WO2016053041A1 - Gel polymer electrolyte and lithium secondary battery containing same - Google Patents

Gel polymer electrolyte and lithium secondary battery containing same Download PDF

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Publication number
WO2016053041A1
WO2016053041A1 PCT/KR2015/010416 KR2015010416W WO2016053041A1 WO 2016053041 A1 WO2016053041 A1 WO 2016053041A1 KR 2015010416 W KR2015010416 W KR 2015010416W WO 2016053041 A1 WO2016053041 A1 WO 2016053041A1
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Prior art keywords
compound
polymer electrolyte
gel polymer
carbonate
composition
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PCT/KR2015/010416
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French (fr)
Korean (ko)
Inventor
박솔지
안경호
오정우
이철행
정이진
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주식회사 엘지화학
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Application filed by 주식회사 엘지화학 filed Critical 주식회사 엘지화학
Priority to US15/516,146 priority Critical patent/US10276893B2/en
Priority to JP2017517750A priority patent/JP6612859B2/en
Priority to EP15848091.3A priority patent/EP3203566B1/en
Priority to CN201580053802.1A priority patent/CN106797053B/en
Priority claimed from KR1020150138643A external-priority patent/KR101797295B1/en
Publication of WO2016053041A1 publication Critical patent/WO2016053041A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • 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 a gel polymer electrolyte and a secondary battery comprising the same.
  • lithium secondary batteries having high energy density and voltage among these secondary batteries are commercially used and widely used.
  • Lithium metal oxide is used as a positive electrode active material of a lithium secondary battery, and lithium metal, a lithium alloy, crystalline or amorphous carbon or a carbon composite material is used as a negative electrode active material.
  • the active material is applied to a current collector with a suitable thickness and length, or the active material itself is applied in a film shape to form an electrode group by winding or laminating together with a separator, which is an insulator, and then put it in a can or a similar container, and then injecting an electrolyte solution.
  • a secondary battery is manufactured.
  • an electrolyte in a liquid state particularly an ion conductive organic liquid electrolyte in which salts are dissolved in a non-aqueous organic solvent, has been mainly used.
  • the use of the electrolyte in the liquid state is not only highly likely to deteriorate the electrode material and volatilize the organic solvent, but also has problems in safety such as combustion due to an increase in the ambient temperature and the temperature of the battery itself.
  • a lithium secondary battery has a problem in that gas is generated inside the battery due to decomposition of a carbonate organic solvent and / or side reaction between the organic solvent and the electrode during charging and discharging, thereby expanding the battery thickness, and the reaction is accelerated at high temperature storage. Thus, the amount of gas generated is further increased.
  • This continuously generated gas causes an increase in the internal pressure of the battery, which causes the center of the specific surface of the battery to deform such as swelling of the square battery in a specific direction, as well as a local difference in adhesion at the electrode surface of the battery. This causes the problem that the electrode reaction does not occur equally in the entire electrode surface. Therefore, the performance and safety degradation of the battery is necessarily caused.
  • the problem to be solved by the present invention is to provide a composition for a gel polymer electrolyte and a lithium secondary battery comprising the same by including a mixed compound in the electrolyte, which can not only improve the life of the battery but also improve the capacity characteristics of the battery. will be.
  • the present invention provides a composition for a gel polymer electrolyte comprising an electrolyte solution solvent, a lithium salt, a polymerization initiator, and a mixed compound of the first compound and the second compound.
  • the first compound may be an amine compound including polyethylene glycol as a functional group
  • the second compound may be an epoxy compound
  • the present invention also provides a lithium secondary battery including a positive electrode, a negative electrode, a separator, and a gel polymer electrolyte, wherein the gel polymer electrolyte is formed by polymerizing the composition for the gel polymer electrolyte.
  • the gel polymer electrolyte may include an oligomer represented by Chemical Formulas 1 and 2 below.
  • n and m are each an integer of 1 to 20, and each of R 1 to R 5 is independently hydrogen or —CO (CH 2 ) 3 COO— (CH 2 CH 2 O) x—CH 3 , x is an integer from 1 to 100, wherein R 1 to R at least 3 or more of the 5, -CO (CH 2) 3 COO- ( CH 2 CH 2 O) x -CH 3.
  • a is an integer from 1 to 100.
  • a lithium secondary compound is obtained by including an amine compound in which a first compound contains polyethylene glycol as a functional group, and a second compound include a mixed compound of a first compound and a second compound, which are epoxy compounds.
  • Figure 2 is a graph showing the increase in thickness after high temperature storage of the secondary battery prepared in Examples 5-7.
  • Gel polymer electrolyte composition according to an embodiment of the present invention comprises an electrolyte solvent, a lithium salt, a polymerization initiator, and a mixed compound of the first compound and the second compound, wherein the first compound comprises polyethylene glycol as a functional group It may be an amine compound, the second compound may be an epoxy compound.
  • the first compound may be polyimine including ethylene glycol, and for example, poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) may be applied.
  • the second compound may be polyethylene glycol having two or more epoxy groups, and for example, polyethylene diglycidyl ether or the like may be applied.
  • the solubility in the composition for gel polymer electrolyte is increased and is stably fixed on the gel structure in the gel polymer electrolyte.
  • the presence of the second compound including the epoxy-based compound may be mixed to more easily perform the hopping phenomenon of FIG. 1 to be described later to increase the ion mobility of the gel polymer electrolyte generated by the polymerization reaction, thereby improving output characteristics. Can improve.
  • the first compound may be included in an amount of 1 to 15% by weight, specifically 3 to 12% by weight, and more specifically 4 to 10% by weight, based on the total weight of the gel polymer electrolyte composition.
  • the first compound When the first compound is included in an amount of 1% by weight or more based on the total weight of the gel polymer electrolyte composition, gelling of the gel polymer electrolyte composition may be more smoothly performed, and the high temperature storage property is improved, thereby increasing the thickness of the battery during high temperature storage. It can be reduced, the tendency is more pronounced when the content is specifically 3% by weight, more specifically 4% by weight.
  • the first compound when the first compound is included in an amount of 15% by weight or less based on the total weight of the composition for the gel polymer electrolyte, while exhibiting the effect of improving the gelling and high temperature storage characteristics as described above, preventing the increase in resistance of the battery due to excessive content can do.
  • the first compound and the second compound may be in a weight ratio of 1: 0.2 to 0.6, specifically 1: 0.25 to 0.5.
  • the first compound and the second compound satisfies the weight ratio of 1: 0.2 to 0.6, gelation of the gel polymer electrolyte composition can be made more smoothly, and the high temperature storage property is improved to reduce the increase in thickness of the battery during high temperature storage.
  • the hopping phenomenon may be more easily performed to increase the ion mobility of the gel polymer electrolyte produced by the polymerization reaction, thereby improving output characteristics.
  • the mixed compound when the mixed compound is included in the gel polymer electrolyte composition, unlike the case of using a general electrolyte solution in which the metal ions eluted from the positive electrode are precipitated from the negative electrode, eluted from the positive electrode Metal ions can be combined with the mixed compound to reduce the precipitation of metal at the negative electrode. As a result, the charge and discharge efficiency of the lithium secondary battery can be improved and good cycle characteristics can be exhibited.
  • the composition for a gel polymer electrolyte including the monomer having the functional group is applied to a lithium secondary battery, there is little risk of leakage and a flame retardant property to improve the stability of the battery.
  • the mixed compound of the first compound and the second compound may be 0.1 wt% to 10 wt%, preferably 0.5 wt% to 5 wt%, based on the total weight of the composition for gel polymer electrolyte. If it is less than 0.1% by weight it is difficult to gel the gel polymer electrolyte properties, and if it exceeds 10% by weight may increase the resistance due to the excessive content of the monomer may decrease the battery performance.
  • the first compound and the second compound may be mixed to react for 2 minutes to 12 hours in a temperature range of 30 °C to 100 °C to prepare a polymerizable monomer.
  • the content ratio of the monomer having a functional group and the branched monomer may be, for example, a weight ratio of 1:18 to 1:75, but is not limited thereto.
  • lithium ions are small in size, and thus, are not only relatively easy to move directly, but also easily move to a hopping phenomenon in the electrolyte as shown in FIG. 1.
  • the ionizable lithium salts included in the electrolyte composition according to an embodiment of the present invention may be, for example, LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiClO 4 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) 2 , CF 3 SO 3 Li, LiC (CF 3 SO 2 ) 3 And LiC 4 BO 8 It may be any one selected from the group consisting of or a mixture of two or more thereof. It is not.
  • electrolyte solvent used according to an embodiment of the present invention those conventionally used in the electrolyte for lithium secondary batteries may be used without limitation, and for example, ether, ester, amide, linear carbonate, or cyclic carbonate may be used alone. Or two or more kinds thereof can be mixed.
  • carbonate compounds which are typically cyclic carbonates, linear carbonates or mixtures thereof may be included.
  • cyclic carbonate compound examples include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene Carbonate, vinylene carbonate, and any one selected from the group consisting of halides thereof, or a mixture of two or more thereof.
  • linear carbonate compound examples include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC) and ethylpropyl carbonate (EPC). Any one selected from the group consisting of, or a mixture of two or more thereof may be representatively used, but is not limited thereto.
  • propylene carbonate and ethylene carbonate which are cyclic carbonates in the carbonate electrolyte solvent, may be preferably used because they have high dielectric constants and dissociate lithium salts in the electrolyte well, such as ethylmethyl carbonate and diethyl carbonate.
  • a low viscosity, low dielectric constant linear carbonate such as dimethyl carbonate is mixed and used in an appropriate ratio, an electrolyte having high electrical conductivity can be made, and thus it can be used more preferably.
  • ester in the electrolyte solvent is methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, ⁇ -butyrolactone, ⁇ -valerolactone, ⁇ -caprolactone, ⁇ -valerolactone And ⁇ -caprolactone, but any one selected from the group consisting of, or a mixture of two or more thereof may be used, but is not limited thereto.
  • a polymerization initiator may be used a conventional polymerization initiator known in the art.
  • Non-limiting examples of the polymerization initiator are benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-tert-butyl peroxide, organic peroxides and hydros such as t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide, and hydrogen peroxide Peroxides with 2,2'-azobis (2-cyanobutane), 2,2'-azobis (methylbutyronitrile), AIBN (2,2'-Azobis (iso-butyronitrile)) and AMVN (2 And azo compounds such as 2'-Azobisdimethyl-Valeronitrile), but are not limited thereto.
  • the polymerization initiator is decomposed by heat in the cell, by way of non-limiting example, 30 ° C. to 100 ° C. or at room temperature (5 ° C. to 30 ° C.) to form radicals, and react with the polymerizable monomer by free radical polymerization. To form a gel polymer electrolyte.
  • the polymerization initiator may be used in an amount of 0.01% by weight to 2% by weight based on the total weight of the composition for gel polymer electrolyte. If the polymerization initiator is more than 2% by weight, gelation may occur too quickly or the unreacted initiator remains after the gel polymer electrolyte composition is injected into the battery, which adversely affects the battery performance. Conversely, the polymerization initiator is less than 0.01% by weight. There is a problem that the gelation is not well done.
  • the gel polymer electrolyte composition according to an embodiment of the present invention may optionally contain other additives known in the art, in addition to the components described above.
  • Gel polymer electrolyte according to an embodiment of the present invention may be formed by polymerizing the composition for gel polymer electrolyte according to a conventional method known in the art.
  • the gel polymer electrolyte may be formed by in-situ polymerization of the composition for gel polymer electrolyte in the secondary battery.
  • Injecting the composition for the gel polymer electrolyte according to the polymerization may include the step of forming a gel polymer electrolyte.
  • the in-situ polymerization reaction in the lithium secondary battery may proceed through thermal polymerization.
  • the polymerization time takes about 2 minutes to 12 hours
  • the thermal polymerization temperature may be 30 to 100 °C.
  • a gel polymer electrolyte is formed.
  • oligomers in which the polymerizable monomers are crosslinked with each other by a polymerization reaction are formed, and the liquid electrolyte in which the electrolyte salt is dissociated in the electrolyte solvent can be uniformly impregnated in the formed oligomer.
  • the oligomer according to an embodiment of the present invention may be a mixed form of the oligomer represented by the formula (1) and (2).
  • n and m are each an integer of 1 to 20, and each of R 1 to R 5 is independently hydrogen or —CO (CH 2 ) 3 COO— (CH 2 CH 2 O) x—CH 3 , x is an integer from 1 to 100, wherein R 1 to R at least 3 or more of the 5, -CO (CH 2) 3 COO- ( CH 2 CH 2 O) x -CH 3.
  • a is an integer from 1 to 100.
  • the lithium secondary battery according to an embodiment of the present invention has a charge voltage of 3.0V to 5.0V, and excellent capacity characteristics of the lithium secondary battery in both a normal voltage and a high voltage region.
  • the electrode of the lithium secondary battery may be manufactured by a conventional method known in the art.
  • a slurry may be prepared by mixing and stirring a solvent, a binder, a conductive material, and a dispersant in an electrode active material, and then applying the coating (coating) to a current collector of a metal material, compressing, and drying the electrode to prepare an electrode.
  • the positive electrode active material in the positive electrode may be applied to a general voltage or a high voltage, and may be used without limitation as long as it is a compound capable of reversibly intercalating / deintercalating lithium.
  • such oxides may include sulfides, selenides, and halides.
  • a carbon material lithium metal, silicon or tin, etc. which can normally occlude and release lithium ions may be used.
  • a carbon material may be used, and as the carbon material, both low crystalline carbon and high crystalline carbon may be used.
  • Soft crystalline carbon and hard carbon are typical low crystalline carbon, and high crystalline carbon is natural graphite, Kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber.
  • High temperature calcined carbon such as (mesophase pitch based carbon fiber), meso-carbon microbeads, Mesophase pitches and petroleum or coal tar pitch derived cokes.
  • the positive electrode and / or negative electrode may be prepared by mixing and stirring a binder, a solvent, a conductive material and a dispersant, which may be commonly used as necessary, to prepare a slurry, and then applying the same to a current collector and compressing the negative electrode.
  • 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
  • porous polymer films conventionally used as separators for example, polyolefins such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer, etc.
  • the porous polymer film made of the polymer may be used alone or by laminating them, or a conventional porous nonwoven fabric, for example, a non-woven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, or the like may be used. It is not.
  • the external shape of the lithium secondary battery according to the exemplary embodiment of the present invention is not particularly limited, but may be cylindrical, square, pouch type, or coin type using a can.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • t-butyl peroxy-2-ethylhexanoate 0.25 weight% of t-butyl peroxy-2-ethylhexanoate is added as a polymerization initiator with respect to the total weight of the composition for electrolytes which summed the weight of the said electrolyte solution, and poly (ethylene imine) -graft-poly (ethylene Glycol) (PEI-PEG) 2% by weight was added, followed by polyethylene glycol diglycidyl ether as the second compound in an amount of 1/3% by weight relative to the first compound. This produced a composition for gel polymer electrolyte.
  • PEI-PEG poly (ethylene imine) -graft-poly (ethylene Glycol)
  • Example 1 the poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) as the first compound in an amount of 5% by weight, and polyethylene glycol diglycidyl ether as the second compound
  • a gel polymer electrolyte composition was prepared in the same manner as in Example 1, except that the compound was used in an amount of 1/3 wt% based on 1 compound.
  • Example 1 except that poly (ethylene imine) (PEI) was used in place of poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) as the first compound. In the same manner as in the gel polymer electrolyte composition was prepared.
  • PEI poly (ethylene imine)
  • PEI-PEG poly (ethylene glycol)
  • Example 2 except that poly (ethylene imine) (PEI) was used instead of poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) as the first compound.
  • PEI poly (ethylene imine)
  • PEG poly (ethylene imine) -graft-poly (ethylene glycol)
  • LiCoO 2 as a positive electrode active material
  • carbon black as a conductive material
  • PVdF as a binder
  • NMP 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.
  • Al aluminum
  • 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 material 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 battery was assembled using a separator consisting of the positive electrode, the negative electrode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP), and the gel polymer electrolyte composition prepared in Example 1 was injected into the assembled battery. Then, the secondary battery was manufactured by heating at 80 ° C. for 2 to 30 minutes.
  • a separator consisting of the positive electrode, the negative electrode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP), and the gel polymer electrolyte composition prepared in Example 1 was injected into the assembled battery. Then, the secondary battery was manufactured by heating at 80 ° C. for 2 to 30 minutes.
  • Example 5 except for using the gel polymer electrolyte composition prepared in Examples 2 to 4 instead of the gel polymer electrolyte composition prepared in Example 1, the same as in Example 5 Each secondary battery was manufactured by the method of.
  • the gel polymer electrolyte composition prepared in Examples 1 to 4 was cured at 65 ° C. to observe whether gelation occurred, and the results are shown in Table 1 below.
  • a mixed compound using poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) as the first compound and polyethylene glycol diglycidyl ether as the second compound The composition for a gel polymer electrolyte comprising a 2% by weight of the first compound, the content of the second compound is 1/3% by weight compared to the first compound (Example 1) and the first compound 5% by weight and the content of the second compound was 1/3 of the weight of the first compound was all gelled smoothly.
  • Each secondary battery prepared in Examples 5 to 7 was charged at a C-rate of 0.1 C (unit: mA / g) until the voltage became 4.4 V, and then the current was Charged further until 0.05 C. Then rest for 10 minutes. Then, each battery was discharged at a rate of 0.3 C until the voltage became 2.8 V. Each discharge capacity was measured, and the results are shown in Table 2, and the experiment of the battery of Example 8 without gelation of the electrolyte was not conducted.
  • the secondary battery using the composition for gel polymer electrolyte containing the mixed compound of the first compound and the second compound exhibited excellent capacity characteristics, in particular, containing a polyethylene glycol functional group as the first compound.
  • poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) which is an amine compound
  • poly (ethylene imine) which is an amine compound containing no polyethylene glycol functional group
  • the content of the first compound and the second compound were the same as compared with the case of (PEI) (Example 7), it was found to exhibit better capacity characteristics.
  • PEI poly (ethylene imine)

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Abstract

The present invention relates to a composition for a gel polymer electrolyte containing an electrolyte solvent, lithium salt, a polymerisation initiator and a mixed compound of a first compound and a second compound; and a lithium secondary battery comprising a positive electrode, a negative electrode, a separation membrane and a gel polymer electrolyte. A lithium secondary battery is provided, wherein the gel polymer electrolyte is formed by polymerising the gel polymer electrolyte composition. The gel polymer electrolyte composition of the present invention includes a mixed compound of a first compound and a second compound, wherein the first compound is an amine-based compound including polyethylene glycol as a functional group and the second compound is an epoxy-based compound; and can thereby easily induce a hopping phenomenon when applied to a lithium secondary battery, improve battery life, exhibit excellent storage at high temperatures and improve battery capacity.

Description

겔 폴리머 전해질 및 이를 포함하는 리튬 이차전지Gel polymer electrolyte and lithium secondary battery comprising same
[관련출원과의 상호 인용][Cross-cited with Related Applications]
본 출원은 2014년 10월 02일자 한국 특허 출원 제10-2014-0133469호 및 2015년 10월 01일자 한국 특허 출원 제10-2015-0138643호에 기초한 우선권의 이익을 주장하며, 해당 한국 특허 출원의 문헌에 개시된　모든 내용은 본 명세서의 일부로서 포함된다.This application claims the benefit of priority based on Korean Patent Application No. 10-2014-0133469 dated October 02, 2014 and Korean Patent Application No. 10-2015-0138643 dated October 01, 2015. All content disclosed in the literature is included as part of this specification.
[기술분야][Technical Field]
본 발명은 겔 폴리머 전해질 및 이를 포함하는 이차전지에 관한 것이다.The present invention relates to a gel polymer electrolyte and a secondary battery comprising the same.
모바일 기기에 대한 기술 개발과 수요가 증가함에 따라 에너지원으로서의 이차 전지의 수요가 급격히 증가하고 있고, 이러한 이차 전지 중 높은 에너지 밀도와 전압을 가지는 리튬 이차 전지가 상용화되어 널리 사용되고 있다.As technology development and demand for mobile devices increase, the demand for secondary batteries as energy sources is rapidly increasing, and lithium secondary batteries having high energy density and voltage among these secondary batteries are commercially used and widely used.
리튬 이차 전지의 양극 활물질로는 리튬 금속 산화물이 사용되고, 음극 활물질로는 리튬 금속, 리튬 합금, 결정질 또는 비정질 탄소 또는 탄소 복합체가 사용되고 있다. 상기 활물질을 적당한 두께와 길이로 집전체에 도포하거나 또는 활물질 자체를 필름 형상으로 도포하여 절연체인 분리막과 함께 감거나 적층하여 전극군을 만든 다음, 캔 또는 이와 유사한 용기에 넣은 후, 전해액을 주입하여 이차 전지를 제조한다.Lithium metal oxide is used as a positive electrode active material of a lithium secondary battery, and lithium metal, a lithium alloy, crystalline or amorphous carbon or a carbon composite material is used as a negative electrode active material. The active material is applied to a current collector with a suitable thickness and length, or the active material itself is applied in a film shape to form an electrode group by winding or laminating together with a separator, which is an insulator, and then put it in a can or a similar container, and then injecting an electrolyte solution. A secondary battery is manufactured.
종래 전기 화학 반응을 이용한 전지, 전기 이중층 캐패시터 등의 전기 화학 소자용 전해질로는 액체 상태의 전해질, 특히 비수계 유기 용매에 염을 용해한 이온 전도성 유기 액체 전해질이 주로 사용되어 왔다. Conventionally, as electrolytes for electrochemical devices such as batteries and electric double layer capacitors using an electrochemical reaction, an electrolyte in a liquid state, particularly an ion conductive organic liquid electrolyte in which salts are dissolved in a non-aqueous organic solvent, has been mainly used.
그러나 이와 같이 액체 상태의 전해질을 사용하면, 전극 물질이 퇴화되고 유기 용매가 휘발될 가능성이 클 뿐만 아니라, 주변 온도 및 전지 자체의 온도 상승에 의한 연소 등과 같은 안전성에 문제가 있다. 특히, 리튬 이차 전지는 충방전 진행시 카보네이트 유기 용매의 분해 및/또는 유기 용매와 전극과의 부반응에 의해 전지 내부에 가스가 발생하여 전지 두께를 팽창시키는 문제점이 있으며, 고온 저장시에는 이러한 반응이 가속화되어 가스 발생량이 더 증가하게 된다. However, the use of the electrolyte in the liquid state is not only highly likely to deteriorate the electrode material and volatilize the organic solvent, but also has problems in safety such as combustion due to an increase in the ambient temperature and the temperature of the battery itself. In particular, a lithium secondary battery has a problem in that gas is generated inside the battery due to decomposition of a carbonate organic solvent and / or side reaction between the organic solvent and the electrode during charging and discharging, thereby expanding the battery thickness, and the reaction is accelerated at high temperature storage. Thus, the amount of gas generated is further increased.
이와 같이 지속적으로 발생된 가스는 전지의 내압 증가를 유발시켜 각형 전지가 특정 방향으로 부풀어오르는 등 전지의 특정면의 중심부가 변형되는 현상을 초래할 뿐만 아니라, 전지 내 전극면에서의 밀착성에서 국부적인 차이점을 발생시켜 전극 반응이 전체 전극면에서 동일하게 일어나지 못하는 문제를 야기한다. 따라서 전지의 성능과 안전성 저하가 필수적으로 초래되게 된다.This continuously generated gas causes an increase in the internal pressure of the battery, which causes the center of the specific surface of the battery to deform such as swelling of the square battery in a specific direction, as well as a local difference in adhesion at the electrode surface of the battery. This causes the problem that the electrode reaction does not occur equally in the entire electrode surface. Therefore, the performance and safety degradation of the battery is necessarily caused.
일반적으로, 전지의 안전성은 액체 전해질 < 겔 폴리머 전해질 < 고체 고분자 전해질 순서로 향상되나, 이에 반해 전지 성능은 감소하는 것으로 알려져 있다. 이러한 열등한 전지 성능으로 인하여 아직까지 고체 고분자 전해질을 채택한 전지들은 상업화되지 않은 것으로 알려져 있다.In general, battery safety is known to be improved in the order of liquid electrolyte <gel polymer electrolyte <solid polymer electrolyte, whereas battery performance is known to decrease. Due to such inferior battery performance, it is known that batteries employing a solid polymer electrolyte have not been commercialized yet.
본 발명의 해결하고자 하는 과제는 혼합 화합물을 전해액에 포함함으로써, 전지의 수명을 향상시킬 수 있을 뿐만 아니라 전지의 용량 특성을 향상시킬 수 있는 겔 폴리머 전해질용 조성물 및 이를 포함하는 리튬 이차 전지를 제공하는 것이다.The problem to be solved by the present invention is to provide a composition for a gel polymer electrolyte and a lithium secondary battery comprising the same by including a mixed compound in the electrolyte, which can not only improve the life of the battery but also improve the capacity characteristics of the battery. will be.
상기와 같은 목적을 달성하기 위하여, 본 발명은 전해액 용매, 리튬염, 중합 개시제, 및 제1 화합물과 제2 화합물의 혼합 화합물을 포함하는 겔 폴리머 전해질용 조성물을 제공한다. In order to achieve the above object, the present invention provides a composition for a gel polymer electrolyte comprising an electrolyte solution solvent, a lithium salt, a polymerization initiator, and a mixed compound of the first compound and the second compound.
상기 제1 화합물은 작용기로서 폴리에틸렌 글리콜을 포함하는 아민계 화합물일 수 있고, 상기 제2 화합물은 에폭시계 화합물일 수 있다.The first compound may be an amine compound including polyethylene glycol as a functional group, and the second compound may be an epoxy compound.
또한, 본 발명은 양극, 음극, 분리막, 및 겔 폴리머 전해질을 포함하는 리튬 이차 전지로서, 상기 겔 폴리머 전해질은 상기 겔 폴리머 전해질용 조성물을 중합시켜 형성된 리튬 이차 전지를 제공한다. The present invention also provides a lithium secondary battery including a positive electrode, a negative electrode, a separator, and a gel polymer electrolyte, wherein the gel polymer electrolyte is formed by polymerizing the composition for the gel polymer electrolyte.
상기 겔 폴리머 전해질은 이하 화학식 1 및 2로 표시되는 올리고머를 포함하는 것일 수 있다.The gel polymer electrolyte may include an oligomer represented by Chemical Formulas 1 and 2 below.
[화학식 1][Formula 1]
Figure PCTKR2015010416-appb-I000001
Figure PCTKR2015010416-appb-I000001
여기서 상기 n, m은 각각 1 내지 20의 정수이고, 상기 R1 내지 R5는 각각 독립적으로 수소, 또는 -CO(CH2)3COO-(CH2CH2O)x-CH3인 것이고, x는 1 내지 100의 정수이며, 상기 R1 내지 R5 중 적어도 (3) 이상은 -CO(CH2)3COO-(CH2CH2O)X-CH3이다.Wherein n and m are each an integer of 1 to 20, and each of R 1 to R 5 is independently hydrogen or —CO (CH 2 ) 3 COO— (CH 2 CH 2 O) x—CH 3 , x is an integer from 1 to 100, wherein R 1 to R at least 3 or more of the 5, -CO (CH 2) 3 COO- ( CH 2 CH 2 O) x -CH 3.
[화학식 2][Formula 2]
Figure PCTKR2015010416-appb-I000002
Figure PCTKR2015010416-appb-I000002
여기서 상기 a는 1 내지 100의 정수이다.Wherein a is an integer from 1 to 100.
본 발명의 겔 폴리머 전해질용 조성물은, 제1 화합물은 작용기로서 폴리에틸렌 글리콜을 포함하는 아민계 화합물, 및 제2 화합물은 에폭시계 화합물인 제1 화합물과 제2 화합물의 혼합 화합물을 포함함으로써, 리튬 이차 전지에 적용할 경우, 호핑 현상을 용이하게 유도함으로써, 전지의 수명을 향상시킬 수 있을 뿐만 아니라, 우수한 고온 저장성을 발휘하며, 전지의 용량 특성을 향상시킬 수 있다.In the gel polymer electrolyte composition of the present invention, a lithium secondary compound is obtained by including an amine compound in which a first compound contains polyethylene glycol as a functional group, and a second compound include a mixed compound of a first compound and a second compound, which are epoxy compounds. When applied to a battery, by easily inducing a hopping phenomenon, it is possible not only to improve the life of the battery, but also to exhibit excellent high-temperature storage properties and to improve the capacity characteristics of the battery.
도 1은 겔 폴리머 전해질용 조성물을 사용한 경우의 리튬 이온의 이동 원리를 나타낸 도면이다.BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows the principle of the movement of lithium ion in the case of using the composition for gel polymer electrolytes.
도 2는 실시예 5 내지 7에서 제조된 이차 전지의 고온 보관 후의 두께 증가정도를 나타낸 그래프이다. Figure 2 is a graph showing the increase in thickness after high temperature storage of the secondary battery prepared in Examples 5-7.
이하, 본 발명에 대한 이해를 돕기 위해 본 발명을 더욱 상세하게 설명한다.Hereinafter, the present invention will be described in more detail to aid in understanding the present invention.
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.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 실시예에 따른 겔 폴리머 전해질용 조성물은 전해액 용매, 리튬염, 중합 개시제, 및 제1 화합물과 제2 화합물의 혼합 화합물을 포함하고, 상기 제1 화합물은 작용기로서 폴리에틸렌 글리콜을 포함하는 아민계 화합물일 수 있고, 상기 제2 화합물은 에폭시계 화합물일 수 있다.Gel polymer electrolyte composition according to an embodiment of the present invention comprises an electrolyte solvent, a lithium salt, a polymerization initiator, and a mixed compound of the first compound and the second compound, wherein the first compound comprises polyethylene glycol as a functional group It may be an amine compound, the second compound may be an epoxy compound.
상기 제1 화합물은 구체적으로 에틸렌 글리콜이 포함된 폴리이민일 수 있고, 예를 들어, 폴리(에틸렌 이민)-그라프트-폴리(에틸렌 글리콜) (PEI-PEG) 등이 적용될 수 있다. 또한, 상기 제2 화합물은 두 개 이상의 에폭시 그룹을 가진 폴리에틸렌 글리콜일 수 있으며, 예를 들어, 폴리에틸렌 다이글리시딜 에테르 등이 적용될 수 있다.Specifically, the first compound may be polyimine including ethylene glycol, and for example, poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) may be applied. In addition, the second compound may be polyethylene glycol having two or more epoxy groups, and for example, polyethylene diglycidyl ether or the like may be applied.
본 발명의 일 실시예에 따르면, 상기 제1 화합물에 포함된 폴리에틸렌 글리콜 작용기가 화합물에 포함되어 있음으로써, 겔 폴리머 전해질용 조성물에 대한 용해도가 증가하며, 겔 폴리머 전해질 내의 겔 구조상에 안정적으로 고정되어 존재할 수 있도록 하고, 에폭시계 화합물을 포함하는 제2 화합물이 혼합됨으로써 후술하는 도 1의 호핑 현상을 보다 용이하게 수행할 수 있도록 하여 중합반응으로 생성되는 겔 폴리머 전해질의 이온 이동도를 높여 출력 특성을 향상 시킬 수 있다.According to an embodiment of the present invention, since the polyethylene glycol functional group included in the first compound is included in the compound, the solubility in the composition for gel polymer electrolyte is increased and is stably fixed on the gel structure in the gel polymer electrolyte. The presence of the second compound including the epoxy-based compound may be mixed to more easily perform the hopping phenomenon of FIG. 1 to be described later to increase the ion mobility of the gel polymer electrolyte generated by the polymerization reaction, thereby improving output characteristics. Can improve.
상기 제1 화합물은 상기 겔 폴리머 전해질용 조성물 총 중량에 대해 1 내지 15 중량%, 구체적으로 3 내지 12 중량%, 더욱 구체적으로 4 내지 10 중량%의 양으로 포함될 수 있다. The first compound may be included in an amount of 1 to 15% by weight, specifically 3 to 12% by weight, and more specifically 4 to 10% by weight, based on the total weight of the gel polymer electrolyte composition.
상기 제1 화합물이 상기 겔 폴리머 전해질용 조성물 총 중량에 대해 1 중량% 이상 포함될 경우, 겔 폴리머 전해질용 조성물의 겔화가 보다 원활하게 이루어질 수 있고, 고온 저장 특성이 향상되어 고온 저장시 전지의 두께 증가를 감소시킬 수 있으며, 그 함량이 구체적으로 3 중량%, 더욱 구체적으로 4 중량%일 경우 그 경향이 더욱 두드러진다. 또한, 상기 제1 화합물이 상기 겔 폴리머 전해질용 조성물 총 중량에 대해 15 중량% 이하로 포함될 경우, 상기한 바와 같은 겔화 및 고온 저장 특성 향상 효과를 발휘하면서도, 과량 함유에 따른 전지의 저항 증가를 방지할 수 있다. When the first compound is included in an amount of 1% by weight or more based on the total weight of the gel polymer electrolyte composition, gelling of the gel polymer electrolyte composition may be more smoothly performed, and the high temperature storage property is improved, thereby increasing the thickness of the battery during high temperature storage. It can be reduced, the tendency is more pronounced when the content is specifically 3% by weight, more specifically 4% by weight. In addition, when the first compound is included in an amount of 15% by weight or less based on the total weight of the composition for the gel polymer electrolyte, while exhibiting the effect of improving the gelling and high temperature storage characteristics as described above, preventing the increase in resistance of the battery due to excessive content can do.
상기 제1 화합물과 제2 화합물은 중량비로서 1 : 0.2 내지 0.6일 수 있고, 구체적으로 1:0.25 내지 0.5일 수 있다. The first compound and the second compound may be in a weight ratio of 1: 0.2 to 0.6, specifically 1: 0.25 to 0.5.
상기 제1 화합물과 제2 화합물이 1 : 0.2 내지 0.6의 중량비를 만족할 경우, 겔 폴리머 전해질용 조성물의 겔화가 보다 원활하게 이루어질 수 있고, 고온 저장 특성이 향상되어 고온 저장시 전지의 두께 증가를 감소시킬 수 있으며, 호핑 현상을 보다 용이하게 수행되어 중합반응으로 생성되는 겔 폴리머 전해질의 이온 이동도가 높아짐으로써 출력 특성이 향상될 수 있다.When the first compound and the second compound satisfies the weight ratio of 1: 0.2 to 0.6, gelation of the gel polymer electrolyte composition can be made more smoothly, and the high temperature storage property is improved to reduce the increase in thickness of the battery during high temperature storage. In addition, the hopping phenomenon may be more easily performed to increase the ion mobility of the gel polymer electrolyte produced by the polymerization reaction, thereby improving output characteristics.
또한, 본 발명의 일 실시예에 따르면, 상기 겔 폴리머 전해질용 조성물에 상기 혼합 화합물을 포함하는 경우, 양극에서 용출된 금속이온이 음극에서 석출되는 일반 전해액을 사용한 경우와는 달리, 양극에서 용출된 금속이온이 상기 혼합 화합물과 결합하여 음극에서 금속이 석출 되는 것을 경감시킬 수 있다. 이로써 리튬 이차 전지의 충방전 효율을 향상시킬 수 있고 양호한 사이클 특성을 나타낼 수 있다. 뿐만 아니라, 상기 작용기를 갖는 모노머를 포함하는 겔 폴리머 전해질용 조성물을 리튬 이차 전지에 적용할 경우 누액의 위험성이 적으며 난연 특성을 가져 전지의 안정성을 향상시킬 수 있다.In addition, according to an embodiment of the present invention, when the mixed compound is included in the gel polymer electrolyte composition, unlike the case of using a general electrolyte solution in which the metal ions eluted from the positive electrode are precipitated from the negative electrode, eluted from the positive electrode Metal ions can be combined with the mixed compound to reduce the precipitation of metal at the negative electrode. As a result, the charge and discharge efficiency of the lithium secondary battery can be improved and good cycle characteristics can be exhibited. In addition, when the composition for a gel polymer electrolyte including the monomer having the functional group is applied to a lithium secondary battery, there is little risk of leakage and a flame retardant property to improve the stability of the battery.
상기 제1 화합물 및 제2 화합물의 혼합 화합물은 겔 폴리머 전해질용 조성물 총 중량에 대해 0.1 중량% 내지 10 중량%, 바람직하게는 0.5 중량% 내지 5 중량%일 수 있다. 0.1 중량% 미만이면 겔화되기 어려워 겔 폴리머 전해질의 특성이 발현되기 어려울 수 있고, 10 중량%를 초과하면 모노머의 과량 함유로 인해 저항이 증가하여 전지 성능이 저하될 수 있다. The mixed compound of the first compound and the second compound may be 0.1 wt% to 10 wt%, preferably 0.5 wt% to 5 wt%, based on the total weight of the composition for gel polymer electrolyte. If it is less than 0.1% by weight it is difficult to gel the gel polymer electrolyte properties, and if it exceeds 10% by weight may increase the resistance due to the excessive content of the monomer may decrease the battery performance.
본 발명의 일 실시예에 따르면, 상기 제1 화합물 및 제2 화합물을 혼합하여 30℃ 내지 100℃의 온도 범위에서 2분 내지 12시간 동안 반응하여 중합성 모노머를 제조할 수 있다. 이때, 작용기를 갖는 모노머와 분지형 모노머의 함량비는 예를 들어 1:18 내지 1:75의 중량비일 수 있으나, 이에 한정되는 것은 아니다.According to one embodiment of the present invention, the first compound and the second compound may be mixed to react for 2 minutes to 12 hours in a temperature range of 30 ℃ to 100 ℃ to prepare a polymerizable monomer. In this case, the content ratio of the monomer having a functional group and the branched monomer may be, for example, a weight ratio of 1:18 to 1:75, but is not limited thereto.
이러한 겔 폴리머 전해질에서는 리튬 이온이 크기가 작아 직접적인 이동이 상대적으로 수월할 뿐만 아니라, 도 1과 같이 전해액 내에서 호핑(hopping) 현상으로 이동하기 쉽다.In such a gel polymer electrolyte, lithium ions are small in size, and thus, are not only relatively easy to move directly, but also easily move to a hopping phenomenon in the electrolyte as shown in FIG. 1.
본 발명의 일 실시예에 따른 전해질용 조성물에 포함되는 상기 이온화 가능한 리튬염은 예를 들어, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiN(C2F5SO2)2, LiN(CF3SO2)2, CF3SO3Li, LiC(CF3SO2)3 및 LiC4BO8로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물일 수 있으며, 이에 한정되는 것은 아니다.The ionizable lithium salts included in the electrolyte composition according to an embodiment of the present invention may be, for example, LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiClO 4 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) 2 , CF 3 SO 3 Li, LiC (CF 3 SO 2 ) 3 And LiC 4 BO 8 It may be any one selected from the group consisting of or a mixture of two or more thereof. It is not.
또한, 본 발명의 일 실시예에 따라 사용되는 전해액 용매로는 리튬 이차 전지용 전해액에 통상적으로 사용되는 것들을 제한 없이 사용할 수 있으며, 예를 들면 에테르, 에스테르, 아미드, 선형 카보네이트 또는 환형 카보네이트 등을 각각 단독으로 또는 2종 이상 혼합하여 사용할 수 있다.In addition, as the electrolyte solvent used according to an embodiment of the present invention, those conventionally used in the electrolyte for lithium secondary batteries may be used without limitation, and for example, ether, ester, amide, linear carbonate, or cyclic carbonate may be used alone. Or two or more kinds thereof can be mixed.
그 중에서도 대표적으로 환형 카보네이트, 선형 카보네이트 또는 이들의 혼합물인 카보네이트 화합물을 포함할 수 있다. Among them, carbonate compounds which are typically cyclic carbonates, linear carbonates or mixtures thereof may be included.
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 어느 하나 또는 이들 중 2종 이상의 혼합물을 들 수 있다. 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 선택된 어느 하나 또는 이들 중 2종 이상의 혼합물 등이 대표적으로 사용될 수 있으나, 이에 한정되는 것은 아니다. 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 Carbonate, vinylene carbonate, and any one selected from the group consisting of halides thereof, or a mixture of two or more thereof. In addition, specific examples of the linear carbonate compound include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC) and ethylpropyl carbonate (EPC). Any one selected from the group consisting of, or a mixture of two or more thereof may be representatively used, but is not limited thereto.
특히, 상기 카보네이트계 전해액 용매 중 환형 카보네이트인 프로필렌 카보네이트 및 에틸렌 카보네이트는 고점도의 유기 용매로서 유전율이 높아 전해액 내의 리튬염을 잘 해리시키므로 바람직하게 사용될 수 있으며, 이러한 환형 카보네이트에 에틸메틸 카보네이트, 디에틸 카보네이트 또는 디메틸 카보네이트와 같은 저점도, 저유전율 선형 카보네이트를 적당한 비율로 혼합하여 사용하면 높은 전기 전도율을 가지는 전해액을 만들 수 있어서 더욱 바람직하게 사용될 수 있다. In particular, propylene carbonate and ethylene carbonate, which are cyclic carbonates in the carbonate electrolyte solvent, may be preferably used because they have high dielectric constants and dissociate lithium salts in the electrolyte well, such as ethylmethyl carbonate and diethyl carbonate. Alternatively, when a low viscosity, low dielectric constant linear carbonate such as dimethyl carbonate is mixed and used in an appropriate ratio, an electrolyte having high electrical conductivity can be made, and thus it can be used more preferably.
또한, 상기 전해액 용매 중 에스테르로는 메틸 아세테이트, 에틸 아세테이트, 프로필 아세테이트, 메틸 프로피오네이트, 에틸 프로피오네이트, γ-부티로락톤, γ-발레로락톤, γ-카프로락톤, α-발레로락톤 및 ε-카프로락톤으로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물을 사용할 수 있으나, 이에 한정되는 것은 아니다. In addition, the ester in the electrolyte solvent is methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, α-valerolactone And ε-caprolactone, but any one selected from the group consisting of, or a mixture of two or more thereof may be used, but is not limited thereto.
본 발명에 있어서, 중합 개시제는 당 업계에 알려진 통상적인 중합 개시제가 사용될 수 있다.In the present invention, a polymerization initiator may be used a conventional polymerization initiator known in the art.
상기 중합 개시제의 비제한적인 예로는 벤조일 퍼옥사이드(benzoyl peroxide), 아세틸 퍼옥사이드(acetyl peroxide), 디라우릴 퍼옥사이드(dilauryl peroxide), 디-tert-부틸 퍼옥사이드(di-tert-butyl peroxide), t-부틸 퍼옥시-2-에틸-헥사노에이트(t-butyl peroxy-2-ethyl-hexanoate), 큐밀 하이드로퍼옥사이드(cumyl hydroperoxide) 및 하이드로겐 퍼옥사이드(hydrogen peroxide) 등의 유기과산화물류나 히드로과산화물류와 2,2'-아조비스(2-시아노부탄), 2,2'-아조비스(메틸부티로니트릴), AIBN(2,2'-Azobis(iso-butyronitrile)) 및 AMVN(2,2'-Azobisdimethyl-Valeronitrile) 등의 아조 화합물류 등이 있으나, 이에 한정되지 않는다.Non-limiting examples of the polymerization initiator are benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-tert-butyl peroxide, organic peroxides and hydros such as t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide, and hydrogen peroxide Peroxides with 2,2'-azobis (2-cyanobutane), 2,2'-azobis (methylbutyronitrile), AIBN (2,2'-Azobis (iso-butyronitrile)) and AMVN (2 And azo compounds such as 2'-Azobisdimethyl-Valeronitrile), but are not limited thereto.
상기 중합 개시제는 전지 내에서 열, 비제한적인 예로서 30℃ 내지 100℃의 열에 의해 분해되거나 상온(5℃ 내지 30℃)에서 분해되어 라디칼을 형성하고, 자유라디칼 중합에 의해 중합성 모노머와 반응하여 겔 폴리머 전해질을 형성할 수 있다.The polymerization initiator is decomposed by heat in the cell, by way of non-limiting example, 30 ° C. to 100 ° C. or at room temperature (5 ° C. to 30 ° C.) to form radicals, and react with the polymerizable monomer by free radical polymerization. To form a gel polymer electrolyte.
또한, 상기 중합 개시제는 겔 폴리머 전해질용 조성물 총 중량에 대해 0.01 중량% 내지 2 중량%의 양으로 사용될 수 있다. 중합 개시제가 2 중량%를 초과하면 겔 폴리머 전해질용 조성물을 전지 내에 주액하는 도중 겔화가 너무 빨리 일어나거나 미반응 개시제가 남아 나중에 전지 성능에 악영향을 미치는 단점이 있고, 반대로 중합 개시제가 0.01 중량% 미만이면 겔화가 잘 이루어지지 않는 문제가 있다.In addition, the polymerization initiator may be used in an amount of 0.01% by weight to 2% by weight based on the total weight of the composition for gel polymer electrolyte. If the polymerization initiator is more than 2% by weight, gelation may occur too quickly or the unreacted initiator remains after the gel polymer electrolyte composition is injected into the battery, which adversely affects the battery performance. Conversely, the polymerization initiator is less than 0.01% by weight. There is a problem that the gelation is not well done.
본 발명의 일 실시예에 따른 겔 폴리머 전해질용 조성물은 상기 기재된 성분들 이외에, 당 업계에 알려진 기타 첨가제 등을 선택적으로 함유할 수 있다.The gel polymer electrolyte composition according to an embodiment of the present invention may optionally contain other additives known in the art, in addition to the components described above.
본 발명의 일 실시예에 따르면 양극; 음극; 분리막; 및 겔 폴리머 전해질을 포함하는 리튬 이차 전지에 있어서, 상기 겔 폴리머 전해질은 상기 겔 폴리머 전해질용 조성물을 중합시켜 형성된 것을 특징으로 하는 리튬 이차 전지를 제공한다. 본 발명의 일 실시예에 따른 겔 폴리머 전해질은 당 업계에 알려진 통상적인 방법에 따라 겔 폴리머 전해질용 조성물을 중합시켜 형성된 것일 수 있다. 예를 들면, 겔 폴리머 전해질은 이차 전지의 내부에서 상기 겔 폴리머 전해질용 조성물을 in-situ 중합하여 형성될 수 있다.According to an embodiment of the present invention; cathode; Separator; And a lithium secondary battery comprising a gel polymer electrolyte, wherein the gel polymer electrolyte provides a lithium secondary battery, characterized in that formed by polymerizing the composition for the gel polymer electrolyte. Gel polymer electrolyte according to an embodiment of the present invention may be formed by polymerizing the composition for gel polymer electrolyte according to a conventional method known in the art. For example, the gel polymer electrolyte may be formed by in-situ polymerization of the composition for gel polymer electrolyte in the secondary battery.
보다 바람직한 일 실시 형태를 들면, (a) 양극, 음극, 및 상기 양극과 음극 사이에 개재(介在)된 분리막으로 이루어진 전극 조립체를 전지 케이스에 삽입하는 단계 및 (b) 상기 전지 케이스에 본 발명에 따른 겔 폴리머 전해질용 조성물을 주입한 후 중합시켜 겔 폴리머 전해질을 형성하는 단계를 포함할 수 있다.For a more preferred embodiment, (a) inserting an electrode assembly consisting of a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode in the battery case and (b) the present invention in the battery case Injecting the composition for the gel polymer electrolyte according to the polymerization may include the step of forming a gel polymer electrolyte.
리튬 이차 전지 내 in-situ 중합 반응은 열 중합을 통해 진행될 수 있다. 이때, 중합 시간은 대략 2분 내지 12시간 정도 소요되며, 열 중합 온도는 30 내지 100℃가 될 수 있다.The in-situ polymerization reaction in the lithium secondary battery may proceed through thermal polymerization. At this time, the polymerization time takes about 2 minutes to 12 hours, the thermal polymerization temperature may be 30 to 100 ℃.
이와 같은 중합 반응에 의한 겔화를 거치게 되면 겔 폴리머 전해질이 형성된다. 구체적으로는, 중합성 모노머가 중합 반응에 의해 서로 가교된 올리고머가 형성되며, 전해질 염이 전해액 용매에 해리된 액체 전해액이 상기 형성된 올리고머 내에 균일하게 함침될 수 있다.When gelation by such a polymerization reaction is carried out, a gel polymer electrolyte is formed. Specifically, oligomers in which the polymerizable monomers are crosslinked with each other by a polymerization reaction are formed, and the liquid electrolyte in which the electrolyte salt is dissociated in the electrolyte solvent can be uniformly impregnated in the formed oligomer.
본 발명의 일 실시예에 따른 상기 올리고머는 하기 화학식 1 및 2로 표시되는 올리고머의 혼합된 형태일 수 있다.The oligomer according to an embodiment of the present invention may be a mixed form of the oligomer represented by the formula (1) and (2).
[화학식 1][Formula 1]
Figure PCTKR2015010416-appb-I000003
Figure PCTKR2015010416-appb-I000003
여기서 상기 n, m은 각각 1 내지 20의 정수이고, 상기 R1 내지 R5는 각각 독립적으로 수소, 또는 -CO(CH2)3COO-(CH2CH2O)x-CH3인 것이고, x는 1 내지 100의 정수이며, 상기 R1 내지 R5 중 적어도 (3) 이상은 -CO(CH2)3COO-(CH2CH2O)X-CH3이다.Wherein n and m are each an integer of 1 to 20, and each of R 1 to R 5 is independently hydrogen or —CO (CH 2 ) 3 COO— (CH 2 CH 2 O) x—CH 3 , x is an integer from 1 to 100, wherein R 1 to R at least 3 or more of the 5, -CO (CH 2) 3 COO- ( CH 2 CH 2 O) x -CH 3.
[화학식 2][Formula 2]
Figure PCTKR2015010416-appb-I000004
Figure PCTKR2015010416-appb-I000004
여기서 상기 a는 1 내지 100의 정수이다.Wherein a is an integer from 1 to 100.
본 발명의 일 실시예에 따른 상기 리튬 이차 전지는 충전 전압이 3.0V 내지 5.0V 범위로, 일반전압 및 고전압 영역 모두에서 리튬 이차 전지의 용량 특성이 우수하다.The lithium secondary battery according to an embodiment of the present invention has a charge voltage of 3.0V to 5.0V, and excellent capacity characteristics of the lithium secondary battery in both a normal voltage and a high voltage region.
본 발명의 일 실시예에 따르면, 상기 리튬 이차 전지의 전극은 당 분야에 알려져 있는 통상적인 방법으로 제조할 수 있다. 예를 들면, 전극 활물질에 용매, 필요에 따라 바인더, 도전재, 분산제를 혼합 및 교반하여 슬러리를 제조한 후 이를 금속 재료의 집전체에 도포(코팅)하고 압축한 뒤 건조하여 전극을 제조할 수 있다.According to an embodiment of the present invention, the electrode of the lithium secondary battery may be manufactured by a conventional method known in the art. For example, a slurry may be prepared by mixing and stirring a solvent, a binder, a conductive material, and a dispersant in an electrode active material, and then applying the coating (coating) to a current collector of a metal material, compressing, and drying the electrode to prepare an electrode. have.
본 발명의 일 실시예에 따르면, 상기 양극에 있어서 양극 활물질은 일반전압 또는 고전압에 적용할 수 있고, 리튬을 가역적으로 인터칼레이션/디인터칼레이션 할 수 있는 화합물이면 제한없이 사용될 수 있다.According to an embodiment of the present invention, the positive electrode active material in the positive electrode may be applied to a general voltage or a high voltage, and may be used without limitation as long as it is a compound capable of reversibly intercalating / deintercalating lithium.
본 발명의 일 실시예에 따른 리튬 이차 전지에 있어서, 일반전압에 적용될 수 있는 양극 활물질은, 예를 들면 LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi1 -yCoyO2(O=y<1), LiCo1 - yMnyO2(O=y<1), LiNi1 - yMnyO2(O=y<1), 및 Li[NiaCobMnc]O2(0 < a, b, c = 1, a+b+c=1)로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물을 포함할 수 있으며, 이들로 한정되는 것은 아니다. 또한, 이러한 산화물(oxide) 외에 황화물(sulfide), 셀렌화물(selenide) 및 할로겐화물(halide) 등도 포함될 수 있다.In the lithium secondary battery according to an embodiment of the present invention, the positive electrode active material which can be applied to a general voltage is, for example, LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , LiNi 1 -y Co y O 2 ( O = y <1), LiCo 1 - y Mn y O 2 (O = y <1), LiNi 1 - y Mn y O 2 (O = y <1), and Li [Ni a Co b Mn c ] O 2 (0 <a, b, c = 1, a + b + c = 1) may include any one or a mixture of two or more thereof selected from the group consisting of It is not limited to these. In addition, such oxides may include sulfides, selenides, and halides.
한편, 본 발명의 일 실시예에 따른 리튬 이차 전지에 있어서, 상기 음극 활물질로는 통상적으로 리튬 이온이 흡장 및 방출될 수 있는 탄소재, 리튬 금속, 규소 또는 주석 등을 사용할 수 있다. 바람직하게는 탄소재를 사용할 수 있는데, 탄소재로는 저결정 탄소 및 고결정성 탄소 등이 모두 사용될 수 있다. 저결정성 탄소로는 연화탄소(soft carbon) 및 경화탄소(hard carbon)가 대표적이며, 고결정성 탄소로는 천연 흑연, 키시흑연(Kish graphite), 열분해 탄소(pyrolytic carbon), 액정피치계 탄소섬유(mesophase pitch based carbon fiber), 탄소 미소구체(meso-carbon microbeads), 액정피치(Mesophase pitches) 및 석유와 석탄계 코크스(petroleum or coal tar pitch derived cokes) 등의 고온 소성탄소가 대표적이다. On the other hand, in the lithium secondary battery according to an embodiment of the present invention, as the negative electrode active material, a carbon material, lithium metal, silicon or tin, etc. which can normally occlude and release lithium ions may be used. Preferably, a carbon material may be used, and as the carbon material, both low crystalline carbon and high crystalline carbon may be used. Soft crystalline carbon and hard carbon are typical low crystalline carbon, and high crystalline carbon is natural graphite, Kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber. High temperature calcined carbon such as (mesophase pitch based carbon fiber), meso-carbon microbeads, Mesophase pitches and petroleum or coal tar pitch derived cokes.
상기 양극 및/또는 음극은 바인더와 용매, 필요에 따라 통상적으로 사용될 수 있는 도전재와 분산제를 혼합 및 교반하여 슬러리를 제조한 후 이를 집전체에 도포하고 압축하여 음극을 제조할 수 있다. The positive electrode and / or negative electrode may be prepared by mixing and stirring a binder, a solvent, a conductive material and a dispersant, which may be commonly used as necessary, to prepare a slurry, and then applying the same to a current collector and compressing the negative electrode.
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.
또한, 분리막으로는 종래에 분리막으로 사용된 통상적인 다공성 고분자 필름, 예를 들어 에틸렌 단독중합체, 프로필렌 단독중합체, 에틸렌/부텐 공중합체, 에틸렌/헥센 공중합체 및 에틸렌/메타크릴레이트 공중합체 등과 같은 폴리올레핀계 고분자로 제조한 다공성 고분자 필름을 단독으로 또는 이들을 적층하여 사용할 수 있으며, 또는 통상적인 다공성 부직포, 예를 들어 고융점의 유리 섬유, 폴리에틸렌테레프탈레이트 섬유 등으로 된 부직포를 사용할 수 있으나, 이에 한정되는 것은 아니다.In addition, as the separator, conventional porous polymer films conventionally used as separators, for example, polyolefins such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer, etc. The porous polymer film made of the polymer may be used alone or by laminating them, or a conventional porous nonwoven fabric, for example, a non-woven fabric made of high melting point glass fiber, polyethylene terephthalate fiber, or the like may be used. It is not.
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 the exemplary embodiment of the present invention is not particularly limited, but may be cylindrical, square, 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.
실시예Example
실시예 1 : 겔 폴리머 전해질용 조성물 제조Example 1 Preparation of Composition for Gel Polymer Electrolyte
에틸렌 카보네이트(EC) : 에틸메틸카보네이트(EMC) = 1:2(부피비)의 조성을 갖는 비수 전해액 용매에 LiPF6를 1M 농도가 되도록 용해하여 전해액을 준비하였다. 상기 전해액의 중량을 합한 전해질용 조성물 총 중량 대비 중합 개시제로서 t-부틸 퍼옥시-2-에틸헥사노에이트 0.25 중량%를 첨가하고, 제1 화합물로서 폴리(에틸렌 이민)-그라프트-폴리(에틸렌 글리콜)(PEI-PEG) 2 중량%를 첨가한 다음, 제2 화합물로서 폴리에틸렌글리콜 다이글리시딜 에테르를 제1 화합물 대비 1/3 중량%의 양으로 첨가하였다. 이로써 겔 폴리머 전해질용 조성물을 제조하였다.An electrolyte solution was prepared by dissolving LiPF 6 in a non-aqueous electrolyte solvent having a composition of ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1: 2 (volume ratio) to a concentration of 1 M. 0.25 weight% of t-butyl peroxy-2-ethylhexanoate is added as a polymerization initiator with respect to the total weight of the composition for electrolytes which summed the weight of the said electrolyte solution, and poly (ethylene imine) -graft-poly (ethylene Glycol) (PEI-PEG) 2% by weight was added, followed by polyethylene glycol diglycidyl ether as the second compound in an amount of 1/3% by weight relative to the first compound. This produced a composition for gel polymer electrolyte.
실시예 2 : 겔 폴리머 전해질용 조성물 제조Example 2 Preparation of Composition for Gel Polymer Electrolyte
상기 실시예 1에서, 제1 화합물로서 폴리(에틸렌 이민)-그라프트-폴리(에틸렌 글리콜)(PEI-PEG)을 5 중량%의 양으로, 제2 화합물로서 폴리에틸렌글리콜 다이글리시딜 에테르를 제1 화합물 대비 1/3 중량%의 양으로 사용한 것으로 제외하고는, 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물을 제조하였다.In Example 1, the poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) as the first compound in an amount of 5% by weight, and polyethylene glycol diglycidyl ether as the second compound A gel polymer electrolyte composition was prepared in the same manner as in Example 1, except that the compound was used in an amount of 1/3 wt% based on 1 compound.
실시예 3 : 겔 폴리머 전해질용 조성물 제조Example 3 Preparation of Composition for Gel Polymer Electrolyte
상기 실시예 1에서, 제1 화합물로서 폴리(에틸렌 이민)-그라프트-폴리(에틸렌 글리콜)(PEI-PEG)을 대신하여 폴리(에틸렌 이민)(PEI)을 사용한 것을 제외하고는, 실시예 1과 마찬가지의 방법으로 겔 폴리머 전해질용 조성물을 제조하였다.Example 1, except that poly (ethylene imine) (PEI) was used in place of poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) as the first compound. In the same manner as in the gel polymer electrolyte composition was prepared.
실시예 4 : 겔 폴리머 전해질용 조성물 제조Example 4 Preparation of Composition for Gel Polymer Electrolyte
상기 실시예 2에서, 제1 화합물로서 폴리(에틸렌 이민)-그라프트-폴리(에틸렌 글리콜)(PEI-PEG)을 대신하여 폴리(에틸렌 이민)(PEI)을 사용한 것을 제외하고는, 실시예 2와 마찬가지의 방법으로 겔 폴리머 전해질용 조성물을 제조하였다.Example 2, except that poly (ethylene imine) (PEI) was used instead of poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) as the first compound. In the same manner as in the gel polymer electrolyte composition was prepared.
실시예 5 : 이차 전지의 제조Example 5 Fabrication of Secondary Battery
양극 제조Anode manufacturing
양극 활물질로 LiCoO2 94 중량%, 도전재로 카본 블랙(carbon black) 3 중량%, 바인더로 PVdF 3 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.94% by weight of LiCoO 2 as a positive electrode active material, 3% by weight carbon black as a conductive material and 3% by weight PVdF as a binder were added to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare a positive electrode mixture slurry. 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.
음극 제조Cathode manufacturing
음극 활물질로 탄소 분말, 바인더로 PVdF, 도전재로 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.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 material 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.
전지 제조Battery manufacturing
상기 양극, 음극 및 폴리프로필렌/폴리에틸렌/폴리프로필렌 (PP/PE/PP) 3층으로 이루어진 분리막을 이용하여 전지를 조립하였으며, 조립된 전지에 상기 실시예 1에서 제조된 겔 폴리머 전해질용 조성물을 주입한 후 80 ℃에서 2~30분간 가열하여 이차 전지를 제조하였다.The battery was assembled using a separator consisting of the positive electrode, the negative electrode, and three layers of polypropylene / polyethylene / polypropylene (PP / PE / PP), and the gel polymer electrolyte composition prepared in Example 1 was injected into the assembled battery. Then, the secondary battery was manufactured by heating at 80 ° C. for 2 to 30 minutes.
실시예 6 내지 8 : 이차 전지의 제조Examples 6 to 8: Preparation of Secondary Battery
상기 실시예 5에서, 상기 실시예 1에서 제조된 겔 폴리머 전해질용 조성물을 대신하여, 각각 상기 실시예 2 내지 4에서 제조된 겔 폴리머 전해질용 조성물을 사용한 것을 제외하고는, 상기 실시예 5와 마찬가지의 방법으로 각각 이차 전지를 제조하였다.In Example 5, except for using the gel polymer electrolyte composition prepared in Examples 2 to 4 instead of the gel polymer electrolyte composition prepared in Example 1, the same as in Example 5 Each secondary battery was manufactured by the method of.
실험예 1 : 겔 전해질 생성 반응 비교Experimental Example 1 gel electrolyte production reaction comparison
상기 실시예 1 내지 4에서 제조된 겔 폴리머 전해질용 조성물을 65℃에서 경화시켜 겔 화(gelation)가 이루어지는지를 관찰하였으며, 그 결과를 하기 표 1에 나타내었다. The gel polymer electrolyte composition prepared in Examples 1 to 4 was cured at 65 ° C. to observe whether gelation occurred, and the results are shown in Table 1 below.
제1 화합물First compound 제2 화합물Second compound 첨가량Amount 겔화 여부Gelation
실시예1Example 1 폴리(에틸렌 이민)-그라프트-폴리(에틸렌 글리콜)(PEI-PEG)Poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) 폴리에틸렌글리콜 다이글리시딜 에테르Polyethyleneglycol Diglycidyl Ether 제1 화합물:2 중량%제2 화합물:제1 화합물 대비 1/3 중량%1st compound: 2 weight% 2nd compound: 1/3 weight% compared with a 1st compound 겔화됨Gelled
실시예2Example 2 폴리(에틸렌 이민)-그라프트-폴리(에틸렌 글리콜)(PEI-PEG)Poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) 폴리에틸렌글리콜 다이글리시딜 에테르Polyethyleneglycol Diglycidyl Ether 제1 화합물:5 중량%제2 화합물:제1 화합물 대비 1/3 중량%1st compound: 5 weight% 2nd compound: 1/3 weight% compared with a 1st compound 겔화됨Gelled
실시예3Example 3 폴리(에틸렌 이민)(PEI)Poly (ethylene imine) (PEI) 폴리에틸렌글리콜 다이글리시딜 에테르Polyethyleneglycol Diglycidyl Ether 제1 화합물:2 중량%제2 화합물:제1 화합물 대비 1/3 중량%1st compound: 2 weight% 2nd compound: 1/3 weight% compared with a 1st compound 겔화됨Gelled
실시예4Example 4 폴리(에틸렌 이민)(PEI)Poly (ethylene imine) (PEI) 폴리에틸렌글리콜 다이글리시딜 에테르Polyethyleneglycol Diglycidyl Ether 제1 화합물:5 중량%제2 화합물:제1 화합물 대비 1/3 중량%1st compound: 5 weight% 2nd compound: 1/3 weight% compared with a 1st compound 겔화되지 않음Not gelated
상기 표 1에 나타낸 바와 같이, 제1 화합물로서 폴리(에틸렌 이민)-그라프트-폴리(에틸렌 글리콜)(PEI-PEG)을 사용하고, 제2 화합물로서 폴리에틸렌글리콜 다이글리시딜 에테르를 사용한 혼합 화합물을 포함하는 겔 폴리머 전해질용 조성물은 상기 제1 화합물의 함량이 2 중량%이고, 제2 화합물의 함량이 상기 제1 화합물 대비 1/3 중량%인 경우(실시예 1) 및 상기 제1 화합물이 5 중량%이고, 제2 화합물의 함량이 상기 제1 화합물 대비 1/3 중량%인 경우 모두 원활히 겔화가 이루어졌다. 반면, 제1 화합물로서 폴리(에틸렌 이민)(PEI)을 사용하고, 제2 화합물로서 폴리에틸렌글리콜 다이글리시딜 에테르를 사용한 혼합 화합물을 포함하는 겔 폴리머 전해질용 조성물의 경우는 기 제1 화합물의 함량이 2 중량%이고, 제2 화합물의 함량이 상기 제1 화합물 대비 1/3 중량%인 실시예 3의 경우는 원활히 겔화가 이루어졌지만, 제1 화합물이 5 중량%이고, 제2 화합물의 함량이 상기 제1 화합물 대비 1/3 중량%인 실시예 4의 경우는 겔화가 이루어지지 않았다. As shown in Table 1, a mixed compound using poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) as the first compound and polyethylene glycol diglycidyl ether as the second compound The composition for a gel polymer electrolyte comprising a 2% by weight of the first compound, the content of the second compound is 1/3% by weight compared to the first compound (Example 1) and the first compound 5% by weight and the content of the second compound was 1/3 of the weight of the first compound was all gelled smoothly. On the other hand, in the case of a composition for gel polymer electrolyte comprising a mixed compound using poly (ethylene imine) (PEI) as the first compound and polyethylene glycol diglycidyl ether as the second compound, the content of the first compound Is 2% by weight and the content of the second compound is 1/3% by weight compared to the first compound in the case of gelation was smooth, but the first compound is 5% by weight, the content of the second compound In Example 4 that is 1/3% by weight of the first compound, gelation was not performed.
실험예Experimental Example 2 : 이차전지의 용량 평가 2: capacity evaluation of secondary battery
실시예 5 내지 7에서 제조된 각각의 이차 전지를 0.1 C(단위: mA/g)의 속도(C-rate)로 전압이 4.4 V가 될 때까지 충전시킨 다음, 4.4 V의 정전압 조건에서 전류가 0.05 C가 될 때까지 더 충전시켰다. 이후, 10분간 휴지(rest)하였다. 이어서, 상기 각 전지를 0.3 C의 속도로 전압이 2.8 V가 될 때까지 방전시켰다. 각각의 방전 용량을 측정하여 결과를 표 2에 나타내었으며, 전해질의 겔 화가 이루어지지 않은 실시예 8의 전지에 대해서는 실험을 진행하지 않았다.Each secondary battery prepared in Examples 5 to 7 was charged at a C-rate of 0.1 C (unit: mA / g) until the voltage became 4.4 V, and then the current was Charged further until 0.05 C. Then rest for 10 minutes. Then, each battery was discharged at a rate of 0.3 C until the voltage became 2.8 V. Each discharge capacity was measured, and the results are shown in Table 2, and the experiment of the battery of Example 8 without gelation of the electrolyte was not conducted.
설계 용량Design capacity 실시예 5Example 5 실시예 6Example 6 실시예 7Example 7
0.3 C 방전0.3 C discharge 37.8 mAh37.8 mAh 36.1 mAh36.1 mAh 35.7 mAh35.7 mAh 35.2 mAh35.2 mAh
표 2에서 확인할 수 있는 바와 같이, 제1 화합물과 제2 화합물의 혼합 화합물을 포함하는 겔 폴리머 전해질용 조성물을 사용한 이차전지는 우수한 용량 특성을 나타냈으며, 특히 제1 화합물로서 폴리에틸렌 글리콜 작용기를 포함하는 아민계 화합물인 폴리(에틸렌 이민)-그라프트-폴리(에틸렌 글리콜)(PEI-PEG)을 포함할 경우(실시예 5)는, 폴리에틸렌 글리콜 작용기를 포함하지 않는 아민계 화합물인 폴리(에틸렌 이민)(PEI)을 포함할 경우(실시예 7)에 비하여 제1 화합물 및 제2 화합물의 함량이 동일함에도 불구하고, 더욱 우수한 용량 특성을 나타냄을 알 수 있었다. As can be seen in Table 2, the secondary battery using the composition for gel polymer electrolyte containing the mixed compound of the first compound and the second compound exhibited excellent capacity characteristics, in particular, containing a polyethylene glycol functional group as the first compound. In the case of containing poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG) which is an amine compound (Example 5), poly (ethylene imine) which is an amine compound containing no polyethylene glycol functional group Although the content of the first compound and the second compound were the same as compared with the case of (PEI) (Example 7), it was found to exhibit better capacity characteristics.
실험예 3 : 고온 저장 특성 평가Experimental Example 3 Evaluation of High Temperature Storage Characteristics
실시예 5 내지 7에서 제조된 각각의 이차 전지의 두께를 측정한 후, 상기 각각의 이차 전지를 온도 60℃의 챔버에 넣어 3주간 보관한 다음, 다시 두께를 측정하여 보관 전의 두께와 비교하여 계산한 후, 그 결과를 도 2에 나타내었다. After measuring the thickness of each secondary battery prepared in Examples 5 to 7, the secondary battery was stored in a chamber at a temperature of 60 ° C for 3 weeks, and then again measured by measuring the thickness and compared with the thickness before storage After that, the results are shown in FIG. 2.
도 2를 참조하면, 제1 화합물로서 폴리에틸렌 글리콜 작용기를 포함하는 아민계 화합물인 폴리(에틸렌 이민)-그라프트-폴리(에틸렌 글리콜)(PEI-PEG)을 사용하여 겔화시킨 이차 전지(실시예 6)의 경우, 폴리에틸렌 글리콜 작용기를 포함하지 않는 아민계 화합물인 폴리(에틸렌 이민)(PEI)을 사용하여 겔화시킨 이차 전지(실시예 7)에 비해 고온 저장시 두께 증가량이 감소되어 우수한 고온 저장 성능을 나타내었다.Referring to FIG. 2, a secondary battery gelled using poly (ethylene imine) -graft-poly (ethylene glycol) (PEI-PEG), which is an amine compound containing polyethylene glycol functional groups, as a first compound (Example 6 ), Compared to the secondary battery (Example 7) gelled using poly (ethylene imine) (PEI), which is an amine compound containing no polyethylene glycol functional group, the increase in thickness during high temperature storage was reduced, resulting in excellent high temperature storage performance. Indicated.

Claims (13)

  1. 전해액 용매, 리튬염, 중합 개시제; 및 제1 화합물과 제2 화합물의 혼합 화합물을 포함하는 겔 폴리머 전해질용 조성물.Electrolyte solution solvent, lithium salt, polymerization initiator; And a mixed compound of a first compound and a second compound.
  2. 제 1 항에 있어서,The method of claim 1,
    상기 제1 화합물은 작용기로서 폴리에틸렌 글리콜을 포함하는 아민계 화합물인 겔 폴리머 전해질용 조성물.The first compound is an amine-based compound containing a polyethylene glycol as a functional group for a gel polymer electrolyte composition.
  3. 제 1 항에 있어서, The method of claim 1,
    상기 제2 화합물은 에폭시계 화합물인 겔 폴리머 전해질용 조성물.The second compound is a gel polymer electrolyte composition which is an epoxy compound.
  4. 제 1 항에 있어서, The method of claim 1,
    상기 혼합 화합물은 조성물 총 중량에 대해 0.1 중량% 내지 10 중량%의 양으로 포함된 겔 폴리머 전해질용 조성물.The mixed compound is a composition for a gel polymer electrolyte contained in an amount of 0.1% to 10% by weight relative to the total weight of the composition.
  5. 제 1항에 있어서,The method of claim 1,
    상기 제1 화합물과 제2 화합물은 중량비로서 1 : 0.2 내지 0.6인 겔 폴리머 전해질용 조성물.The first compound and the second compound is a gel polymer electrolyte composition in a weight ratio of 1: 0.2 to 0.6.
  6. 제 1 항에 있어서, The method of claim 1,
    상기 리튬염은 LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiN(C2F5SO2)2, LiN(CF3SO2)2, CF3SO3Li, LiC(CF3SO2)3 및 LiC4BO8로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물인 겔 폴리머 전해질용 조성물.The lithium salt may be LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiClO 4 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) 2 , CF 3 SO 3 Li, LiC (CF 3 SO 2 ) A composition for gel polymer electrolyte, which is any one selected from the group consisting of 3 and LiC 4 BO 8 or a mixture of two or more thereof.
  7. 제 1 항에 있어서, The method of claim 1,
    상기 전해액 용매는 선형 카보네이트, 환형 카보네이트 또는 이들의 조합인 겔 폴리머 전해질용 조성물.The electrolyte solution is a composition for a gel polymer electrolyte is a linear carbonate, cyclic carbonate or a combination thereof.
  8. 제 7 항에 있어서, The method of claim 7, wherein
    상기 선형 카보네이트는 디메틸 카보네이트, 디에틸 카보네이트, 디프로필 카보네이트, 에틸메틸 카보네이트, 메틸프로필 카보네이트 및 에틸프로필 카보네이트로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물을 포함하고, 상기 환형 카보네이트는 에틸렌 카보네이트, 프로필렌 카보네이트, 1,2-부틸렌 카보네이트, 2,3-부틸렌 카보네이트, 1,2-펜틸렌 카보네이트, 2,3-펜틸렌 카보네이트, 비닐렌 카보네이트, 및 이들의 할로겐화물로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물을 포함하는 겔 폴리머 전해질용 조성물.The linear carbonate includes any one or a mixture of two or more selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylmethyl carbonate, methylpropyl carbonate and ethylpropyl carbonate, wherein the cyclic carbonate is ethylene Carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, and halides thereof A composition for gel polymer electrolyte comprising any one selected or a mixture of two or more thereof.
  9. 제 1 항에 있어서, The method of claim 1,
    상기 중합 개시제는 벤조일 퍼옥사이드(benzoyl peroxide), 아세틸 퍼옥사이드(acetyl peroxide), 디라우릴 퍼옥사이드(dilauryl peroxide), 디-tert-부틸 퍼옥사이드(di-tert-butyl peroxide), t-부틸 퍼옥시-2-에틸-헥사노에이트(t-butyl peroxy-2-ethyl-hexanoate), 큐밀 하이드로퍼옥사이드(cumyl hydroperoxide) 및 하이드로겐 퍼옥사이드(hydrogen peroxide) 등의 유기과산화물류; 히드로과산화물류와 2,2'-아조비스(2-시아노부탄), 2,2'-아조비스(메틸부티로니트릴), AIBN(2,2'-Azobis(iso-butyronitrile)) 및 AMVN(2,2'-Azobisdimethyl-Valeronitrile) 등의 아조 화합물류로 이루어진 군에서 선택되는 1종 이상인 겔 폴리머 전해질용 조성물.The polymerization initiator is benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-tert-butyl peroxide, t-butyl peroxy Organic peroxides, such as t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide and hydrogen peroxide; Hydroperoxides, 2,2'-azobis (2-cyanobutane), 2,2'-azobis (methylbutyronitrile), AIBN (2,2'-Azobis (iso-butyronitrile)) and AMVN ( A composition for gel polymer electrolyte, which is at least one member selected from the group consisting of azo compounds such as 2,2'-Azobisdimethyl-Valeronitrile).
  10. 양극; 음극; 분리막; 및 겔 폴리머 전해질을 포함하는 리튬 이차 전지로서, anode; cathode; Separator; And a lithium secondary battery comprising a gel polymer electrolyte,
    상기 겔 폴리머 전해질은 제 1 항의 겔 폴리머 전해질용 조성물을 중합시켜 형성된 것인 리튬 이차 전지. The gel polymer electrolyte is formed by polymerizing the gel polymer electrolyte composition of claim 1.
  11. 제 10 항에 있어서, The method of claim 10,
    상기 겔 폴리머 전해질은 이하 화학식 1 및 2로 표시되는 올리고머를 포함하는 리튬 이차 전지.The gel polymer electrolyte is a lithium secondary battery comprising an oligomer represented by the formula (1) and (2).
    [화학식 1][Formula 1]
    Figure PCTKR2015010416-appb-I000005
    Figure PCTKR2015010416-appb-I000005
    (여기서 상기 n, m은 각각 1 내지 20의 정수이고, 상기 R1 내지 R5는 각각 독립적으로 수소, 또는 -CO(CH2)3COO-(CH2CH2O)x-CH3인 것이고, x는 1 내지 100의 정수이며, 상기 R1 내지 R5 중 적어도 (3) 이상은 -CO(CH2)3COO-(CH2CH2O)X-CH3이다.) Wherein n and m are each an integer of 1 to 20, and each of R 1 to R 5 is independently hydrogen or —CO (CH 2 ) 3 COO— (CH 2 CH 2 O) x—CH 3 , x is an integer of 1 to 100, and at least (3) or more of the R 1 to R 5 is -CO (CH 2 ) 3 COO- (CH 2 CH 2 O) X -CH 3. )
    [화학식 2][Formula 2]
    Figure PCTKR2015010416-appb-I000006
    Figure PCTKR2015010416-appb-I000006
    (여기서 상기 a는 1 내지 100의 정수이다.)(Where a is an integer of 1 to 100).
  12. 제 10 항에 있어서, The method of claim 10,
    상기 리튬 이차 전지의 충전 전압은 3.0V 내지 5.0V인 리튬 이차 전지.The lithium secondary battery has a charging voltage of 3.0V to 5.0V.
  13. 제 10 항에 있어서, The method of claim 10,
    상기 양극은 양극 활물질을 포함하고, 상기 양극 활물질은 LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi1 - yCoyO2(O=y<1), LiCo1 - yMnyO2(O=y<1), LiNi1 - yMnyO2 (O=y<1), 및 Li[NiaCobMnc]O2 (0 < a, b, c = 1, a+b+c=1)로 이루어진 군에서 선택되는 어느 하나 또는 이들 중 2종 이상의 혼합물인 리튬 이차 전지.The positive electrode includes a positive electrode active material, the positive electrode active material is LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , LiNi 1 - y Co y O 2 (O = y <1), LiCo 1 - y Mn y O 2 (O = y <1), LiNi 1 - y Mn y O 2 (O = y <1), and Li [Ni a Co b Mn c ] O 2 (0 <a, b, c = 1, a + b + c = 1) any one selected from the group consisting of or a mixture of two or more thereof.
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CN111033861A (en) * 2017-11-30 2020-04-17 株式会社Lg化学 Composition for gel polymer electrolyte, gel polymer electrolyte prepared from the composition, and lithium secondary battery comprising the gel polymer electrolyte
US11522219B2 (en) 2017-11-30 2022-12-06 Lg Energy Solution, Ltd. Composition for gel polymer electrolyte, gel polymer electrolyte prepared therefrom, and lithium secondary battery including the same
CN111052481A (en) * 2017-12-01 2020-04-21 株式会社Lg化学 Gel polymer electrolyte composition and lithium secondary battery including the same
CN111052481B (en) * 2017-12-01 2023-06-02 株式会社Lg新能源 Gel polymer electrolyte composition and lithium secondary battery including the same

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