Rechargeable lithium battery

Abstract

The invention relates to a rechargeable lithium battery. A rechargeable lithium battery may include: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; the active mass density of the negative electrode is greater than or equal to about 1.7 g / cc, and the electrolyte comprises: a lithium salt; a non-aqueous organic solvent; and an additive represented by chemical formula 1: chemical formula 1 # imgabs0 #

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0098391 filed on July 27, 2023 in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of the present disclosure described herein relate to rechargeable lithium batteries. Background Art

[0004] Recently, with the rapid 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 carried out.

[0005] A rechargeable lithium battery includes positive and negative electrodes (including active materials capable of intercalating / deintercalating lithium ions), and an electrolyte, and generates electric energy through oxidation and reduction reactions if (eg, when) lithium ions are intercalated / deintercalated from the positive and negative electrodes.

[0006] One area of ​​research of interest is to increase the active mass density of negative electrodes for rechargeable lithium batteries. However, if (e.g., when) the active mass density of the negative electrode is increased, the void volume may decrease, which may increase the amount of electrolyte impregnated into the negative electrode, thereby leading to increased battery thickness and reduced cycle life. Summary of the invention

[0007] Aspects according to one or more embodiments relate to a rechargeable lithium battery that increases the active mass density of a negative electrode while suppressing an increase in battery thickness and a decrease in cycle life.

[0008] 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.

[0009] According to one or more embodiments, a rechargeable lithium battery may include: 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 nonaqueous organic solvent; and an additive represented by Chemical Formula 1:

[0010] Chemical formula 1

[0011] BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 to Figure 4 is a schematic diagram illustrating a rechargeable lithium battery according to one or more embodiments.

[0013] Reference numerals

[0014] 100: Rechargeable lithium battery 10: Positive electrode

[0015] 11: Positive electrode lead tab 12: Positive terminal

[0016] 20: Negative electrode 21: Negative electrode lead lug

[0017] 22: Negative terminal 30: Separator

[0018] 40: electrode assembly 50: shell

[0019] 60: Sealing member 70: Electrode terminal piece

[0020] 71: Positive electrode terminal tab 72: Negative electrode terminal tab DETAILED DESCRIPTION

[0021] 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 present disclosure is defined by the scope of the claims.

[0022] As used herein, if (for example, when) specific definitions are otherwise provided, 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.

[0023] As used herein, if (for example, when) no specific definition is otherwise provided, the singular may also include the plural. In one or more embodiments, "A or B" may mean "including A, including B, or including A and B", unless otherwise specified.

[0024] As used herein, expressions such as "at least one of," "one of," and "of (e.g., selected from)," when preceding / following a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, "at least one selected from a, b, and c" may mean only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0025] The terms used in this article are only intended to describe specific embodiments and are not intended to limit the present disclosure. As used in this article, the singular forms "a", "an" and "the" (including "at least one") are intended to include plural forms, unless the content (e.g., amount) is clearly indicated in other ways. "At least one" should not be interpreted as being limited to the singular. As used in this article, the term "and / or" includes any and all combinations of one or more related enumerated items. The terms "includes", "including", "comprises" and / or "comprising", when used in the detailed description, specify the presence of narrated features, regions, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components and / or groups thereof.

[0026] Spatially relative terms such as "below," "below," "below," "above," and "on" may be used herein to easily describe the relationship of one element or feature to another element or feature. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation illustrated in the drawings. For example, when the device in the drawings is turned over, elements described as being "below" or "below" other elements or features will be "above" or "on" the other elements or features. In some embodiments, the example term "below" may encompass both the orientations above and below (e.g., encompassing both the orientations above and below). The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative terms used herein may be interpreted accordingly.

[0027] As used herein, the term "metal" includes all metals and metalloids, such as silicon and germanium, in either elemental or ionic form.

[0028] As used herein, the term "alloy" refers to a mixture of two or more metals.

[0029] As used herein, the term "electrode active material" refers to an electrode material that can undergo lithiation and delithiation.

[0030] As used herein, the term "positive electrode active material" refers to a positive electrode material that can undergo lithiation and delithiation.

[0031] The term "negative electrode active material" as used herein refers to a negative electrode material that can undergo lithiation and delithiation.

[0032] As used herein, "lithiate" and "lithiating" refer to the process of adding lithium to an electrode active material.

[0033] As used herein, the terms "delithiate" and "delithiating" refer to the process of removing lithium from an electrode active material.

[0034] As used herein, the terms "charge" and "charging" refer to the process of providing electrochemical energy to a battery.

[0035] As used herein, the terms "discharge" and "discharging" refer to the process of removing electrochemical energy from a battery.

[0036] As used herein, the terms "positive electrode" and "cathode" refer to the electrode that undergoes electrochemical reduction and lithiation during the discharge process.

[0037] As used herein, the terms "negative electrode" and "anode" refer to the electrode that undergoes electrochemical oxidation and delithiation during the discharge process.

[0038] As used herein, the term "substantially" and similar terms 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 would be recognized by one of ordinary skill in the art. Also, the term "about" and similar terms, when used herein in conjunction with a numerical value or range of values, include both the recited value and values ​​within an acceptable range of deviation for 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 recited value.

[0039] Furthermore, any numerical range set forth in this article is intended to include all sub-ranges of the same numerical precision contained in the set forth range. 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 in this article 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 modify this specification (including claims) to explicitly set forth any sub-range contained in the range explicitly set forth herein.

[0040] As used herein, "combinations thereof" may refer to mixtures, stacks, composites, copolymers, alloys, blends, and reaction products of the components.

[0041] As used herein, “active mass density of the negative electrode” is 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.

[0042] 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.

[0043] As used herein, if (eg, when) no definition is otherwise provided, "*" refers to moieties that are attached to the same or different atoms or chemical formulas.

[0044] In the present specification, the "number average molecular weight" is a value measured by gel permeation chromatography (GPC, PL GPC220, Agilent Technologies) and calibrated with a cubic function using polystyrene.

[0045] Rechargeable lithium battery

[0046] 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 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 nonaqueous organic solvent; and an additive represented by Chemical Formula 1:

[0047] Chemical formula 1

[0048]

[0049] The additive functions 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).

[0050] The additives include *-[O-CH(R 1 )-CH2] y -* block, and *-[O-CH2-CH2] on both sides (e.g., opposite sides) of the molecule x -*block and *-[O-CH2-CH2] z -* block. In this article, *-[O-CH(R 1 )-CH2] y -* is a hydrophobic block, and *-[O-CH2-CH2] x -*block and *-[O-CH2-CH2] z -* blocks are each a hydrophilic block.

[0051] Accordingly, if (for example, when) an electrolyte including an additive is used, wettability of the electrolyte to the positive electrode and the negative electrode is improved, and lithium cations (Li ions) are uniformly (substantially uniformly) formed at the interface between the positive electrode and the electrolyte. + ), and form a stable SEI film at the interface between the negative electrode and the electrolyte, thereby inhibiting or reducing the precipitation of lithium dendrites.

[0052] Therefore, by using an electrolyte including the above additives, while increasing the active mass density of the negative electrode to about 1.7 g / cc or more, an increase in battery thickness and a decrease in cycle life can be suppressed or reduced.

[0053] Hereinafter, a rechargeable lithium battery according to one or more embodiments will be described in more detail.

[0054] Active mass density of negative electrode

[0055] Typically, suitable 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 one or more embodiments use a negative electrode having an active mass density (e.g., mixed density) greater than or equal to about 1.7 g / cc.

[0056] 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.

[0057] Charging upper limit voltage

[0058] In the rechargeable lithium battery according to one or more embodiments, by using an electrolyte including the above additives, even if the active mass density of the negative electrode increases, an increase in battery thickness and a decrease in cycle life may be suppressed or reduced.

[0059] For example, a rechargeable lithium battery may have a charge upper limit voltage greater than or equal to about 4.5V.

[0060] additive

[0061] In Chemical Formula 1, R 1 It is a hydrogen atom or a C1-C10 alkyl group.

[0062] For example, R 1 It may be methyl.

[0063] In Chemical Formula 1, x, y and z are independently integers selected from 1-20.

[0064] Herein, the molar ratio of x:y may be about 10:1 to about 1:10, about 5:1 to about 1:5, or about 3:1 to about 1:3. In one or more embodiments, the molar ratio of y:z may be about 10:1 to about 1:10, about 5:1 to about 1:5, or about 3:1 to about 1:3.

[0065] The additive may have a number average molecular weight in a range of about 500 g / mol to about 10,000 g / mol, about 700 g / mol to about 8,000 g / mol, or about 1,000 g / mol to about 2,000 g / mol.

[0066] If (for example, when) the number average molecular weight of the additive exceeds the above range, the wettability of the electrolyte to the positive electrode and the negative electrode may be reduced because the viscosity of the electrolyte including the additive is excessively increased. In contrast, if (for example, when) the number average molecular weight of the additive is less than the range, the effect of the additive as a surfactant may not be obvious.

[0067] The additive can be represented by chemical formula 1-1:

[0068] Chemical formula 1-1

[0069]

[0070] The additive represented by Chemical Formula 1-1 may be poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), ie, PEG-b-PPG-b-PEG.

[0071] In Chemical Formula 1-1, x, y and z are equally defined as above.

[0072] Content of additives

[0073] The additive may be included in an amount of about 0.1 wt % to about 5 wt %, about 0.2 wt % to about 2 wt %, or about 0.5 wt % to about 1 wt % based on 100 wt % of the total amount of the electrolyte.

[0074] If the additive is included in an amount exceeding the above range, the viscosity of the electrolyte including the additive may be excessively increased, and the wettability of the electrolyte to the positive electrode and the negative electrode may actually be reduced. In contrast, if the additive is included in an amount below the above range, the effect of the additive as a surfactant may be minimized.

[0075] Non-aqueous organic solvents

[0076] The nonaqueous organic solvent serves as a medium for transmitting ions participating in the electrochemical reaction of the battery.

[0077] The non-aqueous organic solvent may include a carbonate-based solvent, an ester-based solvent (eg, a propionate-based solvent), an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, an aprotic solvent, and / or a combination thereof (eg, an appropriate combination thereof).

[0078] 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, propyl propionate (PP), decanoic acid lactone, mevalonolactone, valerolactone, caprolactone, etc.

[0079] 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 (wherein 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-dioxolanes or 1,4-dioxolanes), sulfolane, etc.

[0080] The nonaqueous organic solvent may be used alone or in combination of two or more thereof.

[0081] In the case of using a combination of two or more of the nonaqueous organic solvents, the nonaqueous organic solvent may include a carbonate-based solvent and a propionate-based solvent.

[0082] The propionate-based solvent may be included in an amount of greater than or equal to about 70 volume % based on 100 volume % of the total amount of the non-aqueous organic solvent. In this case, high voltage and / or high temperature characteristics of the rechargeable lithium battery can be improved.

[0083] For example, the nonaqueous organic solvent may be a mixed solvent of ethylene carbonate (EC), propylene carbonate (PC), and propyl propionate (PP).

[0084] Lithium salts

[0085] The lithium salt dissolved in the nonaqueous 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.

[0086] LiPF6 can be used as a lithium salt.

[0087] The concentration of the lithium salt may be about 0.1M to about 2.0M.

[0088] Positive electrode active material

[0089] The positive electrode active material may be a compound capable of intercalating / deintercalating lithium (lithiated intercalation compound). For example, a composite oxide of lithium and one or more types (species) of metal selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0090] The composite oxide may be a lithium transition metal composite oxide, and specific examples may include lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese oxides and / or combinations thereof (e.g., appropriate combinations thereof).

[0091] As an example, a compound represented by (eg, selected from) any one of the following chemical formulae 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); Lia Mn 1-b G b O2(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); and / or Li a FePO4(0.90≤a≤1.8).

[0092] In the above chemical formula, A is Ni, Co, Mn and / or a combination thereof (e.g., a 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., a suitable combination thereof); D is O, F, S, P and / or a combination thereof (e.g., a suitable combination thereof); G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and / or a combination thereof (e.g., a suitable combination thereof); and L 1 is Mn, Al and / or a combination thereof (eg, a suitable combination thereof).

[0093] As an example, based on about 100 mol% of 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%. In one or more embodiments, based on about 100 mol% of metal excluding lithium in the lithium transition metal composite oxide, the positive electrode active material may be a relatively high nickel-based positive electrode active material having a nickel content of less than or equal to about 99 mol%. Relatively high nickel-based positive electrode active materials can achieve relatively high capacity and can be applied to relatively high capacity, relatively high density rechargeable lithium batteries.

[0094] The positive electrode active material may be, for example, a lithium nickel-based oxide represented by Chemical Formula 11, a lithium cobalt-based oxide represented by Chemical Formula 12, a lithium iron phosphate-based compound represented by Chemical Formula 13, a cobalt-free lithium nickel manganese-based oxide represented by Chemical Formula 14, and / or combinations thereof (e.g., appropriate combinations thereof).

[0095] Chemical formula 11

[0096] Li a1 Ni x1 M 1y1 M 2 z1 O 2-b1 X b1

[0097] 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 them may independently be one or more elements selected from 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 F, P and S.

[0098] In Chemical Formula 11, 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.4, or 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2.

[0099] Chemical formula 12

[0100] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0101] 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 is 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 is one or more elements selected from F, P and S.

[0102] Chemical formula 13

[0103] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0104] 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 4is 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 is one or more elements selected from F, P, and S.

[0105] Chemical formula 14

[0106] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0107] In Chemical formula 14, 0.9 ≤ a2 ≤ 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 is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from F, P, and S.

[0108] In particular, the electrolyte of the above embodiment can significantly improve the high-voltage and / or high-temperature characteristics of a battery using a lithium cobalt oxide represented by Chemical formula 12.

[0109] Positive electrode

[0110] 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.

[0111] For example, the positive electrode may further include an additive that can act as a sacrificial positive electrode.

[0112] Based on about 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 be about 0.5 wt% to about 5 wt% respectively.

[0113] The binder is used to attach the positive electrode active material particles to each other well, and also to attach the positive electrode active material to the positive electrode current collector well. 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.

[0114] Conductive materials can be used to impart electrical conductivity (e.g., electrical conductivity) to the 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 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); or mixtures thereof.

[0115] Al foil may be used as a positive electrode current collector, but the present disclosure is not limited thereto.

[0116] Negative electrode active material

[0117] 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, or a transition metal oxide.

[0118] 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., a suitable combination thereof). The crystalline carbon may be graphite (such as amorphous, flaky, sheet-like, spherical or fibrous natural graphite or artificial graphite). The amorphous carbon may be soft carbon, hard carbon, a mesophase pitch carbonization product, calcined coke, etc.

[0119] The lithium metal alloy may include lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0120] 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, silicon-carbon composites, SiO x(0 < x ≤ 2), 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., suitable combinations 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., suitable combinations thereof).

[0121] 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 and an amorphous carbon coating (shells) on the surface of the secondary particles. Amorphous carbon may also be 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.

[0122] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core.

[0123] 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.

[0124] Negative electrode

[0125] 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.

[0126] For example, the negative electrode active material layer may include about 90 wt% to about 99 wt% of a negative electrode active material, about 0.5 wt% to about 5 wt% of a binder, and about 0 wt% to about 5 wt% of a conductive material based on 100 wt% of the negative electrode active material layer.

[0127] The binder may be used to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the negative electrode current collector. The binder may include a non-aqueous binder, an aqueous binder, a dry binder, and / or combinations thereof (e.g., suitable combinations thereof).

[0128] 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 (e.g., suitable combinations thereof).

[0129] 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., appropriate combinations thereof).

[0130] 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.

[0131] The dry binder may be a polymer material capable of fiberization, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, a polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and / or a combination thereof (eg, a suitable combination thereof).

[0132] 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 a carbon-based material (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.); a metal-based material containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; a conductive polymer (such as a polyphenylene derivative); or a mixture thereof.

[0133] 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, appropriate combinations thereof), but the present disclosure is not limited thereto.

[0134] Diaphragm

[0135] 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, 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.

[0136] 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, a suitable combination thereof).

[0137] 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 / and mixtures of two or more thereof.

[0138] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0139] 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., appropriate combinations thereof), but the present disclosure is not limited thereto.

[0140] 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.

[0141] Rechargeable lithium battery

[0142] The rechargeable lithium battery may be classified into a cylindrical battery, a prismatic battery, a pouch type or type battery, or 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 in which the electrode assembly 40 is accommodated, 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 4As 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 current formed in the electrode assembly 40 to the outside.

[0143] A rechargeable lithium battery according to some embodiments may be applied to automobiles, mobile phones, and / or one or more appropriate types (kinds) of electronic devices, but the present disclosure is not limited thereto.

[0144] Hereinafter, examples and comparative examples of the present disclosure are described. However, these examples are by no means interpreted as limiting the scope of the present disclosure.

[0145] Examples and Comparative Examples

[0146] The electrolyte and rechargeable lithium battery cells were prepared as follows.

[0147] Example 1

[0148] (1) Preparation of electrolyte

[0149] About 1.3 M 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 about 10:15:75, and about 0.2 wt% of an additive based on the total amount of the electrolyte was added thereto to prepare an electrolyte.

[0150] An additive represented by chemical formula 1-1 is used:

[0151] Chemical formula 1-1

[0152]

[0153] Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-b-PPG-bP, CAS No.: 9003-11-6, x=1-20, y=1-20, z=1-20, number average molecular weight: 1,100 g / mol)

[0154] (2) Manufacturing of rechargeable lithium battery cells

[0155] 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 about 96:3:1, respectively, and then dispersed in N-methylpyrrolidone to prepare a positive electrode active material slurry.

[0156] The positive electrode active material slurry was coated on an Al foil having a thickness of about 15 μm, dried at about 100° C., and pressed to produce a positive electrode.

[0157] 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 about 98:1:1 to prepare a negative electrode active material slurry.

[0158] The negative electrode active material slurry was coated on a Cu foil of about 10 micrometers thick (μm thick), dried at about 100° C., and pressed to produce a negative electrode. At this time, the active mass density of the negative electrode was set to about 1.7 g / cc.

[0159] An electrode assembly was manufactured by assembling a positive electrode, a negative electrode, and a separator made of polyethylene having a thickness of about 10 μm, and an electrolyte was injected to manufacture a rechargeable lithium battery cell.

[0160] Example 2

[0161] An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1, except that the additive was added in an amount of about 0.5 wt % to prepare the electrolyte.

[0162] Example 3

[0163] An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1, except that the additive was added in an amount of about 1 wt % to prepare the electrolyte.

[0164] Example 4

[0165] An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1, except that the electrolyte was prepared by adding about 1 wt % of the additive, and the negative electrode was manufactured to have an active mass density of about 1.75 g / cc.

[0166] Example 5

[0167] An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1, except that the electrolyte was prepared by adding about 1 wt % of the additive, and the negative electrode was manufactured to have an active mass density of about 1.8 g / cc.

[0168] Comparative Example 1

[0169] An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1, except that the electrolyte was prepared by adding no additives at all, and the negative electrode was manufactured to have an active mass density of about 1.65 g / cc.

[0170] Comparative Example 2

[0171] An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1, except that the electrolyte was prepared by adding no additives at all, and the negative electrode was manufactured to have an active mass density of about 1.67 g / cc.

[0172] Comparative Example 3

[0173] An electrolyte and a rechargeable lithium battery cell were manufactured in substantially the same manner as in Example 1, except that the electrolyte was prepared by adding no additives at all, and the negative electrode was manufactured to have an active mass density of about 1.7 g / cc.

[0174] Evaluation Example

[0175] The negative electrodes and the rechargeable lithium battery cells were evaluated in the following manner.

[0176] Evaluation 1: Impregnation characteristics of the negative electrode with the electrolyte

[0177] The negative electrode according to Example 1 was manufactured as a sample of width × (e.g., *) length = about 3 cm × about 5 cm. About 1 g of the electrolyte according to Example 1 was dropped on the sample and left for about 20 minutes. Thereafter, the amount of the electrolyte immersed in the sample in about 100 wt % of the electrolyte dropped on the sample was evaluated as a value of 0 to 5 according to the following standard, and the evaluation results are shown in Table 1:

[0178] 0: When the amount of the electrolyte immersed in the sample is 0 wt% or more and less than about 10 wt%

[0179] 1: When the amount of the electrolyte immersed in the sample is about 10 wt % or more and less than about 20 wt %

[0180] 2: When the amount of the electrolyte immersed in the sample is about 20 wt % or more and less than about 40 wt %

[0181] 3: When the amount of the electrolyte immersed in the sample is about 40 wt % or more and less than about 60 wt %

[0182] 4: When the amount of the electrolyte immersed in the sample is about 60 wt % or more and less than about 80 wt %

[0183] 5: When the amount of the electrolyte immersed in the sample is about 80 wt % or more and less than about 100 wt %

[0184] Each of the negative electrodes according to Example 2 to Example 5 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.

[0185] Table 1

[0186]

[0187] Evaluation 2: Evaluation of room temperature charge and discharge cycle characteristics

[0188] The rechargeable lithium battery cell was charged and discharged about 400 times under the conditions of about 25° C., about 2.0 C charge (CC / CV, 4.53 V, 0.025 C cutoff) / about 1.0 C discharge (CC, 3 V cutoff).

[0189] The thickness increase rate was calculated according to Equation 1, the capacity retention rate (cycle life) was calculated according to Equation 2, and the results are shown in Table 2.

[0190] Equation 1

[0191] Thickness increase rate = {(full charge thickness after 400th cycle) – (full charge thickness after 1st cycle)} / (full charge thickness after 1st cycle) × 100

[0192] In Equation 1, “full charge thickness” refers to the thickness of the rechargeable lithium battery cell measured after charging at about SOC 100% (charged to about 100% charge capacity if (e.g., when) the total charge capacity of the rechargeable lithium battery cell is set to about 100%) after each cycle.

[0193] Equation 2

[0194] Capacity retention rate = (discharge capacity after 400th cycle / discharge capacity after 1st cycle) × 100

[0195] Table 2

[0196]

[0197] Summarize

[0198] Referring to Tables 1 and 2, for the electrolytes prepared without adding any additives (Comparative Examples 1 to 3), when the active mass density of the negative electrode increased from about 1.65 g / cc to about 1.7 g / cc, the impregnation characteristics of the electrolyte to the negative electrode were reduced and the thickness of the rechargeable lithium battery cell was increased, resulting in a deterioration in the cycle life.

[0199] However, compared to the electrolyte that does not include any additives at all (Comparative Example 3), when the negative electrode has the same active mass density of about 1.7 g / cc, the electrolyte including the additives (Examples 1 to 3) exhibits increased impregnation characteristics of the electrolyte to the negative electrode, resulting in an increase in cycle life.

[0200] Furthermore, the electrolyte includes the additive to suppress or reduce the increase in thickness and the decrease in cycle life of the rechargeable lithium battery cell even if the active mass density of the negative electrode is increased from about 1.7 g / cc to about 1.8 g / cc (Examples 4 and 5).

[0201] In the present disclosure, "does not include one or any 'component'", "excludes one or any 'component'", "no 'component'" and the like mean that the "component" is not added, selected or used as a component in the composition or compound, but due to other impurities and / or external factors, the "component" may still be included in an amount less than the appropriate amount.

[0202] 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, one or more appropriate components of the device may be formed on an integrated circuit (IC) chip or on separate IC chips. Further, one or more appropriate 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. Further, one or more appropriate components of the device may be a process or thread 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 one or more appropriate 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-transitory computer-readable media, such as, for example, a CD-ROM, a flash drive, etc. Moreover, those skilled in the art will recognize that, without departing from the scope of the present disclosure, the functions of one or more appropriate 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.

[0203] While the disclosure has been described in conjunction with what are presently considered to be practical embodiments, it should be understood that the disclosure should not be limited to the disclosed embodiments, but, on the contrary, the disclosure is intended to cover one or more suitable 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 Electrolyte, 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 is a hydrogen atom or a C1-C10 alkyl group; and x, y and z are each independently an integer selected from 1-20.

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 R 1 It is methyl.

4. The rechargeable lithium battery of claim 1, wherein The number average molecular weight of the additive is 500 g / mol to 10,000 g / mol.

5. The rechargeable lithium battery of claim 1, wherein The additive is included in an amount of 0.1 wt% to 5 wt% based on 100 wt% of 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 The propionate-based solvent is included in an amount of greater than or equal to 70 volume % based on 100 volume % of the total amount of the non-aqueous organic solvent.

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 oxide, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate compound, lithium nickel manganese oxide without cobalt and / or a combination 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 4.5V.

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