Separator for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The present disclosure relates to a separator for a rechargeable lithium battery and a rechargeable lithium battery including the same. A separator for a rechargeable lithium battery includes a porous substrate and a coating layer on at least one surface of the porous substrate.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2024-0124443, filed on September 12, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] With the increasing prevalence of battery-powered electronic devices (such as mobile phones, laptops, and electric vehicles), the demand for rechargeable batteries with high energy density and high capacity is growing. Therefore, improving the performance of rechargeable lithium batteries can be advantageous.

[0003] Rechargeable lithium batteries typically include a positive electrode and a negative electrode, as well as an electrolyte. The positive and negative electrodes contain active materials capable of inserting and deintercalating lithium ions. When lithium ions are inserted into or extracted from the positive and negative electrodes, the rechargeable lithium battery generates electrical energy through oxidation and reduction.

[0004] As rechargeable lithium-ion batteries continue to charge and discharge, a series of reactions may occur [structural collapse of the positive electrode active material on the positive electrode surface → elution of transition metal ions, post-transition metal ions, and / or quasi-metal ions from the positive electrode active material into the electrolyte → reduction of ions eluted into the electrolyte on the negative electrode surface → electrodeposition of the reduced ions on the negative electrode surface in the form of transition metals, quasi-metals, and / or their oxides]. Therefore, an unstable solid-electrolyte interface (SEI) film may form on the negative electrode surface, leading to side reactions at the interface between the negative electrode and the electrolyte (e.g., gas generation, increased interfacial resistance, etc.), and potentially reducing the lifespan and / or high-temperature storage characteristics of the rechargeable lithium-ion battery.

[0005] Furthermore, when rechargeable lithium batteries are charged at high voltages or stored at high temperatures (e.g., 60°C or higher), the elution of transition metal ions, post-transition metal ions, and / or quasi-metal ions from the positive electrode active material increases.

[0006] The separator is included between the positive and negative electrodes and is immersed in the electrolyte. Therefore, the separator can capture transition metal ions, post-transition metal ions, and / or quasi-metal ions eluted into the electrolyte, thereby improving the rate of increase in resistance during high-voltage charging or high-temperature storage. Background Technology

[0007] Examples of this disclosure relate to a separator for a rechargeable lithium battery and a rechargeable lithium battery including the separator. Summary of the Invention

[0008] This disclosure describes a separator for a rechargeable lithium battery that captures transition metal ions, post-transition metal ions, and / or quasi-metal ions.

[0009] This disclosure also describes a rechargeable lithium battery including a separator for the rechargeable lithium battery.

[0010] One aspect of this disclosure includes a separator for a rechargeable lithium battery.

[0011] A separator for a rechargeable lithium battery comprises: a porous substrate; and a coating layer located on at least one surface of the porous substrate, wherein the coating layer comprises a compound represented by the following chemical formula 1: Chemical Formula 1: , Among them, R 1 To R 24 As described in the specific implementation details.

[0012] Another aspect of this disclosure includes a rechargeable lithium battery.

[0013] A rechargeable lithium battery includes a positive electrode, a negative electrode, and a separator between the positive and negative electrodes for rechargeable lithium batteries.

[0014] According to one aspect, a separator for rechargeable lithium batteries can capture transition metal ions, post-transition metal ions, and / or quasi-metal ions eluted into the electrolyte, thereby improving the rate of increase in resistance when the rechargeable lithium battery is charged at high voltage or stored at high temperature. Attached Figure Description

[0015] The above and other objects, features, and advantages of this disclosure will become more apparent to those skilled in the art from the detailed description of exemplary embodiments with reference to the accompanying drawings, in which: Figures 1 to 4 This is a schematic diagram illustrating a rechargeable lithium battery according to an example embodiment; Figure 5 The rate of increase in resistance is shown when a battery using a separator according to Example 1 and Comparative Example 1 is stored at 60°C. Figure 5 In the diagram, the X-axis represents the number of storage days (unit: days), the Y-axis represents the rate of increase in resistance (DCIR, or DC internal resistance) (unit: %), ● represents Example 1, and ■ represents Comparison Example 1; and Figure 6 This is a cross-sectional view showing a separator for a rechargeable lithium battery according to an example embodiment. Detailed Implementation

[0016] Hereinafter, exemplary embodiments of the present disclosure are described in detail. However, these embodiments are given by way of example, and the present disclosure is not limited thereto, but is limited only by the scope of the appended claims.

[0017] Unless otherwise stated herein, when a component such as a layer, film, region, or plate is described as being “on” another component, this includes not only the case where the component is “directly on” the other component, but also the case where there is yet another component in between.

[0018] Unless otherwise stated herein, singular expressions may also include plural expressions. Additionally, unless otherwise stated, “A or B” may mean “including A, including B, or including both A and B”.

[0019] As used herein, “the combination of them” can mean a mixture of components, a laminate, a complex, a copolymer, an alloy, a blend, a reaction product, etc.

[0020] In this specification, particle size (D50) refers to the diameter of particles that constitute 50% of the total volume in a particle size distribution. Particle size distribution can be measured by methods known to those skilled in the art. For example, particle size distribution can be measured using a particle size analyzer or by transmission electron microscopy or scanning electron microscopy. Optionally, the D50 value can be obtained after measurement using a measuring device that utilizes dynamic light scattering, data analysis, and counting of particles in each particle size range. Optionally, D50 can be measured by laser diffraction. For example, when measured by laser diffraction, the D50 can be calculated based on 50% of the particle size distribution in the measuring device after dispersing the particles to be measured in a dispersion solvent, introducing them into a commercially available laser diffraction particle size measuring device (e.g., the MT 3000, available from Microtrac), and irradiating them with ultrasound at a power of 60 W at approximately 28 kHz.

[0021] The term "(meth)acryloyl" as used in this specification refers to acryloyl and / or methacryloyl.

[0022] Unless otherwise stated in the specification, "substitution" refers to the use of halogen atoms (F, Cl, Br, or I), hydroxyl groups, C1 to C2 atoms, etc. 20 Alkoxy, nitro, cyano, amino, imino, azide, amidine, hydrazine, hydrazone, carbonyl, carbamoyl, thiol, ester, ether, carboxyl or its salt, sulfonic acid or its salt, phosphoric acid or its salt, C1 to C 20 Alkyl, C2 to C 20 alkenyl, C2 to C 20 alkynyl group, C6 to C 30 Aryl, C3 to C 20 cycloalkyl, C3 to C 20Cycloalkenyl, C3 to C 20 Cycloalkynyl, C2 to C 20 Heterocyclic alkyl, C2 to C 20 Heterocyclic alkenyl, C2 to C 20 A substituent of a heterocyclic alkynyl group or a combination thereof substitutes for at least one hydrogen atom in the compound.

[0023] Unless otherwise stated in the specification, “heterocyclic alkyl,” “heterocyclic alkenyl,” “heterocyclic alkynyl,” and “heterocyclic alkylene” refer to the presence of at least one N, O, S, or P heteroatom in a cyclic compound (such as cycloalkyl, cycloalkenyl, cycloalkynyl, and cycloalkylene).

[0024] Unless otherwise defined in the chemical formula in the specification, when a chemical bond is not drawn where it should be, it means that a hydrogen atom is bonded at that location.

[0025] When describing a range of values ​​in the instruction manual, “X to Y” means “X or greater and Y or less (X ≤ and ≤ Y)”.

[0026] When the terms “about” or “substantially” are used in conjunction with numerical values ​​in this specification, it is intended that the relevant numerical values ​​include a tolerance of ±10% around the stated numerical values.

[0027] When a range is specified, the range includes all values ​​in between, such as increments of 0.1%.

[0028] A separator for a rechargeable lithium battery according to an example embodiment includes a porous substrate and a coating layer on at least one surface of the porous substrate, the coating layer comprising a compound of chemical formula 1 below.

[0029] When rechargeable lithium-ion batteries are charged at high voltages or stored at high temperatures (e.g., 60°C or higher), the compound of Formula 1 can capture transition metal ions, post-transition metal ions, and / or quasi-metal ions that may elute into the electrolyte. Therefore, the separator can reduce or suppress side reactions occurring at the interface between the negative electrode and the electrolyte (e.g., gas generation, increased interfacial resistance, etc.), and improve the lifespan and / or high-temperature storage characteristics of the rechargeable lithium-ion battery.

[0030] According to one example embodiment, transition metal ions, post-transition metal ions, and / or quasi-metal ions can be eluted from the positive electrode active material.

[0031] According to one example embodiment, the compound of Formula 1 may be contained in about 95 wt% or more (e.g., about 95 wt% to about 100 wt% or about 100 wt%) of transition metal ions, post-transition metal ions and / or quasi-metal ion traps contained in the membrane.

[0032] Compounds with chemical formula 1:

[0033] Compounds of Formula 1 can capture transition metal ions, post-transition metal ions, and / or quasi-metal ions present in electrolytes.

[0034] For example, compounds of Formula 1 can capture at least one of silicon (Si) ions, titanium (Ti) ions, vanadium (V) ions, chromium (Cr) ions, manganese (Mn) ions, iron (Fe) ions, cobalt (Co) ions, nickel (Ni) ions, copper (Cu) ions, zinc (Zn) ions, scandium (Sc) ions, and combinations thereof present in an electrolyte.

[0035] For example, compounds of Formula 1 may be significantly advantageous in capturing at least one of cobalt (Co) ions, nickel (Ni) ions, manganese (Mn) ions, and combinations thereof.

[0036] Here, ions or combinations thereof may be derived from the positive electrode active material and / or present in the electrolyte due to external factors. When the rechargeable lithium battery is charged at a high voltage or stored at a high temperature (e.g., 60°C or higher), ions or combinations thereof may be eluted into the electrolyte, but this disclosure is not limited thereto.

[0037] Therefore, the separator can improve the lifespan and / or high-temperature storage characteristics of rechargeable lithium batteries by reducing the deposition of ions or combinations thereof on the surface of the negative electrode. This effect is observed regardless of the type of positive electrode active material, the operating temperature of the rechargeable lithium battery, or its upper limit charging voltage.

[0038] Here, "capture" can be attributed to the coordination bond between the compound represented by Formula 1 and the ion. For example, through the coordination bond between the compound represented by Formula 1 and the ion, the compound represented by Formula 1 can be transformed into a coordination compound represented by any of the following Formulas 1-1 to 1-10: Chemical formula 1-1: .

[0039] Chemical formula 1-2: .

[0040] Chemical formulas 1-3: .

[0041] Chemical formulas 1-4: .

[0042] Chemical formulas 1-5: .

[0043] Chemical formulas 1-6: .

[0044] Chemical formulas 1-7: .

[0045] Chemical formulas 1-8: .

[0046] Chemical formulas 1-9: .

[0047] Chemical formulas 1-10: .

[0048] In chemical formulas 1-1 to 1-10, R 1 To R 24 With R in chemical formula 1 1 To R 24 same.

[0049] Compared to rechargeable lithium batteries that contain compounds of Formula 1 in the electrolyte rather than in the coating, rechargeable lithium batteries that include a separator with a coating containing compounds of Formula 1 have further advantages in reducing or preventing the increase in electrolyte viscosity due to the addition of compounds.

[0050] Meanwhile, in chemical formula 1, R 1 To R 24 Each can be an independent hydrogen atom, halogen atom, substituted or unsubstituted C1-C atom. 20 Alkyl, substituted or unsubstituted C6-C 20 aryl or substituted or unsubstituted C6-C 20 Heterocyclic alkyl groups.

[0051] For example, R 1 To R 24 It can consist entirely of hydrogen atoms. In this case, the compound represented by chemical formula 1 can be represented by the following chemical formula 1A: Chemical Formula 1A: .

[0052] The compound of Formula 1 may be included in the coating layer in the range of about 0.01 wt% to about 3 wt%. Within this range, the compound of Formula 1 can more effectively capture transition metal ions, post-transition metal ions and / or quasi-metal ions that dissociate in the electrolyte, thereby improving the rate of increase in resistivity.

[0053] Compounds of Formula 1 may be included in the coating layer. By including compounds of Formula 1 in the coating layer, compounds of Formula 1 may be advantageous in ensuring the permeability of the membrane.

[0054] According to one example embodiment, the compound of Formula 1 may be dispersed in the coating layer or present on the outermost surface of the coating layer.

[0055] Porous substrate: Porous substrates can be or include substrates having multiple pores and are typically used in electrochemical devices. Porous substrates can be, or include, polymer membranes formed from or comprising, any one or more of the following polymers or copolymers or mixtures thereof: polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, glass fiber, Teflon, and polytetrafluoroethylene.

[0056] The porous substrate can be or includes, for example, a polyolefin substrate comprising polyolefins, and the polyolefin substrate can contribute to improved battery safety due to desired or improved shut-off functionality. The polyolefin substrate can be or includes at least one of, for example, polyethylene monolayer membranes, polypropylene monolayer membranes, polyethylene / polypropylene bilayer membranes, polypropylene / polyethylene / polypropylene trilayer membranes, and polyethylene / polypropylene / polyethylene trilayer membranes. Additionally, the polyolefin resin can include non-olefin resins other than olefin resins or copolymers of olefin monomers and non-olefin monomers.

[0057] Porous substrates can have a thickness ranging from about 1 μm to about 40 μm (e.g., 1 μm to 30 μm, 1 μm to 20 μm or 5 μm to 15 μm).

[0058] Coating layer: The coating may also include any binder that does not affect the trapping effect of the compound of Formula 1, without limitation.

[0059] The adhesive may include one or more of water-based adhesives and organic adhesives.

[0060] According to one example embodiment, the waterborne adhesive may include at least one of the following: carboxyl cellulose or a salt thereof, such as carboxymethyl cellulose or a salt thereof; one or more copolymers of (meth)acrylic acid, (meth)acrylate, (meth)acrylonitrile, and (meth)acrylamide; and one or more diene rubbers. For example, the waterborne adhesive may include at least one of carboxymethyl cellulose or a salt thereof, polyvinyl alcohol, polyacrylic acid, styrene-butadiene rubber, and carboxyl-modified styrene-butadiene rubber.

[0061] According to one example embodiment, the organic adhesive may include one or more of polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene.

[0062] One or more of the aqueous and organic binders may have a weight-average molecular weight in the range of about 10,000 g / mol to about 500,000 g / mol (e.g., 10,000 g / mol, 50,000 g / mol, 100,000 g / mol, 150,000 g / mol, 200,000 g / mol, 250,000 g / mol, 300,000 g / mol, 350,000 g / mol, 400,000 g / mol, 450,000 g / mol, 500,000 g / mol, 70,000 g / mol to 75,000 g / mol). Within this range, it may be possible to exhibit the trapping effect of compounds of Formula 1. Here, "weight-average molecular weight" can be obtained as a polystyrene conversion value by gel permeation chromatography.

[0063] The compound of Formula 1 may be included in the coating layer in the range of about 0.01 wt% to about 3 wt%. Within this range, the compound of Formula 1 can effectively capture transition metal ions, post-transition metal ions and / or quasi-metal ions that dissociate in the electrolyte, thereby achieving the effect of improving the DC resistance increase rate. For example, compounds of formula 1 can be present in amounts of approximately 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, 0.5 wt%, 0.55 wt%, 0.6 wt%, 0.65 wt%, 0.7 wt%, 0.75 wt%, 0.8 wt%, 0.85 wt%, 0.9 wt%, 0.95 wt%, 1 wt%, 1.05 wt%, 1.1 wt%, 1.15 wt%, 1.2 wt%, 1.25 wt%, 1.3 wt%, 1.35 wt%, 1.4 wt%, 1.45 wt%, 1.5 wt%, 1.5 wt%. The range of 5wt%, 1.6wt%, 1.65wt%, 1.7wt%, 1.75wt%, 1.8wt%, 1.85wt%, 1.9wt%, 1.95wt%, 2wt%, 2.05wt%, 2.1wt%, 2.15wt%, 2.2wt%, 2.25wt%, 2.3wt%, 2.35wt%, 2.4wt%, 2.45wt%, 2.5wt%, 2.55wt%, 2.6wt%, 2.65wt%, 2.7wt%, 2.75wt%, 2.8wt%, 2.85wt%, 2.9wt%, 2.95wt%, 3wt%, about 1wt% to about 3wt%, or 1wt% to 2wt% is included in the coating.

[0064] The coating may also include one or more of organic and inorganic fillers known to those skilled in the art. Both organic and inorganic fillers may be common types known to those skilled in the art.

[0065] The coating layer can have a thickness in the range of about 0.01 μm to about 20 μm, and can have a thickness of 1 μm to 5 μm in that range.

[0066] The diaphragm can be formed by applying a composition for forming a coating layer to one or both surfaces of a porous substrate. The composition for forming the coating layer may include: a compound of formula 1; and one or more of an aqueous binder and an organic binder.

[0067] Figure 6 This is a cross-sectional view showing a separator for a rechargeable lithium battery according to an example embodiment. (Refer to...) Figure 6The separator for a rechargeable lithium battery includes a porous substrate 1 and a coating layer 2 located on two surfaces of the porous substrate 1. The coating layer 2 may include a compound of formula 1 (not shown).

[0068] Rechargeable lithium batteries According to one example embodiment, a rechargeable lithium battery includes a separator, a positive electrode, and a negative electrode. The separator for the rechargeable lithium battery refers to the description above. The separator for the rechargeable lithium battery may be positioned between the positive electrode and the negative electrode.

[0069] The positive electrode for a rechargeable lithium battery may include a current collector and a layer of positive electrode active material on the current collector. The positive electrode active material layer may include positive electrode active material and may also include a binder and / or conductive material. For example, the positive electrode may also include additives that can constitute a sacrificial positive electrode.

[0070] The positive electrode active material may include compounds capable of intercalating and deintercalating lithium (lithiation intercalation compounds). For example, at least one of lithium and a composite oxide of a metal (such as or including at least one of cobalt, manganese, nickel and combinations thereof) may be used.

[0071] The composite oxide can be or includes lithium transition metal composite oxides. Examples of composite oxides may include at least one of lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium nickel cobalt manganese oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese oxides, and combinations thereof.

[0072] As an example, the following compounds, represented by any of the following chemical formulas, can be used. Li a A 1-b X b O 2- c D c (0.90≤a≤1.8, 0≤b≤0.5, and 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, and 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, and 0<α<2); Li a Ni 1-b-c Mn bX c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 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, and 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90 ≤ a ≤ 1.8, and 0 ≤ g ≤ 0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); or Li a FePO4 (0.90≤a≤1.8).

[0073] In the above chemical formulas, A is or includes at least one of Ni, Co, Mn, and combinations thereof; X is or includes at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is or includes at least one of O, F, S, P, and combinations thereof; G is or includes at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; and L 1 It is or includes at least one of Mn, Al and combinations thereof.

[0074] The positive electrode active material can be, or includes, for example, a high-nickel positive electrode active material, based on 100 mol% of metals other than lithium in a lithium transition metal complex oxide. The high-nickel positive electrode active material has a nickel content greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol%. High-nickel positive electrode active materials can achieve high capacity and can be used in high-capacity, high-density rechargeable lithium batteries.

[0075] Based on a 100 wt% positive electrode active material layer, the amount of positive electrode active material can range from about 90 wt% to about 99.5 wt%. Based on a 100 wt% positive electrode active material layer, the amounts of binder and conductive material can each range from about 0.5 wt% to about 5 wt%.

[0076] The binder causes the positive electrode active material particles to adhere to each other and to adhere the positive electrode active material to the current collector. As a non-limiting example, examples of binders may include at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, nylon, etc.

[0077] Conductive materials can impart electrical conductivity (e.g., conductivity) to electrodes. Any material that does not cause adverse chemical changes in the battery (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used. Examples of conductive materials may include: carbon-based materials, such as or including at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials, including at least one of copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers, such as polyethylene derivatives; or mixtures thereof.

[0078] Al can be used as a current collector, but is not limited to this.

[0079] The negative electrode for a rechargeable lithium battery may include a current collector and a layer of negative electrode active material on the current collector. The negative electrode active material layer may include a negative electrode active material and may also include a binder and / or a conductive material (e.g., an electrically conductive material).

[0080] For example, the negative electrode active material layer may include from about 90 wt% to about 99 wt% of a negative electrode active material, from about 0.5 wt% to about 5 wt% of a binder, and from about 0 wt% to about 5 wt% of a conductive material.

[0081] The negative electrode active material may include at least one of a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / de-doping lithium, and a transition metal oxide.

[0082] The material capable of reversibly intercalating / deintercalating lithium ions may include a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be graphite, such as natural graphite or artificial graphite having no specified shape, flaky, lamellar, spherical, or fibrous. The amorphous carbon may be or include at least one of soft carbon, hard carbon, mesophase pitch carbonized product, calcined coke, etc.

[0083] The lithium metal alloy includes an alloy of lithium and a metal (such as or including at least one of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn).

[0084] The material capable of doping / de-doping lithium may be or include 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), a Si-Q alloy (where Q is or includes at least one of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element (excluding Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and a combination thereof). The Sn-based negative electrode active material may include at least one of Sn, SnO2, a Sn-based alloy, and a combination thereof.

[0085] The silicon-carbon composite may be or include a composite of silicon and amorphous carbon. According to an exemplary embodiment, the silicon-carbon composite may be in the form of silicon particles and an amorphous carbon coating 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 layer (shell) on the surface of the secondary particles. The 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.

[0086] The silicon-carbon composite may also include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer on the surface of the core.

[0087] The Si-based negative electrode active material or the Sn-based negative electrode active material may be used in combination with the carbon-based negative electrode active material.

[0088] The binder can adhere the negative electrode active material particles to each other, and can also adhere the negative electrode active material to the current collector. The binder can include non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0089] Non-aqueous adhesives may include at least one of polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, and combinations thereof.

[0090] The waterborne adhesive may be or include at least one of styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0091] When an aqueous binder is used as the negative electrode binder, it may further include a cellulose compound capable of imparting viscosity. The cellulose compound may include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts. The alkali metal may include at least one of Na, K, and Li.

[0092] Dry adhesives can be or include polymeric materials that can be fibrous. For example, dry adhesives can be or include at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and combinations thereof.

[0093] Conductive materials can impart electrical conductivity (e.g., conductivity) to electrodes. Any material that does not cause chemical changes in the battery (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used. Non-limiting examples may include: carbon-based materials, such as at least one of natural graphite, synthetic graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials, including at least one of copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0094] The negative electrode current collector may include at least one of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with a conductive metal, and combinations thereof.

[0095] Rechargeable lithium batteries may also include an electrolyte.

[0096] Electrolytes used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0097] Non-aqueous organic solvents can serve as media for transporting ions that participate in the electrochemical reactions of a battery.

[0098] Non-aqueous organic solvents may be or include at least one of carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, and combinations thereof.

[0099] Carbonate solvents may include at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC).

[0100] Ester solvents may include at least one of the following: methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, caprolactone, etc.

[0101] Ether solvents may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Additionally, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc. Aprotic solvents may include at least one of the following: nitriles, such as R-CN (wherein R is a C2 to C20 straight-chain, branched, or cyclic hydrocarbon group, and may include double bonds, aromatic rings, or ether bonds, etc.); amides, such as dimethylformamide; dioxolane, such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolane, etc.

[0102] Non-aqueous organic solvents can be used alone or in combination of two or more solvents.

[0103] In addition, when using carbonate solvents, cyclic carbonates and chain carbonates can be mixed, and the cyclic carbonates and chain carbonates can be mixed in a volume ratio ranging from about 1:1 to about 1:9.

[0104] Lithium salts dissolved in organic solvents supply lithium ions in batteries, enabling rechargeable lithium batteries to operate and improving lithium ion transport between the positive and negative electrodes. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide, LiFSI), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F 2y+1 At least one of the following: (SO2) (where x and y are integers in the range of 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0105] According to one example embodiment, the electrolyte may include at least one of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) as a non-aqueous organic solvent, and may include LiPF6 as a lithium salt.

[0106] According to one example embodiment, based on a total volume of 100 vol% of the non-aqueous organic solvent in the electrolyte, ethylene carbonate (EC) may be included in an amount ranging from about 1 vol% to about 30 vol%, ethyl methyl carbonate (EMC) may be included in an amount ranging from about 20 vol% to about 60 vol%, and dimethyl carbonate (DMC) may be included in an amount ranging from about 20 vol% to about 60 vol%.

[0107] According to one example embodiment, the concentration of lithium salt in the electrolyte can be in the range of about 0.1M to about 2.0M.

[0108] According to one example embodiment, the electrolyte may include a complex represented by at least one of the chemical formulas 1-1 to 1-10 discussed above.

[0109] Based on their shape, rechargeable lithium batteries can be classified as cylindrical batteries, prismatic batteries, pouch batteries, or coin-shaped batteries, etc. Figures 1 to 4 This is a schematic diagram illustrating a rechargeable lithium battery according to an example embodiment. Figure 1 A cylindrical battery is shown. Figure 2 A prismatic battery is shown. Figure 3 and Figure 4 A pouch-type battery is shown. (See reference.) Figures 1 to 4The rechargeable lithium battery 100 may include an electrode assembly 40 and a housing 50. The electrode assembly 40 includes a separator 30 between a positive electrode 10 and a negative electrode 20, and the electrode assembly 40 is housed within the housing 50. 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 of the sealed housing 50. Figure 2 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive terminal 12 connected to the positive electrode lead connector 11, a negative electrode lead connector 21, and a negative terminal 22 connected to the negative electrode lead connector 21. For example... Figure 3 and Figure 4 As shown, the rechargeable lithium battery 100 may include Figure 4 The electrode terminals 70 shown in the figure, or for example... Figure 3 The positive electrode terminal 71 and negative electrode terminal 72 shown in the figure form an electrical path for guiding the current formed in the electrode assembly 40 to the outside of the rechargeable lithium battery 100.

[0110] As a non-limiting example, the rechargeable lithium battery according to the example embodiment can be used in, for example, automobiles, mobile phones and / or various types of electronic devices.

[0111] Examples and comparative examples of this disclosure are described below. However, the following examples are merely illustrative of this disclosure, and this disclosure is not limited thereto.

[0112] Example 1 A composition for coating is prepared comprising polyvinylidene fluoride (PVDF) as a binder and a compound of chemical formula 1A.

[0113] A polyethylene membrane (thickness: 18 μm, SK) serving as a porous substrate is coated with a composition for the coating layer to a thickness of 1 μm on both surfaces using a molding process, and then dried in an oven at 80°C for 16 hours to form a coating layer. This produces a separator for a rechargeable lithium-ion battery, consisting of a first coating layer (thickness: 1 μm) comprising a compound of Formula 1A and a PVDF binder, a porous substrate (thickness: 18 μm), and a second coating layer (thickness: 1 μm) comprising a compound of Formula 1A and a PVDF binder. The compound of Formula 1A is included in the first coating layer at 1 wt%, and the compound of Formula 1A is included in the second coating layer at 1 wt%.

[0114] Example 2 The membrane is manufactured in the same manner as in Example 1, except that the content of the compound of formula 1A in the first coating layer is changed to 1.5 wt%, and the content of the compound of formula 1A in the second coating layer is changed to 1.5 wt%.

[0115] Comparison Example 1 The membrane is manufactured in the same manner as in Example 1, except that the content of the compound of chemical formula 1A in the first coating layer is changed to 0 wt%, and the content of the compound of chemical formula 1A in the second coating layer is changed to 0 wt%.

[0116] Manufacturing of rechargeable lithium batteries (1) Manufacturing of the positive electrode A slurry of positive electrode active material was prepared by mixing 97.7 wt% of positive electrode active material, 1.3 wt% of polyvinylidene fluoride and 1.0 wt% of carbon nanotube conductive material. This slurry was then applied to an aluminum foil current collector, dried, and rolled to produce a positive electrode.

[0117] (2) Manufacturing of the negative electrode A negative electrode active material slurry was prepared by mixing 97.6 wt% graphite negative electrode active material, 1.6 wt% carboxymethyl cellulose, and 0.8 wt% styrene-butadiene rubber in an aqueous solvent. The negative electrode active material slurry was then coated onto a copper foil current collector, dried, and rolled to produce the negative electrode.

[0118] (3) Preparation of electrolyte An electrolyte was prepared by mixing LiPF6 lithium salt at a concentration of 1.15 M in an organic solvent containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 20:40:40, and further dissolving the transition metal salts listed in Table 1 below.

[0119] (4) Manufacturing of rechargeable lithium batteries An electrode assembly is prepared by assembling each of the positive and negative electrodes prepared above, as well as the separators in the example and comparative examples, and then placing them into a prismatic housing. An electrolyte is then added to the housing to fabricate a battery.

[0120] Evaluation Example 1: Increase in DC internal resistance of rechargeable lithium batteries based on days of high-temperature storage (unit: %) For rechargeable lithium-ion batteries comprising separators from Examples 1 and 2, and Comparative Example 1, respectively, high-temperature storage characteristics were evaluated using the following method. The results are shown in Table 1 below. Figure 5 middle.

[0121] After measuring the initial DC internal resistance (DC-IR) as the value of ΔV / ΔI (voltage change / current change), the battery's maximum energy state is taken as the state of full charge (SOC 100%). After storing the battery at high temperature (60°C) for 90 days, the DC internal resistance is measured, and then the DC-IR increase rate (%) is calculated using Equation 1 below: Equation 1: DC-IR increase rate [%] = (DC-IR after 90 days of high-temperature storage / initial DC-IR) × 100 Evaluation Example 2: Amount of metal deposits on the surface of the negative electrode after high-temperature storage of a rechargeable lithium battery (unit: ppm) For the rechargeable lithium-ion batteries comprising separators from Examples 1 and 2, and Comparative Example 1, respectively, after being stored at high temperature for 90 days using the method of Evaluation Example 1, the batteries were disassembled and the amounts of transition metals, post-transition metals, quasi-metals, and / or their oxides deposited on the surface of the negative electrode were measured. The results are listed in Table 1 below.

[0122] Here, after the battery was disassembled at 100% SOC, the amount of transition metals, post-transition metals, quasi-metals and / or their oxides deposited on the surface of the negative electrode was measured using an inductively coupled plasma mass spectrometer (ICP, manufacturer: Horiba Corp., device name: Ultima2).

[0123] Table 1:

[0124]

[0125] As shown in Table 1 above, the example separator for rechargeable lithium-ion batteries has the effect of capturing transition metal ions, post-transition metal ions, and / or quasi-metal ions eluted into the electrolyte. Therefore, it can be concluded that the example separator can improve the rate of increase in resistance when the rechargeable lithium-ion battery is charged at high voltage or stored at high temperature.

[0126] However, compared to the example separator, the comparative example separator exhibits a higher rate of increase in resistance and a higher amount of metal deposition on the negative electrode surface after storing the rechargeable lithium battery at high temperatures.

[0127] While exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited thereto, and various modifications may be made within the scope of the claims, detailed description and drawings, and such modifications also fall within the scope of the present disclosure.

Claims

1. A separator for a rechargeable lithium battery, the separator comprising: Porous substrate; as well as A coating layer is located on at least one surface of the porous substrate. The coating layer comprises a compound represented by chemical formula 1: Chemical Formula 1: ； Among them, R 1 To R 24 Each independently includes a hydrogen atom, a halogen atom, and substituted or unsubstituted C1-C atoms. 20 Alkyl, substituted or unsubstituted C6-C 20 aryl groups and substituted or unsubstituted C6-C 20 One of the heterocyclic alkyl groups.

2. The diaphragm according to claim 1, wherein, In chemical formula 1, R 1 To R 24 It consists entirely of hydrogen atoms.

3. The diaphragm according to claim 1, wherein, The compound of Formula 1 is included in the coating in the range of 0.01 wt% to 3 wt%.

4. The diaphragm according to claim 1, wherein, The compound of Formula 1 is included in 95 wt% or more of the transition metal ions, post-transition metal ions and quasi-metal ion scavengers contained in the membrane.

5. The diaphragm according to claim 4, wherein, The trapping agent traps at least one of silicon ions, titanium ions, vanadium ions, chromium ions, manganese ions, iron ions, cobalt ions, nickel ions, copper ions, zinc ions, scandium ions, and combinations thereof.

6. The diaphragm according to claim 1, wherein, The compound of chemical formula 1 is one of the following: Dispersed in the coating layer; and It exists on the outermost surface of the coating layer.

7. The diaphragm according to claim 1, wherein, The compound of chemical formula 1 is included in the coating layer in the range of 1 wt% to 3 wt%.

8. The diaphragm according to claim 1, wherein, The coating layer also includes one or more of water-based adhesives and organic adhesives.

9. The diaphragm according to claim 8, wherein, One or more of the aqueous binder and the organic binder have a weight-average molecular weight in the range of 10,000 g / mol to 500,000 g / mol.

10. The diaphragm according to claim 8, wherein, The adhesive comprises: Carboxyalkyl cellulose or its salts; One or more copolymers of (meth)acrylic acid, (meth)acrylate, (meth)acrylonitrile and (meth)acrylamide; Diene rubbers; and One or more of polyvinylidene fluoride and polyvinylidene fluoride-hexafluoropropylene.

11. A rechargeable lithium battery, said rechargeable lithium battery comprising: Positive electrode; negative electrode; as well as The diaphragm according to any one of claims 1 to 10 is located between the positive electrode and the negative electrode.

12. The rechargeable lithium battery according to claim 11, wherein, The positive electrode includes a positive electrode active material, which comprises at least one of lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium nickel cobalt manganese oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese oxides, and combinations thereof.

13. The rechargeable lithium battery according to claim 11, wherein the rechargeable lithium battery further comprises an electrolyte.

14. The rechargeable lithium battery according to claim 13, wherein, The electrolyte includes at least one of ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate as a non-aqueous organic solvent.

15. The rechargeable lithium battery according to claim 14, wherein, The electrolyte comprises, relative to 100 vol% of the total volume of the non-aqueous organic solvent, 1 vol% to 30 vol% of the ethylene carbonate, 20 vol% to 60 vol% of the methyl ethyl carbonate and 20 vol% to 60 vol% of the dimethyl carbonate.

16. The rechargeable lithium battery according to claim 13, wherein, The electrolyte comprises 0.1M to 2.0M lithium salt.

17. The rechargeable lithium battery according to claim 13, wherein, The electrolyte comprises one or more of the complexes represented by any one of chemical formulas 1-1 to 1-10: Chemical formula 1-1: ； Chemical formula 1-2: ； Chemical formulas 1-3: ； Chemical formulas 1-4: ； Chemical formulas 1-5: ； Chemical formulas 1-6: ； Chemical formulas 1-7: ； Chemical formulas 1-8: ； Chemical formulas 1-9: ； as well as Chemical formulas 1-10: ； In chemical formulas 1-1 to 1-10, R 1 To R 24 With R in chemical formula 1 1 To R 24 same.

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