Cathode, manufacturing method therefor and secondary battery comprising same

Abstract

A cathode, a manufacturing method therefor and a secondary battery comprising same are provided. The cathode comprises an active material and a binder, wherein the cathode further comprises a binder aid, the binder aid includes an emulsion polymerization functional polymer, the emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60 °C o 200 °C, and the cathode has a carbon uniformity coefficient of 12 to 30. By including the binder aid, excellent physical properties such as tensile strength are exhibited and, simultaneously, the distribution of the binder aid in the cathode is controlled such that an eco-friendly cathode can be manufactured, and a battery comprising the cathode can have improved performance such as capacity and lifespan characteristics.

Description

Anode, method of manufacturing the same, and secondary battery including the same

[0001] The present application claims the benefit of priority based on Korean Patent Application No. 10-2025-0040090 filed March 28, 2025 and Korean Patent Application No. 10-2026-0050226 filed March 20, 2026, and includes all contents disclosed in the documents of said Korean patent applications as part of the specification.

[0002] The present invention relates to a positive electrode, a method for manufacturing the same, and a secondary battery including the same. Specifically, the invention relates to a positive electrode including a binder auxiliary agent, a method for manufacturing the same, and a secondary battery including the same. More specifically, the invention relates to a positive electrode comprising an active material and a binder, wherein the positive electrode further comprises a binder auxiliary agent, the binder auxiliary agent comprises an emulsion polymerization functional polymer, the emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, and the positive electrode has a carbon uniformity coefficient of 12 to 30, a method for manufacturing the same, and a secondary battery including the same.

[0003] With the increasing technological development and demand for mobile devices, the demand for rechargeable batteries as an energy source is rapidly rising. Among these rechargeable batteries, lithium-ion batteries, which possess high energy density and voltage, long cycle life, and low self-discharge rates, have been commercialized and are widely used.

[0004] Generally, such secondary batteries are structured such that an electrolyte containing a lithium salt is impregnated into an electrode assembly in which a porous separator is interposed between a positive electrode and a negative electrode, each having an active material coated on a metal current collector, and each electrode is manufactured by coating an active material layer containing the respective active material onto a metal current collector.

[0005] Therefore, the lifespan characteristics of a secondary battery are primarily determined by how long the electrochemical characteristics of the electrode, particularly the active material layer, are maintained. However, in the case of conventional secondary batteries, there have been many instances where the lifespan characteristics of the secondary battery deteriorate due to the active material layer peeling off from the metal current collector at the electrode following long-term use.

[0006] To solve these problems, a binder has been introduced that can improve the adhesion between the active material layers and the metal current collector, as well as the composition between each active material layer. Fluorinated polymers such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVdF) are mainly used as binders, as they enable the manufacture of free-standing electrodes and improve adhesion to the current collector. However, since the above-mentioned fluorinated polymers are substances with environmentally harmful properties, and regulatory movements are beginning worldwide, research is being conducted on binder materials that can replace them.

[0007] Styrene butadiene rubber (SBR) and the like have been proposed as binder materials that can replace the above-mentioned fluorine-based polymer. However, in order to enable the freestanding of the electrode, a large amount of fluorine-based polymer must still be included, and there is a limitation in that electrode manufacturing is only possible in a wet manner because the above-mentioned alternative materials are not evenly mixed with the components of other active material layers to the extent that they can be applied to the battery for dry electrode manufacturing.

[0008] In the above wet manufacturing method, components such as the active material and binder within the electrode active material layer are mixed with a solvent to form a fluid slurry, and an electrode is manufactured by coating it onto a current collector. In electrodes manufactured using this wet method, a migration phenomenon occurs in which the binder material moves to the surface layer due to the evaporation of the solvent during slurry drying. Consequently, the binder material within the electrode is not evenly distributed in the direction of the electrode thickness, and a larger amount is concentrated on the surface of the electrode active material layer, resulting in a problem where sufficient adhesion between the electrode active material layer and the current collector is not secured.

[0009] Accordingly, there is a need to develop an electrode that can improve the adhesion of the active material layer by enabling the manufacture of an eco-friendly electrode using a material that can replace fluorine-based polymers as a binder, while also exhibiting properties that allow for free-standing even with dry manufacturing.

[0010] [Prior Art Literature]

[0011] [Patent Literature]

[0012] (Patent Document 1) International Publication No. 2024-110976

[0013] The objective of the present invention is to provide a positive electrode comprising an active material and a binder, wherein the positive electrode further comprises a binder auxiliary agent, the binder auxiliary agent comprises an emulsion polymerization functional polymer, the emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, and the positive electrode has a carbon uniformity coefficient of 12 to 30, thereby exhibiting excellent physical properties and simultaneously improving the capacity and lifespan characteristics of the battery and being capable of being manufactured by a dry process.

[0014] Another objective of the present invention is to provide a method for manufacturing the anode.

[0015] Another objective of the present invention is to provide a secondary battery comprising the anode.

[0016] A first aspect of the present invention provides an anode comprising an active material and a binder, wherein the anode further comprises a binder auxiliary agent, the binder auxiliary agent comprises an emulsion polymerization functional polymer, the emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, and the anode has a carbon uniformity factor of 12 to 30.

[0017] In one embodiment of the present invention, the porosity of the anode is 20% to 30%.

[0018] In one embodiment of the present invention, the content of the binder auxiliary agent is 10 to 150 parts by weight based on 100 parts by weight of the binder.

[0019] In one embodiment of the present invention, the content of the binder and binder aid is 0.1% to 10% by weight based on the total weight of the anode.

[0020] In one embodiment of the present invention, the emulsion polymerization functional polymer comprises a repeating unit selected from the group consisting of acrylate-based repeating units, styrene-based repeating units, and combinations thereof.

[0021] In one embodiment of the present invention, the emulsion polymerization functional polymer comprises a repeating unit selected from the group consisting of acrylate-based repeating units, styrene-based repeating units, and combinations thereof, and the content of the repeating unit selected from the group consisting of acrylate-based repeating units, styrene-based repeating units, and combinations thereof in the emulsion polymerization functional polymer is 10 mol% to 100 mol% based on the total repeating units in the emulsion polymerization functional polymer.

[0022] In one embodiment of the present invention, the binder comprises being selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP), polyvinylidene fluoride-tetrafluoroethylene (PVdF-TFE), and combinations thereof.

[0023] In one embodiment of the present invention, the active material comprises a lithium transition metal oxide.

[0024] In one embodiment of the present invention, the active material comprises a lithium transition metal oxide, and the lithium transition metal oxide is represented by the following [Chemical Formula 1].

[0025] [Chemical Formula 1]

[0026] Li a Ni b Co c M 1 d M 2 e O2

[0027] In the above chemical formula 1, M 1 is selected from the group consisting of Mn, Al, and combinations thereof, and M 2 is selected from the group consisting of Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, Y, Al, Co and combinations thereof, and a, b, c, d and e are each such that a is 0.8≤a≤1.2, b is 0.6≤b<1, c is 0≤c≤0.2, d is 0≤d≤0.3, e is 0≤e≤0.1, and b+c+d+e=1.

[0028] In one embodiment of the present invention, the positive electrode is for a secondary battery, and the secondary battery includes a liquid electrolyte.

[0029] In one embodiment of the present invention, the anode is a dry electrode.

[0030] A second aspect of the present invention provides a method for manufacturing an anode, wherein the anode comprises an active material and a binder, the anode further comprises a binder auxiliary agent, the binder auxiliary agent comprises an emulsion polymerization functional polymer, the emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, the anode has a carbon uniformity coefficient of 12 to 30, and the method comprises the step of mixing an active material raw material, a binder raw material, and a binder auxiliary agent raw material to prepare a composition for the anode.

[0031] In one embodiment of the present invention, the average particle size (D) of the binder auxiliary material 50 ) is 50 nm to 3000 nm.

[0032] A third aspect of the present invention provides a secondary battery comprising a positive electrode, wherein the positive electrode comprises an active material and a binder, and the positive electrode further comprises a binder auxiliary agent, wherein the binder auxiliary agent comprises an emulsion polymerization functional polymer, and the emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, and the positive electrode has a carbon uniformity factor of 12 to 30.

[0033] A positive electrode according to one embodiment of the present invention comprises an active material and a binder, wherein the positive electrode further comprises a binder auxiliary agent, wherein the binder auxiliary agent comprises an emulsion polymerization functional polymer, wherein the emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, and the positive electrode has a carbon uniformity coefficient of 12 to 30, thereby having excellent physical properties such as tensile strength and the ability to be manufactured by a dry process. When applied to a battery, these characteristics can improve the performance of the battery, such as increasing capacity and lifespan characteristics.

[0034] [Fig. 1] is an image showing the SEM-EDS analysis results of the positive electrode active material according to Example 3 of the present invention.

[0035] The present invention will be described in more detail below.

[0036] Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention. Accordingly, the configurations described in the embodiments described in this specification are merely one preferred embodiment of the invention and do not represent all of the technical spirit of the invention; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0037] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0038] In this specification, the term "polymer" includes both polymers composed of homogeneous repeating units and copolymers containing multiple different repeating units.

[0039] In this specification, "%" means weight percent unless otherwise explicitly indicated.

[0040] Where measurement conditions and methods are not specifically described for the physical properties described in this specification, said physical properties are measured according to measurement conditions and methods generally used by a person skilled in the art.

[0041]

[0042] The present invention will be described in detail below.

[0043]

[0044] anode

[0045] The present invention provides an anode.

[0046] In one embodiment of the present invention, the anode comprises an active material and a binder.

[0047] In one embodiment of the present invention, the anode further comprises a binder aid.

[0048] Hereinafter, each part of the anode according to one embodiment of the present invention will be described in detail.

[0049]

[0050] (1) Active substance

[0051] In one embodiment of the present invention, the content of the active material is 80% to 99% by weight based on the total weight of the anode. Specifically, the content of the active material may be 80% or more by weight, 85% or more by weight, 90% or more by weight, 91% or more by weight, 92% or more by weight, 93% or more by weight, 94% or more by weight, 95% or more by weight, or 96% or more by weight, 99% or less by weight, 98% or less by weight, or 97% or less by weight, or 80% to 99% by weight, 85% to 99% by weight, or 90% to 98% by weight. When the content of the active material satisfies the above range, the energy density of the anode can be improved to enhance battery performance, while also exhibiting properties that enable free-standing.

[0052] The above active material is not particularly limited as long as it is generally known in the relevant technical field to facilitate ion insertion and extraction within the cathode to provide a capacity and voltage suitable for the battery, exhibit a capacity and lifespan suitable for the battery, and be capable of operating under normal voltage. For example, the above active material may include lithium transition metal oxides containing transition metals such as nickel, cobalt, and manganese, lithium iron phosphate compounds, etc., but is not limited thereto.

[0053] In one embodiment of the present invention, the active material comprises a lithium transition metal oxide.

[0054] When the above lithium transition metal oxide is included in the active material, high capacity and lifespan characteristics can be expected. In addition, when the above graphite-based active material is included in the active material, high energy density and lifespan characteristics can be expected, and excellent stability can be exhibited under conditions such as long-term operation and high voltage.

[0055] In one embodiment of the present invention, the lithium transition metal oxide comprises nickel.

[0056] In one embodiment of the present invention, the lithium transition metal oxide comprises nickel and further comprises a material selected from the group consisting of cobalt, manganese, aluminum, and combinations thereof.

[0057] In one embodiment of the present invention, the lithium transition metal oxide comprises nickel and cobalt, and further comprises one selected from the group consisting of manganese, aluminum, and combinations thereof.

[0058] In one embodiment of the present invention, the lithium transition metal oxide comprises nickel, cobalt, manganese, and aluminum.

[0059] In one embodiment of the present invention, the lithium transition metal oxide comprises nickel, and the nickel content is 60 mol% to 99 mol% based on the total number of moles of transition metal in the lithium transition metal oxide. Specifically, the nickel content may be 60 mol% or more, 65 mol% or more, 70 mol% or more, 75 mol% or more, 80 mol% or more, or 85 mol% or more, 99 mol% or less, 95 mol% or less, or 90 mol% or less, and may be 60 mol% to 99 mol%, 70 mol% to 99 mol%, or 80 mol% to 95 mol%. When the nickel content satisfies the above range, the battery may have excellent capacity characteristics.

[0060] In one embodiment of the present invention, the lithium transition metal oxide comprises cobalt, and the content of the cobalt is 1 mol% to 20 mol% based on the total number of moles of transition metal in the lithium transition metal oxide. Specifically, the content of the cobalt is 1 mol% or more, 2 mol% or more, 3 mol% or more, or 4 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 9 mol% or less, 8 mol% or less, 7 mol% or less, 6 mol% or less, or 5 mol% or less, and may be 1 mol% to 20 mol%, 1 mol% to 15 mol%, or 2 mol% to 10 mol%. When the content of the cobalt satisfies the above range, it may have capacity characteristics suitable for battery application and facilitate operation at high voltage.

[0061] In one embodiment of the present invention, the lithium transition metal oxide comprises manganese, and the content of the manganese is 1 mol% to 20 mol% based on the total number of moles of transition metal in the lithium transition metal oxide. Specifically, the content of the manganese is 1 mol% or more, 2 mol% or more, 3 mol% or more, or 4 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 9 mol% or less, 8 mol% or less, 7 mol% or less, 6 mol% or less, or 5 mol% or less, and may be 1 mol% to 20 mol%, 1 mol% to 15 mol%, or 2 mol% to 10 mol%. When the content of the manganese satisfies the above range, it may have capacity characteristics suitable for battery application.

[0062] In one embodiment of the present invention, the lithium transition metal oxide comprises aluminum, and the content of the aluminum is 1 mol% to 20 mol% based on the total number of moles of transition metal in the lithium transition metal oxide. Specifically, the content of the aluminum is 1 mol% or more, 2 mol% or more, 3 mol% or more, or 4 mol% or more, 20 mol% or less, 15 mol% or less, 10 mol% or less, 9 mol% or less, 8 mol% or less, 7 mol% or less, 6 mol% or less, or 5 mol% or less, and may be 1 mol% to 20 mol%, 1 mol% to 15 mol%, or 2 mol% to 10 mol%. When the content of the aluminum satisfies the above range, it may have lifespan characteristics suitable for battery application and the stability of the battery may be improved.

[0063] The above lithium transition metal oxide may additionally include doping elements or coating elements to improve properties such as electrical conductivity or increase stability depending on the purpose of manufacturing the active material, and the doping elements or coating elements may be elements selected from the group consisting of Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, Y, Al, Co, and combinations thereof, but are not limited thereto as long as they are commonly used in the relevant technical field for manufacturing lithium transition metal oxides.

[0064] In one embodiment of the present invention, the lithium transition metal oxide is represented by the following [Chemical Formula 1].

[0065] [Chemical Formula 1]

[0066] Li a Ni b Co c M 1 d M 2 e O2

[0067] In the above chemical formula 1, M 1It is selected from the group consisting of Mn, Al, and combinations thereof.

[0068] In one embodiment of the present invention, the M 1 It is Mn and Al.

[0069] In the above chemical formula 1, M 2 is selected from the group consisting of Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, Y, Al, Co and combinations thereof.

[0070] In the above chemical formula 1, a is 0.8 ≤ a ≤ 1.2. Specifically, a may be 0.8 ≤ a ≤ 1.2, 0.9 ≤ a ≤ 1.2, or 0.9 ≤ a ≤ 1.1.

[0071] In the above chemical formula 1, b is 0.6 ≤ b < 1. Specifically, b may be 0.6 ≤ b < 1, 0.7 ≤ b ≤ 0.99, or 0.8 ≤ b ≤ 0.95.

[0072] In the above chemical formula 1, c is 0 ≤ c ≤ 0.2. Specifically, c may be 0 ≤ c ≤ 0.2, 0.01 ≤ c ≤ 0.2, or 0.02 ≤ c ≤ 0.1.

[0073] In the above chemical formula 1, d is 0 ≤ d ≤ 0.3. Specifically, d may be 0 ≤ d ≤ 0.3, 0.01 ≤ d ≤ 0.2, or 0.05 ≤ d ≤ 0.1.

[0074] In the above chemical formula 1, e is 0 ≤ e ≤ 0.1. Specifically, e may be 0 ≤ e ≤ 0.1, 0 ≤ e ≤ 0.05, or 0 ≤ e ≤ 0.03.

[0075] In the above chemical formula 1, b+c+d+e=1.

[0076] When the above lithium transition metal oxide contains a coating element, [Chemical Formula 1] represents a lithium transition metal oxide excluding the coating element.

[0077]

[0078] (2) Binder

[0079] In one embodiment of the present invention, the binder comprises a fluorine-based polymer. The fluorine-based polymer refers to a polymer comprising fluorine in each repeating unit.

[0080] In one embodiment of the present invention, the fluorine-based polymer comprises a vinylidene fluoride-based polymer.

[0081] In one embodiment of the present invention, the fluorine-based polymer comprises being selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP), polyvinylidene fluoride-tetrafluoroethylene (PVdF-TFE), and combinations thereof.

[0082] As the above binder includes the above polymer, when manufacturing an anode containing the above binder, the material within the anode can be stably bonded and exhibit properties suitable for battery utilization.

[0083] In one embodiment of the present invention, the content of the binder is 0.1% to 10% by weight based on the total weight of the anode. Specifically, the content of the binder is 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, 0.6 wt% or more, 0.7 wt% or more, 0.8 wt% or more, 0.9 wt% or more, 1 wt% or more, 1.1 wt% or more, or 1.2 wt% or more, and 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, 1.9 wt% or less, 1.8 wt% or less, 1.7 wt% or less, 1.6 wt% or less, 1.5 wt% or less, 1.4 wt% or less, or 1.3 wt% or less, and 0.1 wt% to 10 wt%, 0.5 wt% to 5 wt%, or 0.5 It may be in the range of 1.5% by weight. When the content of the binder satisfies the above range, the materials within the anode can maintain a stable bonded state.

[0084] In one embodiment of the present invention, the content of the fluorinated polymer is 0.1% to 10% by weight based on the total weight of the anode. Specifically, the content of the fluorinated polymer is 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, 0.6 wt% or more, 0.7 wt% or more, 0.8 wt% or more, 0.9 wt% or more, 1 wt% or more, 1.1 wt% or more, or 1.2 wt% or more, and 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, 1.9 wt% or less, 1.8 wt% or less, 1.7 wt% or less, 1.6 wt% or less, 1.5 wt% or less, 1.4 wt% or less, or 1.3 wt% or less, and 0.1 wt% to 10 wt%, 0.5 wt% to 5 wt%, or 0.5 It may be in the range of 1.5% by weight. When the content of the fluorinated polymer satisfies the above range, it is possible to manufacture an environmentally friendly anode while maintaining a stable bonded state of the materials within the anode.

[0085]

[0086] (3) Binder aid

[0087] In one embodiment of the present invention, the binder auxiliary agent comprises an emulsion polymerization functional polymer. The term "emulsion polymerization functional polymer" refers to a polymer in which some or all of the monomers included in the polymer are capable of emulsion polymerization, and thus some or all of the polymer can be polymerized by emulsion polymerization.

[0088] By including the above-mentioned emulsion polymerizable functional polymer as a binder auxiliary, the raw material can be manufactured by emulsion polymerization; however, since manufacturing by dispersion polymerization and suspension polymerization is also possible when the raw material can be manufactured by emulsion polymerization, the polymerization method of the above-mentioned binder auxiliary is not limited to emulsion polymerization. When the raw material of the binder auxiliary is manufactured by the above-mentioned emulsion polymerization, dispersion polymerization, and suspension polymerization, it becomes easy to control the particle size of the raw material.

[0089] In one embodiment of the present invention, the term "emulsion polymerization functional polymer" refers to a polymer in which part or all of the polymer is polymerized by a polymerization method selected from the group consisting of emulsion polymerization, dispersion polymerization, and suspension polymerization.

[0090] In one embodiment of the present invention, the emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C.

[0091] Specifically, the glass transition temperature of the emulsion polymerization functional polymer may be 60°C or higher, 70°C or higher, 80°C or higher, or 90°C or higher, 200°C or lower, 190°C or lower, 180°C or lower, 170°C or lower, 160°C or lower, 150°C or lower, 140°C or lower, 130°C or lower, 120°C or lower, 110°C or lower, or 100°C or lower, and may be 60°C to 200°C, 60°C to 150°C, or 90°C to 120°C.

[0092] The above-mentioned non-fluorinated polymer refers to a polymer that does not contain fluorine.

[0093] If the above emulsion polymerization functional polymer is a non-fluorinated polymer satisfying the glass transition temperature, polymerization via emulsion polymerization is easy, and if a fluorinated polymer is used in the binder, it is possible to manufacture an eco-friendly anode by replacing a portion of the fluorinated polymer in the anode with a non-fluorinated polymer.

[0094] In one embodiment of the present invention, the binder has an average particle size (D 50It is derived from a binder auxiliary material having a thickness of 50 nm to 3000 nm. Specifically, the average particle size of the binder auxiliary material is 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, 90 nm or more, 100 nm or more, 150 nm or more, 200 nm or more, 250 nm or more, 300 nm or more, or 350 nm or more, and 3000 nm or less, 2900 nm or less, 2800 nm or less, 2700 nm or less, 2600 nm or less, 2500 nm or less, 2400 nm or less, 2300 nm or less, 2200 nm or less, 2100 nm or less, 2000 nm or less, 1900 nm or less, 1800 nm or less, 1700 nm or less, 1600 nm or less, 1500 nm or less, 1400 nm or less, 1300 nm or less, 1200 nm or less, 1100 nm The average particle size of the binder auxiliary material may be 1000 nm or less, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, 450 nm or less, or 400 nm or less, and may be 50 nm to 3000 nm, 100 nm to 2000 nm, or 200 nm to 1200 nm. When the average particle size of the binder auxiliary material satisfies the above range, uniform mixing is possible even when mixed dry with the material in the anode composition, so the distribution of the binder auxiliary in the anode can be easily controlled.

[0095] In one embodiment of the present invention, the emulsion polymerization functional polymer comprises a repeating unit selected from the group consisting of acrylate-based repeating units, styrene-based repeating units, and combinations thereof. When the emulsion polymerization functional polymer comprises a repeating unit selected from the group, it becomes easier to manufacture the polymer in the form of particles having a target particle size through emulsion polymerization, dispersion polymerization, and suspension polymerization, and accordingly, the particle size of the binder auxiliary material containing the emulsion polymerization functional polymer can be controlled within a target range.

[0096] In one embodiment of the present invention, the content of a repeating unit selected from the group consisting of acrylate-based repeating units, styrene-based repeating units, and combinations thereof in the emulsion-polymerizable functional polymer is 10 mol% to 100 mol% based on the total repeating units in the emulsion-polymerizable functional polymer. Specifically, it may be 10 mol% or more, 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, or 80 mol% or more, 100 mol% or less, 99 mol% or less, or 90 mol% or less, and may be 10 mol% to 100 mol%, 20 mol% to 100 mol%, or 80 mol% to 100 mol%. When the content of the repeating unit selected from the specific group satisfies the above range, it can contribute to the improvement of the physical properties of the anode to a level equivalent to or greater than that of a fluorine-based polymer.

[0097] In one embodiment of the present invention, the emulsion polymerizable functional polymer is polystyrene (PS), styrene-isoprene copolymer (PS-co-ISP), styrene-acrylonitrile copolymer (SAN), styrene-acrylic acid copolymer, styrene-methyl methacrylate copolymer (SMMA), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyethyl acrylate (PEA), polymethyl methacrylate (PEMA), and polybutyl acrylate (PBA). It includes those selected from the group consisting of poly(butyl methacrylate) (PBMA), poly(cyclohexyl methacrylate) (PCHMA), methyl methacrylate-acrylonitrile copolymer (MMA-AN), acrylonitrile-styrene-acrylate copolymer (ASA), and combinations thereof.

[0098] When the above-mentioned emulsion polymerization functional polymer includes one selected from the above group, not only is it easier to control the particle size of the binder auxiliary material, but the physical properties of the anode containing the binder auxiliary can also be further improved.

[0099] In one embodiment of the present invention, the content of the binder aid is 0.1% to 10% by weight based on the total weight of the anode. Specifically, the content of the binder auxiliary agent is 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, or 0.6 wt% or more, 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, 1.9 wt% or less, 1.8 wt% or less, 1.7 wt% or less, 1.6 wt% or less, 1.5 wt% or less, 1.4 wt% or less, 1.3 wt% or less, 1.2 wt% or less, 1.1 wt% or less, 1 wt% or less, 0.9 wt% or less, 0.8 wt% or less, or 0.7 wt% or less, and is 0.1 wt% to 10 wt%, 0.2 wt% to 5 wt%, or 0.5 wt%. It may be in the range of 2% by weight. When the content of the binder auxiliary agent satisfies the above range, dry manufacturing of the anode becomes easier and suitable physical properties for battery utilization can be exhibited.

[0100] In one embodiment of the present invention, the content of the emulsion polymerization functional polymer is 0.1% to 10% by weight based on the total weight of the anode. Specifically, the content of the emulsion polymerizable functional polymer is 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, or 0.6 wt% or more, 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, 1.9 wt% or less, 1.8 wt% or less, 1.7 wt% or less, 1.6 wt% or less, 1.5 wt% or less, 1.4 wt% or less, 1.3 wt% or less, 1.2 wt% or less, 1.1 wt% or less, 1 wt% or less, 0.9 wt% or less, 0.8 wt% or less, or 0.7 wt% or less, and is 0.1 wt% to 10 wt%, 0.2 wt% to 5 wt% or It may be 0.5% by weight to 2% by weight. When the content of the emulsion polymerization functional polymer satisfies the above range, dry manufacturing of the anode becomes easier, and it becomes possible to manufacture an eco-friendly anode by including a non-fluorine polymer as a binder auxiliary agent in the anode at a certain level or higher.

[0101] In one embodiment of the present invention, the content of the binder and binder aid is 0.1 weight% to 10 weight%. Specifically, the content of the binder and binder aid is 0.1 wt% or more, 0.5 wt% or more, 1 wt% or more, 1.1 wt% or more, 1.2 wt% or more, 1.3 wt% or more, 1.4 wt% or more, 1.5 wt% or more, 1.6 wt% or more, 1.7 wt% or more, 1.8 wt% or more, 1.9 wt% or more, 2 wt% or more, or 2.1 wt% or more, and 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, 2.5 wt% or less, 2.4 wt% or less, 2.3 wt% or less, or 2.2 wt% or less, and can be 0.1 wt% to 10 wt%, 0.5 wt% to 5 wt%, or 1.5 wt% to 2.5 wt%. there is.

[0102] The content of the binder and binder auxiliary agent mentioned above refers to the sum of the binder content and the binder auxiliary agent content.

[0103] In one embodiment of the present invention, the content of the binder auxiliary agent is 10 to 150 parts by weight based on 100 parts by weight of the binder. Specifically, the content of the binder auxiliary agent is 10 parts by weight or more, 20 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, or 50 parts by weight or more based on 100 parts by weight of the binder, and 150 parts by weight or less, 140 parts by weight or less, 130 parts by weight or less, 120 parts by weight or less, 110 parts by weight or less, 100 parts by weight or less, 90 parts by weight or less, 80 parts by weight or less, 70 parts by weight or less, or 60 parts by weight or less, and may be 10 to 150 parts by weight, 20 to 100 parts by weight, or 40 to 80 parts by weight.

[0104] In one embodiment of the present invention, the content of the emulsion polymerization functional polymer is 10 to 150 parts by weight based on 100 parts by weight of binder. Specifically, the content of the emulsion polymerization functional polymer is 10 parts by weight or more, 20 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, or 50 parts by weight or more based on 100 parts by weight of binder, and 150 parts by weight or less, 140 parts by weight or less, 130 parts by weight or less, 120 parts by weight or less, 110 parts by weight or less, 100 parts by weight or less, 90 parts by weight or less, 80 parts by weight or less, 70 parts by weight or less, or 60 parts by weight or less, and may be 10 to 150 parts by weight, 20 to 100 parts by weight, or 40 to 80 parts by weight.

[0105] When the content of the above binder auxiliary agent and the emulsion polymerization functional polymer satisfies the above range, it is possible to manufacture a freestanding anode even with a dry process and to manufacture an eco-friendly anode.

[0106]

[0107] (4) bipolar

[0108] In one embodiment of the present invention, the anode has a carbon uniformity coefficient of 12 to 30. Specifically, the carbon uniformity coefficient is 12 or more, 12.5 or more, 13 or more, 13.5 or more, 14 or more, 14.5 or more, 15 or more, 15.5 or more, 16 or more, 16.5 or more, 17 or more, 17.5 or more, 18 or more, 19.5 or more, 20 or more, 20.5 or more, 21 or more, 21.5 or more, 22 or more, 22.5 or more, 23 or more, 23.5 or more, 30 or less, 29.5 or less, 29 or less, 28.5 or less, 28 or less, 27.5 or less, 27 or less, 26.5 or less, 26 or less, 25.5 or less, 25 or less, 24.5 or less, or 24 or less, and may be 12 to 30, 15 to 29, or 17 to 25.

[0109] The above carbon uniformity coefficient is a value related to the degree of distribution of the binder within the anode and can be expressed by Equation 1 as follows.

[0110] [Equation 1]

[0111] Carbon uniformity factor = ( Standard deviation / Mean ) × 100

[0112] The above mean and standard deviation relate to the mass ratio of carbon elements to the total sum of carbon and oxygen elements within the anode, measured multiple times or more for the same anode. When the carbon uniformity coefficient within the anode satisfies the above range, the binder within the anode is appropriately distributed, exhibiting physical properties suitable for battery utilization while also demonstrating a distribution sufficient to form stable adhesion between the anode active material layer and the current collector. Accordingly, not only can the physical properties of the anode be improved, but the performance and stability of the battery containing the anode can also be enhanced.

[0113] The mass ratio of such carbon elements can be measured using methods commonly used in the relevant technical field to confirm the distribution or content of specific elements, particularly carbon and oxygen, within a substance. Specifically, the mass ratio of carbon elements can be measured using, but is not limited to, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) or scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), which capture an image of a substance and detect the distribution of elements within that image.

[0114] In one embodiment of the present invention, the mass ratio of the carbon element is measured using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS).

[0115] In one embodiment of the present invention, the positive electrode is for a secondary battery. When the secondary battery includes the positive electrode, the secondary battery has excellent physical properties and battery performance such as capacity and lifespan characteristics can be improved.

[0116] In one embodiment of the present invention, the secondary battery comprises a liquid electrolyte.

[0117] In one embodiment of the present invention, the porosity of the anode is 20% to 30%. Specifically, the porosity may be 20% or more, 21% or more, 22% or more, 23% or more, 24% or more, or 25% or more, 30% or less, 29% or less, 28% or less, 27% or less, or 26% or less, and may be 20% to 30%, 22% to 28%, or 24% to 26%. When the porosity of the anode satisfies the above range, it is easy to apply to a battery using a liquid electrolyte.

[0118] In one embodiment of the present invention, the anode further comprises a conductive material.

[0119] The above conductive material is intended to impart conductivity to the anode, and means that a material having electronic conductivity can be included in the anode without causing a chemical change of the material when operating a battery or the like containing the above anode. Examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fibers; metal powder or metal fibers such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used, but is not limited thereto as long as it is generally used in the relevant technical field.

[0120] In one embodiment of the present invention, the conductive material comprises carbon nanotubes.

[0121] In one embodiment of the present invention, the conductive material comprises multi-walled carbon nanotubes.

[0122] In one embodiment of the present invention, the content of the conductive material is 0.1 wt% to 10 wt% based on the total weight of the anode. Specifically, the content of the conductive material is 0.1 wt% or more, 0.5 wt% or more, 1 wt% or more, 1.1 wt% or more, 1.2 wt% or more, 1.3 wt% or more, 1.4 wt% or more, 1.5 wt% or more, 1.6 wt% or more, 1.7 wt% or more, 1.8 wt% or more, or 1.9 wt% or more, 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, or 2 wt% or less, and may be 0.1 wt% to 10 wt%, 0.5 wt% to 5 wt%, or 1 wt% to 3 wt%.

[0123] When the content of the above conductive material satisfies the above range, the above anode can exhibit electrical conductivity suitable for application to a battery.

[0124] In one embodiment of the present invention, the anode is a dry electrode.

[0125] The above dry electrode refers to an electrode manufactured using a dry method, specifically meaning that the mixing of materials contained within the electrode is performed without a separate solvent.

[0126] In one embodiment of the present invention, the anode further comprises, in addition to the active material, binder, binder aid, and conductive material described above, additives such as a filler, coating agent, dispersant, and ion conductivity aid. Known materials generally used in the anodes of all-solid-state secondary batteries may be used as the filler, coating agent, dispersant, ion conductivity aid, etc.

[0127] In one embodiment of the present invention, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector. In this case, the positive electrode active material layer comprises the active material, a binder, etc.

[0128] The above positive current collector may include a highly conductive metal, and is not particularly limited as long as it facilitates the adhesion of the positive active material layer and is non-reactive within the voltage range of the battery. The above positive current collector may be, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. Additionally, the above positive current collector may typically have a thickness of 3 μm to 500 μm, and may form fine irregularities on the surface of the current collector to increase the adhesion of the positive active material. It may be used in various forms, such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.

[0129] In one embodiment of the present invention, the thickness of the anode is 70 μm to 150 μm.

[0130]

[0131] Method for manufacturing an anode

[0132] The present invention provides a method for manufacturing an anode.

[0133] In one embodiment of the present invention, the anode comprises an active material and a binder, and the anode further comprises a binder auxiliary agent, wherein the binder auxiliary agent comprises an emulsion polymerization functional polymer, and the emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, and the anode has a carbon uniformity coefficient of 12 to 30.

[0134] In one embodiment of the present invention, the manufacturing method is the manufacturing method of the anode described above.

[0135] In one embodiment of the present invention, the manufacturing method comprises the step of preparing an anode composition by mixing an active material raw material, a binder raw material, and a binder auxiliary raw material.

[0136] The above-mentioned active material raw material refers to a substance that serves as a raw material for the active material included in the cathode, meaning the material prior to undergoing a process for manufacturing the cathode from the cathode composition, such as mixing each raw material within the cathode composition. Therefore, unless special modification treatment is performed on the raw material included in the composition during the cathode manufacturing process, the main component of the active material raw material is nearly identical to the main component of the active material.

[0137] The active material of the anode according to one embodiment of the present invention is substantially the same as the active material raw material. The term "substantially the same" means that while the physical form of the precursor may change, there is no change in the main chemical components.

[0138] In one embodiment of the present invention, the active material raw material is the same as the active material.

[0139] In one embodiment of the present invention, the content of the active material raw material in the anode composition is the same as the content of the active material in the anode.

[0140] The above-mentioned binder raw material refers to a substance that serves as a raw material for the binder included in the anode, meaning the material prior to undergoing a process of manufacturing the anode from the anode composition, such as mixing the individual raw materials within the anode composition. Therefore, unless special modification treatments are performed on the raw materials included in the composition during the anode manufacturing process, the main component of the binder raw material is nearly identical to the main component of the binder.

[0141] The binder of the anode according to one embodiment of the present invention is substantially identical to the binder raw material. The term "substantially identical" means that there is no change in the physical form of the raw material or its major chemical components.

[0142] In one embodiment of the present invention, the binder raw material is the same as the binder.

[0143] In one embodiment of the present invention, the content of the binder raw material in the anode composition is the same as the content of the binder in the anode.

[0144] The above-mentioned binder auxiliary agent refers to a composition that assists in, or even replaces, the role of a binder in enabling the free-standing of the anode by stably forming the binding of each material within the anode.

[0145] The above-mentioned binder auxiliary raw material refers to a substance that serves as the raw material for the binder auxiliary included in the anode, meaning the material prior to undergoing a process of manufacturing the anode from the anode composition, such as mixing each raw material within the anode composition. Therefore, unless special modification treatment is performed on the raw material included in the composition during the anode manufacturing process, the main component of the binder auxiliary raw material is nearly identical to the main component of the binder auxiliary.

[0146] The binder auxiliary of the anode according to one embodiment of the present invention is substantially the same as the binder auxiliary raw material. The term "substantially the same" means that while the physical form of the raw material may change, there is no change in the main chemical components.

[0147] In one embodiment of the present invention, the content of the binder auxiliary material in the anode composition is the same as the content of the binder auxiliary in the anode.

[0148] The above mixing is not particularly limited as long as it is a method commonly used in the relevant technical field. The purpose of the above mixing is to uniformly disperse various raw materials, and it may be carried out using milling processes such as ball milling or jet milling, or mixing methods utilizing shear force.

[0149] In one embodiment of the present invention, the mixing of the active material raw material, the binder raw material, and the binder auxiliary raw material is a dry mixing.

[0150] In one embodiment of the present invention, the anode composition further comprises a conductive material raw material. In one embodiment of the present invention, the conductive material raw material is the same as the conductive material.

[0151] In one embodiment of the present invention, the content of the conductive material raw material in the anode composition is the same as the content of the conductive material in the anode.

[0152] The above active material raw material, binder raw material, binder auxiliary raw material, and conductive material raw material are the same as those described above, so a detailed explanation thereof is omitted.

[0153] In one embodiment of the present invention, the anode is manufactured by laminating an anode active material layer, prepared by dry mixing, onto an anode current collector.

[0154]

[0155] secondary battery

[0156] The present invention also provides a secondary battery.

[0157] In one embodiment of the present invention, the secondary battery is a secondary battery comprising a positive electrode, wherein the positive electrode comprises an active material and a binder, and the positive electrode further comprises a binder auxiliary agent, wherein the binder auxiliary agent comprises an emulsion polymerization functional polymer, and the emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, and the positive electrode has a carbon uniformity coefficient of 12 to 30.

[0158] In one embodiment of the present invention, the secondary battery includes the positive electrode described above.

[0159] In one embodiment of the present invention, the secondary battery comprises a negative electrode and a positive electrode.

[0160] The above cathode may include a cathode current collector and a cathode active material layer located on the cathode current collector.

[0161] In one embodiment of the present invention, the negative electrode active material layer may optionally include a binder and a conductive material together with the negative electrode active material.

[0162] The above-mentioned negative current collector is not particularly limited as long as it possesses high conductivity without causing chemical changes in the battery. The above-mentioned negative current collector may be, for example, copper, stainless steel, aluminum, nickel, titanium, or calcined carbon, and may be a copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., or an aluminum-cadmium alloy. In addition, the above-mentioned negative current collector may typically have a thickness of 3 μm to 500 μm, and may increase the adhesion of the negative active material by forming fine irregularities on the surface of the current collector. The above-mentioned negative current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0163] As the above-mentioned cathode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO₂ β Examples include metal oxides capable of doping and dedoping lithium, such as (0 < β < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the metal compound and carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the negative electrode active material. Furthermore, the carbon material may include low-crystallinity carbon and high-crystallinity carbon. Representative examples of the above low-crystallinity carbon include soft carbon and hard carbon, and representative examples of the above high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes. The above negative electrode active material may be included in the negative electrode active material layer in an amount of 80% to 99% by weight based on the total weight of the negative electrode active material layer.

[0164] In one embodiment of the present invention, the binder of the negative electrode active material layer is a component that assists in the bonding between the conductive material, the active material, and the current collector, and can typically be added to the negative electrode active material layer in an amount of 0.1% to 10% by weight based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0165] In one embodiment of the present invention, the conductive material of the negative electrode active material layer may be added to the negative electrode active material layer in an amount of 10% by weight or less, preferably 5% by weight or less, based on the total weight of the negative electrode active material layer, as a component for further improving the conductivity of the negative electrode active material. Such a conductive material is not particularly limited as long as it possesses conductivity without causing chemical changes in the battery. For example, the conductive material may be graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon; metal powders such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives.

[0166]

[0167] In one embodiment of the present invention, the secondary battery comprises a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. Additionally, the lithium secondary battery may optionally further comprise a battery container housing an electrode assembly of the positive electrode, negative electrode, and separator described above, and a sealing member for sealing the battery container.

[0168] The above separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions; it may be used without special restrictions as long as it is commonly used as a separator in a lithium secondary battery. In particular, using a separator that exhibits low resistance to the movement of electrolyte ions and has excellent electrolyte wettability can improve the performance of the battery. For example, porous polymer films made of polyolefin-based polymers such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or porous polymer films such as laminated structures of two or more layers thereof, may be used. In addition, conventional porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, to ensure heat resistance or mechanical strength, a coated separator containing ceramic components or polymer materials may be used, and it may optionally be used in a single-layer or multi-layer structure, but is not limited thereto as long as it is generally known in the relevant technical field.

[0169] The above electrolyte may be used without special restrictions as long as it allows for the smooth movement of lithium ions. Examples include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., but are not limited to those generally known in the relevant technical field.

[0170] In one embodiment of the present invention, the electrolyte is a liquid electrolyte.

[0171] In one embodiment of the present invention, the electrolyte is a liquid electrolyte comprising an organic solvent.

[0172] The above organic solvent may be used without special restrictions as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. For example, ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; aromatic hydrocarbon-based solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, a directional ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used, but are not limited thereto as long as they are commonly used in the relevant technical field. Among these, for the charge / discharge performance of the battery, a mixture of a carbonate-based solvent, specifically a cyclic carbonate having high ionic conductivity and high dielectric constant (e.g., ethylene carbonate or propylene carbonate, etc.) and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) may be used.

[0173] A lithium salt can be used with an organic solvent to improve the ionic conductivity of the above electrolyte.

[0174] The above lithium salt may be used without special restrictions as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. For example, as an anion of the above lithium salt, F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - The lithium salt may be at least one selected from the group consisting of LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, but is not limited thereto as long as it is generally known in the relevant technical field.

[0175] The concentration of the lithium salt can be appropriately adjusted by a person skilled in the art according to the purpose, and may be included within a range of 0.1 M to 2.0 M based on the electrolyte, considering battery performance and economic feasibility. When the concentration of the lithium salt satisfies the above range, the electrolyte has appropriate conductivity and viscosity, so excellent electrolyte performance can be exhibited and lithium ions can move effectively.

[0176] In addition to the above electrolyte components, the above electrolyte may further include one or more additives for the purpose of improving the lifespan characteristics of the battery, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery, such as, for example, haloalkylene carbonate-based compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, triamide hexaphosphate, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride. In this case, the above additive may be included in the electrolyte in an amount of 0.1% to 5% by weight relative to the total weight of the electrolyte.

[0177]

[0178] A secondary battery comprising a positive electrode according to one embodiment of the present invention is useful in fields such as portable devices like mobile phones, laptop computers, and digital cameras, and electric vehicles like hybrid electric vehicles (HEVs) and electric vehicles (EVs), because it stably exhibits excellent capacity characteristics, output characteristics, and lifespan characteristics.

[0179] There are no specific restrictions on the external shape of the above secondary battery, but it may be a cylindrical type using a can, a prismatic type, a pouch type, or a coin type.

[0180] A secondary battery according to one embodiment of the present invention can be used not only as a battery cell used as a power source for a small device, but can also preferably be used as a unit cell in a medium-to-large battery module comprising a plurality of battery cells.

[0181] Accordingly, in one embodiment of the present invention, a battery module including the secondary battery as a unit cell and a battery pack including the same are provided.

[0182] The above battery module or battery pack can be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0183] Specific embodiments of the present invention are presented below. However, the embodiments described below are merely for the purpose of specifically illustrating or explaining the present invention and do not limit the present invention. Furthermore, details not described herein can be sufficiently technically inferred by a person skilled in the art, so their description is omitted.

[0184]

[0185] Examples

[0186]

[0187] <Example 1>

[0188] (1) Preparation of emulsion polymerization functional polymer

[0189] To prepare the polymerization solution, 25 mg of SDS (Sodium Dodecyl Sulfate; manufactured by Sigma Aldrich) was added to 450 g of water and mixed while raising the temperature to 70°C.

[0190] While maintaining the temperature of the polymerization solution prepared above, a total of 45 g of methyl methacrylate (manufactured by Daejeong Chemical Co., Ltd., purity 99%) was added to the solution as a monomer and stirred at 1200 rpm for 1 hour, then 0.25 g of potassium persulfate was added and polymerization was carried out for 18 hours while maintaining the stirring speed and temperature.

[0191] Subsequently, 30 g of the polymerization solution was centrifuged at 12,000 rpm, and the supernatant was removed. To remove impurities from the solution from which the supernatant had been removed, 30 g of ethyl alcohol was added and uniformly dispersed using an ultrasonic cleaner, after which centrifugation was performed at 12,000 rpm for 20 minutes. After performing the impurity removal process a total of three times, the polymer particles from which the supernatant had been removed were dried using a convection oven at 60°C for at least 6 hours.

[0192] After drying above, D 50 This 360 nm emulsion polymerization functional polymer polymethyl methacrylate was obtained.

[0193] (2) Manufacturing of film

[0194] LiNi as an active material 0.88 Co 0.05 Mn 0.05 Al 0.02 96 wt% of an active material (HN803L, manufactured by LG Chem) having a composition indicated by O2, 1.4 wt% of binder polytetrafluoroethylene (F-106, manufactured by DAIKIN) as a binder, 0.7 wt% of an emulsion polymerization functional polymer prepared by the above method as a binder auxiliary agent, and 1.9 wt% of multi-walled carbon nanotubes (BT-1001M, manufactured by LG Chem) as a conductive material were introduced into a mixing device (RM-200C, manufactured by Hapro) and mixed at 170°C and 30 rpm for 5 minutes. Subsequently, the mixture was introduced into a laboratory blender and ground at 10,000 rpm for 10 seconds to obtain a powder for manufacturing an anode.

[0195] The above anode manufacturing powder was fed into a wrap calender (roll diameter: 80 mm, roll temperature: 80℃) to manufacture a free-standing film.

[0196] (3) Preparation of the anode

[0197] Subsequently, the above film was fed into a room temperature rolling mill at a speed of 1 rpm and laminated onto a current collector, a 20 nm thick aluminum foil (Dongwon Systems, CLF), to manufacture an anode.

[0198]

[0199] <Example 2>

[0200] Using cyclohexyl methacrylate (manufactured by Daejeong Chemical Co., Ltd., 99% purity) as the above monomer, D as the above emulsion polymerization functional polymer 50 Except for preparing a polycyclohexyl methacrylate with a thickness of 220 nm, it was prepared using the same method as in Example 1.

[0201]

[0202] <Example 3>

[0203] Using styrene (manufactured by Daejeong Chemical Co., Ltd., 99% purity) as the above monomer, D as the above emulsion polymerization functional polymer 50 Except for manufacturing this 350 nm polystyrene, it was manufactured using the same method as in Example 1.

[0204]

[0205] <Example 4>

[0206] Styrene (manufactured by Daejeong Chemical Co., Ltd., 99% purity) and isoprene (manufactured by Sigma Aldrich, I19551) were used as the monomers in an 8:2 molar ratio and polymerized in a pressure flask to produce the above emulsion polymerizable functional polymer D 50 Except for preparing a 210 nm polystyrene-isoprene copolymer, it was prepared using the same method as in Example 1.

[0207]

[0208] <Example 5>

[0209] Styrene (manufactured by Daejeong Chemical Co., Ltd., 99% purity) and isoprene (manufactured by Sigma Aldrich, I19551) were used as the monomers in a molar ratio of 9:1, and polymerized in a pressure flask without using SDS to obtain the above emulsion polymerizable functional polymer D 50 Except for preparing a 570 nm polystyrene-isoprene copolymer, it was prepared using the same method as in Example 1.

[0210]

[0211] <Example 6>

[0212] Styrene (manufactured by Daejeong Chemical Co., Ltd., 99% purity) and isoprene (manufactured by Sigma Aldrich, I19551) were used as the monomers in a molar ratio of 9:1, 2.5 g of potassium persulfate was used without using SDS, and polymerization was carried out in a pressure flask to produce the above-mentioned emulsion polymerizable functional polymer D 50 Except for preparing a polystyrene-isoprene copolymer with a thickness of 1050 nm, it was prepared using the same method as in Example 1.

[0213]

[0214] <Example 7>

[0215] D as the above emulsion polymerization functional polymer using styrene (manufactured by Daejeong Chemical Co., Ltd., 99% purity) and acrylonitrile (manufactured by TCI, A0146) in a molar ratio of 2:8. 50 Except for preparing a styrene-acrylonitrile copolymer with a thickness of 260 nm, it was prepared using the same method as in Example 1.

[0216]

[0217] <Example 8>

[0218] Styrene (manufactured by Daejeong Chemical Co., Ltd., 99% purity) was used as the monomer, and potassium persulfate was added to the polymerization solution. Polymerization was then carried out for 40 minutes while maintaining the stirring speed and temperature. Subsequently, 200 g of ethyl alcohol was added to the polymerization solution upon completion of polymerization. The polymerization solution containing ethyl alcohol was then centrifuged in 30 g portions at 12,000 rpm, and the supernatant was removed. Accordingly, D was finally obtained as the above-mentioned emulsion-polymerizable functional polymer. 50 Except for manufacturing 120 nm polystyrene, it was manufactured using the same method as in Example 1.

[0219]

[0220] <Example 9>

[0221] Styrene (manufactured by Daejeong Chemical Co., Ltd., 99% purity) was used as the monomer, and potassium persulfate was added to the polymerization solution. Polymerization was then carried out for 15 minutes while maintaining the stirring speed and temperature. Subsequently, 200 g of ethyl alcohol was added to the polymerization solution upon completion of polymerization. The polymerization solution containing ethyl alcohol was centrifuged in 30 g portions at 12,000 rpm, and the supernatant was removed. Accordingly, D was finally obtained as the above-mentioned emulsion-polymerizable functional polymer. 50 Except for manufacturing 60 nm polystyrene, it was manufactured using the same method as in Example 1.

[0222]

[0223] <Reference Example 1>

[0224] In the same manner as the prior art, the above binder was added at 2.1 wt% and an emulsion polymerization functional polymer was not used, except that it was prepared in the same way as Example 1.

[0225]

[0226] <Reference Example 2>

[0227] It was prepared in the same manner as Example 1, except that the above-mentioned emulsion polymerization functional polymer was not used, just like the prior art.

[0228]

[0229] <Comparative Example 1>

[0230] The above active material, binder, and conductive material were added to a xylene solvent and mixed to prepare a slurry for manufacturing an anode, and the slurry was loaded onto a current collector and dried in a convection oven at 130°C for 10 minutes to manufacture an anode, except that the anode was manufactured using the same method as in Example 1.

[0231]

[0232] <Comparative Example 2>

[0233] Styrene (manufactured by Daejeong Chemical Co., Ltd., 99% purity) and butadiene (manufactured by Sigma Aldrich, 295035) were used as the monomers in a molar ratio of 9:1, and 0.25 g of SDS was used. A butadiene rubber emulsion was prepared by polymerizing in a pressure flask, and after drying the emulsion, it was fed into a laboratory blender and ground at 10,000 rpm for 30 seconds to produce D as the binder auxiliary. 50 Except for manufacturing this 80 nm styrene butadiene rubber, it was manufactured using the same method as in Example 1.

[0234]

[0235] <Comparative Example 3>

[0236] After drying the nitrile butadiene emulsion (LG Chem, NL 205) with the above monomer, it is fed into a laboratory blender and ground at 10,000 rpm for 30 seconds to produce D as the above binder aid 50 Except for manufacturing a nitrile butadiene rubber with a thickness of 280 nm, it was manufactured using the same method as in Example 1.

[0237]

[0238] <Comparative Example 4>

[0239] Styrene (manufactured by Daejeong Chemical Co., Ltd., 99% purity) and isoprene (manufactured by Sigma Aldrich, I19551) were used as the monomers in a molar ratio of 9:1, ethanol was used instead of water as the solvent, SDS was not used, and 0.2 g of azobisisobutyronitrile was used instead of potassium persulfate, and polymerization was carried out in a pressure flask to produce the above-mentioned emulsion polymerizable functional polymer D 50 Except for preparing a 3150 nm polystyrene-isoprene copolymer, it was prepared using the same method as in Example 1.

[0240]

[0241] Experimental Example

[0242]

[0243] <Experimental Example 1: Evaluation of Anode Characteristics>

[0244] (1) Evaluation of thermal properties of emulsion polymerization functional polymer

[0245] Before manufacturing the above-mentioned battery, each emulsion polymerization functional polymer was collected from the manufactured battery and the emulsion polymerization functional polymer, and the thermal properties of the emulsion polymerization functional polymer were evaluated using a Differential Scanning Calorimetry (DSC) (Mettler Toledo, DSC3+). Specifically, the evaluation of the thermal properties was performed under nitrogen gas conditions at a scan rate of 10 ℃ / min from 40℃ to 300℃.

[0246] (2) Porosity evaluation

[0247] The porosity of the above-manufactured battery was calculated using the following formula, where real density is the density of the anode containing pores, and true density is the density of the solid without pores (the solid constituting the anode). True density was measured by adding water, which is a dispersion medium, to a pycnometer cell, then placing the solid sample to be measured into it; the volume was calculated based on the height of the rising dispersion medium, and this was divided by the mass of the solid sample. In this case, the true density of the solid sample was determined by calculating the true density of each of the solid constituting the anode—namely, the active material, the conductive material, and the binder powder—and then applying the proportions included in the anode layer to obtain the true density of the mixed powder. Meanwhile, the true density of the anode layer was calculated by determining the volume based on the width, length, and thickness of the anode layer loaded onto the current collector and dividing this by the mass.

[0248] Porosity (%) = [1 - (True Density / True Density)] × 100

[0249] (3) Carbon uniformity factor analysis

[0250] To evaluate the carbon uniformity coefficient of the anodes prepared in the above examples and comparative examples, each anode rolled on a current collector was scraped off with a laser blade to obtain powder for each anode. Subsequently, the anode powder was fed into a stainless steel blade blender and ground at 10,000 rpm for 60 seconds. The ground powder was dispersed in ethanol, dropped onto a glass substrate, and dried at room temperature to remove the ethanol, thereby preparing an evaluation sample.

[0251] To measure the evaluation sample, Pt sputtering of approximately 5 nm to 10 nm was performed on the surface of the sample. Subsequently, the sample was magnified and photographed at ×2000 magnification using a Scanning Electron Microscope (SEM) (JEOL, JSM-7610F) under conditions of 15 kV, 8 mm distance, and probe current 18. Specifically, the image captured without magnification was divided into 4 rows and 5 columns at uniform intervals to distinguish a total of 20 regions. The division of these regions was performed only when there were no areas where the sample was not observed in the image captured without magnification. Subsequently, the exact center of each region was magnified and photographed at ×2000 magnification. Energy Dispersive X-ray Spectroscopy (EDS) elemental analysis was performed on the anode powder in the magnified and photographed images. The above EDS elemental analysis was performed using AZTEC software, and the peaks of the two elements, carbon and oxygen, in the graph obtained through EDS analysis within the software were integrated, and the mass ratio of carbon to the total of carbon and oxygen elements was measured. The measurement of the mass ratio as described above was performed identically for a total of 20 different regions within the same sample, and the carbon uniformity coefficient of the anode was calculated using the mean and standard deviation of the 20 mass ratios using Equation 1 below.

[0252] [Equation 1]

[0253] Carbon uniformity factor = ( Standard deviation / Mean ) × 100

[0254]

[0255] The characteristics of the anode evaluated by the above method are shown in [Table 1] below.

[0256]

[0257] Glass Transition Temperature (°C) Porosity (%) Carbon Homogeneity Coefficient Preparation After Preparation Example 1 111110 25 23.5 Example 2 10 410 425 17.9 Example 3 113 113 25 28.2 Example 4 9 49 425 22.9 Example 5 9 19 0 24 21.7 Example 6 8 9 89 25 23.8 Example 7 119 119 26 24.9 Example 8 111 11125 18.7 Example 9 110 110 26 13.5 Reference Example 1 n / an / a 24 15.6 Reference Example 2 n / an / a 24 14.8 Comparative Example 1 9 19 125 6 0.5 Comparative Example 2 0 or less 0 or less 26 33.1 Comparative Example 3 0 or less 0 Below 2542.9 Comparative Example 488862562.1

[0258]

[0259] As shown in [Table 1] above, an emulsion polymerization functional polymer having a glass transition temperature (Tg) of 60°C to 200°C is included as a binder auxiliary agent, and for the manufacture of the binder auxiliary agent and the anode containing the same, an average particle size (D 50 It can be seen that when using a binder auxiliary material with a thickness of 50 nm to 3000 nm and manufacturing an anode by dry mixing, the carbon uniformity factor can be controlled to 12 to 30.

[0260]

[0261] <Experimental Example 2: Evaluation of Anode Properties>

[0262] (1) Tensile strength analysis

[0263] The tensile strength of the anodes prepared in the above examples and comparative examples was evaluated on freestanding films before rolling on a current collector, using a UTM device (AMETEK LS1 manufactured by Instron). Specifically, after fixing each freestanding film with jigs at both ends of the device, the tensile strength in the MD (Machine Direction) and TD (Transverse Direction) was measured while tensile at a speed of 2 mm / min.

[0264] (2) Interfacial adhesion analysis

[0265] To evaluate the interfacial adhesion strength of the anodes prepared in the above examples and comparative examples, each prepared anode was cut to a length of 150 mm and a width of 20 mm, and the surface of the anode was attached to a slide glass with a length of 75 mm and a width of 25 mm using double-sided tape in the longitudinal direction. That is, the slide glass was attached to an area corresponding to half of the anode in the longitudinal direction. Then, to ensure that the double-sided tape was uniformly attached, the evaluation sample was prepared by pressing at a speed of 1 at 95°C using a roll laminating machine (FANCYLOBBY, FANCO 325B6).

[0266] After preparing the evaluation sample, the slide glass portion of the evaluation sample was fixed to the sample stage of the UTM equipment (LLOYD LS1), and the anode half without the slide glass attached was connected to the load cell of the UTM equipment. The load applied to the load cell was measured while moving it up to 50 mm at a speed of 300 mm / min with a force applied at 90°. At this time, the average value of the load measured in the 20 mm to 40 mm section of the travel section was calculated, and this was repeated a total of 3 times to evaluate the average value as the interfacial adhesion strength (gf / 20 mm) of each sample.

[0267]

[0268] The anode properties evaluated by the above method are shown in [Table 2] below.

[0269]

[0270] Tensile strength (MD) (gf / mm²) 2 )Tensile Strength (TD)(gf / mm 2 Interfacial Adhesion (gf / 20mm) Example 15 1928 Example 25 81331 Example 35 31030 Example 45 2932 Example 55 41035 Example 65 41034 Example 75 61221 Example 8 461026 Example 9 42928 Reference Example 15 31014 Reference Example 23 8813 Comparative Example 12 9413 Comparative Example 26 212 Comparative Example 38 313 Comparative Example 4 2 7522

[0271]

[0272] As shown in [Table 2] above, in the case of Examples 1 to 9, which include an emulsion polymerization functional polymer that is a non-fluorinated polymer with a glass transition temperature (Tg) of 60°C to 200°C as a binder auxiliary agent and a carbon uniformity factor of 12 to 30, it can be seen that the physical properties of the anode, such as tensile strength and interfacial adhesion, are improved.

[0273] In the case of Reference Examples 1 and 2, which do not include a binder aid, the tensile strength shows a value suitable for use in a battery; however, due to the absence of the binder aid, it is difficult to control the carbon uniformity coefficient, resulting in a significantly lower uniformity coefficient than the example, and consequently, it can be confirmed that the interfacial adhesion also shows an inferior value. In other words, when a binder aid is not included, more fluorinated polymer is required as a binder than used in the example and comparative example to simultaneously secure strength and interfacial adhesion suitable for battery use; however, when a binder aid is included, it is easy to control the carbon uniformity coefficient and improve the physical properties of the anode even with a small amount of fluorinated polymer.

[0274] It can be seen that Comparative Examples 2 and 3, which include binder auxiliary agents but do not include emulsion polymerization functional polymers, exhibited generally low interfacial adhesion. Furthermore, unlike emulsion polymerization functional polymers, it is difficult to control the carbon uniformity coefficient, resulting in carbon coefficient values ​​that were lower or higher than those of the examples. It can be confirmed that when the uniformity coefficient is low, interfacial adhesion is reduced, and when the uniformity coefficient is high, interfacial adhesion is somewhat improved, but the strength is significantly lower than that of the examples.

[0275] In the case of Comparative Example 4, which includes an emulsion polymerization functional polymer as a binder auxiliary but uses a binder auxiliary raw material with a large particle size, it can be seen that the carbon uniformity coefficient increased because the mixing for anode manufacturing was uneven. Accordingly, it can be confirmed that both strength and interfacial adhesion are inferior compared to Examples 4 to 6, which use the same emulsion polymerization functional polymer.

[0276] In addition, in the case of Comparative Example 1, which was mixed in a wet manner, migration to the surface occurred during drying, and the carbon uniformity coefficient increased in the same way. It can be confirmed that both strength and interfacial adhesion decreased due to the high carbon uniformity coefficient.

[0277] Accordingly, it can be seen that physical properties such as strength and interfacial adhesion can be simultaneously improved when an emulsion polymerization functional polymer, which is a non-fluorinated polymer with a glass transition temperature (Tg) of 60°C to 200°C, is included as a binder auxiliary. Furthermore, it can be confirmed that such improvement in anode properties can be more effectively achieved when the carbon uniformity coefficient, which quantifies the degree of binder distribution within the anode, has a value of 12 to 30, and that the carbon uniformity coefficient can serve as a significant criterion for judging the suitability of the degree of binder distribution within the anode.

[0278]

[0279] <Experimental Example 3: Evaluation of Battery Characteristics>

[0280] (1) Manufacturing of coin cell batteries

[0281] One anode film of the above examples and comparative examples was placed on each side of an aluminum foil (thickness: 20 μm) serving as a current collector, and laminated through a compression roll at 25°C to produce an anode with a porosity of 24% to 26%.

[0282] A coin-type battery was manufactured by stamping the above positive electrode into a circular disc with a diameter of 14 mm, using a lithium metal (manufactured by Honjo) in the form of a circular disc with a diameter of 15 mm as the corresponding negative electrode, placing a polyethylene separator (thickness: 20 μm) in the form of a circular disc with a diameter of 19 mm between the positive electrode and the negative electrode, and then injecting an electrolyte. As the electrolyte, a solution containing LiPF6 at a concentration of 1 M with a volume ratio of ethylene carbonate to dimethyl carbonate of 7:3 was used.

[0283] (2) Manufacture of monocell batteries

[0284] One anode film of the above examples and comparative examples was placed on each side of an aluminum foil (thickness: 20 μm) serving as a current collector, and laminated through a compression roll at 25°C to produce an anode with a porosity of 24% to 26%.

[0285] The above anode is stamped into a rectangular shape measuring 30 mm × 42 mm, and a rectangular graphite electrode measuring 31 mm × 43 mm (4.45 mAh / cm²) is used as the corresponding cathode. 2 A pouch-type monocell battery was manufactured by using ) and placing a rectangular polyethylene separator (thickness: 20 μm) with dimensions of 35 mm × 45 mm between the anode and cathode, and then injecting an electrolyte.

[0286] As the above electrolyte, a solution containing ethylene carbonate and dimethyl carbonate in a volume ratio of 7:3 and LiPF6 at a concentration of 1M was used.

[0287] (3) Evaluation of capacity characteristics

[0288] After manufacturing the coin cell batteries containing the positive electrodes of the above examples and comparative examples, each coin cell battery was charged at 25°C in CC-CV mode at a rate of 0.1 C-rate until it reached 4.25 V, and discharged at a rate of 0.1 C-rate until it reached 3.0 V, and then the discharge capacity of the third cycle was measured to indicate the specific capacity.

[0289] (4) Evaluation of initial DC resistance (DCR) and life characteristics

[0290] After manufacturing the monocell batteries containing the positive electrodes of the above examples and comparative examples, each monocell battery was charged at 25°C in CC-CV mode at a rate of 0.1 C until it reached 4.2 V (termination current 0.05 C), and the battery was activated by discharging at a rate of 0.1 C until it reached 3.0 V. Subsequently, each monocell battery was charged at 25°C in CC-CV mode at a rate of 0.33 C until it reached 4.2 V, and discharged at a rate of 0.33 C until it reached 3.0 V, which was defined as one cycle. After performing the above cycle twice, the battery was charged in the same manner until it reached 4.2 V, and 50% of the capacity (mAh) measured during the previous discharge process was discharged again to reduce the State of Charge (SOC) to 50%. Subsequently, the potential change (△V) resulting from discharging for 10 seconds at a rate limit of 2.5 C-rate was measured, and the initial direct current resistance (DCR) was calculated using [Equation 2] below. I in [Equation 2] below was calculated using the capacity (mAh) measured during the discharge process at 0.1 C-rate in the preceding activation step and the rate limit of 2.5 C-rate.

[0291] [Equation 2]

[0292] Initial DC resistance (Ω) = △V(V) / I(A)

[0293] After measuring the initial DC as described above, discharge was performed at 25°C at a rate of 0.33 C until it reached 3.0 V. Subsequently, charging was performed in CC-CV mode at 45°C at a rate of 0.33 C until it reached 4.2 V (termination current 0.05 C), and then discharge was performed at the same temperature at a rate of 0.33 C until it reached 3.0 V. This was considered as one cycle and repeated for 100 cycles. The life characteristics were evaluated by determining the percentage of the discharge capacity of the 100th cycle relative to the discharge capacity of the first cycle as the capacity retention rate.

[0294] (5) Thermal stability evaluation

[0295] For the above monocell battery, to evaluate thermal stability, it was charged at 25°C in CC-CV mode at a rate of 0.33 C until it reached 4.2 V (termination current 0.05 C), and then stored at 60°C for 6 weeks. Afterward, it was discharged at 25°C in CC-CV mode at a rate of 0.33 C until it reached 3.0 V. Thermal stability was evaluated as the percentage of discharge capacity relative to the charge capacity.

[0296]

[0297] Among the battery characteristics evaluated by the above method, the battery characteristics for Reference Examples 1 and 2, which used the same binder system as the conventional one, are shown in [Table 3] below, and the battery characteristics for Examples and Comparative Examples, which used a binder auxiliary agent, are shown in [Table 4] below.

[0298]

[0299] Specific Capacity (mAh / g) Capacity Retention Rate (%) Initial DC Resistance (Ω) Thermal Stability (%) Reference Example 1 20894 1.0195 Reference Example 2 20996 0.9996

[0300]

[0301] Specific Capacity (mAh / g) Capacity Retention Rate (%) Initial DC Resistance (Ω) Thermal Stability (%) Example 1 20892 1.0793 Example 2 20895 1.0696 Example 3 20896 1.0594 Example 4 20895 1.0594 Example 5 20895 1.0694 Example 6 20794 1.0795 Example 7 20897 1.0796 Example 8 20895 1.0595 Example 9 20796 1.0394 Comparative Example 1 20081 -- Comparative Example 2 19987 1.0891 Comparative Example 3 20289 1.0890 Comparative Example 4 20491 1.0691

[0302]

[0303] As shown in [Table 3] and [Table 4] above, when a battery is manufactured using the cathode of Examples 1 to 9, which includes an emulsion polymerization functional polymer that is a non-fluorinated polymer with a glass transition temperature (Tg) of 60°C to 200°C as a binder auxiliary and has a carbon uniformity factor of 12 to 30, it can be seen that not only battery performance such as capacity and lifespan characteristics but also initial DC resistance and battery stability can be improved.

[0304] Furthermore, it can be confirmed that the anode of the example exhibits superior physical properties compared to Reference Examples 1 and 2, which do not contain a binder auxiliary agent, while also showing equivalent battery performance. Through this, it can be seen that a binder system containing a binder auxiliary agent can solve the problem of binder adhesion in conventional dry electrode manufacturing and exhibit equivalent or superior battery performance.

[0305] Therefore, it can be confirmed that when an emulsion polymerization functional polymer, which is a non-fluorinated polymer with a glass transition temperature (Tg) of 60°C to 200°C, is included as a binder auxiliary, not only the physical properties of the anode but also the performance and stability of the battery containing the anode can be improved. In addition, it can be confirmed that the carbon uniformity factor can serve as a significant criterion for judging the performance and stability of the battery.

[0306]

[0307] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

Claims

1. As an anode comprising an active material and a binder, The above anode further includes a binder aid, and The above binder auxiliary agent includes an emulsion polymerization functional polymer, and The above emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, and The above anode has a carbon uniformity coefficient of 12 to 30, anode.

2. In Claim 1, The porosity of the anode is 20% to 30%. anode.

3. In Claim 1, The content of the above binder auxiliary agent is 10 to 150 parts by weight based on 100 parts by weight of the binder, anode.

4. In Claim 1, The content of the binder and binder aid is 0.1% to 10% by weight based on the total weight of the anode, anode.

5. In Claim 1, The above emulsion polymerizable functional polymer comprises a repeating unit selected from the group consisting of acrylate-based repeating units, styrene-based repeating units, and combinations thereof. anode.

6. In Claim 1, The above emulsion polymerizable functional polymer comprises a repeating unit selected from the group consisting of acrylate-based repeating units, styrene-based repeating units, and combinations thereof, and The content of a repeating unit selected from the group consisting of acrylate-based repeating units, styrene-based repeating units, and combinations thereof in the above emulsion-polymerizable functional polymer is 10 mol% to 100 mol% based on the total repeating units in the emulsion-polymerizable functional polymer. anode.

7. In Claim 1, The binder comprises a material selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP), polyvinylidene fluoride-tetrafluoroethylene (PVdF-TFE), and combinations thereof. anode.

8. In Claim 1, The above active material comprises a lithium transition metal oxide, anode.

9. In Claim 1, The above active material includes a lithium transition metal oxide, and The above lithium transition metal oxide is represented by the following [Chemical Formula 1], anode. [Chemical Formula 1] Li a Ni b Co c M 1 d M 2 e O2 In the above chemical formula 1, M 1 is selected from the group consisting of Mn, Al, and combinations thereof, and M 2 is selected from the group consisting of Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, Y, Al, Co and combinations thereof, and a, b, c, d, and e are respectively such that a is 0.8≤a≤1.2, b is 0.6≤b<1, c is 0≤c≤0.2, d is 0≤d≤0.3, and e is 0≤e≤0.1, and b+c+d+e=1.

10. In Claim 1, The above positive electrode is for a secondary battery, and The above secondary battery comprises a liquid electrolyte, anode.

11. In Claim 1, The above anode is a dry electrode, anode.

12. As a method for manufacturing an anode, The above anode comprises an active material and a binder, and The above anode further includes a binder auxiliary agent, and The above binder auxiliary agent comprises an emulsion polymerization functional polymer, and The above emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, and The above anode has a carbon uniformity coefficient of 12 to 30, and The above manufacturing method includes the step of preparing a cathode composition by mixing an active material raw material, a binder raw material, and a binder auxiliary raw material. Method for manufacturing an anode.

13. In Claim 12, Average particle size (D) of the above binder auxiliary material 50 ) is 50 nm to 3000 nm, Method for manufacturing an anode.

14. A secondary battery including a positive electrode, The above anode comprises an active material and a binder, and The above anode further includes a binder auxiliary agent, and The above binder auxiliary agent comprises an emulsion polymerization functional polymer, and The above emulsion polymerization functional polymer is a non-fluorinated polymer having a glass transition temperature (Tg) of 60°C to 200°C, and The above anode has a carbon uniformity coefficient of 12 to 30, Secondary battery.

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