Heterogeneous electrolyte secondary battery and method for manufacturing the same

Abstract

This specification discloses a heterogeneous electrolyte secondary battery comprising a positive electrode impregnated with a positive electrode electrolyte, a negative electrode impregnated with a negative electrode electrolyte, and a separation membrane interposed between the positive and negative electrodes and containing a polymer-based solid electrolyte, wherein the polymer-based solid electrolyte comprises a polymer resin and an electrolyte, and the positive electrode electrolyte and the negative electrode electrolyte have different compositions.

Description

[Technical Field]

[0001] [Cross-reference of related applications] This application claims priority rights based on Korean Patent Application No. 10-2023-0086752 dated 4 July 2023, and all content disclosed in the said Korean Patent Application is incorporated herein as part of this specification.

[0002] This specification discloses a heterogeneous electrolyte secondary battery and a method for manufacturing the same. [Background technology]

[0003] With increasing technological development and demand for electronic devices, the demand for secondary batteries as an energy source has rapidly increased, and among these secondary batteries, lithium-ion batteries, which have high energy density and voltage, have been commercialized and are widely used. Conventionally, liquid electrolytes, particularly ion-conducting organic liquid electrolytes in which salts are dissolved in non-aqueous organic solvents, have been mainly used as electrolytes for lithium-ion batteries. However, such liquid electrolytes have disadvantages, including a high possibility of volatilization of the organic solvent and low stability due to combustion caused by rising ambient temperatures and the temperature of the battery itself. Therefore, recently, research has emerged to commercialize polymer electrolytes, such as gel polymer electrolytes, as an alternative to liquid electrolytes.

[0004] For a battery to operate across a wide operating voltage range, the oxidation and reduction stability of the electrolyte components is crucial. While all conventional secondary batteries use a single electrolyte, some solvents or additives that are expected to significantly improve performance may decompose due to high or low potential side reactions, or form undesirable byproducts, leading to a degradation of battery performance. This can result in the inability to use certain electrolyte components or a limitation of the operating potential, leading to a lower cell voltage.

[0005] On the other hand, lithium-nafion (Li-Nafion) membranes have a relatively high Li content as a polymer solid electrolyte. +In addition to having ionic conductivity, Li + It can selectively permeate ions and suppress the movement of anions, additives, solvents, etc., between the positive and negative electrodes.

[0006] Therefore, there is a need to realize a heterogeneous electrolyte secondary battery that can selectively permeate lithium ions while suppressing the fluidity of the electrolyte within the cell, and that has a wide driving voltage range. [Overview of the project] [Problems that the invention aims to solve]

[0007] Therefore, the present inventors have solved the problem of solvents or additives being decomposed by high-potential or low-potential side reactions, or forming undesirable by-products, which leads to deterioration of battery performance, and provide a heterogeneous electrolyte secondary battery with a wide driving voltage range. [Means for solving the problem]

[0008] The following describes specific embodiments of the invention, such as electrolyte compositions for lithium metal batteries.

[0009] The terms and words used in this specification and in the claims should not be construed to be limited to their ordinary or dictionary meanings, but rather to be interpreted as meanings and concepts consistent with the technical idea of ​​the present invention, based on the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0010] The terms used herein are for illustrative purposes only and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0011] In this specification, terms such as “includes,” “equip,” or “have” are intended to specify the existence of implemented features, figures, stages, components, or combinations thereof, and should be understood not to preemptively exclude the existence or possibility of adding one or more other features, figures, stages, components, or combinations thereof.

[0012] [Heterogeneous electrolyte secondary batteries] According to one embodiment of the present invention, a heterogeneous electrolyte secondary battery is provided, comprising a positive electrode impregnated with a positive electrode electrolyte, a negative electrode impregnated with a negative electrode electrolyte, and a separation membrane interposed between the positive electrode and the negative electrode and containing a polymer-based solid electrolyte, wherein the polymer-based solid electrolyte comprises a polymer resin and an electrolyte, and the positive electrode electrolyte and the negative electrode electrolyte have different compositions.

[0013] [Separation membrane] In exemplary embodiments, the separation membrane may include a polymeric solid electrolyte containing a polymer resin, specifically, the polymeric solid electrolyte may be a polymer electrolyte formed by adding a polymer resin to a solvated lithium salt.

[0014] Therefore, the polymer-based solid electrolyte may contain one or more of a polymer resin, a lithium salt, a polymerization disclosing agent, an additive, and a solvent, and the electrolyte may contain one or more of a lithium salt, a polymerization disclosing agent, an additive, and a solvent. For example, the polymer-based solid electrolyte may be composed of a polymer resin, a lithium salt, and a solvent, thereby maximizing the reduction of resistance.

[0015] In an exemplary embodiment, the separation membrane is made of lithium ions (Li + It may have selective permeability to ).

[0016] In exemplary embodiments, the polymer resin may include a perfluorosulfonic acid resin. For example, the perfluorosulfonic acid resin may be lithiated Nafion.

[0017] In an exemplary embodiment, the separation membrane can be a separation membrane impregnated with the polymer solid electrolyte or the polymer solid electrolyte membrane. For example, as the separation membrane, a normal porous polymer film used as a conventional separation membrane, such as a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, can be used alone or in a laminated form, or a normal porous non-woven fabric, such as a non-woven fabric made of high-melting-point glass fibers, polyethylene terephthalate fibers, etc., can be used, but it is not limited thereto.

[0018] In an exemplary embodiment, the polymer resin content relative to the total weight of the separation membrane can be 10% to 30% by weight. For example, it can be 10% to 20% by weight, 15% to 25% by weight, or 20% to 30% by weight. Within the range of the polymer resin content, only lithium ions can be selectively permeated in the cell to maintain a state where different electrolytes are isolated. FIG. 1 schematically shows the mechanism for suppressing the movement of anions and additives between the positive and negative electrodes in a gel polymer secondary battery, and a gel polymer matrix is densely formed in the pore spaces of the coating layer and the separation membrane so that components larger in size than Li ions are physically isolated between the positive and negative electrodes.

[0019] In an exemplary embodiment, the lithium salt can act as a source of lithium ions in the battery to enable the operation of a basic lithium secondary battery and play a role in promoting the movement of lithium ions between the positive and negative electrodes, and those commonly used in electrolytes for lithium secondary batteries can be used without limitation. For example, the lithium salt contains Li + as a cation and F - 、Cl - 、Br - 、I - 、NO3 - 、N(CN)2 - 、BF4- ClO4 - AlO4 - AlCl4 - PF6 - SbF6 - AsF6 - BF2C2O4 - BC4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - , C4F9SO3 - CF3CF2SO3 - , (CF3SO2)2N - (F2SO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - It may include at least one selected from the group consisting of the following.

[0020] The lithium salt may be used individually or, if necessary, in a mixture of two or more types. The lithium salt can be appropriately modified within a range of normal use, but in order to obtain the optimal effect of forming a protective film on the electrode surface, it may be included in the gel polymer electrolyte composition at a concentration of 0.8 M to 2 M, specifically 0.8 M to 1.5 M.

[0021] Furthermore, in exemplary embodiments of the present invention, the solvent contained in the polymer solid electrolyte is not limited as long as it minimizes decomposition by oxidation reactions during the charging and discharging process of the secondary battery and can exhibit the desired properties together with the additive. For example, ether-based solvents, ester-based solvents, or amide-based solvents can be used individually or in combination of two or more.

[0022] Among the organic solvents mentioned above, the ether-based solvent can be any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, and ethyl propyl ether, or a mixture of two or more of these, but is not limited to this.

[0023] Furthermore, the ester solvent may include at least one compound selected from the group consisting of cyclic carbonate compounds, linear carbonate compounds, linear ester compounds, and cyclic ester compounds.

[0024] Specific examples of the aforementioned cyclic carbonate compounds include any one selected from the group consisting of 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 fluoroethylene carbonate (FEC), or a mixture of two or more of these.

[0025] Furthermore, specific examples of the linear carbonate compounds include, but are not limited to, any one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate, or a mixture of two or more of these.

[0026] Specific examples of the linear ester compounds include, but are not limited to, any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate, or a mixture of two or more of these.

[0027] The cyclic ester compound may, but is not limited to, any one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone, or a mixture of two or more of these.

[0028] Among the ester solvents mentioned above, cyclic carbonate compounds are suitable for use because they are high-viscosity organic solvents with high dielectric constants that effectively dissociate lithium salts in the electrolyte. Furthermore, by mixing such cyclic carbonate compounds with low-viscosity, low-dielectric-constant linear carbonate compounds and linear ester compounds, such as dimethyl carbonate and diethyl carbonate, in appropriate ratios, it is possible to create heterogeneous electrolytes with high electrical conductivity, making them even more suitable for use.

[0029] In exemplary embodiments, the polymerization disclosing agent may be any conventional polymerization disclosing agent well known in the art. For example, typical examples of such polymerization disclosing agents include benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-tert-butyl peroxide, t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide, and hydrogen peroxide. Examples include, but are not limited to, organic peroxides such as peroxides, hydroperoxides, and one or more azo compounds selected from the group consisting of 2,2'-azobis(2-cyanobutane), dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis(methylbutyronitrile), 2,2'-azobis(isobutyronitrile) (AIBN; 2,2'-Azobis(iso-butyronitrile)), and 2,2'-azobisdimethyl-valeronitrile (AMVN; 2,2'-Azobisdimethyl-Valeronitrile).

[0030] The polymerizing agent can be decomposed in the battery by heat, specifically by temperatures of 30°C to 100°C, or more precisely, 60°C to 80°C, or by decomposition at room temperature (5°C to 30°C) to form radicals. These radicals then react with polymerizable oligomers through free radical polymerization to form a gel polymer electrolyte.

[0031] The polymerization disclosing agent may be included in an amount of 0.1 to 5 parts by weight per 100 parts by weight of the oligomer. If the polymerization disclosing agent exceeds 5 parts by weight, unreacted polymerization disclosing agent may remain during the production of the gel polymer electrolyte, adversely affecting battery performance. Conversely, if the polymerization disclosing agent is less than 0.1 parts by weight, there is a problem that gelation may not occur properly even under conditions above a certain temperature.

[0032] Selectively, the polymeric solid electrolyte may further contain additional additives. Examples of additional additives usable in this invention include vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, vinylethylene carbonate, cyclic sulfite, saturated sultone, unsaturated sultone, and acyclic sulfone, each used individually or in combination of two or more.

[0033] Examples of cyclic sulfites include ethylene sulfite, methyl ethylene sulfite, ethyl ethylene sulfite, 4,5-dimethylethylene sulfite, 4,5-diethyl ethylene sulfite, propylene sulfite, 4,5-dimethylpropylene sulfite, 4,5-diethylpropylene sulfite, 4,6-dimethylpropylene sulfite, 4,6-diethylpropylene sulfite, and 1,3-butylene glycol sulfite. Examples of saturated sultones include 1,3-propanesultone and 1,4-butanesultone. Examples of unsaturated sultones include ethensultone, 1,3-propensultone, 1,4-butensultone, and 1-methyl-1,3-propensultone. Examples of acyclic sulfones include divinyl sulfone, dimethyl sulfone, methyl ethyl sulfone, and methyl vinyl sulfone.

[0034] The aforementioned additional additives may be mixed from two or more types and present in an amount of 0.01% to 5% by weight, specifically 0.01% to 3% by weight, based on the total amount of the polymer solid electrolyte, preferably 0.05% to 3% by weight. If the content of the additional additives is less than 0.01% by weight, the effect of improving the low-temperature output, high-temperature storage characteristics, and high-temperature life characteristics of the battery will be minimal, and if the content of the additional additives exceeds 5% by weight, excessive side reactions may occur in the electrolyte during charging and discharging of the battery. In particular, if an excessive amount of the SEI film-forming additive is added, it may not decompose sufficiently at high temperatures and may remain unreacted or precipitated in the electrolyte at room temperature. This may cause side reactions that reduce the life or resistance characteristics of the secondary battery.

[0035] [Positive electrode] In a heterogeneous electrolyte secondary battery according to an embodiment of the present invention, the positive electrode can be manufactured by forming a positive electrode mixture layer on a positive electrode current collector and then impregnating the positive electrode electrolyte with the mixture. The positive electrode mixture layer can be formed by coating a positive electrode slurry containing a positive electrode active material, a binder, a conductive material, and a solvent onto a positive electrode current collector, followed by drying and rolling.

[0036] In exemplary embodiments, the cathode electrolyte may include a lithium salt, a solvent, and selective additives. In this case, the cathode electrolyte (Catholyte) may include a solvent or cathode film-forming material with low reduction stability. The additives and / or solvents applied to the cathode electrolyte may be the same as those applied to polymer solid electrolytes described above.

[0037] On the other hand, the positive electrode electrolyte and the negative electrode electrolyte can have different compositions from each other, for example, the type and / or concentration of lithium salt may differ from each other, and the preferred positive and negative electrode electrolyte compositions can vary depending on the cell design and the functionality to be pursued. For example, in the case of a Si-rich cell, an excess amount of cyclic carbonate compound (e.g., FEC) must be added to continuously form a film that suppresses side reactions caused by active material cracking during charging and discharging, but this has no functionality at the positive electrode and increases the resistance of the cell as a whole. In this case, an electrolyte composition with an excess amount of cyclic carbonate compound such as FEC can be applied to the negative electrode, and an electrolyte composition with high potential stability and low ionic conductivity can be applied to the positive electrode.

[0038] In an exemplary embodiment, the lithium salt contained in the positive electrode electrolyte is Li as a cation. + It contains F as an anion. - Cl - , Br - , I - NO3 - , N(CN)2 - BF4 - ClO4 - AlO4- AlCl4 - PF6 - SbF6 - AsF6 - BF2C2O4 - BC4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - , C4F9SO3 - CF3CF2SO3 - , (CF3SO2)2N - (F2SO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - It may include at least one selected from the group consisting of the following.

[0039] The lithium salt may be used individually or, if necessary, in a mixture of two or more types. The lithium salt can be appropriately changed within a range that is normally usable, but in order to obtain the optimal effect of forming a protective film on the electrode surface, it may be included in the positive electrode electrolyte at a concentration of 0.8 M to 2 M, specifically 0.8 M to 1.5 M.

[0040] The positive electrode current collector is not particularly limited as long as it is conductive but does not induce a chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc., can be used.

[0041] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium composite metal oxide containing one or more metals such as cobalt, manganese, nickel or aluminum and lithium. More specifically, the lithium composite metal oxide is a lithium-manganese-based oxide (for example, LiMnO2, LiMn2O4, etc.), a lithium-cobalt-based oxide (for example, LiCoO2, etc.), a lithium-nickel-based oxide (for example, LiNiO2, etc.), a lithium-nickel-manganese-based oxide (for example, LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-Z Ni Z O4 (where 0 < Z < 2), etc.), a lithium-nickel-cobalt-based oxide (for example, LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), a lithium-manganese-cobalt-based oxide (for example, LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O4 (where 0 < Z1 < 2), etc.), a lithium-nickel-manganese-cobalt-based oxide (for example, Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.), or a lithium-nickel-cobalt-transition metal (M) oxide (for example, Li(Ni p2 Co q2 Mn r3 M s2)O2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are the atomic fractions of independent elements respectively, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc.) and the like can be mentioned, and one or more of these compounds may be included.

[0042] Among these, from the viewpoint of being able to enhance the capacity characteristics and safety of the battery, the lithium composite metal oxide is LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (for example, Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2 and Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc.), or lithium nickel cobalt aluminum oxide (for example, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.) and the like.

[0043] The positive electrode active material may be contained at 80% to 99.5% by weight, specifically 85% to 95% by weight, based on the total weight of the solid content in the positive electrode slurry.

[0044] When the content of the positive electrode active material is 80% by weight or less, the energy density may be low and the capacity may decrease.

[0045] The binder is a component that assists in the bonding of the active material to the conductive material and to the current collector, and is usually added at a concentration of 1% to 30% by weight based on the total weight of solids in the positive electrode slurry. More specifically, it is added at a concentration of 1 to 50 parts by weight, or 3 to 15 parts by weight, based on the total weight of solids in the positive electrode slurry. If the amount of binder is less than 1 part by weight, the adhesion between the electrode active material and the current collector may be insufficient, and if it exceeds 50 parts by weight, the adhesion will improve, but the amount of electrode active material will decrease accordingly, which may reduce the battery capacity.

[0046] Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-dientelpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers.

[0047] Furthermore, the conductive material is a substance that imparts conductivity to the battery without inducing any chemical changes, and can be added in an amount of 1% to 20% by weight based on the total weight of solids in the positive electrode slurry.

[0048] Typical examples of such conductive materials include carbon powders such as carbon black, acetylene black, Ketjenblack, channel black, furnace black, lamp black, or thermal black; graphite powders such as natural graphite, artificial graphite, or graphite with a highly developed crystalline structure; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. Examples of such conductive materials include acetylene black-based conductive materials (manufactured by Chevron Chemical Company, Denka Black (manufactured by Denka Singapore Private Limited), or Gulf Oil Company), Ketjenblack, EC-based materials (manufactured by Armak Company), and Vulcan XC-72 (manufactured by Cabot Company). You can also use products currently on the market under names such as (manufactured by Timcal Company) and Super-P (manufactured by Timcal).

[0049] The solvent may include organic solvents such as N-methyl-2-pyrrolidone (NMP), and can be used in an amount that results in a suitable viscosity when the positive electrode active material and selectively include binders and conductive materials. For example, the solvent may be included such that the solid content concentration in the slurry containing the positive electrode active material and selectively including binders and conductive materials is 10% to 60% by weight, preferably 20% to 50% by weight.

[0050] [Negative electrode] In a heterogeneous electrolyte secondary battery according to an embodiment of the present invention, the negative electrode can be manufactured by forming a negative electrode mixture layer on a negative electrode current collector and then impregnating the negative electrode electrolyte with it. The negative electrode mixture layer can be formed by coating a negative electrode slurry containing a negative electrode active material, a binder, a conductive material, and a solvent onto a negative electrode current collector, followed by drying and rolling.

[0051] In exemplary embodiments, the anolyte may include a lithium salt, a solvent, and selective additives. In this case, the anolyte may include a solvent or film-forming material with low oxidation stability. The additives and / or solvents applied to the anolyte may be the same as those applied to the polymer solid electrolytes described above.

[0052] In an exemplary embodiment, the lithium salt contained in the negative electrode electrolyte is Li as a cation. + It contains F as an anion. - Cl - , Br - , I - NO3 - , N(CN)2 - BF4 - ClO4 - AlO4 - AlCl4 - PF6 - SbF6 - AsF6 - BF2C2O4 - BC4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - , C4F9SO3 - CF3CF2SO3 - , (CF3SO2)2N - (F2SO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH -CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - It may include at least one selected from the group consisting of the following.

[0053] The lithium salt may be used individually or, if necessary, in a mixture of two or more types. The lithium salt can usually be appropriately modified within a usable range, but in order to obtain the optimal effect of forming a protective film on the electrode surface, it may be included in the negative electrode electrolyte at a concentration of 0.8 M to 2 M, specifically 0.8 M to 1.5 M.

[0054] The negative electrode current collector can generally have a thickness of 3 μm to 500 μm. Such a negative electrode current collector is not particularly limited as long as it does not induce chemical changes in the battery but has high conductivity, and can be made of materials such as copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy. Also, similar to the positive electrode current collector, fine irregularities can be formed on the surface to strengthen the bonding force of the negative electrode active material, and it can be used in a variety of forms such as film, sheet, foil, net, porous material, foam, and nonwoven fabric.

[0055] Furthermore, the negative electrode active material may include at least one selected from the group consisting of lithium metal, carbon materials capable of reversibly intercalating / deintercalating lithium ions, metals or alloys of these metals with lithium, metal composite oxides, materials capable of doping and dedoping lithium, and transition metal oxides.

[0056] As the carbon material capable of reversibly intercalating / deintercalating the lithium ions, any carbon-based negative electrode active material generally used in lithium ion secondary batteries can be used without particular limitation, and typical examples thereof include crystalline carbon, amorphous carbon, or these can be used together. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flaky, spherical or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0057] As the metal or an alloy of these metals and lithium, a metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn or an alloy of these metals and lithium can be used.

[0058] Examples of the metal composite oxide include PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3(0≦x≦1), Li x WO2(0≦x≦1), and Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, elements of Group 1, Group 2, Group 3 of the periodic table, halogen; 0<x≦1; 1≦y≦3; 1≦z≦8) can be selected and used from the group consisting of these.

[0059] As the substance capable of doping and undoping lithium, Si, SiO x(0 < x < 2), Si-Y alloy (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Si), Sn, SnO2, Sn-Y (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Sn), etc. may be mentioned, and it is also possible to mix and use at least one of these with SiO2. As the element Y, Mg, Ca, Sr, Ba, Ra, Sc, Y (yttrium), Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof can be selected.

[0060] Examples of the transition metal oxide include lithium-containing titanium composite oxide (LTO), vanadium oxide, lithium vanadium oxide, etc.

[0061] The negative electrode active material may be contained at 80% to 99% by weight based on the total weight of the solid content in the negative electrode slurry.

[0062] The binder is a component that helps bind the conductive material, the active material, and the current collector, and is usually added at 1% to 30% by weight based on the total weight of the solid content in the negative electrode slurry. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers thereof, etc.

[0063] The conductive material can be the same substance used in the manufacture of the positive electrode and can be added in an amount of 1% to 20% by weight based on the total weight of the solid content in the negative electrode slurry.

[0064] The solvent may include water or an organic solvent such as NMP (N-methyl-2-pyrrolidone), and can be used in an amount that results in a suitable viscosity when it includes the negative electrode active material, and optionally a binder and conductive material. For example, the solid content containing the negative electrode active material, and optionally a binder and conductive material, may be included in a concentration of 50% to 95% by weight, preferably 70% to 90% by weight.

[0065] In exemplary embodiments, the first gel polymer and the second gel polymer may be the same substance or different substances. On the other hand, the content of the first gel polymer in the positive electrode electrolyte and the content of the second gel polymer in the negative electrode electrolyte may be substantially the same or different. In other words, the content of the first gel polymer in the positive electrode electrolyte may be greater than or less than the content of the second gel polymer in the negative electrode electrolyte.

[0066] In exemplary embodiments, the separation membrane can be in direct contact with the positive electrode and the negative electrode. Specifically, an additional layer may not be required between the separation membrane and the positive electrode, or between the separation membrane and the negative electrode, thereby allowing at least a portion of the separation membrane to be in direct contact with the positive and negative electrodes. Thus, in the heterogeneous electrolyte secondary battery according to the embodiment of the present invention, the positive electrode / separation membrane / negative electrode can be cured in a pressed state to impart adhesive force, thereby potentially eliminating the need for a separate adhesive material or lamination process.

[0067] [Manufacturing method for heterogeneous electrolyte secondary batteries] According to another embodiment of the present invention, a method for manufacturing a heterogeneous electrolyte secondary battery is provided, comprising the steps of: preparing a positive electrode and a negative electrode by impregnating a spare positive electrode and a spare negative electrode into a positive electrode electrolyte and a negative electrode electrolyte, respectively; impregnating a separation membrane into a polymer-based solid electrolyte or preparing an electrolyte layer with a polymer-based solid electrolyte membrane; and sequentially stacking the positive electrode, the electrolyte layer, and the negative electrode.

[0068] In the manufacturing method according to the embodiment of the present invention, the assembly process follows the pre-impregnation of the electrode and the separation membrane, thus enabling a reduction in the amount of electrolyte used by minimizing the use of electrolytes, and thus offering advantages in terms of safety and cost. Furthermore, except for the electrode electrolyte impregnation and crosslinking processes, the current mass production process can be used identically, and therefore, no additional or modified special equipment is required.

[0069] First, the positive electrode and negative electrode can be prepared by impregnating them with a positive electrode electrolyte and a negative electrode electrolyte, respectively. Specifically, a pre-positive electrode manufactured by forming a positive electrode mixture layer on a positive electrode current collector can be impregnated with a positive electrode electrolyte containing a first gel polymer, and a pre-negative electrode manufactured by forming a negative electrode mixture layer on a negative electrode current collector can be impregnated with a negative electrode electrolyte containing a second gel polymer. Such impregnation can be carried out using methods commonly used in the art.

[0070] In exemplary embodiments, the impregnation step can be carried out at room temperature for 2 to 48 hours to ensure uniform impregnation of the entire positive and negative electrodes. The content of the first gel polymer relative to the total weight of the impregnated positive electrode may be 0.1% to 10% by weight, and the content of the second gel polymer relative to the total weight of the impregnated negative electrode may be 0.1% to 10% by weight.

[0071] Furthermore, the separation membrane can be impregnated with a polymer-based solid electrolyte, or the electrolyte layer can be prepared with a polymer-based solid electrolyte membrane. Specifically, the separation membrane and polymer-based solid electrolyte may be the same as those described above, and may be impregnated in the same manner as the electrodes. Such a separation membrane can minimize the increase in resistance by using a separation membrane impregnated with a minimum amount of high-content polymer-based solid electrolyte or a high-content gel polymer thin film.

[0072] Next, the positive electrode, the separator membrane, and the negative electrode can be stacked in order and cured. For example, the positive electrode, the separator membrane, and the negative electrode can be arranged in order to form an electrode assembly. Specifically, the electrode assembly may be a laminated structure comprising two types of electrodes, a positive electrode and a negative electrode, and an electrolyte layer as a separator membrane, which is interposed between the electrodes to insulate them from each other, or is placed on top of or below one of the electrodes. The laminated structure may be in a variety of forms, not limited to the case where positive and negative electrodes of a predetermined standard are stacked with a separator membrane in between, or wound in a jelly roll form. Positive electrode tabs and negative electrode tabs may be connected to the electrode assembly. Specifically, the positive electrode tabs and negative electrode tabs are connected to the positive and negative electrodes of the electrode assembly, respectively, and can protrude to the outside of the secondary battery case, becoming pathways through which electrons can move.

[0073] Subsequently, the stacked positive electrode, separation membrane, and negative electrode can be cured. Specifically, the positive electrode electrolyte impregnated in the positive electrode, the negative electrode electrolyte impregnated in the negative electrode, and the polymer solid electrolyte of the separation membrane can be cured. This curing step can be carried out by a thermosetting process. [Effects of the Invention]

[0074] As described above, the gel polymer secondary battery according to the embodiment of the present invention can selectively permeate only lithium ions within the cell and maintain a state in which different electrolytes are isolated by applying a high-content polymer solid electrolyte to the separation membrane and suppressing the movement of large molecular weight substances between the positive and negative electrodes. Furthermore, by utilizing a polymer solid electrolyte impregnated separation membrane such as lithium Nafion, the composition of the positive and negative electrode electrolytes can be different, and solvents, salts, additives, etc., that have low oxidation and reduction stability at specific potentials can be used without side reactions over a wide driving voltage range. [Brief explanation of the drawing]

[0075] [Figure 1] The mechanism for suppressing the movement of anions and additives between the positive and negative electrodes in a heterogeneous electrolyte secondary battery according to an embodiment of the present invention is schematically shown. [Figure 2] The charge-discharge analysis results of heterogeneous electrolyte secondary batteries according to Examples 1-3 of the present invention are shown in a comparative diagram. [Figure 3] The charge-discharge analysis results of heterogeneous electrolyte secondary batteries according to Examples 1-3 of the present invention are shown in a comparative diagram. [Modes for carrying out the invention]

[0076] The following describes in detail embodiments of the present invention so that they can be easily implemented by a person with ordinary skill in the art to which the invention pertains. However, the present invention can be embodied in various different forms and is not limited to the embodiments described herein.

[0077] [Example 1: Cell with heterogeneous gel electrolyte] A positive electrode electrolyte was prepared by dissolving 1M LiPF6 in a solvent (ethylene carbonate (EC):propylene carbonate (PC) = 5:5 volume ratio) and adding 0.06 wt% AIBN as a polymerization revealing agent, and an NCM811 positive electrode was impregnated therein. Similarly, a negative electrode electrolyte was prepared by dissolving 2M LiFSI in a solvent (ethylene carbonate (EC):propylene carbonate (PC) = 5:5 volume ratio) and adding 0.06 wt% AIBN as a polymerization revealing agent, and a graphite negative electrode was impregnated therein.

[0078] Furthermore, a polymeric solid electrolyte composition was prepared by adding 20% ​​by weight of lithium-nafion (Li-Nafion) and 0.06% by weight of AIBN as a polymerization disclosure agent to the NMP solvent, and the PP separation membrane was impregnated therein. After impregnation of the separation membrane, it was vacuum-dried at 100°C for 12 hours to remove the NMP solvent.

[0079] The prepared materials were sequentially stacked in the order of positive electrode / separation membrane / negative electrode, pressed, and then heat-cured at 60°C for 5 hours to produce a "Set1" full cell.

[0080] [Example 2: Cell with heterogeneous gel electrolyte membrane] A full cell of "Set2" was manufactured in the same manner as in Example 1, except that a lithium-ion Nafion membrane was used as the polymer solid electrolyte (Nafion membrane purchased from Sigma-aldrich, which was lithium-ionized by reacting it with a 1M LiOH solution) (lithium-ion Nafion membrane: 13 μm, membrane: approximately 70 μm).

[0081] [Example 3: Cell with heterogeneous gel electrolyte] A full cell of "Set3" was manufactured in the same manner as in Example 1, except that a PP separation membrane was used in which a polymer solid electrolyte was not impregnated into the composition.

[0082] [Experimental Example 1: Charge / Discharge Analysis] The charge and discharge efficiency of the secondary batteries manufactured in Examples 1 to 3 was evaluated, and the results are shown in Figure 2. Specifically, each sample from Examples 1 to 3 was charged to 4.20V with a constant current of 0.1C, then left for 30 minutes, and finally discharged to 2.5V with a constant current of 0.1C to observe the charge and discharge characteristics in the first cycle.

[0083] Furthermore, the samples from Examples 1 to 3 underwent two charge-discharge cycles at an initial temperature of 0.1C, followed by three charge-discharge cycles each at 0.33C. The charging and discharging cycles were repeated, and the discharge capacity was measured for each cycle, as shown in Figure 3.

[0084] During the initial charging process, the PC will have a Li-ion battery. + Li-(PC) is coordinated with n In this form, it penetrates into the negative electrode graphite lattice structure, causing structural damage and delamination, leading to a decrease in capacity. However, if 2M LiFSI is applied, Li + - The number of coordinates between PCs decreases, and the performance degradation due to decoupling is significantly reduced.

[0085] Referring to Figures 2 and 3, it was confirmed that in Example 1 (Set 1), the movement of the electrolyte impregnated in the positive electrode through the separation membrane was blocked, and in Example 2 (Set 2), the movement through the different gel electrolyte membrane was blocked. However, in the case of Example 2 (Set 2), the thick membrane prevents the mutual movement of electrolytes, while in Example 3 (Set 3), the electrolyte impregnated in the positive electrode moves and mixes with the electrolyte impregnated in the negative electrode, showing a significant decrease in capacity and lifespan. This confirms that the lithium Nafion or lithium Nafion membrane impregnated in the separation membrane effectively blocks mass transfer between the positive and negative electrodes.

[0086] Therefore, the gel polymer secondary battery according to the present invention can maintain the isolation of heterogeneous electrolytes between the positive and negative electrodes by applying a separation membrane impregnated with lithium Nafion, thereby achieving a wide driving voltage range and an effect of reducing the amount of electrolyte.

Claims

1. A positive electrode impregnated with a positive electrode electrolyte, A negative electrode impregnated with a negative electrode electrolyte, A separation membrane containing a polymer solid electrolyte is interposed between the positive electrode and the negative electrode, and includes: The polymer-based solid electrolyte comprises a polymer resin and an electrolyte, and the positive electrode electrolyte and the negative electrode electrolyte have different compositions, in a heterogeneous electrolyte secondary battery.

2. The heterogeneous electrolyte secondary battery according to claim 1, wherein the separation membrane is a separation membrane impregnated with the polymer-based solid electrolyte or a polymer-based solid electrolyte membrane.

3. The heterogeneous electrolyte secondary battery according to claim 1, wherein the polymer resin includes a perfluorosulfonic acid resin.

4. The heterogeneous electrolyte secondary battery according to claim 3, wherein the perfluorosulfonic acid resin is lithium-ion Nafion.

5. The heterogeneous electrolyte secondary battery according to claim 1, wherein the polymer resin content relative to the total weight of the separation membrane is 10% to 30% by weight.

6. The heterogeneous electrolyte secondary battery according to any one of claims 1 to 5, wherein the polymer resin content relative to the total weight of the separation membrane is 15% to 25% by weight.

7. The positive electrode electrolyte and the negative electrode electrolyte are LiSCN, LiN(CN) ２ , LiClO ４ , LiBF ４ , LiAsF ６ , LiPF ６ , LiCF ３ SO ３ , LiC(CF ３ SO ２ ) ３ , LiN(SO ２ C ２ F ５ ) ２ , LiN(SO ２ CF ３ ) ２ , LiN(SO ２ F) ２ , LiSbF ６ , LiPF ３ (CF ２ CF ３ ) ３ , LiPF ３ (CF ３ ) ３ and LiB(C ２ O ４ ) ２ The secondary battery with a heterogeneous electrolyte system according to claim 1, comprising one or more lithium salts selected from the group consisting of

8. The heterogeneous electrolyte secondary battery according to claim 7, wherein the positive electrode electrolyte and the negative electrode electrolyte each contain different lithium salts.

9. The heterogeneous electrolyte secondary battery according to claim 7, wherein the positive electrode electrolyte contains a lithium salt at a concentration of 0.1 M to 2 M.

10. The heterogeneous electrolyte secondary battery according to claim 7, wherein the negative electrode electrolyte contains a lithium salt at a concentration of 1 M to 3 M.

11. The separation membrane contains lithium ions (Li ＋ A heterogeneous electrolyte secondary battery according to claim 1, which has selective permeability to ).

12. The separation membrane is in direct contact with the positive electrode and the negative electrode, as described in claim 1, for a heterogeneous electrolyte secondary battery.

13. The steps include: preparing the positive and negative electrodes by impregnating the spare positive electrode and spare negative electrode with the positive electrode electrolyte and negative electrode electrolyte, respectively; The process involves impregnating a separation membrane with a polymer-based solid electrolyte, or preparing an electrolyte layer with a polymer-based solid electrolyte membrane. A method for manufacturing a heterogeneous electrolyte secondary battery, comprising the step of sequentially stacking the positive electrode, the electrolyte layer, and the negative electrode.

Images