WO2022267510A1 - 平板式钠金属电池、电化学装置 - Google Patents

平板式钠金属电池、电化学装置 Download PDF

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Publication number
WO2022267510A1
WO2022267510A1 PCT/CN2022/077901 CN2022077901W WO2022267510A1 WO 2022267510 A1 WO2022267510 A1 WO 2022267510A1 CN 2022077901 W CN2022077901 W CN 2022077901W WO 2022267510 A1 WO2022267510 A1 WO 2022267510A1
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micro
battery
sodium
hole
area
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PCT/CN2022/077901
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English (en)
French (fr)
Inventor
曾毓群
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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 EP22793376.9A priority Critical patent/EP4152462A4/en
Publication of WO2022267510A1 publication Critical patent/WO2022267510A1/zh
Priority to US18/189,309 priority patent/US20230231180A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • 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
    • H01M10/04—Construction or manufacture in general
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/045—Cells or batteries with folded plate-like electrodes
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • 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
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • 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
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/72—Grids
    • H01M4/74—Meshes or woven material; Expanded metal
    • H01M4/742—Meshes or woven material; Expanded metal perforated material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/80—Porous plates, e.g. sintered carriers
    • 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
    • H01M50/233—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by physical properties of casings or racks, e.g. dimensions
    • H01M50/242—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by physical properties of casings or racks, e.g. dimensions adapted for protecting batteries against vibrations, collision impact or swelling
    • 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
    • H01M50/249—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders specially adapted for aircraft or vehicles, e.g. cars or trains
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • 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
    • H01M2004/027—Negative 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
    • 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
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Definitions

  • the present application relates to the technical field of batteries, in particular to a flat sodium metal battery and an electrochemical device.
  • the cruising range of an electric vehicle is directly related to the energy density of the on-board battery pack. Furthermore, it is determined by the energy density of the single battery and its group efficiency (space utilization) in the battery pack.
  • group efficiency of single batteries show a trend towards large capacity/large volume.
  • BYD Company disclosed a new "blade battery" technology, the length of a single battery cell can reach 600mm-2500mm, and the group efficiency of battery packs using blade batteries can be increased from the previous 40%-50% to a maximum of 65%.
  • the energy density of the battery pack has been significantly improved.
  • the enlargement of the battery also brings great challenges to the cell process, such as the consistency of the coating of the large pole pieces, the problem of electrolyte infiltration, the interface control of the positive and negative pole pieces, and the control of defects.
  • sodium-based battery technology with sodium as the core energy storage unit has attracted widespread attention from the industry. So far, sodium-ion batteries have excellent cycle performance and rate performance, and have become one of the powerful alternatives to lithium-ion batteries that are currently widely used.
  • the low energy density of sodium-ion batteries is still a bottleneck limiting its application and promotion.
  • Using metal sodium anode to replace low-capacity sodium ion intercalation/extraction anode can effectively improve the energy density of sodium batteries.
  • the development of sodium-based electrolytes has also effectively controlled the growth of sodium dendrites and the resulting safety issues.
  • Sodium metal batteries have industrial application prospects.
  • the present application provides a flat sodium metal battery and an electrochemical device, which effectively solves the problems of poor coating consistency and difficult wetting in the large pole piece battery, so that the prepared sodium metal battery has both high Energy density, rate performance, cycle efficiency and cost advantages.
  • the embodiment of the present application provides a flat sodium metal battery
  • the battery includes a positive pole piece and a negative pole piece
  • at least part of the surface of the positive pole piece is provided with first micro-through holes arranged in an array
  • At least part of the surface of the negative electrode sheet is provided with second micro-through holes arranged in an array
  • the overlapping area of the first micro-through holes and the second micro-through holes is ⁇ 5% of the total area of the second micro-through holes of the negative electrode sheet.
  • the electrolyte solution evenly infiltrates the battery cell during the battery assembly process, improving the wettability and permeability of the electrolyte solution, thereby realizing the large electrode sheet. Rapid wetting, thereby improving the first Coulombic efficiency and cycle performance of the cell.
  • the electrolyte can also pass through the preset micropores of the positive and negative pole pieces along the vertical direction of the pole pieces and The network formed by the micropores in the separator penetrates quickly, which effectively solves the problem of insufficient electrolyte infiltration of large-size pole pieces.
  • the first micro-vias include at least one of the following technical features:
  • the diameter of the first micro-through hole is 1 ⁇ m to 100 ⁇ m;
  • the distance between the adjacent first micro-through holes is 1 mm to 10 mm;
  • the ratio of the area of the first micro-through hole to the area of the positive electrode sheet is less than 1%.
  • the second micro-vias include at least one of the following technical features:
  • the diameter of the second micro-through hole is 1 ⁇ m to 20 ⁇ m;
  • the distance between the adjacent second micro-through holes is 1 mm to 5 mm;
  • the ratio of the area of the second micro-through hole to the area of the negative electrode sheet is less than 0.1%.
  • the positive pole piece includes a positive active material, and the positive active material is at least one of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds.
  • the negative electrode sheet includes a porous current collector and a conductive coating on at least part of the surface of the porous current collector.
  • the conductive coating includes at least one of the following technical features:
  • the thickness of the conductive coating is 1 ⁇ m to 5 ⁇ m;
  • the ratio of the area of the conductive coating to the pore area of the porous current collector is greater than or equal to 20%;
  • the conductive coating includes a conductive agent and a binder, and the mass percentage content of the conductive agent in the conductive coating is 10% to 80%;
  • the conductive coating includes a conductive agent and a binder, and the conductive agent includes at least one of conductive carbon black, graphite, carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and fullerenes A sort of;
  • the conductive coating includes a conductive agent and a binding agent, and the binding agent is polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, sodium alginate, lithium polyacrylate, sodium polyacrylate, At least one of polytetrafluoroethylene, polyimide, and polyurethane.
  • the battery includes at least one of the following technical features:
  • the battery also includes a separator, which includes a polypropylene microporous film, a polyethylene microporous film, a polyimide microporous film, and a polyethylene terephthalate microporous film. at least one;
  • the battery further includes a separator, and the thickness of the separator is 5 ⁇ m to 15 ⁇ m.
  • the positive pole piece and the negative pole piece are prepared by any one of laser drilling, mechanical punching, or a combination thereof.
  • the cell of the battery is a flat structure
  • the length and width of the cell are both 400 mm to 1600 mm
  • the thickness of the cell is 10 mm to 40 mm
  • the ratio of the length to the width of the cell is (1.1-3.9):1
  • the ratio of the length to the thickness of the cell is (10-150):1.
  • an embodiment of the present application provides an electrochemical device, including the battery described in the first aspect.
  • the application provides the first micro-through hole on the positive pole piece, and the second micro-through hole on the negative pole piece.
  • the size of the micro-through hole aperture and the aperture spacing are set to help increase the infiltration of the electrolyte in the positive pole piece. It is conducive to the rapid infiltration of large-sized pole pieces, and at the same time avoids the problem of insufficient infiltration in the central part due to capillary effect, so that the prepared sodium metal battery has high energy density, rate performance and cycle efficiency. low cost.
  • the battery cell presents a flat plate effect.
  • the battery can be stacked from bottom to top along the thickness direction of the battery, which is beneficial to reduce the battery pack perpendicular to the Vibration and impact in the bottom direction improves the structural stability of the battery/module under working conditions.
  • the application provides a flat sodium metal battery
  • the battery includes at least one of a soft pack, a square aluminum shell, a square steel shell, a cylindrical aluminum shell, and a cylindrical steel shell battery
  • the battery includes a positive pole piece and a negative pole
  • At least part of the surface of the positive electrode sheet is provided with first micro-through holes arranged in an array
  • at least part of the surface of the negative electrode sheet is provided with second micro-through holes arranged in an array.
  • the first micro-through holes and the second The overlapping area of the micro-through holes is greater than or equal to 5% of the total area of the second micro-through holes of the negative electrode sheet.
  • the electrolyte solution evenly infiltrates the battery cell during the battery assembly process, improving the wettability and permeability of the electrolyte solution, thereby realizing the large electrode sheet. Rapid wetting, thereby improving the first Coulombic efficiency and cycle performance of the cell.
  • the electrolyte can also pass through the preset micropores of the positive and negative pole pieces along the vertical direction of the pole pieces and The network formed by the micropores in the separator penetrates quickly, which effectively solves the problem of insufficient electrolyte infiltration of large-size pole pieces.
  • the overlapping area of the first micro through hole and the second micro through hole ⁇ 5% of the total area of the second micro through hole of the negative electrode sheet specifically, the overlapping area of the first micro through hole and the second micro through hole may 5%, 8%, 10%, 15%, 34%, 40%, 50%, 60%, 68%, 70% of the total area of the second micro-through hole of the chip, there is no limit here, and the overlapping area is less than 5% %, the positive pole piece and the negative pole piece cannot permeate well, which affects the speed and efficiency of penetration.
  • the diameter of the first micro through hole is 1 ⁇ m to 100 ⁇ m, specifically, the diameter of the first micro through hole may be 1 ⁇ m, 10 ⁇ m, 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m, 100 ⁇ m, etc., are not limited here.
  • the diameter of the micro-via is less than 1 ⁇ m, it is difficult to precisely control the drilling precision by the drilling technology, and it is difficult to realize; when the diameter of the micro-via is larger than 100 ⁇ m, the loss of active material Many, the capacity of the battery cell decreases significantly, and the material utilization rate decreases at the same time, and the cost increases.
  • the ratio of the area of the micro-through hole to the area of the entire positive electrode sheet is less than 1%.
  • the distance between adjacent first micro through holes is 1 mm to 10 mm.
  • the distance between adjacent first micro through holes may be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10mm, etc., there is no specific limit, and the spacing of the micro-vias is set within the above range to ensure that the large-size pole pieces have sufficient wetting effect after the completion of winding/stacking into dry cells and liquid injection.
  • the surface of the negative electrode current collector of the battery is provided with second micro-through holes arranged in an array, wherein the diameter of the second micro-through holes is 1 ⁇ m to 20 ⁇ m, specifically, the second The aperture of the micro-via can be 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m, 20 ⁇ m, etc., here Without limitation, when the diameter of the second micro-via is less than 1 ⁇ m, it is difficult to accurately control the drilling accuracy of the drilling technology, and it is difficult to realize; when the diameter of the second micro-via is greater than 20 ⁇ m, the positive electrode of the corresponding area of the cell will come out during charging A large amount of sodium will be
  • the ratio of the area of the second micro-through hole to the area of the entire negative electrode sheet is less than 0.1%.
  • the spacing of the second micro-through hole is set between 1mm and 5mm to ensure that the large-size pole piece has sufficient infiltration after winding/stacking into a dry cell and injecting liquid. Effect.
  • by adding a second micro-hole array on the surface of the negative electrode current collector it is beneficial to increase the wettability and permeability of the electrolyte in the negative electrode sheet, which is conducive to the rapid infiltration of the large-size electrode sheet, and at the same time avoids the local area in the middle. Insufficient infiltration of the effect occurs.
  • the positive pole piece and the negative pole piece are prepared by any one of laser drilling, mechanical punching, or a combination thereof.
  • the laser drilling method is preferred to ensure precise control of the hole size.
  • the negative electrode sheet may be directly punched on the current collector and then coated with a conductive coating, or may be punched on the coated current collector. It is preferred to drill the current collector first, and then apply the conductive coating to obtain a better adhesion effect of the conductive coating at the channel. It is enough to ensure that the overlapping area of the first micro-through hole and the second micro-through hole is not less than 5% of the total area of the second micro-through hole of the negative electrode sheet.
  • the positive electrode sheet includes a positive electrode active material, and the positive electrode active material is at least one of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds.
  • the transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce
  • the sodium transition metal oxide is, for example, Na x MO 2 , where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, 0 ⁇ x ⁇ 1.
  • the polyanionic compound includes sodium vanadium trifluorophosphate Na 3 V 2 (PO 4 ) 2 F 3 , sodium vanadium fluorophosphate NaVPO 4 F, sodium vanadium phosphate Na 3 V 2 (PO 4 ) 3 , Na 4 Fe 3 ( One or more of PO 4 ) 2 P 2 O 7 , NaFePO 4 , Na 3 V 2 (PO 4 ) 3 .
  • the Prussian blue compound is NaxM 1 M 2 (CN) 6 , wherein M 1 and M 2 are one or more of Fe, Mn, Co, Ni, Cu, Zn, Cr, Ti, V, Zr, Ce, Wherein, 0 ⁇ x ⁇ 2.
  • a binder and/or a conductive agent may also be added to the positive electrode active material, and the types of the binder and the conductive agent are not limited, and those skilled in the art can select according to actual needs.
  • the above binder can be one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), and styrene-butadiene rubber (SBR),
  • the conductive agent mentioned above can be one or more of graphite, superconducting carbon, acetylene black, carbon black, carbon nanotube, graphene and carbon nanofiber.
  • the negative electrode sheet includes a porous current collector and a conductive coating coated on at least part of the surface of the porous current collector. Since there is no active substance on the surface of the negative electrode, the active sodium is deposited in situ by the first charge of the positive electrode.
  • a conductive coating on the porous current collector By coating a conductive coating on the porous current collector, the active sites on the surface of the electrode sheet can be increased, and the overpotential required for sodium deposition can be reduced. It is conducive to the uniform deposition of sodium on the surface of the negative electrode.
  • the thickness of the conductive coating is 1 ⁇ m to 5 ⁇ m.
  • the thickness of the conductive coating can be 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, etc., without limitation.
  • the thickness of the conductive coating is less than 1 ⁇ m. It is difficult to obtain good uniform coverage and thickness consistency. If the thickness of the conductive coating is greater than 5 ⁇ m, it will cause a certain loss of volumetric energy density.
  • the present application can increase the active sites on the surface of the pole piece by setting a conductive coating on the surface of the porous current collector, reduce the overpotential required for sodium deposition, and facilitate the uniform deposition of sodium on the surface of the negative electrode; further by limiting the area of the conductive coating and The pore area ratio of the porous current collector is ⁇ 20%, which can increase the active sites for sodium deposition in the pores of the pole piece and improve the uniformity of sodium deposition in the pores.
  • the conductive coating includes a conductive agent and a binder
  • the conductive coating includes a conductive agent and a binder
  • the conductive agent includes conductive carbon black, graphite, carbon fiber, single At least one of walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and fullerenes.
  • this application uses single-walled carbon nanotubes as a conductive agent to obtain better conductivity and hole wrapping properties.
  • the binder includes at least one of polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, sodium alginate, lithium polyacrylate, sodium polyacrylate, polytetrafluoroethylene, polyimide, and polyurethane , the binder can increase the adhesion between the conductive coating and the porous current collector, the mass percentage content of the conductive agent in the conductive coating is 10% to 80%, and the content of the conductive agent is controlled within the above range, To ensure that the conductive coating has better conductivity to reduce the overpotential of sodium deposition.
  • the preparation method of the conductive coating is: according to the preset ratio, add the binder and the conductive agent into the solvent water and stir for 6 to 8 hours to obtain a conductive paste.
  • the viscosity of the conductive paste is controlled to be ⁇ 6000mPa ⁇ s
  • the conductive paste is coated on the perforated current collector using a gravure primer and dried to obtain a conductive coating.
  • the battery further includes a separator, which is arranged between the positive electrode sheet and the negative electrode sheet to prevent short-circuiting of the positive and negative electrodes, and the separator includes polypropylene micro At least one of porous film, polyethylene microporous film, polyimide microporous film, polyethylene terephthalate microporous film, the thickness of the isolation film is 5 ⁇ m to 15 ⁇ m, specifically, the isolation The thickness of the film can be 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, etc., which are not limited here. Controlling the thickness within the above range can ensure the insulation and mechanical properties of the isolation film. Strength, and can ensure the rate characteristics and energy density of electrochemical devices.
  • the battery of the present application also includes an electrolyte, which includes sodium salt and an organic solvent.
  • the organic solvent may be an organic solvent commonly used in the electrolytic solution in the art.
  • the organic solvent may be selected from ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, methyl acetate, ethyl propionate, fluoroethylene carbonate , diethyl ether, diglyme, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, methyl tert-butyl ether, preferably ether solvents, used to adjust the deposition of sodium ions Morphology, thereby inhibiting the massive growth of sodium dendrites.
  • the sodium salt in the electrolyte, may be a sodium salt commonly used in the electrolyte in the art.
  • the sodium salt may be selected from sodium hexafluorophosphate, sodium bisfluorosulfonimide, sodium bistrifluoromethanesulfonimide, sodium trifluoromethanesulfonate, sodium tetrafluoroborate, sodium difluorophosphate, perchloric acid at least one of sodium chloride and sodium chloride.
  • the length and width of the battery core are both 400 mm to 1600 mm
  • the thickness of the battery core is 10 mm to 40 mm
  • the ratio of the length to the width of the battery core is (1.1 to 3.9 ): 1
  • the ratio of the length to the thickness of the cell is (10-150): 1.
  • the battery cells present a flat structure.
  • the batteries can be stacked from bottom to top along the battery thickness direction when they are grouped, which is beneficial to reduce the battery pack vertically. Vibration and impact in the bottom direction improves the structural stability of the battery/module under working conditions.
  • the length and width of the battery cells range from 400 to 1600mm, so that the single battery cells and common vehicle battery packs have a reasonable match. Combined with the design requirements of specific electric vehicles, 1 to n pieces can be arranged along the horizontal direction of the battery pack. Flat cells (n ⁇ 6), making the group efficiency of cells as high as possible.
  • the width of the battery less than 1600mm is related to the production and processing width of the existing pole piece coating equipment.
  • the length-to-width ratio setting of the battery is related to the production and processing width of the existing battery pole piece winding equipment, specifically, the size of the winding core.
  • the ratio between the length and thickness of the battery cell is set to limit the thickness of the battery cell to ⁇ 40mm, so as to ensure that the battery cell can effectively dissipate heat along the flat surface, and avoid cycle performance degradation caused by excessive internal temperature rise of the battery cell.
  • the embodiment of the present application also provides an electrochemical device, including the battery described in the first aspect.
  • the electrochemical device of the present application includes any device in which an electrochemical reaction occurs, and its specific examples include all kinds of primary batteries, secondary batteries, fuel cells, solar cells or capacitors, and the electrochemical device is a sodium metal battery.
  • the application of the electrochemical device of the present application is not particularly limited, and it can be used in any electronic device known in the prior art.
  • the electrochemical devices of the present application can be used in, but not limited to, notebook computers, pen-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, head-mounted stereo Headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, Bicycles, lighting appliances, toys, game consoles, clocks, electric tools, flashlights, cameras, large batteries for household use, energy storage and sodium ion capacitors, etc.
  • the full battery is designed and prepared according to the size of the flat cell shell with the length, width and height of 800mm, 400mm and 12mm respectively, so as to further evaluate the technical effect of the application in terms of electrolyte infiltration and electrical performance.
  • the battery design capacity is 512Ah.
  • Positive electrode preparation Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 material was used as positive electrode (gram capacity 120mAh/g), polyvinylidene fluoride (PVdF) was used as binder, conductive carbon black (Super-P ) as a conductive agent, prepared by mixing Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 , PVdF and Super-P in a mass ratio of 96%:2%:2% in N-methylpyrrolidone (NMP) solvent
  • NMP N-methylpyrrolidone
  • Negative electrode preparation a perforated aluminum foil with a thickness of 12 ⁇ m is used as the negative electrode current collector, and a conductive coating is applied on the surface of the negative electrode current collector, and the conductive paste is coated on the perforated current collector by a gravure primer and dried. Obtain the final negative electrode sheet.
  • the prepared cold-pressed pole piece was subjected to laser drilling treatment, and the hole diameter and hole spacing of the negative pole piece of each embodiment are shown in Table 1.
  • Electrolyte preparation NaPF 6 with a concentration of 1 mol/L dissolved in a mixed solvent of diglyme/tetraethylene glycol dimethyl ether at a volume ratio of 1:1 was used as the electrolyte.
  • Example 1 The difference from Example 1 is that the aperture size of the first micro-through hole of the positive electrode is adjusted.
  • Embodiment 1 The difference from Embodiment 1 is that the distance between two first micro-vias adjacent to the positive electrode is adjusted.
  • the difference from the embodiment is that the aperture size of the second micro-through hole of the negative electrode is adjusted.
  • Embodiment 1 The difference from Embodiment 1 is that the distance between two second micro-vias adjacent to the negative electrode is adjusted.
  • Example 1 The difference from Example 1 is that the positive and negative electrodes are not perforated to directly assemble the battery. In order to improve the wetting effect of the electrode piece, the electrolyte injection volume is injected according to the calculated amount of 5g/Ah.
  • Example 1 The difference from Example 1 is that the negative electrode is directly assembled into the battery without punching. In order to improve the wetting effect of the electrode piece, the electrolyte injection volume is calculated as 5g/Ah.
  • Example 1 The difference from Example 1 is that the positive electrode is directly assembled into the battery without perforation treatment. In order to improve the wetting effect of the electrode sheet, the amount of electrolyte injection is calculated as 5g/Ah.
  • Table 1 shows the hole diameter and hole spacing of the positive and negative electrode pieces of each embodiment and comparative example.
  • the charging and discharging voltage is set to 2.5V ⁇ 3.65V
  • the charging and discharging current is set to 512A (1C).
  • Table 2 shows the results of full soaking time, cell capacity and 200-cycle cycle capacity retention rate of the full batteries of each example and comparative example.
  • Example 1 and Comparative Examples 9 to 11 From the comparison of Example 1 and Comparative Examples 9 to 11, it can be seen that the problem of wetting of large-sized flat-plate batteries can be significantly improved by simultaneously punching holes in the positive and negative electrodes.
  • an unperforated pole piece comparative example 9
  • a single positive and negative pole perforated pole piece comparativative examples 10, 11
  • injection coefficient increased from 4.0g/Ah to 5.0g /Ah
  • the battery cell has been left standing for 120 hours, but it still cannot achieve the effect of complete infiltration.
  • the positive and negative pole pieces are perforated, and the electrolyte can be formed through the holes of the pole piece and the separation membrane in addition to the horizontal direction of the pole piece/separator membrane during the process of penetrating into the battery core.
  • the vertical infiltration in the microporous network makes the soaking time of the flat battery significantly shortened, the capacity of the battery cell can be exerted normally, and good cycle stability is maintained.
  • the hole spacing of Examples 6, 1, and 7 and Examples 11, 1, and 12 gradually increase, and the number of holes is more appropriate, which can ensure that the dry cell has a sufficient wetting effect after liquid injection, Improve the cycle performance of the battery cell; within the scope of this application, the pore diameters of the pole pieces of Examples 1 and 2 to 5, 1 and 8 to 10 gradually increase, and the infiltration performance of the sodium metal battery gradually improves, and the pore diameter is set within the above range , can greatly shorten the complete soaking time, ensure that the capacity of the battery cell can be fully utilized and obtain better cycle performance.
  • the hole spacing of Comparative Examples 3 and 7 is smaller than the range value of this application, the hole spacing is smaller, the pole piece contains more holes, and the hole area becomes larger, the complete soaking time of the battery cell is shortened, but the impact on the capacity of the battery cell is also relatively small.
  • the hole spacing of Comparative Examples 4 and 8 is greater than the range value of this application, the number of holes contained in the pole piece gradually decreases, the ability of the micropore network in the battery cell to transport electrolyte decreases, and the complete infiltration of the battery cell Prolonged time will also affect the transmission of local sodium ions, and the cycle performance of the battery will decline to a certain extent.
  • the vertical microporous transmission network of the electrolyte can be constructed by using the perforated positive and negative pole pieces at the same time, which can greatly improve the wetting performance of large-size flat sodium metal batteries, greatly shorten the complete wetting time, and ensure the capacity of the battery cell. Can give full play and obtain better cycle performance.
  • button-type sodium batteries and full batteries with different conductive coatings were prepared.
  • Electrode preparation the negative electrode of the sodium battery is used as the current collector with 12 ⁇ m perforated aluminum foil, and the hole diameter of the perforated holes is 10 ⁇ m, and the hole spacing is 3 mm.
  • the perforated aluminum foil can be prepared by laser drilling or mechanical punching, and the surface of the current collector is coated with a conductive coating.
  • the binder in the conductive coating is styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), the conductive agent is Super-P carbon black, and the ratio of SBR:CMC:Super-P carbon black is 20 %: 20%: 60%.
  • the conductive paste is obtained by adding the binder and the conductive agent into the solvent water and stirring for 6-8 hours, and by controlling the water content, the viscosity of the conductive paste is controlled to be ⁇ 6000mPa ⁇ s, so as to promote the conductive coating to have a higher density in the collector hole area. Large coverage area (the area ratio of conductive agent covered holes is shown in Table 3).
  • the conductive paste was coated on the perforated current collector with a gravure primer and dried to obtain the final negative electrode sheet, and the thickness of the conductive coating was 3 ⁇ m.
  • Button electrical assembly use a puncher to punch the negative pole piece into a small disc with a diameter of 14 mm.
  • a small disc negative electrode In a dry room, assemble a small disc negative electrode, a diaphragm (Celgard2300 model), a sodium sheet (16mm in diameter) and a coin cell case into a coin half cell, and add NaPF6 at a concentration of 1mol/L to dissolve in diethylene glycol diethylene glycol.
  • Methyl ether/tetraethylene glycol dimethyl ether mixed solvent electrolyte with a volume ratio of 1:1, and finally packaged with a button-type packaging machine to obtain a button-type half-cell.
  • Example 13 The difference from Example 13 is that the conductive agent is carbon fiber.
  • Example 13 The difference from Example 13 is that the conductive agent is multi-walled carbon nanotubes.
  • Example 13 The difference from Example 13 is that the conductive agent is single-walled carbon nanotubes.
  • the thickness of the conductive coating was 1 ⁇ m.
  • the thickness of the conductive coating was 5 ⁇ m.
  • Diameter uses perforated aluminum foil as the negative electrode of the battery for button-down preparation.
  • Example 13 The difference from Example 13 is that the viscosity of the conductive paste is less than or equal to 2000 mPa ⁇ s, resulting in a low ratio of the area of the pores covered by the conductive agent in the final perforated negative electrode.
  • the thickness of the conductive coating was 0.5 ⁇ m.
  • the thickness of the conductive coating was 6 ⁇ m.
  • Carbon nanotubes have better electrical conductivity and higher aspect ratio, which is beneficial to increase the coverage of the punched position and reduce the deposition overpotential of the punched position.
  • the viscosity of the slurry is too low and the proportion of the pores covered by the conductive agent is less than 20% (comparative example 13)
  • the deposition overpotential of the button battery is not significantly improved, and the pole piece is prone to uneven sodium deposition, and even dendrites are formed. And more electrochemical side reactions occur with the electrolyte.
  • the thickness of the conductive coating gradually increases, which can effectively reduce the required overpotential for sodium deposition, and when the conductive coating is too thin (comparative example 14), then It is difficult for the conductive coating to cover the entire current collector, resulting in a high local nucleation energy in the uncovered area, and the effect of reducing the overall deposition overpotential is not significant; when the conductive coating is too thick (comparative example 15), it is not conducive to the improvement of the energy density of the cell. promote.
  • Positive electrode preparation Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 material was used as positive electrode (gram capacity 120mAh/g), polyvinylidene fluoride (PVdF) was used as binder, conductive carbon black (Super-P ) as a conductive agent, prepared by mixing Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 , PVdF and Super-P in a mass ratio of 96%:2%:2% in N-methylpyrrolidone (NMP) solvent
  • NMP N-methylpyrrolidone
  • Negative electrode preparation a perforated aluminum foil with a thickness of 12 ⁇ m is used as the negative electrode current collector, and a conductive coating is applied on the surface of the negative electrode current collector, and the conductive paste is coated on the perforated current collector by a gravure primer and dried. Obtain the final negative electrode sheet.
  • the prepared cold-pressed pole piece was subjected to laser drilling treatment, and the hole diameter and hole spacing of the negative pole piece of each embodiment are shown in Table 1.
  • Electrolyte preparation NaPF 6 with a concentration of 1 mol/L dissolved in a mixed solvent of diglyme/tetraethylene glycol dimethyl ether at a volume ratio of 1:1 was used as the electrolyte.
  • Example 19 accounts for 5%
  • Example 1, Example 20, and 21 increase sequentially or arrange according to specific conditions
  • Comparative Example 16 accounts for less than 5%
  • Table 5 shows the results of full soaking time, cell capacity and 200-cycle cycle capacity retention rate of the full batteries of each example and comparative example.
  • the vertical microporous transmission network of the electrolyte can be constructed by using the perforated positive and negative pole pieces at the same time, which can greatly improve the wetting performance of large-size flat sodium metal batteries, greatly shorten the complete wetting time, and ensure the capacity of the battery cell. Can give full play and obtain better cycle performance.

Abstract

提供了一种平板式钠金属电池、电化学装置，电池包括正极极片和负极极片，正极极片至少部分表面设有阵列排布的第一微通孔，负极极片至少部分表面设有阵列排布的第二微通孔，第一微通孔与第二微通孔的重合面积≥负极极片第二微通孔总面积的5％。通过在正极极片上开设第一微通孔，负极极片上开设第二微通孔，通过微通孔孔径大小及孔径间距的设置有利于增加电解液在正极极片中的浸润性及渗透性，有利于大尺寸极片的快速浸润，同时避免中部局部区域因毛细管效应出现的浸润不充分问题，从而使得制备的钠金属电池兼具高的能量密度、倍率性能、循环效率，成本低廉。

Description

平板式钠金属电池、电化学装置
相关申请的交叉引用
本申请要求享有于2021年06月26日提交的名称为“平板式钠金属电池、电化学装置”的中国专利申请202110742606.2的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及电池技术领域，特别是涉及一种平板式钠金属电池、电化学装置。
背景技术
随着电动汽车的日益普及，市场大众对电动汽车的续航里程、快充性能、使用寿命及成本提出了越来越高的要求。其中，电动汽车的续航里程与车载电池包的能量密度直接相关，更进一步，由单体电池的能量密度及其在电池包的成组效率(空间利用率)决定。为进一步提升单体电池的成组效率，单体动力电池呈现出往大容量/大体积发展趋势。例如，2020年比亚迪公司公开了全新“刀片电池”技术，单体电芯长度达600mm～2500mm，使用刀片电池的电池包的成组效率可从之前的40％～50％提升最高至65％，电池包的能量密度获得显著提升。但电池做大也给电芯工艺带来巨大挑战，如大极片的涂敷一致性、电解液浸润问题、正负极极片的界面控制、缺陷控制等。
此外，为进一步降低动力电池及储能电池的资源限制及成本，以钠元素为核心能量存储单元的钠基电池技术受到产业界的广泛关注。发展至 今，钠离子电池具备优异的循环性能及倍率性能，成为目前普遍应用的锂离子电池的有力替代方案之一。但钠离子电池较低的能量密度依旧是限制其应用推广的瓶颈。使用金属钠负极替代低容量的钠离子嵌入/脱出负极可有效提升钠电池的能量密度。与此同时，钠基电解液的发展也使得钠枝晶生长及其导致的安全性问题得到有效控制。钠金属电池具备产业化应用前景。
因此，目前急需一种具有较高能量密度、倍率性能的钠电池，拓宽钠电池在动力电池和储能市场方面的应用。
发明内容
鉴于此，本申请为了克服上述缺陷，提供平板式钠金属电池、电化学装置，有效解决了大极片电池存在的涂敷一致性差、难浸润的问题，使得制备的钠金属电池兼具高的能量密度、倍率性能、循环效率及成本优势。
第一方面，本申请实施例提供一种平板式钠金属电池，所述电池包括正极极片和负极极片，所述正极极片至少部分表面设有阵列排布的第一微通孔，所述负极极片至少部分表面设有阵列排布的第二微通孔，第一微通孔与第二微通孔的重合面积≥负极极片第二微通孔总面积的5％。
在上述技术方案中，通过在正极极片和负极极片上设置微通孔，使得电池在组装过程中，电解液均匀浸润电芯，提高电解液的浸润性和渗透性，从而实现大极片的快速浸润，进而提高电芯的首次库伦效率和循环性能，此时，除沿极片/隔膜水平方向浸润外，电解液同时能够沿极片垂直方向通过正负极极片的预设微孔及隔离膜中的微孔组建的网络中迅速渗透，有效解决了大尺寸极片电解液浸润不充分的难题。
可选地，所述第一微通孔包含如下技术特征中的至少一种：
(1)所述第一微通孔的直径为1μm～100μm；
(2)相邻所述第一微通孔的距离为1mm～10mm；
(3)所述第一微通孔面积与正极极片面积之比＜1％。
可选地，所述第二微通孔包含如下技术特征中的至少一种：
(4)所述第二微通孔的直径为1μm～20μm；
(5)相邻所述第二微通孔的距离为1mm～5mm；
(6)所述第二微通孔面积与负极极片面积之比＜0.1％。
可选地，所述正极极片包括正极活性材料，所述正极活性材料为钠过渡金属氧化物、聚阴离子型化合物、普鲁士蓝类化合物中的至少一种。
可选地，所述负极极片包括多孔集流体及多孔集流体至少部分表面涂覆的导电涂层。
可选地，所述导电涂层包含如下技术特征中的至少一种：
(7)所述导电涂层的厚度为1μm～5μm；
(8)所述导电涂层面积与多孔集流体的孔面积之比≥20％；
(9)所述导电涂层包括导电剂和粘结剂，所述导电剂在所述导电涂层中的质量百分比含量为10％～80％；
(10)所述导电涂层包括导电剂和粘结剂，所述导电剂包括导电碳黑、石墨、碳纤维、单壁碳纳米管、多壁碳纳米管、石墨烯、富勒烯中的至少一种；
(11)所述导电涂层包括导电剂和粘结剂，所述粘结剂为聚偏氟乙烯、羧甲基纤维素钠、丁苯橡胶、海藻酸钠、聚丙烯酸锂、聚丙烯酸钠、聚四氟乙烯、聚酰亚胺、聚胺酯中的至少一种。
可选地，所述电池包含如下技术特征中的至少一种：
(12)所述电池还包括隔离膜，所述隔离膜包括聚丙烯微孔膜、聚乙烯微孔膜、聚酰亚胺微孔膜、聚对苯二甲酸乙二醇酯微孔膜中的至少一种；
(13)所述电池还包括隔离膜，所述隔离膜的厚度为5μm～15μm。
可选地，所述正极极片和负极极片采用激光打孔、机械冲孔中任意一种制备方法或者其组合。
可选地，所述电池的电芯为平板式结构，所述电芯的长度和宽度均为400mm～1600mm，所述电芯的厚度为10mm～40mm，所述电芯的长度与宽度之比为(1.1～3.9)：1，所述电芯的长度与厚度之比为(10～150)：1。
第二方面，本申请实施例提供一种电化学装置，包括第一方面所述的电池。
本申请的有益效果是：
(1)本申请通过在正极极片上开设第一微通孔，负极极片上开设第二微通孔，通过微通孔孔径大小及孔径间距的设置有利于增加电解液在正极极片中的浸润性及渗透性，有利于大尺寸极片的快速浸润，同时避免中部局部区域因毛细管效应出现的浸润不充分问题，从而使得制备的钠金属电池兼具高的能量密度、倍率性能、循环效率，成本低廉。
(2)本申请通过在负极集流体表面设置导电涂层，可增加极片表面的活性位点，降低钠沉积所需的过电势，有利于钠在负极表面的均匀沉积。
(3)本申请通过设置电芯的长度、宽度及厚度设定使得电芯呈现平板式效果，在进行电池成组时可沿电池厚度方向自下而上进行堆叠，有利于降低电池包垂直于底部方向的振动冲击，提升电池/模组在工况下的结构稳定性。
具体实施方式
以下所述是本申请实施例的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本申请实施例原理的前提下，还可以 做出若干改进和润饰，这些改进和润饰也应当视为本申请实施例的保护范围。
在本申请实施例中使用的术语是仅仅出于描述特定实施例的目的，而非旨在限制本申请。在本申请实施例和所附权利要求书中所使用的单数形式的“一种”、“所述”和“该”也旨在包括多数形式，除非上下文清楚地表示其它含义。
本申请提供一种平板式钠金属电池，所述电池包括软包、方形铝壳、方形钢壳、圆柱铝壳和圆柱钢壳电池中的至少一种，所述电池包括正极极片和负极极片，所述正极极片至少部分表面设有阵列排布的第一微通孔，所述负极极片至少部分表面设有阵列排布的第二微通孔，第一微通孔与第二微通孔的重合面积≥负极极片第二微通孔总面积的5％。
在上述技术方案中，通过在正极极片和负极极片上设置微通孔，使得电池在组装过程中，电解液均匀浸润电芯，提高电解液的浸润性和渗透性，从而实现大极片的快速浸润，进而提高电芯的首次库伦效率和循环性能，此时，除沿极片/隔膜水平方向浸润外，电解液同时能够沿极片垂直方向通过正负极极片的预设微孔及隔离膜中的微孔组建的网络中迅速渗透，有效解决了大尺寸极片电解液浸润不充分的难题。第一微通孔与第二微通孔的重合面积≥负极极片第二微通孔总面积的5％，具体地，第一微通孔与第二微通孔的重合面积可以是负极极片第二微通孔总面积的5％、8％、10％、15％、34％、40％、50％、60％、68％、70％等，在此不做限制，重合面积小于5％，正极极片和负极极片不能很好的渗透，影响渗透的速度和效率。
在本申请可选的技术方案中，所述第一微通孔的直径为1μm～100μm，具体地，第一微通孔的直径可以是1μm、10μm、20μm、30μm、40μm、50μm、60μm、70μm、80μm、90μm、100μm等，在此不作 限制，当微通孔直径小于1μm时，打孔技术难以精确控制打孔精度，较难实现；当微通孔直径大于100μm时，活性物质损失过多，电芯的容量下降较为明显，同时物料利用率下降，成本增加，基于此，微通孔的面积与整个正极极片面积之比小于1％。相邻所述第一微通孔的距离为1mm～10mm，具体地，相邻所述第一微通孔的距离可以是1mm、2mm、3mm、4mm、5mm、6mm、7mm、8mm、9mm、10mm等，具体不做限制，将微通孔的间距设置在上述范围内，以保证大尺寸极片在完成卷绕/叠片成干电芯注液后具有充分的浸润效果。本申请通过在正极极片表面添加微通孔阵列，有利于增加电解液在正极极片中的浸润性及渗透性，有利于大尺寸极片的快速浸润，同时避免中部局部区域因毛细管效应出现的浸润不充分问题。
在本申请可选的技术方案中，所述电芯的负极集流体表面设置有阵列排布的第二微通孔，其中，第二微通孔的孔径为1μm～20μm，具体地，第二微通孔的孔径可以是1μm、2μm、3μm、4μm、5μm、6μm、7μm、8μm、9μm、10μm、11μm、12μm、13μm、14μm、15μm、16μm、17μm、18μm、19μm、20μm等，在此不作限制，当第二微通孔直径小于1μm时，打孔技术难以精确控制打孔精度，较难实现；当第二微通孔直径大于20μm时，电芯充电过程中由孔对应区域正极脱出的大量钠会沉积在负极孔壁周围上，造成微孔区域钠沉积的显著不均匀，易形成钠尖端或钠枝晶，导致与电解液的副反应加剧，降低电芯的首次库伦效率及循环性能，严重时存在内短路安全风险。基于此，第二微通孔的面积与整个负极极片面积之比小于0.1％。基于负极集流体打孔孔径上限的限制，第二微通孔的间距设置在1mm～5mm之间，以保证大尺寸极片在完成卷绕/叠片成干电芯注液后具有充分的浸润效果。本申请通过在负极集流体表面添加第二微通孔阵列，有利于增加电解液在负极极片中的浸润性及渗透性，有利于大尺 寸极片的快速浸润，同时避免中部局部区域因毛细管效应出现的浸润不充分问题。
可选地，所述正极极片和负极极片采用激光打孔、机械冲孔中任意一种制备方法或者其组合。优先选用激光打孔方法，以保证孔洞尺寸的精确控制。其中，负极极片可以是直接对集流体打孔再进行导电涂层的涂覆，也可以是对涂覆后的集流体进行打孔处理。优先选用先对集流体打孔，再进行导电涂层的涂敷，以获得孔道处更好的导电涂层附着效果，打孔的方向不作限制，可垂直集流体打孔，还可以倾斜打孔，保证第一微通孔与第二微通孔的重合面积不小于负极极片第二微通孔总面积的5％即可。
在本申请可选的技术方案中，所述正极极片包括正极活性材料，所述正极活性材料为钠过渡金属氧化物、聚阴离子型化合物、普鲁士蓝类化合物中至少一种。所述钠过渡金属氧化物中，过渡金属可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的一种或几种，钠过渡金属氧化物例如为Na xMO 2，其中M为Ti、V、Mn、Co、Ni、Fe、Cr及Cu中的一种或几种，0<x≤1。所述聚阴离子型化合物包括三氟磷酸钒钠Na 3V 2(PO 4) 2F 3、氟磷酸钒钠NaVPO 4F、磷酸钒钠Na 3V 2(PO 4) 3、Na 4Fe 3(PO 4) 2P 2O 7、NaFePO 4、Na 3V 2(PO 4) 3中一种或几种。普鲁士蓝类化合物为NaxM 1M 2(CN) 6，其中，M 1、M 2为Fe、Mn、Co、Ni、Cu、Zn、Cr、Ti、V、Zr、Ce中一种或几种，其中，0＜x≤2。
正极活性物质中还可以添加粘结剂和/或导电剂，对粘结剂、导电剂的种类不加限制，本领域技术人员可根据实际需求进行选择。例如，上述粘结剂可以是聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚丙烯酸(PAA)、聚乙烯醇(PVA)、丁苯橡胶(SBR)中一种或几种，上述导电剂可以是石墨、超导碳、乙炔黑、炭黑、碳纳米管、石墨烯及碳纳米纤 维中的一种或几种。
在本申请可选的技术方案中，所述负极极片包括多孔集流体及多孔集流体至少部分表面涂覆的导电涂层。由于负极表面无活性物质，活性钠通过正极首次充电原位沉积得到，通过在多孔集流体上涂覆导电涂层，可增加极片表面的活性位点，降低钠沉积所需的过电势，有利于钠在负极表面的均匀沉积。所述导电涂层的厚度为1μm～5μm，具体地，所述导电涂层的厚度可以是1μm、2μm、3μm、4μm、5μm等，具体不做限制，导电涂层厚度小于1μm，导电涂层难以获得很好的均匀覆盖性及厚度一致性，若导电涂层厚度大于5μm，则会造成一定体积能量密度的损失。本申请通过在多孔集流体表面设置导电涂层，可增加极片表面的活性位点，降低钠沉积所需的过电势，有利于钠在负极表面的均匀沉积；进一步通过限定导电涂层面积与多孔集流体的孔面积之比≥20％，可增加极片孔道中的钠沉积活性位点，提升钠在孔道中的沉积均匀性。
在本申请可选的技术方案中，所述导电涂层包括导电剂和粘结剂，所述导电涂层包括导电剂和粘结剂，所述导电剂包括导电碳黑、石墨、碳纤维、单壁碳纳米管、多壁碳纳米管、石墨烯、富勒烯中至少一种，优选地，本申请使用单壁碳纳米管作为导电剂，以获得更好的导电性及孔洞包裹性。所述粘结剂包括聚偏氟乙烯、羧甲基纤维素钠、丁苯橡胶、海藻酸钠、聚丙烯酸锂、聚丙烯酸钠、聚四氟乙烯、聚酰亚胺、聚胺酯中的至少一种，粘结剂可以增加导电涂层与多孔集流体的黏合性，所述导电剂在所述导电涂层中的质量百分比含量为10％～80％，将导电剂的含量控制在上述范围内，以保证导电涂层具有更好的导电性，以降低钠沉积过电势。
所述导电涂层的制备方法为：按照预设比将粘结剂、导电剂加入溶剂水中搅拌6～8小时均匀后得到导电浆料，通过控制水含量，导电浆料粘度控制≥6000mPa·s，以促进导电涂层在集流体孔区域有更大面积的覆盖区 域，利用凹版底涂机将导电浆料涂敷于打孔集流体上并烘干，即得到导电涂层。
在本申请可选的技术方案中，所述电池还包括隔离膜，隔离膜设置在正极极片和负极极片之间，起到防止正负极短路的作用，所述隔离膜包括聚丙烯微孔膜、聚乙烯微孔膜、聚酰亚胺微孔膜、聚对苯二甲酸乙二醇酯微孔膜中的至少一种，所述隔离膜的厚度为5μm～15μm，具体地，隔离膜的厚度可以是5μm、6μm、7μm、8μm、9μm、10μm、11μm、12μm、13μm、14μm、15μm等，在此不作限制，将厚度控制在上述范围内，可以确保隔离膜的绝缘性和机械强度，并可以确保电化学装置的倍率特性和能量密度。
进一步地，本申请电池还包括电解液，电解液包括钠盐和有机溶剂。具体地，对电解液中的有机溶剂没有特别的限制，有机溶剂可以是本领域常用的用于电解液的有机溶剂。作为示例，有机溶剂可以选自碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯、碳酸二甲酯、碳酸甲乙酯、碳酸亚丙酯、醋酸甲酯、丙酸乙酯、氟代乙烯碳酸脂、乙醚、二甘醇二甲醚、三乙二醇二甲醚、四乙二醇二甲醚、甲基叔丁基醚中的至少一种，优先选用醚类溶剂，用来调节钠离子沉积形貌，从而抑制钠枝晶的大量生长。在本申请的电化学装置中，对电解液中的钠盐没有特别的限制，钠盐可以是本领域常用的用于电解液的钠盐。作为示例，钠盐可以选自六氟磷酸钠、双氟磺酰亚胺钠、双三氟甲烷磺酰亚胺钠、三氟甲磺酸钠、四氟硼酸钠、二氟磷酸钠、高氯酸钠、氯化钠中的至少一种。
在本申请可选的技术方案中，所述电芯的长度和宽度均为400mm～1600mm，所述电芯的厚度为10mm～40mm，所述电芯的长度与宽度之比为(1.1～3.9)：1，所述电芯的长度与厚度之比为(10～150)：1。根据上述电芯的长度、宽度及厚度设定使得电芯呈现平板式结构，其在电池 组装过程中，电池成组时可沿电池厚度方向自下而上进行堆叠，有利于降低电池包垂直于底部方向的振动冲击，提升电池/模组在工况下的结构稳定性。其中电芯的长度及宽度范围在400～1600mm之间，以使得单体电芯与常用车载电池包具有合理的匹配性，结合特定电动汽车设计要求，能够沿电池包水平方向布置1～n块平板电池(n≤6)，使得电池的成组效率尽可能更高。电池宽度小于1600mm与目前现有极片涂布设备可生产加工幅宽有关。电池的长度与宽度比设定与目前现有电芯极片卷绕设备可生产加工幅宽有关，具体地，与卷芯尺寸有关。所述电芯长度与厚度之比设定将电芯厚度限定在≤40mm，以保证电芯能够沿平板面有效散热，避免电芯内部温升过高导致的循环性能衰退。
本申请实施例还提供一种电化学装置，包括第一方面所述的电池。本申请的电化学装置，包括发生电化学反应的任何装置，它的具体实例包括所有种类的一次电池、二次电池、燃料电池、太阳能电池或电容器，该电化学装置是钠金属电池。本申请的电化学装置的用途没有特别限定，其可用于现有技术中已知的任何电子设备。在一些实施例中，本申请的电化学装置可用于但不限于笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池、储能和钠离子电容器等。
按照长度、宽度及高度分别为800mm、400mm及12mm的平板电芯外壳尺寸设计制备全电池，以进一步评估本申请在电解液浸润及电性能方面的技术效果。其中电芯设计容量为512Ah。
实施例1
(1)正极制备：以Na 4Fe 3(PO 4) 2P 2O 7材料为正极(克容量120mAh/g)，聚偏氟乙烯(PVdF)为粘结剂，导电炭黑(Super-P)为导电剂，将Na 4Fe 3(PO 4) 2P 2O 7、PVdF和Super-P按质量比96％：2％：2％在N-甲基吡咯烷酮(NMP)溶剂中混合均匀制备正极浆料，利用挤压涂布机按正极活性材料单位面积质量30mg/cm 2要求在铝箔表面涂敷正极浆料并烘干，再通过冷压机将涂敷极片以2.5g/cm 3的设计压密进行冷压处理。
(2)负极制备：厚度为12μm打孔铝箔为负极集流体，在负极集流体的表面涂覆导电涂层，利用凹版底涂机将导电浆料涂敷于打孔集流体上并烘干，得到最终负极极片。将制备的冷压极片进行激光打孔处理，各实施例的负极极片打孔孔径及孔间距如表1所示。
(3)电解液制备：采用浓度为1mol/L的NaPF 6溶解于二甘醇二甲醚/四乙二醇二甲醚按体积比1：1的混合溶剂为电解液。
(4)电池装配：将制备好的正负极极片、隔离膜裁剪成相应尺寸通过卷绕机卷绕成干电芯，之后再经过焊接、铝塑膜封装、注液、化成、抽气、二次封装、定容等标准工艺流程制备出软包钠金属电池。其中，电解液注液量按4g/Ah计算量进行注入。
实施例2～5及对比例1～2
与实施例1不同的是，调整正极第一微通孔的孔径大小。
实施例6～7及对比例3～4
与实施例1不同的是，调整正极相邻两个第一微通孔的间距。
实施例8～10及对比例5～6
与实施例不同的是，调整负极第二微通孔的孔径大小。
实施例11～12及对比例7～8
与实施例1不同的是，调整负极相邻两个第二微通孔的间距。
对比例9
与实施例1不同的是，正负极均不进行打孔处理直接装配电池，为提高极片浸润效果，电解液注液量按5g/Ah计算量进行注入。
对比例10
与实施例1不同的是，负极不进行打孔处理直接装配电池，为提高极片浸润效果，电解液注液量按5g/Ah计算量进行注入。
对比例11
与实施例1不同的是，正极不进行打孔处理直接装配电池，为提高极片浸润效果，电解液注液量按5g/Ah计算量进行注入。
将制备的冷压极片进行激光打孔处理，各实施例和对比例正负极极片打孔孔径及孔间距如表1所示。
表1.各实施例和对比例正负极打孔的数据对比
Figure PCTCN2022077901-appb-000001
Figure PCTCN2022077901-appb-000002
性能测试：
(1)电芯电解液浸润性测试方法
将电芯注液后静置不同时间后进行首次充电，按0.1C(51.2A)的电流充电至3.65V，在干燥房中进行拆解，观察负极极片大面区域是否呈现钠沉积后的银白色，如发现底涂暴露的黑色区域则表明浸润不充分，没有则表明完全浸润，记录完全浸润所需的最短时间。按每增加半小时浸润时间设置一个组别，每个组别拆解三个电芯进行判定，三个电芯需同时满足完全浸润标准。
(2)电芯容量及循环性能测试方法
使用电池测试仪对电芯进行充放电测试来评价电芯的电化学性能。其中充放电电压设定为2.5V～3.65V，充放电电流设定为512A(1C)，读取电芯首次充放电及充放电循环200周后从3.65V后放电至2.5V时对应的电芯容量。取三个电芯容量的平均值作为各实施例的电芯容量值。通过以下公式计算电芯的200周循环后的容量保持率：
Figure PCTCN2022077901-appb-000003
各实施例和对比例全电池的完全浸润时间、电芯容量及200周循环容量保持率结果如表2所示。
表2.各实施例和对比例全电池的完全浸润时间、电芯容量及200周循环容量保持率
Figure PCTCN2022077901-appb-000004
Figure PCTCN2022077901-appb-000005
通过实施例1与对比例9～11比较可知，通过在正负极极片同时打孔可以显著改善大尺寸平板电池的浸润问题。使用未打孔极片(对比例9)或单独正、负极打孔极片(对比例10、11)情况下，即便注入更多的电解液(注液系数从4.0g/Ah提高至5.0g/Ah)，电芯静置120小时，仍不能达到完全浸润的效果，局部区域无电解液阻碍了正极中钠的脱出，导致电芯的容量较设计容量显著偏低；同时，也加剧了浸润区/非浸润区交接区域的不均匀钠沉积，电解液的副反应加剧，导致了电芯循环性能也同步下降。而本申请通过对正负极极片进行打孔处理，电解液在向电芯内部渗透过程中除沿极片/隔离膜水平方向外，还可以通过打孔极片与隔离膜的孔组建的微孔网络中进行垂直渗透，使得平板电池的浸润时间显著缩短，电芯的容量得以正常发挥，并保持较好的循环稳定性。
通过实施例1、6、7、11、12和对比例3、4、7和8的对比，可以看出正负极孔间距对电芯完全浸润时间及电性能的影响。通过实施例1、 2～5、8～10和对比例1、2、5、6的对比，可以看出正负极打孔孔径对电芯完全浸润时间及电性能的影响。在本申请的范围内，实施例6、1、7和实施例11、1、12的孔间距逐渐增大，其孔的数量较为合适，能够保证干电芯注液后具有充分的浸润效果，提高电芯的循环性能；在本申请的范围内，实施例1和2～5、1和8～10极片的孔径逐渐增大，钠金属电池的浸润性能逐渐提升，孔径设置在上述范围内，可以大大缩短完全浸润时间，保证电芯的容量能够充分发挥并获得较好的循环性能。对比例3和7的孔间距小于本申请范围值，孔间距较小，极片含的孔较多，孔面积也变大，电芯的完全浸润时间缩短，但对电芯的容量影响也较大，电芯容量偏低，对比例4和8的孔间距大于本申请范围值，极片含的孔数量逐渐减小，电芯中微孔网络输送电解液的能力下降，电芯的完全浸润时间延长，也会影响局部钠离子的传输，电芯的循环性能出现一定下降。当正极及负极的孔径过小时(对比例1、5)，不利于电解液通过孔隙在极片间的渗透及传输，对电芯的浸润改善效果不显著；当正极孔径过大时(对比例2)，则对电芯的能量密度影响较大，同时极片的机械性能下降，在充放电过程中受应力的形变扭曲更大，不利于电芯的循环性能；当负极的孔径过大时(对比例6)，孔道处更难被导电涂层的导电剂覆盖，造成导电孔道周边的不均匀钠沉积加剧，与电解液的副反应增多，同时也存在极片机械性能不足的问题，造成电芯的循环性能下降明显。
综上所述，通过同时使用打孔正负极极片构建电解液的垂直微孔传输网络，可以极大改善大尺寸平板钠金属电池的浸润性能，大大缩短完全浸润时间，保证电芯的容量能够充分发挥并获得较好的循环性能。
为了说明本申请中导电涂层的技术效果，制备了不同导电涂层的扣式钠电池及全电池。
实施例13
(1)极片制备：以钠电池负极均以12μm打孔铝箔为集流体，其中打孔孔径为10μm，孔间距为3mm。打孔铝箔可利用激光打孔或机械冲孔的方式制备，集流体表面涂敷有导电涂层。其中，导电涂层中的粘结剂为丁苯橡胶(SBR)、羧甲基纤维素钠(CMC)，导电剂为Super-P炭黑，SBR：CMC:Super-P炭黑之比为20％：20％：60％。通过将粘结剂、导电剂加入溶剂水中搅拌6～8小时均匀后得到导电浆料，通过控制水含量，导电浆料粘度控制≥6000mPa·s，以促进导电涂层在集流体孔区域有更大面积的覆盖区域(导电剂覆盖孔面积占比如表3所示)。利用凹版底涂机将导电浆料涂敷于打孔集流体上并烘干，得到最终负极极片，导电涂层的厚度为3μm。
(2)扣电装配：利用冲孔器将负极极片冲切为直径为14mm的小圆片。在干燥房中将小圆片负极与隔膜(Celgard2300型号)、钠片(直径16mm)及扣式电池壳装配成扣式半电池，并滴加浓度为1mol/L的NaPF6溶解于二甘醇二甲醚/四乙二醇二甲醚按体积比1：1的混合溶剂的电解液，最终利用扣电封装机封装得到扣式半电池。
实施例14
与实施例13不同的是，导电剂为碳纤维。
实施例15
与实施例13不同的是，导电剂为多壁碳纳米管。
实施例16
与实施例13不同的是，导电剂为单壁碳纳米管。
实施例17
与实施例13不同的是，导电涂层的厚度为1μm。
实施例18
与实施例13不同的是，导电涂层的厚度为5μm。
对比例12
直径使用打孔铝箔作为电池负极进行扣电制备。
对比例13
与实施例13不同的是，导电浆料的粘度≤2000mPa·s，导致最终打孔负极中导电剂覆盖孔面积占比偏低。
对比例14
与实施例13不同的是，导电涂层的厚度为0.5μm。
对比例15
与实施例13不同的是，导电涂层的厚度为6μm。
性能测试：
(1)导电剂覆盖孔面积占比
利用CCD相机对上述实施例/对比例的打孔极片拍照，测量10个打孔点中无导电剂覆盖的面积并计算平均值，通过与标准打孔直径计算得到的打孔面积进行对比，利用如下公式计算得到导电剂覆盖孔面积占比：
Figure PCTCN2022077901-appb-000006
钠沉积过电势的测量方法
使用电池充放电仪对扣电进行放电测试。设置扣式电池的放电电压设置为-100mV vs Na/Na +，电流密度设定为1mA/cm 2，读取容量-电压放电曲线中的电压最低点，即为负极极片钠沉积的过电势，具体数值如表3所示。
表3.各实施例和对比例的导电涂层性能测试
Figure PCTCN2022077901-appb-000007
Figure PCTCN2022077901-appb-000008
由表3可知，通过将对比例12与实施例13～16比较，铝箔表面涂敷有导电涂层后，扣式电池的沉积过电势有明显下降，表明导电涂层更有利于钠的沉积，这与导电涂层有更多的沉积活性位点，降低了钠沉积所需的成核能有关。实施例13～16中导电剂的种类不同，导电剂覆盖孔面积占比及沉积过电势也有所不同，其中实施例16采用单壁碳纳米管为导电剂的沉积过电势最低，这与单壁碳纳米管具有更好的导电性及其更高的长径比有关，有利于增加打孔位置的覆盖度并降低打孔位置的沉积过电势。当浆料粘度过低导致导电剂覆盖孔面积占比＜20％时(对比例13)，扣式电池的沉积过电势改善并不显著，极片容易发生不均匀钠沉积，乃至形成枝晶，并与电解液发生更多的电化学副反应。
在实施例17、13和18中，在本申请的范围内，导电涂层的厚度逐渐增加，可有效降低钠沉积所需的过电势，当导电涂层过薄时(对比例14)，则导电涂层难以覆盖全部集流体，导致未覆盖区域局部的成核能偏 高，降低整体沉积过电势的效果不显著；当导电涂层过厚时(对比例15)，不利于电芯能量密度的提升。
实施例19
(1)正极制备：以Na 4Fe 3(PO 4) 2P 2O 7材料为正极(克容量120mAh/g)，聚偏氟乙烯(PVdF)为粘结剂，导电炭黑(Super-P)为导电剂，将Na 4Fe 3(PO 4) 2P 2O 7、PVdF和Super-P按质量比96％：2％：2％在N-甲基吡咯烷酮(NMP)溶剂中混合均匀制备正极浆料，利用挤压涂布机按正极活性材料单位面积质量30mg/cm 2要求在铝箔表面涂敷正极浆料并烘干，再通过冷压机将涂敷极片以2.5g/cm 3的设计压密进行冷压处理。将制备的冷压极片进行激光打孔处理。
(2)负极制备：厚度为12μm打孔铝箔为负极集流体，在负极集流体的表面涂覆导电涂层，利用凹版底涂机将导电浆料涂敷于打孔集流体上并烘干，得到最终负极极片。将制备的冷压极片进行激光打孔处理，各实施例的负极极片打孔孔径及孔间距如表1所示。
(3)电解液制备：采用浓度为1mol/L的NaPF 6溶解于二甘醇二甲醚/四乙二醇二甲醚按体积比1：1的混合溶剂为电解液。
(4)电池装配：将制备好的正负极极片、隔离膜裁剪成相应尺寸通过卷绕机卷绕成干电芯，之后再经过焊接、铝塑膜封装、注液、化成、抽气、二次封装、定容等标准工艺流程制备出软包钠金属电池。其中，电解液注液量按4g/Ah计算量进行注入。
实施例20～实施例21及对比例16
与实施例19不同的是，调整正负极孔圆心中间距从而改变正极和负极的重合面积，测试结果见表4。(实施例19占比5％、实施例1、实施例20、21依次增大或者根据具体情况排列，对比例16占比小于5％)
各实施例和对比例的正负极极片打孔孔径、孔间距、正极孔与负极 孔的重合面积及重合面积在正极极片孔总面积中占比如表4所示。
表4.各实施例和对比例正极孔与负极孔的重合面积在负极极片孔总面积中占比测试
Figure PCTCN2022077901-appb-000009
各实施例和对比例全电池的完全浸润时间、电芯容量及200周循环容量保持率结果如表5所示。
表5.各实施例和对比例全电池的完全浸润时间、电芯容量及200周循环容量保持率结果
序号 完全浸润时间 电芯容量Ah 200周循环容量保持率
实施例19 15h 509.8 85.20％
实施例20 11h 510.4 86.20％
实施例21 9h 510.7 87.10％
对比例16 87h 509.1 77.80％
由表4可知：通过将实施例19～21与对比例16比较，当正极孔与负极孔的重合面积在负极极片孔总面积中占比≥5％时，重合面积占比越大，平板电池的浸润时间越短，且能够获得较高的电芯容量，并保持较好的循环稳定性。当负极孔与负极孔的重合面积在正极极片孔总面积中占比＜5％时，浸润时间延长，且浸润时间差异较大，导致了电芯循环性能下降。
综上所述，通过同时使用打孔正负极极片构建电解液的垂直微孔传 输网络，可以极大改善大尺寸平板钠金属电池的浸润性能，大大缩短完全浸润时间，保证电芯的容量能够充分发挥并获得较好的循环性能。
以上仅为本申请的较佳实施例而已，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围。

Claims (10)

  1. 一种平板式钠金属电池，包括正极极片和负极极片，所述正极极片至少部分表面设有阵列排布的第一微通孔，所述负极极片至少部分表面设有阵列排布的第二微通孔，第一微通孔与第二微通孔的重合面积≥负极极片第二微通孔总面积的5％。
  2. 根据权利要求1所述的电池，其中，所述第一微通孔包含如下技术特征中的至少一种：
    (1)所述第一微通孔的直径为1μm～100μm；
    (2)相邻所述第一微通孔的距离为1mm～10mm；
    (3)所述第一微通孔面积与正极极片面积之比＜1％。
  3. 根据权利要求1或2所述的电池，其中，所述第二微通孔包含如下技术特征中的至少一种：
    (4)所述第二微通孔的直径为1μm～20μm；
    (5)相邻所述第二微通孔的距离为1mm～5mm；
    (6)所述第二微通孔面积与负极极片面积之比＜0.1％。
  4. 根据权利要求1至3中任一项所述的电池，其中，所述正极极片包括正极活性材料，所述正极活性材料为钠过渡金属氧化物、聚阴离子型化合物、普鲁士蓝类化合物中的至少一种。
  5. 根据权利要求1至4中任一项所述的电池，其中，所述负极极片包括多孔集流体及多孔集流体至少部分表面涂覆的导电涂层。
  6. 根据权利要求5所述的电池，其中，所述导电涂层包含如下技术特征中的至少一种：
    (7)所述导电涂层的厚度为1μm～5μm；
    (8)所述导电涂层面积与多孔集流体的孔面积之比≥20％；
    (9)所述导电涂层包括导电剂和粘结剂，所述导电剂在所述导电涂层中的质量百分比含量为10％～80％；
    (10)所述导电涂层包括导电剂和粘结剂，所述导电剂包括导电碳黑、石墨、碳纤维、单壁碳纳米管、多壁碳纳米管、石墨烯、富勒烯中的至少一种；
    (11)所述导电涂层包括导电剂和粘结剂，所述粘结剂为聚偏氟乙烯、羧甲基纤维素钠、丁苯橡胶、海藻酸钠、聚丙烯酸锂、聚丙烯酸钠、聚四氟乙烯、聚酰亚胺、聚胺酯中的至少一种。
  7. 根据权利要求1至6中任一项所述的电池，其中，所述电池包含如下技术特征中的至少一种：
    (12)所述电池还包括隔离膜，所述隔离膜包括聚丙烯微孔膜、聚乙烯微孔膜、聚酰亚胺微孔膜、聚对苯二甲酸乙二醇酯微孔膜中的至少一种；
    (13)所述电池还包括隔离膜，所述隔离膜的厚度为5μm～15μm。
  8. 根据权利要求1至7中任一项所述的电池，所述正极极片和负极极片采用激光打孔、机械冲孔中任意一种制备方法或者其组合。
  9. 根据权利要求1至8中任一项所述的电池，其中，所述电池的电芯为平板式结构，所述电芯的长度和宽度均为400mm～1600mm，所述电芯的厚度为10mm～40mm，所述电芯的长度与宽度之比为(1.1～3.9)：1，所述电芯的长度与厚度之比为(10～150)：1。
  10. 一种电化学装置，包括权利要求1至9中任一项所述的电池。
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