Positive electrode slurry composition for rechargeable lithium battery, positive electrode and rechargeable lithium battery manufactured by using same

Abstract

The present invention relates to a positive electrode slurry composition for a rechargeable lithium battery, and a positive electrode and a rechargeable lithium battery manufactured using same. The positive electrode slurry composition for a rechargeable lithium battery comprises: a positive electrode active material; an additive; and a solvent, wherein the additive includes: a first additive including a styrene-butadiene-based structural unit and a thiol-based structural unit; and a second additive including an oxygen-containing heterocyclic compound.

Description

Anode slurry composition for lithium secondary batteries, anode manufactured using the same, and lithium secondary battery

[0001] The present invention relates to a positive electrode slurry composition for a lithium secondary battery, a positive electrode manufactured using the same, and a lithium secondary battery.

[0002]

[0003] Lithium secondary batteries are rechargeable and, compared to conventional lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and nickel-zinc batteries, have an energy density more than three times higher per unit weight and can be fast-charged. As a result, they are being commercialized for laptops, mobile phones, power tools, and electric bicycles, and research and development to further improve energy density is actively underway.

[0004] These lithium secondary batteries are used by injecting an electrolyte into an electrode assembly comprising a positive electrode containing a positive electrode active material capable of intercalating and deintercalating lithium, and a negative electrode containing a negative electrode active material capable of intercalating and deintercalating lithium.

[0005] However, regardless of the type of electrolyte, the surface structure of the anode may collapse as charging and discharging of the lithium secondary battery continues. Meanwhile, when using a solid electrolyte, the interfacial adhesion between the anode active material and the electrolyte may decrease.

[0006]

[0007] One embodiment is intended to suppress the collapse of the surface structure of the positive electrode during operation of a lithium secondary battery regardless of the type of electrolyte, and to improve the interfacial adhesion between the positive electrode active material and the electrolyte even when a solid electrolyte is used as the electrolyte, while optimizing the trade-off relationship between adhesion and ion conductivity.

[0008]

[0009] One embodiment provides a positive electrode slurry composition for a lithium secondary battery comprising a positive electrode active material, an additive, and a solvent, wherein the additive comprises a first additive comprising a styrene-butadiene-based structural unit and a thiol-based structural unit; and a second additive comprising a heterocyclic compound comprising oxygen (O).

[0010] Another embodiment provides a lithium secondary battery comprising the above electrolyte.

[0011]

[0012] A positive electrode slurry composition for a lithium secondary battery according to one embodiment can suppress the breakdown of the surface structure of the positive electrode during operation of the lithium secondary battery regardless of the type of electrolyte, and can improve the interfacial adhesion between the positive electrode active material and the electrolyte even when a solid electrolyte is used as the electrolyte.

[0013] Accordingly, by using the positive electrode slurry composition for a lithium secondary battery of one embodiment, the performance and safety of the lithium secondary battery can be improved regardless of the type of electrolyte.

[0014]

[0015] FIGS. 1 to 4 are schematic diagrams illustrating a lithium secondary battery according to one embodiment.

[0016]

[0017] Unless otherwise specifically stated in this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between.

[0018] Unless otherwise specified in this specification, a singular form may also include a plural form. Additionally, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B."

[0019] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0020] Unless specifically stated in this specification, "substitution" means that at least one hydrogen atom in a compound is a halogen atom (F, Cl, Br, I), a hydroxyl group, a C1 to C20 alkoxy group, a nitro group, a cyano group, an amine group, an imino group, an azido group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamyl group, a thiol group, an ester group, an ether group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C30 aryl group, a C3 to C20 cycloalkyl group, a C3 to C20 cycloalkenyl group, a C3 to C20 cycloalkynyl group, a C2 to C20 heterocycloalkyl group, a C2 to C20 heterocycloalkenyl group, C2 to It means substituted with a C20 heterocycloalkynyl group or a combination thereof.

[0021] Unless otherwise specifically stated in this specification, "heterocycloalkyl group," "heterocycloalkenyl group," "heterocycloalkynyl group," and "heterocycloalkylene group" each mean that at least one heteroatom of N, O, S, or P is present in a ring compound of cycloalkyl, cycloalkenyl, cycloalkynyl, and cycloalkylene.

[0022] Unless otherwise defined in the chemical formulas within this specification, if a chemical bond is not drawn at a position where a chemical bond should be drawn, it means that a hydrogen atom is bonded at said position.

[0023]

[0024] (Cathode slurry composition for lithium secondary batteries)

[0025] One embodiment provides a positive electrode slurry composition for a lithium secondary battery comprising a positive electrode active material, an additive, and a solvent, wherein the additive comprises a first additive comprising a styrene-butadiene-based structural unit and a thiol-based structural unit; and a second additive comprising a heterocyclic compound comprising oxygen (O).

[0026] In general, styrene-butadiene rubber (SBR) is known to be nonpolar, and its tackiness is in a trade-off relationship with ionic conductivity.

[0027] One embodiment presents a first additive comprising a styrene-butadiene-based structural unit and a thiol-based structural unit.

[0028] Since the styrene-butadiene-based structural unit is nonpolar but the thiol-based structural unit is polar, it is easy to control the polarity of the first additive by adjusting the content of each structural unit. Accordingly, the first additive may have improved adhesive strength compared to styrene-butadiene rubber while ensuring ion conductivity within an appropriate range.

[0029] Meanwhile, one embodiment presents a third additive comprising a heterocyclic compound containing oxygen (O).

[0030] The above-mentioned heterocyclic compound containing oxygen (O) can form a polyacetal structure through a ring-opening reaction. Accordingly, the second additive can suppress structural collapse of the positive electrode during operation of the lithium secondary battery regardless of the type of electrolyte, and can improve interfacial adhesion between the positive electrode active material and the electrolyte even when a solid electrolyte is used as the electrolyte.

[0031] Accordingly, a positive electrode slurry composition for a lithium secondary battery according to one embodiment, comprising the first additive and the second additive, can suppress the collapse of the surface structure of the positive electrode during operation of the lithium secondary battery regardless of the type of electrolyte, and can optimize the trade-off relationship between adhesion and ion conductivity while improving the interfacial adhesion between the positive electrode active material and the electrolyte even when a solid electrolyte is used as the electrolyte.

[0032] Accordingly, by using the positive electrode slurry composition for a lithium secondary battery of one embodiment, the performance and safety of the lithium secondary battery can be improved regardless of the type of electrolyte.

[0033]

[0034] Hereinafter, a positive electrode slurry composition for a lithium secondary battery according to one embodiment will be described in detail.

[0035]

[0036] First additive

[0037] The first additive above may be a block copolymer represented by the following chemical formula 1:

[0038] [Chemical Formula 1]

[0039] ABA

[0040] In the above chemical formula 1, A may be the same or different and each independently represent a structural unit represented by the following chemical formula 2-1; and B may be a structural unit represented by the following chemical formula 2-2.

[0041] [Chemical Formula 2-1]

[0042]

[0043] In the above chemical formula 2-1, R 1 is the same or different and may be H, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms; n may be an integer from 1 to 6.

[0044] For example, R 1All can be H, and n can be an integer of 6.

[0045] [Chemical Formula 2-2]

[0046]

[0047] In the above chemical formula 2-2, R 2 may be a substituent represented by the following chemical formulas 3-1, 3-2, 3-3, 3-4, or 3-5.

[0048] [Chemical Formula 3-1]

[0049]

[0050] In the above chemical formula 3-1, L 1 ☐ may be a substituted or unsubstituted alkylene group having 1 to 30 carbon atoms; R 3 ≡ may be OH, SO3M, or a substituent represented by the following chemical formula 4-1 or 4-2; where M may be Li, Na, or K.

[0051] For example, L 1 ☐ may be a substituted or unsubstituted alkylene group having 1 to 13 carbon atoms; R 3 It may be OH, SO3Na, or a substituent represented by the following chemical formula 4-1 or 4-2.

[0052] [Chemical Formula 3-2]

[0053]

[0054] In the above chemical formula 3-2, L 2 may be a substituted or unsubstituted alkylene group having 1 to 30 carbon atoms; L 3 The groups may be identical or different, and each may independently be a single bond, or a substituted or unsubstituted alkylene group having 1 to 30 carbon atoms.

[0055] For example, L 2 can be CH2 and; L 3 One of them may be a single bond and the other may be CH2.

[0056] [Chemical Formula 5-1]

[0057]

[0058] In the above chemical formula 5-1, R 4 ≡ may be H, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms.

[0059] For example, R 4 can be H.

[0060] [Chemical Formula 5-2]

[0061]

[0062] In the above chemical formula 5-2, R 5 ≡ may be H, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms.

[0063] For example, R 5 It could be CH3.

[0064]

[0065] The above A may be a structural unit represented by the following chemical formula 2-1-1:

[0066] [Chemical Formula 2-1]

[0067]

[0068]

[0069] The above B may be a structural unit represented by any one of the following chemical formulas 2-2-1 to 2-2-5:

[0070] [Chemical Formula 2-2-1]

[0071]

[0072] [Chemical Formula 2-2-2]

[0073]

[0074] [Chemical Formula 2-2-3]

[0075]

[0076] [Chemical Formula 2-2-4]

[0077]

[0078] [Chemical Formula 2-2-5]

[0079]

[0080] In the above chemical formulas 2-2-1 to 2-2-5, L 4 is an alkyl group having 1 to 11 carbon atoms.

[0081]

[0082] The first additive above may be a compound selected from the following chemical formulas 6-1 to 6-5.

[0083] [Chemical Formula 6-1]

[0084]

[0085] [Chemical Formula 6-2]

[0086]

[0087] [Chemical Formula 6-3]

[0088]

[0089] [Chemical Formula 6-4]

[0090]

[0091] [Chemical Formula 6-5]

[0092]

[0093]

[0094] In the above chemical formulas 6-1 to 6-5, a may be the same or different and may be an integer from 1 to 100; b may be an integer from 1 to 100; and L 4 can be an alkyl group having 1 to 11 carbon atoms.

[0095]

[0096] In the first additive above, the content of the thiol-based structural unit may be 2 to 40 weight%, 2 to 20 weight%, or 2 to 10 weight% with respect to the total amount of 100 weight% of the styrene-butadiene-based structural unit and the thiol-based structural unit.

[0097] The weight-average molecular weight (Mw) of the first additive measured by the GPC method may be 10,000 to 250,000 g / mol.

[0098]

[0099] Second additive

[0100] The above second additive can be represented by the following chemical formula 7:

[0101] [Chemical Formula 7]

[0102]

[0103] In the above chemical formula 7, X 1 is identical or different, and is O or S; X 1 At least one of them can be O; R 6 The groups may be identical or different, and each may independently be H, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms.

[0104] For example, X 1 All can be O and; R 6 The groups may be identical or different, and each may independently be H, or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms.

[0105]

[0106] The second additive above may be a compound selected from the following chemical formulas 8-1 and 8-2:

[0107] [Chemical Formula 8-1]

[0108]

[0109] [Chemical Formula 8-2]

[0110]

[0111] In the above chemical formula 8-2, R 7 The groups may be identical or different, and each may independently be H, or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms.

[0112]

[0113] Content of additives in the anode slurry composition

[0114] With respect to 100 weight% of the total solid content of the anode slurry composition, the content of the first additive may be 0.1 to 5 weight%, 0.1 to 3 weight%, or 0.1 to 1 weight%.

[0115] With respect to 100 weight% of the total solid content of the anode slurry composition, the content of the second additive may be 0.1 to 5 weight%, 0.1 to 3 weight%, or 0.1 to 1 weight%.

[0116] The content ratio of the first additive and the second additive in the anode slurry composition may be 10:1 to 1:10, 5:1 to 1:5, or 3:1 to 1:3 by weight.

[0117] When the above ranges are satisfied, the effects of the first additive and the second additive can be harmonized.

[0118]

[0119] positive electrode active material

[0120] As a positive electrode active material, a compound capable of reversible intercalation and deintercalation of lithium (a lithated intercalation compound) may be used. Specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0121] The above composite oxide may be a lithium transition metal composite oxide, and specific examples include a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, a cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0122] As an example, a compound represented by any one of the following chemical formulas may be used. Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Lia Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0123] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al, or a combination thereof.

[0124] The positive electrode active material may include, for example, a lithium nickel-based oxide represented by the following chemical formula 11, a lithium cobalt-based oxide represented by the following chemical formula 12, a lithium iron phosphate-based compound represented by the following chemical formula 13, a cobalt-free lithium nickel-manganese-based oxide represented by the following chemical formula 14, or a combination thereof.

[0125] [Chemical Formula 11]

[0126] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0127] In the above chemical formula 11, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1, and M 1 and M 2Each is independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0128] In the above chemical formula 11, 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.4, or 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2.

[0129] [Chemical Formula 12]

[0130] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0131] In the above chemical formula 12, 0.9≤a2≤1.8, 0.7≤x2≤1, 0≤y2≤0.3, 0.9≤x2+y2≤1.1, and 0≤b2≤0.1, and M 3 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0132] [Chemical Formula 13]

[0133] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0134] In the above chemical formula 13, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.95, and 0≤b3≤0.1, and M 4is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0135] [Chemical Formula 14]

[0136] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0137] In the above chemical formula 14, 0.9≤a4≤1.8, 0.8≤x4<1, 0 <y4≤0.2, 0≤z4≤0.2, 0.9≤x4+y4+z4≤1.1, 및 0≤b4≤0.1이고 M 5 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0138] For example, the above-mentioned positive electrode active material may be a high-nickel positive electrode active material in which the nickel content relative to 100 mol% of the metal excluding lithium in the lithium transition metal composite oxide is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less. The high-nickel positive electrode active material can achieve high capacity and can be applied to high-capacity, high-density lithium secondary batteries.

[0139]

[0140] Binder and conductive material

[0141] The above anode slurry composition may further include a binder, a conductive material, or a combination thereof.

[0142] The above binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples of binders include, but are not limited to, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0143] The above conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube; metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0144]

[0145] menstruum

[0146] The above solvent may be N-Methyl-2-pyrrolidone (NMP), p-xylene, tetralin, octyl acetate, hexyl butyrate, or a combination thereof.

[0147] The content of the solvent may be 10 to 50 weight%, 10 to 40 weight%, or 10 to 30 weight% with respect to the total amount of 100 weight% of the anode slurry composition.

[0148]

[0149] (anode)

[0150] Another embodiment provides a positive electrode for a lithium secondary battery comprising a positive current collector and a positive active material layer located on at least one surface of the positive current collector; wherein the positive active material layer comprises a positive active material and an additive, the additive comprising a first additive comprising a copolymer of a styrene-butadiene-based polymer and a thiol-based monomer; and a second additive comprising a heterocyclic compound comprising oxygen (O).

[0151] The above-mentioned positive active material layer may be one from which only the solvent has been removed from the positive slurry composition of the aforementioned embodiment.

[0152]

[0153] Accordingly, descriptions that overlap with the previously mentioned embodiment are omitted, and the positive electrode of the embodiment is described in detail.

[0154]

[0155] anode

[0156] A positive electrode for a lithium secondary battery may include a current collector and a positive electrode active material layer formed on the current collector.

[0157] The content of the above positive active material may be 90% to 99.5% by weight with respect to 100% by weight of the positive active material layer. With respect to 100% by weight of the above positive active material layer, the content of the first additive may be 0.1% to 5% by weight, 0.1% to 3% by weight, or 0.1% to 1% by weight.

[0158] With respect to 100 weight% of the positive active material layer, the content of the second additive may be 0.1 to 5 weight%, 0.1 to 3 weight%, or 0.1 to 1 weight%.

[0159] The thickness of the above positive active material layer may be 10 to 200 μm.

[0160]

[0161] In one embodiment, the positive active material layer may further include a binder and a conductive material. In this case, the content of the binder and the conductive material may each be 0.5% to 5% by weight with respect to 100% by weight of the positive active material layer.

[0162]

[0163] Al may be used as the current collector mentioned above, but is not limited thereto.

[0164]

[0165] (Lithium secondary battery)

[0166] Another embodiment provides a lithium secondary battery comprising a positive electrode; a negative electrode; and an electrolyte of the above-described embodiment.

[0167]

[0168] This means that since a positive electrode is manufactured using the positive electrode slurry composition for a lithium secondary battery of the above-described embodiment, the performance and safety of the battery may be improved regardless of the type of electrolyte.

[0169] The above lithium secondary battery may be a lithium-ion battery, a solid-state battery, or a lithium-sulfur battery.

[0170]

[0171] Accordingly, descriptions that overlap with the previously mentioned embodiment are omitted, and the lithium secondary battery of the embodiment is described in detail.

[0172]

[0173] cathode active material

[0174] The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0175] A material capable of reversibly intercalating / deintercalating the above lithium ions may be a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0176] As the above lithium metal alloy, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

[0177] As a material capable of doping and undoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The above Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x ≤ 2), a Si-Q alloy (wherein Q is selected from alkali metals, alkaline earth metals, group 13 elements, group 14 elements (excluding Si), group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The above Sn-based negative electrode active material may be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0178] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, it may include a secondary particle (core) assembled from silicon primary particles and an amorphous carbon coating layer (shell) located on the surface of the secondary particle. The amorphous carbon may also be located between the silicon primary particles, so that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0179] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core.

[0180] The above Si-based or Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0181]

[0182] cathode

[0183] A negative electrode for a lithium secondary battery comprises a current collector and a negative electrode active material layer located on the current collector. The negative electrode active material layer comprises a negative electrode active material and may further comprise a binder and / or a conductive material.

[0184] For example, the negative electrode active material layer may comprise 90% to 99% by weight of negative electrode active material, 0.5% to 5% by weight of binder, and 0% to 5% by weight of conductive material.

[0185] The above binder serves to effectively bond the negative electrode active material particles to each other and also to effectively bond the negative electrode active material to the current collector. As the binder, a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof may be used.

[0186] Examples of the above-mentioned non-aqueous binders include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyimide, or combinations thereof.

[0187] The above-mentioned water-based binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0188] When a water-based binder is used as the above-mentioned cathode binder, a cellulose-based compound capable of imparting viscosity may be further included. As this cellulose-based compound, one or more types such as carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof may be mixed and used. Na, K, or Li may be used as the alkali metal.

[0189] The above dry binder is a polymer material capable of fiberization, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0190] The above conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjenblack, carbon fiber, carbon nanofiber, carbon nanotube; metal-based materials in the form of metal powder or metal fibers including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0191] As the above-mentioned cathode current collector, a material selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof may be used.

[0192]

[0193] electrolyte

[0194] The electrolyte for lithium secondary batteries contains a non-aqueous organic solvent and a lithium salt.

[0195] The above-mentioned non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0196] The above-mentioned non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof.

[0197] The above carbonate-based solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. As ester-based solvents, methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methylpropionate, ethylpropionate, decanolide, ν-butyrolactone, mevalonolactone, valerolactone, caprolactone, etc. As ether-based solvents, dibutyl ether, tetraglame, diglame, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. may be used. Additionally, as ketone-based solvents, cyclohexanone, etc. may be used. As alcohol-based solvents, ethyl alcohol, isopropyl alcohol, etc. may be used, and as aprotic solvents, nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane, 1,4-dioxolane; sulfolanes, etc. may be used.

[0198] The above-mentioned non-aqueous organic solvent can be used alone or in a mixture of two or more types.

[0199] In addition, when using a carbonate-based solvent, a mixture of cyclic carbonates and chain carbonates can be used, and the cyclic carbonates and chain carbonates can be mixed in a volume ratio of 1:1 to 1:9.

[0200] The above electrolyte may further include vinyl ethyl carbonate, vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, or a combination thereof as an additive.

[0201] The above lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions within the battery, enabling the basic operation of a lithium secondary battery and facilitating the movement of lithium ions between the anode and cathode. Representative examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 It may include one or more selected from SO2)(x and y are integers from 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluorobis(oxalate)phosphate (LiDFOB), and lithium bis(oxalate)borate (LiBOB).

[0202]

[0203] solid electrolyte

[0204] The above solid electrolyte may be an inorganic solid electrolyte, such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a halide-based solid electrolyte, or a solid polymer electrolyte.

[0205] Sulfide-based solid electrolytes include, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element, e.g., I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z m S n (m and n are integers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are integers, and M is P, Si, Ge, B, Al, Ga or In), or may include a combination thereof.

[0206] Such sulfide-based solid electrolytes can be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10 or 50:50 to 80:20 and optionally heat-treating. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be manufactured. Additionally, ionic conductivity may be further improved by including other components such as SiS2, GeS2, B2S3, etc.

[0207] Mechanical milling or the solution method can be applied as mixing methods for sulfur-containing raw materials to manufacture sulfide-based solid electrolytes. Mechanical milling is a method in which starting materials are placed in a reactor and vigorously stirred with a ball mill or similar device to finely pulverize and mix the starting materials. When using the solution method, starting materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, if heat treatment is performed after mixing, the crystals of the solid electrolyte can become more robust and the ionic conductivity can be improved. For example, a sulfide-based solid electrolyte can be manufactured by mixing sulfur-containing raw materials and heat-treating them two or more times; in this case, a robust sulfide-based solid electrolyte with high ionic conductivity can be produced.

[0208] For example, the sulfide-based solid electrolyte particles may include an argyrodite-type sulfide. The argyrodite-type sulfide is, for example, Li a M b P c S d A e It can be expressed by the chemical formula (where a, b, c, d, and e are all between 0 and 12, M is a metal excluding Li or a combination of multiple metals excluding Li, and A is F, Cl, Br, or I), and as a specific example, Li 7-x PS 6-x A x It can be expressed by the chemical formula (where x is 0.2 or greater and 1.8 or less, and A is F, Cl, Br, or I). Specifically, the azirodite-type sulfide is Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0209] Sulfide-based solid electrolyte particles containing such azirodite-type sulfides have an ionic conductivity of 10 at room temperature, which is the ionic conductivity of a typical liquid electrolyte. -4 to 10 -2 It has high ionic conductivity close to the S / cm range and can form a tight bond between the positive active material and the solid electrolyte without causing a decrease in ionic conductivity, and furthermore, can form a tight interface between the electrode layer and the solid electrolyte layer. An all-solid-state battery including this can improve battery performance such as rate characteristics, Coulomb efficiency, and lifespan characteristics.

[0210] An azirodite-type sulfide-based solid electrolyte can be prepared by mixing, for example, lithium sulfide and phosphorus sulfide, and optionally lithium halide. After mixing these, heat treatment may be performed. The heat treatment may include, for example, two or more heat treatment steps.

[0211] According to one embodiment, the average particle size (D50) of the sulfide-based solid electrolyte particles may be 5.0 μm or less, for example, 0.1 μm to 5.0 μm, 0.1 μm to 4.0 μm, 0.1 μm to 3.0 μm, 0.5 μm to 2.0 μm, or 0.1 μm to 1.5 μm. Alternatively, depending on the location or purpose of use, the sulfide-based solid electrolyte particles may be small particles having an average particle size (D50) of 0.1 μm to 1.0 μm, or large particles having an average particle size (D50) of 1.5 μm to 5.0 μm. Sulfide-based solid electrolyte particles within this particle size range can effectively penetrate between solid particles within the battery, and have excellent contact with the electrode active material and connectivity between solid electrolyte particles. The average particle size of the sulfide-based solid electrolyte particles may be measured using a microscopic image, for example, by measuring the size of about 20 particles in a scanning electron microscope image to obtain the particle size distribution and calculating D50 from it.

[0212] The above oxide-based inorganic solid electrolyte is, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Lithium Phosphate (Li3PO4), Lithium Titanium Phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate(Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr; x is an integer from 1 to 10), or may include a combination thereof.

[0213] The above halide-based solid electrolyte may include a Li element, an M element (M is a metal other than Li), and an X element (X is a halogen). Examples of X include F, Cl, Br, and I. In particular, for the halide-based solid electrolyte, at least one of Br and Cl is suitable as X. Additionally, examples of M include metal elements such as Sc, Y, B, Al, Ga, and In.

[0214] The composition of the above halide-based solid electrolyte is not particularly limited, but Li 6-3a M a Br b Cl c (In the formula, M is a metal other than Li, and 0 <a<2, 0≤b≤6, 0≤c≤6, b+c=6)로 표현될 수 있다. 이때, 상기 a는 0.75 이상일 수 있고, 1 이상일 수 있고, a는, 1.5 이하일 수 있다. 상기 b는 1 이상일 수 있고, 2 이상일 수 있다. 또한, 상기 c는, 3 이상일 수 있고, 4 이상일 수도 있다. 상기 할라이드계 고체 전해질의 구체적인 예로는 Li3YBr6, Li3YCl6또는 Li3YBr2Cl4를 들 수 있다.

[0215] The above solid polymer electrolyte is, for example, polyethylene oxide, poly(diallyldimethylammonium)trifluoromethanesulfonylimide (poly(diallyldimethylammonium)TFSI), Cu3N, Li3N, LiPON, Li3PO 4· Li2S · SiS2, Li2S · GeS2.Ga2S3, Li2O · 11Al2O3, Na2O · 11Al2O3, (Na,Li) 1+x Ti 2-x Al x (PO4)3(0.1≤x≤0.9), Li 1+x Hf 2-x Al x (PO4)3(0.1≤x≤0.9), Na3Zr2Si2PO12 , Li3Zr2Si2PO 12 , Na5ZrP3O 12 , Na5TiP3O 12 , Na3Fe2P3O 12 , Na4NbP3O 12 , Na-silicate, Li 0.3 La 0.5 TiO3, Na5MSi4O 12 (M is a rare earth element such as Nd, Gd, or Dy) Li5ZrP3O 12 , Li5TiP3O 12 , Li3Fe2P3O 12 , Li4NbP3O 12 , Li 1+x (M,Al,Ga) x (Ge 1-y Ti y ) 2-x (PO4)3(x≤0.8, 0≤y≤1.0, M is Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), Li 1+x+y Q x Ti 2-x Si y P 3-y O 12 (0 <x≤0.4, 0<y≤0.6, Q는 Al 또는 Ga), Li6BaLa2Ta2O 12 , Li7La3Zr2O 12 , Li5La3Nb2O 12 , Li5La3M2O 12 (M is Nb, Ta) and Li 7+x A x La 3-x Zr2O 12 (0 <x<3, A는 Zn) 중에서 선택된 하나 이상을 포함할 수 있다.

[0216] The content of the solid electrolyte in the anode for the all-solid-state battery may be 0.5 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%. This is the content relative to the total weight of the components in the anode, and specifically, it can be said to be the content relative to the total weight of the anode active material layer.

[0217] In one embodiment, the positive active material layer may comprise, with respect to 100 weight% of the positive active material layer, 50 weight% to 99.35 weight% of a positive active material, 0.5 weight% to 35 weight% of a sulfide-based solid electrolyte, 0.1 weight% to 10 weight% of a fluorine-based resin binder, and 0.05 weight% to 5 weight% of vanadium oxide. When such content ranges are satisfied, the positive electrode for an all-solid-state secondary battery can achieve high capacity and high ionic conductivity while maintaining high adhesion, and the viscosity of the positive electrode composition can be maintained at an appropriate level, thereby improving processability.

[0218]

[0219] separator

[0220] Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. As such a separator, polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more layers thereof may be used, and of course, mixed multilayer films such as polyethylene / polypropylene two-layer separators, polyethylene / polypropylene / polyethylene three-layer separators, and polypropylene / polyethylene / polypropylene three-layer separators may be used.

[0221] The above separator may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0222] The porous substrate may be a polymer membrane formed from any one of the following: polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyacetal; polyamide; polyimide; polycarbonate; polyetherketone; polyaryletherketone; polyetherimide; polyamideimide; polybenzimidazole; polyethersulfone; polyphenylene oxide; cyclic olefin copolymer; polyphenylene sulfide; polyethylene naphthalate; glass fiber; Teflon; and polytetrafluoroethylene, or a copolymer or mixture of two or more of these.

[0223] The above organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0224] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include, but is not limited to, inorganic particles selected from SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0225] The above organic and inorganic materials may exist mixed in a single coating layer, or may exist in a stacked form with a coating layer containing organic materials and a coating layer containing inorganic materials.

[0226]

[0227] lithium secondary battery

[0228] Lithium secondary batteries can be classified into cylindrical, prismatic, pouch, coin, etc., depending on their shape. FIGS. 1 to 4 are schematic diagrams illustrating a lithium secondary battery according to one embodiment, where FIG. 1 is a cylindrical battery, FIG. 2 is a prismatic battery, and FIGS. 3 and 4 are pouch-type batteries. Referring to FIGS. 1 to 4, the lithium secondary battery (100) may include an electrode assembly (40) having a separator (30) interposed between a positive electrode (10) and a negative electrode (20), and a case (50) in which the electrode assembly (40) is housed. The positive electrode (10), the negative electrode (20), and the separator (30) may be impregnated with an electrolyte (not shown). The lithium secondary battery (100) may include a sealing member (60) that seals the case (50) as in FIG. 1. In addition, in FIG. 2, the lithium secondary battery (100) may include a positive lead tab (11) and a positive terminal (12), a negative lead tab (21) and a negative terminal (22). As shown in FIG. 3 and FIG. 4, the lithium secondary battery (100) may include an electrode tab (70), namely a positive tab (71) and a negative tab (72), which serve as an electrical path to guide the current formed in the electrode assembly (40) to the outside.

[0229]

[0230] lithium-sulfur battery

[0231] A lithium-sulfur battery is largely composed of a positive electrode, a solid electrolyte, and a negative electrode. At this time, the solid electrolyte and the negative electrode are as described above. The positive electrode consists of a positive active material, a solid electrolyte, a binder, and a conductive material. Li2S or LiMoS2 is used as the positive active material, with a content of 20 wt% to 80 wt%. Carbon nanotubes, LiI, or CaI2 are used as the binder, with a content of 5 wt% to 30 wt%. The content of the solid electrolyte is 10 wt% to 50 wt%. The type of binder is as described above, and the content is 0.3 wt% to 5 wt%.

[0232]

[0233] A lithium secondary battery according to one embodiment of the present invention may be applied to automobiles, mobile phones, and / or various types of electric devices, etc., but the present invention is not limited thereto.

[0234]

[0235] Examples and comparative examples of the present invention are described below. However, the following examples are merely one example of the present invention, and the present invention is not limited to the following examples.

[0236]

[0237] Example 1-1

[0238] (1) Preparation of a first additive (Mw: 30,000 g / mol) of the ABA structure comprising a structural unit (A) represented by 2-1-1 below and a structural unit (B) represented by the chemical formula 2-2-1 below

[0239] After dissolving SBS (styrene-butadiene-styrene) copolymer in p-xylene, 3-mercaptopropionic acid and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, which is an initiator, are added and reacted, and then purification and drying processes are performed to prepare a first additive of the ABA structure comprising a structural unit (A) represented by 2-1-1 below and a structural unit (B) represented by the chemical formula 2-2-1 below.

[0240] [Chemical Formula 2-1]

[0241]

[0242] [Chemical Formula 2-2-1]

[0243]

[0244] (L 4 is CH2, and the thiol structural unit content is 4 wt%)

[0245]

[0246] (2) Preparation of positive electrode active material slurry

[0247] LiNi as a positive electrode active material 0.91 Co 0.05 Al 0.04 O2; carbon black as a conductive material, polyvinylidene fluoride (PVDF) as a binder, and a first additive represented by the above chemical formula 6-1 and a second additive represented by the following chemical formula 8-1 as additives were mixed in a weight ratio of 96:1.5:2:0.3:0.2 (weight ratio of the first additive and the second additive = 3:2), and then dispersed in NMP to prepare 78 weight% of an anode slurry composition.

[0248] [Chemical Formula 8-1]

[0249]

[0250]

[0251] The above anode slurry composition was coated onto an Al foil with a thickness of 10 μm, dried at 100°C, and then pressed to form an anode active material layer (thickness: 50 μm).

[0252]

[0253] A cathode slurry was prepared by adding additives to a water solvent in which synthetic graphite as a cathode active material, styrene-butadiene rubber (SBR) as a binder, and carboxymethylcellulose (CMC) as a thickener were mixed in a weight ratio of 97.4:1.7:0.9, respectively. The cathode slurry composition was coated onto a 10 μm thick Cu foil, dried at 120°C, and then pressed to form a cathode active material layer (thickness: 40 μm).

[0254] An electrolyte was prepared by adding a lithium salt (LiPF6) to a carbonate-based solvent mixed with ethylene carbonate (EC):propylene carbonate (PC):ethyl propionate (EP):propyl propionate (PP) in a volume ratio of 10:15:30:45 to a concentration of 1.3 M.

[0255]

[0256] (2) Manufacturing of lithium secondary batteries

[0257] An electrode assembly was manufactured by assembling a polyethylene separator with a thickness of 10 μm between the two anodes, and after housing the electrode assembly in a case, the electrolyte was injected to manufacture a lithium secondary battery.

[0258]

[0259] Examples 1-2

[0260] (1) Preparation of a first additive (Mw: 30,000 g / mol) of the ABA structure comprising a structural unit (A) represented by 2-1-1 and a structural unit (B) represented by the following chemical formula 2-2-2

[0261] A first additive of the ABA structure was prepared in the same manner as in Example 1-1, except that sodium 3-mercapto-1-propanesulfonate was used instead of 3-mercaptopropionic acid, comprising a structural unit (A) represented by 2-1-1 below and a structural unit (B) represented by the following chemical formula 2-2-2.

[0262] [Chemical Formula 2-1]

[0263]

[0264] [Chemical Formula 2-2-2]

[0265]

[0266] (However, the thiol-based structural unit content is 4 wt%)

[0267]

[0268] (2) Manufacturing of positive electrode active material slurry and lithium secondary battery

[0269] The positive electrode active material slurry, positive electrode, and lithium secondary battery of Example 1-2 were prepared in the same manner as in Example 1, except that a first additive having an ABA structure including the structural unit (A) represented by 2-1-1 and the structural unit (B) represented by the chemical formula 2-2-2 was used.

[0270]

[0271] Examples 1-3

[0272] (1) Preparation of a first additive (Mw: 30,000 g / mol) of the ABA structure comprising a structural unit (A) represented by 2-1-1 below and a structural unit (B) represented by the chemical formula 2-2-3 below

[0273] A first additive of the ABA structure was prepared in the same manner as the preparation of Chemical Formula 6-1, except that 3-mercapto-1,2,4-triazole was used instead of 3-mercaptopropionic acid, comprising a structural unit (A) represented by Chemical Formula 2-1-1 below and a structural unit (B) represented by Chemical Formula 2-2-3 below.

[0274] [Chemical Formula 2-1]

[0275]

[0276] [Chemical Formula 2-2-3]

[0277]

[0278] (However, the thiol-based structural unit content is 4 wt%)

[0279]

[0280] (2) Manufacturing of positive electrode active material slurry and lithium secondary battery

[0281] The positive electrode active material slurry, positive electrode, and lithium secondary battery of Example 1-3 were prepared in the same manner as in Example 1, except that a first additive having an ABA structure including the structural unit (A) represented by 2-1-1 and the structural unit (B) represented by the chemical formula 2-2-3 was used.

[0282]

[0283] Examples 1-4

[0284] (1) Preparation of a first additive (Mw: 30,000 g / mol) of the ABA structure comprising a structural unit (A) represented by 2-1-1 below and a structural unit (B) represented by the chemical formula 2-2-4 below

[0285] A first additive of the ABA structure was prepared in the same manner as in Example 1, except that 3-mercapto-4-methyl-4H-1,2,4-triazole was used instead of 3-mercaptopropionic acid, comprising a structural unit (A) represented by 2-1-1 and a structural unit (B) represented by the following chemical formula 2-2-4.

[0286] [Chemical Formula 2-1]

[0287]

[0288] [Chemical Formula 2-2-4]

[0289]

[0290] (However, the thiol-based structural unit content is 4 wt%)

[0291]

[0292] (2) Manufacturing of positive electrode active material slurry and lithium secondary battery

[0293] The positive electrode active material slurry, positive electrode, and lithium secondary battery of Example 1-4 were prepared in the same manner as in Example 1, except that a first additive having an ABA structure including the structural unit (A) represented by 2-1-1 and the structural unit (B) represented by the chemical formula 2-2-4 was used.

[0294]

[0295] Examples 1-5

[0296] (1) Preparation of a first additive (Mw: 30000 g / mol) of the ABA structure comprising a structural unit (A) represented by 2-1-1 and a structural unit (B) represented by the following chemical formula 2-2-5

[0297] A first additive of the ABA structure was prepared in the same manner as in Example 1, except that 3-mercapto-1,2-propanediol was used instead of 3-mercaptopropionic acid, comprising a structural unit (A) represented by 2-1-1 and a structural unit (B) represented by the following chemical formula 2-2-5.

[0298] [Chemical Formula 2-1]

[0299]

[0300] [Chemical Formula 2-2-5]

[0301]

[0302] (However, the thiol-based structural unit content is 4 wt%)

[0303]

[0304] (2) Manufacturing of positive electrode active material slurry and lithium secondary battery

[0305] The positive electrode active material slurry, positive electrode, and lithium secondary battery of Example 1-5 were prepared in the same manner as in Example 1, except that a first additive having an ABA structure including the structural unit (A) represented by 2-1-1 and the structural unit (B) represented by the chemical formula 2-2-5 was used.

[0306]

[0307] Example 2-1

[0308] Except for changing the thiol-based structural unit content to 2 wt%, a first additive having an ABA structure comprising the structural unit (A) represented by 2-1-1 and the structural unit (B) represented by the chemical formula 2-2-1, the positive active material slurry of Example 2-1, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1-1.

[0309]

[0310] Example 2-2

[0311] Except for changing the thiol-based structural unit content to 10 wt%, a first additive having an ABA structure comprising the structural unit (A) represented by 2-1-1 and the structural unit (B) represented by the chemical formula 2-2-1, a positive electrode active material slurry of Example 2-2, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1-1.

[0312]

[0313] Examples 2-3

[0314] Except for changing the thiol-based structural unit content to 15 wt%, a first additive having an ABA structure comprising the structural unit (A) represented by 2-1-1 and the structural unit (B) represented by the chemical formula 2-2-1, a positive electrode active material slurry of Example 2-3, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1-1.

[0315]

[0316] Examples 2-4

[0317] Except for changing the thiol-based structural unit content to 20 wt%, a first additive having an ABA structure comprising the structural unit (A) represented by 2-1-1 and the structural unit (B) represented by the chemical formula 2-2-1, the positive active material slurry of Example 2-4, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1-1.

[0318]

[0319] Examples 2-5

[0320] Except for changing the thiol-based structural unit content to 30 wt%, a first additive having an ABA structure comprising the structural unit (A) represented by 2-1-1 and the structural unit (B) represented by the chemical formula 2-2-1, the positive active material slurry of Example 2-5, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1-1.

[0321]

[0322] Example 3-1

[0323] The positive active material slurry and lithium secondary battery of Example 3 were prepared in the same manner as in Example 1-1, except that a second additive represented by the following chemical formula 8-2 was used.

[0324] [Chemical Formula 8-2]

[0325]

[0326] (where R 7 They are all CH3)

[0327]

[0328] Example 3-2

[0329] The positive electrode active material slurry, positive electrode, and lithium secondary battery of Example 3-2 were prepared in the same manner as in Example 1-1, except that a second additive represented by the following chemical formula 8-2 was used.

[0330] [Chemical Formula 8-2]

[0331]

[0332] (where R 7 They are all CH2CH3)

[0333]

[0334] Example 3-3

[0335] The positive active material slurry, positive electrode, and lithium secondary battery of Example 3-3 were prepared in the same manner as in Example 1-1, except that a second additive represented by the following chemical formula 8-2 was used.

[0336] [Chemical Formula 8-2]

[0337]

[0338] (where R 7 They are all CH2CH2CH3)

[0339]

[0340] Example 4-1

[0341] The positive electrode active material slurry, positive electrode, and lithium secondary battery of Example 4-1 were prepared in the same manner as in Example 1-1, except that the weight ratio of the first additive and the second additive was changed to 1:4.

[0342]

[0343] Example 4-2

[0344] The positive electrode active material slurry, positive electrode, lithium, and lithium secondary battery of Example 4-2 were prepared in the same manner as in Example 1-1, except that the weight ratio of the first additive and the second additive was changed to 2:3.

[0345]

[0346] Example 4-3

[0347] The positive electrode active material slurry, positive electrode, and lithium secondary battery of Example 4-3 were prepared in the same manner as in Example 1-1, except that the weight ratio of the first additive and the second additive was changed to 4:1.

[0348]

[0349] Comparative Example 1 (Ref.)

[0350] A positive electrode active material slurry, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1-1, except that neither the first additive nor the second additive was used.

[0351]

[0352] Comparative Example 2

[0353] A positive electrode active material slurry, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1-1, except that only the first additive was used and the second additive was not used.

[0354]

[0355] Comparative Example 3

[0356] A positive electrode active material slurry, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1-1, except that the first additive was not used and the second additive was used.

[0357]

[0358] Comparative Example 4

[0359] A positive electrode active material slurry, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1-1, except that a commercially available SBR copolymer (Mw: 35,000 g / mol) was used instead of the first additive mentioned above.

[0360]

[0361] For reference, examples and comparative examples are summarized in Table 1 below.

[0362] Additive 1 Additive: 2 Additive (Weight Ratio) 1 Additive 2 Additive Chemical Formula Thiol Content * Chemical Formula Substituent Example 1-16-14 wt% 8-1-3:2 Example 1-26-24 wt% 8-1-3:2 Example 1-36-34 wt% 8-1-3:2 Example 1-46-44 wt% 8-1-3:2 Example 1-56-54 wt% 8-1-3:2 Example 2-16-12 wt% 8-1-3:2 Example 2-26-110 wt% 8-1-3:2 Example 2-36-115 wt% 8-1-3:2 Example 2-46-120 wt% 8-1-3:2 Example 2-56-130 wt% 8-1-3:2 Example 3-16-14 Wt% 8-2CH33:2 Example 3-26-14 Wt% 8-2CH2CH33:2 Example 3-36-14 Wt% 8-2CH2CH2CH33:2 Example 4-16-14 Wt% 8-1-1:4 Example 4-26-14 Wt% 8-1-2:3 Example 4-36-14 Wt% 8-1-4:1 Comparative Example 1-----Comparative Example 26-14 Wt%---Comparative Example 3--8-1--Comparative Example 4SBR-8-1-3:2

[0363]

[0364] * In Table 1 above, "thiol content" refers to the content of the thiol-based structural unit relative to the total amount of 100 weight% of the styrene-butadiene-based structural unit and the thiol-based structural unit.

[0365]

[0366] Evaluation Example 1: Bipolar Evaluation

[0367] Adhesion strength and ion conductivity were measured for the anodes prepared according to the examples and comparative examples using the following method, and the results are shown in Table 2 below.

[0368] (1) Adhesion

[0369] The anode adhesion and the peel strength of the upper and lower anodes were evaluated according to the examples and comparative examples.

[0370] Anode adhesion strength was measured by the following method. Anode plates according to the examples and comparative examples were cut to a width of 25 mm and a length of 100 mm. Samples for evaluating anode adhesion strength were prepared by attaching the anode active material layer surface to a glass substrate using adhesive tape (Celotape No. 405 manufactured by Nichiban Co., Ltd., registered trademark) as the adhesion surface. The samples were mounted on a peel tester (Instron 3400 series), and the stress was measured when the current collector was peeled off at a speed of 300 mm / min and separated in a 180° direction. The measurement was performed 5 times, and the average value was calculated as the peel strength. The adhesion strength (i.e., peel strength) was calculated according to Equation 1 below, and the results are shown in Table 1 below.

[0371] [Equation 1]

[0372] Adhesion (gf / mm) = Measured force (gf) / Length of adhesion area (mm)

[0373] The peel strength of the upper and lower anodes was measured using a SAICAS (Surface And Interfacial Cutting Analysis System) device as an oblique cutting device. The horizontal stress applied to the blade was compared as the peel strength when a blade having a diamond blade with a width of 1 mm was inserted obliquely from the electrode surface at a constant speed (horizontal: 6 μm / s, vertical: 0.6 μm / s), and after reaching the interface between the current collector and the electrode layer, the blade was moved horizontally at a constant speed (horizontal: 6 μm / s). The peel strength was calculated according to Equation 2 below, and the results are shown in Table 1 below.

[0374] [Equation 2]

[0375] Peel strength (kN / m) = Measured force (N) / Length of peel area (m)

[0376] The greater the adhesion (i.e., peel strength), the higher the bonding between the positive current collector and the positive active material layer, or between the positive active material layers themselves, and the more difficult it is to peel off the positive active material layer from the positive current collector or between the positive active material layers themselves.

[0377]

[0378] (2) Ionic conductivity

[0379] A symmetric cell was fabricated using the electrode plates prepared in the examples and comparative examples, and the ion conductivity was measured.

[0380] For the manufactured battery, in the EC-lab program, Frequency range = 100 kHz ~ 10 mHz, Amplitude = 14.1 mV, N d = 10 points per decade, E Range : -1 V; ionic conductivity was measured using the condition of 1 V.

[0381]

[0382] Adhesion strength Ionic conductivity (mS / cm) Peel test (gf / mm) Peel strength SAICAS Upper Lower Example 1-10.4 20.09 60.09 15.4 Example 1-20.4 00.09 40.09 14.7 Example 1-30.4 10.09 40.09 5.1 Example 1-40.46 0.09 80.09 45.2 Example 1-50.4 10.09 50.09 15.5 Example 2-10.38 0.09 50.08 84.8 Example 2-20.46 0.09 80.09 65.6 Example 2-30.49 0.09 90.09 55.3 Example Example 2-40.530.1010.0944.9 Example 2-50.570.1020.0934.7 Example 3-10.470.0970.0955.3 Example 3-20.490.0980.0955.1 Example 3-30.520.1010.0944.8 Example 4-10.380.0930.0925.1 Example 4-20.390.0940.0925.3 Example 4-30.450.0970.0905.6 Comparative Example 10.320.0930.0817.9 Comparative Example 20.370.0950.0885.1 Comparative Example 30.340.0940.0894.7 Comparative Example 40.360.0960.0914.9

[0383]

[0384] Evaluation Example 2: Battery Evaluation (Room Temperature Life Evaluation)

[0385] A coin full cell was fabricated using the cathode and anode prepared in the examples and comparative examples, a polyethylene separator, and an electrolyte.

[0386] For the manufactured lithium secondary battery, the battery life characteristics were measured after performing 200 charge-discharge cycles under the conditions of '25 ℃ 1.0 C charge (CC / CV, 4.5 V 0.02 C Cut-off) / 1.0 C discharge (CC, 3.0 V Cut-off)'. The life retention rate was calculated according to Equation 3 below. The results are shown in Table 3 below.

[0387] [Equation 3]

[0388] Life retention rate (%) = (Discharge capacity after 200 cycles / Initial discharge capacity) * 100

[0389]

[0390] Life @ 200 Cycles, 25 ℃ Example 1-187.1 Example 1-286.6 Example 1-386.8 Example 1-487.4 Example 1-586.9 Example 2-187.0 Example 2-288.3 Example 2-388.1 Example 2-487.6 Example 2-587.2 Example 3-187.0 Example 3-286.6 Example 3-386.2 Example 4-186.9 Example 4-287.2 Example 4-387.0 Comparative Example 186.2 Comparative Example 286.8 Comparative Example 386.5 Comparative Example 486.6

[0391]

[0392] Based on the above results, the electrolyte for a lithium secondary battery of one embodiment represented by the example can prevent the leaching of transition metals from the positive electrode active material and improve the performance of the battery by protecting the surface of the positive electrode.

[0393] Accordingly, by using the electrolyte for a lithium secondary battery of one embodiment, the performance of the lithium secondary battery can be improved regardless of the number of operating cycles and / or the ambient temperature during operation.

[0394]

[0395] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

[0396]

[0397] [Explanation of the symbol]

[0398] 100: Lithium secondary battery 10: Positive electrode

[0399] 11: Positive lead tab 12: Positive terminal

[0400] 20: Cathode 21: Cathode lead tab

[0401] 22: Negative terminal 30: Separator

[0402] 40: Electrode assembly 50: Case

[0403] 60: Sealing member 70: Electrode tab

[0404] 71: Positive tab 72: Negative tab

Claims

1. A positive electrode active material, an additive, and a solvent, wherein The above additive is A first additive comprising a styrene-butadiene-based structural unit and a thiol-based structural unit; and A second additive comprising a heterocyclic compound containing oxygen (O). including, Anode slurry composition for lithium secondary batteries.

2. In Paragraph 1, The first additive above is a block copolymer represented by the following chemical formula 1, Anode slurry composition for lithium secondary batteries: [Chemical Formula 1] ABA In the above chemical formula 1, A is a structural unit that is identical or different and is independently represented by the following chemical formula 2-1; B is a structural unit represented by the following chemical formula 2-2; [Chemical Formula 2-1] In the above chemical formula 2-1, R 1 is the same or different, and is H, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms; n is an integer from 1 to 6; [Chemical Formula 2-2] In the above chemical formula 2-2, R 2 is a substituent represented by the following chemical formula 3-1, 3-2, 3-3, 3-4, or 3-5; [Chemical Formula 3-1] In the above chemical formula 3-1, L 1 is a substituted or unsubstituted alkylene group having 1 to 30 carbon atoms; R 3 is OH, SO3M, or a substituent represented by the following chemical formula 4-1 or 4-2; where M is Li, Na, or K; [Chemical Formula 3-2] In the above chemical formula 3-2, L 2 is a substituted or unsubstituted alkylene group having 1 to 30 carbon atoms; L 3 is identical or different, and each independently a single bond, or a substituted or unsubstituted alkylene group having 1 to 30 carbon atoms; [Chemical Formula 5-1] In the above chemical formula 5-1, R 4 is H, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms; [Chemical Formula 5-2] In the above chemical formula 5-2, R 5 is H, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms.

3. In Paragraph 1, The above B is a structural unit represented by any one of the following chemical formulas 2-2-1 to 2-2-5, Anode slurry composition for lithium secondary batteries: [Chemical Formula 2-2-1] [Chemical Formula 2-2-2] [Chemical Formula 2-2-3] [Chemical Formula 2-2-4] [Chemical Formula 2-2-5] In the above chemical formulas 2-2-1 to 2-2-5, L 4 is an alkyl group having 1 to 11 carbon atoms.

4. In Paragraph 1, In the first additive above, With respect to a total amount of 100 weight% of the styrene-butadiene-based structural unit and the thiol-based structural unit, the content of the thiol-based structural unit is 2 to 40 weight%, Anode slurry composition for lithium secondary batteries.

5. In Paragraph 1, The weight-average molecular weight of the first additive measured by the GPC method is 10,000 to 250,000 g / mol, Anode slurry composition for lithium secondary batteries.

6. In Paragraph 1, The above second additive is represented by the following chemical formula 7, Anode slurry composition for lithium secondary batteries: [Chemical Formula 7] In the above chemical formula 7, X 1 is identical or different, and is O or S; X 1 At least one of them is O; R 6 The groups are identical or different, and each is independently H, or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms.

7. In Paragraph 1, The second additive is a compound selected from the following chemical formulas 8-1 and 8-2, Anode slurry composition for lithium secondary batteries: [Chemical Formula 8-1] [Chemical Formula 8-2] In the above chemical formula 8-2, R 7 The groups are identical or different, and each is independently H, or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms.

8. In Paragraph 1, With respect to 100 weight% of the total solid content of the anode slurry composition, the content of the first additive is 0.1 to 5 weight%, Anode slurry composition for lithium secondary batteries.

9. In Paragraph 1, With respect to 100 weight% of the total solid content of the anode slurry composition, the content of the second additive is 0.1 to 5 weight%, Anode slurry composition for lithium secondary batteries.

10. In Paragraph 1, The content ratio of the first additive and the second additive in the anode slurry composition is 10:1 to 1:10 by weight, Anode slurry composition for lithium secondary batteries.

11. In Paragraph 1, Based on 100 parts by weight of the above positive active material, the above first additive + above second additive is 0.5 to 5 parts by weight, Anode slurry composition for lithium secondary batteries.

12. In Paragraph 1, The above positive electrode active material is one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. Anode slurry composition for lithium secondary batteries.

13. In Paragraph 12, The above positive active material is a lithium nickel-based oxide represented by the following chemical formula 11, Anode slurry composition for lithium secondary batteries: [Chemical Formula 11] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 In the above chemical formula 11, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1 and; M 1 and M 2 Each is independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr; X is one or more elements selected from the group consisting of F, P, and S. 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.

4.

14. In Paragraph 1, The above anode slurry composition further comprises a binder, a conductive material, or a combination thereof, Anode slurry composition for lithium secondary batteries.

15. In Paragraph 1, The above solvent is N-Methyl-2-pyrrolidone (NMP), p-xylene, tetralin, octyl acetate, hexyl butyrate, or a combination thereof. Anode slurry composition for lithium secondary batteries.

16. In Paragraph 1, With respect to a total amount of 100 weight% of the anode slurry composition, the content of the solvent is 10 to 50 weight%, Anode slurry composition for lithium secondary batteries.

17. A positive current collector and a positive active material layer located on at least one surface of the positive current collector, and The above positive active material layer Includes positive electrode active material and additives, The above additive is A first additive comprising a copolymer of a styrene-butadiene-based polymer and a thiol-based monomer; and A second additive comprising a heterocyclic compound containing oxygen (O). including, Cathode for lithium secondary batteries.

18. In the 17th, The thickness of the positive electrode active material layer is 10 to 200 μm, Cathode for lithium secondary batteries.

19. The positive electrode of Paragraph 17 or 18; cathode; and Containing electrolytes, Lithium secondary battery.

20. In Paragraph 19, The above lithium secondary battery is a lithium-ion battery, a solid-state battery, or a lithium-sulfur battery. Lithium secondary battery.

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