Electrode for lithium secondary battery and manufacturing method thereof

Abstract

According to an embodiment of the present application, an electrode for a lithium secondary battery includes an electrode active material layer including an electrode active material, a solid electrolyte, and a fibrous conductive material. The electrode active material includes a core particle and a coating layer covering at least a portion of a surface of the core particle and including a conductive particle. The ratio of the content of the conductive particles to the content of the fibrous conductive material is 0.01 to 2.0 based on the total weight of the electrode active material layer. According to an embodiment of the present application, a lithium secondary battery including the electrode for a lithium secondary battery can be provided.

Description

Technical Field

[0001] This invention relates to an electrode for lithium secondary batteries and a method for manufacturing the same. Background Technology

[0002] Rechargeable batteries are batteries that can be repeatedly charged and discharged. With the development of the information and communication and display industries, rechargeable batteries have been widely used as power sources for portable electronic communication devices such as cameras, mobile phones, and laptops. Furthermore, battery packs incorporating rechargeable batteries have recently been developed and are being used as power sources for environmentally friendly vehicles such as hybrid electric vehicles.

[0003] Examples of rechargeable batteries include lithium-ion batteries, nickel-cadmium batteries, and nickel-metal hydride batteries. Among them, lithium-ion batteries are receiving active research and development due to their high operating voltage, high energy density per unit weight, and advantages in charging speed and weight reduction.

[0004] Lithium-ion secondary batteries may include a positive electrode and a negative electrode. The positive and negative electrodes may contain electrode active materials capable of reversibly inserting and deintercalating lithium ions, generating current through chemical reactions on the electrodes. The electrodes of a lithium-ion secondary battery may contain conductive materials to improve electronic conductivity and may contain a solid electrolyte to improve lithium-ion conductivity. The electrodes of a lithium-ion secondary battery can be formed by coating a composition used to form the electrodes. For example, the composition used to form the electrodes can be prepared by mixing the electrode components in a solvent and may be in, for example, slurry form.

[0005] In recent years, with the continuous expansion of the application range of lithium-ion batteries, the demand for high capacity and output performance has also been increasing. However, due to the use of different types of materials in the electrode components, uneven distribution may occur in the electrode components during the manufacturing process of lithium-ion battery electrodes. In this case, the expected capacity level and output characteristics may not be achieved. Summary of the Invention

[0006] One object of this application is to provide an electrode for a lithium secondary battery having improved ionic conductivity and electronic conductivity.

[0007] Another object of this application is to provide a method for manufacturing an electrode for a lithium secondary battery, the electrode having improved ionic conductivity and electronic conductivity.

[0008] According to an exemplary embodiment of this application, an electrode for a lithium secondary battery includes an electrode active material layer comprising an electrode active material, a solid electrolyte, and a fibrous conductive material. The electrode active material includes core particles and a coating covering at least a portion of the surface of the core particles and comprising conductive particles. Based on the total weight of the electrode active material layer, the ratio of the conductive particle content to the fibrous conductive material content is from 0.01 to 2.0.

[0009] In some implementations, the conductive particles may include dot-shaped conductive materials.

[0010] In some implementations, the content of the fibrous conductive material can be from 0.5% to 2.5% by weight, based on the total weight of the electrode active material layer.

[0011] In some implementations, the coating content can be from 0.1 parts by weight to 3 parts by weight based on 100 parts by weight of core particles.

[0012] In some implementations, the specific surface area of ​​the fibrous conductive material can be 0.1 m². 2 / g to 3000m 2 / g.

[0013] In some implementations, the diameter of the fibrous conductive material can be from 0.4 nm to 400 nm.

[0014] In some implementations, the ratio of the content of conductive particles to the content of fibrous conductive material can be from 0.1 to 1.0.

[0015] In some implementations, the coating may partially cover the surface of the core particle.

[0016] In some implementations, the coating may include a third pattern having a web-like shape.

[0017] In some embodiments, the coating may also include a pattern having an island-like shape or a pattern having a chain-like shape.

[0018] In some implementations, the median particle size (D) of the core particles 50 The diameter can range from 1μm to 20μm.

[0019] In some implementations, the electrode active material layer may also include an adhesive.

[0020] In a method for manufacturing an electrode for a lithium secondary battery according to an exemplary embodiment of this application, a coating comprising conductive particles may be formed on core particles to prepare an electrode active material. The electrode active material may be mixed with a solid electrolyte. The mixture of the electrode active material and the solid electrolyte may be mixed with a fibrous conductive material to form an electrode slurry. The electrode slurry may be coated onto an electrode current collector to form an electrode active material layer. Based on the total weight of the electrode slurry, the ratio of the conductive particle content to the fibrous conductive material content may be from 0.01 to 2.0.

[0021] In some implementations, the conductive particles may include dot-shaped conductive materials.

[0022] In some implementations, the coating may be partially formed on the core particles.

[0023] In some implementations, the coating may include a mesh pattern formed by conductive particles that are continuously connected to each other.

[0024] In some embodiments, during the step of mixing the electrode active material with the solid electrolyte, the solid electrolyte may be wound around a mesh pattern and may be in contact with the surface of the core particles.

[0025] In some implementations, the method may also include adding a binder to the electrode slurry.

[0026] According to embodiments of this application, the electrode for a lithium secondary battery may include an electrode active material, a solid electrolyte, and a fibrous conductive material. Therefore, the migration of lithium ions and electrons within the electrode for a lithium secondary battery can be facilitated.

[0027] The electrode active material may include core particles and a coating covering the core particles. The coating may contain conductive particles. The ratio of fibrous conductive material to conductive particles may be within a predetermined range. The electrode active material and solid electrolyte may be uniformly dispersed in the electrode for a lithium secondary battery, thereby forming a uniform electronic conductive network within the electrode and reducing the interfacial resistance of the electrode active material.

[0028] The coating can partially cover the core particles and can exhibit a chain-like or network-like morphology. It can increase the contact between the electrode active material and the solid electrolyte, thereby further improving ionic and electronic conductivity. The output characteristics and energy density of lithium-ion batteries can be enhanced.

[0029] The lithium secondary battery according to the embodiments of this application can be widely used in green technology fields, such as electric vehicles, battery charging stations, and solar and wind power generation using batteries. Furthermore, the lithium secondary battery according to the embodiments of this application can also be used in environmentally friendly electric vehicles, hybrid vehicles, etc., which aim to mitigate climate change by reducing air pollution and greenhouse gas emissions. Attached Figure Description

[0030] The above and other objects, features and advantages of this application will become clearer from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0031] Figure 1 A schematic diagram illustrating an electrode active material according to an exemplary embodiment;

[0032] Figure 2 This is a flowchart describing an electrode manufacturing method for a lithium secondary battery according to an exemplary embodiment;

[0033] Figure 3 and Figure 4 The schematic plan view and schematic cross-sectional view respectively illustrate a lithium secondary battery according to an exemplary embodiment;

[0034] Figure 5 The image shows a scanning electron microscope (SEM) image of the positive electrode active material layer prepared in Example 1; and

[0035] Figure 6 This is a scanning electron microscope (SEM) image of the positive electrode active material layer prepared in Comparative Example 1. Detailed Implementation

[0036] According to an embodiment of this application, an electrode for a lithium secondary battery is provided, the electrode comprising an electrode active material and a conductive material.

[0037] According to an embodiment of this application, a method for manufacturing the electrode described above for a lithium secondary battery is provided.

[0038] The terms “upper part”, “lower part”, “upper surface”, “lower surface”, and “bottom surface” used in this article refer to the relative positional relationship between the components and do not imply an absolute vertical direction.

[0039] Unless otherwise defined herein, when a part (e.g., a layer, membrane, film, region, or plate) is "on" or "above" another part, it includes not only the case where the part is "directly" on the other part, but also the case where there is another part between them.

[0040] The embodiments of this application will now be described in detail. However, these embodiments are merely illustrative, and this application is not limited to the specific embodiments described by example.

[0041] Electrodes used in lithium secondary batteries (hereinafter also referred to as "electrodes") may include an electrode active material layer containing electrode active material, solid electrolyte and conductive material.

[0042] Electrode active materials may include core particles and a coating covering the surface of the core particles. The core particles can reversibly insert and deintercalate lithium ions, providing electrode activity.

[0043] The coating may contain conductive particles. For example, conductive particles may be attached to the surface of the core particles to form a conductive coating.

[0044] A conductive coating can be formed on the surface of the core particles, providing additional pathways for electron migration. Therefore, for example, electrons can migrate smoothly within the electrode active material layer, and electron migration between the electrode current collector and the electrode active material layer can be facilitated. Furthermore, the interfacial resistance of the core particle surface can be reduced, thereby improving output characteristics.

[0045] In one embodiment, the desired level of electronic conductivity can still be achieved even if the amount of conductive material in the electrode active material layer is reduced due to the use of a coating. Therefore, the amount of conductive material can be reduced, while simultaneously decreasing the total contact area between the conductive material and the electrolyte, thereby suppressing side reactions.

[0046] Conductive materials may include fibrous conductive materials. For example, conductive materials may have a fibrous shape. Fiber shapes may include cylindrical, hollow, etc.

[0047] Because the electrode active material layer contains fibrous conductive material, an electronic conductive network can be widely formed inside the electrode. For example, when the fibrous conductive material is three-dimensionally dispersed in the electrode active material layer to form an electronic conductive network, electrons can easily migrate through the fibrous conductive material.

[0048] In addition, fibrous conductive materials can come into contact with the coating of electrode active materials to promote electron transport between electrode active materials and prevent the decrease in electronic conductivity caused by the addition of solid electrolytes.

[0049] The ratio of conductive particles to fibrous conductive material can be from 0.01 to 2.0. Within this range, the interfacial resistance of the electrode active material can be reduced, and the fibrous conductive material can be uniformly dispersed in the electrode active material layer, thereby improving electronic conductivity.

[0050] For example, when the ratio of conductive particles to fibrous conductive material is less than this range, the fibrous conductive material may hinder ion transport, thereby reducing energy density. Furthermore, side reactions between the conductive material and the solid electrolyte may increase, thus reducing electrode stability, capacity, and output characteristics. Further, the electronic conductivity network formed by the coated conductive particles may be insufficient, further reducing capacity and output characteristics.

[0051] For example, when the ratio of conductive particles to fibrous conductive material exceeds the aforementioned range, the coating content may increase relatively, while the contact area between the electrode active material and the solid electrolyte may decrease, thereby reducing lithium-ion mobility. Furthermore, the electronic conductive network formed by the fibrous conductive material may be insufficient, thus reducing electronic conductivity and deteriorating the output characteristics of the lithium secondary battery.

[0052] In some embodiments, the ratio of the content of conductive particles to the content of fibrous conductive material can be 0.01 to 1.8, 0.03 to 1.6, 0.05 to 1.5, 0.08 to 1.4, 0.1 to 1.2, 0.1 to 1.0, 0.15 to 0.8, 0.2 to 0.75, or 0.2 to 0.7.

[0053] Within the aforementioned range, electronic conductivity and ionic conductivity can be further improved, as can the initial efficiency, capacity characteristics, and output characteristics of lithium secondary batteries.

[0054] In some embodiments, fibrous conductive material may refer to conductive material having an aspect ratio of, for example, 2 or greater. Aspect ratio can refer to the ratio of the length to the diameter of the fibrous conductive material.

[0055] In one embodiment, the aspect ratio of the fibrous conductive material can be 2 or more, 5 or more, 10 or more, 50 or more, or 100 or more. For example, the aspect ratio of the fibrous conductive material can be 2-50000, 10-40000, 50-35000, or 100-30000. Within the above ranges, the dispersion of the fibrous conductive material can be further improved, and the electronic conductivity of the electrode can be further enhanced through the widely formed electronic conductive network.

[0056] In some embodiments, the fibrous conductive material may include carbon nanotubes (CNTs), carbon nanofibers (CNFs), metal fibers, vapor-grown carbon fibers (VGCFs), etc. Metal fibers may include metals such as copper (Cu), nickel (Ni), aluminum (Al), iron (Fe), silver (Ag), gold (Au), platinum (Pt), zinc (Zn), titanium (Ti), or alloys thereof.

[0057] In one embodiment, the fibrous conductive material may include carbon nanotubes (CNTs). For example, the fibrous conductive material may include single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), rope-shaped carbon nanotubes (rope CNTs), etc.

[0058] Carbon nanotubes possess high crystallinity and mechanical stability, which can further improve the electronic conductivity in the electrode active material layer, as well as the cycle life and output characteristics of lithium secondary batteries.

[0059] In some implementations, the specific surface area of ​​the fibrous conductive material can be 0.1 m². 2 / g to 3000m 2 / g. Specific surface area can be measured using the Brunauer-Emmett-Teller (BET) method.

[0060] In some implementations, the specific surface area of ​​the fibrous conductive material can be 0.3 m². 2 / g to 2500m 2 / g, 0.5m 2 / g to 2000m 2 / g, 0.7m 2 / g to 1500m 2 / g, 0.8m 2 / g to 1000m 2 / g, 0.9m 2 / g to 500m 2 / g or 1m 2 / g to 300m 2 / g.

[0061] Within the aforementioned range, electron migration can be further promoted and agglomeration caused by excessively high specific surface area can be suppressed, thereby further improving the dispersibility of fibrous conductive materials.

[0062] In some embodiments, the diameter of the fibrous conductive material can range from 0.4 nm to 400 nm. The diameter of the fibrous conductive material refers to its width along the minor axis. Within this range, the dispersibility of the fibrous conductive material can be further improved, and the contact between the electrode active material and the fibrous conductive material can be increased.

[0063] In one embodiment, the diameter of the fibrous conductive material can be 1 nm to 350 nm, 2 nm to 300 nm, 4 nm to 250 nm, 5 nm to 200 nm, 6 nm to 180 nm, 7 nm to 150 nm, 8 nm to 100 nm, 8.5 nm to 75 nm, or 9 nm to 50 nm.

[0064] In some embodiments, the length of the fibrous conductive material can be 5 μm to 200 μm, 10 μm to 180 μm, 15 μm to 160 μm, 20 μm to 150 μm, 25 μm to 130 μm, or 30 μm to 120 μm. The length of the fibrous conductive material refers to its width along its long axis. Within these ranges, electron migration between the electrode active materials can proceed smoothly, while preventing an increase in the gaps between the electrode active materials due to the fibrous conductive material, thereby improving energy density.

[0065] According to an exemplary embodiment, the conductive particles may include dot-shaped conductive materials. For example, the dot-shaped conductive materials may have a substantially spherical shape.

[0066] In some implementations, dot-shaped conductive materials may refer to conductive materials with an aspect ratio of 1.5 or less. For example, the aspect ratio of a dot-shaped conductive material can be from 0.5 to 1.5.

[0067] Because the conductive particles contain point-like conductive material, they can easily adhere to localized areas on the surface of the core particles. Therefore, while the conductive particles promote electron migration, they also facilitate contact between the solid electrolyte and the core particles, thereby further promoting ion migration.

[0068] For example, dot-shaped conductive materials may include carbon-based conductive materials, such as graphite, carbon black, graphene, and carbon nanotubes; or metal-based conductive materials, such as tin, tin oxide, titanium oxide, LaSrCoO3, LaSrMnO3, etc.

[0069] In one embodiment, the dot-like conductive material may include carbon black. For example, the dot-like conductive material may include acetylene black, furnace black, Ketjen black, channel black, etc.

[0070] Carbon black has high electronic conductivity, chemical stability and mechanical strength, which can further improve the output characteristics and stability of lithium secondary batteries.

[0071] In some implementations, the median particle size (D) of the dot-like conductive material 50 The median particle size can range from 10 nm to 100 nm, 10 nm to 60 nm, or 20 nm to 50 nm. 50 The median particle size (D) can be defined as the particle size at the 50th percentile point in a volume-based cumulative particle size distribution. For example, the median particle size can be measured using laser diffraction (e.g., Microtrac, MT 3000). 50 ).

[0072] In some embodiments, the content of the fibrous conductive material can be from 0.5% by weight (“wt%”) to 2.5% by weight, based on the total weight of the electrode active material layer.

[0073] In some implementations, the content of conductive particles can be from 0.1% by weight to 1.0% by weight, based on the total weight of the electrode active material layer.

[0074] When the ratio of fibrous conductive material to conductive particles meets the above-mentioned range, and the content of each is adjusted to within the above-mentioned range, a more uniform and extensive electronic conductive network can be formed within the electrode active material layer. Therefore, while suppressing the loss of ionic conductivity and energy density caused by conductive materials, electronic conductivity, capacity characteristics, and rate performance can be further improved.

[0075] In one embodiment, the content of the fibrous conductive material can be 0.7 wt% to 2.3 wt%, 0.8 wt% to 2.2 wt%, 0.8 wt% to 2.0 wt%, 0.9 wt% to 1.9 wt%, or 1.0 wt% to 1.8 wt%, depending on the total weight of the electrode active material layer.

[0076] Within the aforementioned range, high ionic conductivity can be achieved while further reducing the internal resistance of the electrode active material layer. Therefore, the initial efficiency, rate capability, and ionic conductivity of lithium-ion batteries can be further improved.

[0077] In one embodiment, the content of conductive particles can be 0.1 wt% to 0.97 wt%, 0.11 wt% to 0.95 wt%, 0.115 wt% to 0.93 wt%, 0.12 wt% to 0.90 wt%, or 0.125 wt% to 0.85 wt%, based on the total weight of the electrode active material layer.

[0078] Within the aforementioned range, the interfacial resistance of the electrode active materials can be reduced, and the electron and ion migration between the electrode active materials can be further promoted.

[0079] In some implementations, the coating content can be from 0.1% to 3% by weight based on 100% by weight of core particles. Within this range, the coating coverage can be appropriately adjusted to improve the electronic and ionic conductivity of the electrode active material.

[0080] In one embodiment, the coating content can be from 0.1 to 2.8 parts by weight, 0.11 to 2.5 parts by weight, 0.115 to 2.5 parts by weight, 0.12 to 2.2 parts by weight, or 0.12 to 2.0 parts by weight, based on 100 parts by weight (“wt parts”) of core particles.

[0081] In one embodiment, the coating may consist primarily of conductive particles. Therefore, it can prevent an increase in interfacial resistance caused by organic binders, etc., and can further improve electronic and ionic conductivity.

[0082] Solid electrolytes can provide additional channels for the migration of lithium ions within the electrode, thereby improving the capacity and output characteristics of lithium secondary batteries.

[0083] Solid electrolytes may include sulfide-based electrolytes, oxide-based electrolytes, and / or polymer electrolytes. Polymer electrolytes may include ion-conducting polymers or gel polymer electrolytes.

[0084] In one embodiment, the sulfide-based electrolyte can be represented by the following formula 1.

[0085] [Formula 1]

[0086] Li e Y f P g S h Z i

[0087] In Equation 1, e, f, g, h, and i can satisfy 0 < e < 12, 0 ≤ f ≤ 6, 0 ≤ g ≤ 6, 0 < h ≤ 12, and 0 ≤ i ≤ 9. Y can contain at least one element selected from B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, and W. Z can contain at least one element selected from F, Cl, Br, and I.

[0088] For example, sulfide-based electrolytes can be LPS-based solid electrolytes containing Li, P, and S, LGPS-based solid electrolytes containing Li, P, Ge, and S, or LSiPSCl-based solid electrolytes containing Li, Si, P, S, and Cl.

[0089] For example, Li₂S-P₂S₅ and Li₂S₅ can be used as sulfide-based electrolytes. 10 GeP2S 12 Li 10 SnP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li10 (Ge 0.5 Sn 0.5 )P2S 12 、Li 10 (Si 0.5 Sn 0.5 )P2S 12 、Li 10 GeP2S 11.7 O 0.3 、Li 9.6 P3S 12 、Li9P3S9O3、Li 10.35 Ge 1.35 P 1.65 S 12 、Li 10.35 Si 1.35 P 1.65 S 12 、Li 9.81 Sn 0.81 P 2.19 S 12 、Li 9.42 Si 1.02 P 2.1 S 9.96 O 2.04 、Li6PS5Cl, etc.

[0090] In one embodiment, the oxide-based electrolyte may include an ion-conductive compound containing a metal oxide and / or oxygen.

[0091] Examples of metal oxides include Al2O3, ZnO2, Ce2O3, TiO2, ZrO2, HfO2, MnO2, MgO, WO2, V2O5, etc.

[0092] Examples of ion-conductive compounds may include garnet compounds, such as LLZO compounds; perovskite compounds, such as LLTO compounds; NASICON compounds, such as Li 1+x Al x Ge 2-x (PO4)3(0 < x < 2), Li 1+ x Al x Ti 2-x (PO4)3(0 < x < 2), Li 1+x Ti 2-x-y Al x Si y (PO4) 3-y (0 ≤ x ≤ 1, 0 < y ≤ 1), LAGP compounds, LATP compounds, LiAl x Zr 2-x(PO4)3(0≤x≤1, 0≤y≤1), LiTi x Zr 2-x (PO4)3 (0≤x≤1, 0≤y≤1); LIPON compounds; Li6La2CaTa2O 12 ;Li6La2ANb2O 12 (where A is Ca or Sr); Li₂Nd₃TeSbO 12 Li3BO 2.5 N 0.5 ; Li9SiAlO8, etc.

[0093] In one embodiment, the solid electrolyte may include a sulfide-based electrolyte. Sulfide-based electrolytes can exhibit high compatibility and stability with electrode active materials, thereby further improving the electrochemical characteristics of lithium secondary batteries.

[0094] In some embodiments, the content of solid electrolyte can be 5-80 parts by weight, 10-70 parts by weight, or 15-60 parts by weight, based on 100 parts by weight of electrode active material. Within these ranges, the ionic conductivity in the electrode active material layer can be improved while preventing the energy density reduction caused by the solid electrolyte. Therefore, the capacity and output characteristics of the lithium secondary battery can be improved.

[0095] Figure 1 This is a schematic diagram illustrating an electrode active material according to an exemplary embodiment.

[0096] refer to Figure 1 The electrode active material 50 may include a core particle 10 and a coating 20 covering the surface of the core particle 10.

[0097] The coating 20 may be formed on a portion of the surface of the core particle 10. For example, the coating 20 may partially cover the surface of the core particle 10.

[0098] For example, when the coating completely covers the surface of the core particle, the contact between the core particle and the electrolyte may be reduced, thereby decreasing the migration rate of lithium ions on the core particle surface. This could consequently reduce the ionic conductivity in the electrode active material layer.

[0099] According to an exemplary embodiment, coating 20 may be formed only on a portion of the surface of core particle 10, thereby ensuring electronic conductivity through the conductive coating while improving lithium-ion conductivity.

[0100] In one embodiment, coating 20 may cover more than 10%, more than 20%, or more than 30% of the surface of core particle 10. In another embodiment, coating 20 may cover less than 80%, less than 70%, less than 60%, or less than 50% of the surface of core particle 10.

[0101] Within the aforementioned range, ionic conductivity can be increased, while electronic conductivity and stability of the electrode active material 50 can be improved. Therefore, the output, capacity, and cycle life characteristics of lithium-ion secondary batteries can be further enhanced.

[0102] In some embodiments, coating 20 may include a first pattern 22 having an island-like shape. The island-like shape may guide the form of the discretely spaced distribution of electroparticles and may have a spherical, hemispherical, cylindrical, elliptical, or irregular shape.

[0103] For example, the first pattern 22 may consist of each individual conductive particle dispersed on the surface of the core particle 10, or it may consist of a portion of conductive particles aggregated together.

[0104] Because the coating 20 includes the first pattern 22, the ionic conductivity of the surface of the core particle 10 can be improved. Therefore, for example, the migration of lithium ions between the electrode active material 50 and the electrolyte can be promoted, thereby improving the capacity characteristics of the lithium secondary battery.

[0105] In some embodiments, coating 20 may include a second pattern 24 having a chain-like shape. The chain-like shape may refer to the form in which multiple conductive particles are connected in an extended chain-like manner.

[0106] For example, the second pattern 24 can be composed of a series of continuously connected conductive particles. The second pattern 24 can be straight, curved, bent, zigzag, wave, or arc-shaped, and may also include multiple branches extending from these shapes.

[0107] Because the coating includes the second pattern 24, the conductivity of the electrode active material can be improved, and the internal resistance of the electrode can be reduced. Therefore, the rate performance of the lithium secondary battery can be improved.

[0108] In one embodiment, the second pattern 24 may have a length greater than that of the first pattern 22. For example, this length may be measured as the length of the longest portion of either the first pattern 22 or the second pattern 24.

[0109] For example, the first pattern 22 may have a length of less than or equal to 0.5 μm, while the second pattern 24 may have a length of greater than or equal to 1.0 μm. In one embodiment, the length of the second pattern 24 is less than or equal to 7.0 μm.

[0110] In one embodiment, coating 20 may simultaneously include a first pattern 22 and a second pattern 24. Therefore, lithium-ion isolation in the region surrounded by the chain pattern can be prevented, as well as electronic isolation within the island pattern. This improves both the ionic and electronic conductivity of the electrode active material 50.

[0111] In some embodiments, coating 20 may include a third pattern 26 having a mesh-like shape. The mesh-like shape may refer to a mesh structure formed by a plurality of interconnected chain-like shapes. For example, at least two second patterns 24 may intersect and connect to form the third pattern 26.

[0112] Because the conductive coating includes a third pattern 26 with a mesh shape, an additional continuous electron migration path through the third pattern 26 can be provided on the surface of the core particle 10. Accordingly, the electronic conductivity of the positive electrode active material 50 can be further improved, and the output characteristics of the lithium secondary battery can be further enhanced.

[0113] Furthermore, the third pattern 26 can further improve the contact between the core particles 10 and the solid electrolyte. For example, during the mixing of the electrode active material 50 and the solid electrolyte, the solid electrolyte can be entangled or trapped by the mesh-like third pattern 26. Therefore, the solid electrolyte can contact or adhere to the surface of the core particles 10, thereby further promoting ion transport between the electrode active material and the solid electrolyte.

[0114] In some implementations, the median particle size (D) of the core particle 10 50 The core particle size can range from 1 μm to 20 μm. Within this range, side reactions between the core particles and the electrolyte can be suppressed, and the migration distance of lithium ions can be shortened, thereby further improving the capacity and output characteristics of lithium secondary batteries.

[0115] In one embodiment, the median particle size of the core particle 10 can be 2 μm to 18 μm, 3 μm to 17 μm, 4 μm to 15 μm, or 5 μm to 12 μm.

[0116] In some implementations, the electrode active material can be a positive electrode active material. For example, the electrode of a lithium secondary battery can be configured as a positive electrode.

[0117] In one embodiment, the core particle 10 may comprise lithium metal oxide particles.

[0118] For example, the core particle 10 may contain one or more compounds selected from lithium iron phosphate compounds, lithium cobalt oxides, lithium manganese oxides, lithium nickel oxides, or lithium complex oxides.

[0119] In one embodiment, the core particle 10 may comprise a compound represented by the following formula 2.

[0120] [Equation 2]

[0121] Li a Ni b M 1-b O2

[0122] In Equation 2, a and b can satisfy 0.95≤a≤1.08 and b≥0.5, and M can contain at least one element selected from Na, Mg, Ca, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Co, Fe, Cu, Ag, Zn, B, Al, Ga, C, Si, Sn, Ba and Sr.

[0123] In one embodiment, the core particle 10 comprises nickel (Ni) and may further comprise at least one of cobalt (Co) and manganese (Mn). For example, nickel-cobalt-manganese (NCM) based lithium oxide can be used as a positive electrode active material.

[0124] For example, nickel (Ni) can be provided as a metal related to the capacity of lithium-ion batteries. The higher the nickel content, the greater the increase in capacity and output of the lithium-ion battery. However, if the nickel content is too high, the cycle life of the lithium-ion battery will be shortened, and it may be detrimental in terms of mechanical and electrical stability.

[0125] In one embodiment, cobalt (Co) may be a metal associated with the conductivity or resistance of the lithium secondary battery. In one embodiment, M includes manganese (Mn), and Mn may be provided as a metal associated with the mechanical and electrical stability of the lithium secondary battery.

[0126] The chemical structure represented by Equation 2 illustrates the bonding relationships between elements contained in the lattice or crystal structure of the core particle 10, without excluding other additional elements. For example, M may be provided as the main active element of the core particle 10. It should be understood here that Equation 2 is provided to represent the bonding relationships between the main active elements, and that Equation 2 includes the introduction and substitution of additional elements.

[0127] In one embodiment, the core particle 10 may further include auxiliary elements added to the primary active element to enhance its chemical stability or crystal structure. The auxiliary elements may be incorporated into the crystal structure to form bonds, and it should be understood that this also applies to the chemical structure represented by Formula 2.

[0128] In some implementations, the electrode active material can be a negative electrode active material. For example, the electrode of a lithium secondary battery can be set as the negative electrode.

[0129] For example, carbon-based materials, such as crystalline carbon, amorphous carbon, carbon composites or carbon fibers, lithium alloys, silicon-based or tin-based materials, can be used as core particles 10.

[0130] Examples of amorphous carbon may include hard carbon, coke, mesocarbon microbeads (MCMB) calcined at temperatures below 1500 °C, mesophase pitch-based carbon fiber (MPCF), and the like.

[0131] Examples of crystalline carbon may include graphite-based carbon, such as natural graphite, graphite cokes, graphite MCMB, graphite MPCF, and the like.

[0132] Other elements included in the lithium alloy may include, for example, aluminum, zinc, bismuth, cadmium, antimony, silicon, lead, tin, gallium, indium, and the like.

[0133] Silicon-based materials may include, for example, silicon (Si), SiO x (0 < x < 2), silicon / carbon (Si / C), silicon monoxide / carbon (SiO / C), silicon-metal, and the like.

[0134] In some embodiments, based on the total weight of the electrode active material layer, the content of the electrode active material may be 60 wt% to 99 wt%, 65 wt% to 97 wt%, 70 wt% to 95 wt%, 70 wt% to 90 wt%, 71 wt% to 88 wt%, or 72 wt% to 85 wt%.

[0135] Within the above range, the energy density and capacity characteristics of the lithium secondary battery can be further improved.

[0136] According to an exemplary embodiment, the electrode active material layer may further include a binder.

[0137] Binders may include polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene), polyacrylonitrile, polymethyl methacrylate, acrylonitrile butadiene rubber, polybutadiene rubber, styrene-butadiene rubber (SBR), and the like.

[0138] In one embodiment, a PVDF-based binder can be used as the binder for the positive electrode. In one embodiment, acrylonitrile butadiene rubber, polybutadiene rubber, or styrene-butadiene rubber can be used as the binder for the negative electrode, and a thickening agent such as carboxymethyl cellulose (CMC) may further be included.

[0139] In some embodiments, the binder content can be 0.5% to 5% by weight, 1.0% to 4.0% by weight, or 1.0% to 3.0% by weight, based on the total weight of the electrode active material layer. Within these ranges, the stability, adhesion, and energy density of the electrode active material layer can be further improved, while reducing internal resistance.

[0140] Figure 2 This is a flowchart illustrating a method for manufacturing a lithium secondary battery electrode according to an exemplary embodiment. Reference will be made below. Figure 2 A method for manufacturing electrodes for lithium secondary batteries is described.

[0141] refer to Figure 2 Conductive particles can be coated onto the core particles to prepare electrode active materials (e.g., step S10).

[0142] For example, core particles and conductive particles can be mixed. Thermal, physical, or chemical forces are applied to the mixture of core particles and conductive particles to cause the conductive particles to adhere to the surface of the core particles.

[0143] In some implementations, conductive particles may be partially attached to the surface of the core particle. For example, a coating may be formed on a portion of the surface of the core particle.

[0144] In one implementation, a resonance mixer can be used to mix the core particles and conductive particles. An acoustic mixer can also be used as a resonance mixer. For example, an acoustic resonance mixer could be Resodyn's LabRAM series.

[0145] When the core particles and conductive particles are stirred using an acoustic resonance mixer, the powerful shear and impact forces generated by acoustic and vibrational energy can act on the particles, thereby causing the conductive particles to adhere to the surface of the core particles.

[0146] For example, during the mixing process in an acoustic resonance mixer, some conductive particles may aggregate to form island-like coatings, or some conductive particles may connect to form chain-like or mesh-like coatings.

[0147] In some implementations, the mixture can be stirred at a frequency of 58 Hz to 62 Hz. Within this range, conductive particles can partially cover the core particles and form a mesh pattern on the surface of the core particles.

[0148] For example, if the frequency of the acoustic resonator mixer is below 58 Hz, conductive particles may completely cover the surface of the core particles. If the frequency of the acoustic resonator mixer is above 62 Hz, the core particles may break and may not be able to form a chain-like or mesh-like coating.

[0149] In some embodiments, the mixture can be stirred at an acceleration greater than 40 G and less than 75 G. Within this range, the shape, coverage, and thickness of the coating can be appropriately adjusted.

[0150] In some embodiments, the mixing time of the mixture can be from 1 minute to 50 minutes, 5 minutes to 40 minutes, or 10 minutes to 30 minutes. Within these ranges, the conductive particles can partially adhere to the surface of the core particles, thereby facilitating the formation of a coating with a mesh-like structure.

[0151] In one embodiment, the conductive particles may include dot-shaped conductive material. By using dot-shaped conductive material as conductive particles, coatings with island-like, chain-like, or mesh-like shapes can be easily formed.

[0152] The electrode active material can be mixed with a solid electrolyte (e.g., step S20).

[0153] For example, a solid electrolyte can be added to the electrode active material and stirred.

[0154] In one embodiment, the electrode active material may include a mesh coating in which the solid electrolyte can be entangled during mixing with the electrode active material. This can suppress aggregation between solid electrolytes and further improve the dispersibility of the solid electrolyte.

[0155] In one embodiment, mixing and stirring can be carried out under wet conditions. For example, electrode active materials and solid electrolytes can be mixed and stirred in a solvent.

[0156] The mixture of electrode active material and solid electrolyte can be mixed with fibrous conductive material to prepare electrode slurry (e.g., step S30).

[0157] Fibrous conductive materials can be added to the mixture so that the ratio of conductive particles to fibrous conductive materials is 0.01 to 2.0 (based on the total weight of the electrode paste).

[0158] In one embodiment, the fibrous conductive material can be added to the mixture at the aforementioned amount and stirred to ensure uniform dispersion in the mixture. By first mixing the coated core particles with the solid electrolyte and then mixing the fibrous conductive material, the dispersibility of the electrode active material, the solid electrolyte, and the fibrous conductive material can be improved.

[0159] For example, since the solid electrolyte is wrapped in the coating and fixed on the surface of the electrode active material, the electrode active material and the solid electrolyte can be uniformly dispersed in the mixture even after being mixed with the fibrous conductive material.

[0160] Furthermore, since the amount of fibrous conductive material can be reduced due to the conductive coating, aggregation between the fibrous conductive materials can be suppressed. Accordingly, a uniform electronic conductive network can be formed in the electrode active material layer, and the solid electrolyte can provide sufficient ion transport channels.

[0161] In some implementations, an additional binder may be added to the electrode slurry. For example, a binder solution may be added to a mixture of electrode active material, solid electrolyte, and fibrous conductive material, and then stirred.

[0162] In one embodiment, the electrode slurry may also contain a dispersant. For example, the dispersant may be added together with the binder solution.

[0163] Electrode slurry can be coated onto the electrode current collector to form an electrode active material layer (e.g., step S40).

[0164] For example, an electrode slurry can be coated onto at least one surface of an electrode current collector, and then dried and rolled to manufacture an electrode for a lithium secondary battery.

[0165] According to embodiments of this application, a lithium secondary battery may include the electrodes described above for a lithium secondary battery. The lithium secondary battery may include the electrodes for a lithium secondary battery and a counter electrode disposed opposite to the electrodes for a lithium secondary battery.

[0166] In some embodiments, the electrode for the lithium secondary battery may be provided as the positive electrode. In some embodiments, the electrode for the lithium secondary battery may be provided as the negative electrode. In some embodiments, both the positive and negative electrodes may include electrodes for the lithium secondary battery.

[0167] Figure 3 and Figure 4 These are schematic plan views and schematic cross-sectional views of a lithium secondary battery according to an exemplary embodiment. Figure 4 It is along Figure 3 The cross-sectional view taken from I-I' in the image.

[0168] refer to Figure 3 and Figure 4 The lithium secondary battery may include a positive electrode 100 and a negative electrode 130 disposed opposite to the positive electrode 100.

[0169] The positive electrode 100 may include a positive electrode current collector 105 and a positive electrode active material layer 110 formed on at least one surface of the positive electrode current collector 105. In one embodiment, the positive electrode active material layer 110 may be formed on two surfaces (e.g., an upper surface and a lower surface) of the positive electrode current collector 105.

[0170] The positive electrode active material layer 110 may include the aforementioned positive electrode active material, solid electrolyte, conductive material and / or adhesive.

[0171] The positive current collector 105 may include stainless steel, nickel, aluminum, titanium, or alloys thereof. The positive current collector 105 may also include aluminum or stainless steel with a surface treated with carbon, nickel, titanium, or silver.

[0172] The negative electrode 130 may include a negative electrode current collector 125 and a negative electrode active material layer 120 formed on at least one surface of the negative electrode current collector 125. In one embodiment, the negative electrode active material layer 120 may be formed on both surfaces (e.g., an upper surface and a lower surface) of the negative electrode current collector 125.

[0173] The negative electrode active material layer 120 may include the aforementioned negative electrode active material, solid electrolyte, conductive material, binder and / or dispersant.

[0174] The negative electrode current collector 125 may include gold, stainless steel, nickel, aluminum, titanium, copper, or alloys thereof. For example, the negative electrode current collector 125 may include copper or a copper alloy.

[0175] In some embodiments, a separator 140 may be inserted between the positive electrode 100 and the negative electrode 130. The separator 140 may comprise a porous polymer membrane made of a polyolefin polymer (e.g., ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, ethylene / methacrylate copolymer). The separator may also comprise a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc.

[0176] According to an exemplary embodiment, the positive electrode 100, the negative electrode 130, and the separator 140 can be repeatedly configured to form an electrode assembly 150. In some embodiments, the electrode assembly 150 may be a wound type, a stacked type, a z-folding type, or a stack-folding type.

[0177] The electrode assembly 150 can be housed in the housing 160 to define the lithium secondary battery.

[0178] According to an exemplary embodiment, the electrode assembly 150 may be housed together with an electrolyte within a housing 160. The electrolyte may be a non-aqueous electrolyte.

[0179] Non-aqueous electrolytes may include lithium salts of the electrolyte and organic solvents. Lithium salts are, for example, made from Li... + X - This indicates that the anion (X) of the lithium salt... - Examples of F can be given. - Cl - ,Br - I - NO3 - N(CN)2 - BF4 - ClO4 - PF6 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - CF3CF2SO3 - (CF3SO2)2N - (FSO2)2N - CF3CF2(CF3)2CO - ,

[0180] (CF3SO2)2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - wait.

[0181] As organic solvents, for example, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, dipropyl carbonate, dimethyl sulfuroxide, acetonitrile, dimethoxyethane, diethoxyethane, vinylene carbonate, sulfolane, γ-butyrolactone, propylene sulfite, and tetrahydrofuran can be used. These solvents can be used alone or in combination of two or more.

[0182] In some embodiments, a solid electrolyte layer may be inserted between the positive electrode 100 and the negative electrode 130. The solid electrolyte layer may include a sulfide-based electrolyte, an oxide-based electrolyte, or a polymer electrolyte.

[0183] In this configuration, the lithium secondary battery may not require a separator and electrolyte. The solid electrolyte layer essentially functions as a separator, preventing short circuits between the positive and negative electrodes. Furthermore, lithium ions can migrate between the positive and negative electrodes through the solid electrolyte layer.

[0184] like Figure 3 As shown, electrode tabs (positive and negative tabs) can extend from the positive current collector 105 and negative current collector 125 belonging to each electrode unit, respectively, and can extend to one side of the housing 160. The electrode tabs can be fused to one side of the housing 160 to form electrode leads (positive lead 107 and negative lead 127) extending to or exposed outside the housing 160.

[0185] Lithium secondary batteries can be made in shapes such as cylindrical (canister), prismatic, pouch, and coin.

[0186] The embodiments of this application will be further described below through specific experimental examples. The examples and comparative examples included in the experimental examples are only for illustrating this application and do not limit the scope of the appended claims. Those skilled in the art will understand that various changes and modifications can be made to the embodiments within the scope and technical concept of this application, and these changes and modifications naturally also fall within the scope of the appended claims.

[0187] Preparation Example

[0188] Example 1

[0189] (1) Preparation of positive electrode active material

[0190] 100 parts by weight of LiNi as the core particle 0.6 Co 0.2 Mn 0.2 O2(D 50 : 10μm) and 0.6 parts by weight of acetylene black (D) as conductive particles 50 (25nm to 30nm) was added to an acoustic resonance mixer (LabRAMⅡ, Resodyn). The frequency of the acoustic resonance mixer was set to 60Hz and the acceleration to 60G. Then, it was stirred for 20 minutes. Afterward, the positive electrode active material was obtained from the acoustic resonance mixer.

[0191] (2) Preparation of the positive electrode

[0192] The positive electrode active material consists of 75 parts by weight, Li6PS5Cl as a solid electrolyte, and carbon nanotubes (specific surface area: 175 m²) as a conductive material. 2The positive electrode slurry was prepared by mixing 2 parts by weight of polyvinylidene fluoride (PVDF) as a binder with (g, diameter: 10nm to 15nm).

[0193] The positive electrode slurry was uniformly coated onto an aluminum foil with a thickness of 15 μm, and then vacuum dried and rolled to form a positive electrode active material layer with a density of 3.2 g / cc, thereby preparing the positive electrode.

[0194] (3) Manufacturing of lithium secondary batteries

[0195] A negative electrode slurry was prepared by mixing artificial graphite (as the negative electrode active material), carbon nanotubes (CNTs) (as the conductive material), and styrene-butadiene rubber (SBR) (as the binder) in a weight ratio of 92:5:3. The negative electrode slurry was coated onto a copper foil with a thickness of 15 μm, and then dried and rolled to prepare the negative electrode.

[0196] Li6PS5Cl, used as a solid electrolyte, and SBR, used as a binder, were mixed at a weight ratio of 97:3 to prepare a slurry. The slurry was then coated onto a release film, dried, and rolled to prepare a solid electrolyte sheet.

[0197] Solid electrolyte sheets are cut into 3cm × 4cm dimensions, and positive and negative electrodes are stacked on the two surfaces of the solid electrolyte sheets to form an electrode assembly. Subsequently, the tabs of the positive and negative electrodes are soldered separately, and the electrode assembly, including the soldered positive / solid electrolyte / negative electrodes, is placed in a pouch and vacuum-sealed to manufacture a lithium secondary battery.

[0198] Example 2-21

[0199] The lithium secondary battery was manufactured using the same method as in Example 1, except that the input amounts of acetylene black and carbon nanotubes were varied according to Table 1 below, and the content of the solid electrolyte was adjusted so that the total weight of the positive electrode slurry was 100 parts by weight.

[0200] Example 22

[0201] The lithium secondary battery was manufactured using the same method as in Example 1, except that carbon nanotubes (diameter: 12.5 nm, specific surface area: 175 m²) were used in the preparation of the positive electrode active material. 2 / g), instead of acetylene black, as conductive particles.

[0202] Comparative Example 1

[0203] A lithium secondary battery was manufactured using the same method as in Example 1, except that core particles without a conductive coating were used as the positive electrode active material.

[0204] Comparative Example 2

[0205] The lithium secondary battery was manufactured using the same method as in Example 8, except that core particles without a conductive coating were used as the positive electrode active material.

[0206] Comparative Example 3

[0207] The lithium secondary battery was manufactured using the same method as in Example 14, except that core particles without a conductive coating were used as the positive electrode active material.

[0208] Comparative Examples 4-6

[0209] The lithium secondary battery was manufactured using the same method as in Example 1, except that the amounts of acetylene black and carbon nanotubes were varied according to Table 1 below, and the content of the solid electrolyte was adjusted so that the total weight of the positive electrode slurry was 100 parts by weight.

[0210] Comparative Example 7

[0211] The lithium secondary battery was manufactured using the same method as in Example 1, except that acetylene black (D) was used in the preparation of the positive electrode active material. 50 Diameter: 25nm to 30nm), rather than carbon nanotubes, as a conductive material.

[0212] Comparative Example 8

[0213] A lithium-ion secondary battery was manufactured using the same method as Comparative Example 7, except that carbon nanotubes (diameter: 12.5 nm, specific surface area: 175 m²) were used in the preparation of the positive electrode active material. 2 / g), instead of acetylene black, as conductive particles.

[0214] [Table 1]

[0215]

[0216] Experimental Example

[0217] (1) Measurement of cross-sectional images of the positive electrode active material layer

[0218] Figure 5 and Figure 6 The images are scanning electron microscope (SEM) images of the positive electrode active material layers prepared in Example 1 and Comparative Example 1, respectively.

[0219] refer to Figure 5 A mesh coating is formed on the surface of the core particles, and the positive electrode active material and solid electrolyte are evenly distributed in the positive electrode active material layer.

[0220] refer to Figure 6 Because no coating is formed on the core particles, the dispersibility of the solid electrolyte is reduced, and the solid electrolyte is observed to be in an agglomerated state in a local area of ​​the positive electrode active material layer.

[0221] (2) Initial efficiency assessment

[0222] The manufactured compression cells were charged (CC-CV 0.1C-2C, 4.27V cutoff, where the cutoff current was 0.314mA at a charge rate of 0.1C, 0.627mA at a charge rate of 0.2C, 1.568mA at a charge rate of 0.5C, and 6.272mA at a charge rate of 2.0C) and discharged (CC 0.1C-2C, 2.5V cutoff) at 30°C to measure their initial charge and discharge capacities. The initial efficiency was evaluated as the percentage of the initial discharge capacity (A2) to the initial charge capacity (A1), as shown in Equation 1 below.

[0223] [Formula 1]

[0224] Initial efficiency (%) = A2 / A1 × 100

[0225] The evaluation results are shown in Table 2 below.

[0226] (3) Evaluation of high-rate characteristics

[0227] The manufactured compressed battery was charged and discharged at 0.1C for the first three cycles at 30°C, with a charge cut-off condition of 4.27V and a discharge cut-off condition of 2.5V, and the discharge capacity of the first cycle (B1) was measured. Subsequently, three charge-discharge cycles were performed at a rate of 0.2C, followed by three additional charge-discharge cycles at a rate of 0.5C. Finally, the battery was charged and discharged at a rate of 2.0C, and the discharge capacity (B2) was measured.

[0228] The high-rate characteristic is evaluated by calculating the percentage of discharge capacity (B2) at high rate (2.0C) relative to discharge capacity (B1) at low rate (0.1C), as shown in Equation 2 below.

[0229] [Equation 2]

[0230] High magnification characteristic (%) = B2 / B1 × 100

[0231] [Table 2]

[0232] Initial efficiency characteristics (%) High-rate characteristics (%) Example 1 90 85 Example 2 91 84 Example 3 90 87 Example 4 83 73 Example 5 87 74 Example 6 87 70 Example 7 87 68 Example 8 87 83 Example 9 88 84 Example 10 72 68 Example 11 77 65 Example 12 78 63 Example 13 79 61 Example 14 91 85 Example 15 88 71 Example 16 88 68 Example 17 87 65 Example 18 78 64 Example 19 75 62 Example 20 67 64 Example 21 85 61 Example 22 85 75 Comparative Example 1 63 48 Comparative Example 2 68 55 Comparative Example 3 50 29 Comparative Example 4 50 37 Comparative Example 5 54 41 Comparative Example 6 48 27 Comparative Example 7 65 55 Comparative Example 8 65 53

[0233] The evaluation results are shown in Table 2.

[0234] Referring to Tables 1 and 2, in the lithium secondary batteries of the examples, the content ratios of conductive particles and fibrous conductive materials are both within the target range, thus improving both initial efficiency and high-rate performance. In Comparative Examples 1-3, since the positive electrode active material does not contain a conductive coating, both initial efficiency and high-rate performance are significantly reduced.

[0235] In Comparative Examples 4-6, the ratio of conductive particle content to fibrous conductive material content was greater than 2.0, resulting in a decrease in both initial efficiency and high-rate performance.

[0236] In Comparative Examples 7 and 8, dot-shaped conductive materials were used instead of fibrous conductive materials as the conductive materials for the positive electrode active material layer. Compared with Example 1, the initial efficiency and high-rate characteristics were reduced.

[0237] [Explanation of reference numerals in the attached figures]

[0238] 10: Core Particles

[0239] 20: Coating

[0240] 22: First Pattern

[0241] 24: Second Pattern

[0242] 26: Third Pattern

[0243] 50: Electrode active material

[0244] 100: Positive electrode

[0245] 105: Positive current collector

[0246] 107: Positive lead

[0247] 110: Positive electrode active material layer

[0248] 120: Negative electrode active material layer

[0249] 125: Negative electrode current collector

[0250] 127: Negative lead

[0251] 130: Negative electrode

[0252] 140: Diaphragm

[0253] 150: Electrode assembly

[0254] 160: Outer shell

Claims

1. An electrode for a lithium secondary battery, comprising an electrode active material layer, said electrode active material layer comprising: An electrode active material comprising core particles and a coating covering at least a portion of the surface of the core particles and comprising conductive particles; Solid electrolytes; as well as fibrous conductive materials Wherein, based on the total weight of the electrode active material layer, the ratio of the content of the conductive particles to the content of the fibrous conductive material is 0.01 to 2.

0.

2. The electrode for a lithium secondary battery according to claim 1, wherein the conductive particles comprise a dot-shaped conductive material.

3. The electrode for a lithium secondary battery according to claim 1, wherein, Based on the total weight of the electrode active material layer, the content of the fibrous conductive material is from 0.5% to 2.5% by weight.

4. The electrode for a lithium secondary battery according to claim 1, wherein, The coating content is 0.1 to 3 parts by weight based on 100 parts by weight of core particles.

5. The electrode for a lithium secondary battery according to claim 1, wherein the specific surface area of ​​the fibrous conductive material is 0.1 m². 2 / g to 3000m 2 / g.

6. The electrode for a lithium secondary battery according to claim 1, wherein the diameter of the fibrous conductive material is from 0.4 nm to 400 nm.

7. The electrode for a lithium secondary battery according to claim 1, wherein, The ratio of the content of the conductive particles to the content of the fibrous conductive material is 0.1 to 1.

0.

8. The electrode for a lithium secondary battery according to claim 1, wherein the coating partially covers the surface of the core particle.

9. The electrode for a lithium secondary battery according to claim 1, wherein the coating comprises a third pattern having a mesh shape.

10. The electrode for a lithium secondary battery according to claim 9, wherein the coating further comprises a pattern having an island shape or a pattern having a chain shape.

11. The electrode for a lithium secondary battery according to claim 1, wherein, The median particle size (D) of the core particles 50 The range is from 1μm to 20μm.

12. The electrode for a lithium secondary battery according to claim 1, wherein, The electrode active material layer also includes a binder.

13. A method for manufacturing an electrode for a lithium secondary battery, comprising: A coating containing conductive particles is formed on the core particles to prepare electrode active materials; The electrode active material is mixed with a solid electrolyte; The mixture of the electrode active material and the solid electrolyte is mixed with a fibrous conductive material to form an electrode slurry; and The electrode slurry is coated onto the electrode current collector to form an electrode active material layer. Wherein, based on the total weight of the electrode slurry, the ratio of the content of the conductive particles to the content of the fibrous conductive material is 0.01 to 2.

0.

14. The method of manufacturing an electrode for a lithium secondary battery according to claim 13, wherein the conductive particles comprise a dot-shaped conductive material.

15. The method for manufacturing an electrode for a lithium secondary battery according to claim 13, wherein, The coating is partially formed on the core particles.

16. The method of manufacturing an electrode for a lithium secondary battery according to claim 13, wherein the coating comprises a mesh pattern formed of conductive particles continuously connected to each other.

17. The method for manufacturing an electrode for a lithium secondary battery according to claim 16, wherein, In the step of mixing the electrode active material with the solid electrolyte, the solid electrolyte is wound in a mesh pattern and in contact with the surface of the core particles.

18. The method of manufacturing an electrode for a lithium secondary battery according to claim 13, further comprising adding a binder to the electrode slurry.

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