Heterogeneous electrolyte-based secondary battery and method for manufacturing same

Abstract

The present specification relates to a heterogeneous electrolyte-based secondary battery comprising: a positive electrode impregnated with a positive electrode electrolyte; a negative electrode impregnated with a negative electrode electrolyte; and a separator interposed between the positive electrode and the negative electrode and including a polymer-based solid electrolyte, wherein the polymer-based solid electrolyte includes a polymer resin and an electrolyte, and the positive electrode electrolyte and the negative electrode electrolyte have different compositions.

Description

Heterogeneous electrolyte secondary battery and its manufacturing method

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0086752, filed July 4, 2023, the entire contents of which are incorporated herein by reference.

[0003] This specification discloses a heteroelectrolyte secondary battery and a method for manufacturing the same.

[0004] As technological development and demand for electronic devices increase, the demand for secondary batteries as an energy source is rapidly increasing. Among these secondary batteries, lithium secondary batteries with high energy density and voltage have been commercialized and widely used. Previously, liquid electrolytes, especially ion-conducting organic liquid electrolytes in which salts are dissolved in non-aqueous organic solvents, have been mainly used as electrolytes in lithium secondary batteries. However, these liquid electrolytes have the disadvantage of low stability due to the high possibility of organic solvent volatilization and combustion caused by increases in the ambient temperature and the temperature of the battery itself. Therefore, research has recently emerged to commercialize polymer electrolytes, such as gel polymer electrolytes, instead of liquid electrolytes.

[0005] For batteries to operate over a wide operating voltage range, the oxidation and reduction stability of electrolyte components is crucial. All conventional secondary batteries utilize a single electrolyte. However, some solvents or additives, which are expected to significantly improve performance, can decompose or form undesirable byproducts due to high- or low-potential side reactions, leading to deterioration of battery performance. This can lead to the inability to use certain electrolyte components or limit operating potentials, resulting in lower cell voltage.

[0006] Meanwhile, the lithiated Nafion (Li-Nafion) membrane is a polymer-based solid electrolyte with a relatively high Li + Not only does it have ionic conductivity, Li + It can selectively transmit ions and inhibit the movement of anions, additives, solvents, etc. between the anode and cathode.

[0007] Accordingly, there is a demand for the implementation of a heterogeneous electrolyte secondary battery that can selectively transmit lithium ions while suppressing the flow of electrolyte within the cell and has a wide operating voltage range.

[0008] Accordingly, the inventors of the present invention aim to provide a heteroelectrolyte secondary battery having a wide operating voltage range by solving the problem that solvents or additives are decomposed by high- or low-potential side reactions or form unwanted byproducts, thereby causing deterioration of battery performance.

[0009] Hereinafter, an electrolyte composition for a lithium metal battery according to a specific embodiment of the invention will be described.

[0010] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0011] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0012] In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0013]

[0014] Heterogeneous electrolyte secondary battery

[0015] According to one embodiment of the present invention, a heteroelectrolyte secondary battery is provided, which comprises: a positive electrode impregnated with a positive electrolyte; a negative electrode impregnated with a negative electrolyte; and a separator interposed between the positive electrode and the negative electrode and including a polymer-based solid electrolyte including a polymer resin; wherein the positive electrode electrolyte and the negative electrode electrolyte have different compositions.

[0016]

[0017] membrane

[0018] In an exemplary embodiment, the separator may include a polymer-based solid electrolyte including a polymer resin, and specifically, the polymer-based solid electrolyte may be a polymer electrolyte formed by adding a polymer resin to a solvated lithium salt.

[0019] Accordingly, the polymer-based solid electrolyte may include at least one of a polymer resin, a lithium salt, a polymerization initiator, an additive, and a solvent, and the electrolyte may include at least one of a lithium salt, a polymerization initiator, 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 minimizing resistance.

[0020] In an exemplary embodiment, the separator comprises lithium ions (Li + ) may have selective permeability.

[0021] In an exemplary embodiment, the polymer resin may comprise a perfluorosulfonic acid resin. For example, the perfluorosulfonic acid resin may be lithiated Nafion.

[0022] In an exemplary embodiment, the separator may be a separator impregnated with the polymer-based solid electrolyte or the polymer-based solid electrolyte membrane. For example, the separator may be a conventional porous polymer film used as a separator in the past, for example, a porous polymer film made of a polyolefin polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or the like, alone or in a laminated manner, or a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, or the like, may be used, but is not limited thereto.

[0023] In an exemplary embodiment, the polymer resin content with respect to the total weight of the separator may be 10 to 30 wt%. For example, it may be 10 to 20 wt%, 15 to 25 wt%, or 20 to 30 wt%. In the above polymer resin content range, only lithium ions can be selectively permeated within the cell, thereby maintaining the isolation of the heterogeneous electrolyte. Figure 1 schematically illustrates a mechanism for inhibiting the movement of anions and additives between the positive and negative electrodes in a gel polymer secondary battery, wherein a gel polymer matrix is ​​densely formed in the pore spaces of the coating layer and the separator, so that components larger in size than Li ions are physically isolated between the positive and negative electrodes.

[0024] In an exemplary embodiment, the lithium salt may serve as a source of lithium ions within the battery to enable the operation of a basic lithium secondary battery and may serve to promote the movement of lithium ions between the positive and negative electrodes, and those commonly used in electrolytes for lithium secondary batteries may be used without limitation. For example, the lithium salt may be a cation, Li + , and 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 .

[0025] The above lithium salt may be used alone or in combination of two or more as needed. The lithium salt may be appropriately varied within a generally usable range, but in order to obtain an optimal effect of forming a film to prevent corrosion 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.

[0026] Furthermore, in an exemplary embodiment of the present invention, the solvent included in the polymer-based solid electrolyte is not limited as long as it can minimize decomposition due to oxidation reactions or the like during the charge / discharge process of the secondary battery and can exhibit the desired properties together with additives. For example, ether-based solvents, ester-based solvents, or amide-based solvents can be used singly or in combination of two or more.

[0027] Among the above organic solvents, the ether solvent may 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 thereof, but is not limited thereto.

[0028] Additionally, the ester solvent may include at least one compound selected from the group consisting of a cyclic carbonate compound, a linear carbonate compound, a linear ester compound, and a cyclic ester compound.

[0029] Specific examples of the cyclic carbonate compound include 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 thereof.

[0030] In addition, specific examples of the linear carbonate compound may include, but are not limited to, one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, or a mixture of two or more thereof.

[0031] Specific examples of the linear ester compound include, but are not limited to, 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 thereof.

[0032] The above cyclic ester compound may be 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 thereof, but is not limited thereto.

[0033] Among the above ester solvents, cyclic carbonate compounds are preferably used because they are high-viscosity organic solvents with high dielectric constants and thus easily dissociate lithium salts in the electrolyte. When these cyclic carbonate compounds are mixed with low-viscosity, low-dielectric constant linear carbonate compounds and linear ester compounds, such as dimethyl carbonate and diethyl carbonate, in an appropriate ratio, a heterogeneous electrolyte with high electrical conductivity can be produced, and thus they can be used more preferably.

[0034] In an exemplary embodiment, the polymerization initiator may be a conventional polymerization initiator known in the art. For example, representative examples of the polymerization initiator include organic peroxides or hydroperoxides such as benzoyl peroxide, acetyl peroxide, dilauryl peroxide, di-tert-butyl peroxide, t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide, and hydrogen peroxide, and 2,2'-azobis(2-cyanobutane), dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis(methylbutyronitrile), 2,2'-azobis(isobutyronitrile) (AIBN; One or more azo compounds selected from the group consisting of 2,2'-Azobis(iso-butyronitrile) and 2,2'-azobisdimethyl-valeronitrile (AMVN; 2,2'-Azobisdimethyl-Valeronitrile), but is not limited thereto.

[0035] The above polymerization initiator can be decomposed by heat within the battery, for example, heat of 30°C to 100°C, specifically 60°C to 80°C, or decomposed at room temperature (5°C to 30°C) to form radicals, and the polymerizable oligomer can react by free radical polymerization to form a gel polymer electrolyte.

[0036] The above polymerization initiator may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the above oligomer. If the amount of the polymerization initiator exceeds 5 parts by weight, unreacted polymerization initiator may remain during the manufacture of the gel polymer electrolyte, which may adversely affect battery performance. Conversely, if the amount of the polymerization initiator is less than 0.1 parts by weight, there is a problem in that gelation does not occur well even under conditions above a certain temperature.

[0037] Optionally, the polymer-based solid electrolyte may further include additional additives. Additional additives usable in the present invention include vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, vinylethylene carbonate, cyclic sulfite, saturated sultone, unsaturated sultone, acyclic sulfone, and the like, which may be used singly or in combination of two or more.

[0038] At this time, the cyclic sulfites include ethylene sulfite, methyl ethylene sulfite, ethyl ethylene sulfite, 4,5-dimethyl ethylene sulfite, 4,5-diethyl ethylene sulfite, propylene sulfite, 4,5-dimethyl propylene sulfite, 4,5-diethyl propylene sulfite, 4,6-dimethyl propylene sulfite, 4,6-diethyl propylene sulfite, 1,3-butylene glycol sulfite, etc., the saturated sultones include 1,3-propane sultone, 1,4-butane sultone, etc., the unsaturated sultones include ethene sultone, 1,3-propene sultone, 1,4-butene sultone, 1-methyl-1,3-propene sultone, etc., and the acyclic sulfones include divinyl sulfone, dimethyl sulfone, diethyl sulfone, methylethyl sulfone, methylvinyl Examples include sulfone.

[0039] The above-mentioned additional additives may be mixed in two or more kinds and included in an amount of 0.01 to 5 wt%, specifically 0.01 to 3 wt%, based on the total amount of the polymer-based solid electrolyte, and preferably 0.05 to 3 wt%. If the content of the above-mentioned additional additive is less than 0.01 wt%, the effect of improving the low-temperature output of the battery and the high-temperature storage characteristics and high-temperature life characteristics is minimal, and if the content of the above-mentioned additional additive exceeds 5 wt%, there is a possibility that side reactions may occur excessively in the electrolyte during charge and discharge of the battery. In particular, when the above-mentioned SEI film forming additives are added in excessive amounts, they may not be sufficiently decomposed at high temperatures and may remain unreacted or precipitated in the electrolyte at room temperature. Accordingly, side reactions that reduce the life or resistance characteristics of the secondary battery may occur.

[0040]

[0041] anode

[0042] In a heteroelectrolyte 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 impregnating the positive electrode electrolyte. The positive electrode mixture layer can be formed by coating a positive electrode slurry containing a positive electrode active material, a binder, a conductive agent, a solvent, etc. on a positive electrode current collector, followed by drying and rolling.

[0043] In an exemplary embodiment, the cathode electrolyte may include a lithium salt, a solvent, and optional additives. The cathode electrolyte may include a solvent or cathode film-forming material with poor reduction stability. The additives and / or solvents used in the cathode electrolyte may be the same as those used in the aforementioned polymer-based solid electrolyte.

[0044] Meanwhile, the positive and negative electrolytes may have different compositions, for example, the type and / or concentration of lithium salts may be different, and the preferred positive and negative electrolyte compositions may vary depending on the cell design and the functionality sought. For example, in the case of a Si-rich cell, an excess of a cyclic carbonate compound (e.g., FEC) must be added to continuously form a film that suppresses side reactions caused by cracks in the active material during charge and discharge. However, this has no functionality in the positive electrode and increases the resistance of the entire cell. In this case, an electrolyte composition with an excess of a 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.

[0045] In an exemplary embodiment, the lithium salt contained in the positive electrode electrolyte is Li as a cation. + , and 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 .

[0046] The above lithium salt may be used alone or in combination of two or more as needed. The lithium salt may be appropriately changed within a generally usable range, but in order to obtain an optimal effect of forming a film to prevent corrosion 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.

[0047] The above-mentioned positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used.

[0048] The above-mentioned 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 lithium and one or more metals such as cobalt, manganese, nickel or aluminum. More specifically, the lithium composite metal oxide may be a lithium-manganese oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt oxide (e.g., LiCoO2, etc.), a lithium-nickel oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese oxide (e.g., LiNi 1-Y Mn Y O2 (here, 0 <Y<1), LiMn 2-z Ni zO4 (where 0<Z<2), etc.), lithium-nickel-cobalt oxides (e.g., LiNi 1-Y1 Co Y1 O2 (here, 0 <Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo 1-Y2 Mn Y2 O2 (here, 0 <Y2<1), LiMn 2-z1 Co z1 O4 (wherein, 0<Z1<2) etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni p Co q Mn r1 )O2(wherein, 0<p<1, 0<q<1, 0<r1<1, p+q+r1=1) or Li(Ni p1 Co q1 Mn r2 )O4 (wherein, 0<p1<2, 0<q1<2, 0<r2<2, p1+q1+r2=2) etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M S2 )O2 (wherein, M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and p2, q2, r3 and s2 are atomic fractions of independent elements, respectively, 0<p2<1, 0<q2<1, 0<r3<1, 0<s2<1, p2+q2+r3+s2=1), etc.), and one or more compounds of these may be included.

[0049] Among these, the lithium composite metal oxides are LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (e.g., Li(Ni)) in that they can improve the capacity characteristics and stability of the battery. 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 Co0.2 )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 (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.) etc.

[0050] The above positive electrode active material may be included in an amount of 80 wt% to 99.5 wt%, specifically 85 wt% to 95 wt%, based on the total weight of the solid content in the positive electrode slurry.

[0051] When the content of the above positive electrode active material is less than 80 wt%, the energy density may decrease and the capacity may decrease.

[0052] The above binder is a component that assists in the bonding of the active material and the conductive material and the bonding to the current collector, and is typically added in an amount of 1 to 30 wt% based on the total weight of the solid content in the positive electrode slurry. It is added in an amount of 1 to 50 wt%, and more specifically, 3 to 15 wt%, based on the total weight of the solid content in the positive electrode slurry. If the binder is less than 1 wt%, the adhesive strength between the electrode active material and the current collector may become insufficient, and if it exceeds 50 wt%, the adhesive strength may improve, but the content of the electrode active material may decrease accordingly, which may lower the battery capacity.

[0053] Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluoroelastomer, and various copolymers.

[0054] In addition, the conductive material is a material that provides conductivity without causing chemical changes in the battery, and can be added in an amount of 1 to 20 wt% based on the total weight of the solid content in the positive electrode slurry.

[0055] Examples of such conductive materials include carbon powders such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powders such as natural graphite, artificial graphite, or graphite with highly developed crystal structures; conductive fibers such as carbon fibers or metal fibers; metal powders such as fluorocarbon, aluminum, or nickel powders; conductive whiskies such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. Currently, those commercially available under the names of acetylene black series conductive materials (manufactured by Chevron Chemical Company, Denka Black (manufactured by Denka Singapore Private Limited), or Gulf Oil Company), Ketjenblack, EC series (manufactured by Armak Company), Vulcan XC-72 (manufactured by Cabot Company), and Super-P (manufactured by Timcal) can also be used.

[0056] The solvent may include an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a desirable viscosity when including the positive electrode active material and optionally a binder and a conductive material. For example, the solvent may be included so that the solid concentration in the slurry including the positive electrode active material and optionally a binder and a conductive material is 10 wt% to 60 wt%, preferably 20 wt% to 50 wt%.

[0057]

[0058] cathode

[0059] In a heteroelectrolyte 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 impregnating the negative electrode mixture with a negative electrode electrolyte. The negative electrode mixture layer can be formed by coating a negative electrode slurry containing a negative electrode active material, a binder, a conductive agent, a solvent, etc. on a negative electrode current collector, followed by drying and rolling.

[0060] In an exemplary embodiment, the anolyte may include a lithium salt, a solvent, and optional additives. The anolyte may include a solvent or a cathode film-forming material with poor oxidation stability. The additives and / or solvents used in the anolyte may be the same as those used in the polymer-based solid electrolyte described above.

[0061] In an exemplary embodiment, the lithium salt contained in the negative electrolyte is Li as a cation. + , and 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 .

[0062] The above lithium salt may be used alone or in combination of two or more as needed. The lithium salt may be appropriately changed within a generally usable range, but in order to obtain an optimal effect of forming a film to prevent corrosion on the electrode surface, it may be included in the negative electrolyte at a concentration of 0.8 M to 2 M, specifically 0.8 M to 1.5 M.

[0063] The above negative electrode current collector may generally have a thickness of 3 to 500 μm. The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. may be used. In addition, similar to the positive electrode current collector, the bonding strength of the negative electrode active material may be strengthened by forming fine unevenness on the surface, and may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0064] In addition, the negative electrode active material may include at least one selected from the group consisting of lithium metal, a carbon material capable of reversibly intercalating / deintercalating lithium ions, a metal or an alloy of these metals and lithium, a metal composite oxide, a material capable of doping and dedoping lithium, and a transition metal oxide.

[0065] As the carbon material capable of reversibly intercalating / deintercalating the lithium ions, any carbon-based negative electrode active material commonly used in lithium-ion secondary batteries can be used without particular limitation, and representative examples thereof include crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon), hard carbon, mesophase pitch carbide, calcined coke, etc.

[0066] As the above metal or an alloy of these metals with 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 with lithium may be used.

[0067] The above metal composite oxides 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, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 로 이루어진 군에서 선택되는 것이 사용될 수 있다.

[0068] Materials capable of doping and dedoping the above lithium include Si, SiO x(0 < x < 2), Si-Y alloy (wherein 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 (wherein 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), and at least one of these may be mixed with SiO2 for use. The above element Y may be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, 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.

[0069] Examples of the above transition metal oxides include lithium-containing titanium composite oxide (LTO), vanadium oxide, and lithium vanadium oxide.

[0070] The above negative electrode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the solid content in the negative electrode slurry.

[0071] The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and is typically added in an amount of 1 to 30 wt% 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, fluororubber, and various copolymers thereof.

[0072] The above-mentioned conductive material may be the same material used in manufacturing the positive electrode, and may be added in an amount of 1 to 20 wt% based on the total weight of the solid content in the negative electrode slurry.

[0073] The solvent may include water or an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a desirable viscosity when including the negative electrode active material, and optionally a binder and a conductive material. For example, the concentration of the solid content including the negative electrode active material, and optionally a binder and a conductive material may be 50 wt% to 95 wt%, preferably 70 wt% to 90 wt%.

[0074] In an exemplary embodiment, the first gel polymer and the second gel polymer may be the same material or different materials. Meanwhile, the content of the first gel polymer of the positive electrolyte and the content of the second gel polymer of the negative electrolyte may be substantially the same or different from each other. That is, the content of the first gel polymer of the positive electrolyte may be greater or less than the content of the second gel polymer of the negative electrolyte.

[0075] In an exemplary embodiment, the separator may be in direct contact with the positive and negative electrodes. Specifically, an additional layer may not be provided between the separator and the positive electrode or between the separator and the negative electrode, and thus at least a portion of the separator may be in direct contact with the positive and negative electrodes. Accordingly, the heteroelectrolyte secondary battery according to an embodiment of the present invention may provide adhesive strength by curing the positive electrode / separator / negative electrode while being pressed, and thus may not require a separate adhesive material or lamination process.

[0076]

[0077] Method for manufacturing a heterogeneous electrolyte secondary battery

[0078] According to another embodiment of the present invention, a method for manufacturing a heteroelectrolyte secondary battery is provided, comprising the steps of: preparing a positive electrode and a negative electrode by impregnating a reserve positive electrode and a reserve negative electrode with a positive electrode electrolyte and a negative electrode electrolyte, respectively; impregnating a separator with 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.

[0079] The manufacturing method according to an embodiment of the present invention involves pre-impregnation of the electrode and separator followed by an assembly process, thereby enabling a reduction in the amount of electrolyte used with minimal electrolyte usage, thereby offering advantages in terms of safety and cost. Furthermore, with the exception of the electrode electrolyte impregnation and cross-linking processes, the current mass-production process can be utilized in the same manner, without the need for any special equipment additions or modifications.

[0080] First, the positive electrode and the negative electrode can be prepared by impregnating the reserve positive electrode and the reserve negative electrode with the positive electrode electrolyte and the negative electrode electrolyte, respectively. Specifically, the positive electrode electrolyte including the first gel polymer can be impregnated into the reserve positive electrode prepared by forming a positive electrode mixture layer on the positive electrode current collector, and the negative electrode electrolyte including the second gel polymer can be impregnated into the reserve negative electrode prepared by forming a negative electrode mixture layer on the negative electrode current collector. Such impregnation can be performed using a method commonly used in the art.

[0081] In an exemplary embodiment, the impregnation step may be performed 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 positive electrode after impregnation may be 0.1 to 10 wt%, and the content of the second gel polymer relative to the total weight of the negative electrode after impregnation may be 0.1 to 10 wt%.

[0082] Additionally, the separator may be impregnated with a polymer-based solid electrolyte, or the electrolyte layer may be prepared using a polymer-based solid electrolyte membrane. Specifically, the separator and polymer-based solid electrolyte may be the same as those described above, and may be impregnated in the same manner as the electrode. Such a separator can minimize resistance increase by applying a separator impregnated with a minimal amount of a high-content polymer-based solid electrolyte or a high-content gel polymer thin film.

[0083] Next, the positive electrode, the separator, and the negative electrode can be sequentially laminated and cured. For example, the positive electrode, the separator, and the negative electrode can be sequentially arranged to form an electrode assembly. Specifically, the electrode assembly can be a laminated structure having two types of electrodes, a positive electrode and a negative electrode, and an electrolyte layer as a separator, which is interposed between the electrodes or is interposed on the upper or lower side of one of the electrodes to mutually insulate the electrodes. The laminated structure is not limited to a variety of forms, such as a positive electrode and a negative electrode having a predetermined specification being laminated with a separator interposed therebetween, or being wound in the form of a jelly roll. A positive electrode tab and a negative electrode tab can be connected to the electrode assembly. Specifically, the positive electrode tab and the negative electrode tab are respectively connected to the positive electrode and the negative electrode of the electrode assembly, and can protrude to the outside of the secondary battery case to serve as a path through which electrons can move.

[0084] Thereafter, the laminated positive electrode, separator, and negative electrode can be cured, and specifically, the positive electrolyte impregnated in the positive electrode, the negative electrolyte impregnated in the negative electrode, and the polymer-based solid electrolyte of the separator can be cured. This curing step can be performed by a thermal curing process.

[0085] As described above, the gel polymer secondary battery according to the embodiment of the present invention can selectively transmit only lithium ions within the cell and maintain the isolation of heterogeneous electrolytes by applying a high-content polymer-based solid electrolyte to the separator to suppress the movement of large molecular weight substances between the positive and negative electrodes, thereby utilizing a polymer-based solid electrolyte-impregnated separator such as Li-Nafion, and by varying the composition of the positive and negative electrode electrolytes in a cell designed to transmit only lithium ions, solvents, salts, additives, etc. that have poor oxidation and reduction stability at a specific potential can be used without side reactions over a wide operating voltage range.

[0086] Figure 1 schematically illustrates a mechanism for inhibiting the movement of anions and additives between the positive and negative electrodes in a heteroelectrolyte secondary battery according to an embodiment of the present invention.

[0087] Figures 2 and 3 compare and illustrate the results of charge and discharge analysis of heterogeneous electrolyte secondary batteries according to Examples 1 and 2 of the present invention.

[0088] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0089]

[0090] Example 1: Cell with heterogeneous gel electrolyte application

[0091] A positive electrode electrolyte was prepared by dissolving 1 M LiPF6 in a solvent (ethylene carbonate (EC): propylene carbonate (PC) = 5:5 volume ratio) and adding 0.06 wt% of AIBN as a polymerization initiator, and an NCM 811 positive electrode was impregnated therein. In addition, a negative electrode electrolyte was prepared by dissolving 2 M LiFSI in a solvent (ethylene carbonate (EC): propylene carbonate (PC) = 5:5 volume ratio) and adding 0.06 wt% of AIBN as a polymerization initiator, and a graphite negative electrode was impregnated therein.

[0092] In addition, a polymer-based solid electrolyte composition was prepared by adding 20 wt% of Li-Nafion and 0.06 wt% of AIBN as a polymerization initiator to NMP solvent, and a PP separator was impregnated therein. After impregnation of the separator, vacuum drying was performed at 100°C for 12 hours to remove the NMP solvent.

[0093] The prepared materials were sequentially laminated in the order of anode / separator / cathode, pressed, and heat-cured at 60°C for 5 hours to manufacture a 'Set1' full cell.

[0094]

[0095] Example 2: Cell with heterogeneous gel electrolyte membrane application

[0096] A 'Set2' full cell was manufactured in the same manner as Example 1, except that a Li-Nafion membrane (Nafion membrane purchased from Sigma-aldrich and lithiated by reacting with a 1M LiOH solution) was used as the polymer-based solid electrolyte (Li-Nafion membrane: 13 μm, membrane: approximately 70 μm).

[0097]

[0098] Example 3: Cell with heterogeneous gel electrolyte application

[0099] A 'Set3' full cell was manufactured in the same manner as in Example 1, except that a PP separator was used without impregnating the polymer-based solid electrolyte into the composition.

[0100]

[0101] Experimental Example 1: Charge-Discharge Analysis

[0102] The charge-discharge efficiency of the secondary battery manufactured in Example 1-3 was evaluated, and the results are shown in Fig. 2. Specifically, the samples of Example 1-3 were each charged at a constant current of 0.1 C to 4.20 V, left for 30 minutes, and then discharged to 2.5 V at a constant current of 0.1 C to observe the charge-discharge characteristics in the first cycle.

[0103] In addition, the sample of Example 1-3 was charged and discharged twice at an initial rate of 0.1 C, and then charged and discharged three times each at 0.33 C. The charging and discharging were repeated, and the discharge capacity was measured at each cycle, which is shown in Fig. 3.

[0104] The PC will charge Li during the initial charging process. + In the form of Li-(PC)n coordinated with Li, it penetrates into the negative graphite lattice structure, causing structural destruction and exfoliation, resulting in capacity reduction. When 2M LiFSI is applied, Li +-The coordination number between PCs is reduced, so the performance degradation due to peeling is significantly reduced.

[0105] Referring to FIGS. 2 and 3, it was confirmed that in Example 1 (Set1), the movement of the electrolyte impregnated in the positive electrode through the separator was blocked, and in Example 2 (Set2), the movement through the heterogeneous gel electrolyte membrane was blocked. However, in the case of Example 2 (Set2), although the mutual movement of the electrolytes was blocked, due to the thick thickness of the membrane, in contrast, in Example 3 (Set3), the electrolyte impregnated in the positive electrode moved and mixed with the electrolyte impregnated in the negative electrode, showing a tendency for significant capacity and lifespan reduction. Through this, it was confirmed that the Li-Nafion or Li-Nafion membrane impregnated in the separator effectively blocks the movement of substances between the positive electrode and the negative electrode.

[0106] Therefore, the gel polymer secondary battery according to the present invention can maintain the isolation of the heterogeneous electrolyte between the positive and negative electrodes by applying a separator impregnated with Li-Nafion, and can have a wide operating voltage range and an effect of reducing the amount of electrolyte.

Claims

1. Anode impregnated with anode electrolyte; A cathode impregnated with a cathode electrolyte; and A separator interposed between the positive and negative electrodes and including a polymer-based solid electrolyte; A heteroelectrolyte secondary battery, 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.

2. In paragraph 1, A heteroelectrolyte secondary battery, wherein the separator is a separator impregnated with the polymer-based solid electrolyte or the polymer-based solid electrolyte membrane.

3. In paragraph 1, A heteroelectrolyte secondary battery, wherein the polymer resin comprises a perfluorosulfonic acid resin.

4. In paragraph 3, A heteroelectrolyte secondary battery, wherein the perfluorosulfonic acid resin is lithiated Nafion.

5. In paragraph 1, A heteroelectrolyte secondary battery, wherein the polymer resin content is 10 to 30 wt% based on the total weight of the separator.

6. In paragraph 1, A heteroelectrolyte secondary battery, wherein the polymer resin content is 15 to 25 wt% based on the total weight of the separator.

7. In paragraph 1, A heteroelectrolyte secondary battery, wherein the positive and negative electrolytes include at least one lithium salt selected from the group consisting of LiSCN, LiN(CN)2, LiClO4, LiBF4, LiAsF6, LiPF6, LiCF3SO3, LiC(CF3SO2)3, LiN(SO2C2F5)2, LiN(SO2CF3)2, LiN(SO2F)2, LiSbF6, LiPF3(CF2CF3)3, LiPF3(CF3)3, and LiB(C2O4)2.

8. In paragraph 7, A heteroelectrolyte secondary battery, wherein the positive and negative electrolytes contain different lithium salts.

9. In paragraph 7, A heteroelectrolyte secondary battery, wherein the positive electrode electrolyte contains a lithium salt at a concentration of 0.1 M to 2 M.

10. In paragraph 7, A heteroelectrolyte secondary battery, wherein the negative electrolyte contains a lithium salt at a concentration of 1 M to 3 M.

11. In paragraph 1, The above separator is lithium ion (Li + ) A heteroelectrolyte secondary battery having selective permeability.

12. In paragraph 1, A heteroelectrolyte secondary battery, wherein the separator is in direct contact with the positive and negative electrodes.

13. A step of preparing the anode and cathode by impregnating the reserve anode and reserve cathode with the anode electrolyte and cathode electrolyte, respectively; A step of impregnating a separator with a polymer-based solid electrolyte or preparing an electrolyte layer with a polymer-based solid electrolyte membrane; and A method for manufacturing a heteroelectrolyte secondary battery, comprising the step of sequentially stacking the positive electrode, the electrolyte layer, and the negative electrode.

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