WO2023097467A1 - 正极浆料组合物及包含其的正极极片、二次电池、电池模块、电池包和用电装置 - Google Patents

正极浆料组合物及包含其的正极极片、二次电池、电池模块、电池包和用电装置 Download PDF

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WO2023097467A1
WO2023097467A1 PCT/CN2021/134474 CN2021134474W WO2023097467A1 WO 2023097467 A1 WO2023097467 A1 WO 2023097467A1 CN 2021134474 W CN2021134474 W CN 2021134474W WO 2023097467 A1 WO2023097467 A1 WO 2023097467A1
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lithium
positive electrode
binder
battery
formula
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PCT/CN2021/134474
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English (en)
French (fr)
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谢浩添
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宁德时代新能源科技股份有限公司
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Priority to EP21962754.4A priority Critical patent/EP4228036A1/en
Priority to PCT/CN2021/134474 priority patent/WO2023097467A1/zh
Priority to CN202180092814.0A priority patent/CN116848672A/zh
Priority to US18/119,382 priority patent/US20230231130A1/en
Publication of WO2023097467A1 publication Critical patent/WO2023097467A1/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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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 application relates to the technical field of secondary batteries, in particular to a positive electrode slurry composition and a positive electrode sheet containing the same, a secondary battery, a battery module, a battery pack and an electrical device.
  • the present application is completed in view of the above problems, and its purpose is to provide a positive electrode slurry composition, so that the secondary battery corresponding to the positive electrode sheet containing the positive electrode slurry composition has good storage performance and safety performance.
  • the present application provides a positive electrode slurry composition and a positive electrode sheet containing the same, a secondary battery, a battery module, a battery pack and an electrical device.
  • the first aspect of the present application provides a positive electrode slurry composition, wherein the composition contains a positive electrode active material, a lithium supplementing agent and a binder,
  • the positive electrode active material includes lithium-containing phosphate represented by formula (I),
  • M1 is selected from at least one of transition metal elements and non-transition metal elements except Fe and Mn;
  • the lithium replenishing agent is selected from Li a1 M 2 O 0.5(2+a1) , Li 2 M 3 O 3 , Li 2 M 4 O 4 , Li 3 M 5 O 4 , Li 5 M 6 O 4 , Li 5 M One or more of 7 O 6 lithium metal oxides,
  • a1 ⁇ 1, M2 is selected from one or more of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Sn, and M3 is selected from Ni, Co, Fe, Mn, Sn, Cr One or more of them, M4 is selected from one or more of Ni, Co, Fe, Mn, Sn, Cr, V, Nb, M5 is selected from Ni, Co, Fe, Mn, Sn, Cr One or more of , V, Mo, Nb, M 6 is selected from one or more of Ni, Co, Fe, Mn, Sn, Cr, Mo, M 7 is selected from Ni, Co, Mn One or several, the valence state of each element in M 2 , M 3 , M 4 , M 5 , M 6 , M 7 is lower than its own highest oxidation valence state; and
  • Described binder is as shown in formula (II):
  • R 1 and R 2 are independently H or F, x, y, and z are all positive integers, and 0.52 ⁇ (4x+3y+2z)/(4x+4y+4z) ⁇ 0.7.
  • the slurry composition when the positive electrode slurry composition contains the above substances at the same time, the slurry composition is not easy to agglomerate and has high stability, which is conducive to improving the processability of the positive electrode sheet. Therefore, including the positive electrode described in the first aspect of the application
  • the secondary battery of the positive pole sheet of the slurry composition has good storage performance and safety performance.
  • the lithium supplementing agent at least includes a lithium metal oxide represented by formula (III),
  • M8 is selected from one or more of Zn, Sn, Mg, Fe and Mn, optionally, 1 ⁇ a2 ⁇ 2 , 0 ⁇ b2 ⁇ 0.6, 0.01 ⁇ c2 ⁇ 0.08.
  • the weight average molecular weight of the binder of formula (II) is 500,000 to 1.2 million.
  • a binder with a weight average molecular weight within the above range is conducive to obtaining good manufacturability of the positive electrode sheet, and meanwhile, the electrochemical performance corresponding to the secondary battery is also good.
  • the mass fraction of the binder in the composition is 0.2wt%-10wt%, optionally 0.5wt%-4wt%, further optionally 1wt%-3.5wt% , more preferably 1.5wt%-3wt%.
  • the content of the binder in the positive electrode slurry composition is within the above range, the gel problem of the positive electrode slurry composition can be further alleviated, and a stronger bond can be formed between the lithium supplementing agent and the positive electrode active material Therefore, the energy density and cycle life of the battery can be improved.
  • the mass ratio of the binder of the formula (II) to the lithium supplementing agent in the composition is 0.2-2, optionally 0.4-1.5, further optionally 0.7-1.0.
  • an appropriate mass ratio of the binder to the lithium supplementing agent is conducive to further improving the cycle performance and safety performance of the battery.
  • the mass fraction of the lithium-supplementing agent in the composition is 0.1wt%-10wt%, optionally 2wt%-7wt%.
  • the mass fraction of the lithium-supplementing agent in the positive electrode slurry composition is within the above range, it can effectively supplement the loss of active lithium due to the generation of SEI film (Solid Electrolyte Interphase, solid electrolyte interface film) at the negative electrode on the one hand, and on the other hand On the one hand, it can also avoid the lack of reversible lithium intercalation vacancies in the positive electrode due to too high content of lithium supplementing agent, which affects the energy density of the battery cell.
  • SEI film Solid Electrolyte Interphase, solid electrolyte interface film
  • the lithium supplement agent has a volume average particle diameter D50 of 5 ⁇ m-15 ⁇ m
  • the positive electrode active material has a volume average particle diameter D50 of 0.5 ⁇ m-5 ⁇ m.
  • the pH of the lithium supplement agent is ⁇ 13; alternatively, pH ⁇ 12.5; further optionally, 11 ⁇ pH ⁇ 12.5.
  • the pH of the lithium supplementing agent is within the above range, it is beneficial to further reduce the risk of gelation of the positive electrode slurry composition, and further improve the processability and flatness of the positive electrode sheet, thereby helping to further improve the first time of the battery. charge and discharge capacity and cycle life.
  • the outside of the lithium supplementing agent can be coated with a single-layer or multi-layer coating layer, and the coating layer includes one or more of the following materials: metal fluorides, oxides, metal phosphoric acid Salt, lithium salt, carbon element, polymer containing five-membered heterocycle.
  • the coating layer containing the above materials is further coated on the outside of the lithium supplementing agent, the problem of degrading the charging and discharging gram capacity caused by the strong alkalinity of the lithium supplementing agent can be avoided, thereby further improving the storage capacity of the battery cell. performance.
  • the cladding layer comprises one or more of the following materials: AlF 3 , V 2 O 5 , Al 2 O 3 , ZrO 2 , TiO 2 , ZnO, Co 3 O 4 , SiO 2 , AlPO 4. FePO 4 , Co 3 (PO 4 ) 2 , Ni 3 (PO 4 ) 2 , Li 3 PO 4 , Li 2 MnO 3 , LiAlO 2 , Li 2 TiO 3 , Li 2 ZrO 3 , graphene, carbon nanotubes , Poly 3,4-ethylenedioxythiophene, polypyrrole.
  • the specific surface area of the lithium supplement agent is 0.5m 2 /g-20m 2 /g, optionally 1.0m 2 /g-19m 2 /g, further optionally 2m 2 /g - 18m 2 /g, more optionally 5m 2 /g - 17m 2 /g.
  • the lithium replenishing agent has a higher delithiation speed, which is conducive to replenishing the lithium ions consumed in the circulation process in time, ensuring the amount of active lithium, and avoiding the loss of battery capacity due to lithium ions.
  • the ions are greatly reduced to cause "capacity diving"; at the same time, it is also beneficial to reduce the pH value of the lithium supplementing agent, which is beneficial to further improving the stability of the positive electrode slurry composition.
  • the composition also includes one or more of the following substances as binder: carboxymethyl cellulose, hydroxypropyl cellulose , polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, starch, polyvinyl pyrrolidone, polyethylene, polypropylene, ethylene-propylene-propylene terpolymer or sulfonated ethylene-propylene-propylene Diene terpolymer, ethylene-propylene-butadiene terpolymer or sulfonated ethylene-propylene-butadiene terpolymer, ethylene-propylene-pentadiene terpolymer or sulfonated ethylene - propylene-pentadiene terpolymers, ethylene-propylene-hexadiene terpolymers or sulfonated ethylene-propylene-hexadiene terpolymers or sulfonated
  • the composition also includes one or more of the following substances as a dispersant: sodium polyacrylate, sodium dodecylbenzenesulfonate, polypentenenitrile, polyacrylonitrile, and phenol polyoxyethylene ether.
  • the dispersant is phenol ethoxylate.
  • the positive active material includes lithium iron phosphate, and one or more of lithium iron phosphate, lithium manganese phosphate, lithium titanium phosphate, lithium cobalt phosphate, and lithium vanadium phosphate.
  • the second aspect of the present application provides a positive electrode sheet, which includes the positive electrode slurry composition described in the first aspect of the present application.
  • the mass fraction of the positive electrode slurry composition in the film layer of the positive electrode sheet is not lower than 80%, optionally not lower than 90%, further optionally not lower than 95% .
  • the third aspect of the present application provides a secondary battery, which includes the positive electrode sheet described in the second aspect of the present application.
  • the preparation of the secondary battery can adopt the methods known in the prior art for the preparation of secondary batteries.
  • the fourth aspect of the present application provides a battery module, which includes the secondary battery of the third aspect of the present application.
  • the battery module can be prepared using methods known in the prior art for preparing battery modules.
  • the fifth aspect of the present application provides a battery pack, which includes at least one of the secondary battery of the third aspect of the present application or the battery module of the fourth aspect of the present application.
  • the battery pack can be prepared using methods known in the prior art for preparing battery packs.
  • the sixth aspect of the present application provides an electric device, which includes at least one of the secondary battery of the third aspect of the present application, the battery module of the fourth aspect of the present application, or the battery pack of the fifth aspect of the present application.
  • the preparation of the electric device can adopt the methods known in the prior art for the preparation of the electric device.
  • the positive electrode slurry composition contains lithium-containing phosphate and a lithium-supplementing agent
  • the lithium-supplementing agent can replenish the active lithium consumed during the cycle in time, which helps to improve the storage performance of lithium-containing phosphate batteries;
  • adding a binder with a fluorine substitution amount and a molecular weight within a certain range in the positive electrode slurry composition can avoid physical gelation due to the molecular chain length of the binder, thereby improving the chemical gelation of the positive electrode slurry composition question.
  • the positive electrode sheet made of the above positive electrode slurry composition can also be effectively controlled to ensure the bonding strength between the positive electrode active material and the lithium supplementing agent in the positive electrode sheet, and improve the processability of the positive electrode sheet, thereby improving the Battery storage performance and safety performance.
  • this binder can create pores on the surface of the positive electrode, and the surface pores are conducive to electrolyte infiltration, increasing the liquid absorption rate and reducing battery resistance.
  • the battery module, battery pack and electric device of the present application include the secondary battery provided by the present application, and thus have at least the same advantages as the secondary battery.
  • Fig. 1 is a scanning electron microscope picture of the surface of the positive pole sheet corresponding to Comparative Example 2 (left) and Example 1 (right).
  • FIG. 2 is a graph of storage capacity retention (%) at 60° C. versus time of batteries respectively comprising the positive electrode sheets of Comparative Example 1 and Example 17 of the present application.
  • Fig. 3 is a picture of the gel state of the positive electrode slurry described in the present application with mild gel (Fig. 3a), moderate gel (Fig. 3b) and severe gel (Fig. 3c).
  • Fig. 4 is a photo of the surface topography of the positive electrode sheet under an electron microscope CCD (Quantum QLS scope) (magnification 50-100 times) according to an embodiment of the present application.
  • CCD Quantum QLS scope
  • FIG. 5 is a schematic diagram of a lithium ion battery according to an embodiment of the present application.
  • FIG. 6 is an exploded view of the lithium ion battery according to one embodiment of the present application shown in FIG. 5 .
  • FIG. 7 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 8 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 9 is an exploded view of the battery pack according to one embodiment of the present application shown in FIG. 8 .
  • FIG. 10 is a schematic diagram of an electrical device according to an embodiment of the present application.
  • any lower limit can be combined with any upper limit to form an unexpressed range; and any lower limit can be combined with any other lower limit to form an unexpressed range, and likewise any upper limit can be combined with any other upper limit to form an unexpressed range.
  • each individually disclosed point or individual value may serve as a lower or upper limit by itself in combination with any other point or individual value or with other lower or upper limits to form a range not expressly recited.
  • the volume average particle diameter D50 refers to the particle diameter corresponding to when the cumulative volume distribution percentage of the sample to be tested reaches 50%.
  • the volume average particle diameter D50 can be measured by laser diffraction particle size analysis.
  • a laser particle size analyzer such as Malvern Master Size 3000 is used for measurement.
  • the inventors have found in practical work that when adding a lithium-supplementing agent to the positive electrode sheet of a lithium secondary battery, if the lithium-supplementing agent is directly added to the positive electrode slurry, it may cause the positive electrode slurry to gel, thereby affecting the positive electrode.
  • the coating of the slurry affects the storage performance and safety performance of the secondary battery.
  • the inventors unexpectedly found after conducting a large number of experiments that by including a specific type of binder in the positive electrode slurry, the problem of gelation of the positive electrode slurry can be effectively solved, thereby improving the stability of the positive electrode slurry, Further, the storage performance and safety performance of the secondary battery are improved.
  • the first aspect of the present application provides a positive electrode slurry composition, wherein the composition contains a positive electrode active material, a lithium supplementing agent and a binder,
  • the positive electrode active material includes lithium-containing phosphate represented by formula (I),
  • M1 is selected from at least one of transition metal elements and non-transition metal elements except Fe and Mn;
  • the lithium replenishing agent is selected from Li a1 M 2 O 0.5(2+a1) , Li 2 M 3 O 3 , Li 2 M 4 O 4 , Li 3 M 5 O 4 , Li 5 M 6 O 4 , Li 5 M One or more of 7 O 6 lithium metal oxides,
  • a1 ⁇ 1, M2 is selected from one or more of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Sn, and M3 is selected from Ni, Co, Fe, Mn, Sn, Cr One or more of them, M4 is selected from one or more of Ni, Co, Fe, Mn, Sn, Cr, V, Nb, M5 is selected from Ni, Co, Fe, Mn, Sn, Cr One or more of , V, Mo, Nb, M 6 is selected from one or more of Ni, Co, Fe, Mn, Sn, Cr, Mo, M 7 is selected from Ni, Co, Mn One or several, the valence state of each element in M 2 , M 3 , M 4 , M 5 , M 6 , M 7 is lower than its own highest oxidation valence state; and
  • Described binder is as shown in formula (II):
  • R 1 and R 2 are independently H or F, x, y, and z are all positive integers, and 0.52 ⁇ (4x+3y+2z)/(4x+4y+4z) ⁇ 0.7.
  • H there is a large amount of H in the positive electrode slurry, which may cause the binder to release a large amount of HF.
  • the positive electrode slurry produces chemical gel, which seriously affects the production capacity and the reliability of the secondary battery.
  • F there is a large amount of F in the positive electrode slurry, indicating that the content of tetrafluoroethylene in the binder is high, which may not be conducive to the binder to fully exert its binding effect, thereby improving the performance of the secondary battery.
  • the positive electrode slurry composition contains lithium-containing phosphate and a lithium-supplementing agent
  • the lithium-supplementing agent can replenish the active lithium consumed during the cycle in time, which helps to improve the storage performance of lithium-containing phosphate batteries;
  • adding a binder with a fluorine substitution amount and a molecular weight within a certain range in the positive electrode slurry composition can avoid physical gelation due to the long molecular chain of the binder, and can also improve the chemical gelation of the positive electrode slurry composition.
  • the binder of formula (II) can create pores on the surface of the positive electrode, and the surface pores are conducive to electrolyte infiltration, increasing the liquid absorption rate and reducing battery resistance.
  • the lithium supplementing agent includes a lithium metal oxide represented by formula (III),
  • M8 is selected from one or more of Zn, Sn, Mg, Fe and Mn, optionally, 1 ⁇ a2 ⁇ 2 , 0 ⁇ b2 ⁇ 0.6, 0.01 ⁇ c2 ⁇ 0.08.
  • the positive electrode sheet made of the above positive electrode slurry composition has higher charge specific capacity and discharge specific capacity.
  • the inventors found that: when the Cu content in the lithium metal oxide represented by the formula (III) is small, the NiO in the lithium replenishing agent is relatively large, which is not conducive to the development of capacity. Therefore, in order to achieve good lithium supplementation effect, optionally, in the lithium metal oxide represented by formula (III), 1 ⁇ a2 ⁇ 2, 0 ⁇ b2 ⁇ 0.6, 0.01 ⁇ c2 ⁇ 0.08.
  • the binder of formula (II) has a weight average molecular weight of 500,000 to 1.2 million.
  • the positive electrode sheet when the weight average molecular weight of the binder is 500,000 to 1,200,000, the positive electrode sheet can obtain good manufacturability, and the electrochemical performance of the corresponding secondary battery is also good. better.
  • the weight average molecular weight of the binder is too large, its molecular chain is longer, which is easy to cause particle agglomeration and produce physical gel.
  • the weight-average molecular weight of the binder is too small, its molecular chain is relatively short, which may result in insufficient cohesiveness, thereby causing the pole piece to be released from the mold.
  • the mass fraction of the binder in the composition is 0.2wt%-10wt%, optionally 0.5wt%-4wt%, further optionally 1wt% - 3.5 wt%, more preferably 1.5 wt% - 3 wt%.
  • the positive electrode active material layer contains an appropriate amount of the above-mentioned binder, which can effectively alleviate the slurry gel problem, and form a strong bonding effect between the lithium supplementing agent and the positive electrode active material, so that the energy density and cycle life of the battery are even. can be improved.
  • the mass fraction of the binder in the positive electrode sheet is too small, it may lead to insufficient bonding between the binder, the active ingredient and the lithium-supplementing agent, causing the active material and the lithium-supplementing agent to fall off, causing safety problems.
  • the mass fraction of the binder in the positive electrode sheet is too large, it may lead to poor conductivity of the electrode sheet, deteriorate the battery impedance, and affect the kinetic performance of the secondary battery.
  • the mass ratio of the binder of the formula (II) to the lithium supplementing agent in the composition is 0.2-2, optionally 0.4-1.5, further Optionally 0.7-1.0.
  • the inventors unexpectedly found that when the mass ratio of the lithium-supplementing agent to the binder is within the above range, it is beneficial to give full play to the binding effect of the binder, and it is also beneficial to suppress the positive electrode slurry composition.
  • the physical gel and chemical gel can improve the safety performance and storage performance of secondary batteries.
  • the mass fraction of the lithium-supplementing agent in the composition is 0.1wt%-10wt%, optionally 2wt%-7wt%.
  • the content of the lithium-supplementing agent When the content of the lithium-supplementing agent is lower than the above-mentioned range, it may not be able to make up for the loss of positive active lithium. When the content of the lithium-supplementing agent is higher than the above-mentioned range, it may cause insufficient reversible lithium intercalation vacancies in the positive electrode, which affects the energy density of the battery cell.
  • the mass fraction of the positive electrode active material in the composition described in the present application is 80wt%-99.5wt%, optionally 88wt%-96wt%.
  • the lithium supplement agent has a volume average particle diameter D50 of 5 ⁇ m-15 ⁇ m
  • the positive electrode active material has a volume average particle diameter D50 of 0.5 ⁇ m-5 ⁇ m.
  • the volume average particle diameter D50 of the lithium replenishing agent when the volume average particle diameter D50 of the lithium replenishing agent is within the above range, it has a faster delithiation speed, which is beneficial to make up for the capacity loss caused by the low first effect, thereby improving the cycle performance of the battery.
  • the pH of the lithium supplement agent is ⁇ 13; alternatively, pH ⁇ 12.5; further optionally, 11 ⁇ pH ⁇ 12.5.
  • the pH of the lithium supplementation agent is within the above range, it is beneficial to further reduce the risk of gelation of the lithium supplementation layer slurry, further improve the lithium supplementation effect, and thereby increase the initial charge and discharge capacity and cycle life of the battery.
  • the lithium supplementary agent used in this application is highly sensitive to water, when the pH of the lithium supplementary agent is too high, the lithium supplementary agent is highly alkaline, which may affect the discharge capacity after the lithium supplementary agent absorbs water. Capacity, which is not conducive to improving battery performance.
  • the method for measuring the pH of the lithium supplement agent can be a method commonly used by those skilled in the art, such as a titration method.
  • the lithium supplement agent is coated with a single-layer or multi-layer coating layer, and the coating layer includes one or more of the following materials: metal fluorides, oxides, Metal phosphates, lithium salts, simple carbon, polymers containing five-membered heterocyclic rings.
  • the cladding layer includes one or more of the following materials: AlF 3 , V 2 O 5 , Al 2 O 3 , ZrO 2 , TiO 2 , ZnO, Co 3 O 4 , SiO 2 , AlPO 4 , FePO 4 , Co 3 (PO 4 ) 2 , Ni 3 (PO 4 ) 2 , Li 3 PO 4 , Li 2 MnO 3 , LiAlO 2 , Li 2 TiO 3 , Li 2 ZrO 3 , Graphene , carbon nanotubes, poly 3,4-ethylenedioxythiophene, polypyrrole.
  • the specific surface area of the lithium supplement agent is 0.5m 2 /g-20m 2 /g, optionally 1.0m 2 /g-19m 2 /g, and further optionally 2m 2 /g-18m 2 /g, more optionally 5m 2 /g-17m 2 /g.
  • the test of the specific surface area can be carried out by methods commonly used in this field, for example, it can be carried out according to the standard GB/T19587-2004.
  • the lithium ions consumed by the negative electrode can be effectively and timely replenished to ensure the amount of active lithium, thereby improving the capacity performance of the secondary battery.
  • the composition further includes one or more of the following substances as binders: carboxymethylcellulose, hydroxyl Propyl cellulose, polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, starch, polyvinyl pyrrolidone, polyethylene, polypropylene, ethylene-propylene-propylene terpolymer or sulfonated ethylene - propylene-propylene terpolymers, ethylene-propylene-butadiene terpolymers or sulfonated ethylene-propylene-butadiene terpolymers, ethylene-propylene-pentadiene terpolymers or Sulfonated ethylene-propylene-pentadiene terpolymer, ethylene-propylene-hexadiene terpolymer or sulfonated ethylene-propylene-he
  • the composition also includes one or more of the following substances as a dispersant: sodium polyacrylate, sodium dodecylbenzenesulfonate, polypentenenitrile, polyacrylonitrile, and phenol polyoxyethylene ether.
  • Adding a dispersant to the positive electrode slurry composition of the present application is beneficial to increase the porosity and reduce the lithium ion migration resistance, thereby reducing the DC resistance and improving the kinetic performance.
  • the dispersant is phenol ethoxylate.
  • the positive electrode active material represented by formula (I) includes lithium iron phosphate, and one of lithium iron phosphate, lithium manganese phosphate, lithium titanium phosphate, lithium cobalt phosphate, and lithium vanadium phosphate or more.
  • the second aspect of the present application provides a positive electrode sheet, wherein the positive electrode sheet includes the positive electrode slurry composition described in the first aspect of the present application.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode collector, and the positive electrode film layer includes the positive electrode slurry composition according to the first aspect of the present application.
  • the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposing surfaces of the positive electrode current collector.
  • the positive electrode current collector can be a metal foil or a composite current collector.
  • aluminum foil can be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene glycol ester
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode film layer may further include a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the mass fraction of the positive electrode slurry composition in the film layer of the positive electrode sheet is not lower than 80%, optionally not lower than 90%, and further optionally not less than 95%.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive electrode active material, lithium replenishing agent, binder, conductive agent and any other components are dispersed in The positive electrode slurry is formed in a solvent (such as N-methylpyrrolidone); the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposing surfaces of the negative electrode current collector.
  • the negative electrode current collector can use a metal foil or a composite current collector.
  • copper foil can be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • Composite current collectors can be formed by metal materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • the negative electrode active material can be a negative electrode active material known in the art for batteries.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of simple tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials of batteries can also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode film layer may further optionally include a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer may also optionally include a conductive agent.
  • the conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer may optionally include other additives, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • CMC-Na sodium carboxymethylcellulose
  • the negative electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the present application has no specific limitation on the type of electrolyte, which can be selected according to requirements.
  • electrolytes can be liquid, gel or all solid.
  • the electrolyte is an electrolytic solution.
  • the electrolyte solution includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorooxalate borate, lithium difluorodifluorooxalatephosphate and lithium tetrafluorooxalatephosphate.
  • the solvent may be selected from ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, Butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte may optionally include additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performances of the battery, such as additives that improve battery overcharge performance, additives that improve high-temperature or low-temperature performance of batteries, and the like.
  • a separator is further included in the secondary battery.
  • the present application has no particular limitation on the type of the isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the separator can be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and there is no particular limitation.
  • the positive pole piece, the negative pole piece and the separator can be made into an electrode assembly through a winding process or a lamination process.
  • the third aspect of the present application provides a secondary battery, which includes the negative electrode active material described in the first aspect of the present application or the positive electrode sheet described in the second aspect of the present application.
  • a secondary battery typically includes a positive pole piece, a negative pole piece, an electrolyte, and a separator.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the separator is arranged between the positive pole piece and the negative pole piece, which mainly plays a role in preventing the short circuit of the positive and negative poles, and at the same time allows ions to pass through.
  • a lithium ion secondary battery may include an outer package.
  • the outer package can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer package of the lithium-ion secondary battery may be a hard case, such as a hard plastic case, aluminum case, steel case, and the like.
  • the outer packaging of the lithium-ion secondary battery may also be a soft bag, such as a pouch-type soft bag.
  • the material of the soft bag may be plastic, and examples of plastic include polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).
  • FIG. 5 shows a secondary battery 5 having a square structure as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plates enclose to form an accommodating cavity.
  • the housing 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening to close the accommodating cavity.
  • the positive pole piece, the negative pole piece and the separator can form the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the accommodating cavity. Electrolyte is infiltrated in the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the lithium-ion secondary battery can be assembled into a battery module, and the number of lithium-ion batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG. 7 is a battery module 4 as an example.
  • a plurality of lithium-ion batteries 5 can be arranged sequentially along the length direction of the battery module 4 .
  • the plurality of lithium ion batteries 5 can be fixed by fasteners.
  • the battery module 4 may also include a housing with an accommodating space, and a plurality of lithium-ion batteries 5 are accommodated in the accommodating space.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3 , the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source of the electric device, and can also be used as an energy storage unit of the electric device.
  • the electric devices may include mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, etc.) , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited thereto.
  • a secondary battery, a battery module or a battery pack can be selected according to its use requirements.
  • FIG. 10 is an example of an electrical device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module may be used.
  • a device may be a cell phone, tablet, laptop, or the like.
  • the device is generally required to be light and thin, and a secondary battery can be used as a power source.
  • binder A The preparation method of binder A, binder B, binder C (C1 ⁇ C6) and dispersant phenol polyoxyethylene ether used in the following examples are as follows:
  • test method of conductivity is as follows: reference standard HG/T 4067-2015.
  • Use the conductivity meter DDSJ-318 first use the sample water to rinse the electrode 2 to 3 times, and at the same time perform temperature correction, repeat the sampling measurement 2 to 3 times, when the measurement result and the relative error are both within 3%, it is the final result.
  • the negative electrode sheet graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), thickener sodium carboxymethyl cellulose (CMC) according to the mass ratio of 96.5 parts by weight: 0.7 parts by weight: 1.8 parts by weight : 1 part by weight is dissolved in deionized water as a solvent, and fully stirred and mixed evenly to obtain negative electrode slurry.
  • the negative electrode slurry is uniformly coated on the negative electrode current collector copper foil, and the negative electrode sheet is obtained through drying, cold pressing and slitting.
  • the surface density of the obtained negative electrode active material layer was 9.8 mg/cm 2 , and the compacted density was 1.65 g/cm 3 .
  • positive electrode sheet active material LiFePO 4 (LFP), conductive agent acetylene black, binding agent A are mixed with the mass ratio of 97 parts by weight: 1 part by weight: 2 parts by weight, dissolved in solvent N-methylpyrrolidone (That is, NMP), and fully stirred and mixed uniformly to obtain positive electrode slurry.
  • the volume average particle diameter D50 of the active material LiFePO 4 particles is 1.2 ⁇ m.
  • the positive electrode slurry is uniformly coated on the aluminum foil, and the positive electrode sheet is obtained through drying, cold pressing and slitting.
  • the surface density of the obtained positive electrode active material layer was 19.5 mg/cm 2 , and the compacted density was 2.4 g/cm 3 .
  • Electrolyte preparation mix the organic solvent ethylene carbonate (EC)/ethyl methyl carbonate (EMC) uniformly according to the weight ratio of 50/50, add LiPF 6 to dissolve in the above-mentioned organic solvent, and stir evenly to make the concentration of LiPF 6 to 1.1 mol/L to obtain an electrolyte solution.
  • EC organic solvent ethylene carbonate
  • EMC ethyl methyl carbonate
  • Preparation of the full battery stack the positive electrode sheet, separator, and negative electrode sheet obtained above in order, so that the separator is in the middle of the positive and negative electrodes to play the role of isolation, and wind up to obtain a bare cell. Place the bare cell in the outer package, inject the above electrolyte and package it to obtain a full battery (hereinafter also referred to as "full battery").
  • Comparative Example 2 Except in the preparation process of the positive electrode sheet, 2 parts by weight of the active material LiFePO 4 was replaced by 2 parts by weight of the lithium supplement Li with a specific surface area of 16.0 m 2 /g, a volume average particle diameter D50 of 5 ⁇ m, and a pH of 12.0. Except for 2 Ni 0.5 Cu 0.5 O 2 (L), the other conditions of Comparative Example 2 are the same as those of Comparative Example 1.
  • Comparative Example 3 The other conditions of Comparative Example 3 were the same as those of Comparative Example 2, except that the binder A was replaced with binder B of equal mass during the preparation of the positive electrode sheet.
  • Example 2 Other conditions of Example 2 were the same as those of Comparative Example 2, except that 50% by weight of binder A was replaced by binder C1 of equal mass during the preparation of the positive electrode sheet.
  • Example 3 Other conditions of Example 3 were the same as those of Comparative Example 2, except that 20% by weight of the binder A was replaced by an equal mass of binder C1 during the preparation of the positive electrode sheet.
  • Example 5 Except in the preparation process of the positive electrode sheet, the specific surface area of the lithium supplement Li 2 Ni 0.5 Cu 0.5 O 2 used is 6.2m 2 /g, and the volume average particle diameter D50 is 11 ⁇ m, and the binder A is completely replaced by Other conditions of Example 5 are the same as those of Example 3 except for the same mass of binder C1.
  • Example 5 Except that in the preparation process of the positive electrode sheet, the specific surface area of the lithium supplement Li 2 Ni 0.5 Cu 0.5 O 2 used is 9.7m 2 /g, and the volume average particle diameter D50 is 8 ⁇ m, other conditions of Example 5 are the same as Example 4 is the same.
  • Embodiments 6-8 except that in the preparation process of the positive electrode sheet, the active material LiFePO of 0.05 parts by weight , 0.10 parts by weight and 0.20 parts by weight were replaced by dispersant phenol polyoxyethylene ethers of equal parts by mass, and the bonding
  • the other conditions of Examples 6-8 are the same as those of Example 3 except that Agent A is completely replaced by binder C1 of equal quality.
  • Example 9 Other conditions of Example 9 were the same as those of Example 3, except that the positive electrode slurry was prepared according to the following method, and the binder A was completely replaced with binder C1 of equal mass.
  • Examples 10-13 Except in the preparation process of the positive electrode sheet, 0.4 parts by weight, 0.8 parts by weight, 1.4 parts by weight and 3.0 parts by weight of the active material LiFePO 4 were replaced by equal parts by mass of the lithium-supplementing agent Li 2 Ni 0.5 Cu 0.5 O 2 , and binder A is completely replaced by binder C1 of equal quality, other conditions of Examples 10-13 are the same as Example 3.
  • Examples 14-17 Except during the preparation of the positive electrode sheet, the pH of the lithium supplement Li 2 Ni 0.5 Cu 0.5 O 2 added to the positive electrode slurry was 11.0, 12.5, 13.0 and 12.0 respectively, and the binder Other conditions of Examples 14-17 are the same as those of Example 3 except that A is completely replaced by binder C1 of equal quality.
  • Examples 18-22 Except in the preparation process of the positive electrode sheet, the binder C1 was replaced with the same quality binder C2, binder C3, binder C4, binder C5 and binder C6 Except, other conditions of Examples 18-22 are the same as Example 17.
  • Example 23 In addition to replacing the lithium-supplementing agent Li 2 Ni 0.5 Cu 0.5 O 2 with an equal mass of lithium-supplementing agent Li 5 FeO 4 with a D50 of 7 ⁇ m and a pH of 13.5 during the preparation of the positive electrode sheet, Example 23 The other conditions are the same as in Example 17.
  • the weight-average molecular weight of the binder was tested by gel permeation chromatography (reference standard: GB/T 21863-2008 gel permeation chromatography GPC uses tetrahydrofuran as eluent).
  • a 0.3% by weight solution of the binder to be tested was prepared using N-methylpyrrolidone (NMP). Take the sample bottle and measure 0.5ml of the solution of the binder to be tested, and set the injection volume at 30-100 ⁇ L. Install the chromatographic column and pipeline, turn on the chromatograph (Waters e2695), and the mobile phase passes through a 0.45 ⁇ m disposable filter (to remove particles, insoluble glue, binder, etc.), and degassed by ultrasonic. The weight average molecular weight of the binder can be obtained by testing after cleaning 2 to 4 times.
  • NMP N-methylpyrrolidone
  • the porosity is tested by the true density method (refer to GB/T24586-2009).
  • Test 3 times take the average value to calculate the average liquid absorption rate V.
  • test method refers to the standard GB/T19587-2004 "Determination of specific surface area of solid substances by gas adsorption BET method".
  • the discharge specific capacity can be obtained by dividing Ed0 by the mass of the positive electrode active material of the battery.
  • Discharge specific capacity (mAh/g) 1st cycle discharge capacity/mass of positive active material
  • Slight gel (as shown in Figure 3a): The slurry has good fluidity, but there is obvious reflection on the liquid surface, and the slurry flow line and the liquid surface are protruding.
  • Moderate gel (as shown in Figure 3b): The fluidity of the slurry is poor, and it is flocculent; the slurry is flocculent, but has no solid nature; there is no jelly block.
  • Severe gel (as shown in Figure 3c): the slurry has no fluidity and is jelly-like; the slurry is solid and has no fluidity, and can be picked up as a whole.
  • the secondary battery Charge the secondary battery to be tested to a voltage of 3.65V at a rate of 1C at room temperature, and then discharge it to a voltage of 2.5V at a rate of 1C.
  • the reversible capacity E0 can be measured directly by reading the instrument.
  • the secondary battery Charge the secondary battery to be tested to a voltage of 3.65V at a rate of 1C at room temperature, and then discharge it to a voltage of 2.5V at a rate of 1C.
  • the reversible capacity E0 can be measured directly by reading the instrument. Then put the secondary battery in a fully charged state in an oven at 60°C, take out the battery every 20 days, test its reversible capacity immediately and record it as En.
  • the background is scanned first, and then the tablet sample is scanned, with the wavenumber range between 400 and 4000cm -1 .
  • the -CF stretching vibration peaks at 1209cm -1 and 1184cm -1 in the infrared spectrum, the -CF stretching vibration peak at 1070cm -1 , and the antisymmetric stretching vibration peaks of -CF 2 at 840cm -1 , the corresponding peak areas are a1, a2, a3, a4.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

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Abstract

本申请提供了一种正极浆料组合物，包含其的正极极片、二次电池、电池模块、电池包和用电装置。本申请所述正极浆料所述组合物中含有正极活性物质、补锂剂和粘结剂，其中所述正极活性物质包括式(I)所示的含锂磷酸盐， LiFe 1-b1-c1Mn b1M 1 c1PO 4 式(I) 其中，0≤b1≤1，0≤c1≤0.1，M 1选自除Fe、Mn外的过渡金属元素以及非过渡金属元素中的至少一种；所述补锂剂选自Li a1M 2O 0.5(2+a1)、Li 2M 3O 3、Li 2M 4O 4、Li 3M 5O 4、Li 5M 6O 4、Li 5M 7O 6的锂金属氧化物中一种或几种，其中，a1≥1，M 2选自Ni、Co、Fe、Mn、Zn、Mg、Ca、Cu、Sn中的一种或几种，M 3选自Ni、Co、Fe、Mn、Sn、Cr中的一种或几种，M 4选自Ni、Co、Fe、Mn、Sn、Cr、V、Nb中的一种或几种，M 5选自Ni、Co、Fe、Mn、Sn、Cr、V、Mo、Nb中的一种或几种，M 6选自Ni、Co、Fe、Mn、Sn、Cr、Mo中的一种或几种，M 7选自Ni、Co、Mn中的一种或几种，M 2、M 3、M 4、M 5、M 6、M 7中每种元素的价态分别低于其自身的最高氧化价态；和所述粘结剂如式(II)所示：其中，R 1、R 2彼此独立地为H或F，x、y、z均为正整数，且0.52≤(4x+3y+2z)/(4x+4y+4z)≤0.7。

Description

正极浆料组合物及包含其的正极极片、二次电池、电池模块、电池包和用电装置 技术领域
本申请涉及二次电池技术领域，尤其涉及一种正极浆料组合物及包含其的正极极片、二次电池、电池模块、电池包和用电装置。
背景技术
二次电池因具有高能量密度、长循环寿命和无记忆效应等优点而被广泛地应用于消费类电子产品中。近年来，随着消费类电子产品和新能源汽车的普及，消费者对锂离子电池的存储性能和安全性能提出了更高的要求，如何设计出一款存储性能优良并且兼具良好安全性能的锂离子电池成为主要研发方向之一。
发明内容
本申请是鉴于上述课题而完成的，其目的在于提供一种正极浆料组合物，使得包含所述正极浆料组合物的正极极片对应的二次电池具备良好的存储性能和安全性能。
为达到上述目的，本申请提供了一种正极浆料组合物及包含其的正极极片、二次电池、电池模块、电池包和用电装置。
本申请的第一方面提供一种正极浆料组合物，其中，所述组合物中含有正极活性物质、补锂剂和粘结剂，
所述正极活性物质包括式(I)所示的含锂磷酸盐，
LiFe 1-b1-c1Mn b1M 1 c1PO 4      式(I)
其中，0≤b1≤1，0≤c1≤0.1，M 1选自除Fe、Mn外的过渡金属元素以及非过渡金属元素中的至少一种；
所述补锂剂选自Li a1M 2O 0.5(2+a1)、Li 2M 3O 3、Li 2M 4O 4、Li 3M 5O 4、Li 5M 6O 4、Li 5M 7O 6的锂金属氧化物中一种或几种，
其中，a1≥1，M 2选自Ni、Co、Fe、Mn、Zn、Mg、Ca、Cu、Sn中的一种或几种，M 3选自Ni、Co、Fe、Mn、Sn、Cr中的一种或几种，M 4选自Ni、Co、Fe、Mn、Sn、Cr、V、Nb中的一种或几种，M 5选自Ni、Co、Fe、Mn、Sn、Cr、V、Mo、Nb中的一种或几种，M 6选自Ni、Co、Fe、Mn、Sn、Cr、Mo中的一种或几种，M 7选自Ni、Co、Mn中的一种或几种，M 2、M 3、M 4、M 5、M 6、M 7中每种元素的价态分别低于其自身的最高氧化价态；和
所述粘结剂如式(II)所示：
Figure PCTCN2021134474-appb-000001
其中，R 1、R 2彼此独立地为H或F，x、y、z均为正整数，且0.52≤(4x+3y+2z)/(4x+4y+4z)≤0.7。
本申请中，正极浆料组合物同时含有上述物质时，浆料组合物不易发生团聚、稳定较高，有利于提升正极极片的可加工性，由此，包含本申请第一方面所述正极浆料组合物的正极极片的二次电池具备良好的存储性能和安全性能。
在任意实施方式中，所述补锂剂至少包括式(III)所示的锂金属氧化物，
Li a2Ni b2Cu 1-b2-c2M 8 c2O 2      式(III)
其中，1<a2＜3，0＜b2＜1，0≤c2＜0.1，M 8选自Zn、Sn、Mg、Fe和Mn中的一种或几种，可选地，1＜a2≤2，0＜b2≤0.6、0.01＜c2＜0.08。
在任意实施方式中，所述式(II)的粘结剂的重均分子量为50万至120万。重均分子量在上述范围内的粘结剂有利于使正极极片获得良好的可制造性，同时对应二次电池的电化学性能也较好。
在任意实施方式中，所述粘结剂在所述组合物中的质量分数为0.2wt％-10wt％，可选地为0.5wt％-4wt％，进一步可选地为1wt％-3.5wt％，更为可选地为1.5wt％-3wt％。
当正极浆料组合物中所述粘结剂的含量在上述范围内时，能进一步缓解正极浆料组合物的凝胶问题，并且使补锂剂与正极活性物质之间形成较强的粘结作用，使得电池的能量密度和循环寿命均能得到改善。
在任意实施方式中，所述式(II)的粘结剂与所述补锂剂在所述组合物中的质量之比为0.2-2，可选地为0.4-1.5，进一步可选地为0.7-1.0。
正极浆料组合物中，所述粘结剂与所述补锂剂的合适的质量比有利于进一步改善电池的循环性能和安全性能。
在任意实施方式中，所述补锂剂在所述组合物中的质量分数为0.1wt％-10wt％，可选地为2wt％-7wt％。
当正极浆料组合物中所述补锂剂的质量分数在上述范围内时，一方面可以有效补足由于负极生成SEI膜(Solid Electrolyte Interphase，固态电解质界面膜)而导致的活性锂的损失，另一方面也可避免由于补锂剂含量太高而造成正极可逆嵌锂空位不足，影响电芯的能量密度。
在任意实施方式中，所述补锂剂的体积平均粒径D50为5μm-15μm，所述正极活性材料的体积平均粒径D50为0.5μm-5μm。
在任意实施方式中，所述补锂剂的pH≤13；可选地，pH≤12.5；进一步可选地，11≤pH≤12.5。
当补锂剂的pH在上述范围内时，有利于进一步降低正极浆料组合物发生凝胶的风险，进一步改善正极极片的可加工性和极片平整度，从而有利于进一步提升电池的首次充放电容量和循环寿命。
在任意实施方式中，所述补锂剂的外侧可以包覆有单层或多层的包覆层，所述包覆层包含一种或多种以下材料：金属氟化物、氧化物、金属磷酸盐、锂盐、碳单质、含五元杂环聚合物。
当在所述补锂剂的外侧进一步包覆包含上述材料的包覆层时，可避免由于补锂剂的碱性较强而导致的恶化充放电克容量的问题，从而进一步改善电芯的存储性能。
在任意实施方式中，所述包覆层包含一种或多种以下材料：AlF 3、V 2O 5、Al 2O 3、ZrO 2、TiO 2、ZnO、Co 3O 4、SiO 2、AlPO 4、FePO 4、Co 3(PO 4) 2、Ni 3(PO 4) 2、Li 3PO 4、Li 2MnO 3、LiAlO 2、Li 2TiO 3、Li 2ZrO 3、石 墨烯、碳纳米管、聚3,4-乙烯二氧噻吩、聚吡咯。
在任意实施方式中，所述补锂剂的比表面积为0.5m 2/g-20m 2/g，可选地为1.0m 2/g-19m 2/g，进一步可选地为2m 2/g-18m 2/g，更为可选地5m 2/g-17m 2/g。
当所述补锂剂的比表面积在上述范围内时，一方面补锂剂具有较高的脱锂速度，有利于及时补充循环过程中消耗的锂离子，保障活性锂数量，避免电池容量由于锂离子大幅减少而出现“容量跳水”；同时，还有利于降低补锂剂的pH值，有利于进一步提升正极浆料组合物的稳定性。
在任意实施方式中，除式(II)所示的粘结剂以外，所述组合物还包括以下物质中的一种或多种作为粘结剂：羧甲基纤维素、羟丙基纤维素、聚丙烯酸、聚偏氟乙烯、聚四氟乙烯、聚乙烯醇、淀粉、聚乙烯吡咯烷酮、聚乙烯、聚丙烯、乙烯-丙烯-丙二烯三元共聚物或磺化的乙烯-丙烯-丙二烯三元共聚物、乙烯-丙烯-丁二烯三元共聚物或磺化的乙烯-丙烯-丁二烯三元共聚物、乙烯-丙烯-戊二烯三元共聚物或磺化的乙烯-丙烯-戊二烯三元共聚物、乙烯-丙烯-己二烯三元共聚物或磺化的乙烯-丙烯-己二烯三元共聚物、苯乙烯丁二烯橡胶、含氟橡胶；和/或，
所述组合物还包括以下物质中的一种或多种作为分散剂：聚丙烯酸钠、十二烷基苯磺酸钠、聚戊烯腈、聚丙烯腈、酚聚氧乙烯醚。
在任意实施方式中，所述分散剂为酚聚氧乙烯醚。
在任意实施方式中，所述正极活性物质包括磷酸铁锂，以及磷酸亚铁锂、磷酸锰锂、磷酸钛锂、磷酸钴锂、磷酸钒锂中的一种或多种。
本申请的第二方面提供一种正极极片，其包括本申请第一方面所述的正极浆料组合物。
在任意实施方式中，所述正极浆料组合物在所述正极极片的膜层中的质量分数不低于80％，可选地不低于90％，进一步可选地不低于95％。
本申请第三方面提供一种二次电池，其包括本申请第二方面所述的正极极片。二次电池的制备可以采用现有技术已知的用于制备二次电池的方法。
本申请第四方面提供一种电池模块，其包括本申请第三方面的二次电 池。电池模块的制备可以采用现有技术已知的用于制备电池模块的方法。
本申请第五方面提供一种电池包，其包括本申请第三方面的二次电池或本申请第四方面的电池模块中的一种以上。电池包的制备可以采用现有技术已知的用于制备电池包的方法。
本申请第六方面提供一种用电装置，其包括本申请第三方面的二次电池或本申请第四方面的电池模块或本申请第五方面的电池包中的一种以上。用电装置的制备可以采用现有技术已知的用于制备用电装置的方法。
[有益效果]
本申请中，正极浆料组合物由于含有含锂磷酸盐以及补锂剂，补锂剂可以及时补充循环过程中消耗的活性锂，有助于提升含锂磷酸盐类电池的存储性能；与此同时，在正极浆料组合物中添加氟取代量和分子量在一定范围内的粘结剂，可避免由于粘结剂分子链长而造成物理凝胶，从而改善正极浆料组合物的化学凝胶问题。同时，还可以有效控制使用上述正极浆料组合物制成的正极极片，确保正极极片中正极活性物质与补锂剂之间的粘结强度，提升正极极片的可加工性，从而提高电池的存储性能和安全性能。此外，此粘结剂可以在正极表面造孔，表面孔洞有利于电解液浸润，提升吸液速率，降低电池电阻。
本申请的电池模块、电池包和用电装置包括本申请提供的二次电池，因而至少具有与所述二次电池相同的优势。
附图说明
图1是对比例2(左)和实施例1(右)对应正极极片表面的扫描电镜图片。
图2是分别包含本申请对比例1和实施例17的正极极片的电池的60℃存储容量保持率(％)与时间的曲线图。
图3是本申请所述正极浆料轻度凝胶(图3a)、中度凝胶(图3b)和严重凝胶(图3c)的凝胶状态图片。
图4是本申请一实施方式的正极极片在电子显微镜CCD(Quantum QLS scope)下(放大50～100倍)的表面形貌图片。
图5是本申请一实施方式的锂离子电池的示意图。
图6是图5所示的本申请一实施方式的锂离子电池的分解图。
图7是本申请一实施方式的电池模块的示意图。
图8是本申请一实施方式的电池包的示意图。
图9是图8所示的本申请一实施方式的电池包的分解图。
图10是本申请一实施方式的用电装置的示意图。
附图标记说明
1电池包
2上箱体
3下箱体
4电池模块
5锂离子电池
51壳体
52电极组件
53顶盖组件
具体实施方式
以下，参照附图进行详细说明，具体公开本申请的正极极片及其制备方法、包含其的电芯、电池模块、电池包和用电装置，但是会有省略不必要的详细说明的情况。例如，有省略对众所周知的事项的详细说明、实际相同结构的重复说明的情况，这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
为了简明，本申请具体地公开了一些数值范围，各种数值范围可以互相组合，形成相应的实施方案。任意下限可以与任意上限组合形成未明确记载的范围；以及任意下限可以与其他下限组合形成未明确记载的范围，同样任意上限可以与任意其他上限组合形成未明确记载的范围。此外，每个单独公开的点或单个数值自身可以作为下限或上限与任意其他点或单个 数值组合或与其它下限或上限组合形成未明确记载的范围。
除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。在本申请中，除非另有说明，“以上”、“以下”包含本数，例如“a和b中的一种以上”是指a和b中的至少一种，例如a、b，或a和b。同样，“一种或多种”是指包含至少一种。在本文的描述中，除非另有说明，术语“或(or)”是包括性的，也就是说，短语“A或(or)B”表示“A、B，或A和B两者”。
需要说明的是，在本文中，体积平均粒径D50是指待测样品的累计体积分布百分数达到50％时所对应的粒径。在本申请中，体积平均粒径D50可采用激光衍射粒度分析法测定。例如参照标准GB/T 19077-2016，使用激光粒度分析仪(例如Malvern Master Size 3000)进行测定。
需要说明的是，在本申请式(II)的化合物中，m＝(4x+3y+2z)/(4x+4y+4z)表示所述粘结剂中F元素的取代量。
发明人在实际工作中发现，在向锂二次电池正极极片中添加补锂剂时，如果直接将补锂剂添加到正极浆料中，则可能引发正极浆料发生凝胶，从而影响正极浆料的涂布，进而影响二次电池的存储性能和安全性能。为解决上述问题，发明人在进行大量实验后意外发现，通过在正极浆料中包含特定类型的粘结剂，可有效解决正极浆料产生凝胶的问题，从而提高正极浆料的稳定性，进而改善二次电池的存储性能和安全性能。
[正极浆料组合物]
本申请的第一方面提供一种正极浆料组合物，其中，所述组合物中含有正极活性物质、补锂剂和粘结剂，
所述正极活性物质包括式(I)所示的含锂磷酸盐，
LiFe 1-b1-c1Mn b1M 1 c1PO 4      式(I)
其中，0≤b1≤1，0≤c1≤0.1，M 1选自除Fe、Mn外的过渡金属元素以及非过渡金属元素中的至少一种；
所述补锂剂选自Li a1M 2O 0.5(2+a1)、Li 2M 3O 3、Li 2M 4O 4、Li 3M 5O 4、Li 5M 6O 4、Li 5M 7O 6的锂金属氧化物中一种或几种，
其中，a1≥1，M 2选自Ni、Co、Fe、Mn、Zn、Mg、Ca、Cu、Sn中的一种或几种，M 3选自Ni、Co、Fe、Mn、Sn、Cr中的一种或几种，M 4选自Ni、Co、Fe、Mn、Sn、Cr、V、Nb中的一种或几种，M 5选自Ni、Co、Fe、Mn、Sn、Cr、V、Mo、Nb中的一种或几种，M 6选自Ni、Co、Fe、Mn、Sn、Cr、Mo中的一种或几种，M 7选自Ni、Co、Mn中的一种或几种，M 2、M 3、M 4、M 5、M 6、M 7中每种元素的价态分别低于其自身的最高氧化价态；和
所述粘结剂如式(II)所示：
Figure PCTCN2021134474-appb-000002
其中，R 1、R 2彼此独立地为H或F，x、y、z均为正整数，且0.52≤(4x+3y+2z)/(4x+4y+4z)≤0.7。
在式(II)的粘结剂中，m＝(4x+3y+2z)/(4x+4y+4z)代表所述粘结剂中F元素的取代量。可选地，当m过小时，正极浆料中存在大量的H，可能导致粘结剂脱出大量的HF，这一方面可能造成粘结剂失活和正极极片脱模，另一方面可能导致正极浆料产生化学凝胶，从而严重影响产能和二次电池的可靠性。当m过大时，正极浆料中存在大量的F，表明粘结剂中四氟乙烯的含量较多，这可能不利于粘结剂充分发挥其粘结作用，从而改善二次电池的性能。
本申请中，正极浆料组合物由于含有含锂磷酸盐以及补锂剂，补锂剂可以及时补充循环过程中消耗的活性锂，有助于提升含锂磷酸盐类电池的存储性能；与此同时，在正极浆料组合物中添加氟取代量和分子量在一定范围内的粘结剂，可避免由于粘结剂分子链长而造成物理凝胶，还可改善正极浆料组合物的化学凝胶问题，同时，还可以有效控制使用上述正极浆料组合物制成的正极极片，确保正极极片中正极活性物质与补锂剂之间的粘结强度，提升正极极片的可加工性，从而提高电池的存储性能和安全性能。此外，式(II)的粘结剂可以在正极表面造孔，表面孔洞有利于电解液浸润，提升吸液速率，降低电池电阻。
在一些实施方式中，所述补锂剂包括式(III)所示的锂金属氧化物，
Li a2Ni b2Cu 1-b2-c2M 8 c2O 2      式(III)
其中，1<a2＜3，0＜b2＜1，0≤c2＜0.1，M 8选自Zn、Sn、Mg、Fe和Mn中的一种或几种，可选地，1＜a2≤2，0＜b2≤0.6、0.01＜c2＜0.08。
当正极浆料组合物中补锂剂选用式(III)所示的锂金属氧化物时，使用上述正极浆料组合物制成的正极极片具有较高的充电比容量和放电比容量。
发明人发现：当式(III)所示的锂金属氧化物中Cu含量较少时，补锂剂中NiO相对较多，不利于容量的发挥。因此，为达到良好的补锂效果，可选地，式(III)所示的锂金属氧化物中1＜a2≤2，0＜b2≤0.6、0.01＜c2＜0.08。
在一些实施方式中，可选地，所述式(II)的粘结剂的重均分子量为50万至120万。
在本申请第一方面所述的组合物中，当粘结剂的重均分子量为50万至120万时，正极极片可获得良好的可制造性，同时对应二次电池的电化学性能也较好。当粘结剂的重均分子量过大时，其分子链较长，容易造成颗粒团聚，产生物理凝胶。当粘结剂的重均分子量过小时，其分子链较短，可能造成粘结性不足，从而导致极片脱模。
在一些实施方式中，可选地，所述粘结剂在所述组合物中的质量分数为0.2wt％-10wt％，可选地为0.5wt％-4wt％，进一步可选地为1wt％-3.5wt％，更为可选地为1.5wt％-3wt％。
正极活性物质层中包含适量的上述粘结剂，能有效缓解浆料凝胶问题，并且使补锂剂与正极活性物质之间形成较强的粘结作用，使得电池的能量密度和循环寿命均能得到改善。当粘结剂在正极极片中的质量分数过小时，可能导致粘结剂与活性成分和补锂剂之间的粘结不足，造成活性物质和补锂剂脱落，引起安全问题。当粘结剂在正极极片中的质量分数过大时，可能导致极片导电性差，恶化电池阻抗，影响二次电池的动力学性能。
在一些实施方式中，可选地，所述式(II)的粘结剂与所述补锂剂在所述组合物中的质量之比为0.2-2，可选地为0.4-1.5，进一步可选地为0.7-1.0。
虽然机理尚不明确，但发明人意外发现，当补锂剂与粘结剂的质量比在上述范围内时，有利于充分发挥粘结剂的粘结作用，也有利于抑制正极浆料组合物的物理凝胶和化学凝胶，改善二次电池的安全性能和存储性能。
在一些实施方式中，可选地，所述补锂剂在所述组合物中的质量分数为0.1wt％-10wt％，可选地为2wt％-7wt％。
当补锂剂的含量低于上述范围时，可能无法补足正极活性锂的损失。当补锂剂的含量高于上述范围时，可能造成正极可逆嵌锂空位不足，影响电芯的能量密度。
在一些实施方式中，可选地，正极活性材料在本申请所述组合物中的质量分数为80wt％-99.5wt％，可选地为88wt％-96wt％。
在一些实施方式中，可选地，所述补锂剂的体积平均粒径D50为5μm-15μm，所述正极活性材料的体积平均粒径D50为0.5μm-5μm。
本申请中，所述补锂剂的体积平均粒径D50在上述范围内时，具有较快的脱锂速度，有利于弥补低首效引起的容量损失，从而改善电池的循环性能。
在一些实施方式中，可选地，所述补锂剂的pH≤13；可选地，pH≤12.5；进一步可选地，11≤pH≤12.5。
当补锂剂的pH在上述范围内时，有利于进一步降低补锂层浆料发生凝胶的风险，进一步改善补锂效果，从而提升电池的首次充放电容量和循环寿命。由于本申请中使用的补锂剂对水有较高的敏感性，因此当补锂剂的pH过大时，补锂剂的碱性很强，导致补锂剂在吸水之后可能会影响放电克容量，从而不利于提高电池性能。
需要说明的是，补锂剂的pH的测定方法可采用本领域技术人员通常采用的方法，例如滴定法。
在一些实施方式中，可选地，所述补锂剂外侧包覆有单层或多层的包 覆层，所述包覆层包含一种或多种以下材料：金属氟化物、氧化物、金属磷酸盐、锂盐、碳单质、含五元杂环聚合物。
通过对补锂剂外侧包覆上述包覆层，一方面有利于改善申请所述组合物的凝胶问题，另一方面也可有效改善由于补锂剂碱性较强而导致的影响放电克容量发挥的技术问题，从而改善电池的储存性能。
在一些实施方式中，可选地，所述包覆层包含一种或多种以下材料：AlF 3、V 2O 5、Al 2O 3、ZrO 2、TiO 2、ZnO、Co 3O 4、SiO 2、AlPO 4、FePO 4、Co 3(PO 4) 2、Ni 3(PO 4) 2、Li 3PO 4、Li 2MnO 3、LiAlO 2、Li 2TiO 3、Li 2ZrO 3、石墨烯、碳纳米管、聚3,4-乙烯二氧噻吩、聚吡咯。
在一些实施方式中，可选地，所述补锂剂的比表面积为0.5m 2/g-20m 2/g，可选地为1.0m 2/g-19m 2/g，进一步可选地为2m 2/g-18m 2/g，更为可选地5m 2/g-17m 2/g。比表面积的测试可采用本领域通常使用的方法进行，例如可根据标准GB/T19587-2004进行。
通过调控补锂剂的比表面积在上述范围内，可有效及时补充负极消耗的锂离子，保障活性锂数量，从而改善二次电池的容量性能。
在一些实施方式中，可选地，除式(II)所示的粘结剂以外，所述组合物还包括以下物质中的一种或多种作为粘结剂：羧甲基纤维素、羟丙基纤维素、聚丙烯酸、聚偏氟乙烯、聚四氟乙烯、聚乙烯醇、淀粉、聚乙烯吡咯烷酮、聚乙烯、聚丙烯、乙烯-丙烯-丙二烯三元共聚物或磺化的乙烯-丙烯-丙二烯三元共聚物、乙烯-丙烯-丁二烯三元共聚物或磺化的乙烯-丙烯-丁二烯三元共聚物、乙烯-丙烯-戊二烯三元共聚物或磺化的乙烯-丙烯-戊二烯三元共聚物、乙烯-丙烯-己二烯三元共聚物或磺化的乙烯-丙烯-己二烯三元共聚物、苯乙烯丁二烯橡胶、含氟橡胶；和/或，
所述组合物还包括以下物质中的一种或多种作为分散剂：聚丙烯酸钠、十二烷基苯磺酸钠、聚戊烯腈、聚丙烯腈、酚聚氧乙烯醚。
在本申请的正极浆料组合物中加入分散剂，有利于增大孔隙率，降低锂离子迁移阻力，从而降低直流阻抗，改善动力学性能。
在一些实施方式中，可选地，所述分散剂为酚聚氧乙烯醚。
在一些实施方式中，可选地，式(I)所示的正极活性物质包括磷酸铁 锂，以及磷酸亚铁锂、磷酸锰锂、磷酸钛锂、磷酸钴锂、磷酸钒锂中的一种或多种。
[正极极片]
本申请的第二方面提供一种正极极片，其中所述正极极片包括本申请第一方面所述的正极浆料组合物。
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括本申请第一方面的正极浆料组合物。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，可选地，正极膜层还可包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可选地，所述正极浆料组合物在所述正极极片的膜层中的质量分数不低于80％，可选地不低于90％，进一步可选地不低于95％。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、补锂剂、粘结剂、导电剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。
[电解液]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
[二次电池]
本申请第三方面提供一种二次电池，其包括本申请第一方面所述的负极活性材料或通过本申请第二方面所述的正极极片。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
在一些实施方式中，锂离子二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，锂离子二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。锂离子二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)以及聚丁二酸丁二醇酯(PBS)等。
另外，以下适当参照附图对本申请的二次电池、电池模块、电池包和用电装置进行说明。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图5是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图6，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工 艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，锂离子二次电池可以组装成电池模块，电池模块所含锂离子电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图7是作为一个示例的电池模块4。参照图7，在电池模块4中，多个锂离子电池5可以沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个锂离子电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个锂离子电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图8和图9是作为一个示例的电池包1。参照图8和图9，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图10是作为一个示例的用电装置。该用电装置为纯电动车、混合动 力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为本领域通常使用的可以通过市购获得的常规产品。本申请实施例中各成分的含量，如果没有特别说明，均以不含结晶水的干重计。
本申请实施例涉及的原材料来源如下表所示：
Figure PCTCN2021134474-appb-000003
Figure PCTCN2021134474-appb-000004
以下实施例中使用的粘结剂A、粘结剂B、粘结剂C(C1～C6)和分散剂酚聚氧乙烯醚的制备方法如下：
粘结剂A的制备：
向50L高压反应釜内加入20kg去离子水，并抽真空。然后开启搅拌，加入80g 3-烯丙氧基-2-羟基-1-丙磺酸钠(AHPS，以C 6H 11NaO 5S计)。采用隔膜压缩机向反应釜中加入10kg VDF(即1,1-二氟乙烯，以C 2H 2F 2计)单体，加压到设定的反应压力(6MPa)，并搅拌60min。然后加入50g 2,2’-偶氮二异丁腈(AIBN，以C 8H 12N 4计)，并关闭反应釜进料阀门。将反应釜升温至70℃，反应5h。在5h内逐步加入0.9kg乙酸乙酯(每隔1h加20％)，然后加入100g丙酮(纯度99.5％)使反应终止，并回收未反应的单体。对于所得温度为70℃以上的乳液，使用机械搅拌破乳并用去离子水进行洗涤。在测得洗涤水的电导率≤5μs/cm后，将所得乳液放入100℃真空烘箱中干燥24h，所得PVDF树脂即为粘结剂A。
电导率的测试方法如下：参考标准HG/T 4067-2015。使用电导率仪DDSJ-318型，先使用被测样水冲洗电极2～3次，同时进行温度校正，重复取样测定2～3次，测定结果与相对误差均在3％内时，即为最后结果。
粘结剂B的制备：
向50L高压反应釜内加入20kg去离子水，并抽真空。然后开启搅拌，加入80g 3-烯丙氧基-2-羟基-1-丙磺酸钠(AHPS，以C 6H 11NaO 5S计)。采用隔膜压缩机向反应釜中加入9.5kg VDF(即1,1-二氟乙烯，以C 2H 2F 2计)单体和0.5kg丙烯酸(以C 3H 4O 2计)单体，加压到设定的反应压力(8MPa)，并搅拌60min。然后加入50g 2,2'-偶氮二异丁腈(AIBN，以C 8H 12N 4计)，并关闭反应釜进料阀门。将反应釜升温至70℃，反应16h。在16h内逐步加入0.5kg乙酸乙酯(每隔3h加20％)然 后加入100g丙酮(纯度99.5％)使反应终止，并回收未反应的单体。对于所得温度为70℃以上的乳液，使用机械搅拌破乳并用去离子水进行洗涤。在测得洗涤水的电导率≤5μs/cm后，将所得乳液放入100℃真空烘箱中干燥24h，所得PVDF树脂即为粘结剂B。
粘结剂C1的制备：
向50L高压反应釜内加入20kg去离子水，并抽真空。然后开启搅拌，加入80g 3-烯丙氧基-2-羟基-1-丙磺酸钠(AHPS，以C 6H 11NaO 5S计)。采用隔膜压缩机向反应釜中加入7.5kg VDF(即1,1-二氟乙烯，以C 2H 2F 2计)单体和2.5kg TFE(即四氟乙烯，以C 2F 4计)单体，加压到设定的反应压力(6MPa)，并搅拌60min。然后加入50g 2,2'-偶氮二异丁腈(AIBN，以C 8H 12N 4计)，并关闭反应釜进料阀门。将反应釜升温至70℃，反应5h，在5h内逐步加入1.05kg乙酸乙酯(每隔1h加20％)。然后加入100g丙酮(纯度99.5％)使反应终止，并回收未反应的单体。对于所得温度为70℃以上的乳液，使用机械搅拌破乳并用去离子水进行洗涤。在测得洗涤水的电导率≤5μs/cm后，将所得乳液放入100℃真空烘箱中干燥24h，所得PVDF树脂即为粘结剂C1。
粘结剂C2的制备：
向50L高压反应釜内加入20kg去离子水，并抽真空。然后开启搅拌，加入80g 3-烯丙氧基-2-羟基-1-丙磺酸钠(AHPS，以C 6H 11NaO 5S计)。采用隔膜压缩机向反应釜中加入7.5kg VDF(即1,1-二氟乙烯，以C 2H 2F 2计)单体和2.5kg TFE(即四氟乙烯，以C 2F 4计)单体，加压到设定的反应压力(4.2MPa)，并搅拌60min。然后加入50g 2,2'-偶氮二异丁腈(AIBN，以C 8H 12N 4计)，并关闭反应釜进料阀门。将反应釜升温至70℃，反应3h，在3h内逐步加入1.2kg乙酸乙酯(每隔1h加33％)。然后加入100g丙酮(纯度99.5％)使反应终止，并回收未反应的单体。对于所得温度为70℃以上的乳液，使用机械搅拌破乳并用去离子水进行洗涤。在测得洗涤水的电导率≤5μs/cm后，将所得乳液放入100℃真空烘箱中干 燥24h，所得PVDF树脂即为粘结剂C2。
粘结剂C3的制备：
向50L高压反应釜内加入20kg去离子水，并抽真空。然后开启搅拌，加入80g 3-烯丙氧基-2-羟基-1-丙磺酸钠(AHPS，以C 6H 11NaO 5S计)。采用隔膜压缩机向反应釜中加入7.5kg VDF(即1,1-二氟乙烯，以C 2H 2F 2计)单体和2.5kg TFE(即四氟乙烯，以C 2F 4计)单体，加压到设定的反应压力(8MPa)，并搅拌60min。然后加入50g 2,2'-偶氮二异丁腈(AIBN，以C 8H 12N 4计)，并关闭反应釜进料阀门。将反应釜升温至70℃，反应12h，在12h内逐步加入0.7kg乙酸乙酯(每隔2h加20％)。然后加入100g丙酮(纯度99.5％)使反应终止，并回收未反应的单体。对于所得温度为70℃以上的乳液，使用机械搅拌破乳并用去离子水进行洗涤。在测得洗涤水的电导率≤5μs/cm后，将所得乳液放入100℃真空烘箱中干燥24h，所得PVDF树脂即为粘结剂C3。
粘结剂C4的制备：
向50L高压反应釜内加入20kg去离子水，并抽真空。然后开启搅拌，加入80g 3-烯丙氧基-2-羟基-1-丙磺酸钠(AHPS，以C 6H 11NaO 5S计)。采用隔膜压缩机向反应釜中加入7.5kg VDF(即1,1-二氟乙烯，以C 2H 2F 2计)单体和2.5kg TFE(即四氟乙烯，以C 2F 4计)单体，加压到设定的反应压力(8MPa)，并搅拌60min。然后加入50g 2,2'-偶氮二异丁腈(AIBN，以C 8H 12N 4计)，并关闭反应釜进料阀门。将反应釜升温至70℃，反应20h，在20h内逐步加入0.5kg乙酸乙酯(每隔4h加20％)。然后加入100g丙酮(纯度99.5％)使反应终止，并回收未反应的单体。对于所得温度为70℃以上的乳液，使用机械搅拌破乳并用去离子水进行洗涤。在测得洗涤水的电导率≤5μs/cm后，将所得乳液放入100℃真空烘箱中干燥24h，所得PVDF树脂即为粘结剂C4。
粘结剂C5的制备：
向50L高压反应釜内加入20kg去离子水，并抽真空。然后开启搅拌，加入80g 3-烯丙氧基-2-羟基-1-丙磺酸钠(AHPS，以C 6H 11NaO 5S计)。采用隔膜压缩机向反应釜中加入8.6kg VDF(即1,1-二氟乙烯，以C 2H 2F 2计)单体和1.4kg TFE(即四氟乙烯，以C 2F 4计)单体，加压到设定的反应压力(6MPa)，并搅拌60min。然后加入50g 2,2'-偶氮二异丁腈(AIBN，以C 8H 12N 4计)，并关闭反应釜进料阀门。将反应釜升温至70℃，反应5h，在5h内逐步加入1.05kg乙酸乙酯(每隔1h加20％)。然后加入100g丙酮(纯度99.5％)使反应终止，并回收未反应的单体。对于所得温度为70℃以上的乳液，使用机械搅拌破乳并用去离子水进行洗涤。在测得洗涤水的电导率≤5μs/cm后，将所得乳液放入100℃真空烘箱中干燥24h，所得PVDF树脂即为粘结剂C5。
粘结剂C6的制备：
向50L高压反应釜内加入20kg去离子水，并抽真空。然后开启搅拌，加入80g 3-烯丙氧基-2-羟基-1-丙磺酸钠(AHPS，以C 6H 11NaO 5S计)。采用隔膜压缩机向反应釜中加入6.7kg VDF(即1,1-二氟乙烯，以C 2H 2F 2计)单体和3.3kg TFE(即四氟乙烯，以C 2F 4计)单体，加压到设定的反应压力(6MPa)，并搅拌60min。然后加入50g 2,2'-偶氮二异丁腈(AIBN，以C 8H 12N 4计)，并关闭反应釜进料阀门。将反应釜升温至70℃，反应5h，在5h内逐步加入1.05kg乙酸乙酯(每隔1h加20％)。然后加入100g丙酮(纯度99.5％)使反应终止，并回收未反应的单体。对于所得温度为70℃以上的乳液，使用机械搅拌破乳并用去离子水进行洗涤。在测得洗涤水的电导率≤5μs/cm后，将所得乳液放入100℃真空烘箱中干燥24h，所得PVDF树脂即为粘结剂C6。
分散剂酚聚氧乙烯醚的制备：
向50L高压反应釜中加入真空干燥后的10kg十二烷基苄醇(以C 19H 32O计)、1kg甲醇钠(以CH 3ONa计)和10kg环氧乙烷(以C 2H 4O计)，并在加料的同时通入氮气以排出反应釜内的空气。将反应釜加热至 130℃，反应30h，同时开启磁力搅拌。在反应结束后，将反应釜冷却至室温(敞口放置24h)。然后进行称量。反应釜内产品质量基本没有变化，且反应前后物料质量守恒，这表明环氧乙烷完全参与了反应。然后用去离子水对产物进行洗涤，并通过石油醚进行萃取，分离出上层液体。
对比例1
负极极片的制备：将石墨、导电剂乙炔黑、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC)按照质量比96.5重量份：0.7重量份：1.8重量份：1重量份溶于溶剂去离子水中，并充分搅拌混合均匀，得到负极浆料。将负极浆料均匀涂覆在负极集流体铜箔上，经过烘干、冷压、分切得到负极极片。所得负极活性材料层的面密度为9.8mg/cm 2，压实密度为1.65g/cm 3。
正极极片的制备：将活性物质LiFePO 4(LFP)、导电剂乙炔黑、粘结剂A以97重量份：1重量份：2重量份的质量比混合，溶解在溶剂N-甲基吡咯烷酮(即NMP)中，并充分搅拌混合均匀，得到正极浆料。其中活性物质LiFePO 4颗粒的体积平均粒径D50为1.2μm。然后将正极浆料均匀涂覆于铝箔上，经烘干、冷压、分切，得到正极极片。所得正极活性材料层的面密度为19.5mg/cm 2，压实密度为2.4g/cm 3。
电解液的制备：将有机溶剂碳酸亚乙酯(EC)/碳酸甲乙酯(EMC)按照重量比50/50混合均匀，加入LiPF 6溶解于上述有机溶剂中，搅拌均匀，使LiPF 6的浓度为1.1mol/L，得到电解液。
全电池的制备：将上述获得的正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正负极中间起到隔离的作用，并卷绕得到裸电芯。将裸电芯置于外包装中，注入上述电解液并封装，得到全电池(下文也称“全电”)。
对比例2
除在正极极片的制备过程中，将2重量份的活性物质LiFePO 4替换为2重量份的比表面积为16.0m 2/g、体积平均粒径D50为5μm和pH为12.0 的补锂剂Li 2Ni 0.5Cu 0.5O 2(L)以外，对比例2的其他条件与对比例1相同。
对比例3
除在正极极片的制备过程中，将粘结剂A替换为相等质量的粘结剂B以外，对比例3的其他条件与对比例2相同。
实施例1
除在正极极片的制备过程中，将80重量％的粘结剂A(基于总的粘结剂重量计，下同)替换为相等质量的粘结剂C1以外，实施例1的其他条件与对比例2相同。
实施例2
除在正极极片的制备过程中，将50重量％的粘结剂A替换为相等质量的粘结剂C1以外，实施例2的其他条件与对比例2相同。
实施例3
除在正极极片的制备过程中，将20重量％的粘结剂A替换为相等质量的粘结剂C1以外，实施例3的其他条件与对比例2相同。
实施例4
除在正极极片的制备过程中，所使用的补锂剂Li 2Ni 0.5Cu 0.5O 2的比表面积为6.2m 2/g，体积平均粒径D50为11μm，将粘结剂A完全替换为相等质量的粘结剂C1以外，实施例5的其他条件与实施例3相同。
实施例5
除在正极极片的制备过程中，所使用的补锂剂Li 2Ni 0.5Cu 0.5O 2的比表面积为9.7m 2/g，体积平均粒径D50为8μm以外，实施例5的其他条件与实施例4相同。
实施例6-8
实施例6-8除在正极极片的制备过程中，分别将0.05重量份、0.10重量份和0.20重量份的活性物质LiFePO 4替换为相等质量份的分散剂酚聚氧乙烯醚，将粘结剂A完全替换为相等质量的粘结剂C1以外，实施例6-8的其他条件与实施例3相同。
实施例9
除按照以下方法制备正极浆料，并将粘结剂A完全替换为相等质量的粘结剂C1以外，实施例9的其他条件与实施例3相同。
在干混罐中，取2重量份的粘结剂C1与1重量份的导电剂乙炔黑，以1000rpm的转速将它们搅拌混合30min；向搅拌罐中加入N-甲基吡咯烷酮(NMP)，将干混罐中的物料倒入搅拌罐中，以1000rpm的转速搅拌30min；加入95重量份的磷酸铁锂，加入2重量份的补锂剂Li 2Ni 0.5Cu 0.5O 2，以1200rpm的转速搅拌2h，得到正极浆料。
实施例10-13
实施例10-13除在正极极片的制备过程中，分别将0.4重量份、0.8重量份、1.4重量份和3.0重量份的活性物质LiFePO 4替换为相等质量份的补锂剂Li 2Ni 0.5Cu 0.5O 2，并将粘结剂A完全替换为相等质量的粘结剂C1以外，实施例10-13的其他条件与实施例3相同。
实施例14-17
实施例14-17除在正极极片的制备过程中，在正极浆料中加入的补锂剂Li 2Ni 0.5Cu 0.5O 2的pH分别为11.0、12.5、13.0和12.0，并将粘结剂A完全替换为相等质量的粘结剂C1以外，实施例14-17的其他条件与实施例3相同。
实施例18-22
实施例18-22除在正极极片的制备过程中，将粘结剂C1分别替换为相同质量的粘结剂C2、粘结剂C3、粘结剂C4、粘结剂C5和粘结剂C6以外，实施例18-22的其他条件与实施例17相同。
实施例23
实施例23除在正极极片的制备过程中，将补锂剂Li 2Ni 0.5Cu 0.5O 2替换为相等质量的D50为7μm和pH为13.5的补锂剂Li 5FeO 4外，实施例23的其他条件与实施例17相同。
相关参数测试方法
1.补锂剂pH测试参考标准GB/T9724-2007《化学试剂pH值测定通则》
取5g补锂剂加入到45g去离子水中，并以200转/min的转速搅拌30min，然后静置1.5h，得到待测样品。
使用PHS-3S雷磁酸度计进行测定。在常温下(25℃)用纯水冲洗pH电极(E-201-C-pH玻璃复合电极)，将pH电极玻璃球浸没在待测溶液中，稳定30s以上后进行读数。取三次测试的算数平均值作为最终结果。
2.粘结剂的重均分子量测试
通过凝胶渗透色谱法(参考标准：GB/T 21863-2008凝胶渗透色谱法GPC用四氢呋喃做淋洗液)测试粘结剂的重均分子量。
使用N-甲基吡咯烷酮(NMP)配制0.3重量％的待测粘结剂的溶液。取进样瓶量取0.5ml待测粘结剂的溶液，进样量设置在30～100μL。安装好色谱柱与管路，打开色谱仪(Waters e2695)，流动相经过0.45μm的一次性过滤器(除去微粒、不溶性胶、粘结剂等)，并超声脱气。清洗2～4次后进行测试即可获得粘结剂的重均分子量。
3.核磁共振氟含量测试(内标法)
使用核磁共振氟含量测试仪(PQ001，纽迈科技)，开机调整至测试 温度32℃，取标样(已知六氟苯的F含量为n 1＝10％(质量分数))0.3g，放入核磁共振氟含量测试仪，预热十分钟，开始测试，得到核磁共振氟谱信号强度x 1。使用同样的测试方法，测试0.4g、0.5g六氟苯的信号强度，绘制含氟量标准曲线。取待测样品1g，加入9g按照10％质量分数溶解到N-甲基吡咯烷酮中，得到待测溶液。将0.3g待测溶液放入核磁共振氟含量测试仪中，重复三次，得到测试信号强度y 1、y 2和y 3，取三次的平均值计算得到F含量n 2(即m)。
待测样n 2＝n 1*(y 1+y 2+y 3)/3x 1
4.孔隙率测试
采用真密度法(参考GB/T24586-2009)测试孔隙率。先将空的样品杯放入真密度测试仪(AccuPyc II 1340)中，对孔隙率已知的标准样品进行测试以校准设备。然后将极片冲成1.5394cm 2的圆片，数量大于20片，装入样品杯中，再放入仪器中，按照上述标准测得表观密度ρ A和真密度ρ，按照下式进行计算得到样品孔隙率。
孔隙率＝(ρ-ρ A)/ρ*100％
5.吸液速率测试
采用毛细管法测试吸液速率。取2个5cm*5cm的极片，在80℃下干燥4h，之后测试极片厚度。将极片固定在样品台上，使极片的上表面保持在水平方向。挑选内径d＝200μm的毛细管，用500目砂纸打磨至端口齐整。用毛细管吸取电解液，控制毛细管内电解液高度为h＝3mm。将毛细管夹在支架夹子上，使毛细管开口方向与水平方向垂直，调整显微镜镜头倍数至画面清晰，下降毛细管，使其与极片接触，用秒表记录液面开始下降至下降完毕所需的时间t。用毛细管内电解液的质量除以上述时间即得吸液速率：V＝π×(d/2) 2×h×ρ/t，其中ρ为电解液的密度。
测试3次，取平均值计算得到平均吸液速率V。
6.比表面积测试
测试方法参考标准GB/T19587-2004《气体吸附BET法测定固态物质比表面积》。
取样品8～15g装到样品管中，记录样品的初始质量。将称重的样品装入设备NOVA2000e中。然后开始脱气，并将样品加热至200℃后，保持2h。之后记录脱气后样品的质量。然后将脱气后的样品重新装入设备中，倒入液氮进行BET测试。设定氮气压力0.08～0.12MPa，加热温度为40～350℃。测试结束后，从测试结果中读取比表面积。
6.充电比容量和放电比容量测试
在常温(25℃)下以0.33C倍率恒流充电至充电终止电压，再恒压充电至0.05C；测得充电容量Ec0，使用Ec0除以电池正极活性物质质量，即可得到充电比容量。
取上述已完成充电的电池，以0.33C倍率恒流放电至放电终止电压，测得放电容量为Ed0。使用Ed0除以电池正极活性物质质量，即可得到放电比容量。
充电比容量和放电比容量的测试各重复5次，取平均值即得表3中所述充电比容量和放电比容量。
充电比容量(mAh/g)＝第1圈充电容量/正极活性物质质量
放电比容量(mAh/g)＝第1圈放电容量/正极活性物质质量
7.凝胶状况和界面状况
凝胶状况测试：
将烧杯中的新鲜浆料用保鲜膜密封好，
(1).取出静置好的浆料，用手机拍下正面标识及烧杯密封情况。
(2).打开保鲜膜，用钢尺轻轻拨动浆料表面，查看浆料表面是否有异常，颜色是否有变化。
(3).将钢尺慢慢探入到浆料中，上下轻轻移动来初步判断浆料的粘度。按照粘度测试标准DB13/T 5026.1-2019，用粘度测试仪来测量浆料的粘度情况，并记录下数据。
(4).用钢尺舀出部分浆料，查看浆料的流动性，并拍照记录。
观察浆料静置24h后的凝胶状态，针对凝胶状态分为以下等级：
a.轻度凝胶(如图3a)：浆料具有较好的流动性，但液面存在明显反光，并且浆料流下线与液面呈突起。
b.中度凝胶(如图3b)：浆料流动性较差，呈絮状物；浆料类絮状型，但无固体性质；无果冻块状物。
c.严重凝胶(如图3c)：浆料无流动性，呈果冻状；浆料呈现固体性质，无流动性，可以整块挑起。
界面状况测试：
将涂布后的极片，放到电子显微镜CCD(Quantum QLS scope)下，放大50～100倍，观察表面形貌。
8. 50％SOC 4C 10s(第10秒)直流电阻(mΩ)测试
将待测试二次电池在常温下以1C倍率充电至电压为3.65V，然后再以1C倍率放电至电压为2.5V，直接通过仪器读取即可测得可逆容量E0。
将待测试二次电池在常温下以0.33C倍率充电至电压为3.65V，然后再以0.33C倍率放电90min，调整电芯状态到了50％SOC(即有50％电量)，记录此时的电压为U 初始；随后继续以4C倍率放电30秒，记录放电10秒时的电压为U 结束。按下式进行计算得到第10秒时对应的电阻。
DCR＝(U 初始-U 结束)/I
9. 60℃100D存储保持率测试
将待测试二次电池在常温下以1C倍率充电至电压为3.65V，然后再以1C倍率放电至电压为2.5V，直接通过仪器读取即可测得可逆容量E0。再将满充状态的所述二次电池置于60℃烘箱中，每隔20天，将电池取出，立即测试其可逆容量并记为En。
根据下述公式计算电池在60℃下存储前后的容量保持率：ε＝(En-E0)/E0×100％。
表3中的容量保持率是在存储100天后通过上述方法测得的。
10.极片F含量红外光谱测试
取正极极片，使用4mol/L的硫酸在80℃下浸泡2h，过滤后取固体残留物。按照以下方法对固体残留物进行红外光谱测试(参考标准GB/T21186-2007)：取样品粉末1g，隔膜4*4cm 2。取1～2mg样品放入玛瑙研钵中，加入150mg溴化钾样品，研磨15min。研磨后将样品放入模具中，在压片机中压片。在红外测试仪器(光源中红外Ever-Clo光源，分束器KBr/Ge，麦克逊干涉仪，检测器DTGS)中先扫描背景，之后扫描压片样品，波数范围在400～4000cm -1之间。通过红外光谱中1209cm -1和1184cm -1的-CF 2伸缩振动峰，1070cm -1的-CF伸缩振动峰，840cm -1的-CF 2的反对称伸缩振动峰对应的峰面积分别为a1、a2、a3、a4。
取相同质量的三种不同F含量的PVDF标准样品(已知F含量)，按照如上方法测试红外光谱，取对应1209cm -1、1184cm -1、1070cm -1、840cm -1位置的峰面积a绘制标准曲线(官能团含量m＝ka+b)。
将待测样品的红外峰高a1、a2、a3、a4代入标准曲线中，按照公式m＝ka+b计算得到不同单体的含量。
表1 粘结剂A、B以及C1-C6制备过程中的实验条件列表
Figure PCTCN2021134474-appb-000005
表2 实施例1-23以及对比例1-3的实验条件列表
Figure PCTCN2021134474-appb-000006
Figure PCTCN2021134474-appb-000007
表3 实施例1-23以及对比例1-3的测试结果列表
Figure PCTCN2021134474-appb-000008
Figure PCTCN2021134474-appb-000009
从表3中可以看出，实施例1-23的凝胶状况和各项性能相对于对比例1-3均得到明显改善。当式(II)所示粘结剂中氟的取代量在0.5～0.7的范围内时，可显著改善正极浆料的凝胶问题，提高电池的动力学性能和存储保持率。通过进一步调控式(II)所示粘结剂的分子量、用量及其与补锂剂的重量比，以及所述补锂剂的pH、分散剂的用量等参数，可进一步改善凝胶状况，提高电池的存储保持率。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (20)

  1. 一种正极浆料组合物，其中，所述组合物中含有正极活性物质、补锂剂和粘结剂，
    所述正极活性物质包括式(I)所示的含锂磷酸盐，
    LiFe 1-b1-c1Mn b1M 1 c1PO 4  式(I)
    其中，0≤b1≤1，0≤c1≤0.1，M 1选自除Fe、Mn外的过渡金属元素以及非过渡金属元素中的至少一种；
    所述补锂剂选自Li a1M 2O 0.5(2+a1)、Li 2M 3O 3、Li 2M 4O 4、Li 3M 5O 4、Li 5M 6O 4、Li 5M 7O 6的锂金属氧化物中一种或几种，
    其中，a1≥1，M 2选自Ni、Co、Fe、Mn、Zn、Mg、Ca、Cu、Sn中的一种或几种，M 3选自Ni、Co、Fe、Mn、Sn、Cr中的一种或几种，M 4选自Ni、Co、Fe、Mn、Sn、Cr、V、Nb中的一种或几种，M 5选自Ni、Co、Fe、Mn、Sn、Cr、V、Mo、Nb中的一种或几种，M 6选自Ni、Co、Fe、Mn、Sn、Cr、Mo中的一种或几种，M 7选自Ni、Co、Mn中的一种或几种，M 2、M 3、M 4、M 5、M 6、M 7中每种元素的价态分别低于其自身的最高氧化价态；和
    所述粘结剂如式(II)所示：
    Figure PCTCN2021134474-appb-100001
    其中，R 1、R 2彼此独立地为H或F，x、y、z均为正整数，且0.52≤(4x+3y+2z)/(4x+4y+4z)≤0.7。
  2. 根据权利要求1所述的组合物，其中，所述补锂剂至少包括式(III)所示锂金属氧化物，
    Li a2Ni b2Cu 1-b2-c2M 8 c2O 2  式(III)
    其中，1<a2＜3，0＜b2＜1，0≤c2＜0.1，M 8选自Zn、Sn、Mg、Fe和Mn中的一种或几种，可选地，1＜a2≤2，0＜b2≤0.6、0.01＜c2＜0.08。
  3. 根据权利要求1或2所述的组合物，其中，
    所述式(II)的粘结剂的重均分子量为50万至120万。
  4. 根据权利要求1-3中任一项所述的组合物，其中
    所述式(II)的粘结剂在所述组合物中的质量分数为0.2wt％-10wt％，可选地为0.5wt％-4wt％，进一步可选地为1wt％-3.5wt％，更为可选地为1.5wt％-3wt％。
  5. 根据权利要求1-4中任一项所述的组合物，其中，
    所述式(II)的粘结剂与所述补锂剂在所述组合物中的质量之比为0.2-2，可选地为0.4-1.5，进一步可选地为0.7-1.0。
  6. 根据权利要求1-5中任一项所述的组合物，其中，
    所述补锂剂在所述组合物中的质量分数为0.1wt％-10wt％，可选地为2wt％-7wt％。
  7. 根据权利要求1-6中任一项所述的正极极片，其中，
    所述补锂剂的体积平均粒径D50为5μm-15μm，所述正极活性材料的体积平均粒径D50为0.5μm-5μm。
  8. 根据权利要求1-7中任一项所述的组合物，其中，
    所述补锂剂的pH≤13；可选地，pH≤12.5；进一步可选地，11≤pH≤12.5。
  9. 根据权利要求1-8中任一项所述的组合物，其中，
    所述补锂剂外侧包覆有单层或多层的包覆层，所述包覆层包含一种或多种以下材料：金属氟化物、氧化物、金属磷酸盐、锂盐、碳单质、含五 元杂环聚合物。
  10. 根据权利要求9所述的组合物，其中，
    所述包覆层包含一种或多种以下材料：AlF 3、V 2O 5、Al 2O 3、ZrO 2、TiO 2、ZnO、Co 3O 4、SiO 2、AlPO 4、FePO 4、Co 3(PO 4) 2、Ni 3(PO 4) 2、Li 3PO 4、Li 2MnO 3、LiAlO 2、Li 2TiO 3、Li 2ZrO 3、石墨烯、碳纳米管、聚3,4-乙烯二氧噻吩、聚吡咯。
  11. 根据权利要求1-10中任一项所述的组合物，其中，
    所述补锂剂的比表面积为0.5m 2/g-20m 2/g，可选地为1.0m 2/g-19m 2/g，进一步可选地为2m 2/g-18m 2/g，更为可选地5m 2/g-17m 2/g。
  12. 根据权利要求1-11中任一项所述的组合物，其中，
    除式(II)所示的粘结剂以外，所述组合物还包括以下物质中的一种或多种作为粘结剂：羧甲基纤维素、羟丙基纤维素、聚丙烯酸、聚偏氟乙烯、聚四氟乙烯、聚乙烯醇、淀粉、聚乙烯吡咯烷酮、聚乙烯、聚丙烯、乙烯-丙烯-丙二烯三元共聚物或磺化的乙烯-丙烯-丙二烯三元共聚物、乙烯-丙烯-丁二烯三元共聚物或磺化的乙烯-丙烯-丁二烯三元共聚物、乙烯-丙烯-戊二烯三元共聚物或磺化的乙烯-丙烯-戊二烯三元共聚物、乙烯-丙烯-己二烯三元共聚物或磺化的乙烯-丙烯-己二烯三元共聚物、苯乙烯丁二烯橡胶、含氟橡胶；和/或，
    所述组合物还包括以下物质中的一种或多种作为分散剂：聚丙烯酸钠、十二烷基苯磺酸钠、聚戊烯腈、聚丙烯腈、酚聚氧乙烯醚。
  13. 根据权利要求12所述的组合物，其中，所述分散剂为酚聚氧乙烯醚。
  14. 根据权利要求1-13中任一项所述的组合物，其中，所述正极活性物质包括磷酸铁锂，以及磷酸亚铁锂、磷酸锰锂、磷酸钛锂、磷酸钴锂、磷酸钒锂中的一种或多种。
  15. 一种正极极片，其包括根据权利要求1-14中任一项所述的组合物。
  16. 根据权利要求15所述的正极极片，其中
    根据权利要求1-14中任一项所述的组合物在所述正极极片的膜层中的质量分数不低于80％，可选地不低于90％，进一步可选地不低于95％。
  17. 一种二次电池，其中，
    包括如权利要求16所述的正极极片。
  18. 一种电池模块，其包括如权利要求17所述的二次电池。
  19. 一种电池包，其中，包括如权利要求17所述的二次电池或如权利要求18所述的电池模块中的一种以上。
  20. 一种用电装置，其中，
    包括如权利要求17所述的二次电池、如权利要求18所述的电池模块或如权利要求19所述的电池包中的一种以上，所述二次电池或所述电池模组或所述电池包用作所述用电装置的电源或所述用电装置的能量存储单元。
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