WO2021238709A1 - 一种多层复合正极极片及含有该极片的二次电池 - Google Patents

一种多层复合正极极片及含有该极片的二次电池 Download PDF

Info

Publication number
WO2021238709A1
WO2021238709A1 PCT/CN2021/094177 CN2021094177W WO2021238709A1 WO 2021238709 A1 WO2021238709 A1 WO 2021238709A1 CN 2021094177 W CN2021094177 W CN 2021094177W WO 2021238709 A1 WO2021238709 A1 WO 2021238709A1
Authority
WO
WIPO (PCT)
Prior art keywords
active material
positive electrode
positive
layer
coating
Prior art date
Application number
PCT/CN2021/094177
Other languages
English (en)
French (fr)
Inventor
唐伟超
李素丽
赵伟
陈若凡
刘春洋
李俊义
徐延铭
Original Assignee
珠海冠宇电池股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 珠海冠宇电池股份有限公司 filed Critical 珠海冠宇电池股份有限公司
Publication of WO2021238709A1 publication Critical patent/WO2021238709A1/zh
Priority to US18/070,172 priority Critical patent/US20230089391A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/574—Devices or arrangements for the interruption of current
    • H01M50/581—Devices or arrangements for the interruption of current in response to temperature
    • 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
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/586—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries inside the batteries, e.g. incorrect connections of electrodes
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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

Definitions

  • the present invention relates to the field of high-safety secondary batteries, in particular to a multilayer composite positive pole piece and a secondary battery containing the positive pole piece.
  • Secondary batteries mainly include lithium-ion batteries, lead-acid batteries, sodium-ion batteries, fluoride-ion batteries, zinc-ion batteries, nickel-hydrogen batteries and other secondary batteries.
  • lithium-ion batteries have the advantages of high energy density, long life, environmental protection, etc., and are currently mainly used in energy storage, digital electronics, power vehicles and other fields. In recent years, the market has put forward higher energy density requirements for lithium-ion batteries.
  • Conventional lithium-ion batteries are mainly composed of a positive electrode, a negative electrode, an electrolyte, and a separator. Since the electrolyte in lithium ion batteries is mainly composed of organic solvents, there are safety problems such as leakage, fire and explosion during use.
  • the main programs currently include PTC coating, high-safety diaphragm, high-safety electrolyte, and PTC tabs.
  • the main improvement directions of high-safety diaphragms include safe substrates and safe coating layers; high-safety electrolytes mainly develop high-safety additives and high-safety flame retardants.
  • PTC coating has good safety.
  • certain progress has been made in the direction of high-safety diaphragms, high-safety electrolytes and PTC tabs, but the improvement effect is limited.
  • PTC coatings have high resistance, poor thermal barrier properties, poor solvent compatibility, and poor PTC effects in actual applications. .
  • the purpose of the present invention is to provide a multilayer composite positive pole piece and a secondary battery containing the positive pole piece.
  • the multilayer composite positive electrode piece includes a positive electrode current collector, at least one layer of thermosensitive coating, at least one layer of composite fusion layer and at least one layer of positive electrode active material; the surface of the positive electrode collector is sequentially provided with a thermosensitive coating and a positive electrode An active material layer, and a composite fusion layer is arranged between the thermosensitive coating and the positive electrode active material layer; the thermosensitive coating has conductivity and high temperature blocking properties, and at the same time has a small effect on the internal resistance of the secondary battery.
  • the positive pole piece will not produce any adverse effects in the normal use environment.
  • thermosensitive polymer microspheres in the thermosensitive coating will melt to form multiple continuous electronic barrier layers.
  • a current block is formed, and an internal block is formed inside the battery to prevent the occurrence of further thermal runaway of the secondary battery, and fundamentally solve the safety problem of the secondary battery.
  • a multilayer composite positive pole piece comprising a positive electrode current collector, an N-layer thermosensitive coating, a P-layer composite fusion layer and an M-layer positive active material layer, wherein the positive electrode current collector is alternately arranged on the surface
  • the N-layer thermosensitive coating and the M-layer positive active material layer, and a composite fusion layer is arranged between the thermosensitive coating and the positive active material layer; N ⁇ 1, N+1 ⁇ M ⁇ N-1, and M ⁇ 1.
  • P N+M-1;
  • the heat-sensitive coating includes heat-sensitive polymer microspheres, a first positive electrode active material, a first conductive agent, a first binder, and an auxiliary agent;
  • the positive active material layer includes a second positive active material, a second conductive agent, and a second binder;
  • the composite fusion layer includes a first positive electrode active material, a second positive electrode active material, thermosensitive polymer microspheres, a first conductive agent, a first binder, a second conductive agent, a second binder, and an auxiliary agent.
  • sequence can be one of the following:
  • Positive electrode current collector positive electrode active material layer, heat-sensitive coating, positive electrode active material layer, heat-sensitive coating,..., positive electrode active material layer, heat-sensitive coating, positive electrode active material layer;
  • Positive electrode current collector positive electrode active material layer, heat-sensitive coating, positive electrode active material layer, heat-sensitive coating,..., positive electrode active material layer, heat-sensitive coating.
  • the positive electrode piece includes a positive electrode current collector, a layer of thermosensitive coating, a layer of composite fusion layer and a layer of positive electrode active material, wherein the thermosensitive coating and the layer of positive electrode active material are sequentially arranged on the surface of the positive electrode collector
  • a positive active material layer, and a composite fusion layer is arranged between the thermosensitive coating and the positive active material layer, that is, a thermosensitive coating, a composite fusion layer, and a positive active material layer are sequentially arranged on the surface of the positive electrode current collector; or, the positive electrode
  • the surface of the current collector is sequentially provided with a positive electrode active material layer, a composite fusion layer and a heat-sensitive coating.
  • the positive electrode piece includes a positive electrode current collector, two layers of thermosensitive coatings, two layers of composite fusion layer and one layer of positive electrode active material, wherein the thermosensitive coating is alternately arranged on the surface of the positive electrode current collector.
  • Layer and positive active material layer, and a composite fusion layer is arranged between the thermosensitive coating and the positive active material layer, that is, the surface of the positive current collector is sequentially arranged with a thermosensitive coating, a composite fusion layer, a positive active material layer, and a composite fusion layer , Thermal coating.
  • the positive electrode piece includes a positive electrode current collector, 2 layers of thermosensitive coatings, 3 layers of composite fusion layers, and 2 layers of positive electrode active material layers, wherein the thermosensitive coatings are alternately arranged on the surface of the positive electrode current collector.
  • Layer and positive active material layer, and a composite fusion layer is arranged between the thermosensitive coating and the positive active material layer, that is, the surface of the positive current collector is sequentially arranged with a thermosensitive coating, a composite fusion layer, a positive active material layer, and a composite fusion layer , Heat-sensitive coating, composite fusion layer, positive electrode active material layer, or the positive electrode current collector is provided with a positive electrode active material layer, a composite fusion layer, a heat-sensitive coating, a composite fusion layer, a positive active material layer, and a composite fusion layer in sequence , Thermal coating.
  • the positive electrode piece includes a positive electrode current collector, a thermosensitive coating layer, two composite fusion layers and two positive electrode active material layers, wherein the thermosensitive coating is alternately arranged on the surface of the positive electrode current collector.
  • Layer and the positive active material layer, and a composite fusion layer is arranged between the thermosensitive coating and the positive active material layer, that is, the positive electrode active material layer, the composite fusion layer, the heat sensitive coating, and the composite fusion layer are sequentially arranged on the surface of the positive electrode current collector , Positive active material layer.
  • the composition of the N-layer thermosensitive coating is the same or different.
  • the heat-sensitive coating includes the following components by weight percentage:
  • 5-90wt% thermal polymer microspheres 5-90wt% first positive electrode active material, 2.9-40wt% first conductive agent, 2-20wt% first binder, and 0.1-5wt% auxiliary Agent.
  • the heat-sensitive coating includes the following components by weight percentage:
  • thermosensitive polymer microspheres 10-80wt% thermosensitive polymer microspheres, 10-80wt% first positive electrode active material, 6.9-30wt% first conductive agent, 3-20wt% first binder, and 0.1-5wt% auxiliary Agent.
  • the heat-sensitive coating includes the following components by weight percentage:
  • thermosensitive polymer microspheres 20-65wt% of thermosensitive polymer microspheres, 20-65wt% of the first positive electrode active material, 10-25wt% of the first conductive agent, 4.5-15wt% of the first binder, and 0.5-4wt% of the auxiliary Agent.
  • the weight percentage of the thermosensitive polymer microspheres is 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt% %, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%.
  • the weight percentage of the first positive electrode active material is 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt% , 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%.
  • the weight percentage of the first conductive agent is 2.9wt%, 3wt%, 4wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt% , 28wt%, 30wt%, 35wt%, 40wt%.
  • the weight percentage of the first binder is 2wt%, 4wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%.
  • the weight percentage of the auxiliary agent is 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%.
  • the composition of the M-layer positive active material layer is the same or different.
  • the positive active material layer includes the following components by weight percentage:
  • the positive active material layer includes the following components by weight percentage:
  • the positive electrode active material layer includes the following components by weight percentage:
  • the composite fusion layer is formed by mutual penetration of the thermosensitive coating and the positive active material layer during the preparation process.
  • the mass percentages of the thermosensitive polymer microspheres, the first positive electrode active material, the first conductive agent, the first binder and the auxiliary agent in the composite fusion layer meet: 5-90wt% of the thermosensitive polymer Microspheres, 5-90wt% of the first positive electrode active material, 2.9-40wt% of the first conductive agent, 2-20wt% of the first binder, and 0.1-5wt% of the auxiliary agent.
  • the mass percentage content of the positive electrode active material, the second conductive agent and the second binder in the composite fusion layer satisfies: 80-99wt% of the positive electrode active material, 0.5-10wt% of the second conductive agent and 0.5- 10wt% of the second binder.
  • the mass ratio of each component in the composite fusion layer is not specifically defined, and it is contained at the same time, and only needs to satisfy the above definition.
  • the thickness of the current collector is 0.1 ⁇ m-20 ⁇ m, preferably 2 ⁇ m-15 ⁇ m, such as 0.5 ⁇ m, 1 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m.
  • the thickness of the heat-sensitive coating is 0.1 ⁇ m-5 ⁇ m, preferably 0.2 ⁇ m-3 ⁇ m, such as 0.3 ⁇ m, 0.5 ⁇ m, 0.8 ⁇ m, 1 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m.
  • the thickness of the composite fusion layer is 0.001-0.5 ⁇ m, such as 0.001 ⁇ m, 0.005 ⁇ m, 0.01 ⁇ m, 0.02 ⁇ m, 0.05 ⁇ m, 0.08 ⁇ m, 0.1 ⁇ m, 0.2 ⁇ m, 0.3 ⁇ m, 0.4 ⁇ m, 0.5 ⁇ m .
  • the thickness of the positive electrode active material layer is 5-175 ⁇ m, preferably 5 ⁇ m-65 ⁇ m, such as 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 45 ⁇ m, 50 ⁇ m, 55 ⁇ m, 60 ⁇ m, 65 ⁇ m, 70 ⁇ m , 80 ⁇ m, 90 ⁇ m, 100 ⁇ m, 120 ⁇ m, 130 ⁇ m, 140 ⁇ m, 150 ⁇ m, 160 ⁇ m, 170 ⁇ m, 175 ⁇ m.
  • 5 ⁇ m-65 ⁇ m such as 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 45 ⁇ m, 50 ⁇ m, 55 ⁇ m, 60 ⁇ m, 65 ⁇ m, 70 ⁇ m , 80 ⁇ m, 90 ⁇ m, 100 ⁇ m, 120 ⁇ m, 130 ⁇ m, 140 ⁇ m, 150 ⁇ m, 160 ⁇ m, 170 ⁇ m, 175 ⁇ m.
  • the particle size of the thermosensitive polymer microspheres is 100 nm-3.0 ⁇ m, preferably 200 nm-2 ⁇ m.
  • thermosensitive temperature of the thermosensitive polymer microspheres is greater than or equal to 110°C, preferably 115°C-160°C, such as 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C °C, 150°C, 160°C.
  • the thermosensitive polymer microspheres can be purchased commercially.
  • thermosensitive polymer microspheres are selected from polyethylene, polypropylene, polyamide, polyester amide, polystyrene, polyvinyl chloride, polyester, polyurethane, olefin copolymers or monomer-modified copolymers thereof Of polymers.
  • the olefin copolymer is, for example, a propylene copolymer (such as a propylene-ethylene-acrylate copolymer, exemplarily, the molar ratio of propylene to ethylene/acrylate is (10-1):1), ethylene copolymer (For example, ethylene-propylene copolymer, the molar ratio of ethylene to propylene is (10-1):1; for example, ethylene-acrylate copolymer, the molar ratio of ethylene to acrylate is (10-1) ):1; also for example ethylene-vinyl acetate copolymer) and so on.
  • a propylene copolymer such as a propylene-ethylene-acrylate copolymer, exemplarily, the molar ratio of propylene to ethylene/acrylate is (10-1):1)
  • ethylene copolymer (For example, ethylene-propylene copolymer, the molar ratio of ethylene to propylene is (10-
  • the first conductive agent and the second conductive agent are the same or different, and are independently selected from conductive carbon black, Ketjen black, conductive fiber, conductive polymer, acetylene black, carbon nanotube, graphene, flake One or more of graphite, conductive oxide, and metal particles.
  • the first binder is selected from water-based binders and oil-based binders, wherein the water-based binder is acrylate, poly(meth)acrylic acid, styrene butadiene rubber (SBR), polyvinyl alcohol , Polyvinyl acetate, carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (CMC-Li), carboxyethyl cellulose, water-based polyurethane, ethylene-vinyl acetate copolymer, polyacrylic copolymer, poly One or more of lithium styrene sulfonate, water-based silicone resin, nitrile-polyvinyl chloride blends, styrene-acrylic latex, pure benzene latex, etc., and blends and copolymers derived from the aforementioned polymer modification A combination; wherein the oil-based binder is one or more combinations of polytetrafluoroethylene, polyvinylidene fluor
  • the auxiliary agent is selected from at least one of dispersant and filler; wherein the dispersant is branched chain alcohol, triethyl phosphate, polyethylene glycol, fluorinated polyethylene oxide, polyethylene oxide, and stearin At least one of acid, sodium dodecylbenzene sulfonate, sodium cetyl sulfonate, fatty acid glyceride, sorbitan fatty acid ester and polysorbate; the filler is nano filler (nano silica, three Aluminum oxide, zirconium dioxide, boron nitride, aluminum nitride, etc.), nano oxide electrolyte, etc.
  • the dispersant is branched chain alcohol, triethyl phosphate, polyethylene glycol, fluorinated polyethylene oxide, polyethylene oxide, and stearin At least one of acid, sodium dodecylbenzene sulfonate, sodium cetyl sulfonate, fatty acid gly
  • the first cathode active material and second cathode active materials are the same or different, each independently selected from lithium iron phosphate (LiFePO 4), lithium cobaltate (LiCoO 2), lithium nickel cobalt manganese oxide (Li z Ni x Co y Mn 1-xy O 2 , where 0.95 ⁇ z ⁇ 1.05, x>0, y>0, 0 ⁇ x+y ⁇ 1), lithium manganate (LiMnO 2 ), lithium nickel cobalt aluminate (Li z Ni x Co y Al 1-xy O 2 , where 0.95 ⁇ z ⁇ 1.05, x>0, y>0, 0.8 ⁇ x+y ⁇ 1), lithium nickel cobalt manganese aluminate (Li z Ni x Co y Mn w Al 1-xyw O 2 , where 0.95 ⁇ z ⁇ 1.05, x>0, y>0, w>0, 0.8 ⁇ x+y+w ⁇ 1), nickel-co
  • the second binder is selected from one or more combinations of polytetrafluoroethylene (PTEF), polyvinylidene fluoride (PVDF), and polyvinylidene fluoride-hexafluoropropylene.
  • the resistance of the positive pole piece is ⁇ 10 ⁇ , preferably ⁇ 500m ⁇ .
  • the thickness of the positive pole piece is 50-200 ⁇ m.
  • the present invention also provides a secondary battery including the above-mentioned positive pole piece.
  • the number of cycles is 1100 or more.
  • the present invention also provides a method for preparing the above-mentioned positive pole piece, and the method includes the following steps:
  • step 1) or the positive electrode active material layer slurry of step 2) are alternately coated on the surface of the positive electrode current collector, and dried at 80-110°C for 12-72 hours to obtain the Positive pole piece.
  • the solvent is selected from at least one of N-methylpyrrolidone, hydrofluoroether, acetone, tetrahydrofuran, dichloromethane, and pyridine.
  • step 1) specifically includes the following steps:
  • step 3 specifically includes the following steps:
  • the N-layer thermosensitive coating and the M-layer positive active material layer are alternately coated on the surface of the positive electrode current collector in order, and the thermosensitive coating and the positive active material layer are respectively dried after coating.
  • the invention provides a multilayer composite positive pole piece and a secondary battery containing the positive pole piece.
  • the multilayer composite positive electrode piece includes a positive electrode current collector, at least one layer of thermosensitive coating, at least one layer of composite fusion layer and at least one layer of positive electrode active material; the surface of the positive electrode collector is sequentially provided with a thermosensitive coating and a positive electrode Active material layer, and a composite fusion layer is arranged between the heat-sensitive coating and the positive electrode active material layer; the heat-sensitive coating includes a first conductive agent, a first binder, a first positive electrode active material, and a heat-sensitive polymer micro Balls and additives.
  • the heat-sensitive coating has electrical conductivity at room temperature, and at the same time has the advantages of increasing the contact area between the active material and the current collector and effectively reducing the polarization of the battery; the heat-sensitive coating incorporates the first
  • the positive electrode active material not only maintains the high safety of the positive electrode piece, but also increases the overall active material content in the positive electrode piece and improves the overall energy density of the battery; when the use temperature of the positive electrode piece reaches the heat-sensitive temperature and above At temperature, the thermosensitive polymer microspheres will melt to form at least one continuous electron barrier layer, and the coating forms a current block, forming an internal block inside the battery, preventing further thermal runaway of the secondary battery and improving the safety performance of the secondary battery .
  • FIG. 1 is a schematic diagram of the normal temperature structure of the positive pole piece of the present invention.
  • FIG. 2 is a schematic diagram of the high temperature structure of the positive pole piece of the present invention.
  • Fig. 3 is the change curve of the resistance value of the positive pole piece of Example 10 and Comparative Example 1-2 as the temperature increases.
  • Figure 4 shows the ARC test results of the batteries prepared in Example 10 and Comparative Example 1-2.
  • thermosensitive polymer microspheres used in the following examples were all purchased from commercial sources.
  • thermosensitive coating slurry After mixing 1000g of N-methylpyrrolidone, 26g of lithium cobaltate, 13g of carbon nanotubes, 15g of polyvinylidene fluoride, and 7g of triethyl phosphate evenly through a 100 mesh screen, add 39g of polyethylene thermosensitive polymer microspheres are uniformly mixed and passed through a 100-mesh screen to obtain a thermosensitive coating slurry;
  • thermosensitive coating (denoted as the first layer) of the positive pole piece, in which the thermosensitive coating and the positive active material layer infiltrate each other during the drying and pressing process to form a composite fusion layer, through the scanning electron microscope and EDS energy Spectral analysis can observe the thickness of the composite fusion layer;
  • Example 2-12 and Comparative Example 1-2 are prepared by the method of multi-layer coating of materials.
  • the difference is that the composition of the heat-sensitive coating slurry in step S1 is different, and that in step S2
  • the composition of the positive electrode slurry is different, and the order of the slurry coated on the surface of the positive electrode current collector in step S3 is different, as shown in Table 1-2, where the layer directly in contact with the positive electrode current collector is marked as the first Layers are denoted as the second layer, the third layer, and so on.
  • Example 2 Example 4, and Example 5 were prepared by a laminated method
  • the batteries of Example 1, Example 3, Examples 6-12 and Comparative Examples 1-2 were prepared by a winding method.
  • Pole piece resistance test ACCFILM diaphragm resistance test instrument is used, which uses a controllable voltage double probe resistance to directly test the overall resistance of the pole piece, and the output measurement value is the pole piece resistance.
  • test process is as follows: Test the probe by applying a suitable surface flatness to the probe and applying a pressure of 10N. The test device was placed in an oven, the initial temperature of the oven was 20°C, and the temperature was raised to 145°C at a heating rate of 2°C/min, and the data was recorded in real time.
  • AC impedance test method for battery internal resistance Use Metrohm PGSTAT302N ChemStation to perform AC impedance test on lithium-ion batteries under the range of 100KHz-0.1mHz and at 25°C;
  • Battery cycle performance test method Li-ion battery is charged and discharged in a blue battery charge and discharge test cabinet under the test conditions of 25°C, 50% humidity, 1C/1C charge and discharge.
  • Battery thermal test method The British HEL brand-PhiTEC I (ARC) model adiabatic accelerating calorimeter is used to test the battery status at different temperatures.
  • Pole piece resistance test results Figure 3 shows the change curve of the resistance value of the positive pole piece of Example 10, Comparative Example 1, and Comparative Example 2 as the temperature increases: It can be seen from Figure 3 that through comparison The resistance test results of the positive pole pieces of Example 10 and Comparative Example 1 and Comparative Example 2 showed that the pole piece resistance of the positive pole pieces of Comparative Example 1 and Comparative Example 2 decreased slightly in the entire temperature range of 20-140°C; Example 10 When the positive pole piece is 20°C-115°C, the resistance of the positive pole piece changes little with temperature. Within 115°C-125°C, the thermosensitive polymer microspheres in the positive pole piece will melt to form multiple continuous electrons. The barrier layer, the coating forms a current block, and the resistance increases by orders of magnitude, which can block the passage of ions and electrons and improve the safety performance of the battery.
  • the thickness of the positive electrode layer in the positive pole piece increases, and the internal resistance of the battery increases accordingly.
  • the main reason is the thickening of the pole pieces, which leads to an increase in the transmission path of lithium ions and electrons, and an increase in battery impedance, which leads to a decrease in the effective cycle of the battery.
  • the internal resistance and cycle performance of the batteries prepared in Examples 1-12 meet the requirements of conventional projects;
  • Example 10-12 In the battery prepared in Examples 10-12: The thickness of the positive electrode layer in the positive electrode pieces of Examples 10-11 is different, the positive electrode layer in the positive layer electrode piece increases by 10 ⁇ m, and the lithium ion and electron transmission path inside the electrode piece increases, The battery impedance increases and the battery performance decreases.
  • the battery of Example 10 has 1320 cycles (the capacity is maintained at 80%), and the battery of Example 11 is 1060 cycles (the capacity is maintained at 80%), which basically meets customer needs;
  • the thickness of the heat-sensitive coating in the positive pole piece is different. Compared with Example 10, the thickness of the heat-sensitive coating in Example 12 is reduced by 2 ⁇ m. The capacity is maintained at 80%), which has a small impact on battery performance, which is within the normal range;
  • Comparative Example 1 (52.71m ⁇ ) ⁇ Example 12 (54.42m ⁇ ) ⁇ Example 10 (55.35m ⁇ ) ⁇ Comparative Example 2 (56.14m ⁇ ).
  • the thickness of the positive electrode active material in Example 10, Example 12, Comparative Example 1, and Comparative Example 2 is the same, and the difference lies in whether it contains a heat-sensitive coating and the thickness of the coating.
  • the main reason is that there is no positive electrode primer in Comparative Example 1, which results in a slightly lower internal resistance of the battery, which has less impact on battery performance;
  • Example 10 battery 1320 cycles (capacity retention 80%)
  • Example 12 battery 1370 cycles (capacity retention 80%)
  • comparative example 1 battery 1120 cycles (capacity retention 80%)
  • comparative example 2 battery 1250 cycles (capacity remains 80%)
  • the main reason is that there is no positive electrode primer in Comparative Example 1.
  • the internal resistance of the battery is slightly lower in the early stage, as the battery cycles, the battery polarization, dynamic internal resistance increase, and positive electrode unevenness, etc. Factors that affect battery cycle.
  • the functional safety coating in the positive pole piece of the present invention can inhibit the polarization of the battery, improve the uniformity of the positive electrode, and improve the battery Cycle life characteristics;

Landscapes

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

Abstract

一种多层复合正极极片及含该正极极片的二次电池。所述多层复合正极极片包括正极集流体、至少一层热敏涂层、至少一层复合融合层和至少一层正极活性物质层；所述热敏涂层在常温下具有导电性能，同时具有增大活性物质与集流体间的接触面积、有效降低电池极化等优点；所述热敏涂层中引入第一正极活性物质，既保持了正极极片的高安全性，又提高了正极极片中的整体活性物质含量，提升电池整体能量密度；当所述正极极片的使用温度达到热敏温度及其以上温度时，热敏聚合物微球会熔融形成至少一个连续电子阻隔层，涂层形成电流阻断，在电池内部形成内部阻断，防止二次电池进一步热失控的发生，提高二次电池安全性能。

Description

一种多层复合正极极片及含有该极片的二次电池 技术领域
本发明涉及高安全性二次电池领域，尤其涉及一种多层复合正极极片及含有该正极极片的二次电池。
背景技术
二次电池中主要有锂离子电池、铅酸电池、钠离子电池、氟离子电池、锌离子电池、镍氢电池等二次电池。其中锂离子电池具有能量密度高、寿命长、环保等优点，目前主要应用于能量存储、数码电子、动力汽车等领域。近年来，市场对锂离子电池提出更高能量密度需求，常规锂离子电池主要由正极、负极、电解液、隔膜构成。由于锂离子电池中电解液主要由有机溶剂构成，在使用过程中存在漏液、起火爆炸等安全性问题。
为改善锂离子电池安全性，目前主要方案有PTC涂层、高安全性隔膜、高安全性电解液、PTC极耳等方案。其中高安全性隔膜主要改善方向有安全基材、安全涂胶层等方向；高安全性电解液主要开发高安全性添加剂、高安全性阻燃剂等方向。PTC涂层具有良好的安全性，目前主要有二次电池外部PTC器件和二次电池内部PTC器件；其中，二次电池外部PTC器件的主要代表是PTC极耳，二次电池内部PTC器件的主要代表为PTC涂层。目前已经在高安全性隔膜、高安全性电解液和PTC极耳方向取得一定进展，但是改善效果有限。
当前重点改善方向为在锂离子电池内部开发一种高安全性的PTC涂层，目前PTC涂层在实际应用过程中存在电阻较高、热阻隔性差、与溶剂相容性差、PTC效应差等问题。
发明内容
为了改善现有技术的不足，本发明的目的是提供一种多层复合正极极片及含该正极极片的二次电池。所述多层复合正极极片包括正极集流体、至少一层热敏涂层、至少一层复合融合层和至少一层正极活性物质层；所述正极集流体表面依次设置热敏涂层和正极活性物质层，且热敏涂层和正极活性物 质层之间设置复合融合层；所述热敏涂层具有导电性和高温阻断性，同时对二次电池内阻影响较小。所述正极极片在常规使用环境下并不会产生任何不良影响，当温度达到热敏温度时，热敏涂层中的热敏聚合物微球会熔融形成多个连续电子阻隔层，涂层形成电流阻断，在电池内部形成内部阻断，防止二次电池进一步热失控的发生，从根本上解决二次电池的安全问题。
本发明目的是通过如下技术方案实现的：
一种多层复合正极极片，所述正极极片包括正极集流体、N层热敏涂层、P层复合融合层和M层正极活性物质层，其中，在正极集流体表面依次交替地设置所述N层热敏涂层和M层正极活性物质层，且热敏涂层和正极活性物质层之间设置复合融合层；N≥1，N+1≥M≥N-1，且M≥1，P＝N+M-1；
所述热敏涂层包括热敏聚合物微球、第一正极活性物质、第一导电剂、第一粘结剂以及助剂；
所述正极活性物质层包括第二正极活性物质、第二导电剂和第二粘结剂；
所述复合融合层包括第一正极活性物质、第二正极活性物质、热敏聚合物微球、第一导电剂、第一粘结剂、第二导电剂、第二粘结剂以及助剂。
根据本发明，所述正极极片包括正极集流体、N层热敏涂层、P层复合融合层和M层正极活性物质层，其中，在正极集流体表面按照顺序依次交替地设置所述N层热敏涂层和M层正极活性物质层，且热敏涂层和正极活性物质层之间设置复合融合层；N≥1，N+1≥M≥N-1，且M≥1，P＝N+M-1；
其中，所述顺序可以是如下中的一种：
(1)正极集流体、热敏涂层、正极活性物质层、热敏涂层、正极活性物质层、……、热敏涂层、正极活性物质层；
(2)正极集流体、热敏涂层、正极活性物质层、热敏涂层、正极活性物质层、……、热敏涂层、正极活性物质层、热敏涂层；
(3)正极集流体、正极活性物质层、热敏涂层、正极活性物质层、热敏涂层、……、正极活性物质层、热敏涂层、正极活性物质层；
(4)正极集流体、正极活性物质层、热敏涂层、正极活性物质层、热敏涂层、……、正极活性物质层、热敏涂层。
根据本发明，4≥N≥1，N+1≥M≥N-1，且M≥1，P＝N+M-1。
优选地，2≥N≥1，N+1≥M≥N-1，且M≥1，P＝N+M-1。
示例性地，所述正极极片包括正极集流体、1层热敏涂层、1层复合融合层和1层正极活性物质层，其中，在正极集流体表面依次设置所述热敏涂层和正极活性物质层，且热敏涂层和正极活性物质层之间设置复合融合层，即所述正极集流体表面依次设置热敏涂层、复合融合层和正极活性物质层；或者，所述正极集流体表面依次设置正极活性物质层、复合融合层和热敏涂层。
示例性地，所述正极极片包括正极集流体、2层热敏涂层、2层复合融合层和1层正极活性物质层，其中，在正极集流体表面依次交替地设置所述热敏涂层和正极活性物质层，且热敏涂层和正极活性物质层之间设置复合融合层，即所述正极集流体表面依次设置热敏涂层、复合融合层、正极活性物质层、复合融合层、热敏涂层。
示例性地，所述正极极片包括正极集流体、2层热敏涂层、3层复合融合层和2层正极活性物质层，其中，在正极集流体表面依次交替地设置所述热敏涂层和正极活性物质层，且热敏涂层和正极活性物质层之间设置复合融合层，即所述正极集流体表面依次设置热敏涂层、复合融合层、正极活性物质层、复合融合层、热敏涂层、复合融合层、正极活性物质层，或者所述正极集流体表面依次设置正极活性物质层、复合融合层、热敏涂层、复合融合层、正极活性物质层、复合融合层、热敏涂层。
示例性地，所述正极极片包括正极集流体、1层热敏涂层、2层复合融合层和2层正极活性物质层，其中，在正极集流体表面依次交替地设置所述热敏涂层和正极活性物质层，且热敏涂层和正极活性物质层之间设置复合融合层，即所述正极集流体表面依次设置正极活性物质层、复合融合层、热敏涂层、复合融合层、正极活性物质层。
根据本发明，所述N层热敏涂层的组成相同或不同。
根据本发明，所述热敏涂层包括如下重量百分含量的各组分：
5-90wt％的热敏聚合物微球、5-90wt％的第一正极活性物质、2.9-40wt％的第一导电剂、2-20wt％的第一粘结剂以及0.1-5wt％的助剂。
优选地，所述热敏涂层包括如下重量百分含量的各组分：
10-80wt％的热敏聚合物微球、10-80wt％的第一正极活性物质、6.9-30wt％的第一导电剂、3-20wt％的第一粘结剂以及0.1-5wt％的助剂。
还优选地，所述热敏涂层包括如下重量百分含量的各组分：
20-65wt％的热敏聚合物微球、20-65wt％的第一正极活性物质、10-25wt％的第一导电剂、4.5-15wt％的第一粘结剂以及0.5-4wt％的助剂。
其中，所述热敏聚合物微球的重量百分含量为5wt％、10wt％、15wt％、20wt％、25wt％、30wt％、35wt％、40wt％、45wt％、50wt％、55wt％、60wt％、65wt％、70wt％、75wt％、80wt％、85wt％、90wt％。
其中，所述第一正极活性物质的重量百分含量为5wt％、10wt％、15wt％、20wt％、25wt％、30wt％、35wt％、40wt％、45wt％、50wt％、55wt％、60wt％、65wt％、70wt％、75wt％、80wt％、85wt％、90wt％。
其中，所述第一导电剂的重量百分含量为2.9wt％、3wt％、4wt％、5wt％、8wt％、10wt％、12wt％、15wt％、18wt％、20wt％、22wt％、25wt％、28wt％、30wt％、35wt％、40wt％。
其中，所述第一粘结剂的重量百分含量为2wt％、4wt％、5wt％、8wt％、10wt％、12wt％、15wt％、18wt％、20wt％。
其中，所述助剂的重量百分含量为0.1wt％、0.5wt％、1wt％、2wt％、3wt％、4wt％、5wt％。
根据本发明，所述M层正极活性物质层的组成相同或不同。
根据本发明，所述正极活性物质层包括如下重量百分含量的各组分：
80-99wt％的正极活性物质、0.5-10wt％的第二导电剂和0.5-10wt％的第二粘结剂。
优选地，所述正极活性物质层包括如下重量百分含量的各组分：
84-99wt％的正极活性物质、0.5-8wt％的第二导电剂和0.5-8wt％的第二粘结剂。
还优选地，所述正极活性物质层包括如下重量百分含量的各组分：
90-98wt％的正极活性物质、1-5wt％的第二导电剂和1-5wt％的第二粘结剂。
根据本发明，所述复合融合层是所述热敏涂层和所述正极活性物质层在制备过程中互相渗透形成的。其中，所述复合融合层中热敏聚合物微球、第一正极活性物质、第一导电剂、第一粘结剂以及助剂的质量百分含量满足：5-90wt％的热敏聚合物微球、5-90wt％的第一正极活性物质、2.9-40wt％的第一导电剂、2-20wt％的第一粘结剂以及0.1-5wt％的助剂。进一步地，所述复合 融合层中正极活性物质、第二导电剂和第二粘结剂质量百分含量满足：80-99wt％的正极活性物质、0.5-10wt％的第二导电剂和0.5-10wt％的第二粘结剂。进一步地，所述复合融合层中各组分的质量比没有特别的定义，同时含有，且满足上述定义即可。
根据本发明，所述集流体的厚度为0.1μm-20μm，优选2μm-15μm，如0.5μm、1μm、3μm、4μm、5μm、8μm、10μm、12μm、15μm。
根据本发明，所述热敏涂层的厚度为0.1μm-5μm，优选0.2μm-3μm，如0.3μm、0.5μm、0.8μm、1μm、1.5μm、2μm、2.5μm、3μm。
根据本发明，所述复合融合层的厚度为0.001-0.5μm，如0.001μm、0.005μm、0.01μm、0.02μm、0.05μm、0.08μm、0.1μm、0.2μm、0.3μm、0.4μm、0.5μm。
根据本发明，所述正极活性物质层的厚度为5-175μm，优选5μm-65μm，如5μm、10μm、15μm、20μm、25μm、30μm、35μm、40μm、45μm、50μm、55μm、60μm、65μm、70μm、80μm、90μm、100μm、120μm、130μm、140μm、150μm、160μm、170μm、175μm。
根据本发明，所述热敏聚合物微球颗粒大小为100nm-3.0μm，优选为200nm-2μm。
根据本发明，所述热敏聚合物微球的热敏温度为大于等于110℃，优选为115℃-160℃，如115℃、120℃、125℃、130℃、135℃、140℃、145℃、150℃、160℃。所述热敏聚合物微球可以是商业途径购买获得的。
根据本发明，所述热敏聚合物微球选自聚乙烯、聚丙烯、聚酰胺、聚酯酰胺、聚苯乙烯、聚氯乙烯、聚酯、聚氨酯、烯烃共聚物或其单体改性共聚的聚合物。示例性地，所述烯烃共聚物例如为丙烯共聚物(如丙烯-乙烯-丙烯酸酯共聚物，示例性地丙烯与乙烯/丙烯酸酯的摩尔比为(10-1):1)、乙烯共聚物(如乙烯-丙烯共聚物，示例性地乙烯与丙烯的摩尔比为(10-1):1；还例如乙烯-丙烯酸酯共聚物，示例性地乙烯与丙烯酸酯的摩尔比为(10-1):1；还例如乙烯-醋酸乙烯共聚物)等。
根据本发明，所述第一导电剂和第二导电剂相同或不同，彼此独立地选自导电炭黑、科琴黑、导电纤维、导电聚合物、乙炔黑、碳纳米管、石墨烯、鳞片石墨、导电氧化物、金属颗粒中的一种或几种。
根据本发明，所述第一粘结剂选自水系粘结剂和油系粘结剂，其中水系粘结剂为丙烯酸酯、聚(甲基)丙烯酸、丁苯橡胶(SBR)、聚乙烯醇、聚醋酸乙烯酯、羧甲基纤维素(CMC)、羧甲基纤维素钠(CMC-Li)、羧乙基纤维素、水性聚氨酯、乙烯-醋酸乙烯共聚物、多元丙烯酸类共聚物、聚苯乙烯磺酸锂、水性有机硅树脂、丁腈-聚氯乙烯共混物、苯丙乳胶、纯苯乳胶等及由前述聚合物改性衍生的共混、共聚聚合物中的一种或多种组合；其中油系粘结剂为聚四氟乙烯、聚偏氟乙烯、聚偏氟乙烯-六氟丙烯中的一种或多种组合。
根据本发明，所述助剂选自分散剂、填充剂中的至少一种；其中分散剂为支链醇、磷酸三乙酯、聚乙二醇、氟化聚氧化乙烯、聚氧化乙烯、硬脂酸、十二烷基苯磺酸钠、十六烷基磺酸钠、脂肪酸甘油酯，山梨坦脂肪酸酯和聚山梨酯中的至少一种；填充剂为纳米填料(纳米二氧化硅、三氧化二铝、二氧化锆、氮化硼、氮化铝等)、纳米氧化物电解质等。
根据本发明，所述第一正极活性物质和第二正极活性物质相同或不同，彼此独立地选自磷酸铁锂(LiFePO 4)、钴酸锂(LiCoO 2)、镍钴锰酸锂(Li zNi xCo yMn 1-x-yO 2，其中0.95≤z≤1.05，x>0，y>0，0<x+y<1)、锰酸锂(LiMnO 2)、镍钴铝酸锂(Li zNi xCo yAl 1-x-yO 2，其中0.95≤z≤1.05，x>0，y>0，0.8≤x+y<1)、镍钴锰铝酸锂(Li zNi xCo yMn wAl 1-x-y-wO 2，其中0.95≤z≤1.05，x>0，y>0，w>0，0.8≤x+y+w<1)、镍钴铝钨材料、富锂锰基固溶体正极材料(xLi 2MnO 3·(1-x)LiMO 2，其中M＝Ni/Co/Mn)、镍钴酸锂(LiNi xCo yO 2，其中x>0，y>0，x+y＝1)、镍钛镁酸锂(LiNi xTi yMg zO 2，其中，x>0，y>0，z>0，x+y+z＝1)、镍酸锂(Li 2NiO 2)、尖晶石锰酸锂(LiMn 2O 4)、镍钴钨材料中的一种或几种的组合。
根据本发明，所述第二粘结剂选自聚四氟乙烯(PTEF)、聚偏氟乙烯(PVDF)、聚偏氟乙烯-六氟丙烯中的一种或多种组合。
根据本发明，所述正极极片的电阻为<10Ω，优选<500mΩ。
根据本发明，所述正极极片的厚度为50-200μm。
本发明还提供一种二次电池，所述二次电池包括上述的正极极片。
根据本发明，所述二次电池在25℃、1C/1C充放电制度下容量保持率降至80％时，循环的次数为大于等于1100次。
本发明还提供一种上述正极极片的制备方法，所述方法包括如下步骤：
1)将200-1000质量份溶剂、5-90质量份热敏聚合物微球、5-90质量份第一正极活性物质、2.9-40质量份第一导电剂、2-20质量份第一粘结剂中的油系粘结剂以及0.1-5质量份助剂，均匀混合后，得到热敏涂层浆料；
2)将200-1000质量份溶剂、80-99质量份的正极活性物质、0.5-1质量份的第二导电剂和0.5-10质量份的第二粘结剂，均匀混合后，得到正极活性物质层浆料；
3)将步骤1)的热敏涂层浆料或步骤2)的正极活性物质层浆料依次交替地涂布在正极集流体表面，经过80-110℃干燥12-72小时后，得到所述正极极片。
根据本发明，所述溶剂选自N-甲基吡咯烷酮、氢氟醚、丙酮、四氢呋喃、二氯甲烷、吡啶中的至少一种。
根据本发明，步骤1)具体包括如下步骤：
1)将200-1000质量份溶剂、5-90质量份第一正极活性物质、2.9-40质量份第一导电剂、2-20质量份第一粘结剂中的油系粘结剂以及0.1-5质量份助剂，均匀混合后且过100目筛网，加入5-90质量份热敏聚合物微球均匀混合后，过100目筛网，得到热敏涂层浆料。
根据本发明，步骤3)具体包括如下步骤：
将N层热敏涂层和M层正极活性物质层按照顺序依次交替地涂布在正极集流体表面，且涂布完热敏涂层和正极活性物质层之后分别进行干燥。
有益效果
本发明提供一种多层复合正极极片及含该正极极片的二次电池。所述多层复合正极极片包括正极集流体、至少一层热敏涂层、至少一层复合融合层和至少一层正极活性物质层；所述正极集流体表面依次设置热敏涂层和正极活性物质层，且热敏涂层和正极活性物质层之间设置复合融合层；所述热敏涂层包括第一导电剂、第一粘结剂、第一正极活性物质、热敏聚合物微球和助剂，所述热敏涂层在常温下具有导电性能，同时具有增大活性物质与集流体间的接触面积、有效降低电池极化等优点；所述热敏涂层中引入第一正极活性物质，既保持了正极极片的高安全性，又提高了正极极片中的整体活性 物质含量，提升电池整体能量密度；当所述正极极片的使用温度达到热敏温度及其以上温度时，热敏聚合物微球会熔融形成至少一个连续电子阻隔层，涂层形成电流阻断，在电池内部形成内部阻断，防止二次电池进一步热失控的发生，提高二次电池安全性能。
附图说明
图1为本发明的正极极片的常温结构示意图。
图2为本发明的正极极片的高温结构示意图。
图3为实施例10、对比例1-2的正极极片的电阻随着温度升高，电阻数值的变化曲线。
图4为实施例10和对比例1-2制备的电池ARC测试结果。
具体实施方式
下文将结合具体实施例对本发明做更进一步的详细说明。应当理解，下列实施例仅为示例性地说明和解释本发明，而不应被解释为对本发明保护范围的限制。凡基于本发明上述内容所实现的技术均涵盖在本发明旨在保护的范围内。
下述实施例中所使用的实验方法如无特殊说明，均为常规方法；下述实施例中所用的试剂、材料等，如无特殊说明，均可从商业途径得到。
下述实施例中所使用的热敏聚合物微球全部购买于商业途径。
在本发明的描述中，需要说明的是，术语“第一”、“第二”等仅用于描述目的，而并非指示或暗示相对重要性。
实施例1
S1：配制热敏涂层浆料：将1000g N-甲基吡咯烷酮、26g钴酸锂、13g碳纳米管、15g聚偏氟乙烯、以及7g磷酸三乙酯均匀混合过100目筛网后，加入39g聚乙烯热敏聚合物微球，均匀混合后过100目筛网，得到热敏涂层浆料；
S2：配制正极浆料：将1000g N-甲基吡咯烷酮、99g钴酸锂、0.5g聚偏氟乙烯、0.5g碳纳米管均匀混合后，得到正极涂层浆料；
S3：制备正极极片：将S1中热敏涂层浆料涂布在铝箔集流体表面，经过110℃干燥12小时后，得到表面含有热敏涂层(记为第一层)的集流体；将S2 中正极涂层浆料涂覆在表面含有热敏涂层的集流体表面，经过110℃干燥12小时后、压片、剪裁处理后得到表面含有正极活性物质层(记为第二层)、热敏涂层(记为第一层)的正极极片，其中，热敏涂层和正极活性物质层在烘干、压片过程中互相渗透形成了复合融合层，通过扫描电镜和EDS能谱分析可以观察到复合融合层的厚度；
S4：制备负极极片：将400g去离子水、97g石墨、0.5g导电炭黑、1gCMC、1.5g丁苯橡胶，均匀混合后，涂布在负极集流体上，并经过干燥，干燥工艺属于业内常规工艺；
S5：制备锂离子电池：将正极、负极、隔膜采用叠片或卷绕等方法，制备锂离子电池电芯，经烘烤、注液、化成、封装后得到高安全锂离子电池。
实施例2-12以及对比例1-2
实施例2-12以及对比例1-2的制备过程同实施例1，均是材料多层涂布的方法制备得到的，区别在于步骤S1的热敏涂层浆料的组成不同，步骤S2的正极浆料的组成不同，以及步骤S3中的涂覆在正极集流体表面的浆料的顺序不同，具体如表1-2所示，其中，与正极集流体直接接触的一层记为第一层，依次记为第二层、第三层、……等等。
具体的，实施例2、实施例4、实施例5的电池是采用叠片式制备，实施例1、实施例3、实施例6-12和对比例1-2的电池采用卷绕式制备。
二、实验数据
极片电阻测试：采用ACCFILM膜片电阻测试仪器，该仪器采用可控压双探头电阻直接测试极片的整体电阻，输出的测量值为极片电阻。
测试过程为：通过对探头进行合适的表面平整度，加压10N，进行测试。将该测试装置置于烘箱中，烘箱初始温度20℃，以2℃/min的升温速率，升温至145℃，并实时记录数据。
交流阻抗测试电池内阻方法：采用Metrohm瑞士万通PGSTAT302N化学工作站在100KHz-0.1mHz范围，25℃条件下，对锂离子电池进行交流阻抗测试；
电池循环性能测试方法：锂离子电池在蓝电电池充放电测试柜上进行充 放电循环测试，测试条件为25℃、50％湿度、1C/1C充放电。
电池热测试方法：采用英国HEL品牌-PhiTEC I(ARC)型号绝热加速量热仪对电池在不同温度中的状态进行检测。
表1实施例1-12和对比例1-2中热敏涂层浆料的加入量及烘干条件
Figure PCTCN2021094177-appb-000001
表2实施例1-12和对比例1-2中热敏涂层浆料的组成
Figure PCTCN2021094177-appb-000002
Figure PCTCN2021094177-appb-000003
Figure PCTCN2021094177-appb-000004
表3 实施例1-12和对比例1-2中正极极片的结构
Figure PCTCN2021094177-appb-000005
1、极片电阻测试结果：图3为实施例10、对比例1、对比例2的正极极片的电阻随着温度升高，电阻数值的变化曲线：从图3中可以看出，通过对比实施例10和对比例1、对比例2正极极片的电阻测试结果，发现对比例1和对比例2的正极极片在20-140℃整个温度范围内，极片电阻稍微下降；实施例10正极极片在20℃-115℃内，正极极片电阻随温度的变化较小，在115℃-125℃内，随着正极极片中的热敏聚合物微球会熔融形成多个连续电子阻隔层，涂层形 成电流阻断，电阻呈数量级增加，这可以阻断离子和电子通过，改善电池安全性能。
2、对实施例1-12和对比例1-2制备的电池进行EIS测试和电池循环性能测试，测试结果如下：
Figure PCTCN2021094177-appb-000006
通过对比实施例1-12和对比例1-2制备的电池EIS测试结果，发现：
1)实施例1-12制备的电池中，正极极片中的正极层厚度增加，电池内阻随之增加。主要原因是极片增厚，导致锂离子、电子传输路径增加，电池阻抗增加，导致电池有效循环下降。但是实施例1-12制备的电池的内阻及循环性能，满足常规项目需求；
2)实施例10-12制备的电池中：实施例10-11的正极极片中正极层厚度不同，正层极极片中的正极层增加10μm，极片内部锂离子、电子传输路径增加，电池阻抗增加电池性能有所下降，实施例10电池1320次循环(容量保持80％)，实施例11电池1060次循环(容量保持80％)，基本满足客户需求；实施例10和实施例12的正极极片中热敏涂层厚度不同，实施例12与实施例10相比热敏涂层厚度降低2μm，实施例10电池1320次循环(容量保持80％)，实施例12电池1370次循环(容量保持80％)，对电池性能影响较小，属于正常范围内；
3)实施例10、实施例12、对比例1、对比例2实验结果：
电池内阻：对比例1(52.71mΩ)<实施例12(54.42mΩ)<实施例10(55.35mΩ)<对比例2(56.14mΩ)。实施例10、实施例12、对比例1、对比例2中正极活性物质厚度一样，区别在于：是否含有热敏涂层、涂层厚度。主要原因是对比例1中无正极底涂层，导致电池内阻稍小，对电池性能影响较小；
电池循环次数：实施例10电池1320次循环(容量保持80％)，实施例12电池1370次循环(容量保持80％)，对比例1电池1120次循环(容量保持80％)，对比例2电池1250次循环(容量保持80％)，主要原因是对比例1中无正极底涂，虽然前期电池内阻稍小，但是随着电池的循环，电池极化、动态内阻增加、正极不均一等因素，影响电池循环。
通过对比实施例1-12和对比例1-2制备的电池循环性能测试结果，发现本发明中的正极极片中的功能安全涂层，具有抑制电池极化、改善正极的一致性，提升电池的循环寿命特性；
3、采用英国HEL品牌-PhiTEC I(ARC)型号绝热加速量热仪对实施例10、对比例1-2中制备的电池进行测试，仪器内部以0.14℃/min速率进升温，并对电池的温度进行测试，测试结果如图4。通过对比实施例10和对比例1-2制备的电池ARC测试结果，发现对比例1-2的电池在175-185℃左右发生热失控，电池发生剧烈燃烧；实施例10的电池在195-205℃左右，发生热失控。
主要原因：电池从100℃升温至180℃期间，存在SEI膜破解、正极和电解液剧烈反应，尤其是在160℃-185℃区间内，会发生剧烈的热失控、起火等现象。实施例10的电池在110℃升温至185℃期间，在达到热敏温度时，电池内部形成阻隔层，阻断电池内部电路，延长电池安全时间，提高电池热失控温度。
实验结果说明，本发明的正极极片组装的二次电池较常规二次电池具有良好的安全性。
以上，对本发明的实施方式进行了说明。但是，本发明不限定于上述实施方式。凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种多层复合正极极片，其中，所述正极极片包括正极集流体、N层热敏涂层、P层复合融合层和M层正极活性物质层，其中，在正极集流体表面依次交替地设置所述N层热敏涂层和M层正极活性物质层，且热敏涂层和正极活性物质层之间设置复合融合层；N≥1，N+1≥M≥N-1，且M≥1，P＝N+M-1；
    所述热敏涂层包括热敏聚合物微球、第一正极活性物质、第一导电剂、第一粘结剂以及助剂；
    所述正极活性物质层包括第二正极活性物质、第二导电剂和第二粘结剂；
    所述复合融合层包括第一正极活性物质、第二正极活性物质、热敏聚合物微球、第一导电剂、第一粘结剂、第二导电剂、第二粘结剂以及助剂。
  2. 根据权利要求1所述的多层复合正极极片，其中，所述正极极片包括正极集流体、N层热敏涂层、P层复合融合层和M层正极活性物质层，其中，在正极集流体表面按照顺序依次交替地设置所述N层热敏涂层和M层正极活性物质层，且热敏涂层和正极活性物质层之间设置复合融合层；N≥1，N+1≥M≥N-1，且M≥1，P＝N+M-1；
    其中，所述顺序是如下中的一种：
    (1)正极集流体、热敏涂层、正极活性物质层、热敏涂层、正极活性物质层、……、热敏涂层、正极活性物质层；
    (2)正极集流体、热敏涂层、正极活性物质层、热敏涂层、正极活性物质层、……、热敏涂层、正极活性物质层、热敏涂层；
    (3)正极集流体、正极活性物质层、热敏涂层、正极活性物质层、热敏涂层、……、正极活性物质层、热敏涂层、正极活性物质层；
    (4)正极集流体、正极活性物质层、热敏涂层、正极活性物质层、热敏涂层、……、正极活性物质层、热敏涂层。
  3. 根据权利要求1或2所述的多层复合正极极片，其中，所述N层热敏涂层的组成相同或不同；
    所述热敏涂层包括如下重量百分含量的各组分：
    5-90wt％的热敏聚合物微球、5-90wt％的第一正极活性物质、2.9-40wt％的第一导电剂、2-20wt％的第一粘结剂以及0.1-5wt％的助剂。
  4. 根据权利要求1-3任一项所述的多层复合正极极片，其中，所述M层正 极活性物质层的组成相同或不同；
    所述正极活性物质层包括如下重量百分含量的各组分：
    80-99wt％的正极活性物质、0.5-10wt％的第二导电剂和0.5-10wt％的第二粘结剂。
  5. 根据权利要求1-4任一项所述的多层复合正极极片，其中，所述集流体的厚度为0.1μm-20μm；和/或，所述热敏涂层的厚度为0.1μm-5μm；和/或，所述复合融合层的厚度为0.001-0.5μm；和/或，所述正极活性物质层的厚度为5-175μm。
  6. 根据权利要求1-5任一项所述的多层复合正极极片，其中，所述热敏聚合物微球颗粒大小为100nm-3.0μm。
  7. 根据权利要求1-6任一项所述的多层复合正极极片，其中，所述正极极片的电阻为<10Ω。
  8. 根据权利要求1-7任一项所述的多层复合正极极片，其中，所述正极极片的厚度为50-200μm。
  9. 一种二次电池，所述二次电池包括权利要求1-8任一项所述的正极极片。
  10. 根据权利要求9所述的二次电池，其中，所述二次电池在25℃、1C/1C充放电制度下容量保持率降至80％时，循环的次数为大于等于1100次。
PCT/CN2021/094177 2020-05-29 2021-05-17 一种多层复合正极极片及含有该极片的二次电池 WO2021238709A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US18/070,172 US20230089391A1 (en) 2020-05-29 2022-11-28 Positive electrode plate and battery

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202010479706.6A CN113764613A (zh) 2020-05-29 2020-05-29 一种多层复合正极极片及含有该极片的二次电池
CN202010479706.6 2020-05-29

Related Child Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2021/094176 Continuation-In-Part WO2021238708A1 (zh) 2020-05-29 2021-05-17 一种含有高安全性热敏涂层的正极极片及锂离子电池

Publications (1)

Publication Number Publication Date
WO2021238709A1 true WO2021238709A1 (zh) 2021-12-02

Family

ID=78745761

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2021/094177 WO2021238709A1 (zh) 2020-05-29 2021-05-17 一种多层复合正极极片及含有该极片的二次电池

Country Status (2)

Country Link
CN (1) CN113764613A (zh)
WO (1) WO2021238709A1 (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115832188A (zh) * 2022-07-22 2023-03-21 宁德时代新能源科技股份有限公司 极片、电池单体、电池和用电装置及极片制造方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114759160B (zh) * 2022-05-05 2022-11-15 河南固锂电技术有限公司 一种高倍率性能的梯度钠离子电池正极材料及其制备方法

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101471435A (zh) * 2007-12-25 2009-07-01 比亚迪股份有限公司 锂离子二次电池正极及包括该正极的锂离子二次电池
CN107004858A (zh) * 2014-12-16 2017-08-01 株式会社Lg化学 含有ptc材料的二次电池电极的制造方法和由此方法制造的电极
JP2018026261A (ja) * 2016-08-10 2018-02-15 トヨタ自動車株式会社 非水電解質二次電池
CN109326819A (zh) * 2018-11-07 2019-02-12 江西迪比科股份有限公司 一种高安全性锂离子二次电池
CN109755468A (zh) * 2017-11-08 2019-05-14 宁德时代新能源科技股份有限公司 一种电极极片、电化学装置及安全涂层
CN109755464A (zh) * 2017-11-08 2019-05-14 宁德时代新能源科技股份有限公司 一种电极极片、电化学装置及安全涂层
CN109755466A (zh) * 2017-11-08 2019-05-14 宁德时代新能源科技股份有限公司 一种正极极片、电化学装置及安全涂层
CN110416490A (zh) * 2019-07-27 2019-11-05 珠海冠宇电池有限公司 一种兼顾能量密度的可提供双重安全保护的锂离子电池正极片
CN110890521A (zh) * 2019-11-13 2020-03-17 星恒电源股份有限公司 一种高能量高安全性能锂离子电池

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN203218375U (zh) * 2013-04-19 2013-09-25 宁德新能源科技有限公司 锂离子电池极片及锂离子电池
KR102628821B1 (ko) * 2015-12-28 2024-01-23 니폰 제온 가부시키가이샤 리튬 이온 이차 전지용 감열층
KR102207426B1 (ko) * 2016-12-07 2021-01-26 주식회사 엘지화학 고분자가 가교된 ptc층을 포함하는 이차전지용 전극 및 이의 제조방법
JP2018206734A (ja) * 2017-06-09 2018-12-27 三井化学株式会社 リチウムイオン二次電池及びその製造方法

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101471435A (zh) * 2007-12-25 2009-07-01 比亚迪股份有限公司 锂离子二次电池正极及包括该正极的锂离子二次电池
CN107004858A (zh) * 2014-12-16 2017-08-01 株式会社Lg化学 含有ptc材料的二次电池电极的制造方法和由此方法制造的电极
JP2018026261A (ja) * 2016-08-10 2018-02-15 トヨタ自動車株式会社 非水電解質二次電池
CN109755468A (zh) * 2017-11-08 2019-05-14 宁德时代新能源科技股份有限公司 一种电极极片、电化学装置及安全涂层
CN109755464A (zh) * 2017-11-08 2019-05-14 宁德时代新能源科技股份有限公司 一种电极极片、电化学装置及安全涂层
CN109755466A (zh) * 2017-11-08 2019-05-14 宁德时代新能源科技股份有限公司 一种正极极片、电化学装置及安全涂层
CN109326819A (zh) * 2018-11-07 2019-02-12 江西迪比科股份有限公司 一种高安全性锂离子二次电池
CN110416490A (zh) * 2019-07-27 2019-11-05 珠海冠宇电池有限公司 一种兼顾能量密度的可提供双重安全保护的锂离子电池正极片
CN110890521A (zh) * 2019-11-13 2020-03-17 星恒电源股份有限公司 一种高能量高安全性能锂离子电池

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115832188A (zh) * 2022-07-22 2023-03-21 宁德时代新能源科技股份有限公司 极片、电池单体、电池和用电装置及极片制造方法

Also Published As

Publication number Publication date
CN113764613A (zh) 2021-12-07

Similar Documents

Publication Publication Date Title
US10109863B2 (en) Composite binder composition for secondary battery, cathode and lithium battery containing the binder composition
CN114122320B (zh) 电极片及电化学装置
US20160104877A1 (en) Electrode with porous protective film , nonaqueous electrolyte secondary battery, and method for manufacturing electrode with porous protective film
WO2022037092A1 (zh) 一种集流体、极片和电池
WO2021238708A1 (zh) 一种含有高安全性热敏涂层的正极极片及锂离子电池
TW201214846A (en) Negative electrode for secondary battery, and process for production thereof
CN111916663B (zh) 一种正极极片及包括该正极极片的锂离子电池
WO2021238709A1 (zh) 一种多层复合正极极片及含有该极片的二次电池
WO2023155604A1 (zh) 复合隔膜及电化学装置
WO2022205163A1 (zh) 隔离膜及包含该隔离膜的电化学装置和电子装置
WO2022205165A1 (zh) 一种隔离膜及包含所述隔离膜的电化学装置和电子装置
KR20200056136A (ko) 전고체 이차전지 및 이의 제작방법
WO2023093506A1 (zh) 极片及电化学装置
WO2023093505A1 (zh) 极片及电化学装置
KR20230029832A (ko) 전극시트 및 배터리
JP7282925B2 (ja) リチウム二次電池用正極、その製造方法、及びそれを含むリチウム二次電池
JPWO2019044491A1 (ja) 蓄電デバイス用電極及びその製造方法
WO2022156459A1 (zh) 锂离子电池的负极片、锂离子电池和电子设备
WO2024032162A1 (zh) 一种电池隔膜和电池
WO2022016378A1 (zh) 电池及电子装置
US20230124048A1 (en) Positive electrode plate and lithium-ion battery including the positive electrode plate
WO2023185299A1 (zh) 正极极片、二次电池及用电装置
CN115036458B (zh) 一种锂离子电池
US10873089B2 (en) Positive electrode material and lithium secondary battery using the same
CN114824260A (zh) 一种安全锂离子电池

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21811768

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

32PN Ep: public notification in the ep bulletin as address of the adressee cannot be established

Free format text: NOTING OF LOSS OF RIGHTS PURSUANT TO RULE 112(1) EPC (EPO FORM 1205A DATED 17.03.2023)

122 Ep: pct application non-entry in european phase

Ref document number: 21811768

Country of ref document: EP

Kind code of ref document: A1