WO2024109853A1 - 一种基于负极原位补锂的锂离子电池及其制备方法 - Google Patents

一种基于负极原位补锂的锂离子电池及其制备方法 Download PDF

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WO2024109853A1
WO2024109853A1 PCT/CN2023/133460 CN2023133460W WO2024109853A1 WO 2024109853 A1 WO2024109853 A1 WO 2024109853A1 CN 2023133460 W CN2023133460 W CN 2023133460W WO 2024109853 A1 WO2024109853 A1 WO 2024109853A1
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lithium
negative electrode
ether
electrolyte
ion battery
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PCT/CN2023/133460
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English (en)
French (fr)
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欧学武
林雨薇
韩晓琪
唐永炳
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中国科学院深圳先进技术研究院
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/058Construction or manufacture
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/48Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/48Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

Definitions

  • the present invention belongs to the technical field of batteries, and in particular relates to a lithium-ion battery based on negative electrode in-situ lithium supplementation and a preparation method thereof.
  • lithium metal negative electrode is an ideal choice for high specific energy lithium-ion batteries. Lithium metal batteries are considered to be one of the most promising next-generation high-energy density storage devices.
  • negative electrode does not have any active materials (such as graphite, Li, Si, Sn), but only uses a conductive current collector (such as copper foil) as the negative electrode, and the positive electrode is a common lithium-containing material (such as lithium iron phosphate, ternary positive electrode, lithium cobalt oxide, etc.).
  • a conductive current collector such as copper foil
  • the working principle of negative electrode-free lithium metal batteries is different from that of traditional lithium-ion batteries.
  • lithium ions When charging, lithium ions combine with electrons on the surface of the negative electrode conductive current collector, and lithium deposition occurs; during the discharge process, the lithium metal deposited on the negative electrode conductive current collector is stripped and returns to the positive electrode through the electrolyte.
  • the deposition/stripping process of lithium causes a large volume change of the lithium metal negative electrode, resulting in repeated formation and destruction of the SEI film in the traditional electrolyte system, consuming a large amount of lithium ions.
  • the negative electrode current collector is subjected to surface oxidation treatment to generate Cu(OH) 2 , and then annealed to obtain a copper foil with a lithium-philic nano-cuprous oxide surface layer, which helps to form a stable SEI film, promotes uniform deposition of lithium, inhibits dendrite growth, and improves battery performance (patent CN115064700A).
  • adding lithium-rich materials to the positive electrode active material and utilizing its high irreversible lithium desorption capacity to compensate for the irreversible loss of lithium on the negative electrode side during subsequent cycles can extend the battery cycle life (patent CN114284567A).
  • the present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art.
  • the present invention proposes a lithium-ion battery based on in-situ lithium supplementation of the negative electrode, in which the electrolyte inside can provide additional active lithium for the lithium-ion battery system to slow down the attenuation of the battery and improve the cycle stability of the battery.
  • the first aspect of the present invention provides a lithium-ion battery based on in-situ lithium replenishment of the negative electrode, the lithium-ion battery based on in-situ lithium replenishment of the negative electrode comprising a positive electrode, a negative electrode, and a separator and an electrolyte between the positive electrode and the negative electrode; the electrolyte comprises a lithium salt and a negative electrode lithium replenishment additive; the negative electrode lithium replenishment additive decomposes to generate free radicals or positively charged functional groups under a charging voltage of 4V or above; the free radicals or positively charged functional groups combine with anions in the lithium salt.
  • the free radicals described in the present invention refer to hydrogen free radicals, alkyl free radicals, alkoxy free radicals, etc.; the functional group refers to a positively charged ion centered on carbon or nitrogen.
  • the free radicals or positively charged functional groups described in the present invention combine with the anions in the lithium salt in two cases: one is that the positively charged functional groups combine with the anions without causing damage to the anions, such as the combination of CH 3 H 2 C + and FSI - anions; the other is that the free radicals react with the anions to consume the anions, such as the reaction of hydrogen free radicals with hexafluorophosphate to generate HF and PF 5 , thereby consuming the anions.
  • the main inventive concept of the present invention is that: those skilled in the art know that charge neutrality must be ensured inside the electrolyte system, whether it is during the charging and discharging process or the battery static process. For example, if an electron-consuming reaction occurs at the negative electrode that consumes lithium cations, the positive electrode will be forced to insert additional anions for charge compensation to ensure charge neutrality in the electrolyte.
  • the solvent or additive in the electrolyte decomposes, further combines with or reacts with the anions in the lithium salt to consume the anions, then in order to ensure the electronic charge neutrality between the electrodes, the excess cations (that is, lithium ions) will be deposited on the surface of the negative electrode current collector, or compensate for the part of lithium consumed by the formation of the SEI film on the negative electrode side.
  • the present invention adds a negative electrode lithium supplement additive that is easily decomposed under high voltage (above 4V) conditions.
  • the negative electrode lithium supplement additive decomposes during the charging process to produce free radicals or positively charged functional groups, which combine with or react with the anions of the lithium salt to consume the anions, so that part of the lithium ions in the electrolyte are converted into active lithium ions, thereby depositing or supplementing a part of the lithium consumed by the negative electrode side during the formation of the SEI film on the negative electrode side.
  • This not only ensures the formation of a stable SEI film, but also supplements the negative electrode with lithium in situ, so that the negative electrode-free lithium metal battery can circulate stably for a longer period of time without failure.
  • the negative electrode in-situ lithium supplementation technology of the present invention only needs to regulate the electrolyte components, and can provide a large amount of active lithium through the neutral charge characteristics of the electrolyte to achieve the long cycle performance of the negative electrode-free lithium metal battery.
  • the electrolyte of the present invention is also suitable for other lithium ion battery systems based on graphite negative electrodes, silicon-carbon negative electrodes, alloyed negative electrodes, etc., by effectively supplementing the irreversible loss of active lithium ions in the process of forming SEI on the negative electrode side, thereby improving the cycle life of the battery.
  • the working mechanism of the negative electrode in-situ lithium supplementation of the present invention is as follows: during the battery charging process, when charged to a certain voltage (above 4V), the negative electrode lithium supplementation additive in the electrolyte first decomposes to produce free radicals or positively charged functional groups, and the reaction consumes the anions in the lithium salt or combines with the anions; because the electrolyte needs to maintain electrical neutrality, part of the lithium ions in the electrolyte will be converted into active lithium ions to deposit on the negative electrode side or supplement part of the lithium consumed in the formation of the SEI film on the negative electrode side.
  • the concentration or type of the negative electrode lithium supplementation additive can be changed to achieve different degrees of lithium supplementation effect; due to the different charging and discharging platforms of different positive electrode materials, for systems with low charging and discharging platforms, it can be selected to charge to high voltage (above 4V) in the first few cycles to allow the negative electrode lithium supplementation additive to decompose, and after achieving a lithium supplementation effect, charge and discharge in a suitable voltage range.
  • the negative electrode in-situ lithium supplementation method of the present invention can effectively slow down the attenuation of the battery and extend the battery failure time.
  • the negative electrode lithium supplement additive is selected from one or more of ester compounds, ether compounds, olefin compounds, and lithium-containing compounds.
  • the ester compound of the present invention refers to a class of organic compounds generated by the reaction of acid (carboxylic acid or inorganic oxygen-containing acid) and alcohol, such as vinylene carbonate, vinyl ethylene carbonate, vinyl acetate, etc.
  • ether compounds refer to compounds containing ether bonds, such as ethylene glycol dimethyl ether, ethylene glycol phenyl ether, ethylene glycol diphenyl ether, phenylene sulfide, etc.
  • the negative electrode lithium supplement additive includes vinyl carbonate, vinyl ethylene carbonate, vinyl acetate, trimethyl vinyl acetate, lithium difluorophosphate, lithium difluorooxalate borate, ethylene glycol dimethyl ether, ethylene glycol phenyl ether, ethylene glycol diphenyl ether, benzene sulfide, tert-butyl phenyl ether, chloromethyl benzene sulfide, epoxypropyl methyl ether, tetrahydrofuran, 2,3-dichlorotetrahydrofuran, tetrahydrofuran chloride, bis (2-chloroethoxy) methane, ethyl propyl ether, methyl butyl ether, dichloromethyl butyl ether, methyl propyl sulfide, methyl propyl ether, butyl phenyl ether, 1,2-dichloroethoxyethane, chloromethyl iso
  • the mass percentage of the negative electrode lithium supplement additive in the electrolyte is 0.1-10%.
  • the mass percentage of the negative electrode lithium supplement additive in the electrolyte is 1-5%.
  • the lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(trifluoromethylsulfonyl)imide, lithium tetrafluoroborate, lithium sulfate, lithium nitrate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethylsulfonyl)imide, and lithium perchlorate.
  • the concentration of the lithium salt in the electrolyte is 0.1-10 mol/L.
  • the concentration of the lithium salt in the electrolyte is 1-5 mol/L.
  • the electrolyte further comprises an organic solvent
  • the organic solvent is selected from one or more of ester compounds, sulfone compounds, ether compounds, nitrile compounds, and carboxylic acid ester compounds.
  • the nitrile compound of the present invention refers to an organic compound formed by connecting carbon atoms containing a hydrocarbon group and a cyano group, such as succinonitrile, adiponitrile, etc.
  • the organic solvent includes one or more of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl formate, methyl acetate, N,N-dimethylacetamide, fluoroethylene carbonate, methyl propionate, ethyl propionate, ethyl acetate, ⁇ -butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, dipropylene glycol dimethyl ether, 1,2-dimethoxypropane, triethylene glycol dimethyl ether, dimethyl sulfone, cyclopentane, dimethyl ether, vinyl sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, and 12-crown ether-4.
  • propylene carbonate ethylene carbonate
  • the electrolyte further comprises an electrolyte additive, and the electrolyte additive is selected from one or more of ester compounds, sulfone compounds, ether compounds, nitrile compounds, and olefin compounds.
  • the electrolyte additive is selected from one or more of ester compounds, sulfone compounds, ether compounds, nitrile compounds, and olefin compounds.
  • the electrolyte additive includes one or more of fluoroethylene carbonate, vinylene carbonate, ethylene carbonate, 1,3-propane sultone, 1,4-butane sultone, vinyl sulfate, propylene sulfate, ethylene sulfate, vinyl sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, ethylene sulfite, methyl chloroformate, and tris(trimethylsilyl)phosphate.
  • the negative electrode adopts a negative electrode current collector
  • the material of the negative electrode current collector is selected from metal copper foil, nickel foil, titanium foil, nickel mesh, foam copper plate, porous copper skeleton, conductive carbon skeleton, carbon nanofiber scaffold or mesoporous carbon nanofiber.
  • the negative electrode current collector is a negative electrode current collector that has undergone surface modification or three-dimensional current collector design.
  • the surface modification includes but is not limited to coating a polymer coating or a fast ion conductor layer on the surface of the negative electrode current collector; or constructing an artificial SEI film on the surface of the negative electrode current collector before battery assembly.
  • the three-dimensional current collector design includes but is not limited to three-dimensional structuring of the negative electrode current collector such as copper foil, carbon substrate, porous foam copper plate and polymer substrate.
  • the surface of the negative electrode current collector is coated with a negative electrode active material.
  • the negative electrode active material includes one or more of graphite, activated carbon, hard carbon, lithium titanate, graphene, carbon nanotubes, silicon carbon, metal oxides, aluminum, tin, bismuth, and antimony.
  • the metal oxide includes one or more of manganese oxide, tin oxide, and nickel oxide.
  • the positive electrode comprises a positive electrode current collector
  • the material of the positive electrode current collector is selected from one or more of aluminum, tin, copper, iron, nickel, titanium, magnesium, and zinc.
  • the surface of the positive electrode current collector is coated with a positive electrode active material
  • the positive electrode active material includes one or more of lithium cobalt oxide, lithium iron phosphate, ternary material, lithium manganese oxide, lithium nickel manganese oxide, natural graphite, expanded graphite, conductive carbon black, graphene, carbon nanotubes, activated carbon fibers, and carbon molecular sieves.
  • the material of the separator is selected from glass fiber, polyethylene, polypropylene or polypropylene/polyethylene/polypropylene.
  • the lithium-ion battery based on in-situ lithium supplementation of the negative electrode is a negative electrode-free lithium metal battery.
  • the second aspect of the present invention provides a method for preparing a lithium-ion battery based on in-situ lithium replenishment of the negative electrode according to the present invention, comprising the following steps:
  • the positive electrode, the negative electrode, the separator and the electrolyte are assembled to obtain the lithium-ion battery based on in-situ lithium supplementation of the negative electrode.
  • the third aspect of the present invention provides an application of an electrolyte in lithium replenishment of the negative electrode of a lithium ion battery, wherein the electrolyte comprises a lithium salt and a negative electrode lithium replenishment additive; the negative electrode lithium replenishment additive decomposes to generate free radicals or positively charged functional groups under a charging voltage of 4V or above, and the free radicals or positively charged functional groups combine with anions in the lithium salt.
  • the lithium-ion battery based on in-situ lithium replenishment of the negative electrode of the present invention adds a negative electrode lithium replenishment additive to the electrolyte.
  • the negative electrode lithium replenishment additive decomposes to produce free radicals or positively charged functional groups under the condition of a charging voltage of 4V or above, which can react to consume anions or combine with anions in lithium salts, so that part of the lithium ions in the electrolyte are converted into active lithium ions.
  • the active lithium ions are deposited on the negative electrode side or replenish part of the lithium consumed in the process of forming the SEI film on the negative electrode side, thereby achieving the effect of in-situ lithium replenishment of the negative electrode, thereby improving the cycle stability of the battery; the negative electrode-free lithium metal battery based on in-situ lithium replenishment of the negative electrode of the present invention can achieve a capacity retention rate of 78.5% after 50 cycles.
  • the electrolyte in the lithium-ion battery based on in-situ lithium replenishment of the negative electrode of the present invention has good compatibility with existing battery processes and can be applied to different types of battery systems; in addition, different negative electrode lithium replenishment additives can be selected according to different electrolyte systems, and the concentration or type of the negative electrode lithium replenishment additives can be changed to achieve different lithium replenishment effects, which has a certain degree of controllability.
  • FIG1 is a graph showing the first cycle charge and discharge three-electrode test curves of the dual-ion batteries of Example 83 and Comparative Example 2 at room temperature and a rate of 0.2C.
  • Figure 2 is a cycle performance curve of Example 83 and Comparative Example 2 at room temperature and 1C rate.
  • the electrolyte is composed of an organic solvent, a lithium salt and a negative electrode lithium replenishing additive that is easily decomposed under high pressure.
  • the organic solvent is fluoroethylene carbonate
  • the lithium salt is lithium bis(fluorosulfonyl)imide
  • the molar concentration of the lithium salt in the electrolyte is 5 mol/L
  • the negative electrode lithium replenishing additive is ethylene glycol dimethyl ether
  • the mass fraction of the negative electrode lithium replenishing additive in the electrolyte is 1 wt.%.
  • lithium iron phosphate (LFP) is used as the positive electrode material
  • carbon black is used as the conductive agent
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • negative electrode 1 Soak the copper foil in 1 mol/L hydrochloric acid solution for 10 min, take it out and rinse it with deionized water and acetone respectively, transfer it to a glove box after vacuum drying, and obtain the negative electrode sheet.
  • the electrolyte consists of an organic solvent, a lithium salt and a negative electrode lithium replenishing additive that is easily decomposed under high pressure.
  • the organic solvent is fluoroethylene carbonate
  • the lithium salt is lithium bis(fluorosulfonyl)imide
  • the molar concentration of the lithium salt in the electrolyte is 5 mol/L
  • the negative electrode lithium replenishing additive is ethylene glycol dimethyl ether
  • the mass fraction of the negative electrode lithium replenishing additive in the electrolyte is 2 wt.%.
  • the preparation of the positive electrode, treatment of the negative electrode and assembly method of the negative electrode-free lithium metal battery are the same as those in Example 1, with the only difference being that in the assembly of the negative electrode-free lithium metal battery, electrolyte 2 is used for assembly.
  • the electrolyte consists of an organic solvent, a lithium salt and a negative electrode lithium replenishing additive that is easily decomposed under high pressure.
  • the organic solvent is fluoroethylene carbonate
  • the lithium salt is lithium bis(fluorosulfonyl)imide
  • the molar concentration of the lithium salt in the electrolyte is 5 mol/L
  • the negative electrode lithium replenishing additive is ethylene glycol dimethyl ether
  • the mass fraction of the negative electrode lithium replenishing additive in the electrolyte is 5 wt.%.
  • the preparation of the positive electrode, treatment of the negative electrode and assembly method of the negative electrode-free lithium metal battery are the same as those in Example 1, with the only difference being that in the assembly of the negative electrode-free lithium metal battery, electrolyte 3 is used for assembly.
  • the electrolyte consists of an organic solvent, a lithium salt, conventional additives and a negative electrode lithium replenishing additive that is easily decomposed under high pressure.
  • the organic solvent is ethylene carbonate: diethyl carbonate (1:1, v:v)
  • the lithium salt is lithium hexafluorophosphate
  • the molar concentration of the lithium salt in the electrolyte is 1.0 mol/L.
  • the conventional additive is fluoroethylene carbonate with a mass fraction of 2wt.%.
  • the negative electrode lithium replenishing additive is ethylene glycol dimethyl ether, and the mass fraction of the negative electrode lithium replenishing additive in the electrolyte is 2wt.%.
  • lithium manganese oxide is used as the positive electrode material
  • carbon black is used as the conductive agent
  • PVDF polyvinylidene fluoride
  • the three are mixed evenly in N-methylpyrrolidone (NMP) in a ratio of 8:1:1, coated on aluminum foil, dried and cut into 10 mm discs, and vacuum dried to obtain the positive electrode sheet.
  • NMP N-methylpyrrolidone
  • the treatment and assembly method of the negative electrode of the negative electrode-free lithium metal battery is the same as that in Example 1, the difference is that in the assembly of the negative electrode-free lithium metal battery, the positive electrode 2 and the electrolyte 4 are used for assembly.
  • the electrolyte consists of an organic solvent, a lithium salt, conventional additives and a negative electrode lithium replenishing additive that is easily decomposed under high pressure.
  • the organic solvent is ethylene carbonate: diethyl carbonate (1:1, v:v)
  • the lithium salt is lithium hexafluorophosphate
  • the molar concentration of the lithium salt in the electrolyte is 1 mol/L.
  • the conventional additive is vinylene carbonate with a mass fraction of 2wt.%.
  • the negative electrode lithium replenishing additive is ethylene glycol dimethyl ether, and the mass fraction of the negative electrode lithium replenishing additive in the electrolyte is 2wt.%.
  • NCM523 is used as the positive electrode material
  • carbon black is used as the conductive agent
  • PVDF polyvinylidene fluoride
  • the three are mixed evenly in N-methylpyrrolidone (NMP) in a ratio of 8:1:1, coated on aluminum foil, dried and cut into 10 mm discs, and vacuum dried to obtain the positive electrode sheet.
  • NMP N-methylpyrrolidone
  • the treatment and assembly method of the negative electrode of the negative electrode-free lithium metal battery is the same as that in Example 1, the difference is that in the assembly of the negative electrode-free lithium metal battery, the positive electrode 3 and the electrolyte 5 are used for assembly.
  • the electrolyte is composed of an organic solvent, a lithium salt, conventional additives and a negative electrode lithium replenishing additive that is easily decomposed under high pressure.
  • the organic solvent is fluoroethylene carbonate: ethyl methyl carbonate (3:7, v:v)
  • the lithium salt is lithium hexafluorophosphate
  • the molar concentration of the lithium salt in the electrolyte is 1 mol/L.
  • the conventional additive is vinylene carbonate with a mass fraction of 2wt.%.
  • the negative electrode lithium replenishing additive is ethylene glycol dimethyl ether, and the mass fraction of the negative electrode lithium replenishing additive in the electrolyte is 2wt.%.
  • NCM811 is used as the positive electrode material
  • carbon black is used as the conductive agent
  • PVDF polyvinylidene fluoride
  • the three are mixed evenly in N-methylpyrrolidone (NMP) in a ratio of 8:1:1, coated on aluminum foil, dried and cut into 10 mm discs, and vacuum dried to obtain the positive electrode sheet.
  • NMP N-methylpyrrolidone
  • the treatment and assembly method of the negative electrode of the negative electrode-free lithium metal battery is the same as that in Example 1, the difference is that in the assembly of the negative electrode-free lithium metal battery, the positive electrode 4 and the electrolyte 6 are used for assembly.
  • the electrolyte is composed of an organic solvent, a lithium salt and a negative electrode lithium replenishing additive that is easily decomposed under high pressure.
  • the organic solvent is fluoroethylene carbonate: 2,2,2-trifluoroethyl ether (2:1, v:v)
  • the lithium salt is lithium bistrifluoromethanesulfonyl imide (LiTFSI)
  • the molar concentration of the lithium salt in the electrolyte is 2 mol/L.
  • the negative electrode lithium replenishing additive is lithium difluorophosphate, and the mass fraction of the negative electrode lithium replenishing additive in the electrolyte is 2wt.%.
  • the treatment and assembly method of the negative electrode of the negative electrode-free lithium metal battery is the same as that in Example 1, and the preparation of the positive electrode is the same as that in Example 6, the difference is that in the assembly of the negative electrode-free lithium metal battery, the positive electrode 4 and the electrolyte 7 are used for assembly.
  • electrolyte 8 It is composed of an organic solvent and a lithium salt.
  • the organic solvent is fluoroethylene carbonate
  • the lithium salt is lithium bis(fluorosulfonyl)imide
  • the molar concentration of the lithium salt in the electrolyte is 5 mol/L.
  • the preparation of the positive electrode, treatment of the negative electrode and assembly method of the negative electrode-free lithium metal battery are the same as those in Example 1, with the only difference being that in the assembly of the negative electrode-free lithium metal battery, electrolyte 8 is used for assembly.
  • the battery was first charged and discharged for five cycles at a rate of 0.2C and a charge and discharge voltage range of 3-5V (the charge cut-off voltage was higher than the decomposition voltage of the negative electrode lithium supplement additive), and then charged and discharged at a constant current of 0.2C, with a charge and discharge voltage range of 2.5-4.2V.
  • the test results are shown in Table 1:
  • Example 1 142.9 73.5 63.1
  • Example 2 144.5 71.2 72.5
  • Example 3 143.2 74.6 69.8
  • Example 4 132.4 69.3 58.2
  • Example 5 104.6 84.5 73.1
  • Example 6 185.7 75.1 71.9
  • Example 7 178.3 56.7 68.6 Comparative Example 1 140.1 80.0 50.7
  • the present invention provides additional active lithium for the battery system by adding a high-voltage easily decomposable negative electrode lithium supplement additive to the electrolyte, and consumes anions in the electrolyte to slow down the decay of the battery and improve the battery cycle stability. Due to the addition of the negative electrode lithium supplement additive, the cycle performance of the negative electrode-free lithium metal battery in Examples 1-7 of the present invention is effectively improved. After 50 cycles, the capacity retention rate is about 72%, while the negative electrode-free lithium metal battery assembled in Comparative Example 1 has a rapid capacity decay after 50 cycles, and the capacity retention rate is only about 51%. Therefore, the negative electrode lithium supplement additive of Examples 1-7 can improve the cycle performance of the negative electrode-free lithium metal battery.
  • Example 8-55 The difference between Example 8-55 and Example 1 is only the type or concentration of the negative electrode lithium supplement additive, as shown in Table 2.
  • the negative electrode-free lithium metal battery prepared in Example 8-55 was subjected to electrochemical performance testing, and the test results are shown in Table 2:
  • Examples 8-55 use different negative electrode lithium replenishing additives, among which Example 24 adding 2wt.% dipropylene glycol dimethyl ether shows better first cycle efficiency and capacity retention rate. Compared with the battery assembled with the electrolyte without adding the negative electrode lithium replenishing additive, the lithium replenishing effect is obvious.
  • Example 5 The difference between Examples 56-62 and Example 5 is only that the types or concentrations of conventional additives added to the prepared electrolytes are different, as shown in Table 3.
  • the batteries assembled in Examples 56-62 were subjected to electrochemical performance tests, and the test results are shown in Table 3:
  • Example 63-82 The difference between Examples 63-82 and Example 1 is only that the type or concentration of the organic solvent in the prepared electrolyte is different, as shown in Table 4.
  • the batteries assembled in Examples 63-82 were subjected to electrochemical performance tests, and the test results are shown in Table 4:
  • the ratios between the organic solvents in Table 4 are volume ratios.
  • Examples 63-82 added high-voltage and easily decomposable negative electrode lithium replenishing additives, which can achieve lithium replenishment to a certain extent in different electrolyte organic solvents and improve the cycle stability of the battery.
  • Lithium-ion/dual-ion batteries based on traditional negative electrode materials Lithium-ion/dual-ion batteries based on traditional negative electrode materials
  • the electrolyte is composed of an organic solvent, a lithium salt and a negative electrode lithium replenishing additive.
  • the organic solvent is ethyl methyl carbonate
  • the lithium salt is lithium hexafluorophosphate
  • the molar concentration of the lithium salt in the electrolyte is 4 mol/L
  • the negative electrode lithium replenishing additive is vinylene carbonate
  • the mass fraction of the negative electrode lithium replenishing additive in the electrolyte is 2wt.%.
  • Expanded graphite (EG) is used as the positive electrode material
  • carbon black is used as the conductive agent
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • NMP N-methylpyrrolidone
  • Embodiment 84 is a diagrammatic representation of Embodiment 84.
  • the electrolyte is composed of an organic solvent, a lithium salt and a negative electrode lithium replenishing additive, the organic solvent is ethyl methyl carbonate:ethylene carbonate:dimethyl carbonate (1:1:1, v:v:v), the lithium salt is lithium hexafluorophosphate, the molar concentration of the lithium salt in the electrolyte is 1 mol/L, the negative electrode lithium replenishing additive is vinylene carbonate, and the mass fraction of the negative electrode lithium replenishing additive in the electrolyte is 2wt.%.
  • the organic solvent is ethyl methyl carbonate:ethylene carbonate:dimethyl carbonate (1:1:1, v:v:v)
  • the lithium salt is lithium hexafluorophosphate
  • the molar concentration of the lithium salt in the electrolyte is 1 mol/L
  • the negative electrode lithium replenishing additive is vinylene carbonate
  • the mass fraction of the negative electrode lithium replenishing additive in the electrolyte is 2wt.%.
  • Preparation of negative electrode 3 Use silicon-carbon alloy powder as negative electrode material, conductive carbon black as conductive agent, CMC and SBR as binders, mix the four in pure water in the ratio of 70%, 10%, 10%, and 10%, coat them on copper foil, dry them and cut them into 12mm discs, and obtain negative electrode sheets after vacuum drying.
  • the electrolyte consists of an organic solvent and a lithium salt.
  • the organic solvent is ethyl methyl carbonate
  • the lithium salt is lithium hexafluorophosphate
  • the molar concentration of the lithium salt in the electrolyte is 4 mol/L.
  • the electrolyte consists of an organic solvent and a lithium salt.
  • the organic solvent is ethyl methyl carbonate:ethylene carbonate:dimethyl carbonate (1:1:1, v:v:v).
  • the lithium salt is lithium hexafluorophosphate.
  • the molar concentration of the lithium salt in the electrolyte is 1 mol/L.
  • the preparation and assembly methods of the positive and negative electrodes of the lithium-ion battery are the same as those of Example 84, with the only difference being that electrolyte 12 is used for assembly of the lithium-ion battery.
  • the electrolyte consists of an organic solvent and a lithium salt.
  • the organic solvent is ethyl methyl carbonate:ethylene carbonate:dimethyl carbonate (1:1:1, v:v:v).
  • the lithium salt is lithium hexafluorophosphate.
  • the molar concentration of the lithium salt in the electrolyte is 1 mol/L.
  • Example 83 The electrochemical performance tests of the dual-ion batteries assembled in Example 83 and Comparative Example 2 were performed using the Xinwei testing system.
  • Figure 1 is a three-electrode test curve of the first cycle of charge and discharge of the dual-ion battery of Example 83 of the present invention and Comparative Example 2 at room temperature (about 25°C) and a rate of 0.2C, wherein Figure 1 (a) is a three-electrode test curve of the first cycle of charge and discharge of Comparative Example 2, and Figure 1 (b) is a three-electrode test curve of the first cycle of charge and discharge of Example 83.
  • Figure 2 is a cycle performance curve of Example 83 of the present invention and Comparative Example 2 at room temperature and a rate of 1C.
  • VC vinylene carbonate
  • the batteries assembled in Examples 84 and 86 were first charged and discharged at a rate of 0.2C and a charge and discharge voltage range of 3-4.6V, and the batteries assembled in Examples 85 and 87 were charged and discharged at a rate of 0.2C and a charge and discharge voltage range of 3-4.8V for the first five cycles (the charging cut-off voltage was higher than the decomposition voltage of the negative electrode lithium supplement additive), and then charged and discharged at a constant current of 0.2C, and the charge and discharge voltage range was 2.5-4.2V.
  • Table 5 The test results are shown in Table 5:
  • Examples 84-87 use different negative electrodes and positive electrodes. Under the condition of adding high-voltage and easily decomposable negative electrode lithium replenishing additives, they can also achieve the effect of in-situ lithium replenishing of the negative electrode, thereby increasing the cycle stability and capacity retention rate of the battery.

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Abstract

本发明属于电池技术领域,公开了一种基于负极原位补锂的锂离子电池及其制备方法。本发明基于负极原位补锂的锂离子电池包括正极、负极、隔膜和电解液;电解液包括锂盐和负极补锂添加剂;负极补锂添加剂在充电电压为4V以上的条件下,分解产生自由基或带正电的官能团,能够与锂盐中的阴离子结合。本发明基于负极原位补锂的锂离子电池中的负极补锂添加剂,在充电电压为4V以上的条件下,分解产生自由基或带正电的官能团,能够发生反应消耗阴离子或与锂盐中的阴离子结合,使电解液中的部分锂离子转变为活性锂离子,活性锂离子在负极侧沉积或补充负极侧在形成SEI膜过程中消耗的一部分锂,由此达到负极原位补锂的效果,提高电池的循环稳定性。

Description

一种基于负极原位补锂的锂离子电池及其制备方法 技术领域
本发明属于电池技术领域,特别涉及一种基于负极原位补锂的锂离子电池及其制备方法。
背景技术
锂离子电池的正负极理论比容量有限,导致其能量密度受到限制。例如,常用的石墨负极的比容量有限,且石墨负极压实密度较低,极大限制了电池高质量和体积能量密度的获得。因此,更为高效的负极材料的研发显得尤为迫切。鉴于比容量高、反应点位低的优点,锂金属负极是高比能锂离子电池的理想选择。锂金属电池被认为是最有前景的下一代高能量密度存储设备之一,它直接使用金属锂作为负极,具有高的理论比容量(3861 mAh/g,是石墨的10.4倍),以及最低的电极电势(-3.04 V vs. SHE)。但是,为实现锂金属电池较好的循环性能,往往需要使用过量的锂金属作为负极(厚度大于250μm),通常在N/P比超过50的情况下,才能实现数百次的循环寿命。因此,高N/P比使得锂金属电池相对于传统锂离子电池实际能量密度的提升十分有限。无负极锂金属电池是一种更为理想的选择,其负极没有任何活性材料(如石墨、Li、Si、Sn),而只采用导电集流体(如铜箔)作为负极,正极则是常见的含锂材料(如磷酸铁锂、三元正极、钴酸锂等)。与锂金属电池相比,无负极锂金属电池由于负极直接采用导电集流体(如铜箔)而非超高化学活性的金属锂,给电池组装和安全性带来了极大的便利和保障。无负极锂金属电池的工作原理与传统锂离子电池不同,在充电时锂离子在负极导电集流体表面与电子结合,发生锂的沉积行为;在放电过程中,沉积在负极导电集流体的锂金属发生剥离,通过电解液重新回到正极中。然而,由于锂金属反应活性高,容易与电解液发生副反应,从而导致锂金属的不可逆损耗;同时,由于锂的沉积/剥离过程造成锂金属负极发生较大的体积变化,导致传统电解液体系下SEI膜的反复形成与破坏,消耗大量的锂离子;此外,锂的非均匀沉积/剥离过程容易诱导锂枝晶的形成,枝晶的进一步生长会造成与集流体失去电连接,形成死锂。这些行为都会导致循环稳定性差,电池快速失效。
针对负极侧由于界面副反应和“枝晶”问题导致电池循环稳定性差的问题,国内外研究团队对其失效机理进行了研究,并从电池的各主要组成部件入手,提出了不同改进策略,包括电解质的优化设计、正极改性、负极改性等手段,以提升无负极锂金属电池的库伦效率和循环性能。例如,在电解质优化设计方面,通过在电解液中添加含铟、锡和铋等盐作为添加剂,在负极表面形成含金属组分的SEI膜,这些金属通过形成合金的方式储锂,提升了锂金属电池/无负极电池的循环稳定性(专利CN112670574A)。在负极改性方面,通过对负极集流体进行表面氧化处理生成Cu(OH) 2,进而退火处理得到具有亲锂纳米氧化亚铜表面层的铜箔,有助于形成稳定的SEI膜,可促进锂的均匀沉积,抑制枝晶生长,提升电池的性能(专利CN115064700A)。另外,在正极活性物质中添加富锂材料,利用其不可逆脱锂容量高的特点,来弥补后续循环过程中负极侧的锂的不可逆损失,能够延长电池循环寿命(专利CN114284567A)。
技术问题
然而,上述手段都存在着各自的局限。例如,添加相对于锂有更高电极电位且含有铟、锡和铋等金属的盐作为添加剂,通过其在负极形成合金的方式能够实现储锂,但负极的体积膨胀相对常规无负极锂金属电池更加明显,导致循环稳定性不足。对负极集流体表面进行改性虽然提升了负极锂的沉积/剥离可逆性,但工艺繁琐,不利于规模化应用,且电池工作过程中仍需不断牺牲一部分的活性锂形成界面SEI膜,当锂金属消耗到一定程度时,电池就会失效。正极添加富锂材料虽然能达到补锂的效果,但往往与正极的生产工艺难以有效兼容,且补锂效果有限。
技术解决方案
本发明旨在至少解决上述现有技术中存在的技术问题之一。为此,本发明提出一种基于负极原位补锂的锂离子电池,其内部的电解液能为锂离子电池体系提供额外的活性锂,以减缓电池的衰减,提升电池的循环稳定性。
本发明的第一方面提供一种基于负极原位补锂的锂离子电池,所述基于负极原位补锂的锂离子电池包括正极、负极以及介于所述正极和所述负极之间的隔膜和电解液;所述电解液包括锂盐和负极补锂添加剂;所述负极补锂添加剂在充电电压为4V以上的条件下,分解产生自由基或带正电的官能团;所述自由基或带正电的官能团与所述锂盐中的阴离子结合。
本发明所述的自由基是指氢自由基、烷基自由基、烷氧自由基等;官能团是指以碳或氮为中心的带正电离子。本发明所述自由基或带正电的官能团与所述锂盐中的阴离子结合包括两种情况:一是带正电的官能团与阴离子结合,对阴离子没有造成破坏,如CH 3H 2C +与FSI -阴离子结合;二是自由基与阴离子发生反应消耗阴离子,如氢自由基与六氟磷酸根反应,生成HF和PF 5,从而消耗阴离子。
本发明的主要发明构思在于:本领域技术人员知晓,无论是充、放电过程还是电池静置过程,电解液体系内部必须保证电荷中性。例如,如果在消耗锂阳离子的负极发生耗电子反应,那么正极就要被迫插入额外的阴离子以进行电荷补偿,确保电解质中的电荷中性。根据这一性质,如果在充电过程中,电解液中的溶剂或添加剂发生分解,进一步与锂盐中的阴离子结合或发生反应消耗阴离子,那么为了保证电极之间的电子电荷中性,此时多余的阳离子(也就是锂离子)就会在负极集流体表面发生沉积,或补偿负极侧由于形成SEI膜而消耗的那一部分锂。本发明通过添加在高压(4V以上)条件下容易分解的负极补锂添加剂,该负极补锂添加剂在充电过程中分解产生自由基或带正电的官能团,与锂盐的阴离子结合或发生反应消耗阴离子,使得电解液中的部分锂离子转变为活性锂离子,从而在负极侧沉积或补充负极侧在形成SEI膜过程中消耗的一部分锂。这样既保证了稳定SEI膜的形成,又对负极进行了一个锂的原位补充,实现无负极锂金属电池在更长的时间能稳定循环而不失效。相比于以往的改性手段,本发明的负极原位补锂技术只需要对电解液组分进行调控,且能够通过电解液电荷中性的特点,提供大量的活性锂,以实现无负极锂金属电池的长循环性能。此外,本发明的电解液同样适用于基于石墨负极、硅碳负极、合金化负极等其他锂离子电池体系,通过有效补充活性锂离子在负极侧形成SEI过程中的不可逆损耗,提升电池的循环寿命。
本发明负极原位补锂的工作机理如下:在电池充电的过程中,当充到一定电压(4V以上)时,电解液中的负极补锂添加剂首先分解产生自由基或带正电的官能团,反应消耗锂盐中的阴离子或与阴离子结合;由于电解液需要保持电中性,因此电解液中的部分锂离子将转变为活性锂离子在负极侧沉积或补充负极侧在形成SEI膜过程中消耗的一部分锂。根据不同电解液体系消耗锂的程度不同,可以改变负极补锂添加剂的浓度或种类达到不同程度的补锂效果;由于不同正极材料充放电平台不同,对于充放电平台低的体系,可以选择在前几圈先充至高压(4V以上),让负极补锂添加剂分解,达到一个补充锂的效果后,再在合适的电压区间进行充放电,本发明负极原位补锂的手段能够有效减缓电池的衰减,延长电池失效时间。
优选地,所述负极补锂添加剂选自酯类化合物、醚类化合物、烯烃类化合物、含锂化合物中的一种或多种。本发明所述酯类化合物是指酸(羧酸或无机含氧酸)与醇起反应生成的一类有机化合物,如碳酸亚乙烯酯、碳酸乙烯亚乙酯、乙酸乙烯酯等;醚类化合物是指包含醚键的化合物,如乙二醇二甲醚、乙二醇苯醚、乙二醇二苯醚、苯硫醚等;烯烃类化合物是指含有C=C键(碳碳双键)的碳氢化合物,如1,2-二氯乙氧基乙烷、1,3-二氧环戊烷、4-甲基-1,3-二氧环戊烷等。
优选地,所述负极补锂添加剂包括碳酸亚乙烯酯、碳酸乙烯亚乙酯、乙酸乙烯酯、三甲基乙酸乙烯酯、二氟磷酸锂、二氟草酸硼酸锂、乙二醇二甲醚、乙二醇苯醚、乙二醇二苯醚、苯硫醚、叔丁基苯醚、氯甲基苯硫醚、环氧丙基甲基醚、四氢呋喃、2,3-二氯四氢呋喃、四氢呋喃氯、双(2-氯乙氧基)甲烷、乙基丙基醚、甲基丁基醚、二氯甲基丁醚、甲基丙基硫醚、甲基丙醚、丁基苯基醚、1,2-二氯乙氧基乙烷、氯甲基异丙基醚、2-氟苯基烯丙基醚、1-氯甲基乙基醚、2-氯乙基甲基醚、2-溴乙基甲基醚、2-氯乙基氯甲基醚、2,2,2-三氯乙基氯甲基醚、2-乙氧基氯乙烷、2-氯-1,1,2-三氟乙基甲醚、2-氯-1,1,2-三氟乙基乙醚、双(2,2,2-三氟乙基)醚、2-甲基四氢呋喃、1,3-二氧环戊烷、4-甲基二苯基醚、4-甲基-1,3-二氧环戊烷、二乙二醇二甲醚、二乙二醇二丁醚、四乙二醇二甲醚、二丙二醇二甲醚、1,2-二甲氧丙烷、三乙二醇二甲醚中的一种或多种。
优选地,所述负极补锂添加剂在所述电解液中的质量百分含量为0.1-10%。
优选地,所述负极补锂添加剂在所述电解液中的质量百分含量为1-5%。
优选地,所述锂盐包括六氟磷酸锂、双氟磺酰亚胺锂、四氟硼酸锂、硫酸锂、硝酸锂、三氟甲磺酸锂、双(三氟甲基磺酰基)亚胺锂、高氯酸锂中的一种或多种。
优选地,所述锂盐在所述电解液中的浓度为0.1-10mol/L。
优选地,所述锂盐在所述电解液中的浓度为1-5mol/L。
优选地,所述电解液还包括有机溶剂,所述有机溶剂选自酯类化合物、砜类化合物、醚类化合物、腈类化合物、羧酸酯类化合物中的一种或多种。本发明所述腈类化合物是指含有烃基和氰基的碳原子连接而成的有机化合物,如丁二腈、己二腈等。
优选地,所述有机溶剂包括碳酸丙烯酯、碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯、碳酸甲乙酯、甲酸甲酯、乙酸甲酯、N,N-二甲基乙酰胺、氟代碳酸乙烯酯、丙酸甲酯、丙酸乙酯、乙酸乙酯、γ-丁内酯、四氢呋喃、2-甲基四氢呋喃、1,3-二氧环戊烷、4-甲基-1,3-二氧环戊烷、二丙二醇二甲醚、1,2-二甲氧丙烷、三乙二醇二甲醚、二甲基砜、环丁砜、二甲醚、亚硫酸乙烯酯、亚硫酸丙烯脂、亚硫酸二甲脂、亚硫酸二乙脂、12-冠醚-4中的一种或多种。
优选地,所述电解液还包括电解液添加剂,所述电解液添加剂选自酯类化合物、砜类化合物、醚类化合物、腈类化合物、烯烃类化合物中的一种或多种。
优选地,所述电解液添加剂包括氟代碳酸乙烯酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯、1,3-丙磺酸内酯、1,4-丁磺酸内酯、硫酸乙烯酯、硫酸丙烯酯、硫酸亚乙酯、亚硫酸乙烯酯、亚硫酸丙烯酯、二甲基亚硫酸酯、二乙基亚硫酸酯、亚硫酸亚乙酯、氯代甲酸甲脂、三(三甲基硅烷)磷酸酯中的一种或多种。
优选地,所述负极采用负极集流体,所述负极集流体的材料选自金属铜箔、镍箔、钛箔、镍网、泡沫铜板、多孔铜骨架、导电碳骨架、碳纳米纤维支架或介孔碳纳米纤维。
优选地,所述负极集流体为经过表面修饰或三维集流体设计的负极集流体。所述表面修饰包括但不限于在所述负极集流体的表面涂覆聚合物涂层或快离子导体层;或在电池组装前,在所述负极集流体的表面构筑人造SEI膜。所述三维集流体设计包括但不限于对所述负极集流体如铜箔、碳基板、多孔泡沫铜板及聚合物基板进行三维结构化等。
优选地,所述负极集流体的表面涂覆有负极活性材料。所述负极活性材料包括石墨、活性炭、硬碳、钛酸锂、石墨烯、碳纳米管、硅碳、金属氧化物、铝、锡、铋、锑中的一种或多种。所述金属氧化物包括氧化锰、氧化锡、氧化镍中的一种或多种。
优选地,所述正极包括正极集流体,所述正极集流体的材料选自铝、锡、铜、铁、镍、钛、镁、锌中的一种或多种。
优选地,所述正极集流体的表面涂覆有正极活性材料,所述正极活性材料包括钴酸锂、磷酸铁锂、三元材料、锰酸锂、镍锰酸锂、天然石墨、膨胀石墨、导电炭黑、石墨烯、碳纳米管、活性碳纤维、碳分子筛中的一种或多种。
优选地,所述隔膜的材料选自玻璃纤维、聚乙烯、聚丙烯或聚丙烯/聚乙烯/聚丙烯。
优选地,所述基于负极原位补锂的锂离子电池为无负极锂金属电池。
本发明的第二方面提供本发明所述基于负极原位补锂的锂离子电池的制备方法,包括如下步骤:
将所述正极、所述负极、所述隔膜和所述电解液进行组装,得到所述基于负极原位补锂的锂离子电池。
本发明的第三方面提供一种电解液在锂离子电池负极补锂中的应用,所述电解液包括锂盐和负极补锂添加剂;所述负极补锂添加剂在充电电压为4V以上的条件下,分解产生自由基或带正电的官能团,所述自由基或带正电的官能团与所述锂盐中的阴离子结合。
有益效果
相对于现有技术,本发明的有益效果如下:
(1)本发明基于负极原位补锂的锂离子电池通过在电解液中添加负极补锂添加剂,该负极补锂添加剂在充电电压为4V以上的条件下,分解产生自由基或带正电的官能团,能够发生反应消耗阴离子或与锂盐中的阴离子结合,使电解液中的部分锂离子转变为活性锂离子,活性锂离子在负极侧沉积或补充负极侧在形成SEI膜过程中消耗的一部分锂,由此达到负极原位补锂的效果,进而提高电池的循环稳定性;本发明基于负极原位补锂的无负极锂金属电池,经过50圈的循环,容量保持率可达78.5%。
(2)本发明基于负极原位补锂的锂离子电池中的电解液与现有电池工艺具有良好的兼容性,可适用于不同类型的电池体系;此外,可以根据不同的电解液体系选择不同的负极补锂添加剂、改变负极补锂添加剂的浓度或种类来实现不同的补锂效果,具有一定的可控性。
附图说明
图1是实施例83和对比例2的双离子电池在室温下,0.2C倍率下的首圈充放电三电极测试曲线图。
图2是实施例83和对比例2在室温下,1C倍率下的循环性能曲线图。
本发明的最佳实施方式
为了让本领域技术人员更加清楚明白本发明所述技术方案,现列举以下实施例进行说明。需要指出的是,以下实施例对本发明要求的保护范围不构成限制作用。
基于无负极锂金属电池
实施例1
一种无负极锂金属电池的制备方法
电解液①的制备:电解液由有机溶剂、锂盐和高压易分解的负极补锂添加剂组成,有机溶剂为氟代碳酸乙烯酯,锂盐为双氟磺酰亚胺锂,锂盐在电解液中的摩尔浓度为5mol/L,负极补锂添加剂为乙二醇二甲醚,负极补锂添加剂在电解液中的质量分数为1wt.%。
正极①的制备:以磷酸铁锂(LFP)为正极材料,炭黑为导电剂,聚偏氟乙烯(PVDF)为粘结剂,将三者按照比例92%、5%、3%的比例在N-甲基吡咯烷酮(NMP)中混合均匀,涂覆在铝箔上,烘干后裁剪成10mm的圆片,真空干燥后制得正极极片。
负极①的处理:将铜箔浸泡在1mol/L的盐酸溶液中10min,取出后分别用去离子水和丙酮冲洗,真空干燥后转移至手套箱内,得到负极极片。
无负极锂金属电池的组装:以上述正极极片、负极极片为正极和负极,以玻璃纤维为隔膜,采用上述制备的电解液①,组装成CR2032纽扣式电池。
实施例2
一种无负极锂金属电池的制备方法
电解液②的制备:电解液由有机溶剂、锂盐和高压易分解的负极补锂添加剂组成,有机溶剂为氟代碳酸乙烯酯,锂盐为双氟磺酰亚胺锂,锂盐在电解液中的摩尔浓度为5mol/L,负极补锂添加剂为乙二醇二甲醚,负极补锂添加剂在电解液中的质量分数为2wt.%。
无负极锂金属电池的正极的制备、负极的处理及组装方法与实施例1一样,区别仅在于在无负极锂金属电池的组装中,采用电解液②进行组装。
实施例3
一种无负极锂金属电池的制备方法
电解液③的制备:电解液由有机溶剂、锂盐和高压易分解的负极补锂添加剂组成,有机溶剂为氟代碳酸乙烯酯,锂盐为双氟磺酰亚胺锂,锂盐在电解液中的摩尔浓度为5mol/L,负极补锂添加剂为乙二醇二甲醚,负极补锂添加剂在电解液中的质量分数为5wt.%。
无负极锂金属电池的正极的制备、负极的处理及组装方法与实施例1一样,区别仅在于在无负极锂金属电池的组装中,采用电解液③进行组装。
实施例4
一种无负极锂金属电池的制备方法
电解液④的制备:电解液由有机溶剂、锂盐、常规添加剂和高压易分解的负极补锂添加剂组成,有机溶剂为碳酸乙烯酯:碳酸二乙酯(1:1,v:v),锂盐为六氟磷酸锂,锂盐在电解液中的摩尔浓度为1.0 mol/L,常规添加剂为氟代碳酸乙烯酯,质量分数为2wt.%,负极补锂添加剂为乙二醇二甲醚,负极补锂添加剂在电解液中的质量分数为2wt.%。
正极②的制备:以锰酸锂为正极材料,炭黑为导电剂,聚偏氟乙烯(PVDF)为粘结剂,将三者按照比例8:1:1的比例在N-甲基吡咯烷酮(NMP)中混合均匀,涂覆在铝箔上,烘干后裁剪成10mm的圆片,真空干燥后制得正极极片。
无负极锂金属电池的负极的处理及组装方法与实施例1一样,区别在于在无负极锂金属电池的组装中,采用正极②、电解液④进行组装。
实施例5
一种无负极锂金属电池的制备方法
电解液⑤的制备:电解液由有机溶剂、锂盐、常规添加剂和高压易分解的负极补锂添加剂组成,有机溶剂为碳酸乙烯酯:碳酸二乙酯(1:1,v:v),锂盐为六氟磷酸锂,锂盐在电解液中的摩尔浓度为1 mol/L,常规添加剂为碳酸亚乙烯酯,质量分数为2wt.%,负极补锂添加剂为乙二醇二甲醚,负极补锂添加剂在电解液中的质量分数为2wt.%。
正极③的制备:以NCM523为正极材料,炭黑为导电剂,聚偏氟乙烯(PVDF)为粘结剂,将三者按照比例8:1:1的比例在N-甲基吡咯烷酮(NMP)中混合均匀,涂覆在铝箔上,烘干后裁剪成10mm的圆片,真空干燥后制得正极极片。
无负极锂金属电池的负极的处理及组装方法与实施例1一样,区别在于在无负极锂金属电池的组装中,采用正极③、电解液⑤进行组装。
实施例6
一种无负极锂金属电池的制备方法
电解液⑥的制备:电解液由有机溶剂、锂盐、常规添加剂和高压易分解的负极补锂添加剂组成,有机溶剂为氟代碳酸乙烯酯:碳酸甲乙酯(3:7,v:v),锂盐为六氟磷酸锂,锂盐在电解液中的摩尔浓度为1 mol/L,常规添加剂为碳酸亚乙烯酯,质量分数为2wt.%,负极补锂添加剂为乙二醇二甲醚,负极补锂添加剂在电解液中的质量分数为2wt.%。
正极④的制备:以NCM811为正极材料,炭黑为导电剂,聚偏氟乙烯(PVDF)为粘结剂,将三者按照比例8:1:1的比例在N-甲基吡咯烷酮(NMP)中混合均匀,涂覆在铝箔上,烘干后裁剪成10mm的圆片,真空干燥后制得正极极片。
无负极锂金属电池的负极的处理及组装方法与实施例1一样,区别在于在无负极锂金属电池的组装中,采用正极④、电解液⑥进行组装。
实施例7
一种无负极锂金属电池的制备方法
电解液⑦的制备:电解液由有机溶剂、锂盐和高压易分解的负极补锂添加剂组成,有机溶剂为氟代碳酸乙烯酯:2,2,2-三氟乙醚(2:1,v:v),锂盐为双三氟甲磺酰亚胺锂(LiTFSI),锂盐在电解液中的摩尔浓度为2 mol/L,负极补锂添加剂为二氟磷酸锂,负极补锂添加剂在电解液中的质量分数为2wt.%。
无负极锂金属电池的负极的处理及组装方法与实施例1一样,正极的制备与实施例6相同,区别在于在无负极锂金属电池的组装中,采用正极④、电解液⑦进行组装。
本发明的实施方式
对比例1
一种无负极锂金属电池的制备方法
电解液⑧的制备:由有机溶剂、锂盐组成,有机溶剂为氟代碳酸乙烯酯,锂盐为双氟磺酰亚胺锂,锂盐在电解液中的摩尔浓度为5mol/L。
无负极锂金属电池的正极的制备、负极的处理及组装方法与实施例1一样,区别仅在于在无负极锂金属电池的组装中,采用电解液⑧进行组装。
测试例1
采用新威测试系统对实施例1-7和对比例1组装的无负极锂金属电池分别进行电化学性能测试。
测试方法:
在常温下,首先以0.2C的倍率、3-5V充放电电压范围对电池进行前五圈的充放电(充电截止电压高于负极补锂添加剂的分解电压),之后以0.2C的恒定电流充放电,充放电电压范围为2.5-4.2V。测试结果如表1所示:
表1 实施例1-7和对比例1组装的电池的性能参数表
组别 放电比容量(mAh/g) 首效(%) 循环50圈容量保持率(%)
实施例1 142.9 73.5 63.1
实施例2 144.5 71.2 72.5
实施例3 143.2 74.6 69.8
实施例4 132.4 69.3 58.2
实施例5 104.6 84.5 73.1
实施例6 185.7 75.1 71.9
实施例7 178.3 56.7 68.6
对比例1 140.1 80.0 50.7
由表1可以看出,由实施例1-3和对比例1可得,本发明通过在电解液中添加高压易分解的负极补锂添加剂,通过消耗电解液中的阴离子为电池体系提供额外的活性锂,以减缓电池的衰减,提高电池循环稳定性。本发明实施例1-7由于加入了负极补锂添加剂,使无负极锂金属电池的循环性能得到了有效提升,经过50圈的循环,容量保持率约为72%,而采用对比例1组装的无负极锂金属电池经过50圈循环后容量衰减迅速,容量保持率仅为51%左右,因此采用实施例1-7的负极补锂添加剂可以提高无负极锂金属电池的循环性能。
实施例8-55
实施例8-55与实施例1的区别仅在于负极补锂添加剂的种类或浓度不同,具体如表2所示,将实施例8-55所制备的无负极锂金属电池进行电化学性能测试,其测试结果如表2所示:
表2 实施例8-55组装的电池的性能参数表
实施例 负极补锂添加剂 放电比容量(mAh/g) 首效(%) 循环50圈容量保持率(%)
8 2wt.% 碳酸亚乙烯酯 154.2 44.5 47.2
9 5wt.% 碳酸亚乙烯酯 151.9 35.1 42.3
10 2wt.% 碳酸乙烯亚乙酯 155.1 39.5 43.2
11 2wt.% 乙酸乙烯酯 152.8 34.8 44.7
12 2wt.% 三甲基乙酸乙烯酯 146.2 31.2 40.9
13 2wt.% 二氟磷酸锂 135.3 70.4 55.2
14 2wt.% 四氢呋喃 137.4 78.7 53.8
15 2wt.% 二氟草酸硼酸锂 133.7 76.5 46.4
16 2wt.% 乙二醇苯醚 136.5 74.1 57.1
17 2wt.% 乙二醇二苯醚 132.9 73.6 61.6
18 2wt.% 苯硫醚 144.1 77.4 60.9
19 2wt.% 叔丁基苯醚 141.8 73.9 66.7
20 2wt.% 1,3-二氧环戊烷 144.3 76.3 62.1
21 2wt.% 氯甲基苯硫醚 145.2 72.1 64.2
22 2wt.% 环氧丙基甲基醚 146.7 76.4 64.7
23 2wt.% 2,3-二氯四氢呋喃 149.6 71.1 74.3
24 2wt.% 二丙二醇二甲醚 146.7 77.8 78.5
25 2wt.% 四氢呋喃氯 141.9 78.5 73.2
26 2wt.% 双(2-氯乙氧基)甲烷 147.1 74.2 74.3
27 2wt.% 乙基丙基醚 149.3 75.3 72.4
28 2wt.% 甲基丁基醚 128.6 66.2 43.1
29 2wt.% 二氯甲基丁醚 130.5 63.5 41.2
30 2wt.% 甲基丙基硫醚 130.2 68.4 39.9
31 2wt.% 甲基丙醚 128.7 62.1 40.2
32 2wt.% 丁基苯基醚 129.2 61.7 41.1
33 2wt.% 1,2-二氯乙氧基乙烷 131.3 79.1 49.6
34 2wt.% 氯甲基异丙基醚 133.1 78.4 54.8
35 2wt.% 2-氟苯基烯丙基醚 132.0 76.3 52.3
36 2wt.% 1-氯甲基乙基醚 134.4 77.9 54.3
37 2wt.% 2-氯乙基甲基醚 134.9 79.3 50.9
38 2wt.% 2-溴乙基甲基醚 138.0 76.7 57.1
39 2wt.% 2-氯乙基氯甲基醚 141.7 72.2 56.8
40 2wt.% 2,2,2-三氯乙基氯甲基醚 139.8 74.1 57.7
41 2wt.% 2-乙氧基氯乙烷 141.5 75.1 56.2
42 2wt.% 2-氯-1,1,2-三氟乙基甲醚 140.8 75.4 58.3
43 2wt.% 2-氯-1,1,2-三氟乙基乙醚 145.7 69.9 54.3
44 2wt.% 双(2,2,2-三氟乙基)醚 144.0 73.1 60.7
45 2wt.% 2-甲基四氢呋喃 143.2 72.4 60.1
46 2wt.% 1,3-二氧环戊烷 143.9 71.2 66.6
47 2wt.% 4-甲基-1,3-二氧环戊烷 145.6 71.9 57.9
48 2wt.% 4-甲基二苯基醚 138.2 67.2 52.4
49 2wt.% 二乙二醇二甲醚 135.3 67.5 53.2
50 2wt.% 二乙二醇二丁醚 137.6 68.8 49.2
51 2wt.% 四乙二醇二甲醚 139.1 65.1 49.9
52 2wt.% 1,2-二甲氧丙烷 139.5 66.2 50.3
53 5wt.% 1,2-二甲氧丙烷 140.3 67.8 55.5
54 2wt.% 三乙二醇二甲醚 138.7 69.3 56.3
55 5wt.% 三乙二醇二甲醚 139.2 70.1 52.1
由表2可知,实施例8-55选用不同的负极补锂添加剂,其中实施例24添加2wt.% 二丙二醇二甲醚表现出较好的首圈效率和容量保持率,相对于不添加负极补锂添加剂的电解液组装的电池来说,补锂效果明显。
实施例56-62
实施例56-62与实施例5的区别仅在于配制的电解液中添加的常规添加剂的种类或浓度不同,具体如表3所示,将实施例56-62所组装的电池进行电化学性能测试,其测试结果如表3所示:
表3 实施例56-62组装的电池的性能参数表
实施例 常规添加剂 放电比容量(mAh/g) 首效(%) 循环50圈容量保持率(%)
56 2wt.% 氟代碳酸乙烯酯 140.3 70.4 59.1
57 5wt.% 氟代碳酸乙烯酯 141.8 66.8 59.5
58 2wt.% 亚硫酸丙烯酯 138.5 69.7 57.2
59 2wt.% 亚硫酸乙烯酯 142.2 72.1 65.6
60 2wt.% 氯甲基乙基碳酸酯 141.6 73.6 63.9
61 2wt.% 氯乙基乙基碳酸酯 143.2 69.8 64.8
62 2wt.% 氯甲基碳酸甲酯 145.9 70.5 67.3
由表3可知,加入负极补锂添加剂后,改变常规添加剂的种类和浓度,可以保证电池既具有补锂效果,也能进一步保持电池的稳定性。
实施例63-82
实施例63-82与实施例1的区别仅在于配制的电解液中有机溶剂的种类或浓度不同,具体如表4所示,将实施例63-82所组装的电池进行电化学性能测试,其测试结果如表4所示:
表4 实施例63-82组装的电池的性能参数表
实施例 有机溶剂 放电比容量(mAh/g) 首效(%) 循环50圈容量保持率(%)
63 环丁砜 137.2 70.1 55.0
64 氟代碳酸乙烯酯:环丁砜(1:1) 148.1 67.4 58.5
65 氟代碳酸乙烯酯:环丁砜(2:1) 146.9 65.7 57.2
66 氟代碳酸乙烯酯:环丁砜(1:2) 145.3 68.3 58.3
67 氟代碳酸乙烯酯:环丁砜(3:7) 144.7 67.9 61.9
68 碳酸甲乙酯 140.5 74.2 51.4
69 氟代碳酸乙烯酯:碳酸甲乙酯(1:1) 152.4 68.9 63.2
70 氟代碳酸乙烯酯:碳酸甲乙酯(2:1) 153.1 71.5 64.5
71 氟代碳酸乙烯酯:碳酸甲乙酯(1:2) 154.6 71.9 65.4
72 氟代碳酸乙烯酯:碳酸甲乙酯(3:7) 154.3 70.6 70.3
73 碳酸二乙酯 148.4 67.4 52.8
74 氟代碳酸乙烯酯:碳酸二乙酯(1:1) 150.8 70.3 58.1
75 氟代碳酸乙烯酯:碳酸二乙酯(1:2) 149.9 69.4 59.7
76 氟代碳酸乙烯酯:碳酸二乙酯(2:1) 152.4 65.2 62.6
77 氟代碳酸乙烯酯:碳酸二乙酯(3:7) 154.3 67.5 67.9
78 碳酸二甲酯 137.8 79.3 49.0
79 氟代碳酸乙烯酯:碳酸二甲酯(1:1) 145.5 72.1 57.5
80 氟代碳酸乙烯酯:碳酸二甲酯(1:2) 143.9 70.4 62.8
81 氟代碳酸乙烯酯:碳酸二甲酯(2:1) 144.5 73.6 64.1
82 氟代碳酸乙烯酯:碳酸二甲酯(3:7) 147.8 72.1 66.9
表4中的有机溶剂之间的比例为体积比。
由表4可知,实施例63-82添加了高压易分解的负极补锂添加剂,在不同的电解液有机溶剂中都能实现一定效果的补锂,提高了电池的循环稳定性。
基于传统负极材料的锂离子/双离子电池
实施例83
一种锂的双离子电池的制备方法
电解液⑨的制备:电解液由有机溶剂、锂盐和负极补锂添加剂组成,有机溶剂为碳酸甲乙酯,锂盐为六氟磷酸锂,锂盐在电解液中的摩尔浓度为4mol/L,负极补锂添加剂为碳酸亚乙烯酯,负极补锂添加剂在电解液中的质量分数为2wt.%。
正极的制备:以膨胀石墨(EG)为正极材料,炭黑为导电剂,聚偏氟乙烯(PVDF)为粘结剂,将三者按照比例92%、5%、3%的比例在N-甲基吡咯烷酮(NMP)中混合均匀,涂覆在铝箔上,烘干后裁剪成10mm的圆片,真空干燥后制得正极极片。
负极②的制备:以石墨为负极材料,导电炭黑为导电剂,LA133为粘结剂,将三者按照比例92%、5%、3%的比例在N-甲基吡咯烷酮(NMP)中混合均匀,涂覆在铜箔上,烘干后裁剪成12mm的圆片,真空干燥后制得负极极片。
双离子电池的组装:以上述正极极片、负极极片为正极和负极,以玻璃纤维为隔膜,采用上述制备的电解液⑨,组装成CR2032纽扣式电池。
实施例84
一种基于石墨负极-磷酸铁锂正极的锂离子电池
电解液⑩的制备:电解液由有机溶剂、锂盐和负极补锂添加剂组成,有机溶剂为碳酸甲乙酯:碳酸乙烯酯:碳酸二甲酯(1:1:1,v:v:v),锂盐为六氟磷酸锂,锂盐在电解液中的摩尔浓度为1mol/L,负极补锂添加剂为碳酸亚乙烯酯,负极补锂添加剂在电解液中的质量分数为2wt.%。
锂离子电池的组装:以上述正极①、负极②为正极和负极,以玻璃纤维为隔膜,采用上述制备的电解液⑩,组装成CR2032纽扣式电池。
实施例85
一种基于石墨负极-三元正极的锂离子电池
锂离子电池的组装:以上述正极④、负极②为正极和负极,以玻璃纤维为隔膜,采用上述制备的电解液⑩,组装成CR2032纽扣式电池。
实施例86
一种基于硅碳负极-磷酸铁锂正极的锂离子电池
负极③的制备:以硅碳合金粉末为负极材料,导电炭黑为导电剂,CMC、SBR为粘结剂,将四者按照比例70%、10%、10%、10%的比例在纯水中混合均匀,涂覆在铜箔上,烘干后裁剪成12mm的圆片,真空干燥后制得负极极片。
锂离子电池的组装:以上述正极①、负极③为正极和负极,以玻璃纤维为隔膜,采用上述制备的电解液⑩,组装成CR2032纽扣式电池。
实施例87
一种基于硅碳负极-三元正极的锂离子电池
锂离子电池的组装:以上述正极④、负极③为正极和负极,以玻璃纤维为隔膜,采用上述制备的电解液⑩,组装成CR2032纽扣式电池。
对比例2
一种锂的双离子电池的制备方法
电解液⑪的制备:电解液由有机溶剂、锂盐组成,有机溶剂为碳酸甲乙酯,锂盐为六氟磷酸锂,锂盐在电解液中的摩尔浓度为4mol/L。
双离子电池正极、负极的制备及组装方法与实施例83一样,区别仅在于在锂的双离子电池的组装中,采用电解液⑪进行组装。
对比例3
一种基于石墨负极-磷酸铁锂正极的锂离子电池
电解液⑫的制备:电解液由有机溶剂、锂盐组成,有机溶剂为碳酸甲乙酯:碳酸乙烯酯:碳酸二甲酯(1:1:1,v:v:v),锂盐为六氟磷酸锂,锂盐在电解液中的摩尔浓度为1mol/L。
锂离子电池正极、负极的制备及组装方法与实施例84一样,区别仅在于在锂离子电池的组装中,采用电解液⑫进行组装。
对比例4
一种基于硅碳负极-磷酸铁锂正极的锂离子电池
电解液⑬的制备:电解液由有机溶剂、锂盐组成,有机溶剂为碳酸甲乙酯:碳酸乙烯酯:碳酸二甲酯(1:1:1,v:v:v),锂盐为六氟磷酸锂,锂盐在电解液中的摩尔浓度为1mol/L。
锂离子电池正极、负极的制备及组装方法与实施例86一样,区别仅在于锂离子电池的组装中,采用电解液⑬进行组装。
测试例2
采用新威测试系统对实施例83和对比例2组装的双离子电池分别进行电化学性能测试。
测试方法:
在常温下,以0.2C恒定电流进行首圈充放电活化,之后以1C的恒定电流充放电,充放电的电压范围为3-5V。测试结果如图1、图2所示。图1是本发明实施例83和对比例2的双离子电池在室温(约25℃)下,0.2C倍率下的首圈充放电三电极测试曲线图,其中,图1(a)是对比例2的首圈充放电三电极测试曲线图,图1(b)是实施例83的首圈充放电三电极测试曲线图。图2是本发明实施例83和对比例2在室温下,1C倍率下的循环性能曲线图。
从图1和图2可知,实施例83在添加了碳酸亚乙烯酯(VC)作为负极补锂添加剂后,首圈充放电时VC在高压分解,分解后与阴离子结合或消耗阴离子,使得电解液中的部分锂离子转变为活性锂离子在负极侧沉积,形成了稳定坚固的SEI膜,从而提高了双离子电池的循环性能。
工业实用性
测试例3
采用新威测试系统对实施例84-87和对比例3-4组装的锂离子电池分别进行电化学性能测试。
测试方法:
在常温下,首先分别以0.2C的倍率、3-4.6V充放电电压范围对实施例84、86组装的电池,以0.2C的倍率、3-4.8V充放电电压范围对实施例85、87组装的电池进行前五圈的充放电(充电截止电压高于负极补锂添加剂的分解电压),之后以0.2C的恒定电流充放电,充放电电压范围为2.5-4.2V。测试结果如表5所示:
表5实施例84-87和对比例3-4组装的电池的性能参数表
组别 放电比容量(mAh/g) 首效(%) 循环50圈容量保持率(%)
实施例84 155.7 73.6 75.5
实施例85 182.3 79.2 76.1
实施例86 158.2 78.1 78.3
实施例87 183.5 71.2 79.6
对比例3 151.9 76.3 52.4
对比例4 152.4 72.5 53.2
由表5可知,实施例84-87选用不同的负极和正极,在添加有高压易分解的负极补锂添加剂条件下,同样也能起到对负极进行原位补锂的效果,以此可以增加电池的循环稳定性和容量保持率。
以上对本发明的较佳实施方式进行了具体说明,但本发明创造并不限于所述实施例,熟悉本领域的技术人员在不违背本发明精神的前提下还可作出种种的等同变型或替换,这些等同的变型或替换均包含在本申请权利要求所限定的范围内。

Claims (13)

  1. 一种基于负极原位补锂的锂离子电池,其特征在于,所述锂离子电池包括正极、负极以及介于所述正极和所述负极之间的隔膜和电解液;所述电解液包括锂盐和负极补锂添加剂;所述负极补锂添加剂在充电电压为4V以上的条件下,分解产生自由基或带正电的官能团;所述自由基或带正电的官能团与所述锂盐中的阴离子结合。
  2. 根据权利要求1所述的基于负极原位补锂的锂离子电池,其特征在于,所述负极补锂添加剂选自酯类化合物、醚类化合物、烯烃类化合物、含锂化合物中的一种或多种。
  3. 根据权利要求2所述的基于负极原位补锂的锂离子电池,其特征在于,所述负极补锂添加剂包括碳酸亚乙烯酯、碳酸乙烯亚乙酯、乙酸乙烯酯、三甲基乙酸乙烯酯、二氟磷酸锂、二氟草酸硼酸锂、乙二醇二甲醚、乙二醇苯醚、乙二醇二苯醚、苯硫醚、叔丁基苯醚、氯甲基苯硫醚、环氧丙基甲基醚、四氢呋喃、2,3-二氯四氢呋喃、四氢呋喃氯、双(2-氯乙氧基)甲烷、乙基丙基醚、甲基丁基醚、二氯甲基丁醚、甲基丙基硫醚、甲基丙醚、丁基苯基醚、1,2-二氯乙氧基乙烷、氯甲基异丙基醚、2-氟苯基烯丙基醚、1-氯甲基乙基醚、2-氯乙基甲基醚、2-溴乙基甲基醚、2-氯乙基氯甲基醚、2,2,2-三氯乙基氯甲基醚、2-乙氧基氯乙烷、2-氯-1,1,2-三氟乙基甲醚、2-氯-1,1,2-三氟乙基乙醚、双(2,2,2-三氟乙基)醚、2-甲基四氢呋喃、1,3-二氧环戊烷、4-甲基二苯基醚、4-甲基-1,3-二氧环戊烷、二乙二醇二甲醚、二乙二醇二丁醚、四乙二醇二甲醚、二丙二醇二甲醚、1,2-二甲氧丙烷、三乙二醇二甲醚中的一种或多种。
  4. 根据权利要求1所述的基于负极原位补锂的锂离子电池,其特征在于,所述负极补锂添加剂在所述电解液中的质量百分含量为0.1-10%。
  5. 根据权利要求4所述的基于负极原位补锂的锂离子电池,其特征在于,所述负极补锂添加剂在所述电解液中的质量百分含量为1-5%。
  6. 根据权利要求1所述的基于负极原位补锂的锂离子电池,其特征在于,所述锂盐包括六氟磷酸锂、双氟磺酰亚胺锂、四氟硼酸锂、硫酸锂、硝酸锂、三氟甲磺酸锂、双(三氟甲基磺酰基)亚胺锂、高氯酸锂中的一种或多种。
  7. 根据权利要求1所述的基于负极原位补锂的锂离子电池,其特征在于,所述锂盐在所述电解液中的浓度为0.1-10mol/L。
  8. 根据权利要求7所述的基于负极原位补锂的锂离子电池,其特征在于,所述锂盐在所述电解液中的浓度为1-5mol/L。
  9. 根据权利要求1所述的基于负极原位补锂的锂离子电池,其特征在于,所述电解液还包括有机溶剂,所述有机溶剂选自酯类化合物、砜类化合物、醚类化合物、腈类化合物、羧酸酯类化合物中的一种或多种。
  10. 根据权利要求1所述的基于负极原位补锂的锂离子电池,其特征在于,所述电解液还包括电解液添加剂,所述电解液添加剂包括氟代碳酸乙烯酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯、1,3-丙磺酸内酯、1,4-丁磺酸内酯、硫酸乙烯酯、硫酸丙烯酯、硫酸亚乙酯、亚硫酸乙烯酯、亚硫酸丙烯酯、二甲基亚硫酸酯、二乙基亚硫酸酯、亚硫酸亚乙酯、氯代甲酸甲脂、三(三甲基硅烷)磷酸酯中的一种或多种。
  11. 根据权利要求1所述的基于负极原位补锂的锂离子电池,其特征在于,所述负极采用负极集流体,所述负极集流体的材料选自金属铜箔、镍箔、钛箔、镍网、泡沫铜板、多孔铜骨架、导电碳骨架、碳纳米纤维支架或介孔碳纳米纤维。
  12. 权利要求1-11任一项所述的基于负极原位补锂的锂离子电池的制备方法,其特征在于,包括如下步骤:
    将所述正极、所述负极、所述隔膜和所述电解液进行组装,得到所述基于负极原位补锂的锂离子电池。
  13. 一种电解液在锂离子电池负极补锂中的应用,其特征在于,所述电解液包括锂盐和负极补锂添加剂;所述负极补锂添加剂在充电电压为4V以上的条件下,分解产生自由基或带正电的官能团;所述自由基或带正电的官能团与所述锂盐中的阴离子结合。
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