WO2020238521A1 - 正极集流体、正极极片、电化学装置和包含该电化学装置的用电设备 - Google Patents

正极集流体、正极极片、电化学装置和包含该电化学装置的用电设备 Download PDF

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WO2020238521A1
WO2020238521A1 PCT/CN2020/086974 CN2020086974W WO2020238521A1 WO 2020238521 A1 WO2020238521 A1 WO 2020238521A1 CN 2020086974 W CN2020086974 W CN 2020086974W WO 2020238521 A1 WO2020238521 A1 WO 2020238521A1
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blocking activation
positive electrode
layer
current collector
overcharge
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PCT/CN2020/086974
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English (en)
French (fr)
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於洋
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宁德时代新能源科技股份有限公司
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Priority to ES20814019T priority Critical patent/ES2928725T3/es
Priority to EP20814019.4A priority patent/EP3809502B1/en
Publication of WO2020238521A1 publication Critical patent/WO2020238521A1/zh
Priority to US17/149,736 priority patent/US11158859B2/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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
    • 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
    • H01M4/136—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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/668—Composites of electroconductive material and synthetic resins
    • 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

Definitions

  • This application belongs to the technical field of energy storage devices, and specifically relates to a positive electrode current collector, a positive electrode pole piece, an electrochemical device, and electrical equipment containing the electrochemical device.
  • Electrochemical devices represented by lithium ion secondary batteries mainly rely on the back-and-forth migration of active ions between the positive electrode active material and the negative electrode active material for charging and discharging. Electrochemical devices can provide stable voltage and current during use, and the use process is green and environmentally friendly, so they are widely used in various electrical equipment, such as mobile phones, tablet computers, notebook computers, electric bicycles, electric cars, etc.
  • the first aspect of the present application provides a positive electrode current collector, which includes: a metal conductive layer; an overcharge blocking activation layer, arranged on the surface of the metal conductive layer, the overcharge blocking activation layer includes an overcharge blocking activation material, adhesive Junction material and conductive material, wherein the overcharge blocking activation material includes esterified sugar.
  • a second aspect of the present application provides a positive electrode sheet, which includes the positive electrode current collector according to the first aspect of the present application; a positive electrode active material layer disposed on the surface of the positive electrode current collector whose overcharge blocking activation layer faces away from the metal conductive layer .
  • a third aspect of the present application provides an electrochemical device, which includes a positive pole piece, a negative pole piece, and a separator, wherein the positive pole piece is the positive pole piece according to the second aspect of the present application.
  • a fourth aspect of the present application provides an electrical equipment including the electrochemical device according to the third aspect of the present application.
  • the positive current collector provided by the embodiment of the present application includes a metal conductive layer and an overcharge blocking activation layer provided on the surface of the metal conductive layer.
  • the overcharge blocking activation layer includes an esterified sugar overcharge blocking activation material, so that When the electrochemical device is overcharged, the charging current can be cut off in time, effectively preventing the electrochemical device from thermal runaway, avoiding safety problems such as fire and explosion, and improving the overcharge safety performance of the electrochemical device.
  • the electrical equipment of the present application includes the electrochemical device, and therefore has at least the same advantages as the electrochemical device.
  • FIG. 1 is a schematic diagram of the structure of a positive electrode current collector in an embodiment of the present application.
  • FIG. 2 is a schematic diagram of the structure of a positive electrode current collector in another embodiment of the present application.
  • FIG. 3 is a schematic diagram of the structure of a positive pole piece in an embodiment of the present application.
  • FIG. 4 is a schematic diagram of the structure of a positive pole piece in another embodiment of the present application.
  • FIG. 5 is a schematic diagram of the structure of a positive pole piece in another embodiment of the present application.
  • Fig. 6 is a schematic diagram of an embodiment of a lithium ion battery.
  • Fig. 7 is an exploded view of Fig. 6.
  • Fig. 8 is a schematic diagram of an embodiment of a battery module.
  • Fig. 9 is a schematic diagram of an embodiment of a battery pack.
  • Fig. 10 is an exploded view of Fig. 9.
  • FIG. 11 is a schematic diagram of an embodiment of an electric device in which a lithium ion battery is used as a power source.
  • FIG. 12 is a graph of voltage-temperature-time of the lithium ion secondary battery of Example 1.
  • FIG. 13 is a voltage-temperature-time graph of the lithium ion secondary battery of Comparative Example 1.
  • any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and any upper limit may be combined with any other upper limit to form an unspecified range.
  • every point or single value between the end points of the range is included in the range. Therefore, each point or single numerical value can be used as its own lower limit or upper limit in combination with any other point or single numerical value or in combination with other lower or upper limits to form an unspecified range.
  • the embodiment of the present application provides a positive electrode current collector that can improve the overcharge safety performance of an electrochemical device.
  • Fig. 1 and Fig. 2 respectively provide a positive electrode current collector 10 as an example. 1 and 2, the positive electrode current collector 10 includes a metal conductive layer 101 and an overcharge blocking activation layer 102 provided on the surface of the metal conductive layer 101.
  • the overcharge blocking activation layer 102 may be disposed on either of the two opposite surfaces of the metal conductive layer 101 in the thickness direction (as shown in FIG. 1), or may be disposed on the two opposite surfaces of the metal conductive layer 101. On the surface ( Figure 2).
  • the overcharge blocking activation layer 102 includes an overcharge blocking activation material, an adhesive material and a conductive material, wherein the overcharge blocking activation material includes an esterified sugar.
  • an overcharge blocking activation layer 102 is provided on the surface of the metal conductive layer 101, and the overcharge blocking activation layer 102 includes esterified sugars, an overcharge blocking activation material and a binding material. And conductive materials. Under the normal working environment of the electrochemical device, the physical and chemical properties of the esterified sugar overcharge blocking activation material are stable, and the conductive material forms a continuous conductive network, so that the overcharge blocking activation layer 102 has a small resistance and ensures The positive electrode current collector 10 has good electrical conductivity.
  • the overcharge blocking activation material of the esterified sugar can undergo a chemical reaction under the conditions of high temperature ( ⁇ 60°C) and high voltage ( ⁇ 4.8V, relative to the lithium metal potential), thereby causing the material
  • the physical structure change of the overcharge blocking activation layer 102 will cause the conductive material particles in the overcharge blocking activation layer 102 to separate, causing the conductive network to break and destroy, and the resistance of the overcharge blocking activation layer 102 will increase sharply, thereby cutting off the charging current in time. Effectively prevent thermal runaway of electrochemical devices, avoid safety problems such as fire and explosion, and improve the overcharge safety performance of electrochemical devices.
  • the overcharge blocking activation layer 102 does not achieve the purpose of disconnecting the conductive network and cutting off the charging current through the crystallinity change of the overcharge blocking activation material at high temperature to cause volume expansion.
  • the overcharge blocking activation layer 102 has high reliability, as long as the temperature and voltage of the overcharge blocking activation layer 102 reach the above-mentioned threshold (ie temperature ⁇ 60°C; voltage ⁇ 4.8V, relative to the lithium metal potential), The rapid chemical reaction causes the conductive network to be broken and destroyed, and the charging current is cut off in time. For materials that rely on changes in crystallinity to cause volume expansion, they only undergo physical changes under high temperature conditions.
  • the sugar ring of the esterified sugar has an ester group, that is, more than one secondary hydroxyl group on the sugar ring of the sugar is esterified.
  • the inventor’s intensive research found that, compared with the ester group on the side chain of the sugar ring, the esterified sugar with the ester group on the sugar ring is more resistant to high temperature ( ⁇ 60°C) and high voltage ( ⁇ 4.8V, compared with lithium Metal potential) has a high response sensitivity, so that when the electrochemical device is overcharged, the overcharge blocking activation layer 102 can respond quickly, cut off the charging current, and better improve the overcharge safety performance of the electrochemical device.
  • the esterified sugar may be one or more of mono-esterified sugar and poly-esterified sugar.
  • Monoesterified sugars that is, monoesterified products of sugars, refer to products in which a hydrogen atom of a hydroxyl group of a sugar is replaced by an acyl group, and preferably includes a product in which a secondary hydroxyl group on the sugar ring of a sugar is replaced by an acyl group.
  • Polyesterified sugars that is, polyesterified products of sugars, refer to products in which the hydrogen atoms of more than two hydroxyl groups of the sugar are replaced by acyl groups, and preferably the product has an ester group on the sugar ring.
  • the esterified sugar includes a sugar esterification product in which more than two hydroxyl groups are esterified and a predetermined amount of hydroxyl groups is retained.
  • the residual hydroxyl groups in the esterified sugar can promote the activation of the overcharge blocking activation material of the esterified sugar, block the overcharge current in time, and improve the safety and reliability of overcharge.
  • the aforementioned predetermined amount of hydroxyl groups includes hydroxyl groups located on the sugar ring.
  • the sugar forms the sugar moiety of the esterified sugar after monoesterification or polyesterification.
  • the sugar can be one or more of monosaccharides, oligosaccharides, polysaccharides, amino sugars, sugar alcohols, deoxysugars and uronic acids, for example one of monosaccharides, oligosaccharides and polysaccharides One or more, for example one or more of oligosaccharide and polysaccharide.
  • Monosaccharides include, for example, one or more of ribose, xylose, galactose, mannose, glucose, and fructose.
  • Oligosaccharides contain 2-10 monosaccharide units, such as maltose, lactose, sucrose, oligosaccharides with a degree of polymerization of 2-10, maltotriose, maltotetraose, maltopentaose, maltohexaose, isomaltose , One or more of isomaltotriose, panose, mannotriose, and cyclodextrin containing less than or equal to 10 monosaccharide units.
  • the cyclodextrin containing less than or equal to 10 monosaccharide units is, for example, one or more of ⁇ -cyclodextrin, ⁇ -cyclodextrin, and ⁇ -cyclodextrin.
  • the polysaccharide contains more than 10 monosaccharide units, preferably more than 10 and less than or equal to 500 monosaccharide units.
  • Polysaccharides include, for example, one or more of starch, cellulose, chitosan, and cyclodextrin containing more than 10 monosaccharide units.
  • the amino sugar is, for example, a sugar obtained by substituting part of the hydroxyl groups on the above-mentioned monosaccharides, oligosaccharides, and polysaccharides with amino groups, and the number of the aforementioned parts is 1 or more.
  • the sugar alcohol is, for example, sorbitol, mannitol, maltitol, lactitol, xylitol, and the like.
  • Deoxysaccharides are, for example, sugars in which part of the hydroxyl groups on the above-mentioned monosaccharides, oligosaccharides, and polysaccharides are replaced by hydrogen atoms, and the number of the aforementioned parts is 1 or more.
  • Uronic acid is, for example, a sugar obtained by oxidizing primary hydroxyl groups on the above-mentioned monosaccharides, oligosaccharides, and polysaccharides to carboxyl groups.
  • the sugar is selected from one or more of glucose, oligosaccharides, cyclodextrin, cellulose, and chitosan. More preferably, the sugar is selected from glucose, oligosaccharides with a degree of polymerization of 2 to 10, cyclodextrins containing 6 to 10 monosaccharide units, cellulose with a degree of polymerization of 10 to 500, and a degree of polymerization of 10 to 500 One or more of the chitosan.
  • the acyl group preferably includes one or more of the acyl groups represented by formula 1 to formula 6:
  • R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 are each independently a hydrogen atom, an unsaturated aliphatic group, a saturated aliphatic group or an aromatic group, and R 8 is -(CH 2 ) n -, 0 ⁇ n ⁇ 8.
  • Unsaturated aliphatic groups include chain unsaturated aliphatic groups and cyclic aliphatic groups, such as chain or cyclic olefin groups having 2 to 12 carbon atoms, chain or cyclic groups having 2 to 12 carbon atoms Shape alkyne group.
  • it is selected from vinyl, 1-propenyl, 2-methylpropenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-propynyl, 2-propynyl, Cyclobutenyl, cyclopentenyl, cyclohexenyl.
  • the saturated aliphatic group includes a chain saturated aliphatic acyl group and a cyclic saturated aliphatic acyl group.
  • the chain saturated aliphatic acyl group is, for example, a linear or branched alkyl group having 1 to 12 carbon atoms, such as selected from methyl, Ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl and its isomers, etc.
  • the cyclic saturated aliphatic acyl group has, for example, 3-15 carbon atoms
  • Cyclic alkyl groups with or without side chains are selected from cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like.
  • the aromatic group is selected from, for example, 1-benzyl, 1-phenethyl, and the like.
  • n 1, 2, 3, 4, 5, 6, for example.
  • the acyl group is selected from one or more of Formula 1, Formula 2 and Formula 5.
  • the acyl group is more preferably Formula 2, that is, carbonate esterified sugars are preferred.
  • R 1 is selected from a methyl group, an ethyl group, a propyl group, and an isopropyl group
  • R 2 , R 5 , and R 6 are each independently a hydrogen atom, a methyl group, an ethyl group, a propyl group, and an isopropyl group.
  • Esterified sugars with these acyl groups have better reactivity under high temperature ( ⁇ 60°C) and high voltage ( ⁇ 4.8V, relative to lithium metal potential) conditions, and have higher reactivity when electrochemical devices are overcharged
  • the response sensitivity of the overcharge blocking activation layer 102 quickly responds, cuts off the charging current, and further improves the overcharge safety performance of the electrochemical device.
  • the donor of the acyl group may be the corresponding carboxylic acid, oxygen-containing inorganic acid, acid halide, acid anhydride, carbonate, sulfonate or phosphate.
  • the acid halide is, for example, an acid chloride.
  • the molar ratio of the sugar reaction substrate and the acyl donor can be controlled to generally ensure that the sugar ring of the esterified sugar retains a predetermined amount of hydroxyl groups.
  • the overcharge blocking activating material may include one or more of monosaccharides, oligosaccharides, and polysaccharides. Further, the overcharge blocking activation material may include one or more of poly-esterified products of oligosaccharides and poly-esterified products of polysaccharides. Furthermore, the multi-esterification products are preferably carbonates. Furthermore, the polyesterification product contains a predetermined amount of sugar ring hydroxyl groups.
  • the overcharge blocking activation material can be selected from glucose pentaacetate, glucose-1,6-diphosphate ethyl, glucose-1,6-dicarbonate, ⁇ -cyclodextrin acetate, ⁇ -Cyclodextrin carbonate, ⁇ -cyclodextrin phosphate, cellulose methyl carbonate, cellulose ethyl carbonate, cellulose methyl phosphate, cellulose ethyl phosphate, chitosan methyl carbonate, chitosan carbonate One or more of ethyl ester, chitosan methyl phosphate and chitosan ethyl phosphate.
  • the bonding material of the overcharge blocking activation layer 102 can be a bonding material with good high temperature resistance.
  • the binding material preferably includes polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyurethane, polyacrylonitrile (PAN), polyimide (PI), epoxy resin, organic One of silicone resin, ethylene-vinyl acetate copolymer (EVA), styrene-butadiene rubber (SBR), styrene-acrylic rubber, polyacrylic acid (PAA), acrylic acid-acrylate copolymer and ethylene-acrylate copolymer (EMA) Or multiple.
  • the bonding material has high thermal stability, which is beneficial to improve the stability of the overcharge blocking activation layer 102 in the normal operation of the electrochemical device; and can ensure the overcharge blocking activation layer 102 and the metal conductive layer 101 Has a high binding force.
  • the conductive material of the overcharge blocking activation layer 102 may include one or more of metal conductive materials, carbon-based conductive materials, and conductive polymer materials.
  • the metal conductive material includes, for example, one or more of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, and silver.
  • Carbon-based conductive materials include, for example, one or more of Ketjen black, mesophase carbon microspheres, activated carbon, graphite, conductive carbon black, acetylene black, carbon fibers, carbon nanotubes, and graphene.
  • the conductive polymer material includes, for example, one or more of polysulfur nitrides, aliphatic conjugated polymers, aromatic ring conjugated polymers, and aromatic heterocyclic conjugated polymers.
  • the aliphatic conjugated polymer is, for example, polyacetylene
  • the aromatic ring conjugated polymer is, for example, polyphenylene, polynaphthalene
  • the aromatic heterocyclic conjugated polymer is, for example, polypyrrole, polyacetylene, polyaniline, polythiophene, and polypyridine.
  • the mass percentage of the overcharge blocking activation material is 25%-45%, and the mass percentage of the bonding material is 35%-60%.
  • the mass percentage of the conductive material is 6%-20%.
  • the overcharge blocking activation layer 102 has a low resistance and can effectively improve the overcharge safety performance of the electrochemical device.
  • the mass percentage of the overcharge blocking activation material is 30%-40%, the mass percentage of the adhesive material is 45%-55%, and the mass percentage of the conductive material The percentage content is 6% to 10%.
  • the overcharge blocking activation layer 102 may further include auxiliary materials, and the auxiliary materials are materials that have good affinity for the overcharge blocking activation material, the adhesive material, and the conductive material.
  • auxiliary materials can improve the compatibility and affinity between the overcharge blocking activation material, the bonding material, and the conductive material, thereby improving the uniformity of the overcharge blocking activation material and the conductive material in the bonding material.
  • the flatness of the overcharge blocking activation layer 102 reduces defects such as pits in the layer, which can improve the overall protection effect of the overcharge blocking activation layer 102.
  • any point of the positive electrode current collector 10 will cause the overcharge blocking activating material to respond, preventing the leakage between the positive electrode active material layer 20 ( Figure 3 to Figure 5) and the metal conductive layer 101. Safety hazards coming.
  • the overcharge blocking activation material and the conductive material are uniformly dispersed in the bonding material, so that the conductive material forms a uniform and continuous conductive network, ensuring that the resistance of the overcharge blocking activation layer 102 is low during normal charging and discharging. , The performance of the electrochemical device (such as cycle performance) is better.
  • Auxiliary materials preferably include sodium carboxymethyl cellulose (CMC-Na), silane coupling agents (such as vinyltrimethoxysilane, etc.), titanate coupling agents, organopolysiloxanes, higher alcohol fatty acid esters One or more of compound, polyoxyethylene polyoxypropylene pentaerythritol ether, polyoxyethylene polyoxypropanol amine ether, polyoxypropylene glycerol ether, and polyoxypropylene polyoxyethylene glycerol ether.
  • the titanate coupling agent is, for example, bis(dioctyloxypyrophosphate) ethylene titanate.
  • the organopolysiloxane is, for example, emulsified silicone oil, and another example is polydimethylsiloxane.
  • the auxiliary material includes vinyl trimethoxysilane and/or polyoxypropylene glycerol ether.
  • the mass percentage content of the auxiliary material in the overcharge blocking activation layer 102 is preferably 1%-10%, more preferably 2%-8%, such as 5%.
  • the overcharge blocking activation layer 102 includes 3% vinyltrimethoxysilane and 2% polyoxypropylene glycerol ether.
  • the overcharge blocking activation layer 102 may only be provided on a single surface of the metal conductive layer 101.
  • the thickness of the overcharge blocking activation layer 102 is within the above range, so that the positive electrode current collector 10 has a smaller internal resistance, and can effectively play the role of the overcharge blocking activation layer 102 in improving the overcharge safety performance of the electrochemical device.
  • the thickness of the overcharge blocking activation layer 102 is within the above range, which is also beneficial to ensure that the electrochemical device has a lower volume and weight, so that it has a higher volume energy density and a higher weight energy density.
  • d may be 2 ⁇ m to 7 ⁇ m.
  • d may be 3 ⁇ m to 5 ⁇ m.
  • the thickness of the overcharge blocking activation layer 102 is within the above range, so that the positive electrode current collector 10 has a smaller internal resistance, and can effectively play the role of the overcharge blocking activation layer 102 in improving the overcharge safety performance of the electrochemical device.
  • the thickness of the overcharge blocking activation layer 102 is within the above range, which is also beneficial to ensure that the electrochemical device has a lower volume and weight, so that it has a higher volume energy density and a higher weight energy density.
  • an overcharge blocking activation layer 102 containing an overcharge blocking activation material is provided on all surfaces of the metal conductive layer 101 where the positive electrode active material layer 20 needs to be disposed. In this way, it is possible to achieve higher repeatability and reliability of the current blocking effect while further improving the overcharge safety performance of the electrochemical device.
  • the thickness D of the metal conductive layer 101 is not particularly limited, and can be selected according to actual requirements.
  • the metal conductive layer 101 may be a metal foil or a metal plate with good electrical conductivity and mechanical properties.
  • the metal conductive layer 101 may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, and preferably includes one or more of aluminum and aluminum alloy.
  • the weight percentage of the aluminum element in the aluminum alloy is preferably 80% to 100%, more preferably 90% or more.
  • the aluminum alloy is, for example, aluminum-zirconium alloy.
  • the metal conductive layer 101 may be aluminum foil.
  • an embodiment of the present application provides a method for preparing the positive electrode current collector 10, by which any one of the above-mentioned positive electrode current collectors 10 can be prepared.
  • the method includes a production step S100 of overcharge blocking the active layer slurry and a production step S200 of a current collector.
  • S100 Disperse the overcharge blocking activation material, the adhesive material and the conductive material in a solvent according to a preset weight ratio to form a uniform overcharge blocking activation layer slurry.
  • the overcharge blocking activation material, the adhesive material and the conductive material can be the above-mentioned materials, which will not be repeated here.
  • the solvent is, for example, N-methylpyrrolidone (NMP).
  • the above-mentioned auxiliary materials can also be added.
  • the auxiliary material can improve the compatibility of the overcharge blocking activation material, the bonding material and the conductive material with each other, and play a defoaming effect, thereby improving the dispersion of the overcharge blocking activation material and the conductive material in the bonding material Uniformity, forming a more stable slurry.
  • the auxiliary material can also promote the full spread of the slurry on the surface of the metal conductive layer, improve the flatness of the overcharge blocking activation layer, and reduce defects such as pits in the layer.
  • the overall protection of the overcharge blocking activation layer is improved, so that when the electrochemical device is overcharged, any point of the positive electrode current collector will make the overcharge blocking activation material respond to prevent potential safety hazards caused by leakage.
  • the overcharge blocking activation material and the conductive material are evenly dispersed in the bonding material, so that the conductive material forms a uniform and continuous conductive network, ensuring that the overcharge blocking activation layer has a small resistance during the normal charge and discharge process , The performance of the electrochemical device is better.
  • a mixer can be used to mix the materials, and the materials are mixed uniformly through stirring to form a uniform slurry.
  • the mixer may be a known mixer for mixing materials, such as a planetary mixer.
  • the vacuum degassing method can be further used to eliminate bubbles in the slurry, further improve the flatness of the overcharge blocking activation layer, and reduce defects such as pits in the layer.
  • step S200 a coating method known in the art can be used to sufficiently coat the overcharge blocking activation layer slurry on the surface of the metal conductive layer.
  • a coating method known in the art can be used to sufficiently coat the overcharge blocking activation layer slurry on the surface of the metal conductive layer. For example, using a gravure or micro-gravure coater can make the coating have a higher uniformity.
  • the drying may be natural air drying, infrared drying, or blast heating and drying under the conditions of 40°C to 120°C. For example, drying under hot air conditions at 60°C to 80°C.
  • the embodiment of the present application also provides a positive pole piece.
  • the positive pole piece includes a positive current collector 10 according to an embodiment of the present application and a positive active material layer 20 provided on the positive current collector 10. Since the positive pole piece of the embodiment of the present application adopts the positive current collector 10 of the embodiment of the present application, it also has corresponding advantages.
  • the positive electrode piece of the embodiment of the present application includes a positive electrode current collector 10 and a positive electrode active material layer 20 provided on at least one surface of the positive electrode current collector 10.
  • the positive electrode current collector 10 includes two opposite surfaces in its thickness direction, and the positive electrode active material layer 20 is disposed on the two surface sides, wherein the positive electrode active on at least one side
  • An overcharge blocking activation layer 102 is provided between the material layer 20 and the metal conductive layer 101.
  • an overcharge blocking activation layer 102 is provided between the positive electrode active material layer 20 and the metal conductive layer 101 on both sides.
  • the metal conductive layer 101 of the positive electrode current collector 10 may include two opposite surfaces in its thickness direction, and the overcharge blocking activation layer 102 is disposed on any of the two surfaces.
  • the positive electrode active material layer 20 is disposed on the surface of the overcharge blocking activation layer 102 facing away from the metal conductive layer 101.
  • the area of the overcharge blocking activation layer 102 is S 1
  • the area of the positive electrode active material layer 102 disposed on the surface of the overcharge blocking activation layer 102 facing away from the metal conductive layer 101 is S 2
  • the area The ratio is preferably 0.8 ⁇ S 1 /S 2 ⁇ 1 , more preferably 0.98 ⁇ S 1 /S 2 ⁇ 1 , and more preferably 0.99 ⁇ S 1 /S 2 ⁇ 1 .
  • the positive active material layer 20 includes a positive active material, which can be a positive active material capable of reversibly deintercalating active ions known in the art, and this application is not limited.
  • the positive electrode active material for lithium ion secondary batteries may include one or more of lithium transition metal composite oxides, lithium transition metal composite oxides and composite oxides obtained by adding other transition metals or non-transition metals or non-metals.
  • the transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce, and Mg.
  • the positive electrode active material may be selected from lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium-containing olivine structure
  • phosphates such as LiMn 2 O 4 , LiNiO 2 , LiCoO 2 , LiNi 1-y Co y O 2 (0 ⁇ y ⁇ 1), LiNi a Co b Al 1-ab O 2 (0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ a+b ⁇ 1), LiMn 1-mn Ni m Co n O 2 (0 ⁇ m ⁇ 1, 0 ⁇ n ⁇ 1, 0 ⁇ m+n ⁇ 1 ), LiMPO 4 (M can be one or more of Fe, Mn, and Co), and Li 3 V 2 (PO 4 ) 3 at one or more.
  • LiMn 1-mn Ni m Co n O 2 is, for example, LiMn 0.1 Ni 0.8 Co 0.1 O 2 , LiMn 0.3 Ni 0.5 Co 0.2 O 2 , LiMn 0.2 Ni 0.6 Co 0.2 O 2 , LiMn 1/3 Ni 1/3 Co 1/ 3 O 2 etc.
  • the positive active material layer 20 further includes a binder, and the embodiment of the present application does not limit the type of the binder.
  • the binder can be styrene butadiene rubber (SBR), water-based acrylic resin, sodium carboxymethyl cellulose (CMC-Na), polyvinylidene fluoride (PVDF), polytetrafluoroethylene One or more of (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).
  • the positive electrode active material layer 20 further includes a conductive agent, and the embodiment of the present application does not limit the type of the conductive agent.
  • the conductive agent may be one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive pole piece can be prepared according to conventional methods in the art.
  • the positive electrode active material, the conductive agent and the binder are dispersed in a solvent to form a uniform positive electrode slurry.
  • the solvent is, for example, N-methylpyrrolidone (NMP); the positive electrode slurry is coated on the positive electrode current collector 10. After drying, cold pressing and other processes, the positive pole piece is obtained.
  • NMP N-methylpyrrolidone
  • the embodiments of the present application also provide an electrochemical device.
  • the electrochemical device includes a positive pole piece, a separator and a negative pole piece, wherein the positive pole piece adopts the positive pole piece of the embodiment of the present application.
  • the electrochemical device of the embodiment of the present application adopts the positive pole piece of the embodiment of the present application, it also has corresponding advantages, such as higher overcharge safety performance, and more preferably includes the other beneficial effects mentioned above.
  • the electrochemical device can be a bare cell or a battery containing a bare cell and an electrolyte.
  • the battery is, for example, a secondary battery (such as a lithium ion secondary battery, a sodium ion battery, a magnesium ion battery, etc.), a primary battery (such as a lithium primary battery, etc.), but not limited thereto.
  • the bare cell can be a laminated structure formed by stacking positive pole pieces, separators, and negative pole pieces in order, or it can be a winding obtained by stacking positive pole pieces, separators, and negative pole pieces in order. Structure. Among them, the separator is located between the positive pole piece and the negative pole piece for isolation.
  • the negative pole piece may include a negative current collector and a negative active material layer provided on at least one surface of the negative current collector.
  • the anode active material layer is provided on either or both of the two opposite surfaces of the anode current collector in the thickness direction of the anode current collector.
  • the negative active material layer can be a negative active material known in the art that can perform reversible deintercalation of active ions, which is not limited in this application.
  • the negative electrode active material used in lithium ion secondary batteries may include metallic lithium, natural graphite, artificial graphite, mesophase micro-carbon spheres (abbreviated as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO x (0 ⁇ x ⁇ 2), one or more of Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , spinel structure lithium titanate, and Li-Al alloy.
  • metallic lithium natural graphite, artificial graphite, mesophase micro-carbon spheres (abbreviated as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO x (0 ⁇ x ⁇ 2), one or more of Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , spinel structure lithium titanate, and Li-Al alloy.
  • MCMB mesophase micro-carbon spheres
  • the negative electrode active material layer further includes a binder, and the embodiment of the present application does not limit the type of the binder.
  • the binder can be styrene butadiene rubber (SBR), water-based acrylic resin, sodium carboxymethyl cellulose (CMC-Na), polyvinylidene fluoride (PVDF), polytetrafluoroethylene One or more of (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA) and polyvinyl butyral (PVB).
  • the negative active material layer further includes a conductive agent, and the embodiment of the present application does not limit the type of the conductive agent.
  • the conductive agent may be one or more of graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the negative pole piece can be prepared according to conventional methods in the art.
  • the negative electrode active material, the conductive agent, and the binder can be dispersed in a solvent to form a uniform negative electrode slurry, such as deionized water; the negative electrode slurry is coated on the negative electrode current collector and dried, After the cold pressing and other processes, the negative pole piece is obtained.
  • isolation membranes do not specifically limit the types of isolation membranes, and can be any porous isolation membranes that can be used in electrochemical devices, such as glass fiber isolation membranes, non-woven isolation membranes, polyethylene isolation membranes, and polypropylene isolation membranes.
  • the electrolyte can be a solid electrolyte or a non-aqueous electrolyte. There are no specific restrictions on their types and can be selected according to needs.
  • the non-aqueous electrolyte includes an organic solvent and an electrolyte salt.
  • the organic solvent used in lithium ion secondary batteries can be selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF ), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate Ester (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulf
  • the electrolyte salt used in lithium ion secondary batteries can be selected from LiPF 6 (lithium hexafluorophosphate), LiBF 4 (lithium tetrafluoroborate), LiClO 4 (lithium perchlorate), LiAsF 6 (lithium hexafluoroarsenate), LiFSI ( Lithium bisfluorosulfonimide), LiTFSI (lithium bistrifluoromethanesulfonimide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalate), LiBOB (lithium bisoxalate), LiPO 2 F 2 (lithium difluorophosphate), LiDFOP (lithium difluorodioxalate phosphate), and LiTFOP (lithium tetrafluorooxalate phosphate) one or more, but not limited thereto.
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium te
  • the non-aqueous electrolyte may also optionally include additives to improve battery performance, and there is no specific limitation on the type of additives, which can be selected according to requirements.
  • the battery cell can be prepared according to methods known in the art.
  • the positive pole piece, the separator film and the negative pole piece are laminated in order, so that the separator film is located between the positive pole piece and the negative pole piece to isolate the battery cell, or it can be wound to obtain electricity. core.
  • the battery can be prepared according to methods known in the art. For example, placing the battery cell in an outer package, injecting non-aqueous electrolyte and sealing to obtain a battery.
  • the present application does not particularly limit the shape of the electrochemical device, which can be cylindrical, square or any other shape.
  • the electrochemical device is a secondary battery 5 with a square structure.
  • the secondary battery 5 may include an outer package for encapsulating the battery cell and the electrolyte.
  • the outer packaging of the secondary battery 5 may be a hard case, such as a hard plastic case, aluminum case, steel case, and the like.
  • the outer packaging of the secondary battery 5 may also be a soft bag, such as a pouch type soft bag.
  • the material of the soft bag can be plastic, for example, it can include one or more of polypropylene PP, polybutylene terephthalate PBT, polybutylene succinate PBS, and the like.
  • the outer package may include a housing 51 and a cover 53.
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the housing 51 has an opening communicating with the containing cavity, and a cover plate 53 can cover the opening to close the containing cavity.
  • the positive pole piece, the negative pole piece and the isolation film may be formed into the cell 52 through a lamination process or a winding process.
  • the battery core 52 is encapsulated in the containing cavity.
  • the electrolyte is infiltrated in the cell 52.
  • the number of battery cells 52 contained in the secondary battery 5 can be one or several, which can be adjusted according to requirements.
  • the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • FIG. 8 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in order along the length direction of the battery module 4. Of course, it can also be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having an accommodation space, and a plurality of secondary batteries 5 are accommodated in the accommodation space.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 provided in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3.
  • the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4.
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the embodiments of the present application also provide an electrical equipment, which includes the electrochemical device described in the present application.
  • the electrochemical device can be used as a power source of the electrical equipment, and can also be used as an energy storage unit of the electrical equipment.
  • the electrical equipment can be, but is not limited to, mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric Golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the electrical equipment can select an electrochemical device according to its usage requirements, such as a primary battery, a secondary battery, a battery module or a battery pack.
  • Figure 11 is an example of electrical equipment.
  • the electrical equipment is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • battery packs or battery modules can be used.
  • the power-consuming device may be a mobile phone, a tablet computer, a notebook computer, and the like.
  • the electrical equipment is generally required to be light and thin, and a secondary battery can be used as a power source.
  • Making slurry for overcharge blocking activation layer Take 53 parts by weight of polyvinylidene fluoride (PVDF), 7 parts of conductive carbon black (Super-P), 38 parts by weight of glucose pentaacetate, and 2 parts by weight of polyoxypropylene
  • PVDF polyvinylidene fluoride
  • Super-P conductive carbon black
  • glucose pentaacetate acetate
  • polyoxypropylene The glyceryl ether is placed in a planetary stirring tank, and 900 parts by weight of N-methylpyrrolidone (NMP) are added as a dispersing solvent, and the mixture is rapidly stirred for 5 hours to form a uniform and stable slurry.
  • NMP N-methylpyrrolidone
  • Making the positive electrode current collector vacuumize the above uniform and stable slurry to remove bubbles, and then use a gravure or micro-gravure coater to coat the surface of the metal conductive layer on the aluminum foil on both sides. After drying, a uniform and dense overcharge blocking is obtained
  • the active layer is used to prepare a positive electrode current collector, wherein the thickness of the aluminum foil of the metal conductive layer is 12 ⁇ m, and the thickness of the single-sided overcharge blocking activation layer is 3 ⁇ m.
  • the area S 1 of the overcharge blocking activation layer and the positive electrode active material layer The ratio S 1 /S 2 of the area S 2 is 1, and the coverage rate of the positive electrode active material layer by the overcharge blocking activation layer is 100%.
  • Ethylene carbonate (EC), propylene carbonate (PC) and dimethyl carbonate (DMC) are mixed uniformly in a weight ratio of 1:1:1 to obtain an organic solvent; then the lithium salt LiPF 6 is dissolved in the above organic In the solvent, mix uniformly to obtain an electrolyte, in which the concentration of LiPF 6 is 1 mol/L.
  • the positive pole piece, the polyethylene porous separation film, and the negative pole piece are laminated in order, and then wound to obtain a battery; the battery is placed in an outer package, electrolyte is injected and packaged to obtain a lithium ion secondary battery.
  • Example 1 The difference from Example 1 is that the overcharge blocking activation material is 34 parts by weight of glucose-1,6-diphosphate ethyl ester, the binding material is 53 parts by weight of PVDF, and the conductive material is 7 parts by weight of conductive carbon black (Super- P) and 1 part by weight of carbon nanotubes (CNT), and the auxiliary materials are 3 parts by weight of vinyl trimethoxysilane and 2 parts by weight of polyoxypropylene glyceryl ether.
  • the overcharge blocking activation material is 34 parts by weight of glucose-1,6-diphosphate ethyl ester
  • the binding material is 53 parts by weight of PVDF
  • the conductive material is 7 parts by weight of conductive carbon black (Super- P) and 1 part by weight of carbon nanotubes (CNT)
  • the auxiliary materials are 3 parts by weight of vinyl trimethoxysilane and 2 parts by weight of polyoxypropylene glyceryl ether.
  • Example 1 The difference from Example 1 is that the overcharge blocking activation material is 37 parts by weight of glucose-1,6-diphosphate methyl ester, the binding material is 52 parts by weight of PVDF, and the conductive material is 5 parts by weight of Super-P and 1 part by weight.
  • Parts of CNT, auxiliary materials are 3 parts by weight of vinyl trimethoxysilane and 2 parts by weight of polyoxypropylene glycerol ether.
  • Example 2 The difference from Example 1 is that the overcharge blocking activation material is 36 parts by weight of ⁇ -cyclodextrin acetate, the bonding material is 52 parts by weight of PVDF, the conductive material is 7 parts by weight of Super-P, and the auxiliary material is 3 parts. Parts by weight of vinyl trimethoxysilane and 2 parts by weight of polyoxypropylene glyceryl ether.
  • the thickness of the single-sided overcharge blocking activation layer is 2 ⁇ m.
  • Example 1 The difference from Example 1 is that the overcharge blocking activation material is 36 parts by weight of ⁇ -cyclodextrin carbonate, the binding material is 52 parts by weight of PVDF, the conductive material is 7 parts by weight of Super-P, and the auxiliary material is 3 parts by weight. Parts of vinyl trimethoxysilane and 2 parts by weight of polyoxypropylene glyceryl ether.
  • the thickness of the single-sided overcharge blocking activation layer is 5 ⁇ m.
  • Example 2 The difference from Example 1 is that the overcharge blocking activation material is 36 parts by weight of ⁇ -cyclodextrin phosphate, the binding material is 52 parts by weight of PVDF, the conductive material is 7 parts by weight of Super-P, and the auxiliary material is 3 parts by weight. Parts of vinyl trimethoxysilane and 2 parts by weight of polyoxypropylene glyceryl ether.
  • Example 8 The difference from Example 8 is that the thickness of the single-sided overcharge blocking activation layer is 7 ⁇ m.
  • Example 1 The difference from Example 1 is that the overcharge blocking activation material is 35 parts by weight of cellulose methyl carbonate, the binding material is 50 parts by weight of SBR, the conductive material is 10 parts by weight of Super-P, and the auxiliary material is 5 parts by weight of CMC. -Na, the dispersion solvent is deionized water.
  • Example 2 The difference from Example 1 is that the overcharge blocking activation material is 35 parts by weight of chitosan methyl carbonate, the binding material is 50 parts by weight of PVDF, the conductive material is 10 parts by weight of Super-P, and the auxiliary material is 3 parts by weight. Vinyltrimethoxysilane and 2 parts by weight of polyoxypropylene glyceryl ether.
  • Example 2 The difference from Example 1 is that the overcharge blocking activation material is 40 parts by weight of cellulose methyl carbonate, the binding material is 50 parts by weight of PVDF, and the conductive material is 8 parts by weight of Super-P and 2 parts by weight of CNT. Supplementary materials.
  • Example 2 The difference from Example 1 is that the overcharge blocking activation material is 35 parts by weight of cellulose methyl carbonate, the binding material is 53 parts by weight of PAA, the conductive material is 7 parts by weight of Super-P, and the auxiliary material is 3 parts by weight of ethylene. trimethoxysilane, and 2 parts by weight of polyoxypropylene glyceryl ether, the dispersion solvent is deionized water; the area on one side and a metallic conductive layer, an active layer over the charge blocking area S 1 and the positive electrode active material layer S 2 of The ratio S 1 /S 2 is 98%.
  • the overcharge blocking activation material is 35 parts by weight of cellulose methyl carbonate
  • the binding material is 53 parts by weight of PAA
  • the conductive material is 7 parts by weight of Super-P
  • the auxiliary material is 3 parts by weight of ethylene. trimethoxysilane, and 2 parts by weight of polyoxypropylene glyceryl ether
  • the dispersion solvent is deion
  • Example 2 The difference from Example 1 is that the overcharge blocking activation material is 35 parts by weight of cellulose methyl carbonate, the binding material is 53 parts by weight of PVDF, and the conductive material is 5 parts by weight of Super-P and 2 parts by weight of CNT. 3 parts by weight of vinyl trimethoxysilane and 2 parts by weight of polyoxypropylene glyceryl ether; and the thickness of the single-sided overcharge blocking activation layer is 0.5 ⁇ m.
  • Example 2 The difference from Example 1 is that the overcharge blocking activation material is 35 parts by weight of cellulose methyl carbonate, the binding material is 53 parts by weight of PVDF, the conductive material is 7 parts by weight of Super-P, and the auxiliary material is 3 parts by weight of ethylene. Trimethoxysilane and 2 parts by weight of polyoxypropylene glyceryl ether.
  • Example 5 The difference from Example 5 is that the slurry of the overcharge blocking activation layer is coated on the surface of the metal conductive layer aluminum foil, and after drying, a uniform and dense overcharge blocking activation layer is obtained, and the positive electrode current collector is prepared.
  • the thickness of the aluminum foil of the metal conductive layer is 12 ⁇ m, and the thickness of the overcharge blocking activation layer is 10 ⁇ m.
  • Example 2 The difference from Example 1 is that the overcharge blocking activation material is 35 parts by weight of cellulose methyl carbonate, the binding material is 53 parts by weight of PVDF, and the conductive material is 5 parts by weight of Super-P and 2 parts by weight of CNT. It is 3 parts by weight of vinyl trimethoxysilane and 2 parts by weight of polyoxypropylene glyceryl ether; and the positive electrode active material is LiCoO 2 .
  • Example 1 The difference from Example 1 is that the positive electrode current collector is a 12 ⁇ m thick aluminum foil, and no overcharge blocking activation layer is provided.
  • the positive electrode current collector includes a 12 ⁇ m thick aluminum foil conductive layer and coatings arranged on two opposite surfaces of the aluminum foil conductive layer;
  • the slurry for making the coating includes: taking 5 parts by weight of CMC-Na, 85 Parts by weight of SBR and 10 parts by weight of Super-P are placed in a planetary stirring tank, and then 900 parts by weight of deionized water are added as a dispersion solvent, and stirred rapidly for 5 hours to form a uniform and stable slurry.
  • the remaining steps are the same as in Example 1.
  • the positive electrode current collector includes a 12 ⁇ m thick aluminum foil conductive layer and coatings arranged on two opposite surfaces of the aluminum foil conductive layer;
  • the slurry for making the coating includes: 90 parts by weight of PAA and 10 parts by weight Super-P is placed in a planetary stirring tank, and then 900 parts by weight of deionized water is added as a dispersion solvent, and stirred rapidly for 5 hours to form a uniform and stable slurry.
  • the remaining steps are the same as in Example 1.
  • the positive electrode current collector includes a 12 ⁇ m thick aluminum foil conductive layer and coatings arranged on two opposite surfaces of the aluminum foil conductive layer;
  • the slurry for making the coating includes: taking 90 parts by weight of PVDF and 10 parts by weight Super-P is placed in a planetary stirring tank, and then 900 parts by weight of NMP is added as a dispersing solvent, and stirred rapidly for 5 hours to form a uniform and stable slurry.
  • the remaining steps are the same as in Example 1.
  • Example 17 The difference from Example 17 is that the positive electrode current collector is 12 ⁇ m thick aluminum foil, and no overcharge blocking activation layer is provided.
  • the positive electrode current collector includes a 12 ⁇ m thick aluminum foil conductive layer and coatings arranged on two opposite surfaces of the aluminum foil conductive layer;
  • the slurry for making the coating includes: 90 parts by weight of PVDF and 10 parts by weight Super-P is placed in a planetary stirring tank, and then 900 parts by weight of NMP is added as a dispersing solvent, and stirred rapidly for 5 hours to form a uniform and stable slurry.
  • the remaining steps are the same as in Example 14.
  • Cycle capacity retention rate (%) discharge capacity at the 100th cycle/discharge capacity at the first cycle ⁇ 100%
  • Fig. 13 is a voltage-temperature-time curve diagram of the lithium ion secondary battery of Comparative Example 1.
  • the battery temperature rises sharply, the battery becomes thermally out of control and fails, causing fire and explosion, causing safety risks.
  • Figure 12 is a voltage-temperature-time curve diagram of the lithium-ion secondary battery of Example 1.
  • the overcharge blocking activation layer can respond quickly to cut off the external charging current and suppress the battery temperature rise High, thereby significantly improving the battery's overcharge safety performance. It can be seen from the comparative analysis of FIG. 12 and FIG. 13 that by providing an overcharge blocking activation layer in the positive electrode current collector, the overcharge safety performance of the lithium-ion secondary battery is significantly improved.
  • Example 12 it can be seen from the results of Example 12 and Examples 13, 15 that by further adding auxiliary materials, the overcharge blocking activation layer can better improve the overcharge safety performance of the battery.

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Abstract

本申请公开了一种正极集流体、正极极片、电化学装置和包含该电化学装置的用电设备。正极集流体包括：金属导电层；过充阻断激活层，设置于金属导电层的表面，过充阻断激活层包括过充阻断激活材料、粘结材料和导电材料，其中过充阻断激活材料包括酯化糖。

Description

正极集流体、正极极片、电化学装置和包含该电化学装置的用电设备
相关申请的交叉引用
本申请要求享有于2019年05月24日提交的名称为“正极集流体、正极极片及电化学装置”的中国专利申请201910441399.X的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请属于储能装置技术领域，具体涉及一种正极集流体、正极极片、电化学装置和包含该电化学装置的用电设备。
背景技术
以锂离子二次电池为代表的电化学装置主要依靠活性离子在正极活性物质和负极活性物质之间的往返迁移来进行充电、放电。电化学装置在使用过程中能够提供稳定的电压和电流，且使用过程绿色环保，从而被广泛地应用于各类用电设备，如手机、平板电脑、笔记本电脑、电动自行车、电动汽车等。
电化学装置在造福人类的同时，其在充电过程中出现的起火和爆炸等安全问题也时有发生，给人们的生命和财产安全带来很大威胁。因此，如何提高电化学装置的过充安全性能成为亟待解决的技术问题。
发明内容
本申请的第一方面提供一种正极集流体，其包括：金属导电层；过充阻断激活层，设置于金属导电层的表面，过充阻断激活层包括过充阻断激活材料、粘结材料和导电材料，其中过充阻断激活材料包括酯化糖。
本申请的第二方面提供一种正极极片，其包括根据本申请第一方面的正极集流体；正极活性物质层，设置于正极集流体的过充阻断激活层背向金属导电层的表面。
本申请的第三方面提供一种电化学装置，其包括正极极片、负极极片及隔离膜， 其中，正极极片为根据本申请第二方面的正极极片。
本申请的第四方面提供一种用电设备，其包括根据本申请第三方面的电化学装置。
与现有技术相比，本申请至少具有以下有益效果：
本申请实施例提供的正极集流体包括金属导电层及设置于金属导电层的表面的过充阻断激活层，过充阻断激活层包括酯化糖类过充阻断激活材料，使采用其的电化学装置发生过充电时，能够及时切断充电电流，有效防止电化学装置发生热失控，避免引发起火、爆炸等安全问题，从而提高电化学装置的过充安全性能。本申请的用电设备包括所述的电化学装置，因而至少具有与所述电化学装置相同的优势。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本申请一个实施例中正极集流体的结构示意图。
图2是本申请另一个实施例中正极集流体的结构示意图。
图3是本申请一个实施例中正极极片的结构示意图。
图4是本申请另一个实施例中正极极片的结构示意图。
图5是本申请再一个实施例中正极极片的结构示意图。
图6是锂离子电池的一实施方式的示意图。
图7是图6的分解图。
图8是电池模块的一实施方式的示意图。
图9是电池包的一实施方式的示意图。
图10是图9的分解图。
图11是锂离子电池用作电源的用电设备的一实施方式的示意图。
图12为实施例1的锂离子二次电池的电压-温度-时间曲线图。
图13为对比例1的锂离子二次电池的电压-温度-时间曲线图。
具体实施方式
为了使本申请的发明目的、技术方案和有益技术效果更加清晰，以下结合实施例对本申请进行进一步详细说明。应当理解的是，本说明书中描述的实施例仅仅是为了解释本申请，并非为了限定本申请。
为了简便，本文仅明确地公开了一些数值范围。然而，任意下限可以与任何上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，尽管未明确记载，但是范围端点间的每个点或单个数值都包含在该范围内。因而，每个点或单个数值可以作为自身的下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本文的描述中，需要说明的是，除非另有说明，“以上”、“以下”为包含本数，“一种或多种”中“多种”的含义是两种或两种以上。
本申请的上述发明内容并不意欲描述本申请中的每个公开的实施方式或每种实现方式。如下描述更具体地举例说明示例性实施方式。在整篇申请中的多处，通过一系列实施例提供了指导，这些实施例可以以各种组合形式使用。在各个实例中，列举仅作为代表性组，不应解释为穷举。
正极集流体
本申请实施例提供了一种能改善电化学装置过充安全性能的正极集流体。
图1和图2分别提供作为示例的正极集流体10。参照图1和图2，正极集流体10包括金属导电层101及设置于金属导电层101表面的过充阻断激活层102。作为示例，过充阻断激活层102可以是设置于金属导电层101自身厚度方向相对的两个表面中的任意一者上(如图1)，也可以是设置于金属导电层101相对的两个表面上(如图2)。
过充阻断激活层102包括过充阻断激活材料、粘结材料和导电材料，其中过充阻断激活材料包括酯化糖。
本申请实施例的正极集流体10中，在金属导电层101的表面设有过充阻断激活层102，过充阻断激活层102包含酯化糖类过充阻断激活材料、粘结材料和导电材料。在电化学装置正常工作环境下，酯化糖类过充阻断激活材料的物理、化学性质稳定，并且导电材料形成连续的导电网络，使得过充阻断激活层102具有较小的电阻，保证正极集流体10具有良好的导电性能。在电化学装置发生过充电时，酯化糖类过充阻断激活材料在高温(≥60℃)和高电压(≥4.8V，相对于锂金属电位)条件下能够发生化学反 应，进而引起材料的物理结构变化，这会导致过充阻断激活层102中的导电材料颗粒相分离，造成导电网络发生断裂破坏，使过充阻断激活层102的电阻急剧增大，从而及时切断充电电流，有效防止电化学装置发生热失控，避免引发起火、爆炸等安全问题，提高电化学装置的过充安全性能。
过充阻断激活层102并不是通过过充阻断激活材料在高温时发生结晶度变化引起体积膨胀，来达到断开导电网络、切断充电电流的目的。过充阻断激活层102具有较高的可靠性，只要过充阻断激活层102的温度和电压达到上述阈值(即温度≥60℃；电压≥4.8V，相对于锂金属电位)，就能快速发生化学反应，使导电网络发生断裂破坏，及时切断充电电流。而对于依赖结晶度变化引起体积膨胀的材料，其在高温条件下仅发生物理变化，这种变化受材料涂层制备工艺及电化学装置制备工艺的影响较大，比如，材料涂层制备工艺中的温度及涂布速度、电化学装置中的电解液等，都会对材料的结晶度产生影响、且影响不可控，在电化学装置发生过充电时，材料很可能未被激发，不能及时切断充电电流，存在安全隐患。
优选地，酯化糖的糖环上具有酯基，即糖的糖环上的一个以上仲羟基被酯化。经发明人的锐意研究发现，相较于糖环的侧链上具有酯基，在糖环上具有酯基的酯化糖对高温(≥60℃)和高电压(≥4.8V，相对于锂金属电位)具有较高的响应灵敏度，使得电化学装置发生过充电时，过充阻断激活层102能够快速响应，切断充电电流，更好地提高电化学装置的过充安全性能。
本申请实施例的正极集流体10中，酯化糖可以为单酯化糖及多酯化糖中的一种或多种。单酯化糖，即糖的单酯化产物，指的是糖的一个羟基的氢原子被酰基取代的产物，优选包括糖的糖环上的一个仲羟基被酰基取代的产物。多酯化糖，即糖的多酯化产物，指的是糖的两个以上羟基的氢原子被酰基取代的产物，优选该产物的糖环上具有酯基。
在一些优选的实施例中，酯化糖包括两个以上的羟基被酯化并且保留预设量羟基的糖酯化产物。酯化糖中残留的羟基在高温高电压下，能够对酯化糖类过充阻断激活材料的激活起到促进作用，及时阻断过充电流，提高过充安全性能及可靠性。进一步地，前述预设量羟基包括位于糖环上的羟基。
糖在单酯化或多酯化后形成酯化糖的糖基团部分。糖可以是单糖、低聚糖、多聚糖、氨基糖、糖醇、去氧糖及糖醛酸中的一种或多种，例如是单糖、低聚糖及多聚糖 中的一种或多种，再例如是低聚糖及多聚糖中的一种或多种。
单糖例如包括核糖、木糖、半乳糖、甘露糖、葡萄糖及果糖中的一种或多种。
低聚糖含有2～10个单糖单元，例如包括麦芽糖、乳糖、蔗糖、聚合度为2～10的低聚纤维糖、麦芽三糖、麦芽四糖、麦芽五糖、麦芽六糖、异麦芽糖、异麦芽三糖、潘糖、甘露三糖及含有小于等于10个单糖单元的环糊精中的一种或多种。含有小于等于10个单糖单元的环糊精例如是α-环糊精、β-环糊精及γ-环糊精中的一种或多种。
多聚糖含有大于10个单糖单元，优选为含有大于10且小于等于500个单糖单元。多聚糖例如包括淀粉、纤维素、壳聚糖及含有大于10个单糖单元的环糊精中的一种或多种。
氨基糖例如是上述单糖、低聚糖、多聚糖上的部分羟基被氨基取代而得到的糖，前述部分的数量为大于等于1。
糖醇例如是山梨糖醇、甘露糖醇、麦芽糖醇、乳糖醇、木糖醇等。
去氧糖例如是上述单糖、低聚糖、多聚糖上的部分羟基被氢原子取代而得到的糖，前述部分的数量为大于等于1。
糖醛酸例如是上述单糖、低聚糖、多聚糖上的伯羟基被氧化为羧基而得到的糖。
在一些优选的实施例中，糖选自葡萄糖、低聚纤维糖、环糊精、纤维素及壳聚糖中的一种或多种。更优选地，糖选自葡萄糖、聚合度为2～10的低聚纤维糖、含有6～10个单糖单元的环糊精、聚合度为10～500的纤维素及聚合度为10～500的壳聚糖中的一种或多种。
在一些实施例中，所述酰基优选包括式1至式6所示的酰基中的一种或多种：
Figure PCTCN2020086974-appb-000001
其中，R 1、R 2、R 3、R 4、R 5、R 6、R 7各自独立地为氢原子、不饱和脂肪族基、饱和脂肪族基或芳香族基，R 8为-(CH 2) n-，0≤n≤8。
不饱和脂肪族基包括链状不饱和脂肪族基、环状脂肪族基，例如为碳原子数为2～12的链状或环状烯烃基、碳原子数为2～12的链状或环状炔烃基。再例如为选自乙烯基、1-丙烯基、2-甲基丙烯基、1-丁烯基、2-丁烯基、3-丁烯基、1-丙炔基、2-丙炔基、环丁烯基、环戊烯基、环己烯基。
饱和脂肪族基包括链状饱和脂肪族酰基、环状饱和脂肪族酰基，其中链状饱和脂肪族酰基例如是碳原子数为1～12的直链或支链烷基，如选自甲基、乙基、丙基、异丙基、丁基、异丁基、戊基、异戊基、己基及其同分异构体等，环状饱和脂肪族酰基例如是碳原子数为3～15的带侧链或不带侧链的环状烷基，如选自环丙基、环丁基、环戊基、环己基等。
芳香族基例如选自1-苯甲基、1-苯乙基等。
在式6中，n例如为1、2、3、4、5、6。
在一些优选的实施例中，酰基选自式1、式2及式5中的一种或多种。酰基更优选为式2，即优选碳酸酯类酯化糖。进一步地，R 1选自甲基、乙基、丙基、异丙基，R 2、R 5、R 6各自独立地为氢原子、甲基、乙基、丙基、异丙基。具有该些酰基的酯化糖具有更好的在高温(≥60℃)和高电压(≥4.8V，相对于锂金属电位)条件下的反应活性，在电化学装置发生过充电时具有更高的响应灵敏度，使得过充阻断激活层102快速响应，切断充电电流，进一步提高电化学装置的过充安全性能。
酰基的供体可以是相应的羧酸、含氧无机酸、酰卤、酸酐、碳酸酯、磺酸酯或磷酸酯。酰卤例如是酰氯。其中可通过控制糖类反应底物和酰基供体的摩尔比，来大体保证酯化糖的糖环上保留有预设量的羟基。
在一些优选的实施例中，过充阻断激活材料可包括单糖的多酯化产物、低聚糖的多酯化产物及多聚糖的多酯化产物中的一种或多种。进一步地，过充阻断激活材料可包括低聚糖的多酯化产物及多聚糖的多酯化产物中的一种或多种。更进一步地，多酯化产物优选碳酸酯类。更进一步地，多酯化产物中含有预设量的糖环羟基。
作为示例，过充阻断激活材料可选自葡萄糖五乙酸酯、葡萄糖-1,6-二磷酸乙酯、葡萄糖-1,6-二碳酸甲酯、β-环糊精乙酸酯、β-环糊精碳酸酯、β-环糊精磷酸酯、纤维素碳酸甲酯、纤维素碳酸乙酯、纤维素磷酸甲酯、纤维素磷酸乙酯、壳聚糖碳酸甲酯、壳聚糖碳酸乙酯、壳聚糖磷酸甲酯及壳聚糖磷酸乙酯中的一种或多种。
过充阻断激活层102的粘结材料可以采用具有良好的耐高温性能的粘结材料。粘结 材料优选包括聚偏氟乙烯(PVDF)、偏氟乙烯-六氟丙烯共聚物(PVDF-HFP)、聚胺酯、聚丙烯腈(PAN)、聚酰亚胺(PI)、环氧树脂、有机硅树脂、乙烯-醋酸乙烯共聚物(EVA)、丁苯橡胶(SBR)、苯丙橡胶、聚丙烯酸(PAA)、丙烯酸-丙烯酸酯共聚物及乙烯-丙烯酸酯共聚物(EMA)中的一种或多种。该粘结材料具有较高的热稳定性，有利于提高过充阻断激活层102在电化学装置正常工作中的稳定性；并且能够保证过充阻断激活层102与金属导电层101之间具有较高的结合力。
过充阻断激活层102的导电材料可以包括金属导电材料、碳基导电材料及导电高分子材料中的一种或多种。
金属导电材料例如包括铝、铝合金、铜、铜合金、镍、镍合金、钛及银中的一种或多种。
碳基导电材料例如包括科琴黑、中间相碳微球、活性炭、石墨、导电炭黑、乙炔黑、碳纤维、碳纳米管及石墨烯中的一种或多种。
导电高分子材料例如包括聚氮化硫类、脂肪族共轭聚合物、芳环共轭聚合物及芳杂环共轭聚合物中的一种或多种。脂肪族共轭聚合物例如是聚乙炔，芳环共轭聚合物例如是聚苯、聚萘，芳杂环共轭聚合物例如是聚吡咯、聚乙炔、聚苯胺、聚噻吩及聚吡啶中的一种或多种。还可以通过掺杂改性以提高导电高分子材料的电导率。
在一些优选的实施例中，过充阻断激活层102中，过充阻断激活材料的质量百分含量为25％～45％，粘结材料的质量百分含量为35％～60％，导电材料的质量百分含量为6％～20％。该过充阻断激活层102的电阻较小，且能够有效地改善电化学装置的过充安全性能。
更优选地，过充阻断激活层102中，过充阻断激活材料的质量百分含量为30％～40％，粘结材料的质量百分含量为45％～55％，导电材料的质量百分含量为6％～10％。
在一些优选的实施例中，过充阻断激活层102还可以包括辅助材料，辅助材料采用对过充阻断激活材料、粘结材料和导电材料均具有良好亲和性的材料。辅助材料可以改善过充阻断激活材料、粘结材料和导电材料彼此之间的相容性和亲和性，从而提高过充阻断激活材料和导电材料在粘结材料中的分散均匀性，提高过充阻断激活层102的平整性，减少层中的凹坑等缺陷，这能够提高过充阻断激活层102的整体保护作用。电化学装置过充电时，正极集流体10任意一点处都有使过充阻断激活材料作出响应，防止因为正极活性物质层20(如图3至图5)和金属导电层101之间漏电带来的安全隐 患。并且，过充阻断激活材料和导电材料均匀分散于粘结材料中，使导电材料形成均匀且连续的导电网络，保证在正常的充放电过程中，过充阻断激活层102的电阻较小，电化学装置的性能(如循环性能)较好。
辅助材料优选包括羧甲基纤维素钠(CMC-Na)、硅烷偶联剂(如乙烯基三甲氧基硅烷等)、钛酸酯偶联剂、有机聚硅氧烷、高碳醇脂肪酸酯复合物、聚氧乙烯聚氧丙烯季戊四醇醚、聚氧乙烯聚氧丙醇胺醚、聚氧丙烯甘油醚及聚氧丙烯聚氧乙烯甘油醚中的一种或多种。钛酸酯偶联剂例如是双(二辛氧基焦磷酸酯基)乙撑钛酸酯。有机聚硅氧烷例如是乳化硅油，再例如是聚二甲基硅氧烷。在一些实施例中，辅助材料包括乙烯基三甲氧基硅烷和/或聚氧丙烯甘油醚。
过充阻断激活层102中辅助材料的质量百分含量优选为1％～10％，更优选为2％～8％，如5％。
在一些实施例中，过充阻断激活层102中包括3％的乙烯基三甲氧基硅烷和2％的聚氧丙烯甘油醚。
在一些实施例中，过充阻断激活层102可以仅设置于金属导电层101的单面表面。在这些实施例中，过充阻断激活层102的厚度优选为0.3μm～10μm，即d＝0.3μm～10μm。过充阻断激活层102的厚度在上述范围内，使正极集流体10具有较小的内阻，并能有效发挥过充阻断激活层102对电化学装置过充安全性能的改善作用。此外，过充阻断激活层102的厚度在上述范围内，还有利于保证电化学装置具有较低的体积及重量，使其具有较高的体积能量密度和重量能量密度。进一步地，d可以为2μm～7μm。更进一步地，d可以为3μm～5μm。
在一些实施例中，过充阻断激活层102可以设置于金属导电层101自身厚度方向相对的两个表面，金属导电层101的两个表面上过充阻断激活层102的总厚度为0.5μm～18μm，每个表面上过充阻断激活层102的厚度大于或等于0.25μm，即d 1+d 2＝0.5μm～18μm，d 1≥0.25μm，d 2≥0.25μm。过充阻断激活层102的厚度在上述范围内，使正极集流体10具有较小的内阻，并能有效发挥过充阻断激活层102对电化学装置过充安全性能的改善作用。此外，过充阻断激活层102的厚度在上述范围内，还有利于保证电化学装置具有较低的体积及重量，使其具有较高的体积能量密度和重量能量密度。
在一些可选的实施例中，0.25μm≤d 1≤10μm；0.25μm≤d 2≤10μm。优选地，2μm≤d 1≤7μm；2μm≤d 2≤7μm。
在一些优选的实施例中，在所有需要设置正极活性物质层20的金属导电层101的表面均设置含有过充阻断激活材料的过充阻断激活层102。这样可以在进一步提高电化学装置过充安全性能的情况下，实现较高的电流阻断效果的重复性和可靠性。
在本申请的实施例中，对金属导电层101的厚度D没有特别的限制，可以根据实际需求进行选择。例如D＝1μm～20μm，如D＝8μm～15μm。
本申请的正极集流体10中，金属导电层101可以是具有良好导电性能及机械性能的金属箔或金属板。金属导电层101可包括铝、铝合金、镍、镍合金、钛、钛合金、银及银合金中的一种或多种，优选包括铝及铝合金中的一种或多种。铝合金中铝元素的重量百分含量优选为80％～100％，更优选为90％以上。铝合金例如为铝锆合金。
在一些优选的实施例中，金属导电层101可以是铝箔。
接下来，本申请实施例提供一种正极集流体10的制备方法，通过该制备方法能够制备得到上述任意一种正极集流体10。方法包括过充阻断激活层浆料的制作步骤S100和集流体的制作步骤S200。
S100、按预设重量比将过充阻断激活材料、粘结材料和导电材料分散于溶剂中，形成均匀的过充阻断激活层浆料。
在过充阻断激活层浆料的制作步骤S100，过充阻断激活材料、粘结材料和导电材料可以为上述的材料，在此不再赘述。溶剂例如是N-甲基吡咯烷酮(NMP)。
在过充阻断激活层浆料中，还可以加入上述的辅助材料。辅助材料可以改善过充阻断激活材料、粘结材料和导电材料彼此之间的相容性，并起到消泡作用，从而提高过充阻断激活材料和导电材料在粘结材料中的分散均匀性，形成更加稳定的浆料。辅助材料还可以促进浆料在金属导电层表面充分铺展，提高过充阻断激活层的平整性，减少层中的凹坑等缺陷。过充阻断激活层的整体保护作用得到提高，使电化学装置过充电时，正极集流体任意一点处都有使过充阻断激活材料作出响应，防止漏电带来的安全隐患。并且，过充阻断激活材料和导电材料均匀分散于粘结材料中，使导电材料形成均匀且连续的导电网络，保证在正常的充放电过程中，过充阻断激活层具有较小的电阻，电化学装置的性能较好。
可以采用搅拌机进行物料的混合，通过搅拌使物料混合均匀，形成均匀的浆料。搅拌机可以是公知的用于物料混合的搅拌机，如行星搅拌机。
可以进一步采用真空除气法消除浆料中的气泡，进一步提高过充阻断激活层的平 整性，减少层中的凹坑等缺陷。
S200、将过充阻断激活层浆料涂覆于金属导电层的表面，经干燥后形成过充阻断激活层，得到正极集流体。
在步骤S200，可采用本领域已知的涂覆方法使过充阻断激活层浆料充分地涂覆于金属导电层的表面。例如采用凹版或微凹版涂布机，能够使涂层具有较高的均匀性。
在步骤S200，干燥可以是自然晾干、红外干燥、或者是在40℃～120℃的条件下进行鼓风加热干燥。例如在60℃～80℃的热风条件下干燥。
正极极片
本申请实施例还提供一种正极极片。正极极片包括根据本申请实施例的正极集流体10及设置于正极集流体10上的正极活性物质层20。本申请实施例的正极极片由于采用了本申请实施例的正极集流体10，因此也具有相应的优势。
本申请实施例的正极极片中，包括正极集流体10以及设置于正极集流体10至少一个表面上的正极活性物质层20。
在一些实施例中，参照图3和图4，正极集流体10在自身厚度方向包括相对的两个表面，正极活性物质层20设置于这两个表面侧，其中，在至少一侧的正极活性物质层20与金属导电层101之间设置有过充阻断激活层102。其中优选地，如图3，在两侧的正极活性物质层20与金属导电层101之间均设置有过充阻断激活层102。
当然，在其他的实施例中，参照图5，可以是正极集流体10的金属导电层101在自身厚度方向包括相对的两个表面，过充阻断激活层102设置于两个表面中的任意一者上，正极活性物质层20设置于过充阻断激活层102的背向金属导电层101的表面。
在一些实施例中，过充阻断激活层102的面积为S 1，设置于过充阻断激活层102背向金属导电层101的表面的正极活性物质层102的面积为S 2，面积之比优选为0.8≤S 1/S 2≤1，更优选为0.98≤S 1/S 2≤1，更优选为0.99≤S 1/S 2≤1。过充阻断激活层102对正极活性物质层102的覆盖面积越大，越能够提高电化学装置的过充安全性能。
正极活性物质层20包括正极活性物质，其可以是本领域已知的能够进行活性离子可逆脱嵌的正极活性物质，本申请不做限制。
例如用于锂离子二次电池的正极活性物质，可以包括锂过渡金属复合氧化物、锂过渡金属复合氧化物添加其它过渡金属或非过渡金属或非金属得到的复合氧化物中的一种或多种。其中过渡金属可以是Mn、Fe、Ni、Co、Cr、Ti、Zn、V、Al、Zr、Ce及 Mg中的一种或多种。
作为示例，正极活性物质可选自锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物、橄榄石结构的含锂磷酸盐中的一种或多种；如LiMn 2O 4、LiNiO 2、LiCoO 2、LiNi 1-yCo yO 2(0<y<1)、LiNi aCo bAl 1-a-bO 2(0<a<1，0<b<1，0<a+b<1)、LiMn 1-m-nNi mCo nO 2(0<m<1，0<n<1，0<m+n<1)、LiMPO 4(M可以为Fe、Mn、Co中的一种或多种)及Li 3V 2(PO 4) 3中的一种或多种。LiMn 1-m-nNi mCo nO 2例如是LiMn 0.1Ni 0.8Co 0.1O 2、LiMn 0.3Ni 0.5Co 0.2O 2、LiMn 0.2Ni 0.6Co 0.2O 2、LiMn 1/3Ni 1/3Co 1/3O 2等。
可选地，正极活性物质层20还包括粘结剂，本申请实施例对粘结剂的种类不做限制。作为示例，粘结剂可以为丁苯橡胶(SBR)、水性丙烯酸树脂(water-based acrylic resin)、羧甲基纤维素钠(CMC-Na)、聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或多种。
可选地，正极活性物质层20还包括导电剂，本申请实施例对导电剂的种类不做限制。作为示例，导电剂可以为石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或多种。
正极极片可按照本领域常规方法制备。作为示例，将正极活性物质、导电剂和粘结剂分散于溶剂中，形成均匀的正极浆料，溶剂例如是N-甲基吡咯烷酮(NMP)；将正极浆料涂覆在正极集流体10上，经烘干、冷压等工序后，得到正极极片。
电化学装置
本申请实施例还提供一种电化学装置，电化学装置包括正极极片、隔离膜及负极极片，其中正极极片采用本申请实施例的正极极片。
本申请实施例的电化学装置由于采用了本申请实施例的正极极片，因而也具有相应的优势，如较高的过充电安全性能，更优选地包括上述的其他有益效果。
电化学装置可以是裸电芯，也可以是包含裸电芯和电解质的电池。电池例如是二次电池(如锂离子二次电池、钠离子电池、镁离子电池等)、一次电池(如锂一次电池等)等，但并不限于此。
裸电芯可以是将正极极片、隔离膜、负极极片按顺序堆叠形成的层叠结构体，也可以是将正极极片、隔离膜、负极极片按顺序堆叠后经卷绕得到的卷绕结构体。其 中，隔离膜处于正极极片与负极极片之间起到隔离的作用。
裸电芯中，负极极片可以包括负极集流体及设置于负极集流体至少一个表面的负极活性物质层。例如，负极活性物质层设置于负极集流体在自身厚度方向相对的两个表面中的任意一者或两者上。
负极活性物质层可以采用本领域已知的能够进行活性离子可逆脱嵌的负极活性物质，本申请不做限制。
例如用于锂离子二次电池的负极活性物质可包括金属锂、天然石墨、人造石墨、中间相微碳球(简写为MCMB)、硬碳、软碳、硅、硅-碳复合物、SiO x(0<x<2)、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO 2、尖晶石结构的钛酸锂及Li-Al合金中的一种或多种。
可选地，负极活性物质层还包括粘结剂，本申请实施例对粘结剂的种类不做限制。作为示例，粘结剂可以为丁苯橡胶(SBR)、水性丙烯酸树脂(water-based acrylic resin)、羧甲基纤维素钠(CMC-Na)、聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)中的一种或多种。
可选地，负极活性物质层还包括导电剂，本申请实施例对导电剂的种类不做限制。作为示例，导电剂可以为石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或多种。
负极极片可以按照本领域常规方法制备。作为示例，可以将负极活性物质、导电剂和粘结剂分散于溶剂中，形成均匀的负极浆料，溶剂例如是去离子水；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，得到负极极片。
本申请实施例对隔离膜的种类不做具体的限制，可以是能够被用于电化学装置的任意多孔隔离膜，例如玻璃纤维隔离膜、无纺布隔离膜、聚乙烯隔离膜、聚丙烯隔离膜、聚偏二氟乙烯隔离膜以及它们中的一种或多种形成的多层复合膜，但不限于此。
电池中，电解质可以采用固体电解质，也可以非水电解液。对它们的种类均不做具体的限制，可根据需求进行选择。
作为示例，非水电解液包括有机溶剂和电解质盐。
例如用于锂离子二次电池的有机溶剂可以选自碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二 丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)、二乙砜(ESE)中的一种或多种，但并不限于此。
例如用于锂离子二次电池的电解质盐可以选自LiPF 6(六氟磷酸锂)、LiBF 4(四氟硼酸锂)、LiClO 4(高氯酸锂)、LiAsF 6(六氟砷酸锂)、LiFSI(双氟磺酰亚胺锂)、LiTFSI(双三氟甲磺酰亚胺锂)、LiTFS(三氟甲磺酸锂)、LiDFOB(二氟草酸硼酸锂)、LiBOB(二草酸硼酸锂)、LiPO 2F 2(二氟磷酸锂)、LiDFOP(二氟二草酸磷酸锂)及LiTFOP(四氟草酸磷酸锂)中的一种或多种，但并不限于此。
非水电解液中还可选地包括改善电池性能的添加剂，对添加剂的种类没有具体的限制，可根据需求进行选择。
电芯可以按照本领域已知的方法制备。例如，将正极极片、隔离膜及负极极片按顺序层叠好，使隔离膜处于正极极片与负极极片之间起到隔离的作用，得到电芯，也可以是经卷绕后得到电芯。
电池可以按照本领域已知的方法制备。例如，将电芯置于外包装中，注入非水电解液并封口，得到电池。
本申请对电化学装置的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。在一些实施例中，如图6所示，电化学装置是方形结构的二次电池5。
在一些实施例中，二次电池5可包括外包装，用于封装电芯和电解液。
在一些实施例中，二次电池5的外包装可以是硬壳，如硬塑料壳、铝壳、钢壳等。二次电池5的外包装也可以是软包，如袋式软包。软包的材质可以是塑料，如可包括聚丙烯PP、聚对苯二甲酸丁二醇酯PBT、聚丁二酸丁二醇酯PBS等中的一种或几种。
在一些实施例中，参照图7，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经叠片工艺或卷绕工艺形成电芯52。电芯52封装于所述容纳腔。电解液浸润于电芯52中。
二次电池5所含电芯52的数量可以为一个或几个，可根据需求来调节。
在一些实施例中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为多个，具体数量可根据电池模块的应用和容量来调节。
图8作为一个示例的电池模块4。参照图8，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施例中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以根据电池包的应用和容量进行调节。
图9和图10作为一个示例的电池包1。参照图9和图10，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
用电设备
本申请的实施例还提供一种用电设备，所述用电设备包括本申请所述的电化学装置。所述电化学装置可用作所述用电设备的电源，也可以作为所述用电设备的能量存储单元。所述用电设备可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。所述用电设备可以根据其使用需求来选择电化学装置，如一次电池、二次电池、电池模块或电池包。
图11是作为一个示例的用电设备。该用电设备为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电设备对电化学装置的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的用电设备可以是手机、平板电脑、笔记本电脑等。该用电设备通常要求轻薄化，可以采用二次电池作为电源。
实施例
下述实施例更具体地描述了本申请公开的内容，这些实施例仅仅用于阐述性说明，因为在本申请公开内容的范围内进行各种修改和变化对本领域技术人员来说是明 显的。除非另有声明，以下实施例中所报道的所有份、百分比、和比值都是基于重量计，而且实施例中使用的所有试剂都可商购获得或是按照常规方法进行合成获得，并且可直接使用而无需进一步处理，以及实施例中使用的仪器均可商购获得。
实施例1
正极集流体的制备
制作过充阻断激活层的浆料：取53重量份聚偏氟乙烯(PVDF)、7份导电炭黑(Super-P)、38重量份葡萄糖五乙酸酯、及2重量份聚氧丙烯甘油醚置于行星式搅拌釜内，再加入900重量份N-甲基吡咯烷酮(NMP)作为分散溶剂，快速搅拌5小时形成均匀稳定的浆料。
制作正极集流体：将上述均匀稳定的浆料抽真空除气泡，再用凹版或微凹版涂布机在金属导电层铝箔表面进行双面涂布，烘干后得到均匀、致密的过充阻断激活层，制得正极集流体，其中金属导电层铝箔的厚度为12μm，单面过充阻断激活层的厚度均为3μm。
正极极片的制备
将正极活性物质LiNi 0.8Co 0.1Mn 0.1O 2、导电剂Super-P、粘结剂PVDF按照重量比95:2:3分散于溶剂NMP中，充分搅拌混合均匀得到正极浆料；将正极浆料涂覆于正极集流体的相对两个表面，经烘干、冷压后，得到正极极片，其中，在金属导电层单面侧，过充阻断激活层的面积S 1与正极活性物质层的面积S 2之比S 1/S 2为1，过充阻断激活层对正极活性物质层的覆盖率为100％。
负极极片的制备
将负极活性物质人造石墨、导电剂Super-P、粘结剂丁苯橡胶(SBR)及羧甲基纤维素钠(CMC-Na)按照重量比93:3:2:2分散于溶剂去离子水中，搅拌混合均匀后得到负极浆料。之后将负极浆料涂覆在负极集流体铜箔的相对两个表面，经烘干、冷压后，得到负极极片。
电解液的制备
将碳酸亚乙酯(EC)、碳酸亚丙酯(PC)及碳酸二甲酯(DMC)按照重量比为1:1:1混合均匀，得到有机溶剂；再将锂盐LiPF 6溶解于上述有机溶剂中，混合均匀，得到电解液，其中LiPF 6的浓度为1mol/L。
锂离子二次电池的制备
将正极极片、聚乙烯多孔隔离膜、负极极片按顺序层叠好，然后卷绕得到电芯；将电芯装入外包装中，注入电解液并封装，得到锂离子二次电池。
实施例2
与实施例1不同的是，过充阻断激活材料为34重量份葡萄糖-1,6-二磷酸乙酯，粘结材料为53重量份PVDF，导电材料为7重量份导电炭黑(Super-P)和1重量份碳纳米管(CNT)，辅助材料为3重量份乙烯基三甲氧基硅烷和2重量份聚氧丙烯甘油醚。
实施例3
与实施例1不同的是，过充阻断激活材料为37重量份葡萄糖-1,6-二磷酸甲酯，粘结材料为52重量份PVDF，导电材料为5重量份Super-P和1重量份CNT，辅助材料为3重量份乙烯基三甲氧基硅烷和2重量份聚氧丙烯甘油醚。
实施例4
与实施例1不同的是，过充阻断激活材料为36重量份β-环糊精乙酸酯，粘结材料为52重量份PVDF，导电材料为7重量份Super-P，辅助材料为3重量份乙烯基三甲氧基硅烷和2重量份聚氧丙烯甘油醚。
实施例5
与实施例4不同的是，单面过充阻断激活层的厚度均为2μm。
实施例6
与实施例1不同的是，过充阻断激活材料为36重量份β-环糊精碳酸酯，粘结材料为52重量份PVDF，导电材料为7重量份Super-P，辅助材料为3重量份乙烯基三甲氧基硅烷和2重量份聚氧丙烯甘油醚。
实施例7
与实施例6不同的是，单面过充阻断激活层的厚度均为5μm。
实施例8
与实施例1不同的是，过充阻断激活材料为36重量份β-环糊精磷酸酯，粘结材料为52重量份PVDF，导电材料为7重量份Super-P，辅助材料为3重量份乙烯基三甲氧基硅烷和2重量份聚氧丙烯甘油醚。
实施例9
与实施例8不同的是，单面过充阻断激活层的厚度均为7μm。
实施例10
与实施例1不同的是，过充阻断激活材料为35重量份纤维素碳酸甲酯，粘结材料为50重量份SBR，导电材料为10重量份Super-P，辅助材料为5重量份CMC-Na，分散溶剂为去离子水。
实施例11
与实施例1不同的是，过充阻断激活材料为35重量份壳聚糖碳酸甲酯，粘结材料为50重量份PVDF，导电材料为10重量份Super-P，辅助材料为3重量份乙烯基三甲氧基硅烷和2重量份聚氧丙烯甘油醚。
实施例12
与实施例1不同的是，过充阻断激活材料为40重量份纤维素碳酸甲酯，粘结材料为50重量份PVDF，导电材料为8重量份Super-P和2重量份CNT，未添加辅助材料。
实施例13
与实施例1不同的是，过充阻断激活材料为35重量份纤维素碳酸甲酯，粘结材料为53重量份PAA，导电材料为7重量份Super-P，辅助材料为3重量份乙烯基三甲氧基硅烷和2重量份聚氧丙烯甘油醚，分散溶剂为去离子水；以及在金属导电层单面侧，过充阻断激活层的面积S 1与正极活性物质层的面积S 2之比S 1/S 2为98％。
实施例14
与实施例1不同的是，过充阻断激活材料为35重量份纤维素碳酸甲酯，粘结材料为53重量份PVDF，导电材料为5重量份Super-P和2重量份CNT，辅助材料为3重量份乙烯基三甲氧基硅烷和2重量份聚氧丙烯甘油醚；以及单面过充阻断激活层的厚度均为0.5μm。
实施例15
与实施例1不同的是，过充阻断激活材料为35重量份纤维素碳酸甲酯，粘结材料为53重量份PVDF，导电材料为7重量份Super-P，辅助材料为3重量份乙烯基三甲氧基硅烷和2重量份聚氧丙烯甘油醚。
实施例16
与实施例5不同的是，过充阻断激活层的浆料在金属导电层铝箔表面进行单面涂布，烘干后得到均匀、致密的过充阻断激活层，制得正极集流体，其中金属导电层铝箔的厚度为12μm，过充阻断激活层的厚度为10μm。
实施例17
与实施例1不同的是，过充阻断激活材料为35重量份纤维素碳酸甲酯，粘结材料为53重量份PVDF，导电材料为5重量份Super-P和2重量份CNT，辅助材料为3重量份乙烯基三甲氧基硅烷和2重量份聚氧丙烯甘油醚；以及正极活性物质为LiCoO 2。
对比例1
与实施例1不同的是，正极集流体为12μm厚的铝箔，未设置过充阻断激活层。
对比例2
与实施例1不同的是，正极集流体包括12μm厚的铝箔导电层及设置于铝箔导电层的相对两个表面的涂层；制作涂层的浆料包括：取5重量份CMC-Na、85重量份SBR、及10重量份Super-P置于行星式搅拌釜内，再加入900重量份去离子水作为分散溶剂，快速搅拌5小时形成均匀稳定的浆料。其余步骤与实施例1相同。
对比例3
与实施例1不同的是，正极集流体包括12μm厚的铝箔导电层及设置于铝箔导电层的相对两个表面的涂层；制作涂层的浆料包括：取90重量份PAA及10重量份Super-P置于行星式搅拌釜内，再加入900重量份去离子水作为分散溶剂，快速搅拌5小时形成均匀稳定的浆料。其余步骤与实施例1相同。
对比例4
与实施例1不同的是，正极集流体包括12μm厚的铝箔导电层及设置于铝箔导电层的相对两个表面的涂层；制作涂层的浆料包括：取90重量份PVDF及10重量份Super-P置于行星式搅拌釜内，再加入900重量份NMP作为分散溶剂，快速搅拌5小时形成均匀稳定的浆料。其余步骤与实施例1相同。
对比例5
与实施例17不同的是，正极集流体为12μm厚的铝箔，未设置过充阻断激活层。
对比例6
与实施例17不同的是，正极集流体包括12μm厚的铝箔导电层及设置于铝箔导电层的相对两个表面的涂层；制作涂层的浆料包括：取90重量份PVDF及10重量份Super-P置于行星式搅拌釜内，再加入900重量份NMP作为分散溶剂，快速搅拌5小时形成均匀稳定的浆料。其余步骤与实施例14相同。
测试部分
(1)锂离子二次电池的过充安全性能测试
在25±2℃下，将锂离子二次电池以1C倍率恒流充电至4.25V，之后以4.25V恒压充电至电流为0.05C，静置30min；然后用夹具将电池固定好，并放置在过充电安全测试设备上，环境温度控制在25±2℃，静置5min后，以1C倍率对满充状态的电池进行过充电，记录每个电池的实时电压和温度变化，直至电池发生起火或爆炸或充电停止。每个实施例和对比例取10个电池进行测试，电池未发生起火或爆炸则通过测试，否则不通过。
(2)锂离子二次电池的循环性能测试
在25±2℃下，将锂离子二次电池以1C恒流充电至4.25V，之后以4.25V恒压充电至电流为0.05C，静置5min，然后以1C恒流放电至2.8V，此为一个充放电循环过程，此次的放电容量为首次循环的放电容量。将锂离子二次电池按照上述方法进行100次循环充放电测试，记录每一次循环的放电容量。
循环容量保持率(％)＝第100次循环的放电容量/首次循环的放电容量×100％
实施例1～17和对比例1～6的测试结果示于下面的表1。
表1
  过充安全性能测试通过率 循环100次的容量保持率(％)
实施例1 7/10 91.3
实施例2 9/10 91.5
实施例3 10/10 91.1
实施例4 8/10 93.7
实施例5 7/10 94.0
实施例6 10/10 93.6
实施例7 10/10 92.8
实施例8 10/10 93.8
实施例9 10/10 91.9
实施例10 10/10 94.2
实施例11 10/10 94.5
实施例12 6/10 94.1
实施例13 8/10 94.6
实施例14 5/10 94.7
实施例15 10/10 94.3
实施例16 10/10 94.3
实施例17 10/10 93.9
对比例1 0/10 94.8
对比例2 0/10 94.5
对比例3 0/10 94.7
对比例4 0/10 94.4
对比例5 0/10 94.3
对比例6 0/10 95.1
图13为对比例1的锂离子二次电池的电压-温度-时间曲线图，当电池发生过充电时，电池温度急剧升高，电池发生热失控而失效，发生起火、爆炸，造成安全风险。图12为实施例1的锂离子二次电池的电压-温度-时间曲线图，当电池发生过充电时，过充阻断激活层能够快速地做出响应，切断外部充电电流，抑制电池温度升高，从而显著改善电池的过充安全性能。由图12和图13的对比分析可以看出，通过在正极集流体中设置过充阻断激活层，锂离子二次电池的过充安全性能得到显著的提升。
从表1中实施例1～16和对比例1～4以及实施例17和对比例5～6的比较可以得知，通过在正极集流体中设置过充阻断激活层，锂离子二次电池发生过充电时，过充阻断激活层能够及时切断外部充电电流，使锂离子二次电池的过充安全性能得到显著的提升，且正常情况下充放电使用的锂离子二次电池的循环性能没有受到明显影响，能够保持较高的循环容量保持率。
从实施例12和实施例13、15的结果可以看出，通过进一步添加辅助材料，过充阻断激活层能够更好地改善电池的过充安全性能。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (13)

  1. 一种正极集流体，包括：
    金属导电层；
    过充阻断激活层，设置于所述金属导电层的表面，所述过充阻断激活层包括过充阻断激活材料、粘结材料和导电材料，其中所述过充阻断激活材料包括酯化糖。
  2. 根据权利要求1所述的正极集流体，其中，所述酯化糖的糖环上具有酯基。
  3. 根据权利要求1或2所述的正极集流体，其中，所述酯化糖为糖的部分或全部羟基的氢原子被酰基取代而得到的单酯化糖及多酯化糖中的一种或多种；
    所述糖优选包括单糖、低聚糖、多聚糖、氨基糖、糖醇、去氧糖及糖醛酸中的一种或多种，更优选包括葡萄糖、纤维素、壳聚糖及环糊精中的一种或多种；
    所述酰基优选包括式1至式6所示的酰基中的一种或多种：
    Figure PCTCN2020086974-appb-100001
    其中，R 1、R 2、R 3、R 4、R 5、R 6、R 7各自独立地为氢原子、不饱和脂肪族基、饱和脂肪族基或芳香族基，R 8为-(CH 2) n-，0≤n≤8。
  4. 根据权利要求1至3任一项所述的正极集流体，其中，所述酯化糖包括葡萄糖五乙酸酯、葡萄糖-1,6-二磷酸乙酯、葡萄糖-1,6-二碳酸甲酯、β-环糊精乙酸酯、β-环糊精碳酸酯、β-环糊精磷酸酯、纤维素碳酸甲酯、纤维素碳酸乙酯、纤维素磷酸甲酯、纤维素磷酸乙酯、壳聚糖碳酸甲酯、壳聚糖碳酸乙酯、壳聚糖磷酸甲酯及壳聚糖磷酸乙酯中的一种或多种。
  5. 根据权利要求1至4任一项所述的正极集流体，其中，
    所述过充阻断激活层中，所述过充阻断激活材料的质量百分含量为25％～45％，所 述粘结材料的质量百分含量为35％～60％，所述导电材料的质量百分含量为6％～20％；
    优选地，所述过充阻断激活层中，所述过充阻断激活材料的质量百分含量为30％～40％，所述粘结材料的质量百分含量为45％～55％，所述导电材料的质量百分含量为6％～10％。
  6. 根据权利要求1至5任一项所述的正极集流体，其中，所述过充阻断激活层还包括辅助材料，所述辅助材料包括羧甲基纤维素钠、硅烷偶联剂、钛酸酯偶联剂、有机聚硅氧烷、高碳醇脂肪酸酯复合物、聚氧乙烯聚氧丙烯季戊四醇醚、聚氧乙烯聚氧丙醇胺醚、聚氧丙烯甘油醚及聚氧丙烯聚氧乙烯甘油醚中的一种或多种。
  7. 根据权利要求6所述的正极集流体，其中，所述过充阻断激活层中所述辅助材料的质量百分含量为1％～10％，优选为2％～8％。
  8. 根据权利要求1至7任一项所述的正极集流体，其中，
    所述过充阻断激活层设置于所述金属导电层的单面表面，所述过充阻断激活层的厚度为0.3μm～10μm；和/或，
    所述过充阻断激活层设置于所述金属导电层相对的两个表面，所述金属导电层的所述两个表面上所述过充阻断激活层的总厚度为0.5μm～18μm，每个所述表面上所述过充阻断激活层的厚度大于或等于0.25μm。
  9. 根据权利要求1至8任一项所述的正极集流体，其中，
    所述粘结材料包括聚偏氟乙烯、偏氟乙烯-六氟丙烯共聚物、聚胺酯、聚丙烯腈、聚酰亚胺、环氧树脂、有机硅树脂、乙烯-醋酸乙烯共聚物、丁苯橡胶、苯丙橡胶、聚丙烯酸、聚丙烯酸-丙烯酸酯共聚物及聚乙烯-丙烯酸酯共聚物中的一种或多种；和/或，
    所述导电材料为金属导电材料、碳基导电材料及导电高分子材料中的一种或多种，所述金属材料优选包括铝、铝合金、铜、铜合金、镍、镍合金、钛及银中的一种或多种，所述碳基导电材料优选包括科琴黑、中间相碳微球、活性炭、石墨、导电炭黑、乙炔黑、碳纤维、碳纳米管及石墨烯中的一种或多种，所述导电高分子材料优选包括聚氮化硫类、脂肪族共轭聚合物、芳环共轭聚合物及芳杂环共轭聚合物中的一种或多种。
  10. 一种正极极片，包括：
    根据权利要求1至9任一项所述的正极集流体；
    正极活性物质层，设置于所述正极集流体的所述过充阻断激活层背向所述金属导电层的表面。
  11. 根据权利要求10所述的正极极片，其中，所述金属导电层同一表面侧的所述过充阻断激活层和所述正极活性物质层的面积之比为80％～100％，优选为98％～100％。
  12. 一种电化学装置，包括正极极片、负极极片及隔离膜，其中，所述正极极片为根据权利要求10或11所述的正极极片。
  13. 一种用电设备，包括根据权利要求12所述的电化学装置。
PCT/CN2020/086974 2019-05-24 2020-04-26 正极集流体、正极极片、电化学装置和包含该电化学装置的用电设备 WO2020238521A1 (zh)

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