Electrolyte and rechargeable lithium battery including same

Abstract

The invention relates to an electrolyte and a rechargeable lithium battery including the same. The electrolyte comprises a non-aqueous organic solvent, a lithium salt and a lanthanide metal imide salt.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0090557 filed on July 12, 2023 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] One or more embodiments of the present disclosure relate to an electrolyte and a rechargeable lithium battery including the same. Background Art

[0004] Recently, with the rapid popularization of electronic devices using batteries (such as mobile phones, laptop computers and electric vehicles), the demand for rechargeable lithium batteries with relatively high energy density and relatively high capacity has increased rapidly. Accordingly, research and development to improve the performance of rechargeable lithium batteries is actively underway.

[0005] The rechargeable lithium battery includes positive and negative electrodes, each including an active material capable of intercalating and deintercalating lithium ions, and an electrolyte, and generates electric energy through oxidation and reduction reactions when lithium ions are intercalated / deintercalated at the positive and negative electrodes.

[0006] One of the latest developments in rechargeable lithium batteries involves fast charging. However, when a rechargeable lithium battery is fast charged, lithium dendrites may precipitate on the negative electrode surface (e.g., at the interface between the negative electrode and the electrolyte), and these lithium dendrites may deteriorate the life cycle characteristics of the rechargeable lithium battery and / or may increase the resistance.

[0007] Accordingly, there is a need or desire for an electrolyte that improves the fast charging performance of a rechargeable lithium battery while minimizing or reducing degradation of life cycle characteristics and / or increase in resistance.

[0008] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art. Summary of the invention

[0009] Aspects of one or more embodiments of the present disclosure are directed to an electrolyte that improves fast charging performance while minimizing or reducing degradation of life cycle characteristics and / or increase in resistance.

[0010] Aspects of one or more embodiments of the present disclosure are directed to a rechargeable lithium battery including an electrolyte.

[0011] Aspects of one or more embodiments of the present disclosure relate to an electrolyte including a non-aqueous organic solvent, a lithium salt, and a lanthanide metal imide salt.

[0012] Aspects of one or more embodiments of the present disclosure are directed to a rechargeable lithium battery including: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte.

[0013] In the electrolyte according to aspects of one or more embodiments, by adding the lanthanide metal imide salt, a lithium-philic film may be formed on the surface of the negative electrode, and precipitation at the interface between the negative electrode and the electrolyte may be minimized or reduced.

[0014] In the rechargeable lithium battery according to aspects of one or more embodiments, by applying an electrolyte, fast charging performance may be improved while minimizing or reducing degradation of life cycle characteristics and / or increase in resistance.

[0015] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate example embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. In the drawings:

[0017] Figure 1 1 is a schematic perspective exploded view showing a rechargeable lithium battery according to one or more embodiments of the present disclosure.

[0018] Description of Reference Numerals

[0019] 100: Rechargeable lithium battery

[0020] 10: Positive electrode

[0021] 20: Negative electrode

[0022] 30: Diaphragm

[0023] 50: Shell

[0024] 60: Sealing member DETAILED DESCRIPTION

[0025] The present disclosure can be modified in many alternative forms, and therefore specific embodiments will be illustrated in the drawings and described in more detail. However, it should be understood that this is not intended to limit the present disclosure to the particular form disclosed, but is intended to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present disclosure.

[0026] Hereinafter, the embodiments of the present disclosure will be described in more detail. However, the present disclosure can be implemented in various different forms and should not be construed as being limited to the embodiments explained herein. On the contrary, these embodiments are provided as examples so that the present disclosure will be thorough and complete, and will fully convey the aspects and features of the present disclosure to those skilled in the art. Accordingly, processes, elements, and techniques that are not necessary for a person of ordinary skill in the art to fully understand the aspects and features of the present disclosure may not be described.

[0027] When specific definitions are provided in other ways, it will be understood that when an element (such as a region, layer, film, region, or portion) is referred to as being "on," "connected to," or "coupled to" another element (such as a region, layer, film, region, or portion), it can be directly on, directly connected to, or directly coupled to another element (such as a region, layer, film, region, or portion), or one or more intervening elements may be present. In addition, it will be understood that when an element is referred to as being "between" two elements, it can be the only element between the two elements, or one or more intervening elements may also be present.

[0028] It will be further understood that the terms “comprises,” “comprising,” “includes,” “including,” “have,” “having,” “contain,” and “containing,” when used in the present specification, specify the presence of stated features, integers, steps, operations, elements, components and / or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0029] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0030] As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. In addition, unless specifically stated otherwise, "A or B" may mean "including A, including B, or including A and B".

[0031] As used herein, "appropriate" may refer to an amount, level, combination, etc. that is generally available, commonly used, and / or understandable to one of ordinary skill in the art.

[0032] As used herein, "combinations thereof" may refer to mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0033] Electrolyte

[0034] One or more embodiments provide an electrolyte including a non-aqueous organic solvent, a lithium salt, and a lanthanide metal imide salt.

[0035] When a lanthanide metal imide salt is added as an additive to an electrolyte, a lithium-philic film can be formed on the surface of the negative electrode, and the precipitate at the interface between the negative electrode and the electrolyte can be minimized or reduced. This makes it possible to achieve a rechargeable lithium battery with improved safety without deteriorating fast charging performance. This effect and / or aspect of the lanthanide metal imide salt is superior to that of lanthanide metal nitrates, lanthanide metal phosphates, etc., and can be confirmed in the evaluation examples described in more detail later.

[0036] Content of lanthanide metal imide salt

[0037] If the content (e.g., amount) of the lanthanide metal imide salt in 100 wt% of the electrolyte is less than about 0.05 wt%, the effect of suppressing or reducing the increase in resistance and / or the improvement of fast charging performance and life cycle characteristics will be minimal, so the content (e.g., amount) of the lanthanide metal imide salt should be controlled or selected to be about 0.05 wt% or greater. In one or more embodiments, the upper limit of the content (e.g., amount) of the lanthanide metal imide salt in 100 wt% of the electrolyte is not particularly limited, but may be less than or equal to about 5.0 wt%, less than or equal to about 3.0 wt%, less than or equal to about 1.0 wt%, less than or equal to about 0.5 wt%, or less than or equal to about 0.25 wt%.

[0038] For example, the content (e.g., amount) of the lanthanide metal imide salt in 100 wt% of the electrolyte may be about 0.05 to about 5.0 wt%, about 0.05 to about 3.0 wt%, about 0.05 to about 1.0 wt%, about 0.05 to about 0.5 wt%, or about 0.05 to about 0.25 wt%. When the above range is met, a suitable or appropriate level of lithium-philic film can be formed on the surface of the negative electrode, and the precipitate at the interface between the negative electrode and the electrolyte can be minimized or reduced. As a result, a rechargeable lithium battery having improved fast charging performance while suppressing or reducing the degradation of life cycle characteristics and / or suppressing or reducing the increase in resistance can be achieved.

[0039] Lanthanide metals constituting lanthanide metal imide salts

[0040] The lanthanide metal constituting the lanthanide metal imide salt may be lanthanum (La), cerium (Ce) and / or a combination thereof (e.g., any suitable combination thereof). Desirably, the lanthanide metal imide salt may be LaFSI (lanthanum bis(fluorosulfonyl)imide), LaTFSI (lanthanum (III) bis(trifluoromethanesulfonyl)imide), CeFSI (cerium bis(fluorosulfonyl)imide), CeTFSI (cerium bis(trifluoromethanesulfonyl)imide) and / or a combination thereof (e.g., any suitable combination thereof). More desirably, the lanthanide metal imide salt may be LaTFSI or CeTFSI among the four types (kinds) of compounds.

[0041] Non-aqueous organic solvent

[0042] In one or more embodiments, the non-aqueous organic solvent is used as a medium for transporting ions participating in the electrochemical reaction of the battery.

[0043] The non-aqueous organic solvent may include a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, an aprotic solvent, and / or combinations thereof (eg, any appropriate combination thereof).

[0044] Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, valerolactone, caprolactone, etc. Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and aprotic solvents may include nitriles (such as R-CN (wherein R is a C2-C20 straight chain, branched or cyclic hydrocarbon group, and may include a double bond, an aromatic ring or an ether group)), amides (such as dimethylformamide), dioxolanes (such as 1,3-dioxolane or 1,4-dioxolane), sulfolane, etc.

[0045] The nonaqueous organic solvent may be used alone or in combination of two or more.

[0046] In addition, if (for example, when) a carbonate-based solvent is used, a cyclic carbonate and a chain carbonate may be mixed and used, and the cyclic carbonate and the chain carbonate may be mixed in a volume ratio of about 1:1 to about 1:9.

[0047] In one or more embodiments, ethylene carbonate (EC) may be used as the cyclic carbonate, and ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) may be used as the chain carbonate.

[0048] In one or more embodiments, the nonaqueous organic solvent may be mixed and used in a volume ratio of EC:EMC:DMC=about 1:0.5:0.5 to about 1:4.5:4.5 to achieve excellent or appropriate electrolyte performance.

[0049] Lithium salts

[0050] The lithium salt dissolved in the non-aqueous organic solvent supplies lithium ions in the battery, ensures the basic operation of the rechargeable lithium battery, and improves the transport of lithium ions between the positive electrode and the negative electrode. Examples of lithium salts may include those selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, 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 of 1 to 20), one or more of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFOB) and lithium bis(oxalato)borate (LiBOB).

[0051] Other additives

[0052] The electrolyte may further include carbonate additives, sultone additives, nitrile additives, lithium salt additives and / or combinations thereof (eg, any appropriate combination thereof) to improve the life cycle of the battery.

[0053] The carbonate-based additive may include vinylene carbonate or ethylene carbonate-based compounds.

[0054] Examples of the ethylene carbonate-based compound may include fluoroethylene carbonate, difluoroethylene carbonate, vinylethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, and the like.

[0055] The nitrile additive may include a mononitrile compound, a dinitrile compound, a polynitrile compound, and / or combinations thereof (eg, any suitable combination thereof).

[0056] Examples of mononitrile compounds or dinitrile compounds may include succinonitrile (SN), glutaronitrile, adiponitrile (AN), pimelonitrile, suberonitrile, azelaic acid, caprylnitrile, ethylene glycol bis(propionitrile) ether (nitrile ether), fumaronitrile, and the like.

[0057] Examples of polynitrile compounds may include 1,3,6-hexanetricarbonitrile (HTCN), 1,2,6-hexanetricarbonitrile, 1,3,5-pentanetricarbonitrile, nonanetricarbonitrile, 1,3,5-benzotricarbonitrile, 2,4,6-trifluorobenzene-1,3,5-tricarbonitrile, 1,3,5-cyclohexanetricarbonitrile, 1,2,3-propanetricarbonitrile, 1,3,5-benzotricyano, 1,2,3-tris(2-cyanooxy)propane, and the like.

[0058] Sultone additives may include propylene sultone (PST), propane sultone (PS), etc.; lithium salt additives may include lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), lithium difluoro(fluoromalonate)borate (LFMB), etc.

[0059] Rechargeable lithium battery

[0060] One or more embodiments provide a rechargeable lithium battery including: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and the above-mentioned electrolyte.

[0061] By applying the above electrolyte, fast charging performance can be improved while minimizing or reducing degradation of life cycle characteristics and / or minimizing or reducing increase in resistance.

[0062] Hereinafter, a repeated description of the electrolyte may not be provided, and the rechargeable lithium battery will be described in more detail.

[0063] Positive electrode active material

[0064] The positive electrode active material may be a compound capable of intercalating and deintercalating lithium (lithiated intercalation compound). Desirably, a composite oxide of one or more types (species) of lithium and a metal selected from cobalt, manganese, nickel and / or a combination thereof (eg, any appropriate combination thereof) may be used.

[0065] The composite oxide may be a lithium transition metal composite oxide, and examples may include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free lithium nickel manganese-based oxides, and / or combinations thereof (eg, any appropriate combination thereof).

[0066] As an example, a compound represented by any one of the following chemical formulas can be used. a A 1-b X b O 2-c Dc (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05);Li a Mn 2-b X b About 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 About 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 About 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).

[0067] In the above chemical formula, A is Ni, Co, Mn and / or a combination thereof (e.g., any suitable combination thereof); X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element and / or a combination thereof (e.g., any suitable combination thereof); D is O, F, S, P and / or a combination thereof (e.g., any suitable combination thereof); G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and / or a combination thereof (e.g., any suitable combination thereof); and L 1 is Mn, Al, and / or combinations thereof (eg, any suitable combination thereof).

[0068] As an example, based on 100 mol% of the metal excluding lithium in the lithium transition metal composite oxide, the positive electrode active material may have a nickel content (e.g., amount) of greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol%, and in one or more embodiments, it may be a high nickel-based positive electrode active material having a nickel content (e.g., amount) of less than or equal to about 99 mol%. The high nickel-based positive electrode active material can achieve a relatively high capacity and can be applied to a relatively high capacity, relatively high energy density rechargeable lithium battery.

[0069] Desirably, the positive electrode active material may include one or more compounds represented by Chemical Formula 1.

[0070] Chemical formula 1

[0071] Li x M 1 y M 2 z M 3 1-y-z O2

[0072] In chemical formula 1, 0.5≤x≤1.8; 0 <y≤1;0≤z≤1;0≤y+z≤1;M 1 、M 2 and M 3 Each independently may be a metal selected from the group consisting of Ni, Co, Mn, Al, Sr, Mg, La, and combinations thereof (eg, any suitable combination thereof).

[0073] More expected, M 1 and M 2 may be Ni or Co independently, and M 3 M may be a metal such as Mn, Al, Sr, Mg or La. Even more desirably, M 1 and M 2 may be Ni or Co independently, and M 3It may be Mn or Al.

[0074] In one or more embodiments, x may satisfy 1 ≤ x ≤ 1.2. Additionally, y may satisfy 0.5 ≤ y < 1, 0.6 ≤ y < 1, or 0.7 ≤ y < 1. In one or more embodiments, z may satisfy 0 < z ≤ 0.5, 0 < z ≤ 0.3, or 0 < z ≤ 0.2.

[0075] For example, M 1 and M 2 may be Ni and Co respectively, M 3 may be Mn or Al, and 1 ≤ x ≤ 1.2, 0.7 ≤ y < 1, and 0 < z ≤ 0.3. For example, the positive electrode active material may be a high-nickel (high Ni) nickel cobalt manganese (NCM) compound or a nickel cobalt aluminum (NCA) compound.

[0076] When the positive electrode active material is a high-nickel (high Ni) NCA compound or an NCM compound, it may be a compound represented by Chemical Formula 1-1 or Chemical Formula 1-2.

[0077] Chemical Formula 1-1

[0078] Li x1 Ni y1 Co z1 Al 1-y1-z1 O2

[0079] In Chemical Formula 1-1, 1 ≤ x1 ≤ 1.2; 0.7 ≤ y1 ≤ 1; 0 ≤ z1 ≤ 0.3; and 0.7 ≤ y1 + z1 ≤ 1.

[0080] Chemical Formula 1-2

[0081] Li x2 Ni y2 Co z2 Mn 1-y2-z2 O2

[0082] Wherein, in Chemical Formula 1-2, 1 ≤ x1 ≤ 1.2; 0.7 ≤ y2 ≤ 1; 0 ≤ z2 ≤ 0.3; and 0.7 ≤ y2 + z2 ≤ 1.

[0083] Positive electrode

[0084] The positive electrode for a rechargeable lithium battery may include a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector. The positive electrode active material layer may include a positive electrode active material and may further include a binder and / or a conductive material.

[0085] For example, the positive electrode may further include an additive that can be used as a sacrificial positive electrode.

[0086] The content (eg, amount) of the positive electrode active material may be about 90 wt % to about 99 wt % based on 100 wt % of the positive electrode active material layer, and the content (eg, amount) of the binder and the conductive material may each be about 0.5 wt % to about 5 wt %.

[0087] The binder is used to attach or fix the positive electrode active material particles to each other, and also to attach the positive electrode active material to the positive electrode current collector. Examples of binders may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth) acrylated styrene-butadiene rubber, epoxy resin, (meth) acrylic resin, polyester resin, nylon, etc. as non-limiting examples.

[0088] Conductive materials can be used to impart conductivity (e.g., electrical conductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used as the conductive material in the battery. Examples of conductive materials may include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; and / or (e.g., any appropriate) mixtures thereof.

[0089] Al foil may be used as a positive electrode current collector, but the present disclosure is not limited thereto.

[0090] Negative electrode active material

[0091] The negative electrode active material may be a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, and / or a transition metal oxide.

[0092] The material that reversibly intercalates / deintercalates lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, and / or a combination thereof (e.g., any suitable combination thereof). The crystalline carbon may be graphite, such as amorphous, flaky (e.g., in the shape of a sheet), flake (e.g., in the shape of a flake), spherical (e.g., in the shape of a sphere), or fibrous (e.g., in the shape of a fiber) natural graphite or artificial graphite. The amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbide (e.g., coal pitch), calcined coke, etc.

[0093] The lithium metal alloy may include 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.

[0094] The material capable of doping / dedoping lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite (Si-C composite), SiO x (0 < x ≤ 2), a Si-Q alloy (where 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 / or combinations thereof (e.g., any suitable combination thereof)). The Sn-based negative electrode active material may include Sn, SnO x (0 < x ≤ 2) (e.g., SnO2), Sn-based alloys, and / or combinations thereof (e.g., any suitable combination thereof).

[0095] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one or more embodiments, 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, the silicon-carbon composite may include secondary particles (cores) in which primary silicon particles are assembled (e.g., aggregated) and an amorphous carbon coating (shell) on the surface of the secondary particles. Amorphous carbon may also be present between the primary silicon particles, and, for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0096] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include: a core including crystalline carbon and silicon particles; and an amorphous carbon coating on the surface of the core.

[0097] The Si-based negative electrode active material or the Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material.

[0098] Negative electrode

[0099] The negative electrode for a rechargeable lithium battery includes a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material.

[0100] For example, based on 100 wt% of the negative electrode active material layer, the negative electrode active material layer may include about 90 wt% to about 99 wt% of the negative electrode active material, about 0.5 wt% to about 5 wt% of the binder, and about 0 wt% to about 5 wt% of the conductive material.

[0101] The binder can be used to attach the negative electrode active material particles to each other and also attach the negative electrode active material to the negative electrode current collector. The binder can include a non-aqueous binder, an aqueous binder, a dry binder, and / or a combination thereof (eg, any suitable combination thereof).

[0102] The non-aqueous binder may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, and / or combinations thereof (eg, any suitable combination thereof).

[0103] The aqueous binder can be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol and / or combinations thereof (e.g., any suitable combination thereof).

[0104] When the aqueous binder is used as a binder in the negative electrode active material layer, it may further include a cellulose compound capable of imparting viscosity. The cellulose compound includes one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose and alkali metal salts thereof. The alkali metal may be Na, K or Li.

[0105] The dry binder may be a polymer material capable of fiberization, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and / or combinations thereof (eg, any appropriate combination thereof).

[0106] A conductive material is included to provide electrode conductivity, and any conductive material can be used as the conductive material unless it causes a chemical change. Examples of the conductive material may be carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; and / or (e.g., any appropriate) mixtures thereof.

[0107] The negative electrode current collector may include one selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and / or combinations thereof (eg, any appropriate combination thereof), but the present disclosure is not limited thereto.

[0108] Diaphragm

[0109] Depending on the type or kind of the rechargeable lithium battery, the separator may be present between the positive electrode and the negative electrode. The separator may include a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multilayer film of two or more layers thereof (such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, etc.).

[0110] The membrane may include a porous substrate and a coating located on a surface of the porous substrate (e.g., on one surface or both surfaces or on one side or both sides (e.g., on opposite surfaces)), the coating including an organic material, an inorganic material and / or a combination thereof (e.g., any suitable combination thereof).

[0111] The porous substrate may be a polymer film formed of any one or more polymers selected from polyolefins (such as polyethylene and / or polypropylene), polyesters (such as polyethylene terephthalate and / or polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyetherketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene ethers, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers and / or polytetrafluoroethylene (PTFE, e.g., Teflon), or may be a polymer film formed of a copolymer or (e.g., any appropriate) mixture of two or more thereof.

[0112] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acryl-based polymer.

[0113] The inorganic material may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite and / or combinations thereof (e.g., any suitable combination thereof), but the present disclosure is not limited thereto.

[0114] An organic material and an inorganic material may be mixed in one coating layer, or a coating layer including an organic material and a coating layer including an inorganic material may be laminated.

[0115] Rechargeable lithium battery

[0116] Rechargeable lithium batteries may be classified into cylindrical batteries, prismatic batteries, pouch-type (or kind) batteries, coin-type (or kind) batteries, etc. according to their shapes. Figure 1 A schematic diagram showing a cylindrical rechargeable lithium battery according to one or more embodiments of the present disclosure. Figure 1, the rechargeable lithium battery 100 may include: an electrode assembly including a positive electrode 10, a negative electrode 20, and a separator 30 between the positive electrode 10 and the negative electrode 20; and a case 50 in which the electrode assembly is accommodated. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte (not shown), and may include a sealing member 60 that seals the case 50.

[0117] The rechargeable lithium battery according to one or more embodiments may be applied to automobiles, mobile phones, and / or one or more appropriate types (kinds) of electrical devices, but the present disclosure is not limited thereto.

[0118] Hereinafter, embodiments and comparative examples of the present disclosure are described. However, these examples are not to be construed as limiting the scope of the present disclosure in any sense.

[0119] Preparation of electrolyte for rechargeable lithium batteries

[0120] Preparation Example 1

[0121] As the nonaqueous organic solvent, a carbonate-based solvent prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 20:40:40 was used.

[0122] 1.5 M of lithium salt (LiPF6) is added to a non-aqueous organic solvent, and 0.05 wt % of a lanthanide metal imide salt (lanthanum (III) bis(trifluoromethanesulfonyl)imide (LaTFSI)) as an additive, 1.5 wt % of vinylene carbonate (VC) and 0.5 wt % of vinyl ethylene carbonate (VEC) as other additives are added thereto to obtain an electrolyte for a rechargeable lithium battery.

[0123] Herein, the content (eg, amount) (wt%) of the lanthanide metal imide salt indicates the content (eg, amount) (wt%) of the lanthanide metal imide salt based on 100 wt% of the electrolyte for a rechargeable lithium battery.

[0124] Preparation Example 2

[0125] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as Preparation Example 1, except that 0.1 wt % of a lanthanide metal imide salt (LaTFSI) was used as an additive.

[0126] Preparation Example 3

[0127] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as Preparation Example 1, except that 0.25 wt % of a lanthanide metal imide salt (LaTFSI) was used as an additive.

[0128] Preparation Example 4

[0129] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as Preparation Example 1, except that 0.5 wt % of a lanthanide metal imide salt (LaTFSI) was used as an additive.

[0130] Preparation Example 5

[0131] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as Preparation Example 1, except that 1.0 wt % of a lanthanide metal imide salt (LaTFSI) was used as an additive.

[0132] Preparation Example 6

[0133] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as Preparation Example 1, except that 5.0 wt % of a lanthanide metal imide salt (LaTFSI) was used as an additive.

[0134] Preparation Example 7

[0135] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as Preparation Example 1, except that 0.25 wt % of a lanthanide metal imide salt (CeFSI) was used as an additive.

[0136] Preparation Example 8

[0137] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as Preparation Example 1, except that 0.25 wt % of a lanthanide metal imide salt (CeTFSI) was used as an additive.

[0138] Comparative Preparation Example 1

[0139] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as in Preparation Example 1, except that no additive was added.

[0140] Comparative Preparation Example 2

[0141] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as in Preparation Example 1, except that 0.25 wt % of a lanthanide metal nitrate (La(NO 3 ) 3 ) was used as an additive.

[0142] Comparative Preparation Example 3

[0143] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as in Preparation Example 1, except that 0.25 wt % of a lanthanide metal phosphate (LaPF 6 ) was used as an additive.

[0144] Comparative Preparation Example 4

[0145] An electrolyte for a rechargeable lithium battery was prepared in substantially the same manner as in Preparation Example 1, except that 1.0 M LiPF6 and 0.5 M lanthanide metal imide salt (LaTFSI) were used instead of 1.5 M lithium salt (LiPF6), and vinylene carbonate (VC) and vinyl ethylene carbonate (VEC) were not added as other additives.

[0146] Manufacturing of rechargeable lithium battery cells

[0147] Example 1

[0148] LiNi as the positive electrode active material 0.88 Co 0.07 Al 0.05 O2, polyvinylidene fluoride as a binder, and Ketjen black as a conductive material were mixed in a weight ratio of 97:2:1 and then dispersed in N-methylpyrrolidone to prepare a positive electrode active material slurry.

[0149] The positive electrode active material slurry was coated on a 14 μm thick Al foil, dried at 110° C., and pressed to produce a positive electrode.

[0150] A mixture of artificial graphite and Si—C composite at a weight ratio of 93:7 was prepared as a negative electrode active material, and the negative electrode active material, styrene-butadiene rubber, and carboxymethyl cellulose at a weight ratio of 97:1:2 were dispersed in distilled water to prepare a negative electrode active material slurry.

[0151] The Si-C composite includes: a core including artificial graphite and silicon particles; and coal tar pitch coated on a surface of the core.

[0152] The negative electrode active material slurry was coated on a 10 μm-thick Cu foil, dried at 100° C., and pressed to manufacture a negative electrode.

[0153] The manufactured positive and negative electrodes and a polyethylene separator having a thickness of 25 μm were assembled to manufacture an electrode assembly, and the electrolyte for a rechargeable lithium battery of Preparation Example 1 was injected to manufacture a rechargeable lithium battery cell.

[0154] Example 2

[0155] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Preparation Example 2 was injected.

[0156] Example 3

[0157] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Preparation Example 3 was injected.

[0158] Example 4

[0159] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Preparation Example 4 was injected.

[0160] Example 5

[0161] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Preparation Example 5 was injected.

[0162] Example 6

[0163] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Preparation Example 6 was injected.

[0164] Example 7

[0165] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Preparation Example 7 was injected.

[0166] Example 8

[0167] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Preparation Example 8 was injected.

[0168] Comparative Example 1

[0169] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Comparative Preparation Example 1 was injected.

[0170] Comparative Example 2

[0171] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Comparative Preparation Example 2 was injected.

[0172] Comparative Example 3

[0173] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Comparative Preparation Example 3 was injected.

[0174] Comparative Example 4

[0175] A rechargeable lithium battery cell was prepared in substantially the same manner as in Example 1, except that the electrolyte for a rechargeable lithium battery according to Comparative Preparation Example 4 was injected.

[0176] Evaluation Example

[0177] Evaluation 1: Precipitation at the interface between the negative electrode and the electrolyte

[0178] Each of the rechargeable lithium battery cells according to Examples 1 to 8 and Comparative Examples 1 to 4 was charged to 80% state of charge (SOC) at 1C constant current (CC) and discharged at 0.1C, and then the amount of lithium dendrite precipitation was measured according to Equation 1, and the results are shown in Table 1.

[0179] Equation 1

[0180] Lithium dendrite precipitation amount (%) = 100 × (amount of lithium dendrites after discharge under the above conditions / amount of lithium dendrites after charging at SOC 80%)

[0181] Table 1

[0182] Lithium dendrite precipitation amount [%] Comparative Example 1 1.53 Comparative Example 2 1.50 Comparative Example 3 1.49 Comparative Example 4 2.8 Example 1 1.32 Example 2 1.23 Example 3 1.18 Example 4 1.22 Example 5 1.25 Example 6 1.30 Example 7 1.17 Example 8 1.21

[0183] Referring to Table 1, Examples 1 to 8 each had suppressed or reduced lithium dendrite precipitation at the interface between the negative electrode and the electrolyte, compared to Comparative Examples 1 to 4.

[0184] Evaluation 2: Capacity retention and DC-IR increase rate during fast charging

[0185] The life cycle characteristics (capacity retention rate after 300 rapid charge cycles) and the DC internal resistance (DC-IR) increase rate of each of the rechargeable lithium battery cells according to Examples 1 to 8 and Comparative Examples 1 to 4 were measured, and the results are shown in Table 2.

[0186] The rechargeable lithium battery cells were rapidly charged once at a rate in the range of 2.0 C to 3.0 C at 25° C. to a voltage of 4.2 V, and then discharged at a rate of 0.5 C to a voltage of 2.8 V. This cycle was repeated 300 times with a 10-minute pause after each cycle.

[0187] After repeating 300 cycles, the capacity retention rate of the battery cell was evaluated according to Equation 2, and the DC-IR growth rate of the battery cell was also evaluated according to Equation 3:

[0188] Equation 2

[0189] Capacity retention rate (%) = [discharge capacity after 300th cycle / discharge capacity after 1st cycle] × 100

[0190] Equation 3

[0191] DC-IR increase rate = DC-IR (300th charge / discharge cycle) / DC-IR (0th day)

[0192] In Equation 3, DC-IR(300th charge / discharge cycle) indicates DC-IR after the 300th charge / discharge cycle at 25° C., and DC-IR(day 0) indicates DC-IR before 300 charge / discharge cycles.

[0193] Table 2

[0194]

[0195] Referring to Table 2, Examples 1 to 8 had suppressed or reduced resistance increase during rapid charging compared to Comparative Examples 1 to 4, which confirmed that the life cycle thereof was improved during rapid charging.

[0196] Assessment 3: Fast charging time

[0197] The rapid charging time of the rechargeable lithium battery cells of Examples 1 to 8 and Comparative Examples 1 to 4 was evaluated under the following conditions, and the results are shown in Table 3.

[0198] The fast charge time is obtained by measuring the time taken to fully charge each battery cell to 4.2 V (SOC 100%) or to reach SOC 80% when charged at a current CC of 1.0 C at 25°C.

[0199] Table 3

[0200]

[0201]

[0202] Taking Table 1 and Table 3 into consideration, Examples 1 to 8 each have suppressed or reduced lithium dendrite precipitation at the interface between the negative electrode and the electrolyte compared to Comparative Examples 1 to 4, which should contribute positively to the improvement of fast charging.

[0203] Unless otherwise defined, all terms (including technical and scientific terms) used in this article have the same meaning as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. It will be further understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant field and / or this specification, and should not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0204] Additionally, when describing embodiments of the present disclosure, the use of “may” refers to “one or more embodiments of the present disclosure.”

[0205] As used herein, the terms "substantially," "about," and the like are used as terms of approximation and not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values ​​that one of ordinary skill in the art will recognize. As used herein, the term "substantially" includes the stated value and means within an acceptable range of deviations of the particular value determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "substantially" may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0206] Furthermore, any numerical range set forth herein is intended to include all sub-ranges of the same numerical precision falling within the range set forth. For example, the range of "1.0 to 10.0" is intended to include between the minimum value 1.0 set forth and the maximum value 10.0 set forth (and including 1.0 and 10.0), that is, all sub-ranges with a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limit set forth herein is intended to include all lower numerical limits falling therein, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits falling therein. Accordingly, the applicant reserves the right to modify this specification (including claims) to explicitly set forth any sub-range falling within the range explicitly set forth herein.

[0207] The portable device, vehicle, battery (e.g., battery controller) and / or any other related device or component according to the embodiments of the present disclosure described herein may be implemented using any appropriate hardware, firmware (e.g., application specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of the device may be formed on an integrated circuit (IC) chip or on a separate IC chip. In addition, the various components of the device may be implemented on a flexible printed circuit film, a tape carrier package (TCP), or a printed circuit board (PCB), or formed on a substrate. In addition, the various components of the device may be processes or threads running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components to perform the various functions described herein. The computer program instructions are stored in a memory, which may be implemented in a computing device using a standard memory device, such as, for example, a random access memory (RAM). The computer program instructions may also be stored in other non-temporary computer-readable media, such as, for example, a CD-ROM or a flash drive, etc. Moreover, it should be recognized by those skilled in the art that the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a dedicated computing device may be distributed on one or more other computing devices without departing from the scope of the embodiments of the present disclosure.

[0208] Although the embodiments of the present disclosure have been described, it should be understood that the present disclosure should not be limited to these embodiments, but a person skilled in the art may make one or more appropriate changes and modifications within the spirit and scope of the present disclosure defined by the claims and their equivalents.

Claims

1. An electrolyte comprising: Non-aqueous organic solvents; Lithium salts; and Lanthanide metal imide salts. 2 . The electrolyte according to claim 1 , wherein the amount of the lanthanide metal imide salt is 0.05 to 5 wt % based on 100 wt % of the electrolyte. 3 . The electrolyte according to claim 2 , wherein the amount of the lanthanide metal imide salt is 0.05 to 0.25 wt % based on 100 wt % of the electrolyte. 4 . The electrolyte of claim 1 , wherein the lanthanide metal of the lanthanide metal imide salt is lanthanum, cerium or a combination thereof.

5. The electrolyte of claim 1, wherein the lanthanide metal imide salt is lanthanum bis(fluorosulfonyl)imide, lanthanum (III) bis(trifluoromethanesulfonyl)imide, cerium bis(fluorosulfonyl)imide, cerium bis(trifluoromethanesulfonyl)imide and / or a combination thereof. 6 . The electrolyte according to claim 1 , wherein the non-aqueous organic solvent comprises a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent and / or an aprotic solvent. 7 . The electrolyte according to claim 6 , wherein the non-aqueous organic solvent comprises the carbonate-based solvent, wherein a cyclic carbonate and a chain carbonate are mixed in a volume ratio of 1:1 to 1:

9.

8. The electrolyte according to claim 7, wherein The cyclic carbonate comprises ethylene carbonate, and The chain carbonates include ethyl methyl carbonate and dimethyl carbonate.

9. The electrolyte according to claim 1, wherein The lithium salt includes a salt selected from the group consisting of LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, LiC4F9SO3, LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2), one or more of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate and lithium bis(oxalato)borate, wherein x and y are integers of 1 to 20. 10 . The electrolyte according to claim 9 , wherein the concentration of the lithium salt in the electrolyte is 1.0 M to 2.0 M.

11. A rechargeable lithium battery comprising: a positive electrode, including a positive electrode active material; a negative electrode, including a negative electrode active material; as well as The electrolyte according to any one of claims 1 to 10.

12. The rechargeable lithium battery of claim 11, wherein the positive electrode active material comprises one or more compounds represented by Chemical Formula 1: Chemical formula 1 Li x M 1 y M 2 z M 3 1-y-z O2 in, In Chemical Formula 1, 0.5 ≤ x ≤ 1.8; 0 < y ≤ 1; 0 ≤ z ≤ 1; 0 ≤ y + z ≤ 1; and M 1 , M 2 and M 3 are each independently selected from the following metals: selected from Ni, Co, Mn, Al, Sr, Mg, La, and combinations thereof.

13. The rechargeable lithium battery of claim 12, wherein the positive electrode active material is a compound represented by Chemical Formula 1-1 or Chemical Formula 1-2: Chemical formula 1-1 Li x1 Ni y1 Co z1 Al 1-y1-z1 O2, In Chemical Formula 1-1, 1≤x1≤1.2; 0.7≤y1≤1; 0≤z1≤0.3; and 0.7≤y1+z1≤1, Chemical formula 1-2 Li x2 Ni y2 Co z2 Mr 1-y2-z2 O2, In Chemical Formula 1-2, 1≤x1≤1.2; 0.7≤y2≤1; 0≤z2≤0.3; and 0.7≤y2+z2≤1. 14 . The rechargeable lithium battery of claim 11 , wherein the negative electrode active material comprises a Si-based negative electrode active material.

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