WO2024007143A1 - 二次电池、电池模块、电池包及用电装置 - Google Patents

二次电池、电池模块、电池包及用电装置 Download PDF

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WO2024007143A1
WO2024007143A1 PCT/CN2022/103814 CN2022103814W WO2024007143A1 WO 2024007143 A1 WO2024007143 A1 WO 2024007143A1 CN 2022103814 W CN2022103814 W CN 2022103814W WO 2024007143 A1 WO2024007143 A1 WO 2024007143A1
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sodium
secondary battery
negative electrode
electrolyte
positive electrode
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PCT/CN2022/103814
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English (en)
French (fr)
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秦猛
官英杰
马晴岩
杨惠玲
温严
黄起森
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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 PCT/CN2022/103814 priority Critical patent/WO2024007143A1/zh
Publication of WO2024007143A1 publication Critical patent/WO2024007143A1/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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • 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 field of secondary batteries, and specifically relates to a secondary battery, a battery module, a battery pack and an electrical device.
  • a sodium-ion battery is a secondary battery that relies on the movement of sodium ions between the positive and negative electrodes. It has a similar working principle and manufacturing process to lithium-ion batteries. Compared with lithium-ion batteries, the electrode materials used in sodium-ion batteries are mainly sodium salts, which have the advantages of low cost and abundant resources. However, since sodium ions are larger than lithium ions, there is a large gap in the energy density of sodium-ion batteries compared with lithium-ion batteries. Among them, the anodeless lithium-ion battery uses sodium metal deposited on the negative electrode current collector during the charge and discharge process as the anode, which can effectively improve the sodium-ion battery. However, it has the problem of poor cycle performance and is difficult to be applied in practice.
  • this application provides a secondary battery, battery module, battery pack and electrical device, which can inhibit the growth of sodium dendrites and improve the cycle performance of the secondary battery.
  • One aspect of the present application provides a secondary battery, including:
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, and the positive electrode active material layer contains sodium ion active material;
  • the negative electrode piece includes a negative electrode current collector and a metal film layer disposed on at least one surface of the negative electrode current collector; the nucleation overpotential of sodium on the negative electrode piece is less than or equal to 35mV; optionally, the sodium on the negative electrode piece The nucleation overpotential is less than or equal to 30mV; and
  • An electrolyte is provided between the positive electrode piece and the negative electrode piece, and the electrolyte contains boric acid sodium salt.
  • the positive active material layer of the positive electrode sheet contains sodium ion active material
  • the negative electrode sheet has metal
  • the nucleation potential of sodium is ⁇ 35mV
  • the electrolyte contains boric acid sodium salt
  • the metal has a low overpotential for metallic sodium and works synergistically with the boric acid sodium salt in the electrolyte to induce uniform deposition of sodium and inhibit the growth of sodium dendrites, thereby greatly improving the cycle performance of the above-mentioned secondary battery.
  • the metal film layer includes at least one metal selected from aluminum, nickel, chromium, bismuth, tin, indium and antimony;
  • the metal film layer includes at least one metal of aluminum, nickel and chromium;
  • the metal film layer includes an alloy composed of at least two types of aluminum, nickel, chromium, bismuth, tin, indium and antimony.
  • the above metal has a low overpotential for metallic sodium, which is beneficial to the uniform deposition of metallic sodium on the metal film layer.
  • the thickness of the metal film layer is 10 nm to 300 nm;
  • the thickness of the metal film layer is 30 nm to 200 nm.
  • the above-mentioned nanometer-thick metal film layer can suppress sodium dendrites and improve cycle performance while ensuring high energy density.
  • the metal film layer is prepared on the surface of the negative electrode current collector using a magnetron sputtering method or an evaporation method.
  • the metal film layer prepared by magnetron sputtering method or evaporation method has good uniformity and density, which is conducive to further improving the uniformity of sodium metal deposition.
  • the boric acid sodium salts include sodium difluoroborate, sodium tetrafluoroborate, sodium dioxaloborate, sodium difluoroxaloborate, sodium tetraphenylborate, sodium tetracyanoborate, tetrakis(trifluoroborate) Sodium methyl)borate, sodium bis(trifluoromethyl)difluoroborate, sodium pentafluoroethyltrifluoroborate, sodium dicyanooxaloborate, sodium methoxytricyanoborate, ethoxytricyanoborate At least one of sodium, sodium tetramethoxyborate, sodium tetraethoxyborate and sodium cyanotris(2,2,2trifluoroethyl)borate;
  • the boric acid sodium salt includes at least one of sodium difluoroxaloborate and sodium dioxaloborate.
  • boric acid anions of the above-mentioned boric acid sodium salt and the metal film layer of the negative electrode piece work together to form a solid electrolyte interface (SEI) film on the surface of the negative electrode piece, improve the sodium deposition kinetics, and facilitate the uniform deposition of sodium.
  • SEI solid electrolyte interface
  • the electrolyte is an electrolyte; optionally, the solvent in the electrolyte includes an ether solvent.
  • Ether solvent molecules can build a stable electrode-electrolyte interface on the surface of the negative electrode sheet, forming a stable solid electrolyte interface (SEI) film and reducing electrochemical polarization.
  • SEI solid electrolyte interface
  • the ether solvent includes ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, At least one of 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether;
  • the ether solvent includes ethylene glycol dimethyl ether.
  • the molar concentration of the boric acid sodium salt is 0.05 mol/L to 8 mol/L;
  • the molar concentration of the boric acid sodium salt is 0.1 mol/L to 2 mol/L.
  • the molar concentration of sodium salt in the electrolyte is usually 0.5 mol/L to 8 mol/L.
  • boric acid sodium salt can be used as the main salt or additive in the electrolyte.
  • the electrolyte further includes sodium perchlorate, sodium hexafluorophosphate, sodium hexafluoroarsenate, sodium trifluoroacetate, sodium trifluoromethanesulfonate, and sodium bis(fluorosulfonyl)imide. and at least one of sodium bis(trifluoromethanesulfonyl)imide.
  • this application also provides a battery module, including the above-mentioned secondary battery.
  • this application also provides a battery pack, including the above-mentioned battery module.
  • the present application also provides an electrical device, which includes at least one of the above-mentioned secondary battery, the above-mentioned battery module, and the above-mentioned battery pack.
  • the secondary battery Used to provide electrical energy.
  • Figure 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • Figure 2 is an exploded view of the secondary battery according to an embodiment of the present application shown in Figure 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 Figure 4;
  • Figure 6 is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment of the present application
  • the present application provides a secondary battery, a battery module, a battery pack and an electrical device using the secondary battery.
  • This kind of secondary battery is suitable for various electrical devices that use batteries, such as mobile phones, portable devices, laptops, battery cars, electric toys, power tools, electric cars, ships and spacecraft.
  • spacecraft include aircraft, rockets , space shuttles and spacecrafts, etc.
  • a secondary battery in one embodiment, includes a positive electrode piece, a negative electrode piece and an electrolyte.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the negative electrode piece includes a negative electrode current collector and a metal film layer disposed on at least one surface of the negative electrode current collector; the nucleation overpotential of sodium on the negative electrode piece is less than or equal to 35 mV. Optionally, the nucleation overpotential of sodium on the negative electrode piece is less than or equal to 30 mV.
  • the electrolyte contains boric acid sodium 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 negative electrode will undergo an electrochemical reaction in which the electrons from sodium ions are reduced to sodium metal, so it has a higher energy density.
  • uneven deposition of sodium metal on the surface of the negative electrode sheet can easily generate sodium dendrites, thus affecting the cycle performance of the secondary battery.
  • the positive active material layer of the positive electrode sheet contains sodium ion active material
  • the negative electrode sheet has metal
  • the nucleation potential of sodium is ⁇ 35mV
  • the electrolyte contains boric acid sodium salt
  • the metal has a low overpotential for metallic sodium and works synergistically with the boric acid sodium salt in the electrolyte to induce uniform deposition of sodium and inhibit 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 metal film layer includes at least one metal selected from the group consisting of aluminum, nickel, chromium, bismuth, tin, indium and antimony. Further, the metal film layer includes at least one metal of aluminum, nickel and chromium. In some embodiments, the metal film layer includes an alloy composed of at least two of aluminum, nickel, chromium, bismuth, tin, indium and antimony. Optionally, the metal film layer includes nickel-chromium alloy. The above metal has a low overpotential for metallic sodium, which is beneficial to the uniform deposition of metallic sodium on the metal film layer.
  • the thickness of the metal film layer ranges from 10 nm to 300 nm.
  • the thickness of the metal film layer is 10nm, 20nm, 30nm, 50nm, 100nm, 150nm, 200nm, 250nm or 300nm. Further, the thickness of the metal film layer is 30 nm to 200 nm.
  • the above-mentioned nanometer-thick metal film layer can suppress sodium dendrites and improve cycle performance while ensuring high energy density. If the thickness of the metal film is too large, the energy density of the secondary battery will be reduced; if the thickness of the metal film is too small, the uniformity of sodium deposition on the surface of the negative electrode will be poor.
  • the metal film layer is prepared on the surface of the negative electrode current collector using a magnetron sputtering method or an evaporation method.
  • the metal film layer prepared by magnetron sputtering method or evaporation method has good uniformity and density, which is conducive to further improving the uniformity of sodium metal deposition.
  • the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector.
  • the positive active material layer includes a positive 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 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 such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy on a polymer material substrate.
  • Polymer material substrates include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE) ) and other base materials.
  • 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.
  • the positive active material layer optionally further includes a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene tripolymer. At least one of a meta-copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer and a fluorine-containing acrylate resin.
  • the positive active material layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive active materials, conductive agents, binders and any other components, are dispersed 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 electrolyte includes boric acid sodium salt.
  • the type of electrolyte in this application can be selected according to needs.
  • the electrolyte can be liquid, gel, or completely solid.
  • boric acid sodium salts include sodium difluoroborate, sodium tetrafluoroborate (NaBF 4 ), sodium dioxaloborate, sodium difluoroxaloborate, and sodium tetraphenylborate (NaB(C 6 H 5 ) 4 ), sodium tetracyanoborate, sodium tetrakis(trifluoromethyl)borate, sodium bis(trifluoromethyl)difluoroborate, sodium pentafluoroethyltrifluoroborate, sodium dicyanooxalateborate, methoxytris At least one of sodium cyanoborate, sodium ethoxytricyanoborate, sodium tetramethoxyborate, sodium tetraethoxyborate and sodium cyanotris(2,2,2trifluoroethyl)borate.
  • boric acid sodium salt includes at least one of sodium difluoroxaloborate and sodium dioxaloborate.
  • boric acid anions of the above-mentioned boric acid sodium salt work synergistically with the metal film layer of the negative electrode sheet to form a solid electrolyte interface (SEI) film on the surface of the negative electrode sheet, improve the sodium deposition kinetics, and facilitate the uniform deposition of sodium, thus inhibiting Sodium dendrite growth improves the cycle performance of secondary batteries.
  • SEI solid electrolyte interface
  • the electrolyte is an electrolyte solution.
  • the solvent in the electrolyte includes ether solvent. Ether solvent molecules can build a stable electrode-electrolyte interface on the surface of the negative electrode sheet, forming a stable solid electrolyte interface (SEI) film and reducing electrochemical polarization.
  • SEI solid electrolyte interface
  • the ether solvents include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1, At least one of 3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether;
  • the ether solvent includes ethylene glycol dimethyl ether.
  • the molar concentration of boric acid sodium salt in the electrolyte is 0.05 mol/L to 8 mol/L.
  • the molar concentration of boric acid sodium salt is 0.05mol/L, 0.1mol/L, 0.5mol/L, 1mol/L, 2mol/L, 4mol/L, 5mol/L, 6mol/L or 8mol/L .
  • the molar concentration of the boric acid sodium salt is 0.1 mol/L to 2 mol/L.
  • the molar concentration of sodium salt in the electrolyte is 0.5 mol/L to 8 mol/L.
  • boric acid sodium salt can be used as the main salt or additive in the electrolyte.
  • the electrolyte further includes sodium perchlorate (NaClO 4 ), sodium hexafluorophosphate (NaPF 6 ), sodium hexafluoroarsenate (NaAsF 6 ), sodium trifluoroacetate (CF 3 COONa), trifluoroacetate Sodium methanesulfonate (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]) at least one.
  • sodium perchlorate NaClO 4
  • NaPF 6 sodium hexafluorophosphate
  • NaAsF 6 sodium hexafluoroarsenate
  • CF 3 COONa sodium trifluoroacetate
  • Sodium methanesulfonate NaSO 3 CF 3
  • the solvent in the electrolyte further includes ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate Ester, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ⁇ -butyrolactone, 1,3-propane sultone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate At least one of ester, propyl propionate, ethyl butyrate and dimethyl sulfoxide.
  • 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.
  • a separator film 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 formed 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.
  • the secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art 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. The specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 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 can be used as a power source for the power-consuming device, or as an energy storage unit of the power-consuming device.
  • Electrical devices may include mobile equipment, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • mobile devices can be, for example, mobile phones, laptops, etc.; electric vehicles can be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc. , but not limited to this.
  • secondary batteries, battery modules or battery packs can be selected according to its usage requirements.
  • FIG. 6 shows an electrical device 6 as an example.
  • the electric device 6 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like.
  • 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.
  • Preparation of positive electrode sheet Fully dissolve 10wt% polyvinylidene fluoride (PVDF) binder in N-methylpyrrolidone (NMP), add 10wt% carbon black conductive agent and 80wt% positive electrode active material (Na 4 Fe 3 ( PO 4 ) 2 (P 2 O 7 )) is made into a uniformly dispersed slurry. Spread the slurry evenly on the surface of the aluminum foil and then transfer it to a vacuum drying oven to dry completely. The obtained pole piece is rolled and then punched to obtain a positive electrode piece.
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • P 2 O 7 80wt% positive electrode active material
  • Preparation of the negative electrode plate A metal film layer is deposited on the surface of the negative electrode copper current collector by magnetron sputtering.
  • the type and thickness of the metal film layer are recorded in Table 1.
  • the negative copper current collector is placed in a vacuum chamber through a transmission mechanism, and the target is placed in a metal vapor generator.
  • the metal vapor generator is placed in the vacuum chamber.
  • the ejection flow rate of the metal vapor is 500ml/min (corresponding to the metal film thickness of 100nm in Example 1), so that the negative electrode copper current collector is immersed in the metal vapor. .
  • the vacuum degree can be achieved by the vacuum unit, and the vacuum degree is ⁇ 8 ⁇ 10 2 Pa.
  • the threshold requirement of the vacuum degree can be achieved by setting the parameters of the vacuum unit.
  • the thickness of the metal film layer is controlled by controlling the flow rate of the metal vapor. Specifically, when the thickness of the metal film layer is 10nm, the ejection flow rate of the metal vapor is 50ml/min; when the thickness of the metal film layer is 300nm, the ejection flow rate of the metal vapor is It is 1500ml/min; the target material is selected according to the type of metal film layer in Table 1. The corresponding metal or alloy is selected.
  • the time of magnetron sputtering can be controlled by the tape transport speed of the transmission mechanism. When the above flow window is determined, the tape transport speed is 300m/min.
  • Electrolyte preparation In an argon atmosphere glove box (H 2 O ⁇ 0.1ppm, O 2 ⁇ 0.1ppm), dissolve the sodium salt in the organic solvent ethylene glycol dimethyl ether, stir evenly, and obtain the electrolyte, sodium salt The types and concentrations are recorded in Table 1.
  • Isolation film Polypropylene film is used as the isolation film.
  • Secondary battery preparation Stack the positive electrode sheet, isolation film, and negative electrode sheet in order so that the isolation film is between the positive electrode and the negative electrode current collector to play the role of isolation. Inject the electrolyte to assemble the secondary battery.
  • the prepared secondary battery was charged to 100 ⁇ A at a constant current of 0.1 C at 25°C, and the most negative potential obtained during the process was recorded as the nucleation overpotential.
  • the prepared secondary battery was charged to 3.7V at a constant current of 1/3C at 25°C, and then charged at a constant voltage of 3.7V until the current dropped to 0.05C to obtain the first charge capacity (Cc1); then charged at a constant voltage of 1/3C Discharge to 2.5V with a constant current to obtain the first discharge capacity (Cd1), and calculate the Coulombic efficiency of the secondary battery according to the following formula.
  • the secondary battery Charge the secondary battery to 3.7V at 25°C with a constant current of 1C, then charge with a constant voltage of 3.7V until the current drops to 0.05C, and then discharge it with a constant current of 1C to 2.5V to obtain the first cycle discharge capacity (Cd1 ); after repeated charging and discharging to the nth cycle, the discharge capacity of the secondary battery after n cycles is obtained, recorded as Cdn, and the capacity retention rate of the secondary battery is calculated according to the following formula:
  • Capacity retention rate discharge capacity after n cycles (Cdn)/discharge capacity in the first cycle (Cd1).
  • Example 1 18 95.7 88.2 none Example 2 20 94.2 87.1 none Example 3 twenty two 93.6 86.4 none Example 4 twenty three 92.3 85.2 none Example 5 twenty four 91.9 84.6 none Example 6 twenty four 91.6 84.1 none Example 7 25 90.9 83.6 none Example 8 25 90.5 83.1 none Example 9 twenty four 91.5 84.3 none Example 10 25 91.1 84.0 none Example 11 26 90.3 83.7 none Example 12 twenty three 92.9 86.5 none Example 13 twenty four 92.1 85.8 none Example 14 29 88.4 81.2 none Example 15 twenty three 92.3 84.4 none Comparative example 1 37 82.9 75.5 slight Comparative example 2 38 81.2 71.6 serious Comparative example 3 39 80.3 70.2 serious Comparative example 4 40 79.1 69.4 serious Comparative example 5 36 84.5 77.9 slight
  • the metal film layer is aluminum, nickel, chromium or nickel-chromium alloy, and the nucleation overpotential of the negative electrode plate is low, only 18mV to 23mV.
  • the Coulombic efficiency is 92.3% to 95.7%, indicating that during the charge and discharge process, the irreversible loss of active sodium due to sodium dendrite growth is less; the capacity retention rate after 100 cycles is 85.2% to 88.2%, which has good performance. Cycle performance.
  • the thickness of the metal film layer in Example 9 is 10 nm
  • the thickness of the metal film layer in Example 10 is 300 nm.
  • the Coulombic efficiency and the capacity retention rate of the secondary batteries in Examples 9 to 10 are slightly lower after 100 cycles.
  • the secondary battery of Example 1 Therefore, by controlling the thickness of the metal film layer between 30nm and 200nm, the cycle performance of the secondary battery will be better.
  • Example 11 The difference between Examples 11 to 14 and Example 1 is that the molar concentration of NaDFOB is different. From Examples 1 and 11 to 14, it can be seen that the molar concentration of boric acid sodium salt in the electrolyte will also affect the nucleation overpotential of the negative electrode plate. , when the molar concentration of boric acid sodium salt is 0.1 mol/L ⁇ 2 mol/L, the cycle performance of the secondary battery is better.
  • Comparative Example 4 is a traditional sodium-ion battery without anode.
  • the difference between Comparative Example 2 and Comparative Example 4 is that there is a manganese metal film layer on the negative electrode current collector.
  • the difference between Comparative Example 1 and Comparative Example 2 is that the sodium salt in the electrolyte is replaced by NaDFOB ;
  • the difference between Comparative Example 3 and Comparative Example 4 is that the sodium salt in the electrolyte is replaced by NaDFOB;
  • the difference between Comparative Example 5 and Comparative Example 4 is that there is an aluminum metal film layer on the negative electrode current collector.
  • the Coulombic efficiency and the capacity retention rate of the secondary battery of Comparative Examples 1 to 3 and 5 after 100 cycles are slightly improved.
  • there are still sodium dendrites visible to the naked eye on the negative electrode sheet. the effect of inhibiting the growth of sodium dendrites is poor.

Abstract

本申请提供了一种二次电池，包括正极极片、负极极片及电解质。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。负极极片包括负极集流体及设于负极集流体至少一个表面上的金属膜层。负极极片上钠的成核过电位小于等于35mV。电解质设于正极极片与负极极片之间，电解质中包含有硼酸类钠盐。

Description

二次电池、电池模块、电池包及用电装置 技术领域
本申请涉及二次电池领域，具体涉及一种二次电池、电池模块、电池包及用电装置。
背景技术
钠离子电池是一种依靠钠离子在正极和负极之间移动来工作的二次电池，其具有与锂离子电池相似的工作原理和制造工艺。相比锂离子电池，钠离子电池中使用的电极材料主要是钠盐，具有成本低廉、资源丰富等优势。但由于钠离子比锂离子更大，钠离子电池的能量密度与锂离子电池相比存在较大的差距。其中，无负极锂离子电池以充放电过程中在负极集流体沉积的钠金属作为负极，可有效提升钠离子电池，但其存在循环性能差的问题，难以实际应用。
发明内容
基于上述问题，本申请提供一种二次电池、电池模块、电池包及用电装置，能够抑制钠枝晶生长，改善二次电池循环性能。
本申请的一个方面，提供了一种二次电池，包括：
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；
负极极片，包括负极集流体及设于所述负极集流体至少一个表面上的金属 膜层；所述负极极片上钠的成核过电位小于等于35mV；可选地，所述负极极片上钠的成核过电位小于等于30mV；及
电解质，设于所述正极极片与所述负极极片之间，所述电解质中包含有硼酸类钠盐。
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，且负极极片具有金属，钠的成核电位≤35mV及电解质中包含有硼酸类钠盐，金属膜层对金属钠具有较低的过电位，并与电解质中的硼酸类钠盐协同作用，诱导钠均匀沉积，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。
在其中一些实施例中，所述金属膜层包括铝、镍、铬、铋、锡、铟及锑中的至少一种金属；
可选地，所述金属膜层包括铝、镍及铬的至少一种金属；
可选地，所述金属膜层包括铝、镍、铬、铋、锡、铟及锑中的至少两种组成的合金。
上述金属对于金属钠具有较低的过电位，有利于金属钠在金属膜层的均匀沉积。
在其中一些实施例中，所述金属膜层的厚度为10nm～300nm；
可选地，所述金属膜层的厚度为30nm～200nm。
上述纳米级厚度的金属膜层能够在抑制钠枝晶，改善循环性能的同时，保证较高的能量密度。
在其中一些实施例中，所述金属膜层采用磁控溅射方法或者蒸镀方法制备在所述负极集流体的表面上。
通过磁控溅射方法或者蒸镀方法制备的金属膜层均匀性、致密性较好，有利于进一步提升钠金属沉积均匀性。
在其中一些实施例中，所述硼酸类钠盐包括二氟硼酸钠、四氟硼酸钠、二草酸硼酸钠、二氟草酸硼酸钠、四苯硼酸钠、四氰基硼酸钠、四(三氟甲基)硼酸钠、双(三氟甲基)二氟硼酸钠、五氟乙基三氟硼酸钠、二氰基草酸硼酸钠、甲氧基三氰基硼酸钠、乙氧基三氰基硼酸钠、四甲氧基硼酸钠、四乙氧基硼酸钠及氰基三(2,2,2三氟乙基)硼酸钠中的至少一种；
可选地，所述硼酸类钠盐包括二氟草酸硼酸钠及二草酸硼酸钠中的至少一种。
上述硼酸类钠盐的硼酸类阴离子与负极极片金属膜层协同发挥作用，能够在负极极片表面形成固态电解质界面(SEI)膜，改善钠沉积动力学，有利于钠的均匀沉积。
在其中一些实施例中，所述电解质为电解液；可选地，所述电解质中的溶剂包括醚类溶剂。
醚类溶剂分子可以在负极极片表面构建稳定的电极-电解液界面，形成稳定的固态电解质界面(SEI)膜，减小电化学极化。
在其中一些实施例中，所述醚类溶剂包括乙二醇二甲醚、乙二醇二乙醚、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、四氢呋喃、甲基四氢呋喃、二苯醚及冠醚中的至少一种；
可选地，所述醚类溶剂包括乙二醇二甲醚。
在其中一些实施例中，在所述电解质中，所述硼酸类钠盐的摩尔浓度为0.05mol/L～8mol/L；
可选地，所述硼酸类钠盐的摩尔浓度为0.1mol/L～2mol/L。
电解质中钠盐的摩尔浓度通常为0.5mol/L～8mol/L，在本申请中，硼酸类钠盐可作为电解质中的主盐或者添加剂。
在其中一些实施例中，所述电解质还包括高氯酸钠、六氟磷酸钠、六氟砷酸钠、三氟乙酸钠、三氟甲基磺酸钠、双(氟磺酰)亚胺钠及双(三氟甲基磺酰)亚胺钠中的至少一种。
第二方面，本申请还提供了一种电池模块，包含如上述的二次电池。
第三方面，本申请还提供了一种电池包，包含如上述的电池模块。
第四方面，本申请还提供了一种用电装置，所述用电装置包括如上述的二次电池、如上述的电池模块及如上述的电池包中的至少一种，所述二次电池用于提供电能。
本申请的一个或多个实施例的细节在下面的附图和描述中提出，本申请的其它特征、目的和优点将从说明书、附图及权利要求书变得明显。
附图说明
图1为本申请一实施方式的二次电池的示意图；
图2为图1所示的本申请一实施方式的二次电池的分解图；
图3为本申请一实施方式的电池模块的示意图；
图4为本申请一实施方式的电池包的示意图；
图5为图4所示的本申请一实施方式的电池包的分解图；
图6为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；
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；6用电装置。
为了更好地描述和说明这里公开的那些发明的实施例和/或示例，可以参考一副或多副附图。用于描述附图的附加细节或示例不应当被认为是对所公开的发明、目前描述的实施例和/或示例以及目前理解的这些发明的最佳模式中的任何一者的范围的限制。
具体实施方式
为了便于理解本申请，下面将参照相关附图对本申请进行更全面的描述。附图中给出了本申请的较佳实施例。但是，本申请可以以许多不同的形式来实现，并不限于本文所描述的实施例。相反地，提供这些实施例的目的是使对本申请的公开内容的理解更加透彻全面。
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。本文中在本申请的说明书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。本文所使用的术语“和/或”包括一个或多个相关的所列项目的任意的和所有的组合。
本申请提供了一种二次电池、和使用该二次电池的电池模块、电池包及用电装置。这种二次电池适用于各种使用电池的用电装置，例如手机、便携式设备、笔记本电脑、电瓶车、电动玩具、电动工具、电动汽车、船舶和航天器等，例如，航天器包括飞机、火箭、航天飞机和宇宙飞船等。
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、负极极片及电解质。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。
其中，负极极片包括负极集流体及设于负极集流体至少一个表面上的金属膜层；负极极片上钠的成核过电位小于等于35mV。可选地，负极极片上钠的成核过电位小于等于30mV。电解质中包含有硼酸类钠盐。
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，因而具有较高的能量密度。然而，负极极片表面的钠金属沉积不均容易生成钠枝晶，从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，且负极极片具有金属，钠的成核电位≤35mV及电解质中包含有硼酸类钠盐，金属膜层对金属钠具有较低的过电位，并与电解质中的硼酸类钠盐协同作用，诱导钠均匀沉积，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。
在其中一些实施例中，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。
在其中一些实施例中，金属膜层包括铝、镍、铬、铋、锡、铟及锑中的至少一种金属。进一步地，金属膜层包括铝、镍及铬的至少一种金属。在其中一些实施例中，金属膜层包括铝、镍、铬、铋、锡、铟及锑中的至少两种组成的合金。可选地，金属膜层包括镍铬合金。上述金属对于金属钠具有较低的过电位，有利于金属钠在金属膜层的均匀沉积。
在其中一些实施例中，金属膜层的厚度为10nm～300nm。可选地，金属膜层的厚度为10nm、20nm、30nm、50nm、100nm、150nm、200nm、250nm或者300nm。进一步地，金属膜层的厚度为30nm～200nm。上述纳米级厚度的金属膜层能够在抑制钠枝晶，改善循环性能的同时，保证较高的能量密度。金属膜层厚度过大，会降低二次电池的能量密度；金属膜层的厚度过小，则负极表面钠沉积均匀性较差。
在其中一些实施例中，金属膜层采用磁控溅射方法或者蒸镀方法制备在负极集流体的表面上。通过磁控溅射方法或者蒸镀方法制备的金属膜层均匀性、致密性较好，有利于进一步提升钠金属沉积均匀性。
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，正极活性材料层包括正极活性材料。
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。
在其中一些实施例中，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铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等金属材料形成在高分子材料基材上而形成。高分子材料基材包括如聚丙烯(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。
在其中一些实施例中，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。
在其中一些实施例中，正极活性材料层还可选地包括粘结剂。作为示例，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。
在其中一些实施例中，正极活性材料层还可选地包括导电剂。作为示例，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。
在其中一些实施例中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、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。本申请中电解质包含有硼酸类钠盐。本申请中对于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。
在其中一些实施例中，硼酸类钠盐包括二氟硼酸钠、四氟硼酸钠(NaBF 4)、二草酸硼酸钠、二氟草酸硼酸钠、四苯硼酸钠(NaB(C 6H 5) 4)、四氰基硼酸钠、四(三氟甲基)硼酸钠、双(三氟甲基)二氟硼酸钠、五氟乙基三氟硼酸钠、二氰基草酸硼酸钠、甲氧基三氰基硼酸钠、乙氧基三氰基硼酸钠、四甲氧基硼酸钠、四乙氧基硼酸钠及氰基三(2,2,2三氟乙基)硼酸钠中的至少一种。
进一步地，硼酸类钠盐包括二氟草酸硼酸钠及二草酸硼酸钠中的至少一种。
上述硼酸类钠盐的硼酸类阴离子与负极极片金属膜层协同发挥作用，能够在负极极片表面形成固态电解质界面(SEI)膜，改善钠沉积动力学，有利于钠的均匀沉积，从而抑制钠枝晶生长，改善二次电池的循环性能。
在其中一些实施例中，电解质为电解液。进一步地，电解质中的溶剂包括醚类溶剂。醚类溶剂分子可以在负极极片表面构建稳定的电极-电解液界面，形成稳定的固态电解质界面(SEI)膜，减小电化学极化。
在其中一些实施例中，醚类溶剂包括乙二醇二甲醚、乙二醇二乙醚、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、四氢呋喃、甲基四氢呋喃、二苯醚及冠醚中的至少一种；
可选地，醚类溶剂包括乙二醇二甲醚。
在其中一些实施例中，在电解质中，硼酸类钠盐的摩尔浓度为0.05mol/L～8 mol/L。可选地，硼酸类钠盐的摩尔浓度为0.05mol/L、0.1mol/L、0.5mol/L、1mol/L、2mol/L、4mol/L、5mol/L、6mol/L或者8mol/L。进一步地，硼酸类钠盐的摩尔浓度为0.1mol/L～2mol/L。
通常地，电解质中钠盐的摩尔浓度为0.5mol/L～8mol/L，在本申请中，硼酸类钠盐可作为电解质中的主盐或者添加剂使用。
在其中一些实施例中，电解质还包括高氯酸钠(NaClO 4)、六氟磷酸钠(NaPF 6)、六氟砷酸钠(NaAsF 6)、三氟乙酸钠(CF 3COONa)、三氟甲基磺酸钠(NaSO 3CF 3)、双(氟磺酰)亚胺钠(Na[(FSO 2) 2N])及双(三氟甲基磺酰)亚胺钠(Na[(CF 3SO 2) 2N])中的至少一种。
在其中一些实施例中，电解质中的溶剂还包括碳酸乙烯酯、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。
在其中一些实施例中，电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
隔离膜
在其中一些实施例中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在其中一些实施例中，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。
在其中一些实施例中，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。
在其中一些实施例中，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。
在其中一些实施例中，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。
在其中一些实施例中，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能够盖设于开口，以封闭容纳腔。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。
在其中一些实施例中，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。
在其中一些实施例中，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，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。二次电池、电池模块、或电池包可以用作用电装置的电源，也可以用作用电装置的能量存储单元。用电装置可以包括移动设备、电动车辆、电气列车、船舶及卫星、储能系统等，但不限于此。其中，移动设备例如可以是手机、笔记本电脑等；电动车辆例如可以是纯电动车、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，但不限于此。
作为用电装置，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6。该用电装置6为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和 高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
正极极片制备：将10wt％聚偏氟乙烯(PVDF)粘结剂充分溶解于N-甲基吡咯烷酮(NMP)中，加入10wt％炭黑导电剂与80wt％正极活性材料(Na 4Fe 3(PO 4) 2(P 2O 7))制成分散均匀的浆料。将浆料均匀涂敷在铝箔表面，然后转移到真空干燥箱中完全干燥。将得到的极片进行辊压，然后进行冲切，得到正极极片。
负极极片制备：通过磁控溅射方法在负极铜集流体表面沉积一层金属膜层，金属膜层的种类及厚度记录在表1中。具体地，通过传输机构将负极铜集流体置于一真空室内，同时将靶材置于一金属蒸气发生器内，金属蒸气发生器设置在真空室内，当真空室内的真空度达到阈值要求后，靶材在金属蒸气发生器中持续熔化、蒸发形成金属蒸气，金属蒸气的喷出流量为500ml/min(对应实施例1中金属膜层厚度为100nm)，使负极铜集流体浸于金属蒸气中。真空度可通过真空机组实现，真空度≤8×10 2Pa，真空度的阈值要求可通过设置真空机组的参数实现。通过控制金属蒸气的流量来控制金属膜层的厚度，具体地，金属膜层厚度为 10nm时，金属蒸气的喷出流量为50ml/min；金属膜层厚度为300nm时，金属蒸气的喷出流量为1500ml/min；靶材根据表1中金属膜层的种类选用对应的金属或者合金。通过传输机构的走带速度可控制磁控溅射的时间，在上述流量窗口确定的情况下，走带速度为300m/min。
电解液制备：在氩气气氛手套箱中(H 2O<0.1ppm，O 2<0.1ppm)，将钠盐溶解于有机溶剂乙二醇二甲醚中，搅拌均匀，得到电解液，钠盐的种类及浓度记录在表1中。
隔离膜：以聚丙烯膜作为隔离膜。
二次电池制备：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、负极集流体之间，起到隔离的作用，注入电解液组装成二次电池。
表1实施例1～15及对比例1～5的二次电池的组成
Figure PCTCN2022103814-appb-000001
Figure PCTCN2022103814-appb-000002
测试部分：
成核过电位：
将制得的二次电池在25℃下以0.1C的恒定电流充电至100μA，过程中得到的最负电势记录为成核过电位。
库伦效率测试：
将制得的二次电池在25℃下以1/3C的恒定电流充电至3.7V，之后以3.7V恒压充电至电流降到0.05C，得到首次充电容量(Cc1)；再以1/3C的恒定电流放电至2.5V，得到首次放电容量(Cd1)，并按照下式计算二次电池库伦效率。
二次电池库伦效率＝首次放电容量(Cd1)/首次充电容量(Cc1)。
容量保持率测试：
将二次电池在25℃下以1C的恒定电流充电至3.7V，之后以3.7V恒压充电至电流降到0.05C，再以1C的恒定电流放电至2.5V，得到首圈放电容量(Cd1)；如此反复充放电至第n圈，得二次电池循环n圈后的放电容量，记为Cdn，并按照下式计算二次电池容量保持率：
容量保持率＝循环n圈后的放电容量(Cdn)/首圈放电容量(Cd1)。
钠枝晶形成测试：
将循环100圈后的二次电池在手套箱中(氩气气氛，H 2O<0.1ppm，O 2<0.1ppm)进行拆解，通过肉眼观察负极极片表面形貌，确定是否有钠枝晶生成。
实施例1～15及对比例1～5的二次电池的测试结果记录在表2中。
表2实施例1～15及对比例1～5的二次电池的电化学性能
编号 成核过电位 库伦效率(％) 循环100圈后容 钠枝晶情况
  (mV)   量保持率(％)  
实施例1 18 95.7 88.2 无
实施例2 20 94.2 87.1 无
实施例3 22 93.6 86.4 无
实施例4 23 92.3 85.2 无
实施例5 24 91.9 84.6 无
实施例6 24 91.6 84.1 无
实施例7 25 90.9 83.6 无
实施例8 25 90.5 83.1 无
实施例9 24 91.5 84.3 无
实施例10 25 91.1 84.0 无
实施例11 26 90.3 83.7 无
实施例12 23 92.9 86.5 无
实施例13 24 92.1 85.8 无
实施例14 29 88.4 81.2 无
实施例15 23 92.3 84.4 无
对比例1 37 82.9 75.5 轻微
对比例2 38 81.2 71.6 严重
对比例3 39 80.3 70.2 严重
对比例4 40 79.1 69.4 严重
对比例5 36 84.5 77.9 轻微
从表2相关数据可以看出，与对比例1～5的二次电池相比，实施例1～15的二次电池的成核过电位为18mV～29mV，在循环100圈之后未观察到钠枝晶情况，库伦效率为88.4％～95.7％，循环100圈后，容量保持率为81.2％～88.2％，能够有效地抑制钠枝晶生成，二次电池的循环性能提升。
从实施例1～10可以看出，实施例1～4中金属膜层为铝、镍、铬或镍铬合金，负极极片的成核过电位较低，仅18mV～23mV。库伦效率为92.3％～95.7％，说明在充放电过程中，由于钠枝晶生长等导致的活性钠的不可逆损失较少；循环100圈后容量保持率为85.2％～88.2％，具有较好的循环性能。与实施例1相比，实施例9中金属膜层厚度为10nm，实施例10中金属膜层厚度为300nm，实施例9～10二次电池的库伦效率及循环100圈的容量保持率略低于实施例1的二次电池。因此控制金属膜层的厚度为30nm～200nm之间，二次电池的循环性能更 佳。
实施例11～14与实施例1的区别在于NaDFOB的摩尔浓度不同，从实施例1、11～14可以看出，电解质中硼酸类钠盐的摩尔浓度也会影响负极极片的成核过电位，硼酸类钠盐的摩尔浓度为0.1mol/L～2mol/L时，二次电池的循环性能更佳。
对比例4为传统无负极钠离子电池，对比例2与对比例4的区别在于，负极集流体上具有锰金属膜层；对比例1与对比例2的区别在于，电解质中钠盐替换为NaDFOB；对比例3与对比例4的区别在于，电解质中钠盐替换为NaDFOB；对比例5与对比例4的区别在于，负极集流体上具有铝金属膜层。与对比例4的二次电池相比，对比例1～3、5的二次电池的库伦效率及循环100圈的容量保持率略有提升，然而负极极片上仍有肉眼可观察的钠枝晶，抑制钠枝晶生长的效果较差。
以上所述实施例的各技术特征可以进行任意的组合，为使描述简洁，未对上述实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。
以上所述实施例仅表达了本申请的几种实施方式，其描述较为具体和详细，但并不能因此而理解为对发明专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本申请构思的前提下，还可以做出若干变形和改进，这些都属于本申请的保护范围。因此，本申请专利的保护范围应以所附权利要求为准。

Claims (12)

  1. 一种二次电池，其特征在于，包括：
    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；
    负极极片，包括负极集流体及设于所述负极集流体至少一个表面上的金属膜层；所述负极极片上钠的成核过电位小于等于35mV；可选地，所述负极极片上钠的成核过电位小于等于30mV；及
    电解质，设于所述正极极片与所述负极极片之间，所述电解质中包含有硼酸类钠盐。
  2. 根据权利要求1所述的二次电池，其特征在于，所述金属膜层包括铝、镍、铬、铋、锡、铟及锑中的至少一种金属；
    可选地，所述金属膜层包括铝、镍及铬的至少一种金属；
    可选地，所述金属膜层包括铝、镍、铬、铋、锡、铟及锑中的至少两种组成的合金。
  3. 根据权利要求1或2所述的二次电池，其特征在于，所述金属膜层的厚度为10nm～300nm；
    可选地，所述金属膜层的厚度为30nm～200nm。
  4. 根据权利要求1～3任一项所述的二次电池，其特征在于，所述金属膜层采用磁控溅射方法或者蒸镀方法制备在所述负极集流体的表面上。
  5. 根据权利要求1～4任一项所述的二次电池，其特征在于，所述硼酸类钠盐包括二氟硼酸钠、四氟硼酸钠、二草酸硼酸钠、二氟草酸 硼酸钠、四苯硼酸钠、四氰基硼酸钠、四(三氟甲基)硼酸钠、双(三氟甲基)二氟硼酸钠、五氟乙基三氟硼酸钠、二氰基草酸硼酸钠、甲氧基三氰基硼酸钠、乙氧基三氰基硼酸钠、四甲氧基硼酸钠、四乙氧基硼酸钠及氰基三(2,2,2三氟乙基)硼酸钠中的至少一种；
    可选地，所述硼酸类钠盐包括二氟草酸硼酸钠及二草酸硼酸钠中的至少一种。
  6. 根据权利要求1～5任一项所述的二次电池，其特征在于，所述电解质为电解液；
    可选地，所述电解质中的溶剂包括醚类溶剂。
  7. 根据权利要求6所述的二次电池，其特征在于，所述醚类溶剂包括乙二醇二甲醚、乙二醇二乙醚、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、四氢呋喃、甲基四氢呋喃、二苯醚及冠醚中的至少一种；
    可选地，所述醚类溶剂包括乙二醇二甲醚。
  8. 根据权利要求6或7所述的二次电池，其特征在于，在所述电解质中，所述硼酸类钠盐的摩尔浓度为0.05mol/L～8mol/L；
    可选地，所述硼酸类钠盐的摩尔浓度为0.1mol/L～2mol/L。
  9. 根据权利要求1～8任一项所述的二次电池，其特征在于，所述电解质还包括高氯酸钠、六氟磷酸钠、六氟砷酸钠、三氟乙酸钠、三氟甲基磺酸钠、双(氟磺酰)亚胺钠及双(三氟甲基磺酰)亚胺钠中的至少一种。
  10. 一种电池模块，其特征在于，包含如权利要求1～9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所述的电池模块。
  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1～9任一项所述的二次电池、如权利要求10所述的电池模块及如权利要求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。
PCT/CN2022/103814 2022-07-05 2022-07-05 二次电池、电池模块、电池包及用电装置 WO2024007143A1 (zh)

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CN106450247A (zh) * 2016-10-28 2017-02-22 南开大学 用于钠/钾离子二次电池的金属铋负极和醚基电解液
CN107768720A (zh) * 2016-08-18 2018-03-06 中国科学院物理研究所 基于液态电解液的无负极二次锂电池
CN112103512A (zh) * 2020-10-09 2020-12-18 中国科学院物理研究所 一种负极集流体、其制备方法与应用
CN113140723A (zh) * 2021-03-02 2021-07-20 复旦大学 一种基于金属铋负极的宽温钠离子电池
CN113437254A (zh) * 2021-06-26 2021-09-24 宁德时代新能源科技股份有限公司 钠离子电池的负极极片、电化学装置及电子设备
CN114373982A (zh) * 2021-12-30 2022-04-19 复旦大学 一种基于液态醚类有机电解液的少负极二次钠电池及其制备方法

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CN107768720A (zh) * 2016-08-18 2018-03-06 中国科学院物理研究所 基于液态电解液的无负极二次锂电池
CN106450247A (zh) * 2016-10-28 2017-02-22 南开大学 用于钠/钾离子二次电池的金属铋负极和醚基电解液
CN112103512A (zh) * 2020-10-09 2020-12-18 中国科学院物理研究所 一种负极集流体、其制备方法与应用
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