KR20180113404A - Electrode with pattern and secondary battery comprising the same - Google Patents

Abstract

The present invention relates to an electrode assembly for a secondary battery including an electrode and a separator. The electrode includes a current collector and an active material layer formed on at least one surface of the current collector, wherein a macro pattern and a micro pattern are formed on the active material layer. The macro pattern includes voids having a width in a range of 10-1000 μm, and the micro pattern is formed as a groove having a width in a range of 1-100 μm. The secondary battery including the electrode assembly not only enhances the electrolyte impregnability but also has an effect of preventing cathode dendrite formation and enhancing the anode output characteristics.

Description

[0001] The present invention relates to a patterned electrode and a secondary battery including the same,

The present invention relates to a patterned electrode and a secondary battery comprising the same.

2. Description of the Related Art Recently, compact and lightweight electric / electronic devices such as mobile phones, notebook computers, camcorders, and the like have been actively developed and produced. Such electric / storage devices can be operated in a place where no separate power source is provided It has a built-in battery pack.

In addition, automobiles using motors such as hybrid vehicles (HV), electric vehicles (EV), and electric vehicles are being developed and produced, and battery packs capable of driving motors are also incorporated in such vehicles. The battery pack is provided with at least one battery for outputting a predetermined level of voltage for driving the electric / storage device or the automobile for a predetermined time.

Considering the economical aspect, recently, the battery pack employs a rechargeable / rechargeable secondary battery. The secondary battery is typically a nickel-cadmium (Ni-Cd) battery, a nickel-hydrogen (Ni-MH) battery, a lithium battery, or a lithium secondary battery such as a lithium ion battery.

Among them, the lithium secondary battery is generally classified into a liquid electrolyte cell and a polymer electrolyte cell depending on the kind of electrolyte, a battery using a liquid electrolyte is called a lithium ion battery, and a battery using a polymer electrolyte is called a lithium polymer battery .

In the case of a lithium secondary battery using a nonaqueous electrolyte, the electrode has an electrode active material layer formed on at least one surface of the current collector, and the active material layer is coated on the current collector without a specific pattern as shown in FIGS. Or formed on the current collector with grooves on the surface in contact with the separator as shown in Figs. 2A and 2B.

In such an electrode, the ion mobility in the electrolyte is not sufficiently secured, so that the impregnation of the electrolyte into the electrolyte may not be accomplished in a short period of time. If the electrolytic solution impregnation is not carried out quickly, problems occur in the battery manufacturing process and the life characteristics of the battery are deteriorated. Therefore, it is necessary to shorten the electrolytic solution impregnating process time.

In addition, as described above, since the lithium secondary battery is expanded to automobiles and the like, rapid charging must be performed to shorten the charging time. At the same time, there is a problem that the battery, which is caused by exposure to high temperature, Safety is ensured in the event of a failure, which is a phenomenon in which the battery reaches an abuse situation due to internal, external short, overcharge, over discharge, abnormal reaction occurs and thermal burst occurs due to the chain reaction There is a technical problem in the art. In addition, as the charging and discharging of the lithium secondary battery progresses, there is known a problem that the electrolyte is depleted and gas is generated. Also, it is known that the volume expansion of the Si-based negative electrode active material for increasing the capacity is also a technical problem to be solved in the art.

The present invention provides an electrode having improved electrolyte impregnation characteristics.

It is also intended to provide an electrode that prevents the formation of dendrites at the cathode even at rapid charging and has an output improving effect at the anode.

Also, it is an object of the present invention to provide an electrode that can prevent or minimize thermal propagation even if a failure occurs at a specific position in a cell.

Also, it is an object of the present invention to provide an electrode capable of minimizing expansion in the thickness direction even when an electrode active material having a large volume change such as silicon is used.

Also, it is an object of the present invention to provide an electrode which is advantageous in terms of gas generation and depletion of electrolyte, thereby securing a service life.

According to an aspect of the present invention, there is provided an electrode assembly for a secondary battery comprising an electrode and a separator, wherein the electrode includes a current collector and an active material layer formed on at least one surface of the current collector, wherein the macro pattern comprises voids having a width in the range of 10 탆 to 1000 탆 and the micropattern has a width in the range of 1 탆 to 100 탆 The electrode assembly comprising: an electrode assembly for a secondary battery;

The voids may be formed in the electrode active material layer at intervals of 0.1 mm to 10 cm.

The gap may be formed to a depth of the thickness of the electrode active material layer.

And a polymer material may be inserted into the gap.

The grooves may be formed in the electrode active material layer at intervals of 10 탆 to 10 mm.

The grooves may have a depth of 5 占 퐉 to the thickness of the electrode active material layer.

And a polymer material may be inserted into the groove.

According to another aspect of the present invention, there is provided a method of manufacturing the aforementioned electrode assembly for a secondary battery, comprising the steps of:

(S1) preparing an electrode current collector having a macromolecular pattern material attached thereto;

(S2) forming an electrode active material layer so as to form a gap around the polymer material;

(S3) forming a micropattern groove in the electrode active material layer;

(S4) preparing a separation membrane to which a polymer material for a micropattern is attached; And

(S5) assembling the separation membrane and the electrode to insert the polymer material for micropattern into the micropattern groove.

In the active material layer according to an embodiment of the present invention, a macro pattern and a micro pattern are formed, and the following effects are obtained.

When a thermal shock occurs due to a failure occurring at a specific position within a cell due to a macro pattern according to an embodiment of the present invention, the polymer compound contained in the pattern may cause diffusion of a short- And can be prevented by detouring. In the case where the polymer material is contained in the pores of the macro pattern, the polymer compound is melted to absorb heat, and the molten polymer blocks the reaction site to prevent additional abuse reaction, it is possible to minimize the effect of failure propagation.

In addition, due to the macro pattern, the electrolytic solution is moved in the north-south direction and the east-west direction along the pattern during the electrolytic solution impregnation step, so that the electrolytic solution impregnation can be completed faster than in the past. This electrolyte impregnation effect is partially generated in the micropattern, but occurs mainly in the macropattern since the macropattern has a larger cross-sectional area than the micropattern.

On the other hand, due to the large number of micropatterns formed on the electrode, a bulk electrolyte penetrates deeply into the electrode, so that in the case of the negative electrode, it is advantageous to avoid formation of lithium dendrite under rapid charging conditions, In the case of the anode, the output can be improved. In addition, the magnitude of overpotential appearing on both sides of the separator is reduced. Therefore, the side reaction is reduced, and gas generation and electrolyte depletion are reduced, which is advantageous in securing a service life. This effect is remarkable in a micropattern having a larger number than the macro pattern.

In addition, since voids are present in repeated patterns in the electrode, the stress generated upon expansion of the cell electrode is eliminated as planar displacement, thereby minimizing the expansion in the thickness direction. Particularly, It is advantageous when used as an active material.

In addition, the macro pattern and the micro pattern according to one embodiment of the present invention can serve as a passage for allowing the gases generated during the degeneration process to escape from the reaction site to a place where the reaction does not occur. The provision of the gas discharge passages reduces cell swelling and also alleviates or eliminates delamination problems.

FIGS. 1A and 1B are schematic side and front views of a conventional electrode in which no pattern is formed.
2A and 2B are schematic side and front views of a conventional electrode having a linear pattern.
3 is a side cross-sectional view of an electrode according to one embodiment of the present invention.
FIG. 4A is a schematic top view of an electrode with reference to line 'A' in FIG.
And FIG. 4B is a schematic top view of the electrode with reference to line B 'in FIG.
FIG. 5 shows the charging and discharging curves of the batteries manufactured in the examples and the comparative examples, respectively.
FIG. 6A shows the electrolyte salt concentration (mol / m 3) of the electrode after discharge of the embodiment cell, and FIG. 6B shows the electrolyte salt concentration (mol / m 3) of the electrode after discharging the discharge cell of the comparative cell.
FIG. 7A shows the electrolyte salt concentration (mol / m 3) of the electrode after charging the battery of the embodiment, and FIG. 7B shows the electrolyte salt concentration (mol / m 3) of the electrode after charging the battery of the comparative example.
FIG. 8A shows the SOC (state of charge) of the electrode after discharge of the embodiment cell, and FIG. 8B shows the SOC of the discharge electrode of the discharge cell of the comparative battery.
FIG. 9A shows the SOC (state of charge) of the electrode after discharge of the battery of the embodiment, and FIG. 9B shows the SOC of the electrode after discharge of the battery of the comparative battery.
Fig. 10A shows the reaction current (A / m < 3 >) of the electrode after discharge in the embodiment cell, and Fig. 10B shows the reaction current (A / m < 3 >
Fig. 11A shows the reaction current (A / m < 3 >) of the electrode after charging the battery of the embodiment, and Fig. 11B shows the reaction current (A / m < 3 >

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. It should be understood, however, that the following description of the preferred embodiments of the present invention is provided for the purpose of describing the present invention and for the understanding of the technical idea of the present invention. But is not limited thereto.

The present invention provides a secondary battery, an electrode assembly comprising an electrode and a separator, wherein the electrode comprises a current collector, and the active material layer formed on at least one surface of the current collector, and macro pattern on the active material layer (macro pattern) And a micro pattern are formed on the surface of the electrode assembly.

In the present specification, the term 'macro pattern' refers to a concept distinguished from 'micro pattern', and both 'macro pattern' and 'micro pattern' refer to a pattern generated by the absence of an active material layer on the electrode current collector , Macro patterns are formed in a wider width than the micro patterns, and are formed in a smaller number than the micro patterns. However, the depth of the macro pattern is always the same as the thickness of the electrode active material layer, that is, the porous electrode active material layer is discontinuous with respect to the macro pattern, while the depth of the micropattern may be smaller than the thickness of the porous electrode active material layer. The active material layer can form a continuum independently of the micropattern.

Since the lithium ion concentration of the electrolyte is an important factor affecting battery performance when the lithium ion battery is charged and discharged, if the pattern is formed on the electrode, the effect of improving the charge / discharge performance by increasing the effective lithium diffusion coefficient ≪ / RTI >

That is, when the porous electrode active material layer is considered as a macro-homogeneous porous medium, the lithium ion diffusion of the electrolyte in the porous electrode active material layer will use the concept of effective diffusion coefficient expressed by the following formula:

[Equation 1]

D ^effective = D ^intrinsic x (effectiveness factor)

In this formula,

D ^intrinsic is the lithium ion diffusion coefficient measured in the electrolyte and the effectiveness factor indicates the effective factor due to the porous structure.

A typical expression of the effectiveness factor is the Bruggeman correlation, which is porosity ^ 1.5. In lithium-ion batteries, it is also expressed as porosity ^ tortuosity or porosity / tortuosity. According to the definition of each term, since the porosity can not be greater than 1 and the tortuosity can not be less than 1, the effectiveness factor is always less than 1. Therefore, the effective diffusion coefficient in the porous electrode active material layer is always smaller than the diffusion coefficient measured in the electrolytic solution. Accordingly, in the present invention, by applying a specific pattern to the electrode, the effective factor is increased to increase the effective lithium diffusion coefficient.

3 schematically illustrates a cross-sectional view of an electrode according to one embodiment of the present invention.

3, the voids constituting the macro pattern are represented by '100', the macromolecular materials embedded in the macro pattern are represented by '110' and '120' Quot; 200 ", and the polymeric substance contained in the micro pattern is represented by " 210 ".

In the present specification, 'voids' can be formed in a vertical direction over the entire thickness of the electrode active material layer, and form a macro pattern on the electrode active material layer. For example, a lattice pattern can be formed. Further, in one embodiment, the polymer material may be contained or inserted into the void. Such a macro pattern may have a width in the range of 10 탆 to 1000 탆, and may be formed in an interval of 0.1 mm to 10 cm. The macro pattern has a higher permeability than that of the porous electrode, so that the micropattern can be easily impregnated into the electrolyte according to the multi-phase flow theory and contribute to minimizing heat propagation.

The macromolecular material (macromolecular polymer material) included in or inserted into the macro pattern may be spaced from the sidewall of the cavity and may occupy 10 to 90% of the pore volume. Since a certain space is formed between the electrode active material and the polymer material in the pores, cell swelling can be prevented by acting as a space in which gas generated due to the electrolyte side reaction acts as a trapping space. The polymer material may be a film-like material formed from an insulating polymer resin commonly used in the art, but is not limited thereto. Non-limiting examples of the insulating polymer resin include high density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, high crystalline polypropylene, A polyethylene-propylene copolymer, a polyethylene-butylene copolymer, a polyethylene-hexene copolymer, a polyethylene-octene copolymer, Polystyrene-butylene-styrene copolymers, polystyrene-ethylene-butylene-styrene copolymers, polystyrene, polyphenylene oxides, oxide, polysulfone, polycarbonate, polyester, poly Polyamide, polyurethane, polyacrylate, polyvinylidene chloride, polyvinylidene fluoride, polysiloxane, polyolefin, ionomer, and the like. ), Polymethyl pentene, hydrogenated oligocyclopentadiene (HOCP), polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, poly Ether ether ketone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene, and derivatives thereof, or a mixture of two or more thereof. The polymeric material may be formed of one kind of compound, but as shown in FIG. 3, two or more polymeric materials, that is, a predetermined polymeric material 120 constitute a core, (110) may be included or inserted into the cavity in a surrounding manner.

The shape of the voids and the types of the polymer material included therein may be the same throughout the voids, but may be configured to be two or more types and types.

In the present specification, 'groove' means a recess formed over all or a part of the thickness of the electrode active material layer, and the groove may form a micro pattern. For example, a lattice pattern can be formed, wherein the lattice formed by the micro pattern has a smaller size than the lattice formed by the macro pattern. Also, in one embodiment, the grooves may include or include a polymeric material. The grooves may have a width in the range of 1 탆 to 100 탆 and may have a depth of 5 탆 to the entire thickness of the active material layer, depending on the electrode design. The grooves may be non-restrictively V-shaped, or a blunt-ended V-shape. The shape of the groove and the type of the polymer material included therein may be the same throughout the cavity, but may be configured to be two or more types and types. In addition, the micropattern may be formed at intervals of several tens of micrometers (mu m) to several millimeters (mm) in the electrode active material layer, for example, at intervals of 10 mu m to 10 mm. The micropattern has an effect of providing a large reaction area capable of coping with a large reaction and also has an effect of alleviating concentration unevenness by increasing the effective diffusion coefficient of the salt in the electrolytic solution, so that rapid charging and output improvement effect can be obtained.

The polymer material ('polymer material for micropattern') included in or inserted into the micropattern may be spaced from the groove side wall and may occupy 10 to 90% of the groove volume. Since a certain space is formed between the electrode active material and the polymeric material in the groove, the contact area between the porous electrode and the bulk electrolyte is wide and it is advantageous for the movement of the salt in the electrolyte. The polymer material may be the same as or different from the macromolecular polymer material, and may be a film-like material formed from an insulating polymer resin commonly used in the art, but is not limited thereto. Non-limiting examples of the insulating polymer resin include high density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, high crystalline polypropylene, A polyethylene-propylene copolymer, a polyethylene-butylene copolymer, a polyethylene-hexene copolymer, a polyethylene-octene copolymer, Polystyrene-butylene-styrene copolymers, polystyrene-ethylene-butylene-styrene copolymers, polystyrene, polyphenylene oxides, oxide, polysulfone, polycarbonate, polyester, poly Polyamide, polyurethane, polyacrylate, polyvinylidene chloride, polyvinylidene fluoride, polysiloxane, polyolefin ionomer, and the like. but are not limited to, ionomers, polymethylpentene, hydrogenated oligocyclopentadiene (HOCP), polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide , Polyether ether ketone, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalene, and derivatives thereof, or a mixture of two or more thereof.

FIGS. 4A and 4B schematically show the electrode according to one embodiment of the present invention viewed from above according to the height of the electrode active material layer. More specifically, FIG. 4A is a top view of the active material layer at a height ('A') where both voids and grooves are present, FIG. 4B is a top view of the active material layer at a height ('B' Fig.

Referring to FIG. 4A, the electrode according to an embodiment of the present invention includes microelectrode patterns and macro patterns with an electrode active material layer spaced apart from a polygonal shape at a height of 'A' Each of the pattern voids contains or inserts a polymer material as described above. The polygon may be, for example, a triangle, a rectangle, a hexagon, an octagon, a cross, etc. The rectangle may include a rectangle, a rhombus, and the like. It is preferable that the lattice type is used in view of improving the impregnation improvement effect at the center of the electrode while minimizing the reduction in the capacity of the battery.

In addition, referring to FIG. 4B, the electrode according to an embodiment of the present invention may be formed as a macro pattern by separating the electrode active material layer in a polygonal shape having a larger area than the polygon shown in FIG. 4A at a height of 'B' The macropattern polymer material as described above is contained or inserted into the pattern pores. The polygon may be, for example, a triangle, a quadrangle, a hexagon, an octagon, a cross, or the like similar to that in the micropattern, and the rectangle may include a rectangle, a rhombus and the like. It is preferable that the lattice type is used in view of improving the impregnation improvement effect at the center of the electrode while minimizing the reduction in the capacity of the battery.

According to another aspect of the present invention, pattern shapes and materials of the anode and the anode can be designed differently so that dendrite formation of the cathode is prevented and the output of the anode is improved.

In the present invention, the electrode slurry used for forming the active material application region of the electrode active material layer is not particularly limited and a conventionally used electrode slurry may be used. For example, an electrode slurry can be prepared by mixing and stirring a solvent, a binder, a conductive material, a dispersing material, etc., with each of the cathode active material and the anode active material.

The cathode active material is not particularly limited, and a material conventionally used as a cathode active material may be used. Non-limiting _{example, 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 < 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 (0.5 <x <1.3) , And the lithium-containing transition metal oxide may be coated with a metal such as aluminum (Al) or a metal oxide. As a non-limiting example, the three-component cathode active material is a lithium oxide having a nickel: manganese and cobalt composition of 1: 1: 1, a lithium oxide having a nickel: manganese and cobalt composition of 5: 3: 2, nickel, Lithium oxide with a 6: 2: 2 lithium oxide, nickel, manganese, and cobalt composition of 8: 1: 1 may be used. In addition to the lithium-containing transition metal oxide, sulfide, selenide and halide may be used, but the present invention is not limited thereto.

The negative electrode active material is not particularly limited and those conventionally used as negative electrode active materials may be used. For example, carbon materials such as crystalline carbon, amorphous carbon, carbon composites and carbon fibers, lithium metal, alloys of lithium and other elements, silicon or tin, and the like. Examples of the amorphous carbon include hard carbon, coke, mesocarbon microbead (MCMB) calcined at 1500 ° C or less, and mesophase pitch-based carbon fiber (MPCF). The crystalline carbon is a graphite-based material, specifically natural graphite, graphitized coke, graphitized MCMB, and graphitized MPCF. Other elements constituting the alloy with lithium include, but are not limited to, aluminum, zinc, bismuth, cadmium, antimony, silicon, lead, tin, gallium or indium.

As the solvent, usually a non-aqueous solvent or water may be used. Examples of the non-aqueous solvent include N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, N, N-dimethylaminopropylamine, ethylene oxide and tetrahydrofuran , But is not limited thereto.

As the binder, those used in the art can be used without any particular limitation, and examples thereof include vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF) An organic binder such as polyacrylonitrile or polymethylmethacrylate or an aqueous binder such as styrene-butadiene rubber (SBR) may be used together with a thickener such as carboxymethylcellulose (CMC).

The conductive material may be at least one material selected from the group consisting of a graphite conductive material, a carbon black conductive material, and a metal or metal compound conductive material, which improves the electronic conductivity. Examples of the black electroconductive material include artificial graphite and natural graphite. Examples of the carbon black conductive material include acetylene black, ketjen black, denka black, thermal black, channel black ( channel black). Examples of metal or metal compound conductive materials include perovskite materials such as tin, tin oxide, tin phosphate (SnPO ₄ ), titanium oxide, potassium titanate, LaSrCoO ₃ , and LaSrMnO ₃ have. However, the present invention is not limited to the above-mentioned conductive materials.

The thickening agent is not particularly limited as long as it can control the viscosity of the active material slurry. For example, carboxymethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose and the like can be used.

The current collector according to the present invention may be an anode current collector or a cathode current collector.

The current collector of the metal material is a metal having high conductivity and easily adhered to the slurry of the positive electrode or the negative electrode active material, and any of them may be used as long as it is not reactive in the voltage range of the battery.

The negative electrode current collector may be made of copper or a copper alloy, but the present invention is not limited thereto. The surface of the stainless steel, nickel, copper, titanium or alloys thereof, copper or stainless steel may be subjected to surface treatment with carbon, nickel, Or the like may be used.

The anode current collector may be made of aluminum or an aluminum alloy, but the present invention is not limited thereto. The surface of the stainless steel, nickel, aluminum, titanium or an alloy thereof, aluminum or stainless steel may be subjected to surface treatment with carbon, nickel, Or the like may be used.

The form of the current collector is not particularly limited, and a commonly used form can be used. For example, a planar current collector, a hollow current collector, a wire-like current collector, a wound wire-like current collector, a wound sheet-like current collector, a mesh-like current collector, or the like can be used.

One embodiment of the method of making an electrode assembly of the present invention may include, but is not limited to, the following steps:

(S1) preparing an electrode current collector having a macromolecular pattern material attached thereto;

(S2) forming an electrode active material layer on the current collector of the electrode, and forming an electrode active material layer so as to form a gap around the macromolecular polymer material;

(S3) forming a micropattern groove in the electrode active material layer;

(S4) preparing a separation membrane to which a polymer material for a micropattern is attached; And

(S5) assembling the separation membrane and the electrode to insert the polymer material for micropattern into the micropattern groove.

More specifically, in one embodiment, the polymeric material used in the macro pattern is attached to the electrode current collector foil, and then the electrode active material slurry is applied and dried ('electrode active material layer') so that macro patterned voids are formed. Is transferred and coated on the current collector foil, and then micro patterned grooves are formed in the electrode active material layer by laser irradiation. On the other hand, a polymer material included in or inserted into the micropattern groove is attached to one surface of the separation membrane to be used together with the electrode. Subsequently, an electrode in which the micropattern groove is formed in the electrode active material layer and a separation membrane to which the polymer material for micropattern is attached are assembled.

Alternatively, in another embodiment, the polymeric material used in the macro pattern is attached to the electrode current collector foil, and then the electrode active material slurry is applied and dried so as to form macro pattern voids, and then the electrode active material layer Thereby forming micro pattern grooves. On the other hand, a polymer material included in or inserted into the micropattern groove is attached to one surface of the separation membrane to be used together with the electrode. Subsequently, an electrode in which the micropattern groove is formed in the electrode active material layer and a separation membrane to which the polymer material for micropattern is attached are assembled.

Alternatively, in another embodiment, the active material slurry is discontinuously coated on the electrode current collector by adjusting the nozzle spacing in a manner different from the above-mentioned (S1) to (S5), and the non- The polymer material can be inserted. In this case, the macromolecular polymer material may be inserted separately from the separation membrane, or the macromolecular polymer material may be inserted into the pores by assembling the separation membrane with the electrode with the macromolecular polymer material attached to the separation membrane. When the macromolecular polymer material is attached to the separation membrane, the macromolecular polymer material and the micro pattern polymer material attached to the separation membrane may have different heights.

The method of coating (coating) the electrode slurry on the current collector of the electrode may be selected from known methods in consideration of the characteristics of the material, or may be carried out by a new suitable method. For example, the electrode slurry may be uniformly dispersed on a current collector by a method of uniformly applying the electrode slurry on the electrode current collector, and then dispersed using a doctor blade or the like. In some cases, a method of performing the distribution and dispersion processes in a single process may be used. Other methods such as die casting, comma coating, and screen printing may be used, or they may be formed on a separate partition and bonded to the current collector by a pressing or lamination method.

The drying of the electrode slurry applied over the current collector can be carried out in a vacuum oven at 50 ° C to 200 ° C for 12 to 72 hours.

The electrode for a lithium secondary battery of the present invention may be at least one of a negative electrode and a positive electrode. The present invention provides a lithium secondary battery including the positive electrode, the negative electrode, a separator interposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte.

The lithium secondary battery of the present invention is manufactured by forming an electrode structure in which a separator is interposed between a positive electrode and a negative electrode, storing the electrode structure in a battery case, and injecting an electrolyte solution thereinto.

As the separator, a conventional porous polymer film conventionally used as a separator, for example, a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer Or a nonwoven fabric made of conventional porous nonwoven fabric such as high melting point glass fiber or polyethylene terephthalate fiber can be used, but the present invention is not limited thereto . As a method of applying the separator to a battery, lamination, stacking and folding of a separator and an electrode can be performed in addition to a general method of winding.

The nonaqueous electrolytic solution may include a lithium salt as an electrolyte and an organic solvent.

The lithium salt may be any of those conventionally used in an electrolyte for a lithium secondary battery, and may be represented by Li ⁺ X ^- . In this lithium salt anion is not particularly ^{limited, F -, Cl -, Br} -, I -, NO 3 -, N (CN) 2 -, BF 4 -, ClO 4 -, PF 6 -, (CF 3) _{^{2PF 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 ^- can do.

Examples of the organic solvent include, but are not limited to, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, dipropyl carbonate, dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, vinylene carbonate, sulfolane, gamma-butyrolactone , Propylene sulfite, and tetrahydrofuran, or a mixture of two or more thereof.

The aforementioned non-aqueous electrolyte solution is injected into an electrode structure composed of a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode to manufacture a lithium secondary battery.

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.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Examples and Comparative Examples

Example  One

 <Anode>

The cathode active material is a three-component lithium oxide (trade name: MX7h, manufactured by UM: manufactured by Nikki Chemical Co., Ltd.) and lithium manganese oxide (trade name: E06Z manufactured by Nikki Chemical Co., Ltd.) and nickel, manganese and cobalt in a 1: ) Were used in combination at a composition ratio of 3: 7. A slurry was prepared using carbon black (trade name: Denka black, trade name: Denka) as a conductive material and PVDF (trade name: KF-series, manufactured by Kureha) as a binder at a mixing ratio of 91.5: 4.4: 4.1 , And this slurry was coated on an aluminum foil collector of 12 mu m thickness to a thickness of about 60 mu m.

<Cathode>

(Trade name: Denka black, manufactured by Denka) and PVDF (trade name: KF-series, manufactured by Kureha) as a binder, using a graphite-based material (trade name: AGM01, manufactured by Mitsubishi Company) To prepare an anode slurry. The composition ratio of the negative electrode active material, the conductive material, and the binder was 95.8: 2: 2.2. The negative electrode slurry was coated on a copper foil current collector having a thickness of 8 mu m to a thickness of about 65 mu m.

<Patterning>

The patterns of the positive electrode and the negative electrode were applied in the same manner, and the pattern was as follows. For the macro pattern, pores having a width of 30 μm were formed at intervals of 0.6 mm, and grooves having a width of 10 μm were formed at intervals of 200 μm for a micropattern. The voids of the macro pattern and the grooves of the micro pattern are formed to have the same depth as the thickness of the active material layer, and polypropylene is inserted into the voids and grooves.

<Secondary Battery>

A battery was constructed by laminating a positive electrode plate and a negative electrode plate and inserting a three-layer separator (total thickness 16.4 μm) between the positive electrode plate and the negative electrode plate. As the electrolyte, 1M LiPF ₆ solution Were selected.

Comparative Example  One

A secondary battery was fabricated in the same manner as in Example 1, except that the electrode slurry was continuously coated on the current collector foil in a pattern free of electrodes.

Experimental Example

Evaluation of the lithium secondary batteries of Examples and Comparative Examples was carried out as follows.

For the rapid charge test, the battery was charged at a room temperature of 25 ° C and a SOC (state of charge) = 10% for 300 seconds at 5 C rate current.

For the high-power test, the battery was discharged at a room temperature of 25 ° C and SOC = 90% at a current of 5 C for 300 seconds.

(1) Charge / discharge evaluation

The electron potential difference between the positive electrode and the negative electrode was measured as the cell voltage with respect to the above evaluation conditions. The results are shown in FIG. 5, and as can be seen from FIG. 5, the battery according to the present embodiment showed a favorable charging / discharging curve compared with the battery of the comparative example.

(2) Analysis of distribution of electrolyte salt (the left side of the drawing is the cathode, and the right side is the anode)

The distribution of the charge / discharge test time 300 seconds is discharged (FIGS. 6A and 6B) and the charge (degree of charge (discharge)) is assumed as the design condition of the electrolyte salt concentration 1 M (= 1000 mol / 7a and 7b).

In each drawing, there is shown a cross section of a cathode, a separator, and a positive electrode formed by coating a cathode active material layer on a cathode current collector coated with a negative electrode active material layer. The left side of the figure shows the cathode, the right side shows the anode, and the middle shows the separator. From the comparison of the numerical range of the electrolyte salt concentration of FIG. 6A, that is, the numerical range of 453.966 to 1729.36 mol / m 3 and the electrolyte salt concentration of FIG. 6b, that is, 379.729 to 1835.54 mol / m 3, It can be confirmed that the concentration distribution is more uniform. Similarly, from the comparison between Figs. 7A and 7B, it can be confirmed that the cell of the embodiment has more uniform electrolyte salt concentration distribution in the electrode than the battery of the comparative example.

(3) SOC analysis (the left side of the drawing is the cathode, and the right side is the anode)

Charge / Discharge Test The SOC distribution of the active material surface at the time of 300 seconds was shown for discharge (FIGS. 8A and 8B) and charge (FIGS. 9A and 9B). At this time, the SOC definition of the surface of the active material is as follows.

SOC, particle surface = particle surface Li concentration / theoretical maximum available Li concentration

8A and 8B and a comparison between FIGS. 9A and 9B, it can be seen that the SOC distribution in the electrode of the embodiment battery is more uniform than that of the comparative battery. Particularly, in the charging condition, the maximum SOC of FIG. 9A is smaller than the maximum SOC of FIG. 9B, which clearly shows that it is advantageous for rapid charging.

(4) Reaction current analysis (the left side of the drawing is the cathode and the right side is the anode)

The reaction current is obtained from the Butler-Volmer equation or Li-ion insertion / desertion kinetic expression and corresponds to "[A / ㎡]" in the following equation.

[Equation 1]

In the figure below, '' is multiplied by the specific surface area [m 2 / m 3] per unit volume, and is expressed as a unit of current per unit volume [A / m 3].

Comparison of FIGS. 10A and 10B and comparison of FIGS. 11A and 11B confirm that the reaction current distribution in the electrode is more uniform than that of the comparative secondary battery.

Claims (8)

An electrode assembly for a secondary battery comprising an electrode and a separator,
Wherein the electrode includes a current collector and an active material layer formed on at least one surface of the current collector, wherein a macro pattern and a micro pattern are formed on the active material layer, Wherein the micro pattern comprises grooves having a width in the range of 1 占 퐉 to 100 占 퐉, wherein the micro pattern comprises grooves having a width in the range of 占 퐉 to 1000 占 퐉.
The method according to claim 1,
Wherein the voids are formed in the electrode active material layer at intervals of 0.1 mm to 10 cm.
The method according to claim 1,
Wherein the gap is formed at a depth of the thickness of the electrode active material layer.
The method according to claim 1,
And a polymer material is inserted in the gap.
The method according to claim 1,
Wherein the grooves are formed in the electrode active material layer at intervals of 10 占 퐉 to 10 mm.
The method according to claim 1,
Wherein the groove has a depth of 5 占 퐉 to an electrode active material layer thickness.
The method according to claim 1,
And a polymer material is inserted in the groove.
A method of manufacturing an electrode assembly for a secondary battery according to claim 1, comprising the steps of:
(S1) preparing an electrode current collector having a macromolecular pattern material attached thereto;
(S2) forming an electrode active material layer so as to form a gap around the polymer material;
(S3) forming a micropattern groove in the electrode active material layer;
(S4) preparing a separation membrane to which a polymer material for a micropattern is attached; And
(S5) assembling the separation membrane and the electrode to insert the polymer material for micropattern into the micropattern groove.

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