CN116885109A - Pole piece forming process with dry-method diaphragm - Google Patents

Pole piece forming process with dry-method diaphragm Download PDF

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Publication number
CN116885109A
CN116885109A CN202310914052.9A CN202310914052A CN116885109A CN 116885109 A CN116885109 A CN 116885109A CN 202310914052 A CN202310914052 A CN 202310914052A CN 116885109 A CN116885109 A CN 116885109A
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China
Prior art keywords
press
roller
membrane
pole piece
press roller
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CN202310914052.9A
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Chinese (zh)
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黄庆怡
孙东岳
王凯
刘嘉兵
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Dongguan Songshanhu Jiatuo Intelligent Equipment Co ltd
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Dongguan Songshanhu Jiatuo Intelligent Equipment Co ltd
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Priority to CN202310914052.9A priority Critical patent/CN116885109A/en
Publication of CN116885109A publication Critical patent/CN116885109A/en
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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
    • 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

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The application discloses a pole piece forming process with a dry membrane, and relates to the technical field of battery production; the method comprises the following steps: s10, mixing a main material of a material layer and a conductive agent, and rotating and mixing in a mixer to scatter the conductive agent and coat the conductive agent on the surfaces of main material particles to obtain a mixture; s20, adding polymer fibers when the temperature of the mixture is between 0 and 20 ℃, and mixing the mixture and the polymer fibers in a mixer to ensure that the temperature reaches between 40 and 99 ℃ to obtain a bulk and sticky mixed mass; s30, stirring and rotating the mixed mass in a mixer to obtain a uniform granular mixed mass with the particle size of 1 mm-3 mm; s40, rolling the granular mixed aggregate to form a membrane, and compounding the membrane with a current collector through rolling to obtain the pole piece. The application has the beneficial effects that: the mixed aggregate manufactured by the process can be rolled into a film at one time, so that the strength of the film is improved, and the film can be directly transferred to a current collector.

Description

Pole piece forming process with dry-method diaphragm
Technical Field
The application relates to the technical field of battery production, in particular to a pole piece forming process with a dry membrane.
Background
The lithium battery pole piece is composed of a current collector and a positive and negative electrode material layer on the surface of the current collector, the positive and negative electrode material slurry is coated on the current collector by the traditional pole piece manufacturing method, and then the positive or negative electrode material layer is formed by baking and solidifying the current collector by an oven, so that a large amount of energy is required for solvent recovery, the efficiency is low, and the environmental pollution can be caused. In order to solve the above problems, some manufacturers propose a method of manufacturing a positive electrode or a negative electrode material layer by a dry method, and then compounding a supported positive electrode material layer or a supported negative electrode material layer film with a current collector to form a pole piece.
However, in the existing dry electrode process, the fibrillated material is difficult to directly prepare into a self-supporting membrane, for example, the fibrillated material is fibrillated in a jet milling mode, the degree of the fibrillating is difficult to control, and partial components are lost in equipment, so that the discharge proportion is inconsistent. And the powder obtained by stirring is loose, and is directly calendered into a film, so that the strength and the compaction density of the film are improved greatly.
Disclosure of Invention
In order to overcome the defects of the prior art, the application provides a pole piece forming process with a dry-method membrane, which is rolled into a membrane once, improves the strength of the membrane and can be directly transferred to a current collector.
The technical scheme adopted for solving the technical problems is as follows: in a process for forming a pole piece with a dry film, the improvement comprising the steps of:
s10, mixing a main material of a material layer and a conductive agent, and rotating and mixing in a mixer to scatter the conductive agent and coat the conductive agent on the surfaces of main material particles to obtain a mixture;
s20, adding polymer fibers when the temperature of the mixture is between 0 and 20 ℃, and mixing the mixture and the polymer fibers in a mixer to ensure that the temperature reaches between 40 and 99 ℃ to obtain a bulk and sticky mixed mass;
s30, stirring and rotating the mixed mass material in a mixer to obtain uniform granular materials with the diameter of 1mm to 3 mm;
and S40, rolling the granular materials to form a membrane, and compounding the membrane with a current collector through rolling to obtain the pole piece.
In the above technical solution, the material layer in step S10 is a positive electrode material layer or a negative electrode material layer, and the main material of the positive electrode material layer includes at least one of nickel-cobalt-manganese ternary, lithium cobaltate, lithium iron phosphate, layered oxide, and polyanion positive electrode material; the main material of the negative electrode material layer comprises at least one of graphite, silicon carbon, silicon oxygen and hard carbon.
In the technical scheme, the main material of the material layer and the conductive agent in the step S10 are mixed in a mixer for 10-15 min, the rotating speed of the rotor is not less than 1000rpm, and the temperature is controlled at 25-35 ℃.
In the above technical solution, the rotor and the drum of the mixer in step S10 rotate in opposite directions.
In the technical scheme, the rotating speed of the rotor is kept at 1500-3750 rpm during mixing in the step S20, and the mixing time is 10-20 min.
In the above technical scheme, in step S30, the rotor and the drum of the mixer rotate in the same direction, and the rotation speed of the rotor is 50 rpm-1000 rpm.
In the above technical scheme, step S20 is followed by step S21, where step S21 is that the inner rotor of the mixer rotates at a rotation speed of 50 rpm-500 rpm, so that the mixed mass is more compact.
The rolling and film lamination of the granular material in step S40 in the above technical solution is achieved by the following method, which includes the following steps:
s401, arranging at least two rotatable press rolls side by side at intervals, wherein the rotation directions of adjacent press rolls are opposite, and the adjacent press rolls have temperature difference and rotation speed difference;
s402, extending the granular materials from the intervals of the press rolls into the space between the adjacent press rolls, alternately shuttling the granular materials at the intervals of the plurality of press rolls, and forming a membrane by the rolling of the plurality of press rolls;
s403, after or during the process of rolling the granular material into the membrane, extending the current collector and the membrane into the interval between the same adjacent press rollers in the same direction, so that the membrane is compounded on the current collector to form a pole piece.
In the technical scheme, when the number of the press rolls is three and the material layer main material is the positive electrode material layer main material, the three press rolls are a first press roll, a second press roll and a third press roll respectively, and the distance between the first press roll, the second press roll and the third press roll is set to be 0-2 mm; when the granular material forms a membrane firstly and then is compounded with the current collector, the roller temperature of the first compression roller and the second compression roller is set to be 60-250 ℃, the roller temperature of the third compression roller is set to be 0-250 ℃, the granular material alternately shuttles through the interval parts of the first compression roller, the second compression roller and the third compression roller to form the membrane and then is taken out, and then is compounded with the current collector through rolling between the compression rollers; when the granular material forms a membrane and the current collector is compounded to form a pole piece in the same step, the roller temperature of the first press roller and the second press roller is set to be 60-250 ℃, the roller temperature of the third press roller is set to be 0-200 ℃, the granular material is rolled at the interval of the first press roller and the second press roller to form the membrane, and the membrane and the current collector are extended into the second press roller and the third press roller to be compounded to form the pole piece in the same direction at the interval of the second press roller and the third press roller.
In the technical scheme, when the number of the press rolls is three and the material layer main material is the negative electrode material layer main material, the three press rolls are respectively a first press roll, a second press roll and a third press roll, and the distance between the first press roll, the second press roll and the third press roll is set to be 0-2 mm; when the granular material forms a membrane firstly and then is compounded with the current collector, the roller temperature of the first compression roller and the second compression roller is set to be 60-250 ℃, the roller temperature of the third compression roller is set to be 0-200 ℃, the granular material alternately shuttles through the interval parts of the first compression roller, the second compression roller and the third compression roller to form the membrane and then is taken out, and then is compounded with the current collector through rolling between the compression rollers; when the granular material forms a membrane and the current collector is compounded to form a pole piece in the same step, the roller temperature of the first press roller and the second press roller is set to be 60-250 ℃, the roller temperature of the third press roller is set to be 0-200 ℃, the granular material is rolled at the interval of the first press roller and the second press roller to form the membrane, and the membrane and the current collector are extended into the second press roller and the third press roller to be compounded to form the pole piece in the same direction at the interval of the second press roller and the third press roller.
The beneficial effects of the application are as follows: according to the application, the main material of the material layer is mixed with the conductive agent and the polymer fiber and forms the granular material under the stirring of the mixer, so that the material layer can be uniformly fed, the surface density uniformity is improved during rolling, and the prepared granular material has high strength after once calendaring and film forming, and is transversely and longitudinally strong, so that the material layer is beneficial to tape feeding.
Drawings
Fig. 1 is a process flow diagram of a pole piece forming process with dry film.
Fig. 2 is a schematic diagram of a structure of a film roll in a process of forming a pole piece with a dry film according to the present application.
Fig. 3 is a schematic diagram of a structure of a membrane and a current collector in a process of forming a pole piece with a dry membrane according to the present application.
Detailed Description
The application will be further described with reference to the drawings and examples.
The conception, specific structure, and technical effects produced by the present application will be clearly and completely described below with reference to the embodiments and the drawings to fully understand the objects, features, and effects of the present application. It is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments, and that other embodiments obtained by those skilled in the art without inventive effort are within the scope of the present application based on the embodiments of the present application. In addition, all the coupling/connection relationships referred to in the patent are not direct connection of the single-finger members, but rather, it means that a better coupling structure can be formed by adding or subtracting coupling aids depending on the specific implementation. The technical features in the application can be interactively combined on the premise of no contradiction and conflict.
Embodiment one: referring to fig. 1, as shown, the present application provides a pole piece forming process with a dry film sheet, comprising the steps of:
s10, mixing the main material of the material layer and the conductive agent, and rotating and mixing the materials in a mixer at the rotating speed of 1200rpm for 10min, wherein the rotor and the rotary drum of the mixer reversely rotate, the temperature is controlled at 25 ℃, so that the conductive agent is scattered and coated on the surfaces of the main material particles, and the mixture is obtained.
The material layer is a positive electrode material layer or a negative electrode material layer, and is adopted when the positive electrode plate is produced, and is adopted when the negative electrode plate is produced. The main material of the positive electrode material layer comprises at least one of nickel cobalt manganese ternary, lithium cobaltate, lithium iron phosphate, layered oxide and polyanion positive electrode material. The main material of the negative electrode material layer comprises at least one of graphite, silicon carbon, silicon oxygen and hard carbon. In this embodiment, the material layer is exemplified by a positive electrode material layer, and the main material is nickel-cobalt-manganese ternary.
And S20, adding polymer fibers when the temperature of the mixture is reduced to 13 ℃, wherein the polymer fibers are PTFE materials, mixing the mixture and the polymer fibers in a mixer, and keeping the rotating speed of a rotor at 1500rpm during mixing for 10min to ensure that the temperature of the mixed material and the PTEE materials reaches 45 ℃ after mixing to obtain a bulk and sticky mixed mass.
S21, continuously rotating the mixed mass material in the mixer at the rotating speed of 50rpm, so that the mixed mass material is more compact, the density of the mixed mass material is improved, and the strength of a film after film formation is improved.
S30, stirring and rotating the mixed mass in a mixer, wherein a rotor and a rotary drum of the mixer rotate in the same direction, the rotating speed of the rotor is 50rpm, uniform granular materials with the diameter of 1 mm-3 mm are obtained, uniform feeding of the granular materials during subsequent film forming is formed, and the uniformity of the surface density is improved.
And S40, rolling the granular materials to form a membrane, and compounding the membrane with a current collector through rolling to obtain the pole piece.
According to the application, after the main material of the material layer, the conductive agent and the polymer fiber are mixed under the setting of the specific rotation speed, the temperature time and other parameters, the formed granular material is beneficial to film formation, the formed film has strength in the transverse and longitudinal directions, the tape feeding is facilitated, and the formed pole piece has stable quality and high strength. Compared with the method using jet milling, the method provided by the application has the advantages that equipment is less, a mixer is used for realizing kneading and granulating effects, and process equipment is reduced.
Specifically, the film forming and pole piece compounding of the granular materials in the step S40 are realized by the following method, and the method comprises the following steps:
s401, arranging at least two rotatable press rolls side by side at intervals, wherein the rotation directions of adjacent press rolls are opposite, and the adjacent press rolls have a temperature difference and a rotation speed difference. The adjacent compression rollers rotate in opposite directions, the driving directions of the granular materials by the adjacent compression rollers are consistent when the granular materials are placed between the compression rollers, and the granular materials are driven to move and are extruded to form a film when the compression rollers rotate. And the adjacent compression rollers have temperature difference and rotation speed difference, the temperature difference is different between the adjacent compression rollers, the rotation speed difference is different between the adjacent compression rollers, the granular materials are automatically attached to different compression rollers when the compression rollers shuttle through the temperature difference and the rotation speed difference, automatic film forming is realized, and manual traction on the film is not needed.
And S402, extending the granular materials from the intervals of the press rolls into the space between the adjacent press rolls, alternately shuttling at the intervals of the plurality of press rolls, and forming a film sheet by the rolling of the plurality of press rolls. The granular material produced by the process provided by the application has high strength and high density, the film formed by the press rolls also has the characteristics of high strength and high density, the film cannot be loosened and shed when being extruded between the press rolls to form a film, the film can be successfully pressed by one time, and the film has strength in the transverse direction and the longitudinal direction, so that the film is beneficial to shuttle forming between the press rolls. The pressure of the film formed by adopting the compression roller is kept consistent with that of the granular materials, the formed film is more uniform, the quality of the product tends to be consistent, the high-strength mixed aggregate produced by the process has the characteristics of low damage rate, and the yield of the produced pole piece is high.
S403, after or during the process of rolling the granular material into the membrane, extending the current collector and the membrane into the interval between the same adjacent press rollers in the same direction, so that the membrane is compounded on the current collector to form a pole piece. Furthermore, the forming and compounding of the films can be synchronously carried out in a mode of arranging the compression rollers side by side, so that the production efficiency is improved.
For different production cases of film formation and compounding, the present application provides an embodiment in which when the number of press rolls is three and the material layer main material is the positive electrode material layer main material, the three press rolls are the first press roll 30, the second press roll 20, and the third press roll 10, respectively, and the distances between the first press roll 30, the second press roll 20, and the third press roll 10 are set to 1mm. The setting of the interval distance is considered to be in accordance with the required size of the formed membrane, and the interval can drive the granular materials to drag and shuttle between the compression rollers by the compression rollers without manual traction.
Referring to fig. 2, when the granular material 40 is formed into a film sheet and then the film sheet 50 is combined with a current collector, the temperature of the first press roller 30 is set to 60 ℃, the temperature of the second press roller 20 is set to 80 ℃, the temperature of the third press roller 10 is set to 20 ℃, and the rotation speed ratio of the three press rollers is 3:5:7, the granular material 40 alternately shuttles through the intervals of the first compression roller 30, the second compression roller 20 and the third compression roller 10 to form a film sheet 50, and then is taken out and then is subjected to rolling compounding with a current collector through the compression rollers. Because the membrane 50 is formed first and then compounded, in the film forming stage, the three press rollers pass through different rotating speeds, so that the granular materials are automatically pulled between the second press roller 20 and the third press roller 10 from the first press roller 30 to the second press roller 20 in the film forming process to form the membrane 50, and then the membrane 50 is pulled between the press rollers and the current collector together extend into the interval of the same adjacent press roller to carry out rolling compounding.
Referring to fig. 3, when the granular material 40 forms the film sheet 50 and the current collector 60 is compounded to form the pole piece in the same step, the roller temperature of the first press roller 30 is set to 60 ℃, the roller temperature of the second press roller 20 is set to 80 ℃, the roller temperature of the third press roller 10 is set to 50 ℃, and the rotation speed ratio of the three press rollers is 3:5:7, rolling the granular material 40 at the interval between the first compression roller 30 and the second compression roller 20 to form a film sheet 50, and extending the film sheet 50 and the current collector 60 into the space between the second compression roller 20 and the third compression roller 10 in the same direction at the interval between the second compression roller 20 and the third compression roller 10 to form a pole piece in a compounding way. Because the forming of the film 50 and the compounding of the pole piece are synchronously performed, the film is pressed and formed when the granular material 40 passes through the interval between the first press roller 30 and the second press roller 20, the film 50 formed by the granular material 40 passes through the interval between the second press roller 20 and the third press roller 10 under the driving of the temperature difference, the rotating speed difference and the press roller, at the moment, the current collector 60 extends into the interval between the second press roller 20 and the third press roller 10 in the same direction, the film 50 and the current collector 60 are compounded together under the pressing of the second press roller 20 and the third press roller 10 to form the pole piece, and compared with the film which is formed before the compounding, the film is thicker in the pole piece formed in the mode, the corresponding pole piece material layer formed when the film forming and the compounding are separated is thinner, and different technological requirements use different modes to form the pole piece.
In addition, the production of the anode and the cathode is different, when the number of the press rolls is three and the material layer main material is the cathode material layer main material, the three press rolls are a first press roll, a second press roll and a third press roll respectively, and the distance among the first press roll, the second press roll and the third press roll is set to be 1mm.
When the granular material forms a membrane firstly and then is compounded with the current collector, the roller temperature of the first press roller is set to 60 ℃, the roller temperature of the second press roller is set to 80 ℃, the roller temperature of the third press roller is set to 50 ℃, the granular material alternately shuttles through the intervals of the first press roller, the second press roller and the third press roller to form the membrane and then is taken out, and then is compounded with the current collector through rolling between the press rollers.
When the granular material forms a membrane and the current collector is compounded to form a pole piece in the same step, the roller temperature of the first press roller is set to 60 ℃, the roller temperature of the second press roller is set to 80 ℃, the roller temperature of the third press roller is set to 40 ℃, the granular material is rolled at the interval of the first press roller and the second press roller to form the membrane, and the membrane and the current collector extend into the space between the second press roller and the third press roller in the same direction at the interval of the second press roller and the third press roller to be compounded to form the pole piece. Specifically, the temperature requirements of the third press roller are different, and different temperatures are needed to achieve a better tape feeding effect corresponding to different main materials of the negative electrode material layer.
Embodiment two: the embodiment provides a pole piece forming process with a dry membrane, which comprises the following steps:
s10, mixing the main material of the material layer and the conductive agent, and rotating and mixing the materials in a mixer at a rotating speed of 1600rpm for 13min, wherein the rotor and the rotary drum of the mixer reversely rotate, the temperature is controlled at 30 ℃, and the conductive agent is scattered and coated on the surfaces of the main material particles to obtain the mixture.
The material layer is a positive electrode material layer or a negative electrode material layer, and is adopted when the positive electrode plate is produced, and is adopted when the negative electrode plate is produced. The main material of the positive electrode material layer comprises at least one of nickel cobalt manganese ternary, lithium cobaltate, lithium iron phosphate, layered oxide and polyanion positive electrode material. The main material of the negative electrode material layer comprises at least one of graphite, silicon carbon, silicon oxygen and hard carbon. In this embodiment, the material layer is exemplified by a positive electrode material layer, and the main material is nickel-cobalt-manganese ternary.
And S20, adding polymer fibers when the temperature of the mixture is reduced to 16 ℃, wherein the polymer fibers are PTFE materials, mixing the mixture and the polymer fibers in a mixer, and keeping the rotating speed of a rotor at 1800rpm during mixing for 15min to ensure that the temperature of the mixed material and the PTEE materials reaches 65 ℃ after mixing to obtain a bulk and sticky mixed material.
S21, continuously rotating the mixed mass material in the mixer at the rotating speed of 250rpm, so that the mixed mass material is more compact, the density of the mixed mass material is improved, and the strength of a film after film formation is improved.
S30, stirring and rotating the mixed mass in a mixer, wherein a rotor and a rotary drum of the mixer rotate in the same direction, the rotating speed of the rotor is 500rpm, uniform granular materials with the diameter of 1 mm-3 mm are obtained, the granular materials can be uniformly fed during subsequent film forming, and the uniformity of the surface density is improved.
And S40, rolling the granular materials to form a membrane, and compounding the membrane with a current collector through rolling to obtain the pole piece.
According to the application, after the main material of the material layer, the conductive agent and the polymer fiber are mixed under the setting of the specific rotation speed, the temperature time and other parameters, the formed granular material is beneficial to film formation, the formed film has strength in the transverse and longitudinal directions, the tape feeding is facilitated, and the formed pole piece has stable quality and high strength. Compared with the method using jet milling, the method provided by the application has the advantages that equipment is less, a mixer is used for realizing kneading and granulating effects, and process equipment is reduced.
Specifically, the film forming and pole piece compounding of the granular materials in the step S40 are realized by the following method, and the method comprises the following steps:
s401, arranging at least two rotatable press rolls side by side at intervals, wherein the rotation directions of adjacent press rolls are opposite, and the adjacent press rolls have a temperature difference and a rotation speed difference. The adjacent compression rollers rotate in opposite directions, the driving directions of the granular materials by the adjacent compression rollers are consistent when the granular materials are placed between the compression rollers, and the granular materials are driven to move and are extruded to form a film when the compression rollers rotate. And the adjacent compression rollers have temperature difference and rotation speed difference, the temperature difference is different between the adjacent compression rollers, the rotation speed difference is different between the adjacent compression rollers, the granular materials are automatically attached to different compression rollers when the compression rollers shuttle through the temperature difference and the rotation speed difference, automatic film forming is realized, and manual traction on the film is not needed.
And S402, extending the granular materials from the intervals of the press rolls into the space between the adjacent press rolls, alternately shuttling at the intervals of the plurality of press rolls, and forming a film sheet by the rolling of the plurality of press rolls. The granular material produced by the process provided by the application has high strength and high density, the film formed by the press rolls also has the characteristics of high strength and high density, the film cannot be loosened and shed when being extruded between the press rolls to form a film, the film can be successfully pressed by one time, and the film has strength in the transverse direction and the longitudinal direction, so that the film is beneficial to shuttle forming between the press rolls. The pressure of the film formed by adopting the compression roller is kept consistent with that of the granular material, the formed film is more uniform, the quality of the product tends to be consistent, the high-strength granular material produced by the process has the characteristics of low damage rate and high yield of the produced pole pieces.
S403, after or during the process of rolling the granular material into the membrane, extending the current collector and the membrane into the interval between the same adjacent press rollers in the same direction, so that the membrane is compounded on the current collector to form a pole piece. Furthermore, the forming and compounding of the films can be synchronously carried out in a mode of arranging the compression rollers side by side, so that the production efficiency is improved.
For different production conditions of film forming and compounding, the application provides an embodiment, when the number of the press rolls is three and the material layer main material is the positive electrode material layer main material, the three press rolls are respectively a first press roll, a second press roll and a third press roll, and the distance between the first press roll, the second press roll and the third press roll is set to be 1.5mm. The setting of the interval distance is considered to be in accordance with the required size of the formed membrane, and the interval can drive the granular materials to drag and shuttle between the compression rollers by the compression rollers without manual traction.
Referring to fig. 2, when the granular material 40 is formed into the film sheet 50 and then the film sheet 50 is combined with the current collector, the roller temperature of the first press roller 30 is set to 100 ℃, the roller temperature of the second press roller 20 is set to 130 ℃, the roller temperature of the third press roller 10 is set to 150 ℃, and the rotation speed ratio of the three press rollers is 3:5:8, the granular material 40 alternately shuttles through the intervals of the first compression roller 30, the second compression roller 20 and the third compression roller 10 to form a membrane 50, and then is taken out and then is subjected to rolling compounding with a current collector through the compression rollers. Because the membrane 50 is formed first and then compounded, the three press rollers pass through different rotating speeds in the film forming stage, the granular material is automatically pulled between the second press roller and the third press roller from the first press roller to the second press roller in the film forming process to form the membrane, and then the membrane is pulled between the press rollers and the current collector is extended into the interval of the same adjacent press roller together for rolling and compounding.
Referring to fig. 3, when the granular material 40 forms the film sheet 50 and the current collector 60 is compounded to form the pole piece in the same step, the roller temperature of the first press roller 30 is set to 100 ℃, the roller temperature of the second press roller 20 is set to 130 ℃, the roller temperature of the third press roller 10 is set to 110 ℃, and the rotation speed ratio of the three press rollers is 3:5:8, the granular material 40 is rolled at the interval of the first pressing roller 30 and the second pressing roller 20 to form a film sheet 50, and the film sheet 50 and the current collector 60 are extended into the space between the second pressing roller 20 and the third pressing roller 10 in the same direction at the interval of the second pressing roller 20 and the third pressing roller 10 to be composited to form a pole piece. Because the forming of the film 50 and the compounding of the pole piece are synchronously performed, the film 50 is pressed when the granular material 40 passes through the interval between the first press roller 30 and the second press roller 20, the film 50 formed by the granular material 40 passes through the interval between the second press roller 20 and the third press roller 10 under the driving of the temperature difference, the rotating speed difference and the press roller, at the moment, the current collector 60 extends into the interval between the second press roller 20 and the third press roller 10 in the same direction, the film 50 and the current collector 60 are compounded together under the rolling of the second press roller 20 and the third press roller 10 to form the pole piece, compared with the mode that the film 50 is formed firstly and then compounded, the film 50 in the pole piece formed in the mode is thicker, the corresponding pole piece material layer formed when film forming and compounding are separated is thinner, and different processes require the pole piece formed in different modes.
In addition, the production of the anode and the cathode is different, when the number of the press rolls is three and the material layer main material is the cathode material layer main material, the three press rolls are a first press roll, a second press roll and a third press roll respectively, and the distance among the first press roll, the second press roll and the third press roll is set to be 1.5mm.
When the granular material forms a film firstly and then is compounded with the current collector, the roller temperature of the first press roller is set to be 100 ℃, the roller temperature of the second press roller is set to be 130 ℃, the roller temperature of the third press roller is set to be 110 ℃, the granular material alternately shuttles through the intervals of the first press roller, the second press roller and the third press roller to form the film, then the film is taken out, and then the film and the current collector are compounded by rolling through the press rollers.
When the granular material forms a membrane and the current collector is compounded to form a pole piece in the same step, the roller temperature of the first press roller is set to 100 ℃, the roller temperature of the second press roller is set to 130 ℃, the roller temperature of the third press roller is set to 100 ℃, the granular material is rolled at the interval of the first press roller and the second press roller to form the membrane, and the membrane and the current collector extend into the space between the second press roller and the third press roller in the same direction at the interval of the second press roller and the third press roller to be compounded to form the pole piece. Specifically, the temperature requirements of the third press roller are different, and different temperatures are needed to achieve a better tape feeding effect corresponding to different main materials of the negative electrode material layer.
Embodiment III: the embodiment provides a pole piece forming process with a dry membrane, which comprises the following steps:
s10, mixing the main material of the material layer and the conductive agent, and rotating and mixing the materials in a mixer at a rotating speed of 2000rpm for 15min, wherein the rotor and the rotary drum of the mixer reversely rotate, and the temperature is controlled at 35 ℃ so that the conductive agent is scattered and coated on the surfaces of the main material particles, thereby obtaining the mixture.
The material layer is a positive electrode material layer or a negative electrode material layer, and is adopted when the positive electrode plate is produced, and is adopted when the negative electrode plate is produced. The main material of the positive electrode material layer comprises at least one of nickel cobalt manganese ternary, lithium cobaltate, lithium iron phosphate, layered oxide and polyanion positive electrode material. The main material of the negative electrode material layer comprises at least one of graphite, silicon carbon, silicon oxygen and hard carbon. In this embodiment, the material layer is exemplified by a negative electrode material layer, and the main material is graphite.
S20, adding polymer fibers when the temperature of the mixture is reduced to 20 ℃, mixing the mixture and the polymer fibers in a mixer, wherein the rotor keeps the rotating speed at 3500rpm during mixing, and the mixing time is 20min, so that the temperature of the mixed material and the PTEE material reaches 96 ℃, and a bulk and sticky mixed material is obtained.
S21, continuously rotating the mixed mass material in the mixer at the rotating speed of 480rpm, so that the mixed mass material is more compact, the density of the mixed mass material is improved, and the strength of a film after film formation is improved.
S30, stirring and rotating the mixed mass in a mixer, wherein a rotor and a rotary drum of the mixer rotate in the same direction, the rotating speed of the rotor is 900rpm, and 1-3 mm uniform granular materials are obtained, so that the granular materials can be uniformly fed during subsequent film forming, and the uniformity of the surface density is improved.
And S40, rolling the granular materials to form a membrane, and compounding the membrane with a current collector through rolling to obtain the pole piece.
According to the application, after the main material of the material layer, the conductive agent and the polymer fiber are mixed under the setting of the specific rotation speed, the temperature time and other parameters, the formed granular material is beneficial to film formation, the formed film has strength in the transverse and longitudinal directions, the tape feeding is facilitated, and the formed pole piece has stable quality and high strength. Compared with the method using jet milling, the method provided by the application has the advantages that equipment is less, a mixer is used for realizing kneading and granulating effects, and process equipment is reduced.
Specifically, the film forming and pole piece compounding of the granular materials in the step S40 are realized by the following method, and the method comprises the following steps:
s401, arranging at least two rotatable press rolls side by side at intervals, wherein the rotation directions of adjacent press rolls are opposite, and the adjacent press rolls have a temperature difference and a rotation speed difference. The adjacent compression rollers rotate in opposite directions, the driving directions of the granular materials by the adjacent compression rollers are consistent when the granular materials are placed between the compression rollers, and the granular materials are driven to move and are extruded to form a film when the compression rollers rotate. And the adjacent compression rollers have temperature difference and rotation speed difference, the temperature difference is different between the adjacent compression rollers, the rotation speed difference is different between the adjacent compression rollers, the granular materials are automatically attached to different compression rollers when the compression rollers shuttle through the temperature difference and the rotation speed difference, automatic film forming is realized, and manual traction on the film is not needed.
And S402, extending the granular materials from the intervals of the press rolls into the space between the adjacent press rolls, alternately shuttling at the intervals of the plurality of press rolls, and forming a film sheet by the rolling of the plurality of press rolls. The granular material produced by the process provided by the application has high strength and high density, the film formed by the press rolls also has the characteristics of high strength and high density, the film cannot be loosened and shed when being extruded between the press rolls to form a film, the film can be successfully pressed by one time, and the film has strength in the transverse direction and the longitudinal direction, so that the film is beneficial to shuttle forming between the press rolls. The pressure of the film formed by adopting the compression roller is kept consistent with that of the granular material, the formed film is more uniform, the quality of the product tends to be consistent, the high-strength granular material produced by the process has the characteristics of low damage rate and high yield of the produced pole pieces.
S403, after or during the process of rolling the granular material into the membrane, extending the current collector and the membrane into the interval between the same adjacent press rollers in the same direction, so that the membrane is compounded on the current collector to form a pole piece. Furthermore, the forming and compounding of the films can be synchronously carried out in a mode of arranging the compression rollers side by side, so that the production efficiency is improved.
For different production conditions of film forming and compounding, the application provides an embodiment, when the number of the press rolls is three and the material layer main material is the positive electrode material layer main material, the three press rolls are respectively a first press roll, a second press roll and a third press roll, and the distance between the first press roll, the second press roll and the third press roll is set to be 1.5mm. The setting of the interval distance is considered to be in accordance with the required size of the formed membrane, and the interval can drive the mixed mass to drag and shuttle between the compression rollers by the compression rollers without manual traction.
Referring to fig. 2, when the granular material 40 is formed into the film sheet 50 and then the film sheet 50 is combined with the current collector, the roller temperature of the first press roller 30 is set to 150 ℃, the roller temperature of the second press roller 20 is set to 200 ℃, the roller temperature of the third press roller 10 is set to 230 ℃, and the rotation speed ratio of the three press rollers is 3:5:9, the granular material 40 alternately shuttles through the intervals of the first compression roller 30, the second compression roller 20 and the third compression roller 10 to form a membrane 50, and then is taken out and then is subjected to rolling compounding with a current collector through the compression rollers. The membrane is formed firstly and then compounded, and the three press rollers pass through different rotating speeds in the film forming stage, so that the granular materials are automatically pulled between the second press roller and the third press roller from the first press roller to the second press roller in the film forming process to form the membrane, and then the membrane is pulled between the press rollers and the current collector are extended into the interval of the same adjacent press roller together for rolling and compounding.
Referring to fig. 3, when the granular material 40 forms the film sheet 50 and the current collector 60 is compounded to form the pole piece in the same step, the roller temperature of the first press roller 30 is set to 150 ℃, the roller temperature of the second press roller 20 is set to 200 ℃, the roller temperature of the third press roller 10 is set to 180 ℃, and the rotation speed ratio of the three press rollers is 3:5:9, rolling the granular material 40 at the interval of the first compression roller 30 and the second compression roller 20 to form a film sheet 50, and extending the film sheet 50 and the current collector 60 into the space of the second compression roller 20 and the third compression roller 10 in the same direction at the interval of the second compression roller 20 and the third compression roller 10 to be composited to form a pole piece. Because the forming of the film 50 and the compounding of the pole piece are synchronously performed, the film is pressed and formed when the granular material 40 passes through the interval between the first press roller 30 and the second press roller 20, the film 50 formed by the granular material 40 passes through the interval between the second press roller 20 and the third press roller 10 under the driving of the temperature difference, the rotating speed difference and the press roller, at the moment, the current collector 60 extends into the interval between the second press roller 20 and the third press roller 10 in the same direction, the film 50 and the current collector 60 are compounded together under the pressing of the second press roller 20 and the third press roller 10 to form the pole piece, and compared with the film which is formed before the compounding, the film is thicker in the pole piece formed in the mode, the corresponding pole piece material layer formed when the film forming and the compounding are separated is thinner, and different technological requirements use different modes to form the pole piece.
In addition, the production of the anode and the cathode is different, when the number of the press rolls is three and the material layer main material is the cathode material layer main material, the three press rolls are a first press roll, a second press roll and a third press roll respectively, and the distance among the first press roll, the second press roll and the third press roll is set to be 2mm.
When the granular material forms a membrane firstly and then is compounded with the current collector, the roller temperature of the first press roller is set to 150 ℃, the roller temperature of the second press roller is set to 200 ℃, the roller temperature of the third press roller is set to 180 ℃, the granular material alternately shuttles through the intervals of the first press roller, the second press roller and the third press roller to form the membrane and then is taken out, and then is compounded with the current collector through rolling between the press rollers.
When the granular material forms a membrane and the current collector is compounded to form a pole piece in the same step, the roller temperature of the first press roller is set to 120 ℃, the roller temperature of the second press roller is set to 200 ℃, the roller temperature of the third press roller is set to 180 ℃, the granular material is rolled at the interval of the first press roller and the second press roller to form the membrane, and the membrane and the current collector extend into the space between the second press roller and the third press roller in the same direction at the interval of the second press roller and the third press roller to be compounded to form the pole piece. Specifically, the temperature requirements of the third press roller are different, and different temperatures are needed to achieve a better tape feeding effect corresponding to different main materials of the negative electrode material layer.
In another embodiment, the number of the compression rollers can be two, a spacing gap exists between the two compression rollers, the granular materials are rolled into a film sheet through the spacing gap, then the current collector and the film sheet extend together into the spacing gap to be composited into the pole piece, or the granular materials and the current collector extend together into the spacing gap, and the granular materials are composited with the current collector to be formed into the pole piece while being formed into the film sheet, so that the forming method is suitable for the requirement of a thick film sheet. Different numbers of press rolls are arranged corresponding to different requirements, so that the production requirement is met.
While the preferred embodiment of the present application has been described in detail, the present application is not limited to the embodiments, and those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present application, and the equivalent modifications or substitutions are included in the scope of the present application as defined in the appended claims.

Claims (12)

1. The pole piece forming process with the dry membrane is characterized by comprising the following steps of:
s10, mixing a main material of a material layer and a conductive agent, and rotating and mixing in a mixer to scatter the conductive agent and coat the conductive agent on the surfaces of main material particles to obtain a mixture;
s20, adding polymer fibers when the temperature of the mixture is between 0 and 20 ℃, and mixing the mixture and the polymer fibers in a mixer to ensure that the temperature reaches between 40 and 90 ℃ to obtain a bulk and sticky mixed mass;
s30, stirring and rotating the mixed mass material in a mixer to obtain uniform granular materials with the diameter of 1mm to 3 mm;
and S40, rolling the granular materials to form a membrane, and compounding the membrane with a current collector through rolling to obtain the pole piece.
2. A pole piece forming process with dry film as shown in claim 1, wherein: the material layer in the step S10 is a positive electrode material layer or a negative electrode material layer, and the main material of the positive electrode material layer comprises at least one of nickel-cobalt-manganese ternary material, lithium cobaltate, lithium iron phosphate, layered oxide and polyanion positive electrode material; the main material of the negative electrode material layer comprises at least one of graphite, silicon carbon, silicon oxygen and hard carbon.
3. A pole piece forming process with dry film as shown in claim 1, wherein: and step S10, mixing the main material of the material layer and the conductive agent in a mixer for 10-15 min, wherein the rotation speed of a rotor is not less than 1000rpm, and the temperature is controlled at 25-35 ℃.
4. A pole piece forming process with dry film as shown in claim 1, wherein: the rotor and bowl of the mixer are counter-rotated in step S10.
5. A pole piece forming process with dry film as shown in claim 1, wherein: in the step S20, the rotation speed of the rotor is kept at 1500-3750 rpm during mixing, and the mixing time is 10-20 min.
6. A pole piece forming process with dry film as shown in claim 1, wherein: in the step S30, the rotor and the rotary drum of the mixer rotate in the same direction, and the rotating speed of the rotor is 50 rpm-1000 rpm.
7. A pole piece forming process with dry film as shown in claim 1, wherein: the step S20 is followed by a step S21, wherein the step S21 is that the inner rotor of the mixing machine rotates at a speed of 50 rpm-500 rpm, so that the mixed mass is more compact.
8. A process for forming a sheet of material with dry film as claimed in claim 1, wherein the rolling and film compounding of the particulate material in step S40 is achieved by a method comprising the steps of:
s401, arranging at least two rotatable press rolls side by side at intervals, wherein the rotation directions of adjacent press rolls are opposite, and the adjacent press rolls have temperature difference and rotation speed difference;
s402, extending the granular materials from the intervals of the press rolls into the space between the adjacent press rolls, alternately shuttling the granular materials at the intervals of the plurality of press rolls, and forming a membrane by the rolling of the plurality of press rolls;
s403, after or during the process of rolling the granular material into the membrane, extending the current collector and the membrane into the interval between the same adjacent press rollers in the same direction, so that the membrane is compounded on the current collector to form a pole piece.
9. A pole piece forming process with dry film as shown in claim 8, wherein: when the number of the press rolls is three and the material layer main material is the positive electrode material layer main material, the three press rolls are a first press roll, a second press roll and a third press roll respectively, and the distance between the first press roll, the second press roll and the third press roll is set to be 0-2 mm; when the granular material forms a membrane firstly and then is compounded with the current collector, the roller temperature of the first press roller and the second press roller is set to be 60-250 ℃, the roller temperature of the third press roller is set to be 0-250 ℃, the granular material alternately shuttles through the interval parts of the first press roller, the second press roller and the third press roller to form the membrane and then is taken out, and then is compounded with the current collector through rolling between the press rollers.
10. A pole piece forming process with dry film as shown in claim 8, wherein: when the number of the press rolls is three and the material layer main material is the positive electrode material layer main material, the three press rolls are a first press roll, a second press roll and a third press roll respectively, and the distance between the first press roll, the second press roll and the third press roll is set to be 0-2 mm; when the granular material forms a membrane and the current collector is compounded to form a pole piece in the same step, the roller temperature of the first press roller and the second press roller is set to be 60-250 ℃, the roller temperature of the third press roller is set to be 0-200 ℃, the granular material is rolled at the interval of the first press roller and the second press roller to form the membrane, and the membrane and the current collector are extended into the second press roller and the third press roller to be compounded to form the pole piece in the same direction at the interval of the second press roller and the third press roller.
11. A pole piece forming process with dry film as shown in claim 8, wherein: when the number of the press rolls is three and the material layer main material is the negative electrode material layer main material, the three press rolls are a first press roll, a second press roll and a third press roll respectively, and the distance between the first press roll, the second press roll and the third press roll is set to be 0-2 mm; when the granular material forms a membrane firstly and then is compounded with the current collector, the roller temperature of the first press roller and the second press roller is set to be 60-250 ℃, the roller temperature of the third press roller is set to be 0-200 ℃, the granular material alternately shuttles through the interval parts of the first press roller, the second press roller and the third press roller to form the membrane and then is taken out, and then is compounded with the current collector through rolling between the press rollers.
12. A pole piece forming process with dry film as shown in claim 8, wherein: when the number of the press rolls is three and the material layer main material is the negative electrode material layer main material, the three press rolls are a first press roll, a second press roll and a third press roll respectively, and the distance between the first press roll, the second press roll and the third press roll is set to be 0-2 mm; when the granular material forms a membrane and the current collector is compounded to form a pole piece in the same step, the roller temperature of the first press roller and the second press roller is set to be 60-250 ℃, the roller temperature of the third press roller is set to be 0-200 ℃, the granular material is rolled at the interval of the first press roller and the second press roller to form the membrane, and the membrane and the current collector are extended into the second press roller and the third press roller to be compounded to form the pole piece in the same direction at the interval of the second press roller and the third press roller.
CN202310914052.9A 2023-07-24 2023-07-24 Pole piece forming process with dry-method diaphragm Pending CN116885109A (en)

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Application Number Priority Date Filing Date Title
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