WO2022077685A1 - 一种混合电容器的正极及其制备方法和用途 - Google Patents

一种混合电容器的正极及其制备方法和用途 Download PDF

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Publication number
WO2022077685A1
WO2022077685A1 PCT/CN2020/128952 CN2020128952W WO2022077685A1 WO 2022077685 A1 WO2022077685 A1 WO 2022077685A1 CN 2020128952 W CN2020128952 W CN 2020128952W WO 2022077685 A1 WO2022077685 A1 WO 2022077685A1
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Prior art keywords
positive electrode
optionally
conductive agent
lithium
binder
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PCT/CN2020/128952
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English (en)
French (fr)
Inventor
罗垂意
卜芳
祝媛
袁中直
刘建华
刘金成
Original Assignee
惠州亿纬锂能股份有限公司
惠州亿纬创能电池有限公司
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Application filed by 惠州亿纬锂能股份有限公司, 惠州亿纬创能电池有限公司 filed Critical 惠州亿纬锂能股份有限公司
Priority to KR1020227044364A priority Critical patent/KR102709895B1/ko
Priority to EP20957461.5A priority patent/EP4145476A4/en
Priority to JP2022575357A priority patent/JP2023528650A/ja
Priority to CA3181237A priority patent/CA3181237A1/en
Priority to US18/008,412 priority patent/US20240242897A1/en
Publication of WO2022077685A1 publication Critical patent/WO2022077685A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/50—Electrodes characterised by their material specially adapted for lithium-ion capacitors, e.g. for lithium-doping or for intercalation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/24—Electrodes characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/26—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features
    • H01G11/28—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features arranged or disposed on a current collector; Layers or phases between electrodes and current collectors, e.g. adhesives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H01G11/38—Carbon pastes or blends; Binders or additives therein
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
    • H01G11/86—Processes for the manufacture of hybrid or EDL capacitors, or components thereof specially adapted for electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—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
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/04—Hybrid capacitors
    • H01G11/06—Hybrid capacitors with one of the electrodes allowing ions to be reversibly doped thereinto, e.g. lithium ion capacitors [LIC]
    • 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
    • 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
    • Y02E60/13—Energy storage using capacitors

Definitions

  • the application belongs to the technical field of hybrid capacitors, and relates to a positive electrode of a hybrid capacitor and a preparation method and application thereof.
  • Activated carbon is one of the commonly used carbon materials, but the specific capacitance of activated carbon is generally between 25-35F/g, and the compaction density is only 0.5- 0.6g/m 2 , the energy density of capacitors using pure activated carbon as electrodes is only 2-10Wh/kg, which is severely limited.
  • the activated carbon electrode is mainly obtained by making a water-based slurry and coating it on the surface of the foil for drying and rolling.
  • lithium-ion capacitors have the advantages of high energy density and power density, high electrostatic capacity and longer cycle life than lithium-ion batteries, and are expected to be used in new energy vehicles, wind energy and Internet of Things. field is widely used.
  • CN104538194A discloses a preparation method of lithium ion capacitor (LIC) using pre-lithiated hard carbon negative electrode, using commercialized activated carbon as positive electrode, hard carbon as negative electrode, 1M LiPF 6 /EC+DEC as electrolyte to assemble lithium ions capacitor.
  • the LIC with a lithium intercalation capacity of 400mAh/g has the highest energy density and power density of 76.5Wh/kg and 5.1kW/kg, respectively, and the energy retention rate is still as high as 92.0% after 1000 cycles.
  • the energy density of the lithium-ion capacitor after 15h prelithiation can reach 97.2Wh/kg, with the smallest impedance and good cycle performance (the energy retention rate is 91.2% after 1000 cycles at a current density of 1A/g).
  • the mass ratio of positive and negative electrodes is 2.2
  • the energy retention rate is 57.0%.
  • the capacitor has a very small charge transfer internal resistance (10.4), and the maximum energy density and power density are 88.7Wh/kg and 12kW/kg, respectively.
  • the preparation method provided by the invention is relatively complex, time-consuming, and costly, and cannot meet the requirements of the Internet of Things power supply for rate performance and energy density.
  • CN104617335A discloses a low-temperature chemical power source and a manufacturing method thereof.
  • the manufacturing method includes the following steps: 1) preparing a battery cell, and welding the tabs to seal the battery core into a shell and then drying; 2) after the battery core is packaged into a shell and completed Drying, and completing one injection; 3) Formation treatment of lithium-ion capacitors or lithium-ion batteries; 4) The second injection of the completed monomer; 5) Reshaping the monomer for subsequent processing .
  • two injections are taken, the purpose of the first injection is mainly to form a film, and the purpose of the second injection is to improve the electrical conductivity and low-temperature characteristics of the device.
  • the invention improves the low temperature performance of the chemical power supply, it still cannot meet the requirements of the Internet of Things power supply for the working temperature of -40°C to 125°C.
  • the purpose of the present application is to provide a positive electrode of a hybrid capacitor and its preparation method and use.
  • the positive electrode of the hybrid capacitor by improving the formula and process of the conventional positive electrode, solves the problems of the low energy density of the carbon-based capacitor and the need for pre-lithium intercalation treatment of the negative electrode, improves the energy density and rate performance of the device, and can meet the requirements of -40°C- 125 °C high rate pulse discharge.
  • the method of the present application is particularly suitable for improving the room temperature rate performance and the low temperature rate performance, and at the same time, realizes that the negative electrode is free of pre-lithium, and reduces the production cost.
  • the present application provides a positive electrode for a hybrid capacitor, the positive electrode includes a current collector, an adhesive layer and a positive electrode material layer sequentially located on the surface of the current collector, the adhesive layer includes a first binder, the The positive electrode material layer includes a second binder, a conductive agent, a positive electrode active material and a lithium-rich compound.
  • a bonding layer is arranged between the current collector and the positive electrode material layer, which improves the bonding ability of the positive electrode material and the current collector and reduces the internal resistance of the electrode sheet; the lithium-rich compound and the positive electrode active material provide lithium during the charging process.
  • the ions enter the negative electrode and perform lithium intercalation, so that the negative electrode can be exempted from the pre-lithiation step; the interaction of the above substances improves the rate performance of the positive electrode, which can meet the needs of high-rate charge and discharge.
  • the thickness of the adhesive layer is 0.5-10 ⁇ m, such as 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 4 ⁇ m, 6 ⁇ m, 8 ⁇ m, 9 ⁇ m, or 10 ⁇ m, etc., and optionally 1-5 ⁇ m. If the thickness is less than 0.5 ⁇ m, the adhesive force of the conductive adhesive layer to the powder is too small, which cannot effectively reduce the resistance of the pole piece and prevent the powder from falling off; if the thickness is greater than 10 ⁇ m, the thickness of the pole piece is too large, which is not conducive to improving the device. Energy Density.
  • the conductive agent includes a first conductive agent and a second conductive agent
  • the first conductive agent includes at least one of graphite powder, conductive carbon black or acetylene black
  • the second conductive agent includes graphite At least one of an olefinic material and a one-dimensional carbon material.
  • graphene-like materials and/or one-dimensional carbon materials build a three-dimensional conductive network, and at least one particle of graphite powder, conductive carbon black or acetylene black is dispersed in the interior and/or surface of the conductive network, forming a perfect The conductive system can improve the electrical conductivity of the material.
  • the positive electrode active material includes a lithium-containing positive electrode active material and a carbon-based positive electrode active material.
  • the lithium-containing positive electrode active material includes lithium cobalt oxide, lithium nickel oxide, lithium manganate, lithium iron phosphate, nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material, or nickel-cobalt-manganese-aluminum quaternary material. Any one or a combination of at least two of them can be selected as any one or at least two of lithium nickelate, nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material or nickel-cobalt-manganese-aluminum quaternary material. combination.
  • lithium cobalt oxide and lithium manganate lithium manganate and lithium iron phosphate, lithium iron phosphate and lithium cobalt oxide
  • nickel-cobalt-manganese ternary material and nickel-cobalt-aluminum ternary material nickel-cobalt-aluminum ternary material element material and nickel-cobalt-manganese-aluminum quaternary material, which can be selected from any one or a combination of at least two of lithium nickelate, nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material or nickel-cobalt-manganese-aluminum quaternary material .
  • the carbon-based positive active material includes any one or a combination of at least two of activated carbon, graphene, doped graphene or porous biomass carbon.
  • the carbon-based positive active material has a relatively large specific surface area, generally above 1500 m 2 /g (for example, 1500 m 2 /g, 1600 m 2 /g, 1700 m 2 /g, 1800 m 2 /g, 2000 m 2 /g g or 2100m 2 /g, etc.), mixing with lithium-containing cathode active materials can improve the energy density of capacitors.
  • the conductive carbon black includes small particle conductive carbon black with a particle size of 10-200 nm and/or large particle conductive carbon black with a particle size of 1-30 ⁇ m, for example, the particle size of the small particle conductive carbon black can be 10nm, 15nm, 20nm, 50nm, 80nm, 100nm, 120nm, 150nm, 180nm, 190nm or 200nm, etc.; the particle size of large particle conductive carbon black can be 1 ⁇ m, 3 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 28 ⁇ m or 30 ⁇ m Wait.
  • the graphene-based material includes any one or a combination of at least two of graphene, graphene oxide, and doped graphene.
  • the one-dimensional carbon material includes carbon nanotubes and/or carbon fibers.
  • the second conductive agent includes at least one of graphene-based materials and at least one of one-dimensional carbon materials.
  • the mass ratio of the graphene-based material and the one-dimensional carbon material is (1-2): (3-6), and a super conductive network is formed in the positive electrode material layer under this optional ratio.
  • the mass ratio can be, for example, 1:3, 1:4, 1:5, 1:6, 2:3, 2:5 or 2:6, etc. If the mass ratio is less than 1 : 6, it is difficult to construct a three-dimensional conductive network for the positive electrode; if the mass ratio is greater than 2:3, the dispersion of graphene-like materials is difficult, and the internal resistance of the device increases.
  • the graphene-based material can be a component of the second conductive agent or a component of the carbon-based positive electrode active material, as long as it is located in the positive electrode material layer, it is included in the above content range.
  • the first binder and the second binder are fusible fluorocarbon resins.
  • the first binder and the second binder are independently selected from any one or a combination of at least two of PVDF, PTFE or PFA, wherein a typical but non-limiting combination: PVDF and PFA, PFA and PTFE.
  • the lithium-rich compound includes any one or at least two of Li 2 NiO 2 , Li 5 FeO 4 , Li 3 N, Li 2 O, Li 2 O 2 or M/lithium fluoride composite A combination, wherein M includes any one or a combination of at least two of Co, Ni or Fe, and can be selected to be any one or at least two of Li 2 NiO 2 , Li 3 N or M/lithium fluoride composite combination of species.
  • Li 2 NiO 2 and Li 5 FeO 4 Li 3 N and Li 2 O, Li 2 O and Li 2 O 2 , Li 3 N, Li 2 O and Li 2 O 2 , Li 2 Any one or a combination of at least two of NiO 2 and Ni/lithium fluoride complexes, Li 2 NiO 2 , Li 3 N or M/lithium fluoride complexes.
  • the "M/lithium fluoride complex” is a complex of metal M and lithium fluoride.
  • the binder further includes a third conductive agent, and the third conductive agent can be selected as conductive carbon black.
  • the total mass fraction of the first binder and the second binder is 2-10%, for example, 2%, 3% %, 5%, 6%, 8% or 10% etc.
  • the mass fraction of the first conductive agent is 1-6%, such as 1%, 2%, 3%, 4%, 5% or 6% etc.
  • the total mass fraction of the graphene-based material and the one-dimensional carbon material is 0.5-3%, such as 0.5%, 1%, 2%, 2.5% or 3% etc. If the mass is lower than 0.5%, the low temperature rate performance of the device is affected; if the mass is higher than 3%, the internal resistance of the device is increased, and the electrical performance is affected. It is easy to understand that the graphene-based material can be a component of the second conductive agent or a component of the carbon-based positive electrode active material, as long as it is located in the positive electrode material layer, it is included in the above content range.
  • the mass ratio of the third conductive agent to the first binder is (1-5):1, such as 1:1, 2:1, 3:1, 4:1 or 5:1 etc., optional (2-4):1.
  • the mass fraction of the lithium-containing positive electrode active material is 5-80%, for example, it can be 5%, 10%, 15%, 20% , 30%, 40%, 50%, 60%, 70% or 80% etc.
  • the mass fraction of the carbon-based positive electrode active material is 10-90%, for example, it can be 10%, 20%, 25%, 30% , 40%, 50%, 60%, 70%, 80% or 90% etc.
  • the mass fraction of the positive electrode active material is 85%-95%, such as 85%, 88%, 90%, 92%, 93% or 95% etc.
  • the mass ratio of the lithium-containing positive electrode active material and the carbon-based positive electrode active material is 1:(0.5-1.5), such as 1:0.5, 1:0.8, 1:0.9, 1:1, 1:1.2, 1:1.3 or 1:1.5, etc., optional 1:(1-1.2).
  • the mass fraction of the lithium-rich compound is 2-30%, for example, it can be 2%, 3%, 5%, 10%, 15% , 20%, 25% or 30% etc. If the mass is less than 2%, the capacity and the median discharge voltage of the device are low; if the mass is higher than 30%, the cost of the raw materials of the device increases.
  • the present application provides a method for preparing a positive electrode as described in the above-mentioned first aspect, comprising the following steps:
  • the conductive agent includes a first conductive agent and a second conductive agent
  • the first conductive agent includes graphite
  • the second conductive agent includes at least one of graphene-based materials and one-dimensional carbon materials
  • step (2) coating the surface of the current collector with a dispersion liquid containing a first binder, performing first baking to prepare a bonding layer, and then coating the positive electrode slurry obtained in step (1) on the bonding
  • the surface of the layer is baked for the second time to obtain an intermediate product
  • step (3) rolling the intermediate product obtained in step (2) and baking for the third time to obtain the positive electrode.
  • the preparation method provided in the present application by coating the surface of the positive electrode current collector with a dispersion liquid containing a first binder, and then rolling and baking, the combination of the positive electrode materials and the current collector is made closer, the internal resistance of the electrode sheet is reduced, and the improvement of High-power charge-discharge performance; the first conductive agent and the second conductive agent can build a three-dimensional conductive network; the lithium-rich oxide and the positive active material provide lithium ions to enter the negative electrode during the charging process, and perform lithium intercalation behavior, so that the negative electrode can be exempted from The pre-lithiation step simplifies the process, reduces the production cost, and has high application value.
  • step (1) The application does not specifically limit the mixing method of the positive electrode slurry in step (1), which can be one-step mixing or step-by-step mixing, for example, it can be divided into two steps, three steps, and four steps, etc. Preparation is required.
  • dry-mixing gaseous substances other than the graphene-based material to obtain a mixed powder then mixing the graphene-based material with the mixed powder, and finally adding an organic solvent and mixing to obtain a positive electrode slurry.
  • organic solvent is not specifically limited, as long as it is an organic solvent commonly used by those skilled in the art, it is applicable to this application.
  • the current collector in step (2) includes any one of a corroded current collector, a coated current collector, a pure current collector or a through-hole current collector.
  • the mass fraction of the binder is 1-10%, such as 1%, 3%, 5%, 8%, 9% or 10%, etc. 2-8%.
  • the dispersion liquid described in step (2) further includes a third conductive agent.
  • the temperature of the first baking in step (2) is 60-180°C, such as 60°C, 70°C, 75°C, 80°C, 85°C, 90°C, 100°C, 120°C, 140°C °C, 160 °C, 170 °C or 180 °C, etc., optional 80-150 °C; if the temperature is lower than 60 °C, the organic solvent cannot be dried; if the temperature is higher than 180 °C, the pole piece may crack.
  • the thickness of the adhesive layer in step (2) is 0.5-10 ⁇ m, for example, it can be 0.5 ⁇ m, 1 ⁇ m, 2 ⁇ m, 4 ⁇ m, 6 ⁇ m, 8 ⁇ m, 9 ⁇ m or 10 ⁇ m, etc., and can be 1-5 ⁇ m; If the thickness is less than 0.5 ⁇ m, the adhesion of the conductive adhesive layer to the powder is too small, which cannot effectively reduce the resistance of the pole piece and prevent the powder from falling off; if the thickness is greater than 10 ⁇ m, the thickness of the pole piece is too large, which is not conducive to improving the energy density of the device.
  • the temperature of the second baking in step (2) is 80-150°C, such as 80°C, 85°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, etc., optional 100-130°C; if the temperature is lower than 80°C, the residual solvent and moisture of the pole piece cannot be taken away; if the temperature is higher than 150°C, the pole piece is over-baked and may fall off powder.
  • the temperature of the environment is controlled to be 20-30°C, and the humidity is 3-40%, for example, the temperature can be 20°C, 22°C, 25°C, 26°C, 28°C or 30°C. °C, etc., the humidity can be 3%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35% or 40%, etc.
  • the rolling speed of step (3) is 2-50m/min, such as 2m/min, 5m/min, 10m/min, 20m/min, 25m/min, 30m/min, 35m/min min, 40m/min, 45m/min, 48m/min or 50m/min, etc. If the speed is less than 2m/min, the production efficiency of the pole piece is low; if the speed is greater than 50m/min, the adhesive layer and the slurry cannot be well material bonding.
  • the rolling method in step (3) is cold pressing and/or hot pressing.
  • the temperature of the cold pressing is 0-45°C, for example, 0°C, 5°C, 10°C, 15°C, 20°C, 30°C, 40°C or 45°C, etc.
  • the temperature of the hot pressing is 60-270°C, such as 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 160°C, 180°C °C, 190 °C, 200 °C, 230 °C, 250 °C or 270 °C, etc., optional 80-250 °C; the temperature is lower than 60 °C, the adhesive in the hot-melt adhesive layer cannot be hot-melted, which is not conducive to the production of stickiness. Bonding force; when the temperature is higher than 270°C, the structure of the adhesive may be damaged.
  • the manner of the third baking in step (3) includes vacuum baking.
  • the vacuum degree of the vacuum baking is 5-200Pa, such as 5Pa, 10Pa, 15Pa, 20Pa, 50Pa, 80Pa, 100Pa, 150Pa, 180Pa or 200Pa, etc.
  • the temperature of the third baking in step (3) is 80-150°C, such as 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 135°C, 140°C, 145°C or 150°C, etc.
  • the time of the third baking in step (3) is 10-60min, for example, it can be 10min, 10min, 20min, 30min, 40min, 50min or 60min, etc.
  • the preparation method comprises the following steps:
  • the intermediate product obtained in the step (2) is controlled at a rolling speed of 2-50m/s, hot-pressed at a temperature of 60-270°C, and baked at a temperature of 80-150°C and a vacuum degree of 5-200Pa. 10-60min to obtain the positive electrode;
  • step (1) and step (2) are performed in an environment with a temperature of 20-30° C. and a humidity of 3-40%.
  • the present application further provides a hybrid capacitor, the hybrid capacitor comprising the positive electrode as described in the first aspect.
  • the hybrid capacitor provided by the present application adopts the positive electrode as described in the first aspect above.
  • the positive electrode includes a current collector, a bonding layer and a positive electrode material layer sequentially located on the surface of the current collector, a lithium-rich compound in the positive electrode material layer and a positive electrode.
  • the active material can extract lithium ions into the negative electrode during the charging process, so that the negative electrode can be free from pre-intercalation of lithium, so that the manufacturing process of the hybrid capacitor is simple and the cost is low; at the same time, the energy density and rate performance are improved, which can meet the needs of the Internet of Things power supply.
  • the present application provides a positive electrode, comprising a current collector, a bonding layer and a positive electrode material layer sequentially located on the surface of the current collector, the bonding layer improves the binding ability of the current collector and the positive electrode material layer, reduces the internal resistance of the electrode sheet, and the positive electrode
  • the conductive agent, lithium-rich compound and positive active material in the material layer cooperate with each other to improve the energy density and rate performance of the positive electrode, and at the same time provide lithium ions to enter the negative electrode during the charging process to realize the pre-lithiation-free of the negative electrode;
  • the surface of the positive electrode current collector is coated with a dispersion liquid containing a first binder, and then rolled and baked to make the combination of the positive electrode materials and the current collector more closely, reducing the polarity of the positive electrode.
  • On-chip resistance improves high-power charge-discharge performance; the first conductive agent and the second conductive agent build a three-dimensional conductive network; the lithium-rich compound and the positive active material provide lithium ions into the negative electrode during the charging process, and perform lithium intercalation behavior, making the negative electrode It can be exempted from pre-lithiation, simplify the process, reduce the production cost, and be easy to industrialize;
  • the hybrid capacitor provided by the present application adopts a positive electrode including a current collector, and a bonding layer and a positive electrode material layer sequentially located on the surface of the current collector, so that the energy density of the capacitor is improved, the rate performance is improved, and the negative electrode is free of charge.
  • the types of current collectors are not limited in the embodiments of the present application, and may be etched current collectors, coated current collectors, pure current collectors or through-hole current collectors, etc.
  • the corrosion current collector is etched aluminum foil, which may be commercially available or It is prepared by corroding aluminum foil.
  • the specific method for corroding aluminum foil is the prior art, and those skilled in the art can refer to the method disclosed in the prior art for preparation; the coating current collector is carbon-coated aluminum foil.
  • This embodiment provides a positive electrode for a hybrid capacitor, the positive electrode includes a current collector, a bonding layer and a positive electrode material layer sequentially located on the surface of the current collector; the bonding layer is composed of a first binder (specifically composed of: PTFE, with a thickness of 1 ⁇ m), the positive electrode material layer includes a second binder (specifically composed of PVDF), a conductive agent, a positive electrode active material and a lithium-rich compound, and the conductive agent includes a first conductive agent and a second conductive agent.
  • a first binder specifically composed of: PTFE, with a thickness of 1 ⁇ m
  • the positive electrode material layer includes a second binder (specifically composed of PVDF)
  • a conductive agent includes a first conductive agent and a second conductive agent.
  • the first conductive agent is graphite powder
  • the second conductive agent is a mixture of graphene and carbon nanotubes in a mass ratio of 1:4
  • the positive active material is a mixture of activated carbon and lithium cobalt oxide
  • the lithium-rich compound is Li 2 NiO 2 ;
  • the total mass fraction of the first binder and the second binder is 5wt%; the mass fraction of the first conductive agent is 4%, the second The mass fraction of conductive agent is 1%; the mass fraction of lithium cobalt oxide is 45wt%, the mass fraction of activated carbon is 40wt%, and the mass fraction of lithium-rich compound is 5%.
  • the present embodiment provides a method for preparing the positive electrode of the above-mentioned hybrid capacitor, comprising the following steps:
  • step (1) Coat the surface of the current collector with a PTFE dispersion with a mass fraction of 3%, bake at 90° C. to prepare a conductive adhesive layer, control the thickness of the adhesive layer to be 1 ⁇ m, and then add the obtained in step (1).
  • the positive electrode slurry is coated on the surface of the bonding layer and baked at 85°C to obtain an intermediate product;
  • the intermediate product obtained in the step (2) is controlled at a rolling speed of 2 m/min, and the temperature is 140 ° C for hot pressing, and at 140 ° C, under the condition of a vacuum degree of 5Pa, bake for 30 min to obtain the positive electrode. ;
  • step (1) and step (2) are carried out at an ambient temperature of 25° C. and a humidity of 5%.
  • This embodiment provides a positive electrode for a hybrid capacitor, the positive electrode includes a current collector, a bonding layer and a positive electrode material layer sequentially located on the surface of the current collector; the bonding layer is composed of a first binder (specifically composed of: PVDF, with a thickness of 0.5 ⁇ m), the positive electrode material layer includes a second binder (specifically composed of PTFE), a conductive agent, a positive electrode active material and a lithium-rich compound, and the conductive agent includes a first conductive agent and a second conductive agent.
  • a first binder specifically composed of: PVDF, with a thickness of 0.5 ⁇ m
  • the positive electrode material layer includes a second binder (specifically composed of PTFE)
  • a conductive agent includes a first conductive agent and a second conductive agent.
  • the first conductive agent is acetylene black
  • the second conductive agent is a mixture of graphene oxide and carbon nanotubes in a mass ratio of 2:3
  • the positive active material is a mixture of graphene and lithium manganate
  • the lithium-rich compound is Li3N ;
  • the total mass fraction of the first binder and the second binder is 2wt%; the mass fraction of the first conductive agent is 1%, the second The mass fraction of conductive agent is 0.5%; the mass fraction of lithium manganate is 84.5 wt%, the mass fraction of graphene is 10 wt%; the mass fraction of lithium-rich compound is 2%.
  • the present embodiment provides a method for preparing a positive electrode of a hybrid capacitor, comprising the following steps:
  • step (1) Coating the PVDF dispersion with a mass fraction of 8% on the surface of the current collector, baking at 60° C. to prepare a bonding layer, and controlling the thickness of the bonding layer to be 0.5 ⁇ m, and then adding the obtained in step (1)
  • the positive electrode slurry is coated on the surface of the bonding layer and baked at 80°C to obtain an intermediate product;
  • step (1) and step (2) are carried out at an ambient temperature of 20° C. and a humidity of 3%.
  • the positive electrode for a hybrid capacitor
  • the positive electrode includes a current collector, a bonding layer and a positive electrode material layer sequentially located on the surface of the current collector;
  • the bonding layer is composed of a first binder (specifically composed of: PFA, with a thickness of 5 ⁇ m)
  • the positive electrode material layer includes a second binder (specifically composed of PFA), a conductive agent, a positive electrode active material and a lithium-rich compound
  • the conductive agent includes a first conductive agent and a second conductive agent
  • the first conductive agent is SP
  • the second conductive agent is a mixture of graphene and carbon nanotubes in a mass ratio of 2:4
  • the positive active material is a mixture of activated carbon and NCM811
  • the lithium-rich compound is Li 2 O;
  • the total mass fraction of the first binder and the second binder is 5wt%; the mass fraction of the first conductive agent is 3%, the second The mass fraction of conductive agent is 1.5%; the mass fraction of NCM811 is 35wt%, the mass fraction of activated carbon is 45wt%, and the mass fraction of lithium-rich compound is 10.5%.
  • the present embodiment provides a method for preparing the positive electrode of the above-mentioned hybrid capacitor, comprising the following steps:
  • step (1) and step (2) are carried out at an ambient temperature of 25° C. and a humidity of 5%.
  • This embodiment provides a positive electrode of a hybrid capacitor, the positive electrode includes a current collector, and an adhesive layer and a positive electrode material layer sequentially located on the surface of the current collector; the adhesive layer includes a first binder and a third conductive agent ( Specifically, the first binder is composed of PTFE, the third conductive agent is SP, and the thickness is 3 ⁇ m), and the positive electrode material layer includes a second binder (specifically composed of PVDF), conductive agent, positive electrode active material and Lithium-rich compound, the conductive agent includes a first conductive agent and a second conductive agent, the first conductive agent is acetylene black, and the second conductive agent is a mixture of graphene and carbon nanotubes in a mass ratio of 1:6; The substance is a mixture of porous biomass carbon and LiNi 0.85 Al 0.075 Mn 0.075 O 2 ; the lithium-rich compound is a Co/lithium fluoride complex;
  • the total mass fraction of the first binder and the second binder is 5wt%; the mass fraction of the first conductive agent is 2%, the second The mass fraction of the conductive agent is 2%, the mass fraction of the third conductive agent is 6%; the mass fraction of LiNi 0.85 Al 0.075 Mn 0.075 O 2 is 50 wt %, the mass fraction of porous biomass carbon is 10 wt %, and the mass fraction of the lithium-rich compound is 10 wt %.
  • the score is 25%.
  • the present embodiment provides a method for preparing the positive electrode of the above-mentioned hybrid capacitor, comprising the following steps:
  • step (1) Coat the surface of the current collector with a dispersion of 3% PTFE and acetylene black, bake at 180° C. to prepare an adhesive layer, and control the thickness of the adhesive layer to be 3 ⁇ m, and then step (1)
  • the positive electrode slurry obtained in the process is coated on the surface of the bonding layer, and baked at 150 ° C to obtain an intermediate product;
  • step (1) and step (2) are carried out at an ambient temperature of 30° C. and a humidity of 40%.
  • This embodiment provides a positive electrode of a hybrid capacitor, the positive electrode includes a current collector, and an adhesive layer and a positive electrode material layer sequentially located on the surface of the current collector; the adhesive layer includes a first binder and a third conductive agent ( Specifically, the first binder is composed of PTFE, the third conductive agent is SP, and the thickness is 4 ⁇ m), and the positive electrode material layer includes a second binder (specifically composed of PVDF), conductive agent, positive electrode active material and Lithium-rich compound, the conductive agent includes a first conductive agent and a second conductive agent, the first conductive agent is SP, the second conductive agent is a mixture of graphene and carbon nanotubes in a mass ratio of 2:5, and the third conductive agent is The agent is SP; the positive active material is a mixture of porous biomass carbon and LiNi 0.85 Al 0.075 Mn 0.075 O 2 ; the lithium-rich compound is Ni/lithium fluoride composite;
  • the total mass fraction of the first binder and the second binder is 3 wt% based on the total mass of the bonding layer and the positive electrode material layer as 100%; the mass fraction of the first conductive agent is 1%, the second The mass fraction of the conductive agent is 1%, the mass fraction of the third conductive agent is 5%; the mass fraction of LiNi 0.85 Al 0.075 Mn 0.075 O 2 is 5 wt %, the mass fraction of porous biomass carbon is 87 wt %, and the lithium-rich compound has a mass fraction of 87 wt %.
  • the mass fraction is 3%.
  • the present embodiment provides a method for preparing the positive electrode of the above-mentioned hybrid capacitor, comprising the following steps:
  • step (1) Coat the surface of the current collector with a dispersion liquid of PTFE and SP with a mass fraction of 1%, bake at 180° C. to prepare an adhesive layer, and control the thickness of the adhesive layer to be 10 ⁇ m, and then add the step (1) in step (1).
  • the obtained positive electrode slurry is coated on the surface of the adhesive layer, and baked at 150° C. to obtain an intermediate product;
  • step (1) and step (2) are carried out at an ambient temperature of 30° C. and a humidity of 40%.
  • Example 1 Compared with Example 1, the only difference is that the hot pressing in step (3) is replaced by cold pressing at 5°C.
  • Example 1 Compared with Example 1, the only difference is that the hot pressing in step (3) is replaced by cold pressing at 40°C.
  • Example 1 Compared with Example 1, the only difference is that the total mass ratio of lithium cobalt oxide and activated carbon is the same as that of Example 1, which is 85%, and the mass ratio of lithium cobalt oxide to activated carbon is 2.5:1.
  • Example 1 Compared with Example 1, the only difference is that compared with Example 1, the only difference is that compared with Example 1, the only difference is that the total mass ratio of lithium cobalt oxide and activated carbon is the same as that of Example 1, which is 85%, and the ratio of lithium cobalt oxide to activated carbon is 85%. The mass ratio is 2:8.
  • Example 1 Compared with Example 1, the only difference is that the lithium-rich compound Li 2 NiO 2 is not added in the method for preparing the positive electrode provided by this comparative example, and the mass ratio of the remaining substances in the positive electrode material layer is kept unchanged.
  • Example 1 Compared with Example 1, the only difference is that in the preparation method of the positive electrode provided in this comparative example, no activated carbon is added, but an equivalent amount of lithium cobalt oxide is used instead.
  • Example 1 Compared with Example 1, the only difference is that in the preparation method of the positive electrode provided by this comparative example, the mixture of graphene and carbon nanotubes is not added, but replaced with an equivalent amount of graphite powder.
  • Example 1 Compared with Example 1, the difference is that no binder layer is provided, and the content of binder in the positive electrode material layer is kept the same as the total amount of the first binder and the second binder in Example 1.
  • the positive electrode of the hybrid capacitor is prepared from the above embodiment and the comparative example, and the capacitor is assembled with the graphite negative electrode, and the capacity, room temperature rate and -40 °C low temperature test are carried out.
  • the test method is as follows:
  • Capacity test put the hybrid capacitor in the environment of 25°C, put it on hold for 5min, charge it to 3.9V with 5mA constant current and constant voltage, and the cut-off current is 0.5mA; put it on hold for 5min, discharge it to 2.2V with 5mA constant current, and finish.
  • Rate test put the hybrid capacitor in the environment of 25°C, charge the new Wei 5V5A precision discharge cabinet with 5mA constant current and constant voltage to 3.68V, cut-off current 0.5mA; leave it for 5min, 500C rate, pulse discharge for 1s, record the lowest voltage, and end.
  • -40°C low temperature test put the hybrid capacitor in the environment of 25°C, charge the 5V5A precision discharge cabinet with 5mA constant current and constant voltage to 3.68V, and the cut-off current is 0.5mA; transfer the hybrid capacitor to the high and low temperature box at -40°C for 6 hours, 150C rate pulse for 0.1s, record the lowest voltage, end.
  • the batteries prepared in the examples and comparative examples of the present application are of the same model (15500), and the higher the capacity, the higher the energy density.
  • the voltage of 25°C&500C represents the lowest voltage tested under the condition of 25°C and the current of 500C
  • the voltage of -40°C&150C represents the lowest voltage of the test under the condition of -40°C and the current of 150C.
  • Example 1 Combining Example 1 and Comparative Example 1 , it can be seen that the positive electrode of Comparative Example 1 does not contain Li 2 NiO 2 , and the capacity and rate performance are both reduced. Energy density, room temperature rate capability, and low temperature rate capability of hybrid capacitors.
  • Example 1 It can be seen from Example 1, Example 8 and Example 9 that the addition amount of lithium-containing positive electrode active material and carbon-based active material has an important influence on the capacity and rate performance of the material, and the lithium-containing positive electrode active material and carbon
  • the mass ratio of the positive electrode-like active material is in the optional range of 1:(0.5-1.5)
  • the effects of the above two aspects can be better balanced.
  • the present application illustrates the detailed structural features of the present application through the above-mentioned embodiments, but the present application is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present application must rely on the above-mentioned detailed structural features to be implemented.

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Abstract

本文涉及一种混合电容器的正极及其制备方法和用途，所述正极包括集流体，以及依次位于集流体表面的粘结层和正极材料层，粘结层包括第一粘结剂，正极材料层中包括第二粘结剂、导电剂、正极活性物质和富锂化合物，导电剂中包括第一导电剂和第二导电剂，第一导电剂包括石墨粉、导电碳黑或乙炔黑中的至少一种，第二导电剂包括石墨烯类材料以及一维碳材料中的至少一种。

Description

一种混合电容器的正极及其制备方法和用途 技术领域
本申请属于混合电容器技术领域，涉及一种混合电容器的正极及其制备方法和用途。
背景技术
随着能源与环境问题的日益突出，清洁能源和可再生能源受到广泛的研究与利用。超级电容器作为一种介于常规电容器和二次电池之间的新型高效储能元件得到关注与研究。其中，碳基超级电容器以碳材料作为主要电极材料，受到广泛的使用，活性炭是常用的碳材料之一，但是活性炭的比电容一般在25-35F/g之间，压实密度仅为0.5-0.6g/m 2，采用纯活性炭为电极的电容器能量密度只有2-10Wh/kg，受到严重的限制。此外，活性炭电极主要通过制成水系浆料涂覆于箔材表面烘干辊压获得，因活性炭具有极强的吸附能力，残留的水分很难烘干，进而影响器件的电压和放电性能。因此，人们将研究重点转移到了混合电容器，其中，锂离子电容器具有能量密度和功率密度高、静电容量高和循环寿命比锂离子电池更长的优点，有望在新能源汽车、风能和物联网等领域得到广泛的应用。
目前，为了获得高能量密度和提高负极电位，锂离子电容器负极普遍需要进行预嵌锂处理。CN104538194A公开了一种采用预锂化硬炭负极的锂离子电容器(LIC)的制备方法，以商品化的活性炭为正极、硬炭为负极，1M的LiPF 6/EC+DEC为电解液组装锂离子电容器。嵌锂容量为400mAh/g的LIC，最高能量密度和功率密度分别为76.5Wh/kg和5.1kW/kg，且循环1000次后，能量保持率仍高达92.0％。经过15h预锂化的锂离子电容器能量密度可达97.2Wh/kg， 具有最小的阻抗和良好的循环性能(1A/g的电流密度下循环1000次后，能量保持率为91.2％)。当正负极质量配比为2.2时，能量保持率为57.0％。同时，电容器具有非常小的电荷转移内阻(10.4)，最大能量密度和功率密度分别为88.7Wh/kg和12kW/kg。但是该发明提供的制备方法工艺较复杂、时间长、成本高，且无法满足物联网电源对倍率性能和能量密度的要求。
CN104617335A公开了一种低温化学电源及其制造方法，制造方法包括如下步骤：1)制备电芯，并焊接极耳将电芯入壳封装完成后进行干燥；2)将电芯入壳封装完成后进行干燥，并完成一次注液；3)对锂离子电容器或锂离子电池进行化成处理；4)将化成完成的单体进行第二次注液；5)对单体进行整型，进行后续处理。该发明取两次注液，第一次注液目的主要是化成成膜，第二次注液的目的是提高器件的电导率和低温特性。该发明尽管改善了化学电源的低温性能，但是仍然不能满足物联网电源对工作温度-40℃-125℃的需求。
基于上述文献的研究，如何开发一种满足物联网电源应用，能量密度高、倍率性能好、负极免预锂和成本较低的混合电容器，成为亟待解决的问题。
发明内容
本申请的目的在于提供一种混合电容器的正极及其制备方法和用途。所述混合电容器的正极，通过对常规正极配方和工艺改进，解决了碳基电容器能量密度偏低和负极需要预嵌锂处理的问题，提升器件的能量密度和倍率性能，能够满足-40℃-125℃大倍率脉冲放电。本申请的方法尤其适合提高室温倍率性能和低温倍率性能，同时实现负极免预锂，降低生产成本。
为达此目的，本申请采用以下技术方案：
第一方面，本申请提供一种混合电容器用正极，所述正极包括集流体，以 及依次位于集流体表面的粘结层和正极材料层，所述粘结层包括第一粘结剂，所述正极材料层中包括第二粘结剂、导电剂、正极活性物质和富锂化合物。
本申请提供的正极通过在集流体与正极材料层之间设置粘结层，提高了正极材料与集流体的结合能力，降低极片内阻；富锂化合物和正极活性物质在充电过程中提供锂离子进入负极，进行嵌锂行为，使得负极可免于预锂化步骤；上述各物质相互作用，提升了正极的倍率性能，能够满足大倍率充放电的需求。
可选地，所述粘结层的厚度为0.5-10μm，例如可以是0.5μm、1μm、2μm、4μm、6μm、8μm、9μm或10μm等，可选为1-5μm。所述厚度小于0.5μm，则导电粘结层对粉料的粘结力偏小，不能有效减小极片电阻和防止粉料脱落；厚度大于10μm，则极片厚度偏大，不利于提升器件能量密度。
可选地，所述导电剂中包括第一导电剂和第二导电剂，所述第一导电剂包括石墨粉、导电碳黑或乙炔黑中的至少一种，所述第二导电剂包括石墨烯类材料以及一维碳材料中的至少一种。正极材料层中，石墨烯类材料和/或一维碳材料构建三维立体导电网络，石墨粉、导电碳黑或乙炔黑中的至少一种粒子分散在导电网络的内部和/或表面，形成完善的导电体系，提升材料的电导率。
可选地，所述正极活性物质包括含锂正极活性物质和碳类正极活性物质。
可选地，所述含锂正极活性物质包括钴酸锂、镍酸锂、锰酸锂、磷酸亚铁锂、镍钴锰三元材料、镍钴铝三元材料或镍钴锰铝四元材料中的任意一种或至少两种的组合，可选为镍酸锂、镍钴锰三元材料、镍钴铝三元材料或镍钴锰铝四元材料中的任意一种或至少两种的组合。其中典型但非限制性组合：钴酸锂和锰酸锂，锰酸锂和磷酸铁锂，磷酸铁锂和钴酸锂，镍钴锰三元材料和镍钴铝三元材料，镍钴铝三元材料和镍钴锰铝四元材料，可选为镍酸锂、镍钴锰三元 材料、镍钴铝三元材料或镍钴锰铝四元材料中的任意一种或至少两种的组合。
可选地，所述碳类正极活性物质包括活性炭、石墨烯、掺杂石墨烯或多孔生物质碳中的任意一种或至少两种的组合。
本申请中，所述碳类正极活性物质具有较大的比表面积，一般在1500m 2/g以上(例如1500m 2/g、1600m 2/g、1700m 2/g、1800m 2/g、2000m 2/g或2100m 2/g等)，与含锂正极活性物质混合可实现电容器能量密度的提升。
可选地，所述导电碳黑包括粒径为10-200nm的小颗粒导电碳黑和/或粒径为1-30μm的大颗粒导电碳黑，例如，小颗粒导电碳黑的粒径可以是10nm、15nm、20nm、50nm、80nm、100nm、120nm、150nm、180nm、190nm或200nm等；大颗粒导电碳黑的粒径可以是1μm、3μm、5μm、10μm、15μm、20μm、25μm、28μm或30μm等。
本申请中，对小颗粒导电碳黑或大颗粒导电碳黑的种类，不做具体的限定，可以是SP，只要是本领域技术人员常用的物质，均适用于本申请。
本申请中，所述石墨烯类材料包括石墨烯、氧化石墨烯、掺杂石墨烯中的任意一种或至少两种的组合。
可选地，所述一维碳材料包括碳纳米管和/或碳纤维。
可选地，所述第二导电剂包括石墨烯类材料中的至少一种以及一维碳材料中的至少一种。
可选地，所述正极材料层中，石墨烯类材料和一维碳材料的质量比为(1-2):(3-6)，在此可选比率下正极材料层内形成超级导电网络进而获得优异的电导率，所述质量比例如可以是1:3、1:4、1:5、1:6、2:3、2:5或2:6等，若所述质量比小于1:6，正极构建三维导电网络困难；质量比大于2:3，石墨烯类材料 的分散困难，器件内阻增大。容易理解的是，石墨烯类材料可以是第二导电剂的组成部分，也可以是碳类正极活性物质的组成部分，只要是位于正极材料层中，即计入上述的含量范围内。
可选地，所述第一粘结剂和第二粘结剂为可熔性氟碳树脂。
可选地，所述第一粘结剂和第二粘结剂独立地选自PVDF、PTFE或PFA中的任意一种或至少两种的组合，其中典型但非限制性组合：PVDF和PFA，PFA和PTFE。
可选地，所述富锂化合物包括Li 2NiO 2、Li 5FeO 4、Li 3N、Li 2O、Li 2O 2或M/氟化锂复合物中的任意一种或至少两种的组合，其中，M包括Co、Ni或Fe中的任意一种或至少两种的组合，可选为Li 2NiO 2、Li 3N或M/氟化锂复合物中的任意一种或至少两种的组合。其中典型但非限制性组合：Li 2NiO 2和Li 5FeO 4，Li 3N和Li 2O，Li 2O和Li 2O 2，Li 3N、Li 2O和Li 2O 2，Li 2NiO 2和Ni/氟化锂复合物，Li 2NiO 2、Li 3N或M/氟化锂复合物中的任意一种或至少两种的组合。
所述“M/氟化锂复合物”为金属M和氟化锂的复合物。
作为本申请所述正极的可选技术方案，所述粘结剂中还包括第三导电剂，所述第三导电剂可选为导电碳黑。
可选地，以粘结层和正极材料层的总质量为100％计，所述第一粘结剂和第二粘结剂的总质量分数为2-10％，例如可以是2％、3％、5％、6％、8％或10％等。
对于第一粘结剂和第二粘结剂的配比无特定限定，本领域技术人员可根据需要进行选择。
可选地，以粘结层和正极材料层的总质量为100％计，所述第一导电剂的质 量分数为1-6％，例如可以是1％、2％、3％、4％、5％或6％等。
可选地，以粘结层和正极材料层的总质量为100％计，所述石墨烯类材料和一维碳材料的总质量分数为0.5-3％，例如可以是0.5％、1％、2％、2.5％或3％等。若所述质量低于0.5％，器件的低温倍率性能受影响；质量高于3％，器件的内阻增大，电性能受影响。容易理解的是，石墨烯类材料可以是第二导电剂的组成部分，也可以是碳类正极活性物质的组成部分，只要是位于正极材料层中，即计入上述的含量范围内。
可选地，所述第三导电剂与第一粘结剂的质量比为(1-5):1，例如可以是1:1、2:1、3:1、4:1或5:1等，可选为(2-4):1。
可选地，以粘结层和正极材料层的总质量为100％计，所述含锂正极活性物质的质量分数为5-80％，例如可以是5％、10％、15％、20％、30％、40％、50％、60％、70％或80％等。
可选地，以粘结层和正极材料层的总质量为100％计，所述碳类正极活性物质的质量分数为10-90％，例如可以是10％、20％、25％、30％、40％、50％、60％、70％、80％或90％等。
可选地，以粘结剂和正极材料层的总质量为100％计，所述正极活性物质的质量分数为85％-95％，例如85％、88％、90％、92％、93％或95％等。
可选地，所述含锂正极活性物质和碳类正极活性物质的质量比为1:(0.5-1.5)，例如1:0.5、1:0.8、1:0.9、1:1、1:1.2、1:1.3或1:1.5等，可选为1:(1-1.2)。
可选地，以粘结层和正极材料层的总质量为100％计，所述富锂化合物的质量分数2-30％，例如可以是2％、3％、5％、10％、15％、20％、25％或30％等。若所述质量低于2％，器件的容量和放电中值电压偏低；质量高于30％，器件原 材料成本增加。
第二方面，本申请提供如上述第一方面所述的正极的制备方法，包括以下步骤：
(1)将第二粘结剂、导电剂、正极活性物质和富锂化合物混合，得到正极浆料，所述导电剂包括第一导电剂和第二导电剂，所述第一导电剂包括石墨粉、导电碳黑或乙炔黑中的至少一种，所述第二导电剂包括石墨烯类材料以及一维碳材料中的至少一种；
(2)向集流体表面涂覆含有第一粘结剂的分散液，进行第一次烘烤，制备粘结层，再将步骤(1)中得到的正极浆料涂覆于所述粘结层表面，进行第二次烘烤，得到中间产品；
(3)将步骤(2)中得到的中间产品进行碾压，第三次烘烤，得到所述的正极。
本申请提供的制备方法，通过在正极集流体表面涂覆含有第一粘结剂的分散液，然后碾压、烘烤使得正极各物质与集流体的结合更紧密，降低极片内阻，提升大功率充放电性能；第一导电剂和第二导电剂可构建三维立体导电网络；富锂氧化物和正极活性物质在充电过程中提供锂离子进入负极，进行嵌锂行为，使得负极可免于预锂化步骤，简化工艺，降低生产成本，具有较高的应用价值。
本申请对步骤(1)所述正极浆料的混合方法不作具体限定，可以是一步混合，也可以是分步混合，例如可以分两步、三步和四步等，本领域技术人员可根据需要进行制备。
可选将石墨烯类材料以外的气体物质干混，得到混合粉末，然后将石墨烯类材料与所述混合粉末混合，最后加入有机溶剂混匀，得到正极浆料。
本申请中，对有机溶剂的种类不作具体限定，只要是本领域技术人员常用的有机溶剂均适用于本申请。
可选地，步骤(2)所述集流体包括腐蚀集流体、涂覆集流体、纯集流体或通孔集流体中的任意一种。
可选地，步骤(2)所述的分散液中，粘结剂的质量分数为1-10％，例如1％、3％、5％、8％、9％或10％等，可选为2-8％。
可选地，步骤(2)所述的分散液中，还包括第三导电剂。
可选地，步骤(2)所述第一次烘烤的温度为60-180℃，例如可以是60℃、70℃、75、80℃、85℃、90℃、100℃、120℃、140℃、160℃、170℃或180℃等，可选为80-150℃；所述温度低于60℃，不能将有机溶剂烘干；温度高于180℃，极片可能开裂。
可选地，步骤(2)所述粘结层的厚度为0.5-10μm，例如可以是0.5μm、1μm、2μm、4μm、6μm、8μm、9μm或10μm等，可选为1-5μm；所述厚度小于0.5μm，导电粘结层对粉料的粘结力偏小，不能有效减小极片电阻和防止粉料脱落；厚度大于10μm，则极片厚度偏大，不利于提升器件能量密度。
可选地，步骤(2)所述第二次烘烤的温度为80-150℃，例如可以是80℃、85℃、90℃、100℃、110℃、120℃、130℃、140℃或150℃等，可选为100-130℃；所述温度低于80℃，不能将极片残留的溶剂和水分带走；温度高于150℃，极片烘烤过度，可能掉粉。
可选地，步骤(1)和(2)过程中控制环境温度为20-30℃，湿度为3-40％，例如温度可以是20℃、22℃、25℃、26℃、28℃或30℃等，湿度可以是3％、5％、8％、10％、15％、20％、25％、30％、35％或40％等。
可选地，步骤(3)所述碾压的速率为2-50m/min，例如可以是2m/min、5m/min、10m/min、20m/min、25m/min、30m/min、35m/min、40m/min、45m/min、48m/min或50m/min等，若所述速度小于2m/min，极片生产效率低；速度大于50m/min，不能很好地将粘结层和浆料粘结。
可选地，步骤(3)所述碾压的方式为冷压和/或热压。
可选地，所述冷压的温度0-45℃，例如可以是0℃、5℃、10℃、15℃、20℃、30℃、40℃或45℃等。
可选地，所述热压的温度为60-270℃，例如可以是60℃、70℃、80℃、90℃、100℃、110℃、120℃、130℃、140℃、160℃、180℃、190℃、200℃、230℃、250℃或270℃等，可选为80-250℃；所述温度低于60℃，无法热熔粘结层中的粘结剂，不利于产生粘结力；温度高于270℃，粘结剂的结构可能被破坏。
可选地，步骤(3)所述第三次烘烤的方式包括真空烘烤。
可选地，所述真空烘烤的真空度为5-200Pa，例如可以是5Pa、10Pa、15Pa、20Pa、50Pa、80Pa、100Pa、150Pa、180Pa或200Pa等。
可选地，步骤(3)所述第三次烘烤的温度为80-150℃，例如可以是80℃、90℃、100℃、110℃、120℃、130℃、135℃、140℃、145℃或150℃等。
可选地，步骤(3)所述第三次烘烤的时间为10-60min，例如可以是10min、10min、20min、30min、40min、50min或60min等。
可选地，所述的制备方法包括以下步骤：
(1)将第一导电剂、第二粘结剂、第二导电剂、正极活性物质和富锂化合物干混1-3h后，加入0.5-3wt％的第三导电剂搅拌混合1-2h，然后加入有机溶剂搅拌4-6h，得到正极浆料；
(2)向集流体表面涂覆第一粘结剂的分散液，在60-180℃下烘烤，制备粘结层，控制所述粘结层的厚度为0.5-10μm，再将步骤(1)中得到的正极浆料涂覆于所述粘结层表面，在80-150℃下烘烤，得到中间产品；
(3)将步骤(2)中得到的中间产品控制辊压速度2-50m/s，温度60-270℃进行热压，在80-150℃，真空度为5-200Pa的条件下，烘烤10-60min，得到所述的正极；
其中，步骤(1)和步骤(2)均在温度为20-30℃，湿度为3-40％的环境下进行。
第三方面，本申请还提供一种混合电容器，所述混合电容器包括如上述第一方面所述的正极。
本申请提供的混合电容器，采用如上述第一方面所述的正极，所述正极包括集流体，以及依次位于集流体表面的粘结层和正极材料层，正极材料层中的富锂化合物和正极活性物质可在充电过程中锂离子脱出进入负极，实现负极免预嵌锂，使得所述混合电容器的制作工艺简单，成本较低；同时提高能量密度和倍率性能，能够满足物联网电源的需求。
与现有技术相比，本申请至少有以下有益效果：
(1)本申请提供一种正极，包括集流体，以及依次位于集流体表面的粘结层和正极材料层，粘结层提高集流体与正极材料层的结合能力，降低极片内阻，正极材料层中的导电剂、富锂化合物和正极活性物质等物质相互配合，提升了正极的能量密度和倍率性能，同时在充电过程中提供锂离子进入负极，实现负极的免预锂化；
(2)本申请提供的正极的制备方法，通过在正极集流体表面涂覆含有第一 粘结剂的分散液，然后碾压、烘烤使得正极各物质与集流体的结合更紧密，降低极片内阻，提升大功率充放电性能；第一导电剂和第二导电剂构建三维立体导电网络；富锂化合物和正极活性物质在充电过程中提供锂离子进入负极，进行嵌锂行为，使得负极可免于预锂化，简化工艺，降低生产升本，易于产业化；
(3)本申请提供的混合电容器，通过采用包括集流体，以及依次位于集流体表面的粘结层和正极材料层的正极，使得电容器的能量密度得到提高，倍率性能得到改善，同时实现负极免预锂，满足物联网电源的需求。
具体实施方式
下面通过具体实施方式来进一步说明，本申请为达成预定的技术效果所采取的技术手段，对本申请的具体实施方式详细说明如下。
本申请实施例对集流体的种类不作限定，可以是腐蚀集流体、涂覆集流体、纯集流体或通孔集流体等，其中，腐蚀集流体为腐蚀铝箔，可以是市售的，也可以是对铝箔进行腐蚀制得的，具体的对铝箔腐蚀的方法为现有技术，本领域技术人员可参照现有技术公开的方法进行制备；涂覆集流体为涂碳铝箔。
实施例1
本实施例提供一种混合电容器的正极，所述正极包括集流体、以及依次位于集流体表面的粘结层和正极材料层；所述粘结层的组成为第一粘结剂(具体组成为PTFE，厚度为1μm)，所述正极材料层中包括第二粘结剂(具体组成为PVDF)、导电剂、正极活性物质和富锂化合物，所述导电剂包括第一导电剂和第二导电剂，第一导电剂为石墨粉，第二导电剂为石墨烯和碳纳米管按质量比为1:4的混合物；正极活性物质为活性炭和钴酸锂的混合物；富锂化合物为Li 2NiO 2；
其中，以粘结层和正极材料层的总质量为100％计，第一粘结剂和第二粘结剂的总质量分数为5wt％；第一导电剂的质量分数为4％，第二导电剂的质量分数为1％；钴酸锂的质量分数为45wt％，活性炭的质量分数为40wt％，富锂化合物的质量分数为5％。
本实施例提供上述混合电容器的正极的制备方法，包括以下步骤：
(1)将石墨粉、PVDF、活性炭、钴酸锂和Li 2NiO 2干混3h后，加入石墨烯和碳纳米管的混合物，搅拌混合2h，然后加入NMP搅拌4h，得到正极浆料；
(2)向集流体表面涂覆质量分数为3％的PTFE分散液，在90℃下烘烤，制备导电粘结层，控制粘结层的厚度在1μm，再将步骤(1)中得到的正极浆料涂覆于所述粘结层表面，在85℃下烘烤，得到中间产品；
(3)将步骤(2)中得到的中间产品控制辊压速度2m/min，温度140℃进行热压，在140℃，在真空度为5Pa的条件下，烘烤30min，得到所述的正极；
其中，步骤(1)和步骤(2)均在环境温度为25℃，湿度为5％下进行。
实施例2
本实施例提供一种混合电容器的正极，所述正极包括集流体、以及依次位于集流体表面的粘结层和正极材料层；所述粘结层的组成为第一粘结剂(具体组成为PVDF，厚度为0.5μm)，所述正极材料层中包括第二粘结剂(具体组成为PTFE)、导电剂、正极活性物质和富锂化合物，所述导电剂包括第一导电剂和第二导电剂，第一导电剂为乙炔黑，第二导电剂为氧化石墨烯和碳纳米管按质量比为2:3的混合物；正极活性物质为石墨烯和锰酸锂的混合物；富锂化合物为Li 3N；
其中，以粘结层和正极材料层的总质量为100％计，第一粘结剂和第二粘结 剂的总质量分数为2wt％；第一导电剂的质量分数为1％，第二导电剂的质量分数为0.5％；锰酸锂的质量分数为84.5wt％，石墨烯的质量分数为10wt％；富锂化合物的质量分数为2％。
本实施例提供一种混合电容器正极的制备方法，包括以下步骤：
(1)将乙炔黑、PTFE、氧化石墨烯、锰酸锂和Li 3N干混1h后，加入石墨烯和碳纳米管的混合物，搅拌混合2h，然后加入NMP搅拌5h，得到正极浆料；
(2)向集流体表面涂覆质量分数为8％的PVDF分散液，在60℃下烘烤，制备粘结层，控制粘结层的厚度为0.5μm，再将步骤(1)中得到的正极浆料涂覆于所述粘结层表面，在80℃下烘烤，得到中间产品；
(3)将步骤(2)中得到的正极片控制辊压速度2m/min，温度90℃进行热压，在80℃，在真空度为200Pa的条件下，烘烤30min，得到所述的正极；
其中，步骤(1)和步骤(2)均在环境温度为20℃，湿度为3％下进行。
实施例3
本实施例提供一种混合电容器的正极，所述正极包括集流体、以及依次位于集流体表面的粘结层和正极材料层；所述粘结层的组成为第一粘结剂(具体组成为PFA，厚度为5μm)，所述正极材料层中包括第二粘结剂(具体组成为PFA)、导电剂、正极活性物质和富锂化合物，所述导电剂包括第一导电剂和第二导电剂，第一导电剂为SP，第二导电剂为石墨烯和碳纳米管按质量比为2:4的混合物；正极活性物质为活性炭和NCM811的混合物；富锂化合物为Li 2O；
其中，以粘结层和正极材料层的总质量为100％计，第一粘结剂和第二粘结剂的总质量分数为5wt％；第一导电剂的质量分数为3％，第二导电剂的质量分 数为1.5％；NCM811的质量分数为35wt％，活性炭的质量分数为45wt％，富锂化合物的质量分数为10.5％。
本实施例提供上述混合电容器的正极的制备方法，包括以下步骤：
(1)将SP、PFA、碳纤维、NCM811和Li 2O干混2h后，加入石墨烯和碳纳米管的混合物，搅拌混合3h，然后加入NMP搅拌5h，得到正极浆料；
(2)向集流体表面涂覆质量分数为4％的PFA分散液，在120℃下烘烤，制备粘结层，控制粘结层的厚度为5μm，再将步骤(1)中得到的正极浆料涂覆于所述粘结层表面，在120℃下烘烤，得到中间产品；
(3)将步骤(2)中得到的正极片控制辊压速度25m/min，温度150℃进行热压，在120℃，在真空度为100Pa的条件下，烘烤20min，得到所述的正极；
其中，步骤(1)和步骤(2)均在环境温度为25℃，湿度为5％下进行。
实施例4
本实施例提供一种混合电容器的正极，所述正极包括集流体、以及依次位于集流体表面的粘结层和正极材料层；所述粘结层包括第一粘结剂和第三导电剂(具体的，第一粘结剂组成为PTFE，第三导电剂为SP，厚度为3μm)，所述正极材料层中包括第二粘结剂(具体组成为PVDF)、导电剂、正极活性物质和富锂化合物，所述导电剂包括第一导电剂和第二导电剂，第一导电剂为乙炔黑，第二导电剂为石墨烯和碳纳米管按质量比为1:6的混合物；正极活性物质为多孔生物质碳和LiNi 0.85Al 0.075Mn 0.075O 2的混合物；富锂化合物为Co/氟化锂复合物；
其中，以粘结层和正极材料层的总质量为100％计，第一粘结剂和第二粘结剂的总质量分数为5wt％；第一导电剂的质量分数为2％，第二导电剂的质量分数为2％，第三导电剂质量分数为6％；LiNi 0.85Al 0.075Mn 0.075O 2的质量分数为 50wt％，多孔生物质碳的质量分数为10wt％，富锂化合物的质量分数为25％。本实施例提供上述混合电容器的正极的制备方法，包括以下步骤：
(1)将乙炔黑、PVDF、多孔生物质碳、LiNi 0.85Al 0.075Mn 0.075O 2和Co/氟化锂复合物干混2h后，加入石墨烯和碳纳米管的混合物，搅拌混合3h，然后加入NMP搅拌6h，得到正极浆料；
(2)向集流体表面涂覆质量分数为3％的PTFE和乙炔黑的分散液，在180℃下烘烤，制备粘结层，控制粘结层的厚度为3μm，再将步骤(1)中得到的正极浆料涂覆于所述粘结层表面，在150℃下烘烤，得到中间产品；
(3)将步骤(2)中得到的正极片控制辊压速度50m/min，温度200℃进行热压，在150℃，在真空度为60Pa的条件下，烘烤10min，得到所述的正极；
其中，步骤(1)和步骤(2)均在环境温度为30℃，湿度为40％下进行。
实施例5
本实施例提供一种混合电容器的正极，所述正极包括集流体、以及依次位于集流体表面的粘结层和正极材料层；所述粘结层包括第一粘结剂和第三导电剂(具体的，第一粘结剂组成为PTFE，第三导电剂为SP，厚度为4μm)，所述正极材料层中包括第二粘结剂(具体组成为PVDF)、导电剂、正极活性物质和富锂化合物，所述导电剂包括第一导电剂和第二导电剂，第一导电剂为SP，第二导电剂为石墨烯和碳纳米管按质量比为2:5的混合物，第三导电剂为SP；正极活性物质为多孔生物质碳和LiNi 0.85Al 0.075Mn 0.075O 2的混合物；富锂化合物为Ni/氟化锂复合物；
其中，以粘结层和正极材料层的总质量为100％计，第一粘结剂和第二粘结剂的总质量分数为3wt％；第一导电剂的质量分数为1％，第二导电剂的质量分 数为1％，第三导电剂的质量分数为5％；LiNi 0.85Al 0.075Mn 0.075O 2的质量分数为5wt％，多孔生物质碳的质量分数为87wt％，富锂化合物的质量分数为3％。
本实施例提供上述混合电容器的正极的制备方法，包括以下步骤：
(1)将SP、PVDF、多孔生物质碳、LiNi 0.85Al 0.075Mn 0.075O 2和Ni/氟化锂复合物干混2h后，加入石墨烯和碳纳米管的混合物，搅拌混合3h，然后加入NMP搅拌6h，得到正极浆料；
(2)向集流体表面涂覆质量分数为1％的PTFE和SP的分散液，在180℃下烘烤，制备粘结层，控制粘结层的厚度为10μm，再将步骤(1)中得到的正极浆料涂覆于所述粘结层表面，在150℃下烘烤，得到中间产品；
(3)将步骤(2)中得到的正极片控制辊压速度50m/min，温度270℃进行热压，在150℃，在真空度为180Pa的条件下，烘烤10min，得到所述的正极；
其中，步骤(1)和步骤(2)均在环境温度为30℃，湿度为40％下进行。
实施例6
与实施例1相比，区别仅在于，将步骤(3)中的热压替换为5℃冷压。
实施例7
与实施例1相比，区别仅在于，将步骤(3)中的热压替换为40℃冷压。
实施例8
与实施例1相比，区别仅在于，钴酸锂和活性炭的总质量占比与实施例1相同，均为85％，且钴酸锂与活性炭的质量之比为2.5:1。
实施例9
与实施例1相比，区别仅在于，与实施例1相比，区别仅在于，钴酸锂和活性炭的总质量占比与实施例1相同，均为85％，且钴酸锂与活性炭的质量之 比为2:8。
对比例1
与实施例1相比，区别仅在于，本对比例提供的正极的制备方法中不加入富锂化合物Li 2NiO 2，而保持正极材料层中其余物质之间的质量比不变。
对比例2
与实施例1相比，区别仅在于，本对比例提供的正极的制备方法中不加入活性炭，而用等量的钴酸锂替换。
对比例3
与实施例1相比，区别仅在于，本对比例提供的正极的制备方法中不加入石墨烯和碳纳米管的混合物，而用等量的石墨粉替换。
对比例4
与实施例1相比，区别在于，未设置粘结层，且保持正极材料层中粘结剂的含量与实施例1中第一粘结剂和第二粘结剂的总量相同。
混合电容器性能的评价：
将上述实施例和对比例制备混合电容器正极，与石墨负极组装成电容器，进行容量、室温倍率和-40℃低温测试，测试方法如下：
容量测试：将混合电容器置于25℃的环境，搁置5min，5mA恒流恒压充电至3.9V，截止电流为0.5mA；搁置5min，5mA恒流放电至2.2V，结束。
倍率测试：将混合电容器置于25℃的环境，新威5V5A精密放电柜5mA恒流恒压充电至3.68V，截止电流0.5mA；搁置5min，500C倍率，脉冲放电1s，记录最低电压，结束。
-40℃低温测试：将混合电容器置于25℃的环境，5V5A精密放电柜5mA 恒流恒压充电至3.68V，截止电流0.5mA；混合电容器转移至高低温箱中-40℃环境静置6h，150C倍率脉冲0.1s，记录最低电压，结束。
本申请各实施例和对比例制备的电池为相同型号(15500)，容量越高，代表能量密度越高。
测试结果如表1所示。
表1
Figure PCTCN2020128952-appb-000001
注：表中，25℃&500C电压表示在25℃，电流为500C的条件下，测试的 最低电压；-40℃&150C电压表示在-40℃，电流为150C的条件下，测试的最低电压。
25℃&500C电压和-40℃&150C电压越高，表明材料的倍率性能越好。
通过表1可以看出以下几点：
(1)综合实施例1和对比例1可以看出，对比例1的正极不含Li 2NiO 2，容量和倍率性能均有下降，由此说明，正极含有Li 2NiO 2，有助于提高混合电容器的能量密度、室温倍率性能和低温倍率性能。
(2)综合实施例1和对比例2可以看出，对比例2的正极活性物质全部为钴酸锂，虽然容量较高，但是倍率性能较差，由此说明，正极含有活性炭和钴酸锂，有助于混合电容器兼顾良好的能量密度、室温倍率性能和低温倍率性能；
(3)综合实施例1和对比例3可以看出，对比例3的正极不含石墨烯和碳纳米管的混合物，而由石墨粉代替，导致容量和倍率性能下降，由此说明，正极含有石墨烯和碳纳米管的混合物，有助于提高混合电容器的能量密度、室温倍率性能和低温倍率性能。
(4)综合实施例1和对比例4可以看出，对比例4未设置粘结层，导致倍率性能下降，由此说明，正极材料层和集流体之间设置的粘结层有助于提高混合电容器的室温倍率性能和低温倍率性能。
(5)综合实施例1、实施例8和实施例9可以看出，含锂正极活性物质和碳类活性物质的添加量对于材料的容量和倍率性能有重要影响，含锂正极活性物质和碳类正极活性物质的质量比在1:(0.5-1.5)的可选范围内可以更好地兼顾上述两方面的效果。
申请人声明，本申请通过上述实施例来说明本申请的详细结构特征，但本 申请并不局限于上述详细结构特征，即不意味着本申请必须依赖上述详细结构特征才能实施。

Claims (13)

  1. 一种混合电容器的正极，其包括集流体，以及依次位于集流体表面的粘结层和正极材料层；
    其中所述粘结层包括第一粘结剂，所述正极材料层中包括第二粘结剂、导电剂、正极活性物质和富锂化合物。
  2. 根据权利要求1所述的正极，其中，所述粘结层的厚度为0.5-10μm。
  3. 根据权利要求1或2所述的正极，其中，所述导电剂中包括第一导电剂和第二导电剂，所述第一导电剂包括石墨粉、导电碳黑或乙炔黑中的至少一种，所述第二导电剂包括石墨烯类材料以及一维碳材料中的至少一种。
  4. 根据权利要求1-3中任一项所述的正极，其中，所述粘结层的厚度为1-5μm；
    可选地，所述正极活性物质包括含锂正极活性物质和碳类正极活性物质；
    可选地，所述含锂正极活性物质包括钴酸锂、镍酸锂、锰酸锂、磷酸亚铁锂、镍钴锰三元材料、镍钴铝三元材料或镍钴锰铝四元材料中的任意一种或至少两种的组合，可选为镍酸锂、镍钴锰三元材料、镍钴铝三元材料或镍钴锰铝四元材料中的任意一种或至少两种的组合；
    可选地，所述碳类正极活性物质包括活性炭、石墨烯、掺杂石墨烯或多孔生物质碳中的任意一种或至少两种的组合。
  5. 根据权利要求2-4中任一项所述的正极，其中，所述导电碳黑包括粒径为10-200nm的小颗粒导电碳黑和/或粒径为1-30μm的大颗粒导电碳黑；
    可选地，所述石墨烯类材料包括石墨烯、氧化石墨烯或掺杂石墨烯中的任意一种或至少两种的组合；
    可选地，所述一维碳材料包括碳纳米管和/或碳纤维；
    可选地，所述正极材料层中，石墨烯类材料和一维碳材料的质量比为(1-2):(3-6)；
    可选地，所述第一粘结剂和第二粘结剂为可熔性氟碳树脂；
    可选地，所述第一粘结剂和第二粘结剂独立地选自PVDF、PTFE或PFA中的任意一种或至少两种的组合；
    可选地，所述富锂化合物包括Li 2NiO 2、Li 5FeO 4、Li 3N、Li 2O、Li 2O 2或M/氟化锂复合物中的任意一种或至少两种的组合，其中，M包括Co、Ni或Fe中的任意一种或至少两种的组合，可选为Li 2NiO 2、Li 3N或M/氟化锂复合物中的任意一种或至少两种的组合。
  6. 根据权利要求2所述的正极，其中，所述粘结层中还包括第三导电剂，所述第三导电剂可选为导电碳黑。
  7. 根据权利要求1-6任一项所述的正极，其中，以粘结层和正极材料层的总质量为100％计，所述第一粘结剂和第二粘结剂的总质量分数为2-10％；
    可选地，以粘结层和正极材料层的总质量为100％计，所述第一导电剂的质量分数为1-6％；
    可选地，以粘结层和正极材料层的总质量为100％计，所述石墨烯类材料和一维碳材料的总质量分数为0.5-3％；
    可选地，所述第三导电剂与第一粘结剂的质量比为(1-5):1，可选为(2-4):1；
    可选地，以粘结层和正极材料层的总质量为100％计，所述含锂正极活性物质的质量分数为5-80％；
    可选地，以粘结层和正极材料层的总质量为100％计，所述碳类正极活性物质的质量分数为10-90％；
    可选地，以粘结剂和正极材料层的总质量为100％计，所述正极活性物质的质量分数为85％-95％；
    可选地，所述含锂正极活性物质和碳类正极活性物质的质量比为1:(0.5-1.5)，可选为1:(1-1.2)；
    可选地，以粘结层和正极材料层的总质量为100％计，所述富锂化合物的质量分数2-30％。
  8. 根据权利要求1-7任一项所述的正极的制备方法，其包括以下步骤：
    (1)将第二粘结剂、导电剂、正极活性物质和富锂化合物混合，得到正极浆料，所述导电剂包括第一导电剂和第二导电剂，所述第一导电剂包括石墨粉、导电碳黑或乙炔黑中的至少一种，所述第二导电剂包括石墨烯类材料以及一维碳材料中的至少一种；
    (2)向集流体表面涂覆含有第一粘结剂的分散液，进行第一次烘烤，制备粘结层，再将步骤(1)中得到的正极浆料涂覆于所述粘结层表面，进行第二次烘烤，得到中间产品；
    (3)将步骤(2)中得到的中间产品进行碾压，第三次烘烤，得到所述的正极。
  9. 根据权利要求8所述的制备方法，其中，步骤(2)所述集流体包括腐蚀集流体、涂覆集流体、纯集流体或通孔集流体中的任意一种；
    可选地，步骤(2)所述的分散液中，粘结剂的质量分数为1-10％，可选为2-8％；
    可选地，步骤(2)所述的分散液中，还包括第三导电剂；
    可选地，步骤(2)所述第一次烘烤的温度60-180℃，可选为80-150℃；
    可选地，步骤(2)所述粘结层的厚度为0.5-10μm，可选为1-5μm；
    可选地，步骤(2)所述第二次烘烤的温度80-150℃，可选为100-130℃。
  10. 根据权利要求8或9所述的制备方法，其中，步骤(1)和(2)过程中控制环境温度为20-30℃，湿度3-40％。
  11. 根据权利要求8-10任一项所述的制备方法，其中，步骤(3)所述碾压的速率2-50m/min；
    可选地，步骤(3)所述碾压的方式为冷压和/或热压；
    可选地，所述冷压的温度0-45℃；
    可选地，所述热压的温度60-270℃，可选为80-250℃；
    可选地，步骤(3)所述第三次烘烤的方式包括真空烘烤；
    可选地，所述真空烘烤的真空度为5-200Pa；
    可选地，步骤(3)所述第三次烘烤的温度为80-150℃；
    可选地，步骤(3)所述第三次烘烤的时间为10-60min。
  12. 根据权利要求8-11任一项所述的制备方法，其包括以下步骤：
    (1)将第一导电剂、第二粘结剂、正极活性物质和富锂化合物干混1-3h后，加入第二导电剂搅拌混合1-2h，然后加入有机溶剂搅拌4-6h，得到正极浆料；
    (2)向集流体表面涂覆第一粘结剂的分散液，在60-180℃下烘烤，制备粘结层，控制所述粘结层的厚度为0.5-10μm，再将步骤(1)中得到的正极浆料涂覆于所述粘结层表面，在80-150℃下烘烤，得到中间产品；
    (3)将步骤(2)中得到的中间产品控制辊压速度2-50m/s，温度60-270℃进行热压，在80-150℃，真空度为5-200Pa的条件下，烘烤10-60min，得到所 述的正极；
    其中，步骤(1)和步骤(2)均在温度为20-30℃，湿度为3-40％的环境下进行。
  13. 一种混合电容器，其中，所述混合电容器包括如权利要求1-7任一项所述的正极。
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