Rechargeable lithium battery

Abstract

The invention relates to a rechargeable lithium battery. A rechargeable lithium battery includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. The positive electrode includes a first positive electrode active material including a lithium nickel-based composite oxide and in the form of a secondary particle in which a plurality of primary particles are aggregated. The positive electrode includes a second positive electrode active material that includes a lithium nickel-based composite oxide and is in the form of a single particle. The non-aqueous electrolyte comprises an organic solvent, a lithium salt and an additive, and the additive comprises a bicyclic sulfate compound.

Description

Technical Field

[0001] According to one or more embodiments, the present disclosure relates to a rechargeable lithium battery. Background Art

[0002] A rechargeable lithium battery having a relatively high energy density and a relatively high portability can be used as a driving power source for a portable information device (such as a mobile phone, a laptop computer, a smart phone, etc.) and / or an electric vehicle. Recently, research has been actively conducted to use a rechargeable lithium battery having a relatively high energy density as a driving power source, for example, for a hybrid electric vehicle and / or an electric vehicle and / or an energy storage power source, for example, for a residential energy storage (e.g., a power wall).

[0003] In order to meet these purposes, a nickel-based positive electrode active material capable of ensuring high capacity is applied to the positive electrode of a rechargeable lithium battery. However, if (for example, when) a nickel-based positive electrode active material is used in a high-voltage battery, a degradation reaction (such as generation of gas, etc.) may occur, for example, due to by-products on the surface of the positive electrode active material. As a result, due to the substantially continuous generation of side reactants, the resistance may increase significantly during the discharge / charge cycle, and the battery performance may deteriorate, for example, due to the decomposition of the electrolyte at high temperatures.

[0004] Recently, research is being conducted to prepare nickel-based positive electrode active materials by mixing secondary particles with single particles to compensate for the degradation that occurs when the secondary particles are used alone. However, if (for example, when) an electrode is formed by mixing particles having different shapes, gas may be generated due to differences in the extent of reaction on the surface of each type or type of particles. For example, residual lithium that causes side reactions may exist unevenly (substantially unevenly), and due to different reaction rates (for example, of lithium) on the particle interface and inside the particle, the particles may degrade unevenly (substantially unevenly). Summary of the invention

[0005] One or more aspects relate to a positive electrode design using a nickel-based positive electrode active material prepared by mixing particles having different shapes and a non-aqueous electrolyte capable of forming (or providing) a stable protective layer having high conductivity on the positive electrode surface.

[0006] One or more aspects relate to a rechargeable lithium battery capable of suppressing or reducing gas generation, and also capable of suppressing or reducing substantially non-uniform reaction and resistance increase in an electrode due to substantially continuous generation of a side reactant.

[0007] 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.

[0008] According to one or more embodiments, a rechargeable lithium battery includes a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte, wherein the positive electrode includes a first positive electrode active material and a second positive electrode active material. The first positive electrode active material may be in the form of secondary particles and include a lithium nickel composite oxide, and the secondary particles include a plurality of primary particles, and the plurality of primary particles are aggregated (e.g., aggregated into secondary particles or aggregated into each of the secondary particles). The second positive electrode active material may be in the form of a single particle (e.g., each is a whole particle) and includes a lithium nickel composite oxide. The non-aqueous electrolyte includes an organic solvent, a lithium salt and an additive, and the additive includes a bicyclic sulfate compound represented by Chemical Formula 1.

[0009] A rechargeable lithium battery according to some embodiments can achieve a relatively high capacity and a relatively high energy density, and effectively suppress or reduce resistance increase caused by, for example, a solid protective layer having high conductivity on the surface of the positive electrode. The rechargeable lithium battery can also suppress or reduce the increase of side reactions (e.g., caused by repeated charging and discharging) to improve resistance increase during cycling. The rechargeable lithium battery can also improve (e.g., absorb) the amount of gas generated due to substantially continuous cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 to Figure 4 Each is a view schematically showing a rechargeable lithium battery according to some embodiments.

[0011] Description of Reference Numerals

[0012] 100: Rechargeable lithium battery 10: Positive electrode

[0013] 11: Positive electrode lead lug 12: Positive electrode terminal

[0014] 20: Negative electrode 21: Negative electrode lead lug

[0015] 22: Negative electrode terminal 30: Separator

[0016] 40: electrode assembly 50: shell

[0017] 60: Sealing member 70: Electrode terminal piece

[0018] 71: Positive electrode terminal tab 72: Negative electrode terminal tab DETAILED DESCRIPTION

[0019] Hereinafter, specific embodiments will be described in more detail so that those of ordinary skill in the art can easily implement them. Examples thereof are illustrated in the accompanying drawings, wherein the same reference numerals refer to the same elements throughout, and a repeated description thereof may not be provided. Accordingly, embodiments are described only by reference to the accompanying drawings to explain aspects of the present description. However, the present disclosure may be implemented in many different forms and is not to be construed as being limited to the example embodiments set forth herein, but rather, the present disclosure is limited by the scope of the claims.

[0020] The terms used herein are only used to describe the embodiments and are not intended to limit the present disclosure. Unless the context clearly indicates otherwise, the singular expressions "a", "an" and "the" include plural expressions, including "at least one".

[0021] As used herein, "combinations thereof" refers to mixtures, laminates, composites, copolymers, alloys, blends, reaction products, and the like, of the components.

[0022] In this document, it should be understood that terms such as “comprises,” “comprise,” “comprising,” “includes,” “including,” “include,” “having,” “has,” and / or “have” are intended to indicate the presence of the implemented aspects, features, quantities, operations, elements, and / or any appropriate combination thereof, but do not exclude the possibility of the presence or addition of one or more other aspects, features, quantities, operations, elements, and / or any appropriate combination thereof.

[0023] In the drawings, the thickness of layers, films, plates, regions, etc. are exaggerated for clarity, wherein the same reference numerals denote the same elements, and a repeated description thereof may not be provided throughout the specification. 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 may be directly on the other element (such as a layer, film, region, or substrate), or there may also be intervening elements. On the contrary, if (for example, when) an element is referred to as being "directly on" another element, there are no intervening elements.

[0024] In one or more embodiments, the term “layer” herein includes not only a shape formed on the entire surface when viewed from a plan view but also a shape formed on a partial surface.

[0025] It will be understood that although the terms "first", "second", "third", etc. may be used herein to describe one or more appropriate elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings set forth herein, a first element, component, region, layer or part described herein may be referred to as a second element, component, region, layer or part.

[0026] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of," "one of," and "selected from..." if (e.g., when) preceding or following a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, the expressions "at least one of a-c" and "at least one of a, b, and c" may indicate 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.

[0027] Spatially relative terms such as "below," "below," "below," "above," and "on" may be used herein to easily describe the relationship between one element or feature and another element or feature. It will be understood that in addition to the orientations illustrated in the drawings, the spatially relative terms are intended to encompass different orientations of the device in use or operation. For example, if (e.g., when) the device in the drawings is flipped, the elements described as "below" or "below" other elements or features will be oriented "above" the other elements or features. Therefore, the example term "below" can encompass both orientations of "above" and "below" (e.g., can encompass both orientations of "above" and "below" at the same time). The device can be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative terms used herein can be interpreted accordingly.

[0028] The terms used in this article are only used to describe specific embodiments and are not intended to limit the present disclosure. Unless otherwise defined, all terms used in this article (including chemical terms, technical terms and scientific terms) have the same meaning as the meanings commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having meanings consistent with their meanings in the context of the prior art and the present disclosure, and will not be interpreted in an idealized or overly formal sense.

[0029] Example embodiments are described herein with reference to the drawings, which are schematic diagrams of ideal embodiments. As such, variations in the shapes illustrated are expected due to, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be interpreted as being limited to the specific shapes of the zones illustrated herein, but rather include shape deviations, for example, caused by manufacturing. For example, a zone illustrated or described as flat may typically have rough and / or nonlinear features. Moreover, the illustrated sharp corners may be rounded. Therefore, the zones illustrated in the drawings are schematic in nature, and their shapes are not intended to illustrate the precise shape of the zones, and are not intended to limit the scope of the claims.

[0030] The term "may" will be understood to refer to "one or more embodiments of the present disclosure," some of which include the described elements, while some do not include the elements and / or include alternative elements. Similarly, alternative language such as "or" refers to "one or more embodiments of the present disclosure" that each include the corresponding enumerated items.

[0031] In this context, "consisting essentially of" means that any additional components will not have a significant effect on the chemical, physical, optical or electrical properties of the target moiety.

[0032] Further, in this specification, the phrase "on a plane" or "plan view" means observing a target portion from the top, and the phrase "on a cross section" means observing a cross section formed by vertically cutting the target portion from the side.

[0033] definition

[0034] The term "particle size" as used herein refers to the average diameter of the particles if (for example, when) the particles are spherical, and refers to the average major axis length of the particles if (for example, when) the particles are non-spherical. For example, the average particle size can be measured by methods well known to those skilled in the art, for example, by a particle size analyzer, or by a transmission electron microscope image or a scanning electron microscope image. The average particle size value can be obtained by measuring using a dynamic light scattering method, performing data analysis, counting the number of particles in each particle size range, and calculating therefrom. Unless otherwise specified, the average particle size (D 50 ) may refer to the diameter of particles with a cumulative volume of 50% by volume in a particle size distribution. If (for example, when) the measurement is performed by laser diffraction, more specifically, the particles to be measured are dispersed in a dispersion medium, and then ultrasonic waves of about 28 kHz are introduced into a laser diffraction particle size measuring device of the prior art (for example, MT 3000 available from Microtrac, Ltd.), and after irradiation at an output power of 60 W, the average particle diameter (D ) based on the 50% particle size distribution in the measuring device can be calculated. 50If (for example, when) no definition is otherwise provided, the average particle size (D 50 ) refers to the diameter of particles accounting for 50% by volume of the cumulative volume in a particle size distribution obtained by randomly measuring the sizes (diameters or major axis lengths) of about 20 particles in a scanning electron microscope image.

[0035] In the present disclosure, "not including one or any 'component'", "excluding 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 / structure, but due to other impurities and / or external factors, the "component" may still be included in an appropriate amount less than that.

[0036] In this document, "or" is not interpreted as an exclusive meaning. For example, "A or B" is interpreted to include A, B, A+B, etc.

[0037] The term "metal" is interpreted as a concept including common metals, transition metals and metalloids (semimetals).

[0038] As used herein, "substituted" means that at least one hydrogen of a compound is replaced by (e.g., selected from) a halogen atom (F, Cl, Br or I), a hydroxyl group, a C1-C20 alkoxy group, a nitro group, a cyano group, an amine group, an imino group, an azido group, a carbamimido group, a hydrazine group, a hydrazone group, a carbonyl group, a carbamoyl group, a thiol group, an ester group, an ether group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphate group or a salt thereof, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, a C6-C20 aryl group, a C3-C20 cycloalkyl group, a C3-C20 cycloalkenyl group, a C3-C20 cycloalkynyl group, a C2-C20 heterocycloalkyl group, a C2-C20 heterocycloalkenyl group, a C2-C20 heterocycloalkynyl group, a C3-C20 heteroaryl group and / or any suitable combination thereof.

[0039] Herein, for example, C1-C20 means having 1 to 20 carbon atoms.

[0040] Rechargeable lithium battery

[0041] According to the shape, the rechargeable lithium batteries can be classified into cylindrical, prismatic, pouch, coin, etc. Figure 1 to Figure 4 Each is a view schematically showing a rechargeable lithium battery according to some embodiments. Figure 1 A cylindrical battery is shown, Figure 2 A prismatic cell is shown, and Figure 3 and Figure 4 Shows a pouch type (or kind) battery. Figure 1 to Figure 4, the rechargeable lithium battery 100 includes: an electrode assembly 40 having a separator 30 interposed between a positive electrode 10 and a negative electrode 20; and a case 50 in which the electrode assembly 40 is accommodated. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte (not shown). Figure 1 As shown, the rechargeable lithium battery 100 may include a sealing member 60 that seals the housing 50. In one or more embodiments, 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 As shown, the rechargeable lithium battery 100 includes a positive electrode tab 71 and a negative electrode tab 72, which serve as an electrical path for guiding the current formed in the electrode assembly 40 to the outside. Figure 4 As shown, the rechargeable lithium battery 100 includes an electrode tab 70 .

[0042] In some embodiments, the rechargeable lithium battery includes a positive electrode, a negative electrode, a separator and a non-aqueous electrolyte. The positive electrode includes a first positive electrode active material and a second positive electrode active material. The first positive electrode active material may be in the form of secondary particles and include a lithium nickel composite oxide, and the secondary particles may include a plurality of primary particles, and the plurality of primary particles may be aggregated (e.g., aggregated into a secondary particle or each of the secondary particles). The second positive electrode active material may be in the form of a single particle (e.g., each is a whole particle) and include a lithium nickel composite oxide. The non-aqueous electrolyte may include an organic solvent, a lithium salt and an additive, and the additive may include a bicyclic sulfate compound represented by Chemical Formula 1.

[0043] Positive electrode

[0044] The positive electrode may include a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector, and the positive electrode active material layer may include a positive electrode active material and may (e.g., optionally) further include a binder, a conductive material and / or (e.g., any appropriate) combination thereof. The positive electrode active material according to some embodiments includes a first positive electrode active material and a second positive electrode active material, each having a different shape. In some embodiments, the first positive electrode active material includes a lithium nickel composite oxide and is in the form of secondary particles in which a plurality of primary particles are aggregated (e.g., a plurality of primary particles may be aggregated to form (or provide) secondary particles). In some embodiments, the second positive electrode active material includes a lithium nickel composite oxide and is in the form of a single particle (or provides a single particle).

[0045] Nickel-based positive electrode active materials including lithium nickel-based composite oxides can achieve or realize relatively high capacity and relatively high charge / discharge efficiency. However, as (e.g., undesirable) side reactions accelerate during the discharge / charge cycle (e.g., on the surface of the particles of the positive electrode active material), the positive electrode active material may undesirably produce gas products and increase resistance, thereby deteriorating (e.g., the cycle life characteristics of the battery). Nickel-based positive electrode active materials may (e.g., usually) be in the form of secondary particles having a size of several microns (μm) to tens of microns (or provide secondary particles having a size of several microns (μm) to tens of microns), which may be severely broken due to repeated charging and discharging. Cracks may expose the unreacted (e.g., newly exposed) surface of the primary particles, thereby increasing the amount of undesirable side reactions and the resistance of the battery. In order to avoid (e.g., compensate for) degradation characteristics (e.g., degradation characteristics in the case of using secondary particles alone as nickel-based positive electrode active materials), the present disclosure includes a method for manufacturing a positive electrode by mixing a first positive electrode active material in the form of (provided as) secondary particles and a second positive electrode active material in the form of (provided as) single particles (e.g., each being a whole particle).

[0046] However, if (for example, when) particles of different shapes and / or sizes are mixed to form (or provide) an electrode (for example, an electrode active material), there may be differences in the reaction rate on each (for example, different types or kinds) particle surface and / or there may be substantially non-uniform residual lithium on each (for example, different types or kinds) particle surface, which can accelerate side reactions. In some cases, there may be differences in the reaction rates at the particle interface and inside the particles, which may cause the particles to deteriorate substantially non-uniformly, thereby bringing about problems of generating gas products and increasing battery resistance. Accordingly, some embodiments of the present disclosure include a method of applying a non-aqueous electrolyte as described in more detail herein to a positive electrode to form (or provide) a stable protective layer with high conductivity at the interface of the positive electrode. For example, the protective layer can inhibit or reduce substantially continuous side reactions in the positive electrode, and also effectively inhibit or reduce substantially non-uniform reactions and resistance increases, and control the amount of gas products generated.

[0047] The average particle size (D 50 ) may be larger than the average particle size (D 50 ). In this case, the first positive electrode active material may be represented as (e.g., called) "large particles", and the second positive electrode active material may be represented as (e.g., called) "small particles". By appropriately or properly mixing the secondary particles and the single particles, the capacity and energy density of a rechargeable lithium battery including a nickel-based positive electrode active material may be maximized or increased, and its cycle life characteristics and durability may be improved.

[0048] Average particle size (D 50 ) refers to the diameter of particles accounting for 50% by volume of the cumulative volume in a particle size distribution obtained by randomly measuring the sizes (diameters or major axis lengths) of about 20 particles in a scanning electron microscope image.

[0049] The average particle size (D 50 ) may be, for example, about 10 micrometers (μm) to about 20 μm, about 10 μm to about 18 μm, or about 12 μm to about 16 μm. The average particle size (D 50 ) may be, for example, about 0.5 μm to about 8 μm, about 1 μm to about 7 μm, about 1.5 μm to about 6 μm, or about 2 μm to about 5 μm. If (for example, when) the average particle size of each positive electrode active material satisfies the described range, high capacity and high energy density can be achieved.

[0050] Based on 100 wt% of the total amount of the first positive electrode active material and the second positive electrode active material, the first positive electrode active material may be included in an amount of about 60 wt% to about 95 wt% (e.g., about 70 wt% to about 90 wt%). Based on 100 wt% of the total amount of the first positive electrode active material and the second positive electrode active material, the second positive electrode active material may be included in an amount of about 5 wt% to about 40 wt% (e.g., about 10 wt% to about 30 wt%). If (e.g., when) the mixing ratio of the first positive electrode active material and the second positive electrode active material satisfies the described range, the energy density may be increased while maximizing or increasing the capacity at the same time.

[0051] The lithium nickel composite oxide of the first positive electrode active material and the lithium nickel composite oxide of the second positive electrode active material may be the same or different, and may each independently include (e.g., contain) nickel in an amount greater than or equal to about 70 mol% (e.g., greater than or equal to about 80 mol%, greater than or equal to about 90 mol%, or greater than or equal to about 91 mol%) based on 100 mol% of the total metal excluding lithium (e.g., of the lithium nickel composite oxide). As an example, the lithium nickel composite oxide may be a high nickel oxide, which includes (e.g., contains) greater than or equal to about 80 mol% of nickel based on 100 mol% of the total metal excluding lithium (e.g., of the lithium nickel composite oxide). One or both (e.g., simultaneously) of the first positive electrode active material and the second positive electrode active material may be high nickel positive electrode active materials. In this case, high capacity and high energy density can be achieved while achieving excellent or appropriate charge / discharge efficiency and cycle life characteristics.

[0052] The lithium nickel-based composite oxide of the first positive electrode active material and the lithium nickel-based composite oxide of the second positive electrode active material may be the same as or different from each other, and may each independently be represented by Chemical Formula 11.

[0053] Chemical formula 11

[0054] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0055] 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 may independently be at least one element of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W and Zr (for example, one or more elements selected from the foregoing), and X may be at least one element of F, P and S (for example, one or more elements selected from the foregoing).

[0056] In some embodiments, for Chemical Formula 11, 0.7≤x1≤1, 0≤y1≤0.3, and 0≤z1≤0.3, or 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2, or 0.9≤x1≤1, 0≤y1≤0.1, and 0≤z1≤0.1.

[0057] The lithium nickel-based composite oxide of the first positive electrode active material and the lithium nickel-based composite oxide of the second positive electrode active material may each be independently represented by Chemical Formula 12.

[0058] Chemical formula 12

[0059] Li a2 Ni x2 Co y2 M 3 z2 O 2-b2 X b2

[0060] In Chemical Formula 12, 0.9≤a2≤1.8, 0.3≤x2≤1, 0≤y2≤0.7, 0≤z2≤0.7, 0.9≤x2+y2+z2≤1.1, and 0≤b2≤0.1, M 3Each may independently be at least one element of Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W and Zr (for example, one or more elements selected from the foregoing), and X may be at least one element of F, P and S (for example, one or more elements selected from the foregoing).

[0061] In some embodiments, for Chemical Formula 12, 0.7≤x2≤1, 0≤y2≤0.3, and 0≤z2≤0.3, or 0.8≤x2≤1, 0≤y2≤0.2, and 0≤z2≤0.2, or 0.9≤x2≤1, 0≤y2≤0.1, and 0≤z2≤0.1.

[0062] The second positive electrode active material may be in the form of a single particle, may exist alone without a grain boundary within the particle, may include one particle, or may consist of one particle. The second positive electrode active material may have a single particle, an integral structure, an integral structure, or non-aggregated particles (e.g., where the particles are not aggregated with each other in morphology and exist as independent phases). The second positive electrode active material may be represented as (e.g., referred to as) a "single particle" (integral particle, single crystal), for example, a single crystal.

[0063] Binder

[0064] In some embodiments, if (for example, when) the positive electrode active material layer includes a binder, the binder can improve the bonding properties between the positive electrode active material particles and between the positive electrode active material particles and the positive electrode current collector. Examples of binders may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth) acrylated styrene-butadiene rubber, epoxy resin, (meth) acrylic resin, polyester resin and / or nylon, but are not limited thereto. Based on 100wt% of the positive electrode active material layer, the content (for example, amount) of the binder may be about 0.5wt% to about 5wt%.

[0065] Conductive Materials

[0066] A conductive material may be included to provide electrode conductivity (e.g., an electron conductor), and any suitable conductive material may be used as the conductive material unless it causes a chemical change. Examples of the conductive material may include 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 (such as metal powders or metal fibers including copper, nickel, aluminum, silver, etc.); conductive polymers (such as polyphenylene derivatives); and / or one or more mixtures thereof.

[0067] The content (eg, amount) of the conductive material may be about 0.5 wt % to about 5 wt % based on 100 wt % of the positive electrode active material layer.

[0068] The positive electrode current collector may include Al, but the present disclosure is not limited thereto.

[0069] Negative electrode

[0070] The negative electrode may include a negative electrode current collector and a negative electrode active material layer including a negative electrode active material on the negative electrode current collector, and the negative electrode active material layer may further include a binder, a conductive material, and / or (eg, any appropriate) combination thereof.

[0071] Negative electrode active material

[0072] The negative electrode active material may include 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.

[0073] Examples of materials that can reversibly intercalate / deintercalate lithium ions may include crystalline carbon, amorphous carbon, and / or (e.g., any suitable) combinations thereof as carbonaceous negative electrode active materials. Crystalline carbon may be amorphous or flaky, thin, spherical, or fibrous natural graphite or artificial graphite. Amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0074] The lithium metal alloy may include an alloy of lithium and at least one metal among Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn (for example, one or more metals selected from the foregoing).

[0075] The material capable of being doped / undoped with lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x(0<x≤2), Si-Q alloy (wherein Q is (for example, selected from) alkali metal, alkaline earth metal, 13th group element, 14th group element (excluding Si), 15th group element, 16th group element, transition metal, rare earth element and / or its (for example, any suitable) combination of elements, such as Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po and / or its (for example, any suitable) combination) and / or its (for example, any suitable) combination. The Sn-based negative electrode active material may be Sn, SnO2, SnO x (0<x<2), Sn alloys, and / or (eg, any suitable) combinations thereof.

[0076] The silicon-carbon composite may be a composite of silicon and amorphous carbon (for example, used in a negative electrode (ie, cathode)). The average particle size (D 50 ) may be, for example, about 0.5 μm to about 20 μm. 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 (or provide silicon particles and amorphous carbon coated on the surface of the silicon particles). For example, it may include secondary particles (cores) in which silicon primary particles are aggregated and an amorphous carbon coating (shell) on the surface of the secondary particles. Amorphous carbon may also be present between silicon primary particles, for example, silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed (present) in an amorphous carbon matrix.

[0077] 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. The crystalline carbon may be artificial graphite, natural graphite and / or (e.g., any appropriate) combination thereof. The amorphous carbon may include soft carbon, hard carbon, mesophase pitch carbonization product, calcined coke, etc.

[0078] If (for example, when) the silicon-carbon composite includes silicon and amorphous carbon, the content (for example, amount) of silicon may be about 10 wt% to about 50 wt% and the content (for example, amount) of amorphous carbon may be about 50 wt% to about 90 wt% based on about 100 wt% of the silicon-carbon composite. In one or more embodiments, if (for example, when) the silicon-carbon composite includes silicon, amorphous carbon and crystalline carbon, the content (for example, amount) of silicon may be about 10 wt% to about 50 wt%, the content (for example, amount) of crystalline carbon may be about 10 wt% to about 70 wt%, and the content (for example, amount) of amorphous carbon may be about 20 wt% to about 40 wt% based on about 100 wt% of the silicon-carbon composite.

[0079] In addition, the thickness of the amorphous carbon coating layer may be about 5 nanometers (nm) to about 100 nm. The average particle size (D 50 ) may be about 10 nm to about 1 μm or about 10 nm to about 200 nm. The silicon particles may exist as silicon alone, may exist in the form of (or provide) a silicon alloy, or may exist in an oxidized form of silicon. The oxidized form of silicon may be SiO x (0<x≤2) represents. In some embodiments, the atomic content (e.g., amount) ratio of Si:O (which indicates the degree of oxidation) may be about 99:1 to about 33:67. If (e.g., when) no definition is provided otherwise, the average particle size (D) as used herein is 50 ) indicates the diameter of particles where the cumulative volume in the particle size distribution is about 50 volume %.

[0080] The Si-based negative electrode active material or the Sn-based negative electrode active material may be mixed with the carbon-based negative electrode active material. If (for example, when) the Si-based negative electrode active material or the Sn-based negative electrode active material and the carbon-based negative electrode active material are mixed and used, the mixing ratio may be about 1:99 to about 90:10 by weight.

[0081] Binder

[0082] In some embodiments, the negative electrode includes a binder that can (e.g., for) well bind the negative electrode active material particles to each other and also bind the negative electrode active material to the negative electrode current collector. The binder can be a non-aqueous binder, an aqueous binder, a dry binder, and / or (e.g., any suitable) combination thereof.

[0083] 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 (eg, any suitable) combinations thereof.

[0084] The aqueous binder may include styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol and / or (e.g., any suitable) combination thereof.

[0085] If (for example, when) an aqueous binder is used as a binder in the negative electrode active material layer, a cellulose compound capable of imparting viscosity may be further included. As the cellulose compound, one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose and alkali metal salts thereof may be mixed and used. The alkali metal may be Na, K, Li or (for example, any appropriate) combination thereof.

[0086] 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 (eg, any appropriate) combinations thereof.

[0087] Conductive Materials

[0088] In some embodiments, the negative electrode includes a conductive material that can provide electrode conductivity, and any conductive material can be used as the conductive material unless it causes a chemical change. Examples of conductive materials include: carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.); metal-based materials (such as metal powders or metal fibers including copper, nickel, aluminum, silver, etc.); conductive polymers (such as polyphenylene derivatives); and / or one or more mixtures thereof.

[0089] The content (e.g., amount) of the negative electrode active material may be about 95 wt% to about 99.5 wt% based on about 100 wt% of the negative electrode active material layer, and the content (e.g., amount) of the binder may be about 0.5 wt% to about 5 wt% based on about 100 wt% of the negative electrode active material layer. 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 0.5 wt% to about 5 wt% of the conductive material.

[0090] current collector

[0091] The negative electrode current collector may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) or an alloy thereof, and may be in the form of foil, sheet or foam. The thickness of the negative electrode current collector may be, for example, about 1 μm to about 20 μm, about 5 μm to about 15 μm, or about 7 μm to about 10 μm.

[0092] Non-aqueous electrolyte

[0093] The nonaqueous electrolyte according to some embodiments includes an organic solvent, a lithium salt, and an additive, and the additive includes a bicyclic sulfate compound represented by Chemical Formula 1.

[0094] Chemical formula 1

[0095]

[0096] In Chemical Formula 1, A1, A2, A3 and A4 may be each independently the same as or different from each other, and may each independently be a covalent bond; a substituted or unsubstituted C1-C5 alkylene group; a carbonyl group; or a sulfinyl group, provided that A1 and A2 are not covalent bonds at the same time (e.g., not both are covalent bonds), and A3 and A4 are not covalent bonds at the same time (e.g., not both are covalent bonds).

[0097] additive

[0098] In a non-aqueous electrolyte, during charging and discharging, the aforementioned bicyclic sulfate compound represented by Chemical Formula 1 may have a lower reduction potential (ie, reduced earlier) at a relatively low voltage and may be more easily decomposed than an organic solvent. In some embodiments, the reduced ions and / or free radicals may react with lithium ions to form (or provide) a solid electrolyte interface (SEI) on the surface of the negative electrode. For example, the bicyclic sulfate compound may form (or provide) a complex by coordinating with the transition metal ions of the positive electrode active material, which affects the characteristics of the protective layer formed on the positive electrode surface. In other words, compared with a protective layer formed only by an organic solvent, the complex may help (eg, more easily) form (or provide) a stable modified protective layer having high conductivity and (eg, even after long-term charging and discharging on the positive electrode surface) remaining in a solid state. This solid modified protective layer can effectively block or reduce the entry of organic solvents (eg, organic solvents that solvate lithium ions) into the electrode during lithium ion insertion. The modified protective layer formed by the bicyclic sulfate compound effectively prevents the direct contact of the organic solvent with the positive electrode, improves the reversibility of lithium ion insertion and extraction, and as a result increases the stability of the battery and improves the cycle life characteristics. In one or more embodiments, the solid modified protective layer with high conductivity formed on the positive electrode can suppress or reduce the substantially continuous side reactions and / or cracks of the described nickel-based positive electrode, thereby effectively controlling the gas generation amount and the resistance increase rate. In addition, the bicyclic sulfate compound (wherein multiple rings are bonded in a spiral structure (i.e., in the form)) is thermally stable, and thus can improve the battery cycle life characteristics at high temperatures.

[0099] For example, in Chemical Formula 1, at least one of A1, A2, A3, and A4 (e.g., one or more selected from the above) may be an unsubstituted C1-C5 alkylene or a substituted C1-C5 alkylene. The substituent of the substituted C1-C5 alkylene may be, for example, a halogen, a C1-C20 alkyl substituted or unsubstituted by a halogen, a C2-C20 alkenyl substituted or unsubstituted by a halogen, a C2-C20 alkynyl substituted or unsubstituted by a halogen, a C3-C20 cycloalkenyl substituted or unsubstituted by a halogen, a C3-C20 heterocyclic group substituted or unsubstituted by a halogen, a C6-C40 aryl group substituted or unsubstituted by a halogen, a C2-C40 heteroaryl group substituted or unsubstituted by a halogen, or a polar functional group including (e.g., containing) at least one (e.g., one or more) heteroatom.

[0100] For example, the substituent of the substituted C1-C5 alkylene group may be halogen, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, trifluoromethyl, tetrafluoroethyl, phenyl, naphthyl, tetrafluorophenyl, pyrrolyl or pyridyl.

[0101] As an example, the substituent of the substituted C1-C5 alkylene group may be a polar functional group containing a heteroatom, wherein the heteroatom of the polar functional group may be, for example, halogen, oxygen, nitrogen, phosphorus, sulfur, silicon, boron and / or (for example, any appropriate) combination thereof, and in addition to the heteroatom, the polar functional group may also include C1-C 20 Alkyl, C2~C 20 Alkenyl, C3~C 20 Alkynyl, C3~C 20 Cycloalkyl, C6~C 20 Aryl, C3~C 20 Heteroaryl, C7~C 20 Alkyl aryl, C3~C 20 trialkylsilyl or C7~C 20 Aralkyl. For example, halogen may be F (fluorine).

[0102] For example, the polar functional group is at least one selected from the following: -F, -Cl, -Br, -I, -C(═O)OR 16 、-OR 16 、-OC(═O)OR 16 , -R 15 OC(═O)OR 16 、-C(═O)R 16 , -R 15 C(═O)R 16 、-OC(═O)R 16 , -R 15 OC(═O)R 16 、-C(═O)-OC(═O)R 16 , -R 15 C(═O)-OC(═O)R 16 、-SR 16 , -R 15 SR 16 、-SSR 16 , -R 15 SSR 16 、-S(═O)R 16 , -R 15 S(═O)R 16 , -R 15 C(═S)R 16 , -R 15 C(═S)SR 16 , -R 15 3R 16 、-SO3R 16 、-NNC(═S)R 16 , -R 15 NNC(═S)R 16 , -R 15N═C═S, -NCO, -R 15 -NCO, -NO2, -R 15 NO2, -R 15 S02R 16 、-SO2R 16 ,

[0103]

[0104]

[0105]

[0106]

[0107] Among them, in the above formula, R 11 and R 15 Each of which is independently halogen-substituted or unsubstituted C1-C 20 Alkylene, halogen-substituted or unsubstituted C2~C 20 Alkenylene, halogen-substituted or unsubstituted C2~C 20 Alkyne, halogen-substituted or unsubstituted C3~C 12 Cycloalkylene, halogen-substituted or unsubstituted C6~C 40 Arylene, halogen-substituted or unsubstituted C2~C 40 Heteroarylene, halogen-substituted or unsubstituted C7~C 15 Alkyl arylene or halogen substituted or unsubstituted C7~C 15 aralkylene; and R 12 , R 13 , R 14 and R 16 Each of them is independently hydrogen, halogen, halogen-substituted or unsubstituted C1-C 20 Alkyl, halogen-substituted or unsubstituted C2~C 20 Alkenyl, halogen-substituted or unsubstituted C2~C 20 Alkynyl, halogen-substituted or unsubstituted C3~C 12 Cycloalkyl, halogen-substituted or unsubstituted C6~C 40 Aryl, halogen-substituted or unsubstituted C2~C 40 Heteroaryl, halogen-substituted or unsubstituted C7~C 15 Alkyl aryl, halogen substituted or unsubstituted C7~C 15 trialkylsilyl or halogen substituted or unsubstituted C7~C 15 Aralkyl.

[0108] The aforementioned bicyclic sulfate ester compound represented by Chemical Formula 1 may be represented by Chemical Formula 2 or Chemical Formula 3, for example.

[0109] Chemical formula 2

[0110]

[0111] Chemical formula 3

[0112]

[0113] B1, B2, B3 and B4 in Chemical Formula 2 and D1 and D2 in Chemical Formula 3 may be each independently the same as or different from each other, and may each independently be -C(E1)(E2)-, a carbonyl group or a sulfinyl group, and

[0114] E1 and E2 may be independently the same as or different from each other, and may be independently hydrogen, halogen, C1-C20 alkyl substituted or unsubstituted by halogen, C2-C20 alkenyl substituted or unsubstituted by halogen, C2-C20 alkynyl substituted or unsubstituted by halogen, C3-C20 cycloalkenyl substituted or unsubstituted by halogen, C3-C20 heterocyclyl substituted or unsubstituted by halogen, C6-C40 aryl substituted or unsubstituted by halogen, or C2-C40 heteroaryl substituted or unsubstituted by halogen.

[0115] For example, E1 and E2 may each independently be hydrogen; halogen; C1-C10 alkyl which may be substituted or unsubstituted by halogen; C6-C40 aryl which may be substituted or unsubstituted by halogen; or C2-C40 heteroaryl which may be substituted or unsubstituted by halogen.

[0116] For example, E1 and E2 can each independently be hydrogen, F, Cl, Br, I, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, trifluoromethyl, tetrafluoroethyl, phenyl, naphthyl, tetrafluorophenyl, pyrrolyl, or pyridyl.

[0117] For example, E1 and E2 can each independently be hydrogen, F, methyl, ethyl, trifluoromethyl, tetrafluoroethyl or phenyl.

[0118] The aforementioned bicyclic sulfate ester compound represented by Chemical Formula 1 may be represented by Chemical Formula 4 or Chemical Formula 5, for example.

[0119] Chemical formula 4

[0120]

[0121] Chemical formula 5

[0122]

[0123] R in Formula 4 21 , R22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 And R1, R2, R3 and R4 in Chemical Formula 5 may be independently the same as or different from each other, and may be independently hydrogen, halogen, C1~C20 alkyl substituted or unsubstituted by halogen, C6~C40 aryl substituted or unsubstituted by halogen, or C2~C40 heteroaryl substituted or unsubstituted by halogen.

[0124] For example, R in Formula 4 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 And R1, R2, R3 and R4 in Chemical Formula 5 may each independently be hydrogen, F, Cl, Br, I, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, trifluoromethyl, tetrafluoroethyl, phenyl, naphthyl, tetrafluorophenyl, pyrrolyl or pyridyl.

[0125] For example, R in Formula 4 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 R1, R2, R3 and R4 in Chemical Formula 5 may each independently be hydrogen, F, methyl, ethyl, propyl, trifluoromethyl, tetrafluoroethyl or phenyl.

[0126] The aforementioned bicyclic sulfate compound represented by Chemical Formula 1 may be represented by, for example, at least one (eg, one or more selected from) of Chemical Formulas 6 to 17. For example, one of these, or a mixture of two or more may be used.

[0127] Chemical formula 6

[0128]

[0129] Chemical formula 7

[0130]

[0131] Chemical formula 8

[0132]

[0133] Chemical formula 9

[0134]

[0135] Chemical formula 10

[0136]

[0137] Chemical formula 11

[0138]

[0139] Chemical formula 12

[0140]

[0141] Chemical formula 13

[0142]

[0143] Chemical formula 14

[0144]

[0145] Chemical formula 15

[0146]

[0147] Chemical formula 16

[0148]

[0149] Chemical formula 17

[0150]

[0151] The term "alkyl" or "alkylene" herein refers to a branched or unbranched aliphatic hydrocarbon group. In some embodiments, the alkyl group may be substituted or unsubstituted. The alkyl group may be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclopropyl, cyclopentyl, cyclohexyl or cycloheptyl, but the present disclosure is not limited thereto, and each of them may be substituted or may not be substituted. In one example, the alkyl group may have 1 to 6 carbon atoms. For example, a C1 to C6 alkyl group may be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, pentyl, 3-pentyl, hexyl, etc.

[0152] The term "cycloalkyl" refers to a fully saturated carbocyclic ring or ring system. For example, it may be cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

[0153] The term "alkenyl" refers to a hydrocarbon group containing 2 to 20 carbon atoms and containing at least one carbon-carbon double bond, and may be, for example, vinyl, 1-propenyl, 2-propenyl, 2-methyl-1-propenyl, 1-butenyl, 2-butenyl, cyclopropenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, etc., but the present disclosure is not limited thereto. In one example, the alkenyl group may be substituted or unsubstituted and may have 2 to 40 carbon atoms.

[0154] The term "alkynyl" refers to a hydrocarbon group containing 2 to 20 carbon atoms and containing at least one carbon-carbon triple bond, and may be, for example, ethynyl, 1-propynyl, 1-butynyl, 2-butynyl, but the present disclosure is not limited thereto. In one example, the alkynyl group may be substituted or unsubstituted and may have 2 to 40 carbon atoms.

[0155] The term "aromatic" refers to a ring or ring system having a conjugated π electron system, and includes carbocyclic aromatic groups (e.g., phenyl) and heterocyclic aromatic groups (e.g., pyridyl). The term includes monocyclic or fused polycyclic rings (i.e., rings that share adjacent pairs of atoms), provided that the entire ring system is aromatic.

[0156] The term "aryl" refers to an aromatic ring or ring system (i.e., two or more fused rings sharing two adjacent carbon atoms) in which the ring backbone contains only carbon. If (for example, when) the aryl is a ring system, each ring in the system may be aromatic. For example, aryl includes phenyl, biphenyl, naphthyl, phenanthrenyl, fused tetraphenyl, etc., but the disclosure is not limited thereto. The aryl group may be substituted or unsubstituted.

[0157] The term "heteroaryl" refers to an aromatic ring system having one ring or multiple condensed rings, wherein at least one ring atom is not carbon, i.e., a heteroatom. In a condensed ring system, at least one heteroatom may be present in only one ring. For example, heteroatoms include oxygen, sulfur or nitrogen, but are not necessarily limited thereto. For example, heteroaryl may include furanyl, thienyl, imidazolyl, quinazolinyl, quinolyl, isoquinolyl, quinoxalinyl, pyridyl, pyrrolyl, oxazolyl, indolyl, etc., but the present disclosure is not limited thereto.

[0158] The terms "aralkyl" and "alkylaryl" refer to an aryl group connected by an alkylene group as a substituent, such as an aralkyl group having 7 to 14 carbon atoms, for example, benzyl, 2-phenylethyl, 3-phenylpropyl, naphthylalkyl, etc., but not limited thereto. In one example, the alkylene group may be a lower alkylene group (i.e., an alkylene group having 1 to 4 carbon atoms).

[0159] The “halogen” is an element belonging to Group 17 of the periodic table, and may be, for example, F, Cl, Br, or I, and may be, for example, F.

[0160] Based on 100wt% of the non-aqueous electrolyte, the bicyclic sulfate compound represented by Chemical Formula 1 may be included in an amount of about 0.1wt% to about 3wt% (e.g., about 0.1wt% to about 2.5wt%, about 0.1wt% to about 2wt%, or about 0.5wt% to about 2wt%). If (e.g., when) the content (e.g., amount) of the bicyclic sulfate compound represented by Chemical Formula 1 satisfies the described range, the side reaction and degradation of the positive electrode according to some embodiments may be effectively controlled, and the battery cycle life characteristics may be improved. For example, if (e.g., when) the content (e.g., amount) of the bicyclic sulfate compound represented by Chemical Formula 1 is excessive, the resistance may increase or the cycle life characteristics may deteriorate.

[0161] In addition to the aforementioned bicyclic sulfate ester compound represented by Chemical Formula 1, the additive of the non-aqueous electrolyte may further include other compounds.

[0162] For example, the additive may further include cyclic carbonate.Cyclic carbonate may be for example vinyl ethylene carbonate (VEC), vinylene carbonate (VC), ethylene carbonate, its derivative and / or its (for example, any suitable) combination.The derivative of ethylene carbonate may include for example fluoroethylene carbonate (FEC), difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate and cyanoethylene carbonate.

[0163] In one or more embodiments, the additive may further include succinonitrile (SN), adiponitrile (AN), 1,3,6-hexanetricarbonitrile (HTCN), propene sultone (PST), propane sultone (PS), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), 2-fluorobiphenyl (2-FBP) and / or (e.g., any suitable) combinations thereof.

[0164] Based on 100 wt % of the non-aqueous electrolyte, the additive may be included in an amount of about 0.1 wt % to about 10 wt % (e.g., about 0.5 wt % to about 9 wt %, about 1 wt % to 8 wt %, about 1 wt % to about 7 wt %, about 1 wt % to about 6 wt % or about 2 wt % to about 5 wt %). If (e.g., when) the content (e.g., amount) of the additive satisfies the described range, the cycle life characteristics may be improved, and the gas generation amount and the resistance increase rate may be effectively controlled or selected without adversely affecting the battery.

[0165] Organic solvents

[0166] The organic solvent is used as a medium for transporting ions participating in the electrochemical reaction of the battery. The organic solvent may include a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent, an aprotic solvent, or a combination thereof (eg, any appropriate one).

[0167] Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, valerolactone, caprolactone, etc. Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. In one or more embodiments, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and aprotic solvents may include nitriles (such as R-CN (wherein R is a C2-C20 straight chain, branched or cyclic hydrocarbon group, and includes a double bond, an aromatic ring or an ether bond, etc.)); amides (such as dimethylformamide); dioxolanes (such as 1,3-dioxolane, 1,4-dioxolane, etc.); cyclopentane sulfone, etc.

[0168] The organic solvent may be used alone or in a mixture of two or more types (species), and if (for example, when) two or more types (species) are used in a mixture, the mixing ratio may be appropriately adjusted according to the desired or appropriate battery performance, which is well known to those skilled in the art.

[0169] As an example, the organic solvent may include linear carbonate and / or cyclic carbonate. For example, the organic solvent may include both linear carbonate and cyclic carbonate (for example, at the same time), wherein the volume content (for example, amount) of the linear carbonate may be greater than the volume content of the cyclic carbonate. The volume ratio of linear carbonate and cyclic carbonate may be, for example, about 2: 1 to about 9: 1, about 3: 1 to about 8: 1 or about 4: 1 to about 7: 1.

[0170] The organic solvent may further include an aromatic hydrocarbon organic solvent. For example, a carbonate-based solvent and an aromatic hydrocarbon organic solvent may be mixed and used in a volume ratio of about 1:1 to about 30:1.

[0171] Lithium salts

[0172] The lithium salt dissolved in the organic solvent supplies lithium ions in the battery, ensures the basic operation of the rechargeable lithium battery, and improves the transfer of lithium ions between the positive electrode and the negative electrode. Examples of lithium salts may include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide; LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (wherein x and y are integers of 1 to 20), at least one of lithium tetrafluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFOB) and lithium bis(oxalato)borate (LiBOB) (for example, at least one selected from the foregoing).

[0173] The concentration of the lithium salt may be in the range of about 0.1 M to about 2.0 M. If (eg, when) the concentration of the lithium salt is within the described range, the electrolyte has suitable or appropriate ion conductivity and viscosity, and thus excellent or appropriate performance may be achieved, and lithium ions may be efficiently moved.

[0174] Diaphragm

[0175] Depending on the type or kind of the rechargeable lithium battery, the separator may be present between the positive electrode and the negative electrode. The separator may include a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multilayer film of two or more layers thereof (such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, etc.).

[0176] The membrane may include a porous substrate and a coating on the porous substrate (e.g., on one surface or both surfaces or on one side or both sides (e.g., on opposite surfaces or on opposite sides)), the coating including an organic material, an inorganic material and / or a combination thereof (e.g., any suitable one).

[0177] The porous substrate may be a polymer film formed from any one selected from polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyether ketones, polyarylether ketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene oxides, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers, Teflon and polytetrafluoroethylene, or copolymers or mixtures of two or more thereof.

[0178] The porous substrate may have a thickness of about 1 μm to about 40 μm (eg, about 1 μm to about 30 μm, about 1 μm to about 20 μm, about 5 μm to about 15 μm, or about 10 μm to about 15 μm).

[0179] The organic material may include a (meth)acryl-based copolymer, which includes: a first structural unit derived from (meth)acrylamide; and a second structural unit including at least one of a structural unit derived from (meth)acrylic acid or (meth)acrylate and a structural unit derived from (meth)acrylamide sulfonic acid or its salt.

[0180] The inorganic material may include (e.g., selected from) inorganic particles of Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and / or (e.g., any suitable) combination thereof, but the present disclosure is not limited thereto. The average particle size (D 50 ) may be from about 1 nm to about 2000 nm, for example, from about 100 nm to about 1000 nm or from about 100 nm to about 700 nm.

[0181] 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.

[0182] The coating layer may have a thickness of about 0.5 μm to about 20 μm, for example, about 1 μm to about 10 μm or about 1 μm to about 5 μm.

[0183] Terms such as "substantially," "about," and "approximately" are used as relative terms rather than terms of degree, and are intended to account for the inherent deviations in measured or calculated values ​​that one of ordinary skill in the art would recognize. They may include the stated value and an acceptable range of deviation determined by one of ordinary skill in the art taking into account the limitations and errors associated with the measurement of that amount. For example, "about" may refer to one or more standard deviations, or ±30%, ±20%, ±10%, or ±5% of the stated value.

[0184] The numerical ranges disclosed herein include and are intended to disclose all subranges encompassed by the same numerical precision. For example, a range of "1.0 to 10.0" includes all subranges 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 to 7.6. Therefore, the applicant reserves the right to amend this specification (including the claims) to explicitly set forth any subranges encompassed within the ranges explicitly set forth herein.

[0185] The embodiments and comparative examples of the present disclosure are described in detail herein. However, the following examples are merely examples of the present disclosure, and the present disclosure is not limited to the following examples.

[0186] Example

[0187] Example 1

[0188] 1. Manufacturing of positive electrode

[0189] LiNi 0.91 Co 0.07 Mn 0.01 Al 0.01 The first positive electrode active material is composed of O2, which is in the form of (provided as) secondary particles made by aggregating a plurality of primary particles and has an average particle size (D) of about 12.6 micrometers (μm). 50 ). 0.91 Co 0.07 Mn 0.01 Al 0.01 O2, which has an average particle size (D 50 ) is in the form of a single particle of about 3 μm. The first positive electrode active material and the second positive electrode active material are mixed at a weight ratio of 7:3 to prepare a positive electrode active material.

[0190] 97.7 wt % of a positive electrode active material, 1.3 wt % of a polyvinylidene fluoride (PVDF) binder, and 1.0 wt % of a carbon nanotube conductive material were mixed to prepare a positive electrode active material layer slurry, and the positive electrode active material layer slurry was coated on an aluminum foil current collector, and then dried and roll-pressed to manufacture a positive electrode.

[0191] 2. Fabrication of negative electrode

[0192] 97.5 wt% of graphite negative electrode active material, 1.5 wt% of carboxymethyl cellulose and 1 wt% of styrene-butadiene rubber (SBR) in water solvent were mixed to prepare negative electrode active material layer slurry. The negative electrode active material layer slurry was coated on a copper foil current collector, and then dried and pressed to make a negative electrode.

[0193] 3. Preparation of non-aqueous electrolyte

[0194] The base electrolyte was prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a volume ratio of 2:4:4 to prepare an organic solvent and dissolving LiPF6 lithium salt at a concentration of 1.15 M. Subsequently, 1 wt% of the compound represented by Chemical Formula 6, 1.5 wt% of vinylene carbonate and 0.5 wt% of vinyl ethylene carbonate based on 100 wt% of the non-aqueous electrolyte were added thereto to prepare a non-aqueous electrolyte.

[0195] Chemical formula 6

[0196]

[0197] 4. Manufacturing of rechargeable lithium battery cells

[0198] After a polytetrafluoroethylene separator was inserted between a positive electrode and a negative electrode to manufacture an electrode structure and the electrode structure was inserted into a case, a nonaqueous electrolyte was injected into the case to manufacture a rechargeable lithium battery cell.

[0199] Example 2

[0200] A rechargeable lithium battery cell was manufactured in substantially the same manner as Example 1, except that the first positive electrode active material and the second positive electrode active material were mixed in a ratio (eg, amount) of 8:2 based on parts by weight to manufacture a positive electrode.

[0201] Example 3

[0202] A rechargeable lithium battery cell was manufactured in substantially the same manner as Example 1, except that the first positive electrode active material and the second positive electrode active material were mixed in a ratio (eg, amount) of 9:1 based on parts by weight to manufacture a positive electrode.

[0203] Example 4

[0204] A rechargeable lithium battery cell was manufactured in substantially the same manner as Example 1, except that 0.5 wt % of the compound represented by Chemical Formula 6 was added to the non-aqueous electrolyte.

[0205] Example 5

[0206] A rechargeable lithium battery cell was manufactured in substantially the same manner as Example 1, except that 2 wt % of the compound represented by Chemical Formula 6 was added to the non-aqueous electrolyte.

[0207] Comparative Example 1

[0208] A rechargeable lithium battery cell was manufactured in substantially the same manner as Example 1, except that only the first positive electrode active material was used without using the second positive electrode active material.

[0209] Comparative Example 2

[0210] A rechargeable lithium battery cell was manufactured in substantially the same manner as Example 1, except that only the second positive electrode active material was used without using the first positive electrode active material.

[0211] Comparative Example 3

[0212] A rechargeable lithium battery cell was manufactured in substantially the same manner as Example 1, except that the compound represented by Chemical Formula 6 was not added to the nonaqueous electrolyte.

[0213] Comparative Example 4

[0214] A rechargeable lithium battery cell was manufactured in substantially the same manner as Example 1, except that 5 wt % of the compound represented by Chemical Formula 6 was added to the non-aqueous electrolyte.

[0215] For better understanding, each design of the positive electrode and the non-aqueous electrolyte is briefly shown in Table 1.

[0216] Evaluation Example 1: Evaluation of initial resistance

[0217] The rechargeable lithium battery cells of Examples 1 to 5 and Comparative Examples 1 to 4 were initially charged to an upper limit voltage of 4.25 V at a constant current of 0.2 C at 25° C., and charged to 0.05 C at a constant voltage, and then discharged to a cutoff voltage of 2.8 V at 0.2 C. Subsequently, the battery cells were charged to a potential corresponding to a state of charge (SOC) of 50 (charged to 50% of the charge capacity based on 100% of the entire battery charge capacity) at 0.2 C, and paused for 2 hours, and then the initial DC resistance (also referred to as “initial resistance”) was measured based on a voltage change obtained by applying a current equivalent to 1 C thereto for 10 seconds, and the results are shown in Table 1.

[0218] Evaluation Example 2: Evaluation of the resistance increase rate during high temperature cycle life

[0219] The rechargeable lithium battery cells according to Examples 1 to 5 and Comparative Examples 1 to 4 were charged at 1.0C and discharged at 1.0C in a voltage range of 2.8V to 4.25V at 45°C for 50 or more times after the initial charge and discharge in Evaluation Example 1. After 50 cycles, the DC resistance of the battery cell was remeasured. Then, the resistance increase rate during the high temperature cycle life was calculated by dividing the resistance of the 50th cycle by the initial resistance and multiplying by 100, and the results are shown in Table 1.

[0220] Evaluation Example 3: Evaluation of gas generation

[0221] The rechargeable lithium battery cells of Examples 1 to 5 and Comparative Examples 1 to 4 were charged and discharged for 50 cycles at 45° C. as in Evaluation Example 2, and then the battery cell thickness increase rate was calculated according to Equation 1 and the results are shown in Table 1 to indirectly evaluate the gas generation amount.

[0222] [Equation 1]

[0223] {(battery cell thickness after 50 cycles) - (battery cell thickness before initial charge and discharge)} / (battery cell thickness before initial charge and discharge) × 100

[0224] (Table 1)

[0225]

[0226] Referring to Table 1, Examples 1 to 5 each exhibited a suitable or appropriate initial resistance, and a resistance increase rate during high temperature cycle life of less than or equal to 47.2%, which confirmed excellent or appropriate high temperature cycle life characteristics, and were controlled or selected to have a battery cell thickness increase rate of less than or equal to 36.1%, which confirmed a reduction in gas generation.

[0227] Comparative Example 1 (in Comparative Example 1, only the first positive electrode active material is applied to the positive electrode) exhibits a high resistance increase rate and a high battery cell thickness increase rate during the high temperature cycle life, thereby generating a large amount of gas. Compared with Examples 1 to 5, Comparative Example 2 (in Comparative Example 2, only the second positive electrode active material is applied to the positive electrode) exhibits poor initial resistance, and a high resistance increase rate during the high temperature cycle life, thereby deteriorating the cycle life characteristics. Comparative Example 3 (in Comparative Example 3, the bicyclic sulfate compound is not added to the electrolyte) exhibits an excessively high resistance increase rate during the high temperature cycle life and poor cycle life characteristics, and the battery cell thickness increase rate is too high, thereby generating excessive gas. Comparative Example 4 (5 wt% of the bicyclic sulfate compound is used in Comparative Example 4) exhibits poor initial resistance and a high resistance increase rate during the high temperature cycle life.

[0228] The battery management system (BMS) device and / or any other related device or component according to the embodiments of the present disclosure described herein may be implemented using any appropriate hardware, firmware (e.g., 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 a separate IC chip. In addition, the various components of the device may be implemented on a flexible printed circuit film, a tape carrier package (TCP), or a printed circuit board (PCB), or formed on a substrate. In addition, the various components of the device may be processes or threads running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components to perform the various functions described herein. The computer program instructions are stored in a memory, which may be implemented in a computing device using a standard memory device, such as, for example, a random access memory (RAM). The computer program instructions may also be stored in other non-temporary computer-readable media (such as, for example, a CD-ROM, a flash drive, etc.). Moreover, those skilled in the art should recognize that, without departing from the scope of the present disclosure, the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a dedicated computing device may be distributed on one or more other computing devices.

[0229] While the disclosure has been described in conjunction with what are presently considered to be practical example embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments, but on the contrary is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the claims and their equivalents.

Claims

1. A rechargeable lithium battery comprising: Positive electrode; Negative electrode; Diaphragm; and Non-aqueous electrolyte, The positive electrode comprises: a first positive electrode active material in the form of secondary particles and comprising a lithium nickel-based composite oxide, the secondary particles comprising a plurality of primary particles, the plurality of primary particles being aggregated, and a second positive electrode active material in the form of a single particle and comprising a lithium nickel-based composite oxide, The non-aqueous electrolyte comprises an organic solvent, a lithium salt and an additive, The additive includes a bicyclic sulfate compound represented by Chemical Formula 1: Chemical formula 1 In Chemical Formula 1, A1, A2, A3 and A4 are the same as or different from each other and are each independently a covalent bond, a substituted or unsubstituted C1-C5 alkylene group, a carbonyl group or a sulfinyl group, A1 and A2 are not covalent bonds at the same time, and A3 and A4 are not covalent bonds at the same time.

2. The rechargeable lithium battery of claim 1, wherein An average particle size of the secondary particles of the first positive electrode active material is larger than an average particle size of the individual particles of the second positive electrode active material.

3. The rechargeable lithium battery of claim 1, wherein The average particle size of the secondary particles of the first positive electrode active material is 10 μm to 20 μm, and The average particle size of the single particles of the second positive electrode active material is 0.5 μm to 8 μm.

4. The rechargeable lithium battery of claim 1, wherein The first positive electrode active material includes an amount of 60 wt % to 95 wt % and the second positive electrode active material includes an amount of 5 wt % to 40 wt % based on 100 wt % of the total amount of the first positive electrode active material and the second positive electrode active material.

5. The rechargeable lithium battery of claim 1, wherein The lithium nickel composite oxide of the first positive electrode active material and the lithium nickel composite oxide of the second positive electrode active material are the same as or different from each other, and each independently includes nickel in an amount greater than or equal to 80 mol % based on 100 mol % of the total metal excluding lithium in the lithium nickel composite oxide.

6. The rechargeable lithium battery of claim 1, wherein The lithium nickel-based composite oxide of the first positive electrode active material and the lithium nickel-based composite oxide of the second positive electrode active material are the same as or different from each other, and are each independently represented by Chemical Formula 11: Chemical formula 11 Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 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, 0≤b1≤0.1， M 1 and M 2 Each is independently at least one 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 is at least one element selected from F, P and S.

7. The rechargeable lithium battery of claim 6, wherein In Chemical Formula 11, 0.7≤x1≤1, 0≤y1≤0.3, and 0≤z1≤0.

3.

8. The rechargeable lithium battery of claim 6, wherein In Chemical Formula 11, 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.

2.

9. The rechargeable lithium battery of claim 6, wherein In Chemical Formula 11, 0.9≤x1≤1, 0≤y1≤0.1, and 0≤z1≤0.

1.

10. The rechargeable lithium battery of claim 1, wherein The bicyclic sulfate ester compound is included in an amount of 0.1 wt % to 3 wt % based on 100 wt % of the non-aqueous electrolyte.

11. The rechargeable lithium battery of claim 1, wherein The bicyclic sulfate ester compound is included in an amount of 0.5 wt % to 2 wt % based on 100 wt % of the non-aqueous electrolyte.

12. The rechargeable lithium battery of claim 1, wherein In Chemical Formula 1, at least one selected from A1, A2, A3 and A4 is an unsubstituted C1-C5 alkylene group or a substituted C1-C5 alkylene group, and The substituent of the substituted C1~C5 alkylene group is halogen, C1~C20 alkyl substituted or unsubstituted by halogen, C2~C20 alkenyl substituted or unsubstituted by halogen, C2~C20 alkynyl substituted or unsubstituted by halogen, C3~C20 cycloalkenyl substituted or unsubstituted by halogen, C3~C20 heterocyclic group substituted or unsubstituted by halogen, C6~C40 aryl substituted or unsubstituted by halogen, C2~C40 heteroaryl substituted or unsubstituted by halogen, or a polar functional group including at least one heteroatom.

13. The rechargeable lithium battery of claim 12, wherein In Chemical Formula 1, at least one selected from A1, A2, A3 and A4 is an unsubstituted C1-C5 alkylene group or a substituted C1-C5 alkylene group, and The substituent of the substituted C1-C5 alkylene group is halogen, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, trifluoromethyl, tetrafluoroethyl, phenyl, naphthyl, tetrafluorophenyl, pyrrolyl or pyridyl.

14. The rechargeable lithium battery of claim 1, wherein The bicyclic sulfate compound is represented by Chemical Formula 2 or Chemical Formula 3: Chemical formula 2 Chemical formula 3 B1, B2, B3 and B4 in Chemical Formula 2 are the same as or different from each other and D1 and D2 in Chemical Formula 3 are the same as or different from each other and are each independently -C(E1)(E2)-, a carbonyl group or a sulfinyl group, and E1 and E2 are the same as or different from each other and are each independently hydrogen, halogen, C1-C20 alkyl substituted or unsubstituted by halogen, C2-C20 alkenyl substituted or unsubstituted by halogen, C2-C20 alkynyl substituted or unsubstituted by halogen, C3-C20 cycloalkenyl substituted or unsubstituted by halogen, C3-C20 heterocyclyl substituted or unsubstituted by halogen, C6-C40 aryl substituted or unsubstituted by halogen, or C2-C40 heteroaryl substituted or unsubstituted by halogen.

15. The rechargeable lithium battery of claim 1, wherein The bicyclic sulfate compound is represented by Chemical Formula 4 or Chemical Formula 5: Chemical formula 4 Chemical formula 5 R in Formula 4 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 are the same as or different from each other and R1, R2, R3 and R4 in Chemical Formula 5 are the same as or different from each other and are each independently hydrogen, halogen, C1-C20 alkyl substituted or unsubstituted by halogen, C6-C40 aryl substituted or unsubstituted by halogen, or C2-C40 heteroaryl substituted or unsubstituted by halogen.

16. The rechargeable lithium battery of claim 1, wherein The bicyclic sulfate compound is any one selected from Chemical Formula 6 to Chemical Formula 17: Chemical formula 6 Chemical formula 7 Chemical formula 8 Chemical formula 9 Chemical formula 10 Chemical formula 11 Chemical formula 12 Chemical formula 13 Chemical formula 14 Chemical formula 15 Chemical formula 16 Chemical formula 17 17. The rechargeable lithium battery of claim 1, wherein The additive in the non-aqueous electrolyte includes vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, vinylethylene carbonate, succinonitrile, adiponitrile, 1,3,6-hexanitrile, propylene sultone, propane sultone, lithium tetrafluoroborate, lithium difluorophosphate, 2-fluorobiphenyl or a combination thereof.

18. The rechargeable lithium battery of claim 1, wherein The organic solvent includes a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent, an aprotic solvent or a combination thereof.

19. The rechargeable lithium battery of claim 1, wherein The organic solvent includes chain carbonate and / or cyclic carbonate.

20. The rechargeable lithium battery of claim 1, wherein The organic solvent includes a linear carbonate and a cyclic carbonate, and the volume ratio of the linear carbonate to the cyclic carbonate is 2:1 to 9:1.

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