KR20150049999A - Electrode and electrochemical device including the same - Google Patents

Abstract

The present invention relates to an electrode and an electrochemical device including the same and, more precisely, to an electrode including: an electrode current collector; a first electrode active material layer formed on at least one side of the electrode current collector, and including a first electrode active material having particle size of 1-20 μm; and a second electrode active material layer formed on the upper surface of the first electrode active material layer, and including a second electrode active material having particle size of 10-100 μm, and to an electrochemical device including the same. According to the present invention, an electrode active material layer including relatively small size electrode active material is formed on a lower layer to reduce diffusion resistance in an electrode active material layer around a current collector having long moving distance of lithium, and an electrode active material layer including relatively big electrode active material is formed on an upper layer to reduce the specific surficial area of the electrode active material layer around a separator in which a side reaction is intensely developed, so that the side reaction is reduced, thereby improving output and long term durability of the electrochemical device.

Description

ELECTRODE AND ELECTROCHEMICAL DEVICE INCLUDING THE Same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode and an electrochemical device including the electrode, and more particularly, to an electrochemical device including the electrode of the type capable of improving both the output and the long-term life.

Recently, interest in energy storage technology is increasing. As the application fields of cell phones, camcorders, notebook PCs and even electric vehicles are expanding, efforts for research and development of electrochemical devices are becoming more and more specified. The electrochemical device has received the most attention in this respect. Of these, the development of a rechargeable secondary battery has become a focus of attention. Recently, in developing such a battery, Research and development on the design of electrodes and batteries are underway.

Among the currently applied secondary batteries, the lithium secondary battery developed in the early 1990s has advantages such as higher operating voltage and higher energy density than conventional batteries such as Ni-MH, Ni-Cd and sulfuric acid-lead batteries using an aqueous electrolyte solution .

On the other hand, an electrode used in an electrochemical device is manufactured by applying an electrode active material slurry containing an electrode active material on at least one surface of an electrode current collector, followed by drying.

However, conventionally, an electrode active material slurry in which electrode active material particles having a small relative standard deviation of particle size, that is, a uniform size, is dispersed is applied to an electrode current collector to form an electrode.

At this time, when the size of the electrode active material particles is relatively small, that is, when the specific surface area is relatively high, the resistance of the electrode active material layer decreases, and the output of the electrochemical device can be improved. However, On the other hand, when the size of the electrode active material particles is relatively large, that is, when the specific surface area is relatively low, it is advantageous in terms of long-term life performance. However, the resistance of the electrode active material layer increases, .

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrode capable of simultaneously achieving an improvement in output of an electrochemical device and an improvement in long-term service life by forming two electrode active material layers having different particle sizes in the thickness direction of the electrode And an electrochemical device including the same.

According to an aspect of the present invention, there is provided an electrode collector, A first electrode active material layer formed on at least one surface of the electrode current collector and including a first electrode active material having a particle size of 1 to 20 m; And a second electrode active material layer formed on the first electrode active material layer and including a second electrode active material having a particle size of 10 to 100 占 퐉.

The specific surface area of the first electrode active material layer may be 0.1 to 20 m ² / g.

The specific surface area of the second electrode active material layer may be 0.01 to 5 m ² / g.

The ratio of the thickness of the first electrode active material layer to the thickness of the second electrode active material layer may be 20:80 to 80:20.

The electrode is an anode, and the first electrode active material and the second electrode active material may be lithium-containing oxides, respectively.

The lithium-containing transition metal oxide may be at least one selected from the group consisting of Li _x CoO ₂ (0.5 <x <1.3), Li _x NiO ₂ (0.5 <x <1.3), Li _{x MnO 2 (0.5 <x <} 1.3), Li x Mn 2 O 4 (0.5 <x <1.3), Li x (Ni a Co b Mn c) O 2 (0.5 <x <1.3, 0 <a <1, 0 <b <1, 0 < c <1, a + b + c = 1), Li x Ni 1 -y Co y O 2 (0.5 <x <1.3, 0 <y <1), Li x Co 1 - _{y Mn y O 2 (0.5 <} x <1.3, 0≤y <1), Li x Ni 1 -y Mn y O 2 (0.5 <x <1.3, O≤y <1), Li x (Ni a Co b Mn _c ) O ₄ (0.5 <x <1.3, 0 <a <2, 0 <b <2, 0 <c <2, a + b + c = 2), Li _x Mn _{2 -z} Ni _z O ₄ 0.5 <x <1.3, 0 < z <2), Li x Mn 2 -z Co z O 4 (0.5 <x <1.3, 0 <z <2), Li x CoPO 4 (0.5 <x <1.3) , and Li _x FePO ₄ may be (0.5 <x <1.3) or any mixture of two or more of those selected from the group consisting of.

The electrode may be a cathode, and the first electrode active material and the second electrode active material may be any one selected from the group consisting of lithium metal, carbonaceous material, and metal compound, or a mixture of two or more thereof.

The metal compound is composed of Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, Or a mixture of two or more thereof.

According to another aspect of the present invention, there is provided an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; A nonaqueous electrolytic solution for impregnating the electrode assembly; And a battery case containing the electrode assembly and the non-aqueous electrolyte, wherein at least one of the positive electrode and the negative electrode is an electrode of the present invention.

At this time, the non-aqueous electrolyte may include an organic solvent and an electrolyte salt.

The organic solvent may be at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, (DEC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), dimethyl carbonate (DMF) Methyl ethyl ketone, ethyl propyl carbonate, dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, Propyl propionate,? -Butyrolactone,? -Valerolactone,? -Caprolactone,? -Valerolactone and? -Caprolactone Ton, or a mixture of two or more thereof.

In addition, the electrolyte salt is a negative ^{ion, 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 ^- , or two or more of them.

The electrochemical device may be a lithium secondary battery.

According to an embodiment of the present invention, an electrode active material layer including a relatively small-sized electrode active material is formed on the lower layer so that the diffusion resistance in the electrode active material layer in the vicinity of the current collector having a large lithium- Since the electrode active material layer including the electrode active material having a relatively large size can be formed on the upper layer and the side reaction can be reduced by lowering the specific surface area in the electrode active material layer in the vicinity of the separator where the side reaction is vigorous, Both of the output and long-term performance of the device can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given above, serve to further the understanding of the technical idea of the invention, It should not be construed as limited.
1 is a cross-sectional view schematically showing a cross section of an electrode according to an embodiment of the present invention.
2 is a cross-sectional view schematically showing a cross section of an electrode according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. 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.

Therefore, the embodiments described in the present specification and the constitutions described in the drawings are merely the most preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

1 and 2 are sectional views schematically showing cross sections of an electrode according to an embodiment of the present invention.

1 and 2, the electrodes 100 and 200 according to the present invention include an electrode current collector 10; A first electrode active material layer 20 formed on at least one surface of the electrode current collector 10 and including a first electrode active material 21 having a particle size of 1 to 20 탆; And a second electrode active material layer 30 formed on the first electrode active material layer 20 and including a second electrode active material 31 having a particle size of 10 to 100 탆.

As shown in FIG. 1, the first electrode active material layer 20 and the second electrode active material layer 30 may be sequentially formed on only one side of the electrode current collector 10, and the electrode current collector 10 As shown in Fig.

Conventionally, an electrode is formed by applying a slurry of an electrode active material in which electrode active material particles having a small relative standard deviation of particle size, that is, a uniform size, is dispersed to a collector of the electrode only as a single layer. When the size is relatively small, that is, when the specific surface area is relatively high, the resistance of the electrode active material layer is reduced and the output of the electrochemical device can be improved. However, due to a strong side reaction in the electrode active material layer near the separator, There has been a problem that this can be exacerbated.

However, according to the present invention, an electrode active material layer including a relatively small-sized electrode active material is formed in the lower layer, and the resistance can be reduced by lowering the diffusion resistance in the electrode active material layer in the vicinity of the current collector, Since the electrode active material layer including the electrode active material having a relatively large size is formed on the upper layer to reduce the specific surface area in the electrode active material layer near the separator where the side reaction is vigorous, It is possible to improve both the long-life performance.

In this case, the specific surface area of the first electrode active material layer may be 0.1 to 20 m ² / g. If the numerical range is satisfied, diffusion resistance of the electrode active material layer in the vicinity of the current collector, The resistance can be reduced and the output of the electrochemical device can be improved.

The specific surface area of the second electrode active material layer may be 0.01 to 5 m ² / g. If the numerical range is satisfied, the side reaction in the electrode active material layer in the vicinity of the separator can be reduced, The long-term service life of the battery can be improved.

The first electrode active material layer and the second electrode active material layer may be coated simultaneously by a multilayer coating method. The thickness ratio of the first electrode active material layer and the second electrode active material layer may be 20:80 to 80 : 20, and if the numerical range is satisfied, it is possible to maintain the output characteristics of the electrochemical device and improve the long-term life performance.

On the other hand, the electrode may be a positive electrode, and the positive electrode has a structure in which a positive electrode active material layer including a positive electrode active material, a conductive material and a binder is formed on one surface or both surfaces of the positive electrode current collector.

The cathode active material may be a lithium-containing oxide, and a lithium-containing transition metal oxide may be preferably used. For example, the lithium-containing transition metal _{oxides, Li x CoO 2 (0.5 <} x <1.3), Li x NiO 2 (0.5 <x <1.3), Li x MnO 2 (0.5 <x <1.3), Li x _{Mn 2 O 4 (0.5 <x} <1.3), Li x (Ni a Co b Mn c) O 2 (0.5 <x <1.3, 0 <a <1, 0 <b <1, 0 <c <1, a + b + c = 1), Li x Ni 1 -y Co y O 2 (0.5 <x <1.3, 0 <y <1), Li x Co 1 -y Mn y O 2 (0.5 <x <1.3, 0 _{≤y <1), Li x Ni} 1 -y Mn y O 2 (0.5 <x <1.3, O≤y <1), Li x (Ni a Co b Mn c) O 4 (0.5 <x <1.3, 0 2, 0 <b <2, 0 <c <2, a + b + c = 2), Li _x Mn _{2 -z} Ni _z O ₄ (0.5 <x <1.3, 0 <z <2) Li _x Mn _{2 -z} Co _z O ₄ (0.5 <x <1.3, 0 <z <2), Li _x CoPO ₄ (0.5 <x <1.3) and Li _x FePO ₄ Or a mixture of two or more thereof. The lithium-containing transition metal oxide may be coated with a metal such as aluminum (Al) or a metal oxide. In addition to the lithium-containing transition metal oxide, sulfide, selenide and halide may also be used.

The conductive material is not particularly limited as long as it is an electron conductive material that does not cause a chemical change in an electrochemical device. In general, carbon black, graphite, carbon fiber, carbon nanotube, metal powder, conductive metal oxide, organic conductive material and the like can be used. Commercially available products as the conductive material include acetylene black series (manufactured by Chevron Chemical Co., (Chevron Chemical Company or Gulf Oil Company products), Ketjen Black EC series (Armak Company), Vulcan XC-72 (Cabot Company) and Super P (MM (MMM)). For example, acetylene black, carbon black and graphite.

Meanwhile, the electrode may be a negative electrode, and the negative electrode has a structure in which a negative electrode active material layer including a negative electrode active material, a conductive material, and a binder is formed on one or both surfaces of the negative electrode collector.

As the negative electrode active material, a lithium metal, a carbonaceous material, a metal compound, or a mixture of lithium metal, a carbonaceous material, and a metal compound, in which lithium ions can be occluded and released, may be used.

Concretely, as the carbon material, both low-crystalline carbon and highly-crystalline carbon may 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.

Examples of the metal compound include metal elements such as Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, Mg, , And the like. These metal compounds may be a single substance, an alloy, an oxide (TiO ₂ , SnO ₂ Or the like), a nitride, a sulfide, a boride, an alloy with lithium, or the like, but an alloy with a single substance, an alloy, an oxide, and lithium can be increased in capacity. Among them, it may contain at least one element selected from Si, Ge and Sn, and it may further increase the capacity of the battery including at least one element selected from Si and Sn.

The binder used for the positive electrode and the negative electrode has a function of holding the positive electrode active material and the negative electrode active material in respective current collectors and connecting the active materials, and a commonly used binder may be used without limitation.

For example, polyvinylidene fluoride-hexafluoropropylene (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate various kinds of binders such as polymethyl methacrylate, styrene butadiene rubber (SBR), and carboxyl methyl cellulose (CMC) can be used.

The current collector used for the positive electrode and the negative electrode may be any metal having a high conductivity and being a metal capable of easily adhering the electrode active material slurry but not reactive in the voltage range of the electrochemical device. Specifically, non-limiting examples of the current collector for a positive electrode include aluminum, nickel, or a foil produced by a combination thereof. Non-limiting examples of the current collector for a negative electrode include copper, gold, nickel or a copper alloy, And the like. In addition, the current collector may be used by laminating the substrates made of the above materials.

The positive electrode and the negative electrode are kneaded using an active material, a conductive material, a binder and a high boiling point solvent to prepare two types of electrode active material slurries each containing an electrode active material having a different particle size, And then drying, pressing and molding the mixture at a temperature of about 50 to 250 ° C for about 2 hours under a vacuum.

According to another aspect of the present invention, there is provided an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; A nonaqueous electrolytic solution for impregnating the electrode assembly; And a battery case containing the electrode assembly and the non-aqueous electrolyte, wherein at least one of the positive electrode and the negative electrode is an electrode of the present invention.

The separator according to the present invention can be used as a porous substrate used in an electrochemical device. For example, a polyolefin porous membrane or a nonwoven fabric may be used, but the present invention is not limited thereto.

Examples of the polyolefin-based porous film include polyolefin-based polymers such as polyethylene, polypropylene, polybutylene, and polypentene, such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene and ultra-high molecular weight polyethylene, One membrane can be mentioned.

The nonwoven fabric may include, in addition to the polyolefin nonwoven fabric, for example, polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate ), Polyimide, polyetheretherketone, polyethersulfone, polyphenylene oxide, polyphenylenesulfide, and polyethylene naphthalene, which may be used alone or in combination, And nonwoven fabrics formed by mixing these polymers. The structure of the nonwoven fabric may be a spun bond nonwoven fabric or a meltblown nonwoven fabric composed of long fibers.

The thickness of the porous substrate is not particularly limited, but may be 5 to 50 μm, and the pore size and porosity present in the porous substrate are also not particularly limited, but may be 0.01 to 50 μm and 10 to 95%, respectively.

On the other hand, in order to improve the mechanical strength of the separator composed of the porous substrate and to prevent a short circuit between the anode and the cathode, a porous coating layer containing inorganic particles and a polymeric binder may be further provided on at least one surface of the porous substrate.

In the porous coating layer, the polymer binder binds the inorganic particles together (that is, the polymer binder binds and fixes the inorganic particles) so that the inorganic particles can remain bonded to each other, and the porous coating layer binds the porous substrate with the polymer binder . The inorganic particles of the porous coating layer exist in a closely packed state in a state of being substantially in contact with each other, and the interstitial volume generated when the inorganic particles are in contact becomes the pores of the porous coating layer.

At this time, the inorganic particles used are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles are not particularly limited as long as the oxidation and / or reduction reaction does not occur in the operating voltage range of the applied electrochemical device (for example, 0 to 5 V based on Li / Li ⁺ ). Particularly, when inorganic particles having ion transfer ability are used, the ion conductivity in the electrochemical device can be increased to improve the performance.

When inorganic particles having a high dielectric constant are used as the inorganic particles, dissociation of an electrolyte salt, for example, a lithium salt, in the liquid electrolyte is also increased, and ion conductivity of the electrolyte can be improved.

For the reasons stated above, the inorganic particles may include high-permittivity inorganic particles having a dielectric constant of 5 or more, or 10 or more, inorganic particles having lithium ion-transporting ability, or a mixture thereof.

Nonlimiting examples of inorganic particles having a dielectric constant of 5 or more include BaTiO ₃ , Pb (Zr _x Ti _{1 -x} ) O ₃ (PZT, where 0 <x <1), Pb _{1 - x} La _x Zr _{1 - y} Ti _y O ₃ (PLZT, where, 0 <x <1, 0 <y <1 Im), (1-x) Pb (Mg 1/3 Nb 2/3) O 3 -xPbTiO 3 (PMN-PT, where 0 < xO, x <1), hafnia (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , SiC, TiO ₂ May be used alone or in combination of two or more.

In particular, the above-described _{BaTiO 3, Pb (Zr x Ti} 1 -x) O 3 (PZT, where 0 <x <1), Pb 1 - x La x Zr 1 -y Ti y O 3 (PLZT, where 0 < x <1, 0 <y < 1 Im), (1-x) Pb (Mg 1/3 Nb 2/3) O 3 - x PbTiO 3 (PMN-PT, where 0 <x <1), hafnia ( HfO ₂ ) exhibits a high dielectric constant with a dielectric constant of 100 or more, as well as a piezoelectricity in which a potential difference is generated between both surfaces due to the generation of charge when a certain pressure is applied to the piezoelectric element by being stretched or compressed. It is possible to prevent internal short-circuiting of both electrodes due to the impact, thereby improving the safety of the electrochemical device. Further, when the above-mentioned high-permittivity inorganic particles and inorganic particles having lithium ion transferring ability are mixed, their synergistic effect can be doubled.

The inorganic particles having the lithium ion transferring ability refer to inorganic particles that contain a lithium element but do not store lithium but have a function of transferring lithium ions. The inorganic particles having lithium ion transferring ability exist in the particle structure Since lithium ions can be transferred and transferred due to a kind of defect, the lithium ion conductivity in the battery can be improved and the battery performance can be improved. Examples of the inorganic particles having lithium ion transferring ability include lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li _x Ti _y (PO ₄ ) ₃ , 0 <x <2, 0 <y < (Li _x Al _y Ti _z (PO ₄ ) ₃ , 0 <x <2, 0 <y <1, 0 <z <3), 14Li ₂ O-9Al ₂ O ₃ -38TiO ₂ -39P ₂ O ₅ as such (LiAlTiP) _x O _y series glass (0 <x <4, 0 <y <13), lithium lanthanum titanate _{(Li x La y TiO 3,} 0 <x <2, 0 <y <3 ), Li _{3 .25} Ge _{0 .25} P _{0 .75} S ₄ Lithium, such as germanium Mani help thiophosphate lithium nitro, such as _{(Li x Ge y P z S} w, 0 <x <4, 0 <y <1, 0 <z <1, 0 <w <5), Li 3 N fluoride _{(Li x N y, 0 <} x <4, 0 <y <2), Li 3 PO 4 -Li 2 S-SiS 2 SiS 2 based glass, such as _{(Li x Si y S z,} 0 <x <3 , 0 <y <2, 0 <z <4), LiI-Li ₂ SP ₂ S ₅ There is P ₂ S ₅ based glass _{(Li x P y S z,} 0 <x <3, 0 <y <3, 0 <z <7) or a mixture thereof as such.

As the polymer binder used for forming the porous coating layer, a polymer commonly used in the formation of the porous coating layer in the art can be used. In particular, a polymer having a glass transition temperature (T _g ) of -200 to 200 ° C can be used because it can improve mechanical properties such as flexibility and elasticity of a finally formed porous coating layer. Such a polymer binder faithfully performs a binder function to connect and stably fix inorganic particles, thereby contributing to prevention of degradation of mechanical properties of the separator into which the porous coating layer is introduced.

Further, the polymer binder does not necessarily have ion conductivity, but when the polymer having ion conductivity is used, the performance of the electrochemical device can be further improved. Therefore, a polymer binder having a high permittivity constant can be used. Actually, the dissociation degree of the salt in the electrolytic solution depends on the permittivity constant of the solvent of the electrolyte. Therefore, the higher the permittivity constant of the polymer, the better the salt dissociation degree in the electrolyte. The permittivity constant of such a polymeric binder may be in the range of 1.0 to 100 (measurement frequency = 1 kHz), in particular, 10 or more.

In addition to the functions described above, the polymeric binder may be characterized by being capable of exhibiting a high degree of swelling of the electrolyte due to gelation upon impregnation with a liquid electrolyte. Accordingly, the solubility parameter of the polymeric binder is from 15 to 45 MPa ^1/2 or 15 to 25 MPa ^1/2, and 30 to 45 MPa ^1/2 range. Therefore, hydrophilic polymers having many polar groups can be used more than hydrophobic polymers such as polyolefins. If the solubility is more than ^1/2 and less than 15 MPa 45 MPa ^1/2, because it can be difficult to swell (swelling) by conventional liquid electrolyte batteries.

Non-limiting examples of such polymeric binders include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichlorethylene, poly But are not limited to, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co- polyvinyl acetate, vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, Cyanoethylpullulan, cyanoethylpolybi Cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose can be given.

The weight ratio of the inorganic particles to the polymeric binder may be 50:50 to 99: 1, or 60:40 to 90:10, or 70:30 to 80:20.

The thickness of the porous coating layer composed of the inorganic particles and the polymer binder is not particularly limited, but may be in the range of 0.01 to 20 占 퐉. The pore size and porosity are also not particularly limited, but the pore size may be in the range of 0.01 to 10 mu m, and the porosity may be in the range of 5 to 90%.

Meanwhile, the non-aqueous electrolyte may include an organic solvent and an electrolyte salt, and the electrolyte salt is a lithium salt. The lithium salt may be any of those conventionally used for non-aqueous electrolytes for lithium secondary batteries. For example is the above lithium salt anion ^{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 ^- , or two or more of them.

Examples of the organic solvent included in the non-aqueous electrolyte include those commonly used in non-aqueous electrolytes for lithium secondary batteries, such as ether, ester, amide, linear carbonate, cyclic carbonate, etc., Two or more of them may be used in combination.

Among them, a carbonate compound which is typically a cyclic carbonate, a linear carbonate, or a mixture thereof may be included.

Specific examples of the cyclic carbonate compound include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, Propylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, vinylethylene carbonate, and halides thereof, or a mixture of two or more thereof. Examples of such halides include, but are not limited to, fluoroethylene carbonate (FEC) and the like.

Specific examples of the linear carbonate compound include any one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate and ethyl propyl carbonate And mixtures of two or more of them may be used as typical examples, but the present invention is not limited thereto.

In particular, ethylene carbonate and propylene carbonate, which are cyclic carbonates in the carbonate-based organic solvent, are high-viscosity organic solvents having a high dielectric constant and can dissociate the lithium salt in the electrolyte more easily. In addition, such cyclic carbonates can be used as dimethyl carbonate and diethyl carbonate When a low viscosity, low dielectric constant linear carbonate is mixed in an appropriate ratio, an electrolyte having a higher electric conductivity can be produced.

As the ether in the organic solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether and ethyl propyl ether or a mixture of two or more thereof may be used , But is not limited thereto.

Examples of the ester in the organic solvent include methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate,? -Butyrolactone,? -Valerolactone,? -Caprolactone,? -Valerolactone and? -Caprolactone, or a mixture of two or more thereof, but the present invention is not limited thereto.

The injection of the nonaqueous electrolyte solution can be performed at an appropriate stage of the manufacturing process of the electrochemical device according to the manufacturing process and required properties of the final product. That is, it can be applied before assembling the electrochemical device or in the final stage of assembling the electrochemical device.

Here, the electrochemical device includes all devices that perform an electrochemical reaction, and specific examples thereof include capacitors such as all kinds of secondary cells, fuel cells, solar cells, or super-capacitor devices. Particularly, a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery among the above secondary batteries is preferable.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

10: electrode current collector 20: first electrode active material layer
21: First electrode active material 30: Second electrode active material layer
31: second electrode active material 100, 200: electrode

Claims (14)

Electrode collector;
A first electrode active material layer formed on at least one surface of the electrode current collector and including a first electrode active material having a particle size of 1 to 20 m; And
And a second electrode active material layer formed on the first electrode active material layer and including a second electrode active material having a particle size of 10 to 100 占 퐉. The method according to claim 1,
Wherein the first electrode active material layer has a specific surface area of 0.1 to 20 m ² / g. The method according to claim 1,
And the specific surface area of the second electrode active material layer is 0.01 to 5 m ² / g. The method according to claim 1,
Wherein the ratio of the thickness of the first electrode active material layer to the thickness of the second electrode active material layer is 20:80 to 80:20. The method according to claim 1,
Wherein the electrode is an anode, and the first electrode active material and the second electrode active material are lithium-containing oxides, respectively. 6. The method of claim 5,
Wherein the lithium-containing oxide is a lithium-containing transition metal oxide. The method according to claim 6,
The lithium-containing transition metal _{oxides, Li x CoO 2 (0.5 <} x <1.3), Li x NiO 2 (0.5 <x <1.3), Li x MnO 2 (0.5 <x <1.3), Li x Mn 2 O 4 (0.5 <x <1.3), Li x (Ni a Co b Mn c) O 2 (0.5 <x <1.3, 0 <a <1, 0 <b <1, 0 <c <1, a + b + c 1), Li _x Ni _{1- y} Co _y O ₂ (0.5 <x <1.3, 0 <y <1), Li _x Co _{1 -y} Mn _y O _{2 ), Li x Ni 1 -y Mn} y O 2 (0.5 <x <1.3, O≤y <1), Li x (Ni a Co b Mn c) O 4 (0.5 <x <1.3, 0 <a <2 , 0 <b <2, 0 <c <2, a + b + c = 2), Li x Mn 2 -z Ni z O 4 (0.5 <x <1.3, 0 <z <2), Li x Mn 2 in _{-z Co z O 4 (0.5 <} x <1.3, 0 <z <2), Li x CoPO 4 (0.5 <x <1.3) and _{Li x FePO 4 (0.5 <x} <1.3) which is selected from the group consisting of One or a mixture of two or more thereof. The method according to claim 1,
Wherein the electrode is a cathode, and the first electrode active material and the second electrode active material are each selected from the group consisting of lithium metal, carbonaceous material, and metal compound, or a mixture of two or more thereof. 9. The method of claim 8,
The metal compound is selected from the group consisting of Si, Ge, Sn, Pb, P, Sb, Bi, Al, Ga, In, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ag, Or a mixture of two or more thereof. An electrode assembly including an anode, a cathode, and a separator interposed between the anode and the cathode;
A nonaqueous electrolytic solution for impregnating the electrode assembly; And
And a battery case housing the electrode assembly and the non-aqueous electrolyte,
Wherein at least one of the positive electrode and the negative electrode is the electrode of claim 1. 11. The method of claim 10,
Wherein the non-aqueous electrolyte comprises an organic solvent and an electrolyte salt. 12. The method of claim 11,
Examples of the organic solvent include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, (DEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate A solvent such as methanol, ethanol, propanol, isopropanol, isopropanol, butanol, isopropanol, butanol, isopropanol, Pyronate,? -Butyrolactone,? -Valerolactone,? -Caprolactone,? -Valerolactone and? -Caprolactone The electrochemical device according to claim any one or a mixture of two or more of those selected from the group true luer. 12. The method of claim 11,
The electrolyte salt includes, as ^{anions, 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 ^- , or two or more of them. 11. The method of claim 10,
Wherein the electrochemical device is a lithium secondary battery.

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