Electrode, electrode assembly, and secondary battery including the same

Abstract

The present invention relates to an electrode for a secondary battery and an electrode assembly including the same, the electrode comprising a composite layer and a gas adsorption layer formed on at least one surface of an electrode collector, and the composite layer has a pattern structure, and the gas adsorption layer is provided in a non-patterned region of the composite layer. This provides an excellent effect in removing gas generated during initial charging and discharging of the secondary battery, and thus provides the advantage that the performance and stability of the secondary battery including the electrode assembly is excellent.

Description

[Technical Field]

[0001] The present invention relates to an electrode for a secondary battery that includes a means for adsorbing gases generated during charging and discharging.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0138184, dated October 18, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference. [Background technology]

[0003] Recently, with the increasing technological development and demand for mobile devices and the popularization of electric vehicles (EVs), the demand for batteries as an energy source has increased dramatically, resulting in a great deal of research being conducted on batteries that can meet various needs.

[0004] Typically, from the viewpoint of battery shape, there is a high demand for prismatic secondary batteries and pouch-type secondary batteries that are thin and applicable to products such as mobile phones, and from the viewpoint of materials, there is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries that have advantages such as high energy density, discharge voltage, and output stability.

[0005] However, despite these advantages, lithium secondary batteries have safety drawbacks. Specifically, immediately after the electrolyte is injected into the battery assembly, gas is generated due to the reaction of the electrolyte during primary charging, aging, and charge / discharge. This gas is trapped inside the battery, causing problems such as reduced capacity and lithium deposition. Furthermore, if an abnormal operating condition occurs after the final sealing, such as an internal short circuit, overcharging, or exposure to high temperatures, the electrolyte decomposes, generating a considerable amount of gas, which can increase internal pressure. The high-pressure gas generated at this time can cause deformation of the battery case, shorten the battery's lifespan, and in severe cases, lead to battery fire or explosion.

[0006] To solve this problem, a degassing process has been used in the past to exhaust gas generated in secondary batteries by using a vacuum during the manufacture of secondary batteries. However, this process also causes electrolyte to leak out, resulting in problems such as an increase in the defect rate of lithium batteries and a decrease in the uniformity of the lifespan of secondary batteries.

[0007] In addition, to capture the generated gas, a gas pocket is formed in the exterior material of a pouch-type secondary battery to capture the generated gas during the activation process, and then holes are drilled in the gas pocket to remove the gas. The gas pocket is then cut and the pouch exterior material is resealed to meet the specifications of the final product. However, this method is very inefficient from a production perspective. Therefore, a new method is needed that can efficiently remove gas generated inside a battery during manufacturing without degrading the overall performance of the battery. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 10-2019-0142965 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a secondary battery that can remove gas generated during charging and discharging of the battery, particularly during activation. [Means for solving the problem]

[0010] To achieve the above objectives, In one embodiment, the present invention provides an electrode current collector; a composite layer and a gas adsorption layer formed on at least one surface of the electrode current collector, The composite layer has a pattern structure, and a gas adsorption layer is provided in the non-patterned region of the composite layer to provide an electrode for a secondary battery.

[0011] At this time, the composite layer and the gas adsorption layer can form a single layer with no irregularities on the surface.

[0012] For this reason, the average thickness of the composite layer may be equal to or greater than the average thickness of the gas adsorption layer.

[0013] The average thickness of the composite layer and the average thickness of the gas adsorption layer may each be 0.01 to 5 mm.

[0014] The area of the gas adsorption layer can occupy 5 to 30% of the area of the composite layer.

[0015] The gas adsorption layer may contain one or more gas adsorbents selected from the group consisting of porous carbon materials, porous metal oxides, and porous gels.

[0016] Here, the porous carbon material may contain one or more materials selected from the group consisting of carbon fiber, carbon molecular sieve, and activated carbon.

[0017] The porous metal oxide may also contain one or more elements selected from the group consisting of nickel (Ni), platinum (Pt), palladium (Pd), calcium (Ca), strontium (Sr), barium (Ba), thallium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), and tungsten (W).

[0018] In one embodiment, the present invention provides: a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; the positive electrode and the negative electrode each include a composite layer and a gas adsorption layer formed on at least one surface of a current collector, the composite layer having a pattern structure on the current collector, and the gas adsorption layer being provided in a non-patterned region of the composite layer; The positive electrode gas adsorption layer and the negative electrode gas adsorption layer are disposed to abut on each other with respect to the separator to provide an electrode assembly.

[0019] Here, the positive electrode and the negative electrode may have a structure in which a composite layer and a gas adsorption layer are formed on both sides of each current collector; or a structure in which a composite layer is formed on one side of each current collector and a composite layer and a gas adsorption layer are formed on the other side.

[0020] Furthermore, in one embodiment, the present invention provides a secondary battery including the electrode assembly according to the present invention. [Effects of the Invention]

[0021] The electrode for a secondary battery according to the present invention has a patterned composite layer formed on an electrode current collector, and a gas adsorption layer formed in the non-patterned region of the composite layer, thereby providing an excellent effect of removing gas generated during the initial charge and discharge of the secondary battery, thereby providing an effect of improving the performance and stability of the secondary battery including the electrode. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a plan view showing an example of an electrode for a secondary battery including a gas adsorbent according to the present invention. [Figure 2] 1 is a cross-sectional view showing an example of an electrode for a secondary battery including a gas adsorbent according to the present invention. [Figure 3] 1 is a cross-sectional view illustrating an example of an electrode assembly for a secondary battery including a gas adsorbent according to the present invention. [Figure 4] 1 is a cross-sectional view illustrating an example of an electrode assembly for a secondary battery including a gas adsorbent according to the present invention. [Figure 5] 1 is a cross-sectional view illustrating an example of an electrode assembly for a secondary battery including a gas adsorbent according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to provide a detailed description of the present invention so that those skilled in the art can easily carry out the present invention. The objects, functions, effects, and other objects, features, and operational advantages of the present invention will become more apparent from the description of the preferred embodiments.

[0024] For reference, the embodiments disclosed herein have been presented by selecting the most preferred embodiments from among various possible examples to aid in the understanding of those skilled in the art, and the technical ideas of the present invention are not necessarily limited or restricted to only the presented embodiments, and various changes, additions, and modifications, including equivalents or substitutions, are possible within the scope that does not deviate from the technical ideas of the present invention.

[0025] Furthermore, the terms and expressions used in the specification and claims of this application are defined based on the principle that the inventor can appropriately define the concepts of the terms in order to best explain his / her invention, and should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that correspond to the technical ideas of the present invention. For example, singular expressions include plural expressions unless the context clearly dictates otherwise, and directional expressions are based on the positions depicted in the drawings for the convenience of explanation.

[0026] <Electrode for secondary batteries> In one embodiment, the present invention provides The present invention provides an electrode for a secondary battery, comprising an electrode current collector, and a composite layer and a gas adsorption layer formed on at least one surface of the electrode current collector, wherein the composite layer has a non-coated area by having a pattern structure or grooves formed on the electrode current collector, and the gas adsorption layer is formed in the non-coated area.

[0027] 1 and 2 are a plan view and a cross-sectional view, respectively, showing an example of an electrode 1 for a secondary battery according to the present invention.

[0028] Referring to Figures 1 and 2, an electrode 1 for a secondary battery according to the present invention may include a current collector 11, a composite layer 12, and a gas adsorption layer 13, and the electrode 1 may be a positive electrode or a negative electrode.

[0029] Here, the composite layer 12 may have a pattern structure on the current collector 11, and this is to form a gas adsorption layer 13 between the patterns of the composite layer 12, thereby immediately removing gas generated near the composite layer during charging and discharging of the battery, thereby suppressing side reactions between the active ingredients of the composite layer and the gas.

[0030] Furthermore, the pattern structure of the mixture layer 12 is not particularly limited as long as the gas adsorption layer 13 can occupy a certain area within the mixture layer 12 .

[0031] As an example, the composite layer 12 may have a striped pattern structure, in which case the width of the gas adsorption layer 13 may be 1 to 5 mm, or 2 to 4 mm.

[0032] Furthermore, the composite layer 12 can form a single layer together with the gas adsorption layer 13, with the surface being free of irregularities. That is, the secondary battery electrode 1 according to the present invention has a structure in which a single combined layer is provided on the electrode current collector 11, and the layer is formed by combining the composite layer 12 and the gas adsorption layer 13. By controlling the structure so that the composite layer 12 and the gas adsorption layer 13 form a single layer with no irregularities, the present invention can prevent reductions in the energy density of the electrode assembly and deterioration in workability during manufacturing, which are caused by electrode irregularities.

[0033] Furthermore, the composite layer 12 and the gas adsorption layer 13 form a single combined layer with no irregularities on the surface, and the average thickness thereof may be the same as or greater than the average thickness of the gas adsorption layer 13.

[0034] As an example, a layer formed by combining a composite layer 12 and a gas adsorption layer 13 may have a structure in which the composite layer 12 is present only in the patterned area and not in the non-patterned area, and the gas adsorption layer 13 completely fills the non-patterned area, as shown in FIG. 3, so that the average thickness of the composite layer 12 and the average thickness of the gas adsorption layer 13 may be the same.

[0035] As another example, a layer combined with a composite layer 12 and a gas adsorption layer 13 may have a structure in which the composite layer 12 has a relief pattern structure P on its surface, and the gas adsorption layer 13 is provided in the recessed (or grooved) NP, as shown in Figure 5, and the composite layer 12 has a patterned structure on its surface, so that the average thickness of the composite layer 12 is thicker than the average thickness of the gas adsorption layer 13.

[0036] The average thickness of the composite layer 12 and the gas adsorption layer 13 may each be 0.01 to 5 mm, specifically 0.01 to 3 mm, 0.01 to 2 mm, 0.01 to 1 mm, 0.05 to 1 mm, or 0.01 to 0.5 mm.

[0037] Furthermore, when observed on the surface of the secondary battery electrode, the area of gas adsorption layer 13 may be 5 to 30% of the area of composite layer 12, specifically 5 to 20%, 5 to 10%, 10 to 30%, 15 to 30%, or 20 to 30%.

[0038] As described above, the present invention can maximize the electrical performance of a secondary battery, more effectively remove gas generated during charging and discharging of the secondary battery, and prevent lithium metal (Li) from being precipitated due to uneven charging and discharging by adjusting the structure, average thickness, and / or area ratio of the composite layer and the gas adsorption layer.

[0039] The gas adsorbing layer 13 may contain one or more gas adsorbents selected from the group consisting of porous carbon materials, porous metal oxides, and porous gels, all of which have gas adsorption properties.

[0040] In this case, the porous carbon material may contain one or more members selected from the group consisting of carbon fiber, carbon molecular sieve, and activated carbon.

[0041] As an example, the porous carbon material may include activated carbon.

[0042] The porous metal oxide may also contain one or more elements selected from the group consisting of silicon (Si), aluminum (Al), nickel (Ni), platinum (Pt), palladium (Pd), calcium (Ca), strontium (Sr), barium (Ba), thallium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), and tungsten (W).

[0043] As an example, the porous metal oxide may contain silica particles containing silicon (Si); alumina containing aluminum (Al); or zeolite containing silicon (Si) and aluminum (Al), either alone or in combination. In some cases, the porous metal oxide may contain silica particles, alumina, and / or zeolite doped with nickel (Ni), vanadium (V), molybdenum (Mo), or the like.

[0044] Meanwhile, the current collector 11 is not particularly limited as long as it generally has a thickness of 3 to 500 μm, does not induce chemical changes in the battery, and has high conductivity. For example, stainless steel, aluminum, nickel, titanium, baked carbon, or aluminum or stainless steel whose surface has been treated with carbon, nickel, titanium, silver, or the like may be used. The current collector may have fine irregularities on its surface to increase the adhesive strength of the electrode active material, and may be in various forms such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0045] The mixture layer 12 is produced by applying a mixture of an active material, a conductive material, and a binder, followed by drying, and if necessary, adding a filler to the mixture.

[0046] When the electrode 1 is a positive electrode, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn 2-x Lithium manganese oxides such as LiMnO4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2Cu2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, and Cu2V2O7; and the chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by the chemical formula LiMnO2 (where M=Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x=0.01 to 0.3) 2-x M x Examples of suitable lithium manganese composite oxides include, but are not limited to, lithium manganese composite oxides represented by Li2Mn3MO8 (where M is Co, Ni, Fe, Cr, Zn, or Ta, and x is 0.01 to 0.1) or Li2Mn3MO8 (where M is Fe, Co, Ni, Cu, or Zn); LiMn2O4, in which part of the Li in the chemical formula is substituted with an alkaline earth metal ion; disulfide compounds; and Fe2(MoO4)3.

[0047] When the electrode 1 is a negative electrode, examples of the negative electrode active material include carbon such as non-graphitizable carbon and graphite-based carbon; x Fe2O3(0≦x≦1), Li x WO2(0≦x≦1), Sn x Me 1-x Me' y O zMetal composite oxides such as (Me: Mn, Fe, Pb, Ge, Me’: Al, B, P, Si, Group 1, Group 2, and Group 3 elements of the periodic table, halogens, 0 < x ≤ 1, 1 ≤ y ≤ 3, 1 ≤ z ≤ 8), lithium metal, lithium alloys, silicon-based alloys, tin-based alloys, metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5, conductive polymers such as polyacetylene, Li-Co-Ni-based materials, etc. may be used.

[0048] At this time, the above positive electrode active material and / or negative electrode active material may be contained at 80 to 98% by weight based on the total weight of the composite material layer.

[0049] Also, the above conductive material is usually added at 1 to 10% by weight based on the total weight of the mixture containing the active material and is applied to both the positive electrode and the negative electrode. Such a conductive material is not particularly limited as long as it has conductivity without inducing a chemical change in the battery. For example, graphite such as natural graphite and artificial graphite, carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc., conductive fibers such as carbon fibers and metal fibers, metal powders such as carbon fluoride, aluminum, nickel powder, etc. may be used.

[0050] Also, the above binder is a component that helps bind the active material and the conductive material, etc. and bind to the current collector. Usually, it is added at 1 to 10% by weight based on the total weight of the mixture containing the active material and is similarly applied to both the positive electrode and the negative electrode. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluorine rubber, various copolymers, etc.

[0051] The filler is selectively used as a component to suppress electrode expansion, and is not particularly limited as long as it is a fibrous material that does not induce chemical changes in the battery, and examples of such fibrous materials include olefin polymers such as polyethylene and polypropylene; glass fiber; and carbon fiber. Similarly, the filler can be applied to both the positive and negative electrodes.

[0052] In addition, other components such as a viscosity adjuster, an adhesion promoter, etc. may be further included selectively or in combination of two or more, and a detailed description thereof will be omitted.

[0053] <Electrode assembly for secondary batteries> In one embodiment, the present invention provides: a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; The positive electrode and the negative electrode include the secondary battery electrode of the present invention described above, The electrode assembly for a secondary battery includes gas adsorption layers formed on a positive electrode and a negative electrode, respectively, and arranged to abut against a separator.

[0054] The electrode assembly for a secondary battery according to the present invention includes the above-described secondary battery electrode of the present invention as a positive electrode and a negative electrode, and thus can effectively remove gas generated during charging and discharging of the secondary battery, particularly during activation, thereby providing the secondary battery with excellent electrical performance and safety.

[0055] FIG. 3 is a cross-sectional view of an electrode assembly for a secondary battery including a gas adsorbent according to one embodiment of the present invention.

[0056] The electrode assembly 10 includes a positive electrode 20, a negative electrode 30, and a separator 40.

[0057] The positive electrode 20 comprises a positive electrode current collector 210, a positive electrode composite layer 220, and a positive electrode gas adsorption layer 230. The negative electrode 30 comprises a negative electrode current collector 310, a negative electrode composite layer 320, and a negative electrode gas adsorption layer 330.

[0058] In the case of the positive electrode 20, the positive electrode composite layer 220 and the positive electrode gas adsorption layer 230 may be coated on both sides of the positive electrode current collector 210, and in the case of the negative electrode 30, similar to the positive electrode 20, the negative electrode composite layer 320 and the negative electrode gas adsorption layer 330 may be coated on both sides of the negative electrode current collector 310.

[0059] The pattern structure of the positive electrode composite layer 220 and the pattern structure of the negative electrode composite layer 320 adjacent to the separator 40 are preferably coated to completely overlap with respect to the separator 40, and the positive electrode gas adsorption layer 230 and the negative electrode gas adsorption layer 330 formed in the non-patterned regions of the composite layers 220 and 320 are preferably coated to completely overlap with respect to the separator 40. This is because, if the positive electrode composite layer 220 and the negative electrode composite layer 320 are not coated in the same position with respect to the separator 40, lithium deposition may occur due to non-uniform charging and discharging.

[0060] Furthermore, the outer positive electrode composite layer 221 coated on one side of the positive electrode current collector 210 and the inner positive electrode composite layer 222 coated on the other side are coated to overlap with each other based on the positive electrode current collector 210, and the outer negative electrode composite layer 321 coated on one side of the negative electrode current collector 310 and the inner negative electrode composite layer 322 coated on the other side are coated to overlap with each other based on the negative electrode current collector 310. As a result, the outer positive electrode gas adsorption layer 231, the inner positive electrode gas adsorption layer 232, the outer negative electrode gas adsorption layer 331, and the inner negative electrode gas adsorption layer 332 are all formed to overlap with each other, thereby preventing uneven charging and discharging and simplifying the manufacturing process.

[0061] FIG. 4 is a cross-sectional view of an electrode assembly for a secondary battery including a gas adsorbent according to yet another embodiment of the present invention.

[0062] 4, only the inner positive electrode composite layer 222' adjacent to the separator 40 relative to the positive electrode current collector 210 has a patterned structure, and the positive electrode gas adsorption layer 232' is formed in the non-patterned region of the positive electrode composite layer 222'. Alternatively, only the inner negative electrode composite layer 322' adjacent to the separator 40 relative to the negative electrode current collector 310 may have a patterned structure, and the negative electrode gas adsorption layer 332' may be formed in the non-patterned region of the negative electrode composite layer 322'. Alternatively, the patterned structure of the positive electrode composite layer 222' and the patterned structure of the negative electrode composite layer 322' may be formed to overlap with each other relative to the separator 40, and the positive electrode gas adsorption layer 232' and the negative electrode gas adsorption layer 332' may be formed to overlap with each other.

[0063] <Secondary battery> The present invention also provides a secondary battery including the above-described electrode assembly.

[0064] The secondary battery according to the present invention includes the electrode assembly of the present invention described above, and thus can effectively remove gas generated during charging and discharging, especially during activation, thereby providing the secondary battery with excellent electrical performance and safety.

[0065] Here, the secondary battery may be used as a power source for devices that require high-temperature safety, long cycle characteristics, and high rate characteristics. Specific examples of such devices include, but are not limited to, mobile electronic devices, wearable electronic devices, power tools powered by electric motors, electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), electric bicycles (E-bikes), electric two-wheeled vehicles including electric scooters, electric golf carts, and energy storage systems.

[0066] The present invention will be described in more detail below with reference to examples. However, the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

[0067] (Examples 1 and 2. Production of secondary batteries) A gas adsorption slurry was prepared by mixing silica particles and zeolite particles (Ni doped) in a ratio of 1:1.

[0068] Separately, N-methylpyrrolidone was poured into a homomixer, and LiNi as a positive electrode active material was added to 100 parts by weight of the positive electrode slurry solids. 0.6 Co 0.2 Mn 0.2 A positive electrode slurry for a lithium secondary battery was prepared by uniformly mixing 97.8 parts by weight of O2, 0.7 parts by weight of carbon black as a conductive material, and 1.5 parts by weight of PVDF as a binder. The prepared positive electrode slurry was applied to both sides of an aluminum thin plate in a striped pattern, and the gas adsorption slurry was applied to the non-patterned areas. The plate was then dried and rolled to prepare a positive electrode in which the composite layer and gas adsorption layer were formed into a single, smooth layer.

[0069] Separately, water was poured into a homomixer, and 100 parts by weight of the negative electrode slurry solids were mixed uniformly with 97.5 parts by weight of artificial graphite as the negative electrode active material, 2 parts by weight of styrene butadiene rubber (SBR) as a binder, and 0.5 parts by weight of carboxymethyl cellulose (CMC) as a thickener to prepare a negative electrode slurry for a lithium secondary battery. The prepared negative electrode slurry was applied to both sides of a copper sheet in a striped pattern similar to that of the positive electrode, and the gas adsorption slurry was applied to the non-patterned areas, followed by drying and rolling to prepare a negative electrode in which the composite layer and gas adsorption layer were formed into a single, smooth layer.

[0070] The thickness and structure of the composite layer and gas layer of the manufactured positive and negative electrodes are as shown in Table 1 below.

[0071] An electrode assembly was fabricated by interposing a porous polyethylene (PE) film (average thickness: 20 μm, length: 30 cm) as a separator between the fabricated positive and negative electrodes, and the fabricated electrode assembly was inserted into a cell pouch and an electrolyte was injected to fabricate a lithium secondary battery.

[0072] [Table 1]

[0073] (Comparative Example 1. Manufacture of secondary battery) A gas adsorption slurry was prepared by mixing silica particles and zeolite particles (Ni doped) in a ratio of 1:1.

[0074] Separately, N-methylpyrrolidone was poured into a homomixer, and LiNi as a positive electrode active material was added to 100 parts by weight of the positive electrode slurry solids. 0.6 Co 0.2 Mn 0.2 A positive electrode slurry for a lithium secondary battery was prepared by uniformly mixing 97.8 parts by weight of O2, 0.7 parts by weight of carbon black as a conductive material, and 1.5 parts by weight of PVDF as a binder. The prepared positive electrode slurry was applied to both sides of an aluminum thin plate, dried, and rolled to form a composite layer. The gas adsorption slurry was then applied successively to the composite layer, dried, and rolled to prepare a positive electrode with a gas adsorption layer formed on the composite layer.

[0075] Separately, water was poured into a homomixer, and 97.5 parts by weight of artificial graphite as the negative electrode active material, 2 parts by weight of styrene butadiene rubber (SBR) as a binder, and 0.5 parts by weight of carboxymethyl cellulose (CMC) as a thickener were uniformly mixed with 100 parts by weight of the negative electrode slurry solids to prepare a negative electrode slurry for a lithium secondary battery. The prepared negative electrode slurry was applied to both sides of a copper thin plate, dried, and rolled to form a composite layer. The gas adsorption slurry was then applied successively to the composite layer, dried, and rolled to prepare a positive electrode with a gas adsorption layer formed on the composite layer.

[0076] At this time, the average thicknesses of the positive electrode mixture layer, the negative electrode mixture layer, and the gas adsorption layers formed on each mixture layer were 0.5 mm, 0.5 mm, and 0.05 mm, respectively.

[0077] An electrode assembly was fabricated by placing a porous polyethylene (PE) film (average thickness: 20 μm, length: 30 cm) between the fabricated positive and negative electrodes as a separator. The fabricated electrode assembly was inserted into a cell pouch and an electrolyte was injected to fabricate a lithium secondary battery. The electrolyte was prepared by dissolving 1.0 M lithium hexafluorophosphate (LiPF6) in an organic solvent consisting of ethylene carbonate / dimethyl carbonate / ethyl methyl carbonate (EC / DMC / EMC mixture: 3 / 4 / 3 by volume).

[0078] (Experimental example) To evaluate the effects of the secondary battery electrodes according to the present invention, the secondary batteries fabricated in the examples and comparative examples were activated at 60°C with a constant current of 0.2 C until the secondary battery reached 60% state of charge (SOC), and gas generated during activation was removed. 0.1 cc of electrolyte was then extracted from the battery, and the content of gas dissolved in the electrolyte was analyzed by gas chromatography.

[0079] The activated and degassed secondary batteries were then charged and discharged 50 times at 45°C, 4.2V, and 0.33C. The electrolyte was extracted using the method described above, and the amount of gas dissolved in the electrolyte was analyzed during each charge and discharge. The results are shown in Table 2 below.

[0080] [Table 2]

[0081] As shown in Table 2 above, it was confirmed that the secondary battery according to the present invention has a composite layer having a patterned structure on a current collector and a gas adsorption layer provided in a non-patterned region of the composite layer, thereby significantly reducing the amount of gas generated during charge and discharge trapped inside the battery.

[0082] Although the present invention has been described above with reference to preferred embodiments, it will be understood that a person skilled in the art or with ordinary knowledge in the art can make various modifications and changes to the present invention without departing from the spirit and technical scope of the present invention as set forth in the claims.

[0083] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims. [Explanation of symbols]

[0084] 1 electrode 10 Electrode assembly 11 Current collector 12 Composite material layer 13 Gas adsorption layer 20 positive electrode 30 negative electrode 40 Separation membrane 210 Positive electrode current collector 310 Negative electrode current collector 220, 221, 222, 221', 222' Positive electrode composite layer 230, 231, 232, 232' cathode gas adsorption layer 320, 321, 322, 321', 322' Negative electrode composite layer 330, 331, 332, 332' Anode gas adsorption layer

Claims

1. an electrode current collector; a composite layer and a gas adsorption layer formed on at least one surface of the electrode current collector, the composite layer has a pattern structure, and a gas adsorption layer is provided in a non-pattern region of the composite layer; The gas adsorption layer has an average thickness of 0.3 to 0.5 mm.

2. The electrode for a secondary battery according to claim 1 , wherein the composite layer and the gas adsorption layer form a single layer having no irregularities on the surface.

3. The electrode for a secondary battery according to claim 1 , wherein the average thickness of the composite layer is equal to or greater than the average thickness of the gas adsorption layer.

4. 2. The electrode for a secondary battery according to claim 1, wherein the area of said gas adsorption layer is 5 to 30% of the area of said composite layer.

5. 2. The electrode for a secondary battery according to claim 1, wherein the gas adsorption layer contains one or more gas adsorbents selected from the group consisting of porous carbon materials, porous metal oxides, and porous gels.

6. 6. The electrode for a secondary battery according to claim 5, wherein the porous carbon material comprises at least one material selected from the group consisting of carbon fiber, carbon molecular sieve, and activated carbon.

7. 6. The electrode for a secondary battery according to claim 5, wherein the porous metal oxide contains one or more elements selected from the group consisting of nickel (Ni), platinum (Pt), palladium (Pd), calcium (Ca), strontium (Sr), barium (Ba), thallium (Tl), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), and tungsten (W).

8. a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; the positive electrode and the negative electrode each include a composite layer and a gas adsorption layer formed on at least one surface of a current collector, the composite layer having a pattern structure, the gas adsorption layer being provided in a non-patterned region of the composite layer, and the gas adsorption layer of the positive electrode and the gas adsorption layer of the negative electrode being arranged to abut on each other with the separation membrane as a reference.

9. A secondary battery comprising the electrode assembly according to claim 8.

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