WO2022199301A1 - 一种锂离子电池的阳极极片及其应用 - Google Patents

一种锂离子电池的阳极极片及其应用 Download PDF

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WO2022199301A1
WO2022199301A1 PCT/CN2022/077075 CN2022077075W WO2022199301A1 WO 2022199301 A1 WO2022199301 A1 WO 2022199301A1 CN 2022077075 W CN2022077075 W CN 2022077075W WO 2022199301 A1 WO2022199301 A1 WO 2022199301A1
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lithium
anode
active material
microns
layer
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PCT/CN2022/077075
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English (en)
French (fr)
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刘智
范海林
刘斯通
史东洋
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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 EP22773963.8A priority Critical patent/EP4280297A1/en
Publication of WO2022199301A1 publication Critical patent/WO2022199301A1/zh
Priority to US18/296,794 priority patent/US20230246157A1/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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
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    • 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
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
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    • H01M10/00—Secondary cells; Manufacture thereof
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    • H01M10/052—Li-accumulators
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    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
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    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
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    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
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    • 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
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    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • H—ELECTRICITY
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    • 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 application relates to the field of batteries, and more particularly to an anode electrode sheet for lithium ion batteries, and also to a lithium ion battery, a battery module, a battery pack and an electrical device comprising the anode electrode sheet, and a lithium ion inhibitor A method for lithium deposition on the surface of an anode plate in a battery.
  • rechargeable batteries also known as secondary batteries
  • secondary batteries are increasingly used in applications such as consumer goods, new energy vehicles, large-scale energy storage, aerospace, marine, heavy duty High-tech, high-strength, high-demand fields such as machinery are even used as main power and energy supply equipment in these fields.
  • lithium ion secondary batteries have attracted much attention due to their excellent performance.
  • the lithium-ion secondary battery itself also has some major defects that have not been solved so far. For example, in the daily charging and discharging process of the lithium-ion battery, the process of intercalating lithium ions in the electrolyte into the anode is not uniform.
  • Lithium metal dendrites may be generated on the anode surface after long-term cycling. In severe cases, these dendrites may penetrate the separator, and there is a risk of safety accidents such as battery short circuit, expansion, combustion, and even explosion.
  • a ceramic insulating layer is arranged on the surface of the anode, but this approach cannot really solve the problem that lithium is deposited on the surface of the graphite layer of the anode but cannot be inserted into the bottom of the graphite layer.
  • lithium ions can be preferentially intercalated into the underlying active material instead of It preferentially accumulates in the lithium deposition inhibitory layer, effectively avoiding the phenomenon of lithium deposition on the anode surface in a very simple and economical way, and at the same time, it can reduce the anode/cathode capacity ratio (CB value, Cell Balance value) of lithium ion batteries, and greatly improve lithium ion First-time coulombic efficiency, energy density, and ideal cycle life and charge-discharge voltage platform of the battery.
  • CB value Cell Balance value
  • a first aspect of the present application provides an anode sheet for a lithium ion battery, the anode sheet comprising:
  • the lithium deposition inhibiting layer comprises at least one of the following lithium deposition inhibiting materials: LiNi 0.85 Co 0.075 Mn 0.075 O 2 , LiNi 0.8 Co 0.1 Mn 0.1 O 2 , LiNi 0.7 Co 0.15 Mn 0.15 O 2 , LiNi 0.6 Co 0.2 Mn 0.2 O 2 , LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiFeO 2 , LiFePO 4 , LiCoPO 4 , LiNiPO 4 , LiMnPO 4 , Li 4 Ti 5 O 12 .
  • the LiNi x Co y Mn z Few O 2 is a composite metal oxide of a layered structure
  • the LiMPO 4 is a compound of an olivine structure
  • the Li 4 Ti 5 O 12 is a compound of spinel structure.
  • the lithium deposition inhibiting layer comprises a first adhesive
  • the first adhesive is selected from one or more of the following: polyvinylidene fluoride, polytetrafluoroethylene , Polychlorotrifluoroethylene.
  • the lithium deposition inhibiting layer contains no conductive material.
  • the lithium deposition inhibiting layer does not contain a carbon-based conductive material. In another embodiment of the first aspect of the present application, the lithium deposition inhibiting layer does not contain any one of the following carbon-based conductive materials: graphite, mesocarbon microspheres, soft carbon, hard carbon, carbon nanotubes, carbon fibers , graphene, carbon black, Ketjen black, Super P, acetylene black, furnace black, vapor-grown carbon fiber (VGCF), these carbon-based conductive materials are not included in the lithium deposition inhibiting layer.
  • carbon-based conductive materials graphite, mesocarbon microspheres, soft carbon, hard carbon, carbon nanotubes, carbon fibers , graphene, carbon black, Ketjen black, Super P, acetylene black, furnace black, vapor-grown carbon fiber (VGCF), these carbon-based conductive materials are not included in the lithium deposition inhibiting layer.
  • the thickness of the lithium evolution inhibiting layer is 1.8-20 micrometers; the thickness of the anode active material layer is 30-340 micrometers, and the thickness of the lithium evolution inhibiting layer is 30-340 micrometers. It is 0.018 times to 0.2 times the thickness of the anode active material layer.
  • the lithium evolution inhibiting layer has a thickness of 2.3-15 microns; the anode active material layer has a thickness of 55-260 microns, and the lithium evolution inhibiting layer has a thickness of 55-260 microns. It is 0.023 times to 0.11 times the thickness of the anode active material layer.
  • the anode active material layer comprises: an active material selected from one or more of the following: graphite, hard carbon, silicon-based material, tin-based material;
  • Two adhesives which are selected from one or more of the following: styrene-butadiene rubber, water-soluble unsaturated resin SR-1B, sodium alginate, polyurethane, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polycarboxymethyl fiber Sodium, acrylamide, polyvinyl alcohol, and carboxymethyl chitosan;
  • Conductive agents carbon nanotubes, carbon fibers, graphene, carbon black, Ketjen black, Super P.
  • the potential difference between the lithium evolution inhibiting layer and the anode active material layer is 1-4 volts.
  • the current collector is a metal foil, a metal alloy foil, a polymer sheet with a metal coating, or a polymer sheet with a metal alloy coating; wherein the The metal in the metal foil and metal coating is selected from copper, silver, iron, titanium, and nickel; the metal alloy in the metal alloy foil and metal alloy coating is selected from copper alloy, nickel alloy, titanium alloy, silver alloy, iron alloy ;
  • the polymer sheet is selected from polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene and mixtures and copolymers thereof.
  • a second aspect of the present application provides a lithium-ion battery including a cathode electrode sheet, an electrolyte, and the anode electrode sheet of the present application.
  • the capacity ratio of the anode electrode sheet and the cathode electrode sheet is 1.07 to 1.01, for example, 1.07 to 1.03.
  • a third aspect of the present application provides a method for inhibiting lithium deposition on the surface of an anode sheet in a lithium ion battery, the method comprising:
  • anode sheet including a current collector and an anode active material layer on at least one surface of the current collector
  • a fourth aspect of the present application provides a battery module including the lithium-ion battery according to the present application.
  • a fifth aspect of the present application provides a battery pack including the battery module of the present application.
  • a sixth aspect of the present application provides an electrical device comprising at least one of the lithium-ion battery, battery module and battery pack of the present application.
  • lithium ions can be preferentially inserted into the underlying active material rather than preferentially aggregated in the surface active material, thereby effectively avoiding lithium deposition on the anode surface in a very simple and economical way.
  • CB value anode/cathode capacity ratio
  • the following effects can also be optionally achieved At least one of: excellent first-effect isoelectric performance, excellent dynamic performance, long service life, convenient manufacturing, improved safety performance, and reduced gas production.
  • FIG. 1 is a cross-sectional view of an anode sheet according to an embodiment of the present invention.
  • Fig. 2a is a photo of the surface of an anode sheet according to a comparative example of the present invention, the anode sheet has no lithium deposition inhibiting layer.
  • Figure 2b is a surface photograph of an anode sheet having a lithium-evolution inhibiting layer comprising lithium iron phosphate according to one embodiment of the present invention.
  • Figure 3 is a charging curve of a comparative example (curve a) and an embodiment (curve b) according to the present invention.
  • FIG. 4 shows the potential boost achieved by providing the lithium deposition inhibiting layer in the embodiment of the invention.
  • FIG. 5 is a schematic diagram of an embodiment of the lithium-ion battery of the present application.
  • FIG. 6 is an exploded view of the lithium ion battery shown in FIG. 5 .
  • FIG. 7 is a schematic diagram of an embodiment of the battery module of the present application.
  • FIG. 8 is a schematic diagram of an embodiment of the battery pack of the present application.
  • FIG. 9 is an exploded view of the battery pack shown in FIG. 8 .
  • FIG. 10 is a schematic diagram of an embodiment of a powered device using the lithium-ion battery of the present application as a power source.
  • the design of the negative electrode active material and its manufacturing method designed in the present application the electrode manufactured using the negative electrode active material, and the lithium ion battery, battery module, battery pack and electrical device comprising the electrode are discussed. Details are described.
  • a “range” disclosed herein is defined in the form of a lower limit and an upper limit, a given range being defined by the selection of a lower limit and an upper limit, the selected lower limit and the upper limit defining the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive, and may be arbitrarily combined, ie, any lower limit may be combined with any upper limit to form a range. For example, if the ranges of 60-120 and 80-110 are listed for a particular parameter, it is to be understood that the ranges of 60-110 and 80-120 are also contemplated.
  • the numerical range "a-b" represents an abbreviated representation of any combination of real numbers between a and b, where both a and b are real numbers.
  • the numerical range "0-5" means that all real numbers between "0-5" have been listed in the text, and "0-5" is just an abbreviated representation of the combination of these numerical values.
  • a parameter is expressed as an integer greater than or equal to 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the like.
  • the "comprising” and “comprising” mentioned in this document indicate an open type, and can also be a closed type.
  • the terms “comprising” and “comprising” can mean that other components not listed may also be included or included, or only the listed components may be included or included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B.” More specifically, the condition “A or B” is satisfied by either of the following: A is true (or present) and B is false (or absent); A is false (or absent) and B is true (or present) ; or both A and B are true (or present).
  • lithium ion battery and “lithium ion secondary battery” are used interchangeably to refer to a lithium ion battery that can be repeatedly charged and discharged.
  • negative electrode and “anode” are used interchangeably to refer to the same electrode in a battery;
  • positive electrode and “cathode” are used interchangeably to refer to the same electrode in a battery.
  • binders are used in both the anode active material layer and the lithium evolution inhibiting layer, and the binders used in each of these two layers may be the same or different from each other, preferably different from each other.
  • the binder used in the lithium evolution inhibiting layer is referred to as "the binder of the lithium evolution inhibiting layer” or “the first binder” in some paragraphs of the present invention.
  • the adhesive in the anode active material layer is referred to as the "adhesive of the anode active material layer" or the "second adhesive". It should be specially pointed out here that the above-mentioned prefixes of "first” and “second” are only for the purpose of distinction, and do not constitute any limiting effect on the importance, order of use, spatial position or amount of the adhesive.
  • the present application develops a novel anode sheet for a lithium-ion battery, the anode sheet comprising:
  • the numerical value of w may be a numerical range obtained by taking any two of the following numerical values as the upper and lower limits, respectively: 0, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.05, 0.06 , 0.07, 0.075, 0.08, 0.085, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 1/3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 2/3, 0.7, 0.75, 0.8, 0.85 , 0.9, 0.95, 0.99, 1; according to a preferred embodiment, the value of w can be 0 or 1.
  • the value of x can be a numerical range in which any two of the following values are obtained as the upper and lower limits, respectively: 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.05, 0.06, 0.07, 0.075, 0.08, 0.085, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 1/3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 2/3, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.99.
  • the numerical value of y may be a numerical range obtained as the upper and lower limits of any two of the following numerical values, respectively: 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.05, 0.06, 0.07 , 0.075, 0.08, 0.085, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 1/3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 2/3, 0.7, 0.75, 0.8, 0.85, 0.9 , 0.95, 0.99.
  • the value of z may be within a range of values obtained as the upper and lower limits of any two of the following values, respectively: 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.05, 0.06, 0.07 , 0.075, 0.08, 0.085, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 1/3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 2/3, 0.7, 0.75, 0.8, 0.85, 0.9 , 0.95, 0.99.
  • the lithium deposition inhibition layer includes at least one of the following materials: LiNi 0.85 Co 0.075 Mn 0.075 O 2 , LiNi 0.8 Co 0.1 Mn 0.1 O 2 , LiNi 0.7 Co 0.15 Mn 0.15 O 2 , LiNi 0.6 Co 0.2 Mn 0.2 O 2 , LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 , LiCoO 2 , LiNiO 2 , LiMnO 2 , LiFeO 2 , LiFePO 4 , LiCoPO 4 , LiNiPO 4 , LiMnPO 4 , Li 4 Ti 5 O 12 .
  • the LiMPO 4 is an olivine-structured composite metal oxide, and the Li 4 Ti 5 O 12 is Composite metal oxides with spinel structure.
  • prior art anode plates generally only include a current collector and an anode active material layer on the surface of the current collector, and do not include a lithium evolution inhibiting layer disposed on the anode active material layer, so
  • the anode active material layer usually contains carbon active material (eg graphite, mesocarbon microspheres, soft carbon, hard carbon, etc.), conductive agent (acetylene black, furnace black, VGCF, carbon nanotube, etc.), adhesive and optional other additives, etc.
  • the prior art anode electrode sheet which only includes a current collector and an anode active material layer, is assembled into a lithium ion battery.
  • lithium ions in the electrolyte will be intercalated into the anode active material layer, but lithium ions are in the anode.
  • the intercalation between the surface and the interior of the active material layer is not balanced, and the enrichment of lithium ions on the surface of the anode active material layer easily leads to the precipitation of lithium dendrites on the surface of the anode electrode sheet, which further brings the risk of short circuit.
  • the method of further disposing a ceramic insulating material layer on the anode active material layer not only cannot effectively eliminate the above-mentioned problem of unbalanced lithium ion intercalation on the surface and inside of the anode active material layer, but will even further lead to the lithium ion battery.
  • the lithium evolution inhibiting layer comprises a first adhesive (that is, the adhesive of the lithium evolution inhibiting layer), for example, the first adhesive is selected from one or more of the following: polyvinylidene fluoride (also known as polyvinylidene fluoride), polytetrafluoroethylene, polychlorotrifluoroethylene.
  • first adhesive is selected from one or more of the following: polyvinylidene fluoride (also known as polyvinylidene fluoride), polytetrafluoroethylene, polychlorotrifluoroethylene.
  • the lithium evolution inhibiting layer does not contain a conductive material. According to another embodiment of the present application, the lithium evolution inhibiting layer does not contain an anode active material (an anode active material used in the anode active material layer). According to another embodiment of the present application, the lithium evolution inhibiting layer contains neither the conductive material nor the anode active material in the anode active material layer. In the above-mentioned embodiments, the lithium deposition inhibiting layer does not contain any conventional carbon conductive materials, such as acetylene black, furnace black, VGCF, carbon nanotube carbon fiber, graphene, carbon black, Ketjen black, Super P, etc.
  • any conventional carbon conductive materials such as acetylene black, furnace black, VGCF, carbon nanotube carbon fiber, graphene, carbon black, Ketjen black, Super P, etc.
  • the lithium deposition inhibiting layer also does not contain any other conductive materials other than carbon commonly used in electrodes.
  • the lithium deposition inhibiting layer does not contain any conventional anode active materials, such as graphite, hard carbon, silicon-based materials, tin-based materials, and the like.
  • the lithium evolution inhibiting layer is only composed of the above-mentioned lithium evolution inhibiting material and the first adhesive, and does not contain other components. By selecting the above composition, the anode sheet of the present application can achieve further optimized performance.
  • the inventors have unexpectedly found that, assuming that the lithium evolution inhibiting layer contains any one or both of any conventional conductive agent and anode active material, the The effect will be greatly reduced, and the effects of inhibiting lithium precipitation and improving the performance of lithium-ion batteries described in this paper may not be ideally achieved.
  • the content of the lithium evolution inhibiting material in the lithium evolution inhibiting layer is 50 to 99.9 wt %, for example, 55 to 99 wt %, or 60 to 98.5 wt%, alternatively 65 to 98 wt%, alternatively 70 to 97.5 wt%, alternatively 80 to 97 wt%, alternatively 90 to 97 wt%, alternatively 95 to 97 wt%.
  • the content of the first adhesive in the lithium evolution inhibiting layer is 0.01 to 50 wt %, for example, 0.02 to 45 wt %, or 0.05 to 40 wt%, alternatively 0.1 to 35 wt%, alternatively 0.5 to 30 wt%, alternatively 0.75 to 20 wt%, alternatively 1 to 15 wt%, alternatively 1.25 to 12.5 wt%, alternatively 1.5 to 10 wt%, alternatively 2 to 7 wt%, alternatively 3 to 6 wt%.
  • the crystallization of lithium on the surface of the anode can be effectively suppressed, and at the same time, there is sufficient sufficient space between the lithium-deposition-inhibiting layer and the underlying anode active material layer. adhesion.
  • the content of the lithium-inhibiting material is lower than the lower limit of the above range, the effect of significantly inhibiting the crystallization of lithium on the surface cannot be achieved, and when the content of the lithium-inhibiting material is higher than the upper limit of the above range, the adhesion of the lithium-deposition-inhibiting layer will be caused. Insufficient, there is a higher risk of delamination.
  • the thickness of the lithium evolution inhibiting layer is 1.8-20 microns, preferably 2.3-15 microns.
  • the thickness of the lithium evolution inhibiting layer may be within a numerical range obtained by combining any two of the following endpoints: 1.8 microns, 1.9 microns, 2 microns, 2.1 microns, 2.2 microns, 2.3 microns, 2.5 microns, 2.6 microns , 2.8 microns, 3 microns, 3.2 microns, 3.5 microns, 3.8 microns, 4 microns, 4.2 microns, 4.3 microns, 4.5 microns, 4.8 microns, 5 microns, 5.5 microns, 6 microns, 6.5 microns, 7 microns, 7.5 microns, 8 microns, 8.5 microns, 9 microns, 9.5 microns, 10 microns, 10.5 microns, 11 microns, 11.5 microns, 12 microns, 1
  • the thickness of the lithium deposition inhibiting layer when the thickness of the lithium deposition inhibiting layer is within the above range, the deposition of lithium on the surface of the anode can be effectively suppressed, and at the same time, sufficient wetting of the electrode sheet by the electrolyte can be ensured.
  • the thickness of the lithium-evolution inhibition layer is less than the lower limit of the above-mentioned numerical range, the effect of inhibiting lithium-evolution at the anode surface cannot be effectively achieved; and when the thickness of the lithium-evolution inhibition layer is greater than the upper limit of the above-mentioned numerical range, it will As a result, the electrolyte cannot fully wet the pole pieces.
  • the thickness of the anode active material layer is 30-340 microns, preferably 55-260 microns.
  • the thickness of the anode active material layer may be within a range of values obtained by combining any two of the following endpoints: 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, 60 microns, 65 microns , 70 microns, 75 microns, 80 microns, 85 microns, 90 microns, 95 microns, 100 microns, 105 microns, 110 microns, 115 microns, 120 microns, 125 microns, 130 microns, 135 microns, 140 microns, 145 microns, 150 microns, 155 microns, 160 microns, 165 microns, 170 microns, 175 microns, 180 microns, 185 microns, 190 microns, 195 microns, 200 micron
  • the thickness of the anode active material layer when the thickness of the anode active material layer is within the above-mentioned range, it can ensure that the battery has a sufficiently high energy density, and at the same time, it can ensure that the electrolyte can fully wet the pole piece.
  • the thickness of the anode active material layer is less than the lower limit of the above numerical range, the energy density of the battery will be too low; and when the thickness of the anode active material layer is greater than the upper limit of the above numerical range, the electrolyte cannot fully wet the pole piece , resulting in an insufficient increase in energy density.
  • the thickness of the lithium evolution inhibiting layer is 2.3-15 microns, and the thickness of the anode active material layer is 55-260 microns;
  • the ratio of the thickness of the lithium deposition inhibiting layer to the thickness of the anode active material layer can be 0.018-0.2, preferably 0.023-0.15, for example, it can be obtained by combining any two of the following values Within the range of values: 0.018, 0.023, 0.033, 0.06, 0.10, 0.11, 0.15, 0.2.
  • the lithium deposition inhibition effect can be optimized, thereby ensuring that the battery achieves excellent first Coulomb efficiency, cycle performance and high energy density.
  • the anode active material layer comprises: an active material selected from one or more of the following: graphite (such as natural graphite or artificial graphite), hard carbon, silicon-based material (such as elemental silicon) , silicon oxide, silicon carbon composite), tin-based materials (such as elemental tin, tin oxide compounds, tin alloys); the second adhesive, which is selected from one or more of the following: styrene-butadiene rubber (SBR), water-soluble Sexually unsaturated resin SR-1B, sodium alginate (SA), polyurethane, polyacrylic acid (PAA), polymethacrylic acid (PMAA), sodium polyacrylate (PAAS), sodium polycarboxymethylcellulose, acrylamide (PAM) ), polyvinyl alcohol (PVA), and carboxymethyl chitosan (CMCS); and a conductive agent selected from one or more of the following: carbon nanotubes, carbon fibers, graphene, carbon black, ketjen black black
  • the potential difference between the lithium deposition inhibiting layer and the anode active material layer is 1-4 volts, for example, 2-2.3 volts.
  • the potential of the lithium evolution inhibiting layer is 1-4 volts higher than the potential of the anode active material layer, preferably 2-2.3 volts higher.
  • the potential difference between the lithium deposition inhibiting layer and the anode active material layer is within the above range, it can ensure that the battery has a sufficiently high energy density and can ensure the normal operation of the battery.
  • the potential difference between the lithium evolution inhibiting layer and the anode active material layer is less than the lower limit of the above-mentioned range of values, the effect of inhibiting lithium deposition on the surface of the anode sheet cannot be effectively achieved;
  • the potential difference is greater than the upper limit of the above-mentioned range of values, the overall normal operation of the anode sheet may be adversely affected.
  • the current collector is a metal foil, a metal alloy foil, a polymer sheet with a metal coating, or a polymer sheet with a metal alloy coating; wherein the metal foil and the metal coating
  • the metal in the metal alloy is selected from copper, silver, iron, titanium, nickel; the metal alloy in the metal alloy foil and the metal alloy coating is selected from copper alloy, nickel alloy, titanium alloy, silver alloy, iron alloy;
  • the polymer sheet The material is selected from polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene and mixtures and copolymers thereof.
  • the negative electrode can be prepared by using an anode active material, a conductive agent, a binder (ie, the binder or the second binder for the anode active layer) and other optional auxiliary and dispersing agents (eg N-methylpyrrolidone (NMP) or deionized water) to form a slurry, the slurry is coated on a current collector, and then dried to form an anode active material layer, which can then contain a lithium evolution inhibiting material.
  • NMP N-methylpyrrolidone
  • a lithium evolution inhibiting layer slurry of a binder (ie, the binder for the lithium evolution inhibiting layer or the first binder) and a dispersant is coated on the anode active material layer, followed by drying to form the lithium evolution inhibiting layer.
  • a binder ie, the binder for the lithium evolution inhibiting layer or the first binder
  • a dispersant is coated on the anode active material layer, followed by drying to form the lithium evolution inhibiting layer.
  • other adjuvants optionally included in the anode active material layer may be thickeners (eg, sodium carboxymethyl cellulose CMC-Na), PTC thermistor materials, and the like.
  • the anode/negative electrode tab does not exclude other additional functional layers.
  • the anode/negative pole piece may further include a conductive primer layer (eg, composed of a conductive agent and a binder) disposed between the negative electrode current collector and the anode active material layer.
  • FIG. 1 shows an anode/negative electrode sheet formed according to an embodiment of the present invention, in which an anode active material layer and a lithium evolution inhibiting layer are respectively formed on both surfaces of a central current collector.
  • the anode active material layer and the lithium evolution inhibiting layer may be formed only on one surface of the current collector.
  • the lithium evolution inhibiting layer completely covers the entire outer surface of the anode active material layer (the surface of the anode active material layer opposite to the current collector).
  • a lithium ion secondary battery which includes a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte, and the like.
  • lithium ions are intercalated and extracted back and forth between the positive electrode and the negative electrode as active ions.
  • the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
  • the negative pole piece (anode pole piece) used therein is the negative pole/anode pole piece of the application.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector and including a positive electrode active material.
  • the positive electrode current collector has two opposite surfaces in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector, for example, the metal foil may be an aluminum foil, and the composite current collector may include a polymer material base layer and a composite current collector formed on the high A metal layer on at least one surface of the base layer of molecular material.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) Glycol ester PET, polybutylene terephthalate PBT, polystyrene PS, polyethylene PE and its copolymers etc.
  • the positive electrode active material can be a positive electrode active material for a lithium ion secondary battery known in the art. These positive electrode active materials may be used alone or in combination of two or more.
  • the positive electrode film layer also optionally includes a binder.
  • adhesives that can be used in the positive film layer may include one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer compound, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer compound vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the positive electrode film layer may also optionally contain a conductive agent.
  • the conductive agent used in the positive electrode film layer may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • a positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing a positive electrode sheet, such as a positive electrode active material, a conductive agent, a binder, and any other components, in a solvent (such as N-methyl methacrylate) pyrrolidone), a uniform positive electrode slurry is formed; the positive electrode slurry is coated on the positive electrode current collector, and the positive electrode sheet can be obtained after drying, cold pressing and other processes.
  • a solvent such as N-methyl methacrylate
  • the electrolyte acts to conduct ions between the positive/cathode and negative/anode sheets.
  • the electrolyte may be selected from at least one of solid electrolytes and liquid electrolytes (ie, electrolytes).
  • the anode electrode sheet in the present application has a specially designed structure of current collector+anode active material layer+lithium evolution inhibiting layer, and the materials in the lithium evolution inhibiting layer are specially designed, such that
  • the capacity ratio of anode and cathode in the lithium ion secondary battery of the present invention does not significantly increase, for example, the capacity ratio (CB value) of anode and cathode is 1.07 to 1.01, or 1.07 to 1.03, or any two of the following values Within the range of values combined: 1.07, 1.06, 1.05, 1.04, 1.03, 1.02, 1.01.
  • the CB value mentioned above represents the ratio of the negative electrode/anode capacity and the positive electrode/cathode capacity in the battery, which can be calculated according to the following formula:
  • CB value (anode surface density ⁇ anode active material ratio ⁇ anode active material discharge specific capacity) / (cathode surface density ⁇ cathode active material ratio ⁇ cathode active material discharge specific capacity)
  • the specific CB value of each battery is accurately determined based on the type and amount of active materials applied on the specifically selected positive and negative electrodes (eg, based on the thickness of the pole pieces, the proportion of active materials contained, etc.).
  • the capacity ratio of the anode and the cathode when the capacity ratio of the anode and the cathode is within the above range, an appropriate battery energy density can be achieved, and lithium precipitation on the surface of the anode sheet can be effectively suppressed.
  • the capacity ratio of the anode to the cathode in the secondary battery is higher than the upper limit of the above numerical range, the energy density of the battery will be significantly reduced; and when the capacity ratio of the anode to the cathode in the lithium ion secondary battery of the present invention is lower than the above numerical range. When the lower limit is reached, lithium precipitation will easily occur on the surface of the anode sheet.
  • the electrolyte is an electrolyte.
  • the electrolyte solution includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), bisfluorosulfonylidene Lithium Amide (LiFSI), Lithium Bistrifluoromethanesulfonimide (LiTFSI), Lithium Trifluoromethanesulfonate (LiTFS), Lithium Difluorooxalate Borate (LiDFOB), Lithium Dioxalate Borate (LiBOB), Lithium Difluorophosphate One or more of (LiPO 2 F 2 ), lithium difluorodioxalate phosphate (LiPF 6 ), lithium
  • the solvent may be selected from one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), Dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), formic acid Methyl propionate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP) , methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS)
  • the content of the solvent is 60-99% by weight, such as 65-95% by weight, or 70-90% by weight, or 75-89% by weight , or 80-85% by weight. In some embodiments, based on the total weight of the electrolyte, the content of the electrolyte is 1-40% by weight, such as 5-35% by weight, or 10-30% by weight, or 11-25% by weight , or 15-20% by weight.
  • the electrolyte may also optionally contain additives.
  • the additives may include one or more of the following: negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performance of the battery, such as additives to improve battery overcharge performance, additives to improve battery high temperature performance, Additives to improve low temperature performance of batteries, etc.
  • the lithium ion secondary battery further includes a separator, which separates the anode and cathode electrodes of the lithium ion secondary battery, and provides selection of substances of different types, sizes and charges in the system
  • the separator can insulate the electrons, physically isolate the positive and negative active materials of the lithium ion secondary battery, prevent the internal short circuit and form an electric field in a certain direction, and at the same time enable the ions in the battery to pass through the isolation.
  • the membrane moves between the positive and negative electrodes.
  • the materials used to prepare the separator may include one or more of glass fibers, non-woven fabrics, polyethylene, polypropylene and polyvinylidene fluoride.
  • the separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer can be the same or different.
  • the anode electrode sheet, cathode electrode sheet and separator described above may be fabricated into an electrode assembly through a winding process or a lamination process.
  • the lithium-ion battery can include an outer package that can be used to encapsulate the electrode assembly and electrolyte described above.
  • the outer packaging of the lithium-ion battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, and the like.
  • the outer package of the lithium-ion battery may be a soft package, such as a bag-type soft package.
  • the material of the soft bag can be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc.
  • FIG. 5 is a lithium ion battery 5 of a square structure as an example.
  • FIG. 6 shows an exploded view of the lithium-ion battery 5 of FIG. 5,
  • the outer package may include a case 51 and a cover plate 53, the case 51 may include a bottom plate and a side plate connected to the bottom plate, the bottom plate and the side plate Enclosed to form a receiving cavity.
  • the housing 51 has an opening that communicates with the accommodating cavity, and a cover plate 53 can cover the opening to close the accommodating cavity.
  • the positive pole piece, the negative pole piece and the separator can be rolled or laminated to form the electrode assembly 52 , the electrode assembly is packaged in the accommodating cavity, and the electrolyte is infiltrated in the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the lithium ion battery 5 may be one or more.
  • lithium-ion batteries can be assembled together to form a battery module, the battery module contains two or more lithium-ion batteries, the specific number depends on the application of the battery module and the individual battery module group parameters.
  • FIG. 7 shows the battery module 4 as an example.
  • a plurality of lithium-ion batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of lithium ion batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having an accommodating space, and the plurality of lithium ion batteries 5 are accommodated in the accommodating space.
  • two or more of the above-mentioned battery modules can be assembled into a battery pack, and the number of battery modules contained in the battery pack depends on the application of the battery pack and the parameters of a single battery module.
  • the battery pack can include a battery box and a plurality of battery modules arranged in the battery box, the battery box includes an upper box body and a lower box body, the upper box body can be covered on the lower box body and is well matched with it, and is formed for accommodating Enclosed space for battery modules. Two or more battery modules can be arranged in the battery box in a desired manner.
  • the battery pack 1 may include a battery case and a plurality of battery modules 4 disposed in the battery case.
  • the battery box includes an upper box body 2 and a lower box body 3 .
  • the upper box body 2 is used to cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • the plurality of battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device comprising at least one of the above-mentioned lithium ion battery, battery module, or battery pack.
  • the lithium-ion battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device.
  • the electrical devices include but are not limited to mobile digital electrical 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, etc.) , electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • FIG. 10 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module can be used.
  • the electrical device may be a mobile phone, a tablet computer, a notebook computer, and the like.
  • the electric device usually requires thinness and lightness, and a lithium-ion battery can be used as a power source.
  • the raw materials used in this application are all analytically pure, and the water is all deionized water.
  • lithium-evolution suppressing materials are used to synthesize the anode-plate lithium-evolution suppressing layer:
  • Lithium deposition inhibiting material supplier LiFePO4 Xiamen Tungsten Industry Co., Ltd. LiNi 0.5 Co 0.2 Mn 0.3 O 2 Hunan Bangpu Circulation Technology Co., Ltd. LiNi 1/3 Co 1/3 Mn 1/3 O 2 Hunan Bangpu Circulation Technology Co., Ltd. LiNi 0.8 Co 0.1 Mn 0.1 O 2 Hunan Bangpu Circulation Technology Co., Ltd. LiCoO 2 Xiamen Tungsten Industry Co., Ltd. Li 2 Mn 2 O 4 (ie LiMnO 2 ) Xiamen Tungsten Industry Co., Ltd. Li 4 Ti 5 O 12 Shenzhen Betterray Energy Materials Co., Ltd.
  • an anode sheet comprising a lithium evolution inhibiting layer of LiFePO 4 was synthesized and a lithium ion battery including the anode sheet was characterized.
  • LiFePO 4 and polyvinylidene fluoride as a binder were fully stirred and mixed in deionized water at a weight ratio of 97:3 to form a uniform slurry with a solid content of 30% by weight.
  • the slurry was coated on the previously formed anode active material layer, transferred into an oven, and dried at a temperature of 150°C for 60 minutes to form a dry coating with a thickness of 15 microns (i.e., a lithium deposition inhibiting layer).
  • the obtained ratio of the thickness of the lithium deposition inhibiting layer to the thickness of the anode active material layer was equal to 0.1.
  • Cold pressing was performed at a pressure of 60 tons using a roll press to obtain an anode sheet.
  • Figure 2b shows an optical photograph of the surface of the anode sheet.
  • the dry coating thickness is 130 ⁇ m.
  • the CB value of the anode and cathode electrodes is 1.07.
  • a PE film with a thickness of 16 ⁇ m was used as the separator.
  • Ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1, and then the fully dried lithium salt LiPF 6 was uniformly dissolved in the above mixed solvent. To obtain an electrolyte solution, wherein the concentration of LiPF 6 is 1 mol/L.
  • the above-mentioned positive electrode sheets, separators, and negative electrode sheets were stacked and wound in sequence to form a wound stack structure with a size of 5.1 cm ⁇ 4.4 cm ⁇ 0.5 cm.
  • the wound laminate structure was placed in an aluminum casing, 150 g of an electrolyte was injected into it and packaged, and a lithium ion secondary battery was obtained after standing, chemical formation, and aging.
  • the prepared cells were first allowed to stand for 6 hours, then installed in a charge-discharge tester purchased from Wuhan Blue Electric, and measured at 45°C under the following conditions: firstly charged to 3.4V at 0.1C, and then allowed to stand for 15 minutes, It was then charged to 3.8V at 0.33C and the results obtained are shown in curve b in Figure 3.
  • Example 1 the steps of Example 1 were basically repeated to manufacture an anode electrode sheet and a lithium ion battery, the only difference being that after the anode active material layer was formed, no lithium deposition inhibiting layer was further provided on the anode active material layer.
  • Figure 2a shows an optical photograph of the surface of the anode sheet.
  • the CB value of the anode and cathode electrodes is 1.07.
  • the charging curve thereof was tested at room temperature in the same manner as in Example 1, and the result is shown as curve a in FIG. 3 .
  • the voltage difference curve shown in FIG. 4 can be obtained by subtracting the voltage values of the two curves a and b in FIG. 3 .
  • the voltage difference curve reflects the voltage difference exhibited by the anode electrodes of Example 1 and Comparative Example 1. Specifically, It can be observed from the curve in Figure 4 that after coating the surface of the anode active layer (containing graphite as the anode active material) with a lithium deposition inhibitory layer containing LiFePO 4 , the surface anode potential increases by 200-620 mV under different SOCs.
  • the potential increase reaction shown here is the overall potential change of the anode in Example 1 in which the lithium evolution inhibition layer and the anode active material layer are used as the anode as a whole relative to Comparative Example 1 without the lithium deposition inhibition layer in the anode.
  • the potential difference between the lithium deposition inhibiting layer and the anode active material layer is within the range of 1-4 volts as defined in this application, and is about 3.2V.
  • Example 2 Using the anode and cathode sheets (CB value 1.07) prepared in Example 1, the battery was fabricated in the same manner as in Example 1, except that a copper wire with a diameter of 200 microns was set on the anode surface, Change the copper wire to lead the electrode and weld the nickel sheet as the third electrode (reference electrode) to obtain a three-electrode battery, and verify the lithium deposition window at different magnifications at room temperature by the following methods:
  • Lithium is plated on the surface of the copper wire, the positive electrode of the charge-discharge tester is connected to the cathode of the battery, and the negative electrode of the charge-discharge tester is connected to the copper wire, and charged for two hours at a current of 20 microamperes, so that the lithium ions in the cathode are deposited on the copper wire. on the wire. Then, the positive electrode of the charge-discharge tester was connected to the battery anode, and the negative electrode was connected to a copper wire, and charged for two hours at a current of 20 microamps, so that the lithium ions in the anode were deposited on the copper wire.
  • Example 2 the steps of Example 2 were basically repeated to manufacture a three-electrode battery, the only difference being that the anode electrode sheet of Comparative Example 1 was used, and no lithium deposition inhibiting layer was further provided on the anode active material layer.
  • SOC state of charge
  • Table 1 Shown is the SOC corresponding to different rate batteries when the anode potential is zero.
  • Example 2 The steps of Example 2 were repeated to construct a three-electrode battery and measure the SOC at different rates (0.33C, 1C, 3C, 5C) at room temperature (each experiment was performed on three cells under the same conditions, and the test results were Take the average value of three cell data) to investigate its lithium precipitation window.
  • the difference between Example 3 and Example 1 is that by slightly adjusting the amount of cathode active material, the CB values are changed to 1.01, 1.03 and 1.03 respectively. 1.05.
  • the SOC at different rates was verified at room temperature to characterize the lithium deposition window on the surface of the anode sheet in the battery, and the results are shown in Table 2.
  • Comparative Example 2 The steps of Comparative Example 2 were repeated to construct a three-electrode battery and measure the SOC at different magnifications (0.33C, 1C, 3C, 5C) at room temperature according to the test technique described in Comparative Example 2 (each experiment was performed under the same conditions at The test results were carried out on three cells, and the test results were taken as the average value of the data of the three cells) to investigate the lithium precipitation window.
  • the difference between the comparative example 3 and the comparative example 2 is that by slightly adjusting the amount of cathode active material
  • the CB values in the experiments were changed to 1.01, 1.03 and 1.05, respectively.
  • the SOC at different rates was verified at room temperature to characterize the lithium deposition window on the surface of the anode plate in the battery.
  • the results are shown in Table 2.
  • the experimental results shown in Table 2 are for the CB with different CB values when the anode potential is zero. SOC of Li-ion battery.
  • Example 2 the steps of Example 1 were repeated to synthesize a lithium ion battery (CB value 1.07).
  • the charge-discharge cycle was carried out at room temperature and at a rate of 1C.
  • the charge-discharge voltage ranged from 2.8V to 4.35V and the charge current was 1C.
  • the specific process was as follows: (1) Charge to 4.35V at a current of 1C and measure the process.
  • Example 4 has higher first Coulomb efficiency and better cycle performance. Since the difference between Example 4 and Comparative Example 4 is only whether a lithium deposition inhibiting layer is provided on the anode surface, it is shown that the method of providing a lithium deposition inhibiting layer in the present invention can significantly improve the above performance.
  • Example 5 the procedure of Example 1 was repeated to produce a lithium ion battery.
  • the difference is only in that the thickness of the anode active material layer is changed to 20, 30, 55, 100, 260, 340 and 400 microns by adjusting the coating amount of the anode active material layer, and the lithium deposition formed on the anode active material layer is inhibited
  • the layer thickness was 6 microns, and in this example, the ratio of the thickness of the lithium evolution inhibiting layer to the thickness of the anode active material layer was equal to 0.3, 0.2, 0.11, 0.06, 0.023, 0.018 and 0.015, respectively.
  • the coating thickness of the cathode active material layer was changed proportionally to keep the CB value of the battery at 1.07.
  • the charge-discharge cycle test was performed at room temperature 1C rate, and the first coulombic efficiency of the battery, the energy density after 500 cycles were calculated, and the number of cycles required for the battery capacity to decay to 80% of the initial capacity was measured. The results are shown in Table 4.
  • Comparative Example 5 the procedure of Comparative Example 1 was repeated to produce a lithium ion battery.
  • the only difference is that the thickness of the anode active material layer is changed to 30, 55, 100, 260 and 340 microns by adjusting the coating amount of the anode active material layer.
  • the coating thickness of the cathode/cathode active material layers was changed proportionally to keep the CB value of the battery at 1.07.
  • the charge-discharge cycle test was performed at room temperature 1C rate, and the first coulombic efficiency of the battery, the energy density after 500 cycles were calculated, and the number of cycles required for the battery capacity to decay to 80% of the initial capacity was measured. The results are shown in Table 4.
  • Example 5 when the thickness of the anode active material layer of Example 5 is in the range of 30-340 ⁇ m and the ratio of the thickness of the lithium evolution inhibiting layer to the thickness of the anode active material layer is in the range of 0.018 to 0.2 Within the range, the battery of Example 5 is significantly better than the corresponding performance of Comparative Example 5 in terms of the first Coulomb efficiency and capacity fading properties.
  • Example 5 when the thickness of the anode active material layer was in the range of 55-260 micrometers, further improvement in the cycle performance of the battery could be achieved.
  • the thickness of the anode active material layer is 100 ⁇ m to achieve particularly optimized battery cycle performance.
  • Example 5 produced the lithium-ion battery still has significantly better first Coulomb efficiency and battery capacity fade resistance (the number of cycles required for the battery capacity to decay to 80% of the initial capacity), but not as good as the above-mentioned preferred
  • the battery with the thickness of the anode active material layer and the thickness ratio of the lithium deposition inhibiting layer/anode active material layer achieved an excellent energy density after 500 cycles.
  • Example 6 the procedure of Example 1 was repeated to produce a lithium ion battery.
  • the only difference is that by adjusting the coating amount of the anode active material layer to keep the thickness of the anode active material layer at 100 microns, and by controlling the amount of the lithium evolution inhibiting layer slurry applied on the anode active material layer, the The thickness of the lithium-evolution inhibition layer was adjusted to 30, 20, 11, 6, 2.3, 1.8 and 1.5 microns (the thickness of the lithium-evolution inhibition layer was equal to 0.3, 0.2, 0.11, 0.06, 0.023, 0.018, 0.015).
  • the coating thickness of the cathode/cathode active material layer was selected in proportion to the anode active material thickness to maintain the CB value of the cell at 1.07.
  • the charge-discharge cycle test was performed at room temperature 1C rate, and the first coulombic efficiency of the battery, the energy density after 500 cycles were calculated, and the number of cycles required for the battery capacity to decay to 80% of the initial capacity was measured. The results are shown in Table 5.
  • the change in the thickness of the lithium deposition inhibiting layer in Example 6 also affects the cycle performance of the battery.
  • the thickness of the lithium evolution inhibiting layer is 1.8-20 ⁇ m, and the ratio of the thickness of the lithium evolution inhibiting layer to the thickness of the anode active material layer is in the range of 0.018 to 0.2, the lithium ion battery has both the first Coulomb efficiency and the capacity fading property. More satisfactory, when the thickness of the lithium evolution inhibition layer is 2.3-15 ⁇ m, and the ratio of the thickness of the lithium evolution inhibition layer to the thickness of the anode active material layer is in the range of 0.023 to 0.15, further improvement of the battery cycle performance can be achieved. .
  • the thickness of the lithium-evolution inhibition layer can achieve a particularly optimized first-time Coulomb efficiency and cycle performance under the condition of 6 ⁇ m.
  • the thickness of the lithium evolution inhibiting layer of the battery in Example 6 is outside the range of 1.8-20 ⁇ m and the ratio of the thickness of the lithium evolution inhibiting layer to the thickness of the anode active material layer is between 0.018 and 0.2 Outside the range, the lithium-ion battery can still obtain relatively good results in terms of the first Coulomb efficiency and the battery capacity decay resistance (the number of cycles required for the battery capacity to decay to 80% of the initial capacity) (for example, compared with those shown in Table 4 above).
  • the lithium-evolution-inhibiting layer of this thickness can still exert the lithium-evolution-inhibiting effect to a certain extent, but it does not have the above-mentioned preferred thickness of the lithium-evolution-inhibiting layer.
  • Excellent energy density after 500 cycles is achieved as in the battery with the thickness ratio of the lithium deposition inhibiting layer/anode active material layer.
  • Example 7 the production of negative electrode/anode was carried out according to the following steps: graphite, adhesive polyurethane, thickener sodium carboxymethyl cellulose (CMC-Na) and conductive agent carbon fiber were mixed in a ratio of 96.5:1.35:1.35:0.8 The weight ratio of deionized water is fully stirred and mixed to form a uniform slurry with a solid content of 30% by weight; the slurry is coated on the surface of the negative electrode current collector copper foil, and transferred into an oven at 150 ° C. Drying at the same temperature for 60 minutes to form a dry coating (ie, anode active material layer) with a thickness of 120 ⁇ m.
  • a dry coating ie, anode active material layer
  • Li 4 Ti 5 O 12 , LiFePO 4 , LiCoO 2 , Li 2 Mn 2 O 4 , LiNi 0.5 Co 0.2 Mn 0.3 O 2 , LiNi 1/3 Co 1/3 Mn 1/ 3 O 2 , LiNi 0.8 Co 0.1 Mn 0.1 O 2 and polytetrafluoroethylene as a binder were fully stirred and mixed in deionized water at a weight ratio of 97.1:2.9 to form a uniform slurry with a solid content of 30% by weight.
  • the slurry was coated on the previously formed anode active material layer, transferred into an oven, and dried at a temperature of 150° C.
  • the ratio of the thickness of the lithium deposition inhibiting layer to the thickness of the anode active material layer employed in this example was equal to 0.033.
  • Cold pressing was performed at a pressure of 60 tons using a roll press to obtain an anode sheet.
  • lithium ion cells were fabricated following the same procedure as Example 1, with the thickness of the cathode active material in the cathode sheet adjusted to maintain the CB value at 1.07 in all cells.
  • the charge-discharge cycle test was performed at room temperature 1C rate, and the first coulombic efficiency of the battery, the energy density after 500 cycles were calculated, and the number of cycles required for the battery capacity to decay to 80% of the initial capacity was measured. The results are shown in Table 6.
  • Comparative Example 6 the procedure of Comparative Example 1 was repeated to produce a lithium ion battery. The difference is only that the thickness of the anode active material layer is changed to 120 ⁇ m by adjusting the coating amount of the anode active material layer. At the same time, the coating thickness of the cathode/cathode active material layers was changed proportionally to keep the CB value of the battery at 1.07.
  • the charge-discharge cycle test was performed at room temperature 1C rate, and the first coulombic efficiency of the battery, the energy density after 500 cycles were calculated, and the number of cycles required for the battery capacity to decay to 80% of the initial capacity was measured. The results are shown in Table 6.
  • a lithium ion battery was produced in the same manner as in Example 7, except that the solid raw material used for the production of the lithium deposition inhibiting layer was a mixture of Li 4 Ti 5 O 12 , carbon black and polytetrafluoroethylene (97.1:1:1.9) .
  • the CB value in the battery remained at 1.07.
  • the charge-discharge cycle test was performed at room temperature 1C rate, and the first coulombic efficiency of the battery, the energy density after 500 cycles were calculated, and the number of cycles required for the battery capacity to decay to 80% of the initial capacity was measured. The results are shown in Table 6.
  • a lithium ion battery was fabricated in the same manner as in Example 8, except that the solid raw material used to fabricate the lithium evolution inhibiting layer was a mixture of LiFePO 4 , carbon black and polytetrafluoroethylene (97.1:1:1.9).
  • the CB value in the battery remained at 1.07.
  • the charge-discharge cycle test was performed at room temperature 1C rate, and the first coulombic efficiency of the battery, the energy density after 500 cycles were calculated, and the number of cycles required for the battery capacity to decay to 80% of the initial capacity was measured. The results are shown in Table 6.
  • the thickness of the lithium deposition inhibition layer is 1.8-20 microns, preferably 2.3-15 microns, more preferably 4-15 microns
  • the thickness of the anode active material layer is 30-340 microns, preferably 55-260 microns, more preferably 100-150 microns
  • the thickness of the lithium deposition inhibiting layer and the thickness of the anode active material layer are 0.018-0.20, preferably 0.023-0.11, more preferably 0.033-0.10 , which can achieve extremely excellent first Coulomb efficiency and cycle performance.
  • Example 7 The steps of Example 7 were repeated to prepare anode sheets and lithium ion batteries using a variety of different lithium deposition inhibiting chromatographic lithium inhibiting materials. Test the gas production performance at room temperature (by connecting the liquid injection hole of the 1C fully charged cell to the air pressure flowmeter for air pressure detection) and safety performance (the diameter of a 1mm stainless steel needle is 0.1mm/s from the large aluminum shell Insert the cells to 2mm and 5mm). The results are shown in Table 7.
  • Comparative Example 6 The steps of Comparative Example 6 were repeated to manufacture a lithium ion battery. Test the gas production performance at room temperature (by connecting the liquid injection hole of the 1C fully charged cell to the air pressure flowmeter for air pressure detection) and safety performance (the diameter of a 1mm stainless steel needle is 0.1mm/s from the large aluminum shell at a speed of 0.1mm/s) Insert the cells to 2mm and 5mm). The results are shown in Table 7.
  • Comparative Example 7 The steps of Comparative Example 7 were repeated to manufacture a lithium ion battery. Test the gas production performance at room temperature (by connecting the liquid injection hole of the 1C fully charged cell to the air pressure flowmeter for air pressure detection) and safety performance (the diameter of a 1mm stainless steel needle is 0.1mm/s from the large aluminum shell at a speed of 0.1mm/s) Insert the cells to 2mm and 5mm). The results are shown in Table 7.
  • Comparative Example 8 The steps of Comparative Example 8 were repeated to manufacture a lithium ion battery. Test the gas production performance at room temperature (by connecting the liquid injection hole of the 1C fully charged cell to the air pressure flowmeter for air pressure detection) and safety performance (the diameter of a 1mm stainless steel needle is 0.1mm/s from the large aluminum shell at a speed of 0.1mm/s) Insert the cells to 2mm and 5mm). The results are shown in Table 7.
  • the potential difference between the lithium deposition inhibiting layer and the anode active material layer selected in all the examples of this application is in the range of 1-4 volts.

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Abstract

本申请提供了一种锂离子电池的阳极极片及其应用，所述阳极极片包括集流体、阳极活性材料层和特别设计的析锂抑制层，本发明的阳极极片能够以经济而简便的方式有效地避免阳极极片表面的析锂，同时有效地降低阳极和阴极的容量比、提升锂离子电池的首次库伦效率、循环寿命、能量密度和安全性。

Description

一种锂离子电池的阳极极片及其应用 技术领域
本申请涉及电池领域，更具体来说涉及用于锂离子电池的阳极极片，还涉及包含该阳极极片的锂离子电池、电池模组、电池包和用电装置，以及一种抑制锂离子电池中阳极极片表面析锂的方法。
背景技术
随着近些年来相关领域的发展，可充电电池(也被称为二次电池)被越来越多地应用于诸如日用消费品、新能源汽车、大规模储能、航空航天、船舶、重型机械之类的高科技、高强度、高要求的领域，甚至在这些领域被用作主要动力和能源供应设备。在开发的各种不同的二次电池中，锂离子二次电池由于具有优异的性能而广受关注。但是锂离子二次电池本身也存在迄今为止始终无法解决的一些重大缺陷，例如在锂离子电池的日常充放电使用过程中，电解质中的锂离子嵌入阳极的过程并不是均匀进行的，由此在长期的循环之后有可能会在阳极表面产生金属锂枝晶，严重的情况下这些枝晶有可能会穿透隔膜，进而存在发生诸如电池短路、膨胀、燃烧、甚至爆炸等安全事故的风险。为了避免上述问题，现有技术进行了一些尝试，例如在阳极表面上设置陶瓷质绝缘层，但是这种做法并不能真正解决阳极的石墨层表面析锂而石墨层底部无法嵌锂的问题，只是在一定程度上降低枝晶的危害；非但无法真正有效地避免阳极表面析出锂枝晶的问题，还会导致其他的问题，例如电池极化增加、能量密度降低、循环寿命短、充放电电压平台不稳定等。人们迫切希望能够解决上述问题。
发明内容
为了解决现有技术中存在的上述问题，申请人进行了深入的研究，出人意料地发现通过采用具有专门设计的析锂抑制层的阳极极片，能够使锂离子优先嵌入到底层活性材料中而非优先聚集于析锂抑制层，以非常简单而经济的方式 有效地避免阳极表面析锂的现象，同时可以降低锂离子电池的阳极/阴极容量比(CB值，Cell Balance值)，大幅提升锂离子电池的首次库伦效率、能量密度，实现理想的循环寿命和充放电电压平台。
本申请的第一个方面提供了一种用于锂离子电池的阳极极片，该阳极极片包括：
i)集流体；
ii)位于所述集流体至少一个表面上的阳极活性材料层；以及
iii)位于所述阳极活性材料层上的析锂抑制层，所述析锂抑制层包含以下析锂抑制材料中的至少一种：LiNi xCo yMn zFe wO 2、LiMPO 4、LiMO 2和Li 4Ti 5O 12，其中0≤x≤1，0≤y≤1，0≤z≤1，0≤w≤1，且x+y+z+w＝1，M选自Fe、Co、Ni、Mn或其组合。
在本申请第一个方面的一个实施方式中，所述析锂抑制层包含以下析锂抑制材料中的至少一种：LiNi 0.85Co 0.075Mn 0.075O 2、LiNi 0.8Co 0.1Mn 0.1O 2、LiNi 0.7Co 0.15Mn 0.15O 2、LiNi 0.6Co 0.2Mn 0.2O 2、LiNi 0.5Co 0.2Mn 0.3O 2、LiNi 1/3Co 1/3Mn 1/3O 2、LiCoO 2、LiNiO 2、LiMnO 2、LiFeO 2、LiFePO 4、LiCoPO 4、LiNiPO 4、LiMnPO 4、Li 4Ti 5O 12。
在本申请第一个方面的另一个实施方式中，所述LiNi xCo yMn zFe wO 2是层状结构的复合金属氧化物，所述LiMPO 4是橄榄石结构的化合物，所述Li 4Ti 5O 12是尖晶石结构的化合物。
在本申请第一个方面的另一个实施方式中，所述析锂抑制层包含第一胶粘剂，所述第一胶粘剂选自以下的一种或多种：聚偏二氟乙烯、聚四氟乙烯、聚三氟氯乙烯。
在本申请第一个方面的另一个实施方式中，所述析锂抑制层不含导电材料。
在本申请第一个方面的另一个实施方式中，所述析锂抑制层不含碳基导电材料。在本申请第一个方面的另一个实施方式中，所述析锂抑制层不含以下任意一种碳基导电材料：石墨、中间相碳微球、软碳、硬碳、碳纳米管、碳纤维、石墨烯、炭黑、科琴黑、Super P、乙炔黑、炉黑、气相生长碳纤维(VGCF)，上述这些碳基导电材料均未包含在所述析锂抑制层中。
在本申请第一个方面的另一个实施方式中，所述析锂抑制层的厚度为1.8-20微米；所述阳极活性材料层的厚度为30-340微米，所述析锂抑制层的厚度为所述阳极活性材料层的厚度的0.018倍-0.2倍。
在本申请第一个方面的另一个实施方式中，所述析锂抑制层的厚度为2.3-15微米；所述阳极活性材料层的厚度为55-260微米，所述析锂抑制层的厚度为所述阳极活性材料层的厚度的0.023倍-0.11倍。
在本申请第一个方面的另一个实施方式中，所述阳极活性材料层包含：活性材料，其选自以下的一种或多种：石墨、硬碳、硅基材料、锡基材料；第二胶粘剂，其选自以下的一种或多种：丁苯橡胶、水溶性不饱和树脂SR-1B、海藻酸钠、聚氨酯、聚丙烯酸、聚甲基丙烯酸、聚丙烯酸钠、聚羧甲基纤维素钠、丙烯酰胺、聚乙烯醇、和羧甲基壳聚糖；导电剂：碳纳米管、碳纤维、石墨烯、炭黑、科琴黑、Super P。
在本申请第一个方面的另一个实施方式中，所述析锂抑制层与所述阳极活性材料层的电势差为1-4伏。
在本申请第一个方面的另一个实施方式中，所述集流体为金属箔、金属合金箔、具有金属涂层的聚合物片材或者具有金属合金涂层的聚合物片材；其中所述金属箔和金属涂层中的金属选自铜、银、铁、钛、镍；所述金属合金箔和金属合金涂层中的金属合金选自铜合金、镍合金、钛合金、银合金、铁合金；所述聚合物片材选自聚丙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚苯乙烯、聚乙烯及其混合物和共聚物。
本申请的第二个方面提供了一种锂离子电池，其包括阴极极片、电解质和本申请的阳极极片。
在本申请第二个方面的一个实施方式中，所述阳极极片和所述阴极极片的容量比为1.07至1.01，例如为1.07至1.03。
本申请的第三个方面提供了一种抑制锂离子电池中阳极极片表面析锂的方法，该方法包括：
提供阳极极片，该阳极极片包括集流体和位于所述集流体至少一个表面上的阳极活性材料层；
在所述阳极活性材料层的表面上设置析锂抑制层，所述析锂抑制层包含以 下材料中的至少一种：LiNi xCo yMn zFe wO 2、LiMPO 4、Li 2M 2O 4和Li 4Ti 5O 12，其中0≤x≤1，0≤y≤1，0≤z≤1，0≤w≤1，且x+y+z+w＝1，M选自Fe、Co、Ni、Mn或其组合。
本申请的第四个方面提供了一种电池模组，包括根据本申请的锂离子电池。
本申请的第五个方面提供了一种电池包，包括本申请的电池模组。
本申请的第六个方面提供了一种用电装置，其包括本申请的锂离子电池、电池模组以及电池包中的至少一种。
有益效果
本申请通过在阳极极片中专门设计析锂抑制层，能够使锂离子优先嵌入到底层活性材料中而非优先聚集于表层活性材料中，以非常简单而经济的方式有效地避免阳极表面析锂的现象，同时可以降低电池的阳极/阴极容量比(CB值)，大幅提升锂离子电池的首次库伦效率、能量密度，实现理想的循环寿命和充放电电压平台，还可以任选地实现以下效果中的至少一种：首效等电性能优异、动力学性能极佳、使用寿命长、制造方便、安全性能提高、减少产气等。
附图说明
图1是根据本发明一个实施方式的阳极极片的截面图。
图2a是根据本发明一个比较例的阳极极片的表面照片，该阳极极片没有析锂抑制层。
图2b是根据本发明一个实施例的阳极极片的表面照片，该阳极极片具有包含磷酸铁锂的析锂抑制层。
图3是根据本发明一个比较例(曲线a)和一个实施例(曲线b)的充电曲线。
图4显示了发明实施例通过设置析锂抑制层而实现的电位提升。
图5是本申请锂离子电池的一实施方式的示意图。
图6是图5所示锂离子电池的分解图。
图7是本申请电池模组的一实施方式的示意图。
图8是本申请电池包的一实施方式的示意图。
图9是图8所示电池包的分解图。
图10是使用本申请的锂离子电池用作电源的用电装置的一实施方式的示意图。
在下文的具体实施方式部分中，对本申请设计的负极活性材料及其制造方法、使用该负极活性材料制造的电极以及包含该电极的锂离子电池、电池模组、电池包和用电装置的设计细节进行描述。
具体实施方式
本文所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
在本申请中，如果没有特别的说明，本文所提到的所有实施方式以及优选实施方式可以相互组合形成新的技术方案。
在本申请中，如果没有特别的说明，本文所提到的所有技术特征以及优选特征可以相互组合形成新的技术方案。
在本申请中，如果没有特别的说明，本文所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
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，“一种或几种”中“几种”的含义是两种及两种以上。
在本文的描述中，除非另有说明，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
在本申请中，术语“锂离子电池”和“锂离子二次电池”可互换使用，用于表示能够反复充放电的锂离子电池。在本申请的全文中，术语“负极”和“阳极”可互换使用，指代电池中相同的电极；术语“正极”和“阴极”可互换使用，指代电池中相同的电极。
在本发明的各个实施方式中，在阳极活性材料层和析锂抑制层中均使用了胶粘剂，这两个层中各自使用的胶粘剂可以是彼此相同的或者彼此不同的，优选是彼此不同的。为了区分所述阳极活性材料层和所述析锂抑制层中使用的胶粘剂，在本发明的一些段落中将析锂抑制层中使用的胶粘剂称为“析锂抑制层的胶粘剂”或者“第一胶粘剂”，而将阳极活性材料层中的胶粘剂称为“阳极活性材料层的胶粘剂”或者“第二胶粘剂”。此处需要特别指出的是，上述“第一”和“第二”的前缀仅仅出于区别的目的，而不会对胶粘剂的重要性、使用顺序、空间位置或用量构成任何限定效果。
根据本申请的一个实施方式，本申请开发了一种用于锂离子电池的新颖的阳极极片，该阳极极片包括：
i)集流体；
ii)位于所述集流体至少一个表面上的阳极活性材料层；以及
iii)位于所述阳极活性材料层上的析锂抑制层，所述析锂抑制层包含以下析锂抑制材料中的至少一种：LiNi xCo yMn zFe wO 2、LiMPO 4、LiMO 2和Li 4Ti 5O 12，其中0≤x≤1，0≤y≤1，0≤z≤1，0≤w≤1，且x+y+z+w＝1，M选自Fe、Co、Ni、Mn或其组合。
根据本申请的一个实施方式，w的数值可以在以下数值中将任意两个分别作为上限和下限而获得的数值范围：0、0.01、0.015、0.02、0.025、0.03、0.035、0.04、0.05、0.06、0.07、0.075、0.08、0.085、0.09、0.1、0.15、0.2、0.25、0.3、1/3、0.35、0.4、0.45、0.5、0.55、0.6、0.65、2/3、0.7、0.75、0.8、0.85、0.9、0.95、0.99、1；根据一个优选的实施方式，w的数值可以为0或1。x的数值可以在以下数值中任意两个分别作为上限和下限而获得的数值范围：0.01、0.015、0.02、0.025、0.03、0.035、0.04、0.05、0.06、0.07、0.075、0.08、0.085、0.09、0.1、0.15、0.2、0.25、0.3、1/3、0.35、0.4、0.45、0.5、0.55、0.6、0.65、 2/3、0.7、0.75、0.8、0.85、0.9、0.95、0.99。根据本申请的另一个实施方式，y的数值可以在以下数值中任意两个分别作为上限和下限而获得的数值范围：0.01、0.015、0.02、0.025、0.03、0.035、0.04、0.05、0.06、0.07、0.075、0.08、0.085、0.09、0.1、0.15、0.2、0.25、0.3、1/3、0.35、0.4、0.45、0.5、0.55、0.6、0.65、2/3、0.7、0.75、0.8、0.85、0.9、0.95、0.99。根据本申请的另一个实施方式，z的数值可以在以下数值中任意两个分别作为上限和下限而获得的数值范围：0.01、0.015、0.02、0.025、0.03、0.035、0.04、0.05、0.06、0.07、0.075、0.08、0.085、0.09、0.1、0.15、0.2、0.25、0.3、1/3、0.35、0.4、0.45、0.5、0.55、0.6、0.65、2/3、0.7、0.75、0.8、0.85、0.9、0.95、0.99。在以上的实施方式中，均满足x+y+z+w＝1的前提条件。需要特别强调的是，虽然上文中将上述数值并列地列出，但是并不意味着发明人承认在上述任意两个数值作为端点组成的金属元素含量数值范围内都可以得到相当或相近的性能，关于本申请最优选的析锂抑制材料组成，仅仅基于下文中的具体讨论以及具体实验数据来进行选择。
根据本申请的一个实施方式，所述析锂抑制层包含以下材料中的至少一种：LiNi 0.85Co 0.075Mn 0.075O 2、LiNi 0.8Co 0.1Mn 0.1O 2、LiNi 0.7Co 0.15Mn 0.15O 2、LiNi 0.6Co 0.2Mn 0.2O 2、LiNi 0.5Co 0.2Mn 0.3O 2、LiNi 1/3Co 1/3Mn 1/3O 2、LiCoO 2、LiNiO 2、LiMnO 2、LiFeO 2、LiFePO 4、LiCoPO 4、LiNiPO 4、LiMnPO 4、Li 4Ti 5O 12。根据本申请的另一个实施方式，所述LiNi xCo yMn zFe wO 2是层状结构的复合金属氧化物(对于w＝0，且x、y和z均不为零的情况)或尖晶石结构的复合金属氧化物(对于w＝1且x、y和z均为零的情况)，所述LiMPO 4是橄榄石结构的复合金属氧化物，所述Li 4Ti 5O 12是尖晶石结构的复合金属氧化物。
不希望局限于任何具体的理论，现有技术的阳极极片通常仅仅包括集流体和位于集流体表面上的阳极活性材料层，而不包括设置在阳极活性材料层上的析锂抑制层，所述阳极活性材料层中通常包含碳活性材料(例如石墨、中间相碳微球、软碳、硬碳等)、导电剂(乙炔黑、炉黑、VGCF、碳纳米管等)、胶粘剂和任选的其他添加剂等。现有技术的这种仅包括集流体和阳极活性材料层的阳极极片组装到锂离子电池中，经历充电过程中，电解质中的锂离子会嵌入到阳极活性材料层中，但是锂离子在阳极活性材料层的表面和内部的嵌入并不均衡，锂离子在阳极活性材料层表面的富集容易导致阳极极片表面析出锂枝晶，并进一步带来短路的风险。而在阳极活性材料层上进一步设置陶瓷类绝缘材料层的做法非但无法真正有效地消除 上述阳极活性材料层的表面和内部的锂离子嵌入不均衡的问题，甚至还会进一步导致锂离子电池电池极化增加、能量密度降低、循环寿命短、充放电电压平台不稳定等问题。所有的现有技术都没有记载过本申请的包含特别设计材料的析锂抑制层。本申请基于该析锂抑制层的设计克服了现有技术的问题。
申请人还特别希望强调一点，迄今为止，有一些研究可能涉及在锂离子电池的阴极/正极中使用本申请所述的用于析锂抑制层的材料作为阴极活性材料，但是在本申请之前，从来没有报道过将所述材料用于锂离子电池的阳极/负极、形成阳极活性材料层之上的析锂抑制层。实际上，由于阴极与阳极处所发生的电化学反应的差异，本领域普通技术人员的普遍共识是不应当将阴极活性材料用于阳极。
根据本申请的一个实施方式，所述析锂抑制层包含第一胶粘剂(也即析锂抑制层的胶粘剂)，例如所述第一胶粘剂选自以下的一种或多种：聚偏二氟乙烯(也称为聚偏氟乙烯)、聚四氟乙烯、聚三氟氯乙烯。
根据本申请的一个实施方式，所述析锂抑制层不含导电材料。根据本申请的另一个实施方式，所述析锂抑制层不含阳极活性材料(阳极活性材料层中所使用的阳极活性材料)。根据本申请的另一个实施方式，所述析锂抑制层既不含导电材料也不含阳极活性材料层中的阳极活性材料。在以上所述的实施方式中，所述析锂抑制层不含任意一种常规碳导电材料，例如乙炔黑、炉黑、VGCF、碳纳米管碳纤维、石墨烯、炭黑、科琴黑、Super P等，另外，所述析锂抑制层也不含电极常用的除了碳以外的任意其他导电材料。在以上所述的实施方式中，所述析锂抑制层不含任意一种常规阳极活性材料，例如石墨、硬碳、硅基材料、锡基材料等。根据本申请的另一个实施方式，所述析锂抑制层仅仅由以上所述的析锂抑制材料和第一胶粘剂组成，而不含其他的组分。通过选择以上组成，本申请的阳极极片能够实现更进一步优化的性能。不希望局限于任意特定的具体理论，发明人非常出乎意料地发现，假设析锂抑制层中包含任意常规的导电剂以及阳极活性材料中的任意一种或两种，则析锂抑制层的效果会大打折扣，有可能无法很理想地实现本文所述的抑制析锂以及改善锂离子电池性能的效果。
根据本申请的一个实施方式，以所述析锂抑制层的干重为基准计，所述析锂抑制层中析锂抑制材料的含量为50至99.9重量％，例如55至99重量％，或者为60至98.5重量％，或者为65至98重量％，或者为70至97.5 重量％，或者为80至97重量％，或者为90至97重量％，或者为95至97重量％。根据本申请的另一个实施方式，以所述析锂抑制层的干重为基准计，所述析锂抑制层中第一胶粘剂的含量为0.01至50重量％，例如0.02至45重量％，或者为0.05至40重量％，或者为0.1至35重量％，或者为0.5至30重量％，或者为0.75至20重量％，或者为1至15重量％，或者为1.25至12.5重量％，或者为1.5至10重量％，或者为2至7重量％，或者为3至6重量％。根据本发明的一些实施方式，当锂抑制材料的含量在上述范围内的时候，可以有效地抑制锂在阳极表面的析晶，同时析锂抑制层与下方的阳极活性材料层之间具有足够的粘结力。当锂抑制材料的含量低于上述范围的下限的时候，无法实现显著抑制锂在表面析晶的效果，而当锂抑制材料高于上述范围的上限的时候，会导致析锂抑制层粘结力不足，有较高的脱层的风险。
根据本申请的一个实施方式，所述析锂抑制层的厚度为1.8-20微米，优选为2.3-15微米。例如，所述析锂抑制层的厚度可以在通过以下任意两个端点组合起来得到的数值范围之内：1.8微米、1.9微米、2微米、2.1微米、2.2微米、2.3微米、2.5微米、2.6微米、2.8微米、3微米、3.2微米、3.5微米、3.8微米、4微米、4.2微米、4.3微米、4.5微米、4.8微米、5微米、5.5微米、6微米、6.5微米、7微米、7.5微米、8微米、8.5微米、9微米、9.5微米、10微米、10.5微米、11微米、11.5微米、12微米、12.5微米、13微米、13.5微米、14微米、14.5微米、15微米、15.5微米、16微米、16.5微米、17微米、17.5微米、18微米、18.5微米、19微米、19.5微米、20微米。
根据本发明的一些实施方式，当析锂抑制层的厚度在上述范围内的时候，可以有效地抑制锂在阳极表面的析晶，同时能够确保电解液对极片的充分润湿，当所述析锂抑制层的厚度小于上述数值范围的下限的时候，会导致无法有效地实现阳极表面处析锂的抑制效果；而当所述析锂抑制层的厚度大于上述数值范围的上限的时候，会导致电解液不能充分润湿极片。
根据本申请的另一个实施方式，所述阳极活性材料层的厚度为30-340微米，优选为55-260微米。例如，所述阳极活性材料层的厚度可以在通过以下任意两个端点组合起来得到的数值范围之内：30微米、35微米、40微米、45微米、50微米、55微米、60微米、65微米、70微米、75微米、80微米、85微米、90微米、95微米、100微米、105微米、110微米、115微米、 120微米、125微米、130微米、135微米、140微米、145微米、150微米、155微米、160微米、165微米、170微米、175微米、180微米、185微米、190微米、195微米、200微米、205微米、210微米、215微米、220微米、225微米、230微米、235微米、240微米、245微米、250微米、255微米、260微米、270微米、275微米、280微米、285微米、290微米、295微米、300微米、305微米、310微米、315微米、320微米、325微米、330微米、335微米、340微米。
根据本发明的一些实施方式，当所述阳极活性材料层的厚度在上述范围内的时候，可以确保电池具有足够高的能量密度，同时能够确保电解液对极片的充分润湿，当所述阳极活性材料层的厚度小于上述数值范围的下限的时候，会导致电池能量密度过低；而当所述阳极活性材料层的厚度大于上述数值范围的上限的时候，电解液不能充分润湿极片，导致能量密度也不能充分提高。
根据本发明的一些实施方式，所述析锂抑制层的厚度为2.3-15微米，并且所述阳极活性材料层的厚度为55-260微米；在所述析锂抑制层和阳极活性材料层的厚度满足上述限定的情况下，所述析锂抑制层的厚度与所述阳极活性材料层的厚度之比可为0.018-0.2，优选为0.023-0.15，例如可以为以下任意两个数值相组合得到的数值范围之内：0.018、0.023、0.033、0.06、0.10、0.11、0.15、0.2。在这些实施方式中，当所述析锂抑制层和阳极活性材料层的厚度均在上述范围内、且所述析锂抑制层的厚度与所述阳极活性材料层的厚度之比也在上述范围之内的时候，可以使得析锂抑制效果最优化，由此确保电池实现优异的首次库伦效率、循环性能和较高的能量密度。
根据本申请的一个实施方式，所述阳极活性材料层包含：活性材料，其选自以下的一种或多种：石墨(例如天然石墨或人造石墨)、硬碳、硅基材料(例如单质硅、氧化亚硅、硅碳复合物)、锡基材料(例如单质锡、锡氧化合物、锡合金)；第二胶粘剂，其选自以下的一种或多种：丁苯橡胶(SBR)、水溶性不饱和树脂SR-1B、海藻酸钠(SA)、聚氨酯、聚丙烯酸(PAA)、聚甲基丙烯酸(PMAA)、聚丙烯酸钠(PAAS)、聚羧甲基纤维素钠、丙烯酰胺(PAM)、聚乙烯醇(PVA)、和羧甲基壳聚糖(CMCS)；以及导电剂，其选自以下的一种或多种：碳纳米管、碳纤维、石墨烯、炭黑、科琴黑、Super P。
根据本申请的一个实施方式，所述析锂抑制层与阳极活性材料层的电势差为1-4伏，例如2-2.3伏。例如，所述析锂抑制层的电位比阳极活性材料层的电位高1-4伏，优选高2-2.3伏。根据本发明的一些实施方式，当所述析锂抑制层与阳极活性材料层的电势差在上述范围内的时候，可以确保电池具有足够高的能量密度，同时能够确保电池的正常工作，当所述析锂抑制层与阳极活性材料层的电势差小于上述数值范围的下限的时候，会导致无法有效地实现抑制阳极极片表面析锂的效果；而当所述析锂抑制层与阳极活性材料层的电势差大于上述数值范围的上限的时候，阳极极片的总体正常工作会受到不利影响。
根据本申请的一个实施方式，所述集流体为金属箔、金属合金箔、具有金属涂层的聚合物片材或者具有金属合金涂层的聚合物片材；其中所述金属箔和金属涂层中的金属选自铜、银、铁、钛、镍；所述金属合金箔和金属合金涂层中的金属合金选自铜合金、镍合金、钛合金、银合金、铁合金；所述聚合物片材选自聚丙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚苯乙烯、聚乙烯及其混合物和共聚物。
根据本申请的一个实施方式，所述负极可以通过以下方式制备：使用包含阳极活性材料、导电剂、胶粘剂(即用于阳极活性层的胶粘剂或第二胶粘剂)以及其他可选助剂与分散剂(例如N-甲基吡咯烷酮(NMP)或去离子水)混合而形成浆料，将该浆料涂布在集流体上，随后进行干燥以形成阳极活性材料层，然后可以将包含析锂抑制材料、胶粘剂(即用于析锂抑制层的胶粘剂或第一胶粘剂)和分散剂的析锂抑制层浆料涂布在阳极活性材料层，随后进行干燥以形成析锂抑制层。所述阳极活性材料层中可选地包括的其他助剂的例子可以是增稠剂(如羧甲基纤维素钠CMC-Na)、PTC热敏电阻材料等。
另外，在本申请的锂离子二次电池中，阳极/负极极片并不排除其他附加功能层。例如在一些实施方式中，阳极/负极极片还可包括设置在负极集流体和阳极活性材料层之间的导电底涂层(例如由导电剂和粘结剂组成)。
图1显示了根据本发明一个实施方式形成的阳极/负极极片，其中在中央的集流体的两个表面上分别形成了阳极活性材料层和析锂抑制层。根据本发明的另一个实施方式，可以仅在集流体的一个表面上形成阳极活性材料层和析锂抑制层。根据本发明的一个实施方式，所述析锂抑制层对所述阳极活性材料层的整个外表面(阳极活性材料层的与集流体相背的表面)进行完全覆盖。
在本申请的一些实施方式中，提供了一种锂离子二次电池，其包括正极极片、负极极片、隔离膜、电解质等。在电池充放电过程中，锂离子作为活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。其中使用的负极极片(阳极极片)为本申请的负极/阳极极片。
在锂离子二次电池中，正极极片包括正极集流体以及设置在正极集流体至少一个表面且包括正极活性材料的正极膜层。例如，正极集流体具有在自身厚度方向相背的两个表面，正极膜层设置于正极集流体的两个相背表面中的任意一者或两者上。
在锂离子二次电池中，所述正极集流体可以是金属箔片或复合集流体，例如所述金属箔片可以是铝箔，而所述复合集流体可包括高分子材料基层和形成于该高分子材料基层至少一个表面上的金属层。所述复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯PP、聚对苯二甲酸乙二醇酯PET、聚对苯二甲酸丁二醇酯PBT、聚苯乙烯PS、聚乙烯PE及其共聚物等的基材)上而形成。
在锂离子二次电池中，所述正极活性材料可采用本领域公知的用于锂离子二次电池的正极活性材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，正极膜层还可选地包括胶粘剂。可用于正极膜层的胶粘剂的非限制性例子可以包括以下的一种或多种：聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂。
在一些实施方式中，正极膜层还可任选地包含导电剂。用于正极膜层的导电剂的例子可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或几种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、胶粘剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成均匀的正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
电解质在正极/阴极极片和负极/阳极极片之间起到传导离子的作用。电解质可以选自固态电解质及液态电解质(即电解液)中的至少一种。
根据本申请的一些实施方式，由于本申请中的阳极极片具有专门设计的集流体+阳极活性材料层+析锂抑制层的结构，并且对析锂抑制层中的材料进行了特别设计，使得本发明锂离子二次电池中阳极和阴极的容量比不会发生显著的提高，例如阳极和阴极的容量比(CB值)为1.07至1.01，或者为1.07至1.03，或者在以下任意两个数值组合起来得到的数值范围之内：1.07、1.06、1.05、1.04、1.03、1.02、1.01。以上所述的CB值表示电池中负极/阳极容量和正极/阴极容量的比值，可以按照下式计算：
CB值＝(阳极面密度×阳极活性材料比例×阳极活性材料放电比容量)/(阴极面密度×阴极活性材料比例×阴极活性材料放电比容量)
因此，在本发明中，每个电池的具体CB值是基于具体选择的正极和负极上施加的活性材料种类和用量(例如基于极片厚度、所含活性材料比例等)而准确确定的。
根据本发明的一些实施方式，当阳极和阴极的容量比在上述范围之内的时候，能够实现适当的电池能量密度，并且可以有效地抑制阳极极片表面的析锂，当本发明锂离子二次电池中阳极和阴极的容量比高于上述数值范围的上限的时候，会导致电池的能量密度显著降低；而当本发明锂离子二次电池中阳极和阴极的容量比低于上述数值范围的下限的时候，阳极极片的表面会很容易发生析锂。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。在一些实施方式中，电解质盐可选自六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO 2F 2)、二氟二草酸磷酸锂(LiDFOP)及四氟草酸磷酸锂(LiTFOP)中的一种或几种。
在一些实施方式中，溶剂可选自以下的一种或多种：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)及二乙砜(ESE)。
在一些实施方式中，以所述电解液的总重量为基准计，所述溶剂的含量为60-99重量％，例如65-95重量％，或者70-90重量％，或者75-89重量％，或者80-85重量％。在一些实施方式中，以所述电解液的总重量为基准计，所述电解质的含量为1-40重量％，例如5-35重量％，或者10-30重量％，或者11-25重量％，或者15-20重量％。
在一些实施方式中，所述电解液中还可任选地包含添加剂。例如添加剂可以包括以下的一种或多种：负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温性能的添加剂等。
在一些实施方式中，所述锂离子二次电池还包括隔离膜，隔离膜将锂离子二次电池的阳极极片与阴极极片隔开，对体系内不同种类、尺寸和电荷的物质提供选择性透过或阻隔，例如隔离膜可以对电子绝缘，将锂离子二次电池的正负极活性物质物理隔离，防止内部发生短路并形成一定方向的电场，同时使得电池中的离子能够穿过隔离膜在正负极之间移动。
在一些实施方式中，用来制备隔离膜的材料可包括玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的一种或几种。隔离膜可以是单层薄膜，也可以是多层复合薄膜。隔离膜为多层复合薄膜时，各层的材料可以相同或不同。
在一些实施方式中，上述阳极极片、阴极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，锂离子电池可包括外包装，该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，锂离子电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。
在一些实施方式中，所述锂离子电池的外包装可以是软包，例如袋式软包。软包的材质可以是塑料，如聚丙烯(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。
锂离子电池的形状可以是圆柱形、方形或其他任意的形状。图5是作为一个示例的方形结构的锂离子电池5。图6显示了图5的锂离子电池5的分解图，所述外包装可包括壳体51和盖板53，壳体51可包括底板和连接于底板上的侧板，所述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卷绕工艺或叠片工艺形成电极组件52，该电极组件封装于所述容纳腔中，所述电解液浸润于电极组件52中。锂离子电池5所含电极组件52的数量可以为一个或多个。
在一些实施方式中，可以将若干个锂离子电池组装在一起以构成电池模组，电池模组中包含两个或更多个锂离子电池，具体数量取决于电池模组的应用和单个电池模组的参数。
图7是作为一个示例的电池模组4。参照图7，在电池模组4中，多个锂离子电池5可以是沿电池模组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锂离子电池5进行固定。
可选地，电池模组4还可以包括具有容纳空间的外壳，多个锂离子电池5容纳于该容纳空间。
在一些实施方式中，可以将两个或更多个上述电池模组组装成电池包，电池包所含电池模组的数量取决于电池包的应用和单个电池模组的参数。电池包可以包括电池箱和设置于电池箱中的多个电池模组，该电池箱包括上箱体和下箱体，上箱体能够盖在下箱体上并与之良好匹配，形成用于容纳电池模组的封闭空间。两个或更多个电池模组可以按照所需的方式排布于该电池箱中。
图8和图9是作为一个示例的电池包1。参照图8和图9，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组4。电池箱包括上箱体2和下箱体3，上箱体2用于盖设下箱体3，并形成用于容纳电池模组4的封闭空间。多个电池模组4可以按照任意的方式排布于电池箱中。
本申请还提供一种用电装置，所述用电装置包括上述的锂离子电池、电池模组、或电池包中的至少一种。所述锂离子电池、电池模组、或电池包可以用 作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置包括但不限于移动数字用电装置(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。
图10是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对高功率和高能量密度的需求，可以采用电池包或电池模组。
作为另一个示例的用电装置可以是手机、平板电脑、笔记本电脑等。该用电装置通常要求轻薄化，可以采用锂离子电池作为电源。
在下文中，基于具体的实施例表征了按照本申请实施方式制造的阳极极片对锂离子二次电池性能的影响，但是需要特别指出的是，本申请的保护范围由权利要求书限定，而不仅限于以上的具体实施方式。
实施例
除非另外说明，本申请使用的原料均为分析纯，水均为去离子水。
在本发明的实施例中，使用以下析锂抑制材料进行阳极极片析锂抑制层的合成：
析锂抑制材料 供应商
LiFePO 4 厦门钨业股份有限公司
LiNi 0.5Co 0.2Mn 0.3O 2 湖南邦普循环科技有限公司
LiNi 1/3Co 1/3Mn 1/3O 2 湖南邦普循环科技有限公司公司
LiNi 0.8Co 0.1Mn 0.1O 2 湖南邦普循环科技有限公司公司
LiCoO 2 厦门钨业股份有限公司
Li 2Mn 2O 4(即LiMnO 2) 厦门钨业股份有限公司
Li 4Ti 5O 12 深圳贝特瑞能源材料股份有限公司
实施例1
在该实施例中，合成了包含LiFePO 4的析锂抑制层的阳极极片，并对包括该阳极极片的锂离子电池进行表征。
负极/阳极的制造：将石墨、胶粘剂丁苯橡胶(SBR)、增稠剂羧甲基纤 维素钠(CMC-Na)以及导电剂炭黑以96.2∶1.8∶1.2∶0.8的重量比在去离子水中充分搅拌混合，使其形成固体含量为30重量％的均匀的浆料；将该浆料涂覆于负极集流体铜箔的表面上，将其转移入烘箱中，在150℃的温度下烘干60分钟，形成厚度为150微米的干涂层(即阳极活性材料层)。然后将其从烘箱中取出，将LiFePO 4和作为胶粘剂的聚偏氟乙烯以97∶3的重量比在去离子水中充分搅拌混合，使其形成固体含量为30重量％的均匀浆料，将该浆料涂覆于此前形成的阳极活性材料层上，将其转移入烘箱中，在150℃的温度下烘干60分钟，形成厚度为15微米的干涂层(即析锂抑制层)，在本实施例中，得到的析锂抑制层厚度与阳极活性材料层厚度之比等于0.1。使用辊压机以60吨的压力进行冷压，得到阳极极片。图2b显示了该阳极极片表面的光学照片。
正极/阴极的制造：将锂镍钴锰三元活性物质LiNi 0.5Co 0.2Mn 0.3O 2(NCM523)、导电剂炭黑、粘结剂PVDF按重量比94∶3∶3在适量的N-甲基吡咯烷酮(NMP)中充分搅拌混合均匀，使其形成固体含量为30重量％的均匀正极浆料；使用转移涂布法在厚度为12μm的Al箔的一侧表面上形成厚度为250μm的湿涂层，然后转移入烘箱中，在150℃的温度下烘干60分钟，使用辊压机以60吨的压力进行冷压，得到正极极片，其中干涂层厚度为130μm。在本实施例中，阳极极片与阴极极片的CB值为1.07。
选用厚度为16μm的PE薄膜作为隔膜。
将碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)按照体积比1∶1∶1混合，接着将充分干燥的锂盐LiPF 6均匀溶解在上述混合溶剂中以得到电解液，其中LiPF 6的浓度为1mol/L。
将上述正极极片、隔离膜、负极极片按顺序叠置并卷绕，形成尺寸为5.1cm×4.4cm×0.5cm的卷绕层叠结构。将该卷绕层叠结构置于铝质外壳中，向其中注入150克电解液并封装，在静置、化成、老化之后得到锂离子二次电池。制备的电芯首先静置6小时，然后安装在购自武汉蓝电的充放电测试仪中，在45℃下采用以下条件进行测量：首先在0.1C下充电至3.4V，静置15分钟，然后在0.33C下充电至3.8V，获得的结果如图3中的曲线b所示。
对比例1
在该对比例1中基本重复了实施例1的步骤来制造阳极极片和锂离子电池，区别仅在于：形成阳极活性材料层之后，没有在阳极活性材料层上进一步设置析锂抑制层。图2a显示了该阳极极片表面的光学照片。在本实施例中，阳极极片与阴极极片的CB值为1.07。按照与实施例1相同的方式在室温下测试其充电曲线，结果如图3中的曲线a所示。
通过观察图2a和图2b可以看到：实施例1通过上述步骤制得的阳极极片最外部的析锂抑制层具有非常均匀的表面，比较例1通过上述步骤制得的阳极极片最外部的阳极活性材料层也具有非常均匀的表面。
图3中的a和b两条曲线电压值相减即可得到图4所示的电压差曲线，该电压差曲线体现了实施例1与比较例1阳极极片表现出的电压差，具体来说，从图4的曲线可以观察到：在阳极活性层(包含石墨作为阳极活性材料)的表面涂覆包含LiFePO 4的析锂抑制层后，不同SOC下表面阳极电位提升200～620mV。
此处所示的电位提高反应的是析锂抑制层与阳极活性材料层总体作为阳极的实施例1相对于阳极中不含析锂抑制层的对比例1的阳极总体电势变化，实施例1中析锂抑制层和阳极活性材料层的电势差在本申请限定的1-4伏范围之内，大约为3.2V。
实施例2
使用实施例1制备得到的阳极极片和阴极极片(CB值为1.07)，按照与实施例1相同的方式制造电池，区别仅在于，另外在阳极表面设置一根直径200微米的铜丝，改铜丝引出电极并焊接镍片，作为第三个电极(参比电极)，由此得到一个三电极电池，在室温下通过以下方式验证不同倍率下的析锂窗口：
(1)铜丝表面镀锂，将充放电测试仪的正极连接电池阴极、充放电测试仪的负极连接铜丝，在20微安电流下充电两个小时，使阴极中的锂离子沉积在铜丝上。随后将充放电测试仪的正极连接电池阳极、负极连接铜丝， 在20微安电流下充电两个小时，使阳极中的锂离子沉积在铜丝上。
(2)不同倍率充放电，在室温下选择不同的倍率(0.33C、1C、3C和5C)进行充电，同时监控第三个电极(铜丝)电位和阳极电位，使两者的电势差(电位)为0伏特截止，监测不同倍率下的SOC(荷电状态，该SOC＝充电容量/电芯总容量)，用以表征电池中阳极极片表面上的析锂窗口。测得的结果汇总列于下表1中。
对比例2
在该对比例2中基本重复了实施例2的步骤来制造三电极电池，区别仅在于，使用了对比例1的阳极极片，在阳极活性材料层上没有进一步设置析锂抑制层。按照与实施例2相同的方式在室温下监测不同倍率下的SOC(荷电状态)，用以表征电池中阳极极片表面上的析锂窗口，其结果汇总示于表1，该表1所示的是阳极电位为零时对应不同倍率电池的SOC。
表1：实施例2和对比例2的析锂窗口表征结果
Figure PCTCN2022077075-appb-000001
从上表1的结果可以看到，室温下实施例2所制备的电池在测试的任意倍率下均未表现出SOC的下降，表明这些倍率下均未发生析锂；而对比例2所制备的电池在1C倍率以上均发生SOC下降，表示发生了析锂，且随着倍率增大，SOC下降程度随之增大，表明发生了更严重的析锂现象。
实施例3
重复实施例2的步骤，以构造三电极电池并在室温下测量不同倍率(0.33C，1C，3C，5C)下的SOC(每次实验在相同条件下在三个电芯上进行，测试结果取三个电芯数据的平均值)，以考察其析锂窗口，该实施例3与实施例1的区别还在于，通过略微调整阴极活性材料的用量，使得CB值分别改变为1.01、1.03和1.05。按照与实施例2相同的方式在室温下 验证不同倍率下的SOC，用以表征电池中阳极极片表面上的析锂窗口，其结果示于表2。
对比例3
重复对比例2的步骤，以构造三电极电池并按照对比例2所述的测试技术在室温下测量不同倍率(0.33C，1C，3C，5C)下的SOC(每次实验在相同条件下在三个电芯上进行，测试结果取三个电芯数据的平均值)，以考察其析锂窗口，该对比例3与对比例2的区别还在于，通过略微调整阴极活性材料的用量，使得实验中CB值分别改变为1.01、1.03和1.05。在室温下验证不同倍率下的SOC，用以表征电池中阳极极片表面上的析锂窗口，其结果示于表2，表2所示的实验结果是阳极电位为零时具有不同CB值的锂离子电池的SOC。
表2：实施例3和对比例3的析锂窗口表征结果
Figure PCTCN2022077075-appb-000002
从表2所示的实验结果可以看到，对于各种不同的CB值，实施例3的锂离子电池的SOC变化程度均显著小于对比例3，这表明实施例3在任意CB值条件下均有效地抑制了析锂。
实施例4
在该实施例中，重复实施例1的步骤合成了锂离子电池(CB值为1.07)。在室温和1C倍率条件下进行充电-放电循环，采用的充放电电压范围为2.8V～4.35V，充电电流为1C，具体流程如下：(1)在1C电流下充电至4.35V并测定此过程的充电容量，作为首次充电容量；(2)静置10分钟；(3)在1C 电流下放电至2.8V并测定此过程的放电容量，作为首次放电容量，基于上述放电容量和充电容量计算电池的首次库伦效率(％)＝(首次放电容量/首次充电容量)×100％；(4)静置10分钟；(5)重复以上所述的步骤1至步骤4，直到容量衰减至80％。测试循环性能并计算电池循环500圈后的能量密度，并且测量电池容量衰减至初始容量的80％所需的循环次数。其结果示于表3。
对比例4
在该对比例中，重复对比例1的步骤合成了锂离子电池(CB值为1.07)。在室温1C倍率下进行充电-放电循环测试并计算电池的首次库伦效率、循环500圈后的能量密度，并且测量电池容量衰减至初始容量的80％所需的循环次数。其结果示于表3。
表3.实施例4和对比例4的包括不同阳极极片的锂离子电池的性能表征
Figure PCTCN2022077075-appb-000003
从表3的实验结果可以看到，实施例4的电池具有更高的首次库伦效率以及更佳的循环性能。由于实施例4和对比例4的区别仅在于阳极表面上是否设置了析锂抑制层，由此表明本发明设置析锂抑制层的做法能够显著地改善上述性能。
实施例5
在该实施例5中，重复实施例1的步骤以制得锂离子电池。区别仅在于通过调整阳极活性材料层的涂覆量以将阳极活性材料层的厚度改变为20、30、55、100、260、340和400微米，并且在阳极活性材料层上形成的析锂抑制层厚度为6微米，在该实施例中，析锂抑制层的厚度与阳极活性材料层的厚度之比分别等于0.3、0.2、0.11、0.06、0.023、0.018和0.015。与此同时，阴极活性材料层的涂覆厚度成比例地改变，以将电池的CB值保持 在1.07。在室温1C倍率下进行充电-放电循环测试，并计算电池的首次库伦效率、循环500圈后的能量密度，并且测量电池容量衰减至初始容量的80％所需的循环次数。其结果示于表4。
对比例5
在该对比例5中，重复比较例1的步骤以制得锂离子电池。区别仅在于通过调整阳极活性材料层的涂覆量以将阳极活性材料层的厚度改变为30、55、100、260和340微米。与此同时，阴极/正极活性材料层的涂覆厚度成比例地改变，以将电池的CB值保持在1.07。在室温1C倍率下进行充电-放电循环测试，并计算电池的首次库伦效率、循环500圈后的能量密度，并且测量电池容量衰减至初始容量的80％所需的循环次数。其结果示于表4。
表4：实施例5和对比例5的具有不同阳极活性材料层厚度的电池的性能表征
Figure PCTCN2022077075-appb-000004
从以上表4所示的实验结果可以看到，当实施例5的阳极活性材料层厚度为30-340微米的范围内且析锂抑制层厚度与阳极活性材料层厚度之比在0.018至0.2的范围之内时，实施例5的电池在首次库伦效率、容量衰减性质方面均显著优于对比例5的相应性能。另外，在实施例5中，当阳极 活性材料层的厚度在55-260微米范围内的时候可以实现电池循环性能的进一步改善。更进一步来说，阳极活性材料层的厚度在100微米的条件下可以实现特别优化的电池循环性能。另外，发现当实施例5中电池的阳极活性材料厚度在30-340微米的范围以外且析锂抑制层厚度与阳极活性材料层厚度之比在0.018至0.2的范围以外时，实施例5制得的锂离子电池仍然具有显著优于对比例5的首次库伦效率以及电池容量抗衰减性(电池容量衰减至初始容量的80％所需的循环次数)，但是并不能像具有上文所述的优选阳极活性材料层厚度和析锂抑制层/阳极活性材料层厚度比的电池那样实现优异的循环500圈后的能量密度。
实施例6
在该实施例6中，重复实施例1的步骤以制得锂离子电池。区别仅在于通过调整阳极活性材料层的涂覆量以将阳极活性材料层的厚度保持在100微米，并且通过控制在阳极活性材料层上施涂的析锂抑制层浆料的量，将形成的析锂抑制层的厚度调节为30、20、11、6、2.3、1.8和1.5微米(析锂抑制层的厚度比阳极活性材料层的厚度分别等于0.3、0.2、0.11、0.06、0.023、0.018、0.015)。阴极/正极活性材料层的涂覆厚度与阳极活性材料厚度成比例地进行选择，以将电池的CB值保持在1.07。在室温1C倍率下进行充电-放电循环测试，并计算电池首次库伦效率、循环500圈后的能量密度，并且测量电池容量衰减至初始容量的80％所需的循环次数。其结果示于表5。
表5：实施例6的具有不同析锂抑制层厚度的电池的性能表征
Figure PCTCN2022077075-appb-000005
Figure PCTCN2022077075-appb-000006
从以上表5所示的实验结果可以看到，实施例6中析锂抑制层厚度的变化也会对电池的循环性能带来影响。当析锂抑制层的厚度在1.8-20微米、且析锂抑制层厚度与阳极活性材料层厚度之比在0.018至0.2的范围之内时，锂离子电池在首次库伦效率、容量衰减性质方面都比较令人满意，当析锂抑制层的厚度在2.3-15微米、且析锂抑制层厚度与阳极活性材料层厚度之比在0.023至0.15的范围之内时，可以实现电池循环性能的进一步改善。更进一步来说，析锂抑制层的厚度在6微米的条件下可以实现特别优化的首次库伦效率和循环性能。另外从以上的实验结果还可以观察到，当实施例6中电池的析锂抑制层厚度在1.8-20微米的范围以外且析锂抑制层厚度与阳极活性材料层厚度之比在0.018至0.2的范围以外时，锂离子电池在首次库伦效率以及电池容量抗衰减性(电池容量衰减至初始容量的80％所需的循环次数)方面仍然可以得到较为优良的结果(例如相较于上表4所示的未使用析锂抑制层厚度的对比例电池)，证明此厚度的析锂抑制层仍然能够一定程度上发挥析锂抑制效果，但是并不能像具有上文所述的优选析锂抑制层厚度和析锂抑制层/阳极活性材料层厚度比的电池那样实现优异的循环500圈后的能量密度。
实施例7
在该实施例7中，按照以下步骤进行负极/阳极的制造：将石墨、胶粘剂聚氨酯、增稠剂羧甲基纤维素钠(CMC-Na)以及导电剂碳纤维以96.5∶1.35∶1.35∶0.8的重量比去离子水中充分搅拌混合，使其形成固体含量为30重量％的均匀的浆料；将该浆料涂覆于负极集流体铜箔的表面上，将其转移入烘箱中，在150℃的温度下烘干60分钟，形成厚度为120微米的干涂层(即阳极活性材料层)。然后将其从烘箱中取出，分别将Li 4Ti 5O 12、LiFePO 4、LiCoO 2、Li 2Mn 2O 4、LiNi 0.5Co 0.2Mn 0.3O 2、LiNi 1/3Co 1/3Mn 1/3O 2、LiNi 0.8Co 0.1Mn 0.1O 2和作为胶粘剂的聚四氟乙烯以97.1∶2.9的重量比在去离子水中充分搅拌混合，使其形成固体含量为30重量％的均匀浆料，将该浆料涂覆于此前形成的阳极活性材料层上，将其转移入烘箱中，在150℃的温 度下烘干60分钟，形成厚度为4微米的干涂层(即析锂抑制层)，该实施例采用的析锂抑制层的厚度与阳极活性材料层的厚度之比等于0.033。使用辊压机以60吨的压力进行冷压，得到阳极极片。
使用以上所述的阳极极片，按照与实施例1相同的步骤制造锂离子电池，其中对阴极极片中阴极活性材料的厚度进行调整，以将所有电池中的CB值保持在1.07。在室温1C倍率下进行充电-放电循环测试，并计算电池首次库伦效率、循环500圈后的能量密度，并且测量电池容量衰减至初始容量的80％所需的循环次数。其结果示于表6。
对比例6
在该对比例6中，重复比较例1的步骤以制得锂离子电池。区别仅在于通过调整阳极活性材料层的涂覆量以将阳极活性材料层的厚度改变为120微米。与此同时，阴极/正极活性材料层的涂覆厚度成比例地改变，以将电池的CB值保持在1.07。在室温1C倍率下进行充电-放电循环测试，并计算电池的首次库伦效率、循环500圈后的能量密度，并且测量电池容量衰减至初始容量的80％所需的循环次数。其结果示于表6。
对比例7
按照与实施例7相同的方式制造锂离子电池，区别仅在于制造析锂抑制层所使用的固体原料是Li 4Ti 5O 12、炭黑和聚四氟乙烯(97.1∶1∶1.9)的混合物。电池中的CB值保持在1.07。在室温1C倍率下进行充电-放电循环测试，并计算电池的首次库伦效率、循环500圈后的能量密度，并且测量电池容量衰减至初始容量的80％所需的循环次数。其结果示于表6。
对比例8
按照与实施例8相同的方式制造锂离子电池，区别仅在于制造析锂抑制层所使用的固体原料是LiFePO 4、炭黑和聚四氟乙烯(97.1∶1∶1.9)的混合物。电池中的CB值保持在1.07。在室温1C倍率下进行充电-放电循环测试，并计算电池的首次库伦效率、循环500圈后的能量密度，并且测量电 池容量衰减至初始容量的80％所需的循环次数。其结果示于表6。
表6：具有包含不同材料的析锂抑制层的锂离子电池的性能表征
Figure PCTCN2022077075-appb-000007
另外，综合考虑以上表3-表6所示的实验结果，发现当析锂抑制层的厚度为1.8-20微米，优选2.3-15微米，更优选4-15微米，阳极活性材料层的厚度为30-340微米，优选55-260微米，更优选100-150微米，且析锂抑制层的厚度与阳极活性材料层的厚度为0.018-0.20，优选0.023-0.11，更优选0.033-0.10的情况下，可以实现极为优异的首次库伦效率和循环性能。
实施例8
重复实施例7的步骤，使用多种不同的析锂抑制层析锂抑制材料制备阳极极片和锂离子电池。在室温下测试产气性能(通过1C满充的电芯的注液孔与气压流量计连接进行气压检测)和安全性能(将直径为1mm不锈钢针以0.1mm/s的速度从大面铝壳插入电芯至2mm和5mm)。其结果示于表7。
对比例9
重复对比例6的步骤以制造锂离子电池。在室温下测试产气性能(通过1C满充的电芯的注液孔与气压流量计连接进行气压检测)和安全性能(将直径为1mm不锈钢针按照0.1mm/s的速度从大面铝壳插入电芯至2mm和5mm)。其结果示于表7。
对比例10
重复对比例7的步骤以制造锂离子电池。在室温下测试产气性能(通过1C满充的电芯的注液孔与气压流量计连接进行气压检测)和安全性能(将直径为1mm不锈钢针按照0.1mm/s的速度从大面铝壳插入电芯至2mm和5mm)。其结果示于表7。
对比例11
重复对比例8的步骤以制造锂离子电池。在室温下测试产气性能(通过1C满充的电芯的注液孔与气压流量计连接进行气压检测)和安全性能(将直径为1mm不锈钢针按照0.1mm/s的速度从大面铝壳插入电芯至2mm和5mm)。其结果示于表7。
表7：锂离子电池的针刺结果和产气特性
Figure PCTCN2022077075-appb-000008
本申请所有实施例中选用的析锂抑制层与阳极活性材料层之间的电势差都在1-4伏的范围之内。

Claims (14)

  1. 一种用于锂离子电池的阳极极片，该阳极极片包括：
    i)集流体；
    ii)位于所述集流体至少一个表面上的阳极活性材料层；以及
    iii)位于所述阳极活性材料层上的析锂抑制层，所述析锂抑制层包含以下析锂抑制材料中的至少一种：LiNi xCo yMn zFe wO 2、LiMPO 4、Li 4Ti 5O 12，其中0≤x≤1，0≤y≤1，0≤z≤1，0≤w≤1，且x+y+z+w＝1，M选自Fe、Co、Ni、Mn或其组合。
  2. 根据权利要求1所述的阳极极片，其特征在于，所述析锂抑制层包含以下析锂抑制材料中的至少一种：LiNi 0.85Co 0.075Mn 0.075O 2、LiNi 0.8Co 0.1Mn 0.1O 2、LiNi 0.7Co 0.15Mn 0.15O 2、LiNi 0.6Co 0.2Mn 0.2O 2、LiNi 0.5Co 0.2Mn 0.3O 2、LiNi 1/3Co 1/3Mn 1/3O 2、LiCoO 2、LiNiO 2、LiMnO 2、LiFeO 2、LiFePO 4、LiCoPO 4、LiNiPO 4、LiMnPO 4、Li 4Ti 5O 12。
  3. 根据权利要求1所述的阳极极片，其特征在于，所述析锂抑制层不含导电材料。
  4. 根据权利要求3所述的阳极极片，其特征在于，所述析锂抑制层不含碳基导电材料。
  5. 根据权利要求1所述的阳极极片，其特征在于，所述析锂抑制层由所述析锂抑制材料和一种或多种胶粘剂组成。
  6. 根据权利要求1所述的阳极极片，其特征在于，所述析锂抑制层的厚度为1.8-20微米；所述阳极活性材料层的厚度为30-340微米，所述析锂抑制层的厚度为所述阳极活性材料层的厚度的0.018倍-0.2倍。
  7. 根据权利要求1所述的阳极极片，其特征在于，所述析锂抑制层的厚度为2.3-15微米；所述阳极活性材料层的厚度为55-260微米，所述析锂抑制层的厚度为所述阳极活性材料层的厚度的0.023倍-0.11倍。
  8. 根据权利要求1所述的阳极极片，其特征在于，所述析锂抑制层与所述阳极活性材料层的电势差为1-4伏。
  9. 一种锂离子电池，其包括阴极极片、电解质和根据权利要求1-8中任一项所述的阳极极片。
  10. 根据权利要求9所述的锂离子电池，所述阳极极片和所述阴极极片的容量比为1.07至1.01。
  11. 一种抑制锂离子电池中阳极极片表面析锂的方法，该方法包括：
    提供阳极极片，所述阳极极片包括集流体和位于所述集流体至少一个表面上的阳极活性材料层；
    在所述阳极活性材料层的表面上设置析锂抑制层，所述析锂抑制层包含以下材料中的至少一种：LiNi xCo yMn zFe wO 2、LiMPO 4、Li 2M 2O 4和Li 4Ti 5O 12，其中0≤x≤1，0≤y≤1，0≤z≤1，0≤w≤1，且x+y+z+w＝1，M选自Fe、Co、Ni、Mn或其组合。
  12. 一种电池模组，包括根据权利要求9或10所述的锂离子电池。
  13. 一种电池包，包括根据权利要求12所述的电池模组。
  14. 一种用电装置，其包括根据权利要求9或10所述的锂离子电池、根据权利要求12所述的电池模组以及根据权利要求13所述的电池包中的至少一种。
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