Composition for forming quasi-solid electrolyte and secondary battery

Abstract

The composition for forming a quasi-solid electrolyte according to the present invention comprises: a liquid electrolyte comprising a lithium salt and an organic solvent; a first monomer having an ionic functional group; a second monomer, the second monomer being different from the first monomer, and the second monomer having a crosslinkable functional group; and an initiator. The secondary battery according to the present invention comprises: a negative electrode; the positive electrode and the negative electrode are oppositely arranged; and an electrolyte layer, which is provided between the negative electrode and the positive electrode, and which contains a cured product of the quasi-solid electrolyte-forming composition. The positive electrode includes: a porous sulfur-containing matrix, the porous sulfur-containing matrix including a plurality of pores; and a cured product of the composition for forming a quasi-solid electrolyte, the cured product of the composition for forming a quasi-solid electrolyte being contained inside the plurality of pores.

Description

Technical Field

[0001] The present invention provides a composition for forming a quasi-solid electrolyte and a secondary battery. Background Technology

[0002] Rechargeable batteries are batteries that can be repeatedly charged and discharged. With the development of the information communication and display industries, rechargeable batteries are widely used as power sources for portable electronic communication devices such as portable cameras, mobile phones, and laptops (PCs). In addition, in recent years, battery packs that include rechargeable batteries have been developed for use as power sources in environmentally friendly vehicles such as hybrid electric vehicles.

[0003] Examples of secondary batteries include lithium secondary batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and lithium-sulfur batteries.

[0004] Currently, commercially available secondary batteries primarily use liquid electrolytes, which pose safety risks such as leakage, fire, and explosion due to rapid environmental changes including temperature fluctuations and external impacts. To address these issues, efforts are underway to solidify the electrolyte to ensure stability and increase energy density.

[0005] All-solid-state batteries can incorporate solid electrolytes such as gel polymers, oxides or sulfides, and composite polymers. Therefore, they can improve stability against fires and explosions caused by external impacts or changes in the external environment. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] One technical problem of the present invention is to provide a composition for forming a quasi-solid electrolyte that can provide a quasi-solid electrolyte with improved electrochemical and physical properties.

[0008] One technical problem of the present invention is to provide a secondary battery comprising a cured product of the quasi-solid electrolyte forming composition.

[0009] (II) Technical Solution

[0010] The quasi-solid electrolyte formation composition according to the present invention comprises: a liquid electrolyte comprising a lithium salt and an organic solvent; a first monomer having an ionic functional group; a second monomer different from the first monomer and having a crosslinking functional group; and an initiator.

[0011] In an exemplary embodiment, the first monomer may include: anionic functional groups; cationic functional groups; or anionic and cationic functional groups.

[0012] In an exemplary embodiment, the first monomer may include a nitrogen-based cationic functional group and a thio-based anionic functional group.

[0013] In an exemplary embodiment, the first monomer may comprise 3-(triallylammonium)propanesulfonate.

[0014] In an exemplary embodiment, the content of the first monomer may be from 0.1% to 5% by weight of the total weight of the quasi-solid electrolyte forming composition.

[0015] In an exemplary embodiment, the crosslinking functional group may include (meth)acrylate groups.

[0016] In an exemplary embodiment, the second monomer may comprise at least one selected from ethoxylated bisphenol A di(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, (meth)acrylate, carboxyethyl di(meth)acrylate, cyano(meth)acrylate, propylene glycol di(meth)acrylate, polyurethane di(meth)acrylate, neopentyl glycol di(meth)acrylate, isobornyl di(meth)acrylate, isophorone di(meth)acrylate, hexamethylene di(meth)acrylate, phenyl glycidyl ether di(meth)acrylate, and tetraethylene glycol di(meth)acrylate.

[0017] In an exemplary embodiment, the content of the second monomer may be from 5% to 20% by weight of the total weight of the quasi-solid electrolyte forming composition.

[0018] In an exemplary embodiment, the weight ratio of the second monomer to the first monomer in the total weight of the quasi-solid electrolyte forming composition may be from 1 to 10.

[0019] In an exemplary embodiment, the initiator may comprise a thermal initiator or a photoinitiator.

[0020] In an exemplary embodiment, the initiator content may be from 0.1 parts by weight to 10 parts by weight relative to the total weight of 100 parts by weight of the first monomer and the second monomer.

[0021] In an exemplary embodiment, the lithium salt may comprise a first lithium salt containing an organic anion and a second lithium salt containing an inorganic anion.

[0022] In an exemplary embodiment, the organic solvent may comprise cyclic ether solvents and linear ether solvents.

[0023] The secondary battery according to the present invention comprises: a negative electrode; a positive electrode disposed opposite to the negative electrode; and an electrolyte layer disposed between the negative electrode and the positive electrode, the electrolyte layer comprising a cured product of a quasi-solid electrolyte forming composition. The positive electrode comprises: a porous sulfur-containing matrix comprising a plurality of pores; and a cured product of the quasi-solid electrolyte forming composition contained within the plurality of pores. The quasi-solid electrolyte forming composition comprises: a liquid electrolyte comprising a lithium salt and an organic solvent; a first monomer having ionic functional groups; a second monomer different from the first monomer and having crosslinking functional groups; and an initiator.

[0024] In an exemplary embodiment, the cured product of the quasi-solid electrolyte forming composition may comprise a copolymer of the first monomer and the second monomer.

[0025] (III) Beneficial Effects

[0026] The cured composition for forming a quasi-solid electrolyte according to an exemplary embodiment of the present invention may contain a copolymer having ionic functional groups. Byproducts (e.g., lithium polysulfides) that may form during repeated charge-discharge cycles in a battery including the cured composition can be captured by the ionic functional groups. Therefore, the battery life characteristics can be improved.

[0027] A secondary battery according to an exemplary embodiment of the present invention may include an electrolyte layer and electrodes having improved ionic conductivity and stability. Therefore, the battery's lifespan characteristics can be improved. Attached Figure Description

[0028] Figure 1 This is a schematic diagram showing a cross-section of a secondary battery according to an exemplary embodiment.

[0029] Figure 2 The graph shows the capacity and coulombic efficiency of the batteries of Example 1, Comparative Example 1 and Comparative Example 2 according to the cycle.

[0030] Explanation of reference numerals in the attached figures:

[0031] 100: Negative electrode; 200: Positive electrode

[0032] 205: Porous sulfur-containing matrix; 210: Multiple pores

[0033] 300: Electrolyte layer Detailed Implementation

[0034] According to the present invention, a quasi-solid electrolyte forming composition comprising a liquid electrolyte, an ionic monomer, and a crosslinking monomer is provided. According to the present invention, a secondary battery comprising a cured product of the said composition is provided.

[0035] The present invention will now be described in detail. However, this is merely an exemplary description, and the present invention is not limited to the specific embodiments described herein.

[0036] A quasi-solid electrolyte forming composition (hereinafter, simply referred to as the composition) according to an exemplary embodiment comprises a first monomer. The first monomer has ionic functional groups. Therefore, an electrolyte layer with high ionic conductivity can be achieved. Furthermore, the ionic functional groups of the first monomer can capture lithium polysulfides, byproducts formed during the charging and discharging of lithium-sulfur batteries, thereby improving the battery's lifespan characteristics.

[0037] In exemplary embodiments, the first monomer may comprise: anionic functional groups; cationic functional groups; or both anionic and cationic functional groups. In some embodiments, the first monomer may comprise both anionic and cationic functional groups simultaneously, for example, it may comprise a zwitter compound.

[0038] The anionic functional group can be, for example, sulfonate, sulfinate, carbonate, carboxylate, phosphate, alkoxide anion, thioalkoxide anion, cyanide anion, nitrite, etc.

[0039] The cationic functional group can be, for example, primary ammonium (RNH3). + ), secondary ammonium (R2NH2) + ), tertiary ammonium (R3NH + ), Quaternary ammonium (R4N) + ), α-mono ...

[0040] In an exemplary embodiment, the first monomer may contain at least one ionic functional group. When the first monomer contains multiple ionic functional groups, each of the multiple ionic functional groups may be anionic or cationic functional groups independently.

[0041] In an exemplary embodiment, the first monomer may comprise a nitrogen-based cationic functional group and a thio-based anionic functional group. For example, the nitrogen-based cationic functional group may comprise primary ammonium (RNH3). + ), secondary ammonium (R2NH2) + ), tertiary ammonium (R3NH + ), Quaternary ammonium (R4N)+ (e.g., imidazolium, etc.), wherein the thioanionic functional group may include sulfonate, sulfinate, thioalkoxide, etc.

[0042] The first monomer may further include crosslinking functional groups different from the ionic functional groups. These crosslinking functional groups may polymerize with the crosslinking functional groups of the second monomer described below to form a copolymer.

[0043] The crosslinking functional group may include, for example, carbon-carbon double bonds, (meth)acrylate groups, etc.

[0044] In an exemplary embodiment, the first monomer may contain the counterion of the ionic functional group. For example, when the first monomer contains a cationic functional group, it may contain Br. - Cl - I - (CF3SO2)2N - (FSO2)2N - CF3SO3 - For example, when the first monomer contains anionic functional groups, it may contain cations such as metal salts.

[0045] In an exemplary embodiment, the first monomer may be represented by the following chemical formula 1.

[0046] [Chemical Formula 1]

[0047]

[0048] In chemical formula 1, L can be an alkylene group having 1 to 5 carbon atoms, and R1 to R3 can each be an alkenyl group having 2 to 5 carbon atoms. s It can be a thio-anionic functional group.

[0049] In an exemplary embodiment, the first monomer may comprise 3-(triallylamyl)propanesulfonate, represented by the following chemical formula 2.

[0050] [Chemical Formula 2]

[0051]

[0052] In an exemplary embodiment, the content of the first monomer may be from 0.1% to 5% by weight of the total weight of the composition.

[0053] In some embodiments, the content of the first monomer may be from 0.5% to 4.5% by weight or from 2% to 4% by weight of the total weight of the composition.

[0054] Within the aforementioned range, the cured form of the composition can have further improved ionic conductivity, and the battery comprising the cured form of the composition can maintain high capacity even during repeated charge and discharge cycles.

[0055] A quasi-solid electrolyte forming composition according to an exemplary embodiment comprises a second monomer, which is different from the first monomer and has crosslinking functional groups. The second monomer can be polymerized with the first monomer to form a copolymer.

[0056] The second monomer may not contain ionic functional groups. Therefore, it is possible to prevent the copolymer of the first and second monomers from exhibiting excessive ionicity, which could lead to a decrease in the ionic conductivity of the electrolyte layer.

[0057] In an exemplary embodiment, the second monomer may contain at least one crosslinking functional group. In some embodiments, the second monomer may contain more than two crosslinking functional groups. The second monomer may be a multifunctional monomer containing two to six crosslinking functional groups. When the second monomer contains more than two crosslinking functional groups, the multiple crosslinking functional groups may be the same as or different from each other.

[0058] In an exemplary embodiment, the crosslinking functional group may be the same as the crosslinking functional group described in the first monomer. For example, the crosslinking functional group may be a (meth)acrylate group.

[0059] In exemplary embodiments, the second monomer may comprise ethoxylated bisphenol A di(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, (meth)acrylate, carboxyethyl di(meth)acrylate, cyano(meth)acrylate, propylene glycol di(meth)acrylate, polyurethane di(meth)acrylate, neopentyl glycol di(meth)acrylate, isobornyl di(meth)acrylate, isophorone di(meth)acrylate, hexamethylene di(meth)acrylate, phenyl glycidyl ether di(meth)acrylate, and tetraethylene glycol di(meth)acrylate, etc. For example, the second monomer may comprise ethoxylated trimethylolpropane triacrylate. These may be used alone or in combination of two or more.

[0060] In an exemplary embodiment, the content of the second monomer can be from 5% to 20% by weight of the total weight of the composition. In some embodiments, the content of the second monomer can be from 7% to 15% by weight or from 9% to 12% by weight of the total weight of the composition. Within the above ranges, the durability of the electrolyte layer of the cured product containing the composition can be improved.

[0061] In an exemplary embodiment, the weight ratio of the second monomer to the first monomer in the total weight of the composition can be from 1 to 10. In some embodiments, the weight ratio of the second monomer to the first monomer in the total weight of the composition can be from 2 to 7 or from 3 to 4. Within the above ranges, the ion content per unit of the copolymer of the first and second monomers is appropriate, thus improving the battery life characteristics while enhancing the ionic conductivity of the electrolyte layer.

[0062] The quasi-solid electrolyte formation composition according to an exemplary embodiment comprises a liquid electrolyte. The liquid electrolyte comprises a lithium salt and an organic solvent, and can serve as a dispersion medium for the first monomer and the second monomer.

[0063] In an exemplary embodiment, the lithium salt may comprise more than one lithium salt compound. For example, the lithium salt may be composed of Li + X - This indicates that the anion (X) of the lithium salt is... - Non-restrictive examples of PF6 can be listed. - F - Cl - ,Br - I - NO3 - N(CN)2 - ClO4 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - CF3CF2SO3 - (CF3SO2)2N - (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2)2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - (CF3CF2SO2)2N - BF4 - B(C2O4)2 - BF2(C2O4)- B(C3H2O4)2 - BF2(C3H2O4) - B(C3HO4F)2 - B(C3F2O4)2 - The aforementioned anions can be used alone in lithium salts or in combinations of two or more.

[0064] In an exemplary embodiment, the lithium salt may comprise a first lithium salt containing an organic anion and a second lithium salt containing an inorganic anion. The organic anion may be a carbon-containing anion, and the inorganic anion may be a carbon-free anion. When the lithium salt comprises different types of lithium salt compounds containing different anions, the stability of the electrolyte layer of the cured product containing the composition can be improved.

[0065] For example, the first lithium salt may be (CF3SO2)2N. - Lithium bis(trifluoromethanesulfonyl)imide, wherein the second lithium salt may contain NO3. - Lithium nitrate.

[0066] In an exemplary embodiment, the lithium salt may be contained in the organic solvent at a concentration of 0.01M to 5M, 0.01M to 4M, 0.5M to 3M, or 0.5M to 2M. Within the above concentration ranges, the movement of lithium ions and / or electrons is smooth during the charging and discharging of the lithium secondary battery, thereby increasing capacity and charging / discharging efficiency.

[0067] In an exemplary embodiment, the contents of the first lithium salt and the second lithium salt can each be independently 0.01M to 0.5M relative to the organic solvent. In some embodiments, the content of the second lithium salt can be greater than the content of the first lithium salt.

[0068] In an exemplary embodiment, the organic solvent may comprise a cyclic ether solvent and a linear ether solvent. Both the cyclic ether solvent and the linear ether solvent may independently contain at least one ether group. For example, the cyclic ether solvent and the linear ether solvent may contain more than two ether groups.

[0069] For example, the cyclic ether solvent may contain 1,3-dioxolane, 2-methyltetrahydrofuran, tetrahydrofuran, etc.

[0070] For example, the straight-chain ether solvent may include 1,2-dimethoxyethane, dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, etc.

[0071] These can be used individually or in combination of two or more.

[0072] According to an exemplary embodiment, the volume ratio of the linear ether solvent to the cyclic ether solvent in the total volume of the organic solvent can be from 0.1 to 10. According to some embodiments, the volume ratio of the linear ether solvent to the cyclic ether solvent in the total volume of the organic solvent can be from 0.5 to 3.

[0073] According to an exemplary embodiment, the organic solvent may further comprise carbonate-based solvents, ester-based solvents, ketone-based solvents, alcohol-based solvents, and aprotic solvents, etc. These can be used alone or in combination of two or more.

[0074] For example, the carbonate-based solvent may include propylene carbonate, ethylene carbonate, butene carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, diethyl carbonate, dipropyl carbonate, etc.

[0075] The ester-based solvent contains an ester group rather than a carbonate group, and is different from carbonate-based solvents. For example, the ester-based solvent may include methyl acetate, ethyl acetate, n-propyl acetate, ethyl 1,1-dimethylacetate, methyl propionate, ethyl propionate, γ-butyrolactone, decanolactone, valproic acid lactone, mevalonolactone, caprolactone, etc.

[0076] Examples of ketone solvents include cyclohexanone. Examples of alcohol solvents include ethanol and isopropanol.

[0077] The aprotic solvent may include nitrile solvents, amide solvents (such as dimethylformamide), sulfolane solvents, etc.

[0078] A quasi-solid electrolyte forming composition according to an exemplary embodiment includes an initiator. When energy is applied to the composition, the initiator can initiate a polymerization reaction between the first monomer and the second monomer.

[0079] In an exemplary embodiment, the initiator may comprise a thermal initiator or a photoinitiator.

[0080] For example, the thermal initiator may comprise: benzoyl peroxide, dibenzoyl peroxide, succinic acid peroxide, dilauroyl peroxide, didecyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, di-tert-pentyl peroxide, α,α'-di(tert-butylperoxy)dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne, tert-butyl peroxide, α-cumyl peroxynedecanoate, α-cumyl peroxyneheptanoate, tert-pentyl peroxynedecanoate, tert-butyl peroxynedecanoate, and peroxide Di(2-ethylhexyl) dicarbonate, tert-amyl neopentyl peroxide, tert-butyl neopentyl peroxide, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, tert-amyl-2-ethylhexanoate peroxide, tert-butyl 2-ethylhexanoate peroxide, 1,1-di(tert-amylperoxy)cyclohexane, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)cyclohexane, tert-amyl (2-ethylhexyl) carbonate, OO-tert-butyl-O-isopropyl monoperoxy carbonate, tert-butyl isopropyl carbonate, tert-amyl benzoate peroxide tert-butyl peroxide, tert-butyl peroxide, ethyl 3,3-di(tert-pentylperoxy)butyrate, ethyl 3,3-di(tert-butylperoxy)butyrate, dicumyl peroxide; and azo compounds, such as 4,4'-azobis(4-cyanopentanoic acid), 1,1'-azobis(cyclohexaneformonitrile), azobisisobutyronitrile (AIBN), 2,2'-azobis(2-methylpropanediamine) dihydrochloride, 2,2'-azobis[2-(imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] disulfate dihydrate, 2,2'- 2,2'-Azobis[N-(2-carboxyethyl)-2-methylpropamidinium] hydrate, 2,2'-Azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane} dihydrochloride, 2,2'-Azobis[2-(2-imidazolin-2-yl)propane], 2,2'-Azobis(1-imino-1-pyrrolyl-2-ethylpropane) dihydrochloride, 2,2'-Azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propamide}, 2,2'-Azobis[2-methyl-N-(2-hydroxyethyl)propamide], cumene hydroperoxide, ammonium persulfate, etc.

[0081] For example, the photoinitiator may include 2-hydroxy-2-methylphenylacetone, benzoin ethyl ether, benzoin isobutyl ether, benzoin methyl ether, trienone, 2,2-dimethoxy-2-phenylacetophenone, 3,4-dimethylbenzophenone, 3'-hydroxyacetophenone, etc.

[0082] In an exemplary embodiment, the initiator content may be from 0.1 parts by weight to 10 parts by weight relative to the total weight of 100 parts by weight of the first monomer and the second monomer. In some embodiments, the initiator content may be from 0.5 parts by weight to 7 parts by weight relative to the total weight of 100 parts by weight of the first monomer and the second monomer.

[0083] In an exemplary embodiment, the content of the thermal initiator may be from 0.1 parts by weight to 1 part by weight relative to the total weight of 100 parts by weight of the first monomer and the second monomer.

[0084] In an exemplary embodiment, the content of the photoinitiator may be from 4 to 6 parts by weight relative to the total weight of 100 parts by weight of the first monomer and the second monomer.

[0085] Figure 1 This is a schematic diagram showing a cross-section of a secondary battery according to an exemplary embodiment.

[0086] Reference Figure 1 The secondary battery includes a negative electrode 100, a positive electrode 200, and an electrolyte layer 300.

[0087] The negative electrode 100 may include a lithium metal layer. For example, the negative electrode 100 may include a lithium foil or a lithium alloy layer. The thickness of the lithium foil may be, for example, from 20 μm to 200 μm.

[0088] The positive electrode 200 can be disposed opposite to the negative electrode 100. The positive electrode 200 includes a porous sulfur-containing matrix 205 containing multiple pores. The porous sulfur-containing matrix can form the framework of the positive electrode 200.

[0089] The porous sulfur-containing matrix 205 may contain a plurality of pores 210, and the plurality of pores 210 contain a cured product of the quasi-solid electrolyte forming composition.

[0090] The positive electrode 200 can be manufactured, for example, by coating the composition onto the surface of a porous sulfur-containing substrate 205 and then curing it. The curing method can be thermosetting or photosetting.

[0091] For example, thermosetting can be performed by coating the composition onto the surface of the porous sulfur-containing matrix and placing it at a high temperature.

[0092] For example, photocuring can be performed by coating the composition onto the surface of the porous sulfur-containing matrix and then irradiating it with light. There are no particular limitations on the light source used for irradiation, but for example, an ultraviolet (UV) light source can be used. For example, the wavelength of the UV light source can be from 380 nm to 410 nm, and it can have a wavelength of 1500 mW / cm². 2 Up to 10000mW / cm2 Energy.

[0093] The light irradiation can be carried out for a sufficient time to cure the composition, for example, 20 to 60 seconds.

[0094] According to an exemplary implementation, with Figure 1 Unlike the previous example, the positive electrode may include a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector. The positive electrode active material layer may contain a sulfur-based active material.

[0095] Sulfur-based active materials may include, for example: sulfur; sulfur-carbon composites (composites of sulfur with carbon-based conductive materials such as graphite, carbon black, acetylene black, Ketjen black, graphene, carbon nanotubes, vapor-grown carbon fiber (VGCF), and carbon fiber); sulfur-polyacrylonitrile composites (S-PAN); lithium sulfide (Li2S); etc.

[0096] The positive electrode active material layer may further include conductive materials and / or adhesives.

[0097] The adhesive may include polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, polyacrylonitrile, polymethyl methacrylate, nitrile rubber (NBR), polybutadiene rubber (BR), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), etc.

[0098] The conductive material can be added to enhance the conductivity of the positive electrode active material layer and / or the mobility of lithium ions or electrons. For example, the conductive material may include carbon-based conductive materials such as graphite, carbon black, acetylene black, Ketjen black, graphene, carbon nanotubes, vapor-grown carbon fibers (VGCF), and carbon fibers, and / or metal-based conductive materials including perovskite materials such as tin, tin oxide, titanium oxide, LaSrCoO3, and LaSrMnO3, but is not limited thereto.

[0099] A secondary battery according to an exemplary embodiment includes an electrolyte layer 300 disposed between a negative electrode 100 and a positive electrode 200. The electrolyte layer 300 includes an electrolyte layer comprising a cured product of the quasi-solid electrolyte forming composition.

[0100] For example, the electrolyte layer 300 can be manufactured by coating the composition onto a release film and then curing it.

[0101] According to some embodiments, the electrolyte layer 300 may further comprise a porous polymer matrix. For example, the electrolyte layer 300 may include: a porous polymer matrix comprising a plurality of pores; and a cured composition contained within said plurality of pores. The porous polymer matrix is ​​not particularly limited, but may, for example, comprise a porous polyethylene nonwoven fabric.

[0102] For example, the electrolyte layer 300 can be manufactured by coating the composition onto the surface of the porous polymer matrix and then curing it. The curing method can be thermosetting or photosetting.

[0103] For example, thermosetting can be performed by coating the composition onto the surface of the porous polymer matrix and placing it at a high temperature.

[0104] For example, photocuring can be performed by coating the composition onto the surface of the porous polymer matrix and irradiating it with light. There are no particular limitations on the light source used for irradiation, but for example, an ultraviolet (UV) light source can be used. For example, the wavelength of the UV light source can be from 380 nm to 410 nm, and it can have a wavelength of 1500 mW / cm². 2 Up to 10000mW / cm 2 Energy.

[0105] The light irradiation can be carried out for a sufficient time to cure the composition, for example, 20 to 60 seconds.

[0106] In an exemplary embodiment, the cured product of the quasi-solid electrolyte forming composition may comprise a copolymer of the first monomer and the second monomer. The curing can be performed by applying energy, and the polymerization reaction of the first monomer and the second monomer can be carried out under the action of the initiator. Therefore, a copolymer of the first monomer and the second monomer can be formed.

[0107] According to an exemplary embodiment, the electrolyte layer can be formed using an in-situ process. For example, the secondary battery can be manufactured by stacking a porous sulfur-containing matrix, a porous polymer matrix, and a negative electrode to create an initial electrode assembly, inserting the initial electrode assembly into an outer casing material, injecting the composition, and then curing it to manufacture the secondary battery. In this case, the curing can be performed by thermosetting.

[0108] The secondary battery according to an exemplary embodiment can be a lithium-sulfur battery. During repeated charge-discharge cycles, the lithium-sulfur battery may form lithium polysulfides as a byproduct. The secondary battery according to an exemplary embodiment may include a cured product of the composition, the cured product potentially comprising a copolymer of a first monomer and a second monomer. The ionic functional groups of the first monomer may be highly reactive with the lithium polysulfides, thereby reducing the accumulation of lithium polysulfides within the battery. Therefore, the battery's lifespan characteristics can be improved.

[0109] The embodiments of the present invention will be further described below with reference to specific experimental examples. The embodiments and comparative examples included in the experimental examples are only for illustrating the present invention and are not intended to limit the scope of the claims. Various changes and modifications can be made to the embodiments within the scope of the present invention and its technical concept, which will be obvious to those skilled in the art, and these variations and modifications also fall within the scope of the claims.

[0110] Example 1

[0111] A quasi-solid electrolyte forming composition was prepared by mixing 87 parts by weight of a liquid electrolyte (in which 0.1 M of lithium bis(trifluoromethanesulfonyl)imide and 0.3 M of lithium nitrate were dissolved in a solvent containing 1,3-dioxolane and 1,2-dimethoxyethane in a volume ratio of 1:1), 3 parts by weight of 3-(triallylamyl)propanesulfonate as the first monomer, 10 parts by weight of ethoxylated trimethylolpropane triacrylate as the second monomer, and 0.65 parts by weight of 2-hydroxy-2-methylphenylacetone as the initiator.

[0112] The composition was coated onto the surface of a porous sulfur matrix, and then irradiated with UV light (wavelength 400 nm, energy 5000 mW / cm²). 2 (Wait) 40 seconds, thus creating the positive electrode.

[0113] The composition was coated onto the surface of a porous polyethylene nonwoven fabric, and then irradiated with UV light (wavelength 400 nm, energy 5000 mW / cm²). 2 (etc.) 40 seconds, thereby creating an electrolyte layer.

[0114] The electrolyte layer is stacked on the positive electrode, and then a lithium foil (100 μm thick) is stacked on top to form an electrode assembly. The electrode assembly is then placed in a soft-pack packaging material and sealed to manufacture a battery.

[0115] Example 2

[0116] The composition was prepared by the same method as in Example 1, except that 0.13 parts by weight of azobisisobutyronitrile was used as the initiator instead of 2-hydroxy-2-methylphenylacetone.

[0117] A porous sulfur electrode, a porous polyethylene nonwoven fabric, and a lithium foil are sequentially stacked to form an initial electrode assembly. This initial electrode assembly is then placed in a soft-pack outer casing, and the three sides except for the liquid injection side are sealed. The composition is injected through the liquid injection side and sealed, then placed at 60°C for 3 hours to manufacture a battery.

[0118] Comparative Example 1

[0119] A porous sulfur electrode, a porous polyethylene nonwoven fabric, and a lithium foil are sequentially stacked to form an initial electrode assembly. The initial electrode assembly is placed in a soft-pack outer material and sealed on three sides except for the electrolyte injection side.

[0120] A battery is manufactured by injecting a liquid electrolyte (in which 0.1 M lithium bis(trifluoromethanesulfonyl)imide and 0.3 M lithium nitrate are dissolved in a solvent containing 1,3-dioxolane and 1,2-dimethoxyethane in a volume ratio of 1:1) through the electrolyte injection section and sealing it.

[0121] Comparative Example 2

[0122] The composition and battery were prepared using the same method as in Example 1, except that the first monomer was not used in the composition.

[0123] Experimental Example: Evaluation of Battery Life Characteristics

[0124] For the batteries of the examples and comparative examples, a formation charge-discharge cycle was performed, consisting of charging at a current density of 0.1C and a cutoff voltage of 2.7V, and discharging at a current density of 0.1C and a cutoff voltage of 1.7V. Subsequently, the cycle was repeated 150 times, charging at a current density of 0.5C and a cutoff voltage of 2.7V, and discharging at a current density of 0.5C and a cutoff voltage of 1.7V. The coulombic efficiency and capacity per unit weight of sulfur for each battery were measured.

[0125] Figure 2 The graph shows the capacity and coulombic efficiency of the batteries of Example 1, Comparative Example 1 and Comparative Example 2 according to the cycle.

[0126] Reference Figure 2 Even during repeated charge-discharge cycles, the capacity and coulombic efficiency of the battery in Example 1 remained at a level similar to the initial level. On the other hand, the battery in Comparative Example 1, which contained a liquid electrolyte, experienced a sharp decrease in capacity after approximately 80 cycles, while the battery in Comparative Example 2, which was manufactured without the use of ionic cells, experienced a sharp decrease in capacity after approximately 50 cycles.

[0127] The above description is merely an example of applying the principles of this invention, and other configurations may be further included without departing from the scope of this invention.

Claims

1. A composition for forming a quasi-solid electrolyte, comprising: A liquid electrolyte comprising a lithium salt and an organic solvent; The first monomer has an ionic functional group; The second monomer is different from the first monomer and has cross-linking functional groups; as well as Initiator.

2. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The first monomer comprises: anionic functional group; cationic functional group; or anionic functional group and cationic functional group.

3. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The first monomer contains a nitrogen-based cationic functional group and a thio-based anionic functional group.

4. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The first monomer comprises 3-(triallylammonium)propanesulfonate.

5. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The content of the first monomer is 0.1% to 5% by weight of the total weight of the quasi-solid electrolyte forming composition.

6. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The crosslinking functional group includes (meth)acrylate groups.

7. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The second monomer comprises at least one selected from ethoxylated bisphenol A di(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, (meth)acrylate, carboxyethyl di(meth)acrylate, cyano(meth)acrylate, propylene glycol di(meth)acrylate, polyurethane di(meth)acrylate, neopentyl glycol di(meth)acrylate, isobornyl di(meth)acrylate, isophorone di(meth)acrylate, hexamethylene di(meth)acrylate, phenyl glycidyl ether di(meth)acrylate, and tetraethylene glycol di(meth)acrylate.

8. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The content of the second monomer is 5% to 20% by weight of the total weight of the quasi-solid electrolyte forming composition.

9. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, In the total weight of the quasi-solid electrolyte forming composition, the weight ratio of the second monomer to the weight of the first monomer is 1 to 10.

10. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The initiator includes a thermal initiator or a photoinitiator.

11. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The initiator content is from 0.1 parts by weight to 10 parts by weight relative to the total weight of 100 parts by weight of the first monomer and the second monomer.

12. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The lithium salt comprises a first lithium salt containing an organic anion and a second lithium salt containing an inorganic anion.

13. The composition for forming a quasi-solid electrolyte according to claim 1, wherein, The organic solvents include cyclic ether solvents and straight-chain ether solvents.

14. A secondary battery, comprising: negative electrode; Positive electrode, wherein the positive electrode and the negative electrode are disposed opposite to each other; and An electrolyte layer is disposed between the negative electrode and the positive electrode, and the electrolyte layer comprises a cured product of a quasi-solid electrolyte forming composition. The positive electrode includes: A porous sulfur-containing matrix, the porous sulfur-containing matrix comprising a plurality of pores; and The cured product of the quasi-solid electrolyte forming composition, wherein the cured product of the quasi-solid electrolyte forming composition is contained within the plurality of pores. The quasi-solid electrolyte forming composition comprises: A liquid electrolyte comprising a lithium salt and an organic solvent; The first monomer has an ionic functional group; A second monomer, which differs from the first monomer and has cross-linking functional groups; and Initiator.

15. The secondary battery according to claim 14, wherein, The cured product of the quasi-solid electrolyte forming composition comprises a copolymer of the first monomer and the second monomer.

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