WO2023141920A1 - 锂金属电池及电子装置 - Google Patents

锂金属电池及电子装置 Download PDF

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WO2023141920A1
WO2023141920A1 PCT/CN2022/074525 CN2022074525W WO2023141920A1 WO 2023141920 A1 WO2023141920 A1 WO 2023141920A1 CN 2022074525 W CN2022074525 W CN 2022074525W WO 2023141920 A1 WO2023141920 A1 WO 2023141920A1
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lithium
lithium metal
metal battery
solvent
electrolyte
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PCT/CN2022/074525
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English (en)
French (fr)
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李文文
李大光
关文浩
陈茂华
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宁德新能源科技有限公司
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Priority to PCT/CN2022/074525 priority Critical patent/WO2023141920A1/zh
Priority to CN202280006926.4A priority patent/CN116368656A/zh
Publication of WO2023141920A1 publication Critical patent/WO2023141920A1/zh
Priority to US18/622,476 priority patent/US20240258570A1/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
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—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
    • H01M10/0567—Liquid materials characterised by the additives
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/381—Alkaline or alkaline earth metals elements
    • H01M4/382—Lithium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0034—Fluorinated solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • H01M2300/004—Three solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the battery field, in particular to a lithium metal battery and an electronic device.
  • batteries With the popularity of consumer electronics products such as notebook computers, mobile phones, handheld game consoles, tablet computers, mobile power supplies and drones, people have increasingly stringent requirements for batteries. For example, not only the battery is required to be light, but also the battery is required to have high capacity and long working life, as well as the ability to charge and discharge quickly.
  • Lithium metal batteries have occupied a mainstream position in the market due to their outstanding advantages such as high energy density, high safety, low self-discharge, no memory effect, and long working life. At present, how to further improve the cycle performance of lithium metal batteries has become the focus of research and development in the field of lithium metal batteries.
  • the current solution to the cycle of lithium metal batteries is mostly to add film-forming additives to promote the formation of a stable solid electrolyte interface, but the consumption of film-forming additives accelerates the degradation of battery performance at the end of the cycle. In view of this, it is necessary to provide a non-aqueous electrolyte and a lithium metal battery with improved cycle performance.
  • the purpose of the present application is to provide a lithium metal battery and an electronic device to improve the cycle performance of the lithium metal battery.
  • the first aspect of the present application provides a lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, and an electrolyte, the electrolyte includes a lithium salt and a solvent, the molar concentration of the lithium salt is Amol/L, and 2 ⁇ A ⁇ 4, for example A can be 2, 2.5, 3, 3.5, 4 or any range therebetween; the solvent includes the first solvent, based on the total mass of the solvent in the electrolyte, the first solvent
  • the mass percentage content is B%, satisfying 10 ⁇ B ⁇ 50, for example, B can be 10, 15, 20, 25, 30, 35, 40, 45, 50 or any range therebetween; wherein, the A and B satisfy the relationship: 40 ⁇ A ⁇ B ⁇ 100, for example, A ⁇ B can be 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 or any in between scope.
  • the inventors of the present application found that by synergistically controlling the concentration of lithium salt and the mass percentage of the first solvent to satisfy the above relational expression, on the one hand, the structure of the negative electrode solid electrolyte interface (SEI) film can be improved, so that the negative electrode lithium metal
  • SEI solid electrolyte interface
  • the solubility of the lithium salt in the first solvent is Cg/100g, satisfying 0.01 ⁇ C ⁇ 5, for example, C can be 0.01, 0.05, 0.1, 0.2, 0.5, 1 , 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or any range therebetween.
  • the applicant has found through research that when the solubility of the lithium salt in the first solvent is controlled within the above range, the coordination of lithium ions in the electrolyte and the corresponding solvation structure are in the form of polymerized ion pairs, with lower maximum occupancy Molecular orbital (HOMO) and higher lowest unoccupied molecular orbital (LUMO), electrochemical stability is improved, and a stable SEI film can be formed on the negative electrode, thereby improving the cycle performance and safety performance of lithium metal batteries.
  • HOMO maximum occupancy Molecular orbital
  • LUMO lowest unoccupied molecular orbital
  • the total mass of the electrolyte accounts for D% of the mass percentage of the lithium metal battery, satisfying: 2 ⁇ D ⁇ 15, for example, D can be 2, 4, 6, 8, 10, 12, 15 or any range in between.
  • D can be 2, 4, 6, 8, 10, 12, 15 or any range in between.
  • the lithium salt includes lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium bistrifluoromethylsulfonyl imide, lithium bisfluorosulfonyl imide, difluorooxalate boric acid At least one of lithium, lithium tetrafluoroborate, and lithium trifluoromethanesulfonate.
  • the mass percentage of the lithium salt is 15% to 60%, for example, 15%, 30%, 45%, 60% or any range therebetween.
  • the applicant has found through research that when the above lithium salt is selected, it can have higher ionic conductivity, thereby improving the cycle performance of lithium metal batteries.
  • the first solvent includes at least one of the compounds represented by the following general formula:
  • R 1 and R 2 are each independently selected from C 1 to C 10 alkyl, C 2 to C 10 alkenyl, C 1 to C 10 haloalkyl, C 2 to C 10 silyl, C 2 to C 10 haloalkene radical, C 6 to C 26 aryl, C 6 to C 26 haloaryl or C 1 to C 10 alkoxy;
  • R 3 to R 8 are each independently selected from -F, -H, C 1 to C 10 haloalkyl or C 2 to C 10 haloalkenyl;
  • R 9 and R 10 are each independently selected from C 1 to C 10 alkyl, C 2 to C 10 alkenyl, C 1 to C 10 haloalkyl, C 2 to C 10 silyl, C 2 to C 10 haloalkene Base, C 6 to C 26 aryl, C 6 to C 26 haloaryl or C 1 to C 10 haloalkoxy;
  • R 11 and R 12 are each independently selected from C 1 to C 10 alkyl, C 2 to C 10 alkenyl, C 1 to C 10 haloalkyl, C 2 to C 10 silyl, or C 2 to C 10 halo Alkenyl;
  • R 13 and R 14 are each independently selected from C 1 to C 10 alkyl, C 2 to C 10 alkenyl, C 1 to C 10 haloalkyl or C 2 to C 10 haloalkenyl.
  • the cycle performance and safety performance of the lithium metal battery can be further improved.
  • the first solvent includes at least one of the following compounds:
  • the applicant has found through research that when the above-mentioned fluorine-containing solvent is selected as the first solvent, a stable SEI film containing more lithium fluoride (LiF) and high ion conductivity can be formed, thereby enhancing the lithium metal The cycle performance and safety performance of the battery.
  • a stable SEI film containing more lithium fluoride (LiF) and high ion conductivity can be formed, thereby enhancing the lithium metal The cycle performance and safety performance of the battery.
  • the electrolyte solution further includes a second solvent
  • the second solvent includes carbonate compounds, carboxylate compounds, compounds containing sulfur and oxygen double bonds, acid anhydrides, amide compounds, At least one of nitrile compounds, ether compounds, thioether compounds, phosphate compounds, and ionic liquids containing organic cations.
  • the applicant has found through research that by selecting the above-mentioned non-aqueous solvent as the second solvent, the lithium salt in the system can be dissociated to ensure the rapid transmission of lithium ions, increase the kinetics of the lithium metal battery system, and thereby improve the lithium battery. Cycle performance and safety performance of metal batteries.
  • the carbonate compounds include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl propyl carbonate , vinylene carbonate, fluoroethylene carbonate;
  • the carboxylate compounds include methyl formate, ethyl acetate, propyl acetate, ethyl propionate, propyl propionate, ⁇ -butyl At least one of the lactones;
  • the compounds containing sulfur and oxygen double bonds include vinyl sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, diethyl sulfate, dimethyl sulfone, At least one of diethyl sulfone, dimethyl sulfoxide, diethyl sulfoxide, sulfolane, and N,N-dimethyltrifluoromethanesulfonamide;
  • the mass percentage of the second solvent is 10% to 60%, such as 10%, 15%, 20%, 25% %, 30%, 35%, 40%, 45%, 50%, 55%, 60%, or any range therebetween.
  • the applicant has found through research that when the mass percentage of the second solvent was too high (greater than 60%), the concentration of lithium ions in the electrolyte was diluted and the circulation decayed; when the mass percentage of the second solvent was too low ( less than 10%), the dissociation degree of the electrolyte to the lithium salt is insufficient, and the lithium salt is easy to deposit and separate out in a low temperature environment.
  • the electrolyte solution also includes a third component, and the third component includes ethylene carbonate, methylene methanedisulfonate, 4-trifluoromethylethylene carbonate ester, 1,3,2-dioxazolethiophene-2,2-dioxide, succinic anhydride, propenyl-1,3-sultone, bis(trimethylsilyl)sulfate, N- Methyl, butylpyrrolidine bistrifluoromethanesulfonimide salt, N-methyl, propylpiperidine bistrifluoromethanesulfonimide salt, 1,2-bis(cyanoethoxy)ethane, At least one of adiponitrile, 1,3,5-pentanetricarbonitrile, fumaronitrile or 1,2,3-tris(2-cyanoethoxy)propane.
  • the third component includes ethylene carbonate, methylene methanedisulfonate, 4-trifluoromethylethylene carbonate ester, 1,3,
  • the above-mentioned compound is selected as the third component, and the above-mentioned compound can decompose and form a film on the surface of the negative electrode sheet to protect the stability of the negative electrode during cycling, thereby improving the cycle performance of the lithium metal battery.
  • the mass percentage of the third component is 0.01% to 10%, such as 0.01%, 0.05%, 0.1%, 0.5% , 1%, 1.5%, 2.5%, 3.5%, 4.5%, 5.5%, 6.5%, 7.5%, 8.5%, 9.5%, 10%, or any range therebetween.
  • the applicant has found through research that when the mass percentage of the third component is too high (greater than 10%), the coordination structure of lithium ions will be destroyed, the film forming resistance will increase, and the cycle performance will deteriorate; when the third component If the mass percentage is too low (less than 0.01%), the cycle performance and safety performance of the lithium metal battery will not be significantly improved.
  • the porosity of the positive electrode sheet is E%, which satisfies 5 ⁇ E ⁇ 35, for example, E can be 5, 10, 15, 20, 25, 30, 35 or any in between range; and 0.5 ⁇ E/D ⁇ 15, for example, E/D can be 0.5, 1, 1.5, 3.5, 5.5, 7.5, 9.5, 12.5, 15 or any range therebetween.
  • the applicant has found through research that when the porosity of the positive pole piece is too high (E is greater than 35), the content of the electrolyte required to infiltrate the pole piece is higher, and the safety performance is reduced; when the porosity of the positive pole piece is too low (E is less than 0.5), the ion channels in the positive electrode sheet are insufficient, and the polarization resistance of the lithium metal battery is too large, resulting in deterioration of kinetic performance and cycle performance.
  • the lithium metal battery and electronic device provided by the present application realize less liquid injection in the lithium metal battery by regulating the composition of the fluorine-containing solvent in the electrolyte and the composition and structure of the SEI film on the negative electrode side, so that the lithium metal negative electrode
  • the deposition/stripping process is more uniform, which greatly improves the cycle performance of lithium metal batteries; on the other hand, the ionic conductivity of the SEI film is high, and it does not require very much during the cycle without affecting the charge and discharge performance of the battery. Electrolyte consumption, thereby reducing the amount of liquid injection to improve safety.
  • Fig. 1 is the surface scanning electron microscope picture of negative pole sheet in embodiment 1;
  • Fig. 2 is the surface scanning electron microscope picture of negative pole sheet in embodiment 2;
  • Fig. 3 is the enlarged scanning electron microscope picture of the section of the negative pole piece in embodiment 1;
  • Fig. 4 is the cross-sectional scanning electron microscope picture of negative pole piece in embodiment 1;
  • FIG. 5 is a charge-discharge curve diagram of Example 1 at 25° C. with different cycle numbers.
  • the positive electrode sheet in this application is not particularly limited, as long as the purpose of this application can be achieved.
  • the positive pole piece generally includes a positive current collector and a positive active material.
  • the above-mentioned positive electrode current collector is not particularly limited, and may be any positive electrode current collector known in the art, such as copper foil, aluminum foil, aluminum alloy foil, composite current collector, and the like.
  • the above-mentioned positive electrode active material is not particularly limited, and may be any positive electrode active material in the prior art, for example, may include lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium iron phosphate, lithium cobaltate, lithium manganate or ferromanganese phosphate at least one of lithium.
  • the thicknesses of the positive electrode current collector and the positive electrode active material are not particularly limited, as long as the purpose of the present application can be achieved.
  • the thickness of the positive electrode current collector is 8 ⁇ m to 12 ⁇ m
  • the thickness of the positive electrode active material is 30 ⁇ m to 120 ⁇ m.
  • a conductive agent may also be included in the positive electrode material layer, and the present application has no special limitation on the conductive agent, as long as the purpose of the application can be realized, for example, it may include but not limited to conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fiber, flake graphite, Ketjen black, graphene, metal material or conductive polymer.
  • the aforementioned carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
  • the aforementioned carbon fibers may include, but are not limited to, vapor grown carbon fibers (VGCF) and/or carbon nanofibers.
  • the above metal material may include but not limited to metal powder and/or metal fiber, specifically, the metal may include but not limited to at least one of copper, nickel, aluminum or silver.
  • the aforementioned conductive polymer may include but not limited to at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene or polypyrrole.
  • the positive electrode active material layer may also include a binder.
  • the present application has no special restrictions on the binder, as long as the purpose of the application can be achieved, for example, it may include but not limited to polyvinyl alcohol, hydroxypropyl fiber Polyvinyl chloride, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1-bis Vinyl fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (ester) styrene-butadiene rubber, epoxy resin, nylon, etc.
  • the positive electrode may further include a conductive layer located between the positive electrode current collector and the positive electrode material layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the field, for example, may include but not limited to the above-mentioned conductive agent and the above-mentioned binder.
  • the negative electrode sheet in this application is not particularly limited, as long as the purpose of this application can be achieved.
  • the negative electrode sheet can include a negative electrode active material layer, and the negative electrode active material layer can include metal lithium or its compound or lithium alloy layer and lithium copper complex, etc., and can further include a negative electrode current collector, and the negative electrode current collector is used for In order to support the negative electrode active material layer and conduct current, the shape may be a foil or a mesh.
  • the material of the negative electrode collector can be selected from copper, nickel or stainless steel.
  • the negative electrode material layer may also include a conductive agent.
  • the present application has no special limitation on the conductive agent, as long as the purpose of the present application can be achieved, for example, it may include but not limited to at least one of the above-mentioned conductive agents.
  • the negative electrode material layer may also include a binder, and the present application has no special restrictions on the binder, as long as the purpose of the application can be achieved, for example, it may include but not limited to at least one of the above-mentioned binders .
  • the negative electrode may further include a conductive layer located between the negative electrode current collector and the negative electrode material layer.
  • the present application has no particular limitation on the composition of the conductive layer, which may be a commonly used conductive layer in the art, and the conductive layer may include but not limited to the above-mentioned conductive agent and the above-mentioned binder.
  • the separator in the present application is not particularly limited, as long as the purpose of the application can be achieved, the separator substrate can be selected from polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), At least one of polyimide (PI) or aramid fiber.
  • polyethylene includes at least one component selected from high-density polyethylene, low-density polyethylene, and ultra-high molecular weight polyethylene.
  • polyethylene and polypropylene have an excellent effect on preventing short circuits and can improve the stability of electrochemical devices through the shutdown effect.
  • the separator of the present application may have a porous structure, and the pore size is not particularly limited as long as the purpose of the present application can be achieved, for example, the pore size may be 0.01 ⁇ m to 1 ⁇ m.
  • the thickness of the isolation film is not particularly limited, as long as the purpose of the present application can be achieved, for example, the thickness may be 5 ⁇ m to 500 ⁇ m.
  • the electrolyte solution can also include other non-aqueous solvents, and the present application has no special restrictions on other non-aqueous solvents, as long as the purpose of the application can be realized, for example, it can include but not limited to ethylene propyl carbonate (EPC) , butylene carbonate (BC), tert-butyl acetate, decanolactone, valerolactone, mevalonolactone or caprolactone, tetraglyme, diglyme, 1,2- One or more of diethoxyethane and ethoxymethoxyethane.
  • EPC ethylene propyl carbonate
  • BC butylene carbonate
  • tert-butyl acetate decanolactone
  • valerolactone valerolactone
  • mevalonolactone or caprolactone mevalonolactone or caprolactone
  • tetraglyme diglyme
  • the mass percentage of the other non-aqueous solvents is 1% to 50%, such as 1%, 5%, 10%, 15%, 20%, 30%, 35% , 40%, 45%, 50%, or any range in between.
  • the electronic device in this application is not particularly limited, and it may be any electronic device known in the prior art.
  • electronic devices may include, but are not limited to, notebook computers, pen-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, headsets, VCRs, 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 household storage batteries and lithium-ion capacitors, etc.
  • a lithium metal battery can be manufactured through the following process: the positive electrode and the negative electrode are overlapped through a separator, and they are wound, folded, etc. as required and put into the case, and the electrolyte is injected into the case and sealed.
  • anti-overcurrent elements, guide plates, etc. can also be placed in the casing according to needs, so as to prevent the internal pressure of the lithium metal battery from rising and overcharging and discharging.
  • Capacity retention rate residual discharge capacity/initial discharge capacity ⁇ 100%.
  • the lithium metal battery at a constant current of 0.5C to 4.2V at 20 ⁇ 5°C, charge it at a constant voltage of 4.2V to 0.05C, set the furnace temperature to 25°C, and start heating at a rate of 5 ⁇ 2°C/min after standing for 30 minutes , raise the temperature to the specified temperature ⁇ 2°C, keep it for 60 minutes, and monitor the voltage, lithium metal battery surface temperature and furnace temperature changes during the process, as well as whether there is leakage, fire or explosion.
  • the mass percentage of the electrolyte the mass of the electrolyte/the mass of the lithium metal battery ⁇ 100%.
  • the porosity of the pole piece is tested by the gas displacement method: the pore volume of the sample accounts for the percentage E% of the total volume of the sample.
  • E% [(VV 0 )/V] ⁇ 100%.
  • the lithium metal battery was disassembled to obtain the negative pole piece, which was cut into small pieces (10mm ⁇ 10mm) and placed in a scanning electron microscope (SEM) (ZEISS SEM (Sigma-02-33)), the surface topography of the negative electrode sheet was observed at different magnifications.
  • SEM scanning electron microscope
  • the solvent is mixed according to the ratio shown in Table 1, and the balance is ethylene carbonate, and lithium bisfluorosulfonyl imide is added according to the lithium salt concentration in Table 1 to form an electrolyte.
  • the positive electrode active material NCM811 LiNi 0.8 Mn 0.1 Co 0.1 O 2
  • the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) were mixed according to a weight ratio of 96:2:2, and N-methylpyrrolidone ( NMP) was used as a solvent, prepared into a slurry with a solid content of 75%, and stirred under the action of a vacuum mixer until the system became a uniform positive electrode slurry.
  • the positive electrode slurry was uniformly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 10 ⁇ m, and dried at 90° C.
  • the positive electrode sheet with a positive electrode active material layer coated on one side with a thickness of 110 ⁇ m.
  • the single-side coating of the positive electrode sheet is completed.
  • the above steps are repeated on the other surface of the positive electrode sheet to obtain a positive electrode sheet coated with positive active materials on both sides.
  • the positive electrode sheet is cold-pressed and cut into required specifications for use. After testing, the porosity of the positive electrode sheet is 17.9%.
  • the metal lithium foil is placed on one surface of the negative electrode current collector copper foil with a thickness of 8 ⁇ m, and the pressure roll is carried out with an appropriate force, so that the metal lithium and the current collector are bonded to obtain a single-sided negative electrode sheet. Afterwards, the above steps are repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet loaded with negative active materials on both sides.
  • Polyethylene (PE) porous polymer film is used as the isolation membrane.
  • Example 1 Except adjusting the kind and content of each solvent according to Table 1, all the other are the same as Example 1.
  • Example 1 Except for adjusting relevant preparation parameters according to Table 1, the rest are the same as in Example 1.
  • Example 21 to Example 28 it can be seen that the cycle performance and safety performance of the lithium metal battery change with the change of the second solvent and the third component.
  • Example 22 to Example 23 it can be seen that the lithium metal battery whose type and mass percentage content of the second solvent is selected within the scope of the application can have better cycle performance and safety performance; the second solvent and the third The type of components will also affect the cycle performance and safety performance of the lithium metal battery.
  • the second solvent and the third component are selected within the scope of the lithium metal battery of the application. Cyclic performance and safety performance have been significantly improved.
  • Example 29 2 25 0.1 5 20 4 86.7 131
  • Example 30 3 30 0.1 5 20 4 85.5 131
  • Example 31 2 25 0.01 5 5 1 88.2 135
  • Example 32 2 25 0.5 5 10 2 87.9 127
  • Example 33 2 25 1 5 30 6 86.8 127
  • Example 34 2 25 3 5 35 7 86.1 129
  • Example 35 3 30 0.1 8 20 2.5 89.3 136
  • Example 36 3 3 30 0.1 10 10 1 87.8 134
  • Example 37 3 30 0.1 10 15 1.5 87.9 133
  • Example 38 3 3 30 0.1 15 9 0.6 86.4 128
  • the cycle performance and safety performance of the lithium metal battery change with the change of the porosity of the positive pole piece, the ratio of the porosity and the mass percentage of the electrolyte.
  • the ratio of the porosity of the positive pole piece to the mass percentage of the electrolyte usually also affects the cycle performance and safety performance of the lithium metal battery.
  • the mass percentage of the electrolyte is In the case of a certain content, when the content of the electrolyte in the lithium metal battery is higher, the cycle performance of the lithium metal battery is significantly improved.

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Abstract

一种锂金属电池及电子装置，其包括正极极片、负极极片以及电解液，电解液包括锂盐和溶剂，锂盐的摩尔浓度为Amol/L，且2≤A≤4；溶剂包含第一溶剂，基于电解液中溶剂的总质量，第一溶剂的质量百分含量为B％，满足10≤B≤50；其中，锂金属电池满足关系式：40≤A×B≤100。本申请提供的锂金属电池及电子装置，通过调控电解液中含氟溶剂的组分以及负极侧SEI膜的组分和结构，提高了锂金属电池的循环性能和安全性能。

Description

锂金属电池及电子装置 技术领域
本申请涉及电池领域，尤其涉及一种锂金属电池及电子装置。
背景技术
随着消费电子类的产品如笔记本电脑、手机、掌上游戏机、平板电脑、移动电源和无人机等的普及，人们对其中的电池要求越来越严格。例如，不仅要求电池轻便，而且还要求电池拥有高容量和长的工作寿命以及快速充放电的能力。
锂金属电池凭借其具有能量密度高、安全性高、自放电低、无记忆效应、工作寿命长等突出优点已经在市场上占据主流地位。目前，如何进一步提升锂金属电池的循环性能已成锂金属电池领域的研发重点。
当前解决锂金属电池循环的方法大多是加入成膜添加剂，促进生成稳定的固体电解质界面，但成膜添加剂的消耗使得在循环后期电池性能衰减加速。有鉴于此，确有必要提供一种循环性能改进的非水电解液和锂金属电池。
发明内容
本申请的目的在于提供一种锂金属电池及电子装置，改善锂金属电池的循环性能。
本申请的第一方面提供了一种锂金属电池，其包括正极极片、负极极片以及电解液，所述电解液包括锂盐和溶剂，所述锂盐的摩尔浓度为Amol/L，且2≤A≤4，例如A可以为2、2.5、3、3.5、4或为其间的任意范围；所述溶剂包含第一溶剂，基于所述电解液中溶剂的总质量，所述第一溶剂的质量百分含量为B％，满足10≤B≤50，例如，B可以为10、15、20、25、30、35、40、45、50或为其间的任意范围；其中，所述A和B满足关系式：40≤A×B≤100，例如A×B可以为40、45、50、55、60、65、70、75、80、85、90、95、100或为其间的任意范围。
经过深入研究，本申请发明人发现，通过协同控制锂盐浓度和第一溶剂的质量百分含量满足上述关系式，一方面可以改善负极固体电解质界面(SEI)膜的结构，使负极锂金属的沉积和剥离过程更加均匀，改善了锂金属电池的循环性能；另一方面提升了SEI膜的离子电导率，减少循环过程中电解液的消耗，从而可以降低电解液的含量提升锂金属电池的安全性能。
本申请的一种实施方案中，所述锂盐在所述第一溶剂中的溶解度为Cg/100g，满足0.01≤C≤5，例如，C可以为0.01、0.05、0.1、0.2、0.5、1、1.5、2、2.5、3、3.5、4、4.5、 5或为其间的任意范围。本申请人经研究发现，当控制锂盐在第一溶剂中的溶解度在上述范围内时，电解液中锂离子配位和相应的溶剂化结构表现为聚合离子对形式，有更低的最高占据分子轨道(HOMO)和更高的最低未占分子轨道(LUMO)，电化学稳定性提高，同时可以在负极生成稳定的SEI膜，从而提高锂金属电池的循环性能和安全性能。
本申请的一种实施方案中，所述电解液的总质量占锂金属电池的质量百分含量为D％，满足：2≤D≤15，例如，D可以为2、4、6、8、10、12、15或为其间的任意范围。本申请人经研究发现，当电解液的质量百分含量过低时(D小于2)，电解液无法在正极孔隙内部润湿，循环过程中没有足够的锂离子通道，导致锂金属电池衰减较快；当电解液含量过高时(D大于15)，电解液分布不均匀，而且电解液与负极之间反应产生大量副产物，循环性能和安全性能均恶化；当控制电解液的质量百分含量在上述范围内时，电解液将孔隙充分润湿，能够提供足够的电子通路，且无较多的副产物，从而提高锂金属电池的循环性能和安全性能。
本申请的一种实施方案中，所述锂盐包括高氯酸锂、六氟砷酸锂、六氟磷酸锂、双三氟甲基磺酰亚胺锂、双氟磺酰亚胺锂、二氟草酸硼酸锂、四氟硼酸锂、三氟甲基磺酸锂中的至少一种。本申请中，基于电解液的总质量，所述锂盐的质量百分含量为15％至60％，例如，可以为15％、30％、45％、60％或为其间的任意范围。不限于任何理论，本申请人经研究发现，当选择上述锂盐时，可以有较高的离子导电率，从而改善锂金属电池的循环性能。
本申请的一种实施方案中，所述第一溶剂包括下列通式所示化合物中的至少一种：
Figure PCTCN2022074525-appb-000001
其中，
R 1、R 2各自独立地选自C 1至C 10烷基、C 2至C 10烯基、C 1至C 10卤代烷基、C 2至C 10硅烷基、C 2至C 10卤代烯基、C 6至C 26芳基、C 6至C 26卤代芳基或C 1至C 10烷氧基；
R 3至R 8各自独立地选自-F、-H、C 1至C 10卤代烷基或C 2至C 10卤代烯基；
R 9、R 10各自独立地选自C 1至C 10烷基、C 2至C 10烯基、C 1至C 10卤代烷基、C 2至C 10硅烷基、C 2至C 10卤代烯基、C 6至C 26芳基、C 6至C 26卤代芳基或C 1至C 10卤代烷氧基；
R 11、R 12各自独立地选自C 1至C 10烷基、C 2至C 10烯基、C 1至C 10卤代烷基、C 2至C 10硅烷基、或C 2至C 10卤代烯基；
R 13、R 14各自独立地选自C 1至C 10烷基、C 2至C 10烯基、C 1至C 10卤代烷基或C 2至C 10卤代烯基。
不限于任何理论，当选择上述范围内的溶剂为第一溶剂时，能够进一步提升锂金属电池的循环性能和安全性能。
本申请的一种实施方案中，所述第一溶剂包括下式化合物中的至少一种：
Figure PCTCN2022074525-appb-000002
不限于任何理论，本申请人经研究发现，当选择上述含氟溶剂作为第一溶剂时，能够生成含有较多氟化锂(LiF)的稳定、高离子传导率的SEI膜，从而提升锂金属电池的循环性能和安全性能。
本申请的一种实施方案中，所述电解液还包括第二溶剂，所述第二溶剂包括碳酸酯类化合物、羧酸酯类化合物、含硫氧双键的化合物、酸酐、酰胺类化合物、腈类化合物、醚类化合物、硫醚类化合物、磷酸酯类化合物、含有机阳离子的离子液体中的至少一种。不限于任何理论，本申请人经研究发现，通过选择上述非水溶剂作为第二溶剂可以解离体系中的锂盐，保证锂离子的快速传输，增加锂金属电池体系的动力学，从而提高锂金属电池的循环性能和安全性能。
本申请的一种实施方案中，所述碳酸酯类化合物包括碳酸亚乙酯、碳酸亚丙酯、碳酸二甲酯、碳酸二乙酯、碳酸二丙酯、碳酸甲乙酯、碳酸甲丙酯、碳酸亚乙烯酯、氟代碳酸乙烯酯中的至少一种；所述羧酸酯类化合物包括甲酸甲酯、乙酸乙酯、乙酸丙酯、丙酸乙酯、丙酸丙酯、γ-丁内酯中的至少一种；所述含硫氧双键的化合物包括亚硫酸乙烯酯、亚硫酸丙烯酯、亚硫酸二甲酯、亚硫酸二乙酯、硫酸二乙酯、二甲基砜、二乙基砜、二甲基亚砜、二乙基亚砜、环丁砜、N,N-二甲基三氟甲磺酰胺中的至少一种；所述酸酐包括乙酸 酐和/或丙酸酐；所述酰胺类化合物包括N-甲基吡咯烷酮、N-甲基甲酰胺、N-甲基乙酰胺、N,N-二甲基甲酰胺中的至少一种；所述腈类化合物包括乙腈、丙腈、丁腈中的至少一种；所述醚类化合物包括四氢呋喃、乙二醇二甲醚、乙二醇二乙醚、乙二醇二丙醚、乙二醇二丁醚、二乙二醇二甲醚、三乙二醇二甲醚、四乙二醇二甲醚中的至少一种；所述硫醚类化合物包括乙硫醚和/或甲硫醚；所述磷酸酯类化合物包括磷酸三甲酯、磷酸三乙酯、2-乙氧基-2-氧-1,3,2-二氧磷杂环戊烷、2-三氟乙氧基-2-氧-1,3,2-二氧磷杂环戊烷中的至少一种；所述含有机阳离子的离子液体包括含1-丁基-3-甲基咪唑基阳离子、1-甲基-1-乙基吡咯烷基阳离子、N-丁基-N-甲基哌啶阳离子的离子液体中的至少一种，例如所述含有机阳离子的离子液体可以为1-丁基-3-甲基咪唑双氟磺酰亚胺盐。不限于任何理论，本申请人经研究发现，通过选择上述非水溶剂作为第二溶剂可以解离体系中的锂盐，可以进一步提高锂金属电池的循环性能和安全性能。
本申请的一种实施方案中，基于所述电解液中溶剂的总质量，所述第二溶剂的质量百分含量为10％至60％，例如可以为10％、15％、20％、25％、30％、35％、40％、45％、50％、55％、60％或为其间的任意范围。本申请人经研究发现，当第二溶剂的质量百分含量过高时(大于60％)，电解液中锂离子浓度被稀释，循环衰减；当第二溶剂的质量百分含量过低时(小于10％)，电解液对锂盐的解离度不足，锂盐在低温环境中容易沉积析出。
本申请的一种实施方案中，所述电解液还包含第三组分，所述第三组分包括碳酸乙烯亚乙酯、甲烷二磺酸亚甲酯、4-三氟代甲基碳酸乙烯酯、1,3,2-二噁唑噻吩-2,2-二氧化物、丁二酸酐、丙烯基-1,3-磺酸内酯、双(三甲基硅基)硫酸酯、N-甲基,丁基吡咯烷双三氟甲磺酰亚胺盐、N-甲基,丙基哌啶双三氟甲磺酰亚胺盐、1,2-双(氰乙氧基)乙烷、己二腈、1,3,5-戊三甲腈、反丁烯二腈或1,2,3-三(2-氰乙氧基)丙烷中的至少一种。本申请人经研究发现，选择上述化合物作为第三组分，上述化合物可以在负极极片表面分解成膜，保护负极在循环过程中的稳定性，从而改善锂金属电池的循环性能。
本申请的一种实施方案中，基于所述电解液的总质量，所述第三组分的质量百分含量为0.01％至10％，例如可以为0.01％、0.05％、0.1％、0.5％、1％、1.5％、2.5％、3.5％、4.5％、5.5％、6.5％、7.5％、8.5％、9.5％、10％或为其间的任意范围。本申请人经研究发现，当第三组分的质量百分含量过高时(大于10％)，会破坏锂离子的配位结构，成膜阻抗增加，循环性能恶化；当第三组分的质量百分含量过低(小于0.01％)，对锂金属电池的循环性能和安全性能改善不明显。
本申请的一种实施方案中，所述正极极片的孔隙率为E％，满足5≤E≤35，例如E可以为5、10、15、20、25、30、35或为其间的任何范围；并且0.5≤E/D≤15，例如E/D可以为0.5、1、1.5、3.5、5.5、7.5、9.5、12.5、15或为其间的任何范围。本申请人经研究发现，当正极极片孔隙率过高时(E大于35)，浸润极片所需电解液的含量较高，安全性能降低；当正极极片孔隙率过低时(E小于0.5)，正极极片中的离子通道不足，锂金属电池的极化阻抗过大，导致动力学性能和循环性能恶化。
本申请的有益效果：
本申请提供的锂金属电池及电子装置，通过调控电解液中含氟溶剂的组分以及负极侧SEI膜的组分和结构，实现锂金属电池中更少的注液量，使得锂金属负极的沉积/剥离过程更加均匀，大大改善了锂金属电池的循环性能；另一方面，SEI膜的离子电导率较高，在不影响电池的充放电性能情况下，在循环过程中不需要非常多的电解液消耗，进而实现降低注液量的方式来提升安全性。
附图说明
为了更清楚地说明本申请实施例和现有技术的技术方案，下面对实施例和现有技术中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，本领域普通技术人员来讲还可以根据这些附图获得其他的附图。
图1为实施例1中负极极片的表面扫描电镜图片；
图2为实施例2中负极极片的表面扫描电镜图片；
图3为实施例1中负极极片的剖面放大扫描电镜图片；
图4为实施例1中负极极片的剖面扫描电镜图片；
图5为实施例1在25℃下不同循环圈数的充放电曲线图。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参考附图列举实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。本领域普通技术人员基于本申请中的实施例所获得的所有其他实施例，都属于本申请保护的范围。
本申请中的正极极片没有特别限制，只要能够实现本申请目的即可。所述正极极片通常包含正极集流体和正极活性材料。上述正极集流体没有特别限制，可以为本领域公知的任何正极集流体，例如铜箔、铝箔、铝合金箔以及复合集电体等。上述正极活性材料没有 特别限制，可以为现有技术的任何正极活性材料，例如，可以包括镍钴锰酸锂、镍钴铝酸锂、磷酸铁锂、钴酸锂、锰酸锂或磷酸锰铁锂中的至少一种。
在本申请中，正极集流体和正极活性材料的厚度没有特别限制，只要能够实现本申请目的即可。例如，正极集流体的厚度为8μm至12μm，正极活性材料的厚度为30μm至120μm。
在本申请中，正极材料层中还可以包括导电剂，本申请对导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于导电炭黑(Super P)、碳纳米管(CNTs)、碳纤维、鳞片石墨、科琴黑、石墨烯、金属材料或导电聚合物中的至少一种。上述碳纳米管可以包括但不限于单壁碳纳米管和/或多壁碳纳米管。上述碳纤维可以包括但不限于气相生长碳纤维(VGCF)和/或纳米碳纤维。上述金属材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。上述导电聚合物可以包括但不限于聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。
在本申请中，正极活性材料层中还可以包括粘合剂，本申请对粘合剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚乙烯醇、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂、尼龙等。
任选地，正极还可以包括导电层，导电层位于正极集流体和正极材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，例如可以包括但不限于上述导电剂和上述粘结剂。
本申请中的负极极片没有特别限制，只要能够实现本申请目的即可。所述负极极片可包括负极活性材料层，所述负极活性材料层可以包括金属锂或其化合物或锂合金层以及锂铜复合物等，并可进一步包括负极集流体，所述负极集流体用于担载所述负极活性材料层并传导电流，形状可以为箔片或网状。该负极集流体的材料可以选自铜、镍或不锈钢。
在本申请中，负极材料层中还可以包括导电剂，本申请对导电剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于上述导电剂中的至少一种。
在本申请中，负极材料层中还可以包括粘结剂，本申请对粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于上述粘结剂中的至少一种。
任选地，负极还可以包括导电层，导电层位于负极集流体和负极材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层，导电层可以包括但不限于上 述导电剂和上述粘结剂。
本申请中的隔膜没有特别限制，只要能够实现本申请目的即可，隔离膜基材可以选自聚乙烯(PE)、聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚酰亚胺(PI)或芳纶中的至少一种。举例来说，聚乙烯包括选自高密度聚乙烯、低密度聚乙烯和超高分子量聚乙烯中的至少一种组分。尤其是聚乙烯和聚丙烯，它们对防止短路具有优良的作用，并可以通过关断效应改善电化学装置的稳定性。本申请的隔离膜可以具有多孔结构，孔径的尺寸没有特别限制，只要能实现本申请的目的即可，例如，孔径的尺寸可以为0.01μm至1μm。在本申请中，隔离膜的厚度没有特别限制，只要能实现本申请的目的即可，例如厚度可以为5μm至500μm。
在本申请中，电解液还可以包括其他非水溶剂，本申请对其他非水溶剂没有特别限制，只要能实现本申请的目的即可，例如，可以包括但不限于碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、乙酸叔丁酯、癸内酯、戊内酯、甲瓦龙酸内酯或己内酯、四甘醇二甲醚、二甘醇二甲醚、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷中的一种或者多种。基于所述电解液的总质量，上述其他非水溶剂的的质量百分含量为1％至50％，例如可以为1％、5％、10％、15％、20％、30％、35％、40％、45％、50％或其间的任何范围。
本申请中的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括，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、家庭用大型蓄电池和锂离子电容器等。
锂金属电池的制备过程为本领域技术人员所熟知的，本申请没有特别的限制。例如锂金属电池可以通过以下过程制造：将正极和负极经由隔离膜重叠，并根据需要将其卷绕、折叠等操作后放入壳体内，将电解液注入壳体并封口。此外，也可以根据需要将防过电流元件、导板等置于壳体中，从而防止锂金属电池内部的压力上升、过充放电。
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
具体测试方法和设备
循环性能测试方法：
将锂金属电池放至25℃恒温箱中，以恒定电流0.5C充电至4.5V下，恒压充电至0.05C，再以1.0C恒流放电至3.0V，此为一个充放电循环过程，按上述方式进行100次循环充放电测试，监控容量保持率。
容量保持率＝剩余放电容量/初始放电容量×100％。
热箱测试方法：
将锂金属电池在20±5℃下0.5C恒流充电至4.2V，4.2V下恒压充电至0.05C，设置炉温为25℃，静置30min后开始以5±2℃/min升温速率，升温至指定温度±2℃，保持60min，监控过程中电压、锂金属电池表面温度及炉温的变化以及是否漏液、起火、爆炸。
电解液质量测试：
将锂金属电池拆开，放入样品盒中，倒入碳酸二甲酯(DMC)使电池极片完全浸泡在DMC溶液中，浸泡8h后，换用新的DMC浸泡过夜(14h)。将浸泡后的锂金属电池取出放入烧杯中，放入真空干燥箱中烘烤过夜(14h)。根据锂金属电池浸泡前及烘干后的质量差，算出锂金属电池中的电解液的质量百分含量：
电解液质量百分含量＝电解液质量/锂金属电池质量×100％。
孔隙率的测试方法：
采用气体置换法测试极片孔隙率：样品的孔体积占样品总体积的百分比E％。
将待测的极片冲切成固定大小(直径d＝10mm)且形状规则的圆形小片，称取一定质量的样品小片，置于真密度测试仪(AccuPyc II 1340)中，在密闭测试系统，通入惰性气体，测得样品的真实体积V 0，根据样品小片的面积和厚度计算表观体积V。孔隙率计算如下：
E％＝[(V-V 0)/V]×100％。
沉积形貌测试：
将锂金属电池以0.2C的电流循环5圈后，拆解该锂金属电池得到负极极片，将负极极片裁切成小片(10mm×10mm)，置于扫描电子显微镜(SEM)(ZEISS SEM(Sigma-02-33))中，以不同的放大倍率观察负极极片的表面形貌。
实施例1
(1)电解液的制备
在含水量<10ppm的氩气气氛手套箱中，将溶剂按照表1所示比例混合，余量为碳酸 亚乙酯，按表1的锂盐浓度加入双氟磺酰亚胺锂形成电解液。
(2)正极极片的制备
将正极活性材料NCM811(LiNi 0.8Mn 0.1Co 0.1O 2)、导电剂乙炔黑、粘结剂聚偏二氟乙烯(PVDF)按照重量比96:2:2进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为75％的浆料，并在真空搅拌机作用下搅拌至体系成均匀的正极浆料。将正极浆料均匀涂覆在厚度为10μm的正极集流体铝箔的一个表面上，90℃条件下烘干，得到正极活性材料层厚度为110μm的单面涂布正极活性材料的正极极片。以上步骤完成后，即完成正极极片的单面涂布。之后，在该正极极片的另一个表面上重复以上步骤，即得到双面涂布正极活性材料的正极极片。涂布完成后，将正极极片冷压后裁切成所需的规格待用，经测试，正极极片的孔隙率为17.9％。
(3)负极极片的制备
将金属锂箔片设置在厚度为8μm的负极集流体铜箔的一个表面上，以合适的力进行压辊，使金属锂和集流体贴合，得到单面的负极极片。之后，在该负极极片的另一个表面上重复以上步骤，即得到双面负载负极活性材料的负极极片。
(4)隔离膜
以聚乙烯(PE)多孔聚合物薄膜作为隔离膜。
(5)锂金属电池的制备
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片之间起到隔离的作用，然后卷绕，尾部收尾贴胶，置于冲好的铝箔袋中，将铝箔袋边缘封装，然后放置在85℃真空烘箱中干燥12h，将干电芯中的水分去除，最后将上述制备好的电解液注入到真空干燥后的电池中，经过真空封装、静置、化成、成形等工序，即完成锂金属电池的制备。
实施例2至实施例20
除了按照表1调整各溶剂的种类和含量以外，其余与实施例1相同。
对比例1至对比例3
除了按照表1调整相关制备参数以外，其余与实施例1相同。
表1
Figure PCTCN2022074525-appb-000003
Figure PCTCN2022074525-appb-000004
Figure PCTCN2022074525-appb-000005
从表1以及图1至图5中可以看出，实施例1至实施例20、对比例1至对比例3中锂金属电池的性能随着锂盐、第一溶剂、电解液的变化而变化。从实施例5至实施例7、对比例1至对比例2可以看出，当锂盐摩尔浓度和第一溶剂质量百分含量在本申请的范围内，并且A×B满足本申请权利要求1的条件，所制备的锂金属电池具有更好地循环性能和安全性能。
实施例21至实施例26
除了相关制备参数及性能参数如表2所示以外，其余与实施例2相同。
实施例27至实施例28
除了相关制备参数及性能参数如表2所示以外，其余与实施例7相同。
表2
Figure PCTCN2022074525-appb-000006
从实施例21至实施例28可以看出，锂金属电池的循环性能和安全性能随着第二溶剂和第三组分的变化而变化。从实施例22至实施例23可以看出，选用第二溶剂的种类及质量百分含量在本申请范围内的锂金属电池，可以有更好的循环性能和安全性能；第二溶剂和第三组分的种类也会影响锂金属电池的循环性能和安全性能，从实施例26至实施例28可以看出，选用第二溶剂和第三组分的种类在本申请范围内的锂金属电池，循环性能和安全性能得到明显改善。
实施例29至实施例30、实施例35至实施例38
除了相关制备参数及性能参数如表3所示，其余与实施例1相同。
实施例31
除了相关制备参数及性能参数如表3所示，其余与实施例12相同。
实施例32
除了相关制备参数及性能参数如表3所示，其余与实施例9相同。
实施例33
除了相关制备参数及性能参数如表3所示，其余与实施例10相同。
实施例34
除了相关制备参数及性能参数如表3所示，其余与实施例11相同。
表3
  A(mol/L) B(wt％) C D(wt％) E(％) E/D 100圈循环保持率％ 热箱测试(℃)
实施例29 2 25 0.1 5 20 4 86.7 131
实施例30 3 30 0.1 5 20 4 85.5 131
实施例31 2 25 0.01 5 5 1 88.2 135
实施例32 2 25 0.5 5 10 2 87.9 127
实施例33 2 25 1 5 30 6 86.8 127
实施例34 2 25 3 5 35 7 86.1 129
实施例35 3 30 0.1 8 20 2.5 89.3 136
实施例36 3 30 0.1 10 10 1 87.8 134
实施例37 3 30 0.1 10 15 1.5 87.9 133
实施例38 3 30 0.1 15 9 0.6 86.4 128
从实施例29至实施例38可以看出，锂金属电池的循环性能和安全性能随着正极极片孔隙率、孔隙率和电解液质量百分含量的比值的变化而变化。正极极片孔隙率和电解液质量百分含量的比值通常也会影响锂金属电池的循环性能和安全性能，选用E/D的比值在本 申请范围内的锂金属电池，电解液的质量百分含量一定的情况下，锂金属电池中电解液的含量较高时，锂金属电池的循环性能得到明显改善。
以上所述仅为本申请的较佳实施例，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之内。

Claims (13)

  1. 一种锂金属电池，其包括正极极片、负极极片以及电解液，所述电解液包括锂盐和溶剂，所述锂盐的摩尔浓度为Amol/L，且2≤A≤4；所述溶剂包含第一溶剂，基于所述电解液中溶剂的总质量，所述第一溶剂的质量百分含量为B％，满足10≤B≤50；其中，所述A和B满足关系式：40≤A×B≤100。
  2. 根据权利要求1所述的锂金属电池，其中，所述锂盐在所述第一溶剂中的溶解度为Cg/100g，满足：0.01≤C≤5。
  3. 根据权利要求1所述的锂金属电池，其中，所述电解液的总质量占锂金属电池的质量分数为D％，满足：2≤D≤15。
  4. 根据权利要求1所述的锂金属电池，其中，所述锂盐包括高氯酸锂、六氟砷酸锂、六氟磷酸锂、双三氟甲基磺酰亚胺锂、双氟磺酰亚胺锂、二氟草酸硼酸锂、四氟硼酸锂、三氟甲基磺酸锂中的至少一种。
  5. 根据权利要求1所述的锂金属电池，其中，所述第一溶剂包括下列通式所示化合物中的至少一种：
    Figure PCTCN2022074525-appb-100001
    其中，
    R 1、R 2各自独立地选自C 1至C 10烷基、C 2至C 10烯基、C 1至C 10卤代烷基、C 2至C 10硅烷基、C 2至C 10卤代烯基、C 6至C 26芳基、C 6至C 26卤代芳基或C 1至C 10烷氧基；
    R 3至R 8各自独立地选自-F、-H、C 1至C 10卤代烷基或C 2至C 10卤代烯基；
    R 9、R 10各自独立地选自C 1至C 10烷基、C 2至C 10烯基、C 1至C 10卤代烷基、C 2至C 10硅烷基、C 2至C 10卤代烯基、C 6至C 26芳基、C 6至C 26卤代芳基或C 1至C 10卤代烷氧基；
    R 11、R 12各自独立地选自C 1至C 10烷基、C 2至C 10烯基、C 1至C 10卤代烷基、C 2至C 10硅烷基或C 2至C 10卤代烯基；
    R 13、R 14各自独立地选自C 1至C 10烷基、C 2至C 10烯基、C 1至C 10卤代烷基或C 2至C 10卤代烯基。
  6. 根据权利要求1所述的锂金属电池，其中，所述第一溶剂包括下式化合物中的至少一种：
    Figure PCTCN2022074525-appb-100002
  7. 根据权利要求1所述的锂金属电池，其中，所述电解液还包括第二溶剂，所述第二溶剂包括碳酸酯类化合物、羧酸酯类化合物、含硫氧双键的化合物、酸酐、酰胺类化合物、腈类化合物、醚类化合物、硫醚类化合物、磷酸酯类化合物、含有机阳离子的离子液体中的至少一种。
  8. 根据权利要求7所述的锂金属电池，其中，所述碳酸酯类化合物包括碳酸亚乙酯、碳酸亚丙酯、碳酸二甲酯、碳酸二乙酯、碳酸二丙酯、碳酸甲乙酯、碳酸甲丙酯、碳酸亚乙烯酯、氟代碳酸乙烯酯中的至少一种；所述羧酸酯类化合物包括甲酸甲酯、乙酸乙酯、乙酸丙酯、丙酸乙酯、丙酸丙酯、γ-丁内酯中的至少一种；所述含硫氧双键的化合物包括亚硫酸乙烯酯、亚硫酸丙烯酯、亚硫酸二甲酯、亚硫酸二乙酯、硫酸二乙酯、二甲基砜、二乙基砜、二甲基亚砜、二乙基亚砜、环丁砜、N,N-二甲基三氟甲磺酰胺中的至少一种；所述酸酐包括乙酸酐和/或丙酸酐；所述酰胺类化合物包括N-甲基吡咯烷酮、N-甲基甲酰胺、N-甲基乙酰胺、N,N-二甲基甲酰胺中的至少一种；所述腈类化合物包括乙腈、丙腈、丁腈中的至少一种；所述醚类化合物包括四氢呋喃、乙二醇二甲醚、乙二醇二乙醚、乙二醇二丙醚、乙二醇二丁醚、二乙二醇二甲醚、三乙二醇二甲醚、四乙二醇二甲醚中的至少一种；所述硫醚类化合物包括乙硫醚和/或甲硫醚；所述磷酸酯类化合物包括磷酸三甲酯、磷酸三乙酯、2-乙氧基-2-氧-1,3,2-二氧磷杂环戊烷、2-三氟乙氧基-2-氧-1,3,2-二氧磷杂环戊烷中的至少一种；所述含有机阳离子的离子液体包括含1-丁基-3-甲基咪唑基阳离子、1-甲基-1-乙基吡咯烷基阳离子、N-丁基-N-甲基哌啶阳离子的离子液体中的至少一种。
  9. 根据权利要求7所述的锂金属电池，其中，基于所述电解液中溶剂的总质量，所述第二溶剂的质量百分含量为10％至60％。
  10. 根据权利要求1所述的锂金属电池，其中，所述电解液还包含第三组分，所述第三组分包括碳酸乙烯亚乙酯、甲烷二磺酸亚甲酯、4-三氟代甲基碳酸乙烯酯、1,3,2-二噁唑噻吩-2,2-二氧化物、丁二酸酐、丙烯基-1,3-磺酸内酯、双(三甲基硅基)硫酸酯、N-甲基,丁基吡咯烷双三氟甲磺酰亚胺盐、N-甲基,丙基哌啶双三氟甲磺酰亚胺盐、1,2-双(氰乙氧基)乙烷、己二腈、1,3,5-戊三甲腈、反丁烯二腈或1,2,3-三(2-氰乙氧基)丙烷中的至少一种。
  11. 根据权利要求10所述的锂金属电池，其中，基于所述电解液的总质量，所述第三组分的质量百分含量为0.01％至10％。
  12. 根据权利要求1所述的锂金属电池，其中，所述正极极片的孔隙率为E％，满足5≤E≤35；并且0.5≤E/D≤15。
  13. 一种电子装置，其包含权利要求1至12中任一项所述的锂金属电池。
PCT/CN2022/074525 2022-01-28 2022-01-28 锂金属电池及电子装置 WO2023141920A1 (zh)

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