piece film and is difficult to press thin. Therefore, the materials with good fiberization effect in the period of 3-9 min are taken for scanning electron microscope test, and see fig. 4.
The cooling water was turned on and the powder was broken up at a low speed of 300rpm for 5 minutes, and the powder after the break up at a low speed was shown in FIG. 5.
The fibrillated electrode material was added to a vertical roll press and hot rolled at 120 ℃ to a set thickness to form a dry positive film, and a cross-sectional SEM image of the prepared film was seen in fig. 6. And (3) laminating the positive electrode film on two sides of the current collector through flat plate hot pressing, then cutting the positive electrode and the negative electrode respectively, and laminating to prepare the secondary battery.
According to the embodiment, in the processing process of the electrode material, the powder is primarily mixed according to the first medium-speed stirring, then the powder is stirred at a high speed, in the high-speed stirring process, the fluffy flocculent material with good fiberization effect is selected by monitoring the change of loose density, and finally the step of low-speed scattering is carried out, so that the electrode material with good mixing effect and uniform particle size can be prepared, and further the electrode material is adopted to prepare the electrode film with uniform thickness, better consistency and good appearance performance.
Example 2
Substantially the same as in example 1, except that the conductive agent was graphene in the dry electrode powder fiberizing process.
Example 3
Substantially the same as in example 1, except that the high-speed mixing in the dry electrode powder fiberizing process controlled the powder temperature to 120 ℃.
Example 4
Substantially the same as in example 1, except that the high-speed mixing in the dry electrode powder fiberizing process controlled the powder temperature to 150 ℃.
Example 5
Substantially the same as in example 1, except that the high-speed stirring speed was set to 5000rpm in the dry electrode powder fiberizing process.
Example 6
The procedure was substantially as in example 1, except that the high-speed stirring speed was set to 7000rpm in the dry electrode powder fiberizing process.
Example 7
The procedure was substantially as in example 1, except that the medium speed stirring speed was set to 1000rpm in the dry electrode powder fiberizing process.
Example 8
Substantially the same as in example 1, except that the medium speed stirring speed was set to 2000rpm in the dry electrode powder fiberizing process.
Example 9
Substantially the same as in example 1, except that a moderate speed mixing maintaining temperature of 25℃was set in the dry electrode powder fiberizing process.
Example 10
Substantially the same as in example 1, except that a moderate speed mixing maintaining temperature of 50℃was set in the dry electrode powder fiberizing process.
Example 11
Substantially the same as in example 1, except that the low-speed stirring speed was set to 100rpm in the dry electrode powder fiberizing process.
Example 12
Substantially the same as in example 1, except that the low-speed stirring speed was set to 500rpm in the dry electrode powder fiberizing process.
Example 13
Substantially the same as in example 1, except that the low-speed mixing maintaining temperature was set at 25℃in the dry electrode powder fiberizing process.
Example 14
Substantially the same as in example 1, except that the low-speed mixing maintaining temperature was set at 35℃in the dry electrode powder fiberizing process.
Comparative example 1
Substantially the same as in example 1, except that the positive electrode material and the conductive agent were not mixed at a medium speed (i.e., the positive electrode material, the conductive agent, and the binder were directly mixed at a high speed) in the dry electrode powder fiberizing process.
Comparative example 2
The procedure was substantially as in example 1, except that the medium speed stirring speed was set to 3000rpm in the dry electrode powder fiberizing process.
Comparative example 3
Substantially the same as in example 1, except that the mixed material was not stirred at high speed in the dry electrode powder fiberizing process.
Comparative example 4
Substantially the same as in example 1, except that the high-speed stirring speed was set to 8000rpm in the dry electrode powder fiberizing process.
Comparative example 5
Substantially the same as in example 1, except that the fibrillated mixed material was not subjected to low-speed scattering in the dry electrode powder fibrillation processing method.
Comparative example 6
Substantially the same as in example 1, except that the low-speed stirring speed was set to 1000rpm in the dry electrode powder fiberizing process.
Comparative example 7
Substantially the same as in example 1, except that a moderate speed mixing maintaining temperature of 80℃was set in the dry electrode powder fiberizing process.
Comparative example 8
Substantially the same as in example 1, except that a high-speed mixing maintaining temperature of 200℃was set in the dry electrode powder fiberizing process.
Comparative example 9
Substantially the same as in example 1, except that the low-speed mixing maintaining temperature was set at 60℃in the dry electrode powder fiberizing process.
And (3) testing:
2. Test method
1. Bulk density test:
1) The mass of the 250mL beaker was weighed and recorded as M1.
2) The beaker is filled with the sample to be measured, and the redundant sample on the beaker is scraped off by a straight ruler. This process should avoid vibration. The overall mass was then weighed and noted as M2.
3) The bulk density was calculated as follows:
BD=(M2-M1)/V
Wherein:
BD- -bulk density of the sample to be measured in g/cm 3;
M1- -mass of beaker in g;
M2- -the total mass of beaker and sample in g;
V- -volume of beaker in cm 3.
4) One sample was repeatedly measured three times, and the arithmetic average of the three measurements was taken as the apparent density value of the sample to be tested.
2. First effect and gram capacity test of button cell:
the dry pole piece is assembled into a button half battery, the electrolyte is LiPF 6/EC+DEC+DMC (volume ratio is 1:1:1), the metal lithium piece is a counter electrode, the diaphragm is a Polyethylene (PE), polypropylene (PP) or polyethylene propylene (PEP) composite film, and the button battery is assembled in a glove box filled with argon.
Specific capacity and first effect test:
1) Converting the constant-current charging into constant-voltage charging by 0.1C until the charging current is reduced to 0.05C, stopping charging, and standing for 30min;
2) Stopping discharging at a final voltage by constant current discharging at 0.1C, standing for 30min, and recording the specific discharge capacity as gram capacity of the dry pole piece;
3) The ratio of the first discharge capacity to the first charge capacity is taken as the first efficiency, and the charge-discharge cut-off voltage is 2.8-4.35V. The test results are shown in Table 1.
TABLE 1
As can be seen from the above Table 1, the powder materials provided in the examples and the comparative examples are respectively made into positive plates, the dry positive plates are respectively assembled into button half batteries, the positive plates prepared from the electrode material prepared in the examples of the invention have good apparent properties of the membranes, and the initial efficiency and gram capacity of the obtained button half batteries are also high, while the quality of the membranes in the comparative examples is poor, even the membranes cannot be formed into films, and the performances of the corresponding batteries are also poor. The electrode material processing process provided by the embodiment of the invention comprises the following steps of stirring at a medium speed to ensure that the used raw materials reach a preliminary uniform mixing state, then mixing at a high speed, closely monitoring the change of bulk density in the high-speed mixing process, obtaining a material with good fiberizing effect when the bulk density of powder meets 20% < BD t/BD0 <50%, scattering the material at a low speed after obtaining the material with good fiberizing effect, finally obtaining the electrode material with good mixing effect and uniform particle size, further preparing a pole piece film with good electrochemical performance by adopting the electrode material, laminating the pole piece film on two sides of a current collector by flat hot pressing, and then cutting and laminating the positive electrode and the negative electrode respectively to prepare the secondary battery.
When the above steps are not followed in the processing process of the electrode material or the temperature, time and speed in the stirring process are changed, the powder cannot reach the state required to be reached in each stage, the prepared powder is unevenly mixed and has poor effect, so that when the electrode material is used for calendaring and film forming, the quality of a film is poor, even film forming cannot be carried out (such as comparative example 3, comparative example 4 and comparative example 8), and the performance of the corresponding battery is poor. Therefore, by adopting the scheme provided by the embodiment of the invention, the electrode material with good mixing effect and uniform particle size can be obtained, and when the electrode material is calendered to form a film, the prepared film has uniform thickness and good consistency, and the problems of holes or uneven edges and the like on the electrode film are solved.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A method of processing an electrode material, comprising the steps of:
adding an electrode active material and a conductive agent into a granulator, adopting medium-speed stirring at 1000-2000rpm for 5-15min, controlling the temperature of powder to be 25-50 ℃ to obtain a uniform mixed material, and testing the apparent density of the mixed material to be BD 0;
Adding a binder into the mixed material, stirring at a high speed of 5000-7000rpm for 3-10min, controlling the temperature of powder to be 70-160 ℃ to obtain a fiberized material, and requiring the loose density BD t of the fiberized material when the test stirring time is t, wherein BD t＜BD0 is 20% < BD t/BD0 <50%;
and thirdly, scattering the fiberized material at a low speed of 100-500rpm, wherein the low-speed stirring time is 5-10min, the temperature of the powder is controlled at 25-35 ℃, and the electrode material with uniform particles is obtained, and the particle size of the electrode material is 0.2-5mm.
2. The method according to claim 1, wherein a mass ratio of the electrode active material, the conductive agent, and the binder is 80-98:1-5:1-10, wherein:
the adhesive is a fiberizable adhesive, and the adhesive comprises at least one of polyvinylidene fluoride, acrylic resin, polytetrafluoroethylene and styrene-butadiene rubber;
The conductive agent comprises at least one of acetylene black, conductive carbon black, ketjen black, graphene, carbon nanotubes and carbon fibers, and the loose density of the conductive agent is 0.05-0.2g/cm 3;
The electrode active material is a positive electrode material or a negative electrode material, the positive electrode material comprises at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium manganate, lithium cobaltate, lithium titanate and lithium nickel cobalt manganate, the loose packing density of the positive electrode material is 1.0-2.0g/cm 3, the negative electrode material comprises at least one of graphite, silicon oxide, hard carbon and soft carbon, and the loose packing density of the negative electrode material is 0.5-1.5g/cm 3.
3. The method according to claim 1, wherein in the second step, the loose density is measured by a scott volumetric method or a vibration hopper method.
4. The processing method according to claim 1, wherein the granulator in the first step comprises an outer cylinder, an inner cylinder sleeved in the outer cylinder and a cover covered on the outer cylinder, a water flow channel is formed between the outer cylinder and the inner cylinder, a water inlet and a water outlet are formed in the side wall of the outer cylinder, the water inlet and the water outlet are communicated with the water flow channel, the water inlet is connected with a cooling water inlet pipe, the water outlet is connected with a cooling water outlet pipe, control valves are arranged on the cooling water inlet pipe and the cooling water outlet pipe, a stirring shaft is arranged in the inner cylinder and driven to rotate by a first rotary driver, a large-blade stirrer and a small-blade stirrer are sleeved on the stirring shaft, the small-blade stirrer and the large-blade stirrer are sequentially arranged along the direction close to the bottom of the inner cylinder, and a temperature probe is arranged in the inner cylinder and connected with a temperature display located outside the outer cylinder.
5. The processing method according to claim 4, wherein the method for controlling the powder temperature in the first step is to open a control valve on a cooling water inlet pipe and a control valve on a cooling water outlet pipe to enable cooling water to be introduced into the water flow channel, the method for controlling the powder temperature in the second step is to close the control valve on the cooling water inlet pipe and keep the control valve on the cooling water outlet pipe in an open state to enable no cooling water to be in the water flow channel, and the method for controlling the powder temperature in the third step is to open the control valve on the cooling water inlet pipe and keep the control valve on the cooling water outlet pipe in an open state to enable cooling water to be introduced into the water flow channel.
6. The method of claim 4, wherein the inner barrel is rotated by a second rotary drive, the second rotary drive driving the inner barrel in a direction opposite to the direction in which the first rotary drive drives the agitator shaft.
7. The method for processing the electrode pole piece is characterized by comprising the steps of calendaring an electrode material into a dry film, winding and unwinding the dry film, and attaching the dry film on two sides of a current collector through flat hot pressing to obtain the dry electrode pole piece, wherein the electrode material is processed by the processing method according to any one of claims 1-6.
8. A lithium ion battery, characterized in that the lithium ion battery comprises an electrode sheet processed by the processing method according to claim 7.
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