WO2025035488A1 - 一种正极极片及其制备方法与应用 - Google Patents

一种正极极片及其制备方法与应用 Download PDF

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Publication number
WO2025035488A1
WO2025035488A1 PCT/CN2023/114585 CN2023114585W WO2025035488A1 WO 2025035488 A1 WO2025035488 A1 WO 2025035488A1 CN 2023114585 W CN2023114585 W CN 2023114585W WO 2025035488 A1 WO2025035488 A1 WO 2025035488A1
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positive electrode
lithium
layer
active material
solid electrolyte
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French (fr)
Inventor
金周
黄学杰
闫勇
詹元杰
马晓威
胡保平
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Institute of Physics of CAS
Songshan Lake Materials Laboratory
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Institute of Physics of CAS
Songshan Lake Materials Laboratory
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Publication of WO2025035488A1 publication Critical patent/WO2025035488A1/zh
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—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
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to the technical field of lithium battery energy storage, and in particular to a positive electrode plate and a preparation method and application thereof.
  • a solid electrolyte interface (SEI) film is formed at the negative electrode interface of a lithium battery energy storage device, which causes a portion of the active lithium to be deactivated and causes irreversible capacity loss. Therefore, it is generally necessary to replenish lithium in the device.
  • the common lithium replenishment process is to add a certain lithium-containing compound to the active material layer when preparing the positive electrode of the device, which will replenish a certain amount of lithium ions during the charge and discharge process of the device.
  • lithium-containing compounds have poor air stability and are easily deteriorated due to exposure to air and contact with moisture and carbon dioxide in the air. They may even directly affect the active substances in the positive electrode. Ultimately, not only will they fail to achieve the expected lithium replenishment effect, but they may even cause the electrochemical performance of lithium-ion energy storage devices to be significantly reduced.
  • the purpose of the present invention is to provide a positive electrode plate.
  • the product also introduces a lithium replenishing layer and an isolation layer between the structures in a specific order. This not only enables the product to effectively replenish lithium and form a stable SEI layer after being assembled into a lithium battery energy storage device with an electrolyte and a negative electrode plate, but also prevents the active material from reacting with the lithium replenishing agent or its lithium replenishing product in the lithium replenishing layer, and the product has excellent electrochemical performance.
  • a positive electrode sheet comprising a current collector, an active material layer, a separation layer and a positive electrode lithium supplement layer which are sequentially arranged and stacked;
  • the isolation layer includes at least one of a conductive agent, a solid electrolyte, and a polyanion phosphate;
  • the positive electrode lithium replenishing layer contains a lithium-containing compound and a reducing agent.
  • the positive electrode plate adopts a structural distribution of current collector-active material layer-isolation layer-positive electrode lithium replenishment layer.
  • the active material layer and the positive electrode lithium replenishment layer realize electronic conduction under the action of the current collector.
  • the active material in the active material layer and the lithium-containing compound in the positive electrode lithium replenishment layer are both delithiated, thereby realizing lithium replenishment.
  • the positive electrode lithium replenishment layer will produce certain residual substances, which cooperate with the isolation layer to prevent the active material layer from directly contacting the electrolyte.
  • the isolation layer located between the active material layer and the positive electrode lithium replenishment layer contains at least one of a conductive agent, a solid electrolyte, and a polyanion phosphate, which significantly improves the ion/electron conduction efficiency of the positive electrode plate.
  • the isolation layer can effectively prevent direct contact between the active material layer and the positive electrode lithium replenishment layer.
  • the lithium-containing compounds and reducing agents in the positive electrode lithium replenishment layer will not have side reactions with the active material, and can also prevent the reaction products generated by the positive electrode lithium replenishment layer during lithium replenishment from reacting with the active material.
  • the reducing agent in the positive electrode lithium replenishment layer can fully reduce the potential of the lithium-containing compound during the lithium replenishment process, thereby further improving its lithium replenishment performance, without having to worry about excessive reaction affecting the original lithium extraction efficiency of the active material layer.
  • the active material layer includes a positive electrode active material
  • the positive electrode active material is a doped or undoped material, including at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, a ternary positive electrode material, lithium nickel manganese oxide, and a lithium-rich material.
  • the positive electrode plate described in the present invention is applicable to all types of existing common active material positive electrode systems.
  • the main reason is that the technical solution of the present invention not only separates the lithium replenishing component and the active material in the form of different layers, but also sets an isolation layer between the two layers. No matter what the lithium deintercalation rate of the active material is, it will not affect the lithium replenishing efficiency of the positive electrode lithium replenishing layer.
  • the active material layer further contains a conductive agent and a binder.
  • the conductive agent is at least one of conductive carbon black, carbon nanotubes, graphene, and carbon nanofibers;
  • the solid electrolyte is at least one of an oxide solid electrolyte, a chloride solid electrolyte, and a polymer solid electrolyte;
  • the polyanion phosphate is lithium iron phosphate (LiFePO 4 ), manganese phosphate At least one of lithium (LiMnPO 4 ), lithium manganese iron phosphate (LiMn x Fe 1-x PO 4 , wherein 0 ⁇ x ⁇ 1), lithium vanadium phosphate (Li 3 V 2 (PO 4 ) 3 ), lithium cobalt phosphate (LiCoPO 4 ), and lithium nickel phosphate (LiNiPO 4 ).
  • the isolation layer comprises a conductive agent and a solid electrolyte
  • the conductive agent is carbon nanotubes
  • the solid electrolyte is LATP (lithium aluminum titanium phosphate with sodium ion conductor (NaSICON) structure) solid electrolyte;
  • the isolation layer comprises carbon nanotubes and LATP solid electrolyte, and the mass ratio of the carbon nanotubes and LATP solid electrolyte is (1:9) to (4:6).
  • the types of conductive agent and solid electrolyte are different, the charge and discharge capacity and cycle stability of the product when used in lithium battery energy storage devices are also different.
  • the conductive agent is selected as carbon nanotubes and the solid electrolyte is selected as LATP solid electrolyte, the electrochemical performance of the positive electrode plate is better, especially when the two are combined and compounded in the above-mentioned preferred ratio, the product can exhibit the best electrochemical activity.
  • the solid electrolyte comprises a coated solid electrolyte.
  • the two can be a powder mixed structure or exist in the form of a combined layer, that is, the conductive agent in the isolation layer can exist in a layered form or a powdered form, and the solid electrolyte can be combined with the conductive agent surface in a layered form or in a powdered form.
  • the combination form is actually related to the conventional original forms of the two, and the difference in the above combination forms does not affect the final performance of the product.
  • the isolation layer further comprises an adhesive.
  • the lithium -containing compound is LiO2 , Li2O , Li2O2 , Li2NiO2 , Li2CuO2 , Li2MoO3 , Li2VO3 , Li2RuO3 , Li2MnO3 , Li2SiO3 , Li2Si2O5 , Li3VO4 , Li3 NbO 4 , Li 3 RuO 4 , Li 3 PO4 , Li 4 SiO 4 , Li 4 TiO 4 , Li 5 FeO 4 , Li 5 NbO 5 , Li 5 TaO 5 , Li 5 ReO 6 , Li 6 CoO 4 , Li 6 MnO 4 , Li 6 NiO 4 , Li 6 WO 6 , Li 6 Zr 2 O 7 , Li 7 NbO 6 , Li 7 VO 6 , Li 7 BiO 6 , Li 7 TaO 6 , Li 8 ZrO 6 , Li 8 SnO 6 , Li 8 SiO 6 , Li 8 CeO 6 , Li 8 Si
  • the reducing agent is at least one of a boride, a sulfide, a phosphide, and a reducing element;
  • the boride is at least one of cobalt boride, molybdenum boride, calcium boride, aluminum boride, magnesium boride, titanium boride, zirconium boride, silicon boride, and lanthanum boride;
  • the sulfide is at least one of sodium sulfide, iron sulfide, cobalt sulfide, molybdenum sulfide, tungsten sulfide, titanium sulfide, magnesium sulfide, calcium sulfide, copper sulfide, lanthanum sulfide, zinc sulfide, tin sulfide, nickel sulfide, and silicon sulfide;
  • the phosphide is at least one of iron phosphide, boron phosphide, nickel phosphide, sodium phosphide, and zinc phosphide;
  • the reducing element is at least one of
  • the positive electrode lithium replenishing layer further contains a conductive agent and a binder.
  • the positive electrode active material is a ternary positive electrode material and/or a lithium nickel manganese oxide positive electrode material; and the positive electrode lithium replenishing layer contains Li 4 SiO 4 and elemental sulfur.
  • the positive electrode lithium replenishing layer may also be added with phosphate positive electrode material or electrolyte.
  • the positive electrode lithium replenishing layer includes the following components in parts by weight: 80 to 96 parts of lithium-containing compound and conductive agent, 2 to 10 parts of conductive agent and 2 to 10 parts of binder.
  • the conductive agents involved in the remaining layers are not particularly limited. Those skilled in the art can choose homemade or commercially available conductive agents according to actual conditions, including but not limited to acetylene black, carbon black, carbon fiber, carbon nanotubes, Ketjen black, etc.; the binders used in the layers can also be homemade or commercially available according to actual conditions, including but not limited to polyvinyl pyrrolidone, polyvinylidene fluoride, polyethylene oxide, polytetrafluoroethylene, carboxymethyl cellulose, copolymers of styrene and butadiene, etc.
  • the thickness of the active material layer is 20 to 300 ⁇ m
  • the thickness of the isolation layer is 0.5 to 20 ⁇ m
  • the thickness of the positive electrode lithium supplement layer is 1 to 50 ⁇ m.
  • the current collector is aluminum foil.
  • Another object of the present invention is to provide a method for preparing the positive electrode sheet, comprising the following steps:
  • a positive electrode lithium replenishing layer is constructed on the isolation layer.
  • the active material layer is constructed on the current collector by coating, dipping, spraying, composite film and/or dry electrode rolling, pressing and/or bonding.
  • the isolation layer is constructed on the active material layer by coating, dipping, spraying, composite film and/or dry electrode rolling, pressing and/or bonding.
  • the positive electrode lithium replenishing layer is constructed on the isolation layer by coating, dipping, spraying, composite film and/or dry electrode rolling, pressing and/or bonding.
  • Another object of the present invention is to provide a secondary battery, comprising the positive electrode plate, a separator and a negative electrode plate described in the present invention.
  • the active lithium content in the product is effectively supplemented, and the active material in the positive electrode plate will not be affected by the lithium supplement material.
  • the first charge and discharge not only a stable SEI film can be formed, but also the energy density of the secondary battery is effectively improved due to the lithium supplement effect.
  • the secondary battery has the characteristics of high specific capacity, high rate performance and high cycle stability.
  • the negative electrode plate and the separator in the secondary battery can be made of conventional materials in the art; the preparation method of the secondary battery can be a conventional preparation method in the art.
  • Another object of the present invention is to provide an electrical device, comprising the secondary battery of the present invention, wherein the secondary battery serves as a power supply for the electrical device.
  • the beneficial effect of the present invention is that the present invention provides a positive electrode plate, which, in addition to the conventional current collector and active material layer, also introduces a lithium replenishment layer and an isolation layer in a specific order between the structures, which can not only effectively replenish lithium and form a stable SEI layer after the product is assembled into a lithium battery energy storage device with an electrolyte and a negative electrode plate, but also can avoid the active material from reacting with the lithium replenishment agent or its lithium replenishment product in the lithium replenishment layer, and the product has excellent electrochemical performance.
  • the positive electrode plate construction method is simple and can be produced on an industrial scale.
  • the carbon nanotubes described in each embodiment and comparative example are LB120-50 produced by Tiannai Technology;
  • the graphene is a product produced by Xianfeng Nano
  • the carbon fiber is a product produced by Kruder Corporation
  • the solid electrolyte LLZO is a product produced by Ganfeng Lithium;
  • the solid electrolyte LATP is a product produced by Ganfeng Lithium
  • the solid electrolyte PEO is a product produced by Inokai;
  • the other raw material additives not mentioned are all commercially available products, and the raw material additives used in the parallel experiments of the embodiments and comparative examples are all of the same kind.
  • An embodiment of the positive electrode sheet and the preparation method thereof of the present invention comprises the following steps:
  • An active material layer constructed on a 12 ⁇ m aluminum foil wherein the preparation method of the active material layer is as follows: a commercially available positive electrode active material, a conductive agent conductive carbon black superP, and a binder PVDF are weighed in a mass ratio of 95:2:3, and then NMP is added to prepare a slurry, which is coated on the aluminum foil and then dried to obtain an active material layer;
  • isolation layer constructed on the surface of the active material layer, wherein the isolation layer is prepared by weighing a conductive agent or a solid electrolyte and a binder PVDF in a mass ratio of 85:15, then adding a solvent NMP to prepare a slurry, coating the slurry on the active material layer, and then drying to obtain an isolation layer; or weighing a conductive agent, a solid electrolyte, and a binder PVDF in a mass ratio of 90:10, then adding a solvent NMP to prepare a slurry, coating the slurry on the active material layer, and then drying to obtain an isolation layer;
  • the preparation method of the positive electrode lithium replenishing layer is as follows: weighing a reducing agent and a lithium-containing compound, a conductive agent SP, and a binder PVDF according to a mass ratio of 80:15:15, then adding them to NMP to prepare a slurry, coating the slurry on the isolation layer, and then drying to obtain the positive electrode lithium replenishing layer.
  • a positive electrode sheet and a method for preparing the same comprises the following steps:
  • isolation layer constructed on the surface of the positive electrode lithium replenishing layer, wherein the isolation layer is prepared by weighing a conductive agent and a binder PVDF according to a mass ratio of 85:15, then adding a solvent NMP to prepare a slurry, coating the slurry on the positive electrode lithium replenishing layer, and then drying to obtain the isolation layer;
  • the preparation method of the active material layer is as follows: weighing a commercially available positive electrode active material, a conductive agent conductive carbon black superP, and a binder PVDF according to a mass ratio of 95:2:3, then adding a solvent NMP to prepare a slurry, coating the slurry on the isolation layer, and then drying to obtain the active material layer.
  • each layer is the same as the thickness of the corresponding layer in Example 1, and the difference from Example 1 is basically only that the construction order of the structural layers of the positive electrode plate is different.
  • a positive electrode sheet and a method for preparing the same comprises the following steps:
  • An active material layer constructed on a 12 ⁇ m aluminum foil wherein the preparation method of the active material layer is as follows: a commercially available positive electrode active material, a conductive agent conductive carbon black superP, and a binder PVDF are weighed in a mass ratio of 95:2:3, and then a solvent NMP is added to prepare a slurry, which is coated on the aluminum foil and then dried to obtain an active material layer.
  • a positive electrode lithium replenishing layer constructed on the surface of the active material layer, wherein the preparation method of the positive electrode lithium replenishing layer is: weighing a reducing agent and a lithium-containing compound, a conductive agent SP, and a binder PVDF according to a mass ratio of 80:15:15, then adding them to a solvent NMP to prepare a slurry, coating the slurry on the active material layer, and then drying to obtain the positive electrode lithium replenishing layer;
  • the preparation method of the isolation layer is as follows: weighing the conductive agent and the binder PVDF according to a mass ratio of 85:15, then adding the solvent NMP to prepare a slurry, and coating it on the positive electrode. The lithium replenishment layer is then dried to obtain an isolation layer.
  • each layer is the same as the thickness of the corresponding layer in Example 1, and the difference from Example 1 is basically only that the construction order of the structural layers of the positive electrode plate is different.
  • the positive electrode sheets prepared in each embodiment and comparative example are used to prepare lithium-ion batteries, and the specific method is as follows:
  • the positive electrode materials of LNMO series, ternary series, lithium cobalt oxide series, and lithium nickel oxide series were tested according to the following test methods: the theoretical specific capacity of LNMO was calculated as 146.7 mAh/g, the working voltage was 3.0-4.85 V, and the first charge and discharge cycle was performed at a rate of 0.05C, and then the rate was increased to 0.2C for 100 cycles, and the charge and discharge capacity of the first charge and discharge cycle was counted, and the discharge capacity after 100 cycles was counted.
  • the theoretical specific capacity of the ternary battery is calculated as 210mAh/g, the working voltage is 2.75 ⁇ 4.3V, the first charge and discharge cycle is carried out at a rate of 0.05C, and then the rate is increased to 0.2C for 100 cycles, and the charge and discharge capacity of the first charge and discharge cycle is counted, and the discharge capacity after 100 cycles is counted.
  • the theoretical specific capacity of lithium cobalt oxide is calculated as 200mAh/g, the working voltage is 3 ⁇ 4.45V, the first charge and discharge cycle is carried out at a rate of 0.05C, and then the rate is increased to 0.2C for 100 cycles, and the charge and discharge capacity of the first charge and discharge cycle is counted, and the discharge capacity after 100 cycles is counted.
  • the theoretical specific capacity of lithium nickel oxide is calculated as 220mAh/g, the working voltage is 2.75 ⁇ 4.3V, the first charge and discharge cycle is carried out at a rate of 0.05C, and then the rate is increased to 0.2C for 100 cycles, and the charge and discharge capacity of the first charge and discharge cycle is counted, and the discharge capacity after 100 cycles is counted.
  • the semi-finished products prepared in steps (1) and/or step (2) of Examples 1 to 8 and Comparative Examples 1 and 2 are also tested as positive electrode sheets and named as step (1) and step (2), respectively (for example, step (1) in Example 1 only obtains a positive electrode sheet containing a current collector and an active material layer, and the semi-finished product is applied to the same test and named as Example 1-(1)).
  • each positive electrode sheet in Table 2 shows that, under the conditions of different thicknesses, different active material layers, isolation layers and positive electrode lithium replenishing layer compositions, the positive electrode sheets of each embodiment of the present invention are significantly improved in first efficiency and cycle stability compared with a single current collector-active material layer positive electrode sheet or a current collector-active material layer-isolation layer positive electrode sheet, indicating that in the positive electrode sheet, the positive electrode lithium replenishing layer can effectively replenish lithium, and under the joint action of the isolation layer and the positive electrode lithium replenishing layer, the product has a high content of reversible lithium ion insertion and deintercalation, which can achieve long-term positive and negative electrode conduction.
  • the isolation layer is composed of a conductive agent and a solid electrolyte as components
  • the performance improvement effect is higher than that of products with a single conductive agent or a solid electrolyte as components.
  • the types of conductive agents and solid electrolytes are different, the electrochemical properties of the positive electrode plates are also different.
  • the discharge capacity of the product can still reach 195.6 mAh/g after 100 cycles when used alone, and when combined with a solid electrolyte, the electrochemical performance of the product is further improved, and when combined with LATP solid electrolytes, the discharge capacity can reach a higher 205.2 mAh/g after 100 cycles, which is much higher than the effect of carbon nanotubes and other solid electrolytes combined as isolation layers.
  • the mass ratio of the two is not in the range of (1:9) to (4:6), the best performance improvement may not be achieved.
  • Examples 25 to 30 show that polyanion phosphates such as lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, and lithium nickel phosphate can also achieve the same effect as an isolation layer.
  • polyanion phosphates such as lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, and lithium nickel phosphate can also achieve the same effect as an isolation layer.
  • the product of Comparative Example 1 was prepared with a structure of current collector-positive electrode lithium replenishing layer-barrier layer-active material layer when constructing the structural layer. Although it also had a lithium replenishing layer and a barrier layer, the electrochemical performance of the product was poor. Obviously, the two-layer structure did not effectively inhibit the direct contact between the active material layer and the electrolyte. The product performance was even comparable to the positive electrode sheet with only the current collector and the active material layer obtained in step (1) of Example 1. Similarly, the positive electrode sheet obtained in Comparative Example 2 with an inappropriate configuration did not have ideal lithium replenishing performance.
  • reference products 1 to 7 were prepared according to the similar methods described in Examples 1 to 7. The difference between these reference products and the products of Examples 1 to 7 is that after the active material layer is constructed to the current collector in the preparation method, the isolation layer is not further constructed between the active material layer and the current collector.
  • the positive electrode lithium replenishing layer is not constructed on the material layer, but directly constructed on the active material layer, and the other parameters and process methods are the same as those of the corresponding embodiments.
  • reference product 8 is prepared according to a similar method as described in comparative example 1.
  • the isolation layer of the present invention does not only function as a conventional conductive agent in the positive electrode sheet.
  • the positive electrode lithium replenishment layer has a very limited effect on the lithium replenishment of the overall button cell. Both the initial capacity and the retention capacity after 100 cycles are close to that of the positive electrode with only a current collector and an active material layer.
  • the control product 8 shows performance degradation compared to the product of comparative example 1, indicating that the isolation layer of the present invention also effectively inhibits the positive electrode lithium replenishment layer and its reactants from contacting the active material layer, avoiding mutual side reactions between the two structural layers.
  • the control product 26 shows that the performance of the product is also significantly improved after the isolation layer containing lithium iron phosphate is included, and lithium iron phosphate is not only used as an active material as an isolation layer.

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Abstract

一种正极极片及其制备方法与应用，属于锂电储能技术领域。所述正极极片除了常规的集流体和活性物质层外，还在结构间按照特定顺序引入了补锂层和隔离层，不仅可以使得产品在与电解液、负极极片组装成锂电储能器件后能够有效补锂并形成稳定的SEI层，同时能够避免活性物质与补锂层中的补锂剂或其补锂产物发生反应，产品的电化学性能优异。所述正极极片构建方法简单，可实现工业化规模生产。

Description

一种正极极片及其制备方法与应用 技术领域
本发明涉及锂电储能技术领域，具体涉及一种正极极片及其制备方法与应用。
背景技术
锂电储能器件由于在首次充放电循环过程中会在负极界面生成一层固态电解质界面(SEI)膜，导致一部分活性锂失活并且造成不可逆的容量损失，因此，一般需要对所述器件进行补锂。现有常见的补锂工艺是在器件的正极极片制备时在活性物质层中加入一定的含锂化合物，其会在器件充放电过程中补充一定量的锂离子。
然而，含锂化合物空气稳定性差，容易因暴露在空气中与空气中的水分和二氧化碳接触而反应变质，甚至会直接影响到正极极片中的活性物质，最终不仅无法实现预期的补锂功效，甚至还会导致锂电储能器件的电化学性能显著降低。
发明内容
基于现有技术存在的缺陷，本发明的目的在于提供了一种正极极片，该产品除了常规的集流体和活性物质层外，还在结构间按照特定顺序引入了补锂层和隔离层，不仅可以使得产品在与电解液、负极极片组装成锂电储能器件后能够有效补锂并形成稳定的SEI层，同时能够避免活性物质与补锂层中的补锂剂或其补锂产物发生反应，产品的电化学性能优异。
为了达到上述目的，本发明采取的技术方案为：
一种正极极片，包括依次排列层叠的集流体、活性物质层、隔离层以及正极补锂层；
所述隔离层包括导电剂、固态电解质、聚阴离子磷酸盐中的至少一种；
所述正极补锂层中含有含锂化合物及还原剂。
现有工艺中，为了对正极极片进行补锂，常常在活性物质层中加入补锂剂， 但这类方法经过人们验证发现其效果并不理想，皆因补锂剂虽然能够有效为活性物质层提供额外的锂离子，但活性物质依然会和电解液直接接触并迅速生产SEI膜，因此最终的锂电储能器件的锂离子传导效率依然被SEI膜的生成情况所牵制，同时补锂剂本身也会和电解液甚至是活性物质发生反应，尤其是产生的一些诸如氧气等产物，可能导致活性物质发生氧化，最终不仅无法达到有效的补锂效果，甚至可能使得锂电储能器件的容量及循环性能迅速衰减。因此，在本发明技术方案中，所述正极极片采用集流体-活性物质层-隔离层-正极补锂层的结构分布，在应用于锂电储能器件时，活性物质层和正极补锂层在集流体作用下实现电子导通，充电过程中，活性物质层中的活性材料和正极补锂层中的含锂化合物均发生脱锂，从而实现补锂，此时正极补锂层会产生一定的残余物质，协同隔离层共同阻止活性物质层与电解液直接接触，因此正极表面的SEI膜的稳定性更高，锂电储能器件的循环稳定性更好；另一方面，位于活性物质层和正极补锂层的隔离层中包含导电剂、固态电解质、聚阴离子磷酸盐中的至少一种，对于正极极片的离子/电子的传导效率有显著提升，而最主要的是，该隔离层能够有效阻止活性物质层和正极补锂层间的直接接触，正极补锂层中的含锂化合物及还原剂均不会和活性物质发生副反应，同时也可以阻止正极补锂层在补锂时产生的反应产物与活性物质发生反应。在此基础下，正极补锂层中的还原剂可以充分地降低含锂化合物在补锂过程中的电位，从而进一步提升其补锂性能，而无需担心过分反应影响到活性物质层原本的脱嵌锂效率。
优选地，所述活性物质层包括正极活性物质，所述正极活性物质为掺杂或未掺杂材料，包括钴酸锂、镍酸锂、锰酸锂、三元正极材料、镍锰酸锂、富锂材料中的至少一种。
本发明所述正极极片对于各类现有常见的活性材料正极体系均可适用，主要原因便在于本发明技术方案不仅将补锂成分和活性材料以不同层的形式分离开来，同时还在两层之间设置隔离层，无论活性材料的锂脱嵌速率如何，均不会影响正极补锂层的补锂效率。
更优选地，所述活性物质层还含有导电剂和粘结剂。
优选地，所述导电剂为导电炭黑、碳纳米管、石墨烯、碳纳米纤维中的至少一种；所述固态电解质为氧化物固态电解质、氯化物固态电解质、聚合物固态电解质中的至少一种；所述聚阴离子磷酸盐为磷酸铁锂(LiFePO4)、磷酸锰 锂(LiMnPO4)、磷酸锰铁锂(LiMnxFe1-xPO4，其中0＜x＜1)、磷酸钒锂(Li3V2(PO4)3)、磷酸钴锂(LiCoPO4)、磷酸镍锂(LiNiPO4)中的至少一种。
更优选地，所述隔离层包括导电剂和固态电解质；
更优选地，所述导电剂为碳纳米管，所述固态电解质为LATP(钠离子导体(NaSICON)结构磷酸铝钛锂)固态电解质；
更优选地，所述隔离层包括碳纳米管和LATP固态电解质，两者的质量比为(1:9)～(4:6)。
发明人发现，在正极极片补锂及循环过程中，隔离层中的导电剂、固态电解质以及聚阴离子磷酸盐单独使用时均可以有效提升正极极片的锂离子/电子传导速率，而当导电剂和固态电解质的种类选择不同，产品应用在锂电储能器件时的充放电容量及循环稳定性也有所差异，当导电剂选择碳纳米管，固态电解质选择LATP固态电解质时，正极极片的电化学性能更优，尤其是两者结合并以上述优选配比复配时，产品可展现出最优的电化学活性。
优选地，所述固态电解质包含包覆后的固态电解质。
需要说明的是，本发明所述隔离层中导电剂和固态电解质在混合使用时，两者可以是粉末状混合结构的，也可以是以结合层形式存在的，即所述隔离层中导电剂可以以层状形式或粉末形式存在，而固态电解质可以以层状形式结合在导电剂表面，也可以以粉末形式结合在导电剂表面，两者的位置互换情况同理。本领域技术人员应当知悉该结合形式实际与两者的常规原有形态相关，上述结合形式的差异并不影响产品的最终性能。
优选地，所述隔离层还包括粘结剂。
优选地，所述含锂化合物为LiaMbOc，其中a＝1～12，M为Ni、Cu、Mo、V、Ru、Mn、Si、Nb、Ti、Fe、Ta、Re、Co、W、Zr、Bi、Sn、Ce中的至少一种，b＝0～2，c＝0～11；
更优选地，所述含锂化合物为LiO2、Li2O、Li2O2、Li2NiO2、Li2CuO2、Li2MoO3、Li2VO3、Li2RuO3、Li2MnO3、Li2SiO3、Li2Si2O5、Li3VO4、Li3NbO4、Li3RuO4、Li3PO4、Li4SiO4、Li4TiO4、Li5FeO4、Li5NbO5、Li5TaO5、Li5ReO6、Li6CoO4、Li6MnO4、Li6NiO4、Li6WO6、Li6Zr2O7、Li7NbO6、Li7VO6、Li7BiO6、Li7TaO6、Li8ZrO6、Li8SnO6、Li8SiO6、Li8CeO6、Li8MoO6、Li8MnO6、Li8Nb2O9、Li12Nb2O11中的至少一种。
优选地，所述还原剂为硼化物、硫化物、磷化物、还原性单质中的至少一种；
更优选地，所述硼化物为硼化钴、硼化钼、硼化钙、硼化铝、硼化镁、硼化钛、硼化锆、硼化硅、硼化镧中的至少一种；所述硫化物为硫化钠、硫化铁、硫化钴、硫化钼、硫化钨、硫化钛、硫化镁、硫化钙、硫化铜、硫化镧、硫化锌、硫化锡、硫化镍、硫化硅中的至少一种；所述磷化物为磷化铁、磷化硼、磷化镍、磷化钠、磷化锌中的至少一种；所述还原性单质为单质硫、单质磷、单质硼、单质硅、单质铝、单质锗、单质砷、单质碘、单质钒、单质锰、单质铁、单质钴、单质镍、单质锡中的至少一种。
优选地，所述正极补锂层还含有导电剂和粘结剂。
优选地，所述正极活性物质为三元正极材料和/或镍锰酸锂正极材料；所述正极补锂层含有Li4SiO4及单质硫。
优选地，所述正极补锂层还可以加入磷酸盐正极材料或电解质。
更优选地，所述正极补锂层中，包括以下重量份的组分：含锂化合物与导电剂80～96份、导电剂2～10份以及粘结剂2～10份。
需要说明的是，除本发明所限定的隔离层外，其余层所涉及的导电剂并没有特别限制，本领域技术人员可以根据实际情况选择自制或市售的导电剂种类，包括但不限于乙炔黑、炭黑、碳纤维、碳纳米管、科琴黑等；所述各层中使用的粘结剂也可以根据实际情况选择自制或市售的种类，包括但不限于聚乙烯吡咯烷酮、聚偏氟乙烯、聚环氧乙烷、聚四氟乙烯、羧甲基纤维素、苯乙烯与丁二烯的共聚物等。
优选地，所述正极极片中，活性物质层的厚度为20～300μm、隔离层的厚度为0.5～20μm，正极补锂层的厚度为1～50μm。
根据实际需求，本领域技术人员可以在正极极片中设置不同厚度的结构层以用于不同正极活性材料、电解液体系的锂电储能器件。
优选地，所述集流体为铝箔。
本发明的另一目的在于提供所述正极极片的制备方法，包括以下步骤：
在集流体上构建活性物质层；
在活性物质层上构建隔离层；
在隔离层上构建正极补锂层。
优选地，所述活性物质层采用涂覆、浸蘸、喷涂、复合膜和/或干法电极方式辊压、压制和/或黏合方式构建在集流体上。
优选地，所述隔离层采用涂覆、浸蘸、喷涂、复合膜和/或干法电极方式辊压、压制和/或黏合方式构建在活性物质层上。
优选地，所述正极补锂层采用涂覆、浸蘸、喷涂、复合膜和/或干法电极方式辊压、压制和/或黏合方式构建在隔离层上。
本发明的另一目的在于提供一种二次电池，包括本发明所述正极极片、隔膜以及负极极片。
本发明所述正极极片应用于二次电池中时，产品中的活性锂含量有效得到补充，同时正极极片中的活性物质不会受到补锂材料的影响，在首次充放电后，不仅可形成稳定的SEI膜，同时二次电池的能量密度因为补锂作用而得到有效提升，所述二次电池具有高比容量、高倍率性能和高循环稳定性的特点。
需要说明的是，二次电池中负极极片、隔膜均可采用本领域常规的材料；二次电池的制备方法可以为本领域常规的制备方法。
本发明的再一目的在于提供一种用电装置，包括本发明所述二次电池，所述二次电池作为所述用电装置的供电电源。
本发明的有益效果在于，本发明提供了一种正极极片，该产品除了常规的集流体和活性物质层外，还在结构间按照特定顺序引入了补锂层和隔离层，不仅可以使得产品在与电解液、负极极片组装成锂电储能器件后能够有效补锂并形成稳定的SEI层，同时能够避免活性物质与补锂层中的补锂剂或其补锂产物发生反应，产品的电化学性能优异。所述正极极片构建方法简单，可实现工业化规模生产。
具体实施方式
为了更好地说明本发明的目的、技术方案和优点，下面将结合具体实施例及对比例对本发明作进一步说明，其目的在于详细地理解本发明的内容，而不是对本发明的限制。本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明的保护范围。本发明实施所涉及的实验试剂及仪器，除非特别说明，均为常用的普通试剂及仪器。
各实施例和对比例中所述碳纳米管为天奈科技生产LB120-50；
所述石墨烯为先丰纳米生产产品；
所述碳纤维为科路得公司生产产品；
所述固态电解质LLZO为赣锋锂业生产产品；
所述固态电解质LATP为赣锋锂业生产产品；
所述固态电解质PEO为伊诺凯生产产品；
其余未提及的原料助剂，均为市售产品，且各实施例和对比例在平行实验中所使用的所述原料助剂均为同种。
实施例1～24
本发明所述正极极片及其制备方法的一种实施例，本实施例所述正极极片的制备方法，包括以下步骤：
(1)在12μm铝箔上构建的活性物质层，该活性物质层的制备方法为：将市售正极活性材料、导电剂导电炭黑superP、粘结剂PVDF按照质量比95:2:3称量，随后加入NMP配制浆料，涂覆在铝箔上，随后干燥，得到活性物质层；
(2)在活性物质层表面构建的隔离层，该隔离层的制备方法为：将导电剂或固态电解质、粘结剂PVDF按照质量比85:15称量，随后加入溶剂NMP配制浆料，涂覆在活性物质层上，随后干燥，得到隔离层；或者将导电剂与固态电解质、粘结剂PVDF按照质量比90:10称量，随后加入溶剂NMP配制浆料，涂覆在活性物质层上，随后干燥，得到隔离层；
(3)在隔离层表面构建正极补锂层，该正极补锂层的制备方法为：将还原剂及含锂化合物、导电剂SP、粘结剂PVDF按照质量比80:15:15称量，随后加入NMP中配制浆料，涂覆在隔离层上，随后干燥，得到正极补锂层。
各原料的配比及组成如表1所示。
表1



对比例1
一种正极极片及其制备方法，本实施例所述正极极片的制备方法，包括以下步骤：
(1)在12μm铝箔上构建的正极补锂层，该正极补锂层的制备方法为：将还原剂及含锂化合物、导电剂SP、粘结剂PVDF按照质量比80:15:15称量，随后加入溶剂NMP中配制浆料，涂覆在铝箔上，随后干燥，得到正极补锂层；
(2)在正极补锂层表面构建的隔离层，该隔离层的制备方法为：将导电剂、粘结剂PVDF按照质量比85:15称量，随后加入溶剂NMP配制浆料，涂覆在正极补锂层上，随后干燥，得到隔离层；
(3)在隔离层表面构建活性物质层，该活性物质层的制备方法为：将市售正极活性材料、导电剂导电炭黑superP、粘结剂PVDF按照质量比95:2:3称量，随后加入溶剂NMP配制浆料，涂覆在隔离层上，随后干燥，得到活性物质层。
各层的厚度与实施例1对应层的厚度相同，与实施例1的差别基本仅在于，所述正极极片的结构层构建顺序不同。
对比例2
一种正极极片及其制备方法，本实施例所述正极极片的制备方法，包括以下步骤：
(1)在12μm铝箔上构建的活性物质层，该活性物质层的制备方法为：将市售正极活性材料、导电剂导电炭黑superP、粘结剂PVDF按照质量比95:2:3称量，随后加入溶剂NMP配制浆料，涂覆在铝箔上，随后干燥，得到活性物质层
(2)在活性物质层表面构建的正极补锂层，该正极补锂层的制备方法为：将还原剂及含锂化合物、导电剂SP、粘结剂PVDF按照质量比80:15:15称量，随后加入溶剂NMP中配制浆料，涂覆在活性物质层上，随后干燥，得到正极补锂层；
(3)在正极补锂层表面构建隔离层，该隔离层的制备方法为：将导电剂、粘结剂PVDF按照质量比85:15称量，随后加入溶剂NMP配制浆料，涂覆在正 极补锂层上，随后干燥，得到隔离层。
各层的厚度与实施例1对应层的厚度相同，与实施例1的差别基本仅在于，所述正极极片的结构层构建顺序不同。
效果例1
为了验证本发明所述正极极片的使用效果，将各实施例和对比例制备的正极极片应用于制备锂离子电池，具体方法为：
以商业石墨、导电炭黑以及粘结剂PVDF按照93:2:5混料配浆，随后涂布制备负极极片，以该负极极片、各实施例和对比例的正极极片、1M的LiPF6溶解在EC/DMC(1：1，体积比)为电解质(购自德国巴斯夫电解质公司)在手套箱中组织扣式电池。各扣式电池静置24h后，针对各电池正极材料种类的不同，对于LNMO系、三元系、钴酸锂系、镍酸锂系的正极材料，分别按照以下测试方法进行测试：以LNMO的理论比容量算为146.7mAh/g，工作电压为3.0～4.85V在0.05C倍率下进行首次充放电循环，随后增大倍率至0.2C循环100次，统计首次充放电循环的充电和放电容量，并统计循环100次后的放电容量。以三元的理论比容量算为210mAh/g，工作电压为2.75～4.3V在0.05C倍率下进行首次充放电循环，随后增大倍率至0.2C循环100次，统计首次充放电循环的充电和放电容量，并统计循环100次后的放电容量。以钴酸锂的理论比容量算为200mAh/g，工作电压为3～4.45V在0.05C倍率下进行首次充放电循环，随后增大倍率至0.2C循环100次，统计首次充放电循环的充电和放电容量，并统计循环100次后的放电容量。以镍酸锂的理论比容量算为220mAh/g，工作电压为2.75～4.3V在0.05C倍率下进行首次充放电循环，随后增大倍率至0.2C循环100次，统计首次充放电循环的充电和放电容量，并统计循环100次后的放电容量。
同时，为了方便比较产品中每个结构层的作用性，将各实施例1～8和对比例1和2步骤(1)和/或步骤(2)制备的半成品同样作为正极极片进行测试，并分别以步骤(1)和步骤(2)命名(例如，实施例1中步骤(1)仅得到了含有集流体和活性物质层的正极极片，该半成品应用于相同测试，并命名为实施例1-(1))。
结果如表2所示。
表2






从表2各正极极片性能可以看出，在不同厚度、不同活性物质层、隔离层和正极补锂层组成的情况下，本发明各实施例的正极极片均比单独的集流体-活性物质层正极极片或者集流体-活性物质层-隔离层正极极片在首效及循环稳定性方面有显著的提升，说明在所述正极极片中，正极补锂层可以有效实现补锂，并在隔离层和正极补锂层的共同作用下，产品的可逆脱嵌锂离子含量较多，可以实现长时间正负极传导。其中，当隔离层以导电剂和固态电解质复配作为组分时，相比于单独的导电剂或者固态电解质作为组分的产品的性能提升效果更高，而当导电剂和固态电解质种类选择不同时，正极极片的电化学性能也存在差异，根据实施例8～19产品性能可以看出，当导电剂为碳纳米管时，在单独使用下的产品在循环100次后的放电容量依然可以达到195.6mAh/g，而当与固态电解质相结合时，产品的电化学性能进一步提升，并在和LATP固态电解质结合时在循环100次后的放电容量可以达到较高的205.2mAh/g，远高于碳纳米管和其他固态电解质结合时作为隔离层的效果。不过，此时若两者的质量比不在(1:9)～(4:6)范围时，可能无法实现最佳的性能提升，如实施例23和24产品所示，其性能与导电剂或固态电解质单独使用的实施例9和实施例15差异不大，另外实施例25～30表明聚阴离子磷酸盐磷酸铁锂、磷酸锰锂、磷酸锰铁锂、磷酸钒锂、磷酸钴锂、磷酸镍锂等作为隔离层也可以达到同样的效果。
相比之下，对比例1产品在结构层构建时，以集流体-正极补锂层-阻隔层-活性物质层的结构制备，虽然同样具有补锂层和阻隔层，但产品的电化学性能差，显然这两层结构并没有有效抑制活性物质层与电解液的直接接触，产品性能甚至与实施例1步骤(1)所得的只有集流体和活性物质层的正极极片相当。同理，采用不合适构型的对比例2所得正极极片也不具备理想的补锂性能。
进一步地，为了单独考究本发明所述正极极片中隔离层的功能性，按照实施例1～7所述类似方法制备对照品1～7，这些对照品与实施例1～7产品的差别仅在于，在制备方法中构建活性物质层至集流体后，不进一步构建隔离层在活性 物质层上，而是直接将正极补锂层构建在活性物质层上，其余各参数和工艺方法均同各对应实施例。同理，按照对比例1所述类似方法制备对照品8，该对照品与对比例1产品的差别仅在于，在制备方法中，在集流体上构建正极补锂层后，直接进一步构建活性物质层，其余各参数和工艺方法均同对比例1。按照实施例26，将隔离层中的磷酸铁锂直接加到三元活性物质中，不设置隔离层，再在活性物质表面构建正极补锂层的方法制备对照品26。
将对照品1～8进行上述相同测试，结果如表3所示。
表3
从表3与表2对比可知，本发明所述隔离层在正极极片中并不仅仅只是作为常规的导电剂发挥功能，以实施例1和对照品1的测试结果为例，可以看出， 在缺少隔离层时，正极补锂层对于整体扣式电池的补锂效果非常有限，无论是初始容量亦或是循环100次后的保留容量均与只有集流体和活性物质层的正极极片接近，而在含有隔离层后，产品的性能提升显著，而对照品8相比于对比例1产品同样出现了性能衰减，说明本发明所述隔离层还有效抑制了正极补锂层及其反应物与活性物质层相接触，避免两种结构层间发生相互副反应。对照品26相比于实施例26，说明含有磷酸铁锂的隔离层后，产品的性能也提升显著，磷酸铁锂作为隔离层并不只是充当活性物质使用。
最后所应当说明的是，以上实施例仅用以说明本发明的技术方案而非对本发明保护范围的限制，尽管参照较佳实施例对本发明作了详细说明，本领域的普通技术人员应当理解，可以对本发明的技术方案进行修改或者等同替换，而不脱离本发明技术方案的实质和范围。

Claims (12)

  1. 一种正极极片，其特征在于，包括依次排列层叠的集流体、活性物质层、隔离层以及正极补锂层；
    所述隔离层包括导电剂、固态电解质、聚阴离子磷酸盐中的至少一种；
    所述正极补锂层中含有含锂化合物及还原剂。
  2. 如权利要求1所述正极极片，其特征在于，所述活性物质层包括正极活性物质，所述正极活性物质为掺杂或未掺杂材料，包括钴酸锂、镍酸锂、锰酸锂、三元正极材料、镍锰酸锂、富锂材料中的至少一种。
  3. 如权利要求2所述正极极片，其特征在于，所述导电剂为导电炭黑、碳纳米管、石墨烯、碳纳米纤维中的至少一种；所述固态电解质为氧化物固态电解质、氯化物固态电解质、聚合物固态电解质中的至少一种，所述聚阴离子磷酸盐为磷酸铁锂、磷酸锰锂、磷酸锰铁锂、磷酸钒锂、磷酸钴锂、磷酸镍锂中的至少一种。
  4. 如权利要求3所述正极极片，其特征在于，所述隔离层包括导电剂和固态电解质。
  5. 如权利要求3所述正极极片，其特征在于，所述固态电解质包含包覆后的固态电解质。
  6. 如权利要求4所述正极极片，其特征在于，所述隔离层包括碳纳米管和LATP固态电解质，两者的质量比为(1:9)～(4:6)。
  7. 如权利要求6所述正极极片，其特征在于，所述隔离层包括碳纳米管和LATP固态电解质，两者的质量比为2:8；所述正极活性物质为三元正极材料和/或镍锰酸锂正极材料；所述正极补锂层含有Li4SiO4及单质硫。
  8. 如权利要求1所述正极极片，其特征在于，所述含锂化合物为LiaMbOc，其中a＝1～12，M为Ni、Cu、Mo、V、Ru、Mn、Si、Nb、Ti、Fe、Ta、Re、Co、W、Zr、Bi、Sn、Ce中的至少一种，b＝0～2，c＝0～11；所述还原剂为硼化物、硫化物、磷化物、还原性单质中的至少一种。
  9. 如权利要求1所述正极极片，其特征在于，所述正极极片中，活性物质层的厚度为20～300μm、隔离层的厚度为0.5～20μm，正极补锂层的厚度为1～50μm。
  10. 如权利要求1～9任一项所述正极极片的制备方法，其特征在于，包括以下步骤：
    在集流体上构建活性物质层；
    在活性物质层上构建隔离层；
    在隔离层上构建正极补锂层。
  11. 一种二次电池，其特征在于，包括权利要求1～9任一项所述正极极片、隔膜以及负极极片。
  12. 一种用电装置，其特征在于，包括权利要求11所述二次电池，所述二次电池作为所述用电装置的供电电源。
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WO2023141972A1 (zh) * 2022-01-28 2023-08-03 宁德时代新能源科技股份有限公司 正极极片及包含所述极片的锂离子电池

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CN103401016A (zh) * 2013-08-05 2013-11-20 宁德时代新能源科技有限公司 高能量密度锂离子电池
CN106384808A (zh) * 2016-11-29 2017-02-08 湖南三迅新能源科技有限公司 一种锂离子电池正极片及其制备方法、锂离子电池
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