Recovery fluid for lithium secondary battery, and lithium secondary battery using same

Abstract

The present invention relates to a recovery fluid for a lithium secondary battery and a lithium secondary battery using same, wherein: the recovery fluid for a lithium secondary battery is a recovery fluid added to an electrolyte in order to supply lithium ions to a lithium secondary battery including the electrolyte, and has an ionic composition including an ionic compound and a dispersion medium; the ionic compound includes a lithium cation and a radical anion; the radical anion includes an arenide-based radical anion; and at least one hydrogen in the arenide-based radical anion is substituted with deuterium.

Description

Recovery solution for lithium secondary batteries and lithium secondary batteries using the same

[0001] This invention relates to a recovery solution for a lithium secondary battery and a lithium secondary battery using the same.

[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] With the recent increase in the use of lithium-ion batteries, research on methods to recycle them is actively underway.

[0006] A widely known method to date involves physically, chemically, and / or metallurgically decomposing used lithium-ion batteries to recover raw materials such as positive electrode active materials and negative electrode active materials.

[0007]

[0008] One embodiment provides a recovery solution for a lithium secondary battery that can directly improve the lifespan of the lithium secondary battery without decomposing the lithium secondary battery.

[0009]

[0010] One embodiment provides a recovery solution for a lithium secondary battery, wherein the recovery solution added to the electrolyte to supply lithium ions to the lithium secondary battery comprising the electrolyte comprises an ionic composition including an ionic compound and a dispersion medium; wherein the ionic compound comprises a lithium cation and a radical anion; and wherein the radical anion comprises an arenide-based radical anion; and wherein at least one hydrogen in the arenide-based radical anion is substituted with deuterium.

[0011] Another embodiment provides a lithium secondary battery using the above recovery solution.

[0012]

[0013] According to the above embodiment, if a recovery solution is injected while the capacity of a lithium secondary battery is partially reduced, the lifespan of the lithium secondary battery can be directly improved without disassembling the battery.

[0014]

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

[0016]

[0017] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0018] 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.

[0019] 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."

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] Unless otherwise defined in this specification, the particle size may be the average particle size. Additionally, the particle size refers to the average particle size (D50), which means the diameter of the particle whose cumulative volume in the particle size distribution is 50% by volume. The average particle size (D50) may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. Alternatively, the average particle size (D50) value may be obtained by measuring using a measuring device utilizing dynamic light scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Alternatively, it may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasound of about 28 kHz at an output of 60 W, and then the average particle size (D50) at 50% of the particle size distribution in the measuring device can be calculated.

[0025]

[0026] (Recovery solution for lithium secondary batteries)

[0027] One embodiment provides a recovery solution for a lithium secondary battery, wherein the recovery solution added to the electrolyte to supply lithium ions to the lithium secondary battery comprising the electrolyte comprises an ionic composition including an ionic compound and a dispersion medium; wherein the ionic compound comprises a lithium cation and a radical anion; and wherein the radical anion comprises an arenide-based radical anion; and wherein at least one hydrogen in the arenide-based radical anion is substituted with deuterium.

[0028]

[0029] (1) In large lithium secondary batteries used in a relatively well-controlled environment, the battery capacity may be reduced due to a decrease in cations and / or anions in the electrolyte rather than damage to the positive and / or negative active materials.

[0030] Accordingly, according to the above embodiment, if a recovery solution is injected while the capacity of the lithium secondary battery is partially reduced, the lifespan of the lithium secondary battery can be directly improved without disassembling the battery.

[0031]

[0032] (2) A recovery solution according to one embodiment comprises an ionic composition including an ionic compound and a dispersion medium; the ionic compound decomposes into lithium cations and radical anions.

[0033] As the above radical anion, a radical anion of an arenide-based compound can be used. The above arenide-based compound (e.g., naphthalene, biphenyl, etc.) can contribute to restoring the reduction of cations and / or anions in the electrolyte.

[0034]

[0035] (3) Since the radical anion excluding the lithium cation of the arenide-based compound is in a chemically unstable state, in one embodiment, at least one hydrogen in the arenide-based radical anion may be substituted with deuterium. Hereinafter, in one embodiment, the “radical anion excluding the hydrogen cation of the arenide-based compound” may be abbreviated as “arenide-based radical anion”.

[0036] When at least one hydrogen in the above arenaide-based radical anion is substituted with deuterium, an isotope effect is realized, and chemical stabilization compared to a compound without deuterium substitution, such as zero-point energy reduction and electric energy stabilization, can be achieved.

[0037] Accordingly, when using a recovery solution according to one embodiment containing an arenide-based radical anion in which at least one hydrogen is substituted with deuterium, compared to using a recovery solution containing an arenide-based radical anion not substituted with deuterium, an effect of improving the capacity of a lithium secondary battery can be seen even at a low concentration and / or for a short time.

[0038]

[0039] (4) In one embodiment, the recovery solution may use the ionic composition containing the ionic compound and the dispersion medium alone, or a separate electrolyte may be mixed with the ionic composition.

[0040] As will be described in more detail later, the degree of capacity improvement of the lithium secondary battery can be controlled by changing the concentration of deuterium in the recovery solution. Generally, a recovery solution with a high concentration of deuterium can improve capacity even at a low concentration, and this can be taken into account when adjusting the volume ratio of the separate electrolyte mixture.

[0041]

[0042] Below, a recovery solution according to one embodiment is described in more detail.

[0043]

[0044] arenide compounds

[0045] The above radical anion may include an anion of an 'arenide-based compound represented by the following chemical formula 1-1 or 1-2':

[0046] [Chemical Formula 1-1]

[0047]

[0048] [Chemical Formula 1-2]

[0049]

[0050] The description of the above chemical formulas 1-1 and 1-2 is as follows.

[0051] R 1 and R 2 Each may independently be hydrogen, deuterium, halogen group, hydroxyl group, sulfonyl group, amino group, cyano group, carbonyl group, acyl group, amide group, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms.

[0052] However, R 1 At least one of them may be deuterium; R 2 At least one of them may be deuterium.

[0053] m1 can be an integer from 1 to 4+(4*n1); and m2 can be an integer from 1 to 5+(5*n2).

[0054] n1 and n2 can each independently be integers from 1 to 10.

[0055]

[0056] For example, when n1 = 1 and m1 = 8, the arenaide compound represented by the above chemical formula 1-1 may be naphthalene. In this case, R1 Four to eight of them may be deuterium; and R that is not deuterium 1 All of it can be hydrogen.

[0057] Independently thereof, when n2 = 1 and m2 = 10, the areide compound represented by Formula 1-1 above may be biphenyl. In this case, R 2 Four to eight of them may be deuterium; and R that is not deuterium 2 All of them can be hydrogen.

[0058]

[0059] ionic compounds

[0060] The above ionic compound can be represented by the following chemical formula 2-1 or 2-2:

[0061] [Chemical Formula 2-1]

[0062] [(x1)(Li + )]·[(Ar1) x1- ]

[0063] [Chemical Formula 2-2]

[0064] [(x2)(Li + )]·[(Ar1) x2- ]

[0065] The description of the above chemical formulas 2-1 and 2-2 is as follows.

[0066] Ar1 may be the above chemical formula 1-1; and Ar2 may be the above chemical formula 1-2.

[0067] x1 can be an integer from 1 to 4+(4*n1); and x2 can be an integer from 1 to 5+(5*n2). For example, x1 and x2 can both be 1.

[0068] Here, the definitions of the above chemical formulas 1-1, 1-2, n1, and n2 are as above.

[0069]

[0070] For example, representative examples of the above ionic compounds are as follows:

[0071] [Chemical Formula 3-1]

[0072]

[0073] [Chemical Formula 3-2]

[0074] .

[0075]

[0076] Molar concentration of ionic compounds

[0077] The molar concentration of the ionic compound in the ionic composition may be 0.1 to 3 M, 0.5 to 2 M, or 0.7 to 1.5 M.

[0078] The molar concentration of the above ionic compound can be controlled by adjusting the content of the above ionic compound in the above ionic composition, and / or by adding the above separate electrolyte (hereinafter referred to as the 'first electrolyte').

[0079]

[0080] dispersion medium

[0081] The dispersion medium is not particularly limited as long as it is a substance capable of ionically decomposing the ionic compound, but may include, for example, dimethyl ether (DME), tetrahydrofuran (THF), or a combination thereof.

[0082]

[0083] Separate electrolyte (first electrolyte)

[0084] The above recovery solution may further include a first electrolyte as a diluent and a lithium-ion charging solution.

[0085] The volume ratio of the ionic composition and the first electrolyte may be 0.1:1 to 1:1, 0.3 to 1:1, 0.5:1 to 1:1, or 0.75:1 to 1:1. Here, by adjusting the concentration of deuterium in the recovery solution through changing the volume ratio of the ionic composition and the first electrolyte, the degree of capacity improvement of the lithium secondary battery can be controlled.

[0086]

[0087] The first electrolyte may include a first lithium salt and a first solvent.

[0088] The first lithium salt and the first solvent are not particularly limited as long as they are lithium salts and non-aqueous organic solvents commonly used in the electrolytes of lithium secondary batteries.

[0089] The above lithium salt is a material that is dissolved in an organic solvent and acts as a source of lithium ions within the battery, enabling the operation of a basic lithium secondary battery and facilitating the movement of lithium ions between the positive and negative electrodes.

[0090] 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).

[0091] The molar concentration of the first lithium salt in the above electrolyte may be 0.1 to 3 M, 0.5 to 2 M, or 0.7 to 1.5 M.

[0092] In addition, the above-mentioned non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, a non-protic solvent, or a combination thereof.

[0093] 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.

[0094] The above-mentioned non-aqueous organic solvent can be used alone or in a mixture of two or more types.

[0095] 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.

[0096] The first 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.

[0097] The above-mentioned non-aqueous organic solvent can be used alone or in a mixture of two or more types.

[0098] 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.

[0099] 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.

[0100] For example, the first electrolyte may be a mixture of lithium salt (LiPF6) at a concentration of 1.1 M in a carbonate-based solvent in which ethylene carbonate (EC):dimethyl carbonate (DMC):ethylmethyl carbonate (EMC) are mixed in a volume ratio of 30:40:30.

[0101]

[0102] (Lithium secondary battery)

[0103] Another embodiment provides a lithium secondary battery comprising: a positive electrode including a positive active material; a negative electrode including a negative active material; a separator located between the positive electrode and the negative electrode; and a second electrolyte, wherein a recovery solution according to the above-described embodiment is added to the second electrolyte during or after operation of the lithium secondary battery.

[0104] This can directly improve the lifespan of lithium secondary batteries without disassembling them.

[0105]

[0106] The above recovery solution may be added in an amount of 0.1 to 1 mL, 0.3 to 1 mL, or 0.3 to 0.5 mL. Within this range, the lifespan of the lithium secondary battery can be directly improved.

[0107]

[0108] The first electrolyte and the second electrolyte may have the same composition.

[0109]

[0110] Hereinafter, descriptions that overlap with the above-mentioned content will be omitted, and a lithium secondary battery according to one embodiment will be described in detail.

[0111]

[0112] positive electrode active material

[0113] 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.

[0114] 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.

[0115] 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); Li a 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).

[0116] 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.

[0117] 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.

[0118] [Chemical Formula 11]

[0119] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0120] 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, and X is one or more elements selected from the group consisting of F, P, and S.

[0121] 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.

[0122] [Chemical Formula 12]

[0123] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0124] 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.

[0125] [Chemical Formula 13]

[0126] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0127] In the above chemical formula 13, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.4, and 0≤b3≤0.1, and M 4 is 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.

[0128] [Chemical Formula 14]

[0129] Li a4 Ni x4 Mny4 M 5 z4 O 2-b4 X b4

[0130] 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.

[0131] 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.

[0132]

[0133] anode

[0134] 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. The positive electrode may be a positive electrode manufactured using an insulating composition for a lithium secondary battery according to the aforementioned embodiment.

[0135] The above positive active material layer includes a positive active material and may further include a binder and / or a conductive material.

[0136] For example, the above anode may further include an additive that can serve as a sacrificial anode.

[0137] The content of the positive active material is 90% to 99.5% by weight with respect to 100% by weight of the positive active material layer, and 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.

[0138] 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.

[0139] 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.

[0140]

[0141] cathode active material

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] The above Si-based or Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0149]

[0150] cathode

[0151] 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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, Ketjen black, 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.

[0159] 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.

[0160]

[0161] electrolyte

[0162] The third electrolyte for a lithium secondary battery comprises a non-aqueous organic solvent and a lithium salt.

[0163] The above-mentioned non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0164] 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.

[0165] 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.

[0166] The above-mentioned non-aqueous organic solvent can be used alone or in a mixture of two or more types.

[0167] 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.

[0168] 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.

[0169] 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).

[0170]

[0171] separator

[0172] 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.

[0173] 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.

[0174] 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.

[0175] The above organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0176] 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.

[0177] 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.

[0178]

[0179] lithium secondary battery

[0180] 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 the third 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.

[0181] In addition, the lithium secondary battery according to FIGS. 1 to 4 may further include an injection port (not shown) for injecting the recovery solution into the third electrolyte.

[0182]

[0183] 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.

[0184]

[0185] 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.

[0186]

[0187] (Preparation Example and Comparative Preparation Example: Preparation of Ionic Composition)

[0188] Preparation Example 1

[0189]

[0190] 1.07 g of N-Bromosuccimide, 15 mg of AuCl3, and 10 mL of dichloroethane were placed in a 200 mL flask under nitrogen filling conditions, and 5 mL of the compound represented by the following chemical formula A (Cas No. 1076-43-3) was added while stirring, and the mixture was stirred at 80 °C for 24 hours. After the reaction was complete, the solvent was removed under reduced pressure and the residue was filtered to obtain d5-bromobenzene as an intermediate.

[0191] [Chemical Formula A]

[0192]

[0193] 176 mg of NaNH2, 17 mg of tBuOK, and 10 mL of THF were added to a 200 mL flask and stirred, and 470 mg of d5-bromobenzene and 3.06 g of furan were added and stirred at 50°C for 15 hours. The reaction mixture was diluted with 5 mL of Et2O, passed through a silica gel pad, and the filtrate was washed with salt water and separated into layers using Et2O. Subsequently, the organic layer was extracted, dried and filtered with MgSO4, and the solvent was removed under reduced pressure. The obtained residue was mixed with 18 mg of Re2O7, 31.12 mg of P(OPh)3, and 9 mL of toluene and stirred at 80°C for 18 hours, then the solvent was removed under reduced pressure and the residue was filtered to obtain a compound represented by the following chemical formula B (d4-naphthalene).

[0194] [Chemical Formula B]

[0195]

[0196] A 1.0 mol / L solution is prepared by dissolving the compound represented by Chemical Formula B in anhydrous THF, and then an equal molar amount of lithium metal (Honjo Metal Co., Ltd., Japan) is added and the solution is stirred. The resulting Li-Naph solution is mixed with a LiPF6-based electrolyte solution in a 1:1 volume ratio to prepare an ionic compound containing lithium cations and naphthalene radical anions. The chemical formula of the final product is as shown in 3-1 below:

[0197] [Chemical Formula 3-1]

[0198] .

[0199]

[0200] Preparation Example 2

[0201] Under nitrogen-filled conditions, 12.8 g of naphthalene (Cas No. 91-20-3) was dissolved in 250 mL of the compound represented by Chemical Formula A above in a 200 mL flask, followed by the gradual addition of 5.4 g of trifluoromethane sulfonic acid, and the mixture was stirred at 80°C for 2 hours. After the reaction was complete, a solution of 7 g of triethylamine dissolved in 100 mL of D2O was added and stirred, followed by extraction twice with dichloromethane. The extracted organic layer was concentrated, dissolved in toluene, and filtered. Subsequently, the mixture was concentrated under reduced pressure and recrystallized with dichloromethane / hexane to obtain the compound represented by Chemical Formula C below (d8-naphthalene).

[0202] [Chemical Formula C]

[0203]

[0204] A 1.0 mol / L solution is prepared by dissolving the compound represented by chemical formula C in anhydrous THF, and then an equal molar amount of lithium metal (Honjo Metal Co., Ltd., Japan) is added and the solution is stirred. The resulting Li-Naph solution is mixed with a LiPF6-based electrolyte solution in a 1:1 volume ratio to prepare an ionic compound containing lithium cations and naphthalene radical anions. The chemical formula of the final product is as shown in 3-2 below:

[0205] [Chemical Formula 3-2]

[0206] .

[0207]

[0208] Manufacturing Comparative Example 1

[0209] An ionic composition was prepared in the same manner as in Preparation Example 1, except that unsubstituted naphthalene itself was used instead of naphthalene substituted with deuterium.

[0210]

[0211] (Examples and Comparative Examples: Preparation of Recovery Solution)

[0212] Example 1-1

[0213] The ionic composition of Preparation Example 1 was mixed with the first electrolyte in a volume ratio of 0.5:1 to prepare the recovery solution of Example 1-1.

[0214] The first electrolyte above is a mixture of lithium salt (LiPF6) at a concentration of 1.1 M in a carbonate-based solvent in which ethylene carbonate (EC):dimethyl carbonate (DMC):ethylmethyl carbonate (EMC) are mixed in a volume ratio of 30:40:30.

[0215]

[0216] Examples 1-2

[0217] The recovery solution of Example 1-2 was prepared in the same manner as Example 1-1, except that the volume ratio of the ionic composition of Preparation Example 1 and the first electrolyte was changed to 0.75:1.

[0218]

[0219] Examples 1-3

[0220] The recovery solution of Example 1-3 was prepared in the same manner as Example 1-1, except that the volume ratio of the ionic composition of Preparation Example 1 and the first electrolyte was changed to 1:1.

[0221]

[0222] Example 1-1

[0223] The recovery solution of Example 2-1 was prepared in the same manner as Example 1-1, except that the ionic composition of Preparation Example 1 was changed to the ionic composition of Preparation Example 2.

[0224]

[0225] Example 2-2

[0226] The recovery solution of Example 2-2 was prepared in the same manner as Example 1-1, except that the volume ratio of the ionic composition of Preparation Example 2 and the first electrolyte was changed to 0.75:1.

[0227]

[0228] Examples 2-3

[0229] The recovery solution of Example 2-3 was prepared in the same manner as Example 1-1, except that the volume ratio of the ionic composition of Preparation Example 2 and the first electrolyte was changed to 1:1.

[0230]

[0231] Comparative Example 1

[0232] The recovery solution of Comparative Example 1 was prepared in the same manner as in Example 1-1, except that the ionic composition of Preparation Example 1 was changed to the ionic composition of Preparation Comparative Example 1.

[0233]

[0234] Comparative Example 2

[0235] The recovery solution of Comparative Example 2 was prepared in the same manner as in Example 1-1, except that the volume ratio of the ionic composition of Comparative Example 1 and the first electrolyte was changed to 0.75:1.

[0236]

[0237] Comparative Example 3

[0238] The recovery solution of Comparative Example 3 was prepared in the same manner as in Example 1-1, except that the volume ratio of the ionic composition of Comparative Example 1 and the first electrolyte was changed to 1:1.

[0239]

[0240] Evaluation Example 1

[0241] (1) Manufacturing of lithium secondary batteries

[0242] Aluminum foil with a thickness of 10 μm was used as the positive current collector.

[0243] LiNi as a positive electrode active material 1 / 3 Co 1 / 3 Al 1 / 3 O2, polyvinylidene fluoride (PVDF) as a binder, and carbon as a conductive agent were mixed in a weight ratio of 88:8:4, and then dispersed in N-methyl-2-pyrrolidone to prepare an anode slurry. This slurry was coated onto the aluminum foil to a thickness of 10 μm to form an anode active material layer.

[0244] The above cathode active material slurry 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.

[0245] As a cathode active material, artificial graphite, styrene-butadiene rubber binder, and carboxymethylcellulose were mixed in a weight ratio of 98:1:1 and dispersed in distilled water to prepare a cathode active material slurry.

[0246] The above cathode active material slurry was coated onto a 10㎛ thick Cu foil, dried at 100℃, and then pressed to form a cathode active material layer.

[0247] An electrode assembly was manufactured by assembling the above-mentioned positive and negative electrodes, and after housing the electrode assembly in a rectangular case, a second electrolyte was injected to produce a lithium secondary battery.

[0248] The second electrolyte above is the same as the first electrolyte, and is a carbonate-based solvent in which ethylene carbonate (EC):dimethyl carbonate (DMC):ethylmethyl carbonate (EMC) are mixed in a volume ratio of 30:40:30, and a lithium salt (LiPF6) is mixed at a concentration of 1.1 M.

[0249] (2) Manufacturing of lithium secondary batteries for evaluation

[0250] The first lithium secondary battery manufactured in (1) above was charged to a State of Charge (SOC) of 50% and a positive electrode was obtained. A lithium secondary battery for evaluation was manufactured in the same manner as in (1) above, except that the positive electrode obtained therefrom was used.

[0251] (3-1) Evaluation of Electrochemical Characteristics of Evaluation Lithium Secondary Batteries

[0252] For the electrolyte (second electrolyte) of the lithium secondary battery for evaluation prepared in (2) above, 0.5 mL of each recovery solution of Examples 1-1 to 1-3, 2-1 to 2-3, and Comparative Examples 1-1 to 1-3 was added, and then an initial charge-discharge was performed by charging at 4.1 V at 1.2 mA and discharging at 3.0 V. For the lithium secondary battery that underwent the initial charge-discharge, charging at 4.1 V at 1.2 mA followed by CV charging for 5 hours and then discharging at 3.0 V at 0.6 mA was considered as '1 cycle,' and 'n cycles' were performed.

[0253] The number of cycles n above was evaluated by substituting it into (4) below, and the result was recorded in Table 1.

[0254] (3-2) Evaluation of Electrochemical Characteristics of Evaluation Lithium Secondary Batteries

[0255] For the electrolyte (second electrolyte) of the lithium secondary battery for evaluation prepared in (2) above, 0.3 mL or 0.5 mL of each recovery solution of Examples 1-3, Examples 2-3, and Comparative Example 3 was added, and then the battery was charged at 4.1 V at 1.2 mA and discharged at 3.0 V for initial charge and discharge. For the lithium secondary battery that was initially charged and discharged, charging at 4.1 V at 1.2 mA followed by CV charging for 5 hours followed by discharging at 3.0 V at 0.6 mA was considered as '1 cycle', and 'n' cycles were performed.

[0256] The above number of cycles n was evaluated by substituting into (4) below, and the results were recorded in Table 2.

[0257] (4) Evaluation

[0258] (i) 75 < n ≤ 100 : 5

[0259] (ii) 50 < n ≤ 75 : 3

[0260] (iii) 30 < n ≤ 50 : 2

[0261] (iv) 10 < n ≤ 30 : 1

[0262] (v) 0 ≤ n ≤ 10 : 0

[0263]

[0264] Recovery solution identical (0.5 mL) conditions Deuterium-substituted hydroionic composition: First electrolyte (v:v) Evaluation Comparative Example 1 0.5:10 Comparative Example 2 0.75:12 Comparative Example 3 0.1:13 Example 1-1 4.5:14 Example 1-2 4.75:15 Example 1-3 4.1:15 Example 2-18 0.5:15 Example 2-28 0.75:15 Example 2-38 1.15

[0265] Deuterium Substitution Water Recovery Solution Difference (0.3 or 0.5 mL) Condition 0.3 mL 0.5 mL Comparative Example 3013 Example 1-3445 Example 2-3855

[0266] When the capacity of a lithium secondary battery is partially reduced, if a recovery solution for a lithium secondary battery, represented by Examples 1-1 to 1-3 and Examples 2-1 to 2-3, is injected, the lifespan of the lithium secondary battery can be directly improved without disassembling the battery.

[0267] 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.

[0268] [Explanation of the symbol]

[0269] 100: Lithium secondary battery 10: Positive electrode

[0270] 11: Positive lead tab 12: Positive terminal

[0271] 20: Cathode 21: Cathode lead tab

[0272] 22: Negative terminal 30: Separator

[0273] 40: Electrode assembly 50: Case

[0274] 60: Sealing member 70: Electrode tab

[0275] 71: Positive tab 72: Negative tab

Claims

1. A recovery solution added to the electrolyte to supply lithium ions to a lithium secondary battery containing the electrolyte, wherein 1. An ionic composition comprising an ionic compound and a dispersion medium; The above ionic compound is It includes lithium cations and radical anions; The above radical anion is Includes arenide-based radical anions; At least one hydrogen in the above-mentioned arenaide radical anion is substituted with deuterium, Recovery solution for lithium secondary batteries.

2. In Paragraph 1, The above-mentioned arenide radical anion comprises an anion of an arenide compound represented by the following chemical formula 1-1 or 1-2, Recovery solution for lithium secondary batteries: [Chemical Formula 1-1] [Chemical Formula 1-2] In the above chemical formulas 1-1 and 1-2, R 1 and R 2 Each is independently hydrogen, deuterium, halogen group, hydroxyl group, sulfonyl group, amino group, cyano group, carbonyl group, acyl group, amide group, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms; R 1 At least one of them is deuterium; R 2 At least one of them is deuterium; m1 is an integer from 1 to 4+(4*n1); m2 is an integer from 1 to 5+(5*n2); n1 and n2 are each independently integers from 1 to 10.

3. In Paragraph 2, n1 is 1, m1 is 8, and R 1 Of these, 4 to 8 are deuterium, and R is not deuterium. 1 It is hydrogen or; n2 is 1, m2 is 10, and R 2 Of these, 4 to 8 are deuterium, and R is not deuterium. 2 is hydrogen, Recovery solution for lithium secondary batteries:

4. In Paragraph 3, The above ionic compound is represented by the following chemical formula 2-1 or 2-2, Recovery solution for lithium secondary batteries: [Chemical Formula 2-1] [(x1)(Li + )]·[(Ar1) x1- ] [Chemical Formula 2-1] [(x2)(Li + )]·[(Ar1) x2- ] In the above chemical formulas 2-1 and 2-2, Ar1 is the above chemical formula 1-1; Ar2 is the above chemical formula 1-2; x1 is an integer from 1 to 4+(4*n1); x2 is an integer from 1 to 5+(5*n2); The definitions of the above chemical formulas 1-1, 1-2, n1, and n2 are as in paragraph 2.

5. In Paragraph 4, x1 and x2 are both 1, Recovery solution for lithium secondary batteries.

6. In Paragraph 1, The molar concentration of the ionic compound in the ionic composition is 0.1 to 3 M, Recovery solution for lithium secondary batteries.

7. In Paragraph 1, The dispersion medium comprises dimethyl ether (DME), tetrahydrofuran (THF), or a combination thereof. Recovery solution for lithium secondary batteries.

8. In Paragraph 1, The above recovery solution further comprises a first electrolyte, and The above first electrolyte is A first lithium salt and a first solvent comprising Recovery solution for lithium secondary batteries.

9. In Paragraph 1, The volume ratio of the ionic composition and the first electrolyte in the above recovery solution is 0.1:1 to 1:1, Recovery solution for lithium secondary batteries.

10. In Paragraph 1, The first lithium salt above is 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 SO2)(x and y are integers from 1 to 20), comprising one or more selected from lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalate)phosphate (LiDFOB), and lithium bis(oxalate)borate (LiBOB), Recovery solution for lithium secondary batteries.

11. In Paragraph 1, The molar concentration of the first lithium salt in the above electrolyte is 0.1 to 3 M, Recovery solution for lithium secondary batteries.

12. In Paragraph 1, The first solvent is a non-aqueous organic solvent comprising carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvents, aprotic solvents, or a combination thereof. Recovery solution for lithium secondary batteries.

13. Anode comprising a positive active material; A cathode comprising a cathode active material; A separator located between the anode and the cathode; and A lithium secondary battery comprising a second electrolyte, A recovery solution according to any one of claims 1 to 12 is added to the second electrolyte during or after operation of the lithium secondary battery, Lithium secondary battery.

14. In Paragraph 13, The above recovery solution is used in an amount of 0.1 to 1 mL, Lithium secondary battery.

15. In Paragraph 13, The first electrolyte and the second electrolyte are identical. Lithium secondary battery.

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