KR20170055419A - Electrode for lithium secondary battery comprising hygroscopic materials and lithium secondary battery comprising the same - Google Patents

Abstract

The present invention relates to an electrode for a lithium secondary battery, wherein hygroscopic materials are located between pores formed by arranging active materials on an active material layer. The electrode for a lithium secondary battery of the present invention can remove moisture existing in the electrode and an electrolyte by locating the hygroscopic materials between the pores formed by the active materials on the active material layer, thereby removing side reactions by the presence of moisture inside the battery and improving the performance of the battery.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrode for a lithium secondary battery including a hygroscopic material, and a lithium secondary battery including the same. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to an electrode for a lithium secondary battery including a hygroscopic material and a lithium secondary battery including the same. More particularly, the present invention relates to an electrode for a lithium secondary battery including a hygroscopic material for removing minute moisture of the electrode, And a lithium secondary battery comprising the same.

As technology development and demand for mobile devices have increased, there has been a rapid increase in demand for secondary batteries as energy sources. Among such secondary batteries, lithium secondary batteries, which exhibit high energy density and operating potential, long cycle life, Batteries have been commercialized and widely used.

In recent years, there has been a growing interest in environmental issues, and as a result, electric vehicles (EVs) and hybrid electric vehicles (HEVs), which can replace fossil-fueled vehicles such as gasoline vehicles and diesel vehicles, And the like. Although a nickel metal hydride (Ni-MH) secondary battery is mainly used as a power source for such an electric vehicle (EV) and a hybrid electric vehicle (HEV), a lithium secondary battery having a high energy density, a high discharge voltage, Research is being actively carried out, and some are commercialized.

The lithium secondary battery has a structure in which a non-aqueous electrolyte containing a lithium salt is impregnated in an electrode assembly having a porous separator interposed between a positive electrode and a negative electrode coated with an active material on an electrode current collector.

Such a lithium secondary battery may cause degradation of the performance of the battery when moisture is contained therein. In the lithium secondary battery, moisture may be contained in the active material during the manufacturing process, or may be contained in a minute amount in the electrolytic solution. For example, lithium titanium oxide used as an anode active material is a zero-strain material having extremely low structural change during charging and discharging, has excellent lifetime characteristics, forms a relatively high voltage band, and has a dendrite And it is known that it has excellent safety and stability. Also, it has the advantage of having a rapid charging electrode characteristic that can be charged within a few minutes. However, due to the property of absorbing moisture in the air, There is a problem that the contained water is decomposed to generate a large amount of gas.

Further, the water present in the electrolyte solution reacts with the electrolytic solution due to the potential energy provided in the charging process, so that the reliability of the battery may deteriorate, such as a phenomenon in which the cell is swollen due to the generation of gas. For example, the LiPF ₆ lithium salt contained in the electrolyte reacts with water to form HF, which is a strong acid. The formed HF spontaneously reacts with the electrode active material exhibiting weak basicity to elute the electrode active material component, Further, lithium fluoride (LiF) is formed on the surface of the anode to increase the electrical resistance in the electrode, and gas is generated, resulting in deterioration of the life of the battery.

Accordingly, various methods have been used in order to remove moisture inside the lithium secondary battery. For example, in order to remove water from the electrode of the lithium secondary battery, moisture is removed from the electrode through a high-temperature drying process, A method of disposing a moisture absorptive material on a battery case or the like (Korean Patent Laid-Open Publication No. 2015-0037332) is used.

However, since the above method alone can not remove the moisture of the electrode to a desired degree, it is necessary to develop a new technology capable of improving the performance of the cell by more effectively removing the moisture of the electrode.

KR 2015-0037332 A

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above problems occurring in the prior art, and it is an object of the present invention to provide an electrode for a lithium secondary battery which can improve the performance of a battery by effectively removing water contained in the electrode and electrolyte of the lithium secondary battery.

It is another object of the present invention to provide a method of manufacturing an electrode for a lithium secondary battery including the hygroscopic material as described above.

According to one embodiment, the present invention provides an electrode for a lithium secondary battery comprising an active material layer and a current collector, wherein the active material layer includes an active material and a hygroscopic material, The electrode for a lithium secondary battery is provided.

According to another embodiment, the present invention provides a method of manufacturing a semiconductor device, comprising: (1) applying a slurry containing an active material on a current collector to form an active material layer; And (2) permeating the dispersion containing the hygroscopic material into the active material layer, so that the hygroscopic material is positioned between the voids in which the active material is arranged and formed .

The electrode for a lithium secondary battery according to the present invention can remove moisture present in the electrode and the electrolyte due to the presence of the hygroscopic material between the pores formed by the active material in the active material layer, , The performance of the battery can be improved.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram schematically showing a form in which an active material is arranged in an active material layer and a hygroscopic material is placed between pores formed therein;
2 is a diagram schematically showing a form in which the hygroscopic material is located on the surface of the active material.
3 is a diagram schematically showing a form in which the hygroscopic material is located between the active material and the current collector.
4 is a graph showing the results of measurement of the capacity retention rate of the batteries of Examples 1-1 to 20-1 and Comparative Examples 1-1 to 2-1, respectively, after 100 cycles.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

An electrode for a lithium secondary battery according to the present invention is an electrode for a lithium secondary battery comprising an active material layer and a current collector, wherein the active material layer includes an active material and a hygroscopic material, It is located between the pores.

The hygroscopic material may function to absorb and remove moisture contained in the battery, for example, moisture of the electrode and moisture of the electrolytic solution. Since the active material is arranged between the pores formed, the total volume of the active material layer is increased Thereby not causing the problem of reducing the energy density per unit volume.

The hygroscopic material is silica gel, _{zeolite, CaO, BaO, MgSO 4,} Mg (ClO 4) 2, MgO, P 2 O 5, Al 2 O 3, CaH 2, NaH, LiAlH 4, CaSO 4, Na 2 SO 4 At least one selected from the group consisting of CaCO ₃ , K ₂ CO ₃ , CaCl ₂ , 4A and 3A molecular sieve, Ba (ClO ₄ ) ₂ , crosslinked poly (acrylic acid) Specifically, it may be at least one selected from the group consisting of silica gel, zeolite, P ₂ O ₅ and Al ₂ O ₃ .

The active material may have an average particle diameter (D ₅₀ ) of 0.1 μm to 30 μm, specifically 0.5 μm to 10 μm, more specifically, an average particle diameter of 1 μm to 5 μm.

When the active material has an average particle diameter (D ₅₀ ) of 0.1 to 30 탆, the active material is arranged and the voids may have a size of 0.01 to 20 탆, specifically 0.03 to 10 탆, Lt; RTI ID = 0.0 > 5 < / RTI > At this time, the size of the cavity may be represented by the particle size of the sphere, assuming that the sphere is in contact with the cavity.

The hygroscopic material may have an average particle diameter (D ₅₀ ) of 10 nm to 20 μm so as to be included in the voids in which the active material is arranged, and specifically 30 nm to 10 μm, more specifically 50 nm to 5 μm And may have an average particle diameter (D ₅₀ ).

The size of the hygroscopic material may be proportional to the size of the active material. For example, the hygroscopic material may have an average particle size (D ₅₀ ) of 0.1% to 70% with respect to the average particle size (D ₅₀ ) And may have an average particle size (D ₅₀ ) size of from 1% to 67%, more specifically from 5% to 50%.

When the hygroscopic material has an average particle size of 0.1% or more with respect to the average particle size of the active material, the hygroscopic material arranges the active material and blocks the passage through which the electrolyte is impregnated And when the hygroscopic material has an average particle size of 70% or less with respect to the average particle size of the active material, the hygroscopic material is larger than the size of the void and is located in a portion other than the void, Or the total volume of the active material layer is increased to reduce the energy density per unit density.

In the present invention, the average particle diameter (D ₅₀ ) can be defined as a particle diameter based on 50% of the particle diameter distribution. The average particle diameter is not particularly limited, but can be measured using, for example, a laser diffraction method or a scanning electron microscope (SEM) photograph. In the laser diffraction method, it is generally possible to measure the particle diameter of about several millimeters from the submicron region, and high reproducibility and high degradability can be obtained.

The hygroscopic material may be contained in an amount of 1 to 20 parts by weight, preferably 2 to 10 parts by weight, more preferably 3 to 7 parts by weight based on 100 parts by weight of the active material.

If the amount of the hygroscopic material is more than 1 part by weight based on 100 parts by weight of the active material, a proper hygroscopic effect may be exhibited. If the amount of the hygroscopic substance is less than 20 parts by weight, the voids of the active material layer may be excessively decreased or the hygroscopic material may interfere with the contact , It is possible to prevent the problem of decreasing the energy density per unit density by increasing the total volume of the active material layer.

The hygroscopic substance may be a mixture of two kinds of hygroscopic substances classified according to particle size. Specifically, the mixture of hygroscopic substances may include a first hygroscopic substance having a relatively large size and a second hygroscopic substance having a relatively small size ≪ / RTI >

As described above, when the first hygroscopic material having a relatively large size and the second hygroscopic material having a relatively small size are contained, the hygroscopic material can be positioned more effectively in the gap between the active materials, It is possible to suppress the phenomenon that the total volume of the active material layer is increased due to the inclusion of the material, and thereby the energy density per unit density is decreased.

The first hygroscopic material may have an average particle diameter (D ₅₀ ) of 1 μm to 20 μm, specifically, an average particle diameter (D ₅₀ ) of 5 μm to 20 μm, more specifically, an average particle diameter of 5 μm to 10 μm D ₅₀ ), and the second hygroscopic material may have an average particle diameter (D ₅₀ ) of 10 nm to 1 μm, specifically, an average particle diameter (D ₅₀ ) of 20 nm to 500 nm, more specifically, 50 and may have an average particle diameter (D ₅₀ ) of from nm to 300 nm.

The first hygroscopic material and the second hygroscopic material may be mixed at a weight ratio of 60:40 to 99: 1, and specifically, a weight ratio of 70:30 to 98: 2, more specifically, 80:20 to 95: 5 By weight.

When the weight ratio of the first hygroscopic material and the second hygroscopic material is in the above range, the increase in the volume of the active material layer is suppressed, the hygroscopic material is evenly dispersed to further improve the hygroscopic effect and the hygroscopic material interferes with the penetration of the electrolyte Can be prevented.

The specific types of the first hygroscopic substance and the second hygroscopic substance may be the same or different, but the hygroscopic effect can be maximized by suitably combining the first and second hygroscopic substances.

In one embodiment of the present invention, the first hygroscopic substance may be at least one selected from the group consisting of silica gel, zeolite, 4A and 3A molecular sieve, crosslinked poly (acrylic acid), and poly (acrylic acid) hygroscopic materials are _{CaO, BaO, MgSO 4, Mg} (ClO 4) 2, MgO, P 2 O 5, Al 2 O 3, CaH 2, NaH, LiAlH 4, CaSO 4, Na 2 SO 4, CaCO 3, K 2 CO ₃ and Ba (ClO ₄ ) _2. Specifically, the first hygroscopic substance may be at least one selected from the group consisting of silica gel, zeolite, BaO and MgSO ₄ , and the second hygroscopic substance may be at least one selected from the group consisting of The hygroscopic material may be at least one selected from the group consisting of MgO, P ₂ O ₅ and Al ₂ O ₃ .

The active material layer of the electrode for a lithium secondary battery may have a porosity of 10% to 40%, particularly 20% to 30%, more specifically 25% to 30%, including an active material and a hygroscopic material. Lt; / RTI >

When the porosity of the active material layer satisfies the above range, the electrolytic solution can penetrate adequately and a more excellent moisture absorption effect can be obtained.

The method of positioning the hygroscopic material between the voids in which the active material is arranged and formed is not particularly limited, and includes, for example, (1) coating a slurry containing the active material on the current collector to form an active material layer; And (2) infiltrating the dispersion containing the hygroscopic material into the active material layer, so that the hygroscopic material is positioned between the voids in which the active material is arranged and formed.

At this time, the slurry may be prepared by adding a binder and a conductive material to the active material contained in the active material layer, if necessary, and mixing the slurry with a solvent. The active material layer may be further roughened after impregnating the dispersion, followed by compression and drying, and the active material layer may be preferentially dried prior to penetration of the dispersion. Through such a method, the hygroscopic material can be positioned between the voids in which the active material is arranged and is schematically shown in FIG.

The hygroscopic material may be located, for example, on the surface of the active material, between the active material layer and the current collector, or both, if necessary. When the hygroscopic substance is positioned at a position other than the air gap at all times, the hygroscopic substance is disposed in addition to the pores of the active material layer of the electrode, so that the presence of the hygroscopic substance, which is dispersed more evenly, However, the presence of the hygroscopic material located outside the gap may result in an increase in the total volume of the active material layer, so that the amount of the hygroscopic material needs to be appropriately adjusted. FIG. 2 schematically shows the form in which the hygroscopic material is located on the surface of the active material, and FIG. 3 schematically shows the form in which the hygroscopic material is located between the active material and the current collector.

The method of placing the hygroscopic material between the voids in which the active material is arranged and between the voids and the surface of the active material is not particularly limited. For example, a method of (1) applying a slurry containing the active material on the current collector to form an active material layer ; And (2) permeating the dispersion containing the hygroscopic material into the active material layer so that the hygroscopic material is positioned between the voids in which the active material is arranged and before the step (1). And dry-mixing or hard mixing the active material and the hygroscopic material to adhere the hygroscopic material to the surface of the active material.

The dry mixing may be performed by mixing the active material and the hygroscopic material without adding a binder or a thickener, and the hard mixing may be performed by mixing the active material and the hygroscopic material at a high viscosity in the presence of a very small amount of a binder or a thickener.

The hygroscopic material disposed on the pores and the hygroscopic material disposed on the surface of the active material may have a weight ratio of 99.9: 0.01 to 80:20, and more preferably 99.5: 0.5 to 90:10 Weight ratio, more specifically from 99: 1 to 95: 5.

The method of placing the hygroscopic material between the voids formed and arranged between the active material and between the active material and the current collector is not particularly limited. For example, a method of applying (1) a slurry containing an active material on a current collector Thereby forming an active material layer; And (2) permeating the dispersion containing the hygroscopic material into the active material layer so that the hygroscopic material is positioned between the voids in which the active material is arranged and before the step (1). Applying a mixture of a hygroscopic material and a binder to a solvent on the current collector. The mixture to be applied to the current collector may further include a conductive material and the like if necessary. The amount of the hygroscopic material contained in each position may be adjusted by appropriately adjusting the amount of the hygroscopic material used in each step.

The hygroscopic material located between the pores formed by arranging the active material and between the active material and the current collector may have a weight ratio of 99.9: 0.01 to 80:20, and more preferably 99.5: 0.5 to 90:10 , More specifically from 99: 1 to 95: 5.

The method of positioning the hygroscopic material between the voids formed and arranged between the active material and the surface of the active material and between the active material and the current collector is not particularly limited. For example, the active material and the hygroscopic material may be mixed by dry mixing, Mixing the hygroscopic material with the surface of the active material by hard mixing; And (2) a step of applying a slurry containing the active material with a hygroscopic material closely adhered to the surface obtained in the step (1) on a current collector to form an active material layer. Prior to the step (2) And applying a mixture of a hygroscopic substance and a binder to a solvent on the current collector. The mixture to be applied to the current collector may further include a conductive material and the like if necessary. The amount of the hygroscopic material contained in each position may be adjusted by appropriately adjusting the amount of the hygroscopic material used in each step.

The hygroscopic material located between the voids formed by the active material, the surface of the active material, and the active material may have a weight ratio of 99.9: 0.005: 0.005 to 80: 10: 10, 99.5: 0.25: 0.25 to 90: 5: 5, more specifically 99: 0.5: 0.5 to 95: 2.5: 2.5.

As described above, when the hygroscopic material is located other than the pores, the hygroscopic material may have a weight ratio of 99.9: 0.01 to 80:20 as compared with the hygroscopic material located in the pores, When the amount of the hygroscopic substance is less than 0.01 part by weight based on 99.9 parts by weight of the hygroscopic substance located in the pores, a small amount of the hygroscopic substance other than the pores may be added to increase the water absorption effect, When the amount of the hygroscopic material other than the gap is 20 parts by weight or less based on 80 parts by weight of the hygroscopic material located in the gap, the amount of the hygroscopic material other than the gap is excessively increased, The energy density per unit volume is reduced. There can stop.

In the electrode for a lithium secondary battery according to an embodiment of the present invention, the active material layer may have a moisture content of 3% by weight or less, specifically 0.1% to 2% by weight, To 0.5% by weight to 1.5% by weight.

The electrode for a lithium secondary battery may be a negative electrode or a positive electrode, and may be specifically a negative electrode.

The present invention provides a lithium secondary battery including the electrode.

The lithium secondary battery may include a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode.

When the active material layer contains the hygroscopic material, the positive electrode may be manufactured according to the manufacturing method of the electrode according to the location of the hygroscopic material, and when the hygroscopic material is not included in the active material layer, For example, a slurry may be prepared by mixing and stirring a solvent, a binder, a conductive material, and a dispersant, if necessary, in a cathode active material, and then applying (coating) Whereby a positive electrode can be manufactured.

The cathode active material may include, for example, lithium cobalt oxide (LiCoO ₂ ); Lithium nickel oxide (LiNiO _2); Li [Ni _a Co _b Mn _c M ¹ _d ] O ₂ wherein M ¹ is any one or a combination of two or more elements selected from the group consisting of Al, Ga and In, B? 0.5, 0? C? 0.5, 0? D? 0.1, a + b + c + d = 1); ^{_{Li (Li e M 2 fe-}} f 'M 3 f') O 2 - g A g ( wherein, 0≤e≤0.2, 0.6≤f≤1, 0≤f'≤0.2, 0≤g≤0.2 and M ² is at least one element selected from the group consisting of Mn, Ni, Co, Fe, Cr, V, Cu, Zn and Ti, M ³ is at least one element selected from the group consisting of Al, And A is at least one member selected from the group consisting of P, F, S and N) or a compound substituted with one or more transition metals; Li _{1 + h} Mn _{2 - h} O ₄ (where 0 _{? H?} 0.33), lithium manganese oxides such as LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula ^{_{LiNi 1 - i M 4 i O}} 2 Ni site type lithium nickel oxides represented by (wherein, M = ^4, and Co, Mn, Al, Cu, Fe, Mg, B or Ga, 0.01≤y≤0.3); Formula ^{_{LiMn 2 - j M 5 j O}} 2 ( ^{wherein, M 5 = Co, Ni,} Fe, Cr, and Zn, or Ta, 0.01≤y≤0.1) or ^{_{Li 2 Mn 3 M 6 O 8}} ( wherein, M ⁶ = Fe, Co, Ni, Cu or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; LiFe ₃ O ₄ , Fe ₂ (MoO ₄ ) ₃ , and the like, but are not limited thereto.

The current collector of the metal material is a metal having high conductivity and is a metal which can easily adhere to the slurry of the cathode active material and is not particularly limited as long as it has high conductivity without causing chemical change in the battery in the voltage range of the battery But not limited to, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, or the like. In addition, fine unevenness may be formed on the surface of the current collector to increase the adhesive force of the positive electrode active material. The current collector can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric, and may have a thickness of 3 to 500 탆.

Examples of the solvent for forming the anode include organic solvents such as N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone and dimethylacetamide, and water. These solvents may be used alone or in combination of two or more Can be mixed and used. The amount of the solvent used is sufficient to dissolve and disperse the cathode active material, the binder and the conductive material in consideration of the coating thickness of the slurry and the production yield.

Examples of the binder include polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, Polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM) Various kinds of binder polymers such as sulfonated EPDM, styrene butadiene rubber (SBR), fluorine rubber, poly acrylic acid and polymers substituted with Li, Na or Ca, or various copolymers thereof are used .

The conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; Carbon black such as acetylene black, Ketjen black, channel black, panes black, lamp black, and thermal black; Conductive fibers such as carbon fiber and metal fiber; Conductive tubes such as carbon nanotubes; Metal powders such as fluorocarbon, aluminum and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The dispersing agent may be an aqueous dispersing agent or an organic dispersing agent such as N-methyl-2-pyrrolidone.

The negative electrode can be produced by, for example, preparing a slurry by mixing a mixture of a negative electrode active material, a conductive agent and a binder on a negative electrode current collector with a predetermined solvent, applying the slurry onto a current collector, have.

As the negative electrode active material used for the negative electrode, a carbon material capable of occluding and releasing lithium ions, lithium metal, silicon or tin may be used. Preferably, carbon materials can be used, and carbon materials such as low-crystalline carbon and highly-crystalline carbon can be used. Examples of the low crystalline carbon include soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber high-temperature sintered carbon such as mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar pitch derived cokes.

The negative electrode collector may generally have a thickness of 3 [mu] m to 500 [mu] m. The negative electrode current collector is not particularly limited as long as it has electrical conductivity without causing a chemical change in the battery. The negative electrode current collector may be formed on the surface of copper, gold, stainless steel, aluminum, nickel, titanium, sintered carbon, Carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric.

The binder may be used to bind the negative electrode active material particles to maintain the formed body. Any conventional binder used in preparing the slurry for the negative electrode active material is not particularly limited, and examples thereof include polyvinyl alcohol, carboxymethyl cellulose, Polyvinylidene fluoride (PTFE), polyvinylidene fluoride (PVdF), polyethylene or polypropylene, and the like can be used. In addition, an acrylic resin such as acrylic resin (polyvinyl chloride), polyvinyl pyrrolidone, polytetrafluoroethylene Acrylonitrile-butadiene rubber, styrene-butadiene rubber, styrene-butadiene rubber, and acrylic rubber, or a mixture of two or more thereof.

The aqueous binders are economical, environmentally friendly, harmless to the health of workers, and are superior to non-aqueous binders, and have a better binding effect than non-aqueous binders. Thus, the ratio of the active materials of the same volume can be increased and the capacity of the aqueous binders can be increased. Preferably styrene-butadiene rubber can be used.

The binder may be contained in an amount of 10 wt% or less, specifically 0.1 wt% to 10 wt%, based on the total weight of the slurry for the negative electrode active material. If the content of the binder is less than 0.1 wt%, the effect of the binder is insufficient, which is undesirable. If the content of the binder is more than 10 wt%, the relative content of the active material may decrease to increase the binder content. not.

The conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the battery, and examples of the conductive material include graphite such as natural graphite and artificial graphite; Carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; And conductive materials such as polyphenylene derivatives. The conductive material may be used in an amount of 1 wt% to 9 wt% with respect to the total weight of the slurry for the negative electrode active material.

Examples of the solvent for forming the negative electrode include organic solvents such as N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone and dimethylacetamide, and water. These solvents may be used alone or in combination of two or more Can be mixed and used. The amount of the solvent to be used is sufficient to dissolve and disperse the negative electrode active material, the binder and the conductive material in consideration of the coating thickness of the slurry and the production yield.

The negative electrode may further include a thickening agent for adjusting the viscosity as needed.

The thickening agent may be a cellulose compound, and may be at least one selected from the group consisting of carboxymethylcellulose (CMC), hydroxymethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose, and specifically, carboxymethylcellulose (CMC), and the negative electrode active material and the binder may be dispersed in water together with the thickening agent to be applied to the negative electrode.

As the separator, a conventional porous polymer film conventionally used as a separator, such as a polyolefin such as an ethylene homopolymer, a propylene homopolymer, an ethylene-butene copolymer, an ethylene-hexene copolymer, and an ethylene-methacrylate copolymer, A porous polymer film made of a high molecular weight polymer may be used alone or in a laminated manner, or a nonwoven fabric made of a conventional porous nonwoven fabric such as a glass fiber having a high melting point, a polyethylene terephthalate fiber or the like may be used. It is not.

The lithium salt that can be used as the electrolyte used in the present invention may be any of those commonly used in electrolytes for lithium secondary batteries, and examples thereof include F ^- , Cl ^- , Br ^- , I ^- , NO _{3 ^{-, N (CN) 2 -}} , BF 4 -, ClO 4 -, PF 6 -, (CF 3) 2 PF 4 -, (CF 3) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF ^{_{3) 5 PF -, (CF}} 3) 6 P -, CF 3 SO 3 -, CF 3 CF 2 SO 3 -, (CF 3 SO 2) 2 N -, (FSO 2) 2 N -, CF 3 CF 2 ^{_{(CF 3) 2 CO -,}} (CF 3 SO 2) 2 CH -, (SF 5) 3 C -, (CF 3 SO 2) 3 C -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO ₂ ^- , CH ₃ CO ₂ ^- , SCN ^-, and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- .

Examples of the electrolyte used in the present invention include an organic-based liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte that can be used in the production of a lithium secondary battery. no.

The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be a cylindrical shape, a square shape, a pouch shape, a coin shape, or the like using a can.

The lithium secondary battery according to the present invention can be used not only in a battery cell used as a power source of a small device but also as a unit cell in a middle- or large-sized battery module including a plurality of battery cells.

Preferable examples of the above medium and large-sized devices include, but are not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and electric power storage systems.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples, but the present invention is not limited by these Examples and Experimental Examples. The embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Example 1: Preparation of negative electrode for lithium secondary battery including hygroscopic substance

86 parts by weight of graphite having an average particle diameter of 25 占 퐉, 1 part by weight of Denka black (conductive agent), 2 parts by weight of SBR (binder) and 1 part by weight of CMC (thickener) were mixed with NMP as a solvent to prepare an anode slurry Respectively. The prepared slurry of the negative electrode active material was coated on one side of a copper (Cu) thin film having a thickness of 10 탆 as an anode current collector to a thickness of 65 탆 to form an active material layer. After drying, a hygroscopic material having an average particle diameter (D ₅₀ ) Of silica gel in an amount of 1/10 parts by weight based on the graphite was mixed with NMP to slowly penetrate the active material layer for 30 minutes. After completion of the penetration of the mixed solution, the mixture was dried and rolled, and then punched to a predetermined size to prepare a negative electrode.

Examples 2 to 5

A negative electrode was prepared in the same manner as in Example 1 except that the particle size of the silica gel was changed as shown in Table 1 below.

Examples 6 to 10

Except that a hygroscopic material having a different size and / or type was used as a hygroscopic material instead of the silica gel having an average particle diameter (D ₅₀ ) of 0.5 μm as shown in the following Table 1, .

Example 11

The graphite in close contact with the surface of the silica gel was prepared by taking the average particle diameter is mixed with 25 ㎛ graphite 100 average particle size as the parts by weight of a hygroscopic material (D ₅₀₎ 0.5 ㎛ of silica gel 1 parts by weight, stirring for 30 minutes 25 rpm speed Articles .

86 parts by weight of graphite, 1 part by weight of Denka black (conductive agent) and 2 parts by weight of SBR (binder), and 1 part by weight of CMC (thickener) were mixed with NMP as a solvent to form a negative electrode slurry . The prepared slurry of the negative electrode active material was coated on one side of a copper (Cu) thin film having a thickness of 10 탆 as an anode current collector to a thickness of 65 탆 to form an active material layer. After drying, a hygroscopic material having an average particle diameter (D ₅₀ ) Of silica gel was mixed with NMP so as to be in an amount of 9/100 parts by weight based on the graphite, was slowly infiltrated into the active material layer for 30 minutes. After completion of the penetration of the mixed solution, the mixture was dried and rolled, and then punched to a predetermined size to prepare a negative electrode.

Example 12

A silica gel having an average particle diameter (D ₅₀ ) of 2 탆 and P ₂ O ₅ having an average particle diameter (D ₅₀ ) of 100 nm were changed to a silica gel having an average particle diameter (D ₅₀ ) of 0.5 탆 as a hygroscopic substance in an amount of 80: 20 weight ratio was used as a negative electrode active material.

Example 13

100 parts by weight of graphite having an average particle diameter of 25 탆, 3 parts by weight of a silica gel having an average particle diameter (D ₅₀ ) of 2 탆 as a hygroscopic material and P ₂ O ₅ having an average particle diameter (D ₅₀ ) of 100 nm at a weight ratio of 80:20 Were mixed by gun mixing at 25 rpm for 30 minutes to prepare graphite in which the silica gel and P ₂ O ₅ adhered to the surface.

86 parts by weight of graphite, ₂ parts by weight of Denka black (conductive agent) and 2 parts by weight of SBR (binder), and 1 part by weight of CMC (thickener) in which silica gel and P ₂ O ₅ adhered to the surface were adhered as negative active materials, To prepare an anode slurry. The prepared slurry of the negative electrode active material was coated on one surface of a copper (Cu) thin film having a thickness of 10 탆 as an anode current collector to a thickness of 65 탆 to form an active material layer. After drying, a hygroscopic material having an average particle diameter (D ₅₀ ) Of silica gel and P ₂ O ₅ having an average particle diameter (D ₅₀ ) of 100 nm at a weight ratio of 80:20 was mixed with NMP in an amount of 7/100 parts by weight relative to the graphite was added to the active material layer Slowly penetrated for minutes. After completion of the penetration of the mixed solution, the mixture was dried and rolled, and then punched to a predetermined size to prepare a negative electrode.

Example 14

A mixture of 80 parts by weight of silica gel having a particle diameter of 0.5 mu m, 1 part by weight of Denka black (conductive agent) and 2 parts by weight of SBR (binder) with NMP as a solvent was added to a copper (Cu) thin film And then dried at a thickness of 2 탆. At this time, the amount of silica gel was used in an amount of 1/100 parts by weight relative to graphite, which is an anode active material.

86 parts by weight of graphite having an average particle diameter of 25 占 퐉, 1 part by weight of Denka black (conductive agent), 2 parts by weight of SBR (binder) and 1 part by weight of CMC (thickener) were mixed with NMP as a solvent to prepare an anode slurry Respectively. The prepared slurry of the negative active material was coated on the copper thin film coated with the mixture to a thickness of 65 탆 to form an active material layer. After drying, a silica gel having a particle size of 0.5 탆 as a hygroscopic material was added in an amount of 9/100 parts by weight Was added to the active material layer for 30 minutes to slowly infiltrate the active material layer. After completion of the penetration of the mixed solution, the mixture was dried and rolled, and then punched to a predetermined size to prepare a negative electrode.

Example 15

In Example 14, as a hygroscopic material to the average particle diameter (D ₅₀₎ in place of the silica gel of 0.5 ㎛ 80:20 to silica gel having an average particle size (D ₅₀₎ 2 ㎛ silica gel with average particle diameter (D ₅₀₎ 100 nm in the weight ratio A negative electrode was prepared in the same manner as in Example 14 except that a mixed mixture was used.

Example 16

, 80 parts by weight of a mixture of silica gel having an average particle diameter (D ₅₀ ) of 2 탆 and P ₂ O ₅ having an average particle diameter (D ₅₀ ) of 100 nm at a weight ratio of 80:20, 1 part of Denka black And 2 parts by weight of NMP as a solvent was coated on one side of a copper (Cu) thin film as an anode current collector of 10 탆 at a thickness of 2 탆 and then dried. At this time, the amount of the mixture was used in an amount of 1/10 parts by weight relative to the graphite as the negative electrode active material.

86 parts by weight of graphite having an average particle diameter of 25 占 퐉, 1 part by weight of Denka black (conductive agent), 2 parts by weight of SBR (binder) and 1 part by weight of CMC (thickener) were mixed with NMP as a solvent to prepare an anode slurry Respectively. The coating manufacturing a negative electrode active material slurry to a thickness of 65 ㎛ a copper film wherein the mixture is applied to form an active material layer, and the silica gel of the dry later, the average particle diameter (D ₅₀₎ 2 ㎛ as a hygroscopic material to the average particle diameter (D ₅₀ ) 100 nm of P ₂ O ₅ at a weight ratio of 80:20 was mixed with NMP so as to be in an amount of 9/100 parts by weight based on the graphite, was slowly permeated into the active material layer for 30 minutes. After completion of the penetration of the mixed solution, the mixture was dried and rolled, and then punched to a predetermined size to prepare a negative electrode.

Example 17

100 parts by weight of graphite having an average particle diameter of 25 占 퐉 and 0.5 part by weight of silica gel having a particle diameter of 0.5 占 퐉 were subjected to dry mixing and hard mixing to produce graphite in which the silica gel was in close contact with the surface.

A mixture of 80 parts by weight of silica gel having a particle diameter of 0.5 mu m, 1 part by weight of Denka black (conductive agent) and 2 parts by weight of SBR (binder) with NMP as a solvent was added to a copper (Cu) thin film And then dried at a thickness of 2 탆. At this time, the amount of the silica gel was used in an amount of 1/200 parts by weight relative to the graphite as the negative electrode active material.

86 parts by weight of graphite, 1 part by weight of Denka black (conductive agent) and 2 parts by weight of SBR (binder), and 1 part by weight of CMC (thickener) were mixed with NMP as a solvent to form a negative electrode slurry . The prepared slurry of the negative active material was coated on the copper thin film coated with the mixture to a thickness of 65 탆 to form an active material layer. After drying, a silica gel having a particle size of 0.5 탆 as a hygroscopic material was added in an amount of 9/100 parts by weight Was added to the active material layer for 30 minutes to slowly infiltrate the active material layer. After completion of the penetration of the mixed solution, the mixture was dried and rolled, and then punched to a predetermined size to prepare a negative electrode.

Example 18

The procedure of Example 17 was repeated except that a hygroscopic material having a different size and / or type was used as the hygroscopic material in place of the silica gel having a particle diameter of 0.5 탆 as shown in the following Table 1 Thereby preparing a negative electrode.

Example 19

The average particle diameter of 25 ㎛ graphite 100 parts by weight and an average particle diameter (D ₅₀₎ 2 parts by weight of 2 ㎛ silica gel with average particle diameter (D ₅₀₎ for mixing a mixture of a mixture of 80: 20 to 100 nm P ₂ O ₅ weight ratio Articles And hard-mixed to prepare a graphite in which a mixture of the silica gel and P ₂ O ₅ adhered to the surface.

, 80 parts by weight of a mixture of silica gel having an average particle diameter (D ₅₀ ) of 2 탆 and P ₂ O ₅ having an average particle diameter (D ₅₀ ) of 100 nm at a weight ratio of 80:20, 1 part of Denka black And 2 parts by weight of NMP as a solvent was coated on one side of a copper (Cu) thin film as an anode current collector of 10 탆 at a thickness of 2 탆 and then dried. At this time, the amount of the silica gel was used in an amount of 2/100 parts by weight based on graphite as the negative electrode active material.

86 parts by weight of graphite in which the mixture of silica gel and P ₂ O ₅ adhered to the surface, 1 part by weight of Denka black (conductive agent), 2 parts by weight of SBR (binder) and 1 part by weight of CMC (thickener) And mixed with NMP to prepare an anode slurry. The coating manufacturing a negative electrode active material slurry to a thickness of 65 ㎛ a copper film wherein the mixture is applied to form an active material layer, and the silica gel of the dry later, the average particle diameter (D ₅₀₎ 2 ㎛ as a hygroscopic material to the average particle diameter (D ₅₀ ) 100 nm P ₂ O ₅ at a weight ratio of 80:20 was mixed with NMP in an amount of 6/100 parts by weight based on the graphite was slowly permeated into the active material layer for 30 minutes. After completion of the penetration of the mixed solution, the mixture was dried and rolled, and then punched to a predetermined size to prepare a negative electrode.

Example 20

86 parts by weight of graphite having an average particle diameter of 25 占 퐉, 1 part by weight of Denka black (conductive agent), 2 parts by weight of SBR (binder) and 1 part by weight of CMC (thickener) were mixed with NMP as a solvent to prepare an anode slurry Respectively. The prepared slurry of the negative electrode active material was coated on one surface of a copper (Cu) thin film having a thickness of 10 탆 as an anode current collector to a thickness of 65 탆 to form an active material layer. After drying, a hygroscopic material having an average particle diameter (D ₅₀ ) Of silica gel and P ₂ O ₅ having an average particle diameter (D ₅₀ ) of 5 nm at a weight ratio of 80:20 was mixed with NMP so as to be in an amount of 9/100 parts by weight based on the graphite, was added to the active material layer Slowly penetrated for minutes. After completion of the penetration of the mixed solution, the mixture was dried and rolled, and then punched to a predetermined size to prepare a negative electrode.

Comparative Example 1

100 parts by weight of graphite having an average particle diameter of 25 占 퐉 and 10 parts by weight of silica gel having a particle diameter of 0.5 占 퐉 were subjected to dry mixing and hard mixing to produce graphite in which the silica gel was in close contact with the surface.

86 parts by weight of graphite, 1 part by weight of Denka black (conductive agent) and 2 parts by weight of SBR (binder), and 1 part by weight of CMC (thickener) were mixed with NMP as a solvent to form a negative electrode slurry . The prepared slurry of the negative electrode active material was coated on one surface of a copper (Cu) thin film having a thickness of 10 μm as a current collector to a thickness of 65 μm to form an active material layer, which was dried and rolled, .

Comparative Example 2

A mixture of 80 parts by weight of silica gel having a particle diameter of 0.5 mu m, 1 part by weight of Denka black (conductive agent) and 2 parts by weight of SBR (binder) with NMP as a solvent was added to a copper (Cu) thin film And then dried at a thickness of 2 탆.

86 parts by weight of graphite, 1 part by weight of Denka black (conductive agent), 2 parts by weight of SBR (binder) and 1 part by weight of CMC (thickener) as negative active material were mixed with NMP as a solvent to prepare an anode slurry. The prepared negative electrode active material slurry was coated on the copper thin film coated with the mixture to a thickness of 65 占 퐉 to form an active material layer. The active material layer was dried and rolled, and then punched to a predetermined size to prepare a negative electrode.

Example Hygroscopic
matter Hygroscopic
Mix ratio (weight ratio) Average particle size (D ₅₀ ) Hygroscopic
Location (content ratio) One Silica gel - 0.5 탆 air gap 2 Silica gel - 5 탆 air gap 3 Silica gel - 100 nm air gap 4 Silica gel - 30 탆 air gap 5 Silica gel - 5 nm air gap 6 Silica gel
/ Silica gel 80:20 2 탆
/ 100 nm air gap 7 Silica gel
/ P ₂ O ₅ 80:20 2 탆
/ 100 nm air gap 8 Silica gel
/ P ₂ O ₅ 80:20 2 탆
/ 2 탆 air gap 9 Silica gel
/ P ₂ O ₅ 30:70 2 탆
/ 100 nm air gap 10 Silica gel
/ P ₂ O ₅ 99.5: 0.5 2 탆
/ 100 nm air gap 11 Silica gel - 0.5 탆 Pore, active material surface (90:10) 12 Silica gel
/ P ₂ O ₅ 80:20 2 탆
/ 100 nm Pore, active material surface (90:10) 13 Silica gel
/ P ₂ O ₅ 80:20 2 탆
/ 100 nm Pore, active material surface (70:30) 14 Silica gel - 0.5 탆 Pore, between active material and current collector (90:10) 15 Silica gel
/ Silica gel 80:20 2 탆
/ 100 nm Pore, between active material and current collector (90:10) 16 Silica gel
/ P ₂ O ₅ 80:20 2 탆
/ 100 nm Pore, between active material and current collector (70:30) 17 Silica gel - 0.5 탆 Voids, active material surface,
Between active material and current collector
(90: 5: 5) 18 Silica gel
/ Silica gel 80:20 2 탆
/ 100 nm Voids, active material surface,
Between active material and current collector
(90: 5: 5) 19 Silica gel
/ P ₂ O ₅ 80:20 2 탆
/ 100 nm Voids, active material surface,
Between active material and current collector
(60:20:20) 20 Silica gel
/ P ₂ O ₅ 80:20 2 탆
/ 5 nm air gap Comparative Example 1 Silica gel - 0.5 탆 Active material surface Comparative Example
2 Silica gel - 0.5 탆 Between active material and current collector

Examples 1-1 to 20-1: Production of negative electrode for lithium secondary battery including hygroscopic material

After a porous polyethylene membrane having a thickness of 17 탆 was interposed between the negative electrode and the lithium metal prepared in each of Examples 1 to 20, ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 30:70 An electrolyte in which 1 M LiPF ₆ was dissolved in a solvent was injected to prepare coin type half cells.

Comparative Examples 1-1 to 2-1: Production of negative electrode for lithium secondary battery containing hygroscopic material

A porous polyethylene membrane having a thickness of 17 탆 was interposed between the negative electrode and lithium metal prepared in each of Comparative Examples 1 and 2, and then ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 30:70 An electrolyte in which 1 M LiPF ₆ was dissolved in a solvent was injected to prepare coin type half cells.

Experimental Example 1: Cycle Characterization Experiment

Electrochemical evaluation experiments were carried out as follows to confirm the cycle characteristics of the coin-type half-cells obtained in Examples 1-1 to 20-1 and Comparative Examples 1-1 and 2-1, respectively.

Specifically, the coin-shaped half cells obtained in each of Examples 1-1 to 20-1 and Comparative Examples 1-1 and 2-1 were charged at a constant current (CC) of 0.5 C at 25 캜 until the voltage became 0.005 V , And then charged at a constant voltage (CV) until the charge current reached 0.005 C (cut-off current). Thereafter, it was left for 20 minutes and then discharged at a constant current (CC) of 0.5 C until it reached 1.5 V. [ This was repeated in 1 to 100 cycles. The results of measuring the capacity retention rate of the battery after 100 cycles are shown in Fig.

Referring to FIG. 4, it can be seen that the 100-cycle capacity retention ratio is better than the larger particle size of the hygroscopic material. Specifically, from the results of Examples 1-1 to 4-1, it can be seen that the cycle performance is improved when the particle diameter of the hygroscopic material is small. However, as can be seen from Example 5-1, when the particle diameter of the hygroscopic material was too small, it was confirmed that the cycle performance was adversely affected due to the electrolyte consumption due to the side reaction of the electrolyte on the surface.

On the other hand, it can be confirmed that the 100-cycle capacity retention ratio varies depending on the hygroscopic material. Specifically, when the results of Example 1-1 and Comparative Examples 1-1 and 2-1 are compared, although the types of the hygroscopic materials are the same, the capacity retention ratios after 100 cycles are different depending on their positions, It can be confirmed that it is superior to the surface of the active material or between the active material and the current collector and to be located on the surface of the active material rather than between the active material and the current collector.

On the other hand, when two hygroscopic materials having different sizes and two hygroscopic materials having different hygroscopic materials are used in combination, it can be seen that the 100-cycle capacity retention ratio is higher than that when not used.

100: House full
200: active material
210: Pore
300: hygroscopic substance

Claims (19)

1. An electrode for a lithium secondary battery comprising an active material layer and a current collector,
Wherein the active material layer includes an active material and a hygroscopic material, and the hygroscopic material is located between voids in which the active material is arranged and formed in the active material layer.
The method according to claim 1,
The hygroscopic material is silica gel, _{zeolite, CaO, BaO, MgSO 4,} Mg (ClO 4) 2, MgO, P 2 O 5, Al 2 O 3, CaH 2, NaH, LiAlH 4, CaSO 4, Na 2 SO 4 , At least one selected from the group consisting of CaCO ₃ , K ₂ CO ₃ , CaCl ₂ , 4A and 3A molecular sieve, Ba (ClO ₄ ) ₂ , crosslinked poly (acrylic acid) The electrode for a lithium secondary battery.
The method according to claim 1,
Wherein the active material has an average particle diameter (D ₅₀ ) of 0.1 to 30 μm.
The method according to claim 1,
Wherein the void has a size of 0.01 to 20 占 퐉.
The method according to claim 1,
The hygroscopic material may have a mean particle size (D ₅₀₎ of a size from 0.1 to 70% relative to the average particle diameter (D ₅₀₎ of the active material for a lithium secondary battery electrode.
The method according to claim 1,
Wherein the hygroscopic material is contained in an amount of 1 to 20 parts by weight based on 100 parts by weight of the active material.
The method according to claim 1,
Wherein the hygroscopic substance is a mixture of a first hygroscopic substance having an average particle diameter (D ₅₀ ) of 1 μm to 20 μm and a second hygroscopic substance having an average particle diameter (D ₅₀ ) of 10 nm to 1 μm.
8. The method of claim 7,
Wherein the first hygroscopic material and the second hygroscopic material are mixed at a weight ratio of 60:40 to 99: 1.
8. The method of claim 7,
The first hygroscopic substance is at least one selected from the group consisting of silica gel, zeolite, 4A and 3A molecular sieve, cross-linked poly (acrylic acid), and poly (acrylic acid)
The second absorbent material is _{CaO, BaO, MgSO 4, Mg} (ClO 4) 2, MgO, P 2 O 5, Al 2 O 3, CaH 2, NaH, LiAlH 4, CaSO 4, Na 2 SO 4, CaCO 3 , K ₂ CO _3, and Ba (ClO ₄ ) ₂ .
The method according to claim 1,
Wherein the active material layer has a porosity of 10 to 40%.
The method according to claim 1,
The hygroscopic material is further disposed on the surface of the active material other than the gap,
Wherein the hygroscopic material located in the gap and the hygroscopic material located on the surface of the active material have a weight ratio of 99.9: 0.01 to 80:20.
The method according to claim 1,
The hygroscopic material is further disposed between the active material layer and the current collector in addition to the gap,
Wherein the hygroscopic material located in the gap and the hygroscopic material located between the active material layer and the current collector have a weight ratio of 99.9: 0.01 to 80:20.
The method according to claim 1,
Wherein the hygroscopic material is additionally located on the surface of the active material other than the pores and between the active material layer and the current collector,
Wherein the hygroscopic material positioned between the pores, the surface of the active material and the active material layer has a weight ratio of 99.9: 0.005: 0.005 to 80:10:10.
The method according to claim 1,
Wherein the active material layer has a water content of 3% by weight or less.
A lithium secondary battery comprising an electrode according to any one of claims 1 to 14.
(1) applying a slurry containing an active material on a current collector to form an active material layer; And
(2) A method for manufacturing an electrode for a lithium secondary battery, comprising: impregnating the active material layer with a dispersion containing a hygroscopic material so that the hygroscopic material is positioned between voids in which the active material is arranged and formed.
17. The method of claim 16,
Further comprising a step of subjecting the active material and the hygroscopic material to dry mixing or hard mixing before the step (1) to adhere the hygroscopic material to the surface of the active material.
17. The method of claim 16,
Further comprising a step of applying a mixture of a hygroscopic material and a binder in a solvent on the current collector prior to the step (1).
19. The method of claim 18,
Further comprising a step of applying a mixture of a hygroscopic material and a binder in a solvent on the current collector prior to the step (2).

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