ÂNODO E MÉTODO DE FABRICAÇÃO DO MESMO

Abstract

The present invention relates to an anode for a lithium secondary battery, and a manufacturing method therefor. The anode for a lithium secondary battery comprises transition metal particles including iron and / or nickel in a carbon-based anode active material, wherein the concentration ratio of iron to nickel is controlled to satisfy a predetermined range. Therefore, the anode has excellent lifespan characteristics in high-temperature conditions and low electrical resistance in high-rate conditions. In addition, a lithium secondary battery comprising same can have excellent high-temperature lifespan characteristics and high-rate charge / discharge performance.

Description

1 / 35 “ANODE AND METHOD OF MANUFACTURING THE SAME” [Technical field]

[001] The present disclosure relates to a negative electrode for a secondary battery and a method of manufacturing the same.

[002] This application is based on and claims priority from South Korean Patent Application No. 10-2023-0158093 filed on November 15, 2023 with the South Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. [Fundamentals]

[003] Secondary batteries are widely used not only in small devices such as portable electronic devices, but also in medium and large devices such as battery packs for hybrid vehicles (HVs) and electric vehicles (EVs) or energy storage devices. Furthermore, given the recent growth in interest in environmental issues, research is being conducted on electric vehicles and hybrid electric vehicles (HEVs) that can replace fossil fuel-powered vehicles such as gasoline and diesel vehicles, which represent a major cause of air pollution, and research is also being actively conducted on high-capacity secondary batteries to power EVs and HEVs.

[004] Secondary batteries are rechargeable batteries, and may include conventional Ni / Cd batteries, Ni / MH batteries, and the newer lithium-ion batteries. Among these secondary batteries, lithium-ion batteries have little memory effect compared to Ni / Cd and Ni / MH batteries. Therefore, lithium-ion batteries can be freely charged and discharged, have a low self-discharge rate, and have high energy density. In addition, lithium-ion batteries can be manufactured in small and lightweight dimensions, resulting in high usability as a power source for Petition 870250081083, dated 09 / 09 / 2025, page 11 / 49 2 / 35 mobile devices. [Related technical document] [Patent document] Publication of South Korean Patent Application No. 10-2017-0011566. [Summary] [Technical problem]

[005] Correspondingly, an object of the present disclosure is to provide a negative electrode for secondary batteries having excellent service life characteristics under high temperature conditions and excellent electrical performance under high rate conditions, and a method for manufacturing the same. [Technical solution]

[006] To solve the problems described above, the present disclosure provides a negative electrode for a secondary battery, which includes a negative electrode current collector, and a negative electrode active layer provided on at least one surface of the negative electrode current collector and including a carbon-based negative electrode active material. The carbon-based negative electrode active material includes transition metal particles having magnetism, and the transition metal particles include iron and nickel. The carbon-based negative electrode active material includes the transition metal particles at a concentration of 1,200 ppm or less, and the iron-to-nickel (Fe / Ni) concentration ratio included in the carbon-based negative electrode active material is from 2.5 to 13.0.

[007] The iron concentration included in the carbon-based negative electrode active material can be from 0.1 ppm to 1,000 ppm.

[008] The concentration of nickel included in the carbon-based negative electrode active material can be from 0.01 ppm to 500 ppm. Petition 870250081083, dated 09 / 09 / 2025, page 12 / 49 3 / 35

[009] In addition, the carbon-based negative electrode active material may include transition metal particles at a concentration of 0.01 ppm to 1,100 ppm.

[010] Furthermore, transition metal particles having magnetism may include 50% or more of iron based on total weight.

[011] In addition, transition metal particles may also include at least one of cobalt, chromium, zinc, magnesium, manganese and copper.

[012] In addition, the carbon-based negative electrode active material can be artificial graphite in the form of secondary particles assembled from primary particles.

[013] Furthermore, according to one embodiment, the present disclosure provides a method for manufacturing a negative electrode for a secondary battery, which includes: applying a fluid negative electrode paste including a carbon-based negative electrode active material to at least one surface of a negative electrode current collector, followed by drying to form a negative electrode active layer. The carbon-based negative electrode active material includes transition metal particles, and the transition metal particles having magnetism include iron and nickel. The carbon-based negative electrode active material includes the transition metal particles at a concentration of 1,200 ppm or less, and the iron-to-nickel (Fe / Ni) concentration ratio included in the carbon-based negative electrode active material is 2.5 to 13.0.

[014] In the negative electrode manufacturing method, the carbon-based negative electrode active material is prepared by (S1) graphitizing a carbon feedstock; (S2) carbonizing the graphitized carbon feedstock in (S1); and (S3) adjusting the concentration of transition metal particles having magnetism present in the carbon feedstock by applying a Petition 870250081083, dated 09 / 09 / 2025, page 13 / 49 4 / 35 magnetic field at least once before and after (S2).

[015] In the method of manufacturing the negative electrode, in (S3), the magnetic field is applied with an intensity of 1,000 G to 40,000 G for 1 second to 600 seconds.

[016] Furthermore, in the method of manufacturing the negative electrode, (S3) is performed before or after (S2).

[017] Furthermore, in the manufacturing method of the negative electrode, an iron concentration can be from 0.1 ppm to 1,000 ppm.

[018] In the manufacturing method of the negative electrode, a nickel concentration can be from 0.01 ppm to 500 ppm.

[019] In addition, in the method of manufacturing the negative electrode, the transition metal particles may also include at least one of cobalt, chromium, zinc, magnesium, manganese and copper. [Beneficial Effects]

[020] The negative electrode for a secondary battery according to the present disclosure has advantages of excellent service life characteristics under high temperature conditions, and low electrical resistance under high rate conditions. Correspondingly, a lithium secondary battery including the negative electrode can have excellent service life characteristics at high temperatures, and high rate charge / discharge performance. [Detailed Description]

[021] The present disclosure may be modified in various ways and include various forms, and the forms will be described in detail in the detailed description.

[022] However, this disclosure is not intended to be limited to specific embodiments, but should be understood to include all modifications, equivalents or substitutes within the technical scope of this disclosure. Petition 870250081083, dated 09 / 09 / 2025, p. 14 / 49 5 / 35

[023] As used here, it should be understood that the terms “comprise,” “include,” and “have” are intended to specify the presence of an attribute, number, step, operation, component, part, or combination thereof, but do not in advance exclude the possibility of the presence or addition of one or more other attributes, numbers, steps, operations, components, parts, or combinations thereof.

[024] Furthermore, depending on the usage in question, “include as a major component” may mean including 50% by weight or more (or 50% by volume or more), 60% by weight or more (or 60% by volume or more), 70% by weight or more (or 70% by volume or more), 80% by weight or more (or 80% by volume or more), 90% by weight or more (or 90% by volume or more), or 95% by weight or more (or 95% by volume or more) of a component defined based on total weight (or total volume).For example, “including graphite as a major component as a negative electrode active material” could mean including 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, or 95% by weight or more of graphite based on the total weight of the negative electrode active material, and in some cases it could mean that the negative electrode active material is entirely made of graphite, so that it includes 100% by weight of graphite.

[025] Furthermore, depending on the usage in question, the “average particle size (D50)” refers to a particle size at a point where the volume percentage reaches 50% on the cumulative particle size distribution curve when the total volume is 100%, which means a particle size at the point where the volume becomes 50% when accumulated from a small particle size. The average particle size (D50) can be measured using, for example, a laser diffraction method, and the laser diffraction method can generally measure particle sizes from the submicron range to various Petition 870250081083, dated 09 / 09 / 2025, page 15 / 49 6 / 35 millimeters, and obtain results with high reproduction capacity and high resolution.

[026] Furthermore, depending on the usage in question, “magnetism” or “magnetic” refers to a property of a material to be magnetized. Magnetism can be classified into diamagnetism, paramagnetism, and ferromagnetism, depending on the direction of magnetization according to the direction of the magnetic field when an external magnetic field is applied or if an external magnetic field is applied during magnetization.

[027] As used here, the terms “about,” “approximately,” and “substantially” are intended to mean within or close to the range of values ​​or degrees to be considered for inherent manufacturing and material tolerances.

[028] Lithium secondary batteries are rechargeable power generation devices with a stacked structure of positive electrode / separator / negative electrode. When charging a lithium secondary battery, a lithium desorption reaction occurs at the positive electrode in the battery where the lithium contained in the positive electrode material is oxidized and released, and a lithium reaction occurs at the negative electrode where lithium is reduced and inserted into the active negative electrode material.

[029] For the negative electrode, graphite-based carbon-containing materials are widely used as the negative electrode active material. The average potential when a graphite-based carbon-containing material releases lithium is approximately 0.2 V (based on Li / Li+), and the discharge potential shows a relatively flat pattern. Therefore, when graphite-based carbon is used as a negative electrode active material, the secondary battery voltage is relatively high and constant, which is an advantage.

[030] The negative electrode active materials used for the negative electrode are amorphous or crystalline carbon, and crystalline carbon is mainly Petition 870250081083, dated 09 / 09 / 2025, page 16 / 49 7 / 35 is used due to its high capacity. This crystalline carbon includes graphite-based carbon such as natural graphite and artificial graphite.

[031] However, graphite-based carbon has different characteristics depending on the types. For example, natural graphite is inexpensive and exhibits excellent adhesion to a current collector, but is relatively inferior to artificial graphite in terms of high-rate charging / discharging performance or lifespan characteristics. However, since artificial graphite has fewer surface defects or functional groups, when used by mixing propylene carbonate (PC) in an electrolyte for the purpose of improving low-temperature performance, the propylene carbonate can exfoliate and destroy each layer that forms the graphite interlayer structure. This graphite exfoliation deteriorates the lifespan characteristics of the negative electrode under high-temperature conditions and increases resistance under high-rate conditions, which limits fast charging performance.

[032] With this in mind, the present disclosure provides a negative electrode technology for a secondary battery that can improve service life characteristics under high temperature conditions and electrical performance under high rate conditions.

[033] Hereafter, the present revelation will be described in greater detail. <Eletrodo negativo>

[034] According to one embodiment, the present disclosure provides a negative electrode for a secondary battery, including: a negative electrode current collector; and a negative electrode active layer provided on at least one surface of the negative electrode current collector and including a carbon-based negative electrode active material. The carbon-based negative electrode active material includes transition metal particles, the transition metal particles including iron and nickel. The carbon-based negative electrode active material Petition 870250081083, dated 09 / 09 / 2025, page 17 / 49 8 / 35 carbon-based materials include total transition metal particles including iron and nickel at a concentration of 1,200 ppm or less, and the concentration ratio between iron and nickel (Fe / Ni) included in the carbon-based negative electrode active material is 2.5 to 13.0.

[035] The negative electrode for a secondary battery according to the present disclosure may be a negative electrode applied to a lithium secondary battery. The negative electrode includes an active negative electrode layer on at least one surface of a negative electrode current collector. The active negative electrode layer implements negative electrode electrical activity, and includes an active negative electrode material that implements an electrochemical redox reaction during battery charging and discharging as a major component.

[036] The negative electrode active material may include a carbon-based negative electrode active material as a major component.

[037] For example, the carbon-based negative electrode active material may be included in an amount of 80 parts by weight to 99.8 parts by weight, based on the total weight of the negative electrode active layer. For example, the carbon-based negative electrode active material may be included in an amount of 95 parts by weight or more, 98 parts by weight or more, 84 parts by weight to 99.8 parts by weight, 90 parts by weight to 99.8 parts by weight, 94 parts by weight to 99.8 parts by weight, 88 parts by weight to 96 parts by weight, or 92 parts by weight to 97.5 parts by weight, based on the total weight of the negative electrode active layer.

[038] Furthermore, carbon-based negative electrode active material refers to a material containing carbon atoms as a major component, and this carbon-based negative electrode active material may include graphite. Graphite may include any one or more of natural graphite and artificial graphite. By Petition 870250081083, dated 09 / 09 / 2025, page 18 / 49 9 / 35 For example, the carbon-based negative electrode active material may include natural graphite or artificial graphite alone, and in some cases, may include a mixture of natural graphite and artificial graphite.

[039] For example, the carbon-based negative electrode active material may include natural graphite and artificial graphite in a weight ratio of 5 to 50:50 to 95, 20 to 45:55 to 80 or 30 to 50:50 to 70. In this case, the carbon-based negative electrode active material may enhance the adhesion between the negative electrode current collector and the negative electrode active layer, including natural graphite and artificial graphite in the aforementioned mixing ratio.

[040] Furthermore, the carbon-based negative electrode active material may include artificial graphite alone. According to one embodiment of the present disclosure, when artificial graphite is included alone in the negative electrode active layer, the service life of the negative electrode is significantly improved, which can be advantageous in conditions such as automotive batteries that must withstand frequent charging for a long time. In addition, batteries with artificial graphite are advantageous in fast charging and have excellent output performance compared to batteries with natural graphite.

[041] The carbon-based negative electrode active material may be secondary graphite particles with a spherical shape formed by an assembly of a plurality of primary graphite particles with a flake shape. Examples of flake-shaped graphite include, in addition to natural graphite and artificial graphite, calcined mesophase carbon (bulk mesophase) using tar and pitch as feedstocks, and graphitized coke (e.g., raw coke, green coke, pitch coke, needle coke, and petroleum coke), and may be assembled, for example, using multiple pieces of highly crystalline artificial graphite. Furthermore, a graphite assembly may be formed by an assembly of 2 to 100, or 3 to 20 pieces of flake-shaped graphite. Petition 870250081083, dated 09 / 09 / 2025, page 19 / 49 10 / 35

[042] The average particle diameter (D50) of secondary particles can be in a range of 1 μm to 50 μm. For example, the average particle diameter (D50) of secondary particles can be in a range of 1 μm to 40 μm; 1 μm to 30 μm; 10 μm to 40 μm; 15 μm to 30 μm; 25 μm to 50 μm; 11 μm to 19 μm; 15 μm to 25 μm; 20 μm to 30 μm; 1 μm to 20 μm; 1 μm to 10 μm; 5 μm to 15 μm; 10 μm to 20 μm; 15 μm to 30 pm; 15 pm to 20 pm; 21 pm to 26 pm; 25 pm to 30 pm; 11 pm to 17 pm; 16 pm to 23 pm; 2 pm to 7 pm; 0.5 pm to 5 pm; or 1 pm to 3 pm. It may be advantageous to make a particle size smaller in order to maximize the degree of disorder in the direction of expansion of each particle, thus suppressing the expansion of the particles due to lithium ion charging.However, when the particle size of the carbon-based negative electrode active material is less than 1.0 µm, the number of particles per unit volume increases, a large amount of binder is required, and the sphericity and spheroidization yield may be reduced. On the other hand, when the maximum particle size exceeds 50 µm, the expansion rate of the negative electrode active material during secondary battery charging and discharging increases significantly, and as charging and discharging are repeated, the bonding between the negative electrode active material particles and the agglutination between the negative electrode active material particles and the current collector deteriorates, which can significantly reduce the cycle characteristics.

[043] In addition, the carbon-based negative electrode active material may have a form in which transition metal particles are uniformly dispersed. Transition metal particles refer to particles containing a transition metal, and the transition metal may be included in the form of a transition metal or a transition metal alloy, a transition metal oxide, a transition metal nitride, or a transition metal phosphate.

[044] According to one embodiment, the transition metal particles Petition 870250081083, dated 09 / 09 / 2025, page 20 / 49 11 / 35 include magnetizable transition metals such as, for example, iron (Fe) and nickel (Ni). These transition metal particles can be included in a process to fabricate a carbon-based negative electrode active material. The present disclosure can further improve the charging / unloading performance of the carbon-based negative electrode active material under high rate and / or high temperature conditions by including the transition metal particles in the carbon-based negative electrode active material of the negative electrode. The transition metal particles can include iron and nickel in a predetermined concentration range, respectively, and the iron and nickel can have a predetermined concentration ratio. The concentration of the transition metal particles and / or the transition metal can be measured using, for example, an inductively coupled plasma optical emission spectrometer (ICP-OES).

[045] For example, iron can be included in the carbon-based negative electrode active material at a concentration of 0.1 ppm to 1,000 ppm. For example, iron can be included in the carbon-based negative electrode active material at a concentration of 0.1 ppm to 900 ppm; 0.1 ppm to 800 ppm; 0.1 ppm to 750 ppm; 0.1 ppm to 500 ppm; 0.1 ppm to 250 ppm; 0.1 ppm to 100 ppm; 0.1 ppm to 50 ppm; 0.1 ppm to 10 ppm; 0.1 ppm to 5 ppm; 0.1 ppm to 1 ppm; 0.5 ppm to 4 ppm; 10 ppm to 990 ppm; 100 ppm to 990 ppm; 200 ppm to 990 ppm; 500 ppm to 990 ppm; 750 ppm to 990 ppm; 1.0 ppm to 4.9 ppm; 0.3 ppm to 1.8 ppm; or 0.1 ppm to 0.9 ppm.

[046] In addition, nickel can be included in the carbon-based negative electrode active material at a concentration of 0.01 ppm to 500 ppm. For example, nickel can be included at a concentration of 0.01 ppm to 300 ppm; 0.01 ppm to 200 ppm; 0.01 ppm to 150 ppm; 0.01 ppm to 115 ppm; 0.01 ppm to 100 ppm; 0.01 ppm to 75 ppm; 0.01 ppm to 50 ppm; 0.01 ppm to 25 ppm; 0.01 ppm to 10 ppm; 0.01 ppm to 5 ppm; 0.01 ppm to 3 ppm; 0.01 ppm to 1.5 ppm; 1 ppm to 3 ppm; 10 Petition 870250081083, dated 09 / 09 / 2025, page 21 / 49 12 / 35 ppm to 200 ppm; 50 ppm to 200 ppm 80 ppm to 150 ppm 110 ppm to 190 ppm 0.10 ppm to 0.95 ppm; or 0.2 ppm to 1.1 ppm.

[047] The carbon-based negative electrode active material may include total transition metal particles, including iron, nickel, and additional transition metals besides iron and nickel, at a concentration of 1,200 ppm or less. For example, the carbon-based negative electrode active material may include transition metal particles at a concentration of 0.01 ppm to 1,200 ppm; 0.01 ppm to 1,100 ppm; 0.05 ppm to 1,050 ppm; 0.1 ppm to 990 ppm; 0.1 ppm to 500 ppm; 0.1 ppm to 100 ppm; 0.1 ppm to 50 ppm; 0.1 ppm to 10 ppm; 0.1 ppm to 5 ppm; 0.1 ppm to 1 ppm; 0.1 ppm to 1 ppm; 0.1 ppm to 5 ppm; 0.1 ppm to 1 ppm; 0.5 ppm to 4 ppm; 110 ppm to 1,000 ppm; 110 ppm to 800 ppm; 110 ppm to 600 ppm; 110 ppm to 400 ppm; 200 ppm to 650 ppm; 200 ppm to 990 ppm; 500 ppm to 990 ppm; 800 ppm to 990 ppm; 1.0 ppm to 4.9 ppm; 0.8 ppm to 2.3 ppm; or 0.1 ppm to 0.9 ppm.

[048] According to one embodiment, the transition metal may be a transition metal having magnetism (magnetic transition metal), or, in some cases, a transition metal not having magnetism (non-magnetic transition metal). Alternatively, the transition metal may include both a magnetic transition metal and a non-magnetic transition metal. For example, the non-magnetic transition metal may be present in the form of an alloy with the magnetic transition metal, and thus may be detected together with the magnetic transition metal during detection.

[049] By controlling the concentration of total transition metal particles including iron, nickel, and additionally including transition metals in a carbon-based negative electrode active material within the above range, the present disclosure can suppress or prevent the reduction in charge mobility from the positive electrode during the charging / discharging of a secondary battery due to an excessive concentration exceeding the upper limit. Petition 870250081083, dated 09 / 09 / 2025, p. 22 / 49 13 / 35 described above. For example, by controlling the concentration of transition metal particles in the carbon-based negative electrode active material within the above range, side reactions with the electrolyte during secondary battery charging / discharging are suppressed, thus suppressing or preventing the reduction in initial efficiency, and gas generation due to electrolyte decomposition is also suppressed, thereby improving secondary battery safety. Furthermore, the reduction in negative electrode capacity during high-rate charging and discharging, or fire or explosion occurring through various secondary battery mechanisms, can be suppressed or prevented.

[050] According to one embodiment, the iron-to-nickel (Fe / Ni) concentration ratio included in the carbon-based negative electrode active material may be in a range of 2.5 to 13.0. For example, the iron-to-nickel (Fe / Ni) concentration ratio included in the carbon-based negative electrode active material may be in a range of 2.5 to 12.0; 2.5 to 10.0; 2.5 to 8.0; 2.5 to 5.5; 2.5 to 4.5; 2.5 to 4.1; 2.5 to 3.9; 3.25 to 9.5; 3.2 to 8.5; 3.2 to 6.5; 3.2 to 4.5; 3.2 to 3.9; 3.5 to 8.5; 4.0 to 5.5; 5.0 to 8.5; 6.0 to 13.0; 9.0 to 13.0; 2.8 to 12.5; or 3.2 to 7.9.

[051] When the concentration ratio between iron and nickel contained in the carbon-based negative electrode active material is adjusted within the above range, the present disclosure can suppress or prevent an increase in the electrical resistance of the negative electrode during high-rate charging and discharging and a reduction in service life during high-temperature charging and discharging.

[052] Transition metal particles may additionally include transition metal elements besides iron and nickel. For example, transition metal particles may also include one or more of cobalt, chromium, zinc, magnesium, manganese, and copper. Transition metals may be included in Petition 870250081083, dated 09 / 09 / 2025, page 23 / 49 14 / 35 particles in the form of a transition metal or alloy, a transition metal oxide, a transition metal nitride or a transition metal phosphate.

[053] In this case, transition metal particles having magnetism may include iron in an amount of 50% or more based on the total weight. For example, transition metal particles may include iron in an amount of 50% to 95%; 50% to 90%; 55% to 90%; 60% to 90%; 65% to 90%; 75% to 90%; 80% to 90%; 55% to 85%; 55% to 80%; 60% to 80%; 60% to 70%; 70% to 85%; 58% to 69%; 62% to 81%; or 76% to 89%.

[054] The present invention has an advantage in that the electrical conductivity of the negative electrode can be increased without causing a side reaction with the electrolyte impregnated in the active layer of the negative electrode during charging and discharging of the secondary battery, provided that the iron ratio included in the transition metal particles satisfies the above range.

[055] However, the active negative electrode layer according to the present disclosure may optionally also include a conductive material, a binder, and other additives together with the carbon-based active negative electrode material as the main component, as needed.

[056] The conductive material may include one or more of, but is not limited to, carbon black, acetylene black, Ketjen black, carbon nanotubes and carbon fibers.

[057] As an example, the active negative electrode layer may include, as the conductive material, carbon black, carbon nanotubes and carbon fibers, either alone or in combination.

[058] At this point, the conductive material content can be 0.1 parts by weight to 10 parts by weight, based on 100 parts by weight total of the active negative electrode layer. For example, the conductive material content can be 0.1 parts by weight to 8 parts by weight, 0.1 parts by weight to 5 parts by weight, 0.1 Petition 870250081083, dated 09 / 09 / 2025, page 24 / 49 15 / 35 parts by weight to 3 parts by weight, 2 parts by weight to 6 parts by weight, or 0.5 parts by weight to 2 parts by weight, based on 100 parts by weight total of the negative electrode active layer. By controlling the content of the conductive material to the range as described above, the present disclosure can suppress the negative electrode resistance from increasing due to a low content of conductive material, thus suppressing the charging capacity from being reduced, and can suppress the content of the negative electrode active material from decreasing due to an excess amount of conductive material, thus suppressing the charging capacity from being reduced, or suppress the fast charging characteristics from decreasing due to an increase in the amount of charging of the negative electrode active layer.

[059] The binder is a component that aids in bonding the active material of the negative electrode and the conductive material, and assists in connecting it to a current collector. The binder may be appropriately applied within a range that does not deteriorate the electrical properties of the electrode. The binder may include one or more of the following: polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-coHFP), polyvinylidene fluoride (PVdF), polyacrylonitrile, poly(methyl methacrylate), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer, ethylene-propylene-diene sulfonated monomer, styrene-butadiene rubber (SBR), and fluororubber.

[060] The binder content can be from 0.1 parts by weight to 10 parts by weight, based on 100 parts by weight total of the active negative electrode layer. For example, the binder content can be from 0.1 parts by weight to 8 parts by weight, 0.1 parts by weight to 5 parts by weight, 0.1 parts by weight to 3 parts by weight, or 2 parts by weight to 6 parts by weight, based on 100 parts by weight total of the active negative electrode layer. By controlling the content Petition 870250081083, dated 09 / 09 / 2025, page 25 / 49 16 / 35 of the binder included in the active layer of the negative electrode to the above range, the present disclosure can suppress the adhesion of the active layer from deteriorating due to a low binder content or suppress the electrical properties of the electrode from deteriorating due to an excessive amount of binder.

[061] Furthermore, the average thickness of the negative electrode active layer can be in a range of 50 μm to 500 μm. For example, the average thickness of the negative electrode active layer can be in a range of 100 pm to 400 μm; 200 pm to 350 pm; 50 pm to 180 pm; 80 pm to 150 pm; 100 pm to 250 pm; 100 pm to 250 pm; or 130 pm to 190 pm. By controlling the average thickness of the negative electrode active layer within the above range, the present disclosure can implement high adhesion between the negative electrode active layer and the negative electrode current collector, as well as a high negative electrode energy density.

[062] Furthermore, the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, copper, stainless steel, nickel, titanium, and calcined carbon can be used as the negative electrode current collector, and in the case of copper or stainless steel, a surface of material treated with carbon, nickel, titanium, or silver can also be used. In addition, the average thickness of the negative electrode current collector can be appropriately applied from 1 µm to 500 µm considering the conductivity and the total thickness of the negative electrode to be manufactured.

[063] With the configuration described above, the negative electrode according to the present disclosure has advantages of excellent service life characteristics under high temperature conditions and low electrical resistance under high rate conditions. Correspondingly, a secondary lithium battery that includes the negative electrode of the present disclosure can have excellent service life characteristics at high temperature and high rate charging / discharging performance. Petition 870250081083, dated 09 / 09 / 2025, p. 26 / 49 17 / 35<Método de fabricação de um eletrodo negativo>

[064] According to one embodiment, the present disclosure provides a method for manufacturing a negative electrode for a secondary battery, including: applying a fluid negative electrode paste including a carbon-based negative electrode active material to at least one surface of a negative electrode current collector, followed by drying to form a negative electrode active layer. The carbon-based negative electrode active material includes transition metal particles, and the transition metal particles include iron and nickel. The carbon-based negative electrode active material includes total transition metal particles including iron and nickel at a concentration of 1,200 ppm or less, and the iron-to-nickel (Fe / Ni) concentration ratio included in the carbon-based negative electrode active material is 2.5 to 13.0.

[065] The method for manufacturing a negative electrode according to the present disclosure refers to the method for manufacturing the negative electrode described earlier in the present disclosure. The method for manufacturing the negative electrode can manufacture a negative electrode for a secondary lithium battery by applying a fluid negative electrode paste to a negative electrode current collector and drying the applied fluid negative electrode paste to form an active negative electrode layer.

[066] The negative electrode fluid paste may include a carbon-based negative electrode active material as a major component, and the carbon-based negative electrode active material may have a form in which transition metal particles are uniformly dispersed. Transition metal particles refer to particles that include both magnetic and non-magnetic transition metal, or both types of transition metals, and the transition metal may be included in the form of a single transition metal or an alloy of two types of magnetic or non-magnetic transition metals, one Petition 870250081083, dated 09 / 09 / 2025, page 27 / 49 18 / 35 transition metal oxide, a transition metal nitride, or a transition metal phosphate. Transition metal particles include iron (Fe) and nickel (Ni) as magnetizable transition metals.

[067] The carbon-based negative electrode active material is prepared by (S1) graphitizing a carbon feedstock; (S2) carbonizing the graphitized carbon feedstock in (S1); and (S3) adjusting the concentration of transition metal particles having magnetism present in the carbon feedstock by applying a magnetic field at least once before and after (S2).

[068] According to one embodiment, the graphitization step (S1) refers to a heat treatment process of a carbon feedstock at a temperature of 2,500 °C or higher to convert a disordered carbon feedstock structure into an ordered van der Waals graphite structure.

[069] “Carbon feedstock” may include at least one of the following: needle coke, mosaic coke, coal tar pitch and resin pitch.

[070] The graphitization step (S1) can be carried out using a device such as an Acheson graphitization furnace, a box-type graphitization furnace or a longitudinal graphitization furnace.

[071] The graphitization step (S1) can be applied at any heat treatment temperature capable of inducing a physical change in the structure of the irregular carbon feedstock into an ordered structure like graphite, without being particularly limited. For example, the graphitization step (S1) can be carried out at a temperature in a range of 2,000 °C to 3,500 °C; 2,500 °C to 3,500 °C; 2,800 °C to 3,500 °C; or 2,800 °C to 3,200 °C.

[072] The present disclosure can readily induce a change in the physical structure of a carbon feedstock by carrying out the graphitization step (S1) in the above temperature range. Correspondingly, the product Petition 870250081083, dated 09 / 09 / 2025, page 28 / 49 The 19 / 35 alloy thus obtained has high crystallinity and, therefore, excellent electrical properties when applied to the negative electrode. Furthermore, since the sublimation phenomenon on the surface of the carbon raw material is suppressed during heat treatment, there is an advantage of excellent process efficiency.

[073] The carbon feedstock obtained in the graphitization step (S1) can be a carbon feedstock from which a portion of the carbon feedstock present on top of the graphitized carbon feedstock has been removed. When the carbon feedstock is graphitized, foreign substances such as transition metals and non-metals present within the carbon feedstock can be volatilized. However, in the case of certain transition metals, since the boiling point is equal to or slightly higher than the graphitization temperature, the transition metals may not be completely volatilized and may remain partially on top of the graphitized carbon feedstock. Correspondingly, in step (S1), when the graphitized carbon feedstock is removed from the reactor, a predetermined carbon feedstock located on top can be removed and obtained.The carbon feedstock to be removed may be a carbon feedstock that has been introduced into the reactor and is present at a depth ratio of 10% or less; 5% or less; or 3% or less based on the total depth of the carbon feedstock above the surface of the carbon feedstock at the same depth.

[074] Next, the carbonization step of the graphitized carbon feedstock (S2) refers to a process of assembling and compacting the graphitized carbon feedstock. In this sense, the present disclosure can perform carbonization in a state where the graphitized carbon feedstock and pitch are mixed.

[075] The graphitized carbon feedstock from the graphitization step (S1) can have a spherical secondary particle shape, with the primary particles assembling in flake form. When the graphitized carbon feedstock is Petition 870250081083, dated 09 / 09 / 2025, p. 29 / 49 20 / 35 uniformly mixed with pitch and then carbonized, the mixed pitch fixes the adsorbed carbon raw materials on the surface of the carbon raw material, so that more stable spherical secondary particles can be obtained. Furthermore, since the density of the spherical secondary particles increases due to the pitch on the surface, a high energy density of the negative electrode active layer can be implemented.

[076] “Pitch” is primarily a material made from coal or petrochemical process byproducts, and can be either a commonly used solid pitch or liquid pitch. Solid pitch can be obtained by grinding coal tar pitch, petroleum pitch, synthetic pitch, or wood tar pitch. Liquid pitch can be manufactured by dissolving liquid resin or solid pitch in a solvent, followed by coating and carbonization. The solvents that can be used are hexane, toluene, tetrahydrofuran (THF), quinoline, N-methylpyrrolidone (NMP), or ethanol.

[077] Solid pitch can have an average particle diameter (D50) of 1 μm to 7 μm, or 2 μm to 4 μm. When the average particle diameter (D50) of the solid pitch satisfies the range, the solid pitch can be uniformly distributed and mixed among the negative electrode active material particles. As a result, the surface of the negative electrode active material particles is coated more uniformly.

[078] Pitch can be used in an amount of 1 part by weight to 10 parts by weight; or 3 parts by weight to 5 parts by weight, based on 100 parts by weight of the graphitized carbon feedstock. By controlling the amount of pitch mixture during the carbonization of the graphitized carbon feedstock within the above range, the present invention can suppress or prevent a significant increase in the content of transition metal particles contained in the manufactured carbon-based negative electrode active material due to a pitch content higher than the upper limit described above. Furthermore, the present Petition 870250081083, dated 09 / 09 / 2025, page 30 / 49 21 / 35 revelation can suppress or prevent a deterioration in structural stability due to the insertion / desorption of lithium from the carbon-based negative electrode active material during the charging / discharging of a secondary battery due to a pitch mixture quantity lower than the lower limit described above.

[079] Furthermore, in step (S2), the graphitized carbon feedstock and pitch can be homogenized using a homogenization device to achieve a uniform mixture of the graphitized carbon feedstock and pitch. The homogenization device can be any homogenization device commonly applied in the art, without being particularly limited. For example, the homogenization device can be a mixing homogenizer (vertical / horizontal mixer) or an ultrasonic homogenizer.

[080] The carbonization step (S2) can be carried out at a predetermined temperature range. For example, the carbonization step (S2) can be carried out at a temperature in a range of 1,000 °C to 2,600 °C; 1,500 °C to 2,000 °C; or 1,500 °C to 1,600 °C.

[081] However, transition metal particles can be mixed into the carbon feedstock by the wear of a grinding device during the grinding process of the carbon feedstock before graphitizing the carbon feedstock, and, in some cases, can be mixed into the carbon feedstock by the wear of a homogenizing device during the carbonization of the graphitized carbon feedstock. In this way, the introduced transition metal particles can exhibit better electrical characteristics under high temperature conditions, although it is difficult to control the concentration of the transition metal particles, compared to a case where the transition metal particles are intentionally mixed into the carbon feedstock during the manufacturing process of a negative electrode-based active material. Petition 870250081083, dated 09 / 09 / 2025, page 31 / 49 22 / 35 carbon.

[082] Correspondingly, the method of manufacturing a negative electrode according to an embodiment of the present disclosure includes a step (S3) of adjusting the concentration of transition metal particles in the carbon-based negative electrode active material by applying a magnetic field to the carbon feedstock, before and / or after the step (S2) of carbonizing the graphitized carbon feedstock, thereby removing the transition metal particles.

[083] For example, transition metal particles can be removed by applying a magnetic field to the carbon feedstock before carbonization of the graphitized carbon feedstock (S2).

[084] Similarly, transition metal particles can be removed by applying a magnetic field to the carbon feedstock after carbonization of the graphitized carbon feedstock (S2).

[085] According to one embodiment, when the transition metal particles are magnetic metal particles, at this stage (S3), the transition metal particles can be easily removed by applying a magnetic field to the carbon feedstock. This makes it possible to adjust the concentration of transition metal particles included in the carbon-based negative electrode active material to be manufactured. However, when a magnetic field is applied to the graphitized carbon feedstock twice, the concentration of transition metal particles remaining in the carbon feedstock can be significantly reduced. In this case, since the concentration ratio between iron and nickel present in the carbon-based negative electrode active material is significantly reduced, the high-temperature charging / discharging performance may deteriorate or the electrical resistance of the negative electrode under high-rate conditions may increase.Therefore, it needs to be adjusted appropriately. Petition 870250081083, dated 09 / 09 / 2025, page 32 / 49 23 / 35

[086] The (S3) step of adjusting the concentration of transition metal particles can be performed for a given period of time with a magnetic field intensity that satisfies a given range using an electromagnet or a permanent magnet.

[087] For example, step (S3) can be performed by applying a magnetic field with an intensity in the range of 1,000 G to 40,000 G (Gauss). According to one embodiment, step (S3) can be performed by applying a magnetic field with an intensity in the range of 5,000 G to 40,000 G; 20,000 G to 40,000 G; or 36,000 G to 40,000 G.

[088] Furthermore, step (S3) can be executed for 1 second to 600 seconds, for example, 10 seconds to 600 seconds; 30 seconds to 600 seconds; 60 seconds to 600; 100 seconds to 500 seconds; 200 seconds to 400 seconds; or 250 seconds to 350 seconds.

[089] By adjusting the magnetic field intensity and application time of step (S3) to adjust the concentration of transition metal particles to the above range, the present disclosure can more readily adjust the concentration of transition metal particles in the carbon-based negative electrode active material to be prepared.

[090] The carbon-based negative electrode active material thus prepared includes transition metal particles, and the transition metal particles may include iron and nickel in a predetermined concentration range, and the iron and nickel may have a predetermined concentration ratio. The concentration of the transition metal particles and / or the transition metal can be measured using an inductively coupled plasma optical emission spectrometer (ICP-OES).

[091] For example, iron can be included in the carbon-based negative electrode active material at a concentration of 0.1 ppm to 1,000 ppm. By Petition 870250081083, dated 09 / 09 / 2025, page 33 / 49 24 / 35 For example, iron can be included in the carbon-based negative electrode active material at a concentration of 0.1 ppm to 900 ppm; 0.1 ppm to 800 ppm; 0.1 ppm to 750 ppm; 0.1 ppm to 500 ppm; 0.1 ppm to 250 ppm; 0.1 ppm to 100 ppm; 0.1 ppm to 50 ppm; 0.1 ppm to 10 ppm; 0.1 ppm to 5 ppm; 0.1 ppm to 1 ppm; 0.5 ppm to 4 ppm; 10 ppm to 990 ppm; 100 ppm to 990 ppm; 200 ppm to 990 ppm; 500 ppm to 990 ppm; 750 ppm to 990 ppm; 1.0 ppm to 4.9 ppm; 0.3 ppm to 1.8 ppm; or 0.1 ppm to 0.9 ppm.

[092] In addition, nickel can be included in the carbon-based negative electrode active material at a concentration of 0.01 ppm to 500 ppm. For example, nickel can be included in the carbon-based negative electrode active material at a concentration of 0.01 ppm to 300 ppm; 0.01 ppm to 200 ppm; 0.01 ppm to 150 ppm; 0.01 ppm to 115 ppm; 0.01 ppm to 100 ppm; 0.01 ppm to 75 ppm; 0.01 ppm to 50 ppm; 0.01 ppm to 25 ppm; 0.01 ppm to 10 ppm; 0.01 ppm to 5 ppm; 0.01 ppm to 3 ppm; 0.01 ppm to 1.5 ppm; 1 ppm to 3 ppm; 10 ppm to 200 ppm; 50 ppm to 200 ppm; 80 ppm to 150 ppm; 110 ppm to 190 ppm; 0.10 ppm to 0.95 ppm; or 0.2 ppm to 1.1 ppm.

[093] Furthermore, transition metal particles may additionally include transition metal elements besides iron and nickel that are magnetic. For example, the additionally included transition metal particles may also include at least one cobalt, which is magnetic, and chromium, zinc, magnesium, manganese, and copper, which are non-magnetic. Transition metals may be included in the particles in the form of a transition metal or an alloy of transition metals, a transition metal oxide, a transition metal nitride, or a transition metal phosphate. As described earlier, non-magnetic transition metals are present in the form of an alloy with magnetic transition metals, and therefore may be detected together with magnetic transition metals, for example, during capture for measurement. Petition 870250081083, dated 09 / 09 / 2025, pp. 34 / 49 25 / 35

[094] However, the application of the negative electrode fluid paste can be carried out by discharging and coating the negative electrode fluid paste containing a carbon-based negative electrode active material onto the surface of the moving negative electrode current collector. The process can be applied in any manner conventionally practiced in the art without limitation, but a die-coating method can be used. The die-coating method can be carried out using a grooved die having a shim to control the discharge conditions of the negative electrode fluid paste. In this case, by controlling the shape and position of the shim, the amount of loading and the thickness of the negative electrode fluid paste applied to the negative electrode current collector can be easily controlled.

[095] In addition, the negative electrode fluid paste includes a carbon-based negative electrode active material as a main component, and may optionally include a conductive material, a binder and other additives as needed. At this point, since the composition of the negative electrode fluid paste is the same as the negative electrode active layer formed from it, further description is omitted.

[096] Furthermore, drying of the negative electrode fluid paste can be applied in any manner conventionally applied in the technique for drying active electrode layers, without limitation. For example, drying can be performed by applying thermal energy to the negative electrode fluid paste using a hot air dryer, a vacuum oven, or similar.

[097] In addition, the manufacturing method according to the present disclosure may also include a lamination step of the active negative electrode layer formed by drying the fluid negative electrode paste. The lamination step is a step to increase the energy density of the active layer of Petition 870250081083, dated 09 / 09 / 2025, pp. 35 / 49 26 / 35 negative electrode by applying pressure to the surface of the active negative electrode layer formed using a roller press or similar. At this point, lamination can be carried out under temperature conditions higher than room temperature.

[098] For example, lamination can be carried out at a temperature in a range of 50 °C to 100 °C, for example, 60 °C to 100 °C; 75 °C to 100 °C; 85 °C to 100 °C; 50 °C to 90 °C; 60 °C to 80 °C; or 65 °C to 90 °C.

[099] Rolling can be carried out at a rolling speed in a range of 2 m / s 7 m / s, for example, 2 m / s 6.5 m / s; 2 m / s 6 m / s; 2 m / s 5.5 m / s; 2 m / s 5 m / s; 2 m / s 4.5 m / s; 2 m / s 4 m / s; 2.5 m / s 4 m / s; 2.5 m / s 3.5 m / s; 3.5 m / s 5 m / s; 5 m / s 7 m / s; 5.5 m / s 6.5 m / s or 6 m / s 7 m / s.

[0100] Lamination can be carried out under pressure conditions in a range of 50 MPa to 200 MPa, for example, it can be carried out under pressure conditions in the range of 50 MPa to 150 MPa; 50 MPa to 100 MPa; 100 MPa to 200 MPa; 150 MPa to 200 MPa or 80 MPa to 140 MPa.

[0101] By performing lamination under the temperature, speed and / or pressure conditions as described above, the present disclosure is capable of readily increasing the energy density of the negative electrode without damage to the active negative electrode layer.

[0102] With the previously described configuration of the method for manufacturing a negative electrode according to the present disclosure, transition metal particles including iron and nickel in a predetermined concentration and concentration ratio can be included in the carbon-based negative electrode active material. Correspondingly, the manufactured negative electrode has advantages of excellent service life characteristics under high temperature conditions and low electrical resistance under high rate conditions.

[0103] Hereafter, the present disclosure will be described in detail as Petition 870250081083, dated 09 / 09 / 2025, pp. 36 / 49 27 / 35 examples and comparative examples.

[0104] However, the following examples and examples are merely illustrative of the present revelation, and the content of the present revelation is not limited to the following examples and comparative examples. <Fabricação de eletrodo negativo> 1) Preparation of carbon-based negative electrode active material

[0105] As a carbon feedstock, a coke feedstock was prepared. The prepared coke feedstock was pulverized using a spray mill until the average particle size (D50) became 10 μm. The pulverized coke feedstock was granulated using a horizontal granulator at 800 °C for 24 hours.

[0106] Granulated coke feedstock graphitized by heat treatment at 2,800 °C for 400 hours using an Acheson graphitization apparatus. When the graphitized product was removed from the graphitization apparatus, the top product was removed from the product surface to a depth at a rate of 3% based on the total product depth, and the remaining product was obtained. The top product removal is indicated in Table 1 below.

[0107] By mixing 100 parts by weight of the graphitized product and 5 parts by weight of the solid-phase pitch in a vertical / horizontal mixer, and carbonizing the mixture for 24 hours at a temperature of 1,500 °C, an artificial graphite having a spherical secondary particle shape was prepared by assembling flake-type primary particles. However, before and / or after carbonization, a magnetic field of 30,000 G to 32,000 G was applied to the graphitized product using an electromagnet for 10 to 300 seconds, thus adjusting the concentration of transition metal particles present in the product. The timing of the concentration adjustment is indicated in Table 1 below.

[0108] The prepared artificial graphite was subjected to an analysis of Petition 870250081083, dated 09 / 09 / 2025, pp. 37 / 49 28 / 35 Inductively coupled plasma optical emission spectrometry (ICP-OES). For example, 100 g of each prepared artificial graphite were added to 200 ml of ethanol, and a Teflon magnet (magnetic field intensity: approximately 5,000 G ± 100 G) was introduced into the ethanol to which the artificial graphite was added, and mixed for 2 hours. After mixing was complete, the Teflon magnet was removed from the ethanol, placed in a Teflon vial, injected with 15 ml of aqua regia, and then heated to 150 °C for 3 hours. The heated aqua regia was cooled to room temperature, and ultrapure water was added to the cooled aqua regia to a total volume of 50 ml to prepare a sample material.Calibration curves for reference solutions of 0.1 mg / kg, 0.5 mg / kg, and 1.0 mg / kg were prepared using an inductively coupled plasma emission spectrometer (Model: OPTIMA AVIO 500, Manufacturer: PERKIN-ELMER), and an analysis was performed on the prepared sample materials. At this point, the method detection limit (MDL) was set to less than 50 μg / kg (< 50 μg / kg).

[0109] As a result, it was confirmed that the artificial graphite had particles containing iron (Fe), nickel (Ni), cobalt (Co), chromium (Cr), zinc (Zn), magnesium (Mg), manganese (Mn), and copper (Cu) uniformly dispersed within it. At this point, (1) the total transition metal concentration included in the artificial graphite, (2) the respective concentrations of iron (Fe) and nickel (Ni), and (3) the concentration ratio between iron and nickel are indicated in Table 1 below. [Table 1] Removal of the top graphitized product Application of a magnetic field Result of transition metal particle component analysis [ppm] Application timing Application time Total concentration Fe concentration Ni concentration Fe / Ni Preparation Example 1 Before carbonization 300 s 1 0.6 0.2 3 Preparation Example After carbonization 300 s 2 1.3 0.4 3.25 Petition 870250081083, dated 09 / 09 / 2025, pp. 38 / 49 29 / 35 Example 2 of Preparation 3 After carbonization 150 s 5 3.9 0.9 4.33 Example of Preparation 4 After carbonization 80 s 16 12.9 2.9 4.44 Example of Preparation 5 After carbonization 15 s 91 76 7.1 10.70 Example of Preparation 6 X After carbonization 10 s 160 95 30 3.17 Example of Preparation 7 X After carbonization 300 s 1.000 860 110 7.82 Example of Preparation 8 X After carbonization 200 s 1.000 830 74 11.22 Example of Preparation 9 Before and after carbonization 300 s 0.1 0.07 0.03 2.33 Example of Preparation 10 X Before and after carbonization 300 s 500 405 29 13.97 Example of Preparation 11 X Before carbonization 300 s 2,000 1,790 190 9.42 Example of Preparation 12 OX - 4,000 3,480 370 9.41 Example of Preparation 13 XX - 6,000 5,270 560 9.41 2) Manufacturing of a negative electrode

[0110] Carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) were prepared as binders. Then, 96 parts by weight of the artificial graphite manufactured in Preparation Examples 1 to 10, 1.5 parts by weight of carboxymethyl cellulose (CMC), and 2.5 parts by weight of styrene-butadiene rubber (SBR) were mixed with water to a solid content of 50% to prepare a fluid negative electrode paste. Petition 870250081083, dated 09 / 09 / 2025, pp. 39 / 49 30 / 35

[0111] The prepared negative electrode fluid paste was applied onto a copper foil (thickness: 10 μm) and transported by rollers (transport speed: 5 m / min) using a die coater.

[0112] The applied negative electrode fluid paste was dried with hot air to form an active negative electrode layer on the negative electrode current collector. The formed active negative electrode layer was laminated at 50±1 °C, a pressure of 100 to 150 MPa, and a transport speed of 3 m / s to fabricate a negative electrode for a secondary lithium battery (average thickness of the active negative electrode layer: 160±5 μm). The types of artificial graphite applied to each negative electrode are indicated in Table 2 below. [Table 2]_______________________________________________________________ Types of artificial graphite applied Example 1 Artificial graphite prepared in Preparation Example 1 Example 2 Artificial graphite prepared in Preparation Example 2 Example 3 Artificial graphite prepared in Preparation Example 3 Example 4 Artificial graphite prepared in Preparation Example 4 Example 5 Artificial graphite prepared in Preparation Example 5 Example 6 Artificial graphite prepared in Preparation Example 6 Example 7 Artificial graphite prepared in Preparation Example 7 Example 8 Artificial graphite prepared in Preparation Example 8 Comparative Example 1 Artificial graphite prepared in Preparation Example 9 Comparative Example 2 Artificial graphite prepared in Preparation Example 10 Comparative Example 3 Artificial graphite prepared in Preparation Example 11 Comparative Example 4 Artificial graphite prepared in Preparation Example 12 Comparative Example 5 Artificial graphite prepared in Preparation Example 13 Petition 870250081083, dated 09 / 09 / 2025, pages 40 / 49 31 / 35<Fabricação de bateria secundária de lítio>

[0113] As a positive electrode active material, LiNio,7Coo,iMno,iAlo,iO2 with a particle size of 5 μm was prepared, and mixed with a carbon-based conductive agent and binder, polyvinylidene fluoride in N-methylpyrrolidone (NMP) at a weight ratio of 94:3.3 to form a fluid paste, which was melted onto an aluminum foil, dried in a vacuum oven at 120 °C, and then rolled to fabricate a negative electrode.

[0114] A separator made of 18 μm of polypropylene was interposed between the positive electrode obtained above and the negative electrode manufactured in Examples 1 to 8 and Comparative Examples 1 to 5, respectively, and inserted into a housing, and then an electrolyte composition was injected to assemble a single cell for a secondary lithium battery.

[0115] The types of negative electrodes applied to each secondary lithium battery are indicated in Table 3 below. [Table 3] Types of negative electrodes applied Example 9 Negative electrode manufactured in Example 1 Example 10 Negative electrode manufactured in Example 2 Example 11 Negative electrode manufactured in Example 3 Example 12 Negative electrode manufactured in Example 4 Example 13 Negative electrode manufactured in Example 5 Example 14 Negative electrode manufactured in Example 6 Example 15 Negative electrode manufactured in Example 7 Example 16 Negative electrode manufactured in Example 8 Comparative Example 6 Negative electrode manufactured in Comparative Example 1 Comparative Example 7 Negative electrode manufactured in Comparative Example 2 Comparative Example 8 Negative electrode manufactured in Comparative Example 3 Comparative Example 9 Negative electrode manufactured in Comparative Example 4 Comparative Example 10 Negative electrode manufactured in Comparative Example 5 Petition 870250081083, dated 09 / 09 / 2025, pp. 41 / 49 32 / 35<Exemplo experimental>

[0116] In order to evaluate the performance of the negative electrode according to the present disclosure, the following experiments were carried out on the negative electrodes and secondary lithium batteries in the examples and in the comparative examples. 1) Evaluation of high-rate DC resistance of secondary batteries

[0117] The single cells manufactured in Examples 9 to 16 and in Comparative Examples 6 to 10 were charged at 0.1 C in a constant current constant voltage (CC-CV) mode at 25 °C to 4.25 V, and then discharged at 3.0 V at a constant current of 0.1 C to activate the single cells.

[0118] Each activated single cell was charged at 25 °C with a constant current of 2.5 C for 30 seconds to a state of charge (SOC) of 50%, and the DC internal resistance (DCIR) was measured. The measured results are shown in Table 4 below. 2) High-temperature service life assessment

[0119] The single cells manufactured in Examples 9 to 16 and in Comparative Examples 6 to 10 were charged at 0.1 C in a constant current constant voltage (CC-CV) mode at 25 °C to 4.25 V, and then discharged at 3.0 V at a constant current of 0.1 C to activate the single cells.

[0120] After the single cells were activated, constant current (DC) charging at 1C and constant current (DC) discharging at 1C at 45°C were defined as 1 cycle, and 300 charging and discharging cycles were performed on each single cell. The load capacity of the 1st cycle and the load capacity of the 300th cycle were then measured during the charging and discharging of each single cell. The high-temperature lifespan of each single cell was evaluated by calculating the load capacity retention rate of the 300th cycle based on the measured load capacity of the 1st cycle. The results Petition 870250081083, dated 09 / 09 / 2025, pp. 42 / 49 33 / 35 are indicated in Table 4 below. [Table 4] Negative Electrode Type DC Resistance [mΩ] Capacity Retention Rate at 300 Cycles [%] Example 9 Negative electrode manufactured in Example 1 1783 84.6 Example 10 Negative electrode manufactured in Example 2 1780 85.5 Example 11 Negative electrode manufactured in Example 3 1760 86.9 Example 12 Negative electrode manufactured in Example 4 1754 86.5 Example 13 Negative electrode manufactured in Example 5 1772 84.8 Example 14 Negative electrode manufactured in Example 6 1825 79.8 Example 15 Negative electrode manufactured in Example 7 1790 84.0 Example 16 Negative electrode manufactured in Example 8 1805 82.9 Comparative Example 6 Negative electrode manufactured in Comparative Example 1 1831 82.6 Comparative Example 7 Negative electrode manufactured in Comparative Example 2 1951 77.7 Comparative Example 8 Negative electrode manufactured in Comparative Example 3 1913 79.9 Comparative Example 9 Negative electrode manufactured in Comparative Example 4 1921 79.Example 1 Comparative 10 Negative electrode manufactured in Example 5 Comparative 1946 78.6

[0121] As indicated in Table 4 above, it can be observed that the negative electrode for a secondary lithium battery according to the present disclosure has low DC resistance during high-rate charging and discharging and excellent high-temperature charging and discharging performance. Petition 870250081083, dated 09 / 09 / 2025, pages 43 / 49 34 / 35

[0122] For example, the secondary battery in the example in which the concentration and concentration ratio between iron and nickel included in the carbon-based negative electrode active material satisfies a predetermined range had a low DC resistance of less than 1810 mΩ during high-rate charging / discharging at 2.5 C, and a high capacity retention rate of 83% or more during high-temperature charging / discharging.

[0123] However, the secondary battery in Comparative Example 6 had a significantly lower concentration of transition metal particles in the carbon-based negative electrode material compared to the Examples, but the concentration ratio between iron and nickel was significantly lower, so that the DC resistance exceeded 1800 mΩ during high-rate charging and discharging and the capacity retention rate was less than 83% during high-temperature charging / discharging.

[0124] This means that although a carbon-based negative electrode active material includes a certain amount of transition metal particles, when the iron and nickel concentrations and their concentration ratios meet a certain range, the DC resistance of the negative electrode during high-rate charging and discharging and the capacity retention rate during high-temperature charging and discharging can be improved.

[0125] From these results, it can be observed that the negative electrode for a secondary lithium battery according to the present disclosure has advantages of excellent service life characteristics under high temperature conditions and low electrical resistance under high rate conditions.

[0126] Based on the above, it will be assessed that the various modalities of the present disclosure have been described in this document for illustrative purposes, and Petition 870250081083, dated 09 / 09 / 2025, pp. 44 / 49 35 / 35 that various modifications may be made without departing from the scope and scope of the present disclosure.

[0127] Therefore, the technical scope of the present invention should not be limited to the content described in the detailed description of the descriptive report, but should be defined by the scope of the patent claims. Petition 870250081083, dated 09 / 09 / 2025, pp. 45 / 49

Claims

1 / 3 CLAIMS 1. Negative electrode for a secondary battery, the negative electrode being CHARACTERIZED in that it comprises: a negative electrode current collector; and a negative electrode active layer provided on at least one surface of the negative electrode current collector and including a carbon-based negative electrode active material, the carbon-based negative electrode active material including transition metal particles having magnetism, the transition metal particles including iron and nickel, the carbon-based negative electrode active material including the transition metal particles at a concentration of 1,200 ppm or less, and the Fe / Ni concentration ratio between iron and nickel included in the carbon-based negative electrode active material is from 2.5 to 13.

0.

2. Negative electrode for a secondary battery, according to claim 1, CHARACTERIZED in that the iron concentration included in the carbon-based negative electrode active material is from 0.1 ppm to 1,000 ppm.

3. Negative electrode for a secondary battery, according to claim 1, CHARACTERIZED in that the concentration of nickel included in the carbon-based negative electrode active material is from 0.01 ppm to 500 ppm.

4. Negative electrode for a secondary battery, according to claim 1, CHARACTERIZED in that the carbon-based negative electrode active material includes transition metal particles at a concentration of 0.01 ppm to 1,100 ppm.

5. Negative electrode for a secondary battery, according to Petition 870250081083, dated 09 / 09 / 2025, page 46 / 49 2 / 3 claim 1, CHARACTERIZED in that the transition metal particles having magnetism include 50% or more of iron based on total weight.

6. Negative electrode for a secondary battery, according to claim 1, CHARACTERIZED in that the transition metal particles having magnetism included in the carbon-based negative electrode active material further include at least one of cobalt, chromium, zinc, magnesium, manganese and copper.

7. Negative electrode for a secondary battery, according to claim 1, CHARACTERIZED in that the carbon-based active negative electrode material is an artificial graphite in the form of secondary particles assembled from primary particles.

8. A method for manufacturing a negative electrode for a secondary battery, the method being characterized in that it comprises: applying a fluid negative electrode paste including a carbon-based active negative electrode material to at least one surface of a negative electrode current collector, followed by drying the fluid negative electrode paste applied to the negative electrode current collector to form an active negative electrode layer, wherein the carbon-based active negative electrode material includes transition metal particles having magnetism, the transition metal particles include iron and nickel, the carbon-based active negative electrode material includes the transition metal particles at a concentration of 1,200 ppm or less, and an Fe / Ni concentration ratio between iron and nickel included in the carbon-based active negative electrode material is from 2.5 to 13.

0.

9. Method according to claim 8, CHARACTERIZED in that the carbon-based negative electrode active material is prepared by Petition 870250081083, dated 09 / 09 / 2025, page 47 / 49 3 / 3 (S1) graphitization of a carbon feedstock; (S2) carbonization of the graphitized carbon feedstock in (S1); and (S3) adjusting the concentration of transition metal particles having magnetism present in the carbon feedstock by applying a magnetic field to the carbon feedstock at least once before and after (S2).

10. Method according to claim 9, CHARACTERIZED in that, in (S3), the magnetic field is applied with an intensity of 1,000 G to 40,000 G for 1 to 600 seconds.

11. Method according to claim 9, CHARACTERIZED in that (S3) is executed before or after (S2).

12. Method according to claim 8, CHARACTERIZED in that the iron concentration included in the carbon-based negative electrode active material is from 0.1 ppm to 1,000 ppm.

13. Method according to claim 8, CHARACTERIZED in that the concentration of nickel included in the carbon-based negative electrode active material is from 0.01 ppm to 500 ppm.

14. Method according to claim 8, CHARACTERIZED in that the transition metal particles included in the carbon-based negative electrode active material further include at least one of cobalt, chromium, zinc, magnesium, manganese, and copper. Petition 870250081083, dated 09 / 09 / 2025, pp. 48 / 49