Rechargeable lithium battery

Abstract

The invention relates to a rechargeable lithium battery. A rechargeable lithium battery includes: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte, in which the active mass density of the negative electrode is greater than or equal to about 1.7 g / cc, and the electrolyte includes: a lithium salt; a non-aqueous organic solvent; and an additive represented by Chemical Formula 1: The description of Chemical Formula 1 # imgabs0 # Chemical Formula follows the specification.

Description

Technical Field

[0001] The present disclosure herein relates to rechargeable lithium batteries. Background Art

[0002] Recently, with the rapid popularization (and / or development) of electronic devices using batteries (such as mobile phones, laptop computers and / or electric vehicles), the demand for rechargeable batteries with relatively high energy density and relatively high capacity is rapidly increasing. Accordingly, research and development to improve the performance of rechargeable lithium batteries is being actively conducted (e.g., in progress) or pursued.

[0003] A rechargeable lithium battery includes a positive electrode, a negative electrode, and an electrolyte, and the positive electrode and the negative electrode each include an active material capable of inserting / extracting lithium ions. If (for example, when) lithium ions are inserted / extracted from the positive electrode and the negative electrode, electrical energy is generated through oxidation and reduction reactions.

[0004] One of the latest development directions of rechargeable lithium batteries is to increase the active mass density of the negative electrode. However, if (e.g., when) the active mass density of the negative electrode increases, the void volume decreases, which increases the amount of electrolyte impregnated into the negative electrode, causing the battery thickness to increase and the cycle life to decrease. Summary of the invention

[0005] Aspects according to some embodiments relate to a rechargeable lithium battery that may have an increased active mass density of a negative electrode and effectively suppress an increase in battery thickness and a decrease in cycle life.

[0006] 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 embodiments presented in the disclosure.

[0007] According to some embodiments, a rechargeable lithium battery includes: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte, wherein the active mass density of the negative electrode is greater than or equal to about 1.7 g / cc, and the electrolyte includes: a lithium salt; a non-aqueous organic solvent; and an additive represented by Chemical Formula 1:

[0008] Chemical formula 1

[0009]

[0010] A rechargeable lithium battery according to some embodiments may have an increased active mass density of a negative electrode while suppressing or reducing an increase in battery thickness and a decrease in cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The attached drawings are included to provide a further understanding of the present disclosure and are incorporated into and constitute a part of this specification. The drawings illustrate embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. In the drawings:

[0012] Figure 1 A schematic diagram illustrating a cylindrical battery according to some embodiments.

[0013] Figure 2 A schematic diagram illustrating a prismatic battery according to some embodiments.

[0014] Figure 3 A schematic diagram illustrating a pouch-type or similar battery according to some embodiments.

[0015] Figure 4 A schematic diagram illustrating a pouch-type or similar battery according to some embodiments.

[0016] Description of Reference Numerals

[0017] 100: Rechargeable lithium battery 10: Positive electrode

[0018] 11: Positive electrode lead lug 12: Positive electrode terminal

[0019] 20: Negative electrode 21: Negative electrode lead lug

[0020] 22: Negative electrode terminal 30: Separator

[0021] 40: electrode assembly 50: shell

[0022] 60: Sealing member 70: Electrode terminal piece

[0023] 71: Positive electrode terminal tab 72: Negative electrode terminal tab DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described in more detail. However, these embodiments are examples, the present disclosure is not limited thereto, and the scope of the present disclosure is defined by the claims and their equivalents.

[0025] As used herein, if (for example, when) no specific definition is provided otherwise, it will be understood that if (for example, when) an element (such as a layer, film, region or substrate) is referred to as being "on" another element (such as a layer, film, region or substrate), it can be directly on the other element (such as a layer, film, region or substrate) or intervening elements may also be present.

[0026] As used herein, if (for example, when) no specific definition is provided otherwise, a singular expression may also include a plural expression. In addition, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B".

[0027] As used herein, "combinations thereof" may refer to mixtures, stacks, composites, copolymers, alloys, blends, and / or reaction products of the components.

[0028] As used herein, “active mass density of the negative electrode” refers to a value calculated by dividing the weight of components (active material, conductive material, binder, etc.) in the negative electrode excluding the negative electrode current collector by its volume.

[0029] As used herein, if (eg, when) no definition is otherwise provided, in a chemical formula, if (eg, when) a chemical bond should be given but is not drawn, then a hydrogen atom is bonded to that position.

[0030] As used herein, "fluoroalkyl" refers to an alkyl group in which one or more or all of the hydrogen atoms are replaced by fluorine atoms.

[0031] As used herein, "perfluoroalkyl" refers to an alkyl group in which all hydrogen atoms are replaced by fluorine atoms.

[0032] Rechargeable lithium battery

[0033] According to some embodiments, a rechargeable lithium battery includes: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte, wherein the active mass density of the negative electrode is greater than or equal to about 1.7 g / cc, and the electrolyte includes: a lithium salt; a non-aqueous organic solvent; and an additive represented by Chemical Formula 1:

[0034] Chemical formula 1

[0035]

[0036] The additive may function as a surfactant having both a hydrophilic group and a hydrophobic group in one molecule (eg, having both a hydrophilic group and a hydrophobic group).

[0037] The additive includes a keto group at the center and fluorine atoms and / or C1-C10 fluoroalkyl groups at both sides (eg, opposite sides) of the keto group. Herein, the keto group is a hydrophilic group, and the fluorine atoms or C1-C10 fluoroalkyl groups are hydrophobic groups.

[0038] Accordingly, if (for example, when) an electrolyte including the additive is used, wettability of the positive electrode and the negative electrode can be improved, and lithium cations (Li ions) can be uniformly (substantially uniformly) formed at the interface between the positive electrode and the electrolyte. + ), and a stable SEI film can be formed at the interface between the negative electrode and the electrolyte, thereby inhibiting or reducing the precipitation of lithium dendrites.

[0039] Therefore, if (for example, when) an electrolyte including the additive is used, while the active mass density of the negative electrode can be increased to 1.7 g / cc or more, an increase in battery thickness and a decrease in cycle life can be suppressed or reduced.

[0040] Hereinafter, a rechargeable lithium battery according to some embodiments will be described in more detail.

[0041] Active mass density of negative electrode

[0042] Typically known rechargeable lithium batteries use a negative electrode having an active mass density of less than about 1.7 g / cc, but rechargeable lithium batteries according to some embodiments use a negative electrode having an active mass density greater than or equal to (eg, at least) about 1.7 g / cc.

[0043] The upper limit of the active mass density of the negative electrode is not particularly limited, but may be less than or equal to about 2.0 g / cc, less than or equal to about 1.9 g / cc, or less than or equal to about 1.8 g / cc.

[0044] Charging upper limit voltage

[0045] In a rechargeable lithium battery according to some embodiments, by using an electrolyte including an additive, an increase in battery thickness and a decrease in cycle life can be suppressed or reduced even if (for example, when) the negative electrode increases in active mass density (for example, the active mass density of the negative electrode increases).

[0046] For example, a rechargeable lithium battery may have a charge upper limit voltage greater than or equal to about 4.4V.

[0047] additive

[0048] In Chemical Formula 1, R 1 and R 2 Each independently may be a fluorine atom or a C1-C10 fluoroalkyl group.

[0049] In some embodiments, R 1 It may be a fluoroalkyl group having 2 carbon atoms, for example, a perfluoroalkyl group having 2 carbon atoms.

[0050] In some embodiments, R 2 It may be a fluoroalkyl group having 3 carbon atoms, for example, a perfluoroalkyl group having 3 carbon atoms.

[0051] The additive can be represented by chemical formula 1-1:

[0052] Chemical formula 1-1

[0053]

[0054] In Chemical Formula 1-1, R 11 ~R 15 may be independently a hydrogen atom or a fluorine atom, provided that R 11 ~R 15 At least one of (for example, selected from R 11 ~R 15 At least one of ) is a fluorine atom; and R 21 ~R 27 may be independently a hydrogen atom or a fluorine atom, provided that R 21 ~R 27 At least one of (for example, selected from R 21 ~R 27 At least one of the above) is a fluorine atom.

[0055] An example of the additive is represented by Chemical Formula 1-1-1:

[0056] Chemical formula 1-1-1

[0057]

[0058] Content of additives

[0059] The additive may be included in an amount of about 0.5 wt % to about 10 wt %, about 0.5 wt % to about 5 wt %, or about 0.5 wt % to about 2 wt %, based on the total amount of the electrolyte.

[0060] If (for example, when) the additive is included in an amount greater than (for example, exceeding) the above range, the viscosity of the electrolyte including the additive may be excessively increased, and the wettability of the positive electrode and the negative electrode may actually decrease. On the other hand, if (for example, when) the additive is included in an amount smaller than the above range, the effect as a surfactant may be minimal or insufficient.

[0061] Non-aqueous organic solvent

[0062] The nonaqueous organic solvent serves as a medium for transferring (eg, transporting) ions participating in an electrochemical reaction of a rechargeable lithium battery.

[0063] The non-aqueous organic solvent may be a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent, an aprotic solvent, and / or a combination thereof (eg, any appropriate combination).

[0064] 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, propionate solvents (methyl propionate, ethyl propionate, propyl propionate (PP)), decanoic acid lactone, mevalonolactone, valerolactone, caprolactone, etc.

[0065] Ether solvents may include dibutyl ether, tetraglyme, diglyme, 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, where R is a C2-C20 straight chain hydrocarbon group, a branched hydrocarbon group, or a 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 and / or 1,4-dioxolane), sulfolane, etc.

[0066] The nonaqueous organic solvent may be used alone or in any combination of two or more.

[0067] In the latter case, the nonaqueous organic solvent may include carbonate-based solvents and propionate-based solvents.

[0068] The propionate-based solvent may be included in an amount greater than or equal to about 70% by volume based on the total amount of the non-aqueous organic solvent. In this case, high voltage and / or high temperature characteristics of a rechargeable lithium battery may be improved.

[0069] For example, the nonaqueous organic solvent may be a mixed solvent of ethylene carbonate (EC), propylene carbonate (PC), and propyl propionate (PP).

[0070] Lithium salts

[0071] The lithium salt dissolved in the nonaqueous organic solvent supplies lithium ions in the rechargeable lithium battery, ensures basic operations of the rechargeable lithium battery, and improves the transfer of lithium ions between the positive electrode and the negative electrode.

[0072] In some embodiments, LiPF6 may be used as the lithium salt.

[0073] The concentration of the lithium salt may be about 0.1M to about 2.0M.

[0074] Positive electrode active material

[0075] The positive electrode active material may be a compound capable of intercalating / deintercalating lithium ions (lithiated intercalation compound). For example, a composite oxide of one or more types (species) of lithium and a metal selected from cobalt, manganese, nickel, and a combination thereof may be used.

[0076] The composite oxide may be a lithium transition metal composite oxide, and specific examples may include lithium nickel composite oxides, lithium cobalt composite oxides, lithium manganese composite oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese composite oxides and / or combinations thereof (e.g., any appropriate combination).

[0077] 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 NeG 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 bO2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 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).

[0078] In the above chemical formula, A is Ni, Co, Mn and / or a combination thereof (e.g., any suitable combination); 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); D is O, F, S, P and / or a combination thereof (e.g., any suitable combination); G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and / or a combination thereof (e.g., any suitable combination); and L 1 is Mn, Al, and / or combinations thereof (eg, any suitable combination).

[0079] As an example, based on 100 mol% of metals 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 may be a high nickel-based positive electrode active material having less than or equal to about 99 mol% of nickel. The high nickel-based positive electrode active material can achieve high capacity and can be applied to high capacity, high density rechargeable lithium batteries.

[0080] The positive electrode active material may be, for example, a lithium nickel-based composite oxide represented by Chemical Formula 11, a lithium cobalt-based composite oxide represented by Chemical Formula 12, a lithium iron phosphate-based compound represented by Chemical Formula 13, a cobalt-free lithium nickel manganese-based composite oxide represented by Chemical Formula 14, and / or a combination thereof (for example, any appropriate combination).

[0081] Chemical formula 11

[0082] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0083] In 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, M 1 and M 2 Each of the above elements may be 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 may be one or more elements selected from the group consisting of F, P and S.

[0084] In Chemical Formula 11, in an embodiment, 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.

[0085] Chemical formula 12

[0086] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0087] In 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, M 3 It may be one or more elements selected from 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 may be one or more elements selected from F, P and S.

[0088] Chemical formula 13

[0089] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0090] In Chemical Formula 13, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.4, 0.9≤x3+y3≤1.1 and 0≤b3≤0.1, M 4 It may be one or more elements selected from 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 may be one or more elements selected from F, P and S.

[0091] Chemical Formula 14

[0092] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0093] In 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, and 0 ≤ b4 ≤ 0.1. M 5 may be one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X may be one or more elements selected from F, P, and S.

[0094] The electrolyte of the above embodiment can significantly improve the high voltage and / or high temperature characteristics of a rechargeable lithium battery using a lithium cobalt composite oxide represented by Chemical Formula 12.

[0095] Positive Electrode

[0096] 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.

[0097] For example, the positive electrode may further include an additive that can be used as a sacrificial positive electrode.

[0098] Based on 100 wt% of the positive electrode active material layer, the content (e.g., amount) of the positive electrode active material may be about 90 wt% to about 99 wt%, and the contents (e.g., amounts) of the binder and the conductive material may each independently be about 0.5 wt% to about 5 wt%.

[0099] The binder is used to appropriately (e.g., well) attach the positive electrode active material particles to each other and is also used to appropriately (e.g., well) attach the positive electrode active material to the positive electrode current collector. Non-limiting examples of the binder may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer including 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.

[0100] Conductive materials can be used to impart electrical conductivity (e.g., electroconductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesired chemical changes in a rechargeable lithium battery) and conducts electrons can be used in a rechargeable lithium battery. Examples of conductive materials can include carbonaceous materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and / or carbon nanotube); metallic materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers (such as polyphenylene derivatives); or mixtures thereof.

[0101] In some embodiments, Al foil can be used as the positive electrode current collector, but the present disclosure is not limited thereto.

[0102] Negative electrode active material

[0103] The negative electrode active material can 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.

[0104] Materials that reversibly intercalate / deintercalate lithium ions can include carbonaceous negative electrode active materials, e.g., crystalline carbon, amorphous carbon, and / or combinations thereof (e.g., any suitable combination). Crystalline carbon can be graphite (such as amorphous (e.g., irregularly shaped), flaky, sheet-like, spherical, or fibrous natural graphite or artificial graphite). Amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbonized product, calcined coke, etc.

[0105] Lithium metal alloys can include lithium and metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0106] Materials capable of doping / dedoping lithium can be Si-based negative electrode active materials or Sn-based negative electrode active materials. Si-based negative electrode active materials can include silicon, silicon-carbon composites, SiO x (0 < x ≤ 2), Si-Q alloys (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)). Sn-based negative electrode active materials can include Sn, SnO x (0 < x ≤ 2) (e.g., SnO2), Sn-based alloys, and / or combinations thereof (e.g., any suitable combination).

[0107] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to some 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 and an amorphous carbon coating (shell) on the surface of the secondary particles. Amorphous carbon is also between primary silicon particles, and, for example, primary silicon particles may be coated with amorphous carbon. Secondary particles may be dispersed in an amorphous carbon matrix.

[0108] 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.

[0109] The Si-based negative electrode active material or the Sn-based negative electrode active material may be used in combination with the carbon-based negative electrode active material.

[0110] Negative electrode

[0111] 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.

[0112] For example, 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.

[0113] The binder can be used to properly (e.g., well) attach the negative electrode active material particles to each other, and also to properly (e.g., well) attach the negative electrode active material to the negative electrode current collector. The binder may include a non-aqueous binder, an aqueous binder, a dry binder, and / or a combination thereof (e.g., any suitable combination).

[0114] 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).

[0115] 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, phenolic resin, epoxy resin, polyvinyl alcohol and / or combinations thereof (e.g., any suitable combination).

[0116] When an aqueous binder is used as the negative electrode binder, it may further include a cellulose compound capable of imparting viscosity. The cellulose compound may include 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.

[0117] 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).

[0118] A conductive material is included to provide electrode conductivity, and any conductive material can be used as the conductive material unless it causes chemical changes (for example, it should not cause undesirable chemical changes in a rechargeable lithium battery). 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); or mixtures thereof.

[0119] 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 a combination thereof (eg, any appropriate combination), but the present disclosure is not limited thereto.

[0120] Diaphragm

[0121] Depending on the type or kind of 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, a multilayer film of two or more layers thereof (such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator), etc.

[0122] The separator may include a porous substrate and a coating on one or both surfaces (eg, opposite surfaces) of the porous substrate, the coating including an organic material, an inorganic material, and / or a combination thereof (eg, any suitable combination).

[0123] The porous substrate may be a polymer film formed from any one selected from the following: polyolefins (such as polyethylene and / or polypropylene), polyesters (such as polyethylene terephthalate and / or polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyether ketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene oxides, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene (e.g., Teflon), or copolymers or mixtures of two or more thereof.

[0124] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0125] 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), but the present disclosure is not limited thereto.

[0126] 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 stacked.

[0127] Rechargeable lithium battery

[0128] The rechargeable lithium battery may be classified into a cylindrical battery, a prismatic battery, a pouch type or type battery, a coin type or type battery, etc., depending on the shape of the rechargeable lithium battery. Figure 1 to Figure 4 A schematic diagram illustrating a rechargeable lithium battery according to one or more embodiments. Figure 1 A cylindrical battery is shown, Figure 2 A prismatic cell is shown, and Figure 3 and Figure 4 Shows pouch type or kind of battery. Figure 1 to Figure 4 , the rechargeable lithium battery 100 may include an electrode assembly 40 and a case 50 including the electrode assembly 40, the battery assembly 40 including a separator 30 between a positive electrode 10 and a negative electrode 20. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte. Figure 1 As shown, the rechargeable lithium battery 100 may include a sealing member 60 that seals the housing 50. Figure 2 In the embodiment, the rechargeable lithium battery 100 may include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. Figure 3 and Figure 4 As shown, the rechargeable lithium battery 100 may include electrode tabs 70 , which may be, for example, a positive electrode tab 71 and a negative electrode tab 72 serving as an electrical path for guiding (eg, conducting) current formed in the electrode assembly 40 to the outside.

[0129] A rechargeable lithium battery according to some embodiments may be applied to one or more automobiles, mobile phones, and / or one or more appropriate types (kinds) of electric devices, but the present disclosure is not limited thereto.

[0130] Hereinafter, embodiments and comparative examples of the present disclosure are described. However, these examples should not be construed as limiting the scope of the present disclosure in any sense.

[0131] Examples and Comparative Examples

[0132] The electrolyte and rechargeable lithium battery cells were prepared as follows.

[0133] Example 1

[0134] (1) Preparation of electrolyte

[0135] 1.3M LiPF6 was dissolved in a nonaqueous organic solvent in which ethylene carbonate (EC), propylene carbonate (PC) and propyl propionate (PP) were mixed in a volume ratio of 10:15:75, and 0.5 wt% of additives based on the total amount of the electrolyte were added thereto to prepare an electrolyte.

[0136] An additive represented by chemical formula 1-1-1 is used:

[0137] Chemical formula 1-1-1

[0138]

[0139] Perfluoro(2-methyl-3-pentanone) (CAS No.: 756-13-8)

[0140] (2) Manufacturing of rechargeable lithium battery cells

[0141] LiCoO 2 as a positive electrode active material, polyvinylidene fluoride as a binder, and acetylene black as a conductive material were mixed at a weight ratio of 96:3:1, respectively, and then dispersed in N-methylpyrrolidone to prepare a positive electrode active material slurry.

[0142] The positive electrode active material slurry was coated on a 15 μm thick Al foil, dried at 100° C., and pressed to produce a positive electrode.

[0143] Artificial graphite as a negative electrode active material, a styrene-butadiene rubber binder, and carboxymethyl cellulose were dispersed in distilled water at a weight ratio of 98:1:1 to prepare a negative electrode active material slurry.

[0144] The negative electrode active material slurry was coated on a 10 μm thick Cu foil, dried at 100° C., and pressed to produce a negative electrode. The active mass density of the negative electrode was set to 1.7 g / cc.

[0145] An electrode assembly was manufactured by assembling a positive electrode, a negative electrode, and a separator made of polyethylene having a thickness of 10 μm, and an electrolyte was injected, thereby manufacturing a rechargeable lithium battery cell.

[0146] Example 2

[0147] An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that 1 wt % of the additive was added when preparing the electrolyte.

[0148] Example 3

[0149] An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that 1.5 wt % of the additive was added when preparing the electrolyte.

[0150] Example 4

[0151] An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that 2 wt % of the additive was added when preparing the electrolyte.

[0152] Example 5

[0153] An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that 1 wt % of the additive was added when the electrolyte was prepared, and the active mass density was set to 1.75 g / cc when the negative electrode was prepared.

[0154] Example 6

[0155] An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that 1 wt % of the additive was added when the electrolyte was prepared, and the active mass density was set to 1.8 g / cc when the negative electrode was prepared.

[0156] Comparative Example 1

[0157] An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that no additive was added when preparing the electrolyte, and the active mass density was set to 1.65 g / cc when preparing the negative electrode.

[0158] Comparative Example 2

[0159] An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that no additive was added when preparing the electrolyte, and the active mass density was set to 1.67 g / cc when preparing the negative electrode.

[0160] Comparative Example 3

[0161] An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that no additive was added when preparing the electrolyte, and the active mass density was set to 1.7 g / cc when preparing the negative electrode.

[0162] Evaluation Example

[0163] The negative electrodes and the rechargeable lithium battery cells were evaluated in the following manner.

[0164] Evaluation 1: Impregnation properties of electrolyte to negative electrode

[0165] The negative electrode according to Example 1 was manufactured as a sample of width * length = 3 cm * 4 cm. 1 g of the electrolyte according to Example 1 was dropped on the sample and left for 1 minute. Thereafter, the amount of electrolyte impregnated in the sample in 100 wt % of the electrolyte dropped on the sample was evaluated as a value selected from 0 to 5 according to the following standard, and the evaluation results are shown in Table 1.

[0166] 0: When the amount of electrolyte immersed in the sample is 0wt% or more and less than 10wt%

[0167] 1: When the amount of electrolyte immersed in the sample is 10wt% or more and less than 20wt%

[0168] 2: When the amount of electrolyte immersed in the sample is 20wt% or more and less than 40wt%

[0169] 3: When the amount of electrolyte immersed in the sample is 40wt% or more and less than 60wt%

[0170] 4: When the amount of electrolyte immersed in the sample is 60wt% or more and less than 80wt%

[0171] 5: When the amount of electrolyte immersed in the sample is 80wt% or more and less than 100wt%

[0172] Each of the negative electrodes according to Example 2 to Example 6 and Comparative Examples 1 to Comparative Examples 3 was evaluated in substantially the same manner as in Evaluation 1, and the evaluation results are shown in Table 1.

[0173] Table 1

[0174]

[0175] Evaluation 2: Evaluation of room temperature charge and discharge cycle characteristics

[0176] The rechargeable lithium battery cell was charged and discharged 400 times under the conditions of 2.0C charge (CC / CV, 4.47V, 0.025C cutoff) / 1.0C discharge (CC, 3V cutoff) at 25°C.

[0177] The thickness increase rate was calculated according to Equation 1, and the capacity retention rate (cycle life) was calculated according to Equation 2, and the results are shown in Table 2.

[0178] Equation 1

[0179] Thickness increase rate = {(full charge thickness after 400th cycle) - (full charge thickness after 1st cycle)} / (full charge thickness after 1st cycle) * 100

[0180] In Equation 1, “full charge thickness” refers to the thickness of a rechargeable lithium battery cell measured after charging at SOC (state of charge) 100% (when the total charge capacity of the rechargeable lithium battery is set to 100%, charging to 100% charge capacity) after each cycle.

[0181] Equation 2

[0182] Capacity retention rate = (discharge capacity after 400th cycle / discharge capacity after 1st cycle)*100

[0183] Table 2

[0184]

[0185] Summarize

[0186] Referring to Tables 1 and 2, when the electrolyte does not include additives at all (e.g., Comparative Examples 1 to 3), as the active mass density of the negative electrode increases from 1.65 g / cc to 1.7 g / cc, the impregnation properties of the electrolyte to the negative electrode decrease, the thickness of the rechargeable lithium battery cell increases, and the cycle life decreases.

[0187] However, when the active mass density of the negative electrode is set to 1.7 g / cc, the electrolyte including the additive (e.g., Examples 1 to 4) exhibits increased impregnation properties of the electrolyte to the negative electrode, reduced thickness of the rechargeable lithium battery cell, and increased cycle life compared to the electrolyte that does not include the additive at all (Comparative Example 3).

[0188] In addition, when the electrolyte includes the additive, even if the active mass density of the negative electrode is increased from 1.7 g / cc to 1.8 g / cc (for example, Examples 5 and 6), the increase in thickness of the rechargeable lithium battery cell and the decrease in cycle life are suppressed (i.e., the desired rechargeable lithium battery cell thickness and cycle life are achieved).

[0189] When describing embodiments of the present inventive concepts, the use of “may” refers to “one or more embodiments of the present inventive concepts”.

[0190] As used herein, the term "about" and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent deviations of measured or calculated values ​​that will be recognized by one of ordinary skill in the art. "About" as used herein 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, "about" may mean within one or more standard deviations, or within ±30%, 20%, 10%, or 5% of the stated value.

[0191] Furthermore, any numerical range set forth herein is intended to include all sub-ranges of the same numerical precision contained within the range set forth. For example, the range of "1.0-10.0" is intended to include all sub-ranges between the set forth minimum value 1.0 and the set forth maximum value 10.0 (and including the set forth minimum value 1.0 and the set forth maximum value 10.0), that is, having 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, 2.4-7.6. Any maximum numerical limit set forth herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits contained therein. Accordingly, the applicant reserves the right to amend this specification (including the claims) to explicitly set forth any sub-range contained within the range explicitly set forth herein. The battery management system (BMS) device and / or any other related device or component according to the embodiments of the present invention described herein may be implemented using any appropriate hardware, firmware (e.g., a dedicated 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 separate IC chips. Further, the various components of the device can be implemented on a flexible printed circuit film, a tape carrier package (TCP) or a printed circuit board (PCB), or formed on a substrate. Further, the various components of the device can be processes or threads running on one or more processors in one or more computing devices, which execute computer program instructions and interact with other system components to perform the various functions described herein. The computer program instructions are stored in a memory, which can 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-transient computer-readable media, such as, for example, a CD-ROM, a flash drive, etc. Moreover, it should be appreciated 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 particular computing device may be distributed on one or more other computing devices without departing from the scope of the embodiments of the present disclosure.

[0192] Although the present disclosure has been described in conjunction with what are presently considered to be practical embodiments, it should be understood that the present disclosure is not limited to the disclosed embodiments. However, on the contrary, the present disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims and their equivalents.

Claims

1. A rechargeable lithium battery comprising a positive electrode, including a positive electrode active material; a negative electrode, including a negative electrode active material; and Electrolytes, wherein the active mass density of the negative electrode is greater than or equal to 1.7 g / cc, and The electrolyte comprises: Lithium salts; non-aqueous organic solvent; and The additive represented by chemical formula 1: Chemical formula 1 and Wherein, in Chemical Formula 1, R 1 and R 2 Each is independently a fluorine atom or a C1-C10 fluoroalkyl group.

2. The rechargeable lithium battery of claim 1, wherein The active mass density of the negative electrode is 1.7 g / cc to 2.0 g / cc.

3. The rechargeable lithium battery of claim 1, wherein The additive is represented by chemical formula 1-1: Chemical formula 1-1 and in, In Chemical Formula 1-1, R 11 ~R 15 are each independently a hydrogen atom or a fluorine atom, provided that R 11 ~R 15 At least one of is a fluorine atom; and R 21 ~R 27 are each independently a hydrogen atom or a fluorine atom, provided that R 21 ~R 27 At least one of them is a fluorine atom.

4. The rechargeable lithium battery of claim 1, wherein The additive is represented by chemical formula 1-1-1: Chemical formula 1-1-1 5. The rechargeable lithium battery of claim 1, wherein The amount of the additive is 0.5 wt % to 10 wt % based on the total amount of the electrolyte.

6. The rechargeable lithium battery of claim 1, wherein The non-aqueous organic solvent includes carbonate solvents and propionate solvents.

7. The rechargeable lithium battery of claim 6, wherein Based on the total amount of the non-aqueous organic solvent, the amount of the propionate solvent is greater than or equal to 70 volume %.

8. The rechargeable lithium battery of claim 1, wherein The lithium salt is LiPF6.

9. The rechargeable lithium battery of claim 1, wherein The concentration of the lithium salt is 0.1M to 2.0M.

10. The rechargeable lithium battery of claim 1, wherein The positive electrode active material includes lithium nickel composite oxides, lithium cobalt composite oxides, lithium manganese composite oxides, lithium iron phosphate compounds, lithium nickel manganese composite oxides without cobalt, and / or combinations thereof.

11. The rechargeable lithium battery of claim 1, wherein The negative electrode active material includes a carbon-based negative electrode active material, a Si-based negative electrode active material or a combination thereof.

12. The rechargeable lithium battery of claim 1, wherein The rechargeable lithium battery has a charge upper limit voltage greater than or equal to 4.4V.

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