WO2018048188A1 - Electrolyte additive and lithium secondary battery comprising same - Google Patents

Electrolyte additive and lithium secondary battery comprising same Download PDF

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Publication number
WO2018048188A1
WO2018048188A1 PCT/KR2017/009758 KR2017009758W WO2018048188A1 WO 2018048188 A1 WO2018048188 A1 WO 2018048188A1 KR 2017009758 W KR2017009758 W KR 2017009758W WO 2018048188 A1 WO2018048188 A1 WO 2018048188A1
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WIPO (PCT)
Prior art keywords
anion
additive
electrolyte solution
group
lithium
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PCT/KR2017/009758
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French (fr)
Korean (ko)
Inventor
김재윤
임형규
이종현
한지성
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솔브레인 주식회사
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Priority claimed from KR1020160174854A external-priority patent/KR20180027987A/en
Priority claimed from KR1020170081412A external-priority patent/KR101980315B1/en
Application filed by 솔브레인 주식회사 filed Critical 솔브레인 주식회사
Priority to JP2019513038A priority Critical patent/JP2019526914A/en
Priority to EP17849072.8A priority patent/EP3512024A4/en
Priority to CN201780055004.1A priority patent/CN109690864A/en
Publication of WO2018048188A1 publication Critical patent/WO2018048188A1/en
Priority to US16/293,685 priority patent/US11024881B2/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to an electrolyte additive and a lithium secondary battery including the same in a nonaqueous electrolyte.
  • Lithium secondary batteries are the batteries that can best meet these demands, and research on these is being actively conducted.
  • a lithium secondary battery is a battery composed of a positive electrode, a negative electrode, and an electrolyte solution and a separator that provides a movement path of lithium ions between the positive electrode and the negative electrode, and is used for oxidation and reduction reactions when lithium ions are occluded and discharged from the positive electrode and the negative electrode. Thereby generating electrical energy.
  • the average discharge voltage of the lithium secondary battery is about 3.6 to 3.7 V, which is one of the advantages of higher discharge voltage than other alkaline batteries, nickel-cadmium batteries, and the like.
  • an electrochemically stable electrolyte composition is required in the charge and discharge voltage range of 0 to 4.2V.
  • lithium ions derived from the positive electrode active material such as lithium metal oxide are moved to the negative electrode active material such as graphite and inserted into the interlayer of the negative electrode active material.
  • the electrolyte and the carbon constituting the negative electrode active material react on the surface of the negative electrode active material such as graphite to generate a compound such as Li 2 CO 3 , Li 2 O, or LiOH.
  • SEI Solid Electrolyte Interface
  • the SEI membrane acts as an ion tunnel, passing only lithium ions.
  • the SEI membrane is an effect of this ion tunnel, which prevents the breakdown of the negative electrode structure by intercalation of organic solvent molecules having a large molecular weight moving with lithium ions in the electrolyte between the layers of the negative electrode active material. Therefore, by preventing contact between the electrolyte solution and the negative electrode active material, decomposition of the electrolyte solution does not occur, and the amount of lithium ions in the electrolyte solution is reversibly maintained to maintain stable charge and discharge.
  • the problem to be solved of the present invention is to provide a novel electrolyte additive.
  • a lithium secondary battery comprising a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator interposed between the positive electrode and the negative electrode and a non-aqueous electrolyte containing the electrolyte additive of the present invention To provide.
  • the present invention provides an electrolyte additive comprising a salt of a nitrogen atom-containing compound-derived anion and Cs + or Rb + .
  • the present invention provides an electrolyte additive which further comprises lithium difluoro bisoxalato phosphate in the electrolyte additive.
  • the present invention provides a non-aqueous electrolyte comprising a lithium salt, a non-aqueous organic solvent and the electrolyte additive.
  • the present invention also provides a lithium secondary battery including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator interposed between the positive electrode and the negative electrode and the non-aqueous electrolyte.
  • the secondary battery formed by including the electrolyte additive according to an embodiment of the present invention is excellent in high temperature and low temperature life characteristics, high temperature storage characteristics and thickness change rate.
  • a secondary battery formed by including a compound containing a salt of a nitrogen atom-containing compound-derived anion and Cs + or Rb + and an electrolyte additive comprising lithium difluoro bisoxalato phosphate according to another embodiment of the present invention Excellent high temperature output characteristics.
  • the novel electrolyte additive according to one embodiment of the present invention may include a salt of a nitrogen atom-containing compound-derived anion and Cs + or Rb + .
  • the nitrogen atom-containing compound-derived anion may include one or more selected from the group consisting of an amide anion, an imide anion, a nitrile anion, a nitrite anion, and a nitrate anion.
  • the amide-based anion is one selected from the group consisting of dimethylformamide anion, dimethylacetamide anion, diethylformamide anion, diethylacetamide anion, methylethylformamide anion, and methylethylacetamide anion. It may be included above.
  • imide-based anion may be represented by Formula 1 below.
  • R 1 and R 2 are each a fluoro group or a fluoroalkyl group having 1 to 4 carbon atoms, or R 1 and R 2 are connected to each other to form a fluoro cycloalkylene ring having 1 to 4 carbon atoms You may also do it.
  • the nitrile anions include acetonitrile anion, propionitrile anion, butyronitrile anion, valeronitrile anion, caprylonitrile anion, heptanenitrile anion, cyclopentane carbonitrile anion, cyclohexane carbonitrile anion, and 2-fluorobenzo Nitrile anion, 4-fluorobenzonitrile anion, difluorobenzonitrile anion, trifluorobenzonitrile anion, phenylacetonitrile anion, 2-fluorophenylacetonitrile anion, and 4-fluorophenylacetonitrile anion It may be one containing at least one selected from the group.
  • the compound represented by Chemical Formula 1 may include one or more selected from the group consisting of the following Chemical Formulas 2 to 6.
  • the electrolyte additive is cesium bis (trifluoromethanesulfonyl) imide, cesium nitrate, rubidium bis (trifluoromethanesulfonyl) imide, rubidium nitrate and cesium bis ( It may be one containing one or more selected from the group consisting of fluorosulfonyl) imide.
  • the present invention can provide a non-aqueous electrolyte solution containing a lithium salt, a non-aqueous organic solvent and the electrolyte additive.
  • the additive may form a film on the surface of the positive electrode and the negative electrode in the electrolyte.
  • an oxidation reaction is performed on the surface of the cathode and a reduction reaction is performed on the surface of the anode.
  • the additive according to an embodiment of the present invention may form a film on the surfaces of the cathode and the anode to effectively control the dissolution of lithium ions generated from the anode, and may prevent a phenomenon in which the anode is decomposed.
  • the film formed by the additive on the surface of the cathode is partially decomposed through the reduction reaction during charging and discharging, but the decomposed additive may move back to the surface of the anode and form a film on the surface of the anode again through an oxidation reaction. have. Therefore, even after repeated charging and discharging several times, the additive can maintain the film on the surface of the positive electrode, thereby effectively preventing excessive elution of lithium ions at the positive electrode.
  • Cs + or Rb + of the additive according to an embodiment of the present invention is an ion of an alkali element, which is due to the chemical properties of Li + present in the positive electrode and the negative electrode. It is assumed. Therefore, the secondary battery according to an embodiment of the present invention does not collapse the structure even if the positive electrode is repeatedly charged and discharged, it can be effectively maintained to improve the high temperature and low temperature life characteristics of the secondary battery.
  • the additive according to the embodiment of the present invention may improve the safety of the battery by reducing side reactions and generated contact surfaces between the positive electrode and the electrolyte. Due to the characteristics of the high reaction potential and little change in the reaction potential with the progress of the cycle, it is possible to prevent the degradation of the battery due to the conventional additive decomposition and sudden change of the reaction potential. Furthermore, the additive forms a stable film through an oxidation reaction at the anode, thereby preventing decomposition of the anode and suppressing elution, thereby more stably protecting the anode under a high voltage environment.
  • the additive may further include a heterogeneous additive to improve the stability of the lithium secondary battery or the output.
  • This may further include lithium difluoro bisoxalato phosphate in an additive comprising a salt of the above-described nitrogen atom-containing compound anion and Cs + or Rb + , more specifically cesium bis (trifluoromethane One or more selected from the group consisting of sulfonyl) imide, cesium nitrate, rubidium bis (trifluoromethanesulfonyl) imide rubidium nitrate and cesium bis (fluorosulfonyl) imide and lithium difluoro bis It may be one containing oxalato phosphate.
  • Lithium difluoro bisoxalato phosphate can form a stable SEI film on the surface of the anode and cathode.
  • An additive comprising a salt of a nitrogen atom-containing compound anion and Cs + or Rb + is lithium difluoro bisoxalato phosphate.
  • the SEI film of the negative electrode and the positive electrode formed from lithium difluoro bisoxalato phosphate can be formed more uniformly, and the movement of lithium ions becomes easier according to the formation of the uniform film. Better output characteristics can be obtained.
  • the additive including the salt with Cs + or Rb + and lithium difluoro bisoxalato phosphate are preferably included in the electrolyte at a weight ratio of 1: 1 to 1: 4.
  • the content of the additive may be 0.05 to 10% by weight based on the total amount of the non-aqueous electrolyte.
  • the content of the additive may be 0.1 to 3% by weight based on the total amount of the non-aqueous electrolyte.
  • the content of the additive is less than 0.05% by weight, the effect of improving the low temperature and high temperature storage characteristics and the high temperature life characteristics of the lithium secondary battery is insignificant, and if the content of the additive exceeds 10% by weight due to excessive film formation, resistance This increasing problem can occur.
  • the lithium salt may be used a lithium salt commonly used in the art, for example LiPF 6 , LiFSI, LiAsF 6 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiBF 4 , LiSbF 6 , LiN It may include one or more selected from the group consisting of (C 2 F 5 SO 2 ) 2 , LiAlO 4 , LiAlCl 4 , LiSO 3 CF 3 , LiTFSI, LiDFOB, and LiClO 4 .
  • the lithium salt preferably has a concentration in the non-aqueous electrolyte solution of 0.01 mole / l to 2 mole / l, more preferably 0.01 mole / l to 1 mole / l.
  • organic solvents commonly used in lithium secondary battery electrolytes can be used without limitation, for example, ethers, esters, amides, linear carbonates, cyclic carbonates, phosphoric acid compounds, A nitrile compound, a fluorinated ether compound, a fluorinated aromatic compound, etc. can be used individually or in mixture of 2 or more types, respectively.
  • carbonate compounds which are typically cyclic carbonates, linear carbonates or mixtures thereof may be included.
  • cyclic carbonate compound include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene It may include one or more selected from the group consisting of carbonates, vinylene carbonates, and halides thereof.
  • linear carbonate compounds include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC) and ethylpropyl carbonate (EPC). It may include one or more selected from the group consisting of, but is not limited thereto.
  • the cyclic carbonate in the carbonate-based electrolyte solvent preferably includes propylene carbonate, ethylene carbonate, and mixtures thereof, and may be preferably used because it dissociates lithium salt in the electrolyte well because of high dielectric constant as a high-viscosity organic solvent.
  • diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, and a linear carbonene, which is a mixture thereof, with the cyclic carbonate can be more preferably used because low viscosity, low dielectric constant linear carbonate can be mixed in an appropriate ratio to make an electrolyte having high electrical conductivity.
  • ester in the electrolyte solvent is methyl acetate, ethyl acetate, propyl acetate, ethyl propionate (EP), propyl propionate, methyl propionate (MP), ⁇ -butyrolactone, ⁇ -valerolactone , ⁇ -caprolactone, ⁇ -valerolactone and ⁇ -caprolactone, and may include one or more selected from among them, particularly low viscosity ethyl propionate (EP), propyl propionate, It is preferred to include methyl propionate (MP) and mixtures thereof.
  • the phosphoric acid solvent and the mononitrile solvent may be substituted with a fluorine atom (F).
  • F fluorine atom
  • the solvent is substituted with a halogen element, the flame retardancy is further increased, but when the solvent is substituted with Cl, Br, or I, the reactivity of the solvent increases together, which is not preferable as an electrolyte solution.
  • non-limiting examples of the phosphate compound include trimethylphosphine oxide, triethylphosphine oxide, tripropylphosphine oxide, triphenylphosphine oxide, diethyl methylphosphonate, di Methyl methylphosphonate, diphenyl methylphosphonate, bis (2,2,2-trifluoroethyl) methylphosphonate, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, ethyl methyl phenyl phosphate and the like.
  • These phosphoric acid solvents may be used alone or in combination of two or more thereof.
  • non-limiting examples of the nitrile-based compound include acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzo Nitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile and the like.
  • These nitrile solvents can be used individually or in mixture of 2 or more types.
  • fluorinated ether compound examples include bis-, 2,2-trifluoroethyl ether, n-butyl 1,1,2,2-tetrafluoroethyl ether, 2,2,3, 3,3-pentafluoropropyl methyl ether, 2,2,3,3,3-pentafluoropropyl 1,1,2,2-tetrafluoroethyl ether, 1,1,2,2-tetrafluoroethyl Methyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, trifluoroethyl dodecafluorohexyl ether, and the like.
  • fluorinated ether solvents may be used alone or in combination of two or more thereof.
  • Non-limiting examples of aromatic compound solvents include halogenated benzene compounds such as chlorobenzene, chlorotoluene and fluorobenzene, tert-butyl benzene, tert-pentyl benzene, cyclohexyl benzene, hydrogen biphenyl and hydrogenated terphenyl.
  • Alkylated aromatic compounds such as these, are mentioned.
  • the alkyl group of the said alkylated aromatic compound may be halogenated, and the fluorinated thing is mentioned as an example. Examples of such fluorinated compounds include trifluoro methoxy benzene and the like.
  • the lithium secondary battery according to an embodiment of the present invention may include a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator interposed between the positive electrode and the negative electrode and the non-aqueous electrolyte solution.
  • the positive electrode active material can be used without limitation as long as it is a compound capable of intercalating / deintercalating lithium.
  • the positive electrode active material is a spinel lithium transition metal oxide having a thin crystal layered rock salt structure, an olivine structure, and a cubic structure having high capacity characteristics, in addition to V 2 O 5 , TiS , MoS may include one or more selected from the group consisting of. More specifically, for example, the composition may include one or more selected from the group consisting of compounds represented by Formulas 7 to 9:
  • the positive electrode active material is preferably Li [Ni 0.6 Co 0.2 Mn 0.2 ] O 2 , Li (Ni 0.5 Co 0.2 Mn 0.3 ) O 2 , Li [Ni 1/3 Co 1/3 Mn 1/3 ] O 2 , and It may include one or more selected from the group consisting of LiCoO 2 .
  • the Li [Ni a Co b Mn c ] O 2 in the positive electrode can have a synergistic effect in combination with the compound of formula (1) of the present invention.
  • the positive electrode active material of the lithium-nickel-manganese-cobalt-based oxide As the content of Ni in the transition metal increases, Li + 1 ions and Ni + 2 ions in the layered structure of the positive electrode active material change positions during charge and discharge. (cation mixing) may occur and the structure may become unstable, and thus the positive electrode active material may cause side reactions with the electrolyte, or dissolution of transition metals. Therefore, when using the electrolyte additive of the formula (1) according to an embodiment of the present invention, it is assumed that the phenomenon of the cation mixing (cation mixing) can be minimized.
  • the negative electrode active material includes amorphous carbon or crystalline carbon, specifically, carbon such as non-graphitized carbon, graphite carbon; LixFe 2 O 3 (0 ⁇ x ⁇ 1), LixWO 2 (0 ⁇ x ⁇ 1 ), SnxMe 1 - x Me ' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P , Metal complex oxides such as Si, Group 1, 2, 3 Group elements of the periodic table, halogen, 0 ⁇ x ⁇ 1, 1 ⁇ y ⁇ 3, 1 ⁇ z ⁇ 8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO 2 , PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , GeO, GeO 2 , Bi 2 O 3 , Bi 2 O 4 ,
  • the separator is a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer This may be a single or two or more laminated.
  • a porous nonwoven fabrics such as high-melting glass fibers, polyethylene terephthalate fibers, and the like may be used, but are not limited thereto.
  • the positive electrode and / or the negative electrode may be prepared by mixing and stirring a binder, a solvent, a conductive agent and a dispersant which may be commonly used as needed, to prepare a slurry, and then applying the same to a current collector and compressing the same.
  • the binder may be polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HEP), polyvinylidene fluoride (polyvinylidenefluoride), polyacrylonitrile, polymethylmethacrylate, Polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), Various kinds of binder polymers such as sulfonated EPDM, styrene butyrene rubber (SBR), fluorine rubber, various copolymers and the like may be used.
  • PVDF-co-HEP polyvinylidene fluoride-hexafluoropropylene copolymer
  • SBR styrene butyrene rubber
  • the lithium secondary battery including the additive may undergo a formation and aging process to secure the performance of the secondary battery.
  • the formation process is to activate the battery by repeatedly charging and discharging the battery after assembling the battery. Lithium ions from the lithium metal oxide used as the anode during charging are moved to the carbon electrode used as the cathode, where lithium Due to its high reactivity, it reacts with the carbon anode to form compounds such as Li 2 CO 3 , LiO, LiOH, and these form a solid electrolyte interface (SEI) film on the surface of the cathode.
  • SEI solid electrolyte interface
  • the aging process is to stabilize the battery activated as described above for a certain period of time.
  • the SEI film is formed on the surface of the cathode through the formation process, and the SEI film is generally stabilized by standing at room temperature for a certain period of time, that is, at room temperature.
  • Lithium secondary battery using a non-aqueous liquid containing an additive according to an embodiment of the present invention not only at room temperature aging process, but also at a high temperature aging process by the Cs, Rb which is the cognate element of lithium, It can be seen that there is no problem such as reduced stability or decomposition thereof.
  • the formation step is not particularly limited and may be half charged at 1.0 to 3.8V or full charge at 3.8 to 4.3V.
  • the C-RATE may be charged for 5 minutes to 1 hour at a current density of 0.1C ⁇ 2C.
  • the aging step may be carried out at room temperature or in a temperature range (high temperature) of 60 to 100 °C. If the temperature exceeds 100 ° C., there is a possibility that the packaging material may rupture or the battery may ignite due to evaporation of the electrolyte.
  • the remaining capacity SOC of the battery may be in any range from 100% when the battery is fully charged to 0% due to discharge.
  • the storage time is not particularly limited, but is preferably about 1 hour to 1 week.
  • the external shape of the lithium secondary battery according to an embodiment of the present invention is not particularly limited, but may be cylindrical, rectangular, pouch type, or coin type using a can.
  • Ethylene carbonate (EC): ethylmethyl carbonate (EMC): diethyl carbonate (DEC) 30:50:20 (volume ratio)
  • EMC ethylmethyl carbonate
  • DEC diethyl carbonate
  • NMP solvent N-methyl-2-pyrrolidone
  • the positive electrode mixture slurry was applied to a thin film of aluminum (Al), which is a positive electrode current collector having a thickness of about 20 ⁇ m, dried to prepare a positive electrode, and then subjected to roll press to prepare a positive electrode.
  • a negative electrode mixture slurry was prepared by adding carbon powder as a negative electrode active material, PVdF as a binder, and carbon black as a conductive agent at 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as a solvent.
  • the negative electrode mixture slurry was applied to a copper (Cu) thin film, which is a negative electrode current collector having a thickness of 10 ⁇ m, dried to prepare a negative electrode, and then roll-rolled to prepare a negative electrode.
  • Cu copper
  • a non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 0.7 wt% of cesium bis (trifluoromethanesulfonyl) imide was added as the additive to 0.7 wt% based on the total amount of the non-aqueous electrolyte. It was.
  • a nonaqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 1 wt% of cesium bis (trifluoromethanesulfonyl) imide was added as the additive based on the total amount of the nonaqueous electrolyte. It was.
  • a non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 3 wt% of cesium bis (trifluoromethanesulfonyl) imide was added as the additive based on the total amount of the non-aqueous electrolyte solution. It was.
  • a non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that cesium nitrate was used in an amount of 0.5% by weight instead of cesium bis (trifluoromethanesulfonyl) imide.
  • a nonaqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 0.7 wt% of cesium nitrate was used instead of cesium bis (trifluoromethanesulfonyl) imide as the additive.
  • a non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that 1.0 wt% of cesium nitrate was used instead of the cesium bis (trifluoromethanesulfonyl) imide.
  • a non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 3.0 wt% of cesium nitrate was used instead of the cesium bis (trifluoromethanesulfonyl) imide.
  • a non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 0.5 wt% of rubidium bis (trifluoromethanesulfonyl) imide was used instead of cesium bis (trifluoromethanesulfonyl) imide as the additive.
  • the battery was prepared.
  • a non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 0.5 wt% of rubidium nitrate was used instead of cesium bis (trifluoromethanesulfonyl) imide as the additive.
  • Cesium nitrate instead of cesium bis (trifluoromethanesulfonyl) imide as the additive was added 0.5% by weight based on the total amount of the non-aqueous electrolyte and 0.5% by weight of the lithium difluoro bisoxalatophosphate.
  • a nonaqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except for the above.
  • a non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the cathode active material was used as Li [Ni 1/3 Co 1/3 Mn 1/3 ] O 2 .
  • a non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the positive electrode active material was used as LiCoO 2 .
  • a nonaqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that cesium bis (trifluoromethanesulfonyl) imide additive was added at 0.03% by weight in the nonaqueous electrolyte solution.
  • Cesium bis (trifluoromethanesulfonyl) imide in the non-aqueous electrolyte A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the additive was added in an amount of 11 wt%.
  • Cesium nitrate instead of cesium bis (trifluoromethanesulfonyl) imide in the non-aqueous electrolyte A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the additive was added at 0.03% by weight.
  • Cesium nitrate instead of cesium bis (trifluoromethanesulfonyl) imide in the non-aqueous electrolyte A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the additive was added in an amount of 11 wt%.
  • the lithium secondary battery is charged at a constant current until the voltage reaches 4.20 V (vs. Li) at a high temperature (45 ° C.) at a current of 1.5 C, and then cuts off at a current of 0.05 C at a constant voltage mode while maintaining 4.20 V. (cut-off). Subsequently, discharge was performed at a constant current of 1.5 C rate (1st cycle) until the voltage reached 3.0 V (vs. Li). The same cycle was repeated up to 300 cycles.
  • the experimental results are shown in Table 1 and Table 2.
  • the lithium secondary battery was operated at room temperature (25 ° C) -low temperature (-10 ° C) -low temperature (-20 ° C) -room temperature (25 ° C) at a current of 0.5C rate until the voltage reached 4.20V (vs. Li). Constant current charge was then cut-off at a current of 0.05 C rate while maintaining 4.20 V in constant voltage mode. Subsequently, it discharged at the constant current of 0.5 C rate (1st cycle) until the voltage reached 3.0V (vs. Li) at the time of discharge. The cycle was repeated 10 times in sequence for each temperature.
  • Example 1 899.25 536.72 218.85 415.82 46.24
  • Example 2 898.16 534.12 217.5 413.17 46.00
  • Example 3 897.84 532.48 216.82 411.15 45.79
  • Example 4 896.68 529.28 214.96 405.29 45.20
  • Example 5 896.81 533.18 215.18 412.3 45.97
  • Example 6 895.18 531.84 214.79 407.17 45.48
  • Example 7 893.37 529.76 213.14 402.23 45.02
  • Example 9 890.84 527.18 208.24 405.74 45.55
  • Example 10 887.21 526.87
  • Example 1 47.5 79 166.32
  • Example 2 47.8 80.6 168.62
  • Example 3 48.4 81.9 169.21
  • Example 4 50.1 85.6 170.86
  • Example 5 48.4 84 173.55
  • Example 6 48.9 85.1 174.03
  • Example 7 49.8 87.4 175.50
  • Example 8 51.4 91.7 178.40
  • Example 9 48.1 81.1 168.61
  • Example 10 50.1 87.5 174.65
  • Example 11 47.2 78.8 166.95
  • Example 12 48.1 83.4 173.39
  • Example 13 47.9 80.8 168.68
  • Example 14 48.2 82.1 170.33
  • the first cycle was charged and discharged at 0.1C, and the subsequent cycle was charged and discharged at 0.5C.
  • the thickness change rate was compared with the electrode thickness before the first cycle after disassembling each of the lithium secondary batteries in the state of charge of the 300th cycle and measuring the electrode thickness. The results are shown in Tables 7 and 8.
  • Thickness change rate electrode thickness at 300th cycle of charge state-electrode thickness before first cycle) / electrode thickness before first cycle x 100
  • Example 1 107.24
  • Example 2 107.66
  • Example 3 108.18
  • Example 4 109.14
  • Example 5 108.53
  • Example 6 108.75
  • Example 7 109.09
  • Example 8 110.24
  • Example 9 108.19
  • Example 10 109.23
  • Example 11 108.36
  • Example 12 109.98
  • Example 13 108.96
  • Example 14 108.78
  • Example 15 113.21
  • Example 16 117.25
  • Example 17 114.12
  • Example 18 118.29
  • the secondary battery of the embodiment of the present invention is significantly superior to the secondary battery in terms of high temperature, low temperature life characteristics, high temperature storage characteristics, and thickness change rates in comparison with the comparative examples.
  • Ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) 30:50:20 (volume ratio)
  • a non-aqueous organic solvent, LiPF 6 as a lithium salt based on the total amount of the non-aqueous electrolyte solution 1.15 mole / l was added, and 0.5% by weight of cesium bis (trifluoromethanesulfonyl) imide and 1% by weight of lithium difluoro bisoxalatophosphate (weight ratio 1: 2) were added as a additive based on the total amount of the non-aqueous electrolyte solution.
  • NMP solvent N-methyl-2-pyrrolidone
  • the positive electrode mixture slurry was applied to a thin film of aluminum (Al), which is a positive electrode current collector having a thickness of about 20 ⁇ m, dried to prepare a positive electrode, and then subjected to roll press to prepare a positive electrode.
  • a negative electrode mixture slurry was prepared by adding carbon powder as a negative electrode active material, PVdF as a binder, and carbon black as a conductive agent at 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as a solvent.
  • the negative electrode mixture slurry was applied to a copper (Cu) thin film, which is a negative electrode current collector having a thickness of 10 ⁇ m, dried to prepare a negative electrode, and then roll-rolled to prepare a negative electrode.
  • Cu copper
  • the electrolyte solution additive contained 0.5 wt% cesium bis (trifluoromethanesulfonyl) imide and 0.5 wt% lithium difluoro bisoxalatophosphate (weight ratio 1: 1).
  • a nonaqueous electrolyte solution and a lithium secondary battery were prepared.
  • Example 19 Same as Example 19, except that 0.5 wt% cesium bis (trifluoromethanesulfonyl) imide and 2 wt% lithium difluoro bisoxalato phosphate (weight ratio 1: 4) were included as the electrolyte additive.
  • a nonaqueous electrolyte solution and a lithium secondary battery were prepared.
  • Example 19 Same as Example 19, except that 0.5 wt% of rubidium bis (trifluoromethanesulfonyl) imide and 1 wt% of lithium difluoro bisoxalato phosphate (weight ratio 1: 2) were included as the electrolyte additive.
  • a nonaqueous electrolyte solution and a lithium secondary battery were prepared.
  • the electrolyte solution additive contained 0.5 wt% cesium bis (trifluoromethanesulfonyl) imide and 0.25 wt% lithium difluoro bisoxalato phosphate (weight ratio 1: 0.5)
  • a nonaqueous electrolyte solution and a lithium secondary battery were prepared.
  • the electrolyte solution additive contained 0.5 wt% cesium bis (trifluoromethanesulfonyl) imide and 2.25 wt% lithium difluoro bisoxalato phosphate (weight ratio 1: 4.5).
  • a nonaqueous electrolyte solution and a lithium secondary battery were prepared.
  • the electrolyte solution additive contained 0.5 wt% cesium bis (fluorosulfonyl) imide and 0.5 wt% lithium difluoro bisoxalato phosphate (weight ratio 1: 1).
  • a nonaqueous electrolyte solution and a lithium secondary battery were prepared.
  • the lithium secondary batteries of Example 1, Examples 19 to 25, and Comparative Example 1 were stored at 60 ° C., and then output was calculated using a voltage difference generated by discharging at SOC at 50% for 5 seconds at 50% of SOC. The result is shown in FIG.

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Abstract

The present invention can provide an electrolyte additive comprising a salt of an anion, derived from a nitrogen-atom-containing compound, and Cs+ or Rb+. The present invention can also provide an electrolyte additive further comprising lithium difluorobisoxalatophosphate. The present invention provides a nonaqueous electrolyte comprising a lithium salt, a nonaqueous organic solvent, and the electrolyte additive and can provide a lithium secondary battery comprising: a positive electrode comprising a positive active material; a negative electrode comprising a negative active material; a separator interposed between the positive electrode and the negative electrode; and the nonaqueous electrolyte.

Description

전해액 첨가제 및 이를 포함하는 리튬 이차 전지Electrolyte additive and lithium secondary battery comprising same
본 발명은 전해액 첨가제 및 이를 비수 전해액에 포함한 리튬 이차 전지에 관한 것이다.The present invention relates to an electrolyte additive and a lithium secondary battery including the same in a nonaqueous electrolyte.
최근 정보 통신 산업의 발전에 따라 전자 기기가 소형화, 경량화, 박형화 및 휴대화되고 있다. 그 결과, 이러한 전자 기기의 전원으로 사용되는 전지의 고에너지 밀도화에 대한 요구가 높아지고 있다. 리튬 이차전지는 이러한 요구를 가장 잘 충족시킬 수 있는 전지로서, 현재 이에 대한 연구가 활발히 진행되고 있다.Recently, with the development of the information and communication industry, electronic devices have become smaller, lighter, thinner and more portable. As a result, the demand for higher energy density of batteries used as power sources for such electronic devices is increasing. Lithium secondary batteries are the batteries that can best meet these demands, and research on these is being actively conducted.
리튬 이차전지는 양극, 음극 및 상기 양극과 음극 사이에 리튬 이온의 이동 경로를 제공하는 전해액과 세퍼레이터로 구성되는 전지로서, 리튬 이온이 상기 양극 및 음극에서 흡장 및 방출될 때의 산화, 환원 반응에 의해 전기에너지를 생성한다.A lithium secondary battery is a battery composed of a positive electrode, a negative electrode, and an electrolyte solution and a separator that provides a movement path of lithium ions between the positive electrode and the negative electrode, and is used for oxidation and reduction reactions when lithium ions are occluded and discharged from the positive electrode and the negative electrode. Thereby generating electrical energy.
리튬 이차전지의 평균 방전 전압은 약 3.6 내지 3.7V로서, 다른 알칼리 전지, 니켈-카드뮴 전지 등에 비하여 방전 전압이 높은 것이 장점 중의 하나이다. 이러한 높은 구동 전압을 내기 위해서는 충방전 전압 영역인 0 내지 4.2V에서 전기화학적으로 안정한 전해액 조성이 필요하다. The average discharge voltage of the lithium secondary battery is about 3.6 to 3.7 V, which is one of the advantages of higher discharge voltage than other alkaline batteries, nickel-cadmium batteries, and the like. In order to achieve such a high driving voltage, an electrochemically stable electrolyte composition is required in the charge and discharge voltage range of 0 to 4.2V.
리튬 이차전지의 초기 충전시 리튬 금속 산화물 등의 양극 활물질로부터 나온 리튬 이온은 흑연계 등의 음극 활물질로 이동하여, 음극 활물질의 층간에 삽입된다. 이때, 리튬은 반응성이 강하므로 흑연계 등의 음극 활물질 표면에서 전해액과 음극 활물질을 구성하는 탄소가 반응하여 Li2CO3, Li2O 또는 LiOH 등의 화합물을 생성한다. 이들 화합물은 흑연계 등의 음극 활물질의 표면에 일종의 SEI(Solid Electrolyte Interface) 막을 형성하게 된다.During the initial charging of the lithium secondary battery, lithium ions derived from the positive electrode active material such as lithium metal oxide are moved to the negative electrode active material such as graphite and inserted into the interlayer of the negative electrode active material. At this time, since lithium is highly reactive, the electrolyte and the carbon constituting the negative electrode active material react on the surface of the negative electrode active material such as graphite to generate a compound such as Li 2 CO 3 , Li 2 O, or LiOH. These compounds form a kind of SEI (Solid Electrolyte Interface) film on the surface of an anode active material such as graphite.
SEI 막은 이온 터널의 역할을 수행하여 리튬 이온만을 통과시킨다. SEI 막은 이러한 이온 터널의 효과로서, 전해액 중에서 리튬 이온과 함께 이동하는 분자량이 큰 유기 용매 분자가 음극 활물질의 층간에 삽입되어 음극 구조가 파괴되는 것을 막아준다. 따라서, 전해액과 음극 활물질의 접촉을 방지함으로써 전해액의 분해가 발생하지 않고, 전해액 중의 리튬 이온의 양이 가역적으로 유지되어 안정적인 충방전이 유지된다.The SEI membrane acts as an ion tunnel, passing only lithium ions. The SEI membrane is an effect of this ion tunnel, which prevents the breakdown of the negative electrode structure by intercalation of organic solvent molecules having a large molecular weight moving with lithium ions in the electrolyte between the layers of the negative electrode active material. Therefore, by preventing contact between the electrolyte solution and the negative electrode active material, decomposition of the electrolyte solution does not occur, and the amount of lithium ions in the electrolyte solution is reversibly maintained to maintain stable charge and discharge.
종래에는 전해액 첨가제를 포함하지 않거나 열악한 특성의 전해액 첨가제를 포함하는 전해액의 경우 불균일한 SEI막의 형성으로 인해 수명 특성의 향상을 기대하기 어려웠다. 더욱이, 전해액 첨가제를 포함하는 경우에도 그 투입량을 필요량으로 조절하지 못하는 경우, 상기 전해액 첨가제로 인해 고온 또는 고전압 반응시 양극 표면이 분해되거나 전해액이 산화 반응을 일으켜 궁극적으로 이차전지의 비가역 용량이 증가하고 수명 특성이 저하되는 문제가 있었다.Conventionally, in the case of an electrolyte solution containing no electrolyte additive or an electrolyte additive having poor properties, it is difficult to expect improvement in lifespan characteristics due to the formation of a non-uniform SEI film. Furthermore, even when the electrolyte additive is included, when the input amount is not adjusted to the required amount, the electrolyte additive may decompose the surface of the anode during the high temperature or high voltage reaction, or the electrolyte may oxidize, thereby ultimately increasing the irreversible capacity of the secondary battery. There was a problem that the service life characteristics are lowered.
본 발명의 해결하고자 하는 과제는 신규한 전해액 첨가제를 제공하는 것이다.The problem to be solved of the present invention is to provide a novel electrolyte additive.
더하여 본 발명이 이루고자 다른 기술적 과제는 양극 활물질을 포함하는 양극, 음극 활물질을 포함하는 음극, 상기 양극과 상기 음극 사이에 개재된 분리막 및 본 발명의 전해액 첨가제 함유 비수성 전해액을 포함하는 리튬 이차전지를 제공하는 것이다.In addition, another technical problem to be achieved by the present invention is a lithium secondary battery comprising a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator interposed between the positive electrode and the negative electrode and a non-aqueous electrolyte containing the electrolyte additive of the present invention To provide.
상기 과제를 해결하기 위하여 본 발명은 질소 원자 함유 화합물 유래 음이온과 Cs+ 또는 Rb+와의 염을 포함하는 전해액 첨가제를 제공한다.In order to solve the above problems, the present invention provides an electrolyte additive comprising a salt of a nitrogen atom-containing compound-derived anion and Cs + or Rb + .
또한, 본 발명은 상기 전해액 첨가제에 리튬 디플루오로 비스옥살레이토 포스페이트를 더 포함하는 것인 전해액 첨가제를 제공한다.In addition, the present invention provides an electrolyte additive which further comprises lithium difluoro bisoxalato phosphate in the electrolyte additive.
본 발명은 리튬염, 비수성 유기용매 및 상기 전해액 첨가제를 포함하는 것인 비수성 전해액을 제공한다.The present invention provides a non-aqueous electrolyte comprising a lithium salt, a non-aqueous organic solvent and the electrolyte additive.
또한, 본 발명은 양극 활물질을 포함하는 양극, 음극 활물질을 포함하는 음극, 상기 양극과 상기 음극 사이에 개재된 분리막 및 상기 비수성 전해액을 포함하는 리튬 이차전지를 제공한다.The present invention also provides a lithium secondary battery including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator interposed between the positive electrode and the negative electrode and the non-aqueous electrolyte.
본 발명의 일 실시예에 따른 전해액 첨가제를 포함하여 형성된 이차전지는 고온, 및 저온수명 특성, 고온저장 특성 및 두께 변화율이 우수하다.The secondary battery formed by including the electrolyte additive according to an embodiment of the present invention is excellent in high temperature and low temperature life characteristics, high temperature storage characteristics and thickness change rate.
나아가, 본 발명의 다른 일 실시예에 따른 질소 원자 함유 화합물 유래 음이온과 Cs+ 또는 Rb+와의 염을 포함하는 화합물 및 리튬 디플루오로 비스옥살레이토 포스페이트를 포함하는 전해액 첨가제를 포함하여 형성된 이차전지는 고온 출력 특성이 우수하다.Furthermore, a secondary battery formed by including a compound containing a salt of a nitrogen atom-containing compound-derived anion and Cs + or Rb + and an electrolyte additive comprising lithium difluoro bisoxalato phosphate according to another embodiment of the present invention Excellent high temperature output characteristics.
도 1은 본 발명의 실시예 및 비교예의 고온 출력 특성을 나타내는 그래프이다.1 is a graph showing the high-temperature output characteristics of the Examples and Comparative Examples of the present invention.
이하, 본 발명에 대한 이해를 돕기 위해 본 발명을 더욱 상세하게 설명한다. 본 명세서 및 청구범위에 사용된 용어나 단어는 통상적이거나 사전적인 의미로 한정해서 해석되어서는 아니 되며, 발명자는 그 자신의 발명을 가장 최선의 방법으로 설명하기 위해 용어의 개념을 적절하게 정의할 수 있다는 원칙에 입각하여 본 발명의 기술적 사상에 부합하는 의미와 개념으로 해석되어야만 한다. Hereinafter, the present invention will be described in more detail to aid in understanding the present invention. The terms or words used in this specification and claims are not to be construed as limiting in their usual or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best explain their invention in the best way possible. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.
본 발명의 일 실시예 따른 신규한 전해액 첨가제는, 질소 원자 함유 화합물 유래 음이온과 Cs+ 또는 Rb+와의 염을 포함하는 것일 수 있다.The novel electrolyte additive according to one embodiment of the present invention may include a salt of a nitrogen atom-containing compound-derived anion and Cs + or Rb + .
여기서, 상기 질소 원자 함유 화합물 유래 음이온은 아미드계 음이온, 이미드계 음이온, 니트릴계 음이온, 니트리트 음이온, 및 니트레이트 음이온으로 이루어진 군에서 선택되는 1종 이상을 포함하는 것일 수 있다.Here, the nitrogen atom-containing compound-derived anion may include one or more selected from the group consisting of an amide anion, an imide anion, a nitrile anion, a nitrite anion, and a nitrate anion.
구체적으로, 상기 아미드계 음이온은 디메틸포름아미드 음이온, 디메틸아세트아미드 음이온, 디에틸포름아미드 음이온, 디에틸아세트아미드 음이온, 메틸에틸포름아미드 음이온, 및 메틸에틸아세트아미드 음이온으로 이루어진 군에서 선택되는 1종 이상을 포함하는 것일 수 있다.Specifically, the amide-based anion is one selected from the group consisting of dimethylformamide anion, dimethylacetamide anion, diethylformamide anion, diethylacetamide anion, methylethylformamide anion, and methylethylacetamide anion. It may be included above.
또한, 상기 이미드계 음이온은 이하 화학식 1로 나타내는 것일 수 있다.In addition, the imide-based anion may be represented by Formula 1 below.
[화학식 1][Formula 1]
Figure PCTKR2017009758-appb-I000001
Figure PCTKR2017009758-appb-I000001
여기서, R1　및 R2는 각각 플루오로기 또는 탄소수 1 내지 4의 플루오로 알킬기이고, 또는 R1　및 R2는 서로 연결되어 탄소수 1 내지 4의 플루오로 시클로알킬렌(fluoro cycloalkylene) 고리를 형성하여도 된다.Wherein R 1 and R 2 are each a fluoro group or a fluoroalkyl group having 1 to 4 carbon atoms, or R 1 and R 2 are connected to each other to form a fluoro cycloalkylene ring having 1 to 4 carbon atoms You may also do it.
상기 니트릴계 음이온은 아세토니트릴 음이온, 프로피오니트릴 음이온, 부티로니트릴 음이온, 발레로니트릴 음이온, 카프릴로니트릴 음이온, 헵탄니트릴 음이온, 싸이클로펜탄 카보니트릴 음이온, 싸이클로헥산 카보니트릴 음이온, 2-플루오로벤조니트릴 음이온, 4-플루오로벤조니트릴 음이온, 다이플루오로벤조니트릴 음이온, 트리플루오로벤조니트릴 음이온, 페닐아세토니트릴 음이온, 2-플루오로페닐아세토니트릴 음이온, 및 4-플루오로페닐아세토니트릴 음이온으로 이루어진 군에서 선택되는 1종 이상을 포함하는 것일 수 있다.The nitrile anions include acetonitrile anion, propionitrile anion, butyronitrile anion, valeronitrile anion, caprylonitrile anion, heptanenitrile anion, cyclopentane carbonitrile anion, cyclohexane carbonitrile anion, and 2-fluorobenzo Nitrile anion, 4-fluorobenzonitrile anion, difluorobenzonitrile anion, trifluorobenzonitrile anion, phenylacetonitrile anion, 2-fluorophenylacetonitrile anion, and 4-fluorophenylacetonitrile anion It may be one containing at least one selected from the group.
나아가, 상기 화학식 1로 나타내는 화합물은 하기 화학식 2 내지 6으로 이루어진 군에서 선택되는 1종 이상을 포함하는 것일 수 있다.Furthermore, the compound represented by Chemical Formula 1 may include one or more selected from the group consisting of the following Chemical Formulas 2 to 6.
[화학식 2][Formula 2]
Figure PCTKR2017009758-appb-I000002
Figure PCTKR2017009758-appb-I000002
[화학식 3][Formula 3]
Figure PCTKR2017009758-appb-I000003
Figure PCTKR2017009758-appb-I000003
[화학식 4][Formula 4]
Figure PCTKR2017009758-appb-I000004
Figure PCTKR2017009758-appb-I000004
[화학식 5][Formula 5]
Figure PCTKR2017009758-appb-I000005
Figure PCTKR2017009758-appb-I000005
[화학식 6][Formula 6]
Figure PCTKR2017009758-appb-I000006
Figure PCTKR2017009758-appb-I000006
본 발명의 일 실시예에 따르면, 상기 전해액 첨가제는 세슘 비스(트리플루오로메탄설포닐)이미드, 세슘 니트레이트, 루비듐 비스(트리플루오로메탄설포닐)이미드, 루비듐 니트레이트 및 세슘 비스(플루오로설포닐)이미드로 이루어진 군에서 선택되는 1종 이상을 포함하는 것일 수 있다.According to one embodiment of the present invention, the electrolyte additive is cesium bis (trifluoromethanesulfonyl) imide, cesium nitrate, rubidium bis (trifluoromethanesulfonyl) imide, rubidium nitrate and cesium bis ( It may be one containing one or more selected from the group consisting of fluorosulfonyl) imide.
또한, 본 발명은 리튬염, 비수성 유기용매 및 상기 전해액 첨가제를 포함하는 것인 비수성 전해액을 제공할 수 있다.In addition, the present invention can provide a non-aqueous electrolyte solution containing a lithium salt, a non-aqueous organic solvent and the electrolyte additive.
상기 첨가제는 전해액 속에서 양극 및 음극 표면에 피막을 형성할 수 있다. 일반적으로 이차전지가 충방전을 거듭하는 환경에서는 양극 표면에서 산화 반응이, 음극 표면에서 환원 반응이 진행된다. 본 발명의 일 실시예에 따른 첨가제는 상기 양극 및 음극 표면에 피막을 형성하여 양극으로부터 발생되는 리튬 이온의 용출을 효과적으로 제어하고, 양극이 분해되는 현상을 방지할 수 있다. 보다 구체적으로, 음극 표면에 상기 첨가제로 인하여 생성된 피막은 충방전 시의 환원반응을 통하여 일부 분해되지만, 분해되어진 첨가제는 다시 양극 표면으로 이동하여 산화 반응을 통해 다시 양극 표면에 피막을 형성할 수 있다. 따라서, 수차례의 충방전을 거듭하더라도, 상기 첨가제는 양극 표면에의 피막을 유지하여, 양극에서 리튬 이온의 과도한 용출을 효과적으로 방지할 수 있다. 이러한 이유는 명확하게 밝혀진 것은 아니나 본 발명의 일 실시예에 따른 첨가제가 가지고 있는 Cs+, 또는 Rb+ 가 알칼리족 원소의 이온으로서, 양극 및 음극에 존재하는 Li+와 친한 화학적 성질에 기인하는 것으로 추측되어 진다. 따라서, 본 발명의 일 실시예에 따른 이차전지는 양극이 충방전을 거듭하더라도 그 구조가 붕괴되지 않고, 효과적으로 유지되어 이차전지의 고온 및 저온 수명 특성을 개선시킬 수 있다. The additive may form a film on the surface of the positive electrode and the negative electrode in the electrolyte. In general, in an environment where secondary batteries are repeatedly charged and discharged, an oxidation reaction is performed on the surface of the cathode and a reduction reaction is performed on the surface of the anode. The additive according to an embodiment of the present invention may form a film on the surfaces of the cathode and the anode to effectively control the dissolution of lithium ions generated from the anode, and may prevent a phenomenon in which the anode is decomposed. More specifically, the film formed by the additive on the surface of the cathode is partially decomposed through the reduction reaction during charging and discharging, but the decomposed additive may move back to the surface of the anode and form a film on the surface of the anode again through an oxidation reaction. have. Therefore, even after repeated charging and discharging several times, the additive can maintain the film on the surface of the positive electrode, thereby effectively preventing excessive elution of lithium ions at the positive electrode. The reason for this is not clear, but Cs + or Rb + of the additive according to an embodiment of the present invention is an ion of an alkali element, which is due to the chemical properties of Li + present in the positive electrode and the negative electrode. It is assumed. Therefore, the secondary battery according to an embodiment of the present invention does not collapse the structure even if the positive electrode is repeatedly charged and discharged, it can be effectively maintained to improve the high temperature and low temperature life characteristics of the secondary battery.
종래, 리튬 이차 전지에서 통상적인 전해액 또는 첨가제를 사용하는 경우, 첨가제는 양극과 전해액 사이의 반응성 증가로 인해 양극 표면의 분해(degradation) 및 전해액의 산화 반응이 발생하여 전지의 안전성 및 성능 저하가 유발되었다. 이러한 현상은 특히 저온이나 고온 저장 시 종래의 이용되는 첨가제들이 너무 많이 분해되어 양극에 매우 두꺼운 절연체(insulator)를 형성함으로써, 리튬 이온의 이동을 막아 회복 용량(recovery capacity)이 전혀 나오지 않는 문제점이 발생하였다. Conventionally, when a conventional electrolyte or additive is used in a lithium secondary battery, the additive causes degradation of the surface of the cathode and oxidation of the electrolyte due to increased reactivity between the cathode and the electrolyte, resulting in deterioration of battery safety and performance. It became. This phenomenon is particularly problematic in the case of low temperature or high temperature storage, so that conventionally used additives decompose too much to form a very thick insulator on the anode, thereby preventing the migration of lithium ions, resulting in no recovery capacity. It was.
그러나 본 발명의 일 실시예에 따른 첨가제는 양극과 전해액간의 부반응성 및 발생 접촉면을 감소시켜 전지의 안전성을 향상 향상시킬 수 있다. 높은 반응 전위 및 사이클 진행에 따른 반응 전위의 변화가 거의 없는 특성으로 인해 종래 첨가제 분해 및 반응 전위의 급격한 변화로 인한 전지의 성능 저하를 방지할 수 있다. 나아가, 상기 첨가제는 양극에서 산화반응을 통하여 안정한 피막을 형성함으로써, 양극의 분해를 방지하고 용출을 억제하므로 고전압 환경 하에서의 양극을 보다 안정하게 보호할 수 있다.However, the additive according to the embodiment of the present invention may improve the safety of the battery by reducing side reactions and generated contact surfaces between the positive electrode and the electrolyte. Due to the characteristics of the high reaction potential and little change in the reaction potential with the progress of the cycle, it is possible to prevent the degradation of the battery due to the conventional additive decomposition and sudden change of the reaction potential. Furthermore, the additive forms a stable film through an oxidation reaction at the anode, thereby preventing decomposition of the anode and suppressing elution, thereby more stably protecting the anode under a high voltage environment.
본 발명의 다른 일 실시예에 의하면, 상기 첨가제로서는 리튬 이차전지의 안정성이나, 출력의 향상을 위하여 이종의 첨가제를 추가로 더 포함할 수 있다. 이는, 상술한 질소 원자 함유 화합물 유래 음이온과 Cs+ 또는 Rb+와의 염을 포함하는 첨가제에 리튬 디플루오로 비스옥살레이토 포스페이트를 더 포함하는 것일 수 있고, 보다 구체적으로는 세슘 비스(트리플루오로메탄설포닐)이미드, 세슘 니트레이트, 루비듐 비스(트리플루오로메탄설포닐)이미드 루비듐 니트레이트 및 세슘 비스(플루오로설포닐)이미드로 이루어진 군에서 선택되는 1종 이상 및 리튬 디플루오로 비스옥살레이토 포스페이트를 포함하는 것일 수 있다.According to another embodiment of the present invention, the additive may further include a heterogeneous additive to improve the stability of the lithium secondary battery or the output. This may further include lithium difluoro bisoxalato phosphate in an additive comprising a salt of the above-described nitrogen atom-containing compound anion and Cs + or Rb + , more specifically cesium bis (trifluoromethane One or more selected from the group consisting of sulfonyl) imide, cesium nitrate, rubidium bis (trifluoromethanesulfonyl) imide rubidium nitrate and cesium bis (fluorosulfonyl) imide and lithium difluoro bis It may be one containing oxalato phosphate.
리튬 디플루오로 비스옥살레이토 포스페이트는 양극 및 음극 표면에 안정한 SEI 피막을 형성할 수 있는데, 질소 원자 함유 화합물 유래 음이온과 Cs+ 또는 Rb+와의 염을 포함하는 첨가제가 리튬 디플루오로 비스옥살레이토 포스페이트와 동시에 전해액에 포함됨으로써, 리튬 디플루오로 비스옥살레이토 포스페이트로부터 형성되는 음극 및 양극의 SEI 피막을 보다 균일하게 형성시킬 수 있고, 균일한 피막의 형성에 따라서, 리튬 이온의 이동이 용이해지기 때문에 보다 향상된 출력 특성을 확보할 수 있다.Lithium difluoro bisoxalato phosphate can form a stable SEI film on the surface of the anode and cathode. An additive comprising a salt of a nitrogen atom-containing compound anion and Cs + or Rb + is lithium difluoro bisoxalato phosphate. In addition, by being included in the electrolyte solution, the SEI film of the negative electrode and the positive electrode formed from lithium difluoro bisoxalato phosphate can be formed more uniformly, and the movement of lithium ions becomes easier according to the formation of the uniform film. Better output characteristics can be obtained.
상술한 바와 같은 효과를 위하여 상기 Cs+ 또는 Rb+와의 염을 포함하는 첨가제 및 리튬 디플루오로 비스옥살레이토 포스페이트는 중량비로서 1 : 1 내지 1 : 4로 전해액에 포함되는 것이 바람직하다.For the effects as described above, the additive including the salt with Cs + or Rb + and lithium difluoro bisoxalato phosphate are preferably included in the electrolyte at a weight ratio of 1: 1 to 1: 4.
본 발명의 일 실시예에 따르면, 상기 첨가제의 함량은 상기 비수성 전해액 총량을 기준으로 0.05~10 중량%일 수 있다. 바람직하게는 상기 첨가제의 함량은 상기 비수성 전해액 총량을 기준으로 0.1~3 중량%인 것일 수 있다.According to one embodiment of the invention, the content of the additive may be 0.05 to 10% by weight based on the total amount of the non-aqueous electrolyte. Preferably the content of the additive may be 0.1 to 3% by weight based on the total amount of the non-aqueous electrolyte.
상기 첨가제의 함량이 0.05 중량% 보다 적으면 리튬 이차 전지의 저온 및 고온 저장 특성 및 고온 수명 특성의 개선의 효과가 미미하고, 상기 첨가제의 함량이 10 중량%를 초과하면 과도한 피막형성으로 인하여, 저항이 증가하는 문제가 발생할 수 있다. If the content of the additive is less than 0.05% by weight, the effect of improving the low temperature and high temperature storage characteristics and the high temperature life characteristics of the lithium secondary battery is insignificant, and if the content of the additive exceeds 10% by weight due to excessive film formation, resistance This increasing problem can occur.
특히, 상기 첨가제를 리튬 이차 전지에 적용할 경우 Cs+ 또는 Rb+와의 염을 포함하는 첨가제가 가지는 저온 및 고온 저장 특성과 고온 수명 특성의 향상, 두께 변화율을 최소로 하여 형성된 이차전지의 안정성을 확보할 수 있으며, 특히 고온에서의 이차전지 수명, 저항 특성을 향상시킨다는 효과에 더하여, 균일한 피막 형성으로 인하여 형성된 이차전지의 고온 출력 특성도 확보할 수 있다.In particular, when applying the additives in the lithium secondary battery, Cs +, or the improvement of low-temperature and high-temperature storage properties and high-temperature cycle life characteristics additives having to include salts with Rb +, ensure the stability of the secondary battery is formed by minimizing the thickness variation rate In addition to the effect of improving the secondary battery life and resistance characteristics, particularly at high temperatures, it is possible to ensure the high temperature output characteristics of the secondary battery formed due to uniform film formation.
상기 리튬염은 당 분야에서 통상적으로 사용되는 리튬염을 사용할 수 있으며, 예를 들어 LiPF6, LiFSI, LiAsF6, LiCF3SO3, LiN(CF3SO2)2, LiBF4, LiSbF6, LiN(C2F5SO2)2, LiAlO4, LiAlCl4, LiSO3CF3, LiTFSI, LiDFOB 및 LiClO4로 이루어진 군에서 선택되는 1종 이상을 포함하는 것일 수 있다. 상기 리튬염은 비수성 전해액 중의 농도가 0.01 mole/ℓ 내지 2 mole/ℓ인 것이 바람직하며, 0.01 mole/ℓ 내지 1 mole/ℓ이 더욱 바람직하다.The lithium salt may be used a lithium salt commonly used in the art, for example LiPF 6 , LiFSI, LiAsF 6 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiBF 4 , LiSbF 6 , LiN It may include one or more selected from the group consisting of (C 2 F 5 SO 2 ) 2 , LiAlO 4 , LiAlCl 4 , LiSO 3 CF 3 , LiTFSI, LiDFOB, and LiClO 4 . The lithium salt preferably has a concentration in the non-aqueous electrolyte solution of 0.01 mole / l to 2 mole / l, more preferably 0.01 mole / l to 1 mole / l.
또한, 본 발명에 사용되는 비수성 유기 용매로는 리튬 이차전지용 전해액에 통상적으로 사용되는 유기 용매들을 제한 없이 사용할 수 있으며, 예를 들면 에테르, 에스테르, 아미드, 선형 카보네이트, 환형 카보네이트, 인산계 화합물, 니트릴계 화합물, 불소화 에테르계 화합물, 불소화 방향족계 화합물 등을 각각 단독으로 또는 2종 이상 혼합하여 사용할 수 있다.In addition, as the non-aqueous organic solvent used in the present invention, organic solvents commonly used in lithium secondary battery electrolytes can be used without limitation, for example, ethers, esters, amides, linear carbonates, cyclic carbonates, phosphoric acid compounds, A nitrile compound, a fluorinated ether compound, a fluorinated aromatic compound, etc. can be used individually or in mixture of 2 or more types, respectively.
그 중에서 대표적으로 환형 카보네이트, 선형 카보네이트 또는 이들의 혼합물인 카보네이트 화합물을 포함할 수 있다. 상기 환형 카보네이트 화합물의 구체적인 예로는 에틸렌 카보네이트(EC), 프로필렌 카보네이트(PC), 1,2-부틸렌 카보네이트, 2,3-부틸렌 카보네이트, 1,2-펜틸렌 카보네이트, 2,3-펜틸렌 카보네이트, 비닐렌 카보네이트, 및 이들의 할로겐화물로 이루어진 군에서 선택되는 1종 이상을 포함하는 것일 수 있다. Among them, carbonate compounds which are typically cyclic carbonates, linear carbonates or mixtures thereof may be included. Specific examples of the cyclic carbonate compound include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene It may include one or more selected from the group consisting of carbonates, vinylene carbonates, and halides thereof.
또한 상기 선형 카보네이트 화합물의 구체적인 예로는 디메틸 카보네이트(DMC), 디에틸 카보네이트(DEC), 디프로필 카보네이트(DPC), 에틸메틸 카보네이트(EMC), 메틸프로필 카보네이트(MPC) 및 에틸프로필 카보네이트(EPC)로 이루어진 군에서 선택되는 1종 이상을 포함할 수 있으나, 이에 한정되는 것은 아니다. Specific examples of the linear carbonate compounds include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC) and ethylpropyl carbonate (EPC). It may include one or more selected from the group consisting of, but is not limited thereto.
특히, 상기 카보네이트계 전해액 용매 중 환형 카보네이트는 프로필렌 카보네이트, 에틸렌 카보네이트 및 이들의 혼합물을 포함하는 것이 바람직하며, 이는 고점도의 유기 용매로서 유전율이 높아 전해액 내의 리튬염을 잘 해리시키므로 바람직하게 사용될 수 있다. In particular, the cyclic carbonate in the carbonate-based electrolyte solvent preferably includes propylene carbonate, ethylene carbonate, and mixtures thereof, and may be preferably used because it dissociates lithium salt in the electrolyte well because of high dielectric constant as a high-viscosity organic solvent.
또한, 상기 환형 카보네이트에 디에틸 카보네이트, 디메틸 카보네이트, 에틸메틸 카보네이트 및 이들의 혼합물인 선형 카보네이를 혼합하여 사용하는 것이 바람직하다. 이들은 저점도, 저유전율 선형 카보네이트를 적당한 비율로 혼합하여 사용하면 높은 전기 전도율을 가지는 전해액을 만들 수 있어서 더욱 바람직하게 사용될 수 있다. In addition, it is preferable to use diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate, and a linear carbonene, which is a mixture thereof, with the cyclic carbonate. They can be more preferably used because low viscosity, low dielectric constant linear carbonate can be mixed in an appropriate ratio to make an electrolyte having high electrical conductivity.
또한, 상기 전해액 용매 중 에스테르로는 메틸 아세테이트, 에틸 아세테이트, 프로필 아세테이트, 에틸 프로피오네이트(EP), 프로필 프로피오네이트, 메틸 프로피오네이트(MP), γ-부티로락톤, γ-발레로락톤, γ-카프로락톤, δ-발레로락톤 및 ε-카프로락톤으로 이루어진 군에서 선택되는 1종 이상을 포함할 수 있으며, 이중에서도 특히 저점도인 에틸 프로피오네이트(EP), 프로필 프로피오네이트, 메틸 프로피오네이트(MP) 및 이들의 혼합물을 포함하는 것이 바람직하다.In addition, the ester in the electrolyte solvent is methyl acetate, ethyl acetate, propyl acetate, ethyl propionate (EP), propyl propionate, methyl propionate (MP), γ-butyrolactone, γ-valerolactone , γ-caprolactone, δ-valerolactone and ε-caprolactone, and may include one or more selected from among them, particularly low viscosity ethyl propionate (EP), propyl propionate, It is preferred to include methyl propionate (MP) and mixtures thereof.
상기 인산 계열 용매 및 모노 니트릴 계열 용매는 불소원자(F)로 치환된 것을 사용할 수 있다. 상기 용매가 할로겐 원소로 치환되면 난연성이 더욱 증가하지만, Cl, Br 또는 I 등으로 치환이 되면 용매의 반응성이 함께 커져서 전해액으로 바람직하지 않게 된다.The phosphoric acid solvent and the mononitrile solvent may be substituted with a fluorine atom (F). When the solvent is substituted with a halogen element, the flame retardancy is further increased, but when the solvent is substituted with Cl, Br, or I, the reactivity of the solvent increases together, which is not preferable as an electrolyte solution.
본 발명의 비수 전해액에 있어서, 상기 인산계 화합물의 비제한적인 예로는, 트리메틸포스핀 옥사이드, 트리에틸포스핀 옥사이드, 트리프로필포스핀 옥사이드, 트리페닐포스핀 옥사이드, 다이에틸 메틸포스포네이트, 다이메틸 메틸포스포네이트, 다이페닐 메틸포스포네이트, 비스(2,2,2-트리플루오로에틸) 메틸포스포네이트, 트리메틸 포스페이트, 트리에틸 포스페이트, 트리프로필 포스페이트, 에틸 메틸 페닐 포스페이트 등이 있다. 이들 인산 계열 용매는 단독으로 또는 2종 이상을 혼합하여 사용할 수 있다.In the nonaqueous electrolyte of the present invention, non-limiting examples of the phosphate compound include trimethylphosphine oxide, triethylphosphine oxide, tripropylphosphine oxide, triphenylphosphine oxide, diethyl methylphosphonate, di Methyl methylphosphonate, diphenyl methylphosphonate, bis (2,2,2-trifluoroethyl) methylphosphonate, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, ethyl methyl phenyl phosphate and the like. These phosphoric acid solvents may be used alone or in combination of two or more thereof.
또한, 상기 니트릴계 화합물의 비제한적인 예로는, 아세토니트릴, 프로피오니트릴, 부티로니트릴, 발레로니트릴, 카프릴로니트릴, 헵탄니트릴, 싸이클로펜탄 카보니트릴, 싸이클로헥산 카보니트릴, 2-플루오로벤조니트릴, 4-플루오로벤조니트릴, 다이플루오로벤조니트릴, 트리플루오로벤조니트릴, 페닐아세토니트릴, 2-플루오로페닐아세토니트릴, 4-플루오로페닐아세토니트릴 등이 있다. 이들 니트릴 계열 용매는 단독으로 또는 2종 이상을 혼합하여 사용할수 있다.In addition, non-limiting examples of the nitrile-based compound include acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzo Nitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile and the like. These nitrile solvents can be used individually or in mixture of 2 or more types.
또한, 상기 불소화 에테르계 화합물의 비제한적인 예로는, 비스-,2,2-트리플루오로에틸 에테르,n-부틸 1,1,2,2-테트라플루오로에틸 에테르, 2,2,3,3,3-펜타플루오르프로필 메틸 에테르, 2,2,3,3,3-펜타플루오로프로필 1,1,2,2-테트라플루오로에틸 에테르, 1,1,2,2-테트라플루오로에틸 메틸 에테르, 1,1,2,2-테트라플루오로에틸 에틸 에테르, 트리플루오로에틸 도데카플루오로헥실 에테르 등이 있다. 이들 불소화 에테르 계열 용매는 단독으로 또는 2종 이상을 혼합하여 사용할 수 있다.Further, non-limiting examples of the fluorinated ether compound include bis-, 2,2-trifluoroethyl ether, n- butyl 1,1,2,2-tetrafluoroethyl ether, 2,2,3, 3,3-pentafluoropropyl methyl ether, 2,2,3,3,3- pentafluoropropyl 1,1,2,2-tetrafluoroethyl ether, 1,1,2,2-tetrafluoroethyl Methyl ether, 1,1,2,2-tetrafluoroethyl ethyl ether, trifluoroethyl dodecafluorohexyl ether, and the like. These fluorinated ether solvents may be used alone or in combination of two or more thereof.
또한, 방향족 화합물계 화합물 용매의 비제한적인 예로서는, 클로로 벤젠, 클로로톨루엔이나 플루오로 벤젠 등의 할로겐화 벤젠 화합물, tert-부틸 벤전, tert-펜틸 벤젠이나, 싸이클로 헥실 벤젠, 수소 비페닐, 수소화 터페닐 등의 알킬화 방향족 화합물을 들 수 있다. 여기서 상기 알킬화 방향족 화합물의 알킬기는 할로겐화 되어 있어도 되며, 일 예로서는 불소화되어 있는 것을 들 수 있다. 이러한 불소화 화합물의 예로서는, 트리플루오로 메톡시 벤젠 등을 들 수 있다.Non-limiting examples of aromatic compound solvents include halogenated benzene compounds such as chlorobenzene, chlorotoluene and fluorobenzene, tert-butyl benzene, tert-pentyl benzene, cyclohexyl benzene, hydrogen biphenyl and hydrogenated terphenyl. Alkylated aromatic compounds, such as these, are mentioned. Here, the alkyl group of the said alkylated aromatic compound may be halogenated, and the fluorinated thing is mentioned as an example. Examples of such fluorinated compounds include trifluoro methoxy benzene and the like.
한편, 본 발명의 일 실시예에 따르는 리튬 이차 전지는 양극 활물질을 포함하는 양극, 음극 활물질을 포함하는 음극, 및 상기 양극과 상기 음극 사이에 개재된 분리막 및 상기 비수성 전해액을 포함할 수 있다. Meanwhile, the lithium secondary battery according to an embodiment of the present invention may include a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator interposed between the positive electrode and the negative electrode and the non-aqueous electrolyte solution.
상기 양극에 있어서, 양극 활물질은, 리튬을 가역적으로 인터칼레이션/디인터칼레이션 할 수 있는 화합물이면 제한되지 않고 사용될 수 있다.In the positive electrode, the positive electrode active material can be used without limitation as long as it is a compound capable of intercalating / deintercalating lithium.
본 발명의 실시예에 따른 리튬 이차 전지에 있어서, 양극 활물질은, 고용량 특성을 갖는 육박정계 층상 암염 구조, 올리빈 구조, 큐빅구조를 갖는 스피넬의 리튬 전이금속 산화물, 그 외에 V2O5, TiS, MoS로 이루어진 군에서 선택되는 1종 이상을 포함할 수 있다. 더욱 구체적으로, 예를 들면 하기 화학식 7 내지 화학식 9의 화합물로 이루어진 군에서 선택되는 1종 이상을 포함할 수 있다: In the lithium secondary battery according to the embodiment of the present invention, the positive electrode active material is a spinel lithium transition metal oxide having a thin crystal layered rock salt structure, an olivine structure, and a cubic structure having high capacity characteristics, in addition to V 2 O 5 , TiS , MoS may include one or more selected from the group consisting of. More specifically, for example, the composition may include one or more selected from the group consisting of compounds represented by Formulas 7 to 9:
[화학식 7][Formula 7]
Li[NiaCobMnc]O2 (0.1 ≤ c ≤ 0.5,　0　<　a+b　< 0.9, a+b+c=1);Li [Ni a Co b Mn c ] O 2 (0.1 ≦ c ≦ 0.5, 0 <a + b <0.9, a + b + c = 1);
[화학식 8][Formula 8]
LiMn2 - xMxO4 (M=Ni, Co, Fe, P, S, Zr, Ti 및 Al로 이루어진 군에서 선택되는 하나 이상의 원소, 0 < x ≤ 2) ;LiMn 2 - x M x O 4 (M = Ni, Co, Fe, P, S, Zr, Ti and Al, at least one element selected from the group consisting of 0 <x ≤ 2);
[화학식 9][Formula 9]
Li1 + aCoxM1 - xAX4 (M=Al, Mg, Ni, Co, Mn, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn 및 Y 로 이루어진 군에서 선택되는 하나 이상의 원소이고, X는 O, F, 및 N으로 이루어진 군에서 선택되는 하나 이상의 원소이며, A는 P, S 또는 이들의 혼합 원소이고, 0≤a≤0.2, 0.5≤x≤1이다.).Li 1 + a Co x M 1 - x AX 4 (M = Al, Mg, Ni, Co, Mn, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn and Y) At least one element, X is at least one element selected from the group consisting of O, F, and N, and A is P, S or a mixture thereof, and 0 ≦ a ≦ 0.2, 0.5 ≦ x ≦ 1.) .
상기 양극 활물질은 바람직하게는 Li[Ni0.6Co0.2Mn0.2]O2, Li(Ni0.5Co0.2Mn0.3)O2 , Li[Ni1/3Co1/3Mn1/3]O2, 및 LiCoO2로 이루어진 군에서 선택되는 1종 이상을 포함할 수 있다. The positive electrode active material is preferably Li [Ni 0.6 Co 0.2 Mn 0.2 ] O 2 , Li (Ni 0.5 Co 0.2 Mn 0.3 ) O 2 , Li [Ni 1/3 Co 1/3 Mn 1/3 ] O 2 , and It may include one or more selected from the group consisting of LiCoO 2 .
특히 바람직한 실시예에 의하면, 상기 Li[NiaCobMnc]O2을 양극에 이용함으로써, 본 발명의 화학식 1의 화합물과 조합되어 상승 작용을 가질 수 있다. 상기 리튬-니켈-망간-코발트계 산화물의 양극 활물질은 전이 금속 중 Ni의 함량이 증가할수록 충방전 과정에서 상기 양극 활물질의 층상 구조내의 Li +1가 이온과 Ni +2가 이온의 자리가 바뀌는 현상 (cation mixing)이 발생되어 구조가 불안정 해 질 수 있고, 이에 상기 양극 활물질은 전해액과 부반응을 일으키거나, 전이금속의 용출현상 등이 나타난다. 그렇기 때문에 본 발명의 일 실시예에 따른 화학식 1의 전해액 첨가제를 이용하는 경우, 상기 이온의 자리가 바뀌는 현상(cation mixing)을 최소화 할 수 있는 것으로 추측되어 진다.According to a particularly preferred embodiment, by using the Li [Ni a Co b Mn c ] O 2 in the positive electrode, it can have a synergistic effect in combination with the compound of formula (1) of the present invention. In the positive electrode active material of the lithium-nickel-manganese-cobalt-based oxide, as the content of Ni in the transition metal increases, Li + 1 ions and Ni + 2 ions in the layered structure of the positive electrode active material change positions during charge and discharge. (cation mixing) may occur and the structure may become unstable, and thus the positive electrode active material may cause side reactions with the electrolyte, or dissolution of transition metals. Therefore, when using the electrolyte additive of the formula (1) according to an embodiment of the present invention, it is assumed that the phenomenon of the cation mixing (cation mixing) can be minimized.
한편, 상기 음극 활물질로는 비정질 카본 또는 정질 카본을 포함하며, 구체적으로는 난흑연화 탄소, 흑연계 탄소 등의 탄소; LixFe2O3(0≤x≤1), LixWO2(0≤x≤1), SnxMe1 - xMe'yOz (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, 주기율표의 1족, 2족, 3족 원소, 할로겐; 0<x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5 등의 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni계 재료 등을 사용할 수 있다.On the other hand, the negative electrode active material includes amorphous carbon or crystalline carbon, specifically, carbon such as non-graphitized carbon, graphite carbon; LixFe 2 O 3 (0 ≦ x ≦ 1), LixWO 2 (0 ≦ x ≦ 1 ), SnxMe 1 - x Me ' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P , Metal complex oxides such as Si, Group 1, 2, 3 Group elements of the periodic table, halogen, 0 <x ≦ 1, 1 ≦ y ≦ 3, 1 ≦ z ≦ 8); Lithium metal; Lithium alloys; Silicon-based alloys; Tin-based alloys; SnO, SnO 2 , PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , GeO, GeO 2 , Bi 2 O 3 , Bi 2 O 4 , And oxides such as Bi 2 O 5 ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.
또한, 상기 분리막은 다공성 고분자 필름, 예를 들어 에틸렌 단독중합체, 프로필렌 단독 중합체, 에틸렌/부텐 공중합체, 에틸렌/헥센 공중합체 및 에틸렌/메타크릴레이트 공중합체 등과 같은 폴리올레핀계 고분자로 제조한 다공성 고분자 필름이 단독으로 또는 2종 이상이 적층된 것일 수 있다. 이 외에 통상적인 다공성 부직포, 예를 들어 고융점의 유리 섬유, 폴리에틸렌테레프탈레이트 섬유 등으로 된 부직포를 사용할 수 있으며, 이에 한정되는 것은 아니다.In addition, the separator is a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer This may be a single or two or more laminated. In addition to the above, conventional porous nonwoven fabrics such as high-melting glass fibers, polyethylene terephthalate fibers, and the like may be used, but are not limited thereto.
상기 양극 및/또는 음극은 바인더와 용매, 필요에 따라 통상적으로 사용될 수 있는 도전제와 분산제를 혼합 및 교반하여 슬러리를 제조한 후 이를 집전체에 도포하고 압축하여 제조할 수 있다. The positive electrode and / or the negative electrode may be prepared by mixing and stirring a binder, a solvent, a conductive agent and a dispersant which may be commonly used as needed, to prepare a slurry, and then applying the same to a current collector and compressing the same.
상기 바인더로는 폴리비닐리덴플루오라이드-헥사플루오로프로필렌 코폴리머(PVDF-co-HEP), 폴리비닐리덴플루오라이드(polyvinylidenefluoride), 폴리아크릴로니트릴(polyacrylonitrile), 폴리메틸메타크릴레이트(polymethylmethacrylate), 폴리비닐알코올, 카르복시메틸셀룰로오스(CMC), 전분, 히드록시프로필셀룰로오스, 재생 셀룰로오스, 폴리비닐피롤리돈, 테트라플루오로에틸렌, 폴리에틸렌, 폴리프로필렌, 폴리아크릴산, 에틸렌-프로필렌-디엔 모노머(EPDM), 술폰화 EPDM, 스티렌 부티렌 고무(SBR), 불소 고무, 다양한 공중합체 등의 다양한 종류의 바인더 고분자가 사용될 수 있다.The binder may be polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HEP), polyvinylidene fluoride (polyvinylidenefluoride), polyacrylonitrile, polymethylmethacrylate, Polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), Various kinds of binder polymers such as sulfonated EPDM, styrene butyrene rubber (SBR), fluorine rubber, various copolymers and the like may be used.
본 발명의 일 실시예에 따라 상기 첨가제를 포함하는 리튬 이차전지는, 이차전지의 성능을 확보하고자 포메이션(formation) 및 에이징(aging) 공정을 거칠 수 있다.According to an embodiment of the present invention, the lithium secondary battery including the additive may undergo a formation and aging process to secure the performance of the secondary battery.
포메이션(formation) 공정은 전지 조립 후 충전과 방전을 되풀이하여 전지를 활성화하는 것으로, 충전시 양극으로 사용되는 리튬 금속 산화물로부터 나온 리튬 이온이 음극으로 사용되는 카본 전극으로 이동하여 삽입되는데, 이때 리튬은 반응성이 강하므로 카본 음극과 반응하여 Li2CO3, LiO, LiOH 등의 화합물을 만들어내고, 이것들은 음극 표면에 고체 전해질 계면(solid electrolyte interface: SEI) 피막을 형성하게 된다. 또한, 에이징(aging) 공정은 상기와 같이 활성화된 전지를 일정기간 방치함으로써 안정화시키는 것이다. The formation process is to activate the battery by repeatedly charging and discharging the battery after assembling the battery. Lithium ions from the lithium metal oxide used as the anode during charging are moved to the carbon electrode used as the cathode, where lithium Due to its high reactivity, it reacts with the carbon anode to form compounds such as Li 2 CO 3 , LiO, LiOH, and these form a solid electrolyte interface (SEI) film on the surface of the cathode. In addition, the aging process is to stabilize the battery activated as described above for a certain period of time.
상기 포메이션 공정을 통해 음극 표면에 SEI 막이 형성되는데, 이 SEI 막은 상온 에이징 공정, 즉 상온에서 일정 기간 방치함으로써 안정화되는 것이 일반적이었다. 본 발명의 일 실시예에 따른 첨가제를 포함하는 비수전액을 이용한 리튬 이차전지는, 상온 에이징 공정 뿐만 아니라, 고온 에이징 공정을 거치는 경우에도 리튬과 동족 원소인 Cs, Rb에 의하여, 고온에 의한 SEI 막의 안정성 감소 또는 이의 분해 등의 문제가 발생하지 않는다는 것을 확인할 수 있다. The SEI film is formed on the surface of the cathode through the formation process, and the SEI film is generally stabilized by standing at room temperature for a certain period of time, that is, at room temperature. Lithium secondary battery using a non-aqueous liquid containing an additive according to an embodiment of the present invention, not only at room temperature aging process, but also at a high temperature aging process by the Cs, Rb which is the cognate element of lithium, It can be seen that there is no problem such as reduced stability or decomposition thereof.
상기 포메이션 단계는 특별히 제한하지 않으며, 1.0 ~ 3.8V에서 반충전하거나 또는 3.8 ~ 4.3V에서 만충전할 수 있다. 또한, C-RATE가 0.1C~2C의 전류 밀도로 5 분 내지 1시간 정도 충전하는 것일 수 있다.The formation step is not particularly limited and may be half charged at 1.0 to 3.8V or full charge at 3.8 to 4.3V. In addition, the C-RATE may be charged for 5 minutes to 1 hour at a current density of 0.1C ~ 2C.
상기 에이징 단계는 상온에서 또는 60 내지 100℃의 온도 범위(고온)에서 수행될 수 있다. 상기 온도가 100℃를 초과하는 경우 전해액의 증발로 인해 외장재가 파열되거나 전지가 발화될 가능성이 있다. 또한, 전지의 잔존 용량(SOC)은 전지가 만충전된 상태인 100% 부터 방전으로 인한 0% 까지 어느 범위라도 무방하다. 또한, 저장 시간은 특별한 제한이 없으나, 1시간 내지 1주일 정도가 바람직하다.The aging step may be carried out at room temperature or in a temperature range (high temperature) of 60 to 100 ℃. If the temperature exceeds 100 ° C., there is a possibility that the packaging material may rupture or the battery may ignite due to evaporation of the electrolyte. In addition, the remaining capacity SOC of the battery may be in any range from 100% when the battery is fully charged to 0% due to discharge. In addition, the storage time is not particularly limited, but is preferably about 1 hour to 1 week.
본 발명의 일 실시예에 따른 리튬 이차 전지의 외형은 특별한 제한이 없으나, 캔을 사용한 원통형, 각형, 파우치 (pouch)형 또는 코인 (coin)형 등이 될 수 있다.The external shape of the lithium secondary battery according to an embodiment of the present invention is not particularly limited, but may be cylindrical, rectangular, pouch type, or coin type using a can.
이하, 본 발명을 구체적으로 설명하기 위해 실시예를 들어 상세하게 설명하기로 한다. 그러나, 본 발명에 따른 실시예는 여러 가지 다른 형태로 변형될 수 있으며, 본 발명의 범위가 아래에서 상술하는 실시예에 한정되는 것으로 해석되어서는 안 된다. 본 발명의 실시예는 당업계에서 평균적인 지식을 가진 자에게 본 발명을 보다 완전하게 설명하기 위해서 제공되는 것이다.Hereinafter, the present invention will be described in detail with reference to Examples. However, embodiments according to the present invention can be modified in many different forms, the scope of the present invention should not be construed as limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.
실시예 및 비교예Examples and Comparative Examples
실시예 1Example 1
[전해액의 제조]Preparation of Electrolyte
에틸렌 카보네이트(EC): 에틸메틸 카보네이트(EMC): 디에틸 카보네이트(DEC) =30:50:20 (부피비)의 조성을 갖는 비수성 유기 용매, 리튬염으로서 LiPF6를 비수성 전해액 총량을 기준으로 1.15 mole/l 첨가하고, 첨가제로서 비수성 전해액 총량을 기준으로 세슘 비스(트리플루오로메탄설포닐)이미드 0.5 중량%을 첨가하여 비수성 전해액을 제조하였다.Ethylene carbonate (EC): ethylmethyl carbonate (EMC): diethyl carbonate (DEC) = 30:50:20 (volume ratio) A non-aqueous organic solvent, LiPF 6 as a lithium salt based on the total amount of the non-aqueous electrolyte solution 1.15 mole / l was added, and 0.5 wt% of cesium bis (trifluoromethanesulfonyl) imide was added based on the total amount of the non-aqueous electrolyte solution to prepare a non-aqueous electrolyte solution.
[리튬 이차 전지의 제조][Manufacture of Lithium Secondary Battery]
양극 활물질로서 Li(Ni0.5Co0.2Mn0.3)O2 92 중량%, 도전제로 카본 블랙(carbon black) 4 중량%, 바인더로 폴리비닐리덴 플루오라이드(PVdF) 4 중량%를 용매인 N-메틸-2-피롤리돈(NMP)에 첨가하여 양극 혼합물 슬러리를 제조하였다. 상기 양극 혼합물 슬러리를 두께가 20㎛ 정도의 양극 집전체인 알루미늄(Al) 박막에 도포하고, 건조하여 양극을 제조한 후, 롤 프레스(roll press)를 실시하여 양극을 제조하였다.Li (Ni 0.5 Co 0.2 Mn 0.3 ) O 2 as a positive electrode active material 92% by weight, 4% by weight of carbon black as a conductive agent, 4% by weight of polyvinylidene fluoride (PVdF) as a binder was added to the solvent N-methyl-2-pyrrolidone (NMP) to slurry the positive electrode mixture. Was prepared. The positive electrode mixture slurry was applied to a thin film of aluminum (Al), which is a positive electrode current collector having a thickness of about 20 μm, dried to prepare a positive electrode, and then subjected to roll press to prepare a positive electrode.
또한, 음극 활물질로 탄소 분말, 바인더로 PVdF, 도전제로 카본 블랙(carbon black)을 각각 96 중량%, 3 중량% 및 1 중량%로 하여 용매인 NMP에 첨가하여 음극 혼합물 슬러리를 제조하였다. 상기 음극 혼합물 슬러리를 두께가 10㎛의 음극 집전체인 구리(Cu) 박막에 도포하고, 건조하여 음극을 제조한 후, 롤 프레스(roll press)를 실시하여 음극을 제조하였다.Further, a negative electrode mixture slurry was prepared by adding carbon powder as a negative electrode active material, PVdF as a binder, and carbon black as a conductive agent at 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as a solvent. The negative electrode mixture slurry was applied to a copper (Cu) thin film, which is a negative electrode current collector having a thickness of 10 μm, dried to prepare a negative electrode, and then roll-rolled to prepare a negative electrode.
이와 같이 제조된 양극과 음극을 폴리프로필렌/폴리에틸렌/폴리프로필렌 (PP/PE/PP) 3층으로 이루어진 분리막과 함께 통상적인 방법으로 파우치형 전지를 제작 후, 제조된 상기 비수성 전해액을 주액하여 리튬 이차 전지의 제조를 완성하였다.After preparing a pouch-type battery in a conventional manner with a separator consisting of a polypropylene / polyethylene / polypropylene (PP / PE / PP) three layers of the positive electrode and the negative electrode prepared in this way, the prepared non-aqueous electrolyte solution by pouring lithium The manufacture of a secondary battery was completed.
실시예 2Example 2
상기 첨가제로서 세슘 비스(트리플루오로메탄설포닐)이미드의 함량을 비수성 전해액 총량을 기준으로 0.7 중량% 첨가한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 0.7 wt% of cesium bis (trifluoromethanesulfonyl) imide was added as the additive to 0.7 wt% based on the total amount of the non-aqueous electrolyte. It was.
실시예 3Example 3
상기 첨가제로서 세슘 비스(트리플루오로메탄설포닐)이미드의 함량을 비수성 전해액 총량을 기준으로 1 중량% 첨가한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.A nonaqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 1 wt% of cesium bis (trifluoromethanesulfonyl) imide was added as the additive based on the total amount of the nonaqueous electrolyte. It was.
실시예 4Example 4
상기 첨가제로서 세슘 비스(트리플루오로메탄설포닐)이미드의 함량을 비수성 전해액 총량을 기준으로 3 중량% 첨가한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 3 wt% of cesium bis (trifluoromethanesulfonyl) imide was added as the additive based on the total amount of the non-aqueous electrolyte solution. It was.
실시예 5Example 5
상기 첨가제로서 세슘 비스(트리플루오로메탄설포닐)이미드 대신 세슘 니트레이트를 0.5 중량% 이용한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차전지를 제조하였다.A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that cesium nitrate was used in an amount of 0.5% by weight instead of cesium bis (trifluoromethanesulfonyl) imide.
실시예 6Example 6
상기 첨가제로서 세슘 비스(트리플루오로메탄설포닐)이미드 대신 세슘 니트레이트를 0.7 중량% 이용한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차전지를 제조하였다.A nonaqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 0.7 wt% of cesium nitrate was used instead of cesium bis (trifluoromethanesulfonyl) imide as the additive.
실시예 7Example 7
상기 첨가제 세슘 비스(트리플루오로메탄설포닐)이미드 대신 세슘 니트레이트를 1.0 중량% 이용한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차전지를 제조하였다.A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that 1.0 wt% of cesium nitrate was used instead of the cesium bis (trifluoromethanesulfonyl) imide.
실시예 8Example 8
상기 첨가제 세슘 비스(트리플루오로메탄설포닐)이미드 대신 세슘 니트레이트를 3.0 중량% 이용한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차전지를 제조하였다.A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 3.0 wt% of cesium nitrate was used instead of the cesium bis (trifluoromethanesulfonyl) imide.
실시예 9Example 9
상기 첨가제로서 세슘 비스(트리플루오로메탄설포닐)이미드 대신 루비듐 비스(트리플루오로메탄설포닐)이미드를 0.5 중량% 이용한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차전지를 제조하였다.A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 0.5 wt% of rubidium bis (trifluoromethanesulfonyl) imide was used instead of cesium bis (trifluoromethanesulfonyl) imide as the additive. The battery was prepared.
실시예 10Example 10
상기 첨가제로서 세슘 비스(트리플루오로메탄설포닐)이미드 대신 루비듐 니트레이트를 0.5 중량% 이용한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차전지를 제조하였다.A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that 0.5 wt% of rubidium nitrate was used instead of cesium bis (trifluoromethanesulfonyl) imide as the additive.
실시예 11Example 11
상기 첨가제로서 세슘 비스(트리플루오로메탄설포닐)이미드의 함량을 비수성 전해액 총량을 기준으로 0.5 중량% 및 리튬 디플루오로 비스옥살레이토 포스페이트의 함량을 0.5 중량% 첨가한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.It was carried out except that the content of cesium bis (trifluoromethanesulfonyl) imide as the additive was 0.5% by weight based on the total amount of the non-aqueous electrolyte and 0.5% by weight of the lithium difluoro bisoxalato phosphate. In the same manner as in Example 1, a nonaqueous electrolyte solution and a lithium secondary battery were prepared.
실시예 12Example 12
상기 첨가제로서 세슘 비스(트리플루오로메탄설포닐)이미드 대신 세슘 니트레이트의 함량을 비수성 전해액 총량을 기준으로 0.5 중량% 및 리튬 디플루오로 비스옥살레이토 포스페이트의 함량을 0.5 중량% 첨가한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.Cesium nitrate instead of cesium bis (trifluoromethanesulfonyl) imide as the additive was added 0.5% by weight based on the total amount of the non-aqueous electrolyte and 0.5% by weight of the lithium difluoro bisoxalatophosphate. A nonaqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except for the above.
실시예 13Example 13
상기 양극 활물질을 Li[Ni1/3Co1/3Mn1/3]O2로 이용한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the cathode active material was used as Li [Ni 1/3 Co 1/3 Mn 1/3 ] O 2 .
실시예 14Example 14
상기 양극 활물질을 LiCoO2로 이용한 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the positive electrode active material was used as LiCoO 2 .
실시예 15Example 15
상기 비수성 전해액에 세슘 비스(트리플루오로메탄설포닐)이미드 첨가제를 0.03 중량%로 넣은 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.A nonaqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that cesium bis (trifluoromethanesulfonyl) imide additive was added at 0.03% by weight in the nonaqueous electrolyte solution.
실시예 16Example 16
상기 비수성 전해액에 세슘 비스(트리플루오로메탄설포닐)이미드 첨가제를 11 중량%로 넣은 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.Cesium bis (trifluoromethanesulfonyl) imide in the non-aqueous electrolyte A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the additive was added in an amount of 11 wt%.
실시예 17Example 17
상기 비수성 전해액에 세슘 비스(트리플루오로메탄설포닐)이미드 대신 세슘 니트레이트 첨가제를 0.03 중량%로 넣은 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.Cesium nitrate instead of cesium bis (trifluoromethanesulfonyl) imide in the non-aqueous electrolyte A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the additive was added at 0.03% by weight.
실시예 18Example 18
상기 비수성 전해액에 세슘 비스(트리플루오로메탄설포닐)이미드 대신 세슘 니트레이트 첨가제를 11 중량%로 넣은 것을 제외하고는 실시예 1과 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.Cesium nitrate instead of cesium bis (trifluoromethanesulfonyl) imide in the non-aqueous electrolyte A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1 except that the additive was added in an amount of 11 wt%.
실험 및 평가Experiment and evaluation
고온 수명 평가High temperature life rating
상기 리튬 이차전지를 고온(45℃)에서 1.5C rate의 전류로 전압이 4.20V(vs. Li) 에 이를 때까지 정전류 충전하고, 이어서 정전압 모드에서 4.20V를 유지하면서 0.05C rate의 전류에서 컷오프 (cut-off)하였다. 이어서, 방전시에 전압이 3.0V(vs. Li)에 이를 때까지 1.5C rate의 정전류로 방전하였다(1st 사이클). 상기와 같은 사이클을 300회 사이클까지 반복 하였다. 상기 실험 결과를 표 1 및 표 2에 나타내었다. The lithium secondary battery is charged at a constant current until the voltage reaches 4.20 V (vs. Li) at a high temperature (45 ° C.) at a current of 1.5 C, and then cuts off at a current of 0.05 C at a constant voltage mode while maintaining 4.20 V. (cut-off). Subsequently, discharge was performed at a constant current of 1.5 C rate (1st cycle) until the voltage reached 3.0 V (vs. Li). The same cycle was repeated up to 300 cycles. The experimental results are shown in Table 1 and Table 2.
비고Remarks 고온 수명 특성High temperature life characteristics
최초 사이클 용량(mAh)First cycle capacity (mAh) 300째 사이클 용량(mAh)300th cycle capacity (mAh) 용량유지율(%)300째 용량/초기용량*100(%)Capacity maintenance rate (%) 300th capacity / initial capacity * 100 (%)
실시예 1Example 1 911.2911.2 644.31644.31 70.7170.71
실시예 2Example 2 910.74910.74 638.70638.70 70.1370.13
실시예 3Example 3 910.09910.09 632.60632.60 69.5169.51
실시예 4Example 4 898.21898.21 612.04612.04 68.1468.14
실시예 5Example 5 908.49908.49 634.94634.94 69.8969.89
실시예 6Example 6 907.89907.89 628.35628.35 69.2169.21
실시예 7Example 7 907.18907.18 619.97619.97 68.3468.34
실시예 8Example 8 905.63905.63 608.22608.22 67.1667.16
실시예 9Example 9 902.15902.15 624.38624.38 69.2169.21
실시예 10Example 10 901.24901.24 615.01615.01 68.2468.24
실시예 11Example 11 912.13912.13 644.69644.69 70.6870.68
실시예 12Example 12 908.29908.29 635.62635.62 69.9869.98
실시예 13Example 13 912.13912.13 636.76636.76 69.8169.81
실시예 14Example 14 908.29908.29 623.81623.81 68.6868.68
비고Remarks 고온 수명 특성High temperature life characteristics
최초 사이클 용량(mAh)First cycle capacity (mAh) 300째 사이클 용량(mAh)300th cycle capacity (mAh) 용량유지율(%)300째 용량/초기용량*100(%)Capacity maintenance rate (%) 300th capacity / initial capacity * 100 (%)
실시예 15Example 15 907.97907.97 546.42546.42 60.1860.18
실시예 16Example 16 889.23889.23 501.08501.08 56.3556.35
실시예 17Example 17 908.31908.31 544.35544.35 59.9359.93
실시예 18Example 18 884.23884.23 480.58480.58 54.3554.35
저온 수명 평가Low temperature life assessment
상기 리튬 이차전지를 상온(25℃)-저온(-10℃)-저온(-20℃)-상온(25℃)에서 0.5C rate의 전류로 전압이 4.20V(vs. Li) 에 이를 때까지 정전류 충전하고, 이어서 정전압 모드에서 4.20V를 유지하면서 0.05C rate의 전류에서 컷오프 (cut-off)하였다. 이어서, 방전시에 전압이 3.0V(vs. Li)에 이를 때까지 0.5C rate의 정전류로 방전하였다(1st 사이클). 상기와 같은 사이클 각 온도별로 순차적으로 10회 반복하였다. 10회 반복 후의 마지막 사이클 째에서의 용량을 측정하고, 상기 모든 사이클이 종료(상온(25℃)-저온(-10℃)-저온(-20℃)-상온(25℃))된 후의 최후의 사이클째 용량을 측정하여 용량 유지율을 계산하였다. 상기 충방전 실험 결과를 표 3 및 표 4에 나타내었다. The lithium secondary battery was operated at room temperature (25 ° C) -low temperature (-10 ° C) -low temperature (-20 ° C) -room temperature (25 ° C) at a current of 0.5C rate until the voltage reached 4.20V (vs. Li). Constant current charge was then cut-off at a current of 0.05 C rate while maintaining 4.20 V in constant voltage mode. Subsequently, it discharged at the constant current of 0.5 C rate (1st cycle) until the voltage reached 3.0V (vs. Li) at the time of discharge. The cycle was repeated 10 times in sequence for each temperature. The capacity at the last cycle after 10 iterations is measured and the last after all the cycles are finished (room temperature (25 ° C.)-Low temperature (-10 ° C.)-Low temperature (-20 ° C.)-Room temperature (25 ° C.)). Dose retention was calculated by measuring the dose at cycle. The charge and discharge test results are shown in Tables 3 and 4.
비고Remarks 저온 수명 특성Low temperature life characteristics
상온 사이클 용량(mAh)Room temperature cycle capacity (mAh) -10℃ 사이클 용량(mAh)-10 ° C cycle capacity (mAh) -20℃ 사이클 용량(mAh)-20 ℃ cycle capacity (mAh) 저온평가 후 상온 사이클 용량(mAh)Room temperature cycle capacity (mAh) after low temperature evaluation 용량유지율(%)저온평가 후 상온 용량/초기 상온 용량*100(%)Capacity retention rate (%) Normal temperature capacity after initial low temperature evaluation / initial room temperature capacity * 100 (%)
실시예 1Example 1 899.25899.25 536.72536.72 218.85218.85 415.82415.82 46.2446.24
실시예 2Example 2 898.16898.16 534.12534.12 217.5217.5 413.17413.17 46.0046.00
실시예 3Example 3 897.84897.84 532.48532.48 216.82216.82 411.15411.15 45.7945.79
실시예 4Example 4 896.68896.68 529.28529.28 214.96214.96 405.29405.29 45.2045.20
실시예 5Example 5 896.81896.81 533.18533.18 215.18215.18 412.3412.3 45.9745.97
실시예 6Example 6 895.18895.18 531.84531.84 214.79214.79 407.17407.17 45.4845.48
실시예 7Example 7 893.37893.37 529.76529.76 213.14213.14 402.23402.23 45.0245.02
실시예 8Example 8 890.19890.19 526.27526.27 211.41211.41 399.41399.41 44.8744.87
실시예 9Example 9 890.84890.84 527.18527.18 208.24208.24 405.74405.74 45.5545.55
실시예 10Example 10 887.21887.21 526.87526.87 206.74206.74 401.84401.84 45.2945.29
실시예 11Example 11 900.84900.84 537.86537.86 219.72219.72 416.62416.62 46.2546.25
실시예 12Example 12 897.75897.75 534.74534.74 216.71216.71 413.21413.21 46.0346.03
실시예 13Example 13 898.54898.54 532.18532.18 216.48216.48 413.96413.96 46.0746.07
실시예 14Example 14 896.43896.43 530.26530.26 214.86214.86 411.52411.52 45.9145.91
비고Remarks 저온 수명 특성Low temperature life characteristics
상온 사이클 용량(mAh)Room temperature cycle capacity (mAh) -10℃ 사이클 용량(mAh)-10 ° C cycle capacity (mAh) -20℃ 사이클 용량(mAh)-20 ℃ cycle capacity (mAh) 저온평가 후 상온 사이클 용량(mAh)Room temperature cycle capacity (mAh) after low temperature evaluation 용량유지율(%)저온평가 후 상온 용량/초기 상온 용량*100(%)Capacity retention rate (%) Normal temperature capacity after initial low temperature evaluation / initial room temperature capacity * 100 (%)
실시예 15Example 15 896.96896.96 363.06363.06 111.68111.68 285.82285.82 31.8731.87
실시예 16Example 16 889.19889.19 353.45353.45 104.18104.18 272.14272.14 30.6130.61
실시예 17Example 17 895.86895.86 361.06361.06 110.2110.2 283.13283.13 31.6031.60
실시예 18Example 18 887.52887.52 352.13352.13 102.23102.23 270.17270.17 30.4430.44
60℃ 저장 특성60 ℃ storage characteristics
25℃로 유지되는 챔버 내에 실시예 및 비교예의 이차전지를 배치하고, 충방전기를 이용하여 다음과 같이 충방전 시험을 하였다. 먼저, 1C로 SOC(state of charge)의 60%까지 충전한 후 0.2C로 10초 동안 방전/충전 시켰다. 그 다음, 0.5C로 10초 동 안 방전/충전 시켰다. 그 이후 다음 순서로 동일하게 1C, 2C, 3C로 10초동안 방전 충전 시켰다. 마지막으로, 0.5C로 4.2V까지 충전하였다. 0.2C, 0.5C, 1C, 2C, 3C 방전 후의 전압값을 이용하여 전압 대 전류 그래프의 추 세선의 기울기를 계산하여 초기 임피던스(DC-IR)를 구했다. 초기 임피던스를 측정한 상기 전지를, 60℃로 유지되는 챔버 내에 넣고 4주(매주 측정하여 4주차까지 측정)하였으며, 임피던스(DC-IR)를 계산하였다. 그 결과를 표 5 및 표 6에 나타내었다.Secondary batteries of Examples and Comparative Examples were placed in a chamber maintained at 25 ° C., and a charge / discharge test was performed using a charger / discharger as follows. First, the battery was charged to 60% of SOC (state of charge) at 1 C and then discharged / charged at 0.2 C for 10 seconds. Then, it was discharged / charged at 0.5C for 10 seconds. After that, the charge was discharged for 10 seconds to 1C, 2C, 3C in the same order. Finally, it charged to 4.2V at 0.5C. Using the voltage values after 0.2C, 0.5C, 1C, 2C, and 3C discharge, the slope of the trend line of the voltage-to-current graph was calculated to determine the initial impedance (DC-IR). The battery, which measured the initial impedance, was placed in a chamber maintained at 60 ° C. for 4 weeks (measured weekly to 4 weeks), and impedance (DC-IR) was calculated. The results are shown in Tables 5 and 6.
비고Remarks 저장 특성Storage properties
초기 임피던스(mΩ)Initial Impedance (mΩ) 60℃ 저장 후 임피던스(mΩ) (4W 후)Impedance after storage at 60 ℃ (m 저장) (after 4W) 변화율(%)60℃후(mΩ)/초기(mΩ)*100(%)Rate of change (%) After 60 ° C (mΩ) / Initial (mΩ) * 100 (%)
실시예 1Example 1 47.547.5 7979 166.32166.32
실시예 2Example 2 47.847.8 80.680.6 168.62168.62
실시예 3Example 3 48.448.4 81.981.9 169.21169.21
실시예 4Example 4 50.150.1 85.685.6 170.86170.86
실시예 5Example 5 48.448.4 8484 173.55173.55
실시예 6Example 6 48.948.9 85.185.1 174.03174.03
실시예 7Example 7 49.849.8 87.487.4 175.50175.50
실시예 8Example 8 51.451.4 91.791.7 178.40178.40
실시예 9Example 9 48.148.1 81.181.1 168.61168.61
실시예 10Example 10 50.150.1 87.587.5 174.65174.65
실시예 11Example 11 47.247.2 78.878.8 166.95166.95
실시예 12Example 12 48.148.1 83.483.4 173.39173.39
실시예 13Example 13 47.947.9 80.880.8 168.68168.68
실시예 14Example 14 48.248.2 82.182.1 170.33170.33
비고Remarks 저장 특성Storage properties
초기 임피던스(mΩ)Initial Impedance (mΩ) 60℃ 저장 후 임피던스(mΩ) (4W 후)Impedance after storage at 60 ℃ (m 저장) (after 4W) 변화율(%)60℃후(mΩ)/초기(mΩ)*100(%)Rate of change (%) After 60 ° C (mΩ) / Initial (mΩ) * 100 (%)
실시예 15Example 15 43.143.1 82.282.2 190.72190.72
실시예 16Example 16 45.545.5 90.690.6 199.12199.12
실시예 17Example 17 42.942.9 82.482.4 192.07192.07
실시예 18Example 18 46.146.1 92.592.5 200.65200.65
두께 변화율 측정Thickness change rate measurement
상기 실시예 및 비교예에서 제조된 이차전지의 두께 변화율을 알아보기 위해 하기와 같은 실험을 수행하였다. In order to determine the rate of change of the thickness of the secondary battery manufactured in Examples and Comparative Examples, the following experiment was performed.
리튬 이차전지의 수명 특성은 첫번째 사이클은 0.1C로 충방전을 수행하고, 이후 사이클은 0.5C로 충방전을 실시하였다. 두께 변화율은 300번째 사이클의 충전 상태에서 리튬 이차전지를 각각 분해하여 전극 두께를 측정한 후 첫번째 사이클 전의 전극 두께와 비교하였다. 결과를 표 7 및 표 8에 나타내었다.As for the life characteristics of the lithium secondary battery, the first cycle was charged and discharged at 0.1C, and the subsequent cycle was charged and discharged at 0.5C. The thickness change rate was compared with the electrode thickness before the first cycle after disassembling each of the lithium secondary batteries in the state of charge of the 300th cycle and measuring the electrode thickness. The results are shown in Tables 7 and 8.
-두께 변화율: 300번째 사이클의 충전 상태에서의 전극 두께-첫번째 사이클 전의 전극 두께)/첫번째 사이클 전의 전극 두께×100Thickness change rate: electrode thickness at 300th cycle of charge state-electrode thickness before first cycle) / electrode thickness before first cycle x 100
비고Remarks 두께 변화율(%)Thickness change rate (%)
실시예 1Example 1 107.24107.24
실시예 2Example 2 107.66107.66
실시예 3Example 3 108.18108.18
실시예 4Example 4 109.14109.14
실시예 5Example 5 108.53108.53
실시예 6Example 6 108.75108.75
실시예 7Example 7 109.09109.09
실시예 8Example 8 110.24110.24
실시예 9Example 9 108.19108.19
실시예 10Example 10 109.23109.23
실시예 11Example 11 108.36108.36
실시예 12Example 12 109.98109.98
실시예 13Example 13 108.96108.96
실시예 14Example 14 108.78108.78
비고Remarks 두께 변화율(%)Thickness change rate (%)
실시예 15Example 15 113.21113.21
실시예 16Example 16 117.25117.25
실시예 17Example 17 114.12114.12
실시예 18Example 18 118.29118.29
상기 표에서 확인 할 수 있는 바와 같이, 본 발명의 실시예의 이차전지가 비교예에 비해 이차전지 보다 고온, 저온 수명 특성, 고온저장 특성, 및 두께 변화율에 있어 전반적으로 현저히 우수함을 확인 할 수 있었다.As can be seen in the above table, it was confirmed that the secondary battery of the embodiment of the present invention is significantly superior to the secondary battery in terms of high temperature, low temperature life characteristics, high temperature storage characteristics, and thickness change rates in comparison with the comparative examples.
실시예 19Example 19
[전해액의 제조]Preparation of Electrolyte
에틸렌 카보네이트(EC): 에틸메틸 카보네이트(EMC): 디에틸 카보네이트(DEC) =30:50:20 (부피비)의 조성을 갖는 비수성 유기 용매, 리튬염으로서 LiPF6를 비수성 전해액 총량을 기준으로 1.15 mole/l 첨가하고, 첨가제로서 비수성 전해액 총량을 기준으로 세슘 비스(트리플루오로메탄설포닐)이미드 0.5 중량% 및 리튬 디플루오로 비스옥살레이토 포스페이트 1 중량%(중량비 1 : 2)를 첨가하여 비수성 전해액을 제조하였다.Ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) = 30:50:20 (volume ratio) A non-aqueous organic solvent, LiPF 6 as a lithium salt based on the total amount of the non-aqueous electrolyte solution 1.15 mole / l was added, and 0.5% by weight of cesium bis (trifluoromethanesulfonyl) imide and 1% by weight of lithium difluoro bisoxalatophosphate (weight ratio 1: 2) were added as a additive based on the total amount of the non-aqueous electrolyte solution. To prepare a non-aqueous electrolyte solution.
[리튬 이차 전지의 제조][Manufacture of Lithium Secondary Battery]
양극 활물질로서 Li(Ni0.5Co0.2Mn0.3)O2 92 중량%, 도전제로 카본 블랙(carbon black) 4 중량%, 바인더로 폴리비닐리덴 플루오라이드(PVdF) 4 중량%를 용매인 N-메틸-2-피롤리돈(NMP)에 첨가하여 양극 혼합물 슬러리를 제조하였다. 상기 양극 혼합물 슬러리를 두께가 20㎛ 정도의 양극 집전체인 알루미늄(Al) 박막에 도포하고, 건조하여 양극을 제조한 후, 롤 프레스(roll press)를 실시하여 양극을 제조하였다.Li (Ni 0.5 Co 0.2 Mn 0.3 ) O 2 as a positive electrode active material 92% by weight, 4% by weight of carbon black as a conductive agent, 4% by weight of polyvinylidene fluoride (PVdF) as a binder was added to the solvent N-methyl-2-pyrrolidone (NMP) to slurry the positive electrode mixture. Was prepared. The positive electrode mixture slurry was applied to a thin film of aluminum (Al), which is a positive electrode current collector having a thickness of about 20 μm, dried to prepare a positive electrode, and then subjected to roll press to prepare a positive electrode.
또한, 음극 활물질로 탄소 분말, 바인더로 PVdF, 도전제로 카본 블랙(carbon black)을 각각 96 중량%, 3 중량% 및 1 중량%로 하여 용매인 NMP에 첨가하여 음극 혼합물 슬러리를 제조하였다. 상기 음극 혼합물 슬러리를 두께가 10㎛의 음극 집전체인 구리(Cu) 박막에 도포하고, 건조하여 음극을 제조한 후, 롤 프레스(roll press)를 실시하여 음극을 제조하였다.Further, a negative electrode mixture slurry was prepared by adding carbon powder as a negative electrode active material, PVdF as a binder, and carbon black as a conductive agent at 96 wt%, 3 wt%, and 1 wt%, respectively, to NMP as a solvent. The negative electrode mixture slurry was applied to a copper (Cu) thin film, which is a negative electrode current collector having a thickness of 10 μm, dried to prepare a negative electrode, and then roll-rolled to prepare a negative electrode.
이와 같이 제조된 양극과 음극을 폴리프로필렌/폴리에틸렌/폴리프로필렌 (PP/PE/PP) 3층으로 이루어진 분리막과 함께 통상적인 방법으로 파우치형 전지를 제작 후, 제조된 상기 비수성 전해액을 주액하여 리튬 이차 전지의 제조를 완성하였다.After preparing a pouch-type battery in a conventional manner with a separator consisting of a polypropylene / polyethylene / polypropylene (PP / PE / PP) three layers of the positive electrode and the negative electrode prepared in this way, the prepared non-aqueous electrolyte solution by pouring lithium The manufacture of a secondary battery was completed.
실시예 20Example 20
상기 전해액 첨가제로서, 세슘 비스(트리플루오로메탄설포닐)이미드 0.5 중량% 및 리튬 디플루오로 비스옥살레이토 포스페이트 0.5 중량%(중량비 1 : 1)를 포함하는 것을 제외하고는 실시예 19와 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.Same as Example 19, except that the electrolyte solution additive contained 0.5 wt% cesium bis (trifluoromethanesulfonyl) imide and 0.5 wt% lithium difluoro bisoxalatophosphate (weight ratio 1: 1). A nonaqueous electrolyte solution and a lithium secondary battery were prepared.
실시예 21Example 21
상기 전해액 첨가제로서, 세슘 비스(트리플루오로메탄설포닐)이미드 0.5 중량% 및 리튬 디플루오로 비스옥살레이토 포스페이트 2 중량%(중량비 1 : 4)를 포함하는 것을 제외하고는 실시예 19와 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.Same as Example 19, except that 0.5 wt% cesium bis (trifluoromethanesulfonyl) imide and 2 wt% lithium difluoro bisoxalato phosphate (weight ratio 1: 4) were included as the electrolyte additive. A nonaqueous electrolyte solution and a lithium secondary battery were prepared.
실시예 22Example 22
상기 전해액 첨가제로서, 루비듐 비스(트리플루오로메탄설포닐)이미드 0.5 중량% 및 리튬 디플루오로 비스옥살레이토 포스페이트 1 중량%(중량비 1 : 2)를 포함하는 것을 제외하고는 실시예 19와 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.Same as Example 19, except that 0.5 wt% of rubidium bis (trifluoromethanesulfonyl) imide and 1 wt% of lithium difluoro bisoxalato phosphate (weight ratio 1: 2) were included as the electrolyte additive. A nonaqueous electrolyte solution and a lithium secondary battery were prepared.
실시예 23Example 23
상기 전해액 첨가제로서, 세슘 비스(트리플루오로메탄설포닐)이미드 0.5 중량% 및 리튬 디플루오로 비스옥살레이토 포스페이트 0.25 중량%(중량비 1 : 0.5)를 포함하는 것을 제외하고는 실시예 19와 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.Same as Example 19, except that the electrolyte solution additive contained 0.5 wt% cesium bis (trifluoromethanesulfonyl) imide and 0.25 wt% lithium difluoro bisoxalato phosphate (weight ratio 1: 0.5) A nonaqueous electrolyte solution and a lithium secondary battery were prepared.
실시예 24Example 24
상기 전해액 첨가제로서, 세슘 비스(트리플루오로메탄설포닐)이미드 0.5 중량% 및 리튬 디플루오로 비스옥살레이토 포스페이트 2.25 중량%(중량비 1 : 4.5)를 포함하는 것을 제외하고는 실시예 19와 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.Same as Example 19, except that the electrolyte solution additive contained 0.5 wt% cesium bis (trifluoromethanesulfonyl) imide and 2.25 wt% lithium difluoro bisoxalato phosphate (weight ratio 1: 4.5). A nonaqueous electrolyte solution and a lithium secondary battery were prepared.
실시예 25Example 25
상기 전해액 첨가제로서, 세슘 비스(플루오로설포닐)이미드 0.5 중량% 및 리튬 디플루오로 비스옥살레이토 포스페이트 0.5 중량%(중량비 1 : 1)를 포함하는 것을 제외하고는 실시예 19와 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.In the same manner as in Example 19, except that the electrolyte solution additive contained 0.5 wt% cesium bis (fluorosulfonyl) imide and 0.5 wt% lithium difluoro bisoxalato phosphate (weight ratio 1: 1). A nonaqueous electrolyte solution and a lithium secondary battery were prepared.
비교예 1Comparative Example 1
상기 전해액 첨가제로서, 세슘 비스(트리플루오로메탄설포닐)이미드 0.5 중량% 및 감마 부티로 락톤(gamma butylo lacton: GBL)을 0.5 중량%(중량비 1 : 1)를 포함하는 것을 제외하고는 실시예 15와 동일하게 하여 비수성 전해액 및 리튬 이차 전지를 제조하였다.As the electrolyte solution additive, 0.5 wt% cesium bis (trifluoromethanesulfonyl) imide and 0.5 wt% (gamma butylo lacton: GBL) were carried out except that they contained 0.5 wt% (weight ratio 1: 1). In the same manner as in Example 15, a nonaqueous electrolyte solution and a lithium secondary battery were prepared.
고온 출력 특성 평가High Temperature Output Characteristic Evaluation
실시예 1, 실시예 19 내지 실시예 25 및 비교예 1의 리튬 이차 전지를 60℃에서 저장 후, SOC 50%에서 5C로 10초간 방전하여 발생하는 전압차로 출력을 계산하였다. 그 결과를 도 1에 나타낸다.The lithium secondary batteries of Example 1, Examples 19 to 25, and Comparative Example 1 were stored at 60 ° C., and then output was calculated using a voltage difference generated by discharging at SOC at 50% for 5 seconds at 50% of SOC. The result is shown in FIG.
도 1을 참조하면, 저장 기간에 상관 없이, 세슘 비스(트리플루오로메탄설포닐)이미드(또는 루비듐 비스(트리플루오로메탄설포닐)이미드, 세슘 비스(플루오로설포닐)이미드) 및 리튬 디플루오로 비스옥살레이토 포스페이트를　소정의 중량비로 동시에 포함한 실시예 19 내지 25의 리튬 이차 전지의 고온 출력이 그렇지 않은 실시예 1, 비교예 1의 고온 출력에 비해 우수함을 알 수 있다. 특히, 저장기간이 7주 이후부터 고온 출력 특성의 차이가 더욱 커짐을 알 수 있다.1, cesium bis (trifluoromethanesulfonyl) imide (or rubidium bis (trifluoromethanesulfonyl) imide, cesium bis (fluorosulfonyl) imide) regardless of storage period And it can be seen that the high temperature output of the lithium secondary batteries of Examples 19 to 25 simultaneously containing lithium difluoro bisoxalato phosphate at a predetermined weight ratio is superior to the high temperature output of Example 1 and Comparative Example 1 that are not. In particular, it can be seen that the difference in high temperature output characteristics becomes greater after 7 weeks of storage.

Claims (17)

  1. 질소 원자 함유 화합물 유래 음이온과 Cs+ 또는 Rb+와의 염을 포함하는 전해액 첨가제.An electrolyte solution additive comprising a salt of an anion derived from a nitrogen atom-containing compound with Cs + or Rb + .
  2. 청구항 1에 있어서,The method according to claim 1,
    상기 질소 원자 함유 화합물 유래 음이온은 아미드계 음이온, 이미드계 음이온, 니트릴계 음이온, 니트리트 음이온, 및 니트레이트 음이온으로 이루어진 군에서 선택되는 1종 이상을 포함하는 것인 전해액 첨가제.The nitrogen-containing compound-derived anion is an electrolyte solution additive comprising one or more selected from the group consisting of amide anions, imide anions, nitrile anions, nitrite anions, and nitrate anions.
  3. 청구항 2에 있어서,The method according to claim 2,
    상기 아미드계 음이온은 디메틸포름아미드 음이온, 디메틸아세트아미드 음이온, 디에틸포름아미드 음이온, 디에틸아세트아미드 음이온, 메틸에틸포름아미드 음이온, 및 메틸에틸아세트아미드 음이온으로 이루어진 군에서 선택되는 1종 이상을 포함하는 것인 전해액 첨가제.The amide anion includes at least one member selected from the group consisting of dimethylformamide anion, dimethylacetamide anion, diethylformamide anion, diethylacetamide anion, methylethylformamide anion, and methylethylacetamide anion. Electrolyte solution additive.
  4. 청구항 2에 있어서,The method according to claim 2,
    상기 이미드계 음이온은 이하 화학식 1로 나타내는 것인 전해액 첨가제.The imide-based anion is an electrolyte solution additive represented by the following formula (1).
    [화학식 1][Formula 1]
    Figure PCTKR2017009758-appb-I000007
    Figure PCTKR2017009758-appb-I000007
    (여기서, R1　및 R2는 각각 플루오로기 또는 탄소수 1 내지 4의 플루오로 알킬기이고, 또는 R1　및 R2는 서로 연결되어 탄소수 1 내지 4의 플루오로 시클로알킬렌(fluoro cycloalkylene) 고리를 형성하여도 된다.)(Wherein R 1 and R 2 are each a fluoro group or a fluoroalkyl group having 1 to 4 carbon atoms, or R 1 and R 2 are connected to each other to form a fluoro cycloalkylene ring having 1 to 4 carbon atoms). May be formed.)
  5. 청구항 2에 있어서,The method according to claim 2,
    상기 니트릴계 음이온은 아세토니트릴 음이온, 프로피오니트릴 음이온, 부티로니트릴 음이온, 발레로니트릴 음이온, 카프릴로니트릴 음이온, 헵탄니트릴 음이온, 싸이클로펜탄 카보니트릴 음이온, 싸이클로헥산 카보니트릴 음이온, 2-플루오로벤조니트릴 음이온, 4-플루오로벤조니트릴 음이온, 다이플루오로벤조니트릴 음이온, 트리플루오로벤조니트릴 음이온, 페닐아세토니트릴 음이온, 2-플루오로페닐아세토니트릴 음이온, 및 4-플루오로페닐아세토니트릴 음이온으로 이루어진 군에서 선택되는 1종 이상을 포함하는 것인 전해액 첨가제.The nitrile anions include acetonitrile anion, propionitrile anion, butyronitrile anion, valeronitrile anion, caprylonitrile anion, heptanenitrile anion, cyclopentane carbonitrile anion, cyclohexane carbonitrile anion, and 2-fluorobenzo Nitrile anion, 4-fluorobenzonitrile anion, difluorobenzonitrile anion, trifluorobenzonitrile anion, phenylacetonitrile anion, 2-fluorophenylacetonitrile anion, and 4-fluorophenylacetonitrile anion Electrolyte additive which contains at least 1 type selected from the group.
  6. 청구항 4에 있어서,The method according to claim 4,
    상기 화학식 1로 나타내는 화합물은 하기 화학식 2 내지 6으로 이루어진 군에서 선택되는 1종 이상을 포함하는 것인 전해액 첨가제.The compound represented by Chemical Formula 1 is an electrolyte solution additive containing one or more selected from the group consisting of the following Chemical Formulas 2 to 6.
    [화학식 2][Formula 2]
    Figure PCTKR2017009758-appb-I000008
    Figure PCTKR2017009758-appb-I000008
    [화학식 3][Formula 3]
    Figure PCTKR2017009758-appb-I000009
    Figure PCTKR2017009758-appb-I000009
    [화학식 4][Formula 4]
    Figure PCTKR2017009758-appb-I000010
    Figure PCTKR2017009758-appb-I000010
    [화학식 5][Formula 5]
    Figure PCTKR2017009758-appb-I000011
    Figure PCTKR2017009758-appb-I000011
    [화학식 6][Formula 6]
    Figure PCTKR2017009758-appb-I000012
    Figure PCTKR2017009758-appb-I000012
  7. 청구항 1에 있어서,The method according to claim 1,
    상기 전해액 첨가제는 세슘 비스(트리플루오로메탄설포닐)이미드, 세슘 니트레이트, 루비듐 비스(트리플루오로메탄설포닐)이미드, 루비듐 니트레이트 및 세슘 비스(플루오로설포닐)이미드로 이루어진 군에서 선택되는 1종 이상을 포함하는 것인 전해액 첨가제.The electrolyte additive is a group consisting of cesium bis (trifluoromethanesulfonyl) imide, cesium nitrate, rubidium bis (trifluoromethanesulfonyl) imide, rubidium nitrate and cesium bis (fluorosulfonyl) imide An electrolyte solution additive comprising one or more selected from.
  8. 청구항 1 내지 7 중 어느 한 항에 있어서,The method according to any one of claims 1 to 7,
    리튬 디플루오로 비스옥살레이토 포스페이트를 더 포함하는 것인 전해액 첨가제.An electrolyte solution additive further comprising lithium difluoro bisoxalato phosphate.
  9. 청구항 8에 있어서,The method according to claim 8,
    상기 전해액 첨가제는 질소 원자 함유 화합물 유래 음이온과 Cs+ 또는 Rb+와의 염 및 리튬 디플루오로 비스옥살레이토 포스페이트를 중량비로 1 : 1 내지 1 : 4로 포함하는 것인 전해액 첨가제.The electrolyte additive is an electrolyte solution additive comprising a 1: 1 to 1: 4 by weight ratio of a nitrogen atom-containing compound-derived anion and Cs + or Rb + and lithium difluoro bisoxalato phosphate.
  10. 리튬염;Lithium salts;
    비수성 유기용매; 및Non-aqueous organic solvents; And
    청구항 8의 전해액 첨가제를 포함하는 것인 비수성 전해액.A non-aqueous electrolyte solution comprising the electrolyte solution additive of claim 8.
  11. 청구항 10에 있어서,The method according to claim 10,
    상기 전해액 첨가제의 함량은 상기 비수성 전해액 총량을 기준으로 0.05~10 중량%인 것인 비수성 전해액.The amount of the electrolyte additive is a non-aqueous electrolyte of 0.05 to 10% by weight based on the total amount of the non-aqueous electrolyte.
  12. 청구항 10에 있어서,The method according to claim 10,
    상기 리튬염은 LiPF6, LiFSI, LiAsF6, LiCF3SO3, LiN(CF3SO2)2, LiBF4, LiSbF6, LiN(C2F5SO2)2, LiAlO4, LiAlCl4, LiSO3CF3, LiTFSI, LiDFOB 및 LiClO4로 이루어진 군에서 선택되는 1종 이상을 포함하는 것인 비수성 전해액.The lithium salt is LiPF 6 , LiFSI, LiAsF 6 , LiCF 3 SO 3 , LiN (CF 3 SO 2 ) 2 , LiBF 4 , LiSbF 6 , LiN (C 2 F 5 SO 2 ) 2 , LiAlO 4 , LiAlCl 4 , LiSO 3 CF 3 , LiTFSI, LiDFOB and a non-aqueous electrolyte solution containing at least one selected from the group consisting of LiClO 4 .
  13. 청구항 10에 있어서, The method according to claim 10,
    상기 리튬염은 LiPF6 를 포함하는 것인 비수성 전해액.The lithium salt is a non-aqueous electrolyte solution containing LiPF 6 .
  14. 청구항 10에 있어서,The method according to claim 10,
    상기 비수성 유기 용매는 에테르, 에스테르, 아미드, 선형 카보네이트, 환형 카보네이트, 인산계 화합물, 니트릴계 화합물, 불소화 에테르계 화합물, 및 불소화 방향족계 화합물로 이루어진 군에서 선택되는 1종 이상을 포함하는 것인 비수성 전해액.The non-aqueous organic solvent includes one or more selected from the group consisting of ethers, esters, amides, linear carbonates, cyclic carbonates, phosphoric acid compounds, nitrile compounds, fluorinated ether compounds, and fluorinated aromatic compounds. Non-aqueous electrolyte.
  15. 양극 활물질을 포함하는 양극;A positive electrode including a positive electrode active material;
    음극 활물질을 포함하는 음극; A negative electrode including a negative electrode active material;
    상기 양극과 상기 음극 사이에 개재된 분리막; 및 A separator interposed between the anode and the cathode; And
    청구항 10의 비수성 전해액을 포함하는 것인 리튬 이차전지.Lithium secondary battery comprising a non-aqueous electrolyte of claim 10.
  16. 청구항 15에 있어서, The method according to claim 15,
    상기 양극 활물질은 하기 화학식 7 내지 화학식 9의 화합물로 이루어진 군에서 1종 이상을 포함하는 것인 리튬 이차 전지:The positive electrode active material is a lithium secondary battery comprising at least one type in the group consisting of the compounds of Formulas 7 to 9:
    [화학식 7][Formula 7]
    Li[NiaCobMnc]O2 (0.1 ≤ c ≤ 0.5,　0　<　a+b　< 0.9, a+b+c=1);Li [Ni a Co b Mn c ] O 2 (0.1 ≦ c ≦ 0.5, 0 <a + b <0.9, a + b + c = 1);
    [화학식 8][Formula 8]
    LiMn2 - xMxO4 (M=Ni, Co, Fe, P, S, Zr, Ti 및 Al로 이루어진 군에서 선택되는 하나 이상의 원소, 0 < x ≤ 2) ;LiMn 2 - x M x O 4 (M = Ni, Co, Fe, P, S, Zr, Ti and Al, at least one element selected from the group consisting of 0 <x ≤ 2);
    [화학식 9][Formula 9]
    Li1 + aCoxM1 - xBX4 (M=Al, Mg, Ni, Co, Mn, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn 및 Y 로 이루어진 군에서 선택되는 하나 이상의 원소이고, X는 O, F, 및 N으로 이루어진 군에서 선택되는 하나 이상의 원소이며, B는 P, S 또는 이들의 혼합 원소이고, 0≤a≤0.2, 0.5≤x≤1이다).Li 1 + a Co x M 1 - x BX 4 (M = Al, Mg, Ni, Co, Mn, Ti, Ga, Cu, V, Nb, Zr, Ce, In, Zn and Y) At least one element, X is at least one element selected from the group consisting of O, F, and N, B is P, S or a mixture thereof, and 0 ≦ a ≦ 0.2, 0.5 ≦ x ≦ 1).
  17. 청구항 15에 있어서, The method according to claim 15,
    상기 양극 활물질은 Li[Ni0.6Co0.2Mn0.2]O2, Li(Ni0.5Co0.2Mn0.3)O2 , Li[Ni1/3Co1/3Mn1/3]O2, 및 LiCoO2로 이루어진 군에서 선택되는 1종 이상을 포함하는 것인 리튬 이차전지.The positive electrode active material is Li [Ni 0.6 Co 0.2 Mn 0.2 ] O 2 , Li (Ni 0.5 Co 0.2 Mn 0.3 ) O 2 , Li [Ni 1/3 Co 1/3 Mn 1/3 ] O 2 , and LiCoO 2 . Lithium secondary battery comprising one or more selected from the group consisting of.
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