KR20190133534A - Solid electrolyte composition for secondary battery and solid electrolyte - Google Patents

Abstract

The present invention relates to an electrolyte composition comprising a polycarbonate-based polymer and a solid electrolyte. By applying the electrolyte composition, wherein a polycarbonate-based linear polymer in which polyethylene oxides with the molecular weight above a certain value are introduced and polyethylene oxides are blended, provided is the solid electrolyte made of a flexible film which has excellent ion conductivity and can be free-stand at room temperature.

Description

Solid electrolyte composition for secondary batteries and solid electrolyte prepared therefrom {SOLID ELECTROLYTE COMPOSITION FOR SECONDARY BATTERY AND SOLID ELECTROLYTE}

The present invention relates to a solid electrolyte composition for a secondary battery and a solid electrolyte prepared therefrom.

The secondary battery, which is known as a representative of the electrochemical devices, refers to a device that converts external electrical energy into chemical energy and stores it and generates electricity when needed. The term "rechargeable battery" is also used to mean that it can be charged multiple times. Commonly used secondary batteries include lead storage batteries, nickel cadmium batteries (NiCd), nickel hydrogen storage batteries (NiMH), lithium ion batteries (Li-ion), and lithium ion polymer batteries (Li-ion polymer). Secondary batteries offer both economic and environmental advantages over primary batteries that are used once and discarded.

On the other hand, as the wireless communication technology is gradually developed, as the weight reduction of portable devices or automobile accessories and the like is required, the demand for secondary batteries used as energy sources of these devices is increasing.

Currently, secondary batteries are used in places requiring low power, such as devices for helping the vehicle start up, portable devices such as laptops and mobile phones, and uninterruptible power supplies. In particular, as hybrid vehicles and electric vehicles are put to practical use in terms of preventing environmental pollution, researches for reducing manufacturing costs and weights and extending the lifespan by using secondary batteries for such next-generation automobile batteries are emerging.

In general, a secondary battery is manufactured by mounting an electrode assembly composed of a negative electrode, a positive electrode, and a separator inside a pouch-shaped case of a metal can such as a cylinder or a square or an aluminum laminate sheet, and injecting an electrolyte into the electrode assembly.

However, in the case of the secondary battery, since a case having a certain space such as a cylindrical, square or pouch type is required, there are limitations in developing various types of portable devices. Accordingly, there is a need for a new type of secondary battery that is easily deformed. In particular, as an electrolyte included in a secondary battery, an electrolyte having no fear of leakage and excellent ion conductivity is required.

Conventionally, as an electrolyte for an electrochemical device, a liquid electrolyte in which a salt is dissolved in a non-aqueous organic solvent has been mainly used. However, such a liquid electrolyte has a high possibility of deterioration of electrode material and volatilization of an organic solvent, combustion due to an increase in ambient temperature and temperature of the battery itself, leakage of liquid, and various forms of high safety. Difficulties arise in the implementation of electrochemical devices.

In order to solve the problem of the liquid electrolyte, research on the polymer electrolyte is being actively conducted. Polymer electrolytes are largely divided into gel and solid forms. Gel-type polymer electrolyte impregnates a high-boiling liquid electrolyte in a polymer film and fixes it with lithium salts to show conductivity, and contains a large amount of liquid electrolyte, which has similar ionic conductivity as pure liquid electrolyte, but still has a problem of electrochemical stability. Remains.

On the other hand, since the solid polymer electrolyte does not contain a liquid electrolyte, the stability problem related to leakage is improved as well as the chemical and electrochemical stability is high. However, a lot of researches to improve the ion conductivity at room temperature is about 100 times lower than the liquid electrolyte.

Currently, the most widely used material for a solid polymer electrolyte is polyethylene oxide (PEO), which has the ability to conduct lithium ions despite being in a solid phase. However, in the case of the linear PEO polymer electrolyte, the high crystallinity restricts the fluidity of the chain and the low dielectric constant (5.0) does not dissociate a large amount of lithium ions. In addition, the conductivity is very low at room temperature, it is difficult to apply to a lithium secondary battery, the electrochemically stable voltage range of 4.0 V vs Li + / Li is not enough for high-voltage battery material for high energy battery.

In this way, a plasticizer is added to polyethylene oxide to increase the flexibility of the polymer main chain, a low molecular weight ethylene oxide side branch is bonded to a non-hard polymer main chain to lower the crystallinity, or a polyethylene having low molecular weight to a polymer having a crosslinked structure. The method of improving the conductivity by reducing the crystallinity of polyethylene oxide by immobilization has been studied, but there are still limitations.

On the other hand, as the liquid carbonate-based electrolyte is modified into a polycarbonate-based material, attention is focused on forming a stable SEI (Solid Electrolyte Interphase) layer on the electrode. For example, solid electrolytes using poly (carprolactone-co-trimethylene carbonate), poly (propylene carbonate), poly (vinylene carbonate), and poly (ethylene carbonate) have higher ion conductivity and higher lithium ion transition water than PEO-based electrolytes. (Li + transference number).

According to a recent study, it is known that an aliphatic chain or ethylene oxide chain can be introduced between carbonate groups as a polymer containing carbonate functional groups and applied as a solid electrolyte. However, in these studies, there is a problem in that an excessive amount of lithium salt is used in order to exhibit an ionic conductivity of 10 ^-5 S / cm or more at room temperature. In addition, the short ethylene oxide chain unit is difficult to efficiently chelate lithium ions and accordingly the limit of the ionic conductivity is appearing.

Republic of Korea Patent No. 10-1527560 (2015.06.03), "Polymer electrolyte for lithium secondary battery, a method of manufacturing the same, and a lithium secondary battery comprising the same" Republic of Korea Patent No. 10-0531724 (Nov. 22, 2005), "Oligomer viscous impregnated porous membrane type solventless polymer electrolyte and secondary battery employing the same"

Accordingly, the present inventors have conducted various studies to solve the above problems, and when the polycarbonate-based linear polymer is prepared by introducing polyethylene oxide having a molecular weight of a specific value or more, and blended with polyethylene oxide to prepare a solid electrolyte, the electrolyte The present invention was completed by confirming that the ion conductivity of the present invention can be improved to ensure a suitable processability capable of forming a flexible film capable of free standing at room temperature.

Accordingly, an object of the present invention is to provide a solid electrolyte composition for a secondary battery including a polyethylene oxide-containing polycarbonate-based linear polymer and a polyethylene oxide polymer.

In addition, another object of the present invention to provide a solid electrolyte for a secondary battery formed by crosslinking the composition.

In order to achieve the above object, the present invention,

To provide a solid electrolyte composition for a secondary battery comprising a polycarbonate-based polymer and a polyethylene oxide comprising a structure of the formula (1).

[Formula 1]

(N and m are each independently an integer of 8≤n≤114 and 2≤m≤500, and R ₁ and R ₂ are each independently hydrogen or independently of the substituted or unsubstituted C1 to C6 Alkyl group)

One embodiment of the present invention is that the weight average molecular weight of the polycarbonate-based polymer is 1,000 to 200,000 g / mol.

One embodiment of the present invention is that the number average molecular weight of the polyethylene oxide is 20,000 to 2,000,000.

One embodiment of the present invention is that the polycarbonate-based polymer and polyethylene oxide is a weight ratio of 1:99 to 50:50.

One embodiment of the invention is that the composition further comprises a crosslinking agent.

In one embodiment of the present invention, the crosslinking agent is any one selected from the group consisting of an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and a vinyl-based crosslinking agent.

One embodiment of the present invention is that the crosslinking agent is included in 0.1 to 20 parts by weight relative to 100 parts by weight of the total electrolyte composition.

In addition, the present invention,

It provides a secondary battery solid electrolyte formed by heat or photocuring the above-mentioned solid electrolyte composition for secondary batteries.

One embodiment of the present invention is to include 10 to 90 parts by weight of the lithium salt in 100 parts by weight of the electrolyte composition.

One embodiment of the present invention the lithium salt is LiF, LiCl, LiBr, LiI, LiClO ₄ , LiClO ₃ , LiAsF ₆ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiNO ₃ , LiN (CN) ₂ , LiPF ₆ , Li (CF ₃ ) ₂ PF ₄ , Li (CF ₃ ) ₃ PF ₃ , Li (CF ₃ ) ₄ PF ₂ , Li (CF ₃ ) ₅ PF, Li (CF ₃ ) ₆ P, LiSO ₃ CF ₃ , LiSO ₃ C _{4 F 9, LiSO 3 (CF} 2) 7 CF 3, LiN (SO 2 CF 3) 2, LiOC (CF 3) 2 CF 2 CF 3, LiCO 2 CF 3, LiCO 2 CH 3, LiSCN, LiB (C 2 O ₄ ) ₂ , LiBF ₂ (C ₂ O ₄ ) and one or more selected from the group consisting of LiBF ₄ .

One embodiment of the present invention is that the thickness of the electrolyte is 10 to 1000㎛.

The solid electrolyte composition for a secondary battery according to the present invention may include a polyethylene oxide-containing polycarbonate-based linear polymer and a plasticized polyethylene oxide-based polymer to improve ion conductivity and electrochemical stability of an electrolyte of a lithium secondary battery. It is possible to secure a suitable processability capable of forming a flexible film capable of standing free.

Hereinafter, the present invention will be described in more detail.

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.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present invention, the term 'comprise' or 'having' is used to designate that there exists a feature, a number, a step, an operation, a component, a part, or a combination thereof described in the specification, and one or more other It is to be understood that the present invention does not exclude the possibility of adding or presenting features or numbers, steps, operations, components, components, or combinations thereof.

The present invention relates to a solid electrolyte composition for a secondary battery and a solid electrolyte prepared therefrom, and to an electrolyte composition blended with polycarbonate and polyethylene oxide having improved ionic conductivity and free standing properties at room temperature, and a solid electrolyte using the same. .

Solid Electrolyte Composition for Secondary Battery

The present invention provides a linear polymer in which a polyethylene oxide unit is present between carbonate groups as a structure capable of suppressing crystallinity of the polyethylene oxide polymer to improve lithium ion conductivity and simultaneously obtaining high ion dissociation and voltage stability of the carbonate group. do. In addition, the present invention provides an electrolyte composition in which polyethylene oxide having a molecular weight of more than a predetermined value is blended with a polymer that can form a flexible film while standing freely and exhibit an additional plasticizing effect.

Polycarbonate-based linear polymer in which polyethylene oxide is introduced according to an embodiment of the present invention may be a compound represented by the following formula (1).

 [Formula 1]

In Formula 1, n and m are each independently an integer of 8≤n≤114 and 2≤m≤500, and R ₁ and R ₂ are n and m are each independently hydrogen or independently substituted or unsubstituted C1 To C6 is an alkyl group.

The polymer of Formula 1 may have a weight average molecular weight of 1,000 to 200,000 g / mol.

In Formula 1, n is the added mole number of ethylene oxide, and if n is less than 8, effective chelating of lithium salt is difficult, and thus ionic conductivity is poor, and when n is more than 114, the polymerization reactivity of polyethylene oxide is significantly lowered, resulting in poly It may be difficult to prepare a carbonate-based polymer. In Chemical Formula 1, m may be a molecular weight determined by a combination of n and m as the number of addition moles of carbonate. If the weight average molecular weight of the formula (1) is less than 1,000 g / mol, the solid electrolyte membrane is too plasticized to be sticky or unsuitable for handling, if it is more than 200,000 g / mol does not sufficiently plasticize the polyethylene oxide may be insufficient to improve the ionic conductivity It adjusts suitably within the said range.

The polycarbonate-based linear polymer in which the polyethylene oxide of Formula 1 is introduced may be prepared through condensation polymerization of polyethylene oxide and dialkyl carbonate. The dialkyl carbonate may have an alkyl group of C1 to C6, diethyl carbonate (DEC), dimethyl carbonate (dimethyl carbonate, DMC), dipropyl carbonate (dipropyl carbonate, DPC) and the like, but is not limited thereto.

The condensation polymerization reaction is preferably carried out under catalytic conditions. The catalysts include inorganic catalysts such as NaH, K ₂ CO ₃ , NaO t -Bu, KtO t -Bu, dimethylaminopyridine (DMAP), 1,8-Diazabicyclo [5.4.0] undec-7-ene (DBU), triethylamine Organic catalysts such as (TEA), 1,3-bis [3,5-bis (trifluoromethyl) phenyl] thiourea may be used, but are not limited thereto.

The condensation reaction can be promoted by the effective removal of alkanol generated as a by-product, for this purpose it can be heated under vacuum to proceed with the reaction. The heating may proceed at 50 to 250 ° C, preferably at 70 to 200 ° C, but is not limited thereto.

The molar ratio of polyethylene oxide: dialkylcarbonate according to the present invention may be selected from a ratio of 2: 1 to 1: 2, but is not limited thereto.

In one embodiment of the present invention, the mixing ratio of the linear polycarbonate-based polymer of Formula 1 and polyethylene oxide may be 1:99 to 50:50. When mixed in the above range, the solid electrolyte membrane exhibits sufficient mechanical strength, thereby facilitating handling and ensuring high ion conductivity with a sufficient plasticizing effect.

In one embodiment of the present invention, the polyethylene oxide is preferably selected from the range of 20,000 to 2,000,000 number average molecular weight. If the number average molecular weight of polyethylene oxide is 20,000 or less, there is a high probability of dewetting of the film during the curing or drying process, and if it is 2,000,000 or more, the compatibility with the polycarbonate linear polymer is sharply lowered to form a homogeneous blend film. It can be difficult.

In one embodiment of the present invention, the solid electrolyte composition for a secondary battery including the linear polycarbonate-based polymer of Formula 1 and polyethylene oxide may further include a crosslinking agent for improving mechanical strength or manufacturing processability of the solid electrolyte membrane. The crosslinking agent allows the electrolyte membrane to crosslink through a heat drying process or an additional exposure process of the electrolyte membrane, thereby improving mechanical strength and maintaining the shape of the film.

 The kind of the crosslinking agent is not particularly limited, and any one selected from the group consisting of an isocyanate crosslinking agent, an epoxy crosslinking agent, a thermal polymerization crosslinking agent such as an aziridine crosslinking agent and a photopolymerization crosslinking agent such as a vinyl-based crosslinking agent can be used. The content of the crosslinking agent may be 0.01 to 20 parts by weight based on 100 parts by weight of the total polycarbonate-based polymer of Formula 1 and the polymer exhibiting the plasticizing effect, but is not limited thereto. If the content of the crosslinking agent is less than 0.01 part by weight, curing may not be sufficiently performed, and thus, the improvement of mechanical strength may be insufficient. If the content of the crosslinking agent is more than 20 parts by weight, the solid electrolyte membrane may be too hard, resulting in insufficient interfacial adhesion with the electrode, resulting in increased interfacial resistance or lithium. Ionic conductivity can be significantly lowered, so adjust appropriately within this range.

Specific examples of the isocyanate crosslinking agent include diisocyanate compounds such as toluene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoborone diisocyanate, tetramethylxylene diisocyanate or naphthalene diisocyanate, or the diisocyanate. A compound obtained by reacting a compound with a polyol can be used. As the polyol, for example, trimethylol propane can be used.

Specific examples of the epoxy crosslinking agent include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N, N, N ', N'-tetraglycidyl ethylenediamine and glycerin diglycid. And one or more selected from the group consisting of dil ethers, and specific examples of aziridine crosslinking agents include N, N'-toluene-2,4-bis (1-aziridinecarboxamide), N, N'-diphenyl Consisting of methane-4,4'-bis (1-aziridinecarboxamide), triethylene melamine, bisisoprotaloyl-1- (2-methylaziridine) and tri-1-aziridinylphosphine oxide One or more selected from the group, but is not limited thereto.

Specific examples of the vinyl-based crosslinking agent include ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, tri (propylene glycol) di (meth) acrylate, and tris (2- (meth) acryl. Ethyl) isocyanurate, trimethylolpropane tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol di (meth) ) Acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like. But it is not limited thereto.

The vinyl-based crosslinking agent forms a crosslinked structure upon UV irradiation together with the photopolymerization initiator to improve the physical strength of the film and to form the solid electrolyte membrane according to the present invention as a free standing film. Examples of the photopolymerization initiator may be a compound selected from the group consisting of acetophenone compounds, biimidazole compounds, triazine compounds, and oxime compounds.

Acetophenone compounds which can be used as the photopolymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one and 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane- 1-one, 4- (2-hydroxyethoxy) -phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexylphenylketone, benzoinmethyl ether, benzoinethyl ether, benzoin Isobutyl ether, benzoin butyl ether, 2,2-dimethoxy-2-phenylacetophenone, 2-methyl- (4-methylthio) phenyl-2-morpholino-1-propan-1-one, 2- Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2- (4-bromo-benzyl-2-dimethylamino-1- (4-morpholinophenyl)- Butan-1-one and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one, and the non-imidazole compound is 2,2- Bis (2-chlorophenyl) -4,4 ', 5,5'-tetraphenyl biimidazole, 2,2'-bis (o-chlorophenyl) -4,4', 5,5'-tetrakis ( 3,4,5-trimethoxy Nil) -1,2'-biimidazole, 2,2'-bis (2,3-dichlorophenyl) -4,4 ', 5,5'-tetraphenyl biimidazole, and 2,2'-bis (o-chlorophenyl) -4,4,5,5'-tetraphenyl-1,2'-biimidazole, selected from the group consisting of triazine compounds, and 3- {4- [2,4-bis (Trichloromethyl) -s-triazin-6-yl] phenylthio} propionic acid, 1,1,1,3,3,3-hexafluoroisopropyl-3- {4- [2,4- Bis (trichloromethyl) -s-triazin-6-yl] phenylthio} propionate, ethyl-2- {4- [2,4-bis (trichloromethyl) -s-triazin-6-yl ] Phenylthio} acetate, 2-epoxyethyl-2- {4- [2,4-bis (trichloromethyl) -s-triazin-6-yl] phenylthio} acetate, cyclohexyl-2- {4- [2,4-bis (trichloromethyl) -s-triazin-6-yl] phenylthio} acetate, benzyl-2- {4- [2,4-bis (trichloromethyl) -s-triazine- 6-yl] phenylthio} acetate, 3- {chloro-4- [2,4-bis (trichloromethyl) -s-triazin-6-yl] phenyl Thio} propionic acid, 3- {4- [2,4-bis (trichloromethyl) -s-triazin-6-yl] phenylthio} propionamide, 2,4-bis (trichloromethyl) -6 -p-methoxystyryl-s-triazine, 2,4-bis (trichloromethyl) -6- (1-p-dimethylaminophenyl) -1,3, -butadienyl-s-triazine, And 2-trichloromethyl-4-amino-6-p-methoxystyryl-s-triazine, and the oxime compound is 1,2-octadione-1- (4-phenylthio ) Phenyl-2- (o-benzoyloxime) (CGI 124 from Ciba-Geigy Co., Ltd.), and ethanone-1- (9-ethyl) -6- (2-methylbenzoyl-3-yl) -1- ( o-acetyl oxime) (CGI 242, Ciba-Geigi), oxime OX-03 (Ciba-Geigi), NCI-831 (Adeka), PI-102 (LG Chem), PBG 304, PBG 305 , PBG 3057 (Trony).

The content of the photopolymerization initiator may be 0.01 to 5 parts by weight, or 0.1 to 1 part by weight based on the total weight of the polymer and the vinyl-based crosslinking agent, but is not limited thereto.

Manufacturing Method of Solid Electrolyte for Secondary Battery

The present invention provides a solid electrolyte for a secondary battery formed using the solid electrolyte composition for a secondary battery described above. The solid electrolyte may exhibit the effects described above.

The secondary battery solid electrolyte may be prepared by using the electrolyte composition including the above-described crosslinking agent and lithium salt in a blend of a polycarbonate-based polymer including the structure of Chemical Formula 1 and a polymer including polyethylene oxide. In one embodiment of the present invention, the solid electrolyte may include 10 to 90 parts by weight of a lithium salt in 100 parts by weight of the electrolyte composition.

In one embodiment of the present invention, the electrolyte is LiF, LiCl, LiBr, LiI, LiClO ₄ , LiClO ₃ , LiAsF ₆ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiNO ₃ , LiN (CN) ₂ , LiPF ₆ , Li (CF ₃ ) ₂ PF ₄ , Li (CF ₃ ) ₃ PF ₃ , Li (CF ₃ ) ₄ PF ₂ , Li (CF ₃ ) ₅ PF, Li (CF ₃ ) ₆ P, LiSO ₃ CF ₃ , LiSO ₃ C _{4 F 9, LiSO 3 (CF} 2) 7 CF 3, LiN (SO 2 CF 3) 2, LiOC (CF 3) 2 CF 2 CF 3, LiCO 2 CF 3, LiCO 2 CH 3, LiSCN, LiB (C 2 O ₄ ) ₂ , LiBF ₂ (C ₂ O ₄ ) and one or more lithium salts selected from the group consisting of LiBF ₄ .

The solid electrolyte according to the present invention may be formed by heat or photocuring the above-described solid electrolyte composition. To this end, the electrolyte composition may include the step of dissolving in a solvent for 1 to 6 hours. The solvent may be used in various solvents known in the art in consideration of the desired performance, for example, N-methylpyrrolidone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl Carbonate, diethyl carbonate, gamma-butylo lactone, 1,2-dimethoxy ethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylsulfoxide, formamide, dimethylformamide, acetonitrile, nitro Methane, methyl formate, methyl acetate, triester phosphate, trimethoxy methane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, propionic acid An organic solvent such as methyl or ethyl propionate may be used, but is not limited thereto.

Thereafter, the solution may be cast on a release-treated PET film or a Teflon plate and then thermoset or UV exposure may be performed. The coated film may be prepared by drying at 50 ° C. and 150 ° C. under normal pressure, and then drying the film at a pressure of 50 ° C. to 150 ° C., and then vacuuming it under vacuum to 2%. Separation of the completely dried solid electrolyte film from the support can produce a free standing membrane with lithium ion conductivity.

According to one embodiment of the present invention, the thickness of the solid electrolyte may be 10 to 1000 ㎛, preferably 50 to 250 ㎛. If the thickness of the electrolyte is less than the above range, the mechanical properties of the solid electrolyte may be lowered, and if it exceeds the above range, it may be difficult to reduce the electric short and the cross over of the electrolyte material. It adjusts suitably in the said range so that a lithium ion conductivity characteristic can be exhibited.

Hereinafter, the present invention will be described in more detail with reference to examples and the like, but the scope and contents of the present invention are not limited or interpreted by the following examples. In addition, if it is based on the disclosure of the present invention including the following examples, it will be apparent that those skilled in the art can easily carry out the present invention, the results of which are not specifically presented experimental results, these modifications and modifications are attached to the patent It goes without saying that it belongs to the claims.

Example

Polymer according to an embodiment of the present invention was measured the molecular weight under the following conditions.

The number average molecular weight (Mn) and molecular weight distribution (PDI) were measured using gel permeation chromatography (GPC) under the following conditions, and in the preparation of calibration curves, the measurement results were converted using standard polystyrene from Agilent. It was.

<Measurement conditions>

Meter: Waters GPC (Alliance 4)

Column: Connect 2 PL Mixed B

Column temperature: 65 ℃

Eluent: DMF / 0.05M LiBr

Flow rate: 1.0 mL / min

Concentration: ~ 1 mg / mL (100 μl injection)

Production Example 1. Polyethylene Oxide  Containing linear polycarbonate-based polymer (A1)

In a 250 ml Two-neck flask, 30 g of polyethylene oxide (Mn: 1000) previously removed from water, 4.1 g of dimethyl carbonate, and 0.04 g of dimethylaminopyridine (DMAP) were added as a catalyst. A mechanical stirrer and a distillation apparatus were installed and refluxed at 130 ° C. for 3 hours. Thereafter, the temperature was raised to 170 ° C. and condensation polymerization was performed for 18 hours while removing unreacted dimethyl carbonate and methanol under vacuum. The reaction was precipitated and purified in diethyl ether to obtain Polymer A1 of Preparation Example 1 (Mw 32,000, Mw / Mn 1.56).

Production Example 2. Polyethylene Oxide  Containing linear polycarbonate-based polymer (A2)

In a 250 ml two-neck flask, 40 g of polyethylene oxide (Mn: 2000) previously removed from water, 2.7 g of dimethyl carbonate, and 0.01 g of NaH were added as a catalyst. A mechanical stirrer and a distillation apparatus were installed and refluxed at 130 ° C. for 3 hours. Thereafter, the temperature was raised to 170 ° C. and condensation polymerization was performed for 18 hours while removing unreacted dimethyl carbonate and methanol under vacuum. The reaction was precipitated and purified in diethyl ether to obtain Polymer A2 of Preparation Example 2 (Mw 49,000, Mw / Mn 1.50).

Production Example  3. Polyethylene Oxide  Containing linear polycarbonate-based polymer (A3)

In a 250 ml two-neck flask, 40 g of polyethylene oxide (Mn: 2000) previously removed from water, 2.2 g of dimethyl carbonate, and 0.01 g of NaH were added as a catalyst. A mechanical stirrer and a distillation apparatus were installed and refluxed at 130 ° C. for 3 hours. Thereafter, the temperature was raised to 170 ° C. and condensation polymerization was performed for 42 hours while removing unreacted dimethyl carbonate and methanol under vacuum. The reaction was precipitated and purified in diethyl ether to obtain polymer A3 of Preparation Example 3 (Mw 85,000, Mw / Mn 1.57).

compare Production Example  One. Diethylene glycol  Containing linear polycarbonate-based polymer (B1)

In a 50 ml Schlenk flask, 10 g of polyethylene oxide (Mn: 400) previously removed from water, 3.4 g of dimethyl carbonate, and 0.03 g of dimethylaminopyridine (DMAP) were added as a catalyst. After putting a stiring bar (stirring bar), a detiling apparatus was installed and refluxed at 130 ° C. for 3 hours. Thereafter, the detilation apparatus was removed, the temperature was raised to 170 ° C., and condensation polymerization was performed for 18 hours while removing unreacted dimethyl carbonate and methanol under vacuum. The reaction product was precipitated and purified in diethyl ether to obtain the polymer B1 of Comparative Preparation Example 1 (Mn, _NMR 3100)

compare Production Example  2. Aliphatic  Chain-containing linear polycarbonate polymer (B2)

Into a 50 ml Schlenk flask, 10 g of 1,12-dodecanediol, which had been previously dehydrated, 10 g of dimethyl carbonate, and 0.06 g of 4-dimethylaminopyridine (DMAP) were added as a catalyst. It was. After putting a stiring bar (stirring bar), a detiling apparatus was installed and refluxed at 130 ° C. for 3 hours. Thereafter, the detilation apparatus was removed, the temperature was raised to 170 ° C., and condensation polymerization was performed for 18 hours while removing unreacted dimethyl carbonate and methanol under vacuum. The reaction product was precipitated and purified in diethyl ether to obtain polymer B2 of Comparative Preparation Example 2 (Mw 20,000, Mw / Mn 1.55).

Example . Preparation of Solid Electrolyte

Preparation of the solid electrolyte was carried out in a dry room. The content of lithium bis (trifluoromethanesulfonyl) imide (LiN (SO ₂ CF ₃ ) ₂ , LiTFSI) as the polymer prepared in Preparation Examples 1 and 2 and the polymer having the plasticizing effect, polyethylene oxide and lithium salt As shown in Table 1 below, the solution dissolved in anhydrous tetrahydrofuran (hereinafter THF) solvent was stirred for 6 hours to prepare a uniform solution.

The solution was doctor blade coated on a release-treated PET film with an appropriate gap, dried at 60 ° C. for 4 hours, and then heated by drying at 80 ° C. for an additional 2 hours. Thereafter, the solid film was removed from the PET film to obtain a freestanding solid electrolyte for secondary batteries having a thickness of 50 to 200 µm.

Comparative example . Preparation of Solid Electrolyte

The solution prepared in Comparative Preparation Examples 1 and 2 alone or blended with polyethylene oxide which is a polymer having a plasticizing effect and the LiTFSI content with a lithium salt was dissolved in anhydrous THF solvent for 6 hours by varying the LiTFSI content as shown in Table 1 below. To prepare a uniform solution.

After the doctor blade coated the appropriate solution to the release-treated PET film in a suitable gap, and dried for 4 hours at 60 ℃, and then dried by heating at 90 ℃ temperature for an additional 2 hours. Thereafter, the solid film was removed from the PET film, and the state of the film was examined to determine the ionic conductivity as in the following experimental example when a freestanding film was formed.

Examples 1 to 6 and Comparative Examples 1 to 5 according to the above Examples and Comparative Examples are shown in Table 1 below.

Polymer (wt%) Polyethylene oxide Mn (wt%) LiTFSI Content
(wt%) Example 1 A1 (10) PEO 100,000 (50) 40 Example 2 A1 (20) PEO 100,000 (40) 40 Example 3 A2 (10) PEO 100,000 (50) 40 Example 4 A2 (20) PEO 100,000 (40) 40 Example 5 A3 (10) PEO 100,000 (50) 40 Example 6 A3 (20) PEO 100,000 (40) 40 Comparative Example 1 - PEO 100,000 (60) 40 Comparative Example 2 B1 (10) PEO 100,000 (50) 40 Comparative Example 3 B1 (20) PEO 100,000 (40) 40 Comparative Example 4 B2 (10) PEO 100,000 (50) 40 Comparative Example 5 B2 (20) PEO 100,000 (40) 40

Experimental Example . Ionic Conductivity Measurement of Solid Electrolyte

The ionic conductivity of the solid electrolytes prepared in Examples 1 to 6 and Comparative Examples 1 to 5 was measured using the following Equation 1 after measuring the impedance thereof.

Film samples of the solid electrolyte having a constant width and thickness were prepared for the measurement. After contacting a sus substrate having excellent electronic conductivity with an ion blocking electrode on both sides of the plate-shaped sample, an alternating voltage was applied through the electrodes on both sides of the sample. At this time, it set to the amplitude range of the measurement frequency of 0.1 Hz-10 MHz on the conditions applied. The bulk electrolyte resistance is obtained from the intersection (R _b ) where the semicircle or straight line of the measured impedance trajectory meets the real axis, and the ion conductivity of the polymer solid electrolyte membrane is calculated from the width and thickness of the sample and is shown in Table 2 below.

[Equation 1]

σ: ion conductivity

R _b : Impedance trajectory intersection with real axis

A: Width of the sample

t: thickness of sample

Ionic Conductivity (S / cm, 25 ° C) Membrane properties Example 1 3.2 x 10 ^-5 Flexible free standing membrane Example 2 4.7 x 10 ^-5 Flexible free standing membrane Example 3 4.8 x 10 ^-5 Flexible free standing membrane Example 4 7.5 x 10 ^-5 Flexible free standing membrane Example 5 1.3 x 10 ^-5 Flexible free standing membrane Example 6 3.6 x 10 ^-5 Flexible free standing membrane Comparative Example 1 8.7 x 10 ^-7 Breaking Free Standing Membrane Comparative Example 2 1.4 x 10 ^-6 Flexible free standing membrane Comparative Example 3 2.2 x 10 ^-6 Sticky waxy membrane Comparative Example 4 1.1 x 10 ^-6 Flexible free standing membrane Comparative Example 5 1.8 x 10 ^-6 Flexible free standing membrane

As shown in Table 2, when blended with a polycarbonate-based linear polymer and polyethylene oxide introduced polyethylene oxide was prepared a solid electrolyte, it can be seen that the membrane properties are excellent and the ionic conductivity is improved.

Claims (11)

A solid electrolyte composition for a secondary battery comprising a polycarbonate-based polymer and polyethylene oxide including the structure of Formula 1.
[Formula 1]

(N and m are each independently an integer of 8≤n≤114 and 2≤m≤500, and R ₁ and R ₂ are each independently hydrogen or independently of the substituted or unsubstituted C1 to C6 Alkyl group) The method of claim 1,
The polycarbonate-based polymer has a weight average molecular weight of 1,000 to 200,000 g / mol, a solid electrolyte composition for a secondary battery. The method of claim 1,
The polyethylene oxide has a number average molecular weight of 20,000 to 2,000,000 solid electrolyte composition for a secondary battery. The method of claim 1,
The polycarbonate-based polymer and polyethylene oxide is a solid electrolyte composition for a secondary battery, characterized in that the weight ratio of 1:99 to 50:50. The method of claim 1,
The composition is a solid electrolyte composition for a secondary battery, characterized in that it further comprises a crosslinking agent. The method of claim 5,
The crosslinking agent is any one selected from the group consisting of isocyanate crosslinking agent, epoxy crosslinking agent, aziridine crosslinking agent and vinyl-based crosslinking agent. The method of claim 5,
The crosslinking agent is a solid electrolyte composition for a secondary battery, characterized in that contained in 0.1 to 20 parts by weight relative to 100 parts by weight of the total electrolyte composition. The solid electrolyte for secondary batteries formed by heat or photocuring the solid electrolyte composition for secondary batteries of any one of Claims 1-7. The method of claim 8,
The electrolyte is a solid electrolyte for a secondary battery, characterized in that it comprises 10 to 90 parts by weight of lithium salt in 100 parts by weight of the electrolyte composition. The method of claim 9,
The lithium salt is LiF, LiCl, LiBr, LiI, LiClO ₄ , LiClO ₃ , LiAsF ₆ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiNO ₃ , LiN (CN) ₂ , LiPF ₆ , Li (CF ₃ ) ₂ PF ₄ , Li (CF ₃ ) ₃ PF ₃ , Li (CF ₃ ) ₄ PF ₂ , Li (CF ₃ ) ₅ PF, Li (CF ₃ ) ₆ P, LiSO ₃ CF ₃ , LiSO ₃ C ₄ F ₉ , LiSO ₃ ( _{CF 2) 7 CF 3, LiN} (SO 2 CF 3) 2, LiOC (CF 3) 2 CF 2 CF 3, LiCO 2 CF 3, LiCO 2 CH 3, LiSCN, LiB (C 2 O 4) 2, LiBF 2 (C ₂ O ₄ ) and a solid electrolyte for secondary batteries, characterized in that at least one selected from the group consisting of LiBF ₄ . The method of claim 8,
Solid electrolyte for a secondary battery, characterized in that the thickness of the electrolyte is 10 to 1000㎛.