CN116525770A - Dry electrode plate of sodium ion battery and preparation method thereof - Google Patents

Dry electrode plate of sodium ion battery and preparation method thereof Download PDF

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Publication number
CN116525770A
CN116525770A CN202310616804.3A CN202310616804A CN116525770A CN 116525770 A CN116525770 A CN 116525770A CN 202310616804 A CN202310616804 A CN 202310616804A CN 116525770 A CN116525770 A CN 116525770A
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Prior art keywords
electrode
ion battery
sodium ion
powder
plasticizer
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Inventor
陈以蒙
江柯成
蒋绮雯
王翔翔
董丰恺
司煜
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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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Priority to CN202310616804.3A priority Critical patent/CN116525770A/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • 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
    • 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
    • H01M4/622—Binders being polymers
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention relates to a dry electrode plate of a sodium ion battery and a preparation method thereof. The preparation method of the invention comprises the following steps: (1) Mixing the electrode active material, the conductive agent, the thermoplastic material and the plasticizer to obtain uniformly mixed dry powder, and processing the uniformly mixed dry powder by high-speed shearing to obtain fibrillated powder; (2) Extruding and molding the fibrillated powder to obtain an initial membrane; (3) Rolling the initial membrane to obtain an electrode membrane; (4) And carrying out hot rolling compounding on the electrode membrane and a current collector to obtain the dry electrode plate of the sodium ion battery. According to the invention, the dry electrode pole piece of the sodium ion battery is designed by changing the dosage and the molecular weight of the thermoplastic material and reasonably using the plasticizer, so that the flexibility of the pole piece is improved, and the cracking condition of the pole piece in the dry electrode preparation process is relieved.

Description

Dry electrode plate of sodium ion battery and preparation method thereof
Technical Field
The invention relates to the technical field of sodium ion batteries, in particular to a dry electrode plate of a sodium ion battery and a preparation method thereof.
Background
The dry electrode technology is that electrode active material, conductive agent and adhesive are mixed and stirred to obtain fibrous electrode powder, and then the fibrous electrode powder is formed by continuous rolling and is thermally compounded with a current collector to obtain the electrode plate. The method has the advantages of low production cost, high production efficiency, environmental friendliness and the like, and the preparation cost of the sodium ion battery can be obviously reduced by applying the dry electrode technology to the preparation process of the sodium ion battery. However, there are still some technical difficulties in the dry electrode preparation process, such as poor flexibility of the pole piece and cracking of the pole piece caused by hardness of the material, and these problems all need to be solved and optimized.
Disclosure of Invention
Therefore, the invention aims to solve the technical problems of poor flexibility, cracking of the pole piece and the like caused by material hardness in the prior art.
In order to solve the technical problems, the invention provides a preparation method of a dry electrode plate of a sodium ion battery. According to the invention, the dry electrode pole piece of the sodium ion battery is designed according to the consumption and the molecular weight of the thermoplastic material of the active material and the plasticizer, so that the flexibility of the pole piece is improved, and the cracking condition of the pole piece in the dry electrode preparation process is relieved.
The first aim of the invention is to provide a preparation method of a dry electrode slice of a sodium ion battery, which comprises the following steps:
(1) Mixing the electrode active material, the conductive agent, the thermoplastic material and the plasticizer to obtain uniformly mixed dry powder, and processing the uniformly mixed dry powder by high-speed shearing to obtain fibrillated powder; the molecular weight of the thermoplastic material is 1000 g/mol-10000 g/mol;
(2) Extruding and molding the fibrillated powder to obtain an initial membrane;
(3) Rolling the initial membrane to obtain an electrode membrane;
(4) And carrying out hot rolling compounding on the electrode membrane and a current collector to obtain the dry electrode plate of the sodium ion battery.
In one embodiment of the present invention, in the step (1), the electrode active material has a particle diameter D50 of 8 μm to 20 μm and a specific surface area of 0.5m 2 /g～10m 2 /g。
In one embodiment of the present invention, in step (1), the electrode active material includes a positive electrode active material or a negative electrode active material.
Further, the positive electrode active material includes, but is not limited to, one or more of three-dimensional porous vanadium sodium phosphate, iron sodium pyrophosphate, prussian blue, prussian white, sodium ion layered metal oxide.
Further, the positive electrode active material has a particle diameter D50 of D50=10μm to 20μm and a specific surface area S of 0.5m 2 /g～1.5m 2 /g。
Further, the negative active material includes, but is not limited to, hard carbon and/or soft carbon.
Further, the particle diameter D50 of the anode active material satisfies: d50 =8μm to 18 μm, the specific surface area S is 2m 2 /g～10m 2 /g。
In one embodiment of the present invention, in step (1), the electrode active material, the conductive agent, the thermoplastic material, and the plasticizer are used in amounts of: 85 to 97.5 weight percent, 0.5 to 5 weight percent of conductive agent, 0.5 to 5 weight percent of thermoplastic material powder and 0.1 to 5 weight percent of plasticizer.
In one embodiment of the present invention, in step (1), the thermoplastic material is selected from one or more of polyvinylidene fluoride (PVDF), acrylic resin (PAA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyetheretherketone (PEEK), polyether block amide (PEBA), polyurethane (TPU), and polyhexamethylene adipamide (PA 66).
In one embodiment of the present invention, in step (1), the plasticizer is dioctyl phthalate and/or isooctyl phthalate.
In one embodiment of the present invention, in the step (1), the stirring speed of the mixing is 100 r/min-300 r/min, the stirring time is 0.5 h-2 h, and the stirring temperature is normal temperature.
In one embodiment of the present invention, in the step (1), the high-speed shearing is performed by using a stirrer, the stirring speed is 4500 r/min-6000 r/min, the stirring time is 0.5 h-2 h, and the stirring temperature is 20 ℃ to 50 ℃.
In one embodiment of the present invention, in the step (2), the extrusion molding temperature is 40 ℃ to 120 ℃; the thickness of the initial membrane is 250-400 mu m.
In one embodiment of the present invention, in the step (3), the temperature of the rolling treatment is 80 ℃ to 150 ℃; the thickness of the electrode membrane is 120-200 mu m.
In one embodiment of the present invention, in step (4), the temperature of the hot roll compounding is 100 ℃ to 200 ℃.
In one embodiment of the present invention, in step (4), the current collector is selected from one or more of aluminum foil, carbon coated aluminum foil, metal mesh current collector, surface roughened aluminum foil, composite current collector. Further, a carbon-coated aluminum foil, a surface roughened aluminum foil or a metal mesh current collector is preferable.
Further, the specific treatment steps of the aluminum foil subjected to the surface roughening treatment are as follows: at least one side surface of the aluminum foil is contacted with alkali liquor for corrosion treatment, and then water and absolute ethyl alcohol are used for washing to remove surface residues.
Further, the alkali liquor is sodium hydroxide solution, and the concentration is 8-12 wt%.
Further, the corrosion treatment temperature is 40-50 ℃ and the time is 20-62 s.
In one embodiment of the present invention, in the step (4), the peel strength of the electrode sheet is 4.1N/m to 7.2N/m.
The second object of the invention is to provide a sodium ion battery dry electrode slice, which comprises the sodium ion battery dry electrode slice prepared by the preparation method.
Compared with the prior art, the technical scheme of the invention has the following advantages:
the invention designs the sodium ion battery dry electrode slice by using the dosage and molecular weight of the thermoplastic material and reasonably using the plasticizer. The thermoplastic material is fibrillated through high-speed shearing to form a cross net structure which is uniformly distributed on the electrode membrane; the thermoplastic material has a bonding effect, so that the contact area between the electrode membrane and the current collector is increased, and the peeling strength of the electrode pole piece is improved; meanwhile, the addition of the plasticizer improves the flexibility of the electrode sheet and relieves the condition that the dry electrode sheet is easy to crack; meanwhile, the stripping strength of the pole piece is further improved by virtue of the design of the molecular weight of the thermoplastic material.
In the preparation method provided by the invention, no toxic organic solvent is required to be added, pollution and residue are avoided, and an oven in the wet electrode coating process is also not required, so that the cost in the sodium ion battery preparation process is effectively reduced, and the method truly accords with the concepts of green and environment protection.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which,
FIG. 1 is a drawing of a pole piece scanning electron microscope prepared in example 4 of the present invention.
Detailed Description
In order to solve the technical problems of poor flexibility, cracking of the pole piece and the like caused by material hardness in the prior art, the invention provides the following technical scheme:
the first aim of the invention is to provide a preparation method of a dry electrode slice of a sodium ion battery, which comprises the following steps:
(1) Mixing the electrode active material, the conductive agent, the thermoplastic material and the plasticizer to obtain uniformly mixed dry powder, and uniformly dispersing the wetted dry powder by high-speed shearing to obtain fibrillated powder;
(2) Extruding the fibrillated powder to obtain an initial membrane;
(3) Rolling the initial membrane to obtain an electrode membrane;
(4) And (3) carrying out hot rolling compounding on the electrode membrane and a current collector to obtain the dry electrode plate of the sodium ion battery.
In a specific embodiment, in the step (1), the electrode active material has a particle diameter D50 of 8 μm to 20 μm and a specific surface area of 0.5 to 10m 2 /g。
Further, the electrode active material includes a positive electrode active material or a negative electrode active material.
The positive electrode active material includes, but is not limited to, three-dimensional porous sodium vanadium phosphate, sodium iron pyrophosphate, prussian blue, prussian white, and layered metal oxide Na x Ni i Fe j Mn k M m O 2 One or more of (a) and (b).
Further, the layered metal oxide satisfies: 0<i.ltoreq.0.4, 0< j.ltoreq.0.5, 0< k.ltoreq.0.6, 0< m.ltoreq.0.2, i+j+k+m=1.
Further, when x is 0.6< 0.8 or less, the material is a layered oxide of P2 phase; when x is less than or equal to 0.8 and less than or equal to 1, the material is a layered oxide of O3 phase.
In a specific embodiment, the particle diameter D50 of the positive electrode active material satisfies d50=10 μm to 20 μm, and the specific surface area S satisfies s=0.5 m 2 /g～1.5m 2 /g。
In particular embodiments, the negative electrode material includes, but is not limited to, hard carbon and/or soft carbon.
Further, the particle diameter D50 of the anode active material satisfies: d50 =8 μm to 18 μm, the specific surface area S satisfies: s=2m 2 /g～10m 2 /g。
In a specific embodiment, the conductive agent is one or more of SuperP, ketjen black, carbon nanotubes, carbon nanofibers, graphene, conductive carbon, preferably carbon nanotubes and/or carbon nanofibers.
In a specific embodiment, in step (1), the amounts of the electrode active material, the conductive agent, the thermoplastic material, and the plasticizer are: 85 to 97.5 weight percent, 0.5 to 5 weight percent of conductive agent, 0.5 to 5 weight percent of thermoplastic material powder and 0.1 to 5 weight percent of plasticizer.
In specific embodiments, in step (1), the thermoplastic material is selected from one or more of polyvinylidene fluoride (PVDF), acrylic resin (PAA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyetheretherketone (PEEK), polyether block amide (PEBA), polyurethane (TPU), and polyhexamethylene adipamide (PA 66).
In a specific embodiment, in step (1), the molecular weight of the thermoplastic material is from 1000g/mol to 10000g/mol. Can be 1000 g/mol-5000 g/mol,5000 g/mol-8000 g/mol,8000 g/mol-10000 g/mol. For example 1000g/mol, 2000g/mol, 3000g/mol, 4000g/mol, 5000g/mol, 6000g/mol, 7000g/mol, 8000g/mol, 9000g/mol, 10000g/mol etc., or any value in between any two values.
In a specific embodiment, in step (1), the plasticizer is dioctyl phthalate and/or isooctyl phthalate.
In a specific embodiment, in the step (1), the stirring speed of the mixing is 100 r/min-300 r/min, the stirring time is 0.5 h-2 h, and the stirring temperature is normal temperature.
In a specific embodiment, in the step (1), the high-speed shearing is performed by using a stirrer, the stirring speed is 4500 r/min-6000 r/min, the stirring time is 0.5 h-2 h, and the stirring temperature is 20-50 ℃. When the rotating speed is lower than 4500r/min, the rotating speed is lower, the requirement of fibrosis cannot be met, the thermoplastic material is difficult to form a cross net structure, the thermoplastic material cannot be uniformly contacted with the active material, the conductive agent and the plasticizer, and the performance of the pole piece is affected.
In a specific embodiment, in the step (2), the extrusion molding temperature is 40-120 ℃; the thickness of the initial membrane is 250-400 mu m.
In a specific embodiment, in the step (3), the temperature of the rolling treatment is 80-150 ℃; the thickness of the electrode membrane is 120-200 mu m.
In a specific embodiment, in the step (4), the temperature of the hot rolling compounding is 100-200 ℃.
In a specific embodiment, in the step (4), the current collector is one or more selected from aluminum foil, carbon coated aluminum foil, metal mesh current collector, aluminum foil with roughened surface, and composite current collector. Further, a carbon-coated aluminum foil, a surface roughened aluminum foil or a metal mesh current collector is preferable.
Further, the specific treatment steps of the aluminum foil subjected to the surface roughening treatment are as follows: at least one side surface of the aluminum foil is contacted with alkali liquor for corrosion treatment, and then water and absolute ethyl alcohol are used for washing to remove surface residues.
Further, the alkali liquor is sodium hydroxide solution, and the concentration is 8-12 wt%. Further, the corrosion treatment temperature is 40-50 ℃ and the time is 20-62 s.
In one embodiment of the present invention, in the step (4), the peel strength of the electrode sheet is 4.1N/m to 7.2N/m.
The second object of the invention is to provide a sodium ion battery dry electrode slice, which comprises the sodium ion battery dry electrode slice prepared by the preparation method.
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
Example 1
The embodiment provides a preparation method of a dry electrode slice, and the electrode slice can be used as a positive electrode of a sodium ion battery. The preparation method comprises the following steps:
1. particle diameter D50 of 14.8 μm and specific surface area S of 1.2m 2 Mixing/g sodium-electricity positive electrode material, a conductive agent, thermoplastic material powder polytetrafluoroethylene (PTFE, with the molecular weight of 1000 g/mol) and plasticizer dioctyl phthalate according to the mass percentage of 85%, 5% and 5% in a stirring tank at the speed of 200r/min to obtain uniformly mixed dry powder; then fully mixing at the stirring speed of 2000 r/min; most preferably, the first to fourthAnd then controlling the stirring temperature at 55 ℃, adjusting the stirring speed to 5500r/min, and uniformly dispersing the sodium-electricity positive electrode material, the conductive agent, the thermoplastic material powder and the plasticizer through high-speed shearing force generated by high-strength stirring to achieve the fibrosis effect and obtain the fibrosis powder.
2. Extruding the fibrillated powder material in an extruder at 80 ℃ to obtain a sheet with the thickness of 350 mu m; rolling the obtained sheet at 120 ℃ to form a 180 μm thick pole piece film; and finally, carrying out hot rolling compounding on the positive electrode sheet film and the aluminum foil current collector subjected to surface roughening treatment at 150 ℃ to obtain the positive electrode sheet of the sodium ion battery dry electrode.
Example 2
The embodiment provides a preparation method of a dry electrode slice, and the electrode slice is used as the positive electrode of a sodium ion battery. The method comprises the following steps:
the preparation procedure is similar to example 1, except that: the positive electrode plate of the sodium ion battery dry electrode is prepared from the following components in percentage by mass, wherein the positive electrode material, the conductive agent, polytetrafluoroethylene (PTFE) and the plasticizer dioctyl phthalate are 97.5%, 0.5%, 1% and 1% respectively.
Example 3
The embodiment provides a preparation method of a dry electrode slice, and the electrode slice is used as the positive electrode of a sodium ion battery. The method comprises the following steps:
the preparation procedure is similar to example 2, except that: the molecular weight of Polytetrafluoroethylene (PTFE) was 10000g/mol.
Example 4
The embodiment provides a preparation method of a dry electrode slice, and the electrode slice is used as the positive electrode of a sodium ion battery. The method comprises the following steps:
the preparation procedure is as in example 1, with the following differences: the positive electrode plate of the dry electrode of the sodium ion battery is prepared from the following materials of 95.5 percent by mass, 2.5 percent by mass, 1.9 percent by mass and 0.1 percent by mass of positive electrode materials, conductive agents, thermoplastic materials of Polytetrafluoroethylene (PTFE) and plasticizer of dioctyl phthalate. The dry electrode sheet obtained was characterized and the results are shown in fig. 1. As can be seen from fig. 1, the material is fibrillated, forming a cross-web structure.
Example 5
The embodiment provides a preparation method of a dry electrode slice, and the electrode slice is used as the positive electrode of a sodium ion battery. The preparation method comprises the following steps:
1. particle diameter D50 of 13.6 μm and specific surface area S of 1.35m 2 Mixing/g of sodium-electricity positive electrode material, a conductive agent, polytetrafluoroethylene (PTFE, with the molecular weight of 1000 g/mol) and plasticizer isooctyl phthalate according to the mass percentages of 85%, 5% and 5% in a stirring tank at the speed of 200r/min to obtain uniformly mixed dry powder; then fully mixing at the stirring speed of 2000 r/min; finally, the stirring temperature is controlled at 55 ℃, the stirring speed is regulated to 5500r/min, and the sodium-electricity positive electrode material, the conductive agent, the thermoplastic material powder and the plasticizer are uniformly dispersed through high-speed shearing force generated by high-strength stirring, so that the fiberization effect is achieved, and the fiberized powder is obtained.
2. Extruding the fibrillated powder material in an extruder at 80 ℃ to obtain a sheet with the thickness of 350 mu m; rolling the obtained sheet at 120 ℃ to form a 180 μm thick pole piece film; and finally, carrying out hot rolling compounding on the positive electrode sheet film and the aluminum foil current collector subjected to surface roughening treatment at 150 ℃ to obtain the positive electrode sheet of the sodium ion battery dry electrode.
Example 6
The embodiment provides a preparation method of a dry electrode slice, which can be used as a negative electrode of a sodium ion battery. The preparation method comprises the following steps:
1. the particle diameter D50 is 9.3 mu m, and the specific surface area S is 4.5m 2 Mixing/g of sodium-electricity negative electrode material, a conductive agent, polytetrafluoroethylene (PTFE, with molecular weight of 8000 g/mol) and plasticizer isooctyl phthalate according to mass percent of 85%, 5% and 5% in a stirring tank at a speed of 200r/min to obtain uniformly mixed dry powder; then fully mixing at the stirring speed of 2000 r/min; finally, the stirring temperature is controlled at 55 ℃, the stirring speed is regulated at 5500r/min, and the sodium-electricity negative electrode material, the conductive agent, the thermoplastic material powder and the plasticization are enabled by high-speed shearing force generated by high-strength stirringThe agent is uniformly dispersed to achieve the fiberization effect, and the fiberized powder is obtained.
2. Extruding the fibrillated powder material in an extruder at 80 ℃ to obtain a sheet with the thickness of 300 mu m; rolling the obtained sheet at 120 ℃ to form a pole piece film with the thickness of 120 mu m; and finally, carrying out hot rolling compounding on the negative electrode piece film and the aluminum foil current collector subjected to surface roughening treatment at 130 ℃ to obtain the sodium ion battery dry electrode negative electrode piece.
Example 7
The embodiment provides a preparation method of a dry electrode slice, which can be used as a negative electrode of a sodium ion battery. The preparation method comprises the following steps:
the preparation procedure is as in example 6, with the following differences: the components of the preparation materials of the negative electrode plate of the dry electrode of the sodium ion battery are different in mass percentage, and the negative electrode material, the conductive agent, polytetrafluoroethylene (PTFE, molecular weight is 8000 g/mol) and the plasticizer isooctyl phthalate are 95.5%, 1.5%, 2.5% and 0.5% respectively.
Example 8
The embodiment provides a preparation method of a dry electrode slice, which can be used as a negative electrode of a sodium ion battery. The preparation method comprises the following steps:
the preparation procedure is as in example 6, with the following differences: the components of the preparation materials of the negative electrode plate of the dry electrode of the sodium ion battery are different, and the mass percentages of the negative electrode material, the conductive agent, polytetrafluoroethylene (PTFE, molecular weight is 8000 g/mol) and the plasticizer isooctyl phthalate are respectively 90%, 1.5%, 4.5% and 4%.
Comparative example 1
The comparative example provides a method for preparing a dry electrode positive electrode plate of a sodium ion battery, which is different from example 1 in that the molecular weight of the thermoplastic powder is regulated to be 100g/mol. Specifically, the preparation method comprises the following steps:
1. particle diameter D50 of 14.8 μm and specific surface area S of 1.2m 2 Per gram of sodium-electricity positive electrode material, a conductive agent, polytetrafluoroethylene (PTFE, molecular weight of 100 g/mol) and plasticizer isooctyl phthalate according to mass percent of 97.5%, 0.5%, 1% and 1% of the raw materials are placed in a stirring tank to be mixed at the speed of 200r/min, and uniformly mixed dry powder is obtained; then fully mixing at the stirring speed of 2000 r/min; finally, the stirring temperature is controlled at 55 ℃, the stirring speed is regulated to 5500r/min, and the high-speed shearing force generated by high-strength stirring is used for uniformly dispersing the powder of the sexual material, the conductive agent and the thermoplastic material, so as to achieve the fiberization effect and obtain the fiberized powder.
2. Extruding the fibrillated powder material in an extruder at 80 ℃ to obtain a sheet with the thickness of 350 mu m; rolling the obtained sheet at 120 ℃ to form a 180 μm thick pole piece film; and finally, carrying out hot rolling compounding on the positive electrode sheet film and the aluminum foil current collector subjected to surface roughening treatment at 150 ℃ to obtain the positive electrode sheet of the sodium ion battery dry electrode.
Comparative example 2
The comparative example provides a method for preparing a dry electrode positive plate of a sodium ion battery, and the main difference from the embodiment is that no plasticizer is added in the comparative example. Specifically, the preparation method comprises the following steps:
1. particle diameter D50 of 15.8 μm and specific surface area S of 1.47m 2 Mixing/g sodium-electricity positive electrode material, a conductive agent and polytetrafluoroethylene (PTFE, with molecular weight of 8000 g/mol) according to 90%, 5% and 5% of mass percentages in a stirring tank at a speed of 200r/min, and fully mixing at a stirring speed of 2000 r/min; finally, the stirring temperature is controlled at 55 ℃, the stirring speed is regulated to 5500r/min, and the high-speed shearing force generated by high-strength stirring is used for uniformly dispersing the powder of the sexual material, the conductive agent and the thermoplastic material, so as to achieve the fiberization effect and obtain the fiberized powder.
2. Extruding the fibrillated powder material in an extruder at 80 ℃ to obtain a sheet with the thickness of 350 mu m; rolling the obtained sheet at 120 ℃ to form a 180 μm thick pole piece film; and finally, carrying out hot rolling compounding on the positive electrode sheet film and the aluminum foil current collector subjected to surface roughening treatment at 150 ℃ to obtain the positive electrode sheet of the sodium ion battery dry electrode.
Comparative example 3
The comparative example provides a method for preparing a positive electrode plate of a sodium ion battery, which is different from example 4 in that the molecular weight of the thermoplastic powder is regulated to 15000g/mol. Specifically, the preparation method comprises the following steps:
1. mixing sodium-electricity positive electrode material with the particle diameter D50 of 14.3 mu m and the specific surface area S of 1.2, a conductive agent, polytetrafluoroethylene (PTFE, the molecular weight of which is 15000 g/mol) and dioctyl phthalate serving as a plasticizer respectively with the mass percentages of 95.5%, 2.5%, 1.9% and 0.1% in a stirring tank at the speed of 200r/min to obtain uniformly mixed dry powder; then fully mixing at the stirring speed of 2000 r/min; finally, the stirring temperature is controlled at 55 ℃, the stirring speed is regulated to 5500r/min, and the high-speed shearing force generated by high-strength stirring is used for uniformly dispersing the powder of the sexual material, the conductive agent and the thermoplastic material, so as to achieve the fiberization effect and obtain the fiberized powder.
2. Extruding the fibrillated powder material in an extruder at 80 ℃ to obtain a sheet with the thickness of 350 mu m; rolling the obtained sheet at 120 ℃ to form a 180 μm thick pole piece film; and finally, carrying out hot rolling compounding on the positive electrode sheet film and the aluminum foil current collector at 150 ℃ to obtain the positive electrode sheet of the sodium ion battery dry electrode.
Comparative example 4
This comparative example provides a method for preparing a negative electrode tab of a sodium ion battery, which is different from example 8 in that no plasticizer is added. Specifically, the preparation method comprises the following steps:
1. the particle diameter D50 is 9.3 mu m, and the specific surface area S is 4.5m 2 The sodium-electricity cathode material per gram, the conductive agent and polytetrafluoroethylene (PTFE, the molecular weight of which is 8000 g/mol) are mixed in a stirring tank according to the mass percentage of 90%, 5% and 5% at the speed of 200r/min to obtain uniformly mixed dry powder; then fully mixing at the stirring speed of 2000 r/min; finally, the stirring temperature is controlled at 55 ℃, the stirring speed is regulated to 5500r/min, and the sodium-electricity negative electrode material, the conductive agent and the thermoplastic material powder are uniformly dispersed through high-speed shearing force generated by high-strength stirring, so that the fiberization effect is achieved, and the fiberized powder is obtained.
2. Extruding the fibrillated powder material in an extruder at 80 ℃ to obtain a sheet with the thickness of 350 mu m; rolling the obtained sheet at 120 ℃ to form a 180 μm thick pole piece film; and finally, carrying out hot rolling compounding on the negative electrode plate film and the aluminum foil current collector at 150 ℃ to obtain the sodium ion battery dry electrode negative electrode plate.
The raw material types and the amounts of the above examples and comparative examples are shown in Table 1, and are as follows:
TABLE 1
Performance testing
The pole pieces obtained in examples 1 to 8 and comparative examples 1 to 4 were subjected to performance test of peel strength and flexibility.
Peel strength test method: the positive and negative electrode sheets prepared in examples 1 to 8 and comparative examples 1 to 4 were subjected to peel strength test according to GB/T2792-1998 standard. The method comprises the steps of placing an adhesive tape and a material to be bonded (namely a material to be tested) under the conditions of a room temperature of 23+/-2 ℃ and a relative humidity of 65+/-5% for more than 2 hours, peeling the adhesive tape, cutting off 3-5 layers outside, uniformly peeling the adhesive tape, bonding the adhesive tape and one end of the material to be bonded, placing a polyester film with the length of about 200mm and the width of 40mm below the other end of the material to be bonded, rolling the sample back and forth for 3 times at the speed of about 120mm/s under the self weight by using a wheel of a rolling device, folding the free end of the sample by 180 ° (positive electrode of 90 degrees and negative electrode of 180 degrees), peeling off the bonding surface by about 10mm, clamping the material to be bonded on a lower clamp, and clamping the free end of the sample on the upper clamp. The stripping surface is kept consistent with the tester force line. The tester continuously peeled at a falling rate of 300.+ -.10 mm/min. The effective peel adhesion length was about 100mm and there were automated technical means to give peel strength and peel force data.
The flexibility test method comprises the following steps: cutting the pole piece into pieces with the width of 50mm and the length of 200mm, winding the cut pole piece 360 degrees by steel needles with different diameters, and observing whether the pole piece has cracks or not and the light transmission phenomenon. After the pole piece is wound around the steel needle, no crack and light transmission phenomenon occur, and the flexibility is qualified; the smaller the diameter of the steel needle through which the pole piece can pass, the better the flexibility of the pole piece.
Table 2 the film sheets of examples 1 to 8 and comparative examples 1 to 4 were extrusion-molded, sheet peel strength, and flexibility
As can be seen from table 2, examples 1 to 5 and examples 6 to 8 are respectively the extrusion molding state of the positive electrode and the negative electrode films of the sodium ion battery and the peel strength of the pole piece; by adopting the dry electrode preparation method provided by the invention, the positive and negative electrode membrane with good extrusion molding state and the positive and negative electrode pole piece with higher peeling strength are obtained.
Compared with example 2, the difference is that the molecular weight of the thermoplastic material is different, the molecular weight of the plasticizer in comparative example 1 is 100g/mol (less than 1000 g/mol), the peeling strength of the obtained membrane is far lower than that in example 1, and the edge and center cracking of the membrane is more serious, which indicates that the peeling strength of the material can be effectively improved by regulating the molecular weight of the plastic material, and the cracking condition of the membrane is solved.
Compared with the example, the comparative example 2 has other parameters within the range of the invention, and the difference is that the edge of the membrane obtained in the comparative example 2 is seriously cracked and has poorer flexibility without adding the plasticizer, which indicates that the addition of the plasticizer is beneficial to improving the flexibility of the dry electrode sheet.
Comparative example 3 is different from example 4 in that comparative example 3 uses PTFE (more than 10000 g/mol) having a larger molecular weight of a thermoplastic material, and the material having an excessive molecular weight is difficult to disperse and poor in processability, and the prepared slurry is not uniformly fibrillated and has a problem of unstable adhesion after being thermally compounded into a dry electrode sheet, which means that the molecular weight of the thermoplastic material needs to be within a proper range to obtain a dry electrode sheet excellent in performance.
Comparative example 4 is different from example 8 in that the addition of the plasticizer is not added to the comparative example 4, resulting in poor flexibility of the sheet and severe cracking of the edge of the sheet, and it is explained again that the addition of the plasticizer is advantageous to improve flexibility of the dry electrode sheet and reduce cracking of the sheet.
In a word, the invention can effectively improve the flexibility and the peeling strength of the dry electrode pole piece and solve the problem of pole piece cracking by using the dosage and the molecular weight of the thermoplastic material of the positive electrode material and reasonably using the plasticizer.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications of the present invention will be apparent to those of ordinary skill in the art in light of the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present invention.

Claims (10)

1. The preparation method of the sodium ion battery dry electrode slice is characterized by comprising the following steps of:
(1) Mixing the electrode active material, the conductive agent, the thermoplastic material and the plasticizer to obtain uniformly mixed dry powder, and processing the uniformly mixed dry powder by high-speed shearing to obtain fibrillated powder; the molecular weight of the thermoplastic material is 1000 g/mol-10000 g/mol;
(2) Extruding and molding the fibrillated powder to obtain an initial membrane;
(3) Rolling the initial membrane to obtain an electrode membrane;
(4) And carrying out hot rolling compounding on the electrode membrane and a current collector to obtain the dry electrode plate of the sodium ion battery.
2. The method according to claim 1, wherein in the step (1), the electrode active material has a particle diameter D50 of 8 μm to 20 μm and a specific surface area of 0.5m 2 /g～10m 2 /g。
3. The method of claim 1, wherein in step (1), the thermoplastic material is selected from one or more of polyvinylidene fluoride, acrylic resin, polytetrafluoroethylene, styrene-butadiene rubber, polyetheretherketone, polyether block amide, polyurethane, and polyhexamethylene adipamide; the plasticizer is dioctyl phthalate and/or isooctyl phthalate.
4. The method according to claim 1, wherein in the step (1), the electrode active material, the conductive agent, the thermoplastic material and the plasticizer are used in amounts of: 85 to 97.5 weight percent, 0.5 to 5 weight percent of conductive agent, 0.5 to 5 weight percent of thermoplastic material powder and 0.1 to 5 weight percent of plasticizer.
5. The method of manufacturing according to claim 1, wherein the current collector is selected from one or more of aluminum foil, carbon coated aluminum foil, metal mesh current collector, surface roughened aluminum foil, composite current collector.
6. The process according to claim 1, wherein in step (1),
the stirring speed of the mixing is 100 r/min-300 r/min, and the stirring time is 0.5 h-2 h;
the high-speed shearing is carried out by adopting a stirrer, the stirring speed is 4500 r/min-6000 r/min, the stirring time is 0.5 h-2 h, and the stirring temperature is 20-50 ℃.
7. The method according to claim 1, wherein in the step (2), the extrusion molding temperature is 40 to 120 ℃; the thickness of the initial membrane is 250-400 mu m.
8. The method according to claim 1, wherein in the step (3), the temperature of the rolling treatment is 80 to 150 ℃; the thickness of the electrode membrane is 120-200 mu m.
9. The method according to claim 1, wherein in the step (4), the temperature of the hot rolling compounding is 100 ℃ to 200 ℃; the stripping strength of the electrode plate is 4.1N/m-7.2N/m.
10. A sodium ion battery dry electrode slice prepared by the preparation method of any one of claims 1 to 9.
CN202310616804.3A 2023-05-29 2023-05-29 Dry electrode plate of sodium ion battery and preparation method thereof Pending CN116525770A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117219888A (en) * 2023-10-07 2023-12-12 蚌埠学院 Novel dry thick film electrode plate-based aqueous sodium ion secondary battery and preparation method thereof
CN117253990A (en) * 2023-10-11 2023-12-19 中国石油大学(华东) Method for preparing sodium ion battery dry method negative electrode plate

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117219888A (en) * 2023-10-07 2023-12-12 蚌埠学院 Novel dry thick film electrode plate-based aqueous sodium ion secondary battery and preparation method thereof
CN117253990A (en) * 2023-10-11 2023-12-19 中国石油大学(华东) Method for preparing sodium ion battery dry method negative electrode plate

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