WO2024086987A1 - 混合添加剂、钠二次电池用电解液、钠二次电池、电池模块、电池包及用电装置 - Google Patents

混合添加剂、钠二次电池用电解液、钠二次电池、电池模块、电池包及用电装置 Download PDF

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WO2024086987A1
WO2024086987A1 PCT/CN2022/127115 CN2022127115W WO2024086987A1 WO 2024086987 A1 WO2024086987 A1 WO 2024086987A1 CN 2022127115 W CN2022127115 W CN 2022127115W WO 2024086987 A1 WO2024086987 A1 WO 2024086987A1
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sodium
ether
electrolyte
battery
secondary battery
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PCT/CN2022/127115
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English (en)
French (fr)
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秦猛
官英杰
杨惠玲
赵玉珍
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/CN2022/127115 priority Critical patent/WO2024086987A1/zh
Publication of WO2024086987A1 publication Critical patent/WO2024086987A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives

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  • the present application relates to the field of batteries, and in particular to a mixed additive, an electrolyte for a sodium secondary battery, a sodium secondary battery, a battery module, a battery pack, and an electrical device.
  • lithium secondary batteries can use the sodium ion deintercalation process between the positive and negative electrodes to achieve charging and discharging.
  • the reserves of sodium resources are far more abundant than lithium, the distribution is more extensive, and the cost is far lower than lithium. Therefore, sodium secondary batteries have become a new generation of electrochemical systems with great potential to replace lithium secondary batteries.
  • the electrolyte is continuously consumed as the battery is charged and discharged, which affects the cycle life of the battery.
  • the present application provides a mixed additive, aiming to alleviate the problem that the electrolyte consumption during the use of the sodium secondary battery containing the mixed additive affects its cycle life.
  • the first aspect of the present application provides a mixed additive, including a film-forming agent and a fluorine-containing sodium borate, wherein the film-forming agent includes a fluoroester and/or a fluoroether, wherein the mass ratio of the film-forming agent to the fluorine-containing sodium borate is (5-20): (0.5-2).
  • the present application at least includes the following beneficial effects: by mixing a film-forming agent including fluoroester and/or fluoroether with sodium borate containing fluorine as a mixed additive, and controlling the mass ratio of the film-forming agent to the sodium borate containing fluorine to be (5-20): (0.5-2), the mixed additive of this composition is added to the electrolyte for sodium secondary batteries, which can promote the formation of a NaF-rich SEI layer on the surface of the negative electrode of the battery. Due to its high interfacial energy and mechanical stability, NaF can effectively inhibit the growth of sodium dendrites and promote the uniform deposition of sodium ions on the surface of the negative electrode, thereby improving the cycle life of the battery.
  • the sodium borate containing fluorine in the mixed additive can form a stable CEI layer on the surface of the positive electrode, thereby alleviating the structural degradation of the positive electrode material. Further, the sodium borate containing fluorine in the mixed additive will not be hydrolyzed in the electrolyte to produce hydrogen fluoride, thereby reducing battery bulging.
  • the mixed additive in which the film-forming agent including fluoroester and/or fluoroether coexists with sodium borate containing fluorine can reduce the consumption of electrolyte sodium salt in the electrolyte while reducing their respective consumption, further improving the cycle life of the battery.
  • the molecular weight of the fluorinated ester is not greater than 800.
  • the cycle life of the battery can be further improved.
  • the number of carbon atoms in the main chain of the fluoroester is no more than 10.
  • the dispersibility of the fluoroester in the electrolyte can be improved, further improving the cycle life of the battery.
  • the viscosity of the fluoroester at 25° C. is not higher than 5 mPa ⁇ S.
  • the cycle life of the battery can be further improved.
  • the fluorinated ester includes fluoroethylene carbonate, trifluoroethyl methyl carbonate, difluoroethylene carbonate, bisfluoropropylene carbonate, trifluoroethyl acetate, trifluoromethylethylene carbonate, 4-trifluoromethylethylene carbonate, di(2,2,2-trifluoroethyl) carbonate, methyl trifluoropropionate, 3,3,3-trifluoroethyl acetate, methyl 2-trifluoromethylbenzoate, ethyl 4,4,4-trifluorobutyrate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, propyl fluorobutyrate, propyl fluoroacetate, isopropyl fluoroacetate, butyl fluoropropionate, isopropyl fluoropropionate, ethyl fluorobutyrate, methyl fluoropropionate, ethyl fluor
  • the molecular weight of the fluoroether is not greater than 800.
  • the cycle life of the battery can be further improved.
  • the number of carbon atoms in the main chain of the fluoroether is no more than 10.
  • the dispersibility of the fluoroether in the electrolyte can be improved, and the cycle life of the battery can be further improved.
  • the viscosity of the fluoroether at 25° C. is not higher than 2 mPa ⁇ S.
  • the cycle life of the battery can be further improved.
  • the fluorinated ether includes 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, bis(2,2,2-trifluoroethyl) ether, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, 2,2,2-trifluoroethyl methyl ether, 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 2,2,2-trifluoroethyl vinyl ether, polyperfluoromethyl isopropyl ether, 2,2,3,3,3-pentafluoropropyl-1,1,2,2-tetrafluoroethyl ether, diflu
  • the fluorine-containing sodium borate includes at least one of sodium tetrafluoroborate, sodium difluorooxalatoborate, sodium tetrakis(trifluoromethyl)borate, sodium bis(trifluoromethyl)difluoroborate, sodium pentafluoroethyl trifluoroborate, and sodium cyanotri(2,2,2 trifluoroethyl)borate.
  • the fluorine-containing sodium borate is of the given type, the cycle life of the battery can be further improved.
  • the film-forming agent includes a fluoroester and a fluoroether, and the mass ratio of the fluoroester to the fluoroether is (0.05-0.95): (0.05-0.95).
  • the mass ratio of the fluoroester to the fluoroether is within the given range, the cycle life of the battery can be further improved.
  • the second aspect of the present application provides an electrolyte for a sodium secondary battery, which includes an electrolyte sodium salt, an organic solvent and an additive, wherein the additive includes the mixed additive of the first aspect of the present application.
  • the electrolyte comprising the mixed additives of the above composition, electrolyte sodium salt and organic solvent is added to the sodium secondary battery as the electrolyte.
  • the mixed additives can promote the formation of a NaF-rich SEI layer on the surface of the negative electrode of the battery. Due to its high interfacial energy and mechanical stability, NaF can effectively inhibit the growth of sodium dendrites and promote the uniform deposition of sodium ions on the negative electrode surface, thereby improving the cycle life of the battery.
  • the fluorine-containing sodium borate in the mixed additive can form a stable CEI layer on the positive electrode surface, thereby alleviating the structural degradation of the positive electrode material.
  • the fluorine-containing sodium borate in the mixed additive will not be hydrolyzed in the electrolyte to produce hydrogen fluoride, thereby reducing battery bulging.
  • the mixed additive in which the film-forming agent including fluoroesters and/or fluoroethers coexists with the fluorine-containing sodium borate can reduce the consumption of electrolyte sodium salt in the electrolyte while reducing their respective consumption, further improving the cycle life of the battery.
  • the concentration of the fluorinated sodium borate in the mixed additive is 0.5 wt % to 2 wt %.
  • concentration of the fluorinated sodium borate in the mixed additive is within the given range, the structural degradation of the positive electrode material can be alleviated while reducing the internal resistance of the battery.
  • the concentration of the film former in the electrolyte is 5wt% to 20wt%.
  • the concentration of the film former is within the given range, it can not only reduce the consumption of each component in the mixed additive, but also reduce the consumption of electrolyte sodium salt in the electrolyte, further improving the cycle life of the battery.
  • the concentration of the electrolyte sodium salt in the electrolyte is 0.5 mol/L to 8 mol/L.
  • concentration of the electrolyte sodium salt is within the given range, the kinetic performance of the battery can be improved.
  • the electrolyte sodium salt includes at least one of sodium hexafluorophosphate, sodium difluorooxalatoborate, sodium tetrafluoroborate, sodium bisoxalatoborate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethylsulfonate, and sodium bis(trifluoromethylsulfonyl)imide.
  • the electrolyte sodium salt adopts the given type, the cycle life of the battery can be further improved.
  • the organic solvent includes at least one of an ester solvent, a sulfone solvent, an ether solvent, and a nitrile solvent.
  • the ether solvent includes at least one of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.
  • the ether solvent adopts the given type, the internal resistance of the battery can be reduced, thereby improving the dynamic performance of the battery.
  • the viscosity of the electrolyte at 25° C. is not higher than 8 mPa ⁇ S.
  • the cycle life of the battery can be further improved.
  • the ionic conductivity of the electrolyte is 0.5 mS/cm-20 mS/cm at 25° C.
  • the cycle life of the battery can be further improved.
  • the third aspect of the present application provides a sodium secondary battery, which includes a positive electrode plate, a negative electrode plate and an electrolyte, wherein the electrolyte includes the mixed additive of the first aspect of the present application or the electrolyte is the electrolyte for the sodium secondary battery of the second aspect of the present application.
  • the positive electrode active material in the positive electrode plate includes at least one of a layered transition metal oxide, a polyanion compound, and a Prussian blue analog.
  • the cycle life of the battery can be further improved.
  • the negative electrode active material in the negative electrode plate includes at least one of sodium metal, carbon material, alloy material, transition metal oxide and/or sulfide, phosphorus-based material, and titanate material.
  • the cycle life of the battery can be further improved.
  • a fourth aspect of the present application provides a battery module, which includes the sodium secondary battery according to the third aspect of the present application.
  • a fifth aspect of the present application provides a battery pack comprising at least one of the sodium secondary battery and the battery module of the above embodiment.
  • a sixth aspect of the present application provides an electrical device comprising at least one of the sodium secondary battery, battery module and battery pack of the above-mentioned embodiment.
  • FIG. 1 is a schematic structural diagram of a sodium secondary battery according to an embodiment of the present application.
  • FIG. 2 is a schematic structural diagram of a battery module according to an embodiment of the present application.
  • FIG. 3 is a schematic structural diagram of a battery pack according to an embodiment of the present application.
  • FIG. 4 is an exploded view of FIG. 3 .
  • FIG. 5 is a schematic diagram of an embodiment of an electric device using a sodium secondary battery as a power source.
  • any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and any upper limit can be combined with any other upper limit to form an unspecified range.
  • each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.
  • the term "and/or" is only a description of the association relationship of associated objects, indicating that three relationships may exist.
  • a and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone.
  • the character "/" in this article generally indicates that the associated objects before and after are in an "or" relationship.
  • Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.
  • electrolyte additives are mostly used to improve the electrochemical performance of sodium ion batteries.
  • the additives form a layer of solid electrolyte membrane (Solid Electrolyte Interface, SEI) on the surface of the negative electrode during the first charging process.
  • the formed SEI membrane is unstable and some irreversible side reactions will occur, resulting in a certain amount of active Na + being consumed at the negative electrode, while the additives are continuously consumed, so that the electrolyte is continuously consumed, affecting the cycle performance of the battery.
  • the first aspect of the present application discloses a mixed additive, the mixed additive comprising a film-forming agent and a fluorine-containing sodium borate, the film-forming agent comprising a fluorinated ester and/or a fluorinated ether, wherein the mass ratio of the film-forming agent to the fluorine-containing sodium borate is (5-20): (0.5-2), for example, the mass ratio of the film-forming agent to the fluorine-containing sodium borate is (5.5-19.5): (0.5-2), (6-19): (0.5-2), (6.5-18): (0.5-2), (8-16.5): (0.5-2), (9.5-15.5): (0.5-2), (11-14): (0.5-2), (12-13 ): (0.5 ⁇ 2), (5 ⁇ 20): (0.5 ⁇ 1.5), (5 ⁇ 20): (0.8 ⁇ 1.2), (5 ⁇ 20): (1 ⁇ 1.1), (6 ⁇ 18.5): (0.6 ⁇ 2), (7.5 ⁇ 17): (0.6 ⁇ 1.8), (8 ⁇ 16): (0.8 ⁇ 1.6), (10 ⁇ 14.5): (1 ⁇ 1.5),
  • the inventors found that if the mixed mass ratio of the film-forming agent and the sodium fluoride borate is too high, that is, the content of the sodium fluoride borate is too low, then the mixed additive is added to the electrolyte of the sodium secondary battery, and a stable CEI layer cannot be formed on the positive electrode surface; if the mixed mass of the film-forming agent and the sodium fluoride borate is too low, that is, the amount of sodium fluoride borate added is too high, then the mixed additive is added to the electrolyte of the sodium secondary battery, resulting in excessive internal resistance of the sodium secondary battery, thereby affecting the kinetic performance of the sodium secondary battery.
  • Adding the mixed additive of the present application composition to the electrolyte of the sodium secondary battery can promote the formation of a NaF-rich SEI layer on the surface of the negative electrode of the battery. Due to its high interfacial energy and mechanical stability, NaF can effectively inhibit the growth of sodium dendrites and promote the uniform deposition of sodium ions on the negative electrode surface, thereby improving the cycle life of the battery.
  • the sodium fluoride borate in the mixed additive can form a stable CEI layer on the positive electrode surface, thereby alleviating the structural degradation of the positive electrode material. Furthermore, the sodium fluoride borate in the mixed additive will not be hydrolyzed in the electrolyte to produce hydrogen fluoride, thereby reducing battery bulging.
  • a mixed additive comprising a film-forming agent including a fluoroester and/or a fluoroether and a sodium fluoride-containing borate can reduce the consumption of the electrolyte sodium salt in the electrolyte while reducing the consumption of each of the two agents, thereby further improving the cycle life of the battery.
  • the inventors of the present application have found through in-depth research that when the mixed additive of the present application satisfies the above conditions and optionally satisfies one or more of the following conditions, the cycle performance of the sodium secondary battery can be further improved.
  • the molecular weight of the fluoroester is not higher than 800, for example, the molecular weight of the fluoroester is 110-800, 130-750, 165-700, 195-650, 215-600, 245-570, 265-520, 315-475, 345-425, 375-400.
  • the cycle life of the battery can be further improved.
  • the molecular weight of the fluoroester is higher than 800, it will increase the viscosity of the electrolyte, affect the transmission of sodium ions in the electrolyte, and then reduce the cycle performance of the sodium secondary battery.
  • the molecular weight of the fluoroester refers to the relative molecular mass.
  • the number of main chain carbon atoms on the fluoroester is not more than 10, for example, the number of main chain carbon atoms on the fluoroester is 2-9, 3-8, 4-7, 5-6.
  • the number of main chain carbon atoms of the fluoroester is within the given range, the dispersibility of the fluoroester in the electrolyte can be improved, thereby facilitating the formation of a NaF-rich SEI layer on the surface of the negative electrode of the sodium secondary battery, further improving the cycle life of the battery.
  • the number of main chain carbon atoms on the fluoroester is higher than 10, the viscosity of the electrolyte will increase, affecting the transmission of sodium ions in the electrolyte, thereby reducing the cycle performance of the sodium secondary battery.
  • the viscosity of the fluoroester at 25°C is not higher than 5mPa ⁇ S, for example, the viscosity is 1mPa ⁇ S-5mPa ⁇ S, 1.5mPa ⁇ S-4.5mPa ⁇ S, 2mPa ⁇ S-4mPa ⁇ S, 2.5mPa ⁇ S-4.5mPa ⁇ S, 3mPa ⁇ S-4mPa ⁇ S.
  • the viscosity of the fluoroester is within the given range, the cycle life of the battery can be further improved. If the viscosity of the fluoroester at 25°C is higher than 5mPa ⁇ S, it will inhibit the ionic conductivity of the electrolyte and affect the transmission of sodium ions in the electrolyte.
  • the fluoroester includes fluoroethylene carbonate, trifluoroethyl methyl carbonate, difluoroethylene carbonate, difluoropropylene carbonate, trifluoroethyl acetate, trifluoromethylethylene carbonate, 4-trifluoromethylethylene carbonate, di(2,2,2-trifluoroethyl) carbonate, methyl trifluoropropionate, 3,3,3-trifluoroethyl acetate, methyl 2-trifluoromethylbenzoate, ethyl 4,4,4-trifluorobutyrate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, propyl fluorobutyrate, propyl fluoroacetate, isopropyl fluoroacetate, butyl fluoropropionate, isopropyl fluoropropionate, ethyl fluorobutyrate, methyl fluoropropionate, ethyl fluoro
  • the molecular weight of the fluoroether is not higher than 800, for example, the molecular weight of the fluoroether is 40-700, 50-700, 65-600, 75-500, 85-400, 95-300, 110-200.
  • the cycle life of the battery can be further improved.
  • the molecular weight of the fluoroether is higher than 800, it will increase the viscosity of the electrolyte, affect the transmission of sodium ions in the electrolyte, and then reduce the cycle performance of the sodium secondary battery.
  • the molecular weight of the fluoroether refers to the relative molecular mass.
  • the main chain carbon atoms of the fluoroether are not more than 10, for example, the main chain carbon atoms of the fluoroether are 2-9, 3-8, 4-7, 5-6.
  • the main chain carbon atoms of the fluoroether are within this range, the dispersibility of the fluoroether in the electrolyte can be improved, further improving the cycle life of the battery. If the main chain carbon atoms of the fluoroether are too high, the viscosity of the electrolyte will increase, affecting the transmission of sodium ions in the electrolyte, thereby reducing the cycle performance of the sodium secondary battery.
  • the viscosity of the fluoroether at 25°C is not higher than 2mPa ⁇ S, for example, the viscosity is 1mPa ⁇ S-2mPa ⁇ S, 1.2mPa ⁇ S-1.8mPa ⁇ S, 1.4mPa ⁇ S-1.6mPa ⁇ S, 1.4mPa ⁇ S-1.5mPa ⁇ S.
  • the viscosity of the fluoroether is within the given range, the cycle life of the battery can be further improved. If the viscosity of the fluoroether at 25°C is higher than 2mPa ⁇ S, it will inhibit the ionic conductivity of the electrolyte and affect the transmission of sodium ions in the electrolyte.
  • the fluorinated ether includes 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, bis(2,2,2-trifluoroethyl) ether, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, 2,2,2-trifluoroethyl methyl ether, 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, 2,2,2-trifluoroethyl vinyl ether, polyperfluoromethyl isopropyl ether, 2,2,3,3,3-pentafluoropropyl-1,1,2,2-tetrafluoroethyl ether, diflu
  • the viscosity test method of fluoroester and fluoroether at 25° C. refers to GB/T10247-2008.
  • the fluorine-containing sodium borate includes at least one of sodium tetrafluoroborate, sodium difluorooxalatoborate, sodium tetrakis(trifluoromethyl)borate, sodium bis(trifluoromethyl)difluoroborate, sodium pentafluoroethyl trifluoroborate, and sodium cyanotri(2,2,2 trifluoroethyl)borate.
  • the fluorine-containing sodium borate is stable in the electrolyte and will not hydrolyze to produce hydrogen fluoride, thereby reducing battery bulging.
  • the fluorine-containing sodium borate can form a stable CEI layer on the surface of the positive electrode, thereby alleviating the structural degradation of the positive electrode material.
  • the cycle life of the battery can be further improved.
  • the film-forming agent includes a fluoroester and a fluoroether
  • the mass ratio of the fluoroester to the fluoroether is (0.05-0.95):(0.05-0.95)
  • the mass ratio of the fluoroester to the fluoroether is (0.1-0.8):(0.05-0.95), (0.2-0.6):(0.05-0.95), (0.4-0.5):(0.05-0.95), (0 .05-0.95):(0.1-0.8), (0.05-0.95):(0.2-0.6), (0.05-0.95):(0.4-0.5), (0.1-0.8):(0.1-0.8), (0.2-0.7):(0.2-0.7), (0.3-0.6):(0.3-0.6), (0.4-0.5):(0.4-0.5).
  • the mass ratio of fluoroester to fluoroether is within the given range, the cycle life of the battery can be further improved.
  • the second aspect of the present application also provides an electrolyte for a sodium secondary battery, which includes an electrolyte sodium salt, an organic solvent and an additive, wherein the additive includes the mixed additive of the first aspect of the present application.
  • the inventor unexpectedly discovered that by adding an electrolyte comprising a mixed additive of the first aspect of the present application, an electrolyte sodium salt and an organic solvent to a sodium secondary battery as an electrolyte, the mixed additive can promote the formation of a NaF-rich SEI layer on the surface of the negative electrode of the battery. Due to its high interfacial energy and mechanical stability, NaF can effectively inhibit the growth of sodium dendrites and promote the uniform deposition of sodium ions on the negative electrode surface, thereby improving the cycle life of the battery. At the same time, the fluorine-containing sodium borate in the mixed additive can form a stable CEI layer on the positive electrode surface, thereby alleviating the structural degradation of the positive electrode material.
  • a mixed additive comprising a film-forming agent of a fluoroester and/or a fluoroether and coexisting with the fluorine-containing sodium borate can reduce the consumption of the electrolyte sodium salt in the electrolyte while reducing their respective consumption, further improving the cycle life of the battery.
  • the concentration of the sodium fluoride borate in the mixed additive is 0.5wt% to 2wt%, for example, 0.6wt% to 1.9wt%, 0.7wt% to 1.8wt%, 0.8wt% to 1.8wt%, 0.9wt% to 1.7wt%, 1wt% to 1.6wt%, 1.1wt% to 1.5wt%, 1.2wt% to 1.4wt%, 1.3wt% to 1.4wt%.
  • concentration of the sodium fluoride borate in the mixed additive is within the given range, the structural degradation of the positive electrode material can be alleviated while reducing the internal resistance of the battery.
  • the concentration of the sodium fluoride borate in the mixed additive is too low, a stable CEI layer cannot be formed on the surface of the positive electrode; if the concentration of the sodium fluoride borate is too high, the internal resistance of the sodium secondary battery will be too high, thereby affecting the kinetic performance of the sodium secondary battery.
  • the concentration of the film former in the electrolyte is 5wt% to 20wt%, such as 5wt% to 19wt%, 7wt% to 18wt%, 8wt% to 18wt%, 9wt% to 17wt%, 10wt% to 16wt%, 11wt% to 15wt%, 12wt% to 14wt%, 13wt% to 14wt%.
  • concentration of the film former is within the given range, it can not only reduce the consumption of each component in the mixed additive, but also reduce the consumption of electrolyte sodium salt in the electrolyte, further improving the cycle life of the battery.
  • the concentration of the electrolyte sodium salt in the electrolyte is 0.5 mol/L to 8 mol/L, for example, 1 mol/L to 7.5 mol/L, 1.5 mol/L to 8 mol/L, 2 mol/L to 7 mol/L, 2.5 mol/L to 6.5 mol/L, 3 mol/L to 6 mol/L, 3.5 mol/L to 5 mol/L, 4 mol/L to 4.5 mol/L.
  • concentration of the electrolyte sodium salt is within the given range, the kinetic performance of the battery can be improved.
  • the electrolyte sodium salt includes at least one of sodium hexafluorophosphate, sodium difluorooxalatoborate, sodium tetrafluoroborate, sodium bisoxalatoborate, sodium perchlorate, sodium hexafluoroarsenate, sodium bis(fluorosulfonyl)imide, sodium trifluoromethylsulfonate, and sodium bis(trifluoromethylsulfonyl)imide.
  • the electrolyte sodium salt adopts the given type, the cycle life of the battery can be further improved.
  • the organic solvent includes at least one of an ester solvent, a sulfone solvent, an ether solvent, and a nitrile solvent.
  • the ester solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl methanesulfonate, dimethyl sulfite, and diethyl sulfite.
  • the nitrile solvent includes at least one of acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, 3-methoxypropionitrile and cyclopentanenitrile.
  • the sulfone solvent includes at least one of dimethyl sulfoxide, sulfolane, diphenyl sulfoxide, thionyl chloride and dipropyl sulfone.
  • the ether solvent includes at least one of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.
  • the viscosity of ether solvents is smaller than that of other types of solvents.
  • the viscosity of the electrolyte at 25°C is not higher than 8mPa ⁇ S, for example, 1mPa ⁇ S-8mPa ⁇ S, 2mPa ⁇ S-7mPa ⁇ S, 3mPa ⁇ S-6mPa ⁇ S, 4mPa ⁇ S-5mPa ⁇ S.
  • the viscosity of the electrolyte is within the given range, the cycle performance of the battery can be further improved.
  • the viscosity of the electrolyte is too high, it affects the transmission of sodium ions in the electrolyte, thereby reducing the cycle performance of the sodium secondary battery.
  • the viscosity test method of the electrolyte at 25° C. refers to GB/T10247-2008.
  • the ionic conductivity of the electrolyte at 25° C. is 0.5 mS/cm-20 mS/cm, for example 1 mS/cm-19 mS/cm, 2 mS/cm-18 mS/cm, 4 mS/cm-16 mS/cm, 6 mS/cm-14 mS/cm, 8 mS/cm-12 mS/cm, 10 mS/cm-11 mS/cm.
  • the cycle life of the battery can be further improved.
  • the ionic conductivity of the electrolyte is too high (higher than 20 mS/cm), it is easier to form dendrites on the surface of the negative electrode when overcharging and charging in low temperature environments, which is prone to safety hazards.
  • the ionic conductivity of the electrolyte at 25°C is measured by a liquid conductivity tester.
  • a constant amplitude voltage signal is added between the two electrodes, and a certain current flows through the electrodes.
  • the magnitude of the current depends on the number of ions contained in the solution, and the conductivity of the measured medium is proportional to the output voltage of the operational amplifier.
  • the components and concentrations of the solutes contained in the detected liquid can be determined by measuring the conductivity of the liquid, i.e., the conductivity.
  • a conductivity meter is used to determine the components contained in the solution. Under the known premise, the conductivity is different due to the different ratios of only one component, so the concentration of the component contained in the solution can be measured.
  • the material types of fluoroesters, fluoroethers, sodium fluoride-containing borates, organic solvents, and electrolyte sodium salts can be tested using equipment and methods known in the art.
  • the infrared spectrum of the material can be tested to determine the characteristic peaks contained therein, thereby determining the material type.
  • fluoroesters, fluoroethers, sodium fluoride-containing borates, organic solvents, and electrolyte sodium salts can be subjected to infrared spectroscopy analysis using instruments and methods known in the art, such as an infrared spectrometer, such as the IS10 Fourier transform infrared spectrometer of Nicolet, USA, and tested according to the general rules of infrared spectroscopy analysis method of GB/T6040-2002.
  • infrared spectrometer such as the IS10 Fourier transform infrared spectrometer of Nicolet, USA
  • the third aspect of the present application discloses a sodium secondary battery, which includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, wherein the electrolyte includes the mixed additive described in the first aspect of the present application or the electrolyte is the electrolyte for the sodium secondary battery described in the second aspect of the present application.
  • the positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer disposed on the positive electrode current collector, wherein the positive electrode film layer includes a positive electrode active material.
  • the positive electrode current collector may be a conventional metal foil or a composite current collector (a metal material may be disposed on a polymer substrate to form a composite current collector).
  • the positive electrode current collector may be one or more of copper foil, aluminum foil, nickel foil, stainless steel foil, stainless steel mesh, and carbon-coated aluminum foil.
  • the specific type of the positive electrode active material is not limited, and any active material known in the art that can be used for the positive electrode of a secondary battery can be used, and those skilled in the art can select it according to actual needs.
  • the positive electrode active material may include, but is not limited to, at least one of a layered transition metal oxide, a polyanion compound, and a Prussian blue analog.
  • layered transition metal oxides examples include:
  • M 2 is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn and Ba, 0 ⁇ z ⁇ 0.1;
  • polyanionic compound examples include:
  • a 1 f M 3 g (PO 4 ) i O j X 1 3-j wherein A is one or more of H, Li, Na, K and NH 4 , M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu and Zn , X 1 is one or more of F, Cl and Br , 0 ⁇ f ⁇ 4, 0 ⁇ g ⁇ 2, 1 ⁇ i ⁇ 3, 0 ⁇ j ⁇ 2;
  • M 4 is one or more of Mn, Fe, Co, Ni, Cu and Zn
  • X 2 is one or more of F, Cl and Br, 0 ⁇ n ⁇ 2;
  • M 5 is one or more of Mn, Fe, Co, Ni, Cu and Zn, 0 ⁇ p ⁇ 2, 0 ⁇ q ⁇ 2;
  • Prussian blue analogs examples include:
  • A is one or more selected from H + , Li + , Na + , K + , NH4 + , Rb + , Cs + , Fr + , Be2+ , Mg2 + , Ca2 + , Sr2 + , Ba2+ and Ra2 + , and M6 and M7 are each independently selected from one or more selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn and W, which are cations of transition metal elements.
  • the positive electrode active material layer may also optionally include a conductive agent and a binder.
  • the conductive agent is used to improve the conductivity of the positive electrode active material layer
  • the binder is used to firmly bind the positive electrode active material and the binder to the positive electrode current collector.
  • the present application does not specifically limit the types of the conductive agent and the binder, and they can be selected according to actual needs.
  • the conductive agent can be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers;
  • the binder can be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, carboxymethyl cellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA) and polyvinyl alcohol (PVA).
  • SBR styrene-butadiene rubber
  • CMC carboxymethyl cellulose
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • EVA ethylene-vinyl acetate copolymer
  • PVA polyvinyl alcohol
  • the negative electrode plate generally includes a negative electrode current collector and a negative electrode film layer disposed on the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector may be made of conventional metal foil, carbon-coated metal foil or porous metal plate, etc.
  • the negative electrode current collector may be made of copper foil.
  • the negative electrode active material is not limited, and active materials known in the art that can be used for the negative electrode of a sodium secondary battery can be used, and those skilled in the art can select according to actual needs.
  • the negative electrode active material can include but is not limited to one or more of sodium metal, carbon material, alloy material, transition metal oxide and/or sulfide, phosphorus-based material, and titanate material.
  • the carbon material can be selected from one or more of hard carbon, soft carbon, amorphous carbon, and nanostructured carbon materials;
  • the alloy material can be selected from one or more of Si, Ge, Sn, Pb, and Sb;
  • the general formula of the transition metal oxide and sulfide is M x N y , wherein M is one or more of Fe, Co, Ni, Cu, Mn, Sn, Mo, Sb, and V, and N is O or S;
  • the phosphorus-based material can be selected from one or more of red phosphorus, white phosphorus, and black phosphorus;
  • the titanate material can be selected from one or more of Na 2 Ti 3 O 7 , Na 2 Ti 6 O 13 , Na 4 Ti 5 O 12 , Li 4 Ti 5 O 12 , and NaTi 2 (PO 4 ) 3. All of these materials can be obtained through commercial channels.
  • the negative electrode film layer may also optionally include a binder and a conductive agent, wherein the conductive agent is used to improve the conductivity of the negative electrode active material layer, and the binder is used to firmly bond the negative electrode active material and the binder to the negative electrode current collector.
  • the present application does not specifically limit the types of the conductive agent and the binder, and they can be selected according to actual needs.
  • the conductive agent can be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the binder can be one or more of styrene butadiene rubber (SBR), styrene butadiene rubber (SBCs), water-based acrylic resin and carboxymethyl cellulose (CMC).
  • SBR styrene butadiene rubber
  • SBCs styrene butadiene rubber
  • CMC carboxymethyl cellulose
  • the negative electrode active material layer may also optionally include a thickener, such as carboxymethyl cellulose (CMC).
  • a thickener such as carboxymethyl cellulose (CMC).
  • CMC carboxymethyl cellulose
  • the present application is not limited thereto, and the present application may also use other materials that can be used as thickeners for negative electrode sheets of sodium ion batteries.
  • the present application has no special restrictions, and any known porous structure isolation membrane with electrochemical stability and mechanical stability can be selected according to actual needs.
  • it can be a single-layer or multi-layer film containing one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • FIG1 is a secondary battery 1 with a square structure as an example.
  • the secondary battery may include an outer package for packaging the positive electrode sheet, the negative electrode sheet, and the electrolyte.
  • the outer package may include a shell and a cover plate.
  • the shell may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the shell has an opening connected to the receiving cavity, and the cover plate can be covered on the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the separator can be wound or laminated to form an electrode assembly.
  • the electrode assembly is encapsulated in the housing cavity.
  • the electrolyte can be an electrolyte, and the electrolyte is infiltrated in the electrode assembly.
  • the number of electrode assemblies contained in the sodium secondary battery can be one or more, which can be adjusted according to demand.
  • the outer package of the sodium secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.
  • the outer packaging of the sodium secondary battery may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PBS polybutylene succinate
  • the sodium secondary batteries may be assembled into a battery module.
  • the battery module may contain a plurality of sodium secondary batteries, and the specific number may be adjusted according to the application and capacity of the battery module.
  • FIG2 is a battery module 2 as an example.
  • a plurality of sodium secondary batteries 1 may be arranged in sequence along the length direction of the battery module 2. Of course, they may also be arranged in any other manner. Further, the plurality of sodium secondary batteries 1 may be fixed by fasteners.
  • the battery module 2 may further include a housing having a housing space, in which a plurality of sodium secondary batteries 1 are housed.
  • the battery modules may be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.
  • the battery pack 3 may include a battery box and a plurality of battery modules 2 disposed in the battery box.
  • the battery box includes an upper box body 4 and a lower box body 5, and the upper box body 4 can be covered on the lower box body 5 to form a closed space for accommodating the battery modules 2.
  • the plurality of battery modules 2 can be arranged in the battery box in any manner.
  • the present application also provides an electric device, which includes at least one of the sodium secondary battery, battery module and battery pack.
  • the sodium secondary battery, battery module or battery pack can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device.
  • the electric device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck), an electric train, a ship and a satellite, and an energy storage system.
  • the electrical device may select a sodium secondary battery, a battery module or a battery pack according to its usage requirements.
  • FIG5 is an example of an electric device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module may be used.
  • the electric device may be a mobile phone, a tablet computer, or a notebook computer.
  • the electric device is usually required to be thin and light, and a sodium secondary battery may be used as a power source.
  • mixed additive 1 Fluorinated ethylene carbonate and sodium difluorooxalatoborate (NaDFOB) were uniformly mixed at a mass ratio of 10:1 to obtain mixed additive 1, wherein the molecular weight of fluoroethylene carbonate was 106.05, the viscosity at 25° C. was 3.2 mPa ⁇ S, and the number of main chain carbon atoms was 3.
  • the composition of mixed additive 2-59 is shown in Table 1.
  • electrolyte sodium salt sodium bis(trifluoromethylsulfonyl)imide NaTFSI and mixed additive 1 were dissolved in organic solvent ethylene glycol dimethyl ether DME and stirred evenly to obtain electrolyte 1 with an electrolyte sodium salt concentration of 1 mol/L.
  • the compositions of electrolytes 2-63 are shown in Table 2.
  • the polyvinylidene fluoride binder is fully dissolved in N-methylpyrrolidone, and then a carbon black conductive agent and a positive electrode active material Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 are added to prepare a uniformly dispersed positive electrode slurry (the mass ratio of polyvinylidene fluoride, carbon black conductive agent and positive electrode active material Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 is 10:10:80).
  • the positive electrode slurry is evenly coated on both surfaces of the aluminum foil, and then transferred to a vacuum drying oven for complete drying. The obtained electrode sheet is roll-pressed and finally punched to obtain a positive electrode sheet.
  • the negative electrode active material hard carbon, the conductive carbon nanotube material and the binder sodium carboxymethyl cellulose are added to water and stirred into a uniform negative electrode slurry (the mass ratio of the negative electrode active material hard carbon to the conductive carbon nanotube and the binder sodium carboxymethyl cellulose is 94.4:4:1.6), the negative electrode slurry is coated on the surface of the negative electrode current collector copper foil, and then transferred to a vacuum drying oven for complete drying, and finally punched to obtain the negative electrode sheet.
  • the electrolyte used is the electrolyte 1-63 shown in Table 2 above.
  • Polypropylene film is used as the isolation film.
  • the positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is placed between the positive and negative electrode sheets to play an isolating role, and then they are wound to obtain an electrode assembly; the electrode assembly is placed in an outer package, and the prepared electrolyte is injected into the dried secondary battery. After vacuum packaging, standing, formation, and shaping processes, a secondary battery is obtained.
  • the electrolytes of the sodium secondary batteries of Examples 1-48 respectively adopt electrolytes 1-48 in Table 2; the sodium secondary batteries of Comparative Examples 1-15 adopt electrolytes 49-63 in Table 2.
  • Example 1 the prepared sodium secondary battery was charged to 4.15V at a constant current of 1/3C at 25°C, and then charged at a constant voltage of 4.15V until the current dropped to 0.05C to obtain the first charging capacity ( Cc1 ); then discharged to 2.5V at a constant current of 1/3C to obtain the first discharge capacity ( Cd1 ), and the coulombic efficiency of the sodium secondary battery was calculated according to the following formula.
  • Example 1 the sodium secondary battery is charged to 4.15V at a constant current of 1C at 25°C, then charged at a constant voltage of 4.15V until the current drops to 0.05C, and then discharged to 2.5V at a constant current of 1C to obtain the first cycle discharge capacity ( Cd1 ); the charging and discharging is repeated to the nth cycle, and the discharge capacity of the sodium secondary battery after n cycles is obtained, which is recorded as Cdn , and the capacity retention rate of the sodium secondary battery is calculated according to the following formula:
  • Capacity retention rate discharge capacity after n cycles (C dn )/first cycle discharge capacity (C d1 ).
  • DC internal resistance refers to the resistance of the current in the battery cell. After the battery discharge process is completed, the battery voltage will rebound due to the existence of polarization.
  • DC impedance technology uses the difference between the voltage at the moment before the end of the discharge and the voltage after the discharge is stabilized during the intermittent discharge process to calculate the battery internal resistance.
  • Example 1 the sodium secondary battery is charged to 4.15V at a constant current of 1C at 25°C, then charged at a constant voltage of 4.15V until the current drops to 0.05C, and then discharged to 2.5V at a constant current of 1C, and then left for 5 minutes (stabilization time) to continue the next cycle.
  • the sodium secondary battery after 200 cycles was disassembled in an argon atmosphere glove box ( H2O ⁇ 0.1ppm, O2 ⁇ 0.1ppm), and the surface morphology of the negative electrode was visually observed to determine whether sodium dendrites were generated. If there were no white spots on the negative electrode, it was determined that there were no sodium dendrites; if there were sporadic white spots on the negative electrode, it was determined that the sodium dendrites were slight; if there were dense white spots on the negative electrode, it was determined that the sodium dendrites were severe.
  • Example 1 the electrolytes in the secondary batteries after 100 and 200 cycles were respectively taken, and the 19 F NMR spectrum was used to quantitatively analyze the changes in the components in the electrolyte during the battery cycle.
  • Residual amount of film-forming agent % the content of film-forming agent in the electrolyte after n cycles / the content of film-forming agent in the electrolyte before the cycle ⁇ 100%
  • Residual amount of sodium fluoride borate % content of sodium fluoride borate in electrolyte after n cycles / content of sodium fluoride borate in electrolyte before cycle ⁇ 100%
  • Residual amount of electrolyte sodium salt (%) content of electrolyte sodium salt in the electrolyte after n cycles/content of electrolyte sodium salt in the electrolyte before cycles ⁇ 100%.
  • the sodium secondary battery obtained in Example 1-48 has higher coulombic efficiency and capacity retention rate and lower DCR, and no sodium dendrites are generated on the surface of the negative electrode plate of the sodium secondary battery obtained in Example 1-48 after 200 cycles, which shows that the mixed additive of the present application can improve the cycle life of the sodium secondary battery.

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Abstract

本申请公开了一种混合添加剂、钠二次电池用电解液、钠二次电池、电池模块、电池包及用电装置。混合添加剂包括：成膜剂和含氟硼酸钠，所述成膜剂包括氟代酯和/或氟代醚，其中，所述成膜剂与所述含氟硼酸钠的质量比为(5-20)：(0.5-2)。

Description

混合添加剂、钠二次电池用电解液、钠二次电池、电池模块、电池包及用电装置 技术领域
本申请涉及电池领域，具体涉及一种混合添加剂、钠二次电池用电解液、钠二次电池、电池模块、电池包及用电装置。
背景技术
锂资源的日益紧缺、上游材料价格不断攀升、循环回收技术开发滞后、老旧电池循环回收利用率低下等问题使得锂二次电池面临着极大的挑战。钠二次电池能够利用钠离子在正负极之间的脱嵌过程实现充放电，而且钠资源的储量远比锂丰富、分布更为广泛、成本远比锂低，因此钠二次电池成为很有潜能替代锂二次电池的新一代电化学体系。
钠二次电池在充放电的使用过程中，随着电池的充放电循环，电解液被不断消耗，影响电池的循环寿命。
发明内容
鉴于背景技术中存在的技术问题，本申请提供一种混合添加剂，旨在缓解含有其的钠二次电池使用过程中电解液消耗影响其循环寿命的问题。
为了实现上述目的，本申请的第一方面提供了一种混合添加剂，包括成膜剂和含氟硼酸钠，所述成膜剂包括氟代酯和/或氟代醚，其中，所述成膜剂与所述含氟硼酸钠的质量比为(5-20)：(0.5-2)。
相对于现有技术，本申请至少包括如下所述的有益效果：通过将包括氟代酯和/或氟代醚的成膜剂与含氟硼酸钠混合作为混合添加剂，且控制成膜剂与含氟硼酸钠的质量比为(5-20)：(0.5-2)，该组成的混合添加剂加入到钠二次电池用电解液中，可以促进在电池负极表面形成富含NaF的SEI层，NaF由于高的界面能和机械稳定性，可以有效抑制钠枝晶的生长且促进钠离子在负极表面均匀沉积，从而提升电池的循环寿命。同时混合添加剂中的含氟硼酸钠可以在正极表面形成稳定的CEI层，从而缓解正极材料的结构退化。进一步地，混合添加剂中的含氟硼酸钠在电解液中不会发生水解而产生氟化氢，从而降低电池鼓包。另外，包括氟代酯和/或氟代醚的成膜剂与含氟硼酸钠共存的混合添加剂可以在降低各自消耗的同时降低电解液中电解质钠盐的消耗，进一步提升电池的循环寿命。
在一些实施例中，所述氟代酯的分子量不高于800。当氟代酯的分子量在所给范围内时，可以进一步提升电池的循环寿命。
在一些实施例中，所述氟代酯上主链碳原子数不大于10。当氟代酯的主链碳原子数在所给范围内时，可以提高氟代酯在电解液中的分散性，进一步提升电池的循环寿命。
在一些实施例中，所述氟代酯在25℃的粘度不高于5mPa·S。当该氟代酯的粘度在所给范围内时，可以进一步提升电池的循环寿命。
在一些实施例中，所述氟代酯包括氟代碳酸乙烯酯、三氟乙基甲基碳酸酯、二氟代碳酸乙烯酯、双 氟碳酸丙烯酯、三氟代乙酸乙酯、三氟甲基碳酸乙烯酯、4-三氟代甲基碳酸乙烯酯、二(2,2,2-三氟乙基)碳酸酯、三氟丙酸甲酯、3,3,3-三氟代乙酸乙酯、2-三氟甲基苯甲酸甲酯、4,4,4-三氟丁酸乙酯、1,1,1,3,3,3-六氟异丙基丙烯酸酯、氟代丁酸丙酯、氟代乙酸丙酯、氟代乙酸异丙酯、氟代丙酸丁酯、氟代丙酸异丙酯、氟代丁酸乙酯，氟代丙酸甲酯、氟代丙酸乙酯和氟代丙酸丙酯中的至少之一。当氟代酯采用所给类型时，可以进一步提升电池的循环寿命。
在一些实施例中，所述氟代醚的分子量不高于800。当氟代醚的分子量在所给范围内，可以进一步提升电池的循环寿命。
在一些实施例中，所述氟代醚上主链碳原子数不大于10。当氟代醚的主链碳原子数在所给范围内，可以提高氟代醚在电解液中的分散性，可以进一步提升电池的循环寿命。
在一些实施例中，所述氟代醚在25℃的粘度不高于2mPa·S。当该氟代醚的粘度在所给范围内，可以进一步提升电池的循环寿命。
在一些实施例中，所述氟代醚包括1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚、双(2,2,2-三氟乙基)醚、甲基九氟丁醚、乙基九氟丁基醚、2,2,2-三氟乙基甲基醚、1,1,1,3,3,3-六氟-2-(氟甲氧基)丙烷、1,1,2,2-四氟乙基-2,2,2-三氟乙醚、2,2,2-三氟乙基乙烯基醚、聚全氟甲基异丙基醚、2,2,3,3,3-五氟丙基-1,1,2,2-四氟乙醚、二氟甲基-2,2,3,3-四氟丙基醚、2,2,3,3-四氟-1-甲氧基丙烷、1,1,2,2-四氟乙基乙醚、1,1,2,3,3,3-六氟丙基甲醚、乙基全氟丁基醚、七氟丙基-1,2,2,2-四氟乙醚、1,1,2,3,3,3-五氟丙基-2,2,2-三氟乙醚、2,2,3,3,3-五氟丙基二氟甲醚、2-全氟丙氧基全氟丙基三氟乙烯基醚、2,3,3,3-四氟-2-(七氟丙氧基)丙酰氟化物、烯丙基-2,2,3,3-四氟丙醚、烯丙基-1,1,2,2-四氟乙基醚、叔丁基-1,1,2,2-四氟乙基醚和2,2,2-三氟乙基乙基醚中的至少之一。当氟代醚采用所给类型时，可以进一步提升电池的循环寿命。
在一些实施例中，所述含氟硼酸钠包括四氟硼酸钠、二氟草酸硼酸钠、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和氰基三(2,2,2三氟乙基)硼酸钠中的至少之一。当含氟硼酸钠采用所给类型时，可以进一步提升电池的循环寿命。
在一些实施例中，所述成膜剂包括氟代酯和氟代醚，所述氟代酯和氟代醚的质量比为(0.05-0.95)：(0.05-0.95)。当氟代酯和氟代醚质量比在所给范围内时，可以进一步提升电池的循环寿命。
本申请第二方面提供了一种钠二次电池用电解液，其包括电解质钠盐、有机溶剂和添加剂，其中，所述添加剂包括本申请第一方面的混合添加剂。
将包括上述组成的混合添加剂与电解质钠盐和有机溶剂的电解液加入到钠二次电池中作为电解液，混合添加剂可以促进在电池负极表面形成富含NaF的SEI层，NaF由于高的界面能和机械稳定性，可以有效抑制钠枝晶的生长且促进钠离子在负极表面均匀沉积，从而提升电池的循环寿命。同时混合添加剂中的含氟硼酸钠可以在正极表面形成稳定的CEI层，从而缓解正极材料的结构退化。进一步地，混合添加剂中的含氟硼酸钠在电解液中不会发生水解而产生氟化氢，从而降低电池鼓包。另外，包括氟代酯和/或氟代醚的成膜剂与含氟硼酸钠共存的混合添加剂可以在降低各自消耗的同时降低电解液中电解质钠盐的消耗，进一步提升电池的循环寿命。
在一些实施例中，在所述电解液中，所述混合添加剂中的含氟硼酸钠的浓度为0.5wt％～2wt％。当混合添加剂中含氟硼酸钠浓度在所给范围内时，可以在降低电池内阻的同时缓解正极材料的结构退化。
在一些实施例中，所述电解液中成膜剂的浓度为5wt％～20wt％。当成膜剂的浓度在所给范围内时，不仅可以降低混合添加剂中各组分的消耗，而且可以降低电解液中电解质钠盐的消耗，进一步提升电池的循环寿命。
在一些实施例中，所述电解液中电解质钠盐的浓度为0.5mol/L～8mol/L。当电解质钠盐浓度在所给范围内时，可以提高电池的动力学性能。
在一些实施例中，所述电解质钠盐包括六氟磷酸钠、二氟草酸硼酸钠、四氟硼酸钠、双草酸硼酸钠、高氯酸钠、六氟砷酸钠、双(氟磺酰)亚胺钠、三氟甲基磺酸钠和双(三氟甲基磺酰)亚胺钠中的至少之一。当电解质钠盐采用所给类型时，可以进一步提升电池的循环寿命。
在一些实施例中，所述有机溶剂包括酯类溶剂、砜类溶剂、醚类溶剂和腈类溶剂中的至少之一。
在一些实施例中，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、二苯醚和冠醚中的至少之一。当醚类溶剂采用所给类型时，可以降低电池的内阻，进而提高电池的动力学性能。
在一些实施例中，所述电解液在25℃下的粘度不高于8mPa·S。当电解液的粘度在所给范围内时，可以进一步提升电池的循环寿命。
在一些实施例中，所述电解液在25℃下的离子电导率为0.5mS/cm-20mS/cm。当电解液的离子电导率在所给范围内时，可以进一步提升电池的循环寿命。
本申请第三方面提供了一种钠二次电池，其包括正极极片、负极极片和电解液，所述电解液包括本申请第一方面的混合添加剂或所述电解液为本申请第二方面的钠二次电池用电解液。
在一些实施例中，所述正极极片中正极活性材料包括层状过渡金属氧化物、聚阴离子化合物和普鲁士蓝类似物中的至少之一。当正极极片采用所给类型的正极活性材料时，可以进一步提升电池的循环寿命。
在一些实施例中，所述负极极片中负极活性材料包括钠金属、碳材料、合金材料、过渡金属氧化物和/或硫化物、磷基材料、钛酸盐材料中的至少之一。当负极极片采用所给类型的负极活性材料时，可以进一步提升电池的循环寿命。
本申请第四方面提供了一种电池模块，其包括上述本申请第三方面的钠二次电池。
本申请第五方面提供了一种电池包，其包括上述实施方式的钠二次电池和电池模块中的至少一种。
本申请第六方面提供了一种用电装置，其包括上述实施方式的钠二次电池、电池模块和电池包中的至少一种。
上述说明仅是本申请技术方案的概述，为了能够更清楚了解本申请的技术手段，而可依照说明书的内容予以实施，并且为了让本申请的上述和其它目的、特征和优点能够更明显易懂，以下特举本申请的具体实施方式。
附图说明
通过阅读对下文优选实施方式的详细描述，各种其他的优点和益处对于本领域普通技术人员将变得清楚明了。附图仅用于示出优选实施方式的目的，而并不认为是对本申请的限制。而且在全部附图中，用相同的附图标号表示相同的部件。在附图中：
图1是本申请一实施方式的钠二次电池的结构示意图。
图2是本申请一实施方式的电池模块的结构示意图。
图3是本申请一实施方式的电池包的结构示意图。
图4是图3的分解图。
图5是钠二次电池用作电源的用电装置的一实施方式的示意图。
附图标记说明：
1：二次电池；2：电池模块；3：电池包；4：上箱体；5：下箱体。
具体实施方式
下面对本申请技术方案的实施例进行详细的描述。以下实施例仅用于更加清楚地说明本申请的技术方案，因此只作为示例，而不能以此来限制本申请的保护范围。
在本文中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。本领域技术人员显式地和隐式地理解的是，本文所描述的实施例可以与其它实施例相结合。
为了简明，本文仅具体地公开了一些数值范围。然而，任意下限可以与任意上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，每个单独公开的点或单个数值自身可以作为下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本申请实施例的描述中，术语“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同；本文中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。
目前，从市场形势的发展来看，钠二次电池的应用越加广泛。动力电池不仅被应用于水力、火力、风力和太阳能电站等储能电源系统，而且还被广泛应用于电动自行车、电动摩托车、电动汽车等电动交通工具，以及军事装备和航空航天等多个领域。随着动力电池应用领域的不断扩大，其市场的需求量也在不断地扩增。
本申请发明人注意到，电解液作为钠离子二次电池的重要组成部分，不仅在电池正极与负极之间起到传递钠离子的作用，尤其还对电池的性能有着重要影响。目前多采用电解液添加剂来提高钠离子电池的电化学性能，添加剂在首次充电过程中在负极表面形成一层固体电解质膜(SolidElectrolyte Interface，SEI)，然而形成的SEI膜不稳定且会发生一些不可逆副反应，造成在负极消耗一定量的活性Na +，同时持续消耗添加剂，从而使得电解液被不断消耗，影响电池的循环性能。
于是，本申请第一方面公开了一种混合添加剂，所述混合添加剂包括成膜剂和含氟硼酸钠，成膜剂 包括氟代酯和/或氟代醚，其中，成膜剂与含氟硼酸钠的质量比为(5～20)：(0.5～2)，例如成膜剂与含氟硼酸钠的质量比为(5.5～19.5)：(0.5～2)，(6～19)：(0.5～2)，(6.5～18)：(0.5～2)，(8～16.5)：(0.5～2)，(9.5～15.5)：(0.5～2)，(11～14)：(0.5～2)，(12～13)：(0.5～2)，(5～20)：(0.5～1.5)，(5～20)：(0.8～1.2)，(5～20)：(1～1.1)，(6～18.5)：(0.6～2)，(7.5～17)：(0.6～1.8)，(8～16)：(0.8～1.6)，(10～14.5)：(1～1.5)，(11.5～13)：(1.1～1.4)，(12.5～13)：(1.2～1.3)。
发明人经大量研究发现，若成膜剂与含氟硼酸钠混合质量比例过高，即含氟硼酸钠含量过低，则将该混合添加剂加入到钠二次电池的电解液中，无法在正极表面形成稳定的CEI层；若成膜剂与含氟硼酸钠混合质量过低，即含氟硼酸钠加入量过高，则将该混合添加剂加入到钠二次电池的电解液中，导致钠二次电池内阻过高，从而影响钠二次电池的动力学性能。将本申请组成的混合添加剂加入到钠二次电池的电解液中，可以促进在电池负极表面形成富含NaF的SEI层，NaF由于高的界面能和机械稳定性，可以有效抑制钠枝晶的生长且促进钠离子在负极表面均匀沉积，从而提升电池的循环寿命。同时混合添加剂中的含氟硼酸钠可以在正极表面形成稳定的CEI层，从而缓解正极材料的结构退化。进一步地，混合添加剂中的含氟硼酸钠在电解液中不会发生水解而产生氟化氢，从而降低电池鼓包。另外，包括氟代酯和/或氟代醚的成膜剂与含氟硼酸钠共存的混合添加剂可以在降低各自消耗的同时降低电解液中电解质钠盐的消耗，进一步提升电池的循环寿命。
本申请发明人经深入研究发现，当本申请的混合添加剂在满足上述条件的基础上，若还可选地满足下述条件中的一个或几个时，可以进一步改善钠二次电池的循环性能。
在一些实施方式中，所述氟代酯的分子量不高于800，例如氟代酯的分子量为110-800，130-750，165-700，195-650，215-600，245-570，265-520，315-475，345-425，375-400。当氟代酯的分子量在所给范围内时，可以进一步提升电池的循环寿命。氟代酯的分子量如果高于800，会增加电解液粘度，影响钠离子在电解液中传输，进而降低钠二次电池的循环性能。具体的，所述氟代酯的分子量指相对分子质量。
在一些实施方式中，所述氟代酯上主链碳原子数不大于10，例如氟代酯上主链碳原子数为2-9，3-8，4-7，5-6。当氟代酯的主链碳原子数在所给范围内时，可以提高氟代酯在电解液中的分散性，从而利于在钠二次电池负极表面形成富含NaF的SEI层，进一步提升电池的循环寿命。氟代酯上主链碳原子数如果高于10，会增加电解液粘度，影响钠离子在电解液中传输，进而降低钠二次电池的循环性能。
在一些实施方式中，所述氟代酯在25℃的粘度不高于5mPa·S，例如粘度为1mPa·S-5mPa·S，1.5mPa·S-4.5mPa·S，2mPa·S-4mPa·S，2.5mPa·S-4.5mPa·S，3mPa·S-4mPa·S。当氟代酯的粘度在所给范围内时，可以进一步提升电池的循环寿命。氟代酯在25℃的粘度如果高于5mPa·S，会抑制电解液的离子电导率，影响钠离子在电解液中传输。
在一些实施方式中，所述氟代酯包括氟代碳酸乙烯酯、三氟乙基甲基碳酸酯、二氟代碳酸乙烯酯、双氟碳酸丙烯酯、三氟代乙酸乙酯、三氟甲基碳酸乙烯酯、4-三氟代甲基碳酸乙烯酯、二(2,2,2-三氟乙基)碳酸酯、三氟丙酸甲酯、3,3,3-三氟代乙酸乙酯、2-三氟甲基苯甲酸甲酯、4,4,4-三氟丁酸乙酯、1,1,1,3,3,3-六氟异丙基丙烯酸酯、氟代丁酸丙酯、氟代乙酸丙酯、氟代乙酸异丙酯、氟代丙酸丁酯、氟代丙酸异丙酯、氟代丁酸乙酯，氟代丙酸甲酯、氟代丙酸乙酯和氟代丙酸丙酯中的至少之一。当氟代酯采用所给类型时，可以进一步提升电池的循环寿命。
在一些实施方式中，所述氟代醚的分子量不高于800，例如氟代醚的分子量为40-700，50-700，65-600，75-500，85-400，95-300，110-200。当氟代醚的分子量在所给范围内，可以进一步提升电池的循环寿命。氟代醚的分子量如果高于800，会增加电解液粘度，影响钠离子在电解液中传输，进而降低钠二次电池的循环性能。具体的，所述氟代醚的分子量指相对分子质量。
在一些实施方式中，所述氟代醚上主链碳原子数不大于10，例如氟代醚上主链碳原子数为2-9，3-8，4-7，5-6。当氟代醚的主链碳原子数在该范围内，可以提高氟代醚在电解液中的分散性，进一步提升电池的循环寿命。氟代醚上主链碳原子数如果过高，会增加电解液粘度，影响钠离子在电解液中传输，进而降低钠二次电池的循环性能。
在一些实施方式中，所述氟代醚在25℃的粘度不高于2mPa·S，例如粘度为1mPa·S-2mPa·S，1.2mPa·S-1.8mPa·S，1.4mPa·S-1.6mPa·S，1.4mPa·S-1.5mPa·S。当氟代醚的粘度在所给范围内时，可以进一步提升电池的循环寿命。氟代醚在25℃的粘度如果高于2mPa·S，会抑制电解液的离子电导率，影响钠离子在电解液中传输。
在一些实施方式中，所述氟代醚包括1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚、双(2,2,2-三氟乙基)醚、甲基九氟丁醚、乙基九氟丁基醚、2,2,2-三氟乙基甲基醚、1,1,1,3,3,3-六氟-2-(氟甲氧基)丙烷、1,1,2,2-四氟乙基-2,2,2-三氟乙醚、2,2,2-三氟乙基乙烯基醚、聚全氟甲基异丙基醚、2,2,3,3,3-五氟丙基-1,1,2,2-四氟乙醚、二氟甲基-2,2,3,3-四氟丙基醚、2,2,3,3-四氟-1-甲氧基丙烷、1,1,2,2-四氟乙基乙醚、1,1,2,3,3,3-六氟丙基甲醚、乙基全氟丁基醚、七氟丙基-1,2,2,2-四氟乙醚、1,1,2,3,3,3-五氟丙基-2,2,2-三氟乙醚、2,2,3,3,3-五氟丙基二氟甲醚、2-全氟丙氧基全氟丙基三氟乙烯基醚、2,3,3,3-四氟-2-(七氟丙氧基)丙酰氟化物、烯丙基-2,2,3,3-四氟丙醚、烯丙基-1,1,2,2-四氟乙基醚、叔丁基-1,1,2,2-四氟乙基醚和2,2,2-三氟乙基乙基醚中的至少之一。当氟代醚采用所给类型时，可以进一步提升电池的循环寿命。
根据一些实施例，氟代酯和氟代醚在25℃的粘度测试方法参照GB/T10247-2008。
在一些实施方式中，所述含氟硼酸钠包括四氟硼酸钠、二氟草酸硼酸钠、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和氰基三(2,2,2三氟乙基)硼酸钠中的至少之一。含氟硼酸钠在电解液中性质稳定，不会发生水解而产生氟化氢，从而降低电池鼓包。同时含氟硼酸钠可以在正极表面形成稳定的CEI层，从而缓解正极材料的结构退化。当含氟硼酸钠采用所给类型时，可以进一步提升电池的循环寿命。
在一些实施方式中，所述成膜剂包括氟代酯和氟代醚，所述氟代酯和氟代醚的质量比为(0.05-0.95)：(0.05-0.95)，例如氟代酯和氟代醚的质量比为(0.1-0.8)：(0.05-0.95)，(0.2-0.6)：(0.05-0.95)，(0.4-0.5)：(0.05-0.95)，(0.05-0.95)：(0.1-0.8)，(0.05-0.95)：(0.2-0.6)，(0.05-0.95)：(0.4-0.5)，(0.1-0.8)：(0.1-0.8)，(0.2-0.7)：(0.2-0.7)，(0.3-0.6)：(0.3-0.6)，(0.4-0.5)：(0.4-0.5)。当氟代酯和氟代醚质量比在所给范围内时，可以进一步提升电池的循环寿命。
本申请第二方面还提供一种钠二次电池用电解液，其包括电解质钠盐、有机溶剂和添加剂，其中，所述添加剂包括本申请第一方面的混合添加剂。
发明人意外发现，将包括本申请第一方面的混合添加剂与电解质钠盐和有机溶剂的电解液加入到钠二次电池中作为电解液，混合添加剂可以促进在电池负极表面形成富含NaF的SEI层，NaF由于高的界 面能和机械稳定性，可以有效抑制钠枝晶的生长且促进钠离子在负极表面均匀沉积，从而提升电池的循环寿命。同时混合添加剂中的含氟硼酸钠可以在正极表面形成稳定的CEI层，从而缓解正极材料的结构退化。进一步地，混合添加剂中的含氟硼酸钠在电解液中不会发生水解而产生氟化氢，从而降低电池鼓包。另外，包括氟代酯和/或氟代醚的成膜剂与含氟硼酸钠共存的混合添加剂可以在降低各自消耗的同时降低电解液中电解质钠盐的消耗，进一步提升电池的循环寿命。
在一些实施方式中，在所述电解液中，所述混合添加剂中的含氟硼酸钠的浓度为0.5wt％～2wt％，例如0.6wt％～1.9wt％，0.7wt％～1.8wt％，0.8wt％～1.8wt％，0.9wt％～1.7wt％，1wt％～1.6wt％，1.1wt％～1.5wt％，1.2wt％～1.4wt％，1.3wt％～1.4wt％。当混合添加剂中含氟硼酸钠浓度在所给范围内时，可以在降低电池内阻的同时缓解正极材料的结构退化。混合添加剂中含氟硼酸钠浓度过低，则无法在正极表面形成稳定的CEI层；若含氟硼酸钠的浓度过高，则会导致钠二次电池内阻过高，从而影响钠二次电池的动力学性能。
在一些实施方式中，所述电解液中成膜剂的浓度为5wt％～20wt％，例如5wt％～19wt％，7wt％～18wt％，8wt％～18wt％，9wt％～17wt％，10wt％～16wt％，11wt％～15wt％，12wt％～14wt％，13wt％～14wt％。当成膜剂的浓度在所给范围内时，不仅可以降低混合添加剂中各组分的消耗，而且可以降低电解液中电解质钠盐的消耗，进一步提升电池的循环寿命。
在一些实施方式中，所述电解液中电解质钠盐的浓度为0.5mol/L～8mol/L，例如1mol/L～7.5mol/L，1.5mol/L～8mol/L，2mol/L～7mol/L，2.5mol/L～6.5mol/L，3mol/L～6mol/L，3.5mol/L～5mol/L，4mol/L～4.5mol/L。当电解质钠盐浓度在所给范围内时，可以提高电池的动力学性能。
在一些实施方式中，所述电解质钠盐包括六氟磷酸钠、二氟草酸硼酸钠、四氟硼酸钠、双草酸硼酸钠、高氯酸钠、六氟砷酸钠、双(氟磺酰)亚胺钠、三氟甲基磺酸钠和双(三氟甲基磺酰)亚胺钠中的至少之一。当电解质钠盐采用所给类型时，可以进一步提升电池的循环寿命。
在一些实施方式中，所述有机溶剂包括酯类溶剂、砜类溶剂、醚类溶剂和腈类溶剂中的至少之一。
在一些实施方式中，所述酯类溶剂包括碳酸乙烯酯、碳酸丙烯酯、碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、甲磺酸乙酯、亚硫酸二甲酯和亚硫酸二乙酯中的至少之一。
在一些实施方式中，所述腈类溶剂包括乙腈、丙腈、丁腈、异丁腈、戊腈、3-甲氧基丙腈和环戊烷腈中的至少之一。
在一些实施方式中，所述砜类溶剂包括二甲基亚砜、环丁砜、二苯基亚砜、氯化亚砜和二丙砜中的至少之一。
在一些实施方式中，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、二苯醚和冠醚中的至少之一。醚类溶剂粘度相对于其他类型溶剂粘度更小，采用醚类溶剂作为钠二次电池用电解液中有机溶剂，可以降低电池内阻。同时当醚类溶剂采用所给类型时，可以显著降低电池的内阻，进而提高电池的动力学性能。
在一些实施方式中，所述电解液在25℃下的粘度不高于8mPa·S，例如1mPa·S-8mPa·S，2mPa·S-7mPa·S，3mPa·S-6mPa·S，4mPa·S-5mPa·S。当电解液的粘度在所给范围内时，可以进一步提升电池的循环性能。当电解液的粘度过高，影响钠离子在电解液中传输，进而降低钠二次电池的循环性能。
根据一些实施例，电解液在25℃下的粘度测试方法参照GB/T10247-2008。
在一些实施方式中，所述电解液在25℃下的离子电导率为0.5mS/cm-20mS/cm，例如1mS/cm-19mS/cm，2mS/cm-18mS/cm，4mS/cm-16mS/cm，6mS/cm-14mS/cm，8mS/cm-12mS/cm，10mS/cm-11mS/cm。当电解液的离子电导率在所给范围内时，可以进一步提升电池的循环寿命。当电解液的离子电导率过高(高于20mS/cm)，过充和低温环境下充电更容易在负极表面形成枝晶，易发生安全隐患。
根据一些实施例，电解液在25℃下的离子电导率通过液体电导率测试仪测量。在电导率的测量过程中，两电极间加上恒定的振幅电压信号，电极上流经一定的电流，电流的大小，取决于溶液中所含离子的数量，被测介质的电导率与运算放大器的输出电压成正比。(测量原理：由于各种液体中的离子随所含成份和浓度的不同，其导电性能不同，从而可通过测量液体的导电性即电导率来判定所检测液体中所含的溶质的成份和浓度。通常用电导仪来判定溶液中所含成份，在已知的前提下只有一种成份所含比率不同所引起的电导率不同，从而测出溶液所含该成份的浓度。)
根据一些实施例，氟代酯、氟代醚、含氟硼酸钠、有机溶剂、电解质钠盐的物质种类可以采用本领域已知的设备和方法进行测试。例如，可以测试材料的红外光谱，确定其包含的特征峰，从而确定材料种类。具体地，可以用本领域公知的仪器及方法对氟代酯、氟代醚、含氟硼酸钠、有机溶剂、电解质钠盐进行红外光谱分析，例如红外光谱仪，如采用美国尼高力(Nicolet)公司的IS10型傅里叶变换红外光谱仪，依据GB/T6040-2002红外光谱分析方法通则测试。
本申请第三方面公开了一种钠二次电池，其包括正极极片、负极极片、隔离膜和电解液，所述电解液包括本申请第一方面所述的混合添加剂或所述电解液为本申请第二方面所述的钠二次电池用电解液。
[正极极片]
在钠二次电池中，所述正极极片通常包括正极集流体及设置在正极集流体上的正极膜层，所述正极膜层包括正极活性材料。
所述正极集流体可以采用常规金属箔片或复合集流体(可以将金属材料设置在高分子基材上形成复合集流体)。作为示例，正极集流体可以为铜箔、铝箔、镍箔、不锈钢箔、不锈钢网及涂炭铝箔中的一种或几种。
所述正极活性材料的具体种类不做限制，可以采用本领域已知的能够用于二次电池正极的活性材料，本领域技术人员可以根据实际需求进行选择。
作为示例，所述正极活性材料可以包括但不限于层状过渡金属氧化物、聚阴离子化合物和普鲁士蓝类似物中的至少之一。
作为上述层状过渡金属氧化物的示例，例如可以列举出：
Na 1-xCu hFe kMn lM 1 mO 2-y，其中M 1为Li、Be、B、Mg、Al、K、Ca、Ti、Co、Ni、Zn、Ga、Sr、Y、Nb、Mo、In、Sn及Ba中的一种或几种，0<x≤0.33，0<h≤0.24，0≤k≤0.32，0<l≤0.68，0≤m<0.1，h+k+l+m＝1，0≤y<0.2；
Na 0.67Mn 0.7Ni zM 2 0.3-zO 2，其中M 2为Li、Mg、Al、Ca、Ti、Fe、Cu、Zn及Ba中的一种或几种，0<z≤0.1；
Na aLi bNi cMn dFe eO 2，其中0.67<a≤1，0<b<0.2，0<c<0.3，0.67<d+e<0.8，b+c+d+e＝1。
作为上述聚阴离子化合物的示例，例如可以列举出：
A 1 fM 3 g(PO 4) iO jX 1 3-j，其中A为H、Li、Na、K及NH 4中的一种或几种，M 3为Ti、Cr、Mn、Fe、 Co、Ni、V、Cu及Zn中的一种或几种，X 1为F、Cl及Br中的一种或几种，0<f≤4，0<g≤2，1≤i≤3，0≤j≤2；
Na nM 4PO 4X 2，其中M 4为Mn、Fe、Co、Ni、Cu及Zn中的一种或几种，X 2为F、Cl及Br中的一种或几种，0<n≤2；
Na pM 5 q(SO 4) 3，其中M 5为Mn、Fe、Co、Ni、Cu及Zn中的一种或几种，0<p≤2，0<q≤2；
Na sMn tFe 3-t(PO 4) 2(P 2O 7)，其中0<s≤4，0≤t≤3，例如t为0、1、1.5、2或3。
作为上述普鲁士蓝类似物的示例，例如可以列举出：
A uM 6 v[M 7(CN) 6] w·xH 2O，其中A为H +、NH 4+、碱金属阳离子及碱土金属阳离子中的一种或几种，M 6和M 7各自独立地为过渡金属阳离子中的一种或几种，0<u≤2，0<v≤1，0<w≤1，0<x<6。例如A为H +、Li +、Na +、K +、NH 4 +、Rb +、Cs +、Fr +、Be 2+、Mg 2+、Ca 2+、Sr 2+、Ba 2+及Ra 2+中的一种或几种，M 6和M 7各自独立地为Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Zn、Sn及W中的一种或几种过渡金属元素的阳离子。
正极活性物质层还可选的包括导电剂和粘结剂，导电剂用于改善正极活性物质层的导电性，粘结剂用于将正极活性材料及粘结剂牢固地粘结于正极集流体上。本申请对导电剂和粘结剂的种类不做具体限定，可以根据实际需求进行选择。
作为示例，导电剂可以是超导碳、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一种或几种；粘结剂可以是丁苯橡胶(SBR)、水性丙烯酸树脂(water-basedacrylic resin)、羧甲基纤维素(CMC)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)及聚乙烯醇(PVA)中的一种或几种。
这些材料均可以通过商业途径获得。
[负极极片]
在钠二次电池中，所述负极极片通常包括负极集流体及设置在负极集流体上的负极膜层，所述负极膜层包括负极活性材料。
所述负极集流体可以采用常规金属箔片、涂炭金属箔材或多孔金属板等材料。作为示例，负极集流体可以采用铜箔。
所述负极活性材料的具体种类不做限制，可以采用本领域已知的能够用于钠二次电池负极的活性材料，本领域技术人员可以根据实际需求进行选择。作为示例，所述负极活性材料可以包括但不限于钠金属、碳材料、合金材料、过渡金属氧化物和/或硫化物、磷基材料、钛酸盐材料中的一种或几种。具体地，所述碳材料可选自硬碳、软碳、无定形碳、纳米结构碳材料中的一种或几种；所述合金材料可选自Si、Ge、Sn、Pb、Sb中的一种或几种形成的合金材料；所述过渡金属氧化物和硫化物的通式为M xN y，其中M为Fe、Co、Ni、Cu、Mn、Sn、Mo、Sb、V的一种或几种，N为O或S；所述磷基材料可选自红磷、白磷、黑磷中的一种或几种；所述钛酸盐材料可选自Na 2Ti 3O 7、Na 2Ti 6O 13、Na 4Ti 5O 12、Li 4Ti 5O 12、NaTi 2(PO 4) 3中的一种或几种。这些材料均可以通过商业途径获得。
所述负极膜层通常还可选地包括粘结剂和导电剂，导电剂用于提高负极活性物质层的导电性，粘结剂用于将负极活性材料及粘结剂牢固地粘结于负极集流体上。本申请对导电剂和粘结剂的种类不做具体限定，可以根据实际需求进行选择。
作为示例，导电剂可以为超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维 中一种或几种。
作为示例，粘结剂可以是丁苯橡胶(SBR)、苯乙烯-丁二烯橡胶(SBCs)、水性丙烯酸树脂(water-based acrylic resin)及羧甲基纤维素(CMC)中的一种或几种。
负极活性物质层还可选的包括增稠剂，如羧甲基纤维素(CMC)。但本申请并不限于此，本申请还可以使用其它可被用作钠离子电池负极极片增稠剂的材料。
[隔离膜]
作为上述的隔离膜，本申请并没有特别的限制，可以根据实际需求选用任意公知的具有电化学稳定性和力学稳定性的多孔结构隔离膜，例如可以是包含玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的一种或几种的单层或多层薄膜。
本申请实施例对钠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。如图1是作为一个示例的方形结构的二次电池1。
在一些实施方式中，二次电池可包括外包装。该外包装用于封装正极极片、负极极片和电解质。
在一些实施方式中，外包装可包括壳体和盖板。其中，壳体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。壳体具有与容纳腔连通的开口，盖板能够盖设于所述开口，以封闭所述容纳腔。
正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件。电极组件封装于所述容纳腔。电解质可采用电解液，电解液浸润于电极组件中。钠二次电池所含电极组件的数量可以为一个或几个，可根据需求来调节。
在一些实施方式中，钠二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳。
钠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，如可包括聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)、聚丁二酸丁二醇酯(PBS)中的一种或几种。
在一些实施方式中，钠二次电池可以组装成电池模块，电池模块所含钠二次电池的数量可以为多个，具体数量可根据电池模块的应用和容量来调节。
图2是作为一个示例的电池模块2。参照图2，在电池模块2中，多个钠二次电池1可以是沿电池模块2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钠二次电池1进行固定。
电池模块2还可以包括具有容纳空间的外壳，多个钠二次电池1容纳于该容纳空间。在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以根据电池包的应用和容量进行调节。
图3和4是作为一个示例的电池包3。参照图3和4，在电池包3中可以包括电池箱和设置于电池箱中的多个电池模块2。电池箱包括上箱体4和下箱体5，上箱体4能够盖设于下箱体5，并形成用于容纳电池模块2的封闭空间。多个电池模块2可以按照任意的方式排布于电池箱中。
[用电装置]
本申请还提供一种用电装置，所述用电装置包括所述的钠二次电池、电池模块和电池包中的至少一种。所述钠二次电池、电池模块或电池包可以作为所述用电装置的电源，也可以作为所述用电装置的能量存储单元。所述用电装置可以但不限于是移动设备(例如手机、笔记本电脑)、电动车辆(例如纯电 动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车)、电气列车、船舶及卫星、储能系统。
所述用电装置可以根据其使用需求来选择钠二次电池、电池模块或电池包。
图5是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车。为了满足该用电装置对钠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。
作为另一个示例的用电装置可以是手机、平板电脑、笔记本电脑。该用电装置通常要求轻薄化，可以采用钠二次电池作为电源。
为了使本申请实施例所解决的技术问题、技术方案及有益效果更加清楚，以下将结合实施例和附图进行进一步详细说明。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。以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本申请及其应用的任何限制。基于本申请中的实施例，本领域普通技术人员在没有付出创造性劳动前提下所获得的所有其他实施例都属于本申请保护的范围。
一、混合添加剂的制备
将氟代碳酸乙烯酯和二氟草酸硼酸钠(NaDFOB)按照质量比为10:1均匀混合，得到混合添加剂1，其中氟代碳酸乙烯酯的分子量为106.05，25℃的粘度为3.2mPa·S，主链碳原子数为3。混合添加剂2-59的组成如表1所示。
表1
Figure PCTCN2022127115-appb-000001
Figure PCTCN2022127115-appb-000002
Figure PCTCN2022127115-appb-000003
Figure PCTCN2022127115-appb-000004
Figure PCTCN2022127115-appb-000005
Figure PCTCN2022127115-appb-000006
Figure PCTCN2022127115-appb-000007
二、电解液的制备
在氩气气氛手套箱中(H 2O<0.1ppm，O 2<0.1ppm)，将电解质钠盐双(三氟甲基磺酰)亚胺钠NaTFSI和混合添加剂1，溶解于有机溶剂乙二醇二甲醚DME中，搅拌均匀，得到电解质钠盐浓度为1mol/L的电解液1，电解液2-63的组成如表2所示。
表2
Figure PCTCN2022127115-appb-000008
Figure PCTCN2022127115-appb-000009
Figure PCTCN2022127115-appb-000010
Figure PCTCN2022127115-appb-000011
Figure PCTCN2022127115-appb-000012
三、电池的制备
1、正极极片的制备
将聚偏氟乙烯粘结剂充分溶解于N甲基吡咯烷酮中，然后加入炭黑导电剂和正极活性材料Na 4Fe 3(PO 4) 2P 2O 7制成分散均匀的正极浆料(聚偏氟乙烯、炭黑导电剂和正极活性材料Na 4Fe 3(PO 4) 2P 2O 7的质量比为10:10:80)，将正极浆料均匀涂敷在铝箔两个表面，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，最后进行冲切，得到正极极片。
2、负极极片的制备
将负极活性材料硬碳、导电剂碳纳米管材料和粘结剂羧甲基纤维素钠加到水中搅拌成均匀的负极浆料(负极活性材料硬碳与导电剂碳纳米管和粘结剂羧甲基纤维素钠的质量比为94.4:4:1.6)，将负极浆料涂覆在负极集流体铜箔表面上，然后转移到真空干燥箱中完全干燥，最后进行冲切，得到负极极片。
3、电解液
电解液采用上述表2所示电解液1-63的电解液。
4、隔离膜
以聚丙烯膜作为隔离膜。
5、钠二次电池的制备
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极极片之间起到隔离的作用，然后卷绕得到电极组件；将电极组件置于外包装中，将上述制备好的电解液注入到干燥后的二次电池中，经过真空封装、静置、化成、整形工序，获得二次电池。
实施例1-48的钠二次电池的电解液分别采用表2电解液1-48；对比例1-15的钠二次电池采用表2电解液49-63。
四、电池性能测试
1、库伦效率
以实施例1为例，将制得的钠二次电池在25℃下以1/3C的恒定电流充电至4.15V，之后以4.15V恒压充电至电流降到0.05C，得到首次充电容量(C c1)；再以1/3C的恒定电流放电至2.5V，得到首次放电容量(C d1)，并按照下式计算钠二次电池库伦效率。
钠二次电池库伦效率＝首次放电容量(C d1)/首次充电容量(C c1)；
实施例2-48和对比例1-15的二次电池的库伦效率的测试过程同上。
2、容量保持率
以实施例1为例，将钠二次电池在25℃下以1C的恒定电流充电至4.15V，之后以4.15V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(C d1)；如此反复充放电至第n圈，得钠二次电池循环n圈后的放电容量，记为C dn，并按照下式计算钠二次电池容量保持率：
容量保持率＝循环n圈后的放电容量(C dn)/首圈放电容量(C d1)。
实施例2-48和对比例1-15的二次电池的库伦效率的测试过程同上。
3、直流内阻(DCR)
直流内阻(DCR)是指电流在电芯内部受到的阻力，电池在放电过程结束后，由于极化的存在，电池电压会出现反弹的现象。直流阻抗技术就是利用电池在间歇放电过程中，放电结束前一瞬间的电压与放电结束稳定后的电压差来计算电池内阻的。
以实施例1为例，将钠二次电池在25℃下以1C的恒定电流充电至4.15V，之后以4.15V恒压充电至电流降到0.05C，再以1C的恒定电流放电至2.5V，后搁置5min(稳定时间)，继续下一个循环，每个循环记录放电中止前的电池电压和电池电压稳定后的电池电压，然后利用以下公式计算直流阻抗R＝ΔU/I(其中：ΔU为电压差，R为直流电阻，I为放电电流)。
4、钠枝晶
将上述循环200圈后的钠二次电池在氩气气氛手套箱中(H 2O<0.1ppm，O 2<0.1ppm)进行拆解，目视观察负极极片表面形貌，确定是否有钠枝晶生成。负极极片无白点判定为钠枝晶情况无、负极极片有零星白点判定为钠枝晶情况轻微、负极极片有密密麻麻白点判定为钠枝晶情况严重。
实施例1-48的钠二次电池以及对比例1-15的钠二次电池的性能测试结果如表3所示。
表3
Figure PCTCN2022127115-appb-000013
Figure PCTCN2022127115-appb-000014
5、电解液中成膜剂和含氟硼酸钠以及电解质钠盐变化情况
以实施例1为例，分别取上述循环100圈和200圈后的二次电池中的电解液，采用 19F NMR光谱定量分析电池循环过程中电解液中组分变化情况。
实施例2-48和对比例1-15的二次电池的电解液组分变化测试过程同上。
实施例1-48的钠二次电池以及对比例1-15的钠二次电池的循环100圈和循环200圈后电解液中成膜剂和含氟硼酸钠以及电解质钠盐变化情况测试结果如表4所示。
表4
Figure PCTCN2022127115-appb-000015
Figure PCTCN2022127115-appb-000016
Figure PCTCN2022127115-appb-000017
成膜剂残留量％＝循环n圈后电解液中成膜剂的含量/循环前电解液中成膜剂的含量×100％
含氟硼酸钠残留量％＝循环n圈后电解液中含氟硼酸钠的含量/循环前电解液中含氟硼酸钠的含量×100％
电解质钠盐残留量％＝循环n圈后电解液中电解质钠盐的含量/循环前电解液中电解质钠盐的含量×100％。
结论：由表3可知，相较于对比例1-15，实施例1-48所得钠二次电池具有较高的库伦效率和容量保持率以及较低的DCR，并且实施例1-48所得钠二次电池的循环200圈后负极极片表面没有钠枝晶产生，由此表明本申请的混合添加剂可以提高钠二次电池的循环寿命。同时由表4可知，相较于对比例1-15，实施例1-48所得钠二次电池在经循环100圈后和200圈后电解液中成膜剂、含氟硼酸钠和电解质钠盐残留量均较高，由此表明本申请的混合添加剂可以在降低各自消耗的同时降低电解液中电解质钠盐的消耗。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围，其均应涵盖在本申请的权利要求和说明书的范围当中。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (26)

  1. 一种混合添加剂，其中，包括成膜剂和含氟硼酸钠，所述成膜剂包括氟代酯和/或氟代醚，
    其中，所述成膜剂与所述含氟硼酸钠的质量比为(5-20)：(0.5-2)。
  2. 根据权利要求1所述的混合添加剂，其中，所述氟代酯的分子量不高于800。
  3. 根据权利要求1或2所述的混合添加剂，其中，所述氟代酯上主链碳原子数不大于10。
  4. 根据权利要求1-3中任一项所述的混合添加剂，其中，所述氟代酯在25℃的粘度不高于5mPa·S。
  5. 根据权利要求1-4中任一项所述的混合添加剂，其中，所述氟代酯包括氟代碳酸乙烯酯、三氟乙基甲基碳酸酯、二氟代碳酸乙烯酯、双氟碳酸丙烯酯、三氟代乙酸乙酯、三氟甲基碳酸乙烯酯、4-三氟代甲基碳酸乙烯酯、二(2,2,2-三氟乙基)碳酸酯、三氟丙酸甲酯、3,3,3-三氟代乙酸乙酯、2-三氟甲基苯甲酸甲酯、4,4,4-三氟丁酸乙酯、1,1,1,3,3,3-六氟异丙基丙烯酸酯、氟代丁酸丙酯、氟代乙酸丙酯、氟代乙酸异丙酯、氟代丙酸丁酯、氟代丙酸异丙酯、氟代丁酸乙酯，氟代丙酸甲酯、氟代丙酸乙酯和氟代丙酸丙酯中的至少之一。
  6. 根据权利要求1-5中任一项所述的混合添加剂，其中，所述氟代醚的分子量不高于800。
  7. 根据权利要求1-6中任一项所述的混合添加剂，其中，所述氟代醚上主链碳原子数不大于10。
  8. 根据权利要求1-7中任一项所述的混合添加剂，其中，所述氟代醚在25℃的粘度不高于2mPa·S。
  9. 根据权利要求1-8中任一项所述的混合添加剂，其中，所述氟代醚包括1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚、双(2,2,2-三氟乙基)醚、甲基九氟丁醚、乙基九氟丁基醚、2,2,2-三氟乙基甲基醚、1,1,1,3,3,3-六氟-2-(氟甲氧基)丙烷、1,1,2,2-四氟乙基-2,2,2-三氟乙醚、2,2,2-三氟乙基乙烯基醚、聚全氟甲基异丙基醚、2,2,3,3,3-五氟丙基-1,1,2,2-四氟乙醚、二氟甲基-2,2,3,3-四氟丙基醚、2,2,3,3-四氟-1-甲氧基丙烷、1,1,2,2-四氟乙基乙醚、1,1,2,3,3,3-六氟丙基甲醚、乙基全氟丁基醚、七氟丙基-1,2,2,2-四氟乙醚、1,1,2,3,3,3-五氟丙基-2,2,2-三氟乙醚、2,2,3,3,3-五氟丙基二氟甲醚、2-全氟丙氧基全氟丙基三氟乙烯基醚、2,3,3,3-四氟-2-(七氟丙氧基)丙酰氟化物、烯丙基-2,2,3,3-四氟丙醚、烯丙基-1,1,2,2-四氟乙基醚、叔丁基-1,1,2,2-四氟乙基醚和2,2,2-三氟乙基乙基醚中的至少之一。
  10. 根据权利要求1-9中任一项所述的混合添加剂，其中，所述含氟硼酸钠包括四氟硼酸钠、二氟草酸硼酸钠、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和氰基三(2,2,2三氟乙基)硼酸钠中的至少之一。
  11. 根据权利要求1-10中任一项所述的混合添加剂，其中，所述成膜剂包括氟代酯和氟代醚，所述氟代酯和氟代醚的质量比为(0.05-0.95)：(0.05-0.95)。
  12. 一种钠二次电池用电解液，其中，包括电解质钠盐、有机溶剂和添加剂，其中，所述添加剂包括权利要求1-11中任一项所述的混合添加剂。
  13. 根据权利要求12所述的钠二次电池用电解液，其中，在所述电解液中，所述混合添加剂中的含氟硼酸钠的浓度为0.5wt％-2wt％。
  14. 根据权利要求12或13所述的钠二次电池用电解液，其中，所述电解液中成膜剂的浓度为5wt％-20wt％。
  15. 根据权利要求12-14中任一项所述的钠二次电池用电解液，其中，所述电解液中电解质钠盐的 浓度为0.5mol/L-8mol/L。
  16. 根据权利要求12-15中任一项所述的钠二次电池用电解液，其中，所述电解质钠盐包括六氟磷酸钠、二氟草酸硼酸钠、四氟硼酸钠、双草酸硼酸钠、高氯酸钠、六氟砷酸钠、双(氟磺酰)亚胺钠、三氟甲基磺酸钠和双(三氟甲基磺酰)亚胺钠中的至少之一。
  17. 根据权利要求12-16中任一项所述的钠二次电池用电解液，其中，所述有机溶剂包括酯类溶剂、砜类溶剂、醚类溶剂和腈类溶剂中的至少之一。
  18. 根据权利要求12-17中任一项所述的钠二次电池用电解液，其中，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、二苯醚和冠醚中的至少之一。
  19. 根据权利要求12-18中任一项所述的钠二次电池用电解液，其中，所述电解液在25℃下的粘度不高于8mPa·S。
  20. 根据权利要求12-19中任一项所述的钠二次电池用电解液，其中，所述电解液在25℃下的离子电导率为0.5mS/cm-20mS/cm。
  21. 一种钠二次电池，其中，所述钠二次电池包括正极极片、负极极片、隔离膜和电解液，所述电解液包括权利要求1-11中任一项所述的混合添加剂或所述电解液为权利要求12-20中任一项所述的钠二次电池用电解液。
  22. 根据权利要求21所述的钠二次电池，其中，所述正极极片中正极活性材料包括层状过渡金属氧化物、聚阴离子化合物和普鲁士蓝类似物中的至少之一。
  23. 根据权利要求21或22所述的钠二次电池，其中，所述负极极片中负极活性材料包括钠金属、碳材料、合金材料、过渡金属氧化物和/或硫化物、磷基材料、钛酸盐材料中的至少之一。
  24. 一种电池模块，其中，所述电池模块包括权利要求21-23中任一项所述的钠二次电池。
  25. 一种电池包，其中，所述电池包包括权利要求21-23中任一项所述的钠二次电池和权利要求24所述的电池模块中的至少一种。
  26. 一种用电装置，其中，所述用电装置包括权利要求21-23中任一项所述的钠二次电池、权利要求24所述的电池模块和权利要求25所述的电池包中的至少一种。
PCT/CN2022/127115 2022-10-24 2022-10-24 混合添加剂、钠二次电池用电解液、钠二次电池、电池模块、电池包及用电装置 WO2024086987A1 (zh)

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KR20200040441A (ko) * 2018-10-10 2020-04-20 울산과학기술원 가역적 나트륨 공기 이차전지 및 이의 제조방법
CN111082140A (zh) * 2019-12-19 2020-04-28 东莞市坤乾新能源科技有限公司 一种新型钠离子电池电解液和钠电池
CN113809398A (zh) * 2021-08-12 2021-12-17 东莞市创明电池技术有限公司 电解液添加剂、电解液和钠二次电池
CN115064771A (zh) * 2022-06-23 2022-09-16 华中科技大学 一种钠离子电池电解液、电池和应用
CN115191040A (zh) * 2020-01-21 2022-10-14 新加坡国立大学 Na过量P3型层状氧化物NaxMyOz其中x≥0.66、0.8≤y≤1.0且z≤2作为钠离子电池的阴极材料

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20200040441A (ko) * 2018-10-10 2020-04-20 울산과학기술원 가역적 나트륨 공기 이차전지 및 이의 제조방법
CN111082140A (zh) * 2019-12-19 2020-04-28 东莞市坤乾新能源科技有限公司 一种新型钠离子电池电解液和钠电池
CN115191040A (zh) * 2020-01-21 2022-10-14 新加坡国立大学 Na过量P3型层状氧化物NaxMyOz其中x≥0.66、0.8≤y≤1.0且z≤2作为钠离子电池的阴极材料
CN113809398A (zh) * 2021-08-12 2021-12-17 东莞市创明电池技术有限公司 电解液添加剂、电解液和钠二次电池
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