WO2023216029A1 - 二次电池、电池模组、电池包及用电装置 - Google Patents

二次电池、电池模组、电池包及用电装置 Download PDF

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WO2023216029A1
WO2023216029A1 PCT/CN2022/091479 CN2022091479W WO2023216029A1 WO 2023216029 A1 WO2023216029 A1 WO 2023216029A1 CN 2022091479 W CN2022091479 W CN 2022091479W WO 2023216029 A1 WO2023216029 A1 WO 2023216029A1
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sodium
negative electrode
lithium
secondary battery
electrolyte
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PCT/CN2022/091479
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English (en)
French (fr)
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李小龙
张欣欣
林文光
陈晓霞
刘犇
姚世康
兰加佃
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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 EP22929211.5A priority Critical patent/EP4300648A1/en
Priority to PCT/CN2022/091479 priority patent/WO2023216029A1/zh
Priority to CN202280042527.3A priority patent/CN117501492A/zh
Priority to US18/489,849 priority patent/US20240047756A1/en
Publication of WO2023216029A1 publication Critical patent/WO2023216029A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • 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
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/62—Heating or cooling; Temperature control specially adapted for specific applications
    • H01M10/625—Vehicles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • H01M50/103—Primary casings; Jackets or wrappings characterised by their shape or physical structure prismatic or rectangular
    • 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
    • H01M50/207—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape
    • H01M50/209—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape adapted for prismatic or rectangular cells
    • 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
    • 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

  • This application relates to the field of batteries, specifically to a secondary battery, battery module, battery pack and electrical device.
  • Secondary batteries are widely used in various consumer electronics and electric vehicles due to their outstanding characteristics such as light weight, no pollution, and no memory effect.
  • the present application provides a secondary battery, a battery module, a battery pack and a power device that can improve cycle performance.
  • this application provides a secondary battery, including:
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on the negative electrode current collector, and the negative electrode film layer contains carbon material;
  • a positive electrode sheet including a positive current collector and a positive active material layer disposed on the positive current collector, the positive active material layer containing a sodium ion active material;
  • An electrolyte is provided between the negative electrode piece and the positive electrode piece, and the electrolyte contains sodium salt and lithium salt.
  • the positive active material layer of the positive electrode sheet contains sodium ion active material
  • the negative electrode film layer of the negative electrode sheet contains carbon material
  • the electrolyte contains both sodium salt and lithium salt. Since the electrolyte The lithium ions and sodium ions in the sodium salt and lithium salt are both positive monovalent cations, carrying a unit positive charge, and the lithium ion radius is smaller and has a higher positive charge density, while the carbon material in the negative electrode film itself has Free electrons are relatively easier to absorb lithium ions with higher positive charge density. Therefore, during the charging process of secondary batteries, lithium ions are distributed at the tips of dendrites before sodium ions, which effectively reduces the continued distribution of sodium ions in sodium dendrites. The deposition at the tip forms an effective charge shielding layer, inhibiting the growth of sodium dendrites, thereby greatly improving the cycle performance of the above-mentioned secondary battery.
  • the thickness of the negative electrode film layer is 0.3 ⁇ m ⁇ 3 ⁇ m, and the area density of the negative electrode film layer is 5 g ⁇ 50 g/m 2 .
  • the thickness and surface density of the negative electrode film layer are within the given range, which can further promote the adsorption of lithium ions on the negative electrode film layer and further effectively inhibit the growth of sodium dendrites.
  • the carbon material in the negative electrode film layer includes at least one of carbon nanotubes, graphite, graphene and carbon fiber.
  • the mass content of the lithium salt is 0.1% to 10%.
  • the thickness and surface density of the negative electrode film layer are within the given range, which can further promote the adsorption of lithium ions on the negative electrode film layer and further effectively inhibit the growth of sodium dendrites.
  • x and y satisfy the following conditions: 0.84 ⁇ y-0.01x ⁇ 5.84.
  • the carbon material in the negative electrode film itself has free electrons, it is easier to absorb lithium ions with higher positive charge density, which will cause the effective lithium ion concentration in the electrolyte to decrease. Therefore, as the areal density of the negative electrode film layer containing carbon material increases, the optimal concentration of lithium salt will also increase. Therefore, the lithium salt will have the above-mentioned optimal concentration range depending on the coating surface density of the negative electrode film layer.
  • the lithium salt includes lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium trifluoroacetate, lithium tetraphenylborate, lithium trifluoromethanesulfonate, bisoxaloborate At least one of lithium, lithium difluoroxalate borate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethylsulfonyl)imide.
  • the mass content of the sodium salt in the electrolyte is 3% to 25%;
  • the electrolyte further includes a solvent, and the mass content of the solvent in the electrolyte is 70% to 95%.
  • the sodium salt includes sodium perchlorate, sodium tetrafluoroborate, sodium hexafluorophosphate, sodium hexafluoroarsenate, sodium trifluoroacetate, sodium tetraphenylborate, sodium trifluoromethanesulfonate, At least one of sodium bis(fluorosulfonyl)imide and sodium bis(trifluoromethanesulfonyl)imide;
  • the solvent includes at least one of ether solvents, ester solvents, alkane solvents and sulfone solvents.
  • the solvent includes glycol dimethyl ether, diglyme, triglyme, tetraglyme, 1,3-dioxolane, Ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, carbonic acid Ethyl propyl ester, ⁇ -butyrolactone, 1,3-propane sultone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate, ethyl butyrate and di At least one kind of methyl sulfoxide.
  • the present application provides a battery module, which includes the secondary battery in the above embodiment.
  • the present application provides a battery pack, which includes the battery module in the above embodiment.
  • the present application provides an electrical device, which includes at least one of the secondary battery, battery module and battery pack in the above embodiments, where the secondary battery is used to provide electrical energy.
  • FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .
  • FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 4 .
  • FIG. 6 is a schematic diagram of a power consumption device using a secondary battery as a power source according to an embodiment of the present application.
  • Figure 7 is a graph showing the cycle performance test results of secondary batteries prepared in Examples 1 to 2 and Comparative Examples 1 to 2.
  • Figure 8 is a diagram showing cycle performance test results of secondary batteries prepared in Examples 3 to 4 and Comparative Examples 1 to 2.
  • Figure 9 is a diagram showing cycle performance test results of secondary batteries prepared in Examples 5 to 6 and Comparative Examples 1 to 2.
  • Figure 10 is a diagram showing cycle performance test results of secondary batteries prepared in Examples 7 to 8 and Comparative Examples 1 to 2.
  • Figure 11 is a diagram showing cycle performance test results of secondary batteries prepared in Examples 9 to 10 and Comparative Examples 1 to 2.
  • Figure 12 is a diagram showing cycle performance test results of secondary batteries prepared in Examples 11 to 12 and Comparative Examples 1 to 2.
  • Figure 13 is a diagram showing cycle performance test results of secondary batteries prepared in Examples 13 to 15 and Comparative Examples 1 to 2.
  • Figure 14 is a diagram showing cycle performance test results of secondary batteries prepared in Examples 16-17 and Comparative Examples 1-2.
  • an embodiment means that a particular feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application.
  • the appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art understand, both explicitly and implicitly, that the embodiments described herein may be combined with other embodiments.
  • multiple refers to more than two (including two).
  • multiple groups refers to two or more groups (including two groups), and “multiple pieces” refers to It is more than two pieces (including two pieces).
  • a secondary battery in one embodiment, includes a positive electrode piece, a negative electrode piece and an electrolyte.
  • active ions on the positive electrode plate are embedded and detached back and forth between the positive electrode plate and the negative electrode plate.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on the negative electrode current collector.
  • the negative electrode film layer contains carbon material.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector.
  • the positive electrode active material layer contains sodium ion active material.
  • the electrolyte is located between the negative electrode piece and the positive electrode piece, and the electrolyte contains sodium salt and lithium salt.
  • the active sodium ions on the positive electrode piece are inserted and detached back and forth between the positive electrode piece and the negative electrode piece.
  • the anode will undergo an electrochemical reaction in which sodium ions gain electrons and are reduced to sodium metal.
  • sodium metal is deposited unevenly on the surface of the anode current collector to form dendrites.
  • the tips of the dendrites have a relatively large density due to the tip effect. High negative charge density, which in turn affects the cycle performance of secondary batteries.
  • the positive active material layer of the positive electrode sheet contains sodium ion active material
  • the negative electrode film layer of the negative electrode sheet contains carbon material
  • the electrolyte contains both sodium salt and lithium salt. Since the electrolyte The lithium ions and sodium ions in the sodium salt and lithium salt are both positive monovalent cations, carrying a unit positive charge, and the lithium ion radius is smaller and has a higher positive charge density, while the carbon material in the negative electrode film itself has Free electrons are relatively easier to absorb lithium ions with higher positive charge density. Therefore, during the charging process of secondary batteries, lithium ions are distributed at the tips of dendrites before sodium ions, which effectively reduces the continued distribution of sodium ions in sodium dendrites. The deposition at the tip forms an effective charge shielding layer, inhibiting the growth of sodium dendrites, thereby greatly improving the cycle performance of the above-mentioned secondary battery.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the carbon material in the negative electrode film layer can be a carbon material used in batteries that is well known in the art.
  • the carbon material in the negative electrode film layer includes at least one of carbon nanotubes, graphite, graphene, carbon fiber, mesocarbon microspheres, glassy carbon, soft carbon, and hard carbon.
  • the graphite includes at least one of artificial graphite and natural graphite. Specifically, the graphite can be expanded graphite, highly oriented graphite, three-dimensional graphite, etc. However, this application is not limited to these materials.
  • the carbon material in the negative electrode film layer only one type may be used alone, or two or more types may be used in combination.
  • the carbon material in the negative electrode film layer is at least one of graphite, graphene and carbon fiber.
  • the above-mentioned negative electrode film layer containing carbon material is a carbon material coating.
  • the thickness of the negative electrode film layer containing carbon material is 0.3 ⁇ m to 3 ⁇ m, and the areal density of the negative electrode film layer containing carbon material is 5 g to 50 g/m 2 .
  • the thickness and surface density of the negative electrode film layer are within the given range, which can further promote the adsorption of lithium ions on the negative electrode film layer and further effectively inhibit the growth of sodium dendrites.
  • a binder is optionally included in the negative electrode film layer.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polyacrylic acid sodium (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polyacrylamide At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • a conductive agent is optionally included in the negative electrode film layer.
  • the conductive agent may 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 optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as carbon materials, conductive agents, binders and any other components in a solvent (such as deionized water ), the negative electrode slurry is formed; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode piece can be obtained.
  • a solvent such as deionized water
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode active material layer includes a sodium ion active material, wherein the sodium ion active material serves as the positive electrode active material.
  • the positive electrode current collector has two surfaces opposite in its own thickness direction, and the positive electrode active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode active material may be a cathode active material known in the art for batteries.
  • the sodium ion active material may include at least one of the following materials: at least one of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds.
  • the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials of sodium ion batteries can also be used.
  • the transition metal in the sodium transition metal oxide, can be at least one 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 may be a type of compound having sodium ions, transition metal ions and tetrahedral (YO 4 ) n- anion units.
  • the transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce;
  • Y can be at least one of P, S and Si;
  • n represents (YO 4 ) n -valency.
  • Polyanionic compounds may also be compounds having sodium ions, transition metal ions, tetrahedral (YO 4 ) n- anion units and halogen anions.
  • the transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce;
  • Y can be at least one of P, S and Si, n represents (YO 4 )
  • the valence state of n- ; the halogen can be at least one of F, Cl and Br.
  • Polyanionic compounds may also be a class of compounds having sodium ions, tetrahedral (YO 4 ) n- anion units, polyhedral units (ZO y ) m+ , and optionally halogen anions.
  • Y can be at least one of P, S and Si
  • n represents the valence state of (YO 4 ) n-
  • Z represents a transition metal, which can be Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V , Zr and Ce
  • m represents the valence state of (ZO y ) m+
  • the halogen can be at least one of F, Cl and Br.
  • polyanionic compounds are NaFePO 4 , Na 3 V 2 (PO4) 3 (sodium vanadium phosphate, NVP for short), Na 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ), NaM'PO4F (M' is V , Fe, Mn and Ni) and at least one of Na 3 (VO y ) 2 (PO 4 ) 2 F 3-2y (0 ⁇ y ⁇ 1).
  • Prussian blue compounds may be compounds containing sodium ions, transition metal ions and cyanide ions (CN - ).
  • the transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce.
  • the Prussian blue compound is, for example, Na a Me b Me' c (CN) 6 , where Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 ⁇ a ⁇ 2, 0 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 1.
  • a binder is optionally included in the positive active material layer.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • a conductive agent is optionally included in the cathode active material layer.
  • 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 positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as sodium ion active material, conductive agent, binder and any other components in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode piece can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the type of electrolyte in this application can be selected according to needs.
  • the electrolyte can be liquid, gel, or completely solid.
  • the mass content of the lithium salt is 0.1% to 10%.
  • controlling the lithium salt in the electrolyte within a given range can enable lithium ions to form an effective charge shielding layer on the surface of the negative electrode, thus inhibiting the growth of sodium dendrites.
  • it can avoid the problem that the lithium ion concentration is too high, causing the density of lithium ions on the surface of the negative electrode current collector to be too high, thereby increasing the overpotential of sodium metal deposition.
  • the mass content of the lithium salt can be 0.1%, 0.2%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%. Further, based on the mass of the electrolyte, the mass content of the lithium salt can be 0.5% to 5%, 0.5% to 2%, or 0.5% to 1%.
  • the carbon material in the negative electrode film itself has free electrons, it is easier to absorb lithium ions with higher positive charge density, which will cause the effective lithium ion concentration in the electrolyte to decrease. Therefore, as the areal density of the negative electrode film layer containing carbon material increases, the optimal concentration of lithium salt will also increase. Therefore, the lithium salt will have the following optimal concentration range depending on the coating surface density of the negative electrode film layer.
  • x and y satisfy the following conditions: 0.84 ⁇ y-0.01x ⁇ 5.84.
  • the thickness of the negative electrode film layer containing carbon material is 0.3 ⁇ m to 3 ⁇ m.
  • lithium salts include lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium trifluoroacetate (CF 3 COOLi), lithium tetraphenylborate (LiB(C 6 H 5 ) 4 ), lithium trifluoromethanesulfonate (LiSO 3 CF 3 ), lithium bisoxaloborate (LiBOB), lithium difluorooxalate borate (LiDFOB), bis At least one of lithium (fluorosulfonyl)imide (Li[(FSO 2 ) 2 N]) and lithium bis(trifluoromethylsulfonyl)imide (Li[(CF 3 SO 2 ) 2 N]) .
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium perchlorate
  • the mass content of sodium salt in the electrolyte is 3% to 25%.
  • sodium salts include sodium perchlorate (NaClO 4 ), sodium tetrafluoroborate (NaBF 4 ), sodium hexafluorophosphate (NaPF 6 ), sodium hexafluoroarsenate (NaAsF 6 ), sodium trifluoroacetate (CF 3 COONa), sodium tetraphenylborate (NaB(C 6 H 5 ) 4 ), sodium triflate (NaSO 3 CF 3 ), sodium bis(fluorosulfonyl)imide (Na[(FSO 2 ) 2 N]) and sodium bis(trifluoromethanesulfonyl)imide (Na[(CF 3 SO 2 ) 2 N]).
  • the electrolyte is an electrolyte solution.
  • the electrolyte also includes a solvent.
  • the mass content of the solvent in the electrolyte ranges from 70% to 95%.
  • the mass content of the solvent in the electrolyte is 70% to 95%; the mass content of the sodium salt is 3% to 25%; and the mass ratio of the lithium salt to the electrolyte is 0.1% to 10%.
  • the solvent includes at least one of ether solvents, ester solvents, alkane solvents and sulfone solvents.
  • solvents include glycol dimethyl ether, diglyme, triglyme, tetraglyme, 1,3-dioxolane, ethylene carbonate , propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate , ⁇ -butyrolactone, 1,3-propane sultone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate, ethyl butyrate and dimethyl sulfide At least one of the sulfones.
  • the electrolyte optionally further includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • the secondary battery further includes a separator film.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows ions to pass through.
  • isolation membrane there is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 1 shows a square-structured secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into 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.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery module.
  • FIG. 3 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space in which a plurality of secondary batteries 5 are received.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number 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 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 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 electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided by the present application.
  • the secondary battery, battery module, or battery pack may be used as a power source for the electrical device, or may be used as an energy storage unit for the electrical device.
  • the electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, and electric golf carts). , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.
  • FIG. 6 is an electrical device as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • the device may be a mobile phone, a tablet, a laptop, etc.
  • the device is usually required to be thin and light, and a secondary battery can be used as a power source.
  • a carbon nanotube aqueous solution with a concentration of 1wt% (containing 0.05wt% CMC-Na) is dispersed on the negative electrode current collector with a scraper, and then dried, cold pressed, and cut to obtain a carbon nanotube base coating. Negative pole piece.
  • NMP N-methylpyrrolidone
  • the obtained laminated battery was placed in a drying oven under vacuum conditions of 85°C for 12 hours, and the dried battery was taken out.
  • the battery temperature is cooled to room temperature, inject the electrolyte prepared in step (1) into the battery.
  • the injection volume is 0.5g.
  • the injection port is heat-sealed. Then put a clamp on the packaged battery core and apply appropriate pressure on both ends of the clamp to complete the assembly of the stacked battery.
  • the assembled laminated battery is then subjected to formation treatment.
  • the specific formation steps are as follows: at 25 ⁇ 3°C, charge with a constant current of 0.1C (2.4mA) to 3.5V, and then discharge with a constant current of 0.1C to 3.2V. , and then perform a cycle performance test; the specific cycle test steps are as follows: charge with a constant current at a rate of 1C (24mA) to 3.5V, then discharge with a constant current at a rate of 1C to 3.2V, and then repeat the constant current charge and discharge cycle operation at 1C to obtain Capacity retention rate after 500 cycles.
  • the electrolyte composition (all mass ratios), primer carbon material, primer thickness, primer area density, positive electrode active material and 500-cycle capacity retention rate of the prepared battery used in each example and comparative example are as follows: 1 shows:
  • Examples 5 and 6 the difference between Examples 5 and 6 compared to Examples 1 and 2 is that the electrolyte solvent is replaced by the type of solvent in the electrolyte in Examples 1 and 2. Specifically, ethylene glycol is used. Diethylene glycol dimethyl ether (DME) is replaced by diethylene glycol dimethyl ether (DEGDME). The two solvents are similar substances and have little difference in chemical properties. Similarly, compared with Comparative Examples 1 and 2, the capacity retention rate of Examples 5 and 6 reaches approximately 91%. It shows that the electrolyte formula can also effectively improve the battery cycle performance.
  • DME diethylene glycol dimethyl ether
  • DEGDME diethylene glycol dimethyl ether
  • Examples 7 and 8 compared to Examples 3 and 4 is that the electrolyte solvent is replaced by the type of solvent in the electrolyte in Examples 3 and 4. Specifically, ethylene glycol is used. Diethylene glycol dimethyl ether (DME) is replaced by diethylene glycol dimethyl ether (DEGDME). The two solvents are similar substances and have little difference in chemical properties. Similarly, compared to Comparative Examples 1 to 2, the capacity retention rate of Examples 7 to 8 reaches about 91%. It shows that the electrolyte formula can also effectively improve the battery cycle performance.
  • DME diethylene glycol dimethyl ether
  • DEGDME diethylene glycol dimethyl ether
  • Examples 9 to 10 are respectively the minimum boundary value and the boundary value of the mass content range of lithium salt in the electrolyte calculated through the surface density of the primer according to 0.84 ⁇ y-0.01x ⁇ 5.84 external value. It can be seen that the capacity retention rate of Example 9 after 500 cycles is 88.9%, which has better battery cycle performance than Comparative Examples 1 to 2.
  • the mass content of the lithium salt in the electrolyte of Example 10 is lower than the minimum boundary value of the above-mentioned mass content range, that is, it is a value outside the boundary of the above-mentioned mass content range. It can be seen that the capacity retention rate of Example 10 is compared with that of Example 10. 9 has decreased.
  • Examples 11 and 12 are respectively the maximum boundary value of the mass content range of the lithium salt in the electrolyte calculated from the surface density of the primer based on 0.84 ⁇ y-0.01x ⁇ 5.84 with values outside the bounds. It can be seen that the capacity retention rate of Example 11 after 500 cycles is 87.1%, which has better battery cycle performance than Comparative Examples 1 to 2.
  • the mass content of the lithium salt in the electrolyte of Example 12 is higher than the maximum boundary value of the above-mentioned mass content range, that is, the value outside the boundary of the above-mentioned mass content range. It can be seen that the capacity retention rate of Example 12 is only 85.4%, which is relatively low. Compared with Example 11, the optimization effect is not obvious.
  • Example 15 is within the mass content range of the lithium salt in the electrolyte calculated by the surface density of the primer based on 0.84 ⁇ y-0.01x ⁇ 5.84. value.
  • the mass content of lithium salt in Examples 13 to 14 is outside the calculated range.
  • the capacity retention rate of Example 15 is better than that of Examples 13-14.
  • the difference mainly lies in the content of the lithium salt.
  • the mass content of the lithium salt in the electrolyte is 0.5% to 1%.
  • Example 1 As shown in Figure 14 and Table 1, among Example 1 and Examples 16 to 18, the capacity retention rate of Examples 16 to 18 is better than that of Example 1, and Example 18 is better than Example 17, and even better than Example 17. 16.
  • the type of carbon material is more preferably carbon fiber, graphene or graphite.

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Abstract

本发明涉及一种二次电池、电池模组、电池包及用电装置。其中，该二次电池包括：负极极片，包括负极集流体及设于所述负极集流体上的负极膜层，所述负极膜层含有碳材料；正极极片，包括正极集流体及设于所述正极集流体上的正极活性材料层，所述正极活性材料层中含有钠离子活性材料；及电解质，设于所述负极极片与所述正极极片之间，所述电解质中包含有钠盐和锂盐。

Description

二次电池、电池模组、电池包及用电装置 技术领域
本申请涉及电池领域，具体涉及一种二次电池、电池模组、电池包及用电装置。
背景技术
二次电池因具有重量轻、无污染、无记忆效应等突出特点，被广泛应用于各类消费类电子产品和电动车辆中。
随着新能源行业的不断发展，客户对二次电池提出了更高的使用需求。锂资源的价格持续上涨，进一步增加了当前动力电池成本，极大地限制了其应用。钠与锂的物理和化学性质非常相似，并且钠在地球上的丰度远高于锂，且成本更低，因而发展含有钠离子活性材料的钠离子电池是解决当前动力电池高成本问题的有效手段。
然而在实际生产中发现，目前的钠离子电池存在循环性能差等问题。
发明内容
鉴于上述问题，本申请提供一种能够改善循环性能的二次电池、电池模组、电池包及用电装置。
第一方面，本申请提供了一种二次电池，包括：
负极极片，包括负极集流体及设于所述负极集流体上的负极膜层，所述负极膜层含有碳材料；
正极极片，包括正极集流体及设于所述正极集流体上的正极活性材料层，所述正极活性材料层中含有钠离子活性材料；及
电解质，设于所述负极极片与所述正极极片之间，所述电解质中包含有钠盐和锂盐。
本申请上述实施方式的技术方案中，正极极片的正极活性材料层中含有钠离子活性材料，且负极极片的负极膜层含有碳材料及电解质中同时包含有钠盐和锂盐，由于电解质的钠盐和锂盐中的锂离子与钠离子均为正一价阳离子，带一个单位正电荷，且锂离子半径更小具有更高的正电荷密度， 而负极膜层中上碳材料本身具有自由电子，相对更容易吸附正电荷密度较高的锂离子，故而在二次电池的充电过程中，使得锂离子先于钠离子在枝晶尖端分布，有效地降低了钠离子继续在钠枝晶尖端处的沉积形成有效的电荷屏蔽层，抑制了钠枝晶生长，进而极大地提升了上述二次电池的循环性能。
在一些实施例中，所述负极膜层的厚度为0.3μm～3μm，所述负极膜层的面密度为5g～50g/m 2。该负极膜层的厚度和面密度在所给定范围，可进一步促使锂离子在负极膜层上吸附，进一步有效地抑制了钠枝晶生长。
在一些实施例中，所述负极膜层中的碳材料包括碳纳米管、石墨、石墨烯和碳纤维中的至少一种。
在一些实施例中，以所述电解质的质量为基准，所述锂盐的质量含量为0.1％～10％。该负极膜层的厚度和面密度在所给定范围，可进一步促使锂离子在负极膜层上吸附，进一步有效地抑制了钠枝晶生长。
在一些实施例中，所述负极膜层的面密度为x g/m 2，x＝5g～50g/m 2；以所述电解质的质量为基准，所述锂盐的质量含量为y％；
x和y满足如下条件：0.84≤y-0.01x≤5.84。
同时考虑到负极膜层中的碳材料本身有自由电子，比较容易吸附正电荷密度较高的锂离子，这将会造成电解质中有效的锂离子浓度降低。因而随着该含有碳材料的负极膜层的面密度增加，锂盐的最优浓度也会增加。故而，锂盐会随底该负极膜层的涂布面密度存在上述最优浓度范围。
在一些实施例中，所述锂盐包括六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、三氟乙酸锂、四苯硼酸锂、三氟甲基磺酸锂、双草酸硼酸锂、二氟草酸硼酸锂、双(氟磺酰)亚胺锂及双(三氟甲基磺酰)亚胺锂中的至少一种。
在一些实施例中，所述电解质中，所述钠盐的质量含量为3％～25％；
和/或，所述电解质中还包括溶剂，所述电解质中所述溶剂的质量含量为70％～95％。
在一些实施例中，所述钠盐包括高氯酸钠、四氟硼酸钠、六氟磷酸钠、六氟砷酸钠、三氟乙酸钠、四苯硼酸钠、三氟甲基磺酸钠、双(氟磺酰)亚胺钠和双(三氟甲基磺酰)亚胺钠中的至少一种；
和/或，所述溶剂包括醚类溶剂、酯类溶剂、烷烃类溶剂及砜类溶剂中的至少一种。
在一些实施例中，所述溶剂包括乙二醇二甲醚、二乙二醇二甲醚、三乙二醇二甲醚、四乙二醇二甲醚、1,3-二氧戊环、碳酸乙烯酯、碳酸丙烯酯、碳酸丁烯酯、碳酸亚乙烯酯、氟代碳酸乙烯酯、碳酸甲乙酯、碳酸二甲酯、碳酸二乙酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、γ-丁内酯、1,3-丙烷磺酸内酯、丙酸甲酯、丁酸甲酯、乙酸乙酯、丙酸乙酯、丙酸丙酯、丁酸乙酯及二甲基亚砜中的至少一种。
第二方面，本申请提供了一种电池模组，其包括上述实施例中的二次电池。
第三方面，本申请提供了一种电池包，其包括上述实施例中的电池模组。
第四方面，本申请提供了一种用电装置，其包括上述实施例中的二次电池、电池模组和电池包中的至少一种，所述二次电池用于提供电能。
上述说明仅是本申请技术方案的概述，为了能够更清楚了解本申请的技术手段，而可依照说明书的内容予以实施，并且为了让本申请的上述和其它目的、特征和优点能够更明显易懂，以下特举本申请的具体实施方式。
附图说明
通过阅读对下文优选实施方式的详细描述，各种其他的优点和益处对于本领域普通技术人员将变得清楚明了。附图仅用于示出优选实施方式的目的，而并不认为是对本申请的限制。而且在全部附图中，用相同的附图标号表示相同的部件。在附图中：
图1是本申请一实施方式的二次电池的示意图。
图2是图1所示的本申请一实施方式的二次电池的分解图。
图3是本申请一实施方式的电池模块的示意图。
图4是本申请一实施方式的电池包的示意图。
图5是图4所示的本申请一实施方式的电池包的分解图。
图6是本申请一实施方式的二次电池用作电源的用电装置的示意图。
图7为实施例1～2及对比例1～2制得的二次电池的循环性能测试结果 图。
图8为实施例3～4及对比例1～2制得的二次电池的循环性能测试结果图。
图9为实施例5～6及对比例1～2制得的二次电池的循环性能测试结果图。
图10为实施例7～8及对比例1～2制得的二次电池的循环性能测试结果图。
图11为实施例9～10及对比例1～2制得的二次电池的循环性能测试结果图。
图12为实施例11～12及对比例1～2制得的二次电池的循环性能测试结果图。
图13为实施例13～15及对比例1～2制得的二次电池的循环性能测试结果图。
图14为实施例16～17及对比例1～2制得的二次电池的循环性能测试结果图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53盖板。
具体实施方式
下面将结合附图对本申请技术方案的实施例进行详细的描述。以下实施例仅用于更加清楚地说明本申请的技术方案，因此只作为示例，而不能以此来限制本申请的保护范围。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同；本文中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。
在本申请实施例的描述中，技术术语“第一”“第二”等仅用于区别不同对象，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特 征的数量、特定顺序或主次关系。在本申请实施例的描述中，“多个”的含义是两个以上，除非另有明确具体的限定。
在本文中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。本领域技术人员显式地和隐式地理解的是，本文所描述的实施例可以与其它实施例相结合。
在本申请实施例的描述中，术语“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
在本申请实施例的描述中，术语“多个”指的是两个以上(包括两个)，同理，“多组”指的是两组以上(包括两组)，“多片”指的是两片以上(包括两片)。
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。
本申请的一个实施方式中，提供一种二次电池。该二次电池包括正极极片、负极极片和电解质。在电池充放电过程中，正极极片上的活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。
其中，负极极片包括负极集流体及设于负极集流体上的负极膜层，负极膜层中含有碳材料。正极极片包括正极集流体及设于正极集流体上的正极活性材料层，正极活性材料层中含有钠离子活性材料。电解质设于负极极片与正极极片之间，电解质中包含有钠盐和锂盐。
一般地，正极极片上的活性钠离子在正极极片和负极极片之间往返嵌入和脱出。如此在二次电池的充电过程中，负极将会发生钠离子得电子还原为钠金属的电化学反应，反应初期负极集流体表面钠金属不均匀沉积形成枝晶，枝晶尖端由于尖端效应具有较高的负电荷密度，进而影响二次电池的循环性能。
本申请上述实施方式的技术方案中，正极极片的正极活性材料层中含 有钠离子活性材料，且负极极片的负极膜层含有碳材料及电解质中同时包含有钠盐和锂盐，由于电解质的钠盐和锂盐中的锂离子与钠离子均为正一价阳离子，带一个单位正电荷，且锂离子半径更小具有更高的正电荷密度，而负极膜层中上碳材料本身具有自由电子，相对更容易吸附正电荷密度较高的锂离子，故而在二次电池的充电过程中，使得锂离子先于钠离子在枝晶尖端分布，有效地降低了钠离子继续在钠枝晶尖端处的沉积形成有效的电荷屏蔽层，抑制了钠枝晶生长，进而极大地提升了上述二次电池的循环性能。
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，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材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，负极膜层中的碳材料可采用本领域公知的用于电池的碳材料。作为示例，在一些实施例中，负极膜层中的碳材料包括碳纳米管、石墨、石墨烯、碳纤维、中间相炭微球、玻璃碳、软炭、硬炭、中的至少一种。其中，石墨包括人造石墨、天然石墨中的至少一种，具体地，石墨可为膨胀石墨、高取向石墨、三维石墨等。但本申请并不限定于这些材料。上述负极膜层中的碳材料可以仅单独使用一种，也可以将两种以上组合使用。
进一步地优选地，负极膜层中的碳材料为石墨、石墨烯和碳纤维中的至少一种。
在一些具体示例中，上述含有碳材料的负极膜层为碳材料涂层。
在一些实施例中，上述含有碳材料的负极膜层的厚度为0.3μm～3μm，上述含有碳材料的负极膜层的面密度为5g～50g/m 2。该负极膜层的厚度和面密度在所给定范围，可进一步促使锂离子在负极膜层上吸附，进一步有效地抑制了钠枝晶生长。
在一些实施方式中，负极膜层中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，负极膜层中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，例如碳材料、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。
[正极极片]
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活性材料层，所述正极活性材料层包括钠离子活性材料，其中钠离子活性材料作为正极活性材料。
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，正极活性材料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，正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，钠离子活性材料可包括以下材料中的至少一种：钠过渡金属氧化物、聚阴离子型化合物和普鲁士蓝类化合物中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作钠离子电池正极活性材料的传统公知的材料。
作为本申请可选的技术方案，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中的至少一种。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。
作为本申请可选的技术方案，聚阴离子型化合物可以是具有钠离子、过渡金属离子及四面体型(YO 4) n-阴离子单元的一类化合物。过渡金属可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种；Y可以是P、S及Si中的至少一种；n表示(YO 4) n-的价态。
聚阴离子型化合物还可以是具有钠离子、过渡金属离子、四面体型(YO 4) n-阴离子单元及卤素阴离子的一类化合物。过渡金属可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种；Y可以是P、S及Si中的至少一种，n表示(YO 4) n-的价态；卤素可以是F、Cl及Br中的至少一种。
聚阴离子型化合物还可以是具有钠离子、四面体型(YO 4) n-阴离子单元、多面体单元(ZO y) m+及可选的卤素阴离子的一类化合物。Y可以是P、S及Si中的至少一种，n表示(YO 4) n-的价态；Z表示过渡金属，可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种，m表示(ZO y) m+的价态；卤素可以是F、Cl及Br中的至少一种。
聚阴离子型化合物例如是NaFePO 4、Na 3V 2(PO4) 3(磷酸钒钠，简称NVP)、Na 4Fe 3(PO 4) 2(P 2O 7)、NaM’PO4F(M’为V、Fe、Mn及Ni中的一种或几种)及Na 3(VO y) 2(PO 4) 2F 3-2y(0≤y≤1)中的至少一种。
普鲁士蓝类化合物可以是具有钠离子、过渡金属离子及氰根离子(CN -)的一类化合物。过渡金属可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种。普鲁士蓝类化合物例如为Na aMe bMe’ c(CN) 6，其中Me及Me’各自独立地为Ni、Cu、Fe、Mn、Co及Zn中的至少一种，0＜a≤2，0＜b＜1，0＜c＜1。
在一些实施方式中，正极活性材料层中还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极活性材料层中还可选地包括导电剂。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，例如钠离子活性材料、导电剂、粘结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。
[电解质]
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。
在一些实施例中，以电解质的质量为基准，锂盐的质量含量为0.1％～10％。一方面，控制电解质中锂盐在给定范围，可以使锂离子在负极表面形成有效的电荷屏蔽层，从而抑制钠枝晶生长。另一方面，又可避免锂离子浓度过高，导致锂离子在负极集流体表面密度过高，进而增加钠金属沉积的过电位的问题。
可理解，以电解质的质量为基准，锂盐的质量含量可以为0.1％、0.2％、0.5％、0.8％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％。进一步地，以电解质的质量为基准，锂盐的质量含量可以为0.5％～5％、0.5％～2％、0.5％～1％。
同时考虑到负极膜层中的碳材料本身有自由电子，比较容易吸附正电荷密度较高的锂离子，这将会造成电解质中有效的锂离子浓度降低。因而随着该含有碳材料的负极膜层的面密度增加，锂盐的最优浓度也会增加。故而，锂盐会随底该负极膜层的涂布面密度存在如下的最优浓度范围。
在一些实施例中，上述含有碳材料的负极膜层的面密度为x g/m 2，x＝5g～50g/m 2；以电解质的质量为基准，锂盐的质量含量为y％；
x和y满足如下条件：0.84≤y-0.01x≤5.84。
进一步地，上述含有碳材料的负极膜层的厚度为0.3μm～3μm。
在一些实施例中，锂盐包括六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、三氟乙酸锂(CF 3COOLi)、四苯硼酸锂(LiB(C 6H 5) 4)、三氟甲基磺酸锂(LiSO 3CF 3)、双草酸硼酸锂(LiBOB)、二氟草酸硼酸锂(LiDFOB)、双(氟磺酰)亚胺锂(Li[(FSO 2) 2N])及双(三氟甲基磺酰)亚胺锂(Li[(CF 3SO 2) 2N])中的至少一种。
在一些实施例中，电解质中，钠盐的质量含量为3％～25％。
在一些实施例中，钠盐包括高氯酸钠(NaClO 4)、四氟硼酸钠(NaBF 4)、 六氟磷酸钠(NaPF 6)、六氟砷酸钠(NaAsF 6)、三氟乙酸钠(CF 3COONa)、四苯硼酸钠(NaB(C 6H 5) 4)、三氟甲基磺酸钠(NaSO 3CF 3)、双(氟磺酰)亚胺钠(Na[(FSO 2) 2N])和双(三氟甲基磺酰)亚胺钠(Na[(CF 3SO 2) 2N])中的至少一种。
在一些实施方式中，所述电解质采用电解液。所述电解质除了包括钠盐和锂盐等电解质盐，还包括溶剂。
在一些实施方式中，在电解质中溶剂的质量含量为70％～95％。
在一些示例中，电解质中，溶剂的质量含量为70％～95％；钠盐的质量含量为3％～25％；锂盐占所述电解质的质量比为0.1％～10％。
在一些实施方式中，溶剂包括醚类溶剂、酯类溶剂、烷烃类溶剂及砜类溶剂中的至少一种。
在一些示例中，溶剂包括乙二醇二甲醚、二乙二醇二甲醚、三乙二醇二甲醚、四乙二醇二甲醚、1,3-二氧戊环、碳酸乙烯酯、碳酸丙烯酯、碳酸丁烯酯、碳酸亚乙烯酯、氟代碳酸乙烯酯、碳酸甲乙酯、碳酸二甲酯、碳酸二乙酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、γ-丁内酯、1,3-丙烷磺酸内酯、丙酸甲酯、丁酸甲酯、乙酸乙酯、丙酸乙酯、丙酸丙酯、丁酸乙酯及二甲基亚砜中的至少一种。
在一些实施方式中，所述电解质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。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。
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。
在一些实施方式中，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，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。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、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
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1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2，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，二次电池可以组装成电池模块，电池模块所含二次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3是作为一个示例的电池模块4。参照图3，在电池模块4中，多个二次电池5可以是沿电池模块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二次电池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，多个二次电池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4和图5是作为一个示例的电池包1。参照图4和图5，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6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。
以下为具体实施例。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，均为可以通过市购获得的常规产品。
实施例1
(1)电解液配置。
将除水后的乙二醇二甲醚(DME)、六氟磷酸钠(NaPF 6)、六氟磷酸锂(LiPF 6)按照质量比为85：15：2的的比例称取总计10g样品，随后将称取的样品放入20mL的黑盖玻璃瓶内溶解，待其完全溶解后静置10小时待用。以上操作均在手套箱内进行，手套箱的水、氧含量均控制在1ppm以下。
(2)叠片电池制作。
将浓度为1wt％的碳纳米管水溶液(其中含有0.05wt％的CMC-Na)用刮刀分散至负极集流体上，之后经过烘干、冷压、分切，得到具有碳纳米管底涂层的负极极片。
将正极活性材料磷酸钒钠(NVP)、导电剂碳黑Super P、粘结剂聚偏二氟乙烯(PVDF)按照质量比为90:4:6混合，并用N-甲基吡咯烷酮(NMP)分散均匀得到正极浆料；将正极浆料均匀涂覆于正极集流体上，之后经过烘干、冷压、分切，得到正极极片。
将上述所得到的正、负极极片与隔离膜裁剪为合适尺寸，按顺序叠好，使隔离膜处于正、负极片之间起到隔离正负极的作用，然后用大小合适的铝塑膜将正负极、隔膜封装，留下注液口。
(3)注液与封装。
将所得的叠片电池置于干燥箱内真空85℃条件下烘12小时，取出烘干后的电池。待电池温度冷却至室温时，将步骤(1)所配制的电解液注入到电池中，注液量为0.5g，注液完成后将注液口热封。随后给封装好的电芯上上夹具，在夹具两端施加适合的压力，完成叠片电池的组装。
(4)叠片电池化成与测试
随后对组装好的叠片电池进行化成处理，具体化成步骤如下：在25±3℃下，以0.1C(2.4mA)倍率恒电流充电至3.5V，再以0.1C倍率恒电流放电至3.2V，随后进行循环性能测试；具体的循环测试步骤如下：以1C(24mA)倍率恒电流充电至3.5V，随后1C倍率恒电流放电至3.2V，之后重复1C下的恒电流充放电循环操作，得到循环500圈容量保持率。
实施例2～12
除所用电解液各组分比例不相同之外，实施例2～12的其他步骤与实施例1相同。
实施例13～14
除所用电解液各组分比例、底涂厚度及底涂面密度不相同之外，实施例13～14的其他步骤与实施例1相同。
实施例15
除底涂厚度及底涂面密度不相同之外，实施例13～14的其他步骤与实施例1相同。
实施例16～18
除所用底涂的碳材料的种类不相同之外，实施例16～18的其他步骤与实施例1相同。
对比例1～2
除所用电解液各组分比例不相同之外，对比例1～2的其他步骤与实施例1相同。
各实施例和对比例所用的电解液组成(均为质量比)、底涂碳材料、底涂厚度、底涂面密度、正极活性材料以及制得的电池的循环500圈容量保持率，如下表1所示：
表1
Figure PCTCN2022091479-appb-000001
如图7和表1所示，对比例1～2的500圈容量保持率仅仅为84％、82％； 相较于对比例1～2，实施例1～2的容量保持率达到91％左右，说明实施例1～2分别添加2wt％的LiPF 6与LiAsF 6后电池循环性能得到较大提升。
如图8和表1所示，相较于对比例1～2，实施例3～4的容量保持率达到92％左右，说明实施例3～4分别添加2wt％的LiBF 4和LiDFOB后，电池循环性能得到较大提升。
如图9和表1所示，实施例5～6相较于实施例1～2的区别在于，电解液溶剂由实施例1～2中电解液中的溶剂种类进行更换，具体是将乙二醇二甲醚(DME)换成二乙二醇二甲醚(DEGDME)，两种溶剂属于同类物质，在化学性质上相差不大。同样地，相较于对比例1～2，实施例5～6的容量保持率达到91％左右。表明该电解液配方也能够有效地改善了电池循环性能。
如图10和表1所示，实施例7～8相较于实施例3～4的区别在于，电解液溶剂由实施例3～4中电解液中的溶剂种类进行更换，具体是将乙二醇二甲醚(DME)换成二乙二醇二甲醚(DEGDME)，两种溶剂属于同类物质，在化学性质上相差不大。同样地，相较于对比例1～2，实施例7～8的容量保持率达到91％左右。表明该电解液配方也能够有效地改善了电池循环性能。
如图11和表1所示，实施例9～10分别为根据0.84≤y-0.01x≤5.84，通过底涂面密度计算得到的电解液中的锂盐的质量含量范围的最小边界值与边界外的值。可以看到，实施例9循环500圈容量保持率为88.9％，相较于对比例1～2，具有更优的电池循环性能。而实施例10电解液中的锂盐的质量含量低于上述质量含量范围的最小边界值，即为上述质量含量范围边界外的值，可以看到实施例10的容量保持率相比于实施例9有所降低。
如图12和表1所示，实施例11、实施例12分别为根据0.84≤y-0.01x≤5.84，通过底涂面密度计算得到的电解液中的锂盐的质量含量范围的最大边界值与边界外的值。可以看到，实施例11循环500圈容量保持率为87.1％，相较于对比例1～2，具有更优的电池循环性能。而实施例12电解液中的锂盐的质量含量高于上述质量含量范围的最大边界值，即为上述质量含量范围边界外的值，可以看到实施例12的容量保持率仅仅85.4％，相较于实施例11其优化效果不明显。
如图13和表1所示，实施例13～15中，实施例15为根据0.84≤y-0.01x≤5.84，通过底涂面密度计算得到的电解液中的锂盐的质量含量范围内的值。实施例13～14中锂盐的质量含量在计算所得范围之外。实施例15的容量保持率优于实施例13～14。
从表1中的实施例9～13可知，其区别主要在于锂盐的含量不同，优选地，锂盐在电解质中的质量含量为0.5％～1％。
如图14和表1所示，实施例1、实施例16～18中，实施例16～18的容量保持率优于实施例1，且实施例18优于实施例17，更优于实施例16。换言之，碳材料的种类更优选碳纤维、石墨烯或石墨。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围，其均应涵盖在本申请的权利要求和说明书的范围当中。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (12)

  1. 一种二次电池，其特征在于，包括：
    负极极片，包括负极集流体及设于所述负极集流体上的负极膜层，所述负极膜层中含有碳材料；
    正极极片，包括正极集流体及设于所述正极集流体上的正极活性材料层，所述正极活性材料层中含有钠离子活性材料；及
    电解质，设于所述负极极片与所述正极极片之间，所述电解质中包含有钠盐和锂盐。
  2. 如权利要求1所述的二次电池，其特征在于，所述负极膜层的厚度为0.3μm～3μm，所述负极膜层的面密度为5g～50g/m 2。
  3. 如权利要求1至2任一项所述的二次电池，其特征在于，所述负极膜层中的碳材料包括碳纳米管、石墨、石墨烯和碳纤维中的至少一种。
  4. 如权利要求1至3任一项所述的二次电池，其特征在于，以所述电解质的质量为基准，所述锂盐的质量含量为0.1％～10％。
  5. 如权利要求1至4任一项所述的二次电池，其特征在于，所述负极膜层的面密度为x g/m 2，x＝5g～50g/m 2；以所述电解质的质量为基准，所述锂盐的质量含量为y％；
    x和y满足如下条件：0.84≤y-0.01x≤5.84。
  6. 如权利要求1至5任一项所述的二次电池，其特征在于，所述锂盐包括六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、三氟乙酸锂、四苯硼酸锂、三氟甲基磺酸锂、双草酸硼酸锂、二氟草酸硼酸锂、双(氟磺酰)亚胺锂及双(三氟甲基磺酰)亚胺锂中的至少一种。
  7. 如权利要求1至6任一项所述的二次电池，其特征在于，所述电解质中，所述钠盐的质量含量为3％～25％；
    和/或，所述电解质中还包括溶剂，所述电解质中所述溶剂的质量含量为70％～95％。
  8. 如权利要求7所述的二次电池，其特征在于，所述钠盐包括高氯酸钠、四氟硼酸钠、六氟磷酸钠、六氟砷酸钠、三氟乙酸钠、四苯硼酸钠、三氟甲基磺酸钠、双(氟磺酰)亚胺钠和双(三氟甲基磺酰)亚胺钠中的至少一种；
    和/或，所述溶剂包括醚类溶剂、酯类溶剂、烷烃类溶剂及砜类溶剂中的至少一种。
  9. 如权利要求8所述的二次电池，其特征在于，所述溶剂包括乙二醇二甲醚、二乙二醇二甲醚、三乙二醇二甲醚、四乙二醇二甲醚、1,3-二氧戊环、碳酸乙烯酯、碳酸丙烯酯、碳酸丁烯酯、碳酸亚乙烯酯、氟代碳酸乙烯酯、碳酸甲乙酯、碳酸二甲酯、碳酸二乙酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、γ-丁内酯、1,3-丙烷磺酸内酯、丙酸甲酯、丁酸甲酯、乙酸乙酯、丙酸乙酯、丙酸丙酯、丁酸乙酯及二甲基亚砜中的至少一种。
  10. 一种电池模组，其特征在于，包含如权利要求1至9任一项所述的二次电池。
  11. 一种电池包，其特征在于，包含如权利要求10所述的电池模组。
  12. 一种用电装置，其特征在于，所述用电装置包括如权利要求1至9任一项所述的二次电池、如权利要求10所述的电池模组和如权利要求11所述的电池包中的至少一种，所述二次电池用于提供电能。
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CN117691191A (zh) * 2024-01-31 2024-03-12 南京理工大学 一种不易燃且耐高压的磺酸内酯基锂电池及电解液

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CN117334917A (zh) * 2023-12-01 2024-01-02 宁德时代新能源科技股份有限公司 二次电池和用电装置
CN117691191A (zh) * 2024-01-31 2024-03-12 南京理工大学 一种不易燃且耐高压的磺酸内酯基锂电池及电解液
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