CN113690543A - Integrated pole piece and preparation method thereof, secondary battery and battery module - Google Patents

Integrated pole piece and preparation method thereof, secondary battery and battery module Download PDF

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CN113690543A
CN113690543A CN202110781741.8A CN202110781741A CN113690543A CN 113690543 A CN113690543 A CN 113690543A CN 202110781741 A CN202110781741 A CN 202110781741A CN 113690543 A CN113690543 A CN 113690543A
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pole piece
preparation
integrated pole
diaphragm
integrated
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符宽
赖旭伦
孙先维
陈杰
杨山
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Huizhou Liwei Electronic Technology Co ltd
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Huizhou Liwei Electronic Technology Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H01M50/434—Ceramics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • 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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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Inorganic Chemistry (AREA)
  • Composite Materials (AREA)
  • Ceramic Engineering (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention belongs to the technical field of secondary batteries, and particularly relates to an integrated pole piece and a preparation method thereof, a secondary battery and a battery module, which comprise a pole piece; and the diaphragm slurry layer is arranged on at least one side surface of the pole piece and comprises ceramic powder and a polyethylene oxide and polyacrylic acid complex. The integrated pole piece has good wettability and liquid retention for electrolyte, high-temperature heat resistance, capability of avoiding the risk of high-temperature hole breakage of the diaphragm, capability of avoiding contact short circuit of a positive electrode and a negative electrode and good safety.

Description

Integrated pole piece and preparation method thereof, secondary battery and battery module
Technical Field
The invention belongs to the technical field of batteries, and particularly relates to an integrated pole piece, a preparation method of the integrated pole piece, a secondary battery and a battery module.
Background
Currently, commercially used separators are ceramic-coated polyolefin separators. The polyolefin diaphragm has the advantages of light and thin film formation and good flexibility, but the polyolefin diaphragm has high crystallinity, low surface energy and small polarity, has poor affinity, wettability and liquid retention with electrolyte, has poor contact with the surfaces of positive and negative pole pieces, and is easy to cause the increase of the internal resistance of a secondary battery. Although the wettability and the heat resistance of the coated ceramic layer to the electrolyte are improved, when the temperature reaches above 130 ℃, the polyolefin diaphragm can generate a hole breaking risk, so that the short circuit of a positive electrode and a negative electrode is caused, the spontaneous combustion of the battery cell is caused, and potential safety hazards exist.
Disclosure of Invention
One of the objects of the present invention is: aiming at the defects of the prior art, the integrated pole piece is provided, has good wettability and liquid retention to electrolyte, has high-temperature heat resistance, avoids the risk of high-temperature hole breakage of the diaphragm, can avoid the contact short circuit of a positive pole and a negative pole, and has good safety.
In order to achieve the purpose, the invention adopts the following technical scheme:
an integrated pole piece comprises a pole piece and a diaphragm slurry layer arranged on at least one side face of the pole piece, wherein the diaphragm slurry layer comprises ceramic powder and a polyoxyethylene and polyacrylic acid complex.
As an improvement of the integrated pole piece, the thickness of the diaphragm slurry layer is 3-8 um.
The second purpose of the invention is: aiming at the defects of the prior art, the preparation method of the integrated pole piece is provided, and the preparation method is simple, good in controllability, easy to operate and capable of realizing mass production.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of an integrated pole piece comprises the following steps:
step (A): adding polyoxyethylene and polyacrylic acid into a solvent, mixing and stirring to form a complex solution;
step (B): mixing the complex solution and the ceramic powder in the step (A) to obtain coating slurry;
step (C): and (C) coating and drying the coating slurry in the step (B) on at least one surface of the pole piece to form a diaphragm slurry layer.
As an improvement of the preparation method of the integrated pole piece, the weight parts of the polyoxyethylene and the polyacrylic acid in the step (A) are 1-3: 0.5-1.
As an improvement of the preparation method of the integrated pole piece, the molecular weight of the polyoxyethylene is 600-800 ten thousand.
As an improvement of the preparation method of the integrated pole piece, the preparation method also comprises a wetting agent and an adhesive, and the coating slurry is prepared by mixing the complex solution and the wetting agent in the step (A), then adding the ceramic powder and the adhesive, and stirring and mixing.
As an improvement of the preparation method of the integrated pole piece, the weight parts of the ceramic powder, the complex solution, the binder and the wetting agent are 80-90: 8-12: 0.5-2: 3-6.
As an improvement of the preparation method of the integrated pole piece, the solid content of the coating slurry in the step (B) is 35-55%.
Wherein the dispersing wetting agent is an organic silicon dispersing wetting agent or an ether dispersing wetting agent.
Wherein, the ceramic powder is one or a mixture of more than one of alumina, zirconia, boehmite and aluminum hydroxide.
The third purpose of the invention is that: the secondary battery is provided aiming at the defects of the prior art, and the pole piece has good wettability and liquid retention to electrolyte, high temperature resistance, good safety, difficult short circuit and long service life.
In order to achieve the purpose, the invention adopts the following technical scheme:
a secondary battery comprises a positive electrode, a negative electrode, electrolyte and a shell, wherein the positive electrode and/or the negative electrode are/is the integrated pole piece.
The fourth purpose of the invention is that: aiming at the defects of the prior art, the battery module is good in safety performance, high in capacity and long in service life.
In order to achieve the purpose, the invention adopts the following technical scheme:
a battery module includes a plurality of electrically connected secondary batteries.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention sets the diaphragm slurry layer on the surface of the pole piece to replace the traditional diaphragm, greatly reduces the battery volume, improves the energy density, uses the diaphragm slurry layer formed by blending the ceramic powder and the PEO-PAA complex compound to have good wettability and liquid retention to the electrolyte, and the diaphragm slurry layer has high temperature heat resistance, still has no hair damage at 200 ℃, has good heat resistance, solves the problem of high temperature diaphragm broken hole short circuit, and has good safety and long service life.
2. The traditional diaphragm comprises a base film and a coating, the thickness of the traditional diaphragm is 8-15um, and the thickness of the traditional diaphragm is thicker, but the invention directly coats a layer of coating diaphragm on a pole piece, so that the thickness of the diaphragm is effectively reduced, and the capacity of a battery cell is increased.
3. The PEO-PAA complex in the diaphragm slurry has good electrophilic electrolyte performance, can absorb electrolyte to form tiny gel particles, and has good liquid retention capacity.
4. The traditional PP/PE base film is easy to have broken holes at the temperature of about 150 ℃, and the integrated pole piece has good thermal stability and can resist the high temperature of 200 ℃.
5. The invention can remove the traditional PP/PE basal membrane and save the production cost.
Drawings
Fig. 1 is a diagram of a lithium ion conduction mechanism of the PEO-based solid electrolyte of the present invention.
FIG. 2 is a schematic flow chart of the process of coating the separator slurry of the present invention on the surface of a pole piece.
Fig. 3 is a graph comparing drip diffusion of a conventional coated membrane with an integrated pole piece of the present invention.
FIG. 4 is a graph showing the results of a 200 ℃ high temperature test of a battery prepared from the integrated electrode plate of the present invention.
Fig. 5 is a graph showing the results of a high temperature test at 200 c performed on a battery fabricated using an organic separator according to the prior art.
FIG. 6 is a schematic structural diagram of an integrated pole piece of the present invention.
FIG. 7 is another schematic structural diagram of the integrated pole piece of the present invention.
Wherein: 1. pole pieces; 2. a separator slurry layer.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and the accompanying drawings, but the embodiments of the invention are not limited thereto.
1. An integrated pole piece comprises a pole piece 1 and a diaphragm slurry layer 2 arranged on at least one side face of the pole piece 1, wherein the diaphragm slurry layer 2 comprises ceramic powder and a polyoxyethylene and polyacrylic acid complex.
The integrated pole piece has good wettability and liquid retention for electrolyte, high-temperature heat resistance, capability of avoiding the risk of high-temperature hole breakage of the diaphragm, capability of avoiding contact short circuit of a positive electrode and a negative electrode and good safety.
The invention mainly coats a ceramic + PEO-PAA complex blending layer directly on the surface of the pole piece, wherein the PEO-PAA complex has good film-forming property and forms the coated ceramic layer into a whole, thereby preventing large gaps and avoiding the risk of short circuit of the anode and the cathode. The ceramic layer is coated alone, the ceramic layer has poor flexibility and is easy to crack and fall off, the addition of the PEO-PAA complex enables the PEO-PAA complex to form a whole body, the flexibility of the coating and the integrity of the coating can be greatly improved, as shown in figures 6 and 7, after the integrated pole piece is bent, the diaphragm slurry layer still becomes a whole body and is very flexible without cracks.
PEO is a solid electrolyte and has the advantages of low price, simple synthesis, strong dissociation capability of lithium salt and good compatibility with lithium metal. The lithium salt can be dissolved by the PEO polymer segments to form free Li ions. These Li ions can become mobile by segmental motion of PEO, thereby realizing conduction of Li ions in the PEO-based solid electrolyte, the principle of which is shown in fig. 1. PEO has a molecular structure of (CH)2CH2O) is represented by the following formula (1).
Figure BDA0003155421230000041
PEO has an unshared electron pair of ether oxygen and strong affinity for hydrogen bonds, and can form complexes with many organic low-molecular compounds, polymers and some inorganic electrolytes. Organic compounds that can form complexes with PEO are polyacrylic acid, polymethacrylic acid, maleic anhydride-acrylic acid copolymers, catechol tannins, alpha-naphthols, tris (hydroxymethyl) phenols, phenolic resins, urea, D-thiourea, and punchwood, among others. Inorganic substances that can form complexes with PEO are amine fluoride, sodium fluoride, bromine, iodine, potassium, mercury halides, ammonium thiocyanate, potassium thiocyanate, and the like.
Polyacrylic acid (PAA) is a water-soluble high-molecular polymer, also known as acrylic acid homopolymer, having the chemical formula [ C3H4O2]n has a structural formula shown as the following formula (2), is weakly acidic, is a white solid, and is commonly used as a binder in the lithium battery industry.
Figure BDA0003155421230000051
Herein, PEO is subjected to a blending reaction with a PAA solution to form a PEO-PAA complex having a structural formula shown in the following formula (3), wherein PEO: PAA is 1:0.6 (mass fraction ratio), and the reason for this blending ratio is that PEO swells in the electrolyte to dissolve, and if the PEO ratio is too high to inject, the integrity of the separator is affected. However, strong hydrogen bonding force exists between PEO and PAA, and if the content of PAA is too high, individual PEO-PAA agglomerated particles are formed in the slurry, which affects the coating process and the surface uniformity of the separator. Therefore, the PEO: the PAA blending ratio is selected to be 1: 0.6.
Figure BDA0003155421230000052
Figure BDA0003155421230000061
preferably, the thickness of the diaphragm slurry layer 2 is 3-8 um. Preferably, the thickness of the separator paste layer 2 is 6 um.
2. A preparation method of an integrated pole piece comprises the following steps:
step (A): adding polyoxyethylene and polyacrylic acid into a solvent, mixing and stirring to form a complex solution;
step (B): mixing the complex solution and the ceramic powder in the step (A) to obtain coating slurry;
step (C): and (C) coating and drying the coating slurry in the step (B) on at least one surface of the pole piece 1 to form a diaphragm slurry layer 2, wherein the process is shown in figure 2.
The preparation method of the integrated pole piece is simple, good in controllability, easy to operate and capable of realizing mass production. The prepared integrated pole piece has a flat surface without cracks as shown in figure 6, has good flexibility, and is smooth and without cracks when being bent as shown in figure 7, and is suitable for a roll core battery and a laminated battery.
Preferably, the weight parts of the polyoxyethylene and the polyacrylic acid in the step (A) are 1-3: 0.5-1. Preferably, the weight parts of the polyoxyethylene and the polyacrylic acid in the step (A) are 1-2: 0.5-0.8. More preferably, the weight parts of the polyethylene oxide and the polyacrylic acid in the step (A) are 1: 0.6.
Preferably, the molecular weight of the polyoxyethylene is 600-800 ten thousand. Preferably, the polyethylene oxide has a molecular weight of 700 ten thousand. The PEO and PAA with the molecular weight of 700 million are used as a solvent and are prepared into an aqueous solution with the molecular weight of 20mg/mL, and the PEO with the molecular weight of 700 million is selected because the higher the molecular weight of the polymer is, the higher the viscosity of the polymer is, so that the PEO solution can serve as a thickening agent and has a dispersing effect in the battery coating slurry.
Preferably, the preparation method further comprises a wetting agent and a binder, and the coating slurry is prepared by mixing the complex solution and the wetting agent in the step (A), adding the ceramic powder and the binder, and stirring and mixing. The wetting agent can increase the wettability of the slurry, the complex solution and the wetting agent are mixed during preparation, the dispersibility of the subsequently added ceramic powder can be increased, the ceramic powder is uniformly dispersed in the complex solution, the uniformity of the slurry is ensured, the binder is added at last, the slurry can be easily coated and fixed on the pole piece, meanwhile, the solid content of the slurry can be adjusted by adding the binder with a certain content, and the leveling property of the slurry is better.
Preferably, the weight parts of the ceramic powder, the complex solution, the binder and the wetting agent are 80-90: 8-12: 0.5-2: 3-6. Preferably, the weight parts of the ceramic powder, the complex solution, the binder and the wetting agent are 84:10:1: 5. The integrated pole piece prepared by adjusting the use amounts of the ceramic powder, the complex solution, the binder and the wetting agent has better performance.
Preferably, the dispersing wetting agent is a silicone-based dispersing wetting agent or an ether-based dispersing wetting agent.
Preferably, the solid content of the coating slurry in the step (B) is 35-55%. Preferably, the solid content of the coating slurry in the step (D) is 40%. The solid content of the slurry is designed to be 40-60% of high solid content, so that the coating thickness can be adjusted conveniently by a coating process, the high solid content can effectively prevent large gaps, and the short circuit risk of the battery cell is reduced. Meanwhile, the solid content of the complex solution is 10% -20%, which cannot be too high, otherwise the battery cell is easy to soften, and cannot be too low, otherwise the liquid retention and the overall improvement effect on the coating are not obvious.
3. A secondary battery comprises a positive electrode, a negative electrode, electrolyte and a shell, wherein the positive electrode and/or the negative electrode are/is the integrated pole piece.
According to the secondary battery, the pole piece has good wettability and liquid retention to electrolyte, high temperature resistance, good safety, difficulty in short circuit and long service life.
Wherein, the positive electrode comprises a positive electrode plate 1 and a positive active material arranged on the positive electrode plate 1, and the positive active material can be a chemical formula including but not limited to LiaNixCoyMzO2-bNb(wherein a is more than or equal to 0.95 and less than or equal to 1.2, x>0, y is more than or equal to 0, z is more than or equal to 0, and x + y + z is 1,0 is more than or equal to b and less than or equal to 1, M is selected from one or more of Mn and Al, N is selected from one or more of F, P and S), and the positive electrode active material can also be selected from one or more of LiCoO (lithium LiCoO), but not limited to2、LiNiO2、LiVO2、LiCrO2、LiMn2O4、LiCoMnO4、Li2NiMn3O8、LiNi0.5Mn1.5O4、LiCoPO4、LiMnPO4、LiFePO4、LiNiPO4、LiCoFSO4、CuS2、FeS2、MoS2、NiS、TiS2And the like. The positive electrode active material may also be subjected to a modification treatment, and the method of subjecting the positive electrode active material to a modification treatment should be known to those skilled in the art, for exampleThe positive electrode active material may be modified by coating, doping, etc., and the material used in the modification treatment may be one or a combination of more of Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce, W, etc., but is not limited thereto. The positive electrode sheet 1 is generally a structure or a part for collecting current, and the positive electrode sheet 1 may be any material suitable for use as a positive electrode sheet 1 of a lithium ion battery in the art, for example, the positive electrode sheet 1 may include, but is not limited to, a metal foil, and more specifically, may include, but is not limited to, an aluminum foil, and the like.
The negative electrode comprises a negative electrode plate 1 and a negative active material arranged on the surface of the negative electrode plate 1, wherein the negative active material can be one or more of graphite, soft carbon, hard carbon, carbon fiber, mesocarbon microbeads, silicon-based materials, tin-based materials, lithium titanate or other metals capable of forming an alloy with lithium. Wherein, the graphite can be selected from one or more of artificial graphite, natural graphite and modified graphite; the silicon-based material can be one or more selected from simple substance silicon, silicon-oxygen compound, silicon-carbon compound and silicon alloy; the tin-based material can be one or more selected from simple substance tin, tin oxide compound and tin alloy. The negative electrode tab 1 is generally a structure or a part for collecting current, and the negative electrode tab 1 may be any material suitable for use as a negative electrode tab 1 of a lithium ion battery in the art, for example, the negative electrode tab 1 may include, but is not limited to, a metal foil, and more specifically, may include, but is not limited to, a copper foil, and the like.
The lithium ion battery also comprises electrolyte, and the electrolyte comprises an organic solvent, electrolyte lithium salt and an additive. Wherein the electrolyte lithium salt may be LiPF used in a high-temperature electrolyte6And/or LiBOB; or LiBF used in low-temperature electrolyte4、LiBOB、LiPF6At least one of; or LiBF used in anti-overcharge electrolyte4、LiBOB、LiPF6At least one of, LiTFSI; may also be LiClO4、LiAsF6、LiCF3SO3、LiN(CF3SO2)2At least one of (1). And the organic solvent may be a cyclic carbonate including PCEC; or chain carbonates including DFC, DMC, or EMC; and also carboxylic acid esters including MF, MA, EA, MP, etc. And additives include, but are not limited to, film forming additives, conductive additives, flame retardant additives, overcharge prevention additives, control of H in the electrolyte2At least one of additives of O and HF content, additives for improving low temperature performance, and multifunctional additives.
The material of the shell includes but is not limited to one of aluminum plastic film, aluminum plate, tin plate and stainless steel.
4. A battery module includes a plurality of electrically connected secondary batteries.
The battery module provided by the invention has the advantages of good safety performance, high capacity and long service life.
The integrated pole piece, the secondary battery, and the battery module described in the embodiments of the present application are applicable to various devices using a battery, such as a mobile phone, a portable device, a notebook computer, a battery car, an electric car, a ship, a spacecraft, an electric toy, an electric tool, and the like, for example, a spacecraft including an airplane, a rocket, a space shuttle, a spacecraft, and the like, an electric toy including a stationary type or a mobile type electric toy, for example, a game machine, an electric car toy, an electric ship toy, an electric plane toy, and the like, an electric tool including a metal cutting electric tool, a grinding electric tool, an assembly electric tool, and an electric tool for a railway, for example, an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an electric impact drill, a concrete vibrator, and an electric planer.
The integrated pole piece, the secondary battery and the battery module described in the embodiments of the present application are not only limited to be applied to the above-described devices, but also applicable to all devices using batteries.
Example 1
1. A preparation method of an integrated pole piece comprises the following steps:
step (A): adding polyoxyethylene and polyacrylic acid into a solvent, mixing and stirring to form a complex solution;
step (B): mixing the complex solution in the step (A) with a wetting agent, adding ceramic powder and a binder, and stirring and mixing to prepare coating slurry;
step (C): and (C) coating and drying the coating slurry in the step (B) on at least one surface of the pole piece 1 to form a diaphragm slurry layer 2, wherein the process is shown in figure 2, and the prepared integrated pole piece is shown in figures 6 and 7.
Wherein the weight portion of the polyoxyethylene and the polyacrylic acid in the step (A) is 1: 0.6.
Wherein the molecular weight of the polyethylene oxide is 700 ten thousand.
Wherein the weight parts of the ceramic powder, the complex solution, the binder and the wetting agent are 84:10:1: 5.
Wherein the dispersing wetting agent is a silicone dispersing wetting agent.
Wherein the solid content of the coating slurry in the step (D) is 40%.
The integrated pole piece is used for the positive pole and the negative pole, the PP diaphragm is used for the diaphragm, and Ethylene Carbonate (EC), dimethyl carbonate (DMC) and fluoroethylene carbonate (FEC) are uniformly mixed in a drying room according to the volume ratio of 45:45:10 to obtain the organic mixed solvent. Adding LiPF to the organic mixed solvent6Obtaining LiPF6And (3) electrolyte with the concentration of 1mol/L, and a positive electrode, a diaphragm, a negative electrode and the electrolyte are filled into a shell to prepare the soft-package laminated battery with the capacity of 170 mAh.
Example 2
The difference from the embodiment 1 is that:
the weight portion of the polyoxyethylene and the polyacrylic acid in the step (A) is 2: 0.6.
The rest is the same as embodiment 1, and the description is omitted here.
Example 3
The difference from the embodiment 1 is that:
the weight portion of the polyoxyethylene and the polyacrylic acid in the step (A) is 3: 0.6.
The rest is the same as embodiment 1, and the description is omitted here.
Example 4
The difference from the embodiment 1 is that:
the weight portion of the polyoxyethylene and the polyacrylic acid in the step (A) is 1: 0.8.
The rest is the same as embodiment 1, and the description is omitted here.
Example 5
The difference from the embodiment 1 is that:
the weight parts of the polyoxyethylene and the polyacrylic acid in the step (A) are 1: 1.
The rest is the same as embodiment 1, and the description is omitted here.
Example 6
The difference from the embodiment 1 is that:
the weight parts of the ceramic powder, the complex solution, the binder and the wetting agent are 80:10:1: 5.
The rest is the same as embodiment 1, and the description is omitted here.
Example 7
The difference from the embodiment 1 is that:
the weight parts of the ceramic powder, the complex solution, the binder and the wetting agent are 82:10:1: 5. The rest is the same as embodiment 1, and the description is omitted here.
Example 8
The difference from the embodiment 1 is that:
the weight parts of the ceramic powder, the complex solution, the binder and the wetting agent are 86:10:1: 5.
The rest is the same as embodiment 1, and the description is omitted here.
Example 9
The difference from the embodiment 1 is that:
the weight parts of the ceramic powder, the complex solution, the binder and the wetting agent are 90:10:1: 5.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 1
The difference from the embodiment 1 is that:
the positive electrode comprises a positive pole piece 1 and a positive electrode coated on the surface of the positive pole piece 1The positive electrode active material is Li2NiMn3O8And the negative electrode adopts the integrated pole piece.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 2
The difference from the embodiment 1 is that:
the negative electrode comprises a negative electrode pole piece 1 and a negative active material coated on the surface of the negative electrode pole piece 1, the negative active material is carbon fiber, and the positive electrode uses the integrated pole piece.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 3
The difference from the embodiment 1 is that:
aluminum foil is used for the positive electrode and the negative electrode, and a PP diaphragm is used for the diaphragm.
The rest is the same as embodiment 1, and the description is omitted here.
Performance testing
1. And (3) wettability testing: during testing, cutting the diaphragm sample into a certain size, soaking the diaphragm sample in the electrolyte for 0.5h at normal temperature, wherein the weight difference of the diaphragm sample per unit area before and after soaking is the liquid absorption amount;
2. and (3) high temperature resistance test: the batteries prepared in examples 1 to 9 and comparative examples 1 to 3 were stored in a storage tank at 200 ℃ for seven days, and the results were recorded after the end, with the results of example 1 shown in fig. 4 and the results of comparative example 3 shown in fig. 5.
TABLE 1
Figure BDA0003155421230000121
As can be seen from the above Table 1, the integrated pole piece of the invention has strong liquid absorption to the electrolyte, and the liquid absorption amount reaches 1.64mg/cm2This is because PEO in the separator slurry of the present invention has an ether-oxygen unshared electron pair and has a strong affinity for hydrogen bonding, and polyacrylic acid (PAA) is a water-soluble high-molecular polymer which still has an affinity for electrolyte after the complexation reaction of the two. Example 1 relative to comparative example 1.08mg/cm2The liquid absorption amount is improved by 34%, and the liquid retention rate is good after 500 times of cyclic charge and discharge, reaches 96.7%, and is improved by 23% compared with 74.3% of comparative example 2. As shown in fig. 3, it can be seen from the result of the liquid drop diffusivity test of the integrated pole piece of the present invention and the diaphragm of the prior art that when the integrated pole piece of the present invention has instant liquid absorption property, the integrated pole piece of the present invention can absorb the electrolyte within a short time, and as can be seen from fig. 3, the integrated pole piece in the lens is wetted with electrolytic wetting at 10s, whereas the diaphragm of the prior art has only half of the wetted area of the electrolyte, and the wetting property and speed are poor.
As can be seen from the comparison of FIG. 4 and FIG. 5, the integrated electrode plate of the present invention has high temperature resistance, no discoloration and no combustion in a storage tank at 200 ℃, and the integrated electrode plate is intact, while the battery of comparative example 3 using the existing electrode plate and diaphragm burns at about 150 ℃, and the case is left after the battery reaches 200 ℃, and the high temperature resistance is poor.
Variations and modifications to the above-described embodiments may also occur to those skilled in the art, which fall within the scope of the invention as disclosed and taught herein. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (10)

1. An integrated pole piece is characterized in that: comprises that
Pole pieces;
and the diaphragm slurry layer is arranged on at least one side surface of the pole piece and comprises ceramic powder and a polyethylene oxide and polyacrylic acid complex.
2. The integrated pole piece of claim 1, wherein: the thickness of diaphragm thick liquids layer is 3 ~ 8 um.
3. A preparation method of an integrated pole piece is characterized by comprising the following steps: the method comprises the following steps:
step (A): adding polyoxyethylene and polyacrylic acid into a solvent, mixing and stirring to form a complex solution;
step (B): mixing the complex solution and the ceramic powder in the step (A) to obtain coating slurry;
step (C): and (C) coating and drying the coating slurry in the step (B) on at least one surface of the pole piece to form a diaphragm slurry layer.
4. The preparation method of the integrated pole piece according to claim 3, characterized in that: in the step (A), the weight parts of polyoxyethylene and polyacrylic acid are 1-3: 0.5-1.
5. The preparation method of the integrated pole piece according to claim 3, characterized in that: the molecular weight of the polyoxyethylene is 600-800 ten thousand.
6. The preparation method of the integrated pole piece according to claim 3, characterized in that: the preparation method also comprises a wetting agent and a binder, and the coating slurry is prepared by mixing the complex solution and the wetting agent in the step (A), adding the ceramic powder and the binder, and stirring and mixing.
7. The preparation method of the integrated pole piece according to claim 6, characterized in that: the weight parts of the ceramic powder, the complex solution, the binder and the wetting agent are 80-90: 8-12: 0.5-2: 3-6.
8. The preparation method of the integrated pole piece according to claim 3, characterized in that: the solid content of the coating slurry prepared in the step (B) is 35-55%.
9. A secondary battery, characterized in that: the lithium ion battery comprises a positive electrode, a negative electrode, electrolyte and a shell, wherein the positive electrode and/or the negative electrode is the integrated pole piece in any one of claims 1 or 2.
10. A battery module, characterized in that: the secondary battery of claim 9 comprising a plurality of electrical connections.
CN202110781741.8A 2021-07-09 2021-07-09 Integrated pole piece and preparation method thereof, secondary battery and battery module Pending CN113690543A (en)

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CN112615111A (en) * 2020-12-08 2021-04-06 惠州锂威电子科技有限公司 High-liquid-retention self-repairing diaphragm, preparation method thereof and lithium ion battery

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CN104396048A (en) * 2012-11-02 2015-03-04 阿科玛股份有限公司 Integrated electrode separator assemblies for lithium ion batteries
CN105958112A (en) * 2016-06-24 2016-09-21 合肥国轩高科动力能源有限公司 Non-diaphragm lithium ion battery coiled core and preparation method therefor
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Application publication date: 20211123